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 (at) 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 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 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 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 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 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 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 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 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 * 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 */ 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 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 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 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 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 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 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 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 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 * 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 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 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 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 * 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 * 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 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 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 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 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 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 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 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 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 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 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* 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 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 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 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 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 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
