Bonjour - modded version Dirk-Willem van Gulik's Bonjour/Ze…

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modded version Dirk-Willem van Gulik's Bonjour/Zerconf library http://mbed.org/users/dirkx/code/Bonjour/

Fork of Bonjour by Dirk-Willem van Gulik (NXP/mbed)

lwip/core/tcp_out.cpp@8:275256b5d807, 2014-10-16 (annotated)

Committer:: casiotone401
Date:: Thu Oct 16 14:13:21 2014 +0000
Revision:: 8:275256b5d807
Parent:: 7:105191e07767

minor change

Who changed what in which revision?

User	Revision	Line number	New contents of line
dirkx	0:355018f44c9f	1	/**
dirkx	0:355018f44c9f	2	* @file
dirkx	0:355018f44c9f	3	* Transmission Control Protocol, outgoing traffic
dirkx	0:355018f44c9f	4	*
dirkx	0:355018f44c9f	5	* The output functions of TCP.
dirkx	0:355018f44c9f	6	*
dirkx	0:355018f44c9f	7	*/
dirkx	0:355018f44c9f	8
dirkx	0:355018f44c9f	9	/*
dirkx	0:355018f44c9f	10	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
dirkx	0:355018f44c9f	11	* All rights reserved.
dirkx	0:355018f44c9f	12	*
dirkx	0:355018f44c9f	13	* Redistribution and use in source and binary forms, with or without modification,
dirkx	0:355018f44c9f	14	* are permitted provided that the following conditions are met:
dirkx	0:355018f44c9f	15	*
dirkx	0:355018f44c9f	16	* 1. Redistributions of source code must retain the above copyright notice,
dirkx	0:355018f44c9f	17	* this list of conditions and the following disclaimer.
dirkx	0:355018f44c9f	18	* 2. Redistributions in binary form must reproduce the above copyright notice,
dirkx	0:355018f44c9f	19	* this list of conditions and the following disclaimer in the documentation
dirkx	0:355018f44c9f	20	* and/or other materials provided with the distribution.
dirkx	0:355018f44c9f	21	* 3. The name of the author may not be used to endorse or promote products
dirkx	0:355018f44c9f	22	* derived from this software without specific prior written permission.
dirkx	0:355018f44c9f	23	*
dirkx	0:355018f44c9f	24	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
dirkx	0:355018f44c9f	25	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
dirkx	0:355018f44c9f	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
dirkx	0:355018f44c9f	27	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
dirkx	0:355018f44c9f	28	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
dirkx	0:355018f44c9f	29	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
dirkx	0:355018f44c9f	30	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
dirkx	0:355018f44c9f	31	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
dirkx	0:355018f44c9f	32	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
dirkx	0:355018f44c9f	33	* OF SUCH DAMAGE.
dirkx	0:355018f44c9f	34	*
dirkx	0:355018f44c9f	35	* This file is part of the lwIP TCP/IP stack.
dirkx	0:355018f44c9f	36	*
dirkx	0:355018f44c9f	37	* Author: Adam Dunkels <adam@sics.se>
dirkx	0:355018f44c9f	38	*
dirkx	0:355018f44c9f	39	*/
dirkx	0:355018f44c9f	40
dirkx	0:355018f44c9f	41	#include "lwip/opt.h"
dirkx	0:355018f44c9f	42
dirkx	0:355018f44c9f	43	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
dirkx	0:355018f44c9f	44
dirkx	0:355018f44c9f	45	#include "lwip/tcp_impl.h"
dirkx	0:355018f44c9f	46	#include "lwip/def.h"
dirkx	0:355018f44c9f	47	#include "lwip/mem.h"
dirkx	0:355018f44c9f	48	#include "lwip/memp.h"
dirkx	0:355018f44c9f	49	#include "lwip/sys.h"
dirkx	0:355018f44c9f	50	#include "lwip/ip_addr.h"
dirkx	0:355018f44c9f	51	#include "lwip/netif.h"
dirkx	0:355018f44c9f	52	#include "lwip/inet_chksum.h"
dirkx	0:355018f44c9f	53	#include "lwip/stats.h"
dirkx	0:355018f44c9f	54	#include "lwip/snmp.h"
dirkx	0:355018f44c9f	55
dirkx	0:355018f44c9f	56	#include <string.h>
dirkx	0:355018f44c9f	57
dirkx	0:355018f44c9f	58	/* Define some copy-macros for checksum-on-copy so that the code looks
dirkx	0:355018f44c9f	59	nicer by preventing too many ifdef's. */
dirkx	0:355018f44c9f	60	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	61	#define TCP_DATA_COPY(dst, src, len, seg) do { \
dirkx	0:355018f44c9f	62	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
dirkx	0:355018f44c9f	63	len, &seg->chksum, &seg->chksum_swapped); \
dirkx	0:355018f44c9f	64	seg->flags \|= TF_SEG_DATA_CHECKSUMMED; } while(0)
dirkx	0:355018f44c9f	65	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
dirkx	0:355018f44c9f	66	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
dirkx	0:355018f44c9f	67	#else /* TCP_CHECKSUM_ON_COPY*/
dirkx	0:355018f44c9f	68	#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
dirkx	0:355018f44c9f	69	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
dirkx	0:355018f44c9f	70	#endif /* TCP_CHECKSUM_ON_COPY*/
dirkx	0:355018f44c9f	71
dirkx	0:355018f44c9f	72	/** Define this to 1 for an extra check that the output checksum is valid
dirkx	0:355018f44c9f	73	* (usefule when the checksum is generated by the application, not the stack) */
dirkx	0:355018f44c9f	74	#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
dirkx	0:355018f44c9f	75	#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
dirkx	0:355018f44c9f	76	#endif
dirkx	0:355018f44c9f	77
dirkx	0:355018f44c9f	78	/* Forward declarations.*/
dirkx	0:355018f44c9f	79	static void tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb);
dirkx	0:355018f44c9f	80
dirkx	0:355018f44c9f	81	/** Allocate a pbuf and create a tcphdr at p->payload, used for output
dirkx	0:355018f44c9f	82	* functions other than the default tcp_output -> tcp_output_segment
dirkx	0:355018f44c9f	83	* (e.g. tcp_send_empty_ack, etc.)
dirkx	0:355018f44c9f	84	*
dirkx	0:355018f44c9f	85	* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
dirkx	0:355018f44c9f	86	* @param optlen length of header-options
dirkx	0:355018f44c9f	87	* @param datalen length of tcp data to reserve in pbuf
dirkx	0:355018f44c9f	88	* @param seqno_be seqno in network byte order (big-endian)
dirkx	0:355018f44c9f	89	* @return pbuf with p->payload being the tcp_hdr
dirkx	0:355018f44c9f	90	*/
dirkx	0:355018f44c9f	91	static struct pbuf *
dirkx	0:355018f44c9f	92	tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
dirkx	0:355018f44c9f	93	u32_t seqno_be /* already in network byte order */)
dirkx	0:355018f44c9f	94	{
dirkx	0:355018f44c9f	95	struct tcp_hdr *tcphdr;
dirkx	0:355018f44c9f	96	struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
dirkx	0:355018f44c9f	97	if (p != NULL) {
dirkx	0:355018f44c9f	98	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
dirkx	0:355018f44c9f	99	(p->len >= TCP_HLEN + optlen));
dirkx	0:355018f44c9f	100	tcphdr = (struct tcp_hdr *)p->payload;
dirkx	0:355018f44c9f	101	tcphdr->src = htons(pcb->local_port);
dirkx	0:355018f44c9f	102	tcphdr->dest = htons(pcb->remote_port);
dirkx	0:355018f44c9f	103	tcphdr->seqno = seqno_be;
dirkx	0:355018f44c9f	104	tcphdr->ackno = htonl(pcb->rcv_nxt);
dirkx	0:355018f44c9f	105	TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
dirkx	0:355018f44c9f	106	tcphdr->wnd = htons(pcb->rcv_ann_wnd);
dirkx	0:355018f44c9f	107	tcphdr->chksum = 0;
dirkx	0:355018f44c9f	108	tcphdr->urgp = 0;
dirkx	0:355018f44c9f	109
dirkx	0:355018f44c9f	110	/* If we're sending a packet, update the announced right window edge */
dirkx	0:355018f44c9f	111	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
dirkx	0:355018f44c9f	112	}
dirkx	0:355018f44c9f	113	return p;
dirkx	0:355018f44c9f	114	}
dirkx	0:355018f44c9f	115
dirkx	0:355018f44c9f	116	/**
dirkx	0:355018f44c9f	117	* Called by tcp_close() to send a segment including FIN flag but not data.
dirkx	0:355018f44c9f	118	*
dirkx	0:355018f44c9f	119	* @param pcb the tcp_pcb over which to send a segment
dirkx	0:355018f44c9f	120	* @return ERR_OK if sent, another err_t otherwise
dirkx	0:355018f44c9f	121	*/
dirkx	0:355018f44c9f	122	err_t
dirkx	0:355018f44c9f	123	tcp_send_fin(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	124	{
dirkx	0:355018f44c9f	125	/* first, try to add the fin to the last unsent segment */
dirkx	0:355018f44c9f	126	if (pcb->unsent != NULL) {
dirkx	0:355018f44c9f	127	struct tcp_seg *last_unsent;
dirkx	0:355018f44c9f	128	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
dirkx	0:355018f44c9f	129	last_unsent = last_unsent->next);
dirkx	0:355018f44c9f	130
dirkx	0:355018f44c9f	131	if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN \| TCP_FIN \| TCP_RST)) == 0) {
dirkx	0:355018f44c9f	132	/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
dirkx	0:355018f44c9f	133	TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
dirkx	0:355018f44c9f	134	return ERR_OK;
dirkx	0:355018f44c9f	135	}
dirkx	0:355018f44c9f	136	}
dirkx	0:355018f44c9f	137	/* no data, no length, flags, copy=1, no optdata */
dirkx	0:355018f44c9f	138	return tcp_enqueue_flags(pcb, TCP_FIN);
dirkx	0:355018f44c9f	139	}
dirkx	0:355018f44c9f	140
dirkx	0:355018f44c9f	141	/**
dirkx	0:355018f44c9f	142	* Create a TCP segment with prefilled header.
dirkx	0:355018f44c9f	143	*
dirkx	0:355018f44c9f	144	* Called by tcp_write and tcp_enqueue_flags.
dirkx	0:355018f44c9f	145	*
dirkx	0:355018f44c9f	146	* @param pcb Protocol control block for the TCP connection.
dirkx	0:355018f44c9f	147	* @param p pbuf that is used to hold the TCP header.
dirkx	0:355018f44c9f	148	* @param flags TCP flags for header.
dirkx	0:355018f44c9f	149	* @param seqno TCP sequence number of this packet
dirkx	0:355018f44c9f	150	* @param optflags options to include in TCP header
dirkx	0:355018f44c9f	151	* @return a new tcp_seg pointing to p, or NULL.
dirkx	0:355018f44c9f	152	* The TCP header is filled in except ackno and wnd.
dirkx	0:355018f44c9f	153	* p is freed on failure.
