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 { 297bdf1ee5dSIlpo Järvinen TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_CWR; 298bdf1ee5dSIlpo Järvinen if (!(tp->ecn_flags & TCP_ECN_OK)) 299bdf1ee5dSIlpo Järvinen TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_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) { 309bdf1ee5dSIlpo Järvinen TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ECE | TCPCB_FLAG_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 { 353*2e8e18efSDavid 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; 364e870a8efSIlpo Järvinen if (flags & (TCPCB_FLAG_SYN | TCPCB_FLAG_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; 6714957faadSWilliam Allen Simpson bool doing_ts = ireq->tstamp_ok; 67233ad798cSAdam Langley 67333ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 67433ad798cSAdam Langley *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); 67533ad798cSAdam Langley if (*md5) { 67633ad798cSAdam Langley opts->options |= OPTION_MD5; 6774957faadSWilliam Allen Simpson remaining -= TCPOLEN_MD5SIG_ALIGNED; 6784957faadSWilliam Allen Simpson 6794957faadSWilliam Allen Simpson /* We can't fit any SACK blocks in a packet with MD5 + TS 6804957faadSWilliam Allen Simpson * options. There was discussion about disabling SACK 6814957faadSWilliam Allen Simpson * rather than TS in order to fit in better with old, 6824957faadSWilliam Allen Simpson * buggy kernels, but that was deemed to be unnecessary. 6834957faadSWilliam Allen Simpson */ 6844957faadSWilliam Allen Simpson doing_ts &= !ireq->sack_ok; 68533ad798cSAdam Langley } 68633ad798cSAdam Langley #else 68733ad798cSAdam Langley *md5 = NULL; 68833ad798cSAdam Langley #endif 68933ad798cSAdam Langley 6904957faadSWilliam Allen Simpson /* We always send an MSS option. */ 69133ad798cSAdam Langley opts->mss = mss; 6924957faadSWilliam Allen Simpson remaining -= TCPOLEN_MSS_ALIGNED; 69333ad798cSAdam Langley 69433ad798cSAdam Langley if (likely(ireq->wscale_ok)) { 69533ad798cSAdam Langley opts->ws = ireq->rcv_wscale; 69689e95a61SOri Finkelman opts->options |= OPTION_WSCALE; 6974957faadSWilliam Allen Simpson remaining -= TCPOLEN_WSCALE_ALIGNED; 69833ad798cSAdam Langley } 69933ad798cSAdam Langley if (likely(doing_ts)) { 70033ad798cSAdam Langley opts->options |= OPTION_TS; 70133ad798cSAdam Langley opts->tsval = TCP_SKB_CB(skb)->when; 70233ad798cSAdam Langley opts->tsecr = req->ts_recent; 7034957faadSWilliam Allen Simpson remaining -= TCPOLEN_TSTAMP_ALIGNED; 70433ad798cSAdam Langley } 70533ad798cSAdam Langley if (likely(ireq->sack_ok)) { 70633ad798cSAdam Langley opts->options |= OPTION_SACK_ADVERTISE; 70733ad798cSAdam Langley if (unlikely(!doing_ts)) 7084957faadSWilliam Allen Simpson remaining -= TCPOLEN_SACKPERM_ALIGNED; 70933ad798cSAdam Langley } 71033ad798cSAdam Langley 7114957faadSWilliam Allen Simpson /* Similar rationale to tcp_syn_options() applies here, too. 7124957faadSWilliam Allen Simpson * If the <SYN> options fit, the same options should fit now! 7134957faadSWilliam Allen Simpson */ 7144957faadSWilliam Allen Simpson if (*md5 == NULL && 7154957faadSWilliam Allen Simpson doing_ts && 7164957faadSWilliam Allen Simpson cookie_plus > TCPOLEN_COOKIE_BASE) { 7174957faadSWilliam Allen Simpson int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */ 7184957faadSWilliam Allen Simpson 7194957faadSWilliam Allen Simpson if (0x2 & need) { 7204957faadSWilliam Allen Simpson /* 32-bit multiple */ 7214957faadSWilliam Allen Simpson need += 2; /* NOPs */ 7224957faadSWilliam Allen Simpson } 7234957faadSWilliam Allen Simpson if (need <= remaining) { 7244957faadSWilliam Allen Simpson opts->options |= OPTION_COOKIE_EXTENSION; 7254957faadSWilliam Allen Simpson opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE; 7264957faadSWilliam Allen Simpson remaining -= need; 7274957faadSWilliam Allen Simpson } else { 7284957faadSWilliam Allen Simpson /* There's no error return, so flag it. */ 7294957faadSWilliam Allen Simpson xvp->cookie_out_never = 1; /* true */ 7304957faadSWilliam Allen Simpson opts->hash_size = 0; 7314957faadSWilliam Allen Simpson } 7324957faadSWilliam Allen Simpson } 7334957faadSWilliam Allen Simpson return MAX_TCP_OPTION_SPACE - remaining; 73433ad798cSAdam Langley } 73533ad798cSAdam Langley 73667edfef7SAndi Kleen /* Compute TCP options for ESTABLISHED sockets. This is not the 73767edfef7SAndi Kleen * final wire format yet. 73867edfef7SAndi Kleen */ 73933ad798cSAdam Langley static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb, 74033ad798cSAdam Langley struct tcp_out_options *opts, 74133ad798cSAdam Langley struct tcp_md5sig_key **md5) { 74233ad798cSAdam Langley struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; 74333ad798cSAdam Langley struct tcp_sock *tp = tcp_sk(sk); 74433ad798cSAdam Langley unsigned size = 0; 745cabeccbdSIlpo Järvinen unsigned int eff_sacks; 74633ad798cSAdam Langley 74733ad798cSAdam Langley #ifdef CONFIG_TCP_MD5SIG 74833ad798cSAdam Langley *md5 = tp->af_specific->md5_lookup(sk, sk); 74933ad798cSAdam Langley if (unlikely(*md5)) { 75033ad798cSAdam Langley opts->options |= OPTION_MD5; 75133ad798cSAdam Langley size += TCPOLEN_MD5SIG_ALIGNED; 75233ad798cSAdam Langley } 75333ad798cSAdam Langley #else 75433ad798cSAdam Langley *md5 = NULL; 75533ad798cSAdam Langley #endif 75633ad798cSAdam Langley 75733ad798cSAdam Langley if (likely(tp->rx_opt.tstamp_ok)) { 75833ad798cSAdam Langley opts->options |= OPTION_TS; 75933ad798cSAdam Langley opts->tsval = tcb ? tcb->when : 0; 76033ad798cSAdam Langley opts->tsecr = tp->rx_opt.ts_recent; 76133ad798cSAdam Langley size += TCPOLEN_TSTAMP_ALIGNED; 76233ad798cSAdam Langley } 76333ad798cSAdam Langley 764cabeccbdSIlpo Järvinen eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; 765cabeccbdSIlpo Järvinen if (unlikely(eff_sacks)) { 76633ad798cSAdam Langley const unsigned remaining = MAX_TCP_OPTION_SPACE - size; 76733ad798cSAdam Langley opts->num_sack_blocks = 768cabeccbdSIlpo Järvinen min_t(unsigned, eff_sacks, 76933ad798cSAdam Langley (remaining - TCPOLEN_SACK_BASE_ALIGNED) / 77033ad798cSAdam Langley TCPOLEN_SACK_PERBLOCK); 77133ad798cSAdam Langley size += TCPOLEN_SACK_BASE_ALIGNED + 77233ad798cSAdam Langley opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; 77333ad798cSAdam Langley } 77433ad798cSAdam Langley 77533ad798cSAdam Langley return size; 77640efc6faSStephen Hemminger } 7771da177e4SLinus Torvalds 7781da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 7791da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 7801da177e4SLinus Torvalds * transmission and possible later retransmissions. 7811da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 7821da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 7831da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 7841da177e4SLinus Torvalds * device. 7851da177e4SLinus Torvalds * 7861da177e4SLinus Torvalds * We are working here with either a clone of the original 7871da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 7881da177e4SLinus Torvalds */ 789056834d9SIlpo Järvinen static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 790056834d9SIlpo Järvinen gfp_t gfp_mask) 7911da177e4SLinus Torvalds { 7926687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 793dfb4b9dcSDavid S. Miller struct inet_sock *inet; 794dfb4b9dcSDavid S. Miller struct tcp_sock *tp; 795dfb4b9dcSDavid S. Miller struct tcp_skb_cb *tcb; 79633ad798cSAdam Langley struct tcp_out_options opts; 79733ad798cSAdam Langley unsigned tcp_options_size, tcp_header_size; 798cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 7991da177e4SLinus Torvalds struct tcphdr *th; 8001da177e4SLinus Torvalds int err; 8011da177e4SLinus Torvalds 802dfb4b9dcSDavid S. Miller BUG_ON(!skb || !tcp_skb_pcount(skb)); 803dfb4b9dcSDavid S. Miller 804dfb4b9dcSDavid S. Miller /* If congestion control is doing timestamping, we must 805dfb4b9dcSDavid S. Miller * take such a timestamp before we potentially clone/copy. 806dfb4b9dcSDavid S. Miller */ 807164891aaSStephen Hemminger if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) 808dfb4b9dcSDavid S. Miller __net_timestamp(skb); 809dfb4b9dcSDavid S. Miller 810dfb4b9dcSDavid S. Miller if (likely(clone_it)) { 811dfb4b9dcSDavid S. Miller if (unlikely(skb_cloned(skb))) 812dfb4b9dcSDavid S. Miller skb = pskb_copy(skb, gfp_mask); 813dfb4b9dcSDavid S. Miller else 814dfb4b9dcSDavid S. Miller skb = skb_clone(skb, gfp_mask); 815dfb4b9dcSDavid S. Miller if (unlikely(!skb)) 816dfb4b9dcSDavid S. Miller return -ENOBUFS; 817dfb4b9dcSDavid S. Miller } 818dfb4b9dcSDavid S. Miller 819dfb4b9dcSDavid S. Miller inet = inet_sk(sk); 820dfb4b9dcSDavid S. Miller tp = tcp_sk(sk); 821dfb4b9dcSDavid S. Miller tcb = TCP_SKB_CB(skb); 82233ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 8231da177e4SLinus Torvalds 82433ad798cSAdam Langley if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) 82533ad798cSAdam Langley tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); 82633ad798cSAdam Langley else 82733ad798cSAdam Langley tcp_options_size = tcp_established_options(sk, skb, &opts, 82833ad798cSAdam Langley &md5); 82933ad798cSAdam Langley tcp_header_size = tcp_options_size + sizeof(struct tcphdr); 8301da177e4SLinus Torvalds 831317a76f9SStephen Hemminger if (tcp_packets_in_flight(tp) == 0) 8326687e988SArnaldo Carvalho de Melo tcp_ca_event(sk, CA_EVENT_TX_START); 8331da177e4SLinus Torvalds 834aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 835aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 836e89862f4SDavid S. Miller skb_set_owner_w(skb, sk); 8371da177e4SLinus Torvalds 8381da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 839aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 840c720c7e8SEric Dumazet th->source = inet->inet_sport; 841c720c7e8SEric Dumazet th->dest = inet->inet_dport; 8421da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 8431da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 844df7a3b07SAl Viro *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | 845dfb4b9dcSDavid S. Miller tcb->flags); 846dfb4b9dcSDavid S. Miller 847dfb4b9dcSDavid S. Miller if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { 8481da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 8491da177e4SLinus Torvalds * is never scaled. 