NetServicesMod - Modified version of NetServices. Fixes an issue w…

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Modified version of NetServices. Fixes an issue where connections failed should the HTTP response status line be received in a packet on its own prior to any further headers. Changes are made to the HTTPClient.cpp file's readHeaders method.

lwip/core/tcp_in.c@0:ec559500a63f, 2011-04-08 (annotated)

Committer:: andrewbonney
Date:: Fri Apr 08 14:39:41 2011 +0000
Revision:: 0:ec559500a63f

Who changed what in which revision?

User	Revision	Line number	New contents of line
andrewbonney	0:ec559500a63f	1	/**
andrewbonney	0:ec559500a63f	2	* @file
andrewbonney	0:ec559500a63f	3	* Transmission Control Protocol, incoming traffic
andrewbonney	0:ec559500a63f	4	*
andrewbonney	0:ec559500a63f	5	* The input processing functions of the TCP layer.
andrewbonney	0:ec559500a63f	6	*
andrewbonney	0:ec559500a63f	7	* These functions are generally called in the order (ip_input() ->)
andrewbonney	0:ec559500a63f	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
andrewbonney	0:ec559500a63f	9	*
andrewbonney	0:ec559500a63f	10	*/
andrewbonney	0:ec559500a63f	11
andrewbonney	0:ec559500a63f	12	/*
andrewbonney	0:ec559500a63f	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
andrewbonney	0:ec559500a63f	14	* All rights reserved.
andrewbonney	0:ec559500a63f	15	*
andrewbonney	0:ec559500a63f	16	* Redistribution and use in source and binary forms, with or without modification,
andrewbonney	0:ec559500a63f	17	* are permitted provided that the following conditions are met:
andrewbonney	0:ec559500a63f	18	*
andrewbonney	0:ec559500a63f	19	* 1. Redistributions of source code must retain the above copyright notice,
andrewbonney	0:ec559500a63f	20	* this list of conditions and the following disclaimer.
andrewbonney	0:ec559500a63f	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
andrewbonney	0:ec559500a63f	22	* this list of conditions and the following disclaimer in the documentation
andrewbonney	0:ec559500a63f	23	* and/or other materials provided with the distribution.
andrewbonney	0:ec559500a63f	24	* 3. The name of the author may not be used to endorse or promote products
andrewbonney	0:ec559500a63f	25	* derived from this software without specific prior written permission.
andrewbonney	0:ec559500a63f	26	*
andrewbonney	0:ec559500a63f	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
andrewbonney	0:ec559500a63f	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
andrewbonney	0:ec559500a63f	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
andrewbonney	0:ec559500a63f	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
andrewbonney	0:ec559500a63f	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
andrewbonney	0:ec559500a63f	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
andrewbonney	0:ec559500a63f	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
andrewbonney	0:ec559500a63f	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
andrewbonney	0:ec559500a63f	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
andrewbonney	0:ec559500a63f	36	* OF SUCH DAMAGE.
andrewbonney	0:ec559500a63f	37	*
andrewbonney	0:ec559500a63f	38	* This file is part of the lwIP TCP/IP stack.
andrewbonney	0:ec559500a63f	39	*
andrewbonney	0:ec559500a63f	40	* Author: Adam Dunkels <adam@sics.se>
andrewbonney	0:ec559500a63f	41	*
andrewbonney	0:ec559500a63f	42	*/
andrewbonney	0:ec559500a63f	43
andrewbonney	0:ec559500a63f	44	#include "lwip/opt.h"
andrewbonney	0:ec559500a63f	45
andrewbonney	0:ec559500a63f	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
andrewbonney	0:ec559500a63f	47
andrewbonney	0:ec559500a63f	48	#include "lwip/tcp_impl.h"
andrewbonney	0:ec559500a63f	49	#include "lwip/def.h"
andrewbonney	0:ec559500a63f	50	#include "lwip/ip_addr.h"
andrewbonney	0:ec559500a63f	51	#include "lwip/netif.h"
andrewbonney	0:ec559500a63f	52	#include "lwip/mem.h"
andrewbonney	0:ec559500a63f	53	#include "lwip/memp.h"
andrewbonney	0:ec559500a63f	54	#include "lwip/inet_chksum.h"
andrewbonney	0:ec559500a63f	55	#include "lwip/stats.h"
andrewbonney	0:ec559500a63f	56	#include "lwip/snmp.h"
andrewbonney	0:ec559500a63f	57	#include "arch/perf.h"
andrewbonney	0:ec559500a63f	58
andrewbonney	0:ec559500a63f	59	/* These variables are global to all functions involved in the input
andrewbonney	0:ec559500a63f	60	processing of TCP segments. They are set by the tcp_input()
andrewbonney	0:ec559500a63f	61	function. */
andrewbonney	0:ec559500a63f	62	static struct tcp_seg inseg;
andrewbonney	0:ec559500a63f	63	static struct tcp_hdr *tcphdr;
andrewbonney	0:ec559500a63f	64	static struct ip_hdr *iphdr;
andrewbonney	0:ec559500a63f	65	static u32_t seqno, ackno;
andrewbonney	0:ec559500a63f	66	static u8_t flags;
andrewbonney	0:ec559500a63f	67	static u16_t tcplen;
andrewbonney	0:ec559500a63f	68
andrewbonney	0:ec559500a63f	69	static u8_t recv_flags;
andrewbonney	0:ec559500a63f	70	static struct pbuf *recv_data;
andrewbonney	0:ec559500a63f	71
andrewbonney	0:ec559500a63f	72	struct tcp_pcb *tcp_input_pcb;
andrewbonney	0:ec559500a63f	73
andrewbonney	0:ec559500a63f	74	/* Forward declarations. */
andrewbonney	0:ec559500a63f	75	static err_t tcp_process(struct tcp_pcb *pcb);
andrewbonney	0:ec559500a63f	76	static void tcp_receive(struct tcp_pcb *pcb);
andrewbonney	0:ec559500a63f	77	static void tcp_parseopt(struct tcp_pcb *pcb);
andrewbonney	0:ec559500a63f	78
andrewbonney	0:ec559500a63f	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
andrewbonney	0:ec559500a63f	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
andrewbonney	0:ec559500a63f	81
andrewbonney	0:ec559500a63f	82	/**
andrewbonney	0:ec559500a63f	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
andrewbonney	0:ec559500a63f	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
andrewbonney	0:ec559500a63f	85	* the TCP finite state machine. This function is called by the IP layer (in
andrewbonney	0:ec559500a63f	86	* ip_input()).
andrewbonney	0:ec559500a63f	87	*
andrewbonney	0:ec559500a63f	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
andrewbonney	0:ec559500a63f	89	* @param inp network interface on which this segment was received
andrewbonney	0:ec559500a63f	90	*/
andrewbonney	0:ec559500a63f	91	void
andrewbonney	0:ec559500a63f	92	tcp_input(struct pbuf p, struct netif inp)
andrewbonney	0:ec559500a63f	93	{
andrewbonney	0:ec559500a63f	94	struct tcp_pcb pcb, prev;
andrewbonney	0:ec559500a63f	95	struct tcp_pcb_listen *lpcb;
andrewbonney	0:ec559500a63f	96	#if SO_REUSE
andrewbonney	0:ec559500a63f	97	struct tcp_pcb *lpcb_prev = NULL;
andrewbonney	0:ec559500a63f	98	struct tcp_pcb_listen *lpcb_any = NULL;
andrewbonney	0:ec559500a63f	99	#endif /* SO_REUSE */
andrewbonney	0:ec559500a63f	100	u8_t hdrlen;
andrewbonney	0:ec559500a63f	101	err_t err;
andrewbonney	0:ec559500a63f	102
andrewbonney	0:ec559500a63f	103	PERF_START;
andrewbonney	0:ec559500a63f	104
andrewbonney	0:ec559500a63f	105	TCP_STATS_INC(tcp.recv);
andrewbonney	0:ec559500a63f	106	snmp_inc_tcpinsegs();
andrewbonney	0:ec559500a63f	107
andrewbonney	0:ec559500a63f	108	iphdr = (struct ip_hdr *)p->payload;
andrewbonney	0:ec559500a63f	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
andrewbonney	0:ec559500a63f	110
andrewbonney	0:ec559500a63f	111	#if TCP_INPUT_DEBUG
andrewbonney	0:ec559500a63f	112	tcp_debug_print(tcphdr);
andrewbonney	0:ec559500a63f	113	#endif
andrewbonney	0:ec559500a63f	114
andrewbonney	0:ec559500a63f	115	/* remove header from payload */
andrewbonney	0:ec559500a63f	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
andrewbonney	0:ec559500a63f	117	/* drop short packets */
andrewbonney	0:ec559500a63f	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
andrewbonney	0:ec559500a63f	119	TCP_STATS_INC(tcp.lenerr);
andrewbonney	0:ec559500a63f	120	TCP_STATS_INC(tcp.drop);
andrewbonney	0:ec559500a63f	121	snmp_inc_tcpinerrs();
andrewbonney	0:ec559500a63f	122	pbuf_free(p);
andrewbonney	0:ec559500a63f	123	return;
andrewbonney	0:ec559500a63f	124	}
andrewbonney	0:ec559500a63f	125
andrewbonney	0:ec559500a63f	126	/* Don't even process incoming broadcasts/multicasts. */
andrewbonney	0:ec559500a63f	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
andrewbonney	0:ec559500a63f	128	ip_addr_ismulticast(&current_iphdr_dest)) {
andrewbonney	0:ec559500a63f	129	TCP_STATS_INC(tcp.proterr);
andrewbonney	0:ec559500a63f	130	TCP_STATS_INC(tcp.drop);
andrewbonney	0:ec559500a63f	131	snmp_inc_tcpinerrs();
andrewbonney	0:ec559500a63f	132	pbuf_free(p);
andrewbonney	0:ec559500a63f	133	return;
andrewbonney	0:ec559500a63f	134	}
andrewbonney	0:ec559500a63f	135
andrewbonney	0:ec559500a63f	136	#if CHECKSUM_CHECK_TCP
andrewbonney	0:ec559500a63f	137	/* Verify TCP checksum. */
andrewbonney	0:ec559500a63f	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
andrewbonney	0:ec559500a63f	139	IP_PROTO_TCP, p->tot_len) != 0) {
andrewbonney	0:ec559500a63f	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
andrewbonney	0:ec559500a63f	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
andrewbonney	0:ec559500a63f	142	IP_PROTO_TCP, p->tot_len)));
andrewbonney	0:ec559500a63f	143	#if TCP_DEBUG
andrewbonney	0:ec559500a63f	144	tcp_debug_print(tcphdr);
andrewbonney	0:ec559500a63f	145	#endif /* TCP_DEBUG */
andrewbonney	0:ec559500a63f	146	TCP_STATS_INC(tcp.chkerr);
andrewbonney	0:ec559500a63f	147	TCP_STATS_INC(tcp.drop);
andrewbonney	0:ec559500a63f	148	snmp_inc_tcpinerrs();
andrewbonney	0:ec559500a63f	149	pbuf_free(p);
andrewbonney	0:ec559500a63f	150	return;
andrewbonney	0:ec559500a63f	151	}
andrewbonney	0:ec559500a63f	152	#endif
andrewbonney	0:ec559500a63f	153
andrewbonney	0:ec559500a63f	154	/* Move the payload pointer in the pbuf so that it points to the
andrewbonney	0:ec559500a63f	155	TCP data instead of the TCP header. */
andrewbonney	0:ec559500a63f	156	hdrlen = TCPH_HDRLEN(tcphdr);
andrewbonney	0:ec559500a63f	157	if(pbuf_header(p, -(hdrlen * 4))){
andrewbonney	0:ec559500a63f	158	/* drop short packets */
andrewbonney	0:ec559500a63f	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
andrewbonney	0:ec559500a63f	160	TCP_STATS_INC(tcp.lenerr);
andrewbonney	0:ec559500a63f	161	TCP_STATS_INC(tcp.drop);
andrewbonney	0:ec559500a63f	162	snmp_inc_tcpinerrs();
andrewbonney	0:ec559500a63f	163	pbuf_free(p);
andrewbonney	0:ec559500a63f	164	return;
andrewbonney	0:ec559500a63f	165	}
andrewbonney	0:ec559500a63f	166
andrewbonney	0:ec559500a63f	167	/* Convert fields in TCP header to host byte order. */
andrewbonney	0:ec559500a63f	168	tcphdr->src = ntohs(tcphdr->src);
andrewbonney	0:ec559500a63f	169	tcphdr->dest = ntohs(tcphdr->dest);
andrewbonney	0:ec559500a63f	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
andrewbonney	0:ec559500a63f	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
andrewbonney	0:ec559500a63f	172	tcphdr->wnd = ntohs(tcphdr->wnd);
andrewbonney	0:ec559500a63f	173
andrewbonney	0:ec559500a63f	174	flags = TCPH_FLAGS(tcphdr);
andrewbonney	0:ec559500a63f	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
andrewbonney	0:ec559500a63f	176
andrewbonney	0:ec559500a63f	177	/* Demultiplex an incoming segment. First, we check if it is destined
andrewbonney	0:ec559500a63f	178	for an active connection. */
andrewbonney	0:ec559500a63f	179	prev = NULL;
andrewbonney	0:ec559500a63f	180
andrewbonney	0:ec559500a63f	181
andrewbonney	0:ec559500a63f	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
andrewbonney	0:ec559500a63f	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
andrewbonney	0:ec559500a63f	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
andrewbonney	0:ec559500a63f	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
andrewbonney	0:ec559500a63f	186	if (pcb->remote_port == tcphdr->src &&
andrewbonney	0:ec559500a63f	187	pcb->local_port == tcphdr->dest &&
andrewbonney	0:ec559500a63f	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
andrewbonney	0:ec559500a63f	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
andrewbonney	0:ec559500a63f	190
andrewbonney	0:ec559500a63f	191	/* Move this PCB to the front of the list so that subsequent
andrewbonney	0:ec559500a63f	192	lookups will be faster (we exploit locality in TCP segment
andrewbonney	0:ec559500a63f	193	arrivals). */
andrewbonney	0:ec559500a63f	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
andrewbonney	0:ec559500a63f	195	if (prev != NULL) {
andrewbonney	0:ec559500a63f	196	prev->next = pcb->next;
andrewbonney	0:ec559500a63f	197	pcb->next = tcp_active_pcbs;
andrewbonney	0:ec559500a63f	198	tcp_active_pcbs = pcb;
andrewbonney	0:ec559500a63f	199	}
andrewbonney	0:ec559500a63f	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
andrewbonney	0:ec559500a63f	201	break;
andrewbonney	0:ec559500a63f	202	}
andrewbonney	0:ec559500a63f	203	prev = pcb;
andrewbonney	0:ec559500a63f	204	}
andrewbonney	0:ec559500a63f	205
andrewbonney	0:ec559500a63f	206	if (pcb == NULL) {
andrewbonney	0:ec559500a63f	207	/* If it did not go to an active connection, we check the connections
andrewbonney	0:ec559500a63f	208	in the TIME-WAIT state. */
