3 * Transmission Control Protocol for IP
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.
12 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
13 * All rights reserved.
15 * Redistribution and use in source and binary forms, with or without modification,
16 * are permitted provided that the following conditions are met:
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.
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
37 * This file is part of the lwIP TCP/IP stack.
39 * Author: Adam Dunkels <adam@sics.se>
45 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
49 #include "lwip/memp.h"
50 #include "lwip/snmp.h"
52 #include "lwip/debug.h"
53 #include "lwip/stats.h"
57 const char *tcp_state_str[] = {
71 /* Incremented every coarse grained timer shot (typically every 500 ms). */
73 const u8_t tcp_backoff[13] =
74 { 1, 2, 3, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7};
75 /* Times per slowtmr hits */
76 const u8_t tcp_persist_backoff[7] = { 3, 6, 12, 24, 48, 96, 120 };
78 /* The TCP PCB lists. */
80 /** List of all TCP PCBs bound but not yet (connected || listening) */
81 struct tcp_pcb *tcp_bound_pcbs;
82 /** List of all TCP PCBs in LISTEN state */
83 union tcp_listen_pcbs_t tcp_listen_pcbs;
84 /** List of all TCP PCBs that are in a state in which
85 * they accept or send data. */
86 struct tcp_pcb *tcp_active_pcbs;
87 /** List of all TCP PCBs in TIME-WAIT state */
88 struct tcp_pcb *tcp_tw_pcbs;
90 /** Only used for temporary storage. */
91 struct tcp_pcb *tcp_tmp_pcb;
93 /** Timer counter to handle calling slow-timer from tcp_tmr() */
94 static u8_t tcp_timer;
95 static u16_t tcp_new_port(void);
98 * Called periodically to dispatch TCP timers.
104 /* Call tcp_fasttmr() every 250 ms */
107 if (++tcp_timer & 1) {
108 /* Call tcp_tmr() every 500 ms, i.e., every other timer
109 tcp_tmr() is called. */
115 * Closes the connection held by the PCB.
117 * Listening pcbs are freed and may not be referenced any more.
118 * Connection pcbs are freed if not yet connected and may not be referenced
119 * any more. If a connection is established (at least SYN received or in
120 * a closing state), the connection is closed, and put in a closing state.
121 * The pcb is then automatically freed in tcp_slowtmr(). It is therefore
122 * unsafe to reference it.
124 * @param pcb the tcp_pcb to close
125 * @return ERR_OK if connection has been closed
126 * another err_t if closing failed and pcb is not freed
129 tcp_close(struct tcp_pcb *pcb)
134 LWIP_DEBUGF(TCP_DEBUG, ("tcp_close: closing in "));
135 tcp_debug_print_state(pcb->state);
136 #endif /* TCP_DEBUG */
138 switch (pcb->state) {
140 /* Closing a pcb in the CLOSED state might seem erroneous,
141 * however, it is in this state once allocated and as yet unused
142 * and the user needs some way to free it should the need arise.
143 * Calling tcp_close() with a pcb that has already been closed, (i.e. twice)
144 * or for a pcb that has been used and then entered the CLOSED state
145 * is erroneous, but this should never happen as the pcb has in those cases
146 * been freed, and so any remaining handles are bogus. */
148 TCP_RMV(&tcp_bound_pcbs, pcb);
149 memp_free(MEMP_TCP_PCB, pcb);
154 tcp_pcb_remove((struct tcp_pcb **)&tcp_listen_pcbs.pcbs, pcb);
155 memp_free(MEMP_TCP_PCB_LISTEN, pcb);
160 tcp_pcb_remove(&tcp_active_pcbs, pcb);
161 memp_free(MEMP_TCP_PCB, pcb);
163 snmp_inc_tcpattemptfails();
166 err = tcp_send_ctrl(pcb, TCP_FIN);
168 snmp_inc_tcpattemptfails();
169 pcb->state = FIN_WAIT_1;
173 err = tcp_send_ctrl(pcb, TCP_FIN);
175 snmp_inc_tcpestabresets();
176 pcb->state = FIN_WAIT_1;
180 err = tcp_send_ctrl(pcb, TCP_FIN);
182 snmp_inc_tcpestabresets();
183 pcb->state = LAST_ACK;
187 /* Has already been closed, do nothing. */
193 if (pcb != NULL && err == ERR_OK) {
194 /* To ensure all data has been sent when tcp_close returns, we have
195 to make sure tcp_output doesn't fail.
196 Since we don't really have to ensure all data has been sent when tcp_close
197 returns (unsent data is sent from tcp timer functions, also), we don't care
198 for the return value of tcp_output for now. */
199 /* @todo: When implementing SO_LINGER, this must be changed somehow:
200 If SOF_LINGER is set, the data should be sent when tcp_close returns. */
207 * Abandons a connection and optionally sends a RST to the remote
208 * host. Deletes the local protocol control block. This is done when
209 * a connection is killed because of shortage of memory.
