Travis Geiselbrecht | 1d0df69 | 2008-09-01 02:26:09 -0700 | [diff] [blame^] | 1 | /** |
| 2 | * @file |
| 3 | * |
| 4 | * Transmission Control Protocol, incoming traffic |
| 5 | * |
| 6 | * The input processing functions of TCP. |
| 7 | * |
| 8 | * These functions are generally called in the order (ip_input() ->) tcp_input() -> |
| 9 | * tcp_process() -> tcp_receive() (-> application). |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | /* |
| 14 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science. |
| 15 | * All rights reserved. |
| 16 | * |
| 17 | * Redistribution and use in source and binary forms, with or without modification, |
| 18 | * are permitted provided that the following conditions are met: |
| 19 | * |
| 20 | * 1. Redistributions of source code must retain the above copyright notice, |
| 21 | * this list of conditions and the following disclaimer. |
| 22 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 23 | * this list of conditions and the following disclaimer in the documentation |
| 24 | * and/or other materials provided with the distribution. |
| 25 | * 3. The name of the author may not be used to endorse or promote products |
| 26 | * derived from this software without specific prior written permission. |
| 27 | * |
| 28 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 29 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 30 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT |
| 31 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 32 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 33 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 34 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 35 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
| 36 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY |
| 37 | * OF SUCH DAMAGE. |
| 38 | * |
| 39 | * This file is part of the lwIP TCP/IP stack. |
| 40 | * |
| 41 | * Author: Adam Dunkels <adam@sics.se> |
| 42 | * |
| 43 | */ |
| 44 | |
| 45 | #include "lwip/def.h" |
| 46 | #include "lwip/opt.h" |
| 47 | |
| 48 | #include "lwip/ip_addr.h" |
| 49 | #include "lwip/netif.h" |
| 50 | #include "lwip/mem.h" |
| 51 | #include "lwip/memp.h" |
| 52 | |
| 53 | #include "lwip/inet.h" |
| 54 | #include "lwip/tcp.h" |
| 55 | |
| 56 | #include "lwip/stats.h" |
| 57 | |
| 58 | #include "arch/perf.h" |
| 59 | #if LWIP_TCP |
| 60 | /* These variables are global to all functions involved in the input |
| 61 | processing of TCP segments. They are set by the tcp_input() |
| 62 | function. */ |
| 63 | static struct tcp_seg inseg; |
| 64 | static struct tcp_hdr *tcphdr; |
| 65 | static struct ip_hdr *iphdr; |
| 66 | static u32_t seqno, ackno; |
| 67 | static u8_t flags; |
| 68 | static u16_t tcplen; |
| 69 | |
| 70 | static u8_t recv_flags; |
| 71 | static struct pbuf *recv_data; |
| 72 | |
| 73 | struct tcp_pcb *tcp_input_pcb; |
| 74 | |
| 75 | /* Forward declarations. */ |
| 76 | static err_t tcp_process(struct tcp_pcb *pcb); |
| 77 | static void tcp_receive(struct tcp_pcb *pcb); |
| 78 | static void tcp_parseopt(struct tcp_pcb *pcb); |
| 79 | |
| 80 | static err_t tcp_listen_input(struct tcp_pcb_listen *pcb); |
| 81 | static err_t tcp_timewait_input(struct tcp_pcb *pcb); |
| 82 | |
| 83 | |
| 84 | /* tcp_input: |
| 85 | * |
| 86 | * The initial input processing of TCP. It verifies the TCP header, demultiplexes |
| 87 | * the segment between the PCBs and passes it on to tcp_process(), which implements |
| 88 | * the TCP finite state machine. This function is called by the IP layer (in |
| 89 | * ip_input()). |
| 90 | */ |
| 91 | |
| 92 | void |
| 93 | tcp_input(struct pbuf *p, struct netif *inp) |
| 94 | { |
| 95 | struct tcp_pcb *pcb, *prev; |
| 96 | struct tcp_pcb_listen *lpcb; |
| 97 | u8_t hdrlen; |
| 98 | err_t err; |
| 99 | |
| 100 | PERF_START; |
| 101 | |
| 102 | TCP_STATS_INC(tcp.recv); |
| 103 | |
| 104 | iphdr = p->payload; |
| 105 | tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4); |
| 106 | |
| 107 | #if TCP_INPUT_DEBUG |
| 108 | tcp_debug_print(tcphdr); |
| 109 | #endif |
| 110 | |
| 111 | /* remove header from payload */ |
| 112 | if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) { |
| 113 | /* drop short packets */ |
| 114 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len)); |
| 115 | TCP_STATS_INC(tcp.lenerr); |
| 116 | TCP_STATS_INC(tcp.drop); |
| 117 | pbuf_free(p); |
| 118 | return; |
| 119 | } |
| 120 | |
| 121 | /* Don't even process incoming broadcasts/multicasts. */ |
| 122 | if (ip_addr_isbroadcast(&(iphdr->dest), inp) || |
| 123 | ip_addr_ismulticast(&(iphdr->dest))) { |
| 124 | pbuf_free(p); |
| 125 | return; |
| 126 | } |
| 127 | |
| 128 | #if CHECKSUM_CHECK_TCP |
| 129 | /* Verify TCP checksum. */ |
| 130 | if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src), |
| 131 | (struct ip_addr *)&(iphdr->dest), |
| 132 | IP_PROTO_TCP, p->tot_len) != 0) { |
| 133 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n", |
| 134 | inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src), (struct ip_addr *)&(iphdr->dest), |
| 135 | IP_PROTO_TCP, p->tot_len))); |
| 136 | #if TCP_DEBUG |
| 137 | tcp_debug_print(tcphdr); |
| 138 | #endif /* TCP_DEBUG */ |
| 139 | TCP_STATS_INC(tcp.chkerr); |
| 140 | TCP_STATS_INC(tcp.drop); |
| 141 | |
| 142 | pbuf_free(p); |
| 143 | return; |
| 144 | } |
| 145 | #endif |
| 146 | |
| 147 | /* Move the payload pointer in the pbuf so that it points to the |
| 148 | TCP data instead of the TCP header. */ |
| 149 | hdrlen = TCPH_HDRLEN(tcphdr); |
| 150 | pbuf_header(p, -(hdrlen * 4)); |
| 151 | |
| 152 | /* Convert fields in TCP header to host byte order. */ |
| 153 | tcphdr->src = ntohs(tcphdr->src); |
| 154 | tcphdr->dest = ntohs(tcphdr->dest); |
| 155 | seqno = tcphdr->seqno = ntohl(tcphdr->seqno); |
