| /* |
| * INET An implementation of the TCP/IP protocol suite for the LINUX |
| * operating system. INET is implemented using the BSD Socket |
| * interface as the means of communication with the user level. |
| * |
| * Implementation of the Transmission Control Protocol(TCP). |
| * |
| * Version: $Id: tcp_output.c,v 1.146 2002/02/01 22:01:04 davem Exp $ |
| * |
| * Authors: Ross Biro |
| * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
| * Mark Evans, <evansmp@uhura.aston.ac.uk> |
| * Corey Minyard <wf-rch!minyard@relay.EU.net> |
| * Florian La Roche, <flla@stud.uni-sb.de> |
| * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> |
| * Linus Torvalds, <torvalds@cs.helsinki.fi> |
| * Alan Cox, <gw4pts@gw4pts.ampr.org> |
| * Matthew Dillon, <dillon@apollo.west.oic.com> |
| * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| * Jorge Cwik, <jorge@laser.satlink.net> |
| */ |
| |
| /* |
| * Changes: Pedro Roque : Retransmit queue handled by TCP. |
| * : Fragmentation on mtu decrease |
| * : Segment collapse on retransmit |
| * : AF independence |
| * |
| * Linus Torvalds : send_delayed_ack |
| * David S. Miller : Charge memory using the right skb |
| * during syn/ack processing. |
| * David S. Miller : Output engine completely rewritten. |
| * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. |
| * Cacophonix Gaul : draft-minshall-nagle-01 |
| * J Hadi Salim : ECN support |
| * |
| */ |
| |
| #include <net/tcp.h> |
| |
| #include <linux/compiler.h> |
| #include <linux/module.h> |
| #include <linux/smp_lock.h> |
| |
| /* People can turn this off for buggy TCP's found in printers etc. */ |
| int sysctl_tcp_retrans_collapse = 1; |
| |
| /* This limits the percentage of the congestion window which we |
| * will allow a single TSO frame to consume. Building TSO frames |
| * which are too large can cause TCP streams to be bursty. |
| */ |
| int sysctl_tcp_tso_win_divisor = 3; |
| |
| static inline void update_send_head(struct sock *sk, struct tcp_sock *tp, |
| struct sk_buff *skb) |
| { |
| sk->sk_send_head = skb->next; |
| if (sk->sk_send_head == (struct sk_buff *)&sk->sk_write_queue) |
| sk->sk_send_head = NULL; |
| tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; |
| tcp_packets_out_inc(sk, tp, skb); |
| } |
| |
| /* SND.NXT, if window was not shrunk. |
| * If window has been shrunk, what should we make? It is not clear at all. |
| * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( |
| * Anything in between SND.UNA...SND.UNA+SND.WND also can be already |
| * invalid. OK, let's make this for now: |
| */ |
| static inline __u32 tcp_acceptable_seq(struct sock *sk, struct tcp_sock *tp) |
| { |
| if (!before(tp->snd_una+tp->snd_wnd, tp->snd_nxt)) |
| return tp->snd_nxt; |
| else |
| return tp->snd_una+tp->snd_wnd; |
| } |
| |
| /* Calculate mss to advertise in SYN segment. |
| * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: |
| * |
| * 1. It is independent of path mtu. |
| * 2. Ideally, it is maximal possible segment size i.e. 65535-40. |
| * 3. For IPv4 it is reasonable to calculate it from maximal MTU of |
| * attached devices, because some buggy hosts are confused by |
| * large MSS. |
| * 4. We do not make 3, we advertise MSS, calculated from first |
| * hop device mtu, but allow to raise it to ip_rt_min_advmss. |
| * This may be overridden via information stored in routing table. |
| * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, |
| * probably even Jumbo". |
| */ |
| static __u16 tcp_advertise_mss(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct dst_entry *dst = __sk_dst_get(sk); |
| int mss = tp->advmss; |
| |
| if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { |
| mss = dst_metric(dst, RTAX_ADVMSS); |
| tp->advmss = mss; |
| } |
| |
| return (__u16)mss; |
| } |
| |
| /* RFC2861. Reset CWND after idle period longer RTO to "restart window". |
| * This is the first part of cwnd validation mechanism. */ |
| static void tcp_cwnd_restart(struct sock *sk, struct dst_entry *dst) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| s32 delta = tcp_time_stamp - tp->lsndtime; |
| u32 restart_cwnd = tcp_init_cwnd(tp, dst); |
| u32 cwnd = tp->snd_cwnd; |
| |
| tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
| |
| tp->snd_ssthresh = tcp_current_ssthresh(sk); |
| restart_cwnd = min(restart_cwnd, cwnd); |
| |
| while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
| cwnd >>= 1; |
| tp->snd_cwnd = max(cwnd, restart_cwnd); |
| tp->snd_cwnd_stamp = tcp_time_stamp; |
| tp->snd_cwnd_used = 0; |
| } |
| |
| static inline void tcp_event_data_sent(struct tcp_sock *tp, |
| struct sk_buff *skb, struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| const u32 now = tcp_time_stamp; |
| |
| if (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto) |
| tcp_cwnd_restart(sk, __sk_dst_get(sk)); |
| |
| tp->lsndtime = now; |
| |
| /* If it is a reply for ato after last received |
| * packet, enter pingpong mode. |
| */ |
| if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
| icsk->icsk_ack.pingpong = 1; |
| } |
| |
| static __inline__ void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
| { |
| tcp_dec_quickack_mode(sk, pkts); |
| inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); |
| } |
| |
| /* Determine a window scaling and initial window to offer. |
| * Based on the assumption that the given amount of space |
| * will be offered. Store the results in the tp structure. |
| * NOTE: for smooth operation initial space offering should |
| * be a multiple of mss if possible. We assume here that mss >= 1. |
| * This MUST be enforced by all callers. |
| */ |
| void tcp_select_initial_window(int __space, __u32 mss, |
| __u32 *rcv_wnd, __u32 *window_clamp, |
| int wscale_ok, __u8 *rcv_wscale) |
| { |
| unsigned int space = (__space < 0 ? 0 : __space); |
| |
| /* If no clamp set the clamp to the max possible scaled window */ |
| if (*window_clamp == 0) |
| (*window_clamp) = (65535 << 14); |
| space = min(*window_clamp, space); |
| |
| /* Quantize space offering to a multiple of mss if possible. */ |
| if (space > mss) |
| space = (space / mss) * mss; |
| |
| /* NOTE: offering an initial window larger than 32767 |
| * will break some buggy TCP stacks. We try to be nice. |
| * If we are not window scaling, then this truncates |
| * our initial window offering to 32k. There should also |
| * be a sysctl option to stop being nice. |
| */ |
| (*rcv_wnd) = min(space, MAX_TCP_WINDOW); |
| (*rcv_wscale) = 0; |
| if (wscale_ok) { |
| /* Set window scaling on max possible window |
| * See RFC1323 for an explanation of the limit to 14 |
| */ |
| space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); |
| while (space > 65535 && (*rcv_wscale) < 14) { |
| space >>= 1; |
| (*rcv_wscale)++; |
| } |
| } |
| |
| /* Set initial window to value enough for senders, |
| * following RFC1414. Senders, not following this RFC, |
| * will be satisfied with 2. |
| */ |
| if (mss > (1<<*rcv_wscale)) { |
| int init_cwnd = 4; |
| if (mss > 1460*3) |
| init_cwnd = 2; |
| else if (mss > 1460) |
| init_cwnd = 3; |
| if (*rcv_wnd > init_cwnd*mss) |
| *rcv_wnd = init_cwnd*mss; |
| } |
| |
| /* Set the clamp no higher than max representable value */ |
| (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); |
| } |
| |
| /* Chose a new window to advertise, update state in tcp_sock for the |
| * socket, and return result with RFC1323 scaling applied. The return |
| * value can be stuffed directly into th->window for an outgoing |
| * frame. |
| */ |
| static __inline__ u16 tcp_select_window(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| u32 cur_win = tcp_receive_window(tp); |
| u32 new_win = __tcp_select_window(sk); |
| |
| /* Never shrink the offered window */ |
| if(new_win < cur_win) { |
| /* Danger Will Robinson! |
| * Don't update rcv_wup/rcv_wnd here or else |
| * we will not be able to advertise a zero |
| * window in time. --DaveM |
| * |
| * Relax Will Robinson. |
| */ |
| new_win = cur_win; |
| } |
| tp->rcv_wnd = new_win; |
| tp->rcv_wup = tp->rcv_nxt; |
| |
| /* Make sure we do not exceed the maximum possible |
