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lwip/core/tcp_in.c@0:ac21159e27f4, 2010-07-02 (annotated)

Committer:: darran
Date:: Fri Jul 02 17:21:58 2010 +0000
Revision:: 0:ac21159e27f4

Who changed what in which revision?

User	Revision	Line number	New contents of line
darran	0:ac21159e27f4	1	/**
darran	0:ac21159e27f4	2	* @file
darran	0:ac21159e27f4	3	* Transmission Control Protocol, incoming traffic
darran	0:ac21159e27f4	4	*
darran	0:ac21159e27f4	5	* The input processing functions of the TCP layer.
darran	0:ac21159e27f4	6	*
darran	0:ac21159e27f4	7	* These functions are generally called in the order (ip_input() ->)
darran	0:ac21159e27f4	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
darran	0:ac21159e27f4	9	*
darran	0:ac21159e27f4	10	*/
darran	0:ac21159e27f4	11
darran	0:ac21159e27f4	12	/*
darran	0:ac21159e27f4	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
darran	0:ac21159e27f4	14	* All rights reserved.
darran	0:ac21159e27f4	15	*
darran	0:ac21159e27f4	16	* Redistribution and use in source and binary forms, with or without modification,
darran	0:ac21159e27f4	17	* are permitted provided that the following conditions are met:
darran	0:ac21159e27f4	18	*
darran	0:ac21159e27f4	19	* 1. Redistributions of source code must retain the above copyright notice,
darran	0:ac21159e27f4	20	* this list of conditions and the following disclaimer.
darran	0:ac21159e27f4	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
darran	0:ac21159e27f4	22	* this list of conditions and the following disclaimer in the documentation
darran	0:ac21159e27f4	23	* and/or other materials provided with the distribution.
darran	0:ac21159e27f4	24	* 3. The name of the author may not be used to endorse or promote products
darran	0:ac21159e27f4	25	* derived from this software without specific prior written permission.
darran	0:ac21159e27f4	26	*
darran	0:ac21159e27f4	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
darran	0:ac21159e27f4	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
darran	0:ac21159e27f4	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
darran	0:ac21159e27f4	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
darran	0:ac21159e27f4	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
darran	0:ac21159e27f4	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
darran	0:ac21159e27f4	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
darran	0:ac21159e27f4	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
darran	0:ac21159e27f4	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
darran	0:ac21159e27f4	36	* OF SUCH DAMAGE.
darran	0:ac21159e27f4	37	*
darran	0:ac21159e27f4	38	* This file is part of the lwIP TCP/IP stack.
darran	0:ac21159e27f4	39	*
darran	0:ac21159e27f4	40	* Author: Adam Dunkels <adam@sics.se>
darran	0:ac21159e27f4	41	*
darran	0:ac21159e27f4	42	*/
darran	0:ac21159e27f4	43
darran	0:ac21159e27f4	44	#include "lwip/opt.h"
darran	0:ac21159e27f4	45
darran	0:ac21159e27f4	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
darran	0:ac21159e27f4	47
darran	0:ac21159e27f4	48	#include "lwip/tcp_impl.h"
darran	0:ac21159e27f4	49	#include "lwip/def.h"
darran	0:ac21159e27f4	50	#include "lwip/ip_addr.h"
darran	0:ac21159e27f4	51	#include "lwip/netif.h"
darran	0:ac21159e27f4	52	#include "lwip/mem.h"
darran	0:ac21159e27f4	53	#include "lwip/memp.h"
darran	0:ac21159e27f4	54	#include "lwip/inet_chksum.h"
darran	0:ac21159e27f4	55	#include "lwip/stats.h"
darran	0:ac21159e27f4	56	#include "lwip/snmp.h"
darran	0:ac21159e27f4	57	#include "arch/perf.h"
darran	0:ac21159e27f4	58
darran	0:ac21159e27f4	59	/* These variables are global to all functions involved in the input
darran	0:ac21159e27f4	60	processing of TCP segments. They are set by the tcp_input()
darran	0:ac21159e27f4	61	function. */
darran	0:ac21159e27f4	62	static struct tcp_seg inseg;
darran	0:ac21159e27f4	63	static struct tcp_hdr *tcphdr;
darran	0:ac21159e27f4	64	static struct ip_hdr *iphdr;
darran	0:ac21159e27f4	65	static u32_t seqno, ackno;
darran	0:ac21159e27f4	66	static u8_t flags;
darran	0:ac21159e27f4	67	static u16_t tcplen;
darran	0:ac21159e27f4	68
darran	0:ac21159e27f4	69	static u8_t recv_flags;
darran	0:ac21159e27f4	70	static struct pbuf *recv_data;
darran	0:ac21159e27f4	71
darran	0:ac21159e27f4	72	struct tcp_pcb *tcp_input_pcb;
darran	0:ac21159e27f4	73
darran	0:ac21159e27f4	74	/* Forward declarations. */
darran	0:ac21159e27f4	75	static err_t tcp_process(struct tcp_pcb *pcb);
darran	0:ac21159e27f4	76	static void tcp_receive(struct tcp_pcb *pcb);
darran	0:ac21159e27f4	77	static void tcp_parseopt(struct tcp_pcb *pcb);
darran	0:ac21159e27f4	78
darran	0:ac21159e27f4	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
darran	0:ac21159e27f4	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
darran	0:ac21159e27f4	81
darran	0:ac21159e27f4	82	/**
darran	0:ac21159e27f4	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
darran	0:ac21159e27f4	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
darran	0:ac21159e27f4	85	* the TCP finite state machine. This function is called by the IP layer (in
darran	0:ac21159e27f4	86	* ip_input()).
darran	0:ac21159e27f4	87	*
darran	0:ac21159e27f4	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
darran	0:ac21159e27f4	89	* @param inp network interface on which this segment was received
darran	0:ac21159e27f4	90	*/
darran	0:ac21159e27f4	91	void
darran	0:ac21159e27f4	92	tcp_input(struct pbuf p, struct netif inp)
darran	0:ac21159e27f4	93	{
darran	0:ac21159e27f4	94	struct tcp_pcb pcb, prev;
darran	0:ac21159e27f4	95	struct tcp_pcb_listen *lpcb;
darran	0:ac21159e27f4	96	u8_t hdrlen;
darran	0:ac21159e27f4	97	err_t err;
darran	0:ac21159e27f4	98
darran	0:ac21159e27f4	99	PERF_START;
darran	0:ac21159e27f4	100
darran	0:ac21159e27f4	101	TCP_STATS_INC(tcp.recv);
darran	0:ac21159e27f4	102	snmp_inc_tcpinsegs();
darran	0:ac21159e27f4	103
darran	0:ac21159e27f4	104	iphdr = (struct ip_hdr *)p->payload;
darran	0:ac21159e27f4	105	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
darran	0:ac21159e27f4	106
darran	0:ac21159e27f4	107	#if TCP_INPUT_DEBUG
darran	0:ac21159e27f4	108	tcp_debug_print(tcphdr);
darran	0:ac21159e27f4	109	#endif
darran	0:ac21159e27f4	110
darran	0:ac21159e27f4	111	/* remove header from payload */
darran	0:ac21159e27f4	112	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
darran	0:ac21159e27f4	113	/* drop short packets */
darran	0:ac21159e27f4	114	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
darran	0:ac21159e27f4	115	TCP_STATS_INC(tcp.lenerr);
darran	0:ac21159e27f4	116	TCP_STATS_INC(tcp.drop);
darran	0:ac21159e27f4	117	snmp_inc_tcpinerrs();
darran	0:ac21159e27f4	118	pbuf_free(p);
darran	0:ac21159e27f4	119	return;
darran	0:ac21159e27f4	120	}
darran	0:ac21159e27f4	121
darran	0:ac21159e27f4	122	/* Don't even process incoming broadcasts/multicasts. */
darran	0:ac21159e27f4	123	if (ip_addr_isbroadcast(&(iphdr->dest), inp) \|\|
darran	0:ac21159e27f4	124	ip_addr_ismulticast(&(iphdr->dest))) {
darran	0:ac21159e27f4	125	TCP_STATS_INC(tcp.proterr);
darran	0:ac21159e27f4	126	TCP_STATS_INC(tcp.drop);
darran	0:ac21159e27f4	127	snmp_inc_tcpinerrs();
darran	0:ac21159e27f4	128	pbuf_free(p);
darran	0:ac21159e27f4	129	return;
darran	0:ac21159e27f4	130	}
darran	0:ac21159e27f4	131
darran	0:ac21159e27f4	132	#if CHECKSUM_CHECK_TCP
darran	0:ac21159e27f4	133	/* Verify TCP checksum. */
darran	0:ac21159e27f4	134	if (inet_chksum_pseudo(p, &iphdr->src, &iphdr->dest,
darran	0:ac21159e27f4	135	IP_PROTO_TCP, p->tot_len) != 0) {
darran	0:ac21159e27f4	136	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
darran	0:ac21159e27f4	137	inet_chksum_pseudo(p, &iphdr->src, &iphdr->dest,
darran	0:ac21159e27f4	138	IP_PROTO_TCP, p->tot_len)));
darran	0:ac21159e27f4	139	#if TCP_DEBUG
darran	0:ac21159e27f4	140	tcp_debug_print(tcphdr);
darran	0:ac21159e27f4	141	#endif /* TCP_DEBUG */
darran	0:ac21159e27f4	142	TCP_STATS_INC(tcp.chkerr);
darran	0:ac21159e27f4	143	TCP_STATS_INC(tcp.drop);
darran	0:ac21159e27f4	144	snmp_inc_tcpinerrs();
darran	0:ac21159e27f4	145	pbuf_free(p);
darran	0:ac21159e27f4	146	return;
darran	0:ac21159e27f4	147	}
darran	0:ac21159e27f4	148	#endif
darran	0:ac21159e27f4	149
darran	0:ac21159e27f4	150	/* Move the payload pointer in the pbuf so that it points to the
darran	0:ac21159e27f4	151	TCP data instead of the TCP header. */
darran	0:ac21159e27f4	152	hdrlen = TCPH_HDRLEN(tcphdr);
darran	0:ac21159e27f4	153	if(pbuf_header(p, -(hdrlen * 4))){
darran	0:ac21159e27f4	154	/* drop short packets */
darran	0:ac21159e27f4	155	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
darran	0:ac21159e27f4	156	TCP_STATS_INC(tcp.lenerr);
darran	0:ac21159e27f4	157	TCP_STATS_INC(tcp.drop);
darran	0:ac21159e27f4	158	snmp_inc_tcpinerrs();
darran	0:ac21159e27f4	159	pbuf_free(p);
darran	0:ac21159e27f4	160	return;
darran	0:ac21159e27f4	161	}
darran	0:ac21159e27f4	162
darran	0:ac21159e27f4	163	/* Convert fields in TCP header to host byte order. */
darran	0:ac21159e27f4	164	tcphdr->src = ntohs(tcphdr->src);
darran	0:ac21159e27f4	165	tcphdr->dest = ntohs(tcphdr->dest);
darran	0:ac21159e27f4	166	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
darran	0:ac21159e27f4	167	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
darran	0:ac21159e27f4	168	tcphdr->wnd = ntohs(tcphdr->wnd);
darran	0:ac21159e27f4	169
darran	0:ac21159e27f4	170	flags = TCPH_FLAGS(tcphdr);
darran	0:ac21159e27f4	171	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
darran	0:ac21159e27f4	172
darran	0:ac21159e27f4	173	/* Demultiplex an incoming segment. First, we check if it is destined
darran	0:ac21159e27f4	174	for an active connection. */
darran	0:ac21159e27f4	175	prev = NULL;
darran	0:ac21159e27f4	176
darran	0:ac21159e27f4	177
darran	0:ac21159e27f4	178	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
darran	0:ac21159e27f4	179	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
darran	0:ac21159e27f4	180	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
darran	0:ac21159e27f4	181	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
darran	0:ac21159e27f4	182	if (pcb->remote_port == tcphdr->src &&
darran	0:ac21159e27f4	183	pcb->local_port == tcphdr->dest &&
darran	0:ac21159e27f4	184	ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
darran	0:ac21159e27f4	185	ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
darran	0:ac21159e27f4	186
darran	0:ac21159e27f4	187	/* Move this PCB to the front of the list so that subsequent
darran	0:ac21159e27f4	188	lookups will be faster (we exploit locality in TCP segment
darran	0:ac21159e27f4	189	arrivals). */
darran	0:ac21159e27f4	190	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
darran	0:ac21159e27f4	191	if (prev != NULL) {
darran	0:ac21159e27f4	192	prev->next = pcb->next;
darran	0:ac21159e27f4	193	pcb->next = tcp_active_pcbs;
