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lwip/core/tcp_out.c@0:d616ece2d859, 2010-09-18 (annotated)

Committer:: mbed714
Date:: Sat Sep 18 23:05:49 2010 +0000
Revision:: 0:d616ece2d859

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User	Revision	Line number	New contents of line
mbed714	0:d616ece2d859	1	/**
mbed714	0:d616ece2d859	2	* @file
mbed714	0:d616ece2d859	3	* Transmission Control Protocol, outgoing traffic
mbed714	0:d616ece2d859	4	*
mbed714	0:d616ece2d859	5	* The output functions of TCP.
mbed714	0:d616ece2d859	6	*
mbed714	0:d616ece2d859	7	*/
mbed714	0:d616ece2d859	8
mbed714	0:d616ece2d859	9	/*
mbed714	0:d616ece2d859	10	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
mbed714	0:d616ece2d859	11	* All rights reserved.
mbed714	0:d616ece2d859	12	*
mbed714	0:d616ece2d859	13	* Redistribution and use in source and binary forms, with or without modification,
mbed714	0:d616ece2d859	14	* are permitted provided that the following conditions are met:
mbed714	0:d616ece2d859	15	*
mbed714	0:d616ece2d859	16	* 1. Redistributions of source code must retain the above copyright notice,
mbed714	0:d616ece2d859	17	* this list of conditions and the following disclaimer.
mbed714	0:d616ece2d859	18	* 2. Redistributions in binary form must reproduce the above copyright notice,
mbed714	0:d616ece2d859	19	* this list of conditions and the following disclaimer in the documentation
mbed714	0:d616ece2d859	20	* and/or other materials provided with the distribution.
mbed714	0:d616ece2d859	21	* 3. The name of the author may not be used to endorse or promote products
mbed714	0:d616ece2d859	22	* derived from this software without specific prior written permission.
mbed714	0:d616ece2d859	23	*
mbed714	0:d616ece2d859	24	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
mbed714	0:d616ece2d859	25	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
mbed714	0:d616ece2d859	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
mbed714	0:d616ece2d859	27	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
mbed714	0:d616ece2d859	28	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
mbed714	0:d616ece2d859	29	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
mbed714	0:d616ece2d859	30	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
mbed714	0:d616ece2d859	31	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
mbed714	0:d616ece2d859	32	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
mbed714	0:d616ece2d859	33	* OF SUCH DAMAGE.
mbed714	0:d616ece2d859	34	*
mbed714	0:d616ece2d859	35	* This file is part of the lwIP TCP/IP stack.
mbed714	0:d616ece2d859	36	*
mbed714	0:d616ece2d859	37	* Author: Adam Dunkels <adam@sics.se>
mbed714	0:d616ece2d859	38	*
mbed714	0:d616ece2d859	39	*/
mbed714	0:d616ece2d859	40
mbed714	0:d616ece2d859	41	#include "lwip/opt.h"
mbed714	0:d616ece2d859	42
mbed714	0:d616ece2d859	43	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
mbed714	0:d616ece2d859	44
mbed714	0:d616ece2d859	45	#include "lwip/tcp_impl.h"
mbed714	0:d616ece2d859	46	#include "lwip/def.h"
mbed714	0:d616ece2d859	47	#include "lwip/mem.h"
mbed714	0:d616ece2d859	48	#include "lwip/memp.h"
mbed714	0:d616ece2d859	49	#include "lwip/sys.h"
mbed714	0:d616ece2d859	50	#include "lwip/ip_addr.h"
mbed714	0:d616ece2d859	51	#include "lwip/netif.h"
mbed714	0:d616ece2d859	52	#include "lwip/inet_chksum.h"
mbed714	0:d616ece2d859	53	#include "lwip/stats.h"
mbed714	0:d616ece2d859	54	#include "lwip/snmp.h"
mbed714	0:d616ece2d859	55
mbed714	0:d616ece2d859	56	#include <string.h>
mbed714	0:d616ece2d859	57
mbed714	0:d616ece2d859	58	/* Define some copy-macros for checksum-on-copy so that the code looks
mbed714	0:d616ece2d859	59	nicer by preventing too many ifdef's. */
mbed714	0:d616ece2d859	60	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	61	#define TCP_DATA_COPY(dst, src, len, seg) do { \
mbed714	0:d616ece2d859	62	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
mbed714	0:d616ece2d859	63	len, &seg->chksum, &seg->chksum_swapped); \
mbed714	0:d616ece2d859	64	seg->flags \|= TF_SEG_DATA_CHECKSUMMED; } while(0)
mbed714	0:d616ece2d859	65	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
mbed714	0:d616ece2d859	66	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
mbed714	0:d616ece2d859	67	#else /* TCP_CHECKSUM_ON_COPY*/
mbed714	0:d616ece2d859	68	#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
mbed714	0:d616ece2d859	69	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
mbed714	0:d616ece2d859	70	#endif /* TCP_CHECKSUM_ON_COPY*/
mbed714	0:d616ece2d859	71
mbed714	0:d616ece2d859	72	/** Define this to 1 for an extra check that the output checksum is valid
mbed714	0:d616ece2d859	73	* (usefule when the checksum is generated by the application, not the stack) */
mbed714	0:d616ece2d859	74	#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
mbed714	0:d616ece2d859	75	#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
mbed714	0:d616ece2d859	76	#endif
mbed714	0:d616ece2d859	77
mbed714	0:d616ece2d859	78	/* Forward declarations.*/
mbed714	0:d616ece2d859	79	static void tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb);
mbed714	0:d616ece2d859	80
mbed714	0:d616ece2d859	81	/** Allocate a pbuf and create a tcphdr at p->payload, used for output
mbed714	0:d616ece2d859	82	* functions other than the default tcp_output -> tcp_output_segment
mbed714	0:d616ece2d859	83	* (e.g. tcp_send_empty_ack, etc.)
mbed714	0:d616ece2d859	84	*
mbed714	0:d616ece2d859	85	* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
mbed714	0:d616ece2d859	86	* @param optlen length of header-options
mbed714	0:d616ece2d859	87	* @param datalen length of tcp data to reserve in pbuf
mbed714	0:d616ece2d859	88	* @param seqno_be seqno in network byte order (big-endian)
mbed714	0:d616ece2d859	89	* @return pbuf with p->payload being the tcp_hdr
mbed714	0:d616ece2d859	90	*/
mbed714	0:d616ece2d859	91	static struct pbuf *
mbed714	0:d616ece2d859	92	tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
mbed714	0:d616ece2d859	93	u32_t seqno_be /* already in network byte order */)
mbed714	0:d616ece2d859	94	{
mbed714	0:d616ece2d859	95	struct tcp_hdr *tcphdr;
mbed714	0:d616ece2d859	96	struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
mbed714	0:d616ece2d859	97	if (p != NULL) {
mbed714	0:d616ece2d859	98	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
mbed714	0:d616ece2d859	99	(p->len >= TCP_HLEN + optlen));
mbed714	0:d616ece2d859	100	tcphdr = (struct tcp_hdr *)p->payload;
mbed714	0:d616ece2d859	101	tcphdr->src = htons(pcb->local_port);
mbed714	0:d616ece2d859	102	tcphdr->dest = htons(pcb->remote_port);
mbed714	0:d616ece2d859	103	tcphdr->seqno = seqno_be;
mbed714	0:d616ece2d859	104	tcphdr->ackno = htonl(pcb->rcv_nxt);
mbed714	0:d616ece2d859	105	TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
mbed714	0:d616ece2d859	106	tcphdr->wnd = htons(pcb->rcv_ann_wnd);
mbed714	0:d616ece2d859	107	tcphdr->chksum = 0;
mbed714	0:d616ece2d859	108	tcphdr->urgp = 0;
mbed714	0:d616ece2d859	109
mbed714	0:d616ece2d859	110	/* If we're sending a packet, update the announced right window edge */
mbed714	0:d616ece2d859	111	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
mbed714	0:d616ece2d859	112	}
mbed714	0:d616ece2d859	113	return p;
mbed714	0:d616ece2d859	114	}
mbed714	0:d616ece2d859	115
mbed714	0:d616ece2d859	116	/**
mbed714	0:d616ece2d859	117	* Called by tcp_close() to send a segment including FIN flag but not data.
mbed714	0:d616ece2d859	118	*
mbed714	0:d616ece2d859	119	* @param pcb the tcp_pcb over which to send a segment
mbed714	0:d616ece2d859	120	* @return ERR_OK if sent, another err_t otherwise
mbed714	0:d616ece2d859	121	*/
mbed714	0:d616ece2d859	122	err_t
mbed714	0:d616ece2d859	123	tcp_send_fin(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	124	{
mbed714	0:d616ece2d859	125	/* first, try to add the fin to the last unsent segment */
mbed714	0:d616ece2d859	126	if (pcb->unsent != NULL) {
mbed714	0:d616ece2d859	127	struct tcp_seg *last_unsent;
mbed714	0:d616ece2d859	128	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
mbed714	0:d616ece2d859	129	last_unsent = last_unsent->next);
mbed714	0:d616ece2d859	130
mbed714	0:d616ece2d859	131	if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN \| TCP_FIN \| TCP_RST)) == 0) {
mbed714	0:d616ece2d859	132	/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
mbed714	0:d616ece2d859	133	TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
mbed714	0:d616ece2d859	134	return ERR_OK;
mbed714	0:d616ece2d859	135	}
mbed714	0:d616ece2d859	136	}
mbed714	0:d616ece2d859	137	/* no data, no length, flags, copy=1, no optdata */
mbed714	0:d616ece2d859	138	return tcp_enqueue_flags(pcb, TCP_FIN);
mbed714	0:d616ece2d859	139	}
mbed714	0:d616ece2d859	140
mbed714	0:d616ece2d859	141	/**
mbed714	0:d616ece2d859	142	* Create a TCP segment with prefilled header.
mbed714	0:d616ece2d859	143	*
mbed714	0:d616ece2d859	144	* Called by tcp_write and tcp_enqueue_flags.
mbed714	0:d616ece2d859	145	*
mbed714	0:d616ece2d859	146	* @param pcb Protocol control block for the TCP connection.
mbed714	0:d616ece2d859	147	* @param p pbuf that is used to hold the TCP header.
mbed714	0:d616ece2d859	148	* @param flags TCP flags for header.
mbed714	0:d616ece2d859	149	* @param seqno TCP sequence number of this packet
mbed714	0:d616ece2d859	150	* @param optflags options to include in TCP header
mbed714	0:d616ece2d859	151	* @return a new tcp_seg pointing to p, or NULL.
mbed714	0:d616ece2d859	152	* The TCP header is filled in except ackno and wnd.
mbed714	0:d616ece2d859	153	* p is freed on failure.
mbed714	0:d616ece2d859	154	*/
mbed714	0:d616ece2d859	155	static struct tcp_seg *
mbed714	0:d616ece2d859	156	tcp_create_segment(struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
mbed714	0:d616ece2d859	157	{
mbed714	0:d616ece2d859	158	struct tcp_seg *seg;
mbed714	0:d616ece2d859	159	u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
mbed714	0:d616ece2d859	160
mbed714	0:d616ece2d859	161	if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
mbed714	0:d616ece2d859	162	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no memory.\n"));
mbed714	0:d616ece2d859	163	pbuf_free(p);
mbed714	0:d616ece2d859	164	return NULL;
mbed714	0:d616ece2d859	165	}
mbed714	0:d616ece2d859	166	seg->flags = optflags;
mbed714	0:d616ece2d859	167	seg->next = NULL;
mbed714	0:d616ece2d859	168	seg->p = p;
mbed714	0:d616ece2d859	169	seg->dataptr = p->payload;
mbed714	0:d616ece2d859	170	seg->len = p->tot_len - optlen;
mbed714	0:d616ece2d859	171	#if TCP_OVERSIZE_DBGCHECK
mbed714	0:d616ece2d859	172	seg->oversize_left = 0;
mbed714	0:d616ece2d859	173	#endif /* TCP_OVERSIZE_DBGCHECK */
mbed714	0:d616ece2d859	174	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	175	seg->chksum = 0;
mbed714	0:d616ece2d859	176	seg->chksum_swapped = 0;
mbed714	0:d616ece2d859	177	/* check optflags */
mbed714	0:d616ece2d859	178	LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
mbed714	0:d616ece2d859	179	(optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
mbed714	0:d616ece2d859	180	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	181
mbed714	0:d616ece2d859	182	/* build TCP header */
mbed714	0:d616ece2d859	183	if (pbuf_header(p, TCP_HLEN)) {
mbed714	0:d616ece2d859	184	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
mbed714	0:d616ece2d859	185	TCP_STATS_INC(tcp.err);
mbed714	0:d616ece2d859	186	tcp_seg_free(seg);
mbed714	0:d616ece2d859	187	return NULL;
mbed714	0:d616ece2d859	188	}
mbed714	0:d616ece2d859	189	seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
mbed714	0:d616ece2d859	190	seg->tcphdr->src = htons(pcb->local_port);
mbed714	0:d616ece2d859	191	seg->tcphdr->dest = htons(pcb->remote_port);
mbed714	0:d616ece2d859	192	seg->tcphdr->seqno = htonl(seqno);
mbed714	0:d616ece2d859	193	/* ackno is set in tcp_output */
mbed714	0:d616ece2d859	194	TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
mbed714	0:d616ece2d859	195	/* wnd and chksum are set in tcp_output */
mbed714	0:d616ece2d859	196	seg->tcphdr->urgp = 0;
mbed714	0:d616ece2d859	197	return seg;
mbed714	0:d616ece2d859	198	}
mbed714	0:d616ece2d859	199
mbed714	0:d616ece2d859	200	/**
mbed714	0:d616ece2d859	201	* Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
mbed714	0:d616ece2d859	202	*
mbed714	0:d616ece2d859	203	* This function is like pbuf_alloc(layer, length, PBUF_RAM) except
mbed714	0:d616ece2d859	204	* there may be extra bytes available at the end.