dirkx	0:355018f44c9f	154	*/
dirkx	0:355018f44c9f	155	static struct tcp_seg *
dirkx	0:355018f44c9f	156	tcp_create_segment(struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
dirkx	0:355018f44c9f	157	{
dirkx	0:355018f44c9f	158	struct tcp_seg *seg;
dirkx	0:355018f44c9f	159	u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
dirkx	0:355018f44c9f	160
dirkx	0:355018f44c9f	161	if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
dirkx	0:355018f44c9f	162	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no memory.\n"));
dirkx	0:355018f44c9f	163	pbuf_free(p);
dirkx	0:355018f44c9f	164	return NULL;
dirkx	0:355018f44c9f	165	}
dirkx	0:355018f44c9f	166	seg->flags = optflags;
dirkx	0:355018f44c9f	167	seg->next = NULL;
dirkx	0:355018f44c9f	168	seg->p = p;
dirkx	0:355018f44c9f	169	seg->dataptr = p->payload;
dirkx	0:355018f44c9f	170	seg->len = p->tot_len - optlen;
dirkx	0:355018f44c9f	171	#if TCP_OVERSIZE_DBGCHECK
dirkx	0:355018f44c9f	172	seg->oversize_left = 0;
dirkx	0:355018f44c9f	173	#endif /* TCP_OVERSIZE_DBGCHECK */
dirkx	0:355018f44c9f	174	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	175	seg->chksum = 0;
dirkx	0:355018f44c9f	176	seg->chksum_swapped = 0;
dirkx	0:355018f44c9f	177	/* check optflags */
dirkx	0:355018f44c9f	178	LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
dirkx	0:355018f44c9f	179	(optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
dirkx	0:355018f44c9f	180	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	181
dirkx	0:355018f44c9f	182	/* build TCP header */
dirkx	0:355018f44c9f	183	if (pbuf_header(p, TCP_HLEN)) {
dirkx	0:355018f44c9f	184	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
dirkx	0:355018f44c9f	185	TCP_STATS_INC(tcp.err);
dirkx	0:355018f44c9f	186	tcp_seg_free(seg);
dirkx	0:355018f44c9f	187	return NULL;
dirkx	0:355018f44c9f	188	}
dirkx	0:355018f44c9f	189	seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
dirkx	0:355018f44c9f	190	seg->tcphdr->src = htons(pcb->local_port);
dirkx	0:355018f44c9f	191	seg->tcphdr->dest = htons(pcb->remote_port);
dirkx	0:355018f44c9f	192	seg->tcphdr->seqno = htonl(seqno);
dirkx	0:355018f44c9f	193	/* ackno is set in tcp_output */
dirkx	0:355018f44c9f	194	TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
dirkx	0:355018f44c9f	195	/* wnd and chksum are set in tcp_output */
dirkx	0:355018f44c9f	196	seg->tcphdr->urgp = 0;
dirkx	0:355018f44c9f	197	return seg;
dirkx	0:355018f44c9f	198	}
dirkx	0:355018f44c9f	199
dirkx	0:355018f44c9f	200	/**
dirkx	0:355018f44c9f	201	* Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
dirkx	0:355018f44c9f	202	*
dirkx	0:355018f44c9f	203	* This function is like pbuf_alloc(layer, length, PBUF_RAM) except
dirkx	0:355018f44c9f	204	* there may be extra bytes available at the end.
dirkx	0:355018f44c9f	205	*
dirkx	0:355018f44c9f	206	* @param layer flag to define header size.
dirkx	0:355018f44c9f	207	* @param length size of the pbuf's payload.
dirkx	0:355018f44c9f	208	* @param max_length maximum usable size of payload+oversize.
dirkx	0:355018f44c9f	209	* @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
dirkx	0:355018f44c9f	210	* @param pcb The TCP connection that willo enqueue the pbuf.
dirkx	0:355018f44c9f	211	* @param apiflags API flags given to tcp_write.
dirkx	0:355018f44c9f	212	* @param first_seg true when this pbuf will be used in the first enqueued segment.
dirkx	0:355018f44c9f	213	* @param
dirkx	0:355018f44c9f	214	*/
dirkx	0:355018f44c9f	215	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	216	static struct pbuf *
dirkx	0:355018f44c9f	217	tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
dirkx	0:355018f44c9f	218	u16_t oversize, struct tcp_pcb pcb, u8_t apiflags,
dirkx	0:355018f44c9f	219	u8_t first_seg)
dirkx	0:355018f44c9f	220	{
dirkx	0:355018f44c9f	221	struct pbuf *p;
dirkx	0:355018f44c9f	222	u16_t alloc = length;
dirkx	0:355018f44c9f	223
dirkx	0:355018f44c9f	224	if (length < max_length) {
dirkx	0:355018f44c9f	225	/* Should we allocate an oversized pbuf, or just the minimum
dirkx	0:355018f44c9f	226	* length required? If tcp_write is going to be called again
dirkx	0:355018f44c9f	227	* before this segment is transmitted, we want the oversized
dirkx	0:355018f44c9f	228	* buffer. If the segment will be transmitted immediately, we can
dirkx	0:355018f44c9f	229	* save memory by allocating only length. We use a simple
dirkx	0:355018f44c9f	230	* heuristic based on the following information:
dirkx	0:355018f44c9f	231	*
dirkx	0:355018f44c9f	232	* Did the user set TCP_WRITE_FLAG_MORE?
dirkx	0:355018f44c9f	233	*
dirkx	0:355018f44c9f	234	* Will the Nagle algorithm defer transmission of this segment?
dirkx	0:355018f44c9f	235	*/
dirkx	0:355018f44c9f	236	if ((apiflags & TCP_WRITE_FLAG_MORE) \|\|
dirkx	0:355018f44c9f	237	(!(pcb->flags & TF_NODELAY) &&
dirkx	0:355018f44c9f	238	(!first_seg \|\|
dirkx	0:355018f44c9f	239	pcb->unsent != NULL \|\|
dirkx	0:355018f44c9f	240	pcb->unacked != NULL))) {
dirkx	0:355018f44c9f	241	alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
dirkx	0:355018f44c9f	242	}
dirkx	0:355018f44c9f	243	}
dirkx	0:355018f44c9f	244	p = pbuf_alloc(layer, alloc, PBUF_RAM);
dirkx	0:355018f44c9f	245	if (p == NULL) {
dirkx	0:355018f44c9f	246	return NULL;
dirkx	0:355018f44c9f	247	}
dirkx	0:355018f44c9f	248	LWIP_ASSERT("need unchained pbuf", p->next == NULL);
dirkx	0:355018f44c9f	249	*oversize = p->len - length;
dirkx	0:355018f44c9f	250	/* trim p->len to the currently used size */
dirkx	0:355018f44c9f	251	p->len = p->tot_len = length;
dirkx	0:355018f44c9f	252	return p;
dirkx	0:355018f44c9f	253	}
dirkx	0:355018f44c9f	254	#else /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	255	#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
dirkx	0:355018f44c9f	256	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	257
dirkx	0:355018f44c9f	258	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	259	/** Add a checksum of newly added data to the segment */
dirkx	0:355018f44c9f	260	static void
dirkx	0:355018f44c9f	261	tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
dirkx	0:355018f44c9f	262	u8_t *seg_chksum_swapped)
dirkx	0:355018f44c9f	263	{
dirkx	0:355018f44c9f	264	u32_t helper;
dirkx	0:355018f44c9f	265	/* add chksum to old chksum and fold to u16_t */
dirkx	0:355018f44c9f	266	helper = chksum + *seg_chksum;
dirkx	0:355018f44c9f	267	chksum = FOLD_U32T(helper);
dirkx	0:355018f44c9f	268	if ((len & 1) != 0) {
dirkx	0:355018f44c9f	269	seg_chksum_swapped = 1 - seg_chksum_swapped;
dirkx	0:355018f44c9f	270	chksum = SWAP_BYTES_IN_WORD(chksum);
dirkx	0:355018f44c9f	271	}
dirkx	0:355018f44c9f	272	*seg_chksum = chksum;
dirkx	0:355018f44c9f	273	}
dirkx	0:355018f44c9f	274	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	275
dirkx	0:355018f44c9f	276	/**
dirkx	0:355018f44c9f	277	* Write data for sending (but does not send it immediately).
dirkx	0:355018f44c9f	278	*
dirkx	0:355018f44c9f	279	* It waits in the expectation of more data being sent soon (as
dirkx	0:355018f44c9f	280	* it can send them more efficiently by combining them together).
dirkx	0:355018f44c9f	281	* To prompt the system to send data now, call tcp_output() after
dirkx	0:355018f44c9f	282	* calling tcp_write().
dirkx	0:355018f44c9f	283	*
dirkx	0:355018f44c9f	284	* @param pcb Protocol control block for the TCP connection to enqueue data for.
dirkx	0:355018f44c9f	285	* @param arg Pointer to the data to be enqueued for sending.
dirkx	0:355018f44c9f	286	* @param len Data length in bytes
dirkx	0:355018f44c9f	287	* @param apiflags combination of following flags :
dirkx	0:355018f44c9f	288	* - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
dirkx	0:355018f44c9f	289	* - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
dirkx	0:355018f44c9f	290	* @return ERR_OK if enqueued, another err_t on error
dirkx	0:355018f44c9f	291	*/
dirkx	0:355018f44c9f	292	err_t
dirkx	0:355018f44c9f	293	tcp_write(struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
dirkx	0:355018f44c9f	294	{
dirkx	0:355018f44c9f	295	struct pbuf *concat_p = NULL;
dirkx	0:355018f44c9f	296	struct tcp_seg last_unsent = NULL, seg = NULL, prev_seg = NULL, queue = NULL;
dirkx	0:355018f44c9f	297	u16_t pos = 0; /* position in 'arg' data */
dirkx	0:355018f44c9f	298	u16_t queuelen;
dirkx	0:355018f44c9f	299	u8_t optlen = 0;
dirkx	0:355018f44c9f	300	u8_t optflags = 0;
dirkx	0:355018f44c9f	301	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	302	u16_t oversize = 0;
dirkx	0:355018f44c9f	303	u16_t oversize_used = 0;
dirkx	0:355018f44c9f	304	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	305	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	306	u16_t concat_chksum = 0;
dirkx	0:355018f44c9f	307	u8_t concat_chksum_swapped = 0;
dirkx	0:355018f44c9f	308	u16_t concat_chksummed = 0;
dirkx	0:355018f44c9f	309	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	310
dirkx	0:355018f44c9f	311	#if LWIP_NETIF_TX_SINGLE_PBUF
dirkx	0:355018f44c9f	312	/* Always copy to try to create single pbufs for TX */
dirkx	0:355018f44c9f	313	apiflags \|= TCP_WRITE_FLAG_COPY;
dirkx	0:355018f44c9f	314	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
dirkx	0:355018f44c9f	315
dirkx	0:355018f44c9f	316	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
dirkx	0:355018f44c9f	317	(void *)pcb, arg, len, (u16_t)apiflags));
dirkx	0:355018f44c9f	318	/* connection is in invalid state for data transmission? */
dirkx	0:355018f44c9f	319	if ((pcb->state != ESTABLISHED) &&
dirkx	0:355018f44c9f	320	(pcb->state != CLOSE_WAIT) &&
dirkx	0:355018f44c9f	321	(pcb->state != SYN_SENT) &&
dirkx	0:355018f44c9f	322	(pcb->state != SYN_RCVD)) {
dirkx	0:355018f44c9f	323	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_STATE \| LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
dirkx	0:355018f44c9f	324	return ERR_CONN;
dirkx	0:355018f44c9f	325	} else if (len == 0) {
dirkx	0:355018f44c9f	326	return ERR_OK;
dirkx	0:355018f44c9f	327	}
dirkx	0:355018f44c9f	328
dirkx	0:355018f44c9f	329	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, arg=%p, len=%"U16_F", apiflags=%"U16_F")\n",
dirkx	0:355018f44c9f	330	(void *)pcb, arg, len, (u16_t)apiflags));
dirkx	0:355018f44c9f	331	LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
dirkx	0:355018f44c9f	332	arg != NULL, return ERR_ARG;);
dirkx	0:355018f44c9f	333
dirkx	0:355018f44c9f	334	/* fail on too much data */
dirkx	0:355018f44c9f	335	if (len > pcb->snd_buf) {
dirkx	0:355018f44c9f	336	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
dirkx	0:355018f44c9f	337	len, pcb->snd_buf));
dirkx	0:355018f44c9f	338	pcb->flags \|= TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	339	return ERR_MEM;
dirkx	0:355018f44c9f	340	}
dirkx	0:355018f44c9f	341
dirkx	0:355018f44c9f	342	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
dirkx	0:355018f44c9f	343
dirkx	0:355018f44c9f	344	/* If total number of pbufs on the unsent/unacked queues exceeds the
dirkx	0:355018f44c9f	345	* configured maximum, return an error */
dirkx	0:355018f44c9f	346	queuelen = pcb->snd_queuelen;
dirkx	0:355018f44c9f	347	/* check for configured max queuelen and possible overflow */
dirkx	0:355018f44c9f	348	if ((queuelen >= TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
dirkx	0:355018f44c9f	349	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
dirkx	0:355018f44c9f	350	queuelen, TCP_SND_QUEUELEN));
dirkx	0:355018f44c9f	351	TCP_STATS_INC(tcp.memerr);
dirkx	0:355018f44c9f	352	pcb->flags \|= TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	353	return ERR_MEM;
dirkx	0:355018f44c9f	354	}
dirkx	0:355018f44c9f	355	if (queuelen != 0) {
dirkx	0:355018f44c9f	356	LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
dirkx	0:355018f44c9f	357	pcb->unacked != NULL \|\| pcb->unsent != NULL);
dirkx	0:355018f44c9f	358	} else {
dirkx	0:355018f44c9f	359	LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
dirkx	0:355018f44c9f	360	pcb->unacked == NULL && pcb->unsent == NULL);
dirkx	0:355018f44c9f	361	}
dirkx	0:355018f44c9f	362
dirkx	0:355018f44c9f	363	#if LWIP_TCP_TIMESTAMPS
dirkx	0:355018f44c9f	364	if ((pcb->flags & TF_TIMESTAMP)) {
dirkx	0:355018f44c9f	365	optflags = TF_SEG_OPTS_TS;
dirkx	0:355018f44c9f	366	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
dirkx	0:355018f44c9f	367	}
dirkx	0:355018f44c9f	368	#endif /* LWIP_TCP_TIMESTAMPS */
dirkx	0:355018f44c9f	369
dirkx	0:355018f44c9f	370
dirkx	0:355018f44c9f	371	/*
dirkx	0:355018f44c9f	372	* TCP segmentation is done in three phases with increasing complexity:
dirkx	0:355018f44c9f	373	*
dirkx	0:355018f44c9f	374	* 1. Copy data directly into an oversized pbuf.
