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; 58ab32ea5dSBrian Haley int sysctl_tcp_base_mss __read_mostly = 512; 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. */ 6866f5fe62SIlpo Järvinen static void tcp_event_new_data_sent(struct sock *sk, 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 768512430eSIlpo Järvinen /* Don't override Nagle indefinately 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); 8166f5fe62SIlpo Järvinen if (!prior_packets) 8266f5fe62SIlpo Järvinen inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 8366f5fe62SIlpo Järvinen inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 841da177e4SLinus Torvalds } 851da177e4SLinus Torvalds 861da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 871da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 881da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 891da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 901da177e4SLinus Torvalds * invalid. OK, let's make this for now: 911da177e4SLinus Torvalds */ 929e412ba7SIlpo Järvinen static inline __u32 tcp_acceptable_seq(struct sock *sk) 931da177e4SLinus Torvalds { 949e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 959e412ba7SIlpo Järvinen 9690840defSIlpo Järvinen if (!before(tcp_wnd_end(tp), tp->snd_nxt)) 971da177e4SLinus Torvalds return tp->snd_nxt; 981da177e4SLinus Torvalds else 9990840defSIlpo Järvinen return tcp_wnd_end(tp); 1001da177e4SLinus Torvalds } 1011da177e4SLinus Torvalds 1021da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 1031da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * 1. It is independent of path mtu. 1061da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 1071da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 1081da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 1091da177e4SLinus Torvalds * large MSS. 1101da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 1111da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 1121da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 1131da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 1141da177e4SLinus Torvalds * probably even Jumbo". 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 1171da177e4SLinus Torvalds { 1181da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1191da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 1201da177e4SLinus Torvalds int mss = tp->advmss; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { 1231da177e4SLinus Torvalds mss = dst_metric(dst, RTAX_ADVMSS); 1241da177e4SLinus Torvalds tp->advmss = mss; 1251da177e4SLinus Torvalds } 1261da177e4SLinus Torvalds 1271da177e4SLinus Torvalds return (__u16)mss; 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1311da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 132463c84b9SArnaldo Carvalho de Melo static void tcp_cwnd_restart(struct sock *sk, struct dst_entry *dst) 1331da177e4SLinus Torvalds { 134463c84b9SArnaldo Carvalho de Melo struct tcp_sock *tp = tcp_sk(sk); 1351da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1361da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1371da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1381da177e4SLinus Torvalds 1396687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_CWND_RESTART); 1401da177e4SLinus Torvalds 1416687e988SArnaldo Carvalho de Melo tp->snd_ssthresh = tcp_current_ssthresh(sk); 1421da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1431da177e4SLinus Torvalds 144463c84b9SArnaldo Carvalho de Melo while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) 1451da177e4SLinus Torvalds cwnd >>= 1; 1461da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1471da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1481da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1491da177e4SLinus Torvalds } 1501da177e4SLinus Torvalds 15167edfef7SAndi Kleen /* Congestion state accounting after a packet has been sent. */ 15240efc6faSStephen Hemminger static void tcp_event_data_sent(struct tcp_sock *tp, 1531da177e4SLinus Torvalds struct sk_buff *skb, struct sock *sk) 1541da177e4SLinus Torvalds { 155463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 156463c84b9SArnaldo Carvalho de Melo const u32 now = tcp_time_stamp; 1571da177e4SLinus Torvalds 15835089bb2SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 15935089bb2SDavid S. Miller (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) 160463c84b9SArnaldo Carvalho de Melo tcp_cwnd_restart(sk, __sk_dst_get(sk)); 1611da177e4SLinus Torvalds 1621da177e4SLinus Torvalds tp->lsndtime = now; 1631da177e4SLinus Torvalds 1641da177e4SLinus Torvalds /* If it is a reply for ato after last received 1651da177e4SLinus Torvalds * packet, enter pingpong mode. 1661da177e4SLinus Torvalds */ 167463c84b9SArnaldo Carvalho de Melo if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) 168463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pingpong = 1; 1691da177e4SLinus Torvalds } 1701da177e4SLinus Torvalds 17167edfef7SAndi Kleen /* Account for an ACK we sent. */ 17240efc6faSStephen Hemminger static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) 1731da177e4SLinus Torvalds { 174463c84b9SArnaldo Carvalho de Melo tcp_dec_quickack_mode(sk, pkts); 175463c84b9SArnaldo Carvalho de Melo inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); 1761da177e4SLinus Torvalds } 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 1791da177e4SLinus Torvalds * Based on the assumption that the given amount of space 1801da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 1811da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 1821da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 1831da177e4SLinus Torvalds * This MUST be enforced by all callers. 1841da177e4SLinus Torvalds */ 1851da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 1861da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 18731d12926Slaurent chavey int wscale_ok, __u8 *rcv_wscale, 18831d12926Slaurent chavey __u32 init_rcv_wnd) 1891da177e4SLinus Torvalds { 1901da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 1911da177e4SLinus Torvalds 1921da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 1931da177e4SLinus Torvalds if (*window_clamp == 0) 1941da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 1951da177e4SLinus Torvalds space = min(*window_clamp, space); 1961da177e4SLinus Torvalds 1971da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 1981da177e4SLinus Torvalds if (space > mss) 1991da177e4SLinus Torvalds space = (space / mss) * mss; 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 20215d99e02SRick Jones * will break some buggy TCP stacks. If the admin tells us 20315d99e02SRick Jones * it is likely we could be speaking with such a buggy stack 20415d99e02SRick Jones * we will truncate our initial window offering to 32K-1 20515d99e02SRick Jones * unless the remote has sent us a window scaling option, 20615d99e02SRick Jones * which we interpret as a sign the remote TCP is not 20715d99e02SRick Jones * misinterpreting the window field as a signed quantity. 2081da177e4SLinus Torvalds */ 20915d99e02SRick Jones if (sysctl_tcp_workaround_signed_windows) 2101da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 21115d99e02SRick Jones else 21215d99e02SRick Jones (*rcv_wnd) = space; 21315d99e02SRick Jones 2141da177e4SLinus Torvalds (*rcv_wscale) = 0; 2151da177e4SLinus Torvalds if (wscale_ok) { 2161da177e4SLinus Torvalds /* Set window scaling on max possible window 2171da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 2181da177e4SLinus Torvalds */ 2191da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 220316c1592SStephen Hemminger space = min_t(u32, space, *window_clamp); 2211da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 2221da177e4SLinus Torvalds space >>= 1; 2231da177e4SLinus Torvalds (*rcv_wscale)++; 2241da177e4SLinus Torvalds } 2251da177e4SLinus Torvalds } 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds /* Set initial window to value enough for senders, 2286b251858SDavid S. Miller * following RFC2414. Senders, not following this RFC, 2291da177e4SLinus Torvalds * will be satisfied with 2. 2301da177e4SLinus Torvalds */ 2311da177e4SLinus Torvalds if (mss > (1 << *rcv_wscale)) { 23201ff367eSDavid S. Miller int init_cwnd = 4; 23301ff367eSDavid S. Miller if (mss > 1460 * 3) 2341da177e4SLinus Torvalds init_cwnd = 2; 23501ff367eSDavid S. Miller else if (mss > 1460) 23601ff367eSDavid S. Miller init_cwnd = 3; 23731d12926Slaurent chavey /* when initializing use the value from init_rcv_wnd 23831d12926Slaurent chavey * rather than the default from above 23931d12926Slaurent chavey */ 24031d12926Slaurent chavey if (init_rcv_wnd && 24131d12926Slaurent chavey (*rcv_wnd > init_rcv_wnd * mss)) 24231d12926Slaurent chavey *rcv_wnd = init_rcv_wnd * mss; 24331d12926Slaurent chavey else if (*rcv_wnd > init_cwnd * mss) 2441da177e4SLinus Torvalds *rcv_wnd = init_cwnd * mss; 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2481da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2491da177e4SLinus Torvalds } 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2521da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2531da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2541da177e4SLinus Torvalds * frame. 2551da177e4SLinus Torvalds */ 25640efc6faSStephen Hemminger static u16 tcp_select_window(struct sock *sk) 2571da177e4SLinus Torvalds { 2581da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2591da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2601da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2611da177e4SLinus Torvalds 2621da177e4SLinus Torvalds /* Never shrink the offered window */ 2631da177e4SLinus Torvalds if (new_win < cur_win) { 2641da177e4SLinus Torvalds /* Danger Will Robinson! 2651da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2661da177e4SLinus Torvalds * we will not be able to advertise a zero 2671da177e4SLinus Torvalds * window in time. --DaveM 2681da177e4SLinus Torvalds * 2691da177e4SLinus Torvalds * Relax Will Robinson. 2701da177e4SLinus Torvalds */ 271607bfbf2SPatrick McHardy new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2741da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2771da177e4SLinus Torvalds * scaled window. 2781da177e4SLinus Torvalds */ 27915d99e02SRick Jones if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) 2801da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2811da177e4SLinus Torvalds else 2821da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2831da177e4SLinus Torvalds 2841da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2851da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2861da177e4SLinus Torvalds 2871da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 2881da177e4SLinus Torvalds if (new_win == 0) 2891da177e4SLinus Torvalds tp->pred_flags = 0; 2901da177e4SLinus Torvalds 2911da177e4SLinus Torvalds return new_win; 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds 29467edfef7SAndi Kleen /* Packet ECN state for a SYN-ACK */ 295056834d9SIlpo Järvinen static inline void TCP_ECN_send_synack(struct tcp_sock *tp, struct sk_buff *skb) 296bdf1ee5dSIlpo Järvinen { 297a3433f35SChangli Gao TCP_SKB_CB(skb)->flags &= ~TCPHDR_CWR; 298bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 299a3433f35SChangli Gao TCP_SKB_CB(skb)->flags &= ~TCPHDR_ECE; 300bdf1ee5dSIlpo Järvinen } 301bdf1ee5dSIlpo Järvinen 30267edfef7SAndi Kleen /* Packet ECN state for a SYN. */ 303bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) 304bdf1ee5dSIlpo Järvinen { 305bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 306bdf1ee5dSIlpo Järvinen 307bdf1ee5dSIlpo Järvinen tp->ecn_flags = 0; 308255cac91SIlpo Järvinen if (sysctl_tcp_ecn == 1) { 309a3433f35SChangli Gao TCP_SKB_CB(skb)->flags |= TCPHDR_ECE | TCPHDR_CWR; 310bdf1ee5dSIlpo Järvinen tp->ecn_flags = TCP_ECN_OK; 311bdf1ee5dSIlpo Järvinen } 312bdf1ee5dSIlpo Järvinen } 313bdf1ee5dSIlpo Järvinen 314bdf1ee5dSIlpo Järvinen static __inline__ void 315bdf1ee5dSIlpo Järvinen TCP_ECN_make_synack(struct request_sock *req, struct tcphdr *th) 316bdf1ee5dSIlpo Järvinen { 317bdf1ee5dSIlpo Järvinen if (inet_rsk(req)->ecn_ok) 318bdf1ee5dSIlpo Järvinen th->ece = 1; 319bdf1ee5dSIlpo Järvinen } 320bdf1ee5dSIlpo Järvinen 32167edfef7SAndi Kleen /* Set up ECN state for a packet on a ESTABLISHED socket that is about to 32267edfef7SAndi Kleen * be sent. 32367edfef7SAndi Kleen */ 324bdf1ee5dSIlpo Järvinen static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, 325bdf1ee5dSIlpo Järvinen int tcp_header_len) 326bdf1ee5dSIlpo Järvinen { 327bdf1ee5dSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 328bdf1ee5dSIlpo Järvinen 329bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_OK) { 330bdf1ee5dSIlpo Järvinen /* Not-retransmitted data segment: set ECT and inject CWR. */ 331bdf1ee5dSIlpo Järvinen if (skb->len != tcp_header_len && 332bdf1ee5dSIlpo Järvinen !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { 333bdf1ee5dSIlpo Järvinen INET_ECN_xmit(sk); 334bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { 335bdf1ee5dSIlpo Järvinen tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; 336bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->cwr = 1; 337bdf1ee5dSIlpo Järvinen skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; 338bdf1ee5dSIlpo Järvinen } 339bdf1ee5dSIlpo Järvinen } else { 340bdf1ee5dSIlpo Järvinen /* ACK or retransmitted segment: clear ECT|CE */ 341bdf1ee5dSIlpo Järvinen INET_ECN_dontxmit(sk); 342bdf1ee5dSIlpo Järvinen } 343bdf1ee5dSIlpo Järvinen if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) 344bdf1ee5dSIlpo Järvinen tcp_hdr(skb)->ece = 1; 345bdf1ee5dSIlpo Järvinen } 346bdf1ee5dSIlpo Järvinen } 347bdf1ee5dSIlpo Järvinen 348e870a8efSIlpo Järvinen /* Constructs common control bits of non-data skb. If SYN/FIN is present, 349e870a8efSIlpo Järvinen * auto increment end seqno. 350e870a8efSIlpo Järvinen */ 351e870a8efSIlpo Järvinen static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) 352e870a8efSIlpo Järvinen { 3532e8e18efSDavid S. Miller skb->ip_summed = CHECKSUM_PARTIAL; 354e870a8efSIlpo Järvinen skb->csum = 0; 355e870a8efSIlpo Järvinen 356e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->flags = flags; 357e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->sacked = 0; 358e870a8efSIlpo Järvinen 359e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_segs = 1; 360e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_size = 0; 361e870a8efSIlpo Järvinen skb_shinfo(skb)->gso_type = 0; 362e870a8efSIlpo Järvinen 363e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->seq = seq; 364a3433f35SChangli Gao if (flags & (TCPHDR_SYN | TCPHDR_FIN)) 365e870a8efSIlpo Järvinen seq++; 366e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->end_seq = seq; 367e870a8efSIlpo Järvinen } 368e870a8efSIlpo Järvinen 36933f5f57eSIlpo Järvinen static inline int tcp_urg_mode(const struct tcp_sock *tp) 37033f5f57eSIlpo Järvinen { 37133f5f57eSIlpo Järvinen return tp->snd_una != tp->snd_up; 37233f5f57eSIlpo Järvinen } 37333f5f57eSIlpo Järvinen 37433ad798cSAdam Langley #define OPTION_SACK_ADVERTISE (1 << 0) 37533ad798cSAdam Langley #define OPTION_TS (1 << 1) 37633ad798cSAdam Langley #define OPTION_MD5 (1 << 2) 37789e95a61SOri Finkelman #define OPTION_WSCALE (1 << 3) 378bd0388aeSWilliam Allen Simpson #define OPTION_COOKIE_EXTENSION (1 << 4) 37933ad798cSAdam Langley 38033ad798cSAdam Langley struct tcp_out_options { 38133ad798cSAdam Langley u8 options; /* bit field of OPTION_* */ 38233ad798cSAdam Langley u8 ws; /* window scale, 0 to disable */ 38333ad798cSAdam Langley u8 num_sack_blocks; /* number of SACK blocks to include */ 384bd0388aeSWilliam Allen Simpson u8 hash_size; /* bytes in hash_location */ 38533ad798cSAdam Langley u16 mss; /* 0 to disable */ 38633ad798cSAdam Langley __u32 tsval, tsecr; /* need to include OPTION_TS */ 387bd0388aeSWilliam Allen Simpson __u8 *hash_location; /* temporary pointer, overloaded */ 38833ad798cSAdam Langley }; 38933ad798cSAdam Langley 390bd0388aeSWilliam Allen Simpson /* The sysctl int routines are generic, so check consistency here. 391bd0388aeSWilliam Allen Simpson */ 392bd0388aeSWilliam Allen Simpson static u8 tcp_cookie_size_check(u8 desired) 393bd0388aeSWilliam Allen Simpson { 394bd0388aeSWilliam Allen Simpson if (desired > 0) { 395bd0388aeSWilliam Allen Simpson /* previously specified */ 396bd0388aeSWilliam Allen Simpson return desired; 397bd0388aeSWilliam Allen Simpson } 398bd0388aeSWilliam Allen Simpson if (sysctl_tcp_cookie_size <= 0) { 399bd0388aeSWilliam Allen Simpson /* no default specified */ 400bd0388aeSWilliam Allen Simpson return 0; 401bd0388aeSWilliam Allen Simpson } 402bd0388aeSWilliam Allen Simpson if (sysctl_tcp_cookie_size <= TCP_COOKIE_MIN) { 403bd0388aeSWilliam Allen Simpson /* value too small, specify minimum */ 404bd0388aeSWilliam Allen Simpson return TCP_COOKIE_MIN; 405bd0388aeSWilliam Allen Simpson } 406bd0388aeSWilliam Allen Simpson if (sysctl_tcp_cookie_size >= TCP_COOKIE_MAX) { 407bd0388aeSWilliam Allen Simpson /* value too large, specify maximum */ 408bd0388aeSWilliam Allen Simpson return TCP_COOKIE_MAX; 409bd0388aeSWilliam Allen Simpson } 410bd0388aeSWilliam Allen Simpson if (0x1 & sysctl_tcp_cookie_size) { 411bd0388aeSWilliam Allen Simpson /* 8-bit multiple, illegal, fix it */ 412bd0388aeSWilliam Allen Simpson return (u8)(sysctl_tcp_cookie_size + 0x1); 413bd0388aeSWilliam Allen Simpson } 414bd0388aeSWilliam Allen Simpson return (u8)sysctl_tcp_cookie_size; 415bd0388aeSWilliam Allen Simpson } 416bd0388aeSWilliam Allen Simpson 41767edfef7SAndi Kleen /* Write previously computed TCP options to the packet. 