Bonjour - First step: AutoIP compiled in and working

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Darran Shepherd / Mbed 2 deprecated Bonjour

First step: AutoIP compiled in and working

lwip/core/tcp_out.c@1:4218cacaf696, 2010-06-18 (annotated)

Committer:: darran
Date:: Fri Jun 18 15:54:21 2010 +0000
Revision:: 1:4218cacaf696
Parent:: 0:55a05330f8cc

Who changed what in which revision?

User	Revision	Line number	New contents of line
darran	0:55a05330f8cc	1	/**
darran	0:55a05330f8cc	2	* @file
darran	0:55a05330f8cc	3	* Transmission Control Protocol, outgoing traffic
darran	0:55a05330f8cc	4	*
darran	0:55a05330f8cc	5	* The output functions of TCP.
darran	0:55a05330f8cc	6	*
darran	0:55a05330f8cc	7	*/
darran	0:55a05330f8cc	8
darran	0:55a05330f8cc	9	/*
darran	0:55a05330f8cc	10	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
darran	0:55a05330f8cc	11	* All rights reserved.
darran	0:55a05330f8cc	12	*
darran	0:55a05330f8cc	13	* Redistribution and use in source and binary forms, with or without modification,
darran	0:55a05330f8cc	14	* are permitted provided that the following conditions are met:
darran	0:55a05330f8cc	15	*
darran	0:55a05330f8cc	16	* 1. Redistributions of source code must retain the above copyright notice,
darran	0:55a05330f8cc	17	* this list of conditions and the following disclaimer.
darran	0:55a05330f8cc	18	* 2. Redistributions in binary form must reproduce the above copyright notice,
darran	0:55a05330f8cc	19	* this list of conditions and the following disclaimer in the documentation
darran	0:55a05330f8cc	20	* and/or other materials provided with the distribution.
darran	0:55a05330f8cc	21	* 3. The name of the author may not be used to endorse or promote products
darran	0:55a05330f8cc	22	* derived from this software without specific prior written permission.
darran	0:55a05330f8cc	23	*
darran	0:55a05330f8cc	24	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
darran	0:55a05330f8cc	25	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
darran	0:55a05330f8cc	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
darran	0:55a05330f8cc	27	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
darran	0:55a05330f8cc	28	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
darran	0:55a05330f8cc	29	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
darran	0:55a05330f8cc	30	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
darran	0:55a05330f8cc	31	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
darran	0:55a05330f8cc	32	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
darran	0:55a05330f8cc	33	* OF SUCH DAMAGE.
darran	0:55a05330f8cc	34	*
darran	0:55a05330f8cc	35	* This file is part of the lwIP TCP/IP stack.
darran	0:55a05330f8cc	36	*
darran	0:55a05330f8cc	37	* Author: Adam Dunkels <adam@sics.se>
darran	0:55a05330f8cc	38	*
darran	0:55a05330f8cc	39	*/
darran	0:55a05330f8cc	40
darran	0:55a05330f8cc	41	#include "lwip/opt.h"
darran	0:55a05330f8cc	42
darran	0:55a05330f8cc	43	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
darran	0:55a05330f8cc	44
darran	0:55a05330f8cc	45	#include "lwip/tcp_impl.h"
darran	0:55a05330f8cc	46	#include "lwip/def.h"
darran	0:55a05330f8cc	47	#include "lwip/mem.h"
darran	0:55a05330f8cc	48	#include "lwip/memp.h"
darran	0:55a05330f8cc	49	#include "lwip/sys.h"
darran	0:55a05330f8cc	50	#include "lwip/ip_addr.h"
darran	0:55a05330f8cc	51	#include "lwip/netif.h"
darran	0:55a05330f8cc	52	#include "lwip/inet_chksum.h"
darran	0:55a05330f8cc	53	#include "lwip/stats.h"
darran	0:55a05330f8cc	54	#include "lwip/snmp.h"
darran	0:55a05330f8cc	55
darran	0:55a05330f8cc	56	#include <string.h>
darran	0:55a05330f8cc	57
darran	0:55a05330f8cc	58	/* Define some copy-macros for checksum-on-copy so that the code looks
darran	0:55a05330f8cc	59	nicer by preventing too many ifdef's. */
darran	0:55a05330f8cc	60	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	61	#define TCP_DATA_COPY(dst, src, len, seg) do { \
darran	0:55a05330f8cc	62	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
darran	0:55a05330f8cc	63	len, &seg->chksum, &seg->chksum_swapped); \
darran	0:55a05330f8cc	64	seg->flags \|= TF_SEG_DATA_CHECKSUMMED; } while(0)
darran	0:55a05330f8cc	65	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
darran	0:55a05330f8cc	66	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
darran	0:55a05330f8cc	67	#else /* TCP_CHECKSUM_ON_COPY*/
darran	0:55a05330f8cc	68	#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
darran	0:55a05330f8cc	69	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
darran	0:55a05330f8cc	70	#endif /* TCP_CHECKSUM_ON_COPY*/
darran	0:55a05330f8cc	71
darran	0:55a05330f8cc	72	/** Define this to 1 for an extra check that the output checksum is valid
darran	0:55a05330f8cc	73	* (usefule when the checksum is generated by the application, not the stack) */
darran	0:55a05330f8cc	74	#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
darran	0:55a05330f8cc	75	#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
darran	0:55a05330f8cc	76	#endif
darran	0:55a05330f8cc	77
darran	0:55a05330f8cc	78	/* Forward declarations.*/
darran	0:55a05330f8cc	79	static void tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb);
darran	0:55a05330f8cc	80
darran	0:55a05330f8cc	81	/** Allocate a pbuf and create a tcphdr at p->payload, used for output
darran	0:55a05330f8cc	82	* functions other than the default tcp_output -> tcp_output_segment
darran	0:55a05330f8cc	83	* (e.g. tcp_send_empty_ack, etc.)
darran	0:55a05330f8cc	84	*
darran	0:55a05330f8cc	85	* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
darran	0:55a05330f8cc	86	* @param optlen length of header-options
darran	0:55a05330f8cc	87	* @param datalen length of tcp data to reserve in pbuf
darran	0:55a05330f8cc	88	* @param seqno_be seqno in network byte order (big-endian)
darran	0:55a05330f8cc	89	* @return pbuf with p->payload being the tcp_hdr
darran	0:55a05330f8cc	90	*/
darran	0:55a05330f8cc	91	static struct pbuf *
darran	0:55a05330f8cc	92	tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
darran	0:55a05330f8cc	93	u32_t seqno_be /* already in network byte order */)
darran	0:55a05330f8cc	94	{
darran	0:55a05330f8cc	95	struct tcp_hdr *tcphdr;
darran	0:55a05330f8cc	96	struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
darran	0:55a05330f8cc	97	if (p != NULL) {
darran	0:55a05330f8cc	98	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
darran	0:55a05330f8cc	99	(p->len >= TCP_HLEN + optlen));
darran	0:55a05330f8cc	100	tcphdr = (struct tcp_hdr *)p->payload;
darran	0:55a05330f8cc	101	tcphdr->src = htons(pcb->local_port);
darran	0:55a05330f8cc	102	tcphdr->dest = htons(pcb->remote_port);
darran	0:55a05330f8cc	103	tcphdr->seqno = seqno_be;
darran	0:55a05330f8cc	104	tcphdr->ackno = htonl(pcb->rcv_nxt);
darran	0:55a05330f8cc	105	TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
darran	0:55a05330f8cc	106	tcphdr->wnd = htons(pcb->rcv_ann_wnd);
darran	0:55a05330f8cc	107	tcphdr->chksum = 0;
darran	0:55a05330f8cc	108	tcphdr->urgp = 0;
darran	0:55a05330f8cc	109
darran	0:55a05330f8cc	110	/* If we're sending a packet, update the announced right window edge */
darran	0:55a05330f8cc	111	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
darran	0:55a05330f8cc	112	}
darran	0:55a05330f8cc	113	return p;
darran	0:55a05330f8cc	114	}
darran	0:55a05330f8cc	115
darran	0:55a05330f8cc	116	/**
darran	0:55a05330f8cc	117	* Called by tcp_close() to send a segment including FIN flag but not data.
darran	0:55a05330f8cc	118	*
darran	0:55a05330f8cc	119	* @param pcb the tcp_pcb over which to send a segment
darran	0:55a05330f8cc	120	* @return ERR_OK if sent, another err_t otherwise
darran	0:55a05330f8cc	121	*/
darran	0:55a05330f8cc	122	err_t
darran	0:55a05330f8cc	123	tcp_send_fin(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	124	{
darran	0:55a05330f8cc	125	/* first, try to add the fin to the last unsent segment */
darran	0:55a05330f8cc	126	if (pcb->unsent != NULL) {
darran	0:55a05330f8cc	127	struct tcp_seg *last_unsent;
darran	0:55a05330f8cc	128	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
darran	0:55a05330f8cc	129	last_unsent = last_unsent->next);
darran	0:55a05330f8cc	130
darran	0:55a05330f8cc	131	if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN \| TCP_FIN \| TCP_RST)) == 0) {
darran	0:55a05330f8cc	132	/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
darran	0:55a05330f8cc	133	TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
darran	0:55a05330f8cc	134	return ERR_OK;
darran	0:55a05330f8cc	135	}
darran	0:55a05330f8cc	136	}
darran	0:55a05330f8cc	137	/* no data, no length, flags, copy=1, no optdata */
darran	0:55a05330f8cc	138	return tcp_enqueue_flags(pcb, TCP_FIN);
darran	0:55a05330f8cc	139	}
darran	0:55a05330f8cc	140
darran	0:55a05330f8cc	141	/**
darran	0:55a05330f8cc	142	* Create a TCP segment with prefilled header.
darran	0:55a05330f8cc	143	*
darran	0:55a05330f8cc	144	* Called by tcp_write and tcp_enqueue_flags.
darran	0:55a05330f8cc	145	*
darran	0:55a05330f8cc	146	* @param pcb Protocol control block for the TCP connection.
darran	0:55a05330f8cc	147	* @param p pbuf that is used to hold the TCP header.
darran	0:55a05330f8cc	148	* @param flags TCP flags for header.
darran	0:55a05330f8cc	149	* @param seqno TCP sequence number of this packet
darran	0:55a05330f8cc	150	* @param optflags options to include in TCP header
darran	0:55a05330f8cc	151	* @return a new tcp_seg pointing to p, or NULL.
darran	0:55a05330f8cc	152	* The TCP header is filled in except ackno and wnd.
darran	0:55a05330f8cc	153	* p is freed on failure.
