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 * 81da177e4SLinus Torvalds * Version: $Id: tcp_output.c,v 1.146 2002/02/01 22:01:04 davem Exp $ 91da177e4SLinus Torvalds * 1002c30a84SJesper Juhl * Authors: Ross Biro 111da177e4SLinus Torvalds * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 121da177e4SLinus Torvalds * Mark Evans, <evansmp@uhura.aston.ac.uk> 131da177e4SLinus Torvalds * Corey Minyard <wf-rch!minyard@relay.EU.net> 141da177e4SLinus Torvalds * Florian La Roche, <flla@stud.uni-sb.de> 151da177e4SLinus Torvalds * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 161da177e4SLinus Torvalds * Linus Torvalds, <torvalds@cs.helsinki.fi> 171da177e4SLinus Torvalds * Alan Cox, <gw4pts@gw4pts.ampr.org> 181da177e4SLinus Torvalds * Matthew Dillon, <dillon@apollo.west.oic.com> 191da177e4SLinus Torvalds * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 201da177e4SLinus Torvalds * Jorge Cwik, <jorge@laser.satlink.net> 211da177e4SLinus Torvalds */ 221da177e4SLinus Torvalds 231da177e4SLinus Torvalds /* 241da177e4SLinus Torvalds * Changes: Pedro Roque : Retransmit queue handled by TCP. 251da177e4SLinus Torvalds * : Fragmentation on mtu decrease 261da177e4SLinus Torvalds * : Segment collapse on retransmit 271da177e4SLinus Torvalds * : AF independence 281da177e4SLinus Torvalds * 291da177e4SLinus Torvalds * Linus Torvalds : send_delayed_ack 301da177e4SLinus Torvalds * David S. Miller : Charge memory using the right skb 311da177e4SLinus Torvalds * during syn/ack processing. 321da177e4SLinus Torvalds * David S. Miller : Output engine completely rewritten. 331da177e4SLinus Torvalds * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. 341da177e4SLinus Torvalds * Cacophonix Gaul : draft-minshall-nagle-01 351da177e4SLinus Torvalds * J Hadi Salim : ECN support 361da177e4SLinus Torvalds * 371da177e4SLinus Torvalds */ 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds #include <net/tcp.h> 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds #include <linux/compiler.h> 421da177e4SLinus Torvalds #include <linux/module.h> 431da177e4SLinus Torvalds #include <linux/smp_lock.h> 441da177e4SLinus Torvalds 451da177e4SLinus Torvalds /* People can turn this off for buggy TCP's found in printers etc. */ 461da177e4SLinus Torvalds int sysctl_tcp_retrans_collapse = 1; 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds /* This limits the percentage of the congestion window which we 491da177e4SLinus Torvalds * will allow a single TSO frame to consume. Building TSO frames 501da177e4SLinus Torvalds * which are too large can cause TCP streams to be bursty. 511da177e4SLinus Torvalds */ 521da177e4SLinus Torvalds int sysctl_tcp_tso_win_divisor = 8; 531da177e4SLinus Torvalds 541da177e4SLinus Torvalds static inline void update_send_head(struct sock *sk, struct tcp_sock *tp, 551da177e4SLinus Torvalds struct sk_buff *skb) 561da177e4SLinus Torvalds { 571da177e4SLinus Torvalds sk->sk_send_head = skb->next; 581da177e4SLinus Torvalds if (sk->sk_send_head == (struct sk_buff *)&sk->sk_write_queue) 591da177e4SLinus Torvalds sk->sk_send_head = NULL; 601da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 611da177e4SLinus Torvalds tcp_packets_out_inc(sk, tp, skb); 621da177e4SLinus Torvalds } 631da177e4SLinus Torvalds 641da177e4SLinus Torvalds /* SND.NXT, if window was not shrunk. 651da177e4SLinus Torvalds * If window has been shrunk, what should we make? It is not clear at all. 661da177e4SLinus Torvalds * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( 671da177e4SLinus Torvalds * Anything in between SND.UNA...SND.UNA+SND.WND also can be already 681da177e4SLinus Torvalds * invalid. OK, let's make this for now: 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds static inline __u32 tcp_acceptable_seq(struct sock *sk, struct tcp_sock *tp) 711da177e4SLinus Torvalds { 721da177e4SLinus Torvalds if (!before(tp->snd_una+tp->snd_wnd, tp->snd_nxt)) 731da177e4SLinus Torvalds return tp->snd_nxt; 741da177e4SLinus Torvalds else 751da177e4SLinus Torvalds return tp->snd_una+tp->snd_wnd; 761da177e4SLinus Torvalds } 771da177e4SLinus Torvalds 781da177e4SLinus Torvalds /* Calculate mss to advertise in SYN segment. 791da177e4SLinus Torvalds * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: 801da177e4SLinus Torvalds * 811da177e4SLinus Torvalds * 1. It is independent of path mtu. 821da177e4SLinus Torvalds * 2. Ideally, it is maximal possible segment size i.e. 65535-40. 831da177e4SLinus Torvalds * 3. For IPv4 it is reasonable to calculate it from maximal MTU of 841da177e4SLinus Torvalds * attached devices, because some buggy hosts are confused by 851da177e4SLinus Torvalds * large MSS. 861da177e4SLinus Torvalds * 4. We do not make 3, we advertise MSS, calculated from first 871da177e4SLinus Torvalds * hop device mtu, but allow to raise it to ip_rt_min_advmss. 881da177e4SLinus Torvalds * This may be overridden via information stored in routing table. 891da177e4SLinus Torvalds * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, 901da177e4SLinus Torvalds * probably even Jumbo". 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds static __u16 tcp_advertise_mss(struct sock *sk) 931da177e4SLinus Torvalds { 941da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 951da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 961da177e4SLinus Torvalds int mss = tp->advmss; 971da177e4SLinus Torvalds 981da177e4SLinus Torvalds if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { 991da177e4SLinus Torvalds mss = dst_metric(dst, RTAX_ADVMSS); 1001da177e4SLinus Torvalds tp->advmss = mss; 1011da177e4SLinus Torvalds } 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds return (__u16)mss; 1041da177e4SLinus Torvalds } 1051da177e4SLinus Torvalds 1061da177e4SLinus Torvalds /* RFC2861. Reset CWND after idle period longer RTO to "restart window". 1071da177e4SLinus Torvalds * This is the first part of cwnd validation mechanism. */ 1081da177e4SLinus Torvalds static void tcp_cwnd_restart(struct tcp_sock *tp, struct dst_entry *dst) 1091da177e4SLinus Torvalds { 1101da177e4SLinus Torvalds s32 delta = tcp_time_stamp - tp->lsndtime; 1111da177e4SLinus Torvalds u32 restart_cwnd = tcp_init_cwnd(tp, dst); 1121da177e4SLinus Torvalds u32 cwnd = tp->snd_cwnd; 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds if (tcp_is_vegas(tp)) 1151da177e4SLinus Torvalds tcp_vegas_enable(tp); 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds tp->snd_ssthresh = tcp_current_ssthresh(tp); 1181da177e4SLinus Torvalds restart_cwnd = min(restart_cwnd, cwnd); 1191da177e4SLinus Torvalds 1201da177e4SLinus Torvalds while ((delta -= tp->rto) > 0 && cwnd > restart_cwnd) 1211da177e4SLinus Torvalds cwnd >>= 1; 1221da177e4SLinus Torvalds tp->snd_cwnd = max(cwnd, restart_cwnd); 1231da177e4SLinus Torvalds tp->snd_cwnd_stamp = tcp_time_stamp; 1241da177e4SLinus Torvalds tp->snd_cwnd_used = 0; 1251da177e4SLinus Torvalds } 1261da177e4SLinus Torvalds 1271da177e4SLinus Torvalds static inline void tcp_event_data_sent(struct tcp_sock *tp, 1281da177e4SLinus Torvalds struct sk_buff *skb, struct sock *sk) 1291da177e4SLinus Torvalds { 1301da177e4SLinus Torvalds u32 now = tcp_time_stamp; 1311da177e4SLinus Torvalds 1321da177e4SLinus Torvalds if (!tp->packets_out && (s32)(now - tp->lsndtime) > tp->rto) 1331da177e4SLinus Torvalds tcp_cwnd_restart(tp, __sk_dst_get(sk)); 1341da177e4SLinus Torvalds 1351da177e4SLinus Torvalds tp->lsndtime = now; 1361da177e4SLinus Torvalds 1371da177e4SLinus Torvalds /* If it is a reply for ato after last received 1381da177e4SLinus Torvalds * packet, enter pingpong mode. 1391da177e4SLinus Torvalds */ 1401da177e4SLinus Torvalds if ((u32)(now - tp->ack.lrcvtime) < tp->ack.ato) 1411da177e4SLinus Torvalds tp->ack.pingpong = 1; 1421da177e4SLinus Torvalds } 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds static __inline__ void tcp_event_ack_sent(struct sock *sk) 1451da177e4SLinus Torvalds { 1461da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds tcp_dec_quickack_mode(tp); 1491da177e4SLinus Torvalds tcp_clear_xmit_timer(sk, TCP_TIME_DACK); 1501da177e4SLinus Torvalds } 1511da177e4SLinus Torvalds 1521da177e4SLinus Torvalds /* Determine a window scaling and initial window to offer. 1531da177e4SLinus Torvalds * Based on the assumption that the given amount of space 1541da177e4SLinus Torvalds * will be offered. Store the results in the tp structure. 1551da177e4SLinus Torvalds * NOTE: for smooth operation initial space offering should 1561da177e4SLinus Torvalds * be a multiple of mss if possible. We assume here that mss >= 1. 1571da177e4SLinus Torvalds * This MUST be enforced by all callers. 1581da177e4SLinus Torvalds */ 1591da177e4SLinus Torvalds void tcp_select_initial_window(int __space, __u32 mss, 1601da177e4SLinus Torvalds __u32 *rcv_wnd, __u32 *window_clamp, 1611da177e4SLinus Torvalds int wscale_ok, __u8 *rcv_wscale) 1621da177e4SLinus Torvalds { 1631da177e4SLinus Torvalds unsigned int space = (__space < 0 ? 0 : __space); 1641da177e4SLinus Torvalds 1651da177e4SLinus Torvalds /* If no clamp set the clamp to the max possible scaled window */ 1661da177e4SLinus Torvalds if (*window_clamp == 0) 1671da177e4SLinus Torvalds (*window_clamp) = (65535 << 14); 1681da177e4SLinus Torvalds space = min(*window_clamp, space); 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds /* Quantize space offering to a multiple of mss if possible. */ 1711da177e4SLinus Torvalds if (space > mss) 1721da177e4SLinus Torvalds space = (space / mss) * mss; 1731da177e4SLinus Torvalds 1741da177e4SLinus Torvalds /* NOTE: offering an initial window larger than 32767 1751da177e4SLinus Torvalds * will break some buggy TCP stacks. We try to be nice. 1761da177e4SLinus Torvalds * If we are not window scaling, then this truncates 1771da177e4SLinus Torvalds * our initial window offering to 32k. There should also 1781da177e4SLinus Torvalds * be a sysctl option to stop being nice. 1791da177e4SLinus Torvalds */ 1801da177e4SLinus Torvalds (*rcv_wnd) = min(space, MAX_TCP_WINDOW); 1811da177e4SLinus Torvalds (*rcv_wscale) = 0; 1821da177e4SLinus Torvalds if (wscale_ok) { 1831da177e4SLinus Torvalds /* Set window scaling on max possible window 1841da177e4SLinus Torvalds * See RFC1323 for an explanation of the limit to 14 1851da177e4SLinus Torvalds */ 1861da177e4SLinus Torvalds space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); 1871da177e4SLinus Torvalds while (space > 65535 && (*rcv_wscale) < 14) { 1881da177e4SLinus Torvalds space >>= 1; 1891da177e4SLinus Torvalds (*rcv_wscale)++; 1901da177e4SLinus Torvalds } 1911da177e4SLinus Torvalds } 1921da177e4SLinus Torvalds 1931da177e4SLinus Torvalds /* Set initial window to value enough for senders, 1941da177e4SLinus Torvalds * following RFC1414. Senders, not following this RFC, 1951da177e4SLinus Torvalds * will be satisfied with 2. 1961da177e4SLinus Torvalds */ 1971da177e4SLinus Torvalds if (mss > (1<<*rcv_wscale)) { 1981da177e4SLinus Torvalds int init_cwnd = 4; 1991da177e4SLinus Torvalds if (mss > 1460*3) 2001da177e4SLinus Torvalds init_cwnd = 2; 2011da177e4SLinus Torvalds else if (mss > 1460) 2021da177e4SLinus Torvalds init_cwnd = 3; 2031da177e4SLinus Torvalds if (*rcv_wnd > init_cwnd*mss) 2041da177e4SLinus Torvalds *rcv_wnd = init_cwnd*mss; 2051da177e4SLinus Torvalds } 2061da177e4SLinus Torvalds 2071da177e4SLinus Torvalds /* Set the clamp no higher than max representable value */ 2081da177e4SLinus Torvalds (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); 2091da177e4SLinus Torvalds } 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds /* Chose a new window to advertise, update state in tcp_sock for the 2121da177e4SLinus Torvalds * socket, and return result with RFC1323 scaling applied. The return 2131da177e4SLinus Torvalds * value can be stuffed directly into th->window for an outgoing 2141da177e4SLinus Torvalds * frame. 