source: UsbWattMeter/trunk/lwip-1.4.1/src/core/tcp_out.c@ 164

Last change on this file since 164 was 164, checked in by coas-nagasima, 6 years ago

TOPPERS/ECNLサンプルアプリ「USB充電器電力計」を追加

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1/**
2 * @file
3 * Transmission Control Protocol, outgoing traffic
4 *
5 * The output functions of TCP.
6 *
7 */
8
9/*
10 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
11 * All rights reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without modification,
14 * are permitted provided that the following conditions are met:
15 *
16 * 1. Redistributions of source code must retain the above copyright notice,
17 * this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright notice,
19 * this list of conditions and the following disclaimer in the documentation
20 * and/or other materials provided with the distribution.
21 * 3. The name of the author may not be used to endorse or promote products
22 * derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
25 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
26 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
27 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
28 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
29 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
32 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
33 * OF SUCH DAMAGE.
34 *
35 * This file is part of the lwIP TCP/IP stack.
36 *
37 * Author: Adam Dunkels <adam@sics.se>
38 *
39 */
40
41#include "lwip/opt.h"
42
43#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
44
45#include "lwip/tcp_impl.h"
46#include "lwip/def.h"
47#include "lwip/mem.h"
48#include "lwip/memp.h"
49#include "lwip/ip_addr.h"
50#include "lwip/netif.h"
51#include "lwip/inet_chksum.h"
52#include "lwip/stats.h"
53#include "lwip/snmp.h"
54#if LWIP_TCP_TIMESTAMPS
55#include "lwip/sys.h"
56#endif
57
58#include <string.h>
59
60/* Define some copy-macros for checksum-on-copy so that the code looks
61 nicer by preventing too many ifdef's. */
62#if TCP_CHECKSUM_ON_COPY
63#define TCP_DATA_COPY(dst, src, len, seg) do { \
64 tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
65 len, &seg->chksum, &seg->chksum_swapped); \
66 seg->flags |= TF_SEG_DATA_CHECKSUMMED; } while(0)
67#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
68 tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
69#else /* TCP_CHECKSUM_ON_COPY*/
70#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
71#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
72#endif /* TCP_CHECKSUM_ON_COPY*/
73
74/** Define this to 1 for an extra check that the output checksum is valid
75 * (usefule when the checksum is generated by the application, not the stack) */
76#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
77#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
78#endif
79
80/* Forward declarations.*/
81static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb);
82
83/** Allocate a pbuf and create a tcphdr at p->payload, used for output
84 * functions other than the default tcp_output -> tcp_output_segment
85 * (e.g. tcp_send_empty_ack, etc.)
86 *
87 * @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
88 * @param optlen length of header-options
89 * @param datalen length of tcp data to reserve in pbuf
90 * @param seqno_be seqno in network byte order (big-endian)
91 * @return pbuf with p->payload being the tcp_hdr
92 */
93static struct pbuf *
94tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
95 u32_t seqno_be /* already in network byte order */)
96{
97 struct tcp_hdr *tcphdr;
98 struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
99 if (p != NULL) {
100 LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
101 (p->len >= TCP_HLEN + optlen));
102 tcphdr = (struct tcp_hdr *)p->payload;
103 tcphdr->src = htons(pcb->local_port);
104 tcphdr->dest = htons(pcb->remote_port);
105 tcphdr->seqno = seqno_be;
106 tcphdr->ackno = htonl(pcb->rcv_nxt);
107 TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
108 tcphdr->wnd = htons(pcb->rcv_ann_wnd);
109 tcphdr->chksum = 0;
110 tcphdr->urgp = 0;
111
112 /* If we're sending a packet, update the announced right window edge */
113 pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
114 }
115 return p;
116}
117
118/**
119 * Called by tcp_close() to send a segment including FIN flag but not data.
120 *
121 * @param pcb the tcp_pcb over which to send a segment
122 * @return ERR_OK if sent, another err_t otherwise
123 */
124err_t
125tcp_send_fin(struct tcp_pcb *pcb)
126{
127 /* first, try to add the fin to the last unsent segment */
128 if (pcb->unsent != NULL) {
129 struct tcp_seg *last_unsent;
130 for (last_unsent = pcb->unsent; last_unsent->next != NULL;
131 last_unsent = last_unsent->next);
132
133 if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
134 /* no SYN/FIN/RST flag in the header, we can add the FIN flag */
135 TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
136 pcb->flags |= TF_FIN;
137 return ERR_OK;
138 }
139 }
140 /* no data, no length, flags, copy=1, no optdata */
141 return tcp_enqueue_flags(pcb, TCP_FIN);
142}
143
144/**
145 * Create a TCP segment with prefilled header.
146 *
147 * Called by tcp_write and tcp_enqueue_flags.
148 *
149 * @param pcb Protocol control block for the TCP connection.
150 * @param p pbuf that is used to hold the TCP header.
151 * @param flags TCP flags for header.
152 * @param seqno TCP sequence number of this packet
153 * @param optflags options to include in TCP header
154 * @return a new tcp_seg pointing to p, or NULL.
155 * The TCP header is filled in except ackno and wnd.
156 * p is freed on failure.
157 */
158static struct tcp_seg *
159tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno, u8_t optflags)
160{
161 struct tcp_seg *seg;
162 u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
163
164 if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
165 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n"));
166 pbuf_free(p);
167 return NULL;
168 }
169 seg->flags = optflags;
170 seg->next = NULL;
171 seg->p = p;
172 seg->len = p->tot_len - optlen;
173#if TCP_OVERSIZE_DBGCHECK
174 seg->oversize_left = 0;
175#endif /* TCP_OVERSIZE_DBGCHECK */
176#if TCP_CHECKSUM_ON_COPY
177 seg->chksum = 0;
178 seg->chksum_swapped = 0;
179 /* check optflags */
180 LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
181 (optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
182#endif /* TCP_CHECKSUM_ON_COPY */
183
184 /* build TCP header */
185 if (pbuf_header(p, TCP_HLEN)) {
186 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
187 TCP_STATS_INC(tcp.err);
188 tcp_seg_free(seg);
189 return NULL;
190 }
191 seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
192 seg->tcphdr->src = htons(pcb->local_port);
193 seg->tcphdr->dest = htons(pcb->remote_port);
194 seg->tcphdr->seqno = htonl(seqno);
195 /* ackno is set in tcp_output */
196 TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
197 /* wnd and chksum are set in tcp_output */
198 seg->tcphdr->urgp = 0;
199 return seg;
200}
201
202/**
203 * Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
204 *
205 * This function is like pbuf_alloc(layer, length, PBUF_RAM) except
206 * there may be extra bytes available at the end.