| * scaled window. |
| */ |
| if (!tp->rx_opt.rcv_wscale) |
| new_win = min(new_win, MAX_TCP_WINDOW); |
| else |
| new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); |
| |
| /* RFC1323 scaling applied */ |
| new_win >>= tp->rx_opt.rcv_wscale; |
| |
| /* If we advertise zero window, disable fast path. */ |
| if (new_win == 0) |
| tp->pred_flags = 0; |
| |
| return new_win; |
| } |
| |
| |
| /* This routine actually transmits TCP packets queued in by |
| * tcp_do_sendmsg(). This is used by both the initial |
| * transmission and possible later retransmissions. |
| * All SKB's seen here are completely headerless. It is our |
| * job to build the TCP header, and pass the packet down to |
| * IP so it can do the same plus pass the packet off to the |
| * device. |
| * |
| * We are working here with either a clone of the original |
| * SKB, or a fresh unique copy made by the retransmit engine. |
| */ |
| static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb) |
| { |
| if (skb != NULL) { |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| struct inet_sock *inet = inet_sk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); |
| int tcp_header_size = tp->tcp_header_len; |
| struct tcphdr *th; |
| int sysctl_flags; |
| int err; |
| |
| BUG_ON(!tcp_skb_pcount(skb)); |
| |
| #define SYSCTL_FLAG_TSTAMPS 0x1 |
| #define SYSCTL_FLAG_WSCALE 0x2 |
| #define SYSCTL_FLAG_SACK 0x4 |
| |
| /* If congestion control is doing timestamping */ |
| if (icsk->icsk_ca_ops->rtt_sample) |
| __net_timestamp(skb); |
| |
| sysctl_flags = 0; |
| if (tcb->flags & TCPCB_FLAG_SYN) { |
| tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS; |
| if(sysctl_tcp_timestamps) { |
| tcp_header_size += TCPOLEN_TSTAMP_ALIGNED; |
| sysctl_flags |= SYSCTL_FLAG_TSTAMPS; |
| } |
| if(sysctl_tcp_window_scaling) { |
| tcp_header_size += TCPOLEN_WSCALE_ALIGNED; |
| sysctl_flags |= SYSCTL_FLAG_WSCALE; |
| } |
| if(sysctl_tcp_sack) { |
| sysctl_flags |= SYSCTL_FLAG_SACK; |
| if(!(sysctl_flags & SYSCTL_FLAG_TSTAMPS)) |
| tcp_header_size += TCPOLEN_SACKPERM_ALIGNED; |
| } |
| } else if (tp->rx_opt.eff_sacks) { |
| /* A SACK is 2 pad bytes, a 2 byte header, plus |
| * 2 32-bit sequence numbers for each SACK block. |
| */ |
| tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED + |
| (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); |
| } |
| |
| if (tcp_packets_in_flight(tp) == 0) |
| tcp_ca_event(sk, CA_EVENT_TX_START); |
| |
| th = (struct tcphdr *) skb_push(skb, tcp_header_size); |
| skb->h.th = th; |
| skb_set_owner_w(skb, sk); |
| |
| /* Build TCP header and checksum it. */ |
| th->source = inet->sport; |
| th->dest = inet->dport; |
| th->seq = htonl(tcb->seq); |
| th->ack_seq = htonl(tp->rcv_nxt); |
| *(((__u16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | tcb->flags); |
| if (tcb->flags & TCPCB_FLAG_SYN) { |
| /* RFC1323: The window in SYN & SYN/ACK segments |
| * is never scaled. |
| */ |
| th->window = htons(tp->rcv_wnd); |
| } else { |
| th->window = htons(tcp_select_window(sk)); |
| } |
| th->check = 0; |
| th->urg_ptr = 0; |
| |
| if (tp->urg_mode && |
| between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF)) { |
| th->urg_ptr = htons(tp->snd_up-tcb->seq); |
| th->urg = 1; |
| } |
| |
| if (tcb->flags & TCPCB_FLAG_SYN) { |
| tcp_syn_build_options((__u32 *)(th + 1), |
| tcp_advertise_mss(sk), |
| (sysctl_flags & SYSCTL_FLAG_TSTAMPS), |
| (sysctl_flags & SYSCTL_FLAG_SACK), |
| (sysctl_flags & SYSCTL_FLAG_WSCALE), |
| tp->rx_opt.rcv_wscale, |
| tcb->when, |
| tp->rx_opt.ts_recent); |
| } else { |
| tcp_build_and_update_options((__u32 *)(th + 1), |
| tp, tcb->when); |
| |
| TCP_ECN_send(sk, tp, skb, tcp_header_size); |
| } |
| tp->af_specific->send_check(sk, th, skb->len, skb); |
| |
| if (tcb->flags & TCPCB_FLAG_ACK) |
| tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); |
| |
| if (skb->len != tcp_header_size) |
| tcp_event_data_sent(tp, skb, sk); |
| |
| TCP_INC_STATS(TCP_MIB_OUTSEGS); |
| |
| err = tp->af_specific->queue_xmit(skb, 0); |
| if (err <= 0) |
| return err; |
| |
| tcp_enter_cwr(sk); |
| |
| /* NET_XMIT_CN is special. It does not guarantee, |
| * that this packet is lost. It tells that device |
| * is about to start to drop packets or already |
| * drops some packets of the same priority and |
| * invokes us to send less aggressively. |
| */ |
| return err == NET_XMIT_CN ? 0 : err; |
| } |
| return -ENOBUFS; |
| #undef SYSCTL_FLAG_TSTAMPS |
| #undef SYSCTL_FLAG_WSCALE |
| #undef SYSCTL_FLAG_SACK |
| } |
| |
| |
| /* This routine just queue's the buffer |
| * |
| * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, |
| * otherwise socket can stall. |
| */ |
| static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| /* Advance write_seq and place onto the write_queue. */ |
| tp->write_seq = TCP_SKB_CB(skb)->end_seq; |
| skb_header_release(skb); |
| __skb_queue_tail(&sk->sk_write_queue, skb); |
| sk_charge_skb(sk, skb); |
| |
| /* Queue it, remembering where we must start sending. */ |
| if (sk->sk_send_head == NULL) |
| sk->sk_send_head = skb; |
| } |
| |
| static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) |
| { |
| if (skb->len <= mss_now || |
| !(sk->sk_route_caps & NETIF_F_TSO)) { |
| /* Avoid the costly divide in the normal |
| * non-TSO case. |
| */ |
| skb_shinfo(skb)->tso_segs = 1; |
| skb_shinfo(skb)->tso_size = 0; |
| } else { |
| unsigned int factor; |
| |
| factor = skb->len + (mss_now - 1); |
| factor /= mss_now; |
| skb_shinfo(skb)->tso_segs = factor; |
| skb_shinfo(skb)->tso_size = mss_now; |
| } |
| } |
| |
| /* Function to create two new TCP segments. Shrinks the given segment |
| * to the specified size and appends a new segment with the rest of the |
| * packet to the list. This won't be called frequently, I hope. |
| * Remember, these are still headerless SKBs at this point. |
| */ |
| static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss_now) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *buff; |
| int nsize; |
| u16 flags; |
| |
| nsize = skb_headlen(skb) - len; |
| if (nsize < 0) |
| nsize = 0; |
| |
| if (skb_cloned(skb) && |
| skb_is_nonlinear(skb) && |
| pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
| return -ENOMEM; |
| |
| /* Get a new skb... force flag on. */ |
| buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); |
| if (buff == NULL) |
| return -ENOMEM; /* We'll just try again later. */ |
| sk_charge_skb(sk, buff); |
| |
| /* Correct the sequence numbers. */ |
| TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; |
| TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; |
| |
| /* PSH and FIN should only be set in the second packet. */ |
| flags = TCP_SKB_CB(skb)->flags; |
| TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); |
| TCP_SKB_CB(buff)->flags = flags; |
| TCP_SKB_CB(buff)->sacked = |
| (TCP_SKB_CB(skb)->sacked & |
| (TCPCB_LOST | TCPCB_EVER_RETRANS | TCPCB_AT_TAIL)); |
| TCP_SKB_CB(skb)->sacked &= ~TCPCB_AT_TAIL; |
| |
| if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_HW) { |
| /* Copy and checksum data tail into the new buffer. */ |
| buff->csum = csum_partial_copy_nocheck(skb->data + len, skb_put(buff, nsize), |
| nsize, 0); |
| |
| skb_trim(skb, len); |
| |
| skb->csum = csum_block_sub(skb->csum, buff->csum, len); |
| } else { |
| skb->ip_summed = CHECKSUM_HW; |
| skb_split(skb, buff, len); |
| } |
| |
| buff->ip_summed = skb->ip_summed; |
| |
| /* Looks stupid, but our code really uses when of |
| * skbs, which it never sent before. --ANK |
| */ |
| TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; |
| buff->tstamp = skb->tstamp; |
| |
| if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { |
| tp->lost_out -= tcp_skb_pcount(skb); |
| tp->left_out -= tcp_skb_pcount(skb); |
| } |
| |
| /* Fix up tso_factor for both original and new SKB. */ |
| tcp_set_skb_tso_segs(sk, skb, mss_now); |
| tcp_set_skb_tso_segs(sk, buff, mss_now); |
| |
| if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { |
| tp->lost_out += tcp_skb_pcount(skb); |
| tp->left_out += tcp_skb_pcount(skb); |
| } |
| |
