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This library is stripped down version of NetServices library. HTTP server and client function is NOT supported.

lwip/core/tcp_out.c@0:dcf3c92487ca, 2011-07-20 (annotated)

Committer:: idinor
Date:: Wed Jul 20 11:45:39 2011 +0000
Revision:: 0:dcf3c92487ca

Who changed what in which revision?

User	Revision	Line number	New contents of line
idinor	0:dcf3c92487ca	1	/**
idinor	0:dcf3c92487ca	2	* @file
idinor	0:dcf3c92487ca	3	* Transmission Control Protocol, outgoing traffic
idinor	0:dcf3c92487ca	4	*
idinor	0:dcf3c92487ca	5	* The output functions of TCP.
idinor	0:dcf3c92487ca	6	*
idinor	0:dcf3c92487ca	7	*/
idinor	0:dcf3c92487ca	8
idinor	0:dcf3c92487ca	9	/*
idinor	0:dcf3c92487ca	10	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
idinor	0:dcf3c92487ca	11	* All rights reserved.
idinor	0:dcf3c92487ca	12	*
idinor	0:dcf3c92487ca	13	* Redistribution and use in source and binary forms, with or without modification,
idinor	0:dcf3c92487ca	14	* are permitted provided that the following conditions are met:
idinor	0:dcf3c92487ca	15	*
idinor	0:dcf3c92487ca	16	* 1. Redistributions of source code must retain the above copyright notice,
idinor	0:dcf3c92487ca	17	* this list of conditions and the following disclaimer.
idinor	0:dcf3c92487ca	18	* 2. Redistributions in binary form must reproduce the above copyright notice,
idinor	0:dcf3c92487ca	19	* this list of conditions and the following disclaimer in the documentation
idinor	0:dcf3c92487ca	20	* and/or other materials provided with the distribution.
idinor	0:dcf3c92487ca	21	* 3. The name of the author may not be used to endorse or promote products
idinor	0:dcf3c92487ca	22	* derived from this software without specific prior written permission.
idinor	0:dcf3c92487ca	23	*
idinor	0:dcf3c92487ca	24	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
idinor	0:dcf3c92487ca	25	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
idinor	0:dcf3c92487ca	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
idinor	0:dcf3c92487ca	27	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
idinor	0:dcf3c92487ca	28	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
idinor	0:dcf3c92487ca	29	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
idinor	0:dcf3c92487ca	30	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
idinor	0:dcf3c92487ca	31	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
idinor	0:dcf3c92487ca	32	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
idinor	0:dcf3c92487ca	33	* OF SUCH DAMAGE.
idinor	0:dcf3c92487ca	34	*
idinor	0:dcf3c92487ca	35	* This file is part of the lwIP TCP/IP stack.
idinor	0:dcf3c92487ca	36	*
idinor	0:dcf3c92487ca	37	* Author: Adam Dunkels <adam@sics.se>
idinor	0:dcf3c92487ca	38	*
idinor	0:dcf3c92487ca	39	*/
idinor	0:dcf3c92487ca	40
idinor	0:dcf3c92487ca	41	#include "lwip/opt.h"
idinor	0:dcf3c92487ca	42
idinor	0:dcf3c92487ca	43	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
idinor	0:dcf3c92487ca	44
idinor	0:dcf3c92487ca	45	#include "lwip/tcp_impl.h"
idinor	0:dcf3c92487ca	46	#include "lwip/def.h"
idinor	0:dcf3c92487ca	47	#include "lwip/mem.h"
idinor	0:dcf3c92487ca	48	#include "lwip/memp.h"
idinor	0:dcf3c92487ca	49	#include "lwip/sys.h"
idinor	0:dcf3c92487ca	50	#include "lwip/ip_addr.h"
idinor	0:dcf3c92487ca	51	#include "lwip/netif.h"
idinor	0:dcf3c92487ca	52	#include "lwip/inet_chksum.h"
idinor	0:dcf3c92487ca	53	#include "lwip/stats.h"
idinor	0:dcf3c92487ca	54	#include "lwip/snmp.h"
idinor	0:dcf3c92487ca	55
idinor	0:dcf3c92487ca	56	#include <string.h>
idinor	0:dcf3c92487ca	57
idinor	0:dcf3c92487ca	58	/* Define some copy-macros for checksum-on-copy so that the code looks
idinor	0:dcf3c92487ca	59	nicer by preventing too many ifdef's. */
idinor	0:dcf3c92487ca	60	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	61	#define TCP_DATA_COPY(dst, src, len, seg) do { \
idinor	0:dcf3c92487ca	62	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
idinor	0:dcf3c92487ca	63	len, &seg->chksum, &seg->chksum_swapped); \
idinor	0:dcf3c92487ca	64	seg->flags \|= TF_SEG_DATA_CHECKSUMMED; } while(0)
idinor	0:dcf3c92487ca	65	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
idinor	0:dcf3c92487ca	66	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
idinor	0:dcf3c92487ca	67	#else /* TCP_CHECKSUM_ON_COPY*/
idinor	0:dcf3c92487ca	68	#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
idinor	0:dcf3c92487ca	69	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
idinor	0:dcf3c92487ca	70	#endif /* TCP_CHECKSUM_ON_COPY*/
idinor	0:dcf3c92487ca	71
idinor	0:dcf3c92487ca	72	/** Define this to 1 for an extra check that the output checksum is valid
idinor	0:dcf3c92487ca	73	* (usefule when the checksum is generated by the application, not the stack) */
idinor	0:dcf3c92487ca	74	#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
idinor	0:dcf3c92487ca	75	#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
idinor	0:dcf3c92487ca	76	#endif
idinor	0:dcf3c92487ca	77
idinor	0:dcf3c92487ca	78	/* Forward declarations.*/
idinor	0:dcf3c92487ca	79	static void tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb);
idinor	0:dcf3c92487ca	80
idinor	0:dcf3c92487ca	81	/** Allocate a pbuf and create a tcphdr at p->payload, used for output
idinor	0:dcf3c92487ca	82	* functions other than the default tcp_output -> tcp_output_segment
idinor	0:dcf3c92487ca	83	* (e.g. tcp_send_empty_ack, etc.)
idinor	0:dcf3c92487ca	84	*
idinor	0:dcf3c92487ca	85	* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
idinor	0:dcf3c92487ca	86	* @param optlen length of header-options
idinor	0:dcf3c92487ca	87	* @param datalen length of tcp data to reserve in pbuf
idinor	0:dcf3c92487ca	88	* @param seqno_be seqno in network byte order (big-endian)
idinor	0:dcf3c92487ca	89	* @return pbuf with p->payload being the tcp_hdr
idinor	0:dcf3c92487ca	90	*/
idinor	0:dcf3c92487ca	91	static struct pbuf *
idinor	0:dcf3c92487ca	92	tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
idinor	0:dcf3c92487ca	93	u32_t seqno_be /* already in network byte order */)
idinor	0:dcf3c92487ca	94	{
idinor	0:dcf3c92487ca	95	struct tcp_hdr *tcphdr;
idinor	0:dcf3c92487ca	96	struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
idinor	0:dcf3c92487ca	97	if (p != NULL) {
idinor	0:dcf3c92487ca	98	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
idinor	0:dcf3c92487ca	99	(p->len >= TCP_HLEN + optlen));
idinor	0:dcf3c92487ca	100	tcphdr = (struct tcp_hdr *)p->payload;
idinor	0:dcf3c92487ca	101	tcphdr->src = htons(pcb->local_port);
idinor	0:dcf3c92487ca	102	tcphdr->dest = htons(pcb->remote_port);
idinor	0:dcf3c92487ca	103	tcphdr->seqno = seqno_be;
idinor	0:dcf3c92487ca	104	tcphdr->ackno = htonl(pcb->rcv_nxt);
idinor	0:dcf3c92487ca	105	TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
idinor	0:dcf3c92487ca	106	tcphdr->wnd = htons(pcb->rcv_ann_wnd);
idinor	0:dcf3c92487ca	107	tcphdr->chksum = 0;
idinor	0:dcf3c92487ca	108	tcphdr->urgp = 0;
idinor	0:dcf3c92487ca	109
idinor	0:dcf3c92487ca	110	/* If we're sending a packet, update the announced right window edge */
idinor	0:dcf3c92487ca	111	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
idinor	0:dcf3c92487ca	112	}
idinor	0:dcf3c92487ca	113	return p;
idinor	0:dcf3c92487ca	114	}
idinor	0:dcf3c92487ca	115
idinor	0:dcf3c92487ca	116	/**
idinor	0:dcf3c92487ca	117	* Called by tcp_close() to send a segment including FIN flag but not data.
idinor	0:dcf3c92487ca	118	*
idinor	0:dcf3c92487ca	119	* @param pcb the tcp_pcb over which to send a segment
idinor	0:dcf3c92487ca	120	* @return ERR_OK if sent, another err_t otherwise
idinor	0:dcf3c92487ca	121	*/
idinor	0:dcf3c92487ca	122	err_t
idinor	0:dcf3c92487ca	123	tcp_send_fin(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	124	{
idinor	0:dcf3c92487ca	125	/* first, try to add the fin to the last unsent segment */
idinor	0:dcf3c92487ca	126	if (pcb->unsent != NULL) {
idinor	0:dcf3c92487ca	127	struct tcp_seg *last_unsent;
idinor	0:dcf3c92487ca	128	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
idinor	0:dcf3c92487ca	129	last_unsent = last_unsent->next);
idinor	0:dcf3c92487ca	130
idinor	0:dcf3c92487ca	131	if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN \| TCP_FIN \| TCP_RST)) == 0) {
idinor	0:dcf3c92487ca	132	/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
idinor	0:dcf3c92487ca	133	TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
idinor	0:dcf3c92487ca	134	return ERR_OK;
idinor	0:dcf3c92487ca	135	}
idinor	0:dcf3c92487ca	136	}
idinor	0:dcf3c92487ca	137	/* no data, no length, flags, copy=1, no optdata */
idinor	0:dcf3c92487ca	138	return tcp_enqueue_flags(pcb, TCP_FIN);
idinor	0:dcf3c92487ca	139	}
idinor	0:dcf3c92487ca	140
idinor	0:dcf3c92487ca	141	/**
idinor	0:dcf3c92487ca	142	* Create a TCP segment with prefilled header.
idinor	0:dcf3c92487ca	143	*
idinor	0:dcf3c92487ca	144	* Called by tcp_write and tcp_enqueue_flags.
idinor	0:dcf3c92487ca	145	*
idinor	0:dcf3c92487ca	146	* @param pcb Protocol control block for the TCP connection.
idinor	0:dcf3c92487ca	147	* @param p pbuf that is used to hold the TCP header.
idinor	0:dcf3c92487ca	148	* @param flags TCP flags for header.
idinor	0:dcf3c92487ca	149	* @param seqno TCP sequence number of this packet
idinor	0:dcf3c92487ca	150	* @param optflags options to include in TCP header
idinor	0:dcf3c92487ca	151	* @return a new tcp_seg pointing to p, or NULL.
idinor	0:dcf3c92487ca	152	* The TCP header is filled in except ackno and wnd.
idinor	0:dcf3c92487ca	153	* p is freed on failure.