mbed714	0:d616ece2d859	205	*
mbed714	0:d616ece2d859	206	* @param layer flag to define header size.
mbed714	0:d616ece2d859	207	* @param length size of the pbuf's payload.
mbed714	0:d616ece2d859	208	* @param max_length maximum usable size of payload+oversize.
mbed714	0:d616ece2d859	209	* @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
mbed714	0:d616ece2d859	210	* @param pcb The TCP connection that willo enqueue the pbuf.
mbed714	0:d616ece2d859	211	* @param apiflags API flags given to tcp_write.
mbed714	0:d616ece2d859	212	* @param first_seg true when this pbuf will be used in the first enqueued segment.
mbed714	0:d616ece2d859	213	* @param
mbed714	0:d616ece2d859	214	*/
mbed714	0:d616ece2d859	215	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	216	static struct pbuf *
mbed714	0:d616ece2d859	217	tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
mbed714	0:d616ece2d859	218	u16_t oversize, struct tcp_pcb pcb, u8_t apiflags,
mbed714	0:d616ece2d859	219	u8_t first_seg)
mbed714	0:d616ece2d859	220	{
mbed714	0:d616ece2d859	221	struct pbuf *p;
mbed714	0:d616ece2d859	222	u16_t alloc = length;
mbed714	0:d616ece2d859	223
mbed714	0:d616ece2d859	224	#if LWIP_NETIF_TX_SINGLE_PBUF
mbed714	0:d616ece2d859	225	LWIP_UNUSED_ARG(max_length);
mbed714	0:d616ece2d859	226	LWIP_UNUSED_ARG(pcb);
mbed714	0:d616ece2d859	227	LWIP_UNUSED_ARG(apiflags);
mbed714	0:d616ece2d859	228	LWIP_UNUSED_ARG(first_seg);
mbed714	0:d616ece2d859	229	/* always create MSS-sized pbufs */
mbed714	0:d616ece2d859	230	alloc = TCP_MSS;
mbed714	0:d616ece2d859	231	#else /* LWIP_NETIF_TX_SINGLE_PBUF */
mbed714	0:d616ece2d859	232	if (length < max_length) {
mbed714	0:d616ece2d859	233	/* Should we allocate an oversized pbuf, or just the minimum
mbed714	0:d616ece2d859	234	* length required? If tcp_write is going to be called again
mbed714	0:d616ece2d859	235	* before this segment is transmitted, we want the oversized
mbed714	0:d616ece2d859	236	* buffer. If the segment will be transmitted immediately, we can
mbed714	0:d616ece2d859	237	* save memory by allocating only length. We use a simple
mbed714	0:d616ece2d859	238	* heuristic based on the following information:
mbed714	0:d616ece2d859	239	*
mbed714	0:d616ece2d859	240	* Did the user set TCP_WRITE_FLAG_MORE?
mbed714	0:d616ece2d859	241	*
mbed714	0:d616ece2d859	242	* Will the Nagle algorithm defer transmission of this segment?
mbed714	0:d616ece2d859	243	*/
mbed714	0:d616ece2d859	244	if ((apiflags & TCP_WRITE_FLAG_MORE) \|\|
mbed714	0:d616ece2d859	245	(!(pcb->flags & TF_NODELAY) &&
mbed714	0:d616ece2d859	246	(!first_seg \|\|
mbed714	0:d616ece2d859	247	pcb->unsent != NULL \|\|
mbed714	0:d616ece2d859	248	pcb->unacked != NULL))) {
mbed714	0:d616ece2d859	249	alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
mbed714	0:d616ece2d859	250	}
mbed714	0:d616ece2d859	251	}
mbed714	0:d616ece2d859	252	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
mbed714	0:d616ece2d859	253	p = pbuf_alloc(layer, alloc, PBUF_RAM);
mbed714	0:d616ece2d859	254	if (p == NULL) {
mbed714	0:d616ece2d859	255	return NULL;
mbed714	0:d616ece2d859	256	}
mbed714	0:d616ece2d859	257	LWIP_ASSERT("need unchained pbuf", p->next == NULL);
mbed714	0:d616ece2d859	258	*oversize = p->len - length;
mbed714	0:d616ece2d859	259	/* trim p->len to the currently used size */
mbed714	0:d616ece2d859	260	p->len = p->tot_len = length;
mbed714	0:d616ece2d859	261	return p;
mbed714	0:d616ece2d859	262	}
mbed714	0:d616ece2d859	263	#else /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	264	#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
mbed714	0:d616ece2d859	265	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	266
mbed714	0:d616ece2d859	267	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	268	/** Add a checksum of newly added data to the segment */
mbed714	0:d616ece2d859	269	static void
mbed714	0:d616ece2d859	270	tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
mbed714	0:d616ece2d859	271	u8_t *seg_chksum_swapped)
mbed714	0:d616ece2d859	272	{
mbed714	0:d616ece2d859	273	u32_t helper;
mbed714	0:d616ece2d859	274	/* add chksum to old chksum and fold to u16_t */
mbed714	0:d616ece2d859	275	helper = chksum + *seg_chksum;
mbed714	0:d616ece2d859	276	chksum = FOLD_U32T(helper);
mbed714	0:d616ece2d859	277	if ((len & 1) != 0) {
mbed714	0:d616ece2d859	278	seg_chksum_swapped = 1 - seg_chksum_swapped;
mbed714	0:d616ece2d859	279	chksum = SWAP_BYTES_IN_WORD(chksum);
mbed714	0:d616ece2d859	280	}
mbed714	0:d616ece2d859	281	*seg_chksum = chksum;
mbed714	0:d616ece2d859	282	}
mbed714	0:d616ece2d859	283	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	284
mbed714	0:d616ece2d859	285	/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
mbed714	0:d616ece2d859	286	*
mbed714	0:d616ece2d859	287	* @param pcb the tcp pcb to check for
mbed714	0:d616ece2d859	288	* @param len length of data to send (checked agains snd_buf)
mbed714	0:d616ece2d859	289	* @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
mbed714	0:d616ece2d859	290	*/
mbed714	0:d616ece2d859	291	static err_t
mbed714	0:d616ece2d859	292	tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
mbed714	0:d616ece2d859	293	{
mbed714	0:d616ece2d859	294	/* connection is in invalid state for data transmission? */
mbed714	0:d616ece2d859	295	if ((pcb->state != ESTABLISHED) &&
mbed714	0:d616ece2d859	296	(pcb->state != CLOSE_WAIT) &&
mbed714	0:d616ece2d859	297	(pcb->state != SYN_SENT) &&
mbed714	0:d616ece2d859	298	(pcb->state != SYN_RCVD)) {
mbed714	0:d616ece2d859	299	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_STATE \| LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
mbed714	0:d616ece2d859	300	return ERR_CONN;
mbed714	0:d616ece2d859	301	} else if (len == 0) {
mbed714	0:d616ece2d859	302	return ERR_OK;
mbed714	0:d616ece2d859	303	}
mbed714	0:d616ece2d859	304
mbed714	0:d616ece2d859	305	/* fail on too much data */
mbed714	0:d616ece2d859	306	if (len > pcb->snd_buf) {
mbed714	0:d616ece2d859	307	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
mbed714	0:d616ece2d859	308	len, pcb->snd_buf));
mbed714	0:d616ece2d859	309	pcb->flags \|= TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	310	return ERR_MEM;
mbed714	0:d616ece2d859	311	}
mbed714	0:d616ece2d859	312
mbed714	0:d616ece2d859	313	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	314
mbed714	0:d616ece2d859	315	/* If total number of pbufs on the unsent/unacked queues exceeds the
mbed714	0:d616ece2d859	316	* configured maximum, return an error */
mbed714	0:d616ece2d859	317	/* check for configured max queuelen and possible overflow */
mbed714	0:d616ece2d859	318	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
mbed714	0:d616ece2d859	319	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
mbed714	0:d616ece2d859	320	pcb->snd_queuelen, TCP_SND_QUEUELEN));
mbed714	0:d616ece2d859	321	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	322	pcb->flags \|= TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	323	return ERR_MEM;
mbed714	0:d616ece2d859	324	}
mbed714	0:d616ece2d859	325	if (pcb->snd_queuelen != 0) {
mbed714	0:d616ece2d859	326	LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
mbed714	0:d616ece2d859	327	pcb->unacked != NULL \|\| pcb->unsent != NULL);
mbed714	0:d616ece2d859	328	} else {
mbed714	0:d616ece2d859	329	LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
mbed714	0:d616ece2d859	330	pcb->unacked == NULL && pcb->unsent == NULL);
mbed714	0:d616ece2d859	331	}
mbed714	0:d616ece2d859	332	return ERR_OK;
mbed714	0:d616ece2d859	333	}
mbed714	0:d616ece2d859	334
mbed714	0:d616ece2d859	335	/**
mbed714	0:d616ece2d859	336	* Write data for sending (but does not send it immediately).
mbed714	0:d616ece2d859	337	*
mbed714	0:d616ece2d859	338	* It waits in the expectation of more data being sent soon (as
mbed714	0:d616ece2d859	339	* it can send them more efficiently by combining them together).
mbed714	0:d616ece2d859	340	* To prompt the system to send data now, call tcp_output() after
mbed714	0:d616ece2d859	341	* calling tcp_write().
mbed714	0:d616ece2d859	342	*
mbed714	0:d616ece2d859	343	* @param pcb Protocol control block for the TCP connection to enqueue data for.
mbed714	0:d616ece2d859	344	* @param arg Pointer to the data to be enqueued for sending.
