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 sk->inuse=1 26 * and was trying to connect (tcp_err()). 27 * Alan Cox : All icmp error handling was broken 28 * pointers passed where wrong and the 29 * socket was looked up backwards. Nobody 30 * tested any icmp error code obviously. 31 * Alan Cox : tcp_err() now handled properly. It wakes people 32 * on errors. select behaves and the icmp error race 33 * has gone by moving it into sock.c 34 * Alan Cox : tcp_reset() fixed to work for everything not just 35 * packets for unknown sockets. 36 * Alan Cox : tcp option processing. 37 * Alan Cox : Reset tweaked (still not 100%) [Had syn rule wrong] 38 * Herp Rosmanith : More reset fixes 39 * Alan Cox : No longer acks invalid rst frames. Acking 40 * any kind of RST is right out. 41 * Alan Cox : Sets an ignore me flag on an rst receive 42 * otherwise odd bits of prattle escape still 43 * Alan Cox : Fixed another acking RST frame bug. Should stop 44 * LAN workplace lockups. 45 * Alan Cox : Some tidyups using the new skb list facilities 46 * Alan Cox : sk->keepopen now seems to work 47 * Alan Cox : Pulls options out correctly on accepts 48 * Alan Cox : Fixed assorted sk->rqueue->next errors 49 * Alan Cox : PSH doesn't end a TCP read. Switched a bit to skb ops. 50 * Alan Cox : Tidied tcp_data to avoid a potential nasty. 51 * Alan Cox : Added some better commenting, as the tcp is hard to follow 52 * Alan Cox : Removed incorrect check for 20 * psh 53 * Michael O'Reilly : ack < copied bug fix. 54 * Johannes Stille : Misc tcp fixes (not all in yet). 55 * Alan Cox : FIN with no memory -> CRASH 56 * Alan Cox : Added socket option proto entries. Also added awareness of them to accept. 57 * Alan Cox : Added TCP options (SOL_TCP) 58 * Alan Cox : Switched wakeup calls to callbacks, so the kernel can layer network sockets. 59 * Alan Cox : Use ip_tos/ip_ttl settings. 60 * Alan Cox : Handle FIN (more) properly (we hope). 61 * Alan Cox : RST frames sent on unsynchronised state ack error/ 62 * Alan Cox : Put in missing check for SYN bit. 63 * Alan Cox : Added tcp_select_window() aka NET2E 64 * window non shrink trick. 65 * Alan Cox : Added a couple of small NET2E timer fixes 66 * Charles Hedrick : TCP fixes 67 * Toomas Tamm : TCP window fixes 68 * Alan Cox : Small URG fix to rlogin ^C ack fight 69 * Charles Hedrick : Rewrote most of it to actually work 70 * Linus : Rewrote tcp_read() and URG handling 71 * completely 72 * Gerhard Koerting: Fixed some missing timer handling 73 * Matthew Dillon : Reworked TCP machine states as per RFC 74 * Gerhard Koerting: PC/TCP workarounds 75 * Adam Caldwell : Assorted timer/timing errors 76 * Matthew Dillon : Fixed another RST bug 77 * Alan Cox : Move to kernel side addressing changes. 78 * Alan Cox : Beginning work on TCP fastpathing (not yet usable) 79 * Arnt Gulbrandsen: Turbocharged tcp_check() routine. 80 * Alan Cox : TCP fast path debugging 81 * Alan Cox : Window clamping 82 * Michael Riepe : Bug in tcp_check() 83 * Matt Dillon : More TCP improvements and RST bug fixes 84 * Matt Dillon : Yet more small nasties remove from the TCP code 85 * (Be very nice to this man if tcp finally works 100%) 8) 86 * Alan Cox : BSD accept semantics. 87 * Alan Cox : Reset on closedown bug. 88 * Peter De Schrijver : ENOTCONN check missing in tcp_sendto(). 89 * Michael Pall : Handle select() after URG properly in all cases. 90 * Michael Pall : Undo the last fix in tcp_read_urg() (multi URG PUSH broke rlogin). 91 * Michael Pall : Fix the multi URG PUSH problem in tcp_readable(), select() after URG works now. 92 * Michael Pall : recv(...,MSG_OOB) never blocks in the BSD api. 93 * Alan Cox : Changed the semantics of sk->socket to 94 * fix a race and a signal problem with 95 * accept() and async I/O. 96 * Alan Cox : Relaxed the rules on tcp_sendto(). 97 * Yury Shevchuk : Really fixed accept() blocking problem. 98 * Craig I. Hagan : Allow for BSD compatible TIME_WAIT for 99 * clients/servers which listen in on 100 * fixed ports. 101 * Alan Cox : Cleaned the above up and shrank it to 102 * a sensible code size. 103 * Alan Cox : Self connect lockup fix. 104 * Alan Cox : No connect to multicast. 105 * Ross Biro : Close unaccepted children on master 106 * socket close. 107 * Alan Cox : Reset tracing code. 108 * Alan Cox : Spurious resets on shutdown. 109 * Alan Cox : Giant 15 minute/60 second timer error 110 * Alan Cox : Small whoops in selecting before an accept. 111 * Alan Cox : Kept the state trace facility since it's 112 * handy for debugging. 113 * Alan Cox : More reset handler fixes. 114 * Alan Cox : Started rewriting the code based on the RFC's 115 * for other useful protocol references see: 116 * Comer, KA9Q NOS, and for a reference on the 117 * difference between specifications and how BSD 118 * works see the 4.4lite source. 119 * A.N.Kuznetsov : Don't time wait on completion of tidy 120 * close. 121 * Linus Torvalds : Fin/Shutdown & copied_seq changes. 122 * Linus Torvalds : Fixed BSD port reuse to work first syn 123 * Alan Cox : Reimplemented timers as per the RFC and using multiple 124 * timers for sanity. 125 * Alan Cox : Small bug fixes, and a lot of new 126 * comments. 127 * Alan Cox : Fixed dual reader crash by locking 128 * the buffers (much like datagram.c) 129 * Alan Cox : Fixed stuck sockets in probe. A probe 130 * now gets fed up of retrying without 131 * (even a no space) answer. 132 * Alan Cox : Extracted closing code better 133 * Alan Cox : Fixed the closing state machine to 134 * resemble the RFC. 135 * Alan Cox : More 'per spec' fixes. 136 * Jorge Cwik : Even faster checksumming. 137 * Alan Cox : tcp_data() doesn't ack illegal PSH 138 * only frames. At least one pc tcp stack 139 * generates them. 140 * Alan Cox : Cache last socket. 141 * Alan Cox : Per route irtt. 142 * Matt Day : Select() match BSD precisely on error 143 * Alan Cox : New buffers 144 * Mark Tamsky : Various sk->prot->retransmits and 145 * sk->retransmits misupdating fixed. 146 * Fixed tcp_write_timeout: stuck close, 147 * and TCP syn retries gets used now. 148 * Mark Yarvis : In tcp_read_wakeup(), don't send an 149 * ack if stat is TCP_CLOSED. 150 * Alan Cox : Look up device on a retransmit - routes may 151 * change. Doesn't yet cope with MSS shrink right 152 * but its a start! 153 * 154 * 155 * To Fix: 156 * Fast path the code. Two things here - fix the window calculation 157 * so it doesn't iterate over the queue, also spot packets with no funny 158 * options arriving in order and process directly. 159 * 160 * Implement RFC 1191 [Path MTU discovery] 161 * Look at the effect of implementing RFC 1337 suggestions and their impact. 162 * Rewrite output state machine to use a single queue and do low window 163 * situations as per the spec (RFC 1122) 164 * Speed up input assembly algorithm. 165 * RFC1323 - PAWS and window scaling. PAWS is required for IPv6 so we 166 * could do with it working on IPv4 167 * User settable/learned rtt/max window/mtu 168 * Cope with MTU/device switches when retransmitting in tcp. 169 * Fix the window handling to use PR's new code. 170 * 171 * Change the fundamental structure to a single send queue maintained 172 * by TCP (removing the bogus ip stuff [thus fixing mtu drops on 173 * active routes too]). Cut the queue off in tcp_retransmit/ 174 * tcp_transmit. 175 * Change the receive queue to assemble as it goes. This lets us 176 * dispose of most of tcp_sequence, half of tcp_ack and chunks of 177 * tcp_data/tcp_read as well as the window shrink crud. 178 * Separate out duplicated code - tcp_alloc_skb, tcp_build_ack 179 * tcp_queue_skb seem obvious routines to extract. 180 * 181 * This program is free software; you can redistribute it and/or 182 * modify it under the terms of the GNU General Public License 183 * as published by the Free Software Foundation; either version 184 * 2 of the License, or(at your option) any later version. 185 * 186 * Description of States: 187 * 188 * TCP_SYN_SENT sent a connection request, waiting for ack 189 * 190 * TCP_SYN_RECV received a connection request, sent ack, 191 * waiting for final ack in three-way handshake. 192 * 193 * TCP_ESTABLISHED connection established 194 * 195 * TCP_FIN_WAIT1 our side has shutdown, waiting to complete 196 * transmission of remaining buffered data 197 * 198 * TCP_FIN_WAIT2 all buffered data sent, waiting for remote 199 * to shutdown 200 * 201 * TCP_CLOSING both sides have shutdown but we still have 202 * data we have to finish sending 203 * 204 * TCP_TIME_WAIT timeout to catch resent junk before entering 205 * closed, can only be entered from FIN_WAIT2 206 * or CLOSING. Required because the other end 207 * may not have gotten our last ACK causing it 208 * to retransmit the data packet (which we ignore) 209 * 210 * TCP_CLOSE_WAIT remote side has shutdown and is waiting for 211 * us to finish writing our data and to shutdown 212 * (we have to close() to move on to LAST_ACK) 213 * 214 * TCP_LAST_ACK out side has shutdown after remote has 215 * shutdown. There may still be data in our 216 * buffer that we have to finish sending 217 * 218 * TCP_CLOSE socket is finished 219 */ 220
221 #include <linux/types.h>
222 #include <linux/sched.h>
223 #include <linux/mm.h>
224 #include <linux/time.h>
225 #include <linux/string.h>
226 #include <linux/config.h>
227 #include <linux/socket.h>
228 #include <linux/sockios.h>
229 #include <linux/termios.h>
230 #include <linux/in.h>
231 #include <linux/fcntl.h>
232 #include <linux/inet.h>
233 #include <linux/netdevice.h>
234 #include <net/snmp.h>
235 #include <net/ip.h>
236 #include <net/protocol.h>
237 #include <net/icmp.h>
238 #include <net/tcp.h>
239 #include <net/arp.h>
240 #include <linux/skbuff.h>
241 #include <net/sock.h>
242 #include <net/route.h>
243 #include <linux/errno.h>
244 #include <linux/timer.h>
245 #include <asm/system.h>
246 #include <asm/segment.h>
247 #include <linux/mm.h>
248 #include <net/checksum.h>
249
250 /* 251 * The MSL timer is the 'normal' timer. 252 */ 253
254 #definereset_msl_timer(x,y,z) reset_timer(x,y,z)
255
256 #define SEQ_TICK 3
257 unsignedlongseq_offset;
258 structtcp_mibtcp_statistics;
259
260 /* 261 * Cached last hit socket 262 */ 263
264 volatileunsignedlongth_cache_saddr,th_cache_daddr;
265 volatileunsignedshortth_cache_dport, th_cache_sport;
266 volatilestructsock *th_cache_sk;
267
268 voidtcp_cache_zap(void)
/* */ 269 { 270 unsignedlongflags;
271 save_flags(flags);
272 cli();
273 th_cache_saddr=0;
274 th_cache_daddr=0;
275 th_cache_dport=0;
276 th_cache_sport=0;
277 th_cache_sk=NULL;
278 restore_flags(flags);
279 } 280
281 staticvoidtcp_close(structsock *sk, inttimeout);
282
283
284 /* 285 * The less said about this the better, but it works and will do for 1.2 286 */ 287
288 staticstructwait_queue *master_select_wakeup;
289
290 static__inline__intmin(unsignedinta, unsignedintb)
/* */ 291 { 292 if (a < b)
293 return(a);
294 return(b);
295 } 296
297 #undefSTATE_TRACE 298
299 #ifdefSTATE_TRACE 300 staticchar *statename[]={ 301 "Unused","Established","Syn Sent","Syn Recv",
302 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
303 "Close Wait","Last ACK","Listen","Closing"
304 };
305 #endif 306
307 static__inline__voidtcp_set_state(structsock *sk, intstate)
/* */ 308 { 309 if(sk->state==TCP_ESTABLISHED)
310 tcp_statistics.TcpCurrEstab--;
311 #ifdefSTATE_TRACE 312 if(sk->debug)
313 printk("TCP sk=%p, State %s -> %s\n",sk, statename[sk->state],statename[state]);
314 #endif 315 /* This is a hack but it doesn't occur often and it's going to 316 be a real to fix nicely */ 317
318 if(state==TCP_ESTABLISHED && sk->state==TCP_SYN_RECV)
319 { 320 wake_up_interruptible(&master_select_wakeup);
321 } 322 sk->state=state;
323 if(state==TCP_ESTABLISHED)
324 tcp_statistics.TcpCurrEstab++;
325 } 326
327 /* 328 * This routine picks a TCP windows for a socket based on 329 * the following constraints 330 * 331 * 1. The window can never be shrunk once it is offered (RFC 793) 332 * 2. We limit memory per socket 333 * 334 * For now we use NET2E3's heuristic of offering half the memory 335 * we have handy. All is not as bad as this seems however because 336 * of two things. Firstly we will bin packets even within the window 337 * in order to get the data we are waiting for into the memory limit. 338 * Secondly we bin common duplicate forms at receive time 339 * Better heuristics welcome 340 */ 341
342 inttcp_select_window(structsock *sk)
/* */ 343 { 344 intnew_window = sk->prot->rspace(sk);
345
346 if(sk->window_clamp)
347 new_window=min(sk->window_clamp,new_window);
348 /* 349 * Two things are going on here. First, we don't ever offer a 350 * window less than min(sk->mss, MAX_WINDOW/2). This is the 351 * receiver side of SWS as specified in RFC1122. 352 * Second, we always give them at least the window they 353 * had before, in order to avoid retracting window. This 354 * is technically allowed, but RFC1122 advises against it and 355 * in practice it causes trouble. 356 * 357 * Fixme: This doesn't correctly handle the case where 358 * new_window > sk->window but not by enough to allow for the 359 * shift in sequence space. 360 */ 361 if (new_window < min(sk->mss, MAX_WINDOW/2) || new_window < sk->window)
362 return(sk->window);
363 return(new_window);
364 } 365
366 /* 367 * Find someone to 'accept'. Must be called with 368 * sk->inuse=1 or cli() 369 */ 370
371 staticstructsk_buff *tcp_find_established(structsock *s)
/* */ 372 { 373 structsk_buff *p=skb_peek(&s->receive_queue);
374 if(p==NULL)
375 returnNULL;
376 do 377 { 378 if(p->sk->state == TCP_ESTABLISHED || p->sk->state >= TCP_FIN_WAIT1)
379 returnp;
380 p=p->next;
381 } 382 while(p!=(structsk_buff *)&s->receive_queue);
383 returnNULL;
384 } 385
386 /* 387 * Remove a completed connection and return it. This is used by 388 * tcp_accept() to get connections from the queue. 389 */ 390
391 staticstructsk_buff *tcp_dequeue_established(structsock *s)
/* */ 392 { 393 structsk_buff *skb;
394 unsignedlongflags;
395 save_flags(flags);
396 cli();
397 skb=tcp_find_established(s);
398 if(skb!=NULL)
399 skb_unlink(skb); /* Take it off the queue */ 400 restore_flags(flags);
401 returnskb;
402 } 403
404 /* 405 * This routine closes sockets which have been at least partially 406 * opened, but not yet accepted. Currently it is only called by 407 * tcp_close, and timeout mirrors the value there. 408 */ 409
410 staticvoidtcp_close_pending (structsock *sk)
/* */ 411 { 412 structsk_buff *skb;
413
414 while ((skb = skb_dequeue(&sk->receive_queue)) != NULL)
415 { 416 skb->sk->dead=1;
417 tcp_close(skb->sk, 0);
418 kfree_skb(skb, FREE_READ);
419 } 420 return;
421 } 422
423 /* 424 * Enter the time wait state. 425 */ 426
427 staticvoidtcp_time_wait(structsock *sk)
/* */ 428 { 429 tcp_set_state(sk,TCP_TIME_WAIT);
430 sk->shutdown = SHUTDOWN_MASK;
431 if (!sk->dead)
432 sk->state_change(sk);
433 reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
434 } 435
436 /* 437 * A socket has timed out on its send queue and wants to do a 438 * little retransmitting. Currently this means TCP. 439 */ 440
441 voidtcp_do_retransmit(structsock *sk, intall)
/* */ 442 { 443 structsk_buff * skb;
444 structproto *prot;
445 structdevice *dev;
446 intct=0;
447 structrtable *rt;
448
449 prot = sk->prot;
450 skb = sk->send_head;
451
452 while (skb != NULL)
453 { 454 structtcphdr *th;
455 structiphdr *iph;
456 intsize;
457
458 dev = skb->dev;
459 IS_SKB(skb);
460 skb->when = jiffies;
461
462 /* 463 * Discard the surplus MAC header 464 */ 465
466 skb_pull(skb,((unsignedchar *)skb->ip_hdr)-skb->data);
467
468 /* 469 * In general it's OK just to use the old packet. However we 470 * need to use the current ack and window fields. Urg and 471 * urg_ptr could possibly stand to be updated as well, but we 472 * don't keep the necessary data. That shouldn't be a problem, 473 * if the other end is doing the right thing. Since we're 474 * changing the packet, we have to issue a new IP identifier. 475 */ 476
477 iph = (structiphdr *)skb->data;
478 th = (structtcphdr *)(((char *)iph) + (iph->ihl << 2));
479 size = ntohs(iph->tot_len) - (iph->ihl<<2);
480
481 /* 482 * Note: We ought to check for window limits here but 483 * currently this is done (less efficiently) elsewhere. 484 */ 485
486 iph->id = htons(ip_id_count++);
487 ip_send_check(iph);
488
489 /* 490 * Put a MAC header back on (may cause ARPing) 491 */ 492
493 if(skb->localroute)
494 rt=ip_rt_local(iph->daddr,NULL,NULL);
495 else 496 rt=ip_rt_route(iph->daddr,NULL,NULL);
497
498 if(rt==NULL) /* Deep poo */ 499 { 500 if(skb->sk)
501 { 502 skb->sk->err=ENETUNREACH;
503 skb->sk->error_report(skb->sk);
504 } 505 } 506 else 507 { 508 dev=rt->rt_dev;
509 skb->raddr=rt->rt_gateway;
510 if(skb->raddr==0)
511 skb->raddr=iph->daddr;
512 skb->dev=dev;
513 skb->arp=1;