41867edfef7SAndi Kleen * 41967edfef7SAndi Kleen * Beware: Something in the Internet is very sensitive to the ordering of 420fd6149d3SIlpo Järvinen * TCP options, we learned this through the hard way, so be careful here. 421fd6149d3SIlpo Järvinen * Luckily we can at least blame others for their non-compliance but from 422fd6149d3SIlpo Järvinen * inter-operatibility perspective it seems that we're somewhat stuck with 423fd6149d3SIlpo Järvinen * the ordering which we have been using if we want to keep working with 424fd6149d3SIlpo Järvinen * those broken things (not that it currently hurts anybody as there isn't 425fd6149d3SIlpo Järvinen * particular reason why the ordering would need to be changed). 426fd6149d3SIlpo Järvinen * 427fd6149d3SIlpo Järvinen * At least SACK_PERM as the first option is known to lead to a disaster 428fd6149d3SIlpo Järvinen * (but it may well be that other scenarios fail similarly). 429fd6149d3SIlpo Järvinen */ 43033ad798cSAdam Langley static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, 431bd0388aeSWilliam Allen Simpson struct tcp_out_options *opts) 432bd0388aeSWilliam Allen Simpson { 433bd0388aeSWilliam Allen Simpson u8 options = opts->options; /* mungable copy */ 434bd0388aeSWilliam Allen Simpson 435bd0388aeSWilliam Allen Simpson /* Having both authentication and cookies for security is redundant, 436bd0388aeSWilliam Allen Simpson * and there's certainly not enough room. Instead, the cookie-less 437bd0388aeSWilliam Allen Simpson * extension variant is proposed. 438bd0388aeSWilliam Allen Simpson * 439bd0388aeSWilliam Allen Simpson * Consider the pessimal case with authentication. The options 440bd0388aeSWilliam Allen Simpson * could look like: 441bd0388aeSWilliam Allen Simpson * COOKIE|MD5(20) + MSS(4) + SACK|TS(12) + WSCALE(4) == 40 442bd0388aeSWilliam Allen Simpson */ 443bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_MD5 & options)) { 444bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_COOKIE_EXTENSION & options)) { 445bd0388aeSWilliam Allen Simpson *ptr++ = htonl((TCPOPT_COOKIE << 24) | 446bd0388aeSWilliam Allen Simpson (TCPOLEN_COOKIE_BASE << 16) | 447bd0388aeSWilliam Allen Simpson (TCPOPT_MD5SIG << 8) | 448bd0388aeSWilliam Allen Simpson TCPOLEN_MD5SIG); 449bd0388aeSWilliam Allen Simpson } else { 45033ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 45133ad798cSAdam Langley (TCPOPT_NOP << 16) | 45233ad798cSAdam Langley (TCPOPT_MD5SIG << 8) | 45333ad798cSAdam Langley TCPOLEN_MD5SIG); 454bd0388aeSWilliam Allen Simpson } 455bd0388aeSWilliam Allen Simpson options &= ~OPTION_COOKIE_EXTENSION; 456bd0388aeSWilliam Allen Simpson /* overload cookie hash location */ 457bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)ptr; 45833ad798cSAdam Langley ptr += 4; 45933ad798cSAdam Langley } 46033ad798cSAdam Langley 461fd6149d3SIlpo Järvinen if (unlikely(opts->mss)) { 462fd6149d3SIlpo Järvinen *ptr++ = htonl((TCPOPT_MSS << 24) | 463fd6149d3SIlpo Järvinen (TCPOLEN_MSS << 16) | 464fd6149d3SIlpo Järvinen opts->mss); 465fd6149d3SIlpo Järvinen } 466fd6149d3SIlpo Järvinen 467bd0388aeSWilliam Allen Simpson if (likely(OPTION_TS & options)) { 468bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 46933ad798cSAdam Langley *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | 47033ad798cSAdam Langley (TCPOLEN_SACK_PERM << 16) | 47133ad798cSAdam Langley (TCPOPT_TIMESTAMP << 8) | 47233ad798cSAdam Langley TCPOLEN_TIMESTAMP); 473bd0388aeSWilliam Allen Simpson options &= ~OPTION_SACK_ADVERTISE; 47433ad798cSAdam Langley } else { 475496c98dfSYOSHIFUJI Hideaki *ptr++ = htonl((TCPOPT_NOP << 24) | 47640efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 47740efc6faSStephen Hemminger (TCPOPT_TIMESTAMP << 8) | 47840efc6faSStephen Hemminger TCPOLEN_TIMESTAMP); 47940efc6faSStephen Hemminger } 48033ad798cSAdam Langley *ptr++ = htonl(opts->tsval); 48133ad798cSAdam Langley *ptr++ = htonl(opts->tsecr); 48233ad798cSAdam Langley } 48333ad798cSAdam Langley 484bd0388aeSWilliam Allen Simpson /* Specification requires after timestamp, so do it now. 485bd0388aeSWilliam Allen Simpson * 486bd0388aeSWilliam Allen Simpson * Consider the pessimal case without authentication. The options 487bd0388aeSWilliam Allen Simpson * could look like: 488bd0388aeSWilliam Allen Simpson * MSS(4) + SACK|TS(12) + COOKIE(20) + WSCALE(4) == 40 489bd0388aeSWilliam Allen Simpson */ 490bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_COOKIE_EXTENSION & options)) { 491bd0388aeSWilliam Allen Simpson __u8 *cookie_copy = opts->hash_location; 492bd0388aeSWilliam Allen Simpson u8 cookie_size = opts->hash_size; 493bd0388aeSWilliam Allen Simpson 494bd0388aeSWilliam Allen Simpson /* 8-bit multiple handled in tcp_cookie_size_check() above, 495bd0388aeSWilliam Allen Simpson * and elsewhere. 496bd0388aeSWilliam Allen Simpson */ 497bd0388aeSWilliam Allen Simpson if (0x2 & cookie_size) { 498bd0388aeSWilliam Allen Simpson __u8 *p = (__u8 *)ptr; 499bd0388aeSWilliam Allen Simpson 500bd0388aeSWilliam Allen Simpson /* 16-bit multiple */ 501bd0388aeSWilliam Allen Simpson *p++ = TCPOPT_COOKIE; 502bd0388aeSWilliam Allen Simpson *p++ = TCPOLEN_COOKIE_BASE + cookie_size; 503bd0388aeSWilliam Allen Simpson *p++ = *cookie_copy++; 504bd0388aeSWilliam Allen Simpson *p++ = *cookie_copy++; 505bd0388aeSWilliam Allen Simpson ptr++; 506bd0388aeSWilliam Allen Simpson cookie_size -= 2; 507bd0388aeSWilliam Allen Simpson } else { 508bd0388aeSWilliam Allen Simpson /* 32-bit multiple */ 509bd0388aeSWilliam Allen Simpson *ptr++ = htonl(((TCPOPT_NOP << 24) | 510bd0388aeSWilliam Allen Simpson (TCPOPT_NOP << 16) | 511bd0388aeSWilliam Allen Simpson (TCPOPT_COOKIE << 8) | 512bd0388aeSWilliam Allen Simpson TCPOLEN_COOKIE_BASE) + 513bd0388aeSWilliam Allen Simpson cookie_size); 514bd0388aeSWilliam Allen Simpson } 515bd0388aeSWilliam Allen Simpson 516bd0388aeSWilliam Allen Simpson if (cookie_size > 0) { 517bd0388aeSWilliam Allen Simpson memcpy(ptr, cookie_copy, cookie_size); 518bd0388aeSWilliam Allen Simpson ptr += (cookie_size / 4); 519bd0388aeSWilliam Allen Simpson } 520bd0388aeSWilliam Allen Simpson } 521bd0388aeSWilliam Allen Simpson 522bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_SACK_ADVERTISE & options)) { 52333ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 52433ad798cSAdam Langley (TCPOPT_NOP << 16) | 52533ad798cSAdam Langley (TCPOPT_SACK_PERM << 8) | 52633ad798cSAdam Langley TCPOLEN_SACK_PERM); 52733ad798cSAdam Langley } 52833ad798cSAdam Langley 529bd0388aeSWilliam Allen Simpson if (unlikely(OPTION_WSCALE & options)) { 53033ad798cSAdam Langley *ptr++ = htonl((TCPOPT_NOP << 24) | 53133ad798cSAdam Langley (TCPOPT_WINDOW << 16) | 53233ad798cSAdam Langley (TCPOLEN_WINDOW << 8) | 53333ad798cSAdam Langley opts->ws); 53433ad798cSAdam Langley } 53533ad798cSAdam Langley 53633ad798cSAdam Langley if (unlikely(opts->num_sack_blocks)) { 53733ad798cSAdam Langley struct tcp_sack_block *sp = tp->rx_opt.dsack ? 53833ad798cSAdam Langley tp->duplicate_sack : tp->selective_acks; 53940efc6faSStephen Hemminger int this_sack; 54040efc6faSStephen Hemminger 54140efc6faSStephen Hemminger *ptr++ = htonl((TCPOPT_NOP << 24) | 54240efc6faSStephen Hemminger (TCPOPT_NOP << 16) | 54340efc6faSStephen Hemminger (TCPOPT_SACK << 8) | 54433ad798cSAdam Langley (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * 54540efc6faSStephen Hemminger TCPOLEN_SACK_PERBLOCK))); 5462de979bdSStephen Hemminger 54733ad798cSAdam Langley for (this_sack = 0; this_sack < opts->num_sack_blocks; 54833ad798cSAdam Langley ++this_sack) { 54940efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].start_seq); 55040efc6faSStephen Hemminger *ptr++ = htonl(sp[this_sack].end_seq); 55140efc6faSStephen Hemminger } 5522de979bdSStephen Hemminger 55340efc6faSStephen Hemminger tp->rx_opt.dsack = 0; 55440efc6faSStephen Hemminger } 55540efc6faSStephen Hemminger } 55640efc6faSStephen Hemminger 55767edfef7SAndi Kleen /* Compute TCP options for SYN packets. This is not the final 55867edfef7SAndi Kleen * network wire format yet. 55967edfef7SAndi Kleen */ 56033ad798cSAdam Langley static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb, 56133ad798cSAdam Langley struct tcp_out_options *opts, 56233ad798cSAdam Langley struct tcp_md5sig_key **md5) { 56333ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 564bd0388aeSWilliam Allen Simpson struct tcp_cookie_values *cvp = tp->cookie_values; 565bd0388aeSWilliam Allen Simpson unsigned remaining = MAX_TCP_OPTION_SPACE; 566bd0388aeSWilliam Allen Simpson u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ? 567bd0388aeSWilliam Allen Simpson tcp_cookie_size_check(cvp->cookie_desired) : 568bd0388aeSWilliam Allen Simpson 0; 56933ad798cSAdam Langley 570cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 57133ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 57233ad798cSAdam Langley if (*md5) { 57333ad798cSAdam Langley opts->options |= OPTION_MD5; 574bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 575cfb6eeb4SYOSHIFUJI Hideaki } 57633ad798cSAdam Langley #else 57733ad798cSAdam Langley *md5 = NULL; 578cfb6eeb4SYOSHIFUJI Hideaki #endif 57933ad798cSAdam Langley 58033ad798cSAdam Langley /* We always get an MSS option. The option bytes which will be seen in 58133ad798cSAdam Langley * normal data packets should timestamps be used, must be in the MSS 58233ad798cSAdam Langley * advertised. But we subtract them from tp->mss_cache so that 58333ad798cSAdam Langley * calculations in tcp_sendmsg are simpler etc. So account for this 58433ad798cSAdam Langley * fact here if necessary. If we don't do this correctly, as a 58533ad798cSAdam Langley * receiver we won't recognize data packets as being full sized when we 58633ad798cSAdam Langley * should, and thus we won't abide by the delayed ACK rules correctly. 58733ad798cSAdam Langley * SACKs don't matter, we never delay an ACK when we have any of those 58833ad798cSAdam Langley * going out. */ 58933ad798cSAdam Langley opts->mss = tcp_advertise_mss(sk); 590bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 59133ad798cSAdam Langley 592bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_timestamps && *md5 == NULL)) { 59333ad798cSAdam Langley opts->options |= OPTION_TS; 59433ad798cSAdam Langley opts->tsval = TCP_SKB_CB(skb)->when; 59533ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 596bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 59733ad798cSAdam Langley } 598bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_window_scaling)) { 59933ad798cSAdam Langley opts->ws = tp->rx_opt.rcv_wscale; 60089e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 601bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 60233ad798cSAdam Langley } 603bb5b7c11SDavid S. Miller if (likely(sysctl_tcp_sack)) { 60433ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 605b32d1310SDavid S. Miller if (unlikely(!(OPTION_TS & opts->options))) 606bd0388aeSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 60733ad798cSAdam Langley } 60833ad798cSAdam Langley 609bd0388aeSWilliam Allen Simpson /* Note that timestamps are required by the specification. 610bd0388aeSWilliam Allen Simpson * 611bd0388aeSWilliam Allen Simpson * Odd numbers of bytes are prohibited by the specification, ensuring 612bd0388aeSWilliam Allen Simpson * that the cookie is 16-bit aligned, and the resulting cookie pair is 613bd0388aeSWilliam Allen Simpson * 32-bit aligned. 614bd0388aeSWilliam Allen Simpson */ 615bd0388aeSWilliam Allen Simpson if (*md5 == NULL && 616bd0388aeSWilliam Allen Simpson (OPTION_TS & opts->options) && 617bd0388aeSWilliam Allen Simpson cookie_size > 0) { 618bd0388aeSWilliam Allen Simpson int need = TCPOLEN_COOKIE_BASE + cookie_size; 619bd0388aeSWilliam Allen Simpson 620bd0388aeSWilliam Allen Simpson if (0x2 & need) { 621bd0388aeSWilliam Allen Simpson /* 32-bit multiple */ 622bd0388aeSWilliam Allen Simpson need += 2; /* NOPs */ 623bd0388aeSWilliam Allen Simpson 624bd0388aeSWilliam Allen Simpson if (need > remaining) { 625bd0388aeSWilliam Allen Simpson /* try shrinking cookie to fit */ 626bd0388aeSWilliam Allen Simpson cookie_size -= 2; 627bd0388aeSWilliam Allen Simpson need -= 4; 628bd0388aeSWilliam Allen Simpson } 629bd0388aeSWilliam Allen Simpson } 630bd0388aeSWilliam Allen Simpson while (need > remaining && TCP_COOKIE_MIN <= cookie_size) { 631bd0388aeSWilliam Allen Simpson cookie_size -= 4; 632bd0388aeSWilliam Allen Simpson need -= 4; 633bd0388aeSWilliam Allen Simpson } 634bd0388aeSWilliam Allen Simpson if (TCP_COOKIE_MIN <= cookie_size) { 635bd0388aeSWilliam Allen Simpson opts->options |= OPTION_COOKIE_EXTENSION; 636bd0388aeSWilliam Allen Simpson opts->hash_location = (__u8 *)&cvp->cookie_pair[0]; 637bd0388aeSWilliam Allen Simpson opts->hash_size = cookie_size; 638bd0388aeSWilliam Allen Simpson 639bd0388aeSWilliam Allen Simpson /* Remember for future incarnations. */ 640bd0388aeSWilliam Allen Simpson cvp->cookie_desired = cookie_size; 641bd0388aeSWilliam Allen Simpson 642bd0388aeSWilliam Allen Simpson if (cvp->cookie_desired != cvp->cookie_pair_size) { 643bd0388aeSWilliam Allen Simpson /* Currently use random bytes as a nonce, 644bd0388aeSWilliam Allen Simpson * assuming these are completely unpredictable 645bd0388aeSWilliam Allen Simpson * by hostile users of the same system. 646bd0388aeSWilliam Allen Simpson */ 647bd0388aeSWilliam Allen Simpson get_random_bytes(&cvp->cookie_pair[0], 648bd0388aeSWilliam Allen Simpson cookie_size); 649bd0388aeSWilliam Allen Simpson cvp->cookie_pair_size = cookie_size; 650bd0388aeSWilliam Allen Simpson } 651bd0388aeSWilliam Allen Simpson 652bd0388aeSWilliam Allen Simpson remaining -= need; 653bd0388aeSWilliam Allen Simpson } 654bd0388aeSWilliam Allen Simpson } 655bd0388aeSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 65633ad798cSAdam Langley } 65733ad798cSAdam Langley 65867edfef7SAndi Kleen /* Set up TCP options for SYN-ACKs. */ 65933ad798cSAdam Langley static unsigned tcp_synack_options(struct sock *sk, 66033ad798cSAdam Langley struct request_sock *req, 66133ad798cSAdam Langley unsigned mss, struct sk_buff *skb, 66233ad798cSAdam Langley struct tcp_out_options *opts, 6634957faadSWilliam Allen Simpson struct tcp_md5sig_key **md5, 6644957faadSWilliam Allen Simpson struct tcp_extend_values *xvp) 6654957faadSWilliam Allen Simpson { 66633ad798cSAdam Langley struct inet_request_sock *ireq = inet_rsk(req); 6674957faadSWilliam Allen Simpson unsigned remaining = MAX_TCP_OPTION_SPACE; 6684957faadSWilliam Allen Simpson u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ? 6694957faadSWilliam Allen Simpson xvp->cookie_plus : 6704957faadSWilliam Allen Simpson 0; 67133ad798cSAdam Langley 67233ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 67333ad798cSAdam Langley *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); 67433ad798cSAdam Langley if (*md5) { 67533ad798cSAdam Langley opts->options |= OPTION_MD5; 6764957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6774957faadSWilliam Allen Simpson 6784957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6794957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6804957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6814957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6824957faadSWilliam Allen Simpson */ 683de213e5eSEric Dumazet ireq->tstamp_ok &= !ireq->sack_ok; 68433ad798cSAdam Langley } 68533ad798cSAdam Langley #else 68633ad798cSAdam Langley *md5 = NULL; 68733ad798cSAdam Langley #endif 68833ad798cSAdam Langley 6894957faadSWilliam Allen Simpson /* We always send an MSS option. */ 69033ad798cSAdam Langley opts->mss = mss; 6914957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 69233ad798cSAdam Langley 69333ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 69433ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 69589e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6964957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 69733ad798cSAdam Langley } 698de213e5eSEric Dumazet if (likely(ireq->tstamp_ok)) { 69933ad798cSAdam Langley opts->options |= OPTION_TS; 70033ad798cSAdam Langley opts->tsval = TCP_SKB_CB(skb)->when; 70133ad798cSAdam Langley opts->tsecr = req->ts_recent; 7024957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 70333ad798cSAdam Langley } 70433ad798cSAdam Langley if (likely(ireq->sack_ok)) { 70533ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 706de213e5eSEric Dumazet if (unlikely(!ireq->tstamp_ok)) 7074957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 70833ad798cSAdam Langley } 70933ad798cSAdam Langley 7104957faadSWilliam Allen Simpson /* Similar rationale to tcp_syn_options() applies here, too. 7114957faadSWilliam Allen Simpson * If the <SYN> options fit, the same options should fit now! 7124957faadSWilliam Allen Simpson */ 7134957faadSWilliam Allen Simpson if (*md5 == NULL && 714de213e5eSEric Dumazet ireq->tstamp_ok && 7154957faadSWilliam Allen Simpson cookie_plus > TCPOLEN_COOKIE_BASE) { 7164957faadSWilliam Allen Simpson int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */ 7174957faadSWilliam Allen Simpson 7184957faadSWilliam Allen Simpson if (0x2 & need) { 7194957faadSWilliam Allen Simpson /* 32-bit multiple */ 7204957faadSWilliam Allen Simpson need += 2; /* NOPs */ 7214957faadSWilliam Allen Simpson } 7224957faadSWilliam Allen Simpson if (need <= remaining) { 7234957faadSWilliam Allen Simpson opts->options |= OPTION_COOKIE_EXTENSION; 7244957faadSWilliam Allen Simpson opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE; 7254957faadSWilliam Allen Simpson remaining -= need; 7264957faadSWilliam Allen Simpson } else { 7274957faadSWilliam Allen Simpson /* There's no error return, so flag it. */ 7284957faadSWilliam Allen Simpson xvp->cookie_out_never = 1; /* true */ 7294957faadSWilliam Allen Simpson opts->hash_size = 0; 7304957faadSWilliam Allen Simpson } 7314957faadSWilliam Allen Simpson } 7324957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 73333ad798cSAdam Langley } 73433ad798cSAdam Langley 73567edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 73667edfef7SAndi Kleen * final wire format yet. 73767edfef7SAndi Kleen */ 73833ad798cSAdam Langley static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb, 73933ad798cSAdam Langley struct tcp_out_options *opts, 74033ad798cSAdam Langley struct tcp_md5sig_key **md5) { 74133ad798cSAdam Langley struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; 74233ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 74333ad798cSAdam Langley unsigned size = 0; 744cabeccbdSIlpo Järvinen unsigned int eff_sacks; 74533ad798cSAdam Langley 74633ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 74733ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 74833ad798cSAdam Langley if (unlikely(*md5)) { 74933ad798cSAdam Langley opts->options |= OPTION_MD5; 75033ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 75133ad798cSAdam Langley } 75233ad798cSAdam Langley #else 75333ad798cSAdam Langley *md5 = NULL; 75433ad798cSAdam Langley #endif 75533ad798cSAdam Langley 75633ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 75733ad798cSAdam Langley opts->options |= OPTION_TS; 75833ad798cSAdam Langley opts->tsval = tcb ? tcb->when : 0; 75933ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 76033ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 76133ad798cSAdam Langley } 76233ad798cSAdam Langley 763cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 764cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 76533ad798cSAdam Langley const unsigned remaining = MAX_TCP_OPTION_SPACE - size; 76633ad798cSAdam Langley opts->num_sack_blocks = 767cabeccbdSIlpo Järvinen min_t(unsigned, eff_sacks, 76833ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 76933ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 77033ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 77133ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 77233ad798cSAdam Langley } 77333ad798cSAdam Langley 77433ad798cSAdam Langley return size; 77540efc6faSStephen Hemminger } 7761da177e4SLinus Torvalds 7771da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 7781da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 7791da177e4SLinus Torvalds * transmission and possible later retransmissions. 