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lwip/core/tcp_in.c@0:632c9925f013, 2010-06-11 (annotated)

Committer:: donatien
Date:: Fri Jun 11 16:05:15 2010 +0000
Revision:: 0:632c9925f013
Child:: 5:dd63a1e02b1b

Who changed what in which revision?

User	Revision	Line number	New contents of line
donatien	0:632c9925f013	1	/**
donatien	0:632c9925f013	2	* @file
donatien	0:632c9925f013	3	* Transmission Control Protocol, incoming traffic
donatien	0:632c9925f013	4	*
donatien	0:632c9925f013	5	* The input processing functions of the TCP layer.
donatien	0:632c9925f013	6	*
donatien	0:632c9925f013	7	* These functions are generally called in the order (ip_input() ->)
donatien	0:632c9925f013	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
donatien	0:632c9925f013	9	*
donatien	0:632c9925f013	10	*/
donatien	0:632c9925f013	11
donatien	0:632c9925f013	12	/*
donatien	0:632c9925f013	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
donatien	0:632c9925f013	14	* All rights reserved.
donatien	0:632c9925f013	15	*
donatien	0:632c9925f013	16	* Redistribution and use in source and binary forms, with or without modification,
donatien	0:632c9925f013	17	* are permitted provided that the following conditions are met:
donatien	0:632c9925f013	18	*
donatien	0:632c9925f013	19	* 1. Redistributions of source code must retain the above copyright notice,
donatien	0:632c9925f013	20	* this list of conditions and the following disclaimer.
donatien	0:632c9925f013	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
donatien	0:632c9925f013	22	* this list of conditions and the following disclaimer in the documentation
donatien	0:632c9925f013	23	* and/or other materials provided with the distribution.
donatien	0:632c9925f013	24	* 3. The name of the author may not be used to endorse or promote products
donatien	0:632c9925f013	25	* derived from this software without specific prior written permission.
donatien	0:632c9925f013	26	*
donatien	0:632c9925f013	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
donatien	0:632c9925f013	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
donatien	0:632c9925f013	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
donatien	0:632c9925f013	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
donatien	0:632c9925f013	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
donatien	0:632c9925f013	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
donatien	0:632c9925f013	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
donatien	0:632c9925f013	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
donatien	0:632c9925f013	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
donatien	0:632c9925f013	36	* OF SUCH DAMAGE.
donatien	0:632c9925f013	37	*
donatien	0:632c9925f013	38	* This file is part of the lwIP TCP/IP stack.
donatien	0:632c9925f013	39	*
donatien	0:632c9925f013	40	* Author: Adam Dunkels <adam@sics.se>
donatien	0:632c9925f013	41	*
donatien	0:632c9925f013	42	*/
donatien	0:632c9925f013	43
donatien	0:632c9925f013	44	#include "lwip/opt.h"
donatien	0:632c9925f013	45
donatien	0:632c9925f013	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
donatien	0:632c9925f013	47
donatien	0:632c9925f013	48	#include "lwip/tcp_impl.h"
donatien	0:632c9925f013	49	#include "lwip/def.h"
donatien	0:632c9925f013	50	#include "lwip/ip_addr.h"
donatien	0:632c9925f013	51	#include "lwip/netif.h"
donatien	0:632c9925f013	52	#include "lwip/mem.h"
donatien	0:632c9925f013	53	#include "lwip/memp.h"
donatien	0:632c9925f013	54	#include "lwip/inet_chksum.h"
donatien	0:632c9925f013	55	#include "lwip/stats.h"
donatien	0:632c9925f013	56	#include "lwip/snmp.h"
donatien	0:632c9925f013	57	#include "arch/perf.h"
donatien	0:632c9925f013	58
donatien	0:632c9925f013	59	/* These variables are global to all functions involved in the input
donatien	0:632c9925f013	60	processing of TCP segments. They are set by the tcp_input()
donatien	0:632c9925f013	61	function. */
donatien	0:632c9925f013	62	static struct tcp_seg inseg;
donatien	0:632c9925f013	63	static struct tcp_hdr *tcphdr;
donatien	0:632c9925f013	64	static struct ip_hdr *iphdr;
donatien	0:632c9925f013	65	static u32_t seqno, ackno;
donatien	0:632c9925f013	66	static u8_t flags;
donatien	0:632c9925f013	67	static u16_t tcplen;
donatien	0:632c9925f013	68
donatien	0:632c9925f013	69	static u8_t recv_flags;
donatien	0:632c9925f013	70	static struct pbuf *recv_data;
donatien	0:632c9925f013	71
donatien	0:632c9925f013	72	struct tcp_pcb *tcp_input_pcb;
donatien	0:632c9925f013	73
donatien	0:632c9925f013	74	/* Forward declarations. */
donatien	0:632c9925f013	75	static err_t tcp_process(struct tcp_pcb *pcb);
donatien	0:632c9925f013	76	static void tcp_receive(struct tcp_pcb *pcb);
donatien	0:632c9925f013	77	static void tcp_parseopt(struct tcp_pcb *pcb);
donatien	0:632c9925f013	78
donatien	0:632c9925f013	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
donatien	0:632c9925f013	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
donatien	0:632c9925f013	81
donatien	0:632c9925f013	82	/**
donatien	0:632c9925f013	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
donatien	0:632c9925f013	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
donatien	0:632c9925f013	85	* the TCP finite state machine. This function is called by the IP layer (in
donatien	0:632c9925f013	86	* ip_input()).
donatien	0:632c9925f013	87	*
donatien	0:632c9925f013	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
donatien	0:632c9925f013	89	* @param inp network interface on which this segment was received
donatien	0:632c9925f013	90	*/
donatien	0:632c9925f013	91	void
donatien	0:632c9925f013	92	tcp_input(struct pbuf p, struct netif inp)
donatien	0:632c9925f013	93	{
donatien	0:632c9925f013	94	struct tcp_pcb pcb, prev;
donatien	0:632c9925f013	95	struct tcp_pcb_listen *lpcb;
donatien	0:632c9925f013	96	u8_t hdrlen;
donatien	0:632c9925f013	97	err_t err;
donatien	0:632c9925f013	98
donatien	0:632c9925f013	99	PERF_START;
donatien	0:632c9925f013	100
donatien	0:632c9925f013	101	TCP_STATS_INC(tcp.recv);
donatien	0:632c9925f013	102	snmp_inc_tcpinsegs();
donatien	0:632c9925f013	103
donatien	0:632c9925f013	104	iphdr = (struct ip_hdr *)p->payload;
donatien	0:632c9925f013	105	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
donatien	0:632c9925f013	106
donatien	0:632c9925f013	107	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	108	tcp_debug_print(tcphdr);
donatien	0:632c9925f013	109	#endif
donatien	0:632c9925f013	110
donatien	0:632c9925f013	111	/* remove header from payload */
donatien	0:632c9925f013	112	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
donatien	0:632c9925f013	113	/* drop short packets */
donatien	0:632c9925f013	114	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
donatien	0:632c9925f013	115	TCP_STATS_INC(tcp.lenerr);
donatien	0:632c9925f013	116	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	117	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	118	pbuf_free(p);
donatien	0:632c9925f013	119	return;
donatien	0:632c9925f013	120	}
donatien	0:632c9925f013	121
donatien	0:632c9925f013	122	/* Don't even process incoming broadcasts/multicasts. */
donatien	0:632c9925f013	123	if (ip_addr_isbroadcast(&(iphdr->dest), inp) \|\|
donatien	0:632c9925f013	124	ip_addr_ismulticast(&(iphdr->dest))) {
donatien	0:632c9925f013	125	TCP_STATS_INC(tcp.proterr);
donatien	0:632c9925f013	126	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	127	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	128	pbuf_free(p);
donatien	0:632c9925f013	129	return;
donatien	0:632c9925f013	130	}
donatien	0:632c9925f013	131
donatien	0:632c9925f013	132	#if CHECKSUM_CHECK_TCP
donatien	0:632c9925f013	133	/* Verify TCP checksum. */
donatien	0:632c9925f013	134	if (inet_chksum_pseudo(p, &iphdr->src, &iphdr->dest,
donatien	0:632c9925f013	135	IP_PROTO_TCP, p->tot_len) != 0) {
donatien	0:632c9925f013	136	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
donatien	0:632c9925f013	137	inet_chksum_pseudo(p, &iphdr->src, &iphdr->dest,
donatien	0:632c9925f013	138	IP_PROTO_TCP, p->tot_len)));
donatien	0:632c9925f013	139	#if TCP_DEBUG
donatien	0:632c9925f013	140	tcp_debug_print(tcphdr);
donatien	0:632c9925f013	141	#endif /* TCP_DEBUG */
donatien	0:632c9925f013	142	TCP_STATS_INC(tcp.chkerr);
donatien	0:632c9925f013	143	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	144	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	145	pbuf_free(p);
donatien	0:632c9925f013	146	return;
donatien	0:632c9925f013	147	}
donatien	0:632c9925f013	148	#endif
donatien	0:632c9925f013	149
donatien	0:632c9925f013	150	/* Move the payload pointer in the pbuf so that it points to the
donatien	0:632c9925f013	151	TCP data instead of the TCP header. */
donatien	0:632c9925f013	152	hdrlen = TCPH_HDRLEN(tcphdr);
donatien	0:632c9925f013	153	if(pbuf_header(p, -(hdrlen * 4))){
donatien	0:632c9925f013	154	/* drop short packets */
donatien	0:632c9925f013	155	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
donatien	0:632c9925f013	156	TCP_STATS_INC(tcp.lenerr);
donatien	0:632c9925f013	157	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	158	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	159	pbuf_free(p);
donatien	0:632c9925f013	160	return;
donatien	0:632c9925f013	161	}
donatien	0:632c9925f013	162
donatien	0:632c9925f013	163	/* Convert fields in TCP header to host byte order. */
donatien	0:632c9925f013	164	tcphdr->src = ntohs(tcphdr->src);
donatien	0:632c9925f013	165	tcphdr->dest = ntohs(tcphdr->dest);
donatien	0:632c9925f013	166	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
donatien	0:632c9925f013	167	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
donatien	0:632c9925f013	168	tcphdr->wnd = ntohs(tcphdr->wnd);
donatien	0:632c9925f013	169
donatien	0:632c9925f013	170	flags = TCPH_FLAGS(tcphdr);
donatien	0:632c9925f013	171	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
donatien	0:632c9925f013	172
donatien	0:632c9925f013	173	/* Demultiplex an incoming segment. First, we check if it is destined
donatien	0:632c9925f013	174	for an active connection. */
donatien	0:632c9925f013	175	prev = NULL;
donatien	0:632c9925f013	176
donatien	0:632c9925f013	177
donatien	0:632c9925f013	178	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
donatien	0:632c9925f013	179	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
donatien	0:632c9925f013	180	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
donatien	0:632c9925f013	181	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
donatien	0:632c9925f013	182	if (pcb->remote_port == tcphdr->src &&
donatien	0:632c9925f013	183	pcb->local_port == tcphdr->dest &&
donatien	0:632c9925f013	184	ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
donatien	0:632c9925f013	185	ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
donatien	0:632c9925f013	186
donatien	0:632c9925f013	187	/* Move this PCB to the front of the list so that subsequent
donatien	0:632c9925f013	188	lookups will be faster (we exploit locality in TCP segment
donatien	0:632c9925f013	189	arrivals). */
donatien	0:632c9925f013	190	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
donatien	0:632c9925f013	191	if (prev != NULL) {
donatien	0:632c9925f013	192	prev->next = pcb->next;
donatien	0:632c9925f013	193	pcb->next = tcp_active_pcbs;
