![Feng King](/assets/img/avatar_default.png)
TCP_NODELAY is weaker than TCP_CORK, when TCP_CORK was set, small segments will always pass Nagle test regardless of TCP_NODELAY option. Signed-off-by: Feng King <kinwin2008@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2866 lines
82 KiB
C
2866 lines
82 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Implementation of the Transmission Control Protocol(TCP).
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*
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* Authors: Ross Biro
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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* Mark Evans, <evansmp@uhura.aston.ac.uk>
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* Corey Minyard <wf-rch!minyard@relay.EU.net>
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* Florian La Roche, <flla@stud.uni-sb.de>
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* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
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* Linus Torvalds, <torvalds@cs.helsinki.fi>
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* Alan Cox, <gw4pts@gw4pts.ampr.org>
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* Matthew Dillon, <dillon@apollo.west.oic.com>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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* Jorge Cwik, <jorge@laser.satlink.net>
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*/
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/*
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* Changes: Pedro Roque : Retransmit queue handled by TCP.
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* : Fragmentation on mtu decrease
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* : Segment collapse on retransmit
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* : AF independence
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*
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* Linus Torvalds : send_delayed_ack
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* David S. Miller : Charge memory using the right skb
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* during syn/ack processing.
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* David S. Miller : Output engine completely rewritten.
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* Andrea Arcangeli: SYNACK carry ts_recent in tsecr.
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* Cacophonix Gaul : draft-minshall-nagle-01
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* J Hadi Salim : ECN support
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*
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*/
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#include <net/tcp.h>
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#include <linux/compiler.h>
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#include <linux/gfp.h>
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#include <linux/module.h>
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/* People can turn this off for buggy TCP's found in printers etc. */
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int sysctl_tcp_retrans_collapse __read_mostly = 1;
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/* People can turn this on to work with those rare, broken TCPs that
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* interpret the window field as a signed quantity.
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*/
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int sysctl_tcp_workaround_signed_windows __read_mostly = 0;
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/* This limits the percentage of the congestion window which we
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* will allow a single TSO frame to consume. Building TSO frames
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* which are too large can cause TCP streams to be bursty.
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*/
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int sysctl_tcp_tso_win_divisor __read_mostly = 3;
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int sysctl_tcp_mtu_probing __read_mostly = 0;
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int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS;
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/* By default, RFC2861 behavior. */
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int sysctl_tcp_slow_start_after_idle __read_mostly = 1;
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int sysctl_tcp_cookie_size __read_mostly = 0; /* TCP_COOKIE_MAX */
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EXPORT_SYMBOL_GPL(sysctl_tcp_cookie_size);
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/* Account for new data that has been sent to the network. */
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static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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unsigned int prior_packets = tp->packets_out;
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tcp_advance_send_head(sk, skb);
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tp->snd_nxt = TCP_SKB_CB(skb)->end_seq;
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/* Don't override Nagle indefinitely with F-RTO */
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if (tp->frto_counter == 2)
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tp->frto_counter = 3;
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tp->packets_out += tcp_skb_pcount(skb);
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if (!prior_packets)
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
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inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
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}
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/* SND.NXT, if window was not shrunk.
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* If window has been shrunk, what should we make? It is not clear at all.
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* Using SND.UNA we will fail to open window, SND.NXT is out of window. :-(
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* Anything in between SND.UNA...SND.UNA+SND.WND also can be already
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* invalid. OK, let's make this for now:
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*/
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static inline __u32 tcp_acceptable_seq(const struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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if (!before(tcp_wnd_end(tp), tp->snd_nxt))
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return tp->snd_nxt;
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else
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return tcp_wnd_end(tp);
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}
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/* Calculate mss to advertise in SYN segment.
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* RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that:
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*
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* 1. It is independent of path mtu.
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* 2. Ideally, it is maximal possible segment size i.e. 65535-40.
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* 3. For IPv4 it is reasonable to calculate it from maximal MTU of
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* attached devices, because some buggy hosts are confused by
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* large MSS.
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* 4. We do not make 3, we advertise MSS, calculated from first
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* hop device mtu, but allow to raise it to ip_rt_min_advmss.
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* This may be overridden via information stored in routing table.
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* 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible,
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* probably even Jumbo".
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*/
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static __u16 tcp_advertise_mss(struct sock *sk)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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const struct dst_entry *dst = __sk_dst_get(sk);
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int mss = tp->advmss;
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if (dst) {
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unsigned int metric = dst_metric_advmss(dst);
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if (metric < mss) {
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mss = metric;
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tp->advmss = mss;
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}
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}
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return (__u16)mss;
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}
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/* RFC2861. Reset CWND after idle period longer RTO to "restart window".
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* This is the first part of cwnd validation mechanism. */
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static void tcp_cwnd_restart(struct sock *sk, const struct dst_entry *dst)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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s32 delta = tcp_time_stamp - tp->lsndtime;
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u32 restart_cwnd = tcp_init_cwnd(tp, dst);
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u32 cwnd = tp->snd_cwnd;
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tcp_ca_event(sk, CA_EVENT_CWND_RESTART);
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tp->snd_ssthresh = tcp_current_ssthresh(sk);
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restart_cwnd = min(restart_cwnd, cwnd);
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while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd)
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cwnd >>= 1;
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tp->snd_cwnd = max(cwnd, restart_cwnd);
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tp->snd_cwnd_stamp = tcp_time_stamp;
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tp->snd_cwnd_used = 0;
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}
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/* Congestion state accounting after a packet has been sent. */
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static void tcp_event_data_sent(struct tcp_sock *tp,
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struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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const u32 now = tcp_time_stamp;
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if (sysctl_tcp_slow_start_after_idle &&
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(!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto))
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tcp_cwnd_restart(sk, __sk_dst_get(sk));
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tp->lsndtime = now;
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/* If it is a reply for ato after last received
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* packet, enter pingpong mode.
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*/
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if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato)
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icsk->icsk_ack.pingpong = 1;
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}
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/* Account for an ACK we sent. */
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static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
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{
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tcp_dec_quickack_mode(sk, pkts);
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
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}
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/* Determine a window scaling and initial window to offer.
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* Based on the assumption that the given amount of space
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* will be offered. Store the results in the tp structure.
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* NOTE: for smooth operation initial space offering should
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* be a multiple of mss if possible. We assume here that mss >= 1.
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* This MUST be enforced by all callers.
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*/
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void tcp_select_initial_window(int __space, __u32 mss,
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__u32 *rcv_wnd, __u32 *window_clamp,
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int wscale_ok, __u8 *rcv_wscale,
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__u32 init_rcv_wnd)
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{
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unsigned int space = (__space < 0 ? 0 : __space);
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/* If no clamp set the clamp to the max possible scaled window */
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if (*window_clamp == 0)
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(*window_clamp) = (65535 << 14);
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space = min(*window_clamp, space);
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/* Quantize space offering to a multiple of mss if possible. */
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if (space > mss)
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space = (space / mss) * mss;
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/* NOTE: offering an initial window larger than 32767
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* will break some buggy TCP stacks. If the admin tells us
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* it is likely we could be speaking with such a buggy stack
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* we will truncate our initial window offering to 32K-1
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* unless the remote has sent us a window scaling option,
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* which we interpret as a sign the remote TCP is not
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* misinterpreting the window field as a signed quantity.
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*/
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if (sysctl_tcp_workaround_signed_windows)
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(*rcv_wnd) = min(space, MAX_TCP_WINDOW);
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else
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(*rcv_wnd) = space;
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(*rcv_wscale) = 0;
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if (wscale_ok) {
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/* Set window scaling on max possible window
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* See RFC1323 for an explanation of the limit to 14
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*/
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space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max);
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space = min_t(u32, space, *window_clamp);
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while (space > 65535 && (*rcv_wscale) < 14) {
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space >>= 1;
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(*rcv_wscale)++;
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}
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}
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/* Set initial window to a value enough for senders starting with
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* initial congestion window of TCP_DEFAULT_INIT_RCVWND. Place
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* a limit on the initial window when mss is larger than 1460.
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*/
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if (mss > (1 << *rcv_wscale)) {
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int init_cwnd = TCP_DEFAULT_INIT_RCVWND;
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if (mss > 1460)
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init_cwnd =
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max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2);
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/* when initializing use the value from init_rcv_wnd
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* rather than the default from above
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*/
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if (init_rcv_wnd)
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*rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss);
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else
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*rcv_wnd = min(*rcv_wnd, init_cwnd * mss);
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}
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/* Set the clamp no higher than max representable value */
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(*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp);
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}
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EXPORT_SYMBOL(tcp_select_initial_window);
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/* Chose a new window to advertise, update state in tcp_sock for the
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* socket, and return result with RFC1323 scaling applied. The return
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* value can be stuffed directly into th->window for an outgoing
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* frame.
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*/
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static u16 tcp_select_window(struct sock *sk)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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u32 cur_win = tcp_receive_window(tp);
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u32 new_win = __tcp_select_window(sk);
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/* Never shrink the offered window */
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if (new_win < cur_win) {
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/* Danger Will Robinson!
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* Don't update rcv_wup/rcv_wnd here or else
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* we will not be able to advertise a zero
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* window in time. --DaveM
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*
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* Relax Will Robinson.
