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NetStack/lwip/core/tcp_in.c@0:616601bde9fb, 2012-02-23 (annotated)

Committer:: AdamGreen
Date:: Thu Feb 23 21:38:39 2012 +0000
Revision:: 0:616601bde9fb

Who changed what in which revision?

User	Revision	Line number	New contents of line
AdamGreen	0:616601bde9fb	1	/**
AdamGreen	0:616601bde9fb	2	* @file
AdamGreen	0:616601bde9fb	3	* Transmission Control Protocol, incoming traffic
AdamGreen	0:616601bde9fb	4	*
AdamGreen	0:616601bde9fb	5	* The input processing functions of the TCP layer.
AdamGreen	0:616601bde9fb	6	*
AdamGreen	0:616601bde9fb	7	* These functions are generally called in the order (ip_input() ->)
AdamGreen	0:616601bde9fb	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
AdamGreen	0:616601bde9fb	9	*
AdamGreen	0:616601bde9fb	10	*/
AdamGreen	0:616601bde9fb	11
AdamGreen	0:616601bde9fb	12	/*
AdamGreen	0:616601bde9fb	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
AdamGreen	0:616601bde9fb	14	* All rights reserved.
AdamGreen	0:616601bde9fb	15	*
AdamGreen	0:616601bde9fb	16	* Redistribution and use in source and binary forms, with or without modification,
AdamGreen	0:616601bde9fb	17	* are permitted provided that the following conditions are met:
AdamGreen	0:616601bde9fb	18	*
AdamGreen	0:616601bde9fb	19	* 1. Redistributions of source code must retain the above copyright notice,
AdamGreen	0:616601bde9fb	20	* this list of conditions and the following disclaimer.
AdamGreen	0:616601bde9fb	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
AdamGreen	0:616601bde9fb	22	* this list of conditions and the following disclaimer in the documentation
AdamGreen	0:616601bde9fb	23	* and/or other materials provided with the distribution.
AdamGreen	0:616601bde9fb	24	* 3. The name of the author may not be used to endorse or promote products
AdamGreen	0:616601bde9fb	25	* derived from this software without specific prior written permission.
AdamGreen	0:616601bde9fb	26	*
AdamGreen	0:616601bde9fb	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
AdamGreen	0:616601bde9fb	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
AdamGreen	0:616601bde9fb	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
AdamGreen	0:616601bde9fb	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
AdamGreen	0:616601bde9fb	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
AdamGreen	0:616601bde9fb	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
AdamGreen	0:616601bde9fb	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
AdamGreen	0:616601bde9fb	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
AdamGreen	0:616601bde9fb	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
AdamGreen	0:616601bde9fb	36	* OF SUCH DAMAGE.
AdamGreen	0:616601bde9fb	37	*
AdamGreen	0:616601bde9fb	38	* This file is part of the lwIP TCP/IP stack.
AdamGreen	0:616601bde9fb	39	*
AdamGreen	0:616601bde9fb	40	* Author: Adam Dunkels <adam@sics.se>
AdamGreen	0:616601bde9fb	41	*
AdamGreen	0:616601bde9fb	42	*/
AdamGreen	0:616601bde9fb	43
AdamGreen	0:616601bde9fb	44	#include "lwip/opt.h"
AdamGreen	0:616601bde9fb	45
AdamGreen	0:616601bde9fb	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
AdamGreen	0:616601bde9fb	47
AdamGreen	0:616601bde9fb	48	#include "lwip/tcp_impl.h"
AdamGreen	0:616601bde9fb	49	#include "lwip/def.h"
AdamGreen	0:616601bde9fb	50	#include "lwip/ip_addr.h"
AdamGreen	0:616601bde9fb	51	#include "lwip/netif.h"
AdamGreen	0:616601bde9fb	52	#include "lwip/mem.h"
AdamGreen	0:616601bde9fb	53	#include "lwip/memp.h"
AdamGreen	0:616601bde9fb	54	#include "lwip/inet_chksum.h"
AdamGreen	0:616601bde9fb	55	#include "lwip/stats.h"
AdamGreen	0:616601bde9fb	56	#include "lwip/snmp.h"
AdamGreen	0:616601bde9fb	57	#include "arch/perf.h"
AdamGreen	0:616601bde9fb	58
AdamGreen	0:616601bde9fb	59	/* These variables are global to all functions involved in the input
AdamGreen	0:616601bde9fb	60	processing of TCP segments. They are set by the tcp_input()
AdamGreen	0:616601bde9fb	61	function. */
AdamGreen	0:616601bde9fb	62	static struct tcp_seg inseg;
AdamGreen	0:616601bde9fb	63	static struct tcp_hdr *tcphdr;
AdamGreen	0:616601bde9fb	64	static struct ip_hdr *iphdr;
AdamGreen	0:616601bde9fb	65	static u32_t seqno, ackno;
AdamGreen	0:616601bde9fb	66	static u8_t flags;
AdamGreen	0:616601bde9fb	67	static u16_t tcplen;
AdamGreen	0:616601bde9fb	68
AdamGreen	0:616601bde9fb	69	static u8_t recv_flags;
AdamGreen	0:616601bde9fb	70	static struct pbuf *recv_data;
AdamGreen	0:616601bde9fb	71
AdamGreen	0:616601bde9fb	72	struct tcp_pcb *tcp_input_pcb;
AdamGreen	0:616601bde9fb	73
AdamGreen	0:616601bde9fb	74	/* Forward declarations. */
AdamGreen	0:616601bde9fb	75	static err_t tcp_process(struct tcp_pcb *pcb);
AdamGreen	0:616601bde9fb	76	static void tcp_receive(struct tcp_pcb *pcb);
AdamGreen	0:616601bde9fb	77	static void tcp_parseopt(struct tcp_pcb *pcb);
AdamGreen	0:616601bde9fb	78
AdamGreen	0:616601bde9fb	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
AdamGreen	0:616601bde9fb	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
AdamGreen	0:616601bde9fb	81
AdamGreen	0:616601bde9fb	82	/**
AdamGreen	0:616601bde9fb	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
AdamGreen	0:616601bde9fb	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
AdamGreen	0:616601bde9fb	85	* the TCP finite state machine. This function is called by the IP layer (in
AdamGreen	0:616601bde9fb	86	* ip_input()).
AdamGreen	0:616601bde9fb	87	*
AdamGreen	0:616601bde9fb	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
AdamGreen	0:616601bde9fb	89	* @param inp network interface on which this segment was received
AdamGreen	0:616601bde9fb	90	*/
AdamGreen	0:616601bde9fb	91	void
AdamGreen	0:616601bde9fb	92	tcp_input(struct pbuf p, struct netif inp)
AdamGreen	0:616601bde9fb	93	{
AdamGreen	0:616601bde9fb	94	struct tcp_pcb pcb, prev;
AdamGreen	0:616601bde9fb	95	struct tcp_pcb_listen *lpcb;
AdamGreen	0:616601bde9fb	96	#if SO_REUSE
AdamGreen	0:616601bde9fb	97	struct tcp_pcb *lpcb_prev = NULL;
AdamGreen	0:616601bde9fb	98	struct tcp_pcb_listen *lpcb_any = NULL;
AdamGreen	0:616601bde9fb	99	#endif /* SO_REUSE */
AdamGreen	0:616601bde9fb	100	u8_t hdrlen;
AdamGreen	0:616601bde9fb	101	err_t err;
AdamGreen	0:616601bde9fb	102
AdamGreen	0:616601bde9fb	103	PERF_START;
AdamGreen	0:616601bde9fb	104
AdamGreen	0:616601bde9fb	105	TCP_STATS_INC(tcp.recv);
AdamGreen	0:616601bde9fb	106	snmp_inc_tcpinsegs();
AdamGreen	0:616601bde9fb	107
AdamGreen	0:616601bde9fb	108	iphdr = (struct ip_hdr *)p->payload;
AdamGreen	0:616601bde9fb	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
AdamGreen	0:616601bde9fb	110
AdamGreen	0:616601bde9fb	111	#if TCP_INPUT_DEBUG
AdamGreen	0:616601bde9fb	112	tcp_debug_print(tcphdr);
AdamGreen	0:616601bde9fb	113	#endif
AdamGreen	0:616601bde9fb	114
AdamGreen	0:616601bde9fb	115	/* remove header from payload */
AdamGreen	0:616601bde9fb	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
AdamGreen	0:616601bde9fb	117	/* drop short packets */
AdamGreen	0:616601bde9fb	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
AdamGreen	0:616601bde9fb	119	TCP_STATS_INC(tcp.lenerr);
AdamGreen	0:616601bde9fb	120	TCP_STATS_INC(tcp.drop);
AdamGreen	0:616601bde9fb	121	snmp_inc_tcpinerrs();
AdamGreen	0:616601bde9fb	122	pbuf_free(p);
AdamGreen	0:616601bde9fb	123	return;
AdamGreen	0:616601bde9fb	124	}
AdamGreen	0:616601bde9fb	125
AdamGreen	0:616601bde9fb	126	/* Don't even process incoming broadcasts/multicasts. */
AdamGreen	0:616601bde9fb	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
AdamGreen	0:616601bde9fb	128	ip_addr_ismulticast(&current_iphdr_dest)) {
AdamGreen	0:616601bde9fb	129	TCP_STATS_INC(tcp.proterr);
AdamGreen	0:616601bde9fb	130	TCP_STATS_INC(tcp.drop);
AdamGreen	0:616601bde9fb	131	snmp_inc_tcpinerrs();
AdamGreen	0:616601bde9fb	132	pbuf_free(p);
AdamGreen	0:616601bde9fb	133	return;
AdamGreen	0:616601bde9fb	134	}
AdamGreen	0:616601bde9fb	135
AdamGreen	0:616601bde9fb	136	#if CHECKSUM_CHECK_TCP
AdamGreen	0:616601bde9fb	137	/* Verify TCP checksum. */
AdamGreen	0:616601bde9fb	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
AdamGreen	0:616601bde9fb	139	IP_PROTO_TCP, p->tot_len) != 0) {
AdamGreen	0:616601bde9fb	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
AdamGreen	0:616601bde9fb	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
AdamGreen	0:616601bde9fb	142	IP_PROTO_TCP, p->tot_len)));
AdamGreen	0:616601bde9fb	143	#if TCP_DEBUG
AdamGreen	0:616601bde9fb	144	tcp_debug_print(tcphdr);
AdamGreen	0:616601bde9fb	145	#endif /* TCP_DEBUG */
AdamGreen	0:616601bde9fb	146	TCP_STATS_INC(tcp.chkerr);
AdamGreen	0:616601bde9fb	147	TCP_STATS_INC(tcp.drop);
AdamGreen	0:616601bde9fb	148	snmp_inc_tcpinerrs();
AdamGreen	0:616601bde9fb	149	pbuf_free(p);
AdamGreen	0:616601bde9fb	150	return;
AdamGreen	0:616601bde9fb	151	}
AdamGreen	0:616601bde9fb	152	#endif
AdamGreen	0:616601bde9fb	153
AdamGreen	0:616601bde9fb	154	/* Move the payload pointer in the pbuf so that it points to the
AdamGreen	0:616601bde9fb	155	TCP data instead of the TCP header. */
AdamGreen	0:616601bde9fb	156	hdrlen = TCPH_HDRLEN(tcphdr);
AdamGreen	0:616601bde9fb	157	if(pbuf_header(p, -(hdrlen * 4))){
AdamGreen	0:616601bde9fb	158	/* drop short packets */
AdamGreen	0:616601bde9fb	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
AdamGreen	0:616601bde9fb	160	TCP_STATS_INC(tcp.lenerr);
AdamGreen	0:616601bde9fb	161	TCP_STATS_INC(tcp.drop);
AdamGreen	0:616601bde9fb	162	snmp_inc_tcpinerrs();
AdamGreen	0:616601bde9fb	163	pbuf_free(p);
AdamGreen	0:616601bde9fb	164	return;
AdamGreen	0:616601bde9fb	165	}
AdamGreen	0:616601bde9fb	166
AdamGreen	0:616601bde9fb	167	/* Convert fields in TCP header to host byte order. */
AdamGreen	0:616601bde9fb	168	tcphdr->src = ntohs(tcphdr->src);
AdamGreen	0:616601bde9fb	169	tcphdr->dest = ntohs(tcphdr->dest);
AdamGreen	0:616601bde9fb	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
AdamGreen	0:616601bde9fb	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
AdamGreen	0:616601bde9fb	172	tcphdr->wnd = ntohs(tcphdr->wnd);
AdamGreen	0:616601bde9fb	173
AdamGreen	0:616601bde9fb	174	flags = TCPH_FLAGS(tcphdr);
AdamGreen	0:616601bde9fb	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
AdamGreen	0:616601bde9fb	176
AdamGreen	0:616601bde9fb	177	/* Demultiplex an incoming segment. First, we check if it is destined
AdamGreen	0:616601bde9fb	178	for an active connection. */
AdamGreen	0:616601bde9fb	179	prev = NULL;
AdamGreen	0:616601bde9fb	180
AdamGreen	0:616601bde9fb	181
AdamGreen	0:616601bde9fb	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
AdamGreen	0:616601bde9fb	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
AdamGreen	0:616601bde9fb	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
AdamGreen	0:616601bde9fb	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
AdamGreen	0:616601bde9fb	186	if (pcb->remote_port == tcphdr->src &&
AdamGreen	0:616601bde9fb	187	pcb->local_port == tcphdr->dest &&
AdamGreen	0:616601bde9fb	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
AdamGreen	0:616601bde9fb	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
AdamGreen	0:616601bde9fb	190
AdamGreen	0:616601bde9fb	191	/* Move this PCB to the front of the list so that subsequent
AdamGreen	0:616601bde9fb	192	lookups will be faster (we exploit locality in TCP segment
AdamGreen	0:616601bde9fb	193	arrivals). */
AdamGreen	0:616601bde9fb	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
AdamGreen	0:616601bde9fb	195	if (prev != NULL) {
AdamGreen	0:616601bde9fb	196	prev->next = pcb->next;
AdamGreen	0:616601bde9fb	197	pcb->next = tcp_active_pcbs;
AdamGreen	0:616601bde9fb	198	tcp_active_pcbs = pcb;
AdamGreen	0:616601bde9fb	199	}
AdamGreen	0:616601bde9fb	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
AdamGreen	0:616601bde9fb	201	break;
AdamGreen	0:616601bde9fb	202	}
AdamGreen	0:616601bde9fb	203	prev = pcb;
AdamGreen	0:616601bde9fb	204	}
AdamGreen	0:616601bde9fb	205
AdamGreen	0:616601bde9fb	206	if (pcb == NULL) {
AdamGreen	0:616601bde9fb	207	/* If it did not go to an active connection, we check the connections
AdamGreen	0:616601bde9fb	208	in the TIME-WAIT state. */
AdamGreen	0:616601bde9fb	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
AdamGreen	0:616601bde9fb	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