andrewbonney	0:ec559500a63f	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
andrewbonney	0:ec559500a63f	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
andrewbonney	0:ec559500a63f	211	if (pcb->remote_port == tcphdr->src &&
andrewbonney	0:ec559500a63f	212	pcb->local_port == tcphdr->dest &&
andrewbonney	0:ec559500a63f	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
andrewbonney	0:ec559500a63f	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
andrewbonney	0:ec559500a63f	215	/* We don't really care enough to move this PCB to the front
andrewbonney	0:ec559500a63f	216	of the list since we are not very likely to receive that
andrewbonney	0:ec559500a63f	217	many segments for connections in TIME-WAIT. */
andrewbonney	0:ec559500a63f	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
andrewbonney	0:ec559500a63f	219	tcp_timewait_input(pcb);
andrewbonney	0:ec559500a63f	220	pbuf_free(p);
andrewbonney	0:ec559500a63f	221	return;
andrewbonney	0:ec559500a63f	222	}
andrewbonney	0:ec559500a63f	223	}
andrewbonney	0:ec559500a63f	224
andrewbonney	0:ec559500a63f	225	/* Finally, if we still did not get a match, we check all PCBs that
andrewbonney	0:ec559500a63f	226	are LISTENing for incoming connections. */
andrewbonney	0:ec559500a63f	227	prev = NULL;
andrewbonney	0:ec559500a63f	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
andrewbonney	0:ec559500a63f	229	if (lpcb->local_port == tcphdr->dest) {
andrewbonney	0:ec559500a63f	230	#if SO_REUSE
andrewbonney	0:ec559500a63f	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
andrewbonney	0:ec559500a63f	232	/* found an exact match */
andrewbonney	0:ec559500a63f	233	break;
andrewbonney	0:ec559500a63f	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
andrewbonney	0:ec559500a63f	235	/* found an ANY-match */
andrewbonney	0:ec559500a63f	236	lpcb_any = lpcb;
andrewbonney	0:ec559500a63f	237	lpcb_prev = prev;
andrewbonney	0:ec559500a63f	238	}
andrewbonney	0:ec559500a63f	239	#else /* SO_REUSE */
andrewbonney	0:ec559500a63f	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
andrewbonney	0:ec559500a63f	241	ip_addr_isany(&(lpcb->local_ip))) {
andrewbonney	0:ec559500a63f	242	/* found a match */
andrewbonney	0:ec559500a63f	243	break;
andrewbonney	0:ec559500a63f	244	}
andrewbonney	0:ec559500a63f	245	#endif /* SO_REUSE */
andrewbonney	0:ec559500a63f	246	}
andrewbonney	0:ec559500a63f	247	prev = (struct tcp_pcb *)lpcb;
andrewbonney	0:ec559500a63f	248	}
andrewbonney	0:ec559500a63f	249	#if SO_REUSE
andrewbonney	0:ec559500a63f	250	/* first try specific local IP */
andrewbonney	0:ec559500a63f	251	if (lpcb == NULL) {
andrewbonney	0:ec559500a63f	252	/* only pass to ANY if no specific local IP has been found */
andrewbonney	0:ec559500a63f	253	lpcb = lpcb_any;
andrewbonney	0:ec559500a63f	254	prev = lpcb_prev;
andrewbonney	0:ec559500a63f	255	}
andrewbonney	0:ec559500a63f	256	#endif /* SO_REUSE */
andrewbonney	0:ec559500a63f	257	if (lpcb != NULL) {
andrewbonney	0:ec559500a63f	258	/* Move this PCB to the front of the list so that subsequent
andrewbonney	0:ec559500a63f	259	lookups will be faster (we exploit locality in TCP segment
andrewbonney	0:ec559500a63f	260	arrivals). */
andrewbonney	0:ec559500a63f	261	if (prev != NULL) {
andrewbonney	0:ec559500a63f	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
andrewbonney	0:ec559500a63f	263	/* our successor is the remainder of the listening list */
andrewbonney	0:ec559500a63f	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
andrewbonney	0:ec559500a63f	265	/* put this listening pcb at the head of the listening list */
andrewbonney	0:ec559500a63f	266	tcp_listen_pcbs.listen_pcbs = lpcb;
andrewbonney	0:ec559500a63f	267	}
andrewbonney	0:ec559500a63f	268
andrewbonney	0:ec559500a63f	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
andrewbonney	0:ec559500a63f	270	tcp_listen_input(lpcb);
andrewbonney	0:ec559500a63f	271	pbuf_free(p);
andrewbonney	0:ec559500a63f	272	return;
andrewbonney	0:ec559500a63f	273	}
andrewbonney	0:ec559500a63f	274	}
andrewbonney	0:ec559500a63f	275
andrewbonney	0:ec559500a63f	276	#if TCP_INPUT_DEBUG
andrewbonney	0:ec559500a63f	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
andrewbonney	0:ec559500a63f	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
andrewbonney	0:ec559500a63f	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
andrewbonney	0:ec559500a63f	280	#endif /* TCP_INPUT_DEBUG */
andrewbonney	0:ec559500a63f	281
andrewbonney	0:ec559500a63f	282
andrewbonney	0:ec559500a63f	283	if (pcb != NULL) {
andrewbonney	0:ec559500a63f	284	/* The incoming segment belongs to a connection. */
andrewbonney	0:ec559500a63f	285	#if TCP_INPUT_DEBUG
andrewbonney	0:ec559500a63f	286	#if TCP_DEBUG
andrewbonney	0:ec559500a63f	287	tcp_debug_print_state(pcb->state);
andrewbonney	0:ec559500a63f	288	#endif /* TCP_DEBUG */
andrewbonney	0:ec559500a63f	289	#endif /* TCP_INPUT_DEBUG */
andrewbonney	0:ec559500a63f	290
andrewbonney	0:ec559500a63f	291	/* Set up a tcp_seg structure. */
andrewbonney	0:ec559500a63f	292	inseg.next = NULL;
andrewbonney	0:ec559500a63f	293	inseg.len = p->tot_len;
andrewbonney	0:ec559500a63f	294	inseg.dataptr = p->payload;
andrewbonney	0:ec559500a63f	295	inseg.p = p;
andrewbonney	0:ec559500a63f	296	inseg.tcphdr = tcphdr;
andrewbonney	0:ec559500a63f	297
andrewbonney	0:ec559500a63f	298	recv_data = NULL;
andrewbonney	0:ec559500a63f	299	recv_flags = 0;
andrewbonney	0:ec559500a63f	300
andrewbonney	0:ec559500a63f	301	/* If there is data which was previously "refused" by upper layer */
andrewbonney	0:ec559500a63f	302	if (pcb->refused_data != NULL) {
andrewbonney	0:ec559500a63f	303	/* Notify again application with data previously received. */
andrewbonney	0:ec559500a63f	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
andrewbonney	0:ec559500a63f	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
andrewbonney	0:ec559500a63f	306	if (err == ERR_OK) {
andrewbonney	0:ec559500a63f	307	pcb->refused_data = NULL;
andrewbonney	0:ec559500a63f	308	} else {
andrewbonney	0:ec559500a63f	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
andrewbonney	0:ec559500a63f	310	/* drop incoming packets, because pcb is "full" */
andrewbonney	0:ec559500a63f	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
andrewbonney	0:ec559500a63f	312	TCP_STATS_INC(tcp.drop);
andrewbonney	0:ec559500a63f	313	snmp_inc_tcpinerrs();
andrewbonney	0:ec559500a63f	314	pbuf_free(p);
andrewbonney	0:ec559500a63f	315	return;
andrewbonney	0:ec559500a63f	316	}
andrewbonney	0:ec559500a63f	317	}
andrewbonney	0:ec559500a63f	318	tcp_input_pcb = pcb;
andrewbonney	0:ec559500a63f	319	err = tcp_process(pcb);
andrewbonney	0:ec559500a63f	320	/* A return value of ERR_ABRT means that tcp_abort() was called
andrewbonney	0:ec559500a63f	321	and that the pcb has been freed. If so, we don't do anything. */
andrewbonney	0:ec559500a63f	322	if (err != ERR_ABRT) {
andrewbonney	0:ec559500a63f	323	if (recv_flags & TF_RESET) {
andrewbonney	0:ec559500a63f	324	/* TF_RESET means that the connection was reset by the other
andrewbonney	0:ec559500a63f	325	end. We then call the error callback to inform the
andrewbonney	0:ec559500a63f	326	application that the connection is dead before we
andrewbonney	0:ec559500a63f	327	deallocate the PCB. */
andrewbonney	0:ec559500a63f	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
andrewbonney	0:ec559500a63f	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
andrewbonney	0:ec559500a63f	330	memp_free(MEMP_TCP_PCB, pcb);
andrewbonney	0:ec559500a63f	331	} else if (recv_flags & TF_CLOSED) {
andrewbonney	0:ec559500a63f	332	/* The connection has been closed and we will deallocate the
andrewbonney	0:ec559500a63f	333	PCB. */
andrewbonney	0:ec559500a63f	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
andrewbonney	0:ec559500a63f	335	memp_free(MEMP_TCP_PCB, pcb);
andrewbonney	0:ec559500a63f	336	} else {
andrewbonney	0:ec559500a63f	337	err = ERR_OK;
andrewbonney	0:ec559500a63f	338	/* If the application has registered a "sent" function to be
andrewbonney	0:ec559500a63f	339	called when new send buffer space is available, we call it
andrewbonney	0:ec559500a63f	340	now. */
andrewbonney	0:ec559500a63f	341	if (pcb->acked > 0) {
andrewbonney	0:ec559500a63f	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
andrewbonney	0:ec559500a63f	343	if (err == ERR_ABRT) {
andrewbonney	0:ec559500a63f	344	goto aborted;
andrewbonney	0:ec559500a63f	345	}
andrewbonney	0:ec559500a63f	346	}
andrewbonney	0:ec559500a63f	347
andrewbonney	0:ec559500a63f	348	if (recv_data != NULL) {
andrewbonney	0:ec559500a63f	349	if (pcb->flags & TF_RXCLOSED) {
andrewbonney	0:ec559500a63f	350	/* received data although already closed -> abort (send RST) to
andrewbonney	0:ec559500a63f	351	notify the remote host that not all data has been processed */
andrewbonney	0:ec559500a63f	352	pbuf_free(recv_data);
andrewbonney	0:ec559500a63f	353	tcp_abort(pcb);
andrewbonney	0:ec559500a63f	354	goto aborted;
andrewbonney	0:ec559500a63f	355	}
andrewbonney	0:ec559500a63f	356	if (flags & TCP_PSH) {
andrewbonney	0:ec559500a63f	357	recv_data->flags \|= PBUF_FLAG_PUSH;
andrewbonney	0:ec559500a63f	358	}
andrewbonney	0:ec559500a63f	359
andrewbonney	0:ec559500a63f	360	/* Notify application that data has been received. */
andrewbonney	0:ec559500a63f	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
andrewbonney	0:ec559500a63f	362	if (err == ERR_ABRT) {
andrewbonney	0:ec559500a63f	363	goto aborted;
andrewbonney	0:ec559500a63f	364	}
andrewbonney	0:ec559500a63f	365
andrewbonney	0:ec559500a63f	366	/* If the upper layer can't receive this data, store it */
andrewbonney	0:ec559500a63f	367	if (err != ERR_OK) {
andrewbonney	0:ec559500a63f	368	pcb->refused_data = recv_data;
andrewbonney	0:ec559500a63f	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
andrewbonney	0:ec559500a63f	370	}
andrewbonney	0:ec559500a63f	371	}
andrewbonney	0:ec559500a63f	372
andrewbonney	0:ec559500a63f	373	/* If a FIN segment was received, we call the callback
andrewbonney	0:ec559500a63f	374	function with a NULL buffer to indicate EOF. */
andrewbonney	0:ec559500a63f	375	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:ec559500a63f	376	/* correct rcv_wnd as the application won't call tcp_recved()
andrewbonney	0:ec559500a63f	377	for the FIN's seqno */
andrewbonney	0:ec559500a63f	378	if (pcb->rcv_wnd != TCP_WND) {
andrewbonney	0:ec559500a63f	379	pcb->rcv_wnd++;
andrewbonney	0:ec559500a63f	380	}
andrewbonney	0:ec559500a63f	381	TCP_EVENT_CLOSED(pcb, err);
andrewbonney	0:ec559500a63f	382	if (err == ERR_ABRT) {
andrewbonney	0:ec559500a63f	383	goto aborted;
andrewbonney	0:ec559500a63f	384	}
andrewbonney	0:ec559500a63f	385	}
andrewbonney	0:ec559500a63f	386
andrewbonney	0:ec559500a63f	387	tcp_input_pcb = NULL;
andrewbonney	0:ec559500a63f	388	/* Try to send something out. */
andrewbonney	0:ec559500a63f	389	tcp_output(pcb);
andrewbonney	0:ec559500a63f	390	#if TCP_INPUT_DEBUG
andrewbonney	0:ec559500a63f	391	#if TCP_DEBUG
andrewbonney	0:ec559500a63f	392	tcp_debug_print_state(pcb->state);
andrewbonney	0:ec559500a63f	393	#endif /* TCP_DEBUG */
andrewbonney	0:ec559500a63f	394	#endif /* TCP_INPUT_DEBUG */
andrewbonney	0:ec559500a63f	395	}
andrewbonney	0:ec559500a63f	396	}
andrewbonney	0:ec559500a63f	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
andrewbonney	0:ec559500a63f	398	Below this line, 'pcb' may not be dereferenced! */
andrewbonney	0:ec559500a63f	399	aborted:
andrewbonney	0:ec559500a63f	400	tcp_input_pcb = NULL;
andrewbonney	0:ec559500a63f	401	recv_data = NULL;
andrewbonney	0:ec559500a63f	402
andrewbonney	0:ec559500a63f	403	/* give up our reference to inseg.p */
andrewbonney	0:ec559500a63f	404	if (inseg.p != NULL)
andrewbonney	0:ec559500a63f	405	{
andrewbonney	0:ec559500a63f	406	pbuf_free(inseg.p);
andrewbonney	0:ec559500a63f	407	inseg.p = NULL;
andrewbonney	0:ec559500a63f	408	}
andrewbonney	0:ec559500a63f	409	} else {
andrewbonney	0:ec559500a63f	410
andrewbonney	0:ec559500a63f	411	/* If no matching PCB was found, send a TCP RST (reset) to the
andrewbonney	0:ec559500a63f	412	sender. */
andrewbonney	0:ec559500a63f	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
andrewbonney	0:ec559500a63f	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
andrewbonney	0:ec559500a63f	415	TCP_STATS_INC(tcp.proterr);
andrewbonney	0:ec559500a63f	416	TCP_STATS_INC(tcp.drop);
andrewbonney	0:ec559500a63f	417	tcp_rst(ackno, seqno + tcplen,
andrewbonney	0:ec559500a63f	418	ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:ec559500a63f	419	tcphdr->dest, tcphdr->src);
andrewbonney	0:ec559500a63f	420	}
andrewbonney	0:ec559500a63f	421	pbuf_free(p);
andrewbonney	0:ec559500a63f	422	}
andrewbonney	0:ec559500a63f	423
andrewbonney	0:ec559500a63f	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
andrewbonney	0:ec559500a63f	425	PERF_STOP("tcp_input");
andrewbonney	0:ec559500a63f	426	}
andrewbonney	0:ec559500a63f	427
andrewbonney	0:ec559500a63f	428	/**
andrewbonney	0:ec559500a63f	429	* Called by tcp_input() when a segment arrives for a listening
andrewbonney	0:ec559500a63f	430	* connection (from tcp_input()).
