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*/
1 /*
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.
5 *
6 * Implementation of the Transmission Control Protocol(TCP).
7 *
8 * Version: @(#)tcp.c 1.0.16 05/25/93
9 *
10 * Authors: Ross Biro, <bir7@leland.Stanford.Edu>
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>
21 *
22 * Fixes:
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
27 * (tcp_err()).
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. select
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
38 * unknown sockets.
39 * Alan Cox : tcp option processing.
40 * Alan Cox : Reset tweaked (still not 100%) [Had
41 * syn rule wrong]
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
47 * escape still
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
51 * facilities
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
56 * bit to skb ops.
57 * Alan Cox : Tidied tcp_data to avoid a potential
58 * nasty.
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
70 * sockets.
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
74 * state ack error.
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
79 * fixes
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
85 * completely
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
93 * (not yet usable)
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 select() after URG properly in
106 * all cases.
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(), select() after URG
111 * works now.
112 * Michael Pall : recv(...,MSG_OOB) never blocks in the
113 * BSD api.
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
121 * fixed ports.
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
127 * socket close.
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 selecting before an
132 * accept.
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
143 * close.
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
149 * comments.
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
157 * resemble the RFC.
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
162 * generates them.
163 * Alan Cox : Cache last socket.
164 * Alan Cox : Per route irtt.
165 * Matt Day : 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 stat is TCP_CLOSED.
173 * Alan Cox : Look up device on a retransmit - routes may
174 * change. Doesn't yet cope with MSS shrink right
175 * but its a start!
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 pathalogical 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 *
192 * To Fix:
193 * Fast path the code. Two things here - fix the window calculation
194 * so it doesn't iterate over the queue, also spot packets with no funny
195 * options arriving in order and process directly.
196 *
197 * Rewrite output state machine to use a single queue.
198 * Speed up input assembly algorithm.
199 * RFC1323 - PAWS and window scaling. PAWS is required for IPv6 so we
200 * could do with it working on IPv4
201 * User settable/learned rtt/max window/mtu
202 *
203 * Change the fundamental structure to a single send queue maintained
204 * by TCP (removing the bogus ip stuff [thus fixing mtu drops on
205 * active routes too]). Cut the queue off in tcp_retransmit/
206 * tcp_transmit.
207 * Change the receive queue to assemble as it goes. This lets us
208 * dispose of most of tcp_sequence, half of tcp_ack and chunks of
209 * tcp_data/tcp_read as well as the window shrink crud.
210 * Separate out duplicated code - tcp_alloc_skb, tcp_build_ack
211 * tcp_queue_skb seem obvious routines to extract.
212 *
213 * This program is free software; you can redistribute it and/or
214 * modify it under the terms of the GNU General Public License
215 * as published by the Free Software Foundation; either version
216 * 2 of the License, or(at your option) any later version.
217 *
218 * Description of States:
219 *
220 * TCP_SYN_SENT sent a connection request, waiting for ack
221 *
222 * TCP_SYN_RECV received a connection request, sent ack,
223 * waiting for final ack in three-way handshake.
224 *
225 * TCP_ESTABLISHED connection established
226 *
227 * TCP_FIN_WAIT1 our side has shutdown, waiting to complete
228 * transmission of remaining buffered data
229 *
230 * TCP_FIN_WAIT2 all buffered data sent, waiting for remote
231 * to shutdown
232 *
233 * TCP_CLOSING both sides have shutdown but we still have
234 * data we have to finish sending
235 *
236 * TCP_TIME_WAIT timeout to catch resent junk before entering
237 * closed, can only be entered from FIN_WAIT2
238 * or CLOSING. Required because the other end
239 * may not have gotten our last ACK causing it
240 * to retransmit the data packet (which we ignore)
241 *
242 * TCP_CLOSE_WAIT remote side has shutdown and is waiting for
243 * us to finish writing our data and to shutdown
244 * (we have to close() to move on to LAST_ACK)
245 *
246 * TCP_LAST_ACK out side has shutdown after remote has
247 * shutdown. There may still be data in our
248 * buffer that we have to finish sending
249 *
250 * TCP_CLOSE socket is finished
251 */
252
253 /*
254 * RFC1122 status:
255 * NOTE: I'm not going to be doing comments in the code for this one except
256 * for violations and the like. tcp.c is just too big... If I say something
257 * "does?" or "doesn't?", it means I'm not sure, and will have to hash it out
258 * with Alan. -- MS 950903
259 *
260 * Use of PSH (4.2.2.2)
261 * MAY aggregate data sent without the PSH flag. (does)
262 * MAY queue data received without the PSH flag. (does)
263 * SHOULD collapse successive PSH flags when it packetizes data. (doesn't)
264 * MAY implement PSH on send calls. (doesn't, thus:)
265 * MUST NOT buffer data indefinitely (doesn't [1 second])
266 * MUST set PSH on last segment (does)
267 * MAY pass received PSH to application layer (doesn't)
268 * SHOULD send maximum-sized segment whenever possible. (almost always does)
269 *
270 * Window Size (4.2.2.3, 4.2.2.16)
271 * MUST treat window size as an unsigned number (does)
272 * SHOULD treat window size as a 32-bit number (does not)
273 * MUST NOT shrink window once it is offered (does not normally)
274 *
275 * Urgent Pointer (4.2.2.4)
276 * **MUST point urgent pointer to last byte of urgent data (not right
277 * after). (doesn't, to be like BSD)
278 * MUST inform application layer asynchronously of incoming urgent
279 * data. (does)
280 * MUST provide application with means of determining the amount of
281 * urgent data pending. (does)
282 * **MUST support urgent data sequence of arbitrary length. (doesn't, but
283 * it's sort of tricky to fix, as urg_ptr is a 16-bit quantity)
284 * [Follows BSD 1 byte of urgent data]
285 *
286 * TCP Options (4.2.2.5)
287 * MUST be able to receive TCP options in any segment. (does)
288 * MUST ignore unsupported options (does)
289 *
290 * Maximum Segment Size Option (4.2.2.6)
291 * MUST implement both sending and receiving MSS. (does)
292 * SHOULD send an MSS with every SYN where receive MSS != 536 (MAY send
293 * it always). (does, even when MSS == 536, which is legal)
294 * MUST assume MSS == 536 if no MSS received at connection setup (does)
295 * MUST calculate "effective send MSS" correctly:
296 * min(physical_MTU, remote_MSS+20) - sizeof(tcphdr) - sizeof(ipopts)
297 * (does - but allows operator override)
298 *
299 * TCP Checksum (4.2.2.7)
300 * MUST generate and check TCP checksum. (does)
301 *
302 * Initial Sequence Number Selection (4.2.2.8)
303 * MUST use the RFC 793 clock selection mechanism. (doesn't, but it's
304 * OK: RFC 793 specifies a 250KHz clock, while we use 1MHz, which is
305 * necessary for 10Mbps networks - and harder than BSD to spoof!)