2151da177e4SLinus Torvalds */ 2161da177e4SLinus Torvalds static __inline__ u16 tcp_select_window(struct sock *sk) 2171da177e4SLinus Torvalds { 2181da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2191da177e4SLinus Torvalds u32 cur_win = tcp_receive_window(tp); 2201da177e4SLinus Torvalds u32 new_win = __tcp_select_window(sk); 2211da177e4SLinus Torvalds 2221da177e4SLinus Torvalds /* Never shrink the offered window */ 2231da177e4SLinus Torvalds if(new_win < cur_win) { 2241da177e4SLinus Torvalds /* Danger Will Robinson! 2251da177e4SLinus Torvalds * Don't update rcv_wup/rcv_wnd here or else 2261da177e4SLinus Torvalds * we will not be able to advertise a zero 2271da177e4SLinus Torvalds * window in time. --DaveM 2281da177e4SLinus Torvalds * 2291da177e4SLinus Torvalds * Relax Will Robinson. 2301da177e4SLinus Torvalds */ 2311da177e4SLinus Torvalds new_win = cur_win; 2321da177e4SLinus Torvalds } 2331da177e4SLinus Torvalds tp->rcv_wnd = new_win; 2341da177e4SLinus Torvalds tp->rcv_wup = tp->rcv_nxt; 2351da177e4SLinus Torvalds 2361da177e4SLinus Torvalds /* Make sure we do not exceed the maximum possible 2371da177e4SLinus Torvalds * scaled window. 2381da177e4SLinus Torvalds */ 2391da177e4SLinus Torvalds if (!tp->rx_opt.rcv_wscale) 2401da177e4SLinus Torvalds new_win = min(new_win, MAX_TCP_WINDOW); 2411da177e4SLinus Torvalds else 2421da177e4SLinus Torvalds new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); 2431da177e4SLinus Torvalds 2441da177e4SLinus Torvalds /* RFC1323 scaling applied */ 2451da177e4SLinus Torvalds new_win >>= tp->rx_opt.rcv_wscale; 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds /* If we advertise zero window, disable fast path. */ 2481da177e4SLinus Torvalds if (new_win == 0) 2491da177e4SLinus Torvalds tp->pred_flags = 0; 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds return new_win; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 2541da177e4SLinus Torvalds 2551da177e4SLinus Torvalds /* This routine actually transmits TCP packets queued in by 2561da177e4SLinus Torvalds * tcp_do_sendmsg(). This is used by both the initial 2571da177e4SLinus Torvalds * transmission and possible later retransmissions. 2581da177e4SLinus Torvalds * All SKB's seen here are completely headerless. It is our 2591da177e4SLinus Torvalds * job to build the TCP header, and pass the packet down to 2601da177e4SLinus Torvalds * IP so it can do the same plus pass the packet off to the 2611da177e4SLinus Torvalds * device. 2621da177e4SLinus Torvalds * 2631da177e4SLinus Torvalds * We are working here with either a clone of the original 2641da177e4SLinus Torvalds * SKB, or a fresh unique copy made by the retransmit engine. 2651da177e4SLinus Torvalds */ 2661da177e4SLinus Torvalds static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb) 2671da177e4SLinus Torvalds { 2681da177e4SLinus Torvalds if (skb != NULL) { 2691da177e4SLinus Torvalds struct inet_sock *inet = inet_sk(sk); 2701da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 2711da177e4SLinus Torvalds struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 2721da177e4SLinus Torvalds int tcp_header_size = tp->tcp_header_len; 2731da177e4SLinus Torvalds struct tcphdr *th; 2741da177e4SLinus Torvalds int sysctl_flags; 2751da177e4SLinus Torvalds int err; 2761da177e4SLinus Torvalds 2771da177e4SLinus Torvalds BUG_ON(!tcp_skb_pcount(skb)); 2781da177e4SLinus Torvalds 2791da177e4SLinus Torvalds #define SYSCTL_FLAG_TSTAMPS 0x1 2801da177e4SLinus Torvalds #define SYSCTL_FLAG_WSCALE 0x2 2811da177e4SLinus Torvalds #define SYSCTL_FLAG_SACK 0x4 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds sysctl_flags = 0; 2841da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_SYN) { 2851da177e4SLinus Torvalds tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS; 2861da177e4SLinus Torvalds if(sysctl_tcp_timestamps) { 2871da177e4SLinus Torvalds tcp_header_size += TCPOLEN_TSTAMP_ALIGNED; 2881da177e4SLinus Torvalds sysctl_flags |= SYSCTL_FLAG_TSTAMPS; 2891da177e4SLinus Torvalds } 2901da177e4SLinus Torvalds if(sysctl_tcp_window_scaling) { 2911da177e4SLinus Torvalds tcp_header_size += TCPOLEN_WSCALE_ALIGNED; 2921da177e4SLinus Torvalds sysctl_flags |= SYSCTL_FLAG_WSCALE; 2931da177e4SLinus Torvalds } 2941da177e4SLinus Torvalds if(sysctl_tcp_sack) { 2951da177e4SLinus Torvalds sysctl_flags |= SYSCTL_FLAG_SACK; 2961da177e4SLinus Torvalds if(!(sysctl_flags & SYSCTL_FLAG_TSTAMPS)) 2971da177e4SLinus Torvalds tcp_header_size += TCPOLEN_SACKPERM_ALIGNED; 2981da177e4SLinus Torvalds } 2991da177e4SLinus Torvalds } else if (tp->rx_opt.eff_sacks) { 3001da177e4SLinus Torvalds /* A SACK is 2 pad bytes, a 2 byte header, plus 3011da177e4SLinus Torvalds * 2 32-bit sequence numbers for each SACK block. 3021da177e4SLinus Torvalds */ 3031da177e4SLinus Torvalds tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED + 3041da177e4SLinus Torvalds (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); 3051da177e4SLinus Torvalds } 3061da177e4SLinus Torvalds 3071da177e4SLinus Torvalds /* 3081da177e4SLinus Torvalds * If the connection is idle and we are restarting, 3091da177e4SLinus Torvalds * then we don't want to do any Vegas calculations 3101da177e4SLinus Torvalds * until we get fresh RTT samples. So when we 3111da177e4SLinus Torvalds * restart, we reset our Vegas state to a clean 3121da177e4SLinus Torvalds * slate. After we get acks for this flight of 3131da177e4SLinus Torvalds * packets, _then_ we can make Vegas calculations 3141da177e4SLinus Torvalds * again. 3151da177e4SLinus Torvalds */ 3161da177e4SLinus Torvalds if (tcp_is_vegas(tp) && tcp_packets_in_flight(tp) == 0) 3171da177e4SLinus Torvalds tcp_vegas_enable(tp); 3181da177e4SLinus Torvalds 3191da177e4SLinus Torvalds th = (struct tcphdr *) skb_push(skb, tcp_header_size); 3201da177e4SLinus Torvalds skb->h.th = th; 3211da177e4SLinus Torvalds skb_set_owner_w(skb, sk); 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds /* Build TCP header and checksum it. */ 3241da177e4SLinus Torvalds th->source = inet->sport; 3251da177e4SLinus Torvalds th->dest = inet->dport; 3261da177e4SLinus Torvalds th->seq = htonl(tcb->seq); 3271da177e4SLinus Torvalds th->ack_seq = htonl(tp->rcv_nxt); 3281da177e4SLinus Torvalds *(((__u16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | tcb->flags); 3291da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_SYN) { 3301da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments 3311da177e4SLinus Torvalds * is never scaled. 3321da177e4SLinus Torvalds */ 3331da177e4SLinus Torvalds th->window = htons(tp->rcv_wnd); 3341da177e4SLinus Torvalds } else { 3351da177e4SLinus Torvalds th->window = htons(tcp_select_window(sk)); 3361da177e4SLinus Torvalds } 3371da177e4SLinus Torvalds th->check = 0; 3381da177e4SLinus Torvalds th->urg_ptr = 0; 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds if (tp->urg_mode && 3411da177e4SLinus Torvalds between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF)) { 3421da177e4SLinus Torvalds th->urg_ptr = htons(tp->snd_up-tcb->seq); 3431da177e4SLinus Torvalds th->urg = 1; 3441da177e4SLinus Torvalds } 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_SYN) { 3471da177e4SLinus Torvalds tcp_syn_build_options((__u32 *)(th + 1), 3481da177e4SLinus Torvalds tcp_advertise_mss(sk), 3491da177e4SLinus Torvalds (sysctl_flags & SYSCTL_FLAG_TSTAMPS), 3501da177e4SLinus Torvalds (sysctl_flags & SYSCTL_FLAG_SACK), 3511da177e4SLinus Torvalds (sysctl_flags & SYSCTL_FLAG_WSCALE), 3521da177e4SLinus Torvalds tp->rx_opt.rcv_wscale, 3531da177e4SLinus Torvalds tcb->when, 3541da177e4SLinus Torvalds tp->rx_opt.ts_recent); 3551da177e4SLinus Torvalds } else { 3561da177e4SLinus Torvalds tcp_build_and_update_options((__u32 *)(th + 1), 3571da177e4SLinus Torvalds tp, tcb->when); 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds TCP_ECN_send(sk, tp, skb, tcp_header_size); 3601da177e4SLinus Torvalds } 3611da177e4SLinus Torvalds tp->af_specific->send_check(sk, th, skb->len, skb); 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds if (tcb->flags & TCPCB_FLAG_ACK) 3641da177e4SLinus Torvalds tcp_event_ack_sent(sk); 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds if (skb->len != tcp_header_size) 3671da177e4SLinus Torvalds tcp_event_data_sent(tp, skb, sk); 3681da177e4SLinus Torvalds 3691da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_OUTSEGS); 3701da177e4SLinus Torvalds 3711da177e4SLinus Torvalds err = tp->af_specific->queue_xmit(skb, 0); 3721da177e4SLinus Torvalds if (err <= 0) 3731da177e4SLinus Torvalds return err; 3741da177e4SLinus Torvalds 3751da177e4SLinus Torvalds tcp_enter_cwr(tp); 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds /* NET_XMIT_CN is special. It does not guarantee, 3781da177e4SLinus Torvalds * that this packet is lost. It tells that device 3791da177e4SLinus Torvalds * is about to start to drop packets or already 3801da177e4SLinus Torvalds * drops some packets of the same priority and 3811da177e4SLinus Torvalds * invokes us to send less aggressively. 3821da177e4SLinus Torvalds */ 3831da177e4SLinus Torvalds return err == NET_XMIT_CN ? 0 : err; 3841da177e4SLinus Torvalds } 3851da177e4SLinus Torvalds return -ENOBUFS; 3861da177e4SLinus Torvalds #undef SYSCTL_FLAG_TSTAMPS 3871da177e4SLinus Torvalds #undef SYSCTL_FLAG_WSCALE 3881da177e4SLinus Torvalds #undef SYSCTL_FLAG_SACK 3891da177e4SLinus Torvalds } 3901da177e4SLinus Torvalds 3911da177e4SLinus Torvalds 3921da177e4SLinus Torvalds /* This routine just queue's the buffer 3931da177e4SLinus Torvalds * 3941da177e4SLinus Torvalds * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, 3951da177e4SLinus Torvalds * otherwise socket can stall. 3961da177e4SLinus Torvalds */ 3971da177e4SLinus Torvalds static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) 3981da177e4SLinus Torvalds { 3991da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 4001da177e4SLinus Torvalds 4011da177e4SLinus Torvalds /* Advance write_seq and place onto the write_queue. */ 4021da177e4SLinus Torvalds tp->write_seq = TCP_SKB_CB(skb)->end_seq; 4031da177e4SLinus Torvalds skb_header_release(skb); 4041da177e4SLinus Torvalds __skb_queue_tail(&sk->sk_write_queue, skb); 4051da177e4SLinus Torvalds sk_charge_skb(sk, skb); 4061da177e4SLinus Torvalds 4071da177e4SLinus Torvalds /* Queue it, remembering where we must start sending. */ 4081da177e4SLinus Torvalds if (sk->sk_send_head == NULL) 4091da177e4SLinus Torvalds sk->sk_send_head = skb; 4101da177e4SLinus Torvalds } 4111da177e4SLinus Torvalds 4121da177e4SLinus Torvalds static inline void tcp_tso_set_push(struct sk_buff *skb) 4131da177e4SLinus Torvalds { 4141da177e4SLinus Torvalds /* Force push to be on for any TSO frames to workaround 4151da177e4SLinus Torvalds * problems with busted implementations like Mac OS-X that 4161da177e4SLinus Torvalds * hold off socket receive wakeups until push is seen. 4171da177e4SLinus Torvalds */ 4181da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 4191da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 4201da177e4SLinus Torvalds } 4211da177e4SLinus Torvalds 4221da177e4SLinus Torvalds /* Send _single_ skb sitting at the send head. This function requires 4231da177e4SLinus Torvalds * true push pending frames to setup probe timer etc. 4241da177e4SLinus Torvalds */ 4251da177e4SLinus Torvalds void tcp_push_one(struct sock *sk, unsigned cur_mss) 4261da177e4SLinus Torvalds { 4271da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 4281da177e4SLinus Torvalds struct sk_buff *skb = sk->sk_send_head; 4291da177e4SLinus Torvalds 430d5ac99a6SDavid S. Miller if (tcp_snd_test(sk, skb, cur_mss, TCP_NAGLE_PUSH)) { 4311da177e4SLinus Torvalds /* Send it out now. */ 4321da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 4331da177e4SLinus Torvalds tcp_tso_set_push(skb); 4341da177e4SLinus Torvalds if (!tcp_transmit_skb(sk, skb_clone(skb, sk->sk_allocation))) { 4351da177e4SLinus Torvalds sk->sk_send_head = NULL; 4361da177e4SLinus Torvalds tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; 4371da177e4SLinus Torvalds tcp_packets_out_inc(sk, tp, skb); 4381da177e4SLinus Torvalds return; 4391da177e4SLinus Torvalds } 4401da177e4SLinus Torvalds } 4411da177e4SLinus Torvalds } 4421da177e4SLinus Torvalds 443d5ac99a6SDavid S. Miller void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb) 4441da177e4SLinus Torvalds { 445d5ac99a6SDavid S. Miller struct tcp_sock *tp = tcp_sk(sk); 446d5ac99a6SDavid S. Miller 447d5ac99a6SDavid S. Miller if (skb->len <= tp->mss_cache_std || 448d5ac99a6SDavid S. Miller !