207 *
208 * @param layer flag to define header size.
209 * @param length size of the pbuf's payload.
210 * @param max_length maximum usable size of payload+oversize.
211 * @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
212 * @param pcb The TCP connection that willo enqueue the pbuf.
213 * @param apiflags API flags given to tcp_write.
214 * @param first_seg true when this pbuf will be used in the first enqueued segment.
215 * @param
216 */
217#if TCP_OVERSIZE
218static struct pbuf *
219tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
220 u16_t *oversize, struct tcp_pcb *pcb, u8_t apiflags,
221 u8_t first_seg)
222{
223 struct pbuf *p;
224 u16_t alloc = length;
225
226#if LWIP_NETIF_TX_SINGLE_PBUF
227 LWIP_UNUSED_ARG(max_length);
228 LWIP_UNUSED_ARG(pcb);
229 LWIP_UNUSED_ARG(apiflags);
230 LWIP_UNUSED_ARG(first_seg);
231 /* always create MSS-sized pbufs */
232 alloc = max_length;
233#else /* LWIP_NETIF_TX_SINGLE_PBUF */
234 if (length < max_length) {
235 /* Should we allocate an oversized pbuf, or just the minimum
236 * length required? If tcp_write is going to be called again
237 * before this segment is transmitted, we want the oversized
238 * buffer. If the segment will be transmitted immediately, we can
239 * save memory by allocating only length. We use a simple
240 * heuristic based on the following information:
241 *
242 * Did the user set TCP_WRITE_FLAG_MORE?
243 *
244 * Will the Nagle algorithm defer transmission of this segment?
245 */
246 if ((apiflags & TCP_WRITE_FLAG_MORE) ||
247 (!(pcb->flags & TF_NODELAY) &&
248 (!first_seg ||
249 pcb->unsent != NULL ||
250 pcb->unacked != NULL))) {
251 alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
252 }
253 }
254#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
255 p = pbuf_alloc(layer, alloc, PBUF_RAM);
256 if (p == NULL) {
257 return NULL;
258 }
259 LWIP_ASSERT("need unchained pbuf", p->next == NULL);
260 *oversize = p->len - length;
261 /* trim p->len to the currently used size */
262 p->len = p->tot_len = length;
263 return p;
264}
265#else /* TCP_OVERSIZE */
266#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
267#endif /* TCP_OVERSIZE */
268
269#if TCP_CHECKSUM_ON_COPY
270/** Add a checksum of newly added data to the segment */
271static void
272tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
273 u8_t *seg_chksum_swapped)
274{
275 u32_t helper;
276 /* add chksum to old chksum and fold to u16_t */
277 helper = chksum + *seg_chksum;
278 chksum = FOLD_U32T(helper);
279 if ((len & 1) != 0) {
280 *seg_chksum_swapped = 1 - *seg_chksum_swapped;
281 chksum = SWAP_BYTES_IN_WORD(chksum);
282 }
283 *seg_chksum = chksum;
284}
285#endif /* TCP_CHECKSUM_ON_COPY */
286
287/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
288 *
289 * @param pcb the tcp pcb to check for
290 * @param len length of data to send (checked agains snd_buf)
291 * @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
292 */
293static err_t
294tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
295{
296 /* connection is in invalid state for data transmission? */
297 if ((pcb->state != ESTABLISHED) &&
298 (pcb->state != CLOSE_WAIT) &&
299 (pcb->state != SYN_SENT) &&
300 (pcb->state != SYN_RCVD)) {
301 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
302 return ERR_CONN;
303 } else if (len == 0) {
304 return ERR_OK;
305 }
306
307 /* fail on too much data */
308 if (len > pcb->snd_buf) {
309 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
310 len, pcb->snd_buf));
311 pcb->flags |= TF_NAGLEMEMERR;
312 return ERR_MEM;
313 }
314
315 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
316
317 /* If total number of pbufs on the unsent/unacked queues exceeds the
318 * configured maximum, return an error */
319 /* check for configured max queuelen and possible overflow */
320 if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
321 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
322 pcb->snd_queuelen, TCP_SND_QUEUELEN));
323 TCP_STATS_INC(tcp.memerr);
324 pcb->flags |= TF_NAGLEMEMERR;
325 return ERR_MEM;
326 }
327 if (pcb->snd_queuelen != 0) {
328 LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
329 pcb->unacked != NULL || pcb->unsent != NULL);
330 } else {
331 LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
332 pcb->unacked == NULL && pcb->unsent == NULL);
333 }
334 return ERR_OK;
335}
336
337/**
338 * Write data for sending (but does not send it immediately).
339 *
340 * It waits in the expectation of more data being sent soon (as
341 * it can send them more efficiently by combining them together).
342 * To prompt the system to send data now, call tcp_output() after
343 * calling tcp_write().
344 *
345 * @param pcb Protocol control block for the TCP connection to enqueue data for.
346 * @param arg Pointer to the data to be enqueued for sending.