514 if(dev->hard_header)
515 { 516 if(dev->hard_header(skb, dev, ETH_P_IP, NULL, NULL, skb->len)<0)
517 skb->arp=0;
518 } 519
520 /* 521 * This is not the right way to handle this. We have to 522 * issue an up to date window and ack report with this 523 * retransmit to keep the odd buggy tcp that relies on 524 * the fact BSD does this happy. 525 * We don't however need to recalculate the entire 526 * checksum, so someone wanting a small problem to play 527 * with might like to implement RFC1141/RFC1624 and speed 528 * this up by avoiding a full checksum. 529 */ 530
531 th->ack_seq = ntohl(sk->acked_seq);
532 th->window = ntohs(tcp_select_window(sk));
533 tcp_send_check(th, sk->saddr, sk->daddr, size, sk);
534
535 /* 536 * If the interface is (still) up and running, kick it. 537 */ 538
539 if (dev->flags & IFF_UP)
540 { 541 /* 542 * If the packet is still being sent by the device/protocol 543 * below then don't retransmit. This is both needed, and good - 544 * especially with connected mode AX.25 where it stops resends 545 * occurring of an as yet unsent anyway frame! 546 * We still add up the counts as the round trip time wants 547 * adjusting. 548 */ 549 if (sk && !skb_device_locked(skb))
550 { 551 /* Remove it from any existing driver queue first! */ 552 skb_unlink(skb);
553 /* Now queue it */ 554 ip_statistics.IpOutRequests++;
555 dev_queue_xmit(skb, dev, sk->priority);
556 } 557 } 558 } 559
560 /* 561 * Count retransmissions 562 */ 563
564 ct++;
565 sk->prot->retransmits ++;
566 tcp_statistics.TcpRetransSegs++;
567
568
569 /* 570 * Only one retransmit requested. 571 */ 572
573 if (!all)
574 break;
575
576 /* 577 * This should cut it off before we send too many packets. 578 */ 579
580 if (ct >= sk->cong_window)
581 break;
582 skb = skb->link3;
583 } 584 } 585
586 /* 587 * Reset the retransmission timer 588 */ 589
590 staticvoidreset_xmit_timer(structsock *sk, intwhy, unsignedlongwhen)
/* */ 591 { 592 del_timer(&sk->retransmit_timer);
593 sk->ip_xmit_timeout = why;
594 if((int)when < 0)
595 { 596 when=3;
597 printk("Error: Negative timer in xmit_timer\n");
598 } 599 sk->retransmit_timer.expires=when;
600 add_timer(&sk->retransmit_timer);
601 } 602
603 /* 604 * This is the normal code called for timeouts. It does the retransmission 605 * and then does backoff. tcp_do_retransmit is separated out because 606 * tcp_ack needs to send stuff from the retransmit queue without 607 * initiating a backoff. 608 */ 609
610
611 voidtcp_retransmit_time(structsock *sk, intall)
/* */ 612 { 613 tcp_do_retransmit(sk, all);
614
615 /* 616 * Increase the timeout each time we retransmit. Note that 617 * we do not increase the rtt estimate. rto is initialized 618 * from rtt, but increases here. Jacobson (SIGCOMM 88) suggests 619 * that doubling rto each time is the least we can get away with. 620 * In KA9Q, Karn uses this for the first few times, and then 621 * goes to quadratic. netBSD doubles, but only goes up to *64, 622 * and clamps at 1 to 64 sec afterwards. Note that 120 sec is 623 * defined in the protocol as the maximum possible RTT. I guess 624 * we'll have to use something other than TCP to talk to the 625 * University of Mars. 626 * 627 * PAWS allows us longer timeouts and large windows, so once 628 * implemented ftp to mars will work nicely. We will have to fix 629 * the 120 second clamps though! 630 */ 631
632 sk->retransmits++;
633 sk->prot->retransmits++;
634 sk->backoff++;
635 sk->rto = min(sk->rto << 1, 120*HZ);
636 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
637 } 638
639
640 /* 641 * A timer event has trigger a tcp retransmit timeout. The 642 * socket xmit queue is ready and set up to send. Because 643 * the ack receive code keeps the queue straight we do 644 * nothing clever here. 645 */ 646
647 staticvoidtcp_retransmit(structsock *sk, intall)
/* */ 648 { 649 if (all)
650 { 651 tcp_retransmit_time(sk, all);
652 return;
653 } 654
655 sk->ssthresh = sk->cong_window >> 1; /* remember window where we lost */ 656 /* sk->ssthresh in theory can be zero. I guess that's OK */ 657 sk->cong_count = 0;
658
659 sk->cong_window = 1;
660
661 /* Do the actual retransmit. */ 662 tcp_retransmit_time(sk, all);
663 } 664
665 /* 666 * A write timeout has occurred. Process the after effects. 667 */ 668
669 staticinttcp_write_timeout(structsock *sk)
/* */ 670 { 671 /* 672 * Look for a 'soft' timeout. 673 */ 674 if ((sk->state == TCP_ESTABLISHED && sk->retransmits && !(sk->retransmits & 7))
675 || (sk->state != TCP_ESTABLISHED && sk->retransmits > TCP_RETR1))
676 { 677 /* 678 * Attempt to recover if arp has changed (unlikely!) or 679 * a route has shifted (not supported prior to 1.3). 680 */ 681 arp_destroy (sk->daddr, 0);
682 /*ip_route_check (sk->daddr);*/ 683 } 684
685 /* 686 * Have we tried to SYN too many times (repent repent 8)) 687 */ 688
689 if(sk->retransmits > TCP_SYN_RETRIES && sk->state==TCP_SYN_SENT)
690 { 691 sk->err=ETIMEDOUT;
692 sk->error_report(sk);
693 del_timer(&sk->retransmit_timer);
694 tcp_statistics.TcpAttemptFails++; /* Is this right ??? - FIXME - */ 695 tcp_set_state(sk,TCP_CLOSE);
696 /* Don't FIN, we got nothing back */ 697 release_sock(sk);
698 return 0;
699 } 700 /* 701 * Has it gone just too far ? 702 */ 703 if (sk->retransmits > TCP_RETR2)
704 { 705 sk->err = ETIMEDOUT;
706 sk->error_report(sk);
707 del_timer(&sk->retransmit_timer);
708 /* 709 * Time wait the socket 710 */ 711 if (sk->state == TCP_FIN_WAIT1 || sk->state == TCP_FIN_WAIT2 || sk->state == TCP_CLOSING )
712 { 713 tcp_set_state(sk,TCP_TIME_WAIT);
714 reset_msl_timer (sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
715 } 716 else 717 { 718 /* 719 * Clean up time. 720 */ 721 tcp_set_state(sk, TCP_CLOSE);
722 release_sock(sk);
723 return 0;
724 } 725 } 726 return 1;
727 } 728
729 /* 730 * The TCP retransmit timer. This lacks a few small details. 731 * 732 * 1. An initial rtt timeout on the probe0 should cause what we can 733 * of the first write queue buffer to be split and sent. 734 * 2. On a 'major timeout' as defined by RFC1122 we shouldn't report 735 * ETIMEDOUT if we know an additional 'soft' error caused this. 736 * tcp_err should save a 'soft error' for us. 737 */ 738
739 staticvoidretransmit_timer(unsignedlongdata)
/* */ 740 { 741 structsock *sk = (structsock*)data;
742 intwhy = sk->ip_xmit_timeout;
743
744 /* 745 * only process if socket is not in use 746 */ 747
748 cli();
749 if (sk->inuse || in_bh)
750 { 751 /* Try again in 1 second */ 752 sk->retransmit_timer.expires = HZ;
753 add_timer(&sk->retransmit_timer);
754 sti();
755 return;
756 } 757
758 sk->inuse = 1;
759 sti();
760
761 /* Always see if we need to send an ack. */ 762
763 if (sk->ack_backlog && !sk->zapped)
764 { 765 sk->prot->read_wakeup (sk);
766 if (! sk->dead)
767 sk->data_ready(sk,0);
768 } 769
770 /* Now we need to figure out why the socket was on the timer. */ 771
772 switch (why)
773 { 774 /* Window probing */ 775 caseTIME_PROBE0:
776 tcp_send_probe0(sk);
777 tcp_write_timeout(sk);
778 break;
779 /* Retransmitting */ 780 caseTIME_WRITE:
781 /* It could be we got here because we needed to send an ack. 782 * So we need to check for that. 783 */ 784 { 785 structsk_buff *skb;
786 unsignedlongflags;
787
788 save_flags(flags);
789 cli();
790 skb = sk->send_head;
791 if (!skb)
792 { 793 restore_flags(flags);
794 } 795 else 796 { 797 /* 798 * Kicked by a delayed ack. Reset timer 799 * correctly now 800 */ 801 if (jiffies < skb->when + sk->rto)
802 { 803 reset_xmit_timer (sk, TIME_WRITE, skb->when + sk->rto - jiffies);
804 restore_flags(flags);
805 break;
806 } 807 restore_flags(flags);
808 /* 809 * Retransmission 810 */ 811 sk->prot->retransmit (sk, 0);
812 tcp_write_timeout(sk);
813 } 814 break;
815 } 816 /* Sending Keepalives */ 817 caseTIME_KEEPOPEN:
818 /* 819 * this reset_timer() call is a hack, this is not 820 * how KEEPOPEN is supposed to work. 821 */ 822 reset_xmit_timer (sk, TIME_KEEPOPEN, TCP_TIMEOUT_LEN);
823
824 /* Send something to keep the connection open. */ 825 if (sk->prot->write_wakeup)
826 sk->prot->write_wakeup (sk);
827 sk->retransmits++;
828 sk->prot->retransmits++;
829 tcp_write_timeout(sk);
830 break;
831 default:
832 printk ("rexmit_timer: timer expired - reason unknown\n");
833 break;
834 } 835 release_sock(sk);
836 } 837
838 /* 839 * This routine is called by the ICMP module when it gets some 840 * sort of error condition. If err < 0 then the socket should 841 * be closed and the error returned to the user. If err > 0 842 * it's just the icmp type << 8 | icmp code. After adjustment 843 * header points to the first 8 bytes of the tcp header. We need 844 * to find the appropriate port. 845 */ 846
847 voidtcp_err(interr, unsignedchar *header, unsignedlongdaddr,
/* */ 848 unsignedlongsaddr, structinet_protocol *protocol)
849 { 850 structtcphdr *th;
851 structsock *sk;
852 structiphdr *iph=(structiphdr *)header;
853
854 header+=4*iph->ihl;
855
856
857 th =(structtcphdr *)header;
858 sk = get_sock(&tcp_prot, th->source, daddr, th->dest, saddr);
859
860 if (sk == NULL)
861 return;
862
863 if(err<0)
864 { 865 sk->err = -err;
866 sk->error_report(sk);
867 return;
868 } 869
870 if ((err & 0xff00) == (ICMP_SOURCE_QUENCH << 8))
871 { 872 /* 873 * FIXME: 874 * For now we will just trigger a linear backoff. 875 * The slow start code should cause a real backoff here. 876 */ 877 if (sk->cong_window > 4)
878 sk->cong_window--;
879 return;
880 } 881
882 /* sk->err = icmp_err_convert[err & 0xff].errno; -- moved as TCP should hide non fatals internally (and does) */ 883
884 /* 885 * If we've already connected we will keep trying 886 * until we time out, or the user gives up. 887 */ 888
889 if (icmp_err_convert[err & 0xff].fatal || sk->state == TCP_SYN_SENT)
890 { 891 if (sk->state == TCP_SYN_SENT)
892 { 893 tcp_statistics.TcpAttemptFails++;
894 tcp_set_state(sk,TCP_CLOSE);
895 sk->error_report(sk); /* Wake people up to see the error (see connect in sock.c) */ 896 } 897 sk->err = icmp_err_convert[err & 0xff].errno;
898 } 899 return;
900 } 901
902
903 /* 904 * Walk down the receive queue counting readable data until we hit the end or we find a gap 905 * in the received data queue (ie a frame missing that needs sending to us). Not 906 * sorting using two queues as data arrives makes life so much harder. 907 */ 908
909 staticinttcp_readable(structsock *sk)
/* */ 910 { 911 unsignedlongcounted;
912 unsignedlongamount;
913 structsk_buff *skb;
914 intsum;
915 unsignedlongflags;
916
917 if(sk && sk->debug)
918 printk("tcp_readable: %p - ",sk);
919
920 save_flags(flags);
921 cli();
922 if (sk == NULL || (skb = skb_peek(&sk->receive_queue)) == NULL)
923 { 924 restore_flags(flags);
925 if(sk && sk->debug)
926 printk("empty\n");
927 return(0);
928 } 929
930 counted = sk->copied_seq; /* Where we are at the moment */ 931 amount = 0;
932
933 /* 934 * Do until a push or until we are out of data. 935 */ 936
937 do 938 { 939 if (before(counted, skb->h.th->seq)) /* Found a hole so stops here */ 940 break;
941 sum = skb->len -(counted - skb->h.th->seq); /* Length - header but start from where we are up to (avoid overlaps) */ 942 if (skb->h.th->syn)
943 sum++;
944 if (sum > 0)
945 {/* Add it up, move on */ 946 amount += sum;
947 if (skb->h.th->syn)
948 amount--;
949 counted += sum;
950 } 951 /* 952 * Don't count urg data ... but do it in the right place! 953 * Consider: "old_data (ptr is here) URG PUSH data" 954 * The old code would stop at the first push because 955 * it counted the urg (amount==1) and then does amount-- 956 * *after* the loop. This means tcp_readable() always 957 * returned zero if any URG PUSH was in the queue, even 958 * though there was normal data available. If we subtract 959 * the urg data right here, we even get it to work for more 960 * than one URG PUSH skb without normal data. 961 * This means that select() finally works now with urg data 962 * in the queue. Note that rlogin was never affected 963 * because it doesn't use select(); it uses two processes 964 * and a blocking read(). And the queue scan in tcp_read() 965 * was correct. Mike <pall@rz.uni-karlsruhe.de> 966 */ 967 if (skb->h.th->urg)
968 amount--; /* don't count urg data */ 969 if (amount && skb->h.th->psh) break;
970 skb = skb->next;
971 } 972 while(skb != (structsk_buff *)&sk->receive_queue);
973
974 restore_flags(flags);
975 if(sk->debug)
976 printk("got %lu bytes.\n",amount);
977 return(amount);
978 } 979
980 /* 981 * LISTEN is a special case for select.. 982 */ 983 staticinttcp_listen_select(structsock *sk, intsel_type, select_table *wait)
/* */ 984 { 985 if (sel_type == SEL_IN) { 986 intretval;
987
988 sk->inuse = 1;
989 retval = (tcp_find_established(sk) != NULL);
990 release_sock(sk);
991 if (!retval)
992 select_wait(&master_select_wakeup,wait);
993 returnretval;
994 } 995 return 0;
996 } 997
998
999 /*1000 * Wait for a TCP event.1001 *1002 * Note that we don't need to set "sk->inuse", as the upper select layers1003 * take care of normal races (between the test and the event) and we don't1004 * go look at any of the socket buffers directly.1005 */1006 staticinttcp_select(structsock *sk, intsel_type, select_table *wait)
/* */1007 {1008 if (sk->state == TCP_LISTEN)
1009 returntcp_listen_select(sk, sel_type, wait);
1010
1011 switch(sel_type) {1012 caseSEL_IN:
1013 if (sk->err)
1014 return 1;
1015 if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
1016 break;
1017
1018 if (sk->shutdown & RCV_SHUTDOWN)
1019 return 1;
1020
1021 if (sk->acked_seq == sk->copied_seq)
1022 break;
1023
1024 if (sk->urg_seq != sk->copied_seq ||
1025 sk->acked_seq != sk->copied_seq+1 ||
1026 sk->urginline || !sk->urg_data)
1027 return 1;
1028 break;
1029
1030 caseSEL_OUT:
1031 if (sk->err)
1032 return 1;
1033 if (sk->shutdown & SEND_SHUTDOWN)
1034 return 0;
1035 if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
1036 break;
1037 /*1038 * This is now right thanks to a small fix1039 * by Matt Dillon.1040 */1041
1042 if (sk->prot->wspace(sk) < sk->mtu+128+sk->prot->max_header)
1043 break;
1044 return 1;
1045
1046 caseSEL_EX:
1047 if (sk->urg_data)
1048 return 1;
1049 break;
1050 }1051 select_wait(sk->sleep, wait);
1052 return 0;
1053 }1054
1055 inttcp_ioctl(structsock *sk, intcmd, unsignedlongarg)
/* */1056 {1057 interr;
1058 switch(cmd)
1059 {1060
1061 caseTIOCINQ:
1062 #ifdef FIXME /* FIXME: */1063 caseFIONREAD:
1064 #endif1065 {1066 unsignedlongamount;
1067
1068 if (sk->state == TCP_LISTEN)
1069 return(-EINVAL);
1070
1071 sk->inuse = 1;
1072 amount = tcp_readable(sk);
1073 release_sock(sk);
1074 err=verify_area(VERIFY_WRITE,(void *)arg, sizeof(int));
1075 if(err)
1076 returnerr;
1077 put_user(amount, (int *)arg);
1078 return(0);
1079 }1080 caseSIOCATMARK:
1081 {1082 intansw = sk->urg_data && sk->urg_seq == sk->copied_seq;
1083
1084 err = verify_area(VERIFY_WRITE,(void *) arg, sizeof(int));
1085 if (err)
1086 returnerr;
1087 put_user(answ,(int *) arg);
1088 return(0);
1089 }1090 caseTIOCOUTQ:
1091 {1092 unsignedlongamount;
1093
1094 if (sk->state == TCP_LISTEN) return(-EINVAL);
1095 amount = sk->prot->wspace(sk);
1096 err=verify_area(VERIFY_WRITE,(void *)arg, sizeof(int));
1097 if(err)
1098 returnerr;
1099 put_user(amount, (int *)arg);
1100 return(0);
1101 }1102 default:
1103 return(-EINVAL);
1104 }1105 }1106
1107
1108 /*1109 * This routine computes a TCP checksum. 1110 *1111 * Modified January 1995 from a go-faster DOS routine by1112 * Jorge Cwik <jorge@laser.satlink.net>1113 */1114
1115 unsignedshorttcp_check(structtcphdr *th, intlen,
/* */1116 unsignedlongsaddr, unsignedlongdaddr, unsignedlongbase)
1117 {1118 returncsum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1119 }1120
1121
1122
1123 voidtcp_send_check(structtcphdr *th, unsignedlongsaddr,
/* */1124 unsignedlongdaddr, intlen, structsock *sk)
1125 {1126 th->check = 0;
1127 th->check = tcp_check(th, len, saddr, daddr,
1128 csum_partial((char *)th,len,0));
1129 return;
1130 }1131
1132 /*1133 * This is the main buffer sending routine. We queue the buffer1134 * having checked it is sane seeming.1135 */1136
1137 staticvoidtcp_send_skb(structsock *sk, structsk_buff *skb)
/* */1138 {1139 intsize;
1140 structtcphdr * th = skb->h.th;
1141
1142 /*1143 * length of packet (not counting length of pre-tcp headers) 1144 */1145
1146 size = skb->len - ((unsignedchar *) th - skb->data);
1147
1148 /*1149 * Sanity check it.. 1150 */1151
1152 if (size < sizeof(structtcphdr) || size > skb->len)
1153 {1154 printk("tcp_send_skb: bad skb (skb = %p, data = %p, th = %p, len = %lu)\n",
1155 skb, skb->data, th, skb->len);
1156 kfree_skb(skb, FREE_WRITE);
1157 return;
1158 }1159
1160 /*1161 * If we have queued a header size packet.. (these crash a few1162 * tcp stacks if ack is not set)1163 */1164
1165 if (size == sizeof(structtcphdr))
1166 {1167 /* If it's got a syn or fin it's notionally included in the size..*/1168 if(!th->syn && !th->fin)