donatien	0:632c9925f013	194	tcp_active_pcbs = pcb;
donatien	0:632c9925f013	195	}
donatien	0:632c9925f013	196	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
donatien	0:632c9925f013	197	break;
donatien	0:632c9925f013	198	}
donatien	0:632c9925f013	199	prev = pcb;
donatien	0:632c9925f013	200	}
donatien	0:632c9925f013	201
donatien	0:632c9925f013	202	if (pcb == NULL) {
donatien	0:632c9925f013	203	/* If it did not go to an active connection, we check the connections
donatien	0:632c9925f013	204	in the TIME-WAIT state. */
donatien	0:632c9925f013	205	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
donatien	0:632c9925f013	206	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
donatien	0:632c9925f013	207	if (pcb->remote_port == tcphdr->src &&
donatien	0:632c9925f013	208	pcb->local_port == tcphdr->dest &&
donatien	0:632c9925f013	209	ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
donatien	0:632c9925f013	210	ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
donatien	0:632c9925f013	211	/* We don't really care enough to move this PCB to the front
donatien	0:632c9925f013	212	of the list since we are not very likely to receive that
donatien	0:632c9925f013	213	many segments for connections in TIME-WAIT. */
donatien	0:632c9925f013	214	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
donatien	0:632c9925f013	215	tcp_timewait_input(pcb);
donatien	0:632c9925f013	216	pbuf_free(p);
donatien	0:632c9925f013	217	return;
donatien	0:632c9925f013	218	}
donatien	0:632c9925f013	219	}
donatien	0:632c9925f013	220
donatien	0:632c9925f013	221	/* Finally, if we still did not get a match, we check all PCBs that
donatien	0:632c9925f013	222	are LISTENing for incoming connections. */
donatien	0:632c9925f013	223	prev = NULL;
donatien	0:632c9925f013	224	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
donatien	0:632c9925f013	225	if ((ip_addr_isany(&(lpcb->local_ip)) \|\|
donatien	0:632c9925f013	226	ip_addr_cmp(&(lpcb->local_ip), &(iphdr->dest))) &&
donatien	0:632c9925f013	227	lpcb->local_port == tcphdr->dest) {
donatien	0:632c9925f013	228	/* Move this PCB to the front of the list so that subsequent
donatien	0:632c9925f013	229	lookups will be faster (we exploit locality in TCP segment
donatien	0:632c9925f013	230	arrivals). */
donatien	0:632c9925f013	231	if (prev != NULL) {
donatien	0:632c9925f013	232	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
donatien	0:632c9925f013	233	/* our successor is the remainder of the listening list */
donatien	0:632c9925f013	234	lpcb->next = tcp_listen_pcbs.listen_pcbs;
donatien	0:632c9925f013	235	/* put this listening pcb at the head of the listening list */
donatien	0:632c9925f013	236	tcp_listen_pcbs.listen_pcbs = lpcb;
donatien	0:632c9925f013	237	}
donatien	0:632c9925f013	238
donatien	0:632c9925f013	239	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
donatien	0:632c9925f013	240	tcp_listen_input(lpcb);
donatien	0:632c9925f013	241	pbuf_free(p);
donatien	0:632c9925f013	242	return;
donatien	0:632c9925f013	243	}
donatien	0:632c9925f013	244	prev = (struct tcp_pcb *)lpcb;
donatien	0:632c9925f013	245	}
donatien	0:632c9925f013	246	}
donatien	0:632c9925f013	247
donatien	0:632c9925f013	248	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	249	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
donatien	0:632c9925f013	250	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
donatien	0:632c9925f013	251	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
donatien	0:632c9925f013	252	#endif /* TCP_INPUT_DEBUG */
donatien	0:632c9925f013	253
donatien	0:632c9925f013	254
donatien	0:632c9925f013	255	if (pcb != NULL) {
donatien	0:632c9925f013	256	/* The incoming segment belongs to a connection. */
donatien	0:632c9925f013	257	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	258	#if TCP_DEBUG
donatien	0:632c9925f013	259	tcp_debug_print_state(pcb->state);
donatien	0:632c9925f013	260	#endif /* TCP_DEBUG */
donatien	0:632c9925f013	261	#endif /* TCP_INPUT_DEBUG */
donatien	0:632c9925f013	262
donatien	0:632c9925f013	263	/* Set up a tcp_seg structure. */
donatien	0:632c9925f013	264	inseg.next = NULL;
donatien	0:632c9925f013	265	inseg.len = p->tot_len;
donatien	0:632c9925f013	266	inseg.dataptr = p->payload;
donatien	0:632c9925f013	267	inseg.p = p;
donatien	0:632c9925f013	268	inseg.tcphdr = tcphdr;
donatien	0:632c9925f013	269
donatien	0:632c9925f013	270	recv_data = NULL;
donatien	0:632c9925f013	271	recv_flags = 0;
donatien	0:632c9925f013	272
donatien	0:632c9925f013	273	/* If there is data which was previously "refused" by upper layer */
donatien	0:632c9925f013	274	if (pcb->refused_data != NULL) {
donatien	0:632c9925f013	275	/* Notify again application with data previously received. */
donatien	0:632c9925f013	276	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
donatien	0:632c9925f013	277	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
donatien	0:632c9925f013	278	if (err == ERR_OK) {
donatien	0:632c9925f013	279	pcb->refused_data = NULL;
donatien	0:632c9925f013	280	} else {
donatien	0:632c9925f013	281	/* if err == ERR_ABRT, 'pcb' is already deallocated */
donatien	0:632c9925f013	282	/* drop incoming packets, because pcb is "full" */
donatien	0:632c9925f013	283	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
donatien	0:632c9925f013	284	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	285	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	286	pbuf_free(p);
donatien	0:632c9925f013	287	return;
donatien	0:632c9925f013	288	}
donatien	0:632c9925f013	289	}
donatien	0:632c9925f013	290	tcp_input_pcb = pcb;
donatien	0:632c9925f013	291	err = tcp_process(pcb);
donatien	0:632c9925f013	292	/* A return value of ERR_ABRT means that tcp_abort() was called
donatien	0:632c9925f013	293	and that the pcb has been freed. If so, we don't do anything. */
donatien	0:632c9925f013	294	if (err != ERR_ABRT) {
donatien	0:632c9925f013	295	if (recv_flags & TF_RESET) {
donatien	0:632c9925f013	296	/* TF_RESET means that the connection was reset by the other
donatien	0:632c9925f013	297	end. We then call the error callback to inform the
donatien	0:632c9925f013	298	application that the connection is dead before we
donatien	0:632c9925f013	299	deallocate the PCB. */
donatien	0:632c9925f013	300	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
donatien	0:632c9925f013	301	tcp_pcb_remove(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	302	memp_free(MEMP_TCP_PCB, pcb);
donatien	0:632c9925f013	303	} else if (recv_flags & TF_CLOSED) {
donatien	0:632c9925f013	304	/* The connection has been closed and we will deallocate the
donatien	0:632c9925f013	305	PCB. */
donatien	0:632c9925f013	306	tcp_pcb_remove(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	307	memp_free(MEMP_TCP_PCB, pcb);
donatien	0:632c9925f013	308	} else {
donatien	0:632c9925f013	309	err = ERR_OK;
donatien	0:632c9925f013	310	/* If the application has registered a "sent" function to be
donatien	0:632c9925f013	311	called when new send buffer space is available, we call it
donatien	0:632c9925f013	312	now. */
donatien	0:632c9925f013	313	if (pcb->acked > 0) {
donatien	0:632c9925f013	314	TCP_EVENT_SENT(pcb, pcb->acked, err);
donatien	0:632c9925f013	315	if (err == ERR_ABRT) {
donatien	0:632c9925f013	316	goto aborted;
donatien	0:632c9925f013	317	}
donatien	0:632c9925f013	318	}
donatien	0:632c9925f013	319
donatien	0:632c9925f013	320	if (recv_data != NULL) {
donatien	0:632c9925f013	321	if(flags & TCP_PSH) {
donatien	0:632c9925f013	322	recv_data->flags \|= PBUF_FLAG_PUSH;
donatien	0:632c9925f013	323	}
donatien	0:632c9925f013	324
donatien	0:632c9925f013	325	/* Notify application that data has been received. */
donatien	0:632c9925f013	326	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
donatien	0:632c9925f013	327	if (err == ERR_ABRT) {
donatien	0:632c9925f013	328	goto aborted;
donatien	0:632c9925f013	329	}
donatien	0:632c9925f013	330
donatien	0:632c9925f013	331	/* If the upper layer can't receive this data, store it */
donatien	0:632c9925f013	332	if (err != ERR_OK) {
donatien	0:632c9925f013	333	pcb->refused_data = recv_data;
donatien	0:632c9925f013	334	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
donatien	0:632c9925f013	335	}
donatien	0:632c9925f013	336	}
donatien	0:632c9925f013	337
donatien	0:632c9925f013	338	/* If a FIN segment was received, we call the callback
donatien	0:632c9925f013	339	function with a NULL buffer to indicate EOF. */
donatien	0:632c9925f013	340	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	341	/* correct rcv_wnd as the application won't call tcp_recved()
donatien	0:632c9925f013	342	for the FIN's seqno */
donatien	0:632c9925f013	343	if (pcb->rcv_wnd != TCP_WND) {
donatien	0:632c9925f013	344	pcb->rcv_wnd++;
donatien	0:632c9925f013	345	}
donatien	0:632c9925f013	346	TCP_EVENT_RECV(pcb, NULL, ERR_OK, err);
donatien	0:632c9925f013	347	if (err == ERR_ABRT) {
donatien	0:632c9925f013	348	goto aborted;
donatien	0:632c9925f013	349	}
donatien	0:632c9925f013	350	}
donatien	0:632c9925f013	351
donatien	0:632c9925f013	352	tcp_input_pcb = NULL;
donatien	0:632c9925f013	353	/* Try to send something out. */
donatien	0:632c9925f013	354	tcp_output(pcb);
donatien	0:632c9925f013	355	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	356	#if TCP_DEBUG
donatien	0:632c9925f013	357	tcp_debug_print_state(pcb->state);
donatien	0:632c9925f013	358	#endif /* TCP_DEBUG */
donatien	0:632c9925f013	359	#endif /* TCP_INPUT_DEBUG */
donatien	0:632c9925f013	360	}
donatien	0:632c9925f013	361	}
donatien	0:632c9925f013	362	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
donatien	0:632c9925f013	363	Below this line, 'pcb' may not be dereferenced! */
donatien	0:632c9925f013	364	aborted:
donatien	0:632c9925f013	365	tcp_input_pcb = NULL;
donatien	0:632c9925f013	366
donatien	0:632c9925f013	367
donatien	0:632c9925f013	368	/* give up our reference to inseg.p */
donatien	0:632c9925f013	369	if (inseg.p != NULL)
donatien	0:632c9925f013	370	{
donatien	0:632c9925f013	371	pbuf_free(inseg.p);
donatien	0:632c9925f013	372	inseg.p = NULL;
donatien	0:632c9925f013	373	}
donatien	0:632c9925f013	374	} else {
donatien	0:632c9925f013	375
donatien	0:632c9925f013	376	/* If no matching PCB was found, send a TCP RST (reset) to the
donatien	0:632c9925f013	377	sender. */
donatien	0:632c9925f013	378	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
donatien	0:632c9925f013	379	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
donatien	0:632c9925f013	380	TCP_STATS_INC(tcp.proterr);
donatien	0:632c9925f013	381	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	382	tcp_rst(ackno, seqno + tcplen,
donatien	0:632c9925f013	383	&(iphdr->dest), &(iphdr->src),
donatien	0:632c9925f013	384	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	385	}
donatien	0:632c9925f013	386	pbuf_free(p);
donatien	0:632c9925f013	387	}
donatien	0:632c9925f013	388
donatien	0:632c9925f013	389	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
donatien	0:632c9925f013	390	PERF_STOP("tcp_input");
donatien	0:632c9925f013	391	}
donatien	0:632c9925f013	392
donatien	0:632c9925f013	393	/**
donatien	0:632c9925f013	394	* Called by tcp_input() when a segment arrives for a listening
donatien	0:632c9925f013	395	* connection (from tcp_input()).
