1 /**
2 * @file
3 * Transmission Control Protocol for IP
4 *
5 * This file contains common functions for the TCP implementation, such as functinos
6 * for manipulating the data structures and the TCP timer functions. TCP functions
7 * related to input and output is found in tcp_in.c and tcp_out.c respectively.
8 *
9 */
10
11 /*
12 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
13 * All rights reserved.
14 *
15 * Redistribution and use in source and binary forms, with or without modification,
16 * are permitted provided that the following conditions are met:
17 *
18 * 1. Redistributions of source code must retain the above copyright notice,
19 * this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright notice,
21 * this list of conditions and the following disclaimer in the documentation
22 * and/or other materials provided with the distribution.
23 * 3. The name of the author may not be used to endorse or promote products
24 * derived from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
27 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
28 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
29 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
30 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
31 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
34 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
35 * OF SUCH DAMAGE.
36 *
37 * This file is part of the lwIP TCP/IP stack.
38 *
39 * Author: Adam Dunkels <adam@sics.se>
40 *
41 */
42
43 #include "lwip/opt.h"
44
45 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
46
47 #include "lwip/def.h"
48 #include "lwip/mem.h"
49 #include "lwip/memp.h"
50 #include "lwip/snmp.h"
51 #include "lwip/tcp.h"
52 #include "lwip/tcp_impl.h"
53 #include "lwip/debug.h"
54 #include "lwip/stats.h"
55
56 #include <string.h>
57
58 const char * const tcp_state_str[] = {
59 "CLOSED",
60 "LISTEN",
61 "SYN_SENT",
62 "SYN_RCVD",
63 "ESTABLISHED",
64 "FIN_WAIT_1",
65 "FIN_WAIT_2",
66 "CLOSE_WAIT",
67 "CLOSING",
68 "LAST_ACK",
69 "TIME_WAIT"
70 };
71
72 /* Incremented every coarse grained timer shot (typically every 500 ms). */
73 u32_t tcp_ticks;
74 const u8_t tcp_backoff[13] =
75 { 1, 2, 3, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7};
76 /* Times per slowtmr hits */
77 const u8_t tcp_persist_backoff[7] = { 3, 6, 12, 24, 48, 96, 120 };
78
79 /* The TCP PCB lists. */
80
81 /** List of all TCP PCBs bound but not yet (connected || listening) */
82 struct tcp_pcb *tcp_bound_pcbs;
83 /** List of all TCP PCBs in LISTEN state */
84 union tcp_listen_pcbs_t tcp_listen_pcbs;
85 /** List of all TCP PCBs that are in a state in which
86 * they accept or send data. */
87 struct tcp_pcb *tcp_active_pcbs;
88 /** List of all TCP PCBs in TIME-WAIT state */
89 struct tcp_pcb *tcp_tw_pcbs;
90
91 #define NUM_TCP_PCB_LISTS 4
92 #define NUM_TCP_PCB_LISTS_NO_TIME_WAIT 3
93 /** An array with all (non-temporary) PCB lists, mainly used for smaller code size */
94 struct tcp_pcb ** const tcp_pcb_lists[] = {&tcp_listen_pcbs.pcbs, &tcp_bound_pcbs,
95 &tcp_active_pcbs, &tcp_tw_pcbs};
96
97 /** Only used for temporary storage. */
98 struct tcp_pcb *tcp_tmp_pcb;
99
100 /** Timer counter to handle calling slow-timer from tcp_tmr() */
101 static u8_t tcp_timer;
102 static u16_t tcp_new_port(void);
103
104 /**
105 * Called periodically to dispatch TCP timers.
106 *
107 */
108 void
tcp_tmr(void)109 tcp_tmr(void)
110 {
111 /* Call tcp_fasttmr() every 250 ms */
112 tcp_fasttmr();
113
114 if (++tcp_timer & 1) {
115 /* Call tcp_tmr() every 500 ms, i.e., every other timer
116 tcp_tmr() is called. */
117 tcp_slowtmr();
118 }
119 }
120
121 /**
122 * Closes the TX side of a connection held by the PCB.
123 * For tcp_close(), a RST is sent if the application didn't receive all data
124 * (tcp_recved() not called for all data passed to recv callback).
125 *
126 * Listening pcbs are freed and may not be referenced any more.
127 * Connection pcbs are freed if not yet connected and may not be referenced
128 * any more. If a connection is established (at least SYN received or in
129 * a closing state), the connection is closed, and put in a closing state.
130 * The pcb is then automatically freed in tcp_slowtmr(). It is therefore
131 * unsafe to reference it.
132 *
133 * @param pcb the tcp_pcb to close
134 * @return ERR_OK if connection has been closed
135 * another err_t if closing failed and pcb is not freed
136 */
137 static err_t
tcp_close_shutdown(struct tcp_pcb * pcb,u8_t rst_on_unacked_data)138 tcp_close_shutdown(struct tcp_pcb *pcb, u8_t rst_on_unacked_data)
139 {
140 err_t err;
141
142 if (rst_on_unacked_data && (pcb->state != LISTEN)) {
143 if ((pcb->refused_data != NULL) || (pcb->rcv_wnd != TCP_WND)) {
144 /* Not all data received by application, send RST to tell the remote
145 side about this. */
146 LWIP_ASSERT("pcb->flags & TF_RXCLOSED", pcb->flags & TF_RXCLOSED);
147
148 /* don't call tcp_abort here: we must not deallocate the pcb since
149 that might not be expected when calling tcp_close */
150 tcp_rst(pcb->snd_nxt, pcb->rcv_nxt, &pcb->local_ip, &pcb->remote_ip,
151 pcb->local_port, pcb->remote_port);
152
153 tcp_pcb_purge(pcb);
154
155 /* TODO: to which state do we move now? */
156
157 /* move to TIME_WAIT since we close actively */
158 TCP_RMV(&tcp_active_pcbs, pcb);
159 pcb->state = TIME_WAIT;
160 TCP_REG(&tcp_tw_pcbs, pcb);
161
162 return ERR_OK;
163 }
164 }
165
166 switch (pcb->state) {
167 case CLOSED:
168 /* Closing a pcb in the CLOSED state might seem erroneous,
169 * however, it is in this state once allocated and as yet unused
170 * and the user needs some way to free it should the need arise.
171 * Calling tcp_close() with a pcb that has already been closed, (i.e. twice)
172 * or for a pcb that has been used and then entered the CLOSED state
173 * is erroneous, but this should never happen as the pcb has in those cases
174 * been freed, and so any remaining handles are bogus. */
175 err = ERR_OK;
176 if (pcb->local_port != 0) {
177 TCP_RMV(&tcp_bound_pcbs, pcb);
178 }
179 memp_free(MEMP_TCP_PCB, pcb);
180 pcb = NULL;
181 break;
182 case LISTEN:
183 err = ERR_OK;
184 tcp_pcb_remove(&tcp_listen_pcbs.pcbs, pcb);
185 memp_free(MEMP_TCP_PCB_LISTEN, pcb);
186 pcb = NULL;
187 break;
188 case SYN_SENT:
189 err = ERR_OK;
190 tcp_pcb_remove(&tcp_active_pcbs, pcb);
191 memp_free(MEMP_TCP_PCB, pcb);
192 pcb = NULL;
193 snmp_inc_tcpattemptfails();
194 break;
195 case SYN_RCVD:
196 err = tcp_send_fin(pcb);
197 if (err == ERR_OK) {
198 snmp_inc_tcpattemptfails();
199 pcb->state = FIN_WAIT_1;
200 }
201 break;
202 case ESTABLISHED:
203 err = tcp_send_fin(pcb);
204 if (err == ERR_OK) {
205 snmp_inc_tcpestabresets();
206 pcb->state = FIN_WAIT_1;
207 }
208 break;
209 case CLOSE_WAIT:
210 err = tcp_send_fin(pcb);
211 if (err == ERR_OK) {
212 snmp_inc_tcpestabresets();
213 pcb->state = LAST_ACK;
214 }
215 break;
216 default:
217 /* Has already been closed, do nothing. */
218 err = ERR_OK;
219 pcb = NULL;
220 break;
221 }
222
223 if (pcb != NULL && err == ERR_OK) {
224 /* To ensure all data has been sent when tcp_close returns, we have
225 to make sure tcp_output doesn't fail.
