2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
6 * Implementation of the Transmission Control Protocol(TCP).
8 * Version: $Id: tcp.c,v 1.216 2002/02/01 22:01:04 davem Exp $
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Mark Evans, <evansmp@uhura.aston.ac.uk>
13 * Corey Minyard <wf-rch!minyard@relay.EU.net>
14 * Florian La Roche, <flla@stud.uni-sb.de>
15 * Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
16 * Linus Torvalds, <torvalds@cs.helsinki.fi>
17 * Alan Cox, <gw4pts@gw4pts.ampr.org>
18 * Matthew Dillon, <dillon@apollo.west.oic.com>
19 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
20 * Jorge Cwik, <jorge@laser.satlink.net>
23 * Alan Cox : Numerous verify_area() calls
24 * Alan Cox : Set the ACK bit on a reset
25 * Alan Cox : Stopped it crashing if it closed while
26 * sk->inuse=1 and was trying to connect
28 * Alan Cox : All icmp error handling was broken
29 * pointers passed where wrong and the
30 * socket was looked up backwards. Nobody
31 * tested any icmp error code obviously.
32 * Alan Cox : tcp_err() now handled properly. It
33 * wakes people on errors. poll
34 * behaves and the icmp error race
35 * has gone by moving it into sock.c
36 * Alan Cox : tcp_send_reset() fixed to work for
37 * everything not just packets for
39 * Alan Cox : tcp option processing.
40 * Alan Cox : Reset tweaked (still not 100%) [Had
42 * Herp Rosmanith : More reset fixes
43 * Alan Cox : No longer acks invalid rst frames.
44 * Acking any kind of RST is right out.
45 * Alan Cox : Sets an ignore me flag on an rst
46 * receive otherwise odd bits of prattle
48 * Alan Cox : Fixed another acking RST frame bug.
49 * Should stop LAN workplace lockups.
50 * Alan Cox : Some tidyups using the new skb list
52 * Alan Cox : sk->keepopen now seems to work
53 * Alan Cox : Pulls options out correctly on accepts
54 * Alan Cox : Fixed assorted sk->rqueue->next errors
55 * Alan Cox : PSH doesn't end a TCP read. Switched a
57 * Alan Cox : Tidied tcp_data to avoid a potential
59 * Alan Cox : Added some better commenting, as the
60 * tcp is hard to follow
61 * Alan Cox : Removed incorrect check for 20 * psh
62 * Michael O'Reilly : ack < copied bug fix.
63 * Johannes Stille : Misc tcp fixes (not all in yet).
64 * Alan Cox : FIN with no memory -> CRASH
65 * Alan Cox : Added socket option proto entries.
66 * Also added awareness of them to accept.
67 * Alan Cox : Added TCP options (SOL_TCP)
68 * Alan Cox : Switched wakeup calls to callbacks,
69 * so the kernel can layer network
71 * Alan Cox : Use ip_tos/ip_ttl settings.
72 * Alan Cox : Handle FIN (more) properly (we hope).
73 * Alan Cox : RST frames sent on unsynchronised
75 * Alan Cox : Put in missing check for SYN bit.
76 * Alan Cox : Added tcp_select_window() aka NET2E
77 * window non shrink trick.
78 * Alan Cox : Added a couple of small NET2E timer
80 * Charles Hedrick : TCP fixes
81 * Toomas Tamm : TCP window fixes
82 * Alan Cox : Small URG fix to rlogin ^C ack fight
83 * Charles Hedrick : Rewrote most of it to actually work
84 * Linus : Rewrote tcp_read() and URG handling
86 * Gerhard Koerting: Fixed some missing timer handling
87 * Matthew Dillon : Reworked TCP machine states as per RFC
88 * Gerhard Koerting: PC/TCP workarounds
89 * Adam Caldwell : Assorted timer/timing errors
90 * Matthew Dillon : Fixed another RST bug
91 * Alan Cox : Move to kernel side addressing changes.
92 * Alan Cox : Beginning work on TCP fastpathing
94 * Arnt Gulbrandsen: Turbocharged tcp_check() routine.
95 * Alan Cox : TCP fast path debugging
96 * Alan Cox : Window clamping
97 * Michael Riepe : Bug in tcp_check()
98 * Matt Dillon : More TCP improvements and RST bug fixes
99 * Matt Dillon : Yet more small nasties remove from the
100 * TCP code (Be very nice to this man if
101 * tcp finally works 100%) 8)
102 * Alan Cox : BSD accept semantics.
103 * Alan Cox : Reset on closedown bug.
104 * Peter De Schrijver : ENOTCONN check missing in tcp_sendto().
105 * Michael Pall : Handle poll() after URG properly in
107 * Michael Pall : Undo the last fix in tcp_read_urg()
108 * (multi URG PUSH broke rlogin).
109 * Michael Pall : Fix the multi URG PUSH problem in
110 * tcp_readable(), poll() after URG
112 * Michael Pall : recv(...,MSG_OOB) never blocks in the
114 * Alan Cox : Changed the semantics of sk->socket to
115 * fix a race and a signal problem with
116 * accept() and async I/O.
117 * Alan Cox : Relaxed the rules on tcp_sendto().
118 * Yury Shevchuk : Really fixed accept() blocking problem.
119 * Craig I. Hagan : Allow for BSD compatible TIME_WAIT for
120 * clients/servers which listen in on
122 * Alan Cox : Cleaned the above up and shrank it to
123 * a sensible code size.
124 * Alan Cox : Self connect lockup fix.
125 * Alan Cox : No connect to multicast.
126 * Ross Biro : Close unaccepted children on master
128 * Alan Cox : Reset tracing code.
129 * Alan Cox : Spurious resets on shutdown.
130 * Alan Cox : Giant 15 minute/60 second timer error
131 * Alan Cox : Small whoops in polling before an
133 * Alan Cox : Kept the state trace facility since
134 * it's handy for debugging.
135 * Alan Cox : More reset handler fixes.
136 * Alan Cox : Started rewriting the code based on
137 * the RFC's for other useful protocol
138 * references see: Comer, KA9Q NOS, and
139 * for a reference on the difference
140 * between specifications and how BSD
141 * works see the 4.4lite source.
142 * A.N.Kuznetsov : Don't time wait on completion of tidy
144 * Linus Torvalds : Fin/Shutdown & copied_seq changes.
145 * Linus Torvalds : Fixed BSD port reuse to work first syn
146 * Alan Cox : Reimplemented timers as per the RFC
147 * and using multiple timers for sanity.
148 * Alan Cox : Small bug fixes, and a lot of new
150 * Alan Cox : Fixed dual reader crash by locking
151 * the buffers (much like datagram.c)
152 * Alan Cox : Fixed stuck sockets in probe. A probe
153 * now gets fed up of retrying without
154 * (even a no space) answer.
155 * Alan Cox : Extracted closing code better
156 * Alan Cox : Fixed the closing state machine to
158 * Alan Cox : More 'per spec' fixes.
159 * Jorge Cwik : Even faster checksumming.
160 * Alan Cox : tcp_data() doesn't ack illegal PSH
161 * only frames. At least one pc tcp stack
163 * Alan Cox : Cache last socket.
164 * Alan Cox : Per route irtt.
165 * Matt Day : poll()->select() match BSD precisely on error
166 * Alan Cox : New buffers
167 * Marc Tamsky : Various sk->prot->retransmits and
168 * sk->retransmits misupdating fixed.