mbed714	0:d616ece2d859	345	* @param len Data length in bytes
mbed714	0:d616ece2d859	346	* @param apiflags combination of following flags :
mbed714	0:d616ece2d859	347	* - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
mbed714	0:d616ece2d859	348	* - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
mbed714	0:d616ece2d859	349	* @return ERR_OK if enqueued, another err_t on error
mbed714	0:d616ece2d859	350	*/
mbed714	0:d616ece2d859	351	err_t
mbed714	0:d616ece2d859	352	tcp_write(struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
mbed714	0:d616ece2d859	353	{
mbed714	0:d616ece2d859	354	struct pbuf *concat_p = NULL;
mbed714	0:d616ece2d859	355	struct tcp_seg last_unsent = NULL, seg = NULL, prev_seg = NULL, queue = NULL;
mbed714	0:d616ece2d859	356	u16_t pos = 0; /* position in 'arg' data */
mbed714	0:d616ece2d859	357	u16_t queuelen;
mbed714	0:d616ece2d859	358	u8_t optlen = 0;
mbed714	0:d616ece2d859	359	u8_t optflags = 0;
mbed714	0:d616ece2d859	360	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	361	u16_t oversize = 0;
mbed714	0:d616ece2d859	362	u16_t oversize_used = 0;
mbed714	0:d616ece2d859	363	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	364	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	365	u16_t concat_chksum = 0;
mbed714	0:d616ece2d859	366	u8_t concat_chksum_swapped = 0;
mbed714	0:d616ece2d859	367	u16_t concat_chksummed = 0;
mbed714	0:d616ece2d859	368	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	369	err_t err;
mbed714	0:d616ece2d859	370
mbed714	0:d616ece2d859	371	#if LWIP_NETIF_TX_SINGLE_PBUF
mbed714	0:d616ece2d859	372	/* Always copy to try to create single pbufs for TX */
mbed714	0:d616ece2d859	373	apiflags \|= TCP_WRITE_FLAG_COPY;
mbed714	0:d616ece2d859	374	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
mbed714	0:d616ece2d859	375
mbed714	0:d616ece2d859	376	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
mbed714	0:d616ece2d859	377	(void *)pcb, arg, len, (u16_t)apiflags));
mbed714	0:d616ece2d859	378	LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
mbed714	0:d616ece2d859	379	arg != NULL, return ERR_ARG;);
mbed714	0:d616ece2d859	380
mbed714	0:d616ece2d859	381	err = tcp_write_checks(pcb, len);
mbed714	0:d616ece2d859	382	if (err != ERR_OK) {
mbed714	0:d616ece2d859	383	return err;
mbed714	0:d616ece2d859	384	}
mbed714	0:d616ece2d859	385	queuelen = pcb->snd_queuelen;
mbed714	0:d616ece2d859	386
mbed714	0:d616ece2d859	387	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	388	if ((pcb->flags & TF_TIMESTAMP)) {
mbed714	0:d616ece2d859	389	optflags = TF_SEG_OPTS_TS;
mbed714	0:d616ece2d859	390	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
mbed714	0:d616ece2d859	391	}
mbed714	0:d616ece2d859	392	#endif /* LWIP_TCP_TIMESTAMPS */
mbed714	0:d616ece2d859	393
mbed714	0:d616ece2d859	394
mbed714	0:d616ece2d859	395	/*
mbed714	0:d616ece2d859	396	* TCP segmentation is done in three phases with increasing complexity:
mbed714	0:d616ece2d859	397	*
mbed714	0:d616ece2d859	398	* 1. Copy data directly into an oversized pbuf.
mbed714	0:d616ece2d859	399	* 2. Chain a new pbuf to the end of pcb->unsent.
mbed714	0:d616ece2d859	400	* 3. Create new segments.
mbed714	0:d616ece2d859	401	*
mbed714	0:d616ece2d859	402	* We may run out of memory at any point. In that case we must
mbed714	0:d616ece2d859	403	* return ERR_MEM and not change anything in pcb. Therefore, all
mbed714	0:d616ece2d859	404	* changes are recorded in local variables and committed at the end
mbed714	0:d616ece2d859	405	* of the function. Some pcb fields are maintained in local copies:
mbed714	0:d616ece2d859	406	*
mbed714	0:d616ece2d859	407	* queuelen = pcb->snd_queuelen
mbed714	0:d616ece2d859	408	* oversize = pcb->unsent_oversize
mbed714	0:d616ece2d859	409	*
mbed714	0:d616ece2d859	410	* These variables are set consistently by the phases:
mbed714	0:d616ece2d859	411	*
mbed714	0:d616ece2d859	412	* seg points to the last segment tampered with.
mbed714	0:d616ece2d859	413	*
mbed714	0:d616ece2d859	414	* pos records progress as data is segmented.
mbed714	0:d616ece2d859	415	*/
mbed714	0:d616ece2d859	416
mbed714	0:d616ece2d859	417	/* Find the tail of the unsent queue. */
mbed714	0:d616ece2d859	418	if (pcb->unsent != NULL) {
mbed714	0:d616ece2d859	419	u16_t space;
mbed714	0:d616ece2d859	420	u16_t unsent_optlen;
mbed714	0:d616ece2d859	421
mbed714	0:d616ece2d859	422	/* @todo: this could be sped up by keeping last_unsent in the pcb */
mbed714	0:d616ece2d859	423	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
mbed714	0:d616ece2d859	424	last_unsent = last_unsent->next);
mbed714	0:d616ece2d859	425
mbed714	0:d616ece2d859	426	/* Usable space at the end of the last unsent segment */
mbed714	0:d616ece2d859	427	unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
mbed714	0:d616ece2d859	428	space = pcb->mss - (last_unsent->len + unsent_optlen);
mbed714	0:d616ece2d859	429
mbed714	0:d616ece2d859	430	/*
mbed714	0:d616ece2d859	431	* Phase 1: Copy data directly into an oversized pbuf.
mbed714	0:d616ece2d859	432	*
mbed714	0:d616ece2d859	433	* The number of bytes copied is recorded in the oversize_used
mbed714	0:d616ece2d859	434	* variable. The actual copying is done at the bottom of the
mbed714	0:d616ece2d859	435	* function.
mbed714	0:d616ece2d859	436	*/
mbed714	0:d616ece2d859	437	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	438	#if TCP_OVERSIZE_DBGCHECK
mbed714	0:d616ece2d859	439	/* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
mbed714	0:d616ece2d859	440	LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
mbed714	0:d616ece2d859	441	pcb->unsent_oversize == last_unsent->oversize_left);
mbed714	0:d616ece2d859	442	#endif /* TCP_OVERSIZE_DBGCHECK */
mbed714	0:d616ece2d859	443	oversize = pcb->unsent_oversize;
mbed714	0:d616ece2d859	444	if (oversize > 0) {
mbed714	0:d616ece2d859	445	LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
mbed714	0:d616ece2d859	446	seg = last_unsent;
mbed714	0:d616ece2d859	447	oversize_used = oversize < len ? oversize : len;
mbed714	0:d616ece2d859	448	pos += oversize_used;
mbed714	0:d616ece2d859	449	oversize -= oversize_used;
mbed714	0:d616ece2d859	450	space -= oversize_used;
mbed714	0:d616ece2d859	451	}
mbed714	0:d616ece2d859	452	/* now we are either finished or oversize is zero */
mbed714	0:d616ece2d859	453	LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) \|\| (pos == len));
mbed714	0:d616ece2d859	454	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	455
mbed714	0:d616ece2d859	456	/*
mbed714	0:d616ece2d859	457	* Phase 2: Chain a new pbuf to the end of pcb->unsent.
mbed714	0:d616ece2d859	458	*
mbed714	0:d616ece2d859	459	* We don't extend segments containing SYN/FIN flags or options
mbed714	0:d616ece2d859	460	* (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
mbed714	0:d616ece2d859	461	* the end.
mbed714	0:d616ece2d859	462	*/
mbed714	0:d616ece2d859	463	if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
mbed714	0:d616ece2d859	464	u16_t seglen = space < len - pos ? space : len - pos;
mbed714	0:d616ece2d859	465	seg = last_unsent;
mbed714	0:d616ece2d859	466
mbed714	0:d616ece2d859	467	/* Create a pbuf with a copy or reference to seglen bytes. We
mbed714	0:d616ece2d859	468	* can use PBUF_RAW here since the data appears in the middle of
mbed714	0:d616ece2d859	469	* a segment. A header will never be prepended. */
mbed714	0:d616ece2d859	470	if (apiflags & TCP_WRITE_FLAG_COPY) {
mbed714	0:d616ece2d859	471	/* Data is copied */
mbed714	0:d616ece2d859	472	if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
mbed714	0:d616ece2d859	473	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
mbed714	0:d616ece2d859	474	("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
mbed714	0:d616ece2d859	475	seglen));
mbed714	0:d616ece2d859	476	goto memerr;
mbed714	0:d616ece2d859	477	}
mbed714	0:d616ece2d859	478	#if TCP_OVERSIZE_DBGCHECK
mbed714	0:d616ece2d859	479	last_unsent->oversize_left = oversize;
mbed714	0:d616ece2d859	480	#endif /* TCP_OVERSIZE_DBGCHECK */
mbed714	0:d616ece2d859	481	TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
mbed714	0:d616ece2d859	482	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	483	concat_chksummed += seglen;
mbed714	0:d616ece2d859	484	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	485	} else {
mbed714	0:d616ece2d859	486	/* Data is not copied */
mbed714	0:d616ece2d859	487	if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
mbed714	0:d616ece2d859	488	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
mbed714	0:d616ece2d859	489	("tcp_write: could not allocate memory for zero-copy pbuf\n"));
mbed714	0:d616ece2d859	490	goto memerr;
mbed714	0:d616ece2d859	491	}
mbed714	0:d616ece2d859	492	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	493	/* calculate the checksum of nocopy-data */
mbed714	0:d616ece2d859	494	tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
mbed714	0:d616ece2d859	495	&concat_chksum, &concat_chksum_swapped);
mbed714	0:d616ece2d859	496	concat_chksummed += seglen;
mbed714	0:d616ece2d859	497	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	498	/* reference the non-volatile payload data */
mbed714	0:d616ece2d859	499	concat_p->payload = (u8_t*)arg + pos;
mbed714	0:d616ece2d859	500	}
mbed714	0:d616ece2d859	501
mbed714	0:d616ece2d859	502	pos += seglen;
mbed714	0:d616ece2d859	503	queuelen += pbuf_clen(concat_p);
mbed714	0:d616ece2d859	504	}
mbed714	0:d616ece2d859	505	} else {
mbed714	0:d616ece2d859	506	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	507	LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
mbed714	0:d616ece2d859	508	pcb->unsent_oversize == 0);
mbed714	0:d616ece2d859	509	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	510	}
mbed714	0:d616ece2d859	511
mbed714	0:d616ece2d859	512	/*
mbed714	0:d616ece2d859	513	* Phase 3: Create new segments.
mbed714	0:d616ece2d859	514	*
mbed714	0:d616ece2d859	515	* The new segments are chained together in the local 'queue'
mbed714	0:d616ece2d859	516	* variable, ready to be appended to pcb->unsent.
mbed714	0:d616ece2d859	517	*/
mbed714	0:d616ece2d859	518	while (pos < len) {
mbed714	0:d616ece2d859	519	struct pbuf *p;
mbed714	0:d616ece2d859	520	u16_t left = len - pos;
mbed714	0:d616ece2d859	521	u16_t max_len = pcb->mss - optlen;
mbed714	0:d616ece2d859	522	u16_t seglen = left > max_len ? max_len : left;
mbed714	0:d616ece2d859	523	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	524	u16_t chksum = 0;
mbed714	0:d616ece2d859	525	u8_t chksum_swapped = 0;
mbed714	0:d616ece2d859	526	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	527
mbed714	0:d616ece2d859	528	if (apiflags & TCP_WRITE_FLAG_COPY) {
mbed714	0:d616ece2d859	529	/* If copy is set, memory should be allocated and data copied
mbed714	0:d616ece2d859	530	* into pbuf */
mbed714	0:d616ece2d859	531	if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, pcb->mss, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
mbed714	0:d616ece2d859	532	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
mbed714	0:d616ece2d859	533	goto memerr;
mbed714	0:d616ece2d859	534	}
mbed714	0:d616ece2d859	535	LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
mbed714	0:d616ece2d859	536	(p->len >= seglen));
mbed714	0:d616ece2d859	537	TCP_DATA_COPY2((char )p->payload + optlen, (u8_t)arg + pos, seglen, &chksum, &chksum_swapped);
mbed714	0:d616ece2d859	538	} else {
mbed714	0:d616ece2d859	539	/* Copy is not set: First allocate a pbuf for holding the data.
mbed714	0:d616ece2d859	540	* Since the referenced data is available at least until it is
mbed714	0:d616ece2d859	541	* sent out on the link (as it has to be ACKed by the remote
mbed714	0:d616ece2d859	542	* party) we can safely use PBUF_ROM instead of PBUF_REF here.
