11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 31da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 41da177e4SLinus Torvalds * interface as the means of communication with the user level. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Implementation of the Transmission Control Protocol(TCP). 71da177e4SLinus Torvalds * 802c30a84SJesper Juhl * Authors: Ross Biro 91da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 101da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 111da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 121da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 131da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 141da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 151da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 161da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 171da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 181da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 191da177e4SLinus Torvalds */ 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds /* 221da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 231da177e4SLinus Torvalds * : Fragmentation on mtu decrease 241da177e4SLinus Torvalds * : Segment collapse on retransmit 251da177e4SLinus Torvalds * : AF independence 261da177e4SLinus Torvalds * 271da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 281da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 291da177e4SLinus Torvalds * during syn/ack processing. 301da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 311da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 321da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 331da177e4SLinus Torvalds * J Hadi Salim : ECN support 341da177e4SLinus Torvalds * 351da177e4SLinus Torvalds */ 361da177e4SLinus Torvalds 371da177e4SLinus Torvalds #include <net/tcp.h> 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds #include <linux/compiler.h> 405a0e3ad6STejun Heo #include <linux/gfp.h> 411da177e4SLinus Torvalds #include <linux/module.h> 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 44ab32ea5dSBrian Haley int sysctl_tcp_retrans_collapse __read_mostly = 1; 451da177e4SLinus Torvalds 4615d99e02SRick Jones /* People can turn this on to work with those rare, broken TCPs that 4715d99e02SRick Jones * interpret the window field as a signed quantity. 4815d99e02SRick Jones */ 49ab32ea5dSBrian Haley int sysctl_tcp_workaround_signed_windows __read_mostly = 0; 5015d99e02SRick Jones 511da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 521da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 531da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 541da177e4SLinus Torvalds */ 55ab32ea5dSBrian Haley int sysctl_tcp_tso_win_divisor __read_mostly = 3; 561da177e4SLinus Torvalds 57ab32ea5dSBrian Haley int sysctl_tcp_mtu_probing __read_mostly = 0; 5897b1ce25SShan Wei int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS; 595d424d5aSJohn Heffner 6035089bb2SDavid S. Miller /* By default, RFC2861 behavior. */ 61ab32ea5dSBrian Haley int sysctl_tcp_slow_start_after_idle __read_mostly = 1; 6235089bb2SDavid S. Miller 63519855c5SWilliam Allen Simpson int sysctl_tcp_cookie_size __read_mostly = 0; /* TCP_COOKIE_MAX */ 64e6b09ccaSDavid S. Miller EXPORT_SYMBOL_GPL(sysctl_tcp_cookie_size); 65519855c5SWilliam Allen Simpson 66519855c5SWilliam Allen Simpson 6767edfef7SAndi Kleen /* Account for new data that has been sent to the network. */ 68cf533ea5SEric Dumazet static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) 696ff03ac3SIlpo Järvinen { 706ff03ac3SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 7166f5fe62SIlpo Järvinen unsigned int prior_packets = tp->packets_out; 729e412ba7SIlpo Järvinen 73fe067e8aSDavid S. Miller tcp_advance_send_head(sk, skb); 741da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 758512430eSIlpo Järvinen 7625985edcSLucas De Marchi /* Don't override Nagle indefinitely with F-RTO */ 778512430eSIlpo Järvinen if (tp->frto_counter == 2) 788512430eSIlpo Järvinen tp->frto_counter = 3; 7966f5fe62SIlpo Järvinen 8066f5fe62SIlpo Järvinen tp->packets_out += tcp_skb_pcount(skb); 81*750ea2baSYuchung Cheng if (!prior_packets || tp->early_retrans_delayed) 82*750ea2baSYuchung Cheng tcp_rearm_rto(sk); 831da177e4SLinus Torvalds } 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 861da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 871da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 881da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 891da177e4SLinus Torvalds * invalid. OK, let's make this for now: 901da177e4SLinus Torvalds */ 91cf533ea5SEric Dumazet static inline __u32 tcp_acceptable_seq(const struct sock *sk) 921da177e4SLinus Torvalds { 93cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 949e412ba7SIlpo Järvinen 9590840defSIlpo Järvinen if (!before(tcp_wnd_end(tp), tp->snd_nxt)) 961da177e4SLinus Torvalds return tp->snd_nxt; 971da177e4SLinus Torvalds else 9890840defSIlpo Järvinen return tcp_wnd_end(tp); 991da177e4SLinus Torvalds } 1001da177e4SLinus Torvalds 1011da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1021da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1031da177e4SLinus Torvalds * 1041da177e4SLinus Torvalds * 1. It is independent of path mtu. 1051da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1061da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1071da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1081da177e4SLinus Torvalds * large MSS. 1091da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1101da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1111da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1121da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1131da177e4SLinus Torvalds * probably even Jumbo". 1141da177e4SLinus Torvalds */ 1151da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1161da177e4SLinus Torvalds { 1171da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 118cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1191da177e4SLinus Torvalds int mss = tp->advmss; 1201da177e4SLinus Torvalds 1210dbaee3bSDavid S. Miller if (dst) { 1220dbaee3bSDavid S. Miller unsigned int metric = dst_metric_advmss(dst); 1230dbaee3bSDavid S. Miller 1240dbaee3bSDavid S. Miller if (metric < mss) { 1250dbaee3bSDavid S. Miller mss = metric; 1261da177e4SLinus Torvalds tp->advmss = mss; 1271da177e4SLinus Torvalds } 1280dbaee3bSDavid S. Miller } 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds return (__u16)mss; 1311da177e4SLinus Torvalds } 1321da177e4SLinus Torvalds 1331da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1341da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 135cf533ea5SEric Dumazet static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst) 1361da177e4SLinus Torvalds { 137463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1381da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1391da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1401da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1411da177e4SLinus Torvalds 1426687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1431da177e4SLinus Torvalds 1446687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1451da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1461da177e4SLinus Torvalds 147463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1481da177e4SLinus Torvalds cwnd >>= 1; 1491da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1501da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1511da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1521da177e4SLinus Torvalds } 1531da177e4SLinus Torvalds 15467edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 15540efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 156cf533ea5SEric Dumazet struct sock *sk) 1571da177e4SLinus Torvalds { 158463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 159463c84b9SArnaldo Carvalho de Melo const u32 now = tcp_time_stamp; 1601da177e4SLinus Torvalds 16135089bb2SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 16235089bb2SDavid S. Miller (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) 163463c84b9SArnaldo Carvalho de Melo tcp_cwnd_restart(sk, __sk_dst_get(sk)); 1641da177e4SLinus Torvalds 1651da177e4SLinus Torvalds tp->lsndtime = now; 1661da177e4SLinus Torvalds 1671da177e4SLinus Torvalds /* If it is a reply for ato after last received 1681da177e4SLinus Torvalds * packet, enter pingpong mode. 1691da177e4SLinus Torvalds */ 170463c84b9SArnaldo Carvalho de Melo if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 171463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1721da177e4SLinus Torvalds } 1731da177e4SLinus Torvalds 17467edfef7SAndi Kleen /* Account for an ACK we sent. */ 17540efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1761da177e4SLinus Torvalds { 177463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 178463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1791da177e4SLinus Torvalds } 1801da177e4SLinus Torvalds 1811da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 1821da177e4SLinus Torvalds * Based on the assumption that the given amount of space 1831da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 1841da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 1851da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 1861da177e4SLinus Torvalds * This MUST be enforced by all callers. 1871da177e4SLinus Torvalds */ 1881da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 1891da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 19031d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 19131d12926Slaurent chavey __u32 init_rcv_wnd) 1921da177e4SLinus Torvalds { 1931da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 1941da177e4SLinus Torvalds 1951da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 1961da177e4SLinus Torvalds if (*window_clamp == 0) 1971da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 1981da177e4SLinus Torvalds space = min(*window_clamp, space); 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 2011da177e4SLinus Torvalds if (space > mss) 2021da177e4SLinus Torvalds space = (space / mss) * mss; 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 20515d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 20615d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 20715d99e02SRick Jones * we will truncate our initial window offering to 32K-1 20815d99e02SRick Jones * unless the remote has sent us a window scaling option, 20915d99e02SRick Jones * which we interpret as a sign the remote TCP is not 21015d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2111da177e4SLinus Torvalds */ 21215d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2131da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 21415d99e02SRick Jones else 21515d99e02SRick Jones (*rcv_wnd) = space; 21615d99e02SRick Jones 2171da177e4SLinus Torvalds (*rcv_wscale) = 0; 2181da177e4SLinus Torvalds if (wscale_ok) { 2191da177e4SLinus Torvalds /* Set window scaling on max possible window 2201da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 2211da177e4SLinus Torvalds */ 2221da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 223316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 2241da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 2251da177e4SLinus Torvalds space >>= 1; 2261da177e4SLinus Torvalds (*rcv_wscale)++; 2271da177e4SLinus Torvalds } 2281da177e4SLinus Torvalds } 2291da177e4SLinus Torvalds 230356f0398SNandita Dukkipati /* Set initial window to a value enough for senders starting with 231356f0398SNandita Dukkipati * initial congestion window of TCP_DEFAULT_INIT_RCVWND. Place 232356f0398SNandita Dukkipati * a limit on the initial window when mss is larger than 1460. 233356f0398SNandita Dukkipati */ 2341da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 235356f0398SNandita Dukkipati int init_cwnd = TCP_DEFAULT_INIT_RCVWND; 236356f0398SNandita Dukkipati if (mss > 1460) 237356f0398SNandita Dukkipati init_cwnd = 238356f0398SNandita Dukkipati max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2); 23931d12926Slaurent chavey /* when initializing use the value from init_rcv_wnd 24031d12926Slaurent chavey * rather than the default from above 24131d12926Slaurent chavey */ 242b1afde60SNandita Dukkipati if (init_rcv_wnd) 243b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); 244b1afde60SNandita Dukkipati else 245b1afde60SNandita Dukkipati *rcv_wnd = min(*rcv_wnd, init_cwnd * mss); 2461da177e4SLinus Torvalds } 2471da177e4SLinus Torvalds 2481da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2491da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2501da177e4SLinus Torvalds } 2514bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_select_initial_window); 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2541da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2551da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2561da177e4SLinus Torvalds * frame. 2571da177e4SLinus Torvalds */ 25840efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2591da177e4SLinus Torvalds { 2601da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2611da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2621da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds /* Never shrink the offered window */ 2651da177e4SLinus Torvalds if (new_win < cur_win) { 2661da177e4SLinus Torvalds /* Danger Will Robinson! 2671da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2681da177e4SLinus Torvalds * we will not be able to advertise a zero 2691da177e4SLinus Torvalds * window in time. --DaveM 2701da177e4SLinus Torvalds * 2711da177e4SLinus Torvalds * Relax Will Robinson. 2721da177e4SLinus Torvalds */ 273607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2741da177e4SLinus Torvalds } 2751da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2761da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2791da177e4SLinus Torvalds * scaled window. 2801da177e4SLinus Torvalds */ 28115d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2821da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2831da177e4SLinus Torvalds else 2841da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2851da177e4SLinus Torvalds 2861da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2871da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2881da177e4SLinus Torvalds 2891da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 2901da177e4SLinus Torvalds if (new_win == 0) 2911da177e4SLinus Torvalds tp->pred_flags = 0; 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds return new_win; 2941da177e4SLinus Torvalds } 2951da177e4SLinus Torvalds 29667edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 297cf533ea5SEric Dumazet static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb) 298bdf1ee5dSIlpo Järvinen { 2994de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; 300bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 3014de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; 302bdf1ee5dSIlpo Järvinen } 303bdf1ee5dSIlpo Järvinen 30467edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 305bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) 306bdf1ee5dSIlpo Järvinen { 307bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 308bdf1ee5dSIlpo Järvinen 309bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 310255cac91SIlpo Järvinen if (sysctl_tcp_ecn == 1) { 3114de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; 312bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 313bdf1ee5dSIlpo Järvinen } 314bdf1ee5dSIlpo Järvinen } 315bdf1ee5dSIlpo Järvinen 316bdf1ee5dSIlpo Järvinen static __inline__ void 317cf533ea5SEric Dumazet TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th) 318bdf1ee5dSIlpo Järvinen { 319bdf1ee5dSIlpo Järvinen if (inet_rsk(req)->ecn_ok) 320bdf1ee5dSIlpo Järvinen th->ece = 1; 321bdf1ee5dSIlpo Järvinen } 322bdf1ee5dSIlpo Järvinen 32367edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 32467edfef7SAndi Kleen * be sent. 32567edfef7SAndi Kleen */ 326bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, 327bdf1ee5dSIlpo Järvinen int tcp_header_len) 328bdf1ee5dSIlpo Järvinen { 329bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 330bdf1ee5dSIlpo Järvinen 331bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 332bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 333bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 334bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 335bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 336bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 337bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 338bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->cwr = 1; 339bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 340bdf1ee5dSIlpo Järvinen } 341bdf1ee5dSIlpo Järvinen } else { 342bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 343bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 344bdf1ee5dSIlpo Järvinen } 345bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 346bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->ece = 1; 347bdf1ee5dSIlpo Järvinen } 348bdf1ee5dSIlpo Järvinen } 349bdf1ee5dSIlpo Järvinen 350e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 351e870a8efSIlpo Järvinen * auto increment end seqno. 