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lwip/core/tcp_in.c@0:d7bd7384a37c, 2016-12-07 (annotated)

Committer:: grzemich
Date:: Wed Dec 07 23:47:50 2016 +0000
Revision:: 0:d7bd7384a37c

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User	Revision	Line number	New contents of line
grzemich	0:d7bd7384a37c	1	/**
grzemich	0:d7bd7384a37c	2	* @file
grzemich	0:d7bd7384a37c	3	* Transmission Control Protocol, incoming traffic
grzemich	0:d7bd7384a37c	4	*
grzemich	0:d7bd7384a37c	5	* The input processing functions of the TCP layer.
grzemich	0:d7bd7384a37c	6	*
grzemich	0:d7bd7384a37c	7	* These functions are generally called in the order (ip_input() ->)
grzemich	0:d7bd7384a37c	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
grzemich	0:d7bd7384a37c	9	*
grzemich	0:d7bd7384a37c	10	*/
grzemich	0:d7bd7384a37c	11
grzemich	0:d7bd7384a37c	12	/*
grzemich	0:d7bd7384a37c	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
grzemich	0:d7bd7384a37c	14	* All rights reserved.
grzemich	0:d7bd7384a37c	15	*
grzemich	0:d7bd7384a37c	16	* Redistribution and use in source and binary forms, with or without modification,
grzemich	0:d7bd7384a37c	17	* are permitted provided that the following conditions are met:
grzemich	0:d7bd7384a37c	18	*
grzemich	0:d7bd7384a37c	19	* 1. Redistributions of source code must retain the above copyright notice,
grzemich	0:d7bd7384a37c	20	* this list of conditions and the following disclaimer.
grzemich	0:d7bd7384a37c	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
grzemich	0:d7bd7384a37c	22	* this list of conditions and the following disclaimer in the documentation
grzemich	0:d7bd7384a37c	23	* and/or other materials provided with the distribution.
grzemich	0:d7bd7384a37c	24	* 3. The name of the author may not be used to endorse or promote products
grzemich	0:d7bd7384a37c	25	* derived from this software without specific prior written permission.
grzemich	0:d7bd7384a37c	26	*
grzemich	0:d7bd7384a37c	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
grzemich	0:d7bd7384a37c	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
grzemich	0:d7bd7384a37c	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
grzemich	0:d7bd7384a37c	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
grzemich	0:d7bd7384a37c	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
grzemich	0:d7bd7384a37c	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
grzemich	0:d7bd7384a37c	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
grzemich	0:d7bd7384a37c	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
grzemich	0:d7bd7384a37c	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
grzemich	0:d7bd7384a37c	36	* OF SUCH DAMAGE.
grzemich	0:d7bd7384a37c	37	*
grzemich	0:d7bd7384a37c	38	* This file is part of the lwIP TCP/IP stack.
grzemich	0:d7bd7384a37c	39	*
grzemich	0:d7bd7384a37c	40	* Author: Adam Dunkels <adam@sics.se>
grzemich	0:d7bd7384a37c	41	*
grzemich	0:d7bd7384a37c	42	*/
grzemich	0:d7bd7384a37c	43
grzemich	0:d7bd7384a37c	44	#include "lwip/opt.h"
grzemich	0:d7bd7384a37c	45
grzemich	0:d7bd7384a37c	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
grzemich	0:d7bd7384a37c	47
grzemich	0:d7bd7384a37c	48	#include "lwip/tcp_impl.h"
grzemich	0:d7bd7384a37c	49	#include "lwip/def.h"
grzemich	0:d7bd7384a37c	50	#include "lwip/ip_addr.h"
grzemich	0:d7bd7384a37c	51	#include "lwip/netif.h"
grzemich	0:d7bd7384a37c	52	#include "lwip/mem.h"
grzemich	0:d7bd7384a37c	53	#include "lwip/memp.h"
grzemich	0:d7bd7384a37c	54	#include "lwip/inet_chksum.h"
grzemich	0:d7bd7384a37c	55	#include "lwip/stats.h"
grzemich	0:d7bd7384a37c	56	#include "lwip/snmp.h"
grzemich	0:d7bd7384a37c	57	#include "arch/perf.h"
grzemich	0:d7bd7384a37c	58
grzemich	0:d7bd7384a37c	59	/* These variables are global to all functions involved in the input
grzemich	0:d7bd7384a37c	60	processing of TCP segments. They are set by the tcp_input()
grzemich	0:d7bd7384a37c	61	function. */
grzemich	0:d7bd7384a37c	62	static struct tcp_seg inseg;
grzemich	0:d7bd7384a37c	63	static struct tcp_hdr *tcphdr;
grzemich	0:d7bd7384a37c	64	static struct ip_hdr *iphdr;
grzemich	0:d7bd7384a37c	65	static u32_t seqno, ackno;
grzemich	0:d7bd7384a37c	66	static u8_t flags;
grzemich	0:d7bd7384a37c	67	static u16_t tcplen;
grzemich	0:d7bd7384a37c	68
grzemich	0:d7bd7384a37c	69	static u8_t recv_flags;
grzemich	0:d7bd7384a37c	70	static struct pbuf *recv_data;
grzemich	0:d7bd7384a37c	71
grzemich	0:d7bd7384a37c	72	struct tcp_pcb *tcp_input_pcb;
grzemich	0:d7bd7384a37c	73
grzemich	0:d7bd7384a37c	74	/* Forward declarations. */
grzemich	0:d7bd7384a37c	75	static err_t tcp_process(struct tcp_pcb *pcb);
grzemich	0:d7bd7384a37c	76	static void tcp_receive(struct tcp_pcb *pcb);
grzemich	0:d7bd7384a37c	77	static void tcp_parseopt(struct tcp_pcb *pcb);
grzemich	0:d7bd7384a37c	78
grzemich	0:d7bd7384a37c	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
grzemich	0:d7bd7384a37c	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
grzemich	0:d7bd7384a37c	81
grzemich	0:d7bd7384a37c	82	/**
grzemich	0:d7bd7384a37c	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
grzemich	0:d7bd7384a37c	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
grzemich	0:d7bd7384a37c	85	* the TCP finite state machine. This function is called by the IP layer (in
grzemich	0:d7bd7384a37c	86	* ip_input()).
grzemich	0:d7bd7384a37c	87	*
grzemich	0:d7bd7384a37c	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
grzemich	0:d7bd7384a37c	89	* @param inp network interface on which this segment was received
grzemich	0:d7bd7384a37c	90	*/
grzemich	0:d7bd7384a37c	91	void
grzemich	0:d7bd7384a37c	92	tcp_input(struct pbuf p, struct netif inp)
grzemich	0:d7bd7384a37c	93	{
grzemich	0:d7bd7384a37c	94	struct tcp_pcb pcb, prev;
grzemich	0:d7bd7384a37c	95	struct tcp_pcb_listen *lpcb;
grzemich	0:d7bd7384a37c	96	#if SO_REUSE
grzemich	0:d7bd7384a37c	97	struct tcp_pcb *lpcb_prev = NULL;
grzemich	0:d7bd7384a37c	98	struct tcp_pcb_listen *lpcb_any = NULL;
grzemich	0:d7bd7384a37c	99	#endif /* SO_REUSE */
grzemich	0:d7bd7384a37c	100	u8_t hdrlen;
grzemich	0:d7bd7384a37c	101	err_t err;
grzemich	0:d7bd7384a37c	102
grzemich	0:d7bd7384a37c	103	PERF_START;
grzemich	0:d7bd7384a37c	104
grzemich	0:d7bd7384a37c	105	TCP_STATS_INC(tcp.recv);
grzemich	0:d7bd7384a37c	106	snmp_inc_tcpinsegs();
grzemich	0:d7bd7384a37c	107
grzemich	0:d7bd7384a37c	108	iphdr = (struct ip_hdr *)p->payload;
grzemich	0:d7bd7384a37c	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
grzemich	0:d7bd7384a37c	110
grzemich	0:d7bd7384a37c	111	#if TCP_INPUT_DEBUG
grzemich	0:d7bd7384a37c	112	tcp_debug_print(tcphdr);
grzemich	0:d7bd7384a37c	113	#endif
grzemich	0:d7bd7384a37c	114
grzemich	0:d7bd7384a37c	115	/* remove header from payload */
grzemich	0:d7bd7384a37c	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
grzemich	0:d7bd7384a37c	117	/* drop short packets */
grzemich	0:d7bd7384a37c	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
grzemich	0:d7bd7384a37c	119	TCP_STATS_INC(tcp.lenerr);
grzemich	0:d7bd7384a37c	120	TCP_STATS_INC(tcp.drop);
grzemich	0:d7bd7384a37c	121	snmp_inc_tcpinerrs();
grzemich	0:d7bd7384a37c	122	pbuf_free(p);
grzemich	0:d7bd7384a37c	123	return;
grzemich	0:d7bd7384a37c	124	}
grzemich	0:d7bd7384a37c	125
grzemich	0:d7bd7384a37c	126	/* Don't even process incoming broadcasts/multicasts. */
grzemich	0:d7bd7384a37c	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
grzemich	0:d7bd7384a37c	128	ip_addr_ismulticast(&current_iphdr_dest)) {
grzemich	0:d7bd7384a37c	129	TCP_STATS_INC(tcp.proterr);
grzemich	0:d7bd7384a37c	130	TCP_STATS_INC(tcp.drop);
grzemich	0:d7bd7384a37c	131	snmp_inc_tcpinerrs();
grzemich	0:d7bd7384a37c	132	pbuf_free(p);
grzemich	0:d7bd7384a37c	133	return;
grzemich	0:d7bd7384a37c	134	}
grzemich	0:d7bd7384a37c	135
grzemich	0:d7bd7384a37c	136	#if CHECKSUM_CHECK_TCP
grzemich	0:d7bd7384a37c	137	/* Verify TCP checksum. */
grzemich	0:d7bd7384a37c	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
grzemich	0:d7bd7384a37c	139	IP_PROTO_TCP, p->tot_len) != 0) {
grzemich	0:d7bd7384a37c	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
grzemich	0:d7bd7384a37c	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
grzemich	0:d7bd7384a37c	142	IP_PROTO_TCP, p->tot_len)));
grzemich	0:d7bd7384a37c	143	#if TCP_DEBUG
grzemich	0:d7bd7384a37c	144	tcp_debug_print(tcphdr);
grzemich	0:d7bd7384a37c	145	#endif /* TCP_DEBUG */
grzemich	0:d7bd7384a37c	146	TCP_STATS_INC(tcp.chkerr);
grzemich	0:d7bd7384a37c	147	TCP_STATS_INC(tcp.drop);
grzemich	0:d7bd7384a37c	148	snmp_inc_tcpinerrs();
grzemich	0:d7bd7384a37c	149	pbuf_free(p);
grzemich	0:d7bd7384a37c	150	return;
grzemich	0:d7bd7384a37c	151	}
grzemich	0:d7bd7384a37c	152	#endif
grzemich	0:d7bd7384a37c	153
grzemich	0:d7bd7384a37c	154	/* Move the payload pointer in the pbuf so that it points to the
grzemich	0:d7bd7384a37c	155	TCP data instead of the TCP header. */
grzemich	0:d7bd7384a37c	156	hdrlen = TCPH_HDRLEN(tcphdr);
grzemich	0:d7bd7384a37c	157	if(pbuf_header(p, -(hdrlen * 4))){
grzemich	0:d7bd7384a37c	158	/* drop short packets */
grzemich	0:d7bd7384a37c	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
grzemich	0:d7bd7384a37c	160	TCP_STATS_INC(tcp.lenerr);
grzemich	0:d7bd7384a37c	161	TCP_STATS_INC(tcp.drop);
grzemich	0:d7bd7384a37c	162	snmp_inc_tcpinerrs();
grzemich	0:d7bd7384a37c	163	pbuf_free(p);
grzemich	0:d7bd7384a37c	164	return;
grzemich	0:d7bd7384a37c	165	}
grzemich	0:d7bd7384a37c	166
grzemich	0:d7bd7384a37c	167	/* Convert fields in TCP header to host byte order. */
grzemich	0:d7bd7384a37c	168	tcphdr->src = ntohs(tcphdr->src);
grzemich	0:d7bd7384a37c	169	tcphdr->dest = ntohs(tcphdr->dest);
grzemich	0:d7bd7384a37c	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
grzemich	0:d7bd7384a37c	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
grzemich	0:d7bd7384a37c	172	tcphdr->wnd = ntohs(tcphdr->wnd);
grzemich	0:d7bd7384a37c	173
grzemich	0:d7bd7384a37c	174	flags = TCPH_FLAGS(tcphdr);
grzemich	0:d7bd7384a37c	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
grzemich	0:d7bd7384a37c	176
grzemich	0:d7bd7384a37c	177	/* Demultiplex an incoming segment. First, we check if it is destined
grzemich	0:d7bd7384a37c	178	for an active connection. */
grzemich	0:d7bd7384a37c	179	prev = NULL;
grzemich	0:d7bd7384a37c	180
grzemich	0:d7bd7384a37c	181
grzemich	0:d7bd7384a37c	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
grzemich	0:d7bd7384a37c	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
grzemich	0:d7bd7384a37c	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
grzemich	0:d7bd7384a37c	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
grzemich	0:d7bd7384a37c	186	if (pcb->remote_port == tcphdr->src &&
grzemich	0:d7bd7384a37c	187	pcb->local_port == tcphdr->dest &&
grzemich	0:d7bd7384a37c	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
grzemich	0:d7bd7384a37c	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
grzemich	0:d7bd7384a37c	190
grzemich	0:d7bd7384a37c	191	/* Move this PCB to the front of the list so that subsequent
grzemich	0:d7bd7384a37c	192	lookups will be faster (we exploit locality in TCP segment
grzemich	0:d7bd7384a37c	193	arrivals). */
grzemich	0:d7bd7384a37c	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
grzemich	0:d7bd7384a37c	195	if (prev != NULL) {
grzemich	0:d7bd7384a37c	196	prev->next = pcb->next;
grzemich	0:d7bd7384a37c	197	pcb->next = tcp_active_pcbs;
grzemich	0:d7bd7384a37c	198	tcp_active_pcbs = pcb;
grzemich	0:d7bd7384a37c	199	}
grzemich	0:d7bd7384a37c	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
grzemich	0:d7bd7384a37c	201	break;
grzemich	0:d7bd7384a37c	202	}
grzemich	0:d7bd7384a37c	203	prev = pcb;
grzemich	0:d7bd7384a37c	204	}
grzemich	0:d7bd7384a37c	205
grzemich	0:d7bd7384a37c	206	if (pcb == NULL) {
grzemich	0:d7bd7384a37c	207	/* If it did not go to an active connection, we check the connections
grzemich	0:d7bd7384a37c	208	in the TIME-WAIT state. */
grzemich	0:d7bd7384a37c	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
grzemich	0:d7bd7384a37c	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
grzemich	0:d7bd7384a37c	211	if (pcb->remote_port == tcphdr->src &&