211 * @param pcb the tcp_pcb to abort
212 * @param reset boolean to indicate whether a reset should be sent
215 tcp_abandon(struct tcp_pcb *pcb, int reset)
218 u16_t remote_port, local_port;
219 struct ip_addr remote_ip, local_ip;
220 #if LWIP_CALLBACK_API
222 #endif /* LWIP_CALLBACK_API */
226 /* Figure out on which TCP PCB list we are, and remove us. If we
227 are in an active state, call the receive function associated with
228 the PCB with a NULL argument, and send an RST to the remote end. */
229 if (pcb->state == TIME_WAIT) {
230 tcp_pcb_remove(&tcp_tw_pcbs, pcb);
231 memp_free(MEMP_TCP_PCB, pcb);
233 seqno = pcb->snd_nxt;
234 ackno = pcb->rcv_nxt;
235 ip_addr_set(&local_ip, &(pcb->local_ip));
236 ip_addr_set(&remote_ip, &(pcb->remote_ip));
237 local_port = pcb->local_port;
238 remote_port = pcb->remote_port;
239 #if LWIP_CALLBACK_API
241 #endif /* LWIP_CALLBACK_API */
242 errf_arg = pcb->callback_arg;
243 tcp_pcb_remove(&tcp_active_pcbs, pcb);
244 if (pcb->unacked != NULL) {
245 tcp_segs_free(pcb->unacked);
247 if (pcb->unsent != NULL) {
248 tcp_segs_free(pcb->unsent);
251 if (pcb->ooseq != NULL) {
252 tcp_segs_free(pcb->ooseq);
254 #endif /* TCP_QUEUE_OOSEQ */
255 memp_free(MEMP_TCP_PCB, pcb);
256 TCP_EVENT_ERR(errf, errf_arg, ERR_ABRT);
258 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_abandon: sending RST\n"));
259 tcp_rst(seqno, ackno, &local_ip, &remote_ip, local_port, remote_port);
265 * Binds the connection to a local portnumber and IP address. If the
266 * IP address is not given (i.e., ipaddr == NULL), the IP address of
267 * the outgoing network interface is used instead.
269 * @param pcb the tcp_pcb to bind (no check is done whether this pcb is
271 * @param ipaddr the local ip address to bind to (use IP_ADDR_ANY to bind
272 * to any local address
273 * @param port the local port to bind to
274 * @return ERR_USE if the port is already in use
278 tcp_bind(struct tcp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
280 struct tcp_pcb *cpcb;
282 LWIP_ERROR("tcp_bind: can only bind in state CLOSED", pcb->state == CLOSED, return ERR_ISCONN);
285 port = tcp_new_port();
287 /* Check if the address already is in use. */
288 /* Check the listen pcbs. */
289 for(cpcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs;
290 cpcb != NULL; cpcb = cpcb->next) {
291 if (cpcb->local_port == port) {
292 if (ip_addr_isany(&(cpcb->local_ip)) ||
293 ip_addr_isany(ipaddr) ||
294 ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
299 /* Check the connected pcbs. */
300 for(cpcb = tcp_active_pcbs;
301 cpcb != NULL; cpcb = cpcb->next) {
302 if (cpcb->local_port == port) {
303 if (ip_addr_isany(&(cpcb->local_ip)) ||
304 ip_addr_isany(ipaddr) ||
305 ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
310 /* Check the bound, not yet connected pcbs. */
311 for(cpcb = tcp_bound_pcbs; cpcb != NULL; cpcb = cpcb->next) {
312 if (cpcb->local_port == port) {
313 if (ip_addr_isany(&(cpcb->local_ip)) ||
314 ip_addr_isany(ipaddr) ||
315 ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
320 /* @todo: until SO_REUSEADDR is implemented (see task #6995 on savannah),
321 * we have to check the pcbs in TIME-WAIT state, also: */
322 for(cpcb = tcp_tw_pcbs; cpcb != NULL; cpcb = cpcb->next) {
323 if (cpcb->local_port == port) {
324 if (ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
330 if (!ip_addr_isany(ipaddr)) {
331 pcb->local_ip = *ipaddr;
333 pcb->local_port = port;
334 TCP_REG(&tcp_bound_pcbs, pcb);
335 LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: bind to port %"U16_F"\n", port));
338 #if LWIP_CALLBACK_API
340 * Default accept callback if no accept callback is specified by the user.
343 tcp_accept_null(void *arg, struct tcp_pcb *pcb, err_t err)
345 LWIP_UNUSED_ARG(arg);
346 LWIP_UNUSED_ARG(pcb);
347 LWIP_UNUSED_ARG(err);
351 #endif /* LWIP_CALLBACK_API */
354 * Set the state of the connection to be LISTEN, which means that it
355 * is able to accept incoming connections. The protocol control block
356 * is reallocated in order to consume less memory. Setting the
357 * connection to LISTEN is an irreversible process.
359 * @param pcb the original tcp_pcb
360 * @param backlog the incoming connections queue limit
361 * @return tcp_pcb used for listening, consumes less memory.
363 * @note The original tcp_pcb is freed. This function therefore has to be
365 * tpcb = tcp_listen(tpcb);
368 tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog)
370 struct tcp_pcb_listen *lpcb;
372 LWIP_UNUSED_ARG(backlog);
373 LWIP_ERROR("tcp_listen: pcb already connected", pcb->state == CLOSED, return NULL);
375 /* already listening? */
376 if (pcb->state == LISTEN) {
379 lpcb = memp_malloc(MEMP_TCP_PCB_LISTEN);
383 lpcb->callback_arg = pcb->callback_arg;
384 lpcb->local_port = pcb->local_port;
385 lpcb->state = LISTEN;
386 lpcb->so_options = pcb->so_options;
387 lpcb->so_options |= SOF_ACCEPTCONN;
388 lpcb->ttl = pcb->ttl;
389 lpcb->tos = pcb->tos;
390 ip_addr_set(&lpcb->local_ip, &pcb->local_ip);
391 TCP_RMV(&tcp_bound_pcbs, pcb);
392 memp_free(MEMP_TCP_PCB, pcb);
393 #if LWIP_CALLBACK_API
394 lpcb->accept = tcp_accept_null;
395 #endif /* LWIP_CALLBACK_API */
396 #if TCP_LISTEN_BACKLOG
397 lpcb->accepts_pending = 0;
398 lpcb->backlog = (backlog ? backlog : 1);
399 #endif /* TCP_LISTEN_BACKLOG */
400 TCP_REG(&tcp_listen_pcbs.listen_pcbs, lpcb);
401 return (struct tcp_pcb *)lpcb;
405 * Update the state that tracks the available window space to advertise.