idinor	0:dcf3c92487ca	154	*/
idinor	0:dcf3c92487ca	155	static struct tcp_seg *
idinor	0:dcf3c92487ca	156	tcp_create_segment(struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
idinor	0:dcf3c92487ca	157	{
idinor	0:dcf3c92487ca	158	struct tcp_seg *seg;
idinor	0:dcf3c92487ca	159	u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
idinor	0:dcf3c92487ca	160
idinor	0:dcf3c92487ca	161	if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
idinor	0:dcf3c92487ca	162	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no memory.\n"));
idinor	0:dcf3c92487ca	163	pbuf_free(p);
idinor	0:dcf3c92487ca	164	return NULL;
idinor	0:dcf3c92487ca	165	}
idinor	0:dcf3c92487ca	166	seg->flags = optflags;
idinor	0:dcf3c92487ca	167	seg->next = NULL;
idinor	0:dcf3c92487ca	168	seg->p = p;
idinor	0:dcf3c92487ca	169	seg->dataptr = p->payload;
idinor	0:dcf3c92487ca	170	seg->len = p->tot_len - optlen;
idinor	0:dcf3c92487ca	171	#if TCP_OVERSIZE_DBGCHECK
idinor	0:dcf3c92487ca	172	seg->oversize_left = 0;
idinor	0:dcf3c92487ca	173	#endif /* TCP_OVERSIZE_DBGCHECK */
idinor	0:dcf3c92487ca	174	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	175	seg->chksum = 0;
idinor	0:dcf3c92487ca	176	seg->chksum_swapped = 0;
idinor	0:dcf3c92487ca	177	/* check optflags */
idinor	0:dcf3c92487ca	178	LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
idinor	0:dcf3c92487ca	179	(optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
idinor	0:dcf3c92487ca	180	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	181
idinor	0:dcf3c92487ca	182	/* build TCP header */
idinor	0:dcf3c92487ca	183	if (pbuf_header(p, TCP_HLEN)) {
idinor	0:dcf3c92487ca	184	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
idinor	0:dcf3c92487ca	185	TCP_STATS_INC(tcp.err);
idinor	0:dcf3c92487ca	186	tcp_seg_free(seg);
idinor	0:dcf3c92487ca	187	return NULL;
idinor	0:dcf3c92487ca	188	}
idinor	0:dcf3c92487ca	189	seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
idinor	0:dcf3c92487ca	190	seg->tcphdr->src = htons(pcb->local_port);
idinor	0:dcf3c92487ca	191	seg->tcphdr->dest = htons(pcb->remote_port);
idinor	0:dcf3c92487ca	192	seg->tcphdr->seqno = htonl(seqno);
idinor	0:dcf3c92487ca	193	/* ackno is set in tcp_output */
idinor	0:dcf3c92487ca	194	TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
idinor	0:dcf3c92487ca	195	/* wnd and chksum are set in tcp_output */
idinor	0:dcf3c92487ca	196	seg->tcphdr->urgp = 0;
idinor	0:dcf3c92487ca	197	return seg;
idinor	0:dcf3c92487ca	198	}
idinor	0:dcf3c92487ca	199
idinor	0:dcf3c92487ca	200	/**
idinor	0:dcf3c92487ca	201	* Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
idinor	0:dcf3c92487ca	202	*
idinor	0:dcf3c92487ca	203	* This function is like pbuf_alloc(layer, length, PBUF_RAM) except
idinor	0:dcf3c92487ca	204	* there may be extra bytes available at the end.
idinor	0:dcf3c92487ca	205	*
idinor	0:dcf3c92487ca	206	* @param layer flag to define header size.
idinor	0:dcf3c92487ca	207	* @param length size of the pbuf's payload.
idinor	0:dcf3c92487ca	208	* @param max_length maximum usable size of payload+oversize.
idinor	0:dcf3c92487ca	209	* @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
idinor	0:dcf3c92487ca	210	* @param pcb The TCP connection that willo enqueue the pbuf.
idinor	0:dcf3c92487ca	211	* @param apiflags API flags given to tcp_write.
idinor	0:dcf3c92487ca	212	* @param first_seg true when this pbuf will be used in the first enqueued segment.
idinor	0:dcf3c92487ca	213	* @param
idinor	0:dcf3c92487ca	214	*/
idinor	0:dcf3c92487ca	215	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	216	static struct pbuf *
idinor	0:dcf3c92487ca	217	tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
idinor	0:dcf3c92487ca	218	u16_t oversize, struct tcp_pcb pcb, u8_t apiflags,
idinor	0:dcf3c92487ca	219	u8_t first_seg)
idinor	0:dcf3c92487ca	220	{
idinor	0:dcf3c92487ca	221	struct pbuf *p;
idinor	0:dcf3c92487ca	222	u16_t alloc = length;
idinor	0:dcf3c92487ca	223
idinor	0:dcf3c92487ca	224	#if LWIP_NETIF_TX_SINGLE_PBUF
idinor	0:dcf3c92487ca	225	LWIP_UNUSED_ARG(max_length);
idinor	0:dcf3c92487ca	226	LWIP_UNUSED_ARG(pcb);
idinor	0:dcf3c92487ca	227	LWIP_UNUSED_ARG(apiflags);
idinor	0:dcf3c92487ca	228	LWIP_UNUSED_ARG(first_seg);
idinor	0:dcf3c92487ca	229	/* always create MSS-sized pbufs */
idinor	0:dcf3c92487ca	230	alloc = TCP_MSS;
idinor	0:dcf3c92487ca	231	#else /* LWIP_NETIF_TX_SINGLE_PBUF */
idinor	0:dcf3c92487ca	232	if (length < max_length) {
idinor	0:dcf3c92487ca	233	/* Should we allocate an oversized pbuf, or just the minimum
idinor	0:dcf3c92487ca	234	* length required? If tcp_write is going to be called again
idinor	0:dcf3c92487ca	235	* before this segment is transmitted, we want the oversized
idinor	0:dcf3c92487ca	236	* buffer. If the segment will be transmitted immediately, we can
idinor	0:dcf3c92487ca	237	* save memory by allocating only length. We use a simple
idinor	0:dcf3c92487ca	238	* heuristic based on the following information:
idinor	0:dcf3c92487ca	239	*
idinor	0:dcf3c92487ca	240	* Did the user set TCP_WRITE_FLAG_MORE?
idinor	0:dcf3c92487ca	241	*
idinor	0:dcf3c92487ca	242	* Will the Nagle algorithm defer transmission of this segment?
idinor	0:dcf3c92487ca	243	*/
idinor	0:dcf3c92487ca	244	if ((apiflags & TCP_WRITE_FLAG_MORE) \|\|
idinor	0:dcf3c92487ca	245	(!(pcb->flags & TF_NODELAY) &&
idinor	0:dcf3c92487ca	246	(!first_seg \|\|
idinor	0:dcf3c92487ca	247	pcb->unsent != NULL \|\|
idinor	0:dcf3c92487ca	248	pcb->unacked != NULL))) {
idinor	0:dcf3c92487ca	249	alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
idinor	0:dcf3c92487ca	250	}
idinor	0:dcf3c92487ca	251	}
idinor	0:dcf3c92487ca	252	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
idinor	0:dcf3c92487ca	253	p = pbuf_alloc(layer, alloc, PBUF_RAM);
idinor	0:dcf3c92487ca	254	if (p == NULL) {
idinor	0:dcf3c92487ca	255	return NULL;
idinor	0:dcf3c92487ca	256	}
idinor	0:dcf3c92487ca	257	LWIP_ASSERT("need unchained pbuf", p->next == NULL);
idinor	0:dcf3c92487ca	258	*oversize = p->len - length;
idinor	0:dcf3c92487ca	259	/* trim p->len to the currently used size */
idinor	0:dcf3c92487ca	260	p->len = p->tot_len = length;
idinor	0:dcf3c92487ca	261	return p;
idinor	0:dcf3c92487ca	262	}
idinor	0:dcf3c92487ca	263	#else /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	264	#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
idinor	0:dcf3c92487ca	265	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	266
idinor	0:dcf3c92487ca	267	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	268	/** Add a checksum of newly added data to the segment */
idinor	0:dcf3c92487ca	269	static void
idinor	0:dcf3c92487ca	270	tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
idinor	0:dcf3c92487ca	271	u8_t *seg_chksum_swapped)
idinor	0:dcf3c92487ca	272	{
idinor	0:dcf3c92487ca	273	u32_t helper;
idinor	0:dcf3c92487ca	274	/* add chksum to old chksum and fold to u16_t */
idinor	0:dcf3c92487ca	275	helper = chksum + *seg_chksum;
idinor	0:dcf3c92487ca	276	chksum = FOLD_U32T(helper);
idinor	0:dcf3c92487ca	277	if ((len & 1) != 0) {
idinor	0:dcf3c92487ca	278	seg_chksum_swapped = 1 - seg_chksum_swapped;
idinor	0:dcf3c92487ca	279	chksum = SWAP_BYTES_IN_WORD(chksum);
idinor	0:dcf3c92487ca	280	}
idinor	0:dcf3c92487ca	281	*seg_chksum = chksum;
idinor	0:dcf3c92487ca	282	}
idinor	0:dcf3c92487ca	283	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	284
idinor	0:dcf3c92487ca	285	/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
idinor	0:dcf3c92487ca	286	*
idinor	0:dcf3c92487ca	287	* @param pcb the tcp pcb to check for
idinor	0:dcf3c92487ca	288	* @param len length of data to send (checked agains snd_buf)
idinor	0:dcf3c92487ca	289	* @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
idinor	0:dcf3c92487ca	290	*/
idinor	0:dcf3c92487ca	291	static err_t
idinor	0:dcf3c92487ca	292	tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
idinor	0:dcf3c92487ca	293	{
idinor	0:dcf3c92487ca	294	/* connection is in invalid state for data transmission? */
idinor	0:dcf3c92487ca	295	if ((pcb->state != ESTABLISHED) &&
idinor	0:dcf3c92487ca	296	(pcb->state != CLOSE_WAIT) &&
idinor	0:dcf3c92487ca	297	(pcb->state != SYN_SENT) &&
idinor	0:dcf3c92487ca	298	(pcb->state != SYN_RCVD)) {
idinor	0:dcf3c92487ca	299	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_STATE \| LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
idinor	0:dcf3c92487ca	300	return ERR_CONN;
idinor	0:dcf3c92487ca	301	} else if (len == 0) {
idinor	0:dcf3c92487ca	302	return ERR_OK;
idinor	0:dcf3c92487ca	303	}
idinor	0:dcf3c92487ca	304
idinor	0:dcf3c92487ca	305	/* fail on too much data */
idinor	0:dcf3c92487ca	306	if (len > pcb->snd_buf) {
idinor	0:dcf3c92487ca	307	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
idinor	0:dcf3c92487ca	308	len, pcb->snd_buf));
idinor	0:dcf3c92487ca	309	pcb->flags \|= TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	310	return ERR_MEM;
idinor	0:dcf3c92487ca	311	}
idinor	0:dcf3c92487ca	312
idinor	0:dcf3c92487ca	313	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	314
idinor	0:dcf3c92487ca	315	/* If total number of pbufs on the unsent/unacked queues exceeds the
idinor	0:dcf3c92487ca	316	* configured maximum, return an error */
idinor	0:dcf3c92487ca	317	/* check for configured max queuelen and possible overflow */
idinor	0:dcf3c92487ca	318	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
idinor	0:dcf3c92487ca	319	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
idinor	0:dcf3c92487ca	320	pcb->snd_queuelen, TCP_SND_QUEUELEN));
idinor	0:dcf3c92487ca	321	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	322	pcb->flags \|= TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	323	return ERR_MEM;
idinor	0:dcf3c92487ca	324	}
idinor	0:dcf3c92487ca	325	if (pcb->snd_queuelen != 0) {
idinor	0:dcf3c92487ca	326	LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
idinor	0:dcf3c92487ca	327	pcb->unacked != NULL \|\| pcb->unsent != NULL);
idinor	0:dcf3c92487ca	328	} else {
idinor	0:dcf3c92487ca	329	LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
idinor	0:dcf3c92487ca	330	pcb->unacked == NULL && pcb->unsent == NULL);
idinor	0:dcf3c92487ca	331	}
idinor	0:dcf3c92487ca	332	return ERR_OK;
idinor	0:dcf3c92487ca	333	}
idinor	0:dcf3c92487ca	334
idinor	0:dcf3c92487ca	335	/**
idinor	0:dcf3c92487ca	336	* Write data for sending (but does not send it immediately).
idinor	0:dcf3c92487ca	337	*
idinor	0:dcf3c92487ca	338	* It waits in the expectation of more data being sent soon (as
idinor	0:dcf3c92487ca	339	* it can send them more efficiently by combining them together).
idinor	0:dcf3c92487ca	340	* To prompt the system to send data now, call tcp_output() after
idinor	0:dcf3c92487ca	341	* calling tcp_write().
idinor	0:dcf3c92487ca	342	*
idinor	0:dcf3c92487ca	343	* @param pcb Protocol control block for the TCP connection to enqueue data for.
idinor	0:dcf3c92487ca	344	* @param arg Pointer to the data to be enqueued for sending.
