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lwip/core/tcp_in.c@0:d616ece2d859, 2010-09-18 (annotated)

Committer:: mbed714
Date:: Sat Sep 18 23:05:49 2010 +0000
Revision:: 0:d616ece2d859

Who changed what in which revision?

User	Revision	Line number	New contents of line
mbed714	0:d616ece2d859	1	/**
mbed714	0:d616ece2d859	2	* @file
mbed714	0:d616ece2d859	3	* Transmission Control Protocol, incoming traffic
mbed714	0:d616ece2d859	4	*
mbed714	0:d616ece2d859	5	* The input processing functions of the TCP layer.
mbed714	0:d616ece2d859	6	*
mbed714	0:d616ece2d859	7	* These functions are generally called in the order (ip_input() ->)
mbed714	0:d616ece2d859	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
mbed714	0:d616ece2d859	9	*
mbed714	0:d616ece2d859	10	*/
mbed714	0:d616ece2d859	11
mbed714	0:d616ece2d859	12	/*
mbed714	0:d616ece2d859	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
mbed714	0:d616ece2d859	14	* All rights reserved.
mbed714	0:d616ece2d859	15	*
mbed714	0:d616ece2d859	16	* Redistribution and use in source and binary forms, with or without modification,
mbed714	0:d616ece2d859	17	* are permitted provided that the following conditions are met:
mbed714	0:d616ece2d859	18	*
mbed714	0:d616ece2d859	19	* 1. Redistributions of source code must retain the above copyright notice,
mbed714	0:d616ece2d859	20	* this list of conditions and the following disclaimer.
mbed714	0:d616ece2d859	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
mbed714	0:d616ece2d859	22	* this list of conditions and the following disclaimer in the documentation
mbed714	0:d616ece2d859	23	* and/or other materials provided with the distribution.
mbed714	0:d616ece2d859	24	* 3. The name of the author may not be used to endorse or promote products
mbed714	0:d616ece2d859	25	* derived from this software without specific prior written permission.
mbed714	0:d616ece2d859	26	*
mbed714	0:d616ece2d859	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
mbed714	0:d616ece2d859	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
mbed714	0:d616ece2d859	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
mbed714	0:d616ece2d859	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
mbed714	0:d616ece2d859	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
mbed714	0:d616ece2d859	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
mbed714	0:d616ece2d859	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
mbed714	0:d616ece2d859	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
mbed714	0:d616ece2d859	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
mbed714	0:d616ece2d859	36	* OF SUCH DAMAGE.
mbed714	0:d616ece2d859	37	*
mbed714	0:d616ece2d859	38	* This file is part of the lwIP TCP/IP stack.
mbed714	0:d616ece2d859	39	*
mbed714	0:d616ece2d859	40	* Author: Adam Dunkels <adam@sics.se>
mbed714	0:d616ece2d859	41	*
mbed714	0:d616ece2d859	42	*/
mbed714	0:d616ece2d859	43
mbed714	0:d616ece2d859	44	#include "lwip/opt.h"
mbed714	0:d616ece2d859	45
mbed714	0:d616ece2d859	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
mbed714	0:d616ece2d859	47
mbed714	0:d616ece2d859	48	#include "lwip/tcp_impl.h"
mbed714	0:d616ece2d859	49	#include "lwip/def.h"
mbed714	0:d616ece2d859	50	#include "lwip/ip_addr.h"
mbed714	0:d616ece2d859	51	#include "lwip/netif.h"
mbed714	0:d616ece2d859	52	#include "lwip/mem.h"
mbed714	0:d616ece2d859	53	#include "lwip/memp.h"
mbed714	0:d616ece2d859	54	#include "lwip/inet_chksum.h"
mbed714	0:d616ece2d859	55	#include "lwip/stats.h"
mbed714	0:d616ece2d859	56	#include "lwip/snmp.h"
mbed714	0:d616ece2d859	57	#include "arch/perf.h"
mbed714	0:d616ece2d859	58
mbed714	0:d616ece2d859	59	/* These variables are global to all functions involved in the input
mbed714	0:d616ece2d859	60	processing of TCP segments. They are set by the tcp_input()
mbed714	0:d616ece2d859	61	function. */
mbed714	0:d616ece2d859	62	static struct tcp_seg inseg;
mbed714	0:d616ece2d859	63	static struct tcp_hdr *tcphdr;
mbed714	0:d616ece2d859	64	static struct ip_hdr *iphdr;
mbed714	0:d616ece2d859	65	static u32_t seqno, ackno;
mbed714	0:d616ece2d859	66	static u8_t flags;
mbed714	0:d616ece2d859	67	static u16_t tcplen;
mbed714	0:d616ece2d859	68
mbed714	0:d616ece2d859	69	static u8_t recv_flags;
mbed714	0:d616ece2d859	70	static struct pbuf *recv_data;
mbed714	0:d616ece2d859	71
mbed714	0:d616ece2d859	72	struct tcp_pcb *tcp_input_pcb;
mbed714	0:d616ece2d859	73
mbed714	0:d616ece2d859	74	/* Forward declarations. */
mbed714	0:d616ece2d859	75	static err_t tcp_process(struct tcp_pcb *pcb);
mbed714	0:d616ece2d859	76	static void tcp_receive(struct tcp_pcb *pcb);
mbed714	0:d616ece2d859	77	static void tcp_parseopt(struct tcp_pcb *pcb);
mbed714	0:d616ece2d859	78
mbed714	0:d616ece2d859	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
mbed714	0:d616ece2d859	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
mbed714	0:d616ece2d859	81
mbed714	0:d616ece2d859	82	/**
mbed714	0:d616ece2d859	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
mbed714	0:d616ece2d859	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
mbed714	0:d616ece2d859	85	* the TCP finite state machine. This function is called by the IP layer (in
mbed714	0:d616ece2d859	86	* ip_input()).
mbed714	0:d616ece2d859	87	*
mbed714	0:d616ece2d859	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
mbed714	0:d616ece2d859	89	* @param inp network interface on which this segment was received
mbed714	0:d616ece2d859	90	*/
mbed714	0:d616ece2d859	91	void
mbed714	0:d616ece2d859	92	tcp_input(struct pbuf p, struct netif inp)
mbed714	0:d616ece2d859	93	{
mbed714	0:d616ece2d859	94	struct tcp_pcb pcb, prev;
mbed714	0:d616ece2d859	95	struct tcp_pcb_listen *lpcb;
mbed714	0:d616ece2d859	96	#if SO_REUSE
mbed714	0:d616ece2d859	97	struct tcp_pcb *lpcb_prev = NULL;
mbed714	0:d616ece2d859	98	struct tcp_pcb_listen *lpcb_any = NULL;
mbed714	0:d616ece2d859	99	#endif /* SO_REUSE */
mbed714	0:d616ece2d859	100	u8_t hdrlen;
mbed714	0:d616ece2d859	101	err_t err;
mbed714	0:d616ece2d859	102
mbed714	0:d616ece2d859	103	PERF_START;
mbed714	0:d616ece2d859	104
mbed714	0:d616ece2d859	105	TCP_STATS_INC(tcp.recv);
mbed714	0:d616ece2d859	106	snmp_inc_tcpinsegs();
mbed714	0:d616ece2d859	107
mbed714	0:d616ece2d859	108	iphdr = (struct ip_hdr *)p->payload;
mbed714	0:d616ece2d859	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
mbed714	0:d616ece2d859	110
mbed714	0:d616ece2d859	111	#if TCP_INPUT_DEBUG
mbed714	0:d616ece2d859	112	tcp_debug_print(tcphdr);
mbed714	0:d616ece2d859	113	#endif
mbed714	0:d616ece2d859	114
mbed714	0:d616ece2d859	115	/* remove header from payload */
mbed714	0:d616ece2d859	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
mbed714	0:d616ece2d859	117	/* drop short packets */
mbed714	0:d616ece2d859	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
mbed714	0:d616ece2d859	119	TCP_STATS_INC(tcp.lenerr);
mbed714	0:d616ece2d859	120	TCP_STATS_INC(tcp.drop);
mbed714	0:d616ece2d859	121	snmp_inc_tcpinerrs();
mbed714	0:d616ece2d859	122	pbuf_free(p);
mbed714	0:d616ece2d859	123	return;
mbed714	0:d616ece2d859	124	}
mbed714	0:d616ece2d859	125
mbed714	0:d616ece2d859	126	/* Don't even process incoming broadcasts/multicasts. */
mbed714	0:d616ece2d859	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
mbed714	0:d616ece2d859	128	ip_addr_ismulticast(&current_iphdr_dest)) {
mbed714	0:d616ece2d859	129	TCP_STATS_INC(tcp.proterr);
mbed714	0:d616ece2d859	130	TCP_STATS_INC(tcp.drop);
mbed714	0:d616ece2d859	131	snmp_inc_tcpinerrs();
mbed714	0:d616ece2d859	132	pbuf_free(p);
mbed714	0:d616ece2d859	133	return;
mbed714	0:d616ece2d859	134	}
mbed714	0:d616ece2d859	135
mbed714	0:d616ece2d859	136	#if CHECKSUM_CHECK_TCP
mbed714	0:d616ece2d859	137	/* Verify TCP checksum. */
mbed714	0:d616ece2d859	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
mbed714	0:d616ece2d859	139	IP_PROTO_TCP, p->tot_len) != 0) {
mbed714	0:d616ece2d859	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
mbed714	0:d616ece2d859	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
mbed714	0:d616ece2d859	142	IP_PROTO_TCP, p->tot_len)));
mbed714	0:d616ece2d859	143	#if TCP_DEBUG
mbed714	0:d616ece2d859	144	tcp_debug_print(tcphdr);
mbed714	0:d616ece2d859	145	#endif /* TCP_DEBUG */
mbed714	0:d616ece2d859	146	TCP_STATS_INC(tcp.chkerr);
mbed714	0:d616ece2d859	147	TCP_STATS_INC(tcp.drop);
mbed714	0:d616ece2d859	148	snmp_inc_tcpinerrs();
mbed714	0:d616ece2d859	149	pbuf_free(p);
mbed714	0:d616ece2d859	150	return;
mbed714	0:d616ece2d859	151	}
mbed714	0:d616ece2d859	152	#endif
mbed714	0:d616ece2d859	153
mbed714	0:d616ece2d859	154	/* Move the payload pointer in the pbuf so that it points to the
mbed714	0:d616ece2d859	155	TCP data instead of the TCP header. */
mbed714	0:d616ece2d859	156	hdrlen = TCPH_HDRLEN(tcphdr);
mbed714	0:d616ece2d859	157	if(pbuf_header(p, -(hdrlen * 4))){
mbed714	0:d616ece2d859	158	/* drop short packets */
mbed714	0:d616ece2d859	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
mbed714	0:d616ece2d859	160	TCP_STATS_INC(tcp.lenerr);
mbed714	0:d616ece2d859	161	TCP_STATS_INC(tcp.drop);
mbed714	0:d616ece2d859	162	snmp_inc_tcpinerrs();
mbed714	0:d616ece2d859	163	pbuf_free(p);
mbed714	0:d616ece2d859	164	return;
mbed714	0:d616ece2d859	165	}
mbed714	0:d616ece2d859	166
mbed714	0:d616ece2d859	167	/* Convert fields in TCP header to host byte order. */
mbed714	0:d616ece2d859	168	tcphdr->src = ntohs(tcphdr->src);
mbed714	0:d616ece2d859	169	tcphdr->dest = ntohs(tcphdr->dest);
mbed714	0:d616ece2d859	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
mbed714	0:d616ece2d859	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
mbed714	0:d616ece2d859	172	tcphdr->wnd = ntohs(tcphdr->wnd);
mbed714	0:d616ece2d859	173
mbed714	0:d616ece2d859	174	flags = TCPH_FLAGS(tcphdr);
mbed714	0:d616ece2d859	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
mbed714	0:d616ece2d859	176
mbed714	0:d616ece2d859	177	/* Demultiplex an incoming segment. First, we check if it is destined
mbed714	0:d616ece2d859	178	for an active connection. */
mbed714	0:d616ece2d859	179	prev = NULL;
mbed714	0:d616ece2d859	180
mbed714	0:d616ece2d859	181
mbed714	0:d616ece2d859	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
mbed714	0:d616ece2d859	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
mbed714	0:d616ece2d859	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
mbed714	0:d616ece2d859	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
mbed714	0:d616ece2d859	186	if (pcb->remote_port == tcphdr->src &&
mbed714	0:d616ece2d859	187	pcb->local_port == tcphdr->dest &&
mbed714	0:d616ece2d859	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
mbed714	0:d616ece2d859	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
mbed714	0:d616ece2d859	190
mbed714	0:d616ece2d859	191	/* Move this PCB to the front of the list so that subsequent
mbed714	0:d616ece2d859	192	lookups will be faster (we exploit locality in TCP segment
mbed714	0:d616ece2d859	193	arrivals). */
mbed714	0:d616ece2d859	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
mbed714	0:d616ece2d859	195	if (prev != NULL) {
mbed714	0:d616ece2d859	196	prev->next = pcb->next;
mbed714	0:d616ece2d859	197	pcb->next = tcp_active_pcbs;
mbed714	0:d616ece2d859	198	tcp_active_pcbs = pcb;
mbed714	0:d616ece2d859	199	}
mbed714	0:d616ece2d859	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
mbed714	0:d616ece2d859	201	break;
mbed714	0:d616ece2d859	202	}
mbed714	0:d616ece2d859	203	prev = pcb;
mbed714	0:d616ece2d859	204	}
mbed714	0:d616ece2d859	205
mbed714	0:d616ece2d859	206	if (pcb == NULL) {
mbed714	0:d616ece2d859	207	/* If it did not go to an active connection, we check the connections
mbed714	0:d616ece2d859	208	in the TIME-WAIT state. */
mbed714	0:d616ece2d859	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
mbed714	0:d616ece2d859	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