352e870a8efSIlpo Järvinen */ 353e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 354e870a8efSIlpo Järvinen { 3552e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 356e870a8efSIlpo Järvinen skb->csum = 0; 357e870a8efSIlpo Järvinen 3584de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags; 359e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 360e870a8efSIlpo Järvinen 361e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_segs = 1; 362e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_size = 0; 363e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_type = 0; 364e870a8efSIlpo Järvinen 365e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 366a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 367e870a8efSIlpo Järvinen seq++; 368e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 369e870a8efSIlpo Järvinen } 370e870a8efSIlpo Järvinen 37133f5f57eSIlpo Järvinen static inline int tcp_urg_mode(const struct tcp_sock *tp) 37233f5f57eSIlpo Järvinen { 37333f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 37433f5f57eSIlpo Järvinen } 37533f5f57eSIlpo Järvinen 37633ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 37733ad798cSAdam Langley #define OPTION_TS (1 << 1) 37833ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 37989e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 380bd0388aeSWilliam Allen Simpson #define OPTION_COOKIE_EXTENSION (1 << 4) 38133ad798cSAdam Langley 38233ad798cSAdam Langley struct tcp_out_options { 38333ad798cSAdam Langley u8 options; /* bit field of OPTION_* */ 38433ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 38533ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 386bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 38733ad798cSAdam Langley u16 mss; /* 0 to disable */ 38833ad798cSAdam Langley __u32 tsval, tsecr; /* need to include OPTION_TS */ 389bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 39033ad798cSAdam Langley }; 39133ad798cSAdam Langley 392bd0388aeSWilliam Allen Simpson /* The sysctl int routines are generic, so check consistency here. 393bd0388aeSWilliam Allen Simpson */ 394bd0388aeSWilliam Allen Simpson static u8 tcp_cookie_size_check(u8 desired) 395bd0388aeSWilliam Allen Simpson { 396f1987257SEric Dumazet int cookie_size; 397f1987257SEric Dumazet 398f1987257SEric Dumazet if (desired > 0) 399bd0388aeSWilliam Allen Simpson /* previously specified */ 400bd0388aeSWilliam Allen Simpson return desired; 401f1987257SEric Dumazet 402f1987257SEric Dumazet cookie_size = ACCESS_ONCE(sysctl_tcp_cookie_size); 403f1987257SEric Dumazet if (cookie_size <= 0) 404bd0388aeSWilliam Allen Simpson /* no default specified */ 405bd0388aeSWilliam Allen Simpson return 0; 406f1987257SEric Dumazet 407f1987257SEric Dumazet if (cookie_size <= TCP_COOKIE_MIN) 408bd0388aeSWilliam Allen Simpson /* value too small, specify minimum */ 409bd0388aeSWilliam Allen Simpson return TCP_COOKIE_MIN; 410f1987257SEric Dumazet 411f1987257SEric Dumazet if (cookie_size >= TCP_COOKIE_MAX) 412bd0388aeSWilliam Allen Simpson /* value too large, specify maximum */ 413bd0388aeSWilliam Allen Simpson return TCP_COOKIE_MAX; 414f1987257SEric Dumazet 415f1987257SEric Dumazet if (cookie_size & 1) 416bd0388aeSWilliam Allen Simpson /* 8-bit multiple, illegal, fix it */ 417f1987257SEric Dumazet cookie_size++; 418f1987257SEric Dumazet 419f1987257SEric Dumazet return (u8)cookie_size; 420bd0388aeSWilliam Allen Simpson } 421bd0388aeSWilliam Allen Simpson 42267edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 42367edfef7SAndi Kleen * 42467edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 425fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 426fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 427fd6149d3SIlpo Järvinen * inter-operatibility perspective it seems that we're somewhat stuck with 428fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 429fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 430fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 431fd6149d3SIlpo Järvinen * 432fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 433fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 434fd6149d3SIlpo Järvinen */ 43533ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 436bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 437bd0388aeSWilliam Allen Simpson { 438bd0388aeSWilliam Allen Simpson u8 options = opts->options; /* mungable copy */ 439bd0388aeSWilliam Allen Simpson 440bd0388aeSWilliam Allen Simpson /* Having both authentication and cookies for security is redundant, 441bd0388aeSWilliam Allen Simpson * and there's certainly not enough room. Instead, the cookie-less 442bd0388aeSWilliam Allen Simpson * extension variant is proposed. 443bd0388aeSWilliam Allen Simpson * 444bd0388aeSWilliam Allen Simpson * Consider the pessimal case with authentication. The options 445bd0388aeSWilliam Allen Simpson * could look like: 446bd0388aeSWilliam Allen Simpson * COOKIE|MD5(20) + MSS(4) + SACK|TS(12) + WSCALE(4) == 40 447bd0388aeSWilliam Allen Simpson */ 448bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 449bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_COOKIE_EXTENSION & options)) { 450bd0388aeSWilliam Allen Simpson *ptr++ = htonl((TCPOPT_COOKIE << 24) | 451bd0388aeSWilliam Allen Simpson (TCPOLEN_COOKIE_BASE << 16) | 452bd0388aeSWilliam Allen Simpson (TCPOPT_MD5SIG << 8) | 453bd0388aeSWilliam Allen Simpson TCPOLEN_MD5SIG); 454bd0388aeSWilliam Allen Simpson } else { 45533ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 45633ad798cSAdam Langley (TCPOPT_NOP << 16) | 45733ad798cSAdam Langley (TCPOPT_MD5SIG << 8) | 45833ad798cSAdam Langley TCPOLEN_MD5SIG); 459bd0388aeSWilliam Allen Simpson } 460bd0388aeSWilliam Allen Simpson options &= ~OPTION_COOKIE_EXTENSION; 461bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 462bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 46333ad798cSAdam Langley ptr += 4; 46433ad798cSAdam Langley } 46533ad798cSAdam Langley 466fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 467fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 468fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 469fd6149d3SIlpo Järvinen opts->mss); 470fd6149d3SIlpo Järvinen } 471fd6149d3SIlpo Järvinen 472bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 473bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 47433ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 47533ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 47633ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 47733ad798cSAdam Langley TCPOLEN_TIMESTAMP); 478bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 47933ad798cSAdam Langley } else { 480496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 48140efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 48240efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 48340efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 48440efc6faSStephen Hemminger } 48533ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 48633ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 48733ad798cSAdam Langley } 48833ad798cSAdam Langley 489bd0388aeSWilliam Allen Simpson /* Specification requires after timestamp, so do it now. 490bd0388aeSWilliam Allen Simpson * 491bd0388aeSWilliam Allen Simpson * Consider the pessimal case without authentication. The options 492bd0388aeSWilliam Allen Simpson * could look like: 493bd0388aeSWilliam Allen Simpson * MSS(4) + SACK|TS(12) + COOKIE(20) + WSCALE(4) == 40 494bd0388aeSWilliam Allen Simpson */ 495bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_COOKIE_EXTENSION & options)) { 496bd0388aeSWilliam Allen Simpson __u8 *cookie_copy = opts->hash_location; 497bd0388aeSWilliam Allen Simpson u8 cookie_size = opts->hash_size; 498bd0388aeSWilliam Allen Simpson 499bd0388aeSWilliam Allen Simpson /* 8-bit multiple handled in tcp_cookie_size_check() above, 500bd0388aeSWilliam Allen Simpson * and elsewhere. 501bd0388aeSWilliam Allen Simpson */ 502bd0388aeSWilliam Allen Simpson if (0x2 & cookie_size) { 503bd0388aeSWilliam Allen Simpson __u8 *p = (__u8 *)ptr; 504bd0388aeSWilliam Allen Simpson 505bd0388aeSWilliam Allen Simpson /* 16-bit multiple */ 506bd0388aeSWilliam Allen Simpson *p++ = TCPOPT_COOKIE; 507bd0388aeSWilliam Allen Simpson *p++ = TCPOLEN_COOKIE_BASE + cookie_size; 508bd0388aeSWilliam Allen Simpson *p++ = *cookie_copy++; 509bd0388aeSWilliam Allen Simpson *p++ = *cookie_copy++; 510bd0388aeSWilliam Allen Simpson ptr++; 511bd0388aeSWilliam Allen Simpson cookie_size -= 2; 512bd0388aeSWilliam Allen Simpson } else { 513bd0388aeSWilliam Allen Simpson /* 32-bit multiple */ 514bd0388aeSWilliam Allen Simpson *ptr++ = htonl(((TCPOPT_NOP << 24) | 515bd0388aeSWilliam Allen Simpson (TCPOPT_NOP << 16) | 516bd0388aeSWilliam Allen Simpson (TCPOPT_COOKIE << 8) | 517bd0388aeSWilliam Allen Simpson TCPOLEN_COOKIE_BASE) + 518bd0388aeSWilliam Allen Simpson cookie_size); 519bd0388aeSWilliam Allen Simpson } 520bd0388aeSWilliam Allen Simpson 521bd0388aeSWilliam Allen Simpson if (cookie_size > 0) { 522bd0388aeSWilliam Allen Simpson memcpy(ptr, cookie_copy, cookie_size); 523bd0388aeSWilliam Allen Simpson ptr += (cookie_size / 4); 524bd0388aeSWilliam Allen Simpson } 525bd0388aeSWilliam Allen Simpson } 526bd0388aeSWilliam Allen Simpson 527bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 52833ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 52933ad798cSAdam Langley (TCPOPT_NOP << 16) | 53033ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 53133ad798cSAdam Langley TCPOLEN_SACK_PERM); 53233ad798cSAdam Langley } 53333ad798cSAdam Langley 534bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 53533ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 53633ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 53733ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 53833ad798cSAdam Langley opts->ws); 53933ad798cSAdam Langley } 54033ad798cSAdam Langley 54133ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 54233ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 54333ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 54440efc6faSStephen Hemminger int this_sack; 54540efc6faSStephen Hemminger 54640efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 54740efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 54840efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 54933ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 55040efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5512de979bdSStephen Hemminger 55233ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 55333ad798cSAdam Langley ++this_sack) { 55440efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 55540efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 55640efc6faSStephen Hemminger } 5572de979bdSStephen Hemminger 55840efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 55940efc6faSStephen Hemminger } 56040efc6faSStephen Hemminger } 56140efc6faSStephen Hemminger 56267edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 56367edfef7SAndi Kleen * network wire format yet. 56467edfef7SAndi Kleen */ 56595c96174SEric Dumazet static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, 56633ad798cSAdam Langley struct tcp_out_options *opts, 567cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 568cf533ea5SEric Dumazet { 56933ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 570bd0388aeSWilliam Allen Simpson struct tcp_cookie_values *cvp = tp->cookie_values; 57195c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 572bd0388aeSWilliam Allen Simpson u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ? 573bd0388aeSWilliam Allen Simpson tcp_cookie_size_check(cvp->cookie_desired) : 574bd0388aeSWilliam Allen Simpson 0; 57533ad798cSAdam Langley 576cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 57733ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 57833ad798cSAdam Langley if (*md5) { 57933ad798cSAdam Langley opts->options |= OPTION_MD5; 580bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 581cfb6eeb4SYOSHIFUJI Hideaki } 58233ad798cSAdam Langley #else 58333ad798cSAdam Langley *md5 = NULL; 584cfb6eeb4SYOSHIFUJI Hideaki #endif 58533ad798cSAdam Langley 58633ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 58733ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 58833ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 58933ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 59033ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 59133ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 59233ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 59333ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 59433ad798cSAdam Langley * going out. */ 59533ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 596bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 59733ad798cSAdam Langley 598bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { 59933ad798cSAdam Langley opts->options |= OPTION_TS; 60033ad798cSAdam Langley opts->tsval = TCP_SKB_CB(skb)->when; 60133ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 602bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 60333ad798cSAdam Langley } 604bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_window_scaling)) { 60533ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 60689e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 607bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 60833ad798cSAdam Langley } 609bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_sack)) { 61033ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 611b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 612bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 61333ad798cSAdam Langley } 61433ad798cSAdam Langley 615bd0388aeSWilliam Allen Simpson /* Note that timestamps are required by the specification. 616bd0388aeSWilliam Allen Simpson * 617bd0388aeSWilliam Allen Simpson * Odd numbers of bytes are prohibited by the specification, ensuring 618bd0388aeSWilliam Allen Simpson * that the cookie is 16-bit aligned, and the resulting cookie pair is 619bd0388aeSWilliam Allen Simpson * 32-bit aligned. 620bd0388aeSWilliam Allen Simpson */ 621bd0388aeSWilliam Allen Simpson if (*md5 == NULL && 622bd0388aeSWilliam Allen Simpson (OPTION_TS & opts->options) && 623bd0388aeSWilliam Allen Simpson cookie_size > 0) { 624bd0388aeSWilliam Allen Simpson int need = TCPOLEN_COOKIE_BASE + cookie_size; 625bd0388aeSWilliam Allen Simpson 626bd0388aeSWilliam Allen Simpson if (0x2 & need) { 627bd0388aeSWilliam Allen Simpson /* 32-bit multiple */ 628bd0388aeSWilliam Allen Simpson need += 2; /* NOPs */ 629bd0388aeSWilliam Allen Simpson 630bd0388aeSWilliam Allen Simpson if (need > remaining) { 631bd0388aeSWilliam Allen Simpson /* try shrinking cookie to fit */ 632bd0388aeSWilliam Allen Simpson cookie_size -= 2; 633bd0388aeSWilliam Allen Simpson need -= 4; 634bd0388aeSWilliam Allen Simpson } 635bd0388aeSWilliam Allen Simpson } 636bd0388aeSWilliam Allen Simpson while (need > remaining && TCP_COOKIE_MIN <= cookie_size) { 637bd0388aeSWilliam Allen Simpson cookie_size -= 4; 638bd0388aeSWilliam Allen Simpson need -= 4; 639bd0388aeSWilliam Allen Simpson } 640bd0388aeSWilliam Allen Simpson if (TCP_COOKIE_MIN <= cookie_size) { 641bd0388aeSWilliam Allen Simpson opts->options |= OPTION_COOKIE_EXTENSION; 642bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)&cvp->cookie_pair[0]; 643bd0388aeSWilliam Allen Simpson opts->hash_size = cookie_size; 644bd0388aeSWilliam Allen Simpson 645bd0388aeSWilliam Allen Simpson /* Remember for future incarnations. */ 646bd0388aeSWilliam Allen Simpson cvp->cookie_desired = cookie_size; 647bd0388aeSWilliam Allen Simpson 648bd0388aeSWilliam Allen Simpson if (cvp->cookie_desired != cvp->cookie_pair_size) { 649bd0388aeSWilliam Allen Simpson /* Currently use random bytes as a nonce, 650bd0388aeSWilliam Allen Simpson * assuming these are completely unpredictable 651bd0388aeSWilliam Allen Simpson * by hostile users of the same system. 652bd0388aeSWilliam Allen Simpson */ 653bd0388aeSWilliam Allen Simpson get_random_bytes(&cvp->cookie_pair[0], 654bd0388aeSWilliam Allen Simpson cookie_size); 655bd0388aeSWilliam Allen Simpson cvp->cookie_pair_size = cookie_size; 656bd0388aeSWilliam Allen Simpson } 657bd0388aeSWilliam Allen Simpson 658bd0388aeSWilliam Allen Simpson remaining -= need; 659bd0388aeSWilliam Allen Simpson } 660bd0388aeSWilliam Allen Simpson } 661bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 66233ad798cSAdam Langley } 66333ad798cSAdam Langley 66467edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 66595c96174SEric Dumazet static unsigned int tcp_synack_options(struct sock *sk, 66633ad798cSAdam Langley struct request_sock *req, 66795c96174SEric Dumazet unsigned int mss, struct sk_buff *skb, 66833ad798cSAdam Langley struct tcp_out_options *opts, 6694957faadSWilliam Allen Simpson struct tcp_md5sig_key **md5, 6704957faadSWilliam Allen Simpson struct tcp_extend_values *xvp) 6714957faadSWilliam Allen Simpson { 67233ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 67395c96174SEric Dumazet unsigned int remaining = MAX_TCP_OPTION_SPACE; 6744957faadSWilliam Allen Simpson u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ? 