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*/
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new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale);
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}
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tp->rcv_wnd = new_win;
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tp->rcv_wup = tp->rcv_nxt;
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/* Make sure we do not exceed the maximum possible
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* scaled window.
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*/
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if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows)
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new_win = min(new_win, MAX_TCP_WINDOW);
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else
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new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));
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/* RFC1323 scaling applied */
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new_win >>= tp->rx_opt.rcv_wscale;
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/* If we advertise zero window, disable fast path. */
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if (new_win == 0)
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tp->pred_flags = 0;
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return new_win;
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}
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/* Packet ECN state for a SYN-ACK */
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static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb)
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{
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR;
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if (!(tp->ecn_flags & TCP_ECN_OK))
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE;
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}
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/* Packet ECN state for a SYN. */
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static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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tp->ecn_flags = 0;
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if (sysctl_tcp_ecn == 1) {
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TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR;
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tp->ecn_flags = TCP_ECN_OK;
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}
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}
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static __inline__ void
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TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th)
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{
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if (inet_rsk(req)->ecn_ok)
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th->ece = 1;
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}
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/* Set up ECN state for a packet on a ESTABLISHED socket that is about to
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* be sent.
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*/
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static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb,
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int tcp_header_len)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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if (tp->ecn_flags & TCP_ECN_OK) {
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/* Not-retransmitted data segment: set ECT and inject CWR. */
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if (skb->len != tcp_header_len &&
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!before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) {
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INET_ECN_xmit(sk);
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if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) {
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tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR;
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tcp_hdr(skb)->cwr = 1;
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
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}
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} else {
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/* ACK or retransmitted segment: clear ECT|CE */
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INET_ECN_dontxmit(sk);
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}
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if (tp->ecn_flags & TCP_ECN_DEMAND_CWR)
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tcp_hdr(skb)->ece = 1;
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}
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}
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/* Constructs common control bits of non-data skb. If SYN/FIN is present,
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* auto increment end seqno.
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*/
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static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
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{
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skb->ip_summed = CHECKSUM_PARTIAL;
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skb->csum = 0;
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TCP_SKB_CB(skb)->tcp_flags = flags;
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TCP_SKB_CB(skb)->sacked = 0;
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skb_shinfo(skb)->gso_segs = 1;
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skb_shinfo(skb)->gso_size = 0;
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skb_shinfo(skb)->gso_type = 0;
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TCP_SKB_CB(skb)->seq = seq;
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if (flags & (TCPHDR_SYN | TCPHDR_FIN))
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seq++;
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TCP_SKB_CB(skb)->end_seq = seq;
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}
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static inline int tcp_urg_mode(const struct tcp_sock *tp)
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{
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return tp->snd_una != tp->snd_up;
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}
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#define OPTION_SACK_ADVERTISE (1 << 0)
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#define OPTION_TS (1 << 1)
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#define OPTION_MD5 (1 << 2)
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#define OPTION_WSCALE (1 << 3)
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#define OPTION_COOKIE_EXTENSION (1 << 4)
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struct tcp_out_options {
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u8 options; /* bit field of OPTION_* */
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u8 ws; /* window scale, 0 to disable */
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u8 num_sack_blocks; /* number of SACK blocks to include */
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u8 hash_size; /* bytes in hash_location */
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u16 mss; /* 0 to disable */
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__u32 tsval, tsecr; /* need to include OPTION_TS */
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__u8 *hash_location; /* temporary pointer, overloaded */
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};
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/* The sysctl int routines are generic, so check consistency here.
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*/
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static u8 tcp_cookie_size_check(u8 desired)
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{
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int cookie_size;
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if (desired > 0)
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/* previously specified */
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return desired;
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cookie_size = ACCESS_ONCE(sysctl_tcp_cookie_size);
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if (cookie_size <= 0)
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/* no default specified */
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return 0;
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if (cookie_size <= TCP_COOKIE_MIN)
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/* value too small, specify minimum */
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return TCP_COOKIE_MIN;
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if (cookie_size >= TCP_COOKIE_MAX)
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/* value too large, specify maximum */
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return TCP_COOKIE_MAX;
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if (cookie_size & 1)
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/* 8-bit multiple, illegal, fix it */
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cookie_size++;
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return (u8)cookie_size;
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}
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/* Write previously computed TCP options to the packet.
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*
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* Beware: Something in the Internet is very sensitive to the ordering of
|
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* TCP options, we learned this through the hard way, so be careful here.
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* Luckily we can at least blame others for their non-compliance but from
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* inter-operatibility perspective it seems that we're somewhat stuck with
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* the ordering which we have been using if we want to keep working with
|
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* those broken things (not that it currently hurts anybody as there isn't
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* particular reason why the ordering would need to be changed).
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*
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* At least SACK_PERM as the first option is known to lead to a disaster
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* (but it may well be that other scenarios fail similarly).
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*/
|
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static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
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struct tcp_out_options *opts)
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{
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u8 options = opts->options; /* mungable copy */
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|
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/* Having both authentication and cookies for security is redundant,
|
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* and there's certainly not enough room. Instead, the cookie-less
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* extension variant is proposed.
|
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*
|
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* Consider the pessimal case with authentication. The options
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* could look like:
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* COOKIE|MD5(20) + MSS(4) + SACK|TS(12) + WSCALE(4) == 40
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*/
|
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if (unlikely(OPTION_MD5 & options)) {
|
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if (unlikely(OPTION_COOKIE_EXTENSION & options)) {
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*ptr++ = htonl((TCPOPT_COOKIE << 24) |
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(TCPOLEN_COOKIE_BASE << 16) |
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(TCPOPT_MD5SIG << 8) |
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TCPOLEN_MD5SIG);
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} else {
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*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_MD5SIG << 8) |
|
|
TCPOLEN_MD5SIG);
|
|
}
|
|
options &= ~OPTION_COOKIE_EXTENSION;
|
|
/* overload cookie hash location */
|
|
opts->hash_location = (__u8 *)ptr;
|
|
ptr += 4;
|
|
}
|
|
|
|
if (unlikely(opts->mss)) {
|
|
*ptr++ = htonl((TCPOPT_MSS << 24) |
|
|
(TCPOLEN_MSS << 16) |
|
|
opts->mss);
|
|
}
|
|
|
|
if (likely(OPTION_TS & options)) {
|
|
if (unlikely(OPTION_SACK_ADVERTISE & options)) {
|
|
*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
|
|
(TCPOLEN_SACK_PERM << 16) |
|
|
(TCPOPT_TIMESTAMP << 8) |
|
|
TCPOLEN_TIMESTAMP);
|
|
options &= ~OPTION_SACK_ADVERTISE;
|
|
} else {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_TIMESTAMP << 8) |
|
|
TCPOLEN_TIMESTAMP);
|
|
}
|
|
*ptr++ = htonl(opts->tsval);
|
|
*ptr++ = htonl(opts->tsecr);
|
|
}
|
|
|
|
/* Specification requires after timestamp, so do it now.
|
|
*
|
|
* Consider the pessimal case without authentication. The options
|
|
* could look like:
|
|
* MSS(4) + SACK|TS(12) + COOKIE(20) + WSCALE(4) == 40
|
|
*/
|
|
if (unlikely(OPTION_COOKIE_EXTENSION & options)) {
|
|
__u8 *cookie_copy = opts->hash_location;
|
|
u8 cookie_size = opts->hash_size;
|
|
|
|
/* 8-bit multiple handled in tcp_cookie_size_check() above,
|
|
* and elsewhere.
|
|
*/
|
|
if (0x2 & cookie_size) {
|
|
__u8 *p = (__u8 *)ptr;
|
|
|
|
/* 16-bit multiple */
|
|
*p++ = TCPOPT_COOKIE;
|
|
*p++ = TCPOLEN_COOKIE_BASE + cookie_size;
|
|
*p++ = *cookie_copy++;
|
|
*p++ = *cookie_copy++;
|
|
ptr++;
|
|
cookie_size -= 2;
|
|
} else {
|
|
/* 32-bit multiple */
|
|
*ptr++ = htonl(((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_COOKIE << 8) |
|
|
TCPOLEN_COOKIE_BASE) +
|
|
cookie_size);
|
|
}
|
|
|
|
if (cookie_size > 0) {
|
|
memcpy(ptr, cookie_copy, cookie_size);
|
|
ptr += (cookie_size / 4);
|
|
}
|
|
}
|
|
|
|
if (unlikely(OPTION_SACK_ADVERTISE & options)) {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_SACK_PERM << 8) |
|
|
TCPOLEN_SACK_PERM);
|
|
}
|
|
|
|
if (unlikely(OPTION_WSCALE & options)) {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_WINDOW << 16) |
|
|
(TCPOLEN_WINDOW << 8) |
|
|
opts->ws);
|
|
}
|
|
|
|
if (unlikely(opts->num_sack_blocks)) {
|
|
struct tcp_sack_block *sp = tp->rx_opt.dsack ?
|
|
tp->duplicate_sack : tp->selective_acks;
|
|
int this_sack;
|
|
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_SACK << 8) |
|
|
(TCPOLEN_SACK_BASE + (opts->num_sack_blocks *
|
|
TCPOLEN_SACK_PERBLOCK)));
|
|
|
|
for (this_sack = 0; this_sack < opts->num_sack_blocks;
|
|
++this_sack) {
|
|
*ptr++ = htonl(sp[this_sack].start_seq);
|
|
*ptr++ = htonl(sp[this_sack].end_seq);
|
|
}
|
|
|
|
tp->rx_opt.dsack = 0;
|
|
}
|
|
}
|
|
|
|
/* Compute TCP options for SYN packets. This is not the final
|
|
* network wire format yet.