mbed714	0:d616ece2d859	211	if (pcb->remote_port == tcphdr->src &&
mbed714	0:d616ece2d859	212	pcb->local_port == tcphdr->dest &&
mbed714	0:d616ece2d859	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
mbed714	0:d616ece2d859	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
mbed714	0:d616ece2d859	215	/* We don't really care enough to move this PCB to the front
mbed714	0:d616ece2d859	216	of the list since we are not very likely to receive that
mbed714	0:d616ece2d859	217	many segments for connections in TIME-WAIT. */
mbed714	0:d616ece2d859	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
mbed714	0:d616ece2d859	219	tcp_timewait_input(pcb);
mbed714	0:d616ece2d859	220	pbuf_free(p);
mbed714	0:d616ece2d859	221	return;
mbed714	0:d616ece2d859	222	}
mbed714	0:d616ece2d859	223	}
mbed714	0:d616ece2d859	224
mbed714	0:d616ece2d859	225	/* Finally, if we still did not get a match, we check all PCBs that
mbed714	0:d616ece2d859	226	are LISTENing for incoming connections. */
mbed714	0:d616ece2d859	227	prev = NULL;
mbed714	0:d616ece2d859	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
mbed714	0:d616ece2d859	229	if (lpcb->local_port == tcphdr->dest) {
mbed714	0:d616ece2d859	230	#if SO_REUSE
mbed714	0:d616ece2d859	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
mbed714	0:d616ece2d859	232	/* found an exact match */
mbed714	0:d616ece2d859	233	break;
mbed714	0:d616ece2d859	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
mbed714	0:d616ece2d859	235	/* found an ANY-match */
mbed714	0:d616ece2d859	236	lpcb_any = lpcb;
mbed714	0:d616ece2d859	237	lpcb_prev = prev;
mbed714	0:d616ece2d859	238	}
mbed714	0:d616ece2d859	239	#else /* SO_REUSE */
mbed714	0:d616ece2d859	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
mbed714	0:d616ece2d859	241	ip_addr_isany(&(lpcb->local_ip))) {
mbed714	0:d616ece2d859	242	/* found a match */
mbed714	0:d616ece2d859	243	break;
mbed714	0:d616ece2d859	244	}
mbed714	0:d616ece2d859	245	#endif /* SO_REUSE */
mbed714	0:d616ece2d859	246	}
mbed714	0:d616ece2d859	247	prev = (struct tcp_pcb *)lpcb;
mbed714	0:d616ece2d859	248	}
mbed714	0:d616ece2d859	249	#if SO_REUSE
mbed714	0:d616ece2d859	250	/* first try specific local IP */
mbed714	0:d616ece2d859	251	if (lpcb == NULL) {
mbed714	0:d616ece2d859	252	/* only pass to ANY if no specific local IP has been found */
mbed714	0:d616ece2d859	253	lpcb = lpcb_any;
mbed714	0:d616ece2d859	254	prev = lpcb_prev;
mbed714	0:d616ece2d859	255	}
mbed714	0:d616ece2d859	256	#endif /* SO_REUSE */
mbed714	0:d616ece2d859	257	if (lpcb != NULL) {
mbed714	0:d616ece2d859	258	/* Move this PCB to the front of the list so that subsequent
mbed714	0:d616ece2d859	259	lookups will be faster (we exploit locality in TCP segment
mbed714	0:d616ece2d859	260	arrivals). */
mbed714	0:d616ece2d859	261	if (prev != NULL) {
mbed714	0:d616ece2d859	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
mbed714	0:d616ece2d859	263	/* our successor is the remainder of the listening list */
mbed714	0:d616ece2d859	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
mbed714	0:d616ece2d859	265	/* put this listening pcb at the head of the listening list */
mbed714	0:d616ece2d859	266	tcp_listen_pcbs.listen_pcbs = lpcb;
mbed714	0:d616ece2d859	267	}
mbed714	0:d616ece2d859	268
mbed714	0:d616ece2d859	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
mbed714	0:d616ece2d859	270	tcp_listen_input(lpcb);
mbed714	0:d616ece2d859	271	pbuf_free(p);
mbed714	0:d616ece2d859	272	return;
mbed714	0:d616ece2d859	273	}
mbed714	0:d616ece2d859	274	}
mbed714	0:d616ece2d859	275
mbed714	0:d616ece2d859	276	#if TCP_INPUT_DEBUG
mbed714	0:d616ece2d859	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
mbed714	0:d616ece2d859	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
mbed714	0:d616ece2d859	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
mbed714	0:d616ece2d859	280	#endif /* TCP_INPUT_DEBUG */
mbed714	0:d616ece2d859	281
mbed714	0:d616ece2d859	282
mbed714	0:d616ece2d859	283	if (pcb != NULL) {
mbed714	0:d616ece2d859	284	/* The incoming segment belongs to a connection. */
mbed714	0:d616ece2d859	285	#if TCP_INPUT_DEBUG
mbed714	0:d616ece2d859	286	#if TCP_DEBUG
mbed714	0:d616ece2d859	287	tcp_debug_print_state(pcb->state);
mbed714	0:d616ece2d859	288	#endif /* TCP_DEBUG */
mbed714	0:d616ece2d859	289	#endif /* TCP_INPUT_DEBUG */
mbed714	0:d616ece2d859	290
mbed714	0:d616ece2d859	291	/* Set up a tcp_seg structure. */
mbed714	0:d616ece2d859	292	inseg.next = NULL;
mbed714	0:d616ece2d859	293	inseg.len = p->tot_len;
mbed714	0:d616ece2d859	294	inseg.dataptr = p->payload;
mbed714	0:d616ece2d859	295	inseg.p = p;
mbed714	0:d616ece2d859	296	inseg.tcphdr = tcphdr;
mbed714	0:d616ece2d859	297
mbed714	0:d616ece2d859	298	recv_data = NULL;
mbed714	0:d616ece2d859	299	recv_flags = 0;
mbed714	0:d616ece2d859	300
mbed714	0:d616ece2d859	301	/* If there is data which was previously "refused" by upper layer */
mbed714	0:d616ece2d859	302	if (pcb->refused_data != NULL) {
mbed714	0:d616ece2d859	303	/* Notify again application with data previously received. */
mbed714	0:d616ece2d859	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
mbed714	0:d616ece2d859	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
mbed714	0:d616ece2d859	306	if (err == ERR_OK) {
mbed714	0:d616ece2d859	307	pcb->refused_data = NULL;
mbed714	0:d616ece2d859	308	} else {
mbed714	0:d616ece2d859	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
mbed714	0:d616ece2d859	310	/* drop incoming packets, because pcb is "full" */
mbed714	0:d616ece2d859	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
mbed714	0:d616ece2d859	312	TCP_STATS_INC(tcp.drop);
mbed714	0:d616ece2d859	313	snmp_inc_tcpinerrs();
mbed714	0:d616ece2d859	314	pbuf_free(p);
mbed714	0:d616ece2d859	315	return;
mbed714	0:d616ece2d859	316	}
mbed714	0:d616ece2d859	317	}
mbed714	0:d616ece2d859	318	tcp_input_pcb = pcb;
mbed714	0:d616ece2d859	319	err = tcp_process(pcb);
mbed714	0:d616ece2d859	320	/* A return value of ERR_ABRT means that tcp_abort() was called
mbed714	0:d616ece2d859	321	and that the pcb has been freed. If so, we don't do anything. */
mbed714	0:d616ece2d859	322	if (err != ERR_ABRT) {
mbed714	0:d616ece2d859	323	if (recv_flags & TF_RESET) {
mbed714	0:d616ece2d859	324	/* TF_RESET means that the connection was reset by the other
mbed714	0:d616ece2d859	325	end. We then call the error callback to inform the
mbed714	0:d616ece2d859	326	application that the connection is dead before we
mbed714	0:d616ece2d859	327	deallocate the PCB. */
mbed714	0:d616ece2d859	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
mbed714	0:d616ece2d859	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
mbed714	0:d616ece2d859	330	memp_free(MEMP_TCP_PCB, pcb);
mbed714	0:d616ece2d859	331	} else if (recv_flags & TF_CLOSED) {
mbed714	0:d616ece2d859	332	/* The connection has been closed and we will deallocate the
mbed714	0:d616ece2d859	333	PCB. */
mbed714	0:d616ece2d859	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
mbed714	0:d616ece2d859	335	memp_free(MEMP_TCP_PCB, pcb);
mbed714	0:d616ece2d859	336	} else {
mbed714	0:d616ece2d859	337	err = ERR_OK;
mbed714	0:d616ece2d859	338	/* If the application has registered a "sent" function to be
mbed714	0:d616ece2d859	339	called when new send buffer space is available, we call it
mbed714	0:d616ece2d859	340	now. */
mbed714	0:d616ece2d859	341	if (pcb->acked > 0) {
mbed714	0:d616ece2d859	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
mbed714	0:d616ece2d859	343	if (err == ERR_ABRT) {
mbed714	0:d616ece2d859	344	goto aborted;
mbed714	0:d616ece2d859	345	}
mbed714	0:d616ece2d859	346	}
mbed714	0:d616ece2d859	347
mbed714	0:d616ece2d859	348	if (recv_data != NULL) {
mbed714	0:d616ece2d859	349	if (pcb->flags & TF_RXCLOSED) {
mbed714	0:d616ece2d859	350	/* received data although already closed -> abort (send RST) to
mbed714	0:d616ece2d859	351	notify the remote host that not all data has been processed */
mbed714	0:d616ece2d859	352	pbuf_free(recv_data);
mbed714	0:d616ece2d859	353	tcp_abort(pcb);
mbed714	0:d616ece2d859	354	goto aborted;
mbed714	0:d616ece2d859	355	}
mbed714	0:d616ece2d859	356	if (flags & TCP_PSH) {
mbed714	0:d616ece2d859	357	recv_data->flags \|= PBUF_FLAG_PUSH;
mbed714	0:d616ece2d859	358	}
mbed714	0:d616ece2d859	359
mbed714	0:d616ece2d859	360	/* Notify application that data has been received. */
mbed714	0:d616ece2d859	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
mbed714	0:d616ece2d859	362	if (err == ERR_ABRT) {
mbed714	0:d616ece2d859	363	goto aborted;
mbed714	0:d616ece2d859	364	}
mbed714	0:d616ece2d859	365
mbed714	0:d616ece2d859	366	/* If the upper layer can't receive this data, store it */
mbed714	0:d616ece2d859	367	if (err != ERR_OK) {
mbed714	0:d616ece2d859	368	pcb->refused_data = recv_data;
mbed714	0:d616ece2d859	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
mbed714	0:d616ece2d859	370	}
mbed714	0:d616ece2d859	371	}
mbed714	0:d616ece2d859	372
mbed714	0:d616ece2d859	373	/* If a FIN segment was received, we call the callback
mbed714	0:d616ece2d859	374	function with a NULL buffer to indicate EOF. */
mbed714	0:d616ece2d859	375	if (recv_flags & TF_GOT_FIN) {
mbed714	0:d616ece2d859	376	/* correct rcv_wnd as the application won't call tcp_recved()
mbed714	0:d616ece2d859	377	for the FIN's seqno */
mbed714	0:d616ece2d859	378	if (pcb->rcv_wnd != TCP_WND) {
mbed714	0:d616ece2d859	379	pcb->rcv_wnd++;
mbed714	0:d616ece2d859	380	}
mbed714	0:d616ece2d859	381	TCP_EVENT_CLOSED(pcb, err);
mbed714	0:d616ece2d859	382	if (err == ERR_ABRT) {
mbed714	0:d616ece2d859	383	goto aborted;
mbed714	0:d616ece2d859	384	}
mbed714	0:d616ece2d859	385	}
mbed714	0:d616ece2d859	386
mbed714	0:d616ece2d859	387	tcp_input_pcb = NULL;
mbed714	0:d616ece2d859	388	/* Try to send something out. */
mbed714	0:d616ece2d859	389	tcp_output(pcb);
mbed714	0:d616ece2d859	390	#if TCP_INPUT_DEBUG
mbed714	0:d616ece2d859	391	#if TCP_DEBUG
mbed714	0:d616ece2d859	392	tcp_debug_print_state(pcb->state);
mbed714	0:d616ece2d859	393	#endif /* TCP_DEBUG */
mbed714	0:d616ece2d859	394	#endif /* TCP_INPUT_DEBUG */
mbed714	0:d616ece2d859	395	}
mbed714	0:d616ece2d859	396	}
mbed714	0:d616ece2d859	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
mbed714	0:d616ece2d859	398	Below this line, 'pcb' may not be dereferenced! */
mbed714	0:d616ece2d859	399	aborted:
mbed714	0:d616ece2d859	400	tcp_input_pcb = NULL;
mbed714	0:d616ece2d859	401	recv_data = NULL;
mbed714	0:d616ece2d859	402
mbed714	0:d616ece2d859	403	/* give up our reference to inseg.p */
mbed714	0:d616ece2d859	404	if (inseg.p != NULL)
mbed714	0:d616ece2d859	405	{
mbed714	0:d616ece2d859	406	pbuf_free(inseg.p);
mbed714	0:d616ece2d859	407	inseg.p = NULL;
mbed714	0:d616ece2d859	408	}
mbed714	0:d616ece2d859	409	} else {
mbed714	0:d616ece2d859	410
mbed714	0:d616ece2d859	411	/* If no matching PCB was found, send a TCP RST (reset) to the
mbed714	0:d616ece2d859	412	sender. */
mbed714	0:d616ece2d859	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
mbed714	0:d616ece2d859	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
mbed714	0:d616ece2d859	415	TCP_STATS_INC(tcp.proterr);
mbed714	0:d616ece2d859	416	TCP_STATS_INC(tcp.drop);
mbed714	0:d616ece2d859	417	tcp_rst(ackno, seqno + tcplen,
mbed714	0:d616ece2d859	418	ip_current_dest_addr(), ip_current_src_addr(),
mbed714	0:d616ece2d859	419	tcphdr->dest, tcphdr->src);
mbed714	0:d616ece2d859	420	}
mbed714	0:d616ece2d859	421	pbuf_free(p);
mbed714	0:d616ece2d859	422	}
mbed714	0:d616ece2d859	423
mbed714	0:d616ece2d859	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
mbed714	0:d616ece2d859	425	PERF_STOP("tcp_input");
mbed714	0:d616ece2d859	426	}
mbed714	0:d616ece2d859	427
mbed714	0:d616ece2d859	428	/**
mbed714	0:d616ece2d859	429	* Called by tcp_input() when a segment arrives for a listening
mbed714	0:d616ece2d859	430	* connection (from tcp_input()).