226 Since we don't really have to ensure all data has been sent when tcp_close
227 returns (unsent data is sent from tcp timer functions, also), we don't care
228 for the return value of tcp_output for now. */
229 /* @todo: When implementing SO_LINGER, this must be changed somehow:
230 If SOF_LINGER is set, the data should be sent and acked before close returns.
231 This can only be valid for sequential APIs, not for the raw API. */
232 tcp_output(pcb);
233 }
234 return err;
235 }
236
237 /**
238 * Closes the connection held by the PCB.
239 *
240 * Listening pcbs are freed and may not be referenced any more.
241 * Connection pcbs are freed if not yet connected and may not be referenced
242 * any more. If a connection is established (at least SYN received or in
243 * a closing state), the connection is closed, and put in a closing state.
244 * The pcb is then automatically freed in tcp_slowtmr(). It is therefore
245 * unsafe to reference it (unless an error is returned).
246 *
247 * @param pcb the tcp_pcb to close
248 * @return ERR_OK if connection has been closed
249 * another err_t if closing failed and pcb is not freed
250 */
251 err_t
tcp_close(struct tcp_pcb * pcb)252 tcp_close(struct tcp_pcb *pcb)
253 {
254 #if TCP_DEBUG
255 LWIP_DEBUGF(TCP_DEBUG, ("tcp_close: closing in "));
256 tcp_debug_print_state(pcb->state);
257 #endif /* TCP_DEBUG */
258
259 if (pcb->state != LISTEN) {
260 /* Set a flag not to receive any more data... */
261 pcb->flags |= TF_RXCLOSED;
262 }
263 /* ... and close */
264 return tcp_close_shutdown(pcb, 1);
265 }
266
267 /**
268 * Causes all or part of a full-duplex connection of this PCB to be shut down.
269 * This doesn't deallocate the PCB!
270 *
271 * @param pcb PCB to shutdown
272 * @param shut_rx shut down receive side if this is != 0
273 * @param shut_tx shut down send side if this is != 0
274 * @return ERR_OK if shutdown succeeded (or the PCB has already been shut down)
275 * another err_t on error.
276 */
277 err_t
tcp_shutdown(struct tcp_pcb * pcb,int shut_rx,int shut_tx)278 tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx)
279 {
280 if (pcb->state == LISTEN) {
281 return ERR_CONN;
282 }
283 if (shut_rx) {
284 /* shut down the receive side: free buffered data... */
285 if (pcb->refused_data != NULL) {
286 pbuf_free(pcb->refused_data);
287 pcb->refused_data = NULL;
288 }
289 /* ... and set a flag not to receive any more data */
290 pcb->flags |= TF_RXCLOSED;
291 }
292 if (shut_tx) {
293 /* This can't happen twice since if it succeeds, the pcb's state is changed.
294 Only close in these states as the others directly deallocate the PCB */
295 switch (pcb->state) {
296 case SYN_RCVD:
297 case ESTABLISHED:
298 case CLOSE_WAIT:
299 return tcp_close_shutdown(pcb, 0);
300 default:
301 /* don't shut down other states */
302 break;
303 }
304 }
305 /* @todo: return another err_t if not in correct state or already shut? */
306 return ERR_OK;
307 }
308
309 /**
310 * Abandons a connection and optionally sends a RST to the remote
311 * host. Deletes the local protocol control block. This is done when
312 * a connection is killed because of shortage of memory.
313 *
314 * @param pcb the tcp_pcb to abort
315 * @param reset boolean to indicate whether a reset should be sent
316 */
317 void
tcp_abandon(struct tcp_pcb * pcb,int reset)318 tcp_abandon(struct tcp_pcb *pcb, int reset)
319 {
320 u32_t seqno, ackno;
321 u16_t remote_port, local_port;
322 ip_addr_t remote_ip, local_ip;
323 #if LWIP_CALLBACK_API
324 tcp_err_fn errf;
325 #endif /* LWIP_CALLBACK_API */
326 void *errf_arg;
327
328 /* pcb->state LISTEN not allowed here */
329 LWIP_ASSERT("don't call tcp_abort/tcp_abandon for listen-pcbs",
330 pcb->state != LISTEN);
331 /* Figure out on which TCP PCB list we are, and remove us. If we
332 are in an active state, call the receive function associated with
333 the PCB with a NULL argument, and send an RST to the remote end. */
334 if (pcb->state == TIME_WAIT) {
335 tcp_pcb_remove(&tcp_tw_pcbs, pcb);
336 memp_free(MEMP_TCP_PCB, pcb);
337 } else {
338 seqno = pcb->snd_nxt;
339 ackno = pcb->rcv_nxt;
340 ip_addr_copy(local_ip, pcb->local_ip);
341 ip_addr_copy(remote_ip, pcb->remote_ip);
342 local_port = pcb->local_port;
343 remote_port = pcb->remote_port;
344 #if LWIP_CALLBACK_API
345 errf = pcb->errf;
346 #endif /* LWIP_CALLBACK_API */
347 errf_arg = pcb->callback_arg;
348 tcp_pcb_remove(&tcp_active_pcbs, pcb);
349 if (pcb->unacked != NULL) {
350 tcp_segs_free(pcb->unacked);
351 }
352 if (pcb->unsent != NULL) {
353 tcp_segs_free(pcb->unsent);
354 }
355 #if TCP_QUEUE_OOSEQ
356 if (pcb->ooseq != NULL) {
357 tcp_segs_free(pcb->ooseq);
358 }
359 #endif /* TCP_QUEUE_OOSEQ */
360 memp_free(MEMP_TCP_PCB, pcb);
361 TCP_EVENT_ERR(errf, errf_arg, ERR_ABRT);
362 if (reset) {
363 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_abandon: sending RST\n"));
364 tcp_rst(seqno, ackno, &local_ip, &remote_ip, local_port, remote_port);
365 }
366 }
367 }
368
369 /**
370 * Aborts the connection by sending a RST (reset) segment to the remote
371 * host. The pcb is deallocated. This function never fails.
372 *
373 * ATTENTION: When calling this from one of the TCP callbacks, make
374 * sure you always return ERR_ABRT (and never return ERR_ABRT otherwise
375 * or you will risk accessing deallocated memory or memory leaks!
376 *
377 * @param pcb the tcp pcb to abort
378 */
379 void
tcp_abort(struct tcp_pcb * pcb)380 tcp_abort(struct tcp_pcb *pcb)
381 {
382 tcp_abandon(pcb, 1);
383 }
384
385 /**
386 * Binds the connection to a local portnumber and IP address. If the
387 * IP address is not given (i.e., ipaddr == NULL), the IP address of
388 * the outgoing network interface is used instead.
389 *
390 * @param pcb the tcp_pcb to bind (no check is done whether this pcb is
391 * already bound!)
392 * @param ipaddr the local ip address to bind to (use IP_ADDR_ANY to bind
393 * to any local address
394 * @param port the local port to bind to
395 * @return ERR_USE if the port is already in use
396 * ERR_VAL if bind failed because the PCB is not in a valid state
397 * ERR_OK if bound
398 */
399 err_t
tcp_bind(struct tcp_pcb * pcb,ip_addr_t * ipaddr,u16_t port)400 tcp_bind(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
401 {
402 int i;
403 int max_pcb_list = NUM_TCP_PCB_LISTS;
404 struct tcp_pcb *cpcb;
405
406 LWIP_ERROR("tcp_bind: can only bind in state CLOSED", pcb->state == CLOSED, return ERR_VAL);
407
408 #if SO_REUSE
409 /* Unless the REUSEADDR flag is set,
410 we have to check the pcbs in TIME-WAIT state, also.
411 We do not dump TIME_WAIT pcb's; they can still be matched by incoming
412 packets using both local and remote IP addresses and ports to distinguish.
413 */
414 if ((pcb->so_options & SOF_REUSEADDR) != 0) {
415 max_pcb_list = NUM_TCP_PCB_LISTS_NO_TIME_WAIT;
416 }
417 #endif /* SO_REUSE */
418
419 if (port == 0) {
420 port = tcp_new_port();
421 }
422
423 /* Check if the address already is in use (on all lists) */
424 for (i = 0; i < max_pcb_list; i++) {
425 for(cpcb = *tcp_pcb_lists[i]; cpcb != NULL; cpcb = cpcb->next) {
426 if (cpcb->local_port == port) {
427 #if SO_REUSE
428 /* Omit checking for the same port if both pcbs have REUSEADDR set.