1169 {1170 printk("tcp_send_skb: attempt to queue a bogon.\n");
1171 kfree_skb(skb,FREE_WRITE);
1172 return;
1173 }1174 }1175
1176 /*1177 * Actual processing.1178 */1179
1180 tcp_statistics.TcpOutSegs++;
1181 skb->h.seq = ntohl(th->seq) + size - 4*th->doff;
1182
1183 /*1184 * We must queue if1185 *1186 * a) The right edge of this frame exceeds the window1187 * b) We are retransmitting (Nagle's rule)1188 * c) We have too many packets 'in flight'1189 */1190
1191 if (after(skb->h.seq, sk->window_seq) ||
1192 (sk->retransmits && sk->ip_xmit_timeout == TIME_WRITE) ||
1193 sk->packets_out >= sk->cong_window)
1194 {1195 /* checksum will be supplied by tcp_write_xmit. So1196 * we shouldn't need to set it at all. I'm being paranoid */1197 th->check = 0;
1198 if (skb->next != NULL)
1199 {1200 printk("tcp_send_partial: next != NULL\n");
1201 skb_unlink(skb);
1202 }1203 skb_queue_tail(&sk->write_queue, skb);
1204
1205 /*1206 * If we don't fit we have to start the zero window1207 * probes. This is broken - we really need to do a partial1208 * send _first_ (This is what causes the Cisco and PC/TCP1209 * grief).1210 */1211
1212 if (before(sk->window_seq, sk->write_queue.next->h.seq) &&
1213 sk->send_head == NULL && sk->ack_backlog == 0)
1214 reset_xmit_timer(sk, TIME_PROBE0, sk->rto);
1215 }1216 else1217 {1218 /*1219 * This is going straight out1220 */1221
1222 th->ack_seq = ntohl(sk->acked_seq);
1223 th->window = ntohs(tcp_select_window(sk));
1224
1225 tcp_send_check(th, sk->saddr, sk->daddr, size, sk);
1226
1227 sk->sent_seq = sk->write_seq;
1228
1229 /*1230 * This is mad. The tcp retransmit queue is put together1231 * by the ip layer. This causes half the problems with1232 * unroutable FIN's and other things.1233 */1234
1235 sk->prot->queue_xmit(sk, skb->dev, skb, 0);
1236
1237 /*1238 * Set for next retransmit based on expected ACK time.1239 * FIXME: We set this every time which means our 1240 * retransmits are really about a window behind.1241 */1242
1243 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
1244 }1245 }1246
1247 /*1248 * Locking problems lead us to a messy situation where we can have1249 * multiple partially complete buffers queued up. This is really bad1250 * as we don't want to be sending partial buffers. Fix this with1251 * a semaphore or similar to lock tcp_write per socket.1252 *1253 * These routines are pretty self descriptive.1254 */1255
1256 structsk_buff * tcp_dequeue_partial(structsock * sk)
/* */1257 {1258 structsk_buff * skb;
1259 unsignedlongflags;
1260
1261 save_flags(flags);
1262 cli();
1263 skb = sk->partial;
1264 if (skb) {1265 sk->partial = NULL;
1266 del_timer(&sk->partial_timer);
1267 }1268 restore_flags(flags);
1269 returnskb;
1270 }1271
1272 /*1273 * Empty the partial queue1274 */1275
1276 staticvoidtcp_send_partial(structsock *sk)
/* */1277 {1278 structsk_buff *skb;
1279
1280 if (sk == NULL)
1281 return;
1282 while ((skb = tcp_dequeue_partial(sk)) != NULL)
1283 tcp_send_skb(sk, skb);
1284 }1285
1286 /*1287 * Queue a partial frame1288 */1289
1290 voidtcp_enqueue_partial(structsk_buff * skb, structsock * sk)
/* */1291 {1292 structsk_buff * tmp;
1293 unsignedlongflags;
1294
1295 save_flags(flags);
1296 cli();
1297 tmp = sk->partial;
1298 if (tmp)
1299 del_timer(&sk->partial_timer);
1300 sk->partial = skb;
1301 init_timer(&sk->partial_timer);
1302 /*1303 * Wait up to 1 second for the buffer to fill.1304 */1305 sk->partial_timer.expires = HZ;
1306 sk->partial_timer.function = (void (*)(unsignedlong)) tcp_send_partial;
1307 sk->partial_timer.data = (unsignedlong) sk;
1308 add_timer(&sk->partial_timer);
1309 restore_flags(flags);
1310 if (tmp)
1311 tcp_send_skb(sk, tmp);
1312 }1313
1314
1315 /*1316 * This routine sends an ack and also updates the window. 1317 */1318
1319 staticvoidtcp_send_ack(u32sequence, u32ack,
/* */1320 structsock *sk,
1321 structtcphdr *th, unsignedlongdaddr)
1322 {1323 structsk_buff *buff;
1324 structtcphdr *t1;
1325 structdevice *dev = NULL;
1326 inttmp;
1327
1328 if(sk->zapped)
1329 return; /* We have been reset, we may not send again */1330
1331 /*1332 * We need to grab some memory, and put together an ack,1333 * and then put it into the queue to be sent.1334 */1335
1336 buff = sk->prot->wmalloc(sk, MAX_ACK_SIZE, 1, GFP_ATOMIC);
1337 if (buff == NULL)
1338 {1339 /* 1340 * Force it to send an ack. We don't have to do this1341 * (ACK is unreliable) but it's much better use of 1342 * bandwidth on slow links to send a spare ack than1343 * resend packets. 1344 */1345
1346 sk->ack_backlog++;
1347 if (sk->ip_xmit_timeout != TIME_WRITE && tcp_connected(sk->state))
1348 {1349 reset_xmit_timer(sk, TIME_WRITE, HZ);
1350 }1351 return;
1352 }1353
1354 /*1355 * Assemble a suitable TCP frame1356 */1357
1358 buff->sk = sk;
1359 buff->localroute = sk->localroute;
1360
1361 /* 1362 * Put in the IP header and routing stuff. 1363 */1364
1365 tmp = sk->prot->build_header(buff, sk->saddr, daddr, &dev,
1366 IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl);
1367 if (tmp < 0)
1368 {1369 buff->free = 1;
1370 sk->prot->wfree(sk, buff);
1371 return;
1372 }1373 t1 =(structtcphdr *)skb_put(buff,sizeof(structtcphdr));
1374
1375 memcpy(t1, th, sizeof(*t1));
1376
1377 /*1378 * Swap the send and the receive. 1379 */1380
1381 t1->dest = th->source;
1382 t1->source = th->dest;
1383 t1->seq = ntohl(sequence);
1384 t1->ack = 1;
1385 sk->window = tcp_select_window(sk);
1386 t1->window = ntohs(sk->window);
1387 t1->res1 = 0;
1388 t1->res2 = 0;
1389 t1->rst = 0;
1390 t1->urg = 0;
1391 t1->syn = 0;
1392 t1->psh = 0;
1393 t1->fin = 0;
1394
1395 /*1396 * If we have nothing queued for transmit and the transmit timer1397 * is on we are just doing an ACK timeout and need to switch1398 * to a keepalive.1399 */1400
1401 if (ack == sk->acked_seq)
1402 {1403 sk->ack_backlog = 0;
1404 sk->bytes_rcv = 0;
1405 sk->ack_timed = 0;
1406 if (sk->send_head == NULL && skb_peek(&sk->write_queue) == NULL1407 && sk->ip_xmit_timeout == TIME_WRITE)
1408 {1409 if(sk->keepopen) {1410 reset_xmit_timer(sk,TIME_KEEPOPEN,TCP_TIMEOUT_LEN);
1411 }else{1412 delete_timer(sk);
1413 }1414 }1415 }1416
1417 /*1418 * Fill in the packet and send it1419 */1420
1421 t1->ack_seq = ntohl(ack);
1422 t1->doff = sizeof(*t1)/4;
1423 tcp_send_check(t1, sk->saddr, daddr, sizeof(*t1), sk);
1424 if (sk->debug)
1425 printk("\rtcp_ack: seq %x ack %x\n", sequence, ack);
1426 tcp_statistics.TcpOutSegs++;
1427 sk->prot->queue_xmit(sk, dev, buff, 1);
1428 }1429
1430
1431 /* 1432 * This routine builds a generic TCP header. 1433 */1434
1435 extern__inlineinttcp_build_header(structtcphdr *th, structsock *sk, intpush)
/* */1436 {1437
1438 memcpy(th,(void *) &(sk->dummy_th), sizeof(*th));
1439 th->seq = htonl(sk->write_seq);
1440 th->psh =(push == 0) ? 1 : 0;
1441 th->doff = sizeof(*th)/4;
1442 th->ack = 1;
1443 th->fin = 0;
1444 sk->ack_backlog = 0;
1445 sk->bytes_rcv = 0;
1446 sk->ack_timed = 0;
1447 th->ack_seq = htonl(sk->acked_seq);
1448 sk->window = tcp_select_window(sk);
1449 th->window = htons(sk->window);
1450
1451 return(sizeof(*th));
1452 }1453
1454 /*1455 * This routine copies from a user buffer into a socket,1456 * and starts the transmit system.1457 */1458
1459 staticinttcp_write(structsock *sk, unsignedchar *from,
/* */1460 intlen, intnonblock, unsignedflags)
1461 {1462 intcopied = 0;
1463 intcopy;
1464 inttmp;
1465 structsk_buff *skb;
1466 structsk_buff *send_tmp;
1467 structproto *prot;
1468 structdevice *dev = NULL;
1469
1470 sk->inuse=1;
1471 prot = sk->prot;
1472 while(len > 0)
1473 {1474 if (sk->err)
1475 {/* Stop on an error */1476 release_sock(sk);
1477 if (copied)
1478 return(copied);
1479 tmp = -sk->err;
1480 sk->err = 0;
1481 return(tmp);
1482 }1483
1484 /*1485 * First thing we do is make sure that we are established. 1486 */1487
1488 if (sk->shutdown & SEND_SHUTDOWN)
1489 {1490 release_sock(sk);
1491 sk->err = EPIPE;
1492 if (copied)
1493 return(copied);
1494 sk->err = 0;
1495 return(-EPIPE);
1496 }1497
1498 /* 1499 * Wait for a connection to finish.1500 */1501
1502 while(sk->state != TCP_ESTABLISHED && sk->state != TCP_CLOSE_WAIT)
1503 {1504 if (sk->err)
1505 {1506 release_sock(sk);
1507 if (copied)
1508 return(copied);
1509 tmp = -sk->err;
1510 sk->err = 0;
1511 return(tmp);
1512 }1513
1514 if (sk->state != TCP_SYN_SENT && sk->state != TCP_SYN_RECV)
1515 {1516 release_sock(sk);
1517 if (copied)
1518 return(copied);
1519
1520 if (sk->err)
1521 {1522 tmp = -sk->err;
1523 sk->err = 0;
1524 return(tmp);
1525 }1526
1527 if (sk->keepopen)
1528 {1529 send_sig(SIGPIPE, current, 0);
1530 }1531 return(-EPIPE);
1532 }1533
1534 if (nonblock || copied)
1535 {1536 release_sock(sk);
1537 if (copied)
1538 return(copied);
1539 return(-EAGAIN);
1540 }1541
1542 release_sock(sk);
1543 cli();
1544
1545 if (sk->state != TCP_ESTABLISHED &&
1546 sk->state != TCP_CLOSE_WAIT && sk->err == 0)
1547 {1548 interruptible_sleep_on(sk->sleep);
1549 if (current->signal & ~current->blocked)
1550 {1551 sti();
1552 if (copied)
1553 return(copied);
1554 return(-ERESTARTSYS);
1555 }1556 }1557 sk->inuse = 1;
1558 sti();
1559 }1560
1561 /*1562 * The following code can result in copy <= if sk->mss is ever1563 * decreased. It shouldn't be. sk->mss is min(sk->mtu, sk->max_window).1564 * sk->mtu is constant once SYN processing is finished. I.e. we1565 * had better not get here until we've seen his SYN and at least one1566 * valid ack. (The SYN sets sk->mtu and the ack sets sk->max_window.)1567 * But ESTABLISHED should guarantee that. sk->max_window is by definition1568 * non-decreasing. Note that any ioctl to set user_mss must be done1569 * before the exchange of SYN's. If the initial ack from the other1570 * end has a window of 0, max_window and thus mss will both be 0.1571 */1572
1573 /* 1574 * Now we need to check if we have a half built packet. 1575 */1576
1577 if ((skb = tcp_dequeue_partial(sk)) != NULL)
1578 {1579 inthdrlen;
1580
1581 /* IP header + TCP header */1582 hdrlen = ((unsignedlong)skb->h.th - (unsignedlong)skb->data)
1583 + sizeof(structtcphdr);
1584
1585 /* Add more stuff to the end of skb->len */1586 if (!(flags & MSG_OOB))
1587 {1588 copy = min(sk->mss - (skb->len - hdrlen), len);
1589 /* FIXME: this is really a bug. */1590 if (copy <= 0)
1591 {1592 printk("TCP: **bug**: \"copy\" <= 0!!\n");
1593 copy = 0;
1594 }1595
1596 memcpy_fromfs(skb_put(skb,copy), from, copy);
1597 from += copy;
1598 copied += copy;
1599 len -= copy;
1600 sk->write_seq += copy;
1601 }1602 if ((skb->len - hdrlen) >= sk->mss ||
1603 (flags & MSG_OOB) || !sk->packets_out)
1604 tcp_send_skb(sk, skb);
1605 else1606 tcp_enqueue_partial(skb, sk);
1607 continue;
1608 }1609
1610 /*1611 * We also need to worry about the window.1612 * If window < 1/2 the maximum window we've seen from this1613 * host, don't use it. This is sender side1614 * silly window prevention, as specified in RFC1122.1615 * (Note that this is different than earlier versions of1616 * SWS prevention, e.g. RFC813.). What we actually do is 1617 * use the whole MSS. Since the results in the right1618 * edge of the packet being outside the window, it will1619 * be queued for later rather than sent.1620 */1621
1622 copy = sk->window_seq - sk->write_seq;
1623 if (copy <= 0 || copy < (sk->max_window >> 1) || copy > sk->mss)
1624 copy = sk->mss;
1625 if (copy > len)
1626 copy = len;
1627
1628 /*1629 * We should really check the window here also. 1630 */1631
1632 send_tmp = NULL;
1633 if (copy < sk->mss && !(flags & MSG_OOB))
1634 {1635 /*1636 * We will release the socket in case we sleep here. 1637 */1638 release_sock(sk);
1639 /*1640 * NB: following must be mtu, because mss can be increased.1641 * mss is always <= mtu 1642 */1643 skb = prot->wmalloc(sk, sk->mtu + 128 + prot->max_header + 15, 0, GFP_KERNEL);
1644 sk->inuse = 1;
1645 send_tmp = skb;
1646 }1647 else1648 {1649 /*1650 * We will release the socket in case we sleep here. 1651 */1652 release_sock(sk);
1653 skb = prot->wmalloc(sk, copy + prot->max_header + 15 , 0, GFP_KERNEL);
1654 sk->inuse = 1;
1655 }1656
1657 /*1658 * If we didn't get any memory, we need to sleep. 1659 */1660
1661 if (skb == NULL)
1662 {1663 sk->socket->flags |= SO_NOSPACE;
1664 if (nonblock)
1665 {1666 release_sock(sk);
1667 if (copied)
1668 return(copied);
1669 return(-EAGAIN);
1670 }1671
1672 /*1673 * FIXME: here is another race condition. 1674 */1675
1676 tmp = sk->wmem_alloc;
1677 release_sock(sk);
1678 cli();
1679 /*1680 * Again we will try to avoid it. 1681 */1682 if (tmp <= sk->wmem_alloc &&
1683 (sk->state == TCP_ESTABLISHED||sk->state == TCP_CLOSE_WAIT)
1684 && sk->err == 0)
1685 {1686 sk->socket->flags &= ~SO_NOSPACE;
1687 interruptible_sleep_on(sk->sleep);
1688 if (current->signal & ~current->blocked)
1689 {1690 sti();
1691 if (copied)
1692 return(copied);
1693 return(-ERESTARTSYS);
1694 }1695 }1696 sk->inuse = 1;
1697 sti();
1698 continue;
1699 }1700
1701 skb->sk = sk;
1702 skb->free = 0;
1703 skb->localroute = sk->localroute|(flags&MSG_DONTROUTE);
1704
1705 /*1706 * FIXME: we need to optimize this.1707 * Perhaps some hints here would be good.1708 */1709
1710 tmp = prot->build_header(skb, sk->saddr, sk->daddr, &dev,
1711 IPPROTO_TCP, sk->opt, skb->truesize,sk->ip_tos,sk->ip_ttl);
1712 if (tmp < 0 )
1713 {1714 prot->wfree(sk, skb);
1715 release_sock(sk);
1716 if (copied)
1717 return(copied);
1718 return(tmp);
1719 }1720 skb->dev = dev;
1721 skb->h.th =(structtcphdr *)skb_put(skb,sizeof(structtcphdr));
1722 tmp = tcp_build_header(skb->h.th, sk, len-copy);
1723 if (tmp < 0)
1724 {1725 prot->wfree(sk, skb);
1726 release_sock(sk);
1727 if (copied)
1728 return(copied);
1729 return(tmp);
1730 }1731
1732 if (flags & MSG_OOB)
1733 {1734 skb->h.th->urg = 1;
1735 skb->h.th->urg_ptr = ntohs(copy);
1736 }1737
1738 memcpy_fromfs(skb_put(skb,copy), from, copy);
1739
1740 from += copy;
1741 copied += copy;
1742 len -= copy;
1743 skb->free = 0;
1744 sk->write_seq += copy;
1745
1746 if (send_tmp != NULL && sk->packets_out)
1747 {1748 tcp_enqueue_partial(send_tmp, sk);
1749 continue;
1750 }1751 tcp_send_skb(sk, skb);
1752 }1753 sk->err = 0;
1754
1755 /*1756 * Nagle's rule. Turn Nagle off with TCP_NODELAY for highly1757 * interactive fast network servers. It's meant to be on and1758 * it really improves the throughput though not the echo time1759 * on my slow slip link - Alan1760 */1761
1762 /*1763 * Avoid possible race on send_tmp - c/o Johannes Stille 1764 */1765
1766 if(sk->partial && ((!sk->packets_out)
1767 /* If not nagling we can send on the before case too.. */1768 || (sk->nonagle && before(sk->write_seq , sk->window_seq))
1769 ))
1770 tcp_send_partial(sk);
1771
1772 release_sock(sk);
1773 return(copied);
1774 }1775
1776 /*1777 * This is just a wrapper. 1778 */1779
1780 staticinttcp_sendto(structsock *sk, unsignedchar *from,
/* */1781 intlen, intnonblock, unsignedflags,
1782 structsockaddr_in *addr, intaddr_len)
1783 {1784 if (flags & ~(MSG_OOB|MSG_DONTROUTE))
1785 return -EINVAL;
1786 if (sk->state == TCP_CLOSE)
1787 return -ENOTCONN;
1788 if (addr_len < sizeof(*addr))
1789 return -EINVAL;
1790 if (addr->sin_family && addr->sin_family != AF_INET)
1791 return -EINVAL;
1792 if (addr->sin_port != sk->dummy_th.dest)
1793 return -EISCONN;
1794 if (addr->sin_addr.s_addr != sk->daddr)
1795 return -EISCONN;
1796 returntcp_write(sk, from, len, nonblock, flags);
1797 }1798
1799
1800 /*1801 * Send an ack if one is backlogged at this point. Ought to merge1802 * this with tcp_send_ack().1803 */1804
1805 staticvoidtcp_read_wakeup(structsock *sk)
/* */1806 {1807 inttmp;
1808 structdevice *dev = NULL;
1809 structtcphdr *t1;
1810 structsk_buff *buff;
1811
1812 if (!sk->ack_backlog)
1813 return;
1814
1815 /*1816 * If we're closed, don't send an ack, or we'll get a RST1817 * from the closed destination.1818 */1819 if ((sk->state == TCP_CLOSE) || (sk->state == TCP_TIME_WAIT))
1820 return;
1821
1822 /*1823 * FIXME: we need to put code here to prevent this routine from1824 * being called. Being called once in a while is ok, so only check1825 * if this is the second time in a row.1826 */1827
1828 /*1829 * We need to grab some memory, and put together an ack,1830 * and then put it into the queue to be sent.1831 */1832
1833 buff = sk->prot->wmalloc(sk,MAX_ACK_SIZE,1, GFP_ATOMIC);
1834 if (buff == NULL)
1835 {1836 /* Try again real soon. */1837 reset_xmit_timer(sk, TIME_WRITE, HZ);
1838 return;
1839 }1840
1841 buff->sk = sk;
1842 buff->localroute = sk->localroute;
1843
1844 /*1845 * Put in the IP header and routing stuff. 1846 */1847
1848 tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
1849 IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl);
1850 if (tmp < 0)
1851 {1852 buff->free = 1;
1853 sk->prot->wfree(sk, buff);
1854 return;
1855 }1856
1857 t1 =(structtcphdr *)skb_put(buff,sizeof(structtcphdr));
