NetServicesMod - Modified version of NetServices. Fixes an issue w…

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Modified version of NetServices. Fixes an issue where connections failed should the HTTP response status line be received in a packet on its own prior to any further headers. Changes are made to the HTTPClient.cpp file's readHeaders method.

lwip/core/tcp_out.c@0:ec559500a63f, 2011-04-08 (annotated)

Committer:: andrewbonney
Date:: Fri Apr 08 14:39:41 2011 +0000
Revision:: 0:ec559500a63f

Who changed what in which revision?

User	Revision	Line number	New contents of line
andrewbonney	0:ec559500a63f	1	/**
andrewbonney	0:ec559500a63f	2	* @file
andrewbonney	0:ec559500a63f	3	* Transmission Control Protocol, outgoing traffic
andrewbonney	0:ec559500a63f	4	*
andrewbonney	0:ec559500a63f	5	* The output functions of TCP.
andrewbonney	0:ec559500a63f	6	*
andrewbonney	0:ec559500a63f	7	*/
andrewbonney	0:ec559500a63f	8
andrewbonney	0:ec559500a63f	9	/*
andrewbonney	0:ec559500a63f	10	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
andrewbonney	0:ec559500a63f	11	* All rights reserved.
andrewbonney	0:ec559500a63f	12	*
andrewbonney	0:ec559500a63f	13	* Redistribution and use in source and binary forms, with or without modification,
andrewbonney	0:ec559500a63f	14	* are permitted provided that the following conditions are met:
andrewbonney	0:ec559500a63f	15	*
andrewbonney	0:ec559500a63f	16	* 1. Redistributions of source code must retain the above copyright notice,
andrewbonney	0:ec559500a63f	17	* this list of conditions and the following disclaimer.
andrewbonney	0:ec559500a63f	18	* 2. Redistributions in binary form must reproduce the above copyright notice,
andrewbonney	0:ec559500a63f	19	* this list of conditions and the following disclaimer in the documentation
andrewbonney	0:ec559500a63f	20	* and/or other materials provided with the distribution.
andrewbonney	0:ec559500a63f	21	* 3. The name of the author may not be used to endorse or promote products
andrewbonney	0:ec559500a63f	22	* derived from this software without specific prior written permission.
andrewbonney	0:ec559500a63f	23	*
andrewbonney	0:ec559500a63f	24	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
andrewbonney	0:ec559500a63f	25	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
andrewbonney	0:ec559500a63f	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
andrewbonney	0:ec559500a63f	27	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
andrewbonney	0:ec559500a63f	28	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
andrewbonney	0:ec559500a63f	29	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
andrewbonney	0:ec559500a63f	30	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
andrewbonney	0:ec559500a63f	31	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
andrewbonney	0:ec559500a63f	32	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
andrewbonney	0:ec559500a63f	33	* OF SUCH DAMAGE.
andrewbonney	0:ec559500a63f	34	*
andrewbonney	0:ec559500a63f	35	* This file is part of the lwIP TCP/IP stack.
andrewbonney	0:ec559500a63f	36	*
andrewbonney	0:ec559500a63f	37	* Author: Adam Dunkels <adam@sics.se>
andrewbonney	0:ec559500a63f	38	*
andrewbonney	0:ec559500a63f	39	*/
andrewbonney	0:ec559500a63f	40
andrewbonney	0:ec559500a63f	41	#include "lwip/opt.h"
andrewbonney	0:ec559500a63f	42
andrewbonney	0:ec559500a63f	43	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
andrewbonney	0:ec559500a63f	44
andrewbonney	0:ec559500a63f	45	#include "lwip/tcp_impl.h"
andrewbonney	0:ec559500a63f	46	#include "lwip/def.h"
andrewbonney	0:ec559500a63f	47	#include "lwip/mem.h"
andrewbonney	0:ec559500a63f	48	#include "lwip/memp.h"
andrewbonney	0:ec559500a63f	49	#include "lwip/sys.h"
andrewbonney	0:ec559500a63f	50	#include "lwip/ip_addr.h"
andrewbonney	0:ec559500a63f	51	#include "lwip/netif.h"
andrewbonney	0:ec559500a63f	52	#include "lwip/inet_chksum.h"
andrewbonney	0:ec559500a63f	53	#include "lwip/stats.h"
andrewbonney	0:ec559500a63f	54	#include "lwip/snmp.h"
andrewbonney	0:ec559500a63f	55
andrewbonney	0:ec559500a63f	56	#include <string.h>
andrewbonney	0:ec559500a63f	57
andrewbonney	0:ec559500a63f	58	/* Define some copy-macros for checksum-on-copy so that the code looks
andrewbonney	0:ec559500a63f	59	nicer by preventing too many ifdef's. */
andrewbonney	0:ec559500a63f	60	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	61	#define TCP_DATA_COPY(dst, src, len, seg) do { \
andrewbonney	0:ec559500a63f	62	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
andrewbonney	0:ec559500a63f	63	len, &seg->chksum, &seg->chksum_swapped); \
andrewbonney	0:ec559500a63f	64	seg->flags \|= TF_SEG_DATA_CHECKSUMMED; } while(0)
andrewbonney	0:ec559500a63f	65	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
andrewbonney	0:ec559500a63f	66	tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
andrewbonney	0:ec559500a63f	67	#else /* TCP_CHECKSUM_ON_COPY*/
andrewbonney	0:ec559500a63f	68	#define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
andrewbonney	0:ec559500a63f	69	#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
andrewbonney	0:ec559500a63f	70	#endif /* TCP_CHECKSUM_ON_COPY*/
andrewbonney	0:ec559500a63f	71
andrewbonney	0:ec559500a63f	72	/** Define this to 1 for an extra check that the output checksum is valid
andrewbonney	0:ec559500a63f	73	* (usefule when the checksum is generated by the application, not the stack) */
andrewbonney	0:ec559500a63f	74	#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
andrewbonney	0:ec559500a63f	75	#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
andrewbonney	0:ec559500a63f	76	#endif
andrewbonney	0:ec559500a63f	77
andrewbonney	0:ec559500a63f	78	/* Forward declarations.*/
andrewbonney	0:ec559500a63f	79	static void tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb);
andrewbonney	0:ec559500a63f	80
andrewbonney	0:ec559500a63f	81	/** Allocate a pbuf and create a tcphdr at p->payload, used for output
andrewbonney	0:ec559500a63f	82	* functions other than the default tcp_output -> tcp_output_segment
andrewbonney	0:ec559500a63f	83	* (e.g. tcp_send_empty_ack, etc.)
andrewbonney	0:ec559500a63f	84	*
andrewbonney	0:ec559500a63f	85	* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
andrewbonney	0:ec559500a63f	86	* @param optlen length of header-options
andrewbonney	0:ec559500a63f	87	* @param datalen length of tcp data to reserve in pbuf
andrewbonney	0:ec559500a63f	88	* @param seqno_be seqno in network byte order (big-endian)
andrewbonney	0:ec559500a63f	89	* @return pbuf with p->payload being the tcp_hdr
andrewbonney	0:ec559500a63f	90	*/
andrewbonney	0:ec559500a63f	91	static struct pbuf *
andrewbonney	0:ec559500a63f	92	tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
andrewbonney	0:ec559500a63f	93	u32_t seqno_be /* already in network byte order */)
andrewbonney	0:ec559500a63f	94	{
andrewbonney	0:ec559500a63f	95	struct tcp_hdr *tcphdr;
andrewbonney	0:ec559500a63f	96	struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
andrewbonney	0:ec559500a63f	97	if (p != NULL) {
andrewbonney	0:ec559500a63f	98	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
andrewbonney	0:ec559500a63f	99	(p->len >= TCP_HLEN + optlen));
andrewbonney	0:ec559500a63f	100	tcphdr = (struct tcp_hdr *)p->payload;
andrewbonney	0:ec559500a63f	101	tcphdr->src = htons(pcb->local_port);
andrewbonney	0:ec559500a63f	102	tcphdr->dest = htons(pcb->remote_port);
andrewbonney	0:ec559500a63f	103	tcphdr->seqno = seqno_be;
andrewbonney	0:ec559500a63f	104	tcphdr->ackno = htonl(pcb->rcv_nxt);
andrewbonney	0:ec559500a63f	105	TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
andrewbonney	0:ec559500a63f	106	tcphdr->wnd = htons(pcb->rcv_ann_wnd);
andrewbonney	0:ec559500a63f	107	tcphdr->chksum = 0;
andrewbonney	0:ec559500a63f	108	tcphdr->urgp = 0;
andrewbonney	0:ec559500a63f	109
andrewbonney	0:ec559500a63f	110	/* If we're sending a packet, update the announced right window edge */
andrewbonney	0:ec559500a63f	111	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
andrewbonney	0:ec559500a63f	112	}
andrewbonney	0:ec559500a63f	113	return p;
andrewbonney	0:ec559500a63f	114	}
andrewbonney	0:ec559500a63f	115
andrewbonney	0:ec559500a63f	116	/**
andrewbonney	0:ec559500a63f	117	* Called by tcp_close() to send a segment including FIN flag but not data.
andrewbonney	0:ec559500a63f	118	*
andrewbonney	0:ec559500a63f	119	* @param pcb the tcp_pcb over which to send a segment
andrewbonney	0:ec559500a63f	120	* @return ERR_OK if sent, another err_t otherwise
andrewbonney	0:ec559500a63f	121	*/
andrewbonney	0:ec559500a63f	122	err_t
andrewbonney	0:ec559500a63f	123	tcp_send_fin(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	124	{
andrewbonney	0:ec559500a63f	125	/* first, try to add the fin to the last unsent segment */
andrewbonney	0:ec559500a63f	126	if (pcb->unsent != NULL) {
andrewbonney	0:ec559500a63f	127	struct tcp_seg *last_unsent;
andrewbonney	0:ec559500a63f	128	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
andrewbonney	0:ec559500a63f	129	last_unsent = last_unsent->next);
andrewbonney	0:ec559500a63f	130
andrewbonney	0:ec559500a63f	131	if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN \| TCP_FIN \| TCP_RST)) == 0) {
andrewbonney	0:ec559500a63f	132	/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
andrewbonney	0:ec559500a63f	133	TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
andrewbonney	0:ec559500a63f	134	return ERR_OK;
andrewbonney	0:ec559500a63f	135	}
andrewbonney	0:ec559500a63f	136	}
andrewbonney	0:ec559500a63f	137	/* no data, no length, flags, copy=1, no optdata */
andrewbonney	0:ec559500a63f	138	return tcp_enqueue_flags(pcb, TCP_FIN);
andrewbonney	0:ec559500a63f	139	}
andrewbonney	0:ec559500a63f	140
andrewbonney	0:ec559500a63f	141	/**
andrewbonney	0:ec559500a63f	142	* Create a TCP segment with prefilled header.
andrewbonney	0:ec559500a63f	143	*
andrewbonney	0:ec559500a63f	144	* Called by tcp_write and tcp_enqueue_flags.
andrewbonney	0:ec559500a63f	145	*
andrewbonney	0:ec559500a63f	146	* @param pcb Protocol control block for the TCP connection.
andrewbonney	0:ec559500a63f	147	* @param p pbuf that is used to hold the TCP header.
andrewbonney	0:ec559500a63f	148	* @param flags TCP flags for header.
andrewbonney	0:ec559500a63f	149	* @param seqno TCP sequence number of this packet
andrewbonney	0:ec559500a63f	150	* @param optflags options to include in TCP header
andrewbonney	0:ec559500a63f	151	* @return a new tcp_seg pointing to p, or NULL.
andrewbonney	0:ec559500a63f	152	* The TCP header is filled in except ackno and wnd.
andrewbonney	0:ec559500a63f	153	* p is freed on failure.