mbed714	0:d616ece2d859	431	*
mbed714	0:d616ece2d859	432	* @param pcb the tcp_pcb_listen for which a segment arrived
mbed714	0:d616ece2d859	433	* @return ERR_OK if the segment was processed
mbed714	0:d616ece2d859	434	* another err_t on error
mbed714	0:d616ece2d859	435	*
mbed714	0:d616ece2d859	436	* @note the return value is not (yet?) used in tcp_input()
mbed714	0:d616ece2d859	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
mbed714	0:d616ece2d859	438	* involved is passed as a parameter to this function
mbed714	0:d616ece2d859	439	*/
mbed714	0:d616ece2d859	440	static err_t
mbed714	0:d616ece2d859	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
mbed714	0:d616ece2d859	442	{
mbed714	0:d616ece2d859	443	struct tcp_pcb *npcb;
mbed714	0:d616ece2d859	444	err_t rc;
mbed714	0:d616ece2d859	445
mbed714	0:d616ece2d859	446	/* In the LISTEN state, we check for incoming SYN segments,
mbed714	0:d616ece2d859	447	creates a new PCB, and responds with a SYN\|ACK. */
mbed714	0:d616ece2d859	448	if (flags & TCP_ACK) {
mbed714	0:d616ece2d859	449	/* For incoming segments with the ACK flag set, respond with a
mbed714	0:d616ece2d859	450	RST. */
mbed714	0:d616ece2d859	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
mbed714	0:d616ece2d859	452	tcp_rst(ackno + 1, seqno + tcplen,
mbed714	0:d616ece2d859	453	ip_current_dest_addr(), ip_current_src_addr(),
mbed714	0:d616ece2d859	454	tcphdr->dest, tcphdr->src);
mbed714	0:d616ece2d859	455	} else if (flags & TCP_SYN) {
mbed714	0:d616ece2d859	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
mbed714	0:d616ece2d859	457	#if TCP_LISTEN_BACKLOG
mbed714	0:d616ece2d859	458	if (pcb->accepts_pending >= pcb->backlog) {
mbed714	0:d616ece2d859	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
mbed714	0:d616ece2d859	460	return ERR_ABRT;
mbed714	0:d616ece2d859	461	}
mbed714	0:d616ece2d859	462	#endif /* TCP_LISTEN_BACKLOG */
mbed714	0:d616ece2d859	463	npcb = tcp_alloc(pcb->prio);
mbed714	0:d616ece2d859	464	/* If a new PCB could not be created (probably due to lack of memory),
mbed714	0:d616ece2d859	465	we don't do anything, but rely on the sender will retransmit the
mbed714	0:d616ece2d859	466	SYN at a time when we have more memory available. */
mbed714	0:d616ece2d859	467	if (npcb == NULL) {
mbed714	0:d616ece2d859	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
mbed714	0:d616ece2d859	469	TCP_STATS_INC(tcp.memerr);
mbed714	0:d616ece2d859	470	return ERR_MEM;
mbed714	0:d616ece2d859	471	}
mbed714	0:d616ece2d859	472	#if TCP_LISTEN_BACKLOG
mbed714	0:d616ece2d859	473	pcb->accepts_pending++;
mbed714	0:d616ece2d859	474	#endif /* TCP_LISTEN_BACKLOG */
mbed714	0:d616ece2d859	475	/* Set up the new PCB. */
mbed714	0:d616ece2d859	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
mbed714	0:d616ece2d859	477	npcb->local_port = pcb->local_port;
mbed714	0:d616ece2d859	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
mbed714	0:d616ece2d859	479	npcb->remote_port = tcphdr->src;
mbed714	0:d616ece2d859	480	npcb->state = SYN_RCVD;
mbed714	0:d616ece2d859	481	npcb->rcv_nxt = seqno + 1;
mbed714	0:d616ece2d859	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
mbed714	0:d616ece2d859	483	npcb->snd_wnd = tcphdr->wnd;
mbed714	0:d616ece2d859	484	npcb->ssthresh = npcb->snd_wnd;
mbed714	0:d616ece2d859	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
mbed714	0:d616ece2d859	486	npcb->callback_arg = pcb->callback_arg;
mbed714	0:d616ece2d859	487	#if LWIP_CALLBACK_API
mbed714	0:d616ece2d859	488	npcb->accept = pcb->accept;
mbed714	0:d616ece2d859	489	#endif /* LWIP_CALLBACK_API */
mbed714	0:d616ece2d859	490	/* inherit socket options */
mbed714	0:d616ece2d859	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
mbed714	0:d616ece2d859	492	/* Register the new PCB so that we can begin receiving segments
mbed714	0:d616ece2d859	493	for it. */
mbed714	0:d616ece2d859	494	TCP_REG(&tcp_active_pcbs, npcb);
mbed714	0:d616ece2d859	495
mbed714	0:d616ece2d859	496	/* Parse any options in the SYN. */
mbed714	0:d616ece2d859	497	tcp_parseopt(npcb);
mbed714	0:d616ece2d859	498	#if TCP_CALCULATE_EFF_SEND_MSS
mbed714	0:d616ece2d859	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
mbed714	0:d616ece2d859	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
mbed714	0:d616ece2d859	501
mbed714	0:d616ece2d859	502	snmp_inc_tcppassiveopens();
mbed714	0:d616ece2d859	503
mbed714	0:d616ece2d859	504	/* Send a SYN\|ACK together with the MSS option. */
mbed714	0:d616ece2d859	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
mbed714	0:d616ece2d859	506	if (rc != ERR_OK) {
mbed714	0:d616ece2d859	507	tcp_abandon(npcb, 0);
mbed714	0:d616ece2d859	508	return rc;
mbed714	0:d616ece2d859	509	}
mbed714	0:d616ece2d859	510	return tcp_output(npcb);
mbed714	0:d616ece2d859	511	}
mbed714	0:d616ece2d859	512	return ERR_OK;
mbed714	0:d616ece2d859	513	}
mbed714	0:d616ece2d859	514
mbed714	0:d616ece2d859	515	/**
mbed714	0:d616ece2d859	516	* Called by tcp_input() when a segment arrives for a connection in
mbed714	0:d616ece2d859	517	* TIME_WAIT.
mbed714	0:d616ece2d859	518	*
mbed714	0:d616ece2d859	519	* @param pcb the tcp_pcb for which a segment arrived
mbed714	0:d616ece2d859	520	*
mbed714	0:d616ece2d859	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
mbed714	0:d616ece2d859	522	* involved is passed as a parameter to this function
mbed714	0:d616ece2d859	523	*/
mbed714	0:d616ece2d859	524	static err_t
mbed714	0:d616ece2d859	525	tcp_timewait_input(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	526	{
mbed714	0:d616ece2d859	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
mbed714	0:d616ece2d859	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
mbed714	0:d616ece2d859	529	* - first check sequence number - we skip that one in TIME_WAIT (always
mbed714	0:d616ece2d859	530	* acceptable since we only send ACKs)
mbed714	0:d616ece2d859	531	* - second check the RST bit (... return) */
mbed714	0:d616ece2d859	532	if (flags & TCP_RST) {
mbed714	0:d616ece2d859	533	return ERR_OK;
mbed714	0:d616ece2d859	534	}
mbed714	0:d616ece2d859	535	/* - fourth, check the SYN bit, */
mbed714	0:d616ece2d859	536	if (flags & TCP_SYN) {
mbed714	0:d616ece2d859	537	/* If an incoming segment is not acceptable, an acknowledgment
mbed714	0:d616ece2d859	538	should be sent in reply */
mbed714	0:d616ece2d859	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
mbed714	0:d616ece2d859	540	/* If the SYN is in the window it is an error, send a reset */
mbed714	0:d616ece2d859	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
mbed714	0:d616ece2d859	542	tcphdr->dest, tcphdr->src);
mbed714	0:d616ece2d859	543	return ERR_OK;
mbed714	0:d616ece2d859	544	}
mbed714	0:d616ece2d859	545	} else if (flags & TCP_FIN) {
mbed714	0:d616ece2d859	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
mbed714	0:d616ece2d859	547	Restart the 2 MSL time-wait timeout.*/
mbed714	0:d616ece2d859	548	pcb->tmr = tcp_ticks;
mbed714	0:d616ece2d859	549	}
mbed714	0:d616ece2d859	550
mbed714	0:d616ece2d859	551	if ((tcplen > 0)) {
mbed714	0:d616ece2d859	552	/* Acknowledge data, FIN or out-of-window SYN */
mbed714	0:d616ece2d859	553	pcb->flags \|= TF_ACK_NOW;
mbed714	0:d616ece2d859	554	return tcp_output(pcb);
mbed714	0:d616ece2d859	555	}
mbed714	0:d616ece2d859	556	return ERR_OK;
mbed714	0:d616ece2d859	557	}
mbed714	0:d616ece2d859	558
mbed714	0:d616ece2d859	559	/**
mbed714	0:d616ece2d859	560	* Implements the TCP state machine. Called by tcp_input. In some
mbed714	0:d616ece2d859	561	* states tcp_receive() is called to receive data. The tcp_seg
mbed714	0:d616ece2d859	562	* argument will be freed by the caller (tcp_input()) unless the
mbed714	0:d616ece2d859	563	* recv_data pointer in the pcb is set.