306 *
307 * Simultaneous Open Attempts (4.2.2.10)
308 * MUST support simultaneous open attempts (does)
309 *
310 * Recovery from Old Duplicate SYN (4.2.2.11)
311 * MUST keep track of active vs. passive open (does)
312 *
313 * RST segment (4.2.2.12)
314 * SHOULD allow an RST segment to contain data (does, but doesn't do
315 * anything with it, which is standard)
316 *
317 * Closing a Connection (4.2.2.13)
318 * MUST inform application of whether connectin was closed by RST or
319 * normal close. (does)
320 * MAY allow "half-duplex" close (treat connection as closed for the
321 * local app, even before handshake is done). (does)
322 * MUST linger in TIME_WAIT for 2 * MSL (does)
323 *
324 * Retransmission Timeout (4.2.2.15)
325 * MUST implement Jacobson's slow start and congestion avoidance
326 * stuff. (does)
327 *
328 * Probing Zero Windows (4.2.2.17)
329 * MUST support probing of zero windows. (does)
330 * MAY keep offered window closed indefinitely. (does)
331 * MUST allow remote window to stay closed indefinitely. (does)
332 *
333 * Passive Open Calls (4.2.2.18)
334 * MUST NOT let new passive open affect other connections. (doesn't)
335 * MUST support passive opens (LISTENs) concurrently. (does)
336 *
337 * Time to Live (4.2.2.19)
338 * MUST make TCP TTL configurable. (does - IP_TTL option)
339 *
340 * Event Processing (4.2.2.20)
341 * SHOULD queue out-of-order segments. (does)
342 * MUST aggregate ACK segments whenever possible. (does but badly)
343 *
344 * Retransmission Timeout Calculation (4.2.3.1)
345 * MUST implement Karn's algorithm and Jacobson's algorithm for RTO
346 * calculation. (does, or at least explains them in the comments 8*b)
347 * SHOULD initialize RTO to 0 and RTT to 3. (does)
348 *
349 * When to Send an ACK Segment (4.2.3.2)
350 * SHOULD implement delayed ACK. (does)
351 * MUST keep ACK delay < 0.5 sec. (does)
352 *
353 * When to Send a Window Update (4.2.3.3)
354 * MUST implement receiver-side SWS. (does)
355 *
356 * When to Send Data (4.2.3.4)
357 * MUST implement sender-side SWS. (does)
358 * SHOULD implement Nagle algorithm. (does)
359 *
360 * TCP Connection Failures (4.2.3.5)
361 * MUST handle excessive retransmissions "properly" (see the RFC). (does)
362 * SHOULD inform application layer of soft errors. (does)
363 *
364 * TCP Keep-Alives (4.2.3.6)
365 * MAY provide keep-alives. (does)
366 * MUST make keep-alives configurable on a per-connection basis. (does)
367 * MUST default to no keep-alives. (does)
368 * **MUST make keep-alive interval configurable. (doesn't)
369 * **MUST make default keep-alive interval > 2 hours. (doesn't)
370 * MUST NOT interpret failure to ACK keep-alive packet as dead
371 * connection. (doesn't)
372 * SHOULD send keep-alive with no data. (does)
373 *
374 * TCP Multihoming (4.2.3.7)
375 * MUST get source address from IP layer before sending first
376 * SYN. (does)
377 * MUST use same local address for all segments of a connection. (does)
378 *
379 * IP Options (4.2.3.8)
380 * MUST ignore unsupported IP options. (does)
381 * MAY support Time Stamp and Record Route. (does)
382 * MUST allow application to specify a source route. (does)
383 * MUST allow receieved Source Route option to set route for all future
384 * segments on this connection. (does not (security issues))
385 *
386 * ICMP messages (4.2.3.9)
387 * MUST act on ICMP errors. (does)
388 * MUST slow transmission upon receipt of a Source Quench. (does)
389 * MUST NOT abort connection upon receipt of soft Destination
390 * Unreachables (0, 1, 5), Time Exceededs and Parameter
391 * Problems. (doesn't)
392 * SHOULD report soft Destination Unreachables etc. to the
393 * application. (does)
394 * SHOULD abort connection upon receipt of hard Destination Unreachable
395 * messages (2, 3, 4). (does)
396 *
397 * Remote Address Validation (4.2.3.10)
398 * MUST reject as an error OPEN for invalid remote IP address. (does)
399 * MUST ignore SYN with invalid source address. (does)
400 * MUST silently discard incoming SYN for broadcast/multicast
401 * address. (does)
402 *
403 * Asynchronous Reports (4.2.4.1)
404 * MUST provide mechanism for reporting soft errors to application
405 * layer. (does)
406 *
407 * Type of Service (4.2.4.2)
408 * MUST allow application layer to set Type of Service. (does IP_TOS)
409 *
410 * (Whew. -- MS 950903)
411 **/
412
413 #include <linux/config.h>
414 #include <linux/types.h>
415 #include <linux/fcntl.h>
416
417 #include <net/icmp.h>
418 #include <net/tcp.h>
419
420 #include <asm/segment.h>
421
422 unsigned long seq_offset;
423 struct tcp_mib tcp_statistics;
424
425 static void tcp_close(struct sock *sk, unsigned long timeout);
426
427 /*
428 * The less said about this the better, but it works and will do for 1.2 (and 1.4 ;))
429 */
430
431 struct wait_queue *master_select_wakeup;
432
433 /*
434 * Find someone to 'accept'. Must be called with
435 * the socket locked or with interrupts disabled
436 */
437
438 static struct sk_buff *tcp_find_established(struct sock *s)
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*/
439 {
440 struct sk_buff *p=skb_peek(&s->receive_queue);
441 if(p==NULL)
442 return NULL;
443 do
444 {
445 if(p->sk->state == TCP_ESTABLISHED || p->sk->state >= TCP_FIN_WAIT1)
446 return p;
447 p=p->next;
448 }
449 while(p!=(struct sk_buff *)&s->receive_queue);
450 return NULL;
451 }
452
453 /*
454 * Remove a completed connection and return it. This is used by
455 * tcp_accept() to get connections from the queue.
456 */
457
458 static struct sk_buff *tcp_dequeue_established(struct sock *s)
/* ![[previous]](../icons/left.png)
*/
459 {
460 struct sk_buff *skb;
461 unsigned long flags;
462 save_flags(flags);
463 cli();
464 skb=tcp_find_established(s);
465 if(skb!=NULL)
466 skb_unlink(skb); /* Take it off the queue */
467 restore_flags(flags);
468 return skb;
469 }
470
471 /*
472 * This routine closes sockets which have been at least partially
473 * opened, but not yet accepted. Currently it is only called by
474 * tcp_close, and timeout mirrors the value there.
475 */
476
477 static void tcp_close_pending (struct sock *sk)
/* */
478 {
479 struct sk_buff *skb;
480
481 while ((skb = skb_dequeue(&sk->receive_queue)) != NULL)
482 {
483 skb->sk->dead=1;
484 tcp_close(skb->sk, 0);
485 kfree_skb(skb, FREE_READ);
486 }
487 return;
488 }
489
490 /*
491 * Enter the time wait state.
492 */
493
494 void tcp_time_wait(struct sock *sk)
/* */
495 {
496 tcp_set_state(sk,TCP_TIME_WAIT);
497 sk->shutdown = SHUTDOWN_MASK;
498 if (!sk->dead)
499 sk->state_change(sk);
500 tcp_reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
501 }
502
503
504 /*
505 * This routine is called by the ICMP module when it gets some
506 * sort of error condition. If err < 0 then the socket should
507 * be closed and the error returned to the user. If err > 0
508 * it's just the icmp type << 8 | icmp code. After adjustment
509 * header points to the first 8 bytes of the tcp header. We need
510 * to find the appropriate port.
511 */
512
513 void tcp_err(int type, int code, unsigned char *header, __u32 daddr,
/* */
514 __u32 saddr, struct inet_protocol *protocol)
515 {
516 struct tcphdr *th = (struct tcphdr *)header;
517 struct sock *sk;
518
519 /*
520 * This one is _WRONG_. FIXME urgently.
521 */
522 #ifndef CONFIG_NO_PATH_MTU_DISCOVERY
523 struct iphdr *iph=(struct iphdr *)(header-sizeof(struct iphdr));
524 #endif
525 th =(struct tcphdr *)header;
526 sk = get_sock(&tcp_prot, th->source, daddr, th->dest, saddr);
527
528 if (sk == NULL)
529 return;
530
531 if (type == ICMP_SOURCE_QUENCH)
532 {
533 /*
534 * FIXME:
535 * For now we will just trigger a linear backoff.
536 * The slow start code should cause a real backoff here.
537 */
538 if (sk->cong_window > 4)
539 sk->cong_window--;
540 return;
541 }
542
543 if (type == ICMP_PARAMETERPROB)
544 {
545 sk->err=EPROTO;
546 sk->error_report(sk);
547 }
548
549 #ifndef CONFIG_NO_PATH_MTU_DISCOVERY
550 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
551 {
552 struct rtable * rt;
553 /*
554 * Ugly trick to pass MTU to protocol layer.
555 * Really we should add argument "info" to error handler.
556 */
557 unsigned short new_mtu = ntohs(iph->id);
558
559 if ((rt = sk->ip_route_cache) != NULL)
560 if (rt->rt_mtu > new_mtu)
561 rt->rt_mtu = new_mtu;
562
563 if (sk->mtu > new_mtu - sizeof(struct iphdr) - sizeof(struct tcphdr)
564 && new_mtu > sizeof(struct iphdr)+sizeof(struct tcphdr))
565 sk->mtu = new_mtu - sizeof(struct iphdr) - sizeof(struct tcphdr);
566
567 return;
568 }
569 #endif
570
571 /*
572 * If we've already connected we will keep trying
573 * until we time out, or the user gives up.