andrewbonney	0:ec559500a63f	431	*
andrewbonney	0:ec559500a63f	432	* @param pcb the tcp_pcb_listen for which a segment arrived
andrewbonney	0:ec559500a63f	433	* @return ERR_OK if the segment was processed
andrewbonney	0:ec559500a63f	434	* another err_t on error
andrewbonney	0:ec559500a63f	435	*
andrewbonney	0:ec559500a63f	436	* @note the return value is not (yet?) used in tcp_input()
andrewbonney	0:ec559500a63f	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
andrewbonney	0:ec559500a63f	438	* involved is passed as a parameter to this function
andrewbonney	0:ec559500a63f	439	*/
andrewbonney	0:ec559500a63f	440	static err_t
andrewbonney	0:ec559500a63f	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
andrewbonney	0:ec559500a63f	442	{
andrewbonney	0:ec559500a63f	443	struct tcp_pcb *npcb;
andrewbonney	0:ec559500a63f	444	err_t rc;
andrewbonney	0:ec559500a63f	445
andrewbonney	0:ec559500a63f	446	/* In the LISTEN state, we check for incoming SYN segments,
andrewbonney	0:ec559500a63f	447	creates a new PCB, and responds with a SYN\|ACK. */
andrewbonney	0:ec559500a63f	448	if (flags & TCP_ACK) {
andrewbonney	0:ec559500a63f	449	/* For incoming segments with the ACK flag set, respond with a
andrewbonney	0:ec559500a63f	450	RST. */
andrewbonney	0:ec559500a63f	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
andrewbonney	0:ec559500a63f	452	tcp_rst(ackno + 1, seqno + tcplen,
andrewbonney	0:ec559500a63f	453	ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:ec559500a63f	454	tcphdr->dest, tcphdr->src);
andrewbonney	0:ec559500a63f	455	} else if (flags & TCP_SYN) {
andrewbonney	0:ec559500a63f	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
andrewbonney	0:ec559500a63f	457	#if TCP_LISTEN_BACKLOG
andrewbonney	0:ec559500a63f	458	if (pcb->accepts_pending >= pcb->backlog) {
andrewbonney	0:ec559500a63f	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
andrewbonney	0:ec559500a63f	460	return ERR_ABRT;
andrewbonney	0:ec559500a63f	461	}
andrewbonney	0:ec559500a63f	462	#endif /* TCP_LISTEN_BACKLOG */
andrewbonney	0:ec559500a63f	463	npcb = tcp_alloc(pcb->prio);
andrewbonney	0:ec559500a63f	464	/* If a new PCB could not be created (probably due to lack of memory),
andrewbonney	0:ec559500a63f	465	we don't do anything, but rely on the sender will retransmit the
andrewbonney	0:ec559500a63f	466	SYN at a time when we have more memory available. */
andrewbonney	0:ec559500a63f	467	if (npcb == NULL) {
andrewbonney	0:ec559500a63f	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
andrewbonney	0:ec559500a63f	469	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:ec559500a63f	470	return ERR_MEM;
andrewbonney	0:ec559500a63f	471	}
andrewbonney	0:ec559500a63f	472	#if TCP_LISTEN_BACKLOG
andrewbonney	0:ec559500a63f	473	pcb->accepts_pending++;
andrewbonney	0:ec559500a63f	474	#endif /* TCP_LISTEN_BACKLOG */
andrewbonney	0:ec559500a63f	475	/* Set up the new PCB. */
andrewbonney	0:ec559500a63f	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
andrewbonney	0:ec559500a63f	477	npcb->local_port = pcb->local_port;
andrewbonney	0:ec559500a63f	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
andrewbonney	0:ec559500a63f	479	npcb->remote_port = tcphdr->src;
andrewbonney	0:ec559500a63f	480	npcb->state = SYN_RCVD;
andrewbonney	0:ec559500a63f	481	npcb->rcv_nxt = seqno + 1;
andrewbonney	0:ec559500a63f	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
andrewbonney	0:ec559500a63f	483	npcb->snd_wnd = tcphdr->wnd;
andrewbonney	0:ec559500a63f	484	npcb->ssthresh = npcb->snd_wnd;
andrewbonney	0:ec559500a63f	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
andrewbonney	0:ec559500a63f	486	npcb->callback_arg = pcb->callback_arg;
andrewbonney	0:ec559500a63f	487	#if LWIP_CALLBACK_API
andrewbonney	0:ec559500a63f	488	npcb->accept = pcb->accept;
andrewbonney	0:ec559500a63f	489	#endif /* LWIP_CALLBACK_API */
andrewbonney	0:ec559500a63f	490	/* inherit socket options */
andrewbonney	0:ec559500a63f	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
andrewbonney	0:ec559500a63f	492	/* Register the new PCB so that we can begin receiving segments
andrewbonney	0:ec559500a63f	493	for it. */
andrewbonney	0:ec559500a63f	494	TCP_REG(&tcp_active_pcbs, npcb);
andrewbonney	0:ec559500a63f	495
andrewbonney	0:ec559500a63f	496	/* Parse any options in the SYN. */
andrewbonney	0:ec559500a63f	497	tcp_parseopt(npcb);
andrewbonney	0:ec559500a63f	498	#if TCP_CALCULATE_EFF_SEND_MSS
andrewbonney	0:ec559500a63f	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
andrewbonney	0:ec559500a63f	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
andrewbonney	0:ec559500a63f	501
andrewbonney	0:ec559500a63f	502	snmp_inc_tcppassiveopens();
andrewbonney	0:ec559500a63f	503
andrewbonney	0:ec559500a63f	504	/* Send a SYN\|ACK together with the MSS option. */
andrewbonney	0:ec559500a63f	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
andrewbonney	0:ec559500a63f	506	if (rc != ERR_OK) {
andrewbonney	0:ec559500a63f	507	tcp_abandon(npcb, 0);
andrewbonney	0:ec559500a63f	508	return rc;
andrewbonney	0:ec559500a63f	509	}
andrewbonney	0:ec559500a63f	510	return tcp_output(npcb);
andrewbonney	0:ec559500a63f	511	}
andrewbonney	0:ec559500a63f	512	return ERR_OK;
andrewbonney	0:ec559500a63f	513	}
andrewbonney	0:ec559500a63f	514
andrewbonney	0:ec559500a63f	515	/**
andrewbonney	0:ec559500a63f	516	* Called by tcp_input() when a segment arrives for a connection in
andrewbonney	0:ec559500a63f	517	* TIME_WAIT.
andrewbonney	0:ec559500a63f	518	*
andrewbonney	0:ec559500a63f	519	* @param pcb the tcp_pcb for which a segment arrived
andrewbonney	0:ec559500a63f	520	*
andrewbonney	0:ec559500a63f	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
andrewbonney	0:ec559500a63f	522	* involved is passed as a parameter to this function
andrewbonney	0:ec559500a63f	523	*/
andrewbonney	0:ec559500a63f	524	static err_t
andrewbonney	0:ec559500a63f	525	tcp_timewait_input(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	526	{
andrewbonney	0:ec559500a63f	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
andrewbonney	0:ec559500a63f	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
andrewbonney	0:ec559500a63f	529	* - first check sequence number - we skip that one in TIME_WAIT (always
andrewbonney	0:ec559500a63f	530	* acceptable since we only send ACKs)
andrewbonney	0:ec559500a63f	531	* - second check the RST bit (... return) */
andrewbonney	0:ec559500a63f	532	if (flags & TCP_RST) {
andrewbonney	0:ec559500a63f	533	return ERR_OK;
andrewbonney	0:ec559500a63f	534	}
andrewbonney	0:ec559500a63f	535	/* - fourth, check the SYN bit, */
andrewbonney	0:ec559500a63f	536	if (flags & TCP_SYN) {
andrewbonney	0:ec559500a63f	537	/* If an incoming segment is not acceptable, an acknowledgment
andrewbonney	0:ec559500a63f	538	should be sent in reply */
andrewbonney	0:ec559500a63f	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
andrewbonney	0:ec559500a63f	540	/* If the SYN is in the window it is an error, send a reset */
andrewbonney	0:ec559500a63f	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:ec559500a63f	542	tcphdr->dest, tcphdr->src);
andrewbonney	0:ec559500a63f	543	return ERR_OK;
andrewbonney	0:ec559500a63f	544	}
andrewbonney	0:ec559500a63f	545	} else if (flags & TCP_FIN) {
andrewbonney	0:ec559500a63f	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
andrewbonney	0:ec559500a63f	547	Restart the 2 MSL time-wait timeout.*/
andrewbonney	0:ec559500a63f	548	pcb->tmr = tcp_ticks;
andrewbonney	0:ec559500a63f	549	}
andrewbonney	0:ec559500a63f	550
andrewbonney	0:ec559500a63f	551	if ((tcplen > 0)) {
andrewbonney	0:ec559500a63f	552	/* Acknowledge data, FIN or out-of-window SYN */
andrewbonney	0:ec559500a63f	553	pcb->flags \|= TF_ACK_NOW;
andrewbonney	0:ec559500a63f	554	return tcp_output(pcb);
andrewbonney	0:ec559500a63f	555	}
andrewbonney	0:ec559500a63f	556	return ERR_OK;
andrewbonney	0:ec559500a63f	557	}
andrewbonney	0:ec559500a63f	558
andrewbonney	0:ec559500a63f	559	/**
andrewbonney	0:ec559500a63f	560	* Implements the TCP state machine. Called by tcp_input. In some
andrewbonney	0:ec559500a63f	561	* states tcp_receive() is called to receive data. The tcp_seg
andrewbonney	0:ec559500a63f	562	* argument will be freed by the caller (tcp_input()) unless the
andrewbonney	0:ec559500a63f	563	* recv_data pointer in the pcb is set.
