NetServicesMin - Stripped down version of Segundos NetService libr…

Users » hlipka » Code » NetServicesMin

Stripped down version of Segundos NetService library (http://mbed.org/users/segundo/libraries/NetServices ). I have removed all NetServices, and all functions which had been disabled. Use this version when you need only pure TCP or UDP functions - this library compiles faster.

Dependencies: lwip lwip-sys

Dependents: christmasLights device_server pop3demo device_server_udp ... more

lwip/core/tcp_in.c@0:8b387bed54c2, 2011-01-10 (annotated)

Committer:: hlipka
Date:: Mon Jan 10 21:03:11 2011 +0000
Revision:: 0:8b387bed54c2

initial version

Who changed what in which revision?

User	Revision	Line number	New contents of line
hlipka	0:8b387bed54c2	1	/**
hlipka	0:8b387bed54c2	2	* @file
hlipka	0:8b387bed54c2	3	* Transmission Control Protocol, incoming traffic
hlipka	0:8b387bed54c2	4	*
hlipka	0:8b387bed54c2	5	* The input processing functions of the TCP layer.
hlipka	0:8b387bed54c2	6	*
hlipka	0:8b387bed54c2	7	* These functions are generally called in the order (ip_input() ->)
hlipka	0:8b387bed54c2	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
hlipka	0:8b387bed54c2	9	*
hlipka	0:8b387bed54c2	10	*/
hlipka	0:8b387bed54c2	11
hlipka	0:8b387bed54c2	12	/*
hlipka	0:8b387bed54c2	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
hlipka	0:8b387bed54c2	14	* All rights reserved.
hlipka	0:8b387bed54c2	15	*
hlipka	0:8b387bed54c2	16	* Redistribution and use in source and binary forms, with or without modification,
hlipka	0:8b387bed54c2	17	* are permitted provided that the following conditions are met:
hlipka	0:8b387bed54c2	18	*
hlipka	0:8b387bed54c2	19	* 1. Redistributions of source code must retain the above copyright notice,
hlipka	0:8b387bed54c2	20	* this list of conditions and the following disclaimer.
hlipka	0:8b387bed54c2	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
hlipka	0:8b387bed54c2	22	* this list of conditions and the following disclaimer in the documentation
hlipka	0:8b387bed54c2	23	* and/or other materials provided with the distribution.
hlipka	0:8b387bed54c2	24	* 3. The name of the author may not be used to endorse or promote products
hlipka	0:8b387bed54c2	25	* derived from this software without specific prior written permission.
hlipka	0:8b387bed54c2	26	*
hlipka	0:8b387bed54c2	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
hlipka	0:8b387bed54c2	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
hlipka	0:8b387bed54c2	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
hlipka	0:8b387bed54c2	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
hlipka	0:8b387bed54c2	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
hlipka	0:8b387bed54c2	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
hlipka	0:8b387bed54c2	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
hlipka	0:8b387bed54c2	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
hlipka	0:8b387bed54c2	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
hlipka	0:8b387bed54c2	36	* OF SUCH DAMAGE.
hlipka	0:8b387bed54c2	37	*
hlipka	0:8b387bed54c2	38	* This file is part of the lwIP TCP/IP stack.
hlipka	0:8b387bed54c2	39	*
hlipka	0:8b387bed54c2	40	* Author: Adam Dunkels <adam@sics.se>
hlipka	0:8b387bed54c2	41	*
hlipka	0:8b387bed54c2	42	*/
hlipka	0:8b387bed54c2	43
hlipka	0:8b387bed54c2	44	#include "lwip/opt.h"
hlipka	0:8b387bed54c2	45
hlipka	0:8b387bed54c2	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
hlipka	0:8b387bed54c2	47
hlipka	0:8b387bed54c2	48	#include "lwip/tcp_impl.h"
hlipka	0:8b387bed54c2	49	#include "lwip/def.h"
hlipka	0:8b387bed54c2	50	#include "lwip/ip_addr.h"
hlipka	0:8b387bed54c2	51	#include "lwip/netif.h"
hlipka	0:8b387bed54c2	52	#include "lwip/mem.h"
hlipka	0:8b387bed54c2	53	#include "lwip/memp.h"
hlipka	0:8b387bed54c2	54	#include "lwip/inet_chksum.h"
hlipka	0:8b387bed54c2	55	#include "lwip/stats.h"
hlipka	0:8b387bed54c2	56	#include "lwip/snmp.h"
hlipka	0:8b387bed54c2	57	#include "arch/perf.h"
hlipka	0:8b387bed54c2	58
hlipka	0:8b387bed54c2	59	/* These variables are global to all functions involved in the input
hlipka	0:8b387bed54c2	60	processing of TCP segments. They are set by the tcp_input()
hlipka	0:8b387bed54c2	61	function. */
hlipka	0:8b387bed54c2	62	static struct tcp_seg inseg;
hlipka	0:8b387bed54c2	63	static struct tcp_hdr *tcphdr;
hlipka	0:8b387bed54c2	64	static struct ip_hdr *iphdr;
hlipka	0:8b387bed54c2	65	static u32_t seqno, ackno;
hlipka	0:8b387bed54c2	66	static u8_t flags;
hlipka	0:8b387bed54c2	67	static u16_t tcplen;
hlipka	0:8b387bed54c2	68
hlipka	0:8b387bed54c2	69	static u8_t recv_flags;
hlipka	0:8b387bed54c2	70	static struct pbuf *recv_data;
hlipka	0:8b387bed54c2	71
hlipka	0:8b387bed54c2	72	struct tcp_pcb *tcp_input_pcb;
hlipka	0:8b387bed54c2	73
hlipka	0:8b387bed54c2	74	/* Forward declarations. */
hlipka	0:8b387bed54c2	75	static err_t tcp_process(struct tcp_pcb *pcb);
hlipka	0:8b387bed54c2	76	static void tcp_receive(struct tcp_pcb *pcb);
hlipka	0:8b387bed54c2	77	static void tcp_parseopt(struct tcp_pcb *pcb);
hlipka	0:8b387bed54c2	78
hlipka	0:8b387bed54c2	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
hlipka	0:8b387bed54c2	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
hlipka	0:8b387bed54c2	81
hlipka	0:8b387bed54c2	82	/**
hlipka	0:8b387bed54c2	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
hlipka	0:8b387bed54c2	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
hlipka	0:8b387bed54c2	85	* the TCP finite state machine. This function is called by the IP layer (in
hlipka	0:8b387bed54c2	86	* ip_input()).