(sk->sk_route_caps & NETIF_F_TSO)) { 4491da177e4SLinus Torvalds /* Avoid the costly divide in the normal 4501da177e4SLinus Torvalds * non-TSO case. 4511da177e4SLinus Torvalds */ 4521da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 4531da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 4541da177e4SLinus Torvalds } else { 4551da177e4SLinus Torvalds unsigned int factor; 4561da177e4SLinus Torvalds 457d5ac99a6SDavid S. Miller factor = skb->len + (tp->mss_cache_std - 1); 458d5ac99a6SDavid S. Miller factor /= tp->mss_cache_std; 4591da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = factor; 460d5ac99a6SDavid S. Miller skb_shinfo(skb)->tso_size = tp->mss_cache_std; 4611da177e4SLinus Torvalds } 4621da177e4SLinus Torvalds } 4631da177e4SLinus Torvalds 4641da177e4SLinus Torvalds /* Function to create two new TCP segments. Shrinks the given segment 4651da177e4SLinus Torvalds * to the specified size and appends a new segment with the rest of the 4661da177e4SLinus Torvalds * packet to the list. This won't be called frequently, I hope. 4671da177e4SLinus Torvalds * Remember, these are still headerless SKBs at this point. 4681da177e4SLinus Torvalds */ 4691da177e4SLinus Torvalds static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len) 4701da177e4SLinus Torvalds { 4711da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 4721da177e4SLinus Torvalds struct sk_buff *buff; 4731da177e4SLinus Torvalds int nsize; 4741da177e4SLinus Torvalds u16 flags; 4751da177e4SLinus Torvalds 4761da177e4SLinus Torvalds nsize = skb_headlen(skb) - len; 4771da177e4SLinus Torvalds if (nsize < 0) 4781da177e4SLinus Torvalds nsize = 0; 4791da177e4SLinus Torvalds 4801da177e4SLinus Torvalds if (skb_cloned(skb) && 4811da177e4SLinus Torvalds skb_is_nonlinear(skb) && 4821da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 4831da177e4SLinus Torvalds return -ENOMEM; 4841da177e4SLinus Torvalds 4851da177e4SLinus Torvalds /* Get a new skb... force flag on. */ 4861da177e4SLinus Torvalds buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); 4871da177e4SLinus Torvalds if (buff == NULL) 4881da177e4SLinus Torvalds return -ENOMEM; /* We'll just try again later. */ 4891da177e4SLinus Torvalds sk_charge_skb(sk, buff); 4901da177e4SLinus Torvalds 4911da177e4SLinus Torvalds /* Correct the sequence numbers. */ 4921da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; 4931da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; 4941da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; 4951da177e4SLinus Torvalds 4961da177e4SLinus Torvalds /* PSH and FIN should only be set in the second packet. */ 4971da177e4SLinus Torvalds flags = TCP_SKB_CB(skb)->flags; 4981da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); 4991da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = flags; 5001da177e4SLinus Torvalds TCP_SKB_CB(buff)->sacked = 5011da177e4SLinus Torvalds (TCP_SKB_CB(skb)->sacked & 5021da177e4SLinus Torvalds (TCPCB_LOST | TCPCB_EVER_RETRANS | TCPCB_AT_TAIL)); 5031da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked &= ~TCPCB_AT_TAIL; 5041da177e4SLinus Torvalds 5051da177e4SLinus Torvalds if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_HW) { 5061da177e4SLinus Torvalds /* Copy and checksum data tail into the new buffer. */ 5071da177e4SLinus Torvalds buff->csum = csum_partial_copy_nocheck(skb->data + len, skb_put(buff, nsize), 5081da177e4SLinus Torvalds nsize, 0); 5091da177e4SLinus Torvalds 5101da177e4SLinus Torvalds skb_trim(skb, len); 5111da177e4SLinus Torvalds 5121da177e4SLinus Torvalds skb->csum = csum_block_sub(skb->csum, buff->csum, len); 5131da177e4SLinus Torvalds } else { 5141da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_HW; 5151da177e4SLinus Torvalds skb_split(skb, buff, len); 5161da177e4SLinus Torvalds } 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds buff->ip_summed = skb->ip_summed; 5191da177e4SLinus Torvalds 5201da177e4SLinus Torvalds /* Looks stupid, but our code really uses when of 5211da177e4SLinus Torvalds * skbs, which it never sent before. --ANK 5221da177e4SLinus Torvalds */ 5231da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; 5241da177e4SLinus Torvalds 5251da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { 5261da177e4SLinus Torvalds tp->lost_out -= tcp_skb_pcount(skb); 5271da177e4SLinus Torvalds tp->left_out -= tcp_skb_pcount(skb); 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds /* Fix up tso_factor for both original and new SKB. */ 531d5ac99a6SDavid S. Miller tcp_set_skb_tso_segs(sk, skb); 532d5ac99a6SDavid S. Miller tcp_set_skb_tso_segs(sk, buff); 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { 5351da177e4SLinus Torvalds tp->lost_out += tcp_skb_pcount(skb); 5361da177e4SLinus Torvalds tp->left_out += tcp_skb_pcount(skb); 5371da177e4SLinus Torvalds } 5381da177e4SLinus Torvalds 5391da177e4SLinus Torvalds if (TCP_SKB_CB(buff)->sacked&TCPCB_LOST) { 5401da177e4SLinus Torvalds tp->lost_out += tcp_skb_pcount(buff); 5411da177e4SLinus Torvalds tp->left_out += tcp_skb_pcount(buff); 5421da177e4SLinus Torvalds } 5431da177e4SLinus Torvalds 5441da177e4SLinus Torvalds /* Link BUFF into the send queue. */ 5451da177e4SLinus Torvalds __skb_append(skb, buff); 5461da177e4SLinus Torvalds 5471da177e4SLinus Torvalds return 0; 5481da177e4SLinus Torvalds } 5491da177e4SLinus Torvalds 5501da177e4SLinus Torvalds /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c 5511da177e4SLinus Torvalds * eventually). The difference is that pulled data not copied, but 5521da177e4SLinus Torvalds * immediately discarded. 5531da177e4SLinus Torvalds */ 5541da177e4SLinus Torvalds static unsigned char *__pskb_trim_head(struct sk_buff *skb, int len) 5551da177e4SLinus Torvalds { 5561da177e4SLinus Torvalds int i, k, eat; 5571da177e4SLinus Torvalds 5581da177e4SLinus Torvalds eat = len; 5591da177e4SLinus Torvalds k = 0; 5601da177e4SLinus Torvalds for (i=0; i<skb_shinfo(skb)->nr_frags; i++) { 5611da177e4SLinus Torvalds if (skb_shinfo(skb)->frags[i].size <= eat) { 5621da177e4SLinus Torvalds put_page(skb_shinfo(skb)->frags[i].page); 5631da177e4SLinus Torvalds eat -= skb_shinfo(skb)->frags[i].size; 5641da177e4SLinus Torvalds } else { 5651da177e4SLinus Torvalds skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; 5661da177e4SLinus Torvalds if (eat) { 5671da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].page_offset += eat; 5681da177e4SLinus Torvalds skb_shinfo(skb)->frags[k].size -= eat; 5691da177e4SLinus Torvalds eat = 0; 5701da177e4SLinus Torvalds } 5711da177e4SLinus Torvalds k++; 5721da177e4SLinus Torvalds } 5731da177e4SLinus Torvalds } 5741da177e4SLinus Torvalds skb_shinfo(skb)->nr_frags = k; 5751da177e4SLinus Torvalds 5761da177e4SLinus Torvalds skb->tail = skb->data; 5771da177e4SLinus Torvalds skb->data_len -= len; 5781da177e4SLinus Torvalds skb->len = skb->data_len; 5791da177e4SLinus Torvalds return skb->tail; 5801da177e4SLinus Torvalds } 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) 5831da177e4SLinus Torvalds { 5841da177e4SLinus Torvalds if (skb_cloned(skb) && 5851da177e4SLinus Torvalds pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 5861da177e4SLinus Torvalds return -ENOMEM; 5871da177e4SLinus Torvalds 5881da177e4SLinus Torvalds if (len <= skb_headlen(skb)) { 5891da177e4SLinus Torvalds __skb_pull(skb, len); 5901da177e4SLinus Torvalds } else { 5911da177e4SLinus Torvalds if (__pskb_trim_head(skb, len-skb_headlen(skb)) == NULL) 5921da177e4SLinus Torvalds return -ENOMEM; 5931da177e4SLinus Torvalds } 5941da177e4SLinus Torvalds 5951da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq += len; 5961da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_HW; 5971da177e4SLinus Torvalds 5981da177e4SLinus Torvalds skb->truesize -= len; 5991da177e4SLinus Torvalds sk->sk_wmem_queued -= len; 6001da177e4SLinus Torvalds sk->sk_forward_alloc += len; 6011da177e4SLinus Torvalds sock_set_flag(sk, SOCK_QUEUE_SHRUNK); 6021da177e4SLinus Torvalds 6031da177e4SLinus Torvalds /* Any change of skb->len requires recalculation of tso 6041da177e4SLinus Torvalds * factor and mss. 6051da177e4SLinus Torvalds */ 6061da177e4SLinus Torvalds if (tcp_skb_pcount(skb) > 1) 607d5ac99a6SDavid S. Miller tcp_set_skb_tso_segs(sk, skb); 6081da177e4SLinus Torvalds 6091da177e4SLinus Torvalds return 0; 6101da177e4SLinus Torvalds } 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds /* This function synchronize snd mss to current pmtu/exthdr set. 6131da177e4SLinus Torvalds 6141da177e4SLinus Torvalds tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts 6151da177e4SLinus Torvalds for TCP options, but includes only bare TCP header. 6161da177e4SLinus Torvalds 6171da177e4SLinus Torvalds tp->rx_opt.mss_clamp is mss negotiated at connection setup. 6181da177e4SLinus Torvalds It is minumum of user_mss and mss received with SYN. 6191da177e4SLinus Torvalds It also does not include TCP options. 6201da177e4SLinus Torvalds 6211da177e4SLinus Torvalds tp->pmtu_cookie is last pmtu, seen by this function. 6221da177e4SLinus Torvalds 6231da177e4SLinus Torvalds tp->mss_cache is current effective sending mss, including 6241da177e4SLinus Torvalds all tcp options except for SACKs. It is evaluated, 6251da177e4SLinus Torvalds taking into account current pmtu, but never exceeds 6261da177e4SLinus Torvalds tp->rx_opt.mss_clamp. 6271da177e4SLinus Torvalds 6281da177e4SLinus Torvalds NOTE1. rfc1122 clearly states that advertised MSS 6291da177e4SLinus Torvalds DOES NOT include either tcp or ip options. 6301da177e4SLinus Torvalds 6311da177e4SLinus Torvalds NOTE2. tp->pmtu_cookie and tp->mss_cache are READ ONLY outside 6321da177e4SLinus Torvalds this function. --ANK (980731) 6331da177e4SLinus Torvalds */ 6341da177e4SLinus Torvalds 6351da177e4SLinus Torvalds unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) 6361da177e4SLinus Torvalds { 6371da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 6381da177e4SLinus Torvalds int mss_now; 6391da177e4SLinus Torvalds 6401da177e4SLinus Torvalds /* Calculate base mss without TCP options: 6411da177e4SLinus Torvalds It is MMS_S - sizeof(tcphdr) of rfc1122 6421da177e4SLinus Torvalds */ 6431da177e4SLinus Torvalds mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct tcphdr); 6441da177e4SLinus Torvalds 6451da177e4SLinus Torvalds /* Clamp it (mss_clamp does not include tcp options) */ 6461da177e4SLinus Torvalds if (mss_now > tp->rx_opt.mss_clamp) 6471da177e4SLinus Torvalds mss_now = tp->rx_opt.mss_clamp; 6481da177e4SLinus Torvalds 6491da177e4SLinus Torvalds /* Now subtract optional transport overhead */ 6501da177e4SLinus Torvalds mss_now -= tp->ext_header_len; 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds /* Then reserve room for full set of TCP options and 8 bytes of data */ 6531da177e4SLinus Torvalds if (mss_now < 48) 6541da177e4SLinus Torvalds mss_now = 48; 6551da177e4SLinus Torvalds 6561da177e4SLinus Torvalds /* Now subtract TCP options size, not including SACKs */ 6571da177e4SLinus Torvalds mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); 6581da177e4SLinus Torvalds 6591da177e4SLinus Torvalds /* Bound mss with half of window */ 6601da177e4SLinus Torvalds if (tp->max_window && mss_now > (tp->max_window>>1)) 6611da177e4SLinus Torvalds mss_now = max((tp->max_window>>1), 68U - tp->tcp_header_len); 6621da177e4SLinus Torvalds 6631da177e4SLinus Torvalds /* And store cached results */ 6641da177e4SLinus Torvalds tp->pmtu_cookie = pmtu; 6651da177e4SLinus Torvalds tp->mss_cache = tp->mss_cache_std = mss_now; 6661da177e4SLinus Torvalds 6671da177e4SLinus Torvalds return mss_now; 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds 6701da177e4SLinus Torvalds /* Compute the current effective MSS, taking SACKs and IP options, 6711da177e4SLinus Torvalds * and even PMTU discovery events into account. 