7801da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 7811da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 7821da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 7831da177e4SLinus Torvalds * device. 7841da177e4SLinus Torvalds * 7851da177e4SLinus Torvalds * We are working here with either a clone of the original 7861da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 7871da177e4SLinus Torvalds */ 788056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 789056834d9SIlpo Järvinen gfp_t gfp_mask) 7901da177e4SLinus Torvalds { 7916687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 792dfb4b9dcSDavid S. Miller struct inet_sock *inet; 793dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 794dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 79533ad798cSAdam Langley struct tcp_out_options opts; 79633ad798cSAdam Langley unsigned tcp_options_size, tcp_header_size; 797cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 7981da177e4SLinus Torvalds struct tcphdr *th; 7991da177e4SLinus Torvalds int err; 8001da177e4SLinus Torvalds 801dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 802dfb4b9dcSDavid S. Miller 803dfb4b9dcSDavid S. Miller /* If congestion control is doing timestamping, we must 804dfb4b9dcSDavid S. Miller * take such a timestamp before we potentially clone/copy. 805dfb4b9dcSDavid S. Miller */ 806164891aaSStephen Hemminger if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) 807dfb4b9dcSDavid S. Miller __net_timestamp(skb); 808dfb4b9dcSDavid S. Miller 809dfb4b9dcSDavid S. Miller if (likely(clone_it)) { 810dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 811dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 812dfb4b9dcSDavid S. Miller else 813dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 814dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 815dfb4b9dcSDavid S. Miller return -ENOBUFS; 816dfb4b9dcSDavid S. Miller } 817dfb4b9dcSDavid S. Miller 818dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 819dfb4b9dcSDavid S. Miller tp = tcp_sk(sk); 820dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 82133ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 8221da177e4SLinus Torvalds 823a3433f35SChangli Gao if (unlikely(tcb->flags & TCPHDR_SYN)) 82433ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 82533ad798cSAdam Langley else 82633ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 82733ad798cSAdam Langley &md5); 82833ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 8291da177e4SLinus Torvalds 830317a76f9SStephen Hemminger if (tcp_packets_in_flight(tp) == 0) 8316687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_TX_START); 8321da177e4SLinus Torvalds 833aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 834aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 835e89862f4SDavid S. Miller skb_set_owner_w(skb, sk); 8361da177e4SLinus Torvalds 8371da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 838aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 839c720c7e8SEric Dumazet th->source = inet->inet_sport; 840c720c7e8SEric Dumazet th->dest = inet->inet_dport; 8411da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 8421da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 843df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 844dfb4b9dcSDavid S. Miller tcb->flags); 845dfb4b9dcSDavid S. Miller 846a3433f35SChangli Gao if (unlikely(tcb->flags & TCPHDR_SYN)) { 8471da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 8481da177e4SLinus Torvalds * is never scaled. 8491da177e4SLinus Torvalds */ 850600ff0c2SIlpo Järvinen th->window = htons(min(tp->rcv_wnd, 65535U)); 8511da177e4SLinus Torvalds } else { 8521da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 8531da177e4SLinus Torvalds } 8541da177e4SLinus Torvalds th->check = 0; 8551da177e4SLinus Torvalds th->urg_ptr = 0; 8561da177e4SLinus Torvalds 85733f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 8587691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 8597691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 8601da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 8611da177e4SLinus Torvalds th->urg = 1; 8627691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 8630eae88f3SEric Dumazet th->urg_ptr = htons(0xFFFF); 8647691367dSHerbert Xu th->urg = 1; 8657691367dSHerbert Xu } 8661da177e4SLinus Torvalds } 8671da177e4SLinus Torvalds 868bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 869a3433f35SChangli Gao if (likely((tcb->flags & TCPHDR_SYN) == 0)) 8709e412ba7SIlpo Järvinen TCP_ECN_send(sk, skb, tcp_header_size); 871dfb4b9dcSDavid S. Miller 872cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 873cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 874cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 875a465419bSEric Dumazet sk_nocaps_add(sk, NETIF_F_GSO_MASK); 876bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 87749a72dfbSAdam Langley md5, sk, NULL, skb); 878cfb6eeb4SYOSHIFUJI Hideaki } 879cfb6eeb4SYOSHIFUJI Hideaki #endif 880cfb6eeb4SYOSHIFUJI Hideaki 881bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 8821da177e4SLinus Torvalds 883a3433f35SChangli Gao if (likely(tcb->flags & TCPHDR_ACK)) 884fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 8851da177e4SLinus Torvalds 8861da177e4SLinus Torvalds if (skb->len != tcp_header_size) 8871da177e4SLinus Torvalds tcp_event_data_sent(tp, skb, sk); 8881da177e4SLinus Torvalds 889bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 890aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, 891aa2ea058STom Herbert tcp_skb_pcount(skb)); 8921da177e4SLinus Torvalds 8934e15ed4dSShan Wei err = icsk->icsk_af_ops->queue_xmit(skb); 89483de47cdSHua Zhong if (likely(err <= 0)) 8951da177e4SLinus Torvalds return err; 8961da177e4SLinus Torvalds 8973cfe3baaSIlpo Järvinen tcp_enter_cwr(sk, 1); 8981da177e4SLinus Torvalds 899b9df3cb8SGerrit Renker return net_xmit_eval(err); 9001da177e4SLinus Torvalds } 9011da177e4SLinus Torvalds 90267edfef7SAndi Kleen /* This routine just queues the buffer for sending. 9031da177e4SLinus Torvalds * 9041da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 9051da177e4SLinus Torvalds * otherwise socket can stall. 9061da177e4SLinus Torvalds */ 9071da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 9081da177e4SLinus Torvalds { 9091da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 9101da177e4SLinus Torvalds 9111da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 9121da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 9131da177e4SLinus Torvalds skb_header_release(skb); 914fe067e8aSDavid S. Miller tcp_add_write_queue_tail(sk, skb); 9153ab224beSHideo Aoki sk->sk_wmem_queued += skb->truesize; 9163ab224beSHideo Aoki sk_mem_charge(sk, skb->truesize); 9171da177e4SLinus Torvalds } 9181da177e4SLinus Torvalds 91967edfef7SAndi Kleen /* Initialize TSO segments for a packet. */ 920056834d9SIlpo Järvinen static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, 921056834d9SIlpo Järvinen unsigned int mss_now) 922f6302d1dSDavid S. Miller { 9238e5b9ddaSHerbert Xu if (skb->len <= mss_now || !sk_can_gso(sk) || 9248e5b9ddaSHerbert Xu skb->ip_summed == CHECKSUM_NONE) { 925f6302d1dSDavid S. Miller /* Avoid the costly divide in the normal 926f6302d1dSDavid S. Miller * non-TSO case. 927f6302d1dSDavid S. Miller */ 9287967168cSHerbert Xu skb_shinfo(skb)->gso_segs = 1; 9297967168cSHerbert Xu skb_shinfo(skb)->gso_size = 0; 9307967168cSHerbert Xu skb_shinfo(skb)->gso_type = 0; 931f6302d1dSDavid S. Miller } else { 932356f89e1SIlpo Järvinen skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now); 9337967168cSHerbert Xu skb_shinfo(skb)->gso_size = mss_now; 934bcd76111SHerbert Xu skb_shinfo(skb)->gso_type = sk->sk_gso_type; 9351da177e4SLinus Torvalds } 9361da177e4SLinus Torvalds } 9371da177e4SLinus Torvalds 93891fed7a1SIlpo Järvinen /* When a modification to fackets out becomes necessary, we need to check 93968f8353bSIlpo Järvinen * skb is counted to fackets_out or not. 94091fed7a1SIlpo Järvinen */ 941a47e5a98SIlpo Järvinen static void tcp_adjust_fackets_out(struct sock *sk, struct sk_buff *skb, 94291fed7a1SIlpo Järvinen int decr) 94391fed7a1SIlpo Järvinen { 944a47e5a98SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 945a47e5a98SIlpo Järvinen 946dc86967bSIlpo Järvinen if (!tp->sacked_out || tcp_is_reno(tp)) 94791fed7a1SIlpo Järvinen return; 94891fed7a1SIlpo Järvinen 9496859d494SIlpo Järvinen if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) 95091fed7a1SIlpo Järvinen tp->fackets_out -= decr; 95191fed7a1SIlpo Järvinen } 95291fed7a1SIlpo Järvinen 953797108d1SIlpo Järvinen /* Pcount in the middle of the write queue got changed, we need to do various 954797108d1SIlpo Järvinen * tweaks to fix counters 955797108d1SIlpo Järvinen */ 956797108d1SIlpo Järvinen static void tcp_adjust_pcount(struct sock *sk, struct sk_buff *skb, int decr) 957797108d1SIlpo Järvinen { 958797108d1SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 959797108d1SIlpo Järvinen 960797108d1SIlpo Järvinen tp->packets_out -= decr; 961797108d1SIlpo Järvinen 962797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 963797108d1SIlpo Järvinen tp->sacked_out -= decr; 964797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) 965797108d1SIlpo Järvinen tp->retrans_out -= decr; 966797108d1SIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) 967797108d1SIlpo Järvinen tp->lost_out -= decr; 968797108d1SIlpo Järvinen 969797108d1SIlpo Järvinen /* Reno case is special. Sigh... */ 970797108d1SIlpo Järvinen if (tcp_is_reno(tp) && decr > 0) 971797108d1SIlpo Järvinen tp->sacked_out -= min_t(u32, tp->sacked_out, decr); 972797108d1SIlpo Järvinen 973797108d1SIlpo Järvinen tcp_adjust_fackets_out(sk, skb, decr); 974797108d1SIlpo Järvinen 975797108d1SIlpo Järvinen if (tp->lost_skb_hint && 976797108d1SIlpo Järvinen before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && 97752cf3cc8SIlpo Järvinen (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) 978797108d1SIlpo Järvinen tp->lost_cnt_hint -= decr; 979797108d1SIlpo Järvinen 980797108d1SIlpo Järvinen tcp_verify_left_out(tp); 981797108d1SIlpo Järvinen } 982797108d1SIlpo Järvinen 9831da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 9841da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 9851da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 9861da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 9871da177e4SLinus Torvalds */ 988056834d9SIlpo Järvinen int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 989056834d9SIlpo Järvinen unsigned int mss_now) 9901da177e4SLinus Torvalds { 9911da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 9921da177e4SLinus Torvalds struct sk_buff *buff; 9936475be16SDavid S. Miller int nsize, old_factor; 994b60b49eaSHerbert Xu int nlen; 9959ce01461SIlpo Järvinen u8 flags; 9961da177e4SLinus Torvalds 997b2cc99f0SHerbert Xu BUG_ON(len > skb->len); 9986a438bbeSStephen Hemminger 9991da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 10001da177e4SLinus Torvalds if (nsize < 0) 10011da177e4SLinus Torvalds nsize = 0; 10021da177e4SLinus Torvalds 10031da177e4SLinus Torvalds if (skb_cloned(skb) && 10041da177e4SLinus Torvalds skb_is_nonlinear(skb) && 10051da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 10061da177e4SLinus Torvalds return -ENOMEM; 10071da177e4SLinus Torvalds 10081da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 10091da177e4SLinus Torvalds buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); 10101da177e4SLinus Torvalds if (buff == NULL) 10111da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 1012ef5cb973SHerbert Xu 10133ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 10143ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1015b60b49eaSHerbert Xu nlen = skb->len - len - nsize; 1016b60b49eaSHerbert Xu buff->truesize += nlen; 1017b60b49eaSHerbert Xu skb->truesize -= nlen; 10181da177e4SLinus Torvalds 10191da177e4SLinus Torvalds /* Correct the sequence numbers. */ 10201da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 10211da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 10221da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 10231da177e4SLinus Torvalds 10241da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 10251da177e4SLinus Torvalds flags = TCP_SKB_CB(skb)->flags; 1026a3433f35SChangli Gao TCP_SKB_CB(skb)->flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 10271da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = flags; 1028e14c3cafSHerbert Xu TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; 10291da177e4SLinus Torvalds 103084fa7933SPatrick McHardy if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { 10311da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 1032056834d9SIlpo Järvinen buff->csum = csum_partial_copy_nocheck(skb->data + len, 1033056834d9SIlpo Järvinen skb_put(buff, nsize), 10341da177e4SLinus Torvalds nsize, 0); 10351da177e4SLinus Torvalds 10361da177e4SLinus Torvalds skb_trim(skb, len); 10371da177e4SLinus Torvalds 10381da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 10391da177e4SLinus Torvalds } else { 104084fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 10411da177e4SLinus Torvalds skb_split(skb, buff, len); 10421da177e4SLinus Torvalds } 10431da177e4SLinus Torvalds 10441da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 10451da177e4SLinus Torvalds 10461da177e4SLinus Torvalds /* Looks stupid, but our code really uses when of 10471da177e4SLinus Torvalds * skbs, which it never sent before. --ANK 10481da177e4SLinus Torvalds */ 10491da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; 1050a61bbcf2SPatrick McHardy buff->tstamp = skb->tstamp; 10511da177e4SLinus Torvalds 10526475be16SDavid S. Miller old_factor = tcp_skb_pcount(skb); 10536475be16SDavid S. Miller 10541da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 1055846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1056846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 10571da177e4SLinus Torvalds 10586475be16SDavid S. Miller /* If this packet has been sent out already, we must 10596475be16SDavid S. Miller * adjust the various packet counters. 10606475be16SDavid S. Miller */ 1061cf0b450cSHerbert Xu if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { 10626475be16SDavid S. Miller int diff = old_factor - tcp_skb_pcount(skb) - 10636475be16SDavid S. Miller tcp_skb_pcount(buff); 10641da177e4SLinus Torvalds 1065797108d1SIlpo Järvinen if (diff) 1066797108d1SIlpo Järvinen tcp_adjust_pcount(sk, skb, diff); 10671da177e4SLinus Torvalds } 10681da177e4SLinus Torvalds 10691da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 1070f44b5271SDavid S. Miller skb_header_release(buff); 1071fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 10721da177e4SLinus Torvalds 10731da177e4SLinus Torvalds return 0; 10741da177e4SLinus Torvalds } 10751da177e4SLinus Torvalds 10761da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 10771da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 10781da177e4SLinus Torvalds * immediately discarded. 