hlipka	0:8b387bed54c2	87	*
hlipka	0:8b387bed54c2	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
hlipka	0:8b387bed54c2	89	* @param inp network interface on which this segment was received
hlipka	0:8b387bed54c2	90	*/
hlipka	0:8b387bed54c2	91	void
hlipka	0:8b387bed54c2	92	tcp_input(struct pbuf p, struct netif inp)
hlipka	0:8b387bed54c2	93	{
hlipka	0:8b387bed54c2	94	struct tcp_pcb pcb, prev;
hlipka	0:8b387bed54c2	95	struct tcp_pcb_listen *lpcb;
hlipka	0:8b387bed54c2	96	#if SO_REUSE
hlipka	0:8b387bed54c2	97	struct tcp_pcb *lpcb_prev = NULL;
hlipka	0:8b387bed54c2	98	struct tcp_pcb_listen *lpcb_any = NULL;
hlipka	0:8b387bed54c2	99	#endif /* SO_REUSE */
hlipka	0:8b387bed54c2	100	u8_t hdrlen;
hlipka	0:8b387bed54c2	101	err_t err;
hlipka	0:8b387bed54c2	102
hlipka	0:8b387bed54c2	103	PERF_START;
hlipka	0:8b387bed54c2	104
hlipka	0:8b387bed54c2	105	TCP_STATS_INC(tcp.recv);
hlipka	0:8b387bed54c2	106	snmp_inc_tcpinsegs();
hlipka	0:8b387bed54c2	107
hlipka	0:8b387bed54c2	108	iphdr = (struct ip_hdr *)p->payload;
hlipka	0:8b387bed54c2	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
hlipka	0:8b387bed54c2	110
hlipka	0:8b387bed54c2	111	#if TCP_INPUT_DEBUG
hlipka	0:8b387bed54c2	112	tcp_debug_print(tcphdr);
hlipka	0:8b387bed54c2	113	#endif
hlipka	0:8b387bed54c2	114
hlipka	0:8b387bed54c2	115	/* remove header from payload */
hlipka	0:8b387bed54c2	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
hlipka	0:8b387bed54c2	117	/* drop short packets */
hlipka	0:8b387bed54c2	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
hlipka	0:8b387bed54c2	119	TCP_STATS_INC(tcp.lenerr);
hlipka	0:8b387bed54c2	120	TCP_STATS_INC(tcp.drop);
hlipka	0:8b387bed54c2	121	snmp_inc_tcpinerrs();
hlipka	0:8b387bed54c2	122	pbuf_free(p);
hlipka	0:8b387bed54c2	123	return;
hlipka	0:8b387bed54c2	124	}
hlipka	0:8b387bed54c2	125
hlipka	0:8b387bed54c2	126	/* Don't even process incoming broadcasts/multicasts. */
hlipka	0:8b387bed54c2	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
hlipka	0:8b387bed54c2	128	ip_addr_ismulticast(&current_iphdr_dest)) {
hlipka	0:8b387bed54c2	129	TCP_STATS_INC(tcp.proterr);
hlipka	0:8b387bed54c2	130	TCP_STATS_INC(tcp.drop);
hlipka	0:8b387bed54c2	131	snmp_inc_tcpinerrs();
hlipka	0:8b387bed54c2	132	pbuf_free(p);
hlipka	0:8b387bed54c2	133	return;
hlipka	0:8b387bed54c2	134	}
hlipka	0:8b387bed54c2	135
hlipka	0:8b387bed54c2	136	#if CHECKSUM_CHECK_TCP
hlipka	0:8b387bed54c2	137	/* Verify TCP checksum. */
hlipka	0:8b387bed54c2	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
hlipka	0:8b387bed54c2	139	IP_PROTO_TCP, p->tot_len) != 0) {
hlipka	0:8b387bed54c2	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
hlipka	0:8b387bed54c2	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
hlipka	0:8b387bed54c2	142	IP_PROTO_TCP, p->tot_len)));
hlipka	0:8b387bed54c2	143	#if TCP_DEBUG
hlipka	0:8b387bed54c2	144	tcp_debug_print(tcphdr);
hlipka	0:8b387bed54c2	145	#endif /* TCP_DEBUG */
hlipka	0:8b387bed54c2	146	TCP_STATS_INC(tcp.chkerr);
hlipka	0:8b387bed54c2	147	TCP_STATS_INC(tcp.drop);
hlipka	0:8b387bed54c2	148	snmp_inc_tcpinerrs();
hlipka	0:8b387bed54c2	149	pbuf_free(p);
hlipka	0:8b387bed54c2	150	return;
hlipka	0:8b387bed54c2	151	}
hlipka	0:8b387bed54c2	152	#endif
hlipka	0:8b387bed54c2	153
hlipka	0:8b387bed54c2	154	/* Move the payload pointer in the pbuf so that it points to the
hlipka	0:8b387bed54c2	155	TCP data instead of the TCP header. */
hlipka	0:8b387bed54c2	156	hdrlen = TCPH_HDRLEN(tcphdr);
hlipka	0:8b387bed54c2	157	if(pbuf_header(p, -(hdrlen * 4))){
hlipka	0:8b387bed54c2	158	/* drop short packets */
hlipka	0:8b387bed54c2	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
hlipka	0:8b387bed54c2	160	TCP_STATS_INC(tcp.lenerr);
hlipka	0:8b387bed54c2	161	TCP_STATS_INC(tcp.drop);
hlipka	0:8b387bed54c2	162	snmp_inc_tcpinerrs();
hlipka	0:8b387bed54c2	163	pbuf_free(p);
hlipka	0:8b387bed54c2	164	return;
hlipka	0:8b387bed54c2	165	}
hlipka	0:8b387bed54c2	166
hlipka	0:8b387bed54c2	167	/* Convert fields in TCP header to host byte order. */
hlipka	0:8b387bed54c2	168	tcphdr->src = ntohs(tcphdr->src);
hlipka	0:8b387bed54c2	169	tcphdr->dest = ntohs(tcphdr->dest);
hlipka	0:8b387bed54c2	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
hlipka	0:8b387bed54c2	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
hlipka	0:8b387bed54c2	172	tcphdr->wnd = ntohs(tcphdr->wnd);
hlipka	0:8b387bed54c2	173
hlipka	0:8b387bed54c2	174	flags = TCPH_FLAGS(tcphdr);
hlipka	0:8b387bed54c2	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
hlipka	0:8b387bed54c2	176
hlipka	0:8b387bed54c2	177	/* Demultiplex an incoming segment. First, we check if it is destined
hlipka	0:8b387bed54c2	178	for an active connection. */
hlipka	0:8b387bed54c2	179	prev = NULL;
hlipka	0:8b387bed54c2	180
hlipka	0:8b387bed54c2	181
hlipka	0:8b387bed54c2	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
hlipka	0:8b387bed54c2	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
hlipka	0:8b387bed54c2	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
hlipka	0:8b387bed54c2	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
hlipka	0:8b387bed54c2	186	if (pcb->remote_port == tcphdr->src &&