347 * @param len Data length in bytes
348 * @param apiflags combination of following flags :
349 * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
350 * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
351 * @return ERR_OK if enqueued, another err_t on error
352 */
353err_t
354tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
355{
356 struct pbuf *concat_p = NULL;
357 struct tcp_seg *last_unsent = NULL, *seg = NULL, *prev_seg = NULL, *queue = NULL;
358 u16_t pos = 0; /* position in 'arg' data */
359 u16_t queuelen;
360 u8_t optlen = 0;
361 u8_t optflags = 0;
362#if TCP_OVERSIZE
363 u16_t oversize = 0;
364 u16_t oversize_used = 0;
365#endif /* TCP_OVERSIZE */
366#if TCP_CHECKSUM_ON_COPY
367 u16_t concat_chksum = 0;
368 u8_t concat_chksum_swapped = 0;
369 u16_t concat_chksummed = 0;
370#endif /* TCP_CHECKSUM_ON_COPY */
371 err_t err;
372 /* don't allocate segments bigger than half the maximum window we ever received */
373 u16_t mss_local = LWIP_MIN(pcb->mss, pcb->snd_wnd_max/2);
374
375#if LWIP_NETIF_TX_SINGLE_PBUF
376 /* Always copy to try to create single pbufs for TX */
377 apiflags |= TCP_WRITE_FLAG_COPY;
378#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
379
380 LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
381 (void *)pcb, arg, len, (u16_t)apiflags));
382 LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
383 arg != NULL, return ERR_ARG;);
384
385 err = tcp_write_checks(pcb, len);
386 if (err != ERR_OK) {
387 return err;
388 }
389 queuelen = pcb->snd_queuelen;
390
391#if LWIP_TCP_TIMESTAMPS
392 if ((pcb->flags & TF_TIMESTAMP)) {
393 optflags = TF_SEG_OPTS_TS;
394 optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
395 }
396#endif /* LWIP_TCP_TIMESTAMPS */
397
398
399 /*
400 * TCP segmentation is done in three phases with increasing complexity:
401 *
402 * 1. Copy data directly into an oversized pbuf.
403 * 2. Chain a new pbuf to the end of pcb->unsent.
404 * 3. Create new segments.
405 *
406 * We may run out of memory at any point. In that case we must
407 * return ERR_MEM and not change anything in pcb. Therefore, all
408 * changes are recorded in local variables and committed at the end
409 * of the function. Some pcb fields are maintained in local copies:
410 *
411 * queuelen = pcb->snd_queuelen
412 * oversize = pcb->unsent_oversize
413 *
414 * These variables are set consistently by the phases:
415 *
416 * seg points to the last segment tampered with.
417 *
418 * pos records progress as data is segmented.
419 */
420
421 /* Find the tail of the unsent queue. */
422 if (pcb->unsent != NULL) {
423 u16_t space;
424 u16_t unsent_optlen;
425
426 /* @todo: this could be sped up by keeping last_unsent in the pcb */
427 for (last_unsent = pcb->unsent; last_unsent->next != NULL;
428 last_unsent = last_unsent->next);
429
430 /* Usable space at the end of the last unsent segment */
431 unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
432 space = mss_local - (last_unsent->len + unsent_optlen);
433
434 /*
435 * Phase 1: Copy data directly into an oversized pbuf.
436 *
437 * The number of bytes copied is recorded in the oversize_used
438 * variable. The actual copying is done at the bottom of the
439 * function.
440 */
441#if TCP_OVERSIZE
442#if TCP_OVERSIZE_DBGCHECK
443 /* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
444 LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
445 pcb->unsent_oversize == last_unsent->oversize_left);
446#endif /* TCP_OVERSIZE_DBGCHECK */
447 oversize = pcb->unsent_oversize;
448 if (oversize > 0) {
449 LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
450 seg = last_unsent;
451 oversize_used = oversize < len ? oversize : len;
452 pos += oversize_used;
453 oversize -= oversize_used;
454 space -= oversize_used;
455 }
456 /* now we are either finished or oversize is zero */
457 LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) || (pos == len));
458#endif /* TCP_OVERSIZE */
459
460 /*
461 * Phase 2: Chain a new pbuf to the end of pcb->unsent.
462 *
463 * We don't extend segments containing SYN/FIN flags or options
464 * (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
465 * the end.
466 */
467 if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
468 u16_t seglen = space < len - pos ? space : len - pos;
469 seg = last_unsent;
470
471 /* Create a pbuf with a copy or reference to seglen bytes. We
472 * can use PBUF_RAW here since the data appears in the middle of
473 * a segment. A header will never be prepended. */
474 if (apiflags & TCP_WRITE_FLAG_COPY) {
475 /* Data is copied */
476 if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
477 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
478 ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
479 seglen));
480 goto memerr;
481 }
482#if TCP_OVERSIZE_DBGCHECK
483 last_unsent->oversize_left += oversize;
484#endif /* TCP_OVERSIZE_DBGCHECK */
485 TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
486#if TCP_CHECKSUM_ON_COPY
487 concat_chksummed += seglen;
488#endif /* TCP_CHECKSUM_ON_COPY */
489 } else {
490 /* Data is not copied */
491 if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
492 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
493 ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
494 goto memerr;
495 }
496#if TCP_CHECKSUM_ON_COPY
497 /* calculate the checksum of nocopy-data */
498 tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
499 &concat_chksum, &concat_chksum_swapped);
500 concat_chksummed += seglen;
501#endif /* TCP_CHECKSUM_ON_COPY */
502 /* reference the non-volatile payload data */
503 concat_p->payload = (u8_t*)arg + pos;
504 }
505
506 pos += seglen;
507 queuelen += pbuf_clen(concat_p);
508 }
509 } else {
510#if TCP_OVERSIZE
511 LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
512 pcb->unsent_oversize == 0);
513#endif /* TCP_OVERSIZE */
514 }
515
516 /*
517 * Phase 3: Create new segments.
518 *
519 * The new segments are chained together in the local 'queue'
520 * variable, ready to be appended to pcb->unsent.
521 */
522 while (pos < len) {
523 struct pbuf *p;
524 u16_t left = len - pos;
525 u16_t max_len = mss_local - optlen;
526 u16_t seglen = left > max_len ? max_len : left;
527#if TCP_CHECKSUM_ON_COPY
528 u16_t chksum = 0;
529 u8_t chksum_swapped = 0;
530#endif /* TCP_CHECKSUM_ON_COPY */
531
532 if (apiflags & TCP_WRITE_FLAG_COPY) {
533 /* If copy is set, memory should be allocated and data copied
534 * into pbuf */
535 if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
536 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
537 goto memerr;
538 }
539 LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
540 (p->len >= seglen));
541 TCP_DATA_COPY2((char *)p->payload + optlen, (u8_t*)arg + pos, seglen, &chksum, &chksum_swapped);
542 } else {
543 /* Copy is not set: First allocate a pbuf for holding the data.
544 * Since the referenced data is available at least until it is
545 * sent out on the link (as it has to be ACKed by the remote
546 * party) we can safely use PBUF_ROM instead of PBUF_REF here.