| if (TCP_SKB_CB(buff)->sacked&TCPCB_LOST) { |
| tp->lost_out += tcp_skb_pcount(buff); |
| tp->left_out += tcp_skb_pcount(buff); |
| } |
| |
| /* Link BUFF into the send queue. */ |
| skb_header_release(buff); |
| __skb_append(skb, buff, &sk->sk_write_queue); |
| |
| return 0; |
| } |
| |
| /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c |
| * eventually). The difference is that pulled data not copied, but |
| * immediately discarded. |
| */ |
| static unsigned char *__pskb_trim_head(struct sk_buff *skb, int len) |
| { |
| int i, k, eat; |
| |
| eat = len; |
| k = 0; |
| for (i=0; i<skb_shinfo(skb)->nr_frags; i++) { |
| if (skb_shinfo(skb)->frags[i].size <= eat) { |
| put_page(skb_shinfo(skb)->frags[i].page); |
| eat -= skb_shinfo(skb)->frags[i].size; |
| } else { |
| skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; |
| if (eat) { |
| skb_shinfo(skb)->frags[k].page_offset += eat; |
| skb_shinfo(skb)->frags[k].size -= eat; |
| eat = 0; |
| } |
| k++; |
| } |
| } |
| skb_shinfo(skb)->nr_frags = k; |
| |
| skb->tail = skb->data; |
| skb->data_len -= len; |
| skb->len = skb->data_len; |
| return skb->tail; |
| } |
| |
| int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
| { |
| if (skb_cloned(skb) && |
| pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
| return -ENOMEM; |
| |
| if (len <= skb_headlen(skb)) { |
| __skb_pull(skb, len); |
| } else { |
| if (__pskb_trim_head(skb, len-skb_headlen(skb)) == NULL) |
| return -ENOMEM; |
| } |
| |
| TCP_SKB_CB(skb)->seq += len; |
| skb->ip_summed = CHECKSUM_HW; |
| |
| skb->truesize -= len; |
| sk->sk_wmem_queued -= len; |
| sk->sk_forward_alloc += len; |
| sock_set_flag(sk, SOCK_QUEUE_SHRUNK); |
| |
| /* Any change of skb->len requires recalculation of tso |
| * factor and mss. |
| */ |
| if (tcp_skb_pcount(skb) > 1) |
| tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1)); |
| |
| return 0; |
| } |
| |
| /* This function synchronize snd mss to current pmtu/exthdr set. |
| |
| tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts |
| for TCP options, but includes only bare TCP header. |
| |
| tp->rx_opt.mss_clamp is mss negotiated at connection setup. |
| It is minumum of user_mss and mss received with SYN. |
| It also does not include TCP options. |
| |
| tp->pmtu_cookie is last pmtu, seen by this function. |
| |
| tp->mss_cache is current effective sending mss, including |
| all tcp options except for SACKs. It is evaluated, |
| taking into account current pmtu, but never exceeds |
| tp->rx_opt.mss_clamp. |
| |
| NOTE1. rfc1122 clearly states that advertised MSS |
| DOES NOT include either tcp or ip options. |
| |
| NOTE2. tp->pmtu_cookie and tp->mss_cache are READ ONLY outside |
| this function. --ANK (980731) |
| */ |
| |
| unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| int mss_now; |
| |
| /* Calculate base mss without TCP options: |
| It is MMS_S - sizeof(tcphdr) of rfc1122 |
| */ |
| mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct tcphdr); |
| |
| /* Clamp it (mss_clamp does not include tcp options) */ |
| if (mss_now > tp->rx_opt.mss_clamp) |
| mss_now = tp->rx_opt.mss_clamp; |
| |
| /* Now subtract optional transport overhead */ |
| mss_now -= tp->ext_header_len; |
| |
| /* Then reserve room for full set of TCP options and 8 bytes of data */ |
| if (mss_now < 48) |
| mss_now = 48; |
| |
| /* Now subtract TCP options size, not including SACKs */ |
| mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); |
| |
| /* Bound mss with half of window */ |
| if (tp->max_window && mss_now > (tp->max_window>>1)) |
| mss_now = max((tp->max_window>>1), 68U - tp->tcp_header_len); |
| |
| /* And store cached results */ |
| tp->pmtu_cookie = pmtu; |
| tp->mss_cache = mss_now; |
| |
| return mss_now; |
| } |
| |
| /* Compute the current effective MSS, taking SACKs and IP options, |
| * and even PMTU discovery events into account. |
| * |
| * LARGESEND note: !urg_mode is overkill, only frames up to snd_up |
| * cannot be large. However, taking into account rare use of URG, this |
| * is not a big flaw. |
| */ |
| unsigned int tcp_current_mss(struct sock *sk, int large_allowed) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct dst_entry *dst = __sk_dst_get(sk); |
| u32 mss_now; |
| u16 xmit_size_goal; |
| int doing_tso = 0; |
| |
| mss_now = tp->mss_cache; |
| |
| if (large_allowed && |
| (sk->sk_route_caps & NETIF_F_TSO) && |
| !tp->urg_mode) |
| doing_tso = 1; |
| |
| if (dst) { |
| u32 mtu = dst_mtu(dst); |
| if (mtu != tp->pmtu_cookie) |
| mss_now = tcp_sync_mss(sk, mtu); |
| } |
| |
| if (tp->rx_opt.eff_sacks) |
| mss_now -= (TCPOLEN_SACK_BASE_ALIGNED + |
| (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); |
| |
| xmit_size_goal = mss_now; |
| |
| if (doing_tso) { |
| xmit_size_goal = 65535 - |
| tp->af_specific->net_header_len - |
| tp->ext_header_len - tp->tcp_header_len; |
| |
| if (tp->max_window && |
| (xmit_size_goal > (tp->max_window >> 1))) |
| xmit_size_goal = max((tp->max_window >> 1), |
| 68U - tp->tcp_header_len); |
| |
| xmit_size_goal -= (xmit_size_goal % mss_now); |
| } |
| tp->xmit_size_goal = xmit_size_goal; |
| |
| return mss_now; |
| } |
| |
| /* Congestion window validation. (RFC2861) */ |
| |
| static inline void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp) |
| { |
| __u32 packets_out = tp->packets_out; |
| |
| if (packets_out >= tp->snd_cwnd) { |
| /* Network is feed fully. */ |
| tp->snd_cwnd_used = 0; |
| tp->snd_cwnd_stamp = tcp_time_stamp; |
| } else { |
| /* Network starves. */ |
| if (tp->packets_out > tp->snd_cwnd_used) |
| tp->snd_cwnd_used = tp->packets_out; |
| |
| if ((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) |
| tcp_cwnd_application_limited(sk); |
| } |
| } |
| |
| static unsigned int tcp_window_allows(struct tcp_sock *tp, struct sk_buff *skb, unsigned int mss_now, unsigned int cwnd) |
| { |
| u32 window, cwnd_len; |
| |
| window = (tp->snd_una + tp->snd_wnd - TCP_SKB_CB(skb)->seq); |
| cwnd_len = mss_now * cwnd; |
| return min(window, cwnd_len); |
| } |
| |
| /* Can at least one segment of SKB be sent right now, according to the |
| * congestion window rules? If so, return how many segments are allowed. |
| */ |
| static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *skb) |
| { |
| u32 in_flight, cwnd; |
| |
| /* Don't be strict about the congestion window for the final FIN. */ |
| if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) |
| return 1; |
| |
| in_flight = tcp_packets_in_flight(tp); |
| cwnd = tp->snd_cwnd; |
| if (in_flight < cwnd) |
| return (cwnd - in_flight); |
| |
| return 0; |
| } |
| |
| /* This must be invoked the first time we consider transmitting |
| * SKB onto the wire. |
| */ |
| static inline int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) |
| { |
| int tso_segs = tcp_skb_pcount(skb); |
| |
| if (!tso_segs || |
| (tso_segs > 1 && |
| skb_shinfo(skb)->tso_size != mss_now)) { |
| tcp_set_skb_tso_segs(sk, skb, mss_now); |
| tso_segs = tcp_skb_pcount(skb); |
| } |
| return tso_segs; |
| } |
| |
| static inline int tcp_minshall_check(const struct tcp_sock *tp) |
| { |
| return after(tp->snd_sml,tp->snd_una) && |
| !after(tp->snd_sml, tp->snd_nxt); |
| } |
| |
| /* Return 0, if packet can be sent now without violation Nagle's rules: |
| * 1. It is full sized. |
| * 2. Or it contains FIN. (already checked by caller) |
| * 3. Or TCP_NODELAY was set. |
| * 4. Or TCP_CORK is not set, and all sent packets are ACKed. |
| * With Minshall's modification: all sent small packets are ACKed. |
| */ |
| |
| static inline int tcp_nagle_check(const struct tcp_sock *tp, |
| const struct sk_buff *skb, |
| unsigned mss_now, int nonagle) |
| { |
| return (skb->len < mss_now && |
| ((nonagle&TCP_NAGLE_CORK) || |
| (!nonagle && |
| tp->packets_out && |
| tcp_minshall_check(tp)))); |
| } |
| |
| /* Return non-zero if the Nagle test allows this packet to be |
| * sent now. |
| */ |
| static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, |
| unsigned int cur_mss, int nonagle) |
| { |
| /* Nagle rule does not apply to frames, which sit in the middle of the |