8501da177e4SLinus Torvalds */ 851600ff0c2SIlpo Järvinen th->window = htons(min(tp->rcv_wnd, 65535U)); 8521da177e4SLinus Torvalds } else { 8531da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 8541da177e4SLinus Torvalds } 8551da177e4SLinus Torvalds th->check = 0; 8561da177e4SLinus Torvalds th->urg_ptr = 0; 8571da177e4SLinus Torvalds 85833f5f57eSIlpo Järvinen /* The urg_mode check is necessary during a below snd_una win probe */ 8597691367dSHerbert Xu if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { 8607691367dSHerbert Xu if (before(tp->snd_up, tcb->seq + 0x10000)) { 8611da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up - tcb->seq); 8621da177e4SLinus Torvalds th->urg = 1; 8637691367dSHerbert Xu } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { 8647691367dSHerbert Xu th->urg_ptr = 0xFFFF; 8657691367dSHerbert Xu th->urg = 1; 8667691367dSHerbert Xu } 8671da177e4SLinus Torvalds } 8681da177e4SLinus Torvalds 869bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 87033ad798cSAdam Langley if (likely((tcb->flags & TCPCB_FLAG_SYN) == 0)) 8719e412ba7SIlpo Järvinen TCP_ECN_send(sk, skb, tcp_header_size); 872dfb4b9dcSDavid S. Miller 873cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 874cfb6eeb4SYOSHIFUJI Hideaki /* Calculate the MD5 hash, as we have all we need now */ 875cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 87633ad798cSAdam Langley sk->sk_route_caps &= ~NETIF_F_GSO_MASK; 877bd0388aeSWilliam Allen Simpson tp->af_specific->calc_md5_hash(opts.hash_location, 87849a72dfbSAdam Langley md5, sk, NULL, skb); 879cfb6eeb4SYOSHIFUJI Hideaki } 880cfb6eeb4SYOSHIFUJI Hideaki #endif 881cfb6eeb4SYOSHIFUJI Hideaki 882bb296246SHerbert Xu icsk->icsk_af_ops->send_check(sk, skb); 8831da177e4SLinus Torvalds 884dfb4b9dcSDavid S. Miller if (likely(tcb->flags & TCPCB_FLAG_ACK)) 885fc6415bcSDavid S. Miller tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); 8861da177e4SLinus Torvalds 8871da177e4SLinus Torvalds if (skb->len != tcp_header_size) 8881da177e4SLinus Torvalds tcp_event_data_sent(tp, skb, sk); 8891da177e4SLinus Torvalds 890bd37a088SWei Yongjun if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) 89181cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 8921da177e4SLinus Torvalds 893e89862f4SDavid S. Miller err = icsk->icsk_af_ops->queue_xmit(skb, 0); 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; 10261da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN | TCPCB_FLAG_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. */ 1331104439a8SJohn Heffner if ((TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && 1332104439a8SJohn Heffner tcp_skb_pcount(skb) == 1) 1333c1b4a7e6SDavid S. Miller return 1; 1334c1b4a7e6SDavid S. Miller 1335c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1336c1b4a7e6SDavid S. Miller cwnd = tp->snd_cwnd; 1337c1b4a7e6SDavid S. Miller if (in_flight < cwnd) 1338c1b4a7e6SDavid S. Miller return (cwnd - in_flight); 1339c1b4a7e6SDavid S. Miller 1340c1b4a7e6SDavid S. Miller return 0; 1341c1b4a7e6SDavid S. Miller } 1342c1b4a7e6SDavid S. Miller 134367edfef7SAndi Kleen /* Intialize TSO state of a skb. 134467edfef7SAndi Kleen * This must be invoked the first time we consider transmitting 1345c1b4a7e6SDavid S. Miller * SKB onto the wire. 1346c1b4a7e6SDavid S. Miller */ 1347056834d9SIlpo Järvinen static int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, 1348056834d9SIlpo Järvinen unsigned int mss_now) 1349c1b4a7e6SDavid S. Miller { 1350c1b4a7e6SDavid S. Miller int tso_segs = tcp_skb_pcount(skb); 1351c1b4a7e6SDavid S. Miller 1352f8269a49SIlpo Järvinen if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { 1353846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1354c1b4a7e6SDavid S. Miller tso_segs = tcp_skb_pcount(skb); 1355c1b4a7e6SDavid S. Miller } 1356c1b4a7e6SDavid S. Miller return tso_segs; 1357c1b4a7e6SDavid S. Miller } 1358c1b4a7e6SDavid S. Miller 135967edfef7SAndi Kleen /* Minshall's variant of the Nagle send check. */ 1360c1b4a7e6SDavid S. Miller static inline int tcp_minshall_check(const struct tcp_sock *tp) 1361c1b4a7e6SDavid S. Miller { 1362c1b4a7e6SDavid S. Miller return after(tp->snd_sml, tp->snd_una) && 1363c1b4a7e6SDavid S. Miller !after(tp->snd_sml, tp->snd_nxt); 1364c1b4a7e6SDavid S. Miller } 1365c1b4a7e6SDavid S. Miller 1366c1b4a7e6SDavid S. Miller /* Return 0, if packet can be sent now without violation Nagle's rules: 1367c1b4a7e6SDavid S. Miller * 1. It is full sized. 1368c1b4a7e6SDavid S. Miller * 2. Or it contains FIN. (already checked by caller) 1369c1b4a7e6SDavid S. Miller * 3. Or TCP_NODELAY was set. 1370c1b4a7e6SDavid S. Miller * 4. Or TCP_CORK is not set, and all sent packets are ACKed. 1371c1b4a7e6SDavid S. Miller * With Minshall's modification: all sent small packets are ACKed. 1372c1b4a7e6SDavid S. Miller */ 1373c1b4a7e6SDavid S. Miller static inline int tcp_nagle_check(const struct tcp_sock *tp, 1374c1b4a7e6SDavid S. Miller const struct sk_buff *skb, 1375c1b4a7e6SDavid S. Miller unsigned mss_now, int nonagle) 1376c1b4a7e6SDavid S. Miller { 1377c1b4a7e6SDavid S. Miller return (skb->len < mss_now && 1378c1b4a7e6SDavid S. Miller ((nonagle & TCP_NAGLE_CORK) || 1379056834d9SIlpo Järvinen (!nonagle && tp->packets_out && tcp_minshall_check(tp)))); 1380c1b4a7e6SDavid S. Miller } 1381c1b4a7e6SDavid S. Miller 1382c1b4a7e6SDavid S. Miller /* Return non-zero if the Nagle test allows this packet to be 1383c1b4a7e6SDavid S. Miller * sent now. 1384c1b4a7e6SDavid S. Miller */ 1385c1b4a7e6SDavid S. Miller static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, 1386c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1387c1b4a7e6SDavid S. Miller { 1388c1b4a7e6SDavid S. Miller /* Nagle rule does not apply to frames, which sit in the middle of the 1389c1b4a7e6SDavid S. Miller * write_queue (they have no chances to get new data). 1390c1b4a7e6SDavid S. Miller * 1391c1b4a7e6SDavid S. Miller * This is implemented in the callers, where they modify the 'nonagle' 1392c1b4a7e6SDavid S. Miller * argument based upon the location of SKB in the send queue. 1393c1b4a7e6SDavid S. Miller */ 1394c1b4a7e6SDavid S. Miller if (nonagle & TCP_NAGLE_PUSH) 1395c1b4a7e6SDavid S. Miller return 1; 1396c1b4a7e6SDavid S. Miller 1397d551e454SIlpo Järvinen /* Don't use the nagle rule for urgent data (or for the final FIN). 1398d551e454SIlpo Järvinen * Nagle can be ignored during F-RTO too (see RFC4138). 1399d551e454SIlpo Järvinen */ 140033f5f57eSIlpo Järvinen if (tcp_urg_mode(tp) || (tp->frto_counter == 2) || 1401c1b4a7e6SDavid S. Miller (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) 1402c1b4a7e6SDavid S. Miller return 1; 1403c1b4a7e6SDavid S. Miller 1404c1b4a7e6SDavid S. Miller if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) 1405c1b4a7e6SDavid S. Miller return 1; 1406c1b4a7e6SDavid S. Miller 1407c1b4a7e6SDavid S. Miller return 0; 1408c1b4a7e6SDavid S. Miller } 1409c1b4a7e6SDavid S. Miller 1410c1b4a7e6SDavid S. Miller /* Does at least the first segment of SKB fit into the send window? */ 1411056834d9SIlpo Järvinen static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, 1412056834d9SIlpo Järvinen unsigned int cur_mss) 1413c1b4a7e6SDavid S. Miller { 1414c1b4a7e6SDavid S. Miller u32 end_seq = TCP_SKB_CB(skb)->end_seq; 1415c1b4a7e6SDavid S. Miller 1416c1b4a7e6SDavid S. Miller if (skb->len > cur_mss) 1417c1b4a7e6SDavid S. Miller end_seq = TCP_SKB_CB(skb)->seq + cur_mss; 1418c1b4a7e6SDavid S. Miller 141990840defSIlpo Järvinen return !after(end_seq, tcp_wnd_end(tp)); 1420c1b4a7e6SDavid S. Miller } 1421c1b4a7e6SDavid S. Miller 1422fe067e8aSDavid S. Miller /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) 1423c1b4a7e6SDavid S. Miller * should be put on the wire right now. If so, it returns the number of 1424c1b4a7e6SDavid S. Miller * packets allowed by the congestion window. 1425c1b4a7e6SDavid S. Miller */ 1426c1b4a7e6SDavid S. Miller static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, 1427c1b4a7e6SDavid S. Miller unsigned int cur_mss, int nonagle) 1428c1b4a7e6SDavid S. Miller { 1429c1b4a7e6SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 1430c1b4a7e6SDavid S. Miller unsigned int cwnd_quota; 1431c1b4a7e6SDavid S. Miller 1432846998aeSDavid S. Miller tcp_init_tso_segs(sk, skb, cur_mss); 1433c1b4a7e6SDavid S. Miller 1434c1b4a7e6SDavid S. Miller if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) 1435c1b4a7e6SDavid S. Miller return 0; 1436c1b4a7e6SDavid S. Miller 1437c1b4a7e6SDavid S. Miller cwnd_quota = tcp_cwnd_test(tp, skb); 1438056834d9SIlpo Järvinen if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) 1439c1b4a7e6SDavid S. Miller cwnd_quota = 0; 1440c1b4a7e6SDavid S. Miller 1441c1b4a7e6SDavid S. Miller return cwnd_quota; 1442c1b4a7e6SDavid S. Miller } 1443c1b4a7e6SDavid S. Miller 144467edfef7SAndi Kleen /* Test if sending is allowed right now. */ 14459e412ba7SIlpo Järvinen int tcp_may_send_now(struct sock *sk) 1446c1b4a7e6SDavid S. Miller { 14479e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 1448fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1449c1b4a7e6SDavid S. Miller 1450c1b4a7e6SDavid S. Miller return (skb && 14510c54b85fSIlpo Järvinen tcp_snd_test(sk, skb, tcp_current_mss(sk), 1452c1b4a7e6SDavid S. Miller (tcp_skb_is_last(sk, skb) ? 14534e67d876SIlpo Järvinen tp->nonagle : TCP_NAGLE_PUSH))); 1454c1b4a7e6SDavid S. Miller } 1455c1b4a7e6SDavid S. Miller 1456c1b4a7e6SDavid S. Miller /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet 1457c1b4a7e6SDavid S. Miller * which is put after SKB on the list. It is very much like 1458c1b4a7e6SDavid S. Miller * tcp_fragment() except that it may make several kinds of assumptions 1459c1b4a7e6SDavid S. Miller * in order to speed up the splitting operation. In particular, we 1460c1b4a7e6SDavid S. Miller * know that all the data is in scatter-gather pages, and that the 1461c1b4a7e6SDavid S. Miller * packet has never been sent out before (and thus is not cloned). 1462c1b4a7e6SDavid S. Miller */ 1463056834d9SIlpo Järvinen static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 1464056834d9SIlpo Järvinen unsigned int mss_now) 1465c1b4a7e6SDavid S. Miller { 1466c1b4a7e6SDavid S. Miller struct sk_buff *buff; 1467c1b4a7e6SDavid S. Miller int nlen = skb->len - len; 14689ce01461SIlpo Järvinen u8 flags; 1469c1b4a7e6SDavid S. Miller 1470c1b4a7e6SDavid S. Miller /* All of a TSO frame must be composed of paged data. */ 1471c8ac3774SHerbert Xu if (skb->len != skb->data_len) 1472c8ac3774SHerbert Xu return tcp_fragment(sk, skb, len, mss_now); 1473c1b4a7e6SDavid S. Miller 1474df97c708SPavel Emelyanov buff = sk_stream_alloc_skb(sk, 0, GFP_ATOMIC); 1475c1b4a7e6SDavid S. Miller if (unlikely(buff == NULL)) 1476c1b4a7e6SDavid S. Miller return -ENOMEM; 1477c1b4a7e6SDavid S. Miller 14783ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 14793ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 1480b60b49eaSHerbert Xu buff->truesize += nlen; 1481c1b4a7e6SDavid S. Miller skb->truesize -= nlen; 1482c1b4a7e6SDavid S. Miller 1483c1b4a7e6SDavid S. Miller /* Correct the sequence numbers. */ 1484c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 1485c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 1486c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 1487c1b4a7e6SDavid S. Miller 1488c1b4a7e6SDavid S. Miller /* PSH and FIN should only be set in the second packet. */ 1489c1b4a7e6SDavid S. Miller flags = TCP_SKB_CB(skb)->flags; 1490c1b4a7e6SDavid S. Miller TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN | TCPCB_FLAG_PSH); 1491c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->flags = flags; 1492c1b4a7e6SDavid S. Miller 1493c1b4a7e6SDavid S. Miller /* This packet was never sent out yet, so no SACK bits. */ 1494c1b4a7e6SDavid S. Miller TCP_SKB_CB(buff)->sacked = 0; 1495c1b4a7e6SDavid S. Miller 149684fa7933SPatrick McHardy buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL; 1497c1b4a7e6SDavid S. Miller skb_split(skb, buff, len); 1498c1b4a7e6SDavid S. Miller 1499c1b4a7e6SDavid S. Miller /* Fix up tso_factor for both original and new SKB. */ 1500846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss_now); 1501846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, buff, mss_now); 1502c1b4a7e6SDavid S. Miller 1503c1b4a7e6SDavid S. Miller /* Link BUFF into the send queue. */ 1504c1b4a7e6SDavid S. Miller skb_header_release(buff); 1505fe067e8aSDavid S. Miller tcp_insert_write_queue_after(skb, buff, sk); 1506c1b4a7e6SDavid S. Miller 1507c1b4a7e6SDavid S. Miller return 0; 1508c1b4a7e6SDavid S. Miller } 1509c1b4a7e6SDavid S. Miller 1510c1b4a7e6SDavid S. Miller /* Try to defer sending, if possible, in order to minimize the amount 1511c1b4a7e6SDavid S. Miller * of TSO splitting we do. View it as a kind of TSO Nagle test. 1512c1b4a7e6SDavid S. Miller * 1513c1b4a7e6SDavid S. Miller * This algorithm is from John Heffner. 