andrewbonney	0:ec559500a63f	564	*
andrewbonney	0:ec559500a63f	565	* @param pcb the tcp_pcb for which a segment arrived
andrewbonney	0:ec559500a63f	566	*
andrewbonney	0:ec559500a63f	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
andrewbonney	0:ec559500a63f	568	* involved is passed as a parameter to this function
andrewbonney	0:ec559500a63f	569	*/
andrewbonney	0:ec559500a63f	570	static err_t
andrewbonney	0:ec559500a63f	571	tcp_process(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	572	{
andrewbonney	0:ec559500a63f	573	struct tcp_seg *rseg;
andrewbonney	0:ec559500a63f	574	u8_t acceptable = 0;
andrewbonney	0:ec559500a63f	575	err_t err;
andrewbonney	0:ec559500a63f	576
andrewbonney	0:ec559500a63f	577	err = ERR_OK;
andrewbonney	0:ec559500a63f	578
andrewbonney	0:ec559500a63f	579	/* Process incoming RST segments. */
andrewbonney	0:ec559500a63f	580	if (flags & TCP_RST) {
andrewbonney	0:ec559500a63f	581	/* First, determine if the reset is acceptable. */
andrewbonney	0:ec559500a63f	582	if (pcb->state == SYN_SENT) {
andrewbonney	0:ec559500a63f	583	if (ackno == pcb->snd_nxt) {
andrewbonney	0:ec559500a63f	584	acceptable = 1;
andrewbonney	0:ec559500a63f	585	}
andrewbonney	0:ec559500a63f	586	} else {
andrewbonney	0:ec559500a63f	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
andrewbonney	0:ec559500a63f	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
andrewbonney	0:ec559500a63f	589	acceptable = 1;
andrewbonney	0:ec559500a63f	590	}
andrewbonney	0:ec559500a63f	591	}
andrewbonney	0:ec559500a63f	592
andrewbonney	0:ec559500a63f	593	if (acceptable) {
andrewbonney	0:ec559500a63f	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
andrewbonney	0:ec559500a63f	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
andrewbonney	0:ec559500a63f	596	recv_flags \|= TF_RESET;
andrewbonney	0:ec559500a63f	597	pcb->flags &= ~TF_ACK_DELAY;
andrewbonney	0:ec559500a63f	598	return ERR_RST;
andrewbonney	0:ec559500a63f	599	} else {
andrewbonney	0:ec559500a63f	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
andrewbonney	0:ec559500a63f	601	seqno, pcb->rcv_nxt));
andrewbonney	0:ec559500a63f	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
andrewbonney	0:ec559500a63f	603	seqno, pcb->rcv_nxt));
andrewbonney	0:ec559500a63f	604	return ERR_OK;
andrewbonney	0:ec559500a63f	605	}
andrewbonney	0:ec559500a63f	606	}
andrewbonney	0:ec559500a63f	607
andrewbonney	0:ec559500a63f	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
andrewbonney	0:ec559500a63f	609	/* Cope with new connection attempt after remote end crashed */
andrewbonney	0:ec559500a63f	610	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	611	return ERR_OK;
andrewbonney	0:ec559500a63f	612	}
andrewbonney	0:ec559500a63f	613
andrewbonney	0:ec559500a63f	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
andrewbonney	0:ec559500a63f	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
andrewbonney	0:ec559500a63f	616	pcb->tmr = tcp_ticks;
andrewbonney	0:ec559500a63f	617	}
andrewbonney	0:ec559500a63f	618	pcb->keep_cnt_sent = 0;
andrewbonney	0:ec559500a63f	619
andrewbonney	0:ec559500a63f	620	tcp_parseopt(pcb);
andrewbonney	0:ec559500a63f	621
andrewbonney	0:ec559500a63f	622	/* Do different things depending on the TCP state. */
andrewbonney	0:ec559500a63f	623	switch (pcb->state) {
andrewbonney	0:ec559500a63f	624	case SYN_SENT:
andrewbonney	0:ec559500a63f	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
andrewbonney	0:ec559500a63f	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
andrewbonney	0:ec559500a63f	627	/* received SYN ACK with expected sequence number? */
andrewbonney	0:ec559500a63f	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
andrewbonney	0:ec559500a63f	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
andrewbonney	0:ec559500a63f	630	pcb->snd_buf++;
andrewbonney	0:ec559500a63f	631	pcb->rcv_nxt = seqno + 1;
andrewbonney	0:ec559500a63f	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
andrewbonney	0:ec559500a63f	633	pcb->lastack = ackno;
andrewbonney	0:ec559500a63f	634	pcb->snd_wnd = tcphdr->wnd;
andrewbonney	0:ec559500a63f	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
andrewbonney	0:ec559500a63f	636	pcb->state = ESTABLISHED;
andrewbonney	0:ec559500a63f	637
andrewbonney	0:ec559500a63f	638	#if TCP_CALCULATE_EFF_SEND_MSS
andrewbonney	0:ec559500a63f	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
andrewbonney	0:ec559500a63f	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
andrewbonney	0:ec559500a63f	641
andrewbonney	0:ec559500a63f	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
andrewbonney	0:ec559500a63f	643	* but for the default value of pcb->mss) */
andrewbonney	0:ec559500a63f	644	pcb->ssthresh = pcb->mss * 10;
andrewbonney	0:ec559500a63f	645
andrewbonney	0:ec559500a63f	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
andrewbonney	0:ec559500a63f	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
andrewbonney	0:ec559500a63f	648	--pcb->snd_queuelen;
andrewbonney	0:ec559500a63f	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	650	rseg = pcb->unacked;
andrewbonney	0:ec559500a63f	651	pcb->unacked = rseg->next;
andrewbonney	0:ec559500a63f	652
andrewbonney	0:ec559500a63f	653	/* If there's nothing left to acknowledge, stop the retransmit
andrewbonney	0:ec559500a63f	654	timer, otherwise reset it to start again */
andrewbonney	0:ec559500a63f	655	if(pcb->unacked == NULL)
andrewbonney	0:ec559500a63f	656	pcb->rtime = -1;
andrewbonney	0:ec559500a63f	657	else {
andrewbonney	0:ec559500a63f	658	pcb->rtime = 0;
andrewbonney	0:ec559500a63f	659	pcb->nrtx = 0;
andrewbonney	0:ec559500a63f	660	}
andrewbonney	0:ec559500a63f	661
andrewbonney	0:ec559500a63f	662	tcp_seg_free(rseg);
andrewbonney	0:ec559500a63f	663
andrewbonney	0:ec559500a63f	664	/* Call the user specified function to call when sucessfully
andrewbonney	0:ec559500a63f	665	* connected. */
andrewbonney	0:ec559500a63f	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
andrewbonney	0:ec559500a63f	667	if (err == ERR_ABRT) {
andrewbonney	0:ec559500a63f	668	return ERR_ABRT;
andrewbonney	0:ec559500a63f	669	}
andrewbonney	0:ec559500a63f	670	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	671	}
andrewbonney	0:ec559500a63f	672	/* received ACK? possibly a half-open connection */
andrewbonney	0:ec559500a63f	673	else if (flags & TCP_ACK) {
andrewbonney	0:ec559500a63f	674	/* send a RST to bring the other side in a non-synchronized state. */
andrewbonney	0:ec559500a63f	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:ec559500a63f	676	tcphdr->dest, tcphdr->src);
andrewbonney	0:ec559500a63f	677	}
andrewbonney	0:ec559500a63f	678	break;
andrewbonney	0:ec559500a63f	679	case SYN_RCVD:
andrewbonney	0:ec559500a63f	680	if (flags & TCP_ACK) {
andrewbonney	0:ec559500a63f	681	/* expected ACK number? */
andrewbonney	0:ec559500a63f	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
andrewbonney	0:ec559500a63f	683	u16_t old_cwnd;
andrewbonney	0:ec559500a63f	684	pcb->state = ESTABLISHED;
andrewbonney	0:ec559500a63f	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:ec559500a63f	686	#if LWIP_CALLBACK_API
andrewbonney	0:ec559500a63f	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
andrewbonney	0:ec559500a63f	688	#endif
andrewbonney	0:ec559500a63f	689	/* Call the accept function. */
andrewbonney	0:ec559500a63f	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
andrewbonney	0:ec559500a63f	691	if (err != ERR_OK) {
andrewbonney	0:ec559500a63f	692	/* If the accept function returns with an error, we abort
andrewbonney	0:ec559500a63f	693	* the connection. */
andrewbonney	0:ec559500a63f	694	/* Already aborted? */
andrewbonney	0:ec559500a63f	695	if (err != ERR_ABRT) {
andrewbonney	0:ec559500a63f	696	tcp_abort(pcb);
andrewbonney	0:ec559500a63f	697	}
andrewbonney	0:ec559500a63f	698	return ERR_ABRT;
andrewbonney	0:ec559500a63f	699	}
andrewbonney	0:ec559500a63f	700	old_cwnd = pcb->cwnd;
andrewbonney	0:ec559500a63f	701	/* If there was any data contained within this ACK,
andrewbonney	0:ec559500a63f	702	* we'd better pass it on to the application as well. */
andrewbonney	0:ec559500a63f	703	tcp_receive(pcb);
andrewbonney	0:ec559500a63f	704
andrewbonney	0:ec559500a63f	705	/* Prevent ACK for SYN to generate a sent event */
andrewbonney	0:ec559500a63f	706	if (pcb->acked != 0) {
andrewbonney	0:ec559500a63f	707	pcb->acked--;
andrewbonney	0:ec559500a63f	708	}
andrewbonney	0:ec559500a63f	709
andrewbonney	0:ec559500a63f	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
andrewbonney	0:ec559500a63f	711
andrewbonney	0:ec559500a63f	712	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:ec559500a63f	713	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	714	pcb->state = CLOSE_WAIT;
andrewbonney	0:ec559500a63f	715	}
andrewbonney	0:ec559500a63f	716	} else {
andrewbonney	0:ec559500a63f	717	/* incorrect ACK number, send RST */
andrewbonney	0:ec559500a63f	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:ec559500a63f	719	tcphdr->dest, tcphdr->src);
andrewbonney	0:ec559500a63f	720	}
andrewbonney	0:ec559500a63f	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
andrewbonney	0:ec559500a63f	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
andrewbonney	0:ec559500a63f	723	tcp_rexmit(pcb);
andrewbonney	0:ec559500a63f	724	}
andrewbonney	0:ec559500a63f	725	break;
andrewbonney	0:ec559500a63f	726	case CLOSE_WAIT:
andrewbonney	0:ec559500a63f	727	/* FALLTHROUGH */
andrewbonney	0:ec559500a63f	728	case ESTABLISHED:
andrewbonney	0:ec559500a63f	729	tcp_receive(pcb);
andrewbonney	0:ec559500a63f	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
andrewbonney	0:ec559500a63f	731	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	732	pcb->state = CLOSE_WAIT;
andrewbonney	0:ec559500a63f	733	}
andrewbonney	0:ec559500a63f	734	break;
andrewbonney	0:ec559500a63f	735	case FIN_WAIT_1:
andrewbonney	0:ec559500a63f	736	tcp_receive(pcb);
andrewbonney	0:ec559500a63f	737	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:ec559500a63f	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
andrewbonney	0:ec559500a63f	739	LWIP_DEBUGF(TCP_DEBUG,
andrewbonney	0:ec559500a63f	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:ec559500a63f	741	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	742	tcp_pcb_purge(pcb);
andrewbonney	0:ec559500a63f	743	TCP_RMV(&tcp_active_pcbs, pcb);
andrewbonney	0:ec559500a63f	744	pcb->state = TIME_WAIT;
andrewbonney	0:ec559500a63f	745	TCP_REG(&tcp_tw_pcbs, pcb);
andrewbonney	0:ec559500a63f	746	} else {
andrewbonney	0:ec559500a63f	747	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	748	pcb->state = CLOSING;
andrewbonney	0:ec559500a63f	749	}
andrewbonney	0:ec559500a63f	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
andrewbonney	0:ec559500a63f	751	pcb->state = FIN_WAIT_2;
andrewbonney	0:ec559500a63f	752	}
andrewbonney	0:ec559500a63f	753	break;
andrewbonney	0:ec559500a63f	754	case FIN_WAIT_2:
andrewbonney	0:ec559500a63f	755	tcp_receive(pcb);
andrewbonney	0:ec559500a63f	756	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:ec559500a63f	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:ec559500a63f	758	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	759	tcp_pcb_purge(pcb);
andrewbonney	0:ec559500a63f	760	TCP_RMV(&tcp_active_pcbs, pcb);
andrewbonney	0:ec559500a63f	761	pcb->state = TIME_WAIT;
andrewbonney	0:ec559500a63f	762	TCP_REG(&tcp_tw_pcbs, pcb);
andrewbonney	0:ec559500a63f	763	}
andrewbonney	0:ec559500a63f	764	break;
andrewbonney	0:ec559500a63f	765	case CLOSING:
andrewbonney	0:ec559500a63f	766	tcp_receive(pcb);
andrewbonney	0:ec559500a63f	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
andrewbonney	0:ec559500a63f	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:ec559500a63f	769	tcp_pcb_purge(pcb);
andrewbonney	0:ec559500a63f	770	TCP_RMV(&tcp_active_pcbs, pcb);
andrewbonney	0:ec559500a63f	771	pcb->state = TIME_WAIT;
andrewbonney	0:ec559500a63f	772	TCP_REG(&tcp_tw_pcbs, pcb);
andrewbonney	0:ec559500a63f	773	}
andrewbonney	0:ec559500a63f	774	break;
andrewbonney	0:ec559500a63f	775	case LAST_ACK:
andrewbonney	0:ec559500a63f	776	tcp_receive(pcb);
andrewbonney	0:ec559500a63f	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
andrewbonney	0:ec559500a63f	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:ec559500a63f	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
andrewbonney	0:ec559500a63f	780	recv_flags \|= TF_CLOSED;
andrewbonney	0:ec559500a63f	781	}
andrewbonney	0:ec559500a63f	782	break;
andrewbonney	0:ec559500a63f	783	default:
andrewbonney	0:ec559500a63f	784	break;
andrewbonney	0:ec559500a63f	785	}
andrewbonney	0:ec559500a63f	786	return ERR_OK;
andrewbonney	0:ec559500a63f	787	}
andrewbonney	0:ec559500a63f	788
andrewbonney	0:ec559500a63f	789	#if TCP_QUEUE_OOSEQ
andrewbonney	0:ec559500a63f	790	/**
andrewbonney	0:ec559500a63f	791	* Insert segment into the list (segments covered with new one will be deleted)
andrewbonney	0:ec559500a63f	792	*
andrewbonney	0:ec559500a63f	793	* Called from tcp_receive()
andrewbonney	0:ec559500a63f	794	*/
andrewbonney	0:ec559500a63f	795	static void
andrewbonney	0:ec559500a63f	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
andrewbonney	0:ec559500a63f	797	{
andrewbonney	0:ec559500a63f	798	struct tcp_seg *old_seg;
andrewbonney	0:ec559500a63f	799
andrewbonney	0:ec559500a63f	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	801	/* received segment overlaps all following segments */
andrewbonney	0:ec559500a63f	802	tcp_segs_free(next);
andrewbonney	0:ec559500a63f	803	next = NULL;
andrewbonney	0:ec559500a63f	804	}
andrewbonney	0:ec559500a63f	805	else {
andrewbonney	0:ec559500a63f	806	/* delete some following segments
andrewbonney	0:ec559500a63f	807	oos queue may have segments with FIN flag */
andrewbonney	0:ec559500a63f	808	while (next &&
andrewbonney	0:ec559500a63f	809	TCP_SEQ_GEQ((seqno + cseg->len),
andrewbonney	0:ec559500a63f	810	(next->tcphdr->seqno + next->len))) {
andrewbonney	0:ec559500a63f	811	/* cseg with FIN already processed */
andrewbonney	0:ec559500a63f	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
andrewbonney	0:ec559500a63f	814	}
andrewbonney	0:ec559500a63f	815	old_seg = next;
andrewbonney	0:ec559500a63f	816	next = next->next;
andrewbonney	0:ec559500a63f	817	tcp_seg_free(old_seg);
andrewbonney	0:ec559500a63f	818	}
andrewbonney	0:ec559500a63f	819	if (next &&
andrewbonney	0:ec559500a63f	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
andrewbonney	0:ec559500a63f	821	/* We need to trim the incoming segment. */
andrewbonney	0:ec559500a63f	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
andrewbonney	0:ec559500a63f	823	pbuf_realloc(cseg->p, cseg->len);
andrewbonney	0:ec559500a63f	824	}
andrewbonney	0:ec559500a63f	825	}
andrewbonney	0:ec559500a63f	826	cseg->next = next;
andrewbonney	0:ec559500a63f	827	}
andrewbonney	0:ec559500a63f	828	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:ec559500a63f	829
andrewbonney	0:ec559500a63f	830	/**
andrewbonney	0:ec559500a63f	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
andrewbonney	0:ec559500a63f	832	* data, and if so frees the memory of the buffered data. Next, is places the
andrewbonney	0:ec559500a63f	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
andrewbonney	0:ec559500a63f	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
andrewbonney	0:ec559500a63f	835	* i it has been removed from the buffer.