dirkx	0:355018f44c9f	375	* 2. Chain a new pbuf to the end of pcb->unsent.
dirkx	0:355018f44c9f	376	* 3. Create new segments.
dirkx	0:355018f44c9f	377	*
dirkx	0:355018f44c9f	378	* We may run out of memory at any point. In that case we must
dirkx	0:355018f44c9f	379	* return ERR_MEM and not change anything in pcb. Therefore, all
dirkx	0:355018f44c9f	380	* changes are recorded in local variables and committed at the end
dirkx	0:355018f44c9f	381	* of the function. Some pcb fields are maintained in local copies:
dirkx	0:355018f44c9f	382	*
dirkx	0:355018f44c9f	383	* queuelen = pcb->snd_queuelen
dirkx	0:355018f44c9f	384	* oversize = pcb->unsent_oversize
dirkx	0:355018f44c9f	385	*
dirkx	0:355018f44c9f	386	* These variables are set consistently by the phases:
dirkx	0:355018f44c9f	387	*
dirkx	0:355018f44c9f	388	* seg points to the last segment tampered with.
dirkx	0:355018f44c9f	389	*
dirkx	0:355018f44c9f	390	* pos records progress as data is segmented.
dirkx	0:355018f44c9f	391	*/
dirkx	0:355018f44c9f	392
dirkx	0:355018f44c9f	393	/* Find the tail of the unsent queue. */
dirkx	0:355018f44c9f	394	if (pcb->unsent != NULL) {
dirkx	0:355018f44c9f	395	u16_t space;
dirkx	0:355018f44c9f	396	u16_t unsent_optlen;
dirkx	0:355018f44c9f	397
dirkx	0:355018f44c9f	398	/* @todo: this could be sped up by keeping last_unsent in the pcb */
dirkx	0:355018f44c9f	399	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
dirkx	0:355018f44c9f	400	last_unsent = last_unsent->next);
dirkx	0:355018f44c9f	401
dirkx	0:355018f44c9f	402	/* Usable space at the end of the last unsent segment */
dirkx	0:355018f44c9f	403	unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
dirkx	0:355018f44c9f	404	space = pcb->mss - (last_unsent->len + unsent_optlen);
dirkx	0:355018f44c9f	405
dirkx	0:355018f44c9f	406	/*
dirkx	0:355018f44c9f	407	* Phase 1: Copy data directly into an oversized pbuf.
dirkx	0:355018f44c9f	408	*
dirkx	0:355018f44c9f	409	* The number of bytes copied is recorded in the oversize_used
dirkx	0:355018f44c9f	410	* variable. The actual copying is done at the bottom of the
dirkx	0:355018f44c9f	411	* function.
dirkx	0:355018f44c9f	412	*/
dirkx	0:355018f44c9f	413	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	414	#if TCP_OVERSIZE_DBGCHECK
dirkx	0:355018f44c9f	415	/* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
dirkx	0:355018f44c9f	416	LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
dirkx	0:355018f44c9f	417	pcb->unsent_oversize == last_unsent->oversize_left);
dirkx	0:355018f44c9f	418	#endif /* TCP_OVERSIZE_DBGCHECK */
dirkx	0:355018f44c9f	419	oversize = pcb->unsent_oversize;
dirkx	0:355018f44c9f	420	if (oversize > 0) {
dirkx	0:355018f44c9f	421	LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
dirkx	0:355018f44c9f	422	seg = last_unsent;
dirkx	0:355018f44c9f	423	oversize_used = oversize < len ? oversize : len;
dirkx	0:355018f44c9f	424	pos += oversize_used;
dirkx	0:355018f44c9f	425	oversize -= oversize_used;
dirkx	0:355018f44c9f	426	space -= oversize_used;
dirkx	0:355018f44c9f	427	}
dirkx	0:355018f44c9f	428	/* now we are either finished or oversize is zero */
dirkx	0:355018f44c9f	429	LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) \|\| (pos == len));
dirkx	0:355018f44c9f	430	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	431
dirkx	0:355018f44c9f	432	/*
dirkx	0:355018f44c9f	433	* Phase 2: Chain a new pbuf to the end of pcb->unsent.
dirkx	0:355018f44c9f	434	*
dirkx	0:355018f44c9f	435	* We don't extend segments containing SYN/FIN flags or options
dirkx	0:355018f44c9f	436	* (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
dirkx	0:355018f44c9f	437	* the end.
dirkx	0:355018f44c9f	438	*/
dirkx	0:355018f44c9f	439	if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
dirkx	0:355018f44c9f	440	u16_t seglen = space < len - pos ? space : len - pos;
dirkx	0:355018f44c9f	441	seg = last_unsent;
dirkx	0:355018f44c9f	442
dirkx	0:355018f44c9f	443	/* Create a pbuf with a copy or reference to seglen bytes. We
dirkx	0:355018f44c9f	444	* can use PBUF_RAW here since the data appears in the middle of
dirkx	0:355018f44c9f	445	* a segment. A header will never be prepended. */
dirkx	0:355018f44c9f	446	if (apiflags & TCP_WRITE_FLAG_COPY) {
dirkx	0:355018f44c9f	447	/* Data is copied */
dirkx	0:355018f44c9f	448	if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
dirkx	0:355018f44c9f	449	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
dirkx	0:355018f44c9f	450	("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
dirkx	0:355018f44c9f	451	seglen));
dirkx	0:355018f44c9f	452	goto memerr;
dirkx	0:355018f44c9f	453	}
dirkx	0:355018f44c9f	454	#if TCP_OVERSIZE_DBGCHECK
dirkx	0:355018f44c9f	455	last_unsent->oversize_left = oversize;
dirkx	0:355018f44c9f	456	#endif /* TCP_OVERSIZE_DBGCHECK */
dirkx	0:355018f44c9f	457	TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
dirkx	0:355018f44c9f	458	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	459	concat_chksummed += seglen;
dirkx	0:355018f44c9f	460	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	461	} else {
dirkx	0:355018f44c9f	462	/* Data is not copied */
dirkx	0:355018f44c9f	463	if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
dirkx	0:355018f44c9f	464	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
dirkx	0:355018f44c9f	465	("tcp_write: could not allocate memory for zero-copy pbuf\n"));
dirkx	0:355018f44c9f	466	goto memerr;
dirkx	0:355018f44c9f	467	}
dirkx	0:355018f44c9f	468	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	469	/* calculate the checksum of nocopy-data */
dirkx	0:355018f44c9f	470	tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
dirkx	0:355018f44c9f	471	&concat_chksum, &concat_chksum_swapped);
dirkx	0:355018f44c9f	472	concat_chksummed += seglen;
dirkx	0:355018f44c9f	473	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	474	/* reference the non-volatile payload data */
dirkx	0:355018f44c9f	475	concat_p->payload = (u8_t*)arg + pos;
dirkx	0:355018f44c9f	476	}
dirkx	0:355018f44c9f	477
dirkx	0:355018f44c9f	478	pos += seglen;
dirkx	0:355018f44c9f	479	queuelen += pbuf_clen(concat_p);
dirkx	0:355018f44c9f	480	}
dirkx	0:355018f44c9f	481	} else {
dirkx	0:355018f44c9f	482	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	483	LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
dirkx	0:355018f44c9f	484	pcb->unsent_oversize == 0);
dirkx	0:355018f44c9f	485	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	486	}
dirkx	0:355018f44c9f	487
dirkx	0:355018f44c9f	488	/*
dirkx	0:355018f44c9f	489	* Phase 3: Create new segments.
dirkx	0:355018f44c9f	490	*
dirkx	0:355018f44c9f	491	* The new segments are chained together in the local 'queue'
dirkx	0:355018f44c9f	492	* variable, ready to be appended to pcb->unsent.
dirkx	0:355018f44c9f	493	*/
dirkx	0:355018f44c9f	494	while (pos < len) {
dirkx	0:355018f44c9f	495	struct pbuf *p;
dirkx	0:355018f44c9f	496	u16_t left = len - pos;
dirkx	0:355018f44c9f	497	u16_t max_len = pcb->mss - optlen;
dirkx	0:355018f44c9f	498	u16_t seglen = left > max_len ? max_len : left;
dirkx	0:355018f44c9f	499	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	500	u16_t chksum = 0;
dirkx	0:355018f44c9f	501	u8_t chksum_swapped = 0;
dirkx	0:355018f44c9f	502	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	503
dirkx	0:355018f44c9f	504	if (apiflags & TCP_WRITE_FLAG_COPY) {
dirkx	0:355018f44c9f	505	/* If copy is set, memory should be allocated and data copied
dirkx	0:355018f44c9f	506	* into pbuf */
dirkx	0:355018f44c9f	507	if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, pcb->mss, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
dirkx	0:355018f44c9f	508	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
dirkx	0:355018f44c9f	509	goto memerr;
dirkx	0:355018f44c9f	510	}
dirkx	0:355018f44c9f	511	LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
dirkx	0:355018f44c9f	512	(p->len >= seglen));
dirkx	0:355018f44c9f	513	TCP_DATA_COPY2((char )p->payload + optlen, (u8_t)arg + pos, seglen, &chksum, &chksum_swapped);
dirkx	0:355018f44c9f	514	} else {
dirkx	0:355018f44c9f	515	/* Copy is not set: First allocate a pbuf for holding the data.
dirkx	0:355018f44c9f	516	* Since the referenced data is available at least until it is
dirkx	0:355018f44c9f	517	* sent out on the link (as it has to be ACKed by the remote
dirkx	0:355018f44c9f	518	* party) we can safely use PBUF_ROM instead of PBUF_REF here.