429 For SO_REUSEADDR, the duplicate-check for a 5-tuple is done in
430 tcp_connect. */
431 if (((pcb->so_options & SOF_REUSEADDR) == 0) ||
432 ((cpcb->so_options & SOF_REUSEADDR) == 0))
433 #endif /* SO_REUSE */
434 {
435 if (ip_addr_isany(&(cpcb->local_ip)) ||
436 ip_addr_isany(ipaddr) ||
437 ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
438 return ERR_USE;
439 }
440 }
441 }
442 }
443 }
444
445 if (!ip_addr_isany(ipaddr)) {
446 pcb->local_ip = *ipaddr;
447 }
448 pcb->local_port = port;
449 TCP_REG(&tcp_bound_pcbs, pcb);
450 LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: bind to port %"U16_F"\n", port));
451 return ERR_OK;
452 }
453 #if LWIP_CALLBACK_API
454 /**
455 * Default accept callback if no accept callback is specified by the user.
456 */
457 static err_t
tcp_accept_null(void * arg,struct tcp_pcb * pcb,err_t err)458 tcp_accept_null(void *arg, struct tcp_pcb *pcb, err_t err)
459 {
460 LWIP_UNUSED_ARG(arg);
461 LWIP_UNUSED_ARG(pcb);
462 LWIP_UNUSED_ARG(err);
463
464 return ERR_ABRT;
465 }
466 #endif /* LWIP_CALLBACK_API */
467
468 /**
469 * Set the state of the connection to be LISTEN, which means that it
470 * is able to accept incoming connections. The protocol control block
471 * is reallocated in order to consume less memory. Setting the
472 * connection to LISTEN is an irreversible process.
473 *
474 * @param pcb the original tcp_pcb
475 * @param backlog the incoming connections queue limit
476 * @return tcp_pcb used for listening, consumes less memory.
477 *
478 * @note The original tcp_pcb is freed. This function therefore has to be
479 * called like this:
480 * tpcb = tcp_listen(tpcb);
481 */
482 struct tcp_pcb *
tcp_listen_with_backlog(struct tcp_pcb * pcb,u8_t backlog)483 tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog)
484 {
485 struct tcp_pcb_listen *lpcb;
486
487 LWIP_UNUSED_ARG(backlog);
488 LWIP_ERROR("tcp_listen: pcb already connected", pcb->state == CLOSED, return NULL);
489
490 /* already listening? */
491 if (pcb->state == LISTEN) {
492 return pcb;
493 }
494 #if SO_REUSE
495 if ((pcb->so_options & SOF_REUSEADDR) != 0) {
496 /* Since SOF_REUSEADDR allows reusing a local address before the pcb's usage
497 is declared (listen-/connection-pcb), we have to make sure now that
498 this port is only used once for every local IP. */
499 for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
500 if (lpcb->local_port == pcb->local_port) {
501 if (ip_addr_cmp(&lpcb->local_ip, &pcb->local_ip)) {
502 /* this address/port is already used */
503 return NULL;
504 }
505 }
506 }
507 }
508 #endif /* SO_REUSE */
509 lpcb = (struct tcp_pcb_listen *)memp_malloc(MEMP_TCP_PCB_LISTEN);
510 if (lpcb == NULL) {
511 return NULL;
512 }
513 lpcb->callback_arg = pcb->callback_arg;
514 lpcb->local_port = pcb->local_port;
515 lpcb->state = LISTEN;
516 lpcb->prio = pcb->prio;
517 lpcb->so_options = pcb->so_options;
518 lpcb->so_options |= SOF_ACCEPTCONN;
519 lpcb->ttl = pcb->ttl;
520 lpcb->tos = pcb->tos;
521 ip_addr_copy(lpcb->local_ip, pcb->local_ip);
522 if (pcb->local_port != 0) {
523 TCP_RMV(&tcp_bound_pcbs, pcb);
524 }
525 memp_free(MEMP_TCP_PCB, pcb);
526 #if LWIP_CALLBACK_API
527 lpcb->accept = tcp_accept_null;
528 #endif /* LWIP_CALLBACK_API */
529 #if TCP_LISTEN_BACKLOG
530 lpcb->accepts_pending = 0;
531 lpcb->backlog = (backlog ? backlog : 1);
532 #endif /* TCP_LISTEN_BACKLOG */
533 TCP_REG(&tcp_listen_pcbs.pcbs, (struct tcp_pcb *)lpcb);
534 return (struct tcp_pcb *)lpcb;
535 }
536
537 /**
538 * Update the state that tracks the available window space to advertise.
539 *
540 * Returns how much extra window would be advertised if we sent an
541 * update now.
542 */
tcp_update_rcv_ann_wnd(struct tcp_pcb * pcb)543 u32_t tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb)
544 {
545 u32_t new_right_edge = pcb->rcv_nxt + pcb->rcv_wnd;
546
547 if (TCP_SEQ_GEQ(new_right_edge, pcb->rcv_ann_right_edge + LWIP_MIN((TCP_WND / 2), pcb->mss))) {
548 /* we can advertise more window */
549 pcb->rcv_ann_wnd = pcb->rcv_wnd;
550 return new_right_edge - pcb->rcv_ann_right_edge;
551 } else {
552 if (TCP_SEQ_GT(pcb->rcv_nxt, pcb->rcv_ann_right_edge)) {
553 /* Can happen due to other end sending out of advertised window,
554 * but within actual available (but not yet advertised) window */
555 pcb->rcv_ann_wnd = 0;
556 } else {
557 /* keep the right edge of window constant */
558 u32_t new_rcv_ann_wnd = pcb->rcv_ann_right_edge - pcb->rcv_nxt;
559 LWIP_ASSERT("new_rcv_ann_wnd <= 0xffff", new_rcv_ann_wnd <= 0xffff);
560 pcb->rcv_ann_wnd = (u16_t)new_rcv_ann_wnd;
561 }
562 return 0;
563 }
564 }
565
566 /**
567 * This function should be called by the application when it has
568 * processed the data. The purpose is to advertise a larger window
569 * when the data has been processed.
570 *
571 * @param pcb the tcp_pcb for which data is read
572 * @param len the amount of bytes that have been read by the application
573 */
574 void
tcp_recved(struct tcp_pcb * pcb,u16_t len)575 tcp_recved(struct tcp_pcb *pcb, u16_t len)
576 {
577 int wnd_inflation;
578
579 LWIP_ASSERT("tcp_recved: len would wrap rcv_wnd\n",
580 len <= 0xffff - pcb->rcv_wnd );
581
582 pcb->rcv_wnd += len;
583 if (pcb->rcv_wnd > TCP_WND) {
584 pcb->rcv_wnd = TCP_WND;
585 }
586
587 wnd_inflation = tcp_update_rcv_ann_wnd(pcb);
588
589 /* If the change in the right edge of window is significant (default
590 * watermark is TCP_WND/4), then send an explicit update now.
591 * Otherwise wait for a packet to be sent in the normal course of
592 * events (or more window to be available later) */
593 if (wnd_inflation >= TCP_WND_UPDATE_THRESHOLD) {
594 tcp_ack_now(pcb);
595 tcp_output(pcb);
596 }
597
598 LWIP_DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %"U16_F" bytes, wnd %"U16_F" (%"U16_F").\n",
599 len, pcb->rcv_wnd, TCP_WND - pcb->rcv_wnd));
600 }
601
602 /**
603 * A nastly hack featuring 'goto' statements that allocates a
604 * new TCP local port.
605 *
606 * @return a new (free) local TCP port number
607 */
608 static u16_t
tcp_new_port(void)609 tcp_new_port(void)
610 {
611 int i;
612 struct tcp_pcb *pcb;
613 #ifndef TCP_LOCAL_PORT_RANGE_START
614 /* From http://www.iana.org/assignments/port-numbers:
615 "The Dynamic and/or Private Ports are those from 49152 through 65535" */
616 #define TCP_LOCAL_PORT_RANGE_START 0xc000
617 #define TCP_LOCAL_PORT_RANGE_END 0xffff
618 #endif
619 static u16_t port = TCP_LOCAL_PORT_RANGE_START;
620
621 again:
622 if (port++ >= TCP_LOCAL_PORT_RANGE_END) {
623 port = TCP_LOCAL_PORT_RANGE_START;
624 }
625 /* Check all PCB lists. */
626 for (i = 0; i < NUM_TCP_PCB_LISTS; i++) {
627 for(pcb = *tcp_pcb_lists[i]; pcb != NULL; pcb = pcb->next) {
628 if (pcb->local_port == port) {
629 goto again;
630 }
631 }
632 }
633 return port;
634 }
635
636 /**
637 * Connects to another host. The function given as the "connected"
638 * argument will be called when the connection has been established.