10791da177e4SLinus Torvalds */ 1080f2911969SHerbert Xu ~{PmVHI~} static void __pskb_trim_head(struct sk_buff *skb, int len) 10811da177e4SLinus Torvalds { 10821da177e4SLinus Torvalds int i, k, eat; 10831da177e4SLinus Torvalds 10841da177e4SLinus Torvalds eat = len; 10851da177e4SLinus Torvalds k = 0; 10861da177e4SLinus Torvalds for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { 10871da177e4SLinus Torvalds if (skb_shinfo(skb)->frags[i].size <= eat) { 10881da177e4SLinus Torvalds put_page(skb_shinfo(skb)->frags[i].page); 10891da177e4SLinus Torvalds eat -= skb_shinfo(skb)->frags[i].size; 10901da177e4SLinus Torvalds } else { 10911da177e4SLinus Torvalds skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 10921da177e4SLinus Torvalds if (eat) { 10931da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].page_offset += eat; 10941da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].size -= eat; 10951da177e4SLinus Torvalds eat = 0; 10961da177e4SLinus Torvalds } 10971da177e4SLinus Torvalds k++; 10981da177e4SLinus Torvalds } 10991da177e4SLinus Torvalds } 11001da177e4SLinus Torvalds skb_shinfo(skb)->nr_frags = k; 11011da177e4SLinus Torvalds 110227a884dcSArnaldo Carvalho de Melo skb_reset_tail_pointer(skb); 11031da177e4SLinus Torvalds skb->data_len -= len; 11041da177e4SLinus Torvalds skb->len = skb->data_len; 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds 110767edfef7SAndi Kleen /* Remove acked data from a packet in the transmit queue. */ 11081da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 11091da177e4SLinus Torvalds { 1110056834d9SIlpo Järvinen if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 11111da177e4SLinus Torvalds return -ENOMEM; 11121da177e4SLinus Torvalds 1113f2911969SHerbert Xu ~{PmVHI~} /* If len == headlen, we avoid __skb_pull to preserve alignment. */ 1114f2911969SHerbert Xu ~{PmVHI~} if (unlikely(len < skb_headlen(skb))) 11151da177e4SLinus Torvalds __skb_pull(skb, len); 1116f2911969SHerbert Xu ~{PmVHI~} else 1117f2911969SHerbert Xu ~{PmVHI~} __pskb_trim_head(skb, len - skb_headlen(skb)); 11181da177e4SLinus Torvalds 11191da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 112084fa7933SPatrick McHardy skb->ip_summed = CHECKSUM_PARTIAL; 11211da177e4SLinus Torvalds 11221da177e4SLinus Torvalds skb->truesize -= len; 11231da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 11243ab224beSHideo Aoki sk_mem_uncharge(sk, len); 11251da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 11261da177e4SLinus Torvalds 11271da177e4SLinus Torvalds /* Any change of skb->len requires recalculation of tso 11281da177e4SLinus Torvalds * factor and mss. 11291da177e4SLinus Torvalds */ 11301da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 11310c54b85fSIlpo Järvinen tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk)); 11321da177e4SLinus Torvalds 11331da177e4SLinus Torvalds return 0; 11341da177e4SLinus Torvalds } 11351da177e4SLinus Torvalds 113667edfef7SAndi Kleen /* Calculate MSS. Not accounting for SACKs here. */ 11375d424d5aSJohn Heffner int tcp_mtu_to_mss(struct sock *sk, int pmtu) 11385d424d5aSJohn Heffner { 11395d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 11405d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 11415d424d5aSJohn Heffner int mss_now; 11425d424d5aSJohn Heffner 11435d424d5aSJohn Heffner /* Calculate base mss without TCP options: 11445d424d5aSJohn Heffner It is MMS_S - sizeof(tcphdr) of rfc1122 11455d424d5aSJohn Heffner */ 11465d424d5aSJohn Heffner mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); 11475d424d5aSJohn Heffner 11485d424d5aSJohn Heffner /* Clamp it (mss_clamp does not include tcp options) */ 11495d424d5aSJohn Heffner if (mss_now > tp->rx_opt.mss_clamp) 11505d424d5aSJohn Heffner mss_now = tp->rx_opt.mss_clamp; 11515d424d5aSJohn Heffner 11525d424d5aSJohn Heffner /* Now subtract optional transport overhead */ 11535d424d5aSJohn Heffner mss_now -= icsk->icsk_ext_hdr_len; 11545d424d5aSJohn Heffner 11555d424d5aSJohn Heffner /* Then reserve room for full set of TCP options and 8 bytes of data */ 11565d424d5aSJohn Heffner if (mss_now < 48) 11575d424d5aSJohn Heffner mss_now = 48; 11585d424d5aSJohn Heffner 11595d424d5aSJohn Heffner /* Now subtract TCP options size, not including SACKs */ 11605d424d5aSJohn Heffner mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); 11615d424d5aSJohn Heffner 11625d424d5aSJohn Heffner return mss_now; 11635d424d5aSJohn Heffner } 11645d424d5aSJohn Heffner 11655d424d5aSJohn Heffner /* Inverse of above */ 11665d424d5aSJohn Heffner int tcp_mss_to_mtu(struct sock *sk, int mss) 11675d424d5aSJohn Heffner { 11685d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 11695d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 11705d424d5aSJohn Heffner int mtu; 11715d424d5aSJohn Heffner 11725d424d5aSJohn Heffner mtu = mss + 11735d424d5aSJohn Heffner tp->tcp_header_len + 11745d424d5aSJohn Heffner icsk->icsk_ext_hdr_len + 11755d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 11765d424d5aSJohn Heffner 11775d424d5aSJohn Heffner return mtu; 11785d424d5aSJohn Heffner } 11795d424d5aSJohn Heffner 118067edfef7SAndi Kleen /* MTU probing init per socket */ 11815d424d5aSJohn Heffner void tcp_mtup_init(struct sock *sk) 11825d424d5aSJohn Heffner { 11835d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 11845d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 11855d424d5aSJohn Heffner 11865d424d5aSJohn Heffner icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; 11875d424d5aSJohn Heffner icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + 11885d424d5aSJohn Heffner icsk->icsk_af_ops->net_header_len; 11895d424d5aSJohn Heffner icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); 11905d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 11915d424d5aSJohn Heffner } 11925d424d5aSJohn Heffner 11931da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 11941da177e4SLinus Torvalds 11951da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 11961da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 11971da177e4SLinus Torvalds 11981da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 1199caa20d9aSStephen Hemminger It is minimum of user_mss and mss received with SYN. 12001da177e4SLinus Torvalds It also does not include TCP options. 12011da177e4SLinus Torvalds 1202d83d8461SArnaldo Carvalho de Melo inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. 12031da177e4SLinus Torvalds 12041da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 12051da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 12061da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 12071da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 12081da177e4SLinus Torvalds 12091da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 12101da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 12111da177e4SLinus Torvalds 1212d83d8461SArnaldo Carvalho de Melo NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache 1213d83d8461SArnaldo Carvalho de Melo are READ ONLY outside this function. --ANK (980731) 12141da177e4SLinus Torvalds */ 12151da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 12161da177e4SLinus Torvalds { 12171da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1218d83d8461SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 12195d424d5aSJohn Heffner int mss_now; 12201da177e4SLinus Torvalds 12215d424d5aSJohn Heffner if (icsk->icsk_mtup.search_high > pmtu) 12225d424d5aSJohn Heffner icsk->icsk_mtup.search_high = pmtu; 12231da177e4SLinus Torvalds 12245d424d5aSJohn Heffner mss_now = tcp_mtu_to_mss(sk, pmtu); 1225409d22b4SIlpo Järvinen mss_now = tcp_bound_to_half_wnd(tp, mss_now); 12261da177e4SLinus Torvalds 12271da177e4SLinus Torvalds /* And store cached results */ 1228d83d8461SArnaldo Carvalho de Melo icsk->icsk_pmtu_cookie = pmtu; 12295d424d5aSJohn Heffner if (icsk->icsk_mtup.enabled) 12305d424d5aSJohn Heffner mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); 1231c1b4a7e6SDavid S. Miller tp->mss_cache = mss_now; 12321da177e4SLinus Torvalds 12331da177e4SLinus Torvalds return mss_now; 12341da177e4SLinus Torvalds } 12351da177e4SLinus Torvalds 12361da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 12371da177e4SLinus Torvalds * and even PMTU discovery events into account. 12381da177e4SLinus Torvalds */ 12390c54b85fSIlpo Järvinen unsigned int tcp_current_mss(struct sock *sk) 12401da177e4SLinus Torvalds { 12411da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12421da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 1243c1b4a7e6SDavid S. Miller u32 mss_now; 124433ad798cSAdam Langley unsigned header_len; 124533ad798cSAdam Langley struct tcp_out_options opts; 124633ad798cSAdam Langley struct tcp_md5sig_key *md5; 12471da177e4SLinus Torvalds 1248c1b4a7e6SDavid S. Miller mss_now = tp->mss_cache; 1249c1b4a7e6SDavid S. Miller 12501da177e4SLinus Torvalds if (dst) { 12511da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 1252d83d8461SArnaldo Carvalho de Melo if (mtu != inet_csk(sk)->icsk_pmtu_cookie) 12531da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 12541da177e4SLinus Torvalds } 12551da177e4SLinus Torvalds 125633ad798cSAdam Langley header_len = tcp_established_options(sk, NULL, &opts, &md5) + 125733ad798cSAdam Langley sizeof(struct tcphdr); 125833ad798cSAdam Langley /* The mss_cache is sized based on tp->tcp_header_len, which assumes 125933ad798cSAdam Langley * some common options. If this is an odd packet (because we have SACK 126033ad798cSAdam Langley * blocks etc) then our calculated header_len will be different, and 126133ad798cSAdam Langley * we have to adjust mss_now correspondingly */ 126233ad798cSAdam Langley if (header_len != tp->tcp_header_len) { 126333ad798cSAdam Langley int delta = (int) header_len - tp->tcp_header_len; 126433ad798cSAdam Langley mss_now -= delta; 126533ad798cSAdam Langley } 1266cfb6eeb4SYOSHIFUJI Hideaki 12671da177e4SLinus Torvalds return mss_now; 12681da177e4SLinus Torvalds } 12691da177e4SLinus Torvalds 1270a762a980SDavid S. Miller /* Congestion window validation. (RFC2861) */ 12719e412ba7SIlpo Järvinen static void tcp_cwnd_validate(struct sock *sk) 1272a762a980SDavid S. Miller { 12739e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1274a762a980SDavid S. Miller 1275d436d686SIlpo Järvinen if (tp->packets_out >= tp->snd_cwnd) { 1276a762a980SDavid S. Miller /* Network is feed fully. */ 1277a762a980SDavid S. Miller tp->snd_cwnd_used = 0; 1278a762a980SDavid S. Miller tp->snd_cwnd_stamp = tcp_time_stamp; 1279a762a980SDavid S. Miller } else { 1280a762a980SDavid S. Miller /* Network starves. */ 1281a762a980SDavid S. Miller if (tp->packets_out > tp->snd_cwnd_used) 1282a762a980SDavid S. Miller tp->snd_cwnd_used = tp->packets_out; 1283a762a980SDavid S. Miller 128415d33c07SDavid S. Miller if (sysctl_tcp_slow_start_after_idle && 128515d33c07SDavid S. Miller (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) 1286a762a980SDavid S. Miller tcp_cwnd_application_limited(sk); 1287a762a980SDavid S. Miller } 1288a762a980SDavid S. Miller } 1289a762a980SDavid S. Miller 12900e3a4803SIlpo Järvinen /* Returns the portion of skb which can be sent right away without 12910e3a4803SIlpo Järvinen * introducing MSS oddities to segment boundaries. In rare cases where 12920e3a4803SIlpo Järvinen * mss_now != mss_cache, we will request caller to create a small skb 12930e3a4803SIlpo Järvinen * per input skb which could be mostly avoided here (if desired). 12945ea3a748SIlpo Järvinen * 12955ea3a748SIlpo Järvinen * We explicitly want to create a request for splitting write queue tail 12965ea3a748SIlpo Järvinen * to a small skb for Nagle purposes while avoiding unnecessary modulos, 12975ea3a748SIlpo Järvinen * thus all the complexity (cwnd_len is always MSS multiple which we 12985ea3a748SIlpo Järvinen * return whenever allowed by the other factors). Basically we need the 12995ea3a748SIlpo Järvinen * modulo only when the receiver window alone is the limiting factor or 13005ea3a748SIlpo Järvinen * when we would be allowed to send the split-due-to-Nagle skb fully. 13010e3a4803SIlpo Järvinen */ 13020e3a4803SIlpo Järvinen static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb, 1303056834d9SIlpo Järvinen unsigned int mss_now, unsigned int cwnd) 1304c1b4a7e6SDavid S. Miller { 13050e3a4803SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 13060e3a4803SIlpo Järvinen u32 needed, window, cwnd_len; 1307c1b4a7e6SDavid S. Miller 130890840defSIlpo Järvinen window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1309c1b4a7e6SDavid S. Miller cwnd_len = mss_now * cwnd; 13100e3a4803SIlpo Järvinen 13110e3a4803SIlpo Järvinen if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk))) 13120e3a4803SIlpo Järvinen return cwnd_len; 13130e3a4803SIlpo Järvinen 13145ea3a748SIlpo Järvinen needed = min(skb->len, window); 13155ea3a748SIlpo Järvinen 131617515408SIlpo Järvinen if (cwnd_len <= needed) 13170e3a4803SIlpo Järvinen return cwnd_len; 13180e3a4803SIlpo Järvinen 13190e3a4803SIlpo Järvinen return needed - needed % mss_now; 1320c1b4a7e6SDavid S. Miller } 1321c1b4a7e6SDavid S. Miller 1322c1b4a7e6SDavid S. Miller /* Can at least one segment of SKB be sent right now, according to the 1323c1b4a7e6SDavid S. Miller * congestion window rules? If so, return how many segments are allowed. 1324c1b4a7e6SDavid S. Miller */ 1325056834d9SIlpo Järvinen static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, 1326056834d9SIlpo Järvinen struct sk_buff *skb) 1327c1b4a7e6SDavid S. Miller { 1328c1b4a7e6SDavid S. Miller u32 in_flight, cwnd; 1329c1b4a7e6SDavid S. Miller 1330c1b4a7e6SDavid S. Miller /* Don't be strict about the congestion window for the final FIN. */ 1331a3433f35SChangli Gao if ((TCP_SKB_CB(skb)->flags & TCPHDR_FIN) && tcp_skb_pcount(skb) == 1) 1332c1b4a7e6SDavid S. Miller return 1; 1333c1b4a7e6SDavid S. Miller 1334c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1335c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1336c1b4a7e6SDavid S. Miller if (in_flight < cwnd) 1337c1b4a7e6SDavid S. Miller return (cwnd - in_flight); 1338c1b4a7e6SDavid S. Miller 1339c1b4a7e6SDavid S. Miller return 0; 1340c1b4a7e6SDavid S. Miller } 1341c1b4a7e6SDavid S. Miller 134267edfef7SAndi Kleen /* Intialize TSO state of a skb. 134367edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1344c1b4a7e6SDavid S. Miller * SKB onto the wire. 1345c1b4a7e6SDavid S. Miller */ 1346056834d9SIlpo Järvinen static int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, 1347056834d9SIlpo Järvinen unsigned int mss_now) 1348c1b4a7e6SDavid S. Miller { 1349c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1350c1b4a7e6SDavid S. Miller 1351f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 1352846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1353c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1354c1b4a7e6SDavid S. Miller } 1355c1b4a7e6SDavid S. Miller return tso_segs; 1356c1b4a7e6SDavid S. Miller } 1357c1b4a7e6SDavid S. Miller 135867edfef7SAndi Kleen /* Minshall's variant of the Nagle send check. */ 1359c1b4a7e6SDavid S. Miller static inline int tcp_minshall_check(const struct tcp_sock *tp) 1360c1b4a7e6SDavid S. Miller { 1361c1b4a7e6SDavid S. Miller return after(tp->snd_sml, tp->snd_una) && 1362c1b4a7e6SDavid S. Miller !after(tp->snd_sml, tp->snd_nxt); 1363c1b4a7e6SDavid S. Miller } 1364c1b4a7e6SDavid S. Miller 1365c1b4a7e6SDavid S. Miller /* Return 0, if packet can be sent now without violation Nagle's rules: 1366c1b4a7e6SDavid S. Miller * 1. It is full sized. 1367c1b4a7e6SDavid S. Miller * 2. Or it contains FIN. (already checked by caller) 1368c1b4a7e6SDavid S. Miller * 3. Or TCP_NODELAY was set. 1369c1b4a7e6SDavid S. Miller * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1370c1b4a7e6SDavid S. Miller * With Minshall's modification: all sent small packets are ACKed. 1371c1b4a7e6SDavid S. Miller */ 1372c1b4a7e6SDavid S. Miller static inline int tcp_nagle_check(const struct tcp_sock *tp, 1373c1b4a7e6SDavid S. Miller const struct sk_buff *skb, 1374c1b4a7e6SDavid S. Miller unsigned mss_now, int nonagle) 1375c1b4a7e6SDavid S. Miller { 1376c1b4a7e6SDavid S. Miller return (skb->len < mss_now && 1377c1b4a7e6SDavid S. Miller ((nonagle & TCP_NAGLE_CORK) || 1378056834d9SIlpo Järvinen (!nonagle && tp->packets_out && tcp_minshall_check(tp)))); 1379c1b4a7e6SDavid S. Miller } 1380c1b4a7e6SDavid S. Miller 1381c1b4a7e6SDavid S. Miller /* Return non-zero if the Nagle test allows this packet to be 1382c1b4a7e6SDavid S. Miller * sent now. 1383c1b4a7e6SDavid S. Miller */ 1384c1b4a7e6SDavid S. Miller static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, 1385c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1386c1b4a7e6SDavid S. Miller { 1387c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1388c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1389c1b4a7e6SDavid S. Miller * 1390c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1391c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1392c1b4a7e6SDavid S. Miller */ 1393c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1394c1b4a7e6SDavid S. Miller return 1; 1395c1b4a7e6SDavid S. Miller 1396d551e454SIlpo Järvinen /* Don't use the nagle rule for urgent data (or for the final FIN). 1397d551e454SIlpo Järvinen * Nagle can be ignored during F-RTO too (see RFC4138). 