dirkx	0:355018f44c9f	519	*/
dirkx	0:355018f44c9f	520	struct pbuf *p2;
dirkx	0:355018f44c9f	521	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	522	LWIP_ASSERT("oversize == 0", oversize == 0);
dirkx	0:355018f44c9f	523	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	524	if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
dirkx	0:355018f44c9f	525	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
dirkx	0:355018f44c9f	526	goto memerr;
dirkx	0:355018f44c9f	527	}
dirkx	0:355018f44c9f	528	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	529	/* calculate the checksum of nocopy-data */
dirkx	0:355018f44c9f	530	chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
dirkx	0:355018f44c9f	531	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	532	/* reference the non-volatile payload data */
dirkx	0:355018f44c9f	533	p2->payload = (u8_t*)arg + pos;
dirkx	0:355018f44c9f	534
dirkx	0:355018f44c9f	535	/* Second, allocate a pbuf for the headers. */
dirkx	0:355018f44c9f	536	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
dirkx	0:355018f44c9f	537	/* If allocation fails, we have to deallocate the data pbuf as
dirkx	0:355018f44c9f	538	* well. */
dirkx	0:355018f44c9f	539	pbuf_free(p2);
dirkx	0:355018f44c9f	540	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for header pbuf\n"));
dirkx	0:355018f44c9f	541	goto memerr;
dirkx	0:355018f44c9f	542	}
dirkx	0:355018f44c9f	543	/* Concatenate the headers and data pbufs together. */
dirkx	0:355018f44c9f	544	pbuf_cat(p/header/, p2/data/);
dirkx	0:355018f44c9f	545	}
dirkx	0:355018f44c9f	546
dirkx	0:355018f44c9f	547	queuelen += pbuf_clen(p);
dirkx	0:355018f44c9f	548
dirkx	0:355018f44c9f	549	/* Now that there are more segments queued, we check again if the
dirkx	0:355018f44c9f	550	* length of the queue exceeds the configured maximum or
dirkx	0:355018f44c9f	551	* overflows. */
dirkx	0:355018f44c9f	552	if ((queuelen > TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
dirkx	0:355018f44c9f	553	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
dirkx	0:355018f44c9f	554	pbuf_free(p);
dirkx	0:355018f44c9f	555	goto memerr;
dirkx	0:355018f44c9f	556	}
dirkx	0:355018f44c9f	557
dirkx	0:355018f44c9f	558	if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
dirkx	0:355018f44c9f	559	goto memerr;
dirkx	0:355018f44c9f	560	}
dirkx	0:355018f44c9f	561	#if TCP_OVERSIZE_DBGCHECK
dirkx	0:355018f44c9f	562	seg->oversize_left = oversize;
dirkx	0:355018f44c9f	563	#endif /* TCP_OVERSIZE_DBGCHECK */
dirkx	0:355018f44c9f	564	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	565	seg->chksum = chksum;
dirkx	0:355018f44c9f	566	seg->chksum_swapped = chksum_swapped;
dirkx	0:355018f44c9f	567	seg->flags \|= TF_SEG_DATA_CHECKSUMMED;
dirkx	0:355018f44c9f	568	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	569	/* Fix dataptr for the nocopy case */
dirkx	0:355018f44c9f	570	if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
dirkx	0:355018f44c9f	571	seg->dataptr = (u8_t*)arg + pos;
dirkx	0:355018f44c9f	572	}
dirkx	0:355018f44c9f	573
dirkx	0:355018f44c9f	574	/* first segment of to-be-queued data? */
dirkx	0:355018f44c9f	575	if (queue == NULL) {
dirkx	0:355018f44c9f	576	queue = seg;
dirkx	0:355018f44c9f	577	} else {
dirkx	0:355018f44c9f	578	/* Attach the segment to the end of the queued segments */
dirkx	0:355018f44c9f	579	LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
dirkx	0:355018f44c9f	580	prev_seg->next = seg;
dirkx	0:355018f44c9f	581	}
dirkx	0:355018f44c9f	582	/* remember last segment of to-be-queued data for next iteration */
dirkx	0:355018f44c9f	583	prev_seg = seg;
dirkx	0:355018f44c9f	584
dirkx	0:355018f44c9f	585	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
dirkx	0:355018f44c9f	586	ntohl(seg->tcphdr->seqno),
dirkx	0:355018f44c9f	587	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
dirkx	0:355018f44c9f	588
dirkx	0:355018f44c9f	589	pos += seglen;
dirkx	0:355018f44c9f	590	}
dirkx	0:355018f44c9f	591
dirkx	0:355018f44c9f	592	/*
dirkx	0:355018f44c9f	593	* All three segmentation phases were successful. We can commit the
dirkx	0:355018f44c9f	594	* transaction.
dirkx	0:355018f44c9f	595	*/
dirkx	0:355018f44c9f	596
dirkx	0:355018f44c9f	597	/*
dirkx	0:355018f44c9f	598	* Phase 1: If data has been added to the preallocated tail of
dirkx	0:355018f44c9f	599	* last_unsent, we update the length fields of the pbuf chain.
dirkx	0:355018f44c9f	600	*/
dirkx	0:355018f44c9f	601	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	602	if (oversize_used > 0) {
dirkx	0:355018f44c9f	603	struct pbuf *p;
dirkx	0:355018f44c9f	604	/* Bump tot_len of whole chain, len of tail */
dirkx	0:355018f44c9f	605	for (p = last_unsent->p; p; p = p->next) {
dirkx	0:355018f44c9f	606	p->tot_len += oversize_used;
dirkx	0:355018f44c9f	607	if (p->next == NULL) {
dirkx	0:355018f44c9f	608	TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
dirkx	0:355018f44c9f	609	p->len += oversize_used;
dirkx	0:355018f44c9f	610	}
dirkx	0:355018f44c9f	611	}
dirkx	0:355018f44c9f	612	last_unsent->len += oversize_used;
dirkx	0:355018f44c9f	613	#if TCP_OVERSIZE_DBGCHECK
dirkx	0:355018f44c9f	614	last_unsent->oversize_left -= oversize_used;
dirkx	0:355018f44c9f	615	#endif /* TCP_OVERSIZE_DBGCHECK */
dirkx	0:355018f44c9f	616	}
dirkx	0:355018f44c9f	617	pcb->unsent_oversize = oversize;
dirkx	0:355018f44c9f	618	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	619
dirkx	0:355018f44c9f	620	/*
dirkx	0:355018f44c9f	621	* Phase 2: concat_p can be concatenated onto last_unsent->p
dirkx	0:355018f44c9f	622	*/
dirkx	0:355018f44c9f	623	if (concat_p != NULL) {
dirkx	0:355018f44c9f	624	LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
dirkx	0:355018f44c9f	625	(last_unsent != NULL));
dirkx	0:355018f44c9f	626	pbuf_cat(last_unsent->p, concat_p);
dirkx	0:355018f44c9f	627	last_unsent->len += concat_p->tot_len;
dirkx	0:355018f44c9f	628	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	629	if (concat_chksummed) {
dirkx	0:355018f44c9f	630	tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
dirkx	0:355018f44c9f	631	&last_unsent->chksum_swapped);
dirkx	0:355018f44c9f	632	last_unsent->flags \|= TF_SEG_DATA_CHECKSUMMED;
dirkx	0:355018f44c9f	633	}
dirkx	0:355018f44c9f	634	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	635	}
dirkx	0:355018f44c9f	636
dirkx	0:355018f44c9f	637	/*
dirkx	0:355018f44c9f	638	* Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
dirkx	0:355018f44c9f	639	* is harmless
dirkx	0:355018f44c9f	640	*/
dirkx	0:355018f44c9f	641	if (last_unsent == NULL) {
dirkx	0:355018f44c9f	642	pcb->unsent = queue;
dirkx	0:355018f44c9f	643	} else {
dirkx	0:355018f44c9f	644	last_unsent->next = queue;
dirkx	0:355018f44c9f	645	}
dirkx	0:355018f44c9f	646
dirkx	0:355018f44c9f	647	/*
dirkx	0:355018f44c9f	648	* Finally update the pcb state.
dirkx	0:355018f44c9f	649	*/
dirkx	0:355018f44c9f	650	pcb->snd_lbb += len;
dirkx	0:355018f44c9f	651	pcb->snd_buf -= len;
dirkx	0:355018f44c9f	652	pcb->snd_queuelen = queuelen;
dirkx	0:355018f44c9f	653
dirkx	0:355018f44c9f	654	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
dirkx	0:355018f44c9f	655	pcb->snd_queuelen));
dirkx	0:355018f44c9f	656	if (pcb->snd_queuelen != 0) {
dirkx	0:355018f44c9f	657	LWIP_ASSERT("tcp_write: valid queue length",
dirkx	0:355018f44c9f	658	pcb->unacked != NULL \|\| pcb->unsent != NULL);
dirkx	0:355018f44c9f	659	}
dirkx	0:355018f44c9f	660
dirkx	0:355018f44c9f	661	/* Set the PSH flag in the last segment that we enqueued. */
dirkx	0:355018f44c9f	662	if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
dirkx	0:355018f44c9f	663	TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
dirkx	0:355018f44c9f	664	}
dirkx	0:355018f44c9f	665
dirkx	0:355018f44c9f	666	return ERR_OK;
dirkx	0:355018f44c9f	667	memerr:
dirkx	0:355018f44c9f	668	pcb->flags \|= TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	669	TCP_STATS_INC(tcp.memerr);
dirkx	0:355018f44c9f	670
dirkx	0:355018f44c9f	671	if (concat_p != NULL) {
dirkx	0:355018f44c9f	672	pbuf_free(concat_p);
dirkx	0:355018f44c9f	673	}
dirkx	0:355018f44c9f	674	if (queue != NULL) {
dirkx	0:355018f44c9f	675	tcp_segs_free(queue);
dirkx	0:355018f44c9f	676	}
dirkx	0:355018f44c9f	677	if (pcb->snd_queuelen != 0) {
dirkx	0:355018f44c9f	678	LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL \|\|
dirkx	0:355018f44c9f	679	pcb->unsent != NULL);
dirkx	0:355018f44c9f	680	}
dirkx	0:355018f44c9f	681	LWIP_DEBUGF(TCP_QLEN_DEBUG \| LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
dirkx	0:355018f44c9f	682	return ERR_MEM;
dirkx	0:355018f44c9f	683	}
dirkx	0:355018f44c9f	684
dirkx	0:355018f44c9f	685	/**
dirkx	0:355018f44c9f	686	* Enqueue TCP options for transmission.
dirkx	0:355018f44c9f	687	*
dirkx	0:355018f44c9f	688	* Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
dirkx	0:355018f44c9f	689	*
dirkx	0:355018f44c9f	690	* @param pcb Protocol control block for the TCP connection.
dirkx	0:355018f44c9f	691	* @param flags TCP header flags to set in the outgoing segment.
dirkx	0:355018f44c9f	692	* @param optdata pointer to TCP options, or NULL.
dirkx	0:355018f44c9f	693	* @param optlen length of TCP options in bytes.
dirkx	0:355018f44c9f	694	*/
dirkx	0:355018f44c9f	695	err_t
dirkx	0:355018f44c9f	696	tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
dirkx	0:355018f44c9f	697	{
dirkx	0:355018f44c9f	698	struct pbuf *p;
dirkx	0:355018f44c9f	699	struct tcp_seg *seg;
dirkx	0:355018f44c9f	700	u8_t optflags = 0;
dirkx	0:355018f44c9f	701	u8_t optlen = 0;
dirkx	0:355018f44c9f	702
dirkx	0:355018f44c9f	703	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
dirkx	0:355018f44c9f	704
dirkx	0:355018f44c9f	705	LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
dirkx	0:355018f44c9f	706	(flags & (TCP_SYN \| TCP_FIN)) != 0);
dirkx	0:355018f44c9f	707
dirkx	0:355018f44c9f	708	/* check for configured max queuelen and possible overflow */
dirkx	0:355018f44c9f	709	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
dirkx	0:355018f44c9f	710	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
dirkx	0:355018f44c9f	711	pcb->snd_queuelen, TCP_SND_QUEUELEN));
dirkx	0:355018f44c9f	712	TCP_STATS_INC(tcp.memerr);
dirkx	0:355018f44c9f	713	pcb->flags \|= TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	714	return ERR_MEM;
dirkx	0:355018f44c9f	715	}
dirkx	0:355018f44c9f	716
dirkx	0:355018f44c9f	717	if (flags & TCP_SYN) {
dirkx	0:355018f44c9f	718	optflags = TF_SEG_OPTS_MSS;
dirkx	0:355018f44c9f	719	}
dirkx	0:355018f44c9f	720	#if LWIP_TCP_TIMESTAMPS
dirkx	0:355018f44c9f	721	if ((pcb->flags & TF_TIMESTAMP)) {
dirkx	0:355018f44c9f	722	optflags \|= TF_SEG_OPTS_TS;
dirkx	0:355018f44c9f	723	}
dirkx	0:355018f44c9f	724	#endif /* LWIP_TCP_TIMESTAMPS */
dirkx	0:355018f44c9f	725	optlen = LWIP_TCP_OPT_LENGTH(optflags);
dirkx	0:355018f44c9f	726
dirkx	0:355018f44c9f	727	/* tcp_enqueue_flags is always called with either SYN or FIN in flags.
dirkx	0:355018f44c9f	728	* We need one available snd_buf byte to do that.