idinor	0:dcf3c92487ca	345	* @param len Data length in bytes
idinor	0:dcf3c92487ca	346	* @param apiflags combination of following flags :
idinor	0:dcf3c92487ca	347	* - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
idinor	0:dcf3c92487ca	348	* - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
idinor	0:dcf3c92487ca	349	* @return ERR_OK if enqueued, another err_t on error
idinor	0:dcf3c92487ca	350	*/
idinor	0:dcf3c92487ca	351	err_t
idinor	0:dcf3c92487ca	352	tcp_write(struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
idinor	0:dcf3c92487ca	353	{
idinor	0:dcf3c92487ca	354	struct pbuf *concat_p = NULL;
idinor	0:dcf3c92487ca	355	struct tcp_seg last_unsent = NULL, seg = NULL, prev_seg = NULL, queue = NULL;
idinor	0:dcf3c92487ca	356	u16_t pos = 0; /* position in 'arg' data */
idinor	0:dcf3c92487ca	357	u16_t queuelen;
idinor	0:dcf3c92487ca	358	u8_t optlen = 0;
idinor	0:dcf3c92487ca	359	u8_t optflags = 0;
idinor	0:dcf3c92487ca	360	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	361	u16_t oversize = 0;
idinor	0:dcf3c92487ca	362	u16_t oversize_used = 0;
idinor	0:dcf3c92487ca	363	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	364	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	365	u16_t concat_chksum = 0;
idinor	0:dcf3c92487ca	366	u8_t concat_chksum_swapped = 0;
idinor	0:dcf3c92487ca	367	u16_t concat_chksummed = 0;
idinor	0:dcf3c92487ca	368	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	369	err_t err;
idinor	0:dcf3c92487ca	370
idinor	0:dcf3c92487ca	371	#if LWIP_NETIF_TX_SINGLE_PBUF
idinor	0:dcf3c92487ca	372	/* Always copy to try to create single pbufs for TX */
idinor	0:dcf3c92487ca	373	apiflags \|= TCP_WRITE_FLAG_COPY;
idinor	0:dcf3c92487ca	374	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
idinor	0:dcf3c92487ca	375
idinor	0:dcf3c92487ca	376	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
idinor	0:dcf3c92487ca	377	(void *)pcb, arg, len, (u16_t)apiflags));
idinor	0:dcf3c92487ca	378	LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
idinor	0:dcf3c92487ca	379	arg != NULL, return ERR_ARG;);
idinor	0:dcf3c92487ca	380
idinor	0:dcf3c92487ca	381	err = tcp_write_checks(pcb, len);
idinor	0:dcf3c92487ca	382	if (err != ERR_OK) {
idinor	0:dcf3c92487ca	383	return err;
idinor	0:dcf3c92487ca	384	}
idinor	0:dcf3c92487ca	385	queuelen = pcb->snd_queuelen;
idinor	0:dcf3c92487ca	386
idinor	0:dcf3c92487ca	387	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	388	if ((pcb->flags & TF_TIMESTAMP)) {
idinor	0:dcf3c92487ca	389	optflags = TF_SEG_OPTS_TS;
idinor	0:dcf3c92487ca	390	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
idinor	0:dcf3c92487ca	391	}
idinor	0:dcf3c92487ca	392	#endif /* LWIP_TCP_TIMESTAMPS */
idinor	0:dcf3c92487ca	393
idinor	0:dcf3c92487ca	394
idinor	0:dcf3c92487ca	395	/*
idinor	0:dcf3c92487ca	396	* TCP segmentation is done in three phases with increasing complexity:
idinor	0:dcf3c92487ca	397	*
idinor	0:dcf3c92487ca	398	* 1. Copy data directly into an oversized pbuf.
idinor	0:dcf3c92487ca	399	* 2. Chain a new pbuf to the end of pcb->unsent.
idinor	0:dcf3c92487ca	400	* 3. Create new segments.
idinor	0:dcf3c92487ca	401	*
idinor	0:dcf3c92487ca	402	* We may run out of memory at any point. In that case we must
idinor	0:dcf3c92487ca	403	* return ERR_MEM and not change anything in pcb. Therefore, all
idinor	0:dcf3c92487ca	404	* changes are recorded in local variables and committed at the end
idinor	0:dcf3c92487ca	405	* of the function. Some pcb fields are maintained in local copies:
idinor	0:dcf3c92487ca	406	*
idinor	0:dcf3c92487ca	407	* queuelen = pcb->snd_queuelen
idinor	0:dcf3c92487ca	408	* oversize = pcb->unsent_oversize
idinor	0:dcf3c92487ca	409	*
idinor	0:dcf3c92487ca	410	* These variables are set consistently by the phases:
idinor	0:dcf3c92487ca	411	*
idinor	0:dcf3c92487ca	412	* seg points to the last segment tampered with.
idinor	0:dcf3c92487ca	413	*
idinor	0:dcf3c92487ca	414	* pos records progress as data is segmented.
idinor	0:dcf3c92487ca	415	*/
idinor	0:dcf3c92487ca	416
idinor	0:dcf3c92487ca	417	/* Find the tail of the unsent queue. */
idinor	0:dcf3c92487ca	418	if (pcb->unsent != NULL) {
idinor	0:dcf3c92487ca	419	u16_t space;
idinor	0:dcf3c92487ca	420	u16_t unsent_optlen;
idinor	0:dcf3c92487ca	421
idinor	0:dcf3c92487ca	422	/* @todo: this could be sped up by keeping last_unsent in the pcb */
idinor	0:dcf3c92487ca	423	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
idinor	0:dcf3c92487ca	424	last_unsent = last_unsent->next);
idinor	0:dcf3c92487ca	425
idinor	0:dcf3c92487ca	426	/* Usable space at the end of the last unsent segment */
idinor	0:dcf3c92487ca	427	unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
idinor	0:dcf3c92487ca	428	space = pcb->mss - (last_unsent->len + unsent_optlen);
idinor	0:dcf3c92487ca	429
idinor	0:dcf3c92487ca	430	/*
idinor	0:dcf3c92487ca	431	* Phase 1: Copy data directly into an oversized pbuf.
idinor	0:dcf3c92487ca	432	*
idinor	0:dcf3c92487ca	433	* The number of bytes copied is recorded in the oversize_used
idinor	0:dcf3c92487ca	434	* variable. The actual copying is done at the bottom of the
idinor	0:dcf3c92487ca	435	* function.
idinor	0:dcf3c92487ca	436	*/
idinor	0:dcf3c92487ca	437	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	438	#if TCP_OVERSIZE_DBGCHECK
idinor	0:dcf3c92487ca	439	/* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
idinor	0:dcf3c92487ca	440	LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
idinor	0:dcf3c92487ca	441	pcb->unsent_oversize == last_unsent->oversize_left);
idinor	0:dcf3c92487ca	442	#endif /* TCP_OVERSIZE_DBGCHECK */
idinor	0:dcf3c92487ca	443	oversize = pcb->unsent_oversize;
idinor	0:dcf3c92487ca	444	if (oversize > 0) {
idinor	0:dcf3c92487ca	445	LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
idinor	0:dcf3c92487ca	446	seg = last_unsent;
idinor	0:dcf3c92487ca	447	oversize_used = oversize < len ? oversize : len;
idinor	0:dcf3c92487ca	448	pos += oversize_used;
idinor	0:dcf3c92487ca	449	oversize -= oversize_used;
idinor	0:dcf3c92487ca	450	space -= oversize_used;
idinor	0:dcf3c92487ca	451	}
idinor	0:dcf3c92487ca	452	/* now we are either finished or oversize is zero */
idinor	0:dcf3c92487ca	453	LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) \|\| (pos == len));
idinor	0:dcf3c92487ca	454	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	455
idinor	0:dcf3c92487ca	456	/*
idinor	0:dcf3c92487ca	457	* Phase 2: Chain a new pbuf to the end of pcb->unsent.
idinor	0:dcf3c92487ca	458	*
idinor	0:dcf3c92487ca	459	* We don't extend segments containing SYN/FIN flags or options
idinor	0:dcf3c92487ca	460	* (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
idinor	0:dcf3c92487ca	461	* the end.
idinor	0:dcf3c92487ca	462	*/
idinor	0:dcf3c92487ca	463	if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
idinor	0:dcf3c92487ca	464	u16_t seglen = space < len - pos ? space : len - pos;
idinor	0:dcf3c92487ca	465	seg = last_unsent;
idinor	0:dcf3c92487ca	466
idinor	0:dcf3c92487ca	467	/* Create a pbuf with a copy or reference to seglen bytes. We
idinor	0:dcf3c92487ca	468	* can use PBUF_RAW here since the data appears in the middle of
idinor	0:dcf3c92487ca	469	* a segment. A header will never be prepended. */
idinor	0:dcf3c92487ca	470	if (apiflags & TCP_WRITE_FLAG_COPY) {
idinor	0:dcf3c92487ca	471	/* Data is copied */
idinor	0:dcf3c92487ca	472	if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
idinor	0:dcf3c92487ca	473	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
idinor	0:dcf3c92487ca	474	("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
idinor	0:dcf3c92487ca	475	seglen));
idinor	0:dcf3c92487ca	476	goto memerr;
idinor	0:dcf3c92487ca	477	}
idinor	0:dcf3c92487ca	478	#if TCP_OVERSIZE_DBGCHECK
idinor	0:dcf3c92487ca	479	last_unsent->oversize_left = oversize;
idinor	0:dcf3c92487ca	480	#endif /* TCP_OVERSIZE_DBGCHECK */
idinor	0:dcf3c92487ca	481	TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
idinor	0:dcf3c92487ca	482	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	483	concat_chksummed += seglen;
idinor	0:dcf3c92487ca	484	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	485	} else {
idinor	0:dcf3c92487ca	486	/* Data is not copied */
idinor	0:dcf3c92487ca	487	if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
idinor	0:dcf3c92487ca	488	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
idinor	0:dcf3c92487ca	489	("tcp_write: could not allocate memory for zero-copy pbuf\n"));
idinor	0:dcf3c92487ca	490	goto memerr;
idinor	0:dcf3c92487ca	491	}
idinor	0:dcf3c92487ca	492	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	493	/* calculate the checksum of nocopy-data */
idinor	0:dcf3c92487ca	494	tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
idinor	0:dcf3c92487ca	495	&concat_chksum, &concat_chksum_swapped);
idinor	0:dcf3c92487ca	496	concat_chksummed += seglen;
idinor	0:dcf3c92487ca	497	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	498	/* reference the non-volatile payload data */
idinor	0:dcf3c92487ca	499	concat_p->payload = (u8_t*)arg + pos;
idinor	0:dcf3c92487ca	500	}
idinor	0:dcf3c92487ca	501
idinor	0:dcf3c92487ca	502	pos += seglen;
idinor	0:dcf3c92487ca	503	queuelen += pbuf_clen(concat_p);
idinor	0:dcf3c92487ca	504	}
idinor	0:dcf3c92487ca	505	} else {
idinor	0:dcf3c92487ca	506	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	507	LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
idinor	0:dcf3c92487ca	508	pcb->unsent_oversize == 0);
idinor	0:dcf3c92487ca	509	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	510	}
idinor	0:dcf3c92487ca	511
idinor	0:dcf3c92487ca	512	/*
idinor	0:dcf3c92487ca	513	* Phase 3: Create new segments.
idinor	0:dcf3c92487ca	514	*
idinor	0:dcf3c92487ca	515	* The new segments are chained together in the local 'queue'
idinor	0:dcf3c92487ca	516	* variable, ready to be appended to pcb->unsent.
idinor	0:dcf3c92487ca	517	*/
idinor	0:dcf3c92487ca	518	while (pos < len) {
idinor	0:dcf3c92487ca	519	struct pbuf *p;
idinor	0:dcf3c92487ca	520	u16_t left = len - pos;
idinor	0:dcf3c92487ca	521	u16_t max_len = pcb->mss - optlen;
idinor	0:dcf3c92487ca	522	u16_t seglen = left > max_len ? max_len : left;
idinor	0:dcf3c92487ca	523	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	524	u16_t chksum = 0;
idinor	0:dcf3c92487ca	525	u8_t chksum_swapped = 0;
idinor	0:dcf3c92487ca	526	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	527
idinor	0:dcf3c92487ca	528	if (apiflags & TCP_WRITE_FLAG_COPY) {
idinor	0:dcf3c92487ca	529	/* If copy is set, memory should be allocated and data copied
idinor	0:dcf3c92487ca	530	* into pbuf */
idinor	0:dcf3c92487ca	531	if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, pcb->mss, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
idinor	0:dcf3c92487ca	532	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
idinor	0:dcf3c92487ca	533	goto memerr;
idinor	0:dcf3c92487ca	534	}
idinor	0:dcf3c92487ca	535	LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
idinor	0:dcf3c92487ca	536	(p->len >= seglen));
idinor	0:dcf3c92487ca	537	TCP_DATA_COPY2((char )p->payload + optlen, (u8_t)arg + pos, seglen, &chksum, &chksum_swapped);
idinor	0:dcf3c92487ca	538	} else {
idinor	0:dcf3c92487ca	539	/* Copy is not set: First allocate a pbuf for holding the data.
idinor	0:dcf3c92487ca	540	* Since the referenced data is available at least until it is
idinor	0:dcf3c92487ca	541	* sent out on the link (as it has to be ACKed by the remote
idinor	0:dcf3c92487ca	542	* party) we can safely use PBUF_ROM instead of PBUF_REF here.