574 */
575
576 if (code < 13)
577 {
578 if(icmp_err_convert[code].fatal || sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
579 {
580 sk->err = icmp_err_convert[code].errno;
581 if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
582 {
583 tcp_statistics.TcpAttemptFails++;
584 tcp_set_state(sk,TCP_CLOSE);
585 sk->error_report(sk); /* Wake people up to see the error (see connect in sock.c) */
586 }
587 }
588 else /* Only an error on timeout */
589 sk->err_soft = icmp_err_convert[code].errno;
590 }
591 }
592
593
594 /*
595 * Walk down the receive queue counting readable data until we hit the end or we find a gap
596 * in the received data queue (ie a frame missing that needs sending to us). Not
597 * sorting using two queues as data arrives makes life so much harder.
598 */
599
600 static int tcp_readable(struct sock *sk)
/* */
601 {
602 unsigned long counted;
603 unsigned long amount;
604 struct sk_buff *skb;
605 int sum;
606 unsigned long flags;
607
608 if(sk && sk->debug)
609 printk("tcp_readable: %p - ",sk);
610
611 save_flags(flags);
612 cli();
613 if (sk == NULL || (skb = skb_peek(&sk->receive_queue)) == NULL)
614 {
615 restore_flags(flags);
616 if(sk && sk->debug)
617 printk("empty\n");
618 return(0);
619 }
620
621 counted = sk->copied_seq; /* Where we are at the moment */
622 amount = 0;
623
624 /*
625 * Do until a push or until we are out of data.
626 */
627
628 do
629 {
630 if (before(counted, skb->seq)) /* Found a hole so stops here */
631 break;
632 sum = skb->len - (counted - skb->seq); /* Length - header but start from where we are up to (avoid overlaps) */
633 if (skb->h.th->syn)
634 sum++;
635 if (sum > 0)
636 { /* Add it up, move on */
637 amount += sum;
638 if (skb->h.th->syn)
639 amount--;
640 counted += sum;
641 }
642 /*
643 * Don't count urg data ... but do it in the right place!
644 * Consider: "old_data (ptr is here) URG PUSH data"
645 * The old code would stop at the first push because
646 * it counted the urg (amount==1) and then does amount--
647 * *after* the loop. This means tcp_readable() always
648 * returned zero if any URG PUSH was in the queue, even
649 * though there was normal data available. If we subtract
650 * the urg data right here, we even get it to work for more
651 * than one URG PUSH skb without normal data.
652 * This means that select() finally works now with urg data
653 * in the queue. Note that rlogin was never affected
654 * because it doesn't use select(); it uses two processes
655 * and a blocking read(). And the queue scan in tcp_read()
656 * was correct. Mike <pall@rz.uni-karlsruhe.de>
657 */
658 if (skb->h.th->urg)
659 amount--; /* don't count urg data */
660 if (amount && skb->h.th->psh) break;
661 skb = skb->next;
662 }
663 while(skb != (struct sk_buff *)&sk->receive_queue);
664
665 restore_flags(flags);
666 if(sk->debug)
667 printk("got %lu bytes.\n",amount);
668 return(amount);
669 }
670
671 /*
672 * LISTEN is a special case for select..
673 */
674 static int tcp_listen_select(struct sock *sk, int sel_type, select_table *wait)
/* */
675 {
676 if (sel_type == SEL_IN) {
677 int retval;
678
679 lock_sock(sk);
680 retval = (tcp_find_established(sk) != NULL);
681 release_sock(sk);
682 if (!retval)
683 select_wait(&master_select_wakeup,wait);
684 return retval;
685 }
686 return 0;
687 }
688
689
690 /*
691 * Wait for a TCP event.
692 *
693 * Note that we don't need to lock the socket, as the upper select layers
694 * take care of normal races (between the test and the event) and we don't
695 * go look at any of the socket buffers directly.
696 */
697 static int tcp_select(struct sock *sk, int sel_type, select_table *wait)
/* */
698 {
699 if (sk->state == TCP_LISTEN)
700 return tcp_listen_select(sk, sel_type, wait);
701
702 switch(sel_type) {
703 case SEL_IN:
704 if (sk->err)
705 return 1;
706 if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
707 break;
708
709 if (sk->shutdown & RCV_SHUTDOWN)
710 return 1;
711
712 if (sk->acked_seq == sk->copied_seq)
713 break;
714
715 if (sk->urg_seq != sk->copied_seq ||
716 sk->acked_seq != sk->copied_seq+1 ||
717 sk->urginline || !sk->urg_data)
718 return 1;
719 break;
720
721 case SEL_OUT:
722 if (sk->err)
723 return 1;
724 if (sk->shutdown & SEND_SHUTDOWN)
725 return 0;
726 if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
727 break;
728 /*
729 * This is now right thanks to a small fix
730 * by Matt Dillon.
731 */
732
733 if (sock_wspace(sk) < sk->mtu+128+sk->prot->max_header)
734 break;
735 return 1;
736
737 case SEL_EX:
738 if (sk->urg_data)
739 return 1;
740 break;
741 }
742 select_wait(sk->sleep, wait);
743 return 0;
744 }
745
746 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
/* */
747 {
748 int err;
749 switch(cmd)
750 {
751
752 case TIOCINQ:
753 #ifdef FIXME /* FIXME: */
754 case FIONREAD:
755 #endif
756 {
757 unsigned long amount;
758
759 if (sk->state == TCP_LISTEN)
760 return(-EINVAL);
761
762 lock_sock(sk);
763 amount = tcp_readable(sk);
764 release_sock(sk);
765 err=verify_area(VERIFY_WRITE,(void *)arg, sizeof(int));
766 if(err)
767 return err;
768 put_user(amount, (int *)arg);
769 return(0);
770 }
771 case SIOCATMARK:
772 {
773 int answ = sk->urg_data && sk->urg_seq == sk->copied_seq;
774
775 err = verify_area(VERIFY_WRITE,(void *) arg, sizeof(int));
776 if (err)
777 return err;
778 put_user(answ,(int *) arg);
779 return(0);
780 }
781 case TIOCOUTQ:
782 {
783 unsigned long amount;
784
785 if (sk->state == TCP_LISTEN) return(-EINVAL);
786 amount = sock_wspace(sk);
787 err=verify_area(VERIFY_WRITE,(void *)arg, sizeof(int));
788 if(err)
789 return err;
790 put_user(amount, (int *)arg);
791 return(0);
792 }
793 default:
794 return(-EINVAL);
795 }
796 }
797
798
799 /*
800 * This routine computes a TCP checksum.
801 *
802 * Modified January 1995 from a go-faster DOS routine by
803 * Jorge Cwik <jorge@laser.satlink.net>
804 */
805 #undef DEBUG_TCP_CHECK
806 void tcp_send_check(struct tcphdr *th, unsigned long saddr,
/* */
807 unsigned long daddr, int len, struct sk_buff *skb)
808 {
809 #ifdef DEBUG_TCP_CHECK
810 u16 check;
811 #endif
812 th->check = 0;
813 th->check = tcp_check(th, len, saddr, daddr,
814 csum_partial((char *)th,sizeof(*th),skb->csum));
815
816 #ifdef DEBUG_TCP_CHECK
817 check = th->check;
818 th->check = 0;
819 th->check = tcp_check(th, len, saddr, daddr,
820 csum_partial((char *)th,len,0));
821 if (check != th->check) {
822 static int count = 0;
823 if (++count < 10) {
824 printk("Checksum %x (%x) from %p\n", th->check, check,
825 (&th)[-1]);
826 printk("TCP=<off:%d a:%d s:%d f:%d>\n", th->doff*4, th->ack, th->syn, th->fin);
827 }
828 }
829 #endif
830 }
831
832
833 /*
834 * This routine builds a generic TCP header.
835 */
836
837 extern __inline int tcp_build_header(struct tcphdr *th, struct sock *sk, int push)
/* */
838 {
839
840 memcpy(th,(void *) &(sk->dummy_th), sizeof(*th));
841 th->seq = htonl(sk->write_seq);
842 th->psh =(push == 0) ? 1 : 0;
843 sk->ack_backlog = 0;
844 sk->bytes_rcv = 0;
845 sk->ack_timed = 0;
846 th->ack_seq = htonl(sk->acked_seq);
847 sk->window = tcp_select_window(sk);
848 th->window = htons(sk->window);
849
850 return(sizeof(*th));
851 }
852
853 /*
854 * Wait for a socket to get into the connected state
855 */
856 static void wait_for_tcp_connect(struct sock * sk)
/* */
857 {
858 release_sock(sk);
859 cli();
860 if (sk->state != TCP_ESTABLISHED && sk->state != TCP_CLOSE_WAIT && sk->err == 0)
861 {
862 interruptible_sleep_on(sk->sleep);
863 }
864 sti();
865 lock_sock(sk);
866 }
867
868 /*
869 * Wait for more memory for a socket
870 */
871 static void wait_for_tcp_memory(struct sock * sk)
/* */
872 {
873 release_sock(sk);
874 cli();
875 if (sk->wmem_alloc*2 > sk->sndbuf &&
876 (sk->state == TCP_ESTABLISHED||sk->state == TCP_CLOSE_WAIT)
877 && sk->err == 0)
878 {
879 sk->socket->flags &= ~SO_NOSPACE;
880 interruptible_sleep_on(sk->sleep);
881 }
882 sti();
883 lock_sock(sk);
884 }
885
886
887 /*
888 * This routine copies from a user buffer into a socket,
889 * and starts the transmit system.