169 * Fixed tcp_write_timeout: stuck close,
170 * and TCP syn retries gets used now.
171 * Mark Yarvis : In tcp_read_wakeup(), don't send an
172 * ack if state is TCP_CLOSED.
173 * Alan Cox : Look up device on a retransmit - routes may
174 * change. Doesn't yet cope with MSS shrink right
176 * Marc Tamsky : Closing in closing fixes.
177 * Mike Shaver : RFC1122 verifications.
178 * Alan Cox : rcv_saddr errors.
179 * Alan Cox : Block double connect().
180 * Alan Cox : Small hooks for enSKIP.
181 * Alexey Kuznetsov: Path MTU discovery.
182 * Alan Cox : Support soft errors.
183 * Alan Cox : Fix MTU discovery pathological case
184 * when the remote claims no mtu!
185 * Marc Tamsky : TCP_CLOSE fix.
186 * Colin (G3TNE) : Send a reset on syn ack replies in
187 * window but wrong (fixes NT lpd problems)
188 * Pedro Roque : Better TCP window handling, delayed ack.
189 * Joerg Reuter : No modification of locked buffers in
190 * tcp_do_retransmit()
191 * Eric Schenk : Changed receiver side silly window
192 * avoidance algorithm to BSD style
193 * algorithm. This doubles throughput
194 * against machines running Solaris,
195 * and seems to result in general
197 * Stefan Magdalinski : adjusted tcp_readable() to fix FIONREAD
198 * Willy Konynenberg : Transparent proxying support.
199 * Mike McLagan : Routing by source
200 * Keith Owens : Do proper merging with partial SKB's in
201 * tcp_do_sendmsg to avoid burstiness.
202 * Eric Schenk : Fix fast close down bug with
203 * shutdown() followed by close().
204 * Andi Kleen : Make poll agree with SIGIO
205 * Salvatore Sanfilippo : Support SO_LINGER with linger == 1 and
206 * lingertime == 0 (RFC 793 ABORT Call)
207 * Hirokazu Takahashi : Use copy_from_user() instead of
208 * csum_and_copy_from_user() if possible.
210 * This program is free software; you can redistribute it and/or
211 * modify it under the terms of the GNU General Public License
212 * as published by the Free Software Foundation; either version
213 * 2 of the License, or(at your option) any later version.
215 * Description of States:
217 * TCP_SYN_SENT sent a connection request, waiting for ack
219 * TCP_SYN_RECV received a connection request, sent ack,
220 * waiting for final ack in three-way handshake.
222 * TCP_ESTABLISHED connection established
224 * TCP_FIN_WAIT1 our side has shutdown, waiting to complete
225 * transmission of remaining buffered data
227 * TCP_FIN_WAIT2 all buffered data sent, waiting for remote
230 * TCP_CLOSING both sides have shutdown but we still have
231 * data we have to finish sending
233 * TCP_TIME_WAIT timeout to catch resent junk before entering
234 * closed, can only be entered from FIN_WAIT2
235 * or CLOSING. Required because the other end
236 * may not have gotten our last ACK causing it
237 * to retransmit the data packet (which we ignore)
239 * TCP_CLOSE_WAIT remote side has shutdown and is waiting for
240 * us to finish writing our data and to shutdown
241 * (we have to close() to move on to LAST_ACK)
243 * TCP_LAST_ACK out side has shutdown after remote has
244 * shutdown. There may still be data in our
245 * buffer that we have to finish sending
247 * TCP_CLOSE socket is finished
250 #include <linux/config.h>
251 #include <linux/module.h>
252 #include <linux/types.h>
253 #include <linux/fcntl.h>
254 #include <linux/poll.h>
255 #include <linux/init.h>
256 #include <linux/smp_lock.h>
257 #include <linux/fs.h>
258 #include <linux/random.h>
259 #include <linux/bootmem.h>
260 #include <linux/cache.h>
261 #include <linux/err.h>
263 #include <net/icmp.h>
265 #include <net/xfrm.h>
269 #include <asm/uaccess.h>
270 #include <asm/ioctls.h>
272 int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
274 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
276 atomic_t tcp_orphan_count = ATOMIC_INIT(0);
278 EXPORT_SYMBOL_GPL(tcp_orphan_count);
280 int sysctl_tcp_mem[3] __read_mostly;
281 int sysctl_tcp_wmem[3] __read_mostly;
282 int sysctl_tcp_rmem[3] __read_mostly;
284 EXPORT_SYMBOL(sysctl_tcp_mem);
285 EXPORT_SYMBOL(sysctl_tcp_rmem);
286 EXPORT_SYMBOL(sysctl_tcp_wmem);
288 atomic_t tcp_memory_allocated; /* Current allocated memory. */
289 atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */
291 EXPORT_SYMBOL(tcp_memory_allocated);
292 EXPORT_SYMBOL(tcp_sockets_allocated);
295 * Pressure flag: try to collapse.
296 * Technical note: it is used by multiple contexts non atomically.
297 * All the sk_stream_mem_schedule() is of this nature: accounting
298 * is strict, actions are advisory and have some latency.
300 int tcp_memory_pressure;
302 EXPORT_SYMBOL(tcp_memory_pressure);
304 void tcp_enter_memory_pressure(void)
306 if (!tcp_memory_pressure) {
307 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
308 tcp_memory_pressure = 1;
312 EXPORT_SYMBOL(tcp_enter_memory_pressure);
315 * Wait for a TCP event.
317 * Note that we don't need to lock the socket, as the upper poll layers
318 * take care of normal races (between the test and the event) and we don't
319 * go look at any of the socket buffers directly.
321 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
324 struct sock *sk = sock->sk;
325 struct tcp_sock *tp = tcp_sk(sk);
327 poll_wait(file, sk->sk_sleep, wait);
328 if (sk->sk_state == TCP_LISTEN)
329 return inet_csk_listen_poll(sk);
331 /* Socket is not locked. We are protected from async events
332 by poll logic and correct handling of state changes
333 made by another threads is impossible in any case.
341 * POLLHUP is certainly not done right. But poll() doesn't
342 * have a notion of HUP in just one direction, and for a
343 * socket the read side is more interesting.
345 * Some poll() documentation says that POLLHUP is incompatible
346 * with the POLLOUT/POLLWR flags, so somebody should check this
347 * all. But careful, it tends to be safer to return too many
348 * bits than too few, and you can easily break real applications
349 * if you don't tell them that something has hung up!
353 * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
354 * our fs/select.c). It means that after we received EOF,
355 * poll always returns immediately, making impossible poll() on write()
356 * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
357 * if and only if shutdown has been made in both directions.
358 * Actually, it is interesting to look how Solaris and DUX
359 * solve this dilemma. I would prefer, if PULLHUP were maskable,
360 * then we could set it on SND_SHUTDOWN. BTW examples given
361 * in Stevens' books assume exactly this behaviour, it explains
362 * why PULLHUP is incompatible with POLLOUT. --ANK
364 * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
365 * blocking on fresh not-connected or disconnected socket. --ANK
367 if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
369 if (sk->sk_shutdown & RCV_SHUTDOWN)
370 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
373 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
374 /* Potential race condition. If read of tp below will
375 * escape above sk->sk_state, we can be illegally awaken
376 * in SYN_* states. */
377 if ((tp->rcv_nxt != tp->copied_seq) &&
378 (tp->urg_seq != tp->copied_seq ||
379 tp->rcv_nxt != tp->copied_seq + 1 ||
380 sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))
381 mask |= POLLIN | POLLRDNORM;
383 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
384 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
385 mask |= POLLOUT | POLLWRNORM;
386 } else { /* send SIGIO later */
387 set_bit(SOCK_ASYNC_NOSPACE,
388 &sk->sk_socket->flags);
389 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
391 /* Race breaker. If space is freed after
392 * wspace test but before the flags are set,
393 * IO signal will be lost.