mbed714	0:d616ece2d859	543	*/
mbed714	0:d616ece2d859	544	struct pbuf *p2;
mbed714	0:d616ece2d859	545	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	546	LWIP_ASSERT("oversize == 0", oversize == 0);
mbed714	0:d616ece2d859	547	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	548	if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
mbed714	0:d616ece2d859	549	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
mbed714	0:d616ece2d859	550	goto memerr;
mbed714	0:d616ece2d859	551	}
mbed714	0:d616ece2d859	552	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	553	/* calculate the checksum of nocopy-data */
mbed714	0:d616ece2d859	554	chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
mbed714	0:d616ece2d859	555	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	556	/* reference the non-volatile payload data */
mbed714	0:d616ece2d859	557	p2->payload = (u8_t*)arg + pos;
mbed714	0:d616ece2d859	558
mbed714	0:d616ece2d859	559	/* Second, allocate a pbuf for the headers. */
mbed714	0:d616ece2d859	560	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
mbed714	0:d616ece2d859	561	/* If allocation fails, we have to deallocate the data pbuf as
mbed714	0:d616ece2d859	562	* well. */
mbed714	0:d616ece2d859	563	pbuf_free(p2);
mbed714	0:d616ece2d859	564	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for header pbuf\n"));
mbed714	0:d616ece2d859	565	goto memerr;
mbed714	0:d616ece2d859	566	}
mbed714	0:d616ece2d859	567	/* Concatenate the headers and data pbufs together. */
mbed714	0:d616ece2d859	568	pbuf_cat(p/header/, p2/data/);
mbed714	0:d616ece2d859	569	}
mbed714	0:d616ece2d859	570
mbed714	0:d616ece2d859	571	queuelen += pbuf_clen(p);
mbed714	0:d616ece2d859	572
mbed714	0:d616ece2d859	573	/* Now that there are more segments queued, we check again if the
mbed714	0:d616ece2d859	574	* length of the queue exceeds the configured maximum or
mbed714	0:d616ece2d859	575	* overflows. */
mbed714	0:d616ece2d859	576	if ((queuelen > TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
mbed714	0:d616ece2d859	577	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
mbed714	0:d616ece2d859	578	pbuf_free(p);
mbed714	0:d616ece2d859	579	goto memerr;
mbed714	0:d616ece2d859	580	}
mbed714	0:d616ece2d859	581
mbed714	0:d616ece2d859	582	if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
mbed714	0:d616ece2d859	583	goto memerr;
mbed714	0:d616ece2d859	584	}
mbed714	0:d616ece2d859	585	#if TCP_OVERSIZE_DBGCHECK
mbed714	0:d616ece2d859	586	seg->oversize_left = oversize;
mbed714	0:d616ece2d859	587	#endif /* TCP_OVERSIZE_DBGCHECK */
mbed714	0:d616ece2d859	588	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	589	seg->chksum = chksum;
mbed714	0:d616ece2d859	590	seg->chksum_swapped = chksum_swapped;
mbed714	0:d616ece2d859	591	seg->flags \|= TF_SEG_DATA_CHECKSUMMED;
mbed714	0:d616ece2d859	592	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	593	/* Fix dataptr for the nocopy case */
mbed714	0:d616ece2d859	594	if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
mbed714	0:d616ece2d859	595	seg->dataptr = (u8_t*)arg + pos;
mbed714	0:d616ece2d859	596	}
mbed714	0:d616ece2d859	597
mbed714	0:d616ece2d859	598	/* first segment of to-be-queued data? */
mbed714	0:d616ece2d859	599	if (queue == NULL) {
mbed714	0:d616ece2d859	600	queue = seg;
mbed714	0:d616ece2d859	601	} else {
mbed714	0:d616ece2d859	602	/* Attach the segment to the end of the queued segments */
mbed714	0:d616ece2d859	603	LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
mbed714	0:d616ece2d859	604	prev_seg->next = seg;
mbed714	0:d616ece2d859	605	}
mbed714	0:d616ece2d859	606	/* remember last segment of to-be-queued data for next iteration */
mbed714	0:d616ece2d859	607	prev_seg = seg;
mbed714	0:d616ece2d859	608
mbed714	0:d616ece2d859	609	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
mbed714	0:d616ece2d859	610	ntohl(seg->tcphdr->seqno),
mbed714	0:d616ece2d859	611	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
mbed714	0:d616ece2d859	612
mbed714	0:d616ece2d859	613	pos += seglen;
mbed714	0:d616ece2d859	614	}
mbed714	0:d616ece2d859	615
mbed714	0:d616ece2d859	616	/*
mbed714	0:d616ece2d859	617	* All three segmentation phases were successful. We can commit the
mbed714	0:d616ece2d859	618	* transaction.
mbed714	0:d616ece2d859	619	*/
mbed714	0:d616ece2d859	620
mbed714	0:d616ece2d859	621	/*
mbed714	0:d616ece2d859	622	* Phase 1: If data has been added to the preallocated tail of
mbed714	0:d616ece2d859	623	* last_unsent, we update the length fields of the pbuf chain.
mbed714	0:d616ece2d859	624	*/
mbed714	0:d616ece2d859	625	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	626	if (oversize_used > 0) {
mbed714	0:d616ece2d859	627	struct pbuf *p;
mbed714	0:d616ece2d859	628	/* Bump tot_len of whole chain, len of tail */
mbed714	0:d616ece2d859	629	for (p = last_unsent->p; p; p = p->next) {
mbed714	0:d616ece2d859	630	p->tot_len += oversize_used;
mbed714	0:d616ece2d859	631	if (p->next == NULL) {
mbed714	0:d616ece2d859	632	TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
mbed714	0:d616ece2d859	633	p->len += oversize_used;
mbed714	0:d616ece2d859	634	}
mbed714	0:d616ece2d859	635	}
mbed714	0:d616ece2d859	636	last_unsent->len += oversize_used;
mbed714	0:d616ece2d859	637	#if TCP_OVERSIZE_DBGCHECK
mbed714	0:d616ece2d859	638	last_unsent->oversize_left -= oversize_used;
mbed714	0:d616ece2d859	639	#endif /* TCP_OVERSIZE_DBGCHECK */
mbed714	0:d616ece2d859	640	}
mbed714	0:d616ece2d859	641	pcb->unsent_oversize = oversize;
mbed714	0:d616ece2d859	642	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	643
mbed714	0:d616ece2d859	644	/*
mbed714	0:d616ece2d859	645	* Phase 2: concat_p can be concatenated onto last_unsent->p
mbed714	0:d616ece2d859	646	*/
mbed714	0:d616ece2d859	647	if (concat_p != NULL) {
mbed714	0:d616ece2d859	648	LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
mbed714	0:d616ece2d859	649	(last_unsent != NULL));
mbed714	0:d616ece2d859	650	pbuf_cat(last_unsent->p, concat_p);
mbed714	0:d616ece2d859	651	last_unsent->len += concat_p->tot_len;
mbed714	0:d616ece2d859	652	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	653	if (concat_chksummed) {
mbed714	0:d616ece2d859	654	tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
mbed714	0:d616ece2d859	655	&last_unsent->chksum_swapped);
mbed714	0:d616ece2d859	656	last_unsent->flags \|= TF_SEG_DATA_CHECKSUMMED;
mbed714	0:d616ece2d859	657	}
mbed714	0:d616ece2d859	658	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	659	}
mbed714	0:d616ece2d859	660
mbed714	0:d616ece2d859	661	/*
mbed714	0:d616ece2d859	662	* Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
mbed714	0:d616ece2d859	663	* is harmless
mbed714	0:d616ece2d859	664	*/
mbed714	0:d616ece2d859	665	if (last_unsent == NULL) {
mbed714	0:d616ece2d859	666	pcb->unsent = queue;
mbed714	0:d616ece2d859	667	} else {
mbed714	0:d616ece2d859	668	last_unsent->next = queue;
mbed714	0:d616ece2d859	669	}
mbed714	0:d616ece2d859	670
mbed714	0:d616ece2d859	671	/*
mbed714	0:d616ece2d859	672	* Finally update the pcb state.
mbed714	0:d616ece2d859	673	*/
mbed714	0:d616ece2d859	674	pcb->snd_lbb += len;
mbed714	0:d616ece2d859	675	pcb->snd_buf -= len;
mbed714	0:d616ece2d859	676	pcb->snd_queuelen = queuelen;
mbed714	0:d616ece2d859	677
mbed714	0:d616ece2d859	678	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
mbed714	0:d616ece2d859	679	pcb->snd_queuelen));
mbed714	0:d616ece2d859	680	if (pcb->snd_queuelen != 0) {
mbed714	0:d616ece2d859	681	LWIP_ASSERT("tcp_write: valid queue length",
mbed714	0:d616ece2d859	682	pcb->unacked != NULL \|\| pcb->unsent != NULL);
mbed714	0:d616ece2d859	683	}
mbed714	0:d616ece2d859	684
mbed714	0:d616ece2d859	685	/* Set the PSH flag in the last segment that we enqueued. */
mbed714	0:d616ece2d859	686	if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
mbed714	0:d616ece2d859	687	TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
mbed714	0:d616ece2d859	688	}
mbed714	0:d616ece2d859	689
mbed714	0:d616ece2d859	690	return ERR_OK;
mbed714	0:d616ece2d859	691	memerr:
mbed714	0:d616ece2d859	692	pcb->flags \|= TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	693	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	694
mbed714	0:d616ece2d859	695	if (concat_p != NULL) {
mbed714	0:d616ece2d859	696	pbuf_free(concat_p);
mbed714	0:d616ece2d859	697	}
mbed714	0:d616ece2d859	698	if (queue != NULL) {
mbed714	0:d616ece2d859	699	tcp_segs_free(queue);
mbed714	0:d616ece2d859	700	}
mbed714	0:d616ece2d859	701	if (pcb->snd_queuelen != 0) {
mbed714	0:d616ece2d859	702	LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL \|\|
mbed714	0:d616ece2d859	703	pcb->unsent != NULL);
mbed714	0:d616ece2d859	704	}
mbed714	0:d616ece2d859	705	LWIP_DEBUGF(TCP_QLEN_DEBUG \| LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
mbed714	0:d616ece2d859	706	return ERR_MEM;
mbed714	0:d616ece2d859	707	}
mbed714	0:d616ece2d859	708
mbed714	0:d616ece2d859	709	/**
mbed714	0:d616ece2d859	710	* Enqueue TCP options for transmission.
mbed714	0:d616ece2d859	711	*
mbed714	0:d616ece2d859	712	* Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
mbed714	0:d616ece2d859	713	*
mbed714	0:d616ece2d859	714	* @param pcb Protocol control block for the TCP connection.
mbed714	0:d616ece2d859	715	* @param flags TCP header flags to set in the outgoing segment.
mbed714	0:d616ece2d859	716	* @param optdata pointer to TCP options, or NULL.
mbed714	0:d616ece2d859	717	* @param optlen length of TCP options in bytes.
mbed714	0:d616ece2d859	718	*/
mbed714	0:d616ece2d859	719	err_t
mbed714	0:d616ece2d859	720	tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
mbed714	0:d616ece2d859	721	{
mbed714	0:d616ece2d859	722	struct pbuf *p;
mbed714	0:d616ece2d859	723	struct tcp_seg *seg;
mbed714	0:d616ece2d859	724	u8_t optflags = 0;
mbed714	0:d616ece2d859	725	u8_t optlen = 0;
mbed714	0:d616ece2d859	726
mbed714	0:d616ece2d859	727	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	728
mbed714	0:d616ece2d859	729	LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
mbed714	0:d616ece2d859	730	(flags & (TCP_SYN \| TCP_FIN)) != 0);
mbed714	0:d616ece2d859	731
mbed714	0:d616ece2d859	732	/* check for configured max queuelen and possible overflow */
mbed714	0:d616ece2d859	733	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
mbed714	0:d616ece2d859	734	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
mbed714	0:d616ece2d859	735	pcb->snd_queuelen, TCP_SND_QUEUELEN));
mbed714	0:d616ece2d859	736	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	737	pcb->flags \|= TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	738	return ERR_MEM;
mbed714	0:d616ece2d859	739	}
mbed714	0:d616ece2d859	740
mbed714	0:d616ece2d859	741	if (flags & TCP_SYN) {
mbed714	0:d616ece2d859	742	optflags = TF_SEG_OPTS_MSS;
mbed714	0:d616ece2d859	743	}
mbed714	0:d616ece2d859	744	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	745	if ((pcb->flags & TF_TIMESTAMP)) {
mbed714	0:d616ece2d859	746	optflags \|= TF_SEG_OPTS_TS;
mbed714	0:d616ece2d859	747	}
mbed714	0:d616ece2d859	748	#endif /* LWIP_TCP_TIMESTAMPS */
mbed714	0:d616ece2d859	749	optlen = LWIP_TCP_OPT_LENGTH(optflags);
mbed714	0:d616ece2d859	750
mbed714	0:d616ece2d859	751	/* tcp_enqueue_flags is always called with either SYN or FIN in flags.
mbed714	0:d616ece2d859	752	* We need one available snd_buf byte to do that.