| 156 | ackno = tcphdr->ackno = ntohl(tcphdr->ackno); |
| 157 | tcphdr->wnd = ntohs(tcphdr->wnd); |
| 158 | |
| 159 | flags = TCPH_FLAGS(tcphdr) & TCP_FLAGS; |
| 160 | tcplen = p->tot_len + ((flags & TCP_FIN || flags & TCP_SYN)? 1: 0); |
| 161 | |
| 162 | /* Demultiplex an incoming segment. First, we check if it is destined |
| 163 | for an active connection. */ |
| 164 | prev = NULL; |
| 165 | |
| 166 | |
| 167 | for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) { |
| 168 | LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED); |
| 169 | LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT); |
| 170 | LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN); |
| 171 | if (pcb->remote_port == tcphdr->src && |
| 172 | pcb->local_port == tcphdr->dest && |
| 173 | ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) && |
| 174 | ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) { |
| 175 | |
| 176 | /* Move this PCB to the front of the list so that subsequent |
| 177 | lookups will be faster (we exploit locality in TCP segment |
| 178 | arrivals). */ |
| 179 | LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb); |
| 180 | if (prev != NULL) { |
| 181 | prev->next = pcb->next; |
| 182 | pcb->next = tcp_active_pcbs; |
| 183 | tcp_active_pcbs = pcb; |
| 184 | } |
| 185 | LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb); |
| 186 | break; |
| 187 | } |
| 188 | prev = pcb; |
| 189 | } |
| 190 | |
| 191 | if (pcb == NULL) { |
| 192 | /* If it did not go to an active connection, we check the connections |
| 193 | in the TIME-WAIT state. */ |
| 194 | |
| 195 | for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) { |
| 196 | LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT); |
| 197 | if (pcb->remote_port == tcphdr->src && |
| 198 | pcb->local_port == tcphdr->dest && |
| 199 | ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) && |
| 200 | ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) { |
| 201 | /* We don't really care enough to move this PCB to the front |
| 202 | of the list since we are not very likely to receive that |
| 203 | many segments for connections in TIME-WAIT. */ |
| 204 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n")); |
| 205 | tcp_timewait_input(pcb); |
| 206 | pbuf_free(p); |
| 207 | return; |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | /* Finally, if we still did not get a match, we check all PCBs that |
| 212 | are LISTENing for incoming connections. */ |
| 213 | prev = NULL; |
| 214 | for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) { |
| 215 | if ((ip_addr_isany(&(lpcb->local_ip)) || |
| 216 | ip_addr_cmp(&(lpcb->local_ip), &(iphdr->dest))) && |
| 217 | lpcb->local_port == tcphdr->dest) { |
| 218 | /* Move this PCB to the front of the list so that subsequent |
| 219 | lookups will be faster (we exploit locality in TCP segment |
| 220 | arrivals). */ |
| 221 | if (prev != NULL) { |
| 222 | ((struct tcp_pcb_listen *)prev)->next = lpcb->next; |
| 223 | /* our successor is the remainder of the listening list */ |
| 224 | lpcb->next = tcp_listen_pcbs.listen_pcbs; |
| 225 | /* put this listening pcb at the head of the listening list */ |
| 226 | tcp_listen_pcbs.listen_pcbs = lpcb; |
| 227 | } |
| 228 | |
| 229 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n")); |
| 230 | tcp_listen_input(lpcb); |
| 231 | pbuf_free(p); |
| 232 | return; |
| 233 | } |
| 234 | prev = (struct tcp_pcb *)lpcb; |
| 235 | } |
| 236 | } |
| 237 | |
| 238 | #if TCP_INPUT_DEBUG |
| 239 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags ")); |
| 240 | tcp_debug_print_flags(TCPH_FLAGS(tcphdr)); |
| 241 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n")); |
| 242 | #endif /* TCP_INPUT_DEBUG */ |
| 243 | |
| 244 | |
| 245 | if (pcb != NULL) { |
| 246 | /* The incoming segment belongs to a connection. */ |
| 247 | #if TCP_INPUT_DEBUG |
| 248 | #if TCP_DEBUG |
| 249 | tcp_debug_print_state(pcb->state); |
| 250 | #endif /* TCP_DEBUG */ |
| 251 | #endif /* TCP_INPUT_DEBUG */ |
| 252 | |
| 253 | /* Set up a tcp_seg structure. */ |
| 254 | inseg.next = NULL; |
| 255 | inseg.len = p->tot_len; |
| 256 | inseg.dataptr = p->payload; |
| 257 | inseg.p = p; |
| 258 | inseg.tcphdr = tcphdr; |
| 259 | |
| 260 | recv_data = NULL; |
| 261 | recv_flags = 0; |
| 262 | |
| 263 | tcp_input_pcb = pcb; |
| 264 | err = tcp_process(pcb); |
| 265 | tcp_input_pcb = NULL; |
| 266 | /* A return value of ERR_ABRT means that tcp_abort() was called |
| 267 | and that the pcb has been freed. If so, we don't do anything. */ |
| 268 | if (err != ERR_ABRT) { |
| 269 | if (recv_flags & TF_RESET) { |
| 270 | /* TF_RESET means that the connection was reset by the other |
| 271 | end. We then call the error callback to inform the |
| 272 | application that the connection is dead before we |
| 273 | deallocate the PCB. */ |
| 274 | TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST); |
| 275 | tcp_pcb_remove(&tcp_active_pcbs, pcb); |
| 276 | memp_free(MEMP_TCP_PCB, pcb); |
| 277 | } else if (recv_flags & TF_CLOSED) { |
| 278 | /* The connection has been closed and we will deallocate the |
| 279 | PCB. */ |
| 280 | tcp_pcb_remove(&tcp_active_pcbs, pcb); |
| 281 | memp_free(MEMP_TCP_PCB, pcb); |
| 282 | } else { |
| 283 | err = ERR_OK; |
| 284 | /* If the application has registered a "sent" function to be |
| 285 | called when new send buffer space is available, we call it |
| 286 | now. */ |
| 287 | if (pcb->acked > 0) { |
| 288 | TCP_EVENT_SENT(pcb, pcb->acked, err); |
| 289 | } |
| 290 | |
| 291 | if (recv_data != NULL) { |
| 292 | /* Notify application that data has been received. */ |
| 293 | TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err); |
| 294 | } |
| 295 | |
| 296 | /* If a FIN segment was received, we call the callback |