395 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
396 mask |= POLLOUT | POLLWRNORM;
400 if (tp->urg_data & TCP_URG_VALID)
406 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
408 struct tcp_sock *tp = tcp_sk(sk);
413 if (sk->sk_state == TCP_LISTEN)
417 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
419 else if (sock_flag(sk, SOCK_URGINLINE) ||
421 before(tp->urg_seq, tp->copied_seq) ||
422 !before(tp->urg_seq, tp->rcv_nxt)) {
423 answ = tp->rcv_nxt - tp->copied_seq;
425 /* Subtract 1, if FIN is in queue. */
426 if (answ && !skb_queue_empty(&sk->sk_receive_queue))
428 ((struct sk_buff *)sk->sk_receive_queue.prev)->h.th->fin;
430 answ = tp->urg_seq - tp->copied_seq;
434 answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
437 if (sk->sk_state == TCP_LISTEN)
440 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
443 answ = tp->write_seq - tp->snd_una;
449 return put_user(answ, (int __user *)arg);
452 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
454 TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
455 tp->pushed_seq = tp->write_seq;
458 static inline int forced_push(struct tcp_sock *tp)
460 return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
463 static inline void skb_entail(struct sock *sk, struct tcp_sock *tp,
467 TCP_SKB_CB(skb)->seq = tp->write_seq;
468 TCP_SKB_CB(skb)->end_seq = tp->write_seq;
469 TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;
470 TCP_SKB_CB(skb)->sacked = 0;
471 skb_header_release(skb);
472 __skb_queue_tail(&sk->sk_write_queue, skb);
473 sk_charge_skb(sk, skb);
474 if (!sk->sk_send_head)
475 sk->sk_send_head = skb;
476 if (tp->nonagle & TCP_NAGLE_PUSH)
477 tp->nonagle &= ~TCP_NAGLE_PUSH;
480 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
483 if (flags & MSG_OOB) {
485 tp->snd_up = tp->write_seq;
486 TCP_SKB_CB(skb)->sacked |= TCPCB_URG;
490 static inline void tcp_push(struct sock *sk, struct tcp_sock *tp, int flags,
491 int mss_now, int nonagle)
493 if (sk->sk_send_head) {
494 struct sk_buff *skb = sk->sk_write_queue.prev;
495 if (!(flags & MSG_MORE) || forced_push(tp))
496 tcp_mark_push(tp, skb);
497 tcp_mark_urg(tp, flags, skb);
498 __tcp_push_pending_frames(sk, tp, mss_now,
499 (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
503 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
504 size_t psize, int flags)
506 struct tcp_sock *tp = tcp_sk(sk);
507 int mss_now, size_goal;
510 long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
512 /* Wait for a connection to finish. */
513 if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
514 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
517 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
519 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
520 size_goal = tp->xmit_size_goal;
524 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
528 struct sk_buff *skb = sk->sk_write_queue.prev;
529 struct page *page = pages[poffset / PAGE_SIZE];
530 int copy, i, can_coalesce;
531 int offset = poffset % PAGE_SIZE;
532 int size = min_t(size_t, psize, PAGE_SIZE - offset);
534 if (!sk->sk_send_head || (copy = size_goal - skb->len) <= 0) {
536 if (!sk_stream_memory_free(sk))
537 goto wait_for_sndbuf;
539 skb = sk_stream_alloc_pskb(sk, 0, 0,
542 goto wait_for_memory;
544 skb_entail(sk, tp, skb);
551 i = skb_shinfo(skb)->nr_frags;
552 can_coalesce = skb_can_coalesce(skb, i, page, offset);
553 if (!can_coalesce && i >= MAX_SKB_FRAGS) {
554 tcp_mark_push(tp, skb);
557 if (!sk_stream_wmem_schedule(sk, copy))
558 goto wait_for_memory;
561 skb_shinfo(skb)->frags[i - 1].size += copy;
564 skb_fill_page_desc(skb, i, page, offset, copy);
568 skb->data_len += copy;
569 skb->truesize += copy;
570 sk->sk_wmem_queued += copy;
571 sk->sk_forward_alloc -= copy;
572 skb->ip_summed = CHECKSUM_HW;
573 tp->write_seq += copy;
574 TCP_SKB_CB(skb)->end_seq += copy;
575 skb_shinfo(skb)->gso_segs = 0;
578 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
582 if (!(psize -= copy))
585 if (skb->len < mss_now || (flags & MSG_OOB))
588 if (forced_push(tp)) {
589 tcp_mark_push(tp, skb);
590 __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
591 } else if (skb == sk->sk_send_head)
592 tcp_push_one(sk, mss_now);
596 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
599 tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
601 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
604 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
605 size_goal = tp->xmit_size_goal;
610 tcp_push(sk, tp, flags, mss_now, tp->nonagle);
617 return sk_stream_error(sk, flags, err);
620 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
621 size_t size, int flags)
624 struct sock *sk = sock->sk;
626 if (!(sk->sk_route_caps & NETIF_F_SG) ||
627 !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
628 return sock_no_sendpage(sock, page, offset, size, flags);
632 res = do_tcp_sendpages(sk, &page, offset, size, flags);
638 #define TCP_PAGE(sk) (sk->sk_sndmsg_page)
639 #define TCP_OFF(sk) (sk->sk_sndmsg_off)
641 static inline int select_size(struct sock *sk, struct tcp_sock *tp)
643 int tmp = tp->mss_cache;
645 if (sk->sk_route_caps & NETIF_F_SG) {
646 if (sk->sk_route_caps & NETIF_F_TSO)
649 int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
651 if (tmp >= pgbreak &&
652 tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
660 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
664 struct tcp_sock *tp = tcp_sk(sk);
667 int mss_now, size_goal;
674 flags = msg->msg_flags;
675 timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
677 /* Wait for a connection to finish. */
678 if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
679 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
682 /* This should be in poll */
683 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
685 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
686 size_goal = tp->xmit_size_goal;
688 /* Ok commence sending. */
689 iovlen = msg->msg_iovlen;
694 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
697 while (--iovlen >= 0) {
698 int seglen = iov->iov_len;
699 unsigned char __user *from = iov->iov_base;
706 skb = sk->sk_write_queue.prev;
708 if (!sk->sk_send_head ||
709 (copy = size_goal - skb->len) <= 0) {
712 /* Allocate new segment. If the interface is SG,
713 * allocate skb fitting to single page.
715 if (!sk_stream_memory_free(sk))
716 goto wait_for_sndbuf;
718 skb = sk_stream_alloc_pskb(sk, select_size(sk, tp),
719 0, sk->sk_allocation);
721 goto wait_for_memory;
724 * Check whether we can use HW checksum.