|
|
*/
|
|
static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
|
|
struct tcp_out_options *opts,
|
|
struct tcp_md5sig_key **md5)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct tcp_cookie_values *cvp = tp->cookie_values;
|
|
unsigned remaining = MAX_TCP_OPTION_SPACE;
|
|
u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ?
|
|
tcp_cookie_size_check(cvp->cookie_desired) :
|
|
0;
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
*md5 = tp->af_specific->md5_lookup(sk, sk);
|
|
if (*md5) {
|
|
opts->options |= OPTION_MD5;
|
|
remaining -= TCPOLEN_MD5SIG_ALIGNED;
|
|
}
|
|
#else
|
|
*md5 = NULL;
|
|
#endif
|
|
|
|
/* We always get an MSS option. The option bytes which will be seen in
|
|
* normal data packets should timestamps be used, must be in the MSS
|
|
* advertised. But we subtract them from tp->mss_cache so that
|
|
* calculations in tcp_sendmsg are simpler etc. So account for this
|
|
* fact here if necessary. If we don't do this correctly, as a
|
|
* receiver we won't recognize data packets as being full sized when we
|
|
* should, and thus we won't abide by the delayed ACK rules correctly.
|
|
* SACKs don't matter, we never delay an ACK when we have any of those
|
|
* going out. */
|
|
opts->mss = tcp_advertise_mss(sk);
|
|
remaining -= TCPOLEN_MSS_ALIGNED;
|
|
|
|
if (likely(sysctl_tcp_timestamps && *md5 == NULL)) {
|
|
opts->options |= OPTION_TS;
|
|
opts->tsval = TCP_SKB_CB(skb)->when;
|
|
opts->tsecr = tp->rx_opt.ts_recent;
|
|
remaining -= TCPOLEN_TSTAMP_ALIGNED;
|
|
}
|
|
if (likely(sysctl_tcp_window_scaling)) {
|
|
opts->ws = tp->rx_opt.rcv_wscale;
|
|
opts->options |= OPTION_WSCALE;
|
|
remaining -= TCPOLEN_WSCALE_ALIGNED;
|
|
}
|
|
if (likely(sysctl_tcp_sack)) {
|
|
opts->options |= OPTION_SACK_ADVERTISE;
|
|
if (unlikely(!(OPTION_TS & opts->options)))
|
|
remaining -= TCPOLEN_SACKPERM_ALIGNED;
|
|
}
|
|
|
|
/* Note that timestamps are required by the specification.
|
|
*
|
|
* Odd numbers of bytes are prohibited by the specification, ensuring
|
|
* that the cookie is 16-bit aligned, and the resulting cookie pair is
|
|
* 32-bit aligned.
|
|
*/
|
|
if (*md5 == NULL &&
|
|
(OPTION_TS & opts->options) &&
|
|
cookie_size > 0) {
|
|
int need = TCPOLEN_COOKIE_BASE + cookie_size;
|
|
|
|
if (0x2 & need) {
|
|
/* 32-bit multiple */
|
|
need += 2; /* NOPs */
|
|
|
|
if (need > remaining) {
|
|
/* try shrinking cookie to fit */
|
|
cookie_size -= 2;
|
|
need -= 4;
|
|
}
|
|
}
|
|
while (need > remaining && TCP_COOKIE_MIN <= cookie_size) {
|
|
cookie_size -= 4;
|
|
need -= 4;
|
|
}
|
|
if (TCP_COOKIE_MIN <= cookie_size) {
|
|
opts->options |= OPTION_COOKIE_EXTENSION;
|
|
opts->hash_location = (__u8 *)&cvp->cookie_pair[0];
|
|
opts->hash_size = cookie_size;
|
|
|
|
/* Remember for future incarnations. */
|
|
cvp->cookie_desired = cookie_size;
|
|
|
|
if (cvp->cookie_desired != cvp->cookie_pair_size) {
|
|
/* Currently use random bytes as a nonce,
|
|
* assuming these are completely unpredictable
|
|
* by hostile users of the same system.
|
|
*/
|
|
get_random_bytes(&cvp->cookie_pair[0],
|
|
cookie_size);
|
|
cvp->cookie_pair_size = cookie_size;
|
|
}
|
|
|
|
remaining -= need;
|
|
}
|
|
}
|
|
return MAX_TCP_OPTION_SPACE - remaining;
|
|
}
|
|
|
|
/* Set up TCP options for SYN-ACKs. */
|
|
static unsigned tcp_synack_options(struct sock *sk,
|
|
struct request_sock *req,
|
|
unsigned mss, struct sk_buff *skb,
|
|
struct tcp_out_options *opts,
|
|
struct tcp_md5sig_key **md5,
|
|
struct tcp_extend_values *xvp)
|
|
{
|
|
struct inet_request_sock *ireq = inet_rsk(req);
|
|
unsigned remaining = MAX_TCP_OPTION_SPACE;
|
|
u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ?
|
|
xvp->cookie_plus :
|
|
0;
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
*md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
|
|
if (*md5) {
|
|
opts->options |= OPTION_MD5;
|
|
remaining -= TCPOLEN_MD5SIG_ALIGNED;
|
|
|
|
/* We can't fit any SACK blocks in a packet with MD5 + TS
|
|
* options. There was discussion about disabling SACK
|
|
* rather than TS in order to fit in better with old,
|
|
* buggy kernels, but that was deemed to be unnecessary.
|
|
*/
|
|
ireq->tstamp_ok &= !ireq->sack_ok;
|
|
}
|
|
#else
|
|
*md5 = NULL;
|
|
#endif
|
|
|
|
/* We always send an MSS option. */
|
|
opts->mss = mss;
|
|
remaining -= TCPOLEN_MSS_ALIGNED;
|
|
|
|
if (likely(ireq->wscale_ok)) {
|
|
opts->ws = ireq->rcv_wscale;
|
|
opts->options |= OPTION_WSCALE;
|
|
remaining -= TCPOLEN_WSCALE_ALIGNED;
|
|
}
|
|
if (likely(ireq->tstamp_ok)) {
|
|
opts->options |= OPTION_TS;
|
|
opts->tsval = TCP_SKB_CB(skb)->when;
|
|
opts->tsecr = req->ts_recent;
|
|
remaining -= TCPOLEN_TSTAMP_ALIGNED;
|
|
}
|
|
if (likely(ireq->sack_ok)) {
|
|
opts->options |= OPTION_SACK_ADVERTISE;
|
|
if (unlikely(!ireq->tstamp_ok))
|
|
remaining -= TCPOLEN_SACKPERM_ALIGNED;
|
|
}
|
|
|
|
/* Similar rationale to tcp_syn_options() applies here, too.
|
|
* If the <SYN> options fit, the same options should fit now!
|
|
*/
|
|
if (*md5 == NULL &&
|
|
ireq->tstamp_ok &&
|
|
cookie_plus > TCPOLEN_COOKIE_BASE) {
|
|
int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */
|
|
|
|
if (0x2 & need) {
|
|
/* 32-bit multiple */
|
|
need += 2; /* NOPs */
|
|
}
|
|
if (need <= remaining) {
|
|
opts->options |= OPTION_COOKIE_EXTENSION;
|
|
opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE;
|
|
remaining -= need;
|
|
} else {
|
|
/* There's no error return, so flag it. */
|
|
xvp->cookie_out_never = 1; /* true */
|
|
opts->hash_size = 0;
|
|
}
|
|
}
|
|
return MAX_TCP_OPTION_SPACE - remaining;
|
|
}
|
|
|
|
/* Compute TCP options for ESTABLISHED sockets. This is not the
|
|
* final wire format yet.
|
|
*/
|
|
static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb,
|
|
struct tcp_out_options *opts,
|
|
struct tcp_md5sig_key **md5)
|
|
{
|
|
struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL;
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
unsigned size = 0;
|
|
unsigned int eff_sacks;
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
*md5 = tp->af_specific->md5_lookup(sk, sk);
|
|
if (unlikely(*md5)) {
|
|
opts->options |= OPTION_MD5;
|
|
size += TCPOLEN_MD5SIG_ALIGNED;
|
|
}
|
|
#else
|
|
*md5 = NULL;
|
|
#endif
|
|
|
|
if (likely(tp->rx_opt.tstamp_ok)) {
|
|
opts->options |= OPTION_TS;
|
|
opts->tsval = tcb ? tcb->when : 0;
|
|
opts->tsecr = tp->rx_opt.ts_recent;
|
|
size += TCPOLEN_TSTAMP_ALIGNED;
|
|
}
|
|
|
|
eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
|
|
if (unlikely(eff_sacks)) {
|
|
const unsigned remaining = MAX_TCP_OPTION_SPACE - size;
|
|
opts->num_sack_blocks =
|
|
min_t(unsigned, eff_sacks,
|
|
(remaining - TCPOLEN_SACK_BASE_ALIGNED) /
|
|
TCPOLEN_SACK_PERBLOCK);
|
|
size += TCPOLEN_SACK_BASE_ALIGNED +
|
|
opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
|
|
}
|
|
|
|
return size;
|
|
}
|
|
|
|
/* 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, int clone_it,
|
|
gfp_t gfp_mask)
|
|
{
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct inet_sock *inet;
|
|
struct tcp_sock *tp;
|
|
struct tcp_skb_cb *tcb;
|
|
struct tcp_out_options opts;
|
|
unsigned tcp_options_size, tcp_header_size;
|
|
struct tcp_md5sig_key *md5;
|
|
struct tcphdr *th;
|
|
int err;
|
|
|
|
BUG_ON(!skb || !tcp_skb_pcount(skb));
|
|
|
|
/* If congestion control is doing timestamping, we must
|
|
* take such a timestamp before we potentially clone/copy.
