Travis Geiselbrecht | 1d0df69 | 2008-09-01 02:26:09 -0700 | [diff] [blame^] | 1 | /** |
| 2 | * @file |
| 3 | * |
| 4 | * Transmission Control Protocol, outgoing traffic |
| 5 | * |
| 6 | * The output functions of TCP. |
| 7 | * |
| 8 | */ |
| 9 | |
| 10 | /* |
| 11 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science. |
| 12 | * All rights reserved. |
| 13 | * |
| 14 | * Redistribution and use in source and binary forms, with or without modification, |
| 15 | * are permitted provided that the following conditions are met: |
| 16 | * |
| 17 | * 1. Redistributions of source code must retain the above copyright notice, |
| 18 | * this list of conditions and the following disclaimer. |
| 19 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 20 | * this list of conditions and the following disclaimer in the documentation |
| 21 | * and/or other materials provided with the distribution. |
| 22 | * 3. The name of the author may not be used to endorse or promote products |
| 23 | * derived from this software without specific prior written permission. |
| 24 | * |
| 25 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 26 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 27 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT |
| 28 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 29 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 30 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 31 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 32 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
| 33 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY |
| 34 | * OF SUCH DAMAGE. |
| 35 | * |
| 36 | * This file is part of the lwIP TCP/IP stack. |
| 37 | * |
| 38 | * Author: Adam Dunkels <adam@sics.se> |
| 39 | * |
| 40 | */ |
| 41 | |
| 42 | #include <string.h> |
| 43 | |
| 44 | #include "lwip/def.h" |
| 45 | #include "lwip/opt.h" |
| 46 | #include "lwip/mem.h" |
| 47 | #include "lwip/memp.h" |
| 48 | #include "lwip/sys.h" |
| 49 | #include "lwip/ip_addr.h" |
| 50 | #include "lwip/netif.h" |
| 51 | #include "lwip/inet.h" |
| 52 | #include "lwip/tcp.h" |
| 53 | #include "lwip/stats.h" |
| 54 | |
| 55 | #if LWIP_TCP |
| 56 | |
| 57 | /* Forward declarations.*/ |
| 58 | static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb); |
| 59 | |
| 60 | err_t |
| 61 | tcp_send_ctrl(struct tcp_pcb *pcb, u8_t flags) |
| 62 | { |
| 63 | /* no data, no length, flags, copy=1, no optdata, no optdatalen */ |
| 64 | return tcp_enqueue(pcb, NULL, 0, flags, 1, NULL, 0); |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Write data for sending (but does not send it immediately). |
| 69 | * |
| 70 | * It waits in the expectation of more data being sent soon (as |
| 71 | * it can send them more efficiently by combining them together). |
| 72 | * To prompt the system to send data now, call tcp_output() after |
| 73 | * calling tcp_write(). |
| 74 | * |
| 75 | * @arg pcb Protocol control block of the TCP connection to enqueue data for. |
| 76 | * |
| 77 | * @see tcp_write() |
| 78 | */ |
| 79 | |
| 80 | err_t |
| 81 | tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t copy) |
| 82 | { |
| 83 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, arg=%p, len=%"U16_F", copy=%"U16_F")\n", (void *)pcb, |
| 84 | arg, len, (u16_t)copy)); |
| 85 | /* connection is in valid state for data transmission? */ |