726 if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
727 skb->ip_summed = CHECKSUM_HW;
729 skb_entail(sk, tp, skb);
733 /* Try to append data to the end of skb. */
737 /* Where to copy to? */
738 if (skb_tailroom(skb) > 0) {
739 /* We have some space in skb head. Superb! */
740 if (copy > skb_tailroom(skb))
741 copy = skb_tailroom(skb);
742 if ((err = skb_add_data(skb, from, copy)) != 0)
746 int i = skb_shinfo(skb)->nr_frags;
747 struct page *page = TCP_PAGE(sk);
748 int off = TCP_OFF(sk);
750 if (skb_can_coalesce(skb, i, page, off) &&
752 /* We can extend the last page
755 } else if (i == MAX_SKB_FRAGS ||
757 !(sk->sk_route_caps & NETIF_F_SG))) {
758 /* Need to add new fragment and cannot
759 * do this because interface is non-SG,
760 * or because all the page slots are
762 tcp_mark_push(tp, skb);
765 if (off == PAGE_SIZE) {
767 TCP_PAGE(sk) = page = NULL;
773 if (copy > PAGE_SIZE - off)
774 copy = PAGE_SIZE - off;
776 if (!sk_stream_wmem_schedule(sk, copy))
777 goto wait_for_memory;
780 /* Allocate new cache page. */
781 if (!(page = sk_stream_alloc_page(sk)))
782 goto wait_for_memory;
785 /* Time to copy data. We are close to
787 err = skb_copy_to_page(sk, from, skb, page,
790 /* If this page was new, give it to the
791 * socket so it does not get leaked.
800 /* Update the skb. */
802 skb_shinfo(skb)->frags[i - 1].size +=
805 skb_fill_page_desc(skb, i, page, off, copy);
808 } else if (off + copy < PAGE_SIZE) {
814 TCP_OFF(sk) = off + copy;
818 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
820 tp->write_seq += copy;
821 TCP_SKB_CB(skb)->end_seq += copy;
822 skb_shinfo(skb)->gso_segs = 0;
826 if ((seglen -= copy) == 0 && iovlen == 0)
829 if (skb->len < mss_now || (flags & MSG_OOB))
832 if (forced_push(tp)) {
833 tcp_mark_push(tp, skb);
834 __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
835 } else if (skb == sk->sk_send_head)
836 tcp_push_one(sk, mss_now);
840 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
843 tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
845 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
848 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
849 size_goal = tp->xmit_size_goal;
855 tcp_push(sk, tp, flags, mss_now, tp->nonagle);
862 if (sk->sk_send_head == skb)
863 sk->sk_send_head = NULL;
864 __skb_unlink(skb, &sk->sk_write_queue);
865 sk_stream_free_skb(sk, skb);
872 err = sk_stream_error(sk, flags, err);
879 * Handle reading urgent data. BSD has very simple semantics for
880 * this, no blocking and very strange errors 8)
883 static int tcp_recv_urg(struct sock *sk, long timeo,
884 struct msghdr *msg, int len, int flags,
887 struct tcp_sock *tp = tcp_sk(sk);
889 /* No URG data to read. */
890 if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
891 tp->urg_data == TCP_URG_READ)
892 return -EINVAL; /* Yes this is right ! */
894 if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
897 if (tp->urg_data & TCP_URG_VALID) {
899 char c = tp->urg_data;
901 if (!(flags & MSG_PEEK))
902 tp->urg_data = TCP_URG_READ;
904 /* Read urgent data. */
905 msg->msg_flags |= MSG_OOB;
908 if (!(flags & MSG_TRUNC))
909 err = memcpy_toiovec(msg->msg_iov, &c, 1);
912 msg->msg_flags |= MSG_TRUNC;
914 return err ? -EFAULT : len;
917 if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
920 /* Fixed the recv(..., MSG_OOB) behaviour. BSD docs and
921 * the available implementations agree in this case:
922 * this call should never block, independent of the
923 * blocking state of the socket.
924 * Mike <pall@rz.uni-karlsruhe.de>
929 /* Clean up the receive buffer for full frames taken by the user,
930 * then send an ACK if necessary. COPIED is the number of bytes
931 * tcp_recvmsg has given to the user so far, it speeds up the
932 * calculation of whether or not we must ACK for the sake of
935 void cleanup_rbuf(struct sock *sk, int copied)
937 struct tcp_sock *tp = tcp_sk(sk);
941 struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
943 BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
946 if (inet_csk_ack_scheduled(sk)) {
947 const struct inet_connection_sock *icsk = inet_csk(sk);
948 /* Delayed ACKs frequently hit locked sockets during bulk
950 if (icsk->icsk_ack.blocked ||
951 /* Once-per-two-segments ACK was not sent by tcp_input.c */
952 tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
954 * If this read emptied read buffer, we send ACK, if
955 * connection is not bidirectional, user drained
956 * receive buffer and there was a small segment
959 (copied > 0 && (icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
960 !icsk->icsk_ack.pingpong && !atomic_read(&sk->sk_rmem_alloc)))
964 /* We send an ACK if we can now advertise a non-zero window
965 * which has been raised "significantly".
967 * Even if window raised up to infinity, do not send window open ACK
968 * in states, where we will not receive more. It is useless.
970 if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
971 __u32 rcv_window_now = tcp_receive_window(tp);
973 /* Optimize, __tcp_select_window() is not cheap. */
974 if (2*rcv_window_now <= tp->window_clamp) {
975 __u32 new_window = __tcp_select_window(sk);
977 /* Send ACK now, if this read freed lots of space
978 * in our buffer. Certainly, new_window is new window.
979 * We can advertise it now, if it is not less than current one.
980 * "Lots" means "at least twice" here.
982 if (new_window && new_window >= 2 * rcv_window_now)
990 static void tcp_prequeue_process(struct sock *sk)
993 struct tcp_sock *tp = tcp_sk(sk);
995 NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
997 /* RX process wants to run with disabled BHs, though it is not
1000 while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
1001 sk->sk_backlog_rcv(sk, skb);
1004 /* Clear memory counter. */
1005 tp->ucopy.memory = 0;
1008 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
1010 struct sk_buff *skb;
1013 skb_queue_walk(&sk->sk_receive_queue, skb) {
1014 offset = seq - TCP_SKB_CB(skb)->seq;
1017 if (offset < skb->len || skb->h.th->fin) {
1026 * This routine provides an alternative to tcp_recvmsg() for routines
1027 * that would like to handle copying from skbuffs directly in 'sendfile'
1030 * - It is assumed that the socket was locked by the caller.
1031 * - The routine does not block.
1032 * - At present, there is no support for reading OOB data
1033 * or for 'peeking' the socket using this routine
1034 * (although both would be easy to implement).
1036 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
1037 sk_read_actor_t recv_actor)
1039 struct sk_buff *skb;
1040 struct tcp_sock *tp = tcp_sk(sk);
1041 u32 seq = tp->copied_seq;
1045 if (sk->sk_state == TCP_LISTEN)
1047 while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
1048 if (offset < skb->len) {
1051 len = skb->len - offset;
1052 /* Stop reading if we hit a patch of urgent data */
1054 u32 urg_offset = tp->urg_seq - seq;
1055 if (urg_offset < len)
1060 used = recv_actor(desc, skb, offset, len);
1066 if (offset != skb->len)
1069 if (skb->h.th->fin) {
1070 sk_eat_skb(sk, skb);
1074 sk_eat_skb(sk, skb);
1078 tp->copied_seq = seq;
1080 tcp_rcv_space_adjust(sk);
1082 /* Clean up data we have read: This will do ACK frames. */
1084 cleanup_rbuf(sk, copied);
1089 * This routine copies from a sock struct into the user buffer.
1091 * Technical note: in 2.3 we work on _locked_ socket, so that
1092 * tricks with *seq access order and skb->users are not required.