AdamGreen	0:616601bde9fb	211	if (pcb->remote_port == tcphdr->src &&
AdamGreen	0:616601bde9fb	212	pcb->local_port == tcphdr->dest &&
AdamGreen	0:616601bde9fb	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
AdamGreen	0:616601bde9fb	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
AdamGreen	0:616601bde9fb	215	/* We don't really care enough to move this PCB to the front
AdamGreen	0:616601bde9fb	216	of the list since we are not very likely to receive that
AdamGreen	0:616601bde9fb	217	many segments for connections in TIME-WAIT. */
AdamGreen	0:616601bde9fb	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
AdamGreen	0:616601bde9fb	219	tcp_timewait_input(pcb);
AdamGreen	0:616601bde9fb	220	pbuf_free(p);
AdamGreen	0:616601bde9fb	221	return;
AdamGreen	0:616601bde9fb	222	}
AdamGreen	0:616601bde9fb	223	}
AdamGreen	0:616601bde9fb	224
AdamGreen	0:616601bde9fb	225	/* Finally, if we still did not get a match, we check all PCBs that
AdamGreen	0:616601bde9fb	226	are LISTENing for incoming connections. */
AdamGreen	0:616601bde9fb	227	prev = NULL;
AdamGreen	0:616601bde9fb	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
AdamGreen	0:616601bde9fb	229	if (lpcb->local_port == tcphdr->dest) {
AdamGreen	0:616601bde9fb	230	#if SO_REUSE
AdamGreen	0:616601bde9fb	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
AdamGreen	0:616601bde9fb	232	/* found an exact match */
AdamGreen	0:616601bde9fb	233	break;
AdamGreen	0:616601bde9fb	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
AdamGreen	0:616601bde9fb	235	/* found an ANY-match */
AdamGreen	0:616601bde9fb	236	lpcb_any = lpcb;
AdamGreen	0:616601bde9fb	237	lpcb_prev = prev;
AdamGreen	0:616601bde9fb	238	}
AdamGreen	0:616601bde9fb	239	#else /* SO_REUSE */
AdamGreen	0:616601bde9fb	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
AdamGreen	0:616601bde9fb	241	ip_addr_isany(&(lpcb->local_ip))) {
AdamGreen	0:616601bde9fb	242	/* found a match */
AdamGreen	0:616601bde9fb	243	break;
AdamGreen	0:616601bde9fb	244	}
AdamGreen	0:616601bde9fb	245	#endif /* SO_REUSE */
AdamGreen	0:616601bde9fb	246	}
AdamGreen	0:616601bde9fb	247	prev = (struct tcp_pcb *)lpcb;
AdamGreen	0:616601bde9fb	248	}
AdamGreen	0:616601bde9fb	249	#if SO_REUSE
AdamGreen	0:616601bde9fb	250	/* first try specific local IP */
AdamGreen	0:616601bde9fb	251	if (lpcb == NULL) {
AdamGreen	0:616601bde9fb	252	/* only pass to ANY if no specific local IP has been found */
AdamGreen	0:616601bde9fb	253	lpcb = lpcb_any;
AdamGreen	0:616601bde9fb	254	prev = lpcb_prev;
AdamGreen	0:616601bde9fb	255	}
AdamGreen	0:616601bde9fb	256	#endif /* SO_REUSE */
AdamGreen	0:616601bde9fb	257	if (lpcb != NULL) {
AdamGreen	0:616601bde9fb	258	/* Move this PCB to the front of the list so that subsequent
AdamGreen	0:616601bde9fb	259	lookups will be faster (we exploit locality in TCP segment
AdamGreen	0:616601bde9fb	260	arrivals). */
AdamGreen	0:616601bde9fb	261	if (prev != NULL) {
AdamGreen	0:616601bde9fb	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
AdamGreen	0:616601bde9fb	263	/* our successor is the remainder of the listening list */
AdamGreen	0:616601bde9fb	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
AdamGreen	0:616601bde9fb	265	/* put this listening pcb at the head of the listening list */
AdamGreen	0:616601bde9fb	266	tcp_listen_pcbs.listen_pcbs = lpcb;
AdamGreen	0:616601bde9fb	267	}
AdamGreen	0:616601bde9fb	268
AdamGreen	0:616601bde9fb	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
AdamGreen	0:616601bde9fb	270	tcp_listen_input(lpcb);
AdamGreen	0:616601bde9fb	271	pbuf_free(p);
AdamGreen	0:616601bde9fb	272	return;
AdamGreen	0:616601bde9fb	273	}
AdamGreen	0:616601bde9fb	274	}
AdamGreen	0:616601bde9fb	275
AdamGreen	0:616601bde9fb	276	#if TCP_INPUT_DEBUG
AdamGreen	0:616601bde9fb	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
AdamGreen	0:616601bde9fb	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
AdamGreen	0:616601bde9fb	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
AdamGreen	0:616601bde9fb	280	#endif /* TCP_INPUT_DEBUG */
AdamGreen	0:616601bde9fb	281
AdamGreen	0:616601bde9fb	282
AdamGreen	0:616601bde9fb	283	if (pcb != NULL) {
AdamGreen	0:616601bde9fb	284	/* The incoming segment belongs to a connection. */
AdamGreen	0:616601bde9fb	285	#if TCP_INPUT_DEBUG
AdamGreen	0:616601bde9fb	286	#if TCP_DEBUG
AdamGreen	0:616601bde9fb	287	tcp_debug_print_state(pcb->state);
AdamGreen	0:616601bde9fb	288	#endif /* TCP_DEBUG */
AdamGreen	0:616601bde9fb	289	#endif /* TCP_INPUT_DEBUG */
AdamGreen	0:616601bde9fb	290
AdamGreen	0:616601bde9fb	291	/* Set up a tcp_seg structure. */
AdamGreen	0:616601bde9fb	292	inseg.next = NULL;
AdamGreen	0:616601bde9fb	293	inseg.len = p->tot_len;
AdamGreen	0:616601bde9fb	294	inseg.dataptr = p->payload;
AdamGreen	0:616601bde9fb	295	inseg.p = p;
AdamGreen	0:616601bde9fb	296	inseg.tcphdr = tcphdr;
AdamGreen	0:616601bde9fb	297
AdamGreen	0:616601bde9fb	298	recv_data = NULL;
AdamGreen	0:616601bde9fb	299	recv_flags = 0;
AdamGreen	0:616601bde9fb	300
AdamGreen	0:616601bde9fb	301	/* If there is data which was previously "refused" by upper layer */
AdamGreen	0:616601bde9fb	302	if (pcb->refused_data != NULL) {
AdamGreen	0:616601bde9fb	303	/* Notify again application with data previously received. */
AdamGreen	0:616601bde9fb	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
AdamGreen	0:616601bde9fb	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
AdamGreen	0:616601bde9fb	306	if (err == ERR_OK) {
AdamGreen	0:616601bde9fb	307	pcb->refused_data = NULL;
AdamGreen	0:616601bde9fb	308	} else {
AdamGreen	0:616601bde9fb	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
AdamGreen	0:616601bde9fb	310	/* drop incoming packets, because pcb is "full" */
AdamGreen	0:616601bde9fb	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
AdamGreen	0:616601bde9fb	312	TCP_STATS_INC(tcp.drop);
AdamGreen	0:616601bde9fb	313	snmp_inc_tcpinerrs();
AdamGreen	0:616601bde9fb	314	pbuf_free(p);
AdamGreen	0:616601bde9fb	315	return;
AdamGreen	0:616601bde9fb	316	}
AdamGreen	0:616601bde9fb	317	}
AdamGreen	0:616601bde9fb	318	tcp_input_pcb = pcb;
AdamGreen	0:616601bde9fb	319	err = tcp_process(pcb);
AdamGreen	0:616601bde9fb	320	/* A return value of ERR_ABRT means that tcp_abort() was called
AdamGreen	0:616601bde9fb	321	and that the pcb has been freed. If so, we don't do anything. */
AdamGreen	0:616601bde9fb	322	if (err != ERR_ABRT) {
AdamGreen	0:616601bde9fb	323	if (recv_flags & TF_RESET) {
AdamGreen	0:616601bde9fb	324	/* TF_RESET means that the connection was reset by the other
AdamGreen	0:616601bde9fb	325	end. We then call the error callback to inform the
AdamGreen	0:616601bde9fb	326	application that the connection is dead before we
AdamGreen	0:616601bde9fb	327	deallocate the PCB. */
AdamGreen	0:616601bde9fb	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
AdamGreen	0:616601bde9fb	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
AdamGreen	0:616601bde9fb	330	memp_free(MEMP_TCP_PCB, pcb);
AdamGreen	0:616601bde9fb	331	} else if (recv_flags & TF_CLOSED) {
AdamGreen	0:616601bde9fb	332	/* The connection has been closed and we will deallocate the
AdamGreen	0:616601bde9fb	333	PCB. */
AdamGreen	0:616601bde9fb	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
AdamGreen	0:616601bde9fb	335	memp_free(MEMP_TCP_PCB, pcb);
AdamGreen	0:616601bde9fb	336	} else {
AdamGreen	0:616601bde9fb	337	err = ERR_OK;
AdamGreen	0:616601bde9fb	338	/* If the application has registered a "sent" function to be
AdamGreen	0:616601bde9fb	339	called when new send buffer space is available, we call it
AdamGreen	0:616601bde9fb	340	now. */
AdamGreen	0:616601bde9fb	341	if (pcb->acked > 0) {
AdamGreen	0:616601bde9fb	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
AdamGreen	0:616601bde9fb	343	if (err == ERR_ABRT) {
AdamGreen	0:616601bde9fb	344	goto aborted;
AdamGreen	0:616601bde9fb	345	}
AdamGreen	0:616601bde9fb	346	}
AdamGreen	0:616601bde9fb	347
AdamGreen	0:616601bde9fb	348	if (recv_data != NULL) {
AdamGreen	0:616601bde9fb	349	if (pcb->flags & TF_RXCLOSED) {
AdamGreen	0:616601bde9fb	350	/* received data although already closed -> abort (send RST) to
AdamGreen	0:616601bde9fb	351	notify the remote host that not all data has been processed */
AdamGreen	0:616601bde9fb	352	pbuf_free(recv_data);
AdamGreen	0:616601bde9fb	353	tcp_abort(pcb);
AdamGreen	0:616601bde9fb	354	goto aborted;
AdamGreen	0:616601bde9fb	355	}
AdamGreen	0:616601bde9fb	356	if (flags & TCP_PSH) {
AdamGreen	0:616601bde9fb	357	recv_data->flags \|= PBUF_FLAG_PUSH;
AdamGreen	0:616601bde9fb	358	}
AdamGreen	0:616601bde9fb	359
AdamGreen	0:616601bde9fb	360	/* Notify application that data has been received. */
AdamGreen	0:616601bde9fb	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
AdamGreen	0:616601bde9fb	362	if (err == ERR_ABRT) {
AdamGreen	0:616601bde9fb	363	goto aborted;
AdamGreen	0:616601bde9fb	364	}
AdamGreen	0:616601bde9fb	365
AdamGreen	0:616601bde9fb	366	/* If the upper layer can't receive this data, store it */
AdamGreen	0:616601bde9fb	367	if (err != ERR_OK) {
AdamGreen	0:616601bde9fb	368	pcb->refused_data = recv_data;
AdamGreen	0:616601bde9fb	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
AdamGreen	0:616601bde9fb	370	}
AdamGreen	0:616601bde9fb	371	}
AdamGreen	0:616601bde9fb	372
AdamGreen	0:616601bde9fb	373	/* If a FIN segment was received, we call the callback
AdamGreen	0:616601bde9fb	374	function with a NULL buffer to indicate EOF. */
AdamGreen	0:616601bde9fb	375	if (recv_flags & TF_GOT_FIN) {
AdamGreen	0:616601bde9fb	376	/* correct rcv_wnd as the application won't call tcp_recved()
AdamGreen	0:616601bde9fb	377	for the FIN's seqno */
AdamGreen	0:616601bde9fb	378	if (pcb->rcv_wnd != TCP_WND) {
AdamGreen	0:616601bde9fb	379	pcb->rcv_wnd++;
AdamGreen	0:616601bde9fb	380	}
AdamGreen	0:616601bde9fb	381	TCP_EVENT_CLOSED(pcb, err);
AdamGreen	0:616601bde9fb	382	if (err == ERR_ABRT) {
AdamGreen	0:616601bde9fb	383	goto aborted;
AdamGreen	0:616601bde9fb	384	}
AdamGreen	0:616601bde9fb	385	}
AdamGreen	0:616601bde9fb	386
AdamGreen	0:616601bde9fb	387	tcp_input_pcb = NULL;
AdamGreen	0:616601bde9fb	388	/* Try to send something out. */
AdamGreen	0:616601bde9fb	389	tcp_output(pcb);
AdamGreen	0:616601bde9fb	390	#if TCP_INPUT_DEBUG
AdamGreen	0:616601bde9fb	391	#if TCP_DEBUG
AdamGreen	0:616601bde9fb	392	tcp_debug_print_state(pcb->state);
AdamGreen	0:616601bde9fb	393	#endif /* TCP_DEBUG */
AdamGreen	0:616601bde9fb	394	#endif /* TCP_INPUT_DEBUG */
AdamGreen	0:616601bde9fb	395	}
AdamGreen	0:616601bde9fb	396	}
AdamGreen	0:616601bde9fb	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
AdamGreen	0:616601bde9fb	398	Below this line, 'pcb' may not be dereferenced! */
AdamGreen	0:616601bde9fb	399	aborted:
AdamGreen	0:616601bde9fb	400	tcp_input_pcb = NULL;
AdamGreen	0:616601bde9fb	401	recv_data = NULL;
AdamGreen	0:616601bde9fb	402
AdamGreen	0:616601bde9fb	403	/* give up our reference to inseg.p */
AdamGreen	0:616601bde9fb	404	if (inseg.p != NULL)
AdamGreen	0:616601bde9fb	405	{
AdamGreen	0:616601bde9fb	406	pbuf_free(inseg.p);
AdamGreen	0:616601bde9fb	407	inseg.p = NULL;
AdamGreen	0:616601bde9fb	408	}
AdamGreen	0:616601bde9fb	409	} else {
AdamGreen	0:616601bde9fb	410
AdamGreen	0:616601bde9fb	411	/* If no matching PCB was found, send a TCP RST (reset) to the
AdamGreen	0:616601bde9fb	412	sender. */
AdamGreen	0:616601bde9fb	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
AdamGreen	0:616601bde9fb	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
AdamGreen	0:616601bde9fb	415	TCP_STATS_INC(tcp.proterr);
AdamGreen	0:616601bde9fb	416	TCP_STATS_INC(tcp.drop);
AdamGreen	0:616601bde9fb	417	tcp_rst(ackno, seqno + tcplen,
AdamGreen	0:616601bde9fb	418	ip_current_dest_addr(), ip_current_src_addr(),
AdamGreen	0:616601bde9fb	419	tcphdr->dest, tcphdr->src);
AdamGreen	0:616601bde9fb	420	}
AdamGreen	0:616601bde9fb	421	pbuf_free(p);
AdamGreen	0:616601bde9fb	422	}
AdamGreen	0:616601bde9fb	423
AdamGreen	0:616601bde9fb	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
AdamGreen	0:616601bde9fb	425	PERF_STOP("tcp_input");
AdamGreen	0:616601bde9fb	426	}
AdamGreen	0:616601bde9fb	427
AdamGreen	0:616601bde9fb	428	/**
AdamGreen	0:616601bde9fb	429	* Called by tcp_input() when a segment arrives for a listening
AdamGreen	0:616601bde9fb	430	* connection (from tcp_input()).