mbed714	0:d616ece2d859	753	* This means we can't send FIN while snd_buf==0. A better fix would be to
mbed714	0:d616ece2d859	754	* not include SYN and FIN sequence numbers in the snd_buf count. */
mbed714	0:d616ece2d859	755	if (pcb->snd_buf == 0) {
mbed714	0:d616ece2d859	756	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: no send buffer available\n"));
mbed714	0:d616ece2d859	757	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	758	return ERR_MEM;
mbed714	0:d616ece2d859	759	}
mbed714	0:d616ece2d859	760
mbed714	0:d616ece2d859	761	/* Allocate pbuf with room for TCP header + options */
mbed714	0:d616ece2d859	762	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
mbed714	0:d616ece2d859	763	pcb->flags \|= TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	764	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	765	return ERR_MEM;
mbed714	0:d616ece2d859	766	}
mbed714	0:d616ece2d859	767	LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
mbed714	0:d616ece2d859	768	(p->len >= optlen));
mbed714	0:d616ece2d859	769
mbed714	0:d616ece2d859	770	/* Allocate memory for tcp_seg, and fill in fields. */
mbed714	0:d616ece2d859	771	if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
mbed714	0:d616ece2d859	772	pcb->flags \|= TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	773	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	774	return ERR_MEM;
mbed714	0:d616ece2d859	775	}
mbed714	0:d616ece2d859	776	LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
mbed714	0:d616ece2d859	777
mbed714	0:d616ece2d859	778	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE,
mbed714	0:d616ece2d859	779	("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
mbed714	0:d616ece2d859	780	ntohl(seg->tcphdr->seqno),
mbed714	0:d616ece2d859	781	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
mbed714	0:d616ece2d859	782	(u16_t)flags));
mbed714	0:d616ece2d859	783
mbed714	0:d616ece2d859	784	/* Now append seg to pcb->unsent queue */
mbed714	0:d616ece2d859	785	if (pcb->unsent == NULL) {
mbed714	0:d616ece2d859	786	pcb->unsent = seg;
mbed714	0:d616ece2d859	787	} else {
mbed714	0:d616ece2d859	788	struct tcp_seg *useg;
mbed714	0:d616ece2d859	789	for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
mbed714	0:d616ece2d859	790	useg->next = seg;
mbed714	0:d616ece2d859	791	}
mbed714	0:d616ece2d859	792	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	793	/* The new unsent tail has no space */
mbed714	0:d616ece2d859	794	pcb->unsent_oversize = 0;
mbed714	0:d616ece2d859	795	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	796
mbed714	0:d616ece2d859	797	/* SYN and FIN bump the sequence number */
mbed714	0:d616ece2d859	798	if ((flags & TCP_SYN) \|\| (flags & TCP_FIN)) {
mbed714	0:d616ece2d859	799	pcb->snd_lbb++;
mbed714	0:d616ece2d859	800	/* optlen does not influence snd_buf */
mbed714	0:d616ece2d859	801	pcb->snd_buf--;
mbed714	0:d616ece2d859	802	}
mbed714	0:d616ece2d859	803	if (flags & TCP_FIN) {
mbed714	0:d616ece2d859	804	pcb->flags \|= TF_FIN;
mbed714	0:d616ece2d859	805	}
mbed714	0:d616ece2d859	806
mbed714	0:d616ece2d859	807	/* update number of segments on the queues */
mbed714	0:d616ece2d859	808	pcb->snd_queuelen += pbuf_clen(seg->p);
mbed714	0:d616ece2d859	809	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
mbed714	0:d616ece2d859	810	if (pcb->snd_queuelen != 0) {
mbed714	0:d616ece2d859	811	LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
mbed714	0:d616ece2d859	812	pcb->unacked != NULL \|\| pcb->unsent != NULL);
mbed714	0:d616ece2d859	813	}
mbed714	0:d616ece2d859	814
mbed714	0:d616ece2d859	815	return ERR_OK;
mbed714	0:d616ece2d859	816	}
mbed714	0:d616ece2d859	817
mbed714	0:d616ece2d859	818
mbed714	0:d616ece2d859	819	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	820	/* Build a timestamp option (12 bytes long) at the specified options pointer)
mbed714	0:d616ece2d859	821	*
mbed714	0:d616ece2d859	822	* @param pcb tcp_pcb
mbed714	0:d616ece2d859	823	* @param opts option pointer where to store the timestamp option
mbed714	0:d616ece2d859	824	*/
mbed714	0:d616ece2d859	825	static void
mbed714	0:d616ece2d859	826	tcp_build_timestamp_option(struct tcp_pcb pcb, u32_t opts)
mbed714	0:d616ece2d859	827	{
mbed714	0:d616ece2d859	828	/* Pad with two NOP options to make everything nicely aligned */
mbed714	0:d616ece2d859	829	opts[0] = PP_HTONL(0x0101080A);
mbed714	0:d616ece2d859	830	opts[1] = htonl(sys_now());
mbed714	0:d616ece2d859	831	opts[2] = htonl(pcb->ts_recent);
mbed714	0:d616ece2d859	832	}
mbed714	0:d616ece2d859	833	#endif
mbed714	0:d616ece2d859	834
mbed714	0:d616ece2d859	835	/** Send an ACK without data.
mbed714	0:d616ece2d859	836	*
mbed714	0:d616ece2d859	837	* @param pcb Protocol control block for the TCP connection to send the ACK
mbed714	0:d616ece2d859	838	*/
mbed714	0:d616ece2d859	839	err_t
mbed714	0:d616ece2d859	840	tcp_send_empty_ack(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	841	{
mbed714	0:d616ece2d859	842	struct pbuf *p;
mbed714	0:d616ece2d859	843	struct tcp_hdr *tcphdr;
mbed714	0:d616ece2d859	844	u8_t optlen = 0;
mbed714	0:d616ece2d859	845
mbed714	0:d616ece2d859	846	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	847	if (pcb->flags & TF_TIMESTAMP) {
mbed714	0:d616ece2d859	848	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
mbed714	0:d616ece2d859	849	}
mbed714	0:d616ece2d859	850	#endif
mbed714	0:d616ece2d859	851
mbed714	0:d616ece2d859	852	p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
mbed714	0:d616ece2d859	853	if (p == NULL) {
mbed714	0:d616ece2d859	854	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
mbed714	0:d616ece2d859	855	return ERR_BUF;
mbed714	0:d616ece2d859	856	}
mbed714	0:d616ece2d859	857	tcphdr = (struct tcp_hdr *)p->payload;
mbed714	0:d616ece2d859	858	LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
mbed714	0:d616ece2d859	859	("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
mbed714	0:d616ece2d859	860	/* remove ACK flags from the PCB, as we send an empty ACK now */
mbed714	0:d616ece2d859	861	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
mbed714	0:d616ece2d859	862
mbed714	0:d616ece2d859	863	/* NB. MSS option is only sent on SYNs, so ignore it here */
mbed714	0:d616ece2d859	864	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	865	pcb->ts_lastacksent = pcb->rcv_nxt;
mbed714	0:d616ece2d859	866
mbed714	0:d616ece2d859	867	if (pcb->flags & TF_TIMESTAMP) {
mbed714	0:d616ece2d859	868	tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
mbed714	0:d616ece2d859	869	}
mbed714	0:d616ece2d859	870	#endif
mbed714	0:d616ece2d859	871
mbed714	0:d616ece2d859	872	#if CHECKSUM_GEN_TCP
mbed714	0:d616ece2d859	873	tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
mbed714	0:d616ece2d859	874	IP_PROTO_TCP, p->tot_len);
mbed714	0:d616ece2d859	875	#endif
mbed714	0:d616ece2d859	876	#if LWIP_NETIF_HWADDRHINT
mbed714	0:d616ece2d859	877	ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
mbed714	0:d616ece2d859	878	IP_PROTO_TCP, &(pcb->addr_hint));
mbed714	0:d616ece2d859	879	#else /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	880	ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
mbed714	0:d616ece2d859	881	IP_PROTO_TCP);
mbed714	0:d616ece2d859	882	#endif /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	883	pbuf_free(p);
mbed714	0:d616ece2d859	884
mbed714	0:d616ece2d859	885	return ERR_OK;
mbed714	0:d616ece2d859	886	}
mbed714	0:d616ece2d859	887
mbed714	0:d616ece2d859	888	/**
mbed714	0:d616ece2d859	889	* Find out what we can send and send it
mbed714	0:d616ece2d859	890	*
mbed714	0:d616ece2d859	891	* @param pcb Protocol control block for the TCP connection to send data
mbed714	0:d616ece2d859	892	* @return ERR_OK if data has been sent or nothing to send
mbed714	0:d616ece2d859	893	* another err_t on error
mbed714	0:d616ece2d859	894	*/
mbed714	0:d616ece2d859	895	err_t
mbed714	0:d616ece2d859	896	tcp_output(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	897	{
mbed714	0:d616ece2d859	898	struct tcp_seg seg, useg;
mbed714	0:d616ece2d859	899	u32_t wnd, snd_nxt;
mbed714	0:d616ece2d859	900	#if TCP_CWND_DEBUG
mbed714	0:d616ece2d859	901	s16_t i = 0;
mbed714	0:d616ece2d859	902	#endif /* TCP_CWND_DEBUG */
mbed714	0:d616ece2d859	903
mbed714	0:d616ece2d859	904	/* First, check if we are invoked by the TCP input processing
mbed714	0:d616ece2d859	905	code. If so, we do not output anything. Instead, we rely on the
mbed714	0:d616ece2d859	906	input processing code to call us when input processing is done
mbed714	0:d616ece2d859	907	with. */
mbed714	0:d616ece2d859	908	if (tcp_input_pcb == pcb) {
mbed714	0:d616ece2d859	909	return ERR_OK;
mbed714	0:d616ece2d859	910	}
mbed714	0:d616ece2d859	911
mbed714	0:d616ece2d859	912	wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
mbed714	0:d616ece2d859	913
mbed714	0:d616ece2d859	914	seg = pcb->unsent;
mbed714	0:d616ece2d859	915
mbed714	0:d616ece2d859	916	/* If the TF_ACK_NOW flag is set and no data will be sent (either
mbed714	0:d616ece2d859	917	* because the ->unsent queue is empty or because the window does
mbed714	0:d616ece2d859	918	* not allow it), construct an empty ACK segment and send it.
mbed714	0:d616ece2d859	919	*
mbed714	0:d616ece2d859	920	* If data is to be sent, we will just piggyback the ACK (see below).
mbed714	0:d616ece2d859	921	*/
mbed714	0:d616ece2d859	922	if (pcb->flags & TF_ACK_NOW &&
mbed714	0:d616ece2d859	923	(seg == NULL \|\|
mbed714	0:d616ece2d859	924	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
mbed714	0:d616ece2d859	925	return tcp_send_empty_ack(pcb);
mbed714	0:d616ece2d859	926	}
mbed714	0:d616ece2d859	927
mbed714	0:d616ece2d859	928	/* useg should point to last segment on unacked queue */
mbed714	0:d616ece2d859	929	useg = pcb->unacked;
mbed714	0:d616ece2d859	930	if (useg != NULL) {
mbed714	0:d616ece2d859	931	for (; useg->next != NULL; useg = useg->next);
mbed714	0:d616ece2d859	932	}
mbed714	0:d616ece2d859	933
mbed714	0:d616ece2d859	934	#if TCP_OUTPUT_DEBUG
mbed714	0:d616ece2d859	935	if (seg == NULL) {
mbed714	0:d616ece2d859	936	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
mbed714	0:d616ece2d859	937	(void*)pcb->unsent));
mbed714	0:d616ece2d859	938	}
mbed714	0:d616ece2d859	939	#endif /* TCP_OUTPUT_DEBUG */
mbed714	0:d616ece2d859	940	#if TCP_CWND_DEBUG
mbed714	0:d616ece2d859	941	if (seg == NULL) {
mbed714	0:d616ece2d859	942	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
mbed714	0:d616ece2d859	943	", cwnd %"U16_F", wnd %"U32_F
mbed714	0:d616ece2d859	944	", seg == NULL, ack %"U32_F"\n",
mbed714	0:d616ece2d859	945	pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
mbed714	0:d616ece2d859	946	} else {
mbed714	0:d616ece2d859	947	LWIP_DEBUGF(TCP_CWND_DEBUG,
mbed714	0:d616ece2d859	948	("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
mbed714	0:d616ece2d859	949	", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
mbed714	0:d616ece2d859	950	pcb->snd_wnd, pcb->cwnd, wnd,
mbed714	0:d616ece2d859	951	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
mbed714	0:d616ece2d859	952	ntohl(seg->tcphdr->seqno), pcb->lastack));
mbed714	0:d616ece2d859	953	}
mbed714	0:d616ece2d859	954	#endif /* TCP_CWND_DEBUG */
mbed714	0:d616ece2d859	955	/* data available and window allows it to be sent? */
mbed714	0:d616ece2d859	956	while (seg != NULL &&
mbed714	0:d616ece2d859	957	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
mbed714	0:d616ece2d859	958	LWIP_ASSERT("RST not expected here!",
mbed714	0:d616ece2d859	959	(TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
mbed714	0:d616ece2d859	960	/* Stop sending if the nagle algorithm would prevent it
mbed714	0:d616ece2d859	961	* Don't stop:
mbed714	0:d616ece2d859	962	* - if tcp_write had a memory error before (prevent delayed ACK timeout) or
mbed714	0:d616ece2d859	963	* - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
mbed714	0:d616ece2d859	964	* either seg->next != NULL or pcb->unacked == NULL;
mbed714	0:d616ece2d859	965	* RST is no sent using tcp_write/tcp_output.