|
|
*/
|
|
if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP)
|
|
__net_timestamp(skb);
|
|
|
|
if (likely(clone_it)) {
|
|
if (unlikely(skb_cloned(skb)))
|
|
skb = pskb_copy(skb, gfp_mask);
|
|
else
|
|
skb = skb_clone(skb, gfp_mask);
|
|
if (unlikely(!skb))
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
inet = inet_sk(sk);
|
|
tp = tcp_sk(sk);
|
|
tcb = TCP_SKB_CB(skb);
|
|
memset(&opts, 0, sizeof(opts));
|
|
|
|
if (unlikely(tcb->tcp_flags & TCPHDR_SYN))
|
|
tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5);
|
|
else
|
|
tcp_options_size = tcp_established_options(sk, skb, &opts,
|
|
&md5);
|
|
tcp_header_size = tcp_options_size + sizeof(struct tcphdr);
|
|
|
|
if (tcp_packets_in_flight(tp) == 0) {
|
|
tcp_ca_event(sk, CA_EVENT_TX_START);
|
|
skb->ooo_okay = 1;
|
|
} else
|
|
skb->ooo_okay = 0;
|
|
|
|
skb_push(skb, tcp_header_size);
|
|
skb_reset_transport_header(skb);
|
|
skb_set_owner_w(skb, sk);
|
|
|
|
/* Build TCP header and checksum it. */
|
|
th = tcp_hdr(skb);
|
|
th->source = inet->inet_sport;
|
|
th->dest = inet->inet_dport;
|
|
th->seq = htonl(tcb->seq);
|
|
th->ack_seq = htonl(tp->rcv_nxt);
|
|
*(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) |
|
|
tcb->tcp_flags);
|
|
|
|
if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) {
|
|
/* RFC1323: The window in SYN & SYN/ACK segments
|
|
* is never scaled.
|
|
*/
|
|
th->window = htons(min(tp->rcv_wnd, 65535U));
|
|
} else {
|
|
th->window = htons(tcp_select_window(sk));
|
|
}
|
|
th->check = 0;
|
|
th->urg_ptr = 0;
|
|
|
|
/* The urg_mode check is necessary during a below snd_una win probe */
|
|
if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) {
|
|
if (before(tp->snd_up, tcb->seq + 0x10000)) {
|
|
th->urg_ptr = htons(tp->snd_up - tcb->seq);
|
|
th->urg = 1;
|
|
} else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) {
|
|
th->urg_ptr = htons(0xFFFF);
|
|
th->urg = 1;
|
|
}
|
|
}
|
|
|
|
tcp_options_write((__be32 *)(th + 1), tp, &opts);
|
|
if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0))
|
|
TCP_ECN_send(sk, skb, tcp_header_size);
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
/* Calculate the MD5 hash, as we have all we need now */
|
|
if (md5) {
|
|
sk_nocaps_add(sk, NETIF_F_GSO_MASK);
|
|
tp->af_specific->calc_md5_hash(opts.hash_location,
|
|
md5, sk, NULL, skb);
|
|
}
|
|
#endif
|
|
|
|
icsk->icsk_af_ops->send_check(sk, skb);
|
|
|
|
if (likely(tcb->tcp_flags & TCPHDR_ACK))
|
|
tcp_event_ack_sent(sk, tcp_skb_pcount(skb));
|
|
|
|
if (skb->len != tcp_header_size)
|
|
tcp_event_data_sent(tp, sk);
|
|
|
|
if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq)
|
|
TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS,
|
|
tcp_skb_pcount(skb));
|
|
|
|
err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl);
|
|
if (likely(err <= 0))
|
|
return err;
|
|
|
|
tcp_enter_cwr(sk, 1);
|
|
|
|
return net_xmit_eval(err);
|
|
}
|
|
|
|
/* This routine just queues the buffer for sending.
|
|
*
|
|
* 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);
|
|
tcp_add_write_queue_tail(sk, skb);
|
|
sk->sk_wmem_queued += skb->truesize;
|
|
sk_mem_charge(sk, skb->truesize);
|
|
}
|
|
|
|
/* Initialize TSO segments for a packet. */
|
|
static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
|
|
unsigned int mss_now)
|
|
{
|
|
if (skb->len <= mss_now || !sk_can_gso(sk) ||
|
|
skb->ip_summed == CHECKSUM_NONE) {
|
|
/* Avoid the costly divide in the normal
|
|
* non-TSO case.
|
|
*/
|
|
skb_shinfo(skb)->gso_segs = 1;
|
|
skb_shinfo(skb)->gso_size = 0;
|
|
skb_shinfo(skb)->gso_type = 0;
|
|
} else {
|
|
skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now);
|
|
skb_shinfo(skb)->gso_size = mss_now;
|
|
skb_shinfo(skb)->gso_type = sk->sk_gso_type;
|
|
}
|
|
}
|
|
|
|
/* When a modification to fackets out becomes necessary, we need to check
|
|
* skb is counted to fackets_out or not.
|
|
*/
|
|
static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb,
|
|
int decr)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
if (!tp->sacked_out || tcp_is_reno(tp))
|
|
return;
|
|
|
|
if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq))
|
|
tp->fackets_out -= decr;
|
|
}
|
|
|
|
/* Pcount in the middle of the write queue got changed, we need to do various
|
|
* tweaks to fix counters
|
|
*/
|
|
static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
tp->packets_out -= decr;
|
|
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
|
|
tp->sacked_out -= decr;
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
|
|
tp->retrans_out -= decr;
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST)
|
|
tp->lost_out -= decr;
|
|
|
|
/* Reno case is special. Sigh... */
|
|
if (tcp_is_reno(tp) && decr > 0)
|
|
tp->sacked_out -= min_t(u32, tp->sacked_out, decr);
|
|
|
|
tcp_adjust_fackets_out(sk, skb, decr);
|
|
|
|
if (tp->lost_skb_hint &&
|
|
before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) &&
|
|
(tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)))
|
|
tp->lost_cnt_hint -= decr;
|
|
|
|
tcp_verify_left_out(tp);
|
|
}
|
|
|
|
/* 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.
|
|
*/
|
|
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, old_factor;
|
|
int nlen;
|
|
u8 flags;
|
|
|
|
if (WARN_ON(len > skb->len))
|
|
return -EINVAL;
|
|
|
|
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->sk_wmem_queued += buff->truesize;
|
|
sk_mem_charge(sk, buff->truesize);
|
|
nlen = skb->len - len - nsize;
|
|
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)->tcp_flags;
|
|
TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
|
|
TCP_SKB_CB(buff)->tcp_flags = flags;
|
|
TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked;
|
|
|
|
if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) {
|
|
/* 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_PARTIAL;
|
|
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;
|
|
|
|
old_factor = 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 this packet has been sent out already, we must
|
|
* adjust the various packet counters.
|
|
*/
|
|
if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) {
|
|
int diff = old_factor - tcp_skb_pcount(skb) -
|
|
tcp_skb_pcount(buff);
|
|
|
|
if (diff)
|
|
tcp_adjust_pcount(sk, skb, diff);
|
|
}
|
|
|
|
/* Link BUFF into the send queue. */
|
|
skb_header_release(buff);
|
|
tcp_insert_write_queue_after(skb, buff, sk);
|
|
|
|
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 void __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++) {
|
|
int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
|
|
|
|
if (size <= eat) {
|
|
skb_frag_unref(skb, i);
|
|
eat -= size;
|
|
} else {
|
|
skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
|
|
if (eat) {
|
|
skb_shinfo(skb)->frags[k].page_offset += eat;
|
|
skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
|
|
eat = 0;
|
|
}
|
|
k++;
|
|
}
|
|
}
|
|
skb_shinfo(skb)->nr_frags = k;
|
|
|
|
skb_reset_tail_pointer(skb);
|
|
skb->data_len -= len;
|
|
skb->len = skb->data_len;
|
|
}
|
|
|
|
/* Remove acked data from a packet in the transmit queue. */
|
|
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 == headlen, we avoid __skb_pull to preserve alignment. */
|
|
if (unlikely(len < skb_headlen(skb)))
|
|
__skb_pull(skb, len);
|
|
else
|
|
__pskb_trim_head(skb, len - skb_headlen(skb));
|
|
|
|
TCP_SKB_CB(skb)->seq += len;
|
|
skb->ip_summed = CHECKSUM_PARTIAL;
|
|
|
|
skb->truesize -= len;
|
|
sk->sk_wmem_queued -= len;
|
|
sk_mem_uncharge(sk, 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));
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Calculate MSS. Not accounting for SACKs here. */
|
|
int tcp_mtu_to_mss(const struct sock *sk, int pmtu)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int mss_now;
|
|
|
|
/* Calculate base mss without TCP options:
|
|
It is MMS_S - sizeof(tcphdr) of rfc1122
|
|
*/
|
|
mss_now = pmtu - icsk->icsk_af_ops->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 -= icsk->icsk_ext_hdr_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);
|
|
|
|
return mss_now;
|
|
}
|
|
|
|
/* Inverse of above */
|
|
int tcp_mss_to_mtu(const struct sock *sk, int mss)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int mtu;
|
|
|
|
mtu = mss +
|
|
tp->tcp_header_len +
|
|
icsk->icsk_ext_hdr_len +
|
|
icsk->icsk_af_ops->net_header_len;
|
|
|
|
return mtu;
|
|
}
|
|
|
|
/* MTU probing init per socket */
|
|
void tcp_mtup_init(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
|
|
icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1;
|
|
icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) +
|
|
icsk->icsk_af_ops->net_header_len;
|
|
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss);
|
|
icsk->icsk_mtup.probe_size = 0;
|
|
}
|
|
EXPORT_SYMBOL(tcp_mtup_init);
|
|
|
|
/* 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 minimum of user_mss and mss received with SYN.