547 */
548 struct pbuf *p2;
549#if TCP_OVERSIZE
550 LWIP_ASSERT("oversize == 0", oversize == 0);
551#endif /* TCP_OVERSIZE */
552 if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
553 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
554 goto memerr;
555 }
556#if TCP_CHECKSUM_ON_COPY
557 /* calculate the checksum of nocopy-data */
558 chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
559#endif /* TCP_CHECKSUM_ON_COPY */
560 /* reference the non-volatile payload data */
561 p2->payload = (u8_t*)arg + pos;
562
563 /* Second, allocate a pbuf for the headers. */
564 if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
565 /* If allocation fails, we have to deallocate the data pbuf as
566 * well. */
567 pbuf_free(p2);
568 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for header pbuf\n"));
569 goto memerr;
570 }
571 /* Concatenate the headers and data pbufs together. */
572 pbuf_cat(p/*header*/, p2/*data*/);
573 }
574
575 queuelen += pbuf_clen(p);
576
577 /* Now that there are more segments queued, we check again if the
578 * length of the queue exceeds the configured maximum or
579 * overflows. */
580 if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
581 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
582 pbuf_free(p);
583 goto memerr;
584 }
585
586 if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
587 goto memerr;
588 }
589#if TCP_OVERSIZE_DBGCHECK
590 seg->oversize_left = oversize;
591#endif /* TCP_OVERSIZE_DBGCHECK */
592#if TCP_CHECKSUM_ON_COPY
593 seg->chksum = chksum;
594 seg->chksum_swapped = chksum_swapped;
595 seg->flags |= TF_SEG_DATA_CHECKSUMMED;
596#endif /* TCP_CHECKSUM_ON_COPY */
597
598 /* first segment of to-be-queued data? */
599 if (queue == NULL) {
600 queue = seg;
601 } else {
602 /* Attach the segment to the end of the queued segments */
603 LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
604 prev_seg->next = seg;
605 }
606 /* remember last segment of to-be-queued data for next iteration */
607 prev_seg = seg;
608
609 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
610 ntohl(seg->tcphdr->seqno),
611 ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
612
613 pos += seglen;
614 }
615
616 /*
617 * All three segmentation phases were successful. We can commit the
618 * transaction.
619 */
620
621 /*
622 * Phase 1: If data has been added to the preallocated tail of
623 * last_unsent, we update the length fields of the pbuf chain.
624 */
625#if TCP_OVERSIZE
626 if (oversize_used > 0) {
627 struct pbuf *p;
628 /* Bump tot_len of whole chain, len of tail */
629 for (p = last_unsent->p; p; p = p->next) {
630 p->tot_len += oversize_used;
631 if (p->next == NULL) {
632 TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
633 p->len += oversize_used;
634 }
635 }
636 last_unsent->len += oversize_used;
637#if TCP_OVERSIZE_DBGCHECK
638 LWIP_ASSERT("last_unsent->oversize_left >= oversize_used",
639 last_unsent->oversize_left >= oversize_used);
640 last_unsent->oversize_left -= oversize_used;
641#endif /* TCP_OVERSIZE_DBGCHECK */
642 }
643 pcb->unsent_oversize = oversize;
644#endif /* TCP_OVERSIZE */
645
646 /*
647 * Phase 2: concat_p can be concatenated onto last_unsent->p
648 */
649 if (concat_p != NULL) {
650 LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
651 (last_unsent != NULL));
652 pbuf_cat(last_unsent->p, concat_p);
653 last_unsent->len += concat_p->tot_len;
654#if TCP_CHECKSUM_ON_COPY
655 if (concat_chksummed) {
656 tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
657 &last_unsent->chksum_swapped);
658 last_unsent->flags |= TF_SEG_DATA_CHECKSUMMED;
659 }
660#endif /* TCP_CHECKSUM_ON_COPY */
661 }
662
663 /*
664 * Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
665 * is harmless
666 */
667 if (last_unsent == NULL) {
668 pcb->unsent = queue;
669 } else {
670 last_unsent->next = queue;
671 }
672
673 /*
674 * Finally update the pcb state.
675 */
676 pcb->snd_lbb += len;
677 pcb->snd_buf -= len;
678 pcb->snd_queuelen = queuelen;
679
680 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
681 pcb->snd_queuelen));
682 if (pcb->snd_queuelen != 0) {
683 LWIP_ASSERT("tcp_write: valid queue length",
684 pcb->unacked != NULL || pcb->unsent != NULL);
685 }
686
687 /* Set the PSH flag in the last segment that we enqueued. */
688 if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
689 TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
690 }
691
692 return ERR_OK;
693memerr:
694 pcb->flags |= TF_NAGLEMEMERR;
695 TCP_STATS_INC(tcp.memerr);
696
697 if (concat_p != NULL) {
698 pbuf_free(concat_p);
699 }
700 if (queue != NULL) {
701 tcp_segs_free(queue);
702 }
703 if (pcb->snd_queuelen != 0) {
704 LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL ||
705 pcb->unsent != NULL);
706 }
707 LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
708 return ERR_MEM;
709}
710
711/**
712 * Enqueue TCP options for transmission.
713 *
714 * Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
715 *
716 * @param pcb Protocol control block for the TCP connection.
717 * @param flags TCP header flags to set in the outgoing segment.
718 * @param optdata pointer to TCP options, or NULL.
719 * @param optlen length of TCP options in bytes.
720 */
721err_t
722tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
723{
724 struct pbuf *p;
725 struct tcp_seg *seg;
726 u8_t optflags = 0;
727 u8_t optlen = 0;
728
729 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
730
731 LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
732 (flags & (TCP_SYN | TCP_FIN)) != 0);
733
734 /* check for configured max queuelen and possible overflow */
735 if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
736 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
737 pcb->snd_queuelen, TCP_SND_QUEUELEN));
738 TCP_STATS_INC(tcp.memerr);
739 pcb->flags |= TF_NAGLEMEMERR;
740 return ERR_MEM;
741 }
742
743 if (flags & TCP_SYN) {
744 optflags = TF_SEG_OPTS_MSS;
745 }
746#if LWIP_TCP_TIMESTAMPS
747 if ((pcb->flags & TF_TIMESTAMP)) {
748 optflags |= TF_SEG_OPTS_TS;
749 }
750#endif /* LWIP_TCP_TIMESTAMPS */
751 optlen = LWIP_TCP_OPT_LENGTH(optflags);
752
753 /* tcp_enqueue_flags is always called with either SYN or FIN in flags.