mbed714	0:d616ece2d859	564	*
mbed714	0:d616ece2d859	565	* @param pcb the tcp_pcb for which a segment arrived
mbed714	0:d616ece2d859	566	*
mbed714	0:d616ece2d859	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
mbed714	0:d616ece2d859	568	* involved is passed as a parameter to this function
mbed714	0:d616ece2d859	569	*/
mbed714	0:d616ece2d859	570	static err_t
mbed714	0:d616ece2d859	571	tcp_process(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	572	{
mbed714	0:d616ece2d859	573	struct tcp_seg *rseg;
mbed714	0:d616ece2d859	574	u8_t acceptable = 0;
mbed714	0:d616ece2d859	575	err_t err;
mbed714	0:d616ece2d859	576
mbed714	0:d616ece2d859	577	err = ERR_OK;
mbed714	0:d616ece2d859	578
mbed714	0:d616ece2d859	579	/* Process incoming RST segments. */
mbed714	0:d616ece2d859	580	if (flags & TCP_RST) {
mbed714	0:d616ece2d859	581	/* First, determine if the reset is acceptable. */
mbed714	0:d616ece2d859	582	if (pcb->state == SYN_SENT) {
mbed714	0:d616ece2d859	583	if (ackno == pcb->snd_nxt) {
mbed714	0:d616ece2d859	584	acceptable = 1;
mbed714	0:d616ece2d859	585	}
mbed714	0:d616ece2d859	586	} else {
mbed714	0:d616ece2d859	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
mbed714	0:d616ece2d859	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
mbed714	0:d616ece2d859	589	acceptable = 1;
mbed714	0:d616ece2d859	590	}
mbed714	0:d616ece2d859	591	}
mbed714	0:d616ece2d859	592
mbed714	0:d616ece2d859	593	if (acceptable) {
mbed714	0:d616ece2d859	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
mbed714	0:d616ece2d859	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
mbed714	0:d616ece2d859	596	recv_flags \|= TF_RESET;
mbed714	0:d616ece2d859	597	pcb->flags &= ~TF_ACK_DELAY;
mbed714	0:d616ece2d859	598	return ERR_RST;
mbed714	0:d616ece2d859	599	} else {
mbed714	0:d616ece2d859	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
mbed714	0:d616ece2d859	601	seqno, pcb->rcv_nxt));
mbed714	0:d616ece2d859	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
mbed714	0:d616ece2d859	603	seqno, pcb->rcv_nxt));
mbed714	0:d616ece2d859	604	return ERR_OK;
mbed714	0:d616ece2d859	605	}
mbed714	0:d616ece2d859	606	}
mbed714	0:d616ece2d859	607
mbed714	0:d616ece2d859	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
mbed714	0:d616ece2d859	609	/* Cope with new connection attempt after remote end crashed */
mbed714	0:d616ece2d859	610	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	611	return ERR_OK;
mbed714	0:d616ece2d859	612	}
mbed714	0:d616ece2d859	613
mbed714	0:d616ece2d859	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
mbed714	0:d616ece2d859	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
mbed714	0:d616ece2d859	616	pcb->tmr = tcp_ticks;
mbed714	0:d616ece2d859	617	}
mbed714	0:d616ece2d859	618	pcb->keep_cnt_sent = 0;
mbed714	0:d616ece2d859	619
mbed714	0:d616ece2d859	620	tcp_parseopt(pcb);
mbed714	0:d616ece2d859	621
mbed714	0:d616ece2d859	622	/* Do different things depending on the TCP state. */
mbed714	0:d616ece2d859	623	switch (pcb->state) {
mbed714	0:d616ece2d859	624	case SYN_SENT:
mbed714	0:d616ece2d859	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
mbed714	0:d616ece2d859	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
mbed714	0:d616ece2d859	627	/* received SYN ACK with expected sequence number? */
mbed714	0:d616ece2d859	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
mbed714	0:d616ece2d859	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
mbed714	0:d616ece2d859	630	pcb->snd_buf++;
mbed714	0:d616ece2d859	631	pcb->rcv_nxt = seqno + 1;
mbed714	0:d616ece2d859	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
mbed714	0:d616ece2d859	633	pcb->lastack = ackno;
mbed714	0:d616ece2d859	634	pcb->snd_wnd = tcphdr->wnd;
mbed714	0:d616ece2d859	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
mbed714	0:d616ece2d859	636	pcb->state = ESTABLISHED;
mbed714	0:d616ece2d859	637
mbed714	0:d616ece2d859	638	#if TCP_CALCULATE_EFF_SEND_MSS
mbed714	0:d616ece2d859	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
mbed714	0:d616ece2d859	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
mbed714	0:d616ece2d859	641
mbed714	0:d616ece2d859	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
mbed714	0:d616ece2d859	643	* but for the default value of pcb->mss) */
mbed714	0:d616ece2d859	644	pcb->ssthresh = pcb->mss * 10;
mbed714	0:d616ece2d859	645
mbed714	0:d616ece2d859	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
mbed714	0:d616ece2d859	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
mbed714	0:d616ece2d859	648	--pcb->snd_queuelen;
mbed714	0:d616ece2d859	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	650	rseg = pcb->unacked;
mbed714	0:d616ece2d859	651	pcb->unacked = rseg->next;
mbed714	0:d616ece2d859	652
mbed714	0:d616ece2d859	653	/* If there's nothing left to acknowledge, stop the retransmit
mbed714	0:d616ece2d859	654	timer, otherwise reset it to start again */
mbed714	0:d616ece2d859	655	if(pcb->unacked == NULL)
mbed714	0:d616ece2d859	656	pcb->rtime = -1;
mbed714	0:d616ece2d859	657	else {
mbed714	0:d616ece2d859	658	pcb->rtime = 0;
mbed714	0:d616ece2d859	659	pcb->nrtx = 0;
mbed714	0:d616ece2d859	660	}
mbed714	0:d616ece2d859	661
mbed714	0:d616ece2d859	662	tcp_seg_free(rseg);
mbed714	0:d616ece2d859	663
mbed714	0:d616ece2d859	664	/* Call the user specified function to call when sucessfully
mbed714	0:d616ece2d859	665	* connected. */
mbed714	0:d616ece2d859	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
mbed714	0:d616ece2d859	667	if (err == ERR_ABRT) {
mbed714	0:d616ece2d859	668	return ERR_ABRT;
mbed714	0:d616ece2d859	669	}
mbed714	0:d616ece2d859	670	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	671	}
mbed714	0:d616ece2d859	672	/* received ACK? possibly a half-open connection */
mbed714	0:d616ece2d859	673	else if (flags & TCP_ACK) {
mbed714	0:d616ece2d859	674	/* send a RST to bring the other side in a non-synchronized state. */
mbed714	0:d616ece2d859	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
mbed714	0:d616ece2d859	676	tcphdr->dest, tcphdr->src);
mbed714	0:d616ece2d859	677	}
mbed714	0:d616ece2d859	678	break;
mbed714	0:d616ece2d859	679	case SYN_RCVD:
mbed714	0:d616ece2d859	680	if (flags & TCP_ACK) {
mbed714	0:d616ece2d859	681	/* expected ACK number? */
mbed714	0:d616ece2d859	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
mbed714	0:d616ece2d859	683	u16_t old_cwnd;
mbed714	0:d616ece2d859	684	pcb->state = ESTABLISHED;
mbed714	0:d616ece2d859	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed714	0:d616ece2d859	686	#if LWIP_CALLBACK_API
mbed714	0:d616ece2d859	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
mbed714	0:d616ece2d859	688	#endif
mbed714	0:d616ece2d859	689	/* Call the accept function. */
mbed714	0:d616ece2d859	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
mbed714	0:d616ece2d859	691	if (err != ERR_OK) {
mbed714	0:d616ece2d859	692	/* If the accept function returns with an error, we abort
mbed714	0:d616ece2d859	693	* the connection. */
mbed714	0:d616ece2d859	694	/* Already aborted? */
mbed714	0:d616ece2d859	695	if (err != ERR_ABRT) {
mbed714	0:d616ece2d859	696	tcp_abort(pcb);
mbed714	0:d616ece2d859	697	}
mbed714	0:d616ece2d859	698	return ERR_ABRT;
mbed714	0:d616ece2d859	699	}
mbed714	0:d616ece2d859	700	old_cwnd = pcb->cwnd;
mbed714	0:d616ece2d859	701	/* If there was any data contained within this ACK,
mbed714	0:d616ece2d859	702	* we'd better pass it on to the application as well. */
mbed714	0:d616ece2d859	703	tcp_receive(pcb);
mbed714	0:d616ece2d859	704
mbed714	0:d616ece2d859	705	/* Prevent ACK for SYN to generate a sent event */
mbed714	0:d616ece2d859	706	if (pcb->acked != 0) {
mbed714	0:d616ece2d859	707	pcb->acked--;
mbed714	0:d616ece2d859	708	}
mbed714	0:d616ece2d859	709
mbed714	0:d616ece2d859	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
mbed714	0:d616ece2d859	711
mbed714	0:d616ece2d859	712	if (recv_flags & TF_GOT_FIN) {
mbed714	0:d616ece2d859	713	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	714	pcb->state = CLOSE_WAIT;
mbed714	0:d616ece2d859	715	}
mbed714	0:d616ece2d859	716	} else {
mbed714	0:d616ece2d859	717	/* incorrect ACK number, send RST */
mbed714	0:d616ece2d859	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
mbed714	0:d616ece2d859	719	tcphdr->dest, tcphdr->src);
mbed714	0:d616ece2d859	720	}
mbed714	0:d616ece2d859	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
mbed714	0:d616ece2d859	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
mbed714	0:d616ece2d859	723	tcp_rexmit(pcb);
mbed714	0:d616ece2d859	724	}
mbed714	0:d616ece2d859	725	break;
mbed714	0:d616ece2d859	726	case CLOSE_WAIT:
mbed714	0:d616ece2d859	727	/* FALLTHROUGH */
mbed714	0:d616ece2d859	728	case ESTABLISHED:
mbed714	0:d616ece2d859	729	tcp_receive(pcb);
mbed714	0:d616ece2d859	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
mbed714	0:d616ece2d859	731	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	732	pcb->state = CLOSE_WAIT;
mbed714	0:d616ece2d859	733	}
mbed714	0:d616ece2d859	734	break;
mbed714	0:d616ece2d859	735	case FIN_WAIT_1:
mbed714	0:d616ece2d859	736	tcp_receive(pcb);
mbed714	0:d616ece2d859	737	if (recv_flags & TF_GOT_FIN) {
mbed714	0:d616ece2d859	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
mbed714	0:d616ece2d859	739	LWIP_DEBUGF(TCP_DEBUG,
mbed714	0:d616ece2d859	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed714	0:d616ece2d859	741	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	742	tcp_pcb_purge(pcb);
mbed714	0:d616ece2d859	743	TCP_RMV(&tcp_active_pcbs, pcb);
mbed714	0:d616ece2d859	744	pcb->state = TIME_WAIT;
mbed714	0:d616ece2d859	745	TCP_REG(&tcp_tw_pcbs, pcb);
mbed714	0:d616ece2d859	746	} else {
mbed714	0:d616ece2d859	747	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	748	pcb->state = CLOSING;
mbed714	0:d616ece2d859	749	}
mbed714	0:d616ece2d859	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
mbed714	0:d616ece2d859	751	pcb->state = FIN_WAIT_2;
mbed714	0:d616ece2d859	752	}
mbed714	0:d616ece2d859	753	break;
mbed714	0:d616ece2d859	754	case FIN_WAIT_2:
mbed714	0:d616ece2d859	755	tcp_receive(pcb);
mbed714	0:d616ece2d859	756	if (recv_flags & TF_GOT_FIN) {
mbed714	0:d616ece2d859	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed714	0:d616ece2d859	758	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	759	tcp_pcb_purge(pcb);
mbed714	0:d616ece2d859	760	TCP_RMV(&tcp_active_pcbs, pcb);
mbed714	0:d616ece2d859	761	pcb->state = TIME_WAIT;
mbed714	0:d616ece2d859	762	TCP_REG(&tcp_tw_pcbs, pcb);
mbed714	0:d616ece2d859	763	}
mbed714	0:d616ece2d859	764	break;
mbed714	0:d616ece2d859	765	case CLOSING:
mbed714	0:d616ece2d859	766	tcp_receive(pcb);
mbed714	0:d616ece2d859	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
mbed714	0:d616ece2d859	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed714	0:d616ece2d859	769	tcp_pcb_purge(pcb);
mbed714	0:d616ece2d859	770	TCP_RMV(&tcp_active_pcbs, pcb);
mbed714	0:d616ece2d859	771	pcb->state = TIME_WAIT;
mbed714	0:d616ece2d859	772	TCP_REG(&tcp_tw_pcbs, pcb);
mbed714	0:d616ece2d859	773	}
mbed714	0:d616ece2d859	774	break;
mbed714	0:d616ece2d859	775	case LAST_ACK:
mbed714	0:d616ece2d859	776	tcp_receive(pcb);
mbed714	0:d616ece2d859	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
mbed714	0:d616ece2d859	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed714	0:d616ece2d859	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
mbed714	0:d616ece2d859	780	recv_flags \|= TF_CLOSED;
mbed714	0:d616ece2d859	781	}
mbed714	0:d616ece2d859	782	break;
mbed714	0:d616ece2d859	783	default:
mbed714	0:d616ece2d859	784	break;
mbed714	0:d616ece2d859	785	}
mbed714	0:d616ece2d859	786	return ERR_OK;
mbed714	0:d616ece2d859	787	}
mbed714	0:d616ece2d859	788
mbed714	0:d616ece2d859	789	#if TCP_QUEUE_OOSEQ
mbed714	0:d616ece2d859	790	/**
mbed714	0:d616ece2d859	791	* Insert segment into the list (segments covered with new one will be deleted)
mbed714	0:d616ece2d859	792	*
mbed714	0:d616ece2d859	793	* Called from tcp_receive()
mbed714	0:d616ece2d859	794	*/
mbed714	0:d616ece2d859	795	static void
mbed714	0:d616ece2d859	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
mbed714	0:d616ece2d859	797	{
mbed714	0:d616ece2d859	798	struct tcp_seg *old_seg;
mbed714	0:d616ece2d859	799
mbed714	0:d616ece2d859	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	801	/* received segment overlaps all following segments */
mbed714	0:d616ece2d859	802	tcp_segs_free(next);
mbed714	0:d616ece2d859	803	next = NULL;
mbed714	0:d616ece2d859	804	}
mbed714	0:d616ece2d859	805	else {
mbed714	0:d616ece2d859	806	/* delete some following segments
mbed714	0:d616ece2d859	807	oos queue may have segments with FIN flag */
mbed714	0:d616ece2d859	808	while (next &&
mbed714	0:d616ece2d859	809	TCP_SEQ_GEQ((seqno + cseg->len),
mbed714	0:d616ece2d859	810	(next->tcphdr->seqno + next->len))) {
mbed714	0:d616ece2d859	811	/* cseg with FIN already processed */
mbed714	0:d616ece2d859	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
mbed714	0:d616ece2d859	814	}
mbed714	0:d616ece2d859	815	old_seg = next;
mbed714	0:d616ece2d859	816	next = next->next;
mbed714	0:d616ece2d859	817	tcp_seg_free(old_seg);
mbed714	0:d616ece2d859	818	}
mbed714	0:d616ece2d859	819	if (next &&
mbed714	0:d616ece2d859	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
mbed714	0:d616ece2d859	821	/* We need to trim the incoming segment. */
mbed714	0:d616ece2d859	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
mbed714	0:d616ece2d859	823	pbuf_realloc(cseg->p, cseg->len);
mbed714	0:d616ece2d859	824	}
mbed714	0:d616ece2d859	825	}
mbed714	0:d616ece2d859	826	cseg->next = next;
mbed714	0:d616ece2d859	827	}
mbed714	0:d616ece2d859	828	#endif /* TCP_QUEUE_OOSEQ */
mbed714	0:d616ece2d859	829
mbed714	0:d616ece2d859	830	/**
mbed714	0:d616ece2d859	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
mbed714	0:d616ece2d859	832	* data, and if so frees the memory of the buffered data. Next, is places the
mbed714	0:d616ece2d859	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
mbed714	0:d616ece2d859	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
mbed714	0:d616ece2d859	835	* i it has been removed from the buffer.