|
|
It also does not include TCP options.
|
|
|
|
inet_csk(sk)->icsk_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. inet_csk(sk)->icsk_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);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int mss_now;
|
|
|
|
if (icsk->icsk_mtup.search_high > pmtu)
|
|
icsk->icsk_mtup.search_high = pmtu;
|
|
|
|
mss_now = tcp_mtu_to_mss(sk, pmtu);
|
|
mss_now = tcp_bound_to_half_wnd(tp, mss_now);
|
|
|
|
/* And store cached results */
|
|
icsk->icsk_pmtu_cookie = pmtu;
|
|
if (icsk->icsk_mtup.enabled)
|
|
mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low));
|
|
tp->mss_cache = mss_now;
|
|
|
|
return mss_now;
|
|
}
|
|
EXPORT_SYMBOL(tcp_sync_mss);
|
|
|
|
/* Compute the current effective MSS, taking SACKs and IP options,
|
|
* and even PMTU discovery events into account.
|
|
*/
|
|
unsigned int tcp_current_mss(struct sock *sk)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct dst_entry *dst = __sk_dst_get(sk);
|
|
u32 mss_now;
|
|
unsigned header_len;
|
|
struct tcp_out_options opts;
|
|
struct tcp_md5sig_key *md5;
|
|
|
|
mss_now = tp->mss_cache;
|
|
|
|
if (dst) {
|
|
u32 mtu = dst_mtu(dst);
|
|
if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
|
|
mss_now = tcp_sync_mss(sk, mtu);
|
|
}
|
|
|
|
header_len = tcp_established_options(sk, NULL, &opts, &md5) +
|
|
sizeof(struct tcphdr);
|
|
/* The mss_cache is sized based on tp->tcp_header_len, which assumes
|
|
* some common options. If this is an odd packet (because we have SACK
|
|
* blocks etc) then our calculated header_len will be different, and
|
|
* we have to adjust mss_now correspondingly */
|
|
if (header_len != tp->tcp_header_len) {
|
|
int delta = (int) header_len - tp->tcp_header_len;
|
|
mss_now -= delta;
|
|
}
|
|
|
|
return mss_now;
|
|
}
|
|
|
|
/* Congestion window validation. (RFC2861) */
|
|
static void tcp_cwnd_validate(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
if (tp->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 (sysctl_tcp_slow_start_after_idle &&
|
|
(s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto)
|
|
tcp_cwnd_application_limited(sk);
|
|
}
|
|
}
|
|
|
|
/* Returns the portion of skb which can be sent right away without
|
|
* introducing MSS oddities to segment boundaries. In rare cases where
|
|
* mss_now != mss_cache, we will request caller to create a small skb
|
|
* per input skb which could be mostly avoided here (if desired).
|
|
*
|
|
* We explicitly want to create a request for splitting write queue tail
|
|
* to a small skb for Nagle purposes while avoiding unnecessary modulos,
|
|
* thus all the complexity (cwnd_len is always MSS multiple which we
|
|
* return whenever allowed by the other factors). Basically we need the
|
|
* modulo only when the receiver window alone is the limiting factor or
|
|
* when we would be allowed to send the split-due-to-Nagle skb fully.
|
|
*/
|
|
static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb,
|
|
unsigned int mss_now, unsigned int cwnd)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
u32 needed, window, cwnd_len;
|
|
|
|
window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
|
|
cwnd_len = mss_now * cwnd;
|
|
|
|
if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk)))
|
|
return cwnd_len;
|
|
|
|
needed = min(skb->len, window);
|
|
|
|
if (cwnd_len <= needed)
|
|
return cwnd_len;
|
|
|
|
return needed - needed % mss_now;
|
|
}
|
|
|
|
/* 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(const struct tcp_sock *tp,
|
|
const 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)->tcp_flags & TCPHDR_FIN) &&
|
|
tcp_skb_pcount(skb) == 1)
|
|
return 1;
|
|
|
|
in_flight = tcp_packets_in_flight(tp);
|
|
cwnd = tp->snd_cwnd;
|
|
if (in_flight < cwnd)
|
|
return (cwnd - in_flight);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Initialize TSO state of a skb.
|
|
* This must be invoked the first time we consider transmitting
|
|
* SKB onto the wire.
|
|
*/
|
|
static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
|
|
unsigned int mss_now)
|
|
{
|
|
int tso_segs = tcp_skb_pcount(skb);
|
|
|
|
if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) {
|
|
tcp_set_skb_tso_segs(sk, skb, mss_now);
|
|
tso_segs = tcp_skb_pcount(skb);
|
|
}
|
|
return tso_segs;
|
|
}
|
|
|
|
/* Minshall's variant of the Nagle send check. */
|
|
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_CORK is not set, and TCP_NODELAY is 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(const struct tcp_sock *tp, const 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).
|
|
* Nagle can be ignored during F-RTO too (see RFC4138).
|
|
*/
|
|
if (tcp_urg_mode(tp) || (tp->frto_counter == 2) ||
|
|
(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_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(const struct tcp_sock *tp, const 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, tcp_wnd_end(tp));
|
|
}
|
|
|
|
/* This checks if the data bearing packet SKB (usually tcp_send_head(sk))
|
|
* 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(const struct sock *sk, struct sk_buff *skb,
|
|
unsigned int cur_mss, int nonagle)
|
|
{
|
|
const 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;
|
|
}
|
|
|
|
/* Test if sending is allowed right now. */
|
|
int tcp_may_send_now(struct sock *sk)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb = tcp_send_head(sk);
|
|
|
|
return skb &&
|
|
tcp_snd_test(sk, skb, tcp_current_mss(sk),
|
|
(tcp_skb_is_last(sk, skb) ?
|
|
tp->nonagle : TCP_NAGLE_PUSH));
|
|
}
|
|
|
|
/* 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, gfp_t gfp)
|
|
{
|
|
struct sk_buff *buff;
|
|
int nlen = skb->len - len;
|
|
u8 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_skb(sk, 0, gfp);
|
|
if (unlikely(buff == NULL))
|
|
return -ENOMEM;
|
|
|
|
sk->sk_wmem_queued += buff->truesize;
|
|
sk_mem_charge(sk, buff->truesize);
|
|
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)->tcp_flags;
|
|
TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
|
|
TCP_SKB_CB(buff)->tcp_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_PARTIAL;
|
|
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);
|
|
tcp_insert_write_queue_after(skb, buff, sk);
|
|
|
|
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 sk_buff *skb)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
u32 send_win, cong_win, limit, in_flight;
|
|
int win_divisor;
|
|
|
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
|
|
goto send_now;
|
|
|
|
if (icsk->icsk_ca_state != TCP_CA_Open)
|
|
goto send_now;
|
|
|
|
/* Defer for less than two clock ticks. */
|
|
if (tp->tso_deferred &&
|
|
(((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1)
|
|
goto send_now;
|
|
|
|
in_flight = tcp_packets_in_flight(tp);
|
|
|
|
BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight));
|
|
|
|
send_win = tcp_wnd_end(tp) - 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 a full-sized TSO skb can be sent, do it. */
|
|
if (limit >= sk->sk_gso_max_size)
|
|
goto send_now;
|
|
|
|
/* Middle in queue won't get any more data, full sendable already? */
|
|
if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
|
|
goto send_now;
|
|
|
|
win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor);
|
|
if (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 /= win_divisor;
|
|
if (limit >= chunk)
|
|
goto send_now;
|
|
} 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)
|
|
goto send_now;
|
|
}
|
|
|
|
/* Ok, it looks like it is advisable to defer. */
|
|
tp->tso_deferred = 1 | (jiffies << 1);
|
|
|
|
return 1;
|
|
|
|
send_now:
|
|
tp->tso_deferred = 0;
|
|
return 0;
|
|
}
|
|
|
|
/* Create a new MTU probe if we are ready.
|
|
* MTU probe is regularly attempting to increase the path MTU by
|
|
* deliberately sending larger packets. This discovers routing
|
|
* changes resulting in larger path MTUs.