1093 * Probably, code can be easily improved even more.
1096 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
1097 size_t len, int nonblock, int flags, int *addr_len)
1099 struct tcp_sock *tp = tcp_sk(sk);
1105 int target; /* Read at least this many bytes */
1107 struct task_struct *user_recv = NULL;
1111 TCP_CHECK_TIMER(sk);
1114 if (sk->sk_state == TCP_LISTEN)
1117 timeo = sock_rcvtimeo(sk, nonblock);
1119 /* Urgent data needs to be handled specially. */
1120 if (flags & MSG_OOB)
1123 seq = &tp->copied_seq;
1124 if (flags & MSG_PEEK) {
1125 peek_seq = tp->copied_seq;
1129 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
1132 struct sk_buff *skb;
1135 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1136 if (tp->urg_data && tp->urg_seq == *seq) {
1139 if (signal_pending(current)) {
1140 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
1145 /* Next get a buffer. */
1147 skb = skb_peek(&sk->sk_receive_queue);
1152 /* Now that we have two receive queues this
1155 if (before(*seq, TCP_SKB_CB(skb)->seq)) {
1156 printk(KERN_INFO "recvmsg bug: copied %X "
1157 "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
1160 offset = *seq - TCP_SKB_CB(skb)->seq;
1163 if (offset < skb->len)
1167 BUG_TRAP(flags & MSG_PEEK);
1169 } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
1171 /* Well, if we have backlog, try to process it now yet. */
1173 if (copied >= target && !sk->sk_backlog.tail)
1178 sk->sk_state == TCP_CLOSE ||
1179 (sk->sk_shutdown & RCV_SHUTDOWN) ||
1181 signal_pending(current) ||
1185 if (sock_flag(sk, SOCK_DONE))
1189 copied = sock_error(sk);
1193 if (sk->sk_shutdown & RCV_SHUTDOWN)
1196 if (sk->sk_state == TCP_CLOSE) {
1197 if (!sock_flag(sk, SOCK_DONE)) {
1198 /* This occurs when user tries to read
1199 * from never connected socket.
1212 if (signal_pending(current)) {
1213 copied = sock_intr_errno(timeo);
1218 cleanup_rbuf(sk, copied);
1220 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
1221 /* Install new reader */
1222 if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
1223 user_recv = current;
1224 tp->ucopy.task = user_recv;
1225 tp->ucopy.iov = msg->msg_iov;
1228 tp->ucopy.len = len;
1230 BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
1231 (flags & (MSG_PEEK | MSG_TRUNC)));
1233 /* Ugly... If prequeue is not empty, we have to
1234 * process it before releasing socket, otherwise
1235 * order will be broken at second iteration.
1236 * More elegant solution is required!!!
1238 * Look: we have the following (pseudo)queues:
1240 * 1. packets in flight
1245 * Each queue can be processed only if the next ones
1246 * are empty. At this point we have empty receive_queue.
1247 * But prequeue _can_ be not empty after 2nd iteration,
1248 * when we jumped to start of loop because backlog
1249 * processing added something to receive_queue.
1250 * We cannot release_sock(), because backlog contains
1251 * packets arrived _after_ prequeued ones.
1253 * Shortly, algorithm is clear --- to process all
1254 * the queues in order. We could make it more directly,
1255 * requeueing packets from backlog to prequeue, if
1256 * is not empty. It is more elegant, but eats cycles,
1259 if (!skb_queue_empty(&tp->ucopy.prequeue))
1262 /* __ Set realtime policy in scheduler __ */
1265 if (copied >= target) {
1266 /* Do not sleep, just process backlog. */
1270 sk_wait_data(sk, &timeo);
1275 /* __ Restore normal policy in scheduler __ */
1277 if ((chunk = len - tp->ucopy.len) != 0) {
1278 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
1283 if (tp->rcv_nxt == tp->copied_seq &&
1284 !skb_queue_empty(&tp->ucopy.prequeue)) {
1286 tcp_prequeue_process(sk);
1288 if ((chunk = len - tp->ucopy.len) != 0) {
1289 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1295 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
1296 if (net_ratelimit())
1297 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1298 current->comm, current->pid);
1299 peek_seq = tp->copied_seq;
1304 /* Ok so how much can we use? */
1305 used = skb->len - offset;
1309 /* Do we have urgent data here? */
1311 u32 urg_offset = tp->urg_seq - *seq;
1312 if (urg_offset < used) {
1314 if (!sock_flag(sk, SOCK_URGINLINE)) {
1326 if (!(flags & MSG_TRUNC)) {
1327 err = skb_copy_datagram_iovec(skb, offset,
1328 msg->msg_iov, used);
1330 /* Exception. Bailout! */
1341 tcp_rcv_space_adjust(sk);
1344 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
1346 tcp_fast_path_check(sk, tp);
1348 if (used + offset < skb->len)
1353 if (!(flags & MSG_PEEK))
1354 sk_eat_skb(sk, skb);
1358 /* Process the FIN. */
1360 if (!(flags & MSG_PEEK))
1361 sk_eat_skb(sk, skb);
1366 if (!skb_queue_empty(&tp->ucopy.prequeue)) {
1369 tp->ucopy.len = copied > 0 ? len : 0;
1371 tcp_prequeue_process(sk);
1373 if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
1374 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
1380 tp->ucopy.task = NULL;
1384 /* According to UNIX98, msg_name/msg_namelen are ignored
1385 * on connected socket. I was just happy when found this 8) --ANK
1388 /* Clean up data we have read: This will do ACK frames. */
1389 cleanup_rbuf(sk, copied);
1391 TCP_CHECK_TIMER(sk);
1396 TCP_CHECK_TIMER(sk);
1401 err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
1406 * State processing on a close. This implements the state shift for
1407 * sending our FIN frame. Note that we only send a FIN for some
1408 * states. A shutdown() may have already sent the FIN, or we may be
1412 static const unsigned char new_state[16] = {
1413 /* current state: new state: action: */
1414 /* (Invalid) */ TCP_CLOSE,
1415 /* TCP_ESTABLISHED */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1416 /* TCP_SYN_SENT */ TCP_CLOSE,
1417 /* TCP_SYN_RECV */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
1418 /* TCP_FIN_WAIT1 */ TCP_FIN_WAIT1,
1419 /* TCP_FIN_WAIT2 */ TCP_FIN_WAIT2,
1420 /* TCP_TIME_WAIT */ TCP_CLOSE,
1421 /* TCP_CLOSE */ TCP_CLOSE,
1422 /* TCP_CLOSE_WAIT */ TCP_LAST_ACK | TCP_ACTION_FIN,
1423 /* TCP_LAST_ACK */ TCP_LAST_ACK,
1424 /* TCP_LISTEN */ TCP_CLOSE,
1425 /* TCP_CLOSING */ TCP_CLOSING,
1428 static int tcp_close_state(struct sock *sk)
1430 int next = (int)new_state[sk->sk_state];
1431 int ns = next & TCP_STATE_MASK;
1433 tcp_set_state(sk, ns);
1435 return next & TCP_ACTION_FIN;
1439 * Shutdown the sending side of a connection. Much like close except
1440 * that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
1443 void tcp_shutdown(struct sock *sk, int how)
1445 /* We need to grab some memory, and put together a FIN,
1446 * and then put it into the queue to be sent.