| 86 | if (pcb->state == ESTABLISHED || |
| 87 | pcb->state == CLOSE_WAIT || |
| 88 | pcb->state == SYN_SENT || |
| 89 | pcb->state == SYN_RCVD) { |
| 90 | if (len > 0) { |
| 91 | return tcp_enqueue(pcb, (void *)arg, len, 0, copy, NULL, 0); |
| 92 | } |
| 93 | return ERR_OK; |
| 94 | } else { |
| 95 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_STATE | 3, ("tcp_write() called in invalid state\n")); |
| 96 | return ERR_CONN; |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * Enqueue either data or TCP options (but not both) for tranmission |
| 102 | * |
| 103 | * |
| 104 | * |
| 105 | * @arg pcb Protocol control block for the TCP connection to enqueue data for. |
| 106 | * @arg arg Pointer to the data to be enqueued for sending. |
| 107 | * @arg len Data length in bytes |
| 108 | * @arg flags |
| 109 | * @arg copy 1 if data must be copied, 0 if data is non-volatile and can be |
| 110 | * referenced. |
| 111 | * @arg optdata |
| 112 | * @arg optlen |
| 113 | */ |
| 114 | err_t |
| 115 | tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len, |
| 116 | u8_t flags, u8_t copy, |
| 117 | u8_t *optdata, u8_t optlen) |
| 118 | { |
| 119 | struct pbuf *p; |
| 120 | struct tcp_seg *seg, *useg, *queue; |
| 121 | u32_t left, seqno; |
| 122 | u16_t seglen; |
| 123 | void *ptr; |
| 124 | u8_t queuelen; |
| 125 | |
| 126 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_enqueue(pcb=%p, arg=%p, len=%"U16_F", flags=%"X16_F", copy=%"U16_F")\n", |
| 127 | (void *)pcb, arg, len, (u16_t)flags, (u16_t)copy)); |
| 128 | LWIP_ASSERT("tcp_enqueue: len == 0 || optlen == 0 (programmer violates API)", |
| 129 | len == 0 || optlen == 0); |
| 130 | LWIP_ASSERT("tcp_enqueue: arg == NULL || optdata == NULL (programmer violates API)", |
| 131 | arg == NULL || optdata == NULL); |
| 132 | /* fail on too much data */ |
| 133 | if (len > pcb->snd_buf) { |
| 134 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n", len, pcb->snd_buf)); |
| 135 | return ERR_MEM; |
| 136 | } |
| 137 | left = len; |
| 138 | ptr = arg; |
| 139 | |
| 140 | /* seqno will be the sequence number of the first segment enqueued |
| 141 | * by the call to this function. */ |
| 142 | seqno = pcb->snd_lbb; |
| 143 | |
| 144 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen)); |
| 145 | |
| 146 | /* If total number of pbufs on the unsent/unacked queues exceeds the |
| 147 | * configured maximum, return an error */ |
| 148 | queuelen = pcb->snd_queuelen; |
| 149 | if (queuelen >= TCP_SND_QUEUELEN) { |
| 150 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue: too long queue %"U16_F" (max %"U16_F")\n", queuelen, TCP_SND_QUEUELEN)); |
| 151 | TCP_STATS_INC(tcp.memerr); |
| 152 | return ERR_MEM; |
| 153 | } |
| 154 | if (queuelen != 0) { |
| 155 | LWIP_ASSERT("tcp_enqueue: pbufs on queue => at least one queue non-empty", |
| 156 | pcb->unacked != NULL || pcb->unsent != NULL); |
| 157 | } else { |
| 158 | LWIP_ASSERT("tcp_enqueue: no pbufs on queue => both queues empty", |
| 159 | pcb->unacked == NULL && pcb->unsent == NULL); |
| 160 | } |
| 161 | |
| 162 | /* First, break up the data into segments and tuck them together in |
| 163 | * the local "queue" variable. */ |
| 164 | useg = queue = seg = NULL; |
| 165 | seglen = 0; |
| 166 | while (queue == NULL || left > 0) { |
| 167 | |
| 168 | /* The segment length should be the MSS if the data to be enqueued |