andrewbonney	0:ec559500a63f	154	*/
andrewbonney	0:ec559500a63f	155	static struct tcp_seg *
andrewbonney	0:ec559500a63f	156	tcp_create_segment(struct tcp_pcb pcb, struct pbuf p, u8_t flags, u32_t seqno, u8_t optflags)
andrewbonney	0:ec559500a63f	157	{
andrewbonney	0:ec559500a63f	158	struct tcp_seg *seg;
andrewbonney	0:ec559500a63f	159	u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
andrewbonney	0:ec559500a63f	160
andrewbonney	0:ec559500a63f	161	if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
andrewbonney	0:ec559500a63f	162	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no memory.\n"));
andrewbonney	0:ec559500a63f	163	pbuf_free(p);
andrewbonney	0:ec559500a63f	164	return NULL;
andrewbonney	0:ec559500a63f	165	}
andrewbonney	0:ec559500a63f	166	seg->flags = optflags;
andrewbonney	0:ec559500a63f	167	seg->next = NULL;
andrewbonney	0:ec559500a63f	168	seg->p = p;
andrewbonney	0:ec559500a63f	169	seg->dataptr = p->payload;
andrewbonney	0:ec559500a63f	170	seg->len = p->tot_len - optlen;
andrewbonney	0:ec559500a63f	171	#if TCP_OVERSIZE_DBGCHECK
andrewbonney	0:ec559500a63f	172	seg->oversize_left = 0;
andrewbonney	0:ec559500a63f	173	#endif /* TCP_OVERSIZE_DBGCHECK */
andrewbonney	0:ec559500a63f	174	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	175	seg->chksum = 0;
andrewbonney	0:ec559500a63f	176	seg->chksum_swapped = 0;
andrewbonney	0:ec559500a63f	177	/* check optflags */
andrewbonney	0:ec559500a63f	178	LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
andrewbonney	0:ec559500a63f	179	(optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
andrewbonney	0:ec559500a63f	180	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	181
andrewbonney	0:ec559500a63f	182	/* build TCP header */
andrewbonney	0:ec559500a63f	183	if (pbuf_header(p, TCP_HLEN)) {
andrewbonney	0:ec559500a63f	184	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
andrewbonney	0:ec559500a63f	185	TCP_STATS_INC(tcp.err);
andrewbonney	0:ec559500a63f	186	tcp_seg_free(seg);
andrewbonney	0:ec559500a63f	187	return NULL;
andrewbonney	0:ec559500a63f	188	}
andrewbonney	0:ec559500a63f	189	seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
andrewbonney	0:ec559500a63f	190	seg->tcphdr->src = htons(pcb->local_port);
andrewbonney	0:ec559500a63f	191	seg->tcphdr->dest = htons(pcb->remote_port);
andrewbonney	0:ec559500a63f	192	seg->tcphdr->seqno = htonl(seqno);
andrewbonney	0:ec559500a63f	193	/* ackno is set in tcp_output */
andrewbonney	0:ec559500a63f	194	TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
andrewbonney	0:ec559500a63f	195	/* wnd and chksum are set in tcp_output */
andrewbonney	0:ec559500a63f	196	seg->tcphdr->urgp = 0;
andrewbonney	0:ec559500a63f	197	return seg;
andrewbonney	0:ec559500a63f	198	}
andrewbonney	0:ec559500a63f	199
andrewbonney	0:ec559500a63f	200	/**
andrewbonney	0:ec559500a63f	201	* Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
andrewbonney	0:ec559500a63f	202	*
andrewbonney	0:ec559500a63f	203	* This function is like pbuf_alloc(layer, length, PBUF_RAM) except
andrewbonney	0:ec559500a63f	204	* there may be extra bytes available at the end.
andrewbonney	0:ec559500a63f	205	*
andrewbonney	0:ec559500a63f	206	* @param layer flag to define header size.
andrewbonney	0:ec559500a63f	207	* @param length size of the pbuf's payload.
andrewbonney	0:ec559500a63f	208	* @param max_length maximum usable size of payload+oversize.
andrewbonney	0:ec559500a63f	209	* @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
andrewbonney	0:ec559500a63f	210	* @param pcb The TCP connection that willo enqueue the pbuf.
andrewbonney	0:ec559500a63f	211	* @param apiflags API flags given to tcp_write.
andrewbonney	0:ec559500a63f	212	* @param first_seg true when this pbuf will be used in the first enqueued segment.
andrewbonney	0:ec559500a63f	213	* @param
andrewbonney	0:ec559500a63f	214	*/
andrewbonney	0:ec559500a63f	215	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	216	static struct pbuf *
andrewbonney	0:ec559500a63f	217	tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
andrewbonney	0:ec559500a63f	218	u16_t oversize, struct tcp_pcb pcb, u8_t apiflags,
andrewbonney	0:ec559500a63f	219	u8_t first_seg)
andrewbonney	0:ec559500a63f	220	{
andrewbonney	0:ec559500a63f	221	struct pbuf *p;
andrewbonney	0:ec559500a63f	222	u16_t alloc = length;
andrewbonney	0:ec559500a63f	223
andrewbonney	0:ec559500a63f	224	#if LWIP_NETIF_TX_SINGLE_PBUF
andrewbonney	0:ec559500a63f	225	LWIP_UNUSED_ARG(max_length);
andrewbonney	0:ec559500a63f	226	LWIP_UNUSED_ARG(pcb);
andrewbonney	0:ec559500a63f	227	LWIP_UNUSED_ARG(apiflags);
andrewbonney	0:ec559500a63f	228	LWIP_UNUSED_ARG(first_seg);
andrewbonney	0:ec559500a63f	229	/* always create MSS-sized pbufs */
andrewbonney	0:ec559500a63f	230	alloc = TCP_MSS;
andrewbonney	0:ec559500a63f	231	#else /* LWIP_NETIF_TX_SINGLE_PBUF */
andrewbonney	0:ec559500a63f	232	if (length < max_length) {
andrewbonney	0:ec559500a63f	233	/* Should we allocate an oversized pbuf, or just the minimum
andrewbonney	0:ec559500a63f	234	* length required? If tcp_write is going to be called again
andrewbonney	0:ec559500a63f	235	* before this segment is transmitted, we want the oversized
andrewbonney	0:ec559500a63f	236	* buffer. If the segment will be transmitted immediately, we can
andrewbonney	0:ec559500a63f	237	* save memory by allocating only length. We use a simple
andrewbonney	0:ec559500a63f	238	* heuristic based on the following information:
andrewbonney	0:ec559500a63f	239	*
andrewbonney	0:ec559500a63f	240	* Did the user set TCP_WRITE_FLAG_MORE?
andrewbonney	0:ec559500a63f	241	*
andrewbonney	0:ec559500a63f	242	* Will the Nagle algorithm defer transmission of this segment?
andrewbonney	0:ec559500a63f	243	*/
andrewbonney	0:ec559500a63f	244	if ((apiflags & TCP_WRITE_FLAG_MORE) \|\|
andrewbonney	0:ec559500a63f	245	(!(pcb->flags & TF_NODELAY) &&
andrewbonney	0:ec559500a63f	246	(!first_seg \|\|
andrewbonney	0:ec559500a63f	247	pcb->unsent != NULL \|\|
andrewbonney	0:ec559500a63f	248	pcb->unacked != NULL))) {
andrewbonney	0:ec559500a63f	249	alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
andrewbonney	0:ec559500a63f	250	}
andrewbonney	0:ec559500a63f	251	}
andrewbonney	0:ec559500a63f	252	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
andrewbonney	0:ec559500a63f	253	p = pbuf_alloc(layer, alloc, PBUF_RAM);
andrewbonney	0:ec559500a63f	254	if (p == NULL) {
andrewbonney	0:ec559500a63f	255	return NULL;
andrewbonney	0:ec559500a63f	256	}
andrewbonney	0:ec559500a63f	257	LWIP_ASSERT("need unchained pbuf", p->next == NULL);
andrewbonney	0:ec559500a63f	258	*oversize = p->len - length;
andrewbonney	0:ec559500a63f	259	/* trim p->len to the currently used size */
andrewbonney	0:ec559500a63f	260	p->len = p->tot_len = length;
andrewbonney	0:ec559500a63f	261	return p;
andrewbonney	0:ec559500a63f	262	}
andrewbonney	0:ec559500a63f	263	#else /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	264	#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
andrewbonney	0:ec559500a63f	265	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	266
andrewbonney	0:ec559500a63f	267	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	268	/** Add a checksum of newly added data to the segment */
andrewbonney	0:ec559500a63f	269	static void
andrewbonney	0:ec559500a63f	270	tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
andrewbonney	0:ec559500a63f	271	u8_t *seg_chksum_swapped)
andrewbonney	0:ec559500a63f	272	{
andrewbonney	0:ec559500a63f	273	u32_t helper;
andrewbonney	0:ec559500a63f	274	/* add chksum to old chksum and fold to u16_t */
andrewbonney	0:ec559500a63f	275	helper = chksum + *seg_chksum;
andrewbonney	0:ec559500a63f	276	chksum = FOLD_U32T(helper);
andrewbonney	0:ec559500a63f	277	if ((len & 1) != 0) {
andrewbonney	0:ec559500a63f	278	seg_chksum_swapped = 1 - seg_chksum_swapped;
andrewbonney	0:ec559500a63f	279	chksum = SWAP_BYTES_IN_WORD(chksum);
andrewbonney	0:ec559500a63f	280	}
andrewbonney	0:ec559500a63f	281	*seg_chksum = chksum;
andrewbonney	0:ec559500a63f	282	}
andrewbonney	0:ec559500a63f	283	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	284
andrewbonney	0:ec559500a63f	285	/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
andrewbonney	0:ec559500a63f	286	*
andrewbonney	0:ec559500a63f	287	* @param pcb the tcp pcb to check for
andrewbonney	0:ec559500a63f	288	* @param len length of data to send (checked agains snd_buf)
andrewbonney	0:ec559500a63f	289	* @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
andrewbonney	0:ec559500a63f	290	*/
andrewbonney	0:ec559500a63f	291	static err_t
andrewbonney	0:ec559500a63f	292	tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
andrewbonney	0:ec559500a63f	293	{
andrewbonney	0:ec559500a63f	294	/* connection is in invalid state for data transmission? */
andrewbonney	0:ec559500a63f	295	if ((pcb->state != ESTABLISHED) &&
andrewbonney	0:ec559500a63f	296	(pcb->state != CLOSE_WAIT) &&
andrewbonney	0:ec559500a63f	297	(pcb->state != SYN_SENT) &&
andrewbonney	0:ec559500a63f	298	(pcb->state != SYN_RCVD)) {
andrewbonney	0:ec559500a63f	299	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_STATE \| LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
andrewbonney	0:ec559500a63f	300	return ERR_CONN;
andrewbonney	0:ec559500a63f	301	} else if (len == 0) {
andrewbonney	0:ec559500a63f	302	return ERR_OK;
andrewbonney	0:ec559500a63f	303	}
andrewbonney	0:ec559500a63f	304
andrewbonney	0:ec559500a63f	305	/* fail on too much data */
andrewbonney	0:ec559500a63f	306	if (len > pcb->snd_buf) {
andrewbonney	0:ec559500a63f	307	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
andrewbonney	0:ec559500a63f	308	len, pcb->snd_buf));
andrewbonney	0:ec559500a63f	309	pcb->flags \|= TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	310	return ERR_MEM;
andrewbonney	0:ec559500a63f	311	}
andrewbonney	0:ec559500a63f	312
andrewbonney	0:ec559500a63f	313	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	314
andrewbonney	0:ec559500a63f	315	/* If total number of pbufs on the unsent/unacked queues exceeds the
andrewbonney	0:ec559500a63f	316	* configured maximum, return an error */
andrewbonney	0:ec559500a63f	317	/* check for configured max queuelen and possible overflow */
andrewbonney	0:ec559500a63f	318	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
andrewbonney	0:ec559500a63f	319	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
andrewbonney	0:ec559500a63f	320	pcb->snd_queuelen, TCP_SND_QUEUELEN));
andrewbonney	0:ec559500a63f	321	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	322	pcb->flags \|= TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	323	return ERR_MEM;
andrewbonney	0:ec559500a63f	324	}
andrewbonney	0:ec559500a63f	325	if (pcb->snd_queuelen != 0) {
andrewbonney	0:ec559500a63f	326	LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
andrewbonney	0:ec559500a63f	327	pcb->unacked != NULL \|\| pcb->unsent != NULL);
andrewbonney	0:ec559500a63f	328	} else {
andrewbonney	0:ec559500a63f	329	LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
andrewbonney	0:ec559500a63f	330	pcb->unacked == NULL && pcb->unsent == NULL);
andrewbonney	0:ec559500a63f	331	}
andrewbonney	0:ec559500a63f	332	return ERR_OK;
andrewbonney	0:ec559500a63f	333	}
andrewbonney	0:ec559500a63f	334
andrewbonney	0:ec559500a63f	335	/**
andrewbonney	0:ec559500a63f	336	* Write data for sending (but does not send it immediately).
andrewbonney	0:ec559500a63f	337	*
andrewbonney	0:ec559500a63f	338	* It waits in the expectation of more data being sent soon (as
andrewbonney	0:ec559500a63f	339	* it can send them more efficiently by combining them together).
andrewbonney	0:ec559500a63f	340	* To prompt the system to send data now, call tcp_output() after
andrewbonney	0:ec559500a63f	341	* calling tcp_write().
andrewbonney	0:ec559500a63f	342	*
andrewbonney	0:ec559500a63f	343	* @param pcb Protocol control block for the TCP connection to enqueue data for.
andrewbonney	0:ec559500a63f	344	* @param arg Pointer to the data to be enqueued for sending.
