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lwip/core/tcp_out.c@0:281d6ff68967, 2010-11-19 (annotated)

Committer:: hexley
Date:: Fri Nov 19 01:54:45 2010 +0000
Revision:: 0:281d6ff68967

Who changed what in which revision?

User	Revision	Line number	New contents of line
hexley	0:281d6ff68967	1	/**
hexley	0:281d6ff68967	2	* @file
hexley	0:281d6ff68967	3	* Transmission Control Protocol, outgoing traffic
hexley	0:281d6ff68967	4	*
hexley	0:281d6ff68967	5	* The output functions of TCP.
hexley	0:281d6ff68967	6	*
hexley	0:281d6ff68967	7	*/
hexley	0:281d6ff68967	8
hexley	0:281d6ff68967	9	/*
hexley	0:281d6ff68967	10	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
hexley	0:281d6ff68967	11	* All rights reserved.
hexley	0:281d6ff68967	12	*
hexley	0:281d6ff68967	13	* Redistribution and use in source and binary forms, with or without modification,
hexley	0:281d6ff68967	14	* are permitted provided that the following conditions are met:
hexley	0:281d6ff68967	15	*
hexley	0:281d6ff68967	16	* 1. Redistributions of source code must retain the above copyright notice,
hexley	0:281d6ff68967	17	* this list of conditions and the following disclaimer.
hexley	0:281d6ff68967	18	* 2. Redistributions in binary form must reproduce the above copyright notice,
hexley	0:281d6ff68967	19	* this list of conditions and the following disclaimer in the documentation
hexley	0:281d6ff68967	20	* and/or other materials provided with the distribution.
hexley	0:281d6ff68967	21	* 3. The name of the author may not be used to endorse or promote products
hexley	0:281d6ff68967	22	* derived from this software without specific prior written permission.
hexley	0:281d6ff68967	23	*
hexley	0:281d6ff68967	24	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
hexley	0:281d6ff68967	25	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
hexley	0:281d6ff68967	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
hexley	0:281d6ff68967	27	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
hexley	0:281d6ff68967	28	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
hexley	0:281d6ff68967	29	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
hexley	0:281d6ff68967	30	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
hexley	0:281d6ff68967	31	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
hexley	0:281d6ff68967	32	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
hexley	0:281d6ff68967	33	* OF SUCH DAMAGE.
hexley	0:281d6ff68967	34	*
hexley	0:281d6ff68967	35	* This file is part of the lwIP TCP/IP stack.
hexley	0:281d6ff68967	36	*
hexley	0:281d6ff68967	37	* Author: Adam Dunkels <adam@sics.se>
hexley	0:281d6ff68967	38	*
hexley	0:281d6ff68967	39	*/
hexley	0:281d6ff68967	40
hexley	0:281d6ff68967	41	#include "lwip/opt.h"
hexley	0:281d6ff68967	42
hexley	0:281d6ff68967	43	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
hexley	0:281d6ff68967	44
hexley	0:281d6ff68967	45	#include "lwip/tcp_impl.h"
hexley	0:281d6ff68967	46	#include "lwip/def.h"
hexley	0:281d6ff68967	47	#include "lwip/mem.h"
hexley	0:281d6ff68967	48	#include "lwip/memp.h"
hexley	0:281d6ff68967	49	#include "lwip/sys.h"
hexley	0:281d6ff68967	50	#include "lwip/ip_addr.h"
hexley	0:281d6ff68967	51	#include "lwip/netif.h"
hexley	0:281d6ff68967	52	#include "lwip/inet_chksum.h"
hexley	0:281d6ff68967	53	#include "lwip/stats.h"
hexley	0:281d6ff68967	54	#include "lwip/snmp.h"
hexley	0:281d6ff68967	55
hexley	0:281d6ff68967	56	#include <string.h>
hexley	0:281d6ff68967	57
hexley	0:281d6ff68967	58	/* Define some copy-macros for checksum-on-copy so that the code looks
hexley	0:281d6ff68967	59	nicer by preventing too many ifdef's. */
hexley	0:281d6ff68967	60	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	61	#define TCP_DATA_COPY(dst, src, len, seg) do { \
hexley	0:281d6ff68967	62	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
hexley	0:281d6ff68967	63	len, &seg->chksum, &seg->chksum_swapped); \
hexley	0:281d6ff68967	64	seg->flags \|= TF_SEG_DATA_CHECKSUMMED; } while(0)
hexley	0:281d6ff68967	65	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
hexley	0:281d6ff68967	66	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
hexley	0:281d6ff68967	67	#else /* TCP_CHECKSUM_ON_COPY*/
hexley	0:281d6ff68967	68	#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
hexley	0:281d6ff68967	69	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
hexley	0:281d6ff68967	70	#endif /* TCP_CHECKSUM_ON_COPY*/
hexley	0:281d6ff68967	71
hexley	0:281d6ff68967	72	/** Define this to 1 for an extra check that the output checksum is valid
hexley	0:281d6ff68967	73	* (usefule when the checksum is generated by the application, not the stack) */
hexley	0:281d6ff68967	74	#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
hexley	0:281d6ff68967	75	#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
hexley	0:281d6ff68967	76	#endif
hexley	0:281d6ff68967	77
hexley	0:281d6ff68967	78	/* Forward declarations.*/
hexley	0:281d6ff68967	79	static void tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb);
hexley	0:281d6ff68967	80
hexley	0:281d6ff68967	81	/** Allocate a pbuf and create a tcphdr at p->payload, used for output
hexley	0:281d6ff68967	82	* functions other than the default tcp_output -> tcp_output_segment
hexley	0:281d6ff68967	83	* (e.g. tcp_send_empty_ack, etc.)
hexley	0:281d6ff68967	84	*
hexley	0:281d6ff68967	85	* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
hexley	0:281d6ff68967	86	* @param optlen length of header-options
hexley	0:281d6ff68967	87	* @param datalen length of tcp data to reserve in pbuf
hexley	0:281d6ff68967	88	* @param seqno_be seqno in network byte order (big-endian)
hexley	0:281d6ff68967	89	* @return pbuf with p->payload being the tcp_hdr
hexley	0:281d6ff68967	90	*/
hexley	0:281d6ff68967	91	static struct pbuf *
hexley	0:281d6ff68967	92	tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
hexley	0:281d6ff68967	93	u32_t seqno_be /* already in network byte order */)
hexley	0:281d6ff68967	94	{
hexley	0:281d6ff68967	95	struct tcp_hdr *tcphdr;
hexley	0:281d6ff68967	96	struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
hexley	0:281d6ff68967	97	if (p != NULL) {
hexley	0:281d6ff68967	98	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
hexley	0:281d6ff68967	99	(p->len >= TCP_HLEN + optlen));
hexley	0:281d6ff68967	100	tcphdr = (struct tcp_hdr *)p->payload;
hexley	0:281d6ff68967	101	tcphdr->src = htons(pcb->local_port);
hexley	0:281d6ff68967	102	tcphdr->dest = htons(pcb->remote_port);
hexley	0:281d6ff68967	103	tcphdr->seqno = seqno_be;
hexley	0:281d6ff68967	104	tcphdr->ackno = htonl(pcb->rcv_nxt);
hexley	0:281d6ff68967	105	TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
hexley	0:281d6ff68967	106	tcphdr->wnd = htons(pcb->rcv_ann_wnd);
hexley	0:281d6ff68967	107	tcphdr->chksum = 0;
hexley	0:281d6ff68967	108	tcphdr->urgp = 0;
hexley	0:281d6ff68967	109
hexley	0:281d6ff68967	110	/* If we're sending a packet, update the announced right window edge */
hexley	0:281d6ff68967	111	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
hexley	0:281d6ff68967	112	}
hexley	0:281d6ff68967	113	return p;
hexley	0:281d6ff68967	114	}
hexley	0:281d6ff68967	115
hexley	0:281d6ff68967	116	/**
hexley	0:281d6ff68967	117	* Called by tcp_close() to send a segment including FIN flag but not data.
hexley	0:281d6ff68967	118	*
hexley	0:281d6ff68967	119	* @param pcb the tcp_pcb over which to send a segment
hexley	0:281d6ff68967	120	* @return ERR_OK if sent, another err_t otherwise
hexley	0:281d6ff68967	121	*/
hexley	0:281d6ff68967	122	err_t
hexley	0:281d6ff68967	123	tcp_send_fin(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	124	{
hexley	0:281d6ff68967	125	/* first, try to add the fin to the last unsent segment */
hexley	0:281d6ff68967	126	if (pcb->unsent != NULL) {
hexley	0:281d6ff68967	127	struct tcp_seg *last_unsent;
hexley	0:281d6ff68967	128	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
hexley	0:281d6ff68967	129	last_unsent = last_unsent->next);
hexley	0:281d6ff68967	130
hexley	0:281d6ff68967	131	if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN \| TCP_FIN \| TCP_RST)) == 0) {
hexley	0:281d6ff68967	132	/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
hexley	0:281d6ff68967	133	TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
hexley	0:281d6ff68967	134	return ERR_OK;
hexley	0:281d6ff68967	135	}
hexley	0:281d6ff68967	136	}
hexley	0:281d6ff68967	137	/* no data, no length, flags, copy=1, no optdata */
hexley	0:281d6ff68967	138	return tcp_enqueue_flags(pcb, TCP_FIN);
hexley	0:281d6ff68967	139	}
hexley	0:281d6ff68967	140
hexley	0:281d6ff68967	141	/**
hexley	0:281d6ff68967	142	* Create a TCP segment with prefilled header.
hexley	0:281d6ff68967	143	*
hexley	0:281d6ff68967	144	* Called by tcp_write and tcp_enqueue_flags.
hexley	0:281d6ff68967	145	*
hexley	0:281d6ff68967	146	* @param pcb Protocol control block for the TCP connection.
hexley	0:281d6ff68967	147	* @param p pbuf that is used to hold the TCP header.
hexley	0:281d6ff68967	148	* @param flags TCP flags for header.
hexley	0:281d6ff68967	149	* @param seqno TCP sequence number of this packet
hexley	0:281d6ff68967	150	* @param optflags options to include in TCP header
hexley	0:281d6ff68967	151	* @return a new tcp_seg pointing to p, or NULL.
hexley	0:281d6ff68967	152	* The TCP header is filled in except ackno and wnd.
hexley	0:281d6ff68967	153	* p is freed on failure.
hexley	0:281d6ff68967	154	*/
hexley	0:281d6ff68967	155	static struct tcp_seg *
hexley	0:281d6ff68967	156	tcp_create_segment(struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
hexley	0:281d6ff68967	157	{
hexley	0:281d6ff68967	158	struct tcp_seg *seg;
hexley	0:281d6ff68967	159	u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
hexley	0:281d6ff68967	160
hexley	0:281d6ff68967	161	if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
hexley	0:281d6ff68967	162	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no memory.\n"));
hexley	0:281d6ff68967	163	pbuf_free(p);
hexley	0:281d6ff68967	164	return NULL;
hexley	0:281d6ff68967	165	}
hexley	0:281d6ff68967	166	seg->flags = optflags;
hexley	0:281d6ff68967	167	seg->next = NULL;
hexley	0:281d6ff68967	168	seg->p = p;
hexley	0:281d6ff68967	169	seg->dataptr = p->payload;
hexley	0:281d6ff68967	170	seg->len = p->tot_len - optlen;
hexley	0:281d6ff68967	171	#if TCP_OVERSIZE_DBGCHECK
hexley	0:281d6ff68967	172	seg->oversize_left = 0;
hexley	0:281d6ff68967	173	#endif /* TCP_OVERSIZE_DBGCHECK */
hexley	0:281d6ff68967	174	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	175	seg->chksum = 0;
hexley	0:281d6ff68967	176	seg->chksum_swapped = 0;
hexley	0:281d6ff68967	177	/* check optflags */
hexley	0:281d6ff68967	178	LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
hexley	0:281d6ff68967	179	(optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
hexley	0:281d6ff68967	180	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	181
hexley	0:281d6ff68967	182	/* build TCP header */
hexley	0:281d6ff68967	183	if (pbuf_header(p, TCP_HLEN)) {
hexley	0:281d6ff68967	184	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
hexley	0:281d6ff68967	185	TCP_STATS_INC(tcp.err);
hexley	0:281d6ff68967	186	tcp_seg_free(seg);
hexley	0:281d6ff68967	187	return NULL;
hexley	0:281d6ff68967	188	}
hexley	0:281d6ff68967	189	seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
hexley	0:281d6ff68967	190	seg->tcphdr->src = htons(pcb->local_port);
hexley	0:281d6ff68967	191	seg->tcphdr->dest = htons(pcb->remote_port);
hexley	0:281d6ff68967	192	seg->tcphdr->seqno = htonl(seqno);
hexley	0:281d6ff68967	193	/* ackno is set in tcp_output */
hexley	0:281d6ff68967	194	TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
hexley	0:281d6ff68967	195	/* wnd and chksum are set in tcp_output */
hexley	0:281d6ff68967	196	seg->tcphdr->urgp = 0;
hexley	0:281d6ff68967	197	return seg;
hexley	0:281d6ff68967	198	}
hexley	0:281d6ff68967	199
hexley	0:281d6ff68967	200	/**
hexley	0:281d6ff68967	201	* Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
hexley	0:281d6ff68967	202	*
hexley	0:281d6ff68967	203	* This function is like pbuf_alloc(layer, length, PBUF_RAM) except
hexley	0:281d6ff68967	204	* there may be extra bytes available at the end.