1858
1859 memcpy(t1,(void *) &sk->dummy_th, sizeof(*t1));
1860 t1->seq = htonl(sk->sent_seq);
1861 t1->ack = 1;
1862 t1->res1 = 0;
1863 t1->res2 = 0;
1864 t1->rst = 0;
1865 t1->urg = 0;
1866 t1->syn = 0;
1867 t1->psh = 0;
1868 sk->ack_backlog = 0;
1869 sk->bytes_rcv = 0;
1870 sk->window = tcp_select_window(sk);
1871 t1->window = ntohs(sk->window);
1872 t1->ack_seq = ntohl(sk->acked_seq);
1873 t1->doff = sizeof(*t1)/4;
1874 tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), sk);
1875 sk->prot->queue_xmit(sk, dev, buff, 1);
1876 tcp_statistics.TcpOutSegs++;
1877 }1878
1879
1880 /*1881 * FIXME:1882 * This routine frees used buffers.1883 * It should consider sending an ACK to let the1884 * other end know we now have a bigger window.1885 */1886
1887 staticvoidcleanup_rbuf(structsock *sk)
/* */1888 {1889 unsignedlongflags;
1890 unsignedlongleft;
1891 structsk_buff *skb;
1892 unsignedlongrspace;
1893
1894 if(sk->debug)
1895 printk("cleaning rbuf for sk=%p\n", sk);
1896
1897 save_flags(flags);
1898 cli();
1899
1900 left = sk->prot->rspace(sk);
1901
1902 /*1903 * We have to loop through all the buffer headers,1904 * and try to free up all the space we can.1905 */1906
1907 while((skb=skb_peek(&sk->receive_queue)) != NULL)
1908 {1909 if (!skb->used || skb->users)
1910 break;
1911 skb_unlink(skb);
1912 skb->sk = sk;
1913 kfree_skb(skb, FREE_READ);
1914 }1915
1916 restore_flags(flags);
1917
1918 /*1919 * FIXME:1920 * At this point we should send an ack if the difference1921 * in the window, and the amount of space is bigger than1922 * TCP_WINDOW_DIFF.1923 */1924
1925 if(sk->debug)
1926 printk("sk->rspace = %lu, was %lu\n", sk->prot->rspace(sk),
1927 left);
1928 if ((rspace=sk->prot->rspace(sk)) != left)
1929 {1930 /*1931 * This area has caused the most trouble. The current strategy1932 * is to simply do nothing if the other end has room to send at1933 * least 3 full packets, because the ack from those will auto-1934 * matically update the window. If the other end doesn't think1935 * we have much space left, but we have room for at least 1 more1936 * complete packet than it thinks we do, we will send an ack1937 * immediately. Otherwise we will wait up to .5 seconds in case1938 * the user reads some more.1939 */1940 sk->ack_backlog++;
1941 /*1942 * It's unclear whether to use sk->mtu or sk->mss here. They differ only1943 * if the other end is offering a window smaller than the agreed on MSS1944 * (called sk->mtu here). In theory there's no connection between send1945 * and receive, and so no reason to think that they're going to send1946 * small packets. For the moment I'm using the hack of reducing the mss1947 * only on the send side, so I'm putting mtu here.1948 */1949
1950 if (rspace > (sk->window - sk->bytes_rcv + sk->mtu))
1951 {1952 /* Send an ack right now. */1953 tcp_read_wakeup(sk);
1954 }1955 else1956 {1957 /* Force it to send an ack soon. */1958 intwas_active = del_timer(&sk->retransmit_timer);
1959 if (!was_active || TCP_ACK_TIME < sk->timer.expires)
1960 {1961 reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
1962 }1963 else1964 add_timer(&sk->retransmit_timer);
1965 }1966 }1967 }1968
1969
1970 /*1971 * Handle reading urgent data. BSD has very simple semantics for1972 * this, no blocking and very strange errors 8)1973 */1974
1975 staticinttcp_read_urg(structsock * sk, intnonblock,
/* */1976 unsignedchar *to, intlen, unsignedflags)
1977 {1978 /*1979 * No URG data to read1980 */1981 if (sk->urginline || !sk->urg_data || sk->urg_data == URG_READ)
1982 return -EINVAL; /* Yes this is right ! */1983
1984 if (sk->err)
1985 {1986 inttmp = -sk->err;
1987 sk->err = 0;
1988 returntmp;
1989 }1990
1991 if (sk->state == TCP_CLOSE || sk->done)
1992 {1993 if (!sk->done) {1994 sk->done = 1;
1995 return 0;
1996 }1997 return -ENOTCONN;
1998 }1999
2000 if (sk->shutdown & RCV_SHUTDOWN)
2001 {2002 sk->done = 1;
2003 return 0;
2004 }2005 sk->inuse = 1;
2006 if (sk->urg_data & URG_VALID)
2007 {2008 charc = sk->urg_data;
2009 if (!(flags & MSG_PEEK))
2010 sk->urg_data = URG_READ;
2011 put_fs_byte(c, to);
2012 release_sock(sk);
2013 return 1;
2014 }2015 release_sock(sk);
2016
2017 /*2018 * Fixed the recv(..., MSG_OOB) behaviour. BSD docs and2019 * the available implementations agree in this case:2020 * this call should never block, independent of the2021 * blocking state of the socket.2022 * Mike <pall@rz.uni-karlsruhe.de>2023 */2024 return -EAGAIN;
2025 }2026
2027
2028 /*2029 * This routine copies from a sock struct into the user buffer. 2030 */2031
2032 staticinttcp_read(structsock *sk, unsignedchar *to,
/* */2033 intlen, intnonblock, unsignedflags)
2034 {2035 structwait_queuewait = {current, NULL};
2036 intcopied = 0;
2037 u32peek_seq;
2038 volatileu32 *seq; /* So gcc doesn't overoptimise */2039 unsignedlongused;
2040
2041 /* 2042 * This error should be checked. 2043 */2044
2045 if (sk->state == TCP_LISTEN)
2046 return -ENOTCONN;
2047
2048 /*2049 * Urgent data needs to be handled specially. 2050 */2051
2052 if (flags & MSG_OOB)
2053 returntcp_read_urg(sk, nonblock, to, len, flags);
2054
2055 /*2056 * Copying sequence to update. This is volatile to handle2057 * the multi-reader case neatly (memcpy_to/fromfs might be 2058 * inline and thus not flush cached variables otherwise).2059 */2060
2061 peek_seq = sk->copied_seq;
2062 seq = &sk->copied_seq;
2063 if (flags & MSG_PEEK)
2064 seq = &peek_seq;
2065
2066 add_wait_queue(sk->sleep, &wait);
2067 sk->inuse = 1;
2068 while (len > 0)
2069 {2070 structsk_buff * skb;
2071 u32offset;
2072
2073 /*2074 * Are we at urgent data? Stop if we have read anything.2075 */2076
2077 if (copied && sk->urg_data && sk->urg_seq == *seq)
2078 break;
2079
2080 /*2081 * Next get a buffer.2082 */2083
2084 current->state = TASK_INTERRUPTIBLE;
2085
2086 skb = skb_peek(&sk->receive_queue);
2087 do2088 {2089 if (!skb)
2090 break;
2091 if (before(*seq, skb->h.th->seq))
2092 break;
2093 offset = *seq - skb->h.th->seq;
2094 if (skb->h.th->syn)
2095 offset--;
2096 if (offset < skb->len)
2097 gotofound_ok_skb;
2098 if (skb->h.th->fin)
2099 gotofound_fin_ok;
2100 if (!(flags & MSG_PEEK))
2101 skb->used = 1;
2102 skb = skb->next;
2103 }2104 while (skb != (structsk_buff *)&sk->receive_queue);
2105
2106 if (copied)
2107 break;
2108
2109 if (sk->err)
2110 {2111 copied = -sk->err;
2112 sk->err = 0;
2113 break;
2114 }2115
2116 if (sk->state == TCP_CLOSE)
2117 {2118 if (!sk->done)
2119 {2120 sk->done = 1;
2121 break;
2122 }2123 copied = -ENOTCONN;
2124 break;
2125 }2126
2127 if (sk->shutdown & RCV_SHUTDOWN)
2128 {2129 sk->done = 1;
2130 break;
2131 }2132
2133 if (nonblock)
2134 {2135 copied = -EAGAIN;
2136 break;
2137 }2138
2139 cleanup_rbuf(sk);
2140 release_sock(sk);
2141 sk->socket->flags |= SO_WAITDATA;
2142 schedule();
2143 sk->socket->flags &= ~SO_WAITDATA;
2144 sk->inuse = 1;
2145
2146 if (current->signal & ~current->blocked)
2147 {2148 copied = -ERESTARTSYS;
2149 break;
2150 }2151 continue;
2152
2153 found_ok_skb:
2154 /*2155 * Lock the buffer. We can be fairly relaxed as2156 * an interrupt will never steal a buffer we are 2157 * using unless I've missed something serious in2158 * tcp_data.2159 */2160
2161 skb->users++;
2162
2163 /*2164 * Ok so how much can we use ? 2165 */2166
2167 used = skb->len - offset;
2168 if (len < used)
2169 used = len;
2170 /*2171 * Do we have urgent data here? 2172 */2173
2174 if (sk->urg_data)
2175 {2176 u32urg_offset = sk->urg_seq - *seq;
2177 if (urg_offset < used)
2178 {2179 if (!urg_offset)
2180 {2181 if (!sk->urginline)
2182 {2183 ++*seq;
2184 offset++;
2185 used--;
2186 }2187 }2188 else2189 used = urg_offset;
2190 }2191 }2192
2193 /*2194 * Copy it - We _MUST_ update *seq first so that we2195 * don't ever double read when we have dual readers2196 */2197
2198 *seq += used;
2199
2200 /*2201 * This memcpy_tofs can sleep. If it sleeps and we2202 * do a second read it relies on the skb->users to avoid2203 * a crash when cleanup_rbuf() gets called.2204 */2205
2206 memcpy_tofs(to,((unsignedchar *)skb->h.th) +
2207 skb->h.th->doff*4 + offset, used);
2208 copied += used;
2209 len -= used;
2210 to += used;
2211
2212 /*2213 * We now will not sleep again until we are finished2214 * with skb. Sorry if you are doing the SMP port2215 * but you'll just have to fix it neatly ;)2216 */2217
2218 skb->users --;
2219
2220 if (after(sk->copied_seq,sk->urg_seq))
2221 sk->urg_data = 0;
2222 if (used + offset < skb->len)
2223 continue;
2224
2225 /*2226 * Process the FIN.2227 */2228
2229 if (skb->h.th->fin)
2230 gotofound_fin_ok;
2231 if (flags & MSG_PEEK)
2232 continue;
2233 skb->used = 1;
2234 continue;
2235
2236 found_fin_ok:
2237 ++*seq;
2238 if (flags & MSG_PEEK)
2239 break;
2240
2241 /*2242 * All is done2243 */2244
2245 skb->used = 1;
2246 sk->shutdown |= RCV_SHUTDOWN;
2247 break;
2248
2249 }2250 remove_wait_queue(sk->sleep, &wait);
2251 current->state = TASK_RUNNING;
2252
2253 /* Clean up data we have read: This will do ACK frames */2254 cleanup_rbuf(sk);
2255 release_sock(sk);
2256 returncopied;
2257 }2258
2259 /*2260 * State processing on a close. This implements the state shift for2261 * sending our FIN frame. Note that we only send a FIN for some 2262 * states. A shutdown() may have already sent the FIN, or we may be2263 * closed.2264 */2265
2266 staticinttcp_close_state(structsock *sk, intdead)
/* */2267 {2268 intns=TCP_CLOSE;
2269 intsend_fin=0;
2270 switch(sk->state)
2271 {2272 caseTCP_SYN_SENT: /* No SYN back, no FIN needed */2273 break;
2274 caseTCP_SYN_RECV:
2275 caseTCP_ESTABLISHED: /* Closedown begin */2276 ns=TCP_FIN_WAIT1;
2277 send_fin=1;
2278 break;
2279 caseTCP_FIN_WAIT1: /* Already closing, or FIN sent: no change */2280 caseTCP_FIN_WAIT2:
2281 caseTCP_CLOSING:
2282 ns=sk->state;
2283 break;
2284 caseTCP_CLOSE:
2285 caseTCP_LISTEN:
2286 break;
2287 caseTCP_CLOSE_WAIT: /* They have FIN'd us. We send our FIN and2288 wait only for the ACK */2289 ns=TCP_LAST_ACK;
2290 send_fin=1;
2291 }2292
2293 tcp_set_state(sk,ns);
2294
2295 /*2296 * This is a (useful) BSD violating of the RFC. There is a2297 * problem with TCP as specified in that the other end could2298 * keep a socket open forever with no application left this end.2299 * We use a 3 minute timeout (about the same as BSD) then kill2300 * our end. If they send after that then tough - BUT: long enough2301 * that we won't make the old 4*rto = almost no time - whoops2302 * reset mistake.2303 */2304 if(dead && ns==TCP_FIN_WAIT2)
2305 {2306 inttimer_active=del_timer(&sk->timer);
2307 if(timer_active)
2308 add_timer(&sk->timer);
2309 else2310 reset_msl_timer(sk, TIME_CLOSE, TCP_FIN_TIMEOUT);
2311 }2312
2313 returnsend_fin;
2314 }2315
2316 /*2317 * Send a fin.2318 */2319
2320 staticvoidtcp_send_fin(structsock *sk)
/* */2321 {2322 structproto *prot =(structproto *)sk->prot;
2323 structtcphdr *th =(structtcphdr *)&sk->dummy_th;
2324 structtcphdr *t1;
2325 structsk_buff *buff;
2326 structdevice *dev=NULL;
2327 inttmp;
2328
2329 release_sock(sk); /* in case the malloc sleeps. */2330
2331 buff = prot->wmalloc(sk, MAX_RESET_SIZE,1 , GFP_KERNEL);
2332 sk->inuse = 1;
2333
2334 if (buff == NULL)
2335 {2336 /* This is a disaster if it occurs */2337 printk("tcp_send_fin: Impossible malloc failure");
2338 return;
2339 }2340
2341 /*2342 * Administrivia2343 */2344
2345 buff->sk = sk;
2346 buff->localroute = sk->localroute;
2347
2348 /*2349 * Put in the IP header and routing stuff. 2350 */2351
2352 tmp = prot->build_header(buff,sk->saddr, sk->daddr, &dev,
2353 IPPROTO_TCP, sk->opt,
2354 sizeof(structtcphdr),sk->ip_tos,sk->ip_ttl);
2355 if (tmp < 0)
2356 {2357 intt;
2358 /*2359 * Finish anyway, treat this as a send that got lost. 2360 * (Not good).2361 */2362
2363 buff->free = 1;
2364 prot->wfree(sk,buff);
2365 sk->write_seq++;
2366 t=del_timer(&sk->timer);
2367 if(t)
2368 add_timer(&sk->timer);
2369 else2370 reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
2371 return;
2372 }2373
2374 /*2375 * We ought to check if the end of the queue is a buffer and2376 * if so simply add the fin to that buffer, not send it ahead.2377 */2378
2379 t1 =(structtcphdr *)skb_put(buff,sizeof(structtcphdr));
2380 buff->dev = dev;
2381 memcpy(t1, th, sizeof(*t1));
2382 t1->seq = ntohl(sk->write_seq);
2383 sk->write_seq++;
2384 buff->h.seq = sk->write_seq;
2385 t1->ack = 1;
2386 t1->ack_seq = ntohl(sk->acked_seq);
2387 t1->window = ntohs(sk->window=tcp_select_window(sk));
2388 t1->fin = 1;
2389 t1->rst = 0;
2390 t1->doff = sizeof(*t1)/4;
2391 tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), sk);
2392
2393 /*2394 * If there is data in the write queue, the fin must be appended to2395 * the write queue.2396 */2397
2398 if (skb_peek(&sk->write_queue) != NULL)
2399 {2400 buff->free = 0;
2401 if (buff->next != NULL)
2402 {2403 printk("tcp_send_fin: next != NULL\n");
2404 skb_unlink(buff);
2405 }2406 skb_queue_tail(&sk->write_queue, buff);
2407 }2408 else2409 {2410 sk->sent_seq = sk->write_seq;
2411 sk->prot->queue_xmit(sk, dev, buff, 0);
2412 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
2413 }2414 }2415
2416 /*2417 * Shutdown the sending side of a connection. Much like close except2418 * that we don't receive shut down or set sk->dead=1.2419 */2420
2421 voidtcp_shutdown(structsock *sk, inthow)
/* */2422 {2423 /*2424 * We need to grab some memory, and put together a FIN,2425 * and then put it into the queue to be sent.2426 * Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.2427 */2428
2429 if (!(how & SEND_SHUTDOWN))
2430 return;
2431
2432 /*2433 * If we've already sent a FIN, or it's a closed state2434 */2435
2436 if (sk->state == TCP_FIN_WAIT1 ||
2437 sk->state == TCP_FIN_WAIT2 ||
2438 sk->state == TCP_CLOSING ||
2439 sk->state == TCP_LAST_ACK ||
2440 sk->state == TCP_TIME_WAIT ||
2441 sk->state == TCP_CLOSE ||
2442 sk->state == TCP_LISTEN2443 )
2444 {2445 return;
2446 }2447 sk->inuse = 1;
2448
2449 /*2450 * flag that the sender has shutdown2451 */2452
2453 sk->shutdown |= SEND_SHUTDOWN;
2454
2455 /*2456 * Clear out any half completed packets. 2457 */2458
2459 if (sk->partial)
2460 tcp_send_partial(sk);
2461
2462 /*2463 * FIN if needed2464 */2465
2466 if(tcp_close_state(sk,0))
2467 tcp_send_fin(sk);
2468
2469 release_sock(sk);
2470 }2471
2472
2473 staticint2474 tcp_recvfrom(structsock *sk, unsignedchar *to,
/* */2475 intto_len, intnonblock, unsignedflags,
2476 structsockaddr_in *addr, int *addr_len)
2477 {2478 intresult;
2479
2480 /* 2481 * Have to check these first unlike the old code. If 2482 * we check them after we lose data on an error2483 * which is wrong 2484 */2485
2486 if(addr_len)
2487 *addr_len = sizeof(*addr);
2488 result=tcp_read(sk, to, to_len, nonblock, flags);
2489
2490 if (result < 0)
2491 return(result);
2492
2493 if(addr)
2494 {2495 addr->sin_family = AF_INET;
2496 addr->sin_port = sk->dummy_th.dest;
2497 addr->sin_addr.s_addr = sk->daddr;
2498 }2499 return(result);
2500 }2501
2502
2503 /*2504 * This routine will send an RST to the other tcp. 2505 */2506
2507 staticvoidtcp_reset(unsignedlongsaddr, unsignedlongdaddr, structtcphdr *th,
/* */2508 structproto *prot, structoptions *opt, structdevice *dev, inttos, intttl)
2509 {2510 structsk_buff *buff;
2511 structtcphdr *t1;
2512 inttmp;
2513 structdevice *ndev=NULL;
2514
2515 /*2516 * Cannot reset a reset (Think about it).2517 */2518
2519 if(th->rst)
2520 return;
2521
2522 /*2523 * We need to grab some memory, and put together an RST,2524 * and then put it into the queue to be sent.2525 */2526
2527 buff = prot->wmalloc(NULL, MAX_RESET_SIZE, 1, GFP_ATOMIC);
2528 if (buff == NULL)
2529 return;
2530
2531 buff->sk = NULL;
2532 buff->dev = dev;
2533 buff->localroute = 0;
2534
2535 /*2536 * Put in the IP header and routing stuff. 2537 */2538
2539 tmp = prot->build_header(buff, saddr, daddr, &ndev, IPPROTO_TCP, opt,
2540 sizeof(structtcphdr),tos,ttl);
2541 if (tmp < 0)
2542 {2543 buff->free = 1;
2544 prot->wfree(NULL, buff);
2545 return;
2546 }2547
2548 t1 =(structtcphdr *)skb_put(buff,sizeof(structtcphdr));
2549 memcpy(t1, th, sizeof(*t1));
2550
2551 /*2552 * Swap the send and the receive. 2553 */2554
2555 t1->dest = th->source;
2556 t1->source = th->dest;
2557 t1->rst = 1;
2558 t1->window = 0;
2559
2560 if(th->ack)
2561 {2562 t1->ack = 0;
2563 t1->seq = th->ack_seq;
2564 t1->ack_seq = 0;
2565 }2566 else2567 {2568 t1->ack = 1;
2569 if(!th->syn)
2570 t1->ack_seq=htonl(th->seq);
2571 else2572 t1->ack_seq=htonl(th->seq+1);
2573 t1->seq=0;
2574 }2575
2576 t1->syn = 0;
2577 t1->urg = 0;
2578 t1->fin = 0;
2579 t1->psh = 0;
2580 t1->doff = sizeof(*t1)/4;
2581 tcp_send_check(t1, saddr, daddr, sizeof(*t1), NULL);
2582 prot->queue_xmit(NULL, ndev, buff, 1);
2583 tcp_statistics.TcpOutSegs++;
2584 }2585
2586