| 169 | * is larger than the MSS. */ |
| 170 | seglen = left > pcb->mss? pcb->mss: left; |
| 171 | |
| 172 | /* Allocate memory for tcp_seg, and fill in fields. */ |
| 173 | seg = memp_malloc(MEMP_TCP_SEG); |
| 174 | if (seg == NULL) { |
| 175 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for tcp_seg\n")); |
| 176 | goto memerr; |
| 177 | } |
| 178 | seg->next = NULL; |
| 179 | seg->p = NULL; |
| 180 | |
| 181 | /* first segment of to-be-queued data? */ |
| 182 | if (queue == NULL) { |
| 183 | queue = seg; |
| 184 | } |
| 185 | /* subsequent segments of to-be-queued data */ |
| 186 | else { |
| 187 | /* Attach the segment to the end of the queued segments */ |
| 188 | LWIP_ASSERT("useg != NULL", useg != NULL); |
| 189 | useg->next = seg; |
| 190 | } |
| 191 | /* remember last segment of to-be-queued data for next iteration */ |
| 192 | useg = seg; |
| 193 | |
| 194 | /* If copy is set, memory should be allocated |
| 195 | * and data copied into pbuf, otherwise data comes from |
| 196 | * ROM or other static memory, and need not be copied. If |
| 197 | * optdata is != NULL, we have options instead of data. */ |
| 198 | |
| 199 | /* options? */ |
| 200 | if (optdata != NULL) { |
| 201 | if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) { |
| 202 | goto memerr; |
| 203 | } |
| 204 | ++queuelen; |
| 205 | seg->dataptr = seg->p->payload; |
| 206 | } |
| 207 | /* copy from volatile memory? */ |
| 208 | else if (copy) { |
| 209 | if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_RAM)) == NULL) { |
| 210 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue : could not allocate memory for pbuf copy size %"U16_F"\n", seglen)); |
| 211 | goto memerr; |
| 212 | } |
| 213 | ++queuelen; |
| 214 | if (arg != NULL) { |
| 215 | memcpy(seg->p->payload, ptr, seglen); |
| 216 | } |
| 217 | seg->dataptr = seg->p->payload; |
| 218 | } |
| 219 | /* do not copy data */ |
| 220 | else { |
| 221 | /* First, allocate a pbuf for holding the data. |
| 222 | * since the referenced data is available at least until it is sent out on the |
| 223 | * link (as it has to be ACKed by the remote party) we can safely use PBUF_ROM |
| 224 | * instead of PBUF_REF here. |
| 225 | */ |
| 226 | if ((p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) { |
| 227 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for zero-copy pbuf\n")); |
| 228 | goto memerr; |
| 229 | } |
| 230 | ++queuelen; |
| 231 | /* reference the non-volatile payload data */ |
| 232 | p->payload = ptr; |
| 233 | seg->dataptr = ptr; |
| 234 | |
| 235 | /* Second, allocate a pbuf for the headers. */ |
| 236 | if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_RAM)) == NULL) { |
| 237 | /* If allocation fails, we have to deallocate the data pbuf as |
| 238 | * well. */ |
| 239 | pbuf_free(p); |
| 240 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for header pbuf\n")); |
| 241 | goto memerr; |
| 242 | } |
| 243 | ++queuelen; |
| 244 | |
| 245 | /* Concatenate the headers and data pbufs together. */ |
| 246 | pbuf_cat(seg->p/*header*/, p/*data*/); |
| 247 | p = NULL; |
| 248 | } |
| 249 | |
| 250 | /* Now that there are more segments queued, we check again if the |
| 251 | length of the queue exceeds the configured maximum. */ |
| 252 | if (queuelen > TCP_SND_QUEUELEN) { |
| 253 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN)); |