idinor	0:dcf3c92487ca	543	*/
idinor	0:dcf3c92487ca	544	struct pbuf *p2;
idinor	0:dcf3c92487ca	545	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	546	LWIP_ASSERT("oversize == 0", oversize == 0);
idinor	0:dcf3c92487ca	547	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	548	if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
idinor	0:dcf3c92487ca	549	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
idinor	0:dcf3c92487ca	550	goto memerr;
idinor	0:dcf3c92487ca	551	}
idinor	0:dcf3c92487ca	552	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	553	/* calculate the checksum of nocopy-data */
idinor	0:dcf3c92487ca	554	chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
idinor	0:dcf3c92487ca	555	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	556	/* reference the non-volatile payload data */
idinor	0:dcf3c92487ca	557	p2->payload = (u8_t*)arg + pos;
idinor	0:dcf3c92487ca	558
idinor	0:dcf3c92487ca	559	/* Second, allocate a pbuf for the headers. */
idinor	0:dcf3c92487ca	560	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
idinor	0:dcf3c92487ca	561	/* If allocation fails, we have to deallocate the data pbuf as
idinor	0:dcf3c92487ca	562	* well. */
idinor	0:dcf3c92487ca	563	pbuf_free(p2);
idinor	0:dcf3c92487ca	564	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for header pbuf\n"));
idinor	0:dcf3c92487ca	565	goto memerr;
idinor	0:dcf3c92487ca	566	}
idinor	0:dcf3c92487ca	567	/* Concatenate the headers and data pbufs together. */
idinor	0:dcf3c92487ca	568	pbuf_cat(p/header/, p2/data/);
idinor	0:dcf3c92487ca	569	}
idinor	0:dcf3c92487ca	570
idinor	0:dcf3c92487ca	571	queuelen += pbuf_clen(p);
idinor	0:dcf3c92487ca	572
idinor	0:dcf3c92487ca	573	/* Now that there are more segments queued, we check again if the
idinor	0:dcf3c92487ca	574	* length of the queue exceeds the configured maximum or
idinor	0:dcf3c92487ca	575	* overflows. */
idinor	0:dcf3c92487ca	576	if ((queuelen > TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
idinor	0:dcf3c92487ca	577	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
idinor	0:dcf3c92487ca	578	pbuf_free(p);
idinor	0:dcf3c92487ca	579	goto memerr;
idinor	0:dcf3c92487ca	580	}
idinor	0:dcf3c92487ca	581
idinor	0:dcf3c92487ca	582	if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
idinor	0:dcf3c92487ca	583	goto memerr;
idinor	0:dcf3c92487ca	584	}
idinor	0:dcf3c92487ca	585	#if TCP_OVERSIZE_DBGCHECK
idinor	0:dcf3c92487ca	586	seg->oversize_left = oversize;
idinor	0:dcf3c92487ca	587	#endif /* TCP_OVERSIZE_DBGCHECK */
idinor	0:dcf3c92487ca	588	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	589	seg->chksum = chksum;
idinor	0:dcf3c92487ca	590	seg->chksum_swapped = chksum_swapped;
idinor	0:dcf3c92487ca	591	seg->flags \|= TF_SEG_DATA_CHECKSUMMED;
idinor	0:dcf3c92487ca	592	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	593	/* Fix dataptr for the nocopy case */
idinor	0:dcf3c92487ca	594	if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
idinor	0:dcf3c92487ca	595	seg->dataptr = (u8_t*)arg + pos;
idinor	0:dcf3c92487ca	596	}
idinor	0:dcf3c92487ca	597
idinor	0:dcf3c92487ca	598	/* first segment of to-be-queued data? */
idinor	0:dcf3c92487ca	599	if (queue == NULL) {
idinor	0:dcf3c92487ca	600	queue = seg;
idinor	0:dcf3c92487ca	601	} else {
idinor	0:dcf3c92487ca	602	/* Attach the segment to the end of the queued segments */
idinor	0:dcf3c92487ca	603	LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
idinor	0:dcf3c92487ca	604	prev_seg->next = seg;
idinor	0:dcf3c92487ca	605	}
idinor	0:dcf3c92487ca	606	/* remember last segment of to-be-queued data for next iteration */
idinor	0:dcf3c92487ca	607	prev_seg = seg;
idinor	0:dcf3c92487ca	608
idinor	0:dcf3c92487ca	609	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
idinor	0:dcf3c92487ca	610	ntohl(seg->tcphdr->seqno),
idinor	0:dcf3c92487ca	611	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
idinor	0:dcf3c92487ca	612
idinor	0:dcf3c92487ca	613	pos += seglen;
idinor	0:dcf3c92487ca	614	}
idinor	0:dcf3c92487ca	615
idinor	0:dcf3c92487ca	616	/*
idinor	0:dcf3c92487ca	617	* All three segmentation phases were successful. We can commit the
idinor	0:dcf3c92487ca	618	* transaction.
idinor	0:dcf3c92487ca	619	*/
idinor	0:dcf3c92487ca	620
idinor	0:dcf3c92487ca	621	/*
idinor	0:dcf3c92487ca	622	* Phase 1: If data has been added to the preallocated tail of
idinor	0:dcf3c92487ca	623	* last_unsent, we update the length fields of the pbuf chain.
idinor	0:dcf3c92487ca	624	*/
idinor	0:dcf3c92487ca	625	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	626	if (oversize_used > 0) {
idinor	0:dcf3c92487ca	627	struct pbuf *p;
idinor	0:dcf3c92487ca	628	/* Bump tot_len of whole chain, len of tail */
idinor	0:dcf3c92487ca	629	for (p = last_unsent->p; p; p = p->next) {
idinor	0:dcf3c92487ca	630	p->tot_len += oversize_used;
idinor	0:dcf3c92487ca	631	if (p->next == NULL) {
idinor	0:dcf3c92487ca	632	TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
idinor	0:dcf3c92487ca	633	p->len += oversize_used;
idinor	0:dcf3c92487ca	634	}
idinor	0:dcf3c92487ca	635	}
idinor	0:dcf3c92487ca	636	last_unsent->len += oversize_used;
idinor	0:dcf3c92487ca	637	#if TCP_OVERSIZE_DBGCHECK
idinor	0:dcf3c92487ca	638	last_unsent->oversize_left -= oversize_used;
idinor	0:dcf3c92487ca	639	#endif /* TCP_OVERSIZE_DBGCHECK */
idinor	0:dcf3c92487ca	640	}
idinor	0:dcf3c92487ca	641	pcb->unsent_oversize = oversize;
idinor	0:dcf3c92487ca	642	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	643
idinor	0:dcf3c92487ca	644	/*
idinor	0:dcf3c92487ca	645	* Phase 2: concat_p can be concatenated onto last_unsent->p
idinor	0:dcf3c92487ca	646	*/
idinor	0:dcf3c92487ca	647	if (concat_p != NULL) {
idinor	0:dcf3c92487ca	648	LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
idinor	0:dcf3c92487ca	649	(last_unsent != NULL));
idinor	0:dcf3c92487ca	650	pbuf_cat(last_unsent->p, concat_p);
idinor	0:dcf3c92487ca	651	last_unsent->len += concat_p->tot_len;
idinor	0:dcf3c92487ca	652	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	653	if (concat_chksummed) {
idinor	0:dcf3c92487ca	654	tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
idinor	0:dcf3c92487ca	655	&last_unsent->chksum_swapped);
idinor	0:dcf3c92487ca	656	last_unsent->flags \|= TF_SEG_DATA_CHECKSUMMED;
idinor	0:dcf3c92487ca	657	}
idinor	0:dcf3c92487ca	658	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	659	}
idinor	0:dcf3c92487ca	660
idinor	0:dcf3c92487ca	661	/*
idinor	0:dcf3c92487ca	662	* Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
idinor	0:dcf3c92487ca	663	* is harmless
idinor	0:dcf3c92487ca	664	*/
idinor	0:dcf3c92487ca	665	if (last_unsent == NULL) {
idinor	0:dcf3c92487ca	666	pcb->unsent = queue;
idinor	0:dcf3c92487ca	667	} else {
idinor	0:dcf3c92487ca	668	last_unsent->next = queue;
idinor	0:dcf3c92487ca	669	}
idinor	0:dcf3c92487ca	670
idinor	0:dcf3c92487ca	671	/*
idinor	0:dcf3c92487ca	672	* Finally update the pcb state.
idinor	0:dcf3c92487ca	673	*/
idinor	0:dcf3c92487ca	674	pcb->snd_lbb += len;
idinor	0:dcf3c92487ca	675	pcb->snd_buf -= len;
idinor	0:dcf3c92487ca	676	pcb->snd_queuelen = queuelen;
idinor	0:dcf3c92487ca	677
idinor	0:dcf3c92487ca	678	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
idinor	0:dcf3c92487ca	679	pcb->snd_queuelen));
idinor	0:dcf3c92487ca	680	if (pcb->snd_queuelen != 0) {
idinor	0:dcf3c92487ca	681	LWIP_ASSERT("tcp_write: valid queue length",
idinor	0:dcf3c92487ca	682	pcb->unacked != NULL \|\| pcb->unsent != NULL);
idinor	0:dcf3c92487ca	683	}
idinor	0:dcf3c92487ca	684
idinor	0:dcf3c92487ca	685	/* Set the PSH flag in the last segment that we enqueued. */
idinor	0:dcf3c92487ca	686	if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
idinor	0:dcf3c92487ca	687	TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
idinor	0:dcf3c92487ca	688	}
idinor	0:dcf3c92487ca	689
idinor	0:dcf3c92487ca	690	return ERR_OK;
idinor	0:dcf3c92487ca	691	memerr:
idinor	0:dcf3c92487ca	692	pcb->flags \|= TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	693	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	694
idinor	0:dcf3c92487ca	695	if (concat_p != NULL) {
idinor	0:dcf3c92487ca	696	pbuf_free(concat_p);
idinor	0:dcf3c92487ca	697	}
idinor	0:dcf3c92487ca	698	if (queue != NULL) {
idinor	0:dcf3c92487ca	699	tcp_segs_free(queue);
idinor	0:dcf3c92487ca	700	}
idinor	0:dcf3c92487ca	701	if (pcb->snd_queuelen != 0) {
idinor	0:dcf3c92487ca	702	LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL \|\|
idinor	0:dcf3c92487ca	703	pcb->unsent != NULL);
idinor	0:dcf3c92487ca	704	}
idinor	0:dcf3c92487ca	705	LWIP_DEBUGF(TCP_QLEN_DEBUG \| LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
idinor	0:dcf3c92487ca	706	return ERR_MEM;
idinor	0:dcf3c92487ca	707	}
idinor	0:dcf3c92487ca	708
idinor	0:dcf3c92487ca	709	/**
idinor	0:dcf3c92487ca	710	* Enqueue TCP options for transmission.
idinor	0:dcf3c92487ca	711	*
idinor	0:dcf3c92487ca	712	* Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
idinor	0:dcf3c92487ca	713	*
idinor	0:dcf3c92487ca	714	* @param pcb Protocol control block for the TCP connection.
idinor	0:dcf3c92487ca	715	* @param flags TCP header flags to set in the outgoing segment.
idinor	0:dcf3c92487ca	716	* @param optdata pointer to TCP options, or NULL.
idinor	0:dcf3c92487ca	717	* @param optlen length of TCP options in bytes.
idinor	0:dcf3c92487ca	718	*/
idinor	0:dcf3c92487ca	719	err_t
idinor	0:dcf3c92487ca	720	tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
idinor	0:dcf3c92487ca	721	{
idinor	0:dcf3c92487ca	722	struct pbuf *p;
idinor	0:dcf3c92487ca	723	struct tcp_seg *seg;
idinor	0:dcf3c92487ca	724	u8_t optflags = 0;
idinor	0:dcf3c92487ca	725	u8_t optlen = 0;
idinor	0:dcf3c92487ca	726
idinor	0:dcf3c92487ca	727	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	728
idinor	0:dcf3c92487ca	729	LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
idinor	0:dcf3c92487ca	730	(flags & (TCP_SYN \| TCP_FIN)) != 0);
idinor	0:dcf3c92487ca	731
idinor	0:dcf3c92487ca	732	/* check for configured max queuelen and possible overflow */
idinor	0:dcf3c92487ca	733	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
idinor	0:dcf3c92487ca	734	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
idinor	0:dcf3c92487ca	735	pcb->snd_queuelen, TCP_SND_QUEUELEN));
idinor	0:dcf3c92487ca	736	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	737	pcb->flags \|= TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	738	return ERR_MEM;
idinor	0:dcf3c92487ca	739	}
idinor	0:dcf3c92487ca	740
idinor	0:dcf3c92487ca	741	if (flags & TCP_SYN) {
idinor	0:dcf3c92487ca	742	optflags = TF_SEG_OPTS_MSS;
idinor	0:dcf3c92487ca	743	}
idinor	0:dcf3c92487ca	744	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	745	if ((pcb->flags & TF_TIMESTAMP)) {
idinor	0:dcf3c92487ca	746	optflags \|= TF_SEG_OPTS_TS;
idinor	0:dcf3c92487ca	747	}
idinor	0:dcf3c92487ca	748	#endif /* LWIP_TCP_TIMESTAMPS */
idinor	0:dcf3c92487ca	749	optlen = LWIP_TCP_OPT_LENGTH(optflags);
idinor	0:dcf3c92487ca	750
idinor	0:dcf3c92487ca	751	/* tcp_enqueue_flags is always called with either SYN or FIN in flags.
idinor	0:dcf3c92487ca	752	* We need one available snd_buf byte to do that.