andrewbonney	0:ec559500a63f	345	* @param len Data length in bytes
andrewbonney	0:ec559500a63f	346	* @param apiflags combination of following flags :
andrewbonney	0:ec559500a63f	347	* - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
andrewbonney	0:ec559500a63f	348	* - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
andrewbonney	0:ec559500a63f	349	* @return ERR_OK if enqueued, another err_t on error
andrewbonney	0:ec559500a63f	350	*/
andrewbonney	0:ec559500a63f	351	err_t
andrewbonney	0:ec559500a63f	352	tcp_write(struct tcp_pcb pcb, const void arg, u16_t len, u8_t apiflags)
andrewbonney	0:ec559500a63f	353	{
andrewbonney	0:ec559500a63f	354	struct pbuf *concat_p = NULL;
andrewbonney	0:ec559500a63f	355	struct tcp_seg last_unsent = NULL, seg = NULL, prev_seg = NULL, queue = NULL;
andrewbonney	0:ec559500a63f	356	u16_t pos = 0; /* position in 'arg' data */
andrewbonney	0:ec559500a63f	357	u16_t queuelen;
andrewbonney	0:ec559500a63f	358	u8_t optlen = 0;
andrewbonney	0:ec559500a63f	359	u8_t optflags = 0;
andrewbonney	0:ec559500a63f	360	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	361	u16_t oversize = 0;
andrewbonney	0:ec559500a63f	362	u16_t oversize_used = 0;
andrewbonney	0:ec559500a63f	363	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	364	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	365	u16_t concat_chksum = 0;
andrewbonney	0:ec559500a63f	366	u8_t concat_chksum_swapped = 0;
andrewbonney	0:ec559500a63f	367	u16_t concat_chksummed = 0;
andrewbonney	0:ec559500a63f	368	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	369	err_t err;
andrewbonney	0:ec559500a63f	370
andrewbonney	0:ec559500a63f	371	#if LWIP_NETIF_TX_SINGLE_PBUF
andrewbonney	0:ec559500a63f	372	/* Always copy to try to create single pbufs for TX */
andrewbonney	0:ec559500a63f	373	apiflags \|= TCP_WRITE_FLAG_COPY;
andrewbonney	0:ec559500a63f	374	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
andrewbonney	0:ec559500a63f	375
andrewbonney	0:ec559500a63f	376	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
andrewbonney	0:ec559500a63f	377	(void *)pcb, arg, len, (u16_t)apiflags));
andrewbonney	0:ec559500a63f	378	LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
andrewbonney	0:ec559500a63f	379	arg != NULL, return ERR_ARG;);
andrewbonney	0:ec559500a63f	380
andrewbonney	0:ec559500a63f	381	err = tcp_write_checks(pcb, len);
andrewbonney	0:ec559500a63f	382	if (err != ERR_OK) {
andrewbonney	0:ec559500a63f	383	return err;
andrewbonney	0:ec559500a63f	384	}
andrewbonney	0:ec559500a63f	385	queuelen = pcb->snd_queuelen;
andrewbonney	0:ec559500a63f	386
andrewbonney	0:ec559500a63f	387	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	388	if ((pcb->flags & TF_TIMESTAMP)) {
andrewbonney	0:ec559500a63f	389	optflags = TF_SEG_OPTS_TS;
andrewbonney	0:ec559500a63f	390	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
andrewbonney	0:ec559500a63f	391	}
andrewbonney	0:ec559500a63f	392	#endif /* LWIP_TCP_TIMESTAMPS */
andrewbonney	0:ec559500a63f	393
andrewbonney	0:ec559500a63f	394
andrewbonney	0:ec559500a63f	395	/*
andrewbonney	0:ec559500a63f	396	* TCP segmentation is done in three phases with increasing complexity:
andrewbonney	0:ec559500a63f	397	*
andrewbonney	0:ec559500a63f	398	* 1. Copy data directly into an oversized pbuf.
andrewbonney	0:ec559500a63f	399	* 2. Chain a new pbuf to the end of pcb->unsent.
andrewbonney	0:ec559500a63f	400	* 3. Create new segments.
andrewbonney	0:ec559500a63f	401	*
andrewbonney	0:ec559500a63f	402	* We may run out of memory at any point. In that case we must
andrewbonney	0:ec559500a63f	403	* return ERR_MEM and not change anything in pcb. Therefore, all
andrewbonney	0:ec559500a63f	404	* changes are recorded in local variables and committed at the end
andrewbonney	0:ec559500a63f	405	* of the function. Some pcb fields are maintained in local copies:
andrewbonney	0:ec559500a63f	406	*
andrewbonney	0:ec559500a63f	407	* queuelen = pcb->snd_queuelen
andrewbonney	0:ec559500a63f	408	* oversize = pcb->unsent_oversize
andrewbonney	0:ec559500a63f	409	*
andrewbonney	0:ec559500a63f	410	* These variables are set consistently by the phases:
andrewbonney	0:ec559500a63f	411	*
andrewbonney	0:ec559500a63f	412	* seg points to the last segment tampered with.
andrewbonney	0:ec559500a63f	413	*
andrewbonney	0:ec559500a63f	414	* pos records progress as data is segmented.
andrewbonney	0:ec559500a63f	415	*/
andrewbonney	0:ec559500a63f	416
andrewbonney	0:ec559500a63f	417	/* Find the tail of the unsent queue. */
andrewbonney	0:ec559500a63f	418	if (pcb->unsent != NULL) {
andrewbonney	0:ec559500a63f	419	u16_t space;
andrewbonney	0:ec559500a63f	420	u16_t unsent_optlen;
andrewbonney	0:ec559500a63f	421
andrewbonney	0:ec559500a63f	422	/* @todo: this could be sped up by keeping last_unsent in the pcb */
andrewbonney	0:ec559500a63f	423	for (last_unsent = pcb->unsent; last_unsent->next != NULL;
andrewbonney	0:ec559500a63f	424	last_unsent = last_unsent->next);
andrewbonney	0:ec559500a63f	425
andrewbonney	0:ec559500a63f	426	/* Usable space at the end of the last unsent segment */
andrewbonney	0:ec559500a63f	427	unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
andrewbonney	0:ec559500a63f	428	space = pcb->mss - (last_unsent->len + unsent_optlen);
andrewbonney	0:ec559500a63f	429
andrewbonney	0:ec559500a63f	430	/*
andrewbonney	0:ec559500a63f	431	* Phase 1: Copy data directly into an oversized pbuf.
andrewbonney	0:ec559500a63f	432	*
andrewbonney	0:ec559500a63f	433	* The number of bytes copied is recorded in the oversize_used
andrewbonney	0:ec559500a63f	434	* variable. The actual copying is done at the bottom of the
andrewbonney	0:ec559500a63f	435	* function.
andrewbonney	0:ec559500a63f	436	*/
andrewbonney	0:ec559500a63f	437	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	438	#if TCP_OVERSIZE_DBGCHECK
andrewbonney	0:ec559500a63f	439	/* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
andrewbonney	0:ec559500a63f	440	LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
andrewbonney	0:ec559500a63f	441	pcb->unsent_oversize == last_unsent->oversize_left);
andrewbonney	0:ec559500a63f	442	#endif /* TCP_OVERSIZE_DBGCHECK */
andrewbonney	0:ec559500a63f	443	oversize = pcb->unsent_oversize;
andrewbonney	0:ec559500a63f	444	if (oversize > 0) {
andrewbonney	0:ec559500a63f	445	LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
andrewbonney	0:ec559500a63f	446	seg = last_unsent;
andrewbonney	0:ec559500a63f	447	oversize_used = oversize < len ? oversize : len;
andrewbonney	0:ec559500a63f	448	pos += oversize_used;
andrewbonney	0:ec559500a63f	449	oversize -= oversize_used;
andrewbonney	0:ec559500a63f	450	space -= oversize_used;
andrewbonney	0:ec559500a63f	451	}
andrewbonney	0:ec559500a63f	452	/* now we are either finished or oversize is zero */
andrewbonney	0:ec559500a63f	453	LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) \|\| (pos == len));
andrewbonney	0:ec559500a63f	454	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	455
andrewbonney	0:ec559500a63f	456	/*
andrewbonney	0:ec559500a63f	457	* Phase 2: Chain a new pbuf to the end of pcb->unsent.
andrewbonney	0:ec559500a63f	458	*
andrewbonney	0:ec559500a63f	459	* We don't extend segments containing SYN/FIN flags or options
andrewbonney	0:ec559500a63f	460	* (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
andrewbonney	0:ec559500a63f	461	* the end.
andrewbonney	0:ec559500a63f	462	*/
andrewbonney	0:ec559500a63f	463	if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
andrewbonney	0:ec559500a63f	464	u16_t seglen = space < len - pos ? space : len - pos;
andrewbonney	0:ec559500a63f	465	seg = last_unsent;
andrewbonney	0:ec559500a63f	466
andrewbonney	0:ec559500a63f	467	/* Create a pbuf with a copy or reference to seglen bytes. We
andrewbonney	0:ec559500a63f	468	* can use PBUF_RAW here since the data appears in the middle of
andrewbonney	0:ec559500a63f	469	* a segment. A header will never be prepended. */
andrewbonney	0:ec559500a63f	470	if (apiflags & TCP_WRITE_FLAG_COPY) {
andrewbonney	0:ec559500a63f	471	/* Data is copied */
andrewbonney	0:ec559500a63f	472	if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
andrewbonney	0:ec559500a63f	473	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
andrewbonney	0:ec559500a63f	474	("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
andrewbonney	0:ec559500a63f	475	seglen));
andrewbonney	0:ec559500a63f	476	goto memerr;
andrewbonney	0:ec559500a63f	477	}
andrewbonney	0:ec559500a63f	478	#if TCP_OVERSIZE_DBGCHECK
andrewbonney	0:ec559500a63f	479	last_unsent->oversize_left = oversize;
andrewbonney	0:ec559500a63f	480	#endif /* TCP_OVERSIZE_DBGCHECK */
andrewbonney	0:ec559500a63f	481	TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
andrewbonney	0:ec559500a63f	482	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	483	concat_chksummed += seglen;
andrewbonney	0:ec559500a63f	484	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	485	} else {
andrewbonney	0:ec559500a63f	486	/* Data is not copied */
andrewbonney	0:ec559500a63f	487	if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
andrewbonney	0:ec559500a63f	488	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2,
andrewbonney	0:ec559500a63f	489	("tcp_write: could not allocate memory for zero-copy pbuf\n"));
andrewbonney	0:ec559500a63f	490	goto memerr;
andrewbonney	0:ec559500a63f	491	}
andrewbonney	0:ec559500a63f	492	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	493	/* calculate the checksum of nocopy-data */
andrewbonney	0:ec559500a63f	494	tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
andrewbonney	0:ec559500a63f	495	&concat_chksum, &concat_chksum_swapped);
andrewbonney	0:ec559500a63f	496	concat_chksummed += seglen;
andrewbonney	0:ec559500a63f	497	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	498	/* reference the non-volatile payload data */
andrewbonney	0:ec559500a63f	499	concat_p->payload = (u8_t*)arg + pos;
andrewbonney	0:ec559500a63f	500	}
andrewbonney	0:ec559500a63f	501
andrewbonney	0:ec559500a63f	502	pos += seglen;
andrewbonney	0:ec559500a63f	503	queuelen += pbuf_clen(concat_p);
andrewbonney	0:ec559500a63f	504	}
andrewbonney	0:ec559500a63f	505	} else {
andrewbonney	0:ec559500a63f	506	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	507	LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
andrewbonney	0:ec559500a63f	508	pcb->unsent_oversize == 0);
andrewbonney	0:ec559500a63f	509	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	510	}
andrewbonney	0:ec559500a63f	511
andrewbonney	0:ec559500a63f	512	/*
andrewbonney	0:ec559500a63f	513	* Phase 3: Create new segments.
andrewbonney	0:ec559500a63f	514	*
andrewbonney	0:ec559500a63f	515	* The new segments are chained together in the local 'queue'
andrewbonney	0:ec559500a63f	516	* variable, ready to be appended to pcb->unsent.
andrewbonney	0:ec559500a63f	517	*/
andrewbonney	0:ec559500a63f	518	while (pos < len) {
andrewbonney	0:ec559500a63f	519	struct pbuf *p;
andrewbonney	0:ec559500a63f	520	u16_t left = len - pos;
andrewbonney	0:ec559500a63f	521	u16_t max_len = pcb->mss - optlen;
andrewbonney	0:ec559500a63f	522	u16_t seglen = left > max_len ? max_len : left;
andrewbonney	0:ec559500a63f	523	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	524	u16_t chksum = 0;
andrewbonney	0:ec559500a63f	525	u8_t chksum_swapped = 0;
andrewbonney	0:ec559500a63f	526	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	527
andrewbonney	0:ec559500a63f	528	if (apiflags & TCP_WRITE_FLAG_COPY) {
andrewbonney	0:ec559500a63f	529	/* If copy is set, memory should be allocated and data copied
andrewbonney	0:ec559500a63f	530	* into pbuf */
andrewbonney	0:ec559500a63f	531	if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, pcb->mss, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
andrewbonney	0:ec559500a63f	532	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
andrewbonney	0:ec559500a63f	533	goto memerr;
andrewbonney	0:ec559500a63f	534	}
andrewbonney	0:ec559500a63f	535	LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
andrewbonney	0:ec559500a63f	536	(p->len >= seglen));
andrewbonney	0:ec559500a63f	537	TCP_DATA_COPY2((char )p->payload + optlen, (u8_t)arg + pos, seglen, &chksum, &chksum_swapped);
andrewbonney	0:ec559500a63f	538	} else {
andrewbonney	0:ec559500a63f	539	/* Copy is not set: First allocate a pbuf for holding the data.
andrewbonney	0:ec559500a63f	540	* Since the referenced data is available at least until it is
andrewbonney	0:ec559500a63f	541	* sent out on the link (as it has to be ACKed by the remote
andrewbonney	0:ec559500a63f	542	* party) we can safely use PBUF_ROM instead of PBUF_REF here.