| 297 | function with a NULL buffer to indicate EOF. */ |
| 298 | if (recv_flags & TF_GOT_FIN) { |
| 299 | TCP_EVENT_RECV(pcb, NULL, ERR_OK, err); |
| 300 | } |
| 301 | /* If there were no errors, we try to send something out. */ |
| 302 | if (err == ERR_OK) { |
| 303 | tcp_output(pcb); |
| 304 | } |
| 305 | } |
| 306 | } |
| 307 | |
| 308 | |
| 309 | /* We deallocate the incoming pbuf. If it was buffered by the |
| 310 | application, the application should have called pbuf_ref() to |
| 311 | increase the reference counter in the pbuf. If so, the buffer |
| 312 | isn't actually deallocated by the call to pbuf_free(), only the |
| 313 | reference count is decreased. */ |
| 314 | if (inseg.p != NULL) pbuf_free(inseg.p); |
| 315 | #if TCP_INPUT_DEBUG |
| 316 | #if TCP_DEBUG |
| 317 | tcp_debug_print_state(pcb->state); |
| 318 | #endif /* TCP_DEBUG */ |
| 319 | #endif /* TCP_INPUT_DEBUG */ |
| 320 | |
| 321 | } else { |
| 322 | |
| 323 | /* If no matching PCB was found, send a TCP RST (reset) to the |
| 324 | sender. */ |
| 325 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n")); |
| 326 | if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) { |
| 327 | TCP_STATS_INC(tcp.proterr); |
| 328 | TCP_STATS_INC(tcp.drop); |
| 329 | tcp_rst(ackno, seqno + tcplen, |
| 330 | &(iphdr->dest), &(iphdr->src), |
| 331 | tcphdr->dest, tcphdr->src); |
| 332 | } |
| 333 | pbuf_free(p); |
| 334 | } |
| 335 | |
| 336 | LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane()); |
| 337 | PERF_STOP("tcp_input"); |
| 338 | } |
| 339 | |
| 340 | /* tcp_listen_input(): |
| 341 | * |
| 342 | * Called by tcp_input() when a segment arrives for a listening |
| 343 | * connection. |
| 344 | */ |
| 345 | |
| 346 | static err_t |
| 347 | tcp_listen_input(struct tcp_pcb_listen *pcb) |
| 348 | { |
| 349 | struct tcp_pcb *npcb; |
| 350 | u32_t optdata; |
| 351 | |
| 352 | /* In the LISTEN state, we check for incoming SYN segments, |
| 353 | creates a new PCB, and responds with a SYN|ACK. */ |
| 354 | if (flags & TCP_ACK) { |
| 355 | /* For incoming segments with the ACK flag set, respond with a |
| 356 | RST. */ |
| 357 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n")); |
| 358 | tcp_rst(ackno + 1, seqno + tcplen, |
| 359 | &(iphdr->dest), &(iphdr->src), |
| 360 | tcphdr->dest, tcphdr->src); |
| 361 | } else if (flags & TCP_SYN) { |
| 362 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest)); |
| 363 | npcb = tcp_alloc(pcb->prio); |
| 364 | /* If a new PCB could not be created (probably due to lack of memory), |
| 365 | we don't do anything, but rely on the sender will retransmit the |
| 366 | SYN at a time when we have more memory available. */ |
| 367 | if (npcb == NULL) { |
| 368 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n")); |
| 369 | TCP_STATS_INC(tcp.memerr); |
| 370 | return ERR_MEM; |
| 371 | } |
| 372 | /* Set up the new PCB. */ |
| 373 | ip_addr_set(&(npcb->local_ip), &(iphdr->dest)); |
| 374 | npcb->local_port = pcb->local_port; |
| 375 | ip_addr_set(&(npcb->remote_ip), &(iphdr->src)); |
| 376 | npcb->remote_port = tcphdr->src; |
| 377 | npcb->state = SYN_RCVD; |
| 378 | npcb->rcv_nxt = seqno + 1; |
| 379 | npcb->snd_wnd = tcphdr->wnd; |
| 380 | npcb->ssthresh = npcb->snd_wnd; |
| 381 | npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */ |
| 382 | npcb->callback_arg = pcb->callback_arg; |
| 383 | #if LWIP_CALLBACK_API |
| 384 | npcb->accept = pcb->accept; |
| 385 | #endif /* LWIP_CALLBACK_API */ |
| 386 | /* inherit socket options */ |
| 387 | npcb->so_options = pcb->so_options & (SOF_DEBUG|SOF_DONTROUTE|SOF_KEEPALIVE|SOF_OOBINLINE|SOF_LINGER); |
| 388 | /* Register the new PCB so that we can begin receiving segments |
| 389 | for it. */ |
| 390 | TCP_REG(&tcp_active_pcbs, npcb); |
| 391 | |
| 392 | /* Parse any options in the SYN. */ |
| 393 | tcp_parseopt(npcb); |
| 394 | |
| 395 | /* Build an MSS option. */ |
| 396 | optdata = htonl(((u32_t)2 << 24) | |
| 397 | ((u32_t)4 << 16) | |
| 398 | (((u32_t)npcb->mss / 256) << 8) | |
| 399 | (npcb->mss & 255)); |
| 400 | /* Send a SYN|ACK together with the MSS option. */ |
| 401 | tcp_enqueue(npcb, NULL, 0, TCP_SYN | TCP_ACK, 0, (u8_t *)&optdata, 4); |
| 402 | return tcp_output(npcb); |
| 403 | } |
| 404 | return ERR_OK; |
| 405 | } |
| 406 | |
| 407 | /* tcp_timewait_input(): |
| 408 | * |
| 409 | * Called by tcp_input() when a segment arrives for a connection in |
| 410 | * TIME_WAIT. |
| 411 | */ |
| 412 | |
| 413 | static err_t |
| 414 | tcp_timewait_input(struct tcp_pcb *pcb) |
| 415 | { |
| 416 | if (TCP_SEQ_GT(seqno + tcplen, pcb->rcv_nxt)) { |
| 417 | pcb->rcv_nxt = seqno + tcplen; |
| 418 | } |
| 419 | if (tcplen > 0) { |
| 420 | tcp_ack_now(pcb); |
| 421 | } |
| 422 | return tcp_output(pcb); |
| 423 | } |
| 424 | |
| 425 | /* tcp_process |
| 426 | * |
| 427 | * Implements the TCP state machine. Called by tcp_input. In some |
| 428 | * states tcp_receive() is called to receive data. The tcp_seg |
| 429 | * argument will be freed by the caller (tcp_input()) unless the |
| 430 | * recv_data pointer in the pcb is set. |
| 431 | */ |
| 432 | |
| 433 | static err_t |
| 434 | tcp_process(struct tcp_pcb *pcb) |
| 435 | { |
| 436 | struct tcp_seg *rseg; |
| 437 | u8_t acceptable = 0; |
| 438 | err_t err; |
| 439 | |
| 440 | |
| 441 | err = ERR_OK; |
| 442 | |
| 443 | /* Process incoming RST segments. */ |
| 444 | if (flags & TCP_RST) { |
| 445 | /* First, determine if the reset is acceptable. */ |
| 446 | if (pcb->state == SYN_SENT) { |
| 447 | if (ackno == pcb->snd_nxt) { |
| 448 | acceptable = 1; |
| 449 | } |
| 450 | } else { |
| 451 | /*if (TCP_SEQ_GEQ(seqno, pcb->rcv_nxt) && |
| 452 | TCP_SEQ_LEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) { |
| 453 | */ |
| 454 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) { |