donatien	0:632c9925f013	396	*
donatien	0:632c9925f013	397	* @param pcb the tcp_pcb_listen for which a segment arrived
donatien	0:632c9925f013	398	* @return ERR_OK if the segment was processed
donatien	0:632c9925f013	399	* another err_t on error
donatien	0:632c9925f013	400	*
donatien	0:632c9925f013	401	* @note the return value is not (yet?) used in tcp_input()
donatien	0:632c9925f013	402	* @note the segment which arrived is saved in global variables, therefore only the pcb
donatien	0:632c9925f013	403	* involved is passed as a parameter to this function
donatien	0:632c9925f013	404	*/
donatien	0:632c9925f013	405	static err_t
donatien	0:632c9925f013	406	tcp_listen_input(struct tcp_pcb_listen *pcb)
donatien	0:632c9925f013	407	{
donatien	0:632c9925f013	408	struct tcp_pcb *npcb;
donatien	0:632c9925f013	409	err_t rc;
donatien	0:632c9925f013	410
donatien	0:632c9925f013	411	/* In the LISTEN state, we check for incoming SYN segments,
donatien	0:632c9925f013	412	creates a new PCB, and responds with a SYN\|ACK. */
donatien	0:632c9925f013	413	if (flags & TCP_ACK) {
donatien	0:632c9925f013	414	/* For incoming segments with the ACK flag set, respond with a
donatien	0:632c9925f013	415	RST. */
donatien	0:632c9925f013	416	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
donatien	0:632c9925f013	417	tcp_rst(ackno + 1, seqno + tcplen,
donatien	0:632c9925f013	418	&(iphdr->dest), &(iphdr->src),
donatien	0:632c9925f013	419	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	420	} else if (flags & TCP_SYN) {
donatien	0:632c9925f013	421	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
donatien	0:632c9925f013	422	#if TCP_LISTEN_BACKLOG
donatien	0:632c9925f013	423	if (pcb->accepts_pending >= pcb->backlog) {
donatien	0:632c9925f013	424	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
donatien	0:632c9925f013	425	return ERR_ABRT;
donatien	0:632c9925f013	426	}
donatien	0:632c9925f013	427	#endif /* TCP_LISTEN_BACKLOG */
donatien	0:632c9925f013	428	npcb = tcp_alloc(pcb->prio);
donatien	0:632c9925f013	429	/* If a new PCB could not be created (probably due to lack of memory),
donatien	0:632c9925f013	430	we don't do anything, but rely on the sender will retransmit the
donatien	0:632c9925f013	431	SYN at a time when we have more memory available. */
donatien	0:632c9925f013	432	if (npcb == NULL) {
donatien	0:632c9925f013	433	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
donatien	0:632c9925f013	434	TCP_STATS_INC(tcp.memerr);
donatien	0:632c9925f013	435	return ERR_MEM;
donatien	0:632c9925f013	436	}
donatien	0:632c9925f013	437	#if TCP_LISTEN_BACKLOG
donatien	0:632c9925f013	438	pcb->accepts_pending++;
donatien	0:632c9925f013	439	#endif /* TCP_LISTEN_BACKLOG */
donatien	0:632c9925f013	440	/* Set up the new PCB. */
donatien	0:632c9925f013	441	ip_addr_copy(npcb->local_ip, iphdr->dest);
donatien	0:632c9925f013	442	npcb->local_port = pcb->local_port;
donatien	0:632c9925f013	443	ip_addr_copy(npcb->remote_ip, iphdr->src);
donatien	0:632c9925f013	444	npcb->remote_port = tcphdr->src;
donatien	0:632c9925f013	445	npcb->state = SYN_RCVD;
donatien	0:632c9925f013	446	npcb->rcv_nxt = seqno + 1;
donatien	0:632c9925f013	447	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
donatien	0:632c9925f013	448	npcb->snd_wnd = tcphdr->wnd;
donatien	0:632c9925f013	449	npcb->ssthresh = npcb->snd_wnd;
donatien	0:632c9925f013	450	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
donatien	0:632c9925f013	451	npcb->callback_arg = pcb->callback_arg;
donatien	0:632c9925f013	452	#if LWIP_CALLBACK_API
donatien	0:632c9925f013	453	npcb->accept = pcb->accept;
donatien	0:632c9925f013	454	#endif /* LWIP_CALLBACK_API */
donatien	0:632c9925f013	455	/* inherit socket options */
donatien	0:632c9925f013	456	npcb->so_options = pcb->so_options & (SOF_DEBUG\|SOF_DONTROUTE\|SOF_KEEPALIVE\|SOF_OOBINLINE\|SOF_LINGER);
donatien	0:632c9925f013	457	/* Register the new PCB so that we can begin receiving segments
donatien	0:632c9925f013	458	for it. */
donatien	0:632c9925f013	459	TCP_REG(&tcp_active_pcbs, npcb);
donatien	0:632c9925f013	460
donatien	0:632c9925f013	461	/* Parse any options in the SYN. */
donatien	0:632c9925f013	462	tcp_parseopt(npcb);
donatien	0:632c9925f013	463	#if TCP_CALCULATE_EFF_SEND_MSS
donatien	0:632c9925f013	464	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
donatien	0:632c9925f013	465	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
donatien	0:632c9925f013	466
donatien	0:632c9925f013	467	snmp_inc_tcppassiveopens();
donatien	0:632c9925f013	468
donatien	0:632c9925f013	469	/* Send a SYN\|ACK together with the MSS option. */
donatien	0:632c9925f013	470	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
donatien	0:632c9925f013	471	if (rc != ERR_OK) {
donatien	0:632c9925f013	472	tcp_abandon(npcb, 0);
donatien	0:632c9925f013	473	return rc;
donatien	0:632c9925f013	474	}
donatien	0:632c9925f013	475	return tcp_output(npcb);
donatien	0:632c9925f013	476	}
donatien	0:632c9925f013	477	return ERR_OK;
donatien	0:632c9925f013	478	}
donatien	0:632c9925f013	479
donatien	0:632c9925f013	480	/**
donatien	0:632c9925f013	481	* Called by tcp_input() when a segment arrives for a connection in
donatien	0:632c9925f013	482	* TIME_WAIT.
donatien	0:632c9925f013	483	*
donatien	0:632c9925f013	484	* @param pcb the tcp_pcb for which a segment arrived
donatien	0:632c9925f013	485	*
donatien	0:632c9925f013	486	* @note the segment which arrived is saved in global variables, therefore only the pcb
donatien	0:632c9925f013	487	* involved is passed as a parameter to this function
donatien	0:632c9925f013	488	*/
donatien	0:632c9925f013	489	static err_t
donatien	0:632c9925f013	490	tcp_timewait_input(struct tcp_pcb *pcb)
donatien	0:632c9925f013	491	{
donatien	0:632c9925f013	492	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
donatien	0:632c9925f013	493	/* RFC 793 3.9 Event Processing - Segment Arrives:
donatien	0:632c9925f013	494	* - first check sequence number - we skip that one in TIME_WAIT (always
donatien	0:632c9925f013	495	* acceptable since we only send ACKs)
donatien	0:632c9925f013	496	* - second check the RST bit (... return) */
donatien	0:632c9925f013	497	if (flags & TCP_RST) {
donatien	0:632c9925f013	498	return ERR_OK;
donatien	0:632c9925f013	499	}
donatien	0:632c9925f013	500	/* - fourth, check the SYN bit, */
donatien	0:632c9925f013	501	if (flags & TCP_SYN) {
donatien	0:632c9925f013	502	/* If an incoming segment is not acceptable, an acknowledgment
donatien	0:632c9925f013	503	should be sent in reply */
donatien	0:632c9925f013	504	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
donatien	0:632c9925f013	505	/* If the SYN is in the window it is an error, send a reset */
donatien	0:632c9925f013	506	tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
donatien	0:632c9925f013	507	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	508	return ERR_OK;
donatien	0:632c9925f013	509	}
donatien	0:632c9925f013	510	} else if (flags & TCP_FIN) {
donatien	0:632c9925f013	511	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
donatien	0:632c9925f013	512	Restart the 2 MSL time-wait timeout.*/
donatien	0:632c9925f013	513	pcb->tmr = tcp_ticks;
donatien	0:632c9925f013	514	}
donatien	0:632c9925f013	515
donatien	0:632c9925f013	516	if ((tcplen > 0)) {
donatien	0:632c9925f013	517	/* Acknowledge data, FIN or out-of-window SYN */
donatien	0:632c9925f013	518	pcb->flags \|= TF_ACK_NOW;
donatien	0:632c9925f013	519	return tcp_output(pcb);
donatien	0:632c9925f013	520	}
donatien	0:632c9925f013	521	return ERR_OK;
donatien	0:632c9925f013	522	}
donatien	0:632c9925f013	523
donatien	0:632c9925f013	524	/**
donatien	0:632c9925f013	525	* Implements the TCP state machine. Called by tcp_input. In some
donatien	0:632c9925f013	526	* states tcp_receive() is called to receive data. The tcp_seg
donatien	0:632c9925f013	527	* argument will be freed by the caller (tcp_input()) unless the
donatien	0:632c9925f013	528	* recv_data pointer in the pcb is set.