890 */
891
892 static int do_tcp_sendmsg(struct sock *sk, struct msghdr *msg,
/* */
893 int len, int nonblock, int flags)
894 {
895 int copied = 0;
896 int copy;
897 int tmp;
898 int seglen;
899 int iovct=0;
900 struct sk_buff *skb;
901 struct sk_buff *send_tmp;
902 struct proto *prot;
903 struct device *dev = NULL;
904 unsigned char *from;
905
906 /*
907 * Ok commence sending
908 */
909
910 while(iovct<msg->msg_iovlen)
911 {
912 seglen=msg->msg_iov[iovct].iov_len;
913 from=msg->msg_iov[iovct++].iov_base;
914 prot = sk->prot;
915 while(seglen > 0)
916 {
917 /*
918 * Stop on errors
919 */
920 if (sk->err)
921 {
922 if (copied)
923 return copied;
924 return sock_error(sk);
925 }
926
927 /*
928 * Make sure that we are established.
929 */
930 if (sk->shutdown & SEND_SHUTDOWN)
931 {
932 if (copied)
933 return copied;
934 return -EPIPE;
935 }
936
937 /*
938 * Wait for a connection to finish.
939 */
940 while (sk->state != TCP_ESTABLISHED && sk->state != TCP_CLOSE_WAIT)
941 {
942 if (copied)
943 return copied;
944
945 if (sk->err)
946 return sock_error(sk);
947
948 if (sk->state != TCP_SYN_SENT && sk->state != TCP_SYN_RECV)
949 {
950 if (sk->keepopen)
951 send_sig(SIGPIPE, current, 0);
952 return -EPIPE;
953 }
954
955 if (nonblock)
956 return -EAGAIN;
957
958 if (current->signal & ~current->blocked)
959 return -ERESTARTSYS;
960
961 wait_for_tcp_connect(sk);
962 }
963
964 /*
965 * The following code can result in copy <= if sk->mss is ever
966 * decreased. It shouldn't be. sk->mss is min(sk->mtu, sk->max_window).
967 * sk->mtu is constant once SYN processing is finished. I.e. we
968 * had better not get here until we've seen his SYN and at least one
969 * valid ack. (The SYN sets sk->mtu and the ack sets sk->max_window.)
970 * But ESTABLISHED should guarantee that. sk->max_window is by definition
971 * non-decreasing. Note that any ioctl to set user_mss must be done
972 * before the exchange of SYN's. If the initial ack from the other
973 * end has a window of 0, max_window and thus mss will both be 0.
974 */
975
976 /*
977 * Now we need to check if we have a half built packet.
978 */
979 #ifndef CONFIG_NO_PATH_MTU_DISCOVERY
980 /*
981 * FIXME: I'm almost sure that this fragment is BUG,
982 * but it works... I do not know why 8) --ANK
983 *
984 * Really, we should rebuild all the queues...
985 * It's difficult. Temprorary hack is to send all
986 * queued segments with allowed fragmentation.
987 */
988 {
989 int new_mss = min(sk->mtu, sk->max_window);
990 if (new_mss < sk->mss)
991 {
992 tcp_send_partial(sk);
993 sk->mss = new_mss;
994 }
995 }
996 #endif
997
998 if ((skb = tcp_dequeue_partial(sk)) != NULL)
999 {
1000 int tcp_size;
1001
1002 tcp_size = skb->tail - (unsigned char *)(skb->h.th + 1);
1003
1004 /* Add more stuff to the end of skb->len */
1005 if (!(flags & MSG_OOB))
1006 {
1007 copy = min(sk->mss - tcp_size, seglen);
1008 if (copy <= 0)
1009 {
1010 printk("TCP: **bug**: \"copy\" <= 0\n");
1011 return -EFAULT;
1012 }
1013 tcp_size += copy;
1014 memcpy_fromfs(skb_put(skb,copy), from, copy);
1015 skb->csum = csum_partial(skb->tail - tcp_size, tcp_size, 0);
1016 from += copy;
1017 copied += copy;
1018 len -= copy;
1019 sk->write_seq += copy;
1020 seglen -= copy;
1021 }
1022 if (tcp_size >= sk->mss || (flags & MSG_OOB) || !sk->packets_out)
1023 tcp_send_skb(sk, skb);
1024 else
1025 tcp_enqueue_partial(skb, sk);
1026 continue;
1027 }
1028
1029 /*
1030 * We also need to worry about the window.
1031 * If window < 1/2 the maximum window we've seen from this
1032 * host, don't use it. This is sender side
1033 * silly window prevention, as specified in RFC1122.
1034 * (Note that this is different than earlier versions of
1035 * SWS prevention, e.g. RFC813.). What we actually do is
1036 * use the whole MSS. Since the results in the right
1037 * edge of the packet being outside the window, it will
1038 * be queued for later rather than sent.
1039 */
1040
1041 copy = sk->window_seq - sk->write_seq;
1042 if (copy <= 0 || copy < (sk->max_window >> 1) || copy > sk->mss)
1043 copy = sk->mss;
1044 if (copy > seglen)
1045 copy = seglen;
1046
1047 /*
1048 * We should really check the window here also.
1049 */
1050
1051 send_tmp = NULL;
1052 if (copy < sk->mss && !(flags & MSG_OOB) && sk->packets_out)
1053 {
1054 skb = sock_wmalloc(sk, sk->mtu + 128 + prot->max_header + 15, 0, GFP_KERNEL);
1055 send_tmp = skb;
1056 }
1057 else
1058 {
1059 skb = sock_wmalloc(sk, copy + prot->max_header + 15 , 0, GFP_KERNEL);
1060 }
1061
1062 /*
1063 * If we didn't get any memory, we need to sleep.
1064 */
1065
1066 if (skb == NULL)
1067 {
1068 sk->socket->flags |= SO_NOSPACE;
1069 if (nonblock)
1070 {
1071 if (copied)
1072 return copied;
1073 return -EAGAIN;
1074 }
1075
1076 if (current->signal & ~current->blocked)
1077 {
1078 if (copied)
1079 return copied;
1080 return -ERESTARTSYS;
1081 }
1082
1083 wait_for_tcp_memory(sk);
1084 continue;
1085 }
1086
1087 skb->sk = sk;
1088 skb->free = 0;
1089 skb->localroute = sk->localroute|(flags&MSG_DONTROUTE);
1090
1091 /*
1092 * FIXME: we need to optimize this.
1093 * Perhaps some hints here would be good.