grzemich	0:d7bd7384a37c	212	pcb->local_port == tcphdr->dest &&
grzemich	0:d7bd7384a37c	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
grzemich	0:d7bd7384a37c	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
grzemich	0:d7bd7384a37c	215	/* We don't really care enough to move this PCB to the front
grzemich	0:d7bd7384a37c	216	of the list since we are not very likely to receive that
grzemich	0:d7bd7384a37c	217	many segments for connections in TIME-WAIT. */
grzemich	0:d7bd7384a37c	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
grzemich	0:d7bd7384a37c	219	tcp_timewait_input(pcb);
grzemich	0:d7bd7384a37c	220	pbuf_free(p);
grzemich	0:d7bd7384a37c	221	return;
grzemich	0:d7bd7384a37c	222	}
grzemich	0:d7bd7384a37c	223	}
grzemich	0:d7bd7384a37c	224
grzemich	0:d7bd7384a37c	225	/* Finally, if we still did not get a match, we check all PCBs that
grzemich	0:d7bd7384a37c	226	are LISTENing for incoming connections. */
grzemich	0:d7bd7384a37c	227	prev = NULL;
grzemich	0:d7bd7384a37c	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
grzemich	0:d7bd7384a37c	229	if (lpcb->local_port == tcphdr->dest) {
grzemich	0:d7bd7384a37c	230	#if SO_REUSE
grzemich	0:d7bd7384a37c	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
grzemich	0:d7bd7384a37c	232	/* found an exact match */
grzemich	0:d7bd7384a37c	233	break;
grzemich	0:d7bd7384a37c	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
grzemich	0:d7bd7384a37c	235	/* found an ANY-match */
grzemich	0:d7bd7384a37c	236	lpcb_any = lpcb;
grzemich	0:d7bd7384a37c	237	lpcb_prev = prev;
grzemich	0:d7bd7384a37c	238	}
grzemich	0:d7bd7384a37c	239	#else /* SO_REUSE */
grzemich	0:d7bd7384a37c	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
grzemich	0:d7bd7384a37c	241	ip_addr_isany(&(lpcb->local_ip))) {
grzemich	0:d7bd7384a37c	242	/* found a match */
grzemich	0:d7bd7384a37c	243	break;
grzemich	0:d7bd7384a37c	244	}
grzemich	0:d7bd7384a37c	245	#endif /* SO_REUSE */
grzemich	0:d7bd7384a37c	246	}
grzemich	0:d7bd7384a37c	247	prev = (struct tcp_pcb *)lpcb;
grzemich	0:d7bd7384a37c	248	}
grzemich	0:d7bd7384a37c	249	#if SO_REUSE
grzemich	0:d7bd7384a37c	250	/* first try specific local IP */
grzemich	0:d7bd7384a37c	251	if (lpcb == NULL) {
grzemich	0:d7bd7384a37c	252	/* only pass to ANY if no specific local IP has been found */
grzemich	0:d7bd7384a37c	253	lpcb = lpcb_any;
grzemich	0:d7bd7384a37c	254	prev = lpcb_prev;
grzemich	0:d7bd7384a37c	255	}
grzemich	0:d7bd7384a37c	256	#endif /* SO_REUSE */
grzemich	0:d7bd7384a37c	257	if (lpcb != NULL) {
grzemich	0:d7bd7384a37c	258	/* Move this PCB to the front of the list so that subsequent
grzemich	0:d7bd7384a37c	259	lookups will be faster (we exploit locality in TCP segment
grzemich	0:d7bd7384a37c	260	arrivals). */
grzemich	0:d7bd7384a37c	261	if (prev != NULL) {
grzemich	0:d7bd7384a37c	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
grzemich	0:d7bd7384a37c	263	/* our successor is the remainder of the listening list */
grzemich	0:d7bd7384a37c	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
grzemich	0:d7bd7384a37c	265	/* put this listening pcb at the head of the listening list */
grzemich	0:d7bd7384a37c	266	tcp_listen_pcbs.listen_pcbs = lpcb;
grzemich	0:d7bd7384a37c	267	}
grzemich	0:d7bd7384a37c	268
grzemich	0:d7bd7384a37c	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
grzemich	0:d7bd7384a37c	270	tcp_listen_input(lpcb);
grzemich	0:d7bd7384a37c	271	pbuf_free(p);
grzemich	0:d7bd7384a37c	272	return;
grzemich	0:d7bd7384a37c	273	}
grzemich	0:d7bd7384a37c	274	}
grzemich	0:d7bd7384a37c	275
grzemich	0:d7bd7384a37c	276	#if TCP_INPUT_DEBUG
grzemich	0:d7bd7384a37c	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
grzemich	0:d7bd7384a37c	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
grzemich	0:d7bd7384a37c	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
grzemich	0:d7bd7384a37c	280	#endif /* TCP_INPUT_DEBUG */
grzemich	0:d7bd7384a37c	281
grzemich	0:d7bd7384a37c	282
grzemich	0:d7bd7384a37c	283	if (pcb != NULL) {
grzemich	0:d7bd7384a37c	284	/* The incoming segment belongs to a connection. */
grzemich	0:d7bd7384a37c	285	#if TCP_INPUT_DEBUG
grzemich	0:d7bd7384a37c	286	#if TCP_DEBUG
grzemich	0:d7bd7384a37c	287	tcp_debug_print_state(pcb->state);
grzemich	0:d7bd7384a37c	288	#endif /* TCP_DEBUG */
grzemich	0:d7bd7384a37c	289	#endif /* TCP_INPUT_DEBUG */
grzemich	0:d7bd7384a37c	290
grzemich	0:d7bd7384a37c	291	/* Set up a tcp_seg structure. */
grzemich	0:d7bd7384a37c	292	inseg.next = NULL;
grzemich	0:d7bd7384a37c	293	inseg.len = p->tot_len;
grzemich	0:d7bd7384a37c	294	inseg.p = p;
grzemich	0:d7bd7384a37c	295	inseg.tcphdr = tcphdr;
grzemich	0:d7bd7384a37c	296
grzemich	0:d7bd7384a37c	297	recv_data = NULL;
grzemich	0:d7bd7384a37c	298	recv_flags = 0;
grzemich	0:d7bd7384a37c	299
grzemich	0:d7bd7384a37c	300	/* If there is data which was previously "refused" by upper layer */
grzemich	0:d7bd7384a37c	301	if (pcb->refused_data != NULL) {
grzemich	0:d7bd7384a37c	302	/* Notify again application with data previously received. */
grzemich	0:d7bd7384a37c	303	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
grzemich	0:d7bd7384a37c	304	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
grzemich	0:d7bd7384a37c	305	if (err == ERR_OK) {
grzemich	0:d7bd7384a37c	306	pcb->refused_data = NULL;
grzemich	0:d7bd7384a37c	307	} else if ((err == ERR_ABRT) \|\| (tcplen > 0)) {
grzemich	0:d7bd7384a37c	308	/* if err == ERR_ABRT, 'pcb' is already deallocated */
grzemich	0:d7bd7384a37c	309	/* Drop incoming packets because pcb is "full" (only if the incoming
grzemich	0:d7bd7384a37c	310	segment contains data). */
grzemich	0:d7bd7384a37c	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
grzemich	0:d7bd7384a37c	312	TCP_STATS_INC(tcp.drop);
grzemich	0:d7bd7384a37c	313	snmp_inc_tcpinerrs();
grzemich	0:d7bd7384a37c	314	pbuf_free(p);
grzemich	0:d7bd7384a37c	315	return;
grzemich	0:d7bd7384a37c	316	}
grzemich	0:d7bd7384a37c	317	}
grzemich	0:d7bd7384a37c	318	tcp_input_pcb = pcb;
grzemich	0:d7bd7384a37c	319	err = tcp_process(pcb);
grzemich	0:d7bd7384a37c	320	/* A return value of ERR_ABRT means that tcp_abort() was called
grzemich	0:d7bd7384a37c	321	and that the pcb has been freed. If so, we don't do anything. */
grzemich	0:d7bd7384a37c	322	if (err != ERR_ABRT) {
grzemich	0:d7bd7384a37c	323	if (recv_flags & TF_RESET) {
grzemich	0:d7bd7384a37c	324	/* TF_RESET means that the connection was reset by the other
grzemich	0:d7bd7384a37c	325	end. We then call the error callback to inform the
grzemich	0:d7bd7384a37c	326	application that the connection is dead before we
grzemich	0:d7bd7384a37c	327	deallocate the PCB. */
grzemich	0:d7bd7384a37c	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
grzemich	0:d7bd7384a37c	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
grzemich	0:d7bd7384a37c	330	memp_free(MEMP_TCP_PCB, pcb);
grzemich	0:d7bd7384a37c	331	} else if (recv_flags & TF_CLOSED) {
grzemich	0:d7bd7384a37c	332	/* The connection has been closed and we will deallocate the
grzemich	0:d7bd7384a37c	333	PCB. */
grzemich	0:d7bd7384a37c	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
grzemich	0:d7bd7384a37c	335	memp_free(MEMP_TCP_PCB, pcb);
grzemich	0:d7bd7384a37c	336	} else {
grzemich	0:d7bd7384a37c	337	err = ERR_OK;
grzemich	0:d7bd7384a37c	338	/* If the application has registered a "sent" function to be
grzemich	0:d7bd7384a37c	339	called when new send buffer space is available, we call it
grzemich	0:d7bd7384a37c	340	now. */
grzemich	0:d7bd7384a37c	341	if (pcb->acked > 0) {
grzemich	0:d7bd7384a37c	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
grzemich	0:d7bd7384a37c	343	if (err == ERR_ABRT) {
grzemich	0:d7bd7384a37c	344	goto aborted;
grzemich	0:d7bd7384a37c	345	}
grzemich	0:d7bd7384a37c	346	}
grzemich	0:d7bd7384a37c	347
grzemich	0:d7bd7384a37c	348	if (recv_data != NULL) {
grzemich	0:d7bd7384a37c	349	LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
grzemich	0:d7bd7384a37c	350	if (pcb->flags & TF_RXCLOSED) {
grzemich	0:d7bd7384a37c	351	/* received data although already closed -> abort (send RST) to
grzemich	0:d7bd7384a37c	352	notify the remote host that not all data has been processed */
grzemich	0:d7bd7384a37c	353	pbuf_free(recv_data);
grzemich	0:d7bd7384a37c	354	tcp_abort(pcb);
grzemich	0:d7bd7384a37c	355	goto aborted;
grzemich	0:d7bd7384a37c	356	}
grzemich	0:d7bd7384a37c	357	if (flags & TCP_PSH) {
grzemich	0:d7bd7384a37c	358	recv_data->flags \|= PBUF_FLAG_PUSH;
grzemich	0:d7bd7384a37c	359	}
grzemich	0:d7bd7384a37c	360
grzemich	0:d7bd7384a37c	361	/* Notify application that data has been received. */
grzemich	0:d7bd7384a37c	362	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
grzemich	0:d7bd7384a37c	363	if (err == ERR_ABRT) {
grzemich	0:d7bd7384a37c	364	goto aborted;
grzemich	0:d7bd7384a37c	365	}
grzemich	0:d7bd7384a37c	366
grzemich	0:d7bd7384a37c	367	/* If the upper layer can't receive this data, store it */
grzemich	0:d7bd7384a37c	368	if (err != ERR_OK) {
grzemich	0:d7bd7384a37c	369	pcb->refused_data = recv_data;
grzemich	0:d7bd7384a37c	370	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
grzemich	0:d7bd7384a37c	371	}
grzemich	0:d7bd7384a37c	372	}
grzemich	0:d7bd7384a37c	373
grzemich	0:d7bd7384a37c	374	/* If a FIN segment was received, we call the callback
grzemich	0:d7bd7384a37c	375	function with a NULL buffer to indicate EOF. */
grzemich	0:d7bd7384a37c	376	if (recv_flags & TF_GOT_FIN) {
grzemich	0:d7bd7384a37c	377	/* correct rcv_wnd as the application won't call tcp_recved()
grzemich	0:d7bd7384a37c	378	for the FIN's seqno */
grzemich	0:d7bd7384a37c	379	if (pcb->rcv_wnd != TCP_WND) {
grzemich	0:d7bd7384a37c	380	pcb->rcv_wnd++;
grzemich	0:d7bd7384a37c	381	}
grzemich	0:d7bd7384a37c	382	TCP_EVENT_CLOSED(pcb, err);
grzemich	0:d7bd7384a37c	383	if (err == ERR_ABRT) {
grzemich	0:d7bd7384a37c	384	goto aborted;
grzemich	0:d7bd7384a37c	385	}
grzemich	0:d7bd7384a37c	386	}
grzemich	0:d7bd7384a37c	387
grzemich	0:d7bd7384a37c	388	tcp_input_pcb = NULL;
grzemich	0:d7bd7384a37c	389	/* Try to send something out. */
grzemich	0:d7bd7384a37c	390	tcp_output(pcb);
grzemich	0:d7bd7384a37c	391	#if TCP_INPUT_DEBUG
grzemich	0:d7bd7384a37c	392	#if TCP_DEBUG
grzemich	0:d7bd7384a37c	393	tcp_debug_print_state(pcb->state);
grzemich	0:d7bd7384a37c	394	#endif /* TCP_DEBUG */
grzemich	0:d7bd7384a37c	395	#endif /* TCP_INPUT_DEBUG */
grzemich	0:d7bd7384a37c	396	}
grzemich	0:d7bd7384a37c	397	}
grzemich	0:d7bd7384a37c	398	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
grzemich	0:d7bd7384a37c	399	Below this line, 'pcb' may not be dereferenced! */
grzemich	0:d7bd7384a37c	400	aborted:
grzemich	0:d7bd7384a37c	401	tcp_input_pcb = NULL;
grzemich	0:d7bd7384a37c	402	recv_data = NULL;
grzemich	0:d7bd7384a37c	403
grzemich	0:d7bd7384a37c	404	/* give up our reference to inseg.p */
grzemich	0:d7bd7384a37c	405	if (inseg.p != NULL)
grzemich	0:d7bd7384a37c	406	{
grzemich	0:d7bd7384a37c	407	pbuf_free(inseg.p);
grzemich	0:d7bd7384a37c	408	inseg.p = NULL;
grzemich	0:d7bd7384a37c	409	}
grzemich	0:d7bd7384a37c	410	} else {
grzemich	0:d7bd7384a37c	411
grzemich	0:d7bd7384a37c	412	/* If no matching PCB was found, send a TCP RST (reset) to the
grzemich	0:d7bd7384a37c	413	sender. */
grzemich	0:d7bd7384a37c	414	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
grzemich	0:d7bd7384a37c	415	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
grzemich	0:d7bd7384a37c	416	TCP_STATS_INC(tcp.proterr);
grzemich	0:d7bd7384a37c	417	TCP_STATS_INC(tcp.drop);
grzemich	0:d7bd7384a37c	418	tcp_rst(ackno, seqno + tcplen,
grzemich	0:d7bd7384a37c	419	ip_current_dest_addr(), ip_current_src_addr(),
grzemich	0:d7bd7384a37c	420	tcphdr->dest, tcphdr->src);
grzemich	0:d7bd7384a37c	421	}
grzemich	0:d7bd7384a37c	422	pbuf_free(p);
grzemich	0:d7bd7384a37c	423	}
grzemich	0:d7bd7384a37c	424
grzemich	0:d7bd7384a37c	425	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
grzemich	0:d7bd7384a37c	426	PERF_STOP("tcp_input");
grzemich	0:d7bd7384a37c	427	}
grzemich	0:d7bd7384a37c	428
grzemich	0:d7bd7384a37c	429	/**
grzemich	0:d7bd7384a37c	430	* Called by tcp_input() when a segment arrives for a listening
grzemich	0:d7bd7384a37c	431	* connection (from tcp_input()).