407 * Returns how much extra window would be advertised if we sent an
410 u32_t tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb)
412 u32_t new_right_edge = pcb->rcv_nxt + pcb->rcv_wnd;
414 if (TCP_SEQ_GEQ(new_right_edge, pcb->rcv_ann_right_edge + LWIP_MIN((TCP_WND / 2), pcb->mss))) {
415 /* we can advertise more window */
416 pcb->rcv_ann_wnd = pcb->rcv_wnd;
417 return new_right_edge - pcb->rcv_ann_right_edge;
419 if (TCP_SEQ_GT(pcb->rcv_nxt, pcb->rcv_ann_right_edge)) {
420 /* Can happen due to other end sending out of advertised window,
421 * but within actual available (but not yet advertised) window */
422 pcb->rcv_ann_wnd = 0;
424 /* keep the right edge of window constant */
425 pcb->rcv_ann_wnd = pcb->rcv_ann_right_edge - pcb->rcv_nxt;
432 * This function should be called by the application when it has
433 * processed the data. The purpose is to advertise a larger window
434 * when the data has been processed.
436 * @param pcb the tcp_pcb for which data is read
437 * @param len the amount of bytes that have been read by the application
440 tcp_recved(struct tcp_pcb *pcb, u16_t len)
444 LWIP_ASSERT("tcp_recved: len would wrap rcv_wnd\n",
445 len <= 0xffff - pcb->rcv_wnd );
448 if (pcb->rcv_wnd > TCP_WND)
449 pcb->rcv_wnd = TCP_WND;
451 wnd_inflation = tcp_update_rcv_ann_wnd(pcb);
453 /* If the change in the right edge of window is significant (default
454 * watermark is TCP_WND/2), then send an explicit update now.
455 * Otherwise wait for a packet to be sent in the normal course of
456 * events (or more window to be available later) */
457 if (wnd_inflation >= TCP_WND_UPDATE_THRESHOLD) {
462 LWIP_DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %"U16_F" bytes, wnd %"U16_F" (%"U16_F").\n",
463 len, pcb->rcv_wnd, TCP_WND - pcb->rcv_wnd));
467 * A nastly hack featuring 'goto' statements that allocates a
468 * new TCP local port.
470 * @return a new (free) local TCP port number
476 #ifndef TCP_LOCAL_PORT_RANGE_START
477 #define TCP_LOCAL_PORT_RANGE_START 4096
478 #define TCP_LOCAL_PORT_RANGE_END 0x7fff
480 static u16_t port = TCP_LOCAL_PORT_RANGE_START;
483 if (++port > TCP_LOCAL_PORT_RANGE_END) {
484 port = TCP_LOCAL_PORT_RANGE_START;
487 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
488 if (pcb->local_port == port) {
492 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
493 if (pcb->local_port == port) {
497 for(pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next) {
498 if (pcb->local_port == port) {
506 * Connects to another host. The function given as the "connected"
507 * argument will be called when the connection has been established.
509 * @param pcb the tcp_pcb used to establish the connection
510 * @param ipaddr the remote ip address to connect to
511 * @param port the remote tcp port to connect to
512 * @param connected callback function to call when connected (or on error)
513 * @return ERR_VAL if invalid arguments are given
514 * ERR_OK if connect request has been sent
515 * other err_t values if connect request couldn't be sent
518 tcp_connect(struct tcp_pcb *pcb, struct ip_addr *ipaddr, u16_t port,
519 tcp_connected_fn connected)
524 LWIP_ERROR("tcp_connect: can only connected from state CLOSED", pcb->state == CLOSED, return ERR_ISCONN);
526 LWIP_DEBUGF(TCP_DEBUG, ("tcp_connect to port %"U16_F"\n", port));
527 if (ipaddr != NULL) {
528 pcb->remote_ip = *ipaddr;
532 pcb->remote_port = port;
533 if (pcb->local_port == 0) {
534 pcb->local_port = tcp_new_port();
536 iss = tcp_next_iss();
539 pcb->lastack = iss - 1;
540 pcb->snd_lbb = iss - 1;
541 pcb->rcv_wnd = TCP_WND;
542 pcb->rcv_ann_wnd = TCP_WND;
543 pcb->rcv_ann_right_edge = pcb->rcv_nxt;
544 pcb->snd_wnd = TCP_WND;
545 /* As initial send MSS, we use TCP_MSS but limit it to 536.