| 455 | acceptable = 1; |
| 456 | } |
| 457 | } |
| 458 | |
| 459 | if (acceptable) { |
| 460 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n")); |
| 461 | LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED); |
| 462 | recv_flags = TF_RESET; |
| 463 | pcb->flags &= ~TF_ACK_DELAY; |
| 464 | return ERR_RST; |
| 465 | } else { |
| 466 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n", |
| 467 | seqno, pcb->rcv_nxt)); |
| 468 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n", |
| 469 | seqno, pcb->rcv_nxt)); |
| 470 | return ERR_OK; |
| 471 | } |
| 472 | } |
| 473 | |
| 474 | /* Update the PCB (in)activity timer. */ |
| 475 | pcb->tmr = tcp_ticks; |
| 476 | pcb->keep_cnt = 0; |
| 477 | |
| 478 | /* Do different things depending on the TCP state. */ |
| 479 | switch (pcb->state) { |
| 480 | case SYN_SENT: |
| 481 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno, |
| 482 | pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno))); |
| 483 | /* received SYN ACK with expected sequence number? */ |
| 484 | if ((flags & TCP_ACK) && (flags & TCP_SYN) |
| 485 | && ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) { |
| 486 | pcb->snd_buf++; |
| 487 | pcb->rcv_nxt = seqno + 1; |
| 488 | pcb->lastack = ackno; |
| 489 | pcb->snd_wnd = tcphdr->wnd; |
| 490 | pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */ |
| 491 | pcb->state = ESTABLISHED; |
| 492 | pcb->cwnd = pcb->mss; |
| 493 | --pcb->snd_queuelen; |
| 494 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen)); |
| 495 | rseg = pcb->unacked; |
| 496 | pcb->unacked = rseg->next; |
| 497 | tcp_seg_free(rseg); |
| 498 | |
| 499 | /* Parse any options in the SYNACK. */ |
| 500 | tcp_parseopt(pcb); |
| 501 | |
| 502 | /* Call the user specified function to call when sucessfully |
| 503 | * connected. */ |
| 504 | TCP_EVENT_CONNECTED(pcb, ERR_OK, err); |
| 505 | tcp_ack(pcb); |
| 506 | } |
| 507 | /* received ACK? possibly a half-open connection */ |
| 508 | else if (flags & TCP_ACK) { |
| 509 | /* send a RST to bring the other side in a non-synchronized state. */ |
| 510 | tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src), |
| 511 | tcphdr->dest, tcphdr->src); |
| 512 | } |
| 513 | break; |
| 514 | case SYN_RCVD: |
| 515 | if (flags & TCP_ACK && |
| 516 | !(flags & TCP_RST)) { |
| 517 | /* expected ACK number? */ |
| 518 | if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) { |
| 519 | pcb->state = ESTABLISHED; |
| 520 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest)); |
| 521 | #if LWIP_CALLBACK_API |
| 522 | LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL); |
| 523 | #endif |
| 524 | /* Call the accept function. */ |
| 525 | TCP_EVENT_ACCEPT(pcb, ERR_OK, err); |
| 526 | if (err != ERR_OK) { |
| 527 | /* If the accept function returns with an error, we abort |
| 528 | * the connection. */ |
| 529 | tcp_abort(pcb); |
| 530 | return ERR_ABRT; |
| 531 | } |
| 532 | /* If there was any data contained within this ACK, |
| 533 | * we'd better pass it on to the application as well. */ |
| 534 | tcp_receive(pcb); |
| 535 | pcb->cwnd = pcb->mss; |
| 536 | } |
| 537 | /* incorrect ACK number */ |
| 538 | else { |
| 539 | /* send RST */ |
| 540 | tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src), |
| 541 | tcphdr->dest, tcphdr->src); |
| 542 | } |
| 543 | } |
| 544 | break; |
| 545 | case CLOSE_WAIT: |
| 546 | /* FALLTHROUGH */ |
| 547 | case ESTABLISHED: |
| 548 | tcp_receive(pcb); |
| 549 | if (flags & TCP_FIN) { |
| 550 | tcp_ack_now(pcb); |
| 551 | pcb->state = CLOSE_WAIT; |
| 552 | } |
| 553 | break; |
| 554 | case FIN_WAIT_1: |
| 555 | tcp_receive(pcb); |
| 556 | if (flags & TCP_FIN) { |
| 557 | if (flags & TCP_ACK && ackno == pcb->snd_nxt) { |
| 558 | LWIP_DEBUGF(TCP_DEBUG, |
| 559 | ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest)); |
| 560 | tcp_ack_now(pcb); |
| 561 | tcp_pcb_purge(pcb); |
| 562 | TCP_RMV(&tcp_active_pcbs, pcb); |
| 563 | pcb->state = TIME_WAIT; |
| 564 | TCP_REG(&tcp_tw_pcbs, pcb); |
| 565 | } else { |
| 566 | tcp_ack_now(pcb); |
| 567 | pcb->state = CLOSING; |
| 568 | } |
| 569 | } else if (flags & TCP_ACK && ackno == pcb->snd_nxt) { |
| 570 | pcb->state = FIN_WAIT_2; |
| 571 | } |
| 572 | break; |
| 573 | case FIN_WAIT_2: |
| 574 | tcp_receive(pcb); |
| 575 | if (flags & TCP_FIN) { |
| 576 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest)); |
| 577 | tcp_ack_now(pcb); |
| 578 | tcp_pcb_purge(pcb); |
| 579 | TCP_RMV(&tcp_active_pcbs, pcb); |
| 580 | pcb->state = TIME_WAIT; |
| 581 | TCP_REG(&tcp_tw_pcbs, pcb); |
| 582 | } |
| 583 | break; |
| 584 | case CLOSING: |
| 585 | tcp_receive(pcb); |
| 586 | if (flags & TCP_ACK && ackno == pcb->snd_nxt) { |
| 587 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest)); |
| 588 | tcp_ack_now(pcb); |
| 589 | tcp_pcb_purge(pcb); |
| 590 | TCP_RMV(&tcp_active_pcbs, pcb); |
| 591 | pcb->state = TIME_WAIT; |
| 592 | TCP_REG(&tcp_tw_pcbs, pcb); |
| 593 | } |
| 594 | break; |
| 595 | case LAST_ACK: |
| 596 | tcp_receive(pcb); |
| 597 | if (flags & TCP_ACK && ackno == pcb->snd_nxt) { |
| 598 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest)); |
| 599 | pcb->state = CLOSED; |
| 600 | recv_flags = TF_CLOSED; |
| 601 | } |
| 602 | break; |
| 603 | default: |
| 604 | break; |
| 605 | } |
| 606 | return ERR_OK; |
| 607 | } |
| 608 | |
| 609 | /* tcp_receive: |
| 610 | * |
| 611 | * Called by tcp_process. Checks if the given segment is an ACK for outstanding |
| 612 | * data, and if so frees the memory of the buffered data. Next, is places the |
| 613 | * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment |
| 614 | * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until |
| 615 | * i it has been removed from the buffer. |
| 616 | * |
| 617 | * If the incoming segment constitutes an ACK for a segment that was used for RTT |