639 *
640 * @param pcb the tcp_pcb used to establish the connection
641 * @param ipaddr the remote ip address to connect to
642 * @param port the remote tcp port to connect to
643 * @param connected callback function to call when connected (or on error)
644 * @return ERR_VAL if invalid arguments are given
645 * ERR_OK if connect request has been sent
646 * other err_t values if connect request couldn't be sent
647 */
648 err_t
tcp_connect(struct tcp_pcb * pcb,ip_addr_t * ipaddr,u16_t port,tcp_connected_fn connected)649 tcp_connect(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port,
650 tcp_connected_fn connected)
651 {
652 err_t ret;
653 u32_t iss;
654 u16_t old_local_port;
655
656 LWIP_ERROR("tcp_connect: can only connect from state CLOSED", pcb->state == CLOSED, return ERR_ISCONN);
657
658 LWIP_DEBUGF(TCP_DEBUG, ("tcp_connect to port %"U16_F"\n", port));
659 if (ipaddr != NULL) {
660 pcb->remote_ip = *ipaddr;
661 } else {
662 return ERR_VAL;
663 }
664 pcb->remote_port = port;
665
666 /* check if we have a route to the remote host */
667 if (ip_addr_isany(&(pcb->local_ip))) {
668 /* no local IP address set, yet. */
669 struct netif *netif = ip_route(&(pcb->remote_ip));
670 if (netif == NULL) {
671 /* Don't even try to send a SYN packet if we have no route
672 since that will fail. */
673 return ERR_RTE;
674 }
675 /* Use the netif's IP address as local address. */
676 ip_addr_copy(pcb->local_ip, netif->ip_addr);
677 }
678
679 old_local_port = pcb->local_port;
680 if (pcb->local_port == 0) {
681 pcb->local_port = tcp_new_port();
682 }
683 #if SO_REUSE
684 if ((pcb->so_options & SOF_REUSEADDR) != 0) {
685 /* Since SOF_REUSEADDR allows reusing a local address, we have to make sure
686 now that the 5-tuple is unique. */
687 struct tcp_pcb *cpcb;
688 int i;
689 /* Don't check listen- and bound-PCBs, check active- and TIME-WAIT PCBs. */
690 for (i = 2; i < NUM_TCP_PCB_LISTS; i++) {
691 for(cpcb = *tcp_pcb_lists[i]; cpcb != NULL; cpcb = cpcb->next) {
692 if ((cpcb->local_port == pcb->local_port) &&
693 (cpcb->remote_port == port) &&
694 ip_addr_cmp(&cpcb->local_ip, &pcb->local_ip) &&
695 ip_addr_cmp(&cpcb->remote_ip, ipaddr)) {
696 /* linux returns EISCONN here, but ERR_USE should be OK for us */
697 return ERR_USE;
698 }
699 }
700 }
701 }
702 #endif /* SO_REUSE */
703 iss = tcp_next_iss();
704 pcb->rcv_nxt = 0;
705 pcb->snd_nxt = iss;
706 pcb->lastack = iss - 1;
707 pcb->snd_lbb = iss - 1;
708 pcb->rcv_wnd = TCP_WND;
709 pcb->rcv_ann_wnd = TCP_WND;
710 pcb->rcv_ann_right_edge = pcb->rcv_nxt;
711 pcb->snd_wnd = TCP_WND;
712 /* As initial send MSS, we use TCP_MSS but limit it to 536.
713 The send MSS is updated when an MSS option is received. */
714 pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS;
715 #if TCP_CALCULATE_EFF_SEND_MSS
716 pcb->mss = tcp_eff_send_mss(pcb->mss, ipaddr);
717 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
718 pcb->cwnd = 1;
719 pcb->ssthresh = pcb->mss * 10;
720 #if LWIP_CALLBACK_API
721 pcb->connected = connected;
722 #else /* LWIP_CALLBACK_API */
723 LWIP_UNUSED_ARG(connected);
724 #endif /* LWIP_CALLBACK_API */
725
726 /* Send a SYN together with the MSS option. */
727 ret = tcp_enqueue_flags(pcb, TCP_SYN);
728 if (ret == ERR_OK) {
729 /* SYN segment was enqueued, changed the pcbs state now */
730 pcb->state = SYN_SENT;
731 if (old_local_port != 0) {
732 TCP_RMV(&tcp_bound_pcbs, pcb);
733 }
734 TCP_REG(&tcp_active_pcbs, pcb);
735 snmp_inc_tcpactiveopens();
736
737 tcp_output(pcb);
738 }
739 return ret;
740 }
741
742 /**
743 * Called every 500 ms and implements the retransmission timer and the timer that
744 * removes PCBs that have been in TIME-WAIT for enough time. It also increments
745 * various timers such as the inactivity timer in each PCB.
746 *
747 * Automatically called from tcp_tmr().
748 */
749 void
tcp_slowtmr(void)750 tcp_slowtmr(void)
751 {
752 struct tcp_pcb *pcb, *prev;
753 u16_t eff_wnd;
754 u8_t pcb_remove; /* flag if a PCB should be removed */
755 u8_t pcb_reset; /* flag if a RST should be sent when removing */
756 err_t err;
757
758 err = ERR_OK;
759
760 ++tcp_ticks;
761
762 /* Steps through all of the active PCBs. */
763 prev = NULL;
764 pcb = tcp_active_pcbs;
765 if (pcb == NULL) {
766 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: no active pcbs\n"));
767 }
768 while (pcb != NULL) {
769 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: processing active pcb\n"));
770 LWIP_ASSERT("tcp_slowtmr: active pcb->state != CLOSED\n", pcb->state != CLOSED);
771 LWIP_ASSERT("tcp_slowtmr: active pcb->state != LISTEN\n", pcb->state != LISTEN);
772 LWIP_ASSERT("tcp_slowtmr: active pcb->state != TIME-WAIT\n", pcb->state != TIME_WAIT);
773
774 pcb_remove = 0;
775 pcb_reset = 0;
776
777 if (pcb->state == SYN_SENT && pcb->nrtx == TCP_SYNMAXRTX) {
778 ++pcb_remove;
779 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max SYN retries reached\n"));
780 }
781 else if (pcb->nrtx == TCP_MAXRTX) {
782 ++pcb_remove;
783 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max DATA retries reached\n"));
784 } else {
785 if (pcb->persist_backoff > 0) {
786 /* If snd_wnd is zero, use persist timer to send 1 byte probes
787 * instead of using the standard retransmission mechanism. */
788 pcb->persist_cnt++;
789 if (pcb->persist_cnt >= tcp_persist_backoff[pcb->persist_backoff-1]) {
790 pcb->persist_cnt = 0;
791 if (pcb->persist_backoff < sizeof(tcp_persist_backoff)) {
792 pcb->persist_backoff++;
793 }
794 tcp_zero_window_probe(pcb);
795 }
796 } else {
797 /* Increase the retransmission timer if it is running */
798 if(pcb->rtime >= 0)
799 ++pcb->rtime;
800
801 if (pcb->unacked != NULL && pcb->rtime >= pcb->rto) {
802 /* Time for a retransmission. */
803 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_slowtmr: rtime %"S16_F
804 " pcb->rto %"S16_F"\n",
805 pcb->rtime, pcb->rto));
806
807 /* Double retransmission time-out unless we are trying to
808 * connect to somebody (i.e., we are in SYN_SENT). */
809 if (pcb->state != SYN_SENT) {
810 pcb->rto = ((pcb->sa >> 3) + pcb->sv) << tcp_backoff[pcb->nrtx];
811 }
812
813 /* Reset the retransmission timer. */
814 pcb->rtime = 0;
815
816 /* Reduce congestion window and ssthresh. */
817 eff_wnd = LWIP_MIN(pcb->cwnd, pcb->snd_wnd);
818 pcb->ssthresh = eff_wnd >> 1;
819 if (pcb->ssthresh < (pcb->mss << 1)) {
820 pcb->ssthresh = (pcb->mss << 1);