grzemich	0:d7bd7384a37c	432	*
grzemich	0:d7bd7384a37c	433	* @param pcb the tcp_pcb_listen for which a segment arrived
grzemich	0:d7bd7384a37c	434	* @return ERR_OK if the segment was processed
grzemich	0:d7bd7384a37c	435	* another err_t on error
grzemich	0:d7bd7384a37c	436	*
grzemich	0:d7bd7384a37c	437	* @note the return value is not (yet?) used in tcp_input()
grzemich	0:d7bd7384a37c	438	* @note the segment which arrived is saved in global variables, therefore only the pcb
grzemich	0:d7bd7384a37c	439	* involved is passed as a parameter to this function
grzemich	0:d7bd7384a37c	440	*/
grzemich	0:d7bd7384a37c	441	static err_t
grzemich	0:d7bd7384a37c	442	tcp_listen_input(struct tcp_pcb_listen *pcb)
grzemich	0:d7bd7384a37c	443	{
grzemich	0:d7bd7384a37c	444	struct tcp_pcb *npcb;
grzemich	0:d7bd7384a37c	445	err_t rc;
grzemich	0:d7bd7384a37c	446
grzemich	0:d7bd7384a37c	447	/* In the LISTEN state, we check for incoming SYN segments,
grzemich	0:d7bd7384a37c	448	creates a new PCB, and responds with a SYN\|ACK. */
grzemich	0:d7bd7384a37c	449	if (flags & TCP_ACK) {
grzemich	0:d7bd7384a37c	450	/* For incoming segments with the ACK flag set, respond with a
grzemich	0:d7bd7384a37c	451	RST. */
grzemich	0:d7bd7384a37c	452	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
grzemich	0:d7bd7384a37c	453	tcp_rst(ackno + 1, seqno + tcplen,
grzemich	0:d7bd7384a37c	454	ip_current_dest_addr(), ip_current_src_addr(),
grzemich	0:d7bd7384a37c	455	tcphdr->dest, tcphdr->src);
grzemich	0:d7bd7384a37c	456	} else if (flags & TCP_SYN) {
grzemich	0:d7bd7384a37c	457	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
grzemich	0:d7bd7384a37c	458	#if TCP_LISTEN_BACKLOG
grzemich	0:d7bd7384a37c	459	if (pcb->accepts_pending >= pcb->backlog) {
grzemich	0:d7bd7384a37c	460	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
grzemich	0:d7bd7384a37c	461	return ERR_ABRT;
grzemich	0:d7bd7384a37c	462	}
grzemich	0:d7bd7384a37c	463	#endif /* TCP_LISTEN_BACKLOG */
grzemich	0:d7bd7384a37c	464	npcb = tcp_alloc(pcb->prio);
grzemich	0:d7bd7384a37c	465	/* If a new PCB could not be created (probably due to lack of memory),
grzemich	0:d7bd7384a37c	466	we don't do anything, but rely on the sender will retransmit the
grzemich	0:d7bd7384a37c	467	SYN at a time when we have more memory available. */
grzemich	0:d7bd7384a37c	468	if (npcb == NULL) {
grzemich	0:d7bd7384a37c	469	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
grzemich	0:d7bd7384a37c	470	TCP_STATS_INC(tcp.memerr);
grzemich	0:d7bd7384a37c	471	return ERR_MEM;
grzemich	0:d7bd7384a37c	472	}
grzemich	0:d7bd7384a37c	473	#if TCP_LISTEN_BACKLOG
grzemich	0:d7bd7384a37c	474	pcb->accepts_pending++;
grzemich	0:d7bd7384a37c	475	#endif /* TCP_LISTEN_BACKLOG */
grzemich	0:d7bd7384a37c	476	/* Set up the new PCB. */
grzemich	0:d7bd7384a37c	477	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
grzemich	0:d7bd7384a37c	478	npcb->local_port = pcb->local_port;
grzemich	0:d7bd7384a37c	479	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
grzemich	0:d7bd7384a37c	480	npcb->remote_port = tcphdr->src;
grzemich	0:d7bd7384a37c	481	npcb->state = SYN_RCVD;
grzemich	0:d7bd7384a37c	482	npcb->rcv_nxt = seqno + 1;
grzemich	0:d7bd7384a37c	483	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
grzemich	0:d7bd7384a37c	484	npcb->snd_wnd = tcphdr->wnd;
grzemich	0:d7bd7384a37c	485	npcb->ssthresh = npcb->snd_wnd;
grzemich	0:d7bd7384a37c	486	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
grzemich	0:d7bd7384a37c	487	npcb->callback_arg = pcb->callback_arg;
grzemich	0:d7bd7384a37c	488	#if LWIP_CALLBACK_API
grzemich	0:d7bd7384a37c	489	npcb->accept = pcb->accept;
grzemich	0:d7bd7384a37c	490	#endif /* LWIP_CALLBACK_API */
grzemich	0:d7bd7384a37c	491	/* inherit socket options */
grzemich	0:d7bd7384a37c	492	npcb->so_options = pcb->so_options & SOF_INHERITED;
grzemich	0:d7bd7384a37c	493	/* Register the new PCB so that we can begin receiving segments
grzemich	0:d7bd7384a37c	494	for it. */
grzemich	0:d7bd7384a37c	495	TCP_REG(&tcp_active_pcbs, npcb);
grzemich	0:d7bd7384a37c	496
grzemich	0:d7bd7384a37c	497	/* Parse any options in the SYN. */
grzemich	0:d7bd7384a37c	498	tcp_parseopt(npcb);
grzemich	0:d7bd7384a37c	499	#if TCP_CALCULATE_EFF_SEND_MSS
grzemich	0:d7bd7384a37c	500	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
grzemich	0:d7bd7384a37c	501	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
grzemich	0:d7bd7384a37c	502
grzemich	0:d7bd7384a37c	503	snmp_inc_tcppassiveopens();
grzemich	0:d7bd7384a37c	504
grzemich	0:d7bd7384a37c	505	/* Send a SYN\|ACK together with the MSS option. */
grzemich	0:d7bd7384a37c	506	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
grzemich	0:d7bd7384a37c	507	if (rc != ERR_OK) {
grzemich	0:d7bd7384a37c	508	tcp_abandon(npcb, 0);
grzemich	0:d7bd7384a37c	509	return rc;
grzemich	0:d7bd7384a37c	510	}
grzemich	0:d7bd7384a37c	511	return tcp_output(npcb);
grzemich	0:d7bd7384a37c	512	}
grzemich	0:d7bd7384a37c	513	return ERR_OK;
grzemich	0:d7bd7384a37c	514	}
grzemich	0:d7bd7384a37c	515
grzemich	0:d7bd7384a37c	516	/**
grzemich	0:d7bd7384a37c	517	* Called by tcp_input() when a segment arrives for a connection in
grzemich	0:d7bd7384a37c	518	* TIME_WAIT.
grzemich	0:d7bd7384a37c	519	*
grzemich	0:d7bd7384a37c	520	* @param pcb the tcp_pcb for which a segment arrived
grzemich	0:d7bd7384a37c	521	*
grzemich	0:d7bd7384a37c	522	* @note the segment which arrived is saved in global variables, therefore only the pcb
grzemich	0:d7bd7384a37c	523	* involved is passed as a parameter to this function
grzemich	0:d7bd7384a37c	524	*/
grzemich	0:d7bd7384a37c	525	static err_t
grzemich	0:d7bd7384a37c	526	tcp_timewait_input(struct tcp_pcb *pcb)
grzemich	0:d7bd7384a37c	527	{
grzemich	0:d7bd7384a37c	528	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
grzemich	0:d7bd7384a37c	529	/* RFC 793 3.9 Event Processing - Segment Arrives:
grzemich	0:d7bd7384a37c	530	* - first check sequence number - we skip that one in TIME_WAIT (always
grzemich	0:d7bd7384a37c	531	* acceptable since we only send ACKs)
grzemich	0:d7bd7384a37c	532	* - second check the RST bit (... return) */
grzemich	0:d7bd7384a37c	533	if (flags & TCP_RST) {
grzemich	0:d7bd7384a37c	534	return ERR_OK;
grzemich	0:d7bd7384a37c	535	}
grzemich	0:d7bd7384a37c	536	/* - fourth, check the SYN bit, */
grzemich	0:d7bd7384a37c	537	if (flags & TCP_SYN) {
grzemich	0:d7bd7384a37c	538	/* If an incoming segment is not acceptable, an acknowledgment
grzemich	0:d7bd7384a37c	539	should be sent in reply */
grzemich	0:d7bd7384a37c	540	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
grzemich	0:d7bd7384a37c	541	/* If the SYN is in the window it is an error, send a reset */
grzemich	0:d7bd7384a37c	542	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
grzemich	0:d7bd7384a37c	543	tcphdr->dest, tcphdr->src);
grzemich	0:d7bd7384a37c	544	return ERR_OK;
grzemich	0:d7bd7384a37c	545	}
grzemich	0:d7bd7384a37c	546	} else if (flags & TCP_FIN) {
grzemich	0:d7bd7384a37c	547	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
grzemich	0:d7bd7384a37c	548	Restart the 2 MSL time-wait timeout.*/
grzemich	0:d7bd7384a37c	549	pcb->tmr = tcp_ticks;
grzemich	0:d7bd7384a37c	550	}
grzemich	0:d7bd7384a37c	551
grzemich	0:d7bd7384a37c	552	if ((tcplen > 0)) {
grzemich	0:d7bd7384a37c	553	/* Acknowledge data, FIN or out-of-window SYN */
grzemich	0:d7bd7384a37c	554	pcb->flags \|= TF_ACK_NOW;
grzemich	0:d7bd7384a37c	555	return tcp_output(pcb);
grzemich	0:d7bd7384a37c	556	}
grzemich	0:d7bd7384a37c	557	return ERR_OK;
grzemich	0:d7bd7384a37c	558	}
grzemich	0:d7bd7384a37c	559
grzemich	0:d7bd7384a37c	560	/**
grzemich	0:d7bd7384a37c	561	* Implements the TCP state machine. Called by tcp_input. In some
grzemich	0:d7bd7384a37c	562	* states tcp_receive() is called to receive data. The tcp_seg
grzemich	0:d7bd7384a37c	563	* argument will be freed by the caller (tcp_input()) unless the
grzemich	0:d7bd7384a37c	564	* recv_data pointer in the pcb is set.