| 254 | goto memerr; |
| 255 | } |
| 256 | |
| 257 | seg->len = seglen; |
| 258 | |
| 259 | /* build TCP header */ |
| 260 | if (pbuf_header(seg->p, TCP_HLEN)) { |
| 261 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: no room for TCP header in pbuf.\n")); |
| 262 | TCP_STATS_INC(tcp.err); |
| 263 | goto memerr; |
| 264 | } |
| 265 | seg->tcphdr = seg->p->payload; |
| 266 | seg->tcphdr->src = htons(pcb->local_port); |
| 267 | seg->tcphdr->dest = htons(pcb->remote_port); |
| 268 | seg->tcphdr->seqno = htonl(seqno); |
| 269 | seg->tcphdr->urgp = 0; |
| 270 | TCPH_FLAGS_SET(seg->tcphdr, flags); |
| 271 | /* don't fill in tcphdr->ackno and tcphdr->wnd until later */ |
| 272 | |
| 273 | /* Copy the options into the header, if they are present. */ |
| 274 | if (optdata == NULL) { |
| 275 | TCPH_HDRLEN_SET(seg->tcphdr, 5); |
| 276 | } |
| 277 | else { |
| 278 | TCPH_HDRLEN_SET(seg->tcphdr, (5 + optlen / 4)); |
| 279 | /* Copy options into data portion of segment. |
| 280 | Options can thus only be sent in non data carrying |
| 281 | segments such as SYN|ACK. */ |
| 282 | memcpy(seg->dataptr, optdata, optlen); |
| 283 | } |
| 284 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_TRACE, ("tcp_enqueue: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n", |
| 285 | ntohl(seg->tcphdr->seqno), |
| 286 | ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg), |
| 287 | (u16_t)flags)); |
| 288 | |
| 289 | left -= seglen; |
| 290 | seqno += seglen; |
| 291 | ptr = (void *)((u8_t *)ptr + seglen); |
| 292 | } |
| 293 | |
| 294 | /* Now that the data to be enqueued has been broken up into TCP |
| 295 | segments in the queue variable, we add them to the end of the |
| 296 | pcb->unsent queue. */ |
| 297 | if (pcb->unsent == NULL) { |
| 298 | useg = NULL; |
| 299 | } |
| 300 | else { |
| 301 | for (useg = pcb->unsent; useg->next != NULL; useg = useg->next); |
| 302 | } |
| 303 | /* { useg is last segment on the unsent queue, NULL if list is empty } */ |
| 304 | |
| 305 | /* If there is room in the last pbuf on the unsent queue, |
| 306 | chain the first pbuf on the queue together with that. */ |
| 307 | if (useg != NULL && |
| 308 | TCP_TCPLEN(useg) != 0 && |
| 309 | !(TCPH_FLAGS(useg->tcphdr) & (TCP_SYN | TCP_FIN)) && |
| 310 | !(flags & (TCP_SYN | TCP_FIN)) && |
| 311 | /* fit within max seg size */ |
| 312 | useg->len + queue->len <= pcb->mss) { |
| 313 | /* Remove TCP header from first segment of our to-be-queued list */ |
| 314 | pbuf_header(queue->p, -TCP_HLEN); |
| 315 | pbuf_cat(useg->p, queue->p); |
| 316 | useg->len += queue->len; |
| 317 | useg->next = queue->next; |
| 318 | |
| 319 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_TRACE | DBG_STATE, ("tcp_enqueue: chaining segments, new len %"U16_F"\n", useg->len)); |
| 320 | if (seg == queue) { |
| 321 | seg = NULL; |
| 322 | } |
| 323 | memp_free(MEMP_TCP_SEG, queue); |
| 324 | } |
| 325 | else { |
| 326 | /* empty list */ |
| 327 | if (useg == NULL) { |
| 328 | /* initialize list with this segment */ |
| 329 | pcb->unsent = queue; |
| 330 | } |
| 331 | /* enqueue segment */ |
| 332 | else { |
| 333 | useg->next = queue; |
| 334 | } |
| 335 | } |
| 336 | if ((flags & TCP_SYN) || (flags & TCP_FIN)) { |
| 337 | ++len; |
| 338 | } |
| 339 | pcb->snd_lbb += len; |
| 340 | |
| 341 | pcb->snd_buf -= len; |
| 342 | |