dirkx	0:355018f44c9f	729	* This means we can't send FIN while snd_buf==0. A better fix would be to
dirkx	0:355018f44c9f	730	* not include SYN and FIN sequence numbers in the snd_buf count. */
dirkx	0:355018f44c9f	731	if (pcb->snd_buf == 0) {
dirkx	0:355018f44c9f	732	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: no send buffer available\n"));
dirkx	0:355018f44c9f	733	TCP_STATS_INC(tcp.memerr);
dirkx	0:355018f44c9f	734	return ERR_MEM;
dirkx	0:355018f44c9f	735	}
dirkx	0:355018f44c9f	736
dirkx	0:355018f44c9f	737	/* Allocate pbuf with room for TCP header + options */
dirkx	0:355018f44c9f	738	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
dirkx	0:355018f44c9f	739	pcb->flags \|= TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	740	TCP_STATS_INC(tcp.memerr);
dirkx	0:355018f44c9f	741	return ERR_MEM;
dirkx	0:355018f44c9f	742	}
dirkx	0:355018f44c9f	743	LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
dirkx	0:355018f44c9f	744	(p->len >= optlen));
dirkx	0:355018f44c9f	745
dirkx	0:355018f44c9f	746	/* Allocate memory for tcp_seg, and fill in fields. */
dirkx	0:355018f44c9f	747	if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
dirkx	0:355018f44c9f	748	pcb->flags \|= TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	749	TCP_STATS_INC(tcp.memerr);
dirkx	0:355018f44c9f	750	return ERR_MEM;
dirkx	0:355018f44c9f	751	}
dirkx	0:355018f44c9f	752	LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
dirkx	0:355018f44c9f	753
dirkx	0:355018f44c9f	754	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE,
dirkx	0:355018f44c9f	755	("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
dirkx	0:355018f44c9f	756	ntohl(seg->tcphdr->seqno),
dirkx	0:355018f44c9f	757	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
dirkx	0:355018f44c9f	758	(u16_t)flags));
dirkx	0:355018f44c9f	759
dirkx	0:355018f44c9f	760	/* Now append seg to pcb->unsent queue */
dirkx	0:355018f44c9f	761	if (pcb->unsent == NULL) {
dirkx	0:355018f44c9f	762	pcb->unsent = seg;
dirkx	0:355018f44c9f	763	} else {
dirkx	0:355018f44c9f	764	struct tcp_seg *useg;
dirkx	0:355018f44c9f	765	for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
dirkx	0:355018f44c9f	766	useg->next = seg;
dirkx	0:355018f44c9f	767	}
dirkx	0:355018f44c9f	768	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	769	/* The new unsent tail has no space */
dirkx	0:355018f44c9f	770	pcb->unsent_oversize = 0;
dirkx	0:355018f44c9f	771	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	772
dirkx	0:355018f44c9f	773	/* SYN and FIN bump the sequence number */
dirkx	0:355018f44c9f	774	if ((flags & TCP_SYN) \|\| (flags & TCP_FIN)) {
dirkx	0:355018f44c9f	775	pcb->snd_lbb++;
dirkx	0:355018f44c9f	776	/* optlen does not influence snd_buf */
dirkx	0:355018f44c9f	777	pcb->snd_buf--;
dirkx	0:355018f44c9f	778	}
dirkx	0:355018f44c9f	779	if (flags & TCP_FIN) {
dirkx	0:355018f44c9f	780	pcb->flags \|= TF_FIN;
dirkx	0:355018f44c9f	781	}
dirkx	0:355018f44c9f	782
dirkx	0:355018f44c9f	783	/* update number of segments on the queues */
dirkx	0:355018f44c9f	784	pcb->snd_queuelen += pbuf_clen(seg->p);
dirkx	0:355018f44c9f	785	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
dirkx	0:355018f44c9f	786	if (pcb->snd_queuelen != 0) {
dirkx	0:355018f44c9f	787	LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
dirkx	0:355018f44c9f	788	pcb->unacked != NULL \|\| pcb->unsent != NULL);
dirkx	0:355018f44c9f	789	}
dirkx	0:355018f44c9f	790
dirkx	0:355018f44c9f	791	return ERR_OK;
dirkx	0:355018f44c9f	792	}
dirkx	0:355018f44c9f	793
dirkx	0:355018f44c9f	794
dirkx	0:355018f44c9f	795	#if LWIP_TCP_TIMESTAMPS
dirkx	0:355018f44c9f	796	/* Build a timestamp option (12 bytes long) at the specified options pointer)
dirkx	0:355018f44c9f	797	*
dirkx	0:355018f44c9f	798	* @param pcb tcp_pcb
dirkx	0:355018f44c9f	799	* @param opts option pointer where to store the timestamp option
dirkx	0:355018f44c9f	800	*/
dirkx	0:355018f44c9f	801	static void
dirkx	0:355018f44c9f	802	tcp_build_timestamp_option(struct tcp_pcb pcb, u32_t opts)
dirkx	0:355018f44c9f	803	{
dirkx	0:355018f44c9f	804	/* Pad with two NOP options to make everything nicely aligned */
dirkx	0:355018f44c9f	805	opts[0] = htonl(0x0101080A);
dirkx	0:355018f44c9f	806	opts[1] = htonl(sys_now());
dirkx	0:355018f44c9f	807	opts[2] = htonl(pcb->ts_recent);
dirkx	0:355018f44c9f	808	}
dirkx	0:355018f44c9f	809	#endif
dirkx	0:355018f44c9f	810
dirkx	0:355018f44c9f	811	/** Send an ACK without data.
dirkx	0:355018f44c9f	812	*
dirkx	0:355018f44c9f	813	* @param pcb Protocol control block for the TCP connection to send the ACK
dirkx	0:355018f44c9f	814	*/
dirkx	0:355018f44c9f	815	err_t
dirkx	0:355018f44c9f	816	tcp_send_empty_ack(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	817	{
dirkx	0:355018f44c9f	818	struct pbuf *p;
dirkx	0:355018f44c9f	819	struct tcp_hdr *tcphdr;
dirkx	0:355018f44c9f	820	u8_t optlen = 0;
dirkx	0:355018f44c9f	821
dirkx	0:355018f44c9f	822	#if LWIP_TCP_TIMESTAMPS
dirkx	0:355018f44c9f	823	if (pcb->flags & TF_TIMESTAMP) {
dirkx	0:355018f44c9f	824	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
dirkx	0:355018f44c9f	825	}
dirkx	0:355018f44c9f	826	#endif
dirkx	0:355018f44c9f	827
dirkx	0:355018f44c9f	828	p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
dirkx	0:355018f44c9f	829	if (p == NULL) {
dirkx	0:355018f44c9f	830	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
dirkx	0:355018f44c9f	831	return ERR_BUF;
dirkx	0:355018f44c9f	832	}
dirkx	0:355018f44c9f	833	tcphdr = (struct tcp_hdr *)p->payload;
dirkx	0:355018f44c9f	834	LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
dirkx	0:355018f44c9f	835	("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
dirkx	0:355018f44c9f	836	/* remove ACK flags from the PCB, as we send an empty ACK now */
dirkx	0:355018f44c9f	837	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
dirkx	0:355018f44c9f	838
dirkx	0:355018f44c9f	839	/* NB. MSS option is only sent on SYNs, so ignore it here */
dirkx	0:355018f44c9f	840	#if LWIP_TCP_TIMESTAMPS
dirkx	0:355018f44c9f	841	pcb->ts_lastacksent = pcb->rcv_nxt;
dirkx	0:355018f44c9f	842
dirkx	0:355018f44c9f	843	if (pcb->flags & TF_TIMESTAMP) {
dirkx	0:355018f44c9f	844	tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
dirkx	0:355018f44c9f	845	}
dirkx	0:355018f44c9f	846	#endif
dirkx	0:355018f44c9f	847
dirkx	0:355018f44c9f	848	#if CHECKSUM_GEN_TCP
dirkx	0:355018f44c9f	849	tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
dirkx	0:355018f44c9f	850	IP_PROTO_TCP, p->tot_len);
dirkx	0:355018f44c9f	851	#endif
dirkx	0:355018f44c9f	852	#if LWIP_NETIF_HWADDRHINT
dirkx	0:355018f44c9f	853	ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
dirkx	0:355018f44c9f	854	IP_PROTO_TCP, &(pcb->addr_hint));
dirkx	0:355018f44c9f	855	#else /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	856	ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
dirkx	0:355018f44c9f	857	IP_PROTO_TCP);
dirkx	0:355018f44c9f	858	#endif /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	859	pbuf_free(p);
dirkx	0:355018f44c9f	860
dirkx	0:355018f44c9f	861	return ERR_OK;
dirkx	0:355018f44c9f	862	}
dirkx	0:355018f44c9f	863
dirkx	0:355018f44c9f	864	/**
dirkx	0:355018f44c9f	865	* Find out what we can send and send it
dirkx	0:355018f44c9f	866	*
dirkx	0:355018f44c9f	867	* @param pcb Protocol control block for the TCP connection to send data
dirkx	0:355018f44c9f	868	* @return ERR_OK if data has been sent or nothing to send
dirkx	0:355018f44c9f	869	* another err_t on error
dirkx	0:355018f44c9f	870	*/
dirkx	0:355018f44c9f	871	err_t
dirkx	0:355018f44c9f	872	tcp_output(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	873	{
dirkx	0:355018f44c9f	874	struct tcp_seg seg, useg;
dirkx	0:355018f44c9f	875	u32_t wnd, snd_nxt;
dirkx	0:355018f44c9f	876	#if TCP_CWND_DEBUG
dirkx	0:355018f44c9f	877	s16_t i = 0;
dirkx	0:355018f44c9f	878	#endif /* TCP_CWND_DEBUG */
dirkx	0:355018f44c9f	879
dirkx	0:355018f44c9f	880	/* First, check if we are invoked by the TCP input processing
dirkx	0:355018f44c9f	881	code. If so, we do not output anything. Instead, we rely on the
dirkx	0:355018f44c9f	882	input processing code to call us when input processing is done
dirkx	0:355018f44c9f	883	with. */
dirkx	0:355018f44c9f	884	if (tcp_input_pcb == pcb) {
dirkx	0:355018f44c9f	885	return ERR_OK;
dirkx	0:355018f44c9f	886	}
dirkx	0:355018f44c9f	887
dirkx	0:355018f44c9f	888	wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
dirkx	0:355018f44c9f	889
dirkx	0:355018f44c9f	890	seg = pcb->unsent;
dirkx	0:355018f44c9f	891
dirkx	0:355018f44c9f	892	/* If the TF_ACK_NOW flag is set and no data will be sent (either
dirkx	0:355018f44c9f	893	* because the ->unsent queue is empty or because the window does
dirkx	0:355018f44c9f	894	* not allow it), construct an empty ACK segment and send it.
dirkx	0:355018f44c9f	895	*
dirkx	0:355018f44c9f	896	* If data is to be sent, we will just piggyback the ACK (see below).