1514c1b4a7e6SDavid S. Miller */ 15159e412ba7SIlpo Järvinen static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) 1516c1b4a7e6SDavid S. Miller { 15179e412ba7SIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 15186687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 1519c1b4a7e6SDavid S. Miller u32 send_win, cong_win, limit, in_flight; 1520c1b4a7e6SDavid S. Miller 1521c1b4a7e6SDavid S. Miller if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) 1522ae8064acSJohn Heffner goto send_now; 1523c1b4a7e6SDavid S. Miller 15246687e988SArnaldo Carvalho de Melo if (icsk->icsk_ca_state != TCP_CA_Open) 1525ae8064acSJohn Heffner goto send_now; 1526ae8064acSJohn Heffner 1527ae8064acSJohn Heffner /* Defer for less than two clock ticks. */ 1528bd515c3eSIlpo Järvinen if (tp->tso_deferred && 1529a2acde07SIlpo Järvinen (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1) 1530ae8064acSJohn Heffner goto send_now; 1531908a75c1SDavid S. Miller 1532c1b4a7e6SDavid S. Miller in_flight = tcp_packets_in_flight(tp); 1533c1b4a7e6SDavid S. Miller 1534056834d9SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight)); 1535c1b4a7e6SDavid S. Miller 153690840defSIlpo Järvinen send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 1537c1b4a7e6SDavid S. Miller 1538c1b4a7e6SDavid S. Miller /* From in_flight test above, we know that cwnd > in_flight. */ 1539c1b4a7e6SDavid S. Miller cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; 1540c1b4a7e6SDavid S. Miller 1541c1b4a7e6SDavid S. Miller limit = min(send_win, cong_win); 1542c1b4a7e6SDavid S. Miller 1543ba244fe9SDavid S. Miller /* If a full-sized TSO skb can be sent, do it. */ 154482cc1a7aSPeter P Waskiewicz Jr if (limit >= sk->sk_gso_max_size) 1545ae8064acSJohn Heffner goto send_now; 1546ba244fe9SDavid S. Miller 154762ad2761SIlpo Järvinen /* Middle in queue won't get any more data, full sendable already? */ 154862ad2761SIlpo Järvinen if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) 154962ad2761SIlpo Järvinen goto send_now; 155062ad2761SIlpo Järvinen 1551c1b4a7e6SDavid S. Miller if (sysctl_tcp_tso_win_divisor) { 1552c1b4a7e6SDavid S. Miller u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); 1553c1b4a7e6SDavid S. Miller 1554c1b4a7e6SDavid S. Miller /* If at least some fraction of a window is available, 1555c1b4a7e6SDavid S. Miller * just use it. 1556c1b4a7e6SDavid S. Miller */ 1557c1b4a7e6SDavid S. Miller chunk /= sysctl_tcp_tso_win_divisor; 1558c1b4a7e6SDavid S. Miller if (limit >= chunk) 1559ae8064acSJohn Heffner goto send_now; 1560c1b4a7e6SDavid S. Miller } else { 1561c1b4a7e6SDavid S. Miller /* Different approach, try not to defer past a single 1562c1b4a7e6SDavid S. Miller * ACK. Receiver should ACK every other full sized 1563c1b4a7e6SDavid S. Miller * frame, so if we have space for more than 3 frames 1564c1b4a7e6SDavid S. Miller * then send now. 1565c1b4a7e6SDavid S. Miller */ 1566c1b4a7e6SDavid S. Miller if (limit > tcp_max_burst(tp) * tp->mss_cache) 1567ae8064acSJohn Heffner goto send_now; 1568c1b4a7e6SDavid S. Miller } 1569c1b4a7e6SDavid S. Miller 1570c1b4a7e6SDavid S. Miller /* Ok, it looks like it is advisable to defer. */ 1571ae8064acSJohn Heffner tp->tso_deferred = 1 | (jiffies << 1); 1572ae8064acSJohn Heffner 1573c1b4a7e6SDavid S. Miller return 1; 1574ae8064acSJohn Heffner 1575ae8064acSJohn Heffner send_now: 1576ae8064acSJohn Heffner tp->tso_deferred = 0; 1577ae8064acSJohn Heffner return 0; 1578c1b4a7e6SDavid S. Miller } 1579c1b4a7e6SDavid S. Miller 15805d424d5aSJohn Heffner /* Create a new MTU probe if we are ready. 158167edfef7SAndi Kleen * MTU probe is regularly attempting to increase the path MTU by 158267edfef7SAndi Kleen * deliberately sending larger packets. This discovers routing 158367edfef7SAndi Kleen * changes resulting in larger path MTUs. 158467edfef7SAndi Kleen * 15855d424d5aSJohn Heffner * Returns 0 if we should wait to probe (no cwnd available), 15865d424d5aSJohn Heffner * 1 if a probe was sent, 1587056834d9SIlpo Järvinen * -1 otherwise 1588056834d9SIlpo Järvinen */ 15895d424d5aSJohn Heffner static int tcp_mtu_probe(struct sock *sk) 15905d424d5aSJohn Heffner { 15915d424d5aSJohn Heffner struct tcp_sock *tp = tcp_sk(sk); 15925d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 15935d424d5aSJohn Heffner struct sk_buff *skb, *nskb, *next; 15945d424d5aSJohn Heffner int len; 15955d424d5aSJohn Heffner int probe_size; 159691cc17c0SIlpo Järvinen int size_needed; 15975d424d5aSJohn Heffner int copy; 15985d424d5aSJohn Heffner int mss_now; 15995d424d5aSJohn Heffner 16005d424d5aSJohn Heffner /* Not currently probing/verifying, 16015d424d5aSJohn Heffner * not in recovery, 16025d424d5aSJohn Heffner * have enough cwnd, and 16035d424d5aSJohn Heffner * not SACKing (the variable headers throw things off) */ 16045d424d5aSJohn Heffner if (!icsk->icsk_mtup.enabled || 16055d424d5aSJohn Heffner icsk->icsk_mtup.probe_size || 16065d424d5aSJohn Heffner inet_csk(sk)->icsk_ca_state != TCP_CA_Open || 16075d424d5aSJohn Heffner tp->snd_cwnd < 11 || 1608cabeccbdSIlpo Järvinen tp->rx_opt.num_sacks || tp->rx_opt.dsack) 16095d424d5aSJohn Heffner return -1; 16105d424d5aSJohn Heffner 16115d424d5aSJohn Heffner /* Very simple search strategy: just double the MSS. */ 16120c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 16135d424d5aSJohn Heffner probe_size = 2 * tp->mss_cache; 161491cc17c0SIlpo Järvinen size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; 16155d424d5aSJohn Heffner if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { 16165d424d5aSJohn Heffner /* TODO: set timer for probe_converge_event */ 16175d424d5aSJohn Heffner return -1; 16185d424d5aSJohn Heffner } 16195d424d5aSJohn Heffner 16205d424d5aSJohn Heffner /* Have enough data in the send queue to probe? */ 16217f9c33e5SIlpo Järvinen if (tp->write_seq - tp->snd_nxt < size_needed) 16225d424d5aSJohn Heffner return -1; 16235d424d5aSJohn Heffner 162491cc17c0SIlpo Järvinen if (tp->snd_wnd < size_needed) 16255d424d5aSJohn Heffner return -1; 162690840defSIlpo Järvinen if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) 16275d424d5aSJohn Heffner return 0; 16285d424d5aSJohn Heffner 1629d67c58e9SIlpo Järvinen /* Do we need to wait to drain cwnd? With none in flight, don't stall */ 1630d67c58e9SIlpo Järvinen if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { 1631d67c58e9SIlpo Järvinen if (!tcp_packets_in_flight(tp)) 16325d424d5aSJohn Heffner return -1; 16335d424d5aSJohn Heffner else 16345d424d5aSJohn Heffner return 0; 16355d424d5aSJohn Heffner } 16365d424d5aSJohn Heffner 16375d424d5aSJohn Heffner /* We're allowed to probe. Build it now. */ 16385d424d5aSJohn Heffner if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL) 16395d424d5aSJohn Heffner return -1; 16403ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 16413ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 16425d424d5aSJohn Heffner 1643fe067e8aSDavid S. Miller skb = tcp_send_head(sk); 16445d424d5aSJohn Heffner 16455d424d5aSJohn Heffner TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; 16465d424d5aSJohn Heffner TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; 16475d424d5aSJohn Heffner TCP_SKB_CB(nskb)->flags = TCPCB_FLAG_ACK; 16485d424d5aSJohn Heffner TCP_SKB_CB(nskb)->sacked = 0; 16495d424d5aSJohn Heffner nskb->csum = 0; 165084fa7933SPatrick McHardy nskb->ip_summed = skb->ip_summed; 16515d424d5aSJohn Heffner 165250c4817eSIlpo Järvinen tcp_insert_write_queue_before(nskb, skb, sk); 165350c4817eSIlpo Järvinen 16545d424d5aSJohn Heffner len = 0; 1655234b6860SIlpo Järvinen tcp_for_write_queue_from_safe(skb, next, sk) { 16565d424d5aSJohn Heffner copy = min_t(int, skb->len, probe_size - len); 16575d424d5aSJohn Heffner if (nskb->ip_summed) 16585d424d5aSJohn Heffner skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); 16595d424d5aSJohn Heffner else 16605d424d5aSJohn Heffner nskb->csum = skb_copy_and_csum_bits(skb, 0, 1661056834d9SIlpo Järvinen skb_put(nskb, copy), 1662056834d9SIlpo Järvinen copy, nskb->csum); 16635d424d5aSJohn Heffner 16645d424d5aSJohn Heffner if (skb->len <= copy) { 16655d424d5aSJohn Heffner /* We've eaten all the data from this skb. 16665d424d5aSJohn Heffner * Throw it away. */ 16675d424d5aSJohn Heffner TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags; 1668fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 16693ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 16705d424d5aSJohn Heffner } else { 16715d424d5aSJohn Heffner TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags & 16725d424d5aSJohn Heffner ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); 16735d424d5aSJohn Heffner if (!skb_shinfo(skb)->nr_frags) { 16745d424d5aSJohn Heffner skb_pull(skb, copy); 167584fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 1676056834d9SIlpo Järvinen skb->csum = csum_partial(skb->data, 1677056834d9SIlpo Järvinen skb->len, 0); 16785d424d5aSJohn Heffner } else { 16795d424d5aSJohn Heffner __pskb_trim_head(skb, copy); 16805d424d5aSJohn Heffner tcp_set_skb_tso_segs(sk, skb, mss_now); 16815d424d5aSJohn Heffner } 16825d424d5aSJohn Heffner TCP_SKB_CB(skb)->seq += copy; 16835d424d5aSJohn Heffner } 16845d424d5aSJohn Heffner 16855d424d5aSJohn Heffner len += copy; 1686234b6860SIlpo Järvinen 1687234b6860SIlpo Järvinen if (len >= probe_size) 1688234b6860SIlpo Järvinen break; 16895d424d5aSJohn Heffner } 16905d424d5aSJohn Heffner tcp_init_tso_segs(sk, nskb, nskb->len); 16915d424d5aSJohn Heffner 16925d424d5aSJohn Heffner /* We're ready to send. If this fails, the probe will 16935d424d5aSJohn Heffner * be resegmented into mss-sized pieces by tcp_write_xmit(). */ 16945d424d5aSJohn Heffner TCP_SKB_CB(nskb)->when = tcp_time_stamp; 16955d424d5aSJohn Heffner if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { 16965d424d5aSJohn Heffner /* Decrement cwnd here because we are sending 16975d424d5aSJohn Heffner * effectively two packets. */ 16985d424d5aSJohn Heffner tp->snd_cwnd--; 169966f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, nskb); 17005d424d5aSJohn Heffner 17015d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); 17020e7b1368SJohn Heffner tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; 17030e7b1368SJohn Heffner tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; 17045d424d5aSJohn Heffner 17055d424d5aSJohn Heffner return 1; 17065d424d5aSJohn Heffner } 17075d424d5aSJohn Heffner 17085d424d5aSJohn Heffner return -1; 17095d424d5aSJohn Heffner } 17105d424d5aSJohn Heffner 17111da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 17121da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 17131da177e4SLinus Torvalds * window for us. 17141da177e4SLinus Torvalds * 1715f8269a49SIlpo Järvinen * LARGESEND note: !tcp_urg_mode is overkill, only frames between 1716f8269a49SIlpo Järvinen * snd_up-64k-mss .. snd_up cannot be large. However, taking into 1717f8269a49SIlpo Järvinen * account rare use of URG, this is not a big flaw. 1718f8269a49SIlpo Järvinen * 17191da177e4SLinus Torvalds * Returns 1, if no segments are in flight and we have queued segments, but 17201da177e4SLinus Torvalds * cannot send anything now because of SWS or another problem. 