| 343 | /* update number of segments on the queues */ |
| 344 | pcb->snd_queuelen = queuelen; |
| 345 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: %"S16_F" (after enqueued)\n", pcb->snd_queuelen)); |
| 346 | if (pcb->snd_queuelen != 0) { |
| 347 | LWIP_ASSERT("tcp_enqueue: valid queue length", |
| 348 | pcb->unacked != NULL || pcb->unsent != NULL); |
| 349 | } |
| 350 | |
| 351 | /* Set the PSH flag in the last segment that we enqueued, but only |
| 352 | if the segment has data (indicated by seglen > 0). */ |
| 353 | if (seg != NULL && seglen > 0 && seg->tcphdr != NULL) { |
| 354 | TCPH_SET_FLAG(seg->tcphdr, TCP_PSH); |
| 355 | } |
| 356 | |
| 357 | return ERR_OK; |
| 358 | memerr: |
| 359 | TCP_STATS_INC(tcp.memerr); |
| 360 | |
| 361 | if (queue != NULL) { |
| 362 | tcp_segs_free(queue); |
| 363 | } |
| 364 | if (pcb->snd_queuelen != 0) { |
| 365 | LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL || |
| 366 | pcb->unsent != NULL); |
| 367 | } |
| 368 | LWIP_DEBUGF(TCP_QLEN_DEBUG | DBG_STATE, ("tcp_enqueue: %"S16_F" (with mem err)\n", pcb->snd_queuelen)); |
| 369 | return ERR_MEM; |
| 370 | } |
| 371 | |
| 372 | /* find out what we can send and send it */ |
| 373 | err_t |
| 374 | tcp_output(struct tcp_pcb *pcb) |
| 375 | { |
| 376 | struct pbuf *p; |
| 377 | struct tcp_hdr *tcphdr; |
| 378 | struct tcp_seg *seg, *useg; |
| 379 | u32_t wnd; |
| 380 | #if TCP_CWND_DEBUG |
| 381 | s16_t i = 0; |
| 382 | #endif /* TCP_CWND_DEBUG */ |
| 383 | |
| 384 | /* First, check if we are invoked by the TCP input processing |
| 385 | code. If so, we do not output anything. Instead, we rely on the |
| 386 | input processing code to call us when input processing is done |
| 387 | with. */ |
| 388 | if (tcp_input_pcb == pcb) { |
| 389 | return ERR_OK; |
| 390 | } |
| 391 | |
| 392 | wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd); |
| 393 | |
| 394 | seg = pcb->unsent; |
| 395 | |
| 396 | /* useg should point to last segment on unacked queue */ |
| 397 | useg = pcb->unacked; |
| 398 | if (useg != NULL) { |
| 399 | for (; useg->next != NULL; useg = useg->next); |
| 400 | } |
| 401 | |
| 402 | /* If the TF_ACK_NOW flag is set and no data will be sent (either |
| 403 | * because the ->unsent queue is empty or because the window does |
| 404 | * not allow it), construct an empty ACK segment and send it. |
| 405 | * |
| 406 | * If data is to be sent, we will just piggyback the ACK (see below). |
| 407 | */ |
| 408 | if (pcb->flags & TF_ACK_NOW && |
| 409 | (seg == NULL || |
| 410 | ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) { |
| 411 | p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM); |
| 412 | if (p == NULL) { |
| 413 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n")); |
| 414 | return ERR_BUF; |
| 415 | } |
| 416 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt)); |
| 417 | /* remove ACK flags from the PCB, as we send an empty ACK now */ |
| 418 | pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW); |
| 419 | |
| 420 | tcphdr = p->payload; |
| 421 | tcphdr->src = htons(pcb->local_port); |
| 422 | tcphdr->dest = htons(pcb->remote_port); |
| 423 | tcphdr->seqno = htonl(pcb->snd_nxt); |
| 424 | tcphdr->ackno = htonl(pcb->rcv_nxt); |
| 425 | TCPH_FLAGS_SET(tcphdr, TCP_ACK); |
| 426 | tcphdr->wnd = htons(pcb->rcv_wnd); |
| 427 | tcphdr->urgp = 0; |