grzemich	0:d7bd7384a37c	565	*
grzemich	0:d7bd7384a37c	566	* @param pcb the tcp_pcb for which a segment arrived
grzemich	0:d7bd7384a37c	567	*
grzemich	0:d7bd7384a37c	568	* @note the segment which arrived is saved in global variables, therefore only the pcb
grzemich	0:d7bd7384a37c	569	* involved is passed as a parameter to this function
grzemich	0:d7bd7384a37c	570	*/
grzemich	0:d7bd7384a37c	571	static err_t
grzemich	0:d7bd7384a37c	572	tcp_process(struct tcp_pcb *pcb)
grzemich	0:d7bd7384a37c	573	{
grzemich	0:d7bd7384a37c	574	struct tcp_seg *rseg;
grzemich	0:d7bd7384a37c	575	u8_t acceptable = 0;
grzemich	0:d7bd7384a37c	576	err_t err;
grzemich	0:d7bd7384a37c	577
grzemich	0:d7bd7384a37c	578	err = ERR_OK;
grzemich	0:d7bd7384a37c	579
grzemich	0:d7bd7384a37c	580	/* Process incoming RST segments. */
grzemich	0:d7bd7384a37c	581	if (flags & TCP_RST) {
grzemich	0:d7bd7384a37c	582	/* First, determine if the reset is acceptable. */
grzemich	0:d7bd7384a37c	583	if (pcb->state == SYN_SENT) {
grzemich	0:d7bd7384a37c	584	if (ackno == pcb->snd_nxt) {
grzemich	0:d7bd7384a37c	585	acceptable = 1;
grzemich	0:d7bd7384a37c	586	}
grzemich	0:d7bd7384a37c	587	} else {
grzemich	0:d7bd7384a37c	588	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
grzemich	0:d7bd7384a37c	589	pcb->rcv_nxt+pcb->rcv_wnd)) {
grzemich	0:d7bd7384a37c	590	acceptable = 1;
grzemich	0:d7bd7384a37c	591	}
grzemich	0:d7bd7384a37c	592	}
grzemich	0:d7bd7384a37c	593
grzemich	0:d7bd7384a37c	594	if (acceptable) {
grzemich	0:d7bd7384a37c	595	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
grzemich	0:d7bd7384a37c	596	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
grzemich	0:d7bd7384a37c	597	recv_flags \|= TF_RESET;
grzemich	0:d7bd7384a37c	598	pcb->flags &= ~TF_ACK_DELAY;
grzemich	0:d7bd7384a37c	599	return ERR_RST;
grzemich	0:d7bd7384a37c	600	} else {
grzemich	0:d7bd7384a37c	601	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
grzemich	0:d7bd7384a37c	602	seqno, pcb->rcv_nxt));
grzemich	0:d7bd7384a37c	603	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
grzemich	0:d7bd7384a37c	604	seqno, pcb->rcv_nxt));
grzemich	0:d7bd7384a37c	605	return ERR_OK;
grzemich	0:d7bd7384a37c	606	}
grzemich	0:d7bd7384a37c	607	}
grzemich	0:d7bd7384a37c	608
grzemich	0:d7bd7384a37c	609	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
grzemich	0:d7bd7384a37c	610	/* Cope with new connection attempt after remote end crashed */
grzemich	0:d7bd7384a37c	611	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	612	return ERR_OK;
grzemich	0:d7bd7384a37c	613	}
grzemich	0:d7bd7384a37c	614
grzemich	0:d7bd7384a37c	615	if ((pcb->flags & TF_RXCLOSED) == 0) {
grzemich	0:d7bd7384a37c	616	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
grzemich	0:d7bd7384a37c	617	pcb->tmr = tcp_ticks;
grzemich	0:d7bd7384a37c	618	}
grzemich	0:d7bd7384a37c	619	pcb->keep_cnt_sent = 0;
grzemich	0:d7bd7384a37c	620
grzemich	0:d7bd7384a37c	621	tcp_parseopt(pcb);
grzemich	0:d7bd7384a37c	622
grzemich	0:d7bd7384a37c	623	/* Do different things depending on the TCP state. */
grzemich	0:d7bd7384a37c	624	switch (pcb->state) {
grzemich	0:d7bd7384a37c	625	case SYN_SENT:
grzemich	0:d7bd7384a37c	626	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
grzemich	0:d7bd7384a37c	627	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
grzemich	0:d7bd7384a37c	628	/* received SYN ACK with expected sequence number? */
grzemich	0:d7bd7384a37c	629	if ((flags & TCP_ACK) && (flags & TCP_SYN)
grzemich	0:d7bd7384a37c	630	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
grzemich	0:d7bd7384a37c	631	pcb->snd_buf++;
grzemich	0:d7bd7384a37c	632	pcb->rcv_nxt = seqno + 1;
grzemich	0:d7bd7384a37c	633	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
grzemich	0:d7bd7384a37c	634	pcb->lastack = ackno;
grzemich	0:d7bd7384a37c	635	pcb->snd_wnd = tcphdr->wnd;
grzemich	0:d7bd7384a37c	636	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
grzemich	0:d7bd7384a37c	637	pcb->state = ESTABLISHED;
grzemich	0:d7bd7384a37c	638
grzemich	0:d7bd7384a37c	639	#if TCP_CALCULATE_EFF_SEND_MSS
grzemich	0:d7bd7384a37c	640	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
grzemich	0:d7bd7384a37c	641	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
grzemich	0:d7bd7384a37c	642
grzemich	0:d7bd7384a37c	643	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
grzemich	0:d7bd7384a37c	644	* but for the default value of pcb->mss) */
grzemich	0:d7bd7384a37c	645	pcb->ssthresh = pcb->mss * 10;
grzemich	0:d7bd7384a37c	646
grzemich	0:d7bd7384a37c	647	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
grzemich	0:d7bd7384a37c	648	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
grzemich	0:d7bd7384a37c	649	--pcb->snd_queuelen;
grzemich	0:d7bd7384a37c	650	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
grzemich	0:d7bd7384a37c	651	rseg = pcb->unacked;
grzemich	0:d7bd7384a37c	652	pcb->unacked = rseg->next;
grzemich	0:d7bd7384a37c	653
grzemich	0:d7bd7384a37c	654	/* If there's nothing left to acknowledge, stop the retransmit
grzemich	0:d7bd7384a37c	655	timer, otherwise reset it to start again */
grzemich	0:d7bd7384a37c	656	if(pcb->unacked == NULL)
grzemich	0:d7bd7384a37c	657	pcb->rtime = -1;
grzemich	0:d7bd7384a37c	658	else {
grzemich	0:d7bd7384a37c	659	pcb->rtime = 0;
grzemich	0:d7bd7384a37c	660	pcb->nrtx = 0;
grzemich	0:d7bd7384a37c	661	}
grzemich	0:d7bd7384a37c	662
grzemich	0:d7bd7384a37c	663	tcp_seg_free(rseg);
grzemich	0:d7bd7384a37c	664
grzemich	0:d7bd7384a37c	665	/* Call the user specified function to call when sucessfully
grzemich	0:d7bd7384a37c	666	* connected. */
grzemich	0:d7bd7384a37c	667	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
grzemich	0:d7bd7384a37c	668	if (err == ERR_ABRT) {
grzemich	0:d7bd7384a37c	669	return ERR_ABRT;
grzemich	0:d7bd7384a37c	670	}
grzemich	0:d7bd7384a37c	671	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	672	}
grzemich	0:d7bd7384a37c	673	/* received ACK? possibly a half-open connection */
grzemich	0:d7bd7384a37c	674	else if (flags & TCP_ACK) {
grzemich	0:d7bd7384a37c	675	/* send a RST to bring the other side in a non-synchronized state. */
grzemich	0:d7bd7384a37c	676	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
grzemich	0:d7bd7384a37c	677	tcphdr->dest, tcphdr->src);
grzemich	0:d7bd7384a37c	678	}
grzemich	0:d7bd7384a37c	679	break;
grzemich	0:d7bd7384a37c	680	case SYN_RCVD:
grzemich	0:d7bd7384a37c	681	if (flags & TCP_ACK) {
grzemich	0:d7bd7384a37c	682	/* expected ACK number? */
grzemich	0:d7bd7384a37c	683	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
grzemich	0:d7bd7384a37c	684	u16_t old_cwnd;
grzemich	0:d7bd7384a37c	685	pcb->state = ESTABLISHED;
grzemich	0:d7bd7384a37c	686	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
grzemich	0:d7bd7384a37c	687	#if LWIP_CALLBACK_API
grzemich	0:d7bd7384a37c	688	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
grzemich	0:d7bd7384a37c	689	#endif
grzemich	0:d7bd7384a37c	690	/* Call the accept function. */
grzemich	0:d7bd7384a37c	691	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
grzemich	0:d7bd7384a37c	692	if (err != ERR_OK) {
grzemich	0:d7bd7384a37c	693	/* If the accept function returns with an error, we abort
grzemich	0:d7bd7384a37c	694	* the connection. */
grzemich	0:d7bd7384a37c	695	/* Already aborted? */
grzemich	0:d7bd7384a37c	696	if (err != ERR_ABRT) {
grzemich	0:d7bd7384a37c	697	tcp_abort(pcb);
grzemich	0:d7bd7384a37c	698	}
grzemich	0:d7bd7384a37c	699	return ERR_ABRT;
grzemich	0:d7bd7384a37c	700	}
grzemich	0:d7bd7384a37c	701	old_cwnd = pcb->cwnd;
grzemich	0:d7bd7384a37c	702	/* If there was any data contained within this ACK,
grzemich	0:d7bd7384a37c	703	* we'd better pass it on to the application as well. */
grzemich	0:d7bd7384a37c	704	tcp_receive(pcb);
grzemich	0:d7bd7384a37c	705
grzemich	0:d7bd7384a37c	706	/* Prevent ACK for SYN to generate a sent event */
grzemich	0:d7bd7384a37c	707	if (pcb->acked != 0) {
grzemich	0:d7bd7384a37c	708	pcb->acked--;
grzemich	0:d7bd7384a37c	709	}
grzemich	0:d7bd7384a37c	710
grzemich	0:d7bd7384a37c	711	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
grzemich	0:d7bd7384a37c	712
grzemich	0:d7bd7384a37c	713	if (recv_flags & TF_GOT_FIN) {
grzemich	0:d7bd7384a37c	714	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	715	pcb->state = CLOSE_WAIT;
grzemich	0:d7bd7384a37c	716	}
grzemich	0:d7bd7384a37c	717	} else {
grzemich	0:d7bd7384a37c	718	/* incorrect ACK number, send RST */
grzemich	0:d7bd7384a37c	719	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
grzemich	0:d7bd7384a37c	720	tcphdr->dest, tcphdr->src);
grzemich	0:d7bd7384a37c	721	}
grzemich	0:d7bd7384a37c	722	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
grzemich	0:d7bd7384a37c	723	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
grzemich	0:d7bd7384a37c	724	tcp_rexmit(pcb);
grzemich	0:d7bd7384a37c	725	}
grzemich	0:d7bd7384a37c	726	break;
grzemich	0:d7bd7384a37c	727	case CLOSE_WAIT:
grzemich	0:d7bd7384a37c	728	/* FALLTHROUGH */
grzemich	0:d7bd7384a37c	729	case ESTABLISHED:
grzemich	0:d7bd7384a37c	730	tcp_receive(pcb);
grzemich	0:d7bd7384a37c	731	if (recv_flags & TF_GOT_FIN) { /* passive close */
grzemich	0:d7bd7384a37c	732	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	733	pcb->state = CLOSE_WAIT;
grzemich	0:d7bd7384a37c	734	}
grzemich	0:d7bd7384a37c	735	break;
grzemich	0:d7bd7384a37c	736	case FIN_WAIT_1:
grzemich	0:d7bd7384a37c	737	tcp_receive(pcb);
grzemich	0:d7bd7384a37c	738	if (recv_flags & TF_GOT_FIN) {
grzemich	0:d7bd7384a37c	739	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
grzemich	0:d7bd7384a37c	740	LWIP_DEBUGF(TCP_DEBUG,
grzemich	0:d7bd7384a37c	741	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
grzemich	0:d7bd7384a37c	742	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	743	tcp_pcb_purge(pcb);
grzemich	0:d7bd7384a37c	744	TCP_RMV(&tcp_active_pcbs, pcb);
grzemich	0:d7bd7384a37c	745	pcb->state = TIME_WAIT;
grzemich	0:d7bd7384a37c	746	TCP_REG(&tcp_tw_pcbs, pcb);
grzemich	0:d7bd7384a37c	747	} else {
grzemich	0:d7bd7384a37c	748	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	749	pcb->state = CLOSING;
grzemich	0:d7bd7384a37c	750	}
grzemich	0:d7bd7384a37c	751	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
grzemich	0:d7bd7384a37c	752	pcb->state = FIN_WAIT_2;
grzemich	0:d7bd7384a37c	753	}
grzemich	0:d7bd7384a37c	754	break;
grzemich	0:d7bd7384a37c	755	case FIN_WAIT_2:
grzemich	0:d7bd7384a37c	756	tcp_receive(pcb);
grzemich	0:d7bd7384a37c	757	if (recv_flags & TF_GOT_FIN) {
grzemich	0:d7bd7384a37c	758	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
grzemich	0:d7bd7384a37c	759	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	760	tcp_pcb_purge(pcb);
grzemich	0:d7bd7384a37c	761	TCP_RMV(&tcp_active_pcbs, pcb);
grzemich	0:d7bd7384a37c	762	pcb->state = TIME_WAIT;
grzemich	0:d7bd7384a37c	763	TCP_REG(&tcp_tw_pcbs, pcb);
grzemich	0:d7bd7384a37c	764	}
grzemich	0:d7bd7384a37c	765	break;
grzemich	0:d7bd7384a37c	766	case CLOSING:
grzemich	0:d7bd7384a37c	767	tcp_receive(pcb);
grzemich	0:d7bd7384a37c	768	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
grzemich	0:d7bd7384a37c	769	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
grzemich	0:d7bd7384a37c	770	tcp_pcb_purge(pcb);
grzemich	0:d7bd7384a37c	771	TCP_RMV(&tcp_active_pcbs, pcb);
grzemich	0:d7bd7384a37c	772	pcb->state = TIME_WAIT;
grzemich	0:d7bd7384a37c	773	TCP_REG(&tcp_tw_pcbs, pcb);
grzemich	0:d7bd7384a37c	774	}
grzemich	0:d7bd7384a37c	775	break;
grzemich	0:d7bd7384a37c	776	case LAST_ACK:
grzemich	0:d7bd7384a37c	777	tcp_receive(pcb);
grzemich	0:d7bd7384a37c	778	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
grzemich	0:d7bd7384a37c	779	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
grzemich	0:d7bd7384a37c	780	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
grzemich	0:d7bd7384a37c	781	recv_flags \|= TF_CLOSED;
grzemich	0:d7bd7384a37c	782	}
grzemich	0:d7bd7384a37c	783	break;
grzemich	0:d7bd7384a37c	784	default:
grzemich	0:d7bd7384a37c	785	break;
grzemich	0:d7bd7384a37c	786	}
grzemich	0:d7bd7384a37c	787	return ERR_OK;
grzemich	0:d7bd7384a37c	788	}
grzemich	0:d7bd7384a37c	789
grzemich	0:d7bd7384a37c	790	#if TCP_QUEUE_OOSEQ
grzemich	0:d7bd7384a37c	791	/**
grzemich	0:d7bd7384a37c	792	* Insert segment into the list (segments covered with new one will be deleted)
grzemich	0:d7bd7384a37c	793	*
grzemich	0:d7bd7384a37c	794	* Called from tcp_receive()
grzemich	0:d7bd7384a37c	795	*/
grzemich	0:d7bd7384a37c	796	static void
grzemich	0:d7bd7384a37c	797	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
grzemich	0:d7bd7384a37c	798	{
grzemich	0:d7bd7384a37c	799	struct tcp_seg *old_seg;
grzemich	0:d7bd7384a37c	800
grzemich	0:d7bd7384a37c	801	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	802	/* received segment overlaps all following segments */
grzemich	0:d7bd7384a37c	803	tcp_segs_free(next);
grzemich	0:d7bd7384a37c	804	next = NULL;
grzemich	0:d7bd7384a37c	805	}
grzemich	0:d7bd7384a37c	806	else {
grzemich	0:d7bd7384a37c	807	/* delete some following segments
grzemich	0:d7bd7384a37c	808	oos queue may have segments with FIN flag */
grzemich	0:d7bd7384a37c	809	while (next &&
grzemich	0:d7bd7384a37c	810	TCP_SEQ_GEQ((seqno + cseg->len),
grzemich	0:d7bd7384a37c	811	(next->tcphdr->seqno + next->len))) {
grzemich	0:d7bd7384a37c	812	/* cseg with FIN already processed */
grzemich	0:d7bd7384a37c	813	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	814	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
grzemich	0:d7bd7384a37c	815	}
grzemich	0:d7bd7384a37c	816	old_seg = next;
grzemich	0:d7bd7384a37c	817	next = next->next;
grzemich	0:d7bd7384a37c	818	tcp_seg_free(old_seg);
grzemich	0:d7bd7384a37c	819	}
grzemich	0:d7bd7384a37c	820	if (next &&
grzemich	0:d7bd7384a37c	821	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
grzemich	0:d7bd7384a37c	822	/* We need to trim the incoming segment. */
grzemich	0:d7bd7384a37c	823	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
grzemich	0:d7bd7384a37c	824	pbuf_realloc(cseg->p, cseg->len);
grzemich	0:d7bd7384a37c	825	}
grzemich	0:d7bd7384a37c	826	}
grzemich	0:d7bd7384a37c	827	cseg->next = next;
grzemich	0:d7bd7384a37c	828	}
grzemich	0:d7bd7384a37c	829	#endif /* TCP_QUEUE_OOSEQ */
grzemich	0:d7bd7384a37c	830
grzemich	0:d7bd7384a37c	831	/**
grzemich	0:d7bd7384a37c	832	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
grzemich	0:d7bd7384a37c	833	* data, and if so frees the memory of the buffered data. Next, is places the
grzemich	0:d7bd7384a37c	834	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
grzemich	0:d7bd7384a37c	835	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
grzemich	0:d7bd7384a37c	836	* i it has been removed from the buffer.