6754957faadSWilliam Allen Simpson xvp->cookie_plus : 6764957faadSWilliam Allen Simpson 0; 67733ad798cSAdam Langley 67833ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 67933ad798cSAdam Langley *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); 68033ad798cSAdam Langley if (*md5) { 68133ad798cSAdam Langley opts->options |= OPTION_MD5; 6824957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6834957faadSWilliam Allen Simpson 6844957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6854957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6864957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6874957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6884957faadSWilliam Allen Simpson */ 689de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 69033ad798cSAdam Langley } 69133ad798cSAdam Langley #else 69233ad798cSAdam Langley *md5 = NULL; 69333ad798cSAdam Langley #endif 69433ad798cSAdam Langley 6954957faadSWilliam Allen Simpson /* We always send an MSS option. */ 69633ad798cSAdam Langley opts->mss = mss; 6974957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 69833ad798cSAdam Langley 69933ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 70033ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 70189e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 7024957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 70333ad798cSAdam Langley } 704de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 70533ad798cSAdam Langley opts->options |= OPTION_TS; 70633ad798cSAdam Langley opts->tsval = TCP_SKB_CB(skb)->when; 70733ad798cSAdam Langley opts->tsecr = req->ts_recent; 7084957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 70933ad798cSAdam Langley } 71033ad798cSAdam Langley if (likely(ireq->sack_ok)) { 71133ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 712de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 7134957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 71433ad798cSAdam Langley } 71533ad798cSAdam Langley 7164957faadSWilliam Allen Simpson /* Similar rationale to tcp_syn_options() applies here, too. 7174957faadSWilliam Allen Simpson * If the <SYN> options fit, the same options should fit now! 7184957faadSWilliam Allen Simpson */ 7194957faadSWilliam Allen Simpson if (*md5 == NULL && 720de213e5eSEric Dumazet ireq->tstamp_ok && 7214957faadSWilliam Allen Simpson cookie_plus > TCPOLEN_COOKIE_BASE) { 7224957faadSWilliam Allen Simpson int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */ 7234957faadSWilliam Allen Simpson 7244957faadSWilliam Allen Simpson if (0x2 & need) { 7254957faadSWilliam Allen Simpson /* 32-bit multiple */ 7264957faadSWilliam Allen Simpson need += 2; /* NOPs */ 7274957faadSWilliam Allen Simpson } 7284957faadSWilliam Allen Simpson if (need <= remaining) { 7294957faadSWilliam Allen Simpson opts->options |= OPTION_COOKIE_EXTENSION; 7304957faadSWilliam Allen Simpson opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE; 7314957faadSWilliam Allen Simpson remaining -= need; 7324957faadSWilliam Allen Simpson } else { 7334957faadSWilliam Allen Simpson /* There's no error return, so flag it. */ 7344957faadSWilliam Allen Simpson xvp->cookie_out_never = 1; /* true */ 7354957faadSWilliam Allen Simpson opts->hash_size = 0; 7364957faadSWilliam Allen Simpson } 7374957faadSWilliam Allen Simpson } 7384957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 73933ad798cSAdam Langley } 74033ad798cSAdam Langley 74167edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 74267edfef7SAndi Kleen * final wire format yet. 74367edfef7SAndi Kleen */ 74495c96174SEric Dumazet static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, 74533ad798cSAdam Langley struct tcp_out_options *opts, 746cf533ea5SEric Dumazet struct tcp_md5sig_key **md5) 747cf533ea5SEric Dumazet { 74833ad798cSAdam Langley struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; 74933ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 75095c96174SEric Dumazet unsigned int size = 0; 751cabeccbdSIlpo Järvinen unsigned int eff_sacks; 75233ad798cSAdam Langley 75333ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 75433ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 75533ad798cSAdam Langley if (unlikely(*md5)) { 75633ad798cSAdam Langley opts->options |= OPTION_MD5; 75733ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 75833ad798cSAdam Langley } 75933ad798cSAdam Langley #else 76033ad798cSAdam Langley *md5 = NULL; 76133ad798cSAdam Langley #endif 76233ad798cSAdam Langley 76333ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 76433ad798cSAdam Langley opts->options |= OPTION_TS; 76533ad798cSAdam Langley opts->tsval = tcb ? tcb->when : 0; 76633ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 76733ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 76833ad798cSAdam Langley } 76933ad798cSAdam Langley 770cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 771cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 77295c96174SEric Dumazet const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; 77333ad798cSAdam Langley opts->num_sack_blocks = 77495c96174SEric Dumazet min_t(unsigned int, eff_sacks, 77533ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 77633ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 77733ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 77833ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 77933ad798cSAdam Langley } 78033ad798cSAdam Langley 78133ad798cSAdam Langley return size; 78240efc6faSStephen Hemminger } 7831da177e4SLinus Torvalds 7841da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 7851da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 7861da177e4SLinus Torvalds * transmission and possible later retransmissions. 7871da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 7881da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 7891da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 7901da177e4SLinus Torvalds * device. 7911da177e4SLinus Torvalds * 7921da177e4SLinus Torvalds * We are working here with either a clone of the original 7931da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 7941da177e4SLinus Torvalds */ 795056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 796056834d9SIlpo Järvinen gfp_t gfp_mask) 7971da177e4SLinus Torvalds { 7986687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 799dfb4b9dcSDavid S. Miller struct inet_sock *inet; 800dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 801dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 80233ad798cSAdam Langley struct tcp_out_options opts; 80395c96174SEric Dumazet unsigned int tcp_options_size, tcp_header_size; 804cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 8051da177e4SLinus Torvalds struct tcphdr *th; 8061da177e4SLinus Torvalds int err; 8071da177e4SLinus Torvalds 808dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 809dfb4b9dcSDavid S. Miller 810dfb4b9dcSDavid S. Miller /* If congestion control is doing timestamping, we must 811dfb4b9dcSDavid S. Miller * take such a timestamp before we potentially clone/copy. 812dfb4b9dcSDavid S. Miller */ 813164891aaSStephen Hemminger if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) 814dfb4b9dcSDavid S. Miller __net_timestamp(skb); 815dfb4b9dcSDavid S. Miller 816dfb4b9dcSDavid S. Miller if (likely(clone_it)) { 817dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 818dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 819dfb4b9dcSDavid S. Miller else 820dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 821dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 822dfb4b9dcSDavid S. Miller return -ENOBUFS; 823dfb4b9dcSDavid S. Miller } 824dfb4b9dcSDavid S. Miller 825dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 826dfb4b9dcSDavid S. Miller tp = tcp_sk(sk); 827dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 82833ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 8291da177e4SLinus Torvalds 8304de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) 83133ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 83233ad798cSAdam Langley else 83333ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 83433ad798cSAdam Langley &md5); 83533ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 8361da177e4SLinus Torvalds 8373853b584STom Herbert if (tcp_packets_in_flight(tp) == 0) { 8386687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_TX_START); 8393853b584STom Herbert skb->ooo_okay = 1; 8403853b584STom Herbert } else 8413853b584STom Herbert skb->ooo_okay = 0; 8421da177e4SLinus Torvalds 843aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 844aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 845e89862f4SDavid S. Miller skb_set_owner_w(skb, sk); 8461da177e4SLinus Torvalds 8471da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 848aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 849c720c7e8SEric Dumazet th->source = inet->inet_sport; 850c720c7e8SEric Dumazet th->dest = inet->inet_dport; 8511da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 8521da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 853df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 8544de075e0SEric Dumazet tcb->tcp_flags); 855dfb4b9dcSDavid S. Miller 8564de075e0SEric Dumazet if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { 8571da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 8581da177e4SLinus Torvalds * is never scaled. 8591da177e4SLinus Torvalds */ 860600ff0c2SIlpo Järvinen th->window = htons(min(tp->rcv_wnd, 65535U)); 8611da177e4SLinus Torvalds } else { 8621da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 8631da177e4SLinus Torvalds } 8641da177e4SLinus Torvalds th->check = 0; 8651da177e4SLinus Torvalds th->urg_ptr = 0; 8661da177e4SLinus Torvalds 86733f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 8687691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 8697691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 8701da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 8711da177e4SLinus Torvalds th->urg = 1; 8727691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 8730eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 8747691367dSHerbert Xu th->urg = 1; 8757691367dSHerbert Xu } 8761da177e4SLinus Torvalds } 8771da177e4SLinus Torvalds 878bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 8794de075e0SEric Dumazet if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0)) 8809e412ba7SIlpo Järvinen TCP_ECN_send(sk, skb, tcp_header_size); 881dfb4b9dcSDavid S. Miller 882cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 883cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 884cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 885a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 886bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 88749a72dfbSAdam Langley md5, sk, NULL, skb); 888cfb6eeb4SYOSHIFUJI Hideaki } 889cfb6eeb4SYOSHIFUJI Hideaki #endif 890cfb6eeb4SYOSHIFUJI Hideaki 891bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 8921da177e4SLinus Torvalds 8934de075e0SEric Dumazet if (likely(tcb->tcp_flags & TCPHDR_ACK)) 894fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 8951da177e4SLinus Torvalds 8961da177e4SLinus Torvalds if (skb->len != tcp_header_size) 897cf533ea5SEric Dumazet tcp_event_data_sent(tp, sk); 8981da177e4SLinus Torvalds 899bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 900aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 901aa2ea058STom Herbert tcp_skb_pcount(skb)); 9021da177e4SLinus Torvalds 903d9d8da80SDavid S. Miller err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl); 90483de47cdSHua Zhong if (likely(err <= 0)) 9051da177e4SLinus Torvalds return err; 9061da177e4SLinus Torvalds 9073cfe3baaSIlpo Järvinen tcp_enter_cwr(sk, 1); 9081da177e4SLinus Torvalds 909b9df3cb8SGerrit Renker return net_xmit_eval(err); 9101da177e4SLinus Torvalds } 9111da177e4SLinus Torvalds 91267edfef7SAndi Kleen /* This routine just queues the buffer for sending. 9131da177e4SLinus Torvalds * 9141da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 9151da177e4SLinus Torvalds * otherwise socket can stall. 9161da177e4SLinus Torvalds */ 9171da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 9181da177e4SLinus Torvalds { 9191da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 9201da177e4SLinus Torvalds 9211da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 9221da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 9231da177e4SLinus Torvalds skb_header_release(skb); 924fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 9253ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 9263ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 9271da177e4SLinus Torvalds } 9281da177e4SLinus Torvalds 92967edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 930cf533ea5SEric Dumazet static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, 931056834d9SIlpo Järvinen unsigned int mss_now) 932f6302d1dSDavid S. Miller { 9338e5b9ddaSHerbert Xu if (skb->len <= mss_now || !sk_can_gso(sk) || 9348e5b9ddaSHerbert Xu skb->ip_summed == CHECKSUM_NONE) { 935f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 936f6302d1dSDavid S. Miller * non-TSO case. 937f6302d1dSDavid S. Miller */ 9387967168cSHerbert Xu skb_shinfo(skb)->gso_segs = 1; 9397967168cSHerbert Xu skb_shinfo(skb)->gso_size = 0; 9407967168cSHerbert Xu skb_shinfo(skb)->gso_type = 0; 941f6302d1dSDavid S. Miller } else { 942356f89e1SIlpo Järvinen skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now); 9437967168cSHerbert Xu skb_shinfo(skb)->gso_size = mss_now; 944bcd76111SHerbert Xu skb_shinfo(skb)->gso_type = sk->sk_gso_type; 9451da177e4SLinus Torvalds } 9461da177e4SLinus Torvalds } 9471da177e4SLinus Torvalds 94891fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 94968f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 95091fed7a1SIlpo Järvinen */ 951cf533ea5SEric Dumazet static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb, 95291fed7a1SIlpo Järvinen int decr) 95391fed7a1SIlpo Järvinen { 954a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 955a47e5a98SIlpo Järvinen 956dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 95791fed7a1SIlpo Järvinen return; 95891fed7a1SIlpo Järvinen 9596859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 96091fed7a1SIlpo Järvinen tp->fackets_out -= decr; 96191fed7a1SIlpo Järvinen } 96291fed7a1SIlpo Järvinen 963797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 964797108d1SIlpo Järvinen * tweaks to fix counters 965797108d1SIlpo Järvinen */ 966cf533ea5SEric Dumazet static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) 967797108d1SIlpo Järvinen { 968797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 969797108d1SIlpo Järvinen 970797108d1SIlpo Järvinen tp->packets_out -= decr; 971797108d1SIlpo Järvinen 972797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 973797108d1SIlpo Järvinen tp->sacked_out -= decr; 974797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 975797108d1SIlpo Järvinen tp->retrans_out -= decr; 976797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 977797108d1SIlpo Järvinen tp->lost_out -= decr; 978797108d1SIlpo Järvinen 979797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 980797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 981797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 982797108d1SIlpo Järvinen 983797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 984797108d1SIlpo Järvinen 985797108d1SIlpo Järvinen if (tp->lost_skb_hint && 986797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 98752cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 988797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 989797108d1SIlpo Järvinen 990797108d1SIlpo Järvinen tcp_verify_left_out(tp); 991797108d1SIlpo Järvinen } 992797108d1SIlpo Järvinen 9931da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 9941da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 9951da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 9961da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 9971da177e4SLinus Torvalds */ 998056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 999056834d9SIlpo Järvinen unsigned int mss_now) 10001da177e4SLinus Torvalds { 10011da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10021da177e4SLinus Torvalds struct sk_buff *buff; 10036475be16SDavid S. Miller int nsize, old_factor; 1004b60b49eaSHerbert Xu int nlen; 10059ce01461SIlpo Järvinen u8 flags; 10061da177e4SLinus Torvalds 10072fceec13SIlpo Järvinen if (WARN_ON(len > skb->len)) 10082fceec13SIlpo Järvinen return -EINVAL; 10096a438bbeSStephen Hemminger 10101da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 10111da177e4SLinus Torvalds if (nsize < 0) 10121da177e4SLinus Torvalds nsize = 0; 10131da177e4SLinus Torvalds 10141da177e4SLinus Torvalds if (skb_cloned(skb) && 10151da177e4SLinus Torvalds skb_is_nonlinear(skb) && 10161da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 10171da177e4SLinus Torvalds return -ENOMEM; 10181da177e4SLinus Torvalds 10191da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 10201da177e4SLinus Torvalds buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); 10211da177e4SLinus Torvalds if (buff == NULL) 10221da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1023ef5cb973SHerbert Xu 10243ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 10253ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1026b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1027b60b49eaSHerbert Xu buff->truesize += nlen; 1028b60b49eaSHerbert Xu skb->truesize -= nlen; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds /* Correct the sequence numbers. */ 10311da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 10321da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 10331da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 10341da177e4SLinus Torvalds 10351da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 10364de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 10374de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 10384de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1039e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 10401da177e4SLinus Torvalds 104184fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 10421da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1043056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1044056834d9SIlpo Järvinen skb_put(buff, nsize), 10451da177e4SLinus Torvalds nsize, 0); 10461da177e4SLinus Torvalds 10471da177e4SLinus Torvalds skb_trim(skb, len); 10481da177e4SLinus Torvalds 10491da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 10501da177e4SLinus Torvalds } else { 105184fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 10521da177e4SLinus Torvalds skb_split(skb, buff, len); 10531da177e4SLinus Torvalds } 10541da177e4SLinus Torvalds 10551da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 10561da177e4SLinus Torvalds 10571da177e4SLinus Torvalds /* Looks stupid, but our code really uses when of 10581da177e4SLinus Torvalds * skbs, which it never sent before. --ANK 10591da177e4SLinus Torvalds */ 10601da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; 1061a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 10621da177e4SLinus Torvalds 10636475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 10646475be16SDavid S. Miller 10651da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 1066846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1067846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 10681da177e4SLinus Torvalds 10696475be16SDavid S. Miller /* If this packet has been sent out already, we must 10706475be16SDavid S. Miller * adjust the various packet counters. 10716475be16SDavid S. Miller */ 1072cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 10736475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 10746475be16SDavid S. Miller tcp_skb_pcount(buff); 10751da177e4SLinus Torvalds 1076797108d1SIlpo Järvinen if (diff) 1077797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 10781da177e4SLinus Torvalds } 10791da177e4SLinus Torvalds 10801da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1081f44b5271SDavid S. Miller skb_header_release(buff); 1082fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 10831da177e4SLinus Torvalds 10841da177e4SLinus Torvalds return 0; 10851da177e4SLinus Torvalds } 10861da177e4SLinus Torvalds 10871da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 10881da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 10891da177e4SLinus Torvalds * immediately discarded. 