|
|
*
|
|
* Returns 0 if we should wait to probe (no cwnd available),
|
|
* 1 if a probe was sent,
|
|
* -1 otherwise
|
|
*/
|
|
static int tcp_mtu_probe(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct sk_buff *skb, *nskb, *next;
|
|
int len;
|
|
int probe_size;
|
|
int size_needed;
|
|
int copy;
|
|
int mss_now;
|
|
|
|
/* Not currently probing/verifying,
|
|
* not in recovery,
|
|
* have enough cwnd, and
|
|
* not SACKing (the variable headers throw things off) */
|
|
if (!icsk->icsk_mtup.enabled ||
|
|
icsk->icsk_mtup.probe_size ||
|
|
inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
|
|
tp->snd_cwnd < 11 ||
|
|
tp->rx_opt.num_sacks || tp->rx_opt.dsack)
|
|
return -1;
|
|
|
|
/* Very simple search strategy: just double the MSS. */
|
|
mss_now = tcp_current_mss(sk);
|
|
probe_size = 2 * tp->mss_cache;
|
|
size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache;
|
|
if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) {
|
|
/* TODO: set timer for probe_converge_event */
|
|
return -1;
|
|
}
|
|
|
|
/* Have enough data in the send queue to probe? */
|
|
if (tp->write_seq - tp->snd_nxt < size_needed)
|
|
return -1;
|
|
|
|
if (tp->snd_wnd < size_needed)
|
|
return -1;
|
|
if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp)))
|
|
return 0;
|
|
|
|
/* Do we need to wait to drain cwnd? With none in flight, don't stall */
|
|
if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) {
|
|
if (!tcp_packets_in_flight(tp))
|
|
return -1;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/* We're allowed to probe. Build it now. */
|
|
if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL)
|
|
return -1;
|
|
sk->sk_wmem_queued += nskb->truesize;
|
|
sk_mem_charge(sk, nskb->truesize);
|
|
|
|
skb = tcp_send_head(sk);
|
|
|
|
TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq;
|
|
TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size;
|
|
TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK;
|
|
TCP_SKB_CB(nskb)->sacked = 0;
|
|
nskb->csum = 0;
|
|
nskb->ip_summed = skb->ip_summed;
|
|
|
|
tcp_insert_write_queue_before(nskb, skb, sk);
|
|
|
|
len = 0;
|
|
tcp_for_write_queue_from_safe(skb, next, sk) {
|
|
copy = min_t(int, skb->len, probe_size - len);
|
|
if (nskb->ip_summed)
|
|
skb_copy_bits(skb, 0, skb_put(nskb, copy), copy);
|
|
else
|
|
nskb->csum = skb_copy_and_csum_bits(skb, 0,
|
|
skb_put(nskb, copy),
|
|
copy, nskb->csum);
|
|
|
|
if (skb->len <= copy) {
|
|
/* We've eaten all the data from this skb.
|
|
* Throw it away. */
|
|
TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags;
|
|
tcp_unlink_write_queue(skb, sk);
|
|
sk_wmem_free_skb(sk, skb);
|
|
} else {
|
|
TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags &
|
|
~(TCPHDR_FIN|TCPHDR_PSH);
|
|
if (!skb_shinfo(skb)->nr_frags) {
|
|
skb_pull(skb, copy);
|
|
if (skb->ip_summed != CHECKSUM_PARTIAL)
|
|
skb->csum = csum_partial(skb->data,
|
|
skb->len, 0);
|
|
} else {
|
|
__pskb_trim_head(skb, copy);
|
|
tcp_set_skb_tso_segs(sk, skb, mss_now);
|
|
}
|
|
TCP_SKB_CB(skb)->seq += copy;
|
|
}
|
|
|
|
len += copy;
|
|
|
|
if (len >= probe_size)
|
|
break;
|
|
}
|
|
tcp_init_tso_segs(sk, nskb, nskb->len);
|
|
|
|
/* We're ready to send. If this fails, the probe will
|
|
* be resegmented into mss-sized pieces by tcp_write_xmit(). */
|
|
TCP_SKB_CB(nskb)->when = tcp_time_stamp;
|
|
if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) {
|
|
/* Decrement cwnd here because we are sending
|
|
* effectively two packets. */
|
|
tp->snd_cwnd--;
|
|
tcp_event_new_data_sent(sk, nskb);
|
|
|
|
icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len);
|
|
tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq;
|
|
tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq;
|
|
|
|
return 1;
|
|
}
|
|
|
|
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.
|
|
*
|
|
* LARGESEND note: !tcp_urg_mode is overkill, only frames between
|
|
* snd_up-64k-mss .. snd_up cannot be large. However, taking into
|
|
* account rare use of URG, this is not a big flaw.
|
|
*
|
|
* 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,
|
|
int push_one, gfp_t gfp)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb;
|
|
unsigned int tso_segs, sent_pkts;
|
|
int cwnd_quota;
|
|
int result;
|
|
|
|
sent_pkts = 0;
|
|
|
|
if (!push_one) {
|
|
/* Do MTU probing. */
|
|
result = tcp_mtu_probe(sk);
|
|
if (!result) {
|
|
return 0;
|
|
} else if (result > 0) {
|
|
sent_pkts = 1;
|
|
}
|
|
}
|
|
|
|
while ((skb = tcp_send_head(sk))) {
|
|
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 (!push_one && tcp_tso_should_defer(sk, skb))
|
|
break;
|
|
}
|
|
|
|
limit = mss_now;
|
|
if (tso_segs > 1 && !tcp_urg_mode(tp))
|
|
limit = tcp_mss_split_point(sk, skb, mss_now,
|
|
cwnd_quota);
|
|
|
|
if (skb->len > limit &&
|
|
unlikely(tso_fragment(sk, skb, limit, mss_now, gfp)))
|
|
break;
|
|
|
|
TCP_SKB_CB(skb)->when = tcp_time_stamp;
|
|
|
|
if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp)))
|
|
break;
|
|
|
|
/* Advance the send_head. This one is sent out.
|
|
* This call will increment packets_out.
|
|
*/
|
|
tcp_event_new_data_sent(sk, skb);
|
|
|
|
tcp_minshall_update(tp, mss_now, skb);
|
|
sent_pkts += tcp_skb_pcount(skb);
|
|
|
|
if (push_one)
|
|
break;
|
|
}
|
|
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery)
|
|
tp->prr_out += sent_pkts;
|
|
|
|
if (likely(sent_pkts)) {
|
|
tcp_cwnd_validate(sk);
|
|
return 0;
|
|
}
|
|
return !tp->packets_out && tcp_send_head(sk);
|
|
}
|
|
|
|
/* 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, unsigned int cur_mss,
|
|
int nonagle)
|
|
{
|
|
/* 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;
|
|
|
|
if (tcp_write_xmit(sk, cur_mss, nonagle, 0, GFP_ATOMIC))
|
|
tcp_check_probe_timer(sk);
|
|
}
|
|
|
|
/* 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 sk_buff *skb = tcp_send_head(sk);
|
|
|
|
BUG_ON(!skb || skb->len < mss_now);
|
|
|
|
tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation);
|
|
}
|
|
|
|
/* 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 versions 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 >> 1)) {
|
|
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;
|
|
else if (mss == full_space &&
|
|
free_space > window + (full_space >> 1))
|
|
window = free_space;
|
|
}
|
|
|
|
return window;
|
|
}
|
|
|
|
/* Collapses two adjacent SKB's during retransmission. */
|
|
static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *next_skb = tcp_write_queue_next(sk, skb);
|
|
int skb_size, next_skb_size;
|
|
|
|
skb_size = skb->len;
|
|
next_skb_size = next_skb->len;
|
|
|
|
BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1);
|
|
|
|
tcp_highest_sack_combine(sk, next_skb, skb);
|
|
|
|
tcp_unlink_write_queue(next_skb, sk);
|
|
|
|
skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size),
|
|
next_skb_size);
|
|
|
|
if (next_skb->ip_summed == CHECKSUM_PARTIAL)
|
|
skb->ip_summed = CHECKSUM_PARTIAL;
|
|
|
|
if (skb->ip_summed != CHECKSUM_PARTIAL)
|
|
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. This moves PSH/FIN etc. over */
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_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;
|
|
|
|
/* changed transmit queue under us so clear hints */
|
|
tcp_clear_retrans_hints_partial(tp);
|
|
if (next_skb == tp->retransmit_skb_hint)
|
|
tp->retransmit_skb_hint = skb;
|
|
|
|
tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb));
|
|
|
|
sk_wmem_free_skb(sk, next_skb);
|
|
}
|
|
|
|
/* Check if coalescing SKBs is legal. */
|
|
static int tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb)
|
|
{
|
|
if (tcp_skb_pcount(skb) > 1)
|
|
return 0;
|
|
/* TODO: SACK collapsing could be used to remove this condition */
|
|
if (skb_shinfo(skb)->nr_frags != 0)
|
|
return 0;
|
|
if (skb_cloned(skb))
|
|
return 0;
|
|
if (skb == tcp_send_head(sk))
|
|
return 0;
|
|
/* Some heurestics for collapsing over SACK'd could be invented */
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Collapse packets in the retransmit queue to make to create
|
|
* less packets on the wire. This is only done on retransmission.