2587 /*2588 * Look for tcp options. Parses everything but only knows about MSS.2589 * This routine is always called with the packet containing the SYN.2590 * However it may also be called with the ack to the SYN. So you2591 * can't assume this is always the SYN. It's always called after2592 * we have set up sk->mtu to our own MTU.2593 *2594 * We need at minimum to add PAWS support here. Possibly large windows2595 * as Linux gets deployed on 100Mb/sec networks.2596 */2597
2598 staticvoidtcp_options(structsock *sk, structtcphdr *th)
/* */2599 {2600 unsignedchar *ptr;
2601 intlength=(th->doff*4)-sizeof(structtcphdr);
2602 intmss_seen = 0;
2603
2604 ptr = (unsignedchar *)(th + 1);
2605
2606 while(length>0)
2607 {2608 intopcode=*ptr++;
2609 intopsize=*ptr++;
2610 switch(opcode)
2611 {2612 caseTCPOPT_EOL:
2613 return;
2614 caseTCPOPT_NOP: /* Ref: RFC 793 section 3.1 */2615 length--;
2616 ptr--; /* the opsize=*ptr++ above was a mistake */2617 continue;
2618
2619 default:
2620 if(opsize<=2) /* Avoid silly options looping forever */2621 return;
2622 switch(opcode)
2623 {2624 caseTCPOPT_MSS:
2625 if(opsize==4 && th->syn)
2626 {2627 sk->mtu=min(sk->mtu,ntohs(*(unsignedshort *)ptr));
2628 mss_seen = 1;
2629 }2630 break;
2631 /* Add other options here as people feel the urge to implement stuff like large windows */2632 }2633 ptr+=opsize-2;
2634 length-=opsize;
2635 }2636 }2637 if (th->syn)
2638 {2639 if (! mss_seen)
2640 sk->mtu=min(sk->mtu, 536); /* default MSS if none sent */2641 }2642 #ifdefCONFIG_INET_PCTCP2643 sk->mss = min(sk->max_window >> 1, sk->mtu);
2644 #else2645 sk->mss = min(sk->max_window, sk->mtu);
2646 #endif2647 }2648
2649 staticinlineunsignedlongdefault_mask(unsignedlongdst)
/* */2650 {2651 dst = ntohl(dst);
2652 if (IN_CLASSA(dst))
2653 returnhtonl(IN_CLASSA_NET);
2654 if (IN_CLASSB(dst))
2655 returnhtonl(IN_CLASSB_NET);
2656 returnhtonl(IN_CLASSC_NET);
2657 }2658
2659 /*2660 * Default sequence number picking algorithm.2661 * As close as possible to RFC 793, which2662 * suggests using a 250kHz clock.2663 * Further reading shows this assumes 2MB/s networks.2664 * For 10MB/s ethernet, a 1MHz clock is appropriate.2665 * That's funny, Linux has one built in! Use it!2666 */2667
2668 externinlineu32tcp_init_seq(void)
/* */2669 {2670 structtimevaltv;
2671 do_gettimeofday(&tv);
2672 returntv.tv_usec+tv.tv_sec*1000000;
2673 }2674
2675 /*2676 * This routine handles a connection request.2677 * It should make sure we haven't already responded.2678 * Because of the way BSD works, we have to send a syn/ack now.2679 * This also means it will be harder to close a socket which is2680 * listening.2681 */2682
2683 staticvoidtcp_conn_request(structsock *sk, structsk_buff *skb,
/* */2684 unsignedlongdaddr, unsignedlongsaddr,
2685 structoptions *opt, structdevice *dev, u32seq)
2686 {2687 structsk_buff *buff;
2688 structtcphdr *t1;
2689 unsignedchar *ptr;
2690 structsock *newsk;
2691 structtcphdr *th;
2692 structdevice *ndev=NULL;
2693 inttmp;
2694 structrtable *rt;
2695
2696 th = skb->h.th;
2697
2698 /* If the socket is dead, don't accept the connection. */2699 if (!sk->dead)
2700 {2701 sk->data_ready(sk,0);
2702 }2703 else2704 {2705 if(sk->debug)
2706 printk("Reset on %p: Connect on dead socket.\n",sk);
2707 tcp_reset(daddr, saddr, th, sk->prot, opt, dev, sk->ip_tos,sk->ip_ttl);
2708 tcp_statistics.TcpAttemptFails++;
2709 kfree_skb(skb, FREE_READ);
2710 return;
2711 }2712
2713 /*2714 * Make sure we can accept more. This will prevent a2715 * flurry of syns from eating up all our memory.2716 */2717
2718 if (sk->ack_backlog >= sk->max_ack_backlog)
2719 {2720 tcp_statistics.TcpAttemptFails++;
2721 kfree_skb(skb, FREE_READ);
2722 return;
2723 }2724
2725 /*2726 * We need to build a new sock struct.2727 * It is sort of bad to have a socket without an inode attached2728 * to it, but the wake_up's will just wake up the listening socket,2729 * and if the listening socket is destroyed before this is taken2730 * off of the queue, this will take care of it.2731 */2732
2733 newsk = (structsock *) kmalloc(sizeof(structsock), GFP_ATOMIC);
2734 if (newsk == NULL)
2735 {2736 /* just ignore the syn. It will get retransmitted. */2737 tcp_statistics.TcpAttemptFails++;
2738 kfree_skb(skb, FREE_READ);
2739 return;
2740 }2741
2742 memcpy(newsk, sk, sizeof(*newsk));
2743 skb_queue_head_init(&newsk->write_queue);
2744 skb_queue_head_init(&newsk->receive_queue);
2745 newsk->send_head = NULL;
2746 newsk->send_tail = NULL;
2747 skb_queue_head_init(&newsk->back_log);
2748 newsk->rtt = 0; /*TCP_CONNECT_TIME<<3*/2749 newsk->rto = TCP_TIMEOUT_INIT;
2750 newsk->mdev = 0;
2751 newsk->max_window = 0;
2752 newsk->cong_window = 1;
2753 newsk->cong_count = 0;
2754 newsk->ssthresh = 0;
2755 newsk->backoff = 0;
2756 newsk->blog = 0;
2757 newsk->intr = 0;
2758 newsk->proc = 0;
2759 newsk->done = 0;
2760 newsk->partial = NULL;
2761 newsk->pair = NULL;
2762 newsk->wmem_alloc = 0;
2763 newsk->rmem_alloc = 0;
2764 newsk->localroute = sk->localroute;
2765
2766 newsk->max_unacked = MAX_WINDOW - TCP_WINDOW_DIFF;
2767
2768 newsk->err = 0;
2769 newsk->shutdown = 0;
2770 newsk->ack_backlog = 0;
2771 newsk->acked_seq = skb->h.th->seq+1;
2772 newsk->copied_seq = skb->h.th->seq+1;
2773 newsk->fin_seq = skb->h.th->seq;
2774 newsk->state = TCP_SYN_RECV;
2775 newsk->timeout = 0;
2776 newsk->ip_xmit_timeout = 0;
2777 newsk->write_seq = seq;
2778 newsk->window_seq = newsk->write_seq;
2779 newsk->rcv_ack_seq = newsk->write_seq;
2780 newsk->urg_data = 0;
2781 newsk->retransmits = 0;
2782 newsk->linger=0;
2783 newsk->destroy = 0;
2784 init_timer(&newsk->timer);
2785 newsk->timer.data = (unsignedlong)newsk;
2786 newsk->timer.function = &net_timer;
2787 init_timer(&newsk->retransmit_timer);
2788 newsk->retransmit_timer.data = (unsignedlong)newsk;
2789 newsk->retransmit_timer.function=&retransmit_timer;
2790 newsk->dummy_th.source = skb->h.th->dest;
2791 newsk->dummy_th.dest = skb->h.th->source;
2792
2793 /*2794 * Swap these two, they are from our point of view. 2795 */2796
2797 newsk->daddr = saddr;
2798 newsk->saddr = daddr;
2799
2800 put_sock(newsk->num,newsk);
2801 newsk->dummy_th.res1 = 0;
2802 newsk->dummy_th.doff = 6;
2803 newsk->dummy_th.fin = 0;
2804 newsk->dummy_th.syn = 0;
2805 newsk->dummy_th.rst = 0;
2806 newsk->dummy_th.psh = 0;
2807 newsk->dummy_th.ack = 0;
2808 newsk->dummy_th.urg = 0;
2809 newsk->dummy_th.res2 = 0;
2810 newsk->acked_seq = skb->h.th->seq + 1;
2811 newsk->copied_seq = skb->h.th->seq + 1;
2812 newsk->socket = NULL;
2813
2814 /*2815 * Grab the ttl and tos values and use them 2816 */2817
2818 newsk->ip_ttl=sk->ip_ttl;
2819 newsk->ip_tos=skb->ip_hdr->tos;
2820
2821 /*2822 * Use 512 or whatever user asked for 2823 */2824
2825 /*2826 * Note use of sk->user_mss, since user has no direct access to newsk 2827 */2828
2829 rt=ip_rt_route(saddr, NULL,NULL);
2830
2831 if(rt!=NULL && (rt->rt_flags&RTF_WINDOW))
2832 newsk->window_clamp = rt->rt_window;
2833 else2834 newsk->window_clamp = 0;
2835
2836 if (sk->user_mss)
2837 newsk->mtu = sk->user_mss;
2838 elseif(rt!=NULL && (rt->rt_flags&RTF_MSS))
2839 newsk->mtu = rt->rt_mss - HEADER_SIZE;
2840 else2841 {2842 #ifdefCONFIG_INET_SNARL/* Sub Nets Are Local */2843 if ((saddr ^ daddr) & default_mask(saddr))
2844 #else2845 if ((saddr ^ daddr) & dev->pa_mask)
2846 #endif2847 newsk->mtu = 576 - HEADER_SIZE;
2848 else2849 newsk->mtu = MAX_WINDOW;
2850 }2851
2852 /*2853 * But not bigger than device MTU 2854 */2855
2856 newsk->mtu = min(newsk->mtu, dev->mtu - HEADER_SIZE);
2857
2858 /*2859 * This will min with what arrived in the packet 2860 */2861
2862 tcp_options(newsk,skb->h.th);
2863
2864 tcp_cache_zap();
2865
2866 buff = newsk->prot->wmalloc(newsk, MAX_SYN_SIZE, 1, GFP_ATOMIC);
2867 if (buff == NULL)
2868 {2869 sk->err = ENOMEM;
2870 newsk->dead = 1;
2871 newsk->state = TCP_CLOSE;
2872 /* And this will destroy it */2873 release_sock(newsk);
2874 kfree_skb(skb, FREE_READ);
2875 tcp_statistics.TcpAttemptFails++;
2876 return;
2877 }2878
2879 buff->sk = newsk;
2880 buff->localroute = newsk->localroute;
2881
2882 /*2883 * Put in the IP header and routing stuff. 2884 */2885
2886 tmp = sk->prot->build_header(buff, newsk->saddr, newsk->daddr, &ndev,
2887 IPPROTO_TCP, NULL, MAX_SYN_SIZE,sk->ip_tos,sk->ip_ttl);
2888
2889 /*2890 * Something went wrong. 2891 */2892
2893 if (tmp < 0)
2894 {2895 sk->err = tmp;
2896 buff->free = 1;
2897 kfree_skb(buff,FREE_WRITE);
2898 newsk->dead = 1;
2899 newsk->state = TCP_CLOSE;
2900 release_sock(newsk);
2901 skb->sk = sk;
2902 kfree_skb(skb, FREE_READ);
2903 tcp_statistics.TcpAttemptFails++;
2904 return;
2905 }2906
2907 t1 =(structtcphdr *)skb_put(buff,sizeof(structtcphdr));
2908
2909 memcpy(t1, skb->h.th, sizeof(*t1));
2910 buff->h.seq = newsk->write_seq;
2911 /*2912 * Swap the send and the receive. 2913 */2914 t1->dest = skb->h.th->source;
2915 t1->source = newsk->dummy_th.source;
2916 t1->seq = ntohl(newsk->write_seq++);
2917 t1->ack = 1;
2918 newsk->window = tcp_select_window(newsk);
2919 newsk->sent_seq = newsk->write_seq;
2920 t1->window = ntohs(newsk->window);
2921 t1->res1 = 0;
2922 t1->res2 = 0;
2923 t1->rst = 0;
2924 t1->urg = 0;
2925 t1->psh = 0;
2926 t1->syn = 1;
2927 t1->ack_seq = ntohl(skb->h.th->seq+1);
2928 t1->doff = sizeof(*t1)/4+1;
2929 ptr = skb_put(buff,4);
2930 ptr[0] = 2;
2931 ptr[1] = 4;
2932 ptr[2] = ((newsk->mtu) >> 8) & 0xff;
2933 ptr[3] =(newsk->mtu) & 0xff;
2934
2935 tcp_send_check(t1, daddr, saddr, sizeof(*t1)+4, newsk);
2936 newsk->prot->queue_xmit(newsk, ndev, buff, 0);
2937 reset_xmit_timer(newsk, TIME_WRITE , TCP_TIMEOUT_INIT);
2938 skb->sk = newsk;
2939
2940 /*2941 * Charge the sock_buff to newsk. 2942 */2943
2944 sk->rmem_alloc -= skb->truesize;
2945 newsk->rmem_alloc += skb->truesize;
2946
2947 skb_queue_tail(&sk->receive_queue,skb);
2948 sk->ack_backlog++;
2949 release_sock(newsk);
2950 tcp_statistics.TcpOutSegs++;
2951 }2952
2953
2954 staticvoidtcp_close(structsock *sk, inttimeout)
/* */2955 {2956 /*2957 * We need to grab some memory, and put together a FIN, 2958 * and then put it into the queue to be sent.2959 */2960
2961 sk->inuse = 1;
2962
2963 if(th_cache_sk==sk)
2964 tcp_cache_zap();
2965 if(sk->state == TCP_LISTEN)
2966 {2967 /* Special case */2968 tcp_set_state(sk, TCP_CLOSE);
2969 tcp_close_pending(sk);
2970 release_sock(sk);
2971 return;
2972 }2973
2974 sk->keepopen = 1;
2975 sk->shutdown = SHUTDOWN_MASK;
2976
2977 if (!sk->dead)
2978 sk->state_change(sk);
2979
2980 if (timeout == 0)
2981 {2982 structsk_buff *skb;
2983
2984 /*2985 * We need to flush the recv. buffs. We do this only on the2986 * descriptor close, not protocol-sourced closes, because the2987 * reader process may not have drained the data yet!2988 */2989
2990 while((skb=skb_dequeue(&sk->receive_queue))!=NULL)
2991 kfree_skb(skb, FREE_READ);
2992 /*2993 * Get rid off any half-completed packets. 2994 */2995
2996 if (sk->partial)
2997 tcp_send_partial(sk);
2998 }2999
3000
3001 /*3002 * Timeout is not the same thing - however the code likes3003 * to send both the same way (sigh).3004 */3005
3006 if(timeout)
3007 {3008 tcp_set_state(sk, TCP_CLOSE); /* Dead */3009 }3010 else3011 {3012 if(tcp_close_state(sk,1)==1)
3013 {3014 tcp_send_fin(sk);
3015 }3016 }3017 release_sock(sk);
3018 }3019
3020
3021 /*3022 * This routine takes stuff off of the write queue,3023 * and puts it in the xmit queue. This happens as incoming acks3024 * open up the remote window for us.3025 */3026
3027 staticvoidtcp_write_xmit(structsock *sk)
/* */3028 {3029 structsk_buff *skb;
3030
3031 /*3032 * The bytes will have to remain here. In time closedown will3033 * empty the write queue and all will be happy 3034 */3035
3036 if(sk->zapped)
3037 return;
3038
3039 /*3040 * Anything on the transmit queue that fits the window can3041 * be added providing we are not3042 *3043 * a) retransmitting (Nagle's rule)3044 * b) exceeding our congestion window.3045 */3046
3047 while((skb = skb_peek(&sk->write_queue)) != NULL &&
3048 before(skb->h.seq, sk->window_seq + 1) &&
3049 (sk->retransmits == 0 ||
3050 sk->ip_xmit_timeout != TIME_WRITE ||
3051 before(skb->h.seq, sk->rcv_ack_seq + 1))
3052 && sk->packets_out < sk->cong_window)
3053 {3054 IS_SKB(skb);
3055 skb_unlink(skb);
3056
3057 /*3058 * See if we really need to send the packet. 3059 */3060
3061 if (before(skb->h.seq, sk->rcv_ack_seq +1))
3062 {3063 /*3064 * This is acked data. We can discard it. This 3065 * cannot currently occur.3066 */3067
3068 sk->retransmits = 0;
3069 kfree_skb(skb, FREE_WRITE);
3070 if (!sk->dead)
3071 sk->write_space(sk);
3072 }3073 else3074 {3075 structtcphdr *th;
3076 structiphdr *iph;
3077 intsize;
3078 /*3079 * put in the ack seq and window at this point rather than earlier,3080 * in order to keep them monotonic. We really want to avoid taking3081 * back window allocations. That's legal, but RFC1122 says it's frowned on.3082 * Ack and window will in general have changed since this packet was put3083 * on the write queue.3084 */3085 iph = skb->ip_hdr;
3086 th = (structtcphdr *)(((char *)iph) +(iph->ihl << 2));
3087 size = skb->len - (((unsignedchar *) th) - skb->data);
3088
3089 th->ack_seq = ntohl(sk->acked_seq);
3090 th->window = ntohs(tcp_select_window(sk));
3091
3092 tcp_send_check(th, sk->saddr, sk->daddr, size, sk);
3093
3094 sk->sent_seq = skb->h.seq;
3095
3096 /*3097 * IP manages our queue for some crazy reason3098 */3099
3100 sk->prot->queue_xmit(sk, skb->dev, skb, skb->free);
3101
3102 /*3103 * Again we slide the timer wrongly3104 */3105
3106 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
3107 }3108 }3109 }3110
3111
3112 /*3113 * This routine deals with incoming acks, but not outgoing ones.3114 */3115
3116 extern__inline__inttcp_ack(structsock *sk, structtcphdr *th, unsignedlongsaddr, intlen)
/* */3117 {3118 u32ack;
3119 intflag = 0;
3120
3121 /* 3122 * 1 - there was data in packet as well as ack or new data is sent or 3123 * in shutdown state3124 * 2 - data from retransmit queue was acked and removed3125 * 4 - window shrunk or data from retransmit queue was acked and removed3126 */3127
3128 if(sk->zapped)
3129 return(1); /* Dead, cant ack any more so why bother */3130
3131 /*3132 * Have we discovered a larger window3133 */3134
3135 ack = ntohl(th->ack_seq);
3136
3137 if (ntohs(th->window) > sk->max_window)
3138 {3139 sk->max_window = ntohs(th->window);
3140 #ifdefCONFIG_INET_PCTCP3141 /* Hack because we don't send partial packets to non SWS3142 handling hosts */3143 sk->mss = min(sk->max_window>>1, sk->mtu);
3144 #else3145 sk->mss = min(sk->max_window, sk->mtu);
3146 #endif3147 }3148
3149 /*3150 * We have dropped back to keepalive timeouts. Thus we have3151 * no retransmits pending.3152 */3153
3154 if (sk->retransmits && sk->ip_xmit_timeout == TIME_KEEPOPEN)
3155 sk->retransmits = 0;
3156
3157 /*3158 * If the ack is newer than sent or older than previous acks3159 * then we can probably ignore it.3160 */3161
3162 if (after(ack, sk->sent_seq) || before(ack, sk->rcv_ack_seq))
3163 {3164 if(sk->debug)
3165 printk("Ack ignored %u %u\n",ack,sk->sent_seq);
3166
3167 /*3168 * Keepalive processing.3169 */3170
3171 if (after(ack, sk->sent_seq))
3172 {3173 return(0);
3174 }3175
3176 /*3177 * Restart the keepalive timer.3178 */3179
3180 if (sk->keepopen)
3181 {3182 if(sk->ip_xmit_timeout==TIME_KEEPOPEN)
3183 reset_xmit_timer(sk, TIME_KEEPOPEN, TCP_TIMEOUT_LEN);
3184 }3185 return(1);
3186 }3187
3188 /*3189 * If there is data set flag 13190 */3191
3192 if (len != th->doff*4)
3193 flag |= 1;
3194
3195 /*3196 * See if our window has been shrunk. 3197 */3198
3199 if (after(sk->window_seq, ack+ntohs(th->window)))
3200 {3201 /*3202 * We may need to move packets from the send queue3203 * to the write queue, if the window has been shrunk on us.3204 * The RFC says you are not allowed to shrink your window3205 * like this, but if the other end does, you must be able3206 * to deal with it.3207 */3208 structsk_buff *skb;
3209 structsk_buff *skb2;
3210 structsk_buff *wskb = NULL;
3211
3212 skb2 = sk->send_head;
3213 sk->send_head = NULL;
3214 sk->send_tail = NULL;
3215
3216 /*3217 * This is an artifact of a flawed concept. We want one3218 * queue and a smarter send routine when we send all.3219 */3220
3221 flag |= 4; /* Window changed */3222
3223 sk->window_seq = ack + ntohs(th->window);
3224 cli();
3225 while (skb2 != NULL)
3226 {3227 skb = skb2;
3228 skb2 = skb->link3;
3229 skb->link3 = NULL;
3230 if (after(skb->h.seq, sk->window_seq))
3231 {3232 if (sk->packets_out > 0)
3233 sk->packets_out--;
3234 /* We may need to remove this from the dev send list. */3235 if (skb->next != NULL)
3236 {3237 skb_unlink(skb);
3238 }3239 /* Now add it to the write_queue. */3240 if (wskb == NULL)
3241 skb_queue_head(&sk->write_queue,skb);
3242 else3243 skb_append(wskb,skb);
3244 wskb = skb;
3245 }3246 else3247 {3248 if (sk->send_head == NULL)
3249 {3250 sk->send_head = skb;
3251 sk->send_tail = skb;