darran	0:ac21159e27f4	194	tcp_active_pcbs = pcb;
darran	0:ac21159e27f4	195	}
darran	0:ac21159e27f4	196	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
darran	0:ac21159e27f4	197	break;
darran	0:ac21159e27f4	198	}
darran	0:ac21159e27f4	199	prev = pcb;
darran	0:ac21159e27f4	200	}
darran	0:ac21159e27f4	201
darran	0:ac21159e27f4	202	if (pcb == NULL) {
darran	0:ac21159e27f4	203	/* If it did not go to an active connection, we check the connections
darran	0:ac21159e27f4	204	in the TIME-WAIT state. */
darran	0:ac21159e27f4	205	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
darran	0:ac21159e27f4	206	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
darran	0:ac21159e27f4	207	if (pcb->remote_port == tcphdr->src &&
darran	0:ac21159e27f4	208	pcb->local_port == tcphdr->dest &&
darran	0:ac21159e27f4	209	ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
darran	0:ac21159e27f4	210	ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
darran	0:ac21159e27f4	211	/* We don't really care enough to move this PCB to the front
darran	0:ac21159e27f4	212	of the list since we are not very likely to receive that
darran	0:ac21159e27f4	213	many segments for connections in TIME-WAIT. */
darran	0:ac21159e27f4	214	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
darran	0:ac21159e27f4	215	tcp_timewait_input(pcb);
darran	0:ac21159e27f4	216	pbuf_free(p);
darran	0:ac21159e27f4	217	return;
darran	0:ac21159e27f4	218	}
darran	0:ac21159e27f4	219	}
darran	0:ac21159e27f4	220
darran	0:ac21159e27f4	221	/* Finally, if we still did not get a match, we check all PCBs that
darran	0:ac21159e27f4	222	are LISTENing for incoming connections. */
darran	0:ac21159e27f4	223	prev = NULL;
darran	0:ac21159e27f4	224	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
darran	0:ac21159e27f4	225	if ((ip_addr_isany(&(lpcb->local_ip)) \|\|
darran	0:ac21159e27f4	226	ip_addr_cmp(&(lpcb->local_ip), &(iphdr->dest))) &&
darran	0:ac21159e27f4	227	lpcb->local_port == tcphdr->dest) {
darran	0:ac21159e27f4	228	/* Move this PCB to the front of the list so that subsequent
darran	0:ac21159e27f4	229	lookups will be faster (we exploit locality in TCP segment
darran	0:ac21159e27f4	230	arrivals). */
darran	0:ac21159e27f4	231	if (prev != NULL) {
darran	0:ac21159e27f4	232	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
darran	0:ac21159e27f4	233	/* our successor is the remainder of the listening list */
darran	0:ac21159e27f4	234	lpcb->next = tcp_listen_pcbs.listen_pcbs;
darran	0:ac21159e27f4	235	/* put this listening pcb at the head of the listening list */
darran	0:ac21159e27f4	236	tcp_listen_pcbs.listen_pcbs = lpcb;
darran	0:ac21159e27f4	237	}
darran	0:ac21159e27f4	238
darran	0:ac21159e27f4	239	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
darran	0:ac21159e27f4	240	tcp_listen_input(lpcb);
darran	0:ac21159e27f4	241	pbuf_free(p);
darran	0:ac21159e27f4	242	return;
darran	0:ac21159e27f4	243	}
darran	0:ac21159e27f4	244	prev = (struct tcp_pcb *)lpcb;
darran	0:ac21159e27f4	245	}
darran	0:ac21159e27f4	246	}
darran	0:ac21159e27f4	247
darran	0:ac21159e27f4	248	#if TCP_INPUT_DEBUG
darran	0:ac21159e27f4	249	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
darran	0:ac21159e27f4	250	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
darran	0:ac21159e27f4	251	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
darran	0:ac21159e27f4	252	#endif /* TCP_INPUT_DEBUG */
darran	0:ac21159e27f4	253
darran	0:ac21159e27f4	254
darran	0:ac21159e27f4	255	if (pcb != NULL) {
darran	0:ac21159e27f4	256	/* The incoming segment belongs to a connection. */
darran	0:ac21159e27f4	257	#if TCP_INPUT_DEBUG
darran	0:ac21159e27f4	258	#if TCP_DEBUG
darran	0:ac21159e27f4	259	tcp_debug_print_state(pcb->state);
darran	0:ac21159e27f4	260	#endif /* TCP_DEBUG */
darran	0:ac21159e27f4	261	#endif /* TCP_INPUT_DEBUG */
darran	0:ac21159e27f4	262
darran	0:ac21159e27f4	263	/* Set up a tcp_seg structure. */
darran	0:ac21159e27f4	264	inseg.next = NULL;
darran	0:ac21159e27f4	265	inseg.len = p->tot_len;
darran	0:ac21159e27f4	266	inseg.dataptr = p->payload;
darran	0:ac21159e27f4	267	inseg.p = p;
darran	0:ac21159e27f4	268	inseg.tcphdr = tcphdr;
darran	0:ac21159e27f4	269
darran	0:ac21159e27f4	270	recv_data = NULL;
darran	0:ac21159e27f4	271	recv_flags = 0;
darran	0:ac21159e27f4	272
darran	0:ac21159e27f4	273	/* If there is data which was previously "refused" by upper layer */
darran	0:ac21159e27f4	274	if (pcb->refused_data != NULL) {
darran	0:ac21159e27f4	275	/* Notify again application with data previously received. */
darran	0:ac21159e27f4	276	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
darran	0:ac21159e27f4	277	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
darran	0:ac21159e27f4	278	if (err == ERR_OK) {
darran	0:ac21159e27f4	279	pcb->refused_data = NULL;
darran	0:ac21159e27f4	280	} else {
darran	0:ac21159e27f4	281	/* if err == ERR_ABRT, 'pcb' is already deallocated */
darran	0:ac21159e27f4	282	/* drop incoming packets, because pcb is "full" */
darran	0:ac21159e27f4	283	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
darran	0:ac21159e27f4	284	TCP_STATS_INC(tcp.drop);
darran	0:ac21159e27f4	285	snmp_inc_tcpinerrs();
darran	0:ac21159e27f4	286	pbuf_free(p);
darran	0:ac21159e27f4	287	return;
darran	0:ac21159e27f4	288	}
darran	0:ac21159e27f4	289	}
darran	0:ac21159e27f4	290	tcp_input_pcb = pcb;
darran	0:ac21159e27f4	291	err = tcp_process(pcb);
darran	0:ac21159e27f4	292	/* A return value of ERR_ABRT means that tcp_abort() was called
darran	0:ac21159e27f4	293	and that the pcb has been freed. If so, we don't do anything. */
darran	0:ac21159e27f4	294	if (err != ERR_ABRT) {
darran	0:ac21159e27f4	295	if (recv_flags & TF_RESET) {
darran	0:ac21159e27f4	296	/* TF_RESET means that the connection was reset by the other
darran	0:ac21159e27f4	297	end. We then call the error callback to inform the
darran	0:ac21159e27f4	298	application that the connection is dead before we
darran	0:ac21159e27f4	299	deallocate the PCB. */
darran	0:ac21159e27f4	300	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
darran	0:ac21159e27f4	301	tcp_pcb_remove(&tcp_active_pcbs, pcb);
darran	0:ac21159e27f4	302	memp_free(MEMP_TCP_PCB, pcb);
darran	0:ac21159e27f4	303	} else if (recv_flags & TF_CLOSED) {
darran	0:ac21159e27f4	304	/* The connection has been closed and we will deallocate the
darran	0:ac21159e27f4	305	PCB. */
darran	0:ac21159e27f4	306	tcp_pcb_remove(&tcp_active_pcbs, pcb);
darran	0:ac21159e27f4	307	memp_free(MEMP_TCP_PCB, pcb);
darran	0:ac21159e27f4	308	} else {
darran	0:ac21159e27f4	309	err = ERR_OK;
darran	0:ac21159e27f4	310	/* If the application has registered a "sent" function to be
darran	0:ac21159e27f4	311	called when new send buffer space is available, we call it
darran	0:ac21159e27f4	312	now. */
darran	0:ac21159e27f4	313	if (pcb->acked > 0) {
darran	0:ac21159e27f4	314	TCP_EVENT_SENT(pcb, pcb->acked, err);
darran	0:ac21159e27f4	315	if (err == ERR_ABRT) {
darran	0:ac21159e27f4	316	goto aborted;
darran	0:ac21159e27f4	317	}
darran	0:ac21159e27f4	318	}
darran	0:ac21159e27f4	319
darran	0:ac21159e27f4	320	if (recv_data != NULL) {
darran	0:ac21159e27f4	321	if(flags & TCP_PSH) {
darran	0:ac21159e27f4	322	recv_data->flags \|= PBUF_FLAG_PUSH;
darran	0:ac21159e27f4	323	}
darran	0:ac21159e27f4	324
darran	0:ac21159e27f4	325	/* Notify application that data has been received. */
darran	0:ac21159e27f4	326	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
darran	0:ac21159e27f4	327	if (err == ERR_ABRT) {
darran	0:ac21159e27f4	328	goto aborted;
darran	0:ac21159e27f4	329	}
darran	0:ac21159e27f4	330
darran	0:ac21159e27f4	331	/* If the upper layer can't receive this data, store it */
darran	0:ac21159e27f4	332	if (err != ERR_OK) {
darran	0:ac21159e27f4	333	pcb->refused_data = recv_data;
darran	0:ac21159e27f4	334	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
darran	0:ac21159e27f4	335	}
darran	0:ac21159e27f4	336	}
darran	0:ac21159e27f4	337
darran	0:ac21159e27f4	338	/* If a FIN segment was received, we call the callback
darran	0:ac21159e27f4	339	function with a NULL buffer to indicate EOF. */
darran	0:ac21159e27f4	340	if (recv_flags & TF_GOT_FIN) {
darran	0:ac21159e27f4	341	/* correct rcv_wnd as the application won't call tcp_recved()
darran	0:ac21159e27f4	342	for the FIN's seqno */
darran	0:ac21159e27f4	343	if (pcb->rcv_wnd != TCP_WND) {
darran	0:ac21159e27f4	344	pcb->rcv_wnd++;
darran	0:ac21159e27f4	345	}
darran	0:ac21159e27f4	346	TCP_EVENT_RECV(pcb, NULL, ERR_OK, err);
darran	0:ac21159e27f4	347	if (err == ERR_ABRT) {
darran	0:ac21159e27f4	348	goto aborted;
darran	0:ac21159e27f4	349	}
darran	0:ac21159e27f4	350	}
darran	0:ac21159e27f4	351
darran	0:ac21159e27f4	352	tcp_input_pcb = NULL;
darran	0:ac21159e27f4	353	/* Try to send something out. */
darran	0:ac21159e27f4	354	tcp_output(pcb);
darran	0:ac21159e27f4	355	#if TCP_INPUT_DEBUG
darran	0:ac21159e27f4	356	#if TCP_DEBUG
darran	0:ac21159e27f4	357	tcp_debug_print_state(pcb->state);
darran	0:ac21159e27f4	358	#endif /* TCP_DEBUG */
darran	0:ac21159e27f4	359	#endif /* TCP_INPUT_DEBUG */
darran	0:ac21159e27f4	360	}
darran	0:ac21159e27f4	361	}
darran	0:ac21159e27f4	362	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
darran	0:ac21159e27f4	363	Below this line, 'pcb' may not be dereferenced! */
darran	0:ac21159e27f4	364	aborted:
darran	0:ac21159e27f4	365	tcp_input_pcb = NULL;
darran	0:ac21159e27f4	366
darran	0:ac21159e27f4	367
darran	0:ac21159e27f4	368	/* give up our reference to inseg.p */
darran	0:ac21159e27f4	369	if (inseg.p != NULL)
darran	0:ac21159e27f4	370	{
darran	0:ac21159e27f4	371	pbuf_free(inseg.p);
darran	0:ac21159e27f4	372	inseg.p = NULL;
darran	0:ac21159e27f4	373	}
darran	0:ac21159e27f4	374	} else {
darran	0:ac21159e27f4	375
darran	0:ac21159e27f4	376	/* If no matching PCB was found, send a TCP RST (reset) to the
darran	0:ac21159e27f4	377	sender. */
darran	0:ac21159e27f4	378	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
darran	0:ac21159e27f4	379	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
darran	0:ac21159e27f4	380	TCP_STATS_INC(tcp.proterr);
darran	0:ac21159e27f4	381	TCP_STATS_INC(tcp.drop);
darran	0:ac21159e27f4	382	tcp_rst(ackno, seqno + tcplen,
darran	0:ac21159e27f4	383	&(iphdr->dest), &(iphdr->src),
darran	0:ac21159e27f4	384	tcphdr->dest, tcphdr->src);
darran	0:ac21159e27f4	385	}
darran	0:ac21159e27f4	386	pbuf_free(p);
darran	0:ac21159e27f4	387	}
darran	0:ac21159e27f4	388
darran	0:ac21159e27f4	389	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
darran	0:ac21159e27f4	390	PERF_STOP("tcp_input");
darran	0:ac21159e27f4	391	}
darran	0:ac21159e27f4	392
darran	0:ac21159e27f4	393	/**
darran	0:ac21159e27f4	394	* Called by tcp_input() when a segment arrives for a listening
darran	0:ac21159e27f4	395	* connection (from tcp_input()).