1398d551e454SIlpo Järvinen */ 139933f5f57eSIlpo Järvinen if (tcp_urg_mode(tp) || (tp->frto_counter == 2) || 1400a3433f35SChangli Gao (TCP_SKB_CB(skb)->flags & TCPHDR_FIN)) 1401c1b4a7e6SDavid S. Miller return 1; 1402c1b4a7e6SDavid S. Miller 1403c1b4a7e6SDavid S. Miller if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) 1404c1b4a7e6SDavid S. Miller return 1; 1405c1b4a7e6SDavid S. Miller 1406c1b4a7e6SDavid S. Miller return 0; 1407c1b4a7e6SDavid S. Miller } 1408c1b4a7e6SDavid S. Miller 1409c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1410056834d9SIlpo Järvinen static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, 1411056834d9SIlpo Järvinen unsigned int cur_mss) 1412c1b4a7e6SDavid S. Miller { 1413c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1414c1b4a7e6SDavid S. Miller 1415c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1416c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1417c1b4a7e6SDavid S. Miller 141890840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1419c1b4a7e6SDavid S. Miller } 1420c1b4a7e6SDavid S. Miller 1421fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1422c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1423c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1424c1b4a7e6SDavid S. Miller */ 1425c1b4a7e6SDavid S. Miller static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, 1426c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1427c1b4a7e6SDavid S. Miller { 1428c1b4a7e6SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1429c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1430c1b4a7e6SDavid S. Miller 1431846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 1432c1b4a7e6SDavid S. Miller 1433c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1434c1b4a7e6SDavid S. Miller return 0; 1435c1b4a7e6SDavid S. Miller 1436c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1437056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1438c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1439c1b4a7e6SDavid S. Miller 1440c1b4a7e6SDavid S. Miller return cwnd_quota; 1441c1b4a7e6SDavid S. Miller } 1442c1b4a7e6SDavid S. Miller 144367edfef7SAndi Kleen /* Test if sending is allowed right now. */ 14449e412ba7SIlpo Järvinen int tcp_may_send_now(struct sock *sk) 1445c1b4a7e6SDavid S. Miller { 14469e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1447fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1448c1b4a7e6SDavid S. Miller 1449c1b4a7e6SDavid S. Miller return (skb && 14500c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1451c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 14524e67d876SIlpo Järvinen tp->nonagle : TCP_NAGLE_PUSH))); 1453c1b4a7e6SDavid S. Miller } 1454c1b4a7e6SDavid S. Miller 1455c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1456c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1457c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1458c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1459c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1460c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1461c1b4a7e6SDavid S. Miller */ 1462056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1463*c4ead4c5SEric Dumazet unsigned int mss_now, gfp_t gfp) 1464c1b4a7e6SDavid S. Miller { 1465c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1466c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 14679ce01461SIlpo Järvinen u8 flags; 1468c1b4a7e6SDavid S. Miller 1469c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1470c8ac3774SHerbert Xu if (skb->len != skb->data_len) 1471c8ac3774SHerbert Xu return tcp_fragment(sk, skb, len, mss_now); 1472c1b4a7e6SDavid S. Miller 1473*c4ead4c5SEric Dumazet buff = sk_stream_alloc_skb(sk, 0, gfp); 1474c1b4a7e6SDavid S. Miller if (unlikely(buff == NULL)) 1475c1b4a7e6SDavid S. Miller return -ENOMEM; 1476c1b4a7e6SDavid S. Miller 14773ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 14783ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1479b60b49eaSHerbert Xu buff->truesize += nlen; 1480c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1481c1b4a7e6SDavid S. Miller 1482c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1483c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1484c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1485c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1486c1b4a7e6SDavid S. Miller 1487c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 1488c1b4a7e6SDavid S. Miller flags = TCP_SKB_CB(skb)->flags; 1489a3433f35SChangli Gao TCP_SKB_CB(skb)->flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); 1490c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->flags = flags; 1491c1b4a7e6SDavid S. Miller 1492c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1493c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1494c1b4a7e6SDavid S. Miller 149584fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1496c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1497c1b4a7e6SDavid S. Miller 1498c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 1499846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1500846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 1501c1b4a7e6SDavid S. Miller 1502c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1503c1b4a7e6SDavid S. Miller skb_header_release(buff); 1504fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1505c1b4a7e6SDavid S. Miller 1506c1b4a7e6SDavid S. Miller return 0; 1507c1b4a7e6SDavid S. Miller } 1508c1b4a7e6SDavid S. Miller 1509c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1510c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1511c1b4a7e6SDavid S. Miller * 1512c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1513c1b4a7e6SDavid S. Miller */ 15149e412ba7SIlpo Järvinen static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) 1515c1b4a7e6SDavid S. Miller { 15169e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 15176687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1518c1b4a7e6SDavid S. Miller u32 send_win, cong_win, limit, in_flight; 1519c1b4a7e6SDavid S. Miller 1520a3433f35SChangli Gao if (TCP_SKB_CB(skb)->flags & TCPHDR_FIN) 1521ae8064acSJohn Heffner goto send_now; 1522c1b4a7e6SDavid S. Miller 15236687e988SArnaldo Carvalho de Melo if (icsk->icsk_ca_state != TCP_CA_Open) 1524ae8064acSJohn Heffner goto send_now; 1525ae8064acSJohn Heffner 1526ae8064acSJohn Heffner /* Defer for less than two clock ticks. */ 1527bd515c3eSIlpo Järvinen if (tp->tso_deferred && 1528a2acde07SIlpo Järvinen (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) 1529ae8064acSJohn Heffner goto send_now; 1530908a75c1SDavid S. Miller 1531c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1532c1b4a7e6SDavid S. Miller 1533056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1534c1b4a7e6SDavid S. Miller 153590840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1536c1b4a7e6SDavid S. Miller 1537c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1538c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1539c1b4a7e6SDavid S. Miller 1540c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1541c1b4a7e6SDavid S. Miller 1542ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 154382cc1a7aSPeter P Waskiewicz Jr if (limit >= sk->sk_gso_max_size) 1544ae8064acSJohn Heffner goto send_now; 1545ba244fe9SDavid S. Miller 154662ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 154762ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 154862ad2761SIlpo Järvinen goto send_now; 154962ad2761SIlpo Järvinen 1550c1b4a7e6SDavid S. Miller if (sysctl_tcp_tso_win_divisor) { 1551c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1552c1b4a7e6SDavid S. Miller 1553c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1554c1b4a7e6SDavid S. Miller * just use it. 1555c1b4a7e6SDavid S. Miller */ 1556c1b4a7e6SDavid S. Miller chunk /= sysctl_tcp_tso_win_divisor; 1557c1b4a7e6SDavid S. Miller if (limit >= chunk) 1558ae8064acSJohn Heffner goto send_now; 1559c1b4a7e6SDavid S. Miller } else { 1560c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1561c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1562c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1563c1b4a7e6SDavid S. Miller * then send now. 1564c1b4a7e6SDavid S. Miller */ 1565c1b4a7e6SDavid S. Miller if (limit > tcp_max_burst(tp) * tp->mss_cache) 1566ae8064acSJohn Heffner goto send_now; 1567c1b4a7e6SDavid S. Miller } 1568c1b4a7e6SDavid S. Miller 1569c1b4a7e6SDavid S. Miller /* Ok, it looks like it is advisable to defer. */ 1570ae8064acSJohn Heffner tp->tso_deferred = 1 | (jiffies << 1); 1571ae8064acSJohn Heffner 1572c1b4a7e6SDavid S. Miller return 1; 1573ae8064acSJohn Heffner 1574ae8064acSJohn Heffner send_now: 1575ae8064acSJohn Heffner tp->tso_deferred = 0; 1576ae8064acSJohn Heffner return 0; 1577c1b4a7e6SDavid S. Miller } 1578c1b4a7e6SDavid S. Miller 15795d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 158067edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 158167edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 158267edfef7SAndi Kleen * changes resulting in larger path MTUs. 158367edfef7SAndi Kleen * 15845d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 15855d424d5aSJohn Heffner * 1 if a probe was sent, 1586056834d9SIlpo Järvinen * -1 otherwise 1587056834d9SIlpo Järvinen */ 15885d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 15895d424d5aSJohn Heffner { 15905d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 15915d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 15925d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 15935d424d5aSJohn Heffner int len; 15945d424d5aSJohn Heffner int probe_size; 159591cc17c0SIlpo Järvinen int size_needed; 15965d424d5aSJohn Heffner int copy; 15975d424d5aSJohn Heffner int mss_now; 15985d424d5aSJohn Heffner 15995d424d5aSJohn Heffner /* Not currently probing/verifying, 16005d424d5aSJohn Heffner * not in recovery, 16015d424d5aSJohn Heffner * have enough cwnd, and 16025d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 16035d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 16045d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 16055d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 16065d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1607cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 16085d424d5aSJohn Heffner return -1; 16095d424d5aSJohn Heffner 16105d424d5aSJohn Heffner /* Very simple search strategy: just double the MSS. */ 16110c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 16125d424d5aSJohn Heffner probe_size = 2 * tp->mss_cache; 161391cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 16145d424d5aSJohn Heffner if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { 16155d424d5aSJohn Heffner /* TODO: set timer for probe_converge_event */ 16165d424d5aSJohn Heffner return -1; 16175d424d5aSJohn Heffner } 16185d424d5aSJohn Heffner 16195d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 16207f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 16215d424d5aSJohn Heffner return -1; 16225d424d5aSJohn Heffner 162391cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 16245d424d5aSJohn Heffner return -1; 162590840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 16265d424d5aSJohn Heffner return 0; 16275d424d5aSJohn Heffner 1628d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1629d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1630d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 16315d424d5aSJohn Heffner return -1; 16325d424d5aSJohn Heffner else 16335d424d5aSJohn Heffner return 0; 16345d424d5aSJohn Heffner } 16355d424d5aSJohn Heffner 16365d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 16375d424d5aSJohn Heffner if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) 16385d424d5aSJohn Heffner return -1; 16393ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 16403ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 16415d424d5aSJohn Heffner 1642fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 16435d424d5aSJohn Heffner 16445d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 16455d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 1646a3433f35SChangli Gao TCP_SKB_CB(nskb)->flags = TCPHDR_ACK; 16475d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 16485d424d5aSJohn Heffner nskb->csum = 0; 164984fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 16505d424d5aSJohn Heffner 165150c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 165250c4817eSIlpo Järvinen 16535d424d5aSJohn Heffner len = 0; 1654234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 16555d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 16565d424d5aSJohn Heffner if (nskb->ip_summed) 16575d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 16585d424d5aSJohn Heffner else 16595d424d5aSJohn Heffner nskb->csum = skb_copy_and_csum_bits(skb, 0, 1660056834d9SIlpo Järvinen skb_put(nskb, copy), 1661056834d9SIlpo Järvinen copy, nskb->csum); 16625d424d5aSJohn Heffner 16635d424d5aSJohn Heffner if (skb->len <= copy) { 16645d424d5aSJohn Heffner /* We've eaten all the data from this skb. 16655d424d5aSJohn Heffner * Throw it away. */ 16665d424d5aSJohn Heffner TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags; 1667fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 16683ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 16695d424d5aSJohn Heffner } else { 16705d424d5aSJohn Heffner TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags & 1671a3433f35SChangli Gao ~(TCPHDR_FIN|TCPHDR_PSH); 16725d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 16735d424d5aSJohn Heffner skb_pull(skb, copy); 167484fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 1675056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 1676056834d9SIlpo Järvinen skb->len, 0); 16775d424d5aSJohn Heffner } else { 16785d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 16795d424d5aSJohn Heffner tcp_set_skb_tso_segs(sk, skb, mss_now); 16805d424d5aSJohn Heffner } 16815d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 16825d424d5aSJohn Heffner } 16835d424d5aSJohn Heffner 16845d424d5aSJohn Heffner len += copy; 1685234b6860SIlpo Järvinen 1686234b6860SIlpo Järvinen if (len >= probe_size) 1687234b6860SIlpo Järvinen break; 16885d424d5aSJohn Heffner } 16895d424d5aSJohn Heffner tcp_init_tso_segs(sk, nskb, nskb->len); 16905d424d5aSJohn Heffner 16915d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 16925d424d5aSJohn Heffner * be resegmented into mss-sized pieces by tcp_write_xmit(). */ 16935d424d5aSJohn Heffner TCP_SKB_CB(nskb)->when = tcp_time_stamp; 16945d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 16955d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 16965d424d5aSJohn Heffner * effectively two packets. */ 16975d424d5aSJohn Heffner tp->snd_cwnd--; 169866f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 16995d424d5aSJohn Heffner 17005d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 17010e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 17020e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 17035d424d5aSJohn Heffner 17045d424d5aSJohn Heffner return 1; 17055d424d5aSJohn Heffner } 17065d424d5aSJohn Heffner 17075d424d5aSJohn Heffner return -1; 17085d424d5aSJohn Heffner } 17095d424d5aSJohn Heffner 17101da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 17111da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 17121da177e4SLinus Torvalds * window for us. 17131da177e4SLinus Torvalds * 1714f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 1715f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 1716f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 1717f8269a49SIlpo Järvinen * 17181da177e4SLinus Torvalds * Returns 1, if no segments are in flight and we have queued segments, but 17191da177e4SLinus Torvalds * cannot send anything now because of SWS or another problem. 17201da177e4SLinus Torvalds */ 1721d5dd9175SIlpo Järvinen static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 1722d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 17231da177e4SLinus Torvalds { 17241da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 172592df7b51SDavid S. Miller struct sk_buff *skb; 1726c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 1727c1b4a7e6SDavid S. Miller int cwnd_quota; 17285d424d5aSJohn Heffner int result; 17291da177e4SLinus Torvalds 1730c1b4a7e6SDavid S. Miller sent_pkts = 0; 17315d424d5aSJohn Heffner 1732d5dd9175SIlpo Järvinen if (!push_one) { 17335d424d5aSJohn Heffner /* Do MTU probing. */ 1734d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 1735d5dd9175SIlpo Järvinen if (!result) { 17365d424d5aSJohn Heffner return 0; 17375d424d5aSJohn Heffner } else if (result > 0) { 17385d424d5aSJohn Heffner sent_pkts = 1; 17395d424d5aSJohn Heffner } 1740d5dd9175SIlpo Järvinen } 17415d424d5aSJohn Heffner 1742fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 1743c8ac3774SHerbert Xu unsigned int limit; 1744c8ac3774SHerbert Xu 1745b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 1746c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 1747c1b4a7e6SDavid S. Miller 1748b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 1749b68e9f85SHerbert Xu if (!cwnd_quota) 1750b68e9f85SHerbert Xu break; 1751b68e9f85SHerbert Xu 1752b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 1753b68e9f85SHerbert Xu break; 1754b68e9f85SHerbert Xu 1755c1b4a7e6SDavid S. Miller if (tso_segs == 1) { 1756aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 1757aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1758aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 1759aa93466bSDavid S. Miller break; 1760c1b4a7e6SDavid S. Miller } else { 1761d5dd9175SIlpo Järvinen if (!push_one && tcp_tso_should_defer(sk, skb)) 1762aa93466bSDavid S. Miller break; 1763c1b4a7e6SDavid S. Miller } 1764aa93466bSDavid S. Miller 1765c8ac3774SHerbert Xu limit = mss_now; 1766f8269a49SIlpo Järvinen if (tso_segs > 1 && !tcp_urg_mode(tp)) 17670e3a4803SIlpo Järvinen limit = tcp_mss_split_point(sk, skb, mss_now, 17680e3a4803SIlpo Järvinen cwnd_quota); 1769c8ac3774SHerbert Xu 1770c8ac3774SHerbert Xu if (skb->len > limit && 1771*c4ead4c5SEric Dumazet unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) 17721da177e4SLinus Torvalds break; 17731da177e4SLinus Torvalds 17741da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 1775c1b4a7e6SDavid S. Miller 1776d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 17771da177e4SLinus Torvalds break; 17781da177e4SLinus Torvalds 17791da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 17801da177e4SLinus Torvalds * This call will increment packets_out. 17811da177e4SLinus Torvalds */ 178266f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 17831da177e4SLinus Torvalds 17841da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 1785aa93466bSDavid S. Miller sent_pkts++; 1786d5dd9175SIlpo Järvinen 1787d5dd9175SIlpo Järvinen if (push_one) 1788d5dd9175SIlpo Järvinen break; 17891da177e4SLinus Torvalds } 17901da177e4SLinus Torvalds 1791aa93466bSDavid S. Miller if (likely(sent_pkts)) { 17929e412ba7SIlpo Järvinen tcp_cwnd_validate(sk); 17931da177e4SLinus Torvalds return 0; 17941da177e4SLinus Torvalds } 1795fe067e8aSDavid S. Miller return !tp->packets_out && tcp_send_head(sk); 17961da177e4SLinus Torvalds } 17971da177e4SLinus Torvalds 1798a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 1799a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 1800a762a980SDavid S. Miller * The socket must be locked by the caller. 