754 * We need one available snd_buf byte to do that.
755 * This means we can't send FIN while snd_buf==0. A better fix would be to
756 * not include SYN and FIN sequence numbers in the snd_buf count. */
757 if (pcb->snd_buf == 0) {
758 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: no send buffer available\n"));
759 TCP_STATS_INC(tcp.memerr);
760 return ERR_MEM;
761 }
762
763 /* Allocate pbuf with room for TCP header + options */
764 if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
765 pcb->flags |= TF_NAGLEMEMERR;
766 TCP_STATS_INC(tcp.memerr);
767 return ERR_MEM;
768 }
769 LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
770 (p->len >= optlen));
771
772 /* Allocate memory for tcp_seg, and fill in fields. */
773 if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
774 pcb->flags |= TF_NAGLEMEMERR;
775 TCP_STATS_INC(tcp.memerr);
776 return ERR_MEM;
777 }
778 LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)seg->tcphdr % MEM_ALIGNMENT) == 0);
779 LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
780
781 LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE,
782 ("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
783 ntohl(seg->tcphdr->seqno),
784 ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
785 (u16_t)flags));
786
787 /* Now append seg to pcb->unsent queue */
788 if (pcb->unsent == NULL) {
789 pcb->unsent = seg;
790 } else {
791 struct tcp_seg *useg;
792 for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
793 useg->next = seg;
794 }
795#if TCP_OVERSIZE
796 /* The new unsent tail has no space */
797 pcb->unsent_oversize = 0;
798#endif /* TCP_OVERSIZE */
799
800 /* SYN and FIN bump the sequence number */
801 if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
802 pcb->snd_lbb++;
803 /* optlen does not influence snd_buf */
804 pcb->snd_buf--;
805 }
806 if (flags & TCP_FIN) {
807 pcb->flags |= TF_FIN;
808 }
809
810 /* update number of segments on the queues */
811 pcb->snd_queuelen += pbuf_clen(seg->p);
812 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
813 if (pcb->snd_queuelen != 0) {
814 LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
815 pcb->unacked != NULL || pcb->unsent != NULL);
816 }
817
818 return ERR_OK;
819}
820
821#if LWIP_TCP_TIMESTAMPS
822/* Build a timestamp option (12 bytes long) at the specified options pointer)
823 *
824 * @param pcb tcp_pcb
825 * @param opts option pointer where to store the timestamp option
826 */
827static void
828tcp_build_timestamp_option(struct tcp_pcb *pcb, u32_t *opts)
829{
830 /* Pad with two NOP options to make everything nicely aligned */
831 opts[0] = PP_HTONL(0x0101080A);
832 opts[1] = htonl(sys_now());
833 opts[2] = htonl(pcb->ts_recent);
834}
835#endif
836
837/** Send an ACK without data.
838 *
839 * @param pcb Protocol control block for the TCP connection to send the ACK
840 */
841err_t
842tcp_send_empty_ack(struct tcp_pcb *pcb)
843{
844 struct pbuf *p;
845 struct tcp_hdr *tcphdr;
846 u8_t optlen = 0;
847
848#if LWIP_TCP_TIMESTAMPS
849 if (pcb->flags & TF_TIMESTAMP) {
850 optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
851 }
852#endif
853
854 p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
855 if (p == NULL) {
856 LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
857 return ERR_BUF;
858 }
859 tcphdr = (struct tcp_hdr *)p->payload;
860 LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
861 ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
862 /* remove ACK flags from the PCB, as we send an empty ACK now */
863 pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
864
865 /* NB. MSS option is only sent on SYNs, so ignore it here */
866#if LWIP_TCP_TIMESTAMPS
867 pcb->ts_lastacksent = pcb->rcv_nxt;
868
869 if (pcb->flags & TF_TIMESTAMP) {
870 tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
871 }
872#endif
873
874#if CHECKSUM_GEN_TCP
875 tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
876 IP_PROTO_TCP, p->tot_len);
877#endif
878#if LWIP_NETIF_HWADDRHINT
879 ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
880 IP_PROTO_TCP, &(pcb->addr_hint));
881#else /* LWIP_NETIF_HWADDRHINT*/
882 ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
883 IP_PROTO_TCP);
884#endif /* LWIP_NETIF_HWADDRHINT*/
885 pbuf_free(p);
886
887 return ERR_OK;
888}
889
890/**
891 * Find out what we can send and send it
892 *
893 * @param pcb Protocol control block for the TCP connection to send data
894 * @return ERR_OK if data has been sent or nothing to send
895 * another err_t on error
896 */
897err_t
898tcp_output(struct tcp_pcb *pcb)
899{
900 struct tcp_seg *seg, *useg;
901 u32_t wnd, snd_nxt;
902#if TCP_CWND_DEBUG
903 s16_t i = 0;
904#endif /* TCP_CWND_DEBUG */
905
906 /* pcb->state LISTEN not allowed here */
907 LWIP_ASSERT("don't call tcp_output for listen-pcbs",
908 pcb->state != LISTEN);
909
910 /* First, check if we are invoked by the TCP input processing
911 code. If so, we do not output anything. Instead, we rely on the
912 input processing code to call us when input processing is done
913 with. */
914 if (tcp_input_pcb == pcb) {
915 return ERR_OK;
916 }
917
918 wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
919
920 seg = pcb->unsent;
921
922 /* If the TF_ACK_NOW flag is set and no data will be sent (either
923 * because the ->unsent queue is empty or because the window does
924 * not allow it), construct an empty ACK segment and send it.
925 *
926 * If data is to be sent, we will just piggyback the ACK (see below).