darran	0:55a05330f8cc	154	*/
darran	0:55a05330f8cc	155	static struct tcp_seg *
darran	0:55a05330f8cc	156	tcp_create_segment(struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
darran	0:55a05330f8cc	157	{
darran	0:55a05330f8cc	158	struct tcp_seg *seg;
darran	0:55a05330f8cc	159	u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
darran	0:55a05330f8cc	160
darran	0:55a05330f8cc	161	if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
darran	0:55a05330f8cc	162	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no memory.\n"));
darran	0:55a05330f8cc	163	pbuf_free(p);
darran	0:55a05330f8cc	164	return NULL;
darran	0:55a05330f8cc	165	}
darran	0:55a05330f8cc	166	seg->flags = optflags;
darran	0:55a05330f8cc	167	seg->next = NULL;
darran	0:55a05330f8cc	168	seg->p = p;
darran	0:55a05330f8cc	169	seg->dataptr = p->payload;
darran	0:55a05330f8cc	170	seg->len = p->tot_len - optlen;
darran	0:55a05330f8cc	171	#if TCP_OVERSIZE_DBGCHECK
darran	0:55a05330f8cc	172	seg->oversize_left = 0;
darran	0:55a05330f8cc	173	#endif /* TCP_OVERSIZE_DBGCHECK */
darran	0:55a05330f8cc	174	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	175	seg->chksum = 0;
darran	0:55a05330f8cc	176	seg->chksum_swapped = 0;
darran	0:55a05330f8cc	177	/* check optflags */
darran	0:55a05330f8cc	178	LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
darran	0:55a05330f8cc	179	(optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
darran	0:55a05330f8cc	180	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	181
darran	0:55a05330f8cc	182	/* build TCP header */
darran	0:55a05330f8cc	183	if (pbuf_header(p, TCP_HLEN)) {
darran	0:55a05330f8cc	184	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
darran	0:55a05330f8cc	185	TCP_STATS_INC(tcp.err);
darran	0:55a05330f8cc	186	tcp_seg_free(seg);
darran	0:55a05330f8cc	187	return NULL;
darran	0:55a05330f8cc	188	}
darran	0:55a05330f8cc	189	seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
darran	0:55a05330f8cc	190	seg->tcphdr->src = htons(pcb->local_port);
darran	0:55a05330f8cc	191	seg->tcphdr->dest = htons(pcb->remote_port);
darran	0:55a05330f8cc	192	seg->tcphdr->seqno = htonl(seqno);
darran	0:55a05330f8cc	193	/* ackno is set in tcp_output */
darran	0:55a05330f8cc	194	TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
darran	0:55a05330f8cc	195	/* wnd and chksum are set in tcp_output */
darran	0:55a05330f8cc	196	seg->tcphdr->urgp = 0;
darran	0:55a05330f8cc	197	return seg;
darran	0:55a05330f8cc	198	}
darran	0:55a05330f8cc	199
darran	0:55a05330f8cc	200	/**
darran	0:55a05330f8cc	201	* Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
darran	0:55a05330f8cc	202	*
darran	0:55a05330f8cc	203	* This function is like pbuf_alloc(layer, length, PBUF_RAM) except
darran	0:55a05330f8cc	204	* there may be extra bytes available at the end.
darran	0:55a05330f8cc	205	*
darran	0:55a05330f8cc	206	* @param layer flag to define header size.
darran	0:55a05330f8cc	207	* @param length size of the pbuf's payload.
darran	0:55a05330f8cc	208	* @param max_length maximum usable size of payload+oversize.
darran	0:55a05330f8cc	209	* @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
darran	0:55a05330f8cc	210	* @param pcb The TCP connection that willo enqueue the pbuf.
darran	0:55a05330f8cc	211	* @param apiflags API flags given to tcp_write.
darran	0:55a05330f8cc	212	* @param first_seg true when this pbuf will be used in the first enqueued segment.
darran	0:55a05330f8cc	213	* @param
darran	0:55a05330f8cc	214	*/
darran	0:55a05330f8cc	215	#if TCP_OVERSIZE
darran	0:55a05330f8cc	216	static struct pbuf *
darran	0:55a05330f8cc	217	tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
darran	0:55a05330f8cc	218	u16_t oversize, struct tcp_pcb pcb, u8_t apiflags,
darran	0:55a05330f8cc	219	u8_t first_seg)
darran	0:55a05330f8cc	220	{
darran	0:55a05330f8cc	221	struct pbuf *p;
darran	0:55a05330f8cc	222	u16_t alloc = length;
darran	0:55a05330f8cc	223
darran	0:55a05330f8cc	224	if (length < max_length) {
darran	0:55a05330f8cc	225	/* Should we allocate an oversized pbuf, or just the minimum
darran	0:55a05330f8cc	226	* length required? If tcp_write is going to be called again
darran	0:55a05330f8cc	227	* before this segment is transmitted, we want the oversized
darran	0:55a05330f8cc	228	* buffer. If the segment will be transmitted immediately, we can
darran	0:55a05330f8cc	229	* save memory by allocating only length. We use a simple
darran	0:55a05330f8cc	230	* heuristic based on the following information:
darran	0:55a05330f8cc	231	*
darran	0:55a05330f8cc	232	* Did the user set TCP_WRITE_FLAG_MORE?
darran	0:55a05330f8cc	233	*
darran	0:55a05330f8cc	234	* Will the Nagle algorithm defer transmission of this segment?
darran	0:55a05330f8cc	235	*/
darran	0:55a05330f8cc	236	if ((apiflags & TCP_WRITE_FLAG_MORE) \|\|
darran	0:55a05330f8cc	237	(!(pcb->flags & TF_NODELAY) &&
darran	0:55a05330f8cc	238	(!first_seg \|\|
darran	0:55a05330f8cc	239	pcb->unsent != NULL \|\|
darran	0:55a05330f8cc	240	pcb->unacked != NULL))) {
darran	0:55a05330f8cc	241	alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
darran	0:55a05330f8cc	242	}
darran	0:55a05330f8cc	243	}
darran	0:55a05330f8cc	244	p = pbuf_alloc(layer, alloc, PBUF_RAM);
darran	0:55a05330f8cc	245	if (p == NULL) {
darran	0:55a05330f8cc	246	return NULL;
darran	0:55a05330f8cc	247	}
darran	0:55a05330f8cc	248	LWIP_ASSERT("need unchained pbuf", p->next == NULL);
darran	0:55a05330f8cc	249	*oversize = p->len - length;
darran	0:55a05330f8cc	250	/* trim p->len to the currently used size */
darran	0:55a05330f8cc	251	p->len = p->tot_len = length;
darran	0:55a05330f8cc	252	return p;
darran	0:55a05330f8cc	253	}
darran	0:55a05330f8cc	254	#else /* TCP_OVERSIZE */
darran	0:55a05330f8cc	255	#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
darran	0:55a05330f8cc	256	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	257
darran	0:55a05330f8cc	258	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	259	/** Add a checksum of newly added data to the segment */
darran	0:55a05330f8cc	260	static void
darran	0:55a05330f8cc	261	tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
darran	0:55a05330f8cc	262	u8_t *seg_chksum_swapped)
darran	0:55a05330f8cc	263	{
darran	0:55a05330f8cc	264	u32_t helper;
darran	0:55a05330f8cc	265	/* add chksum to old chksum and fold to u16_t */
darran	0:55a05330f8cc	266	helper = chksum + *seg_chksum;
darran	0:55a05330f8cc	267	chksum = FOLD_U32T(helper);
darran	0:55a05330f8cc	268	if ((len & 1) != 0) {
darran	0:55a05330f8cc	269	seg_chksum_swapped = 1 - seg_chksum_swapped;
darran	0:55a05330f8cc	270	chksum = SWAP_BYTES_IN_WORD(chksum);
darran	0:55a05330f8cc	271	}
darran	0:55a05330f8cc	272	*seg_chksum = chksum;
darran	0:55a05330f8cc	273	}
darran	0:55a05330f8cc	274	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	275
darran	0:55a05330f8cc	276	/**
darran	0:55a05330f8cc	277	* Write data for sending (but does not send it immediately).
darran	0:55a05330f8cc	278	*
darran	0:55a05330f8cc	279	* It waits in the expectation of more data being sent soon (as
darran	0:55a05330f8cc	280	* it can send them more efficiently by combining them together).
darran	0:55a05330f8cc	281	* To prompt the system to send data now, call tcp_output() after
darran	0:55a05330f8cc	282	* calling tcp_write().
darran	0:55a05330f8cc	283	*
darran	0:55a05330f8cc	284	* @param pcb Protocol control block for the TCP connection to enqueue data for.
darran	0:55a05330f8cc	285	* @param arg Pointer to the data to be enqueued for sending.
darran	0:55a05330f8cc	286	* @param len Data length in bytes
darran	0:55a05330f8cc	287	* @param apiflags combination of following flags :
darran	0:55a05330f8cc	288	* - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
darran	0:55a05330f8cc	289	* - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
darran	0:55a05330f8cc	290	* @return ERR_OK if enqueued, another err_t on error
darran	0:55a05330f8cc	291	*/
darran	0:55a05330f8cc	292	err_t
darran	0:55a05330f8cc	293	tcp_write(struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
darran	0:55a05330f8cc	294	{
darran	0:55a05330f8cc	295	struct pbuf *concat_p = NULL;
darran	0:55a05330f8cc	296	struct tcp_seg last_unsent = NULL, seg = NULL, prev_seg = NULL, queue = NULL;
darran	0:55a05330f8cc	297	u16_t pos = 0; /* position in 'arg' data */
darran	0:55a05330f8cc	298	u16_t queuelen;
darran	0:55a05330f8cc	299	u8_t optlen = 0;
darran	0:55a05330f8cc	300	u8_t optflags = 0;
darran	0:55a05330f8cc	301	#if TCP_OVERSIZE
darran	0:55a05330f8cc	302	u16_t oversize = 0;
darran	0:55a05330f8cc	303	u16_t oversize_used = 0;
darran	0:55a05330f8cc	304	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	305	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	306	u16_t concat_chksum = 0;
darran	0:55a05330f8cc	307	u8_t concat_chksum_swapped = 0;
darran	0:55a05330f8cc	308	u16_t concat_chksummed = 0;
darran	0:55a05330f8cc	309	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	310
darran	0:55a05330f8cc	311	#if LWIP_NETIF_TX_SINGLE_PBUF
darran	0:55a05330f8cc	312	/* Always copy to try to create single pbufs for TX */
darran	0:55a05330f8cc	313	apiflags \|= TCP_WRITE_FLAG_COPY;
darran	0:55a05330f8cc	314	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
darran	0:55a05330f8cc	315
darran	0:55a05330f8cc	316	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
darran	0:55a05330f8cc	317	(void *)pcb, arg, len, (u16_t)apiflags));
darran	0:55a05330f8cc	318	/* connection is in invalid state for data transmission? */
darran	0:55a05330f8cc	319	if ((pcb->state != ESTABLISHED) &&
darran	0:55a05330f8cc	320	(pcb->state != CLOSE_WAIT) &&
darran	0:55a05330f8cc	321	(pcb->state != SYN_SENT) &&
darran	0:55a05330f8cc	322	(pcb->state != SYN_RCVD)) {
darran	0:55a05330f8cc	323	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_STATE \| LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
darran	0:55a05330f8cc	324	return ERR_CONN;
darran	0:55a05330f8cc	325	} else if (len == 0) {
darran	0:55a05330f8cc	326	return ERR_OK;
darran	0:55a05330f8cc	327	}
darran	0:55a05330f8cc	328
darran	0:55a05330f8cc	329	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, arg=%p, len=%"U16_F", apiflags=%"U16_F")\n",
darran	0:55a05330f8cc	330	(void *)pcb, arg, len, (u16_t)apiflags));
darran	0:55a05330f8cc	331	LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
darran	0:55a05330f8cc	332	arg != NULL, return ERR_ARG;);
darran	0:55a05330f8cc	333
darran	0:55a05330f8cc	334	/* fail on too much data */
darran	0:55a05330f8cc	335	if (len > pcb->snd_buf) {
darran	0:55a05330f8cc	336	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
darran	0:55a05330f8cc	337	len, pcb->snd_buf));
darran	0:55a05330f8cc	338	pcb->flags \|= TF_NAGLEMEMERR;
darran	0:55a05330f8cc	339	return ERR_MEM;
darran	0:55a05330f8cc	340	}
darran	0:55a05330f8cc	341
darran	0:55a05330f8cc	342	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
darran	0:55a05330f8cc	343
darran	0:55a05330f8cc	344	/* If total number of pbufs on the unsent/unacked queues exceeds the
darran	0:55a05330f8cc	345	* configured maximum, return an error */
darran	0:55a05330f8cc	346	queuelen = pcb->snd_queuelen;
darran	0:55a05330f8cc	347	/* check for configured max queuelen and possible overflow */
darran	0:55a05330f8cc	348	if ((queuelen >= TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
darran	0:55a05330f8cc	349	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
darran	0:55a05330f8cc	350	queuelen, TCP_SND_QUEUELEN));
darran	0:55a05330f8cc	351	TCP_STATS_INC(tcp.memerr);
darran	0:55a05330f8cc	352	pcb->flags \|= TF_NAGLEMEMERR;
darran	0:55a05330f8cc	353	return ERR_MEM;
darran	0:55a05330f8cc	354	}
darran	0:55a05330f8cc	355	if (queuelen != 0) {
darran	0:55a05330f8cc	356	LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
darran	0:55a05330f8cc	357	pcb->unacked != NULL \|\| pcb->unsent != NULL);
darran	0:55a05330f8cc	358	} else {
darran	0:55a05330f8cc	359	LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
darran	0:55a05330f8cc	360	pcb->unacked == NULL && pcb->unsent == NULL);
darran	0:55a05330f8cc	361	}
darran	0:55a05330f8cc	362
darran	0:55a05330f8cc	363	#if LWIP_TCP_TIMESTAMPS
darran	0:55a05330f8cc	364	if ((pcb->flags & TF_TIMESTAMP)) {
darran	0:55a05330f8cc	365	optflags = TF_SEG_OPTS_TS;
darran	0:55a05330f8cc	366	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
darran	0:55a05330f8cc	367	}
darran	0:55a05330f8cc	368	#endif /* LWIP_TCP_TIMESTAMPS */
darran	0:55a05330f8cc	369
darran	0:55a05330f8cc	370
darran	0:55a05330f8cc	371	/*
darran	0:55a05330f8cc	372	* TCP segmentation is done in three phases with increasing complexity:
darran	0:55a05330f8cc	373	*
darran	0:55a05330f8cc	374	* 1. Copy data directly into an oversized pbuf.