6721da177e4SLinus Torvalds * 6731da177e4SLinus Torvalds * LARGESEND note: !urg_mode is overkill, only frames up to snd_up 6741da177e4SLinus Torvalds * cannot be large. However, taking into account rare use of URG, this 6751da177e4SLinus Torvalds * is not a big flaw. 6761da177e4SLinus Torvalds */ 6771da177e4SLinus Torvalds 6781da177e4SLinus Torvalds unsigned int tcp_current_mss(struct sock *sk, int large) 6791da177e4SLinus Torvalds { 6801da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 6811da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 6821da177e4SLinus Torvalds unsigned int do_large, mss_now; 6831da177e4SLinus Torvalds 6841da177e4SLinus Torvalds mss_now = tp->mss_cache_std; 6851da177e4SLinus Torvalds if (dst) { 6861da177e4SLinus Torvalds u32 mtu = dst_mtu(dst); 6871da177e4SLinus Torvalds if (mtu != tp->pmtu_cookie) 6881da177e4SLinus Torvalds mss_now = tcp_sync_mss(sk, mtu); 6891da177e4SLinus Torvalds } 6901da177e4SLinus Torvalds 6911da177e4SLinus Torvalds do_large = (large && 6921da177e4SLinus Torvalds (sk->sk_route_caps & NETIF_F_TSO) && 6931da177e4SLinus Torvalds !tp->urg_mode); 6941da177e4SLinus Torvalds 6951da177e4SLinus Torvalds if (do_large) { 6961da177e4SLinus Torvalds unsigned int large_mss, factor, limit; 6971da177e4SLinus Torvalds 6981da177e4SLinus Torvalds large_mss = 65535 - tp->af_specific->net_header_len - 6991da177e4SLinus Torvalds tp->ext_header_len - tp->tcp_header_len; 7001da177e4SLinus Torvalds 7011da177e4SLinus Torvalds if (tp->max_window && large_mss > (tp->max_window>>1)) 7021da177e4SLinus Torvalds large_mss = max((tp->max_window>>1), 7031da177e4SLinus Torvalds 68U - tp->tcp_header_len); 7041da177e4SLinus Torvalds 7051da177e4SLinus Torvalds factor = large_mss / mss_now; 7061da177e4SLinus Torvalds 7071da177e4SLinus Torvalds /* Always keep large mss multiple of real mss, but 7081da177e4SLinus Torvalds * do not exceed 1/tso_win_divisor of the congestion window 7091da177e4SLinus Torvalds * so we can keep the ACK clock ticking and minimize 7101da177e4SLinus Torvalds * bursting. 7111da177e4SLinus Torvalds */ 7121da177e4SLinus Torvalds limit = tp->snd_cwnd; 7131da177e4SLinus Torvalds if (sysctl_tcp_tso_win_divisor) 7141da177e4SLinus Torvalds limit /= sysctl_tcp_tso_win_divisor; 7151da177e4SLinus Torvalds limit = max(1U, limit); 7161da177e4SLinus Torvalds if (factor > limit) 7171da177e4SLinus Torvalds factor = limit; 7181da177e4SLinus Torvalds 7191da177e4SLinus Torvalds tp->mss_cache = mss_now * factor; 7201da177e4SLinus Torvalds 7211da177e4SLinus Torvalds mss_now = tp->mss_cache; 7221da177e4SLinus Torvalds } 7231da177e4SLinus Torvalds 7241da177e4SLinus Torvalds if (tp->rx_opt.eff_sacks) 7251da177e4SLinus Torvalds mss_now -= (TCPOLEN_SACK_BASE_ALIGNED + 7261da177e4SLinus Torvalds (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); 7271da177e4SLinus Torvalds return mss_now; 7281da177e4SLinus Torvalds } 7291da177e4SLinus Torvalds 7301da177e4SLinus Torvalds /* This routine writes packets to the network. It advances the 7311da177e4SLinus Torvalds * send_head. This happens as incoming acks open up the remote 7321da177e4SLinus Torvalds * window for us. 7331da177e4SLinus Torvalds * 7341da177e4SLinus Torvalds * Returns 1, if no segments are in flight and we have queued segments, but 7351da177e4SLinus Torvalds * cannot send anything now because of SWS or another problem. 7361da177e4SLinus Torvalds */ 7371da177e4SLinus Torvalds int tcp_write_xmit(struct sock *sk, int nonagle) 7381da177e4SLinus Torvalds { 7391da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 7401da177e4SLinus Torvalds unsigned int mss_now; 7411da177e4SLinus Torvalds 7421da177e4SLinus Torvalds /* If we are closed, the bytes will have to remain here. 7431da177e4SLinus Torvalds * In time closedown will finish, we empty the write queue and all 7441da177e4SLinus Torvalds * will be happy. 7451da177e4SLinus Torvalds */ 7461da177e4SLinus Torvalds if (sk->sk_state != TCP_CLOSE) { 7471da177e4SLinus Torvalds struct sk_buff *skb; 7481da177e4SLinus Torvalds int sent_pkts = 0; 7491da177e4SLinus Torvalds 7501da177e4SLinus Torvalds /* Account for SACKS, we may need to fragment due to this. 7511da177e4SLinus Torvalds * It is just like the real MSS changing on us midstream. 7521da177e4SLinus Torvalds * We also handle things correctly when the user adds some 7531da177e4SLinus Torvalds * IP options mid-stream. Silly to do, but cover it. 7541da177e4SLinus Torvalds */ 7551da177e4SLinus Torvalds mss_now = tcp_current_mss(sk, 1); 7561da177e4SLinus Torvalds 7571da177e4SLinus Torvalds while ((skb = sk->sk_send_head) && 758d5ac99a6SDavid S. Miller tcp_snd_test(sk, skb, mss_now, 7591da177e4SLinus Torvalds tcp_skb_is_last(sk, skb) ? nonagle : 7601da177e4SLinus Torvalds TCP_NAGLE_PUSH)) { 7611da177e4SLinus Torvalds if (skb->len > mss_now) { 7621da177e4SLinus Torvalds if (tcp_fragment(sk, skb, mss_now)) 7631da177e4SLinus Torvalds break; 7641da177e4SLinus Torvalds } 7651da177e4SLinus Torvalds 7661da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 7671da177e4SLinus Torvalds tcp_tso_set_push(skb); 7681da177e4SLinus Torvalds if (tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC))) 7691da177e4SLinus Torvalds break; 7701da177e4SLinus Torvalds 7711da177e4SLinus Torvalds /* Advance the send_head. This one is sent out. 7721da177e4SLinus Torvalds * This call will increment packets_out. 7731da177e4SLinus Torvalds */ 7741da177e4SLinus Torvalds update_send_head(sk, tp, skb); 7751da177e4SLinus Torvalds 7761da177e4SLinus Torvalds tcp_minshall_update(tp, mss_now, skb); 7771da177e4SLinus Torvalds sent_pkts = 1; 7781da177e4SLinus Torvalds } 7791da177e4SLinus Torvalds 7801da177e4SLinus Torvalds if (sent_pkts) { 7811da177e4SLinus Torvalds tcp_cwnd_validate(sk, tp); 7821da177e4SLinus Torvalds return 0; 7831da177e4SLinus Torvalds } 7841da177e4SLinus Torvalds 7851da177e4SLinus Torvalds return !tp->packets_out && sk->sk_send_head; 7861da177e4SLinus Torvalds } 7871da177e4SLinus Torvalds return 0; 7881da177e4SLinus Torvalds } 7891da177e4SLinus Torvalds 7901da177e4SLinus Torvalds /* This function returns the amount that we can raise the 7911da177e4SLinus Torvalds * usable window based on the following constraints 7921da177e4SLinus Torvalds * 7931da177e4SLinus Torvalds * 1. The window can never be shrunk once it is offered (RFC 793) 7941da177e4SLinus Torvalds * 2. We limit memory per socket 7951da177e4SLinus Torvalds * 7961da177e4SLinus Torvalds * RFC 1122: 7971da177e4SLinus Torvalds * "the suggested [SWS] avoidance algorithm for the receiver is to keep 7981da177e4SLinus Torvalds * RECV.NEXT + RCV.WIN fixed until: 7991da177e4SLinus Torvalds * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" 8001da177e4SLinus Torvalds * 8011da177e4SLinus Torvalds * i.e. don't raise the right edge of the window until you can raise 8021da177e4SLinus Torvalds * it at least MSS bytes. 8031da177e4SLinus Torvalds * 8041da177e4SLinus Torvalds * Unfortunately, the recommended algorithm breaks header prediction, 8051da177e4SLinus Torvalds * since header prediction assumes th->window stays fixed. 8061da177e4SLinus Torvalds * 8071da177e4SLinus Torvalds * Strictly speaking, keeping th->window fixed violates the receiver 8081da177e4SLinus Torvalds * side SWS prevention criteria. The problem is that under this rule 8091da177e4SLinus Torvalds * a stream of single byte packets will cause the right side of the 8101da177e4SLinus Torvalds * window to always advance by a single byte. 8111da177e4SLinus Torvalds * 8121da177e4SLinus Torvalds * Of course, if the sender implements sender side SWS prevention 8131da177e4SLinus Torvalds * then this will not be a problem. 8141da177e4SLinus Torvalds * 8151da177e4SLinus Torvalds * BSD seems to make the following compromise: 8161da177e4SLinus Torvalds * 8171da177e4SLinus Torvalds * If the free space is less than the 1/4 of the maximum 8181da177e4SLinus Torvalds * space available and the free space is less than 1/2 mss, 8191da177e4SLinus Torvalds * then set the window to 0. 8201da177e4SLinus Torvalds * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] 8211da177e4SLinus Torvalds * Otherwise, just prevent the window from shrinking 8221da177e4SLinus Torvalds * and from being larger than the largest representable value. 8231da177e4SLinus Torvalds * 8241da177e4SLinus Torvalds * This prevents incremental opening of the window in the regime 8251da177e4SLinus Torvalds * where TCP is limited by the speed of the reader side taking 8261da177e4SLinus Torvalds * data out of the TCP receive queue. It does nothing about 8271da177e4SLinus Torvalds * those cases where the window is constrained on the sender side 8281da177e4SLinus Torvalds * because the pipeline is full. 8291da177e4SLinus Torvalds * 8301da177e4SLinus Torvalds * BSD also seems to "accidentally" limit itself to windows that are a 8311da177e4SLinus Torvalds * multiple of MSS, at least until the free space gets quite small. 8321da177e4SLinus Torvalds * This would appear to be a side effect of the mbuf implementation. 8331da177e4SLinus Torvalds * Combining these two algorithms results in the observed behavior 8341da177e4SLinus Torvalds * of having a fixed window size at almost all times. 8351da177e4SLinus Torvalds * 8361da177e4SLinus Torvalds * Below we obtain similar behavior by forcing the offered window to 8371da177e4SLinus Torvalds * a multiple of the mss when it is feasible to do so. 8381da177e4SLinus Torvalds * 8391da177e4SLinus Torvalds * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. 8401da177e4SLinus Torvalds * Regular options like TIMESTAMP are taken into account. 8411da177e4SLinus Torvalds */ 8421da177e4SLinus Torvalds u32 __tcp_select_window(struct sock *sk) 8431da177e4SLinus Torvalds { 8441da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 8451da177e4SLinus Torvalds /* MSS for the peer's data. Previous verions used mss_clamp 8461da177e4SLinus Torvalds * here. I don't know if the value based on our guesses 8471da177e4SLinus Torvalds * of peer's MSS is better for the performance. It's more correct 8481da177e4SLinus Torvalds * but may be worse for the performance because of rcv_mss 8491da177e4SLinus Torvalds * fluctuations. --SAW 1998/11/1 8501da177e4SLinus Torvalds */ 8511da177e4SLinus Torvalds int mss = tp->ack.rcv_mss; 8521da177e4SLinus Torvalds int free_space = tcp_space(sk); 8531da177e4SLinus Torvalds int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); 8541da177e4SLinus Torvalds int window; 8551da177e4SLinus Torvalds 8561da177e4SLinus Torvalds if (mss > full_space) 8571da177e4SLinus Torvalds mss = full_space; 8581da177e4SLinus Torvalds 8591da177e4SLinus Torvalds if (free_space < full_space/2) { 8601da177e4SLinus Torvalds tp->ack.quick = 0; 8611da177e4SLinus Torvalds 8621da177e4SLinus Torvalds if (tcp_memory_pressure) 8631da177e4SLinus Torvalds tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U*tp->advmss); 8641da177e4SLinus Torvalds 8651da177e4SLinus Torvalds if (free_space < mss) 8661da177e4SLinus Torvalds return 0; 8671da177e4SLinus Torvalds } 8681da177e4SLinus Torvalds 8691da177e4SLinus Torvalds if (free_space > tp->rcv_ssthresh) 8701da177e4SLinus Torvalds free_space = tp->rcv_ssthresh; 8711da177e4SLinus Torvalds 8721da177e4SLinus Torvalds /* Don't do rounding if we are using window scaling, since the 8731da177e4SLinus Torvalds * scaled window will not line up with the MSS boundary anyway. 8741da177e4SLinus Torvalds */ 8751da177e4SLinus Torvalds window = tp->rcv_wnd; 8761da177e4SLinus Torvalds if (tp->rx_opt.rcv_wscale) { 8771da177e4SLinus Torvalds window = free_space; 8781da177e4SLinus Torvalds 8791da177e4SLinus Torvalds /* Advertise enough space so that it won't get scaled away. 8801da177e4SLinus Torvalds * Import case: prevent zero window announcement if 8811da177e4SLinus Torvalds * 1<<rcv_wscale > mss. 8821da177e4SLinus Torvalds */ 8831da177e4SLinus Torvalds if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) 8841da177e4SLinus Torvalds window = (((window >> tp->rx_opt.rcv_wscale) + 1) 8851da177e4SLinus Torvalds << tp->rx_opt.rcv_wscale); 8861da177e4SLinus Torvalds } else { 8871da177e4SLinus Torvalds /* Get the largest window that is a nice multiple of mss. 8881da177e4SLinus Torvalds * Window clamp already applied above. 