1447 * Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1449 if (!(how & SEND_SHUTDOWN))
1452 /* If we've already sent a FIN, or it's a closed state, skip this. */
1453 if ((1 << sk->sk_state) &
1454 (TCPF_ESTABLISHED | TCPF_SYN_SENT |
1455 TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
1456 /* Clear out any half completed packets. FIN if needed. */
1457 if (tcp_close_state(sk))
1462 void tcp_close(struct sock *sk, long timeout)
1464 struct sk_buff *skb;
1465 int data_was_unread = 0;
1469 sk->sk_shutdown = SHUTDOWN_MASK;
1471 if (sk->sk_state == TCP_LISTEN) {
1472 tcp_set_state(sk, TCP_CLOSE);
1475 inet_csk_listen_stop(sk);
1477 goto adjudge_to_death;
1480 /* We need to flush the recv. buffs. We do this only on the
1481 * descriptor close, not protocol-sourced closes, because the
1482 * reader process may not have drained the data yet!
1484 while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1485 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
1487 data_was_unread += len;
1491 sk_stream_mem_reclaim(sk);
1493 /* As outlined in draft-ietf-tcpimpl-prob-03.txt, section
1494 * 3.10, we send a RST here because data was lost. To
1495 * witness the awful effects of the old behavior of always
1496 * doing a FIN, run an older 2.1.x kernel or 2.0.x, start
1497 * a bulk GET in an FTP client, suspend the process, wait
1498 * for the client to advertise a zero window, then kill -9
1499 * the FTP client, wheee... Note: timeout is always zero
1502 if (data_was_unread) {
1503 /* Unread data was tossed, zap the connection. */
1504 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
1505 tcp_set_state(sk, TCP_CLOSE);
1506 tcp_send_active_reset(sk, GFP_KERNEL);
1507 } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1508 /* Check zero linger _after_ checking for unread data. */
1509 sk->sk_prot->disconnect(sk, 0);
1510 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
1511 } else if (tcp_close_state(sk)) {
1512 /* We FIN if the application ate all the data before
1513 * zapping the connection.
1516 /* RED-PEN. Formally speaking, we have broken TCP state
1517 * machine. State transitions:
1519 * TCP_ESTABLISHED -> TCP_FIN_WAIT1
1520 * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
1521 * TCP_CLOSE_WAIT -> TCP_LAST_ACK
1523 * are legal only when FIN has been sent (i.e. in window),
1524 * rather than queued out of window. Purists blame.
1526 * F.e. "RFC state" is ESTABLISHED,
1527 * if Linux state is FIN-WAIT-1, but FIN is still not sent.
1529 * The visible declinations are that sometimes
1530 * we enter time-wait state, when it is not required really
1531 * (harmless), do not send active resets, when they are
1532 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
1533 * they look as CLOSING or LAST_ACK for Linux)
1534 * Probably, I missed some more holelets.
1540 sk_stream_wait_close(sk, timeout);
1543 state = sk->sk_state;
1546 atomic_inc(sk->sk_prot->orphan_count);
1548 /* It is the last release_sock in its life. It will remove backlog. */
1552 /* Now socket is owned by kernel and we acquire BH lock
1553 to finish close. No need to check for user refs.
1557 BUG_TRAP(!sock_owned_by_user(sk));
1559 /* Have we already been destroyed by a softirq or backlog? */
1560 if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
1563 /* This is a (useful) BSD violating of the RFC. There is a
1564 * problem with TCP as specified in that the other end could
1565 * keep a socket open forever with no application left this end.
1566 * We use a 3 minute timeout (about the same as BSD) then kill
1567 * our end. If they send after that then tough - BUT: long enough
1568 * that we won't make the old 4*rto = almost no time - whoops
1571 * Nope, it was not mistake. It is really desired behaviour
1572 * f.e. on http servers, when such sockets are useless, but
1573 * consume significant resources. Let's do it with special
1574 * linger2 option. --ANK
1577 if (sk->sk_state == TCP_FIN_WAIT2) {
1578 struct tcp_sock *tp = tcp_sk(sk);
1579 if (tp->linger2 < 0) {
1580 tcp_set_state(sk, TCP_CLOSE);
1581 tcp_send_active_reset(sk, GFP_ATOMIC);
1582 NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
1584 const int tmo = tcp_fin_time(sk);
1586 if (tmo > TCP_TIMEWAIT_LEN) {
1587 inet_csk_reset_keepalive_timer(sk, tcp_fin_time(sk));
1589 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
1594 if (sk->sk_state != TCP_CLOSE) {
1595 sk_stream_mem_reclaim(sk);
1596 if (atomic_read(sk->sk_prot->orphan_count) > sysctl_tcp_max_orphans ||
1597 (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
1598 atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) {
1599 if (net_ratelimit())
1600 printk(KERN_INFO "TCP: too many of orphaned "
1602 tcp_set_state(sk, TCP_CLOSE);
1603 tcp_send_active_reset(sk, GFP_ATOMIC);
1604 NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
1608 if (sk->sk_state == TCP_CLOSE)
1609 inet_csk_destroy_sock(sk);
1610 /* Otherwise, socket is reprieved until protocol close. */
1618 /* These states need RST on ABORT according to RFC793 */
1620 static inline int tcp_need_reset(int state)
1622 return (1 << state) &
1623 (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
1624 TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
1627 int tcp_disconnect(struct sock *sk, int flags)
1629 struct inet_sock *inet = inet_sk(sk);
1630 struct inet_connection_sock *icsk = inet_csk(sk);
1631 struct tcp_sock *tp = tcp_sk(sk);
1633 int old_state = sk->sk_state;
1635 if (old_state != TCP_CLOSE)
1636 tcp_set_state(sk, TCP_CLOSE);
1638 /* ABORT function of RFC793 */
1639 if (old_state == TCP_LISTEN) {
1640 inet_csk_listen_stop(sk);
1641 } else if (tcp_need_reset(old_state) ||
1642 (tp->snd_nxt != tp->write_seq &&
1643 (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
1644 /* The last check adjusts for discrepancy of Linux wrt. RFC
1647 tcp_send_active_reset(sk, gfp_any());
1648 sk->sk_err = ECONNRESET;
1649 } else if (old_state == TCP_SYN_SENT)
1650 sk->sk_err = ECONNRESET;
1652 tcp_clear_xmit_timers(sk);
1653 __skb_queue_purge(&sk->sk_receive_queue);
1654 sk_stream_writequeue_purge(sk);
1655 __skb_queue_purge(&tp->out_of_order_queue);
1659 if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
1660 inet_reset_saddr(sk);
1662 sk->sk_shutdown = 0;
1663 sock_reset_flag(sk, SOCK_DONE);
1665 if ((tp->write_seq += tp->max_window + 2) == 0)
1667 icsk->icsk_backoff = 0;
1669 icsk->icsk_probes_out = 0;
1670 tp->packets_out = 0;
1671 tp->snd_ssthresh = 0x7fffffff;
1672 tp->snd_cwnd_cnt = 0;
1673 tp->bytes_acked = 0;
1674 tcp_set_ca_state(sk, TCP_CA_Open);
1675 tcp_clear_retrans(tp);
1676 inet_csk_delack_init(sk);
1677 sk->sk_send_head = NULL;
1678 tp->rx_opt.saw_tstamp = 0;
1679 tcp_sack_reset(&tp->rx_opt);
1682 BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
1684 sk->sk_error_report(sk);
1689 * Socket option code for TCP.