darran	0:55a05330f8cc	375	* 2. Chain a new pbuf to the end of pcb->unsent.
darran	0:55a05330f8cc	376	* 3. Create new segments.
darran	0:55a05330f8cc	377	*
darran	0:55a05330f8cc	378	* We may run out of memory at any point. In that case we must
darran	0:55a05330f8cc	379	* return ERR_MEM and not change anything in pcb. Therefore, all
darran	0:55a05330f8cc	380	* changes are recorded in local variables and committed at the end
darran	0:55a05330f8cc	381	* of the function. Some pcb fields are maintained in local copies:
darran	0:55a05330f8cc	382	*
darran	0:55a05330f8cc	383	* queuelen = pcb->snd_queuelen
darran	0:55a05330f8cc	384	* oversize = pcb->unsent_oversize
darran	0:55a05330f8cc	385	*
darran	0:55a05330f8cc	386	* These variables are set consistently by the phases:
darran	0:55a05330f8cc	387	*
darran	0:55a05330f8cc	388	* seg points to the last segment tampered with.
darran	0:55a05330f8cc	389	*
darran	0:55a05330f8cc	390	* pos records progress as data is segmented.
darran	0:55a05330f8cc	391	*/
darran	0:55a05330f8cc	392
darran	0:55a05330f8cc	393	/* Find the tail of the unsent queue. */
darran	0:55a05330f8cc	394	if (pcb->unsent != NULL) {
darran	0:55a05330f8cc	395	u16_t space;
darran	0:55a05330f8cc	396	u16_t unsent_optlen;
darran	0:55a05330f8cc	397
darran	0:55a05330f8cc	398	/* @todo: this could be sped up by keeping last_unsent in the pcb */
darran	0:55a05330f8cc	399	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
darran	0:55a05330f8cc	400	last_unsent = last_unsent->next);
darran	0:55a05330f8cc	401
darran	0:55a05330f8cc	402	/* Usable space at the end of the last unsent segment */
darran	0:55a05330f8cc	403	unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
darran	0:55a05330f8cc	404	space = pcb->mss - (last_unsent->len + unsent_optlen);
darran	0:55a05330f8cc	405
darran	0:55a05330f8cc	406	/*
darran	0:55a05330f8cc	407	* Phase 1: Copy data directly into an oversized pbuf.
darran	0:55a05330f8cc	408	*
darran	0:55a05330f8cc	409	* The number of bytes copied is recorded in the oversize_used
darran	0:55a05330f8cc	410	* variable. The actual copying is done at the bottom of the
darran	0:55a05330f8cc	411	* function.
darran	0:55a05330f8cc	412	*/
darran	0:55a05330f8cc	413	#if TCP_OVERSIZE
darran	0:55a05330f8cc	414	#if TCP_OVERSIZE_DBGCHECK
darran	0:55a05330f8cc	415	/* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
darran	0:55a05330f8cc	416	LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
darran	0:55a05330f8cc	417	pcb->unsent_oversize == last_unsent->oversize_left);
darran	0:55a05330f8cc	418	#endif /* TCP_OVERSIZE_DBGCHECK */
darran	0:55a05330f8cc	419	oversize = pcb->unsent_oversize;
darran	0:55a05330f8cc	420	if (oversize > 0) {
darran	0:55a05330f8cc	421	LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
darran	0:55a05330f8cc	422	seg = last_unsent;
darran	0:55a05330f8cc	423	oversize_used = oversize < len ? oversize : len;
darran	0:55a05330f8cc	424	pos += oversize_used;
darran	0:55a05330f8cc	425	oversize -= oversize_used;
darran	0:55a05330f8cc	426	space -= oversize_used;
darran	0:55a05330f8cc	427	}
darran	0:55a05330f8cc	428	/* now we are either finished or oversize is zero */
darran	0:55a05330f8cc	429	LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) \|\| (pos == len));
darran	0:55a05330f8cc	430	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	431
darran	0:55a05330f8cc	432	/*
darran	0:55a05330f8cc	433	* Phase 2: Chain a new pbuf to the end of pcb->unsent.
darran	0:55a05330f8cc	434	*
darran	0:55a05330f8cc	435	* We don't extend segments containing SYN/FIN flags or options
darran	0:55a05330f8cc	436	* (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
darran	0:55a05330f8cc	437	* the end.
darran	0:55a05330f8cc	438	*/
darran	0:55a05330f8cc	439	if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
darran	0:55a05330f8cc	440	u16_t seglen = space < len - pos ? space : len - pos;
darran	0:55a05330f8cc	441	seg = last_unsent;
darran	0:55a05330f8cc	442
darran	0:55a05330f8cc	443	/* Create a pbuf with a copy or reference to seglen bytes. We
darran	0:55a05330f8cc	444	* can use PBUF_RAW here since the data appears in the middle of
darran	0:55a05330f8cc	445	* a segment. A header will never be prepended. */
darran	0:55a05330f8cc	446	if (apiflags & TCP_WRITE_FLAG_COPY) {
darran	0:55a05330f8cc	447	/* Data is copied */
darran	0:55a05330f8cc	448	if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
darran	0:55a05330f8cc	449	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
darran	0:55a05330f8cc	450	("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
darran	0:55a05330f8cc	451	seglen));
darran	0:55a05330f8cc	452	goto memerr;
darran	0:55a05330f8cc	453	}
darran	0:55a05330f8cc	454	#if TCP_OVERSIZE_DBGCHECK
darran	0:55a05330f8cc	455	last_unsent->oversize_left = oversize;
darran	0:55a05330f8cc	456	#endif /* TCP_OVERSIZE_DBGCHECK */
darran	0:55a05330f8cc	457	TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
darran	0:55a05330f8cc	458	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	459	concat_chksummed += seglen;
darran	0:55a05330f8cc	460	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	461	} else {
darran	0:55a05330f8cc	462	/* Data is not copied */
darran	0:55a05330f8cc	463	if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
darran	0:55a05330f8cc	464	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
darran	0:55a05330f8cc	465	("tcp_write: could not allocate memory for zero-copy pbuf\n"));
darran	0:55a05330f8cc	466	goto memerr;
darran	0:55a05330f8cc	467	}
darran	0:55a05330f8cc	468	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	469	/* calculate the checksum of nocopy-data */
darran	0:55a05330f8cc	470	tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
darran	0:55a05330f8cc	471	&concat_chksum, &concat_chksum_swapped);
darran	0:55a05330f8cc	472	concat_chksummed += seglen;
darran	0:55a05330f8cc	473	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	474	/* reference the non-volatile payload data */
darran	0:55a05330f8cc	475	concat_p->payload = (u8_t*)arg + pos;
darran	0:55a05330f8cc	476	}
darran	0:55a05330f8cc	477
darran	0:55a05330f8cc	478	pos += seglen;
darran	0:55a05330f8cc	479	queuelen += pbuf_clen(concat_p);
darran	0:55a05330f8cc	480	}
darran	0:55a05330f8cc	481	} else {
darran	0:55a05330f8cc	482	#if TCP_OVERSIZE
darran	0:55a05330f8cc	483	LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
darran	0:55a05330f8cc	484	pcb->unsent_oversize == 0);
darran	0:55a05330f8cc	485	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	486	}
darran	0:55a05330f8cc	487
darran	0:55a05330f8cc	488	/*
darran	0:55a05330f8cc	489	* Phase 3: Create new segments.
darran	0:55a05330f8cc	490	*
darran	0:55a05330f8cc	491	* The new segments are chained together in the local 'queue'
darran	0:55a05330f8cc	492	* variable, ready to be appended to pcb->unsent.
darran	0:55a05330f8cc	493	*/
darran	0:55a05330f8cc	494	while (pos < len) {
darran	0:55a05330f8cc	495	struct pbuf *p;
darran	0:55a05330f8cc	496	u16_t left = len - pos;
darran	0:55a05330f8cc	497	u16_t max_len = pcb->mss - optlen;
darran	0:55a05330f8cc	498	u16_t seglen = left > max_len ? max_len : left;
darran	0:55a05330f8cc	499	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	500	u16_t chksum = 0;
darran	0:55a05330f8cc	501	u8_t chksum_swapped = 0;
darran	0:55a05330f8cc	502	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	503
darran	0:55a05330f8cc	504	if (apiflags & TCP_WRITE_FLAG_COPY) {
darran	0:55a05330f8cc	505	/* If copy is set, memory should be allocated and data copied
darran	0:55a05330f8cc	506	* into pbuf */
darran	0:55a05330f8cc	507	if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, pcb->mss, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
darran	0:55a05330f8cc	508	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
darran	0:55a05330f8cc	509	goto memerr;
darran	0:55a05330f8cc	510	}
darran	0:55a05330f8cc	511	LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
darran	0:55a05330f8cc	512	(p->len >= seglen));
darran	0:55a05330f8cc	513	TCP_DATA_COPY2((char )p->payload + optlen, (u8_t)arg + pos, seglen, &chksum, &chksum_swapped);
darran	0:55a05330f8cc	514	} else {
darran	0:55a05330f8cc	515	/* Copy is not set: First allocate a pbuf for holding the data.
darran	0:55a05330f8cc	516	* Since the referenced data is available at least until it is
darran	0:55a05330f8cc	517	* sent out on the link (as it has to be ACKed by the remote
darran	0:55a05330f8cc	518	* party) we can safely use PBUF_ROM instead of PBUF_REF here.