mbed714	0:d616ece2d859	836	*
mbed714	0:d616ece2d859	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
mbed714	0:d616ece2d859	838	* estimation, the RTT is estimated here as well.
mbed714	0:d616ece2d859	839	*
mbed714	0:d616ece2d859	840	* Called from tcp_process().
mbed714	0:d616ece2d859	841	*/
mbed714	0:d616ece2d859	842	static void
mbed714	0:d616ece2d859	843	tcp_receive(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	844	{
mbed714	0:d616ece2d859	845	struct tcp_seg *next;
mbed714	0:d616ece2d859	846	#if TCP_QUEUE_OOSEQ
mbed714	0:d616ece2d859	847	struct tcp_seg prev, cseg;
mbed714	0:d616ece2d859	848	#endif /* TCP_QUEUE_OOSEQ */
mbed714	0:d616ece2d859	849	struct pbuf *p;
mbed714	0:d616ece2d859	850	s32_t off;
mbed714	0:d616ece2d859	851	s16_t m;
mbed714	0:d616ece2d859	852	u32_t right_wnd_edge;
mbed714	0:d616ece2d859	853	u16_t new_tot_len;
mbed714	0:d616ece2d859	854	int found_dupack = 0;
mbed714	0:d616ece2d859	855
mbed714	0:d616ece2d859	856	if (flags & TCP_ACK) {
mbed714	0:d616ece2d859	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
mbed714	0:d616ece2d859	858
mbed714	0:d616ece2d859	859	/* Update window. */
mbed714	0:d616ece2d859	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
mbed714	0:d616ece2d859	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
mbed714	0:d616ece2d859	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
mbed714	0:d616ece2d859	863	pcb->snd_wnd = tcphdr->wnd;
mbed714	0:d616ece2d859	864	pcb->snd_wl1 = seqno;
mbed714	0:d616ece2d859	865	pcb->snd_wl2 = ackno;
mbed714	0:d616ece2d859	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
mbed714	0:d616ece2d859	867	pcb->persist_backoff = 0;
mbed714	0:d616ece2d859	868	}
mbed714	0:d616ece2d859	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
mbed714	0:d616ece2d859	870	#if TCP_WND_DEBUG
mbed714	0:d616ece2d859	871	} else {
mbed714	0:d616ece2d859	872	if (pcb->snd_wnd != tcphdr->wnd) {
mbed714	0:d616ece2d859	873	LWIP_DEBUGF(TCP_WND_DEBUG,
mbed714	0:d616ece2d859	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
mbed714	0:d616ece2d859	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
mbed714	0:d616ece2d859	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
mbed714	0:d616ece2d859	877	}
mbed714	0:d616ece2d859	878	#endif /* TCP_WND_DEBUG */
mbed714	0:d616ece2d859	879	}
mbed714	0:d616ece2d859	880
mbed714	0:d616ece2d859	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
mbed714	0:d616ece2d859	882	* duplicate ack if:
mbed714	0:d616ece2d859	883	* 1) It doesn't ACK new data
mbed714	0:d616ece2d859	884	* 2) length of received packet is zero (i.e. no payload)
mbed714	0:d616ece2d859	885	* 3) the advertised window hasn't changed
mbed714	0:d616ece2d859	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
mbed714	0:d616ece2d859	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
mbed714	0:d616ece2d859	888	*
mbed714	0:d616ece2d859	889	* If it passes all five, should process as a dupack:
mbed714	0:d616ece2d859	890	* a) dupacks < 3: do nothing
mbed714	0:d616ece2d859	891	* b) dupacks == 3: fast retransmit
mbed714	0:d616ece2d859	892	* c) dupacks > 3: increase cwnd
mbed714	0:d616ece2d859	893	*
mbed714	0:d616ece2d859	894	* If it only passes 1-3, should reset dupack counter (and add to
mbed714	0:d616ece2d859	895	* stats, which we don't do in lwIP)
mbed714	0:d616ece2d859	896	*
mbed714	0:d616ece2d859	897	* If it only passes 1, should reset dupack counter
mbed714	0:d616ece2d859	898	*
mbed714	0:d616ece2d859	899	*/
mbed714	0:d616ece2d859	900
mbed714	0:d616ece2d859	901	/* Clause 1 */
mbed714	0:d616ece2d859	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
mbed714	0:d616ece2d859	903	pcb->acked = 0;
mbed714	0:d616ece2d859	904	/* Clause 2 */
mbed714	0:d616ece2d859	905	if (tcplen == 0) {
mbed714	0:d616ece2d859	906	/* Clause 3 */
mbed714	0:d616ece2d859	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
mbed714	0:d616ece2d859	908	/* Clause 4 */
mbed714	0:d616ece2d859	909	if (pcb->rtime >= 0) {
mbed714	0:d616ece2d859	910	/* Clause 5 */
mbed714	0:d616ece2d859	911	if (pcb->lastack == ackno) {
mbed714	0:d616ece2d859	912	found_dupack = 1;
mbed714	0:d616ece2d859	913	if (pcb->dupacks + 1 > pcb->dupacks)
mbed714	0:d616ece2d859	914	++pcb->dupacks;
mbed714	0:d616ece2d859	915	if (pcb->dupacks > 3) {
mbed714	0:d616ece2d859	916	/* Inflate the congestion window, but not if it means that
mbed714	0:d616ece2d859	917	the value overflows. */
mbed714	0:d616ece2d859	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
mbed714	0:d616ece2d859	919	pcb->cwnd += pcb->mss;
mbed714	0:d616ece2d859	920	}
mbed714	0:d616ece2d859	921	} else if (pcb->dupacks == 3) {
mbed714	0:d616ece2d859	922	/* Do fast retransmit */
mbed714	0:d616ece2d859	923	tcp_rexmit_fast(pcb);
mbed714	0:d616ece2d859	924	}
mbed714	0:d616ece2d859	925	}
mbed714	0:d616ece2d859	926	}
mbed714	0:d616ece2d859	927	}
mbed714	0:d616ece2d859	928	}
mbed714	0:d616ece2d859	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
mbed714	0:d616ece2d859	930	* count of consecutive duplicate acks */
mbed714	0:d616ece2d859	931	if (!found_dupack) {
mbed714	0:d616ece2d859	932	pcb->dupacks = 0;
mbed714	0:d616ece2d859	933	}
mbed714	0:d616ece2d859	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
mbed714	0:d616ece2d859	935	/* We come here when the ACK acknowledges new data. */
mbed714	0:d616ece2d859	936
mbed714	0:d616ece2d859	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
mbed714	0:d616ece2d859	938	in fast retransmit. Also reset the congestion window to the
mbed714	0:d616ece2d859	939	slow start threshold. */
mbed714	0:d616ece2d859	940	if (pcb->flags & TF_INFR) {
mbed714	0:d616ece2d859	941	pcb->flags &= ~TF_INFR;
mbed714	0:d616ece2d859	942	pcb->cwnd = pcb->ssthresh;
mbed714	0:d616ece2d859	943	}
mbed714	0:d616ece2d859	944
mbed714	0:d616ece2d859	945	/* Reset the number of retransmissions. */
mbed714	0:d616ece2d859	946	pcb->nrtx = 0;
mbed714	0:d616ece2d859	947
mbed714	0:d616ece2d859	948	/* Reset the retransmission time-out. */
mbed714	0:d616ece2d859	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
mbed714	0:d616ece2d859	950
mbed714	0:d616ece2d859	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
mbed714	0:d616ece2d859	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
mbed714	0:d616ece2d859	953
mbed714	0:d616ece2d859	954	pcb->snd_buf += pcb->acked;
mbed714	0:d616ece2d859	955
mbed714	0:d616ece2d859	956	/* Reset the fast retransmit variables. */
mbed714	0:d616ece2d859	957	pcb->dupacks = 0;
mbed714	0:d616ece2d859	958	pcb->lastack = ackno;
mbed714	0:d616ece2d859	959
mbed714	0:d616ece2d859	960	/* Update the congestion control variables (cwnd and
mbed714	0:d616ece2d859	961	ssthresh). */
mbed714	0:d616ece2d859	962	if (pcb->state >= ESTABLISHED) {
mbed714	0:d616ece2d859	963	if (pcb->cwnd < pcb->ssthresh) {
mbed714	0:d616ece2d859	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
mbed714	0:d616ece2d859	965	pcb->cwnd += pcb->mss;
mbed714	0:d616ece2d859	966	}
mbed714	0:d616ece2d859	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
mbed714	0:d616ece2d859	968	} else {
mbed714	0:d616ece2d859	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
mbed714	0:d616ece2d859	970	if (new_cwnd > pcb->cwnd) {
mbed714	0:d616ece2d859	971	pcb->cwnd = new_cwnd;
mbed714	0:d616ece2d859	972	}
mbed714	0:d616ece2d859	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
mbed714	0:d616ece2d859	974	}
mbed714	0:d616ece2d859	975	}
mbed714	0:d616ece2d859	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
mbed714	0:d616ece2d859	977	ackno,
mbed714	0:d616ece2d859	978	pcb->unacked != NULL?
mbed714	0:d616ece2d859	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
mbed714	0:d616ece2d859	980	pcb->unacked != NULL?