mbed714	0:d616ece2d859	966	*/
mbed714	0:d616ece2d859	967	if((tcp_do_output_nagle(pcb) == 0) &&
mbed714	0:d616ece2d859	968	((pcb->flags & (TF_NAGLEMEMERR \| TF_FIN)) == 0)){
mbed714	0:d616ece2d859	969	break;
mbed714	0:d616ece2d859	970	}
mbed714	0:d616ece2d859	971	#if TCP_CWND_DEBUG
mbed714	0:d616ece2d859	972	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",
mbed714	0:d616ece2d859	973	pcb->snd_wnd, pcb->cwnd, wnd,
mbed714	0:d616ece2d859	974	ntohl(seg->tcphdr->seqno) + seg->len -
mbed714	0:d616ece2d859	975	pcb->lastack,
mbed714	0:d616ece2d859	976	ntohl(seg->tcphdr->seqno), pcb->lastack, i));
mbed714	0:d616ece2d859	977	++i;
mbed714	0:d616ece2d859	978	#endif /* TCP_CWND_DEBUG */
mbed714	0:d616ece2d859	979
mbed714	0:d616ece2d859	980	pcb->unsent = seg->next;
mbed714	0:d616ece2d859	981
mbed714	0:d616ece2d859	982	if (pcb->state != SYN_SENT) {
mbed714	0:d616ece2d859	983	TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
mbed714	0:d616ece2d859	984	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
mbed714	0:d616ece2d859	985	}
mbed714	0:d616ece2d859	986
mbed714	0:d616ece2d859	987	tcp_output_segment(seg, pcb);
mbed714	0:d616ece2d859	988
mbed714	0:d616ece2d859	989	snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
mbed714	0:d616ece2d859	990
mbed714	0:d616ece2d859	991	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: pcb->snd_nxt was %"U32_F" seqno=%"U32_F" len=%"U32_F" new snd_nxt=%"U32_F"\n", //DG
mbed714	0:d616ece2d859	992	pcb->snd_nxt, ntohl(seg->tcphdr->seqno), TCP_TCPLEN(seg), snd_nxt));
mbed714	0:d616ece2d859	993
mbed714	0:d616ece2d859	994	if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
mbed714	0:d616ece2d859	995	pcb->snd_nxt = snd_nxt;
mbed714	0:d616ece2d859	996	}
mbed714	0:d616ece2d859	997	/* put segment on unacknowledged list if length > 0 */
mbed714	0:d616ece2d859	998	if (TCP_TCPLEN(seg) > 0) {
mbed714	0:d616ece2d859	999	seg->next = NULL;
mbed714	0:d616ece2d859	1000	/* unacked list is empty? */
mbed714	0:d616ece2d859	1001	if (pcb->unacked == NULL) {
mbed714	0:d616ece2d859	1002	pcb->unacked = seg;
mbed714	0:d616ece2d859	1003	useg = seg;
mbed714	0:d616ece2d859	1004	/* unacked list is not empty? */
mbed714	0:d616ece2d859	1005	} else {
mbed714	0:d616ece2d859	1006	/* In the case of fast retransmit, the packet should not go to the tail
mbed714	0:d616ece2d859	1007	* of the unacked queue, but rather somewhere before it. We need to check for
mbed714	0:d616ece2d859	1008	* this case. -STJ Jul 27, 2004 */
mbed714	0:d616ece2d859	1009	if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
mbed714	0:d616ece2d859	1010	/* add segment to before tail of unacked list, keeping the list sorted */
mbed714	0:d616ece2d859	1011	struct tcp_seg **cur_seg = &(pcb->unacked);
mbed714	0:d616ece2d859	1012	while (*cur_seg &&
mbed714	0:d616ece2d859	1013	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
mbed714	0:d616ece2d859	1014	cur_seg = &((*cur_seg)->next );
mbed714	0:d616ece2d859	1015	}
mbed714	0:d616ece2d859	1016	seg->next = (*cur_seg);
mbed714	0:d616ece2d859	1017	(*cur_seg) = seg;
mbed714	0:d616ece2d859	1018	} else {
mbed714	0:d616ece2d859	1019	/* add segment to tail of unacked list */
mbed714	0:d616ece2d859	1020	useg->next = seg;
mbed714	0:d616ece2d859	1021	useg = useg->next;
mbed714	0:d616ece2d859	1022	}
mbed714	0:d616ece2d859	1023	}
mbed714	0:d616ece2d859	1024	/* do not queue empty segments on the unacked list */
mbed714	0:d616ece2d859	1025	} else {
mbed714	0:d616ece2d859	1026	tcp_seg_free(seg);
mbed714	0:d616ece2d859	1027	}
mbed714	0:d616ece2d859	1028	seg = pcb->unsent;
mbed714	0:d616ece2d859	1029	}
mbed714	0:d616ece2d859	1030	#if TCP_OVERSIZE
mbed714	0:d616ece2d859	1031	if (pcb->unsent == NULL) {
mbed714	0:d616ece2d859	1032	/* last unsent has been removed, reset unsent_oversize */
mbed714	0:d616ece2d859	1033	pcb->unsent_oversize = 0;
mbed714	0:d616ece2d859	1034	}
mbed714	0:d616ece2d859	1035	#endif /* TCP_OVERSIZE */
mbed714	0:d616ece2d859	1036
mbed714	0:d616ece2d859	1037	if (seg != NULL && pcb->persist_backoff == 0 &&
mbed714	0:d616ece2d859	1038	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) {
mbed714	0:d616ece2d859	1039	/* prepare for persist timer */
mbed714	0:d616ece2d859	1040	pcb->persist_cnt = 0;
mbed714	0:d616ece2d859	1041	pcb->persist_backoff = 1;
mbed714	0:d616ece2d859	1042	}
mbed714	0:d616ece2d859	1043
mbed714	0:d616ece2d859	1044	pcb->flags &= ~TF_NAGLEMEMERR;
mbed714	0:d616ece2d859	1045	return ERR_OK;
mbed714	0:d616ece2d859	1046	}
mbed714	0:d616ece2d859	1047
mbed714	0:d616ece2d859	1048	/**
mbed714	0:d616ece2d859	1049	* Called by tcp_output() to actually send a TCP segment over IP.
mbed714	0:d616ece2d859	1050	*
mbed714	0:d616ece2d859	1051	* @param seg the tcp_seg to send
mbed714	0:d616ece2d859	1052	* @param pcb the tcp_pcb for the TCP connection used to send the segment
mbed714	0:d616ece2d859	1053	*/
mbed714	0:d616ece2d859	1054	static void
mbed714	0:d616ece2d859	1055	tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb)
mbed714	0:d616ece2d859	1056	{
mbed714	0:d616ece2d859	1057	u16_t len;
mbed714	0:d616ece2d859	1058	struct netif *netif;
mbed714	0:d616ece2d859	1059	u32_t *opts;
mbed714	0:d616ece2d859	1060
mbed714	0:d616ece2d859	1061	/** @bug Exclude retransmitted segments from this count. */
mbed714	0:d616ece2d859	1062	snmp_inc_tcpoutsegs();
mbed714	0:d616ece2d859	1063
mbed714	0:d616ece2d859	1064	/* The TCP header has already been constructed, but the ackno and
mbed714	0:d616ece2d859	1065	wnd fields remain. */
mbed714	0:d616ece2d859	1066	seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
mbed714	0:d616ece2d859	1067
mbed714	0:d616ece2d859	1068	/* advertise our receive window size in this TCP segment */
mbed714	0:d616ece2d859	1069	seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
mbed714	0:d616ece2d859	1070
mbed714	0:d616ece2d859	1071	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
mbed714	0:d616ece2d859	1072
mbed714	0:d616ece2d859	1073	/* Add any requested options. NB MSS option is only set on SYN
mbed714	0:d616ece2d859	1074	packets, so ignore it here */
mbed714	0:d616ece2d859	1075	LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
mbed714	0:d616ece2d859	1076	opts = (u32_t )(void )(seg->tcphdr + 1);
mbed714	0:d616ece2d859	1077	if (seg->flags & TF_SEG_OPTS_MSS) {
mbed714	0:d616ece2d859	1078	TCP_BUILD_MSS_OPTION(*opts);
mbed714	0:d616ece2d859	1079	opts += 1;
mbed714	0:d616ece2d859	1080	}
mbed714	0:d616ece2d859	1081	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	1082	pcb->ts_lastacksent = pcb->rcv_nxt;
mbed714	0:d616ece2d859	1083
mbed714	0:d616ece2d859	1084	if (seg->flags & TF_SEG_OPTS_TS) {
mbed714	0:d616ece2d859	1085	tcp_build_timestamp_option(pcb, opts);
mbed714	0:d616ece2d859	1086	opts += 3;
mbed714	0:d616ece2d859	1087	}
mbed714	0:d616ece2d859	1088	#endif
mbed714	0:d616ece2d859	1089
mbed714	0:d616ece2d859	1090	/* If we don't have a local IP address, we get one by
mbed714	0:d616ece2d859	1091	calling ip_route(). */
mbed714	0:d616ece2d859	1092	if (ip_addr_isany(&(pcb->local_ip))) {
mbed714	0:d616ece2d859	1093	netif = ip_route(&(pcb->remote_ip));
mbed714	0:d616ece2d859	1094	if (netif == NULL) {
mbed714	0:d616ece2d859	1095	return;
mbed714	0:d616ece2d859	1096	}
mbed714	0:d616ece2d859	1097	ip_addr_copy(pcb->local_ip, netif->ip_addr);
mbed714	0:d616ece2d859	1098	}
mbed714	0:d616ece2d859	1099
mbed714	0:d616ece2d859	1100	/* Set retransmission timer running if it is not currently enabled */
mbed714	0:d616ece2d859	1101	if(pcb->rtime == -1) {
mbed714	0:d616ece2d859	1102	pcb->rtime = 0;
mbed714	0:d616ece2d859	1103	}
mbed714	0:d616ece2d859	1104
mbed714	0:d616ece2d859	1105	if (pcb->rttest == 0) {
mbed714	0:d616ece2d859	1106	pcb->rttest = tcp_ticks;
mbed714	0:d616ece2d859	1107	pcb->rtseq = ntohl(seg->tcphdr->seqno);
mbed714	0:d616ece2d859	1108
mbed714	0:d616ece2d859	1109	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
mbed714	0:d616ece2d859	1110	}
mbed714	0:d616ece2d859	1111	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
mbed714	0:d616ece2d859	1112	htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
mbed714	0:d616ece2d859	1113	seg->len));
mbed714	0:d616ece2d859	1114
mbed714	0:d616ece2d859	1115	len = (u16_t)((u8_t )seg->tcphdr - (u8_t )seg->p->payload);
mbed714	0:d616ece2d859	1116
mbed714	0:d616ece2d859	1117	seg->p->len -= len;
mbed714	0:d616ece2d859	1118	seg->p->tot_len -= len;
mbed714	0:d616ece2d859	1119
mbed714	0:d616ece2d859	1120	seg->p->payload = seg->tcphdr;
mbed714	0:d616ece2d859	1121
mbed714	0:d616ece2d859	1122	seg->tcphdr->chksum = 0;
mbed714	0:d616ece2d859	1123	#if CHECKSUM_GEN_TCP
mbed714	0:d616ece2d859	1124	#if TCP_CHECKSUM_ON_COPY
mbed714	0:d616ece2d859	1125	{
mbed714	0:d616ece2d859	1126	u32_t acc;
mbed714	0:d616ece2d859	1127	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
mbed714	0:d616ece2d859	1128	u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
mbed714	0:d616ece2d859	1129	&(pcb->remote_ip),