darran	0:ac21159e27f4	396	*
darran	0:ac21159e27f4	397	* @param pcb the tcp_pcb_listen for which a segment arrived
darran	0:ac21159e27f4	398	* @return ERR_OK if the segment was processed
darran	0:ac21159e27f4	399	* another err_t on error
darran	0:ac21159e27f4	400	*
darran	0:ac21159e27f4	401	* @note the return value is not (yet?) used in tcp_input()
darran	0:ac21159e27f4	402	* @note the segment which arrived is saved in global variables, therefore only the pcb
darran	0:ac21159e27f4	403	* involved is passed as a parameter to this function
darran	0:ac21159e27f4	404	*/
darran	0:ac21159e27f4	405	static err_t
darran	0:ac21159e27f4	406	tcp_listen_input(struct tcp_pcb_listen *pcb)
darran	0:ac21159e27f4	407	{
darran	0:ac21159e27f4	408	struct tcp_pcb *npcb;
darran	0:ac21159e27f4	409	err_t rc;
darran	0:ac21159e27f4	410
darran	0:ac21159e27f4	411	/* In the LISTEN state, we check for incoming SYN segments,
darran	0:ac21159e27f4	412	creates a new PCB, and responds with a SYN\|ACK. */
darran	0:ac21159e27f4	413	if (flags & TCP_ACK) {
darran	0:ac21159e27f4	414	/* For incoming segments with the ACK flag set, respond with a
darran	0:ac21159e27f4	415	RST. */
darran	0:ac21159e27f4	416	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
darran	0:ac21159e27f4	417	tcp_rst(ackno + 1, seqno + tcplen,
darran	0:ac21159e27f4	418	&(iphdr->dest), &(iphdr->src),
darran	0:ac21159e27f4	419	tcphdr->dest, tcphdr->src);
darran	0:ac21159e27f4	420	} else if (flags & TCP_SYN) {
darran	0:ac21159e27f4	421	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
darran	0:ac21159e27f4	422	#if TCP_LISTEN_BACKLOG
darran	0:ac21159e27f4	423	if (pcb->accepts_pending >= pcb->backlog) {
darran	0:ac21159e27f4	424	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
darran	0:ac21159e27f4	425	return ERR_ABRT;
darran	0:ac21159e27f4	426	}
darran	0:ac21159e27f4	427	#endif /* TCP_LISTEN_BACKLOG */
darran	0:ac21159e27f4	428	npcb = tcp_alloc(pcb->prio);
darran	0:ac21159e27f4	429	/* If a new PCB could not be created (probably due to lack of memory),
darran	0:ac21159e27f4	430	we don't do anything, but rely on the sender will retransmit the
darran	0:ac21159e27f4	431	SYN at a time when we have more memory available. */
darran	0:ac21159e27f4	432	if (npcb == NULL) {
darran	0:ac21159e27f4	433	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
darran	0:ac21159e27f4	434	TCP_STATS_INC(tcp.memerr);
darran	0:ac21159e27f4	435	return ERR_MEM;
darran	0:ac21159e27f4	436	}
darran	0:ac21159e27f4	437	#if TCP_LISTEN_BACKLOG
darran	0:ac21159e27f4	438	pcb->accepts_pending++;
darran	0:ac21159e27f4	439	#endif /* TCP_LISTEN_BACKLOG */
darran	0:ac21159e27f4	440	/* Set up the new PCB. */
darran	0:ac21159e27f4	441	ip_addr_copy(npcb->local_ip, iphdr->dest);
darran	0:ac21159e27f4	442	npcb->local_port = pcb->local_port;
darran	0:ac21159e27f4	443	ip_addr_copy(npcb->remote_ip, iphdr->src);
darran	0:ac21159e27f4	444	npcb->remote_port = tcphdr->src;
darran	0:ac21159e27f4	445	npcb->state = SYN_RCVD;
darran	0:ac21159e27f4	446	npcb->rcv_nxt = seqno + 1;
darran	0:ac21159e27f4	447	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
darran	0:ac21159e27f4	448	npcb->snd_wnd = tcphdr->wnd;
darran	0:ac21159e27f4	449	npcb->ssthresh = npcb->snd_wnd;
darran	0:ac21159e27f4	450	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
darran	0:ac21159e27f4	451	npcb->callback_arg = pcb->callback_arg;
darran	0:ac21159e27f4	452	#if LWIP_CALLBACK_API
darran	0:ac21159e27f4	453	npcb->accept = pcb->accept;
darran	0:ac21159e27f4	454	#endif /* LWIP_CALLBACK_API */
darran	0:ac21159e27f4	455	/* inherit socket options */
darran	0:ac21159e27f4	456	npcb->so_options = pcb->so_options & (SOF_DEBUG\|SOF_DONTROUTE\|SOF_KEEPALIVE\|SOF_OOBINLINE\|SOF_LINGER);
darran	0:ac21159e27f4	457	/* Register the new PCB so that we can begin receiving segments
darran	0:ac21159e27f4	458	for it. */
darran	0:ac21159e27f4	459	TCP_REG(&tcp_active_pcbs, npcb);
darran	0:ac21159e27f4	460
darran	0:ac21159e27f4	461	/* Parse any options in the SYN. */
darran	0:ac21159e27f4	462	tcp_parseopt(npcb);
darran	0:ac21159e27f4	463	#if TCP_CALCULATE_EFF_SEND_MSS
darran	0:ac21159e27f4	464	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
darran	0:ac21159e27f4	465	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
darran	0:ac21159e27f4	466
darran	0:ac21159e27f4	467	snmp_inc_tcppassiveopens();
darran	0:ac21159e27f4	468
darran	0:ac21159e27f4	469	/* Send a SYN\|ACK together with the MSS option. */
darran	0:ac21159e27f4	470	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
darran	0:ac21159e27f4	471	if (rc != ERR_OK) {
darran	0:ac21159e27f4	472	tcp_abandon(npcb, 0);
darran	0:ac21159e27f4	473	return rc;
darran	0:ac21159e27f4	474	}
darran	0:ac21159e27f4	475	return tcp_output(npcb);
darran	0:ac21159e27f4	476	}
darran	0:ac21159e27f4	477	return ERR_OK;
darran	0:ac21159e27f4	478	}
darran	0:ac21159e27f4	479
darran	0:ac21159e27f4	480	/**
darran	0:ac21159e27f4	481	* Called by tcp_input() when a segment arrives for a connection in
darran	0:ac21159e27f4	482	* TIME_WAIT.
darran	0:ac21159e27f4	483	*
darran	0:ac21159e27f4	484	* @param pcb the tcp_pcb for which a segment arrived
darran	0:ac21159e27f4	485	*
darran	0:ac21159e27f4	486	* @note the segment which arrived is saved in global variables, therefore only the pcb
darran	0:ac21159e27f4	487	* involved is passed as a parameter to this function
darran	0:ac21159e27f4	488	*/
darran	0:ac21159e27f4	489	static err_t
darran	0:ac21159e27f4	490	tcp_timewait_input(struct tcp_pcb *pcb)
darran	0:ac21159e27f4	491	{
darran	0:ac21159e27f4	492	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
darran	0:ac21159e27f4	493	/* RFC 793 3.9 Event Processing - Segment Arrives:
darran	0:ac21159e27f4	494	* - first check sequence number - we skip that one in TIME_WAIT (always
darran	0:ac21159e27f4	495	* acceptable since we only send ACKs)
darran	0:ac21159e27f4	496	* - second check the RST bit (... return) */
darran	0:ac21159e27f4	497	if (flags & TCP_RST) {
darran	0:ac21159e27f4	498	return ERR_OK;
darran	0:ac21159e27f4	499	}
darran	0:ac21159e27f4	500	/* - fourth, check the SYN bit, */
darran	0:ac21159e27f4	501	if (flags & TCP_SYN) {
darran	0:ac21159e27f4	502	/* If an incoming segment is not acceptable, an acknowledgment
darran	0:ac21159e27f4	503	should be sent in reply */
darran	0:ac21159e27f4	504	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
darran	0:ac21159e27f4	505	/* If the SYN is in the window it is an error, send a reset */
darran	0:ac21159e27f4	506	tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
darran	0:ac21159e27f4	507	tcphdr->dest, tcphdr->src);
darran	0:ac21159e27f4	508	return ERR_OK;
darran	0:ac21159e27f4	509	}
darran	0:ac21159e27f4	510	} else if (flags & TCP_FIN) {
darran	0:ac21159e27f4	511	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
darran	0:ac21159e27f4	512	Restart the 2 MSL time-wait timeout.*/
darran	0:ac21159e27f4	513	pcb->tmr = tcp_ticks;
darran	0:ac21159e27f4	514	}
darran	0:ac21159e27f4	515
darran	0:ac21159e27f4	516	if ((tcplen > 0)) {
darran	0:ac21159e27f4	517	/* Acknowledge data, FIN or out-of-window SYN */
darran	0:ac21159e27f4	518	pcb->flags \|= TF_ACK_NOW;
darran	0:ac21159e27f4	519	return tcp_output(pcb);
darran	0:ac21159e27f4	520	}
darran	0:ac21159e27f4	521	return ERR_OK;
darran	0:ac21159e27f4	522	}
darran	0:ac21159e27f4	523
darran	0:ac21159e27f4	524	/**
darran	0:ac21159e27f4	525	* Implements the TCP state machine. Called by tcp_input. In some
darran	0:ac21159e27f4	526	* states tcp_receive() is called to receive data. The tcp_seg
darran	0:ac21159e27f4	527	* argument will be freed by the caller (tcp_input()) unless the
darran	0:ac21159e27f4	528	* recv_data pointer in the pcb is set.