AdamGreen	0:616601bde9fb	431	*
AdamGreen	0:616601bde9fb	432	* @param pcb the tcp_pcb_listen for which a segment arrived
AdamGreen	0:616601bde9fb	433	* @return ERR_OK if the segment was processed
AdamGreen	0:616601bde9fb	434	* another err_t on error
AdamGreen	0:616601bde9fb	435	*
AdamGreen	0:616601bde9fb	436	* @note the return value is not (yet?) used in tcp_input()
AdamGreen	0:616601bde9fb	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
AdamGreen	0:616601bde9fb	438	* involved is passed as a parameter to this function
AdamGreen	0:616601bde9fb	439	*/
AdamGreen	0:616601bde9fb	440	static err_t
AdamGreen	0:616601bde9fb	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
AdamGreen	0:616601bde9fb	442	{
AdamGreen	0:616601bde9fb	443	struct tcp_pcb *npcb;
AdamGreen	0:616601bde9fb	444	err_t rc;
AdamGreen	0:616601bde9fb	445
AdamGreen	0:616601bde9fb	446	/* In the LISTEN state, we check for incoming SYN segments,
AdamGreen	0:616601bde9fb	447	creates a new PCB, and responds with a SYN\|ACK. */
AdamGreen	0:616601bde9fb	448	if (flags & TCP_ACK) {
AdamGreen	0:616601bde9fb	449	/* For incoming segments with the ACK flag set, respond with a
AdamGreen	0:616601bde9fb	450	RST. */
AdamGreen	0:616601bde9fb	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
AdamGreen	0:616601bde9fb	452	tcp_rst(ackno + 1, seqno + tcplen,
AdamGreen	0:616601bde9fb	453	ip_current_dest_addr(), ip_current_src_addr(),
AdamGreen	0:616601bde9fb	454	tcphdr->dest, tcphdr->src);
AdamGreen	0:616601bde9fb	455	} else if (flags & TCP_SYN) {
AdamGreen	0:616601bde9fb	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
AdamGreen	0:616601bde9fb	457	#if TCP_LISTEN_BACKLOG
AdamGreen	0:616601bde9fb	458	if (pcb->accepts_pending >= pcb->backlog) {
AdamGreen	0:616601bde9fb	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
AdamGreen	0:616601bde9fb	460	return ERR_ABRT;
AdamGreen	0:616601bde9fb	461	}
AdamGreen	0:616601bde9fb	462	#endif /* TCP_LISTEN_BACKLOG */
AdamGreen	0:616601bde9fb	463	npcb = tcp_alloc(pcb->prio);
AdamGreen	0:616601bde9fb	464	/* If a new PCB could not be created (probably due to lack of memory),
AdamGreen	0:616601bde9fb	465	we don't do anything, but rely on the sender will retransmit the
AdamGreen	0:616601bde9fb	466	SYN at a time when we have more memory available. */
AdamGreen	0:616601bde9fb	467	if (npcb == NULL) {
AdamGreen	0:616601bde9fb	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
AdamGreen	0:616601bde9fb	469	TCP_STATS_INC(tcp.memerr);
AdamGreen	0:616601bde9fb	470	return ERR_MEM;
AdamGreen	0:616601bde9fb	471	}
AdamGreen	0:616601bde9fb	472	#if TCP_LISTEN_BACKLOG
AdamGreen	0:616601bde9fb	473	pcb->accepts_pending++;
AdamGreen	0:616601bde9fb	474	#endif /* TCP_LISTEN_BACKLOG */
AdamGreen	0:616601bde9fb	475	/* Set up the new PCB. */
AdamGreen	0:616601bde9fb	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
AdamGreen	0:616601bde9fb	477	npcb->local_port = pcb->local_port;
AdamGreen	0:616601bde9fb	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
AdamGreen	0:616601bde9fb	479	npcb->remote_port = tcphdr->src;
AdamGreen	0:616601bde9fb	480	npcb->state = SYN_RCVD;
AdamGreen	0:616601bde9fb	481	npcb->rcv_nxt = seqno + 1;
AdamGreen	0:616601bde9fb	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
AdamGreen	0:616601bde9fb	483	npcb->snd_wnd = tcphdr->wnd;
AdamGreen	0:616601bde9fb	484	npcb->ssthresh = npcb->snd_wnd;
AdamGreen	0:616601bde9fb	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
AdamGreen	0:616601bde9fb	486	npcb->callback_arg = pcb->callback_arg;
AdamGreen	0:616601bde9fb	487	#if LWIP_CALLBACK_API
AdamGreen	0:616601bde9fb	488	npcb->accept = pcb->accept;
AdamGreen	0:616601bde9fb	489	#endif /* LWIP_CALLBACK_API */
AdamGreen	0:616601bde9fb	490	/* inherit socket options */
AdamGreen	0:616601bde9fb	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
AdamGreen	0:616601bde9fb	492	/* Register the new PCB so that we can begin receiving segments
AdamGreen	0:616601bde9fb	493	for it. */
AdamGreen	0:616601bde9fb	494	TCP_REG(&tcp_active_pcbs, npcb);
AdamGreen	0:616601bde9fb	495
AdamGreen	0:616601bde9fb	496	/* Parse any options in the SYN. */
AdamGreen	0:616601bde9fb	497	tcp_parseopt(npcb);
AdamGreen	0:616601bde9fb	498	#if TCP_CALCULATE_EFF_SEND_MSS
AdamGreen	0:616601bde9fb	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
AdamGreen	0:616601bde9fb	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
AdamGreen	0:616601bde9fb	501
AdamGreen	0:616601bde9fb	502	snmp_inc_tcppassiveopens();
AdamGreen	0:616601bde9fb	503
AdamGreen	0:616601bde9fb	504	/* Send a SYN\|ACK together with the MSS option. */
AdamGreen	0:616601bde9fb	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
AdamGreen	0:616601bde9fb	506	if (rc != ERR_OK) {
AdamGreen	0:616601bde9fb	507	tcp_abandon(npcb, 0);
AdamGreen	0:616601bde9fb	508	return rc;
AdamGreen	0:616601bde9fb	509	}
AdamGreen	0:616601bde9fb	510	return tcp_output(npcb);
AdamGreen	0:616601bde9fb	511	}
AdamGreen	0:616601bde9fb	512	return ERR_OK;
AdamGreen	0:616601bde9fb	513	}
AdamGreen	0:616601bde9fb	514
AdamGreen	0:616601bde9fb	515	/**
AdamGreen	0:616601bde9fb	516	* Called by tcp_input() when a segment arrives for a connection in
AdamGreen	0:616601bde9fb	517	* TIME_WAIT.
AdamGreen	0:616601bde9fb	518	*
AdamGreen	0:616601bde9fb	519	* @param pcb the tcp_pcb for which a segment arrived
AdamGreen	0:616601bde9fb	520	*
AdamGreen	0:616601bde9fb	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
AdamGreen	0:616601bde9fb	522	* involved is passed as a parameter to this function
AdamGreen	0:616601bde9fb	523	*/
AdamGreen	0:616601bde9fb	524	static err_t
AdamGreen	0:616601bde9fb	525	tcp_timewait_input(struct tcp_pcb *pcb)
AdamGreen	0:616601bde9fb	526	{
AdamGreen	0:616601bde9fb	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
AdamGreen	0:616601bde9fb	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
AdamGreen	0:616601bde9fb	529	* - first check sequence number - we skip that one in TIME_WAIT (always
AdamGreen	0:616601bde9fb	530	* acceptable since we only send ACKs)
AdamGreen	0:616601bde9fb	531	* - second check the RST bit (... return) */
AdamGreen	0:616601bde9fb	532	if (flags & TCP_RST) {
AdamGreen	0:616601bde9fb	533	return ERR_OK;
AdamGreen	0:616601bde9fb	534	}
AdamGreen	0:616601bde9fb	535	/* - fourth, check the SYN bit, */
AdamGreen	0:616601bde9fb	536	if (flags & TCP_SYN) {
AdamGreen	0:616601bde9fb	537	/* If an incoming segment is not acceptable, an acknowledgment
AdamGreen	0:616601bde9fb	538	should be sent in reply */
AdamGreen	0:616601bde9fb	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
AdamGreen	0:616601bde9fb	540	/* If the SYN is in the window it is an error, send a reset */
AdamGreen	0:616601bde9fb	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
AdamGreen	0:616601bde9fb	542	tcphdr->dest, tcphdr->src);
AdamGreen	0:616601bde9fb	543	return ERR_OK;
AdamGreen	0:616601bde9fb	544	}
AdamGreen	0:616601bde9fb	545	} else if (flags & TCP_FIN) {
AdamGreen	0:616601bde9fb	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
AdamGreen	0:616601bde9fb	547	Restart the 2 MSL time-wait timeout.*/
AdamGreen	0:616601bde9fb	548	pcb->tmr = tcp_ticks;
AdamGreen	0:616601bde9fb	549	}
AdamGreen	0:616601bde9fb	550
AdamGreen	0:616601bde9fb	551	if ((tcplen > 0)) {
AdamGreen	0:616601bde9fb	552	/* Acknowledge data, FIN or out-of-window SYN */
AdamGreen	0:616601bde9fb	553	pcb->flags \|= TF_ACK_NOW;
AdamGreen	0:616601bde9fb	554	return tcp_output(pcb);
AdamGreen	0:616601bde9fb	555	}
AdamGreen	0:616601bde9fb	556	return ERR_OK;
AdamGreen	0:616601bde9fb	557	}
AdamGreen	0:616601bde9fb	558
AdamGreen	0:616601bde9fb	559	/**
AdamGreen	0:616601bde9fb	560	* Implements the TCP state machine. Called by tcp_input. In some
AdamGreen	0:616601bde9fb	561	* states tcp_receive() is called to receive data. The tcp_seg
AdamGreen	0:616601bde9fb	562	* argument will be freed by the caller (tcp_input()) unless the
AdamGreen	0:616601bde9fb	563	* recv_data pointer in the pcb is set.