17211da177e4SLinus Torvalds */ 1722d5dd9175SIlpo Järvinen static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 1723d5dd9175SIlpo Järvinen int push_one, gfp_t gfp) 17241da177e4SLinus Torvalds { 17251da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 172692df7b51SDavid S. Miller struct sk_buff *skb; 1727c1b4a7e6SDavid S. Miller unsigned int tso_segs, sent_pkts; 1728c1b4a7e6SDavid S. Miller int cwnd_quota; 17295d424d5aSJohn Heffner int result; 17301da177e4SLinus Torvalds 1731c1b4a7e6SDavid S. Miller sent_pkts = 0; 17325d424d5aSJohn Heffner 1733d5dd9175SIlpo Järvinen if (!push_one) { 17345d424d5aSJohn Heffner /* Do MTU probing. */ 1735d5dd9175SIlpo Järvinen result = tcp_mtu_probe(sk); 1736d5dd9175SIlpo Järvinen if (!result) { 17375d424d5aSJohn Heffner return 0; 17385d424d5aSJohn Heffner } else if (result > 0) { 17395d424d5aSJohn Heffner sent_pkts = 1; 17405d424d5aSJohn Heffner } 1741d5dd9175SIlpo Järvinen } 17425d424d5aSJohn Heffner 1743fe067e8aSDavid S. Miller while ((skb = tcp_send_head(sk))) { 1744c8ac3774SHerbert Xu unsigned int limit; 1745c8ac3774SHerbert Xu 1746b68e9f85SHerbert Xu tso_segs = tcp_init_tso_segs(sk, skb, mss_now); 1747c1b4a7e6SDavid S. Miller BUG_ON(!tso_segs); 1748c1b4a7e6SDavid S. Miller 1749b68e9f85SHerbert Xu cwnd_quota = tcp_cwnd_test(tp, skb); 1750b68e9f85SHerbert Xu if (!cwnd_quota) 1751b68e9f85SHerbert Xu break; 1752b68e9f85SHerbert Xu 1753b68e9f85SHerbert Xu if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) 1754b68e9f85SHerbert Xu break; 1755b68e9f85SHerbert Xu 1756c1b4a7e6SDavid S. Miller if (tso_segs == 1) { 1757aa93466bSDavid S. Miller if (unlikely(!tcp_nagle_test(tp, skb, mss_now, 1758aa93466bSDavid S. Miller (tcp_skb_is_last(sk, skb) ? 1759aa93466bSDavid S. Miller nonagle : TCP_NAGLE_PUSH)))) 1760aa93466bSDavid S. Miller break; 1761c1b4a7e6SDavid S. Miller } else { 1762d5dd9175SIlpo Järvinen if (!push_one && tcp_tso_should_defer(sk, skb)) 1763aa93466bSDavid S. Miller break; 1764c1b4a7e6SDavid S. Miller } 1765aa93466bSDavid S. Miller 1766c8ac3774SHerbert Xu limit = mss_now; 1767f8269a49SIlpo Järvinen if (tso_segs > 1 && !tcp_urg_mode(tp)) 17680e3a4803SIlpo Järvinen limit = tcp_mss_split_point(sk, skb, mss_now, 17690e3a4803SIlpo Järvinen cwnd_quota); 1770c8ac3774SHerbert Xu 1771c8ac3774SHerbert Xu if (skb->len > limit && 1772c8ac3774SHerbert Xu unlikely(tso_fragment(sk, skb, limit, mss_now))) 17731da177e4SLinus Torvalds break; 17741da177e4SLinus Torvalds 17751da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 1776c1b4a7e6SDavid S. Miller 1777d5dd9175SIlpo Järvinen if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) 17781da177e4SLinus Torvalds break; 17791da177e4SLinus Torvalds 17801da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 17811da177e4SLinus Torvalds * This call will increment packets_out. 17821da177e4SLinus Torvalds */ 178366f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 17841da177e4SLinus Torvalds 17851da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 1786aa93466bSDavid S. Miller sent_pkts++; 1787d5dd9175SIlpo Järvinen 1788d5dd9175SIlpo Järvinen if (push_one) 1789d5dd9175SIlpo Järvinen break; 17901da177e4SLinus Torvalds } 17911da177e4SLinus Torvalds 1792aa93466bSDavid S. Miller if (likely(sent_pkts)) { 17939e412ba7SIlpo Järvinen tcp_cwnd_validate(sk); 17941da177e4SLinus Torvalds return 0; 17951da177e4SLinus Torvalds } 1796fe067e8aSDavid S. Miller return !tp->packets_out && tcp_send_head(sk); 17971da177e4SLinus Torvalds } 17981da177e4SLinus Torvalds 1799a762a980SDavid S. Miller /* Push out any pending frames which were held back due to 1800a762a980SDavid S. Miller * TCP_CORK or attempt at coalescing tiny packets. 1801a762a980SDavid S. Miller * The socket must be locked by the caller. 1802a762a980SDavid S. Miller */ 18039e412ba7SIlpo Järvinen void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 18049e412ba7SIlpo Järvinen int nonagle) 1805a762a980SDavid S. Miller { 1806726e07a8SIlpo Järvinen /* If we are closed, the bytes will have to remain here. 1807726e07a8SIlpo Järvinen * In time closedown will finish, we empty the write queue and 1808726e07a8SIlpo Järvinen * all will be happy. 1809726e07a8SIlpo Järvinen */ 1810726e07a8SIlpo Järvinen if (unlikely(sk->sk_state == TCP_CLOSE)) 1811726e07a8SIlpo Järvinen return; 1812726e07a8SIlpo Järvinen 1813d5dd9175SIlpo Järvinen if (tcp_write_xmit(sk, cur_mss, nonagle, 0, GFP_ATOMIC)) 18149e412ba7SIlpo Järvinen tcp_check_probe_timer(sk); 1815a762a980SDavid S. Miller } 1816a762a980SDavid S. Miller 1817c1b4a7e6SDavid S. Miller /* Send _single_ skb sitting at the send head. This function requires 1818c1b4a7e6SDavid S. Miller * true push pending frames to setup probe timer etc. 1819c1b4a7e6SDavid S. Miller */ 1820c1b4a7e6SDavid S. Miller void tcp_push_one(struct sock *sk, unsigned int mss_now) 1821c1b4a7e6SDavid S. Miller { 1822fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_send_head(sk); 1823c1b4a7e6SDavid S. Miller 1824c1b4a7e6SDavid S. Miller BUG_ON(!skb || skb->len < mss_now); 1825c1b4a7e6SDavid S. Miller 1826d5dd9175SIlpo Järvinen tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); 1827c1b4a7e6SDavid S. Miller } 1828c1b4a7e6SDavid S. Miller 18291da177e4SLinus Torvalds /* This function returns the amount that we can raise the 18301da177e4SLinus Torvalds * usable window based on the following constraints 18311da177e4SLinus Torvalds * 18321da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 18331da177e4SLinus Torvalds * 2. We limit memory per socket 18341da177e4SLinus Torvalds * 18351da177e4SLinus Torvalds * RFC 1122: 18361da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 18371da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 18381da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 18391da177e4SLinus Torvalds * 18401da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 18411da177e4SLinus Torvalds * it at least MSS bytes. 18421da177e4SLinus Torvalds * 18431da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 18441da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 18451da177e4SLinus Torvalds * 18461da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 18471da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 18481da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 18491da177e4SLinus Torvalds * window to always advance by a single byte. 18501da177e4SLinus Torvalds * 18511da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 18521da177e4SLinus Torvalds * then this will not be a problem. 18531da177e4SLinus Torvalds * 18541da177e4SLinus Torvalds * BSD seems to make the following compromise: 18551da177e4SLinus Torvalds * 18561da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 18571da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 18581da177e4SLinus Torvalds * then set the window to 0. 18591da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 18601da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 18611da177e4SLinus Torvalds * and from being larger than the largest representable value. 18621da177e4SLinus Torvalds * 18631da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 18641da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 18651da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 18661da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 18671da177e4SLinus Torvalds * because the pipeline is full. 18681da177e4SLinus Torvalds * 18691da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 18701da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 18711da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 18721da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 18731da177e4SLinus Torvalds * of having a fixed window size at almost all times. 18741da177e4SLinus Torvalds * 18751da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 18761da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 18771da177e4SLinus Torvalds * 18781da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 18791da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 18801da177e4SLinus Torvalds */ 18811da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 18821da177e4SLinus Torvalds { 1883463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 18841da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1885caa20d9aSStephen Hemminger /* MSS for the peer's data. Previous versions used mss_clamp 18861da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 18871da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 18881da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 18891da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 18901da177e4SLinus Torvalds */ 1891463c84b9SArnaldo Carvalho de Melo int mss = icsk->icsk_ack.rcv_mss; 18921da177e4SLinus Torvalds int free_space = tcp_space(sk); 18931da177e4SLinus Torvalds int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); 18941da177e4SLinus Torvalds int window; 18951da177e4SLinus Torvalds 18961da177e4SLinus Torvalds if (mss > full_space) 18971da177e4SLinus Torvalds mss = full_space; 18981da177e4SLinus Torvalds 1899b92edbe0SEric Dumazet if (free_space < (full_space >> 1)) { 1900463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.quick = 0; 19011da177e4SLinus Torvalds 19021da177e4SLinus Torvalds if (tcp_memory_pressure) 1903056834d9SIlpo Järvinen tp->rcv_ssthresh = min(tp->rcv_ssthresh, 1904056834d9SIlpo Järvinen 4U * tp->advmss); 19051da177e4SLinus Torvalds 19061da177e4SLinus Torvalds if (free_space < mss) 19071da177e4SLinus Torvalds return 0; 19081da177e4SLinus Torvalds } 19091da177e4SLinus Torvalds 19101da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 19111da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 19121da177e4SLinus Torvalds 19131da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 19141da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 19151da177e4SLinus Torvalds */ 19161da177e4SLinus Torvalds window = tp->rcv_wnd; 19171da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 19181da177e4SLinus Torvalds window = free_space; 19191da177e4SLinus Torvalds 19201da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 19211da177e4SLinus Torvalds * Import case: prevent zero window announcement if 19221da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 19231da177e4SLinus Torvalds */ 19241da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 19251da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 19261da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 19271da177e4SLinus Torvalds } else { 19281da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 19291da177e4SLinus Torvalds * Window clamp already applied above. 19301da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 19311da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 19321da177e4SLinus Torvalds * and multiply from happening most of the time. 19331da177e4SLinus Torvalds * We also don't do any window rounding when the free space 19341da177e4SLinus Torvalds * is too small. 