darran	0:ac21159e27f4	529	*
darran	0:ac21159e27f4	530	* @param pcb the tcp_pcb for which a segment arrived
darran	0:ac21159e27f4	531	*
darran	0:ac21159e27f4	532	* @note the segment which arrived is saved in global variables, therefore only the pcb
darran	0:ac21159e27f4	533	* involved is passed as a parameter to this function
darran	0:ac21159e27f4	534	*/
darran	0:ac21159e27f4	535	static err_t
darran	0:ac21159e27f4	536	tcp_process(struct tcp_pcb *pcb)
darran	0:ac21159e27f4	537	{
darran	0:ac21159e27f4	538	struct tcp_seg *rseg;
darran	0:ac21159e27f4	539	u8_t acceptable = 0;
darran	0:ac21159e27f4	540	err_t err;
darran	0:ac21159e27f4	541
darran	0:ac21159e27f4	542	err = ERR_OK;
darran	0:ac21159e27f4	543
darran	0:ac21159e27f4	544	/* Process incoming RST segments. */
darran	0:ac21159e27f4	545	if (flags & TCP_RST) {
darran	0:ac21159e27f4	546	/* First, determine if the reset is acceptable. */
darran	0:ac21159e27f4	547	if (pcb->state == SYN_SENT) {
darran	0:ac21159e27f4	548	if (ackno == pcb->snd_nxt) {
darran	0:ac21159e27f4	549	acceptable = 1;
darran	0:ac21159e27f4	550	}
darran	0:ac21159e27f4	551	} else {
darran	0:ac21159e27f4	552	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
darran	0:ac21159e27f4	553	pcb->rcv_nxt+pcb->rcv_wnd)) {
darran	0:ac21159e27f4	554	acceptable = 1;
darran	0:ac21159e27f4	555	}
darran	0:ac21159e27f4	556	}
darran	0:ac21159e27f4	557
darran	0:ac21159e27f4	558	if (acceptable) {
darran	0:ac21159e27f4	559	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
darran	0:ac21159e27f4	560	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
darran	0:ac21159e27f4	561	recv_flags \|= TF_RESET;
darran	0:ac21159e27f4	562	pcb->flags &= ~TF_ACK_DELAY;
darran	0:ac21159e27f4	563	return ERR_RST;
darran	0:ac21159e27f4	564	} else {
darran	0:ac21159e27f4	565	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
darran	0:ac21159e27f4	566	seqno, pcb->rcv_nxt));
darran	0:ac21159e27f4	567	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
darran	0:ac21159e27f4	568	seqno, pcb->rcv_nxt));
darran	0:ac21159e27f4	569	return ERR_OK;
darran	0:ac21159e27f4	570	}
darran	0:ac21159e27f4	571	}
darran	0:ac21159e27f4	572
darran	0:ac21159e27f4	573	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
darran	0:ac21159e27f4	574	/* Cope with new connection attempt after remote end crashed */
darran	0:ac21159e27f4	575	tcp_ack_now(pcb);
darran	0:ac21159e27f4	576	return ERR_OK;
darran	0:ac21159e27f4	577	}
darran	0:ac21159e27f4	578
darran	0:ac21159e27f4	579	if ((pcb->flags & TF_RXCLOSED) == 0) {
darran	0:ac21159e27f4	580	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
darran	0:ac21159e27f4	581	pcb->tmr = tcp_ticks;
darran	0:ac21159e27f4	582	}
darran	0:ac21159e27f4	583	pcb->keep_cnt_sent = 0;
darran	0:ac21159e27f4	584
darran	0:ac21159e27f4	585	tcp_parseopt(pcb);
darran	0:ac21159e27f4	586
darran	0:ac21159e27f4	587	/* Do different things depending on the TCP state. */
darran	0:ac21159e27f4	588	switch (pcb->state) {
darran	0:ac21159e27f4	589	case SYN_SENT:
darran	0:ac21159e27f4	590	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
darran	0:ac21159e27f4	591	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
darran	0:ac21159e27f4	592	/* received SYN ACK with expected sequence number? */
darran	0:ac21159e27f4	593	if ((flags & TCP_ACK) && (flags & TCP_SYN)
darran	0:ac21159e27f4	594	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
darran	0:ac21159e27f4	595	pcb->snd_buf++;
darran	0:ac21159e27f4	596	pcb->rcv_nxt = seqno + 1;
darran	0:ac21159e27f4	597	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
darran	0:ac21159e27f4	598	pcb->lastack = ackno;
darran	0:ac21159e27f4	599	pcb->snd_wnd = tcphdr->wnd;
darran	0:ac21159e27f4	600	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
darran	0:ac21159e27f4	601	pcb->state = ESTABLISHED;
darran	0:ac21159e27f4	602
darran	0:ac21159e27f4	603	#if TCP_CALCULATE_EFF_SEND_MSS
darran	0:ac21159e27f4	604	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
darran	0:ac21159e27f4	605	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
darran	0:ac21159e27f4	606
darran	0:ac21159e27f4	607	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
darran	0:ac21159e27f4	608	* but for the default value of pcb->mss) */
darran	0:ac21159e27f4	609	pcb->ssthresh = pcb->mss * 10;
darran	0:ac21159e27f4	610
darran	0:ac21159e27f4	611	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
darran	0:ac21159e27f4	612	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
darran	0:ac21159e27f4	613	--pcb->snd_queuelen;
darran	0:ac21159e27f4	614	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
darran	0:ac21159e27f4	615	rseg = pcb->unacked;
darran	0:ac21159e27f4	616	pcb->unacked = rseg->next;
darran	0:ac21159e27f4	617
darran	0:ac21159e27f4	618	/* If there's nothing left to acknowledge, stop the retransmit
darran	0:ac21159e27f4	619	timer, otherwise reset it to start again */
darran	0:ac21159e27f4	620	if(pcb->unacked == NULL)
darran	0:ac21159e27f4	621	pcb->rtime = -1;
darran	0:ac21159e27f4	622	else {
darran	0:ac21159e27f4	623	pcb->rtime = 0;
darran	0:ac21159e27f4	624	pcb->nrtx = 0;
darran	0:ac21159e27f4	625	}
darran	0:ac21159e27f4	626
darran	0:ac21159e27f4	627	tcp_seg_free(rseg);
darran	0:ac21159e27f4	628
darran	0:ac21159e27f4	629	/* Call the user specified function to call when sucessfully
darran	0:ac21159e27f4	630	* connected. */
darran	0:ac21159e27f4	631	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
darran	0:ac21159e27f4	632	if (err == ERR_ABRT) {
darran	0:ac21159e27f4	633	return ERR_ABRT;
darran	0:ac21159e27f4	634	}
darran	0:ac21159e27f4	635	tcp_ack_now(pcb);
darran	0:ac21159e27f4	636	}
darran	0:ac21159e27f4	637	/* received ACK? possibly a half-open connection */
darran	0:ac21159e27f4	638	else if (flags & TCP_ACK) {
darran	0:ac21159e27f4	639	/* send a RST to bring the other side in a non-synchronized state. */
darran	0:ac21159e27f4	640	tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
darran	0:ac21159e27f4	641	tcphdr->dest, tcphdr->src);
darran	0:ac21159e27f4	642	}
darran	0:ac21159e27f4	643	break;
darran	0:ac21159e27f4	644	case SYN_RCVD:
darran	0:ac21159e27f4	645	if (flags & TCP_ACK) {
darran	0:ac21159e27f4	646	/* expected ACK number? */
darran	0:ac21159e27f4	647	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
darran	0:ac21159e27f4	648	u16_t old_cwnd;
darran	0:ac21159e27f4	649	pcb->state = ESTABLISHED;
darran	0:ac21159e27f4	650	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
darran	0:ac21159e27f4	651	#if LWIP_CALLBACK_API
darran	0:ac21159e27f4	652	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
darran	0:ac21159e27f4	653	#endif
darran	0:ac21159e27f4	654	/* Call the accept function. */
darran	0:ac21159e27f4	655	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
darran	0:ac21159e27f4	656	if (err != ERR_OK) {
darran	0:ac21159e27f4	657	/* If the accept function returns with an error, we abort
darran	0:ac21159e27f4	658	* the connection. */
darran	0:ac21159e27f4	659	/* Already aborted? */
darran	0:ac21159e27f4	660	if (err != ERR_ABRT) {
darran	0:ac21159e27f4	661	tcp_abort(pcb);
darran	0:ac21159e27f4	662	}
darran	0:ac21159e27f4	663	return ERR_ABRT;
darran	0:ac21159e27f4	664	}
darran	0:ac21159e27f4	665	old_cwnd = pcb->cwnd;
darran	0:ac21159e27f4	666	/* If there was any data contained within this ACK,
darran	0:ac21159e27f4	667	* we'd better pass it on to the application as well. */
darran	0:ac21159e27f4	668	tcp_receive(pcb);
darran	0:ac21159e27f4	669
darran	0:ac21159e27f4	670	/* Prevent ACK for SYN to generate a sent event */
darran	0:ac21159e27f4	671	if (pcb->acked != 0) {
darran	0:ac21159e27f4	672	pcb->acked--;
darran	0:ac21159e27f4	673	}
darran	0:ac21159e27f4	674
darran	0:ac21159e27f4	675	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
darran	0:ac21159e27f4	676
darran	0:ac21159e27f4	677	if (recv_flags & TF_GOT_FIN) {
darran	0:ac21159e27f4	678	tcp_ack_now(pcb);
darran	0:ac21159e27f4	679	pcb->state = CLOSE_WAIT;
darran	0:ac21159e27f4	680	}
darran	0:ac21159e27f4	681	} else {
darran	0:ac21159e27f4	682	/* incorrect ACK number, send RST */
darran	0:ac21159e27f4	683	tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
darran	0:ac21159e27f4	684	tcphdr->dest, tcphdr->src);
darran	0:ac21159e27f4	685	}
darran	0:ac21159e27f4	686	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
darran	0:ac21159e27f4	687	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
darran	0:ac21159e27f4	688	tcp_rexmit(pcb);
darran	0:ac21159e27f4	689	}
darran	0:ac21159e27f4	690	break;
darran	0:ac21159e27f4	691	case CLOSE_WAIT:
darran	0:ac21159e27f4	692	/* FALLTHROUGH */
darran	0:ac21159e27f4	693	case ESTABLISHED:
darran	0:ac21159e27f4	694	tcp_receive(pcb);
darran	0:ac21159e27f4	695	if (recv_flags & TF_GOT_FIN) { /* passive close */
darran	0:ac21159e27f4	696	tcp_ack_now(pcb);
darran	0:ac21159e27f4	697	pcb->state = CLOSE_WAIT;
darran	0:ac21159e27f4	698	}
darran	0:ac21159e27f4	699	break;
darran	0:ac21159e27f4	700	case FIN_WAIT_1:
darran	0:ac21159e27f4	701	tcp_receive(pcb);
darran	0:ac21159e27f4	702	if (recv_flags & TF_GOT_FIN) {
darran	0:ac21159e27f4	703	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
darran	0:ac21159e27f4	704	LWIP_DEBUGF(TCP_DEBUG,
darran	0:ac21159e27f4	705	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
darran	0:ac21159e27f4	706	tcp_ack_now(pcb);
darran	0:ac21159e27f4	707	tcp_pcb_purge(pcb);
darran	0:ac21159e27f4	708	TCP_RMV(&tcp_active_pcbs, pcb);
darran	0:ac21159e27f4	709	pcb->state = TIME_WAIT;
darran	0:ac21159e27f4	710	TCP_REG(&tcp_tw_pcbs, pcb);
darran	0:ac21159e27f4	711	} else {
darran	0:ac21159e27f4	712	tcp_ack_now(pcb);
darran	0:ac21159e27f4	713	pcb->state = CLOSING;
darran	0:ac21159e27f4	714	}
darran	0:ac21159e27f4	715	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
darran	0:ac21159e27f4	716	pcb->state = FIN_WAIT_2;
darran	0:ac21159e27f4	717	}
darran	0:ac21159e27f4	718	break;
darran	0:ac21159e27f4	719	case FIN_WAIT_2:
darran	0:ac21159e27f4	720	tcp_receive(pcb);
darran	0:ac21159e27f4	721	if (recv_flags & TF_GOT_FIN) {
darran	0:ac21159e27f4	722	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
darran	0:ac21159e27f4	723	tcp_ack_now(pcb);
darran	0:ac21159e27f4	724	tcp_pcb_purge(pcb);
darran	0:ac21159e27f4	725	TCP_RMV(&tcp_active_pcbs, pcb);
darran	0:ac21159e27f4	726	pcb->state = TIME_WAIT;
darran	0:ac21159e27f4	727	TCP_REG(&tcp_tw_pcbs, pcb);
darran	0:ac21159e27f4	728	}
darran	0:ac21159e27f4	729	break;
darran	0:ac21159e27f4	730	case CLOSING:
darran	0:ac21159e27f4	731	tcp_receive(pcb);
darran	0:ac21159e27f4	732	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
darran	0:ac21159e27f4	733	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
darran	0:ac21159e27f4	734	tcp_pcb_purge(pcb);
darran	0:ac21159e27f4	735	TCP_RMV(&tcp_active_pcbs, pcb);
darran	0:ac21159e27f4	736	pcb->state = TIME_WAIT;
darran	0:ac21159e27f4	737	TCP_REG(&tcp_tw_pcbs, pcb);
darran	0:ac21159e27f4	738	}
darran	0:ac21159e27f4	739	break;
darran	0:ac21159e27f4	740	case LAST_ACK:
darran	0:ac21159e27f4	741	tcp_receive(pcb);
darran	0:ac21159e27f4	742	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
darran	0:ac21159e27f4	743	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
darran	0:ac21159e27f4	744	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
darran	0:ac21159e27f4	745	recv_flags \|= TF_CLOSED;
darran	0:ac21159e27f4	746	}
darran	0:ac21159e27f4	747	break;
darran	0:ac21159e27f4	748	default:
darran	0:ac21159e27f4	749	break;
darran	0:ac21159e27f4	750	}
darran	0:ac21159e27f4	751	return ERR_OK;
darran	0:ac21159e27f4	752	}
darran	0:ac21159e27f4	753
darran	0:ac21159e27f4	754	#if TCP_QUEUE_OOSEQ
darran	0:ac21159e27f4	755	/**
darran	0:ac21159e27f4	756	* Insert segment into the list (segments covered with new one will be deleted)
darran	0:ac21159e27f4	757	*
darran	0:ac21159e27f4	758	* Called from tcp_receive()
darran	0:ac21159e27f4	759	*/
darran	0:ac21159e27f4	760	static void
darran	0:ac21159e27f4	761	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
darran	0:ac21159e27f4	762	{
darran	0:ac21159e27f4	763	struct tcp_seg *old_seg;
darran	0:ac21159e27f4	764
darran	0:ac21159e27f4	765	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	766	/* received segment overlaps all following segments */
darran	0:ac21159e27f4	767	tcp_segs_free(next);
darran	0:ac21159e27f4	768	next = NULL;
darran	0:ac21159e27f4	769	}
darran	0:ac21159e27f4	770	else {
darran	0:ac21159e27f4	771	/* delete some following segments
darran	0:ac21159e27f4	772	oos queue may have segments with FIN flag */
darran	0:ac21159e27f4	773	while (next &&
darran	0:ac21159e27f4	774	TCP_SEQ_GEQ((seqno + cseg->len),
darran	0:ac21159e27f4	775	(next->tcphdr->seqno + next->len))) {
darran	0:ac21159e27f4	776	/* cseg with FIN already processed */
darran	0:ac21159e27f4	777	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	778	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
darran	0:ac21159e27f4	779	}
darran	0:ac21159e27f4	780	old_seg = next;
darran	0:ac21159e27f4	781	next = next->next;
darran	0:ac21159e27f4	782	tcp_seg_free(old_seg);
darran	0:ac21159e27f4	783	}
darran	0:ac21159e27f4	784	if (next &&
darran	0:ac21159e27f4	785	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
darran	0:ac21159e27f4	786	/* We need to trim the incoming segment. */
darran	0:ac21159e27f4	787	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
darran	0:ac21159e27f4	788	pbuf_realloc(cseg->p, cseg->len);
darran	0:ac21159e27f4	789	}
darran	0:ac21159e27f4	790	}
darran	0:ac21159e27f4	791	cseg->next = next;
darran	0:ac21159e27f4	792	}
darran	0:ac21159e27f4	793	#endif /* TCP_QUEUE_OOSEQ */
darran	0:ac21159e27f4	794
darran	0:ac21159e27f4	795	/**
darran	0:ac21159e27f4	796	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
darran	0:ac21159e27f4	797	* data, and if so frees the memory of the buffered data. Next, is places the
darran	0:ac21159e27f4	798	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
darran	0:ac21159e27f4	799	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
darran	0:ac21159e27f4	800	* i it has been removed from the buffer.