dirkx	0:355018f44c9f	897	*/
dirkx	0:355018f44c9f	898	if (pcb->flags & TF_ACK_NOW &&
dirkx	0:355018f44c9f	899	(seg == NULL \|\|
dirkx	0:355018f44c9f	900	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
dirkx	0:355018f44c9f	901	return tcp_send_empty_ack(pcb);
dirkx	0:355018f44c9f	902	}
dirkx	0:355018f44c9f	903
dirkx	0:355018f44c9f	904	/* useg should point to last segment on unacked queue */
dirkx	0:355018f44c9f	905	useg = pcb->unacked;
dirkx	0:355018f44c9f	906	if (useg != NULL) {
dirkx	0:355018f44c9f	907	for (; useg->next != NULL; useg = useg->next);
dirkx	0:355018f44c9f	908	}
dirkx	0:355018f44c9f	909
dirkx	0:355018f44c9f	910	#if TCP_OUTPUT_DEBUG
dirkx	0:355018f44c9f	911	if (seg == NULL) {
dirkx	0:355018f44c9f	912	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
dirkx	0:355018f44c9f	913	(void*)pcb->unsent));
dirkx	0:355018f44c9f	914	}
dirkx	0:355018f44c9f	915	#endif /* TCP_OUTPUT_DEBUG */
dirkx	0:355018f44c9f	916	#if TCP_CWND_DEBUG
dirkx	0:355018f44c9f	917	if (seg == NULL) {
dirkx	0:355018f44c9f	918	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
dirkx	0:355018f44c9f	919	", cwnd %"U16_F", wnd %"U32_F
dirkx	0:355018f44c9f	920	", seg == NULL, ack %"U32_F"\n",
dirkx	0:355018f44c9f	921	pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
dirkx	0:355018f44c9f	922	} else {
dirkx	0:355018f44c9f	923	LWIP_DEBUGF(TCP_CWND_DEBUG,
dirkx	0:355018f44c9f	924	("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
dirkx	0:355018f44c9f	925	", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
dirkx	0:355018f44c9f	926	pcb->snd_wnd, pcb->cwnd, wnd,
dirkx	0:355018f44c9f	927	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
dirkx	0:355018f44c9f	928	ntohl(seg->tcphdr->seqno), pcb->lastack));
dirkx	0:355018f44c9f	929	}
dirkx	0:355018f44c9f	930	#endif /* TCP_CWND_DEBUG */
dirkx	0:355018f44c9f	931	/* data available and window allows it to be sent? */
dirkx	0:355018f44c9f	932	while (seg != NULL &&
dirkx	0:355018f44c9f	933	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
dirkx	0:355018f44c9f	934	LWIP_ASSERT("RST not expected here!",
dirkx	0:355018f44c9f	935	(TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
dirkx	0:355018f44c9f	936	/* Stop sending if the nagle algorithm would prevent it
dirkx	0:355018f44c9f	937	* Don't stop:
dirkx	0:355018f44c9f	938	* - if tcp_write had a memory error before (prevent delayed ACK timeout) or
dirkx	0:355018f44c9f	939	* - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
dirkx	0:355018f44c9f	940	* either seg->next != NULL or pcb->unacked == NULL;
dirkx	0:355018f44c9f	941	* RST is no sent using tcp_write/tcp_output.
dirkx	0:355018f44c9f	942	*/
dirkx	0:355018f44c9f	943	if((tcp_do_output_nagle(pcb) == 0) &&
dirkx	0:355018f44c9f	944	((pcb->flags & (TF_NAGLEMEMERR \| TF_FIN)) == 0)){
dirkx	0:355018f44c9f	945	break;
dirkx	0:355018f44c9f	946	}
dirkx	0:355018f44c9f	947	#if TCP_CWND_DEBUG
dirkx	0:355018f44c9f	948	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",
dirkx	0:355018f44c9f	949	pcb->snd_wnd, pcb->cwnd, wnd,
dirkx	0:355018f44c9f	950	ntohl(seg->tcphdr->seqno) + seg->len -
dirkx	0:355018f44c9f	951	pcb->lastack,
dirkx	0:355018f44c9f	952	ntohl(seg->tcphdr->seqno), pcb->lastack, i));
dirkx	0:355018f44c9f	953	++i;
dirkx	0:355018f44c9f	954	#endif /* TCP_CWND_DEBUG */
dirkx	0:355018f44c9f	955
dirkx	0:355018f44c9f	956	pcb->unsent = seg->next;
dirkx	0:355018f44c9f	957
dirkx	0:355018f44c9f	958	if (pcb->state != SYN_SENT) {
dirkx	0:355018f44c9f	959	TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
dirkx	0:355018f44c9f	960	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
dirkx	0:355018f44c9f	961	}
dirkx	0:355018f44c9f	962
dirkx	0:355018f44c9f	963	tcp_output_segment(seg, pcb);
dirkx	0:355018f44c9f	964	snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
dirkx	0:355018f44c9f	965	if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
dirkx	0:355018f44c9f	966	pcb->snd_nxt = snd_nxt;
dirkx	0:355018f44c9f	967	}
dirkx	0:355018f44c9f	968	/* put segment on unacknowledged list if length > 0 */
dirkx	0:355018f44c9f	969	if (TCP_TCPLEN(seg) > 0) {
dirkx	0:355018f44c9f	970	seg->next = NULL;
dirkx	0:355018f44c9f	971	/* unacked list is empty? */
dirkx	0:355018f44c9f	972	if (pcb->unacked == NULL) {
dirkx	0:355018f44c9f	973	pcb->unacked = seg;
dirkx	0:355018f44c9f	974	useg = seg;
dirkx	0:355018f44c9f	975	/* unacked list is not empty? */
dirkx	0:355018f44c9f	976	} else {
dirkx	0:355018f44c9f	977	/* In the case of fast retransmit, the packet should not go to the tail
dirkx	0:355018f44c9f	978	* of the unacked queue, but rather somewhere before it. We need to check for
dirkx	0:355018f44c9f	979	* this case. -STJ Jul 27, 2004 */
dirkx	0:355018f44c9f	980	if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
dirkx	0:355018f44c9f	981	/* add segment to before tail of unacked list, keeping the list sorted */
dirkx	0:355018f44c9f	982	struct tcp_seg **cur_seg = &(pcb->unacked);
dirkx	0:355018f44c9f	983	while (*cur_seg &&
dirkx	0:355018f44c9f	984	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
dirkx	0:355018f44c9f	985	cur_seg = &((*cur_seg)->next );
dirkx	0:355018f44c9f	986	}
dirkx	0:355018f44c9f	987	seg->next = (*cur_seg);
dirkx	0:355018f44c9f	988	(*cur_seg) = seg;
dirkx	0:355018f44c9f	989	} else {
dirkx	0:355018f44c9f	990	/* add segment to tail of unacked list */
dirkx	0:355018f44c9f	991	useg->next = seg;
dirkx	0:355018f44c9f	992	useg = useg->next;
dirkx	0:355018f44c9f	993	}
dirkx	0:355018f44c9f	994	}
dirkx	0:355018f44c9f	995	/* do not queue empty segments on the unacked list */
dirkx	0:355018f44c9f	996	} else {
dirkx	0:355018f44c9f	997	tcp_seg_free(seg);
dirkx	0:355018f44c9f	998	}
dirkx	0:355018f44c9f	999	seg = pcb->unsent;
dirkx	0:355018f44c9f	1000	}
dirkx	0:355018f44c9f	1001	#if TCP_OVERSIZE
dirkx	0:355018f44c9f	1002	if (pcb->unsent == NULL) {
dirkx	0:355018f44c9f	1003	/* last unsent has been removed, reset unsent_oversize */
dirkx	0:355018f44c9f	1004	pcb->unsent_oversize = 0;
dirkx	0:355018f44c9f	1005	}
dirkx	0:355018f44c9f	1006	#endif /* TCP_OVERSIZE */
dirkx	0:355018f44c9f	1007
dirkx	0:355018f44c9f	1008	if (seg != NULL && pcb->persist_backoff == 0 &&
dirkx	0:355018f44c9f	1009	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) {
dirkx	0:355018f44c9f	1010	/* prepare for persist timer */
dirkx	0:355018f44c9f	1011	pcb->persist_cnt = 0;
dirkx	0:355018f44c9f	1012	pcb->persist_backoff = 1;
dirkx	0:355018f44c9f	1013	}
dirkx	0:355018f44c9f	1014
dirkx	0:355018f44c9f	1015	pcb->flags &= ~TF_NAGLEMEMERR;
dirkx	0:355018f44c9f	1016	return ERR_OK;
dirkx	0:355018f44c9f	1017	}
dirkx	0:355018f44c9f	1018
dirkx	0:355018f44c9f	1019	/**
dirkx	0:355018f44c9f	1020	* Called by tcp_output() to actually send a TCP segment over IP.
dirkx	0:355018f44c9f	1021	*
dirkx	0:355018f44c9f	1022	* @param seg the tcp_seg to send
dirkx	0:355018f44c9f	1023	* @param pcb the tcp_pcb for the TCP connection used to send the segment
dirkx	0:355018f44c9f	1024	*/
dirkx	0:355018f44c9f	1025	static void
dirkx	0:355018f44c9f	1026	tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb)
dirkx	0:355018f44c9f	1027	{
dirkx	0:355018f44c9f	1028	u16_t len;
dirkx	0:355018f44c9f	1029	struct netif *netif;
dirkx	0:355018f44c9f	1030	u32_t *opts;
dirkx	0:355018f44c9f	1031
dirkx	0:355018f44c9f	1032	/** @bug Exclude retransmitted segments from this count. */
dirkx	0:355018f44c9f	1033	snmp_inc_tcpoutsegs();
dirkx	0:355018f44c9f	1034
dirkx	0:355018f44c9f	1035	/* The TCP header has already been constructed, but the ackno and
dirkx	0:355018f44c9f	1036	wnd fields remain. */
dirkx	0:355018f44c9f	1037	seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
dirkx	0:355018f44c9f	1038
dirkx	0:355018f44c9f	1039	/* advertise our receive window size in this TCP segment */
dirkx	0:355018f44c9f	1040	seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
dirkx	0:355018f44c9f	1041
dirkx	0:355018f44c9f	1042	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
dirkx	0:355018f44c9f	1043
dirkx	0:355018f44c9f	1044	/* Add any requested options. NB MSS option is only set on SYN
dirkx	0:355018f44c9f	1045	packets, so ignore it here */
dirkx	0:355018f44c9f	1046	LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
dirkx	0:355018f44c9f	1047	opts = (u32_t )(void )(seg->tcphdr + 1);
dirkx	0:355018f44c9f	1048	if (seg->flags & TF_SEG_OPTS_MSS) {
dirkx	0:355018f44c9f	1049	TCP_BUILD_MSS_OPTION(*opts);
dirkx	0:355018f44c9f	1050	opts += 1;
dirkx	0:355018f44c9f	1051	}
dirkx	0:355018f44c9f	1052	#if LWIP_TCP_TIMESTAMPS
dirkx	0:355018f44c9f	1053	pcb->ts_lastacksent = pcb->rcv_nxt;
dirkx	0:355018f44c9f	1054
dirkx	0:355018f44c9f	1055	if (seg->flags & TF_SEG_OPTS_TS) {
dirkx	0:355018f44c9f	1056	tcp_build_timestamp_option(pcb, opts);
dirkx	0:355018f44c9f	1057	opts += 3;
dirkx	0:355018f44c9f	1058	}
dirkx	0:355018f44c9f	1059	#endif
dirkx	0:355018f44c9f	1060
dirkx	0:355018f44c9f	1061	/* If we don't have a local IP address, we get one by
dirkx	0:355018f44c9f	1062	calling ip_route(). */
dirkx	0:355018f44c9f	1063	if (ip_addr_isany(&(pcb->local_ip))) {
dirkx	0:355018f44c9f	1064	netif = ip_route(&(pcb->remote_ip));
dirkx	0:355018f44c9f	1065	if (netif == NULL) {
dirkx	0:355018f44c9f	1066	return;
dirkx	0:355018f44c9f	1067	}
dirkx	0:355018f44c9f	1068	ip_addr_copy(pcb->local_ip, netif->ip_addr);
dirkx	0:355018f44c9f	1069	}
dirkx	0:355018f44c9f	1070
dirkx	0:355018f44c9f	1071	/* Set retransmission timer running if it is not currently enabled */
dirkx	0:355018f44c9f	1072	if(pcb->rtime == -1) {
dirkx	0:355018f44c9f	1073	pcb->rtime = 0;
