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>
261 #include <net/icmp.h>
263 #include <net/xfrm.h>
267 #include <asm/uaccess.h>
268 #include <asm/ioctls.h>
270 int sysctl_tcp_fin_timeout
= TCP_FIN_TIMEOUT
;
272 DEFINE_SNMP_STAT(struct tcp_mib
, tcp_statistics
) __read_mostly
;
274 atomic_t tcp_orphan_count
= ATOMIC_INIT(0);
276 EXPORT_SYMBOL_GPL(tcp_orphan_count
);
278 int sysctl_tcp_mem
[3];
279 int sysctl_tcp_wmem
[3] = { 4 * 1024, 16 * 1024, 128 * 1024 };
280 int sysctl_tcp_rmem
[3] = { 4 * 1024, 87380, 87380 * 2 };
282 EXPORT_SYMBOL(sysctl_tcp_mem
);
283 EXPORT_SYMBOL(sysctl_tcp_rmem
);
284 EXPORT_SYMBOL(sysctl_tcp_wmem
);
286 atomic_t tcp_memory_allocated
; /* Current allocated memory. */
287 atomic_t tcp_sockets_allocated
; /* Current number of TCP sockets. */
289 EXPORT_SYMBOL(tcp_memory_allocated
);
290 EXPORT_SYMBOL(tcp_sockets_allocated
);
293 * Pressure flag: try to collapse.
294 * Technical note: it is used by multiple contexts non atomically.
295 * All the sk_stream_mem_schedule() is of this nature: accounting
296 * is strict, actions are advisory and have some latency.
298 int tcp_memory_pressure
;
300 EXPORT_SYMBOL(tcp_memory_pressure
);
302 void tcp_enter_memory_pressure(void)
304 if (!tcp_memory_pressure
) {
305 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES
);
306 tcp_memory_pressure
= 1;
310 EXPORT_SYMBOL(tcp_enter_memory_pressure
);
313 * Wait for a TCP event.
315 * Note that we don't need to lock the socket, as the upper poll layers
316 * take care of normal races (between the test and the event) and we don't
317 * go look at any of the socket buffers directly.
319 unsigned int tcp_poll(struct file
*file
, struct socket
*sock
, poll_table
*wait
)
322 struct sock
*sk
= sock
->sk
;
323 struct tcp_sock
*tp
= tcp_sk(sk
);
325 poll_wait(file
, sk
->sk_sleep
, wait
);
326 if (sk
->sk_state
== TCP_LISTEN
)
327 return inet_csk_listen_poll(sk
);
329 /* Socket is not locked. We are protected from async events
330 by poll logic and correct handling of state changes
331 made by another threads is impossible in any case.
339 * POLLHUP is certainly not done right. But poll() doesn't
340 * have a notion of HUP in just one direction, and for a
341 * socket the read side is more interesting.
343 * Some poll() documentation says that POLLHUP is incompatible
344 * with the POLLOUT/POLLWR flags, so somebody should check this
345 * all. But careful, it tends to be safer to return too many
346 * bits than too few, and you can easily break real applications
347 * if you don't tell them that something has hung up!
351 * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
352 * our fs/select.c). It means that after we received EOF,
353 * poll always returns immediately, making impossible poll() on write()
354 * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
355 * if and only if shutdown has been made in both directions.
356 * Actually, it is interesting to look how Solaris and DUX
357 * solve this dilemma. I would prefer, if PULLHUP were maskable,
358 * then we could set it on SND_SHUTDOWN. BTW examples given
359 * in Stevens' books assume exactly this behaviour, it explains
360 * why PULLHUP is incompatible with POLLOUT. --ANK
362 * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
363 * blocking on fresh not-connected or disconnected socket. --ANK
365 if (sk
->sk_shutdown
== SHUTDOWN_MASK
|| sk
->sk_state
== TCP_CLOSE
)
367 if (sk
->sk_shutdown
& RCV_SHUTDOWN
)
368 mask
|= POLLIN
| POLLRDNORM
;
371 if ((1 << sk
->sk_state
) & ~(TCPF_SYN_SENT
| TCPF_SYN_RECV
)) {
372 /* Potential race condition. If read of tp below will
373 * escape above sk->sk_state, we can be illegally awaken
374 * in SYN_* states. */
375 if ((tp
->rcv_nxt
!= tp
->copied_seq
) &&
376 (tp
->urg_seq
!= tp
->copied_seq
||
377 tp
->rcv_nxt
!= tp
->copied_seq
+ 1 ||
378 sock_flag(sk
, SOCK_URGINLINE
) || !tp
->urg_data
))
379 mask
|= POLLIN
| POLLRDNORM
;
381 if (!(sk
->sk_shutdown
& SEND_SHUTDOWN
)) {
382 if (sk_stream_wspace(sk
) >= sk_stream_min_wspace(sk
)) {
383 mask
|= POLLOUT
| POLLWRNORM
;
384 } else { /* send SIGIO later */
385 set_bit(SOCK_ASYNC_NOSPACE
,
386 &sk
->sk_socket
->flags
);
387 set_bit(SOCK_NOSPACE
, &sk
->sk_socket
->flags
);
389 /* Race breaker. If space is freed after
390 * wspace test but before the flags are set,
391 * IO signal will be lost.