AdamGreen	0:616601bde9fb	564	*
AdamGreen	0:616601bde9fb	565	* @param pcb the tcp_pcb for which a segment arrived
AdamGreen	0:616601bde9fb	566	*
AdamGreen	0:616601bde9fb	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
AdamGreen	0:616601bde9fb	568	* involved is passed as a parameter to this function
AdamGreen	0:616601bde9fb	569	*/
AdamGreen	0:616601bde9fb	570	static err_t
AdamGreen	0:616601bde9fb	571	tcp_process(struct tcp_pcb *pcb)
AdamGreen	0:616601bde9fb	572	{
AdamGreen	0:616601bde9fb	573	struct tcp_seg *rseg;
AdamGreen	0:616601bde9fb	574	u8_t acceptable = 0;
AdamGreen	0:616601bde9fb	575	err_t err;
AdamGreen	0:616601bde9fb	576
AdamGreen	0:616601bde9fb	577	err = ERR_OK;
AdamGreen	0:616601bde9fb	578
AdamGreen	0:616601bde9fb	579	/* Process incoming RST segments. */
AdamGreen	0:616601bde9fb	580	if (flags & TCP_RST) {
AdamGreen	0:616601bde9fb	581	/* First, determine if the reset is acceptable. */
AdamGreen	0:616601bde9fb	582	if (pcb->state == SYN_SENT) {
AdamGreen	0:616601bde9fb	583	if (ackno == pcb->snd_nxt) {
AdamGreen	0:616601bde9fb	584	acceptable = 1;
AdamGreen	0:616601bde9fb	585	}
AdamGreen	0:616601bde9fb	586	} else {
AdamGreen	0:616601bde9fb	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
AdamGreen	0:616601bde9fb	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
AdamGreen	0:616601bde9fb	589	acceptable = 1;
AdamGreen	0:616601bde9fb	590	}
AdamGreen	0:616601bde9fb	591	}
AdamGreen	0:616601bde9fb	592
AdamGreen	0:616601bde9fb	593	if (acceptable) {
AdamGreen	0:616601bde9fb	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
AdamGreen	0:616601bde9fb	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
AdamGreen	0:616601bde9fb	596	recv_flags \|= TF_RESET;
AdamGreen	0:616601bde9fb	597	pcb->flags &= ~TF_ACK_DELAY;
AdamGreen	0:616601bde9fb	598	return ERR_RST;
AdamGreen	0:616601bde9fb	599	} else {
AdamGreen	0:616601bde9fb	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
AdamGreen	0:616601bde9fb	601	seqno, pcb->rcv_nxt));
AdamGreen	0:616601bde9fb	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
AdamGreen	0:616601bde9fb	603	seqno, pcb->rcv_nxt));
AdamGreen	0:616601bde9fb	604	return ERR_OK;
AdamGreen	0:616601bde9fb	605	}
AdamGreen	0:616601bde9fb	606	}
AdamGreen	0:616601bde9fb	607
AdamGreen	0:616601bde9fb	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
AdamGreen	0:616601bde9fb	609	/* Cope with new connection attempt after remote end crashed */
AdamGreen	0:616601bde9fb	610	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	611	return ERR_OK;
AdamGreen	0:616601bde9fb	612	}
AdamGreen	0:616601bde9fb	613
AdamGreen	0:616601bde9fb	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
AdamGreen	0:616601bde9fb	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
AdamGreen	0:616601bde9fb	616	pcb->tmr = tcp_ticks;
AdamGreen	0:616601bde9fb	617	}
AdamGreen	0:616601bde9fb	618	pcb->keep_cnt_sent = 0;
AdamGreen	0:616601bde9fb	619
AdamGreen	0:616601bde9fb	620	tcp_parseopt(pcb);
AdamGreen	0:616601bde9fb	621
AdamGreen	0:616601bde9fb	622	/* Do different things depending on the TCP state. */
AdamGreen	0:616601bde9fb	623	switch (pcb->state) {
AdamGreen	0:616601bde9fb	624	case SYN_SENT:
AdamGreen	0:616601bde9fb	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
AdamGreen	0:616601bde9fb	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
AdamGreen	0:616601bde9fb	627	/* received SYN ACK with expected sequence number? */
AdamGreen	0:616601bde9fb	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
AdamGreen	0:616601bde9fb	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
AdamGreen	0:616601bde9fb	630	pcb->snd_buf++;
AdamGreen	0:616601bde9fb	631	pcb->rcv_nxt = seqno + 1;
AdamGreen	0:616601bde9fb	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
AdamGreen	0:616601bde9fb	633	pcb->lastack = ackno;
AdamGreen	0:616601bde9fb	634	pcb->snd_wnd = tcphdr->wnd;
AdamGreen	0:616601bde9fb	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
AdamGreen	0:616601bde9fb	636	pcb->state = ESTABLISHED;
AdamGreen	0:616601bde9fb	637
AdamGreen	0:616601bde9fb	638	#if TCP_CALCULATE_EFF_SEND_MSS
AdamGreen	0:616601bde9fb	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
AdamGreen	0:616601bde9fb	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
AdamGreen	0:616601bde9fb	641
AdamGreen	0:616601bde9fb	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
AdamGreen	0:616601bde9fb	643	* but for the default value of pcb->mss) */
AdamGreen	0:616601bde9fb	644	pcb->ssthresh = pcb->mss * 10;
AdamGreen	0:616601bde9fb	645
AdamGreen	0:616601bde9fb	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
AdamGreen	0:616601bde9fb	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
AdamGreen	0:616601bde9fb	648	--pcb->snd_queuelen;
AdamGreen	0:616601bde9fb	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
AdamGreen	0:616601bde9fb	650	rseg = pcb->unacked;
AdamGreen	0:616601bde9fb	651	pcb->unacked = rseg->next;
AdamGreen	0:616601bde9fb	652
AdamGreen	0:616601bde9fb	653	/* If there's nothing left to acknowledge, stop the retransmit
AdamGreen	0:616601bde9fb	654	timer, otherwise reset it to start again */
AdamGreen	0:616601bde9fb	655	if(pcb->unacked == NULL)
AdamGreen	0:616601bde9fb	656	pcb->rtime = -1;
AdamGreen	0:616601bde9fb	657	else {
AdamGreen	0:616601bde9fb	658	pcb->rtime = 0;
AdamGreen	0:616601bde9fb	659	pcb->nrtx = 0;
AdamGreen	0:616601bde9fb	660	}
AdamGreen	0:616601bde9fb	661
AdamGreen	0:616601bde9fb	662	tcp_seg_free(rseg);
AdamGreen	0:616601bde9fb	663
AdamGreen	0:616601bde9fb	664	/* Call the user specified function to call when sucessfully
AdamGreen	0:616601bde9fb	665	* connected. */
AdamGreen	0:616601bde9fb	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
AdamGreen	0:616601bde9fb	667	if (err == ERR_ABRT) {
AdamGreen	0:616601bde9fb	668	return ERR_ABRT;
AdamGreen	0:616601bde9fb	669	}
AdamGreen	0:616601bde9fb	670	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	671	}
AdamGreen	0:616601bde9fb	672	/* received ACK? possibly a half-open connection */
AdamGreen	0:616601bde9fb	673	else if (flags & TCP_ACK) {
AdamGreen	0:616601bde9fb	674	/* send a RST to bring the other side in a non-synchronized state. */
AdamGreen	0:616601bde9fb	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
AdamGreen	0:616601bde9fb	676	tcphdr->dest, tcphdr->src);
AdamGreen	0:616601bde9fb	677	}
AdamGreen	0:616601bde9fb	678	break;
AdamGreen	0:616601bde9fb	679	case SYN_RCVD:
AdamGreen	0:616601bde9fb	680	if (flags & TCP_ACK) {
AdamGreen	0:616601bde9fb	681	/* expected ACK number? */
AdamGreen	0:616601bde9fb	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
AdamGreen	0:616601bde9fb	683	u16_t old_cwnd;
AdamGreen	0:616601bde9fb	684	pcb->state = ESTABLISHED;
AdamGreen	0:616601bde9fb	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
AdamGreen	0:616601bde9fb	686	#if LWIP_CALLBACK_API
AdamGreen	0:616601bde9fb	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
AdamGreen	0:616601bde9fb	688	#endif
AdamGreen	0:616601bde9fb	689	/* Call the accept function. */
AdamGreen	0:616601bde9fb	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
AdamGreen	0:616601bde9fb	691	if (err != ERR_OK) {
AdamGreen	0:616601bde9fb	692	/* If the accept function returns with an error, we abort
AdamGreen	0:616601bde9fb	693	* the connection. */
AdamGreen	0:616601bde9fb	694	/* Already aborted? */
AdamGreen	0:616601bde9fb	695	if (err != ERR_ABRT) {
AdamGreen	0:616601bde9fb	696	tcp_abort(pcb);
AdamGreen	0:616601bde9fb	697	}
AdamGreen	0:616601bde9fb	698	return ERR_ABRT;
AdamGreen	0:616601bde9fb	699	}
AdamGreen	0:616601bde9fb	700	old_cwnd = pcb->cwnd;
AdamGreen	0:616601bde9fb	701	/* If there was any data contained within this ACK,
AdamGreen	0:616601bde9fb	702	* we'd better pass it on to the application as well. */
AdamGreen	0:616601bde9fb	703	tcp_receive(pcb);
AdamGreen	0:616601bde9fb	704
AdamGreen	0:616601bde9fb	705	/* Prevent ACK for SYN to generate a sent event */
AdamGreen	0:616601bde9fb	706	if (pcb->acked != 0) {
AdamGreen	0:616601bde9fb	707	pcb->acked--;
AdamGreen	0:616601bde9fb	708	}
AdamGreen	0:616601bde9fb	709
AdamGreen	0:616601bde9fb	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
AdamGreen	0:616601bde9fb	711
AdamGreen	0:616601bde9fb	712	if (recv_flags & TF_GOT_FIN) {
AdamGreen	0:616601bde9fb	713	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	714	pcb->state = CLOSE_WAIT;
AdamGreen	0:616601bde9fb	715	}
AdamGreen	0:616601bde9fb	716	} else {
AdamGreen	0:616601bde9fb	717	/* incorrect ACK number, send RST */
AdamGreen	0:616601bde9fb	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
AdamGreen	0:616601bde9fb	719	tcphdr->dest, tcphdr->src);
AdamGreen	0:616601bde9fb	720	}
AdamGreen	0:616601bde9fb	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
AdamGreen	0:616601bde9fb	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
AdamGreen	0:616601bde9fb	723	tcp_rexmit(pcb);
AdamGreen	0:616601bde9fb	724	}
AdamGreen	0:616601bde9fb	725	break;
AdamGreen	0:616601bde9fb	726	case CLOSE_WAIT:
AdamGreen	0:616601bde9fb	727	/* FALLTHROUGH */
AdamGreen	0:616601bde9fb	728	case ESTABLISHED:
AdamGreen	0:616601bde9fb	729	tcp_receive(pcb);
AdamGreen	0:616601bde9fb	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
AdamGreen	0:616601bde9fb	731	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	732	pcb->state = CLOSE_WAIT;
AdamGreen	0:616601bde9fb	733	}
AdamGreen	0:616601bde9fb	734	break;
AdamGreen	0:616601bde9fb	735	case FIN_WAIT_1:
AdamGreen	0:616601bde9fb	736	tcp_receive(pcb);
AdamGreen	0:616601bde9fb	737	if (recv_flags & TF_GOT_FIN) {
AdamGreen	0:616601bde9fb	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
AdamGreen	0:616601bde9fb	739	LWIP_DEBUGF(TCP_DEBUG,
AdamGreen	0:616601bde9fb	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
AdamGreen	0:616601bde9fb	741	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	742	tcp_pcb_purge(pcb);
AdamGreen	0:616601bde9fb	743	TCP_RMV(&tcp_active_pcbs, pcb);
AdamGreen	0:616601bde9fb	744	pcb->state = TIME_WAIT;
AdamGreen	0:616601bde9fb	745	TCP_REG(&tcp_tw_pcbs, pcb);
AdamGreen	0:616601bde9fb	746	} else {
AdamGreen	0:616601bde9fb	747	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	748	pcb->state = CLOSING;
AdamGreen	0:616601bde9fb	749	}
AdamGreen	0:616601bde9fb	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
AdamGreen	0:616601bde9fb	751	pcb->state = FIN_WAIT_2;
AdamGreen	0:616601bde9fb	752	}
AdamGreen	0:616601bde9fb	753	break;
AdamGreen	0:616601bde9fb	754	case FIN_WAIT_2:
AdamGreen	0:616601bde9fb	755	tcp_receive(pcb);
AdamGreen	0:616601bde9fb	756	if (recv_flags & TF_GOT_FIN) {
AdamGreen	0:616601bde9fb	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
AdamGreen	0:616601bde9fb	758	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	759	tcp_pcb_purge(pcb);
AdamGreen	0:616601bde9fb	760	TCP_RMV(&tcp_active_pcbs, pcb);
AdamGreen	0:616601bde9fb	761	pcb->state = TIME_WAIT;
AdamGreen	0:616601bde9fb	762	TCP_REG(&tcp_tw_pcbs, pcb);
AdamGreen	0:616601bde9fb	763	}
AdamGreen	0:616601bde9fb	764	break;
AdamGreen	0:616601bde9fb	765	case CLOSING:
AdamGreen	0:616601bde9fb	766	tcp_receive(pcb);
AdamGreen	0:616601bde9fb	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
AdamGreen	0:616601bde9fb	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
AdamGreen	0:616601bde9fb	769	tcp_pcb_purge(pcb);
AdamGreen	0:616601bde9fb	770	TCP_RMV(&tcp_active_pcbs, pcb);
AdamGreen	0:616601bde9fb	771	pcb->state = TIME_WAIT;
AdamGreen	0:616601bde9fb	772	TCP_REG(&tcp_tw_pcbs, pcb);
AdamGreen	0:616601bde9fb	773	}
AdamGreen	0:616601bde9fb	774	break;
AdamGreen	0:616601bde9fb	775	case LAST_ACK:
AdamGreen	0:616601bde9fb	776	tcp_receive(pcb);
AdamGreen	0:616601bde9fb	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
AdamGreen	0:616601bde9fb	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
AdamGreen	0:616601bde9fb	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
AdamGreen	0:616601bde9fb	780	recv_flags \|= TF_CLOSED;
AdamGreen	0:616601bde9fb	781	}
AdamGreen	0:616601bde9fb	782	break;
AdamGreen	0:616601bde9fb	783	default:
AdamGreen	0:616601bde9fb	784	break;
AdamGreen	0:616601bde9fb	785	}
AdamGreen	0:616601bde9fb	786	return ERR_OK;
AdamGreen	0:616601bde9fb	787	}
AdamGreen	0:616601bde9fb	788
AdamGreen	0:616601bde9fb	789	#if TCP_QUEUE_OOSEQ
AdamGreen	0:616601bde9fb	790	/**
AdamGreen	0:616601bde9fb	791	* Insert segment into the list (segments covered with new one will be deleted)
AdamGreen	0:616601bde9fb	792	*
AdamGreen	0:616601bde9fb	793	* Called from tcp_receive()
AdamGreen	0:616601bde9fb	794	*/
AdamGreen	0:616601bde9fb	795	static void
AdamGreen	0:616601bde9fb	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
AdamGreen	0:616601bde9fb	797	{
AdamGreen	0:616601bde9fb	798	struct tcp_seg *old_seg;
AdamGreen	0:616601bde9fb	799
AdamGreen	0:616601bde9fb	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	801	/* received segment overlaps all following segments */
AdamGreen	0:616601bde9fb	802	tcp_segs_free(next);
AdamGreen	0:616601bde9fb	803	next = NULL;
AdamGreen	0:616601bde9fb	804	}
AdamGreen	0:616601bde9fb	805	else {
AdamGreen	0:616601bde9fb	806	/* delete some following segments
AdamGreen	0:616601bde9fb	807	oos queue may have segments with FIN flag */
AdamGreen	0:616601bde9fb	808	while (next &&
AdamGreen	0:616601bde9fb	809	TCP_SEQ_GEQ((seqno + cseg->len),
AdamGreen	0:616601bde9fb	810	(next->tcphdr->seqno + next->len))) {
AdamGreen	0:616601bde9fb	811	/* cseg with FIN already processed */
AdamGreen	0:616601bde9fb	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
AdamGreen	0:616601bde9fb	814	}
AdamGreen	0:616601bde9fb	815	old_seg = next;
AdamGreen	0:616601bde9fb	816	next = next->next;
AdamGreen	0:616601bde9fb	817	tcp_seg_free(old_seg);
AdamGreen	0:616601bde9fb	818	}
AdamGreen	0:616601bde9fb	819	if (next &&
AdamGreen	0:616601bde9fb	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
AdamGreen	0:616601bde9fb	821	/* We need to trim the incoming segment. */
AdamGreen	0:616601bde9fb	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
AdamGreen	0:616601bde9fb	823	pbuf_realloc(cseg->p, cseg->len);
AdamGreen	0:616601bde9fb	824	}
AdamGreen	0:616601bde9fb	825	}
AdamGreen	0:616601bde9fb	826	cseg->next = next;
AdamGreen	0:616601bde9fb	827	}
AdamGreen	0:616601bde9fb	828	#endif /* TCP_QUEUE_OOSEQ */
AdamGreen	0:616601bde9fb	829
AdamGreen	0:616601bde9fb	830	/**
AdamGreen	0:616601bde9fb	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
AdamGreen	0:616601bde9fb	832	* data, and if so frees the memory of the buffered data. Next, is places the
AdamGreen	0:616601bde9fb	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
AdamGreen	0:616601bde9fb	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
AdamGreen	0:616601bde9fb	835	* i it has been removed from the buffer.