8891da177e4SLinus Torvalds * If our current window offering is within 1 mss of the 8901da177e4SLinus Torvalds * free space we just keep it. This prevents the divide 8911da177e4SLinus Torvalds * and multiply from happening most of the time. 8921da177e4SLinus Torvalds * We also don't do any window rounding when the free space 8931da177e4SLinus Torvalds * is too small. 8941da177e4SLinus Torvalds */ 8951da177e4SLinus Torvalds if (window <= free_space - mss || window > free_space) 8961da177e4SLinus Torvalds window = (free_space/mss)*mss; 8971da177e4SLinus Torvalds } 8981da177e4SLinus Torvalds 8991da177e4SLinus Torvalds return window; 9001da177e4SLinus Torvalds } 9011da177e4SLinus Torvalds 9021da177e4SLinus Torvalds /* Attempt to collapse two adjacent SKB's during retransmission. */ 9031da177e4SLinus Torvalds static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int mss_now) 9041da177e4SLinus Torvalds { 9051da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 9061da177e4SLinus Torvalds struct sk_buff *next_skb = skb->next; 9071da177e4SLinus Torvalds 9081da177e4SLinus Torvalds /* The first test we must make is that neither of these two 9091da177e4SLinus Torvalds * SKB's are still referenced by someone else. 9101da177e4SLinus Torvalds */ 9111da177e4SLinus Torvalds if (!skb_cloned(skb) && !skb_cloned(next_skb)) { 9121da177e4SLinus Torvalds int skb_size = skb->len, next_skb_size = next_skb->len; 9131da177e4SLinus Torvalds u16 flags = TCP_SKB_CB(skb)->flags; 9141da177e4SLinus Torvalds 9151da177e4SLinus Torvalds /* Also punt if next skb has been SACK'd. */ 9161da177e4SLinus Torvalds if(TCP_SKB_CB(next_skb)->sacked & TCPCB_SACKED_ACKED) 9171da177e4SLinus Torvalds return; 9181da177e4SLinus Torvalds 9191da177e4SLinus Torvalds /* Next skb is out of window. */ 9201da177e4SLinus Torvalds if (after(TCP_SKB_CB(next_skb)->end_seq, tp->snd_una+tp->snd_wnd)) 9211da177e4SLinus Torvalds return; 9221da177e4SLinus Torvalds 9231da177e4SLinus Torvalds /* Punt if not enough space exists in the first SKB for 9241da177e4SLinus Torvalds * the data in the second, or the total combined payload 9251da177e4SLinus Torvalds * would exceed the MSS. 9261da177e4SLinus Torvalds */ 9271da177e4SLinus Torvalds if ((next_skb_size > skb_tailroom(skb)) || 9281da177e4SLinus Torvalds ((skb_size + next_skb_size) > mss_now)) 9291da177e4SLinus Torvalds return; 9301da177e4SLinus Torvalds 9311da177e4SLinus Torvalds BUG_ON(tcp_skb_pcount(skb) != 1 || 9321da177e4SLinus Torvalds tcp_skb_pcount(next_skb) != 1); 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds /* Ok. We will be able to collapse the packet. */ 9351da177e4SLinus Torvalds __skb_unlink(next_skb, next_skb->list); 9361da177e4SLinus Torvalds 9371da177e4SLinus Torvalds memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size); 9381da177e4SLinus Torvalds 9391da177e4SLinus Torvalds if (next_skb->ip_summed == CHECKSUM_HW) 9401da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_HW; 9411da177e4SLinus Torvalds 9421da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_HW) 9431da177e4SLinus Torvalds skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); 9441da177e4SLinus Torvalds 9451da177e4SLinus Torvalds /* Update sequence range on original skb. */ 9461da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; 9471da177e4SLinus Torvalds 9481da177e4SLinus Torvalds /* Merge over control information. */ 9491da177e4SLinus Torvalds flags |= TCP_SKB_CB(next_skb)->flags; /* This moves PSH/FIN etc. over */ 9501da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = flags; 9511da177e4SLinus Torvalds 9521da177e4SLinus Torvalds /* All done, get rid of second SKB and account for it so 9531da177e4SLinus Torvalds * packet counting does not break. 9541da177e4SLinus Torvalds */ 9551da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked&(TCPCB_EVER_RETRANS|TCPCB_AT_TAIL); 9561da177e4SLinus Torvalds if (TCP_SKB_CB(next_skb)->sacked&TCPCB_SACKED_RETRANS) 9571da177e4SLinus Torvalds tp->retrans_out -= tcp_skb_pcount(next_skb); 9581da177e4SLinus Torvalds if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST) { 9591da177e4SLinus Torvalds tp->lost_out -= tcp_skb_pcount(next_skb); 9601da177e4SLinus Torvalds tp->left_out -= tcp_skb_pcount(next_skb); 9611da177e4SLinus Torvalds } 9621da177e4SLinus Torvalds /* Reno case is special. Sigh... */ 9631da177e4SLinus Torvalds if (!tp->rx_opt.sack_ok && tp->sacked_out) { 9641da177e4SLinus Torvalds tcp_dec_pcount_approx(&tp->sacked_out, next_skb); 9651da177e4SLinus Torvalds tp->left_out -= tcp_skb_pcount(next_skb); 9661da177e4SLinus Torvalds } 9671da177e4SLinus Torvalds 9681da177e4SLinus Torvalds /* Not quite right: it can be > snd.fack, but 9691da177e4SLinus Torvalds * it is better to underestimate fackets. 9701da177e4SLinus Torvalds */ 9711da177e4SLinus Torvalds tcp_dec_pcount_approx(&tp->fackets_out, next_skb); 9721da177e4SLinus Torvalds tcp_packets_out_dec(tp, next_skb); 9731da177e4SLinus Torvalds sk_stream_free_skb(sk, next_skb); 9741da177e4SLinus Torvalds } 9751da177e4SLinus Torvalds } 9761da177e4SLinus Torvalds 9771da177e4SLinus Torvalds /* Do a simple retransmit without using the backoff mechanisms in 9781da177e4SLinus Torvalds * tcp_timer. This is used for path mtu discovery. 9791da177e4SLinus Torvalds * The socket is already locked here. 9801da177e4SLinus Torvalds */ 9811da177e4SLinus Torvalds void tcp_simple_retransmit(struct sock *sk) 9821da177e4SLinus Torvalds { 9831da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 9841da177e4SLinus Torvalds struct sk_buff *skb; 9851da177e4SLinus Torvalds unsigned int mss = tcp_current_mss(sk, 0); 9861da177e4SLinus Torvalds int lost = 0; 9871da177e4SLinus Torvalds 9881da177e4SLinus Torvalds sk_stream_for_retrans_queue(skb, sk) { 9891da177e4SLinus Torvalds if (skb->len > mss && 9901da177e4SLinus Torvalds !(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) { 9911da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { 9921da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; 9931da177e4SLinus Torvalds tp->retrans_out -= tcp_skb_pcount(skb); 9941da177e4SLinus Torvalds } 9951da177e4SLinus Torvalds if (!(TCP_SKB_CB(skb)->sacked&TCPCB_LOST)) { 9961da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; 9971da177e4SLinus Torvalds tp->lost_out += tcp_skb_pcount(skb); 9981da177e4SLinus Torvalds lost = 1; 9991da177e4SLinus Torvalds } 10001da177e4SLinus Torvalds } 10011da177e4SLinus Torvalds } 10021da177e4SLinus Torvalds 10031da177e4SLinus Torvalds if (!lost) 10041da177e4SLinus Torvalds return; 10051da177e4SLinus Torvalds 10061da177e4SLinus Torvalds tcp_sync_left_out(tp); 10071da177e4SLinus Torvalds 10081da177e4SLinus Torvalds /* Don't muck with the congestion window here. 10091da177e4SLinus Torvalds * Reason is that we do not increase amount of _data_ 10101da177e4SLinus Torvalds * in network, but units changed and effective 10111da177e4SLinus Torvalds * cwnd/ssthresh really reduced now. 10121da177e4SLinus Torvalds */ 10131da177e4SLinus Torvalds if (tp->ca_state != TCP_CA_Loss) { 10141da177e4SLinus Torvalds tp->high_seq = tp->snd_nxt; 10151da177e4SLinus Torvalds tp->snd_ssthresh = tcp_current_ssthresh(tp); 10161da177e4SLinus Torvalds tp->prior_ssthresh = 0; 10171da177e4SLinus Torvalds tp->undo_marker = 0; 10181da177e4SLinus Torvalds tcp_set_ca_state(tp, TCP_CA_Loss); 10191da177e4SLinus Torvalds } 10201da177e4SLinus Torvalds tcp_xmit_retransmit_queue(sk); 10211da177e4SLinus Torvalds } 10221da177e4SLinus Torvalds 10231da177e4SLinus Torvalds /* This retransmits one SKB. Policy decisions and retransmit queue 10241da177e4SLinus Torvalds * state updates are done by the caller. Returns non-zero if an 10251da177e4SLinus Torvalds * error occurred which prevented the send. 10261da177e4SLinus Torvalds */ 10271da177e4SLinus Torvalds int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) 10281da177e4SLinus Torvalds { 10291da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 10301da177e4SLinus Torvalds unsigned int cur_mss = tcp_current_mss(sk, 0); 10311da177e4SLinus Torvalds int err; 10321da177e4SLinus Torvalds 10331da177e4SLinus Torvalds /* Do not sent more than we queued. 1/4 is reserved for possible 10341da177e4SLinus Torvalds * copying overhead: frgagmentation, tunneling, mangling etc. 10351da177e4SLinus Torvalds */ 10361da177e4SLinus Torvalds if (atomic_read(&sk->sk_wmem_alloc) > 10371da177e4SLinus Torvalds min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) 10381da177e4SLinus Torvalds return -EAGAIN; 10391da177e4SLinus Torvalds 10401da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { 10411da177e4SLinus Torvalds if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) 10421da177e4SLinus Torvalds BUG(); 10431da177e4SLinus Torvalds 10441da177e4SLinus Torvalds if (sk->sk_route_caps & NETIF_F_TSO) { 10451da177e4SLinus Torvalds sk->sk_route_caps &= ~NETIF_F_TSO; 10461da177e4SLinus Torvalds sock_set_flag(sk, SOCK_NO_LARGESEND); 10471da177e4SLinus Torvalds tp->mss_cache = tp->mss_cache_std; 10481da177e4SLinus Torvalds } 10491da177e4SLinus Torvalds 10501da177e4SLinus Torvalds if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) 10511da177e4SLinus Torvalds return -ENOMEM; 10521da177e4SLinus Torvalds } 10531da177e4SLinus Torvalds 10541da177e4SLinus Torvalds /* If receiver has shrunk his window, and skb is out of 10551da177e4SLinus Torvalds * new window, do not retransmit it. The exception is the 10561da177e4SLinus Torvalds * case, when window is shrunk to zero. In this case 10571da177e4SLinus Torvalds * our retransmit serves as a zero window probe. 10581da177e4SLinus Torvalds */ 10591da177e4SLinus Torvalds if (!before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd) 10601da177e4SLinus Torvalds && TCP_SKB_CB(skb)->seq != tp->snd_una) 10611da177e4SLinus Torvalds return -EAGAIN; 10621da177e4SLinus Torvalds 10631da177e4SLinus Torvalds if (skb->len > cur_mss) { 10641da177e4SLinus Torvalds int old_factor = tcp_skb_pcount(skb); 10651da177e4SLinus Torvalds int new_factor; 10661da177e4SLinus Torvalds 10671da177e4SLinus Torvalds if (tcp_fragment(sk, skb, cur_mss)) 10681da177e4SLinus Torvalds return -ENOMEM; /* We'll try again later. */ 10691da177e4SLinus Torvalds 10701da177e4SLinus Torvalds /* New SKB created, account for it. */ 10711da177e4SLinus Torvalds new_factor = tcp_skb_pcount(skb); 10721da177e4SLinus Torvalds tp->packets_out -= old_factor - new_factor; 10731da177e4SLinus Torvalds tp->packets_out += tcp_skb_pcount(skb->next); 10741da177e4SLinus Torvalds } 10751da177e4SLinus Torvalds 10761da177e4SLinus Torvalds /* Collapse two adjacent packets if worthwhile and we can. */ 10771da177e4SLinus Torvalds if(!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN) && 10781da177e4SLinus Torvalds (skb->len < (cur_mss >> 1)) && 10791da177e4SLinus Torvalds (skb->next != sk->sk_send_head) && 10801da177e4SLinus Torvalds (skb->next != (struct sk_buff *)&sk->sk_write_queue) && 10811da177e4SLinus Torvalds (skb_shinfo(skb)->nr_frags == 0 && skb_shinfo(skb->next)->nr_frags == 0) && 10821da177e4SLinus Torvalds (tcp_skb_pcount(skb) == 1 && tcp_skb_pcount(skb->next) == 1) && 10831da177e4SLinus Torvalds (sysctl_tcp_retrans_collapse != 0)) 10841da177e4SLinus Torvalds tcp_retrans_try_collapse(sk, skb, cur_mss); 10851da177e4SLinus Torvalds 10861da177e4SLinus Torvalds if(tp->af_specific->rebuild_header(sk)) 10871da177e4SLinus Torvalds return -EHOSTUNREACH; /* Routing failure or similar. */ 10881da177e4SLinus Torvalds 10891da177e4SLinus Torvalds /* Some Solaris stacks overoptimize and ignore the FIN on a 10901da177e4SLinus Torvalds * retransmit when old data is attached. So strip it off 10911da177e4SLinus Torvalds * since it is cheap to do so and saves bytes on the network. 