546 The send MSS is updated when an MSS option is received. */
547 pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS;
548 #if TCP_CALCULATE_EFF_SEND_MSS
549 pcb->mss = tcp_eff_send_mss(pcb->mss, ipaddr);
550 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
552 pcb->ssthresh = pcb->mss * 10;
553 #if LWIP_CALLBACK_API
554 pcb->connected = connected;
555 #endif /* LWIP_CALLBACK_API */
557 ret = tcp_enqueue(pcb, NULL, 0, TCP_SYN, 0, TF_SEG_OPTS_MSS
558 #if LWIP_TCP_TIMESTAMPS
563 /* SYN segment was enqueued, changed the pcbs state now */
564 pcb->state = SYN_SENT;
565 TCP_RMV(&tcp_bound_pcbs, pcb);
566 TCP_REG(&tcp_active_pcbs, pcb);
567 snmp_inc_tcpactiveopens();
575 * Called every 500 ms and implements the retransmission timer and the timer that
576 * removes PCBs that have been in TIME-WAIT for enough time. It also increments
577 * various timers such as the inactivity timer in each PCB.
579 * Automatically called from tcp_tmr().
584 struct tcp_pcb *pcb, *pcb2, *prev;
586 u8_t pcb_remove; /* flag if a PCB should be removed */
587 u8_t pcb_reset; /* flag if a RST should be sent when removing */
594 /* Steps through all of the active PCBs. */
596 pcb = tcp_active_pcbs;
598 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: no active pcbs\n"));
600 while (pcb != NULL) {
601 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: processing active pcb\n"));
602 LWIP_ASSERT("tcp_slowtmr: active pcb->state != CLOSED\n", pcb->state != CLOSED);
603 LWIP_ASSERT("tcp_slowtmr: active pcb->state != LISTEN\n", pcb->state != LISTEN);
604 LWIP_ASSERT("tcp_slowtmr: active pcb->state != TIME-WAIT\n", pcb->state != TIME_WAIT);
609 if (pcb->state == SYN_SENT && pcb->nrtx == TCP_SYNMAXRTX) {
611 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max SYN retries reached\n"));
613 else if (pcb->nrtx == TCP_MAXRTX) {
615 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max DATA retries reached\n"));
617 if (pcb->persist_backoff > 0) {
618 /* If snd_wnd is zero, use persist timer to send 1 byte probes
619 * instead of using the standard retransmission mechanism. */
621 if (pcb->persist_cnt >= tcp_persist_backoff[pcb->persist_backoff-1]) {
622 pcb->persist_cnt = 0;
623 if (pcb->persist_backoff < sizeof(tcp_persist_backoff)) {
624 pcb->persist_backoff++;
626 tcp_zero_window_probe(pcb);
629 /* Increase the retransmission timer if it is running */
633 if (pcb->unacked != NULL && pcb->rtime >= pcb->rto) {
634 /* Time for a retransmission. */
635 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_slowtmr: rtime %"S16_F
636 " pcb->rto %"S16_F"\n",
637 pcb->rtime, pcb->rto));
639 /* Double retransmission time-out unless we are trying to
640 * connect to somebody (i.e., we are in SYN_SENT). */
641 if (pcb->state != SYN_SENT) {
642 pcb->rto = ((pcb->sa >> 3) + pcb->sv) << tcp_backoff[pcb->nrtx];
645 /* Reset the retransmission timer. */
648 /* Reduce congestion window and ssthresh. */
649 eff_wnd = LWIP_MIN(pcb->cwnd, pcb->snd_wnd);
650 pcb->ssthresh = eff_wnd >> 1;
651 if (pcb->ssthresh < pcb->mss) {
652 pcb->ssthresh = pcb->mss * 2;
654 pcb->cwnd = pcb->mss;
655 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %"U16_F
656 " ssthresh %"U16_F"\n",
657 pcb->cwnd, pcb->ssthresh));
659 /* The following needs to be called AFTER cwnd is set to one
665 /* Check if this PCB has stayed too long in FIN-WAIT-2 */
666 if (pcb->state == FIN_WAIT_2) {
667 if ((u32_t)(tcp_ticks - pcb->tmr) >
668 TCP_FIN_WAIT_TIMEOUT / TCP_SLOW_INTERVAL) {
670 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in FIN-WAIT-2\n"));
674 /* Check if KEEPALIVE should be sent */
675 if((pcb->so_options & SOF_KEEPALIVE) &&
676 ((pcb->state == ESTABLISHED) ||
677 (pcb->state == CLOSE_WAIT))) {
678 #if LWIP_TCP_KEEPALIVE
679 if((u32_t)(tcp_ticks - pcb->tmr) >
680 (pcb->keep_idle + (pcb->keep_cnt*pcb->keep_intvl))
683 if((u32_t)(tcp_ticks - pcb->tmr) >
684 (pcb->keep_idle + TCP_MAXIDLE) / TCP_SLOW_INTERVAL)
685 #endif /* LWIP_TCP_KEEPALIVE */
687 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: KEEPALIVE timeout. Aborting connection to %"U16_F".%"U16_F".%"U16_F".%"U16_F".\n",
688 ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
689 ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip)));
694 #if LWIP_TCP_KEEPALIVE
695 else if((u32_t)(tcp_ticks - pcb->tmr) >
696 (pcb->keep_idle + pcb->keep_cnt_sent * pcb->keep_intvl)
699 else if((u32_t)(tcp_ticks - pcb->tmr) >
700 (pcb->keep_idle + pcb->keep_cnt_sent * TCP_KEEPINTVL_DEFAULT)
702 #endif /* LWIP_TCP_KEEPALIVE */
705 pcb->keep_cnt_sent++;
709 /* If this PCB has queued out of sequence data, but has been
710 inactive for too long, will drop the data (it will eventually
711 be retransmitted). */
713 if (pcb->ooseq != NULL &&
714 (u32_t)tcp_ticks - pcb->tmr >= pcb->rto * TCP_OOSEQ_TIMEOUT) {
715 tcp_segs_free(pcb->ooseq);
717 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: dropping OOSEQ queued data\n"));