1094 */
1095
1096 tmp = prot->build_header(skb, sk->saddr, sk->daddr, &dev,
1097 IPPROTO_TCP, sk->opt, skb->truesize,sk->ip_tos,sk->ip_ttl,&sk->ip_route_cache);
1098 if (tmp < 0 )
1099 {
1100 sock_wfree(sk, skb);
1101 if (copied)
1102 return(copied);
1103 return(tmp);
1104 }
1105 #ifndef CONFIG_NO_PATH_MTU_DISCOVERY
1106 skb->ip_hdr->frag_off |= htons(IP_DF);
1107 #endif
1108 skb->dev = dev;
1109 skb->h.th =(struct tcphdr *)skb_put(skb,sizeof(struct tcphdr));
1110 tmp = tcp_build_header(skb->h.th, sk, seglen-copy);
1111 if (tmp < 0)
1112 {
1113 sock_wfree(sk, skb);
1114 if (copied)
1115 return(copied);
1116 return(tmp);
1117 }
1118
1119 if (flags & MSG_OOB)
1120 {
1121 skb->h.th->urg = 1;
1122 skb->h.th->urg_ptr = ntohs(copy);
1123 }
1124
1125 skb->csum = csum_partial_copy_fromuser(from,
1126 skb_put(skb,copy), copy, 0);
1127
1128 from += copy;
1129 copied += copy;
1130 len -= copy;
1131 seglen -= copy;
1132 skb->free = 0;
1133 sk->write_seq += copy;
1134
1135 if (send_tmp != NULL)
1136 {
1137 tcp_enqueue_partial(send_tmp, sk);
1138 continue;
1139 }
1140 tcp_send_skb(sk, skb);
1141 }
1142 }
1143 sk->err = 0;
1144
1145 return copied;
1146 }
1147
1148
1149 static int tcp_sendmsg(struct sock *sk, struct msghdr *msg,
/* */
1150 int len, int nonblock, int flags)
1151 {
1152 int retval = -EINVAL;
1153
1154 /*
1155 * Do sanity checking for sendmsg/sendto/send
1156 */
1157
1158 if (flags & ~(MSG_OOB|MSG_DONTROUTE))
1159 goto out;
1160 if (msg->msg_name) {
1161 struct sockaddr_in *addr=(struct sockaddr_in *)msg->msg_name;
1162
1163 if (msg->msg_namelen < sizeof(*addr))
1164 goto out;
1165 if (addr->sin_family && addr->sin_family != AF_INET)
1166 goto out;
1167 retval = -ENOTCONN;
1168 if(sk->state == TCP_CLOSE)
1169 goto out;
1170 retval = -EISCONN;
1171 if (addr->sin_port != sk->dummy_th.dest)
1172 goto out;
1173 if (addr->sin_addr.s_addr != sk->daddr)
1174 goto out;
1175 }
1176
1177 lock_sock(sk);
1178 retval = do_tcp_sendmsg(sk, msg, len, nonblock, flags);
1179
1180 /*
1181 * Nagle's rule. Turn Nagle off with TCP_NODELAY for highly
1182 * interactive fast network servers. It's meant to be on and
1183 * it really improves the throughput though not the echo time
1184 * on my slow slip link - Alan
1185 *
1186 * If not nagling we can send on the before case too..
1187 */
1188
1189 if (sk->partial) {
1190 if (!sk->packets_out ||
1191 (sk->nonagle && before(sk->write_seq , sk->window_seq))) {
1192 tcp_send_partial(sk);
1193 }
1194 }
1195
1196 release_sock(sk);
1197
1198 out:
1199 return retval;
1200 }
1201
1202
1203 /*
1204 * Send an ack if one is backlogged at this point. Ought to merge
1205 * this with tcp_send_ack().
1206 * This is called for delayed acks also.
1207 */
1208
1209 void tcp_read_wakeup(struct sock *sk)
/* */
1210 {
1211 int tmp;
1212 struct device *dev = NULL;
1213 struct tcphdr *t1;
1214 struct sk_buff *buff;
1215
1216 if (!sk->ack_backlog)
1217 return;
1218
1219 /*
1220 * If we're closed, don't send an ack, or we'll get a RST
1221 * from the closed destination.
1222 */
1223 if ((sk->state == TCP_CLOSE) || (sk->state == TCP_TIME_WAIT))
1224 return;
1225
1226 /*
1227 * FIXME: we need to put code here to prevent this routine from
1228 * being called. Being called once in a while is ok, so only check
1229 * if this is the second time in a row.
1230 */
1231
1232 /*
1233 * We need to grab some memory, and put together an ack,
1234 * and then put it into the queue to be sent.
1235 */
1236
1237 buff = sock_wmalloc(sk,MAX_ACK_SIZE,1, GFP_ATOMIC);
1238 if (buff == NULL)
1239 {
1240 /* Try again real soon. */
1241 tcp_reset_xmit_timer(sk, TIME_WRITE, HZ);
1242 return;
1243 }
1244
1245 buff->sk = sk;
1246 buff->localroute = sk->localroute;
1247 buff->csum = 0;
1248
1249 /*
1250 * Put in the IP header and routing stuff.
1251 */
1252
1253 tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
1254 IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl,&sk->ip_route_cache);
1255 if (tmp < 0)
1256 {
1257 buff->free = 1;
1258 sock_wfree(sk, buff);
1259 return;
1260 }
1261
1262 t1 =(struct tcphdr *)skb_put(buff,sizeof(struct tcphdr));
1263
1264 memcpy(t1,(void *) &sk->dummy_th, sizeof(*t1));
1265 t1->seq = htonl(sk->sent_seq);
1266
1267 sk->ack_backlog = 0;
1268 sk->bytes_rcv = 0;
1269
1270 sk->window = tcp_select_window(sk);
1271 t1->window = htons(sk->window);
1272 t1->ack_seq = htonl(sk->acked_seq);
1273 t1->doff = sizeof(*t1)/4;
1274 tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), buff);
1275 sk->prot->queue_xmit(sk, dev, buff, 1);
1276 tcp_statistics.TcpOutSegs++;
1277 }
1278
1279
1280 /*
1281 * Handle reading urgent data. BSD has very simple semantics for
1282 * this, no blocking and very strange errors 8)
1283 */
1284
1285 static int tcp_recv_urg(struct sock * sk, int nonblock,
/* */
1286 struct msghdr *msg, int len, int flags, int *addr_len)
1287 {
1288 /*
1289 * No URG data to read
1290 */
1291 if (sk->urginline || !sk->urg_data || sk->urg_data == URG_READ)
1292 return -EINVAL; /* Yes this is right ! */
1293
1294 if (sk->err)
1295 return sock_error(sk);
1296
1297 if (sk->state == TCP_CLOSE || sk->done)
1298 {
1299 if (!sk->done)
1300 {
1301 sk->done = 1;
1302 return 0;
1303 }
1304 return -ENOTCONN;
1305 }
1306
1307 if (sk->shutdown & RCV_SHUTDOWN)
1308 {
1309 sk->done = 1;
1310 return 0;
1311 }
1312 lock_sock(sk);
1313 if (sk->urg_data & URG_VALID)
1314 {
1315 char c = sk->urg_data;
1316 if (!(flags & MSG_PEEK))
1317 sk->urg_data = URG_READ;
1318 memcpy_toiovec(msg->msg_iov, &c, 1);
1319 if(msg->msg_name)
1320 {
1321 struct sockaddr_in *sin=(struct sockaddr_in *)msg->msg_name;
1322 sin->sin_family=AF_INET;
1323 sin->sin_addr.s_addr=sk->daddr;
1324 sin->sin_port=sk->dummy_th.dest;
1325 }
1326 if(addr_len)
1327 *addr_len=sizeof(struct sockaddr_in);
1328 release_sock(sk);
1329 return 1;
1330 }
1331 release_sock(sk);
1332
1333 /*
1334 * Fixed the recv(..., MSG_OOB) behaviour. BSD docs and
1335 * the available implementations agree in this case:
1336 * this call should never block, independent of the
1337 * blocking state of the socket.
1338 * Mike <pall@rz.uni-karlsruhe.de>
1339 */
1340 return -EAGAIN;
1341 }
1342
1343 /*
1344 * Release a skb if it is no longer needed. This routine
1345 * must be called with interrupts disabled or with the
1346 * socket locked so that the sk_buff queue operation is ok.
1347 */
1348
1349 static inline void tcp_eat_skb(struct sock *sk, struct sk_buff * skb)
/* */
1350 {
1351 sk->ack_backlog++;
1352 skb->sk = sk;
1353 __skb_unlink(skb, &sk->receive_queue);
1354 kfree_skb(skb, FREE_READ);
1355 }
1356
1357 /*
1358 * FIXME:
1359 * This routine frees used buffers.
1360 * It should consider sending an ACK to let the
1361 * other end know we now have a bigger window.
1362 */
1363
1364 static void cleanup_rbuf(struct sock *sk)
/* */
1365 {
1366 struct sk_buff *skb;
1367 unsigned long rspace;
1368
1369 /*
1370 * NOTE! The socket must be locked, so that we don't get
1371 * a messed-up receive queue.
1372 */
1373 while ((skb=skb_peek(&sk->receive_queue)) != NULL) {
1374 if (!skb->used || skb->users)
1375 break;
1376 tcp_eat_skb(sk, skb);
1377 }
1378
1379 /*
1380 * FIXME:
1381 * At this point we should send an ack if the difference
1382 * in the window, and the amount of space is bigger than
1383 * TCP_WINDOW_DIFF.