821 }
822 pcb->cwnd = pcb->mss;
823 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %"U16_F
824 " ssthresh %"U16_F"\n",
825 pcb->cwnd, pcb->ssthresh));
826
827 /* The following needs to be called AFTER cwnd is set to one
828 mss - STJ */
829 tcp_rexmit_rto(pcb);
830 }
831 }
832 }
833 /* Check if this PCB has stayed too long in FIN-WAIT-2 */
834 if (pcb->state == FIN_WAIT_2) {
835 if ((u32_t)(tcp_ticks - pcb->tmr) >
836 TCP_FIN_WAIT_TIMEOUT / TCP_SLOW_INTERVAL) {
837 ++pcb_remove;
838 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in FIN-WAIT-2\n"));
839 }
840 }
841
842 /* Check if KEEPALIVE should be sent */
843 if((pcb->so_options & SOF_KEEPALIVE) &&
844 ((pcb->state == ESTABLISHED) ||
845 (pcb->state == CLOSE_WAIT))) {
846 #if LWIP_TCP_KEEPALIVE
847 if((u32_t)(tcp_ticks - pcb->tmr) >
848 (pcb->keep_idle + (pcb->keep_cnt*pcb->keep_intvl))
849 / TCP_SLOW_INTERVAL)
850 #else
851 if((u32_t)(tcp_ticks - pcb->tmr) >
852 (pcb->keep_idle + TCP_MAXIDLE) / TCP_SLOW_INTERVAL)
853 #endif /* LWIP_TCP_KEEPALIVE */
854 {
855 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: KEEPALIVE timeout. Aborting connection to %"U16_F".%"U16_F".%"U16_F".%"U16_F".\n",
856 ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
857 ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
858
859 ++pcb_remove;
860 ++pcb_reset;
861 }
862 #if LWIP_TCP_KEEPALIVE
863 else if((u32_t)(tcp_ticks - pcb->tmr) >
864 (pcb->keep_idle + pcb->keep_cnt_sent * pcb->keep_intvl)
865 / TCP_SLOW_INTERVAL)
866 #else
867 else if((u32_t)(tcp_ticks - pcb->tmr) >
868 (pcb->keep_idle + pcb->keep_cnt_sent * TCP_KEEPINTVL_DEFAULT)
869 / TCP_SLOW_INTERVAL)
870 #endif /* LWIP_TCP_KEEPALIVE */
871 {
872 tcp_keepalive(pcb);
873 pcb->keep_cnt_sent++;
874 }
875 }
876
877 /* If this PCB has queued out of sequence data, but has been
878 inactive for too long, will drop the data (it will eventually
879 be retransmitted). */
880 #if TCP_QUEUE_OOSEQ
881 if (pcb->ooseq != NULL &&
882 (u32_t)tcp_ticks - pcb->tmr >= pcb->rto * TCP_OOSEQ_TIMEOUT) {
883 tcp_segs_free(pcb->ooseq);
884 pcb->ooseq = NULL;
885 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: dropping OOSEQ queued data\n"));
886 }
887 #endif /* TCP_QUEUE_OOSEQ */
888
889 /* Check if this PCB has stayed too long in SYN-RCVD */
890 if (pcb->state == SYN_RCVD) {
891 if ((u32_t)(tcp_ticks - pcb->tmr) >
892 TCP_SYN_RCVD_TIMEOUT / TCP_SLOW_INTERVAL) {
893 ++pcb_remove;
894 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in SYN-RCVD\n"));
895 }
896 }
897
898 /* Check if this PCB has stayed too long in LAST-ACK */
899 if (pcb->state == LAST_ACK) {
900 if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) {
901 ++pcb_remove;
902 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in LAST-ACK\n"));
903 }
904 }
905
906 /* If the PCB should be removed, do it. */
907 if (pcb_remove) {
908 struct tcp_pcb *pcb2;
909 tcp_pcb_purge(pcb);
910 /* Remove PCB from tcp_active_pcbs list. */
911 if (prev != NULL) {
912 LWIP_ASSERT("tcp_slowtmr: middle tcp != tcp_active_pcbs", pcb != tcp_active_pcbs);
913 prev->next = pcb->next;
914 } else {
915 /* This PCB was the first. */
916 LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_active_pcbs", tcp_active_pcbs == pcb);
917 tcp_active_pcbs = pcb->next;
918 }
919
920 TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_ABRT);
921 if (pcb_reset) {
922 tcp_rst(pcb->snd_nxt, pcb->rcv_nxt, &pcb->local_ip, &pcb->remote_ip,
923 pcb->local_port, pcb->remote_port);
924 }
925
926 pcb2 = pcb;
927 pcb = pcb->next;
928 memp_free(MEMP_TCP_PCB, pcb2);
929 } else {
930 /* get the 'next' element now and work with 'prev' below (in case of abort) */
931 prev = pcb;
932 pcb = pcb->next;
933
934 /* We check if we should poll the connection. */
935 ++prev->polltmr;
936 if (prev->polltmr >= prev->pollinterval) {
937 prev->polltmr = 0;
938 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: polling application\n"));
939 TCP_EVENT_POLL(prev, err);
940 /* if err == ERR_ABRT, 'prev' is already deallocated */
941 if (err == ERR_OK) {
942 tcp_output(prev);
943 }
944 }
945 }
946 }
947
948
949 /* Steps through all of the TIME-WAIT PCBs. */
950 prev = NULL;
951 pcb = tcp_tw_pcbs;
952 while (pcb != NULL) {
953 LWIP_ASSERT("tcp_slowtmr: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
954 pcb_remove = 0;
955
956 /* Check if this PCB has stayed long enough in TIME-WAIT */
957 if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) {
958 ++pcb_remove;
959 }
960
961
962
963 /* If the PCB should be removed, do it. */
964 if (pcb_remove) {
965 struct tcp_pcb *pcb2;
966 tcp_pcb_purge(pcb);
967 /* Remove PCB from tcp_tw_pcbs list. */
968 if (prev != NULL) {
969 LWIP_ASSERT("tcp_slowtmr: middle tcp != tcp_tw_pcbs", pcb != tcp_tw_pcbs);
970 prev->next = pcb->next;
971 } else {
972 /* This PCB was the first. */
973 LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_tw_pcbs", tcp_tw_pcbs == pcb);
974 tcp_tw_pcbs = pcb->next;
975 }
976 pcb2 = pcb;
977 pcb = pcb->next;
978 memp_free(MEMP_TCP_PCB, pcb2);
979 } else {
980 prev = pcb;
981 pcb = pcb->next;
982 }
983 }
984 }
985
986 /**
987 * Is called every TCP_FAST_INTERVAL (250 ms) and process data previously
988 * "refused" by upper layer (application) and sends delayed ACKs.
989 *
990 * Automatically called from tcp_tmr().
991 */
992 void
tcp_fasttmr(void)993 tcp_fasttmr(void)
994 {
995 struct tcp_pcb *pcb = tcp_active_pcbs;
996
997 while(pcb != NULL) {
998 struct tcp_pcb *next = pcb->next;
999 /* If there is data which was previously "refused" by upper layer */
1000 if (pcb->refused_data != NULL) {
1001 /* Notify again application with data previously received. */
1002 err_t err;
1003 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_fasttmr: notify kept packet\n"));
1004 TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
1005 if (err == ERR_OK) {
1006 pcb->refused_data = NULL;
1007 } else if (err == ERR_ABRT) {
1008 /* if err == ERR_ABRT, 'pcb' is already deallocated */
1009 pcb = NULL;
1010 }
1011 }
1012
1013 /* send delayed ACKs */
1014 if (pcb && (pcb->flags & TF_ACK_DELAY)) {
1015 LWIP_DEBUGF(TCP_DEBUG, ("tcp_fasttmr: delayed ACK\n"));
1016 tcp_ack_now(pcb);
1017 tcp_output(pcb);
1018 pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
1019 }
1020
1021 pcb = next;
1022 }
1023 }
1024
1025 /**
1026 * Deallocates a list of TCP segments (tcp_seg structures).