darran	0:ac21159e27f4	801	*
darran	0:ac21159e27f4	802	* If the incoming segment constitutes an ACK for a segment that was used for RTT
darran	0:ac21159e27f4	803	* estimation, the RTT is estimated here as well.
darran	0:ac21159e27f4	804	*
darran	0:ac21159e27f4	805	* Called from tcp_process().
darran	0:ac21159e27f4	806	*/
darran	0:ac21159e27f4	807	static void
darran	0:ac21159e27f4	808	tcp_receive(struct tcp_pcb *pcb)
darran	0:ac21159e27f4	809	{
darran	0:ac21159e27f4	810	struct tcp_seg *next;
darran	0:ac21159e27f4	811	#if TCP_QUEUE_OOSEQ
darran	0:ac21159e27f4	812	struct tcp_seg prev, cseg;
darran	0:ac21159e27f4	813	#endif /* TCP_QUEUE_OOSEQ */
darran	0:ac21159e27f4	814	struct pbuf *p;
darran	0:ac21159e27f4	815	s32_t off;
darran	0:ac21159e27f4	816	s16_t m;
darran	0:ac21159e27f4	817	u32_t right_wnd_edge;
darran	0:ac21159e27f4	818	u16_t new_tot_len;
darran	0:ac21159e27f4	819	int found_dupack = 0;
darran	0:ac21159e27f4	820
darran	0:ac21159e27f4	821	if (flags & TCP_ACK) {
darran	0:ac21159e27f4	822	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
darran	0:ac21159e27f4	823
darran	0:ac21159e27f4	824	/* Update window. */
darran	0:ac21159e27f4	825	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
darran	0:ac21159e27f4	826	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
darran	0:ac21159e27f4	827	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
darran	0:ac21159e27f4	828	pcb->snd_wnd = tcphdr->wnd;
darran	0:ac21159e27f4	829	pcb->snd_wl1 = seqno;
darran	0:ac21159e27f4	830	pcb->snd_wl2 = ackno;
darran	0:ac21159e27f4	831	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
darran	0:ac21159e27f4	832	pcb->persist_backoff = 0;
darran	0:ac21159e27f4	833	}
darran	0:ac21159e27f4	834	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
darran	0:ac21159e27f4	835	#if TCP_WND_DEBUG
darran	0:ac21159e27f4	836	} else {
darran	0:ac21159e27f4	837	if (pcb->snd_wnd != tcphdr->wnd) {
darran	0:ac21159e27f4	838	LWIP_DEBUGF(TCP_WND_DEBUG,
darran	0:ac21159e27f4	839	("tcp_receive: no window update lastack %"U32_F" ackno %"
darran	0:ac21159e27f4	840	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
darran	0:ac21159e27f4	841	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
darran	0:ac21159e27f4	842	}
darran	0:ac21159e27f4	843	#endif /* TCP_WND_DEBUG */
darran	0:ac21159e27f4	844	}
darran	0:ac21159e27f4	845
darran	0:ac21159e27f4	846	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
darran	0:ac21159e27f4	847	* duplicate ack if:
darran	0:ac21159e27f4	848	* 1) It doesn't ACK new data
darran	0:ac21159e27f4	849	* 2) length of received packet is zero (i.e. no payload)
darran	0:ac21159e27f4	850	* 3) the advertised window hasn't changed
darran	0:ac21159e27f4	851	* 4) There is outstanding unacknowledged data (retransmission timer running)
darran	0:ac21159e27f4	852	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
darran	0:ac21159e27f4	853	*
darran	0:ac21159e27f4	854	* If it passes all five, should process as a dupack:
darran	0:ac21159e27f4	855	* a) dupacks < 3: do nothing
darran	0:ac21159e27f4	856	* b) dupacks == 3: fast retransmit
darran	0:ac21159e27f4	857	* c) dupacks > 3: increase cwnd
darran	0:ac21159e27f4	858	*
darran	0:ac21159e27f4	859	* If it only passes 1-3, should reset dupack counter (and add to
darran	0:ac21159e27f4	860	* stats, which we don't do in lwIP)
darran	0:ac21159e27f4	861	*
darran	0:ac21159e27f4	862	* If it only passes 1, should reset dupack counter
darran	0:ac21159e27f4	863	*
darran	0:ac21159e27f4	864	*/
darran	0:ac21159e27f4	865
darran	0:ac21159e27f4	866	/* Clause 1 */
darran	0:ac21159e27f4	867	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
darran	0:ac21159e27f4	868	pcb->acked = 0;
darran	0:ac21159e27f4	869	/* Clause 2 */
darran	0:ac21159e27f4	870	if (tcplen == 0) {
darran	0:ac21159e27f4	871	/* Clause 3 */
darran	0:ac21159e27f4	872	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
darran	0:ac21159e27f4	873	/* Clause 4 */
darran	0:ac21159e27f4	874	if (pcb->rtime >= 0) {
darran	0:ac21159e27f4	875	/* Clause 5 */
darran	0:ac21159e27f4	876	if (pcb->lastack == ackno) {
darran	0:ac21159e27f4	877	found_dupack = 1;
darran	0:ac21159e27f4	878	if (pcb->dupacks + 1 > pcb->dupacks)
darran	0:ac21159e27f4	879	++pcb->dupacks;
darran	0:ac21159e27f4	880	if (pcb->dupacks > 3) {
darran	0:ac21159e27f4	881	/* Inflate the congestion window, but not if it means that
darran	0:ac21159e27f4	882	the value overflows. */
darran	0:ac21159e27f4	883	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
darran	0:ac21159e27f4	884	pcb->cwnd += pcb->mss;
darran	0:ac21159e27f4	885	}
darran	0:ac21159e27f4	886	} else if (pcb->dupacks == 3) {
darran	0:ac21159e27f4	887	/* Do fast retransmit */
darran	0:ac21159e27f4	888	tcp_rexmit_fast(pcb);
darran	0:ac21159e27f4	889	}
darran	0:ac21159e27f4	890	}
darran	0:ac21159e27f4	891	}
darran	0:ac21159e27f4	892	}
darran	0:ac21159e27f4	893	}
darran	0:ac21159e27f4	894	/* If Clause (1) or more is true, but not a duplicate ack, reset
darran	0:ac21159e27f4	895	* count of consecutive duplicate acks */
darran	0:ac21159e27f4	896	if (!found_dupack) {
darran	0:ac21159e27f4	897	pcb->dupacks = 0;
darran	0:ac21159e27f4	898	}
darran	0:ac21159e27f4	899	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
darran	0:ac21159e27f4	900	/* We come here when the ACK acknowledges new data. */
darran	0:ac21159e27f4	901
darran	0:ac21159e27f4	902	/* Reset the "IN Fast Retransmit" flag, since we are no longer
darran	0:ac21159e27f4	903	in fast retransmit. Also reset the congestion window to the
darran	0:ac21159e27f4	904	slow start threshold. */
darran	0:ac21159e27f4	905	if (pcb->flags & TF_INFR) {
darran	0:ac21159e27f4	906	pcb->flags &= ~TF_INFR;
darran	0:ac21159e27f4	907	pcb->cwnd = pcb->ssthresh;
darran	0:ac21159e27f4	908	}
darran	0:ac21159e27f4	909
darran	0:ac21159e27f4	910	/* Reset the number of retransmissions. */
darran	0:ac21159e27f4	911	pcb->nrtx = 0;
darran	0:ac21159e27f4	912
darran	0:ac21159e27f4	913	/* Reset the retransmission time-out. */
darran	0:ac21159e27f4	914	pcb->rto = (pcb->sa >> 3) + pcb->sv;
darran	0:ac21159e27f4	915
darran	0:ac21159e27f4	916	/* Update the send buffer space. Diff between the two can never exceed 64K? */
darran	0:ac21159e27f4	917	pcb->acked = (u16_t)(ackno - pcb->lastack);
darran	0:ac21159e27f4	918
darran	0:ac21159e27f4	919	pcb->snd_buf += pcb->acked;
darran	0:ac21159e27f4	920
darran	0:ac21159e27f4	921	/* Reset the fast retransmit variables. */
darran	0:ac21159e27f4	922	pcb->dupacks = 0;
darran	0:ac21159e27f4	923	pcb->lastack = ackno;
darran	0:ac21159e27f4	924
darran	0:ac21159e27f4	925	/* Update the congestion control variables (cwnd and
darran	0:ac21159e27f4	926	ssthresh). */
darran	0:ac21159e27f4	927	if (pcb->state >= ESTABLISHED) {
darran	0:ac21159e27f4	928	if (pcb->cwnd < pcb->ssthresh) {
darran	0:ac21159e27f4	929	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
darran	0:ac21159e27f4	930	pcb->cwnd += pcb->mss;
darran	0:ac21159e27f4	931	}
darran	0:ac21159e27f4	932	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
darran	0:ac21159e27f4	933	} else {
darran	0:ac21159e27f4	934	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
darran	0:ac21159e27f4	935	if (new_cwnd > pcb->cwnd) {
darran	0:ac21159e27f4	936	pcb->cwnd = new_cwnd;
darran	0:ac21159e27f4	937	}
darran	0:ac21159e27f4	938	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
darran	0:ac21159e27f4	939	}
darran	0:ac21159e27f4	940	}
darran	0:ac21159e27f4	941	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
darran	0:ac21159e27f4	942	ackno,
darran	0:ac21159e27f4	943	pcb->unacked != NULL?
darran	0:ac21159e27f4	944	ntohl(pcb->unacked->tcphdr->seqno): 0,
darran	0:ac21159e27f4	945	pcb->unacked != NULL?