| 428 | TCPH_HDRLEN_SET(tcphdr, 5); |
| 429 | |
| 430 | tcphdr->chksum = 0; |
| 431 | #if CHECKSUM_GEN_TCP |
| 432 | tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip), |
| 433 | IP_PROTO_TCP, p->tot_len); |
| 434 | #endif |
| 435 | ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, |
| 436 | IP_PROTO_TCP); |
| 437 | pbuf_free(p); |
| 438 | |
| 439 | return ERR_OK; |
| 440 | } |
| 441 | |
| 442 | #if TCP_OUTPUT_DEBUG |
| 443 | if (seg == NULL) { |
| 444 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n", (void*)pcb->unsent)); |
| 445 | } |
| 446 | #endif /* TCP_OUTPUT_DEBUG */ |
| 447 | #if TCP_CWND_DEBUG |
| 448 | if (seg == NULL) { |
| 449 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U32_F", cwnd %"U16_F", wnd %"U32_F", seg == NULL, ack %"U32_F"\n", |
| 450 | pcb->snd_wnd, pcb->cwnd, wnd, |
| 451 | pcb->lastack)); |
| 452 | } else { |
| 453 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U32_F", cwnd %"U16_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n", |
| 454 | pcb->snd_wnd, pcb->cwnd, wnd, |
| 455 | ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len, |
| 456 | ntohl(seg->tcphdr->seqno), pcb->lastack)); |
| 457 | } |
| 458 | #endif /* TCP_CWND_DEBUG */ |
| 459 | /* data available and window allows it to be sent? */ |
| 460 | while (seg != NULL && |
| 461 | ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) { |
| 462 | #if TCP_CWND_DEBUG |
| 463 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U32_F", cwnd %"U16_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n", |
| 464 | pcb->snd_wnd, pcb->cwnd, wnd, |
| 465 | ntohl(seg->tcphdr->seqno) + seg->len - |
| 466 | pcb->lastack, |
| 467 | ntohl(seg->tcphdr->seqno), pcb->lastack, i)); |
| 468 | ++i; |
| 469 | #endif /* TCP_CWND_DEBUG */ |
| 470 | |
| 471 | pcb->unsent = seg->next; |
| 472 | |
| 473 | if (pcb->state != SYN_SENT) { |
| 474 | TCPH_SET_FLAG(seg->tcphdr, TCP_ACK); |
| 475 | pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW); |
| 476 | } |
| 477 | |
| 478 | tcp_output_segment(seg, pcb); |
| 479 | pcb->snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg); |
| 480 | if (TCP_SEQ_LT(pcb->snd_max, pcb->snd_nxt)) { |
| 481 | pcb->snd_max = pcb->snd_nxt; |
| 482 | } |
| 483 | /* put segment on unacknowledged list if length > 0 */ |
| 484 | if (TCP_TCPLEN(seg) > 0) { |
| 485 | seg->next = NULL; |
| 486 | /* unacked list is empty? */ |
| 487 | if (pcb->unacked == NULL) { |
| 488 | pcb->unacked = seg; |
| 489 | useg = seg; |
| 490 | /* unacked list is not empty? */ |
| 491 | } else { |
| 492 | /* In the case of fast retransmit, the packet should not go to the tail |
| 493 | * of the unacked queue, but rather at the head. We need to check for |
| 494 | * this case. -STJ Jul 27, 2004 */ |
| 495 | if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))){ |
| 496 | /* add segment to head of unacked list */ |
| 497 | seg->next = pcb->unacked; |
| 498 | pcb->unacked = seg; |
| 499 | } else { |
| 500 | /* add segment to tail of unacked list */ |
| 501 | useg->next = seg; |
| 502 | useg = useg->next; |
| 503 | } |
| 504 | } |
| 505 | /* do not queue empty segments on the unacked list */ |
| 506 | } else { |
| 507 | tcp_seg_free(seg); |
| 508 | } |
| 509 | seg = pcb->unsent; |
| 510 | } |
| 511 | return ERR_OK; |
| 512 | } |
| 513 | |
| 514 | /** |
| 515 | * Actually send a TCP segment over IP |
| 516 | */ |