donatien	0:632c9925f013	529	*
donatien	0:632c9925f013	530	* @param pcb the tcp_pcb for which a segment arrived
donatien	0:632c9925f013	531	*
donatien	0:632c9925f013	532	* @note the segment which arrived is saved in global variables, therefore only the pcb
donatien	0:632c9925f013	533	* involved is passed as a parameter to this function
donatien	0:632c9925f013	534	*/
donatien	0:632c9925f013	535	static err_t
donatien	0:632c9925f013	536	tcp_process(struct tcp_pcb *pcb)
donatien	0:632c9925f013	537	{
donatien	0:632c9925f013	538	struct tcp_seg *rseg;
donatien	0:632c9925f013	539	u8_t acceptable = 0;
donatien	0:632c9925f013	540	err_t err;
donatien	0:632c9925f013	541
donatien	0:632c9925f013	542	err = ERR_OK;
donatien	0:632c9925f013	543
donatien	0:632c9925f013	544	/* Process incoming RST segments. */
donatien	0:632c9925f013	545	if (flags & TCP_RST) {
donatien	0:632c9925f013	546	/* First, determine if the reset is acceptable. */
donatien	0:632c9925f013	547	if (pcb->state == SYN_SENT) {
donatien	0:632c9925f013	548	if (ackno == pcb->snd_nxt) {
donatien	0:632c9925f013	549	acceptable = 1;
donatien	0:632c9925f013	550	}
donatien	0:632c9925f013	551	} else {
donatien	0:632c9925f013	552	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
donatien	0:632c9925f013	553	pcb->rcv_nxt+pcb->rcv_wnd)) {
donatien	0:632c9925f013	554	acceptable = 1;
donatien	0:632c9925f013	555	}
donatien	0:632c9925f013	556	}
donatien	0:632c9925f013	557
donatien	0:632c9925f013	558	if (acceptable) {
donatien	0:632c9925f013	559	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
donatien	0:632c9925f013	560	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
donatien	0:632c9925f013	561	recv_flags \|= TF_RESET;
donatien	0:632c9925f013	562	pcb->flags &= ~TF_ACK_DELAY;
donatien	0:632c9925f013	563	return ERR_RST;
donatien	0:632c9925f013	564	} else {
donatien	0:632c9925f013	565	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
donatien	0:632c9925f013	566	seqno, pcb->rcv_nxt));
donatien	0:632c9925f013	567	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
donatien	0:632c9925f013	568	seqno, pcb->rcv_nxt));
donatien	0:632c9925f013	569	return ERR_OK;
donatien	0:632c9925f013	570	}
donatien	0:632c9925f013	571	}
donatien	0:632c9925f013	572
donatien	0:632c9925f013	573	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
donatien	0:632c9925f013	574	/* Cope with new connection attempt after remote end crashed */
donatien	0:632c9925f013	575	tcp_ack_now(pcb);
donatien	0:632c9925f013	576	return ERR_OK;
donatien	0:632c9925f013	577	}
donatien	0:632c9925f013	578
donatien	0:632c9925f013	579	if ((pcb->flags & TF_RXCLOSED) == 0) {
donatien	0:632c9925f013	580	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
donatien	0:632c9925f013	581	pcb->tmr = tcp_ticks;
donatien	0:632c9925f013	582	}
donatien	0:632c9925f013	583	pcb->keep_cnt_sent = 0;
donatien	0:632c9925f013	584
donatien	0:632c9925f013	585	tcp_parseopt(pcb);
donatien	0:632c9925f013	586
donatien	0:632c9925f013	587	/* Do different things depending on the TCP state. */
donatien	0:632c9925f013	588	switch (pcb->state) {
donatien	0:632c9925f013	589	case SYN_SENT:
donatien	0:632c9925f013	590	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
donatien	0:632c9925f013	591	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
donatien	0:632c9925f013	592	/* received SYN ACK with expected sequence number? */
donatien	0:632c9925f013	593	if ((flags & TCP_ACK) && (flags & TCP_SYN)
donatien	0:632c9925f013	594	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
donatien	0:632c9925f013	595	pcb->snd_buf++;
donatien	0:632c9925f013	596	pcb->rcv_nxt = seqno + 1;
donatien	0:632c9925f013	597	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
donatien	0:632c9925f013	598	pcb->lastack = ackno;
donatien	0:632c9925f013	599	pcb->snd_wnd = tcphdr->wnd;
donatien	0:632c9925f013	600	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
donatien	0:632c9925f013	601	pcb->state = ESTABLISHED;
donatien	0:632c9925f013	602
donatien	0:632c9925f013	603	#if TCP_CALCULATE_EFF_SEND_MSS
donatien	0:632c9925f013	604	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
donatien	0:632c9925f013	605	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
donatien	0:632c9925f013	606
donatien	0:632c9925f013	607	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
donatien	0:632c9925f013	608	* but for the default value of pcb->mss) */
donatien	0:632c9925f013	609	pcb->ssthresh = pcb->mss * 10;
donatien	0:632c9925f013	610
donatien	0:632c9925f013	611	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
donatien	0:632c9925f013	612	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
donatien	0:632c9925f013	613	--pcb->snd_queuelen;
donatien	0:632c9925f013	614	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	615	rseg = pcb->unacked;
donatien	0:632c9925f013	616	pcb->unacked = rseg->next;
donatien	0:632c9925f013	617
donatien	0:632c9925f013	618	/* If there's nothing left to acknowledge, stop the retransmit
donatien	0:632c9925f013	619	timer, otherwise reset it to start again */
donatien	0:632c9925f013	620	if(pcb->unacked == NULL)
donatien	0:632c9925f013	621	pcb->rtime = -1;
donatien	0:632c9925f013	622	else {
donatien	0:632c9925f013	623	pcb->rtime = 0;
donatien	0:632c9925f013	624	pcb->nrtx = 0;
donatien	0:632c9925f013	625	}
donatien	0:632c9925f013	626
donatien	0:632c9925f013	627	tcp_seg_free(rseg);
donatien	0:632c9925f013	628
donatien	0:632c9925f013	629	/* Call the user specified function to call when sucessfully
donatien	0:632c9925f013	630	* connected. */
donatien	0:632c9925f013	631	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
donatien	0:632c9925f013	632	if (err == ERR_ABRT) {
donatien	0:632c9925f013	633	return ERR_ABRT;
donatien	0:632c9925f013	634	}
donatien	0:632c9925f013	635	tcp_ack_now(pcb);
donatien	0:632c9925f013	636	}
donatien	0:632c9925f013	637	/* received ACK? possibly a half-open connection */
donatien	0:632c9925f013	638	else if (flags & TCP_ACK) {
donatien	0:632c9925f013	639	/* send a RST to bring the other side in a non-synchronized state. */
donatien	0:632c9925f013	640	tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
donatien	0:632c9925f013	641	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	642	}
donatien	0:632c9925f013	643	break;
donatien	0:632c9925f013	644	case SYN_RCVD:
donatien	0:632c9925f013	645	if (flags & TCP_ACK) {
donatien	0:632c9925f013	646	/* expected ACK number? */
donatien	0:632c9925f013	647	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
donatien	0:632c9925f013	648	u16_t old_cwnd;
donatien	0:632c9925f013	649	pcb->state = ESTABLISHED;
donatien	0:632c9925f013	650	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	651	#if LWIP_CALLBACK_API
donatien	0:632c9925f013	652	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
donatien	0:632c9925f013	653	#endif
donatien	0:632c9925f013	654	/* Call the accept function. */
donatien	0:632c9925f013	655	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
donatien	0:632c9925f013	656	if (err != ERR_OK) {
donatien	0:632c9925f013	657	/* If the accept function returns with an error, we abort
donatien	0:632c9925f013	658	* the connection. */
donatien	0:632c9925f013	659	/* Already aborted? */
donatien	0:632c9925f013	660	if (err != ERR_ABRT) {
donatien	0:632c9925f013	661	tcp_abort(pcb);
donatien	0:632c9925f013	662	}
donatien	0:632c9925f013	663	return ERR_ABRT;
donatien	0:632c9925f013	664	}
donatien	0:632c9925f013	665	old_cwnd = pcb->cwnd;
donatien	0:632c9925f013	666	/* If there was any data contained within this ACK,
donatien	0:632c9925f013	667	* we'd better pass it on to the application as well. */
donatien	0:632c9925f013	668	tcp_receive(pcb);
donatien	0:632c9925f013	669
donatien	0:632c9925f013	670	/* Prevent ACK for SYN to generate a sent event */
donatien	0:632c9925f013	671	if (pcb->acked != 0) {
donatien	0:632c9925f013	672	pcb->acked--;
donatien	0:632c9925f013	673	}
donatien	0:632c9925f013	674
donatien	0:632c9925f013	675	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
donatien	0:632c9925f013	676
donatien	0:632c9925f013	677	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	678	tcp_ack_now(pcb);
donatien	0:632c9925f013	679	pcb->state = CLOSE_WAIT;
donatien	0:632c9925f013	680	}
donatien	0:632c9925f013	681	} else {
donatien	0:632c9925f013	682	/* incorrect ACK number, send RST */
donatien	0:632c9925f013	683	tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
donatien	0:632c9925f013	684	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	685	}
donatien	0:632c9925f013	686	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
donatien	0:632c9925f013	687	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
donatien	0:632c9925f013	688	tcp_rexmit(pcb);
donatien	0:632c9925f013	689	}
donatien	0:632c9925f013	690	break;
donatien	0:632c9925f013	691	case CLOSE_WAIT:
donatien	0:632c9925f013	692	/* FALLTHROUGH */
donatien	0:632c9925f013	693	case ESTABLISHED:
donatien	0:632c9925f013	694	tcp_receive(pcb);
donatien	0:632c9925f013	695	if (recv_flags & TF_GOT_FIN) { /* passive close */
donatien	0:632c9925f013	696	tcp_ack_now(pcb);
donatien	0:632c9925f013	697	pcb->state = CLOSE_WAIT;
donatien	0:632c9925f013	698	}
donatien	0:632c9925f013	699	break;
donatien	0:632c9925f013	700	case FIN_WAIT_1:
donatien	0:632c9925f013	701	tcp_receive(pcb);
donatien	0:632c9925f013	702	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	703	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
donatien	0:632c9925f013	704	LWIP_DEBUGF(TCP_DEBUG,
donatien	0:632c9925f013	705	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	706	tcp_ack_now(pcb);
donatien	0:632c9925f013	707	tcp_pcb_purge(pcb);
donatien	0:632c9925f013	708	TCP_RMV(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	709	pcb->state = TIME_WAIT;
donatien	0:632c9925f013	710	TCP_REG(&tcp_tw_pcbs, pcb);
donatien	0:632c9925f013	711	} else {
donatien	0:632c9925f013	712	tcp_ack_now(pcb);
donatien	0:632c9925f013	713	pcb->state = CLOSING;
donatien	0:632c9925f013	714	}
donatien	0:632c9925f013	715	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
donatien	0:632c9925f013	716	pcb->state = FIN_WAIT_2;
donatien	0:632c9925f013	717	}
donatien	0:632c9925f013	718	break;
donatien	0:632c9925f013	719	case FIN_WAIT_2:
donatien	0:632c9925f013	720	tcp_receive(pcb);
donatien	0:632c9925f013	721	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	722	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	723	tcp_ack_now(pcb);
donatien	0:632c9925f013	724	tcp_pcb_purge(pcb);
donatien	0:632c9925f013	725	TCP_RMV(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	726	pcb->state = TIME_WAIT;
donatien	0:632c9925f013	727	TCP_REG(&tcp_tw_pcbs, pcb);
donatien	0:632c9925f013	728	}
donatien	0:632c9925f013	729	break;
donatien	0:632c9925f013	730	case CLOSING:
donatien	0:632c9925f013	731	tcp_receive(pcb);
donatien	0:632c9925f013	732	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
donatien	0:632c9925f013	733	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	734	tcp_pcb_purge(pcb);
donatien	0:632c9925f013	735	TCP_RMV(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	736	pcb->state = TIME_WAIT;
donatien	0:632c9925f013	737	TCP_REG(&tcp_tw_pcbs, pcb);
donatien	0:632c9925f013	738	}
donatien	0:632c9925f013	739	break;
donatien	0:632c9925f013	740	case LAST_ACK:
donatien	0:632c9925f013	741	tcp_receive(pcb);
donatien	0:632c9925f013	742	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
donatien	0:632c9925f013	743	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	744	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
donatien	0:632c9925f013	745	recv_flags \|= TF_CLOSED;
donatien	0:632c9925f013	746	}
donatien	0:632c9925f013	747	break;
donatien	0:632c9925f013	748	default:
donatien	0:632c9925f013	749	break;
donatien	0:632c9925f013	750	}
donatien	0:632c9925f013	751	return ERR_OK;
donatien	0:632c9925f013	752	}
donatien	0:632c9925f013	753
donatien	0:632c9925f013	754	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	755	/**
donatien	0:632c9925f013	756	* Insert segment into the list (segments covered with new one will be deleted)
donatien	0:632c9925f013	757	*
donatien	0:632c9925f013	758	* Called from tcp_receive()
donatien	0:632c9925f013	759	*/
donatien	0:632c9925f013	760	static void
donatien	0:632c9925f013	761	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
donatien	0:632c9925f013	762	{
donatien	0:632c9925f013	763	struct tcp_seg *old_seg;
donatien	0:632c9925f013	764
donatien	0:632c9925f013	765	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	766	/* received segment overlaps all following segments */
donatien	0:632c9925f013	767	tcp_segs_free(next);
donatien	0:632c9925f013	768	next = NULL;
donatien	0:632c9925f013	769	}
donatien	0:632c9925f013	770	else {
donatien	0:632c9925f013	771	/* delete some following segments
donatien	0:632c9925f013	772	oos queue may have segments with FIN flag */
donatien	0:632c9925f013	773	while (next &&
donatien	0:632c9925f013	774	TCP_SEQ_GEQ((seqno + cseg->len),
donatien	0:632c9925f013	775	(next->tcphdr->seqno + next->len))) {
donatien	0:632c9925f013	776	/* cseg with FIN already processed */
donatien	0:632c9925f013	777	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	778	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
donatien	0:632c9925f013	779	}
donatien	0:632c9925f013	780	old_seg = next;
donatien	0:632c9925f013	781	next = next->next;
donatien	0:632c9925f013	782	tcp_seg_free(old_seg);
donatien	0:632c9925f013	783	}
donatien	0:632c9925f013	784	if (next &&
donatien	0:632c9925f013	785	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
donatien	0:632c9925f013	786	/* We need to trim the incoming segment. */
donatien	0:632c9925f013	787	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
donatien	0:632c9925f013	788	pbuf_realloc(cseg->p, cseg->len);
donatien	0:632c9925f013	789	}
donatien	0:632c9925f013	790	}
donatien	0:632c9925f013	791	cseg->next = next;
donatien	0:632c9925f013	792	}
donatien	0:632c9925f013	793	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	794
donatien	0:632c9925f013	795	/**
donatien	0:632c9925f013	796	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
donatien	0:632c9925f013	797	* data, and if so frees the memory of the buffered data. Next, is places the
donatien	0:632c9925f013	798	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
donatien	0:632c9925f013	799	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
donatien	0:632c9925f013	800	* i it has been removed from the buffer.