1027 *
1028 * @param seg tcp_seg list of TCP segments to free
1029 */
1030 void
tcp_segs_free(struct tcp_seg * seg)1031 tcp_segs_free(struct tcp_seg *seg)
1032 {
1033 while (seg != NULL) {
1034 struct tcp_seg *next = seg->next;
1035 tcp_seg_free(seg);
1036 seg = next;
1037 }
1038 }
1039
1040 /**
1041 * Frees a TCP segment (tcp_seg structure).
1042 *
1043 * @param seg single tcp_seg to free
1044 */
1045 void
tcp_seg_free(struct tcp_seg * seg)1046 tcp_seg_free(struct tcp_seg *seg)
1047 {
1048 if (seg != NULL) {
1049 if (seg->p != NULL) {
1050 pbuf_free(seg->p);
1051 #if TCP_DEBUG
1052 seg->p = NULL;
1053 #endif /* TCP_DEBUG */
1054 }
1055 memp_free(MEMP_TCP_SEG, seg);
1056 }
1057 }
1058
1059 /**
1060 * Sets the priority of a connection.
1061 *
1062 * @param pcb the tcp_pcb to manipulate
1063 * @param prio new priority
1064 */
1065 void
tcp_setprio(struct tcp_pcb * pcb,u8_t prio)1066 tcp_setprio(struct tcp_pcb *pcb, u8_t prio)
1067 {
1068 pcb->prio = prio;
1069 }
1070
1071 #if TCP_QUEUE_OOSEQ
1072 /**
1073 * Returns a copy of the given TCP segment.
1074 * The pbuf and data are not copied, only the pointers
1075 *
1076 * @param seg the old tcp_seg
1077 * @return a copy of seg
1078 */
1079 struct tcp_seg *
tcp_seg_copy(struct tcp_seg * seg)1080 tcp_seg_copy(struct tcp_seg *seg)
1081 {
1082 struct tcp_seg *cseg;
1083
1084 cseg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG);
1085 if (cseg == NULL) {
1086 return NULL;
1087 }
1088 SMEMCPY((u8_t *)cseg, (const u8_t *)seg, sizeof(struct tcp_seg));
1089 pbuf_ref(cseg->p);
1090 return cseg;
1091 }
1092 #endif /* TCP_QUEUE_OOSEQ */
1093
1094 #if LWIP_CALLBACK_API
1095 /**
1096 * Default receive callback that is called if the user didn't register
1097 * a recv callback for the pcb.
1098 */
1099 err_t
tcp_recv_null(void * arg,struct tcp_pcb * pcb,struct pbuf * p,err_t err)1100 tcp_recv_null(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
1101 {
1102 LWIP_UNUSED_ARG(arg);
1103 if (p != NULL) {
1104 tcp_recved(pcb, p->tot_len);
1105 pbuf_free(p);
1106 } else if (err == ERR_OK) {
1107 return tcp_close(pcb);
1108 }
1109 return ERR_OK;
1110 }
1111 #endif /* LWIP_CALLBACK_API */
1112
1113 /**
1114 * Kills the oldest active connection that has lower priority than prio.
1115 *
1116 * @param prio minimum priority
1117 */
1118 static void
tcp_kill_prio(u8_t prio)1119 tcp_kill_prio(u8_t prio)
1120 {
1121 struct tcp_pcb *pcb, *inactive;
1122 u32_t inactivity;
1123 u8_t mprio;
1124
1125
1126 mprio = TCP_PRIO_MAX;
1127
1128 /* We kill the oldest active connection that has lower priority than prio. */
1129 inactivity = 0;
1130 inactive = NULL;
1131 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
1132 if (pcb->prio <= prio &&
1133 pcb->prio <= mprio &&
1134 (u32_t)(tcp_ticks - pcb->tmr) >= inactivity) {
1135 inactivity = tcp_ticks - pcb->tmr;
1136 inactive = pcb;
1137 mprio = pcb->prio;
1138 }
1139 }
1140 if (inactive != NULL) {
1141 LWIP_DEBUGF(TCP_DEBUG, ("tcp_kill_prio: killing oldest PCB %p (%"S32_F")\n",
1142 (void *)inactive, inactivity));
1143 tcp_abort(inactive);
1144 }
1145 }
1146
1147 /**
1148 * Kills the oldest connection that is in TIME_WAIT state.
1149 * Called from tcp_alloc() if no more connections are available.
1150 */
1151 static void
tcp_kill_timewait(void)1152 tcp_kill_timewait(void)
1153 {
1154 struct tcp_pcb *pcb, *inactive;
1155 u32_t inactivity;
1156
1157 inactivity = 0;
1158 inactive = NULL;
1159 /* Go through the list of TIME_WAIT pcbs and get the oldest pcb. */
1160 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
1161 if ((u32_t)(tcp_ticks - pcb->tmr) >= inactivity) {
1162 inactivity = tcp_ticks - pcb->tmr;
1163 inactive = pcb;
1164 }
1165 }
1166 if (inactive != NULL) {
1167 LWIP_DEBUGF(TCP_DEBUG, ("tcp_kill_timewait: killing oldest TIME-WAIT PCB %p (%"S32_F")\n",
1168 (void *)inactive, inactivity));
1169 tcp_abort(inactive);
1170 }
1171 }
1172
1173 /**
1174 * Allocate a new tcp_pcb structure.
1175 *
1176 * @param prio priority for the new pcb
1177 * @return a new tcp_pcb that initially is in state CLOSED
1178 */
1179 struct tcp_pcb *
tcp_alloc(u8_t prio)1180 tcp_alloc(u8_t prio)
1181 {
1182 struct tcp_pcb *pcb;
1183 u32_t iss;
1184
1185 pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB);
1186 if (pcb == NULL) {
1187 /* Try killing oldest connection in TIME-WAIT. */
1188 LWIP_DEBUGF(TCP_DEBUG, ("tcp_alloc: killing off oldest TIME-WAIT connection\n"));
1189 tcp_kill_timewait();
1190 /* Try to allocate a tcp_pcb again. */
1191 pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB);
1192 if (pcb == NULL) {
1193 /* Try killing active connections with lower priority than the new one. */
1194 LWIP_DEBUGF(TCP_DEBUG, ("tcp_alloc: killing connection with prio lower than %d\n", prio));
1195 tcp_kill_prio(prio);
1196 /* Try to allocate a tcp_pcb again. */
1197 pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB);
1198 if (pcb != NULL) {
1199 /* adjust err stats: memp_malloc failed twice before */
1200 MEMP_STATS_DEC(err, MEMP_TCP_PCB);
1201 }
1202 }
1203 if (pcb != NULL) {
1204 /* adjust err stats: timewait PCB was freed above */
1205 MEMP_STATS_DEC(err, MEMP_TCP_PCB);
1206 }
1207 }
1208 if (pcb != NULL) {
1209 memset(pcb, 0, sizeof(struct tcp_pcb));
1210 pcb->prio = prio;
1211 pcb->snd_buf = TCP_SND_BUF;
1212 pcb->snd_queuelen = 0;
1213 pcb->rcv_wnd = TCP_WND;
1214 pcb->rcv_ann_wnd = TCP_WND;
1215 pcb->tos = 0;
1216 pcb->ttl = TCP_TTL;
1217 /* As initial send MSS, we use TCP_MSS but limit it to 536.
1218 The send MSS is updated when an MSS option is received. */
1219 pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS;
1220 pcb->rto = 3000 / TCP_SLOW_INTERVAL;
1221 pcb->sa = 0;
1222 pcb->sv = 3000 / TCP_SLOW_INTERVAL;
1223 pcb->rtime = -1;
1224 pcb->cwnd = 1;
1225 iss = tcp_next_iss();
1226 pcb->snd_wl2 = iss;
1227 pcb->snd_nxt = iss;
1228 pcb->lastack = iss;
1229 pcb->snd_lbb = iss;
1230 pcb->tmr = tcp_ticks;
1231
1232 pcb->polltmr = 0;
1233
1234 #if LWIP_CALLBACK_API
1235 pcb->recv = tcp_recv_null;
1236 #endif /* LWIP_CALLBACK_API */
1237
1238 /* Init KEEPALIVE timer */
1239 pcb->keep_idle = TCP_KEEPIDLE_DEFAULT;
1240
1241 #if LWIP_TCP_KEEPALIVE
1242 pcb->keep_intvl = TCP_KEEPINTVL_DEFAULT;
1243 pcb->keep_cnt = TCP_KEEPCNT_DEFAULT;
1244 #endif /* LWIP_TCP_KEEPALIVE */
1245
1246 pcb->keep_cnt_sent = 0;
1247 }
1248 return pcb;
1249 }
1250
1251 /**
1252 * Creates a new TCP protocol control block but doesn't place it on
1253 * any of the TCP PCB lists.