mbed714	0:d616ece2d859	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
mbed714	0:d616ece2d859	982
mbed714	0:d616ece2d859	983	/* Remove segment from the unacknowledged list if the incoming
mbed714	0:d616ece2d859	984	ACK acknowlegdes them. */
mbed714	0:d616ece2d859	985	while (pcb->unacked != NULL &&
mbed714	0:d616ece2d859	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
mbed714	0:d616ece2d859	987	TCP_TCPLEN(pcb->unacked), ackno)) {
mbed714	0:d616ece2d859	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
mbed714	0:d616ece2d859	989	ntohl(pcb->unacked->tcphdr->seqno),
mbed714	0:d616ece2d859	990	ntohl(pcb->unacked->tcphdr->seqno) +
mbed714	0:d616ece2d859	991	TCP_TCPLEN(pcb->unacked)));
mbed714	0:d616ece2d859	992
mbed714	0:d616ece2d859	993	next = pcb->unacked;
mbed714	0:d616ece2d859	994	pcb->unacked = pcb->unacked->next;
mbed714	0:d616ece2d859	995
mbed714	0:d616ece2d859	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
mbed714	0:d616ece2d859	998	/* Prevent ACK for FIN to generate a sent event */
mbed714	0:d616ece2d859	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
mbed714	0:d616ece2d859	1000	pcb->acked--;
mbed714	0:d616ece2d859	1001	}
mbed714	0:d616ece2d859	1002
mbed714	0:d616ece2d859	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
mbed714	0:d616ece2d859	1004	tcp_seg_free(next);
mbed714	0:d616ece2d859	1005
mbed714	0:d616ece2d859	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	1007	if (pcb->snd_queuelen != 0) {
mbed714	0:d616ece2d859	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
mbed714	0:d616ece2d859	1009	pcb->unsent != NULL);
mbed714	0:d616ece2d859	1010	}
mbed714	0:d616ece2d859	1011	}
mbed714	0:d616ece2d859	1012
mbed714	0:d616ece2d859	1013	/* If there's nothing left to acknowledge, stop the retransmit
mbed714	0:d616ece2d859	1014	timer, otherwise reset it to start again */
mbed714	0:d616ece2d859	1015	if(pcb->unacked == NULL)
mbed714	0:d616ece2d859	1016	pcb->rtime = -1;
mbed714	0:d616ece2d859	1017	else
mbed714	0:d616ece2d859	1018	pcb->rtime = 0;
mbed714	0:d616ece2d859	1019
mbed714	0:d616ece2d859	1020	pcb->polltmr = 0;
mbed714	0:d616ece2d859	1021	} else {
mbed714	0:d616ece2d859	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
mbed714	0:d616ece2d859	1023	pcb->acked = 0;
mbed714	0:d616ece2d859	1024	}
mbed714	0:d616ece2d859	1025
mbed714	0:d616ece2d859	1026	/* We go through the ->unsent list to see if any of the segments
mbed714	0:d616ece2d859	1027	on the list are acknowledged by the ACK. This may seem
mbed714	0:d616ece2d859	1028	strange since an "unsent" segment shouldn't be acked. The
mbed714	0:d616ece2d859	1029	rationale is that lwIP puts all outstanding segments on the
mbed714	0:d616ece2d859	1030	->unsent list after a retransmission, so these segments may
mbed714	0:d616ece2d859	1031	in fact have been sent once. */
mbed714	0:d616ece2d859	1032	while (pcb->unsent != NULL &&
mbed714	0:d616ece2d859	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
mbed714	0:d616ece2d859	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
mbed714	0:d616ece2d859	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
mbed714	0:d616ece2d859	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
mbed714	0:d616ece2d859	1037	TCP_TCPLEN(pcb->unsent)));
mbed714	0:d616ece2d859	1038
mbed714	0:d616ece2d859	1039	next = pcb->unsent;
mbed714	0:d616ece2d859	1040	pcb->unsent = pcb->unsent->next;
mbed714	0:d616ece2d859	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
mbed714	0:d616ece2d859	1043	/* Prevent ACK for FIN to generate a sent event */
mbed714	0:d616ece2d859	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
mbed714	0:d616ece2d859	1045	pcb->acked--;
mbed714	0:d616ece2d859	1046	}
mbed714	0:d616ece2d859	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
mbed714	0:d616ece2d859	1048	tcp_seg_free(next);
mbed714	0:d616ece2d859	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
mbed714	0:d616ece2d859	1050	if (pcb->snd_queuelen != 0) {
mbed714	0:d616ece2d859	1051	LWIP_ASSERT("tcp_receive: valid queue length",
mbed714	0:d616ece2d859	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
mbed714	0:d616ece2d859	1053	}
mbed714	0:d616ece2d859	1054	}
mbed714	0:d616ece2d859	1055	/* End of ACK for new data processing. */
mbed714	0:d616ece2d859	1056
mbed714	0:d616ece2d859	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
mbed714	0:d616ece2d859	1058	pcb->rttest, pcb->rtseq, ackno));
mbed714	0:d616ece2d859	1059
mbed714	0:d616ece2d859	1060	/* RTT estimation calculations. This is done by checking if the
mbed714	0:d616ece2d859	1061	incoming segment acknowledges the segment we use to take a
mbed714	0:d616ece2d859	1062	round-trip time measurement. */
mbed714	0:d616ece2d859	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
mbed714	0:d616ece2d859	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
mbed714	0:d616ece2d859	1065	and a round-trip shouldn't be that long... */
mbed714	0:d616ece2d859	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
mbed714	0:d616ece2d859	1067
mbed714	0:d616ece2d859	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
mbed714	0:d616ece2d859	1069	m, m * TCP_SLOW_INTERVAL));
mbed714	0:d616ece2d859	1070
mbed714	0:d616ece2d859	1071	/* This is taken directly from VJs original code in his paper */
mbed714	0:d616ece2d859	1072	m = m - (pcb->sa >> 3);
mbed714	0:d616ece2d859	1073	pcb->sa += m;
mbed714	0:d616ece2d859	1074	if (m < 0) {
mbed714	0:d616ece2d859	1075	m = -m;
mbed714	0:d616ece2d859	1076	}
mbed714	0:d616ece2d859	1077	m = m - (pcb->sv >> 2);
mbed714	0:d616ece2d859	1078	pcb->sv += m;
mbed714	0:d616ece2d859	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
mbed714	0:d616ece2d859	1080
mbed714	0:d616ece2d859	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
mbed714	0:d616ece2d859	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
mbed714	0:d616ece2d859	1083
mbed714	0:d616ece2d859	1084	pcb->rttest = 0;
mbed714	0:d616ece2d859	1085	}
mbed714	0:d616ece2d859	1086	}
mbed714	0:d616ece2d859	1087
mbed714	0:d616ece2d859	1088	/* If the incoming segment contains data, we must process it
mbed714	0:d616ece2d859	1089	further. */
mbed714	0:d616ece2d859	1090	if (tcplen > 0) {
mbed714	0:d616ece2d859	1091	/* This code basically does three things:
mbed714	0:d616ece2d859	1092
mbed714	0:d616ece2d859	1093	+) If the incoming segment contains data that is the next
mbed714	0:d616ece2d859	1094	in-sequence data, this data is passed to the application. This
mbed714	0:d616ece2d859	1095	might involve trimming the first edge of the data. The rcv_nxt
mbed714	0:d616ece2d859	1096	variable and the advertised window are adjusted.
mbed714	0:d616ece2d859	1097
mbed714	0:d616ece2d859	1098	+) If the incoming segment has data that is above the next
mbed714	0:d616ece2d859	1099	sequence number expected (->rcv_nxt), the segment is placed on
mbed714	0:d616ece2d859	1100	the ->ooseq queue. This is done by finding the appropriate
mbed714	0:d616ece2d859	1101	place in the ->ooseq queue (which is ordered by sequence
mbed714	0:d616ece2d859	1102	number) and trim the segment in both ends if needed. An
mbed714	0:d616ece2d859	1103	immediate ACK is sent to indicate that we received an
mbed714	0:d616ece2d859	1104	out-of-sequence segment.
mbed714	0:d616ece2d859	1105
mbed714	0:d616ece2d859	1106	+) Finally, we check if the first segment on the ->ooseq queue
mbed714	0:d616ece2d859	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
mbed714	0:d616ece2d859	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
mbed714	0:d616ece2d859	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
mbed714	0:d616ece2d859	1110	segments that are now on sequence are chained onto the
mbed714	0:d616ece2d859	1111	incoming segment so that we only need to call the application
mbed714	0:d616ece2d859	1112	once.
mbed714	0:d616ece2d859	1113	*/
mbed714	0:d616ece2d859	1114
mbed714	0:d616ece2d859	1115	/* First, we check if we must trim the first edge. We have to do
mbed714	0:d616ece2d859	1116	this if the sequence number of the incoming segment is less
mbed714	0:d616ece2d859	1117	than rcv_nxt, and the sequence number plus the length of the
mbed714	0:d616ece2d859	1118	segment is larger than rcv_nxt. */
mbed714	0:d616ece2d859	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
mbed714	0:d616ece2d859	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
mbed714	0:d616ece2d859	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
mbed714	0:d616ece2d859	1122	/* Trimming the first edge is done by pushing the payload
mbed714	0:d616ece2d859	1123	pointer in the pbuf downwards. This is somewhat tricky since
mbed714	0:d616ece2d859	1124	we do not want to discard the full contents of the pbuf up to
mbed714	0:d616ece2d859	1125	the new starting point of the data since we have to keep the
mbed714	0:d616ece2d859	1126	TCP header which is present in the first pbuf in the chain.
mbed714	0:d616ece2d859	1127
mbed714	0:d616ece2d859	1128	What is done is really quite a nasty hack: the first pbuf in
mbed714	0:d616ece2d859	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
mbed714	0:d616ece2d859	1130	able to deallocate the whole pbuf, we cannot change this
mbed714	0:d616ece2d859	1131	inseg.p pointer to point to any of the later pbufs in the
mbed714	0:d616ece2d859	1132	chain. Instead, we point the ->payload pointer in the first
mbed714	0:d616ece2d859	1133	pbuf to data in one of the later pbufs. We also set the
mbed714	0:d616ece2d859	1134	inseg.data pointer to point to the right place. This way, the
mbed714	0:d616ece2d859	1135	->p pointer will still point to the first pbuf, but the
mbed714	0:d616ece2d859	1136	->p->payload pointer will point to data in another pbuf.