darran	0:55a05330f8cc	519	*/
darran	0:55a05330f8cc	520	struct pbuf *p2;
darran	0:55a05330f8cc	521	#if TCP_OVERSIZE
darran	0:55a05330f8cc	522	LWIP_ASSERT("oversize == 0", oversize == 0);
darran	0:55a05330f8cc	523	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	524	if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
darran	0:55a05330f8cc	525	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
darran	0:55a05330f8cc	526	goto memerr;
darran	0:55a05330f8cc	527	}
darran	0:55a05330f8cc	528	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	529	/* calculate the checksum of nocopy-data */
darran	0:55a05330f8cc	530	chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
darran	0:55a05330f8cc	531	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	532	/* reference the non-volatile payload data */
darran	0:55a05330f8cc	533	p2->payload = (u8_t*)arg + pos;
darran	0:55a05330f8cc	534
darran	0:55a05330f8cc	535	/* Second, allocate a pbuf for the headers. */
darran	0:55a05330f8cc	536	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
darran	0:55a05330f8cc	537	/* If allocation fails, we have to deallocate the data pbuf as
darran	0:55a05330f8cc	538	* well. */
darran	0:55a05330f8cc	539	pbuf_free(p2);
darran	0:55a05330f8cc	540	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for header pbuf\n"));
darran	0:55a05330f8cc	541	goto memerr;
darran	0:55a05330f8cc	542	}
darran	0:55a05330f8cc	543	/* Concatenate the headers and data pbufs together. */
darran	0:55a05330f8cc	544	pbuf_cat(p/header/, p2/data/);
darran	0:55a05330f8cc	545	}
darran	0:55a05330f8cc	546
darran	0:55a05330f8cc	547	queuelen += pbuf_clen(p);
darran	0:55a05330f8cc	548
darran	0:55a05330f8cc	549	/* Now that there are more segments queued, we check again if the
darran	0:55a05330f8cc	550	* length of the queue exceeds the configured maximum or
darran	0:55a05330f8cc	551	* overflows. */
darran	0:55a05330f8cc	552	if ((queuelen > TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
darran	0:55a05330f8cc	553	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
darran	0:55a05330f8cc	554	pbuf_free(p);
darran	0:55a05330f8cc	555	goto memerr;
darran	0:55a05330f8cc	556	}
darran	0:55a05330f8cc	557
darran	0:55a05330f8cc	558	if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
darran	0:55a05330f8cc	559	goto memerr;
darran	0:55a05330f8cc	560	}
darran	0:55a05330f8cc	561	#if TCP_OVERSIZE_DBGCHECK
darran	0:55a05330f8cc	562	seg->oversize_left = oversize;
darran	0:55a05330f8cc	563	#endif /* TCP_OVERSIZE_DBGCHECK */
darran	0:55a05330f8cc	564	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	565	seg->chksum = chksum;
darran	0:55a05330f8cc	566	seg->chksum_swapped = chksum_swapped;
darran	0:55a05330f8cc	567	seg->flags \|= TF_SEG_DATA_CHECKSUMMED;
darran	0:55a05330f8cc	568	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	569	/* Fix dataptr for the nocopy case */
darran	0:55a05330f8cc	570	if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
darran	0:55a05330f8cc	571	seg->dataptr = (u8_t*)arg + pos;
darran	0:55a05330f8cc	572	}
darran	0:55a05330f8cc	573
darran	0:55a05330f8cc	574	/* first segment of to-be-queued data? */
darran	0:55a05330f8cc	575	if (queue == NULL) {
darran	0:55a05330f8cc	576	queue = seg;
darran	0:55a05330f8cc	577	} else {
darran	0:55a05330f8cc	578	/* Attach the segment to the end of the queued segments */
darran	0:55a05330f8cc	579	LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
darran	0:55a05330f8cc	580	prev_seg->next = seg;
darran	0:55a05330f8cc	581	}
darran	0:55a05330f8cc	582	/* remember last segment of to-be-queued data for next iteration */
darran	0:55a05330f8cc	583	prev_seg = seg;
darran	0:55a05330f8cc	584
darran	0:55a05330f8cc	585	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
darran	0:55a05330f8cc	586	ntohl(seg->tcphdr->seqno),
darran	0:55a05330f8cc	587	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
darran	0:55a05330f8cc	588
darran	0:55a05330f8cc	589	pos += seglen;
darran	0:55a05330f8cc	590	}
darran	0:55a05330f8cc	591
darran	0:55a05330f8cc	592	/*
darran	0:55a05330f8cc	593	* All three segmentation phases were successful. We can commit the
darran	0:55a05330f8cc	594	* transaction.
darran	0:55a05330f8cc	595	*/
darran	0:55a05330f8cc	596
darran	0:55a05330f8cc	597	/*
darran	0:55a05330f8cc	598	* Phase 1: If data has been added to the preallocated tail of
darran	0:55a05330f8cc	599	* last_unsent, we update the length fields of the pbuf chain.
darran	0:55a05330f8cc	600	*/
darran	0:55a05330f8cc	601	#if TCP_OVERSIZE
darran	0:55a05330f8cc	602	if (oversize_used > 0) {
darran	0:55a05330f8cc	603	struct pbuf *p;
darran	0:55a05330f8cc	604	/* Bump tot_len of whole chain, len of tail */
darran	0:55a05330f8cc	605	for (p = last_unsent->p; p; p = p->next) {
darran	0:55a05330f8cc	606	p->tot_len += oversize_used;
darran	0:55a05330f8cc	607	if (p->next == NULL) {
darran	0:55a05330f8cc	608	TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
darran	0:55a05330f8cc	609	p->len += oversize_used;
darran	0:55a05330f8cc	610	}
darran	0:55a05330f8cc	611	}
darran	0:55a05330f8cc	612	last_unsent->len += oversize_used;
darran	0:55a05330f8cc	613	#if TCP_OVERSIZE_DBGCHECK
darran	0:55a05330f8cc	614	last_unsent->oversize_left -= oversize_used;
darran	0:55a05330f8cc	615	#endif /* TCP_OVERSIZE_DBGCHECK */
darran	0:55a05330f8cc	616	}
darran	0:55a05330f8cc	617	pcb->unsent_oversize = oversize;
darran	0:55a05330f8cc	618	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	619
darran	0:55a05330f8cc	620	/*
darran	0:55a05330f8cc	621	* Phase 2: concat_p can be concatenated onto last_unsent->p
darran	0:55a05330f8cc	622	*/
darran	0:55a05330f8cc	623	if (concat_p != NULL) {
darran	0:55a05330f8cc	624	LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
darran	0:55a05330f8cc	625	(last_unsent != NULL));
darran	0:55a05330f8cc	626	pbuf_cat(last_unsent->p, concat_p);
darran	0:55a05330f8cc	627	last_unsent->len += concat_p->tot_len;
darran	0:55a05330f8cc	628	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	629	if (concat_chksummed) {
darran	0:55a05330f8cc	630	tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
darran	0:55a05330f8cc	631	&last_unsent->chksum_swapped);
darran	0:55a05330f8cc	632	last_unsent->flags \|= TF_SEG_DATA_CHECKSUMMED;
darran	0:55a05330f8cc	633	}
darran	0:55a05330f8cc	634	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	635	}
darran	0:55a05330f8cc	636
darran	0:55a05330f8cc	637	/*
darran	0:55a05330f8cc	638	* Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
darran	0:55a05330f8cc	639	* is harmless
darran	0:55a05330f8cc	640	*/
darran	0:55a05330f8cc	641	if (last_unsent == NULL) {
darran	0:55a05330f8cc	642	pcb->unsent = queue;
darran	0:55a05330f8cc	643	} else {
darran	0:55a05330f8cc	644	last_unsent->next = queue;
darran	0:55a05330f8cc	645	}
darran	0:55a05330f8cc	646
darran	0:55a05330f8cc	647	/*
darran	0:55a05330f8cc	648	* Finally update the pcb state.
darran	0:55a05330f8cc	649	*/
darran	0:55a05330f8cc	650	pcb->snd_lbb += len;
darran	0:55a05330f8cc	651	pcb->snd_buf -= len;
darran	0:55a05330f8cc	652	pcb->snd_queuelen = queuelen;
darran	0:55a05330f8cc	653
darran	0:55a05330f8cc	654	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
darran	0:55a05330f8cc	655	pcb->snd_queuelen));
darran	0:55a05330f8cc	656	if (pcb->snd_queuelen != 0) {
darran	0:55a05330f8cc	657	LWIP_ASSERT("tcp_write: valid queue length",
darran	0:55a05330f8cc	658	pcb->unacked != NULL \|\| pcb->unsent != NULL);
darran	0:55a05330f8cc	659	}
darran	0:55a05330f8cc	660
darran	0:55a05330f8cc	661	/* Set the PSH flag in the last segment that we enqueued. */
darran	0:55a05330f8cc	662	if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
darran	0:55a05330f8cc	663	TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
darran	0:55a05330f8cc	664	}
darran	0:55a05330f8cc	665
darran	0:55a05330f8cc	666	return ERR_OK;
darran	0:55a05330f8cc	667	memerr:
darran	0:55a05330f8cc	668	pcb->flags \|= TF_NAGLEMEMERR;
darran	0:55a05330f8cc	669	TCP_STATS_INC(tcp.memerr);
darran	0:55a05330f8cc	670
darran	0:55a05330f8cc	671	if (concat_p != NULL) {
darran	0:55a05330f8cc	672	pbuf_free(concat_p);
darran	0:55a05330f8cc	673	}
darran	0:55a05330f8cc	674	if (queue != NULL) {
darran	0:55a05330f8cc	675	tcp_segs_free(queue);
darran	0:55a05330f8cc	676	}
darran	0:55a05330f8cc	677	if (pcb->snd_queuelen != 0) {
darran	0:55a05330f8cc	678	LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL \|\|
darran	0:55a05330f8cc	679	pcb->unsent != NULL);
darran	0:55a05330f8cc	680	}
darran	0:55a05330f8cc	681	LWIP_DEBUGF(TCP_QLEN_DEBUG \| LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
darran	0:55a05330f8cc	682	return ERR_MEM;
darran	0:55a05330f8cc	683	}
darran	0:55a05330f8cc	684
darran	0:55a05330f8cc	685	/**
darran	0:55a05330f8cc	686	* Enqueue TCP options for transmission.
darran	0:55a05330f8cc	687	*
darran	0:55a05330f8cc	688	* Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
darran	0:55a05330f8cc	689	*
darran	0:55a05330f8cc	690	* @param pcb Protocol control block for the TCP connection.
darran	0:55a05330f8cc	691	* @param flags TCP header flags to set in the outgoing segment.
darran	0:55a05330f8cc	692	* @param optdata pointer to TCP options, or NULL.
darran	0:55a05330f8cc	693	* @param optlen length of TCP options in bytes.
darran	0:55a05330f8cc	694	*/
darran	0:55a05330f8cc	695	err_t
darran	0:55a05330f8cc	696	tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
darran	0:55a05330f8cc	697	{
darran	0:55a05330f8cc	698	struct pbuf *p;
darran	0:55a05330f8cc	699	struct tcp_seg *seg;
darran	0:55a05330f8cc	700	u8_t optflags = 0;
darran	0:55a05330f8cc	701	u8_t optlen = 0;
darran	0:55a05330f8cc	702
darran	0:55a05330f8cc	703	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
darran	0:55a05330f8cc	704
darran	0:55a05330f8cc	705	LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
darran	0:55a05330f8cc	706	(flags & (TCP_SYN \| TCP_FIN)) != 0);
darran	0:55a05330f8cc	707
darran	0:55a05330f8cc	708	/* check for configured max queuelen and possible overflow */
darran	0:55a05330f8cc	709	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
darran	0:55a05330f8cc	710	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
darran	0:55a05330f8cc	711	pcb->snd_queuelen, TCP_SND_QUEUELEN));
darran	0:55a05330f8cc	712	TCP_STATS_INC(tcp.memerr);
darran	0:55a05330f8cc	713	pcb->flags \|= TF_NAGLEMEMERR;
darran	0:55a05330f8cc	714	return ERR_MEM;
darran	0:55a05330f8cc	715	}
darran	0:55a05330f8cc	716
darran	0:55a05330f8cc	717	if (flags & TCP_SYN) {
darran	0:55a05330f8cc	718	optflags = TF_SEG_OPTS_MSS;
darran	0:55a05330f8cc	719	}
darran	0:55a05330f8cc	720	#if LWIP_TCP_TIMESTAMPS
darran	0:55a05330f8cc	721	if ((pcb->flags & TF_TIMESTAMP)) {
darran	0:55a05330f8cc	722	optflags \|= TF_SEG_OPTS_TS;
darran	0:55a05330f8cc	723	}
darran	0:55a05330f8cc	724	#endif /* LWIP_TCP_TIMESTAMPS */
darran	0:55a05330f8cc	725	optlen = LWIP_TCP_OPT_LENGTH(optflags);
darran	0:55a05330f8cc	726
darran	0:55a05330f8cc	727	/* tcp_enqueue_flags is always called with either SYN or FIN in flags.
darran	0:55a05330f8cc	728	* We need one available snd_buf byte to do that.