dirkx	0:355018f44c9f	1074	}
dirkx	0:355018f44c9f	1075
dirkx	0:355018f44c9f	1076	if (pcb->rttest == 0) {
dirkx	0:355018f44c9f	1077	pcb->rttest = tcp_ticks;
dirkx	0:355018f44c9f	1078	pcb->rtseq = ntohl(seg->tcphdr->seqno);
dirkx	0:355018f44c9f	1079
dirkx	0:355018f44c9f	1080	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
dirkx	0:355018f44c9f	1081	}
dirkx	0:355018f44c9f	1082	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
dirkx	0:355018f44c9f	1083	htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
dirkx	0:355018f44c9f	1084	seg->len));
dirkx	0:355018f44c9f	1085
dirkx	0:355018f44c9f	1086	len = (u16_t)((u8_t )seg->tcphdr - (u8_t )seg->p->payload);
dirkx	0:355018f44c9f	1087
dirkx	0:355018f44c9f	1088	seg->p->len -= len;
dirkx	0:355018f44c9f	1089	seg->p->tot_len -= len;
dirkx	0:355018f44c9f	1090
dirkx	0:355018f44c9f	1091	seg->p->payload = seg->tcphdr;
dirkx	0:355018f44c9f	1092
dirkx	0:355018f44c9f	1093	seg->tcphdr->chksum = 0;
dirkx	0:355018f44c9f	1094	#if CHECKSUM_GEN_TCP
dirkx	0:355018f44c9f	1095	#if TCP_CHECKSUM_ON_COPY
dirkx	0:355018f44c9f	1096	{
dirkx	0:355018f44c9f	1097	u32_t acc;
dirkx	0:355018f44c9f	1098	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
dirkx	0:355018f44c9f	1099	u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
dirkx	0:355018f44c9f	1100	&(pcb->remote_ip),
dirkx	0:355018f44c9f	1101	IP_PROTO_TCP, seg->p->tot_len);
dirkx	0:355018f44c9f	1102	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
dirkx	0:355018f44c9f	1103	if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
dirkx	0:355018f44c9f	1104	LWIP_ASSERT("data included but not checksummed",
dirkx	0:355018f44c9f	1105	seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
dirkx	0:355018f44c9f	1106	}
dirkx	0:355018f44c9f	1107
dirkx	0:355018f44c9f	1108	/* rebuild TCP header checksum (TCP header changes for retransmissions!) */
dirkx	0:355018f44c9f	1109	acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
dirkx	0:355018f44c9f	1110	&(pcb->remote_ip),
dirkx	0:355018f44c9f	1111	IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
dirkx	0:355018f44c9f	1112	/* add payload checksum */
dirkx	0:355018f44c9f	1113	if (seg->chksum_swapped) {
dirkx	0:355018f44c9f	1114	seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
dirkx	0:355018f44c9f	1115	seg->chksum_swapped = 0;
dirkx	0:355018f44c9f	1116	}
dirkx	0:355018f44c9f	1117	acc += (u16_t)~(seg->chksum);
dirkx	0:355018f44c9f	1118	seg->tcphdr->chksum = FOLD_U32T(acc);
dirkx	0:355018f44c9f	1119	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
dirkx	0:355018f44c9f	1120	if (chksum_slow != seg->tcphdr->chksum) {
dirkx	0:355018f44c9f	1121	LWIP_DEBUGF(TCP_DEBUG \| LWIP_DBG_LEVEL_WARNING,
dirkx	0:355018f44c9f	1122	("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
dirkx	0:355018f44c9f	1123	seg->tcphdr->chksum, chksum_slow));
dirkx	0:355018f44c9f	1124	seg->tcphdr->chksum = chksum_slow;
dirkx	0:355018f44c9f	1125	}
dirkx	0:355018f44c9f	1126	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
dirkx	0:355018f44c9f	1127	}
dirkx	0:355018f44c9f	1128	#else /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	1129	seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
dirkx	0:355018f44c9f	1130	&(pcb->remote_ip),
dirkx	0:355018f44c9f	1131	IP_PROTO_TCP, seg->p->tot_len);
dirkx	0:355018f44c9f	1132	#endif /* TCP_CHECKSUM_ON_COPY */
dirkx	0:355018f44c9f	1133	#endif /* CHECKSUM_GEN_TCP */
dirkx	0:355018f44c9f	1134	TCP_STATS_INC(tcp.xmit);
dirkx	0:355018f44c9f	1135
dirkx	0:355018f44c9f	1136	#if LWIP_NETIF_HWADDRHINT
dirkx	0:355018f44c9f	1137	ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
dirkx	0:355018f44c9f	1138	IP_PROTO_TCP, &(pcb->addr_hint));
dirkx	0:355018f44c9f	1139	#else /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	1140	ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
dirkx	0:355018f44c9f	1141	IP_PROTO_TCP);
dirkx	0:355018f44c9f	1142	#endif /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	1143	}
dirkx	0:355018f44c9f	1144
dirkx	0:355018f44c9f	1145	/**
dirkx	0:355018f44c9f	1146	* Send a TCP RESET packet (empty segment with RST flag set) either to
dirkx	0:355018f44c9f	1147	* abort a connection or to show that there is no matching local connection
dirkx	0:355018f44c9f	1148	* for a received segment.
dirkx	0:355018f44c9f	1149	*
dirkx	0:355018f44c9f	1150	* Called by tcp_abort() (to abort a local connection), tcp_input() (if no
dirkx	0:355018f44c9f	1151	* matching local pcb was found), tcp_listen_input() (if incoming segment
dirkx	0:355018f44c9f	1152	* has ACK flag set) and tcp_process() (received segment in the wrong state)
dirkx	0:355018f44c9f	1153	*
dirkx	0:355018f44c9f	1154	* Since a RST segment is in most cases not sent for an active connection,
dirkx	0:355018f44c9f	1155	* tcp_rst() has a number of arguments that are taken from a tcp_pcb for
dirkx	0:355018f44c9f	1156	* most other segment output functions.
dirkx	0:355018f44c9f	1157	*
dirkx	0:355018f44c9f	1158	* @param seqno the sequence number to use for the outgoing segment
dirkx	0:355018f44c9f	1159	* @param ackno the acknowledge number to use for the outgoing segment
dirkx	0:355018f44c9f	1160	* @param local_ip the local IP address to send the segment from
dirkx	0:355018f44c9f	1161	* @param remote_ip the remote IP address to send the segment to
dirkx	0:355018f44c9f	1162	* @param local_port the local TCP port to send the segment from
dirkx	0:355018f44c9f	1163	* @param remote_port the remote TCP port to send the segment to
dirkx	0:355018f44c9f	1164	*/
dirkx	0:355018f44c9f	1165	void
dirkx	0:355018f44c9f	1166	tcp_rst(u32_t seqno, u32_t ackno,
dirkx	0:355018f44c9f	1167	ip_addr_t local_ip, ip_addr_t remote_ip,
dirkx	0:355018f44c9f	1168	u16_t local_port, u16_t remote_port)
dirkx	0:355018f44c9f	1169	{
dirkx	0:355018f44c9f	1170	struct pbuf *p;
dirkx	0:355018f44c9f	1171	struct tcp_hdr *tcphdr;
dirkx	0:355018f44c9f	1172	p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
dirkx	0:355018f44c9f	1173	if (p == NULL) {
dirkx	0:355018f44c9f	1174	LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
dirkx	0:355018f44c9f	1175	return;
dirkx	0:355018f44c9f	1176	}
dirkx	0:355018f44c9f	1177	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
dirkx	0:355018f44c9f	1178	(p->len >= sizeof(struct tcp_hdr)));
dirkx	0:355018f44c9f	1179
dirkx	0:355018f44c9f	1180	tcphdr = (struct tcp_hdr *)p->payload;
dirkx	0:355018f44c9f	1181	tcphdr->src = htons(local_port);
dirkx	0:355018f44c9f	1182	tcphdr->dest = htons(remote_port);
dirkx	0:355018f44c9f	1183	tcphdr->seqno = htonl(seqno);
dirkx	0:355018f44c9f	1184	tcphdr->ackno = htonl(ackno);
dirkx	0:355018f44c9f	1185	TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST \| TCP_ACK);
dirkx	0:355018f44c9f	1186	tcphdr->wnd = htons(TCP_WND);
dirkx	0:355018f44c9f	1187	tcphdr->chksum = 0;
dirkx	0:355018f44c9f	1188	tcphdr->urgp = 0;
dirkx	0:355018f44c9f	1189
dirkx	0:355018f44c9f	1190	#if CHECKSUM_GEN_TCP
dirkx	0:355018f44c9f	1191	tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
dirkx	0:355018f44c9f	1192	IP_PROTO_TCP, p->tot_len);
dirkx	0:355018f44c9f	1193	#endif
dirkx	0:355018f44c9f	1194	TCP_STATS_INC(tcp.xmit);
dirkx	0:355018f44c9f	1195	snmp_inc_tcpoutrsts();
dirkx	0:355018f44c9f	1196	/* Send output with hardcoded TTL since we have no access to the pcb */
dirkx	0:355018f44c9f	1197	ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
dirkx	0:355018f44c9f	1198	pbuf_free(p);
dirkx	0:355018f44c9f	1199	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
dirkx	0:355018f44c9f	1200	}
dirkx	0:355018f44c9f	1201
dirkx	0:355018f44c9f	1202	/**
dirkx	0:355018f44c9f	1203	* Requeue all unacked segments for retransmission
dirkx	0:355018f44c9f	1204	*
dirkx	0:355018f44c9f	1205	* Called by tcp_slowtmr() for slow retransmission.
dirkx	0:355018f44c9f	1206	*
dirkx	0:355018f44c9f	1207	* @param pcb the tcp_pcb for which to re-enqueue all unacked segments
dirkx	0:355018f44c9f	1208	*/
dirkx	0:355018f44c9f	1209	void
dirkx	0:355018f44c9f	1210	tcp_rexmit_rto(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	1211	{
dirkx	0:355018f44c9f	1212	struct tcp_seg *seg;
dirkx	0:355018f44c9f	1213
dirkx	0:355018f44c9f	1214	if (pcb->unacked == NULL) {
dirkx	0:355018f44c9f	1215	return;
dirkx	0:355018f44c9f	1216	}
dirkx	0:355018f44c9f	1217
dirkx	0:355018f44c9f	1218	/* Move all unacked segments to the head of the unsent queue */
dirkx	0:355018f44c9f	1219	for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
dirkx	0:355018f44c9f	1220	/* concatenate unsent queue after unacked queue */
dirkx	0:355018f44c9f	1221	seg->next = pcb->unsent;
dirkx	0:355018f44c9f	1222	/* unsent queue is the concatenated queue (of unacked, unsent) */
dirkx	0:355018f44c9f	1223	pcb->unsent = pcb->unacked;
dirkx	0:355018f44c9f	1224	/* unacked queue is now empty */
dirkx	0:355018f44c9f	1225	pcb->unacked = NULL;
dirkx	0:355018f44c9f	1226
dirkx	0:355018f44c9f	1227	/* increment number of retransmissions */
dirkx	0:355018f44c9f	1228	++pcb->nrtx;
dirkx	0:355018f44c9f	1229
dirkx	0:355018f44c9f	1230	/* Don't take any RTT measurements after retransmitting. */
dirkx	0:355018f44c9f	1231	pcb->rttest = 0;
dirkx	0:355018f44c9f	1232
dirkx	0:355018f44c9f	1233	/* Do the actual retransmission */
dirkx	0:355018f44c9f	1234	tcp_output(pcb);
dirkx	0:355018f44c9f	1235	}
dirkx	0:355018f44c9f	1236
dirkx	0:355018f44c9f	1237	/**
dirkx	0:355018f44c9f	1238	* Requeue the first unacked segment for retransmission
dirkx	0:355018f44c9f	1239	*
dirkx	0:355018f44c9f	1240	* Called by tcp_receive() for fast retramsmit.