|
|
*/
|
|
static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to,
|
|
int space)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb = to, *tmp;
|
|
int first = 1;
|
|
|
|
if (!sysctl_tcp_retrans_collapse)
|
|
return;
|
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
|
|
return;
|
|
|
|
tcp_for_write_queue_from_safe(skb, tmp, sk) {
|
|
if (!tcp_can_collapse(sk, skb))
|
|
break;
|
|
|
|
space -= skb->len;
|
|
|
|
if (first) {
|
|
first = 0;
|
|
continue;
|
|
}
|
|
|
|
if (space < 0)
|
|
break;
|
|
/* Punt if not enough space exists in the first SKB for
|
|
* the data in the second
|
|
*/
|
|
if (skb->len > skb_tailroom(to))
|
|
break;
|
|
|
|
if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp)))
|
|
break;
|
|
|
|
tcp_collapse_retrans(sk, to);
|
|
}
|
|
}
|
|
|
|
/* 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);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
unsigned int cur_mss;
|
|
int err;
|
|
|
|
/* Inconslusive MTU probe */
|
|
if (icsk->icsk_mtup.probe_size) {
|
|
icsk->icsk_mtup.probe_size = 0;
|
|
}
|
|
|
|
/* Do not sent more than we queued. 1/4 is reserved for possible
|
|
* copying overhead: fragmentation, 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 (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
|
|
return -EHOSTUNREACH; /* Routing failure or similar. */
|
|
|
|
cur_mss = tcp_current_mss(sk);
|
|
|
|
/* 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, tcp_wnd_end(tp)) &&
|
|
TCP_SKB_CB(skb)->seq != tp->snd_una)
|
|
return -EAGAIN;
|
|
|
|
if (skb->len > cur_mss) {
|
|
if (tcp_fragment(sk, skb, cur_mss, cur_mss))
|
|
return -ENOMEM; /* We'll try again later. */
|
|
} else {
|
|
int oldpcount = tcp_skb_pcount(skb);
|
|
|
|
if (unlikely(oldpcount > 1)) {
|
|
tcp_init_tso_segs(sk, skb, cur_mss);
|
|
tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb));
|
|
}
|
|
}
|
|
|
|
tcp_retrans_try_collapse(sk, skb, cur_mss);
|
|
|
|
/* 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)->tcp_flags & TCPHDR_FIN) &&
|
|
tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) {
|
|
if (!pskb_trim(skb, 0)) {
|
|
/* Reuse, even though it does some unnecessary work */
|
|
tcp_init_nondata_skb(skb, TCP_SKB_CB(skb)->end_seq - 1,
|
|
TCP_SKB_CB(skb)->tcp_flags);
|
|
skb->ip_summed = CHECKSUM_NONE;
|
|
}
|
|
}
|
|
|
|
/* 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, 1, GFP_ATOMIC);
|
|
|
|
if (err == 0) {
|
|
/* Update global TCP statistics. */
|
|
TCP_INC_STATS(sock_net(sk), 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
|
|
if (!tp->retrans_out)
|
|
tp->lost_retrans_low = tp->snd_nxt;
|
|
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 += tcp_skb_pcount(skb);
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/* Check if we forward retransmits are possible in the current
|
|
* window/congestion state.
|
|
*/
|
|
static int tcp_can_forward_retransmit(struct sock *sk)
|
|
{
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
/* Forward retransmissions are possible only during Recovery. */
|
|
if (icsk->icsk_ca_state != TCP_CA_Recovery)
|
|
return 0;
|
|
|
|
/* No forward retransmissions in Reno are possible. */
|
|
if (tcp_is_reno(tp))
|
|
return 0;
|
|
|
|
/* 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. In the other cases, follow rule 3 for
|
|
* NextSeg() specified in RFC3517.
|
|
*/
|
|
|
|
if (tcp_may_send_now(sk))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* 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;
|
|
struct sk_buff *hole = NULL;
|
|
u32 last_lost;
|
|
int mib_idx;
|
|
int fwd_rexmitting = 0;
|
|
|
|
if (!tp->packets_out)
|
|
return;
|
|
|
|
if (!tp->lost_out)
|
|
tp->retransmit_high = tp->snd_una;
|
|
|
|
if (tp->retransmit_skb_hint) {
|
|
skb = tp->retransmit_skb_hint;
|
|
last_lost = TCP_SKB_CB(skb)->end_seq;
|
|
if (after(last_lost, tp->retransmit_high))
|
|
last_lost = tp->retransmit_high;
|
|
} else {
|
|
skb = tcp_write_queue_head(sk);
|
|
last_lost = tp->snd_una;
|
|
}
|
|
|
|
tcp_for_write_queue_from(skb, sk) {
|
|
__u8 sacked = TCP_SKB_CB(skb)->sacked;
|
|
|
|
if (skb == tcp_send_head(sk))
|
|
break;
|
|
/* we could do better than to assign each time */
|
|
if (hole == NULL)
|
|
tp->retransmit_skb_hint = skb;
|
|
|
|
/* 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 (fwd_rexmitting) {
|
|
begin_fwd:
|
|
if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
|
|
break;
|
|
mib_idx = LINUX_MIB_TCPFORWARDRETRANS;
|
|
|
|
} else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) {
|
|
tp->retransmit_high = last_lost;
|
|
if (!tcp_can_forward_retransmit(sk))
|
|
break;
|
|
/* Backtrack if necessary to non-L'ed skb */
|
|
if (hole != NULL) {
|
|
skb = hole;
|
|
hole = NULL;
|
|
}
|
|
fwd_rexmitting = 1;
|
|
goto begin_fwd;
|
|
|
|
} else if (!(sacked & TCPCB_LOST)) {
|
|
if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED)))
|
|
hole = skb;
|
|
continue;
|
|
|
|
} else {
|
|
last_lost = TCP_SKB_CB(skb)->end_seq;
|
|
if (icsk->icsk_ca_state != TCP_CA_Loss)
|
|
mib_idx = LINUX_MIB_TCPFASTRETRANS;
|
|
else
|
|
mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
|
|
}
|
|
|
|
if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
|
|
continue;
|
|
|
|
if (tcp_retransmit_skb(sk, skb))
|
|
return;
|
|
NET_INC_STATS_BH(sock_net(sk), mib_idx);
|
|
|
|
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery)
|
|
tp->prr_out += tcp_skb_pcount(skb);
|
|
|
|
if (skb == tcp_write_queue_head(sk))
|
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
|
|
inet_csk(sk)->icsk_rto,
|
|
TCP_RTO_MAX);
|
|
}
|
|
}
|
|
|
|
/* 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 = tcp_write_queue_tail(sk);
|
|
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);
|
|
|
|
if (tcp_send_head(sk) != NULL) {
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
|
|
TCP_SKB_CB(skb)->end_seq++;
|
|
tp->write_seq++;
|
|
} else {
|
|
/* Socket is locked, keep trying until memory is available. */
|
|
for (;;) {
|
|
skb = alloc_skb_fclone(MAX_TCP_HEADER,
|
|
sk->sk_allocation);
|
|
if (skb)
|
|
break;
|
|
yield();
|
|
}
|
|
|
|
/* Reserve space for headers and prepare control bits. */
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
|
|
tcp_init_nondata_skb(skb, tp->write_seq,
|
|
TCPHDR_ACK | TCPHDR_FIN);
|
|
tcp_queue_skb(sk, skb);
|
|
}
|
|
__tcp_push_pending_frames(sk, 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 RFC 2525, section 2.17. -DaveM
|
|
*/
|
|
void tcp_send_active_reset(struct sock *sk, gfp_t priority)
|
|
{
|
|
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(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
|
|
return;
|
|
}
|
|
|
|
/* Reserve space for headers and prepare control bits. */
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk),
|
|
TCPHDR_ACK | TCPHDR_RST);
|
|
/* Send it off. */
|
|
TCP_SKB_CB(skb)->when = tcp_time_stamp;
|
|
if (tcp_transmit_skb(sk, skb, 0, priority))
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
|
|
|
|
TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS);
|
|
}
|
|
|
|
/* Send a crossed SYN-ACK during socket establishment.