19351da177e4SLinus Torvalds */ 19361da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 19371da177e4SLinus Torvalds window = (free_space / mss) * mss; 193884565070SJohn Heffner else if (mss == full_space && 1939b92edbe0SEric Dumazet free_space > window + (full_space >> 1)) 194084565070SJohn Heffner window = free_space; 19411da177e4SLinus Torvalds } 19421da177e4SLinus Torvalds 19431da177e4SLinus Torvalds return window; 19441da177e4SLinus Torvalds } 19451da177e4SLinus Torvalds 19464a17fc3aSIlpo Järvinen /* Collapses two adjacent SKB's during retransmission. */ 19474a17fc3aSIlpo Järvinen static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) 19481da177e4SLinus Torvalds { 19491da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1950fe067e8aSDavid S. Miller struct sk_buff *next_skb = tcp_write_queue_next(sk, skb); 1951058dc334SIlpo Järvinen int skb_size, next_skb_size; 19521da177e4SLinus Torvalds 1953058dc334SIlpo Järvinen skb_size = skb->len; 1954058dc334SIlpo Järvinen next_skb_size = next_skb->len; 19551da177e4SLinus Torvalds 1956058dc334SIlpo Järvinen BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); 19571da177e4SLinus Torvalds 19586859d494SIlpo Järvinen tcp_highest_sack_combine(sk, next_skb, skb); 1959a6963a6bSIlpo Järvinen 1960fe067e8aSDavid S. Miller tcp_unlink_write_queue(next_skb, sk); 19611da177e4SLinus Torvalds 1962058dc334SIlpo Järvinen skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size), 19631a4e2d09SArnaldo Carvalho de Melo next_skb_size); 19641da177e4SLinus Torvalds 196552d570aaSJarek Poplawski if (next_skb->ip_summed == CHECKSUM_PARTIAL) 196652d570aaSJarek Poplawski skb->ip_summed = CHECKSUM_PARTIAL; 19671da177e4SLinus Torvalds 196884fa7933SPatrick McHardy if (skb->ip_summed != CHECKSUM_PARTIAL) 19691da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 19701da177e4SLinus Torvalds 19711da177e4SLinus Torvalds /* Update sequence range on original skb. */ 19721da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 19731da177e4SLinus Torvalds 1974e6c7d085SIlpo Järvinen /* Merge over control information. This moves PSH/FIN etc. over */ 1975e6c7d085SIlpo Järvinen TCP_SKB_CB(skb)->flags |= TCP_SKB_CB(next_skb)->flags; 19761da177e4SLinus Torvalds 19771da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 19781da177e4SLinus Torvalds * packet counting does not break. 19791da177e4SLinus Torvalds */ 19804828e7f4SIlpo Järvinen TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; 1981b7689205SIlpo Järvinen 1982b7689205SIlpo Järvinen /* changed transmit queue under us so clear hints */ 1983ef9da47cSIlpo Järvinen tcp_clear_retrans_hints_partial(tp); 1984ef9da47cSIlpo Järvinen if (next_skb == tp->retransmit_skb_hint) 1985ef9da47cSIlpo Järvinen tp->retransmit_skb_hint = skb; 1986b7689205SIlpo Järvinen 1987797108d1SIlpo Järvinen tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); 1988797108d1SIlpo Järvinen 19893ab224beSHideo Aoki sk_wmem_free_skb(sk, next_skb); 19901da177e4SLinus Torvalds } 19911da177e4SLinus Torvalds 199267edfef7SAndi Kleen /* Check if coalescing SKBs is legal. */ 19934a17fc3aSIlpo Järvinen static int tcp_can_collapse(struct sock *sk, struct sk_buff *skb) 19944a17fc3aSIlpo Järvinen { 19954a17fc3aSIlpo Järvinen if (tcp_skb_pcount(skb) > 1) 19964a17fc3aSIlpo Järvinen return 0; 19974a17fc3aSIlpo Järvinen /* TODO: SACK collapsing could be used to remove this condition */ 19984a17fc3aSIlpo Järvinen if (skb_shinfo(skb)->nr_frags != 0) 19994a17fc3aSIlpo Järvinen return 0; 20004a17fc3aSIlpo Järvinen if (skb_cloned(skb)) 20014a17fc3aSIlpo Järvinen return 0; 20024a17fc3aSIlpo Järvinen if (skb == tcp_send_head(sk)) 20034a17fc3aSIlpo Järvinen return 0; 20044a17fc3aSIlpo Järvinen /* Some heurestics for collapsing over SACK'd could be invented */ 20054a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) 20064a17fc3aSIlpo Järvinen return 0; 20074a17fc3aSIlpo Järvinen 20084a17fc3aSIlpo Järvinen return 1; 20094a17fc3aSIlpo Järvinen } 20104a17fc3aSIlpo Järvinen 201167edfef7SAndi Kleen /* Collapse packets in the retransmit queue to make to create 201267edfef7SAndi Kleen * less packets on the wire. This is only done on retransmission. 201367edfef7SAndi Kleen */ 20144a17fc3aSIlpo Järvinen static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, 20154a17fc3aSIlpo Järvinen int space) 20164a17fc3aSIlpo Järvinen { 20174a17fc3aSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 20184a17fc3aSIlpo Järvinen struct sk_buff *skb = to, *tmp; 20194a17fc3aSIlpo Järvinen int first = 1; 20204a17fc3aSIlpo Järvinen 20214a17fc3aSIlpo Järvinen if (!sysctl_tcp_retrans_collapse) 20224a17fc3aSIlpo Järvinen return; 20234a17fc3aSIlpo Järvinen if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN) 20244a17fc3aSIlpo Järvinen return; 20254a17fc3aSIlpo Järvinen 20264a17fc3aSIlpo Järvinen tcp_for_write_queue_from_safe(skb, tmp, sk) { 20274a17fc3aSIlpo Järvinen if (!tcp_can_collapse(sk, skb)) 20284a17fc3aSIlpo Järvinen break; 20294a17fc3aSIlpo Järvinen 20304a17fc3aSIlpo Järvinen space -= skb->len; 20314a17fc3aSIlpo Järvinen 20324a17fc3aSIlpo Järvinen if (first) { 20334a17fc3aSIlpo Järvinen first = 0; 20344a17fc3aSIlpo Järvinen continue; 20354a17fc3aSIlpo Järvinen } 20364a17fc3aSIlpo Järvinen 20374a17fc3aSIlpo Järvinen if (space < 0) 20384a17fc3aSIlpo Järvinen break; 20394a17fc3aSIlpo Järvinen /* Punt if not enough space exists in the first SKB for 20404a17fc3aSIlpo Järvinen * the data in the second 20414a17fc3aSIlpo Järvinen */ 20424a17fc3aSIlpo Järvinen if (skb->len > skb_tailroom(to)) 20434a17fc3aSIlpo Järvinen break; 20444a17fc3aSIlpo Järvinen 20454a17fc3aSIlpo Järvinen if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) 20464a17fc3aSIlpo Järvinen break; 20474a17fc3aSIlpo Järvinen 20484a17fc3aSIlpo Järvinen tcp_collapse_retrans(sk, to); 20494a17fc3aSIlpo Järvinen } 20504a17fc3aSIlpo Järvinen } 20514a17fc3aSIlpo Järvinen 20521da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 20531da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 20541da177e4SLinus Torvalds * error occurred which prevented the send. 20551da177e4SLinus Torvalds */ 20561da177e4SLinus Torvalds int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 20571da177e4SLinus Torvalds { 20581da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 20595d424d5aSJohn Heffner struct inet_connection_sock *icsk = inet_csk(sk); 20607d227cd2SSridhar Samudrala unsigned int cur_mss; 20611da177e4SLinus Torvalds int err; 20621da177e4SLinus Torvalds 20635d424d5aSJohn Heffner /* Inconslusive MTU probe */ 20645d424d5aSJohn Heffner if (icsk->icsk_mtup.probe_size) { 20655d424d5aSJohn Heffner icsk->icsk_mtup.probe_size = 0; 20665d424d5aSJohn Heffner } 20675d424d5aSJohn Heffner 20681da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 2069caa20d9aSStephen Hemminger * copying overhead: fragmentation, tunneling, mangling etc. 20701da177e4SLinus Torvalds */ 20711da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 20721da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 20731da177e4SLinus Torvalds return -EAGAIN; 20741da177e4SLinus Torvalds 20751da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 20761da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 20771da177e4SLinus Torvalds BUG(); 20781da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 20791da177e4SLinus Torvalds return -ENOMEM; 20801da177e4SLinus Torvalds } 20811da177e4SLinus Torvalds 20827d227cd2SSridhar Samudrala if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) 20837d227cd2SSridhar Samudrala return -EHOSTUNREACH; /* Routing failure or similar. */ 20847d227cd2SSridhar Samudrala 20850c54b85fSIlpo Järvinen cur_mss = tcp_current_mss(sk); 20867d227cd2SSridhar Samudrala 20871da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 20881da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 20891da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 20901da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 20911da177e4SLinus Torvalds */ 20929d4fb27dSJoe Perches if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && 20939d4fb27dSJoe Perches TCP_SKB_CB(skb)->seq != tp->snd_una) 20941da177e4SLinus Torvalds return -EAGAIN; 20951da177e4SLinus Torvalds 20961da177e4SLinus Torvalds if (skb->len > cur_mss) { 2097846998aeSDavid S. Miller if (tcp_fragment(sk, skb, cur_mss, cur_mss)) 20981da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 209902276f3cSIlpo Järvinen } else { 21009eb9362eSIlpo Järvinen int oldpcount = tcp_skb_pcount(skb); 21019eb9362eSIlpo Järvinen 21029eb9362eSIlpo Järvinen if (unlikely(oldpcount > 1)) { 210302276f3cSIlpo Järvinen tcp_init_tso_segs(sk, skb, cur_mss); 21049eb9362eSIlpo Järvinen tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); 21059eb9362eSIlpo Järvinen } 21061da177e4SLinus Torvalds } 21071da177e4SLinus Torvalds 21081da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 21091da177e4SLinus Torvalds 21101da177e4SLinus Torvalds /* Some Solaris stacks overoptimize and ignore the FIN on a 21111da177e4SLinus Torvalds * retransmit when old data is attached. So strip it off 21121da177e4SLinus Torvalds * since it is cheap to do so and saves bytes on the network. 21131da177e4SLinus Torvalds */ 21141da177e4SLinus Torvalds if (skb->len > 0 && 21151da177e4SLinus Torvalds (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && 21161da177e4SLinus Torvalds tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { 21171da177e4SLinus Torvalds if (!pskb_trim(skb, 0)) { 2118e870a8efSIlpo Järvinen /* Reuse, even though it does some unnecessary work */ 2119e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1, 2120e870a8efSIlpo Järvinen TCP_SKB_CB(skb)->flags); 21211da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 21221da177e4SLinus Torvalds } 21231da177e4SLinus Torvalds } 21241da177e4SLinus Torvalds 21251da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 21261da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 21271da177e4SLinus Torvalds */ 21281da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 21291da177e4SLinus Torvalds 2130dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 21311da177e4SLinus Torvalds 21321da177e4SLinus Torvalds if (err == 0) { 21331da177e4SLinus Torvalds /* Update global TCP statistics. */ 213481cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); 21351da177e4SLinus Torvalds 21361da177e4SLinus Torvalds tp->total_retrans++; 21371da177e4SLinus Torvalds 21381da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 21391da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { 21401da177e4SLinus Torvalds if (net_ratelimit()) 21411da177e4SLinus Torvalds printk(KERN_DEBUG "retrans_out leaked.\n"); 21421da177e4SLinus Torvalds } 21431da177e4SLinus Torvalds #endif 2144b08d6cb2SIlpo Järvinen if (!tp->retrans_out) 2145b08d6cb2SIlpo Järvinen tp->lost_retrans_low = tp->snd_nxt; 21461da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 21471da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 21481da177e4SLinus Torvalds 21491da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 21501da177e4SLinus Torvalds if (!tp->retrans_stamp) 21511da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(skb)->when; 21521da177e4SLinus Torvalds 21531da177e4SLinus Torvalds tp->undo_retrans++; 21541da177e4SLinus Torvalds 21551da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 21561da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 21571da177e4SLinus Torvalds */ 21581da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 21591da177e4SLinus Torvalds } 21601da177e4SLinus Torvalds return err; 21611da177e4SLinus Torvalds } 21621da177e4SLinus Torvalds 216367edfef7SAndi Kleen /* Check if we forward retransmits are possible in the current 216467edfef7SAndi Kleen * window/congestion state. 216567edfef7SAndi Kleen */ 2166b5afe7bcSIlpo Järvinen static int tcp_can_forward_retransmit(struct sock *sk) 2167b5afe7bcSIlpo Järvinen { 2168b5afe7bcSIlpo Järvinen const struct inet_connection_sock *icsk = inet_csk(sk); 2169b5afe7bcSIlpo Järvinen struct tcp_sock *tp = tcp_sk(sk); 2170b5afe7bcSIlpo Järvinen 2171b5afe7bcSIlpo Järvinen /* Forward retransmissions are possible only during Recovery. */ 2172b5afe7bcSIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Recovery) 2173b5afe7bcSIlpo Järvinen return 0; 2174b5afe7bcSIlpo Järvinen 2175b5afe7bcSIlpo Järvinen /* No forward retransmissions in Reno are possible. */ 2176b5afe7bcSIlpo Järvinen if (tcp_is_reno(tp)) 2177b5afe7bcSIlpo Järvinen return 0; 2178b5afe7bcSIlpo Järvinen 2179b5afe7bcSIlpo Järvinen /* Yeah, we have to make difficult choice between forward transmission 2180b5afe7bcSIlpo Järvinen * and retransmission... Both ways have their merits... 