hexley	0:281d6ff68967	205	*
hexley	0:281d6ff68967	206	* @param layer flag to define header size.
hexley	0:281d6ff68967	207	* @param length size of the pbuf's payload.
hexley	0:281d6ff68967	208	* @param max_length maximum usable size of payload+oversize.
hexley	0:281d6ff68967	209	* @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
hexley	0:281d6ff68967	210	* @param pcb The TCP connection that willo enqueue the pbuf.
hexley	0:281d6ff68967	211	* @param apiflags API flags given to tcp_write.
hexley	0:281d6ff68967	212	* @param first_seg true when this pbuf will be used in the first enqueued segment.
hexley	0:281d6ff68967	213	* @param
hexley	0:281d6ff68967	214	*/
hexley	0:281d6ff68967	215	#if TCP_OVERSIZE
hexley	0:281d6ff68967	216	static struct pbuf *
hexley	0:281d6ff68967	217	tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
hexley	0:281d6ff68967	218	u16_t oversize, struct tcp_pcb pcb, u8_t apiflags,
hexley	0:281d6ff68967	219	u8_t first_seg)
hexley	0:281d6ff68967	220	{
hexley	0:281d6ff68967	221	struct pbuf *p;
hexley	0:281d6ff68967	222	u16_t alloc = length;
hexley	0:281d6ff68967	223
hexley	0:281d6ff68967	224	#if LWIP_NETIF_TX_SINGLE_PBUF
hexley	0:281d6ff68967	225	LWIP_UNUSED_ARG(max_length);
hexley	0:281d6ff68967	226	LWIP_UNUSED_ARG(pcb);
hexley	0:281d6ff68967	227	LWIP_UNUSED_ARG(apiflags);
hexley	0:281d6ff68967	228	LWIP_UNUSED_ARG(first_seg);
hexley	0:281d6ff68967	229	/* always create MSS-sized pbufs */
hexley	0:281d6ff68967	230	alloc = TCP_MSS;
hexley	0:281d6ff68967	231	#else /* LWIP_NETIF_TX_SINGLE_PBUF */
hexley	0:281d6ff68967	232	if (length < max_length) {
hexley	0:281d6ff68967	233	/* Should we allocate an oversized pbuf, or just the minimum
hexley	0:281d6ff68967	234	* length required? If tcp_write is going to be called again
hexley	0:281d6ff68967	235	* before this segment is transmitted, we want the oversized
hexley	0:281d6ff68967	236	* buffer. If the segment will be transmitted immediately, we can
hexley	0:281d6ff68967	237	* save memory by allocating only length. We use a simple
hexley	0:281d6ff68967	238	* heuristic based on the following information:
hexley	0:281d6ff68967	239	*
hexley	0:281d6ff68967	240	* Did the user set TCP_WRITE_FLAG_MORE?
hexley	0:281d6ff68967	241	*
hexley	0:281d6ff68967	242	* Will the Nagle algorithm defer transmission of this segment?
hexley	0:281d6ff68967	243	*/
hexley	0:281d6ff68967	244	if ((apiflags & TCP_WRITE_FLAG_MORE) \|\|
hexley	0:281d6ff68967	245	(!(pcb->flags & TF_NODELAY) &&
hexley	0:281d6ff68967	246	(!first_seg \|\|
hexley	0:281d6ff68967	247	pcb->unsent != NULL \|\|
hexley	0:281d6ff68967	248	pcb->unacked != NULL))) {
hexley	0:281d6ff68967	249	alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
hexley	0:281d6ff68967	250	}
hexley	0:281d6ff68967	251	}
hexley	0:281d6ff68967	252	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
hexley	0:281d6ff68967	253	p = pbuf_alloc(layer, alloc, PBUF_RAM);
hexley	0:281d6ff68967	254	if (p == NULL) {
hexley	0:281d6ff68967	255	return NULL;
hexley	0:281d6ff68967	256	}
hexley	0:281d6ff68967	257	LWIP_ASSERT("need unchained pbuf", p->next == NULL);
hexley	0:281d6ff68967	258	*oversize = p->len - length;
hexley	0:281d6ff68967	259	/* trim p->len to the currently used size */
hexley	0:281d6ff68967	260	p->len = p->tot_len = length;
hexley	0:281d6ff68967	261	return p;
hexley	0:281d6ff68967	262	}
hexley	0:281d6ff68967	263	#else /* TCP_OVERSIZE */
hexley	0:281d6ff68967	264	#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
hexley	0:281d6ff68967	265	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	266
hexley	0:281d6ff68967	267	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	268	/** Add a checksum of newly added data to the segment */
hexley	0:281d6ff68967	269	static void
hexley	0:281d6ff68967	270	tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
hexley	0:281d6ff68967	271	u8_t *seg_chksum_swapped)
hexley	0:281d6ff68967	272	{
hexley	0:281d6ff68967	273	u32_t helper;
hexley	0:281d6ff68967	274	/* add chksum to old chksum and fold to u16_t */
hexley	0:281d6ff68967	275	helper = chksum + *seg_chksum;
hexley	0:281d6ff68967	276	chksum = FOLD_U32T(helper);
hexley	0:281d6ff68967	277	if ((len & 1) != 0) {
hexley	0:281d6ff68967	278	seg_chksum_swapped = 1 - seg_chksum_swapped;
hexley	0:281d6ff68967	279	chksum = SWAP_BYTES_IN_WORD(chksum);
hexley	0:281d6ff68967	280	}
hexley	0:281d6ff68967	281	*seg_chksum = chksum;
hexley	0:281d6ff68967	282	}
hexley	0:281d6ff68967	283	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	284
hexley	0:281d6ff68967	285	/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
hexley	0:281d6ff68967	286	*
hexley	0:281d6ff68967	287	* @param pcb the tcp pcb to check for
hexley	0:281d6ff68967	288	* @param len length of data to send (checked agains snd_buf)
hexley	0:281d6ff68967	289	* @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
hexley	0:281d6ff68967	290	*/
hexley	0:281d6ff68967	291	static err_t
hexley	0:281d6ff68967	292	tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
hexley	0:281d6ff68967	293	{
hexley	0:281d6ff68967	294	/* connection is in invalid state for data transmission? */
hexley	0:281d6ff68967	295	if ((pcb->state != ESTABLISHED) &&
hexley	0:281d6ff68967	296	(pcb->state != CLOSE_WAIT) &&
hexley	0:281d6ff68967	297	(pcb->state != SYN_SENT) &&
hexley	0:281d6ff68967	298	(pcb->state != SYN_RCVD)) {
hexley	0:281d6ff68967	299	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_STATE \| LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
hexley	0:281d6ff68967	300	return ERR_CONN;
hexley	0:281d6ff68967	301	} else if (len == 0) {
hexley	0:281d6ff68967	302	return ERR_OK;
hexley	0:281d6ff68967	303	}
hexley	0:281d6ff68967	304
hexley	0:281d6ff68967	305	/* fail on too much data */
hexley	0:281d6ff68967	306	if (len > pcb->snd_buf) {
hexley	0:281d6ff68967	307	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
hexley	0:281d6ff68967	308	len, pcb->snd_buf));
hexley	0:281d6ff68967	309	pcb->flags \|= TF_NAGLEMEMERR;
hexley	0:281d6ff68967	310	return ERR_MEM;
hexley	0:281d6ff68967	311	}
hexley	0:281d6ff68967	312
hexley	0:281d6ff68967	313	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
hexley	0:281d6ff68967	314
hexley	0:281d6ff68967	315	/* If total number of pbufs on the unsent/unacked queues exceeds the
hexley	0:281d6ff68967	316	* configured maximum, return an error */
hexley	0:281d6ff68967	317	/* check for configured max queuelen and possible overflow */
hexley	0:281d6ff68967	318	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
hexley	0:281d6ff68967	319	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
hexley	0:281d6ff68967	320	pcb->snd_queuelen, TCP_SND_QUEUELEN));
hexley	0:281d6ff68967	321	TCP_STATS_INC(tcp.memerr);
hexley	0:281d6ff68967	322	pcb->flags \|= TF_NAGLEMEMERR;
hexley	0:281d6ff68967	323	return ERR_MEM;
hexley	0:281d6ff68967	324	}
hexley	0:281d6ff68967	325	if (pcb->snd_queuelen != 0) {
hexley	0:281d6ff68967	326	LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
hexley	0:281d6ff68967	327	pcb->unacked != NULL \|\| pcb->unsent != NULL);
hexley	0:281d6ff68967	328	} else {
hexley	0:281d6ff68967	329	LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
hexley	0:281d6ff68967	330	pcb->unacked == NULL && pcb->unsent == NULL);
hexley	0:281d6ff68967	331	}
hexley	0:281d6ff68967	332	return ERR_OK;
hexley	0:281d6ff68967	333	}
hexley	0:281d6ff68967	334
hexley	0:281d6ff68967	335	/**
hexley	0:281d6ff68967	336	* Write data for sending (but does not send it immediately).
hexley	0:281d6ff68967	337	*
hexley	0:281d6ff68967	338	* It waits in the expectation of more data being sent soon (as
hexley	0:281d6ff68967	339	* it can send them more efficiently by combining them together).
hexley	0:281d6ff68967	340	* To prompt the system to send data now, call tcp_output() after
hexley	0:281d6ff68967	341	* calling tcp_write().
hexley	0:281d6ff68967	342	*
hexley	0:281d6ff68967	343	* @param pcb Protocol control block for the TCP connection to enqueue data for.
hexley	0:281d6ff68967	344	* @param arg Pointer to the data to be enqueued for sending.