719 #endif /* TCP_QUEUE_OOSEQ */
721 /* Check if this PCB has stayed too long in SYN-RCVD */
722 if (pcb->state == SYN_RCVD) {
723 if ((u32_t)(tcp_ticks - pcb->tmr) >
724 TCP_SYN_RCVD_TIMEOUT / TCP_SLOW_INTERVAL) {
726 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in SYN-RCVD\n"));
730 /* Check if this PCB has stayed too long in LAST-ACK */
731 if (pcb->state == LAST_ACK) {
732 if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) {
734 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in LAST-ACK\n"));
738 /* If the PCB should be removed, do it. */
741 /* Remove PCB from tcp_active_pcbs list. */
743 LWIP_ASSERT("tcp_slowtmr: middle tcp != tcp_active_pcbs", pcb != tcp_active_pcbs);
744 prev->next = pcb->next;
746 /* This PCB was the first. */
747 LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_active_pcbs", tcp_active_pcbs == pcb);
748 tcp_active_pcbs = pcb->next;
751 TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_ABRT);
753 tcp_rst(pcb->snd_nxt, pcb->rcv_nxt, &pcb->local_ip, &pcb->remote_ip,
754 pcb->local_port, pcb->remote_port);
758 memp_free(MEMP_TCP_PCB, pcb);
762 /* We check if we should poll the connection. */
764 if (pcb->polltmr >= pcb->pollinterval) {
766 LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: polling application\n"));
767 TCP_EVENT_POLL(pcb, err);
779 /* Steps through all of the TIME-WAIT PCBs. */
782 while (pcb != NULL) {
783 LWIP_ASSERT("tcp_slowtmr: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
786 /* Check if this PCB has stayed long enough in TIME-WAIT */
787 if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) {
793 /* If the PCB should be removed, do it. */
796 /* Remove PCB from tcp_tw_pcbs list. */
798 LWIP_ASSERT("tcp_slowtmr: middle tcp != tcp_tw_pcbs", pcb != tcp_tw_pcbs);
799 prev->next = pcb->next;
801 /* This PCB was the first. */
802 LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_tw_pcbs", tcp_tw_pcbs == pcb);
803 tcp_tw_pcbs = pcb->next;
806 memp_free(MEMP_TCP_PCB, pcb);
816 * Is called every TCP_FAST_INTERVAL (250 ms) and process data previously
817 * "refused" by upper layer (application) and sends delayed ACKs.
819 * Automatically called from tcp_tmr().
826 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
827 /* If there is data which was previously "refused" by upper layer */
828 if (pcb->refused_data != NULL) {
829 /* Notify again application with data previously received. */
831 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_fasttmr: notify kept packet\n"));
832 TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
834 pcb->refused_data = NULL;
838 /* send delayed ACKs */
839 if (pcb->flags & TF_ACK_DELAY) {
840 LWIP_DEBUGF(TCP_DEBUG, ("tcp_fasttmr: delayed ACK\n"));
843 pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
849 * Deallocates a list of TCP segments (tcp_seg structures).
851 * @param seg tcp_seg list of TCP segments to free
852 * @return the number of pbufs that were deallocated
855 tcp_segs_free(struct tcp_seg *seg)
858 struct tcp_seg *next;
859 while (seg != NULL) {
861 count += tcp_seg_free(seg);
868 * Frees a TCP segment (tcp_seg structure).
870 * @param seg single tcp_seg to free
871 * @return the number of pbufs that were deallocated
874 tcp_seg_free(struct tcp_seg *seg)
879 if (seg->p != NULL) {
880 count = pbuf_free(seg->p);
883 #endif /* TCP_DEBUG */
885 memp_free(MEMP_TCP_SEG, seg);
891 * Sets the priority of a connection.
893 * @param pcb the tcp_pcb to manipulate
894 * @param prio new priority
897 tcp_setprio(struct tcp_pcb *pcb, u8_t prio)
904 * Returns a copy of the given TCP segment.
905 * The pbuf and data are not copied, only the pointers
907 * @param seg the old tcp_seg
908 * @return a copy of seg
911 tcp_seg_copy(struct tcp_seg *seg)
913 struct tcp_seg *cseg;
915 cseg = memp_malloc(MEMP_TCP_SEG);
919 SMEMCPY((u8_t *)cseg, (const u8_t *)seg, sizeof(struct tcp_seg));
925 #if LWIP_CALLBACK_API
927 * Default receive callback that is called if the user didn't register
928 * a recv callback for the pcb.
931 tcp_recv_null(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
933 LWIP_UNUSED_ARG(arg);
935 tcp_recved(pcb, p->tot_len);
937 } else if (err == ERR_OK) {
938 return tcp_close(pcb);
942 #endif /* LWIP_CALLBACK_API */
945 * Kills the oldest active connection that has lower priority than prio.
947 * @param prio minimum priority
950 tcp_kill_prio(u8_t prio)
952 struct tcp_pcb *pcb, *inactive;
957 mprio = TCP_PRIO_MAX;
959 /* We kill the oldest active connection that has lower priority than prio. */
962 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
963 if (pcb->prio <= prio &&
964 pcb->prio <= mprio &&
965 (u32_t)(tcp_ticks - pcb->tmr) >= inactivity) {
966 inactivity = tcp_ticks - pcb->tmr;
971 if (inactive != NULL) {
972 LWIP_DEBUGF(TCP_DEBUG, ("tcp_kill_prio: killing oldest PCB %p (%"S32_F")\n",
973 (void *)inactive, inactivity));
979 * Kills the oldest connection that is in TIME_WAIT state.