donatien	0:632c9925f013	801	*
donatien	0:632c9925f013	802	* If the incoming segment constitutes an ACK for a segment that was used for RTT
donatien	0:632c9925f013	803	* estimation, the RTT is estimated here as well.
donatien	0:632c9925f013	804	*
donatien	0:632c9925f013	805	* Called from tcp_process().
donatien	0:632c9925f013	806	*/
donatien	0:632c9925f013	807	static void
donatien	0:632c9925f013	808	tcp_receive(struct tcp_pcb *pcb)
donatien	0:632c9925f013	809	{
donatien	0:632c9925f013	810	struct tcp_seg *next;
donatien	0:632c9925f013	811	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	812	struct tcp_seg prev, cseg;
donatien	0:632c9925f013	813	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	814	struct pbuf *p;
donatien	0:632c9925f013	815	s32_t off;
donatien	0:632c9925f013	816	s16_t m;
donatien	0:632c9925f013	817	u32_t right_wnd_edge;
donatien	0:632c9925f013	818	u16_t new_tot_len;
donatien	0:632c9925f013	819	int found_dupack = 0;
donatien	0:632c9925f013	820
donatien	0:632c9925f013	821	if (flags & TCP_ACK) {
donatien	0:632c9925f013	822	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
donatien	0:632c9925f013	823
donatien	0:632c9925f013	824	/* Update window. */
donatien	0:632c9925f013	825	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
donatien	0:632c9925f013	826	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
donatien	0:632c9925f013	827	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
donatien	0:632c9925f013	828	pcb->snd_wnd = tcphdr->wnd;
donatien	0:632c9925f013	829	pcb->snd_wl1 = seqno;
donatien	0:632c9925f013	830	pcb->snd_wl2 = ackno;
donatien	0:632c9925f013	831	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
donatien	0:632c9925f013	832	pcb->persist_backoff = 0;
donatien	0:632c9925f013	833	}
donatien	0:632c9925f013	834	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
donatien	0:632c9925f013	835	#if TCP_WND_DEBUG
donatien	0:632c9925f013	836	} else {
donatien	0:632c9925f013	837	if (pcb->snd_wnd != tcphdr->wnd) {
donatien	0:632c9925f013	838	LWIP_DEBUGF(TCP_WND_DEBUG,
donatien	0:632c9925f013	839	("tcp_receive: no window update lastack %"U32_F" ackno %"
donatien	0:632c9925f013	840	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
donatien	0:632c9925f013	841	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
donatien	0:632c9925f013	842	}
donatien	0:632c9925f013	843	#endif /* TCP_WND_DEBUG */
donatien	0:632c9925f013	844	}
donatien	0:632c9925f013	845
donatien	0:632c9925f013	846	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
donatien	0:632c9925f013	847	* duplicate ack if:
donatien	0:632c9925f013	848	* 1) It doesn't ACK new data
donatien	0:632c9925f013	849	* 2) length of received packet is zero (i.e. no payload)
donatien	0:632c9925f013	850	* 3) the advertised window hasn't changed
donatien	0:632c9925f013	851	* 4) There is outstanding unacknowledged data (retransmission timer running)
donatien	0:632c9925f013	852	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
donatien	0:632c9925f013	853	*
donatien	0:632c9925f013	854	* If it passes all five, should process as a dupack:
donatien	0:632c9925f013	855	* a) dupacks < 3: do nothing
donatien	0:632c9925f013	856	* b) dupacks == 3: fast retransmit
donatien	0:632c9925f013	857	* c) dupacks > 3: increase cwnd
donatien	0:632c9925f013	858	*
donatien	0:632c9925f013	859	* If it only passes 1-3, should reset dupack counter (and add to
donatien	0:632c9925f013	860	* stats, which we don't do in lwIP)
donatien	0:632c9925f013	861	*
donatien	0:632c9925f013	862	* If it only passes 1, should reset dupack counter
donatien	0:632c9925f013	863	*
donatien	0:632c9925f013	864	*/
donatien	0:632c9925f013	865
donatien	0:632c9925f013	866	/* Clause 1 */
donatien	0:632c9925f013	867	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
donatien	0:632c9925f013	868	pcb->acked = 0;
donatien	0:632c9925f013	869	/* Clause 2 */
donatien	0:632c9925f013	870	if (tcplen == 0) {
donatien	0:632c9925f013	871	/* Clause 3 */
donatien	0:632c9925f013	872	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
donatien	0:632c9925f013	873	/* Clause 4 */
donatien	0:632c9925f013	874	if (pcb->rtime >= 0) {
donatien	0:632c9925f013	875	/* Clause 5 */
donatien	0:632c9925f013	876	if (pcb->lastack == ackno) {
donatien	0:632c9925f013	877	found_dupack = 1;
donatien	0:632c9925f013	878	if (pcb->dupacks + 1 > pcb->dupacks)
donatien	0:632c9925f013	879	++pcb->dupacks;
donatien	0:632c9925f013	880	if (pcb->dupacks > 3) {
donatien	0:632c9925f013	881	/* Inflate the congestion window, but not if it means that
donatien	0:632c9925f013	882	the value overflows. */
donatien	0:632c9925f013	883	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
donatien	0:632c9925f013	884	pcb->cwnd += pcb->mss;
donatien	0:632c9925f013	885	}
donatien	0:632c9925f013	886	} else if (pcb->dupacks == 3) {
donatien	0:632c9925f013	887	/* Do fast retransmit */
donatien	0:632c9925f013	888	tcp_rexmit_fast(pcb);
donatien	0:632c9925f013	889	}
donatien	0:632c9925f013	890	}
donatien	0:632c9925f013	891	}
donatien	0:632c9925f013	892	}
donatien	0:632c9925f013	893	}
donatien	0:632c9925f013	894	/* If Clause (1) or more is true, but not a duplicate ack, reset
donatien	0:632c9925f013	895	* count of consecutive duplicate acks */
donatien	0:632c9925f013	896	if (!found_dupack) {
donatien	0:632c9925f013	897	pcb->dupacks = 0;
donatien	0:632c9925f013	898	}
donatien	0:632c9925f013	899	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
donatien	0:632c9925f013	900	/* We come here when the ACK acknowledges new data. */
donatien	0:632c9925f013	901
donatien	0:632c9925f013	902	/* Reset the "IN Fast Retransmit" flag, since we are no longer
donatien	0:632c9925f013	903	in fast retransmit. Also reset the congestion window to the
donatien	0:632c9925f013	904	slow start threshold. */
donatien	0:632c9925f013	905	if (pcb->flags & TF_INFR) {
donatien	0:632c9925f013	906	pcb->flags &= ~TF_INFR;
donatien	0:632c9925f013	907	pcb->cwnd = pcb->ssthresh;
donatien	0:632c9925f013	908	}
donatien	0:632c9925f013	909
donatien	0:632c9925f013	910	/* Reset the number of retransmissions. */
donatien	0:632c9925f013	911	pcb->nrtx = 0;
donatien	0:632c9925f013	912
donatien	0:632c9925f013	913	/* Reset the retransmission time-out. */
donatien	0:632c9925f013	914	pcb->rto = (pcb->sa >> 3) + pcb->sv;
donatien	0:632c9925f013	915
donatien	0:632c9925f013	916	/* Update the send buffer space. Diff between the two can never exceed 64K? */
donatien	0:632c9925f013	917	pcb->acked = (u16_t)(ackno - pcb->lastack);
donatien	0:632c9925f013	918
donatien	0:632c9925f013	919	pcb->snd_buf += pcb->acked;
donatien	0:632c9925f013	920
donatien	0:632c9925f013	921	/* Reset the fast retransmit variables. */
donatien	0:632c9925f013	922	pcb->dupacks = 0;
donatien	0:632c9925f013	923	pcb->lastack = ackno;
donatien	0:632c9925f013	924
donatien	0:632c9925f013	925	/* Update the congestion control variables (cwnd and
donatien	0:632c9925f013	926	ssthresh). */
donatien	0:632c9925f013	927	if (pcb->state >= ESTABLISHED) {
donatien	0:632c9925f013	928	if (pcb->cwnd < pcb->ssthresh) {
donatien	0:632c9925f013	929	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
donatien	0:632c9925f013	930	pcb->cwnd += pcb->mss;
donatien	0:632c9925f013	931	}
donatien	0:632c9925f013	932	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
donatien	0:632c9925f013	933	} else {
donatien	0:632c9925f013	934	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
donatien	0:632c9925f013	935	if (new_cwnd > pcb->cwnd) {
donatien	0:632c9925f013	936	pcb->cwnd = new_cwnd;
donatien	0:632c9925f013	937	}
donatien	0:632c9925f013	938	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
donatien	0:632c9925f013	939	}
donatien	0:632c9925f013	940	}
donatien	0:632c9925f013	941	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
donatien	0:632c9925f013	942	ackno,
donatien	0:632c9925f013	943	pcb->unacked != NULL?
donatien	0:632c9925f013	944	ntohl(pcb->unacked->tcphdr->seqno): 0,
donatien	0:632c9925f013	945	pcb->unacked != NULL?