393 if (sk_stream_wspace(sk
) >= sk_stream_min_wspace(sk
))
394 mask
|= POLLOUT
| POLLWRNORM
;
398 if (tp
->urg_data
& TCP_URG_VALID
)
404 int tcp_ioctl(struct sock
*sk
, int cmd
, unsigned long arg
)
406 struct tcp_sock
*tp
= tcp_sk(sk
);
411 if (sk
->sk_state
== TCP_LISTEN
)
415 if ((1 << sk
->sk_state
) & (TCPF_SYN_SENT
| TCPF_SYN_RECV
))
417 else if (sock_flag(sk
, SOCK_URGINLINE
) ||
419 before(tp
->urg_seq
, tp
->copied_seq
) ||
420 !before(tp
->urg_seq
, tp
->rcv_nxt
)) {
421 answ
= tp
->rcv_nxt
- tp
->copied_seq
;
423 /* Subtract 1, if FIN is in queue. */
424 if (answ
&& !skb_queue_empty(&sk
->sk_receive_queue
))
426 ((struct sk_buff
*)sk
->sk_receive_queue
.prev
)->h
.th
->fin
;
428 answ
= tp
->urg_seq
- tp
->copied_seq
;
432 answ
= tp
->urg_data
&& tp
->urg_seq
== tp
->copied_seq
;
435 if (sk
->sk_state
== TCP_LISTEN
)
438 if ((1 << sk
->sk_state
) & (TCPF_SYN_SENT
| TCPF_SYN_RECV
))
441 answ
= tp
->write_seq
- tp
->snd_una
;
447 return put_user(answ
, (int __user
*)arg
);
450 static inline void tcp_mark_push(struct tcp_sock
*tp
, struct sk_buff
*skb
)
452 TCP_SKB_CB(skb
)->flags
|= TCPCB_FLAG_PSH
;
453 tp
->pushed_seq
= tp
->write_seq
;
456 static inline int forced_push(struct tcp_sock
*tp
)
458 return after(tp
->write_seq
, tp
->pushed_seq
+ (tp
->max_window
>> 1));
461 static inline void skb_entail(struct sock
*sk
, struct tcp_sock
*tp
,
465 TCP_SKB_CB(skb
)->seq
= tp
->write_seq
;
466 TCP_SKB_CB(skb
)->end_seq
= tp
->write_seq
;
467 TCP_SKB_CB(skb
)->flags
= TCPCB_FLAG_ACK
;
468 TCP_SKB_CB(skb
)->sacked
= 0;
469 skb_header_release(skb
);
470 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
471 sk_charge_skb(sk
, skb
);
472 if (!sk
->sk_send_head
)
473 sk
->sk_send_head
= skb
;
474 if (tp
->nonagle
& TCP_NAGLE_PUSH
)
475 tp
->nonagle
&= ~TCP_NAGLE_PUSH
;
478 static inline void tcp_mark_urg(struct tcp_sock
*tp
, int flags
,
481 if (flags
& MSG_OOB
) {
483 tp
->snd_up
= tp
->write_seq
;
484 TCP_SKB_CB(skb
)->sacked
|= TCPCB_URG
;
488 static inline void tcp_push(struct sock
*sk
, struct tcp_sock
*tp
, int flags
,
489 int mss_now
, int nonagle
)
491 if (sk
->sk_send_head
) {
492 struct sk_buff
*skb
= sk
->sk_write_queue
.prev
;
493 if (!(flags
& MSG_MORE
) || forced_push(tp
))
494 tcp_mark_push(tp
, skb
);
495 tcp_mark_urg(tp
, flags
, skb
);
496 __tcp_push_pending_frames(sk
, tp
, mss_now
,
497 (flags
& MSG_MORE
) ? TCP_NAGLE_CORK
: nonagle
);
501 static ssize_t
do_tcp_sendpages(struct sock
*sk
, struct page
**pages
, int poffset
,
502 size_t psize
, int flags
)
504 struct tcp_sock
*tp
= tcp_sk(sk
);
505 int mss_now
, size_goal
;
508 long timeo
= sock_sndtimeo(sk
, flags
& MSG_DONTWAIT
);
510 /* Wait for a connection to finish. */
511 if ((1 << sk
->sk_state
) & ~(TCPF_ESTABLISHED
| TCPF_CLOSE_WAIT
))
512 if ((err
= sk_stream_wait_connect(sk
, &timeo
)) != 0)
515 clear_bit(SOCK_ASYNC_NOSPACE
, &sk
->sk_socket
->flags
);
517 mss_now
= tcp_current_mss(sk
, !(flags
&MSG_OOB
));
518 size_goal
= tp
->xmit_size_goal
;
522 if (sk
->sk_err
|| (sk
->sk_shutdown
& SEND_SHUTDOWN
))
526 struct sk_buff
*skb
= sk
->sk_write_queue
.prev
;
527 struct page
*page
= pages
[poffset
/ PAGE_SIZE
];
528 int copy
, i
, can_coalesce
;
529 int offset
= poffset
% PAGE_SIZE
;
530 int size
= min_t(size_t, psize
, PAGE_SIZE
- offset
);
532 if (!sk
->sk_send_head
|| (copy
= size_goal
- skb
->len
) <= 0) {
534 if (!sk_stream_memory_free(sk
))
535 goto wait_for_sndbuf
;
537 skb
= sk_stream_alloc_pskb(sk
, 0, 0,
540 goto wait_for_memory
;
542 skb_entail(sk
, tp
, skb
);
549 i
= skb_shinfo(skb
)->nr_frags
;
550 can_coalesce
= skb_can_coalesce(skb
, i
, page
, offset
);
551 if (!can_coalesce
&& i
>= MAX_SKB_FRAGS
) {
552 tcp_mark_push(tp
, skb
);
555 if (sk
->sk_forward_alloc
< copy
&&
556 !sk_stream_mem_schedule(sk
, copy
, 0))
557 goto wait_for_memory
;
560 skb_shinfo(skb
)->frags
[i
- 1].size
+= copy
;
563 skb_fill_page_desc(skb
, i
, page
, offset
, copy
);
567 skb
->data_len
+= copy
;
568 skb
->truesize
+= copy
;
569 sk
->sk_wmem_queued
+= copy
;
570 sk
->sk_forward_alloc
-= copy
;
571 skb
->ip_summed
= CHECKSUM_HW
;
572 tp
->write_seq
+= copy
;
573 TCP_SKB_CB(skb
)->end_seq
+= copy
;
574 skb_shinfo(skb
)->tso_segs
= 0;
577 TCP_SKB_CB(skb
)->flags
&= ~TCPCB_FLAG_PSH
;
581 if (!(psize
-= copy
))
584 if (skb
->len
< mss_now
|| (flags
& MSG_OOB
))
587 if (forced_push(tp
)) {
588 tcp_mark_push(tp
, skb
);
589 __tcp_push_pending_frames(sk
, tp
, mss_now
, TCP_NAGLE_PUSH
);
590 } else if (skb
== sk
->sk_send_head
)
591 tcp_push_one(sk
, mss_now
);
595 set_bit(SOCK_NOSPACE
, &sk
->sk_socket
->flags
);
598 tcp_push(sk
, tp
, flags
& ~MSG_MORE
, mss_now
, TCP_NAGLE_PUSH
);
600 if ((err
= sk_stream_wait_memory(sk
, &timeo
)) != 0)
603 mss_now
= tcp_current_mss(sk
, !(flags
&MSG_OOB
));
604 size_goal
= tp
->xmit_size_goal
;
609 tcp_push(sk
, tp
, flags
, mss_now
, tp
->nonagle
);
616 return sk_stream_error(sk
, flags
, err
);
619 ssize_t
tcp_sendpage(struct socket
*sock
, struct page
*page
, int offset
,
620 size_t size
, int flags
)
623 struct sock
*sk
= sock
->sk
;
625 #define TCP_ZC_CSUM_FLAGS (NETIF_F_IP_CSUM | NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
627 if (!(sk
->sk_route_caps
& NETIF_F_SG
) ||
628 !(sk
->sk_route_caps
& TCP_ZC_CSUM_FLAGS
))
629 return sock_no_sendpage(sock
, page
, offset
, size
, flags
);
631 #undef TCP_ZC_CSUM_FLAGS
635 res
= do_tcp_sendpages(sk
, &page
, offset
, size
, flags
);
641 #define TCP_PAGE(sk) (sk->sk_sndmsg_page)
642 #define TCP_OFF(sk) (sk->sk_sndmsg_off)
644 static inline int select_size(struct sock
*sk
, struct tcp_sock
*tp
)
646 int tmp
= tp
->mss_cache
;
648 if (sk
->sk_route_caps
& NETIF_F_SG
) {
649 if (sk
->sk_route_caps
& NETIF_F_TSO
)
652 int pgbreak
= SKB_MAX_HEAD(MAX_TCP_HEADER
);
654 if (tmp
>= pgbreak
&&
655 tmp
<= pgbreak
+ (MAX_SKB_FRAGS
- 1) * PAGE_SIZE
)
663 int tcp_sendmsg(struct kiocb
*iocb
, struct sock
*sk
, struct msghdr
*msg
,
667 struct tcp_sock
*tp
= tcp_sk(sk
);
670 int mss_now
, size_goal
;
677 flags
= msg
->msg_flags
;
678 timeo
= sock_sndtimeo(sk
, flags
& MSG_DONTWAIT
);
680 /* Wait for a connection to finish. */
681 if ((1 << sk
->sk_state
) & ~(TCPF_ESTABLISHED
| TCPF_CLOSE_WAIT
))
682 if ((err
= sk_stream_wait_connect(sk
, &timeo
)) != 0)
685 /* This should be in poll */
686 clear_bit(SOCK_ASYNC_NOSPACE
, &sk
->sk_socket
->flags
);
688 mss_now
= tcp_current_mss(sk
, !(flags
&MSG_OOB
));
689 size_goal
= tp
->xmit_size_goal
;
691 /* Ok commence sending. */
692 iovlen
= msg
->msg_iovlen
;
697 if (sk
->sk_err
|| (sk
->sk_shutdown
& SEND_SHUTDOWN
))
700 while (--iovlen
>= 0) {
701 int seglen
= iov
->iov_len
;
702 unsigned char __user
*from
= iov
->iov_base
;
709 skb
= sk
->sk_write_queue
.prev
;
711 if (!sk
->sk_send_head
||
712 (copy
= size_goal
- skb
->len
) <= 0) {
715 /* Allocate new segment. If the interface is SG,
716 * allocate skb fitting to single page.