hexley	0:281d6ff68967	345	* @param len Data length in bytes
hexley	0:281d6ff68967	346	* @param apiflags combination of following flags :
hexley	0:281d6ff68967	347	* - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
hexley	0:281d6ff68967	348	* - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
hexley	0:281d6ff68967	349	* @return ERR_OK if enqueued, another err_t on error
hexley	0:281d6ff68967	350	*/
hexley	0:281d6ff68967	351	err_t
hexley	0:281d6ff68967	352	tcp_write(struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
hexley	0:281d6ff68967	353	{
hexley	0:281d6ff68967	354	struct pbuf *concat_p = NULL;
hexley	0:281d6ff68967	355	struct tcp_seg last_unsent = NULL, seg = NULL, prev_seg = NULL, queue = NULL;
hexley	0:281d6ff68967	356	u16_t pos = 0; /* position in 'arg' data */
hexley	0:281d6ff68967	357	u16_t queuelen;
hexley	0:281d6ff68967	358	u8_t optlen = 0;
hexley	0:281d6ff68967	359	u8_t optflags = 0;
hexley	0:281d6ff68967	360	#if TCP_OVERSIZE
hexley	0:281d6ff68967	361	u16_t oversize = 0;
hexley	0:281d6ff68967	362	u16_t oversize_used = 0;
hexley	0:281d6ff68967	363	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	364	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	365	u16_t concat_chksum = 0;
hexley	0:281d6ff68967	366	u8_t concat_chksum_swapped = 0;
hexley	0:281d6ff68967	367	u16_t concat_chksummed = 0;
hexley	0:281d6ff68967	368	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	369	err_t err;
hexley	0:281d6ff68967	370
hexley	0:281d6ff68967	371	#if LWIP_NETIF_TX_SINGLE_PBUF
hexley	0:281d6ff68967	372	/* Always copy to try to create single pbufs for TX */
hexley	0:281d6ff68967	373	apiflags \|= TCP_WRITE_FLAG_COPY;
hexley	0:281d6ff68967	374	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
hexley	0:281d6ff68967	375
hexley	0:281d6ff68967	376	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
hexley	0:281d6ff68967	377	(void *)pcb, arg, len, (u16_t)apiflags));
hexley	0:281d6ff68967	378	LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
hexley	0:281d6ff68967	379	arg != NULL, return ERR_ARG;);
hexley	0:281d6ff68967	380
hexley	0:281d6ff68967	381	err = tcp_write_checks(pcb, len);
hexley	0:281d6ff68967	382	if (err != ERR_OK) {
hexley	0:281d6ff68967	383	return err;
hexley	0:281d6ff68967	384	}
hexley	0:281d6ff68967	385	queuelen = pcb->snd_queuelen;
hexley	0:281d6ff68967	386
hexley	0:281d6ff68967	387	#if LWIP_TCP_TIMESTAMPS
hexley	0:281d6ff68967	388	if ((pcb->flags & TF_TIMESTAMP)) {
hexley	0:281d6ff68967	389	optflags = TF_SEG_OPTS_TS;
hexley	0:281d6ff68967	390	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
hexley	0:281d6ff68967	391	}
hexley	0:281d6ff68967	392	#endif /* LWIP_TCP_TIMESTAMPS */
hexley	0:281d6ff68967	393
hexley	0:281d6ff68967	394
hexley	0:281d6ff68967	395	/*
hexley	0:281d6ff68967	396	* TCP segmentation is done in three phases with increasing complexity:
hexley	0:281d6ff68967	397	*
hexley	0:281d6ff68967	398	* 1. Copy data directly into an oversized pbuf.
hexley	0:281d6ff68967	399	* 2. Chain a new pbuf to the end of pcb->unsent.
hexley	0:281d6ff68967	400	* 3. Create new segments.
hexley	0:281d6ff68967	401	*
hexley	0:281d6ff68967	402	* We may run out of memory at any point. In that case we must
hexley	0:281d6ff68967	403	* return ERR_MEM and not change anything in pcb. Therefore, all
hexley	0:281d6ff68967	404	* changes are recorded in local variables and committed at the end
hexley	0:281d6ff68967	405	* of the function. Some pcb fields are maintained in local copies:
hexley	0:281d6ff68967	406	*
hexley	0:281d6ff68967	407	* queuelen = pcb->snd_queuelen
hexley	0:281d6ff68967	408	* oversize = pcb->unsent_oversize
hexley	0:281d6ff68967	409	*
hexley	0:281d6ff68967	410	* These variables are set consistently by the phases:
hexley	0:281d6ff68967	411	*
hexley	0:281d6ff68967	412	* seg points to the last segment tampered with.
hexley	0:281d6ff68967	413	*
hexley	0:281d6ff68967	414	* pos records progress as data is segmented.
hexley	0:281d6ff68967	415	*/
hexley	0:281d6ff68967	416
hexley	0:281d6ff68967	417	/* Find the tail of the unsent queue. */
hexley	0:281d6ff68967	418	if (pcb->unsent != NULL) {
hexley	0:281d6ff68967	419	u16_t space;
hexley	0:281d6ff68967	420	u16_t unsent_optlen;
hexley	0:281d6ff68967	421
hexley	0:281d6ff68967	422	/* @todo: this could be sped up by keeping last_unsent in the pcb */
hexley	0:281d6ff68967	423	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
hexley	0:281d6ff68967	424	last_unsent = last_unsent->next);
hexley	0:281d6ff68967	425
hexley	0:281d6ff68967	426	/* Usable space at the end of the last unsent segment */
hexley	0:281d6ff68967	427	unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
hexley	0:281d6ff68967	428	space = pcb->mss - (last_unsent->len + unsent_optlen);
hexley	0:281d6ff68967	429
hexley	0:281d6ff68967	430	/*
hexley	0:281d6ff68967	431	* Phase 1: Copy data directly into an oversized pbuf.
hexley	0:281d6ff68967	432	*
hexley	0:281d6ff68967	433	* The number of bytes copied is recorded in the oversize_used
hexley	0:281d6ff68967	434	* variable. The actual copying is done at the bottom of the
hexley	0:281d6ff68967	435	* function.
hexley	0:281d6ff68967	436	*/
hexley	0:281d6ff68967	437	#if TCP_OVERSIZE
hexley	0:281d6ff68967	438	#if TCP_OVERSIZE_DBGCHECK
hexley	0:281d6ff68967	439	/* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
hexley	0:281d6ff68967	440	LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
hexley	0:281d6ff68967	441	pcb->unsent_oversize == last_unsent->oversize_left);
hexley	0:281d6ff68967	442	#endif /* TCP_OVERSIZE_DBGCHECK */
hexley	0:281d6ff68967	443	oversize = pcb->unsent_oversize;
hexley	0:281d6ff68967	444	if (oversize > 0) {
hexley	0:281d6ff68967	445	LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
hexley	0:281d6ff68967	446	seg = last_unsent;
hexley	0:281d6ff68967	447	oversize_used = oversize < len ? oversize : len;
hexley	0:281d6ff68967	448	pos += oversize_used;
hexley	0:281d6ff68967	449	oversize -= oversize_used;
hexley	0:281d6ff68967	450	space -= oversize_used;
hexley	0:281d6ff68967	451	}
hexley	0:281d6ff68967	452	/* now we are either finished or oversize is zero */
hexley	0:281d6ff68967	453	LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) \|\| (pos == len));
hexley	0:281d6ff68967	454	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	455
hexley	0:281d6ff68967	456	/*
hexley	0:281d6ff68967	457	* Phase 2: Chain a new pbuf to the end of pcb->unsent.
hexley	0:281d6ff68967	458	*
hexley	0:281d6ff68967	459	* We don't extend segments containing SYN/FIN flags or options
hexley	0:281d6ff68967	460	* (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
hexley	0:281d6ff68967	461	* the end.
hexley	0:281d6ff68967	462	*/
hexley	0:281d6ff68967	463	if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
hexley	0:281d6ff68967	464	u16_t seglen = space < len - pos ? space : len - pos;
hexley	0:281d6ff68967	465	seg = last_unsent;
hexley	0:281d6ff68967	466
hexley	0:281d6ff68967	467	/* Create a pbuf with a copy or reference to seglen bytes. We
hexley	0:281d6ff68967	468	* can use PBUF_RAW here since the data appears in the middle of
hexley	0:281d6ff68967	469	* a segment. A header will never be prepended. */
hexley	0:281d6ff68967	470	if (apiflags & TCP_WRITE_FLAG_COPY) {
hexley	0:281d6ff68967	471	/* Data is copied */
hexley	0:281d6ff68967	472	if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
hexley	0:281d6ff68967	473	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
hexley	0:281d6ff68967	474	("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
hexley	0:281d6ff68967	475	seglen));
hexley	0:281d6ff68967	476	goto memerr;
hexley	0:281d6ff68967	477	}
hexley	0:281d6ff68967	478	#if TCP_OVERSIZE_DBGCHECK
hexley	0:281d6ff68967	479	last_unsent->oversize_left = oversize;
hexley	0:281d6ff68967	480	#endif /* TCP_OVERSIZE_DBGCHECK */
hexley	0:281d6ff68967	481	TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
hexley	0:281d6ff68967	482	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	483	concat_chksummed += seglen;
hexley	0:281d6ff68967	484	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	485	} else {
hexley	0:281d6ff68967	486	/* Data is not copied */
hexley	0:281d6ff68967	487	if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
hexley	0:281d6ff68967	488	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
hexley	0:281d6ff68967	489	("tcp_write: could not allocate memory for zero-copy pbuf\n"));
hexley	0:281d6ff68967	490	goto memerr;
hexley	0:281d6ff68967	491	}
hexley	0:281d6ff68967	492	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	493	/* calculate the checksum of nocopy-data */
hexley	0:281d6ff68967	494	tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
hexley	0:281d6ff68967	495	&concat_chksum, &concat_chksum_swapped);
hexley	0:281d6ff68967	496	concat_chksummed += seglen;
hexley	0:281d6ff68967	497	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	498	/* reference the non-volatile payload data */
hexley	0:281d6ff68967	499	concat_p->payload = (u8_t*)arg + pos;
hexley	0:281d6ff68967	500	}
hexley	0:281d6ff68967	501
hexley	0:281d6ff68967	502	pos += seglen;
hexley	0:281d6ff68967	503	queuelen += pbuf_clen(concat_p);
hexley	0:281d6ff68967	504	}
hexley	0:281d6ff68967	505	} else {
hexley	0:281d6ff68967	506	#if TCP_OVERSIZE
hexley	0:281d6ff68967	507	LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
hexley	0:281d6ff68967	508	pcb->unsent_oversize == 0);
hexley	0:281d6ff68967	509	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	510	}
hexley	0:281d6ff68967	511
hexley	0:281d6ff68967	512	/*
hexley	0:281d6ff68967	513	* Phase 3: Create new segments.
hexley	0:281d6ff68967	514	*
hexley	0:281d6ff68967	515	* The new segments are chained together in the local 'queue'
hexley	0:281d6ff68967	516	* variable, ready to be appended to pcb->unsent.
hexley	0:281d6ff68967	517	*/
hexley	0:281d6ff68967	518	while (pos < len) {
hexley	0:281d6ff68967	519	struct pbuf *p;
hexley	0:281d6ff68967	520	u16_t left = len - pos;
hexley	0:281d6ff68967	521	u16_t max_len = pcb->mss - optlen;
hexley	0:281d6ff68967	522	u16_t seglen = left > max_len ? max_len : left;
hexley	0:281d6ff68967	523	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	524	u16_t chksum = 0;
hexley	0:281d6ff68967	525	u8_t chksum_swapped = 0;
hexley	0:281d6ff68967	526	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	527
hexley	0:281d6ff68967	528	if (apiflags & TCP_WRITE_FLAG_COPY) {
hexley	0:281d6ff68967	529	/* If copy is set, memory should be allocated and data copied
hexley	0:281d6ff68967	530	* into pbuf */
hexley	0:281d6ff68967	531	if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, pcb->mss, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
hexley	0:281d6ff68967	532	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
hexley	0:281d6ff68967	533	goto memerr;
hexley	0:281d6ff68967	534	}
hexley	0:281d6ff68967	535	LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
hexley	0:281d6ff68967	536	(p->len >= seglen));
hexley	0:281d6ff68967	537	TCP_DATA_COPY2((char )p->payload + optlen, (u8_t)arg + pos, seglen, &chksum, &chksum_swapped);
hexley	0:281d6ff68967	538	} else {
hexley	0:281d6ff68967	539	/* Copy is not set: First allocate a pbuf for holding the data.
hexley	0:281d6ff68967	540	* Since the referenced data is available at least until it is
hexley	0:281d6ff68967	541	* sent out on the link (as it has to be ACKed by the remote
hexley	0:281d6ff68967	542	* party) we can safely use PBUF_ROM instead of PBUF_REF here.