927 */
928 if (pcb->flags & TF_ACK_NOW &&
929 (seg == NULL ||
930 ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
931 return tcp_send_empty_ack(pcb);
932 }
933
934 /* useg should point to last segment on unacked queue */
935 useg = pcb->unacked;
936 if (useg != NULL) {
937 for (; useg->next != NULL; useg = useg->next);
938 }
939
940#if TCP_OUTPUT_DEBUG
941 if (seg == NULL) {
942 LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
943 (void*)pcb->unsent));
944 }
945#endif /* TCP_OUTPUT_DEBUG */
946#if TCP_CWND_DEBUG
947 if (seg == NULL) {
948 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
949 ", cwnd %"U16_F", wnd %"U32_F
950 ", seg == NULL, ack %"U32_F"\n",
951 pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
952 } else {
953 LWIP_DEBUGF(TCP_CWND_DEBUG,
954 ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
955 ", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
956 pcb->snd_wnd, pcb->cwnd, wnd,
957 ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
958 ntohl(seg->tcphdr->seqno), pcb->lastack));
959 }
960#endif /* TCP_CWND_DEBUG */
961 /* data available and window allows it to be sent? */
962 while (seg != NULL &&
963 ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
964 LWIP_ASSERT("RST not expected here!",
965 (TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
966 /* Stop sending if the nagle algorithm would prevent it
967 * Don't stop:
968 * - if tcp_write had a memory error before (prevent delayed ACK timeout) or
969 * - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
970 * either seg->next != NULL or pcb->unacked == NULL;
971 * RST is no sent using tcp_write/tcp_output.
972 */
973 if((tcp_do_output_nagle(pcb) == 0) &&
974 ((pcb->flags & (TF_NAGLEMEMERR | TF_FIN)) == 0)){
975 break;
976 }
977#if TCP_CWND_DEBUG
978 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n",
979 pcb->snd_wnd, pcb->cwnd, wnd,
980 ntohl(seg->tcphdr->seqno) + seg->len -
981 pcb->lastack,
982 ntohl(seg->tcphdr->seqno), pcb->lastack, i));
983 ++i;
984#endif /* TCP_CWND_DEBUG */
985
986 pcb->unsent = seg->next;
987
988 if (pcb->state != SYN_SENT) {
989 TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
990 pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
991 }
992
993 tcp_output_segment(seg, pcb);
994 snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
995 if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
996 pcb->snd_nxt = snd_nxt;
997 }
998 /* put segment on unacknowledged list if length > 0 */
999 if (TCP_TCPLEN(seg) > 0) {
1000 seg->next = NULL;
1001 /* unacked list is empty? */
1002 if (pcb->unacked == NULL) {
1003 pcb->unacked = seg;
1004 useg = seg;
1005 /* unacked list is not empty? */
1006 } else {
1007 /* In the case of fast retransmit, the packet should not go to the tail
1008 * of the unacked queue, but rather somewhere before it. We need to check for
1009 * this case. -STJ Jul 27, 2004 */
1010 if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
1011 /* add segment to before tail of unacked list, keeping the list sorted */
1012 struct tcp_seg **cur_seg = &(pcb->unacked);
1013 while (*cur_seg &&
1014 TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
1015 cur_seg = &((*cur_seg)->next );
1016 }
1017 seg->next = (*cur_seg);
1018 (*cur_seg) = seg;
1019 } else {
1020 /* add segment to tail of unacked list */
1021 useg->next = seg;
1022 useg = useg->next;
1023 }
1024 }
1025 /* do not queue empty segments on the unacked list */
1026 } else {
1027 tcp_seg_free(seg);
1028 }
1029 seg = pcb->unsent;
1030 }
1031#if TCP_OVERSIZE
1032 if (pcb->unsent == NULL) {
1033 /* last unsent has been removed, reset unsent_oversize */
1034 pcb->unsent_oversize = 0;
1035 }
1036#endif /* TCP_OVERSIZE */
1037
1038 pcb->flags &= ~TF_NAGLEMEMERR;
1039 return ERR_OK;
1040}
1041
1042/**
1043 * Called by tcp_output() to actually send a TCP segment over IP.
1044 *
1045 * @param seg the tcp_seg to send
1046 * @param pcb the tcp_pcb for the TCP connection used to send the segment
1047 */
1048static void
1049tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
1050{
1051 u16_t len;
1052 struct netif *netif;
1053 u32_t *opts;
1054
1055 /** @bug Exclude retransmitted segments from this count. */
1056 snmp_inc_tcpoutsegs();
1057
1058 /* The TCP header has already been constructed, but the ackno and
1059 wnd fields remain. */
1060 seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
1061
1062 /* advertise our receive window size in this TCP segment */
1063 seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
1064
1065 pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
1066
1067 /* Add any requested options. NB MSS option is only set on SYN
1068 packets, so ignore it here */
1069 opts = (u32_t *)(void *)(seg->tcphdr + 1);
1070 if (seg->flags & TF_SEG_OPTS_MSS) {
1071 u16_t mss;
1072#if TCP_CALCULATE_EFF_SEND_MSS
1073 mss = tcp_eff_send_mss(TCP_MSS, &pcb->remote_ip);
1074#else /* TCP_CALCULATE_EFF_SEND_MSS */
1075 mss = TCP_MSS;
1076#endif /* TCP_CALCULATE_EFF_SEND_MSS */
1077 *opts = TCP_BUILD_MSS_OPTION(mss);
1078 opts += 1;
1079 }
1080#if LWIP_TCP_TIMESTAMPS
1081 pcb->ts_lastacksent = pcb->rcv_nxt;
1082
1083 if (seg->flags & TF_SEG_OPTS_TS) {
1084 tcp_build_timestamp_option(pcb, opts);
1085 opts += 3;
1086 }
1087#endif
1088
1089 /* Set retransmission timer running if it is not currently enabled
1090 This must be set before checking the route. */
1091 if (pcb->rtime == -1) {
1092 pcb->rtime = 0;
1093 }
1094
1095 /* If we don't have a local IP address, we get one by
1096 calling ip_route(). */
1097 if (ip_addr_isany(&(pcb->local_ip))) {
1098 netif = ip_route(&(pcb->remote_ip));
1099 if (netif == NULL) {
1100 return;
1101 }
1102 ip_addr_copy(pcb->local_ip, netif->ip_addr);
1103 }
1104
1105 if (pcb->rttest == 0) {
1106 pcb->rttest = tcp_ticks;
1107 pcb->rtseq = ntohl(seg->tcphdr->seqno);