1691 static int do_tcp_setsockopt(struct sock *sk, int level,
1692 int optname, char __user *optval, int optlen)
1694 struct tcp_sock *tp = tcp_sk(sk);
1695 struct inet_connection_sock *icsk = inet_csk(sk);
1699 /* This is a string value all the others are int's */
1700 if (optname == TCP_CONGESTION) {
1701 char name[TCP_CA_NAME_MAX];
1706 val = strncpy_from_user(name, optval,
1707 min(TCP_CA_NAME_MAX-1, optlen));
1713 err = tcp_set_congestion_control(sk, name);
1718 if (optlen < sizeof(int))
1721 if (get_user(val, (int __user *)optval))
1728 /* Values greater than interface MTU won't take effect. However
1729 * at the point when this call is done we typically don't yet
1730 * know which interface is going to be used */
1731 if (val < 8 || val > MAX_TCP_WINDOW) {
1735 tp->rx_opt.user_mss = val;
1740 /* TCP_NODELAY is weaker than TCP_CORK, so that
1741 * this option on corked socket is remembered, but
1742 * it is not activated until cork is cleared.
1744 * However, when TCP_NODELAY is set we make
1745 * an explicit push, which overrides even TCP_CORK
1746 * for currently queued segments.
1748 tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
1749 tcp_push_pending_frames(sk, tp);
1751 tp->nonagle &= ~TCP_NAGLE_OFF;
1756 /* When set indicates to always queue non-full frames.
1757 * Later the user clears this option and we transmit
1758 * any pending partial frames in the queue. This is
1759 * meant to be used alongside sendfile() to get properly
1760 * filled frames when the user (for example) must write
1761 * out headers with a write() call first and then use
1762 * sendfile to send out the data parts.
1764 * TCP_CORK can be set together with TCP_NODELAY and it is
1765 * stronger than TCP_NODELAY.
1768 tp->nonagle |= TCP_NAGLE_CORK;
1770 tp->nonagle &= ~TCP_NAGLE_CORK;
1771 if (tp->nonagle&TCP_NAGLE_OFF)
1772 tp->nonagle |= TCP_NAGLE_PUSH;
1773 tcp_push_pending_frames(sk, tp);
1778 if (val < 1 || val > MAX_TCP_KEEPIDLE)
1781 tp->keepalive_time = val * HZ;
1782 if (sock_flag(sk, SOCK_KEEPOPEN) &&
1783 !((1 << sk->sk_state) &
1784 (TCPF_CLOSE | TCPF_LISTEN))) {
1785 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
1786 if (tp->keepalive_time > elapsed)
1787 elapsed = tp->keepalive_time - elapsed;
1790 inet_csk_reset_keepalive_timer(sk, elapsed);
1795 if (val < 1 || val > MAX_TCP_KEEPINTVL)
1798 tp->keepalive_intvl = val * HZ;
1801 if (val < 1 || val > MAX_TCP_KEEPCNT)
1804 tp->keepalive_probes = val;
1807 if (val < 1 || val > MAX_TCP_SYNCNT)
1810 icsk->icsk_syn_retries = val;
1816 else if (val > sysctl_tcp_fin_timeout / HZ)
1819 tp->linger2 = val * HZ;
1822 case TCP_DEFER_ACCEPT:
1823 icsk->icsk_accept_queue.rskq_defer_accept = 0;
1825 /* Translate value in seconds to number of
1827 while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
1828 val > ((TCP_TIMEOUT_INIT / HZ) <<
1829 icsk->icsk_accept_queue.rskq_defer_accept))
1830 icsk->icsk_accept_queue.rskq_defer_accept++;
1831 icsk->icsk_accept_queue.rskq_defer_accept++;
1835 case TCP_WINDOW_CLAMP:
1837 if (sk->sk_state != TCP_CLOSE) {
1841 tp->window_clamp = 0;
1843 tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
1844 SOCK_MIN_RCVBUF / 2 : val;
1849 icsk->icsk_ack.pingpong = 1;
1851 icsk->icsk_ack.pingpong = 0;
1852 if ((1 << sk->sk_state) &
1853 (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
1854 inet_csk_ack_scheduled(sk)) {
1855 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
1856 cleanup_rbuf(sk, 1);
1858 icsk->icsk_ack.pingpong = 1;
1871 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
1874 struct inet_connection_sock *icsk = inet_csk(sk);
1876 if (level != SOL_TCP)
1877 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1879 return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1882 #ifdef CONFIG_COMPAT
1883 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
1884 char __user *optval, int optlen)
1886 if (level != SOL_TCP)
1887 return inet_csk_compat_setsockopt(sk, level, optname,
1889 return do_tcp_setsockopt(sk, level, optname, optval, optlen);
1892 EXPORT_SYMBOL(compat_tcp_setsockopt);
1895 /* Return information about state of tcp endpoint in API format. */
1896 void tcp_get_info(struct sock *sk, struct tcp_info *info)
1898 struct tcp_sock *tp = tcp_sk(sk);
1899 const struct inet_connection_sock *icsk = inet_csk(sk);
1900 u32 now = tcp_time_stamp;
1902 memset(info, 0, sizeof(*info));
1904 info->tcpi_state = sk->sk_state;
1905 info->tcpi_ca_state = icsk->icsk_ca_state;
1906 info->tcpi_retransmits = icsk->icsk_retransmits;
1907 info->tcpi_probes = icsk->icsk_probes_out;
1908 info->tcpi_backoff = icsk->icsk_backoff;
1910 if (tp->rx_opt.tstamp_ok)
1911 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
1912 if (tp->rx_opt.sack_ok)
1913 info->tcpi_options |= TCPI_OPT_SACK;
1914 if (tp->rx_opt.wscale_ok) {
1915 info->tcpi_options |= TCPI_OPT_WSCALE;
1916 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
1917 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
1920 if (tp->ecn_flags&TCP_ECN_OK)
1921 info->tcpi_options |= TCPI_OPT_ECN;
1923 info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
1924 info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
1925 info->tcpi_snd_mss = tp->mss_cache;
1926 info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
1928 info->tcpi_unacked = tp->packets_out;
1929 info->tcpi_sacked = tp->sacked_out;
1930 info->tcpi_lost = tp->lost_out;
1931 info->tcpi_retrans = tp->retrans_out;
1932 info->tcpi_fackets = tp->fackets_out;
1934 info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
1935 info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
1936 info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
1938 info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
1939 info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
1940 info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
1941 info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
1942 info->tcpi_snd_ssthresh = tp->snd_ssthresh;
1943 info->tcpi_snd_cwnd = tp->snd_cwnd;
1944 info->tcpi_advmss = tp->advmss;
1945 info->tcpi_reordering = tp->reordering;
1947 info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
1948 info->tcpi_rcv_space = tp->rcvq_space.space;
1950 info->tcpi_total_retrans = tp->total_retrans;
1953 EXPORT_SYMBOL_GPL(tcp_get_info);
1955 static int do_tcp_getsockopt(struct sock *sk, int level,
1956 int optname, char __user *optval, int __user *optlen)
1958 struct inet_connection_sock *icsk = inet_csk(sk);
1959 struct tcp_sock *tp = tcp_sk(sk);
1962 if (get_user(len, optlen))
1965 len = min_t(unsigned int, len, sizeof(int));