donatien	0:632c9925f013	946	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
donatien	0:632c9925f013	947
donatien	0:632c9925f013	948	/* Remove segment from the unacknowledged list if the incoming
donatien	0:632c9925f013	949	ACK acknowlegdes them. */
donatien	0:632c9925f013	950	while (pcb->unacked != NULL &&
donatien	0:632c9925f013	951	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
donatien	0:632c9925f013	952	TCP_TCPLEN(pcb->unacked), ackno)) {
donatien	0:632c9925f013	953	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
donatien	0:632c9925f013	954	ntohl(pcb->unacked->tcphdr->seqno),
donatien	0:632c9925f013	955	ntohl(pcb->unacked->tcphdr->seqno) +
donatien	0:632c9925f013	956	TCP_TCPLEN(pcb->unacked)));
donatien	0:632c9925f013	957
donatien	0:632c9925f013	958	next = pcb->unacked;
donatien	0:632c9925f013	959	pcb->unacked = pcb->unacked->next;
donatien	0:632c9925f013	960
donatien	0:632c9925f013	961	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	962	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
donatien	0:632c9925f013	963	/* Prevent ACK for FIN to generate a sent event */
donatien	0:632c9925f013	964	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
donatien	0:632c9925f013	965	pcb->acked--;
donatien	0:632c9925f013	966	}
donatien	0:632c9925f013	967
donatien	0:632c9925f013	968	pcb->snd_queuelen -= pbuf_clen(next->p);
donatien	0:632c9925f013	969	tcp_seg_free(next);
donatien	0:632c9925f013	970
donatien	0:632c9925f013	971	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	972	if (pcb->snd_queuelen != 0) {
donatien	0:632c9925f013	973	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
donatien	0:632c9925f013	974	pcb->unsent != NULL);
donatien	0:632c9925f013	975	}
donatien	0:632c9925f013	976	}
donatien	0:632c9925f013	977
donatien	0:632c9925f013	978	/* If there's nothing left to acknowledge, stop the retransmit
donatien	0:632c9925f013	979	timer, otherwise reset it to start again */
donatien	0:632c9925f013	980	if(pcb->unacked == NULL)
donatien	0:632c9925f013	981	pcb->rtime = -1;
donatien	0:632c9925f013	982	else
donatien	0:632c9925f013	983	pcb->rtime = 0;
donatien	0:632c9925f013	984
donatien	0:632c9925f013	985	pcb->polltmr = 0;
donatien	0:632c9925f013	986	} else {
donatien	0:632c9925f013	987	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
donatien	0:632c9925f013	988	pcb->acked = 0;
donatien	0:632c9925f013	989	}
donatien	0:632c9925f013	990
donatien	0:632c9925f013	991	/* We go through the ->unsent list to see if any of the segments
donatien	0:632c9925f013	992	on the list are acknowledged by the ACK. This may seem
donatien	0:632c9925f013	993	strange since an "unsent" segment shouldn't be acked. The
donatien	0:632c9925f013	994	rationale is that lwIP puts all outstanding segments on the
donatien	0:632c9925f013	995	->unsent list after a retransmission, so these segments may
donatien	0:632c9925f013	996	in fact have been sent once. */
donatien	0:632c9925f013	997	while (pcb->unsent != NULL &&
donatien	0:632c9925f013	998	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
donatien	0:632c9925f013	999	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
donatien	0:632c9925f013	1000	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
donatien	0:632c9925f013	1001	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
donatien	0:632c9925f013	1002	TCP_TCPLEN(pcb->unsent)));
donatien	0:632c9925f013	1003
donatien	0:632c9925f013	1004	next = pcb->unsent;
donatien	0:632c9925f013	1005	pcb->unsent = pcb->unsent->next;
donatien	0:632c9925f013	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	1007	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
donatien	0:632c9925f013	1008	/* Prevent ACK for FIN to generate a sent event */
donatien	0:632c9925f013	1009	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
donatien	0:632c9925f013	1010	pcb->acked--;
donatien	0:632c9925f013	1011	}
donatien	0:632c9925f013	1012	pcb->snd_queuelen -= pbuf_clen(next->p);
donatien	0:632c9925f013	1013	tcp_seg_free(next);
donatien	0:632c9925f013	1014	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	1015	if (pcb->snd_queuelen != 0) {
donatien	0:632c9925f013	1016	LWIP_ASSERT("tcp_receive: valid queue length",
donatien	0:632c9925f013	1017	pcb->unacked != NULL \|\| pcb->unsent != NULL);
donatien	0:632c9925f013	1018	}
donatien	0:632c9925f013	1019	}
donatien	0:632c9925f013	1020	/* End of ACK for new data processing. */
donatien	0:632c9925f013	1021
donatien	0:632c9925f013	1022	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
donatien	0:632c9925f013	1023	pcb->rttest, pcb->rtseq, ackno));
donatien	0:632c9925f013	1024
donatien	0:632c9925f013	1025	/* RTT estimation calculations. This is done by checking if the
donatien	0:632c9925f013	1026	incoming segment acknowledges the segment we use to take a
donatien	0:632c9925f013	1027	round-trip time measurement. */
donatien	0:632c9925f013	1028	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
donatien	0:632c9925f013	1029	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
donatien	0:632c9925f013	1030	and a round-trip shouldn't be that long... */
donatien	0:632c9925f013	1031	m = (s16_t)(tcp_ticks - pcb->rttest);
donatien	0:632c9925f013	1032
donatien	0:632c9925f013	1033	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
donatien	0:632c9925f013	1034	m, m * TCP_SLOW_INTERVAL));
donatien	0:632c9925f013	1035
donatien	0:632c9925f013	1036	/* This is taken directly from VJs original code in his paper */
donatien	0:632c9925f013	1037	m = m - (pcb->sa >> 3);
donatien	0:632c9925f013	1038	pcb->sa += m;
donatien	0:632c9925f013	1039	if (m < 0) {
donatien	0:632c9925f013	1040	m = -m;
donatien	0:632c9925f013	1041	}
donatien	0:632c9925f013	1042	m = m - (pcb->sv >> 2);
donatien	0:632c9925f013	1043	pcb->sv += m;
donatien	0:632c9925f013	1044	pcb->rto = (pcb->sa >> 3) + pcb->sv;
donatien	0:632c9925f013	1045
donatien	0:632c9925f013	1046	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
donatien	0:632c9925f013	1047	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
donatien	0:632c9925f013	1048
donatien	0:632c9925f013	1049	pcb->rttest = 0;
donatien	0:632c9925f013	1050	}
donatien	0:632c9925f013	1051	}
donatien	0:632c9925f013	1052
donatien	0:632c9925f013	1053	/* If the incoming segment contains data, we must process it
donatien	0:632c9925f013	1054	further. */
donatien	0:632c9925f013	1055	if (tcplen > 0) {
donatien	0:632c9925f013	1056	/* This code basically does three things:
donatien	0:632c9925f013	1057
donatien	0:632c9925f013	1058	+) If the incoming segment contains data that is the next
donatien	0:632c9925f013	1059	in-sequence data, this data is passed to the application. This
donatien	0:632c9925f013	1060	might involve trimming the first edge of the data. The rcv_nxt
donatien	0:632c9925f013	1061	variable and the advertised window are adjusted.
donatien	0:632c9925f013	1062
donatien	0:632c9925f013	1063	+) If the incoming segment has data that is above the next
donatien	0:632c9925f013	1064	sequence number expected (->rcv_nxt), the segment is placed on
donatien	0:632c9925f013	1065	the ->ooseq queue. This is done by finding the appropriate
donatien	0:632c9925f013	1066	place in the ->ooseq queue (which is ordered by sequence
donatien	0:632c9925f013	1067	number) and trim the segment in both ends if needed. An
donatien	0:632c9925f013	1068	immediate ACK is sent to indicate that we received an
donatien	0:632c9925f013	1069	out-of-sequence segment.
donatien	0:632c9925f013	1070
donatien	0:632c9925f013	1071	+) Finally, we check if the first segment on the ->ooseq queue
donatien	0:632c9925f013	1072	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
donatien	0:632c9925f013	1073	rcv_nxt > ooseq->seqno, we must trim the first edge of the
donatien	0:632c9925f013	1074	segment on ->ooseq before we adjust rcv_nxt. The data in the
donatien	0:632c9925f013	1075	segments that are now on sequence are chained onto the
donatien	0:632c9925f013	1076	incoming segment so that we only need to call the application
donatien	0:632c9925f013	1077	once.
donatien	0:632c9925f013	1078	*/
donatien	0:632c9925f013	1079
donatien	0:632c9925f013	1080	/* First, we check if we must trim the first edge. We have to do
donatien	0:632c9925f013	1081	this if the sequence number of the incoming segment is less
donatien	0:632c9925f013	1082	than rcv_nxt, and the sequence number plus the length of the
donatien	0:632c9925f013	1083	segment is larger than rcv_nxt. */
donatien	0:632c9925f013	1084	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
donatien	0:632c9925f013	1085	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
donatien	0:632c9925f013	1086	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
donatien	0:632c9925f013	1087	/* Trimming the first edge is done by pushing the payload
donatien	0:632c9925f013	1088	pointer in the pbuf downwards. This is somewhat tricky since
donatien	0:632c9925f013	1089	we do not want to discard the full contents of the pbuf up to
donatien	0:632c9925f013	1090	the new starting point of the data since we have to keep the
donatien	0:632c9925f013	1091	TCP header which is present in the first pbuf in the chain.
donatien	0:632c9925f013	1092
donatien	0:632c9925f013	1093	What is done is really quite a nasty hack: the first pbuf in
donatien	0:632c9925f013	1094	the pbuf chain is pointed to by inseg.p. Since we need to be
donatien	0:632c9925f013	1095	able to deallocate the whole pbuf, we cannot change this
donatien	0:632c9925f013	1096	inseg.p pointer to point to any of the later pbufs in the
donatien	0:632c9925f013	1097	chain. Instead, we point the ->payload pointer in the first
donatien	0:632c9925f013	1098	pbuf to data in one of the later pbufs. We also set the
donatien	0:632c9925f013	1099	inseg.data pointer to point to the right place. This way, the
donatien	0:632c9925f013	1100	->p pointer will still point to the first pbuf, but the
donatien	0:632c9925f013	1101	->p->payload pointer will point to data in another pbuf.