andrewbonney	0:ec559500a63f	543	*/
andrewbonney	0:ec559500a63f	544	struct pbuf *p2;
andrewbonney	0:ec559500a63f	545	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	546	LWIP_ASSERT("oversize == 0", oversize == 0);
andrewbonney	0:ec559500a63f	547	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	548	if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
andrewbonney	0:ec559500a63f	549	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
andrewbonney	0:ec559500a63f	550	goto memerr;
andrewbonney	0:ec559500a63f	551	}
andrewbonney	0:ec559500a63f	552	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	553	/* calculate the checksum of nocopy-data */
andrewbonney	0:ec559500a63f	554	chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
andrewbonney	0:ec559500a63f	555	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	556	/* reference the non-volatile payload data */
andrewbonney	0:ec559500a63f	557	p2->payload = (u8_t*)arg + pos;
andrewbonney	0:ec559500a63f	558
andrewbonney	0:ec559500a63f	559	/* Second, allocate a pbuf for the headers. */
andrewbonney	0:ec559500a63f	560	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
andrewbonney	0:ec559500a63f	561	/* If allocation fails, we have to deallocate the data pbuf as
andrewbonney	0:ec559500a63f	562	* well. */
andrewbonney	0:ec559500a63f	563	pbuf_free(p2);
andrewbonney	0:ec559500a63f	564	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: could not allocate memory for header pbuf\n"));
andrewbonney	0:ec559500a63f	565	goto memerr;
andrewbonney	0:ec559500a63f	566	}
andrewbonney	0:ec559500a63f	567	/* Concatenate the headers and data pbufs together. */
andrewbonney	0:ec559500a63f	568	pbuf_cat(p/header/, p2/data/);
andrewbonney	0:ec559500a63f	569	}
andrewbonney	0:ec559500a63f	570
andrewbonney	0:ec559500a63f	571	queuelen += pbuf_clen(p);
andrewbonney	0:ec559500a63f	572
andrewbonney	0:ec559500a63f	573	/* Now that there are more segments queued, we check again if the
andrewbonney	0:ec559500a63f	574	* length of the queue exceeds the configured maximum or
andrewbonney	0:ec559500a63f	575	* overflows. */
andrewbonney	0:ec559500a63f	576	if ((queuelen > TCP_SND_QUEUELEN) \|\| (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
andrewbonney	0:ec559500a63f	577	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
andrewbonney	0:ec559500a63f	578	pbuf_free(p);
andrewbonney	0:ec559500a63f	579	goto memerr;
andrewbonney	0:ec559500a63f	580	}
andrewbonney	0:ec559500a63f	581
andrewbonney	0:ec559500a63f	582	if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
andrewbonney	0:ec559500a63f	583	goto memerr;
andrewbonney	0:ec559500a63f	584	}
andrewbonney	0:ec559500a63f	585	#if TCP_OVERSIZE_DBGCHECK
andrewbonney	0:ec559500a63f	586	seg->oversize_left = oversize;
andrewbonney	0:ec559500a63f	587	#endif /* TCP_OVERSIZE_DBGCHECK */
andrewbonney	0:ec559500a63f	588	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	589	seg->chksum = chksum;
andrewbonney	0:ec559500a63f	590	seg->chksum_swapped = chksum_swapped;
andrewbonney	0:ec559500a63f	591	seg->flags \|= TF_SEG_DATA_CHECKSUMMED;
andrewbonney	0:ec559500a63f	592	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	593	/* Fix dataptr for the nocopy case */
andrewbonney	0:ec559500a63f	594	if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
andrewbonney	0:ec559500a63f	595	seg->dataptr = (u8_t*)arg + pos;
andrewbonney	0:ec559500a63f	596	}
andrewbonney	0:ec559500a63f	597
andrewbonney	0:ec559500a63f	598	/* first segment of to-be-queued data? */
andrewbonney	0:ec559500a63f	599	if (queue == NULL) {
andrewbonney	0:ec559500a63f	600	queue = seg;
andrewbonney	0:ec559500a63f	601	} else {
andrewbonney	0:ec559500a63f	602	/* Attach the segment to the end of the queued segments */
andrewbonney	0:ec559500a63f	603	LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
andrewbonney	0:ec559500a63f	604	prev_seg->next = seg;
andrewbonney	0:ec559500a63f	605	}
andrewbonney	0:ec559500a63f	606	/* remember last segment of to-be-queued data for next iteration */
andrewbonney	0:ec559500a63f	607	prev_seg = seg;
andrewbonney	0:ec559500a63f	608
andrewbonney	0:ec559500a63f	609	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
andrewbonney	0:ec559500a63f	610	ntohl(seg->tcphdr->seqno),
andrewbonney	0:ec559500a63f	611	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
andrewbonney	0:ec559500a63f	612
andrewbonney	0:ec559500a63f	613	pos += seglen;
andrewbonney	0:ec559500a63f	614	}
andrewbonney	0:ec559500a63f	615
andrewbonney	0:ec559500a63f	616	/*
andrewbonney	0:ec559500a63f	617	* All three segmentation phases were successful. We can commit the
andrewbonney	0:ec559500a63f	618	* transaction.
andrewbonney	0:ec559500a63f	619	*/
andrewbonney	0:ec559500a63f	620
andrewbonney	0:ec559500a63f	621	/*
andrewbonney	0:ec559500a63f	622	* Phase 1: If data has been added to the preallocated tail of
andrewbonney	0:ec559500a63f	623	* last_unsent, we update the length fields of the pbuf chain.
andrewbonney	0:ec559500a63f	624	*/
andrewbonney	0:ec559500a63f	625	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	626	if (oversize_used > 0) {
andrewbonney	0:ec559500a63f	627	struct pbuf *p;
andrewbonney	0:ec559500a63f	628	/* Bump tot_len of whole chain, len of tail */
andrewbonney	0:ec559500a63f	629	for (p = last_unsent->p; p; p = p->next) {
andrewbonney	0:ec559500a63f	630	p->tot_len += oversize_used;
andrewbonney	0:ec559500a63f	631	if (p->next == NULL) {
andrewbonney	0:ec559500a63f	632	TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
andrewbonney	0:ec559500a63f	633	p->len += oversize_used;
andrewbonney	0:ec559500a63f	634	}
andrewbonney	0:ec559500a63f	635	}
andrewbonney	0:ec559500a63f	636	last_unsent->len += oversize_used;
andrewbonney	0:ec559500a63f	637	#if TCP_OVERSIZE_DBGCHECK
andrewbonney	0:ec559500a63f	638	last_unsent->oversize_left -= oversize_used;
andrewbonney	0:ec559500a63f	639	#endif /* TCP_OVERSIZE_DBGCHECK */
andrewbonney	0:ec559500a63f	640	}
andrewbonney	0:ec559500a63f	641	pcb->unsent_oversize = oversize;
andrewbonney	0:ec559500a63f	642	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	643
andrewbonney	0:ec559500a63f	644	/*
andrewbonney	0:ec559500a63f	645	* Phase 2: concat_p can be concatenated onto last_unsent->p
andrewbonney	0:ec559500a63f	646	*/
andrewbonney	0:ec559500a63f	647	if (concat_p != NULL) {
andrewbonney	0:ec559500a63f	648	LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
andrewbonney	0:ec559500a63f	649	(last_unsent != NULL));
andrewbonney	0:ec559500a63f	650	pbuf_cat(last_unsent->p, concat_p);
andrewbonney	0:ec559500a63f	651	last_unsent->len += concat_p->tot_len;
andrewbonney	0:ec559500a63f	652	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	653	if (concat_chksummed) {
andrewbonney	0:ec559500a63f	654	tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
andrewbonney	0:ec559500a63f	655	&last_unsent->chksum_swapped);
andrewbonney	0:ec559500a63f	656	last_unsent->flags \|= TF_SEG_DATA_CHECKSUMMED;
andrewbonney	0:ec559500a63f	657	}
andrewbonney	0:ec559500a63f	658	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	659	}
andrewbonney	0:ec559500a63f	660
andrewbonney	0:ec559500a63f	661	/*
andrewbonney	0:ec559500a63f	662	* Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
andrewbonney	0:ec559500a63f	663	* is harmless
andrewbonney	0:ec559500a63f	664	*/
andrewbonney	0:ec559500a63f	665	if (last_unsent == NULL) {
andrewbonney	0:ec559500a63f	666	pcb->unsent = queue;
andrewbonney	0:ec559500a63f	667	} else {
andrewbonney	0:ec559500a63f	668	last_unsent->next = queue;
andrewbonney	0:ec559500a63f	669	}
andrewbonney	0:ec559500a63f	670
andrewbonney	0:ec559500a63f	671	/*
andrewbonney	0:ec559500a63f	672	* Finally update the pcb state.
andrewbonney	0:ec559500a63f	673	*/
andrewbonney	0:ec559500a63f	674	pcb->snd_lbb += len;
andrewbonney	0:ec559500a63f	675	pcb->snd_buf -= len;
andrewbonney	0:ec559500a63f	676	pcb->snd_queuelen = queuelen;
andrewbonney	0:ec559500a63f	677
andrewbonney	0:ec559500a63f	678	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
andrewbonney	0:ec559500a63f	679	pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	680	if (pcb->snd_queuelen != 0) {
andrewbonney	0:ec559500a63f	681	LWIP_ASSERT("tcp_write: valid queue length",
andrewbonney	0:ec559500a63f	682	pcb->unacked != NULL \|\| pcb->unsent != NULL);
andrewbonney	0:ec559500a63f	683	}
andrewbonney	0:ec559500a63f	684
andrewbonney	0:ec559500a63f	685	/* Set the PSH flag in the last segment that we enqueued. */
andrewbonney	0:ec559500a63f	686	if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
andrewbonney	0:ec559500a63f	687	TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
andrewbonney	0:ec559500a63f	688	}
andrewbonney	0:ec559500a63f	689
andrewbonney	0:ec559500a63f	690	return ERR_OK;
andrewbonney	0:ec559500a63f	691	memerr:
andrewbonney	0:ec559500a63f	692	pcb->flags \|= TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	693	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	694
andrewbonney	0:ec559500a63f	695	if (concat_p != NULL) {
andrewbonney	0:ec559500a63f	696	pbuf_free(concat_p);
andrewbonney	0:ec559500a63f	697	}
andrewbonney	0:ec559500a63f	698	if (queue != NULL) {
andrewbonney	0:ec559500a63f	699	tcp_segs_free(queue);
andrewbonney	0:ec559500a63f	700	}
andrewbonney	0:ec559500a63f	701	if (pcb->snd_queuelen != 0) {
andrewbonney	0:ec559500a63f	702	LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL \|\|
andrewbonney	0:ec559500a63f	703	pcb->unsent != NULL);
andrewbonney	0:ec559500a63f	704	}
andrewbonney	0:ec559500a63f	705	LWIP_DEBUGF(TCP_QLEN_DEBUG \| LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	706	return ERR_MEM;
andrewbonney	0:ec559500a63f	707	}
andrewbonney	0:ec559500a63f	708
andrewbonney	0:ec559500a63f	709	/**
andrewbonney	0:ec559500a63f	710	* Enqueue TCP options for transmission.
andrewbonney	0:ec559500a63f	711	*
andrewbonney	0:ec559500a63f	712	* Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
andrewbonney	0:ec559500a63f	713	*
andrewbonney	0:ec559500a63f	714	* @param pcb Protocol control block for the TCP connection.
andrewbonney	0:ec559500a63f	715	* @param flags TCP header flags to set in the outgoing segment.
andrewbonney	0:ec559500a63f	716	* @param optdata pointer to TCP options, or NULL.
andrewbonney	0:ec559500a63f	717	* @param optlen length of TCP options in bytes.
andrewbonney	0:ec559500a63f	718	*/
andrewbonney	0:ec559500a63f	719	err_t
andrewbonney	0:ec559500a63f	720	tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
andrewbonney	0:ec559500a63f	721	{
andrewbonney	0:ec559500a63f	722	struct pbuf *p;
andrewbonney	0:ec559500a63f	723	struct tcp_seg *seg;
andrewbonney	0:ec559500a63f	724	u8_t optflags = 0;
andrewbonney	0:ec559500a63f	725	u8_t optlen = 0;
andrewbonney	0:ec559500a63f	726
andrewbonney	0:ec559500a63f	727	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	728
andrewbonney	0:ec559500a63f	729	LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
andrewbonney	0:ec559500a63f	730	(flags & (TCP_SYN \| TCP_FIN)) != 0);
andrewbonney	0:ec559500a63f	731
andrewbonney	0:ec559500a63f	732	/* check for configured max queuelen and possible overflow */
andrewbonney	0:ec559500a63f	733	if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) \|\| (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
andrewbonney	0:ec559500a63f	734	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
andrewbonney	0:ec559500a63f	735	pcb->snd_queuelen, TCP_SND_QUEUELEN));
andrewbonney	0:ec559500a63f	736	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	737	pcb->flags \|= TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	738	return ERR_MEM;
andrewbonney	0:ec559500a63f	739	}
andrewbonney	0:ec559500a63f	740
andrewbonney	0:ec559500a63f	741	if (flags & TCP_SYN) {
andrewbonney	0:ec559500a63f	742	optflags = TF_SEG_OPTS_MSS;
andrewbonney	0:ec559500a63f	743	}
andrewbonney	0:ec559500a63f	744	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	745	if ((pcb->flags & TF_TIMESTAMP)) {
andrewbonney	0:ec559500a63f	746	optflags \|= TF_SEG_OPTS_TS;
andrewbonney	0:ec559500a63f	747	}
andrewbonney	0:ec559500a63f	748	#endif /* LWIP_TCP_TIMESTAMPS */
andrewbonney	0:ec559500a63f	749	optlen = LWIP_TCP_OPT_LENGTH(optflags);
andrewbonney	0:ec559500a63f	750
andrewbonney	0:ec559500a63f	751	/* tcp_enqueue_flags is always called with either SYN or FIN in flags.
andrewbonney	0:ec559500a63f	752	* We need one available snd_buf byte to do that.