grzemich	0:d7bd7384a37c	837	*
grzemich	0:d7bd7384a37c	838	* If the incoming segment constitutes an ACK for a segment that was used for RTT
grzemich	0:d7bd7384a37c	839	* estimation, the RTT is estimated here as well.
grzemich	0:d7bd7384a37c	840	*
grzemich	0:d7bd7384a37c	841	* Called from tcp_process().
grzemich	0:d7bd7384a37c	842	*/
grzemich	0:d7bd7384a37c	843	static void
grzemich	0:d7bd7384a37c	844	tcp_receive(struct tcp_pcb *pcb)
grzemich	0:d7bd7384a37c	845	{
grzemich	0:d7bd7384a37c	846	struct tcp_seg *next;
grzemich	0:d7bd7384a37c	847	#if TCP_QUEUE_OOSEQ
grzemich	0:d7bd7384a37c	848	struct tcp_seg prev, cseg;
grzemich	0:d7bd7384a37c	849	#endif /* TCP_QUEUE_OOSEQ */
grzemich	0:d7bd7384a37c	850	struct pbuf *p;
grzemich	0:d7bd7384a37c	851	s32_t off;
grzemich	0:d7bd7384a37c	852	s16_t m;
grzemich	0:d7bd7384a37c	853	u32_t right_wnd_edge;
grzemich	0:d7bd7384a37c	854	u16_t new_tot_len;
grzemich	0:d7bd7384a37c	855	int found_dupack = 0;
grzemich	0:d7bd7384a37c	856
grzemich	0:d7bd7384a37c	857	if (flags & TCP_ACK) {
grzemich	0:d7bd7384a37c	858	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
grzemich	0:d7bd7384a37c	859
grzemich	0:d7bd7384a37c	860	/* Update window. */
grzemich	0:d7bd7384a37c	861	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
grzemich	0:d7bd7384a37c	862	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
grzemich	0:d7bd7384a37c	863	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
grzemich	0:d7bd7384a37c	864	pcb->snd_wnd = tcphdr->wnd;
grzemich	0:d7bd7384a37c	865	pcb->snd_wl1 = seqno;
grzemich	0:d7bd7384a37c	866	pcb->snd_wl2 = ackno;
grzemich	0:d7bd7384a37c	867	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
grzemich	0:d7bd7384a37c	868	pcb->persist_backoff = 0;
grzemich	0:d7bd7384a37c	869	}
grzemich	0:d7bd7384a37c	870	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
grzemich	0:d7bd7384a37c	871	#if TCP_WND_DEBUG
grzemich	0:d7bd7384a37c	872	} else {
grzemich	0:d7bd7384a37c	873	if (pcb->snd_wnd != tcphdr->wnd) {
grzemich	0:d7bd7384a37c	874	LWIP_DEBUGF(TCP_WND_DEBUG,
grzemich	0:d7bd7384a37c	875	("tcp_receive: no window update lastack %"U32_F" ackno %"
grzemich	0:d7bd7384a37c	876	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
grzemich	0:d7bd7384a37c	877	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
grzemich	0:d7bd7384a37c	878	}
grzemich	0:d7bd7384a37c	879	#endif /* TCP_WND_DEBUG */
grzemich	0:d7bd7384a37c	880	}
grzemich	0:d7bd7384a37c	881
grzemich	0:d7bd7384a37c	882	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
grzemich	0:d7bd7384a37c	883	* duplicate ack if:
grzemich	0:d7bd7384a37c	884	* 1) It doesn't ACK new data
grzemich	0:d7bd7384a37c	885	* 2) length of received packet is zero (i.e. no payload)
grzemich	0:d7bd7384a37c	886	* 3) the advertised window hasn't changed
grzemich	0:d7bd7384a37c	887	* 4) There is outstanding unacknowledged data (retransmission timer running)
grzemich	0:d7bd7384a37c	888	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
grzemich	0:d7bd7384a37c	889	*
grzemich	0:d7bd7384a37c	890	* If it passes all five, should process as a dupack:
grzemich	0:d7bd7384a37c	891	* a) dupacks < 3: do nothing
grzemich	0:d7bd7384a37c	892	* b) dupacks == 3: fast retransmit
grzemich	0:d7bd7384a37c	893	* c) dupacks > 3: increase cwnd
grzemich	0:d7bd7384a37c	894	*
grzemich	0:d7bd7384a37c	895	* If it only passes 1-3, should reset dupack counter (and add to
grzemich	0:d7bd7384a37c	896	* stats, which we don't do in lwIP)
grzemich	0:d7bd7384a37c	897	*
grzemich	0:d7bd7384a37c	898	* If it only passes 1, should reset dupack counter
grzemich	0:d7bd7384a37c	899	*
grzemich	0:d7bd7384a37c	900	*/
grzemich	0:d7bd7384a37c	901
grzemich	0:d7bd7384a37c	902	/* Clause 1 */
grzemich	0:d7bd7384a37c	903	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
grzemich	0:d7bd7384a37c	904	pcb->acked = 0;
grzemich	0:d7bd7384a37c	905	/* Clause 2 */
grzemich	0:d7bd7384a37c	906	if (tcplen == 0) {
grzemich	0:d7bd7384a37c	907	/* Clause 3 */
grzemich	0:d7bd7384a37c	908	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
grzemich	0:d7bd7384a37c	909	/* Clause 4 */
grzemich	0:d7bd7384a37c	910	if (pcb->rtime >= 0) {
grzemich	0:d7bd7384a37c	911	/* Clause 5 */
grzemich	0:d7bd7384a37c	912	if (pcb->lastack == ackno) {
grzemich	0:d7bd7384a37c	913	found_dupack = 1;
grzemich	0:d7bd7384a37c	914	if (pcb->dupacks + 1 > pcb->dupacks)
grzemich	0:d7bd7384a37c	915	++pcb->dupacks;
grzemich	0:d7bd7384a37c	916	if (pcb->dupacks > 3) {
grzemich	0:d7bd7384a37c	917	/* Inflate the congestion window, but not if it means that
grzemich	0:d7bd7384a37c	918	the value overflows. */
grzemich	0:d7bd7384a37c	919	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
grzemich	0:d7bd7384a37c	920	pcb->cwnd += pcb->mss;
grzemich	0:d7bd7384a37c	921	}
grzemich	0:d7bd7384a37c	922	} else if (pcb->dupacks == 3) {
grzemich	0:d7bd7384a37c	923	/* Do fast retransmit */
grzemich	0:d7bd7384a37c	924	tcp_rexmit_fast(pcb);
grzemich	0:d7bd7384a37c	925	}
grzemich	0:d7bd7384a37c	926	}
grzemich	0:d7bd7384a37c	927	}
grzemich	0:d7bd7384a37c	928	}
grzemich	0:d7bd7384a37c	929	}
grzemich	0:d7bd7384a37c	930	/* If Clause (1) or more is true, but not a duplicate ack, reset
grzemich	0:d7bd7384a37c	931	* count of consecutive duplicate acks */
grzemich	0:d7bd7384a37c	932	if (!found_dupack) {
grzemich	0:d7bd7384a37c	933	pcb->dupacks = 0;
grzemich	0:d7bd7384a37c	934	}
grzemich	0:d7bd7384a37c	935	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
grzemich	0:d7bd7384a37c	936	/* We come here when the ACK acknowledges new data. */
grzemich	0:d7bd7384a37c	937
grzemich	0:d7bd7384a37c	938	/* Reset the "IN Fast Retransmit" flag, since we are no longer
grzemich	0:d7bd7384a37c	939	in fast retransmit. Also reset the congestion window to the
grzemich	0:d7bd7384a37c	940	slow start threshold. */
grzemich	0:d7bd7384a37c	941	if (pcb->flags & TF_INFR) {
grzemich	0:d7bd7384a37c	942	pcb->flags &= ~TF_INFR;
grzemich	0:d7bd7384a37c	943	pcb->cwnd = pcb->ssthresh;
grzemich	0:d7bd7384a37c	944	}
grzemich	0:d7bd7384a37c	945
grzemich	0:d7bd7384a37c	946	/* Reset the number of retransmissions. */
grzemich	0:d7bd7384a37c	947	pcb->nrtx = 0;
grzemich	0:d7bd7384a37c	948
grzemich	0:d7bd7384a37c	949	/* Reset the retransmission time-out. */
grzemich	0:d7bd7384a37c	950	pcb->rto = (pcb->sa >> 3) + pcb->sv;
grzemich	0:d7bd7384a37c	951
grzemich	0:d7bd7384a37c	952	/* Update the send buffer space. Diff between the two can never exceed 64K? */
grzemich	0:d7bd7384a37c	953	pcb->acked = (u16_t)(ackno - pcb->lastack);
grzemich	0:d7bd7384a37c	954
grzemich	0:d7bd7384a37c	955	pcb->snd_buf += pcb->acked;
grzemich	0:d7bd7384a37c	956
grzemich	0:d7bd7384a37c	957	/* Reset the fast retransmit variables. */
grzemich	0:d7bd7384a37c	958	pcb->dupacks = 0;
grzemich	0:d7bd7384a37c	959	pcb->lastack = ackno;
grzemich	0:d7bd7384a37c	960
grzemich	0:d7bd7384a37c	961	/* Update the congestion control variables (cwnd and
grzemich	0:d7bd7384a37c	962	ssthresh). */
grzemich	0:d7bd7384a37c	963	if (pcb->state >= ESTABLISHED) {
grzemich	0:d7bd7384a37c	964	if (pcb->cwnd < pcb->ssthresh) {
grzemich	0:d7bd7384a37c	965	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
grzemich	0:d7bd7384a37c	966	pcb->cwnd += pcb->mss;
grzemich	0:d7bd7384a37c	967	}
grzemich	0:d7bd7384a37c	968	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
grzemich	0:d7bd7384a37c	969	} else {
grzemich	0:d7bd7384a37c	970	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
grzemich	0:d7bd7384a37c	971	if (new_cwnd > pcb->cwnd) {
grzemich	0:d7bd7384a37c	972	pcb->cwnd = new_cwnd;
grzemich	0:d7bd7384a37c	973	}
grzemich	0:d7bd7384a37c	974	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
grzemich	0:d7bd7384a37c	975	}
grzemich	0:d7bd7384a37c	976	}
grzemich	0:d7bd7384a37c	977	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
grzemich	0:d7bd7384a37c	978	ackno,
grzemich	0:d7bd7384a37c	979	pcb->unacked != NULL?
grzemich	0:d7bd7384a37c	980	ntohl(pcb->unacked->tcphdr->seqno): 0,
grzemich	0:d7bd7384a37c	981	pcb->unacked != NULL?