1801a762a980SDavid S. Miller */ 18029e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 18039e412ba7SIlpo Järvinen int nonagle) 1804a762a980SDavid S. Miller { 1805726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 1806726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 1807726e07a8SIlpo Järvinen * all will be happy. 1808726e07a8SIlpo Järvinen */ 1809726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 1810726e07a8SIlpo Järvinen return; 1811726e07a8SIlpo Järvinen 1812d5dd9175SIlpo Järvinen if (tcp_write_xmit(sk, cur_mss, nonagle, 0, GFP_ATOMIC)) 18139e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 1814a762a980SDavid S. Miller } 1815a762a980SDavid S. Miller 1816c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 1817c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 1818c1b4a7e6SDavid S. Miller */ 1819c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 1820c1b4a7e6SDavid S. Miller { 1821fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1822c1b4a7e6SDavid S. Miller 1823c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 1824c1b4a7e6SDavid S. Miller 1825d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 1826c1b4a7e6SDavid S. Miller } 1827c1b4a7e6SDavid S. Miller 18281da177e4SLinus Torvalds /* This function returns the amount that we can raise the 18291da177e4SLinus Torvalds * usable window based on the following constraints 18301da177e4SLinus Torvalds * 18311da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 18321da177e4SLinus Torvalds * 2. We limit memory per socket 18331da177e4SLinus Torvalds * 18341da177e4SLinus Torvalds * RFC 1122: 18351da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 18361da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 18371da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 18381da177e4SLinus Torvalds * 18391da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 18401da177e4SLinus Torvalds * it at least MSS bytes. 18411da177e4SLinus Torvalds * 18421da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 18431da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 18441da177e4SLinus Torvalds * 18451da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 18461da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 18471da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 18481da177e4SLinus Torvalds * window to always advance by a single byte. 18491da177e4SLinus Torvalds * 18501da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 18511da177e4SLinus Torvalds * then this will not be a problem. 18521da177e4SLinus Torvalds * 18531da177e4SLinus Torvalds * BSD seems to make the following compromise: 18541da177e4SLinus Torvalds * 18551da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 18561da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 18571da177e4SLinus Torvalds * then set the window to 0. 18581da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 18591da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 18601da177e4SLinus Torvalds * and from being larger than the largest representable value. 18611da177e4SLinus Torvalds * 18621da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 18631da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 18641da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 18651da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 18661da177e4SLinus Torvalds * because the pipeline is full. 18671da177e4SLinus Torvalds * 18681da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 18691da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 18701da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 18711da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 18721da177e4SLinus Torvalds * of having a fixed window size at almost all times. 18731da177e4SLinus Torvalds * 18741da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 18751da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 18761da177e4SLinus Torvalds * 18771da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 18781da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 18791da177e4SLinus Torvalds */ 18801da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 18811da177e4SLinus Torvalds { 1882463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 18831da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1884caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 18851da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 18861da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 18871da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 18881da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 18891da177e4SLinus Torvalds */ 1890463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 18911da177e4SLinus Torvalds int free_space = tcp_space(sk); 18921da177e4SLinus Torvalds int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); 18931da177e4SLinus Torvalds int window; 18941da177e4SLinus Torvalds 18951da177e4SLinus Torvalds if (mss > full_space) 18961da177e4SLinus Torvalds mss = full_space; 18971da177e4SLinus Torvalds 1898b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 1899463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 19001da177e4SLinus Torvalds 19011da177e4SLinus Torvalds if (tcp_memory_pressure) 1902056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 1903056834d9SIlpo Järvinen 4U * tp->advmss); 19041da177e4SLinus Torvalds 19051da177e4SLinus Torvalds if (free_space < mss) 19061da177e4SLinus Torvalds return 0; 19071da177e4SLinus Torvalds } 19081da177e4SLinus Torvalds 19091da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 19101da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 19111da177e4SLinus Torvalds 19121da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 19131da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 19141da177e4SLinus Torvalds */ 19151da177e4SLinus Torvalds window = tp->rcv_wnd; 19161da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 19171da177e4SLinus Torvalds window = free_space; 19181da177e4SLinus Torvalds 19191da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 19201da177e4SLinus Torvalds * Import case: prevent zero window announcement if 19211da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 19221da177e4SLinus Torvalds */ 19231da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 19241da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 19251da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 19261da177e4SLinus Torvalds } else { 19271da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 19281da177e4SLinus Torvalds * Window clamp already applied above. 19291da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 19301da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 19311da177e4SLinus Torvalds * and multiply from happening most of the time. 19321da177e4SLinus Torvalds * We also don't do any window rounding when the free space 19331da177e4SLinus Torvalds * is too small. 19341da177e4SLinus Torvalds */ 19351da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 19361da177e4SLinus Torvalds window = (free_space / mss) * mss; 193784565070SJohn Heffner else if (mss == full_space && 1938b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 193984565070SJohn Heffner window = free_space; 19401da177e4SLinus Torvalds } 19411da177e4SLinus Torvalds 19421da177e4SLinus Torvalds return window; 19431da177e4SLinus Torvalds } 19441da177e4SLinus Torvalds 19454a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 19464a17fc3aSIlpo Järvinen static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 19471da177e4SLinus Torvalds { 19481da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1949fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 1950058dc334SIlpo Järvinen int skb_size, next_skb_size; 19511da177e4SLinus Torvalds 1952058dc334SIlpo Järvinen skb_size = skb->len; 1953058dc334SIlpo Järvinen next_skb_size = next_skb->len; 19541da177e4SLinus Torvalds 1955058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 19561da177e4SLinus Torvalds 19576859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 1958a6963a6bSIlpo Järvinen 1959fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 19601da177e4SLinus Torvalds 1961058dc334SIlpo Järvinen skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), 19621a4e2d09SArnaldo Carvalho de Melo next_skb_size); 19631da177e4SLinus Torvalds 196452d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 196552d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 19661da177e4SLinus Torvalds 196784fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 19681da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 19691da177e4SLinus Torvalds 19701da177e4SLinus Torvalds /* Update sequence range on original skb. */ 19711da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 19721da177e4SLinus Torvalds 1973e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 1974e6c7d085SIlpo Järvinen TCP_SKB_CB(skb)->flags |= TCP_SKB_CB(next_skb)->flags; 19751da177e4SLinus Torvalds 19761da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 19771da177e4SLinus Torvalds * packet counting does not break. 19781da177e4SLinus Torvalds */ 19794828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 1980b7689205SIlpo Järvinen 1981b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 1982ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 1983ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 1984ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 1985b7689205SIlpo Järvinen 1986797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 1987797108d1SIlpo Järvinen 19883ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 19891da177e4SLinus Torvalds } 19901da177e4SLinus Torvalds 199167edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 19924a17fc3aSIlpo Järvinen static int tcp_can_collapse(struct sock *sk, struct sk_buff *skb) 19934a17fc3aSIlpo Järvinen { 19944a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 19954a17fc3aSIlpo Järvinen return 0; 19964a17fc3aSIlpo Järvinen /* TODO: SACK collapsing could be used to remove this condition */ 19974a17fc3aSIlpo Järvinen if (skb_shinfo(skb)->nr_frags != 0) 19984a17fc3aSIlpo Järvinen return 0; 19994a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 20004a17fc3aSIlpo Järvinen return 0; 20014a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 20024a17fc3aSIlpo Järvinen return 0; 20034a17fc3aSIlpo Järvinen /* Some heurestics for collapsing over SACK'd could be invented */ 20044a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 20054a17fc3aSIlpo Järvinen return 0; 20064a17fc3aSIlpo Järvinen 20074a17fc3aSIlpo Järvinen return 1; 20084a17fc3aSIlpo Järvinen } 20094a17fc3aSIlpo Järvinen 201067edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 201167edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 201267edfef7SAndi Kleen */ 20134a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 20144a17fc3aSIlpo Järvinen int space) 20154a17fc3aSIlpo Järvinen { 20164a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 20174a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 20184a17fc3aSIlpo Järvinen int first = 1; 20194a17fc3aSIlpo Järvinen 20204a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 20214a17fc3aSIlpo Järvinen return; 2022a3433f35SChangli Gao if (TCP_SKB_CB(skb)->flags & TCPHDR_SYN) 20234a17fc3aSIlpo Järvinen return; 20244a17fc3aSIlpo Järvinen 20254a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 20264a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 20274a17fc3aSIlpo Järvinen break; 20284a17fc3aSIlpo Järvinen 20294a17fc3aSIlpo Järvinen space -= skb->len; 20304a17fc3aSIlpo Järvinen 20314a17fc3aSIlpo Järvinen if (first) { 20324a17fc3aSIlpo Järvinen first = 0; 20334a17fc3aSIlpo Järvinen continue; 20344a17fc3aSIlpo Järvinen } 20354a17fc3aSIlpo Järvinen 20364a17fc3aSIlpo Järvinen if (space < 0) 20374a17fc3aSIlpo Järvinen break; 20384a17fc3aSIlpo Järvinen /* Punt if not enough space exists in the first SKB for 20394a17fc3aSIlpo Järvinen * the data in the second 20404a17fc3aSIlpo Järvinen */ 20414a17fc3aSIlpo Järvinen if (skb->len > skb_tailroom(to)) 20424a17fc3aSIlpo Järvinen break; 20434a17fc3aSIlpo Järvinen 20444a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 20454a17fc3aSIlpo Järvinen break; 20464a17fc3aSIlpo Järvinen 20474a17fc3aSIlpo Järvinen tcp_collapse_retrans(sk, to); 20484a17fc3aSIlpo Järvinen } 20494a17fc3aSIlpo Järvinen } 20504a17fc3aSIlpo Järvinen 20511da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 20521da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 20531da177e4SLinus Torvalds * error occurred which prevented the send. 20541da177e4SLinus Torvalds */ 20551da177e4SLinus Torvalds int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 20561da177e4SLinus Torvalds { 20571da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 20585d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 20597d227cd2SSridhar Samudrala unsigned int cur_mss; 20601da177e4SLinus Torvalds int err; 20611da177e4SLinus Torvalds 20625d424d5aSJohn Heffner /* Inconslusive MTU probe */ 20635d424d5aSJohn Heffner if (icsk->icsk_mtup.probe_size) { 20645d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 20655d424d5aSJohn Heffner } 20665d424d5aSJohn Heffner 20671da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2068caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 20691da177e4SLinus Torvalds */ 20701da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 20711da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 20721da177e4SLinus Torvalds return -EAGAIN; 20731da177e4SLinus Torvalds 20741da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 20751da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 20761da177e4SLinus Torvalds BUG(); 20771da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 20781da177e4SLinus Torvalds return -ENOMEM; 20791da177e4SLinus Torvalds } 20801da177e4SLinus Torvalds 20817d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 20827d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 20837d227cd2SSridhar Samudrala 20840c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 20857d227cd2SSridhar Samudrala 20861da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 20871da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 20881da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 20891da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 20901da177e4SLinus Torvalds */ 20919d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 20929d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 20931da177e4SLinus Torvalds return -EAGAIN; 20941da177e4SLinus Torvalds 20951da177e4SLinus Torvalds if (skb->len > cur_mss) { 2096846998aeSDavid S. Miller if (tcp_fragment(sk, skb, cur_mss, cur_mss)) 20971da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 209802276f3cSIlpo Järvinen } else { 20999eb9362eSIlpo Järvinen int oldpcount = tcp_skb_pcount(skb); 21009eb9362eSIlpo Järvinen 21019eb9362eSIlpo Järvinen if (unlikely(oldpcount > 1)) { 210202276f3cSIlpo Järvinen tcp_init_tso_segs(sk, skb, cur_mss); 21039eb9362eSIlpo Järvinen tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); 21049eb9362eSIlpo Järvinen } 21051da177e4SLinus Torvalds } 21061da177e4SLinus Torvalds 21071da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 21081da177e4SLinus Torvalds 21091da177e4SLinus Torvalds /* Some Solaris stacks overoptimize and ignore the FIN on a 21101da177e4SLinus Torvalds * retransmit when old data is attached. So strip it off 21111da177e4SLinus Torvalds * since it is cheap to do so and saves bytes on the network. 21121da177e4SLinus Torvalds */ 21131da177e4SLinus Torvalds if (skb->len > 0 && 2114a3433f35SChangli Gao (TCP_SKB_CB(skb)->flags & TCPHDR_FIN) && 21151da177e4SLinus Torvalds tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { 21161da177e4SLinus Torvalds if (!pskb_trim(skb, 0)) { 2117e870a8efSIlpo Järvinen /* Reuse, even though it does some unnecessary work */ 2118e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1, 2119e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->flags); 21201da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 21211da177e4SLinus Torvalds } 21221da177e4SLinus Torvalds } 21231da177e4SLinus Torvalds 21241da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 21251da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 21261da177e4SLinus Torvalds */ 21271da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 21281da177e4SLinus Torvalds 2129dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 21301da177e4SLinus Torvalds 21311da177e4SLinus Torvalds if (err == 0) { 21321da177e4SLinus Torvalds /* Update global TCP statistics. */ 213381cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 21341da177e4SLinus Torvalds 21351da177e4SLinus Torvalds tp->total_retrans++; 21361da177e4SLinus Torvalds 21371da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 21381da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 21391da177e4SLinus Torvalds if (net_ratelimit()) 21401da177e4SLinus Torvalds printk(KERN_DEBUG "retrans_out leaked.