hexley	0:281d6ff68967	543	*/
hexley	0:281d6ff68967	544	struct pbuf *p2;
hexley	0:281d6ff68967	545	#if TCP_OVERSIZE
hexley	0:281d6ff68967	546	LWIP_ASSERT("oversize == 0", oversize == 0);
hexley	0:281d6ff68967	547	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	548	if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
hexley	0:281d6ff68967	549	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
hexley	0:281d6ff68967	550	goto memerr;
hexley	0:281d6ff68967	551	}
hexley	0:281d6ff68967	552	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	553	/* calculate the checksum of nocopy-data */
hexley	0:281d6ff68967	554	chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
hexley	0:281d6ff68967	555	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	556	/* reference the non-volatile payload data */
hexley	0:281d6ff68967	557	p2->payload = (u8_t*)arg + pos;
hexley	0:281d6ff68967	558
hexley	0:281d6ff68967	559	/* Second, allocate a pbuf for the headers. */
hexley	0:281d6ff68967	560	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
hexley	0:281d6ff68967	561	/* If allocation fails, we have to deallocate the data pbuf as
hexley	0:281d6ff68967	562	* well. */
hexley	0:281d6ff68967	563	pbuf_free(p2);
hexley	0:281d6ff68967	564	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for header pbuf\n"));
hexley	0:281d6ff68967	565	goto memerr;
hexley	0:281d6ff68967	566	}
hexley	0:281d6ff68967	567	/* Concatenate the headers and data pbufs together. */
hexley	0:281d6ff68967	568	pbuf_cat(p/header/, p2/data/);
hexley	0:281d6ff68967	569	}
hexley	0:281d6ff68967	570
hexley	0:281d6ff68967	571	queuelen += pbuf_clen(p);
hexley	0:281d6ff68967	572
hexley	0:281d6ff68967	573	/* Now that there are more segments queued, we check again if the
hexley	0:281d6ff68967	574	* length of the queue exceeds the configured maximum or
hexley	0:281d6ff68967	575	* overflows. */
hexley	0:281d6ff68967	576	if ((queuelen > TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
hexley	0:281d6ff68967	577	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
hexley	0:281d6ff68967	578	pbuf_free(p);
hexley	0:281d6ff68967	579	goto memerr;
hexley	0:281d6ff68967	580	}
hexley	0:281d6ff68967	581
hexley	0:281d6ff68967	582	if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
hexley	0:281d6ff68967	583	goto memerr;
hexley	0:281d6ff68967	584	}
hexley	0:281d6ff68967	585	#if TCP_OVERSIZE_DBGCHECK
hexley	0:281d6ff68967	586	seg->oversize_left = oversize;
hexley	0:281d6ff68967	587	#endif /* TCP_OVERSIZE_DBGCHECK */
hexley	0:281d6ff68967	588	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	589	seg->chksum = chksum;
hexley	0:281d6ff68967	590	seg->chksum_swapped = chksum_swapped;
hexley	0:281d6ff68967	591	seg->flags \|= TF_SEG_DATA_CHECKSUMMED;
hexley	0:281d6ff68967	592	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	593	/* Fix dataptr for the nocopy case */
hexley	0:281d6ff68967	594	if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
hexley	0:281d6ff68967	595	seg->dataptr = (u8_t*)arg + pos;
hexley	0:281d6ff68967	596	}
hexley	0:281d6ff68967	597
hexley	0:281d6ff68967	598	/* first segment of to-be-queued data? */
hexley	0:281d6ff68967	599	if (queue == NULL) {
hexley	0:281d6ff68967	600	queue = seg;
hexley	0:281d6ff68967	601	} else {
hexley	0:281d6ff68967	602	/* Attach the segment to the end of the queued segments */
hexley	0:281d6ff68967	603	LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
hexley	0:281d6ff68967	604	prev_seg->next = seg;
hexley	0:281d6ff68967	605	}
hexley	0:281d6ff68967	606	/* remember last segment of to-be-queued data for next iteration */
hexley	0:281d6ff68967	607	prev_seg = seg;
hexley	0:281d6ff68967	608
hexley	0:281d6ff68967	609	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
hexley	0:281d6ff68967	610	ntohl(seg->tcphdr->seqno),
hexley	0:281d6ff68967	611	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
hexley	0:281d6ff68967	612
hexley	0:281d6ff68967	613	pos += seglen;
hexley	0:281d6ff68967	614	}
hexley	0:281d6ff68967	615
hexley	0:281d6ff68967	616	/*
hexley	0:281d6ff68967	617	* All three segmentation phases were successful. We can commit the
hexley	0:281d6ff68967	618	* transaction.
hexley	0:281d6ff68967	619	*/
hexley	0:281d6ff68967	620
hexley	0:281d6ff68967	621	/*
hexley	0:281d6ff68967	622	* Phase 1: If data has been added to the preallocated tail of
hexley	0:281d6ff68967	623	* last_unsent, we update the length fields of the pbuf chain.
hexley	0:281d6ff68967	624	*/
hexley	0:281d6ff68967	625	#if TCP_OVERSIZE
hexley	0:281d6ff68967	626	if (oversize_used > 0) {
hexley	0:281d6ff68967	627	struct pbuf *p;
hexley	0:281d6ff68967	628	/* Bump tot_len of whole chain, len of tail */
hexley	0:281d6ff68967	629	for (p = last_unsent->p; p; p = p->next) {
hexley	0:281d6ff68967	630	p->tot_len += oversize_used;
hexley	0:281d6ff68967	631	if (p->next == NULL) {
hexley	0:281d6ff68967	632	TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
hexley	0:281d6ff68967	633	p->len += oversize_used;
hexley	0:281d6ff68967	634	}
hexley	0:281d6ff68967	635	}
hexley	0:281d6ff68967	636	last_unsent->len += oversize_used;
hexley	0:281d6ff68967	637	#if TCP_OVERSIZE_DBGCHECK
hexley	0:281d6ff68967	638	last_unsent->oversize_left -= oversize_used;
hexley	0:281d6ff68967	639	#endif /* TCP_OVERSIZE_DBGCHECK */
hexley	0:281d6ff68967	640	}
hexley	0:281d6ff68967	641	pcb->unsent_oversize = oversize;
hexley	0:281d6ff68967	642	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	643
hexley	0:281d6ff68967	644	/*
hexley	0:281d6ff68967	645	* Phase 2: concat_p can be concatenated onto last_unsent->p
hexley	0:281d6ff68967	646	*/
hexley	0:281d6ff68967	647	if (concat_p != NULL) {
hexley	0:281d6ff68967	648	LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
hexley	0:281d6ff68967	649	(last_unsent != NULL));
hexley	0:281d6ff68967	650	pbuf_cat(last_unsent->p, concat_p);
hexley	0:281d6ff68967	651	last_unsent->len += concat_p->tot_len;
hexley	0:281d6ff68967	652	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	653	if (concat_chksummed) {
hexley	0:281d6ff68967	654	tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
hexley	0:281d6ff68967	655	&last_unsent->chksum_swapped);
hexley	0:281d6ff68967	656	last_unsent->flags \|= TF_SEG_DATA_CHECKSUMMED;
hexley	0:281d6ff68967	657	}
hexley	0:281d6ff68967	658	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	659	}
hexley	0:281d6ff68967	660
hexley	0:281d6ff68967	661	/*
hexley	0:281d6ff68967	662	* Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
hexley	0:281d6ff68967	663	* is harmless
hexley	0:281d6ff68967	664	*/
hexley	0:281d6ff68967	665	if (last_unsent == NULL) {
hexley	0:281d6ff68967	666	pcb->unsent = queue;
hexley	0:281d6ff68967	667	} else {
hexley	0:281d6ff68967	668	last_unsent->next = queue;
hexley	0:281d6ff68967	669	}
hexley	0:281d6ff68967	670
hexley	0:281d6ff68967	671	/*
hexley	0:281d6ff68967	672	* Finally update the pcb state.
hexley	0:281d6ff68967	673	*/
hexley	0:281d6ff68967	674	pcb->snd_lbb += len;
hexley	0:281d6ff68967	675	pcb->snd_buf -= len;
hexley	0:281d6ff68967	676	pcb->snd_queuelen = queuelen;
hexley	0:281d6ff68967	677
hexley	0:281d6ff68967	678	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
hexley	0:281d6ff68967	679	pcb->snd_queuelen));
hexley	0:281d6ff68967	680	if (pcb->snd_queuelen != 0) {
hexley	0:281d6ff68967	681	LWIP_ASSERT("tcp_write: valid queue length",
hexley	0:281d6ff68967	682	pcb->unacked != NULL \|\| pcb->unsent != NULL);
hexley	0:281d6ff68967	683	}
hexley	0:281d6ff68967	684
hexley	0:281d6ff68967	685	/* Set the PSH flag in the last segment that we enqueued. */
hexley	0:281d6ff68967	686	if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
hexley	0:281d6ff68967	687	TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
hexley	0:281d6ff68967	688	}
hexley	0:281d6ff68967	689
hexley	0:281d6ff68967	690	return ERR_OK;
hexley	0:281d6ff68967	691	memerr:
hexley	0:281d6ff68967	692	pcb->flags \|= TF_NAGLEMEMERR;
hexley	0:281d6ff68967	693	TCP_STATS_INC(tcp.memerr);
hexley	0:281d6ff68967	694
hexley	0:281d6ff68967	695	if (concat_p != NULL) {
hexley	0:281d6ff68967	696	pbuf_free(concat_p);
hexley	0:281d6ff68967	697	}
hexley	0:281d6ff68967	698	if (queue != NULL) {
hexley	0:281d6ff68967	699	tcp_segs_free(queue);
hexley	0:281d6ff68967	700	}
hexley	0:281d6ff68967	701	if (pcb->snd_queuelen != 0) {
hexley	0:281d6ff68967	702	LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL \|\|
hexley	0:281d6ff68967	703	pcb->unsent != NULL);
hexley	0:281d6ff68967	704	}
hexley	0:281d6ff68967	705	LWIP_DEBUGF(TCP_QLEN_DEBUG \| LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
hexley	0:281d6ff68967	706	return ERR_MEM;
hexley	0:281d6ff68967	707	}
hexley	0:281d6ff68967	708
hexley	0:281d6ff68967	709	/**
hexley	0:281d6ff68967	710	* Enqueue TCP options for transmission.
hexley	0:281d6ff68967	711	*
hexley	0:281d6ff68967	712	* Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
hexley	0:281d6ff68967	713	*
hexley	0:281d6ff68967	714	* @param pcb Protocol control block for the TCP connection.
hexley	0:281d6ff68967	715	* @param flags TCP header flags to set in the outgoing segment.
hexley	0:281d6ff68967	716	* @param optdata pointer to TCP options, or NULL.
hexley	0:281d6ff68967	717	* @param optlen length of TCP options in bytes.
hexley	0:281d6ff68967	718	*/
hexley	0:281d6ff68967	719	err_t
hexley	0:281d6ff68967	720	tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
hexley	0:281d6ff68967	721	{
hexley	0:281d6ff68967	722	struct pbuf *p;
hexley	0:281d6ff68967	723	struct tcp_seg *seg;
hexley	0:281d6ff68967	724	u8_t optflags = 0;
hexley	0:281d6ff68967	725	u8_t optlen = 0;
hexley	0:281d6ff68967	726
hexley	0:281d6ff68967	727	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
hexley	0:281d6ff68967	728
hexley	0:281d6ff68967	729	LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
hexley	0:281d6ff68967	730	(flags & (TCP_SYN \| TCP_FIN)) != 0);
hexley	0:281d6ff68967	731
hexley	0:281d6ff68967	732	/* check for configured max queuelen and possible overflow */
hexley	0:281d6ff68967	733	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
hexley	0:281d6ff68967	734	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
hexley	0:281d6ff68967	735	pcb->snd_queuelen, TCP_SND_QUEUELEN));
hexley	0:281d6ff68967	736	TCP_STATS_INC(tcp.memerr);
hexley	0:281d6ff68967	737	pcb->flags \|= TF_NAGLEMEMERR;
hexley	0:281d6ff68967	738	return ERR_MEM;
hexley	0:281d6ff68967	739	}
hexley	0:281d6ff68967	740
hexley	0:281d6ff68967	741	if (flags & TCP_SYN) {
hexley	0:281d6ff68967	742	optflags = TF_SEG_OPTS_MSS;
hexley	0:281d6ff68967	743	}
hexley	0:281d6ff68967	744	#if LWIP_TCP_TIMESTAMPS
hexley	0:281d6ff68967	745	if ((pcb->flags & TF_TIMESTAMP)) {
hexley	0:281d6ff68967	746	optflags \|= TF_SEG_OPTS_TS;
hexley	0:281d6ff68967	747	}
hexley	0:281d6ff68967	748	#endif /* LWIP_TCP_TIMESTAMPS */
hexley	0:281d6ff68967	749	optlen = LWIP_TCP_OPT_LENGTH(optflags);
hexley	0:281d6ff68967	750
hexley	0:281d6ff68967	751	/* tcp_enqueue_flags is always called with either SYN or FIN in flags.