|
|
* 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 = tcp_write_queue_head(sk);
|
|
if (skb == NULL || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
|
|
printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n");
|
|
return -EFAULT;
|
|
}
|
|
if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) {
|
|
if (skb_cloned(skb)) {
|
|
struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
|
|
if (nskb == NULL)
|
|
return -ENOMEM;
|
|
tcp_unlink_write_queue(skb, sk);
|
|
skb_header_release(nskb);
|
|
__tcp_add_write_queue_head(sk, nskb);
|
|
sk_wmem_free_skb(sk, skb);
|
|
sk->sk_wmem_queued += nskb->truesize;
|
|
sk_mem_charge(sk, nskb->truesize);
|
|
skb = nskb;
|
|
}
|
|
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK;
|
|
TCP_ECN_send_synack(tcp_sk(sk), skb);
|
|
}
|
|
TCP_SKB_CB(skb)->when = tcp_time_stamp;
|
|
return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
|
|
}
|
|
|
|
/* Prepare a SYN-ACK. */
|
|
struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
|
|
struct request_sock *req,
|
|
struct request_values *rvp)
|
|
{
|
|
struct tcp_out_options opts;
|
|
struct tcp_extend_values *xvp = tcp_xv(rvp);
|
|
struct inet_request_sock *ireq = inet_rsk(req);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct tcp_cookie_values *cvp = tp->cookie_values;
|
|
struct tcphdr *th;
|
|
struct sk_buff *skb;
|
|
struct tcp_md5sig_key *md5;
|
|
int tcp_header_size;
|
|
int mss;
|
|
int s_data_desired = 0;
|
|
|
|
if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired)
|
|
s_data_desired = cvp->s_data_desired;
|
|
skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15 + s_data_desired, 1, GFP_ATOMIC);
|
|
if (skb == NULL)
|
|
return NULL;
|
|
|
|
/* Reserve space for headers. */
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
|
|
skb_dst_set(skb, dst_clone(dst));
|
|
|
|
mss = dst_metric_advmss(dst);
|
|
if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss)
|
|
mss = tp->rx_opt.user_mss;
|
|
|
|
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);
|
|
|
|
/* limit the window selection if the user enforce a smaller rx buffer */
|
|
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK &&
|
|
(req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0))
|
|
req->window_clamp = tcp_full_space(sk);
|
|
|
|
/* tcp_full_space because it is guaranteed to be the first packet */
|
|
tcp_select_initial_window(tcp_full_space(sk),
|
|
mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
|
|
&req->rcv_wnd,
|
|
&req->window_clamp,
|
|
ireq->wscale_ok,
|
|
&rcv_wscale,
|
|
dst_metric(dst, RTAX_INITRWND));
|
|
ireq->rcv_wscale = rcv_wscale;
|
|
}
|
|
|
|
memset(&opts, 0, sizeof(opts));
|
|
#ifdef CONFIG_SYN_COOKIES
|
|
if (unlikely(req->cookie_ts))
|
|
TCP_SKB_CB(skb)->when = cookie_init_timestamp(req);
|
|
else
|
|
#endif
|
|
TCP_SKB_CB(skb)->when = tcp_time_stamp;
|
|
tcp_header_size = tcp_synack_options(sk, req, mss,
|
|
skb, &opts, &md5, xvp)
|
|
+ sizeof(*th);
|
|
|
|
skb_push(skb, tcp_header_size);
|
|
skb_reset_transport_header(skb);
|
|
|
|
th = tcp_hdr(skb);
|
|
memset(th, 0, sizeof(struct tcphdr));
|
|
th->syn = 1;
|
|
th->ack = 1;
|
|
TCP_ECN_make_synack(req, th);
|
|
th->source = ireq->loc_port;
|
|
th->dest = ireq->rmt_port;
|
|
/* Setting of flags are superfluous here for callers (and ECE is
|
|
* not even correctly set)
|
|
*/
|
|
tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn,
|
|
TCPHDR_SYN | TCPHDR_ACK);
|
|
|
|
if (OPTION_COOKIE_EXTENSION & opts.options) {
|
|
if (s_data_desired) {
|
|
u8 *buf = skb_put(skb, s_data_desired);
|
|
|
|
/* copy data directly from the listening socket. */
|
|
memcpy(buf, cvp->s_data_payload, s_data_desired);
|
|
TCP_SKB_CB(skb)->end_seq += s_data_desired;
|
|
}
|
|
|
|
if (opts.hash_size > 0) {
|
|
__u32 workspace[SHA_WORKSPACE_WORDS];
|
|
u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS];
|
|
u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1];
|
|
|
|
/* Secret recipe depends on the Timestamp, (future)
|
|
* Sequence and Acknowledgment Numbers, Initiator
|
|
* Cookie, and others handled by IP variant caller.
|
|
*/
|
|
*tail-- ^= opts.tsval;
|
|
*tail-- ^= tcp_rsk(req)->rcv_isn + 1;
|
|
*tail-- ^= TCP_SKB_CB(skb)->seq + 1;
|
|
|
|
/* recommended */
|
|
*tail-- ^= (((__force u32)th->dest << 16) | (__force u32)th->source);
|
|
*tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */
|
|
|
|
sha_transform((__u32 *)&xvp->cookie_bakery[0],
|
|
(char *)mess,
|
|
&workspace[0]);
|
|
opts.hash_location =
|
|
(__u8 *)&xvp->cookie_bakery[0];
|
|
}
|
|
}
|
|
|
|
th->seq = htonl(TCP_SKB_CB(skb)->seq);
|
|
th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
|
|
|
|
/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
|
|
th->window = htons(min(req->rcv_wnd, 65535U));
|
|
tcp_options_write((__be32 *)(th + 1), tp, &opts);
|
|
th->doff = (tcp_header_size >> 2);
|
|
TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb));
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
/* Okay, we have all we need - do the md5 hash if needed */
|
|
if (md5) {
|
|
tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
|
|
md5, NULL, req, skb);
|
|
}
|
|
#endif
|
|
|
|
return skb;
|
|
}
|
|
EXPORT_SYMBOL(tcp_make_synack);
|
|
|
|
/* Do all connect socket setups that can be done AF independent. */
|
|
static void tcp_connect_init(struct sock *sk)
|
|
{
|
|
const 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);
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
if (tp->af_specific->md5_lookup(sk, sk) != NULL)
|
|
tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
|
|
#endif
|
|
|
|
/* 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_mtup_init(sk);
|
|
tcp_sync_mss(sk, dst_mtu(dst));
|
|
|
|
if (!tp->window_clamp)
|
|
tp->window_clamp = dst_metric(dst, RTAX_WINDOW);
|
|
tp->advmss = dst_metric_advmss(dst);
|
|
if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss)
|
|
tp->advmss = tp->rx_opt.user_mss;
|
|
|
|
tcp_initialize_rcv_mss(sk);
|
|
|
|
/* limit the window selection if the user enforce a smaller rx buffer */
|
|
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK &&
|
|
(tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0))
|
|
tp->window_clamp = tcp_full_space(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,
|
|
dst_metric(dst, RTAX_INITRWND));
|
|
|
|
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, 0);
|
|
tp->snd_una = tp->write_seq;
|
|
tp->snd_sml = tp->write_seq;
|
|
tp->snd_up = 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;
|
|
int err;
|
|
|
|
tcp_connect_init(sk);
|
|
|
|
buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation);
|
|
if (unlikely(buff == NULL))
|
|
return -ENOBUFS;
|
|
|
|
/* Reserve space for headers. */
|
|
skb_reserve(buff, MAX_TCP_HEADER);
|
|
|
|
tp->snd_nxt = tp->write_seq;
|
|
tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN);
|
|
TCP_ECN_send_syn(sk, buff);
|
|
|
|
/* Send it off. */
|
|
TCP_SKB_CB(buff)->when = tcp_time_stamp;
|
|
tp->retrans_stamp = TCP_SKB_CB(buff)->when;
|
|
skb_header_release(buff);
|
|
__tcp_add_write_queue_tail(sk, buff);
|
|
sk->sk_wmem_queued += buff->truesize;
|
|
sk_mem_charge(sk, buff->truesize);
|
|
tp->packets_out += tcp_skb_pcount(buff);
|
|
err = tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
|
|
if (err == -ECONNREFUSED)
|
|
return err;
|
|
|
|
/* We change tp->snd_nxt after the tcp_transmit_skb() call
|
|
* in order to make this packet get counted in tcpOutSegs.
|
|
*/
|
|
tp->snd_nxt = tp->write_seq;
|
|
tp->pushed_seq = tp->write_seq;
|
|
TCP_INC_STATS(sock_net(sk), 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;
|
|
}
|
|
EXPORT_SYMBOL(tcp_connect);
|
|
|
|
/* 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)
|
|
{
|
|
struct sk_buff *buff;
|
|
|
|
/* If we have been reset, we may not send again. */
|
|
if (sk->sk_state == TCP_CLOSE)
|
|
return;
|
|
|
|
/* 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);
|
|
tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK);
|
|
|
|
/* Send it off, this clears delayed acks for us. */
|
|
TCP_SKB_CB(buff)->when = tcp_time_stamp;
|
|
tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);
|
|
}
|
|
|
|
/* 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);
|
|
/* Use a previous sequence. This should cause the other
|
|
* end to send an ack. Don't queue or clone SKB, just
|
|
* send it.
|
|
*/
|
|
tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK);
|
|
TCP_SKB_CB(skb)->when = tcp_time_stamp;
|
|
return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);
|
|
}
|
|
|
|
/* Initiate keepalive or window probe from timer. */
|
|
int tcp_write_wakeup(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb;
|
|
|
|
if (sk->sk_state == TCP_CLOSE)
|
|
return -1;
|
|
|
|
if ((skb = tcp_send_head(sk)) != NULL &&
|
|
before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) {
|
|
int err;
|
|
unsigned int mss = tcp_current_mss(sk);
|
|
unsigned int seg_size = tcp_wnd_end(tp) - 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)->tcp_flags |= TCPHDR_PSH;
|
|
if (tcp_fragment(sk, skb, seg_size, mss))
|
|
return -1;
|
|
} else if (!tcp_skb_pcount(skb))
|
|
tcp_set_skb_tso_segs(sk, skb, mss);
|
|
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
|
|
TCP_SKB_CB(skb)->when = tcp_time_stamp;
|
|
err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
|
|
if (!err)
|
|
tcp_event_new_data_sent(sk, skb);
|
|
return err;
|
|
} else {
|
|
if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF))
|
|
tcp_xmit_probe_skb(sk, 1);
|
|
return tcp_xmit_probe_skb(sk, 0);
|
|
}
|
|
}
|
|
|
|
/* 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 || !tcp_send_head(sk)) {
|
|
/* 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);
|
|
}
|
|
}
|