idinor	0:dcf3c92487ca	753	* This means we can't send FIN while snd_buf==0. A better fix would be to
idinor	0:dcf3c92487ca	754	* not include SYN and FIN sequence numbers in the snd_buf count. */
idinor	0:dcf3c92487ca	755	if (pcb->snd_buf == 0) {
idinor	0:dcf3c92487ca	756	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: no send buffer available\n"));
idinor	0:dcf3c92487ca	757	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	758	return ERR_MEM;
idinor	0:dcf3c92487ca	759	}
idinor	0:dcf3c92487ca	760
idinor	0:dcf3c92487ca	761	/* Allocate pbuf with room for TCP header + options */
idinor	0:dcf3c92487ca	762	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
idinor	0:dcf3c92487ca	763	pcb->flags \|= TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	764	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	765	return ERR_MEM;
idinor	0:dcf3c92487ca	766	}
idinor	0:dcf3c92487ca	767	LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
idinor	0:dcf3c92487ca	768	(p->len >= optlen));
idinor	0:dcf3c92487ca	769
idinor	0:dcf3c92487ca	770	/* Allocate memory for tcp_seg, and fill in fields. */
idinor	0:dcf3c92487ca	771	if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
idinor	0:dcf3c92487ca	772	pcb->flags \|= TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	773	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	774	return ERR_MEM;
idinor	0:dcf3c92487ca	775	}
idinor	0:dcf3c92487ca	776	LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
idinor	0:dcf3c92487ca	777
idinor	0:dcf3c92487ca	778	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE,
idinor	0:dcf3c92487ca	779	("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
idinor	0:dcf3c92487ca	780	ntohl(seg->tcphdr->seqno),
idinor	0:dcf3c92487ca	781	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
idinor	0:dcf3c92487ca	782	(u16_t)flags));
idinor	0:dcf3c92487ca	783
idinor	0:dcf3c92487ca	784	/* Now append seg to pcb->unsent queue */
idinor	0:dcf3c92487ca	785	if (pcb->unsent == NULL) {
idinor	0:dcf3c92487ca	786	pcb->unsent = seg;
idinor	0:dcf3c92487ca	787	} else {
idinor	0:dcf3c92487ca	788	struct tcp_seg *useg;
idinor	0:dcf3c92487ca	789	for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
idinor	0:dcf3c92487ca	790	useg->next = seg;
idinor	0:dcf3c92487ca	791	}
idinor	0:dcf3c92487ca	792	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	793	/* The new unsent tail has no space */
idinor	0:dcf3c92487ca	794	pcb->unsent_oversize = 0;
idinor	0:dcf3c92487ca	795	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	796
idinor	0:dcf3c92487ca	797	/* SYN and FIN bump the sequence number */
idinor	0:dcf3c92487ca	798	if ((flags & TCP_SYN) \|\| (flags & TCP_FIN)) {
idinor	0:dcf3c92487ca	799	pcb->snd_lbb++;
idinor	0:dcf3c92487ca	800	/* optlen does not influence snd_buf */
idinor	0:dcf3c92487ca	801	pcb->snd_buf--;
idinor	0:dcf3c92487ca	802	}
idinor	0:dcf3c92487ca	803	if (flags & TCP_FIN) {
idinor	0:dcf3c92487ca	804	pcb->flags \|= TF_FIN;
idinor	0:dcf3c92487ca	805	}
idinor	0:dcf3c92487ca	806
idinor	0:dcf3c92487ca	807	/* update number of segments on the queues */
idinor	0:dcf3c92487ca	808	pcb->snd_queuelen += pbuf_clen(seg->p);
idinor	0:dcf3c92487ca	809	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
idinor	0:dcf3c92487ca	810	if (pcb->snd_queuelen != 0) {
idinor	0:dcf3c92487ca	811	LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
idinor	0:dcf3c92487ca	812	pcb->unacked != NULL \|\| pcb->unsent != NULL);
idinor	0:dcf3c92487ca	813	}
idinor	0:dcf3c92487ca	814
idinor	0:dcf3c92487ca	815	return ERR_OK;
idinor	0:dcf3c92487ca	816	}
idinor	0:dcf3c92487ca	817
idinor	0:dcf3c92487ca	818
idinor	0:dcf3c92487ca	819	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	820	/* Build a timestamp option (12 bytes long) at the specified options pointer)
idinor	0:dcf3c92487ca	821	*
idinor	0:dcf3c92487ca	822	* @param pcb tcp_pcb
idinor	0:dcf3c92487ca	823	* @param opts option pointer where to store the timestamp option
idinor	0:dcf3c92487ca	824	*/
idinor	0:dcf3c92487ca	825	static void
idinor	0:dcf3c92487ca	826	tcp_build_timestamp_option(struct tcp_pcb pcb, u32_t opts)
idinor	0:dcf3c92487ca	827	{
idinor	0:dcf3c92487ca	828	/* Pad with two NOP options to make everything nicely aligned */
idinor	0:dcf3c92487ca	829	opts[0] = PP_HTONL(0x0101080A);
idinor	0:dcf3c92487ca	830	opts[1] = htonl(sys_now());
idinor	0:dcf3c92487ca	831	opts[2] = htonl(pcb->ts_recent);
idinor	0:dcf3c92487ca	832	}
idinor	0:dcf3c92487ca	833	#endif
idinor	0:dcf3c92487ca	834
idinor	0:dcf3c92487ca	835	/** Send an ACK without data.
idinor	0:dcf3c92487ca	836	*
idinor	0:dcf3c92487ca	837	* @param pcb Protocol control block for the TCP connection to send the ACK
idinor	0:dcf3c92487ca	838	*/
idinor	0:dcf3c92487ca	839	err_t
idinor	0:dcf3c92487ca	840	tcp_send_empty_ack(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	841	{
idinor	0:dcf3c92487ca	842	struct pbuf *p;
idinor	0:dcf3c92487ca	843	struct tcp_hdr *tcphdr;
idinor	0:dcf3c92487ca	844	u8_t optlen = 0;
idinor	0:dcf3c92487ca	845
idinor	0:dcf3c92487ca	846	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	847	if (pcb->flags & TF_TIMESTAMP) {
idinor	0:dcf3c92487ca	848	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
idinor	0:dcf3c92487ca	849	}
idinor	0:dcf3c92487ca	850	#endif
idinor	0:dcf3c92487ca	851
idinor	0:dcf3c92487ca	852	p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
idinor	0:dcf3c92487ca	853	if (p == NULL) {
idinor	0:dcf3c92487ca	854	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
idinor	0:dcf3c92487ca	855	return ERR_BUF;
idinor	0:dcf3c92487ca	856	}
idinor	0:dcf3c92487ca	857	tcphdr = (struct tcp_hdr *)p->payload;
idinor	0:dcf3c92487ca	858	LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
idinor	0:dcf3c92487ca	859	("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
idinor	0:dcf3c92487ca	860	/* remove ACK flags from the PCB, as we send an empty ACK now */
idinor	0:dcf3c92487ca	861	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
idinor	0:dcf3c92487ca	862
idinor	0:dcf3c92487ca	863	/* NB. MSS option is only sent on SYNs, so ignore it here */
idinor	0:dcf3c92487ca	864	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	865	pcb->ts_lastacksent = pcb->rcv_nxt;
idinor	0:dcf3c92487ca	866
idinor	0:dcf3c92487ca	867	if (pcb->flags & TF_TIMESTAMP) {
idinor	0:dcf3c92487ca	868	tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
idinor	0:dcf3c92487ca	869	}
idinor	0:dcf3c92487ca	870	#endif
idinor	0:dcf3c92487ca	871
idinor	0:dcf3c92487ca	872	#if CHECKSUM_GEN_TCP
idinor	0:dcf3c92487ca	873	tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
idinor	0:dcf3c92487ca	874	IP_PROTO_TCP, p->tot_len);
idinor	0:dcf3c92487ca	875	#endif
idinor	0:dcf3c92487ca	876	#if LWIP_NETIF_HWADDRHINT
idinor	0:dcf3c92487ca	877	ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
idinor	0:dcf3c92487ca	878	IP_PROTO_TCP, &(pcb->addr_hint));
idinor	0:dcf3c92487ca	879	#else /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	880	ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
idinor	0:dcf3c92487ca	881	IP_PROTO_TCP);
idinor	0:dcf3c92487ca	882	#endif /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	883	pbuf_free(p);
idinor	0:dcf3c92487ca	884
idinor	0:dcf3c92487ca	885	return ERR_OK;
idinor	0:dcf3c92487ca	886	}
idinor	0:dcf3c92487ca	887
idinor	0:dcf3c92487ca	888	/**
idinor	0:dcf3c92487ca	889	* Find out what we can send and send it
idinor	0:dcf3c92487ca	890	*
idinor	0:dcf3c92487ca	891	* @param pcb Protocol control block for the TCP connection to send data
idinor	0:dcf3c92487ca	892	* @return ERR_OK if data has been sent or nothing to send
idinor	0:dcf3c92487ca	893	* another err_t on error
idinor	0:dcf3c92487ca	894	*/
idinor	0:dcf3c92487ca	895	err_t
idinor	0:dcf3c92487ca	896	tcp_output(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	897	{
idinor	0:dcf3c92487ca	898	struct tcp_seg seg, useg;
idinor	0:dcf3c92487ca	899	u32_t wnd, snd_nxt;
idinor	0:dcf3c92487ca	900	#if TCP_CWND_DEBUG
idinor	0:dcf3c92487ca	901	s16_t i = 0;
idinor	0:dcf3c92487ca	902	#endif /* TCP_CWND_DEBUG */
idinor	0:dcf3c92487ca	903
idinor	0:dcf3c92487ca	904	/* First, check if we are invoked by the TCP input processing
idinor	0:dcf3c92487ca	905	code. If so, we do not output anything. Instead, we rely on the
idinor	0:dcf3c92487ca	906	input processing code to call us when input processing is done
idinor	0:dcf3c92487ca	907	with. */
idinor	0:dcf3c92487ca	908	if (tcp_input_pcb == pcb) {
idinor	0:dcf3c92487ca	909	return ERR_OK;
idinor	0:dcf3c92487ca	910	}
idinor	0:dcf3c92487ca	911
idinor	0:dcf3c92487ca	912	wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
idinor	0:dcf3c92487ca	913
idinor	0:dcf3c92487ca	914	seg = pcb->unsent;
idinor	0:dcf3c92487ca	915
idinor	0:dcf3c92487ca	916	/* If the TF_ACK_NOW flag is set and no data will be sent (either
idinor	0:dcf3c92487ca	917	* because the ->unsent queue is empty or because the window does
idinor	0:dcf3c92487ca	918	* not allow it), construct an empty ACK segment and send it.
idinor	0:dcf3c92487ca	919	*
idinor	0:dcf3c92487ca	920	* If data is to be sent, we will just piggyback the ACK (see below).
idinor	0:dcf3c92487ca	921	*/
idinor	0:dcf3c92487ca	922	if (pcb->flags & TF_ACK_NOW &&
idinor	0:dcf3c92487ca	923	(seg == NULL \|\|
idinor	0:dcf3c92487ca	924	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
idinor	0:dcf3c92487ca	925	return tcp_send_empty_ack(pcb);
idinor	0:dcf3c92487ca	926	}
idinor	0:dcf3c92487ca	927
idinor	0:dcf3c92487ca	928	/* useg should point to last segment on unacked queue */
idinor	0:dcf3c92487ca	929	useg = pcb->unacked;
idinor	0:dcf3c92487ca	930	if (useg != NULL) {
idinor	0:dcf3c92487ca	931	for (; useg->next != NULL; useg = useg->next);
idinor	0:dcf3c92487ca	932	}
idinor	0:dcf3c92487ca	933
idinor	0:dcf3c92487ca	934	#if TCP_OUTPUT_DEBUG
idinor	0:dcf3c92487ca	935	if (seg == NULL) {
idinor	0:dcf3c92487ca	936	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
idinor	0:dcf3c92487ca	937	(void*)pcb->unsent));
idinor	0:dcf3c92487ca	938	}
idinor	0:dcf3c92487ca	939	#endif /* TCP_OUTPUT_DEBUG */
idinor	0:dcf3c92487ca	940	#if TCP_CWND_DEBUG
idinor	0:dcf3c92487ca	941	if (seg == NULL) {
idinor	0:dcf3c92487ca	942	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
idinor	0:dcf3c92487ca	943	", cwnd %"U16_F", wnd %"U32_F
idinor	0:dcf3c92487ca	944	", seg == NULL, ack %"U32_F"\n",
idinor	0:dcf3c92487ca	945	pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
idinor	0:dcf3c92487ca	946	} else {
idinor	0:dcf3c92487ca	947	LWIP_DEBUGF(TCP_CWND_DEBUG,
idinor	0:dcf3c92487ca	948	("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
idinor	0:dcf3c92487ca	949	", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
idinor	0:dcf3c92487ca	950	pcb->snd_wnd, pcb->cwnd, wnd,
idinor	0:dcf3c92487ca	951	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
idinor	0:dcf3c92487ca	952	ntohl(seg->tcphdr->seqno), pcb->lastack));
idinor	0:dcf3c92487ca	953	}
idinor	0:dcf3c92487ca	954	#endif /* TCP_CWND_DEBUG */
idinor	0:dcf3c92487ca	955	/* data available and window allows it to be sent? */
idinor	0:dcf3c92487ca	956	while (seg != NULL &&
idinor	0:dcf3c92487ca	957	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
idinor	0:dcf3c92487ca	958	LWIP_ASSERT("RST not expected here!",
idinor	0:dcf3c92487ca	959	(TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
idinor	0:dcf3c92487ca	960	/* Stop sending if the nagle algorithm would prevent it
idinor	0:dcf3c92487ca	961	* Don't stop:
idinor	0:dcf3c92487ca	962	* - if tcp_write had a memory error before (prevent delayed ACK timeout) or
idinor	0:dcf3c92487ca	963	* - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
idinor	0:dcf3c92487ca	964	* either seg->next != NULL or pcb->unacked == NULL;
idinor	0:dcf3c92487ca	965	* RST is no sent using tcp_write/tcp_output.