grzemich	0:d7bd7384a37c	982	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
grzemich	0:d7bd7384a37c	983
grzemich	0:d7bd7384a37c	984	/* Remove segment from the unacknowledged list if the incoming
grzemich	0:d7bd7384a37c	985	ACK acknowlegdes them. */
grzemich	0:d7bd7384a37c	986	while (pcb->unacked != NULL &&
grzemich	0:d7bd7384a37c	987	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
grzemich	0:d7bd7384a37c	988	TCP_TCPLEN(pcb->unacked), ackno)) {
grzemich	0:d7bd7384a37c	989	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
grzemich	0:d7bd7384a37c	990	ntohl(pcb->unacked->tcphdr->seqno),
grzemich	0:d7bd7384a37c	991	ntohl(pcb->unacked->tcphdr->seqno) +
grzemich	0:d7bd7384a37c	992	TCP_TCPLEN(pcb->unacked)));
grzemich	0:d7bd7384a37c	993
grzemich	0:d7bd7384a37c	994	next = pcb->unacked;
grzemich	0:d7bd7384a37c	995	pcb->unacked = pcb->unacked->next;
grzemich	0:d7bd7384a37c	996
grzemich	0:d7bd7384a37c	997	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
grzemich	0:d7bd7384a37c	998	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
grzemich	0:d7bd7384a37c	999	/* Prevent ACK for FIN to generate a sent event */
grzemich	0:d7bd7384a37c	1000	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
grzemich	0:d7bd7384a37c	1001	pcb->acked--;
grzemich	0:d7bd7384a37c	1002	}
grzemich	0:d7bd7384a37c	1003
grzemich	0:d7bd7384a37c	1004	pcb->snd_queuelen -= pbuf_clen(next->p);
grzemich	0:d7bd7384a37c	1005	tcp_seg_free(next);
grzemich	0:d7bd7384a37c	1006
grzemich	0:d7bd7384a37c	1007	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
grzemich	0:d7bd7384a37c	1008	if (pcb->snd_queuelen != 0) {
grzemich	0:d7bd7384a37c	1009	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
grzemich	0:d7bd7384a37c	1010	pcb->unsent != NULL);
grzemich	0:d7bd7384a37c	1011	}
grzemich	0:d7bd7384a37c	1012	}
grzemich	0:d7bd7384a37c	1013
grzemich	0:d7bd7384a37c	1014	/* If there's nothing left to acknowledge, stop the retransmit
grzemich	0:d7bd7384a37c	1015	timer, otherwise reset it to start again */
grzemich	0:d7bd7384a37c	1016	if(pcb->unacked == NULL)
grzemich	0:d7bd7384a37c	1017	pcb->rtime = -1;
grzemich	0:d7bd7384a37c	1018	else
grzemich	0:d7bd7384a37c	1019	pcb->rtime = 0;
grzemich	0:d7bd7384a37c	1020
grzemich	0:d7bd7384a37c	1021	pcb->polltmr = 0;
grzemich	0:d7bd7384a37c	1022	} else {
grzemich	0:d7bd7384a37c	1023	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
grzemich	0:d7bd7384a37c	1024	pcb->acked = 0;
grzemich	0:d7bd7384a37c	1025	}
grzemich	0:d7bd7384a37c	1026
grzemich	0:d7bd7384a37c	1027	/* We go through the ->unsent list to see if any of the segments
grzemich	0:d7bd7384a37c	1028	on the list are acknowledged by the ACK. This may seem
grzemich	0:d7bd7384a37c	1029	strange since an "unsent" segment shouldn't be acked. The
grzemich	0:d7bd7384a37c	1030	rationale is that lwIP puts all outstanding segments on the
grzemich	0:d7bd7384a37c	1031	->unsent list after a retransmission, so these segments may
grzemich	0:d7bd7384a37c	1032	in fact have been sent once. */
grzemich	0:d7bd7384a37c	1033	while (pcb->unsent != NULL &&
grzemich	0:d7bd7384a37c	1034	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
grzemich	0:d7bd7384a37c	1035	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
grzemich	0:d7bd7384a37c	1036	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
grzemich	0:d7bd7384a37c	1037	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
grzemich	0:d7bd7384a37c	1038	TCP_TCPLEN(pcb->unsent)));
grzemich	0:d7bd7384a37c	1039
grzemich	0:d7bd7384a37c	1040	next = pcb->unsent;
grzemich	0:d7bd7384a37c	1041	pcb->unsent = pcb->unsent->next;
grzemich	0:d7bd7384a37c	1042	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
grzemich	0:d7bd7384a37c	1043	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
grzemich	0:d7bd7384a37c	1044	/* Prevent ACK for FIN to generate a sent event */
grzemich	0:d7bd7384a37c	1045	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
grzemich	0:d7bd7384a37c	1046	pcb->acked--;
grzemich	0:d7bd7384a37c	1047	}
grzemich	0:d7bd7384a37c	1048	pcb->snd_queuelen -= pbuf_clen(next->p);
grzemich	0:d7bd7384a37c	1049	tcp_seg_free(next);
grzemich	0:d7bd7384a37c	1050	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
grzemich	0:d7bd7384a37c	1051	if (pcb->snd_queuelen != 0) {
grzemich	0:d7bd7384a37c	1052	LWIP_ASSERT("tcp_receive: valid queue length",
grzemich	0:d7bd7384a37c	1053	pcb->unacked != NULL \|\| pcb->unsent != NULL);
grzemich	0:d7bd7384a37c	1054	}
grzemich	0:d7bd7384a37c	1055	}
grzemich	0:d7bd7384a37c	1056	/* End of ACK for new data processing. */
grzemich	0:d7bd7384a37c	1057
grzemich	0:d7bd7384a37c	1058	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
grzemich	0:d7bd7384a37c	1059	pcb->rttest, pcb->rtseq, ackno));
grzemich	0:d7bd7384a37c	1060
grzemich	0:d7bd7384a37c	1061	/* RTT estimation calculations. This is done by checking if the
grzemich	0:d7bd7384a37c	1062	incoming segment acknowledges the segment we use to take a
grzemich	0:d7bd7384a37c	1063	round-trip time measurement. */
grzemich	0:d7bd7384a37c	1064	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
grzemich	0:d7bd7384a37c	1065	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
grzemich	0:d7bd7384a37c	1066	and a round-trip shouldn't be that long... */
grzemich	0:d7bd7384a37c	1067	m = (s16_t)(tcp_ticks - pcb->rttest);
grzemich	0:d7bd7384a37c	1068
grzemich	0:d7bd7384a37c	1069	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
grzemich	0:d7bd7384a37c	1070	m, m * TCP_SLOW_INTERVAL));
grzemich	0:d7bd7384a37c	1071
grzemich	0:d7bd7384a37c	1072	/* This is taken directly from VJs original code in his paper */
grzemich	0:d7bd7384a37c	1073	m = m - (pcb->sa >> 3);
grzemich	0:d7bd7384a37c	1074	pcb->sa += m;
grzemich	0:d7bd7384a37c	1075	if (m < 0) {
grzemich	0:d7bd7384a37c	1076	m = -m;
grzemich	0:d7bd7384a37c	1077	}
grzemich	0:d7bd7384a37c	1078	m = m - (pcb->sv >> 2);
grzemich	0:d7bd7384a37c	1079	pcb->sv += m;
grzemich	0:d7bd7384a37c	1080	pcb->rto = (pcb->sa >> 3) + pcb->sv;
grzemich	0:d7bd7384a37c	1081
grzemich	0:d7bd7384a37c	1082	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
grzemich	0:d7bd7384a37c	1083	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
grzemich	0:d7bd7384a37c	1084
grzemich	0:d7bd7384a37c	1085	pcb->rttest = 0;
grzemich	0:d7bd7384a37c	1086	}
grzemich	0:d7bd7384a37c	1087	}
grzemich	0:d7bd7384a37c	1088
grzemich	0:d7bd7384a37c	1089	/* If the incoming segment contains data, we must process it
grzemich	0:d7bd7384a37c	1090	further. */
grzemich	0:d7bd7384a37c	1091	if (tcplen > 0) {
grzemich	0:d7bd7384a37c	1092	/* This code basically does three things:
grzemich	0:d7bd7384a37c	1093
grzemich	0:d7bd7384a37c	1094	+) If the incoming segment contains data that is the next
grzemich	0:d7bd7384a37c	1095	in-sequence data, this data is passed to the application. This
grzemich	0:d7bd7384a37c	1096	might involve trimming the first edge of the data. The rcv_nxt
grzemich	0:d7bd7384a37c	1097	variable and the advertised window are adjusted.
grzemich	0:d7bd7384a37c	1098
grzemich	0:d7bd7384a37c	1099	+) If the incoming segment has data that is above the next
grzemich	0:d7bd7384a37c	1100	sequence number expected (->rcv_nxt), the segment is placed on
grzemich	0:d7bd7384a37c	1101	the ->ooseq queue. This is done by finding the appropriate
grzemich	0:d7bd7384a37c	1102	place in the ->ooseq queue (which is ordered by sequence
grzemich	0:d7bd7384a37c	1103	number) and trim the segment in both ends if needed. An
grzemich	0:d7bd7384a37c	1104	immediate ACK is sent to indicate that we received an
grzemich	0:d7bd7384a37c	1105	out-of-sequence segment.
grzemich	0:d7bd7384a37c	1106
grzemich	0:d7bd7384a37c	1107	+) Finally, we check if the first segment on the ->ooseq queue
grzemich	0:d7bd7384a37c	1108	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
grzemich	0:d7bd7384a37c	1109	rcv_nxt > ooseq->seqno, we must trim the first edge of the
grzemich	0:d7bd7384a37c	1110	segment on ->ooseq before we adjust rcv_nxt. The data in the
grzemich	0:d7bd7384a37c	1111	segments that are now on sequence are chained onto the
grzemich	0:d7bd7384a37c	1112	incoming segment so that we only need to call the application
grzemich	0:d7bd7384a37c	1113	once.
grzemich	0:d7bd7384a37c	1114	*/
grzemich	0:d7bd7384a37c	1115
grzemich	0:d7bd7384a37c	1116	/* First, we check if we must trim the first edge. We have to do
grzemich	0:d7bd7384a37c	1117	this if the sequence number of the incoming segment is less
grzemich	0:d7bd7384a37c	1118	than rcv_nxt, and the sequence number plus the length of the
grzemich	0:d7bd7384a37c	1119	segment is larger than rcv_nxt. */
grzemich	0:d7bd7384a37c	1120	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
grzemich	0:d7bd7384a37c	1121	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
grzemich	0:d7bd7384a37c	1122	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
grzemich	0:d7bd7384a37c	1123	/* Trimming the first edge is done by pushing the payload
grzemich	0:d7bd7384a37c	1124	pointer in the pbuf downwards. This is somewhat tricky since
grzemich	0:d7bd7384a37c	1125	we do not want to discard the full contents of the pbuf up to
grzemich	0:d7bd7384a37c	1126	the new starting point of the data since we have to keep the
grzemich	0:d7bd7384a37c	1127	TCP header which is present in the first pbuf in the chain.
grzemich	0:d7bd7384a37c	1128
grzemich	0:d7bd7384a37c	1129	What is done is really quite a nasty hack: the first pbuf in
grzemich	0:d7bd7384a37c	1130	the pbuf chain is pointed to by inseg.p. Since we need to be
grzemich	0:d7bd7384a37c	1131	able to deallocate the whole pbuf, we cannot change this
grzemich	0:d7bd7384a37c	1132	inseg.p pointer to point to any of the later pbufs in the
grzemich	0:d7bd7384a37c	1133	chain. Instead, we point the ->payload pointer in the first
grzemich	0:d7bd7384a37c	1134	pbuf to data in one of the later pbufs. We also set the
grzemich	0:d7bd7384a37c	1135	inseg.data pointer to point to the right place. This way, the
grzemich	0:d7bd7384a37c	1136	->p pointer will still point to the first pbuf, but the
grzemich	0:d7bd7384a37c	1137	->p->payload pointer will point to data in another pbuf.