718 if (!sk_stream_memory_free(sk
))
719 goto wait_for_sndbuf
;
721 skb
= sk_stream_alloc_pskb(sk
, select_size(sk
, tp
),
722 0, sk
->sk_allocation
);
724 goto wait_for_memory
;
727 * Check whether we can use HW checksum.
729 if (sk
->sk_route_caps
&
730 (NETIF_F_IP_CSUM
| NETIF_F_NO_CSUM
|
732 skb
->ip_summed
= CHECKSUM_HW
;
734 skb_entail(sk
, tp
, skb
);
738 /* Try to append data to the end of skb. */
742 /* Where to copy to? */
743 if (skb_tailroom(skb
) > 0) {
744 /* We have some space in skb head. Superb! */
745 if (copy
> skb_tailroom(skb
))
746 copy
= skb_tailroom(skb
);
747 if ((err
= skb_add_data(skb
, from
, copy
)) != 0)
751 int i
= skb_shinfo(skb
)->nr_frags
;
752 struct page
*page
= TCP_PAGE(sk
);
753 int off
= TCP_OFF(sk
);
755 if (skb_can_coalesce(skb
, i
, page
, off
) &&
757 /* We can extend the last page
760 } else if (i
== MAX_SKB_FRAGS
||
762 !(sk
->sk_route_caps
& NETIF_F_SG
))) {
763 /* Need to add new fragment and cannot
764 * do this because interface is non-SG,
765 * or because all the page slots are
767 tcp_mark_push(tp
, skb
);
770 if (off
== PAGE_SIZE
) {
772 TCP_PAGE(sk
) = page
= NULL
;
777 /* Allocate new cache page. */
778 if (!(page
= sk_stream_alloc_page(sk
)))
779 goto wait_for_memory
;
783 if (copy
> PAGE_SIZE
- off
)
784 copy
= PAGE_SIZE
- off
;
786 /* Time to copy data. We are close to
788 err
= skb_copy_to_page(sk
, from
, skb
, page
,
791 /* If this page was new, give it to the
792 * socket so it does not get leaked.
801 /* Update the skb. */
803 skb_shinfo(skb
)->frags
[i
- 1].size
+=
806 skb_fill_page_desc(skb
, i
, page
, off
, copy
);
809 } else if (off
+ copy
< PAGE_SIZE
) {
815 TCP_OFF(sk
) = off
+ copy
;
819 TCP_SKB_CB(skb
)->flags
&= ~TCPCB_FLAG_PSH
;
821 tp
->write_seq
+= copy
;
822 TCP_SKB_CB(skb
)->end_seq
+= copy
;
823 skb_shinfo(skb
)->tso_segs
= 0;
827 if ((seglen
-= copy
) == 0 && iovlen
== 0)
830 if (skb
->len
< mss_now
|| (flags
& MSG_OOB
))
833 if (forced_push(tp
)) {
834 tcp_mark_push(tp
, skb
);
835 __tcp_push_pending_frames(sk
, tp
, mss_now
, TCP_NAGLE_PUSH
);
836 } else if (skb
== sk
->sk_send_head
)
837 tcp_push_one(sk
, mss_now
);
841 set_bit(SOCK_NOSPACE
, &sk
->sk_socket
->flags
);
844 tcp_push(sk
, tp
, flags
& ~MSG_MORE
, mss_now
, TCP_NAGLE_PUSH
);
846 if ((err
= sk_stream_wait_memory(sk
, &timeo
)) != 0)
849 mss_now
= tcp_current_mss(sk
, !(flags
&MSG_OOB
));
850 size_goal
= tp
->xmit_size_goal
;
856 tcp_push(sk
, tp
, flags
, mss_now
, tp
->nonagle
);
863 if (sk
->sk_send_head
== skb
)
864 sk
->sk_send_head
= NULL
;
865 __skb_unlink(skb
, &sk
->sk_write_queue
);
866 sk_stream_free_skb(sk
, skb
);
873 err
= sk_stream_error(sk
, flags
, err
);
880 * Handle reading urgent data. BSD has very simple semantics for
881 * this, no blocking and very strange errors 8)
884 static int tcp_recv_urg(struct sock
*sk
, long timeo
,
885 struct msghdr
*msg
, int len
, int flags
,
888 struct tcp_sock
*tp
= tcp_sk(sk
);
890 /* No URG data to read. */
891 if (sock_flag(sk
, SOCK_URGINLINE
) || !tp
->urg_data
||
892 tp
->urg_data
== TCP_URG_READ
)
893 return -EINVAL
; /* Yes this is right ! */
895 if (sk
->sk_state
== TCP_CLOSE
&& !sock_flag(sk
, SOCK_DONE
))
898 if (tp
->urg_data
& TCP_URG_VALID
) {
900 char c
= tp
->urg_data
;
902 if (!(flags
& MSG_PEEK
))
903 tp
->urg_data
= TCP_URG_READ
;
905 /* Read urgent data. */
906 msg
->msg_flags
|= MSG_OOB
;
909 if (!(flags
& MSG_TRUNC
))
910 err
= memcpy_toiovec(msg
->msg_iov
, &c
, 1);
913 msg
->msg_flags
|= MSG_TRUNC
;
915 return err
? -EFAULT
: len
;
918 if (sk
->sk_state
== TCP_CLOSE
|| (sk
->sk_shutdown
& RCV_SHUTDOWN
))
921 /* Fixed the recv(..., MSG_OOB) behaviour. BSD docs and
922 * the available implementations agree in this case:
923 * this call should never block, independent of the
924 * blocking state of the socket.