| * write_queue (they have no chances to get new data). |
| * |
| * This is implemented in the callers, where they modify the 'nonagle' |
| * argument based upon the location of SKB in the send queue. |
| */ |
| if (nonagle & TCP_NAGLE_PUSH) |
| return 1; |
| |
| /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
| if (tp->urg_mode || |
| (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) |
| return 1; |
| |
| if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) |
| return 1; |
| |
| return 0; |
| } |
| |
| /* Does at least the first segment of SKB fit into the send window? */ |
| static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, unsigned int cur_mss) |
| { |
| u32 end_seq = TCP_SKB_CB(skb)->end_seq; |
| |
| if (skb->len > cur_mss) |
| end_seq = TCP_SKB_CB(skb)->seq + cur_mss; |
| |
| return !after(end_seq, tp->snd_una + tp->snd_wnd); |
| } |
| |
| /* This checks if the data bearing packet SKB (usually sk->sk_send_head) |
| * should be put on the wire right now. If so, it returns the number of |
| * packets allowed by the congestion window. |
| */ |
| static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, |
| unsigned int cur_mss, int nonagle) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| unsigned int cwnd_quota; |
| |
| tcp_init_tso_segs(sk, skb, cur_mss); |
| |
| if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) |
| return 0; |
| |
| cwnd_quota = tcp_cwnd_test(tp, skb); |
| if (cwnd_quota && |
| !tcp_snd_wnd_test(tp, skb, cur_mss)) |
| cwnd_quota = 0; |
| |
| return cwnd_quota; |
| } |
| |
| static inline int tcp_skb_is_last(const struct sock *sk, |
| const struct sk_buff *skb) |
| { |
| return skb->next == (struct sk_buff *)&sk->sk_write_queue; |
| } |
| |
| int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp) |
| { |
| struct sk_buff *skb = sk->sk_send_head; |
| |
| return (skb && |
| tcp_snd_test(sk, skb, tcp_current_mss(sk, 1), |
| (tcp_skb_is_last(sk, skb) ? |
| TCP_NAGLE_PUSH : |
| tp->nonagle))); |
| } |
| |
| /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet |
| * which is put after SKB on the list. It is very much like |
| * tcp_fragment() except that it may make several kinds of assumptions |
| * in order to speed up the splitting operation. In particular, we |
| * know that all the data is in scatter-gather pages, and that the |
| * packet has never been sent out before (and thus is not cloned). |
| */ |
| static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, unsigned int mss_now) |
| { |
| struct sk_buff *buff; |
| int nlen = skb->len - len; |
| u16 flags; |
| |
| /* All of a TSO frame must be composed of paged data. */ |
| if (skb->len != skb->data_len) |
| return tcp_fragment(sk, skb, len, mss_now); |
| |
| buff = sk_stream_alloc_pskb(sk, 0, 0, GFP_ATOMIC); |
| if (unlikely(buff == NULL)) |
| return -ENOMEM; |
| |
| buff->truesize = nlen; |
| skb->truesize -= nlen; |
| |
| /* Correct the sequence numbers. */ |
| TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; |
| TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; |
| |
| /* PSH and FIN should only be set in the second packet. */ |
| flags = TCP_SKB_CB(skb)->flags; |
| TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); |
| TCP_SKB_CB(buff)->flags = flags; |
| |
| /* This packet was never sent out yet, so no SACK bits. */ |
| TCP_SKB_CB(buff)->sacked = 0; |
| |
| buff->ip_summed = skb->ip_summed = CHECKSUM_HW; |
| skb_split(skb, buff, len); |
| |
| /* Fix up tso_factor for both original and new SKB. */ |
| tcp_set_skb_tso_segs(sk, skb, mss_now); |
| tcp_set_skb_tso_segs(sk, buff, mss_now); |
| |
| /* Link BUFF into the send queue. */ |
| skb_header_release(buff); |
| __skb_append(skb, buff, &sk->sk_write_queue); |
| |
| return 0; |
| } |
| |
| /* Try to defer sending, if possible, in order to minimize the amount |
| * of TSO splitting we do. View it as a kind of TSO Nagle test. |
| * |
| * This algorithm is from John Heffner. |
| */ |
| static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) |
| { |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| u32 send_win, cong_win, limit, in_flight; |
| |
| if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) |
| return 0; |
| |
| if (icsk->icsk_ca_state != TCP_CA_Open) |
| return 0; |
| |
| in_flight = tcp_packets_in_flight(tp); |
| |
| BUG_ON(tcp_skb_pcount(skb) <= 1 || |
| (tp->snd_cwnd <= in_flight)); |
| |
| send_win = (tp->snd_una + tp->snd_wnd) - TCP_SKB_CB(skb)->seq; |
| |
| /* From in_flight test above, we know that cwnd > in_flight. */ |
| cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; |
| |
| limit = min(send_win, cong_win); |
| |
| if (sysctl_tcp_tso_win_divisor) { |
| u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
| |
| /* If at least some fraction of a window is available, |
| * just use it. |
| */ |
| chunk /= sysctl_tcp_tso_win_divisor; |
| if (limit >= chunk) |
| return 0; |
| } else { |
| /* Different approach, try not to defer past a single |
| * ACK. Receiver should ACK every other full sized |
| * frame, so if we have space for more than 3 frames |
| * then send now. |
| */ |
| if (limit > tcp_max_burst(tp) * tp->mss_cache) |
| return 0; |
| } |
| |
| /* Ok, it looks like it is advisable to defer. */ |
| return 1; |
| } |
| |
| /* This routine writes packets to the network. It advances the |
| * send_head. This happens as incoming acks open up the remote |
| * window for us. |
| * |
| * Returns 1, if no segments are in flight and we have queued segments, but |
| * cannot send anything now because of SWS or another problem. |
| */ |
| static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| unsigned int tso_segs, sent_pkts; |
| int cwnd_quota; |
| |
| /* If we are closed, the bytes will have to remain here. |
| * In time closedown will finish, we empty the write queue and all |
| * will be happy. |
| */ |
| if (unlikely(sk->sk_state == TCP_CLOSE)) |
| return 0; |
| |
| sent_pkts = 0; |
| while ((skb = sk->sk_send_head)) { |
| unsigned int limit; |
| |
| tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
| BUG_ON(!tso_segs); |
| |
| cwnd_quota = tcp_cwnd_test(tp, skb); |
| if (!cwnd_quota) |
| break; |
| |
| if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) |
| break; |
| |
| if (tso_segs == 1) { |
| if (unlikely(!tcp_nagle_test(tp, skb, mss_now, |
| (tcp_skb_is_last(sk, skb) ? |
| nonagle : TCP_NAGLE_PUSH)))) |
| break; |
| } else { |
| if (tcp_tso_should_defer(sk, tp, skb)) |
| break; |
| } |
| |
| limit = mss_now; |
| if (tso_segs > 1) { |
| limit = tcp_window_allows(tp, skb, |
| mss_now, cwnd_quota); |
| |
| if (skb->len < limit) { |
| unsigned int trim = skb->len % mss_now; |
| |
| if (trim) |
| limit = skb->len - trim; |
| } |
| } |
| |
| if (skb->len > limit && |
| unlikely(tso_fragment(sk, skb, limit, mss_now))) |
| break; |
| |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| |
| if (unlikely(tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)))) |
| break; |
| |
| /* Advance the send_head. This one is sent out. |
| * This call will increment packets_out. |
| */ |
| update_send_head(sk, tp, skb); |
| |
| tcp_minshall_update(tp, mss_now, skb); |
| sent_pkts++; |
| } |
| |
| if (likely(sent_pkts)) { |
| tcp_cwnd_validate(sk, tp); |
| return 0; |
| } |
| return !tp->packets_out && sk->sk_send_head; |
| } |
| |
| /* Push out any pending frames which were held back due to |
| * TCP_CORK or attempt at coalescing tiny packets. |
| * The socket must be locked by the caller. |
| */ |
| void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp, |
| unsigned int cur_mss, int nonagle) |
| { |
| struct sk_buff *skb = sk->sk_send_head; |
| |
| if (skb) { |
| if (tcp_write_xmit(sk, cur_mss, nonagle)) |
| tcp_check_probe_timer(sk, tp); |
| } |
| } |
| |
| /* Send _single_ skb sitting at the send head. This function requires |
| * true push pending frames to setup probe timer etc. |
| */ |
| void tcp_push_one(struct sock *sk, unsigned int mss_now) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb = sk->sk_send_head; |
| unsigned int tso_segs, cwnd_quota; |
| |
| BUG_ON(!skb || skb->len < mss_now); |
| |
| tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
| cwnd_quota = tcp_snd_test(sk, skb, mss_now, TCP_NAGLE_PUSH); |
| |
| if (likely(cwnd_quota)) { |
| unsigned int limit; |
| |
| BUG_ON(!tso_segs); |
| |
| limit = mss_now; |
| if (tso_segs > 1) { |
| limit = tcp_window_allows(tp, skb, |
| mss_now, cwnd_quota); |
| |
| if (skb->len < limit) { |
| unsigned int trim = skb->len % mss_now; |
| |
| if (trim) |
| limit = skb->len - trim; |
| } |
| } |
| |
| if (skb->len > limit && |
| unlikely(tso_fragment(sk, skb, limit, mss_now))) |
| return; |
| |
| /* Send it out now. */ |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| |
| if (likely(!tcp_transmit_skb(sk, skb_clone(skb, sk->sk_allocation)))) { |
| update_send_head(sk, tp, skb); |
| tcp_cwnd_validate(sk, tp); |
| return; |
| } |
| } |
| } |
| |
| /* This function returns the amount that we can raise the |
| * usable window based on the following constraints |
| * |
| * 1. The window can never be shrunk once it is offered (RFC 793) |
| * 2. We limit memory per socket |
| * |
| * RFC 1122: |
| * "the suggested [SWS] avoidance algorithm for the receiver is to keep |
| * RECV.NEXT + RCV.WIN fixed until: |
| * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" |
| * |
| * i.e. don't raise the right edge of the window until you can raise |
| * it at least MSS bytes. |
| * |
| * Unfortunately, the recommended algorithm breaks header prediction, |
| * since header prediction assumes th->window stays fixed. |
| * |
| * Strictly speaking, keeping th->window fixed violates the receiver |
| * side SWS prevention criteria. The problem is that under this rule |
| * a stream of single byte packets will cause the right side of the |
| * window to always advance by a single byte. |
| * |
| * Of course, if the sender implements sender side SWS prevention |
| * then this will not be a problem. |
| * |
| * BSD seems to make the following compromise: |
| * |
| * If the free space is less than the 1/4 of the maximum |
| * space available and the free space is less than 1/2 mss, |
| * then set the window to 0. |
| * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] |
| * Otherwise, just prevent the window from shrinking |
| * and from being larger than the largest representable value. |
| * |
| * This prevents incremental opening of the window in the regime |
| * where TCP is limited by the speed of the reader side taking |
| * data out of the TCP receive queue. It does nothing about |
| * those cases where the window is constrained on the sender side |
| * because the pipeline is full. |
| * |
| * BSD also seems to "accidentally" limit itself to windows that are a |
| * multiple of MSS, at least until the free space gets quite small. |
| * This would appear to be a side effect of the mbuf implementation. |
| * Combining these two algorithms results in the observed behavior |
| * of having a fixed window size at almost all times. |
| * |
| * Below we obtain similar behavior by forcing the offered window to |
| * a multiple of the mss when it is feasible to do so. |
| * |
| * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. |
| * Regular options like TIMESTAMP are taken into account. |
| */ |
| u32 __tcp_select_window(struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| /* MSS for the peer's data. Previous verions used mss_clamp |
| * here. I don't know if the value based on our guesses |
| * of peer's MSS is better for the performance. It's more correct |
| * but may be worse for the performance because of rcv_mss |
| * fluctuations. --SAW 1998/11/1 |
| */ |
| int mss = icsk->icsk_ack.rcv_mss; |
| int free_space = tcp_space(sk); |
| int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); |
| int window; |
| |
| if (mss > full_space) |
| mss = full_space; |
| |
| if (free_space < full_space/2) { |
| icsk->icsk_ack.quick = 0; |
| |
| if (tcp_memory_pressure) |
| tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U*tp->advmss); |
| |
| if (free_space < mss) |
| return 0; |
| } |
| |
| if (free_space > tp->rcv_ssthresh) |
| free_space = tp->rcv_ssthresh; |
| |
| /* Don't do rounding if we are using window scaling, since the |
| * scaled window will not line up with the MSS boundary anyway. |
| */ |
| window = tp->rcv_wnd; |
| if (tp->rx_opt.rcv_wscale) { |
| window = free_space; |
| |
| /* Advertise enough space so that it won't get scaled away. |
| * Import case: prevent zero window announcement if |
| * 1<<rcv_wscale > mss. |
| */ |
| if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) |
| window = (((window >> tp->rx_opt.rcv_wscale) + 1) |
| << tp->rx_opt.rcv_wscale); |
| } else { |
| /* Get the largest window that is a nice multiple of mss. |
| * Window clamp already applied above. |
| * If our current window offering is within 1 mss of the |
| * free space we just keep it. This prevents the divide |
| * and multiply from happening most of the time. |
| * We also don't do any window rounding when the free space |
| * is too small. |
| */ |
| if (window <= free_space - mss || window > free_space) |
| window = (free_space/mss)*mss; |
| } |
| |
| return window; |
| } |
| |
| /* Attempt to collapse two adjacent SKB's during retransmission. */ |
| static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int mss_now) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *next_skb = skb->next; |
| |
| /* The first test we must make is that neither of these two |
| * SKB's are still referenced by someone else. |
| */ |
| if (!skb_cloned(skb) && !skb_cloned(next_skb)) { |
| int skb_size = skb->len, next_skb_size = next_skb->len; |
| u16 flags = TCP_SKB_CB(skb)->flags; |
| |
| /* Also punt if next skb has been SACK'd. */ |
| if(TCP_SKB_CB(next_skb)->sacked & TCPCB_SACKED_ACKED) |
| return; |
| |
| /* Next skb is out of window. */ |
| if (after(TCP_SKB_CB(next_skb)->end_seq, tp->snd_una+tp->snd_wnd)) |
| return; |
| |
| /* Punt if not enough space exists in the first SKB for |
| * the data in the second, or the total combined payload |
| * would exceed the MSS. |
| */ |
| if ((next_skb_size > skb_tailroom(skb)) || |
| ((skb_size + next_skb_size) > mss_now)) |
| return; |
| |
| BUG_ON(tcp_skb_pcount(skb) != 1 || |
| tcp_skb_pcount(next_skb) != 1); |
| |
| /* Ok. We will be able to collapse the packet. */ |
| __skb_unlink(next_skb, &sk->sk_write_queue); |
| |
| memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size); |
| |
| if (next_skb->ip_summed == CHECKSUM_HW) |
| skb->ip_summed = CHECKSUM_HW; |
| |
| if (skb->ip_summed != CHECKSUM_HW) |
| skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); |
| |
| /* Update sequence range on original skb. */ |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; |
| |
| /* Merge over control information. */ |
| flags |= TCP_SKB_CB(next_skb)->flags; /* This moves PSH/FIN etc. over */ |
| TCP_SKB_CB(skb)->flags = flags; |
| |
| /* All done, get rid of second SKB and account for it so |
| * packet counting does not break. |
| */ |
| TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked&(TCPCB_EVER_RETRANS|TCPCB_AT_TAIL); |
| if (TCP_SKB_CB(next_skb)->sacked&TCPCB_SACKED_RETRANS) |
| tp->retrans_out -= tcp_skb_pcount(next_skb); |
| if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST) { |
| tp->lost_out -= tcp_skb_pcount(next_skb); |
| tp->left_out -= tcp_skb_pcount(next_skb); |
| } |
| /* Reno case is special. Sigh... */ |
| if (!tp->rx_opt.sack_ok && tp->sacked_out) { |
| tcp_dec_pcount_approx(&tp->sacked_out, next_skb); |
| tp->left_out -= tcp_skb_pcount(next_skb); |
| } |
| |
| /* Not quite right: it can be > snd.fack, but |
| * it is better to underestimate fackets. |
| */ |
| tcp_dec_pcount_approx(&tp->fackets_out, next_skb); |
| tcp_packets_out_dec(tp, next_skb); |
| sk_stream_free_skb(sk, next_skb); |
| } |
| } |
| |
| /* Do a simple retransmit without using the backoff mechanisms in |
| * tcp_timer. This is used for path mtu discovery. |
| * The socket is already locked here. |
| */ |
| void tcp_simple_retransmit(struct sock *sk) |
| { |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| unsigned int mss = tcp_current_mss(sk, 0); |