1384 */
1385
1386 rspace=sock_rspace(sk);
1387 if(sk->debug)
1388 printk("sk->rspace = %lu\n", rspace);
1389 /*
1390 * This area has caused the most trouble. The current strategy
1391 * is to simply do nothing if the other end has room to send at
1392 * least 3 full packets, because the ack from those will auto-
1393 * matically update the window. If the other end doesn't think
1394 * we have much space left, but we have room for at least 1 more
1395 * complete packet than it thinks we do, we will send an ack
1396 * immediately. Otherwise we will wait up to .5 seconds in case
1397 * the user reads some more.
1398 */
1399
1400 /*
1401 * It's unclear whether to use sk->mtu or sk->mss here. They differ only
1402 * if the other end is offering a window smaller than the agreed on MSS
1403 * (called sk->mtu here). In theory there's no connection between send
1404 * and receive, and so no reason to think that they're going to send
1405 * small packets. For the moment I'm using the hack of reducing the mss
1406 * only on the send side, so I'm putting mtu here.
1407 */
1408
1409 if (rspace > (sk->window - sk->bytes_rcv + sk->mtu))
1410 {
1411 /* Send an ack right now. */
1412 tcp_read_wakeup(sk);
1413 }
1414 else
1415 {
1416 /* Force it to send an ack soon. */
1417 int was_active = del_timer(&sk->retransmit_timer);
1418 if (!was_active || jiffies+TCP_ACK_TIME < sk->timer.expires)
1419 {
1420 tcp_reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
1421 }
1422 else
1423 add_timer(&sk->retransmit_timer);
1424 }
1425 }
1426
1427
1428 /*
1429 * This routine copies from a sock struct into the user buffer.
1430 */
1431
1432 static int tcp_recvmsg(struct sock *sk, struct msghdr *msg,
/* */
1433 int len, int nonblock, int flags, int *addr_len)
1434 {
1435 struct wait_queue wait = { current, NULL };
1436 int copied = 0;
1437 u32 peek_seq;
1438 volatile u32 *seq; /* So gcc doesn't overoptimise */
1439 unsigned long used;
1440
1441 /*
1442 * This error should be checked.
1443 */
1444
1445 if (sk->state == TCP_LISTEN)
1446 return -ENOTCONN;
1447
1448 /*
1449 * Urgent data needs to be handled specially.
1450 */
1451
1452 if (flags & MSG_OOB)
1453 return tcp_recv_urg(sk, nonblock, msg, len, flags, addr_len);
1454
1455 /*
1456 * Copying sequence to update. This is volatile to handle
1457 * the multi-reader case neatly (memcpy_to/fromfs might be
1458 * inline and thus not flush cached variables otherwise).
1459 */
1460
1461 peek_seq = sk->copied_seq;
1462 seq = &sk->copied_seq;
1463 if (flags & MSG_PEEK)
1464 seq = &peek_seq;
1465
1466 add_wait_queue(sk->sleep, &wait);
1467 lock_sock(sk);
1468 while (len > 0)
1469 {
1470 struct sk_buff * skb;
1471 u32 offset;
1472
1473 /*
1474 * Are we at urgent data? Stop if we have read anything.
1475 */
1476
1477 if (copied && sk->urg_data && sk->urg_seq == *seq)
1478 break;
1479
1480 /*
1481 * Next get a buffer.
1482 */
1483
1484 current->state = TASK_INTERRUPTIBLE;
1485
1486 skb = skb_peek(&sk->receive_queue);
1487 do
1488 {
1489 if (!skb)
1490 break;
1491 if (before(*seq, skb->seq))
1492 break;
1493 offset = *seq - skb->seq;
1494 if (skb->h.th->syn)
1495 offset--;
1496 if (offset < skb->len)
1497 goto found_ok_skb;
1498 if (skb->h.th->fin)
1499 goto found_fin_ok;
1500 if (!(flags & MSG_PEEK))
1501 skb->used = 1;
1502 skb = skb->next;
1503 }
1504 while (skb != (struct sk_buff *)&sk->receive_queue);
1505
1506 if (copied)
1507 break;
1508
1509 if (sk->err)
1510 {
1511 copied = sock_error(sk);
1512 break;
1513 }
1514
1515 if (sk->state == TCP_CLOSE)
1516 {
1517 if (!sk->done)
1518 {
1519 sk->done = 1;
1520 break;
1521 }
1522 copied = -ENOTCONN;
1523 break;
1524 }
1525
1526 if (sk->shutdown & RCV_SHUTDOWN)
1527 {
1528 sk->done = 1;
1529 break;
1530 }
1531
1532 if (nonblock)
1533 {
1534 copied = -EAGAIN;
1535 break;
1536 }
1537
1538 cleanup_rbuf(sk);
1539 release_sock(sk);
1540 sk->socket->flags |= SO_WAITDATA;
1541 schedule();
1542 sk->socket->flags &= ~SO_WAITDATA;
1543 lock_sock(sk);
1544
1545 if (current->signal & ~current->blocked)
1546 {
1547 copied = -ERESTARTSYS;
1548 break;
1549 }
1550 continue;
1551
1552 found_ok_skb:
1553 /*
1554 * Lock the buffer. We can be fairly relaxed as
1555 * an interrupt will never steal a buffer we are
1556 * using unless I've missed something serious in
1557 * tcp_data.
1558 */
1559
1560 skb->users++;
1561
1562 /*
1563 * Ok so how much can we use ?
1564 */
1565
1566 used = skb->len - offset;
1567 if (len < used)
1568 used = len;
1569 /*
1570 * Do we have urgent data here?
1571 */
1572
1573 if (sk->urg_data)
1574 {
1575 u32 urg_offset = sk->urg_seq - *seq;
1576 if (urg_offset < used)
1577 {
1578 if (!urg_offset)
1579 {
1580 if (!sk->urginline)
1581 {
1582 ++*seq;
1583 offset++;
1584 used--;
1585 }
1586 }
1587 else
1588 used = urg_offset;
1589 }
1590 }
1591
1592 /*
1593 * Copy it - We _MUST_ update *seq first so that we
1594 * don't ever double read when we have dual readers
1595 */
1596
1597 *seq += used;
1598
1599 /*
1600 * This memcpy_tofs can sleep. If it sleeps and we
1601 * do a second read it relies on the skb->users to avoid
1602 * a crash when cleanup_rbuf() gets called.
1603 */
1604
1605 memcpy_toiovec(msg->msg_iov,((unsigned char *)skb->h.th) +
1606 skb->h.th->doff*4 + offset, used);
1607 copied += used;
1608 len -= used;
1609
1610 /*
1611 * We now will not sleep again until we are finished
1612 * with skb. Sorry if you are doing the SMP port
1613 * but you'll just have to fix it neatly ;)
1614 */
1615
1616 skb->users --;
1617
1618 if (after(sk->copied_seq,sk->urg_seq))
1619 sk->urg_data = 0;
1620 if (used + offset < skb->len)
1621 continue;
1622
1623 /*
1624 * Process the FIN.
1625 */
1626
1627 if (skb->h.th->fin)
1628 goto found_fin_ok;
1629 if (flags & MSG_PEEK)
1630 continue;
1631 skb->used = 1;
1632 if (!skb->users)
1633 tcp_eat_skb(sk, skb);
1634 continue;
1635
1636 found_fin_ok:
1637 ++*seq;
1638 if (flags & MSG_PEEK)
1639 break;
1640
1641 /*
1642 * All is done
1643 */
1644
1645 skb->used = 1;
1646 sk->shutdown |= RCV_SHUTDOWN;
1647 break;
1648
1649 }
1650
1651 if(copied>0 && msg->msg_name)
1652 {
1653 struct sockaddr_in *sin=(struct sockaddr_in *)msg->msg_name;
1654 sin->sin_family=AF_INET;
1655 sin->sin_addr.s_addr=sk->daddr;
1656 sin->sin_port=sk->dummy_th.dest;
1657 }
1658 if(addr_len)
1659 *addr_len=sizeof(struct sockaddr_in);
1660
1661 remove_wait_queue(sk->sleep, &wait);
1662 current->state = TASK_RUNNING;
1663
1664 /* Clean up data we have read: This will do ACK frames */
1665 cleanup_rbuf(sk);
1666 release_sock(sk);
1667 return copied;
1668 }
1669
1670
1671
1672 /*
1673 * State processing on a close. This implements the state shift for
1674 * sending our FIN frame. Note that we only send a FIN for some
1675 * states. A shutdown() may have already sent the FIN, or we may be
1676 * closed.