1254 * The pcb is not put on any list until binding using tcp_bind().
1255 *
1256 * @internal: Maybe there should be a idle TCP PCB list where these
1257 * PCBs are put on. Port reservation using tcp_bind() is implemented but
1258 * allocated pcbs that are not bound can't be killed automatically if wanting
1259 * to allocate a pcb with higher prio (@see tcp_kill_prio())
1260 *
1261 * @return a new tcp_pcb that initially is in state CLOSED
1262 */
1263 struct tcp_pcb *
tcp_new(void)1264 tcp_new(void)
1265 {
1266 return tcp_alloc(TCP_PRIO_NORMAL);
1267 }
1268
1269 /**
1270 * Used to specify the argument that should be passed callback
1271 * functions.
1272 *
1273 * @param pcb tcp_pcb to set the callback argument
1274 * @param arg void pointer argument to pass to callback functions
1275 */
1276 void
tcp_arg(struct tcp_pcb * pcb,void * arg)1277 tcp_arg(struct tcp_pcb *pcb, void *arg)
1278 {
1279 pcb->callback_arg = arg;
1280 }
1281 #if LWIP_CALLBACK_API
1282
1283 /**
1284 * Used to specify the function that should be called when a TCP
1285 * connection receives data.
1286 *
1287 * @param pcb tcp_pcb to set the recv callback
1288 * @param recv callback function to call for this pcb when data is received
1289 */
1290 void
tcp_recv(struct tcp_pcb * pcb,tcp_recv_fn recv)1291 tcp_recv(struct tcp_pcb *pcb, tcp_recv_fn recv)
1292 {
1293 pcb->recv = recv;
1294 }
1295
1296 /**
1297 * Used to specify the function that should be called when TCP data
1298 * has been successfully delivered to the remote host.
1299 *
1300 * @param pcb tcp_pcb to set the sent callback
1301 * @param sent callback function to call for this pcb when data is successfully sent
1302 */
1303 void
tcp_sent(struct tcp_pcb * pcb,tcp_sent_fn sent)1304 tcp_sent(struct tcp_pcb *pcb, tcp_sent_fn sent)
1305 {
1306 pcb->sent = sent;
1307 }
1308
1309 /**
1310 * Used to specify the function that should be called when a fatal error
1311 * has occured on the connection.
1312 *
1313 * @param pcb tcp_pcb to set the err callback
1314 * @param err callback function to call for this pcb when a fatal error
1315 * has occured on the connection
1316 */
1317 void
tcp_err(struct tcp_pcb * pcb,tcp_err_fn err)1318 tcp_err(struct tcp_pcb *pcb, tcp_err_fn err)
1319 {
1320 pcb->errf = err;
1321 }
1322
1323 /**
1324 * Used for specifying the function that should be called when a
1325 * LISTENing connection has been connected to another host.
1326 *
1327 * @param pcb tcp_pcb to set the accept callback
1328 * @param accept callback function to call for this pcb when LISTENing
1329 * connection has been connected to another host
1330 */
1331 void
tcp_accept(struct tcp_pcb * pcb,tcp_accept_fn accept)1332 tcp_accept(struct tcp_pcb *pcb, tcp_accept_fn accept)
1333 {
1334 pcb->accept = accept;
1335 }
1336 #endif /* LWIP_CALLBACK_API */
1337
1338
1339 /**
1340 * Used to specify the function that should be called periodically
1341 * from TCP. The interval is specified in terms of the TCP coarse
1342 * timer interval, which is called twice a second.
1343 *
1344 */
1345 void
tcp_poll(struct tcp_pcb * pcb,tcp_poll_fn poll,u8_t interval)1346 tcp_poll(struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval)
1347 {
1348 #if LWIP_CALLBACK_API
1349 pcb->poll = poll;
1350 #else /* LWIP_CALLBACK_API */
1351 LWIP_UNUSED_ARG(poll);
1352 #endif /* LWIP_CALLBACK_API */
1353 pcb->pollinterval = interval;
1354 }
1355
1356 /**
1357 * Purges a TCP PCB. Removes any buffered data and frees the buffer memory
1358 * (pcb->ooseq, pcb->unsent and pcb->unacked are freed).
1359 *
1360 * @param pcb tcp_pcb to purge. The pcb itself is not deallocated!
1361 */
1362 void
tcp_pcb_purge(struct tcp_pcb * pcb)1363 tcp_pcb_purge(struct tcp_pcb *pcb)
1364 {
1365 if (pcb->state != CLOSED &&
1366 pcb->state != TIME_WAIT &&
1367 pcb->state != LISTEN) {
1368
1369 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge\n"));
1370
1371 #if TCP_LISTEN_BACKLOG
1372 if (pcb->state == SYN_RCVD) {
1373 /* Need to find the corresponding listen_pcb and decrease its accepts_pending */
1374 struct tcp_pcb_listen *lpcb;
1375 LWIP_ASSERT("tcp_pcb_purge: pcb->state == SYN_RCVD but tcp_listen_pcbs is NULL",
1376 tcp_listen_pcbs.listen_pcbs != NULL);
1377 for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
1378 if ((lpcb->local_port == pcb->local_port) &&
1379 (ip_addr_isany(&lpcb->local_ip) ||
1380 ip_addr_cmp(&pcb->local_ip, &lpcb->local_ip))) {
1381 /* port and address of the listen pcb match the timed-out pcb */
1382 LWIP_ASSERT("tcp_pcb_purge: listen pcb does not have accepts pending",
1383 lpcb->accepts_pending > 0);
1384 lpcb->accepts_pending--;
1385 break;
1386 }
1387 }
1388 }
1389 #endif /* TCP_LISTEN_BACKLOG */
1390
1391
1392 if (pcb->refused_data != NULL) {
1393 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->refused_data\n"));
1394 pbuf_free(pcb->refused_data);
1395 pcb->refused_data = NULL;
1396 }
1397 if (pcb->unsent != NULL) {
1398 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: not all data sent\n"));
1399 }
1400 if (pcb->unacked != NULL) {
1401 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->unacked\n"));
1402 }
1403 #if TCP_QUEUE_OOSEQ
1404 if (pcb->ooseq != NULL) {
1405 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->ooseq\n"));
1406 }
1407 tcp_segs_free(pcb->ooseq);
1408 pcb->ooseq = NULL;
1409 #endif /* TCP_QUEUE_OOSEQ */
1410
1411 /* Stop the retransmission timer as it will expect data on unacked
1412 queue if it fires */
1413 pcb->rtime = -1;
1414
1415 tcp_segs_free(pcb->unsent);
1416 tcp_segs_free(pcb->unacked);
1417 pcb->unacked = pcb->unsent = NULL;
1418 #if TCP_OVERSIZE
1419 pcb->unsent_oversize = 0;
1420 #endif /* TCP_OVERSIZE */
1421 }
1422 }
1423
1424 /**
1425 * Purges the PCB and removes it from a PCB list. Any delayed ACKs are sent first.
1426 *
1427 * @param pcblist PCB list to purge.
1428 * @param pcb tcp_pcb to purge. The pcb itself is NOT deallocated!
1429 */
1430 void
tcp_pcb_remove(struct tcp_pcb ** pcblist,struct tcp_pcb * pcb)1431 tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb)
1432 {
1433 TCP_RMV(pcblist, pcb);
1434
1435 tcp_pcb_purge(pcb);
1436
1437 /* if there is an outstanding delayed ACKs, send it */
1438 if (pcb->state != TIME_WAIT &&
1439 pcb->state != LISTEN &&
1440 pcb->flags & TF_ACK_DELAY) {
1441 pcb->flags |= TF_ACK_NOW;
1442 tcp_output(pcb);
1443 }
1444
1445 if (pcb->state != LISTEN) {
1446 LWIP_ASSERT("unsent segments leaking", pcb->unsent == NULL);
1447 LWIP_ASSERT("unacked segments leaking", pcb->unacked == NULL);
1448 #if TCP_QUEUE_OOSEQ
1449 LWIP_ASSERT("ooseq segments leaking", pcb->ooseq == NULL);
1450 #endif /* TCP_QUEUE_OOSEQ */
1451 }
1452
1453 pcb->state = CLOSED;
1454
1455 LWIP_ASSERT("tcp_pcb_remove: tcp_pcbs_sane()", tcp_pcbs_sane());
1456 }
1457
1458 /**
1459 * Calculates a new initial sequence number for new connections.