| 618 | * estimation, the RTT is estimated here as well. |
| 619 | */ |
| 620 | |
| 621 | static void |
| 622 | tcp_receive(struct tcp_pcb *pcb) |
| 623 | { |
| 624 | struct tcp_seg *next; |
| 625 | #if TCP_QUEUE_OOSEQ |
| 626 | struct tcp_seg *prev, *cseg; |
| 627 | #endif |
| 628 | struct pbuf *p; |
| 629 | s32_t off; |
| 630 | s16_t m; |
| 631 | u32_t right_wnd_edge; |
| 632 | u16_t new_tot_len; |
| 633 | |
| 634 | |
| 635 | if (flags & TCP_ACK) { |
| 636 | right_wnd_edge = pcb->snd_wnd + pcb->snd_wl1; |
| 637 | |
| 638 | /* Update window. */ |
| 639 | if (TCP_SEQ_LT(pcb->snd_wl1, seqno) || |
| 640 | (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) || |
| 641 | (pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) { |
| 642 | pcb->snd_wnd = tcphdr->wnd; |
| 643 | pcb->snd_wl1 = seqno; |
| 644 | pcb->snd_wl2 = ackno; |
| 645 | LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U32_F"\n", pcb->snd_wnd)); |
| 646 | #if TCP_WND_DEBUG |
| 647 | } else { |
| 648 | if (pcb->snd_wnd != tcphdr->wnd) { |
| 649 | LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: no window update lastack %"U32_F" snd_max %"U32_F" ackno %"U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n", |
| 650 | pcb->lastack, pcb->snd_max, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2)); |
| 651 | } |
| 652 | #endif /* TCP_WND_DEBUG */ |
| 653 | } |
| 654 | |
| 655 | |
| 656 | if (pcb->lastack == ackno) { |
| 657 | pcb->acked = 0; |
| 658 | |
| 659 | if (pcb->snd_wl1 + pcb->snd_wnd == right_wnd_edge){ |
| 660 | ++pcb->dupacks; |
| 661 | if (pcb->dupacks >= 3 && pcb->unacked != NULL) { |
| 662 | if (!(pcb->flags & TF_INFR)) { |
| 663 | /* This is fast retransmit. Retransmit the first unacked segment. */ |
| 664 | LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupacks %"U16_F" (%"U32_F"), fast retransmit %"U32_F"\n", |
| 665 | (u16_t)pcb->dupacks, pcb->lastack, |
| 666 | ntohl(pcb->unacked->tcphdr->seqno))); |
| 667 | tcp_rexmit(pcb); |
| 668 | /* Set ssthresh to max (FlightSize / 2, 2*SMSS) */ |
| 669 | /*pcb->ssthresh = LWIP_MAX((pcb->snd_max - |
| 670 | pcb->lastack) / 2, |
| 671 | 2 * pcb->mss);*/ |
| 672 | /* Set ssthresh to half of the minimum of the currenct cwnd and the advertised window */ |
| 673 | if(pcb->cwnd > pcb->snd_wnd) |
| 674 | pcb->ssthresh = pcb->snd_wnd / 2; |
| 675 | else |
| 676 | pcb->ssthresh = pcb->cwnd / 2; |
| 677 | |
| 678 | pcb->cwnd = pcb->ssthresh + 3 * pcb->mss; |
| 679 | pcb->flags |= TF_INFR; |
| 680 | } else { |
| 681 | /* Inflate the congestion window, but not if it means that |
| 682 | the value overflows. */ |
| 683 | if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) { |
| 684 | pcb->cwnd += pcb->mss; |
| 685 | } |
| 686 | } |
| 687 | } |
| 688 | } else { |
| 689 | LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupack averted %"U32_F" %"U32_F"\n", |
| 690 | pcb->snd_wl1 + pcb->snd_wnd, right_wnd_edge)); |
| 691 | } |
| 692 | } else |
| 693 | /*if (TCP_SEQ_LT(pcb->lastack, ackno) && |
| 694 | TCP_SEQ_LEQ(ackno, pcb->snd_max)) { */ |
| 695 | if(TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_max)){ |
| 696 | /* We come here when the ACK acknowledges new data. */ |
| 697 | |
| 698 | /* Reset the "IN Fast Retransmit" flag, since we are no longer |
| 699 | in fast retransmit. Also reset the congestion window to the |
| 700 | slow start threshold. */ |
| 701 | if (pcb->flags & TF_INFR) { |
| 702 | pcb->flags &= ~TF_INFR; |
| 703 | pcb->cwnd = pcb->ssthresh; |
| 704 | } |
| 705 | |
| 706 | /* Reset the number of retransmissions. */ |
| 707 | pcb->nrtx = 0; |
| 708 | |
| 709 | /* Reset the retransmission time-out. */ |
| 710 | pcb->rto = (pcb->sa >> 3) + pcb->sv; |
| 711 | |
| 712 | /* Update the send buffer space. */ |
| 713 | pcb->acked = ackno - pcb->lastack; |
| 714 | |
| 715 | pcb->snd_buf += pcb->acked; |
| 716 | |
| 717 | /* Reset the fast retransmit variables. */ |
| 718 | pcb->dupacks = 0; |
| 719 | pcb->lastack = ackno; |
| 720 | |
| 721 | /* Update the congestion control variables (cwnd and |
| 722 | ssthresh). */ |
| 723 | if (pcb->state >= ESTABLISHED) { |
| 724 | if (pcb->cwnd < pcb->ssthresh) { |
| 725 | if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) { |
| 726 | pcb->cwnd += pcb->mss; |
| 727 | } |
| 728 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd)); |
| 729 | } else { |
| 730 | u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd); |
| 731 | if (new_cwnd > pcb->cwnd) { |
| 732 | pcb->cwnd = new_cwnd; |
| 733 | } |
| 734 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd)); |
| 735 | } |
| 736 | } |
| 737 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n", |
| 738 | ackno, |
| 739 | pcb->unacked != NULL? |
| 740 | ntohl(pcb->unacked->tcphdr->seqno): 0, |
| 741 | pcb->unacked != NULL? |
| 742 | ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0)); |
| 743 | |
| 744 | /* Remove segment from the unacknowledged list if the incoming |
| 745 | ACK acknowlegdes them. */ |
| 746 | while (pcb->unacked != NULL && |
| 747 | TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) + |
| 748 | TCP_TCPLEN(pcb->unacked), ackno)) { |
| 749 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n", |
| 750 | ntohl(pcb->unacked->tcphdr->seqno), |
| 751 | ntohl(pcb->unacked->tcphdr->seqno) + |
| 752 | TCP_TCPLEN(pcb->unacked))); |
| 753 | |
| 754 | next = pcb->unacked; |
| 755 | pcb->unacked = pcb->unacked->next; |
| 756 | |
| 757 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen)); |
| 758 | pcb->snd_queuelen -= pbuf_clen(next->p); |
| 759 | tcp_seg_free(next); |
| 760 | |
| 761 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen)); |
| 762 | if (pcb->snd_queuelen != 0) { |
| 763 | LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL || |
| 764 | pcb->unsent != NULL); |
| 765 | } |
| 766 | } |
| 767 | pcb->polltmr = 0; |
| 768 | } |
| 769 | |
| 770 | /* We go through the ->unsent list to see if any of the segments |
| 771 | on the list are acknowledged by the ACK. This may seem |
| 772 | strange since an "unsent" segment shouldn't be acked. The |
| 773 | rationale is that lwIP puts all outstanding segments on the |
| 774 | ->unsent list after a retransmission, so these segments may |
| 775 | in fact have been sent once. */ |
| 776 | while (pcb->unsent != NULL && |
| 777 | /*TCP_SEQ_LEQ(ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent), ackno) && |
| 778 | TCP_SEQ_LEQ(ackno, pcb->snd_max)*/ |
| 779 | TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent), pcb->snd_max) |
| 780 | ) { |
| 781 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n", |
| 782 | ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) + |
| 783 | TCP_TCPLEN(pcb->unsent))); |
| 784 | |
| 785 | next = pcb->unsent; |
| 786 | pcb->unsent = pcb->unsent->next; |
| 787 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen)); |
| 788 | pcb->snd_queuelen -= pbuf_clen(next->p); |
| 789 | tcp_seg_free(next); |
| 790 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen)); |
| 791 | if (pcb->snd_queuelen != 0) { |
| 792 | LWIP_ASSERT("tcp_receive: valid queue length", |
| 793 | pcb->unacked != NULL || pcb->unsent != NULL); |
| 794 | } |
| 795 | |
| 796 | if (pcb->unsent != NULL) { |
| 797 | pcb->snd_nxt = htonl(pcb->unsent->tcphdr->seqno); |
| 798 | } |
| 799 | } |
| 800 | /* End of ACK for new data processing. */ |
| 801 | |
| 802 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n", |
| 803 | pcb->rttest, pcb->rtseq, ackno)); |
| 804 | |
| 805 | /* RTT estimation calculations. This is done by checking if the |
| 806 | incoming segment acknowledges the segment we use to take a |
| 807 | round-trip time measurement. */ |
| 808 | if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) { |
| 809 | m = tcp_ticks - pcb->rttest; |
| 810 | |
| 811 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n", |
| 812 | m, m * TCP_SLOW_INTERVAL)); |
| 813 | |
| 814 | /* This is taken directly from VJs original code in his paper */ |
| 815 | m = m - (pcb->sa >> 3); |
| 816 | pcb->sa += m; |
| 817 | if (m < 0) { |
| 818 | m = -m; |
| 819 | } |
| 820 | m = m - (pcb->sv >> 2); |
| 821 | pcb->sv += m; |
| 822 | pcb->rto = (pcb->sa >> 3) + pcb->sv; |
| 823 | |
| 824 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" miliseconds)\n", |
| 825 | pcb->rto, pcb->rto * TCP_SLOW_INTERVAL)); |
| 826 | |
| 827 | pcb->rttest = 0; |
| 828 | } |
| 829 | } |
| 830 | |
| 831 | /* If the incoming segment contains data, we must process it |
| 832 | further. */ |
| 833 | if (tcplen > 0) { |
| 834 | /* This code basically does three things: |
| 835 | |
| 836 | +) If the incoming segment contains data that is the next |
| 837 | in-sequence data, this data is passed to the application. This |
| 838 | might involve trimming the first edge of the data. The rcv_nxt |
| 839 | variable and the advertised window are adjusted. |
| 840 | |
| 841 | +) If the incoming segment has data that is above the next |
| 842 | sequence number expected (->rcv_nxt), the segment is placed on |
| 843 | the ->ooseq queue. This is done by finding the appropriate |
| 844 | place in the ->ooseq queue (which is ordered by sequence |
| 845 | number) and trim the segment in both ends if needed. An |
| 846 | immediate ACK is sent to indicate that we received an |
| 847 | out-of-sequence segment. |
| 848 | |
| 849 | +) Finally, we check if the first segment on the ->ooseq queue |
| 850 | now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If |
| 851 | rcv_nxt > ooseq->seqno, we must trim the first edge of the |
| 852 | segment on ->ooseq before we adjust rcv_nxt. The data in the |
| 853 | segments that are now on sequence are chained onto the |
| 854 | incoming segment so that we only need to call the application |
| 855 | once. |
| 856 | */ |
| 857 | |
| 858 | /* First, we check if we must trim the first edge. We have to do |
| 859 | this if the sequence number of the incoming segment is less |
| 860 | than rcv_nxt, and the sequence number plus the length of the |
| 861 | segment is larger than rcv_nxt. */ |
| 862 | /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){ |
| 863 | if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/ |
| 864 | if(TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno+1, seqno+tcplen-1)){ |
| 865 | /* Trimming the first edge is done by pushing the payload |
| 866 | pointer in the pbuf downwards. This is somewhat tricky since |
| 867 | we do not want to discard the full contents of the pbuf up to |
| 868 | the new starting point of the data since we have to keep the |
| 869 | TCP header which is present in the first pbuf in the chain. |
| 870 | |
| 871 | What is done is really quite a nasty hack: the first pbuf in |
| 872 | the pbuf chain is pointed to by inseg.p. Since we need to be |
| 873 | able to deallocate the whole pbuf, we cannot change this |
| 874 | inseg.p pointer to point to any of the later pbufs in the |
| 875 | chain. Instead, we point the ->payload pointer in the first |
| 876 | pbuf to data in one of the later pbufs. We also set the |
| 877 | inseg.data pointer to point to the right place. This way, the |
| 878 | ->p pointer will still point to the first pbuf, but the |
| 879 | ->p->payload pointer will point to data in another pbuf. |
| 880 | |
| 881 | After we are done with adjusting the pbuf pointers we must |
| 882 | adjust the ->data pointer in the seg and the segment |
| 883 | length.*/ |
| 884 | |
| 885 | off = pcb->rcv_nxt - seqno; |
| 886 | p = inseg.p; |
| 887 | if (inseg.p->len < off) { |
| 888 | new_tot_len = inseg.p->tot_len - off; |