| int lost = 0; |
| |
| sk_stream_for_retrans_queue(skb, sk) { |
| if (skb->len > mss && |
| !(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) { |
| if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { |
| TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; |
| tp->retrans_out -= tcp_skb_pcount(skb); |
| } |
| if (!(TCP_SKB_CB(skb)->sacked&TCPCB_LOST)) { |
| TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; |
| tp->lost_out += tcp_skb_pcount(skb); |
| lost = 1; |
| } |
| } |
| } |
| |
| if (!lost) |
| return; |
| |
| tcp_sync_left_out(tp); |
| |
| /* Don't muck with the congestion window here. |
| * Reason is that we do not increase amount of _data_ |
| * in network, but units changed and effective |
| * cwnd/ssthresh really reduced now. |
| */ |
| if (icsk->icsk_ca_state != TCP_CA_Loss) { |
| tp->high_seq = tp->snd_nxt; |
| tp->snd_ssthresh = tcp_current_ssthresh(sk); |
| tp->prior_ssthresh = 0; |
| tp->undo_marker = 0; |
| tcp_set_ca_state(sk, TCP_CA_Loss); |
| } |
| tcp_xmit_retransmit_queue(sk); |
| } |
| |
| /* This retransmits one SKB. Policy decisions and retransmit queue |
| * state updates are done by the caller. Returns non-zero if an |
| * error occurred which prevented the send. |
| */ |
| int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| unsigned int cur_mss = tcp_current_mss(sk, 0); |
| int err; |
| |
| /* Do not sent more than we queued. 1/4 is reserved for possible |
| * copying overhead: frgagmentation, tunneling, mangling etc. |
| */ |
| if (atomic_read(&sk->sk_wmem_alloc) > |
| min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) |
| return -EAGAIN; |
| |
| if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { |
| if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) |
| BUG(); |
| |
| if (sk->sk_route_caps & NETIF_F_TSO) { |
| sk->sk_route_caps &= ~NETIF_F_TSO; |
| sock_set_flag(sk, SOCK_NO_LARGESEND); |
| } |
| |
| if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
| return -ENOMEM; |
| } |
| |
| /* If receiver has shrunk his window, and skb is out of |
| * new window, do not retransmit it. The exception is the |
| * case, when window is shrunk to zero. In this case |
| * our retransmit serves as a zero window probe. |
| */ |
| if (!before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd) |
| && TCP_SKB_CB(skb)->seq != tp->snd_una) |
| return -EAGAIN; |
| |
| if (skb->len > cur_mss) { |
| int old_factor = tcp_skb_pcount(skb); |
| int diff; |
| |
| if (tcp_fragment(sk, skb, cur_mss, cur_mss)) |
| return -ENOMEM; /* We'll try again later. */ |
| |
| /* New SKB created, account for it. */ |
| diff = old_factor - tcp_skb_pcount(skb) - |
| tcp_skb_pcount(skb->next); |
| tp->packets_out -= diff; |
| |
| if (diff > 0) { |
| tp->fackets_out -= diff; |
| if ((int)tp->fackets_out < 0) |
| tp->fackets_out = 0; |
| } |
| } |
| |
| /* Collapse two adjacent packets if worthwhile and we can. */ |
| if(!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN) && |
| (skb->len < (cur_mss >> 1)) && |
| (skb->next != sk->sk_send_head) && |
| (skb->next != (struct sk_buff *)&sk->sk_write_queue) && |
| (skb_shinfo(skb)->nr_frags == 0 && skb_shinfo(skb->next)->nr_frags == 0) && |
| (tcp_skb_pcount(skb) == 1 && tcp_skb_pcount(skb->next) == 1) && |
| (sysctl_tcp_retrans_collapse != 0)) |
| tcp_retrans_try_collapse(sk, skb, cur_mss); |
| |
| if(tp->af_specific->rebuild_header(sk)) |
| return -EHOSTUNREACH; /* Routing failure or similar. */ |
| |
| /* Some Solaris stacks overoptimize and ignore the FIN on a |
| * retransmit when old data is attached. So strip it off |
| * since it is cheap to do so and saves bytes on the network. |
| */ |
| if(skb->len > 0 && |
| (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && |
| tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { |
| if (!pskb_trim(skb, 0)) { |
| TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1; |
| skb_shinfo(skb)->tso_segs = 1; |
| skb_shinfo(skb)->tso_size = 0; |
| skb->ip_summed = CHECKSUM_NONE; |
| skb->csum = 0; |
| } |
| } |
| |
| /* Make a copy, if the first transmission SKB clone we made |
| * is still in somebody's hands, else make a clone. |
| */ |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| |
| err = tcp_transmit_skb(sk, (skb_cloned(skb) ? |
| pskb_copy(skb, GFP_ATOMIC): |
| skb_clone(skb, GFP_ATOMIC))); |
| |
| if (err == 0) { |
| /* Update global TCP statistics. */ |
| TCP_INC_STATS(TCP_MIB_RETRANSSEGS); |
| |
| tp->total_retrans++; |
| |
| #if FASTRETRANS_DEBUG > 0 |
| if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { |
| if (net_ratelimit()) |
| printk(KERN_DEBUG "retrans_out leaked.\n"); |
| } |
| #endif |
| TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; |
| tp->retrans_out += tcp_skb_pcount(skb); |
| |
| /* Save stamp of the first retransmit. */ |
| if (!tp->retrans_stamp) |
| tp->retrans_stamp = TCP_SKB_CB(skb)->when; |
| |
| tp->undo_retrans++; |
| |
| /* snd_nxt is stored to detect loss of retransmitted segment, |
| * see tcp_input.c tcp_sacktag_write_queue(). |
| */ |
| TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; |
| } |
| return err; |
| } |
| |
| /* This gets called after a retransmit timeout, and the initially |
| * retransmitted data is acknowledged. It tries to continue |
| * resending the rest of the retransmit queue, until either |
| * we've sent it all or the congestion window limit is reached. |
| * If doing SACK, the first ACK which comes back for a timeout |
| * based retransmit packet might feed us FACK information again. |
| * If so, we use it to avoid unnecessarily retransmissions. |
| */ |
| void tcp_xmit_retransmit_queue(struct sock *sk) |
| { |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| int packet_cnt = tp->lost_out; |
| |
| /* First pass: retransmit lost packets. */ |
| if (packet_cnt) { |
| sk_stream_for_retrans_queue(skb, sk) { |
| __u8 sacked = TCP_SKB_CB(skb)->sacked; |
| |
| /* Assume this retransmit will generate |
| * only one packet for congestion window |
| * calculation purposes. This works because |
| * tcp_retransmit_skb() will chop up the |
| * packet to be MSS sized and all the |
| * packet counting works out. |
| */ |
| if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) |
| return; |
| |
| if (sacked&TCPCB_LOST) { |
| if (!(sacked&(TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) { |
| if (tcp_retransmit_skb(sk, skb)) |
| return; |
| if (icsk->icsk_ca_state != TCP_CA_Loss) |
| NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS); |
| else |
| NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS); |
| |
| if (skb == |
| skb_peek(&sk->sk_write_queue)) |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
| inet_csk(sk)->icsk_rto, |
| TCP_RTO_MAX); |
| } |
| |
| packet_cnt -= tcp_skb_pcount(skb); |
| if (packet_cnt <= 0) |
| break; |
| } |
| } |
| } |
| |
| /* OK, demanded retransmission is finished. */ |
| |
| /* Forward retransmissions are possible only during Recovery. */ |
| if (icsk->icsk_ca_state != TCP_CA_Recovery) |
| return; |
| |
| /* No forward retransmissions in Reno are possible. */ |
| if (!tp->rx_opt.sack_ok) |
| return; |
| |
| /* Yeah, we have to make difficult choice between forward transmission |
| * and retransmission... Both ways have their merits... |
| * |
| * For now we do not retransmit anything, while we have some new |
| * segments to send. |
| */ |
| |
| if (tcp_may_send_now(sk, tp)) |
| return; |
| |
| packet_cnt = 0; |
| |
| sk_stream_for_retrans_queue(skb, sk) { |
| /* Similar to the retransmit loop above we |
| * can pretend that the retransmitted SKB |
| * we send out here will be composed of one |
| * real MSS sized packet because tcp_retransmit_skb() |
| * will fragment it if necessary. |
| */ |
| if (++packet_cnt > tp->fackets_out) |
| break; |
| |
| if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) |
| break; |
| |
| if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) |
| continue; |
| |
| /* Ok, retransmit it. */ |
| if (tcp_retransmit_skb(sk, skb)) |
| break; |
| |
| if (skb == skb_peek(&sk->sk_write_queue)) |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