mbed714	0:d616ece2d859	1137
mbed714	0:d616ece2d859	1138	After we are done with adjusting the pbuf pointers we must
mbed714	0:d616ece2d859	1139	adjust the ->data pointer in the seg and the segment
mbed714	0:d616ece2d859	1140	length.*/
mbed714	0:d616ece2d859	1141
mbed714	0:d616ece2d859	1142	off = pcb->rcv_nxt - seqno;
mbed714	0:d616ece2d859	1143	p = inseg.p;
mbed714	0:d616ece2d859	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
mbed714	0:d616ece2d859	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
mbed714	0:d616ece2d859	1146	if (inseg.p->len < off) {
mbed714	0:d616ece2d859	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
mbed714	0:d616ece2d859	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
mbed714	0:d616ece2d859	1149	while (p->len < off) {
mbed714	0:d616ece2d859	1150	off -= p->len;
mbed714	0:d616ece2d859	1151	/* KJM following line changed (with addition of new_tot_len var)
mbed714	0:d616ece2d859	1152	to fix bug #9076
mbed714	0:d616ece2d859	1153	inseg.p->tot_len -= p->len; */
mbed714	0:d616ece2d859	1154	p->tot_len = new_tot_len;
mbed714	0:d616ece2d859	1155	p->len = 0;
mbed714	0:d616ece2d859	1156	p = p->next;
mbed714	0:d616ece2d859	1157	}
mbed714	0:d616ece2d859	1158	if(pbuf_header(p, (s16_t)-off)) {
mbed714	0:d616ece2d859	1159	/* Do we need to cope with this failing? Assert for now */
mbed714	0:d616ece2d859	1160	LWIP_ASSERT("pbuf_header failed", 0);
mbed714	0:d616ece2d859	1161	}
mbed714	0:d616ece2d859	1162	} else {
mbed714	0:d616ece2d859	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
mbed714	0:d616ece2d859	1164	/* Do we need to cope with this failing? Assert for now */
mbed714	0:d616ece2d859	1165	LWIP_ASSERT("pbuf_header failed", 0);
mbed714	0:d616ece2d859	1166	}
mbed714	0:d616ece2d859	1167	}
mbed714	0:d616ece2d859	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
mbed714	0:d616ece2d859	1169	to fix bug #9076 */
mbed714	0:d616ece2d859	1170	inseg.dataptr = p->payload;
mbed714	0:d616ece2d859	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
mbed714	0:d616ece2d859	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
mbed714	0:d616ece2d859	1173	}
mbed714	0:d616ece2d859	1174	else {
mbed714	0:d616ece2d859	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
mbed714	0:d616ece2d859	1176	/* the whole segment is < rcv_nxt */
mbed714	0:d616ece2d859	1177	/* must be a duplicate of a packet that has already been correctly handled */
mbed714	0:d616ece2d859	1178
mbed714	0:d616ece2d859	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
mbed714	0:d616ece2d859	1180	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	1181	}
mbed714	0:d616ece2d859	1182	}
mbed714	0:d616ece2d859	1183
mbed714	0:d616ece2d859	1184	/* The sequence number must be within the window (above rcv_nxt
mbed714	0:d616ece2d859	1185	and below rcv_nxt + rcv_wnd) in order to be further
mbed714	0:d616ece2d859	1186	processed. */
mbed714	0:d616ece2d859	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
mbed714	0:d616ece2d859	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
mbed714	0:d616ece2d859	1189	if (pcb->rcv_nxt == seqno) {
mbed714	0:d616ece2d859	1190	/* The incoming segment is the next in sequence. We check if
mbed714	0:d616ece2d859	1191	we have to trim the end of the segment and update rcv_nxt
mbed714	0:d616ece2d859	1192	and pass the data to the application. */
mbed714	0:d616ece2d859	1193	tcplen = TCP_TCPLEN(&inseg);
mbed714	0:d616ece2d859	1194
mbed714	0:d616ece2d859	1195	if (tcplen > pcb->rcv_wnd) {
mbed714	0:d616ece2d859	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
mbed714	0:d616ece2d859	1197	("tcp_receive: other end overran receive window"
mbed714	0:d616ece2d859	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
mbed714	0:d616ece2d859	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
mbed714	0:d616ece2d859	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	1201	/* Must remove the FIN from the header as we're trimming
mbed714	0:d616ece2d859	1202	* that byte of sequence-space from the packet */
mbed714	0:d616ece2d859	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
mbed714	0:d616ece2d859	1204	}
mbed714	0:d616ece2d859	1205	/* Adjust length of segment to fit in the window. */
mbed714	0:d616ece2d859	1206	inseg.len = pcb->rcv_wnd;
mbed714	0:d616ece2d859	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
mbed714	0:d616ece2d859	1208	inseg.len -= 1;
mbed714	0:d616ece2d859	1209	}
mbed714	0:d616ece2d859	1210	pbuf_realloc(inseg.p, inseg.len);
mbed714	0:d616ece2d859	1211	tcplen = TCP_TCPLEN(&inseg);
mbed714	0:d616ece2d859	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
mbed714	0:d616ece2d859	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
mbed714	0:d616ece2d859	1214	}
mbed714	0:d616ece2d859	1215	#if TCP_QUEUE_OOSEQ
mbed714	0:d616ece2d859	1216	/* Received in-sequence data, adjust ooseq data if:
mbed714	0:d616ece2d859	1217	- FIN has been received or
mbed714	0:d616ece2d859	1218	- inseq overlaps with ooseq */
mbed714	0:d616ece2d859	1219	if (pcb->ooseq != NULL) {
mbed714	0:d616ece2d859	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
mbed714	0:d616ece2d859	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
mbed714	0:d616ece2d859	1223	/* Received in-order FIN means anything that was received
mbed714	0:d616ece2d859	1224	* out of order must now have been received in-order, so
mbed714	0:d616ece2d859	1225	* bin the ooseq queue */
mbed714	0:d616ece2d859	1226	while (pcb->ooseq != NULL) {
mbed714	0:d616ece2d859	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
mbed714	0:d616ece2d859	1228	pcb->ooseq = pcb->ooseq->next;
mbed714	0:d616ece2d859	1229	tcp_seg_free(old_ooseq);
mbed714	0:d616ece2d859	1230	}
mbed714	0:d616ece2d859	1231	}
mbed714	0:d616ece2d859	1232	else {
mbed714	0:d616ece2d859	1233	next = pcb->ooseq;
mbed714	0:d616ece2d859	1234	/* Remove all segments on ooseq that are covered by inseg already.
mbed714	0:d616ece2d859	1235	* FIN is copied from ooseq to inseg if present. */
mbed714	0:d616ece2d859	1236	while (next &&
mbed714	0:d616ece2d859	1237	TCP_SEQ_GEQ(seqno + tcplen,
mbed714	0:d616ece2d859	1238	next->tcphdr->seqno + next->len)) {
mbed714	0:d616ece2d859	1239	/* inseg cannot have FIN here (already processed above) */
mbed714	0:d616ece2d859	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
mbed714	0:d616ece2d859	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
mbed714	0:d616ece2d859	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
mbed714	0:d616ece2d859	1243	tcplen = TCP_TCPLEN(&inseg);
mbed714	0:d616ece2d859	1244	}
mbed714	0:d616ece2d859	1245	prev = next;
mbed714	0:d616ece2d859	1246	next = next->next;
mbed714	0:d616ece2d859	1247	tcp_seg_free(prev);
mbed714	0:d616ece2d859	1248	}
mbed714	0:d616ece2d859	1249	/* Now trim right side of inseg if it overlaps with the first
mbed714	0:d616ece2d859	1250	* segment on ooseq */
mbed714	0:d616ece2d859	1251	if (next &&
mbed714	0:d616ece2d859	1252	TCP_SEQ_GT(seqno + tcplen,
mbed714	0:d616ece2d859	1253	next->tcphdr->seqno)) {
mbed714	0:d616ece2d859	1254	/* inseg cannot have FIN here (already processed above) */
mbed714	0:d616ece2d859	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
mbed714	0:d616ece2d859	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
mbed714	0:d616ece2d859	1257	inseg.len -= 1;
mbed714	0:d616ece2d859	1258	}
mbed714	0:d616ece2d859	1259	pbuf_realloc(inseg.p, inseg.len);
mbed714	0:d616ece2d859	1260	tcplen = TCP_TCPLEN(&inseg);
mbed714	0:d616ece2d859	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
mbed714	0:d616ece2d859	1262	(seqno + tcplen) == next->tcphdr->seqno);
mbed714	0:d616ece2d859	1263	}
mbed714	0:d616ece2d859	1264	pcb->ooseq = next;
mbed714	0:d616ece2d859	1265	}
mbed714	0:d616ece2d859	1266	}
mbed714	0:d616ece2d859	1267	#endif /* TCP_QUEUE_OOSEQ */
mbed714	0:d616ece2d859	1268
mbed714	0:d616ece2d859	1269	pcb->rcv_nxt = seqno + tcplen;
mbed714	0:d616ece2d859	1270
mbed714	0:d616ece2d859	1271	/* Update the receiver's (our) window. */
mbed714	0:d616ece2d859	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
mbed714	0:d616ece2d859	1273	pcb->rcv_wnd -= tcplen;
mbed714	0:d616ece2d859	1274
mbed714	0:d616ece2d859	1275	tcp_update_rcv_ann_wnd(pcb);
mbed714	0:d616ece2d859	1276
mbed714	0:d616ece2d859	1277	/* If there is data in the segment, we make preparations to
mbed714	0:d616ece2d859	1278	pass this up to the application. The ->recv_data variable
mbed714	0:d616ece2d859	1279	is used for holding the pbuf that goes to the
mbed714	0:d616ece2d859	1280	application. The code for reassembling out-of-sequence data
mbed714	0:d616ece2d859	1281	chains its data on this pbuf as well.
mbed714	0:d616ece2d859	1282
mbed714	0:d616ece2d859	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
mbed714	0:d616ece2d859	1284	be used to indicate to the application that the remote side has
mbed714	0:d616ece2d859	1285	closed its end of the connection. */
mbed714	0:d616ece2d859	1286	if (inseg.p->tot_len > 0) {
mbed714	0:d616ece2d859	1287	recv_data = inseg.p;
mbed714	0:d616ece2d859	1288	/* Since this pbuf now is the responsibility of the
mbed714	0:d616ece2d859	1289	application, we delete our reference to it so that we won't
mbed714	0:d616ece2d859	1290	(mistakingly) deallocate it. */
mbed714	0:d616ece2d859	1291	inseg.p = NULL;
mbed714	0:d616ece2d859	1292	}
mbed714	0:d616ece2d859	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
mbed714	0:d616ece2d859	1295	recv_flags \|= TF_GOT_FIN;
mbed714	0:d616ece2d859	1296	}
mbed714	0:d616ece2d859	1297
mbed714	0:d616ece2d859	1298	#if TCP_QUEUE_OOSEQ
mbed714	0:d616ece2d859	1299	/* We now check if we have segments on the ->ooseq queue that
mbed714	0:d616ece2d859	1300	are now in sequence. */
mbed714	0:d616ece2d859	1301	while (pcb->ooseq != NULL &&
mbed714	0:d616ece2d859	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
mbed714	0:d616ece2d859	1303
mbed714	0:d616ece2d859	1304	cseg = pcb->ooseq;
mbed714	0:d616ece2d859	1305	seqno = pcb->ooseq->tcphdr->seqno;
mbed714	0:d616ece2d859	1306
mbed714	0:d616ece2d859	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
mbed714	0:d616ece2d859	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
mbed714	0:d616ece2d859	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
mbed714	0:d616ece2d859	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
mbed714	0:d616ece2d859	1311
mbed714	0:d616ece2d859	1312	tcp_update_rcv_ann_wnd(pcb);
mbed714	0:d616ece2d859	1313
mbed714	0:d616ece2d859	1314	if (cseg->p->tot_len > 0) {
mbed714	0:d616ece2d859	1315	/* Chain this pbuf onto the pbuf that we will pass to
mbed714	0:d616ece2d859	1316	the application. */
mbed714	0:d616ece2d859	1317	if (recv_data) {
mbed714	0:d616ece2d859	1318	pbuf_cat(recv_data, cseg->p);
mbed714	0:d616ece2d859	1319	} else {
mbed714	0:d616ece2d859	1320	recv_data = cseg->p;
mbed714	0:d616ece2d859	1321	}
mbed714	0:d616ece2d859	1322	cseg->p = NULL;
mbed714	0:d616ece2d859	1323	}
mbed714	0:d616ece2d859	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
mbed714	0:d616ece2d859	1326	recv_flags \|= TF_GOT_FIN;
mbed714	0:d616ece2d859	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
mbed714	0:d616ece2d859	1328	pcb->state = CLOSE_WAIT;
mbed714	0:d616ece2d859	1329	}
mbed714	0:d616ece2d859	1330	}
mbed714	0:d616ece2d859	1331
mbed714	0:d616ece2d859	1332	pcb->ooseq = cseg->next;
mbed714	0:d616ece2d859	1333	tcp_seg_free(cseg);
mbed714	0:d616ece2d859	1334	}
mbed714	0:d616ece2d859	1335	#endif /* TCP_QUEUE_OOSEQ */
mbed714	0:d616ece2d859	1336
mbed714	0:d616ece2d859	1337
mbed714	0:d616ece2d859	1338	/* Acknowledge the segment(s). */
mbed714	0:d616ece2d859	1339	tcp_ack(pcb);
mbed714	0:d616ece2d859	1340
mbed714	0:d616ece2d859	1341	} else {
mbed714	0:d616ece2d859	1342	/* We get here if the incoming segment is out-of-sequence. */
mbed714	0:d616ece2d859	1343	tcp_send_empty_ack(pcb);
mbed714	0:d616ece2d859	1344	#if TCP_QUEUE_OOSEQ
mbed714	0:d616ece2d859	1345	/* We queue the segment on the ->ooseq queue. */
mbed714	0:d616ece2d859	1346	if (pcb->ooseq == NULL) {
mbed714	0:d616ece2d859	1347	pcb->ooseq = tcp_seg_copy(&inseg);
mbed714	0:d616ece2d859	1348	} else {
mbed714	0:d616ece2d859	1349	/* If the queue is not empty, we walk through the queue and
mbed714	0:d616ece2d859	1350	try to find a place where the sequence number of the
mbed714	0:d616ece2d859	1351	incoming segment is between the sequence numbers of the
mbed714	0:d616ece2d859	1352	previous and the next segment on the ->ooseq queue. That is
mbed714	0:d616ece2d859	1353	the place where we put the incoming segment. If needed, we
mbed714	0:d616ece2d859	1354	trim the second edges of the previous and the incoming
mbed714	0:d616ece2d859	1355	segment so that it will fit into the sequence.