925 * Mike <pall@rz.uni-karlsruhe.de>
930 /* Clean up the receive buffer for full frames taken by the user,
931 * then send an ACK if necessary. COPIED is the number of bytes
932 * tcp_recvmsg has given to the user so far, it speeds up the
933 * calculation of whether or not we must ACK for the sake of
936 static void cleanup_rbuf(struct sock
*sk
, int copied
)
938 struct tcp_sock
*tp
= tcp_sk(sk
);
942 struct sk_buff
*skb
= skb_peek(&sk
->sk_receive_queue
);
944 BUG_TRAP(!skb
|| before(tp
->copied_seq
, TCP_SKB_CB(skb
)->end_seq
));
947 if (inet_csk_ack_scheduled(sk
)) {
948 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
949 /* Delayed ACKs frequently hit locked sockets during bulk
951 if (icsk
->icsk_ack
.blocked
||
952 /* Once-per-two-segments ACK was not sent by tcp_input.c */
953 tp
->rcv_nxt
- tp
->rcv_wup
> icsk
->icsk_ack
.rcv_mss
||
955 * If this read emptied read buffer, we send ACK, if
956 * connection is not bidirectional, user drained
957 * receive buffer and there was a small segment
960 (copied
> 0 && (icsk
->icsk_ack
.pending
& ICSK_ACK_PUSHED
) &&
961 !icsk
->icsk_ack
.pingpong
&& !atomic_read(&sk
->sk_rmem_alloc
)))
965 /* We send an ACK if we can now advertise a non-zero window
966 * which has been raised "significantly".
968 * Even if window raised up to infinity, do not send window open ACK
969 * in states, where we will not receive more. It is useless.
971 if (copied
> 0 && !time_to_ack
&& !(sk
->sk_shutdown
& RCV_SHUTDOWN
)) {
972 __u32 rcv_window_now
= tcp_receive_window(tp
);
974 /* Optimize, __tcp_select_window() is not cheap. */
975 if (2*rcv_window_now
<= tp
->window_clamp
) {
976 __u32 new_window
= __tcp_select_window(sk
);
978 /* Send ACK now, if this read freed lots of space
979 * in our buffer. Certainly, new_window is new window.
980 * We can advertise it now, if it is not less than current one.
981 * "Lots" means "at least twice" here.
983 if (new_window
&& new_window
>= 2 * rcv_window_now
)
991 static void tcp_prequeue_process(struct sock
*sk
)
994 struct tcp_sock
*tp
= tcp_sk(sk
);
996 NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED
);
998 /* RX process wants to run with disabled BHs, though it is not
1001 while ((skb
= __skb_dequeue(&tp
->ucopy
.prequeue
)) != NULL
)
1002 sk
->sk_backlog_rcv(sk
, skb
);
1005 /* Clear memory counter. */
1006 tp
->ucopy
.memory
= 0;
1009 static inline struct sk_buff
*tcp_recv_skb(struct sock
*sk
, u32 seq
, u32
*off
)
1011 struct sk_buff
*skb
;
1014 skb_queue_walk(&sk
->sk_receive_queue
, skb
) {
1015 offset
= seq
- TCP_SKB_CB(skb
)->seq
;
1018 if (offset
< skb
->len
|| skb
->h
.th
->fin
) {
1027 * This routine provides an alternative to tcp_recvmsg() for routines
1028 * that would like to handle copying from skbuffs directly in 'sendfile'
1031 * - It is assumed that the socket was locked by the caller.
1032 * - The routine does not block.
1033 * - At present, there is no support for reading OOB data
1034 * or for 'peeking' the socket using this routine
1035 * (although both would be easy to implement).
1037 int tcp_read_sock(struct sock
*sk
, read_descriptor_t
*desc
,
1038 sk_read_actor_t recv_actor
)
1040 struct sk_buff
*skb
;
1041 struct tcp_sock
*tp
= tcp_sk(sk
);
1042 u32 seq
= tp
->copied_seq
;
1046 if (sk
->sk_state
== TCP_LISTEN
)
1048 while ((skb
= tcp_recv_skb(sk
, seq
, &offset
)) != NULL
) {
1049 if (offset
< skb
->len
) {
1052 len
= skb
->len
- offset
;
1053 /* Stop reading if we hit a patch of urgent data */
1055 u32 urg_offset
= tp
->urg_seq
- seq
;
1056 if (urg_offset
< len
)
1061 used
= recv_actor(desc
, skb
, offset
, len
);
1067 if (offset
!= skb
->len
)
1070 if (skb
->h
.th
->fin
) {
1071 sk_eat_skb(sk
, skb
);
1075 sk_eat_skb(sk
, skb
);
1079 tp
->copied_seq
= seq
;
1081 tcp_rcv_space_adjust(sk
);
1083 /* Clean up data we have read: This will do ACK frames. */
1085 cleanup_rbuf(sk
, copied
);
1090 * This routine copies from a sock struct into the user buffer.
1092 * Technical note: in 2.3 we work on _locked_ socket, so that
1093 * tricks with *seq access order and skb->users are not required.
1094 * Probably, code can be easily improved even more.
1097 int tcp_recvmsg(struct kiocb
*iocb
, struct sock
*sk
, struct msghdr
*msg
,
1098 size_t len
, int nonblock
, int flags
, int *addr_len
)
1100 struct tcp_sock
*tp
= tcp_sk(sk
);
1106 int target
; /* Read at least this many bytes */
1108 struct task_struct
*user_recv
= NULL
;
1112 TCP_CHECK_TIMER(sk
);
1115 if (sk
->sk_state
== TCP_LISTEN
)
1118 timeo
= sock_rcvtimeo(sk
, nonblock
);
1120 /* Urgent data needs to be handled specially. */
1121 if (flags
& MSG_OOB
)
1124 seq
= &tp
->copied_seq
;
1125 if (flags
& MSG_PEEK
) {
1126 peek_seq
= tp
->copied_seq
;
1130 target
= sock_rcvlowat(sk
, flags
& MSG_WAITALL
, len
);
1133 struct sk_buff
*skb
;
1136 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
1137 if (tp
->urg_data
&& tp
->urg_seq
== *seq
) {
1140 if (signal_pending(current
)) {
1141 copied
= timeo
? sock_intr_errno(timeo
) : -EAGAIN
;
1146 /* Next get a buffer. */
1148 skb
= skb_peek(&sk
->sk_receive_queue
);
1153 /* Now that we have two receive queues this
1156 if (before(*seq
, TCP_SKB_CB(skb
)->seq
)) {
1157 printk(KERN_INFO
"recvmsg bug: copied %X "
1158 "seq %X\n", *seq
, TCP_SKB_CB(skb
)->seq
);
1161 offset
= *seq
- TCP_SKB_CB(skb
)->seq
;
1164 if (offset
< skb
->len
)
1168 BUG_TRAP(flags
& MSG_PEEK
);
1170 } while (skb
!= (struct sk_buff
*)&sk
->sk_receive_queue
);
1172 /* Well, if we have backlog, try to process it now yet. */
1174 if (copied
>= target
&& !sk
->sk_backlog
.tail
)
1179 sk
->sk_state
== TCP_CLOSE
||
1180 (sk
->sk_shutdown
& RCV_SHUTDOWN
) ||
1182 signal_pending(current
) ||
1186 if (sock_flag(sk
, SOCK_DONE
))
1190 copied
= sock_error(sk
);
1194 if (sk
->sk_shutdown
& RCV_SHUTDOWN
)
1197 if (sk
->sk_state
== TCP_CLOSE
) {
1198 if (!sock_flag(sk
, SOCK_DONE
)) {
1199 /* This occurs when user tries to read
1200 * from never connected socket.