dirkx	0:355018f44c9f	1241	*
dirkx	0:355018f44c9f	1242	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
dirkx	0:355018f44c9f	1243	*/
dirkx	0:355018f44c9f	1244	void
dirkx	0:355018f44c9f	1245	tcp_rexmit(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	1246	{
dirkx	0:355018f44c9f	1247	struct tcp_seg *seg;
dirkx	0:355018f44c9f	1248	struct tcp_seg **cur_seg;
dirkx	0:355018f44c9f	1249
dirkx	0:355018f44c9f	1250	if (pcb->unacked == NULL) {
dirkx	0:355018f44c9f	1251	return;
dirkx	0:355018f44c9f	1252	}
dirkx	0:355018f44c9f	1253
dirkx	0:355018f44c9f	1254	/* Move the first unacked segment to the unsent queue */
dirkx	0:355018f44c9f	1255	/* Keep the unsent queue sorted. */
dirkx	0:355018f44c9f	1256	seg = pcb->unacked;
dirkx	0:355018f44c9f	1257	pcb->unacked = seg->next;
dirkx	0:355018f44c9f	1258
dirkx	0:355018f44c9f	1259	cur_seg = &(pcb->unsent);
dirkx	0:355018f44c9f	1260	while (*cur_seg &&
dirkx	0:355018f44c9f	1261	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
dirkx	0:355018f44c9f	1262	cur_seg = &((*cur_seg)->next );
dirkx	0:355018f44c9f	1263	}
dirkx	0:355018f44c9f	1264	seg->next = *cur_seg;
dirkx	0:355018f44c9f	1265	*cur_seg = seg;
dirkx	0:355018f44c9f	1266
dirkx	0:355018f44c9f	1267	++pcb->nrtx;
dirkx	0:355018f44c9f	1268
dirkx	0:355018f44c9f	1269	/* Don't take any rtt measurements after retransmitting. */
dirkx	0:355018f44c9f	1270	pcb->rttest = 0;
dirkx	0:355018f44c9f	1271
dirkx	0:355018f44c9f	1272	/* Do the actual retransmission. */
dirkx	0:355018f44c9f	1273	snmp_inc_tcpretranssegs();
dirkx	0:355018f44c9f	1274	/* No need to call tcp_output: we are always called from tcp_input()
dirkx	0:355018f44c9f	1275	and thus tcp_output directly returns. */
dirkx	0:355018f44c9f	1276	}
dirkx	0:355018f44c9f	1277
dirkx	0:355018f44c9f	1278
dirkx	0:355018f44c9f	1279	/**
dirkx	0:355018f44c9f	1280	* Handle retransmission after three dupacks received
dirkx	0:355018f44c9f	1281	*
dirkx	0:355018f44c9f	1282	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
dirkx	0:355018f44c9f	1283	*/
dirkx	0:355018f44c9f	1284	void
dirkx	0:355018f44c9f	1285	tcp_rexmit_fast(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	1286	{
dirkx	0:355018f44c9f	1287	if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
dirkx	0:355018f44c9f	1288	/* This is fast retransmit. Retransmit the first unacked segment. */
dirkx	0:355018f44c9f	1289	LWIP_DEBUGF(TCP_FR_DEBUG,
dirkx	0:355018f44c9f	1290	("tcp_receive: dupacks %"U16_F" (%"U32_F
dirkx	0:355018f44c9f	1291	"), fast retransmit %"U32_F"\n",
dirkx	0:355018f44c9f	1292	(u16_t)pcb->dupacks, pcb->lastack,
dirkx	0:355018f44c9f	1293	ntohl(pcb->unacked->tcphdr->seqno)));
dirkx	0:355018f44c9f	1294	tcp_rexmit(pcb);
dirkx	0:355018f44c9f	1295
dirkx	0:355018f44c9f	1296	/* Set ssthresh to half of the minimum of the current
dirkx	0:355018f44c9f	1297	* cwnd and the advertised window */
dirkx	0:355018f44c9f	1298	if (pcb->cwnd > pcb->snd_wnd) {
dirkx	0:355018f44c9f	1299	pcb->ssthresh = pcb->snd_wnd / 2;
dirkx	0:355018f44c9f	1300	} else {
dirkx	0:355018f44c9f	1301	pcb->ssthresh = pcb->cwnd / 2;
dirkx	0:355018f44c9f	1302	}
dirkx	0:355018f44c9f	1303
dirkx	0:355018f44c9f	1304	/* The minimum value for ssthresh should be 2 MSS */
dirkx	0:355018f44c9f	1305	if (pcb->ssthresh < 2*pcb->mss) {
dirkx	0:355018f44c9f	1306	LWIP_DEBUGF(TCP_FR_DEBUG,
dirkx	0:355018f44c9f	1307	("tcp_receive: The minimum value for ssthresh %"U16_F
dirkx	0:355018f44c9f	1308	" should be min 2 mss %"U16_F"...\n",
dirkx	0:355018f44c9f	1309	pcb->ssthresh, 2*pcb->mss));
dirkx	0:355018f44c9f	1310	pcb->ssthresh = 2*pcb->mss;
dirkx	0:355018f44c9f	1311	}
dirkx	0:355018f44c9f	1312
dirkx	0:355018f44c9f	1313	pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
dirkx	0:355018f44c9f	1314	pcb->flags \|= TF_INFR;
dirkx	0:355018f44c9f	1315	}
dirkx	0:355018f44c9f	1316	}
dirkx	0:355018f44c9f	1317
dirkx	0:355018f44c9f	1318
dirkx	0:355018f44c9f	1319	/**
dirkx	0:355018f44c9f	1320	* Send keepalive packets to keep a connection active although
dirkx	0:355018f44c9f	1321	* no data is sent over it.
dirkx	0:355018f44c9f	1322	*
dirkx	0:355018f44c9f	1323	* Called by tcp_slowtmr()
dirkx	0:355018f44c9f	1324	*
dirkx	0:355018f44c9f	1325	* @param pcb the tcp_pcb for which to send a keepalive packet
dirkx	0:355018f44c9f	1326	*/
dirkx	0:355018f44c9f	1327	void
dirkx	0:355018f44c9f	1328	tcp_keepalive(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	1329	{
dirkx	0:355018f44c9f	1330	struct pbuf *p;
dirkx	0:355018f44c9f	1331	struct tcp_hdr *tcphdr;
dirkx	0:355018f44c9f	1332
dirkx	0:355018f44c9f	1333	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
dirkx	0:355018f44c9f	1334	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
dirkx	0:355018f44c9f	1335	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
dirkx	0:355018f44c9f	1336
dirkx	0:355018f44c9f	1337	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
dirkx	0:355018f44c9f	1338	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
dirkx	0:355018f44c9f	1339
dirkx	0:355018f44c9f	1340	p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
dirkx	0:355018f44c9f	1341	if(p == NULL) {
dirkx	0:355018f44c9f	1342	LWIP_DEBUGF(TCP_DEBUG,
dirkx	0:355018f44c9f	1343	("tcp_keepalive: could not allocate memory for pbuf\n"));
dirkx	0:355018f44c9f	1344	return;
dirkx	0:355018f44c9f	1345	}
dirkx	0:355018f44c9f	1346	tcphdr = (struct tcp_hdr *)p->payload;
dirkx	0:355018f44c9f	1347
dirkx	0:355018f44c9f	1348	#if CHECKSUM_GEN_TCP
dirkx	0:355018f44c9f	1349	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
dirkx	0:355018f44c9f	1350	IP_PROTO_TCP, p->tot_len);
dirkx	0:355018f44c9f	1351	#endif
dirkx	0:355018f44c9f	1352	TCP_STATS_INC(tcp.xmit);
dirkx	0:355018f44c9f	1353
dirkx	0:355018f44c9f	1354	/* Send output to IP */
dirkx	0:355018f44c9f	1355	#if LWIP_NETIF_HWADDRHINT
dirkx	0:355018f44c9f	1356	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
dirkx	0:355018f44c9f	1357	&(pcb->addr_hint));
dirkx	0:355018f44c9f	1358	#else /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	1359	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
dirkx	0:355018f44c9f	1360	#endif /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	1361
dirkx	0:355018f44c9f	1362	pbuf_free(p);
dirkx	0:355018f44c9f	1363
dirkx	0:355018f44c9f	1364	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
dirkx	0:355018f44c9f	1365	pcb->snd_nxt - 1, pcb->rcv_nxt));
dirkx	0:355018f44c9f	1366	}
dirkx	0:355018f44c9f	1367
dirkx	0:355018f44c9f	1368
dirkx	0:355018f44c9f	1369	/**
dirkx	0:355018f44c9f	1370	* Send persist timer zero-window probes to keep a connection active
dirkx	0:355018f44c9f	1371	* when a window update is lost.
dirkx	0:355018f44c9f	1372	*
dirkx	0:355018f44c9f	1373	* Called by tcp_slowtmr()
dirkx	0:355018f44c9f	1374	*
dirkx	0:355018f44c9f	1375	* @param pcb the tcp_pcb for which to send a zero-window probe packet
dirkx	0:355018f44c9f	1376	*/
dirkx	0:355018f44c9f	1377	void
dirkx	0:355018f44c9f	1378	tcp_zero_window_probe(struct tcp_pcb *pcb)
dirkx	0:355018f44c9f	1379	{
dirkx	0:355018f44c9f	1380	struct pbuf *p;
dirkx	0:355018f44c9f	1381	struct tcp_hdr *tcphdr;
dirkx	0:355018f44c9f	1382	struct tcp_seg *seg;
dirkx	0:355018f44c9f	1383	u16_t len;
dirkx	0:355018f44c9f	1384	u8_t is_fin;
dirkx	0:355018f44c9f	1385
dirkx	0:355018f44c9f	1386	LWIP_DEBUGF(TCP_DEBUG,
dirkx	0:355018f44c9f	1387	("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
dirkx	0:355018f44c9f	1388	U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
dirkx	0:355018f44c9f	1389	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
dirkx	0:355018f44c9f	1390	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
dirkx	0:355018f44c9f	1391
dirkx	0:355018f44c9f	1392	LWIP_DEBUGF(TCP_DEBUG,
dirkx	0:355018f44c9f	1393	("tcp_zero_window_probe: tcp_ticks %"U32_F
dirkx	0:355018f44c9f	1394	" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
dirkx	0:355018f44c9f	1395	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
dirkx	0:355018f44c9f	1396
dirkx	0:355018f44c9f	1397	seg = pcb->unacked;
dirkx	0:355018f44c9f	1398
dirkx	0:355018f44c9f	1399	if(seg == NULL) {
dirkx	0:355018f44c9f	1400	seg = pcb->unsent;
dirkx	0:355018f44c9f	1401	}
dirkx	0:355018f44c9f	1402	if(seg == NULL) {
dirkx	0:355018f44c9f	1403	return;
dirkx	0:355018f44c9f	1404	}
dirkx	0:355018f44c9f	1405
dirkx	0:355018f44c9f	1406	is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
dirkx	0:355018f44c9f	1407	/* we want to send one seqno: either FIN or data (no options) */
dirkx	0:355018f44c9f	1408	len = is_fin ? 0 : 1;
dirkx	0:355018f44c9f	1409
dirkx	0:355018f44c9f	1410	p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
dirkx	0:355018f44c9f	1411	if(p == NULL) {
dirkx	0:355018f44c9f	1412	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
dirkx	0:355018f44c9f	1413	return;
dirkx	0:355018f44c9f	1414	}
dirkx	0:355018f44c9f	1415	tcphdr = (struct tcp_hdr *)p->payload;
dirkx	0:355018f44c9f	1416
dirkx	0:355018f44c9f	1417	if (is_fin) {
dirkx	0:355018f44c9f	1418	/* FIN segment, no data */
dirkx	0:355018f44c9f	1419	TCPH_FLAGS_SET(tcphdr, TCP_ACK \| TCP_FIN);
dirkx	0:355018f44c9f	1420	} else {
dirkx	0:355018f44c9f	1421	/* Data segment, copy in one byte from the head of the unacked queue */
dirkx	0:355018f44c9f	1422	((char )p->payload + TCP_HLEN) = (char )seg->dataptr;
dirkx	0:355018f44c9f	1423	}
dirkx	0:355018f44c9f	1424
dirkx	0:355018f44c9f	1425	#if CHECKSUM_GEN_TCP
dirkx	0:355018f44c9f	1426	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
dirkx	0:355018f44c9f	1427	IP_PROTO_TCP, p->tot_len);
dirkx	0:355018f44c9f	1428	#endif
dirkx	0:355018f44c9f	1429	TCP_STATS_INC(tcp.xmit);
dirkx	0:355018f44c9f	1430
dirkx	0:355018f44c9f	1431	/* Send output to IP */
dirkx	0:355018f44c9f	1432	#if LWIP_NETIF_HWADDRHINT
dirkx	0:355018f44c9f	1433	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
dirkx	0:355018f44c9f	1434	&(pcb->addr_hint));
dirkx	0:355018f44c9f	1435	#else /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	1436	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
dirkx	0:355018f44c9f	1437	#endif /* LWIP_NETIF_HWADDRHINT*/
dirkx	0:355018f44c9f	1438
dirkx	0:355018f44c9f	1439	pbuf_free(p);
dirkx	0:355018f44c9f	1440
dirkx	0:355018f44c9f	1441	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
dirkx	0:355018f44c9f	1442	" ackno %"U32_F".\n",
dirkx	0:355018f44c9f	1443	pcb->snd_nxt - 1, pcb->rcv_nxt));
dirkx	0:355018f44c9f	1444	}
dirkx	0:355018f44c9f	1445	#endif /* LWIP_TCP */

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Type:	Library
Created:	21 Dec 2012
Imports:	1
Forks:	0
Commits:	9
Dependents:	1
Dependencies:	0
Followers:	2

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lwip/core/tcp_out.cpp@8:275256b5d807, 2014-10-16 (annotated)

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