idinor	0:dcf3c92487ca	966	*/
idinor	0:dcf3c92487ca	967	if((tcp_do_output_nagle(pcb) == 0) &&
idinor	0:dcf3c92487ca	968	((pcb->flags & (TF_NAGLEMEMERR \| TF_FIN)) == 0)){
idinor	0:dcf3c92487ca	969	break;
idinor	0:dcf3c92487ca	970	}
idinor	0:dcf3c92487ca	971	#if TCP_CWND_DEBUG
idinor	0:dcf3c92487ca	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",
idinor	0:dcf3c92487ca	973	pcb->snd_wnd, pcb->cwnd, wnd,
idinor	0:dcf3c92487ca	974	ntohl(seg->tcphdr->seqno) + seg->len -
idinor	0:dcf3c92487ca	975	pcb->lastack,
idinor	0:dcf3c92487ca	976	ntohl(seg->tcphdr->seqno), pcb->lastack, i));
idinor	0:dcf3c92487ca	977	++i;
idinor	0:dcf3c92487ca	978	#endif /* TCP_CWND_DEBUG */
idinor	0:dcf3c92487ca	979
idinor	0:dcf3c92487ca	980	pcb->unsent = seg->next;
idinor	0:dcf3c92487ca	981
idinor	0:dcf3c92487ca	982	if (pcb->state != SYN_SENT) {
idinor	0:dcf3c92487ca	983	TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
idinor	0:dcf3c92487ca	984	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
idinor	0:dcf3c92487ca	985	}
idinor	0:dcf3c92487ca	986
idinor	0:dcf3c92487ca	987	tcp_output_segment(seg, pcb);
idinor	0:dcf3c92487ca	988
idinor	0:dcf3c92487ca	989	snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
idinor	0:dcf3c92487ca	990
idinor	0:dcf3c92487ca	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
idinor	0:dcf3c92487ca	992	pcb->snd_nxt, ntohl(seg->tcphdr->seqno), TCP_TCPLEN(seg), snd_nxt));
idinor	0:dcf3c92487ca	993
idinor	0:dcf3c92487ca	994	if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
idinor	0:dcf3c92487ca	995	pcb->snd_nxt = snd_nxt;
idinor	0:dcf3c92487ca	996	}
idinor	0:dcf3c92487ca	997	/* put segment on unacknowledged list if length > 0 */
idinor	0:dcf3c92487ca	998	if (TCP_TCPLEN(seg) > 0) {
idinor	0:dcf3c92487ca	999	seg->next = NULL;
idinor	0:dcf3c92487ca	1000	/* unacked list is empty? */
idinor	0:dcf3c92487ca	1001	if (pcb->unacked == NULL) {
idinor	0:dcf3c92487ca	1002	pcb->unacked = seg;
idinor	0:dcf3c92487ca	1003	useg = seg;
idinor	0:dcf3c92487ca	1004	/* unacked list is not empty? */
idinor	0:dcf3c92487ca	1005	} else {
idinor	0:dcf3c92487ca	1006	/* In the case of fast retransmit, the packet should not go to the tail
idinor	0:dcf3c92487ca	1007	* of the unacked queue, but rather somewhere before it. We need to check for
idinor	0:dcf3c92487ca	1008	* this case. -STJ Jul 27, 2004 */
idinor	0:dcf3c92487ca	1009	if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
idinor	0:dcf3c92487ca	1010	/* add segment to before tail of unacked list, keeping the list sorted */
idinor	0:dcf3c92487ca	1011	struct tcp_seg **cur_seg = &(pcb->unacked);
idinor	0:dcf3c92487ca	1012	while (*cur_seg &&
idinor	0:dcf3c92487ca	1013	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
idinor	0:dcf3c92487ca	1014	cur_seg = &((*cur_seg)->next );
idinor	0:dcf3c92487ca	1015	}
idinor	0:dcf3c92487ca	1016	seg->next = (*cur_seg);
idinor	0:dcf3c92487ca	1017	(*cur_seg) = seg;
idinor	0:dcf3c92487ca	1018	} else {
idinor	0:dcf3c92487ca	1019	/* add segment to tail of unacked list */
idinor	0:dcf3c92487ca	1020	useg->next = seg;
idinor	0:dcf3c92487ca	1021	useg = useg->next;
idinor	0:dcf3c92487ca	1022	}
idinor	0:dcf3c92487ca	1023	}
idinor	0:dcf3c92487ca	1024	/* do not queue empty segments on the unacked list */
idinor	0:dcf3c92487ca	1025	} else {
idinor	0:dcf3c92487ca	1026	tcp_seg_free(seg);
idinor	0:dcf3c92487ca	1027	}
idinor	0:dcf3c92487ca	1028	seg = pcb->unsent;
idinor	0:dcf3c92487ca	1029	}
idinor	0:dcf3c92487ca	1030	#if TCP_OVERSIZE
idinor	0:dcf3c92487ca	1031	if (pcb->unsent == NULL) {
idinor	0:dcf3c92487ca	1032	/* last unsent has been removed, reset unsent_oversize */
idinor	0:dcf3c92487ca	1033	pcb->unsent_oversize = 0;
idinor	0:dcf3c92487ca	1034	}
idinor	0:dcf3c92487ca	1035	#endif /* TCP_OVERSIZE */
idinor	0:dcf3c92487ca	1036
idinor	0:dcf3c92487ca	1037	if (seg != NULL && pcb->persist_backoff == 0 &&
idinor	0:dcf3c92487ca	1038	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) {
idinor	0:dcf3c92487ca	1039	/* prepare for persist timer */
idinor	0:dcf3c92487ca	1040	pcb->persist_cnt = 0;
idinor	0:dcf3c92487ca	1041	pcb->persist_backoff = 1;
idinor	0:dcf3c92487ca	1042	}
idinor	0:dcf3c92487ca	1043
idinor	0:dcf3c92487ca	1044	pcb->flags &= ~TF_NAGLEMEMERR;
idinor	0:dcf3c92487ca	1045	return ERR_OK;
idinor	0:dcf3c92487ca	1046	}
idinor	0:dcf3c92487ca	1047
idinor	0:dcf3c92487ca	1048	/**
idinor	0:dcf3c92487ca	1049	* Called by tcp_output() to actually send a TCP segment over IP.
idinor	0:dcf3c92487ca	1050	*
idinor	0:dcf3c92487ca	1051	* @param seg the tcp_seg to send
idinor	0:dcf3c92487ca	1052	* @param pcb the tcp_pcb for the TCP connection used to send the segment
idinor	0:dcf3c92487ca	1053	*/
idinor	0:dcf3c92487ca	1054	static void
idinor	0:dcf3c92487ca	1055	tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb)
idinor	0:dcf3c92487ca	1056	{
idinor	0:dcf3c92487ca	1057	u16_t len;
idinor	0:dcf3c92487ca	1058	struct netif *netif;
idinor	0:dcf3c92487ca	1059	u32_t *opts;
idinor	0:dcf3c92487ca	1060
idinor	0:dcf3c92487ca	1061	/** @bug Exclude retransmitted segments from this count. */
idinor	0:dcf3c92487ca	1062	snmp_inc_tcpoutsegs();
idinor	0:dcf3c92487ca	1063
idinor	0:dcf3c92487ca	1064	/* The TCP header has already been constructed, but the ackno and
idinor	0:dcf3c92487ca	1065	wnd fields remain. */
idinor	0:dcf3c92487ca	1066	seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
idinor	0:dcf3c92487ca	1067
idinor	0:dcf3c92487ca	1068	/* advertise our receive window size in this TCP segment */
idinor	0:dcf3c92487ca	1069	seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
idinor	0:dcf3c92487ca	1070
idinor	0:dcf3c92487ca	1071	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
idinor	0:dcf3c92487ca	1072
idinor	0:dcf3c92487ca	1073	/* Add any requested options. NB MSS option is only set on SYN
idinor	0:dcf3c92487ca	1074	packets, so ignore it here */
idinor	0:dcf3c92487ca	1075	LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
idinor	0:dcf3c92487ca	1076	opts = (u32_t )(void )(seg->tcphdr + 1);
idinor	0:dcf3c92487ca	1077	if (seg->flags & TF_SEG_OPTS_MSS) {
idinor	0:dcf3c92487ca	1078	TCP_BUILD_MSS_OPTION(*opts);
idinor	0:dcf3c92487ca	1079	opts += 1;
idinor	0:dcf3c92487ca	1080	}
idinor	0:dcf3c92487ca	1081	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	1082	pcb->ts_lastacksent = pcb->rcv_nxt;
idinor	0:dcf3c92487ca	1083
idinor	0:dcf3c92487ca	1084	if (seg->flags & TF_SEG_OPTS_TS) {
idinor	0:dcf3c92487ca	1085	tcp_build_timestamp_option(pcb, opts);
idinor	0:dcf3c92487ca	1086	opts += 3;
idinor	0:dcf3c92487ca	1087	}
idinor	0:dcf3c92487ca	1088	#endif
idinor	0:dcf3c92487ca	1089
idinor	0:dcf3c92487ca	1090	/* If we don't have a local IP address, we get one by
idinor	0:dcf3c92487ca	1091	calling ip_route(). */
idinor	0:dcf3c92487ca	1092	if (ip_addr_isany(&(pcb->local_ip))) {
idinor	0:dcf3c92487ca	1093	netif = ip_route(&(pcb->remote_ip));
idinor	0:dcf3c92487ca	1094	if (netif == NULL) {
idinor	0:dcf3c92487ca	1095	return;
idinor	0:dcf3c92487ca	1096	}
idinor	0:dcf3c92487ca	1097	ip_addr_copy(pcb->local_ip, netif->ip_addr);
idinor	0:dcf3c92487ca	1098	}
idinor	0:dcf3c92487ca	1099
idinor	0:dcf3c92487ca	1100	/* Set retransmission timer running if it is not currently enabled */
idinor	0:dcf3c92487ca	1101	if(pcb->rtime == -1) {
idinor	0:dcf3c92487ca	1102	pcb->rtime = 0;
idinor	0:dcf3c92487ca	1103	}
idinor	0:dcf3c92487ca	1104
idinor	0:dcf3c92487ca	1105	if (pcb->rttest == 0) {
idinor	0:dcf3c92487ca	1106	pcb->rttest = tcp_ticks;
idinor	0:dcf3c92487ca	1107	pcb->rtseq = ntohl(seg->tcphdr->seqno);
idinor	0:dcf3c92487ca	1108
idinor	0:dcf3c92487ca	1109	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
idinor	0:dcf3c92487ca	1110	}
idinor	0:dcf3c92487ca	1111	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
idinor	0:dcf3c92487ca	1112	htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
idinor	0:dcf3c92487ca	1113	seg->len));
idinor	0:dcf3c92487ca	1114
idinor	0:dcf3c92487ca	1115	len = (u16_t)((u8_t )seg->tcphdr - (u8_t )seg->p->payload);
idinor	0:dcf3c92487ca	1116
idinor	0:dcf3c92487ca	1117	seg->p->len -= len;
idinor	0:dcf3c92487ca	1118	seg->p->tot_len -= len;
idinor	0:dcf3c92487ca	1119
idinor	0:dcf3c92487ca	1120	seg->p->payload = seg->tcphdr;
idinor	0:dcf3c92487ca	1121
idinor	0:dcf3c92487ca	1122	seg->tcphdr->chksum = 0;
idinor	0:dcf3c92487ca	1123	#if CHECKSUM_GEN_TCP
idinor	0:dcf3c92487ca	1124	#if TCP_CHECKSUM_ON_COPY
idinor	0:dcf3c92487ca	1125	{
idinor	0:dcf3c92487ca	1126	u32_t acc;
idinor	0:dcf3c92487ca	1127	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
idinor	0:dcf3c92487ca	1128	u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
idinor	0:dcf3c92487ca	1129	&(pcb->remote_ip),
idinor	0:dcf3c92487ca	1130	IP_PROTO_TCP, seg->p->tot_len);