hlipka	0:8b387bed54c2	187	pcb->local_port == tcphdr->dest &&
hlipka	0:8b387bed54c2	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
hlipka	0:8b387bed54c2	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
hlipka	0:8b387bed54c2	190
hlipka	0:8b387bed54c2	191	/* Move this PCB to the front of the list so that subsequent
hlipka	0:8b387bed54c2	192	lookups will be faster (we exploit locality in TCP segment
hlipka	0:8b387bed54c2	193	arrivals). */
hlipka	0:8b387bed54c2	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
hlipka	0:8b387bed54c2	195	if (prev != NULL) {
hlipka	0:8b387bed54c2	196	prev->next = pcb->next;
hlipka	0:8b387bed54c2	197	pcb->next = tcp_active_pcbs;
hlipka	0:8b387bed54c2	198	tcp_active_pcbs = pcb;
hlipka	0:8b387bed54c2	199	}
hlipka	0:8b387bed54c2	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
hlipka	0:8b387bed54c2	201	break;
hlipka	0:8b387bed54c2	202	}
hlipka	0:8b387bed54c2	203	prev = pcb;
hlipka	0:8b387bed54c2	204	}
hlipka	0:8b387bed54c2	205
hlipka	0:8b387bed54c2	206	if (pcb == NULL) {
hlipka	0:8b387bed54c2	207	/* If it did not go to an active connection, we check the connections
hlipka	0:8b387bed54c2	208	in the TIME-WAIT state. */
hlipka	0:8b387bed54c2	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
hlipka	0:8b387bed54c2	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
hlipka	0:8b387bed54c2	211	if (pcb->remote_port == tcphdr->src &&
hlipka	0:8b387bed54c2	212	pcb->local_port == tcphdr->dest &&
hlipka	0:8b387bed54c2	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
hlipka	0:8b387bed54c2	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
hlipka	0:8b387bed54c2	215	/* We don't really care enough to move this PCB to the front
hlipka	0:8b387bed54c2	216	of the list since we are not very likely to receive that
hlipka	0:8b387bed54c2	217	many segments for connections in TIME-WAIT. */
hlipka	0:8b387bed54c2	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
hlipka	0:8b387bed54c2	219	tcp_timewait_input(pcb);
hlipka	0:8b387bed54c2	220	pbuf_free(p);
hlipka	0:8b387bed54c2	221	return;
hlipka	0:8b387bed54c2	222	}
hlipka	0:8b387bed54c2	223	}
hlipka	0:8b387bed54c2	224
hlipka	0:8b387bed54c2	225	/* Finally, if we still did not get a match, we check all PCBs that
hlipka	0:8b387bed54c2	226	are LISTENing for incoming connections. */
hlipka	0:8b387bed54c2	227	prev = NULL;
hlipka	0:8b387bed54c2	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
hlipka	0:8b387bed54c2	229	if (lpcb->local_port == tcphdr->dest) {
hlipka	0:8b387bed54c2	230	#if SO_REUSE
hlipka	0:8b387bed54c2	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
hlipka	0:8b387bed54c2	232	/* found an exact match */
hlipka	0:8b387bed54c2	233	break;
hlipka	0:8b387bed54c2	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
hlipka	0:8b387bed54c2	235	/* found an ANY-match */
hlipka	0:8b387bed54c2	236	lpcb_any = lpcb;
hlipka	0:8b387bed54c2	237	lpcb_prev = prev;
hlipka	0:8b387bed54c2	238	}
hlipka	0:8b387bed54c2	239	#else /* SO_REUSE */
hlipka	0:8b387bed54c2	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
hlipka	0:8b387bed54c2	241	ip_addr_isany(&(lpcb->local_ip))) {
hlipka	0:8b387bed54c2	242	/* found a match */
hlipka	0:8b387bed54c2	243	break;
hlipka	0:8b387bed54c2	244	}
hlipka	0:8b387bed54c2	245	#endif /* SO_REUSE */
hlipka	0:8b387bed54c2	246	}
hlipka	0:8b387bed54c2	247	prev = (struct tcp_pcb *)lpcb;
hlipka	0:8b387bed54c2	248	}
hlipka	0:8b387bed54c2	249	#if SO_REUSE
hlipka	0:8b387bed54c2	250	/* first try specific local IP */
hlipka	0:8b387bed54c2	251	if (lpcb == NULL) {
hlipka	0:8b387bed54c2	252	/* only pass to ANY if no specific local IP has been found */
hlipka	0:8b387bed54c2	253	lpcb = lpcb_any;
hlipka	0:8b387bed54c2	254	prev = lpcb_prev;
hlipka	0:8b387bed54c2	255	}
hlipka	0:8b387bed54c2	256	#endif /* SO_REUSE */
hlipka	0:8b387bed54c2	257	if (lpcb != NULL) {
hlipka	0:8b387bed54c2	258	/* Move this PCB to the front of the list so that subsequent
hlipka	0:8b387bed54c2	259	lookups will be faster (we exploit locality in TCP segment
hlipka	0:8b387bed54c2	260	arrivals). */
hlipka	0:8b387bed54c2	261	if (prev != NULL) {
hlipka	0:8b387bed54c2	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
hlipka	0:8b387bed54c2	263	/* our successor is the remainder of the listening list */
hlipka	0:8b387bed54c2	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
hlipka	0:8b387bed54c2	265	/* put this listening pcb at the head of the listening list */
hlipka	0:8b387bed54c2	266	tcp_listen_pcbs.listen_pcbs = lpcb;
hlipka	0:8b387bed54c2	267	}
hlipka	0:8b387bed54c2	268
hlipka	0:8b387bed54c2	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
hlipka	0:8b387bed54c2	270	tcp_listen_input(lpcb);
hlipka	0:8b387bed54c2	271	pbuf_free(p);
hlipka	0:8b387bed54c2	272	return;
hlipka	0:8b387bed54c2	273	}
hlipka	0:8b387bed54c2	274	}
hlipka	0:8b387bed54c2	275
hlipka	0:8b387bed54c2	276	#if TCP_INPUT_DEBUG
hlipka	0:8b387bed54c2	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
hlipka	0:8b387bed54c2	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
hlipka	0:8b387bed54c2	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