| 517 | static void |
| 518 | tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb) |
| 519 | { |
| 520 | u16_t len; |
| 521 | struct netif *netif; |
| 522 | |
| 523 | /* The TCP header has already been constructed, but the ackno and |
| 524 | wnd fields remain. */ |
| 525 | seg->tcphdr->ackno = htonl(pcb->rcv_nxt); |
| 526 | |
| 527 | /* silly window avoidance */ |
| 528 | if (pcb->rcv_wnd < pcb->mss) { |
| 529 | seg->tcphdr->wnd = 0; |
| 530 | } else { |
| 531 | /* advertise our receive window size in this TCP segment */ |
| 532 | seg->tcphdr->wnd = htons(pcb->rcv_wnd); |
| 533 | } |
| 534 | |
| 535 | /* If we don't have a local IP address, we get one by |
| 536 | calling ip_route(). */ |
| 537 | if (ip_addr_isany(&(pcb->local_ip))) { |
| 538 | netif = ip_route(&(pcb->remote_ip)); |
| 539 | if (netif == NULL) { |
| 540 | return; |
| 541 | } |
| 542 | ip_addr_set(&(pcb->local_ip), &(netif->ip_addr)); |
| 543 | } |
| 544 | |
| 545 | pcb->rtime = 0; |
| 546 | |
| 547 | if (pcb->rttest == 0) { |
| 548 | pcb->rttest = tcp_ticks; |
| 549 | pcb->rtseq = ntohl(seg->tcphdr->seqno); |
| 550 | |
| 551 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq)); |
| 552 | } |
| 553 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n", |
| 554 | htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) + |
| 555 | seg->len)); |
| 556 | |
| 557 | len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload); |
| 558 | |
| 559 | seg->p->len -= len; |
| 560 | seg->p->tot_len -= len; |
| 561 | |
| 562 | seg->p->payload = seg->tcphdr; |
| 563 | |
| 564 | seg->tcphdr->chksum = 0; |
| 565 | #if CHECKSUM_GEN_TCP |
| 566 | seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, |
| 567 | &(pcb->local_ip), |
| 568 | &(pcb->remote_ip), |
| 569 | IP_PROTO_TCP, seg->p->tot_len); |
| 570 | #endif |
| 571 | TCP_STATS_INC(tcp.xmit); |
| 572 | |
| 573 | ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, |
| 574 | IP_PROTO_TCP); |
| 575 | } |
| 576 | |
| 577 | void |
| 578 | tcp_rst(u32_t seqno, u32_t ackno, |
| 579 | struct ip_addr *local_ip, struct ip_addr *remote_ip, |
| 580 | u16_t local_port, u16_t remote_port) |
| 581 | { |
| 582 | struct pbuf *p; |
| 583 | struct tcp_hdr *tcphdr; |
| 584 | p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM); |
| 585 | if (p == NULL) { |
| 586 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n")); |
| 587 | return; |
| 588 | } |
| 589 | |
| 590 | tcphdr = p->payload; |
| 591 | tcphdr->src = htons(local_port); |
| 592 | tcphdr->dest = htons(remote_port); |
| 593 | tcphdr->seqno = htonl(seqno); |
| 594 | tcphdr->ackno = htonl(ackno); |
| 595 | TCPH_FLAGS_SET(tcphdr, TCP_RST | TCP_ACK); |
| 596 | tcphdr->wnd = htons(TCP_WND); |
| 597 | tcphdr->urgp = 0; |
| 598 | TCPH_HDRLEN_SET(tcphdr, 5); |
| 599 | |
| 600 | tcphdr->chksum = 0; |
| 601 | #if CHECKSUM_GEN_TCP |
| 602 | tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip, |
| 603 | IP_PROTO_TCP, p->tot_len); |
| 604 | #endif |
| 605 | TCP_STATS_INC(tcp.xmit); |
| 606 | /* Send output with hardcoded TTL since we have no access to the pcb */ |
| 607 | ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP); |
| 608 | pbuf_free(p); |
| 609 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno)); |
| 610 | } |
| 611 | |
| 612 | /* requeue all unacked segments for retransmission */ |
| 613 | void |