AdamGreen	0:616601bde9fb	836	*
AdamGreen	0:616601bde9fb	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
AdamGreen	0:616601bde9fb	838	* estimation, the RTT is estimated here as well.
AdamGreen	0:616601bde9fb	839	*
AdamGreen	0:616601bde9fb	840	* Called from tcp_process().
AdamGreen	0:616601bde9fb	841	*/
AdamGreen	0:616601bde9fb	842	static void
AdamGreen	0:616601bde9fb	843	tcp_receive(struct tcp_pcb *pcb)
AdamGreen	0:616601bde9fb	844	{
AdamGreen	0:616601bde9fb	845	struct tcp_seg *next;
AdamGreen	0:616601bde9fb	846	#if TCP_QUEUE_OOSEQ
AdamGreen	0:616601bde9fb	847	struct tcp_seg prev, cseg;
AdamGreen	0:616601bde9fb	848	#endif /* TCP_QUEUE_OOSEQ */
AdamGreen	0:616601bde9fb	849	struct pbuf *p;
AdamGreen	0:616601bde9fb	850	s32_t off;
AdamGreen	0:616601bde9fb	851	s16_t m;
AdamGreen	0:616601bde9fb	852	u32_t right_wnd_edge;
AdamGreen	0:616601bde9fb	853	u16_t new_tot_len;
AdamGreen	0:616601bde9fb	854	int found_dupack = 0;
AdamGreen	0:616601bde9fb	855
AdamGreen	0:616601bde9fb	856	if (flags & TCP_ACK) {
AdamGreen	0:616601bde9fb	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
AdamGreen	0:616601bde9fb	858
AdamGreen	0:616601bde9fb	859	/* Update window. */
AdamGreen	0:616601bde9fb	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
AdamGreen	0:616601bde9fb	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
AdamGreen	0:616601bde9fb	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
AdamGreen	0:616601bde9fb	863	pcb->snd_wnd = tcphdr->wnd;
AdamGreen	0:616601bde9fb	864	pcb->snd_wl1 = seqno;
AdamGreen	0:616601bde9fb	865	pcb->snd_wl2 = ackno;
AdamGreen	0:616601bde9fb	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
AdamGreen	0:616601bde9fb	867	pcb->persist_backoff = 0;
AdamGreen	0:616601bde9fb	868	}
AdamGreen	0:616601bde9fb	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
AdamGreen	0:616601bde9fb	870	#if TCP_WND_DEBUG
AdamGreen	0:616601bde9fb	871	} else {
AdamGreen	0:616601bde9fb	872	if (pcb->snd_wnd != tcphdr->wnd) {
AdamGreen	0:616601bde9fb	873	LWIP_DEBUGF(TCP_WND_DEBUG,
AdamGreen	0:616601bde9fb	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
AdamGreen	0:616601bde9fb	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
AdamGreen	0:616601bde9fb	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
AdamGreen	0:616601bde9fb	877	}
AdamGreen	0:616601bde9fb	878	#endif /* TCP_WND_DEBUG */
AdamGreen	0:616601bde9fb	879	}
AdamGreen	0:616601bde9fb	880
AdamGreen	0:616601bde9fb	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
AdamGreen	0:616601bde9fb	882	* duplicate ack if:
AdamGreen	0:616601bde9fb	883	* 1) It doesn't ACK new data
AdamGreen	0:616601bde9fb	884	* 2) length of received packet is zero (i.e. no payload)
AdamGreen	0:616601bde9fb	885	* 3) the advertised window hasn't changed
AdamGreen	0:616601bde9fb	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
AdamGreen	0:616601bde9fb	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
AdamGreen	0:616601bde9fb	888	*
AdamGreen	0:616601bde9fb	889	* If it passes all five, should process as a dupack:
AdamGreen	0:616601bde9fb	890	* a) dupacks < 3: do nothing
AdamGreen	0:616601bde9fb	891	* b) dupacks == 3: fast retransmit
AdamGreen	0:616601bde9fb	892	* c) dupacks > 3: increase cwnd
AdamGreen	0:616601bde9fb	893	*
AdamGreen	0:616601bde9fb	894	* If it only passes 1-3, should reset dupack counter (and add to
AdamGreen	0:616601bde9fb	895	* stats, which we don't do in lwIP)
AdamGreen	0:616601bde9fb	896	*
AdamGreen	0:616601bde9fb	897	* If it only passes 1, should reset dupack counter
AdamGreen	0:616601bde9fb	898	*
AdamGreen	0:616601bde9fb	899	*/
AdamGreen	0:616601bde9fb	900
AdamGreen	0:616601bde9fb	901	/* Clause 1 */
AdamGreen	0:616601bde9fb	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
AdamGreen	0:616601bde9fb	903	pcb->acked = 0;
AdamGreen	0:616601bde9fb	904	/* Clause 2 */
AdamGreen	0:616601bde9fb	905	if (tcplen == 0) {
AdamGreen	0:616601bde9fb	906	/* Clause 3 */
AdamGreen	0:616601bde9fb	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
AdamGreen	0:616601bde9fb	908	/* Clause 4 */
AdamGreen	0:616601bde9fb	909	if (pcb->rtime >= 0) {
AdamGreen	0:616601bde9fb	910	/* Clause 5 */
AdamGreen	0:616601bde9fb	911	if (pcb->lastack == ackno) {
AdamGreen	0:616601bde9fb	912	found_dupack = 1;
AdamGreen	0:616601bde9fb	913	if (pcb->dupacks + 1 > pcb->dupacks)
AdamGreen	0:616601bde9fb	914	++pcb->dupacks;
AdamGreen	0:616601bde9fb	915	if (pcb->dupacks > 3) {
AdamGreen	0:616601bde9fb	916	/* Inflate the congestion window, but not if it means that
AdamGreen	0:616601bde9fb	917	the value overflows. */
AdamGreen	0:616601bde9fb	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
AdamGreen	0:616601bde9fb	919	pcb->cwnd += pcb->mss;
AdamGreen	0:616601bde9fb	920	}
AdamGreen	0:616601bde9fb	921	} else if (pcb->dupacks == 3) {
AdamGreen	0:616601bde9fb	922	/* Do fast retransmit */
AdamGreen	0:616601bde9fb	923	tcp_rexmit_fast(pcb);
AdamGreen	0:616601bde9fb	924	}
AdamGreen	0:616601bde9fb	925	}
AdamGreen	0:616601bde9fb	926	}
AdamGreen	0:616601bde9fb	927	}
AdamGreen	0:616601bde9fb	928	}
AdamGreen	0:616601bde9fb	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
AdamGreen	0:616601bde9fb	930	* count of consecutive duplicate acks */
AdamGreen	0:616601bde9fb	931	if (!found_dupack) {
AdamGreen	0:616601bde9fb	932	pcb->dupacks = 0;
AdamGreen	0:616601bde9fb	933	}
AdamGreen	0:616601bde9fb	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
AdamGreen	0:616601bde9fb	935	/* We come here when the ACK acknowledges new data. */
AdamGreen	0:616601bde9fb	936
AdamGreen	0:616601bde9fb	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
AdamGreen	0:616601bde9fb	938	in fast retransmit. Also reset the congestion window to the
AdamGreen	0:616601bde9fb	939	slow start threshold. */
AdamGreen	0:616601bde9fb	940	if (pcb->flags & TF_INFR) {
AdamGreen	0:616601bde9fb	941	pcb->flags &= ~TF_INFR;
AdamGreen	0:616601bde9fb	942	pcb->cwnd = pcb->ssthresh;
AdamGreen	0:616601bde9fb	943	}
AdamGreen	0:616601bde9fb	944
AdamGreen	0:616601bde9fb	945	/* Reset the number of retransmissions. */
AdamGreen	0:616601bde9fb	946	pcb->nrtx = 0;
AdamGreen	0:616601bde9fb	947
AdamGreen	0:616601bde9fb	948	/* Reset the retransmission time-out. */
AdamGreen	0:616601bde9fb	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
AdamGreen	0:616601bde9fb	950
AdamGreen	0:616601bde9fb	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
AdamGreen	0:616601bde9fb	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
AdamGreen	0:616601bde9fb	953
AdamGreen	0:616601bde9fb	954	pcb->snd_buf += pcb->acked;
AdamGreen	0:616601bde9fb	955
AdamGreen	0:616601bde9fb	956	/* Reset the fast retransmit variables. */
AdamGreen	0:616601bde9fb	957	pcb->dupacks = 0;
AdamGreen	0:616601bde9fb	958	pcb->lastack = ackno;
AdamGreen	0:616601bde9fb	959
AdamGreen	0:616601bde9fb	960	/* Update the congestion control variables (cwnd and
AdamGreen	0:616601bde9fb	961	ssthresh). */
AdamGreen	0:616601bde9fb	962	if (pcb->state >= ESTABLISHED) {
AdamGreen	0:616601bde9fb	963	if (pcb->cwnd < pcb->ssthresh) {
AdamGreen	0:616601bde9fb	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
AdamGreen	0:616601bde9fb	965	pcb->cwnd += pcb->mss;
AdamGreen	0:616601bde9fb	966	}
AdamGreen	0:616601bde9fb	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
AdamGreen	0:616601bde9fb	968	} else {
AdamGreen	0:616601bde9fb	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
AdamGreen	0:616601bde9fb	970	if (new_cwnd > pcb->cwnd) {
AdamGreen	0:616601bde9fb	971	pcb->cwnd = new_cwnd;
AdamGreen	0:616601bde9fb	972	}
AdamGreen	0:616601bde9fb	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
AdamGreen	0:616601bde9fb	974	}
AdamGreen	0:616601bde9fb	975	}
AdamGreen	0:616601bde9fb	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
AdamGreen	0:616601bde9fb	977	ackno,
AdamGreen	0:616601bde9fb	978	pcb->unacked != NULL?
AdamGreen	0:616601bde9fb	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
AdamGreen	0:616601bde9fb	980	pcb->unacked != NULL?