3252 }3253 else3254 {3255 sk->send_tail->link3 = skb;
3256 sk->send_tail = skb;
3257 }3258 skb->link3 = NULL;
3259 }3260 }3261 sti();
3262 }3263
3264 /*3265 * Pipe has emptied3266 */3267
3268 if (sk->send_tail == NULL || sk->send_head == NULL)
3269 {3270 sk->send_head = NULL;
3271 sk->send_tail = NULL;
3272 sk->packets_out= 0;
3273 }3274
3275 /*3276 * Update the right hand window edge of the host3277 */3278
3279 sk->window_seq = ack + ntohs(th->window);
3280
3281 /*3282 * We don't want too many packets out there. 3283 */3284
3285 if (sk->ip_xmit_timeout == TIME_WRITE &&
3286 sk->cong_window < 2048 && after(ack, sk->rcv_ack_seq))
3287 {3288 /* 3289 * This is Jacobson's slow start and congestion avoidance. 3290 * SIGCOMM '88, p. 328. Because we keep cong_window in integral3291 * mss's, we can't do cwnd += 1 / cwnd. Instead, maintain a 3292 * counter and increment it once every cwnd times. It's possible3293 * that this should be done only if sk->retransmits == 0. I'm3294 * interpreting "new data is acked" as including data that has3295 * been retransmitted but is just now being acked.3296 */3297 if (sk->cong_window < sk->ssthresh)
3298 /* 3299 * In "safe" area, increase3300 */3301 sk->cong_window++;
3302 else3303 {3304 /*3305 * In dangerous area, increase slowly. In theory this is3306 * sk->cong_window += 1 / sk->cong_window3307 */3308 if (sk->cong_count >= sk->cong_window)
3309 {3310 sk->cong_window++;
3311 sk->cong_count = 0;
3312 }3313 else3314 sk->cong_count++;
3315 }3316 }3317
3318 /*3319 * Remember the highest ack received.3320 */3321
3322 sk->rcv_ack_seq = ack;
3323
3324 /*3325 * If this ack opens up a zero window, clear backoff. It was3326 * being used to time the probes, and is probably far higher than3327 * it needs to be for normal retransmission.3328 */3329
3330 if (sk->ip_xmit_timeout == TIME_PROBE0)
3331 {3332 sk->retransmits = 0; /* Our probe was answered */3333
3334 /*3335 * Was it a usable window open ?3336 */3337
3338 if (skb_peek(&sk->write_queue) != NULL && /* should always be non-null */3339 ! before (sk->window_seq, sk->write_queue.next->h.seq))
3340 {3341 sk->backoff = 0;
3342
3343 /*3344 * Recompute rto from rtt. this eliminates any backoff.3345 */3346
3347 sk->rto = ((sk->rtt >> 2) + sk->mdev) >> 1;
3348 if (sk->rto > 120*HZ)
3349 sk->rto = 120*HZ;
3350 if (sk->rto < 20) /* Was 1*HZ, then 1 - turns out we must allow about3351 .2 of a second because of BSD delayed acks - on a 100Mb/sec link3352 .2 of a second is going to need huge windows (SIGH) */3353 sk->rto = 20;
3354 }3355 }3356
3357 /* 3358 * See if we can take anything off of the retransmit queue.3359 */3360
3361 while(sk->send_head != NULL)
3362 {3363 /* Check for a bug. */3364 if (sk->send_head->link3 &&
3365 after(sk->send_head->h.seq, sk->send_head->link3->h.seq))
3366 printk("INET: tcp.c: *** bug send_list out of order.\n");
3367
3368 /*3369 * If our packet is before the ack sequence we can3370 * discard it as it's confirmed to have arrived the other end.3371 */3372
3373 if (before(sk->send_head->h.seq, ack+1))
3374 {3375 structsk_buff *oskb;
3376 if (sk->retransmits)
3377 {3378 /*3379 * We were retransmitting. don't count this in RTT est 3380 */3381 flag |= 2;
3382
3383 /*3384 * even though we've gotten an ack, we're still3385 * retransmitting as long as we're sending from3386 * the retransmit queue. Keeping retransmits non-zero3387 * prevents us from getting new data interspersed with3388 * retransmissions.3389 */3390
3391 if (sk->send_head->link3) /* Any more queued retransmits? */3392 sk->retransmits = 1;
3393 else3394 sk->retransmits = 0;
3395 }3396 /*3397 * Note that we only reset backoff and rto in the3398 * rtt recomputation code. And that doesn't happen3399 * if there were retransmissions in effect. So the3400 * first new packet after the retransmissions is3401 * sent with the backoff still in effect. Not until3402 * we get an ack from a non-retransmitted packet do3403 * we reset the backoff and rto. This allows us to deal3404 * with a situation where the network delay has increased3405 * suddenly. I.e. Karn's algorithm. (SIGCOMM '87, p5.)3406 */3407
3408 /*3409 * We have one less packet out there. 3410 */3411
3412 if (sk->packets_out > 0)
3413 sk->packets_out --;
3414 /* 3415 * Wake up the process, it can probably write more. 3416 */3417 if (!sk->dead)
3418 sk->write_space(sk);
3419 oskb = sk->send_head;
3420
3421 if (!(flag&2)) /* Not retransmitting */3422 {3423 longm;
3424
3425 /*3426 * The following amusing code comes from Jacobson's3427 * article in SIGCOMM '88. Note that rtt and mdev3428 * are scaled versions of rtt and mean deviation.3429 * This is designed to be as fast as possible 3430 * m stands for "measurement".3431 */3432
3433 m = jiffies - oskb->when; /* RTT */3434 if(m<=0)
3435 m=1; /* IS THIS RIGHT FOR <0 ??? */3436 m -= (sk->rtt >> 3); /* m is now error in rtt est */3437 sk->rtt += m; /* rtt = 7/8 rtt + 1/8 new */3438 if (m < 0)
3439 m = -m; /* m is now abs(error) */3440 m -= (sk->mdev >> 2); /* similar update on mdev */3441 sk->mdev += m; /* mdev = 3/4 mdev + 1/4 new */3442
3443 /*3444 * Now update timeout. Note that this removes any backoff.3445 */3446
3447 sk->rto = ((sk->rtt >> 2) + sk->mdev) >> 1;
3448 if (sk->rto > 120*HZ)
3449 sk->rto = 120*HZ;
3450 if (sk->rto < 20) /* Was 1*HZ - keep .2 as minimum cos of the BSD delayed acks */3451 sk->rto = 20;
3452 sk->backoff = 0;
3453 }3454 flag |= (2|4); /* 2 is really more like 'don't adjust the rtt 3455 In this case as we just set it up */3456 cli();
3457 oskb = sk->send_head;
3458 IS_SKB(oskb);
3459 sk->send_head = oskb->link3;
3460 if (sk->send_head == NULL)
3461 {3462 sk->send_tail = NULL;
3463 }3464
3465 /*3466 * We may need to remove this from the dev send list. 3467 */3468
3469 if (oskb->next)
3470 skb_unlink(oskb);
3471 sti();
3472 kfree_skb(oskb, FREE_WRITE); /* write. */3473 if (!sk->dead)
3474 sk->write_space(sk);
3475 }3476 else3477 {3478 break;
3479 }3480 }3481
3482 /*3483 * XXX someone ought to look at this too.. at the moment, if skb_peek()3484 * returns non-NULL, we complete ignore the timer stuff in the else3485 * clause. We ought to organize the code so that else clause can3486 * (should) be executed regardless, possibly moving the PROBE timer3487 * reset over. The skb_peek() thing should only move stuff to the3488 * write queue, NOT also manage the timer functions.3489 */3490
3491 /*3492 * Maybe we can take some stuff off of the write queue,3493 * and put it onto the xmit queue.3494 */3495 if (skb_peek(&sk->write_queue) != NULL)
3496 {3497 if (after (sk->window_seq+1, sk->write_queue.next->h.seq) &&
3498 (sk->retransmits == 0 ||
3499 sk->ip_xmit_timeout != TIME_WRITE ||
3500 before(sk->write_queue.next->h.seq, sk->rcv_ack_seq + 1))
3501 && sk->packets_out < sk->cong_window)
3502 {3503 /*3504 * Add more data to the send queue.3505 */3506 flag |= 1;
3507 tcp_write_xmit(sk);
3508 }3509 elseif (before(sk->window_seq, sk->write_queue.next->h.seq) &&
3510 sk->send_head == NULL &&
3511 sk->ack_backlog == 0 &&
3512 sk->state != TCP_TIME_WAIT)
3513 {3514 /*3515 * Data to queue but no room.3516 */3517 reset_xmit_timer(sk, TIME_PROBE0, sk->rto);
3518 }3519 }3520 else3521 {3522 /*3523 * from TIME_WAIT we stay in TIME_WAIT as long as we rx packets3524 * from TCP_CLOSE we don't do anything3525 *3526 * from anything else, if there is write data (or fin) pending,3527 * we use a TIME_WRITE timeout, else if keepalive we reset to3528 * a KEEPALIVE timeout, else we delete the timer.3529 *3530 * We do not set flag for nominal write data, otherwise we may3531 * force a state where we start to write itsy bitsy tidbits3532 * of data.3533 */3534
3535 switch(sk->state) {3536 caseTCP_TIME_WAIT:
3537 /*3538 * keep us in TIME_WAIT until we stop getting packets,3539 * reset the timeout.3540 */3541 reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
3542 break;
3543 caseTCP_CLOSE:
3544 /*3545 * don't touch the timer.3546 */3547 break;
3548 default:
3549 /*3550 * Must check send_head, write_queue, and ack_backlog3551 * to determine which timeout to use.3552 */3553 if (sk->send_head || skb_peek(&sk->write_queue) != NULL || sk->ack_backlog) {3554 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
3555 }elseif (sk->keepopen) {3556 reset_xmit_timer(sk, TIME_KEEPOPEN, TCP_TIMEOUT_LEN);
3557 }else{3558 del_timer(&sk->retransmit_timer);
3559 sk->ip_xmit_timeout = 0;
3560 }3561 break;
3562 }3563 }3564
3565 /*3566 * We have nothing queued but space to send. Send any partial3567 * packets immediately (end of Nagle rule application).3568 */3569
3570 if (sk->packets_out == 0 && sk->partial != NULL &&
3571 skb_peek(&sk->write_queue) == NULL && sk->send_head == NULL)
3572 {3573 flag |= 1;
3574 tcp_send_partial(sk);
3575 }3576
3577 /*3578 * In the LAST_ACK case, the other end FIN'd us. We then FIN'd them, and3579 * we are now waiting for an acknowledge to our FIN. The other end is3580 * already in TIME_WAIT.3581 *3582 * Move to TCP_CLOSE on success.3583 */3584
3585 if (sk->state == TCP_LAST_ACK)
3586 {3587 if (!sk->dead)
3588 sk->state_change(sk);
3589 if(sk->debug)
3590 printk("rcv_ack_seq: %X==%X, acked_seq: %X==%X\n",
3591 sk->rcv_ack_seq,sk->write_seq,sk->acked_seq,sk->fin_seq);
3592 if (sk->rcv_ack_seq == sk->write_seq/*&& sk->acked_seq == sk->fin_seq*/)
3593 {3594 flag |= 1;
3595 tcp_set_state(sk,TCP_CLOSE);
3596 sk->shutdown = SHUTDOWN_MASK;
3597 }3598 }3599
3600 /*3601 * Incoming ACK to a FIN we sent in the case of our initiating the close.3602 *3603 * Move to FIN_WAIT2 to await a FIN from the other end. Set3604 * SEND_SHUTDOWN but not RCV_SHUTDOWN as data can still be coming in.3605 */3606
3607 if (sk->state == TCP_FIN_WAIT1)
3608 {3609
3610 if (!sk->dead)
3611 sk->state_change(sk);
3612 if (sk->rcv_ack_seq == sk->write_seq)
3613 {3614 flag |= 1;
3615 sk->shutdown |= SEND_SHUTDOWN;
3616 tcp_set_state(sk, TCP_FIN_WAIT2);
3617 }3618 }3619
3620 /*3621 * Incoming ACK to a FIN we sent in the case of a simultaneous close.3622 *3623 * Move to TIME_WAIT3624 */3625
3626 if (sk->state == TCP_CLOSING)
3627 {3628
3629 if (!sk->dead)
3630 sk->state_change(sk);
3631 if (sk->rcv_ack_seq == sk->write_seq)
3632 {3633 flag |= 1;
3634 tcp_time_wait(sk);
3635 }3636 }3637
3638 /*3639 * Final ack of a three way shake 3640 */3641
3642 if(sk->state==TCP_SYN_RECV)
3643 {3644 tcp_set_state(sk, TCP_ESTABLISHED);
3645 tcp_options(sk,th);
3646 sk->dummy_th.dest=th->source;
3647 sk->copied_seq = sk->acked_seq;
3648 if(!sk->dead)
3649 sk->state_change(sk);
3650 if(sk->max_window==0)
3651 {3652 sk->max_window=32; /* Sanity check */3653 sk->mss=min(sk->max_window,sk->mtu);
3654 }3655 }3656
3657 /*3658 * I make no guarantees about the first clause in the following3659 * test, i.e. "(!flag) || (flag&4)". I'm not entirely sure under3660 * what conditions "!flag" would be true. However I think the rest3661 * of the conditions would prevent that from causing any3662 * unnecessary retransmission. 3663 * Clearly if the first packet has expired it should be 3664 * retransmitted. The other alternative, "flag&2 && retransmits", is3665 * harder to explain: You have to look carefully at how and when the3666 * timer is set and with what timeout. The most recent transmission always3667 * sets the timer. So in general if the most recent thing has timed3668 * out, everything before it has as well. So we want to go ahead and3669 * retransmit some more. If we didn't explicitly test for this3670 * condition with "flag&2 && retransmits", chances are "when + rto < jiffies"3671 * would not be true. If you look at the pattern of timing, you can3672 * show that rto is increased fast enough that the next packet would3673 * almost never be retransmitted immediately. Then you'd end up3674 * waiting for a timeout to send each packet on the retransmission3675 * queue. With my implementation of the Karn sampling algorithm,3676 * the timeout would double each time. The net result is that it would3677 * take a hideous amount of time to recover from a single dropped packet.3678 * It's possible that there should also be a test for TIME_WRITE, but3679 * I think as long as "send_head != NULL" and "retransmit" is on, we've3680 * got to be in real retransmission mode.3681 * Note that tcp_do_retransmit is called with all==1. Setting cong_window3682 * back to 1 at the timeout will cause us to send 1, then 2, etc. packets.3683 * As long as no further losses occur, this seems reasonable.3684 */3685
3686 if (((!flag) || (flag&4)) && sk->send_head != NULL &&
3687 (((flag&2) && sk->retransmits) ||
3688 (sk->send_head->when + sk->rto < jiffies)))
3689 {3690 if(sk->send_head->when + sk->rto < jiffies)
3691 tcp_retransmit(sk,0);
3692 else3693 {3694 tcp_do_retransmit(sk, 1);
3695 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
3696 }3697 }3698
3699 return(1);
3700 }3701
3702
3703 /*3704 * Process the FIN bit. This now behaves as it is supposed to work3705 * and the FIN takes effect when it is validly part of sequence3706 * space. Not before when we get holes.3707 *3708 * If we are ESTABLISHED, a received fin moves us to CLOSE-WAIT3709 * (and thence onto LAST-ACK and finally, CLOSE, we never enter3710 * TIME-WAIT)3711 *3712 * If we are in FINWAIT-1, a received FIN indicates simultaneous3713 * close and we go into CLOSING (and later onto TIME-WAIT)3714 *3715 * If we are in FINWAIT-2, a received FIN moves us to TIME-WAIT.3716 *3717 */3718
3719 staticinttcp_fin(structsk_buff *skb, structsock *sk, structtcphdr *th)
/* */3720 {3721 sk->fin_seq = th->seq + skb->len + th->syn + th->fin;
3722
3723 if (!sk->dead)
3724 {3725 sk->state_change(sk);
3726 sock_wake_async(sk->socket, 1);
3727 }3728
3729 switch(sk->state)
3730 {3731 caseTCP_SYN_RECV:
3732 caseTCP_SYN_SENT:
3733 caseTCP_ESTABLISHED:
3734 /*3735 * move to CLOSE_WAIT, tcp_data() already handled3736 * sending the ack.3737 */3738 tcp_set_state(sk,TCP_CLOSE_WAIT);
3739 if (th->rst)
3740 sk->shutdown = SHUTDOWN_MASK;
3741 break;
3742
3743 caseTCP_CLOSE_WAIT:
3744 caseTCP_CLOSING:
3745 /*3746 * received a retransmission of the FIN, do3747 * nothing.3748 */3749 break;
3750 caseTCP_TIME_WAIT:
3751 /*3752 * received a retransmission of the FIN,3753 * restart the TIME_WAIT timer.3754 */3755 reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
3756 return(0);
3757 caseTCP_FIN_WAIT1:
3758 /*3759 * This case occurs when a simultaneous close3760 * happens, we must ack the received FIN and3761 * enter the CLOSING state.3762 *3763 * This causes a WRITE timeout, which will either3764 * move on to TIME_WAIT when we timeout, or resend3765 * the FIN properly (maybe we get rid of that annoying3766 * FIN lost hang). The TIME_WRITE code is already correct3767 * for handling this timeout.3768 */3769
3770 if(sk->ip_xmit_timeout != TIME_WRITE)
3771 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
3772 tcp_set_state(sk,TCP_CLOSING);
3773 break;
3774 caseTCP_FIN_WAIT2:
3775 /*3776 * received a FIN -- send ACK and enter TIME_WAIT3777 */3778 reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
3779 sk->shutdown|=SHUTDOWN_MASK;
3780 tcp_set_state(sk,TCP_TIME_WAIT);
3781 break;
3782 caseTCP_CLOSE:
3783 /*3784 * already in CLOSE3785 */3786 break;
3787 default:
3788 tcp_set_state(sk,TCP_LAST_ACK);
3789
3790 /* Start the timers. */3791 reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
3792 return(0);
3793 }3794
3795 return(0);
3796 }3797
3798
3799
3800 /*3801 * This routine handles the data. If there is room in the buffer,3802 * it will be have already been moved into it. If there is no3803 * room, then we will just have to discard the packet.3804 */3805
3806 extern__inline__inttcp_data(structsk_buff *skb, structsock *sk,
/* */3807 unsignedlongsaddr, unsignedshortlen)
3808 {3809 structsk_buff *skb1, *skb2;
3810 structtcphdr *th;
3811 intdup_dumped=0;
3812 u32new_seq, shut_seq;
3813
3814 th = skb->h.th;
3815 skb_pull(skb,th->doff*4);
3816 skb_trim(skb,len-(th->doff*4));
3817
3818 /*3819 * The bytes in the receive read/assembly queue has increased. Needed for the3820 * low memory discard algorithm 3821 */3822
3823 sk->bytes_rcv += skb->len;
3824
3825 if (skb->len == 0 && !th->fin)
3826 {3827 /* 3828 * Don't want to keep passing ack's back and forth. 3829 * (someone sent us dataless, boring frame)3830 */3831 if (!th->ack)
3832 tcp_send_ack(sk->sent_seq, sk->acked_seq,sk, th, saddr);
3833 kfree_skb(skb, FREE_READ);
3834 return(0);
3835 }3836
3837 /*3838 * We no longer have anyone receiving data on this connection.3839 */3840
3841 #ifndef TCP_DONT_RST_SHUTDOWN
3842
3843 if(sk->shutdown & RCV_SHUTDOWN)
3844 {3845 /*3846 * FIXME: BSD has some magic to avoid sending resets to3847 * broken 4.2 BSD keepalives. Much to my surprise a few non3848 * BSD stacks still have broken keepalives so we want to3849 * cope with it.3850 */3851