andrewbonney	0:ec559500a63f	836	*
andrewbonney	0:ec559500a63f	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
andrewbonney	0:ec559500a63f	838	* estimation, the RTT is estimated here as well.
andrewbonney	0:ec559500a63f	839	*
andrewbonney	0:ec559500a63f	840	* Called from tcp_process().
andrewbonney	0:ec559500a63f	841	*/
andrewbonney	0:ec559500a63f	842	static void
andrewbonney	0:ec559500a63f	843	tcp_receive(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	844	{
andrewbonney	0:ec559500a63f	845	struct tcp_seg *next;
andrewbonney	0:ec559500a63f	846	#if TCP_QUEUE_OOSEQ
andrewbonney	0:ec559500a63f	847	struct tcp_seg prev, cseg;
andrewbonney	0:ec559500a63f	848	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:ec559500a63f	849	struct pbuf *p;
andrewbonney	0:ec559500a63f	850	s32_t off;
andrewbonney	0:ec559500a63f	851	s16_t m;
andrewbonney	0:ec559500a63f	852	u32_t right_wnd_edge;
andrewbonney	0:ec559500a63f	853	u16_t new_tot_len;
andrewbonney	0:ec559500a63f	854	int found_dupack = 0;
andrewbonney	0:ec559500a63f	855
andrewbonney	0:ec559500a63f	856	if (flags & TCP_ACK) {
andrewbonney	0:ec559500a63f	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
andrewbonney	0:ec559500a63f	858
andrewbonney	0:ec559500a63f	859	/* Update window. */
andrewbonney	0:ec559500a63f	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
andrewbonney	0:ec559500a63f	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
andrewbonney	0:ec559500a63f	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
andrewbonney	0:ec559500a63f	863	pcb->snd_wnd = tcphdr->wnd;
andrewbonney	0:ec559500a63f	864	pcb->snd_wl1 = seqno;
andrewbonney	0:ec559500a63f	865	pcb->snd_wl2 = ackno;
andrewbonney	0:ec559500a63f	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
andrewbonney	0:ec559500a63f	867	pcb->persist_backoff = 0;
andrewbonney	0:ec559500a63f	868	}
andrewbonney	0:ec559500a63f	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
andrewbonney	0:ec559500a63f	870	#if TCP_WND_DEBUG
andrewbonney	0:ec559500a63f	871	} else {
andrewbonney	0:ec559500a63f	872	if (pcb->snd_wnd != tcphdr->wnd) {
andrewbonney	0:ec559500a63f	873	LWIP_DEBUGF(TCP_WND_DEBUG,
andrewbonney	0:ec559500a63f	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
andrewbonney	0:ec559500a63f	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
andrewbonney	0:ec559500a63f	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
andrewbonney	0:ec559500a63f	877	}
andrewbonney	0:ec559500a63f	878	#endif /* TCP_WND_DEBUG */
andrewbonney	0:ec559500a63f	879	}
andrewbonney	0:ec559500a63f	880
andrewbonney	0:ec559500a63f	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
andrewbonney	0:ec559500a63f	882	* duplicate ack if:
andrewbonney	0:ec559500a63f	883	* 1) It doesn't ACK new data
andrewbonney	0:ec559500a63f	884	* 2) length of received packet is zero (i.e. no payload)
andrewbonney	0:ec559500a63f	885	* 3) the advertised window hasn't changed
andrewbonney	0:ec559500a63f	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
andrewbonney	0:ec559500a63f	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
andrewbonney	0:ec559500a63f	888	*
andrewbonney	0:ec559500a63f	889	* If it passes all five, should process as a dupack:
andrewbonney	0:ec559500a63f	890	* a) dupacks < 3: do nothing
andrewbonney	0:ec559500a63f	891	* b) dupacks == 3: fast retransmit
andrewbonney	0:ec559500a63f	892	* c) dupacks > 3: increase cwnd
andrewbonney	0:ec559500a63f	893	*
andrewbonney	0:ec559500a63f	894	* If it only passes 1-3, should reset dupack counter (and add to
andrewbonney	0:ec559500a63f	895	* stats, which we don't do in lwIP)
andrewbonney	0:ec559500a63f	896	*
andrewbonney	0:ec559500a63f	897	* If it only passes 1, should reset dupack counter
andrewbonney	0:ec559500a63f	898	*
andrewbonney	0:ec559500a63f	899	*/
andrewbonney	0:ec559500a63f	900
andrewbonney	0:ec559500a63f	901	/* Clause 1 */
andrewbonney	0:ec559500a63f	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
andrewbonney	0:ec559500a63f	903	pcb->acked = 0;
andrewbonney	0:ec559500a63f	904	/* Clause 2 */
andrewbonney	0:ec559500a63f	905	if (tcplen == 0) {
andrewbonney	0:ec559500a63f	906	/* Clause 3 */
andrewbonney	0:ec559500a63f	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
andrewbonney	0:ec559500a63f	908	/* Clause 4 */
andrewbonney	0:ec559500a63f	909	if (pcb->rtime >= 0) {
andrewbonney	0:ec559500a63f	910	/* Clause 5 */
andrewbonney	0:ec559500a63f	911	if (pcb->lastack == ackno) {
andrewbonney	0:ec559500a63f	912	found_dupack = 1;
andrewbonney	0:ec559500a63f	913	if (pcb->dupacks + 1 > pcb->dupacks)
andrewbonney	0:ec559500a63f	914	++pcb->dupacks;
andrewbonney	0:ec559500a63f	915	if (pcb->dupacks > 3) {
andrewbonney	0:ec559500a63f	916	/* Inflate the congestion window, but not if it means that
andrewbonney	0:ec559500a63f	917	the value overflows. */
andrewbonney	0:ec559500a63f	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
andrewbonney	0:ec559500a63f	919	pcb->cwnd += pcb->mss;
andrewbonney	0:ec559500a63f	920	}
andrewbonney	0:ec559500a63f	921	} else if (pcb->dupacks == 3) {
andrewbonney	0:ec559500a63f	922	/* Do fast retransmit */
andrewbonney	0:ec559500a63f	923	tcp_rexmit_fast(pcb);
andrewbonney	0:ec559500a63f	924	}
andrewbonney	0:ec559500a63f	925	}
andrewbonney	0:ec559500a63f	926	}
andrewbonney	0:ec559500a63f	927	}
andrewbonney	0:ec559500a63f	928	}
andrewbonney	0:ec559500a63f	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
andrewbonney	0:ec559500a63f	930	* count of consecutive duplicate acks */
andrewbonney	0:ec559500a63f	931	if (!found_dupack) {
andrewbonney	0:ec559500a63f	932	pcb->dupacks = 0;
andrewbonney	0:ec559500a63f	933	}
andrewbonney	0:ec559500a63f	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
andrewbonney	0:ec559500a63f	935	/* We come here when the ACK acknowledges new data. */
andrewbonney	0:ec559500a63f	936
andrewbonney	0:ec559500a63f	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
andrewbonney	0:ec559500a63f	938	in fast retransmit. Also reset the congestion window to the
andrewbonney	0:ec559500a63f	939	slow start threshold. */
andrewbonney	0:ec559500a63f	940	if (pcb->flags & TF_INFR) {
andrewbonney	0:ec559500a63f	941	pcb->flags &= ~TF_INFR;
andrewbonney	0:ec559500a63f	942	pcb->cwnd = pcb->ssthresh;
andrewbonney	0:ec559500a63f	943	}
andrewbonney	0:ec559500a63f	944
andrewbonney	0:ec559500a63f	945	/* Reset the number of retransmissions. */
andrewbonney	0:ec559500a63f	946	pcb->nrtx = 0;
andrewbonney	0:ec559500a63f	947
andrewbonney	0:ec559500a63f	948	/* Reset the retransmission time-out. */
andrewbonney	0:ec559500a63f	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
andrewbonney	0:ec559500a63f	950
andrewbonney	0:ec559500a63f	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
andrewbonney	0:ec559500a63f	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
andrewbonney	0:ec559500a63f	953
andrewbonney	0:ec559500a63f	954	pcb->snd_buf += pcb->acked;
andrewbonney	0:ec559500a63f	955
andrewbonney	0:ec559500a63f	956	/* Reset the fast retransmit variables. */
andrewbonney	0:ec559500a63f	957	pcb->dupacks = 0;
andrewbonney	0:ec559500a63f	958	pcb->lastack = ackno;
andrewbonney	0:ec559500a63f	959
andrewbonney	0:ec559500a63f	960	/* Update the congestion control variables (cwnd and
andrewbonney	0:ec559500a63f	961	ssthresh). */
andrewbonney	0:ec559500a63f	962	if (pcb->state >= ESTABLISHED) {
andrewbonney	0:ec559500a63f	963	if (pcb->cwnd < pcb->ssthresh) {
andrewbonney	0:ec559500a63f	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
andrewbonney	0:ec559500a63f	965	pcb->cwnd += pcb->mss;
andrewbonney	0:ec559500a63f	966	}
andrewbonney	0:ec559500a63f	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
andrewbonney	0:ec559500a63f	968	} else {
andrewbonney	0:ec559500a63f	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
andrewbonney	0:ec559500a63f	970	if (new_cwnd > pcb->cwnd) {
andrewbonney	0:ec559500a63f	971	pcb->cwnd = new_cwnd;
andrewbonney	0:ec559500a63f	972	}
andrewbonney	0:ec559500a63f	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
andrewbonney	0:ec559500a63f	974	}
andrewbonney	0:ec559500a63f	975	}
andrewbonney	0:ec559500a63f	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
andrewbonney	0:ec559500a63f	977	ackno,
andrewbonney	0:ec559500a63f	978	pcb->unacked != NULL?
andrewbonney	0:ec559500a63f	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
andrewbonney	0:ec559500a63f	980	pcb->unacked != NULL?