| 889 | while (p->len < off) { |
| 890 | off -= p->len; |
| 891 | /* KJM following line changed (with addition of new_tot_len var) |
| 892 | to fix bug #9076 |
| 893 | inseg.p->tot_len -= p->len; */ |
| 894 | p->tot_len = new_tot_len; |
| 895 | p->len = 0; |
| 896 | p = p->next; |
| 897 | } |
| 898 | pbuf_header(p, -off); |
| 899 | } else { |
| 900 | pbuf_header(inseg.p, -off); |
| 901 | } |
| 902 | /* KJM following line changed to use p->payload rather than inseg->p->payload |
| 903 | to fix bug #9076 */ |
| 904 | inseg.dataptr = p->payload; |
| 905 | inseg.len -= pcb->rcv_nxt - seqno; |
| 906 | inseg.tcphdr->seqno = seqno = pcb->rcv_nxt; |
| 907 | } |
| 908 | else{ |
| 909 | if(TCP_SEQ_LT(seqno, pcb->rcv_nxt)){ |
| 910 | /* the whole segment is < rcv_nxt */ |
| 911 | /* must be a duplicate of a packet that has already been correctly handled */ |
| 912 | |
| 913 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno)); |
| 914 | tcp_ack_now(pcb); |
| 915 | } |
| 916 | } |
| 917 | |
| 918 | /* The sequence number must be within the window (above rcv_nxt |
| 919 | and below rcv_nxt + rcv_wnd) in order to be further |
| 920 | processed. */ |
| 921 | /*if (TCP_SEQ_GEQ(seqno, pcb->rcv_nxt) && |
| 922 | TCP_SEQ_LT(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/ |
| 923 | if(TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd - 1)){ |
| 924 | if (pcb->rcv_nxt == seqno) { |
| 925 | /* The incoming segment is the next in sequence. We check if |
| 926 | we have to trim the end of the segment and update rcv_nxt |
| 927 | and pass the data to the application. */ |
| 928 | #if TCP_QUEUE_OOSEQ |
| 929 | if (pcb->ooseq != NULL && |
| 930 | TCP_SEQ_LEQ(pcb->ooseq->tcphdr->seqno, seqno + inseg.len)) { |
| 931 | /* We have to trim the second edge of the incoming |
| 932 | segment. */ |
| 933 | inseg.len = pcb->ooseq->tcphdr->seqno - seqno; |
| 934 | pbuf_realloc(inseg.p, inseg.len); |
| 935 | } |
| 936 | #endif /* TCP_QUEUE_OOSEQ */ |
| 937 | |
| 938 | tcplen = TCP_TCPLEN(&inseg); |
| 939 | |
| 940 | /* First received FIN will be ACKed +1, on any successive (duplicate) |
| 941 | * FINs we are already in CLOSE_WAIT and have already done +1. |
| 942 | */ |
| 943 | if (pcb->state != CLOSE_WAIT) { |
| 944 | pcb->rcv_nxt += tcplen; |
| 945 | } |
| 946 | |
| 947 | /* Update the receiver's (our) window. */ |
| 948 | if (pcb->rcv_wnd < tcplen) { |
| 949 | pcb->rcv_wnd = 0; |
| 950 | } else { |
| 951 | pcb->rcv_wnd -= tcplen; |
| 952 | } |
| 953 | |
| 954 | /* If there is data in the segment, we make preparations to |
| 955 | pass this up to the application. The ->recv_data variable |
| 956 | is used for holding the pbuf that goes to the |
| 957 | application. The code for reassembling out-of-sequence data |
| 958 | chains its data on this pbuf as well. |
| 959 | |
| 960 | If the segment was a FIN, we set the TF_GOT_FIN flag that will |
| 961 | be used to indicate to the application that the remote side has |
| 962 | closed its end of the connection. */ |
| 963 | if (inseg.p->tot_len > 0) { |
| 964 | recv_data = inseg.p; |
| 965 | /* Since this pbuf now is the responsibility of the |
| 966 | application, we delete our reference to it so that we won't |
| 967 | (mistakingly) deallocate it. */ |
| 968 | inseg.p = NULL; |
| 969 | } |
| 970 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) { |
| 971 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n")); |
| 972 | recv_flags = TF_GOT_FIN; |
| 973 | } |
| 974 | |
| 975 | #if TCP_QUEUE_OOSEQ |
| 976 | /* We now check if we have segments on the ->ooseq queue that |
| 977 | is now in sequence. */ |
| 978 | while (pcb->ooseq != NULL && |
| 979 | pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) { |
| 980 | |
| 981 | cseg = pcb->ooseq; |
| 982 | seqno = pcb->ooseq->tcphdr->seqno; |
| 983 | |
| 984 | pcb->rcv_nxt += TCP_TCPLEN(cseg); |
| 985 | if (pcb->rcv_wnd < TCP_TCPLEN(cseg)) { |
| 986 | pcb->rcv_wnd = 0; |
| 987 | } else { |
| 988 | pcb->rcv_wnd -= TCP_TCPLEN(cseg); |
| 989 | } |
| 990 | if (cseg->p->tot_len > 0) { |
| 991 | /* Chain this pbuf onto the pbuf that we will pass to |
| 992 | the application. */ |
| 993 | if (recv_data) { |
| 994 | pbuf_cat(recv_data, cseg->p); |
| 995 | } else { |
| 996 | recv_data = cseg->p; |
| 997 | } |
| 998 | cseg->p = NULL; |
| 999 | } |
| 1000 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) { |
| 1001 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n")); |
| 1002 | recv_flags = TF_GOT_FIN; |
| 1003 | } |
| 1004 | |
| 1005 | |
| 1006 | pcb->ooseq = cseg->next; |
| 1007 | tcp_seg_free(cseg); |
| 1008 | } |
| 1009 | #endif /* TCP_QUEUE_OOSEQ */ |
| 1010 | |
| 1011 | |
| 1012 | /* Acknowledge the segment(s). */ |
| 1013 | tcp_ack(pcb); |
| 1014 | |
| 1015 | } else { |
| 1016 | /* We get here if the incoming segment is out-of-sequence. */ |
| 1017 | tcp_ack_now(pcb); |
| 1018 | #if TCP_QUEUE_OOSEQ |
| 1019 | /* We queue the segment on the ->ooseq queue. */ |
| 1020 | if (pcb->ooseq == NULL) { |
| 1021 | pcb->ooseq = tcp_seg_copy(&inseg); |
| 1022 | } else { |
| 1023 | /* If the queue is not empty, we walk through the queue and |
| 1024 | try to find a place where the sequence number of the |
| 1025 | incoming segment is between the sequence numbers of the |
| 1026 | previous and the next segment on the ->ooseq queue. That is |
| 1027 | the place where we put the incoming segment. If needed, we |
| 1028 | trim the second edges of the previous and the incoming |
| 1029 | segment so that it will fit into the sequence. |
| 1030 | |
| 1031 | If the incoming segment has the same sequence number as a |
| 1032 | segment on the ->ooseq queue, we discard the segment that |
| 1033 | contains less data. */ |
| 1034 | |
| 1035 | prev = NULL; |
| 1036 | for(next = pcb->ooseq; next != NULL; next = next->next) { |