10901da177e4SLinus Torvalds */ 1091f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 10921da177e4SLinus Torvalds { 10931da177e4SLinus Torvalds int i, k, eat; 10941da177e4SLinus Torvalds 10954fa48bf3SEric Dumazet eat = min_t(int, len, skb_headlen(skb)); 10964fa48bf3SEric Dumazet if (eat) { 10974fa48bf3SEric Dumazet __skb_pull(skb, eat); 109822b4a4f2SEric Dumazet skb->avail_size -= eat; 10994fa48bf3SEric Dumazet len -= eat; 11004fa48bf3SEric Dumazet if (!len) 11014fa48bf3SEric Dumazet return; 11024fa48bf3SEric Dumazet } 11031da177e4SLinus Torvalds eat = len; 11041da177e4SLinus Torvalds k = 0; 11051da177e4SLinus Torvalds for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 11069e903e08SEric Dumazet int size = skb_frag_size(&skb_shinfo(skb)->frags[i]); 11079e903e08SEric Dumazet 11089e903e08SEric Dumazet if (size <= eat) { 1109aff65da0SIan Campbell skb_frag_unref(skb, i); 11109e903e08SEric Dumazet eat -= size; 11111da177e4SLinus Torvalds } else { 11121da177e4SLinus Torvalds skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 11131da177e4SLinus Torvalds if (eat) { 11141da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].page_offset += eat; 11159e903e08SEric Dumazet skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat); 11161da177e4SLinus Torvalds eat = 0; 11171da177e4SLinus Torvalds } 11181da177e4SLinus Torvalds k++; 11191da177e4SLinus Torvalds } 11201da177e4SLinus Torvalds } 11211da177e4SLinus Torvalds skb_shinfo(skb)->nr_frags = k; 11221da177e4SLinus Torvalds 112327a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 11241da177e4SLinus Torvalds skb->data_len -= len; 11251da177e4SLinus Torvalds skb->len = skb->data_len; 11261da177e4SLinus Torvalds } 11271da177e4SLinus Torvalds 112867edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 11291da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 11301da177e4SLinus Torvalds { 1131056834d9SIlpo Järvinen if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 11321da177e4SLinus Torvalds return -ENOMEM; 11331da177e4SLinus Torvalds 11344fa48bf3SEric Dumazet __pskb_trim_head(skb, len); 11351da177e4SLinus Torvalds 11361da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 113784fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 11381da177e4SLinus Torvalds 11391da177e4SLinus Torvalds skb->truesize -= len; 11401da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 11413ab224beSHideo Aoki sk_mem_uncharge(sk, len); 11421da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 11431da177e4SLinus Torvalds 11445b35e1e6SNeal Cardwell /* Any change of skb->len requires recalculation of tso factor. */ 11451da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 11465b35e1e6SNeal Cardwell tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb)); 11471da177e4SLinus Torvalds 11481da177e4SLinus Torvalds return 0; 11491da177e4SLinus Torvalds } 11501da177e4SLinus Torvalds 115167edfef7SAndi Kleen /* Calculate MSS. Not accounting for SACKs here. */ 115267469601SEric Dumazet int tcp_mtu_to_mss(struct sock *sk, int pmtu) 11535d424d5aSJohn Heffner { 1154cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1155cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 11565d424d5aSJohn Heffner int mss_now; 11575d424d5aSJohn Heffner 11585d424d5aSJohn Heffner /* Calculate base mss without TCP options: 11595d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 11605d424d5aSJohn Heffner */ 11615d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 11625d424d5aSJohn Heffner 116367469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 116467469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 116567469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 116667469601SEric Dumazet 116767469601SEric Dumazet if (dst && dst_allfrag(dst)) 116867469601SEric Dumazet mss_now -= icsk->icsk_af_ops->net_frag_header_len; 116967469601SEric Dumazet } 117067469601SEric Dumazet 11715d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 11725d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 11735d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 11745d424d5aSJohn Heffner 11755d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 11765d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 11775d424d5aSJohn Heffner 11785d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 11795d424d5aSJohn Heffner if (mss_now < 48) 11805d424d5aSJohn Heffner mss_now = 48; 11815d424d5aSJohn Heffner 11825d424d5aSJohn Heffner /* Now subtract TCP options size, not including SACKs */ 11835d424d5aSJohn Heffner mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); 11845d424d5aSJohn Heffner 11855d424d5aSJohn Heffner return mss_now; 11865d424d5aSJohn Heffner } 11875d424d5aSJohn Heffner 11885d424d5aSJohn Heffner /* Inverse of above */ 118967469601SEric Dumazet int tcp_mss_to_mtu(struct sock *sk, int mss) 11905d424d5aSJohn Heffner { 1191cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1192cf533ea5SEric Dumazet const struct inet_connection_sock *icsk = inet_csk(sk); 11935d424d5aSJohn Heffner int mtu; 11945d424d5aSJohn Heffner 11955d424d5aSJohn Heffner mtu = mss + 11965d424d5aSJohn Heffner tp->tcp_header_len + 11975d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 11985d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 11995d424d5aSJohn Heffner 120067469601SEric Dumazet /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ 120167469601SEric Dumazet if (icsk->icsk_af_ops->net_frag_header_len) { 120267469601SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 120367469601SEric Dumazet 120467469601SEric Dumazet if (dst && dst_allfrag(dst)) 120567469601SEric Dumazet mtu += icsk->icsk_af_ops->net_frag_header_len; 120667469601SEric Dumazet } 12075d424d5aSJohn Heffner return mtu; 12085d424d5aSJohn Heffner } 12095d424d5aSJohn Heffner 121067edfef7SAndi Kleen /* MTU probing init per socket */ 12115d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 12125d424d5aSJohn Heffner { 12135d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 12145d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 12155d424d5aSJohn Heffner 12165d424d5aSJohn Heffner icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; 12175d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 12185d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 12195d424d5aSJohn Heffner icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); 12205d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 12215d424d5aSJohn Heffner } 12224bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_mtup_init); 12235d424d5aSJohn Heffner 12241da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 12251da177e4SLinus Torvalds 12261da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 12271da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1230caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 12311da177e4SLinus Torvalds It also does not include TCP options. 12321da177e4SLinus Torvalds 1233d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 12341da177e4SLinus Torvalds 12351da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 12361da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 12371da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 12381da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 12391da177e4SLinus Torvalds 12401da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 12411da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 12421da177e4SLinus Torvalds 1243d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1244d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 12451da177e4SLinus Torvalds */ 12461da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 12471da177e4SLinus Torvalds { 12481da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1249d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 12505d424d5aSJohn Heffner int mss_now; 12511da177e4SLinus Torvalds 12525d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 12535d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 12541da177e4SLinus Torvalds 12555d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1256409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 12571da177e4SLinus Torvalds 12581da177e4SLinus Torvalds /* And store cached results */ 1259d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 12605d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 12615d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1262c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 12631da177e4SLinus Torvalds 12641da177e4SLinus Torvalds return mss_now; 12651da177e4SLinus Torvalds } 12664bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_sync_mss); 12671da177e4SLinus Torvalds 12681da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 12691da177e4SLinus Torvalds * and even PMTU discovery events into account. 12701da177e4SLinus Torvalds */ 12710c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 12721da177e4SLinus Torvalds { 1273cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1274cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 1275c1b4a7e6SDavid S. Miller u32 mss_now; 127695c96174SEric Dumazet unsigned int header_len; 127733ad798cSAdam Langley struct tcp_out_options opts; 127833ad798cSAdam Langley struct tcp_md5sig_key *md5; 12791da177e4SLinus Torvalds 1280c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1281c1b4a7e6SDavid S. Miller 12821da177e4SLinus Torvalds if (dst) { 12831da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1284d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 12851da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 12861da177e4SLinus Torvalds } 12871da177e4SLinus Torvalds 128833ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 128933ad798cSAdam Langley sizeof(struct tcphdr); 129033ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 129133ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 129233ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 129333ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 129433ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 129533ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 129633ad798cSAdam Langley mss_now -= delta; 129733ad798cSAdam Langley } 1298cfb6eeb4SYOSHIFUJI Hideaki 12991da177e4SLinus Torvalds return mss_now; 13001da177e4SLinus Torvalds } 13011da177e4SLinus Torvalds 1302a762a980SDavid S. Miller /* Congestion window validation. (RFC2861) */ 13039e412ba7SIlpo Järvinen static void tcp_cwnd_validate(struct sock *sk) 1304a762a980SDavid S. Miller { 13059e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1306a762a980SDavid S. Miller 1307d436d686SIlpo Järvinen if (tp->packets_out >= tp->snd_cwnd) { 1308a762a980SDavid S. Miller /* Network is feed fully. */ 1309a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1310a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1311a762a980SDavid S. Miller } else { 1312a762a980SDavid S. Miller /* Network starves. */ 1313a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1314a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1315a762a980SDavid S. Miller 131615d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 131715d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1318a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1319a762a980SDavid S. Miller } 1320a762a980SDavid S. Miller } 1321a762a980SDavid S. Miller 13220e3a4803SIlpo Järvinen /* Returns the portion of skb which can be sent right away without 13230e3a4803SIlpo Järvinen * introducing MSS oddities to segment boundaries. In rare cases where 13240e3a4803SIlpo Järvinen * mss_now != mss_cache, we will request caller to create a small skb 13250e3a4803SIlpo Järvinen * per input skb which could be mostly avoided here (if desired). 13265ea3a748SIlpo Järvinen * 13275ea3a748SIlpo Järvinen * We explicitly want to create a request for splitting write queue tail 13285ea3a748SIlpo Järvinen * to a small skb for Nagle purposes while avoiding unnecessary modulos, 13295ea3a748SIlpo Järvinen * thus all the complexity (cwnd_len is always MSS multiple which we 13305ea3a748SIlpo Järvinen * return whenever allowed by the other factors). Basically we need the 13315ea3a748SIlpo Järvinen * modulo only when the receiver window alone is the limiting factor or 13325ea3a748SIlpo Järvinen * when we would be allowed to send the split-due-to-Nagle skb fully. 13330e3a4803SIlpo Järvinen */ 1334cf533ea5SEric Dumazet static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb, 1335056834d9SIlpo Järvinen unsigned int mss_now, unsigned int cwnd) 1336c1b4a7e6SDavid S. Miller { 1337cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 13380e3a4803SIlpo Järvinen u32 needed, window, cwnd_len; 1339c1b4a7e6SDavid S. Miller 134090840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1341c1b4a7e6SDavid S. Miller cwnd_len = mss_now * cwnd; 13420e3a4803SIlpo Järvinen 13430e3a4803SIlpo Järvinen if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk))) 13440e3a4803SIlpo Järvinen return cwnd_len; 13450e3a4803SIlpo Järvinen 13465ea3a748SIlpo Järvinen needed = min(skb->len, window); 13475ea3a748SIlpo Järvinen 134817515408SIlpo Järvinen if (cwnd_len <= needed) 13490e3a4803SIlpo Järvinen return cwnd_len; 13500e3a4803SIlpo Järvinen 13510e3a4803SIlpo Järvinen return needed - needed % mss_now; 1352c1b4a7e6SDavid S. Miller } 1353c1b4a7e6SDavid S. Miller 1354c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1355c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1356c1b4a7e6SDavid S. Miller */ 1357cf533ea5SEric Dumazet static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, 1358cf533ea5SEric Dumazet const struct sk_buff *skb) 1359c1b4a7e6SDavid S. Miller { 1360c1b4a7e6SDavid S. Miller u32 in_flight, cwnd; 1361c1b4a7e6SDavid S. Miller 1362c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 13634de075e0SEric Dumazet if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 13644de075e0SEric Dumazet tcp_skb_pcount(skb) == 1) 1365c1b4a7e6SDavid S. Miller return 1; 1366c1b4a7e6SDavid S. Miller 1367c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1368c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1369c1b4a7e6SDavid S. Miller if (in_flight < cwnd) 1370c1b4a7e6SDavid S. Miller return (cwnd - in_flight); 1371c1b4a7e6SDavid S. Miller 1372c1b4a7e6SDavid S. Miller return 0; 1373c1b4a7e6SDavid S. Miller } 1374c1b4a7e6SDavid S. Miller 1375b595076aSUwe Kleine-König /* Initialize TSO state of a skb. 137667edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1377c1b4a7e6SDavid S. Miller * SKB onto the wire. 1378c1b4a7e6SDavid S. Miller */ 1379cf533ea5SEric Dumazet static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb, 1380056834d9SIlpo Järvinen unsigned int mss_now) 1381c1b4a7e6SDavid S. Miller { 1382c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1383c1b4a7e6SDavid S. Miller 1384f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 1385846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1386c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1387c1b4a7e6SDavid S. Miller } 1388c1b4a7e6SDavid S. Miller return tso_segs; 1389c1b4a7e6SDavid S. Miller } 1390c1b4a7e6SDavid S. Miller 139167edfef7SAndi Kleen /* Minshall's variant of the Nagle send check. */ 1392c1b4a7e6SDavid S. Miller static inline int tcp_minshall_check(const struct tcp_sock *tp) 1393c1b4a7e6SDavid S. Miller { 1394c1b4a7e6SDavid S. Miller return after(tp->snd_sml, tp->snd_una) && 1395c1b4a7e6SDavid S. Miller !after(tp->snd_sml, tp->snd_nxt); 1396c1b4a7e6SDavid S. Miller } 1397c1b4a7e6SDavid S. Miller 1398c1b4a7e6SDavid S. Miller /* Return 0, if packet can be sent now without violation Nagle's rules: 1399c1b4a7e6SDavid S. Miller * 1. It is full sized. 1400c1b4a7e6SDavid S. Miller * 2. Or it contains FIN. (already checked by caller) 14016d67e9beSFeng King * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. 1402c1b4a7e6SDavid S. Miller * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1403c1b4a7e6SDavid S. Miller * With Minshall's modification: all sent small packets are ACKed. 1404c1b4a7e6SDavid S. Miller */ 1405c1b4a7e6SDavid S. Miller static inline int tcp_nagle_check(const struct tcp_sock *tp, 1406c1b4a7e6SDavid S. Miller const struct sk_buff *skb, 140795c96174SEric Dumazet unsigned int mss_now, int nonagle) 1408c1b4a7e6SDavid S. Miller { 1409a02cec21SEric Dumazet return skb->len < mss_now && 1410c1b4a7e6SDavid S. Miller ((nonagle & TCP_NAGLE_CORK) || 1411a02cec21SEric Dumazet (!nonagle && tp->packets_out && tcp_minshall_check(tp))); 1412c1b4a7e6SDavid S. Miller } 1413c1b4a7e6SDavid S. Miller 1414c1b4a7e6SDavid S. Miller /* Return non-zero if the Nagle test allows this packet to be 1415c1b4a7e6SDavid S. Miller * sent now. 1416c1b4a7e6SDavid S. Miller */ 1417cf533ea5SEric Dumazet static inline int tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1418c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1419c1b4a7e6SDavid S. Miller { 1420c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1421c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1422c1b4a7e6SDavid S. Miller * 1423c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1424c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1425c1b4a7e6SDavid S. Miller */ 1426c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1427c1b4a7e6SDavid S. Miller return 1; 1428c1b4a7e6SDavid S. Miller 1429d551e454SIlpo Järvinen /* Don't use the nagle rule for urgent data (or for the final FIN). 1430d551e454SIlpo Järvinen * Nagle can be ignored during F-RTO too (see RFC4138). 