980 * Called from tcp_alloc() if no more connections are available.
983 tcp_kill_timewait(void)
985 struct tcp_pcb *pcb, *inactive;
990 /* Go through the list of TIME_WAIT pcbs and get the oldest pcb. */
991 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
992 if ((u32_t)(tcp_ticks - pcb->tmr) >= inactivity) {
993 inactivity = tcp_ticks - pcb->tmr;
997 if (inactive != NULL) {
998 LWIP_DEBUGF(TCP_DEBUG, ("tcp_kill_timewait: killing oldest TIME-WAIT PCB %p (%"S32_F")\n",
999 (void *)inactive, inactivity));
1000 tcp_abort(inactive);
1005 * Allocate a new tcp_pcb structure.
1007 * @param prio priority for the new pcb
1008 * @return a new tcp_pcb that initially is in state CLOSED
1011 tcp_alloc(u8_t prio)
1013 struct tcp_pcb *pcb;
1016 pcb = memp_malloc(MEMP_TCP_PCB);
1018 /* Try killing oldest connection in TIME-WAIT. */
1019 LWIP_DEBUGF(TCP_DEBUG, ("tcp_alloc: killing off oldest TIME-WAIT connection\n"));
1020 tcp_kill_timewait();
1021 /* Try to allocate a tcp_pcb again. */
1022 pcb = memp_malloc(MEMP_TCP_PCB);
1024 /* Try killing active connections with lower priority than the new one. */
1025 LWIP_DEBUGF(TCP_DEBUG, ("tcp_alloc: killing connection with prio lower than %d\n", prio));
1026 tcp_kill_prio(prio);
1027 /* Try to allocate a tcp_pcb again. */
1028 pcb = memp_malloc(MEMP_TCP_PCB);
1030 /* adjust err stats: memp_malloc failed twice before */
1031 MEMP_STATS_DEC(err, MEMP_TCP_PCB);
1035 /* adjust err stats: timewait PCB was freed above */
1036 MEMP_STATS_DEC(err, MEMP_TCP_PCB);
1040 memset(pcb, 0, sizeof(struct tcp_pcb));
1041 pcb->prio = TCP_PRIO_NORMAL;
1042 pcb->snd_buf = TCP_SND_BUF;
1043 pcb->snd_queuelen = 0;
1044 pcb->rcv_wnd = TCP_WND;
1045 pcb->rcv_ann_wnd = TCP_WND;
1048 /* As initial send MSS, we use TCP_MSS but limit it to 536.
1049 The send MSS is updated when an MSS option is received. */
1050 pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS;
1051 pcb->rto = 3000 / TCP_SLOW_INTERVAL;
1053 pcb->sv = 3000 / TCP_SLOW_INTERVAL;
1056 iss = tcp_next_iss();
1061 pcb->tmr = tcp_ticks;
1065 #if LWIP_CALLBACK_API
1066 pcb->recv = tcp_recv_null;
1067 #endif /* LWIP_CALLBACK_API */
1069 /* Init KEEPALIVE timer */
1070 pcb->keep_idle = TCP_KEEPIDLE_DEFAULT;
1072 #if LWIP_TCP_KEEPALIVE
1073 pcb->keep_intvl = TCP_KEEPINTVL_DEFAULT;
1074 pcb->keep_cnt = TCP_KEEPCNT_DEFAULT;
1075 #endif /* LWIP_TCP_KEEPALIVE */
1077 pcb->keep_cnt_sent = 0;
1083 * Creates a new TCP protocol control block but doesn't place it on
1084 * any of the TCP PCB lists.
1085 * The pcb is not put on any list until binding using tcp_bind().
1087 * @internal: Maybe there should be a idle TCP PCB list where these
1088 * PCBs are put on. Port reservation using tcp_bind() is implemented but
1089 * allocated pcbs that are not bound can't be killed automatically if wanting
1090 * to allocate a pcb with higher prio (@see tcp_kill_prio())
1092 * @return a new tcp_pcb that initially is in state CLOSED
1097 return tcp_alloc(TCP_PRIO_NORMAL);
1101 * Used to specify the argument that should be passed callback
1104 * @param pcb tcp_pcb to set the callback argument
1105 * @param arg void pointer argument to pass to callback functions
1108 tcp_arg(struct tcp_pcb *pcb, void *arg)
1110 pcb->callback_arg = arg;
1112 #if LWIP_CALLBACK_API
1115 * Used to specify the function that should be called when a TCP
1116 * connection receives data.
1118 * @param pcb tcp_pcb to set the recv callback
1119 * @param recv callback function to call for this pcb when data is received
1122 tcp_recv(struct tcp_pcb *pcb, tcp_recv_fn recv)
1128 * Used to specify the function that should be called when TCP data
1129 * has been successfully delivered to the remote host.
1131 * @param pcb tcp_pcb to set the sent callback
1132 * @param sent callback function to call for this pcb when data is successfully sent
1135 tcp_sent(struct tcp_pcb *pcb, tcp_sent_fn sent)
1141 * Used to specify the function that should be called when a fatal error
1142 * has occured on the connection.