darran	0:ac21159e27f4	946	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
darran	0:ac21159e27f4	947
darran	0:ac21159e27f4	948	/* Remove segment from the unacknowledged list if the incoming
darran	0:ac21159e27f4	949	ACK acknowlegdes them. */
darran	0:ac21159e27f4	950	while (pcb->unacked != NULL &&
darran	0:ac21159e27f4	951	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
darran	0:ac21159e27f4	952	TCP_TCPLEN(pcb->unacked), ackno)) {
darran	0:ac21159e27f4	953	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
darran	0:ac21159e27f4	954	ntohl(pcb->unacked->tcphdr->seqno),
darran	0:ac21159e27f4	955	ntohl(pcb->unacked->tcphdr->seqno) +
darran	0:ac21159e27f4	956	TCP_TCPLEN(pcb->unacked)));
darran	0:ac21159e27f4	957
darran	0:ac21159e27f4	958	next = pcb->unacked;
darran	0:ac21159e27f4	959	pcb->unacked = pcb->unacked->next;
darran	0:ac21159e27f4	960
darran	0:ac21159e27f4	961	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
darran	0:ac21159e27f4	962	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
darran	0:ac21159e27f4	963	/* Prevent ACK for FIN to generate a sent event */
darran	0:ac21159e27f4	964	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
darran	0:ac21159e27f4	965	pcb->acked--;
darran	0:ac21159e27f4	966	}
darran	0:ac21159e27f4	967
darran	0:ac21159e27f4	968	pcb->snd_queuelen -= pbuf_clen(next->p);
darran	0:ac21159e27f4	969	tcp_seg_free(next);
darran	0:ac21159e27f4	970
darran	0:ac21159e27f4	971	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
darran	0:ac21159e27f4	972	if (pcb->snd_queuelen != 0) {
darran	0:ac21159e27f4	973	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
darran	0:ac21159e27f4	974	pcb->unsent != NULL);
darran	0:ac21159e27f4	975	}
darran	0:ac21159e27f4	976	}
darran	0:ac21159e27f4	977
darran	0:ac21159e27f4	978	/* If there's nothing left to acknowledge, stop the retransmit
darran	0:ac21159e27f4	979	timer, otherwise reset it to start again */
darran	0:ac21159e27f4	980	if(pcb->unacked == NULL)
darran	0:ac21159e27f4	981	pcb->rtime = -1;
darran	0:ac21159e27f4	982	else
darran	0:ac21159e27f4	983	pcb->rtime = 0;
darran	0:ac21159e27f4	984
darran	0:ac21159e27f4	985	pcb->polltmr = 0;
darran	0:ac21159e27f4	986	} else {
darran	0:ac21159e27f4	987	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
darran	0:ac21159e27f4	988	pcb->acked = 0;
darran	0:ac21159e27f4	989	}
darran	0:ac21159e27f4	990
darran	0:ac21159e27f4	991	/* We go through the ->unsent list to see if any of the segments
darran	0:ac21159e27f4	992	on the list are acknowledged by the ACK. This may seem
darran	0:ac21159e27f4	993	strange since an "unsent" segment shouldn't be acked. The
darran	0:ac21159e27f4	994	rationale is that lwIP puts all outstanding segments on the
darran	0:ac21159e27f4	995	->unsent list after a retransmission, so these segments may
darran	0:ac21159e27f4	996	in fact have been sent once. */
darran	0:ac21159e27f4	997	while (pcb->unsent != NULL &&
darran	0:ac21159e27f4	998	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
darran	0:ac21159e27f4	999	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
darran	0:ac21159e27f4	1000	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
darran	0:ac21159e27f4	1001	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
darran	0:ac21159e27f4	1002	TCP_TCPLEN(pcb->unsent)));
darran	0:ac21159e27f4	1003
darran	0:ac21159e27f4	1004	next = pcb->unsent;
darran	0:ac21159e27f4	1005	pcb->unsent = pcb->unsent->next;
darran	0:ac21159e27f4	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
darran	0:ac21159e27f4	1007	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
darran	0:ac21159e27f4	1008	/* Prevent ACK for FIN to generate a sent event */
darran	0:ac21159e27f4	1009	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
darran	0:ac21159e27f4	1010	pcb->acked--;
darran	0:ac21159e27f4	1011	}
darran	0:ac21159e27f4	1012	pcb->snd_queuelen -= pbuf_clen(next->p);
darran	0:ac21159e27f4	1013	tcp_seg_free(next);
darran	0:ac21159e27f4	1014	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
darran	0:ac21159e27f4	1015	if (pcb->snd_queuelen != 0) {
darran	0:ac21159e27f4	1016	LWIP_ASSERT("tcp_receive: valid queue length",
darran	0:ac21159e27f4	1017	pcb->unacked != NULL \|\| pcb->unsent != NULL);
darran	0:ac21159e27f4	1018	}
darran	0:ac21159e27f4	1019	}
darran	0:ac21159e27f4	1020	/* End of ACK for new data processing. */
darran	0:ac21159e27f4	1021
darran	0:ac21159e27f4	1022	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
darran	0:ac21159e27f4	1023	pcb->rttest, pcb->rtseq, ackno));
darran	0:ac21159e27f4	1024
darran	0:ac21159e27f4	1025	/* RTT estimation calculations. This is done by checking if the
darran	0:ac21159e27f4	1026	incoming segment acknowledges the segment we use to take a
darran	0:ac21159e27f4	1027	round-trip time measurement. */
darran	0:ac21159e27f4	1028	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
darran	0:ac21159e27f4	1029	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
darran	0:ac21159e27f4	1030	and a round-trip shouldn't be that long... */
darran	0:ac21159e27f4	1031	m = (s16_t)(tcp_ticks - pcb->rttest);
darran	0:ac21159e27f4	1032
darran	0:ac21159e27f4	1033	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
darran	0:ac21159e27f4	1034	m, m * TCP_SLOW_INTERVAL));
darran	0:ac21159e27f4	1035
darran	0:ac21159e27f4	1036	/* This is taken directly from VJs original code in his paper */
darran	0:ac21159e27f4	1037	m = m - (pcb->sa >> 3);
darran	0:ac21159e27f4	1038	pcb->sa += m;
darran	0:ac21159e27f4	1039	if (m < 0) {
darran	0:ac21159e27f4	1040	m = -m;
darran	0:ac21159e27f4	1041	}
darran	0:ac21159e27f4	1042	m = m - (pcb->sv >> 2);
darran	0:ac21159e27f4	1043	pcb->sv += m;
darran	0:ac21159e27f4	1044	pcb->rto = (pcb->sa >> 3) + pcb->sv;
darran	0:ac21159e27f4	1045
darran	0:ac21159e27f4	1046	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
darran	0:ac21159e27f4	1047	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
darran	0:ac21159e27f4	1048
darran	0:ac21159e27f4	1049	pcb->rttest = 0;
darran	0:ac21159e27f4	1050	}
darran	0:ac21159e27f4	1051	}
darran	0:ac21159e27f4	1052
darran	0:ac21159e27f4	1053	/* If the incoming segment contains data, we must process it
darran	0:ac21159e27f4	1054	further. */
darran	0:ac21159e27f4	1055	if (tcplen > 0) {
darran	0:ac21159e27f4	1056	/* This code basically does three things:
darran	0:ac21159e27f4	1057
darran	0:ac21159e27f4	1058	+) If the incoming segment contains data that is the next
darran	0:ac21159e27f4	1059	in-sequence data, this data is passed to the application. This
darran	0:ac21159e27f4	1060	might involve trimming the first edge of the data. The rcv_nxt
darran	0:ac21159e27f4	1061	variable and the advertised window are adjusted.
darran	0:ac21159e27f4	1062
darran	0:ac21159e27f4	1063	+) If the incoming segment has data that is above the next
darran	0:ac21159e27f4	1064	sequence number expected (->rcv_nxt), the segment is placed on
darran	0:ac21159e27f4	1065	the ->ooseq queue. This is done by finding the appropriate
darran	0:ac21159e27f4	1066	place in the ->ooseq queue (which is ordered by sequence
darran	0:ac21159e27f4	1067	number) and trim the segment in both ends if needed. An
darran	0:ac21159e27f4	1068	immediate ACK is sent to indicate that we received an
darran	0:ac21159e27f4	1069	out-of-sequence segment.
darran	0:ac21159e27f4	1070
darran	0:ac21159e27f4	1071	+) Finally, we check if the first segment on the ->ooseq queue
darran	0:ac21159e27f4	1072	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
darran	0:ac21159e27f4	1073	rcv_nxt > ooseq->seqno, we must trim the first edge of the
darran	0:ac21159e27f4	1074	segment on ->ooseq before we adjust rcv_nxt. The data in the
darran	0:ac21159e27f4	1075	segments that are now on sequence are chained onto the
darran	0:ac21159e27f4	1076	incoming segment so that we only need to call the application
darran	0:ac21159e27f4	1077	once.
darran	0:ac21159e27f4	1078	*/
darran	0:ac21159e27f4	1079
darran	0:ac21159e27f4	1080	/* First, we check if we must trim the first edge. We have to do
darran	0:ac21159e27f4	1081	this if the sequence number of the incoming segment is less
darran	0:ac21159e27f4	1082	than rcv_nxt, and the sequence number plus the length of the
darran	0:ac21159e27f4	1083	segment is larger than rcv_nxt. */
darran	0:ac21159e27f4	1084	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
darran	0:ac21159e27f4	1085	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
darran	0:ac21159e27f4	1086	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
darran	0:ac21159e27f4	1087	/* Trimming the first edge is done by pushing the payload
darran	0:ac21159e27f4	1088	pointer in the pbuf downwards. This is somewhat tricky since
darran	0:ac21159e27f4	1089	we do not want to discard the full contents of the pbuf up to
darran	0:ac21159e27f4	1090	the new starting point of the data since we have to keep the
darran	0:ac21159e27f4	1091	TCP header which is present in the first pbuf in the chain.
darran	0:ac21159e27f4	1092
darran	0:ac21159e27f4	1093	What is done is really quite a nasty hack: the first pbuf in
darran	0:ac21159e27f4	1094	the pbuf chain is pointed to by inseg.p. Since we need to be
darran	0:ac21159e27f4	1095	able to deallocate the whole pbuf, we cannot change this
darran	0:ac21159e27f4	1096	inseg.p pointer to point to any of the later pbufs in the
darran	0:ac21159e27f4	1097	chain. Instead, we point the ->payload pointer in the first
darran	0:ac21159e27f4	1098	pbuf to data in one of the later pbufs. We also set the
darran	0:ac21159e27f4	1099	inseg.data pointer to point to the right place. This way, the
darran	0:ac21159e27f4	1100	->p pointer will still point to the first pbuf, but the
darran	0:ac21159e27f4	1101	->p->payload pointer will point to data in another pbuf.