10921da177e4SLinus Torvalds */ 10931da177e4SLinus Torvalds if(skb->len > 0 && 10941da177e4SLinus Torvalds (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && 10951da177e4SLinus Torvalds tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { 10961da177e4SLinus Torvalds if (!pskb_trim(skb, 0)) { 10971da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1; 10981da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 10991da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 11001da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 11011da177e4SLinus Torvalds skb->csum = 0; 11021da177e4SLinus Torvalds } 11031da177e4SLinus Torvalds } 11041da177e4SLinus Torvalds 11051da177e4SLinus Torvalds /* Make a copy, if the first transmission SKB clone we made 11061da177e4SLinus Torvalds * is still in somebody's hands, else make a clone. 11071da177e4SLinus Torvalds */ 11081da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 11091da177e4SLinus Torvalds tcp_tso_set_push(skb); 11101da177e4SLinus Torvalds 11111da177e4SLinus Torvalds err = tcp_transmit_skb(sk, (skb_cloned(skb) ? 11121da177e4SLinus Torvalds pskb_copy(skb, GFP_ATOMIC): 11131da177e4SLinus Torvalds skb_clone(skb, GFP_ATOMIC))); 11141da177e4SLinus Torvalds 11151da177e4SLinus Torvalds if (err == 0) { 11161da177e4SLinus Torvalds /* Update global TCP statistics. */ 11171da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_RETRANSSEGS); 11181da177e4SLinus Torvalds 11191da177e4SLinus Torvalds tp->total_retrans++; 11201da177e4SLinus Torvalds 11211da177e4SLinus Torvalds #if FASTRETRANS_DEBUG > 0 11221da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { 11231da177e4SLinus Torvalds if (net_ratelimit()) 11241da177e4SLinus Torvalds printk(KERN_DEBUG "retrans_out leaked.\n"); 11251da177e4SLinus Torvalds } 11261da177e4SLinus Torvalds #endif 11271da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; 11281da177e4SLinus Torvalds tp->retrans_out += tcp_skb_pcount(skb); 11291da177e4SLinus Torvalds 11301da177e4SLinus Torvalds /* Save stamp of the first retransmit. */ 11311da177e4SLinus Torvalds if (!tp->retrans_stamp) 11321da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(skb)->when; 11331da177e4SLinus Torvalds 11341da177e4SLinus Torvalds tp->undo_retrans++; 11351da177e4SLinus Torvalds 11361da177e4SLinus Torvalds /* snd_nxt is stored to detect loss of retransmitted segment, 11371da177e4SLinus Torvalds * see tcp_input.c tcp_sacktag_write_queue(). 11381da177e4SLinus Torvalds */ 11391da177e4SLinus Torvalds TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; 11401da177e4SLinus Torvalds } 11411da177e4SLinus Torvalds return err; 11421da177e4SLinus Torvalds } 11431da177e4SLinus Torvalds 11441da177e4SLinus Torvalds /* This gets called after a retransmit timeout, and the initially 11451da177e4SLinus Torvalds * retransmitted data is acknowledged. It tries to continue 11461da177e4SLinus Torvalds * resending the rest of the retransmit queue, until either 11471da177e4SLinus Torvalds * we've sent it all or the congestion window limit is reached. 11481da177e4SLinus Torvalds * If doing SACK, the first ACK which comes back for a timeout 11491da177e4SLinus Torvalds * based retransmit packet might feed us FACK information again. 11501da177e4SLinus Torvalds * If so, we use it to avoid unnecessarily retransmissions. 11511da177e4SLinus Torvalds */ 11521da177e4SLinus Torvalds void tcp_xmit_retransmit_queue(struct sock *sk) 11531da177e4SLinus Torvalds { 11541da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 11551da177e4SLinus Torvalds struct sk_buff *skb; 11561da177e4SLinus Torvalds int packet_cnt = tp->lost_out; 11571da177e4SLinus Torvalds 11581da177e4SLinus Torvalds /* First pass: retransmit lost packets. */ 11591da177e4SLinus Torvalds if (packet_cnt) { 11601da177e4SLinus Torvalds sk_stream_for_retrans_queue(skb, sk) { 11611da177e4SLinus Torvalds __u8 sacked = TCP_SKB_CB(skb)->sacked; 11621da177e4SLinus Torvalds 11631da177e4SLinus Torvalds /* Assume this retransmit will generate 11641da177e4SLinus Torvalds * only one packet for congestion window 11651da177e4SLinus Torvalds * calculation purposes. This works because 11661da177e4SLinus Torvalds * tcp_retransmit_skb() will chop up the 11671da177e4SLinus Torvalds * packet to be MSS sized and all the 11681da177e4SLinus Torvalds * packet counting works out. 11691da177e4SLinus Torvalds */ 11701da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 11711da177e4SLinus Torvalds return; 11721da177e4SLinus Torvalds 11731da177e4SLinus Torvalds if (sacked&TCPCB_LOST) { 11741da177e4SLinus Torvalds if (!(sacked&(TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) { 11751da177e4SLinus Torvalds if (tcp_retransmit_skb(sk, skb)) 11761da177e4SLinus Torvalds return; 11771da177e4SLinus Torvalds if (tp->ca_state != TCP_CA_Loss) 11781da177e4SLinus Torvalds NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS); 11791da177e4SLinus Torvalds else 11801da177e4SLinus Torvalds NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS); 11811da177e4SLinus Torvalds 11821da177e4SLinus Torvalds if (skb == 11831da177e4SLinus Torvalds skb_peek(&sk->sk_write_queue)) 11841da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); 11851da177e4SLinus Torvalds } 11861da177e4SLinus Torvalds 11871da177e4SLinus Torvalds packet_cnt -= tcp_skb_pcount(skb); 11881da177e4SLinus Torvalds if (packet_cnt <= 0) 11891da177e4SLinus Torvalds break; 11901da177e4SLinus Torvalds } 11911da177e4SLinus Torvalds } 11921da177e4SLinus Torvalds } 11931da177e4SLinus Torvalds 11941da177e4SLinus Torvalds /* OK, demanded retransmission is finished. */ 11951da177e4SLinus Torvalds 11961da177e4SLinus Torvalds /* Forward retransmissions are possible only during Recovery. */ 11971da177e4SLinus Torvalds if (tp->ca_state != TCP_CA_Recovery) 11981da177e4SLinus Torvalds return; 11991da177e4SLinus Torvalds 12001da177e4SLinus Torvalds /* No forward retransmissions in Reno are possible. */ 12011da177e4SLinus Torvalds if (!tp->rx_opt.sack_ok) 12021da177e4SLinus Torvalds return; 12031da177e4SLinus Torvalds 12041da177e4SLinus Torvalds /* Yeah, we have to make difficult choice between forward transmission 12051da177e4SLinus Torvalds * and retransmission... Both ways have their merits... 12061da177e4SLinus Torvalds * 12071da177e4SLinus Torvalds * For now we do not retransmit anything, while we have some new 12081da177e4SLinus Torvalds * segments to send. 12091da177e4SLinus Torvalds */ 12101da177e4SLinus Torvalds 12111da177e4SLinus Torvalds if (tcp_may_send_now(sk, tp)) 12121da177e4SLinus Torvalds return; 12131da177e4SLinus Torvalds 12141da177e4SLinus Torvalds packet_cnt = 0; 12151da177e4SLinus Torvalds 12161da177e4SLinus Torvalds sk_stream_for_retrans_queue(skb, sk) { 12171da177e4SLinus Torvalds /* Similar to the retransmit loop above we 12181da177e4SLinus Torvalds * can pretend that the retransmitted SKB 12191da177e4SLinus Torvalds * we send out here will be composed of one 12201da177e4SLinus Torvalds * real MSS sized packet because tcp_retransmit_skb() 12211da177e4SLinus Torvalds * will fragment it if necessary. 12221da177e4SLinus Torvalds */ 12231da177e4SLinus Torvalds if (++packet_cnt > tp->fackets_out) 12241da177e4SLinus Torvalds break; 12251da177e4SLinus Torvalds 12261da177e4SLinus Torvalds if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) 12271da177e4SLinus Torvalds break; 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) 12301da177e4SLinus Torvalds continue; 12311da177e4SLinus Torvalds 12321da177e4SLinus Torvalds /* Ok, retransmit it. */ 12331da177e4SLinus Torvalds if (tcp_retransmit_skb(sk, skb)) 12341da177e4SLinus Torvalds break; 12351da177e4SLinus Torvalds 12361da177e4SLinus Torvalds if (skb == skb_peek(&sk->sk_write_queue)) 12371da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); 12381da177e4SLinus Torvalds 12391da177e4SLinus Torvalds NET_INC_STATS_BH(LINUX_MIB_TCPFORWARDRETRANS); 12401da177e4SLinus Torvalds } 12411da177e4SLinus Torvalds } 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds 12441da177e4SLinus Torvalds /* Send a fin. The caller locks the socket for us. This cannot be 12451da177e4SLinus Torvalds * allowed to fail queueing a FIN frame under any circumstances. 12461da177e4SLinus Torvalds */ 12471da177e4SLinus Torvalds void tcp_send_fin(struct sock *sk) 12481da177e4SLinus Torvalds { 12491da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12501da177e4SLinus Torvalds struct sk_buff *skb = skb_peek_tail(&sk->sk_write_queue); 12511da177e4SLinus Torvalds int mss_now; 12521da177e4SLinus Torvalds 12531da177e4SLinus Torvalds /* Optimization, tack on the FIN if we have a queue of 12541da177e4SLinus Torvalds * unsent frames. But be careful about outgoing SACKS 12551da177e4SLinus Torvalds * and IP options. 12561da177e4SLinus Torvalds */ 12571da177e4SLinus Torvalds mss_now = tcp_current_mss(sk, 1); 12581da177e4SLinus Torvalds 12591da177e4SLinus Torvalds if (sk->sk_send_head != NULL) { 12601da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; 12611da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq++; 12621da177e4SLinus Torvalds tp->write_seq++; 12631da177e4SLinus Torvalds } else { 12641da177e4SLinus Torvalds /* Socket is locked, keep trying until memory is available. */ 12651da177e4SLinus Torvalds for (;;) { 12661da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_KERNEL); 12671da177e4SLinus Torvalds if (skb) 12681da177e4SLinus Torvalds break; 12691da177e4SLinus Torvalds yield(); 12701da177e4SLinus Torvalds } 12711da177e4SLinus Torvalds 12721da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 12731da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 12741da177e4SLinus Torvalds skb->csum = 0; 12751da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); 12761da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = 0; 12771da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 12781da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 12791da177e4SLinus Torvalds 12801da177e4SLinus Torvalds /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ 12811da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = tp->write_seq; 12821da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; 12831da177e4SLinus Torvalds tcp_queue_skb(sk, skb); 12841da177e4SLinus Torvalds } 12851da177e4SLinus Torvalds __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_OFF); 12861da177e4SLinus Torvalds } 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds /* We get here when a process closes a file descriptor (either due to 12891da177e4SLinus Torvalds * an explicit close() or as a byproduct of exit()'ing) and there 12901da177e4SLinus Torvalds * was unread data in the receive queue. This behavior is recommended 12911da177e4SLinus Torvalds * by draft-ietf-tcpimpl-prob-03.txt section 3.10. -DaveM 12921da177e4SLinus Torvalds */ 12931da177e4SLinus Torvalds void tcp_send_active_reset(struct sock *sk, int priority) 12941da177e4SLinus Torvalds { 12951da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 12961da177e4SLinus Torvalds struct sk_buff *skb; 12971da177e4SLinus Torvalds 12981da177e4SLinus Torvalds /* NOTE: No TCP options attached and we never retransmit this. */ 12991da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, priority); 13001da177e4SLinus Torvalds if (!skb) { 13011da177e4SLinus Torvalds NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); 13021da177e4SLinus Torvalds return; 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds 13051da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 13061da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 13071da177e4SLinus Torvalds skb->csum = 0; 13081da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST); 13091da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = 0; 13101da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 13111da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 13121da177e4SLinus Torvalds 13131da177e4SLinus Torvalds /* Send it off. */ 13141da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk, tp); 13151da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; 13161da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 13171da177e4SLinus Torvalds if (tcp_transmit_skb(sk, skb)) 13181da177e4SLinus Torvalds NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); 13191da177e4SLinus Torvalds } 13201da177e4SLinus Torvalds 13211da177e4SLinus Torvalds /* WARNING: This routine must only be called when we have already sent 13221da177e4SLinus Torvalds * a SYN packet that crossed the incoming SYN that caused this routine 13231da177e4SLinus Torvalds * to get called. If this assumption fails then the initial rcv_wnd 13241da177e4SLinus Torvalds * and rcv_wscale values will not be correct. 