1213 if (signal_pending(current
)) {
1214 copied
= sock_intr_errno(timeo
);
1219 cleanup_rbuf(sk
, copied
);
1221 if (!sysctl_tcp_low_latency
&& tp
->ucopy
.task
== user_recv
) {
1222 /* Install new reader */
1223 if (!user_recv
&& !(flags
& (MSG_TRUNC
| MSG_PEEK
))) {
1224 user_recv
= current
;
1225 tp
->ucopy
.task
= user_recv
;
1226 tp
->ucopy
.iov
= msg
->msg_iov
;
1229 tp
->ucopy
.len
= len
;
1231 BUG_TRAP(tp
->copied_seq
== tp
->rcv_nxt
||
1232 (flags
& (MSG_PEEK
| MSG_TRUNC
)));
1234 /* Ugly... If prequeue is not empty, we have to
1235 * process it before releasing socket, otherwise
1236 * order will be broken at second iteration.
1237 * More elegant solution is required!!!
1239 * Look: we have the following (pseudo)queues:
1241 * 1. packets in flight
1246 * Each queue can be processed only if the next ones
1247 * are empty. At this point we have empty receive_queue.
1248 * But prequeue _can_ be not empty after 2nd iteration,
1249 * when we jumped to start of loop because backlog
1250 * processing added something to receive_queue.
1251 * We cannot release_sock(), because backlog contains
1252 * packets arrived _after_ prequeued ones.
1254 * Shortly, algorithm is clear --- to process all
1255 * the queues in order. We could make it more directly,
1256 * requeueing packets from backlog to prequeue, if
1257 * is not empty. It is more elegant, but eats cycles,
1260 if (!skb_queue_empty(&tp
->ucopy
.prequeue
))
1263 /* __ Set realtime policy in scheduler __ */
1266 if (copied
>= target
) {
1267 /* Do not sleep, just process backlog. */
1271 sk_wait_data(sk
, &timeo
);
1276 /* __ Restore normal policy in scheduler __ */
1278 if ((chunk
= len
- tp
->ucopy
.len
) != 0) {
1279 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG
, chunk
);
1284 if (tp
->rcv_nxt
== tp
->copied_seq
&&
1285 !skb_queue_empty(&tp
->ucopy
.prequeue
)) {
1287 tcp_prequeue_process(sk
);
1289 if ((chunk
= len
- tp
->ucopy
.len
) != 0) {
1290 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE
, chunk
);
1296 if ((flags
& MSG_PEEK
) && peek_seq
!= tp
->copied_seq
) {
1297 if (net_ratelimit())
1298 printk(KERN_DEBUG
"TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
1299 current
->comm
, current
->pid
);
1300 peek_seq
= tp
->copied_seq
;
1305 /* Ok so how much can we use? */
1306 used
= skb
->len
- offset
;
1310 /* Do we have urgent data here? */
1312 u32 urg_offset
= tp
->urg_seq
- *seq
;
1313 if (urg_offset
< used
) {
1315 if (!sock_flag(sk
, SOCK_URGINLINE
)) {
1327 if (!(flags
& MSG_TRUNC
)) {
1328 err
= skb_copy_datagram_iovec(skb
, offset
,
1329 msg
->msg_iov
, used
);
1331 /* Exception. Bailout! */
1342 tcp_rcv_space_adjust(sk
);
1345 if (tp
->urg_data
&& after(tp
->copied_seq
, tp
->urg_seq
)) {
1347 tcp_fast_path_check(sk
, tp
);
1349 if (used
+ offset
< skb
->len
)
1354 if (!(flags
& MSG_PEEK
))
1355 sk_eat_skb(sk
, skb
);
1359 /* Process the FIN. */
1361 if (!(flags
& MSG_PEEK
))
1362 sk_eat_skb(sk
, skb
);
1367 if (!skb_queue_empty(&tp
->ucopy
.prequeue
)) {
1370 tp
->ucopy
.len
= copied
> 0 ? len
: 0;
1372 tcp_prequeue_process(sk
);
1374 if (copied
> 0 && (chunk
= len
- tp
->ucopy
.len
) != 0) {
1375 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE
, chunk
);
1381 tp
->ucopy
.task
= NULL
;
1385 /* According to UNIX98, msg_name/msg_namelen are ignored
1386 * on connected socket. I was just happy when found this 8) --ANK
1389 /* Clean up data we have read: This will do ACK frames. */
1390 cleanup_rbuf(sk
, copied
);
1392 TCP_CHECK_TIMER(sk
);
1397 TCP_CHECK_TIMER(sk
);
1402 err
= tcp_recv_urg(sk
, timeo
, msg
, len
, flags
, addr_len
);
1407 * State processing on a close. This implements the state shift for
1408 * sending our FIN frame. Note that we only send a FIN for some
1409 * states. A shutdown() may have already sent the FIN, or we may be
1413 static unsigned char new_state
[16] = {
1414 /* current state: new state: action: */
1415 /* (Invalid) */ TCP_CLOSE
,
1416 /* TCP_ESTABLISHED */ TCP_FIN_WAIT1
| TCP_ACTION_FIN
,
1417 /* TCP_SYN_SENT */ TCP_CLOSE
,
1418 /* TCP_SYN_RECV */ TCP_FIN_WAIT1
| TCP_ACTION_FIN
,
1419 /* TCP_FIN_WAIT1 */ TCP_FIN_WAIT1
,
1420 /* TCP_FIN_WAIT2 */ TCP_FIN_WAIT2
,
1421 /* TCP_TIME_WAIT */ TCP_CLOSE
,
1422 /* TCP_CLOSE */ TCP_CLOSE
,
1423 /* TCP_CLOSE_WAIT */ TCP_LAST_ACK
| TCP_ACTION_FIN
,
1424 /* TCP_LAST_ACK */ TCP_LAST_ACK
,
1425 /* TCP_LISTEN */ TCP_CLOSE
,
1426 /* TCP_CLOSING */ TCP_CLOSING
,
1429 static int tcp_close_state(struct sock
*sk
)
1431 int next
= (int)new_state
[sk
->sk_state
];
1432 int ns
= next
& TCP_STATE_MASK
;
1434 tcp_set_state(sk
, ns
);
1436 return next
& TCP_ACTION_FIN
;
1440 * Shutdown the sending side of a connection. Much like close except
1441 * that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
1444 void tcp_shutdown(struct sock
*sk
, int how
)
1446 /* We need to grab some memory, and put together a FIN,
1447 * and then put it into the queue to be sent.
1448 * Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1450 if (!(how
& SEND_SHUTDOWN
))
1453 /* If we've already sent a FIN, or it's a closed state, skip this. */
1454 if ((1 << sk
->sk_state
) &
1455 (TCPF_ESTABLISHED
| TCPF_SYN_SENT
|
1456 TCPF_SYN_RECV
| TCPF_CLOSE_WAIT
)) {
1457 /* Clear out any half completed packets. FIN if needed. */
1458 if (tcp_close_state(sk
))
1463 void tcp_close(struct sock
*sk
, long timeout
)
1465 struct sk_buff
*skb
;
1466 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 /* It is the last release_sock in its life. It will remove backlog. */
1547 /* Now socket is owned by kernel and we acquire BH lock
1548 to finish close. No need to check for user refs.