2181b5afe7bcSIlpo Järvinen * 2182b5afe7bcSIlpo Järvinen * For now we do not retransmit anything, while we have some new 2183b5afe7bcSIlpo Järvinen * segments to send. In the other cases, follow rule 3 for 2184b5afe7bcSIlpo Järvinen * NextSeg() specified in RFC3517. 2185b5afe7bcSIlpo Järvinen */ 2186b5afe7bcSIlpo Järvinen 2187b5afe7bcSIlpo Järvinen if (tcp_may_send_now(sk)) 2188b5afe7bcSIlpo Järvinen return 0; 2189b5afe7bcSIlpo Järvinen 2190b5afe7bcSIlpo Järvinen return 1; 2191b5afe7bcSIlpo Järvinen } 2192b5afe7bcSIlpo Järvinen 21931da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 21941da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 21951da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 21961da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 21971da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 21981da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 21991da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 22001da177e4SLinus Torvalds */ 22011da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 22021da177e4SLinus Torvalds { 22036687e988SArnaldo Carvalho de Melo const struct inet_connection_sock *icsk = inet_csk(sk); 22041da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 22051da177e4SLinus Torvalds struct sk_buff *skb; 22060e1c54c2SIlpo Järvinen struct sk_buff *hole = NULL; 2207618d9f25SIlpo Järvinen u32 last_lost; 220861eb55f4SIlpo Järvinen int mib_idx; 22090e1c54c2SIlpo Järvinen int fwd_rexmitting = 0; 22106a438bbeSStephen Hemminger 221108ebd172SIlpo Järvinen if (!tp->lost_out) 221208ebd172SIlpo Järvinen tp->retransmit_high = tp->snd_una; 221308ebd172SIlpo Järvinen 2214618d9f25SIlpo Järvinen if (tp->retransmit_skb_hint) { 22156a438bbeSStephen Hemminger skb = tp->retransmit_skb_hint; 2216618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 2217618d9f25SIlpo Järvinen if (after(last_lost, tp->retransmit_high)) 2218618d9f25SIlpo Järvinen last_lost = tp->retransmit_high; 2219618d9f25SIlpo Järvinen } else { 2220fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 2221618d9f25SIlpo Järvinen last_lost = tp->snd_una; 2222618d9f25SIlpo Järvinen } 22231da177e4SLinus Torvalds 2224fe067e8aSDavid S. Miller tcp_for_write_queue_from(skb, sk) { 22251da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 22261da177e4SLinus Torvalds 2227fe067e8aSDavid S. Miller if (skb == tcp_send_head(sk)) 2228fe067e8aSDavid S. Miller break; 22296a438bbeSStephen Hemminger /* we could do better than to assign each time */ 22300e1c54c2SIlpo Järvinen if (hole == NULL) 22316a438bbeSStephen Hemminger tp->retransmit_skb_hint = skb; 22326a438bbeSStephen Hemminger 22331da177e4SLinus Torvalds /* Assume this retransmit will generate 22341da177e4SLinus Torvalds * only one packet for congestion window 22351da177e4SLinus Torvalds * calculation purposes. This works because 22361da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 22371da177e4SLinus Torvalds * packet to be MSS sized and all the 22381da177e4SLinus Torvalds * packet counting works out. 22391da177e4SLinus Torvalds */ 22401da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 22411da177e4SLinus Torvalds return; 22420e1c54c2SIlpo Järvinen 22430e1c54c2SIlpo Järvinen if (fwd_rexmitting) { 22440e1c54c2SIlpo Järvinen begin_fwd: 22450e1c54c2SIlpo Järvinen if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp))) 2246006f582cSIlpo Järvinen break; 22470e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFORWARDRETRANS; 22480e1c54c2SIlpo Järvinen 22490e1c54c2SIlpo Järvinen } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { 2250618d9f25SIlpo Järvinen tp->retransmit_high = last_lost; 22510e1c54c2SIlpo Järvinen if (!tcp_can_forward_retransmit(sk)) 22520e1c54c2SIlpo Järvinen break; 22530e1c54c2SIlpo Järvinen /* Backtrack if necessary to non-L'ed skb */ 22540e1c54c2SIlpo Järvinen if (hole != NULL) { 22550e1c54c2SIlpo Järvinen skb = hole; 22560e1c54c2SIlpo Järvinen hole = NULL; 22570e1c54c2SIlpo Järvinen } 22580e1c54c2SIlpo Järvinen fwd_rexmitting = 1; 22590e1c54c2SIlpo Järvinen goto begin_fwd; 22600e1c54c2SIlpo Järvinen 22610e1c54c2SIlpo Järvinen } else if (!(sacked & TCPCB_LOST)) { 2262ac11ba75SIlpo Järvinen if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) 22630e1c54c2SIlpo Järvinen hole = skb; 226461eb55f4SIlpo Järvinen continue; 22651da177e4SLinus Torvalds 22660e1c54c2SIlpo Järvinen } else { 2267618d9f25SIlpo Järvinen last_lost = TCP_SKB_CB(skb)->end_seq; 22680e1c54c2SIlpo Järvinen if (icsk->icsk_ca_state != TCP_CA_Loss) 22690e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPFASTRETRANS; 22700e1c54c2SIlpo Järvinen else 22710e1c54c2SIlpo Järvinen mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; 22720e1c54c2SIlpo Järvinen } 22730e1c54c2SIlpo Järvinen 22740e1c54c2SIlpo Järvinen if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) 227561eb55f4SIlpo Järvinen continue; 227640b215e5SPavel Emelyanov 2277f0ceb0edSIlpo Järvinen if (tcp_retransmit_skb(sk, skb)) 22781da177e4SLinus Torvalds return; 2279de0744afSPavel Emelyanov NET_INC_STATS_BH(sock_net(sk), mib_idx); 22801da177e4SLinus Torvalds 2281fe067e8aSDavid S. Miller if (skb == tcp_write_queue_head(sk)) 2282463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 22833f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, 22843f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 22851da177e4SLinus Torvalds } 22861da177e4SLinus Torvalds } 22871da177e4SLinus Torvalds 22881da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 22891da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 22901da177e4SLinus Torvalds */ 22911da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 22921da177e4SLinus Torvalds { 22931da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2294fe067e8aSDavid S. Miller struct sk_buff *skb = tcp_write_queue_tail(sk); 22951da177e4SLinus Torvalds int mss_now; 22961da177e4SLinus Torvalds 22971da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 22981da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 22991da177e4SLinus Torvalds * and IP options. 23001da177e4SLinus Torvalds */ 23010c54b85fSIlpo Järvinen mss_now = tcp_current_mss(sk); 23021da177e4SLinus Torvalds 2303fe067e8aSDavid S. Miller if (tcp_send_head(sk) != NULL) { 23041da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; 23051da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 23061da177e4SLinus Torvalds tp->write_seq++; 23071da177e4SLinus Torvalds } else { 23081da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 23091da177e4SLinus Torvalds for (;;) { 2310aa133076SWu Fengguang skb = alloc_skb_fclone(MAX_TCP_HEADER, 2311aa133076SWu Fengguang sk->sk_allocation); 23121da177e4SLinus Torvalds if (skb) 23131da177e4SLinus Torvalds break; 23141da177e4SLinus Torvalds yield(); 23151da177e4SLinus Torvalds } 23161da177e4SLinus Torvalds 23171da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 23181da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 23191da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 2320e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->write_seq, 2321e870a8efSIlpo Järvinen TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); 23221da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 23231da177e4SLinus Torvalds } 23249e412ba7SIlpo Järvinen __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF); 23251da177e4SLinus Torvalds } 23261da177e4SLinus Torvalds 23271da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 23281da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 23291da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 233065bb723cSGerrit Renker * by RFC 2525, section 2.17. -DaveM 23311da177e4SLinus Torvalds */ 2332dd0fc66fSAl Viro void tcp_send_active_reset(struct sock *sk, gfp_t priority) 23331da177e4SLinus Torvalds { 23341da177e4SLinus Torvalds struct sk_buff *skb; 23351da177e4SLinus Torvalds 23361da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 23371da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 23381da177e4SLinus Torvalds if (!skb) { 23394e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 23401da177e4SLinus Torvalds return; 23411da177e4SLinus Torvalds } 23421da177e4SLinus Torvalds 23431da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 23441da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 2345e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), 2346e870a8efSIlpo Järvinen TCPCB_FLAG_ACK | TCPCB_FLAG_RST); 23471da177e4SLinus Torvalds /* Send it off. */ 23481da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2349dfb4b9dcSDavid S. Miller if (tcp_transmit_skb(sk, skb, 0, priority)) 23504e673444SPavel Emelyanov NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); 235126af65cbSSridhar Samudrala 235281cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); 23531da177e4SLinus Torvalds } 23541da177e4SLinus Torvalds 235567edfef7SAndi Kleen /* Send a crossed SYN-ACK during socket establishment. 235667edfef7SAndi Kleen * WARNING: This routine must only be called when we have already sent 23571da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 23581da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 23591da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 23601da177e4SLinus Torvalds */ 23611da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 23621da177e4SLinus Torvalds { 23631da177e4SLinus Torvalds struct sk_buff *skb; 23641da177e4SLinus Torvalds 2365fe067e8aSDavid S. Miller skb = tcp_write_queue_head(sk); 23661da177e4SLinus Torvalds if (skb == NULL || !(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN)) { 23671da177e4SLinus Torvalds printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); 23681da177e4SLinus Torvalds return -EFAULT; 23691da177e4SLinus Torvalds } 23701da177e4SLinus Torvalds if (!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_ACK)) { 23711da177e4SLinus Torvalds if (skb_cloned(skb)) { 23721da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 23731da177e4SLinus Torvalds if (nskb == NULL) 23741da177e4SLinus Torvalds return -ENOMEM; 2375fe067e8aSDavid S. Miller tcp_unlink_write_queue(skb, sk); 23761da177e4SLinus Torvalds skb_header_release(nskb); 2377fe067e8aSDavid S. Miller __tcp_add_write_queue_head(sk, nskb); 23783ab224beSHideo Aoki sk_wmem_free_skb(sk, skb); 23793ab224beSHideo Aoki sk->sk_wmem_queued += nskb->truesize; 23803ab224beSHideo Aoki sk_mem_charge(sk, nskb->truesize); 23811da177e4SLinus Torvalds skb = nskb; 23821da177e4SLinus Torvalds } 23831da177e4SLinus Torvalds 23841da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ACK; 23851da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 23861da177e4SLinus Torvalds } 23871da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2388dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 23891da177e4SLinus Torvalds } 23901da177e4SLinus Torvalds 239167edfef7SAndi Kleen /* Prepare a SYN-ACK. */ 23921da177e4SLinus Torvalds struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, 2393e6b4d113SWilliam Allen Simpson struct request_sock *req, 2394e6b4d113SWilliam Allen Simpson struct request_values *rvp) 23951da177e4SLinus Torvalds { 2396bd0388aeSWilliam Allen Simpson struct tcp_out_options opts; 23974957faadSWilliam Allen Simpson struct tcp_extend_values *xvp = tcp_xv(rvp); 23982e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 23991da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 240028b2774aSEric Dumazet const struct tcp_cookie_values *cvp = tp->cookie_values; 24011da177e4SLinus Torvalds struct tcphdr *th; 24021da177e4SLinus Torvalds struct sk_buff *skb; 2403cfb6eeb4SYOSHIFUJI Hideaki struct