1431d551e454SIlpo Järvinen */ 143233f5f57eSIlpo Järvinen if (tcp_urg_mode(tp) || (tp->frto_counter == 2) || 14334de075e0SEric Dumazet (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) 1434c1b4a7e6SDavid S. Miller return 1; 1435c1b4a7e6SDavid S. Miller 1436c1b4a7e6SDavid S. Miller if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) 1437c1b4a7e6SDavid S. Miller return 1; 1438c1b4a7e6SDavid S. Miller 1439c1b4a7e6SDavid S. Miller return 0; 1440c1b4a7e6SDavid S. Miller } 1441c1b4a7e6SDavid S. Miller 1442c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1443cf533ea5SEric Dumazet static inline int tcp_snd_wnd_test(const struct tcp_sock *tp, const struct sk_buff *skb, 1444056834d9SIlpo Järvinen unsigned int cur_mss) 1445c1b4a7e6SDavid S. Miller { 1446c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1447c1b4a7e6SDavid S. Miller 1448c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1449c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1450c1b4a7e6SDavid S. Miller 145190840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1452c1b4a7e6SDavid S. Miller } 1453c1b4a7e6SDavid S. Miller 1454fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1455c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1456c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1457c1b4a7e6SDavid S. Miller */ 1458cf533ea5SEric Dumazet static unsigned int tcp_snd_test(const struct sock *sk, struct sk_buff *skb, 1459c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1460c1b4a7e6SDavid S. Miller { 1461cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1462c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1463c1b4a7e6SDavid S. Miller 1464846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 1465c1b4a7e6SDavid S. Miller 1466c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1467c1b4a7e6SDavid S. Miller return 0; 1468c1b4a7e6SDavid S. Miller 1469c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1470056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1471c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1472c1b4a7e6SDavid S. Miller 1473c1b4a7e6SDavid S. Miller return cwnd_quota; 1474c1b4a7e6SDavid S. Miller } 1475c1b4a7e6SDavid S. Miller 147667edfef7SAndi Kleen /* Test if sending is allowed right now. */ 14779e412ba7SIlpo Järvinen int tcp_may_send_now(struct sock *sk) 1478c1b4a7e6SDavid S. Miller { 1479cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 1480fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1481c1b4a7e6SDavid S. Miller 1482a02cec21SEric Dumazet return skb && 14830c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1484c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1485a02cec21SEric Dumazet tp->nonagle : TCP_NAGLE_PUSH)); 1486c1b4a7e6SDavid S. Miller } 1487c1b4a7e6SDavid S. Miller 1488c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1489c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1490c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1491c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1492c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1493c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1494c1b4a7e6SDavid S. Miller */ 1495056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1496c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1497c1b4a7e6SDavid S. Miller { 1498c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1499c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 15009ce01461SIlpo Järvinen u8 flags; 1501c1b4a7e6SDavid S. Miller 1502c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1503c8ac3774SHerbert Xu if (skb->len != skb->data_len) 1504c8ac3774SHerbert Xu return tcp_fragment(sk, skb, len, mss_now); 1505c1b4a7e6SDavid S. Miller 1506c4ead4c5SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp); 1507c1b4a7e6SDavid S. Miller if (unlikely(buff == NULL)) 1508c1b4a7e6SDavid S. Miller return -ENOMEM; 1509c1b4a7e6SDavid S. Miller 15103ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 15113ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1512b60b49eaSHerbert Xu buff->truesize += nlen; 1513c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1514c1b4a7e6SDavid S. Miller 1515c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1516c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1517c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1518c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1519c1b4a7e6SDavid S. Miller 1520c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 15214de075e0SEric Dumazet flags = TCP_SKB_CB(skb)->tcp_flags; 15224de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 15234de075e0SEric Dumazet TCP_SKB_CB(buff)->tcp_flags = flags; 1524c1b4a7e6SDavid S. Miller 1525c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1526c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1527c1b4a7e6SDavid S. Miller 152884fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1529c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1530c1b4a7e6SDavid S. Miller 1531c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 1532846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1533846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 1534c1b4a7e6SDavid S. Miller 1535c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1536c1b4a7e6SDavid S. Miller skb_header_release(buff); 1537fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1538c1b4a7e6SDavid S. Miller 1539c1b4a7e6SDavid S. Miller return 0; 1540c1b4a7e6SDavid S. Miller } 1541c1b4a7e6SDavid S. Miller 1542c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1543c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1544c1b4a7e6SDavid S. Miller * 1545c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1546c1b4a7e6SDavid S. Miller */ 15479e412ba7SIlpo Järvinen static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) 1548c1b4a7e6SDavid S. Miller { 15499e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 15506687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1551c1b4a7e6SDavid S. Miller u32 send_win, cong_win, limit, in_flight; 1552ad9f4f50SEric Dumazet int win_divisor; 1553c1b4a7e6SDavid S. Miller 15544de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) 1555ae8064acSJohn Heffner goto send_now; 1556c1b4a7e6SDavid S. Miller 15576687e988SArnaldo Carvalho de Melo if (icsk->icsk_ca_state != TCP_CA_Open) 1558ae8064acSJohn Heffner goto send_now; 1559ae8064acSJohn Heffner 1560ae8064acSJohn Heffner /* Defer for less than two clock ticks. */ 1561bd515c3eSIlpo Järvinen if (tp->tso_deferred && 1562a2acde07SIlpo Järvinen (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) 1563ae8064acSJohn Heffner goto send_now; 1564908a75c1SDavid S. Miller 1565c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1566c1b4a7e6SDavid S. Miller 1567056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1568c1b4a7e6SDavid S. Miller 156990840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1570c1b4a7e6SDavid S. Miller 1571c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1572c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1573c1b4a7e6SDavid S. Miller 1574c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1575c1b4a7e6SDavid S. Miller 1576ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 157782cc1a7aSPeter P Waskiewicz Jr if (limit >= sk->sk_gso_max_size) 1578ae8064acSJohn Heffner goto send_now; 1579ba244fe9SDavid S. Miller 158062ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 158162ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 158262ad2761SIlpo Järvinen goto send_now; 158362ad2761SIlpo Järvinen 1584ad9f4f50SEric Dumazet win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); 1585ad9f4f50SEric Dumazet if (win_divisor) { 1586c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1587c1b4a7e6SDavid S. Miller 1588c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1589c1b4a7e6SDavid S. Miller * just use it. 1590c1b4a7e6SDavid S. Miller */ 1591ad9f4f50SEric Dumazet chunk /= win_divisor; 1592c1b4a7e6SDavid S. Miller if (limit >= chunk) 1593ae8064acSJohn Heffner goto send_now; 1594c1b4a7e6SDavid S. Miller } else { 1595c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1596c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1597c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1598c1b4a7e6SDavid S. Miller * then send now. 1599c1b4a7e6SDavid S. Miller */ 16006b5a5c0dSNeal Cardwell if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) 1601ae8064acSJohn Heffner goto send_now; 1602c1b4a7e6SDavid S. Miller } 1603c1b4a7e6SDavid S. Miller 1604c1b4a7e6SDavid S. Miller /* Ok, it looks like it is advisable to defer. */ 1605ae8064acSJohn Heffner tp->tso_deferred = 1 | (jiffies << 1); 1606ae8064acSJohn Heffner 1607c1b4a7e6SDavid S. Miller return 1; 1608ae8064acSJohn Heffner 1609ae8064acSJohn Heffner send_now: 1610ae8064acSJohn Heffner tp->tso_deferred = 0; 1611ae8064acSJohn Heffner return 0; 1612c1b4a7e6SDavid S. Miller } 1613c1b4a7e6SDavid S. Miller 16145d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 161567edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 161667edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 161767edfef7SAndi Kleen * changes resulting in larger path MTUs. 161867edfef7SAndi Kleen * 16195d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 16205d424d5aSJohn Heffner * 1 if a probe was sent, 1621056834d9SIlpo Järvinen * -1 otherwise 1622056834d9SIlpo Järvinen */ 16235d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 16245d424d5aSJohn Heffner { 16255d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 16265d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 16275d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 16285d424d5aSJohn Heffner int len; 16295d424d5aSJohn Heffner int probe_size; 163091cc17c0SIlpo Järvinen int size_needed; 16315d424d5aSJohn Heffner int copy; 16325d424d5aSJohn Heffner int mss_now; 16335d424d5aSJohn Heffner 16345d424d5aSJohn Heffner /* Not currently probing/verifying, 16355d424d5aSJohn Heffner * not in recovery, 16365d424d5aSJohn Heffner * have enough cwnd, and 16375d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 16385d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 16395d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 16405d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 16415d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1642cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 16435d424d5aSJohn Heffner return -1; 16445d424d5aSJohn Heffner 16455d424d5aSJohn Heffner /* Very simple search strategy: just double the MSS. */ 16460c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 16475d424d5aSJohn Heffner probe_size = 2 * tp->mss_cache; 164891cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 16495d424d5aSJohn Heffner if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { 16505d424d5aSJohn Heffner /* TODO: set timer for probe_converge_event */ 16515d424d5aSJohn Heffner return -1; 16525d424d5aSJohn Heffner } 16535d424d5aSJohn Heffner 16545d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 16557f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 16565d424d5aSJohn Heffner return -1; 16575d424d5aSJohn Heffner 165891cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 16595d424d5aSJohn Heffner return -1; 166090840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 16615d424d5aSJohn Heffner return 0; 16625d424d5aSJohn Heffner 1663d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1664d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1665d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 16665d424d5aSJohn Heffner return -1; 16675d424d5aSJohn Heffner else 16685d424d5aSJohn Heffner return 0; 16695d424d5aSJohn Heffner } 16705d424d5aSJohn Heffner 16715d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 16725d424d5aSJohn Heffner if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) 16735d424d5aSJohn Heffner return -1; 16743ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 16753ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 16765d424d5aSJohn Heffner 1677fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 16785d424d5aSJohn Heffner 16795d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 16805d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 16814de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; 16825d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 16835d424d5aSJohn Heffner nskb->csum = 0; 168484fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 16855d424d5aSJohn Heffner 168650c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 168750c4817eSIlpo Järvinen 16885d424d5aSJohn Heffner len = 0; 1689234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 16905d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 16915d424d5aSJohn Heffner if (nskb->ip_summed) 16925d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 16935d424d5aSJohn Heffner else 16945d424d5aSJohn Heffner nskb->csum = skb_copy_and_csum_bits(skb, 0, 1695056834d9SIlpo Järvinen skb_put(nskb, copy), 1696056834d9SIlpo Järvinen copy, nskb->csum); 16975d424d5aSJohn Heffner 16985d424d5aSJohn Heffner if (skb->len <= copy) { 16995d424d5aSJohn Heffner /* We've eaten all the data from this skb. 17005d424d5aSJohn Heffner * Throw it away. */ 17014de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; 1702fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 17033ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 17045d424d5aSJohn Heffner } else { 17054de075e0SEric Dumazet TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & 1706a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 17075d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 17085d424d5aSJohn Heffner skb_pull(skb, copy); 170984fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 1710056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 1711056834d9SIlpo Järvinen skb->len, 0); 17125d424d5aSJohn Heffner } else { 17135d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 17145d424d5aSJohn Heffner tcp_set_skb_tso_segs(sk, skb, mss_now); 17155d424d5aSJohn Heffner } 17165d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 17175d424d5aSJohn Heffner } 17185d424d5aSJohn Heffner 17195d424d5aSJohn Heffner len += copy; 1720234b6860SIlpo Järvinen 1721234b6860SIlpo Järvinen if (len >= probe_size) 1722234b6860SIlpo Järvinen break; 17235d424d5aSJohn Heffner } 17245d424d5aSJohn Heffner tcp_init_tso_segs(sk, nskb, nskb->len); 17255d424d5aSJohn Heffner 17265d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 17275d424d5aSJohn Heffner * be resegmented into mss-sized pieces by tcp_write_xmit(). */ 17285d424d5aSJohn Heffner TCP_SKB_CB(nskb)->when = tcp_time_stamp; 17295d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 17305d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 17315d424d5aSJohn Heffner * effectively two packets. */ 17325d424d5aSJohn Heffner tp->snd_cwnd--; 173366f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 17345d424d5aSJohn Heffner 17355d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 17360e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 17370e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 17385d424d5aSJohn Heffner 17395d424d5aSJohn Heffner return 1; 17405d424d5aSJohn Heffner } 17415d424d5aSJohn Heffner 17425d424d5aSJohn Heffner return -1; 17435d424d5aSJohn Heffner } 17445d424d5aSJohn Heffner 17451da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 17461da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 17471da177e4SLinus Torvalds * window for us. 17481da177e4SLinus Torvalds * 1749f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 1750f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 1751f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 1752f8269a49SIlpo Järvinen * 17531da177e4SLinus Torvalds * Returns 1, if no segments are in flight and we have queued segments, but 17541da177e4SLinus Torvalds * cannot send anything now because of SWS or another problem. 17551da177e4SLinus Torvalds */ 1756d5dd9175SIlpo Järvinen static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 1757d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 17581da177e4SLinus Torvalds { 17591da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 176092df7b51SDavid S. Miller struct sk_buff *skb; 1761c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 1762c1b4a7e6SDavid S. Miller int cwnd_quota; 17635d424d5aSJohn Heffner int result; 17641da177e4SLinus Torvalds 1765c1b4a7e6SDavid S. Miller sent_pkts = 0; 17665d424d5aSJohn Heffner 1767d5dd9175SIlpo Järvinen if (!push_one) { 17685d424d5aSJohn Heffner /* Do MTU probing. */ 1769d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 1770d5dd9175SIlpo Järvinen if (!result) { 17715d424d5aSJohn Heffner return 0; 17725d424d5aSJohn Heffner } else if (result > 0) { 17735d424d5aSJohn Heffner sent_pkts = 1; 17745d424d5aSJohn Heffner } 1775d5dd9175SIlpo Järvinen } 17765d424d5aSJohn Heffner 1777fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 1778c8ac3774SHerbert Xu unsigned int limit; 1779c8ac3774SHerbert Xu 1780b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 1781c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 1782c1b4a7e6SDavid S. Miller 1783b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 1784b68e9f85SHerbert Xu if (!cwnd_quota) 1785b68e9f85SHerbert Xu break; 1786b68e9f85SHerbert Xu 1787b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 1788b68e9f85SHerbert Xu break; 1789b68e9f85SHerbert Xu 1790c1b4a7e6SDavid S. Miller if (tso_segs == 1) { 1791aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 1792aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1793aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 1794aa93466bSDavid S. Miller break; 1795c1b4a7e6SDavid S. Miller } else { 1796d5dd9175SIlpo Järvinen if (!push_one && tcp_tso_should_defer(sk, skb)) 1797aa93466bSDavid S. Miller break; 1798c1b4a7e6SDavid S. Miller } 1799aa93466bSDavid S. Miller 1800c8ac3774SHerbert Xu limit = mss_now; 1801f8269a49SIlpo Järvinen if (tso_segs > 1 && !tcp_urg_mode(tp)) 18020e3a4803SIlpo Järvinen limit = tcp_mss_split_point(sk, skb, mss_now, 18030e3a4803SIlpo Järvinen cwnd_quota); 1804c8ac3774SHerbert Xu 1805c8ac3774SHerbert Xu if (skb->len > limit && 1806c4ead4c5SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 18071da177e4SLinus Torvalds break; 18081da177e4SLinus Torvalds 18091da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 1810c1b4a7e6SDavid S. Miller 1811d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 18121da177e4SLinus Torvalds break; 18131da177e4SLinus Torvalds 18141da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 18151da177e4SLinus Torvalds * This call will increment packets_out. 18161da177e4SLinus Torvalds */ 181766f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 18181da177e4SLinus Torvalds 18191da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 1820a262f0cdSNandita Dukkipati sent_pkts += tcp_skb_pcount(skb); 1821d5dd9175SIlpo Järvinen 1822d5dd9175SIlpo Järvinen if (push_one) 1823d5dd9175SIlpo Järvinen break; 18241da177e4SLinus Torvalds } 1825a262f0cdSNandita Dukkipati if (inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery) 1826a262f0cdSNandita Dukkipati tp->prr_out += sent_pkts; 18271da177e4SLinus Torvalds 1828aa93466bSDavid S. Miller if (likely(sent_pkts)) { 18299e412ba7SIlpo Järvinen tcp_cwnd_validate(sk); 18301da177e4SLinus Torvalds return 0; 18311da177e4SLinus Torvalds } 1832fe067e8aSDavid S. Miller return !tp->packets_out && tcp_send_head(sk); 18331da177e4SLinus Torvalds } 18341da177e4SLinus Torvalds 1835a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 1836a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 1837a762a980SDavid S. Miller * The socket must be locked by the caller. 