hlipka	0:8b387bed54c2	280	#endif /* TCP_INPUT_DEBUG */
hlipka	0:8b387bed54c2	281
hlipka	0:8b387bed54c2	282
hlipka	0:8b387bed54c2	283	if (pcb != NULL) {
hlipka	0:8b387bed54c2	284	/* The incoming segment belongs to a connection. */
hlipka	0:8b387bed54c2	285	#if TCP_INPUT_DEBUG
hlipka	0:8b387bed54c2	286	#if TCP_DEBUG
hlipka	0:8b387bed54c2	287	tcp_debug_print_state(pcb->state);
hlipka	0:8b387bed54c2	288	#endif /* TCP_DEBUG */
hlipka	0:8b387bed54c2	289	#endif /* TCP_INPUT_DEBUG */
hlipka	0:8b387bed54c2	290
hlipka	0:8b387bed54c2	291	/* Set up a tcp_seg structure. */
hlipka	0:8b387bed54c2	292	inseg.next = NULL;
hlipka	0:8b387bed54c2	293	inseg.len = p->tot_len;
hlipka	0:8b387bed54c2	294	inseg.dataptr = p->payload;
hlipka	0:8b387bed54c2	295	inseg.p = p;
hlipka	0:8b387bed54c2	296	inseg.tcphdr = tcphdr;
hlipka	0:8b387bed54c2	297
hlipka	0:8b387bed54c2	298	recv_data = NULL;
hlipka	0:8b387bed54c2	299	recv_flags = 0;
hlipka	0:8b387bed54c2	300
hlipka	0:8b387bed54c2	301	/* If there is data which was previously "refused" by upper layer */
hlipka	0:8b387bed54c2	302	if (pcb->refused_data != NULL) {
hlipka	0:8b387bed54c2	303	/* Notify again application with data previously received. */
hlipka	0:8b387bed54c2	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
hlipka	0:8b387bed54c2	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
hlipka	0:8b387bed54c2	306	if (err == ERR_OK) {
hlipka	0:8b387bed54c2	307	pcb->refused_data = NULL;
hlipka	0:8b387bed54c2	308	} else {
hlipka	0:8b387bed54c2	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
hlipka	0:8b387bed54c2	310	/* drop incoming packets, because pcb is "full" */
hlipka	0:8b387bed54c2	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
hlipka	0:8b387bed54c2	312	TCP_STATS_INC(tcp.drop);
hlipka	0:8b387bed54c2	313	snmp_inc_tcpinerrs();
hlipka	0:8b387bed54c2	314	pbuf_free(p);
hlipka	0:8b387bed54c2	315	return;
hlipka	0:8b387bed54c2	316	}
hlipka	0:8b387bed54c2	317	}
hlipka	0:8b387bed54c2	318	tcp_input_pcb = pcb;
hlipka	0:8b387bed54c2	319	err = tcp_process(pcb);
hlipka	0:8b387bed54c2	320	/* A return value of ERR_ABRT means that tcp_abort() was called
hlipka	0:8b387bed54c2	321	and that the pcb has been freed. If so, we don't do anything. */
hlipka	0:8b387bed54c2	322	if (err != ERR_ABRT) {
hlipka	0:8b387bed54c2	323	if (recv_flags & TF_RESET) {
hlipka	0:8b387bed54c2	324	/* TF_RESET means that the connection was reset by the other
hlipka	0:8b387bed54c2	325	end. We then call the error callback to inform the
hlipka	0:8b387bed54c2	326	application that the connection is dead before we
hlipka	0:8b387bed54c2	327	deallocate the PCB. */
hlipka	0:8b387bed54c2	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
hlipka	0:8b387bed54c2	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
hlipka	0:8b387bed54c2	330	memp_free(MEMP_TCP_PCB, pcb);
hlipka	0:8b387bed54c2	331	} else if (recv_flags & TF_CLOSED) {
hlipka	0:8b387bed54c2	332	/* The connection has been closed and we will deallocate the
hlipka	0:8b387bed54c2	333	PCB. */
hlipka	0:8b387bed54c2	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
hlipka	0:8b387bed54c2	335	memp_free(MEMP_TCP_PCB, pcb);
hlipka	0:8b387bed54c2	336	} else {
hlipka	0:8b387bed54c2	337	err = ERR_OK;
hlipka	0:8b387bed54c2	338	/* If the application has registered a "sent" function to be
hlipka	0:8b387bed54c2	339	called when new send buffer space is available, we call it
hlipka	0:8b387bed54c2	340	now. */
hlipka	0:8b387bed54c2	341	if (pcb->acked > 0) {
hlipka	0:8b387bed54c2	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
hlipka	0:8b387bed54c2	343	if (err == ERR_ABRT) {
hlipka	0:8b387bed54c2	344	goto aborted;
hlipka	0:8b387bed54c2	345	}
hlipka	0:8b387bed54c2	346	}
hlipka	0:8b387bed54c2	347
hlipka	0:8b387bed54c2	348	if (recv_data != NULL) {
hlipka	0:8b387bed54c2	349	if (pcb->flags & TF_RXCLOSED) {
hlipka	0:8b387bed54c2	350	/* received data although already closed -> abort (send RST) to
hlipka	0:8b387bed54c2	351	notify the remote host that not all data has been processed */
hlipka	0:8b387bed54c2	352	pbuf_free(recv_data);
hlipka	0:8b387bed54c2	353	tcp_abort(pcb);
hlipka	0:8b387bed54c2	354	goto aborted;
hlipka	0:8b387bed54c2	355	}
hlipka	0:8b387bed54c2	356	if (flags & TCP_PSH) {
hlipka	0:8b387bed54c2	357	recv_data->flags \|= PBUF_FLAG_PUSH;
hlipka	0:8b387bed54c2	358	}
hlipka	0:8b387bed54c2	359
hlipka	0:8b387bed54c2	360	/* Notify application that data has been received. */
hlipka	0:8b387bed54c2	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
hlipka	0:8b387bed54c2	362	if (err == ERR_ABRT) {
hlipka	0:8b387bed54c2	363	goto aborted;
hlipka	0:8b387bed54c2	364	}
hlipka	0:8b387bed54c2	365
hlipka	0:8b387bed54c2	366	/* If the upper layer can't receive this data, store it */
hlipka	0:8b387bed54c2	367	if (err != ERR_OK) {
hlipka	0:8b387bed54c2	368	pcb->refused_data = recv_data;
hlipka	0:8b387bed54c2	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
hlipka	0:8b387bed54c2	370	}
hlipka	0:8b387bed54c2	371	}
hlipka	0:8b387bed54c2	372
hlipka	0:8b387bed54c2	373	/* If a FIN segment was received, we call the callback
hlipka	0:8b387bed54c2	374	function with a NULL buffer to indicate EOF. */