mbed714	0:d616ece2d859	1130	IP_PROTO_TCP, seg->p->tot_len);
mbed714	0:d616ece2d859	1131	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
mbed714	0:d616ece2d859	1132	if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
mbed714	0:d616ece2d859	1133	LWIP_ASSERT("data included but not checksummed",
mbed714	0:d616ece2d859	1134	seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
mbed714	0:d616ece2d859	1135	}
mbed714	0:d616ece2d859	1136
mbed714	0:d616ece2d859	1137	/* rebuild TCP header checksum (TCP header changes for retransmissions!) */
mbed714	0:d616ece2d859	1138	acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
mbed714	0:d616ece2d859	1139	&(pcb->remote_ip),
mbed714	0:d616ece2d859	1140	IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
mbed714	0:d616ece2d859	1141	/* add payload checksum */
mbed714	0:d616ece2d859	1142	if (seg->chksum_swapped) {
mbed714	0:d616ece2d859	1143	seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
mbed714	0:d616ece2d859	1144	seg->chksum_swapped = 0;
mbed714	0:d616ece2d859	1145	}
mbed714	0:d616ece2d859	1146	acc += (u16_t)~(seg->chksum);
mbed714	0:d616ece2d859	1147	seg->tcphdr->chksum = FOLD_U32T(acc);
mbed714	0:d616ece2d859	1148	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
mbed714	0:d616ece2d859	1149	if (chksum_slow != seg->tcphdr->chksum) {
mbed714	0:d616ece2d859	1150	LWIP_DEBUGF(TCP_DEBUG \| LWIP_DBG_LEVEL_WARNING,
mbed714	0:d616ece2d859	1151	("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
mbed714	0:d616ece2d859	1152	seg->tcphdr->chksum, chksum_slow));
mbed714	0:d616ece2d859	1153	seg->tcphdr->chksum = chksum_slow;
mbed714	0:d616ece2d859	1154	}
mbed714	0:d616ece2d859	1155	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
mbed714	0:d616ece2d859	1156	}
mbed714	0:d616ece2d859	1157	#else /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	1158	seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
mbed714	0:d616ece2d859	1159	&(pcb->remote_ip),
mbed714	0:d616ece2d859	1160	IP_PROTO_TCP, seg->p->tot_len);
mbed714	0:d616ece2d859	1161	#endif /* TCP_CHECKSUM_ON_COPY */
mbed714	0:d616ece2d859	1162	#endif /* CHECKSUM_GEN_TCP */
mbed714	0:d616ece2d859	1163	TCP_STATS_INC(tcp.xmit);
mbed714	0:d616ece2d859	1164
mbed714	0:d616ece2d859	1165	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: Before ip_out seqno = %"U32_F"\n",
mbed714	0:d616ece2d859	1166	htonl(seg->tcphdr->seqno))); //DG
mbed714	0:d616ece2d859	1167
mbed714	0:d616ece2d859	1168	#if LWIP_NETIF_HWADDRHINT
mbed714	0:d616ece2d859	1169	ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
mbed714	0:d616ece2d859	1170	IP_PROTO_TCP, &(pcb->addr_hint));
mbed714	0:d616ece2d859	1171	#else /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	1172	ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
mbed714	0:d616ece2d859	1173	IP_PROTO_TCP);
mbed714	0:d616ece2d859	1174	#endif /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	1175
mbed714	0:d616ece2d859	1176	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: After ip_out seqno = %"U32_F"\n",
mbed714	0:d616ece2d859	1177	htonl(seg->tcphdr->seqno))); //DG
mbed714	0:d616ece2d859	1178
mbed714	0:d616ece2d859	1179
mbed714	0:d616ece2d859	1180	}
mbed714	0:d616ece2d859	1181
mbed714	0:d616ece2d859	1182	/**
mbed714	0:d616ece2d859	1183	* Send a TCP RESET packet (empty segment with RST flag set) either to
mbed714	0:d616ece2d859	1184	* abort a connection or to show that there is no matching local connection
mbed714	0:d616ece2d859	1185	* for a received segment.
mbed714	0:d616ece2d859	1186	*
mbed714	0:d616ece2d859	1187	* Called by tcp_abort() (to abort a local connection), tcp_input() (if no
mbed714	0:d616ece2d859	1188	* matching local pcb was found), tcp_listen_input() (if incoming segment
mbed714	0:d616ece2d859	1189	* has ACK flag set) and tcp_process() (received segment in the wrong state)
mbed714	0:d616ece2d859	1190	*
mbed714	0:d616ece2d859	1191	* Since a RST segment is in most cases not sent for an active connection,
mbed714	0:d616ece2d859	1192	* tcp_rst() has a number of arguments that are taken from a tcp_pcb for
mbed714	0:d616ece2d859	1193	* most other segment output functions.
mbed714	0:d616ece2d859	1194	*
mbed714	0:d616ece2d859	1195	* @param seqno the sequence number to use for the outgoing segment
mbed714	0:d616ece2d859	1196	* @param ackno the acknowledge number to use for the outgoing segment
mbed714	0:d616ece2d859	1197	* @param local_ip the local IP address to send the segment from
mbed714	0:d616ece2d859	1198	* @param remote_ip the remote IP address to send the segment to
mbed714	0:d616ece2d859	1199	* @param local_port the local TCP port to send the segment from
mbed714	0:d616ece2d859	1200	* @param remote_port the remote TCP port to send the segment to
mbed714	0:d616ece2d859	1201	*/
mbed714	0:d616ece2d859	1202	void
mbed714	0:d616ece2d859	1203	tcp_rst(u32_t seqno, u32_t ackno,
mbed714	0:d616ece2d859	1204	ip_addr_t local_ip, ip_addr_t remote_ip,
mbed714	0:d616ece2d859	1205	u16_t local_port, u16_t remote_port)
mbed714	0:d616ece2d859	1206	{
mbed714	0:d616ece2d859	1207	struct pbuf *p;
mbed714	0:d616ece2d859	1208	struct tcp_hdr *tcphdr;
mbed714	0:d616ece2d859	1209	p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
mbed714	0:d616ece2d859	1210	if (p == NULL) {
mbed714	0:d616ece2d859	1211	LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
mbed714	0:d616ece2d859	1212	return;
mbed714	0:d616ece2d859	1213	}
mbed714	0:d616ece2d859	1214	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
mbed714	0:d616ece2d859	1215	(p->len >= sizeof(struct tcp_hdr)));
mbed714	0:d616ece2d859	1216
mbed714	0:d616ece2d859	1217	tcphdr = (struct tcp_hdr *)p->payload;
mbed714	0:d616ece2d859	1218	tcphdr->src = htons(local_port);
mbed714	0:d616ece2d859	1219	tcphdr->dest = htons(remote_port);
mbed714	0:d616ece2d859	1220	tcphdr->seqno = htonl(seqno);
mbed714	0:d616ece2d859	1221	tcphdr->ackno = htonl(ackno);
mbed714	0:d616ece2d859	1222	TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST \| TCP_ACK);
mbed714	0:d616ece2d859	1223	tcphdr->wnd = PP_HTONS(TCP_WND);
mbed714	0:d616ece2d859	1224	tcphdr->chksum = 0;
mbed714	0:d616ece2d859	1225	tcphdr->urgp = 0;
mbed714	0:d616ece2d859	1226
mbed714	0:d616ece2d859	1227	#if CHECKSUM_GEN_TCP
mbed714	0:d616ece2d859	1228	tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
mbed714	0:d616ece2d859	1229	IP_PROTO_TCP, p->tot_len);
mbed714	0:d616ece2d859	1230	#endif
mbed714	0:d616ece2d859	1231	TCP_STATS_INC(tcp.xmit);
mbed714	0:d616ece2d859	1232	snmp_inc_tcpoutrsts();
mbed714	0:d616ece2d859	1233	/* Send output with hardcoded TTL since we have no access to the pcb */
mbed714	0:d616ece2d859	1234	ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
mbed714	0:d616ece2d859	1235	pbuf_free(p);
mbed714	0:d616ece2d859	1236	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
mbed714	0:d616ece2d859	1237	}
mbed714	0:d616ece2d859	1238
mbed714	0:d616ece2d859	1239	/**
mbed714	0:d616ece2d859	1240	* Requeue all unacked segments for retransmission
mbed714	0:d616ece2d859	1241	*
mbed714	0:d616ece2d859	1242	* Called by tcp_slowtmr() for slow retransmission.
mbed714	0:d616ece2d859	1243	*
mbed714	0:d616ece2d859	1244	* @param pcb the tcp_pcb for which to re-enqueue all unacked segments
mbed714	0:d616ece2d859	1245	*/
mbed714	0:d616ece2d859	1246	void
mbed714	0:d616ece2d859	1247	tcp_rexmit_rto(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	1248	{
mbed714	0:d616ece2d859	1249	struct tcp_seg *seg;
mbed714	0:d616ece2d859	1250
mbed714	0:d616ece2d859	1251	if (pcb->unacked == NULL) {
mbed714	0:d616ece2d859	1252	return;
mbed714	0:d616ece2d859	1253	}
mbed714	0:d616ece2d859	1254
mbed714	0:d616ece2d859	1255	/* Move all unacked segments to the head of the unsent queue */
mbed714	0:d616ece2d859	1256	for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
mbed714	0:d616ece2d859	1257	/* concatenate unsent queue after unacked queue */
mbed714	0:d616ece2d859	1258	seg->next = pcb->unsent;
mbed714	0:d616ece2d859	1259	/* unsent queue is the concatenated queue (of unacked, unsent) */
mbed714	0:d616ece2d859	1260	pcb->unsent = pcb->unacked;
mbed714	0:d616ece2d859	1261	/* unacked queue is now empty */
mbed714	0:d616ece2d859	1262	pcb->unacked = NULL;
mbed714	0:d616ece2d859	1263
mbed714	0:d616ece2d859	1264	/* increment number of retransmissions */
mbed714	0:d616ece2d859	1265	++pcb->nrtx;
mbed714	0:d616ece2d859	1266
mbed714	0:d616ece2d859	1267	/* Don't take any RTT measurements after retransmitting. */
mbed714	0:d616ece2d859	1268	pcb->rttest = 0;
mbed714	0:d616ece2d859	1269
mbed714	0:d616ece2d859	1270	/* Do the actual retransmission */
mbed714	0:d616ece2d859	1271	tcp_output(pcb);
mbed714	0:d616ece2d859	1272	}
mbed714	0:d616ece2d859	1273
mbed714	0:d616ece2d859	1274	/**
mbed714	0:d616ece2d859	1275	* Requeue the first unacked segment for retransmission
mbed714	0:d616ece2d859	1276	*
mbed714	0:d616ece2d859	1277	* Called by tcp_receive() for fast retramsmit.