AdamGreen	0:616601bde9fb	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
AdamGreen	0:616601bde9fb	982
AdamGreen	0:616601bde9fb	983	/* Remove segment from the unacknowledged list if the incoming
AdamGreen	0:616601bde9fb	984	ACK acknowlegdes them. */
AdamGreen	0:616601bde9fb	985	while (pcb->unacked != NULL &&
AdamGreen	0:616601bde9fb	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
AdamGreen	0:616601bde9fb	987	TCP_TCPLEN(pcb->unacked), ackno)) {
AdamGreen	0:616601bde9fb	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
AdamGreen	0:616601bde9fb	989	ntohl(pcb->unacked->tcphdr->seqno),
AdamGreen	0:616601bde9fb	990	ntohl(pcb->unacked->tcphdr->seqno) +
AdamGreen	0:616601bde9fb	991	TCP_TCPLEN(pcb->unacked)));
AdamGreen	0:616601bde9fb	992
AdamGreen	0:616601bde9fb	993	next = pcb->unacked;
AdamGreen	0:616601bde9fb	994	pcb->unacked = pcb->unacked->next;
AdamGreen	0:616601bde9fb	995
AdamGreen	0:616601bde9fb	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
AdamGreen	0:616601bde9fb	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
AdamGreen	0:616601bde9fb	998	/* Prevent ACK for FIN to generate a sent event */
AdamGreen	0:616601bde9fb	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
AdamGreen	0:616601bde9fb	1000	pcb->acked--;
AdamGreen	0:616601bde9fb	1001	}
AdamGreen	0:616601bde9fb	1002
AdamGreen	0:616601bde9fb	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
AdamGreen	0:616601bde9fb	1004	tcp_seg_free(next);
AdamGreen	0:616601bde9fb	1005
AdamGreen	0:616601bde9fb	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
AdamGreen	0:616601bde9fb	1007	if (pcb->snd_queuelen != 0) {
AdamGreen	0:616601bde9fb	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
AdamGreen	0:616601bde9fb	1009	pcb->unsent != NULL);
AdamGreen	0:616601bde9fb	1010	}
AdamGreen	0:616601bde9fb	1011	}
AdamGreen	0:616601bde9fb	1012
AdamGreen	0:616601bde9fb	1013	/* If there's nothing left to acknowledge, stop the retransmit
AdamGreen	0:616601bde9fb	1014	timer, otherwise reset it to start again */
AdamGreen	0:616601bde9fb	1015	if(pcb->unacked == NULL)
AdamGreen	0:616601bde9fb	1016	pcb->rtime = -1;
AdamGreen	0:616601bde9fb	1017	else
AdamGreen	0:616601bde9fb	1018	pcb->rtime = 0;
AdamGreen	0:616601bde9fb	1019
AdamGreen	0:616601bde9fb	1020	pcb->polltmr = 0;
AdamGreen	0:616601bde9fb	1021	} else {
AdamGreen	0:616601bde9fb	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
AdamGreen	0:616601bde9fb	1023	pcb->acked = 0;
AdamGreen	0:616601bde9fb	1024	}
AdamGreen	0:616601bde9fb	1025
AdamGreen	0:616601bde9fb	1026	/* We go through the ->unsent list to see if any of the segments
AdamGreen	0:616601bde9fb	1027	on the list are acknowledged by the ACK. This may seem
AdamGreen	0:616601bde9fb	1028	strange since an "unsent" segment shouldn't be acked. The
AdamGreen	0:616601bde9fb	1029	rationale is that lwIP puts all outstanding segments on the
AdamGreen	0:616601bde9fb	1030	->unsent list after a retransmission, so these segments may
AdamGreen	0:616601bde9fb	1031	in fact have been sent once. */
AdamGreen	0:616601bde9fb	1032	while (pcb->unsent != NULL &&
AdamGreen	0:616601bde9fb	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
AdamGreen	0:616601bde9fb	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
AdamGreen	0:616601bde9fb	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
AdamGreen	0:616601bde9fb	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
AdamGreen	0:616601bde9fb	1037	TCP_TCPLEN(pcb->unsent)));
AdamGreen	0:616601bde9fb	1038
AdamGreen	0:616601bde9fb	1039	next = pcb->unsent;
AdamGreen	0:616601bde9fb	1040	pcb->unsent = pcb->unsent->next;
AdamGreen	0:616601bde9fb	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
AdamGreen	0:616601bde9fb	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
AdamGreen	0:616601bde9fb	1043	/* Prevent ACK for FIN to generate a sent event */
AdamGreen	0:616601bde9fb	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
AdamGreen	0:616601bde9fb	1045	pcb->acked--;
AdamGreen	0:616601bde9fb	1046	}
AdamGreen	0:616601bde9fb	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
AdamGreen	0:616601bde9fb	1048	tcp_seg_free(next);
AdamGreen	0:616601bde9fb	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
AdamGreen	0:616601bde9fb	1050	if (pcb->snd_queuelen != 0) {
AdamGreen	0:616601bde9fb	1051	LWIP_ASSERT("tcp_receive: valid queue length",
AdamGreen	0:616601bde9fb	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
AdamGreen	0:616601bde9fb	1053	}
AdamGreen	0:616601bde9fb	1054	}
AdamGreen	0:616601bde9fb	1055	/* End of ACK for new data processing. */
AdamGreen	0:616601bde9fb	1056
AdamGreen	0:616601bde9fb	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
AdamGreen	0:616601bde9fb	1058	pcb->rttest, pcb->rtseq, ackno));
AdamGreen	0:616601bde9fb	1059
AdamGreen	0:616601bde9fb	1060	/* RTT estimation calculations. This is done by checking if the
AdamGreen	0:616601bde9fb	1061	incoming segment acknowledges the segment we use to take a
AdamGreen	0:616601bde9fb	1062	round-trip time measurement. */
AdamGreen	0:616601bde9fb	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
AdamGreen	0:616601bde9fb	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
AdamGreen	0:616601bde9fb	1065	and a round-trip shouldn't be that long... */
AdamGreen	0:616601bde9fb	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
AdamGreen	0:616601bde9fb	1067
AdamGreen	0:616601bde9fb	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
AdamGreen	0:616601bde9fb	1069	m, m * TCP_SLOW_INTERVAL));
AdamGreen	0:616601bde9fb	1070
AdamGreen	0:616601bde9fb	1071	/* This is taken directly from VJs original code in his paper */
AdamGreen	0:616601bde9fb	1072	m = m - (pcb->sa >> 3);
AdamGreen	0:616601bde9fb	1073	pcb->sa += m;
AdamGreen	0:616601bde9fb	1074	if (m < 0) {
AdamGreen	0:616601bde9fb	1075	m = -m;
AdamGreen	0:616601bde9fb	1076	}
AdamGreen	0:616601bde9fb	1077	m = m - (pcb->sv >> 2);
AdamGreen	0:616601bde9fb	1078	pcb->sv += m;
AdamGreen	0:616601bde9fb	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
AdamGreen	0:616601bde9fb	1080
AdamGreen	0:616601bde9fb	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
AdamGreen	0:616601bde9fb	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
AdamGreen	0:616601bde9fb	1083
AdamGreen	0:616601bde9fb	1084	pcb->rttest = 0;
AdamGreen	0:616601bde9fb	1085	}
AdamGreen	0:616601bde9fb	1086	}
AdamGreen	0:616601bde9fb	1087
AdamGreen	0:616601bde9fb	1088	/* If the incoming segment contains data, we must process it
AdamGreen	0:616601bde9fb	1089	further. */
AdamGreen	0:616601bde9fb	1090	if (tcplen > 0) {
AdamGreen	0:616601bde9fb	1091	/* This code basically does three things:
AdamGreen	0:616601bde9fb	1092
AdamGreen	0:616601bde9fb	1093	+) If the incoming segment contains data that is the next
AdamGreen	0:616601bde9fb	1094	in-sequence data, this data is passed to the application. This
AdamGreen	0:616601bde9fb	1095	might involve trimming the first edge of the data. The rcv_nxt
AdamGreen	0:616601bde9fb	1096	variable and the advertised window are adjusted.
AdamGreen	0:616601bde9fb	1097
AdamGreen	0:616601bde9fb	1098	+) If the incoming segment has data that is above the next
AdamGreen	0:616601bde9fb	1099	sequence number expected (->rcv_nxt), the segment is placed on
AdamGreen	0:616601bde9fb	1100	the ->ooseq queue. This is done by finding the appropriate
AdamGreen	0:616601bde9fb	1101	place in the ->ooseq queue (which is ordered by sequence
AdamGreen	0:616601bde9fb	1102	number) and trim the segment in both ends if needed. An
AdamGreen	0:616601bde9fb	1103	immediate ACK is sent to indicate that we received an
AdamGreen	0:616601bde9fb	1104	out-of-sequence segment.
AdamGreen	0:616601bde9fb	1105
AdamGreen	0:616601bde9fb	1106	+) Finally, we check if the first segment on the ->ooseq queue
AdamGreen	0:616601bde9fb	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
AdamGreen	0:616601bde9fb	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
AdamGreen	0:616601bde9fb	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
AdamGreen	0:616601bde9fb	1110	segments that are now on sequence are chained onto the
AdamGreen	0:616601bde9fb	1111	incoming segment so that we only need to call the application
AdamGreen	0:616601bde9fb	1112	once.
AdamGreen	0:616601bde9fb	1113	*/
AdamGreen	0:616601bde9fb	1114
AdamGreen	0:616601bde9fb	1115	/* First, we check if we must trim the first edge. We have to do
AdamGreen	0:616601bde9fb	1116	this if the sequence number of the incoming segment is less
AdamGreen	0:616601bde9fb	1117	than rcv_nxt, and the sequence number plus the length of the
AdamGreen	0:616601bde9fb	1118	segment is larger than rcv_nxt. */
AdamGreen	0:616601bde9fb	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
AdamGreen	0:616601bde9fb	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
AdamGreen	0:616601bde9fb	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
AdamGreen	0:616601bde9fb	1122	/* Trimming the first edge is done by pushing the payload
AdamGreen	0:616601bde9fb	1123	pointer in the pbuf downwards. This is somewhat tricky since
AdamGreen	0:616601bde9fb	1124	we do not want to discard the full contents of the pbuf up to
AdamGreen	0:616601bde9fb	1125	the new starting point of the data since we have to keep the
AdamGreen	0:616601bde9fb	1126	TCP header which is present in the first pbuf in the chain.
AdamGreen	0:616601bde9fb	1127
AdamGreen	0:616601bde9fb	1128	What is done is really quite a nasty hack: the first pbuf in
AdamGreen	0:616601bde9fb	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
AdamGreen	0:616601bde9fb	1130	able to deallocate the whole pbuf, we cannot change this
AdamGreen	0:616601bde9fb	1131	inseg.p pointer to point to any of the later pbufs in the
AdamGreen	0:616601bde9fb	1132	chain. Instead, we point the ->payload pointer in the first
AdamGreen	0:616601bde9fb	1133	pbuf to data in one of the later pbufs. We also set the
AdamGreen	0:616601bde9fb	1134	inseg.data pointer to point to the right place. This way, the
AdamGreen	0:616601bde9fb	1135	->p pointer will still point to the first pbuf, but the
AdamGreen	0:616601bde9fb	1136	->p->payload pointer will point to data in another pbuf.