1108
1109 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
1110 }
1111 LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
1112 htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
1113 seg->len));
1114
1115 len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload);
1116
1117 seg->p->len -= len;
1118 seg->p->tot_len -= len;
1119
1120 seg->p->payload = seg->tcphdr;
1121
1122 seg->tcphdr->chksum = 0;
1123#if CHECKSUM_GEN_TCP
1124#if TCP_CHECKSUM_ON_COPY
1125 {
1126 u32_t acc;
1127#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
1128 u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
1129 &(pcb->remote_ip),
1130 IP_PROTO_TCP, seg->p->tot_len);
1131#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
1132 if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
1133 LWIP_ASSERT("data included but not checksummed",
1134 seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
1135 }
1136
1137 /* rebuild TCP header checksum (TCP header changes for retransmissions!) */
1138 acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
1139 &(pcb->remote_ip),
1140 IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
1141 /* add payload checksum */
1142 if (seg->chksum_swapped) {
1143 seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
1144 seg->chksum_swapped = 0;
1145 }
1146 acc += (u16_t)~(seg->chksum);
1147 seg->tcphdr->chksum = FOLD_U32T(acc);
1148#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
1149 if (chksum_slow != seg->tcphdr->chksum) {
1150 LWIP_DEBUGF(TCP_DEBUG | LWIP_DBG_LEVEL_WARNING,
1151 ("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
1152 seg->tcphdr->chksum, chksum_slow));
1153 seg->tcphdr->chksum = chksum_slow;
1154 }
1155#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
1156 }
1157#else /* TCP_CHECKSUM_ON_COPY */
1158 seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
1159 &(pcb->remote_ip),
1160 IP_PROTO_TCP, seg->p->tot_len);
1161#endif /* TCP_CHECKSUM_ON_COPY */
1162#endif /* CHECKSUM_GEN_TCP */
1163 TCP_STATS_INC(tcp.xmit);
1164
1165#if LWIP_NETIF_HWADDRHINT
1166 ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
1167 IP_PROTO_TCP, &(pcb->addr_hint));
1168#else /* LWIP_NETIF_HWADDRHINT*/
1169 ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
1170 IP_PROTO_TCP);
1171#endif /* LWIP_NETIF_HWADDRHINT*/
1172}
1173
1174/**
1175 * Send a TCP RESET packet (empty segment with RST flag set) either to
1176 * abort a connection or to show that there is no matching local connection
1177 * for a received segment.
1178 *
1179 * Called by tcp_abort() (to abort a local connection), tcp_input() (if no
1180 * matching local pcb was found), tcp_listen_input() (if incoming segment
1181 * has ACK flag set) and tcp_process() (received segment in the wrong state)
1182 *
1183 * Since a RST segment is in most cases not sent for an active connection,
1184 * tcp_rst() has a number of arguments that are taken from a tcp_pcb for
1185 * most other segment output functions.
1186 *
1187 * @param seqno the sequence number to use for the outgoing segment
1188 * @param ackno the acknowledge number to use for the outgoing segment
1189 * @param local_ip the local IP address to send the segment from
1190 * @param remote_ip the remote IP address to send the segment to
1191 * @param local_port the local TCP port to send the segment from
1192 * @param remote_port the remote TCP port to send the segment to
1193 */
1194void
1195tcp_rst(u32_t seqno, u32_t ackno,
1196 ip_addr_t *local_ip, ip_addr_t *remote_ip,
1197 u16_t local_port, u16_t remote_port)
1198{
1199 struct pbuf *p;
1200 struct tcp_hdr *tcphdr;
1201 p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
1202 if (p == NULL) {
1203 LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
1204 return;
1205 }
1206 LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
1207 (p->len >= sizeof(struct tcp_hdr)));
1208
1209 tcphdr = (struct tcp_hdr *)p->payload;
1210 tcphdr->src = htons(local_port);
1211 tcphdr->dest = htons(remote_port);
1212 tcphdr->seqno = htonl(seqno);
1213 tcphdr->ackno = htonl(ackno);
1214 TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST | TCP_ACK);
1215 tcphdr->wnd = PP_HTONS(TCP_WND);
1216 tcphdr->chksum = 0;
1217 tcphdr->urgp = 0;
1218
1219#if CHECKSUM_GEN_TCP
1220 tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
1221 IP_PROTO_TCP, p->tot_len);
1222#endif
1223 TCP_STATS_INC(tcp.xmit);
1224 snmp_inc_tcpoutrsts();
1225 /* Send output with hardcoded TTL since we have no access to the pcb */
1226 ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
1227 pbuf_free(p);
1228 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
1229}
1230
1231/**
1232 * Requeue all unacked segments for retransmission
1233 *
1234 * Called by tcp_slowtmr() for slow retransmission.
1235 *
1236 * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
1237 */
1238void
1239tcp_rexmit_rto(struct tcp_pcb *pcb)
1240{
1241 struct tcp_seg *seg;
1242
1243 if (pcb->unacked == NULL) {
1244 return;
1245 }
1246
1247 /* Move all unacked segments to the head of the unsent queue */
1248 for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
1249 /* concatenate unsent queue after unacked queue */
1250 seg->next = pcb->unsent;
1251 /* unsent queue is the concatenated queue (of unacked, unsent) */
1252 pcb->unsent = pcb->unacked;
1253 /* unacked queue is now empty */
1254 pcb->unacked = NULL;
1255 /* last unsent hasn't changed, no need to reset unsent_oversize */
1256
1257 /* increment number of retransmissions */
1258 ++pcb->nrtx;
1259
1260 /* Don't take any RTT measurements after retransmitting. */
1261 pcb->rttest = 0;
1262
1263 /* Do the actual retransmission */
1264 tcp_output(pcb);
1265}
1266
1267/**
1268 * Requeue the first unacked segment for retransmission
1269 *
1270 * Called by tcp_receive() for fast retramsmit.