\n"); 21411da177e4SLinus Torvalds } 21421da177e4SLinus Torvalds #endif 2143b08d6cb2SIlpo Järvinen if (!tp->retrans_out) 2144b08d6cb2SIlpo Järvinen tp->lost_retrans_low = tp->snd_nxt; 21451da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 21461da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 21471da177e4SLinus Torvalds 21481da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 21491da177e4SLinus Torvalds if (!tp->retrans_stamp) 21501da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(skb)->when; 21511da177e4SLinus Torvalds 21521da177e4SLinus Torvalds tp->undo_retrans++; 21531da177e4SLinus Torvalds 21541da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 21551da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 21561da177e4SLinus Torvalds */ 21571da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 21581da177e4SLinus Torvalds } 21591da177e4SLinus Torvalds return err; 21601da177e4SLinus Torvalds } 21611da177e4SLinus Torvalds 216267edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 216367edfef7SAndi Kleen * window/congestion state. 216467edfef7SAndi Kleen */ 2165b5afe7bcSIlpo Järvinen static int tcp_can_forward_retransmit(struct sock *sk) 2166b5afe7bcSIlpo Järvinen { 2167b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2168b5afe7bcSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 2169b5afe7bcSIlpo Järvinen 2170b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2171b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2172b5afe7bcSIlpo Järvinen return 0; 2173b5afe7bcSIlpo Järvinen 2174b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2175b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2176b5afe7bcSIlpo Järvinen return 0; 2177b5afe7bcSIlpo Järvinen 2178b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2179b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2180b5afe7bcSIlpo Järvinen * 2181b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2182b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2183b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2184b5afe7bcSIlpo Järvinen */ 2185b5afe7bcSIlpo Järvinen 2186b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2187b5afe7bcSIlpo Järvinen return 0; 2188b5afe7bcSIlpo Järvinen 2189b5afe7bcSIlpo Järvinen return 1; 2190b5afe7bcSIlpo Järvinen } 2191b5afe7bcSIlpo Järvinen 21921da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 21931da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 21941da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 21951da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 21961da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 21971da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 21981da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 21991da177e4SLinus Torvalds */ 22001da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 22011da177e4SLinus Torvalds { 22026687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 22031da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 22041da177e4SLinus Torvalds struct sk_buff *skb; 22050e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2206618d9f25SIlpo Järvinen u32 last_lost; 220761eb55f4SIlpo Järvinen int mib_idx; 22080e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 22096a438bbeSStephen Hemminger 221008ebd172SIlpo Järvinen if (!tp->lost_out) 221108ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 221208ebd172SIlpo Järvinen 2213618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 22146a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2215618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2216618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2217618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2218618d9f25SIlpo Järvinen } else { 2219fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2220618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2221618d9f25SIlpo Järvinen } 22221da177e4SLinus Torvalds 2223fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 22241da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 22251da177e4SLinus Torvalds 2226fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2227fe067e8aSDavid S. Miller break; 22286a438bbeSStephen Hemminger /* we could do better than to assign each time */ 22290e1c54c2SIlpo Järvinen if (hole == NULL) 22306a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 22316a438bbeSStephen Hemminger 22321da177e4SLinus Torvalds /* Assume this retransmit will generate 22331da177e4SLinus Torvalds * only one packet for congestion window 22341da177e4SLinus Torvalds * calculation purposes. This works because 22351da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 22361da177e4SLinus Torvalds * packet to be MSS sized and all the 22371da177e4SLinus Torvalds * packet counting works out. 22381da177e4SLinus Torvalds */ 22391da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 22401da177e4SLinus Torvalds return; 22410e1c54c2SIlpo Järvinen 22420e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 22430e1c54c2SIlpo Järvinen begin_fwd: 22440e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2245006f582cSIlpo Järvinen break; 22460e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 22470e1c54c2SIlpo Järvinen 22480e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2249618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 22500e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 22510e1c54c2SIlpo Järvinen break; 22520e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 22530e1c54c2SIlpo Järvinen if (hole != NULL) { 22540e1c54c2SIlpo Järvinen skb = hole; 22550e1c54c2SIlpo Järvinen hole = NULL; 22560e1c54c2SIlpo Järvinen } 22570e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 22580e1c54c2SIlpo Järvinen goto begin_fwd; 22590e1c54c2SIlpo Järvinen 22600e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 2261ac11ba75SIlpo Järvinen if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 22620e1c54c2SIlpo Järvinen hole = skb; 226361eb55f4SIlpo Järvinen continue; 22641da177e4SLinus Torvalds 22650e1c54c2SIlpo Järvinen } else { 2266618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 22670e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 22680e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 22690e1c54c2SIlpo Järvinen else 22700e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 22710e1c54c2SIlpo Järvinen } 22720e1c54c2SIlpo Järvinen 22730e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 227461eb55f4SIlpo Järvinen continue; 227540b215e5SPavel Emelyanov 2276f0ceb0edSIlpo Järvinen if (tcp_retransmit_skb(sk, skb)) 22771da177e4SLinus Torvalds return; 2278de0744afSPavel Emelyanov NET_INC_STATS_BH(sock_net(sk), mib_idx); 22791da177e4SLinus Torvalds 2280fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2281463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 22823f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 22833f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 22841da177e4SLinus Torvalds } 22851da177e4SLinus Torvalds } 22861da177e4SLinus Torvalds 22871da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 22881da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 22891da177e4SLinus Torvalds */ 22901da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 22911da177e4SLinus Torvalds { 22921da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2293fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_write_queue_tail(sk); 22941da177e4SLinus Torvalds int mss_now; 22951da177e4SLinus Torvalds 22961da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 22971da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 22981da177e4SLinus Torvalds * and IP options. 22991da177e4SLinus Torvalds */ 23000c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 23011da177e4SLinus Torvalds 2302fe067e8aSDavid S. Miller if (tcp_send_head(sk) != NULL) { 2303a3433f35SChangli Gao TCP_SKB_CB(skb)->flags |= TCPHDR_FIN; 23041da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 23051da177e4SLinus Torvalds tp->write_seq++; 23061da177e4SLinus Torvalds } else { 23071da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 23081da177e4SLinus Torvalds for (;;) { 2309aa133076SWu Fengguang skb = alloc_skb_fclone(MAX_TCP_HEADER, 2310aa133076SWu Fengguang sk->sk_allocation); 23111da177e4SLinus Torvalds if (skb) 23121da177e4SLinus Torvalds break; 23131da177e4SLinus Torvalds yield(); 23141da177e4SLinus Torvalds } 23151da177e4SLinus Torvalds 23161da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 23171da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 23181da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 2319e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 2320a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_FIN); 23211da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 23221da177e4SLinus Torvalds } 23239e412ba7SIlpo Järvinen __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); 23241da177e4SLinus Torvalds } 23251da177e4SLinus Torvalds 23261da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 23271da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 23281da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 232965bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 23301da177e4SLinus Torvalds */ 2331dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 23321da177e4SLinus Torvalds { 23331da177e4SLinus Torvalds struct sk_buff *skb; 23341da177e4SLinus Torvalds 23351da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 23361da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 23371da177e4SLinus Torvalds if (!skb) { 23384e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 23391da177e4SLinus Torvalds return; 23401da177e4SLinus Torvalds } 23411da177e4SLinus Torvalds 23421da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 23431da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 2344e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 2345a3433f35SChangli Gao TCPHDR_ACK | TCPHDR_RST); 23461da177e4SLinus Torvalds /* Send it off. */ 23471da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2348dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 23494e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 235026af65cbSSridhar Samudrala 235181cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 23521da177e4SLinus Torvalds } 23531da177e4SLinus Torvalds 235467edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 235567edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 23561da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 23571da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 23581da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 23591da177e4SLinus Torvalds */ 23601da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 23611da177e4SLinus Torvalds { 23621da177e4SLinus Torvalds struct sk_buff *skb; 23631da177e4SLinus Torvalds 2364fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2365a3433f35SChangli Gao if (skb == NULL || !(TCP_SKB_CB(skb)->flags & TCPHDR_SYN)) { 23661da177e4SLinus Torvalds printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); 23671da177e4SLinus Torvalds return -EFAULT; 23681da177e4SLinus Torvalds } 2369a3433f35SChangli Gao if (!(TCP_SKB_CB(skb)->flags & TCPHDR_ACK)) { 23701da177e4SLinus Torvalds if (skb_cloned(skb)) { 23711da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 23721da177e4SLinus Torvalds if (nskb == NULL) 23731da177e4SLinus Torvalds return -ENOMEM; 2374fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 23751da177e4SLinus Torvalds skb_header_release(nskb); 2376fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 23773ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 23783ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 23793ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 23801da177e4SLinus Torvalds skb = nskb; 23811da177e4SLinus Torvalds } 23821da177e4SLinus Torvalds 2383a3433f35SChangli Gao TCP_SKB_CB(skb)->flags |= TCPHDR_ACK; 23841da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 23851da177e4SLinus Torvalds } 23861da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2387dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 23881da177e4SLinus Torvalds } 23891da177e4SLinus Torvalds 239067edfef7SAndi Kleen /* Prepare a SYN-ACK. */ 23911da177e4SLinus Torvalds struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 2392e6b4d113SWilliam Allen Simpson struct request_sock *req, 2393e6b4d113SWilliam Allen Simpson struct request_values *rvp) 23941da177e4SLinus Torvalds { 2395bd0388aeSWilliam Allen Simpson struct tcp_out_options opts; 23964957faadSWilliam Allen Simpson struct tcp_extend_values *xvp = tcp_xv(rvp); 23972e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 23981da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 239928b2774aSEric Dumazet const struct tcp_cookie_values *cvp = tp->cookie_values; 24001da177e4SLinus Torvalds struct tcphdr *th; 24011da177e4SLinus Torvalds struct sk_buff *skb; 2402cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 2403bd0388aeSWilliam Allen Simpson int tcp_header_size; 2404f5fff5dcSTom Quetchenbach int mss; 240528b2774aSEric Dumazet int s_data_desired = 0; 24061da177e4SLinus Torvalds 240728b2774aSEric Dumazet if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired) 240828b2774aSEric Dumazet s_data_desired = cvp->s_data_desired; 240928b2774aSEric Dumazet skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1, GFP_ATOMIC); 24101da177e4SLinus Torvalds if (skb == NULL) 24111da177e4SLinus Torvalds return NULL; 24121da177e4SLinus Torvalds 24131da177e4SLinus Torvalds /* Reserve space for headers. */ 24141da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 24151da177e4SLinus Torvalds 2416adf30907SEric Dumazet skb_dst_set(skb, dst_clone(dst)); 24171da177e4SLinus Torvalds 2418f5fff5dcSTom Quetchenbach mss = dst_metric(dst, RTAX_ADVMSS); 2419f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) 2420f5fff5dcSTom Quetchenbach mss = tp->rx_opt.user_mss; 2421f5fff5dcSTom Quetchenbach 242233ad798cSAdam Langley if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ 242333ad798cSAdam Langley __u8 rcv_wscale; 242433ad798cSAdam Langley /* Set this up on the first call only */ 242533ad798cSAdam Langley req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); 242633ad798cSAdam Langley /* tcp_full_space because it is guaranteed to be the first packet */ 242733ad798cSAdam Langley tcp_select_initial_window(tcp_full_space(sk), 2428f5fff5dcSTom Quetchenbach mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), 242933ad798cSAdam Langley &req->rcv_wnd, 243033ad798cSAdam Langley &req->window_clamp, 243133ad798cSAdam Langley ireq->wscale_ok, 243231d12926Slaurent chavey &rcv_wscale, 243331d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 243433ad798cSAdam Langley ireq->rcv_wscale = rcv_wscale; 243533ad798cSAdam Langley } 2436cfb6eeb4SYOSHIFUJI Hideaki 243733ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 24388b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 24398b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 24408b5f12d0SFlorian Westphal TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); 24418b5f12d0SFlorian Westphal else 24428b5f12d0SFlorian Westphal #endif 244333ad798cSAdam Langley TCP_SKB_CB(skb)->when = tcp_time_stamp; 2444f5fff5dcSTom Quetchenbach tcp_header_size = tcp_synack_options(sk, req, mss, 24454957faadSWilliam Allen Simpson skb, &opts, &md5, xvp) 24464957faadSWilliam Allen Simpson + sizeof(*th); 244733ad798cSAdam Langley 2448aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 2449aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 24501da177e4SLinus Torvalds 2451aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 24521da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 24531da177e4SLinus Torvalds th->syn = 1; 24541da177e4SLinus Torvalds th->ack = 1; 24551da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 2456a3116ac5SKOVACS Krisztian th->source = ireq->loc_port; 24572e6599cbSArnaldo Carvalho de Melo th->dest = ireq->rmt_port; 2458e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 2459e870a8efSIlpo Järvinen * not even correctly set) 2460e870a8efSIlpo Järvinen */ 2461e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 2462a3433f35SChangli Gao TCPHDR_SYN | TCPHDR_ACK); 24634957faadSWilliam Allen Simpson 24644957faadSWilliam Allen Simpson if (OPTION_COOKIE_EXTENSION & opts.options) { 246528b2774aSEric Dumazet if (s_data_desired) { 246628b2774aSEric Dumazet u8 *buf = skb_put(skb, s_data_desired); 24674957faadSWilliam Allen Simpson 24684957faadSWilliam Allen Simpson /* copy data directly from the listening socket. */ 246928b2774aSEric Dumazet memcpy(buf, cvp->s_data_payload, s_data_desired); 247028b2774aSEric Dumazet TCP_SKB_CB(skb)->end_seq += s_data_desired; 24714957faadSWilliam Allen Simpson } 24724957faadSWilliam Allen Simpson 24734957faadSWilliam Allen Simpson if (opts.hash_size > 0) { 24744957faadSWilliam Allen Simpson __u32 workspace[SHA_WORKSPACE_WORDS]; 24754957faadSWilliam Allen Simpson u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS]; 24764957faadSWilliam Allen Simpson u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1]; 24774957faadSWilliam Allen Simpson 24784957faadSWilliam Allen Simpson /* Secret recipe depends on the Timestamp, (future) 24794957faadSWilliam Allen Simpson * Sequence and Acknowledgment Numbers, Initiator 24804957faadSWilliam Allen Simpson * Cookie, and others handled by IP variant caller. 