hlipka	0:8b387bed54c2	375	if (recv_flags & TF_GOT_FIN) {
hlipka	0:8b387bed54c2	376	/* correct rcv_wnd as the application won't call tcp_recved()
hlipka	0:8b387bed54c2	377	for the FIN's seqno */
hlipka	0:8b387bed54c2	378	if (pcb->rcv_wnd != TCP_WND) {
hlipka	0:8b387bed54c2	379	pcb->rcv_wnd++;
hlipka	0:8b387bed54c2	380	}
hlipka	0:8b387bed54c2	381	TCP_EVENT_CLOSED(pcb, err);
hlipka	0:8b387bed54c2	382	if (err == ERR_ABRT) {
hlipka	0:8b387bed54c2	383	goto aborted;
hlipka	0:8b387bed54c2	384	}
hlipka	0:8b387bed54c2	385	}
hlipka	0:8b387bed54c2	386
hlipka	0:8b387bed54c2	387	tcp_input_pcb = NULL;
hlipka	0:8b387bed54c2	388	/* Try to send something out. */
hlipka	0:8b387bed54c2	389	tcp_output(pcb);
hlipka	0:8b387bed54c2	390	#if TCP_INPUT_DEBUG
hlipka	0:8b387bed54c2	391	#if TCP_DEBUG
hlipka	0:8b387bed54c2	392	tcp_debug_print_state(pcb->state);
hlipka	0:8b387bed54c2	393	#endif /* TCP_DEBUG */
hlipka	0:8b387bed54c2	394	#endif /* TCP_INPUT_DEBUG */
hlipka	0:8b387bed54c2	395	}
hlipka	0:8b387bed54c2	396	}
hlipka	0:8b387bed54c2	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
hlipka	0:8b387bed54c2	398	Below this line, 'pcb' may not be dereferenced! */
hlipka	0:8b387bed54c2	399	aborted:
hlipka	0:8b387bed54c2	400	tcp_input_pcb = NULL;
hlipka	0:8b387bed54c2	401	recv_data = NULL;
hlipka	0:8b387bed54c2	402
hlipka	0:8b387bed54c2	403	/* give up our reference to inseg.p */
hlipka	0:8b387bed54c2	404	if (inseg.p != NULL)
hlipka	0:8b387bed54c2	405	{
hlipka	0:8b387bed54c2	406	pbuf_free(inseg.p);
hlipka	0:8b387bed54c2	407	inseg.p = NULL;
hlipka	0:8b387bed54c2	408	}
hlipka	0:8b387bed54c2	409	} else {
hlipka	0:8b387bed54c2	410
hlipka	0:8b387bed54c2	411	/* If no matching PCB was found, send a TCP RST (reset) to the
hlipka	0:8b387bed54c2	412	sender. */
hlipka	0:8b387bed54c2	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
hlipka	0:8b387bed54c2	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
hlipka	0:8b387bed54c2	415	TCP_STATS_INC(tcp.proterr);
hlipka	0:8b387bed54c2	416	TCP_STATS_INC(tcp.drop);
hlipka	0:8b387bed54c2	417	tcp_rst(ackno, seqno + tcplen,
hlipka	0:8b387bed54c2	418	ip_current_dest_addr(), ip_current_src_addr(),
hlipka	0:8b387bed54c2	419	tcphdr->dest, tcphdr->src);
hlipka	0:8b387bed54c2	420	}
hlipka	0:8b387bed54c2	421	pbuf_free(p);
hlipka	0:8b387bed54c2	422	}
hlipka	0:8b387bed54c2	423
hlipka	0:8b387bed54c2	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
hlipka	0:8b387bed54c2	425	PERF_STOP("tcp_input");
hlipka	0:8b387bed54c2	426	}
hlipka	0:8b387bed54c2	427
hlipka	0:8b387bed54c2	428	/**
hlipka	0:8b387bed54c2	429	* Called by tcp_input() when a segment arrives for a listening
hlipka	0:8b387bed54c2	430	* connection (from tcp_input()).
hlipka	0:8b387bed54c2	431	*
hlipka	0:8b387bed54c2	432	* @param pcb the tcp_pcb_listen for which a segment arrived
hlipka	0:8b387bed54c2	433	* @return ERR_OK if the segment was processed
hlipka	0:8b387bed54c2	434	* another err_t on error
hlipka	0:8b387bed54c2	435	*
hlipka	0:8b387bed54c2	436	* @note the return value is not (yet?) used in tcp_input()
hlipka	0:8b387bed54c2	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
hlipka	0:8b387bed54c2	438	* involved is passed as a parameter to this function
hlipka	0:8b387bed54c2	439	*/
hlipka	0:8b387bed54c2	440	static err_t
hlipka	0:8b387bed54c2	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
hlipka	0:8b387bed54c2	442	{
hlipka	0:8b387bed54c2	443	struct tcp_pcb *npcb;
hlipka	0:8b387bed54c2	444	err_t rc;
hlipka	0:8b387bed54c2	445
hlipka	0:8b387bed54c2	446	/* In the LISTEN state, we check for incoming SYN segments,
hlipka	0:8b387bed54c2	447	creates a new PCB, and responds with a SYN\|ACK. */
hlipka	0:8b387bed54c2	448	if (flags & TCP_ACK) {
hlipka	0:8b387bed54c2	449	/* For incoming segments with the ACK flag set, respond with a
hlipka	0:8b387bed54c2	450	RST. */
hlipka	0:8b387bed54c2	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
hlipka	0:8b387bed54c2	452	tcp_rst(ackno + 1, seqno + tcplen,
hlipka	0:8b387bed54c2	453	ip_current_dest_addr(), ip_current_src_addr(),
hlipka	0:8b387bed54c2	454	tcphdr->dest, tcphdr->src);
hlipka	0:8b387bed54c2	455	} else if (flags & TCP_SYN) {
hlipka	0:8b387bed54c2	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
hlipka	0:8b387bed54c2	457	#if TCP_LISTEN_BACKLOG
hlipka	0:8b387bed54c2	458	if (pcb->accepts_pending >= pcb->backlog) {
hlipka	0:8b387bed54c2	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
hlipka	0:8b387bed54c2	460	return ERR_ABRT;
hlipka	0:8b387bed54c2	461	}
hlipka	0:8b387bed54c2	462	#endif /* TCP_LISTEN_BACKLOG */
hlipka	0:8b387bed54c2	463	npcb = tcp_alloc(pcb->prio);
hlipka	0:8b387bed54c2	464	/* If a new PCB could not be created (probably due to lack of memory),
hlipka	0:8b387bed54c2	465	we don't do anything, but rely on the sender will retransmit the
hlipka	0:8b387bed54c2	466	SYN at a time when we have more memory available. */
hlipka	0:8b387bed54c2	467	if (npcb == NULL) {
hlipka	0:8b387bed54c2	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
hlipka	0:8b387bed54c2	469	TCP_STATS_INC(tcp.memerr);
hlipka	0:8b387bed54c2	470	return ERR_MEM;