1677 */
1678
1679 static int tcp_close_state(struct sock *sk, int dead)
/* */
1680 {
1681 int ns=TCP_CLOSE;
1682 int send_fin=0;
1683 switch(sk->state)
1684 {
1685 case TCP_SYN_SENT: /* No SYN back, no FIN needed */
1686 break;
1687 case TCP_SYN_RECV:
1688 case TCP_ESTABLISHED: /* Closedown begin */
1689 ns=TCP_FIN_WAIT1;
1690 send_fin=1;
1691 break;
1692 case TCP_FIN_WAIT1: /* Already closing, or FIN sent: no change */
1693 case TCP_FIN_WAIT2:
1694 case TCP_CLOSING:
1695 ns=sk->state;
1696 break;
1697 case TCP_CLOSE:
1698 case TCP_LISTEN:
1699 break;
1700 case TCP_CLOSE_WAIT: /* They have FIN'd us. We send our FIN and
1701 wait only for the ACK */
1702 ns=TCP_LAST_ACK;
1703 send_fin=1;
1704 }
1705
1706 tcp_set_state(sk,ns);
1707
1708 /*
1709 * This is a (useful) BSD violating of the RFC. There is a
1710 * problem with TCP as specified in that the other end could
1711 * keep a socket open forever with no application left this end.
1712 * We use a 3 minute timeout (about the same as BSD) then kill
1713 * our end. If they send after that then tough - BUT: long enough
1714 * that we won't make the old 4*rto = almost no time - whoops
1715 * reset mistake.
1716 */
1717 if(dead && ns==TCP_FIN_WAIT2)
1718 {
1719 int timer_active=del_timer(&sk->timer);
1720 if(timer_active)
1721 add_timer(&sk->timer);
1722 else
1723 tcp_reset_msl_timer(sk, TIME_CLOSE, TCP_FIN_TIMEOUT);
1724 }
1725
1726 return send_fin;
1727 }
1728
1729 /*
1730 * Shutdown the sending side of a connection. Much like close except
1731 * that we don't receive shut down or set sk->dead=1.
1732 */
1733
1734 void tcp_shutdown(struct sock *sk, int how)
/* */
1735 {
1736 /*
1737 * We need to grab some memory, and put together a FIN,
1738 * and then put it into the queue to be sent.
1739 * Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
1740 */
1741
1742 if (!(how & SEND_SHUTDOWN))
1743 return;
1744
1745 /*
1746 * If we've already sent a FIN, or it's a closed state
1747 */
1748
1749 if (sk->state == TCP_FIN_WAIT1 ||
1750 sk->state == TCP_FIN_WAIT2 ||
1751 sk->state == TCP_CLOSING ||
1752 sk->state == TCP_LAST_ACK ||
1753 sk->state == TCP_TIME_WAIT ||
1754 sk->state == TCP_CLOSE ||
1755 sk->state == TCP_LISTEN
1756 )
1757 {
1758 return;
1759 }
1760 lock_sock(sk);
1761
1762 /*
1763 * flag that the sender has shutdown
1764 */
1765
1766 sk->shutdown |= SEND_SHUTDOWN;
1767
1768 /*
1769 * Clear out any half completed packets.
1770 */
1771
1772 if (sk->partial)
1773 tcp_send_partial(sk);
1774
1775 /*
1776 * FIN if needed
1777 */
1778
1779 if (tcp_close_state(sk,0))
1780 tcp_send_fin(sk);
1781
1782 release_sock(sk);
1783 }
1784
1785
1786 /*
1787 * Return 1 if we still have things to send in our buffers.
1788 */
1789
1790 static inline int closing(struct sock * sk)
/* */
1791 {
1792 switch (sk->state) {
1793 case TCP_FIN_WAIT1:
1794 case TCP_CLOSING:
1795 case TCP_LAST_ACK:
1796 return 1;
1797 }
1798 return 0;
1799 }
1800
1801
1802 static void tcp_close(struct sock *sk, unsigned long timeout)
/* */
1803 {
1804 struct sk_buff *skb;
1805
1806 /*
1807 * We need to grab some memory, and put together a FIN,
1808 * and then put it into the queue to be sent.
1809 */
1810
1811 lock_sock(sk);
1812
1813 tcp_cache_zap();
1814 if(sk->state == TCP_LISTEN)
1815 {
1816 /* Special case */
1817 tcp_set_state(sk, TCP_CLOSE);
1818 tcp_close_pending(sk);
1819 release_sock(sk);
1820 return;
1821 }
1822
1823 sk->keepopen = 1;
1824 sk->shutdown = SHUTDOWN_MASK;
1825
1826 if (!sk->dead)
1827 sk->state_change(sk);
1828
1829 /*
1830 * We need to flush the recv. buffs. We do this only on the
1831 * descriptor close, not protocol-sourced closes, because the
1832 * reader process may not have drained the data yet!
1833 */
1834
1835 while((skb=skb_dequeue(&sk->receive_queue))!=NULL)
1836 kfree_skb(skb, FREE_READ);
1837
1838 /*
1839 * Get rid off any half-completed packets.
1840 */
1841
1842 if (sk->partial)
1843 tcp_send_partial(sk);
1844
1845 /*
1846 * Timeout is not the same thing - however the code likes
1847 * to send both the same way (sigh).
1848 */
1849
1850 if (tcp_close_state(sk,1)==1)
1851 {
1852 tcp_send_fin(sk);
1853 }
1854
1855 if (timeout) {
1856 cli();
1857 release_sock(sk);
1858 current->timeout = timeout;
1859 while(closing(sk) && current->timeout)
1860 {
1861 interruptible_sleep_on(sk->sleep);
1862 if (current->signal & ~current->blocked)
1863 {
1864 break;
1865 }
1866 }
1867 current->timeout=0;
1868 lock_sock(sk);
1869 sti();
1870 }
1871
1872 /*
1873 * This will destroy it. The timers will take care of actually
1874 * free'ing up the memory.
1875 */
1876 sk->dead = 1;
1877 tcp_cache_zap(); /* Kill the cache again. */
1878 release_sock(sk);
1879 }
1880
1881
1882 /*
1883 * This will accept the next outstanding connection.
1884 */
1885
1886 static struct sock *tcp_accept(struct sock *sk, int flags)
/* */
1887 {
1888 struct sock *newsk;
1889 struct sk_buff *skb;
1890
1891 /*
1892 * We need to make sure that this socket is listening,
1893 * and that it has something pending.
1894 */
1895
1896 if (sk->state != TCP_LISTEN)
1897 {
1898 sk->err = EINVAL;
1899 return(NULL);
1900 }
1901
1902 /* Avoid the race. */
1903 cli();
1904 lock_sock(sk);
1905
1906 while((skb = tcp_dequeue_established(sk)) == NULL)
1907 {
1908 if (flags & O_NONBLOCK)
1909 {
1910 sti();
1911 release_sock(sk);
1912 sk->err = EAGAIN;
1913 return(NULL);
1914 }
1915
1916 release_sock(sk);
1917 interruptible_sleep_on(sk->sleep);
1918 if (current->signal & ~current->blocked)
1919 {
1920 sti();
1921 sk->err = ERESTARTSYS;
1922 return(NULL);
1923 }
1924 lock_sock(sk);
1925 }
1926 sti();
1927
1928 /*
1929 * Now all we need to do is return skb->sk.
1930 */
1931
1932 newsk = skb->sk;
1933
1934 kfree_skb(skb, FREE_READ);
1935 sk->ack_backlog--;
1936 release_sock(sk);
1937 return(newsk);
1938 }
1939
1940 /*
1941 * This will initiate an outgoing connection.
1942 */
1943
1944 static int tcp_connect(struct sock *sk, struct sockaddr_in *usin, int addr_len)
/* */
1945 {
1946 struct sk_buff *buff;
1947 struct device *dev=NULL;
1948 unsigned char *ptr;
1949 int tmp;
1950 int atype;
1951 struct tcphdr *t1;
1952 struct rtable *rt;
1953
1954 if (sk->state != TCP_CLOSE)
1955 return(-EISCONN);
1956
1957 /*
1958 * Don't allow a double connect.
1959 */
1960
1961 if(sk->daddr)
1962 return -EINVAL;
1963
1964 if (addr_len < 8)
1965 return(-EINVAL);
1966
1967 if (usin->sin_family && usin->sin_family != AF_INET)
1968 return(-EAFNOSUPPORT);
1969
1970 /*
1971 * connect() to INADDR_ANY means loopback (BSD'ism).