mbed714	0:d616ece2d859	1356
mbed714	0:d616ece2d859	1357	If the incoming segment has the same sequence number as a
mbed714	0:d616ece2d859	1358	segment on the ->ooseq queue, we discard the segment that
mbed714	0:d616ece2d859	1359	contains less data. */
mbed714	0:d616ece2d859	1360
mbed714	0:d616ece2d859	1361	prev = NULL;
mbed714	0:d616ece2d859	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
mbed714	0:d616ece2d859	1363	if (seqno == next->tcphdr->seqno) {
mbed714	0:d616ece2d859	1364	/* The sequence number of the incoming segment is the
mbed714	0:d616ece2d859	1365	same as the sequence number of the segment on
mbed714	0:d616ece2d859	1366	->ooseq. We check the lengths to see which one to
mbed714	0:d616ece2d859	1367	discard. */
mbed714	0:d616ece2d859	1368	if (inseg.len > next->len) {
mbed714	0:d616ece2d859	1369	/* The incoming segment is larger than the old
mbed714	0:d616ece2d859	1370	segment. We replace some segments with the new
mbed714	0:d616ece2d859	1371	one. */
mbed714	0:d616ece2d859	1372	cseg = tcp_seg_copy(&inseg);
mbed714	0:d616ece2d859	1373	if (cseg != NULL) {
mbed714	0:d616ece2d859	1374	if (prev != NULL) {
mbed714	0:d616ece2d859	1375	prev->next = cseg;
mbed714	0:d616ece2d859	1376	} else {
mbed714	0:d616ece2d859	1377	pcb->ooseq = cseg;
mbed714	0:d616ece2d859	1378	}
mbed714	0:d616ece2d859	1379	tcp_oos_insert_segment(cseg, next);
mbed714	0:d616ece2d859	1380	}
mbed714	0:d616ece2d859	1381	break;
mbed714	0:d616ece2d859	1382	} else {
mbed714	0:d616ece2d859	1383	/* Either the lenghts are the same or the incoming
mbed714	0:d616ece2d859	1384	segment was smaller than the old one; in either
mbed714	0:d616ece2d859	1385	case, we ditch the incoming segment. */
mbed714	0:d616ece2d859	1386	break;
mbed714	0:d616ece2d859	1387	}
mbed714	0:d616ece2d859	1388	} else {
mbed714	0:d616ece2d859	1389	if (prev == NULL) {
mbed714	0:d616ece2d859	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
mbed714	0:d616ece2d859	1391	/* The sequence number of the incoming segment is lower
mbed714	0:d616ece2d859	1392	than the sequence number of the first segment on the
mbed714	0:d616ece2d859	1393	queue. We put the incoming segment first on the
mbed714	0:d616ece2d859	1394	queue. */
mbed714	0:d616ece2d859	1395	cseg = tcp_seg_copy(&inseg);
mbed714	0:d616ece2d859	1396	if (cseg != NULL) {
mbed714	0:d616ece2d859	1397	pcb->ooseq = cseg;
mbed714	0:d616ece2d859	1398	tcp_oos_insert_segment(cseg, next);
mbed714	0:d616ece2d859	1399	}
mbed714	0:d616ece2d859	1400	break;
mbed714	0:d616ece2d859	1401	}
mbed714	0:d616ece2d859	1402	} else {
mbed714	0:d616ece2d859	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
mbed714	0:d616ece2d859	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
mbed714	0:d616ece2d859	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
mbed714	0:d616ece2d859	1406	/* The sequence number of the incoming segment is in
mbed714	0:d616ece2d859	1407	between the sequence numbers of the previous and
mbed714	0:d616ece2d859	1408	the next segment on ->ooseq. We trim trim the previous
mbed714	0:d616ece2d859	1409	segment, delete next segments that included in received segment
mbed714	0:d616ece2d859	1410	and trim received, if needed. */
mbed714	0:d616ece2d859	1411	cseg = tcp_seg_copy(&inseg);
mbed714	0:d616ece2d859	1412	if (cseg != NULL) {
mbed714	0:d616ece2d859	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
mbed714	0:d616ece2d859	1414	/* We need to trim the prev segment. */
mbed714	0:d616ece2d859	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
mbed714	0:d616ece2d859	1416	pbuf_realloc(prev->p, prev->len);
mbed714	0:d616ece2d859	1417	}
mbed714	0:d616ece2d859	1418	prev->next = cseg;
mbed714	0:d616ece2d859	1419	tcp_oos_insert_segment(cseg, next);
mbed714	0:d616ece2d859	1420	}
mbed714	0:d616ece2d859	1421	break;
mbed714	0:d616ece2d859	1422	}
mbed714	0:d616ece2d859	1423	}
mbed714	0:d616ece2d859	1424	/* If the "next" segment is the last segment on the
mbed714	0:d616ece2d859	1425	ooseq queue, we add the incoming segment to the end
mbed714	0:d616ece2d859	1426	of the list. */
mbed714	0:d616ece2d859	1427	if (next->next == NULL &&
mbed714	0:d616ece2d859	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
mbed714	0:d616ece2d859	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	1430	/* segment "next" already contains all data */
mbed714	0:d616ece2d859	1431	break;
mbed714	0:d616ece2d859	1432	}
mbed714	0:d616ece2d859	1433	next->next = tcp_seg_copy(&inseg);
mbed714	0:d616ece2d859	1434	if (next->next != NULL) {
mbed714	0:d616ece2d859	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
mbed714	0:d616ece2d859	1436	/* We need to trim the last segment. */
mbed714	0:d616ece2d859	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
mbed714	0:d616ece2d859	1438	pbuf_realloc(next->p, next->len);
mbed714	0:d616ece2d859	1439	}
mbed714	0:d616ece2d859	1440	/* check if the remote side overruns our receive window */
mbed714	0:d616ece2d859	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
mbed714	0:d616ece2d859	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
mbed714	0:d616ece2d859	1443	("tcp_receive: other end overran receive window"
mbed714	0:d616ece2d859	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
mbed714	0:d616ece2d859	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
mbed714	0:d616ece2d859	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
mbed714	0:d616ece2d859	1447	/* Must remove the FIN from the header as we're trimming
mbed714	0:d616ece2d859	1448	* that byte of sequence-space from the packet */
mbed714	0:d616ece2d859	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
mbed714	0:d616ece2d859	1450	}
mbed714	0:d616ece2d859	1451	/* Adjust length of segment to fit in the window. */
mbed714	0:d616ece2d859	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
mbed714	0:d616ece2d859	1453	pbuf_realloc(next->next->p, next->next->len);
mbed714	0:d616ece2d859	1454	tcplen = TCP_TCPLEN(next->next);
mbed714	0:d616ece2d859	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
mbed714	0:d616ece2d859	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
mbed714	0:d616ece2d859	1457	}
mbed714	0:d616ece2d859	1458	}
mbed714	0:d616ece2d859	1459	break;
mbed714	0:d616ece2d859	1460	}
mbed714	0:d616ece2d859	1461	}
mbed714	0:d616ece2d859	1462	prev = next;
mbed714	0:d616ece2d859	1463	}
mbed714	0:d616ece2d859	1464	}
mbed714	0:d616ece2d859	1465	#endif /* TCP_QUEUE_OOSEQ */
mbed714	0:d616ece2d859	1466
mbed714	0:d616ece2d859	1467	}
mbed714	0:d616ece2d859	1468	} else {
mbed714	0:d616ece2d859	1469	/* The incoming segment is not withing the window. */
mbed714	0:d616ece2d859	1470	tcp_send_empty_ack(pcb);
mbed714	0:d616ece2d859	1471	}
mbed714	0:d616ece2d859	1472	} else {
mbed714	0:d616ece2d859	1473	/* Segments with length 0 is taken care of here. Segments that
mbed714	0:d616ece2d859	1474	fall out of the window are ACKed. */
mbed714	0:d616ece2d859	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
mbed714	0:d616ece2d859	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
mbed714	0:d616ece2d859	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
mbed714	0:d616ece2d859	1478	tcp_ack_now(pcb);
mbed714	0:d616ece2d859	1479	}
mbed714	0:d616ece2d859	1480	}
mbed714	0:d616ece2d859	1481	}
mbed714	0:d616ece2d859	1482
mbed714	0:d616ece2d859	1483	/**
mbed714	0:d616ece2d859	1484	* Parses the options contained in the incoming segment.
mbed714	0:d616ece2d859	1485	*
mbed714	0:d616ece2d859	1486	* Called from tcp_listen_input() and tcp_process().
mbed714	0:d616ece2d859	1487	* Currently, only the MSS option is supported!
mbed714	0:d616ece2d859	1488	*
mbed714	0:d616ece2d859	1489	* @param pcb the tcp_pcb for which a segment arrived
mbed714	0:d616ece2d859	1490	*/
mbed714	0:d616ece2d859	1491	static void
mbed714	0:d616ece2d859	1492	tcp_parseopt(struct tcp_pcb *pcb)
mbed714	0:d616ece2d859	1493	{
mbed714	0:d616ece2d859	1494	u16_t c, max_c;
mbed714	0:d616ece2d859	1495	u16_t mss;
mbed714	0:d616ece2d859	1496	u8_t *opts, opt;
mbed714	0:d616ece2d859	1497	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	1498	u32_t tsval;
mbed714	0:d616ece2d859	1499	#endif
mbed714	0:d616ece2d859	1500
mbed714	0:d616ece2d859	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
mbed714	0:d616ece2d859	1502
mbed714	0:d616ece2d859	1503	/* Parse the TCP MSS option, if present. */
mbed714	0:d616ece2d859	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
mbed714	0:d616ece2d859	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
mbed714	0:d616ece2d859	1506	for (c = 0; c < max_c; ) {
mbed714	0:d616ece2d859	1507	opt = opts[c];
mbed714	0:d616ece2d859	1508	switch (opt) {
mbed714	0:d616ece2d859	1509	case 0x00:
mbed714	0:d616ece2d859	1510	/* End of options. */
mbed714	0:d616ece2d859	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
mbed714	0:d616ece2d859	1512	return;
mbed714	0:d616ece2d859	1513	case 0x01:
mbed714	0:d616ece2d859	1514	/* NOP option. */
mbed714	0:d616ece2d859	1515	++c;
mbed714	0:d616ece2d859	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
mbed714	0:d616ece2d859	1517	break;
mbed714	0:d616ece2d859	1518	case 0x02:
mbed714	0:d616ece2d859	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
mbed714	0:d616ece2d859	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
mbed714	0:d616ece2d859	1521	/* Bad length */
mbed714	0:d616ece2d859	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
mbed714	0:d616ece2d859	1523	return;
mbed714	0:d616ece2d859	1524	}
mbed714	0:d616ece2d859	1525	/* An MSS option with the right option length. */
mbed714	0:d616ece2d859	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
mbed714	0:d616ece2d859	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
mbed714	0:d616ece2d859	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
mbed714	0:d616ece2d859	1529	/* Advance to next option */
mbed714	0:d616ece2d859	1530	c += 0x04;
mbed714	0:d616ece2d859	1531	break;
mbed714	0:d616ece2d859	1532	#if LWIP_TCP_TIMESTAMPS
mbed714	0:d616ece2d859	1533	case 0x08:
mbed714	0:d616ece2d859	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
mbed714	0:d616ece2d859	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
mbed714	0:d616ece2d859	1536	/* Bad length */
mbed714	0:d616ece2d859	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
mbed714	0:d616ece2d859	1538	return;
mbed714	0:d616ece2d859	1539	}
mbed714	0:d616ece2d859	1540	/* TCP timestamp option with valid length */
mbed714	0:d616ece2d859	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
mbed714	0:d616ece2d859	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
mbed714	0:d616ece2d859	1543	if (flags & TCP_SYN) {
mbed714	0:d616ece2d859	1544	pcb->ts_recent = ntohl(tsval);
mbed714	0:d616ece2d859	1545	pcb->flags \|= TF_TIMESTAMP;
mbed714	0:d616ece2d859	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
mbed714	0:d616ece2d859	1547	pcb->ts_recent = ntohl(tsval);
mbed714	0:d616ece2d859	1548	}
mbed714	0:d616ece2d859	1549	/* Advance to next option */
mbed714	0:d616ece2d859	1550	c += 0x0A;
mbed714	0:d616ece2d859	1551	break;
mbed714	0:d616ece2d859	1552	#endif
mbed714	0:d616ece2d859	1553	default:
mbed714	0:d616ece2d859	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
mbed714	0:d616ece2d859	1555	if (opts[c + 1] == 0) {
mbed714	0:d616ece2d859	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
mbed714	0:d616ece2d859	1557	/* If the length field is zero, the options are malformed
mbed714	0:d616ece2d859	1558	and we don't process them further. */
mbed714	0:d616ece2d859	1559	return;
mbed714	0:d616ece2d859	1560	}
mbed714	0:d616ece2d859	1561	/* All other options have a length field, so that we easily
mbed714	0:d616ece2d859	1562	can skip past them. */
mbed714	0:d616ece2d859	1563	c += opts[c + 1];
mbed714	0:d616ece2d859	1564	}
mbed714	0:d616ece2d859	1565	}
mbed714	0:d616ece2d859	1566	}
mbed714	0:d616ece2d859	1567	}
mbed714	0:d616ece2d859	1568
mbed714	0:d616ece2d859	1569	#endif /* LWIP_TCP */

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Type:	Library
Created:	18 Sep 2010
Imports:	1
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

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lwip/core/tcp_in.c@0:d616ece2d859, 2010-09-18 (annotated)

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