AdamGreen	0:616601bde9fb	1137
AdamGreen	0:616601bde9fb	1138	After we are done with adjusting the pbuf pointers we must
AdamGreen	0:616601bde9fb	1139	adjust the ->data pointer in the seg and the segment
AdamGreen	0:616601bde9fb	1140	length.*/
AdamGreen	0:616601bde9fb	1141
AdamGreen	0:616601bde9fb	1142	off = pcb->rcv_nxt - seqno;
AdamGreen	0:616601bde9fb	1143	p = inseg.p;
AdamGreen	0:616601bde9fb	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
AdamGreen	0:616601bde9fb	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
AdamGreen	0:616601bde9fb	1146	if (inseg.p->len < off) {
AdamGreen	0:616601bde9fb	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
AdamGreen	0:616601bde9fb	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
AdamGreen	0:616601bde9fb	1149	while (p->len < off) {
AdamGreen	0:616601bde9fb	1150	off -= p->len;
AdamGreen	0:616601bde9fb	1151	/* KJM following line changed (with addition of new_tot_len var)
AdamGreen	0:616601bde9fb	1152	to fix bug #9076
AdamGreen	0:616601bde9fb	1153	inseg.p->tot_len -= p->len; */
AdamGreen	0:616601bde9fb	1154	p->tot_len = new_tot_len;
AdamGreen	0:616601bde9fb	1155	p->len = 0;
AdamGreen	0:616601bde9fb	1156	p = p->next;
AdamGreen	0:616601bde9fb	1157	}
AdamGreen	0:616601bde9fb	1158	if(pbuf_header(p, (s16_t)-off)) {
AdamGreen	0:616601bde9fb	1159	/* Do we need to cope with this failing? Assert for now */
AdamGreen	0:616601bde9fb	1160	LWIP_ASSERT("pbuf_header failed", 0);
AdamGreen	0:616601bde9fb	1161	}
AdamGreen	0:616601bde9fb	1162	} else {
AdamGreen	0:616601bde9fb	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
AdamGreen	0:616601bde9fb	1164	/* Do we need to cope with this failing? Assert for now */
AdamGreen	0:616601bde9fb	1165	LWIP_ASSERT("pbuf_header failed", 0);
AdamGreen	0:616601bde9fb	1166	}
AdamGreen	0:616601bde9fb	1167	}
AdamGreen	0:616601bde9fb	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
AdamGreen	0:616601bde9fb	1169	to fix bug #9076 */
AdamGreen	0:616601bde9fb	1170	inseg.dataptr = p->payload;
AdamGreen	0:616601bde9fb	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
AdamGreen	0:616601bde9fb	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
AdamGreen	0:616601bde9fb	1173	}
AdamGreen	0:616601bde9fb	1174	else {
AdamGreen	0:616601bde9fb	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
AdamGreen	0:616601bde9fb	1176	/* the whole segment is < rcv_nxt */
AdamGreen	0:616601bde9fb	1177	/* must be a duplicate of a packet that has already been correctly handled */
AdamGreen	0:616601bde9fb	1178
AdamGreen	0:616601bde9fb	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
AdamGreen	0:616601bde9fb	1180	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	1181	}
AdamGreen	0:616601bde9fb	1182	}
AdamGreen	0:616601bde9fb	1183
AdamGreen	0:616601bde9fb	1184	/* The sequence number must be within the window (above rcv_nxt
AdamGreen	0:616601bde9fb	1185	and below rcv_nxt + rcv_wnd) in order to be further
AdamGreen	0:616601bde9fb	1186	processed. */
AdamGreen	0:616601bde9fb	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
AdamGreen	0:616601bde9fb	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
AdamGreen	0:616601bde9fb	1189	if (pcb->rcv_nxt == seqno) {
AdamGreen	0:616601bde9fb	1190	/* The incoming segment is the next in sequence. We check if
AdamGreen	0:616601bde9fb	1191	we have to trim the end of the segment and update rcv_nxt
AdamGreen	0:616601bde9fb	1192	and pass the data to the application. */
AdamGreen	0:616601bde9fb	1193	tcplen = TCP_TCPLEN(&inseg);
AdamGreen	0:616601bde9fb	1194
AdamGreen	0:616601bde9fb	1195	if (tcplen > pcb->rcv_wnd) {
AdamGreen	0:616601bde9fb	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
AdamGreen	0:616601bde9fb	1197	("tcp_receive: other end overran receive window"
AdamGreen	0:616601bde9fb	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
AdamGreen	0:616601bde9fb	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
AdamGreen	0:616601bde9fb	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	1201	/* Must remove the FIN from the header as we're trimming
AdamGreen	0:616601bde9fb	1202	* that byte of sequence-space from the packet */
AdamGreen	0:616601bde9fb	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
AdamGreen	0:616601bde9fb	1204	}
AdamGreen	0:616601bde9fb	1205	/* Adjust length of segment to fit in the window. */
AdamGreen	0:616601bde9fb	1206	inseg.len = pcb->rcv_wnd;
AdamGreen	0:616601bde9fb	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
AdamGreen	0:616601bde9fb	1208	inseg.len -= 1;
AdamGreen	0:616601bde9fb	1209	}
AdamGreen	0:616601bde9fb	1210	pbuf_realloc(inseg.p, inseg.len);
AdamGreen	0:616601bde9fb	1211	tcplen = TCP_TCPLEN(&inseg);
AdamGreen	0:616601bde9fb	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
AdamGreen	0:616601bde9fb	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
AdamGreen	0:616601bde9fb	1214	}
AdamGreen	0:616601bde9fb	1215	#if TCP_QUEUE_OOSEQ
AdamGreen	0:616601bde9fb	1216	/* Received in-sequence data, adjust ooseq data if:
AdamGreen	0:616601bde9fb	1217	- FIN has been received or
AdamGreen	0:616601bde9fb	1218	- inseq overlaps with ooseq */
AdamGreen	0:616601bde9fb	1219	if (pcb->ooseq != NULL) {
AdamGreen	0:616601bde9fb	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
AdamGreen	0:616601bde9fb	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
AdamGreen	0:616601bde9fb	1223	/* Received in-order FIN means anything that was received
AdamGreen	0:616601bde9fb	1224	* out of order must now have been received in-order, so
AdamGreen	0:616601bde9fb	1225	* bin the ooseq queue */
AdamGreen	0:616601bde9fb	1226	while (pcb->ooseq != NULL) {
AdamGreen	0:616601bde9fb	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
AdamGreen	0:616601bde9fb	1228	pcb->ooseq = pcb->ooseq->next;
AdamGreen	0:616601bde9fb	1229	tcp_seg_free(old_ooseq);
AdamGreen	0:616601bde9fb	1230	}
AdamGreen	0:616601bde9fb	1231	}
AdamGreen	0:616601bde9fb	1232	else {
AdamGreen	0:616601bde9fb	1233	next = pcb->ooseq;
AdamGreen	0:616601bde9fb	1234	/* Remove all segments on ooseq that are covered by inseg already.
AdamGreen	0:616601bde9fb	1235	* FIN is copied from ooseq to inseg if present. */
AdamGreen	0:616601bde9fb	1236	while (next &&
AdamGreen	0:616601bde9fb	1237	TCP_SEQ_GEQ(seqno + tcplen,
AdamGreen	0:616601bde9fb	1238	next->tcphdr->seqno + next->len)) {
AdamGreen	0:616601bde9fb	1239	/* inseg cannot have FIN here (already processed above) */
AdamGreen	0:616601bde9fb	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
AdamGreen	0:616601bde9fb	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
AdamGreen	0:616601bde9fb	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
AdamGreen	0:616601bde9fb	1243	tcplen = TCP_TCPLEN(&inseg);
AdamGreen	0:616601bde9fb	1244	}
AdamGreen	0:616601bde9fb	1245	prev = next;
AdamGreen	0:616601bde9fb	1246	next = next->next;
AdamGreen	0:616601bde9fb	1247	tcp_seg_free(prev);
AdamGreen	0:616601bde9fb	1248	}
AdamGreen	0:616601bde9fb	1249	/* Now trim right side of inseg if it overlaps with the first
AdamGreen	0:616601bde9fb	1250	* segment on ooseq */
AdamGreen	0:616601bde9fb	1251	if (next &&
AdamGreen	0:616601bde9fb	1252	TCP_SEQ_GT(seqno + tcplen,
AdamGreen	0:616601bde9fb	1253	next->tcphdr->seqno)) {
AdamGreen	0:616601bde9fb	1254	/* inseg cannot have FIN here (already processed above) */
AdamGreen	0:616601bde9fb	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
AdamGreen	0:616601bde9fb	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
AdamGreen	0:616601bde9fb	1257	inseg.len -= 1;
AdamGreen	0:616601bde9fb	1258	}
AdamGreen	0:616601bde9fb	1259	pbuf_realloc(inseg.p, inseg.len);
AdamGreen	0:616601bde9fb	1260	tcplen = TCP_TCPLEN(&inseg);
AdamGreen	0:616601bde9fb	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
AdamGreen	0:616601bde9fb	1262	(seqno + tcplen) == next->tcphdr->seqno);
AdamGreen	0:616601bde9fb	1263	}
AdamGreen	0:616601bde9fb	1264	pcb->ooseq = next;
AdamGreen	0:616601bde9fb	1265	}
AdamGreen	0:616601bde9fb	1266	}
AdamGreen	0:616601bde9fb	1267	#endif /* TCP_QUEUE_OOSEQ */
AdamGreen	0:616601bde9fb	1268
AdamGreen	0:616601bde9fb	1269	pcb->rcv_nxt = seqno + tcplen;
AdamGreen	0:616601bde9fb	1270
AdamGreen	0:616601bde9fb	1271	/* Update the receiver's (our) window. */
AdamGreen	0:616601bde9fb	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
AdamGreen	0:616601bde9fb	1273	pcb->rcv_wnd -= tcplen;
AdamGreen	0:616601bde9fb	1274
AdamGreen	0:616601bde9fb	1275	tcp_update_rcv_ann_wnd(pcb);
AdamGreen	0:616601bde9fb	1276
AdamGreen	0:616601bde9fb	1277	/* If there is data in the segment, we make preparations to
AdamGreen	0:616601bde9fb	1278	pass this up to the application. The ->recv_data variable
AdamGreen	0:616601bde9fb	1279	is used for holding the pbuf that goes to the
AdamGreen	0:616601bde9fb	1280	application. The code for reassembling out-of-sequence data
AdamGreen	0:616601bde9fb	1281	chains its data on this pbuf as well.
AdamGreen	0:616601bde9fb	1282
AdamGreen	0:616601bde9fb	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
AdamGreen	0:616601bde9fb	1284	be used to indicate to the application that the remote side has
AdamGreen	0:616601bde9fb	1285	closed its end of the connection. */
AdamGreen	0:616601bde9fb	1286	if (inseg.p->tot_len > 0) {
AdamGreen	0:616601bde9fb	1287	recv_data = inseg.p;
AdamGreen	0:616601bde9fb	1288	/* Since this pbuf now is the responsibility of the
AdamGreen	0:616601bde9fb	1289	application, we delete our reference to it so that we won't
AdamGreen	0:616601bde9fb	1290	(mistakingly) deallocate it. */
AdamGreen	0:616601bde9fb	1291	inseg.p = NULL;
AdamGreen	0:616601bde9fb	1292	}
AdamGreen	0:616601bde9fb	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
AdamGreen	0:616601bde9fb	1295	recv_flags \|= TF_GOT_FIN;
AdamGreen	0:616601bde9fb	1296	}
AdamGreen	0:616601bde9fb	1297
AdamGreen	0:616601bde9fb	1298	#if TCP_QUEUE_OOSEQ
AdamGreen	0:616601bde9fb	1299	/* We now check if we have segments on the ->ooseq queue that
AdamGreen	0:616601bde9fb	1300	are now in sequence. */
AdamGreen	0:616601bde9fb	1301	while (pcb->ooseq != NULL &&
AdamGreen	0:616601bde9fb	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
AdamGreen	0:616601bde9fb	1303
AdamGreen	0:616601bde9fb	1304	cseg = pcb->ooseq;
AdamGreen	0:616601bde9fb	1305	seqno = pcb->ooseq->tcphdr->seqno;
AdamGreen	0:616601bde9fb	1306
AdamGreen	0:616601bde9fb	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
AdamGreen	0:616601bde9fb	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
AdamGreen	0:616601bde9fb	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
AdamGreen	0:616601bde9fb	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
AdamGreen	0:616601bde9fb	1311
AdamGreen	0:616601bde9fb	1312	tcp_update_rcv_ann_wnd(pcb);
AdamGreen	0:616601bde9fb	1313
AdamGreen	0:616601bde9fb	1314	if (cseg->p->tot_len > 0) {
AdamGreen	0:616601bde9fb	1315	/* Chain this pbuf onto the pbuf that we will pass to
AdamGreen	0:616601bde9fb	1316	the application. */
AdamGreen	0:616601bde9fb	1317	if (recv_data) {
AdamGreen	0:616601bde9fb	1318	pbuf_cat(recv_data, cseg->p);
AdamGreen	0:616601bde9fb	1319	} else {
AdamGreen	0:616601bde9fb	1320	recv_data = cseg->p;
AdamGreen	0:616601bde9fb	1321	}
AdamGreen	0:616601bde9fb	1322	cseg->p = NULL;
AdamGreen	0:616601bde9fb	1323	}
AdamGreen	0:616601bde9fb	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
AdamGreen	0:616601bde9fb	1326	recv_flags \|= TF_GOT_FIN;
AdamGreen	0:616601bde9fb	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
AdamGreen	0:616601bde9fb	1328	pcb->state = CLOSE_WAIT;
AdamGreen	0:616601bde9fb	1329	}
AdamGreen	0:616601bde9fb	1330	}
AdamGreen	0:616601bde9fb	1331
AdamGreen	0:616601bde9fb	1332	pcb->ooseq = cseg->next;
AdamGreen	0:616601bde9fb	1333	tcp_seg_free(cseg);
AdamGreen	0:616601bde9fb	1334	}
AdamGreen	0:616601bde9fb	1335	#endif /* TCP_QUEUE_OOSEQ */
AdamGreen	0:616601bde9fb	1336
AdamGreen	0:616601bde9fb	1337
AdamGreen	0:616601bde9fb	1338	/* Acknowledge the segment(s). */
AdamGreen	0:616601bde9fb	1339	tcp_ack(pcb);
AdamGreen	0:616601bde9fb	1340
AdamGreen	0:616601bde9fb	1341	} else {
AdamGreen	0:616601bde9fb	1342	/* We get here if the incoming segment is out-of-sequence. */
AdamGreen	0:616601bde9fb	1343	tcp_send_empty_ack(pcb);
AdamGreen	0:616601bde9fb	1344	#if TCP_QUEUE_OOSEQ
AdamGreen	0:616601bde9fb	1345	/* We queue the segment on the ->ooseq queue. */
AdamGreen	0:616601bde9fb	1346	if (pcb->ooseq == NULL) {
AdamGreen	0:616601bde9fb	1347	pcb->ooseq = tcp_seg_copy(&inseg);
AdamGreen	0:616601bde9fb	1348	} else {
AdamGreen	0:616601bde9fb	1349	/* If the queue is not empty, we walk through the queue and
AdamGreen	0:616601bde9fb	1350	try to find a place where the sequence number of the
AdamGreen	0:616601bde9fb	1351	incoming segment is between the sequence numbers of the
AdamGreen	0:616601bde9fb	1352	previous and the next segment on the ->ooseq queue. That is
AdamGreen	0:616601bde9fb	1353	the place where we put the incoming segment. If needed, we
AdamGreen	0:616601bde9fb	1354	trim the second edges of the previous and the incoming
AdamGreen	0:616601bde9fb	1355	segment so that it will fit into the sequence.