tcp_md5sig_key *md5; 2404bd0388aeSWilliam Allen Simpson int tcp_header_size; 2405f5fff5dcSTom Quetchenbach int mss; 240628b2774aSEric Dumazet int s_data_desired = 0; 24071da177e4SLinus Torvalds 240828b2774aSEric Dumazet if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired) 240928b2774aSEric Dumazet s_data_desired = cvp->s_data_desired; 241028b2774aSEric Dumazet skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1, GFP_ATOMIC); 24111da177e4SLinus Torvalds if (skb == NULL) 24121da177e4SLinus Torvalds return NULL; 24131da177e4SLinus Torvalds 24141da177e4SLinus Torvalds /* Reserve space for headers. */ 24151da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 24161da177e4SLinus Torvalds 2417adf30907SEric Dumazet skb_dst_set(skb, dst_clone(dst)); 24181da177e4SLinus Torvalds 2419f5fff5dcSTom Quetchenbach mss = dst_metric(dst, RTAX_ADVMSS); 2420f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) 2421f5fff5dcSTom Quetchenbach mss = tp->rx_opt.user_mss; 2422f5fff5dcSTom Quetchenbach 242333ad798cSAdam Langley if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ 242433ad798cSAdam Langley __u8 rcv_wscale; 242533ad798cSAdam Langley /* Set this up on the first call only */ 242633ad798cSAdam Langley req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); 242733ad798cSAdam Langley /* tcp_full_space because it is guaranteed to be the first packet */ 242833ad798cSAdam Langley tcp_select_initial_window(tcp_full_space(sk), 2429f5fff5dcSTom Quetchenbach mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), 243033ad798cSAdam Langley &req->rcv_wnd, 243133ad798cSAdam Langley &req->window_clamp, 243233ad798cSAdam Langley ireq->wscale_ok, 243331d12926Slaurent chavey &rcv_wscale, 243431d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 243533ad798cSAdam Langley ireq->rcv_wscale = rcv_wscale; 243633ad798cSAdam Langley } 2437cfb6eeb4SYOSHIFUJI Hideaki 243833ad798cSAdam Langley memset(&opts, 0, sizeof(opts)); 24398b5f12d0SFlorian Westphal #ifdef CONFIG_SYN_COOKIES 24408b5f12d0SFlorian Westphal if (unlikely(req->cookie_ts)) 24418b5f12d0SFlorian Westphal TCP_SKB_CB(skb)->when = cookie_init_timestamp(req); 24428b5f12d0SFlorian Westphal else 24438b5f12d0SFlorian Westphal #endif 244433ad798cSAdam Langley TCP_SKB_CB(skb)->when = tcp_time_stamp; 2445f5fff5dcSTom Quetchenbach tcp_header_size = tcp_synack_options(sk, req, mss, 24464957faadSWilliam Allen Simpson skb, &opts, &md5, xvp) 24474957faadSWilliam Allen Simpson + sizeof(*th); 244833ad798cSAdam Langley 2449aa8223c7SArnaldo Carvalho de Melo skb_push(skb, tcp_header_size); 2450aa8223c7SArnaldo Carvalho de Melo skb_reset_transport_header(skb); 24511da177e4SLinus Torvalds 2452aa8223c7SArnaldo Carvalho de Melo th = tcp_hdr(skb); 24531da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 24541da177e4SLinus Torvalds th->syn = 1; 24551da177e4SLinus Torvalds th->ack = 1; 24561da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 2457a3116ac5SKOVACS Krisztian th->source = ireq->loc_port; 24582e6599cbSArnaldo Carvalho de Melo th->dest = ireq->rmt_port; 2459e870a8efSIlpo Järvinen /* Setting of flags are superfluous here for callers (and ECE is 2460e870a8efSIlpo Järvinen * not even correctly set) 2461e870a8efSIlpo Järvinen */ 2462e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn, 2463e870a8efSIlpo Järvinen TCPCB_FLAG_SYN | TCPCB_FLAG_ACK); 24644957faadSWilliam Allen Simpson 24654957faadSWilliam Allen Simpson if (OPTION_COOKIE_EXTENSION & opts.options) { 246628b2774aSEric Dumazet if (s_data_desired) { 246728b2774aSEric Dumazet u8 *buf = skb_put(skb, s_data_desired); 24684957faadSWilliam Allen Simpson 24694957faadSWilliam Allen Simpson /* copy data directly from the listening socket. */ 247028b2774aSEric Dumazet memcpy(buf, cvp->s_data_payload, s_data_desired); 247128b2774aSEric Dumazet TCP_SKB_CB(skb)->end_seq += s_data_desired; 24724957faadSWilliam Allen Simpson } 24734957faadSWilliam Allen Simpson 24744957faadSWilliam Allen Simpson if (opts.hash_size > 0) { 24754957faadSWilliam Allen Simpson __u32 workspace[SHA_WORKSPACE_WORDS]; 24764957faadSWilliam Allen Simpson u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS]; 24774957faadSWilliam Allen Simpson u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1]; 24784957faadSWilliam Allen Simpson 24794957faadSWilliam Allen Simpson /* Secret recipe depends on the Timestamp, (future) 24804957faadSWilliam Allen Simpson * Sequence and Acknowledgment Numbers, Initiator 24814957faadSWilliam Allen Simpson * Cookie, and others handled by IP variant caller. 24824957faadSWilliam Allen Simpson */ 24834957faadSWilliam Allen Simpson *tail-- ^= opts.tsval; 24844957faadSWilliam Allen Simpson *tail-- ^= tcp_rsk(req)->rcv_isn + 1; 24854957faadSWilliam Allen Simpson *tail-- ^= TCP_SKB_CB(skb)->seq + 1; 24864957faadSWilliam Allen Simpson 24874957faadSWilliam Allen Simpson /* recommended */ 24884957faadSWilliam Allen Simpson *tail-- ^= ((th->dest << 16) | th->source); 2489f9a2e69eSDavid S. Miller *tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */ 24904957faadSWilliam Allen Simpson 24914957faadSWilliam Allen Simpson sha_transform((__u32 *)&xvp->cookie_bakery[0], 24924957faadSWilliam Allen Simpson (char *)mess, 24934957faadSWilliam Allen Simpson &workspace[0]); 24944957faadSWilliam Allen Simpson opts.hash_location = 24954957faadSWilliam Allen Simpson (__u8 *)&xvp->cookie_bakery[0]; 24964957faadSWilliam Allen Simpson } 24974957faadSWilliam Allen Simpson } 24984957faadSWilliam Allen Simpson 24991da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 25002e6599cbSArnaldo Carvalho de Melo th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); 25011da177e4SLinus Torvalds 25021da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 2503600ff0c2SIlpo Järvinen th->window = htons(min(req->rcv_wnd, 65535U)); 2504bd0388aeSWilliam Allen Simpson tcp_options_write((__be32 *)(th + 1), tp, &opts); 25051da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 250681cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); 2507cfb6eeb4SYOSHIFUJI Hideaki 2508cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2509cfb6eeb4SYOSHIFUJI Hideaki /* Okay, we have all we need - do the md5 hash if needed */ 2510cfb6eeb4SYOSHIFUJI Hideaki if (md5) { 2511bd0388aeSWilliam Allen Simpson tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, 251249a72dfbSAdam Langley md5, NULL, req, skb); 2513cfb6eeb4SYOSHIFUJI Hideaki } 2514cfb6eeb4SYOSHIFUJI Hideaki #endif 2515cfb6eeb4SYOSHIFUJI Hideaki 25161da177e4SLinus Torvalds return skb; 25171da177e4SLinus Torvalds } 25181da177e4SLinus Torvalds 251967edfef7SAndi Kleen /* Do all connect socket setups that can be done AF independent. */ 252040efc6faSStephen Hemminger static void tcp_connect_init(struct sock *sk) 25211da177e4SLinus Torvalds { 25221da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 25231da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 25241da177e4SLinus Torvalds __u8 rcv_wscale; 25251da177e4SLinus Torvalds 25261da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 25271da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 25281da177e4SLinus Torvalds */ 25291da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 2530bb5b7c11SDavid S. Miller (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 25311da177e4SLinus Torvalds 2532cfb6eeb4SYOSHIFUJI Hideaki #ifdef CONFIG_TCP_MD5SIG 2533cfb6eeb4SYOSHIFUJI Hideaki if (tp->af_specific->md5_lookup(sk, sk) != NULL) 2534cfb6eeb4SYOSHIFUJI Hideaki tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; 2535cfb6eeb4SYOSHIFUJI Hideaki #endif 2536cfb6eeb4SYOSHIFUJI Hideaki 25371da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 25381da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 25391da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 25401da177e4SLinus Torvalds tp->max_window = 0; 25415d424d5aSJohn Heffner tcp_mtup_init(sk); 25421da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 25431da177e4SLinus Torvalds 25441da177e4SLinus Torvalds if (!tp->window_clamp) 25451da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 25461da177e4SLinus Torvalds tp->advmss = dst_metric(dst, RTAX_ADVMSS); 2547f5fff5dcSTom Quetchenbach if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss) 2548f5fff5dcSTom Quetchenbach tp->advmss = tp->rx_opt.user_mss; 2549f5fff5dcSTom Quetchenbach 25501da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 25511da177e4SLinus Torvalds 25521da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 25531da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 25541da177e4SLinus Torvalds &tp->rcv_wnd, 25551da177e4SLinus Torvalds &tp->window_clamp, 2556bb5b7c11SDavid S. Miller sysctl_tcp_window_scaling, 255731d12926Slaurent chavey &rcv_wscale, 255831d12926Slaurent chavey dst_metric(dst, RTAX_INITRWND)); 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 25611da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 25621da177e4SLinus Torvalds 25631da177e4SLinus Torvalds sk->sk_err = 0; 25641da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 25651da177e4SLinus Torvalds tp->snd_wnd = 0; 2566ee7537b6SHantzis Fotis tcp_init_wl(tp, 0); 25671da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 25681da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 256933f5f57eSIlpo Järvinen tp->snd_up = tp->write_seq; 25701da177e4SLinus Torvalds tp->rcv_nxt = 0; 25711da177e4SLinus Torvalds tp->rcv_wup = 0; 25721da177e4SLinus Torvalds tp->copied_seq = 0; 25731da177e4SLinus Torvalds 2574463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; 2575463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_retransmits = 0; 25761da177e4SLinus Torvalds tcp_clear_retrans(tp); 25771da177e4SLinus Torvalds } 25781da177e4SLinus Torvalds 257967edfef7SAndi Kleen /* Build a SYN and send it off. */ 25801da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 25811da177e4SLinus Torvalds { 25821da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 25831da177e4SLinus Torvalds struct sk_buff *buff; 25841da177e4SLinus Torvalds 25851da177e4SLinus Torvalds tcp_connect_init(sk); 25861da177e4SLinus Torvalds 2587d179cd12SDavid S. Miller buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); 25881da177e4SLinus Torvalds if (unlikely(buff == NULL)) 25891da177e4SLinus Torvalds return -ENOBUFS; 25901da177e4SLinus Torvalds 25911da177e4SLinus Torvalds /* Reserve space for headers. */ 25921da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 25931da177e4SLinus Torvalds 2594bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 2595e870a8efSIlpo Järvinen tcp_init_nondata_skb(buff, tp->write_seq++, TCPCB_FLAG_SYN); 2596e870a8efSIlpo Järvinen TCP_ECN_send_syn(sk, buff); 25971da177e4SLinus Torvalds 25981da177e4SLinus Torvalds /* Send it off. */ 25991da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 26001da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(buff)->when; 26011da177e4SLinus Torvalds skb_header_release(buff); 2602fe067e8aSDavid S. Miller __tcp_add_write_queue_tail(sk, buff); 26033ab224beSHideo Aoki sk->sk_wmem_queued += buff->truesize; 26043ab224beSHideo Aoki sk_mem_charge(sk, buff->truesize); 26051da177e4SLinus Torvalds tp->packets_out += tcp_skb_pcount(buff); 2606aa133076SWu Fengguang tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); 2607bd37a088SWei Yongjun 2608bd37a088SWei Yongjun /* We change tp->snd_nxt after the tcp_transmit_skb() call 2609bd37a088SWei Yongjun * in order to make this packet get counted in tcpOutSegs. 