1838a762a980SDavid S. Miller */ 18399e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 18409e412ba7SIlpo Järvinen int nonagle) 1841a762a980SDavid S. Miller { 1842726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 1843726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 1844726e07a8SIlpo Järvinen * all will be happy. 1845726e07a8SIlpo Järvinen */ 1846726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 1847726e07a8SIlpo Järvinen return; 1848726e07a8SIlpo Järvinen 1849d5dd9175SIlpo Järvinen if (tcp_write_xmit(sk, cur_mss, nonagle, 0, GFP_ATOMIC)) 18509e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 1851a762a980SDavid S. Miller } 1852a762a980SDavid S. Miller 1853c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 1854c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 1855c1b4a7e6SDavid S. Miller */ 1856c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 1857c1b4a7e6SDavid S. Miller { 1858fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1859c1b4a7e6SDavid S. Miller 1860c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 1861c1b4a7e6SDavid S. Miller 1862d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 1863c1b4a7e6SDavid S. Miller } 1864c1b4a7e6SDavid S. Miller 18651da177e4SLinus Torvalds /* This function returns the amount that we can raise the 18661da177e4SLinus Torvalds * usable window based on the following constraints 18671da177e4SLinus Torvalds * 18681da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 18691da177e4SLinus Torvalds * 2. We limit memory per socket 18701da177e4SLinus Torvalds * 18711da177e4SLinus Torvalds * RFC 1122: 18721da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 18731da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 18741da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 18751da177e4SLinus Torvalds * 18761da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 18771da177e4SLinus Torvalds * it at least MSS bytes. 18781da177e4SLinus Torvalds * 18791da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 18801da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 18811da177e4SLinus Torvalds * 18821da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 18831da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 18841da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 18851da177e4SLinus Torvalds * window to always advance by a single byte. 18861da177e4SLinus Torvalds * 18871da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 18881da177e4SLinus Torvalds * then this will not be a problem. 18891da177e4SLinus Torvalds * 18901da177e4SLinus Torvalds * BSD seems to make the following compromise: 18911da177e4SLinus Torvalds * 18921da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 18931da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 18941da177e4SLinus Torvalds * then set the window to 0. 18951da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 18961da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 18971da177e4SLinus Torvalds * and from being larger than the largest representable value. 18981da177e4SLinus Torvalds * 18991da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 19001da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 19011da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 19021da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 19031da177e4SLinus Torvalds * because the pipeline is full. 19041da177e4SLinus Torvalds * 19051da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 19061da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 19071da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 19081da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 19091da177e4SLinus Torvalds * of having a fixed window size at almost all times. 19101da177e4SLinus Torvalds * 19111da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 19121da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 19131da177e4SLinus Torvalds * 19141da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 19151da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 19161da177e4SLinus Torvalds */ 19171da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 19181da177e4SLinus Torvalds { 1919463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 19201da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1921caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 19221da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 19231da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 19241da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 19251da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 19261da177e4SLinus Torvalds */ 1927463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 19281da177e4SLinus Torvalds int free_space = tcp_space(sk); 19291da177e4SLinus Torvalds int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); 19301da177e4SLinus Torvalds int window; 19311da177e4SLinus Torvalds 19321da177e4SLinus Torvalds if (mss > full_space) 19331da177e4SLinus Torvalds mss = full_space; 19341da177e4SLinus Torvalds 1935b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 1936463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 19371da177e4SLinus Torvalds 1938180d8cd9SGlauber Costa if (sk_under_memory_pressure(sk)) 1939056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 1940056834d9SIlpo Järvinen 4U * tp->advmss); 19411da177e4SLinus Torvalds 19421da177e4SLinus Torvalds if (free_space < mss) 19431da177e4SLinus Torvalds return 0; 19441da177e4SLinus Torvalds } 19451da177e4SLinus Torvalds 19461da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 19471da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 19481da177e4SLinus Torvalds 19491da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 19501da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 19511da177e4SLinus Torvalds */ 19521da177e4SLinus Torvalds window = tp->rcv_wnd; 19531da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 19541da177e4SLinus Torvalds window = free_space; 19551da177e4SLinus Torvalds 19561da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 19571da177e4SLinus Torvalds * Import case: prevent zero window announcement if 19581da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 19591da177e4SLinus Torvalds */ 19601da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 19611da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 19621da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 19631da177e4SLinus Torvalds } else { 19641da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 19651da177e4SLinus Torvalds * Window clamp already applied above. 19661da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 19671da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 19681da177e4SLinus Torvalds * and multiply from happening most of the time. 19691da177e4SLinus Torvalds * We also don't do any window rounding when the free space 19701da177e4SLinus Torvalds * is too small. 19711da177e4SLinus Torvalds */ 19721da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 19731da177e4SLinus Torvalds window = (free_space / mss) * mss; 197484565070SJohn Heffner else if (mss == full_space && 1975b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 197684565070SJohn Heffner window = free_space; 19771da177e4SLinus Torvalds } 19781da177e4SLinus Torvalds 19791da177e4SLinus Torvalds return window; 19801da177e4SLinus Torvalds } 19811da177e4SLinus Torvalds 19824a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 19834a17fc3aSIlpo Järvinen static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 19841da177e4SLinus Torvalds { 19851da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1986fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 1987058dc334SIlpo Järvinen int skb_size, next_skb_size; 19881da177e4SLinus Torvalds 1989058dc334SIlpo Järvinen skb_size = skb->len; 1990058dc334SIlpo Järvinen next_skb_size = next_skb->len; 19911da177e4SLinus Torvalds 1992058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 19931da177e4SLinus Torvalds 19946859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 1995a6963a6bSIlpo Järvinen 1996fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 19971da177e4SLinus Torvalds 1998058dc334SIlpo Järvinen skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), 19991a4e2d09SArnaldo Carvalho de Melo next_skb_size); 20001da177e4SLinus Torvalds 200152d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 200252d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 20031da177e4SLinus Torvalds 200484fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 20051da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 20061da177e4SLinus Torvalds 20071da177e4SLinus Torvalds /* Update sequence range on original skb. */ 20081da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 20091da177e4SLinus Torvalds 2010e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 20114de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; 20121da177e4SLinus Torvalds 20131da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 20141da177e4SLinus Torvalds * packet counting does not break. 20151da177e4SLinus Torvalds */ 20164828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 2017b7689205SIlpo Järvinen 2018b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 2019ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 2020ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 2021ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 2022b7689205SIlpo Järvinen 2023797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 2024797108d1SIlpo Järvinen 20253ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 20261da177e4SLinus Torvalds } 20271da177e4SLinus Torvalds 202867edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 2029cf533ea5SEric Dumazet static int tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) 20304a17fc3aSIlpo Järvinen { 20314a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 20324a17fc3aSIlpo Järvinen return 0; 20334a17fc3aSIlpo Järvinen /* TODO: SACK collapsing could be used to remove this condition */ 20344a17fc3aSIlpo Järvinen if (skb_shinfo(skb)->nr_frags != 0) 20354a17fc3aSIlpo Järvinen return 0; 20364a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 20374a17fc3aSIlpo Järvinen return 0; 20384a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 20394a17fc3aSIlpo Järvinen return 0; 20404a17fc3aSIlpo Järvinen /* Some heurestics for collapsing over SACK'd could be invented */ 20414a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 20424a17fc3aSIlpo Järvinen return 0; 20434a17fc3aSIlpo Järvinen 20444a17fc3aSIlpo Järvinen return 1; 20454a17fc3aSIlpo Järvinen } 20464a17fc3aSIlpo Järvinen 204767edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 204867edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 204967edfef7SAndi Kleen */ 20504a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 20514a17fc3aSIlpo Järvinen int space) 20524a17fc3aSIlpo Järvinen { 20534a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 20544a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 20554a17fc3aSIlpo Järvinen int first = 1; 20564a17fc3aSIlpo Järvinen 20574a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 20584a17fc3aSIlpo Järvinen return; 20594de075e0SEric Dumazet if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) 20604a17fc3aSIlpo Järvinen return; 20614a17fc3aSIlpo Järvinen 20624a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 20634a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 20644a17fc3aSIlpo Järvinen break; 20654a17fc3aSIlpo Järvinen 20664a17fc3aSIlpo Järvinen space -= skb->len; 20674a17fc3aSIlpo Järvinen 20684a17fc3aSIlpo Järvinen if (first) { 20694a17fc3aSIlpo Järvinen first = 0; 20704a17fc3aSIlpo Järvinen continue; 20714a17fc3aSIlpo Järvinen } 20724a17fc3aSIlpo Järvinen 20734a17fc3aSIlpo Järvinen if (space < 0) 20744a17fc3aSIlpo Järvinen break; 20754a17fc3aSIlpo Järvinen /* Punt if not enough space exists in the first SKB for 20764a17fc3aSIlpo Järvinen * the data in the second 20774a17fc3aSIlpo Järvinen */ 2078a21d4572SEric Dumazet if (skb->len > skb_availroom(to)) 20794a17fc3aSIlpo Järvinen break; 20804a17fc3aSIlpo Järvinen 20814a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 20824a17fc3aSIlpo Järvinen break; 20834a17fc3aSIlpo Järvinen 20844a17fc3aSIlpo Järvinen tcp_collapse_retrans(sk, to); 20854a17fc3aSIlpo Järvinen } 20864a17fc3aSIlpo Järvinen } 20874a17fc3aSIlpo Järvinen 20881da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 20891da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 20901da177e4SLinus Torvalds * error occurred which prevented the send. 20911da177e4SLinus Torvalds */ 20921da177e4SLinus Torvalds int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 20931da177e4SLinus Torvalds { 20941da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 20955d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 20967d227cd2SSridhar Samudrala unsigned int cur_mss; 20971da177e4SLinus Torvalds int err; 20981da177e4SLinus Torvalds 20995d424d5aSJohn Heffner /* Inconslusive MTU probe */ 21005d424d5aSJohn Heffner if (icsk->icsk_mtup.probe_size) { 21015d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 21025d424d5aSJohn Heffner } 21035d424d5aSJohn Heffner 21041da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2105caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 21061da177e4SLinus Torvalds */ 21071da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 21081da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 21091da177e4SLinus Torvalds return -EAGAIN; 21101da177e4SLinus Torvalds 21111da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 21121da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 21131da177e4SLinus Torvalds BUG(); 21141da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 21151da177e4SLinus Torvalds return -ENOMEM; 21161da177e4SLinus Torvalds } 21171da177e4SLinus Torvalds 21187d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 21197d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 21207d227cd2SSridhar Samudrala 21210c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 21227d227cd2SSridhar Samudrala 21231da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 21241da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 21251da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 21261da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 21271da177e4SLinus Torvalds */ 21289d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 21299d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 21301da177e4SLinus Torvalds return -EAGAIN; 21311da177e4SLinus Torvalds 21321da177e4SLinus Torvalds if (skb->len > cur_mss) { 2133846998aeSDavid S. Miller if (tcp_fragment(sk, skb, cur_mss, cur_mss)) 21341da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 213502276f3cSIlpo Järvinen } else { 21369eb9362eSIlpo Järvinen int oldpcount = tcp_skb_pcount(skb); 21379eb9362eSIlpo Järvinen 21389eb9362eSIlpo Järvinen if (unlikely(oldpcount > 1)) { 213902276f3cSIlpo Järvinen tcp_init_tso_segs(sk, skb, cur_mss); 21409eb9362eSIlpo Järvinen tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); 21419eb9362eSIlpo Järvinen } 21421da177e4SLinus Torvalds } 21431da177e4SLinus Torvalds 21441da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 21451da177e4SLinus Torvalds 21461da177e4SLinus Torvalds /* Some Solaris stacks overoptimize and ignore the FIN on a 21471da177e4SLinus Torvalds * retransmit when old data is attached. So strip it off 21481da177e4SLinus Torvalds * since it is cheap to do so and saves bytes on the network. 21491da177e4SLinus Torvalds */ 21501da177e4SLinus Torvalds if (skb->len > 0 && 21514de075e0SEric Dumazet (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && 21521da177e4SLinus Torvalds tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { 21531da177e4SLinus Torvalds if (!pskb_trim(skb, 0)) { 2154e870a8efSIlpo Järvinen /* Reuse, even though it does some unnecessary work */ 2155e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1, 21564de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags); 21571da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 21581da177e4SLinus Torvalds } 21591da177e4SLinus Torvalds } 21601da177e4SLinus Torvalds 21611da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 21621da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 21631da177e4SLinus Torvalds */ 21641da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 21651da177e4SLinus Torvalds 2166117632e6SEric Dumazet /* make sure skb->data is aligned on arches that require it */ 2167117632e6SEric Dumazet if (unlikely(NET_IP_ALIGN && ((unsigned long)skb->data & 3))) { 2168117632e6SEric Dumazet struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, 2169117632e6SEric Dumazet GFP_ATOMIC); 2170117632e6SEric Dumazet err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : 2171117632e6SEric Dumazet -ENOBUFS; 2172117632e6SEric Dumazet } else { 2173dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 2174117632e6SEric Dumazet } 21751da177e4SLinus Torvalds 21761da177e4SLinus Torvalds if (err == 0) { 21771da177e4SLinus Torvalds /* Update global TCP statistics. */ 217881cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 21791da177e4SLinus Torvalds 21801da177e4SLinus Torvalds tp->total_retrans++; 21811da177e4SLinus Torvalds 21821da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 21831da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 21841da177e4SLinus Torvalds if (net_ratelimit()) 21851da177e4SLinus Torvalds printk(KERN_DEBUG "retrans_out leaked.