andrewbonney	0:ec559500a63f	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
andrewbonney	0:ec559500a63f	982
andrewbonney	0:ec559500a63f	983	/* Remove segment from the unacknowledged list if the incoming
andrewbonney	0:ec559500a63f	984	ACK acknowlegdes them. */
andrewbonney	0:ec559500a63f	985	while (pcb->unacked != NULL &&
andrewbonney	0:ec559500a63f	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
andrewbonney	0:ec559500a63f	987	TCP_TCPLEN(pcb->unacked), ackno)) {
andrewbonney	0:ec559500a63f	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
andrewbonney	0:ec559500a63f	989	ntohl(pcb->unacked->tcphdr->seqno),
andrewbonney	0:ec559500a63f	990	ntohl(pcb->unacked->tcphdr->seqno) +
andrewbonney	0:ec559500a63f	991	TCP_TCPLEN(pcb->unacked)));
andrewbonney	0:ec559500a63f	992
andrewbonney	0:ec559500a63f	993	next = pcb->unacked;
andrewbonney	0:ec559500a63f	994	pcb->unacked = pcb->unacked->next;
andrewbonney	0:ec559500a63f	995
andrewbonney	0:ec559500a63f	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
andrewbonney	0:ec559500a63f	998	/* Prevent ACK for FIN to generate a sent event */
andrewbonney	0:ec559500a63f	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
andrewbonney	0:ec559500a63f	1000	pcb->acked--;
andrewbonney	0:ec559500a63f	1001	}
andrewbonney	0:ec559500a63f	1002
andrewbonney	0:ec559500a63f	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
andrewbonney	0:ec559500a63f	1004	tcp_seg_free(next);
andrewbonney	0:ec559500a63f	1005
andrewbonney	0:ec559500a63f	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	1007	if (pcb->snd_queuelen != 0) {
andrewbonney	0:ec559500a63f	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
andrewbonney	0:ec559500a63f	1009	pcb->unsent != NULL);
andrewbonney	0:ec559500a63f	1010	}
andrewbonney	0:ec559500a63f	1011	}
andrewbonney	0:ec559500a63f	1012
andrewbonney	0:ec559500a63f	1013	/* If there's nothing left to acknowledge, stop the retransmit
andrewbonney	0:ec559500a63f	1014	timer, otherwise reset it to start again */
andrewbonney	0:ec559500a63f	1015	if(pcb->unacked == NULL)
andrewbonney	0:ec559500a63f	1016	pcb->rtime = -1;
andrewbonney	0:ec559500a63f	1017	else
andrewbonney	0:ec559500a63f	1018	pcb->rtime = 0;
andrewbonney	0:ec559500a63f	1019
andrewbonney	0:ec559500a63f	1020	pcb->polltmr = 0;
andrewbonney	0:ec559500a63f	1021	} else {
andrewbonney	0:ec559500a63f	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
andrewbonney	0:ec559500a63f	1023	pcb->acked = 0;
andrewbonney	0:ec559500a63f	1024	}
andrewbonney	0:ec559500a63f	1025
andrewbonney	0:ec559500a63f	1026	/* We go through the ->unsent list to see if any of the segments
andrewbonney	0:ec559500a63f	1027	on the list are acknowledged by the ACK. This may seem
andrewbonney	0:ec559500a63f	1028	strange since an "unsent" segment shouldn't be acked. The
andrewbonney	0:ec559500a63f	1029	rationale is that lwIP puts all outstanding segments on the
andrewbonney	0:ec559500a63f	1030	->unsent list after a retransmission, so these segments may
andrewbonney	0:ec559500a63f	1031	in fact have been sent once. */
andrewbonney	0:ec559500a63f	1032	while (pcb->unsent != NULL &&
andrewbonney	0:ec559500a63f	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
andrewbonney	0:ec559500a63f	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
andrewbonney	0:ec559500a63f	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
andrewbonney	0:ec559500a63f	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
andrewbonney	0:ec559500a63f	1037	TCP_TCPLEN(pcb->unsent)));
andrewbonney	0:ec559500a63f	1038
andrewbonney	0:ec559500a63f	1039	next = pcb->unsent;
andrewbonney	0:ec559500a63f	1040	pcb->unsent = pcb->unsent->next;
andrewbonney	0:ec559500a63f	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
andrewbonney	0:ec559500a63f	1043	/* Prevent ACK for FIN to generate a sent event */
andrewbonney	0:ec559500a63f	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
andrewbonney	0:ec559500a63f	1045	pcb->acked--;
andrewbonney	0:ec559500a63f	1046	}
andrewbonney	0:ec559500a63f	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
andrewbonney	0:ec559500a63f	1048	tcp_seg_free(next);
andrewbonney	0:ec559500a63f	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:ec559500a63f	1050	if (pcb->snd_queuelen != 0) {
andrewbonney	0:ec559500a63f	1051	LWIP_ASSERT("tcp_receive: valid queue length",
andrewbonney	0:ec559500a63f	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
andrewbonney	0:ec559500a63f	1053	}
andrewbonney	0:ec559500a63f	1054	}
andrewbonney	0:ec559500a63f	1055	/* End of ACK for new data processing. */
andrewbonney	0:ec559500a63f	1056
andrewbonney	0:ec559500a63f	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
andrewbonney	0:ec559500a63f	1058	pcb->rttest, pcb->rtseq, ackno));
andrewbonney	0:ec559500a63f	1059
andrewbonney	0:ec559500a63f	1060	/* RTT estimation calculations. This is done by checking if the
andrewbonney	0:ec559500a63f	1061	incoming segment acknowledges the segment we use to take a
andrewbonney	0:ec559500a63f	1062	round-trip time measurement. */
andrewbonney	0:ec559500a63f	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
andrewbonney	0:ec559500a63f	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
andrewbonney	0:ec559500a63f	1065	and a round-trip shouldn't be that long... */
andrewbonney	0:ec559500a63f	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
andrewbonney	0:ec559500a63f	1067
andrewbonney	0:ec559500a63f	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
andrewbonney	0:ec559500a63f	1069	m, m * TCP_SLOW_INTERVAL));
andrewbonney	0:ec559500a63f	1070
andrewbonney	0:ec559500a63f	1071	/* This is taken directly from VJs original code in his paper */
andrewbonney	0:ec559500a63f	1072	m = m - (pcb->sa >> 3);
andrewbonney	0:ec559500a63f	1073	pcb->sa += m;
andrewbonney	0:ec559500a63f	1074	if (m < 0) {
andrewbonney	0:ec559500a63f	1075	m = -m;
andrewbonney	0:ec559500a63f	1076	}
andrewbonney	0:ec559500a63f	1077	m = m - (pcb->sv >> 2);
andrewbonney	0:ec559500a63f	1078	pcb->sv += m;
andrewbonney	0:ec559500a63f	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
andrewbonney	0:ec559500a63f	1080
andrewbonney	0:ec559500a63f	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
andrewbonney	0:ec559500a63f	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
andrewbonney	0:ec559500a63f	1083
andrewbonney	0:ec559500a63f	1084	pcb->rttest = 0;
andrewbonney	0:ec559500a63f	1085	}
andrewbonney	0:ec559500a63f	1086	}
andrewbonney	0:ec559500a63f	1087
andrewbonney	0:ec559500a63f	1088	/* If the incoming segment contains data, we must process it
andrewbonney	0:ec559500a63f	1089	further. */
andrewbonney	0:ec559500a63f	1090	if (tcplen > 0) {
andrewbonney	0:ec559500a63f	1091	/* This code basically does three things:
andrewbonney	0:ec559500a63f	1092
andrewbonney	0:ec559500a63f	1093	+) If the incoming segment contains data that is the next
andrewbonney	0:ec559500a63f	1094	in-sequence data, this data is passed to the application. This
andrewbonney	0:ec559500a63f	1095	might involve trimming the first edge of the data. The rcv_nxt
andrewbonney	0:ec559500a63f	1096	variable and the advertised window are adjusted.
andrewbonney	0:ec559500a63f	1097
andrewbonney	0:ec559500a63f	1098	+) If the incoming segment has data that is above the next
andrewbonney	0:ec559500a63f	1099	sequence number expected (->rcv_nxt), the segment is placed on
andrewbonney	0:ec559500a63f	1100	the ->ooseq queue. This is done by finding the appropriate
andrewbonney	0:ec559500a63f	1101	place in the ->ooseq queue (which is ordered by sequence
andrewbonney	0:ec559500a63f	1102	number) and trim the segment in both ends if needed. An
andrewbonney	0:ec559500a63f	1103	immediate ACK is sent to indicate that we received an
andrewbonney	0:ec559500a63f	1104	out-of-sequence segment.
andrewbonney	0:ec559500a63f	1105
andrewbonney	0:ec559500a63f	1106	+) Finally, we check if the first segment on the ->ooseq queue
andrewbonney	0:ec559500a63f	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
andrewbonney	0:ec559500a63f	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
andrewbonney	0:ec559500a63f	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
andrewbonney	0:ec559500a63f	1110	segments that are now on sequence are chained onto the
andrewbonney	0:ec559500a63f	1111	incoming segment so that we only need to call the application
andrewbonney	0:ec559500a63f	1112	once.
andrewbonney	0:ec559500a63f	1113	*/
andrewbonney	0:ec559500a63f	1114
andrewbonney	0:ec559500a63f	1115	/* First, we check if we must trim the first edge. We have to do
andrewbonney	0:ec559500a63f	1116	this if the sequence number of the incoming segment is less
andrewbonney	0:ec559500a63f	1117	than rcv_nxt, and the sequence number plus the length of the
andrewbonney	0:ec559500a63f	1118	segment is larger than rcv_nxt. */
andrewbonney	0:ec559500a63f	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
andrewbonney	0:ec559500a63f	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
andrewbonney	0:ec559500a63f	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
andrewbonney	0:ec559500a63f	1122	/* Trimming the first edge is done by pushing the payload
andrewbonney	0:ec559500a63f	1123	pointer in the pbuf downwards. This is somewhat tricky since
andrewbonney	0:ec559500a63f	1124	we do not want to discard the full contents of the pbuf up to
andrewbonney	0:ec559500a63f	1125	the new starting point of the data since we have to keep the
andrewbonney	0:ec559500a63f	1126	TCP header which is present in the first pbuf in the chain.
andrewbonney	0:ec559500a63f	1127
andrewbonney	0:ec559500a63f	1128	What is done is really quite a nasty hack: the first pbuf in
andrewbonney	0:ec559500a63f	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
andrewbonney	0:ec559500a63f	1130	able to deallocate the whole pbuf, we cannot change this
andrewbonney	0:ec559500a63f	1131	inseg.p pointer to point to any of the later pbufs in the
andrewbonney	0:ec559500a63f	1132	chain. Instead, we point the ->payload pointer in the first
andrewbonney	0:ec559500a63f	1133	pbuf to data in one of the later pbufs. We also set the
andrewbonney	0:ec559500a63f	1134	inseg.data pointer to point to the right place. This way, the
andrewbonney	0:ec559500a63f	1135	->p pointer will still point to the first pbuf, but the
andrewbonney	0:ec559500a63f	1136	->p->payload pointer will point to data in another pbuf.