hexley	0:281d6ff68967	752	* We need one available snd_buf byte to do that.
hexley	0:281d6ff68967	753	* This means we can't send FIN while snd_buf==0. A better fix would be to
hexley	0:281d6ff68967	754	* not include SYN and FIN sequence numbers in the snd_buf count. */
hexley	0:281d6ff68967	755	if (pcb->snd_buf == 0) {
hexley	0:281d6ff68967	756	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: no send buffer available\n"));
hexley	0:281d6ff68967	757	TCP_STATS_INC(tcp.memerr);
hexley	0:281d6ff68967	758	return ERR_MEM;
hexley	0:281d6ff68967	759	}
hexley	0:281d6ff68967	760
hexley	0:281d6ff68967	761	/* Allocate pbuf with room for TCP header + options */
hexley	0:281d6ff68967	762	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
hexley	0:281d6ff68967	763	pcb->flags \|= TF_NAGLEMEMERR;
hexley	0:281d6ff68967	764	TCP_STATS_INC(tcp.memerr);
hexley	0:281d6ff68967	765	return ERR_MEM;
hexley	0:281d6ff68967	766	}
hexley	0:281d6ff68967	767	LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
hexley	0:281d6ff68967	768	(p->len >= optlen));
hexley	0:281d6ff68967	769
hexley	0:281d6ff68967	770	/* Allocate memory for tcp_seg, and fill in fields. */
hexley	0:281d6ff68967	771	if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
hexley	0:281d6ff68967	772	pcb->flags \|= TF_NAGLEMEMERR;
hexley	0:281d6ff68967	773	TCP_STATS_INC(tcp.memerr);
hexley	0:281d6ff68967	774	return ERR_MEM;
hexley	0:281d6ff68967	775	}
hexley	0:281d6ff68967	776	LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
hexley	0:281d6ff68967	777
hexley	0:281d6ff68967	778	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE,
hexley	0:281d6ff68967	779	("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
hexley	0:281d6ff68967	780	ntohl(seg->tcphdr->seqno),
hexley	0:281d6ff68967	781	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
hexley	0:281d6ff68967	782	(u16_t)flags));
hexley	0:281d6ff68967	783
hexley	0:281d6ff68967	784	/* Now append seg to pcb->unsent queue */
hexley	0:281d6ff68967	785	if (pcb->unsent == NULL) {
hexley	0:281d6ff68967	786	pcb->unsent = seg;
hexley	0:281d6ff68967	787	} else {
hexley	0:281d6ff68967	788	struct tcp_seg *useg;
hexley	0:281d6ff68967	789	for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
hexley	0:281d6ff68967	790	useg->next = seg;
hexley	0:281d6ff68967	791	}
hexley	0:281d6ff68967	792	#if TCP_OVERSIZE
hexley	0:281d6ff68967	793	/* The new unsent tail has no space */
hexley	0:281d6ff68967	794	pcb->unsent_oversize = 0;
hexley	0:281d6ff68967	795	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	796
hexley	0:281d6ff68967	797	/* SYN and FIN bump the sequence number */
hexley	0:281d6ff68967	798	if ((flags & TCP_SYN) \|\| (flags & TCP_FIN)) {
hexley	0:281d6ff68967	799	pcb->snd_lbb++;
hexley	0:281d6ff68967	800	/* optlen does not influence snd_buf */
hexley	0:281d6ff68967	801	pcb->snd_buf--;
hexley	0:281d6ff68967	802	}
hexley	0:281d6ff68967	803	if (flags & TCP_FIN) {
hexley	0:281d6ff68967	804	pcb->flags \|= TF_FIN;
hexley	0:281d6ff68967	805	}
hexley	0:281d6ff68967	806
hexley	0:281d6ff68967	807	/* update number of segments on the queues */
hexley	0:281d6ff68967	808	pcb->snd_queuelen += pbuf_clen(seg->p);
hexley	0:281d6ff68967	809	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
hexley	0:281d6ff68967	810	if (pcb->snd_queuelen != 0) {
hexley	0:281d6ff68967	811	LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
hexley	0:281d6ff68967	812	pcb->unacked != NULL \|\| pcb->unsent != NULL);
hexley	0:281d6ff68967	813	}
hexley	0:281d6ff68967	814
hexley	0:281d6ff68967	815	return ERR_OK;
hexley	0:281d6ff68967	816	}
hexley	0:281d6ff68967	817
hexley	0:281d6ff68967	818
hexley	0:281d6ff68967	819	#if LWIP_TCP_TIMESTAMPS
hexley	0:281d6ff68967	820	/* Build a timestamp option (12 bytes long) at the specified options pointer)
hexley	0:281d6ff68967	821	*
hexley	0:281d6ff68967	822	* @param pcb tcp_pcb
hexley	0:281d6ff68967	823	* @param opts option pointer where to store the timestamp option
hexley	0:281d6ff68967	824	*/
hexley	0:281d6ff68967	825	static void
hexley	0:281d6ff68967	826	tcp_build_timestamp_option(struct tcp_pcb pcb, u32_t opts)
hexley	0:281d6ff68967	827	{
hexley	0:281d6ff68967	828	/* Pad with two NOP options to make everything nicely aligned */
hexley	0:281d6ff68967	829	opts[0] = PP_HTONL(0x0101080A);
hexley	0:281d6ff68967	830	opts[1] = htonl(sys_now());
hexley	0:281d6ff68967	831	opts[2] = htonl(pcb->ts_recent);
hexley	0:281d6ff68967	832	}
hexley	0:281d6ff68967	833	#endif
hexley	0:281d6ff68967	834
hexley	0:281d6ff68967	835	/** Send an ACK without data.
hexley	0:281d6ff68967	836	*
hexley	0:281d6ff68967	837	* @param pcb Protocol control block for the TCP connection to send the ACK
hexley	0:281d6ff68967	838	*/
hexley	0:281d6ff68967	839	err_t
hexley	0:281d6ff68967	840	tcp_send_empty_ack(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	841	{
hexley	0:281d6ff68967	842	struct pbuf *p;
hexley	0:281d6ff68967	843	struct tcp_hdr *tcphdr;
hexley	0:281d6ff68967	844	u8_t optlen = 0;
hexley	0:281d6ff68967	845
hexley	0:281d6ff68967	846	#if LWIP_TCP_TIMESTAMPS
hexley	0:281d6ff68967	847	if (pcb->flags & TF_TIMESTAMP) {
hexley	0:281d6ff68967	848	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
hexley	0:281d6ff68967	849	}
hexley	0:281d6ff68967	850	#endif
hexley	0:281d6ff68967	851
hexley	0:281d6ff68967	852	p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
hexley	0:281d6ff68967	853	if (p == NULL) {
hexley	0:281d6ff68967	854	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
hexley	0:281d6ff68967	855	return ERR_BUF;
hexley	0:281d6ff68967	856	}
hexley	0:281d6ff68967	857	tcphdr = (struct tcp_hdr *)p->payload;
hexley	0:281d6ff68967	858	LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
hexley	0:281d6ff68967	859	("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
hexley	0:281d6ff68967	860	/* remove ACK flags from the PCB, as we send an empty ACK now */
hexley	0:281d6ff68967	861	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
hexley	0:281d6ff68967	862
hexley	0:281d6ff68967	863	/* NB. MSS option is only sent on SYNs, so ignore it here */
hexley	0:281d6ff68967	864	#if LWIP_TCP_TIMESTAMPS
hexley	0:281d6ff68967	865	pcb->ts_lastacksent = pcb->rcv_nxt;
hexley	0:281d6ff68967	866
hexley	0:281d6ff68967	867	if (pcb->flags & TF_TIMESTAMP) {
hexley	0:281d6ff68967	868	tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
hexley	0:281d6ff68967	869	}
hexley	0:281d6ff68967	870	#endif
hexley	0:281d6ff68967	871
hexley	0:281d6ff68967	872	#if CHECKSUM_GEN_TCP
hexley	0:281d6ff68967	873	tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
hexley	0:281d6ff68967	874	IP_PROTO_TCP, p->tot_len);
hexley	0:281d6ff68967	875	#endif
hexley	0:281d6ff68967	876	#if LWIP_NETIF_HWADDRHINT
hexley	0:281d6ff68967	877	ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
hexley	0:281d6ff68967	878	IP_PROTO_TCP, &(pcb->addr_hint));
hexley	0:281d6ff68967	879	#else /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	880	ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
hexley	0:281d6ff68967	881	IP_PROTO_TCP);
hexley	0:281d6ff68967	882	#endif /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	883	pbuf_free(p);
hexley	0:281d6ff68967	884
hexley	0:281d6ff68967	885	return ERR_OK;
hexley	0:281d6ff68967	886	}
hexley	0:281d6ff68967	887
hexley	0:281d6ff68967	888	/**
hexley	0:281d6ff68967	889	* Find out what we can send and send it
hexley	0:281d6ff68967	890	*
hexley	0:281d6ff68967	891	* @param pcb Protocol control block for the TCP connection to send data
hexley	0:281d6ff68967	892	* @return ERR_OK if data has been sent or nothing to send
hexley	0:281d6ff68967	893	* another err_t on error
hexley	0:281d6ff68967	894	*/
hexley	0:281d6ff68967	895	err_t
hexley	0:281d6ff68967	896	tcp_output(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	897	{
hexley	0:281d6ff68967	898	struct tcp_seg seg, useg;
hexley	0:281d6ff68967	899	u32_t wnd, snd_nxt;
hexley	0:281d6ff68967	900	#if TCP_CWND_DEBUG
hexley	0:281d6ff68967	901	s16_t i = 0;
hexley	0:281d6ff68967	902	#endif /* TCP_CWND_DEBUG */
hexley	0:281d6ff68967	903
hexley	0:281d6ff68967	904	/* First, check if we are invoked by the TCP input processing
hexley	0:281d6ff68967	905	code. If so, we do not output anything. Instead, we rely on the
hexley	0:281d6ff68967	906	input processing code to call us when input processing is done
hexley	0:281d6ff68967	907	with. */
hexley	0:281d6ff68967	908	if (tcp_input_pcb == pcb) {
hexley	0:281d6ff68967	909	return ERR_OK;
hexley	0:281d6ff68967	910	}
hexley	0:281d6ff68967	911
hexley	0:281d6ff68967	912	wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
hexley	0:281d6ff68967	913
hexley	0:281d6ff68967	914	seg = pcb->unsent;
hexley	0:281d6ff68967	915
hexley	0:281d6ff68967	916	/* If the TF_ACK_NOW flag is set and no data will be sent (either
hexley	0:281d6ff68967	917	* because the ->unsent queue is empty or because the window does
hexley	0:281d6ff68967	918	* not allow it), construct an empty ACK segment and send it.
hexley	0:281d6ff68967	919	*
hexley	0:281d6ff68967	920	* If data is to be sent, we will just piggyback the ACK (see below).