andrewbonney	0:ec559500a63f	753	* This means we can't send FIN while snd_buf==0. A better fix would be to
andrewbonney	0:ec559500a63f	754	* not include SYN and FIN sequence numbers in the snd_buf count. */
andrewbonney	0:ec559500a63f	755	if (pcb->snd_buf == 0) {
andrewbonney	0:ec559500a63f	756	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| 3, ("tcp_enqueue_flags: no send buffer available\n"));
andrewbonney	0:ec559500a63f	757	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	758	return ERR_MEM;
andrewbonney	0:ec559500a63f	759	}
andrewbonney	0:ec559500a63f	760
andrewbonney	0:ec559500a63f	761	/* Allocate pbuf with room for TCP header + options */
andrewbonney	0:ec559500a63f	762	if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
andrewbonney	0:ec559500a63f	763	pcb->flags \|= TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	764	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	765	return ERR_MEM;
andrewbonney	0:ec559500a63f	766	}
andrewbonney	0:ec559500a63f	767	LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
andrewbonney	0:ec559500a63f	768	(p->len >= optlen));
andrewbonney	0:ec559500a63f	769
andrewbonney	0:ec559500a63f	770	/* Allocate memory for tcp_seg, and fill in fields. */
andrewbonney	0:ec559500a63f	771	if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
andrewbonney	0:ec559500a63f	772	pcb->flags \|= TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	773	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	774	return ERR_MEM;
andrewbonney	0:ec559500a63f	775	}
andrewbonney	0:ec559500a63f	776	LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
andrewbonney	0:ec559500a63f	777
andrewbonney	0:ec559500a63f	778	LWIP_DEBUGF(TCP_OUTPUT_DEBUG \| LWIP_DBG_TRACE,
andrewbonney	0:ec559500a63f	779	("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
andrewbonney	0:ec559500a63f	780	ntohl(seg->tcphdr->seqno),
andrewbonney	0:ec559500a63f	781	ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
andrewbonney	0:ec559500a63f	782	(u16_t)flags));
andrewbonney	0:ec559500a63f	783
andrewbonney	0:ec559500a63f	784	/* Now append seg to pcb->unsent queue */
andrewbonney	0:ec559500a63f	785	if (pcb->unsent == NULL) {
andrewbonney	0:ec559500a63f	786	pcb->unsent = seg;
andrewbonney	0:ec559500a63f	787	} else {
andrewbonney	0:ec559500a63f	788	struct tcp_seg *useg;
andrewbonney	0:ec559500a63f	789	for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
andrewbonney	0:ec559500a63f	790	useg->next = seg;
andrewbonney	0:ec559500a63f	791	}
andrewbonney	0:ec559500a63f	792	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	793	/* The new unsent tail has no space */
andrewbonney	0:ec559500a63f	794	pcb->unsent_oversize = 0;
andrewbonney	0:ec559500a63f	795	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	796
andrewbonney	0:ec559500a63f	797	/* SYN and FIN bump the sequence number */
andrewbonney	0:ec559500a63f	798	if ((flags & TCP_SYN) \|\| (flags & TCP_FIN)) {
andrewbonney	0:ec559500a63f	799	pcb->snd_lbb++;
andrewbonney	0:ec559500a63f	800	/* optlen does not influence snd_buf */
andrewbonney	0:ec559500a63f	801	pcb->snd_buf--;
andrewbonney	0:ec559500a63f	802	}
andrewbonney	0:ec559500a63f	803	if (flags & TCP_FIN) {
andrewbonney	0:ec559500a63f	804	pcb->flags \|= TF_FIN;
andrewbonney	0:ec559500a63f	805	}
andrewbonney	0:ec559500a63f	806
andrewbonney	0:ec559500a63f	807	/* update number of segments on the queues */
andrewbonney	0:ec559500a63f	808	pcb->snd_queuelen += pbuf_clen(seg->p);
andrewbonney	0:ec559500a63f	809	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	810	if (pcb->snd_queuelen != 0) {
andrewbonney	0:ec559500a63f	811	LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
andrewbonney	0:ec559500a63f	812	pcb->unacked != NULL \|\| pcb->unsent != NULL);
andrewbonney	0:ec559500a63f	813	}
andrewbonney	0:ec559500a63f	814
andrewbonney	0:ec559500a63f	815	return ERR_OK;
andrewbonney	0:ec559500a63f	816	}
andrewbonney	0:ec559500a63f	817
andrewbonney	0:ec559500a63f	818
andrewbonney	0:ec559500a63f	819	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	820	/* Build a timestamp option (12 bytes long) at the specified options pointer)
andrewbonney	0:ec559500a63f	821	*
andrewbonney	0:ec559500a63f	822	* @param pcb tcp_pcb
andrewbonney	0:ec559500a63f	823	* @param opts option pointer where to store the timestamp option
andrewbonney	0:ec559500a63f	824	*/
andrewbonney	0:ec559500a63f	825	static void
andrewbonney	0:ec559500a63f	826	tcp_build_timestamp_option(struct tcp_pcb pcb, u32_t opts)
andrewbonney	0:ec559500a63f	827	{
andrewbonney	0:ec559500a63f	828	/* Pad with two NOP options to make everything nicely aligned */
andrewbonney	0:ec559500a63f	829	opts[0] = PP_HTONL(0x0101080A);
andrewbonney	0:ec559500a63f	830	opts[1] = htonl(sys_now());
andrewbonney	0:ec559500a63f	831	opts[2] = htonl(pcb->ts_recent);
andrewbonney	0:ec559500a63f	832	}
andrewbonney	0:ec559500a63f	833	#endif
andrewbonney	0:ec559500a63f	834
andrewbonney	0:ec559500a63f	835	/** Send an ACK without data.
andrewbonney	0:ec559500a63f	836	*
andrewbonney	0:ec559500a63f	837	* @param pcb Protocol control block for the TCP connection to send the ACK
andrewbonney	0:ec559500a63f	838	*/
andrewbonney	0:ec559500a63f	839	err_t
andrewbonney	0:ec559500a63f	840	tcp_send_empty_ack(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	841	{
andrewbonney	0:ec559500a63f	842	struct pbuf *p;
andrewbonney	0:ec559500a63f	843	struct tcp_hdr *tcphdr;
andrewbonney	0:ec559500a63f	844	u8_t optlen = 0;
andrewbonney	0:ec559500a63f	845
andrewbonney	0:ec559500a63f	846	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	847	if (pcb->flags & TF_TIMESTAMP) {
andrewbonney	0:ec559500a63f	848	optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
andrewbonney	0:ec559500a63f	849	}
andrewbonney	0:ec559500a63f	850	#endif
andrewbonney	0:ec559500a63f	851
andrewbonney	0:ec559500a63f	852	p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
andrewbonney	0:ec559500a63f	853	if (p == NULL) {
andrewbonney	0:ec559500a63f	854	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
andrewbonney	0:ec559500a63f	855	return ERR_BUF;
andrewbonney	0:ec559500a63f	856	}
andrewbonney	0:ec559500a63f	857	tcphdr = (struct tcp_hdr *)p->payload;
andrewbonney	0:ec559500a63f	858	LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
andrewbonney	0:ec559500a63f	859	("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
andrewbonney	0:ec559500a63f	860	/* remove ACK flags from the PCB, as we send an empty ACK now */
andrewbonney	0:ec559500a63f	861	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
andrewbonney	0:ec559500a63f	862
andrewbonney	0:ec559500a63f	863	/* NB. MSS option is only sent on SYNs, so ignore it here */
andrewbonney	0:ec559500a63f	864	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	865	pcb->ts_lastacksent = pcb->rcv_nxt;
andrewbonney	0:ec559500a63f	866
andrewbonney	0:ec559500a63f	867	if (pcb->flags & TF_TIMESTAMP) {
andrewbonney	0:ec559500a63f	868	tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
andrewbonney	0:ec559500a63f	869	}
andrewbonney	0:ec559500a63f	870	#endif
andrewbonney	0:ec559500a63f	871
andrewbonney	0:ec559500a63f	872	#if CHECKSUM_GEN_TCP
andrewbonney	0:ec559500a63f	873	tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
andrewbonney	0:ec559500a63f	874	IP_PROTO_TCP, p->tot_len);
andrewbonney	0:ec559500a63f	875	#endif
andrewbonney	0:ec559500a63f	876	#if LWIP_NETIF_HWADDRHINT
andrewbonney	0:ec559500a63f	877	ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
andrewbonney	0:ec559500a63f	878	IP_PROTO_TCP, &(pcb->addr_hint));
andrewbonney	0:ec559500a63f	879	#else /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	880	ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
andrewbonney	0:ec559500a63f	881	IP_PROTO_TCP);
andrewbonney	0:ec559500a63f	882	#endif /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	883	pbuf_free(p);
andrewbonney	0:ec559500a63f	884
andrewbonney	0:ec559500a63f	885	return ERR_OK;
andrewbonney	0:ec559500a63f	886	}
andrewbonney	0:ec559500a63f	887
andrewbonney	0:ec559500a63f	888	/**
andrewbonney	0:ec559500a63f	889	* Find out what we can send and send it
andrewbonney	0:ec559500a63f	890	*
andrewbonney	0:ec559500a63f	891	* @param pcb Protocol control block for the TCP connection to send data
andrewbonney	0:ec559500a63f	892	* @return ERR_OK if data has been sent or nothing to send
andrewbonney	0:ec559500a63f	893	* another err_t on error
andrewbonney	0:ec559500a63f	894	*/
andrewbonney	0:ec559500a63f	895	err_t
andrewbonney	0:ec559500a63f	896	tcp_output(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	897	{
andrewbonney	0:ec559500a63f	898	struct tcp_seg seg, useg;
andrewbonney	0:ec559500a63f	899	u32_t wnd, snd_nxt;
andrewbonney	0:ec559500a63f	900	#if TCP_CWND_DEBUG
andrewbonney	0:ec559500a63f	901	s16_t i = 0;
andrewbonney	0:ec559500a63f	902	#endif /* TCP_CWND_DEBUG */
andrewbonney	0:ec559500a63f	903
andrewbonney	0:ec559500a63f	904	/* First, check if we are invoked by the TCP input processing
andrewbonney	0:ec559500a63f	905	code. If so, we do not output anything. Instead, we rely on the
andrewbonney	0:ec559500a63f	906	input processing code to call us when input processing is done
andrewbonney	0:ec559500a63f	907	with. */
andrewbonney	0:ec559500a63f	908	if (tcp_input_pcb == pcb) {
andrewbonney	0:ec559500a63f	909	return ERR_OK;
andrewbonney	0:ec559500a63f	910	}
andrewbonney	0:ec559500a63f	911
andrewbonney	0:ec559500a63f	912	wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
andrewbonney	0:ec559500a63f	913
andrewbonney	0:ec559500a63f	914	seg = pcb->unsent;
andrewbonney	0:ec559500a63f	915
andrewbonney	0:ec559500a63f	916	/* If the TF_ACK_NOW flag is set and no data will be sent (either
andrewbonney	0:ec559500a63f	917	* because the ->unsent queue is empty or because the window does
andrewbonney	0:ec559500a63f	918	* not allow it), construct an empty ACK segment and send it.
andrewbonney	0:ec559500a63f	919	*
andrewbonney	0:ec559500a63f	920	* If data is to be sent, we will just piggyback the ACK (see below).
andrewbonney	0:ec559500a63f	921	*/
andrewbonney	0:ec559500a63f	922	if (pcb->flags & TF_ACK_NOW &&
andrewbonney	0:ec559500a63f	923	(seg == NULL \|\|
andrewbonney	0:ec559500a63f	924	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
andrewbonney	0:ec559500a63f	925	return tcp_send_empty_ack(pcb);
andrewbonney	0:ec559500a63f	926	}
andrewbonney	0:ec559500a63f	927
andrewbonney	0:ec559500a63f	928	/* useg should point to last segment on unacked queue */
andrewbonney	0:ec559500a63f	929	useg = pcb->unacked;
andrewbonney	0:ec559500a63f	930	if (useg != NULL) {
andrewbonney	0:ec559500a63f	931	for (; useg->next != NULL; useg = useg->next);
andrewbonney	0:ec559500a63f	932	}
andrewbonney	0:ec559500a63f	933
andrewbonney	0:ec559500a63f	934	#if TCP_OUTPUT_DEBUG
andrewbonney	0:ec559500a63f	935	if (seg == NULL) {
andrewbonney	0:ec559500a63f	936	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
andrewbonney	0:ec559500a63f	937	(void*)pcb->unsent));
andrewbonney	0:ec559500a63f	938	}
andrewbonney	0:ec559500a63f	939	#endif /* TCP_OUTPUT_DEBUG */
andrewbonney	0:ec559500a63f	940	#if TCP_CWND_DEBUG
andrewbonney	0:ec559500a63f	941	if (seg == NULL) {
andrewbonney	0:ec559500a63f	942	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
andrewbonney	0:ec559500a63f	943	", cwnd %"U16_F", wnd %"U32_F
andrewbonney	0:ec559500a63f	944	", seg == NULL, ack %"U32_F"\n",
andrewbonney	0:ec559500a63f	945	pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
andrewbonney	0:ec559500a63f	946	} else {
andrewbonney	0:ec559500a63f	947	LWIP_DEBUGF(TCP_CWND_DEBUG,
andrewbonney	0:ec559500a63f	948	("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
andrewbonney	0:ec559500a63f	949	", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
andrewbonney	0:ec559500a63f	950	pcb->snd_wnd, pcb->cwnd, wnd,
andrewbonney	0:ec559500a63f	951	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
andrewbonney	0:ec559500a63f	952	ntohl(seg->tcphdr->seqno), pcb->lastack));
andrewbonney	0:ec559500a63f	953	}
andrewbonney	0:ec559500a63f	954	#endif /* TCP_CWND_DEBUG */
andrewbonney	0:ec559500a63f	955	/* data available and window allows it to be sent? */
andrewbonney	0:ec559500a63f	956	while (seg != NULL &&
andrewbonney	0:ec559500a63f	957	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
andrewbonney	0:ec559500a63f	958	LWIP_ASSERT("RST not expected here!",
andrewbonney	0:ec559500a63f	959	(TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
andrewbonney	0:ec559500a63f	960	/* Stop sending if the nagle algorithm would prevent it
andrewbonney	0:ec559500a63f	961	* Don't stop:
andrewbonney	0:ec559500a63f	962	* - if tcp_write had a memory error before (prevent delayed ACK timeout) or
andrewbonney	0:ec559500a63f	963	* - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
andrewbonney	0:ec559500a63f	964	* either seg->next != NULL or pcb->unacked == NULL;
andrewbonney	0:ec559500a63f	965	* RST is no sent using tcp_write/tcp_output.