AdamGreen	0:616601bde9fb	1356
AdamGreen	0:616601bde9fb	1357	If the incoming segment has the same sequence number as a
AdamGreen	0:616601bde9fb	1358	segment on the ->ooseq queue, we discard the segment that
AdamGreen	0:616601bde9fb	1359	contains less data. */
AdamGreen	0:616601bde9fb	1360
AdamGreen	0:616601bde9fb	1361	prev = NULL;
AdamGreen	0:616601bde9fb	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
AdamGreen	0:616601bde9fb	1363	if (seqno == next->tcphdr->seqno) {
AdamGreen	0:616601bde9fb	1364	/* The sequence number of the incoming segment is the
AdamGreen	0:616601bde9fb	1365	same as the sequence number of the segment on
AdamGreen	0:616601bde9fb	1366	->ooseq. We check the lengths to see which one to
AdamGreen	0:616601bde9fb	1367	discard. */
AdamGreen	0:616601bde9fb	1368	if (inseg.len > next->len) {
AdamGreen	0:616601bde9fb	1369	/* The incoming segment is larger than the old
AdamGreen	0:616601bde9fb	1370	segment. We replace some segments with the new
AdamGreen	0:616601bde9fb	1371	one. */
AdamGreen	0:616601bde9fb	1372	cseg = tcp_seg_copy(&inseg);
AdamGreen	0:616601bde9fb	1373	if (cseg != NULL) {
AdamGreen	0:616601bde9fb	1374	if (prev != NULL) {
AdamGreen	0:616601bde9fb	1375	prev->next = cseg;
AdamGreen	0:616601bde9fb	1376	} else {
AdamGreen	0:616601bde9fb	1377	pcb->ooseq = cseg;
AdamGreen	0:616601bde9fb	1378	}
AdamGreen	0:616601bde9fb	1379	tcp_oos_insert_segment(cseg, next);
AdamGreen	0:616601bde9fb	1380	}
AdamGreen	0:616601bde9fb	1381	break;
AdamGreen	0:616601bde9fb	1382	} else {
AdamGreen	0:616601bde9fb	1383	/* Either the lenghts are the same or the incoming
AdamGreen	0:616601bde9fb	1384	segment was smaller than the old one; in either
AdamGreen	0:616601bde9fb	1385	case, we ditch the incoming segment. */
AdamGreen	0:616601bde9fb	1386	break;
AdamGreen	0:616601bde9fb	1387	}
AdamGreen	0:616601bde9fb	1388	} else {
AdamGreen	0:616601bde9fb	1389	if (prev == NULL) {
AdamGreen	0:616601bde9fb	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
AdamGreen	0:616601bde9fb	1391	/* The sequence number of the incoming segment is lower
AdamGreen	0:616601bde9fb	1392	than the sequence number of the first segment on the
AdamGreen	0:616601bde9fb	1393	queue. We put the incoming segment first on the
AdamGreen	0:616601bde9fb	1394	queue. */
AdamGreen	0:616601bde9fb	1395	cseg = tcp_seg_copy(&inseg);
AdamGreen	0:616601bde9fb	1396	if (cseg != NULL) {
AdamGreen	0:616601bde9fb	1397	pcb->ooseq = cseg;
AdamGreen	0:616601bde9fb	1398	tcp_oos_insert_segment(cseg, next);
AdamGreen	0:616601bde9fb	1399	}
AdamGreen	0:616601bde9fb	1400	break;
AdamGreen	0:616601bde9fb	1401	}
AdamGreen	0:616601bde9fb	1402	} else {
AdamGreen	0:616601bde9fb	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
AdamGreen	0:616601bde9fb	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
AdamGreen	0:616601bde9fb	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
AdamGreen	0:616601bde9fb	1406	/* The sequence number of the incoming segment is in
AdamGreen	0:616601bde9fb	1407	between the sequence numbers of the previous and
AdamGreen	0:616601bde9fb	1408	the next segment on ->ooseq. We trim trim the previous
AdamGreen	0:616601bde9fb	1409	segment, delete next segments that included in received segment
AdamGreen	0:616601bde9fb	1410	and trim received, if needed. */
AdamGreen	0:616601bde9fb	1411	cseg = tcp_seg_copy(&inseg);
AdamGreen	0:616601bde9fb	1412	if (cseg != NULL) {
AdamGreen	0:616601bde9fb	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
AdamGreen	0:616601bde9fb	1414	/* We need to trim the prev segment. */
AdamGreen	0:616601bde9fb	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
AdamGreen	0:616601bde9fb	1416	pbuf_realloc(prev->p, prev->len);
AdamGreen	0:616601bde9fb	1417	}
AdamGreen	0:616601bde9fb	1418	prev->next = cseg;
AdamGreen	0:616601bde9fb	1419	tcp_oos_insert_segment(cseg, next);
AdamGreen	0:616601bde9fb	1420	}
AdamGreen	0:616601bde9fb	1421	break;
AdamGreen	0:616601bde9fb	1422	}
AdamGreen	0:616601bde9fb	1423	}
AdamGreen	0:616601bde9fb	1424	/* If the "next" segment is the last segment on the
AdamGreen	0:616601bde9fb	1425	ooseq queue, we add the incoming segment to the end
AdamGreen	0:616601bde9fb	1426	of the list. */
AdamGreen	0:616601bde9fb	1427	if (next->next == NULL &&
AdamGreen	0:616601bde9fb	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
AdamGreen	0:616601bde9fb	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	1430	/* segment "next" already contains all data */
AdamGreen	0:616601bde9fb	1431	break;
AdamGreen	0:616601bde9fb	1432	}
AdamGreen	0:616601bde9fb	1433	next->next = tcp_seg_copy(&inseg);
AdamGreen	0:616601bde9fb	1434	if (next->next != NULL) {
AdamGreen	0:616601bde9fb	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
AdamGreen	0:616601bde9fb	1436	/* We need to trim the last segment. */
AdamGreen	0:616601bde9fb	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
AdamGreen	0:616601bde9fb	1438	pbuf_realloc(next->p, next->len);
AdamGreen	0:616601bde9fb	1439	}
AdamGreen	0:616601bde9fb	1440	/* check if the remote side overruns our receive window */
AdamGreen	0:616601bde9fb	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
AdamGreen	0:616601bde9fb	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
AdamGreen	0:616601bde9fb	1443	("tcp_receive: other end overran receive window"
AdamGreen	0:616601bde9fb	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
AdamGreen	0:616601bde9fb	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
AdamGreen	0:616601bde9fb	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
AdamGreen	0:616601bde9fb	1447	/* Must remove the FIN from the header as we're trimming
AdamGreen	0:616601bde9fb	1448	* that byte of sequence-space from the packet */
AdamGreen	0:616601bde9fb	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
AdamGreen	0:616601bde9fb	1450	}
AdamGreen	0:616601bde9fb	1451	/* Adjust length of segment to fit in the window. */
AdamGreen	0:616601bde9fb	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
AdamGreen	0:616601bde9fb	1453	pbuf_realloc(next->next->p, next->next->len);
AdamGreen	0:616601bde9fb	1454	tcplen = TCP_TCPLEN(next->next);
AdamGreen	0:616601bde9fb	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
AdamGreen	0:616601bde9fb	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
AdamGreen	0:616601bde9fb	1457	}
AdamGreen	0:616601bde9fb	1458	}
AdamGreen	0:616601bde9fb	1459	break;
AdamGreen	0:616601bde9fb	1460	}
AdamGreen	0:616601bde9fb	1461	}
AdamGreen	0:616601bde9fb	1462	prev = next;
AdamGreen	0:616601bde9fb	1463	}
AdamGreen	0:616601bde9fb	1464	}
AdamGreen	0:616601bde9fb	1465	#endif /* TCP_QUEUE_OOSEQ */
AdamGreen	0:616601bde9fb	1466
AdamGreen	0:616601bde9fb	1467	}
AdamGreen	0:616601bde9fb	1468	} else {
AdamGreen	0:616601bde9fb	1469	/* The incoming segment is not withing the window. */
AdamGreen	0:616601bde9fb	1470	tcp_send_empty_ack(pcb);
AdamGreen	0:616601bde9fb	1471	}
AdamGreen	0:616601bde9fb	1472	} else {
AdamGreen	0:616601bde9fb	1473	/* Segments with length 0 is taken care of here. Segments that
AdamGreen	0:616601bde9fb	1474	fall out of the window are ACKed. */
AdamGreen	0:616601bde9fb	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
AdamGreen	0:616601bde9fb	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
AdamGreen	0:616601bde9fb	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
AdamGreen	0:616601bde9fb	1478	tcp_ack_now(pcb);
AdamGreen	0:616601bde9fb	1479	}
AdamGreen	0:616601bde9fb	1480	}
AdamGreen	0:616601bde9fb	1481	}
AdamGreen	0:616601bde9fb	1482
AdamGreen	0:616601bde9fb	1483	/**
AdamGreen	0:616601bde9fb	1484	* Parses the options contained in the incoming segment.
AdamGreen	0:616601bde9fb	1485	*
AdamGreen	0:616601bde9fb	1486	* Called from tcp_listen_input() and tcp_process().
AdamGreen	0:616601bde9fb	1487	* Currently, only the MSS option is supported!
AdamGreen	0:616601bde9fb	1488	*
AdamGreen	0:616601bde9fb	1489	* @param pcb the tcp_pcb for which a segment arrived
AdamGreen	0:616601bde9fb	1490	*/
AdamGreen	0:616601bde9fb	1491	static void
AdamGreen	0:616601bde9fb	1492	tcp_parseopt(struct tcp_pcb *pcb)
AdamGreen	0:616601bde9fb	1493	{
AdamGreen	0:616601bde9fb	1494	u16_t c, max_c;
AdamGreen	0:616601bde9fb	1495	u16_t mss;
AdamGreen	0:616601bde9fb	1496	u8_t *opts, opt;
AdamGreen	0:616601bde9fb	1497	#if LWIP_TCP_TIMESTAMPS
AdamGreen	0:616601bde9fb	1498	u32_t tsval;
AdamGreen	0:616601bde9fb	1499	#endif
AdamGreen	0:616601bde9fb	1500
AdamGreen	0:616601bde9fb	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
AdamGreen	0:616601bde9fb	1502
AdamGreen	0:616601bde9fb	1503	/* Parse the TCP MSS option, if present. */
AdamGreen	0:616601bde9fb	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
AdamGreen	0:616601bde9fb	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
AdamGreen	0:616601bde9fb	1506	for (c = 0; c < max_c; ) {
AdamGreen	0:616601bde9fb	1507	opt = opts[c];
AdamGreen	0:616601bde9fb	1508	switch (opt) {
AdamGreen	0:616601bde9fb	1509	case 0x00:
AdamGreen	0:616601bde9fb	1510	/* End of options. */
AdamGreen	0:616601bde9fb	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
AdamGreen	0:616601bde9fb	1512	return;
AdamGreen	0:616601bde9fb	1513	case 0x01:
AdamGreen	0:616601bde9fb	1514	/* NOP option. */
AdamGreen	0:616601bde9fb	1515	++c;
AdamGreen	0:616601bde9fb	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
AdamGreen	0:616601bde9fb	1517	break;
AdamGreen	0:616601bde9fb	1518	case 0x02:
AdamGreen	0:616601bde9fb	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
AdamGreen	0:616601bde9fb	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
AdamGreen	0:616601bde9fb	1521	/* Bad length */
AdamGreen	0:616601bde9fb	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
AdamGreen	0:616601bde9fb	1523	return;
AdamGreen	0:616601bde9fb	1524	}
AdamGreen	0:616601bde9fb	1525	/* An MSS option with the right option length. */
AdamGreen	0:616601bde9fb	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
AdamGreen	0:616601bde9fb	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
AdamGreen	0:616601bde9fb	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
AdamGreen	0:616601bde9fb	1529	/* Advance to next option */
AdamGreen	0:616601bde9fb	1530	c += 0x04;
AdamGreen	0:616601bde9fb	1531	break;
AdamGreen	0:616601bde9fb	1532	#if LWIP_TCP_TIMESTAMPS
AdamGreen	0:616601bde9fb	1533	case 0x08:
AdamGreen	0:616601bde9fb	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
AdamGreen	0:616601bde9fb	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
AdamGreen	0:616601bde9fb	1536	/* Bad length */
AdamGreen	0:616601bde9fb	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
AdamGreen	0:616601bde9fb	1538	return;
AdamGreen	0:616601bde9fb	1539	}
AdamGreen	0:616601bde9fb	1540	/* TCP timestamp option with valid length */
AdamGreen	0:616601bde9fb	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
AdamGreen	0:616601bde9fb	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
AdamGreen	0:616601bde9fb	1543	if (flags & TCP_SYN) {
AdamGreen	0:616601bde9fb	1544	pcb->ts_recent = ntohl(tsval);
AdamGreen	0:616601bde9fb	1545	pcb->flags \|= TF_TIMESTAMP;
AdamGreen	0:616601bde9fb	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
AdamGreen	0:616601bde9fb	1547	pcb->ts_recent = ntohl(tsval);
AdamGreen	0:616601bde9fb	1548	}
AdamGreen	0:616601bde9fb	1549	/* Advance to next option */
AdamGreen	0:616601bde9fb	1550	c += 0x0A;
AdamGreen	0:616601bde9fb	1551	break;
AdamGreen	0:616601bde9fb	1552	#endif
AdamGreen	0:616601bde9fb	1553	default:
AdamGreen	0:616601bde9fb	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
AdamGreen	0:616601bde9fb	1555	if (opts[c + 1] == 0) {
AdamGreen	0:616601bde9fb	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
AdamGreen	0:616601bde9fb	1557	/* If the length field is zero, the options are malformed
AdamGreen	0:616601bde9fb	1558	and we don't process them further. */
AdamGreen	0:616601bde9fb	1559	return;
AdamGreen	0:616601bde9fb	1560	}
AdamGreen	0:616601bde9fb	1561	/* All other options have a length field, so that we easily
AdamGreen	0:616601bde9fb	1562	can skip past them. */
AdamGreen	0:616601bde9fb	1563	c += opts[c + 1];
AdamGreen	0:616601bde9fb	1564	}
AdamGreen	0:616601bde9fb	1565	}
AdamGreen	0:616601bde9fb	1566	}
AdamGreen	0:616601bde9fb	1567	}
AdamGreen	0:616601bde9fb	1568
AdamGreen	0:616601bde9fb	1569	#endif /* LWIP_TCP */

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	23 Feb 2012
Imports:	113
Forks:	0
Commits:	2
Dependents:	0
Dependencies:	4
Followers:	6

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