24814957faadSWilliam Allen Simpson */ 24824957faadSWilliam Allen Simpson *tail-- ^= opts.tsval; 24834957faadSWilliam Allen Simpson *tail-- ^= tcp_rsk(req)->rcv_isn + 1; 24844957faadSWilliam Allen Simpson *tail-- ^= TCP_SKB_CB(skb)->seq + 1; 24854957faadSWilliam Allen Simpson 24864957faadSWilliam Allen Simpson /* recommended */ 24870eae88f3SEric Dumazet *tail-- ^= (((__force u32)th->dest << 16) | (__force u32)th->source); 2488f9a2e69eSDavid S. Miller *tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */ 24894957faadSWilliam Allen Simpson 24904957faadSWilliam Allen Simpson sha_transform((__u32 *)&xvp->cookie_bakery[0], 24914957faadSWilliam Allen Simpson (char *)mess, 24924957faadSWilliam Allen Simpson &workspace[0]); 24934957faadSWilliam Allen Simpson opts.hash_location = 24944957faadSWilliam Allen Simpson (__u8 *)&xvp->cookie_bakery[0]; 24954957faadSWilliam Allen Simpson } 24964957faadSWilliam Allen Simpson } 24974957faadSWilliam Allen Simpson 24981da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 24992e6599cbSArnaldo Carvalho de Melo th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); 25001da177e4SLinus Torvalds 25011da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 2502600ff0c2SIlpo Järvinen th->window = htons(min(req->rcv_wnd, 65535U)); 2503bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 25041da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 2505aa2ea058STom Herbert TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb)); 2506cfb6eeb4SYOSHIFUJI Hideaki 2507cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2508cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 2509cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 2510bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 251149a72dfbSAdam Langley md5, NULL, req, skb); 2512cfb6eeb4SYOSHIFUJI Hideaki } 2513cfb6eeb4SYOSHIFUJI Hideaki #endif 2514cfb6eeb4SYOSHIFUJI Hideaki 25151da177e4SLinus Torvalds return skb; 25161da177e4SLinus Torvalds } 25171da177e4SLinus Torvalds 251867edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 251940efc6faSStephen Hemminger static void tcp_connect_init(struct sock *sk) 25201da177e4SLinus Torvalds { 25211da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 25221da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 25231da177e4SLinus Torvalds __u8 rcv_wscale; 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 25261da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 25271da177e4SLinus Torvalds */ 25281da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 2529bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 25301da177e4SLinus Torvalds 2531cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2532cfb6eeb4SYOSHIFUJI Hideaki if (tp->af_specific->md5_lookup(sk, sk) != NULL) 2533cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 2534cfb6eeb4SYOSHIFUJI Hideaki #endif 2535cfb6eeb4SYOSHIFUJI Hideaki 25361da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 25371da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 25381da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 25391da177e4SLinus Torvalds tp->max_window = 0; 25405d424d5aSJohn Heffner tcp_mtup_init(sk); 25411da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 25421da177e4SLinus Torvalds 25431da177e4SLinus Torvalds if (!tp->window_clamp) 25441da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 25451da177e4SLinus Torvalds tp->advmss = dst_metric(dst, RTAX_ADVMSS); 2546f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 2547f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 2548f5fff5dcSTom Quetchenbach 25491da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 25501da177e4SLinus Torvalds 25511da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 25521da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 25531da177e4SLinus Torvalds &tp->rcv_wnd, 25541da177e4SLinus Torvalds &tp->window_clamp, 2555bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 255631d12926Slaurent chavey &rcv_wscale, 255731d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 25581da177e4SLinus Torvalds 25591da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 25601da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 25611da177e4SLinus Torvalds 25621da177e4SLinus Torvalds sk->sk_err = 0; 25631da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 25641da177e4SLinus Torvalds tp->snd_wnd = 0; 2565ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 25661da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 25671da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 256833f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 25691da177e4SLinus Torvalds tp->rcv_nxt = 0; 25701da177e4SLinus Torvalds tp->rcv_wup = 0; 25711da177e4SLinus Torvalds tp->copied_seq = 0; 25721da177e4SLinus Torvalds 2573463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 2574463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 25751da177e4SLinus Torvalds tcp_clear_retrans(tp); 25761da177e4SLinus Torvalds } 25771da177e4SLinus Torvalds 257867edfef7SAndi Kleen /* Build a SYN and send it off. */ 25791da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 25801da177e4SLinus Torvalds { 25811da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 25821da177e4SLinus Torvalds struct sk_buff *buff; 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds tcp_connect_init(sk); 25851da177e4SLinus Torvalds 2586d179cd12SDavid S. Miller buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); 25871da177e4SLinus Torvalds if (unlikely(buff == NULL)) 25881da177e4SLinus Torvalds return -ENOBUFS; 25891da177e4SLinus Torvalds 25901da177e4SLinus Torvalds /* Reserve space for headers. */ 25911da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 25921da177e4SLinus Torvalds 2593bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 2594a3433f35SChangli Gao tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); 2595e870a8efSIlpo Järvinen TCP_ECN_send_syn(sk, buff); 25961da177e4SLinus Torvalds 25971da177e4SLinus Torvalds /* Send it off. */ 25981da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 25991da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(buff)->when; 26001da177e4SLinus Torvalds skb_header_release(buff); 2601fe067e8aSDavid S. Miller __tcp_add_write_queue_tail(sk, buff); 26023ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 26033ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 26041da177e4SLinus Torvalds tp->packets_out += tcp_skb_pcount(buff); 2605aa133076SWu Fengguang tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 2606bd37a088SWei Yongjun 2607bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 2608bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 2609bd37a088SWei Yongjun */ 2610bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 2611bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 261281cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 26131da177e4SLinus Torvalds 26141da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 26153f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 26163f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 26171da177e4SLinus Torvalds return 0; 26181da177e4SLinus Torvalds } 26191da177e4SLinus Torvalds 26201da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 26211da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 26221da177e4SLinus Torvalds * for details. 26231da177e4SLinus Torvalds */ 26241da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 26251da177e4SLinus Torvalds { 2626463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 2627463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 26281da177e4SLinus Torvalds unsigned long timeout; 26291da177e4SLinus Torvalds 26301da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 2631463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 26321da177e4SLinus Torvalds int max_ato = HZ / 2; 26331da177e4SLinus Torvalds 2634056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 2635056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 26361da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 26371da177e4SLinus Torvalds 26381da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 26391da177e4SLinus Torvalds 26401da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 2641463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 26421da177e4SLinus Torvalds * directly. 26431da177e4SLinus Torvalds */ 26441da177e4SLinus Torvalds if (tp->srtt) { 26451da177e4SLinus Torvalds int rtt = max(tp->srtt >> 3, TCP_DELACK_MIN); 26461da177e4SLinus Torvalds 26471da177e4SLinus Torvalds if (rtt < max_ato) 26481da177e4SLinus Torvalds max_ato = rtt; 26491da177e4SLinus Torvalds } 26501da177e4SLinus Torvalds 26511da177e4SLinus Torvalds ato = min(ato, max_ato); 26521da177e4SLinus Torvalds } 26531da177e4SLinus Torvalds 26541da177e4SLinus Torvalds /* Stay within the limit we were given */ 26551da177e4SLinus Torvalds timeout = jiffies + ato; 26561da177e4SLinus Torvalds 26571da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 2658463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 26591da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 26601da177e4SLinus Torvalds * send ACK now. 26611da177e4SLinus Torvalds */ 2662463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 2663463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 26641da177e4SLinus Torvalds tcp_send_ack(sk); 26651da177e4SLinus Torvalds return; 26661da177e4SLinus Torvalds } 26671da177e4SLinus Torvalds 2668463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 2669463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 26701da177e4SLinus Torvalds } 2671463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 2672463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 2673463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 26741da177e4SLinus Torvalds } 26751da177e4SLinus Torvalds 26761da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 26771da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 26781da177e4SLinus Torvalds { 26791da177e4SLinus Torvalds struct sk_buff *buff; 26801da177e4SLinus Torvalds 2681058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 2682058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 2683058dc334SIlpo Järvinen return; 2684058dc334SIlpo Järvinen 26851da177e4SLinus Torvalds /* We are not putting this on the write queue, so 26861da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 26871da177e4SLinus Torvalds * sock. 26881da177e4SLinus Torvalds */ 26891da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 26901da177e4SLinus Torvalds if (buff == NULL) { 2691463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 2692463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 26933f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 26943f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 26951da177e4SLinus Torvalds return; 26961da177e4SLinus Torvalds } 26971da177e4SLinus Torvalds 26981da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 26991da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 2700a3433f35SChangli Gao tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); 27011da177e4SLinus Torvalds 27021da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 27031da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 2704dfb4b9dcSDavid S. Miller tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC); 27051da177e4SLinus Torvalds } 27061da177e4SLinus Torvalds 27071da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 27081da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 27091da177e4SLinus Torvalds * 27101da177e4SLinus Torvalds * Question: what should we make while urgent mode? 27111da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 27121da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 27131da177e4SLinus Torvalds * 27141da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 27151da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 27161da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 27171da177e4SLinus Torvalds */ 27181da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 27191da177e4SLinus Torvalds { 27201da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27211da177e4SLinus Torvalds struct sk_buff *skb; 27221da177e4SLinus Torvalds 27231da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 27241da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 27251da177e4SLinus Torvalds if (skb == NULL) 27261da177e4SLinus Torvalds return -1; 27271da177e4SLinus Torvalds 27281da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 27291da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 27301da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 27311da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 27321da177e4SLinus Torvalds * send it. 27331da177e4SLinus Torvalds */ 2734a3433f35SChangli Gao tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); 27351da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2736dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); 27371da177e4SLinus Torvalds } 27381da177e4SLinus Torvalds 273967edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 27401da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 27411da177e4SLinus Torvalds { 27421da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27431da177e4SLinus Torvalds struct sk_buff *skb; 27441da177e4SLinus Torvalds 2745058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 2746058dc334SIlpo Järvinen return -1; 2747058dc334SIlpo Järvinen 2748fe067e8aSDavid S. Miller if ((skb = tcp_send_head(sk)) != NULL && 274990840defSIlpo Järvinen before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 27501da177e4SLinus Torvalds int err; 27510c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 275290840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 27531da177e4SLinus Torvalds 27541da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 27551da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 27561da177e4SLinus Torvalds 27571da177e4SLinus Torvalds /* We are probing the opening of a window 27581da177e4SLinus Torvalds * but the window size is != 0 27591da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 27601da177e4SLinus Torvalds */ 27611da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 27621da177e4SLinus Torvalds skb->len > mss) { 27631da177e4SLinus Torvalds seg_size = min(seg_size, mss); 2764a3433f35SChangli Gao TCP_SKB_CB(skb)->flags |= TCPHDR_PSH; 2765846998aeSDavid S. Miller if (tcp_fragment(sk, skb, seg_size, mss)) 27661da177e4SLinus Torvalds return -1; 27671da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 2768846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 27691da177e4SLinus Torvalds 2770a3433f35SChangli Gao TCP_SKB_CB(skb)->flags |= TCPHDR_PSH; 27711da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2772dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 277366f5fe62SIlpo Järvinen if (!err) 277466f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 27751da177e4SLinus Torvalds return err; 27761da177e4SLinus Torvalds } else { 277733f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 27784828e7f4SIlpo Järvinen tcp_xmit_probe_skb(sk, 1); 27791da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 27801da177e4SLinus Torvalds } 27811da177e4SLinus Torvalds } 27821da177e4SLinus Torvalds 27831da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 27841da177e4SLinus Torvalds * a partial packet else a zero probe. 27851da177e4SLinus Torvalds */ 27861da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 27871da177e4SLinus Torvalds { 2788463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 27891da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27901da177e4SLinus Torvalds int err; 27911da177e4SLinus Torvalds 27921da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 27931da177e4SLinus Torvalds 2794fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 27951da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 27966687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 2797463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 27981da177e4SLinus Torvalds return; 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds if (err <= 0) { 2802463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_backoff < sysctl_tcp_retries2) 2803463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 28046687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 2805463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 28063f421baaSArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), 28073f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 28081da177e4SLinus Torvalds } else { 28091da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 28106687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 28111da177e4SLinus Torvalds * Let local senders to fight for local resources. 28121da177e4SLinus Torvalds * 28131da177e4SLinus Torvalds * Use accumulated backoff yet. 28141da177e4SLinus Torvalds */ 28156687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 28166687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 2817463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 2818463c84b9SArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, 28193f421baaSArnaldo Carvalho de Melo TCP_RESOURCE_PROBE_INTERVAL), 28203f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 28211da177e4SLinus Torvalds } 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds 2824c6aefafbSGlenn Griffin EXPORT_SYMBOL(tcp_select_initial_window); 28251da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_connect); 28261da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_make_synack); 28271da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_simple_retransmit); 28281da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_sync_mss); 28295d424d5aSJohn Heffner EXPORT_SYMBOL(tcp_mtup_init); 2830