andrewbonney	0:ec559500a63f	966	*/
andrewbonney	0:ec559500a63f	967	if((tcp_do_output_nagle(pcb) == 0) &&
andrewbonney	0:ec559500a63f	968	((pcb->flags & (TF_NAGLEMEMERR \| TF_FIN)) == 0)){
andrewbonney	0:ec559500a63f	969	break;
andrewbonney	0:ec559500a63f	970	}
andrewbonney	0:ec559500a63f	971	#if TCP_CWND_DEBUG
andrewbonney	0:ec559500a63f	972	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n",
andrewbonney	0:ec559500a63f	973	pcb->snd_wnd, pcb->cwnd, wnd,
andrewbonney	0:ec559500a63f	974	ntohl(seg->tcphdr->seqno) + seg->len -
andrewbonney	0:ec559500a63f	975	pcb->lastack,
andrewbonney	0:ec559500a63f	976	ntohl(seg->tcphdr->seqno), pcb->lastack, i));
andrewbonney	0:ec559500a63f	977	++i;
andrewbonney	0:ec559500a63f	978	#endif /* TCP_CWND_DEBUG */
andrewbonney	0:ec559500a63f	979
andrewbonney	0:ec559500a63f	980	pcb->unsent = seg->next;
andrewbonney	0:ec559500a63f	981
andrewbonney	0:ec559500a63f	982	if (pcb->state != SYN_SENT) {
andrewbonney	0:ec559500a63f	983	TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
andrewbonney	0:ec559500a63f	984	pcb->flags &= ~(TF_ACK_DELAY \| TF_ACK_NOW);
andrewbonney	0:ec559500a63f	985	}
andrewbonney	0:ec559500a63f	986
andrewbonney	0:ec559500a63f	987	tcp_output_segment(seg, pcb);
andrewbonney	0:ec559500a63f	988
andrewbonney	0:ec559500a63f	989	snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
andrewbonney	0:ec559500a63f	990
andrewbonney	0:ec559500a63f	991	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: pcb->snd_nxt was %"U32_F" seqno=%"U32_F" len=%"U32_F" new snd_nxt=%"U32_F"\n", //DG
andrewbonney	0:ec559500a63f	992	pcb->snd_nxt, ntohl(seg->tcphdr->seqno), TCP_TCPLEN(seg), snd_nxt));
andrewbonney	0:ec559500a63f	993
andrewbonney	0:ec559500a63f	994	if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
andrewbonney	0:ec559500a63f	995	pcb->snd_nxt = snd_nxt;
andrewbonney	0:ec559500a63f	996	}
andrewbonney	0:ec559500a63f	997	/* put segment on unacknowledged list if length > 0 */
andrewbonney	0:ec559500a63f	998	if (TCP_TCPLEN(seg) > 0) {
andrewbonney	0:ec559500a63f	999	seg->next = NULL;
andrewbonney	0:ec559500a63f	1000	/* unacked list is empty? */
andrewbonney	0:ec559500a63f	1001	if (pcb->unacked == NULL) {
andrewbonney	0:ec559500a63f	1002	pcb->unacked = seg;
andrewbonney	0:ec559500a63f	1003	useg = seg;
andrewbonney	0:ec559500a63f	1004	/* unacked list is not empty? */
andrewbonney	0:ec559500a63f	1005	} else {
andrewbonney	0:ec559500a63f	1006	/* In the case of fast retransmit, the packet should not go to the tail
andrewbonney	0:ec559500a63f	1007	* of the unacked queue, but rather somewhere before it. We need to check for
andrewbonney	0:ec559500a63f	1008	* this case. -STJ Jul 27, 2004 */
andrewbonney	0:ec559500a63f	1009	if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
andrewbonney	0:ec559500a63f	1010	/* add segment to before tail of unacked list, keeping the list sorted */
andrewbonney	0:ec559500a63f	1011	struct tcp_seg **cur_seg = &(pcb->unacked);
andrewbonney	0:ec559500a63f	1012	while (*cur_seg &&
andrewbonney	0:ec559500a63f	1013	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
andrewbonney	0:ec559500a63f	1014	cur_seg = &((*cur_seg)->next );
andrewbonney	0:ec559500a63f	1015	}
andrewbonney	0:ec559500a63f	1016	seg->next = (*cur_seg);
andrewbonney	0:ec559500a63f	1017	(*cur_seg) = seg;
andrewbonney	0:ec559500a63f	1018	} else {
andrewbonney	0:ec559500a63f	1019	/* add segment to tail of unacked list */
andrewbonney	0:ec559500a63f	1020	useg->next = seg;
andrewbonney	0:ec559500a63f	1021	useg = useg->next;
andrewbonney	0:ec559500a63f	1022	}
andrewbonney	0:ec559500a63f	1023	}
andrewbonney	0:ec559500a63f	1024	/* do not queue empty segments on the unacked list */
andrewbonney	0:ec559500a63f	1025	} else {
andrewbonney	0:ec559500a63f	1026	tcp_seg_free(seg);
andrewbonney	0:ec559500a63f	1027	}
andrewbonney	0:ec559500a63f	1028	seg = pcb->unsent;
andrewbonney	0:ec559500a63f	1029	}
andrewbonney	0:ec559500a63f	1030	#if TCP_OVERSIZE
andrewbonney	0:ec559500a63f	1031	if (pcb->unsent == NULL) {
andrewbonney	0:ec559500a63f	1032	/* last unsent has been removed, reset unsent_oversize */
andrewbonney	0:ec559500a63f	1033	pcb->unsent_oversize = 0;
andrewbonney	0:ec559500a63f	1034	}
andrewbonney	0:ec559500a63f	1035	#endif /* TCP_OVERSIZE */
andrewbonney	0:ec559500a63f	1036
andrewbonney	0:ec559500a63f	1037	if (seg != NULL && pcb->persist_backoff == 0 &&
andrewbonney	0:ec559500a63f	1038	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) {
andrewbonney	0:ec559500a63f	1039	/* prepare for persist timer */
andrewbonney	0:ec559500a63f	1040	pcb->persist_cnt = 0;
andrewbonney	0:ec559500a63f	1041	pcb->persist_backoff = 1;
andrewbonney	0:ec559500a63f	1042	}
andrewbonney	0:ec559500a63f	1043
andrewbonney	0:ec559500a63f	1044	pcb->flags &= ~TF_NAGLEMEMERR;
andrewbonney	0:ec559500a63f	1045	return ERR_OK;
andrewbonney	0:ec559500a63f	1046	}
andrewbonney	0:ec559500a63f	1047
andrewbonney	0:ec559500a63f	1048	/**
andrewbonney	0:ec559500a63f	1049	* Called by tcp_output() to actually send a TCP segment over IP.
andrewbonney	0:ec559500a63f	1050	*
andrewbonney	0:ec559500a63f	1051	* @param seg the tcp_seg to send
andrewbonney	0:ec559500a63f	1052	* @param pcb the tcp_pcb for the TCP connection used to send the segment
andrewbonney	0:ec559500a63f	1053	*/
andrewbonney	0:ec559500a63f	1054	static void
andrewbonney	0:ec559500a63f	1055	tcp_output_segment(struct tcp_seg seg, struct tcp_pcb pcb)
andrewbonney	0:ec559500a63f	1056	{
andrewbonney	0:ec559500a63f	1057	u16_t len;
andrewbonney	0:ec559500a63f	1058	struct netif *netif;
andrewbonney	0:ec559500a63f	1059	u32_t *opts;
andrewbonney	0:ec559500a63f	1060
andrewbonney	0:ec559500a63f	1061	/** @bug Exclude retransmitted segments from this count. */
andrewbonney	0:ec559500a63f	1062	snmp_inc_tcpoutsegs();
andrewbonney	0:ec559500a63f	1063
andrewbonney	0:ec559500a63f	1064	/* The TCP header has already been constructed, but the ackno and
andrewbonney	0:ec559500a63f	1065	wnd fields remain. */
andrewbonney	0:ec559500a63f	1066	seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
andrewbonney	0:ec559500a63f	1067
andrewbonney	0:ec559500a63f	1068	/* advertise our receive window size in this TCP segment */
andrewbonney	0:ec559500a63f	1069	seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
andrewbonney	0:ec559500a63f	1070
andrewbonney	0:ec559500a63f	1071	pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
andrewbonney	0:ec559500a63f	1072
andrewbonney	0:ec559500a63f	1073	/* Add any requested options. NB MSS option is only set on SYN
andrewbonney	0:ec559500a63f	1074	packets, so ignore it here */
andrewbonney	0:ec559500a63f	1075	LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
andrewbonney	0:ec559500a63f	1076	opts = (u32_t )(void )(seg->tcphdr + 1);
andrewbonney	0:ec559500a63f	1077	if (seg->flags & TF_SEG_OPTS_MSS) {
andrewbonney	0:ec559500a63f	1078	TCP_BUILD_MSS_OPTION(*opts);
andrewbonney	0:ec559500a63f	1079	opts += 1;
andrewbonney	0:ec559500a63f	1080	}
andrewbonney	0:ec559500a63f	1081	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	1082	pcb->ts_lastacksent = pcb->rcv_nxt;
andrewbonney	0:ec559500a63f	1083
andrewbonney	0:ec559500a63f	1084	if (seg->flags & TF_SEG_OPTS_TS) {
andrewbonney	0:ec559500a63f	1085	tcp_build_timestamp_option(pcb, opts);
andrewbonney	0:ec559500a63f	1086	opts += 3;
andrewbonney	0:ec559500a63f	1087	}
andrewbonney	0:ec559500a63f	1088	#endif
andrewbonney	0:ec559500a63f	1089
andrewbonney	0:ec559500a63f	1090	/* If we don't have a local IP address, we get one by
andrewbonney	0:ec559500a63f	1091	calling ip_route(). */
andrewbonney	0:ec559500a63f	1092	if (ip_addr_isany(&(pcb->local_ip))) {
andrewbonney	0:ec559500a63f	1093	netif = ip_route(&(pcb->remote_ip));
andrewbonney	0:ec559500a63f	1094	if (netif == NULL) {
andrewbonney	0:ec559500a63f	1095	return;
andrewbonney	0:ec559500a63f	1096	}
andrewbonney	0:ec559500a63f	1097	ip_addr_copy(pcb->local_ip, netif->ip_addr);
andrewbonney	0:ec559500a63f	1098	}
andrewbonney	0:ec559500a63f	1099
andrewbonney	0:ec559500a63f	1100	/* Set retransmission timer running if it is not currently enabled */
andrewbonney	0:ec559500a63f	1101	if(pcb->rtime == -1) {
andrewbonney	0:ec559500a63f	1102	pcb->rtime = 0;
andrewbonney	0:ec559500a63f	1103	}
andrewbonney	0:ec559500a63f	1104
andrewbonney	0:ec559500a63f	1105	if (pcb->rttest == 0) {
andrewbonney	0:ec559500a63f	1106	pcb->rttest = tcp_ticks;
andrewbonney	0:ec559500a63f	1107	pcb->rtseq = ntohl(seg->tcphdr->seqno);
andrewbonney	0:ec559500a63f	1108
andrewbonney	0:ec559500a63f	1109	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
andrewbonney	0:ec559500a63f	1110	}
andrewbonney	0:ec559500a63f	1111	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
andrewbonney	0:ec559500a63f	1112	htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
andrewbonney	0:ec559500a63f	1113	seg->len));
andrewbonney	0:ec559500a63f	1114
andrewbonney	0:ec559500a63f	1115	len = (u16_t)((u8_t )seg->tcphdr - (u8_t )seg->p->payload);
andrewbonney	0:ec559500a63f	1116
andrewbonney	0:ec559500a63f	1117	seg->p->len -= len;
andrewbonney	0:ec559500a63f	1118	seg->p->tot_len -= len;
andrewbonney	0:ec559500a63f	1119
andrewbonney	0:ec559500a63f	1120	seg->p->payload = seg->tcphdr;
andrewbonney	0:ec559500a63f	1121
andrewbonney	0:ec559500a63f	1122	seg->tcphdr->chksum = 0;
andrewbonney	0:ec559500a63f	1123	#if CHECKSUM_GEN_TCP
andrewbonney	0:ec559500a63f	1124	#if TCP_CHECKSUM_ON_COPY
andrewbonney	0:ec559500a63f	1125	{
andrewbonney	0:ec559500a63f	1126	u32_t acc;
andrewbonney	0:ec559500a63f	1127	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
andrewbonney	0:ec559500a63f	1128	u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