1144 * @param pcb tcp_pcb to set the err callback
1145 * @param err callback function to call for this pcb when a fatal error
1146 * has occured on the connection
1149 tcp_err(struct tcp_pcb *pcb, tcp_err_fn err)
1155 * Used for specifying the function that should be called when a
1156 * LISTENing connection has been connected to another host.
1158 * @param pcb tcp_pcb to set the accept callback
1159 * @param accept callback function to call for this pcb when LISTENing
1160 * connection has been connected to another host
1163 tcp_accept(struct tcp_pcb *pcb, tcp_accept_fn accept)
1165 pcb->accept = accept;
1167 #endif /* LWIP_CALLBACK_API */
1171 * Used to specify the function that should be called periodically
1172 * from TCP. The interval is specified in terms of the TCP coarse
1173 * timer interval, which is called twice a second.
1177 tcp_poll(struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval)
1179 #if LWIP_CALLBACK_API
1181 #endif /* LWIP_CALLBACK_API */
1182 pcb->pollinterval = interval;
1186 * Purges a TCP PCB. Removes any buffered data and frees the buffer memory
1187 * (pcb->ooseq, pcb->unsent and pcb->unacked are freed).
1189 * @param pcb tcp_pcb to purge. The pcb itself is not deallocated!
1192 tcp_pcb_purge(struct tcp_pcb *pcb)
1194 if (pcb->state != CLOSED &&
1195 pcb->state != TIME_WAIT &&
1196 pcb->state != LISTEN) {
1198 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge\n"));
1200 #if TCP_LISTEN_BACKLOG
1201 if (pcb->state == SYN_RCVD) {
1202 /* Need to find the corresponding listen_pcb and decrease its accepts_pending */
1203 struct tcp_pcb_listen *lpcb;
1204 LWIP_ASSERT("tcp_pcb_purge: pcb->state == SYN_RCVD but tcp_listen_pcbs is NULL",
1205 tcp_listen_pcbs.listen_pcbs != NULL);
1206 for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
1207 if ((lpcb->local_port == pcb->local_port) &&
1208 (ip_addr_isany(&lpcb->local_ip) ||
1209 ip_addr_cmp(&pcb->local_ip, &lpcb->local_ip))) {
1210 /* port and address of the listen pcb match the timed-out pcb */
1211 LWIP_ASSERT("tcp_pcb_purge: listen pcb does not have accepts pending",
1212 lpcb->accepts_pending > 0);
1213 lpcb->accepts_pending--;
1218 #endif /* TCP_LISTEN_BACKLOG */
1221 if (pcb->refused_data != NULL) {
1222 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->refused_data\n"));
1223 pbuf_free(pcb->refused_data);
1224 pcb->refused_data = NULL;
1226 if (pcb->unsent != NULL) {
1227 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: not all data sent\n"));
1229 if (pcb->unacked != NULL) {
1230 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->unacked\n"));
1232 #if TCP_QUEUE_OOSEQ /* LW */
1233 if (pcb->ooseq != NULL) {
1234 LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->ooseq\n"));
1236 tcp_segs_free(pcb->ooseq);
1238 #endif /* TCP_QUEUE_OOSEQ */
1240 /* Stop the retransmission timer as it will expect data on unacked
1241 queue if it fires */
1244 tcp_segs_free(pcb->unsent);
1245 tcp_segs_free(pcb->unacked);
1246 pcb->unacked = pcb->unsent = NULL;
1251 * Purges the PCB and removes it from a PCB list. Any delayed ACKs are sent first.
1253 * @param pcblist PCB list to purge.
1254 * @param pcb tcp_pcb to purge. The pcb itself is NOT deallocated!
1257 tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb)
1259 TCP_RMV(pcblist, pcb);
1263 /* if there is an outstanding delayed ACKs, send it */
1264 if (pcb->state != TIME_WAIT &&
1265 pcb->state != LISTEN &&
1266 pcb->flags & TF_ACK_DELAY) {
1267 pcb->flags |= TF_ACK_NOW;
1271 if (pcb->state != LISTEN) {
1272 LWIP_ASSERT("unsent segments leaking", pcb->unsent == NULL);
1273 LWIP_ASSERT("unacked segments leaking", pcb->unacked == NULL);
1275 LWIP_ASSERT("ooseq segments leaking", pcb->ooseq == NULL);
1276 #endif /* TCP_QUEUE_OOSEQ */
1279 pcb->state = CLOSED;
1281 LWIP_ASSERT("tcp_pcb_remove: tcp_pcbs_sane()", tcp_pcbs_sane());
1285 * Calculates a new initial sequence number for new connections.
1287 * @return u32_t pseudo random sequence number
1292 static u32_t iss = 6510;
1294 iss += tcp_ticks; /* XXX */
1298 #if TCP_CALCULATE_EFF_SEND_MSS
1300 * Calcluates the effective send mss that can be used for a specific IP address
1301 * by using ip_route to determin the netif used to send to the address and
1302 * calculating the minimum of TCP_MSS and that netif's mtu (if set).
1305 tcp_eff_send_mss(u16_t sendmss, struct ip_addr *addr)
1308 struct netif *outif;
1310 outif = ip_route(addr);
1311 if ((outif != NULL) && (outif->mtu != 0)) {
1312 mss_s = outif->mtu - IP_HLEN - TCP_HLEN;
1313 /* RFC 1122, chap 4.2.2.6:
1314 * Eff.snd.MSS = min(SendMSS+20, MMS_S) - TCPhdrsize - IPoptionsize
1315 * We correct for TCP options in tcp_enqueue(), and don't support
1318 sendmss = LWIP_MIN(sendmss, mss_s);
1322 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
1325 tcp_debug_state_str(enum tcp_state s)
1327 return tcp_state_str[s];
1330 #if TCP_DEBUG || TCP_INPUT_DEBUG || TCP_OUTPUT_DEBUG
1332 * Print a tcp header for debugging purposes.