grzemich	0:d7bd7384a37c	1138
grzemich	0:d7bd7384a37c	1139	After we are done with adjusting the pbuf pointers we must
grzemich	0:d7bd7384a37c	1140	adjust the ->data pointer in the seg and the segment
grzemich	0:d7bd7384a37c	1141	length.*/
grzemich	0:d7bd7384a37c	1142
grzemich	0:d7bd7384a37c	1143	off = pcb->rcv_nxt - seqno;
grzemich	0:d7bd7384a37c	1144	p = inseg.p;
grzemich	0:d7bd7384a37c	1145	LWIP_ASSERT("inseg.p != NULL", inseg.p);
grzemich	0:d7bd7384a37c	1146	LWIP_ASSERT("insane offset!", (off < 0x7fff));
grzemich	0:d7bd7384a37c	1147	if (inseg.p->len < off) {
grzemich	0:d7bd7384a37c	1148	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
grzemich	0:d7bd7384a37c	1149	new_tot_len = (u16_t)(inseg.p->tot_len - off);
grzemich	0:d7bd7384a37c	1150	while (p->len < off) {
grzemich	0:d7bd7384a37c	1151	off -= p->len;
grzemich	0:d7bd7384a37c	1152	/* KJM following line changed (with addition of new_tot_len var)
grzemich	0:d7bd7384a37c	1153	to fix bug #9076
grzemich	0:d7bd7384a37c	1154	inseg.p->tot_len -= p->len; */
grzemich	0:d7bd7384a37c	1155	p->tot_len = new_tot_len;
grzemich	0:d7bd7384a37c	1156	p->len = 0;
grzemich	0:d7bd7384a37c	1157	p = p->next;
grzemich	0:d7bd7384a37c	1158	}
grzemich	0:d7bd7384a37c	1159	if(pbuf_header(p, (s16_t)-off)) {
grzemich	0:d7bd7384a37c	1160	/* Do we need to cope with this failing? Assert for now */
grzemich	0:d7bd7384a37c	1161	LWIP_ASSERT("pbuf_header failed", 0);
grzemich	0:d7bd7384a37c	1162	}
grzemich	0:d7bd7384a37c	1163	} else {
grzemich	0:d7bd7384a37c	1164	if(pbuf_header(inseg.p, (s16_t)-off)) {
grzemich	0:d7bd7384a37c	1165	/* Do we need to cope with this failing? Assert for now */
grzemich	0:d7bd7384a37c	1166	LWIP_ASSERT("pbuf_header failed", 0);
grzemich	0:d7bd7384a37c	1167	}
grzemich	0:d7bd7384a37c	1168	}
grzemich	0:d7bd7384a37c	1169	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
grzemich	0:d7bd7384a37c	1170	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
grzemich	0:d7bd7384a37c	1171	}
grzemich	0:d7bd7384a37c	1172	else {
grzemich	0:d7bd7384a37c	1173	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
grzemich	0:d7bd7384a37c	1174	/* the whole segment is < rcv_nxt */
grzemich	0:d7bd7384a37c	1175	/* must be a duplicate of a packet that has already been correctly handled */
grzemich	0:d7bd7384a37c	1176
grzemich	0:d7bd7384a37c	1177	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
grzemich	0:d7bd7384a37c	1178	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	1179	}
grzemich	0:d7bd7384a37c	1180	}
grzemich	0:d7bd7384a37c	1181
grzemich	0:d7bd7384a37c	1182	/* The sequence number must be within the window (above rcv_nxt
grzemich	0:d7bd7384a37c	1183	and below rcv_nxt + rcv_wnd) in order to be further
grzemich	0:d7bd7384a37c	1184	processed. */
grzemich	0:d7bd7384a37c	1185	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
grzemich	0:d7bd7384a37c	1186	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
grzemich	0:d7bd7384a37c	1187	if (pcb->rcv_nxt == seqno) {
grzemich	0:d7bd7384a37c	1188	/* The incoming segment is the next in sequence. We check if
grzemich	0:d7bd7384a37c	1189	we have to trim the end of the segment and update rcv_nxt
grzemich	0:d7bd7384a37c	1190	and pass the data to the application. */
grzemich	0:d7bd7384a37c	1191	tcplen = TCP_TCPLEN(&inseg);
grzemich	0:d7bd7384a37c	1192
grzemich	0:d7bd7384a37c	1193	if (tcplen > pcb->rcv_wnd) {
grzemich	0:d7bd7384a37c	1194	LWIP_DEBUGF(TCP_INPUT_DEBUG,
grzemich	0:d7bd7384a37c	1195	("tcp_receive: other end overran receive window"
grzemich	0:d7bd7384a37c	1196	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
grzemich	0:d7bd7384a37c	1197	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
grzemich	0:d7bd7384a37c	1198	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	1199	/* Must remove the FIN from the header as we're trimming
grzemich	0:d7bd7384a37c	1200	* that byte of sequence-space from the packet */
grzemich	0:d7bd7384a37c	1201	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
grzemich	0:d7bd7384a37c	1202	}
grzemich	0:d7bd7384a37c	1203	/* Adjust length of segment to fit in the window. */
grzemich	0:d7bd7384a37c	1204	inseg.len = pcb->rcv_wnd;
grzemich	0:d7bd7384a37c	1205	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
grzemich	0:d7bd7384a37c	1206	inseg.len -= 1;
grzemich	0:d7bd7384a37c	1207	}
grzemich	0:d7bd7384a37c	1208	pbuf_realloc(inseg.p, inseg.len);
grzemich	0:d7bd7384a37c	1209	tcplen = TCP_TCPLEN(&inseg);
grzemich	0:d7bd7384a37c	1210	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
grzemich	0:d7bd7384a37c	1211	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
grzemich	0:d7bd7384a37c	1212	}
grzemich	0:d7bd7384a37c	1213	#if TCP_QUEUE_OOSEQ
grzemich	0:d7bd7384a37c	1214	/* Received in-sequence data, adjust ooseq data if:
grzemich	0:d7bd7384a37c	1215	- FIN has been received or
grzemich	0:d7bd7384a37c	1216	- inseq overlaps with ooseq */
grzemich	0:d7bd7384a37c	1217	if (pcb->ooseq != NULL) {
grzemich	0:d7bd7384a37c	1218	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	1219	LWIP_DEBUGF(TCP_INPUT_DEBUG,
grzemich	0:d7bd7384a37c	1220	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
grzemich	0:d7bd7384a37c	1221	/* Received in-order FIN means anything that was received
grzemich	0:d7bd7384a37c	1222	* out of order must now have been received in-order, so
grzemich	0:d7bd7384a37c	1223	* bin the ooseq queue */
grzemich	0:d7bd7384a37c	1224	while (pcb->ooseq != NULL) {
grzemich	0:d7bd7384a37c	1225	struct tcp_seg *old_ooseq = pcb->ooseq;
grzemich	0:d7bd7384a37c	1226	pcb->ooseq = pcb->ooseq->next;
grzemich	0:d7bd7384a37c	1227	tcp_seg_free(old_ooseq);
grzemich	0:d7bd7384a37c	1228	}
grzemich	0:d7bd7384a37c	1229	}
grzemich	0:d7bd7384a37c	1230	else {
grzemich	0:d7bd7384a37c	1231	next = pcb->ooseq;
grzemich	0:d7bd7384a37c	1232	/* Remove all segments on ooseq that are covered by inseg already.
grzemich	0:d7bd7384a37c	1233	* FIN is copied from ooseq to inseg if present. */
grzemich	0:d7bd7384a37c	1234	while (next &&
grzemich	0:d7bd7384a37c	1235	TCP_SEQ_GEQ(seqno + tcplen,
grzemich	0:d7bd7384a37c	1236	next->tcphdr->seqno + next->len)) {
grzemich	0:d7bd7384a37c	1237	/* inseg cannot have FIN here (already processed above) */
grzemich	0:d7bd7384a37c	1238	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
grzemich	0:d7bd7384a37c	1239	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
grzemich	0:d7bd7384a37c	1240	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
grzemich	0:d7bd7384a37c	1241	tcplen = TCP_TCPLEN(&inseg);
grzemich	0:d7bd7384a37c	1242	}
grzemich	0:d7bd7384a37c	1243	prev = next;
grzemich	0:d7bd7384a37c	1244	next = next->next;
grzemich	0:d7bd7384a37c	1245	tcp_seg_free(prev);
grzemich	0:d7bd7384a37c	1246	}
grzemich	0:d7bd7384a37c	1247	/* Now trim right side of inseg if it overlaps with the first
grzemich	0:d7bd7384a37c	1248	* segment on ooseq */
grzemich	0:d7bd7384a37c	1249	if (next &&
grzemich	0:d7bd7384a37c	1250	TCP_SEQ_GT(seqno + tcplen,
grzemich	0:d7bd7384a37c	1251	next->tcphdr->seqno)) {
grzemich	0:d7bd7384a37c	1252	/* inseg cannot have FIN here (already processed above) */
grzemich	0:d7bd7384a37c	1253	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
grzemich	0:d7bd7384a37c	1254	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
grzemich	0:d7bd7384a37c	1255	inseg.len -= 1;
grzemich	0:d7bd7384a37c	1256	}
grzemich	0:d7bd7384a37c	1257	pbuf_realloc(inseg.p, inseg.len);
grzemich	0:d7bd7384a37c	1258	tcplen = TCP_TCPLEN(&inseg);
grzemich	0:d7bd7384a37c	1259	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
grzemich	0:d7bd7384a37c	1260	(seqno + tcplen) == next->tcphdr->seqno);
grzemich	0:d7bd7384a37c	1261	}
grzemich	0:d7bd7384a37c	1262	pcb->ooseq = next;
grzemich	0:d7bd7384a37c	1263	}
grzemich	0:d7bd7384a37c	1264	}
grzemich	0:d7bd7384a37c	1265	#endif /* TCP_QUEUE_OOSEQ */
grzemich	0:d7bd7384a37c	1266
grzemich	0:d7bd7384a37c	1267	pcb->rcv_nxt = seqno + tcplen;
grzemich	0:d7bd7384a37c	1268
grzemich	0:d7bd7384a37c	1269	/* Update the receiver's (our) window. */
grzemich	0:d7bd7384a37c	1270	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
grzemich	0:d7bd7384a37c	1271	pcb->rcv_wnd -= tcplen;
grzemich	0:d7bd7384a37c	1272
grzemich	0:d7bd7384a37c	1273	tcp_update_rcv_ann_wnd(pcb);
grzemich	0:d7bd7384a37c	1274
grzemich	0:d7bd7384a37c	1275	/* If there is data in the segment, we make preparations to
grzemich	0:d7bd7384a37c	1276	pass this up to the application. The ->recv_data variable
grzemich	0:d7bd7384a37c	1277	is used for holding the pbuf that goes to the
grzemich	0:d7bd7384a37c	1278	application. The code for reassembling out-of-sequence data
grzemich	0:d7bd7384a37c	1279	chains its data on this pbuf as well.
grzemich	0:d7bd7384a37c	1280
grzemich	0:d7bd7384a37c	1281	If the segment was a FIN, we set the TF_GOT_FIN flag that will
grzemich	0:d7bd7384a37c	1282	be used to indicate to the application that the remote side has
grzemich	0:d7bd7384a37c	1283	closed its end of the connection. */
grzemich	0:d7bd7384a37c	1284	if (inseg.p->tot_len > 0) {
grzemich	0:d7bd7384a37c	1285	recv_data = inseg.p;
grzemich	0:d7bd7384a37c	1286	/* Since this pbuf now is the responsibility of the
grzemich	0:d7bd7384a37c	1287	application, we delete our reference to it so that we won't
grzemich	0:d7bd7384a37c	1288	(mistakingly) deallocate it. */
grzemich	0:d7bd7384a37c	1289	inseg.p = NULL;
grzemich	0:d7bd7384a37c	1290	}
grzemich	0:d7bd7384a37c	1291	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	1292	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
grzemich	0:d7bd7384a37c	1293	recv_flags \|= TF_GOT_FIN;
grzemich	0:d7bd7384a37c	1294	}
grzemich	0:d7bd7384a37c	1295
grzemich	0:d7bd7384a37c	1296	#if TCP_QUEUE_OOSEQ
grzemich	0:d7bd7384a37c	1297	/* We now check if we have segments on the ->ooseq queue that
grzemich	0:d7bd7384a37c	1298	are now in sequence. */
grzemich	0:d7bd7384a37c	1299	while (pcb->ooseq != NULL &&
grzemich	0:d7bd7384a37c	1300	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
grzemich	0:d7bd7384a37c	1301
grzemich	0:d7bd7384a37c	1302	cseg = pcb->ooseq;
grzemich	0:d7bd7384a37c	1303	seqno = pcb->ooseq->tcphdr->seqno;
grzemich	0:d7bd7384a37c	1304
grzemich	0:d7bd7384a37c	1305	pcb->rcv_nxt += TCP_TCPLEN(cseg);
grzemich	0:d7bd7384a37c	1306	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
grzemich	0:d7bd7384a37c	1307	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
grzemich	0:d7bd7384a37c	1308	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
grzemich	0:d7bd7384a37c	1309
grzemich	0:d7bd7384a37c	1310	tcp_update_rcv_ann_wnd(pcb);
grzemich	0:d7bd7384a37c	1311
grzemich	0:d7bd7384a37c	1312	if (cseg->p->tot_len > 0) {
grzemich	0:d7bd7384a37c	1313	/* Chain this pbuf onto the pbuf that we will pass to
grzemich	0:d7bd7384a37c	1314	the application. */
grzemich	0:d7bd7384a37c	1315	if (recv_data) {
grzemich	0:d7bd7384a37c	1316	pbuf_cat(recv_data, cseg->p);
grzemich	0:d7bd7384a37c	1317	} else {
grzemich	0:d7bd7384a37c	1318	recv_data = cseg->p;
grzemich	0:d7bd7384a37c	1319	}
grzemich	0:d7bd7384a37c	1320	cseg->p = NULL;
grzemich	0:d7bd7384a37c	1321	}
grzemich	0:d7bd7384a37c	1322	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	1323	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
grzemich	0:d7bd7384a37c	1324	recv_flags \|= TF_GOT_FIN;
grzemich	0:d7bd7384a37c	1325	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
grzemich	0:d7bd7384a37c	1326	pcb->state = CLOSE_WAIT;
grzemich	0:d7bd7384a37c	1327	}
grzemich	0:d7bd7384a37c	1328	}
grzemich	0:d7bd7384a37c	1329
grzemich	0:d7bd7384a37c	1330	pcb->ooseq = cseg->next;
grzemich	0:d7bd7384a37c	1331	tcp_seg_free(cseg);
grzemich	0:d7bd7384a37c	1332	}
grzemich	0:d7bd7384a37c	1333	#endif /* TCP_QUEUE_OOSEQ */
grzemich	0:d7bd7384a37c	1334
grzemich	0:d7bd7384a37c	1335
grzemich	0:d7bd7384a37c	1336	/* Acknowledge the segment(s). */
grzemich	0:d7bd7384a37c	1337	tcp_ack(pcb);
grzemich	0:d7bd7384a37c	1338
grzemich	0:d7bd7384a37c	1339	} else {
grzemich	0:d7bd7384a37c	1340	/* We get here if the incoming segment is out-of-sequence. */
grzemich	0:d7bd7384a37c	1341	tcp_send_empty_ack(pcb);
grzemich	0:d7bd7384a37c	1342	#if TCP_QUEUE_OOSEQ
grzemich	0:d7bd7384a37c	1343	/* We queue the segment on the ->ooseq queue. */
grzemich	0:d7bd7384a37c	1344	if (pcb->ooseq == NULL) {
grzemich	0:d7bd7384a37c	1345	pcb->ooseq = tcp_seg_copy(&inseg);
grzemich	0:d7bd7384a37c	1346	} else {
grzemich	0:d7bd7384a37c	1347	/* If the queue is not empty, we walk through the queue and
grzemich	0:d7bd7384a37c	1348	try to find a place where the sequence number of the
grzemich	0:d7bd7384a37c	1349	incoming segment is between the sequence numbers of the
grzemich	0:d7bd7384a37c	1350	previous and the next segment on the ->ooseq queue. That is
grzemich	0:d7bd7384a37c	1351	the place where we put the incoming segment. If needed, we
grzemich	0:d7bd7384a37c	1352	trim the second edges of the previous and the incoming
grzemich	0:d7bd7384a37c	1353	segment so that it will fit into the sequence.