| 614 | tcp_rexmit_rto(struct tcp_pcb *pcb) |
| 615 | { |
| 616 | struct tcp_seg *seg; |
| 617 | |
| 618 | if (pcb->unacked == NULL) { |
| 619 | return; |
| 620 | } |
| 621 | |
| 622 | /* Move all unacked segments to the head of the unsent queue */ |
| 623 | for (seg = pcb->unacked; seg->next != NULL; seg = seg->next); |
| 624 | /* concatenate unsent queue after unacked queue */ |
| 625 | seg->next = pcb->unsent; |
| 626 | /* unsent queue is the concatenated queue (of unacked, unsent) */ |
| 627 | pcb->unsent = pcb->unacked; |
| 628 | /* unacked queue is now empty */ |
| 629 | pcb->unacked = NULL; |
| 630 | |
| 631 | pcb->snd_nxt = ntohl(pcb->unsent->tcphdr->seqno); |
| 632 | /* increment number of retransmissions */ |
| 633 | ++pcb->nrtx; |
| 634 | |
| 635 | /* Don't take any RTT measurements after retransmitting. */ |
| 636 | pcb->rttest = 0; |
| 637 | |
| 638 | /* Do the actual retransmission */ |
| 639 | tcp_output(pcb); |
| 640 | } |
| 641 | |
| 642 | void |
| 643 | tcp_rexmit(struct tcp_pcb *pcb) |
| 644 | { |
| 645 | struct tcp_seg *seg; |
| 646 | |
| 647 | if (pcb->unacked == NULL) { |
| 648 | return; |
| 649 | } |
| 650 | |
| 651 | /* Move the first unacked segment to the unsent queue */ |
| 652 | seg = pcb->unacked->next; |
| 653 | pcb->unacked->next = pcb->unsent; |
| 654 | pcb->unsent = pcb->unacked; |
| 655 | pcb->unacked = seg; |
| 656 | |
| 657 | pcb->snd_nxt = ntohl(pcb->unsent->tcphdr->seqno); |
| 658 | |
| 659 | ++pcb->nrtx; |
| 660 | |
| 661 | /* Don't take any rtt measurements after retransmitting. */ |
| 662 | pcb->rttest = 0; |
| 663 | |
| 664 | /* Do the actual retransmission. */ |
| 665 | tcp_output(pcb); |
| 666 | |
| 667 | } |
| 668 | |
| 669 | |
| 670 | void |
| 671 | tcp_keepalive(struct tcp_pcb *pcb) |
| 672 | { |
| 673 | struct pbuf *p; |
| 674 | struct tcp_hdr *tcphdr; |
| 675 | |
| 676 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n", |
| 677 | ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip), |
| 678 | ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip))); |
| 679 | |
| 680 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt %"U16_F"\n", tcp_ticks, pcb->tmr, pcb->keep_cnt)); |
| 681 | |
| 682 | p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM); |
| 683 | |
| 684 | if(p == NULL) { |
| 685 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: could not allocate memory for pbuf\n")); |
| 686 | return; |
| 687 | } |
| 688 | |
| 689 | tcphdr = p->payload; |
| 690 | tcphdr->src = htons(pcb->local_port); |
| 691 | tcphdr->dest = htons(pcb->remote_port); |
| 692 | tcphdr->seqno = htonl(pcb->snd_nxt - 1); |
| 693 | tcphdr->ackno = htonl(pcb->rcv_nxt); |
| 694 | tcphdr->wnd = htons(pcb->rcv_wnd); |
| 695 | tcphdr->urgp = 0; |
| 696 | TCPH_HDRLEN_SET(tcphdr, 5); |
| 697 | |
| 698 | tcphdr->chksum = 0; |
| 699 | #if CHECKSUM_GEN_TCP |
| 700 | tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip, IP_PROTO_TCP, p->tot_len); |
| 701 | #endif |
| 702 | TCP_STATS_INC(tcp.xmit); |
| 703 | |
| 704 | /* Send output to IP */ |
| 705 | ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP); |
| 706 | |
| 707 | pbuf_free(p); |
| 708 | |
| 709 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n", pcb->snd_nxt - 1, pcb->rcv_nxt)); |
| 710 | } |
| 711 | |
| 712 | #endif /* LWIP_TCP */ |
| 713 | |
| 714 | |
| 715 | |
| 716 | |
| 717 | |
| 718 | |
| 719 | |
| 720 | |
| 721 | |