darran	0:55a05330f8cc	729	* This means we can't send FIN while snd_buf==0. A better fix would be to
darran	0:55a05330f8cc	730	* not include SYN and FIN sequence numbers in the snd_buf count. */
darran	0:55a05330f8cc	731	if (pcb->snd_buf == 0) {
darran	0:55a05330f8cc	732	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: no send buffer available\n"));
darran	0:55a05330f8cc	733	TCP_STATS_INC(tcp.memerr);
darran	0:55a05330f8cc	734	return ERR_MEM;
darran	0:55a05330f8cc	735	}
darran	0:55a05330f8cc	736
darran	0:55a05330f8cc	737	/* Allocate pbuf with room for TCP header + options */
darran	0:55a05330f8cc	738	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
darran	0:55a05330f8cc	739	pcb->flags \|= TF_NAGLEMEMERR;
darran	0:55a05330f8cc	740	TCP_STATS_INC(tcp.memerr);
darran	0:55a05330f8cc	741	return ERR_MEM;
darran	0:55a05330f8cc	742	}
darran	0:55a05330f8cc	743	LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
darran	0:55a05330f8cc	744	(p->len >= optlen));
darran	0:55a05330f8cc	745
darran	0:55a05330f8cc	746	/* Allocate memory for tcp_seg, and fill in fields. */
darran	0:55a05330f8cc	747	if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
darran	0:55a05330f8cc	748	pcb->flags \|= TF_NAGLEMEMERR;
darran	0:55a05330f8cc	749	TCP_STATS_INC(tcp.memerr);
darran	0:55a05330f8cc	750	return ERR_MEM;
darran	0:55a05330f8cc	751	}
darran	0:55a05330f8cc	752	LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
darran	0:55a05330f8cc	753
darran	0:55a05330f8cc	754	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE,
darran	0:55a05330f8cc	755	("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
darran	0:55a05330f8cc	756	ntohl(seg->tcphdr->seqno),
darran	0:55a05330f8cc	757	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
darran	0:55a05330f8cc	758	(u16_t)flags));
darran	0:55a05330f8cc	759
darran	0:55a05330f8cc	760	/* Now append seg to pcb->unsent queue */
darran	0:55a05330f8cc	761	if (pcb->unsent == NULL) {
darran	0:55a05330f8cc	762	pcb->unsent = seg;
darran	0:55a05330f8cc	763	} else {
darran	0:55a05330f8cc	764	struct tcp_seg *useg;
darran	0:55a05330f8cc	765	for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
darran	0:55a05330f8cc	766	useg->next = seg;
darran	0:55a05330f8cc	767	}
darran	0:55a05330f8cc	768	#if TCP_OVERSIZE
darran	0:55a05330f8cc	769	/* The new unsent tail has no space */
darran	0:55a05330f8cc	770	pcb->unsent_oversize = 0;
darran	0:55a05330f8cc	771	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	772
darran	0:55a05330f8cc	773	/* SYN and FIN bump the sequence number */
darran	0:55a05330f8cc	774	if ((flags & TCP_SYN) \|\| (flags & TCP_FIN)) {
darran	0:55a05330f8cc	775	pcb->snd_lbb++;
darran	0:55a05330f8cc	776	/* optlen does not influence snd_buf */
darran	0:55a05330f8cc	777	pcb->snd_buf--;
darran	0:55a05330f8cc	778	}
darran	0:55a05330f8cc	779	if (flags & TCP_FIN) {
darran	0:55a05330f8cc	780	pcb->flags \|= TF_FIN;
darran	0:55a05330f8cc	781	}
darran	0:55a05330f8cc	782
darran	0:55a05330f8cc	783	/* update number of segments on the queues */
darran	0:55a05330f8cc	784	pcb->snd_queuelen += pbuf_clen(seg->p);
darran	0:55a05330f8cc	785	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
darran	0:55a05330f8cc	786	if (pcb->snd_queuelen != 0) {
darran	0:55a05330f8cc	787	LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
darran	0:55a05330f8cc	788	pcb->unacked != NULL \|\| pcb->unsent != NULL);
darran	0:55a05330f8cc	789	}
darran	0:55a05330f8cc	790
darran	0:55a05330f8cc	791	return ERR_OK;
darran	0:55a05330f8cc	792	}
darran	0:55a05330f8cc	793
darran	0:55a05330f8cc	794
darran	0:55a05330f8cc	795	#if LWIP_TCP_TIMESTAMPS
darran	0:55a05330f8cc	796	/* Build a timestamp option (12 bytes long) at the specified options pointer)
darran	0:55a05330f8cc	797	*
darran	0:55a05330f8cc	798	* @param pcb tcp_pcb
darran	0:55a05330f8cc	799	* @param opts option pointer where to store the timestamp option
darran	0:55a05330f8cc	800	*/
darran	0:55a05330f8cc	801	static void
darran	0:55a05330f8cc	802	tcp_build_timestamp_option(struct tcp_pcb pcb, u32_t opts)
darran	0:55a05330f8cc	803	{
darran	0:55a05330f8cc	804	/* Pad with two NOP options to make everything nicely aligned */
darran	0:55a05330f8cc	805	opts[0] = htonl(0x0101080A);
darran	0:55a05330f8cc	806	opts[1] = htonl(sys_now());
darran	0:55a05330f8cc	807	opts[2] = htonl(pcb->ts_recent);
darran	0:55a05330f8cc	808	}
darran	0:55a05330f8cc	809	#endif
darran	0:55a05330f8cc	810
darran	0:55a05330f8cc	811	/** Send an ACK without data.
darran	0:55a05330f8cc	812	*
darran	0:55a05330f8cc	813	* @param pcb Protocol control block for the TCP connection to send the ACK
darran	0:55a05330f8cc	814	*/
darran	0:55a05330f8cc	815	err_t
darran	0:55a05330f8cc	816	tcp_send_empty_ack(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	817	{
darran	0:55a05330f8cc	818	struct pbuf *p;
darran	0:55a05330f8cc	819	struct tcp_hdr *tcphdr;
darran	0:55a05330f8cc	820	u8_t optlen = 0;
darran	0:55a05330f8cc	821
darran	0:55a05330f8cc	822	#if LWIP_TCP_TIMESTAMPS
darran	0:55a05330f8cc	823	if (pcb->flags & TF_TIMESTAMP) {
darran	0:55a05330f8cc	824	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
darran	0:55a05330f8cc	825	}
darran	0:55a05330f8cc	826	#endif
darran	0:55a05330f8cc	827
darran	0:55a05330f8cc	828	p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
darran	0:55a05330f8cc	829	if (p == NULL) {
darran	0:55a05330f8cc	830	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
darran	0:55a05330f8cc	831	return ERR_BUF;
darran	0:55a05330f8cc	832	}
darran	0:55a05330f8cc	833	tcphdr = (struct tcp_hdr *)p->payload;
darran	0:55a05330f8cc	834	LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
darran	0:55a05330f8cc	835	("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
darran	0:55a05330f8cc	836	/* remove ACK flags from the PCB, as we send an empty ACK now */
darran	0:55a05330f8cc	837	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
darran	0:55a05330f8cc	838
darran	0:55a05330f8cc	839	/* NB. MSS option is only sent on SYNs, so ignore it here */
darran	0:55a05330f8cc	840	#if LWIP_TCP_TIMESTAMPS
darran	0:55a05330f8cc	841	pcb->ts_lastacksent = pcb->rcv_nxt;
darran	0:55a05330f8cc	842
darran	0:55a05330f8cc	843	if (pcb->flags & TF_TIMESTAMP) {
darran	0:55a05330f8cc	844	tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
darran	0:55a05330f8cc	845	}
darran	0:55a05330f8cc	846	#endif
darran	0:55a05330f8cc	847
darran	0:55a05330f8cc	848	#if CHECKSUM_GEN_TCP
darran	0:55a05330f8cc	849	tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
darran	0:55a05330f8cc	850	IP_PROTO_TCP, p->tot_len);
darran	0:55a05330f8cc	851	#endif
darran	0:55a05330f8cc	852	#if LWIP_NETIF_HWADDRHINT
darran	0:55a05330f8cc	853	ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
darran	0:55a05330f8cc	854	IP_PROTO_TCP, &(pcb->addr_hint));
darran	0:55a05330f8cc	855	#else /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	856	ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
darran	0:55a05330f8cc	857	IP_PROTO_TCP);
darran	0:55a05330f8cc	858	#endif /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	859	pbuf_free(p);
darran	0:55a05330f8cc	860
darran	0:55a05330f8cc	861	return ERR_OK;
darran	0:55a05330f8cc	862	}
darran	0:55a05330f8cc	863
darran	0:55a05330f8cc	864	/**
darran	0:55a05330f8cc	865	* Find out what we can send and send it
darran	0:55a05330f8cc	866	*
darran	0:55a05330f8cc	867	* @param pcb Protocol control block for the TCP connection to send data
darran	0:55a05330f8cc	868	* @return ERR_OK if data has been sent or nothing to send
darran	0:55a05330f8cc	869	* another err_t on error
darran	0:55a05330f8cc	870	*/
darran	0:55a05330f8cc	871	err_t
darran	0:55a05330f8cc	872	tcp_output(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	873	{
darran	0:55a05330f8cc	874	struct tcp_seg seg, useg;
darran	0:55a05330f8cc	875	u32_t wnd, snd_nxt;
darran	0:55a05330f8cc	876	#if TCP_CWND_DEBUG
darran	0:55a05330f8cc	877	s16_t i = 0;
darran	0:55a05330f8cc	878	#endif /* TCP_CWND_DEBUG */
darran	0:55a05330f8cc	879
darran	0:55a05330f8cc	880	/* First, check if we are invoked by the TCP input processing
darran	0:55a05330f8cc	881	code. If so, we do not output anything. Instead, we rely on the
darran	0:55a05330f8cc	882	input processing code to call us when input processing is done
darran	0:55a05330f8cc	883	with. */
darran	0:55a05330f8cc	884	if (tcp_input_pcb == pcb) {
darran	0:55a05330f8cc	885	return ERR_OK;
darran	0:55a05330f8cc	886	}
darran	0:55a05330f8cc	887
darran	0:55a05330f8cc	888	wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
darran	0:55a05330f8cc	889
darran	0:55a05330f8cc	890	seg = pcb->unsent;
darran	0:55a05330f8cc	891
darran	0:55a05330f8cc	892	/* If the TF_ACK_NOW flag is set and no data will be sent (either
darran	0:55a05330f8cc	893	* because the ->unsent queue is empty or because the window does
darran	0:55a05330f8cc	894	* not allow it), construct an empty ACK segment and send it.
darran	0:55a05330f8cc	895	*
darran	0:55a05330f8cc	896	* If data is to be sent, we will just piggyback the ACK (see below).