andrewbonney	0:ec559500a63f	1137
andrewbonney	0:ec559500a63f	1138	After we are done with adjusting the pbuf pointers we must
andrewbonney	0:ec559500a63f	1139	adjust the ->data pointer in the seg and the segment
andrewbonney	0:ec559500a63f	1140	length.*/
andrewbonney	0:ec559500a63f	1141
andrewbonney	0:ec559500a63f	1142	off = pcb->rcv_nxt - seqno;
andrewbonney	0:ec559500a63f	1143	p = inseg.p;
andrewbonney	0:ec559500a63f	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
andrewbonney	0:ec559500a63f	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
andrewbonney	0:ec559500a63f	1146	if (inseg.p->len < off) {
andrewbonney	0:ec559500a63f	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
andrewbonney	0:ec559500a63f	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
andrewbonney	0:ec559500a63f	1149	while (p->len < off) {
andrewbonney	0:ec559500a63f	1150	off -= p->len;
andrewbonney	0:ec559500a63f	1151	/* KJM following line changed (with addition of new_tot_len var)
andrewbonney	0:ec559500a63f	1152	to fix bug #9076
andrewbonney	0:ec559500a63f	1153	inseg.p->tot_len -= p->len; */
andrewbonney	0:ec559500a63f	1154	p->tot_len = new_tot_len;
andrewbonney	0:ec559500a63f	1155	p->len = 0;
andrewbonney	0:ec559500a63f	1156	p = p->next;
andrewbonney	0:ec559500a63f	1157	}
andrewbonney	0:ec559500a63f	1158	if(pbuf_header(p, (s16_t)-off)) {
andrewbonney	0:ec559500a63f	1159	/* Do we need to cope with this failing? Assert for now */
andrewbonney	0:ec559500a63f	1160	LWIP_ASSERT("pbuf_header failed", 0);
andrewbonney	0:ec559500a63f	1161	}
andrewbonney	0:ec559500a63f	1162	} else {
andrewbonney	0:ec559500a63f	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
andrewbonney	0:ec559500a63f	1164	/* Do we need to cope with this failing? Assert for now */
andrewbonney	0:ec559500a63f	1165	LWIP_ASSERT("pbuf_header failed", 0);
andrewbonney	0:ec559500a63f	1166	}
andrewbonney	0:ec559500a63f	1167	}
andrewbonney	0:ec559500a63f	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
andrewbonney	0:ec559500a63f	1169	to fix bug #9076 */
andrewbonney	0:ec559500a63f	1170	inseg.dataptr = p->payload;
andrewbonney	0:ec559500a63f	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
andrewbonney	0:ec559500a63f	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
andrewbonney	0:ec559500a63f	1173	}
andrewbonney	0:ec559500a63f	1174	else {
andrewbonney	0:ec559500a63f	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
andrewbonney	0:ec559500a63f	1176	/* the whole segment is < rcv_nxt */
andrewbonney	0:ec559500a63f	1177	/* must be a duplicate of a packet that has already been correctly handled */
andrewbonney	0:ec559500a63f	1178
andrewbonney	0:ec559500a63f	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
andrewbonney	0:ec559500a63f	1180	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	1181	}
andrewbonney	0:ec559500a63f	1182	}
andrewbonney	0:ec559500a63f	1183
andrewbonney	0:ec559500a63f	1184	/* The sequence number must be within the window (above rcv_nxt
andrewbonney	0:ec559500a63f	1185	and below rcv_nxt + rcv_wnd) in order to be further
andrewbonney	0:ec559500a63f	1186	processed. */
andrewbonney	0:ec559500a63f	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
andrewbonney	0:ec559500a63f	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
andrewbonney	0:ec559500a63f	1189	if (pcb->rcv_nxt == seqno) {
andrewbonney	0:ec559500a63f	1190	/* The incoming segment is the next in sequence. We check if
andrewbonney	0:ec559500a63f	1191	we have to trim the end of the segment and update rcv_nxt
andrewbonney	0:ec559500a63f	1192	and pass the data to the application. */
andrewbonney	0:ec559500a63f	1193	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:ec559500a63f	1194
andrewbonney	0:ec559500a63f	1195	if (tcplen > pcb->rcv_wnd) {
andrewbonney	0:ec559500a63f	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
andrewbonney	0:ec559500a63f	1197	("tcp_receive: other end overran receive window"
andrewbonney	0:ec559500a63f	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
andrewbonney	0:ec559500a63f	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:ec559500a63f	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	1201	/* Must remove the FIN from the header as we're trimming
andrewbonney	0:ec559500a63f	1202	* that byte of sequence-space from the packet */
andrewbonney	0:ec559500a63f	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
andrewbonney	0:ec559500a63f	1204	}
andrewbonney	0:ec559500a63f	1205	/* Adjust length of segment to fit in the window. */
andrewbonney	0:ec559500a63f	1206	inseg.len = pcb->rcv_wnd;
andrewbonney	0:ec559500a63f	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
andrewbonney	0:ec559500a63f	1208	inseg.len -= 1;
andrewbonney	0:ec559500a63f	1209	}
andrewbonney	0:ec559500a63f	1210	pbuf_realloc(inseg.p, inseg.len);
andrewbonney	0:ec559500a63f	1211	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:ec559500a63f	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
andrewbonney	0:ec559500a63f	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:ec559500a63f	1214	}
andrewbonney	0:ec559500a63f	1215	#if TCP_QUEUE_OOSEQ
andrewbonney	0:ec559500a63f	1216	/* Received in-sequence data, adjust ooseq data if:
andrewbonney	0:ec559500a63f	1217	- FIN has been received or
andrewbonney	0:ec559500a63f	1218	- inseq overlaps with ooseq */
andrewbonney	0:ec559500a63f	1219	if (pcb->ooseq != NULL) {
andrewbonney	0:ec559500a63f	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
andrewbonney	0:ec559500a63f	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
andrewbonney	0:ec559500a63f	1223	/* Received in-order FIN means anything that was received
andrewbonney	0:ec559500a63f	1224	* out of order must now have been received in-order, so
andrewbonney	0:ec559500a63f	1225	* bin the ooseq queue */
andrewbonney	0:ec559500a63f	1226	while (pcb->ooseq != NULL) {
andrewbonney	0:ec559500a63f	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
andrewbonney	0:ec559500a63f	1228	pcb->ooseq = pcb->ooseq->next;
andrewbonney	0:ec559500a63f	1229	tcp_seg_free(old_ooseq);
andrewbonney	0:ec559500a63f	1230	}
andrewbonney	0:ec559500a63f	1231	}
andrewbonney	0:ec559500a63f	1232	else {
andrewbonney	0:ec559500a63f	1233	next = pcb->ooseq;
andrewbonney	0:ec559500a63f	1234	/* Remove all segments on ooseq that are covered by inseg already.
andrewbonney	0:ec559500a63f	1235	* FIN is copied from ooseq to inseg if present. */
andrewbonney	0:ec559500a63f	1236	while (next &&
andrewbonney	0:ec559500a63f	1237	TCP_SEQ_GEQ(seqno + tcplen,
andrewbonney	0:ec559500a63f	1238	next->tcphdr->seqno + next->len)) {
andrewbonney	0:ec559500a63f	1239	/* inseg cannot have FIN here (already processed above) */
andrewbonney	0:ec559500a63f	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
andrewbonney	0:ec559500a63f	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
andrewbonney	0:ec559500a63f	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
andrewbonney	0:ec559500a63f	1243	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:ec559500a63f	1244	}
andrewbonney	0:ec559500a63f	1245	prev = next;
andrewbonney	0:ec559500a63f	1246	next = next->next;
andrewbonney	0:ec559500a63f	1247	tcp_seg_free(prev);
andrewbonney	0:ec559500a63f	1248	}
andrewbonney	0:ec559500a63f	1249	/* Now trim right side of inseg if it overlaps with the first
andrewbonney	0:ec559500a63f	1250	* segment on ooseq */
andrewbonney	0:ec559500a63f	1251	if (next &&
andrewbonney	0:ec559500a63f	1252	TCP_SEQ_GT(seqno + tcplen,
andrewbonney	0:ec559500a63f	1253	next->tcphdr->seqno)) {
andrewbonney	0:ec559500a63f	1254	/* inseg cannot have FIN here (already processed above) */
andrewbonney	0:ec559500a63f	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
andrewbonney	0:ec559500a63f	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
andrewbonney	0:ec559500a63f	1257	inseg.len -= 1;
andrewbonney	0:ec559500a63f	1258	}
andrewbonney	0:ec559500a63f	1259	pbuf_realloc(inseg.p, inseg.len);
andrewbonney	0:ec559500a63f	1260	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:ec559500a63f	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
andrewbonney	0:ec559500a63f	1262	(seqno + tcplen) == next->tcphdr->seqno);
andrewbonney	0:ec559500a63f	1263	}
andrewbonney	0:ec559500a63f	1264	pcb->ooseq = next;
andrewbonney	0:ec559500a63f	1265	}
andrewbonney	0:ec559500a63f	1266	}
andrewbonney	0:ec559500a63f	1267	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:ec559500a63f	1268
andrewbonney	0:ec559500a63f	1269	pcb->rcv_nxt = seqno + tcplen;
andrewbonney	0:ec559500a63f	1270
andrewbonney	0:ec559500a63f	1271	/* Update the receiver's (our) window. */
andrewbonney	0:ec559500a63f	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
andrewbonney	0:ec559500a63f	1273	pcb->rcv_wnd -= tcplen;
andrewbonney	0:ec559500a63f	1274
andrewbonney	0:ec559500a63f	1275	tcp_update_rcv_ann_wnd(pcb);
andrewbonney	0:ec559500a63f	1276
andrewbonney	0:ec559500a63f	1277	/* If there is data in the segment, we make preparations to
andrewbonney	0:ec559500a63f	1278	pass this up to the application. The ->recv_data variable
andrewbonney	0:ec559500a63f	1279	is used for holding the pbuf that goes to the
andrewbonney	0:ec559500a63f	1280	application. The code for reassembling out-of-sequence data
andrewbonney	0:ec559500a63f	1281	chains its data on this pbuf as well.
andrewbonney	0:ec559500a63f	1282
andrewbonney	0:ec559500a63f	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
andrewbonney	0:ec559500a63f	1284	be used to indicate to the application that the remote side has
andrewbonney	0:ec559500a63f	1285	closed its end of the connection. */
andrewbonney	0:ec559500a63f	1286	if (inseg.p->tot_len > 0) {
andrewbonney	0:ec559500a63f	1287	recv_data = inseg.p;
andrewbonney	0:ec559500a63f	1288	/* Since this pbuf now is the responsibility of the
andrewbonney	0:ec559500a63f	1289	application, we delete our reference to it so that we won't
andrewbonney	0:ec559500a63f	1290	(mistakingly) deallocate it. */
andrewbonney	0:ec559500a63f	1291	inseg.p = NULL;
andrewbonney	0:ec559500a63f	1292	}
andrewbonney	0:ec559500a63f	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
andrewbonney	0:ec559500a63f	1295	recv_flags \|= TF_GOT_FIN;
andrewbonney	0:ec559500a63f	1296	}
andrewbonney	0:ec559500a63f	1297
andrewbonney	0:ec559500a63f	1298	#if TCP_QUEUE_OOSEQ
andrewbonney	0:ec559500a63f	1299	/* We now check if we have segments on the ->ooseq queue that
andrewbonney	0:ec559500a63f	1300	are now in sequence. */
andrewbonney	0:ec559500a63f	1301	while (pcb->ooseq != NULL &&
andrewbonney	0:ec559500a63f	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
andrewbonney	0:ec559500a63f	1303
andrewbonney	0:ec559500a63f	1304	cseg = pcb->ooseq;
andrewbonney	0:ec559500a63f	1305	seqno = pcb->ooseq->tcphdr->seqno;
andrewbonney	0:ec559500a63f	1306
andrewbonney	0:ec559500a63f	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
andrewbonney	0:ec559500a63f	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
andrewbonney	0:ec559500a63f	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
andrewbonney	0:ec559500a63f	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
andrewbonney	0:ec559500a63f	1311
andrewbonney	0:ec559500a63f	1312	tcp_update_rcv_ann_wnd(pcb);
andrewbonney	0:ec559500a63f	1313
andrewbonney	0:ec559500a63f	1314	if (cseg->p->tot_len > 0) {
andrewbonney	0:ec559500a63f	1315	/* Chain this pbuf onto the pbuf that we will pass to
andrewbonney	0:ec559500a63f	1316	the application. */
andrewbonney	0:ec559500a63f	1317	if (recv_data) {
andrewbonney	0:ec559500a63f	1318	pbuf_cat(recv_data, cseg->p);
andrewbonney	0:ec559500a63f	1319	} else {
andrewbonney	0:ec559500a63f	1320	recv_data = cseg->p;
andrewbonney	0:ec559500a63f	1321	}
andrewbonney	0:ec559500a63f	1322	cseg->p = NULL;
andrewbonney	0:ec559500a63f	1323	}
andrewbonney	0:ec559500a63f	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
andrewbonney	0:ec559500a63f	1326	recv_flags \|= TF_GOT_FIN;
andrewbonney	0:ec559500a63f	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
andrewbonney	0:ec559500a63f	1328	pcb->state = CLOSE_WAIT;
andrewbonney	0:ec559500a63f	1329	}
andrewbonney	0:ec559500a63f	1330	}
andrewbonney	0:ec559500a63f	1331
andrewbonney	0:ec559500a63f	1332	pcb->ooseq = cseg->next;
andrewbonney	0:ec559500a63f	1333	tcp_seg_free(cseg);
andrewbonney	0:ec559500a63f	1334	}
andrewbonney	0:ec559500a63f	1335	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:ec559500a63f	1336
andrewbonney	0:ec559500a63f	1337
andrewbonney	0:ec559500a63f	1338	/* Acknowledge the segment(s). */
andrewbonney	0:ec559500a63f	1339	tcp_ack(pcb);
andrewbonney	0:ec559500a63f	1340
andrewbonney	0:ec559500a63f	1341	} else {
andrewbonney	0:ec559500a63f	1342	/* We get here if the incoming segment is out-of-sequence. */
andrewbonney	0:ec559500a63f	1343	tcp_send_empty_ack(pcb);
andrewbonney	0:ec559500a63f	1344	#if TCP_QUEUE_OOSEQ
andrewbonney	0:ec559500a63f	1345	/* We queue the segment on the ->ooseq queue. */
andrewbonney	0:ec559500a63f	1346	if (pcb->ooseq == NULL) {
andrewbonney	0:ec559500a63f	1347	pcb->ooseq = tcp_seg_copy(&inseg);
andrewbonney	0:ec559500a63f	1348	} else {
andrewbonney	0:ec559500a63f	1349	/* If the queue is not empty, we walk through the queue and
andrewbonney	0:ec559500a63f	1350	try to find a place where the sequence number of the
andrewbonney	0:ec559500a63f	1351	incoming segment is between the sequence numbers of the
andrewbonney	0:ec559500a63f	1352	previous and the next segment on the ->ooseq queue. That is
andrewbonney	0:ec559500a63f	1353	the place where we put the incoming segment. If needed, we
andrewbonney	0:ec559500a63f	1354	trim the second edges of the previous and the incoming
andrewbonney	0:ec559500a63f	1355	segment so that it will fit into the sequence.