| 1037 | if (seqno == next->tcphdr->seqno) { |
| 1038 | /* The sequence number of the incoming segment is the |
| 1039 | same as the sequence number of the segment on |
| 1040 | ->ooseq. We check the lengths to see which one to |
| 1041 | discard. */ |
| 1042 | if (inseg.len > next->len) { |
| 1043 | /* The incoming segment is larger than the old |
| 1044 | segment. We replace the old segment with the new |
| 1045 | one. */ |
| 1046 | cseg = tcp_seg_copy(&inseg); |
| 1047 | if (cseg != NULL) { |
| 1048 | cseg->next = next->next; |
| 1049 | if (prev != NULL) { |
| 1050 | prev->next = cseg; |
| 1051 | } else { |
| 1052 | pcb->ooseq = cseg; |
| 1053 | } |
| 1054 | } |
| 1055 | break; |
| 1056 | } else { |
| 1057 | /* Either the lenghts are the same or the incoming |
| 1058 | segment was smaller than the old one; in either |
| 1059 | case, we ditch the incoming segment. */ |
| 1060 | break; |
| 1061 | } |
| 1062 | } else { |
| 1063 | if (prev == NULL) { |
| 1064 | if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) { |
| 1065 | /* The sequence number of the incoming segment is lower |
| 1066 | than the sequence number of the first segment on the |
| 1067 | queue. We put the incoming segment first on the |
| 1068 | queue. */ |
| 1069 | |
| 1070 | if (TCP_SEQ_GT(seqno + inseg.len, next->tcphdr->seqno)) { |
| 1071 | /* We need to trim the incoming segment. */ |
| 1072 | inseg.len = next->tcphdr->seqno - seqno; |
| 1073 | pbuf_realloc(inseg.p, inseg.len); |
| 1074 | } |
| 1075 | cseg = tcp_seg_copy(&inseg); |
| 1076 | if (cseg != NULL) { |
| 1077 | cseg->next = next; |
| 1078 | pcb->ooseq = cseg; |
| 1079 | } |
| 1080 | break; |
| 1081 | } |
| 1082 | } else |
| 1083 | /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) && |
| 1084 | TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/ |
| 1085 | if(TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)){ |
| 1086 | /* The sequence number of the incoming segment is in |
| 1087 | between the sequence numbers of the previous and |
| 1088 | the next segment on ->ooseq. We trim and insert the |
| 1089 | incoming segment and trim the previous segment, if |
| 1090 | needed. */ |
| 1091 | if (TCP_SEQ_GT(seqno + inseg.len, next->tcphdr->seqno)) { |
| 1092 | /* We need to trim the incoming segment. */ |
| 1093 | inseg.len = next->tcphdr->seqno - seqno; |
| 1094 | pbuf_realloc(inseg.p, inseg.len); |
| 1095 | } |
| 1096 | |
| 1097 | cseg = tcp_seg_copy(&inseg); |
| 1098 | if (cseg != NULL) { |
| 1099 | cseg->next = next; |
| 1100 | prev->next = cseg; |
| 1101 | if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) { |
| 1102 | /* We need to trim the prev segment. */ |
| 1103 | prev->len = seqno - prev->tcphdr->seqno; |
| 1104 | pbuf_realloc(prev->p, prev->len); |
| 1105 | } |
| 1106 | } |
| 1107 | break; |
| 1108 | } |
| 1109 | /* If the "next" segment is the last segment on the |
| 1110 | ooseq queue, we add the incoming segment to the end |
| 1111 | of the list. */ |
| 1112 | if (next->next == NULL && |
| 1113 | TCP_SEQ_GT(seqno, next->tcphdr->seqno)) { |
| 1114 | next->next = tcp_seg_copy(&inseg); |
| 1115 | if (next->next != NULL) { |
| 1116 | if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) { |
| 1117 | /* We need to trim the last segment. */ |
| 1118 | next->len = seqno - next->tcphdr->seqno; |
| 1119 | pbuf_realloc(next->p, next->len); |
| 1120 | } |
| 1121 | } |
| 1122 | break; |
| 1123 | } |
| 1124 | } |
| 1125 | prev = next; |
| 1126 | } |
| 1127 | } |
| 1128 | #endif /* TCP_QUEUE_OOSEQ */ |
| 1129 | |
| 1130 | } |
| 1131 | } else { |
| 1132 | /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) || |
| 1133 | TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/ |
| 1134 | if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){ |
| 1135 | tcp_ack_now(pcb); |
| 1136 | } |
| 1137 | } |
| 1138 | } else { |
| 1139 | /* Segments with length 0 is taken care of here. Segments that |
| 1140 | fall out of the window are ACKed. */ |
| 1141 | /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) || |
| 1142 | TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/ |
| 1143 | if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){ |
| 1144 | tcp_ack_now(pcb); |
| 1145 | } |
| 1146 | } |
| 1147 | } |
| 1148 | |
| 1149 | /* |
| 1150 | * tcp_parseopt: |
| 1151 | * |
| 1152 | * Parses the options contained in the incoming segment. (Code taken |
| 1153 | * from uIP with only small changes.) |
| 1154 | * |
| 1155 | */ |
| 1156 | |
| 1157 | static void |
| 1158 | tcp_parseopt(struct tcp_pcb *pcb) |
| 1159 | { |
| 1160 | u8_t c; |
| 1161 | u8_t *opts, opt; |
| 1162 | u16_t mss; |
| 1163 | |
| 1164 | opts = (u8_t *)tcphdr + TCP_HLEN; |
| 1165 | |
| 1166 | /* Parse the TCP MSS option, if present. */ |
| 1167 | if(TCPH_HDRLEN(tcphdr) > 0x5) { |
| 1168 | for(c = 0; c < (TCPH_HDRLEN(tcphdr) - 5) << 2 ;) { |
| 1169 | opt = opts[c]; |
| 1170 | if (opt == 0x00) { |
| 1171 | /* End of options. */ |
| 1172 | break; |
| 1173 | } else if (opt == 0x01) { |
| 1174 | ++c; |
| 1175 | /* NOP option. */ |
| 1176 | } else if (opt == 0x02 && |
| 1177 | opts[c + 1] == 0x04) { |
| 1178 | /* An MSS option with the right option length. */ |
| 1179 | mss = (opts[c + 2] << 8) | opts[c + 3]; |
| 1180 | pcb->mss = mss > TCP_MSS? TCP_MSS: mss; |
| 1181 | |
| 1182 | /* And we are done processing options. */ |
| 1183 | break; |
| 1184 | } else { |
| 1185 | if (opts[c + 1] == 0) { |
| 1186 | /* If the length field is zero, the options are malformed |
| 1187 | and we don't process them further. */ |
| 1188 | break; |
| 1189 | } |
| 1190 | /* All other options have a length field, so that we easily |
| 1191 | can skip past them. */ |
| 1192 | c += opts[c + 1]; |
| 1193 | } |
| 1194 | } |
| 1195 | } |
| 1196 | } |
| 1197 | #endif /* LWIP_TCP */ |
| 1198 | |
| 1199 | |