darran	0:ac21159e27f4	1102
darran	0:ac21159e27f4	1103	After we are done with adjusting the pbuf pointers we must
darran	0:ac21159e27f4	1104	adjust the ->data pointer in the seg and the segment
darran	0:ac21159e27f4	1105	length.*/
darran	0:ac21159e27f4	1106
darran	0:ac21159e27f4	1107	off = pcb->rcv_nxt - seqno;
darran	0:ac21159e27f4	1108	p = inseg.p;
darran	0:ac21159e27f4	1109	LWIP_ASSERT("inseg.p != NULL", inseg.p);
darran	0:ac21159e27f4	1110	LWIP_ASSERT("insane offset!", (off < 0x7fff));
darran	0:ac21159e27f4	1111	if (inseg.p->len < off) {
darran	0:ac21159e27f4	1112	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
darran	0:ac21159e27f4	1113	new_tot_len = (u16_t)(inseg.p->tot_len - off);
darran	0:ac21159e27f4	1114	while (p->len < off) {
darran	0:ac21159e27f4	1115	off -= p->len;
darran	0:ac21159e27f4	1116	/* KJM following line changed (with addition of new_tot_len var)
darran	0:ac21159e27f4	1117	to fix bug #9076
darran	0:ac21159e27f4	1118	inseg.p->tot_len -= p->len; */
darran	0:ac21159e27f4	1119	p->tot_len = new_tot_len;
darran	0:ac21159e27f4	1120	p->len = 0;
darran	0:ac21159e27f4	1121	p = p->next;
darran	0:ac21159e27f4	1122	}
darran	0:ac21159e27f4	1123	if(pbuf_header(p, (s16_t)-off)) {
darran	0:ac21159e27f4	1124	/* Do we need to cope with this failing? Assert for now */
darran	0:ac21159e27f4	1125	LWIP_ASSERT("pbuf_header failed", 0);
darran	0:ac21159e27f4	1126	}
darran	0:ac21159e27f4	1127	} else {
darran	0:ac21159e27f4	1128	if(pbuf_header(inseg.p, (s16_t)-off)) {
darran	0:ac21159e27f4	1129	/* Do we need to cope with this failing? Assert for now */
darran	0:ac21159e27f4	1130	LWIP_ASSERT("pbuf_header failed", 0);
darran	0:ac21159e27f4	1131	}
darran	0:ac21159e27f4	1132	}
darran	0:ac21159e27f4	1133	/* KJM following line changed to use p->payload rather than inseg->p->payload
darran	0:ac21159e27f4	1134	to fix bug #9076 */
darran	0:ac21159e27f4	1135	inseg.dataptr = p->payload;
darran	0:ac21159e27f4	1136	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
darran	0:ac21159e27f4	1137	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
darran	0:ac21159e27f4	1138	}
darran	0:ac21159e27f4	1139	else {
darran	0:ac21159e27f4	1140	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
darran	0:ac21159e27f4	1141	/* the whole segment is < rcv_nxt */
darran	0:ac21159e27f4	1142	/* must be a duplicate of a packet that has already been correctly handled */
darran	0:ac21159e27f4	1143
darran	0:ac21159e27f4	1144	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
darran	0:ac21159e27f4	1145	tcp_ack_now(pcb);
darran	0:ac21159e27f4	1146	}
darran	0:ac21159e27f4	1147	}
darran	0:ac21159e27f4	1148
darran	0:ac21159e27f4	1149	/* The sequence number must be within the window (above rcv_nxt
darran	0:ac21159e27f4	1150	and below rcv_nxt + rcv_wnd) in order to be further
darran	0:ac21159e27f4	1151	processed. */
darran	0:ac21159e27f4	1152	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
darran	0:ac21159e27f4	1153	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
darran	0:ac21159e27f4	1154	if (pcb->rcv_nxt == seqno) {
darran	0:ac21159e27f4	1155	/* The incoming segment is the next in sequence. We check if
darran	0:ac21159e27f4	1156	we have to trim the end of the segment and update rcv_nxt
darran	0:ac21159e27f4	1157	and pass the data to the application. */
darran	0:ac21159e27f4	1158	tcplen = TCP_TCPLEN(&inseg);
darran	0:ac21159e27f4	1159
darran	0:ac21159e27f4	1160	if (tcplen > pcb->rcv_wnd) {
darran	0:ac21159e27f4	1161	LWIP_DEBUGF(TCP_INPUT_DEBUG,
darran	0:ac21159e27f4	1162	("tcp_receive: other end overran receive window"
darran	0:ac21159e27f4	1163	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
darran	0:ac21159e27f4	1164	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
darran	0:ac21159e27f4	1165	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	1166	/* Must remove the FIN from the header as we're trimming
darran	0:ac21159e27f4	1167	* that byte of sequence-space from the packet */
darran	0:ac21159e27f4	1168	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
darran	0:ac21159e27f4	1169	}
darran	0:ac21159e27f4	1170	/* Adjust length of segment to fit in the window. */
darran	0:ac21159e27f4	1171	inseg.len = pcb->rcv_wnd;
darran	0:ac21159e27f4	1172	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
darran	0:ac21159e27f4	1173	inseg.len -= 1;
darran	0:ac21159e27f4	1174	}
darran	0:ac21159e27f4	1175	pbuf_realloc(inseg.p, inseg.len);
darran	0:ac21159e27f4	1176	tcplen = TCP_TCPLEN(&inseg);
darran	0:ac21159e27f4	1177	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
darran	0:ac21159e27f4	1178	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
darran	0:ac21159e27f4	1179	}
darran	0:ac21159e27f4	1180	#if TCP_QUEUE_OOSEQ
darran	0:ac21159e27f4	1181	/* Received in-sequence data, adjust ooseq data if:
darran	0:ac21159e27f4	1182	- FIN has been received or
darran	0:ac21159e27f4	1183	- inseq overlaps with ooseq */
darran	0:ac21159e27f4	1184	if (pcb->ooseq != NULL) {
darran	0:ac21159e27f4	1185	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	1186	LWIP_DEBUGF(TCP_INPUT_DEBUG,
darran	0:ac21159e27f4	1187	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
darran	0:ac21159e27f4	1188	/* Received in-order FIN means anything that was received
darran	0:ac21159e27f4	1189	* out of order must now have been received in-order, so
darran	0:ac21159e27f4	1190	* bin the ooseq queue */
darran	0:ac21159e27f4	1191	while (pcb->ooseq != NULL) {
darran	0:ac21159e27f4	1192	struct tcp_seg *old_ooseq = pcb->ooseq;
darran	0:ac21159e27f4	1193	pcb->ooseq = pcb->ooseq->next;
darran	0:ac21159e27f4	1194	tcp_seg_free(old_ooseq);
darran	0:ac21159e27f4	1195	}
darran	0:ac21159e27f4	1196	}
darran	0:ac21159e27f4	1197	else {
darran	0:ac21159e27f4	1198	next = pcb->ooseq;
darran	0:ac21159e27f4	1199	/* Remove all segments on ooseq that are covered by inseg already.
darran	0:ac21159e27f4	1200	* FIN is copied from ooseq to inseg if present. */
darran	0:ac21159e27f4	1201	while (next &&
darran	0:ac21159e27f4	1202	TCP_SEQ_GEQ(seqno + tcplen,
darran	0:ac21159e27f4	1203	next->tcphdr->seqno + next->len)) {
darran	0:ac21159e27f4	1204	/* inseg cannot have FIN here (already processed above) */
darran	0:ac21159e27f4	1205	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
darran	0:ac21159e27f4	1206	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
darran	0:ac21159e27f4	1207	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
darran	0:ac21159e27f4	1208	tcplen = TCP_TCPLEN(&inseg);
darran	0:ac21159e27f4	1209	}
darran	0:ac21159e27f4	1210	prev = next;
darran	0:ac21159e27f4	1211	next = next->next;
darran	0:ac21159e27f4	1212	tcp_seg_free(prev);
darran	0:ac21159e27f4	1213	}
darran	0:ac21159e27f4	1214	/* Now trim right side of inseg if it overlaps with the first
darran	0:ac21159e27f4	1215	* segment on ooseq */
darran	0:ac21159e27f4	1216	if (next &&
darran	0:ac21159e27f4	1217	TCP_SEQ_GT(seqno + tcplen,
darran	0:ac21159e27f4	1218	next->tcphdr->seqno)) {
darran	0:ac21159e27f4	1219	/* inseg cannot have FIN here (already processed above) */
darran	0:ac21159e27f4	1220	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
darran	0:ac21159e27f4	1221	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
darran	0:ac21159e27f4	1222	inseg.len -= 1;
darran	0:ac21159e27f4	1223	}
darran	0:ac21159e27f4	1224	pbuf_realloc(inseg.p, inseg.len);
darran	0:ac21159e27f4	1225	tcplen = TCP_TCPLEN(&inseg);
darran	0:ac21159e27f4	1226	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
darran	0:ac21159e27f4	1227	(seqno + tcplen) == next->tcphdr->seqno);
darran	0:ac21159e27f4	1228	}
darran	0:ac21159e27f4	1229	pcb->ooseq = next;
darran	0:ac21159e27f4	1230	}
darran	0:ac21159e27f4	1231	}
darran	0:ac21159e27f4	1232	#endif /* TCP_QUEUE_OOSEQ */
darran	0:ac21159e27f4	1233
darran	0:ac21159e27f4	1234	pcb->rcv_nxt = seqno + tcplen;
darran	0:ac21159e27f4	1235
darran	0:ac21159e27f4	1236	/* Update the receiver's (our) window. */
darran	0:ac21159e27f4	1237	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
darran	0:ac21159e27f4	1238	pcb->rcv_wnd -= tcplen;
darran	0:ac21159e27f4	1239
darran	0:ac21159e27f4	1240	tcp_update_rcv_ann_wnd(pcb);
darran	0:ac21159e27f4	1241
darran	0:ac21159e27f4	1242	/* If there is data in the segment, we make preparations to
darran	0:ac21159e27f4	1243	pass this up to the application. The ->recv_data variable
darran	0:ac21159e27f4	1244	is used for holding the pbuf that goes to the
darran	0:ac21159e27f4	1245	application. The code for reassembling out-of-sequence data
darran	0:ac21159e27f4	1246	chains its data on this pbuf as well.
darran	0:ac21159e27f4	1247
darran	0:ac21159e27f4	1248	If the segment was a FIN, we set the TF_GOT_FIN flag that will
darran	0:ac21159e27f4	1249	be used to indicate to the application that the remote side has
darran	0:ac21159e27f4	1250	closed its end of the connection. */
darran	0:ac21159e27f4	1251	if (inseg.p->tot_len > 0) {
darran	0:ac21159e27f4	1252	recv_data = inseg.p;
darran	0:ac21159e27f4	1253	/* Since this pbuf now is the responsibility of the
darran	0:ac21159e27f4	1254	application, we delete our reference to it so that we won't
darran	0:ac21159e27f4	1255	(mistakingly) deallocate it. */
darran	0:ac21159e27f4	1256	inseg.p = NULL;
darran	0:ac21159e27f4	1257	}
darran	0:ac21159e27f4	1258	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	1259	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
darran	0:ac21159e27f4	1260	recv_flags \|= TF_GOT_FIN;
darran	0:ac21159e27f4	1261	}
darran	0:ac21159e27f4	1262
darran	0:ac21159e27f4	1263	#if TCP_QUEUE_OOSEQ
darran	0:ac21159e27f4	1264	/* We now check if we have segments on the ->ooseq queue that
darran	0:ac21159e27f4	1265	are now in sequence. */
darran	0:ac21159e27f4	1266	while (pcb->ooseq != NULL &&
darran	0:ac21159e27f4	1267	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
darran	0:ac21159e27f4	1268
darran	0:ac21159e27f4	1269	cseg = pcb->ooseq;
darran	0:ac21159e27f4	1270	seqno = pcb->ooseq->tcphdr->seqno;
darran	0:ac21159e27f4	1271
darran	0:ac21159e27f4	1272	pcb->rcv_nxt += TCP_TCPLEN(cseg);
darran	0:ac21159e27f4	1273	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
darran	0:ac21159e27f4	1274	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
darran	0:ac21159e27f4	1275	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
darran	0:ac21159e27f4	1276
darran	0:ac21159e27f4	1277	tcp_update_rcv_ann_wnd(pcb);
darran	0:ac21159e27f4	1278
darran	0:ac21159e27f4	1279	if (cseg->p->tot_len > 0) {
darran	0:ac21159e27f4	1280	/* Chain this pbuf onto the pbuf that we will pass to
darran	0:ac21159e27f4	1281	the application. */
darran	0:ac21159e27f4	1282	if (recv_data) {
darran	0:ac21159e27f4	1283	pbuf_cat(recv_data, cseg->p);
darran	0:ac21159e27f4	1284	} else {
darran	0:ac21159e27f4	1285	recv_data = cseg->p;
darran	0:ac21159e27f4	1286	}
darran	0:ac21159e27f4	1287	cseg->p = NULL;
darran	0:ac21159e27f4	1288	}
darran	0:ac21159e27f4	1289	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	1290	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
darran	0:ac21159e27f4	1291	recv_flags \|= TF_GOT_FIN;
darran	0:ac21159e27f4	1292	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
darran	0:ac21159e27f4	1293	pcb->state = CLOSE_WAIT;
darran	0:ac21159e27f4	1294	}
darran	0:ac21159e27f4	1295	}
darran	0:ac21159e27f4	1296
darran	0:ac21159e27f4	1297	pcb->ooseq = cseg->next;
darran	0:ac21159e27f4	1298	tcp_seg_free(cseg);
darran	0:ac21159e27f4	1299	}
darran	0:ac21159e27f4	1300	#endif /* TCP_QUEUE_OOSEQ */
darran	0:ac21159e27f4	1301
darran	0:ac21159e27f4	1302
darran	0:ac21159e27f4	1303	/* Acknowledge the segment(s). */
darran	0:ac21159e27f4	1304	tcp_ack(pcb);
darran	0:ac21159e27f4	1305
darran	0:ac21159e27f4	1306	} else {
darran	0:ac21159e27f4	1307	/* We get here if the incoming segment is out-of-sequence. */
darran	0:ac21159e27f4	1308	tcp_send_empty_ack(pcb);
darran	0:ac21159e27f4	1309	#if TCP_QUEUE_OOSEQ
darran	0:ac21159e27f4	1310	/* We queue the segment on the ->ooseq queue. */
darran	0:ac21159e27f4	1311	if (pcb->ooseq == NULL) {
darran	0:ac21159e27f4	1312	pcb->ooseq = tcp_seg_copy(&inseg);
darran	0:ac21159e27f4	1313	} else {
darran	0:ac21159e27f4	1314	/* If the queue is not empty, we walk through the queue and
darran	0:ac21159e27f4	1315	try to find a place where the sequence number of the
darran	0:ac21159e27f4	1316	incoming segment is between the sequence numbers of the
darran	0:ac21159e27f4	1317	previous and the next segment on the ->ooseq queue. That is
darran	0:ac21159e27f4	1318	the place where we put the incoming segment. If needed, we
darran	0:ac21159e27f4	1319	trim the second edges of the previous and the incoming
darran	0:ac21159e27f4	1320	segment so that it will fit into the sequence.