1334 * @param tcphdr pointer to a struct tcp_hdr
1337 tcp_debug_print(struct tcp_hdr *tcphdr)
1339 LWIP_DEBUGF(TCP_DEBUG, ("TCP header:\n"));
1340 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1341 LWIP_DEBUGF(TCP_DEBUG, ("| %5"U16_F" | %5"U16_F" | (src port, dest port)\n",
1342 ntohs(tcphdr->src), ntohs(tcphdr->dest)));
1343 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1344 LWIP_DEBUGF(TCP_DEBUG, ("| %010"U32_F" | (seq no)\n",
1345 ntohl(tcphdr->seqno)));
1346 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1347 LWIP_DEBUGF(TCP_DEBUG, ("| %010"U32_F" | (ack no)\n",
1348 ntohl(tcphdr->ackno)));
1349 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1350 LWIP_DEBUGF(TCP_DEBUG, ("| %2"U16_F" | |%"U16_F"%"U16_F"%"U16_F"%"U16_F"%"U16_F"%"U16_F"| %5"U16_F" | (hdrlen, flags (",
1351 TCPH_HDRLEN(tcphdr),
1352 TCPH_FLAGS(tcphdr) >> 5 & 1,
1353 TCPH_FLAGS(tcphdr) >> 4 & 1,
1354 TCPH_FLAGS(tcphdr) >> 3 & 1,
1355 TCPH_FLAGS(tcphdr) >> 2 & 1,
1356 TCPH_FLAGS(tcphdr) >> 1 & 1,
1357 TCPH_FLAGS(tcphdr) & 1,
1358 ntohs(tcphdr->wnd)));
1359 tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
1360 LWIP_DEBUGF(TCP_DEBUG, ("), win)\n"));
1361 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1362 LWIP_DEBUGF(TCP_DEBUG, ("| 0x%04"X16_F" | %5"U16_F" | (chksum, urgp)\n",
1363 ntohs(tcphdr->chksum), ntohs(tcphdr->urgp)));
1364 LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n"));
1368 * Print a tcp state for debugging purposes.
1370 * @param s enum tcp_state to print
1373 tcp_debug_print_state(enum tcp_state s)
1375 LWIP_DEBUGF(TCP_DEBUG, ("State: %s\n", tcp_state_str[s]));
1379 * Print tcp flags for debugging purposes.
1381 * @param flags tcp flags, all active flags are printed
1384 tcp_debug_print_flags(u8_t flags)
1386 if (flags & TCP_FIN) {
1387 LWIP_DEBUGF(TCP_DEBUG, ("FIN "));
1389 if (flags & TCP_SYN) {
1390 LWIP_DEBUGF(TCP_DEBUG, ("SYN "));
1392 if (flags & TCP_RST) {
1393 LWIP_DEBUGF(TCP_DEBUG, ("RST "));
1395 if (flags & TCP_PSH) {
1396 LWIP_DEBUGF(TCP_DEBUG, ("PSH "));
1398 if (flags & TCP_ACK) {
1399 LWIP_DEBUGF(TCP_DEBUG, ("ACK "));
1401 if (flags & TCP_URG) {
1402 LWIP_DEBUGF(TCP_DEBUG, ("URG "));
1404 if (flags & TCP_ECE) {
1405 LWIP_DEBUGF(TCP_DEBUG, ("ECE "));
1407 if (flags & TCP_CWR) {
1408 LWIP_DEBUGF(TCP_DEBUG, ("CWR "));
1410 LWIP_DEBUGF(TCP_DEBUG, ("\n"));
1414 * Print all tcp_pcbs in every list for debugging purposes.
1417 tcp_debug_print_pcbs(void)
1419 struct tcp_pcb *pcb;
1420 LWIP_DEBUGF(TCP_DEBUG, ("Active PCB states:\n"));
1421 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
1422 LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
1423 pcb->local_port, pcb->remote_port,
1424 pcb->snd_nxt, pcb->rcv_nxt));
1425 tcp_debug_print_state(pcb->state);
1427 LWIP_DEBUGF(TCP_DEBUG, ("Listen PCB states:\n"));
1428 for(pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next) {
1429 LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
1430 pcb->local_port, pcb->remote_port,
1431 pcb->snd_nxt, pcb->rcv_nxt));
1432 tcp_debug_print_state(pcb->state);
1434 LWIP_DEBUGF(TCP_DEBUG, ("TIME-WAIT PCB states:\n"));
1435 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
1436 LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
1437 pcb->local_port, pcb->remote_port,
1438 pcb->snd_nxt, pcb->rcv_nxt));
1439 tcp_debug_print_state(pcb->state);
1444 * Check state consistency of the tcp_pcb lists.
1449 struct tcp_pcb *pcb;
1450 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
1451 LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != CLOSED", pcb->state != CLOSED);
1452 LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != LISTEN", pcb->state != LISTEN);
1453 LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
1455 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
1456 LWIP_ASSERT("tcp_pcbs_sane: tw pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
1460 #endif /* TCP_DEBUG */
1462 #endif /* LWIP_TCP */