3852 if(skb->len) /* We don't care if it's just an ack or3853 a keepalive/window probe */3854 {3855 new_seq= th->seq + skb->len + th->syn; /* Right edge of _data_ part of frame */3856
3857 /* Do this the way 4.4BSD treats it. Not what I'd3858 regard as the meaning of the spec but it's what BSD3859 does and clearly they know everything 8) */3860
3861 /*3862 * This is valid because of two things3863 *3864 * a) The way tcp_data behaves at the bottom.3865 * b) A fin takes effect when read not when received.3866 */3867
3868 shut_seq=sk->acked_seq+1; /* Last byte */3869
3870 if(after(new_seq,shut_seq))
3871 {3872 if(sk->debug)
3873 printk("Data arrived on %p after close [Data right edge %X, Socket shut on %X] %d\n",
3874 sk, new_seq, shut_seq, sk->blog);
3875 if(sk->dead)
3876 {3877 sk->acked_seq = new_seq + th->fin;
3878 tcp_reset(sk->saddr, sk->daddr, skb->h.th,
3879 sk->prot, NULL, skb->dev, sk->ip_tos, sk->ip_ttl);
3880 tcp_statistics.TcpEstabResets++;
3881 tcp_set_state(sk,TCP_CLOSE);
3882 sk->err = EPIPE;
3883 sk->shutdown = SHUTDOWN_MASK;
3884 kfree_skb(skb, FREE_READ);
3885 return 0;
3886 }3887 }3888 }3889 }3890
3891 #endif3892
3893 /*3894 * Now we have to walk the chain, and figure out where this one3895 * goes into it. This is set up so that the last packet we received3896 * will be the first one we look at, that way if everything comes3897 * in order, there will be no performance loss, and if they come3898 * out of order we will be able to fit things in nicely.3899 *3900 * [AC: This is wrong. We should assume in order first and then walk3901 * forwards from the first hole based upon real traffic patterns.]3902 * 3903 */3904
3905 if (skb_peek(&sk->receive_queue) == NULL) /* Empty queue is easy case */3906 {3907 skb_queue_head(&sk->receive_queue,skb);
3908 skb1= NULL;
3909 }3910 else3911 {3912 for(skb1=sk->receive_queue.prev; ; skb1 = skb1->prev)
3913 {3914 if(sk->debug)
3915 {3916 printk("skb1=%p :", skb1);
3917 printk("skb1->h.th->seq = %d: ", skb1->h.th->seq);
3918 printk("skb->h.th->seq = %d\n",skb->h.th->seq);
3919 printk("copied_seq = %d acked_seq = %d\n", sk->copied_seq,
3920 sk->acked_seq);
3921 }3922
3923 /*3924 * Optimisation: Duplicate frame or extension of previous frame from3925 * same sequence point (lost ack case).3926 * The frame contains duplicate data or replaces a previous frame3927 * discard the previous frame (safe as sk->inuse is set) and put3928 * the new one in its place.3929 */3930
3931 if (th->seq==skb1->h.th->seq && skb->len>= skb1->len)
3932 {3933 skb_append(skb1,skb);
3934 skb_unlink(skb1);
3935 kfree_skb(skb1,FREE_READ);
3936 dup_dumped=1;
3937 skb1=NULL;
3938 break;
3939 }3940
3941 /*3942 * Found where it fits3943 */3944
3945 if (after(th->seq+1, skb1->h.th->seq))
3946 {3947 skb_append(skb1,skb);
3948 break;
3949 }3950
3951 /*3952 * See if we've hit the start. If so insert.3953 */3954 if (skb1 == skb_peek(&sk->receive_queue))
3955 {3956 skb_queue_head(&sk->receive_queue, skb);
3957 break;
3958 }3959 }3960 }3961
3962 /*3963 * Figure out what the ack value for this frame is3964 */3965
3966 th->ack_seq = th->seq + skb->len;
3967 if (th->syn)
3968 th->ack_seq++;
3969 if (th->fin)
3970 th->ack_seq++;
3971
3972 if (before(sk->acked_seq, sk->copied_seq))
3973 {3974 printk("*** tcp.c:tcp_data bug acked < copied\n");
3975 sk->acked_seq = sk->copied_seq;
3976 }3977
3978 /*3979 * Now figure out if we can ack anything. This is very messy because we really want two3980 * receive queues, a completed and an assembly queue. We also want only one transmit3981 * queue.3982 */3983
3984 if ((!dup_dumped && (skb1 == NULL || skb1->acked)) || before(th->seq, sk->acked_seq+1))
3985 {3986 if (before(th->seq, sk->acked_seq+1))
3987 {3988 intnewwindow;
3989
3990 if (after(th->ack_seq, sk->acked_seq))
3991 {3992 newwindow = sk->window-(th->ack_seq - sk->acked_seq);
3993 if (newwindow < 0)
3994 newwindow = 0;
3995 sk->window = newwindow;
3996 sk->acked_seq = th->ack_seq;
3997 }3998 skb->acked = 1;
3999
4000 /*4001 * When we ack the fin, we do the FIN 4002 * processing.4003 */4004
4005 if (skb->h.th->fin)
4006 {4007 tcp_fin(skb,sk,skb->h.th);
4008 }4009
4010 for(skb2 = skb->next;
4011 skb2 != (structsk_buff *)&sk->receive_queue;
4012 skb2 = skb2->next)
4013 {4014 if (before(skb2->h.th->seq, sk->acked_seq+1))
4015 {4016 if (after(skb2->h.th->ack_seq, sk->acked_seq))
4017 {4018 newwindow = sk->window -
4019 (skb2->h.th->ack_seq - sk->acked_seq);
4020 if (newwindow < 0)
4021 newwindow = 0;
4022 sk->window = newwindow;
4023 sk->acked_seq = skb2->h.th->ack_seq;
4024 }4025 skb2->acked = 1;
4026 /*4027 * When we ack the fin, we do4028 * the fin handling.4029 */4030 if (skb2->h.th->fin)
4031 {4032 tcp_fin(skb,sk,skb->h.th);
4033 }4034
4035 /*4036 * Force an immediate ack.4037 */4038
4039 sk->ack_backlog = sk->max_ack_backlog;
4040 }4041 else4042 {4043 break;
4044 }4045 }4046
4047 /*4048 * This also takes care of updating the window.4049 * This if statement needs to be simplified.4050 */4051 if (!sk->delay_acks ||
4052 sk->ack_backlog >= sk->max_ack_backlog ||
4053 sk->bytes_rcv > sk->max_unacked || th->fin) {4054 /* tcp_send_ack(sk->sent_seq, sk->acked_seq,sk,th, saddr); */4055 }4056 else4057 {4058 sk->ack_backlog++;
4059 if(sk->debug)
4060 printk("Ack queued.\n");
4061 reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
4062 }4063 }4064 }4065
4066 /*4067 * If we've missed a packet, send an ack.4068 * Also start a timer to send another.4069 */4070
4071 if (!skb->acked)
4072 {4073
4074 /*4075 * This is important. If we don't have much room left,4076 * we need to throw out a few packets so we have a good4077 * window. Note that mtu is used, not mss, because mss is really4078 * for the send side. He could be sending us stuff as large as mtu.4079 */4080
4081 while (sk->prot->rspace(sk) < sk->mtu)
4082 {4083 skb1 = skb_peek(&sk->receive_queue);
4084 if (skb1 == NULL)
4085 {4086 printk("INET: tcp.c:tcp_data memory leak detected.\n");
4087 break;
4088 }4089
4090 /*4091 * Don't throw out something that has been acked. 4092 */4093
4094 if (skb1->acked)
4095 {4096 break;
4097 }4098
4099 skb_unlink(skb1);
4100 kfree_skb(skb1, FREE_READ);
4101 }4102 tcp_send_ack(sk->sent_seq, sk->acked_seq, sk, th, saddr);
4103 sk->ack_backlog++;
4104 reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
4105 }4106 else4107 {4108 tcp_send_ack(sk->sent_seq, sk->acked_seq, sk, th, saddr);
4109 }4110
4111 /*4112 * Now tell the user we may have some data. 4113 */4114
4115 if (!sk->dead)
4116 {4117 if(sk->debug)
4118 printk("Data wakeup.\n");
4119 sk->data_ready(sk,0);
4120 }4121 return(0);
4122 }4123
4124
4125 /*4126 * This routine is only called when we have urgent data4127 * signalled. Its the 'slow' part of tcp_urg. It could be4128 * moved inline now as tcp_urg is only called from one4129 * place. We handle URGent data wrong. We have to - as4130 * BSD still doesn't use the correction from RFC961.4131 */4132
4133 staticvoidtcp_check_urg(structsock * sk, structtcphdr * th)
/* */4134 {4135 u32ptr = ntohs(th->urg_ptr);
4136
4137 if (ptr)
4138 ptr--;
4139 ptr += th->seq;
4140
4141 /* ignore urgent data that we've already seen and read */4142 if (after(sk->copied_seq, ptr))
4143 return;
4144
4145 /* do we already have a newer (or duplicate) urgent pointer? */4146 if (sk->urg_data && !after(ptr, sk->urg_seq))
4147 return;
4148
4149 /* tell the world about our new urgent pointer */4150 if (sk->proc != 0) {4151 if (sk->proc > 0) {4152 kill_proc(sk->proc, SIGURG, 1);
4153 }else{4154 kill_pg(-sk->proc, SIGURG, 1);
4155 }4156 }4157 sk->urg_data = URG_NOTYET;
4158 sk->urg_seq = ptr;
4159 }4160
4161 /*4162 * This is the 'fast' part of urgent handling.4163 */4164
4165 extern__inline__inttcp_urg(structsock *sk, structtcphdr *th,
/* */4166 unsignedlongsaddr, unsignedlonglen)
4167 {4168 u32ptr;
4169
4170 /*4171 * Check if we get a new urgent pointer - normally not 4172 */4173
4174 if (th->urg)
4175 tcp_check_urg(sk,th);
4176
4177 /*4178 * Do we wait for any urgent data? - normally not4179 */4180
4181 if (sk->urg_data != URG_NOTYET)
4182 return 0;
4183
4184 /*4185 * Is the urgent pointer pointing into this packet? 4186 */4187
4188 ptr = sk->urg_seq - th->seq + th->doff*4;
4189 if (ptr >= len)
4190 return 0;
4191
4192 /*4193 * Ok, got the correct packet, update info 4194 */4195
4196 sk->urg_data = URG_VALID | *(ptr + (unsignedchar *) th);
4197 if (!sk->dead)
4198 sk->data_ready(sk,0);
4199 return 0;
4200 }4201
4202 /*4203 * This will accept the next outstanding connection. 4204 */4205
4206 staticstructsock *tcp_accept(structsock *sk, intflags)
/* */4207 {4208 structsock *newsk;
4209 structsk_buff *skb;
4210
4211 /*4212 * We need to make sure that this socket is listening,4213 * and that it has something pending.4214 */4215
4216 if (sk->state != TCP_LISTEN)
4217 {4218 sk->err = EINVAL;
4219 return(NULL);
4220 }4221
4222 /* Avoid the race. */4223 cli();
4224 sk->inuse = 1;
4225
4226 while((skb = tcp_dequeue_established(sk)) == NULL)
4227 {4228 if (flags & O_NONBLOCK)
4229 {4230 sti();
4231 release_sock(sk);
4232 sk->err = EAGAIN;
4233 return(NULL);
4234 }4235
4236 release_sock(sk);
4237 interruptible_sleep_on(sk->sleep);
4238 if (current->signal & ~current->blocked)
4239 {4240 sti();
4241 sk->err = ERESTARTSYS;
4242 return(NULL);
4243 }4244 sk->inuse = 1;
4245 }4246 sti();
4247
4248 /*4249 * Now all we need to do is return skb->sk. 4250 */4251
4252 newsk = skb->sk;
4253
4254 kfree_skb(skb, FREE_READ);
4255 sk->ack_backlog--;
4256 release_sock(sk);
4257 return(newsk);
4258 }4259
4260
4261 /*4262 * This will initiate an outgoing connection. 4263 */4264
4265 staticinttcp_connect(structsock *sk, structsockaddr_in *usin, intaddr_len)
/* */4266 {4267 structsk_buff *buff;
4268 structdevice *dev=NULL;
4269 unsignedchar *ptr;
4270 inttmp;
4271 intatype;
4272 structtcphdr *t1;
4273 structrtable *rt;
4274
4275 if (sk->state != TCP_CLOSE)
4276 {4277 return(-EISCONN);
4278 }4279
4280 if (addr_len < 8)
4281 return(-EINVAL);
4282
4283 if (usin->sin_family && usin->sin_family != AF_INET)
4284 return(-EAFNOSUPPORT);
4285
4286 /*4287 * connect() to INADDR_ANY means loopback (BSD'ism).4288 */4289
4290 if(usin->sin_addr.s_addr==INADDR_ANY)
4291 usin->sin_addr.s_addr=ip_my_addr();
4292
4293 /*4294 * Don't want a TCP connection going to a broadcast address 4295 */4296
4297 if ((atype=ip_chk_addr(usin->sin_addr.s_addr)) == IS_BROADCAST || atype==IS_MULTICAST)
4298 return -ENETUNREACH;
4299
4300 sk->inuse = 1;
4301 sk->daddr = usin->sin_addr.s_addr;
4302 sk->write_seq = tcp_init_seq();
4303 sk->window_seq = sk->write_seq;
4304 sk->rcv_ack_seq = sk->write_seq -1;
4305 sk->err = 0;
4306 sk->dummy_th.dest = usin->sin_port;
4307 release_sock(sk);
4308
4309 buff = sk->prot->wmalloc(sk,MAX_SYN_SIZE,0, GFP_KERNEL);
4310 if (buff == NULL)
4311 {4312 return(-ENOMEM);
4313 }4314 sk->inuse = 1;
4315 buff->sk = sk;
4316 buff->free = 0;
4317 buff->localroute = sk->localroute;
4318
4319
4320 /*4321 * Put in the IP header and routing stuff. 4322 */4323
4324 rt=ip_rt_route(sk->daddr, NULL, NULL);
4325
4326
4327 /*4328 * We need to build the routing stuff from the things saved in skb. 4329 */4330
4331 tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
4332 IPPROTO_TCP, NULL, MAX_SYN_SIZE,sk->ip_tos,sk->ip_ttl);
4333 if (tmp < 0)
4334 {4335 sk->prot->wfree(sk, buff);
4336 release_sock(sk);
4337 return(-ENETUNREACH);
4338 }4339
4340 t1 = (structtcphdr *) skb_put(buff,sizeof(structtcphdr));
4341
4342 memcpy(t1,(void *)&(sk->dummy_th), sizeof(*t1));
4343 t1->seq = ntohl(sk->write_seq++);
4344 sk->sent_seq = sk->write_seq;
4345 buff->h.seq = sk->write_seq;
4346 t1->ack = 0;
4347 t1->window = 2;
4348 t1->res1=0;
4349 t1->res2=0;
4350 t1->rst = 0;
4351 t1->urg = 0;
4352 t1->psh = 0;
4353 t1->syn = 1;
4354 t1->urg_ptr = 0;
4355 t1->doff = 6;
4356 /* use 512 or whatever user asked for */4357
4358 if(rt!=NULL && (rt->rt_flags&RTF_WINDOW))
4359 sk->window_clamp=rt->rt_window;
4360 else4361 sk->window_clamp=0;
4362
4363 if (sk->user_mss)
4364 sk->mtu = sk->user_mss;
4365 elseif(rt!=NULL && (rt->rt_flags&RTF_MTU))
4366 sk->mtu = rt->rt_mss;
4367 else4368 {4369 #ifdefCONFIG_INET_SNARL4370 if ((sk->saddr ^ sk->daddr) & default_mask(sk->saddr))
4371 #else4372 if ((sk->saddr ^ sk->daddr) & dev->pa_mask)
4373 #endif4374 sk->mtu = 576 - HEADER_SIZE;
4375 else4376 sk->mtu = MAX_WINDOW;
4377 }4378 /*4379 * but not bigger than device MTU 4380 */4381
4382 if(sk->mtu <32)
4383 sk->mtu = 32; /* Sanity limit */4384
4385 sk->mtu = min(sk->mtu, dev->mtu - HEADER_SIZE);
4386
4387 /*4388 * Put in the TCP options to say MTU. 4389 */4390
4391 ptr = skb_put(buff,4);
4392 ptr[0] = 2;
4393 ptr[1] = 4;
4394 ptr[2] = (sk->mtu) >> 8;
4395 ptr[3] = (sk->mtu) & 0xff;
4396 tcp_send_check(t1, sk->saddr, sk->daddr,
4397 sizeof(structtcphdr) + 4, sk);
4398
4399 /*4400 * This must go first otherwise a really quick response will get reset. 4401 */4402
4403 tcp_cache_zap();
4404 tcp_set_state(sk,TCP_SYN_SENT);
4405 if(rt&&rt->rt_flags&RTF_IRTT)
4406 sk->rto = rt->rt_irtt;
4407 else4408 sk->rto = TCP_TIMEOUT_INIT;
4409 sk->retransmit_timer.function=&retransmit_timer;
4410 sk->retransmit_timer.data = (unsignedlong)sk;
4411 reset_xmit_timer(sk, TIME_WRITE, sk->rto); /* Timer for repeating the SYN until an answer */4412 sk->retransmits = 0; /* Now works the right way instead of a hacked initial setting */4413
4414 sk->prot->queue_xmit(sk, dev, buff, 0);
4415 reset_xmit_timer(sk, TIME_WRITE, sk->rto);
4416 tcp_statistics.TcpActiveOpens++;
4417 tcp_statistics.TcpOutSegs++;
4418
4419 release_sock(sk);
4420 return(0);
4421 }4422
4423
4424 /* This functions checks to see if the tcp header is actually acceptable. */4425 extern__inline__inttcp_sequence(structsock *sk, structtcphdr *th, shortlen,
/* */4426 structoptions *opt, unsignedlongsaddr, structdevice *dev)
4427 {4428 u32next_seq;
4429
4430 next_seq = len - 4*th->doff;
4431 if (th->fin)
4432 next_seq++;
4433 /* if we have a zero window, we can't have any data in the packet.. */4434 if (next_seq && !sk->window)
4435 gotoignore_it;
4436 next_seq += th->seq;
4437
4438 /*4439 * This isn't quite right. sk->acked_seq could be more recent4440 * than sk->window. This is however close enough. We will accept4441 * slightly more packets than we should, but it should not cause4442 * problems unless someone is trying to forge packets.4443 */4444
4445 /* have we already seen all of this packet? */4446 if (!after(next_seq+1, sk->acked_seq))
4447 gotoignore_it;
4448 /* or does it start beyond the window? */4449 if (!before(th->seq, sk->acked_seq + sk->window + 1))
4450 gotoignore_it;
4451
4452 /* ok, at least part of this packet would seem interesting.. */4453 return 1;
4454
4455 ignore_it:
4456 if (th->rst)
4457 return 0;
4458
4459 /*4460 * Send a reset if we get something not ours and we are4461 * unsynchronized. Note: We don't do anything to our end. We4462 * are just killing the bogus remote connection then we will4463 * connect again and it will work (with luck).4464 */4465
4466 if (sk->state==TCP_SYN_SENT || sk->state==TCP_SYN_RECV)
4467 {4468 tcp_reset(sk->saddr,sk->daddr,th,sk->prot,NULL,dev, sk->ip_tos,sk->ip_ttl);
4469 return 1;
4470 }4471
4472 /* Try to resync things. */4473 tcp_send_ack(sk->sent_seq, sk->acked_seq, sk, th, saddr);
4474 return 0;
4475 }4476
4477 /*4478 * When we get a reset we do this.4479 */4480
4481 staticinttcp_std_reset(structsock *sk, structsk_buff *skb)
/* */4482 {4483 sk->zapped = 1;
4484 sk->err = ECONNRESET;
4485 if (sk->state == TCP_SYN_SENT)
4486 sk->err = ECONNREFUSED;
4487 if (sk->state == TCP_CLOSE_WAIT)
4488 sk->err = EPIPE;
4489 #ifdef TCP_DO_RFC1337
4490 /*4491 * Time wait assassination protection [RFC1337]4492 */4493 if(sk->state!=TCP_TIME_WAIT)
4494 {4495 tcp_set_state(sk,TCP_CLOSE);
4496 sk->shutdown = SHUTDOWN_MASK;
4497 }4498 #else4499 tcp_set_state(sk,TCP_CLOSE);
4500 sk->shutdown = SHUTDOWN_MASK;
4501 #endif4502 if (!sk->dead)
4503 sk->state_change(sk);
4504 kfree_skb(skb, FREE_READ);
4505 release_sock(sk);
4506 return(0);
4507 }4508
4509 /*4510 * A TCP packet has arrived.4511 * skb->h.raw is the TCP header.4512 */4513
4514 inttcp_rcv(structsk_buff *skb, structdevice *dev, structoptions *opt,
/* */4515 unsignedlongdaddr, unsignedshortlen,
4516 unsignedlongsaddr, intredo, structinet_protocol * protocol)
4517 {4518 structtcphdr *th;
4519 structsock *sk;
4520 intsyn_ok=0;
4521
4522 tcp_statistics.TcpInSegs++;
4523 if(skb->pkt_type!=PACKET_HOST)
4524 {4525 kfree_skb(skb,FREE_READ);
4526 return(0);
4527 }4528
4529 th = skb->h.th;
4530
4531 /*4532 * Find the socket, using the last hit cache if applicable.4533 */4534
4535 if(saddr==th_cache_saddr && daddr==th_cache_daddr && th->dest==th_cache_dport && th->source==th_cache_sport)
4536 sk=(structsock *)th_cache_sk;
4537 else4538 {4539 sk = get_sock(&tcp_prot, th->dest, saddr, th->source, daddr);