1552 BUG_TRAP(!sock_owned_by_user(sk
));
1557 /* This is a (useful) BSD violating of the RFC. There is a
1558 * problem with TCP as specified in that the other end could
1559 * keep a socket open forever with no application left this end.
1560 * We use a 3 minute timeout (about the same as BSD) then kill
1561 * our end. If they send after that then tough - BUT: long enough
1562 * that we won't make the old 4*rto = almost no time - whoops
1565 * Nope, it was not mistake. It is really desired behaviour
1566 * f.e. on http servers, when such sockets are useless, but
1567 * consume significant resources. Let's do it with special
1568 * linger2 option. --ANK
1571 if (sk
->sk_state
== TCP_FIN_WAIT2
) {
1572 struct tcp_sock
*tp
= tcp_sk(sk
);
1573 if (tp
->linger2
< 0) {
1574 tcp_set_state(sk
, TCP_CLOSE
);
1575 tcp_send_active_reset(sk
, GFP_ATOMIC
);
1576 NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER
);
1578 const int tmo
= tcp_fin_time(sk
);
1580 if (tmo
> TCP_TIMEWAIT_LEN
) {
1581 inet_csk_reset_keepalive_timer(sk
, tcp_fin_time(sk
));
1583 atomic_inc(sk
->sk_prot
->orphan_count
);
1584 tcp_time_wait(sk
, TCP_FIN_WAIT2
, tmo
);
1589 if (sk
->sk_state
!= TCP_CLOSE
) {
1590 sk_stream_mem_reclaim(sk
);
1591 if (atomic_read(sk
->sk_prot
->orphan_count
) > sysctl_tcp_max_orphans
||
1592 (sk
->sk_wmem_queued
> SOCK_MIN_SNDBUF
&&
1593 atomic_read(&tcp_memory_allocated
) > sysctl_tcp_mem
[2])) {
1594 if (net_ratelimit())
1595 printk(KERN_INFO
"TCP: too many of orphaned "
1597 tcp_set_state(sk
, TCP_CLOSE
);
1598 tcp_send_active_reset(sk
, GFP_ATOMIC
);
1599 NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY
);
1602 atomic_inc(sk
->sk_prot
->orphan_count
);
1604 if (sk
->sk_state
== TCP_CLOSE
)
1605 inet_csk_destroy_sock(sk
);
1606 /* Otherwise, socket is reprieved until protocol close. */
1614 /* These states need RST on ABORT according to RFC793 */
1616 static inline int tcp_need_reset(int state
)
1618 return (1 << state
) &
1619 (TCPF_ESTABLISHED
| TCPF_CLOSE_WAIT
| TCPF_FIN_WAIT1
|
1620 TCPF_FIN_WAIT2
| TCPF_SYN_RECV
);
1623 int tcp_disconnect(struct sock
*sk
, int flags
)
1625 struct inet_sock
*inet
= inet_sk(sk
);
1626 struct inet_connection_sock
*icsk
= inet_csk(sk
);
1627 struct tcp_sock
*tp
= tcp_sk(sk
);
1629 int old_state
= sk
->sk_state
;
1631 if (old_state
!= TCP_CLOSE
)
1632 tcp_set_state(sk
, TCP_CLOSE
);
1634 /* ABORT function of RFC793 */
1635 if (old_state
== TCP_LISTEN
) {
1636 inet_csk_listen_stop(sk
);
1637 } else if (tcp_need_reset(old_state
) ||
1638 (tp
->snd_nxt
!= tp
->write_seq
&&
1639 (1 << old_state
) & (TCPF_CLOSING
| TCPF_LAST_ACK
))) {
1640 /* The last check adjusts for discrepance of Linux wrt. RFC
1643 tcp_send_active_reset(sk
, gfp_any());
1644 sk
->sk_err
= ECONNRESET
;
1645 } else if (old_state
== TCP_SYN_SENT
)
1646 sk
->sk_err
= ECONNRESET
;
1648 tcp_clear_xmit_timers(sk
);
1649 __skb_queue_purge(&sk
->sk_receive_queue
);
1650 sk_stream_writequeue_purge(sk
);
1651 __skb_queue_purge(&tp
->out_of_order_queue
);
1655 if (!(sk
->sk_userlocks
& SOCK_BINDADDR_LOCK
))
1656 inet_reset_saddr(sk
);
1658 sk
->sk_shutdown
= 0;
1659 sock_reset_flag(sk
, SOCK_DONE
);
1661 if ((tp
->write_seq
+= tp
->max_window
+ 2) == 0)
1663 icsk
->icsk_backoff
= 0;
1665 icsk
->icsk_probes_out
= 0;
1666 tp
->packets_out
= 0;
1667 tp
->snd_ssthresh
= 0x7fffffff;
1668 tp
->snd_cwnd_cnt
= 0;
1669 tcp_set_ca_state(sk
, TCP_CA_Open
);
1670 tcp_clear_retrans(tp
);
1671 inet_csk_delack_init(sk
);
1672 sk
->sk_send_head
= NULL
;
1673 tp
->rx_opt
.saw_tstamp
= 0;
1674 tcp_sack_reset(&tp
->rx_opt
);
1677 BUG_TRAP(!inet
->num
|| icsk
->icsk_bind_hash
);
1679 sk
->sk_error_report(sk
);
1684 * Socket option code for TCP.
1686 int tcp_setsockopt(struct sock
*sk
, int level
, int optname
, char __user
*optval
,
1689 struct tcp_sock
*tp
= tcp_sk(sk
);
1690 struct inet_connection_sock
*icsk
= inet_csk(sk
);
1694 if (level
!= SOL_TCP
)
1695 return tp
->af_specific
->setsockopt(sk
, level
, optname
,
1698 /* This is a string value all the others are int's */
1699 if (optname
== TCP_CONGESTION
) {
1700 char name
[TCP_CA_NAME_MAX
];
1705 val
= strncpy_from_user(name
, optval
,
1706 min(TCP_CA_NAME_MAX
-1, optlen
));
1712 err
= tcp_set_congestion_control(sk
, name
);
1717 if (optlen
< sizeof(int))
1720 if (get_user(val
, (int __user
*)optval
))
1727 /* Values greater than interface MTU won't take effect. However
1728 * at the point when this call is done we typically don't yet
1729 * know which interface is going to be used */
1730 if (val
< 8 || val
> MAX_TCP_WINDOW
) {
1734 tp
->rx_opt
.user_mss
= val
;
1739 /* TCP_NODELAY is weaker than TCP_CORK, so that
1740 * this option on corked socket is remembered, but
1741 * it is not activated until cork is cleared.
1743 * However, when TCP_NODELAY is set we make
1744 * an explicit push, which overrides even TCP_CORK
1745 * for currently queued segments.
1747 tp
->nonagle
|= TCP_NAGLE_OFF
|TCP_NAGLE_PUSH
;
1748 tcp_push_pending_frames(sk
, tp
);
1750 tp
->nonagle
&= ~TCP_NAGLE_OFF
;
1755 /* When set indicates to always queue non-full frames.
1756 * Later the user clears this option and we transmit
1757 * any pending partial frames in the queue. This is
1758 * meant to be used alongside sendfile() to get properly
1759 * filled frames when the user (for example) must write
1760 * out headers with a write() call first and then use
1761 * sendfile to send out the data parts.
1763 * TCP_CORK can be set together with TCP_NODELAY and it is
1764 * stronger than TCP_NODELAY.