andrewbonney	0:ec559500a63f	1129	&(pcb->remote_ip),
andrewbonney	0:ec559500a63f	1130	IP_PROTO_TCP, seg->p->tot_len);
andrewbonney	0:ec559500a63f	1131	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
andrewbonney	0:ec559500a63f	1132	if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
andrewbonney	0:ec559500a63f	1133	LWIP_ASSERT("data included but not checksummed",
andrewbonney	0:ec559500a63f	1134	seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
andrewbonney	0:ec559500a63f	1135	}
andrewbonney	0:ec559500a63f	1136
andrewbonney	0:ec559500a63f	1137	/* rebuild TCP header checksum (TCP header changes for retransmissions!) */
andrewbonney	0:ec559500a63f	1138	acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
andrewbonney	0:ec559500a63f	1139	&(pcb->remote_ip),
andrewbonney	0:ec559500a63f	1140	IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
andrewbonney	0:ec559500a63f	1141	/* add payload checksum */
andrewbonney	0:ec559500a63f	1142	if (seg->chksum_swapped) {
andrewbonney	0:ec559500a63f	1143	seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
andrewbonney	0:ec559500a63f	1144	seg->chksum_swapped = 0;
andrewbonney	0:ec559500a63f	1145	}
andrewbonney	0:ec559500a63f	1146	acc += (u16_t)~(seg->chksum);
andrewbonney	0:ec559500a63f	1147	seg->tcphdr->chksum = FOLD_U32T(acc);
andrewbonney	0:ec559500a63f	1148	#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
andrewbonney	0:ec559500a63f	1149	if (chksum_slow != seg->tcphdr->chksum) {
andrewbonney	0:ec559500a63f	1150	LWIP_DEBUGF(TCP_DEBUG \| LWIP_DBG_LEVEL_WARNING,
andrewbonney	0:ec559500a63f	1151	("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
andrewbonney	0:ec559500a63f	1152	seg->tcphdr->chksum, chksum_slow));
andrewbonney	0:ec559500a63f	1153	seg->tcphdr->chksum = chksum_slow;
andrewbonney	0:ec559500a63f	1154	}
andrewbonney	0:ec559500a63f	1155	#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
andrewbonney	0:ec559500a63f	1156	}
andrewbonney	0:ec559500a63f	1157	#else /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	1158	seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
andrewbonney	0:ec559500a63f	1159	&(pcb->remote_ip),
andrewbonney	0:ec559500a63f	1160	IP_PROTO_TCP, seg->p->tot_len);
andrewbonney	0:ec559500a63f	1161	#endif /* TCP_CHECKSUM_ON_COPY */
andrewbonney	0:ec559500a63f	1162	#endif /* CHECKSUM_GEN_TCP */
andrewbonney	0:ec559500a63f	1163	TCP_STATS_INC(tcp.xmit);
andrewbonney	0:ec559500a63f	1164
andrewbonney	0:ec559500a63f	1165	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: Before ip_out seqno = %"U32_F"\n",
andrewbonney	0:ec559500a63f	1166	htonl(seg->tcphdr->seqno))); //DG
andrewbonney	0:ec559500a63f	1167
andrewbonney	0:ec559500a63f	1168	#if LWIP_NETIF_HWADDRHINT
andrewbonney	0:ec559500a63f	1169	ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
andrewbonney	0:ec559500a63f	1170	IP_PROTO_TCP, &(pcb->addr_hint));
andrewbonney	0:ec559500a63f	1171	#else /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	1172	ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
andrewbonney	0:ec559500a63f	1173	IP_PROTO_TCP);
andrewbonney	0:ec559500a63f	1174	#endif /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	1175
andrewbonney	0:ec559500a63f	1176	LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: After ip_out seqno = %"U32_F"\n",
andrewbonney	0:ec559500a63f	1177	htonl(seg->tcphdr->seqno))); //DG
andrewbonney	0:ec559500a63f	1178
andrewbonney	0:ec559500a63f	1179
andrewbonney	0:ec559500a63f	1180	}
andrewbonney	0:ec559500a63f	1181
andrewbonney	0:ec559500a63f	1182	/**
andrewbonney	0:ec559500a63f	1183	* Send a TCP RESET packet (empty segment with RST flag set) either to
andrewbonney	0:ec559500a63f	1184	* abort a connection or to show that there is no matching local connection
andrewbonney	0:ec559500a63f	1185	* for a received segment.
andrewbonney	0:ec559500a63f	1186	*
andrewbonney	0:ec559500a63f	1187	* Called by tcp_abort() (to abort a local connection), tcp_input() (if no
andrewbonney	0:ec559500a63f	1188	* matching local pcb was found), tcp_listen_input() (if incoming segment
andrewbonney	0:ec559500a63f	1189	* has ACK flag set) and tcp_process() (received segment in the wrong state)
andrewbonney	0:ec559500a63f	1190	*
andrewbonney	0:ec559500a63f	1191	* Since a RST segment is in most cases not sent for an active connection,
andrewbonney	0:ec559500a63f	1192	* tcp_rst() has a number of arguments that are taken from a tcp_pcb for
andrewbonney	0:ec559500a63f	1193	* most other segment output functions.
andrewbonney	0:ec559500a63f	1194	*
andrewbonney	0:ec559500a63f	1195	* @param seqno the sequence number to use for the outgoing segment
andrewbonney	0:ec559500a63f	1196	* @param ackno the acknowledge number to use for the outgoing segment
andrewbonney	0:ec559500a63f	1197	* @param local_ip the local IP address to send the segment from
andrewbonney	0:ec559500a63f	1198	* @param remote_ip the remote IP address to send the segment to
andrewbonney	0:ec559500a63f	1199	* @param local_port the local TCP port to send the segment from
andrewbonney	0:ec559500a63f	1200	* @param remote_port the remote TCP port to send the segment to
andrewbonney	0:ec559500a63f	1201	*/
andrewbonney	0:ec559500a63f	1202	void
andrewbonney	0:ec559500a63f	1203	tcp_rst(u32_t seqno, u32_t ackno,
andrewbonney	0:ec559500a63f	1204	ip_addr_t local_ip, ip_addr_t remote_ip,
andrewbonney	0:ec559500a63f	1205	u16_t local_port, u16_t remote_port)
andrewbonney	0:ec559500a63f	1206	{
andrewbonney	0:ec559500a63f	1207	struct pbuf *p;
andrewbonney	0:ec559500a63f	1208	struct tcp_hdr *tcphdr;
andrewbonney	0:ec559500a63f	1209	p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
andrewbonney	0:ec559500a63f	1210	if (p == NULL) {
andrewbonney	0:ec559500a63f	1211	LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
andrewbonney	0:ec559500a63f	1212	return;
andrewbonney	0:ec559500a63f	1213	}
andrewbonney	0:ec559500a63f	1214	LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
andrewbonney	0:ec559500a63f	1215	(p->len >= sizeof(struct tcp_hdr)));
andrewbonney	0:ec559500a63f	1216
andrewbonney	0:ec559500a63f	1217	tcphdr = (struct tcp_hdr *)p->payload;
andrewbonney	0:ec559500a63f	1218	tcphdr->src = htons(local_port);
andrewbonney	0:ec559500a63f	1219	tcphdr->dest = htons(remote_port);
andrewbonney	0:ec559500a63f	1220	tcphdr->seqno = htonl(seqno);
andrewbonney	0:ec559500a63f	1221	tcphdr->ackno = htonl(ackno);
andrewbonney	0:ec559500a63f	1222	TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST \| TCP_ACK);
andrewbonney	0:ec559500a63f	1223	tcphdr->wnd = PP_HTONS(TCP_WND);
andrewbonney	0:ec559500a63f	1224	tcphdr->chksum = 0;
andrewbonney	0:ec559500a63f	1225	tcphdr->urgp = 0;
andrewbonney	0:ec559500a63f	1226
andrewbonney	0:ec559500a63f	1227	#if CHECKSUM_GEN_TCP
andrewbonney	0:ec559500a63f	1228	tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
andrewbonney	0:ec559500a63f	1229	IP_PROTO_TCP, p->tot_len);
andrewbonney	0:ec559500a63f	1230	#endif
andrewbonney	0:ec559500a63f	1231	TCP_STATS_INC(tcp.xmit);
andrewbonney	0:ec559500a63f	1232	snmp_inc_tcpoutrsts();
andrewbonney	0:ec559500a63f	1233	/* Send output with hardcoded TTL since we have no access to the pcb */
andrewbonney	0:ec559500a63f	1234	ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
andrewbonney	0:ec559500a63f	1235	pbuf_free(p);
andrewbonney	0:ec559500a63f	1236	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
andrewbonney	0:ec559500a63f	1237	}
andrewbonney	0:ec559500a63f	1238
andrewbonney	0:ec559500a63f	1239	/**
andrewbonney	0:ec559500a63f	1240	* Requeue all unacked segments for retransmission
andrewbonney	0:ec559500a63f	1241	*
andrewbonney	0:ec559500a63f	1242	* Called by tcp_slowtmr() for slow retransmission.
andrewbonney	0:ec559500a63f	1243	*
andrewbonney	0:ec559500a63f	1244	* @param pcb the tcp_pcb for which to re-enqueue all unacked segments
andrewbonney	0:ec559500a63f	1245	*/
andrewbonney	0:ec559500a63f	1246	void
andrewbonney	0:ec559500a63f	1247	tcp_rexmit_rto(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	1248	{
andrewbonney	0:ec559500a63f	1249	struct tcp_seg *seg;
andrewbonney	0:ec559500a63f	1250
andrewbonney	0:ec559500a63f	1251	if (pcb->unacked == NULL) {
andrewbonney	0:ec559500a63f	1252	return;
andrewbonney	0:ec559500a63f	1253	}
andrewbonney	0:ec559500a63f	1254
andrewbonney	0:ec559500a63f	1255	/* Move all unacked segments to the head of the unsent queue */
andrewbonney	0:ec559500a63f	1256	for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
andrewbonney	0:ec559500a63f	1257	/* concatenate unsent queue after unacked queue */
andrewbonney	0:ec559500a63f	1258	seg->next = pcb->unsent;
andrewbonney	0:ec559500a63f	1259	/* unsent queue is the concatenated queue (of unacked, unsent) */
andrewbonney	0:ec559500a63f	1260	pcb->unsent = pcb->unacked;
andrewbonney	0:ec559500a63f	1261	/* unacked queue is now empty */
andrewbonney	0:ec559500a63f	1262	pcb->unacked = NULL;
andrewbonney	0:ec559500a63f	1263
andrewbonney	0:ec559500a63f	1264	/* increment number of retransmissions */
andrewbonney	0:ec559500a63f	1265	++pcb->nrtx;
andrewbonney	0:ec559500a63f	1266
andrewbonney	0:ec559500a63f	1267	/* Don't take any RTT measurements after retransmitting. */
andrewbonney	0:ec559500a63f	1268	pcb->rttest = 0;
andrewbonney	0:ec559500a63f	1269
andrewbonney	0:ec559500a63f	1270	/* Do the actual retransmission */
andrewbonney	0:ec559500a63f	1271	tcp_output(pcb);
andrewbonney	0:ec559500a63f	1272	}
andrewbonney	0:ec559500a63f	1273
andrewbonney	0:ec559500a63f	1274	/**
andrewbonney	0:ec559500a63f	1275	* Requeue the first unacked segment for retransmission
andrewbonney	0:ec559500a63f	1276	*
andrewbonney	0:ec559500a63f	1277	* Called by tcp_receive() for fast retramsmit.