\n"); 21861da177e4SLinus Torvalds } 21871da177e4SLinus Torvalds #endif 2188b08d6cb2SIlpo Järvinen if (!tp->retrans_out) 2189b08d6cb2SIlpo Järvinen tp->lost_retrans_low = tp->snd_nxt; 21901da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 21911da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 21921da177e4SLinus Torvalds 21931da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 21941da177e4SLinus Torvalds if (!tp->retrans_stamp) 21951da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(skb)->when; 21961da177e4SLinus Torvalds 2197c24f691bSYuchung Cheng tp->undo_retrans += tcp_skb_pcount(skb); 21981da177e4SLinus Torvalds 21991da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 22001da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 22011da177e4SLinus Torvalds */ 22021da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 22031da177e4SLinus Torvalds } 22041da177e4SLinus Torvalds return err; 22051da177e4SLinus Torvalds } 22061da177e4SLinus Torvalds 220767edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 220867edfef7SAndi Kleen * window/congestion state. 220967edfef7SAndi Kleen */ 2210b5afe7bcSIlpo Järvinen static int tcp_can_forward_retransmit(struct sock *sk) 2211b5afe7bcSIlpo Järvinen { 2212b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2213cf533ea5SEric Dumazet const struct tcp_sock *tp = tcp_sk(sk); 2214b5afe7bcSIlpo Järvinen 2215b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2216b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2217b5afe7bcSIlpo Järvinen return 0; 2218b5afe7bcSIlpo Järvinen 2219b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2220b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2221b5afe7bcSIlpo Järvinen return 0; 2222b5afe7bcSIlpo Järvinen 2223b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2224b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2225b5afe7bcSIlpo Järvinen * 2226b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2227b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2228b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2229b5afe7bcSIlpo Järvinen */ 2230b5afe7bcSIlpo Järvinen 2231b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2232b5afe7bcSIlpo Järvinen return 0; 2233b5afe7bcSIlpo Järvinen 2234b5afe7bcSIlpo Järvinen return 1; 2235b5afe7bcSIlpo Järvinen } 2236b5afe7bcSIlpo Järvinen 22371da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 22381da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 22391da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 22401da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 22411da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 22421da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 22431da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 22441da177e4SLinus Torvalds */ 22451da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 22461da177e4SLinus Torvalds { 22476687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 22481da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 22491da177e4SLinus Torvalds struct sk_buff *skb; 22500e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2251618d9f25SIlpo Järvinen u32 last_lost; 225261eb55f4SIlpo Järvinen int mib_idx; 22530e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 22546a438bbeSStephen Hemminger 225545e77d31SIlpo Järvinen if (!tp->packets_out) 225645e77d31SIlpo Järvinen return; 225745e77d31SIlpo Järvinen 225808ebd172SIlpo Järvinen if (!tp->lost_out) 225908ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 226008ebd172SIlpo Järvinen 2261618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 22626a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2263618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2264618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2265618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2266618d9f25SIlpo Järvinen } else { 2267fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2268618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2269618d9f25SIlpo Järvinen } 22701da177e4SLinus Torvalds 2271fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 22721da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 22731da177e4SLinus Torvalds 2274fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2275fe067e8aSDavid S. Miller break; 22766a438bbeSStephen Hemminger /* we could do better than to assign each time */ 22770e1c54c2SIlpo Järvinen if (hole == NULL) 22786a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 22796a438bbeSStephen Hemminger 22801da177e4SLinus Torvalds /* Assume this retransmit will generate 22811da177e4SLinus Torvalds * only one packet for congestion window 22821da177e4SLinus Torvalds * calculation purposes. This works because 22831da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 22841da177e4SLinus Torvalds * packet to be MSS sized and all the 22851da177e4SLinus Torvalds * packet counting works out. 22861da177e4SLinus Torvalds */ 22871da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 22881da177e4SLinus Torvalds return; 22890e1c54c2SIlpo Järvinen 22900e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 22910e1c54c2SIlpo Järvinen begin_fwd: 22920e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2293006f582cSIlpo Järvinen break; 22940e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 22950e1c54c2SIlpo Järvinen 22960e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2297618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 22980e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 22990e1c54c2SIlpo Järvinen break; 23000e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 23010e1c54c2SIlpo Järvinen if (hole != NULL) { 23020e1c54c2SIlpo Järvinen skb = hole; 23030e1c54c2SIlpo Järvinen hole = NULL; 23040e1c54c2SIlpo Järvinen } 23050e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 23060e1c54c2SIlpo Järvinen goto begin_fwd; 23070e1c54c2SIlpo Järvinen 23080e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 2309ac11ba75SIlpo Järvinen if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 23100e1c54c2SIlpo Järvinen hole = skb; 231161eb55f4SIlpo Järvinen continue; 23121da177e4SLinus Torvalds 23130e1c54c2SIlpo Järvinen } else { 2314618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 23150e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 23160e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 23170e1c54c2SIlpo Järvinen else 23180e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 23190e1c54c2SIlpo Järvinen } 23200e1c54c2SIlpo Järvinen 23210e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 232261eb55f4SIlpo Järvinen continue; 232340b215e5SPavel Emelyanov 232409e9b813SEric Dumazet if (tcp_retransmit_skb(sk, skb)) { 232509e9b813SEric Dumazet NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); 23261da177e4SLinus Torvalds return; 232709e9b813SEric Dumazet } 2328de0744afSPavel Emelyanov NET_INC_STATS_BH(sock_net(sk), mib_idx); 23291da177e4SLinus Torvalds 2330a262f0cdSNandita Dukkipati if (inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery) 2331a262f0cdSNandita Dukkipati tp->prr_out += tcp_skb_pcount(skb); 2332a262f0cdSNandita Dukkipati 2333fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2334463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 23353f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 23363f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 23371da177e4SLinus Torvalds } 23381da177e4SLinus Torvalds } 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 23411da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 23421da177e4SLinus Torvalds */ 23431da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 23441da177e4SLinus Torvalds { 23451da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2346fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_write_queue_tail(sk); 23471da177e4SLinus Torvalds int mss_now; 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 23501da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 23511da177e4SLinus Torvalds * and IP options. 23521da177e4SLinus Torvalds */ 23530c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 23541da177e4SLinus Torvalds 2355fe067e8aSDavid S. Miller if (tcp_send_head(sk) != NULL) { 23564de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN; 23571da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 23581da177e4SLinus Torvalds tp->write_seq++; 23591da177e4SLinus Torvalds } else { 23601da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 23611da177e4SLinus Torvalds for (;;) { 2362aa133076SWu Fengguang skb = alloc_skb_fclone(MAX_TCP_HEADER, 2363aa133076SWu Fengguang sk->sk_allocation); 23641da177e4SLinus Torvalds if (skb) 23651da177e4SLinus Torvalds break; 23661da177e4SLinus Torvalds yield(); 23671da177e4SLinus Torvalds } 23681da177e4SLinus Torvalds 23691da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 23701da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 23711da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 2372e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 2373a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 23741da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 23751da177e4SLinus Torvalds } 23769e412ba7SIlpo Järvinen __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); 23771da177e4SLinus Torvalds } 23781da177e4SLinus Torvalds 23791da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 23801da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 23811da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 238265bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 23831da177e4SLinus Torvalds */ 2384dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 23851da177e4SLinus Torvalds { 23861da177e4SLinus Torvalds struct sk_buff *skb; 23871da177e4SLinus Torvalds 23881da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 23891da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 23901da177e4SLinus Torvalds if (!skb) { 23914e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 23921da177e4SLinus Torvalds return; 23931da177e4SLinus Torvalds } 23941da177e4SLinus Torvalds 23951da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 23961da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 2397e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 2398a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 23991da177e4SLinus Torvalds /* Send it off. */ 24001da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2401dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 24024e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 240326af65cbSSridhar Samudrala 240481cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 24051da177e4SLinus Torvalds } 24061da177e4SLinus Torvalds 240767edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 240867edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 24091da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 24101da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 24111da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 24121da177e4SLinus Torvalds */ 24131da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 24141da177e4SLinus Torvalds { 24151da177e4SLinus Torvalds struct sk_buff *skb; 24161da177e4SLinus Torvalds 2417fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 24184de075e0SEric Dumazet if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { 24191da177e4SLinus Torvalds printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); 24201da177e4SLinus Torvalds return -EFAULT; 24211da177e4SLinus Torvalds } 24224de075e0SEric Dumazet if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { 24231da177e4SLinus Torvalds if (skb_cloned(skb)) { 24241da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 24251da177e4SLinus Torvalds if (nskb == NULL) 24261da177e4SLinus Torvalds return -ENOMEM; 2427fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 24281da177e4SLinus Torvalds skb_header_release(nskb); 2429fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 24303ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 24313ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 24323ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 24331da177e4SLinus Torvalds skb = nskb; 24341da177e4SLinus Torvalds } 24351da177e4SLinus Torvalds 24364de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; 24371da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 24381da177e4SLinus Torvalds } 24391da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2440dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 24411da177e4SLinus Torvalds } 24421da177e4SLinus Torvalds 244367edfef7SAndi Kleen /* Prepare a SYN-ACK. */ 24441da177e4SLinus Torvalds struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 2445e6b4d113SWilliam Allen Simpson struct request_sock *req, 2446e6b4d113SWilliam Allen Simpson struct request_values *rvp) 24471da177e4SLinus Torvalds { 2448bd0388aeSWilliam Allen Simpson struct tcp_out_options opts; 24494957faadSWilliam Allen Simpson struct tcp_extend_values *xvp = tcp_xv(rvp); 24502e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 24511da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 245228b2774aSEric Dumazet const struct tcp_cookie_values *cvp = tp->cookie_values; 24531da177e4SLinus Torvalds struct tcphdr *th; 24541da177e4SLinus Torvalds struct sk_buff *skb; 2455cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 2456bd0388aeSWilliam Allen Simpson int tcp_header_size; 2457f5fff5dcSTom Quetchenbach int mss; 245828b2774aSEric Dumazet int s_data_desired = 0; 24591da177e4SLinus Torvalds 246028b2774aSEric Dumazet if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired) 246128b2774aSEric Dumazet s_data_desired = cvp->s_data_desired; 246228b2774aSEric Dumazet skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1, GFP_ATOMIC); 24631da177e4SLinus Torvalds if (skb == NULL) 24641da177e4SLinus Torvalds return NULL; 24651da177e4SLinus Torvalds 24661da177e4SLinus Torvalds /* Reserve space for headers. */ 24671da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 24681da177e4SLinus Torvalds 2469adf30907SEric Dumazet skb_dst_set(skb, dst_clone(dst)); 24701da177e4SLinus Torvalds 24710dbaee3bSDavid S. Miller mss = dst_metric_advmss(dst); 2472f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) 2473f5fff5dcSTom Quetchenbach mss = tp->rx_opt.user_mss; 2474f5fff5dcSTom Quetchenbach 247533ad798cSAdam Langley if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ 247633ad798cSAdam Langley __u8 rcv_wscale; 247733ad798cSAdam Langley /* Set this up on the first call only */ 247833ad798cSAdam Langley req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); 2479e88c64f0SHagen Paul Pfeifer 2480e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 2481e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 2482e88c64f0SHagen Paul Pfeifer (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0)) 2483e88c64f0SHagen Paul Pfeifer req->window_clamp = tcp_full_space(sk); 2484e88c64f0SHagen Paul Pfeifer 248533ad798cSAdam Langley /* tcp_full_space because it is guaranteed to be the first packet */ 248633ad798cSAdam Langley tcp_select_initial_window(tcp_full_space(sk), 2487f5fff5dcSTom Quetchenbach mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), 248833ad798cSAdam Langley &req->rcv_wnd, 248933ad798cSAdam Langley &req->window_clamp, 249033ad798cSAdam Langley ireq->wscale_ok, 249131d12926Slaurent chavey &rcv_wscale, 249231d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 249333ad798cSAdam Langley ireq->rcv_wscale = rcv_wscale; 249433ad798cSAdam Langley } 2495cfb6eeb4SYOSHIFUJI Hideaki 249633ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 24978b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 24988b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 24998b5f12d0SFlorian Westphal TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); 25008b5f12d0SFlorian Westphal else 25018b5f12d0SFlorian Westphal #endif 250233ad798cSAdam Langley TCP_SKB_CB(skb)->when = tcp_time_stamp; 2503f5fff5dcSTom Quetchenbach tcp_header_size = tcp_synack_options(sk, req, mss, 25044957faadSWilliam Allen Simpson skb, &opts, &md5, xvp) 25054957faadSWilliam Allen Simpson + sizeof(*th); 250633ad798cSAdam Langley 2507aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 2508aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 25091da177e4SLinus Torvalds 2510aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 25111da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 25121da177e4SLinus Torvalds th->syn = 1; 25131da177e4SLinus Torvalds th->ack = 1; 25141da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 2515a3116ac5SKOVACS Krisztian th->source = ireq->loc_port; 25162e6599cbSArnaldo Carvalho de Melo th->dest = ireq->rmt_port; 2517e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 2518e870a8efSIlpo Järvinen * not even correctly set) 2519e870a8efSIlpo Järvinen */ 2520e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 2521a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 25224957faadSWilliam Allen Simpson 25234957faadSWilliam Allen Simpson if (OPTION_COOKIE_EXTENSION & opts.options) { 252428b2774aSEric Dumazet if (s_data_desired) { 252528b2774aSEric Dumazet u8 *buf = skb_put(skb, s_data_desired); 25264957faadSWilliam Allen Simpson 25274957faadSWilliam Allen Simpson /* copy data directly from the listening socket. */ 252828b2774aSEric Dumazet memcpy(buf, cvp->s_data_payload, s_data_desired); 252928b2774aSEric Dumazet TCP_SKB_CB(skb)->end_seq += s_data_desired; 25304957faadSWilliam Allen Simpson } 25314957faadSWilliam Allen Simpson 25324957faadSWilliam Allen Simpson if (opts.hash_size > 0) { 25334957faadSWilliam Allen Simpson __u32 workspace[SHA_WORKSPACE_WORDS]; 25344957faadSWilliam Allen Simpson u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS]; 25354957faadSWilliam Allen Simpson u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1]; 25364957faadSWilliam Allen Simpson 25374957faadSWilliam Allen Simpson /* Secret recipe depends on the Timestamp, (future) 25384957faadSWilliam Allen Simpson * Sequence and Acknowledgment Numbers, Initiator 25394957faadSWilliam Allen Simpson * Cookie, and others handled by IP variant caller. 