hexley	0:281d6ff68967	921	*/
hexley	0:281d6ff68967	922	if (pcb->flags & TF_ACK_NOW &&
hexley	0:281d6ff68967	923	(seg == NULL \|\|
hexley	0:281d6ff68967	924	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
hexley	0:281d6ff68967	925	return tcp_send_empty_ack(pcb);
hexley	0:281d6ff68967	926	}
hexley	0:281d6ff68967	927
hexley	0:281d6ff68967	928	/* useg should point to last segment on unacked queue */
hexley	0:281d6ff68967	929	useg = pcb->unacked;
hexley	0:281d6ff68967	930	if (useg != NULL) {
hexley	0:281d6ff68967	931	for (; useg->next != NULL; useg = useg->next);
hexley	0:281d6ff68967	932	}
hexley	0:281d6ff68967	933
hexley	0:281d6ff68967	934	#if TCP_OUTPUT_DEBUG
hexley	0:281d6ff68967	935	if (seg == NULL) {
hexley	0:281d6ff68967	936	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
hexley	0:281d6ff68967	937	(void*)pcb->unsent));
hexley	0:281d6ff68967	938	}
hexley	0:281d6ff68967	939	#endif /* TCP_OUTPUT_DEBUG */
hexley	0:281d6ff68967	940	#if TCP_CWND_DEBUG
hexley	0:281d6ff68967	941	if (seg == NULL) {
hexley	0:281d6ff68967	942	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
hexley	0:281d6ff68967	943	", cwnd %"U16_F", wnd %"U32_F
hexley	0:281d6ff68967	944	", seg == NULL, ack %"U32_F"\n",
hexley	0:281d6ff68967	945	pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
hexley	0:281d6ff68967	946	} else {
hexley	0:281d6ff68967	947	LWIP_DEBUGF(TCP_CWND_DEBUG,
hexley	0:281d6ff68967	948	("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
hexley	0:281d6ff68967	949	", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
hexley	0:281d6ff68967	950	pcb->snd_wnd, pcb->cwnd, wnd,
hexley	0:281d6ff68967	951	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
hexley	0:281d6ff68967	952	ntohl(seg->tcphdr->seqno), pcb->lastack));
hexley	0:281d6ff68967	953	}
hexley	0:281d6ff68967	954	#endif /* TCP_CWND_DEBUG */
hexley	0:281d6ff68967	955	/* data available and window allows it to be sent? */
hexley	0:281d6ff68967	956	while (seg != NULL &&
hexley	0:281d6ff68967	957	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
hexley	0:281d6ff68967	958	LWIP_ASSERT("RST not expected here!",
hexley	0:281d6ff68967	959	(TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
hexley	0:281d6ff68967	960	/* Stop sending if the nagle algorithm would prevent it
hexley	0:281d6ff68967	961	* Don't stop:
hexley	0:281d6ff68967	962	* - if tcp_write had a memory error before (prevent delayed ACK timeout) or
hexley	0:281d6ff68967	963	* - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
hexley	0:281d6ff68967	964	* either seg->next != NULL or pcb->unacked == NULL;
hexley	0:281d6ff68967	965	* RST is no sent using tcp_write/tcp_output.
hexley	0:281d6ff68967	966	*/
hexley	0:281d6ff68967	967	if((tcp_do_output_nagle(pcb) == 0) &&
hexley	0:281d6ff68967	968	((pcb->flags & (TF_NAGLEMEMERR \| TF_FIN)) == 0)){
hexley	0:281d6ff68967	969	break;
hexley	0:281d6ff68967	970	}
hexley	0:281d6ff68967	971	#if TCP_CWND_DEBUG
hexley	0:281d6ff68967	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",
hexley	0:281d6ff68967	973	pcb->snd_wnd, pcb->cwnd, wnd,
hexley	0:281d6ff68967	974	ntohl(seg->tcphdr->seqno) + seg->len -
hexley	0:281d6ff68967	975	pcb->lastack,
hexley	0:281d6ff68967	976	ntohl(seg->tcphdr->seqno), pcb->lastack, i));
hexley	0:281d6ff68967	977	++i;
hexley	0:281d6ff68967	978	#endif /* TCP_CWND_DEBUG */
hexley	0:281d6ff68967	979
hexley	0:281d6ff68967	980	pcb->unsent = seg->next;
hexley	0:281d6ff68967	981
hexley	0:281d6ff68967	982	if (pcb->state != SYN_SENT) {
hexley	0:281d6ff68967	983	TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
hexley	0:281d6ff68967	984	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
hexley	0:281d6ff68967	985	}
hexley	0:281d6ff68967	986
hexley	0:281d6ff68967	987	tcp_output_segment(seg, pcb);
hexley	0:281d6ff68967	988
hexley	0:281d6ff68967	989	snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
hexley	0:281d6ff68967	990
hexley	0:281d6ff68967	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
hexley	0:281d6ff68967	992	pcb->snd_nxt, ntohl(seg->tcphdr->seqno), TCP_TCPLEN(seg), snd_nxt));
hexley	0:281d6ff68967	993
hexley	0:281d6ff68967	994	if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
hexley	0:281d6ff68967	995	pcb->snd_nxt = snd_nxt;
hexley	0:281d6ff68967	996	}
hexley	0:281d6ff68967	997	/* put segment on unacknowledged list if length > 0 */
hexley	0:281d6ff68967	998	if (TCP_TCPLEN(seg) > 0) {
hexley	0:281d6ff68967	999	seg->next = NULL;
hexley	0:281d6ff68967	1000	/* unacked list is empty? */
hexley	0:281d6ff68967	1001	if (pcb->unacked == NULL) {
hexley	0:281d6ff68967	1002	pcb->unacked = seg;
hexley	0:281d6ff68967	1003	useg = seg;
hexley	0:281d6ff68967	1004	/* unacked list is not empty? */
hexley	0:281d6ff68967	1005	} else {
hexley	0:281d6ff68967	1006	/* In the case of fast retransmit, the packet should not go to the tail
hexley	0:281d6ff68967	1007	* of the unacked queue, but rather somewhere before it. We need to check for
hexley	0:281d6ff68967	1008	* this case. -STJ Jul 27, 2004 */
hexley	0:281d6ff68967	1009	if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
hexley	0:281d6ff68967	1010	/* add segment to before tail of unacked list, keeping the list sorted */
hexley	0:281d6ff68967	1011	struct tcp_seg **cur_seg = &(pcb->unacked);
hexley	0:281d6ff68967	1012	while (*cur_seg &&
hexley	0:281d6ff68967	1013	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
hexley	0:281d6ff68967	1014	cur_seg = &((*cur_seg)->next );
hexley	0:281d6ff68967	1015	}
hexley	0:281d6ff68967	1016	seg->next = (*cur_seg);
hexley	0:281d6ff68967	1017	(*cur_seg) = seg;
hexley	0:281d6ff68967	1018	} else {
hexley	0:281d6ff68967	1019	/* add segment to tail of unacked list */
hexley	0:281d6ff68967	1020	useg->next = seg;
hexley	0:281d6ff68967	1021	useg = useg->next;
hexley	0:281d6ff68967	1022	}
hexley	0:281d6ff68967	1023	}
hexley	0:281d6ff68967	1024	/* do not queue empty segments on the unacked list */
hexley	0:281d6ff68967	1025	} else {
hexley	0:281d6ff68967	1026	tcp_seg_free(seg);
hexley	0:281d6ff68967	1027	}
hexley	0:281d6ff68967	1028	seg = pcb->unsent;
hexley	0:281d6ff68967	1029	}
hexley	0:281d6ff68967	1030	#if TCP_OVERSIZE
hexley	0:281d6ff68967	1031	if (pcb->unsent == NULL) {
hexley	0:281d6ff68967	1032	/* last unsent has been removed, reset unsent_oversize */
hexley	0:281d6ff68967	1033	pcb->unsent_oversize = 0;
hexley	0:281d6ff68967	1034	}
hexley	0:281d6ff68967	1035	#endif /* TCP_OVERSIZE */
hexley	0:281d6ff68967	1036
hexley	0:281d6ff68967	1037	if (seg != NULL && pcb->persist_backoff == 0 &&
hexley	0:281d6ff68967	1038	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) {
hexley	0:281d6ff68967	1039	/* prepare for persist timer */
hexley	0:281d6ff68967	1040	pcb->persist_cnt = 0;
hexley	0:281d6ff68967	1041	pcb->persist_backoff = 1;
hexley	0:281d6ff68967	1042	}
hexley	0:281d6ff68967	1043
hexley	0:281d6ff68967	1044	pcb->flags &= ~TF_NAGLEMEMERR;
hexley	0:281d6ff68967	1045	return ERR_OK;
hexley	0:281d6ff68967	1046	}
hexley	0:281d6ff68967	1047
hexley	0:281d6ff68967	1048	/**
hexley	0:281d6ff68967	1049	* Called by tcp_output() to actually send a TCP segment over IP.
hexley	0:281d6ff68967	1050	*
hexley	0:281d6ff68967	1051	* @param seg the tcp_seg to send
hexley	0:281d6ff68967	1052	* @param pcb the tcp_pcb for the TCP connection used to send the segment
hexley	0:281d6ff68967	1053	*/
hexley	0:281d6ff68967	1054	static void
hexley	0:281d6ff68967	1055	tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb)
hexley	0:281d6ff68967	1056	{
hexley	0:281d6ff68967	1057	u16_t len;
hexley	0:281d6ff68967	1058	struct netif *netif;
hexley	0:281d6ff68967	1059	u32_t *opts;
hexley	0:281d6ff68967	1060
hexley	0:281d6ff68967	1061	/** @bug Exclude retransmitted segments from this count. */
hexley	0:281d6ff68967	1062	snmp_inc_tcpoutsegs();
hexley	0:281d6ff68967	1063
hexley	0:281d6ff68967	1064	/* The TCP header has already been constructed, but the ackno and
hexley	0:281d6ff68967	1065	wnd fields remain. */
hexley	0:281d6ff68967	1066	seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
hexley	0:281d6ff68967	1067
hexley	0:281d6ff68967	1068	/* advertise our receive window size in this TCP segment */
hexley	0:281d6ff68967	1069	seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
hexley	0:281d6ff68967	1070
hexley	0:281d6ff68967	1071	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
hexley	0:281d6ff68967	1072
hexley	0:281d6ff68967	1073	/* Add any requested options. NB MSS option is only set on SYN
hexley	0:281d6ff68967	1074	packets, so ignore it here */
hexley	0:281d6ff68967	1075	LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
hexley	0:281d6ff68967	1076	opts = (u32_t )(void )(seg->tcphdr + 1);
hexley	0:281d6ff68967	1077	if (seg->flags & TF_SEG_OPTS_MSS) {
hexley	0:281d6ff68967	1078	TCP_BUILD_MSS_OPTION(*opts);
hexley	0:281d6ff68967	1079	opts += 1;
hexley	0:281d6ff68967	1080	}
hexley	0:281d6ff68967	1081	#if LWIP_TCP_TIMESTAMPS
hexley	0:281d6ff68967	1082	pcb->ts_lastacksent = pcb->rcv_nxt;
hexley	0:281d6ff68967	1083
hexley	0:281d6ff68967	1084	if (seg->flags & TF_SEG_OPTS_TS) {
hexley	0:281d6ff68967	1085	tcp_build_timestamp_option(pcb, opts);
hexley	0:281d6ff68967	1086	opts += 3;
hexley	0:281d6ff68967	1087	}
hexley	0:281d6ff68967	1088	#endif
hexley	0:281d6ff68967	1089
hexley	0:281d6ff68967	1090	/* If we don't have a local IP address, we get one by
hexley	0:281d6ff68967	1091	calling ip_route(). */
hexley	0:281d6ff68967	1092	if (ip_addr_isany(&(pcb->local_ip))) {
hexley	0:281d6ff68967	1093	netif = ip_route(&(pcb->remote_ip));
hexley	0:281d6ff68967	1094	if (netif == NULL) {
hexley	0:281d6ff68967	1095	return;
hexley	0:281d6ff68967	1096	}
hexley	0:281d6ff68967	1097	ip_addr_copy(pcb->local_ip, netif->ip_addr);
hexley	0:281d6ff68967	1098	}
hexley	0:281d6ff68967	1099
hexley	0:281d6ff68967	1100	/* Set retransmission timer running if it is not currently enabled */
hexley	0:281d6ff68967	1101	if(pcb->rtime == -1) {
hexley	0:281d6ff68967	1102	pcb->rtime = 0;
hexley	0:281d6ff68967	1103	}
hexley	0:281d6ff68967	1104
hexley	0:281d6ff68967	1105	if (pcb->rttest == 0) {