1972 val = tp->mss_cache;
1973 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
1974 val = tp->rx_opt.user_mss;
1977 val = !!(tp->nonagle&TCP_NAGLE_OFF);
1980 val = !!(tp->nonagle&TCP_NAGLE_CORK);
1983 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
1986 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
1989 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1992 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
1997 val = (val ? : sysctl_tcp_fin_timeout) / HZ;
1999 case TCP_DEFER_ACCEPT:
2000 val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
2001 ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
2003 case TCP_WINDOW_CLAMP:
2004 val = tp->window_clamp;
2007 struct tcp_info info;
2009 if (get_user(len, optlen))
2012 tcp_get_info(sk, &info);
2014 len = min_t(unsigned int, len, sizeof(info));
2015 if (put_user(len, optlen))
2017 if (copy_to_user(optval, &info, len))
2022 val = !icsk->icsk_ack.pingpong;
2025 case TCP_CONGESTION:
2026 if (get_user(len, optlen))
2028 len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
2029 if (put_user(len, optlen))
2031 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
2035 return -ENOPROTOOPT;
2038 if (put_user(len, optlen))
2040 if (copy_to_user(optval, &val, len))
2045 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
2048 struct inet_connection_sock *icsk = inet_csk(sk);
2050 if (level != SOL_TCP)
2051 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
2053 return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2056 #ifdef CONFIG_COMPAT
2057 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
2058 char __user *optval, int __user *optlen)
2060 if (level != SOL_TCP)
2061 return inet_csk_compat_getsockopt(sk, level, optname,
2063 return do_tcp_getsockopt(sk, level, optname, optval, optlen);
2066 EXPORT_SYMBOL(compat_tcp_getsockopt);
2069 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
2071 struct sk_buff *segs = ERR_PTR(-EINVAL);
2076 unsigned int oldlen;
2079 if (!pskb_may_pull(skb, sizeof(*th)))
2083 thlen = th->doff * 4;
2084 if (thlen < sizeof(*th))
2087 if (!pskb_may_pull(skb, thlen))
2090 oldlen = (u16)~skb->len;
2091 __skb_pull(skb, thlen);
2093 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
2094 /* Packet is from an untrusted source, reset gso_segs. */
2095 int mss = skb_shinfo(skb)->gso_size;
2097 skb_shinfo(skb)->gso_segs = (skb->len + mss - 1) / mss;
2103 segs = skb_segment(skb, features);
2107 len = skb_shinfo(skb)->gso_size;
2108 delta = htonl(oldlen + (thlen + len));
2112 seq = ntohl(th->seq);
2115 th->fin = th->psh = 0;
2117 th->check = ~csum_fold(th->check + delta);
2118 if (skb->ip_summed != CHECKSUM_HW)
2119 th->check = csum_fold(csum_partial(skb->h.raw, thlen,
2126 th->seq = htonl(seq);
2128 } while (skb->next);
2130 delta = htonl(oldlen + (skb->tail - skb->h.raw) + skb->data_len);
2131 th->check = ~csum_fold(th->check + delta);
2132 if (skb->ip_summed != CHECKSUM_HW)
2133 th->check = csum_fold(csum_partial(skb->h.raw, thlen,
2140 extern void __skb_cb_too_small_for_tcp(int, int);
2141 extern struct tcp_congestion_ops tcp_reno;
2143 static __initdata unsigned long thash_entries;
2144 static int __init set_thash_entries(char *str)
2148 thash_entries = simple_strtoul(str, &str, 0);
2151 __setup("thash_entries=", set_thash_entries);
2153 void __init tcp_init(void)
2155 struct sk_buff *skb = NULL;
2156 unsigned long limit;
2157 int order, i, max_share;
2159 if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb))
2160 __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
2163 tcp_hashinfo.bind_bucket_cachep =
2164 kmem_cache_create("tcp_bind_bucket",
2165 sizeof(struct inet_bind_bucket), 0,
2166 SLAB_HWCACHE_ALIGN, NULL, NULL);
2167 if (!tcp_hashinfo.bind_bucket_cachep)
2168 panic("tcp_init: Cannot alloc tcp_bind_bucket cache.");
2170 /* Size and allocate the main established and bind bucket
2173 * The methodology is similar to that of the buffer cache.
2175 tcp_hashinfo.ehash =
2176 alloc_large_system_hash("TCP established",
2177 sizeof(struct inet_ehash_bucket),
2179 (num_physpages >= 128 * 1024) ?
2182 &tcp_hashinfo.ehash_size,
2185 tcp_hashinfo.ehash_size = (1 << tcp_hashinfo.ehash_size) >> 1;
2186 for (i = 0; i < (tcp_hashinfo.ehash_size << 1); i++) {
2187 rwlock_init(&tcp_hashinfo.ehash[i].lock);
2188 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
2191 tcp_hashinfo.bhash =
2192 alloc_large_system_hash("TCP bind",
2193 sizeof(struct inet_bind_hashbucket),
2194 tcp_hashinfo.ehash_size,
2195 (num_physpages >= 128 * 1024) ?
2198 &tcp_hashinfo.bhash_size,
2201 tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
2202 for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
2203 spin_lock_init(&tcp_hashinfo.bhash[i].lock);
2204 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
2207 /* Try to be a bit smarter and adjust defaults depending
2208 * on available memory.
2210 for (order = 0; ((1 << order) << PAGE_SHIFT) <
2211 (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
2215 sysctl_local_port_range[0] = 32768;
2216 sysctl_local_port_range[1] = 61000;
2217 tcp_death_row.sysctl_max_tw_buckets = 180000;
2218 sysctl_tcp_max_orphans = 4096 << (order - 4);
2219 sysctl_max_syn_backlog = 1024;
2220 } else if (order < 3) {
2221 sysctl_local_port_range[0] = 1024 * (3 - order);
2222 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
2223 sysctl_tcp_max_orphans >>= (3 - order);
2224 sysctl_max_syn_backlog = 128;
2227 sysctl_tcp_mem[0] = 768 << order;
2228 sysctl_tcp_mem[1] = 1024 << order;
2229 sysctl_tcp_mem[2] = 1536 << order;
2231 limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
2232 max_share = min(4UL*1024*1024, limit);
2234 sysctl_tcp_wmem[0] = SK_STREAM_MEM_QUANTUM;
2235 sysctl_tcp_wmem[1] = 16*1024;
2236 sysctl_tcp_wmem[2] = max(64*1024, max_share);
2238 sysctl_tcp_rmem[0] = SK_STREAM_MEM_QUANTUM;
2239 sysctl_tcp_rmem[1] = 87380;
2240 sysctl_tcp_rmem[2] = max(87380, max_share);
2242 printk(KERN_INFO "TCP: Hash tables configured "
2243 "(established %d bind %d)\n",
2244 tcp_hashinfo.ehash_size << 1, tcp_hashinfo.bhash_size);
2246 tcp_register_congestion_control(&tcp_reno);
2249 EXPORT_SYMBOL(tcp_close);
2250 EXPORT_SYMBOL(tcp_disconnect);
2251 EXPORT_SYMBOL(tcp_getsockopt);
2252 EXPORT_SYMBOL(tcp_ioctl);
2253 EXPORT_SYMBOL(tcp_poll);
2254 EXPORT_SYMBOL(tcp_read_sock);
2255 EXPORT_SYMBOL(tcp_recvmsg);
2256 EXPORT_SYMBOL(tcp_sendmsg);
2257 EXPORT_SYMBOL(tcp_sendpage);
2258 EXPORT_SYMBOL(tcp_setsockopt);
2259 EXPORT_SYMBOL(tcp_shutdown);
2260 EXPORT_SYMBOL(tcp_statistics);
2261 EXPORT_SYMBOL_GPL(cleanup_rbuf);