1972 */
1973
1974 if(usin->sin_addr.s_addr==INADDR_ANY)
1975 usin->sin_addr.s_addr=ip_my_addr();
1976
1977 /*
1978 * Don't want a TCP connection going to a broadcast address
1979 */
1980
1981 if ((atype=ip_chk_addr(usin->sin_addr.s_addr)) == IS_BROADCAST || atype==IS_MULTICAST)
1982 return -ENETUNREACH;
1983
1984 lock_sock(sk);
1985 sk->daddr = usin->sin_addr.s_addr;
1986 sk->write_seq = tcp_init_seq();
1987 sk->window_seq = sk->write_seq;
1988 sk->rcv_ack_seq = sk->write_seq -1;
1989 sk->err = 0;
1990 sk->dummy_th.dest = usin->sin_port;
1991 release_sock(sk);
1992
1993 buff = sock_wmalloc(sk,MAX_SYN_SIZE,0, GFP_KERNEL);
1994 if (buff == NULL)
1995 {
1996 return(-ENOMEM);
1997 }
1998 lock_sock(sk);
1999 buff->sk = sk;
2000 buff->free = 0;
2001 buff->localroute = sk->localroute;
2002
2003
2004 /*
2005 * Put in the IP header and routing stuff.
2006 */
2007
2008 tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
2009 IPPROTO_TCP, NULL, MAX_SYN_SIZE,sk->ip_tos,sk->ip_ttl,&sk->ip_route_cache);
2010 if (tmp < 0)
2011 {
2012 sock_wfree(sk, buff);
2013 release_sock(sk);
2014 return(-ENETUNREACH);
2015 }
2016 if ((rt = sk->ip_route_cache) != NULL && !sk->saddr)
2017 sk->saddr = rt->rt_src;
2018 sk->rcv_saddr = sk->saddr;
2019
2020 t1 = (struct tcphdr *) skb_put(buff,sizeof(struct tcphdr));
2021
2022 memcpy(t1,(void *)&(sk->dummy_th), sizeof(*t1));
2023 buff->seq = sk->write_seq++;
2024 t1->seq = htonl(buff->seq);
2025 sk->sent_seq = sk->write_seq;
2026 buff->end_seq = sk->write_seq;
2027 t1->ack = 0;
2028 t1->window = 2;
2029 t1->syn = 1;
2030 t1->doff = 6;
2031 /* use 512 or whatever user asked for */
2032
2033 if(rt!=NULL && (rt->rt_flags&RTF_WINDOW))
2034 sk->window_clamp=rt->rt_window;
2035 else
2036 sk->window_clamp=0;
2037
2038 if (sk->user_mss)
2039 sk->mtu = sk->user_mss;
2040 else if (rt)
2041 sk->mtu = rt->rt_mtu - sizeof(struct iphdr) - sizeof(struct tcphdr);
2042 else
2043 sk->mtu = 576 - sizeof(struct iphdr) - sizeof(struct tcphdr);
2044
2045 /*
2046 * but not bigger than device MTU
2047 */
2048
2049 if(sk->mtu <32)
2050 sk->mtu = 32; /* Sanity limit */
2051
2052 sk->mtu = min(sk->mtu, dev->mtu - sizeof(struct iphdr) - sizeof(struct tcphdr));
2053
2054 #ifdef CONFIG_SKIP
2055
2056 /*
2057 * SKIP devices set their MTU to 65535. This is so they can take packets
2058 * unfragmented to security process then fragment. They could lie to the
2059 * TCP layer about a suitable MTU, but its easier to let skip sort it out
2060 * simply because the final package we want unfragmented is going to be
2061 *
2062 * [IPHDR][IPSP][Security data][Modified TCP data][Security data]
2063 */
2064
2065 if(skip_pick_mtu!=NULL) /* If SKIP is loaded.. */
2066 sk->mtu=skip_pick_mtu(sk->mtu,dev);
2067 #endif
2068
2069 /*
2070 * Put in the TCP options to say MTU.
2071 */
2072
2073 ptr = skb_put(buff,4);
2074 ptr[0] = 2;
2075 ptr[1] = 4;
2076 ptr[2] = (sk->mtu) >> 8;
2077 ptr[3] = (sk->mtu) & 0xff;
2078 buff->csum = csum_partial(ptr, 4, 0);
2079 tcp_send_check(t1, sk->saddr, sk->daddr,
2080 sizeof(struct tcphdr) + 4, buff);
2081
2082 /*
2083 * This must go first otherwise a really quick response will get reset.
2084 */
2085
2086 tcp_cache_zap();
2087 tcp_set_state(sk,TCP_SYN_SENT);
2088 if(rt&&rt->rt_flags&RTF_IRTT)
2089 sk->rto = rt->rt_irtt;
2090 else
2091 sk->rto = TCP_TIMEOUT_INIT;
2092 sk->retransmit_timer.function=&tcp_retransmit_timer;
2093 sk->retransmit_timer.data = (unsigned long)sk;
2094 tcp_reset_xmit_timer(sk, TIME_WRITE, sk->rto); /* Timer for repeating the SYN until an answer */
2095 sk->retransmits = 0; /* Now works the right way instead of a hacked
2096 initial setting */
2097
2098 sk->prot->queue_xmit(sk, dev, buff, 0);
2099 tcp_reset_xmit_timer(sk, TIME_WRITE, sk->rto);
2100 tcp_statistics.TcpActiveOpens++;
2101 tcp_statistics.TcpOutSegs++;
2102
2103 release_sock(sk);
2104 return(0);
2105 }
2106
2107 /*
2108 * Socket option code for TCP.
2109 */
2110
2111 int tcp_setsockopt(struct sock *sk, int level, int optname, char *optval, int optlen)
/* */
2112 {
2113 int val,err;
2114
2115 if(level!=SOL_TCP)
2116 return ip_setsockopt(sk,level,optname,optval,optlen);
2117
2118 if (optval == NULL)
2119 return(-EINVAL);
2120
2121 err=verify_area(VERIFY_READ, optval, sizeof(int));
2122 if(err)
2123 return err;
2124
2125 val = get_user((int *)optval);
2126
2127 switch(optname)
2128 {
2129 case TCP_MAXSEG:
2130 /*
2131 * values greater than interface MTU won't take effect. however at
2132 * the point when this call is done we typically don't yet know
2133 * which interface is going to be used
2134 */
2135 if(val<1||val>MAX_WINDOW)
2136 return -EINVAL;
2137 sk->user_mss=val;
2138 return 0;
2139 case TCP_NODELAY:
2140 sk->nonagle=(val==0)?0:1;
2141 return 0;
2142 default:
2143 return(-ENOPROTOOPT);
2144 }
2145 }
2146
2147 int tcp_getsockopt(struct sock *sk, int level, int optname, char *optval, int *optlen)
/* ![[last]](../icons/n_last.png)
*/
2148 {
2149 int val,err;
2150
2151 if(level!=SOL_TCP)
2152 return ip_getsockopt(sk,level,optname,optval,optlen);
2153
2154 switch(optname)
2155 {
2156 case TCP_MAXSEG:
2157 val=sk->user_mss;
2158 break;
2159 case TCP_NODELAY:
2160 val=sk->nonagle;
2161 break;
2162 default:
2163 return(-ENOPROTOOPT);
2164 }
2165 err=verify_area(VERIFY_WRITE, optlen, sizeof(int));
2166 if(err)
2167 return err;
2168 put_user(sizeof(int),(int *) optlen);
2169
2170 err=verify_area(VERIFY_WRITE, optval, sizeof(int));
2171 if(err)
2172 return err;
2173 put_user(val,(int *)optval);
2174
2175 return(0);
2176 }
2177
2178
2179 struct proto tcp_prot = {
2180 tcp_close,
2181 ip_build_header,
2182 tcp_connect,
2183 tcp_accept,
2184 ip_queue_xmit,
2185 tcp_retransmit,
2186 tcp_write_wakeup,
2187 tcp_read_wakeup,
2188 tcp_rcv,
2189 tcp_select,
2190 tcp_ioctl,
2191 NULL,
2192 tcp_shutdown,
2193 tcp_setsockopt,
2194 tcp_getsockopt,
2195 tcp_sendmsg,
2196 tcp_recvmsg,
2197 NULL, /* No special bind() */
2198 128,
2199 0,
2200 "TCP",
2201 0, 0,
2202 {NULL,}
2203 };
![[bottom]](../icons/n_bottom.png){kind=icon}
*/