hlipka	0:8b387bed54c2	471	}
hlipka	0:8b387bed54c2	472	#if TCP_LISTEN_BACKLOG
hlipka	0:8b387bed54c2	473	pcb->accepts_pending++;
hlipka	0:8b387bed54c2	474	#endif /* TCP_LISTEN_BACKLOG */
hlipka	0:8b387bed54c2	475	/* Set up the new PCB. */
hlipka	0:8b387bed54c2	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
hlipka	0:8b387bed54c2	477	npcb->local_port = pcb->local_port;
hlipka	0:8b387bed54c2	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
hlipka	0:8b387bed54c2	479	npcb->remote_port = tcphdr->src;
hlipka	0:8b387bed54c2	480	npcb->state = SYN_RCVD;
hlipka	0:8b387bed54c2	481	npcb->rcv_nxt = seqno + 1;
hlipka	0:8b387bed54c2	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
hlipka	0:8b387bed54c2	483	npcb->snd_wnd = tcphdr->wnd;
hlipka	0:8b387bed54c2	484	npcb->ssthresh = npcb->snd_wnd;
hlipka	0:8b387bed54c2	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
hlipka	0:8b387bed54c2	486	npcb->callback_arg = pcb->callback_arg;
hlipka	0:8b387bed54c2	487	#if LWIP_CALLBACK_API
hlipka	0:8b387bed54c2	488	npcb->accept = pcb->accept;
hlipka	0:8b387bed54c2	489	#endif /* LWIP_CALLBACK_API */
hlipka	0:8b387bed54c2	490	/* inherit socket options */
hlipka	0:8b387bed54c2	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
hlipka	0:8b387bed54c2	492	/* Register the new PCB so that we can begin receiving segments
hlipka	0:8b387bed54c2	493	for it. */
hlipka	0:8b387bed54c2	494	TCP_REG(&tcp_active_pcbs, npcb);
hlipka	0:8b387bed54c2	495
hlipka	0:8b387bed54c2	496	/* Parse any options in the SYN. */
hlipka	0:8b387bed54c2	497	tcp_parseopt(npcb);
hlipka	0:8b387bed54c2	498	#if TCP_CALCULATE_EFF_SEND_MSS
hlipka	0:8b387bed54c2	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
hlipka	0:8b387bed54c2	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
hlipka	0:8b387bed54c2	501
hlipka	0:8b387bed54c2	502	snmp_inc_tcppassiveopens();
hlipka	0:8b387bed54c2	503
hlipka	0:8b387bed54c2	504	/* Send a SYN\|ACK together with the MSS option. */
hlipka	0:8b387bed54c2	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
hlipka	0:8b387bed54c2	506	if (rc != ERR_OK) {
hlipka	0:8b387bed54c2	507	tcp_abandon(npcb, 0);
hlipka	0:8b387bed54c2	508	return rc;
hlipka	0:8b387bed54c2	509	}
hlipka	0:8b387bed54c2	510	return tcp_output(npcb);
hlipka	0:8b387bed54c2	511	}
hlipka	0:8b387bed54c2	512	return ERR_OK;
hlipka	0:8b387bed54c2	513	}
hlipka	0:8b387bed54c2	514
hlipka	0:8b387bed54c2	515	/**
hlipka	0:8b387bed54c2	516	* Called by tcp_input() when a segment arrives for a connection in
hlipka	0:8b387bed54c2	517	* TIME_WAIT.
hlipka	0:8b387bed54c2	518	*
hlipka	0:8b387bed54c2	519	* @param pcb the tcp_pcb for which a segment arrived
hlipka	0:8b387bed54c2	520	*
hlipka	0:8b387bed54c2	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
hlipka	0:8b387bed54c2	522	* involved is passed as a parameter to this function
hlipka	0:8b387bed54c2	523	*/
hlipka	0:8b387bed54c2	524	static err_t
hlipka	0:8b387bed54c2	525	tcp_timewait_input(struct tcp_pcb *pcb)
hlipka	0:8b387bed54c2	526	{
hlipka	0:8b387bed54c2	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
hlipka	0:8b387bed54c2	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
hlipka	0:8b387bed54c2	529	* - first check sequence number - we skip that one in TIME_WAIT (always
hlipka	0:8b387bed54c2	530	* acceptable since we only send ACKs)
hlipka	0:8b387bed54c2	531	* - second check the RST bit (... return) */
hlipka	0:8b387bed54c2	532	if (flags & TCP_RST) {
hlipka	0:8b387bed54c2	533	return ERR_OK;
hlipka	0:8b387bed54c2	534	}
hlipka	0:8b387bed54c2	535	/* - fourth, check the SYN bit, */
hlipka	0:8b387bed54c2	536	if (flags & TCP_SYN) {
hlipka	0:8b387bed54c2	537	/* If an incoming segment is not acceptable, an acknowledgment
hlipka	0:8b387bed54c2	538	should be sent in reply */
hlipka	0:8b387bed54c2	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
hlipka	0:8b387bed54c2	540	/* If the SYN is in the window it is an error, send a reset */
hlipka	0:8b387bed54c2	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
hlipka	0:8b387bed54c2	542	tcphdr->dest, tcphdr->src);
hlipka	0:8b387bed54c2	543	return ERR_OK;
hlipka	0:8b387bed54c2	544	}
hlipka	0:8b387bed54c2	545	} else if (flags & TCP_FIN) {
hlipka	0:8b387bed54c2	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
hlipka	0:8b387bed54c2	547	Restart the 2 MSL time-wait timeout.*/
hlipka	0:8b387bed54c2	548	pcb->tmr = tcp_ticks;
hlipka	0:8b387bed54c2	549	}
hlipka	0:8b387bed54c2	550
hlipka	0:8b387bed54c2	551	if ((tcplen > 0)) {
hlipka	0:8b387bed54c2	552	/* Acknowledge data, FIN or out-of-window SYN */
hlipka	0:8b387bed54c2	553	pcb->flags \|= TF_ACK_NOW;
hlipka	0:8b387bed54c2	554	return tcp_output(pcb);
hlipka	0:8b387bed54c2	555	}
hlipka	0:8b387bed54c2	556	return ERR_OK;
hlipka	0:8b387bed54c2	557	}
hlipka	0:8b387bed54c2	558
hlipka	0:8b387bed54c2	559	/**
hlipka	0:8b387bed54c2	560	* Implements the TCP state machine. Called by tcp_input. In some
hlipka	0:8b387bed54c2	561	* states tcp_receive() is called to receive data. The tcp_seg
hlipka	0:8b387bed54c2	562	* argument will be freed by the caller (tcp_input()) unless the
hlipka	0:8b387bed54c2	563	* recv_data pointer in the pcb is set.