| inet_csk(sk)->icsk_rto, |
| TCP_RTO_MAX); |
| |
| NET_INC_STATS_BH(LINUX_MIB_TCPFORWARDRETRANS); |
| } |
| } |
| |
| |
| /* Send a fin. The caller locks the socket for us. This cannot be |
| * allowed to fail queueing a FIN frame under any circumstances. |
| */ |
| void tcp_send_fin(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb = skb_peek_tail(&sk->sk_write_queue); |
| int mss_now; |
| |
| /* Optimization, tack on the FIN if we have a queue of |
| * unsent frames. But be careful about outgoing SACKS |
| * and IP options. |
| */ |
| mss_now = tcp_current_mss(sk, 1); |
| |
| if (sk->sk_send_head != NULL) { |
| TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; |
| TCP_SKB_CB(skb)->end_seq++; |
| tp->write_seq++; |
| } else { |
| /* Socket is locked, keep trying until memory is available. */ |
| for (;;) { |
| skb = alloc_skb(MAX_TCP_HEADER, GFP_KERNEL); |
| if (skb) |
| break; |
| yield(); |
| } |
| |
| /* Reserve space for headers and prepare control bits. */ |
| skb_reserve(skb, MAX_TCP_HEADER); |
| skb->csum = 0; |
| TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); |
| TCP_SKB_CB(skb)->sacked = 0; |
| skb_shinfo(skb)->tso_segs = 1; |
| skb_shinfo(skb)->tso_size = 0; |
| |
| /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
| TCP_SKB_CB(skb)->seq = tp->write_seq; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; |
| tcp_queue_skb(sk, skb); |
| } |
| __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_OFF); |
| } |
| |
| /* We get here when a process closes a file descriptor (either due to |
| * an explicit close() or as a byproduct of exit()'ing) and there |
| * was unread data in the receive queue. This behavior is recommended |
| * by draft-ietf-tcpimpl-prob-03.txt section 3.10. -DaveM |
| */ |
| void tcp_send_active_reset(struct sock *sk, unsigned int __nocast priority) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| |
| /* NOTE: No TCP options attached and we never retransmit this. */ |
| skb = alloc_skb(MAX_TCP_HEADER, priority); |
| if (!skb) { |
| NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); |
| return; |
| } |
| |
| /* Reserve space for headers and prepare control bits. */ |
| skb_reserve(skb, MAX_TCP_HEADER); |
| skb->csum = 0; |
| TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST); |
| TCP_SKB_CB(skb)->sacked = 0; |
| skb_shinfo(skb)->tso_segs = 1; |
| skb_shinfo(skb)->tso_size = 0; |
| |
| /* Send it off. */ |
| TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk, tp); |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| if (tcp_transmit_skb(sk, skb)) |
| NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); |
| } |
| |
| /* WARNING: This routine must only be called when we have already sent |
| * a SYN packet that crossed the incoming SYN that caused this routine |
| * to get called. If this assumption fails then the initial rcv_wnd |
| * and rcv_wscale values will not be correct. |
| */ |
| int tcp_send_synack(struct sock *sk) |
| { |
| struct sk_buff* skb; |
| |
| skb = skb_peek(&sk->sk_write_queue); |
| if (skb == NULL || !(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_SYN)) { |
| printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); |
| return -EFAULT; |
| } |
| if (!(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_ACK)) { |
| if (skb_cloned(skb)) { |
| struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); |
| if (nskb == NULL) |
| return -ENOMEM; |
| __skb_unlink(skb, &sk->sk_write_queue); |
| skb_header_release(nskb); |
| __skb_queue_head(&sk->sk_write_queue, nskb); |
| sk_stream_free_skb(sk, skb); |
| sk_charge_skb(sk, nskb); |
| skb = nskb; |
| } |
| |
| TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ACK; |
| TCP_ECN_send_synack(tcp_sk(sk), skb); |
| } |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| return tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)); |
| } |
| |
| /* |
| * Prepare a SYN-ACK. |
| */ |
| struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, |
| struct request_sock *req) |
| { |
| struct inet_request_sock *ireq = inet_rsk(req); |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct tcphdr *th; |
| int tcp_header_size; |
| struct sk_buff *skb; |
| |
| skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); |
| if (skb == NULL) |
| return NULL; |
| |
| /* Reserve space for headers. */ |
| skb_reserve(skb, MAX_TCP_HEADER); |
| |
| skb->dst = dst_clone(dst); |
| |
| tcp_header_size = (sizeof(struct tcphdr) + TCPOLEN_MSS + |
| (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) + |
| (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) + |
| /* SACK_PERM is in the place of NOP NOP of TS */ |
| ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0)); |
| skb->h.th = th = (struct tcphdr *) skb_push(skb, tcp_header_size); |
| |
| memset(th, 0, sizeof(struct tcphdr)); |
| th->syn = 1; |
| th->ack = 1; |
| if (dst->dev->features&NETIF_F_TSO) |
| ireq->ecn_ok = 0; |
| TCP_ECN_make_synack(req, th); |
| th->source = inet_sk(sk)->sport; |
| th->dest = ireq->rmt_port; |
| TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; |
| TCP_SKB_CB(skb)->sacked = 0; |
| skb_shinfo(skb)->tso_segs = 1; |
| skb_shinfo(skb)->tso_size = 0; |
| th->seq = htonl(TCP_SKB_CB(skb)->seq); |
| th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); |
| if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ |
| __u8 rcv_wscale; |
| /* Set this up on the first call only */ |
| req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); |
| /* tcp_full_space because it is guaranteed to be the first packet */ |
| tcp_select_initial_window(tcp_full_space(sk), |
| dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
| &req->rcv_wnd, |
| &req->window_clamp, |
| ireq->wscale_ok, |
| &rcv_wscale); |
| ireq->rcv_wscale = rcv_wscale; |
| } |
| |
| /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ |
| th->window = htons(req->rcv_wnd); |
| |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| tcp_syn_build_options((__u32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok, |
| ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale, |
| TCP_SKB_CB(skb)->when, |
| req->ts_recent); |
| |
| skb->csum = 0; |
| th->doff = (tcp_header_size >> 2); |
| TCP_INC_STATS(TCP_MIB_OUTSEGS); |
| return skb; |
| } |
| |
| /* |
| * Do all connect socket setups that can be done AF independent. |
| */ |
| static inline void tcp_connect_init(struct sock *sk) |
| { |
| struct dst_entry *dst = __sk_dst_get(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| __u8 rcv_wscale; |
| |
| /* We'll fix this up when we get a response from the other end. |
| * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. |
| */ |
| tp->tcp_header_len = sizeof(struct tcphdr) + |
| (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); |
| |
| /* If user gave his TCP_MAXSEG, record it to clamp */ |
| if (tp->rx_opt.user_mss) |
| tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; |
| tp->max_window = 0; |
| tcp_sync_mss(sk, dst_mtu(dst)); |
| |
| if (!tp->window_clamp) |
| tp->window_clamp = dst_metric(dst, RTAX_WINDOW); |
| tp->advmss = dst_metric(dst, RTAX_ADVMSS); |
| tcp_initialize_rcv_mss(sk); |
| |
| tcp_select_initial_window(tcp_full_space(sk), |
| tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), |
| &tp->rcv_wnd, |
| &tp->window_clamp, |
| sysctl_tcp_window_scaling, |
| &rcv_wscale); |
| |
| tp->rx_opt.rcv_wscale = rcv_wscale; |
| tp->rcv_ssthresh = tp->rcv_wnd; |
| |
| sk->sk_err = 0; |
| sock_reset_flag(sk, SOCK_DONE); |
| tp->snd_wnd = 0; |
| tcp_init_wl(tp, tp->write_seq, 0); |
| tp->snd_una = tp->write_seq; |
| tp->snd_sml = tp->write_seq; |
| tp->rcv_nxt = 0; |
| tp->rcv_wup = 0; |
| tp->copied_seq = 0; |
| |
| inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
| inet_csk(sk)->icsk_retransmits = 0; |
| tcp_clear_retrans(tp); |
| } |
| |
| /* |
| * Build a SYN and send it off. |
| */ |
| int tcp_connect(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *buff; |
| |
| tcp_connect_init(sk); |
| |
| buff = alloc_skb(MAX_TCP_HEADER + 15, sk->sk_allocation); |
| if (unlikely(buff == NULL)) |
| return -ENOBUFS; |