hexley	0:281d6ff68967	1106	pcb->rttest = tcp_ticks;
hexley	0:281d6ff68967	1107	pcb->rtseq = ntohl(seg->tcphdr->seqno);
hexley	0:281d6ff68967	1108
hexley	0:281d6ff68967	1109	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
hexley	0:281d6ff68967	1110	}
hexley	0:281d6ff68967	1111	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
hexley	0:281d6ff68967	1112	htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
hexley	0:281d6ff68967	1113	seg->len));
hexley	0:281d6ff68967	1114
hexley	0:281d6ff68967	1115	len = (u16_t)((u8_t )seg->tcphdr - (u8_t )seg->p->payload);
hexley	0:281d6ff68967	1116
hexley	0:281d6ff68967	1117	seg->p->len -= len;
hexley	0:281d6ff68967	1118	seg->p->tot_len -= len;
hexley	0:281d6ff68967	1119
hexley	0:281d6ff68967	1120	seg->p->payload = seg->tcphdr;
hexley	0:281d6ff68967	1121
hexley	0:281d6ff68967	1122	seg->tcphdr->chksum = 0;
hexley	0:281d6ff68967	1123	#if CHECKSUM_GEN_TCP
hexley	0:281d6ff68967	1124	#if TCP_CHECKSUM_ON_COPY
hexley	0:281d6ff68967	1125	{
hexley	0:281d6ff68967	1126	u32_t acc;
hexley	0:281d6ff68967	1127	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
hexley	0:281d6ff68967	1128	u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
hexley	0:281d6ff68967	1129	&(pcb->remote_ip),
hexley	0:281d6ff68967	1130	IP_PROTO_TCP, seg->p->tot_len);
hexley	0:281d6ff68967	1131	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
hexley	0:281d6ff68967	1132	if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
hexley	0:281d6ff68967	1133	LWIP_ASSERT("data included but not checksummed",
hexley	0:281d6ff68967	1134	seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
hexley	0:281d6ff68967	1135	}
hexley	0:281d6ff68967	1136
hexley	0:281d6ff68967	1137	/* rebuild TCP header checksum (TCP header changes for retransmissions!) */
hexley	0:281d6ff68967	1138	acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
hexley	0:281d6ff68967	1139	&(pcb->remote_ip),
hexley	0:281d6ff68967	1140	IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
hexley	0:281d6ff68967	1141	/* add payload checksum */
hexley	0:281d6ff68967	1142	if (seg->chksum_swapped) {
hexley	0:281d6ff68967	1143	seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
hexley	0:281d6ff68967	1144	seg->chksum_swapped = 0;
hexley	0:281d6ff68967	1145	}
hexley	0:281d6ff68967	1146	acc += (u16_t)~(seg->chksum);
hexley	0:281d6ff68967	1147	seg->tcphdr->chksum = FOLD_U32T(acc);
hexley	0:281d6ff68967	1148	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
hexley	0:281d6ff68967	1149	if (chksum_slow != seg->tcphdr->chksum) {
hexley	0:281d6ff68967	1150	LWIP_DEBUGF(TCP_DEBUG \| LWIP_DBG_LEVEL_WARNING,
hexley	0:281d6ff68967	1151	("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
hexley	0:281d6ff68967	1152	seg->tcphdr->chksum, chksum_slow));
hexley	0:281d6ff68967	1153	seg->tcphdr->chksum = chksum_slow;
hexley	0:281d6ff68967	1154	}
hexley	0:281d6ff68967	1155	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
hexley	0:281d6ff68967	1156	}
hexley	0:281d6ff68967	1157	#else /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	1158	seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
hexley	0:281d6ff68967	1159	&(pcb->remote_ip),
hexley	0:281d6ff68967	1160	IP_PROTO_TCP, seg->p->tot_len);
hexley	0:281d6ff68967	1161	#endif /* TCP_CHECKSUM_ON_COPY */
hexley	0:281d6ff68967	1162	#endif /* CHECKSUM_GEN_TCP */
hexley	0:281d6ff68967	1163	TCP_STATS_INC(tcp.xmit);
hexley	0:281d6ff68967	1164
hexley	0:281d6ff68967	1165	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: Before ip_out seqno = %"U32_F"\n",
hexley	0:281d6ff68967	1166	htonl(seg->tcphdr->seqno))); //DG
hexley	0:281d6ff68967	1167
hexley	0:281d6ff68967	1168	#if LWIP_NETIF_HWADDRHINT
hexley	0:281d6ff68967	1169	ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
hexley	0:281d6ff68967	1170	IP_PROTO_TCP, &(pcb->addr_hint));
hexley	0:281d6ff68967	1171	#else /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	1172	ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
hexley	0:281d6ff68967	1173	IP_PROTO_TCP);
hexley	0:281d6ff68967	1174	#endif /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	1175
hexley	0:281d6ff68967	1176	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: After ip_out seqno = %"U32_F"\n",
hexley	0:281d6ff68967	1177	htonl(seg->tcphdr->seqno))); //DG
hexley	0:281d6ff68967	1178
hexley	0:281d6ff68967	1179
hexley	0:281d6ff68967	1180	}
hexley	0:281d6ff68967	1181
hexley	0:281d6ff68967	1182	/**
hexley	0:281d6ff68967	1183	* Send a TCP RESET packet (empty segment with RST flag set) either to
hexley	0:281d6ff68967	1184	* abort a connection or to show that there is no matching local connection
hexley	0:281d6ff68967	1185	* for a received segment.
hexley	0:281d6ff68967	1186	*
hexley	0:281d6ff68967	1187	* Called by tcp_abort() (to abort a local connection), tcp_input() (if no
hexley	0:281d6ff68967	1188	* matching local pcb was found), tcp_listen_input() (if incoming segment
hexley	0:281d6ff68967	1189	* has ACK flag set) and tcp_process() (received segment in the wrong state)
hexley	0:281d6ff68967	1190	*
hexley	0:281d6ff68967	1191	* Since a RST segment is in most cases not sent for an active connection,
hexley	0:281d6ff68967	1192	* tcp_rst() has a number of arguments that are taken from a tcp_pcb for
hexley	0:281d6ff68967	1193	* most other segment output functions.
hexley	0:281d6ff68967	1194	*
hexley	0:281d6ff68967	1195	* @param seqno the sequence number to use for the outgoing segment
hexley	0:281d6ff68967	1196	* @param ackno the acknowledge number to use for the outgoing segment
hexley	0:281d6ff68967	1197	* @param local_ip the local IP address to send the segment from
hexley	0:281d6ff68967	1198	* @param remote_ip the remote IP address to send the segment to
hexley	0:281d6ff68967	1199	* @param local_port the local TCP port to send the segment from
hexley	0:281d6ff68967	1200	* @param remote_port the remote TCP port to send the segment to
hexley	0:281d6ff68967	1201	*/
hexley	0:281d6ff68967	1202	void
hexley	0:281d6ff68967	1203	tcp_rst(u32_t seqno, u32_t ackno,
hexley	0:281d6ff68967	1204	ip_addr_t local_ip, ip_addr_t remote_ip,
hexley	0:281d6ff68967	1205	u16_t local_port, u16_t remote_port)
hexley	0:281d6ff68967	1206	{
hexley	0:281d6ff68967	1207	struct pbuf *p;
hexley	0:281d6ff68967	1208	struct tcp_hdr *tcphdr;
hexley	0:281d6ff68967	1209	p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
hexley	0:281d6ff68967	1210	if (p == NULL) {
hexley	0:281d6ff68967	1211	LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
hexley	0:281d6ff68967	1212	return;
hexley	0:281d6ff68967	1213	}
hexley	0:281d6ff68967	1214	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
hexley	0:281d6ff68967	1215	(p->len >= sizeof(struct tcp_hdr)));
hexley	0:281d6ff68967	1216
hexley	0:281d6ff68967	1217	tcphdr = (struct tcp_hdr *)p->payload;
hexley	0:281d6ff68967	1218	tcphdr->src = htons(local_port);
hexley	0:281d6ff68967	1219	tcphdr->dest = htons(remote_port);
hexley	0:281d6ff68967	1220	tcphdr->seqno = htonl(seqno);
hexley	0:281d6ff68967	1221	tcphdr->ackno = htonl(ackno);
hexley	0:281d6ff68967	1222	TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST \| TCP_ACK);
hexley	0:281d6ff68967	1223	tcphdr->wnd = PP_HTONS(TCP_WND);
hexley	0:281d6ff68967	1224	tcphdr->chksum = 0;
hexley	0:281d6ff68967	1225	tcphdr->urgp = 0;
hexley	0:281d6ff68967	1226
hexley	0:281d6ff68967	1227	#if CHECKSUM_GEN_TCP
hexley	0:281d6ff68967	1228	tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
hexley	0:281d6ff68967	1229	IP_PROTO_TCP, p->tot_len);
hexley	0:281d6ff68967	1230	#endif
hexley	0:281d6ff68967	1231	TCP_STATS_INC(tcp.xmit);
hexley	0:281d6ff68967	1232	snmp_inc_tcpoutrsts();
hexley	0:281d6ff68967	1233	/* Send output with hardcoded TTL since we have no access to the pcb */
hexley	0:281d6ff68967	1234	ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
hexley	0:281d6ff68967	1235	pbuf_free(p);
hexley	0:281d6ff68967	1236	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
hexley	0:281d6ff68967	1237	}
hexley	0:281d6ff68967	1238
hexley	0:281d6ff68967	1239	/**
hexley	0:281d6ff68967	1240	* Requeue all unacked segments for retransmission
hexley	0:281d6ff68967	1241	*
hexley	0:281d6ff68967	1242	* Called by tcp_slowtmr() for slow retransmission.
hexley	0:281d6ff68967	1243	*
hexley	0:281d6ff68967	1244	* @param pcb the tcp_pcb for which to re-enqueue all unacked segments
hexley	0:281d6ff68967	1245	*/
hexley	0:281d6ff68967	1246	void
hexley	0:281d6ff68967	1247	tcp_rexmit_rto(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	1248	{
hexley	0:281d6ff68967	1249	struct tcp_seg *seg;
hexley	0:281d6ff68967	1250
hexley	0:281d6ff68967	1251	if (pcb->unacked == NULL) {
hexley	0:281d6ff68967	1252	return;
hexley	0:281d6ff68967	1253	}
hexley	0:281d6ff68967	1254
hexley	0:281d6ff68967	1255	/* Move all unacked segments to the head of the unsent queue */
hexley	0:281d6ff68967	1256	for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
hexley	0:281d6ff68967	1257	/* concatenate unsent queue after unacked queue */
hexley	0:281d6ff68967	1258	seg->next = pcb->unsent;
hexley	0:281d6ff68967	1259	/* unsent queue is the concatenated queue (of unacked, unsent) */
hexley	0:281d6ff68967	1260	pcb->unsent = pcb->unacked;
hexley	0:281d6ff68967	1261	/* unacked queue is now empty */
hexley	0:281d6ff68967	1262	pcb->unacked = NULL;
hexley	0:281d6ff68967	1263
hexley	0:281d6ff68967	1264	/* increment number of retransmissions */
hexley	0:281d6ff68967	1265	++pcb->nrtx;
hexley	0:281d6ff68967	1266
hexley	0:281d6ff68967	1267	/* Don't take any RTT measurements after retransmitting. */
hexley	0:281d6ff68967	1268	pcb->rttest = 0;
hexley	0:281d6ff68967	1269
hexley	0:281d6ff68967	1270	/* Do the actual retransmission */
hexley	0:281d6ff68967	1271	tcp_output(pcb);
hexley	0:281d6ff68967	1272	}
hexley	0:281d6ff68967	1273
hexley	0:281d6ff68967	1274	/**
hexley	0:281d6ff68967	1275	* Requeue the first unacked segment for retransmission
hexley	0:281d6ff68967	1276	*
hexley	0:281d6ff68967	1277	* Called by tcp_receive() for fast retramsmit.