hlipka	0:8b387bed54c2	564	*
hlipka	0:8b387bed54c2	565	* @param pcb the tcp_pcb for which a segment arrived
hlipka	0:8b387bed54c2	566	*
hlipka	0:8b387bed54c2	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
hlipka	0:8b387bed54c2	568	* involved is passed as a parameter to this function
hlipka	0:8b387bed54c2	569	*/
hlipka	0:8b387bed54c2	570	static err_t
hlipka	0:8b387bed54c2	571	tcp_process(struct tcp_pcb *pcb)
hlipka	0:8b387bed54c2	572	{
hlipka	0:8b387bed54c2	573	struct tcp_seg *rseg;
hlipka	0:8b387bed54c2	574	u8_t acceptable = 0;
hlipka	0:8b387bed54c2	575	err_t err;
hlipka	0:8b387bed54c2	576
hlipka	0:8b387bed54c2	577	err = ERR_OK;
hlipka	0:8b387bed54c2	578
hlipka	0:8b387bed54c2	579	/* Process incoming RST segments. */
hlipka	0:8b387bed54c2	580	if (flags & TCP_RST) {
hlipka	0:8b387bed54c2	581	/* First, determine if the reset is acceptable. */
hlipka	0:8b387bed54c2	582	if (pcb->state == SYN_SENT) {
hlipka	0:8b387bed54c2	583	if (ackno == pcb->snd_nxt) {
hlipka	0:8b387bed54c2	584	acceptable = 1;
hlipka	0:8b387bed54c2	585	}
hlipka	0:8b387bed54c2	586	} else {
hlipka	0:8b387bed54c2	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
hlipka	0:8b387bed54c2	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
hlipka	0:8b387bed54c2	589	acceptable = 1;
hlipka	0:8b387bed54c2	590	}
hlipka	0:8b387bed54c2	591	}
hlipka	0:8b387bed54c2	592
hlipka	0:8b387bed54c2	593	if (acceptable) {
hlipka	0:8b387bed54c2	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
hlipka	0:8b387bed54c2	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
hlipka	0:8b387bed54c2	596	recv_flags \|= TF_RESET;
hlipka	0:8b387bed54c2	597	pcb->flags &= ~TF_ACK_DELAY;
hlipka	0:8b387bed54c2	598	return ERR_RST;
hlipka	0:8b387bed54c2	599	} else {
hlipka	0:8b387bed54c2	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
hlipka	0:8b387bed54c2	601	seqno, pcb->rcv_nxt));
hlipka	0:8b387bed54c2	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
hlipka	0:8b387bed54c2	603	seqno, pcb->rcv_nxt));
hlipka	0:8b387bed54c2	604	return ERR_OK;
hlipka	0:8b387bed54c2	605	}
hlipka	0:8b387bed54c2	606	}
hlipka	0:8b387bed54c2	607
hlipka	0:8b387bed54c2	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
hlipka	0:8b387bed54c2	609	/* Cope with new connection attempt after remote end crashed */
hlipka	0:8b387bed54c2	610	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	611	return ERR_OK;
hlipka	0:8b387bed54c2	612	}
hlipka	0:8b387bed54c2	613
hlipka	0:8b387bed54c2	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
hlipka	0:8b387bed54c2	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
hlipka	0:8b387bed54c2	616	pcb->tmr = tcp_ticks;
hlipka	0:8b387bed54c2	617	}
hlipka	0:8b387bed54c2	618	pcb->keep_cnt_sent = 0;
hlipka	0:8b387bed54c2	619
hlipka	0:8b387bed54c2	620	tcp_parseopt(pcb);
hlipka	0:8b387bed54c2	621
hlipka	0:8b387bed54c2	622	/* Do different things depending on the TCP state. */
hlipka	0:8b387bed54c2	623	switch (pcb->state) {
hlipka	0:8b387bed54c2	624	case SYN_SENT:
hlipka	0:8b387bed54c2	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
hlipka	0:8b387bed54c2	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
hlipka	0:8b387bed54c2	627	/* received SYN ACK with expected sequence number? */
hlipka	0:8b387bed54c2	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
hlipka	0:8b387bed54c2	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
hlipka	0:8b387bed54c2	630	pcb->snd_buf++;
hlipka	0:8b387bed54c2	631	pcb->rcv_nxt = seqno + 1;
hlipka	0:8b387bed54c2	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
hlipka	0:8b387bed54c2	633	pcb->lastack = ackno;
hlipka	0:8b387bed54c2	634	pcb->snd_wnd = tcphdr->wnd;
hlipka	0:8b387bed54c2	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
hlipka	0:8b387bed54c2	636	pcb->state = ESTABLISHED;
hlipka	0:8b387bed54c2	637
hlipka	0:8b387bed54c2	638	#if TCP_CALCULATE_EFF_SEND_MSS
hlipka	0:8b387bed54c2	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
hlipka	0:8b387bed54c2	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
hlipka	0:8b387bed54c2	641
hlipka	0:8b387bed54c2	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
hlipka	0:8b387bed54c2	643	* but for the default value of pcb->mss) */
hlipka	0:8b387bed54c2	644	pcb->ssthresh = pcb->mss * 10;
hlipka	0:8b387bed54c2	645
hlipka	0:8b387bed54c2	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
hlipka	0:8b387bed54c2	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
hlipka	0:8b387bed54c2	648	--pcb->snd_queuelen;
hlipka	0:8b387bed54c2	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
hlipka	0:8b387bed54c2	650	rseg = pcb->unacked;
hlipka	0:8b387bed54c2	651	pcb->unacked = rseg->next;
hlipka	0:8b387bed54c2	652
hlipka	0:8b387bed54c2	653	/* If there's nothing left to acknowledge, stop the retransmit
hlipka	0:8b387bed54c2	654	timer, otherwise reset it to start again */
hlipka	0:8b387bed54c2	655	if(pcb->unacked == NULL)
hlipka	0:8b387bed54c2	656	pcb->rtime = -1;
hlipka	0:8b387bed54c2	657	else {
hlipka	0:8b387bed54c2	658	pcb->rtime = 0;
hlipka	0:8b387bed54c2	659	pcb->nrtx = 0;
hlipka	0:8b387bed54c2	660	}
hlipka	0:8b387bed54c2	661
hlipka	0:8b387bed54c2	662	tcp_seg_free(rseg);
hlipka	0:8b387bed54c2	663
hlipka	0:8b387bed54c2	664	/* Call the user specified function to call when sucessfully
hlipka	0:8b387bed54c2	665	* connected. */
hlipka	0:8b387bed54c2	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