grzemich	0:d7bd7384a37c	1354
grzemich	0:d7bd7384a37c	1355	If the incoming segment has the same sequence number as a
grzemich	0:d7bd7384a37c	1356	segment on the ->ooseq queue, we discard the segment that
grzemich	0:d7bd7384a37c	1357	contains less data. */
grzemich	0:d7bd7384a37c	1358
grzemich	0:d7bd7384a37c	1359	prev = NULL;
grzemich	0:d7bd7384a37c	1360	for(next = pcb->ooseq; next != NULL; next = next->next) {
grzemich	0:d7bd7384a37c	1361	if (seqno == next->tcphdr->seqno) {
grzemich	0:d7bd7384a37c	1362	/* The sequence number of the incoming segment is the
grzemich	0:d7bd7384a37c	1363	same as the sequence number of the segment on
grzemich	0:d7bd7384a37c	1364	->ooseq. We check the lengths to see which one to
grzemich	0:d7bd7384a37c	1365	discard. */
grzemich	0:d7bd7384a37c	1366	if (inseg.len > next->len) {
grzemich	0:d7bd7384a37c	1367	/* The incoming segment is larger than the old
grzemich	0:d7bd7384a37c	1368	segment. We replace some segments with the new
grzemich	0:d7bd7384a37c	1369	one. */
grzemich	0:d7bd7384a37c	1370	cseg = tcp_seg_copy(&inseg);
grzemich	0:d7bd7384a37c	1371	if (cseg != NULL) {
grzemich	0:d7bd7384a37c	1372	if (prev != NULL) {
grzemich	0:d7bd7384a37c	1373	prev->next = cseg;
grzemich	0:d7bd7384a37c	1374	} else {
grzemich	0:d7bd7384a37c	1375	pcb->ooseq = cseg;
grzemich	0:d7bd7384a37c	1376	}
grzemich	0:d7bd7384a37c	1377	tcp_oos_insert_segment(cseg, next);
grzemich	0:d7bd7384a37c	1378	}
grzemich	0:d7bd7384a37c	1379	break;
grzemich	0:d7bd7384a37c	1380	} else {
grzemich	0:d7bd7384a37c	1381	/* Either the lenghts are the same or the incoming
grzemich	0:d7bd7384a37c	1382	segment was smaller than the old one; in either
grzemich	0:d7bd7384a37c	1383	case, we ditch the incoming segment. */
grzemich	0:d7bd7384a37c	1384	break;
grzemich	0:d7bd7384a37c	1385	}
grzemich	0:d7bd7384a37c	1386	} else {
grzemich	0:d7bd7384a37c	1387	if (prev == NULL) {
grzemich	0:d7bd7384a37c	1388	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
grzemich	0:d7bd7384a37c	1389	/* The sequence number of the incoming segment is lower
grzemich	0:d7bd7384a37c	1390	than the sequence number of the first segment on the
grzemich	0:d7bd7384a37c	1391	queue. We put the incoming segment first on the
grzemich	0:d7bd7384a37c	1392	queue. */
grzemich	0:d7bd7384a37c	1393	cseg = tcp_seg_copy(&inseg);
grzemich	0:d7bd7384a37c	1394	if (cseg != NULL) {
grzemich	0:d7bd7384a37c	1395	pcb->ooseq = cseg;
grzemich	0:d7bd7384a37c	1396	tcp_oos_insert_segment(cseg, next);
grzemich	0:d7bd7384a37c	1397	}
grzemich	0:d7bd7384a37c	1398	break;
grzemich	0:d7bd7384a37c	1399	}
grzemich	0:d7bd7384a37c	1400	} else {
grzemich	0:d7bd7384a37c	1401	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
grzemich	0:d7bd7384a37c	1402	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
grzemich	0:d7bd7384a37c	1403	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
grzemich	0:d7bd7384a37c	1404	/* The sequence number of the incoming segment is in
grzemich	0:d7bd7384a37c	1405	between the sequence numbers of the previous and
grzemich	0:d7bd7384a37c	1406	the next segment on ->ooseq. We trim trim the previous
grzemich	0:d7bd7384a37c	1407	segment, delete next segments that included in received segment
grzemich	0:d7bd7384a37c	1408	and trim received, if needed. */
grzemich	0:d7bd7384a37c	1409	cseg = tcp_seg_copy(&inseg);
grzemich	0:d7bd7384a37c	1410	if (cseg != NULL) {
grzemich	0:d7bd7384a37c	1411	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
grzemich	0:d7bd7384a37c	1412	/* We need to trim the prev segment. */
grzemich	0:d7bd7384a37c	1413	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
grzemich	0:d7bd7384a37c	1414	pbuf_realloc(prev->p, prev->len);
grzemich	0:d7bd7384a37c	1415	}
grzemich	0:d7bd7384a37c	1416	prev->next = cseg;
grzemich	0:d7bd7384a37c	1417	tcp_oos_insert_segment(cseg, next);
grzemich	0:d7bd7384a37c	1418	}
grzemich	0:d7bd7384a37c	1419	break;
grzemich	0:d7bd7384a37c	1420	}
grzemich	0:d7bd7384a37c	1421	}
grzemich	0:d7bd7384a37c	1422	/* If the "next" segment is the last segment on the
grzemich	0:d7bd7384a37c	1423	ooseq queue, we add the incoming segment to the end
grzemich	0:d7bd7384a37c	1424	of the list. */
grzemich	0:d7bd7384a37c	1425	if (next->next == NULL &&
grzemich	0:d7bd7384a37c	1426	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
grzemich	0:d7bd7384a37c	1427	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	1428	/* segment "next" already contains all data */
grzemich	0:d7bd7384a37c	1429	break;
grzemich	0:d7bd7384a37c	1430	}
grzemich	0:d7bd7384a37c	1431	next->next = tcp_seg_copy(&inseg);
grzemich	0:d7bd7384a37c	1432	if (next->next != NULL) {
grzemich	0:d7bd7384a37c	1433	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
grzemich	0:d7bd7384a37c	1434	/* We need to trim the last segment. */
grzemich	0:d7bd7384a37c	1435	next->len = (u16_t)(seqno - next->tcphdr->seqno);
grzemich	0:d7bd7384a37c	1436	pbuf_realloc(next->p, next->len);
grzemich	0:d7bd7384a37c	1437	}
grzemich	0:d7bd7384a37c	1438	/* check if the remote side overruns our receive window */
grzemich	0:d7bd7384a37c	1439	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
grzemich	0:d7bd7384a37c	1440	LWIP_DEBUGF(TCP_INPUT_DEBUG,
grzemich	0:d7bd7384a37c	1441	("tcp_receive: other end overran receive window"
grzemich	0:d7bd7384a37c	1442	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
grzemich	0:d7bd7384a37c	1443	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
grzemich	0:d7bd7384a37c	1444	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
grzemich	0:d7bd7384a37c	1445	/* Must remove the FIN from the header as we're trimming
grzemich	0:d7bd7384a37c	1446	* that byte of sequence-space from the packet */
grzemich	0:d7bd7384a37c	1447	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
grzemich	0:d7bd7384a37c	1448	}
grzemich	0:d7bd7384a37c	1449	/* Adjust length of segment to fit in the window. */
grzemich	0:d7bd7384a37c	1450	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
grzemich	0:d7bd7384a37c	1451	pbuf_realloc(next->next->p, next->next->len);
grzemich	0:d7bd7384a37c	1452	tcplen = TCP_TCPLEN(next->next);
grzemich	0:d7bd7384a37c	1453	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
grzemich	0:d7bd7384a37c	1454	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
grzemich	0:d7bd7384a37c	1455	}
grzemich	0:d7bd7384a37c	1456	}
grzemich	0:d7bd7384a37c	1457	break;
grzemich	0:d7bd7384a37c	1458	}
grzemich	0:d7bd7384a37c	1459	}
grzemich	0:d7bd7384a37c	1460	prev = next;
grzemich	0:d7bd7384a37c	1461	}
grzemich	0:d7bd7384a37c	1462	}
grzemich	0:d7bd7384a37c	1463	#endif /* TCP_QUEUE_OOSEQ */
grzemich	0:d7bd7384a37c	1464
grzemich	0:d7bd7384a37c	1465	}
grzemich	0:d7bd7384a37c	1466	} else {
grzemich	0:d7bd7384a37c	1467	/* The incoming segment is not withing the window. */
grzemich	0:d7bd7384a37c	1468	tcp_send_empty_ack(pcb);
grzemich	0:d7bd7384a37c	1469	}
grzemich	0:d7bd7384a37c	1470	} else {
grzemich	0:d7bd7384a37c	1471	/* Segments with length 0 is taken care of here. Segments that
grzemich	0:d7bd7384a37c	1472	fall out of the window are ACKed. */
grzemich	0:d7bd7384a37c	1473	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
grzemich	0:d7bd7384a37c	1474	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
grzemich	0:d7bd7384a37c	1475	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
grzemich	0:d7bd7384a37c	1476	tcp_ack_now(pcb);
grzemich	0:d7bd7384a37c	1477	}
grzemich	0:d7bd7384a37c	1478	}
grzemich	0:d7bd7384a37c	1479	}
grzemich	0:d7bd7384a37c	1480
grzemich	0:d7bd7384a37c	1481	/**
grzemich	0:d7bd7384a37c	1482	* Parses the options contained in the incoming segment.
grzemich	0:d7bd7384a37c	1483	*
grzemich	0:d7bd7384a37c	1484	* Called from tcp_listen_input() and tcp_process().
grzemich	0:d7bd7384a37c	1485	* Currently, only the MSS option is supported!
grzemich	0:d7bd7384a37c	1486	*
grzemich	0:d7bd7384a37c	1487	* @param pcb the tcp_pcb for which a segment arrived
grzemich	0:d7bd7384a37c	1488	*/
grzemich	0:d7bd7384a37c	1489	static void
grzemich	0:d7bd7384a37c	1490	tcp_parseopt(struct tcp_pcb *pcb)
grzemich	0:d7bd7384a37c	1491	{
grzemich	0:d7bd7384a37c	1492	u16_t c, max_c;
grzemich	0:d7bd7384a37c	1493	u16_t mss;
grzemich	0:d7bd7384a37c	1494	u8_t *opts, opt;
grzemich	0:d7bd7384a37c	1495	#if LWIP_TCP_TIMESTAMPS
grzemich	0:d7bd7384a37c	1496	u32_t tsval;
grzemich	0:d7bd7384a37c	1497	#endif
grzemich	0:d7bd7384a37c	1498
grzemich	0:d7bd7384a37c	1499	opts = (u8_t *)tcphdr + TCP_HLEN;
grzemich	0:d7bd7384a37c	1500
grzemich	0:d7bd7384a37c	1501	/* Parse the TCP MSS option, if present. */
grzemich	0:d7bd7384a37c	1502	if(TCPH_HDRLEN(tcphdr) > 0x5) {
grzemich	0:d7bd7384a37c	1503	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
grzemich	0:d7bd7384a37c	1504	for (c = 0; c < max_c; ) {
grzemich	0:d7bd7384a37c	1505	opt = opts[c];
grzemich	0:d7bd7384a37c	1506	switch (opt) {
grzemich	0:d7bd7384a37c	1507	case 0x00:
grzemich	0:d7bd7384a37c	1508	/* End of options. */
grzemich	0:d7bd7384a37c	1509	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
grzemich	0:d7bd7384a37c	1510	return;
grzemich	0:d7bd7384a37c	1511	case 0x01:
grzemich	0:d7bd7384a37c	1512	/* NOP option. */
grzemich	0:d7bd7384a37c	1513	++c;
grzemich	0:d7bd7384a37c	1514	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
grzemich	0:d7bd7384a37c	1515	break;
grzemich	0:d7bd7384a37c	1516	case 0x02:
grzemich	0:d7bd7384a37c	1517	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
grzemich	0:d7bd7384a37c	1518	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
grzemich	0:d7bd7384a37c	1519	/* Bad length */
grzemich	0:d7bd7384a37c	1520	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
grzemich	0:d7bd7384a37c	1521	return;
grzemich	0:d7bd7384a37c	1522	}
grzemich	0:d7bd7384a37c	1523	/* An MSS option with the right option length. */
grzemich	0:d7bd7384a37c	1524	mss = (opts[c + 2] << 8) \| opts[c + 3];
grzemich	0:d7bd7384a37c	1525	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
grzemich	0:d7bd7384a37c	1526	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
grzemich	0:d7bd7384a37c	1527	/* Advance to next option */
grzemich	0:d7bd7384a37c	1528	c += 0x04;
grzemich	0:d7bd7384a37c	1529	break;
grzemich	0:d7bd7384a37c	1530	#if LWIP_TCP_TIMESTAMPS
grzemich	0:d7bd7384a37c	1531	case 0x08:
grzemich	0:d7bd7384a37c	1532	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
grzemich	0:d7bd7384a37c	1533	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
grzemich	0:d7bd7384a37c	1534	/* Bad length */
grzemich	0:d7bd7384a37c	1535	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
grzemich	0:d7bd7384a37c	1536	return;
grzemich	0:d7bd7384a37c	1537	}
grzemich	0:d7bd7384a37c	1538	/* TCP timestamp option with valid length */
grzemich	0:d7bd7384a37c	1539	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
grzemich	0:d7bd7384a37c	1540	(opts[c+4] << 16) \| (opts[c+5] << 24);
grzemich	0:d7bd7384a37c	1541	if (flags & TCP_SYN) {
grzemich	0:d7bd7384a37c	1542	pcb->ts_recent = ntohl(tsval);
grzemich	0:d7bd7384a37c	1543	pcb->flags \|= TF_TIMESTAMP;
grzemich	0:d7bd7384a37c	1544	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
grzemich	0:d7bd7384a37c	1545	pcb->ts_recent = ntohl(tsval);
grzemich	0:d7bd7384a37c	1546	}
grzemich	0:d7bd7384a37c	1547	/* Advance to next option */
grzemich	0:d7bd7384a37c	1548	c += 0x0A;
grzemich	0:d7bd7384a37c	1549	break;
grzemich	0:d7bd7384a37c	1550	#endif
grzemich	0:d7bd7384a37c	1551	default:
grzemich	0:d7bd7384a37c	1552	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
grzemich	0:d7bd7384a37c	1553	if (opts[c + 1] == 0) {
grzemich	0:d7bd7384a37c	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
grzemich	0:d7bd7384a37c	1555	/* If the length field is zero, the options are malformed
grzemich	0:d7bd7384a37c	1556	and we don't process them further. */
grzemich	0:d7bd7384a37c	1557	return;
grzemich	0:d7bd7384a37c	1558	}
grzemich	0:d7bd7384a37c	1559	/* All other options have a length field, so that we easily
grzemich	0:d7bd7384a37c	1560	can skip past them. */
grzemich	0:d7bd7384a37c	1561	c += opts[c + 1];
grzemich	0:d7bd7384a37c	1562	}
grzemich	0:d7bd7384a37c	1563	}
grzemich	0:d7bd7384a37c	1564	}
grzemich	0:d7bd7384a37c	1565	}
grzemich	0:d7bd7384a37c	1566
grzemich	0:d7bd7384a37c	1567	#endif /* LWIP_TCP */

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Type:	Library
Created:	08 Dec 2016
Imports:	2280
Forks:	0
Commits:	1
Dependents:	6
Dependencies:	0
Followers:	37

lwip/core/tcp_in.c@0:d7bd7384a37c, 2016-12-07 (annotated)

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