idinor	0:dcf3c92487ca	1131	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
idinor	0:dcf3c92487ca	1132	if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
idinor	0:dcf3c92487ca	1133	LWIP_ASSERT("data included but not checksummed",
idinor	0:dcf3c92487ca	1134	seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
idinor	0:dcf3c92487ca	1135	}
idinor	0:dcf3c92487ca	1136
idinor	0:dcf3c92487ca	1137	/* rebuild TCP header checksum (TCP header changes for retransmissions!) */
idinor	0:dcf3c92487ca	1138	acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
idinor	0:dcf3c92487ca	1139	&(pcb->remote_ip),
idinor	0:dcf3c92487ca	1140	IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
idinor	0:dcf3c92487ca	1141	/* add payload checksum */
idinor	0:dcf3c92487ca	1142	if (seg->chksum_swapped) {
idinor	0:dcf3c92487ca	1143	seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
idinor	0:dcf3c92487ca	1144	seg->chksum_swapped = 0;
idinor	0:dcf3c92487ca	1145	}
idinor	0:dcf3c92487ca	1146	acc += (u16_t)~(seg->chksum);
idinor	0:dcf3c92487ca	1147	seg->tcphdr->chksum = FOLD_U32T(acc);
idinor	0:dcf3c92487ca	1148	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
idinor	0:dcf3c92487ca	1149	if (chksum_slow != seg->tcphdr->chksum) {
idinor	0:dcf3c92487ca	1150	LWIP_DEBUGF(TCP_DEBUG \| LWIP_DBG_LEVEL_WARNING,
idinor	0:dcf3c92487ca	1151	("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
idinor	0:dcf3c92487ca	1152	seg->tcphdr->chksum, chksum_slow));
idinor	0:dcf3c92487ca	1153	seg->tcphdr->chksum = chksum_slow;
idinor	0:dcf3c92487ca	1154	}
idinor	0:dcf3c92487ca	1155	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
idinor	0:dcf3c92487ca	1156	}
idinor	0:dcf3c92487ca	1157	#else /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	1158	seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
idinor	0:dcf3c92487ca	1159	&(pcb->remote_ip),
idinor	0:dcf3c92487ca	1160	IP_PROTO_TCP, seg->p->tot_len);
idinor	0:dcf3c92487ca	1161	#endif /* TCP_CHECKSUM_ON_COPY */
idinor	0:dcf3c92487ca	1162	#endif /* CHECKSUM_GEN_TCP */
idinor	0:dcf3c92487ca	1163	TCP_STATS_INC(tcp.xmit);
idinor	0:dcf3c92487ca	1164
idinor	0:dcf3c92487ca	1165	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: Before ip_out seqno = %"U32_F"\n",
idinor	0:dcf3c92487ca	1166	htonl(seg->tcphdr->seqno))); //DG
idinor	0:dcf3c92487ca	1167
idinor	0:dcf3c92487ca	1168	#if LWIP_NETIF_HWADDRHINT
idinor	0:dcf3c92487ca	1169	ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
idinor	0:dcf3c92487ca	1170	IP_PROTO_TCP, &(pcb->addr_hint));
idinor	0:dcf3c92487ca	1171	#else /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	1172	ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
idinor	0:dcf3c92487ca	1173	IP_PROTO_TCP);
idinor	0:dcf3c92487ca	1174	#endif /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	1175
idinor	0:dcf3c92487ca	1176	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: After ip_out seqno = %"U32_F"\n",
idinor	0:dcf3c92487ca	1177	htonl(seg->tcphdr->seqno))); //DG
idinor	0:dcf3c92487ca	1178
idinor	0:dcf3c92487ca	1179
idinor	0:dcf3c92487ca	1180	}
idinor	0:dcf3c92487ca	1181
idinor	0:dcf3c92487ca	1182	/**
idinor	0:dcf3c92487ca	1183	* Send a TCP RESET packet (empty segment with RST flag set) either to
idinor	0:dcf3c92487ca	1184	* abort a connection or to show that there is no matching local connection
idinor	0:dcf3c92487ca	1185	* for a received segment.
idinor	0:dcf3c92487ca	1186	*
idinor	0:dcf3c92487ca	1187	* Called by tcp_abort() (to abort a local connection), tcp_input() (if no
idinor	0:dcf3c92487ca	1188	* matching local pcb was found), tcp_listen_input() (if incoming segment
idinor	0:dcf3c92487ca	1189	* has ACK flag set) and tcp_process() (received segment in the wrong state)
idinor	0:dcf3c92487ca	1190	*
idinor	0:dcf3c92487ca	1191	* Since a RST segment is in most cases not sent for an active connection,
idinor	0:dcf3c92487ca	1192	* tcp_rst() has a number of arguments that are taken from a tcp_pcb for
idinor	0:dcf3c92487ca	1193	* most other segment output functions.
idinor	0:dcf3c92487ca	1194	*
idinor	0:dcf3c92487ca	1195	* @param seqno the sequence number to use for the outgoing segment
idinor	0:dcf3c92487ca	1196	* @param ackno the acknowledge number to use for the outgoing segment
idinor	0:dcf3c92487ca	1197	* @param local_ip the local IP address to send the segment from
idinor	0:dcf3c92487ca	1198	* @param remote_ip the remote IP address to send the segment to
idinor	0:dcf3c92487ca	1199	* @param local_port the local TCP port to send the segment from
idinor	0:dcf3c92487ca	1200	* @param remote_port the remote TCP port to send the segment to
idinor	0:dcf3c92487ca	1201	*/
idinor	0:dcf3c92487ca	1202	void
idinor	0:dcf3c92487ca	1203	tcp_rst(u32_t seqno, u32_t ackno,
idinor	0:dcf3c92487ca	1204	ip_addr_t local_ip, ip_addr_t remote_ip,
idinor	0:dcf3c92487ca	1205	u16_t local_port, u16_t remote_port)
idinor	0:dcf3c92487ca	1206	{
idinor	0:dcf3c92487ca	1207	struct pbuf *p;
idinor	0:dcf3c92487ca	1208	struct tcp_hdr *tcphdr;
idinor	0:dcf3c92487ca	1209	p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
idinor	0:dcf3c92487ca	1210	if (p == NULL) {
idinor	0:dcf3c92487ca	1211	LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
idinor	0:dcf3c92487ca	1212	return;
idinor	0:dcf3c92487ca	1213	}
idinor	0:dcf3c92487ca	1214	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
idinor	0:dcf3c92487ca	1215	(p->len >= sizeof(struct tcp_hdr)));
idinor	0:dcf3c92487ca	1216
idinor	0:dcf3c92487ca	1217	tcphdr = (struct tcp_hdr *)p->payload;
idinor	0:dcf3c92487ca	1218	tcphdr->src = htons(local_port);
idinor	0:dcf3c92487ca	1219	tcphdr->dest = htons(remote_port);
idinor	0:dcf3c92487ca	1220	tcphdr->seqno = htonl(seqno);
idinor	0:dcf3c92487ca	1221	tcphdr->ackno = htonl(ackno);
idinor	0:dcf3c92487ca	1222	TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST \| TCP_ACK);
idinor	0:dcf3c92487ca	1223	tcphdr->wnd = PP_HTONS(TCP_WND);
idinor	0:dcf3c92487ca	1224	tcphdr->chksum = 0;
idinor	0:dcf3c92487ca	1225	tcphdr->urgp = 0;
idinor	0:dcf3c92487ca	1226
idinor	0:dcf3c92487ca	1227	#if CHECKSUM_GEN_TCP
idinor	0:dcf3c92487ca	1228	tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
idinor	0:dcf3c92487ca	1229	IP_PROTO_TCP, p->tot_len);
idinor	0:dcf3c92487ca	1230	#endif
idinor	0:dcf3c92487ca	1231	TCP_STATS_INC(tcp.xmit);
idinor	0:dcf3c92487ca	1232	snmp_inc_tcpoutrsts();
idinor	0:dcf3c92487ca	1233	/* Send output with hardcoded TTL since we have no access to the pcb */
idinor	0:dcf3c92487ca	1234	ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
idinor	0:dcf3c92487ca	1235	pbuf_free(p);
idinor	0:dcf3c92487ca	1236	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
idinor	0:dcf3c92487ca	1237	}
idinor	0:dcf3c92487ca	1238
idinor	0:dcf3c92487ca	1239	/**
idinor	0:dcf3c92487ca	1240	* Requeue all unacked segments for retransmission
idinor	0:dcf3c92487ca	1241	*
idinor	0:dcf3c92487ca	1242	* Called by tcp_slowtmr() for slow retransmission.
idinor	0:dcf3c92487ca	1243	*
idinor	0:dcf3c92487ca	1244	* @param pcb the tcp_pcb for which to re-enqueue all unacked segments
idinor	0:dcf3c92487ca	1245	*/
idinor	0:dcf3c92487ca	1246	void
idinor	0:dcf3c92487ca	1247	tcp_rexmit_rto(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	1248	{
idinor	0:dcf3c92487ca	1249	struct tcp_seg *seg;
idinor	0:dcf3c92487ca	1250
idinor	0:dcf3c92487ca	1251	if (pcb->unacked == NULL) {
idinor	0:dcf3c92487ca	1252	return;
idinor	0:dcf3c92487ca	1253	}
idinor	0:dcf3c92487ca	1254
idinor	0:dcf3c92487ca	1255	/* Move all unacked segments to the head of the unsent queue */
idinor	0:dcf3c92487ca	1256	for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
idinor	0:dcf3c92487ca	1257	/* concatenate unsent queue after unacked queue */
idinor	0:dcf3c92487ca	1258	seg->next = pcb->unsent;
idinor	0:dcf3c92487ca	1259	/* unsent queue is the concatenated queue (of unacked, unsent) */
idinor	0:dcf3c92487ca	1260	pcb->unsent = pcb->unacked;
idinor	0:dcf3c92487ca	1261	/* unacked queue is now empty */
idinor	0:dcf3c92487ca	1262	pcb->unacked = NULL;
idinor	0:dcf3c92487ca	1263
idinor	0:dcf3c92487ca	1264	/* increment number of retransmissions */
idinor	0:dcf3c92487ca	1265	++pcb->nrtx;
idinor	0:dcf3c92487ca	1266
idinor	0:dcf3c92487ca	1267	/* Don't take any RTT measurements after retransmitting. */
idinor	0:dcf3c92487ca	1268	pcb->rttest = 0;
idinor	0:dcf3c92487ca	1269
idinor	0:dcf3c92487ca	1270	/* Do the actual retransmission */
idinor	0:dcf3c92487ca	1271	tcp_output(pcb);
idinor	0:dcf3c92487ca	1272	}
idinor	0:dcf3c92487ca	1273
idinor	0:dcf3c92487ca	1274	/**
idinor	0:dcf3c92487ca	1275	* Requeue the first unacked segment for retransmission
idinor	0:dcf3c92487ca	1276	*
idinor	0:dcf3c92487ca	1277	* Called by tcp_receive() for fast retramsmit.