donatien	0:632c9925f013	1102
donatien	0:632c9925f013	1103	After we are done with adjusting the pbuf pointers we must
donatien	0:632c9925f013	1104	adjust the ->data pointer in the seg and the segment
donatien	0:632c9925f013	1105	length.*/
donatien	0:632c9925f013	1106
donatien	0:632c9925f013	1107	off = pcb->rcv_nxt - seqno;
donatien	0:632c9925f013	1108	p = inseg.p;
donatien	0:632c9925f013	1109	LWIP_ASSERT("inseg.p != NULL", inseg.p);
donatien	0:632c9925f013	1110	LWIP_ASSERT("insane offset!", (off < 0x7fff));
donatien	0:632c9925f013	1111	if (inseg.p->len < off) {
donatien	0:632c9925f013	1112	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
donatien	0:632c9925f013	1113	new_tot_len = (u16_t)(inseg.p->tot_len - off);
donatien	0:632c9925f013	1114	while (p->len < off) {
donatien	0:632c9925f013	1115	off -= p->len;
donatien	0:632c9925f013	1116	/* KJM following line changed (with addition of new_tot_len var)
donatien	0:632c9925f013	1117	to fix bug #9076
donatien	0:632c9925f013	1118	inseg.p->tot_len -= p->len; */
donatien	0:632c9925f013	1119	p->tot_len = new_tot_len;
donatien	0:632c9925f013	1120	p->len = 0;
donatien	0:632c9925f013	1121	p = p->next;
donatien	0:632c9925f013	1122	}
donatien	0:632c9925f013	1123	if(pbuf_header(p, (s16_t)-off)) {
donatien	0:632c9925f013	1124	/* Do we need to cope with this failing? Assert for now */
donatien	0:632c9925f013	1125	LWIP_ASSERT("pbuf_header failed", 0);
donatien	0:632c9925f013	1126	}
donatien	0:632c9925f013	1127	} else {
donatien	0:632c9925f013	1128	if(pbuf_header(inseg.p, (s16_t)-off)) {
donatien	0:632c9925f013	1129	/* Do we need to cope with this failing? Assert for now */
donatien	0:632c9925f013	1130	LWIP_ASSERT("pbuf_header failed", 0);
donatien	0:632c9925f013	1131	}
donatien	0:632c9925f013	1132	}
donatien	0:632c9925f013	1133	/* KJM following line changed to use p->payload rather than inseg->p->payload
donatien	0:632c9925f013	1134	to fix bug #9076 */
donatien	0:632c9925f013	1135	inseg.dataptr = p->payload;
donatien	0:632c9925f013	1136	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
donatien	0:632c9925f013	1137	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
donatien	0:632c9925f013	1138	}
donatien	0:632c9925f013	1139	else {
donatien	0:632c9925f013	1140	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
donatien	0:632c9925f013	1141	/* the whole segment is < rcv_nxt */
donatien	0:632c9925f013	1142	/* must be a duplicate of a packet that has already been correctly handled */
donatien	0:632c9925f013	1143
donatien	0:632c9925f013	1144	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
donatien	0:632c9925f013	1145	tcp_ack_now(pcb);
donatien	0:632c9925f013	1146	}
donatien	0:632c9925f013	1147	}
donatien	0:632c9925f013	1148
donatien	0:632c9925f013	1149	/* The sequence number must be within the window (above rcv_nxt
donatien	0:632c9925f013	1150	and below rcv_nxt + rcv_wnd) in order to be further
donatien	0:632c9925f013	1151	processed. */
donatien	0:632c9925f013	1152	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
donatien	0:632c9925f013	1153	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
donatien	0:632c9925f013	1154	if (pcb->rcv_nxt == seqno) {
donatien	0:632c9925f013	1155	/* The incoming segment is the next in sequence. We check if
donatien	0:632c9925f013	1156	we have to trim the end of the segment and update rcv_nxt
donatien	0:632c9925f013	1157	and pass the data to the application. */
donatien	0:632c9925f013	1158	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1159
donatien	0:632c9925f013	1160	if (tcplen > pcb->rcv_wnd) {
donatien	0:632c9925f013	1161	LWIP_DEBUGF(TCP_INPUT_DEBUG,
donatien	0:632c9925f013	1162	("tcp_receive: other end overran receive window"
donatien	0:632c9925f013	1163	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
donatien	0:632c9925f013	1164	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
donatien	0:632c9925f013	1165	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1166	/* Must remove the FIN from the header as we're trimming
donatien	0:632c9925f013	1167	* that byte of sequence-space from the packet */
donatien	0:632c9925f013	1168	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
donatien	0:632c9925f013	1169	}
donatien	0:632c9925f013	1170	/* Adjust length of segment to fit in the window. */
donatien	0:632c9925f013	1171	inseg.len = pcb->rcv_wnd;
donatien	0:632c9925f013	1172	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
donatien	0:632c9925f013	1173	inseg.len -= 1;
donatien	0:632c9925f013	1174	}
donatien	0:632c9925f013	1175	pbuf_realloc(inseg.p, inseg.len);
donatien	0:632c9925f013	1176	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1177	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
donatien	0:632c9925f013	1178	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
donatien	0:632c9925f013	1179	}
donatien	0:632c9925f013	1180	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	1181	/* Received in-sequence data, adjust ooseq data if:
donatien	0:632c9925f013	1182	- FIN has been received or
donatien	0:632c9925f013	1183	- inseq overlaps with ooseq */
donatien	0:632c9925f013	1184	if (pcb->ooseq != NULL) {
donatien	0:632c9925f013	1185	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1186	LWIP_DEBUGF(TCP_INPUT_DEBUG,
donatien	0:632c9925f013	1187	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
donatien	0:632c9925f013	1188	/* Received in-order FIN means anything that was received
donatien	0:632c9925f013	1189	* out of order must now have been received in-order, so
donatien	0:632c9925f013	1190	* bin the ooseq queue */
donatien	0:632c9925f013	1191	while (pcb->ooseq != NULL) {
donatien	0:632c9925f013	1192	struct tcp_seg *old_ooseq = pcb->ooseq;
donatien	0:632c9925f013	1193	pcb->ooseq = pcb->ooseq->next;
donatien	0:632c9925f013	1194	tcp_seg_free(old_ooseq);
donatien	0:632c9925f013	1195	}
donatien	0:632c9925f013	1196	}
donatien	0:632c9925f013	1197	else {
donatien	0:632c9925f013	1198	next = pcb->ooseq;
donatien	0:632c9925f013	1199	/* Remove all segments on ooseq that are covered by inseg already.
donatien	0:632c9925f013	1200	* FIN is copied from ooseq to inseg if present. */
donatien	0:632c9925f013	1201	while (next &&
donatien	0:632c9925f013	1202	TCP_SEQ_GEQ(seqno + tcplen,
donatien	0:632c9925f013	1203	next->tcphdr->seqno + next->len)) {
donatien	0:632c9925f013	1204	/* inseg cannot have FIN here (already processed above) */
donatien	0:632c9925f013	1205	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
donatien	0:632c9925f013	1206	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
donatien	0:632c9925f013	1207	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
donatien	0:632c9925f013	1208	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1209	}
donatien	0:632c9925f013	1210	prev = next;
donatien	0:632c9925f013	1211	next = next->next;
donatien	0:632c9925f013	1212	tcp_seg_free(prev);
donatien	0:632c9925f013	1213	}
donatien	0:632c9925f013	1214	/* Now trim right side of inseg if it overlaps with the first
donatien	0:632c9925f013	1215	* segment on ooseq */
donatien	0:632c9925f013	1216	if (next &&
donatien	0:632c9925f013	1217	TCP_SEQ_GT(seqno + tcplen,
donatien	0:632c9925f013	1218	next->tcphdr->seqno)) {
donatien	0:632c9925f013	1219	/* inseg cannot have FIN here (already processed above) */
donatien	0:632c9925f013	1220	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
donatien	0:632c9925f013	1221	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
donatien	0:632c9925f013	1222	inseg.len -= 1;
donatien	0:632c9925f013	1223	}
donatien	0:632c9925f013	1224	pbuf_realloc(inseg.p, inseg.len);
donatien	0:632c9925f013	1225	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1226	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
donatien	0:632c9925f013	1227	(seqno + tcplen) == next->tcphdr->seqno);
donatien	0:632c9925f013	1228	}
donatien	0:632c9925f013	1229	pcb->ooseq = next;
donatien	0:632c9925f013	1230	}
donatien	0:632c9925f013	1231	}
donatien	0:632c9925f013	1232	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	1233
donatien	0:632c9925f013	1234	pcb->rcv_nxt = seqno + tcplen;
donatien	0:632c9925f013	1235
donatien	0:632c9925f013	1236	/* Update the receiver's (our) window. */
donatien	0:632c9925f013	1237	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
donatien	0:632c9925f013	1238	pcb->rcv_wnd -= tcplen;
donatien	0:632c9925f013	1239
donatien	0:632c9925f013	1240	tcp_update_rcv_ann_wnd(pcb);
donatien	0:632c9925f013	1241
donatien	0:632c9925f013	1242	/* If there is data in the segment, we make preparations to
donatien	0:632c9925f013	1243	pass this up to the application. The ->recv_data variable
donatien	0:632c9925f013	1244	is used for holding the pbuf that goes to the
donatien	0:632c9925f013	1245	application. The code for reassembling out-of-sequence data
donatien	0:632c9925f013	1246	chains its data on this pbuf as well.
donatien	0:632c9925f013	1247
donatien	0:632c9925f013	1248	If the segment was a FIN, we set the TF_GOT_FIN flag that will
donatien	0:632c9925f013	1249	be used to indicate to the application that the remote side has
donatien	0:632c9925f013	1250	closed its end of the connection. */
donatien	0:632c9925f013	1251	if (inseg.p->tot_len > 0) {
donatien	0:632c9925f013	1252	recv_data = inseg.p;
donatien	0:632c9925f013	1253	/* Since this pbuf now is the responsibility of the
donatien	0:632c9925f013	1254	application, we delete our reference to it so that we won't
donatien	0:632c9925f013	1255	(mistakingly) deallocate it. */
donatien	0:632c9925f013	1256	inseg.p = NULL;
donatien	0:632c9925f013	1257	}
donatien	0:632c9925f013	1258	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1259	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
donatien	0:632c9925f013	1260	recv_flags \|= TF_GOT_FIN;
donatien	0:632c9925f013	1261	}
donatien	0:632c9925f013	1262
donatien	0:632c9925f013	1263	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	1264	/* We now check if we have segments on the ->ooseq queue that
donatien	0:632c9925f013	1265	are now in sequence. */
donatien	0:632c9925f013	1266	while (pcb->ooseq != NULL &&
donatien	0:632c9925f013	1267	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
donatien	0:632c9925f013	1268
donatien	0:632c9925f013	1269	cseg = pcb->ooseq;
donatien	0:632c9925f013	1270	seqno = pcb->ooseq->tcphdr->seqno;
donatien	0:632c9925f013	1271
donatien	0:632c9925f013	1272	pcb->rcv_nxt += TCP_TCPLEN(cseg);
donatien	0:632c9925f013	1273	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
donatien	0:632c9925f013	1274	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
donatien	0:632c9925f013	1275	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
donatien	0:632c9925f013	1276
donatien	0:632c9925f013	1277	tcp_update_rcv_ann_wnd(pcb);
donatien	0:632c9925f013	1278
donatien	0:632c9925f013	1279	if (cseg->p->tot_len > 0) {
donatien	0:632c9925f013	1280	/* Chain this pbuf onto the pbuf that we will pass to
donatien	0:632c9925f013	1281	the application. */
donatien	0:632c9925f013	1282	if (recv_data) {
donatien	0:632c9925f013	1283	pbuf_cat(recv_data, cseg->p);
donatien	0:632c9925f013	1284	} else {
donatien	0:632c9925f013	1285	recv_data = cseg->p;
donatien	0:632c9925f013	1286	}
donatien	0:632c9925f013	1287	cseg->p = NULL;
donatien	0:632c9925f013	1288	}
donatien	0:632c9925f013	1289	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1290	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
donatien	0:632c9925f013	1291	recv_flags \|= TF_GOT_FIN;
donatien	0:632c9925f013	1292	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
donatien	0:632c9925f013	1293	pcb->state = CLOSE_WAIT;
donatien	0:632c9925f013	1294	}
donatien	0:632c9925f013	1295	}
donatien	0:632c9925f013	1296
donatien	0:632c9925f013	1297	pcb->ooseq = cseg->next;
donatien	0:632c9925f013	1298	tcp_seg_free(cseg);
donatien	0:632c9925f013	1299	}
donatien	0:632c9925f013	1300	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	1301
donatien	0:632c9925f013	1302
donatien	0:632c9925f013	1303	/* Acknowledge the segment(s). */
donatien	0:632c9925f013	1304	tcp_ack(pcb);
donatien	0:632c9925f013	1305
donatien	0:632c9925f013	1306	} else {
donatien	0:632c9925f013	1307	/* We get here if the incoming segment is out-of-sequence. */
donatien	0:632c9925f013	1308	tcp_send_empty_ack(pcb);
donatien	0:632c9925f013	1309	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	1310	/* We queue the segment on the ->ooseq queue. */
donatien	0:632c9925f013	1311	if (pcb->ooseq == NULL) {
donatien	0:632c9925f013	1312	pcb->ooseq = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1313	} else {
donatien	0:632c9925f013	1314	/* If the queue is not empty, we walk through the queue and
donatien	0:632c9925f013	1315	try to find a place where the sequence number of the
donatien	0:632c9925f013	1316	incoming segment is between the sequence numbers of the
donatien	0:632c9925f013	1317	previous and the next segment on the ->ooseq queue. That is
donatien	0:632c9925f013	1318	the place where we put the incoming segment. If needed, we
donatien	0:632c9925f013	1319	trim the second edges of the previous and the incoming
donatien	0:632c9925f013	1320	segment so that it will fit into the sequence.