andrewbonney	0:ec559500a63f	1278	*
andrewbonney	0:ec559500a63f	1279	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
andrewbonney	0:ec559500a63f	1280	*/
andrewbonney	0:ec559500a63f	1281	void
andrewbonney	0:ec559500a63f	1282	tcp_rexmit(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	1283	{
andrewbonney	0:ec559500a63f	1284	struct tcp_seg *seg;
andrewbonney	0:ec559500a63f	1285	struct tcp_seg **cur_seg;
andrewbonney	0:ec559500a63f	1286
andrewbonney	0:ec559500a63f	1287	if (pcb->unacked == NULL) {
andrewbonney	0:ec559500a63f	1288	return;
andrewbonney	0:ec559500a63f	1289	}
andrewbonney	0:ec559500a63f	1290
andrewbonney	0:ec559500a63f	1291	/* Move the first unacked segment to the unsent queue */
andrewbonney	0:ec559500a63f	1292	/* Keep the unsent queue sorted. */
andrewbonney	0:ec559500a63f	1293	seg = pcb->unacked;
andrewbonney	0:ec559500a63f	1294	pcb->unacked = seg->next;
andrewbonney	0:ec559500a63f	1295
andrewbonney	0:ec559500a63f	1296	cur_seg = &(pcb->unsent);
andrewbonney	0:ec559500a63f	1297	while (*cur_seg &&
andrewbonney	0:ec559500a63f	1298	TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
andrewbonney	0:ec559500a63f	1299	cur_seg = &((*cur_seg)->next );
andrewbonney	0:ec559500a63f	1300	}
andrewbonney	0:ec559500a63f	1301	seg->next = *cur_seg;
andrewbonney	0:ec559500a63f	1302	*cur_seg = seg;
andrewbonney	0:ec559500a63f	1303
andrewbonney	0:ec559500a63f	1304	++pcb->nrtx;
andrewbonney	0:ec559500a63f	1305
andrewbonney	0:ec559500a63f	1306	/* Don't take any rtt measurements after retransmitting. */
andrewbonney	0:ec559500a63f	1307	pcb->rttest = 0;
andrewbonney	0:ec559500a63f	1308
andrewbonney	0:ec559500a63f	1309	/* Do the actual retransmission. */
andrewbonney	0:ec559500a63f	1310	snmp_inc_tcpretranssegs();
andrewbonney	0:ec559500a63f	1311	/* No need to call tcp_output: we are always called from tcp_input()
andrewbonney	0:ec559500a63f	1312	and thus tcp_output directly returns. */
andrewbonney	0:ec559500a63f	1313	}
andrewbonney	0:ec559500a63f	1314
andrewbonney	0:ec559500a63f	1315
andrewbonney	0:ec559500a63f	1316	/**
andrewbonney	0:ec559500a63f	1317	* Handle retransmission after three dupacks received
andrewbonney	0:ec559500a63f	1318	*
andrewbonney	0:ec559500a63f	1319	* @param pcb the tcp_pcb for which to retransmit the first unacked segment
andrewbonney	0:ec559500a63f	1320	*/
andrewbonney	0:ec559500a63f	1321	void
andrewbonney	0:ec559500a63f	1322	tcp_rexmit_fast(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	1323	{
andrewbonney	0:ec559500a63f	1324	if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
andrewbonney	0:ec559500a63f	1325	/* This is fast retransmit. Retransmit the first unacked segment. */
andrewbonney	0:ec559500a63f	1326	LWIP_DEBUGF(TCP_FR_DEBUG,
andrewbonney	0:ec559500a63f	1327	("tcp_receive: dupacks %"U16_F" (%"U32_F
andrewbonney	0:ec559500a63f	1328	"), fast retransmit %"U32_F"\n",
andrewbonney	0:ec559500a63f	1329	(u16_t)pcb->dupacks, pcb->lastack,
andrewbonney	0:ec559500a63f	1330	ntohl(pcb->unacked->tcphdr->seqno)));
andrewbonney	0:ec559500a63f	1331	tcp_rexmit(pcb);
andrewbonney	0:ec559500a63f	1332
andrewbonney	0:ec559500a63f	1333	/* Set ssthresh to half of the minimum of the current
andrewbonney	0:ec559500a63f	1334	* cwnd and the advertised window */
andrewbonney	0:ec559500a63f	1335	if (pcb->cwnd > pcb->snd_wnd) {
andrewbonney	0:ec559500a63f	1336	pcb->ssthresh = pcb->snd_wnd / 2;
andrewbonney	0:ec559500a63f	1337	} else {
andrewbonney	0:ec559500a63f	1338	pcb->ssthresh = pcb->cwnd / 2;
andrewbonney	0:ec559500a63f	1339	}
andrewbonney	0:ec559500a63f	1340
andrewbonney	0:ec559500a63f	1341	/* The minimum value for ssthresh should be 2 MSS */
andrewbonney	0:ec559500a63f	1342	if (pcb->ssthresh < 2*pcb->mss) {
andrewbonney	0:ec559500a63f	1343	LWIP_DEBUGF(TCP_FR_DEBUG,
andrewbonney	0:ec559500a63f	1344	("tcp_receive: The minimum value for ssthresh %"U16_F
andrewbonney	0:ec559500a63f	1345	" should be min 2 mss %"U16_F"...\n",
andrewbonney	0:ec559500a63f	1346	pcb->ssthresh, 2*pcb->mss));
andrewbonney	0:ec559500a63f	1347	pcb->ssthresh = 2*pcb->mss;
andrewbonney	0:ec559500a63f	1348	}
andrewbonney	0:ec559500a63f	1349
andrewbonney	0:ec559500a63f	1350	pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
andrewbonney	0:ec559500a63f	1351	pcb->flags \|= TF_INFR;
andrewbonney	0:ec559500a63f	1352	}
andrewbonney	0:ec559500a63f	1353	}
andrewbonney	0:ec559500a63f	1354
andrewbonney	0:ec559500a63f	1355
andrewbonney	0:ec559500a63f	1356	/**
andrewbonney	0:ec559500a63f	1357	* Send keepalive packets to keep a connection active although
andrewbonney	0:ec559500a63f	1358	* no data is sent over it.
andrewbonney	0:ec559500a63f	1359	*
andrewbonney	0:ec559500a63f	1360	* Called by tcp_slowtmr()
andrewbonney	0:ec559500a63f	1361	*
andrewbonney	0:ec559500a63f	1362	* @param pcb the tcp_pcb for which to send a keepalive packet
andrewbonney	0:ec559500a63f	1363	*/
andrewbonney	0:ec559500a63f	1364	void
andrewbonney	0:ec559500a63f	1365	tcp_keepalive(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	1366	{
andrewbonney	0:ec559500a63f	1367	struct pbuf *p;
andrewbonney	0:ec559500a63f	1368	struct tcp_hdr *tcphdr;
andrewbonney	0:ec559500a63f	1369
andrewbonney	0:ec559500a63f	1370	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
andrewbonney	0:ec559500a63f	1371	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
andrewbonney	0:ec559500a63f	1372	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
andrewbonney	0:ec559500a63f	1373
andrewbonney	0:ec559500a63f	1374	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
andrewbonney	0:ec559500a63f	1375	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
andrewbonney	0:ec559500a63f	1376
andrewbonney	0:ec559500a63f	1377	p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
andrewbonney	0:ec559500a63f	1378	if(p == NULL) {
andrewbonney	0:ec559500a63f	1379	LWIP_DEBUGF(TCP_DEBUG,
andrewbonney	0:ec559500a63f	1380	("tcp_keepalive: could not allocate memory for pbuf\n"));
andrewbonney	0:ec559500a63f	1381	return;
andrewbonney	0:ec559500a63f	1382	}
andrewbonney	0:ec559500a63f	1383	tcphdr = (struct tcp_hdr *)p->payload;
andrewbonney	0:ec559500a63f	1384
andrewbonney	0:ec559500a63f	1385	#if CHECKSUM_GEN_TCP
andrewbonney	0:ec559500a63f	1386	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
andrewbonney	0:ec559500a63f	1387	IP_PROTO_TCP, p->tot_len);
andrewbonney	0:ec559500a63f	1388	#endif
andrewbonney	0:ec559500a63f	1389	TCP_STATS_INC(tcp.xmit);
andrewbonney	0:ec559500a63f	1390
andrewbonney	0:ec559500a63f	1391	/* Send output to IP */
andrewbonney	0:ec559500a63f	1392	#if LWIP_NETIF_HWADDRHINT
andrewbonney	0:ec559500a63f	1393	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
andrewbonney	0:ec559500a63f	1394	&(pcb->addr_hint));
andrewbonney	0:ec559500a63f	1395	#else /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	1396	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
andrewbonney	0:ec559500a63f	1397	#endif /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	1398
andrewbonney	0:ec559500a63f	1399	pbuf_free(p);
andrewbonney	0:ec559500a63f	1400
andrewbonney	0:ec559500a63f	1401	LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
andrewbonney	0:ec559500a63f	1402	pcb->snd_nxt - 1, pcb->rcv_nxt));
andrewbonney	0:ec559500a63f	1403	}
andrewbonney	0:ec559500a63f	1404
andrewbonney	0:ec559500a63f	1405
andrewbonney	0:ec559500a63f	1406	/**
andrewbonney	0:ec559500a63f	1407	* Send persist timer zero-window probes to keep a connection active
andrewbonney	0:ec559500a63f	1408	* when a window update is lost.
andrewbonney	0:ec559500a63f	1409	*
andrewbonney	0:ec559500a63f	1410	* Called by tcp_slowtmr()
andrewbonney	0:ec559500a63f	1411	*
andrewbonney	0:ec559500a63f	1412	* @param pcb the tcp_pcb for which to send a zero-window probe packet
andrewbonney	0:ec559500a63f	1413	*/
andrewbonney	0:ec559500a63f	1414	void
andrewbonney	0:ec559500a63f	1415	tcp_zero_window_probe(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	1416	{
andrewbonney	0:ec559500a63f	1417	struct pbuf *p;
andrewbonney	0:ec559500a63f	1418	struct tcp_hdr *tcphdr;
andrewbonney	0:ec559500a63f	1419	struct tcp_seg *seg;
andrewbonney	0:ec559500a63f	1420	u16_t len;
andrewbonney	0:ec559500a63f	1421	u8_t is_fin;
andrewbonney	0:ec559500a63f	1422
andrewbonney	0:ec559500a63f	1423	LWIP_DEBUGF(TCP_DEBUG,
andrewbonney	0:ec559500a63f	1424	("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
andrewbonney	0:ec559500a63f	1425	U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
andrewbonney	0:ec559500a63f	1426	ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
andrewbonney	0:ec559500a63f	1427	ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
andrewbonney	0:ec559500a63f	1428
andrewbonney	0:ec559500a63f	1429	LWIP_DEBUGF(TCP_DEBUG,
andrewbonney	0:ec559500a63f	1430	("tcp_zero_window_probe: tcp_ticks %"U32_F
andrewbonney	0:ec559500a63f	1431	" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
andrewbonney	0:ec559500a63f	1432	tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
andrewbonney	0:ec559500a63f	1433
andrewbonney	0:ec559500a63f	1434	seg = pcb->unacked;
andrewbonney	0:ec559500a63f	1435
andrewbonney	0:ec559500a63f	1436	if(seg == NULL) {
andrewbonney	0:ec559500a63f	1437	seg = pcb->unsent;
andrewbonney	0:ec559500a63f	1438	}
andrewbonney	0:ec559500a63f	1439	if(seg == NULL) {
andrewbonney	0:ec559500a63f	1440	return;
andrewbonney	0:ec559500a63f	1441	}
andrewbonney	0:ec559500a63f	1442
andrewbonney	0:ec559500a63f	1443	is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
andrewbonney	0:ec559500a63f	1444	/* we want to send one seqno: either FIN or data (no options) */
andrewbonney	0:ec559500a63f	1445	len = is_fin ? 0 : 1;
andrewbonney	0:ec559500a63f	1446
andrewbonney	0:ec559500a63f	1447	p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
andrewbonney	0:ec559500a63f	1448	if(p == NULL) {
andrewbonney	0:ec559500a63f	1449	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
andrewbonney	0:ec559500a63f	1450	return;
andrewbonney	0:ec559500a63f	1451	}
andrewbonney	0:ec559500a63f	1452	tcphdr = (struct tcp_hdr *)p->payload;
andrewbonney	0:ec559500a63f	1453
andrewbonney	0:ec559500a63f	1454	if (is_fin) {
andrewbonney	0:ec559500a63f	1455	/* FIN segment, no data */
andrewbonney	0:ec559500a63f	1456	TCPH_FLAGS_SET(tcphdr, TCP_ACK \| TCP_FIN);
andrewbonney	0:ec559500a63f	1457	} else {
andrewbonney	0:ec559500a63f	1458	/* Data segment, copy in one byte from the head of the unacked queue */
andrewbonney	0:ec559500a63f	1459	((char )p->payload + TCP_HLEN) = (char )seg->dataptr;
andrewbonney	0:ec559500a63f	1460	}
andrewbonney	0:ec559500a63f	1461
andrewbonney	0:ec559500a63f	1462	#if CHECKSUM_GEN_TCP
andrewbonney	0:ec559500a63f	1463	tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
andrewbonney	0:ec559500a63f	1464	IP_PROTO_TCP, p->tot_len);
andrewbonney	0:ec559500a63f	1465	#endif
andrewbonney	0:ec559500a63f	1466	TCP_STATS_INC(tcp.xmit);
andrewbonney	0:ec559500a63f	1467
andrewbonney	0:ec559500a63f	1468	/* Send output to IP */
andrewbonney	0:ec559500a63f	1469	#if LWIP_NETIF_HWADDRHINT
andrewbonney	0:ec559500a63f	1470	ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
andrewbonney	0:ec559500a63f	1471	&(pcb->addr_hint));
andrewbonney	0:ec559500a63f	1472	#else /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	1473	ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
andrewbonney	0:ec559500a63f	1474	#endif /* LWIP_NETIF_HWADDRHINT*/
andrewbonney	0:ec559500a63f	1475
andrewbonney	0:ec559500a63f	1476	pbuf_free(p);
andrewbonney	0:ec559500a63f	1477
andrewbonney	0:ec559500a63f	1478	LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
andrewbonney	0:ec559500a63f	1479	" ackno %"U32_F".\n",
andrewbonney	0:ec559500a63f	1480	pcb->snd_nxt - 1, pcb->rcv_nxt));
andrewbonney	0:ec559500a63f	1481	}
andrewbonney	0:ec559500a63f	1482	#endif /* LWIP_TCP */

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Type:	Library
Created:	08 Apr 2011
Imports:	86
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	3

lwip/core/tcp_out.c@0:ec559500a63f, 2011-04-08 (annotated)

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