| |
| /* Reserve space for headers. */ |
| skb_reserve(buff, MAX_TCP_HEADER); |
| |
| TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN; |
| TCP_ECN_send_syn(sk, tp, buff); |
| TCP_SKB_CB(buff)->sacked = 0; |
| skb_shinfo(buff)->tso_segs = 1; |
| skb_shinfo(buff)->tso_size = 0; |
| buff->csum = 0; |
| TCP_SKB_CB(buff)->seq = tp->write_seq++; |
| TCP_SKB_CB(buff)->end_seq = tp->write_seq; |
| tp->snd_nxt = tp->write_seq; |
| tp->pushed_seq = tp->write_seq; |
| |
| /* Send it off. */ |
| TCP_SKB_CB(buff)->when = tcp_time_stamp; |
| tp->retrans_stamp = TCP_SKB_CB(buff)->when; |
| skb_header_release(buff); |
| __skb_queue_tail(&sk->sk_write_queue, buff); |
| sk_charge_skb(sk, buff); |
| tp->packets_out += tcp_skb_pcount(buff); |
| tcp_transmit_skb(sk, skb_clone(buff, GFP_KERNEL)); |
| TCP_INC_STATS(TCP_MIB_ACTIVEOPENS); |
| |
| /* Timer for repeating the SYN until an answer. */ |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
| inet_csk(sk)->icsk_rto, TCP_RTO_MAX); |
| return 0; |
| } |
| |
| /* Send out a delayed ack, the caller does the policy checking |
| * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() |
| * for details. |
| */ |
| void tcp_send_delayed_ack(struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| int ato = icsk->icsk_ack.ato; |
| unsigned long timeout; |
| |
| if (ato > TCP_DELACK_MIN) { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| int max_ato = HZ/2; |
| |
| if (icsk->icsk_ack.pingpong || (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) |
| max_ato = TCP_DELACK_MAX; |
| |
| /* Slow path, intersegment interval is "high". */ |
| |
| /* If some rtt estimate is known, use it to bound delayed ack. |
| * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
| * directly. |
| */ |
| if (tp->srtt) { |
| int rtt = max(tp->srtt>>3, TCP_DELACK_MIN); |
| |
| if (rtt < max_ato) |
| max_ato = rtt; |
| } |
| |
| ato = min(ato, max_ato); |
| } |
| |
| /* Stay within the limit we were given */ |
| timeout = jiffies + ato; |
| |
| /* Use new timeout only if there wasn't a older one earlier. */ |
| if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
| /* If delack timer was blocked or is about to expire, |
| * send ACK now. |
| */ |
| if (icsk->icsk_ack.blocked || |
| time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { |
| tcp_send_ack(sk); |
| return; |
| } |
| |
| if (!time_before(timeout, icsk->icsk_ack.timeout)) |
| timeout = icsk->icsk_ack.timeout; |
| } |
| icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
| icsk->icsk_ack.timeout = timeout; |
| sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); |
| } |
| |
| /* This routine sends an ack and also updates the window. */ |
| void tcp_send_ack(struct sock *sk) |
| { |
| /* If we have been reset, we may not send again. */ |
| if (sk->sk_state != TCP_CLOSE) { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *buff; |
| |
| /* We are not putting this on the write queue, so |
| * tcp_transmit_skb() will set the ownership to this |
| * sock. |
| */ |
| buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); |
| if (buff == NULL) { |
| inet_csk_schedule_ack(sk); |
| inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, |
| TCP_DELACK_MAX, TCP_RTO_MAX); |
| return; |
| } |
| |
| /* Reserve space for headers and prepare control bits. */ |
| skb_reserve(buff, MAX_TCP_HEADER); |
| buff->csum = 0; |
| TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK; |
| TCP_SKB_CB(buff)->sacked = 0; |
| skb_shinfo(buff)->tso_segs = 1; |
| skb_shinfo(buff)->tso_size = 0; |
| |
| /* Send it off, this clears delayed acks for us. */ |
| TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk, tp); |
| TCP_SKB_CB(buff)->when = tcp_time_stamp; |
| tcp_transmit_skb(sk, buff); |
| } |
| } |
| |
| /* This routine sends a packet with an out of date sequence |
| * number. It assumes the other end will try to ack it. |
| * |
| * Question: what should we make while urgent mode? |
| * 4.4BSD forces sending single byte of data. We cannot send |
| * out of window data, because we have SND.NXT==SND.MAX... |
| * |
| * Current solution: to send TWO zero-length segments in urgent mode: |
| * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is |
| * out-of-date with SND.UNA-1 to probe window. |
| */ |
| static int tcp_xmit_probe_skb(struct sock *sk, int urgent) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| |
| /* We don't queue it, tcp_transmit_skb() sets ownership. */ |
| skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); |
| if (skb == NULL) |
| return -1; |
| |
| /* Reserve space for headers and set control bits. */ |
| skb_reserve(skb, MAX_TCP_HEADER); |
| skb->csum = 0; |
| TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK; |
| TCP_SKB_CB(skb)->sacked = urgent; |
| skb_shinfo(skb)->tso_segs = 1; |
| skb_shinfo(skb)->tso_size = 0; |
| |
| /* Use a previous sequence. This should cause the other |
| * end to send an ack. Don't queue or clone SKB, just |
| * send it. |
| */ |
| TCP_SKB_CB(skb)->seq = urgent ? tp->snd_una : tp->snd_una - 1; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| return tcp_transmit_skb(sk, skb); |
| } |
| |
| int tcp_write_wakeup(struct sock *sk) |
| { |
| if (sk->sk_state != TCP_CLOSE) { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| |
| if ((skb = sk->sk_send_head) != NULL && |
| before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd)) { |
| int err; |
| unsigned int mss = tcp_current_mss(sk, 0); |
| unsigned int seg_size = tp->snd_una+tp->snd_wnd-TCP_SKB_CB(skb)->seq; |
| |
| if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) |
| tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; |
| |
| /* We are probing the opening of a window |
| * but the window size is != 0 |
| * must have been a result SWS avoidance ( sender ) |
| */ |
| if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || |
| skb->len > mss) { |
| seg_size = min(seg_size, mss); |
| TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; |
| if (tcp_fragment(sk, skb, seg_size, mss)) |
| return -1; |
| /* SWS override triggered forced fragmentation. |
| * Disable TSO, the connection is too sick. */ |
| if (sk->sk_route_caps & NETIF_F_TSO) { |
| sock_set_flag(sk, SOCK_NO_LARGESEND); |
| sk->sk_route_caps &= ~NETIF_F_TSO; |
| } |
| } else if (!tcp_skb_pcount(skb)) |
| tcp_set_skb_tso_segs(sk, skb, mss); |
| |
| TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; |
| TCP_SKB_CB(skb)->when = tcp_time_stamp; |
| err = tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC)); |
| if (!err) { |
| update_send_head(sk, tp, skb); |
| } |
| return err; |
| } else { |
| if (tp->urg_mode && |
| between(tp->snd_up, tp->snd_una+1, tp->snd_una+0xFFFF)) |
| tcp_xmit_probe_skb(sk, TCPCB_URG); |
| return tcp_xmit_probe_skb(sk, 0); |
| } |
| } |
| return -1; |
| } |
| |
| /* A window probe timeout has occurred. If window is not closed send |
| * a partial packet else a zero probe. |
| */ |
| void tcp_send_probe0(struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| int err; |
| |
| err = tcp_write_wakeup(sk); |
| |
| if (tp->packets_out || !sk->sk_send_head) { |
| /* Cancel probe timer, if it is not required. */ |
| icsk->icsk_probes_out = 0; |
| icsk->icsk_backoff = 0; |
| return; |
| } |
| |
| if (err <= 0) { |
| if (icsk->icsk_backoff < sysctl_tcp_retries2) |
| icsk->icsk_backoff++; |
| icsk->icsk_probes_out++; |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
| min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), |
| TCP_RTO_MAX); |
| } else { |
| /* If packet was not sent due to local congestion, |
| * do not backoff and do not remember icsk_probes_out. |
| * Let local senders to fight for local resources. |
| * |
| * Use accumulated backoff yet. |
| */ |
| if (!icsk->icsk_probes_out) |
| icsk->icsk_probes_out = 1; |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
| min(icsk->icsk_rto << icsk->icsk_backoff, |
| TCP_RESOURCE_PROBE_INTERVAL), |
| TCP_RTO_MAX); |
| } |
| } |
| |
| EXPORT_SYMBOL(tcp_connect); |
| EXPORT_SYMBOL(tcp_make_synack); |
| EXPORT_SYMBOL(tcp_simple_retransmit); |
| EXPORT_SYMBOL(tcp_sync_mss); |