darran	0:55a05330f8cc	897	*/
darran	0:55a05330f8cc	898	if (pcb->flags & TF_ACK_NOW &&
darran	0:55a05330f8cc	899	(seg == NULL \|\|
darran	0:55a05330f8cc	900	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
darran	0:55a05330f8cc	901	return tcp_send_empty_ack(pcb);
darran	0:55a05330f8cc	902	}
darran	0:55a05330f8cc	903
darran	0:55a05330f8cc	904	/* useg should point to last segment on unacked queue */
darran	0:55a05330f8cc	905	useg = pcb->unacked;
darran	0:55a05330f8cc	906	if (useg != NULL) {
darran	0:55a05330f8cc	907	for (; useg->next != NULL; useg = useg->next);
darran	0:55a05330f8cc	908	}
darran	0:55a05330f8cc	909
darran	0:55a05330f8cc	910	#if TCP_OUTPUT_DEBUG
darran	0:55a05330f8cc	911	if (seg == NULL) {
darran	0:55a05330f8cc	912	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
darran	0:55a05330f8cc	913	(void*)pcb->unsent));
darran	0:55a05330f8cc	914	}
darran	0:55a05330f8cc	915	#endif /* TCP_OUTPUT_DEBUG */
darran	0:55a05330f8cc	916	#if TCP_CWND_DEBUG
darran	0:55a05330f8cc	917	if (seg == NULL) {
darran	0:55a05330f8cc	918	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
darran	0:55a05330f8cc	919	", cwnd %"U16_F", wnd %"U32_F
darran	0:55a05330f8cc	920	", seg == NULL, ack %"U32_F"\n",
darran	0:55a05330f8cc	921	pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
darran	0:55a05330f8cc	922	} else {
darran	0:55a05330f8cc	923	LWIP_DEBUGF(TCP_CWND_DEBUG,
darran	0:55a05330f8cc	924	("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
darran	0:55a05330f8cc	925	", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
darran	0:55a05330f8cc	926	pcb->snd_wnd, pcb->cwnd, wnd,
darran	0:55a05330f8cc	927	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
darran	0:55a05330f8cc	928	ntohl(seg->tcphdr->seqno), pcb->lastack));
darran	0:55a05330f8cc	929	}
darran	0:55a05330f8cc	930	#endif /* TCP_CWND_DEBUG */
darran	0:55a05330f8cc	931	/* data available and window allows it to be sent? */
darran	0:55a05330f8cc	932	while (seg != NULL &&
darran	0:55a05330f8cc	933	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
darran	0:55a05330f8cc	934	LWIP_ASSERT("RST not expected here!",
darran	0:55a05330f8cc	935	(TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
darran	0:55a05330f8cc	936	/* Stop sending if the nagle algorithm would prevent it
darran	0:55a05330f8cc	937	* Don't stop:
darran	0:55a05330f8cc	938	* - if tcp_write had a memory error before (prevent delayed ACK timeout) or
darran	0:55a05330f8cc	939	* - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
darran	0:55a05330f8cc	940	* either seg->next != NULL or pcb->unacked == NULL;
darran	0:55a05330f8cc	941	* RST is no sent using tcp_write/tcp_output.
darran	0:55a05330f8cc	942	*/
darran	0:55a05330f8cc	943	if((tcp_do_output_nagle(pcb) == 0) &&
darran	0:55a05330f8cc	944	((pcb->flags & (TF_NAGLEMEMERR \| TF_FIN)) == 0)){
darran	0:55a05330f8cc	945	break;
darran	0:55a05330f8cc	946	}
darran	0:55a05330f8cc	947	#if TCP_CWND_DEBUG
darran	0:55a05330f8cc	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",
darran	0:55a05330f8cc	949	pcb->snd_wnd, pcb->cwnd, wnd,
darran	0:55a05330f8cc	950	ntohl(seg->tcphdr->seqno) + seg->len -
darran	0:55a05330f8cc	951	pcb->lastack,
darran	0:55a05330f8cc	952	ntohl(seg->tcphdr->seqno), pcb->lastack, i));
darran	0:55a05330f8cc	953	++i;
darran	0:55a05330f8cc	954	#endif /* TCP_CWND_DEBUG */
darran	0:55a05330f8cc	955
darran	0:55a05330f8cc	956	pcb->unsent = seg->next;
darran	0:55a05330f8cc	957
darran	0:55a05330f8cc	958	if (pcb->state != SYN_SENT) {
darran	0:55a05330f8cc	959	TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
darran	0:55a05330f8cc	960	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
darran	0:55a05330f8cc	961	}
darran	0:55a05330f8cc	962
darran	0:55a05330f8cc	963	tcp_output_segment(seg, pcb);
darran	0:55a05330f8cc	964	snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
darran	0:55a05330f8cc	965	if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
darran	0:55a05330f8cc	966	pcb->snd_nxt = snd_nxt;
darran	0:55a05330f8cc	967	}
darran	0:55a05330f8cc	968	/* put segment on unacknowledged list if length > 0 */
darran	0:55a05330f8cc	969	if (TCP_TCPLEN(seg) > 0) {
darran	0:55a05330f8cc	970	seg->next = NULL;
darran	0:55a05330f8cc	971	/* unacked list is empty? */
darran	0:55a05330f8cc	972	if (pcb->unacked == NULL) {
darran	0:55a05330f8cc	973	pcb->unacked = seg;
darran	0:55a05330f8cc	974	useg = seg;
darran	0:55a05330f8cc	975	/* unacked list is not empty? */
darran	0:55a05330f8cc	976	} else {
darran	0:55a05330f8cc	977	/* In the case of fast retransmit, the packet should not go to the tail
darran	0:55a05330f8cc	978	* of the unacked queue, but rather somewhere before it. We need to check for
darran	0:55a05330f8cc	979	* this case. -STJ Jul 27, 2004 */
darran	0:55a05330f8cc	980	if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
darran	0:55a05330f8cc	981	/* add segment to before tail of unacked list, keeping the list sorted */
darran	0:55a05330f8cc	982	struct tcp_seg **cur_seg = &(pcb->unacked);
darran	0:55a05330f8cc	983	while (*cur_seg &&
darran	0:55a05330f8cc	984	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
darran	0:55a05330f8cc	985	cur_seg = &((*cur_seg)->next );
darran	0:55a05330f8cc	986	}
darran	0:55a05330f8cc	987	seg->next = (*cur_seg);
darran	0:55a05330f8cc	988	(*cur_seg) = seg;
darran	0:55a05330f8cc	989	} else {
darran	0:55a05330f8cc	990	/* add segment to tail of unacked list */
darran	0:55a05330f8cc	991	useg->next = seg;
darran	0:55a05330f8cc	992	useg = useg->next;
darran	0:55a05330f8cc	993	}
darran	0:55a05330f8cc	994	}
darran	0:55a05330f8cc	995	/* do not queue empty segments on the unacked list */
darran	0:55a05330f8cc	996	} else {
darran	0:55a05330f8cc	997	tcp_seg_free(seg);
darran	0:55a05330f8cc	998	}
darran	0:55a05330f8cc	999	seg = pcb->unsent;
darran	0:55a05330f8cc	1000	}
darran	0:55a05330f8cc	1001	#if TCP_OVERSIZE
darran	0:55a05330f8cc	1002	if (pcb->unsent == NULL) {
darran	0:55a05330f8cc	1003	/* last unsent has been removed, reset unsent_oversize */
darran	0:55a05330f8cc	1004	pcb->unsent_oversize = 0;
darran	0:55a05330f8cc	1005	}
darran	0:55a05330f8cc	1006	#endif /* TCP_OVERSIZE */
darran	0:55a05330f8cc	1007
darran	0:55a05330f8cc	1008	if (seg != NULL && pcb->persist_backoff == 0 &&
darran	0:55a05330f8cc	1009	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) {
darran	0:55a05330f8cc	1010	/* prepare for persist timer */
darran	0:55a05330f8cc	1011	pcb->persist_cnt = 0;
darran	0:55a05330f8cc	1012	pcb->persist_backoff = 1;
darran	0:55a05330f8cc	1013	}
darran	0:55a05330f8cc	1014
darran	0:55a05330f8cc	1015	pcb->flags &= ~TF_NAGLEMEMERR;
darran	0:55a05330f8cc	1016	return ERR_OK;
darran	0:55a05330f8cc	1017	}
darran	0:55a05330f8cc	1018
darran	0:55a05330f8cc	1019	/**
darran	0:55a05330f8cc	1020	* Called by tcp_output() to actually send a TCP segment over IP.
darran	0:55a05330f8cc	1021	*
darran	0:55a05330f8cc	1022	* @param seg the tcp_seg to send
darran	0:55a05330f8cc	1023	* @param pcb the tcp_pcb for the TCP connection used to send the segment
darran	0:55a05330f8cc	1024	*/
darran	0:55a05330f8cc	1025	static void
darran	0:55a05330f8cc	1026	tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb)
darran	0:55a05330f8cc	1027	{
darran	0:55a05330f8cc	1028	u16_t len;
darran	0:55a05330f8cc	1029	struct netif *netif;
darran	0:55a05330f8cc	1030	u32_t *opts;
darran	0:55a05330f8cc	1031
darran	0:55a05330f8cc	1032	/** @bug Exclude retransmitted segments from this count. */
darran	0:55a05330f8cc	1033	snmp_inc_tcpoutsegs();
darran	0:55a05330f8cc	1034
darran	0:55a05330f8cc	1035	/* The TCP header has already been constructed, but the ackno and
darran	0:55a05330f8cc	1036	wnd fields remain. */
darran	0:55a05330f8cc	1037	seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
darran	0:55a05330f8cc	1038
darran	0:55a05330f8cc	1039	/* advertise our receive window size in this TCP segment */
darran	0:55a05330f8cc	1040	seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
darran	0:55a05330f8cc	1041
darran	0:55a05330f8cc	1042	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
darran	0:55a05330f8cc	1043
darran	0:55a05330f8cc	1044	/* Add any requested options. NB MSS option is only set on SYN
darran	0:55a05330f8cc	1045	packets, so ignore it here */
darran	0:55a05330f8cc	1046	LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
darran	0:55a05330f8cc	1047	opts = (u32_t )(void )(seg->tcphdr + 1);
darran	0:55a05330f8cc	1048	if (seg->flags & TF_SEG_OPTS_MSS) {
darran	0:55a05330f8cc	1049	TCP_BUILD_MSS_OPTION(*opts);
darran	0:55a05330f8cc	1050	opts += 1;
darran	0:55a05330f8cc	1051	}
darran	0:55a05330f8cc	1052	#if LWIP_TCP_TIMESTAMPS
darran	0:55a05330f8cc	1053	pcb->ts_lastacksent = pcb->rcv_nxt;
darran	0:55a05330f8cc	1054
darran	0:55a05330f8cc	1055	if (seg->flags & TF_SEG_OPTS_TS) {
darran	0:55a05330f8cc	1056	tcp_build_timestamp_option(pcb, opts);
darran	0:55a05330f8cc	1057	opts += 3;
darran	0:55a05330f8cc	1058	}
darran	0:55a05330f8cc	1059	#endif
darran	0:55a05330f8cc	1060
darran	0:55a05330f8cc	1061	/* If we don't have a local IP address, we get one by
darran	0:55a05330f8cc	1062	calling ip_route(). */
darran	0:55a05330f8cc	1063	if (ip_addr_isany(&(pcb->local_ip))) {
darran	0:55a05330f8cc	1064	netif = ip_route(&(pcb->remote_ip));
darran	0:55a05330f8cc	1065	if (netif == NULL) {
darran	0:55a05330f8cc	1066	return;
darran	0:55a05330f8cc	1067	}
darran	0:55a05330f8cc	1068	ip_addr_copy(pcb->local_ip, netif->ip_addr);
darran	0:55a05330f8cc	1069	}
darran	0:55a05330f8cc	1070
darran	0:55a05330f8cc	1071	/* Set retransmission timer running if it is not currently enabled */
darran	0:55a05330f8cc	1072	if(pcb->rtime == -1) {
darran	0:55a05330f8cc	1073	pcb->rtime = 0;