1460 *
1461 * @return u32_t pseudo random sequence number
1462 */
1463 u32_t
tcp_next_iss(void)1464 tcp_next_iss(void)
1465 {
1466 static u32_t iss = 6510;
1467
1468 iss += tcp_ticks; /* XXX */
1469 return iss;
1470 }
1471
1472 #if TCP_CALCULATE_EFF_SEND_MSS
1473 /**
1474 * Calcluates the effective send mss that can be used for a specific IP address
1475 * by using ip_route to determin the netif used to send to the address and
1476 * calculating the minimum of TCP_MSS and that netif's mtu (if set).
1477 */
1478 u16_t
tcp_eff_send_mss(u16_t sendmss,ip_addr_t * addr)1479 tcp_eff_send_mss(u16_t sendmss, ip_addr_t *addr)
1480 {
1481 u16_t mss_s;
1482 struct netif *outif;
1483
1484 outif = ip_route(addr);
1485 if ((outif != NULL) && (outif->mtu != 0)) {
1486 mss_s = outif->mtu - IP_HLEN - TCP_HLEN;
1487 /* RFC 1122, chap 4.2.2.6:
1488 * Eff.snd.MSS = min(SendMSS+20, MMS_S) - TCPhdrsize - IPoptionsize
1489 * We correct for TCP options in tcp_write(), and don't support IP options.
1490 */
1491 sendmss = LWIP_MIN(sendmss, mss_s);
1492 }
1493 return sendmss;
1494 }
1495 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
1496
1497 const char*
tcp_debug_state_str(enum tcp_state s)1498 tcp_debug_state_str(enum tcp_state s)
1499 {
1500 return tcp_state_str[s];
1501 }
1502
1503 #if TCP_DEBUG || TCP_INPUT_DEBUG || TCP_OUTPUT_DEBUG
1504 /**
1505 * Print a tcp header for debugging purposes.
1506 *
1507 * @param tcphdr pointer to a struct tcp_hdr
1508 */
1509 void
tcp_debug_print(struct tcp_hdr * tcphdr)1510 tcp_debug_print(struct tcp_hdr *tcphdr)
1511 {
1512 LWIP_DEBUGF(TCP_DEBUG, ("TCP header:\n"));
1513 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1514 LWIP_DEBUGF(TCP_DEBUG, ("| %5"U16_F" | %5"U16_F" | (src port, dest port)\n",
1515 ntohs(tcphdr->src), ntohs(tcphdr->dest)));
1516 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1517 LWIP_DEBUGF(TCP_DEBUG, ("| %010"U32_F" | (seq no)\n",
1518 ntohl(tcphdr->seqno)));
1519 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1520 LWIP_DEBUGF(TCP_DEBUG, ("| %010"U32_F" | (ack no)\n",
1521 ntohl(tcphdr->ackno)));
1522 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1523 LWIP_DEBUGF(TCP_DEBUG, ("| %2"U16_F" | |%"U16_F"%"U16_F"%"U16_F"%"U16_F"%"U16_F"%"U16_F"| %5"U16_F" | (hdrlen, flags (",
1524 TCPH_HDRLEN(tcphdr),
1525 TCPH_FLAGS(tcphdr) >> 5 & 1,
1526 TCPH_FLAGS(tcphdr) >> 4 & 1,
1527 TCPH_FLAGS(tcphdr) >> 3 & 1,
1528 TCPH_FLAGS(tcphdr) >> 2 & 1,
1529 TCPH_FLAGS(tcphdr) >> 1 & 1,
1530 TCPH_FLAGS(tcphdr) & 1,
1531 ntohs(tcphdr->wnd)));
1532 tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
1533 LWIP_DEBUGF(TCP_DEBUG, ("), win)\n"));
1534 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1535 LWIP_DEBUGF(TCP_DEBUG, ("| 0x%04"X16_F" | %5"U16_F" | (chksum, urgp)\n",
1536 ntohs(tcphdr->chksum), ntohs(tcphdr->urgp)));
1537 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1538 }
1539
1540 /**
1541 * Print a tcp state for debugging purposes.
1542 *
1543 * @param s enum tcp_state to print
1544 */
1545 void
tcp_debug_print_state(enum tcp_state s)1546 tcp_debug_print_state(enum tcp_state s)
1547 {
1548 LWIP_DEBUGF(TCP_DEBUG, ("State: %s\n", tcp_state_str[s]));
1549 }
1550
1551 /**
1552 * Print tcp flags for debugging purposes.
1553 *
1554 * @param flags tcp flags, all active flags are printed
1555 */
1556 void
tcp_debug_print_flags(u8_t flags)1557 tcp_debug_print_flags(u8_t flags)
1558 {
1559 if (flags & TCP_FIN) {
1560 LWIP_DEBUGF(TCP_DEBUG, ("FIN "));
1561 }
1562 if (flags & TCP_SYN) {
1563 LWIP_DEBUGF(TCP_DEBUG, ("SYN "));
1564 }
1565 if (flags & TCP_RST) {
1566 LWIP_DEBUGF(TCP_DEBUG, ("RST "));
1567 }
1568 if (flags & TCP_PSH) {
1569 LWIP_DEBUGF(TCP_DEBUG, ("PSH "));
1570 }
1571 if (flags & TCP_ACK) {
1572 LWIP_DEBUGF(TCP_DEBUG, ("ACK "));
1573 }
1574 if (flags & TCP_URG) {
1575 LWIP_DEBUGF(TCP_DEBUG, ("URG "));
1576 }
1577 if (flags & TCP_ECE) {
1578 LWIP_DEBUGF(TCP_DEBUG, ("ECE "));
1579 }
1580 if (flags & TCP_CWR) {
1581 LWIP_DEBUGF(TCP_DEBUG, ("CWR "));
1582 }
1583 LWIP_DEBUGF(TCP_DEBUG, ("\n"));
1584 }
1585
1586 /**
1587 * Print all tcp_pcbs in every list for debugging purposes.
1588 */
1589 void
tcp_debug_print_pcbs(void)1590 tcp_debug_print_pcbs(void)
1591 {
1592 struct tcp_pcb *pcb;
1593 LWIP_DEBUGF(TCP_DEBUG, ("Active PCB states:\n"));
1594 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
1595 LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
1596 pcb->local_port, pcb->remote_port,
1597 pcb->snd_nxt, pcb->rcv_nxt));
1598 tcp_debug_print_state(pcb->state);
1599 }
1600 LWIP_DEBUGF(TCP_DEBUG, ("Listen PCB states:\n"));
1601 for(pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next) {
1602 LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
1603 pcb->local_port, pcb->remote_port,
1604 pcb->snd_nxt, pcb->rcv_nxt));
1605 tcp_debug_print_state(pcb->state);
1606 }
1607 LWIP_DEBUGF(TCP_DEBUG, ("TIME-WAIT PCB states:\n"));
1608 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
1609 LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
1610 pcb->local_port, pcb->remote_port,
1611 pcb->snd_nxt, pcb->rcv_nxt));
1612 tcp_debug_print_state(pcb->state);
1613 }
1614 }
1615
1616 /**
1617 * Check state consistency of the tcp_pcb lists.
1618 */
1619 s16_t
tcp_pcbs_sane(void)1620 tcp_pcbs_sane(void)
1621 {
1622 struct tcp_pcb *pcb;
1623 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
1624 LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != CLOSED", pcb->state != CLOSED);
1625 LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != LISTEN", pcb->state != LISTEN);
1626 LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
1627 }
1628 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
1629 LWIP_ASSERT("tcp_pcbs_sane: tw pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
1630 }
1631 return 1;
1632 }
1633 #endif /* TCP_DEBUG */
1634
1635 #endif /* LWIP_TCP */
1636