andrewbonney	0:ec559500a63f	1356
andrewbonney	0:ec559500a63f	1357	If the incoming segment has the same sequence number as a
andrewbonney	0:ec559500a63f	1358	segment on the ->ooseq queue, we discard the segment that
andrewbonney	0:ec559500a63f	1359	contains less data. */
andrewbonney	0:ec559500a63f	1360
andrewbonney	0:ec559500a63f	1361	prev = NULL;
andrewbonney	0:ec559500a63f	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
andrewbonney	0:ec559500a63f	1363	if (seqno == next->tcphdr->seqno) {
andrewbonney	0:ec559500a63f	1364	/* The sequence number of the incoming segment is the
andrewbonney	0:ec559500a63f	1365	same as the sequence number of the segment on
andrewbonney	0:ec559500a63f	1366	->ooseq. We check the lengths to see which one to
andrewbonney	0:ec559500a63f	1367	discard. */
andrewbonney	0:ec559500a63f	1368	if (inseg.len > next->len) {
andrewbonney	0:ec559500a63f	1369	/* The incoming segment is larger than the old
andrewbonney	0:ec559500a63f	1370	segment. We replace some segments with the new
andrewbonney	0:ec559500a63f	1371	one. */
andrewbonney	0:ec559500a63f	1372	cseg = tcp_seg_copy(&inseg);
andrewbonney	0:ec559500a63f	1373	if (cseg != NULL) {
andrewbonney	0:ec559500a63f	1374	if (prev != NULL) {
andrewbonney	0:ec559500a63f	1375	prev->next = cseg;
andrewbonney	0:ec559500a63f	1376	} else {
andrewbonney	0:ec559500a63f	1377	pcb->ooseq = cseg;
andrewbonney	0:ec559500a63f	1378	}
andrewbonney	0:ec559500a63f	1379	tcp_oos_insert_segment(cseg, next);
andrewbonney	0:ec559500a63f	1380	}
andrewbonney	0:ec559500a63f	1381	break;
andrewbonney	0:ec559500a63f	1382	} else {
andrewbonney	0:ec559500a63f	1383	/* Either the lenghts are the same or the incoming
andrewbonney	0:ec559500a63f	1384	segment was smaller than the old one; in either
andrewbonney	0:ec559500a63f	1385	case, we ditch the incoming segment. */
andrewbonney	0:ec559500a63f	1386	break;
andrewbonney	0:ec559500a63f	1387	}
andrewbonney	0:ec559500a63f	1388	} else {
andrewbonney	0:ec559500a63f	1389	if (prev == NULL) {
andrewbonney	0:ec559500a63f	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
andrewbonney	0:ec559500a63f	1391	/* The sequence number of the incoming segment is lower
andrewbonney	0:ec559500a63f	1392	than the sequence number of the first segment on the
andrewbonney	0:ec559500a63f	1393	queue. We put the incoming segment first on the
andrewbonney	0:ec559500a63f	1394	queue. */
andrewbonney	0:ec559500a63f	1395	cseg = tcp_seg_copy(&inseg);
andrewbonney	0:ec559500a63f	1396	if (cseg != NULL) {
andrewbonney	0:ec559500a63f	1397	pcb->ooseq = cseg;
andrewbonney	0:ec559500a63f	1398	tcp_oos_insert_segment(cseg, next);
andrewbonney	0:ec559500a63f	1399	}
andrewbonney	0:ec559500a63f	1400	break;
andrewbonney	0:ec559500a63f	1401	}
andrewbonney	0:ec559500a63f	1402	} else {
andrewbonney	0:ec559500a63f	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
andrewbonney	0:ec559500a63f	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
andrewbonney	0:ec559500a63f	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
andrewbonney	0:ec559500a63f	1406	/* The sequence number of the incoming segment is in
andrewbonney	0:ec559500a63f	1407	between the sequence numbers of the previous and
andrewbonney	0:ec559500a63f	1408	the next segment on ->ooseq. We trim trim the previous
andrewbonney	0:ec559500a63f	1409	segment, delete next segments that included in received segment
andrewbonney	0:ec559500a63f	1410	and trim received, if needed. */
andrewbonney	0:ec559500a63f	1411	cseg = tcp_seg_copy(&inseg);
andrewbonney	0:ec559500a63f	1412	if (cseg != NULL) {
andrewbonney	0:ec559500a63f	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
andrewbonney	0:ec559500a63f	1414	/* We need to trim the prev segment. */
andrewbonney	0:ec559500a63f	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
andrewbonney	0:ec559500a63f	1416	pbuf_realloc(prev->p, prev->len);
andrewbonney	0:ec559500a63f	1417	}
andrewbonney	0:ec559500a63f	1418	prev->next = cseg;
andrewbonney	0:ec559500a63f	1419	tcp_oos_insert_segment(cseg, next);
andrewbonney	0:ec559500a63f	1420	}
andrewbonney	0:ec559500a63f	1421	break;
andrewbonney	0:ec559500a63f	1422	}
andrewbonney	0:ec559500a63f	1423	}
andrewbonney	0:ec559500a63f	1424	/* If the "next" segment is the last segment on the
andrewbonney	0:ec559500a63f	1425	ooseq queue, we add the incoming segment to the end
andrewbonney	0:ec559500a63f	1426	of the list. */
andrewbonney	0:ec559500a63f	1427	if (next->next == NULL &&
andrewbonney	0:ec559500a63f	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
andrewbonney	0:ec559500a63f	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	1430	/* segment "next" already contains all data */
andrewbonney	0:ec559500a63f	1431	break;
andrewbonney	0:ec559500a63f	1432	}
andrewbonney	0:ec559500a63f	1433	next->next = tcp_seg_copy(&inseg);
andrewbonney	0:ec559500a63f	1434	if (next->next != NULL) {
andrewbonney	0:ec559500a63f	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
andrewbonney	0:ec559500a63f	1436	/* We need to trim the last segment. */
andrewbonney	0:ec559500a63f	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
andrewbonney	0:ec559500a63f	1438	pbuf_realloc(next->p, next->len);
andrewbonney	0:ec559500a63f	1439	}
andrewbonney	0:ec559500a63f	1440	/* check if the remote side overruns our receive window */
andrewbonney	0:ec559500a63f	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
andrewbonney	0:ec559500a63f	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
andrewbonney	0:ec559500a63f	1443	("tcp_receive: other end overran receive window"
andrewbonney	0:ec559500a63f	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
andrewbonney	0:ec559500a63f	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:ec559500a63f	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
andrewbonney	0:ec559500a63f	1447	/* Must remove the FIN from the header as we're trimming
andrewbonney	0:ec559500a63f	1448	* that byte of sequence-space from the packet */
andrewbonney	0:ec559500a63f	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
andrewbonney	0:ec559500a63f	1450	}
andrewbonney	0:ec559500a63f	1451	/* Adjust length of segment to fit in the window. */
andrewbonney	0:ec559500a63f	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
andrewbonney	0:ec559500a63f	1453	pbuf_realloc(next->next->p, next->next->len);
andrewbonney	0:ec559500a63f	1454	tcplen = TCP_TCPLEN(next->next);
andrewbonney	0:ec559500a63f	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
andrewbonney	0:ec559500a63f	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:ec559500a63f	1457	}
andrewbonney	0:ec559500a63f	1458	}
andrewbonney	0:ec559500a63f	1459	break;
andrewbonney	0:ec559500a63f	1460	}
andrewbonney	0:ec559500a63f	1461	}
andrewbonney	0:ec559500a63f	1462	prev = next;
andrewbonney	0:ec559500a63f	1463	}
andrewbonney	0:ec559500a63f	1464	}
andrewbonney	0:ec559500a63f	1465	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:ec559500a63f	1466
andrewbonney	0:ec559500a63f	1467	}
andrewbonney	0:ec559500a63f	1468	} else {
andrewbonney	0:ec559500a63f	1469	/* The incoming segment is not withing the window. */
andrewbonney	0:ec559500a63f	1470	tcp_send_empty_ack(pcb);
andrewbonney	0:ec559500a63f	1471	}
andrewbonney	0:ec559500a63f	1472	} else {
andrewbonney	0:ec559500a63f	1473	/* Segments with length 0 is taken care of here. Segments that
andrewbonney	0:ec559500a63f	1474	fall out of the window are ACKed. */
andrewbonney	0:ec559500a63f	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
andrewbonney	0:ec559500a63f	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
andrewbonney	0:ec559500a63f	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
andrewbonney	0:ec559500a63f	1478	tcp_ack_now(pcb);
andrewbonney	0:ec559500a63f	1479	}
andrewbonney	0:ec559500a63f	1480	}
andrewbonney	0:ec559500a63f	1481	}
andrewbonney	0:ec559500a63f	1482
andrewbonney	0:ec559500a63f	1483	/**
andrewbonney	0:ec559500a63f	1484	* Parses the options contained in the incoming segment.
andrewbonney	0:ec559500a63f	1485	*
andrewbonney	0:ec559500a63f	1486	* Called from tcp_listen_input() and tcp_process().
andrewbonney	0:ec559500a63f	1487	* Currently, only the MSS option is supported!
andrewbonney	0:ec559500a63f	1488	*
andrewbonney	0:ec559500a63f	1489	* @param pcb the tcp_pcb for which a segment arrived
andrewbonney	0:ec559500a63f	1490	*/
andrewbonney	0:ec559500a63f	1491	static void
andrewbonney	0:ec559500a63f	1492	tcp_parseopt(struct tcp_pcb *pcb)
andrewbonney	0:ec559500a63f	1493	{
andrewbonney	0:ec559500a63f	1494	u16_t c, max_c;
andrewbonney	0:ec559500a63f	1495	u16_t mss;
andrewbonney	0:ec559500a63f	1496	u8_t *opts, opt;
andrewbonney	0:ec559500a63f	1497	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	1498	u32_t tsval;
andrewbonney	0:ec559500a63f	1499	#endif
andrewbonney	0:ec559500a63f	1500
andrewbonney	0:ec559500a63f	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
andrewbonney	0:ec559500a63f	1502
andrewbonney	0:ec559500a63f	1503	/* Parse the TCP MSS option, if present. */
andrewbonney	0:ec559500a63f	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
andrewbonney	0:ec559500a63f	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
andrewbonney	0:ec559500a63f	1506	for (c = 0; c < max_c; ) {
andrewbonney	0:ec559500a63f	1507	opt = opts[c];
andrewbonney	0:ec559500a63f	1508	switch (opt) {
andrewbonney	0:ec559500a63f	1509	case 0x00:
andrewbonney	0:ec559500a63f	1510	/* End of options. */
andrewbonney	0:ec559500a63f	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
andrewbonney	0:ec559500a63f	1512	return;
andrewbonney	0:ec559500a63f	1513	case 0x01:
andrewbonney	0:ec559500a63f	1514	/* NOP option. */
andrewbonney	0:ec559500a63f	1515	++c;
andrewbonney	0:ec559500a63f	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
andrewbonney	0:ec559500a63f	1517	break;
andrewbonney	0:ec559500a63f	1518	case 0x02:
andrewbonney	0:ec559500a63f	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
andrewbonney	0:ec559500a63f	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
andrewbonney	0:ec559500a63f	1521	/* Bad length */
andrewbonney	0:ec559500a63f	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
andrewbonney	0:ec559500a63f	1523	return;
andrewbonney	0:ec559500a63f	1524	}
andrewbonney	0:ec559500a63f	1525	/* An MSS option with the right option length. */
andrewbonney	0:ec559500a63f	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
andrewbonney	0:ec559500a63f	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
andrewbonney	0:ec559500a63f	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
andrewbonney	0:ec559500a63f	1529	/* Advance to next option */
andrewbonney	0:ec559500a63f	1530	c += 0x04;
andrewbonney	0:ec559500a63f	1531	break;
andrewbonney	0:ec559500a63f	1532	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:ec559500a63f	1533	case 0x08:
andrewbonney	0:ec559500a63f	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
andrewbonney	0:ec559500a63f	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
andrewbonney	0:ec559500a63f	1536	/* Bad length */
andrewbonney	0:ec559500a63f	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
andrewbonney	0:ec559500a63f	1538	return;
andrewbonney	0:ec559500a63f	1539	}
andrewbonney	0:ec559500a63f	1540	/* TCP timestamp option with valid length */
andrewbonney	0:ec559500a63f	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
andrewbonney	0:ec559500a63f	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
andrewbonney	0:ec559500a63f	1543	if (flags & TCP_SYN) {
andrewbonney	0:ec559500a63f	1544	pcb->ts_recent = ntohl(tsval);
andrewbonney	0:ec559500a63f	1545	pcb->flags \|= TF_TIMESTAMP;
andrewbonney	0:ec559500a63f	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
andrewbonney	0:ec559500a63f	1547	pcb->ts_recent = ntohl(tsval);
andrewbonney	0:ec559500a63f	1548	}
andrewbonney	0:ec559500a63f	1549	/* Advance to next option */
andrewbonney	0:ec559500a63f	1550	c += 0x0A;
andrewbonney	0:ec559500a63f	1551	break;
andrewbonney	0:ec559500a63f	1552	#endif
andrewbonney	0:ec559500a63f	1553	default:
andrewbonney	0:ec559500a63f	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
andrewbonney	0:ec559500a63f	1555	if (opts[c + 1] == 0) {
andrewbonney	0:ec559500a63f	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
andrewbonney	0:ec559500a63f	1557	/* If the length field is zero, the options are malformed
andrewbonney	0:ec559500a63f	1558	and we don't process them further. */
andrewbonney	0:ec559500a63f	1559	return;
andrewbonney	0:ec559500a63f	1560	}
andrewbonney	0:ec559500a63f	1561	/* All other options have a length field, so that we easily
andrewbonney	0:ec559500a63f	1562	can skip past them. */
andrewbonney	0:ec559500a63f	1563	c += opts[c + 1];
andrewbonney	0:ec559500a63f	1564	}
andrewbonney	0:ec559500a63f	1565	}
andrewbonney	0:ec559500a63f	1566	}
andrewbonney	0:ec559500a63f	1567	}
andrewbonney	0:ec559500a63f	1568
andrewbonney	0:ec559500a63f	1569	#endif /* LWIP_TCP */

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Type:	Library
Created:	08 Apr 2011
Imports:	86
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	3

lwip/core/tcp_in.c@0:ec559500a63f, 2011-04-08 (annotated)

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