darran	0:55a05330f8cc	1074	}
darran	0:55a05330f8cc	1075
darran	0:55a05330f8cc	1076	if (pcb->rttest == 0) {
darran	0:55a05330f8cc	1077	pcb->rttest = tcp_ticks;
darran	0:55a05330f8cc	1078	pcb->rtseq = ntohl(seg->tcphdr->seqno);
darran	0:55a05330f8cc	1079
darran	0:55a05330f8cc	1080	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
darran	0:55a05330f8cc	1081	}
darran	0:55a05330f8cc	1082	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
darran	0:55a05330f8cc	1083	htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
darran	0:55a05330f8cc	1084	seg->len));
darran	0:55a05330f8cc	1085
darran	0:55a05330f8cc	1086	len = (u16_t)((u8_t )seg->tcphdr - (u8_t )seg->p->payload);
darran	0:55a05330f8cc	1087
darran	0:55a05330f8cc	1088	seg->p->len -= len;
darran	0:55a05330f8cc	1089	seg->p->tot_len -= len;
darran	0:55a05330f8cc	1090
darran	0:55a05330f8cc	1091	seg->p->payload = seg->tcphdr;
darran	0:55a05330f8cc	1092
darran	0:55a05330f8cc	1093	seg->tcphdr->chksum = 0;
darran	0:55a05330f8cc	1094	#if CHECKSUM_GEN_TCP
darran	0:55a05330f8cc	1095	#if TCP_CHECKSUM_ON_COPY
darran	0:55a05330f8cc	1096	{
darran	0:55a05330f8cc	1097	u32_t acc;
darran	0:55a05330f8cc	1098	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
darran	0:55a05330f8cc	1099	u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
darran	0:55a05330f8cc	1100	&(pcb->remote_ip),
darran	0:55a05330f8cc	1101	IP_PROTO_TCP, seg->p->tot_len);
darran	0:55a05330f8cc	1102	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
darran	0:55a05330f8cc	1103	if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
darran	0:55a05330f8cc	1104	LWIP_ASSERT("data included but not checksummed",
darran	0:55a05330f8cc	1105	seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
darran	0:55a05330f8cc	1106	}
darran	0:55a05330f8cc	1107
darran	0:55a05330f8cc	1108	/* rebuild TCP header checksum (TCP header changes for retransmissions!) */
darran	0:55a05330f8cc	1109	acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
darran	0:55a05330f8cc	1110	&(pcb->remote_ip),
darran	0:55a05330f8cc	1111	IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
darran	0:55a05330f8cc	1112	/* add payload checksum */
darran	0:55a05330f8cc	1113	if (seg->chksum_swapped) {
darran	0:55a05330f8cc	1114	seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
darran	0:55a05330f8cc	1115	seg->chksum_swapped = 0;
darran	0:55a05330f8cc	1116	}
darran	0:55a05330f8cc	1117	acc += (u16_t)~(seg->chksum);
darran	0:55a05330f8cc	1118	seg->tcphdr->chksum = FOLD_U32T(acc);
darran	0:55a05330f8cc	1119	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
darran	0:55a05330f8cc	1120	if (chksum_slow != seg->tcphdr->chksum) {
darran	0:55a05330f8cc	1121	LWIP_DEBUGF(TCP_DEBUG \| LWIP_DBG_LEVEL_WARNING,
darran	0:55a05330f8cc	1122	("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
darran	0:55a05330f8cc	1123	seg->tcphdr->chksum, chksum_slow));
darran	0:55a05330f8cc	1124	seg->tcphdr->chksum = chksum_slow;
darran	0:55a05330f8cc	1125	}
darran	0:55a05330f8cc	1126	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
darran	0:55a05330f8cc	1127	}
darran	0:55a05330f8cc	1128	#else /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	1129	seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
darran	0:55a05330f8cc	1130	&(pcb->remote_ip),
darran	0:55a05330f8cc	1131	IP_PROTO_TCP, seg->p->tot_len);
darran	0:55a05330f8cc	1132	#endif /* TCP_CHECKSUM_ON_COPY */
darran	0:55a05330f8cc	1133	#endif /* CHECKSUM_GEN_TCP */
darran	0:55a05330f8cc	1134	TCP_STATS_INC(tcp.xmit);
darran	0:55a05330f8cc	1135
darran	0:55a05330f8cc	1136	#if LWIP_NETIF_HWADDRHINT
darran	0:55a05330f8cc	1137	ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
darran	0:55a05330f8cc	1138	IP_PROTO_TCP, &(pcb->addr_hint));
darran	0:55a05330f8cc	1139	#else /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	1140	ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
darran	0:55a05330f8cc	1141	IP_PROTO_TCP);
darran	0:55a05330f8cc	1142	#endif /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	1143	}
darran	0:55a05330f8cc	1144
darran	0:55a05330f8cc	1145	/**
darran	0:55a05330f8cc	1146	* Send a TCP RESET packet (empty segment with RST flag set) either to
darran	0:55a05330f8cc	1147	* abort a connection or to show that there is no matching local connection
darran	0:55a05330f8cc	1148	* for a received segment.
darran	0:55a05330f8cc	1149	*
darran	0:55a05330f8cc	1150	* Called by tcp_abort() (to abort a local connection), tcp_input() (if no
darran	0:55a05330f8cc	1151	* matching local pcb was found), tcp_listen_input() (if incoming segment
darran	0:55a05330f8cc	1152	* has ACK flag set) and tcp_process() (received segment in the wrong state)
darran	0:55a05330f8cc	1153	*
darran	0:55a05330f8cc	1154	* Since a RST segment is in most cases not sent for an active connection,
darran	0:55a05330f8cc	1155	* tcp_rst() has a number of arguments that are taken from a tcp_pcb for
darran	0:55a05330f8cc	1156	* most other segment output functions.
darran	0:55a05330f8cc	1157	*
darran	0:55a05330f8cc	1158	* @param seqno the sequence number to use for the outgoing segment
darran	0:55a05330f8cc	1159	* @param ackno the acknowledge number to use for the outgoing segment
darran	0:55a05330f8cc	1160	* @param local_ip the local IP address to send the segment from
darran	0:55a05330f8cc	1161	* @param remote_ip the remote IP address to send the segment to
darran	0:55a05330f8cc	1162	* @param local_port the local TCP port to send the segment from
darran	0:55a05330f8cc	1163	* @param remote_port the remote TCP port to send the segment to
darran	0:55a05330f8cc	1164	*/
darran	0:55a05330f8cc	1165	void
darran	0:55a05330f8cc	1166	tcp_rst(u32_t seqno, u32_t ackno,
darran	0:55a05330f8cc	1167	ip_addr_t local_ip, ip_addr_t remote_ip,
darran	0:55a05330f8cc	1168	u16_t local_port, u16_t remote_port)
darran	0:55a05330f8cc	1169	{
darran	0:55a05330f8cc	1170	struct pbuf *p;
darran	0:55a05330f8cc	1171	struct tcp_hdr *tcphdr;
darran	0:55a05330f8cc	1172	p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
darran	0:55a05330f8cc	1173	if (p == NULL) {
darran	0:55a05330f8cc	1174	LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
darran	0:55a05330f8cc	1175	return;
darran	0:55a05330f8cc	1176	}
darran	0:55a05330f8cc	1177	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
darran	0:55a05330f8cc	1178	(p->len >= sizeof(struct tcp_hdr)));
darran	0:55a05330f8cc	1179
darran	0:55a05330f8cc	1180	tcphdr = (struct tcp_hdr *)p->payload;
darran	0:55a05330f8cc	1181	tcphdr->src = htons(local_port);
darran	0:55a05330f8cc	1182	tcphdr->dest = htons(remote_port);
darran	0:55a05330f8cc	1183	tcphdr->seqno = htonl(seqno);
darran	0:55a05330f8cc	1184	tcphdr->ackno = htonl(ackno);
darran	0:55a05330f8cc	1185	TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST \| TCP_ACK);
darran	0:55a05330f8cc	1186	tcphdr->wnd = htons(TCP_WND);
darran	0:55a05330f8cc	1187	tcphdr->chksum = 0;
darran	0:55a05330f8cc	1188	tcphdr->urgp = 0;
darran	0:55a05330f8cc	1189
darran	0:55a05330f8cc	1190	#if CHECKSUM_GEN_TCP
darran	0:55a05330f8cc	1191	tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
darran	0:55a05330f8cc	1192	IP_PROTO_TCP, p->tot_len);
darran	0:55a05330f8cc	1193	#endif
darran	0:55a05330f8cc	1194	TCP_STATS_INC(tcp.xmit);
darran	0:55a05330f8cc	1195	snmp_inc_tcpoutrsts();
darran	0:55a05330f8cc	1196	/* Send output with hardcoded TTL since we have no access to the pcb */
darran	0:55a05330f8cc	1197	ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
darran	0:55a05330f8cc	1198	pbuf_free(p);
darran	0:55a05330f8cc	1199	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
darran	0:55a05330f8cc	1200	}
darran	0:55a05330f8cc	1201
darran	0:55a05330f8cc	1202	/**
darran	0:55a05330f8cc	1203	* Requeue all unacked segments for retransmission
darran	0:55a05330f8cc	1204	*
darran	0:55a05330f8cc	1205	* Called by tcp_slowtmr() for slow retransmission.
darran	0:55a05330f8cc	1206	*
darran	0:55a05330f8cc	1207	* @param pcb the tcp_pcb for which to re-enqueue all unacked segments
darran	0:55a05330f8cc	1208	*/
darran	0:55a05330f8cc	1209	void
darran	0:55a05330f8cc	1210	tcp_rexmit_rto(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	1211	{
darran	0:55a05330f8cc	1212	struct tcp_seg *seg;
darran	0:55a05330f8cc	1213
darran	0:55a05330f8cc	1214	if (pcb->unacked == NULL) {
darran	0:55a05330f8cc	1215	return;
darran	0:55a05330f8cc	1216	}
darran	0:55a05330f8cc	1217
darran	0:55a05330f8cc	1218	/* Move all unacked segments to the head of the unsent queue */
darran	0:55a05330f8cc	1219	for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
darran	0:55a05330f8cc	1220	/* concatenate unsent queue after unacked queue */
darran	0:55a05330f8cc	1221	seg->next = pcb->unsent;
darran	0:55a05330f8cc	1222	/* unsent queue is the concatenated queue (of unacked, unsent) */
darran	0:55a05330f8cc	1223	pcb->unsent = pcb->unacked;
darran	0:55a05330f8cc	1224	/* unacked queue is now empty */
darran	0:55a05330f8cc	1225	pcb->unacked = NULL;
darran	0:55a05330f8cc	1226
darran	0:55a05330f8cc	1227	/* increment number of retransmissions */
darran	0:55a05330f8cc	1228	++pcb->nrtx;
darran	0:55a05330f8cc	1229
darran	0:55a05330f8cc	1230	/* Don't take any RTT measurements after retransmitting. */
darran	0:55a05330f8cc	1231	pcb->rttest = 0;
darran	0:55a05330f8cc	1232
darran	0:55a05330f8cc	1233	/* Do the actual retransmission */
darran	0:55a05330f8cc	1234	tcp_output(pcb);
darran	0:55a05330f8cc	1235	}
darran	0:55a05330f8cc	1236
darran	0:55a05330f8cc	1237	/**
darran	0:55a05330f8cc	1238	* Requeue the first unacked segment for retransmission
darran	0:55a05330f8cc	1239	*
darran	0:55a05330f8cc	1240	* Called by tcp_receive() for fast retramsmit.