1271 *
1272 * @param pcb the tcp_pcb for which to retransmit the first unacked segment
1273 */
1274void
1275tcp_rexmit(struct tcp_pcb *pcb)
1276{
1277 struct tcp_seg *seg;
1278 struct tcp_seg **cur_seg;
1279
1280 if (pcb->unacked == NULL) {
1281 return;
1282 }
1283
1284 /* Move the first unacked segment to the unsent queue */
1285 /* Keep the unsent queue sorted. */
1286 seg = pcb->unacked;
1287 pcb->unacked = seg->next;
1288
1289 cur_seg = &(pcb->unsent);
1290 while (*cur_seg &&
1291 TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
1292 cur_seg = &((*cur_seg)->next );
1293 }
1294 seg->next = *cur_seg;
1295 *cur_seg = seg;
1296#if TCP_OVERSIZE
1297 if (seg->next == NULL) {
1298 /* the retransmitted segment is last in unsent, so reset unsent_oversize */
1299 pcb->unsent_oversize = 0;
1300 }
1301#endif /* TCP_OVERSIZE */
1302
1303 ++pcb->nrtx;
1304
1305 /* Don't take any rtt measurements after retransmitting. */
1306 pcb->rttest = 0;
1307
1308 /* Do the actual retransmission. */
1309 snmp_inc_tcpretranssegs();
1310 /* No need to call tcp_output: we are always called from tcp_input()
1311 and thus tcp_output directly returns. */
1312}
1313
1314
1315/**
1316 * Handle retransmission after three dupacks received
1317 *
1318 * @param pcb the tcp_pcb for which to retransmit the first unacked segment
1319 */
1320void
1321tcp_rexmit_fast(struct tcp_pcb *pcb)
1322{
1323 if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
1324 /* This is fast retransmit. Retransmit the first unacked segment. */
1325 LWIP_DEBUGF(TCP_FR_DEBUG,
1326 ("tcp_receive: dupacks %"U16_F" (%"U32_F
1327 "), fast retransmit %"U32_F"\n",
1328 (u16_t)pcb->dupacks, pcb->lastack,
1329 ntohl(pcb->unacked->tcphdr->seqno)));
1330 tcp_rexmit(pcb);
1331
1332 /* Set ssthresh to half of the minimum of the current
1333 * cwnd and the advertised window */
1334 if (pcb->cwnd > pcb->snd_wnd) {
1335 pcb->ssthresh = pcb->snd_wnd / 2;
1336 } else {
1337 pcb->ssthresh = pcb->cwnd / 2;
1338 }
1339
1340 /* The minimum value for ssthresh should be 2 MSS */
1341 if (pcb->ssthresh < 2*pcb->mss) {
1342 LWIP_DEBUGF(TCP_FR_DEBUG,
1343 ("tcp_receive: The minimum value for ssthresh %"U16_F
1344 " should be min 2 mss %"U16_F"...\n",
1345 pcb->ssthresh, 2*pcb->mss));
1346 pcb->ssthresh = 2*pcb->mss;
1347 }
1348
1349 pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
1350 pcb->flags |= TF_INFR;
1351 }
1352}
1353
1354
1355/**
1356 * Send keepalive packets to keep a connection active although
1357 * no data is sent over it.
1358 *
1359 * Called by tcp_slowtmr()
1360 *
1361 * @param pcb the tcp_pcb for which to send a keepalive packet
1362 */
1363void
1364tcp_keepalive(struct tcp_pcb *pcb)
1365{
1366 struct pbuf *p;
1367 struct tcp_hdr *tcphdr;
1368
1369 LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
1370 ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
1371 ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
1372
1373 LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
1374 tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
1375
1376 p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
1377 if(p == NULL) {
1378 LWIP_DEBUGF(TCP_DEBUG,
1379 ("tcp_keepalive: could not allocate memory for pbuf\n"));
1380 return;
1381 }
1382 tcphdr = (struct tcp_hdr *)p->payload;
1383
1384#if CHECKSUM_GEN_TCP
1385 tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
1386 IP_PROTO_TCP, p->tot_len);
1387#endif
1388 TCP_STATS_INC(tcp.xmit);
1389
1390 /* Send output to IP */
1391#if LWIP_NETIF_HWADDRHINT
1392 ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
1393 &(pcb->addr_hint));
1394#else /* LWIP_NETIF_HWADDRHINT*/
1395 ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
1396#endif /* LWIP_NETIF_HWADDRHINT*/
1397
1398 pbuf_free(p);
1399
1400 LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
1401 pcb->snd_nxt - 1, pcb->rcv_nxt));
1402}
1403
1404
1405/**
1406 * Send persist timer zero-window probes to keep a connection active
1407 * when a window update is lost.
1408 *
1409 * Called by tcp_slowtmr()
1410 *
1411 * @param pcb the tcp_pcb for which to send a zero-window probe packet
1412 */
1413void
1414tcp_zero_window_probe(struct tcp_pcb *pcb)
1415{
1416 struct pbuf *p;
1417 struct tcp_hdr *tcphdr;
1418 struct tcp_seg *seg;
1419 u16_t len;
1420 u8_t is_fin;
1421
1422 LWIP_DEBUGF(TCP_DEBUG,
1423 ("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
1424 U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
1425 ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
1426 ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
1427
1428 LWIP_DEBUGF(TCP_DEBUG,
1429 ("tcp_zero_window_probe: tcp_ticks %"U32_F
1430 " pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
1431 tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
1432
1433 seg = pcb->unacked;
1434
1435 if(seg == NULL) {
1436 seg = pcb->unsent;
1437 }
1438 if(seg == NULL) {
1439 return;
1440 }
1441
1442 is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
1443 /* we want to send one seqno: either FIN or data (no options) */
1444 len = is_fin ? 0 : 1;
1445
1446 p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
1447 if(p == NULL) {
1448 LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
1449 return;
1450 }
1451 tcphdr = (struct tcp_hdr *)p->payload;
1452
1453 if (is_fin) {
1454 /* FIN segment, no data */
1455 TCPH_FLAGS_SET(tcphdr, TCP_ACK | TCP_FIN);
1456 } else {
1457 /* Data segment, copy in one byte from the head of the unacked queue */
1458 char *d = ((char *)p->payload + TCP_HLEN);
1459 /* Depending on whether the segment has already been sent (unacked) or not
1460 (unsent), seg->p->payload points to the IP header or TCP header.
1461 Ensure we copy the first TCP data byte: */
1462 pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len);
1463 }
1464
1465#if CHECKSUM_GEN_TCP
1466 tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
1467 IP_PROTO_TCP, p->tot_len);
1468#endif
1469 TCP_STATS_INC(tcp.xmit);
1470
1471 /* Send output to IP */
1472#if LWIP_NETIF_HWADDRHINT
1473 ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
1474 &(pcb->addr_hint));
1475#else /* LWIP_NETIF_HWADDRHINT*/
1476 ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
1477#endif /* LWIP_NETIF_HWADDRHINT*/
1478
1479 pbuf_free(p);
1480
1481 LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
1482 " ackno %"U32_F".\n",
1483 pcb->snd_nxt - 1, pcb->rcv_nxt));
1484}
1485#endif /* LWIP_TCP */
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