darran	0:ac21159e27f4	1321
darran	0:ac21159e27f4	1322	If the incoming segment has the same sequence number as a
darran	0:ac21159e27f4	1323	segment on the ->ooseq queue, we discard the segment that
darran	0:ac21159e27f4	1324	contains less data. */
darran	0:ac21159e27f4	1325
darran	0:ac21159e27f4	1326	prev = NULL;
darran	0:ac21159e27f4	1327	for(next = pcb->ooseq; next != NULL; next = next->next) {
darran	0:ac21159e27f4	1328	if (seqno == next->tcphdr->seqno) {
darran	0:ac21159e27f4	1329	/* The sequence number of the incoming segment is the
darran	0:ac21159e27f4	1330	same as the sequence number of the segment on
darran	0:ac21159e27f4	1331	->ooseq. We check the lengths to see which one to
darran	0:ac21159e27f4	1332	discard. */
darran	0:ac21159e27f4	1333	if (inseg.len > next->len) {
darran	0:ac21159e27f4	1334	/* The incoming segment is larger than the old
darran	0:ac21159e27f4	1335	segment. We replace some segments with the new
darran	0:ac21159e27f4	1336	one. */
darran	0:ac21159e27f4	1337	cseg = tcp_seg_copy(&inseg);
darran	0:ac21159e27f4	1338	if (cseg != NULL) {
darran	0:ac21159e27f4	1339	if (prev != NULL) {
darran	0:ac21159e27f4	1340	prev->next = cseg;
darran	0:ac21159e27f4	1341	} else {
darran	0:ac21159e27f4	1342	pcb->ooseq = cseg;
darran	0:ac21159e27f4	1343	}
darran	0:ac21159e27f4	1344	tcp_oos_insert_segment(cseg, next);
darran	0:ac21159e27f4	1345	}
darran	0:ac21159e27f4	1346	break;
darran	0:ac21159e27f4	1347	} else {
darran	0:ac21159e27f4	1348	/* Either the lenghts are the same or the incoming
darran	0:ac21159e27f4	1349	segment was smaller than the old one; in either
darran	0:ac21159e27f4	1350	case, we ditch the incoming segment. */
darran	0:ac21159e27f4	1351	break;
darran	0:ac21159e27f4	1352	}
darran	0:ac21159e27f4	1353	} else {
darran	0:ac21159e27f4	1354	if (prev == NULL) {
darran	0:ac21159e27f4	1355	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
darran	0:ac21159e27f4	1356	/* The sequence number of the incoming segment is lower
darran	0:ac21159e27f4	1357	than the sequence number of the first segment on the
darran	0:ac21159e27f4	1358	queue. We put the incoming segment first on the
darran	0:ac21159e27f4	1359	queue. */
darran	0:ac21159e27f4	1360	cseg = tcp_seg_copy(&inseg);
darran	0:ac21159e27f4	1361	if (cseg != NULL) {
darran	0:ac21159e27f4	1362	pcb->ooseq = cseg;
darran	0:ac21159e27f4	1363	tcp_oos_insert_segment(cseg, next);
darran	0:ac21159e27f4	1364	}
darran	0:ac21159e27f4	1365	break;
darran	0:ac21159e27f4	1366	}
darran	0:ac21159e27f4	1367	} else {
darran	0:ac21159e27f4	1368	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
darran	0:ac21159e27f4	1369	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
darran	0:ac21159e27f4	1370	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
darran	0:ac21159e27f4	1371	/* The sequence number of the incoming segment is in
darran	0:ac21159e27f4	1372	between the sequence numbers of the previous and
darran	0:ac21159e27f4	1373	the next segment on ->ooseq. We trim trim the previous
darran	0:ac21159e27f4	1374	segment, delete next segments that included in received segment
darran	0:ac21159e27f4	1375	and trim received, if needed. */
darran	0:ac21159e27f4	1376	cseg = tcp_seg_copy(&inseg);
darran	0:ac21159e27f4	1377	if (cseg != NULL) {
darran	0:ac21159e27f4	1378	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
darran	0:ac21159e27f4	1379	/* We need to trim the prev segment. */
darran	0:ac21159e27f4	1380	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
darran	0:ac21159e27f4	1381	pbuf_realloc(prev->p, prev->len);
darran	0:ac21159e27f4	1382	}
darran	0:ac21159e27f4	1383	prev->next = cseg;
darran	0:ac21159e27f4	1384	tcp_oos_insert_segment(cseg, next);
darran	0:ac21159e27f4	1385	}
darran	0:ac21159e27f4	1386	break;
darran	0:ac21159e27f4	1387	}
darran	0:ac21159e27f4	1388	}
darran	0:ac21159e27f4	1389	/* If the "next" segment is the last segment on the
darran	0:ac21159e27f4	1390	ooseq queue, we add the incoming segment to the end
darran	0:ac21159e27f4	1391	of the list. */
darran	0:ac21159e27f4	1392	if (next->next == NULL &&
darran	0:ac21159e27f4	1393	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
darran	0:ac21159e27f4	1394	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
darran	0:ac21159e27f4	1395	/* segment "next" already contains all data */
darran	0:ac21159e27f4	1396	break;
darran	0:ac21159e27f4	1397	}
darran	0:ac21159e27f4	1398	next->next = tcp_seg_copy(&inseg);
darran	0:ac21159e27f4	1399	if (next->next != NULL) {
darran	0:ac21159e27f4	1400	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
darran	0:ac21159e27f4	1401	/* We need to trim the last segment. */
darran	0:ac21159e27f4	1402	next->len = (u16_t)(seqno - next->tcphdr->seqno);
darran	0:ac21159e27f4	1403	pbuf_realloc(next->p, next->len);
darran	0:ac21159e27f4	1404	}
darran	0:ac21159e27f4	1405	}
darran	0:ac21159e27f4	1406	break;
darran	0:ac21159e27f4	1407	}
darran	0:ac21159e27f4	1408	}
darran	0:ac21159e27f4	1409	prev = next;
darran	0:ac21159e27f4	1410	}
darran	0:ac21159e27f4	1411	}
darran	0:ac21159e27f4	1412	#endif /* TCP_QUEUE_OOSEQ */
darran	0:ac21159e27f4	1413
darran	0:ac21159e27f4	1414	}
darran	0:ac21159e27f4	1415	} else {
darran	0:ac21159e27f4	1416	/* The incoming segment is not withing the window. */
darran	0:ac21159e27f4	1417	tcp_send_empty_ack(pcb);
darran	0:ac21159e27f4	1418	}
darran	0:ac21159e27f4	1419	} else {
darran	0:ac21159e27f4	1420	/* Segments with length 0 is taken care of here. Segments that
darran	0:ac21159e27f4	1421	fall out of the window are ACKed. */
darran	0:ac21159e27f4	1422	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
darran	0:ac21159e27f4	1423	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
darran	0:ac21159e27f4	1424	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
darran	0:ac21159e27f4	1425	tcp_ack_now(pcb);
darran	0:ac21159e27f4	1426	}
darran	0:ac21159e27f4	1427	}
darran	0:ac21159e27f4	1428	}
darran	0:ac21159e27f4	1429
darran	0:ac21159e27f4	1430	/**
darran	0:ac21159e27f4	1431	* Parses the options contained in the incoming segment.
darran	0:ac21159e27f4	1432	*
darran	0:ac21159e27f4	1433	* Called from tcp_listen_input() and tcp_process().
darran	0:ac21159e27f4	1434	* Currently, only the MSS option is supported!
darran	0:ac21159e27f4	1435	*
darran	0:ac21159e27f4	1436	* @param pcb the tcp_pcb for which a segment arrived
darran	0:ac21159e27f4	1437	*/
darran	0:ac21159e27f4	1438	static void
darran	0:ac21159e27f4	1439	tcp_parseopt(struct tcp_pcb *pcb)
darran	0:ac21159e27f4	1440	{
darran	0:ac21159e27f4	1441	u16_t c, max_c;
darran	0:ac21159e27f4	1442	u16_t mss;
darran	0:ac21159e27f4	1443	u8_t *opts, opt;
darran	0:ac21159e27f4	1444	#if LWIP_TCP_TIMESTAMPS
darran	0:ac21159e27f4	1445	u32_t tsval;
darran	0:ac21159e27f4	1446	#endif
darran	0:ac21159e27f4	1447
darran	0:ac21159e27f4	1448	opts = (u8_t *)tcphdr + TCP_HLEN;
darran	0:ac21159e27f4	1449
darran	0:ac21159e27f4	1450	/* Parse the TCP MSS option, if present. */
darran	0:ac21159e27f4	1451	if(TCPH_HDRLEN(tcphdr) > 0x5) {
darran	0:ac21159e27f4	1452	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
darran	0:ac21159e27f4	1453	for (c = 0; c < max_c; ) {
darran	0:ac21159e27f4	1454	opt = opts[c];
darran	0:ac21159e27f4	1455	switch (opt) {
darran	0:ac21159e27f4	1456	case 0x00:
darran	0:ac21159e27f4	1457	/* End of options. */
darran	0:ac21159e27f4	1458	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
darran	0:ac21159e27f4	1459	return;
darran	0:ac21159e27f4	1460	case 0x01:
darran	0:ac21159e27f4	1461	/* NOP option. */
darran	0:ac21159e27f4	1462	++c;
darran	0:ac21159e27f4	1463	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
darran	0:ac21159e27f4	1464	break;
darran	0:ac21159e27f4	1465	case 0x02:
darran	0:ac21159e27f4	1466	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
darran	0:ac21159e27f4	1467	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
darran	0:ac21159e27f4	1468	/* Bad length */
darran	0:ac21159e27f4	1469	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
darran	0:ac21159e27f4	1470	return;
darran	0:ac21159e27f4	1471	}
darran	0:ac21159e27f4	1472	/* An MSS option with the right option length. */
darran	0:ac21159e27f4	1473	mss = (opts[c + 2] << 8) \| opts[c + 3];
darran	0:ac21159e27f4	1474	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
darran	0:ac21159e27f4	1475	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
darran	0:ac21159e27f4	1476	/* Advance to next option */
darran	0:ac21159e27f4	1477	c += 0x04;
darran	0:ac21159e27f4	1478	break;
darran	0:ac21159e27f4	1479	#if LWIP_TCP_TIMESTAMPS
darran	0:ac21159e27f4	1480	case 0x08:
darran	0:ac21159e27f4	1481	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
darran	0:ac21159e27f4	1482	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
darran	0:ac21159e27f4	1483	/* Bad length */
darran	0:ac21159e27f4	1484	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
darran	0:ac21159e27f4	1485	return;
darran	0:ac21159e27f4	1486	}
darran	0:ac21159e27f4	1487	/* TCP timestamp option with valid length */
darran	0:ac21159e27f4	1488	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
darran	0:ac21159e27f4	1489	(opts[c+4] << 16) \| (opts[c+5] << 24);
darran	0:ac21159e27f4	1490	if (flags & TCP_SYN) {
darran	0:ac21159e27f4	1491	pcb->ts_recent = ntohl(tsval);
darran	0:ac21159e27f4	1492	pcb->flags \|= TF_TIMESTAMP;
darran	0:ac21159e27f4	1493	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
darran	0:ac21159e27f4	1494	pcb->ts_recent = ntohl(tsval);
darran	0:ac21159e27f4	1495	}
darran	0:ac21159e27f4	1496	/* Advance to next option */
darran	0:ac21159e27f4	1497	c += 0x0A;
darran	0:ac21159e27f4	1498	break;
darran	0:ac21159e27f4	1499	#endif
darran	0:ac21159e27f4	1500	default:
darran	0:ac21159e27f4	1501	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
darran	0:ac21159e27f4	1502	if (opts[c + 1] == 0) {
darran	0:ac21159e27f4	1503	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
darran	0:ac21159e27f4	1504	/* If the length field is zero, the options are malformed
darran	0:ac21159e27f4	1505	and we don't process them further. */
darran	0:ac21159e27f4	1506	return;
darran	0:ac21159e27f4	1507	}
darran	0:ac21159e27f4	1508	/* All other options have a length field, so that we easily
darran	0:ac21159e27f4	1509	can skip past them. */
darran	0:ac21159e27f4	1510	c += opts[c + 1];
darran	0:ac21159e27f4	1511	}
darran	0:ac21159e27f4	1512	}
darran	0:ac21159e27f4	1513	}
darran	0:ac21159e27f4	1514	}
darran	0:ac21159e27f4	1515
darran	0:ac21159e27f4	1516	#endif /* LWIP_TCP */

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	02 Jul 2010
Imports:	2
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	1

lwip/core/tcp_in.c@0:ac21159e27f4, 2010-07-02 (annotated)

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