4540 th_cache_saddr=saddr;
4541 th_cache_daddr=daddr;
4542 th_cache_dport=th->dest;
4543 th_cache_sport=th->source;
4544 th_cache_sk=sk;
4545 }4546
4547 /*4548 * If this socket has got a reset it's to all intents and purposes 4549 * really dead. Count closed sockets as dead.4550 *4551 * Note: BSD appears to have a bug here. A 'closed' TCP in BSD4552 * simply drops data. This seems incorrect as a 'closed' TCP doesn't4553 * exist so should cause resets as if the port was unreachable.4554 */4555
4556 if (sk!=NULL && (sk->zapped || sk->state==TCP_CLOSE))
4557 sk=NULL;
4558
4559 if (!redo)
4560 {4561 /*4562 * Pull up the IP header.4563 */4564 skb_pull(skb, skb->h.raw-skb->data);
4565 /*4566 * Try to use the device checksum if provided.4567 */4568 if (
4569 (skb->ip_summed && tcp_check(th, len, saddr, daddr, skb->csum ))||
4570 (!skb->ip_summed && tcp_check(th, len, saddr, daddr, csum_partial((char *)th, len, 0)))
4571 )
4572 {4573 skb->sk = NULL;
4574 kfree_skb(skb,FREE_READ);
4575 /*4576 * We don't release the socket because it was4577 * never marked in use.4578 */4579 return(0);
4580 }4581 th->seq = ntohl(th->seq);
4582
4583 /* See if we know about the socket. */4584 if (sk == NULL)
4585 {4586 /*4587 * No such TCB. If th->rst is 0 send a reset (checked in tcp_reset)4588 */4589 tcp_reset(daddr, saddr, th, &tcp_prot, opt,dev,skb->ip_hdr->tos,255);
4590 skb->sk = NULL;
4591 /*4592 * Discard frame4593 */4594 kfree_skb(skb, FREE_READ);
4595 return(0);
4596 }4597
4598 /* skb->len = len;*/4599 skb->acked = 0;
4600 skb->used = 0;
4601 skb->free = 0;
4602 skb->saddr = daddr;
4603 skb->daddr = saddr;
4604
4605 /* We may need to add it to the backlog here. */4606 cli();
4607 if (sk->inuse)
4608 {4609 skb_queue_tail(&sk->back_log, skb);
4610 sti();
4611 return(0);
4612 }4613 sk->inuse = 1;
4614 sti();
4615 }4616 else4617 {4618 if (sk==NULL)
4619 {4620 tcp_reset(daddr, saddr, th, &tcp_prot, opt,dev,skb->ip_hdr->tos,255);
4621 skb->sk = NULL;
4622 kfree_skb(skb, FREE_READ);
4623 return(0);
4624 }4625 }4626
4627
4628 if (!sk->prot)
4629 {4630 printk("IMPOSSIBLE 3\n");
4631 return(0);
4632 }4633
4634
4635 /*4636 * Charge the memory to the socket. 4637 */4638
4639 if (sk->rmem_alloc + skb->truesize >= sk->rcvbuf)
4640 {4641 kfree_skb(skb, FREE_READ);
4642 release_sock(sk);
4643 return(0);
4644 }4645
4646 skb->sk=sk;
4647 sk->rmem_alloc += skb->truesize;
4648
4649 /*4650 * This basically follows the flow suggested by RFC793, with the corrections in RFC1122. We4651 * don't implement precedence and we process URG incorrectly (deliberately so) for BSD bug4652 * compatibility. We also set up variables more thoroughly [Karn notes in the4653 * KA9Q code the RFC793 incoming segment rules don't initialise the variables for all paths].4654 */4655
4656 if(sk->state!=TCP_ESTABLISHED) /* Skip this lot for normal flow */4657 {4658
4659 /*4660 * Now deal with unusual cases.4661 */4662
4663 if(sk->state==TCP_LISTEN)
4664 {4665 if(th->ack) /* These use the socket TOS.. might want to be the received TOS */4666 tcp_reset(daddr,saddr,th,sk->prot,opt,dev,sk->ip_tos, sk->ip_ttl);
4667
4668 /*4669 * We don't care for RST, and non SYN are absorbed (old segments)4670 * Broadcast/multicast SYN isn't allowed. Note - bug if you change the4671 * netmask on a running connection it can go broadcast. Even Sun's have4672 * this problem so I'm ignoring it 4673 */4674
4675 if(th->rst || !th->syn || th->ack || ip_chk_addr(daddr)!=IS_MYADDR)
4676 {4677 kfree_skb(skb, FREE_READ);
4678 release_sock(sk);
4679 return 0;
4680 }4681
4682 /* 4683 * Guess we need to make a new socket up 4684 */4685
4686 tcp_conn_request(sk, skb, daddr, saddr, opt, dev, tcp_init_seq());
4687
4688 /*4689 * Now we have several options: In theory there is nothing else4690 * in the frame. KA9Q has an option to send data with the syn,4691 * BSD accepts data with the syn up to the [to be] advertised window4692 * and Solaris 2.1 gives you a protocol error. For now we just ignore4693 * it, that fits the spec precisely and avoids incompatibilities. It4694 * would be nice in future to drop through and process the data.4695 */4696
4697 release_sock(sk);
4698 return 0;
4699 }4700
4701 /* retransmitted SYN? */4702 if (sk->state == TCP_SYN_RECV && th->syn && th->seq+1 == sk->acked_seq)
4703 {4704 kfree_skb(skb, FREE_READ);
4705 release_sock(sk);
4706 return 0;
4707 }4708
4709 /*4710 * SYN sent means we have to look for a suitable ack and either reset4711 * for bad matches or go to connected 4712 */4713
4714 if(sk->state==TCP_SYN_SENT)
4715 {4716 /* Crossed SYN or previous junk segment */4717 if(th->ack)
4718 {4719 /* We got an ack, but it's not a good ack */4720 if(!tcp_ack(sk,th,saddr,len))
4721 {4722 /* Reset the ack - its an ack from a 4723 different connection [ th->rst is checked in tcp_reset()] */4724 tcp_statistics.TcpAttemptFails++;
4725 tcp_reset(daddr, saddr, th,
4726 sk->prot, opt,dev,sk->ip_tos,sk->ip_ttl);
4727 kfree_skb(skb, FREE_READ);
4728 release_sock(sk);
4729 return(0);
4730 }4731 if(th->rst)
4732 returntcp_std_reset(sk,skb);
4733 if(!th->syn)
4734 {4735 /* A valid ack from a different connection4736 start. Shouldn't happen but cover it */4737 kfree_skb(skb, FREE_READ);
4738 release_sock(sk);
4739 return 0;
4740 }4741 /*4742 * Ok.. it's good. Set up sequence numbers and4743 * move to established.4744 */4745 syn_ok=1; /* Don't reset this connection for the syn */4746 sk->acked_seq=th->seq+1;
4747 sk->fin_seq=th->seq;
4748 tcp_send_ack(sk->sent_seq,sk->acked_seq,sk,th,sk->daddr);
4749 tcp_set_state(sk, TCP_ESTABLISHED);
4750 tcp_options(sk,th);
4751 sk->dummy_th.dest=th->source;
4752 sk->copied_seq = sk->acked_seq;
4753 if(!sk->dead)
4754 {4755 sk->state_change(sk);
4756 sock_wake_async(sk->socket, 0);
4757 }4758 if(sk->max_window==0)
4759 {4760 sk->max_window = 32;
4761 sk->mss = min(sk->max_window, sk->mtu);
4762 }4763 }4764 else4765 {4766 /* See if SYN's cross. Drop if boring */4767 if(th->syn && !th->rst)
4768 {4769 /* Crossed SYN's are fine - but talking to4770 yourself is right out... */4771 if(sk->saddr==saddr && sk->daddr==daddr &&
4772 sk->dummy_th.source==th->source &&
4773 sk->dummy_th.dest==th->dest)
4774 {4775 tcp_statistics.TcpAttemptFails++;
4776 returntcp_std_reset(sk,skb);
4777 }4778 tcp_set_state(sk,TCP_SYN_RECV);
4779
4780 /*4781 * FIXME:4782 * Must send SYN|ACK here4783 */4784 }4785 /* Discard junk segment */4786 kfree_skb(skb, FREE_READ);
4787 release_sock(sk);
4788 return 0;
4789 }4790 /*4791 * SYN_RECV with data maybe.. drop through4792 */4793 gotorfc_step6;
4794 }4795
4796 /*4797 * BSD has a funny hack with TIME_WAIT and fast reuse of a port. There is4798 * a more complex suggestion for fixing these reuse issues in RFC16444799 * but not yet ready for general use. Also see RFC1379.4800 */4801
4802 #defineBSD_TIME_WAIT4803 #ifdefBSD_TIME_WAIT4804 if (sk->state == TCP_TIME_WAIT && th->syn && sk->dead &&
4805 after(th->seq, sk->acked_seq) && !th->rst)
4806 {4807 u32seq = sk->write_seq;
4808 if(sk->debug)
4809 printk("Doing a BSD time wait\n");
4810 tcp_statistics.TcpEstabResets++;
4811 sk->rmem_alloc -= skb->truesize;
4812 skb->sk = NULL;
4813 sk->err=ECONNRESET;
4814 tcp_set_state(sk, TCP_CLOSE);
4815 sk->shutdown = SHUTDOWN_MASK;
4816 release_sock(sk);
4817 sk=get_sock(&tcp_prot, th->dest, saddr, th->source, daddr);
4818 if (sk && sk->state==TCP_LISTEN)
4819 {4820 sk->inuse=1;
4821 skb->sk = sk;
4822 sk->rmem_alloc += skb->truesize;
4823 tcp_conn_request(sk, skb, daddr, saddr,opt, dev,seq+128000);
4824 release_sock(sk);
4825 return 0;
4826 }4827 kfree_skb(skb, FREE_READ);
4828 return 0;
4829 }4830 #endif4831 }4832
4833 /*4834 * We are now in normal data flow (see the step list in the RFC)4835 * Note most of these are inline now. I'll inline the lot when4836 * I have time to test it hard and look at what gcc outputs 4837 */4838
4839 if(!tcp_sequence(sk,th,len,opt,saddr,dev))
4840 {4841 kfree_skb(skb, FREE_READ);
4842 release_sock(sk);
4843 return 0;
4844 }4845
4846 if(th->rst)
4847 returntcp_std_reset(sk,skb);
4848
4849 /*4850 * !syn_ok is effectively the state test in RFC793.4851 */4852
4853 if(th->syn && !syn_ok)
4854 {4855 tcp_reset(daddr,saddr,th, &tcp_prot, opt, dev, skb->ip_hdr->tos, 255);
4856 returntcp_std_reset(sk,skb);
4857 }4858
4859 /*4860 * Process the ACK4861 */4862
4863
4864 if(th->ack && !tcp_ack(sk,th,saddr,len))
4865 {4866 /*4867 * Our three way handshake failed.4868 */4869
4870 if(sk->state==TCP_SYN_RECV)
4871 {4872 tcp_reset(daddr, saddr, th,sk->prot, opt, dev,sk->ip_tos,sk->ip_ttl);
4873 }4874 kfree_skb(skb, FREE_READ);
4875 release_sock(sk);
4876 return 0;
4877 }4878
4879 rfc_step6: /* I'll clean this up later */4880
4881 /*4882 * Process urgent data4883 */4884
4885 if(tcp_urg(sk, th, saddr, len))
4886 {4887 kfree_skb(skb, FREE_READ);
4888 release_sock(sk);
4889 return 0;
4890 }4891
4892
4893 /*4894 * Process the encapsulated data4895 */4896
4897 if(tcp_data(skb,sk, saddr, len))
4898 {4899 kfree_skb(skb, FREE_READ);
4900 release_sock(sk);
4901 return 0;
4902 }4903
4904 /*4905 * And done4906 */4907
4908 release_sock(sk);
4909 return 0;
4910 }4911
4912 /*4913 * This routine sends a packet with an out of date sequence4914 * number. It assumes the other end will try to ack it.4915 */4916
4917 staticvoidtcp_write_wakeup(structsock *sk)
/* */4918 {4919 structsk_buff *buff,*skb;
4920 structtcphdr *t1;
4921 structdevice *dev=NULL;
4922 inttmp;
4923
4924 if (sk->zapped)
4925 return; /* After a valid reset we can send no more */4926
4927 /*4928 * Write data can still be transmitted/retransmitted in the4929 * following states. If any other state is encountered, return.4930 * [listen/close will never occur here anyway]4931 */4932
4933 if (sk->state != TCP_ESTABLISHED &&
4934 sk->state != TCP_CLOSE_WAIT &&
4935 sk->state != TCP_FIN_WAIT1 &&
4936 sk->state != TCP_LAST_ACK &&
4937 sk->state != TCP_CLOSING4938 )
4939 {4940 return;
4941 }4942 if ( before(sk->sent_seq, sk->window_seq) &&
4943 (skb=skb_peek(&sk->write_queue)))
4944 {4945 /*4946 * We are probing the opening of a window4947 * but the window size is != 04948 * must have been a result SWS advoidance ( sender )4949 */4950
4951 structiphdr *iph;
4952 structtcphdr *th;
4953 structtcphdr *nth;
4954 unsignedlongwin_size, ow_size;
4955 void * tcp_data_start;
4956
4957 /*4958 * How many bytes can we send ?4959 */4960
4961 win_size = sk->window_seq - sk->sent_seq;
4962
4963 /*4964 * Recover the buffer pointers4965 */4966
4967 iph = (structiphdr *)(skb->data + skb->dev->hard_header_len);
4968 th = (structtcphdr *)(((char *)iph) +(iph->ihl << 2));
4969
4970 /*4971 * Grab the data for a temporary frame4972 */4973
4974 buff = sk->prot->wmalloc(sk, win_size + th->doff * 4 +
4975 (iph->ihl << 2) +
4976 skb->dev->hard_header_len + 15,
4977 1, GFP_ATOMIC);
4978 if ( buff == NULL )
4979 return;
4980
4981 /* 4982 * If we strip the packet on the write queue we must4983 * be ready to retransmit this one 4984 */4985
4986 buff->free = /*0*/1;
4987
4988 buff->sk = sk;
4989 buff->localroute = sk->localroute;
4990
4991 /*4992 * Put headers on the new packet4993 */4994
4995 tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
4996 IPPROTO_TCP, sk->opt, buff->truesize,
4997 sk->ip_tos,sk->ip_ttl);
4998 if (tmp < 0)
4999 {5000 sk->prot->wfree(sk, buff);
5001 return;
5002 }5003
5004 /*5005 * Move the TCP header over5006 */5007
5008 buff->dev = dev;
5009
5010 nth = (structtcphdr *) skb_put(buff,th->doff*4);
5011
5012 memcpy(nth, th, th->doff * 4);
5013
5014 /*5015 * Correct the new header5016 */5017
5018 nth->ack = 1;
5019 nth->ack_seq = ntohl(sk->acked_seq);
5020 nth->window = ntohs(tcp_select_window(sk));
5021 nth->check = 0;
5022
5023 /*5024 * Find the first data byte.5025 */5026
5027 tcp_data_start = skb->data + skb->dev->hard_header_len +
5028 (iph->ihl << 2) + th->doff * 4;
5029
5030 /*5031 * Add it to our new buffer5032 */5033 memcpy(skb_put(buff,win_size), tcp_data_start, win_size);
5034
5035 /*5036 * Remember our right edge sequence number.5037 */5038
5039 buff->h.seq = sk->sent_seq + win_size;
5040 sk->sent_seq = buff->h.seq; /* Hack */5041 #if 0
5042
5043 /*5044 * now: shrink the queue head segment 5045 */5046
5047 th->check = 0;
5048 ow_size = skb->len - win_size -
5049 ((unsignedlong) (tcp_data_start - (void *) skb->data));
5050
5051 memmove(tcp_data_start, tcp_data_start + win_size, ow_size);
5052 skb_trim(skb,skb->len-win_size);
5053 sk->sent_seq += win_size;
5054 th->seq = htonl(sk->sent_seq);
5055 if (th->urg)
5056 {5057 unsignedshorturg_ptr;
5058
5059 urg_ptr = ntohs(th->urg_ptr);
5060 if (urg_ptr <= win_size)
5061 th->urg = 0;
5062 else5063 {5064 urg_ptr -= win_size;
5065 th->urg_ptr = htons(urg_ptr);
5066 nth->urg_ptr = htons(win_size);
5067 }5068 }5069 #else5070 if(th->urg && ntohs(th->urg_ptr) < win_size)
5071 nth->urg = 0;
5072 #endif5073
5074 /*5075 * Checksum the split buffer5076 */5077
5078 tcp_send_check(nth, sk->saddr, sk->daddr,
5079 nth->doff * 4 + win_size , sk);
5080 }5081 else5082 {5083 buff = sk->prot->wmalloc(sk,MAX_ACK_SIZE,1, GFP_ATOMIC);
5084 if (buff == NULL)
5085 return;
5086
5087 buff->free = 1;
5088 buff->sk = sk;
5089 buff->localroute = sk->localroute;
5090
5091 /*5092 * Put in the IP header and routing stuff. 5093 */5094
5095 tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
5096 IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl);
5097 if (tmp < 0)
5098 {5099 sk->prot->wfree(sk, buff);
5100 return;
5101 }5102
5103 t1 = (structtcphdr *)skb_put(buff,sizeof(structtcphdr));
5104 memcpy(t1,(void *) &sk->dummy_th, sizeof(*t1));
5105
5106 /*5107 * Use a previous sequence.5108 * This should cause the other end to send an ack.5109 */5110
5111 t1->seq = htonl(sk->sent_seq-1);
5112 t1->ack = 1;
5113 t1->res1= 0;
5114 t1->res2= 0;
5115 t1->rst = 0;
5116 t1->urg = 0;
5117 t1->psh = 0;
5118 t1->fin = 0; /* We are sending a 'previous' sequence, and 0 bytes of data - thus no FIN bit */5119 t1->syn = 0;
5120 t1->ack_seq = ntohl(sk->acked_seq);
5121 t1->window = ntohs(tcp_select_window(sk));
5122 t1->doff = sizeof(*t1)/4;
5123 tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), sk);
5124
5125 }5126
5127 /*5128 * Send it.5129 */5130
5131 sk->prot->queue_xmit(sk, dev, buff, 1);
5132 tcp_statistics.TcpOutSegs++;
5133 }5134
5135 /*5136 * A window probe timeout has occurred.5137 */5138
5139 voidtcp_send_probe0(structsock *sk)
/* */5140 {5141 if (sk->zapped)
5142 return; /* After a valid reset we can send no more */5143
5144 tcp_write_wakeup(sk);
5145
5146 sk->backoff++;
5147 sk->rto = min(sk->rto << 1, 120*HZ);
5148 reset_xmit_timer (sk, TIME_PROBE0, sk->rto);
5149 sk->retransmits++;
5150 sk->prot->retransmits ++;
5151 }5152
5153 /*5154 * Socket option code for TCP. 5155 */5156
5157 inttcp_setsockopt(structsock *sk, intlevel, intoptname, char *optval, intoptlen)
/* */5158 {5159 intval,err;
5160
5161 if(level!=SOL_TCP)
5162 returnip_setsockopt(sk,level,optname,optval,optlen);
5163
5164 if (optval == NULL)
5165 return(-EINVAL);
5166
5167 err=verify_area(VERIFY_READ, optval, sizeof(int));
5168 if(err)
5169 returnerr;
5170
5171 val = get_user((int *)optval);
5172
5173 switch(optname)
5174 {5175 caseTCP_MAXSEG:
5176 /*5177 * values greater than interface MTU won't take effect. however at5178 * the point when this call is done we typically don't yet know5179 * which interface is going to be used5180 */5181 if(val<1||val>MAX_WINDOW)
5182 return -EINVAL;
5183 sk->user_mss=val;
5184 return 0;
5185 caseTCP_NODELAY:
5186 sk->nonagle=(val==0)?0:1;
5187 return 0;
5188 default:
5189 return(-ENOPROTOOPT);
5190 }5191 }5192
5193 inttcp_getsockopt(structsock *sk, intlevel, intoptname, char *optval, int *optlen)
/* */5194 {5195 intval,err;
5196
5197 if(level!=SOL_TCP)
5198 returnip_getsockopt(sk,level,optname,optval,optlen);
5199
5200 switch(optname)
5201 {5202 caseTCP_MAXSEG:
5203 val=sk->user_mss;
5204 break;
5205 caseTCP_NODELAY:
5206 val=sk->nonagle;
5207 break;
5208 default:
5209 return(-ENOPROTOOPT);
5210 }5211 err=verify_area(VERIFY_WRITE, optlen, sizeof(int));
5212 if(err)
5213 returnerr;
5214 put_user(sizeof(int),(int *) optlen);
5215
5216 err=verify_area(VERIFY_WRITE, optval, sizeof(int));
5217 if(err)
5218 returnerr;
5219 put_user(val,(int *)optval);
5220
5221 return(0);
5222 }5223
5224
5225 structprototcp_prot = {5226 sock_wmalloc,
5227 sock_rmalloc,
5228 sock_wfree,
5229 sock_rfree,
5230 sock_rspace,
5231 sock_wspace,
5232 tcp_close,
5233 tcp_read,
5234 tcp_write,
5235 tcp_sendto,
5236 tcp_recvfrom,
5237 ip_build_header,
5238 tcp_connect,
5239 tcp_accept,
5240 ip_queue_xmit,
5241 tcp_retransmit,
5242 tcp_write_wakeup,
5243 tcp_read_wakeup,
5244 tcp_rcv,
5245 tcp_select,
5246 tcp_ioctl,
5247 NULL,
5248 tcp_shutdown,
5249 tcp_setsockopt,
5250 tcp_getsockopt,
5251 128,
5252 0,
5253 "TCP",
5254 0, 0,
5255 {NULL,}5256 };