13251da177e4SLinus Torvalds */ 13261da177e4SLinus Torvalds int tcp_send_synack(struct sock *sk) 13271da177e4SLinus Torvalds { 13281da177e4SLinus Torvalds struct sk_buff* skb; 13291da177e4SLinus Torvalds 13301da177e4SLinus Torvalds skb = skb_peek(&sk->sk_write_queue); 13311da177e4SLinus Torvalds if (skb == NULL || !(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_SYN)) { 13321da177e4SLinus Torvalds printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); 13331da177e4SLinus Torvalds return -EFAULT; 13341da177e4SLinus Torvalds } 13351da177e4SLinus Torvalds if (!(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_ACK)) { 13361da177e4SLinus Torvalds if (skb_cloned(skb)) { 13371da177e4SLinus Torvalds struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); 13381da177e4SLinus Torvalds if (nskb == NULL) 13391da177e4SLinus Torvalds return -ENOMEM; 13401da177e4SLinus Torvalds __skb_unlink(skb, &sk->sk_write_queue); 13411da177e4SLinus Torvalds skb_header_release(nskb); 13421da177e4SLinus Torvalds __skb_queue_head(&sk->sk_write_queue, nskb); 13431da177e4SLinus Torvalds sk_stream_free_skb(sk, skb); 13441da177e4SLinus Torvalds sk_charge_skb(sk, nskb); 13451da177e4SLinus Torvalds skb = nskb; 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds 13481da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ACK; 13491da177e4SLinus Torvalds TCP_ECN_send_synack(tcp_sk(sk), skb); 13501da177e4SLinus Torvalds } 13511da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 13521da177e4SLinus Torvalds return tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)); 13531da177e4SLinus Torvalds } 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds /* 13561da177e4SLinus Torvalds * Prepare a SYN-ACK. 13571da177e4SLinus Torvalds */ 13581da177e4SLinus Torvalds struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, 13591da177e4SLinus Torvalds struct open_request *req) 13601da177e4SLinus Torvalds { 1361*2e6599cbSArnaldo Carvalho de Melo struct inet_request_sock *ireq = inet_rsk(req); 13621da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 13631da177e4SLinus Torvalds struct tcphdr *th; 13641da177e4SLinus Torvalds int tcp_header_size; 13651da177e4SLinus Torvalds struct sk_buff *skb; 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); 13681da177e4SLinus Torvalds if (skb == NULL) 13691da177e4SLinus Torvalds return NULL; 13701da177e4SLinus Torvalds 13711da177e4SLinus Torvalds /* Reserve space for headers. */ 13721da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 13731da177e4SLinus Torvalds 13741da177e4SLinus Torvalds skb->dst = dst_clone(dst); 13751da177e4SLinus Torvalds 13761da177e4SLinus Torvalds tcp_header_size = (sizeof(struct tcphdr) + TCPOLEN_MSS + 1377*2e6599cbSArnaldo Carvalho de Melo (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) + 1378*2e6599cbSArnaldo Carvalho de Melo (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) + 13791da177e4SLinus Torvalds /* SACK_PERM is in the place of NOP NOP of TS */ 1380*2e6599cbSArnaldo Carvalho de Melo ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0)); 13811da177e4SLinus Torvalds skb->h.th = th = (struct tcphdr *) skb_push(skb, tcp_header_size); 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds memset(th, 0, sizeof(struct tcphdr)); 13841da177e4SLinus Torvalds th->syn = 1; 13851da177e4SLinus Torvalds th->ack = 1; 13861da177e4SLinus Torvalds if (dst->dev->features&NETIF_F_TSO) 1387*2e6599cbSArnaldo Carvalho de Melo ireq->ecn_ok = 0; 13881da177e4SLinus Torvalds TCP_ECN_make_synack(req, th); 13891da177e4SLinus Torvalds th->source = inet_sk(sk)->sport; 1390*2e6599cbSArnaldo Carvalho de Melo th->dest = ireq->rmt_port; 1391*2e6599cbSArnaldo Carvalho de Melo TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn; 13921da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; 13931da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = 0; 13941da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 13951da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 13961da177e4SLinus Torvalds th->seq = htonl(TCP_SKB_CB(skb)->seq); 1397*2e6599cbSArnaldo Carvalho de Melo th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); 13981da177e4SLinus Torvalds if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ 13991da177e4SLinus Torvalds __u8 rcv_wscale; 14001da177e4SLinus Torvalds /* Set this up on the first call only */ 14011da177e4SLinus Torvalds req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); 14021da177e4SLinus Torvalds /* tcp_full_space because it is guaranteed to be the first packet */ 14031da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 1404*2e6599cbSArnaldo Carvalho de Melo dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), 14051da177e4SLinus Torvalds &req->rcv_wnd, 14061da177e4SLinus Torvalds &req->window_clamp, 1407*2e6599cbSArnaldo Carvalho de Melo ireq->wscale_ok, 14081da177e4SLinus Torvalds &rcv_wscale); 1409*2e6599cbSArnaldo Carvalho de Melo ireq->rcv_wscale = rcv_wscale; 14101da177e4SLinus Torvalds } 14111da177e4SLinus Torvalds 14121da177e4SLinus Torvalds /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ 14131da177e4SLinus Torvalds th->window = htons(req->rcv_wnd); 14141da177e4SLinus Torvalds 14151da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 1416*2e6599cbSArnaldo Carvalho de Melo tcp_syn_build_options((__u32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok, 1417*2e6599cbSArnaldo Carvalho de Melo ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale, 14181da177e4SLinus Torvalds TCP_SKB_CB(skb)->when, 14191da177e4SLinus Torvalds req->ts_recent); 14201da177e4SLinus Torvalds 14211da177e4SLinus Torvalds skb->csum = 0; 14221da177e4SLinus Torvalds th->doff = (tcp_header_size >> 2); 14231da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_OUTSEGS); 14241da177e4SLinus Torvalds return skb; 14251da177e4SLinus Torvalds } 14261da177e4SLinus Torvalds 14271da177e4SLinus Torvalds /* 14281da177e4SLinus Torvalds * Do all connect socket setups that can be done AF independent. 14291da177e4SLinus Torvalds */ 14301da177e4SLinus Torvalds static inline void tcp_connect_init(struct sock *sk) 14311da177e4SLinus Torvalds { 14321da177e4SLinus Torvalds struct dst_entry *dst = __sk_dst_get(sk); 14331da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 14341da177e4SLinus Torvalds __u8 rcv_wscale; 14351da177e4SLinus Torvalds 14361da177e4SLinus Torvalds /* We'll fix this up when we get a response from the other end. 14371da177e4SLinus Torvalds * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. 14381da177e4SLinus Torvalds */ 14391da177e4SLinus Torvalds tp->tcp_header_len = sizeof(struct tcphdr) + 14401da177e4SLinus Torvalds (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds /* If user gave his TCP_MAXSEG, record it to clamp */ 14431da177e4SLinus Torvalds if (tp->rx_opt.user_mss) 14441da177e4SLinus Torvalds tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; 14451da177e4SLinus Torvalds tp->max_window = 0; 14461da177e4SLinus Torvalds tcp_sync_mss(sk, dst_mtu(dst)); 14471da177e4SLinus Torvalds 14481da177e4SLinus Torvalds if (!tp->window_clamp) 14491da177e4SLinus Torvalds tp->window_clamp = dst_metric(dst, RTAX_WINDOW); 14501da177e4SLinus Torvalds tp->advmss = dst_metric(dst, RTAX_ADVMSS); 14511da177e4SLinus Torvalds tcp_initialize_rcv_mss(sk); 14521da177e4SLinus Torvalds tcp_ca_init(tp); 14531da177e4SLinus Torvalds 14541da177e4SLinus Torvalds tcp_select_initial_window(tcp_full_space(sk), 14551da177e4SLinus Torvalds tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), 14561da177e4SLinus Torvalds &tp->rcv_wnd, 14571da177e4SLinus Torvalds &tp->window_clamp, 14581da177e4SLinus Torvalds sysctl_tcp_window_scaling, 14591da177e4SLinus Torvalds &rcv_wscale); 14601da177e4SLinus Torvalds 14611da177e4SLinus Torvalds tp->rx_opt.rcv_wscale = rcv_wscale; 14621da177e4SLinus Torvalds tp->rcv_ssthresh = tp->rcv_wnd; 14631da177e4SLinus Torvalds 14641da177e4SLinus Torvalds sk->sk_err = 0; 14651da177e4SLinus Torvalds sock_reset_flag(sk, SOCK_DONE); 14661da177e4SLinus Torvalds tp->snd_wnd = 0; 14671da177e4SLinus Torvalds tcp_init_wl(tp, tp->write_seq, 0); 14681da177e4SLinus Torvalds tp->snd_una = tp->write_seq; 14691da177e4SLinus Torvalds tp->snd_sml = tp->write_seq; 14701da177e4SLinus Torvalds tp->rcv_nxt = 0; 14711da177e4SLinus Torvalds tp->rcv_wup = 0; 14721da177e4SLinus Torvalds tp->copied_seq = 0; 14731da177e4SLinus Torvalds 14741da177e4SLinus Torvalds tp->rto = TCP_TIMEOUT_INIT; 14751da177e4SLinus Torvalds tp->retransmits = 0; 14761da177e4SLinus Torvalds tcp_clear_retrans(tp); 14771da177e4SLinus Torvalds } 14781da177e4SLinus Torvalds 14791da177e4SLinus Torvalds /* 14801da177e4SLinus Torvalds * Build a SYN and send it off. 14811da177e4SLinus Torvalds */ 14821da177e4SLinus Torvalds int tcp_connect(struct sock *sk) 14831da177e4SLinus Torvalds { 14841da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 14851da177e4SLinus Torvalds struct sk_buff *buff; 14861da177e4SLinus Torvalds 14871da177e4SLinus Torvalds tcp_connect_init(sk); 14881da177e4SLinus Torvalds 14891da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER + 15, sk->sk_allocation); 14901da177e4SLinus Torvalds if (unlikely(buff == NULL)) 14911da177e4SLinus Torvalds return -ENOBUFS; 14921da177e4SLinus Torvalds 14931da177e4SLinus Torvalds /* Reserve space for headers. */ 14941da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 14951da177e4SLinus Torvalds 14961da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN; 14971da177e4SLinus Torvalds TCP_ECN_send_syn(sk, tp, buff); 14981da177e4SLinus Torvalds TCP_SKB_CB(buff)->sacked = 0; 14991da177e4SLinus Torvalds skb_shinfo(buff)->tso_segs = 1; 15001da177e4SLinus Torvalds skb_shinfo(buff)->tso_size = 0; 15011da177e4SLinus Torvalds buff->csum = 0; 15021da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = tp->write_seq++; 15031da177e4SLinus Torvalds TCP_SKB_CB(buff)->end_seq = tp->write_seq; 15041da177e4SLinus Torvalds tp->snd_nxt = tp->write_seq; 15051da177e4SLinus Torvalds tp->pushed_seq = tp->write_seq; 15061da177e4SLinus Torvalds tcp_ca_init(tp); 15071da177e4SLinus Torvalds 15081da177e4SLinus Torvalds /* Send it off. */ 15091da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 15101da177e4SLinus Torvalds tp->retrans_stamp = TCP_SKB_CB(buff)->when; 15111da177e4SLinus Torvalds skb_header_release(buff); 15121da177e4SLinus Torvalds __skb_queue_tail(&sk->sk_write_queue, buff); 15131da177e4SLinus Torvalds sk_charge_skb(sk, buff); 15141da177e4SLinus Torvalds tp->packets_out += tcp_skb_pcount(buff); 15151da177e4SLinus Torvalds tcp_transmit_skb(sk, skb_clone(buff, GFP_KERNEL)); 15161da177e4SLinus Torvalds TCP_INC_STATS(TCP_MIB_ACTIVEOPENS); 15171da177e4SLinus Torvalds 15181da177e4SLinus Torvalds /* Timer for repeating the SYN until an answer. */ 15191da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto); 15201da177e4SLinus Torvalds return 0; 15211da177e4SLinus Torvalds } 15221da177e4SLinus Torvalds 15231da177e4SLinus Torvalds /* Send out a delayed ack, the caller does the policy checking 15241da177e4SLinus Torvalds * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() 15251da177e4SLinus Torvalds * for details. 