25404957faadSWilliam Allen Simpson */ 25414957faadSWilliam Allen Simpson *tail-- ^= opts.tsval; 25424957faadSWilliam Allen Simpson *tail-- ^= tcp_rsk(req)->rcv_isn + 1; 25434957faadSWilliam Allen Simpson *tail-- ^= TCP_SKB_CB(skb)->seq + 1; 25444957faadSWilliam Allen Simpson 25454957faadSWilliam Allen Simpson /* recommended */ 25460eae88f3SEric Dumazet *tail-- ^= (((__force u32)th->dest << 16) | (__force u32)th->source); 2547f9a2e69eSDavid S. Miller *tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */ 25484957faadSWilliam Allen Simpson 25494957faadSWilliam Allen Simpson sha_transform((__u32 *)&xvp->cookie_bakery[0], 25504957faadSWilliam Allen Simpson (char *)mess, 25514957faadSWilliam Allen Simpson &workspace[0]); 25524957faadSWilliam Allen Simpson opts.hash_location = 25534957faadSWilliam Allen Simpson (__u8 *)&xvp->cookie_bakery[0]; 25544957faadSWilliam Allen Simpson } 25554957faadSWilliam Allen Simpson } 25564957faadSWilliam Allen Simpson 25571da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 25582e6599cbSArnaldo Carvalho de Melo th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 2561600ff0c2SIlpo Järvinen th->window = htons(min(req->rcv_wnd, 65535U)); 2562bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 25631da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 2564aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb)); 2565cfb6eeb4SYOSHIFUJI Hideaki 2566cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2567cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 2568cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 2569bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 257049a72dfbSAdam Langley md5, NULL, req, skb); 2571cfb6eeb4SYOSHIFUJI Hideaki } 2572cfb6eeb4SYOSHIFUJI Hideaki #endif 2573cfb6eeb4SYOSHIFUJI Hideaki 25741da177e4SLinus Torvalds return skb; 25751da177e4SLinus Torvalds } 25764bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_make_synack); 25771da177e4SLinus Torvalds 257867edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 2579370816aeSPavel Emelyanov void tcp_connect_init(struct sock *sk) 25801da177e4SLinus Torvalds { 2581cf533ea5SEric Dumazet const struct dst_entry *dst = __sk_dst_get(sk); 25821da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 25831da177e4SLinus Torvalds __u8 rcv_wscale; 25841da177e4SLinus Torvalds 25851da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 25861da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 25871da177e4SLinus Torvalds */ 25881da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 2589bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 25901da177e4SLinus Torvalds 2591cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2592cfb6eeb4SYOSHIFUJI Hideaki if (tp->af_specific->md5_lookup(sk, sk) != NULL) 2593cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 2594cfb6eeb4SYOSHIFUJI Hideaki #endif 2595cfb6eeb4SYOSHIFUJI Hideaki 25961da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 25971da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 25981da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 25991da177e4SLinus Torvalds tp->max_window = 0; 26005d424d5aSJohn Heffner tcp_mtup_init(sk); 26011da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 26021da177e4SLinus Torvalds 26031da177e4SLinus Torvalds if (!tp->window_clamp) 26041da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 26050dbaee3bSDavid S. Miller tp->advmss = dst_metric_advmss(dst); 2606f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 2607f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 2608f5fff5dcSTom Quetchenbach 26091da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 26101da177e4SLinus Torvalds 2611e88c64f0SHagen Paul Pfeifer /* limit the window selection if the user enforce a smaller rx buffer */ 2612e88c64f0SHagen Paul Pfeifer if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && 2613e88c64f0SHagen Paul Pfeifer (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) 2614e88c64f0SHagen Paul Pfeifer tp->window_clamp = tcp_full_space(sk); 2615e88c64f0SHagen Paul Pfeifer 26161da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 26171da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 26181da177e4SLinus Torvalds &tp->rcv_wnd, 26191da177e4SLinus Torvalds &tp->window_clamp, 2620bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 262131d12926Slaurent chavey &rcv_wscale, 262231d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 26231da177e4SLinus Torvalds 26241da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 26251da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 26261da177e4SLinus Torvalds 26271da177e4SLinus Torvalds sk->sk_err = 0; 26281da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 26291da177e4SLinus Torvalds tp->snd_wnd = 0; 2630ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 26311da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 26321da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 263333f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 2634370816aeSPavel Emelyanov tp->snd_nxt = tp->write_seq; 2635ee995283SPavel Emelyanov 2636ee995283SPavel Emelyanov if (likely(!tp->repair)) 26371da177e4SLinus Torvalds tp->rcv_nxt = 0; 2638ee995283SPavel Emelyanov tp->rcv_wup = tp->rcv_nxt; 2639ee995283SPavel Emelyanov tp->copied_seq = tp->rcv_nxt; 26401da177e4SLinus Torvalds 2641463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 2642463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 26431da177e4SLinus Torvalds tcp_clear_retrans(tp); 26441da177e4SLinus Torvalds } 26451da177e4SLinus Torvalds 264667edfef7SAndi Kleen /* Build a SYN and send it off. */ 26471da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 26481da177e4SLinus Torvalds { 26491da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 26501da177e4SLinus Torvalds struct sk_buff *buff; 2651ee586811SEric Paris int err; 26521da177e4SLinus Torvalds 26531da177e4SLinus Torvalds tcp_connect_init(sk); 26541da177e4SLinus Torvalds 2655d179cd12SDavid S. Miller buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); 26561da177e4SLinus Torvalds if (unlikely(buff == NULL)) 26571da177e4SLinus Torvalds return -ENOBUFS; 26581da177e4SLinus Torvalds 26591da177e4SLinus Torvalds /* Reserve space for headers. */ 26601da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 26611da177e4SLinus Torvalds 2662a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 2663e870a8efSIlpo Järvinen TCP_ECN_send_syn(sk, buff); 26641da177e4SLinus Torvalds 26651da177e4SLinus Torvalds /* Send it off. */ 26661da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 26671da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(buff)->when; 26681da177e4SLinus Torvalds skb_header_release(buff); 2669fe067e8aSDavid S. Miller __tcp_add_write_queue_tail(sk, buff); 26703ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 26713ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 26721da177e4SLinus Torvalds tp->packets_out += tcp_skb_pcount(buff); 2673ee586811SEric Paris err = tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 2674ee586811SEric Paris if (err == -ECONNREFUSED) 2675ee586811SEric Paris return err; 2676bd37a088SWei Yongjun 2677bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 2678bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 2679bd37a088SWei Yongjun */ 2680bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 2681bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 268281cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 26831da177e4SLinus Torvalds 26841da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 26853f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 26863f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 26871da177e4SLinus Torvalds return 0; 26881da177e4SLinus Torvalds } 26894bc2f18bSEric Dumazet EXPORT_SYMBOL(tcp_connect); 26901da177e4SLinus Torvalds 26911da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 26921da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 26931da177e4SLinus Torvalds * for details. 26941da177e4SLinus Torvalds */ 26951da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 26961da177e4SLinus Torvalds { 2697463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 2698463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 26991da177e4SLinus Torvalds unsigned long timeout; 27001da177e4SLinus Torvalds 27011da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 2702463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 27031da177e4SLinus Torvalds int max_ato = HZ / 2; 27041da177e4SLinus Torvalds 2705056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 2706056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 27071da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 27081da177e4SLinus Torvalds 27091da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 27101da177e4SLinus Torvalds 27111da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 2712463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 27131da177e4SLinus Torvalds * directly. 27141da177e4SLinus Torvalds */ 27151da177e4SLinus Torvalds if (tp->srtt) { 27161da177e4SLinus Torvalds int rtt = max(tp->srtt >> 3, TCP_DELACK_MIN); 27171da177e4SLinus Torvalds 27181da177e4SLinus Torvalds if (rtt < max_ato) 27191da177e4SLinus Torvalds max_ato = rtt; 27201da177e4SLinus Torvalds } 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds ato = min(ato, max_ato); 27231da177e4SLinus Torvalds } 27241da177e4SLinus Torvalds 27251da177e4SLinus Torvalds /* Stay within the limit we were given */ 27261da177e4SLinus Torvalds timeout = jiffies + ato; 27271da177e4SLinus Torvalds 27281da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 2729463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 27301da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 27311da177e4SLinus Torvalds * send ACK now. 27321da177e4SLinus Torvalds */ 2733463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 2734463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 27351da177e4SLinus Torvalds tcp_send_ack(sk); 27361da177e4SLinus Torvalds return; 27371da177e4SLinus Torvalds } 27381da177e4SLinus Torvalds 2739463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 2740463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 27411da177e4SLinus Torvalds } 2742463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 2743463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 2744463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 27451da177e4SLinus Torvalds } 27461da177e4SLinus Torvalds 27471da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 27481da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 27491da177e4SLinus Torvalds { 27501da177e4SLinus Torvalds struct sk_buff *buff; 27511da177e4SLinus Torvalds 2752058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 2753058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 2754058dc334SIlpo Järvinen return; 2755058dc334SIlpo Järvinen 27561da177e4SLinus Torvalds /* We are not putting this on the write queue, so 27571da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 27581da177e4SLinus Torvalds * sock. 27591da177e4SLinus Torvalds */ 27601da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 27611da177e4SLinus Torvalds if (buff == NULL) { 2762463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 2763463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 27643f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 27653f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 27661da177e4SLinus Torvalds return; 27671da177e4SLinus Torvalds } 27681da177e4SLinus Torvalds 27691da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 27701da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 2771a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 27721da177e4SLinus Torvalds 27731da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 27741da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 2775dfb4b9dcSDavid S. Miller tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC); 27761da177e4SLinus Torvalds } 27771da177e4SLinus Torvalds 27781da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 27791da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 27801da177e4SLinus Torvalds * 27811da177e4SLinus Torvalds * Question: what should we make while urgent mode? 27821da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 27831da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 27841da177e4SLinus Torvalds * 27851da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 27861da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 27871da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 27881da177e4SLinus Torvalds */ 27891da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 27901da177e4SLinus Torvalds { 27911da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27921da177e4SLinus Torvalds struct sk_buff *skb; 27931da177e4SLinus Torvalds 27941da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 27951da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 27961da177e4SLinus Torvalds if (skb == NULL) 27971da177e4SLinus Torvalds return -1; 27981da177e4SLinus Torvalds 27991da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 28001da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 28011da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 28021da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 28031da177e4SLinus Torvalds * send it. 28041da177e4SLinus Torvalds */ 2805a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 28061da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2807dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 2810ee995283SPavel Emelyanov void tcp_send_window_probe(struct sock *sk) 2811ee995283SPavel Emelyanov { 2812ee995283SPavel Emelyanov if (sk->sk_state == TCP_ESTABLISHED) { 2813ee995283SPavel Emelyanov tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; 2814c0e88ff0SPavel Emelyanov tcp_sk(sk)->snd_nxt = tcp_sk(sk)->write_seq; 2815ee995283SPavel Emelyanov tcp_xmit_probe_skb(sk, 0); 2816ee995283SPavel Emelyanov } 2817ee995283SPavel Emelyanov } 2818ee995283SPavel Emelyanov 281967edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 28201da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 28211da177e4SLinus Torvalds { 28221da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 28231da177e4SLinus Torvalds struct sk_buff *skb; 28241da177e4SLinus Torvalds 2825058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 2826058dc334SIlpo Järvinen return -1; 2827058dc334SIlpo Järvinen 2828fe067e8aSDavid S. Miller if ((skb = tcp_send_head(sk)) != NULL && 282990840defSIlpo Järvinen before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 28301da177e4SLinus Torvalds int err; 28310c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 283290840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 28331da177e4SLinus Torvalds 28341da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 28351da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 28361da177e4SLinus Torvalds 28371da177e4SLinus Torvalds /* We are probing the opening of a window 28381da177e4SLinus Torvalds * but the window size is != 0 28391da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 28401da177e4SLinus Torvalds */ 28411da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 28421da177e4SLinus Torvalds skb->len > mss) { 28431da177e4SLinus Torvalds seg_size = min(seg_size, mss); 28444de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 2845846998aeSDavid S. Miller if (tcp_fragment(sk, skb, seg_size, mss)) 28461da177e4SLinus Torvalds return -1; 28471da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 2848846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 28491da177e4SLinus Torvalds 28504de075e0SEric Dumazet TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; 28511da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2852dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 285366f5fe62SIlpo Järvinen if (!err) 285466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 28551da177e4SLinus Torvalds return err; 28561da177e4SLinus Torvalds } else { 285733f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 28584828e7f4SIlpo Järvinen tcp_xmit_probe_skb(sk, 1); 28591da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 28601da177e4SLinus Torvalds } 28611da177e4SLinus Torvalds } 28621da177e4SLinus Torvalds 28631da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 28641da177e4SLinus Torvalds * a partial packet else a zero probe. 28651da177e4SLinus Torvalds */ 28661da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 28671da177e4SLinus Torvalds { 2868463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 28691da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 28701da177e4SLinus Torvalds int err; 28711da177e4SLinus Torvalds 28721da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 28731da177e4SLinus Torvalds 2874fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 28751da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 28766687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 2877463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 28781da177e4SLinus Torvalds return; 28791da177e4SLinus Torvalds } 28801da177e4SLinus Torvalds 28811da177e4SLinus Torvalds if (err <= 0) { 2882463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_backoff < sysctl_tcp_retries2) 2883463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 28846687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 2885463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 28863f421baaSArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), 28873f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 28881da177e4SLinus Torvalds } else { 28891da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 28906687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 28911da177e4SLinus Torvalds * Let local senders to fight for local resources. 28921da177e4SLinus Torvalds * 28931da177e4SLinus Torvalds * Use accumulated backoff yet. 28941da177e4SLinus Torvalds */ 28956687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 28966687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 2897463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 2898463c84b9SArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, 28993f421baaSArnaldo Carvalho de Melo TCP_RESOURCE_PROBE_INTERVAL), 29003f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 29011da177e4SLinus Torvalds } 29021da177e4SLinus Torvalds } 2903