idinor	0:dcf3c92487ca	1278	*
idinor	0:dcf3c92487ca	1279	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
idinor	0:dcf3c92487ca	1280	*/
idinor	0:dcf3c92487ca	1281	void
idinor	0:dcf3c92487ca	1282	tcp_rexmit(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	1283	{
idinor	0:dcf3c92487ca	1284	struct tcp_seg *seg;
idinor	0:dcf3c92487ca	1285	struct tcp_seg **cur_seg;
idinor	0:dcf3c92487ca	1286
idinor	0:dcf3c92487ca	1287	if (pcb->unacked == NULL) {
idinor	0:dcf3c92487ca	1288	return;
idinor	0:dcf3c92487ca	1289	}
idinor	0:dcf3c92487ca	1290
idinor	0:dcf3c92487ca	1291	/* Move the first unacked segment to the unsent queue */
idinor	0:dcf3c92487ca	1292	/* Keep the unsent queue sorted. */
idinor	0:dcf3c92487ca	1293	seg = pcb->unacked;
idinor	0:dcf3c92487ca	1294	pcb->unacked = seg->next;
idinor	0:dcf3c92487ca	1295
idinor	0:dcf3c92487ca	1296	cur_seg = &(pcb->unsent);
idinor	0:dcf3c92487ca	1297	while (*cur_seg &&
idinor	0:dcf3c92487ca	1298	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
idinor	0:dcf3c92487ca	1299	cur_seg = &((*cur_seg)->next );
idinor	0:dcf3c92487ca	1300	}
idinor	0:dcf3c92487ca	1301	seg->next = *cur_seg;
idinor	0:dcf3c92487ca	1302	*cur_seg = seg;
idinor	0:dcf3c92487ca	1303
idinor	0:dcf3c92487ca	1304	++pcb->nrtx;
idinor	0:dcf3c92487ca	1305
idinor	0:dcf3c92487ca	1306	/* Don't take any rtt measurements after retransmitting. */
idinor	0:dcf3c92487ca	1307	pcb->rttest = 0;
idinor	0:dcf3c92487ca	1308
idinor	0:dcf3c92487ca	1309	/* Do the actual retransmission. */
idinor	0:dcf3c92487ca	1310	snmp_inc_tcpretranssegs();
idinor	0:dcf3c92487ca	1311	/* No need to call tcp_output: we are always called from tcp_input()
idinor	0:dcf3c92487ca	1312	and thus tcp_output directly returns. */
idinor	0:dcf3c92487ca	1313	}
idinor	0:dcf3c92487ca	1314
idinor	0:dcf3c92487ca	1315
idinor	0:dcf3c92487ca	1316	/**
idinor	0:dcf3c92487ca	1317	* Handle retransmission after three dupacks received
idinor	0:dcf3c92487ca	1318	*
idinor	0:dcf3c92487ca	1319	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
idinor	0:dcf3c92487ca	1320	*/
idinor	0:dcf3c92487ca	1321	void
idinor	0:dcf3c92487ca	1322	tcp_rexmit_fast(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	1323	{
idinor	0:dcf3c92487ca	1324	if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
idinor	0:dcf3c92487ca	1325	/* This is fast retransmit. Retransmit the first unacked segment. */
idinor	0:dcf3c92487ca	1326	LWIP_DEBUGF(TCP_FR_DEBUG,
idinor	0:dcf3c92487ca	1327	("tcp_receive: dupacks %"U16_F" (%"U32_F
idinor	0:dcf3c92487ca	1328	"), fast retransmit %"U32_F"\n",
idinor	0:dcf3c92487ca	1329	(u16_t)pcb->dupacks, pcb->lastack,
idinor	0:dcf3c92487ca	1330	ntohl(pcb->unacked->tcphdr->seqno)));
idinor	0:dcf3c92487ca	1331	tcp_rexmit(pcb);
idinor	0:dcf3c92487ca	1332
idinor	0:dcf3c92487ca	1333	/* Set ssthresh to half of the minimum of the current
idinor	0:dcf3c92487ca	1334	* cwnd and the advertised window */
idinor	0:dcf3c92487ca	1335	if (pcb->cwnd > pcb->snd_wnd) {
idinor	0:dcf3c92487ca	1336	pcb->ssthresh = pcb->snd_wnd / 2;
idinor	0:dcf3c92487ca	1337	} else {
idinor	0:dcf3c92487ca	1338	pcb->ssthresh = pcb->cwnd / 2;
idinor	0:dcf3c92487ca	1339	}
idinor	0:dcf3c92487ca	1340
idinor	0:dcf3c92487ca	1341	/* The minimum value for ssthresh should be 2 MSS */
idinor	0:dcf3c92487ca	1342	if (pcb->ssthresh < 2*pcb->mss) {
idinor	0:dcf3c92487ca	1343	LWIP_DEBUGF(TCP_FR_DEBUG,
idinor	0:dcf3c92487ca	1344	("tcp_receive: The minimum value for ssthresh %"U16_F
idinor	0:dcf3c92487ca	1345	" should be min 2 mss %"U16_F"...\n",
idinor	0:dcf3c92487ca	1346	pcb->ssthresh, 2*pcb->mss));
idinor	0:dcf3c92487ca	1347	pcb->ssthresh = 2*pcb->mss;
idinor	0:dcf3c92487ca	1348	}
idinor	0:dcf3c92487ca	1349
idinor	0:dcf3c92487ca	1350	pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
idinor	0:dcf3c92487ca	1351	pcb->flags \|= TF_INFR;
idinor	0:dcf3c92487ca	1352	}
idinor	0:dcf3c92487ca	1353	}
idinor	0:dcf3c92487ca	1354
idinor	0:dcf3c92487ca	1355
idinor	0:dcf3c92487ca	1356	/**
idinor	0:dcf3c92487ca	1357	* Send keepalive packets to keep a connection active although
idinor	0:dcf3c92487ca	1358	* no data is sent over it.
idinor	0:dcf3c92487ca	1359	*
idinor	0:dcf3c92487ca	1360	* Called by tcp_slowtmr()
idinor	0:dcf3c92487ca	1361	*
idinor	0:dcf3c92487ca	1362	* @param pcb the tcp_pcb for which to send a keepalive packet
idinor	0:dcf3c92487ca	1363	*/
idinor	0:dcf3c92487ca	1364	void
idinor	0:dcf3c92487ca	1365	tcp_keepalive(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	1366	{
idinor	0:dcf3c92487ca	1367	struct pbuf *p;
idinor	0:dcf3c92487ca	1368	struct tcp_hdr *tcphdr;
idinor	0:dcf3c92487ca	1369
idinor	0:dcf3c92487ca	1370	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
idinor	0:dcf3c92487ca	1371	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
idinor	0:dcf3c92487ca	1372	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
idinor	0:dcf3c92487ca	1373
idinor	0:dcf3c92487ca	1374	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
idinor	0:dcf3c92487ca	1375	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
idinor	0:dcf3c92487ca	1376
idinor	0:dcf3c92487ca	1377	p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
idinor	0:dcf3c92487ca	1378	if(p == NULL) {
idinor	0:dcf3c92487ca	1379	LWIP_DEBUGF(TCP_DEBUG,
idinor	0:dcf3c92487ca	1380	("tcp_keepalive: could not allocate memory for pbuf\n"));
idinor	0:dcf3c92487ca	1381	return;
idinor	0:dcf3c92487ca	1382	}
idinor	0:dcf3c92487ca	1383	tcphdr = (struct tcp_hdr *)p->payload;
idinor	0:dcf3c92487ca	1384
idinor	0:dcf3c92487ca	1385	#if CHECKSUM_GEN_TCP
idinor	0:dcf3c92487ca	1386	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
idinor	0:dcf3c92487ca	1387	IP_PROTO_TCP, p->tot_len);
idinor	0:dcf3c92487ca	1388	#endif
idinor	0:dcf3c92487ca	1389	TCP_STATS_INC(tcp.xmit);
idinor	0:dcf3c92487ca	1390
idinor	0:dcf3c92487ca	1391	/* Send output to IP */
idinor	0:dcf3c92487ca	1392	#if LWIP_NETIF_HWADDRHINT
idinor	0:dcf3c92487ca	1393	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
idinor	0:dcf3c92487ca	1394	&(pcb->addr_hint));
idinor	0:dcf3c92487ca	1395	#else /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	1396	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
idinor	0:dcf3c92487ca	1397	#endif /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	1398
idinor	0:dcf3c92487ca	1399	pbuf_free(p);
idinor	0:dcf3c92487ca	1400
idinor	0:dcf3c92487ca	1401	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
idinor	0:dcf3c92487ca	1402	pcb->snd_nxt - 1, pcb->rcv_nxt));
idinor	0:dcf3c92487ca	1403	}
idinor	0:dcf3c92487ca	1404
idinor	0:dcf3c92487ca	1405
idinor	0:dcf3c92487ca	1406	/**
idinor	0:dcf3c92487ca	1407	* Send persist timer zero-window probes to keep a connection active
idinor	0:dcf3c92487ca	1408	* when a window update is lost.
idinor	0:dcf3c92487ca	1409	*
idinor	0:dcf3c92487ca	1410	* Called by tcp_slowtmr()
idinor	0:dcf3c92487ca	1411	*
idinor	0:dcf3c92487ca	1412	* @param pcb the tcp_pcb for which to send a zero-window probe packet
idinor	0:dcf3c92487ca	1413	*/
idinor	0:dcf3c92487ca	1414	void
idinor	0:dcf3c92487ca	1415	tcp_zero_window_probe(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	1416	{
idinor	0:dcf3c92487ca	1417	struct pbuf *p;
idinor	0:dcf3c92487ca	1418	struct tcp_hdr *tcphdr;
idinor	0:dcf3c92487ca	1419	struct tcp_seg *seg;
idinor	0:dcf3c92487ca	1420	u16_t len;
idinor	0:dcf3c92487ca	1421	u8_t is_fin;
idinor	0:dcf3c92487ca	1422
idinor	0:dcf3c92487ca	1423	LWIP_DEBUGF(TCP_DEBUG,
idinor	0:dcf3c92487ca	1424	("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
idinor	0:dcf3c92487ca	1425	U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
idinor	0:dcf3c92487ca	1426	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
idinor	0:dcf3c92487ca	1427	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
idinor	0:dcf3c92487ca	1428
idinor	0:dcf3c92487ca	1429	LWIP_DEBUGF(TCP_DEBUG,
idinor	0:dcf3c92487ca	1430	("tcp_zero_window_probe: tcp_ticks %"U32_F
idinor	0:dcf3c92487ca	1431	" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
idinor	0:dcf3c92487ca	1432	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
idinor	0:dcf3c92487ca	1433
idinor	0:dcf3c92487ca	1434	seg = pcb->unacked;
idinor	0:dcf3c92487ca	1435
idinor	0:dcf3c92487ca	1436	if(seg == NULL) {
idinor	0:dcf3c92487ca	1437	seg = pcb->unsent;
idinor	0:dcf3c92487ca	1438	}
idinor	0:dcf3c92487ca	1439	if(seg == NULL) {
idinor	0:dcf3c92487ca	1440	return;
idinor	0:dcf3c92487ca	1441	}
idinor	0:dcf3c92487ca	1442
idinor	0:dcf3c92487ca	1443	is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
idinor	0:dcf3c92487ca	1444	/* we want to send one seqno: either FIN or data (no options) */
idinor	0:dcf3c92487ca	1445	len = is_fin ? 0 : 1;
idinor	0:dcf3c92487ca	1446
idinor	0:dcf3c92487ca	1447	p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
idinor	0:dcf3c92487ca	1448	if(p == NULL) {
idinor	0:dcf3c92487ca	1449	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
idinor	0:dcf3c92487ca	1450	return;
idinor	0:dcf3c92487ca	1451	}
idinor	0:dcf3c92487ca	1452	tcphdr = (struct tcp_hdr *)p->payload;
idinor	0:dcf3c92487ca	1453
idinor	0:dcf3c92487ca	1454	if (is_fin) {
idinor	0:dcf3c92487ca	1455	/* FIN segment, no data */
idinor	0:dcf3c92487ca	1456	TCPH_FLAGS_SET(tcphdr, TCP_ACK \| TCP_FIN);
idinor	0:dcf3c92487ca	1457	} else {
idinor	0:dcf3c92487ca	1458	/* Data segment, copy in one byte from the head of the unacked queue */
idinor	0:dcf3c92487ca	1459	((char )p->payload + TCP_HLEN) = (char )seg->dataptr;
idinor	0:dcf3c92487ca	1460	}
idinor	0:dcf3c92487ca	1461
idinor	0:dcf3c92487ca	1462	#if CHECKSUM_GEN_TCP
idinor	0:dcf3c92487ca	1463	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
idinor	0:dcf3c92487ca	1464	IP_PROTO_TCP, p->tot_len);
idinor	0:dcf3c92487ca	1465	#endif
idinor	0:dcf3c92487ca	1466	TCP_STATS_INC(tcp.xmit);
idinor	0:dcf3c92487ca	1467
idinor	0:dcf3c92487ca	1468	/* Send output to IP */
idinor	0:dcf3c92487ca	1469	#if LWIP_NETIF_HWADDRHINT
idinor	0:dcf3c92487ca	1470	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
idinor	0:dcf3c92487ca	1471	&(pcb->addr_hint));
idinor	0:dcf3c92487ca	1472	#else /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	1473	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
idinor	0:dcf3c92487ca	1474	#endif /* LWIP_NETIF_HWADDRHINT*/
idinor	0:dcf3c92487ca	1475
idinor	0:dcf3c92487ca	1476	pbuf_free(p);
idinor	0:dcf3c92487ca	1477
idinor	0:dcf3c92487ca	1478	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
idinor	0:dcf3c92487ca	1479	" ackno %"U32_F".\n",
idinor	0:dcf3c92487ca	1480	pcb->snd_nxt - 1, pcb->rcv_nxt));
idinor	0:dcf3c92487ca	1481	}
idinor	0:dcf3c92487ca	1482	#endif /* LWIP_TCP */

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Type:	Library
Created:	20 Jul 2011
Imports:	35
Forks:	0
Commits:	1
Dependents:	1
Dependencies:	0
Followers:	1

lwip/core/tcp_out.c@0:dcf3c92487ca, 2011-07-20 (annotated)

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