donatien	0:632c9925f013	1321
donatien	0:632c9925f013	1322	If the incoming segment has the same sequence number as a
donatien	0:632c9925f013	1323	segment on the ->ooseq queue, we discard the segment that
donatien	0:632c9925f013	1324	contains less data. */
donatien	0:632c9925f013	1325
donatien	0:632c9925f013	1326	prev = NULL;
donatien	0:632c9925f013	1327	for(next = pcb->ooseq; next != NULL; next = next->next) {
donatien	0:632c9925f013	1328	if (seqno == next->tcphdr->seqno) {
donatien	0:632c9925f013	1329	/* The sequence number of the incoming segment is the
donatien	0:632c9925f013	1330	same as the sequence number of the segment on
donatien	0:632c9925f013	1331	->ooseq. We check the lengths to see which one to
donatien	0:632c9925f013	1332	discard. */
donatien	0:632c9925f013	1333	if (inseg.len > next->len) {
donatien	0:632c9925f013	1334	/* The incoming segment is larger than the old
donatien	0:632c9925f013	1335	segment. We replace some segments with the new
donatien	0:632c9925f013	1336	one. */
donatien	0:632c9925f013	1337	cseg = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1338	if (cseg != NULL) {
donatien	0:632c9925f013	1339	if (prev != NULL) {
donatien	0:632c9925f013	1340	prev->next = cseg;
donatien	0:632c9925f013	1341	} else {
donatien	0:632c9925f013	1342	pcb->ooseq = cseg;
donatien	0:632c9925f013	1343	}
donatien	0:632c9925f013	1344	tcp_oos_insert_segment(cseg, next);
donatien	0:632c9925f013	1345	}
donatien	0:632c9925f013	1346	break;
donatien	0:632c9925f013	1347	} else {
donatien	0:632c9925f013	1348	/* Either the lenghts are the same or the incoming
donatien	0:632c9925f013	1349	segment was smaller than the old one; in either
donatien	0:632c9925f013	1350	case, we ditch the incoming segment. */
donatien	0:632c9925f013	1351	break;
donatien	0:632c9925f013	1352	}
donatien	0:632c9925f013	1353	} else {
donatien	0:632c9925f013	1354	if (prev == NULL) {
donatien	0:632c9925f013	1355	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
donatien	0:632c9925f013	1356	/* The sequence number of the incoming segment is lower
donatien	0:632c9925f013	1357	than the sequence number of the first segment on the
donatien	0:632c9925f013	1358	queue. We put the incoming segment first on the
donatien	0:632c9925f013	1359	queue. */
donatien	0:632c9925f013	1360	cseg = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1361	if (cseg != NULL) {
donatien	0:632c9925f013	1362	pcb->ooseq = cseg;
donatien	0:632c9925f013	1363	tcp_oos_insert_segment(cseg, next);
donatien	0:632c9925f013	1364	}
donatien	0:632c9925f013	1365	break;
donatien	0:632c9925f013	1366	}
donatien	0:632c9925f013	1367	} else {
donatien	0:632c9925f013	1368	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
donatien	0:632c9925f013	1369	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
donatien	0:632c9925f013	1370	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
donatien	0:632c9925f013	1371	/* The sequence number of the incoming segment is in
donatien	0:632c9925f013	1372	between the sequence numbers of the previous and
donatien	0:632c9925f013	1373	the next segment on ->ooseq. We trim trim the previous
donatien	0:632c9925f013	1374	segment, delete next segments that included in received segment
donatien	0:632c9925f013	1375	and trim received, if needed. */
donatien	0:632c9925f013	1376	cseg = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1377	if (cseg != NULL) {
donatien	0:632c9925f013	1378	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
donatien	0:632c9925f013	1379	/* We need to trim the prev segment. */
donatien	0:632c9925f013	1380	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
donatien	0:632c9925f013	1381	pbuf_realloc(prev->p, prev->len);
donatien	0:632c9925f013	1382	}
donatien	0:632c9925f013	1383	prev->next = cseg;
donatien	0:632c9925f013	1384	tcp_oos_insert_segment(cseg, next);
donatien	0:632c9925f013	1385	}
donatien	0:632c9925f013	1386	break;
donatien	0:632c9925f013	1387	}
donatien	0:632c9925f013	1388	}
donatien	0:632c9925f013	1389	/* If the "next" segment is the last segment on the
donatien	0:632c9925f013	1390	ooseq queue, we add the incoming segment to the end
donatien	0:632c9925f013	1391	of the list. */
donatien	0:632c9925f013	1392	if (next->next == NULL &&
donatien	0:632c9925f013	1393	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
donatien	0:632c9925f013	1394	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1395	/* segment "next" already contains all data */
donatien	0:632c9925f013	1396	break;
donatien	0:632c9925f013	1397	}
donatien	0:632c9925f013	1398	next->next = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1399	if (next->next != NULL) {
donatien	0:632c9925f013	1400	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
donatien	0:632c9925f013	1401	/* We need to trim the last segment. */
donatien	0:632c9925f013	1402	next->len = (u16_t)(seqno - next->tcphdr->seqno);
donatien	0:632c9925f013	1403	pbuf_realloc(next->p, next->len);
donatien	0:632c9925f013	1404	}
donatien	0:632c9925f013	1405	}
donatien	0:632c9925f013	1406	break;
donatien	0:632c9925f013	1407	}
donatien	0:632c9925f013	1408	}
donatien	0:632c9925f013	1409	prev = next;
donatien	0:632c9925f013	1410	}
donatien	0:632c9925f013	1411	}
donatien	0:632c9925f013	1412	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	1413
donatien	0:632c9925f013	1414	}
donatien	0:632c9925f013	1415	} else {
donatien	0:632c9925f013	1416	/* The incoming segment is not withing the window. */
donatien	0:632c9925f013	1417	tcp_send_empty_ack(pcb);
donatien	0:632c9925f013	1418	}
donatien	0:632c9925f013	1419	} else {
donatien	0:632c9925f013	1420	/* Segments with length 0 is taken care of here. Segments that
donatien	0:632c9925f013	1421	fall out of the window are ACKed. */
donatien	0:632c9925f013	1422	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
donatien	0:632c9925f013	1423	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
donatien	0:632c9925f013	1424	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
donatien	0:632c9925f013	1425	tcp_ack_now(pcb);
donatien	0:632c9925f013	1426	}
donatien	0:632c9925f013	1427	}
donatien	0:632c9925f013	1428	}
donatien	0:632c9925f013	1429
donatien	0:632c9925f013	1430	/**
donatien	0:632c9925f013	1431	* Parses the options contained in the incoming segment.
donatien	0:632c9925f013	1432	*
donatien	0:632c9925f013	1433	* Called from tcp_listen_input() and tcp_process().
donatien	0:632c9925f013	1434	* Currently, only the MSS option is supported!
donatien	0:632c9925f013	1435	*
donatien	0:632c9925f013	1436	* @param pcb the tcp_pcb for which a segment arrived
donatien	0:632c9925f013	1437	*/
donatien	0:632c9925f013	1438	static void
donatien	0:632c9925f013	1439	tcp_parseopt(struct tcp_pcb *pcb)
donatien	0:632c9925f013	1440	{
donatien	0:632c9925f013	1441	u16_t c, max_c;
donatien	0:632c9925f013	1442	u16_t mss;
donatien	0:632c9925f013	1443	u8_t *opts, opt;
donatien	0:632c9925f013	1444	#if LWIP_TCP_TIMESTAMPS
donatien	0:632c9925f013	1445	u32_t tsval;
donatien	0:632c9925f013	1446	#endif
donatien	0:632c9925f013	1447
donatien	0:632c9925f013	1448	opts = (u8_t *)tcphdr + TCP_HLEN;
donatien	0:632c9925f013	1449
donatien	0:632c9925f013	1450	/* Parse the TCP MSS option, if present. */
donatien	0:632c9925f013	1451	if(TCPH_HDRLEN(tcphdr) > 0x5) {
donatien	0:632c9925f013	1452	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
donatien	0:632c9925f013	1453	for (c = 0; c < max_c; ) {
donatien	0:632c9925f013	1454	opt = opts[c];
donatien	0:632c9925f013	1455	switch (opt) {
donatien	0:632c9925f013	1456	case 0x00:
donatien	0:632c9925f013	1457	/* End of options. */
donatien	0:632c9925f013	1458	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
donatien	0:632c9925f013	1459	return;
donatien	0:632c9925f013	1460	case 0x01:
donatien	0:632c9925f013	1461	/* NOP option. */
donatien	0:632c9925f013	1462	++c;
donatien	0:632c9925f013	1463	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
donatien	0:632c9925f013	1464	break;
donatien	0:632c9925f013	1465	case 0x02:
donatien	0:632c9925f013	1466	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
donatien	0:632c9925f013	1467	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
donatien	0:632c9925f013	1468	/* Bad length */
donatien	0:632c9925f013	1469	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
donatien	0:632c9925f013	1470	return;
donatien	0:632c9925f013	1471	}
donatien	0:632c9925f013	1472	/* An MSS option with the right option length. */
donatien	0:632c9925f013	1473	mss = (opts[c + 2] << 8) \| opts[c + 3];
donatien	0:632c9925f013	1474	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
donatien	0:632c9925f013	1475	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
donatien	0:632c9925f013	1476	/* Advance to next option */
donatien	0:632c9925f013	1477	c += 0x04;
donatien	0:632c9925f013	1478	break;
donatien	0:632c9925f013	1479	#if LWIP_TCP_TIMESTAMPS
donatien	0:632c9925f013	1480	case 0x08:
donatien	0:632c9925f013	1481	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
donatien	0:632c9925f013	1482	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
donatien	0:632c9925f013	1483	/* Bad length */
donatien	0:632c9925f013	1484	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
donatien	0:632c9925f013	1485	return;
donatien	0:632c9925f013	1486	}
donatien	0:632c9925f013	1487	/* TCP timestamp option with valid length */
donatien	0:632c9925f013	1488	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
donatien	0:632c9925f013	1489	(opts[c+4] << 16) \| (opts[c+5] << 24);
donatien	0:632c9925f013	1490	if (flags & TCP_SYN) {
donatien	0:632c9925f013	1491	pcb->ts_recent = ntohl(tsval);
donatien	0:632c9925f013	1492	pcb->flags \|= TF_TIMESTAMP;
donatien	0:632c9925f013	1493	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
donatien	0:632c9925f013	1494	pcb->ts_recent = ntohl(tsval);
donatien	0:632c9925f013	1495	}
donatien	0:632c9925f013	1496	/* Advance to next option */
donatien	0:632c9925f013	1497	c += 0x0A;
donatien	0:632c9925f013	1498	break;
donatien	0:632c9925f013	1499	#endif
donatien	0:632c9925f013	1500	default:
donatien	0:632c9925f013	1501	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
donatien	0:632c9925f013	1502	if (opts[c + 1] == 0) {
donatien	0:632c9925f013	1503	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
donatien	0:632c9925f013	1504	/* If the length field is zero, the options are malformed
donatien	0:632c9925f013	1505	and we don't process them further. */
donatien	0:632c9925f013	1506	return;
donatien	0:632c9925f013	1507	}
donatien	0:632c9925f013	1508	/* All other options have a length field, so that we easily
donatien	0:632c9925f013	1509	can skip past them. */
donatien	0:632c9925f013	1510	c += opts[c + 1];
donatien	0:632c9925f013	1511	}
donatien	0:632c9925f013	1512	}
donatien	0:632c9925f013	1513	}
donatien	0:632c9925f013	1514	}
donatien	0:632c9925f013	1515
donatien	0:632c9925f013	1516	#endif /* LWIP_TCP */

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Type:	Program
Created:	11 Jun 2010
Imports:	2654
Forks:	0
Commits:	12
Dependents:	3
Dependencies:	0
Followers:	13

This repository is Public (Unlisted).

lwip/core/tcp_in.c@0:632c9925f013, 2010-06-11 (annotated)

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