darran	0:55a05330f8cc	1241	*
darran	0:55a05330f8cc	1242	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
darran	0:55a05330f8cc	1243	*/
darran	0:55a05330f8cc	1244	void
darran	0:55a05330f8cc	1245	tcp_rexmit(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	1246	{
darran	0:55a05330f8cc	1247	struct tcp_seg *seg;
darran	0:55a05330f8cc	1248	struct tcp_seg **cur_seg;
darran	0:55a05330f8cc	1249
darran	0:55a05330f8cc	1250	if (pcb->unacked == NULL) {
darran	0:55a05330f8cc	1251	return;
darran	0:55a05330f8cc	1252	}
darran	0:55a05330f8cc	1253
darran	0:55a05330f8cc	1254	/* Move the first unacked segment to the unsent queue */
darran	0:55a05330f8cc	1255	/* Keep the unsent queue sorted. */
darran	0:55a05330f8cc	1256	seg = pcb->unacked;
darran	0:55a05330f8cc	1257	pcb->unacked = seg->next;
darran	0:55a05330f8cc	1258
darran	0:55a05330f8cc	1259	cur_seg = &(pcb->unsent);
darran	0:55a05330f8cc	1260	while (*cur_seg &&
darran	0:55a05330f8cc	1261	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
darran	0:55a05330f8cc	1262	cur_seg = &((*cur_seg)->next );
darran	0:55a05330f8cc	1263	}
darran	0:55a05330f8cc	1264	seg->next = *cur_seg;
darran	0:55a05330f8cc	1265	*cur_seg = seg;
darran	0:55a05330f8cc	1266
darran	0:55a05330f8cc	1267	++pcb->nrtx;
darran	0:55a05330f8cc	1268
darran	0:55a05330f8cc	1269	/* Don't take any rtt measurements after retransmitting. */
darran	0:55a05330f8cc	1270	pcb->rttest = 0;
darran	0:55a05330f8cc	1271
darran	0:55a05330f8cc	1272	/* Do the actual retransmission. */
darran	0:55a05330f8cc	1273	snmp_inc_tcpretranssegs();
darran	0:55a05330f8cc	1274	/* No need to call tcp_output: we are always called from tcp_input()
darran	0:55a05330f8cc	1275	and thus tcp_output directly returns. */
darran	0:55a05330f8cc	1276	}
darran	0:55a05330f8cc	1277
darran	0:55a05330f8cc	1278
darran	0:55a05330f8cc	1279	/**
darran	0:55a05330f8cc	1280	* Handle retransmission after three dupacks received
darran	0:55a05330f8cc	1281	*
darran	0:55a05330f8cc	1282	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
darran	0:55a05330f8cc	1283	*/
darran	0:55a05330f8cc	1284	void
darran	0:55a05330f8cc	1285	tcp_rexmit_fast(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	1286	{
darran	0:55a05330f8cc	1287	if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
darran	0:55a05330f8cc	1288	/* This is fast retransmit. Retransmit the first unacked segment. */
darran	0:55a05330f8cc	1289	LWIP_DEBUGF(TCP_FR_DEBUG,
darran	0:55a05330f8cc	1290	("tcp_receive: dupacks %"U16_F" (%"U32_F
darran	0:55a05330f8cc	1291	"), fast retransmit %"U32_F"\n",
darran	0:55a05330f8cc	1292	(u16_t)pcb->dupacks, pcb->lastack,
darran	0:55a05330f8cc	1293	ntohl(pcb->unacked->tcphdr->seqno)));
darran	0:55a05330f8cc	1294	tcp_rexmit(pcb);
darran	0:55a05330f8cc	1295
darran	0:55a05330f8cc	1296	/* Set ssthresh to half of the minimum of the current
darran	0:55a05330f8cc	1297	* cwnd and the advertised window */
darran	0:55a05330f8cc	1298	if (pcb->cwnd > pcb->snd_wnd) {
darran	0:55a05330f8cc	1299	pcb->ssthresh = pcb->snd_wnd / 2;
darran	0:55a05330f8cc	1300	} else {
darran	0:55a05330f8cc	1301	pcb->ssthresh = pcb->cwnd / 2;
darran	0:55a05330f8cc	1302	}
darran	0:55a05330f8cc	1303
darran	0:55a05330f8cc	1304	/* The minimum value for ssthresh should be 2 MSS */
darran	0:55a05330f8cc	1305	if (pcb->ssthresh < 2*pcb->mss) {
darran	0:55a05330f8cc	1306	LWIP_DEBUGF(TCP_FR_DEBUG,
darran	0:55a05330f8cc	1307	("tcp_receive: The minimum value for ssthresh %"U16_F
darran	0:55a05330f8cc	1308	" should be min 2 mss %"U16_F"...\n",
darran	0:55a05330f8cc	1309	pcb->ssthresh, 2*pcb->mss));
darran	0:55a05330f8cc	1310	pcb->ssthresh = 2*pcb->mss;
darran	0:55a05330f8cc	1311	}
darran	0:55a05330f8cc	1312
darran	0:55a05330f8cc	1313	pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
darran	0:55a05330f8cc	1314	pcb->flags \|= TF_INFR;
darran	0:55a05330f8cc	1315	}
darran	0:55a05330f8cc	1316	}
darran	0:55a05330f8cc	1317
darran	0:55a05330f8cc	1318
darran	0:55a05330f8cc	1319	/**
darran	0:55a05330f8cc	1320	* Send keepalive packets to keep a connection active although
darran	0:55a05330f8cc	1321	* no data is sent over it.
darran	0:55a05330f8cc	1322	*
darran	0:55a05330f8cc	1323	* Called by tcp_slowtmr()
darran	0:55a05330f8cc	1324	*
darran	0:55a05330f8cc	1325	* @param pcb the tcp_pcb for which to send a keepalive packet
darran	0:55a05330f8cc	1326	*/
darran	0:55a05330f8cc	1327	void
darran	0:55a05330f8cc	1328	tcp_keepalive(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	1329	{
darran	0:55a05330f8cc	1330	struct pbuf *p;
darran	0:55a05330f8cc	1331	struct tcp_hdr *tcphdr;
darran	0:55a05330f8cc	1332
darran	0:55a05330f8cc	1333	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
darran	0:55a05330f8cc	1334	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
darran	0:55a05330f8cc	1335	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
darran	0:55a05330f8cc	1336
darran	0:55a05330f8cc	1337	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
darran	0:55a05330f8cc	1338	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
darran	0:55a05330f8cc	1339
darran	0:55a05330f8cc	1340	p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
darran	0:55a05330f8cc	1341	if(p == NULL) {
darran	0:55a05330f8cc	1342	LWIP_DEBUGF(TCP_DEBUG,
darran	0:55a05330f8cc	1343	("tcp_keepalive: could not allocate memory for pbuf\n"));
darran	0:55a05330f8cc	1344	return;
darran	0:55a05330f8cc	1345	}
darran	0:55a05330f8cc	1346	tcphdr = (struct tcp_hdr *)p->payload;
darran	0:55a05330f8cc	1347
darran	0:55a05330f8cc	1348	#if CHECKSUM_GEN_TCP
darran	0:55a05330f8cc	1349	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
darran	0:55a05330f8cc	1350	IP_PROTO_TCP, p->tot_len);
darran	0:55a05330f8cc	1351	#endif
darran	0:55a05330f8cc	1352	TCP_STATS_INC(tcp.xmit);
darran	0:55a05330f8cc	1353
darran	0:55a05330f8cc	1354	/* Send output to IP */
darran	0:55a05330f8cc	1355	#if LWIP_NETIF_HWADDRHINT
darran	0:55a05330f8cc	1356	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
darran	0:55a05330f8cc	1357	&(pcb->addr_hint));
darran	0:55a05330f8cc	1358	#else /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	1359	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
darran	0:55a05330f8cc	1360	#endif /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	1361
darran	0:55a05330f8cc	1362	pbuf_free(p);
darran	0:55a05330f8cc	1363
darran	0:55a05330f8cc	1364	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
darran	0:55a05330f8cc	1365	pcb->snd_nxt - 1, pcb->rcv_nxt));
darran	0:55a05330f8cc	1366	}
darran	0:55a05330f8cc	1367
darran	0:55a05330f8cc	1368
darran	0:55a05330f8cc	1369	/**
darran	0:55a05330f8cc	1370	* Send persist timer zero-window probes to keep a connection active
darran	0:55a05330f8cc	1371	* when a window update is lost.
darran	0:55a05330f8cc	1372	*
darran	0:55a05330f8cc	1373	* Called by tcp_slowtmr()
darran	0:55a05330f8cc	1374	*
darran	0:55a05330f8cc	1375	* @param pcb the tcp_pcb for which to send a zero-window probe packet
darran	0:55a05330f8cc	1376	*/
darran	0:55a05330f8cc	1377	void
darran	0:55a05330f8cc	1378	tcp_zero_window_probe(struct tcp_pcb *pcb)
darran	0:55a05330f8cc	1379	{
darran	0:55a05330f8cc	1380	struct pbuf *p;
darran	0:55a05330f8cc	1381	struct tcp_hdr *tcphdr;
darran	0:55a05330f8cc	1382	struct tcp_seg *seg;
darran	0:55a05330f8cc	1383	u16_t len;
darran	0:55a05330f8cc	1384	u8_t is_fin;
darran	0:55a05330f8cc	1385
darran	0:55a05330f8cc	1386	LWIP_DEBUGF(TCP_DEBUG,
darran	0:55a05330f8cc	1387	("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
darran	0:55a05330f8cc	1388	U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
darran	0:55a05330f8cc	1389	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
darran	0:55a05330f8cc	1390	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
darran	0:55a05330f8cc	1391
darran	0:55a05330f8cc	1392	LWIP_DEBUGF(TCP_DEBUG,
darran	0:55a05330f8cc	1393	("tcp_zero_window_probe: tcp_ticks %"U32_F
darran	0:55a05330f8cc	1394	" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
darran	0:55a05330f8cc	1395	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
darran	0:55a05330f8cc	1396
darran	0:55a05330f8cc	1397	seg = pcb->unacked;
darran	0:55a05330f8cc	1398
darran	0:55a05330f8cc	1399	if(seg == NULL) {
darran	0:55a05330f8cc	1400	seg = pcb->unsent;
darran	0:55a05330f8cc	1401	}
darran	0:55a05330f8cc	1402	if(seg == NULL) {
darran	0:55a05330f8cc	1403	return;
darran	0:55a05330f8cc	1404	}
darran	0:55a05330f8cc	1405
darran	0:55a05330f8cc	1406	is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
darran	0:55a05330f8cc	1407	/* we want to send one seqno: either FIN or data (no options) */
darran	0:55a05330f8cc	1408	len = is_fin ? 0 : 1;
darran	0:55a05330f8cc	1409
darran	0:55a05330f8cc	1410	p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
darran	0:55a05330f8cc	1411	if(p == NULL) {
darran	0:55a05330f8cc	1412	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
darran	0:55a05330f8cc	1413	return;
darran	0:55a05330f8cc	1414	}
darran	0:55a05330f8cc	1415	tcphdr = (struct tcp_hdr *)p->payload;
darran	0:55a05330f8cc	1416
darran	0:55a05330f8cc	1417	if (is_fin) {
darran	0:55a05330f8cc	1418	/* FIN segment, no data */
darran	0:55a05330f8cc	1419	TCPH_FLAGS_SET(tcphdr, TCP_ACK \| TCP_FIN);
darran	0:55a05330f8cc	1420	} else {
darran	0:55a05330f8cc	1421	/* Data segment, copy in one byte from the head of the unacked queue */
darran	0:55a05330f8cc	1422	((char )p->payload + TCP_HLEN) = (char )seg->dataptr;
darran	0:55a05330f8cc	1423	}
darran	0:55a05330f8cc	1424
darran	0:55a05330f8cc	1425	#if CHECKSUM_GEN_TCP
darran	0:55a05330f8cc	1426	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
darran	0:55a05330f8cc	1427	IP_PROTO_TCP, p->tot_len);
darran	0:55a05330f8cc	1428	#endif
darran	0:55a05330f8cc	1429	TCP_STATS_INC(tcp.xmit);
darran	0:55a05330f8cc	1430
darran	0:55a05330f8cc	1431	/* Send output to IP */
darran	0:55a05330f8cc	1432	#if LWIP_NETIF_HWADDRHINT
darran	0:55a05330f8cc	1433	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
darran	0:55a05330f8cc	1434	&(pcb->addr_hint));
darran	0:55a05330f8cc	1435	#else /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	1436	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
darran	0:55a05330f8cc	1437	#endif /* LWIP_NETIF_HWADDRHINT*/
darran	0:55a05330f8cc	1438
darran	0:55a05330f8cc	1439	pbuf_free(p);
darran	0:55a05330f8cc	1440
darran	0:55a05330f8cc	1441	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
darran	0:55a05330f8cc	1442	" ackno %"U32_F".\n",
darran	0:55a05330f8cc	1443	pcb->snd_nxt - 1, pcb->rcv_nxt));
darran	0:55a05330f8cc	1444	}
darran	0:55a05330f8cc	1445	#endif /* LWIP_TCP */

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	18 Jun 2010
Imports:	7
Forks:	0
Commits:	2
Dependents:	0
Dependencies:	1
Followers:	1

lwip/core/tcp_out.c@1:4218cacaf696, 2010-06-18 (annotated)

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