15261da177e4SLinus Torvalds */ 15271da177e4SLinus Torvalds void tcp_send_delayed_ack(struct sock *sk) 15281da177e4SLinus Torvalds { 15291da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 15301da177e4SLinus Torvalds int ato = tp->ack.ato; 15311da177e4SLinus Torvalds unsigned long timeout; 15321da177e4SLinus Torvalds 15331da177e4SLinus Torvalds if (ato > TCP_DELACK_MIN) { 15341da177e4SLinus Torvalds int max_ato = HZ/2; 15351da177e4SLinus Torvalds 15361da177e4SLinus Torvalds if (tp->ack.pingpong || (tp->ack.pending&TCP_ACK_PUSHED)) 15371da177e4SLinus Torvalds max_ato = TCP_DELACK_MAX; 15381da177e4SLinus Torvalds 15391da177e4SLinus Torvalds /* Slow path, intersegment interval is "high". */ 15401da177e4SLinus Torvalds 15411da177e4SLinus Torvalds /* If some rtt estimate is known, use it to bound delayed ack. 15421da177e4SLinus Torvalds * Do not use tp->rto here, use results of rtt measurements 15431da177e4SLinus Torvalds * directly. 15441da177e4SLinus Torvalds */ 15451da177e4SLinus Torvalds if (tp->srtt) { 15461da177e4SLinus Torvalds int rtt = max(tp->srtt>>3, TCP_DELACK_MIN); 15471da177e4SLinus Torvalds 15481da177e4SLinus Torvalds if (rtt < max_ato) 15491da177e4SLinus Torvalds max_ato = rtt; 15501da177e4SLinus Torvalds } 15511da177e4SLinus Torvalds 15521da177e4SLinus Torvalds ato = min(ato, max_ato); 15531da177e4SLinus Torvalds } 15541da177e4SLinus Torvalds 15551da177e4SLinus Torvalds /* Stay within the limit we were given */ 15561da177e4SLinus Torvalds timeout = jiffies + ato; 15571da177e4SLinus Torvalds 15581da177e4SLinus Torvalds /* Use new timeout only if there wasn't a older one earlier. */ 15591da177e4SLinus Torvalds if (tp->ack.pending&TCP_ACK_TIMER) { 15601da177e4SLinus Torvalds /* If delack timer was blocked or is about to expire, 15611da177e4SLinus Torvalds * send ACK now. 15621da177e4SLinus Torvalds */ 15631da177e4SLinus Torvalds if (tp->ack.blocked || time_before_eq(tp->ack.timeout, jiffies+(ato>>2))) { 15641da177e4SLinus Torvalds tcp_send_ack(sk); 15651da177e4SLinus Torvalds return; 15661da177e4SLinus Torvalds } 15671da177e4SLinus Torvalds 15681da177e4SLinus Torvalds if (!time_before(timeout, tp->ack.timeout)) 15691da177e4SLinus Torvalds timeout = tp->ack.timeout; 15701da177e4SLinus Torvalds } 15711da177e4SLinus Torvalds tp->ack.pending |= TCP_ACK_SCHED|TCP_ACK_TIMER; 15721da177e4SLinus Torvalds tp->ack.timeout = timeout; 15731da177e4SLinus Torvalds sk_reset_timer(sk, &tp->delack_timer, timeout); 15741da177e4SLinus Torvalds } 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds /* This routine sends an ack and also updates the window. */ 15771da177e4SLinus Torvalds void tcp_send_ack(struct sock *sk) 15781da177e4SLinus Torvalds { 15791da177e4SLinus Torvalds /* If we have been reset, we may not send again. */ 15801da177e4SLinus Torvalds if (sk->sk_state != TCP_CLOSE) { 15811da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 15821da177e4SLinus Torvalds struct sk_buff *buff; 15831da177e4SLinus Torvalds 15841da177e4SLinus Torvalds /* We are not putting this on the write queue, so 15851da177e4SLinus Torvalds * tcp_transmit_skb() will set the ownership to this 15861da177e4SLinus Torvalds * sock. 15871da177e4SLinus Torvalds */ 15881da177e4SLinus Torvalds buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 15891da177e4SLinus Torvalds if (buff == NULL) { 15901da177e4SLinus Torvalds tcp_schedule_ack(tp); 15911da177e4SLinus Torvalds tp->ack.ato = TCP_ATO_MIN; 15921da177e4SLinus Torvalds tcp_reset_xmit_timer(sk, TCP_TIME_DACK, TCP_DELACK_MAX); 15931da177e4SLinus Torvalds return; 15941da177e4SLinus Torvalds } 15951da177e4SLinus Torvalds 15961da177e4SLinus Torvalds /* Reserve space for headers and prepare control bits. */ 15971da177e4SLinus Torvalds skb_reserve(buff, MAX_TCP_HEADER); 15981da177e4SLinus Torvalds buff->csum = 0; 15991da177e4SLinus Torvalds TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK; 16001da177e4SLinus Torvalds TCP_SKB_CB(buff)->sacked = 0; 16011da177e4SLinus Torvalds skb_shinfo(buff)->tso_segs = 1; 16021da177e4SLinus Torvalds skb_shinfo(buff)->tso_size = 0; 16031da177e4SLinus Torvalds 16041da177e4SLinus Torvalds /* Send it off, this clears delayed acks for us. */ 16051da177e4SLinus Torvalds TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk, tp); 16061da177e4SLinus Torvalds TCP_SKB_CB(buff)->when = tcp_time_stamp; 16071da177e4SLinus Torvalds tcp_transmit_skb(sk, buff); 16081da177e4SLinus Torvalds } 16091da177e4SLinus Torvalds } 16101da177e4SLinus Torvalds 16111da177e4SLinus Torvalds /* This routine sends a packet with an out of date sequence 16121da177e4SLinus Torvalds * number. It assumes the other end will try to ack it. 16131da177e4SLinus Torvalds * 16141da177e4SLinus Torvalds * Question: what should we make while urgent mode? 16151da177e4SLinus Torvalds * 4.4BSD forces sending single byte of data. We cannot send 16161da177e4SLinus Torvalds * out of window data, because we have SND.NXT==SND.MAX... 16171da177e4SLinus Torvalds * 16181da177e4SLinus Torvalds * Current solution: to send TWO zero-length segments in urgent mode: 16191da177e4SLinus Torvalds * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is 16201da177e4SLinus Torvalds * out-of-date with SND.UNA-1 to probe window. 16211da177e4SLinus Torvalds */ 16221da177e4SLinus Torvalds static int tcp_xmit_probe_skb(struct sock *sk, int urgent) 16231da177e4SLinus Torvalds { 16241da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 16251da177e4SLinus Torvalds struct sk_buff *skb; 16261da177e4SLinus Torvalds 16271da177e4SLinus Torvalds /* We don't queue it, tcp_transmit_skb() sets ownership. */ 16281da177e4SLinus Torvalds skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); 16291da177e4SLinus Torvalds if (skb == NULL) 16301da177e4SLinus Torvalds return -1; 16311da177e4SLinus Torvalds 16321da177e4SLinus Torvalds /* Reserve space for headers and set control bits. */ 16331da177e4SLinus Torvalds skb_reserve(skb, MAX_TCP_HEADER); 16341da177e4SLinus Torvalds skb->csum = 0; 16351da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK; 16361da177e4SLinus Torvalds TCP_SKB_CB(skb)->sacked = urgent; 16371da177e4SLinus Torvalds skb_shinfo(skb)->tso_segs = 1; 16381da177e4SLinus Torvalds skb_shinfo(skb)->tso_size = 0; 16391da177e4SLinus Torvalds 16401da177e4SLinus Torvalds /* Use a previous sequence. This should cause the other 16411da177e4SLinus Torvalds * end to send an ack. Don't queue or clone SKB, just 16421da177e4SLinus Torvalds * send it. 16431da177e4SLinus Torvalds */ 16441da177e4SLinus Torvalds TCP_SKB_CB(skb)->seq = urgent ? tp->snd_una : tp->snd_una - 1; 16451da177e4SLinus Torvalds TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; 16461da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 16471da177e4SLinus Torvalds return tcp_transmit_skb(sk, skb); 16481da177e4SLinus Torvalds } 16491da177e4SLinus Torvalds 16501da177e4SLinus Torvalds int tcp_write_wakeup(struct sock *sk) 16511da177e4SLinus Torvalds { 16521da177e4SLinus Torvalds if (sk->sk_state != TCP_CLOSE) { 16531da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 16541da177e4SLinus Torvalds struct sk_buff *skb; 16551da177e4SLinus Torvalds 16561da177e4SLinus Torvalds if ((skb = sk->sk_send_head) != NULL && 16571da177e4SLinus Torvalds before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd)) { 16581da177e4SLinus Torvalds int err; 16591da177e4SLinus Torvalds unsigned int mss = tcp_current_mss(sk, 0); 16601da177e4SLinus Torvalds unsigned int seg_size = tp->snd_una+tp->snd_wnd-TCP_SKB_CB(skb)->seq; 16611da177e4SLinus Torvalds 16621da177e4SLinus Torvalds if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) 16631da177e4SLinus Torvalds tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; 16641da177e4SLinus Torvalds 16651da177e4SLinus Torvalds /* We are probing the opening of a window 16661da177e4SLinus Torvalds * but the window size is != 0 16671da177e4SLinus Torvalds * must have been a result SWS avoidance ( sender ) 16681da177e4SLinus Torvalds */ 16691da177e4SLinus Torvalds if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || 16701da177e4SLinus Torvalds skb->len > mss) { 16711da177e4SLinus Torvalds seg_size = min(seg_size, mss); 16721da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 16731da177e4SLinus Torvalds if (tcp_fragment(sk, skb, seg_size)) 16741da177e4SLinus Torvalds return -1; 16751da177e4SLinus Torvalds /* SWS override triggered forced fragmentation. 16761da177e4SLinus Torvalds * Disable TSO, the connection is too sick. */ 16771da177e4SLinus Torvalds if (sk->sk_route_caps & NETIF_F_TSO) { 16781da177e4SLinus Torvalds sock_set_flag(sk, SOCK_NO_LARGESEND); 16791da177e4SLinus Torvalds sk->sk_route_caps &= ~NETIF_F_TSO; 16801da177e4SLinus Torvalds tp->mss_cache = tp->mss_cache_std; 16811da177e4SLinus Torvalds } 16821da177e4SLinus Torvalds } else if (!tcp_skb_pcount(skb)) 1683d5ac99a6SDavid S. Miller tcp_set_skb_tso_segs(sk, skb); 16841da177e4SLinus Torvalds 16851da177e4SLinus Torvalds TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 16861da177e4SLinus Torvalds TCP_SKB_CB(skb)->when = tcp_time_stamp; 16871da177e4SLinus Torvalds tcp_tso_set_push(skb); 16881da177e4SLinus Torvalds err = tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)); 16891da177e4SLinus Torvalds if (!err) { 16901da177e4SLinus Torvalds update_send_head(sk, tp, skb); 16911da177e4SLinus Torvalds } 16921da177e4SLinus Torvalds return err; 16931da177e4SLinus Torvalds } else { 16941da177e4SLinus Torvalds if (tp->urg_mode && 16951da177e4SLinus Torvalds between(tp->snd_up, tp->snd_una+1, tp->snd_una+0xFFFF)) 16961da177e4SLinus Torvalds tcp_xmit_probe_skb(sk, TCPCB_URG); 16971da177e4SLinus Torvalds return tcp_xmit_probe_skb(sk, 0); 16981da177e4SLinus Torvalds } 16991da177e4SLinus Torvalds } 17001da177e4SLinus Torvalds return -1; 17011da177e4SLinus Torvalds } 17021da177e4SLinus Torvalds 17031da177e4SLinus Torvalds /* A window probe timeout has occurred. If window is not closed send 17041da177e4SLinus Torvalds * a partial packet else a zero probe. 17051da177e4SLinus Torvalds */ 17061da177e4SLinus Torvalds void tcp_send_probe0(struct sock *sk) 17071da177e4SLinus Torvalds { 17081da177e4SLinus Torvalds struct tcp_sock *tp = tcp_sk(sk); 17091da177e4SLinus Torvalds int err; 17101da177e4SLinus Torvalds 17111da177e4SLinus Torvalds err = tcp_write_wakeup(sk); 17121da177e4SLinus Torvalds 17131da177e4SLinus Torvalds if (tp->packets_out || !sk->sk_send_head) { 17141da177e4SLinus Torvalds /* Cancel probe timer, if it is not required. */ 17151da177e4SLinus Torvalds tp->probes_out = 0; 17161da177e4SLinus Torvalds tp->backoff = 0; 17171da177e4SLinus Torvalds return; 17181da177e4SLinus Torvalds } 17191da177e4SLinus Torvalds 17201da177e4SLinus Torvalds if (err <= 0) { 17211da177e4SLinus Torvalds if (tp->backoff < sysctl_tcp_retries2) 17221da177e4SLinus Torvalds tp->backoff++; 17231da177e4SLinus Torvalds tp->probes_out++; 17241da177e4SLinus Torvalds tcp_reset_xmit_timer (sk, TCP_TIME_PROBE0, 17251da177e4SLinus Torvalds min(tp->rto << tp->backoff, TCP_RTO_MAX)); 17261da177e4SLinus Torvalds } else { 17271da177e4SLinus Torvalds /* If packet was not sent due to local congestion, 17281da177e4SLinus Torvalds * do not backoff and do not remember probes_out. 17291da177e4SLinus Torvalds * Let local senders to fight for local resources. 17301da177e4SLinus Torvalds * 17311da177e4SLinus Torvalds * Use accumulated backoff yet. 17321da177e4SLinus Torvalds */ 17331da177e4SLinus Torvalds if (!tp->probes_out) 17341da177e4SLinus Torvalds tp->probes_out=1; 17351da177e4SLinus Torvalds tcp_reset_xmit_timer (sk, TCP_TIME_PROBE0, 17361da177e4SLinus Torvalds min(tp->rto << tp->backoff, TCP_RESOURCE_PROBE_INTERVAL)); 17371da177e4SLinus Torvalds } 17381da177e4SLinus Torvalds } 17391da177e4SLinus Torvalds 17401da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_connect); 17411da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_make_synack); 17421da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_simple_retransmit); 17431da177e4SLinus Torvalds EXPORT_SYMBOL(tcp_sync_mss); 1744