hexley	0:281d6ff68967	1278	*
hexley	0:281d6ff68967	1279	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
hexley	0:281d6ff68967	1280	*/
hexley	0:281d6ff68967	1281	void
hexley	0:281d6ff68967	1282	tcp_rexmit(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	1283	{
hexley	0:281d6ff68967	1284	struct tcp_seg *seg;
hexley	0:281d6ff68967	1285	struct tcp_seg **cur_seg;
hexley	0:281d6ff68967	1286
hexley	0:281d6ff68967	1287	if (pcb->unacked == NULL) {
hexley	0:281d6ff68967	1288	return;
hexley	0:281d6ff68967	1289	}
hexley	0:281d6ff68967	1290
hexley	0:281d6ff68967	1291	/* Move the first unacked segment to the unsent queue */
hexley	0:281d6ff68967	1292	/* Keep the unsent queue sorted. */
hexley	0:281d6ff68967	1293	seg = pcb->unacked;
hexley	0:281d6ff68967	1294	pcb->unacked = seg->next;
hexley	0:281d6ff68967	1295
hexley	0:281d6ff68967	1296	cur_seg = &(pcb->unsent);
hexley	0:281d6ff68967	1297	while (*cur_seg &&
hexley	0:281d6ff68967	1298	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
hexley	0:281d6ff68967	1299	cur_seg = &((*cur_seg)->next );
hexley	0:281d6ff68967	1300	}
hexley	0:281d6ff68967	1301	seg->next = *cur_seg;
hexley	0:281d6ff68967	1302	*cur_seg = seg;
hexley	0:281d6ff68967	1303
hexley	0:281d6ff68967	1304	++pcb->nrtx;
hexley	0:281d6ff68967	1305
hexley	0:281d6ff68967	1306	/* Don't take any rtt measurements after retransmitting. */
hexley	0:281d6ff68967	1307	pcb->rttest = 0;
hexley	0:281d6ff68967	1308
hexley	0:281d6ff68967	1309	/* Do the actual retransmission. */
hexley	0:281d6ff68967	1310	snmp_inc_tcpretranssegs();
hexley	0:281d6ff68967	1311	/* No need to call tcp_output: we are always called from tcp_input()
hexley	0:281d6ff68967	1312	and thus tcp_output directly returns. */
hexley	0:281d6ff68967	1313	}
hexley	0:281d6ff68967	1314
hexley	0:281d6ff68967	1315
hexley	0:281d6ff68967	1316	/**
hexley	0:281d6ff68967	1317	* Handle retransmission after three dupacks received
hexley	0:281d6ff68967	1318	*
hexley	0:281d6ff68967	1319	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
hexley	0:281d6ff68967	1320	*/
hexley	0:281d6ff68967	1321	void
hexley	0:281d6ff68967	1322	tcp_rexmit_fast(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	1323	{
hexley	0:281d6ff68967	1324	if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
hexley	0:281d6ff68967	1325	/* This is fast retransmit. Retransmit the first unacked segment. */
hexley	0:281d6ff68967	1326	LWIP_DEBUGF(TCP_FR_DEBUG,
hexley	0:281d6ff68967	1327	("tcp_receive: dupacks %"U16_F" (%"U32_F
hexley	0:281d6ff68967	1328	"), fast retransmit %"U32_F"\n",
hexley	0:281d6ff68967	1329	(u16_t)pcb->dupacks, pcb->lastack,
hexley	0:281d6ff68967	1330	ntohl(pcb->unacked->tcphdr->seqno)));
hexley	0:281d6ff68967	1331	tcp_rexmit(pcb);
hexley	0:281d6ff68967	1332
hexley	0:281d6ff68967	1333	/* Set ssthresh to half of the minimum of the current
hexley	0:281d6ff68967	1334	* cwnd and the advertised window */
hexley	0:281d6ff68967	1335	if (pcb->cwnd > pcb->snd_wnd) {
hexley	0:281d6ff68967	1336	pcb->ssthresh = pcb->snd_wnd / 2;
hexley	0:281d6ff68967	1337	} else {
hexley	0:281d6ff68967	1338	pcb->ssthresh = pcb->cwnd / 2;
hexley	0:281d6ff68967	1339	}
hexley	0:281d6ff68967	1340
hexley	0:281d6ff68967	1341	/* The minimum value for ssthresh should be 2 MSS */
hexley	0:281d6ff68967	1342	if (pcb->ssthresh < 2*pcb->mss) {
hexley	0:281d6ff68967	1343	LWIP_DEBUGF(TCP_FR_DEBUG,
hexley	0:281d6ff68967	1344	("tcp_receive: The minimum value for ssthresh %"U16_F
hexley	0:281d6ff68967	1345	" should be min 2 mss %"U16_F"...\n",
hexley	0:281d6ff68967	1346	pcb->ssthresh, 2*pcb->mss));
hexley	0:281d6ff68967	1347	pcb->ssthresh = 2*pcb->mss;
hexley	0:281d6ff68967	1348	}
hexley	0:281d6ff68967	1349
hexley	0:281d6ff68967	1350	pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
hexley	0:281d6ff68967	1351	pcb->flags \|= TF_INFR;
hexley	0:281d6ff68967	1352	}
hexley	0:281d6ff68967	1353	}
hexley	0:281d6ff68967	1354
hexley	0:281d6ff68967	1355
hexley	0:281d6ff68967	1356	/**
hexley	0:281d6ff68967	1357	* Send keepalive packets to keep a connection active although
hexley	0:281d6ff68967	1358	* no data is sent over it.
hexley	0:281d6ff68967	1359	*
hexley	0:281d6ff68967	1360	* Called by tcp_slowtmr()
hexley	0:281d6ff68967	1361	*
hexley	0:281d6ff68967	1362	* @param pcb the tcp_pcb for which to send a keepalive packet
hexley	0:281d6ff68967	1363	*/
hexley	0:281d6ff68967	1364	void
hexley	0:281d6ff68967	1365	tcp_keepalive(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	1366	{
hexley	0:281d6ff68967	1367	struct pbuf *p;
hexley	0:281d6ff68967	1368	struct tcp_hdr *tcphdr;
hexley	0:281d6ff68967	1369
hexley	0:281d6ff68967	1370	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
hexley	0:281d6ff68967	1371	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
hexley	0:281d6ff68967	1372	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
hexley	0:281d6ff68967	1373
hexley	0:281d6ff68967	1374	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
hexley	0:281d6ff68967	1375	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
hexley	0:281d6ff68967	1376
hexley	0:281d6ff68967	1377	p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
hexley	0:281d6ff68967	1378	if(p == NULL) {
hexley	0:281d6ff68967	1379	LWIP_DEBUGF(TCP_DEBUG,
hexley	0:281d6ff68967	1380	("tcp_keepalive: could not allocate memory for pbuf\n"));
hexley	0:281d6ff68967	1381	return;
hexley	0:281d6ff68967	1382	}
hexley	0:281d6ff68967	1383	tcphdr = (struct tcp_hdr *)p->payload;
hexley	0:281d6ff68967	1384
hexley	0:281d6ff68967	1385	#if CHECKSUM_GEN_TCP
hexley	0:281d6ff68967	1386	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
hexley	0:281d6ff68967	1387	IP_PROTO_TCP, p->tot_len);
hexley	0:281d6ff68967	1388	#endif
hexley	0:281d6ff68967	1389	TCP_STATS_INC(tcp.xmit);
hexley	0:281d6ff68967	1390
hexley	0:281d6ff68967	1391	/* Send output to IP */
hexley	0:281d6ff68967	1392	#if LWIP_NETIF_HWADDRHINT
hexley	0:281d6ff68967	1393	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
hexley	0:281d6ff68967	1394	&(pcb->addr_hint));
hexley	0:281d6ff68967	1395	#else /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	1396	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
hexley	0:281d6ff68967	1397	#endif /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	1398
hexley	0:281d6ff68967	1399	pbuf_free(p);
hexley	0:281d6ff68967	1400
hexley	0:281d6ff68967	1401	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
hexley	0:281d6ff68967	1402	pcb->snd_nxt - 1, pcb->rcv_nxt));
hexley	0:281d6ff68967	1403	}
hexley	0:281d6ff68967	1404
hexley	0:281d6ff68967	1405
hexley	0:281d6ff68967	1406	/**
hexley	0:281d6ff68967	1407	* Send persist timer zero-window probes to keep a connection active
hexley	0:281d6ff68967	1408	* when a window update is lost.
hexley	0:281d6ff68967	1409	*
hexley	0:281d6ff68967	1410	* Called by tcp_slowtmr()
hexley	0:281d6ff68967	1411	*
hexley	0:281d6ff68967	1412	* @param pcb the tcp_pcb for which to send a zero-window probe packet
hexley	0:281d6ff68967	1413	*/
hexley	0:281d6ff68967	1414	void
hexley	0:281d6ff68967	1415	tcp_zero_window_probe(struct tcp_pcb *pcb)
hexley	0:281d6ff68967	1416	{
hexley	0:281d6ff68967	1417	struct pbuf *p;
hexley	0:281d6ff68967	1418	struct tcp_hdr *tcphdr;
hexley	0:281d6ff68967	1419	struct tcp_seg *seg;
hexley	0:281d6ff68967	1420	u16_t len;
hexley	0:281d6ff68967	1421	u8_t is_fin;
hexley	0:281d6ff68967	1422
hexley	0:281d6ff68967	1423	LWIP_DEBUGF(TCP_DEBUG,
hexley	0:281d6ff68967	1424	("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
hexley	0:281d6ff68967	1425	U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
hexley	0:281d6ff68967	1426	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
hexley	0:281d6ff68967	1427	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
hexley	0:281d6ff68967	1428
hexley	0:281d6ff68967	1429	LWIP_DEBUGF(TCP_DEBUG,
hexley	0:281d6ff68967	1430	("tcp_zero_window_probe: tcp_ticks %"U32_F
hexley	0:281d6ff68967	1431	" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
hexley	0:281d6ff68967	1432	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
hexley	0:281d6ff68967	1433
hexley	0:281d6ff68967	1434	seg = pcb->unacked;
hexley	0:281d6ff68967	1435
hexley	0:281d6ff68967	1436	if(seg == NULL) {
hexley	0:281d6ff68967	1437	seg = pcb->unsent;
hexley	0:281d6ff68967	1438	}
hexley	0:281d6ff68967	1439	if(seg == NULL) {
hexley	0:281d6ff68967	1440	return;
hexley	0:281d6ff68967	1441	}
hexley	0:281d6ff68967	1442
hexley	0:281d6ff68967	1443	is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
hexley	0:281d6ff68967	1444	/* we want to send one seqno: either FIN or data (no options) */
hexley	0:281d6ff68967	1445	len = is_fin ? 0 : 1;
hexley	0:281d6ff68967	1446
hexley	0:281d6ff68967	1447	p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
hexley	0:281d6ff68967	1448	if(p == NULL) {
hexley	0:281d6ff68967	1449	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
hexley	0:281d6ff68967	1450	return;
hexley	0:281d6ff68967	1451	}
hexley	0:281d6ff68967	1452	tcphdr = (struct tcp_hdr *)p->payload;
hexley	0:281d6ff68967	1453
hexley	0:281d6ff68967	1454	if (is_fin) {
hexley	0:281d6ff68967	1455	/* FIN segment, no data */
hexley	0:281d6ff68967	1456	TCPH_FLAGS_SET(tcphdr, TCP_ACK \| TCP_FIN);
hexley	0:281d6ff68967	1457	} else {
hexley	0:281d6ff68967	1458	/* Data segment, copy in one byte from the head of the unacked queue */
hexley	0:281d6ff68967	1459	((char )p->payload + TCP_HLEN) = (char )seg->dataptr;
hexley	0:281d6ff68967	1460	}
hexley	0:281d6ff68967	1461
hexley	0:281d6ff68967	1462	#if CHECKSUM_GEN_TCP
hexley	0:281d6ff68967	1463	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
hexley	0:281d6ff68967	1464	IP_PROTO_TCP, p->tot_len);
hexley	0:281d6ff68967	1465	#endif
hexley	0:281d6ff68967	1466	TCP_STATS_INC(tcp.xmit);
hexley	0:281d6ff68967	1467
hexley	0:281d6ff68967	1468	/* Send output to IP */
hexley	0:281d6ff68967	1469	#if LWIP_NETIF_HWADDRHINT
hexley	0:281d6ff68967	1470	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
hexley	0:281d6ff68967	1471	&(pcb->addr_hint));
hexley	0:281d6ff68967	1472	#else /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	1473	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
hexley	0:281d6ff68967	1474	#endif /* LWIP_NETIF_HWADDRHINT*/
hexley	0:281d6ff68967	1475
hexley	0:281d6ff68967	1476	pbuf_free(p);
hexley	0:281d6ff68967	1477
hexley	0:281d6ff68967	1478	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
hexley	0:281d6ff68967	1479	" ackno %"U32_F".\n",
hexley	0:281d6ff68967	1480	pcb->snd_nxt - 1, pcb->rcv_nxt));
hexley	0:281d6ff68967	1481	}
hexley	0:281d6ff68967	1482	#endif /* LWIP_TCP */

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Type:	Library
Created:	19 Nov 2010
Imports:	44
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

lwip/core/tcp_out.c@0:281d6ff68967, 2010-11-19 (annotated)

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