2610bd37a088SWei Yongjun */ 2611bd37a088SWei Yongjun tp->snd_nxt = tp->write_seq; 2612bd37a088SWei Yongjun tp->pushed_seq = tp->write_seq; 261381cc8a75SPavel Emelyanov TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); 26141da177e4SLinus Torvalds 26151da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 26163f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 26173f421baaSArnaldo Carvalho de Melo inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 26181da177e4SLinus Torvalds return 0; 26191da177e4SLinus Torvalds } 26201da177e4SLinus Torvalds 26211da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 26221da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 26231da177e4SLinus Torvalds * for details. 26241da177e4SLinus Torvalds */ 26251da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 26261da177e4SLinus Torvalds { 2627463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 2628463c84b9SArnaldo Carvalho de Melo int ato = icsk->icsk_ack.ato; 26291da177e4SLinus Torvalds unsigned long timeout; 26301da177e4SLinus Torvalds 26311da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 2632463c84b9SArnaldo Carvalho de Melo const struct tcp_sock *tp = tcp_sk(sk); 26331da177e4SLinus Torvalds int max_ato = HZ / 2; 26341da177e4SLinus Torvalds 2635056834d9SIlpo Järvinen if (icsk->icsk_ack.pingpong || 2636056834d9SIlpo Järvinen (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) 26371da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 26381da177e4SLinus Torvalds 26391da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 26401da177e4SLinus Torvalds 26411da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 2642463c84b9SArnaldo Carvalho de Melo * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements 26431da177e4SLinus Torvalds * directly. 26441da177e4SLinus Torvalds */ 26451da177e4SLinus Torvalds if (tp->srtt) { 26461da177e4SLinus Torvalds int rtt = max(tp->srtt >> 3, TCP_DELACK_MIN); 26471da177e4SLinus Torvalds 26481da177e4SLinus Torvalds if (rtt < max_ato) 26491da177e4SLinus Torvalds max_ato = rtt; 26501da177e4SLinus Torvalds } 26511da177e4SLinus Torvalds 26521da177e4SLinus Torvalds ato = min(ato, max_ato); 26531da177e4SLinus Torvalds } 26541da177e4SLinus Torvalds 26551da177e4SLinus Torvalds /* Stay within the limit we were given */ 26561da177e4SLinus Torvalds timeout = jiffies + ato; 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 2659463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { 26601da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 26611da177e4SLinus Torvalds * send ACK now. 26621da177e4SLinus Torvalds */ 2663463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_ack.blocked || 2664463c84b9SArnaldo Carvalho de Melo time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { 26651da177e4SLinus Torvalds tcp_send_ack(sk); 26661da177e4SLinus Torvalds return; 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds 2669463c84b9SArnaldo Carvalho de Melo if (!time_before(timeout, icsk->icsk_ack.timeout)) 2670463c84b9SArnaldo Carvalho de Melo timeout = icsk->icsk_ack.timeout; 26711da177e4SLinus Torvalds } 2672463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; 2673463c84b9SArnaldo Carvalho de Melo icsk->icsk_ack.timeout = timeout; 2674463c84b9SArnaldo Carvalho de Melo sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); 26751da177e4SLinus Torvalds } 26761da177e4SLinus Torvalds 26771da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 26781da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 26791da177e4SLinus Torvalds { 26801da177e4SLinus Torvalds struct sk_buff *buff; 26811da177e4SLinus Torvalds 2682058dc334SIlpo Järvinen /* If we have been reset, we may not send again. */ 2683058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 2684058dc334SIlpo Järvinen return; 2685058dc334SIlpo Järvinen 26861da177e4SLinus Torvalds /* We are not putting this on the write queue, so 26871da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 26881da177e4SLinus Torvalds * sock. 26891da177e4SLinus Torvalds */ 26901da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 26911da177e4SLinus Torvalds if (buff == NULL) { 2692463c84b9SArnaldo Carvalho de Melo inet_csk_schedule_ack(sk); 2693463c84b9SArnaldo Carvalho de Melo inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; 26943f421baaSArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 26953f421baaSArnaldo Carvalho de Melo TCP_DELACK_MAX, TCP_RTO_MAX); 26961da177e4SLinus Torvalds return; 26971da177e4SLinus Torvalds } 26981da177e4SLinus Torvalds 26991da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 27001da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 2701e870a8efSIlpo Järvinen tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPCB_FLAG_ACK); 27021da177e4SLinus Torvalds 27031da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 27041da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 2705dfb4b9dcSDavid S. Miller tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC); 27061da177e4SLinus Torvalds } 27071da177e4SLinus Torvalds 27081da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 27091da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 27101da177e4SLinus Torvalds * 27111da177e4SLinus Torvalds * Question: what should we make while urgent mode? 27121da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 27131da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 27141da177e4SLinus Torvalds * 27151da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 27161da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 27171da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 27181da177e4SLinus Torvalds */ 27191da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 27201da177e4SLinus Torvalds { 27211da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27221da177e4SLinus Torvalds struct sk_buff *skb; 27231da177e4SLinus Torvalds 27241da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 27251da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 27261da177e4SLinus Torvalds if (skb == NULL) 27271da177e4SLinus Torvalds return -1; 27281da177e4SLinus Torvalds 27291da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 27301da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 27311da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 27321da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 27331da177e4SLinus Torvalds * send it. 27341da177e4SLinus Torvalds */ 2735e870a8efSIlpo Järvinen tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPCB_FLAG_ACK); 27361da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2737dfb4b9dcSDavid S. Miller return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); 27381da177e4SLinus Torvalds } 27391da177e4SLinus Torvalds 274067edfef7SAndi Kleen /* Initiate keepalive or window probe from timer. */ 27411da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 27421da177e4SLinus Torvalds { 27431da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27441da177e4SLinus Torvalds struct sk_buff *skb; 27451da177e4SLinus Torvalds 2746058dc334SIlpo Järvinen if (sk->sk_state == TCP_CLOSE) 2747058dc334SIlpo Järvinen return -1; 2748058dc334SIlpo Järvinen 2749fe067e8aSDavid S. Miller if ((skb = tcp_send_head(sk)) != NULL && 275090840defSIlpo Järvinen before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { 27511da177e4SLinus Torvalds int err; 27520c54b85fSIlpo Järvinen unsigned int mss = tcp_current_mss(sk); 275390840defSIlpo Järvinen unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; 27541da177e4SLinus Torvalds 27551da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 27561da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds /* We are probing the opening of a window 27591da177e4SLinus Torvalds * but the window size is != 0 27601da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 27611da177e4SLinus Torvalds */ 27621da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 27631da177e4SLinus Torvalds skb->len > mss) { 27641da177e4SLinus Torvalds seg_size = min(seg_size, mss); 27651da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 2766846998aeSDavid S. Miller if (tcp_fragment(sk, skb, seg_size, mss)) 27671da177e4SLinus Torvalds return -1; 27681da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 2769846998aeSDavid S. Miller tcp_set_skb_tso_segs(sk, skb, mss); 27701da177e4SLinus Torvalds 27711da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 27721da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 2773dfb4b9dcSDavid S. Miller err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); 277466f5fe62SIlpo Järvinen if (!err) 277566f5fe62SIlpo Järvinen tcp_event_new_data_sent(sk, skb); 27761da177e4SLinus Torvalds return err; 27771da177e4SLinus Torvalds } else { 277833f5f57eSIlpo Järvinen if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) 27794828e7f4SIlpo Järvinen tcp_xmit_probe_skb(sk, 1); 27801da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 27811da177e4SLinus Torvalds } 27821da177e4SLinus Torvalds } 27831da177e4SLinus Torvalds 27841da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 27851da177e4SLinus Torvalds * a partial packet else a zero probe. 27861da177e4SLinus Torvalds */ 27871da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 27881da177e4SLinus Torvalds { 2789463c84b9SArnaldo Carvalho de Melo struct inet_connection_sock *icsk = inet_csk(sk); 27901da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 27911da177e4SLinus Torvalds int err; 27921da177e4SLinus Torvalds 27931da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 27941da177e4SLinus Torvalds 2795fe067e8aSDavid S. Miller if (tp->packets_out || !tcp_send_head(sk)) { 27961da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 27976687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 0; 2798463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff = 0; 27991da177e4SLinus Torvalds return; 28001da177e4SLinus Torvalds } 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds if (err <= 0) { 2803463c84b9SArnaldo Carvalho de Melo if (icsk->icsk_backoff < sysctl_tcp_retries2) 2804463c84b9SArnaldo Carvalho de Melo icsk->icsk_backoff++; 28056687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out++; 2806463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 28073f421baaSArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), 28083f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 28091da177e4SLinus Torvalds } else { 28101da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 28116687e988SArnaldo Carvalho de Melo * do not backoff and do not remember icsk_probes_out. 28121da177e4SLinus Torvalds * Let local senders to fight for local resources. 28131da177e4SLinus Torvalds * 28141da177e4SLinus Torvalds * Use accumulated backoff yet. 28151da177e4SLinus Torvalds */ 28166687e988SArnaldo Carvalho de Melo if (!icsk->icsk_probes_out) 28176687e988SArnaldo Carvalho de Melo icsk->icsk_probes_out = 1; 2818463c84b9SArnaldo Carvalho de Melo inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 2819463c84b9SArnaldo Carvalho de Melo min(icsk->icsk_rto << icsk->icsk_backoff, 28203f421baaSArnaldo Carvalho de Melo TCP_RESOURCE_PROBE_INTERVAL), 28213f421baaSArnaldo Carvalho de Melo TCP_RTO_MAX); 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds 2825c6aefafbSGlenn Griffin EXPORT_SYMBOL(tcp_select_initial_window); 28261da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_connect); 28271da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_make_synack); 28281da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_simple_retransmit); 28291da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_sync_mss); 28305d424d5aSJohn Heffner EXPORT_SYMBOL(tcp_mtup_init); 2831