1767 tp
->nonagle
|= TCP_NAGLE_CORK
;
1769 tp
->nonagle
&= ~TCP_NAGLE_CORK
;
1770 if (tp
->nonagle
&TCP_NAGLE_OFF
)
1771 tp
->nonagle
|= TCP_NAGLE_PUSH
;
1772 tcp_push_pending_frames(sk
, tp
);
1777 if (val
< 1 || val
> MAX_TCP_KEEPIDLE
)
1780 tp
->keepalive_time
= val
* HZ
;
1781 if (sock_flag(sk
, SOCK_KEEPOPEN
) &&
1782 !((1 << sk
->sk_state
) &
1783 (TCPF_CLOSE
| TCPF_LISTEN
))) {
1784 __u32 elapsed
= tcp_time_stamp
- tp
->rcv_tstamp
;
1785 if (tp
->keepalive_time
> elapsed
)
1786 elapsed
= tp
->keepalive_time
- elapsed
;
1789 inet_csk_reset_keepalive_timer(sk
, elapsed
);
1794 if (val
< 1 || val
> MAX_TCP_KEEPINTVL
)
1797 tp
->keepalive_intvl
= val
* HZ
;
1800 if (val
< 1 || val
> MAX_TCP_KEEPCNT
)
1803 tp
->keepalive_probes
= val
;
1806 if (val
< 1 || val
> MAX_TCP_SYNCNT
)
1809 icsk
->icsk_syn_retries
= val
;
1815 else if (val
> sysctl_tcp_fin_timeout
/ HZ
)
1818 tp
->linger2
= val
* HZ
;
1821 case TCP_DEFER_ACCEPT
:
1822 icsk
->icsk_accept_queue
.rskq_defer_accept
= 0;
1824 /* Translate value in seconds to number of
1826 while (icsk
->icsk_accept_queue
.rskq_defer_accept
< 32 &&
1827 val
> ((TCP_TIMEOUT_INIT
/ HZ
) <<
1828 icsk
->icsk_accept_queue
.rskq_defer_accept
))
1829 icsk
->icsk_accept_queue
.rskq_defer_accept
++;
1830 icsk
->icsk_accept_queue
.rskq_defer_accept
++;
1834 case TCP_WINDOW_CLAMP
:
1836 if (sk
->sk_state
!= TCP_CLOSE
) {
1840 tp
->window_clamp
= 0;
1842 tp
->window_clamp
= val
< SOCK_MIN_RCVBUF
/ 2 ?
1843 SOCK_MIN_RCVBUF
/ 2 : val
;
1848 icsk
->icsk_ack
.pingpong
= 1;
1850 icsk
->icsk_ack
.pingpong
= 0;
1851 if ((1 << sk
->sk_state
) &
1852 (TCPF_ESTABLISHED
| TCPF_CLOSE_WAIT
) &&
1853 inet_csk_ack_scheduled(sk
)) {
1854 icsk
->icsk_ack
.pending
|= ICSK_ACK_PUSHED
;
1855 cleanup_rbuf(sk
, 1);
1857 icsk
->icsk_ack
.pingpong
= 1;
1870 /* Return information about state of tcp endpoint in API format. */
1871 void tcp_get_info(struct sock
*sk
, struct tcp_info
*info
)
1873 struct tcp_sock
*tp
= tcp_sk(sk
);
1874 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
1875 u32 now
= tcp_time_stamp
;
1877 memset(info
, 0, sizeof(*info
));
1879 info
->tcpi_state
= sk
->sk_state
;
1880 info
->tcpi_ca_state
= icsk
->icsk_ca_state
;
1881 info
->tcpi_retransmits
= icsk
->icsk_retransmits
;
1882 info
->tcpi_probes
= icsk
->icsk_probes_out
;
1883 info
->tcpi_backoff
= icsk
->icsk_backoff
;
1885 if (tp
->rx_opt
.tstamp_ok
)
1886 info
->tcpi_options
|= TCPI_OPT_TIMESTAMPS
;
1887 if (tp
->rx_opt
.sack_ok
)
1888 info
->tcpi_options
|= TCPI_OPT_SACK
;
1889 if (tp
->rx_opt
.wscale_ok
) {
1890 info
->tcpi_options
|= TCPI_OPT_WSCALE
;
1891 info
->tcpi_snd_wscale
= tp
->rx_opt
.snd_wscale
;
1892 info
->tcpi_rcv_wscale
= tp
->rx_opt
.rcv_wscale
;
1895 if (tp
->ecn_flags
&TCP_ECN_OK
)
1896 info
->tcpi_options
|= TCPI_OPT_ECN
;
1898 info
->tcpi_rto
= jiffies_to_usecs(icsk
->icsk_rto
);
1899 info
->tcpi_ato
= jiffies_to_usecs(icsk
->icsk_ack
.ato
);
1900 info
->tcpi_snd_mss
= tp
->mss_cache
;
1901 info
->tcpi_rcv_mss
= icsk
->icsk_ack
.rcv_mss
;
1903 info
->tcpi_unacked
= tp
->packets_out
;
1904 info
->tcpi_sacked
= tp
->sacked_out
;
1905 info
->tcpi_lost
= tp
->lost_out
;
1906 info
->tcpi_retrans
= tp
->retrans_out
;
1907 info
->tcpi_fackets
= tp
->fackets_out
;
1909 info
->tcpi_last_data_sent
= jiffies_to_msecs(now
- tp
->lsndtime
);
1910 info
->tcpi_last_data_recv
= jiffies_to_msecs(now
- icsk
->icsk_ack
.lrcvtime
);
1911 info
->tcpi_last_ack_recv
= jiffies_to_msecs(now
- tp
->rcv_tstamp
);
1913 info
->tcpi_pmtu
= tp
->pmtu_cookie
;
1914 info
->tcpi_rcv_ssthresh
= tp
->rcv_ssthresh
;
1915 info
->tcpi_rtt
= jiffies_to_usecs(tp
->srtt
)>>3;
1916 info
->tcpi_rttvar
= jiffies_to_usecs(tp
->mdev
)>>2;
1917 info
->tcpi_snd_ssthresh
= tp
->snd_ssthresh
;
1918 info
->tcpi_snd_cwnd
= tp
->snd_cwnd
;
1919 info
->tcpi_advmss
= tp
->advmss
;
1920 info
->tcpi_reordering
= tp
->reordering
;
1922 info
->tcpi_rcv_rtt
= jiffies_to_usecs(tp
->rcv_rtt_est
.rtt
)>>3;
1923 info
->tcpi_rcv_space
= tp
->rcvq_space
.space
;
1925 info
->tcpi_total_retrans
= tp
->total_retrans
;
1928 EXPORT_SYMBOL_GPL(tcp_get_info
);
1930 int tcp_getsockopt(struct sock
*sk
, int level
, int optname
, char __user
*optval
,
1933 struct inet_connection_sock
*icsk
= inet_csk(sk
);
1934 struct tcp_sock
*tp
= tcp_sk(sk
);
1937 if (level
!= SOL_TCP
)
1938 return tp
->af_specific
->getsockopt(sk
, level
, optname
,
1941 if (get_user(len
, optlen
))
1944 len
= min_t(unsigned int, len
, sizeof(int));
1951 val
= tp
->mss_cache
;
1952 if (!val
&& ((1 << sk
->sk_state
) & (TCPF_CLOSE
| TCPF_LISTEN
)))
1953 val
= tp
->rx_opt
.user_mss
;
1956 val
= !!(tp
->nonagle