mbed714	0:d616ece2d859	1278	*
mbed714	0:d616ece2d859	1279	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
mbed714	0:d616ece2d859	1280	*/
mbed714	0:d616ece2d859	1281	void
mbed714	0:d616ece2d859	1282	tcp_rexmit(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	1283	{
mbed714	0:d616ece2d859	1284	struct tcp_seg *seg;
mbed714	0:d616ece2d859	1285	struct tcp_seg **cur_seg;
mbed714	0:d616ece2d859	1286
mbed714	0:d616ece2d859	1287	if (pcb->unacked == NULL) {
mbed714	0:d616ece2d859	1288	return;
mbed714	0:d616ece2d859	1289	}
mbed714	0:d616ece2d859	1290
mbed714	0:d616ece2d859	1291	/* Move the first unacked segment to the unsent queue */
mbed714	0:d616ece2d859	1292	/* Keep the unsent queue sorted. */
mbed714	0:d616ece2d859	1293	seg = pcb->unacked;
mbed714	0:d616ece2d859	1294	pcb->unacked = seg->next;
mbed714	0:d616ece2d859	1295
mbed714	0:d616ece2d859	1296	cur_seg = &(pcb->unsent);
mbed714	0:d616ece2d859	1297	while (*cur_seg &&
mbed714	0:d616ece2d859	1298	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
mbed714	0:d616ece2d859	1299	cur_seg = &((*cur_seg)->next );
mbed714	0:d616ece2d859	1300	}
mbed714	0:d616ece2d859	1301	seg->next = *cur_seg;
mbed714	0:d616ece2d859	1302	*cur_seg = seg;
mbed714	0:d616ece2d859	1303
mbed714	0:d616ece2d859	1304	++pcb->nrtx;
mbed714	0:d616ece2d859	1305
mbed714	0:d616ece2d859	1306	/* Don't take any rtt measurements after retransmitting. */
mbed714	0:d616ece2d859	1307	pcb->rttest = 0;
mbed714	0:d616ece2d859	1308
mbed714	0:d616ece2d859	1309	/* Do the actual retransmission. */
mbed714	0:d616ece2d859	1310	snmp_inc_tcpretranssegs();
mbed714	0:d616ece2d859	1311	/* No need to call tcp_output: we are always called from tcp_input()
mbed714	0:d616ece2d859	1312	and thus tcp_output directly returns. */
mbed714	0:d616ece2d859	1313	}
mbed714	0:d616ece2d859	1314
mbed714	0:d616ece2d859	1315
mbed714	0:d616ece2d859	1316	/**
mbed714	0:d616ece2d859	1317	* Handle retransmission after three dupacks received
mbed714	0:d616ece2d859	1318	*
mbed714	0:d616ece2d859	1319	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
mbed714	0:d616ece2d859	1320	*/
mbed714	0:d616ece2d859	1321	void
mbed714	0:d616ece2d859	1322	tcp_rexmit_fast(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	1323	{
mbed714	0:d616ece2d859	1324	if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
mbed714	0:d616ece2d859	1325	/* This is fast retransmit. Retransmit the first unacked segment. */
mbed714	0:d616ece2d859	1326	LWIP_DEBUGF(TCP_FR_DEBUG,
mbed714	0:d616ece2d859	1327	("tcp_receive: dupacks %"U16_F" (%"U32_F
mbed714	0:d616ece2d859	1328	"), fast retransmit %"U32_F"\n",
mbed714	0:d616ece2d859	1329	(u16_t)pcb->dupacks, pcb->lastack,
mbed714	0:d616ece2d859	1330	ntohl(pcb->unacked->tcphdr->seqno)));
mbed714	0:d616ece2d859	1331	tcp_rexmit(pcb);
mbed714	0:d616ece2d859	1332
mbed714	0:d616ece2d859	1333	/* Set ssthresh to half of the minimum of the current
mbed714	0:d616ece2d859	1334	* cwnd and the advertised window */
mbed714	0:d616ece2d859	1335	if (pcb->cwnd > pcb->snd_wnd) {
mbed714	0:d616ece2d859	1336	pcb->ssthresh = pcb->snd_wnd / 2;
mbed714	0:d616ece2d859	1337	} else {
mbed714	0:d616ece2d859	1338	pcb->ssthresh = pcb->cwnd / 2;
mbed714	0:d616ece2d859	1339	}
mbed714	0:d616ece2d859	1340
mbed714	0:d616ece2d859	1341	/* The minimum value for ssthresh should be 2 MSS */
mbed714	0:d616ece2d859	1342	if (pcb->ssthresh < 2*pcb->mss) {
mbed714	0:d616ece2d859	1343	LWIP_DEBUGF(TCP_FR_DEBUG,
mbed714	0:d616ece2d859	1344	("tcp_receive: The minimum value for ssthresh %"U16_F
mbed714	0:d616ece2d859	1345	" should be min 2 mss %"U16_F"...\n",
mbed714	0:d616ece2d859	1346	pcb->ssthresh, 2*pcb->mss));
mbed714	0:d616ece2d859	1347	pcb->ssthresh = 2*pcb->mss;
mbed714	0:d616ece2d859	1348	}
mbed714	0:d616ece2d859	1349
mbed714	0:d616ece2d859	1350	pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
mbed714	0:d616ece2d859	1351	pcb->flags \|= TF_INFR;
mbed714	0:d616ece2d859	1352	}
mbed714	0:d616ece2d859	1353	}
mbed714	0:d616ece2d859	1354
mbed714	0:d616ece2d859	1355
mbed714	0:d616ece2d859	1356	/**
mbed714	0:d616ece2d859	1357	* Send keepalive packets to keep a connection active although
mbed714	0:d616ece2d859	1358	* no data is sent over it.
mbed714	0:d616ece2d859	1359	*
mbed714	0:d616ece2d859	1360	* Called by tcp_slowtmr()
mbed714	0:d616ece2d859	1361	*
mbed714	0:d616ece2d859	1362	* @param pcb the tcp_pcb for which to send a keepalive packet
mbed714	0:d616ece2d859	1363	*/
mbed714	0:d616ece2d859	1364	void
mbed714	0:d616ece2d859	1365	tcp_keepalive(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	1366	{
mbed714	0:d616ece2d859	1367	struct pbuf *p;
mbed714	0:d616ece2d859	1368	struct tcp_hdr *tcphdr;
mbed714	0:d616ece2d859	1369
mbed714	0:d616ece2d859	1370	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
mbed714	0:d616ece2d859	1371	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
mbed714	0:d616ece2d859	1372	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
mbed714	0:d616ece2d859	1373
mbed714	0:d616ece2d859	1374	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
mbed714	0:d616ece2d859	1375	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
mbed714	0:d616ece2d859	1376
mbed714	0:d616ece2d859	1377	p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
mbed714	0:d616ece2d859	1378	if(p == NULL) {
mbed714	0:d616ece2d859	1379	LWIP_DEBUGF(TCP_DEBUG,
mbed714	0:d616ece2d859	1380	("tcp_keepalive: could not allocate memory for pbuf\n"));
mbed714	0:d616ece2d859	1381	return;
mbed714	0:d616ece2d859	1382	}
mbed714	0:d616ece2d859	1383	tcphdr = (struct tcp_hdr *)p->payload;
mbed714	0:d616ece2d859	1384
mbed714	0:d616ece2d859	1385	#if CHECKSUM_GEN_TCP
mbed714	0:d616ece2d859	1386	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
mbed714	0:d616ece2d859	1387	IP_PROTO_TCP, p->tot_len);
mbed714	0:d616ece2d859	1388	#endif
mbed714	0:d616ece2d859	1389	TCP_STATS_INC(tcp.xmit);
mbed714	0:d616ece2d859	1390
mbed714	0:d616ece2d859	1391	/* Send output to IP */
mbed714	0:d616ece2d859	1392	#if LWIP_NETIF_HWADDRHINT
mbed714	0:d616ece2d859	1393	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
mbed714	0:d616ece2d859	1394	&(pcb->addr_hint));
mbed714	0:d616ece2d859	1395	#else /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	1396	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
mbed714	0:d616ece2d859	1397	#endif /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	1398
mbed714	0:d616ece2d859	1399	pbuf_free(p);
mbed714	0:d616ece2d859	1400
mbed714	0:d616ece2d859	1401	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
mbed714	0:d616ece2d859	1402	pcb->snd_nxt - 1, pcb->rcv_nxt));
mbed714	0:d616ece2d859	1403	}
mbed714	0:d616ece2d859	1404
mbed714	0:d616ece2d859	1405
mbed714	0:d616ece2d859	1406	/**
mbed714	0:d616ece2d859	1407	* Send persist timer zero-window probes to keep a connection active
mbed714	0:d616ece2d859	1408	* when a window update is lost.
mbed714	0:d616ece2d859	1409	*
mbed714	0:d616ece2d859	1410	* Called by tcp_slowtmr()
mbed714	0:d616ece2d859	1411	*
mbed714	0:d616ece2d859	1412	* @param pcb the tcp_pcb for which to send a zero-window probe packet
mbed714	0:d616ece2d859	1413	*/
mbed714	0:d616ece2d859	1414	void
mbed714	0:d616ece2d859	1415	tcp_zero_window_probe(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	1416	{
mbed714	0:d616ece2d859	1417	struct pbuf *p;
mbed714	0:d616ece2d859	1418	struct tcp_hdr *tcphdr;
mbed714	0:d616ece2d859	1419	struct tcp_seg *seg;
mbed714	0:d616ece2d859	1420	u16_t len;
mbed714	0:d616ece2d859	1421	u8_t is_fin;
mbed714	0:d616ece2d859	1422
mbed714	0:d616ece2d859	1423	LWIP_DEBUGF(TCP_DEBUG,
mbed714	0:d616ece2d859	1424	("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
mbed714	0:d616ece2d859	1425	U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
mbed714	0:d616ece2d859	1426	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
mbed714	0:d616ece2d859	1427	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
mbed714	0:d616ece2d859	1428
mbed714	0:d616ece2d859	1429	LWIP_DEBUGF(TCP_DEBUG,
mbed714	0:d616ece2d859	1430	("tcp_zero_window_probe: tcp_ticks %"U32_F
mbed714	0:d616ece2d859	1431	" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
mbed714	0:d616ece2d859	1432	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
mbed714	0:d616ece2d859	1433
mbed714	0:d616ece2d859	1434	seg = pcb->unacked;
mbed714	0:d616ece2d859	1435
mbed714	0:d616ece2d859	1436	if(seg == NULL) {
mbed714	0:d616ece2d859	1437	seg = pcb->unsent;
mbed714	0:d616ece2d859	1438	}
mbed714	0:d616ece2d859	1439	if(seg == NULL) {
mbed714	0:d616ece2d859	1440	return;
mbed714	0:d616ece2d859	1441	}
mbed714	0:d616ece2d859	1442
mbed714	0:d616ece2d859	1443	is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
mbed714	0:d616ece2d859	1444	/* we want to send one seqno: either FIN or data (no options) */
mbed714	0:d616ece2d859	1445	len = is_fin ? 0 : 1;
mbed714	0:d616ece2d859	1446
mbed714	0:d616ece2d859	1447	p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
mbed714	0:d616ece2d859	1448	if(p == NULL) {
mbed714	0:d616ece2d859	1449	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
mbed714	0:d616ece2d859	1450	return;
mbed714	0:d616ece2d859	1451	}
mbed714	0:d616ece2d859	1452	tcphdr = (struct tcp_hdr *)p->payload;
mbed714	0:d616ece2d859	1453
mbed714	0:d616ece2d859	1454	if (is_fin) {
mbed714	0:d616ece2d859	1455	/* FIN segment, no data */
mbed714	0:d616ece2d859	1456	TCPH_FLAGS_SET(tcphdr, TCP_ACK \| TCP_FIN);
mbed714	0:d616ece2d859	1457	} else {
mbed714	0:d616ece2d859	1458	/* Data segment, copy in one byte from the head of the unacked queue */
mbed714	0:d616ece2d859	1459	((char )p->payload + TCP_HLEN) = (char )seg->dataptr;
mbed714	0:d616ece2d859	1460	}
mbed714	0:d616ece2d859	1461
mbed714	0:d616ece2d859	1462	#if CHECKSUM_GEN_TCP
mbed714	0:d616ece2d859	1463	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
mbed714	0:d616ece2d859	1464	IP_PROTO_TCP, p->tot_len);
mbed714	0:d616ece2d859	1465	#endif
mbed714	0:d616ece2d859	1466	TCP_STATS_INC(tcp.xmit);
mbed714	0:d616ece2d859	1467
mbed714	0:d616ece2d859	1468	/* Send output to IP */
mbed714	0:d616ece2d859	1469	#if LWIP_NETIF_HWADDRHINT
mbed714	0:d616ece2d859	1470	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
mbed714	0:d616ece2d859	1471	&(pcb->addr_hint));
mbed714	0:d616ece2d859	1472	#else /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	1473	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
mbed714	0:d616ece2d859	1474	#endif /* LWIP_NETIF_HWADDRHINT*/
mbed714	0:d616ece2d859	1475
mbed714	0:d616ece2d859	1476	pbuf_free(p);
mbed714	0:d616ece2d859	1477
mbed714	0:d616ece2d859	1478	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
mbed714	0:d616ece2d859	1479	" ackno %"U32_F".\n",
mbed714	0:d616ece2d859	1480	pcb->snd_nxt - 1, pcb->rcv_nxt));
mbed714	0:d616ece2d859	1481	}
mbed714	0:d616ece2d859	1482	#endif /* LWIP_TCP */

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Type:	Library
Created:	18 Sep 2010
Imports:	1
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

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lwip/core/tcp_out.c@0:d616ece2d859, 2010-09-18 (annotated)

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