&TCP_NAGLE_OFF
);
1959 val
= !!(tp
->nonagle
&TCP_NAGLE_CORK
);
1962 val
= (tp
->keepalive_time
? : sysctl_tcp_keepalive_time
) / HZ
;
1965 val
= (tp
->keepalive_intvl
? : sysctl_tcp_keepalive_intvl
) / HZ
;
1968 val
= tp
->keepalive_probes
? : sysctl_tcp_keepalive_probes
;
1971 val
= icsk
->icsk_syn_retries
? : sysctl_tcp_syn_retries
;
1976 val
= (val
? : sysctl_tcp_fin_timeout
) / HZ
;
1978 case TCP_DEFER_ACCEPT
:
1979 val
= !icsk
->icsk_accept_queue
.rskq_defer_accept
? 0 :
1980 ((TCP_TIMEOUT_INIT
/ HZ
) << (icsk
->icsk_accept_queue
.rskq_defer_accept
- 1));
1982 case TCP_WINDOW_CLAMP
:
1983 val
= tp
->window_clamp
;
1986 struct tcp_info info
;
1988 if (get_user(len
, optlen
))
1991 tcp_get_info(sk
, &info
);
1993 len
= min_t(unsigned int, len
, sizeof(info
));
1994 if (put_user(len
, optlen
))
1996 if (copy_to_user(optval
, &info
, len
))
2001 val
= !icsk
->icsk_ack
.pingpong
;
2004 case TCP_CONGESTION
:
2005 if (get_user(len
, optlen
))
2007 len
= min_t(unsigned int, len
, TCP_CA_NAME_MAX
);
2008 if (put_user(len
, optlen
))
2010 if (copy_to_user(optval
, icsk
->icsk_ca_ops
->name
, len
))
2014 return -ENOPROTOOPT
;
2017 if (put_user(len
, optlen
))
2019 if (copy_to_user(optval
, &val
, len
))
2025 extern void __skb_cb_too_small_for_tcp(int, int);
2026 extern struct tcp_congestion_ops tcp_reno
;
2028 static __initdata
unsigned long thash_entries
;
2029 static int __init
set_thash_entries(char *str
)
2033 thash_entries
= simple_strtoul(str
, &str
, 0);
2036 __setup("thash_entries=", set_thash_entries
);
2038 void __init
tcp_init(void)
2040 struct sk_buff
*skb
= NULL
;
2043 if (sizeof(struct tcp_skb_cb
) > sizeof(skb
->cb
))
2044 __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb
),
2047 tcp_hashinfo
.bind_bucket_cachep
=
2048 kmem_cache_create("tcp_bind_bucket",
2049 sizeof(struct inet_bind_bucket
), 0,
2050 SLAB_HWCACHE_ALIGN
, NULL
, NULL
);
2051 if (!tcp_hashinfo
.bind_bucket_cachep
)
2052 panic("tcp_init: Cannot alloc tcp_bind_bucket cache.");
2054 /* Size and allocate the main established and bind bucket
2057 * The methodology is similar to that of the buffer cache.
2059 tcp_hashinfo
.ehash
=
2060 alloc_large_system_hash("TCP established",
2061 sizeof(struct inet_ehash_bucket
),
2063 (num_physpages
>= 128 * 1024) ?
2067 &tcp_hashinfo
.ehash_size
,
2070 tcp_hashinfo
.ehash_size
= (1 << tcp_hashinfo
.ehash_size
) >> 1;
2071 for (i
= 0; i
< (tcp_hashinfo
.ehash_size
<< 1); i
++) {
2072 rwlock_init(&tcp_hashinfo
.ehash
[i
].lock
);
2073 INIT_HLIST_HEAD(&tcp_hashinfo
.ehash
[i
].chain
);
2076 tcp_hashinfo
.bhash
=
2077 alloc_large_system_hash("TCP bind",
2078 sizeof(struct inet_bind_hashbucket
),
2079 tcp_hashinfo
.ehash_size
,
2080 (num_physpages
>= 128 * 1024) ?
2084 &tcp_hashinfo
.bhash_size
,
2087 tcp_hashinfo
.bhash_size
= 1 << tcp_hashinfo
.bhash_size
;
2088 for (i
= 0; i
< tcp_hashinfo
.bhash_size
; i
++) {
2089 spin_lock_init(&tcp_hashinfo
.bhash
[i
].lock
);
2090 INIT_HLIST_HEAD(&tcp_hashinfo
.bhash
[i
].chain
);
2093 /* Try to be a bit smarter and adjust defaults depending
2094 * on available memory.
2096 for (order
= 0; ((1 << order
) << PAGE_SHIFT
) <
2097 (tcp_hashinfo
.bhash_size
* sizeof(struct inet_bind_hashbucket
));
2101 sysctl_local_port_range
[0] = 32768;
2102 sysctl_local_port_range
[1] = 61000;
2103 tcp_death_row
.sysctl_max_tw_buckets
= 180000;
2104 sysctl_tcp_max_orphans
= 4096 << (order
- 4);
2105 sysctl_max_syn_backlog
= 1024;
2106 } else if (order
< 3) {
2107 sysctl_local_port_range
[0] = 1024 * (3 - order
);
2108 tcp_death_row
.sysctl_max_tw_buckets
>>= (3 - order
);
2109 sysctl_tcp_max_orphans
>>= (3 - order
);
2110 sysctl_max_syn_backlog
= 128;
2112 tcp_hashinfo
.port_rover
= sysctl_local_port_range
[0] - 1;
2114 sysctl_tcp_mem
[0] = 768 << order
;
2115 sysctl_tcp_mem
[1] = 1024 << order
;
2116 sysctl_tcp_mem
[2] = 1536 << order
;
2119 sysctl_tcp_wmem
[2] = 64 * 1024;
2120 sysctl_tcp_rmem
[0] = PAGE_SIZE
;
2121 sysctl_tcp_rmem
[1] = 43689;
2122 sysctl_tcp_rmem
[2] = 2 * 43689;
2125 printk(KERN_INFO
"TCP: Hash tables configured "
2126 "(established %d bind %d)\n",
2127 tcp_hashinfo
.ehash_size
<< 1, tcp_hashinfo
.bhash_size
);
2129 tcp_register_congestion_control(&tcp_reno
);
2132 EXPORT_SYMBOL(tcp_close
);
2133 EXPORT_SYMBOL(tcp_disconnect
);
2134 EXPORT_SYMBOL(tcp_getsockopt
);
2135 EXPORT_SYMBOL(tcp_ioctl
);
2136 EXPORT_SYMBOL(tcp_poll
);
2137 EXPORT_SYMBOL(tcp_read_sock
);
2138 EXPORT_SYMBOL(tcp_recvmsg
);
2139 EXPORT_SYMBOL(tcp_sendmsg
);
2140 EXPORT_SYMBOL(tcp_sendpage
);
2141 EXPORT_SYMBOL(tcp_setsockopt
);
2142 EXPORT_SYMBOL(tcp_shutdown
);
2143 EXPORT_SYMBOL(tcp_statistics
);