hlipka	0:8b387bed54c2	667	if (err == ERR_ABRT) {
hlipka	0:8b387bed54c2	668	return ERR_ABRT;
hlipka	0:8b387bed54c2	669	}
hlipka	0:8b387bed54c2	670	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	671	}
hlipka	0:8b387bed54c2	672	/* received ACK? possibly a half-open connection */
hlipka	0:8b387bed54c2	673	else if (flags & TCP_ACK) {
hlipka	0:8b387bed54c2	674	/* send a RST to bring the other side in a non-synchronized state. */
hlipka	0:8b387bed54c2	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
hlipka	0:8b387bed54c2	676	tcphdr->dest, tcphdr->src);
hlipka	0:8b387bed54c2	677	}
hlipka	0:8b387bed54c2	678	break;
hlipka	0:8b387bed54c2	679	case SYN_RCVD:
hlipka	0:8b387bed54c2	680	if (flags & TCP_ACK) {
hlipka	0:8b387bed54c2	681	/* expected ACK number? */
hlipka	0:8b387bed54c2	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
hlipka	0:8b387bed54c2	683	u16_t old_cwnd;
hlipka	0:8b387bed54c2	684	pcb->state = ESTABLISHED;
hlipka	0:8b387bed54c2	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
hlipka	0:8b387bed54c2	686	#if LWIP_CALLBACK_API
hlipka	0:8b387bed54c2	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
hlipka	0:8b387bed54c2	688	#endif
hlipka	0:8b387bed54c2	689	/* Call the accept function. */
hlipka	0:8b387bed54c2	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
hlipka	0:8b387bed54c2	691	if (err != ERR_OK) {
hlipka	0:8b387bed54c2	692	/* If the accept function returns with an error, we abort
hlipka	0:8b387bed54c2	693	* the connection. */
hlipka	0:8b387bed54c2	694	/* Already aborted? */
hlipka	0:8b387bed54c2	695	if (err != ERR_ABRT) {
hlipka	0:8b387bed54c2	696	tcp_abort(pcb);
hlipka	0:8b387bed54c2	697	}
hlipka	0:8b387bed54c2	698	return ERR_ABRT;
hlipka	0:8b387bed54c2	699	}
hlipka	0:8b387bed54c2	700	old_cwnd = pcb->cwnd;
hlipka	0:8b387bed54c2	701	/* If there was any data contained within this ACK,
hlipka	0:8b387bed54c2	702	* we'd better pass it on to the application as well. */
hlipka	0:8b387bed54c2	703	tcp_receive(pcb);
hlipka	0:8b387bed54c2	704
hlipka	0:8b387bed54c2	705	/* Prevent ACK for SYN to generate a sent event */
hlipka	0:8b387bed54c2	706	if (pcb->acked != 0) {
hlipka	0:8b387bed54c2	707	pcb->acked--;
hlipka	0:8b387bed54c2	708	}
hlipka	0:8b387bed54c2	709
hlipka	0:8b387bed54c2	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
hlipka	0:8b387bed54c2	711
hlipka	0:8b387bed54c2	712	if (recv_flags & TF_GOT_FIN) {
hlipka	0:8b387bed54c2	713	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	714	pcb->state = CLOSE_WAIT;
hlipka	0:8b387bed54c2	715	}
hlipka	0:8b387bed54c2	716	} else {
hlipka	0:8b387bed54c2	717	/* incorrect ACK number, send RST */
hlipka	0:8b387bed54c2	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
hlipka	0:8b387bed54c2	719	tcphdr->dest, tcphdr->src);
hlipka	0:8b387bed54c2	720	}
hlipka	0:8b387bed54c2	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
hlipka	0:8b387bed54c2	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
hlipka	0:8b387bed54c2	723	tcp_rexmit(pcb);
hlipka	0:8b387bed54c2	724	}
hlipka	0:8b387bed54c2	725	break;
hlipka	0:8b387bed54c2	726	case CLOSE_WAIT:
hlipka	0:8b387bed54c2	727	/* FALLTHROUGH */
hlipka	0:8b387bed54c2	728	case ESTABLISHED:
hlipka	0:8b387bed54c2	729	tcp_receive(pcb);
hlipka	0:8b387bed54c2	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
hlipka	0:8b387bed54c2	731	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	732	pcb->state = CLOSE_WAIT;
hlipka	0:8b387bed54c2	733	}
hlipka	0:8b387bed54c2	734	break;
hlipka	0:8b387bed54c2	735	case FIN_WAIT_1:
hlipka	0:8b387bed54c2	736	tcp_receive(pcb);
hlipka	0:8b387bed54c2	737	if (recv_flags & TF_GOT_FIN) {
hlipka	0:8b387bed54c2	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
hlipka	0:8b387bed54c2	739	LWIP_DEBUGF(TCP_DEBUG,
hlipka	0:8b387bed54c2	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
hlipka	0:8b387bed54c2	741	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	742	tcp_pcb_purge(pcb);
hlipka	0:8b387bed54c2	743	TCP_RMV(&tcp_active_pcbs, pcb);
hlipka	0:8b387bed54c2	744	pcb->state = TIME_WAIT;
hlipka	0:8b387bed54c2	745	TCP_REG(&tcp_tw_pcbs, pcb);
hlipka	0:8b387bed54c2	746	} else {
hlipka	0:8b387bed54c2	747	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	748	pcb->state = CLOSING;
hlipka	0:8b387bed54c2	749	}
hlipka	0:8b387bed54c2	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
hlipka	0:8b387bed54c2	751	pcb->state = FIN_WAIT_2;
hlipka	0:8b387bed54c2	752	}
hlipka	0:8b387bed54c2	753	break;
hlipka	0:8b387bed54c2	754	case FIN_WAIT_2:
hlipka	0:8b387bed54c2	755	tcp_receive(pcb);
hlipka	0:8b387bed54c2	756	if (recv_flags & TF_GOT_FIN) {
hlipka	0:8b387bed54c2	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
hlipka	0:8b387bed54c2	758	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	759	tcp_pcb_purge(pcb);
hlipka	0:8b387bed54c2	760	TCP_RMV(&tcp_active_pcbs, pcb);
hlipka	0:8b387bed54c2	761	pcb->state = TIME_WAIT;
hlipka	0:8b387bed54c2	762	TCP_REG(&tcp_tw_pcbs, pcb);
hlipka	0:8b387bed54c2	763	}
hlipka	0:8b387bed54c2	764	break;
hlipka	0:8b387bed54c2	765	case CLOSING:
hlipka	0:8b387bed54c2	766	tcp_receive(pcb);
hlipka	0:8b387bed54c2	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
hlipka	0:8b387bed54c2	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
hlipka	0:8b387bed54c2	769	tcp_pcb_purge(pcb);
hlipka	0:8b387bed54c2	770	TCP_RMV(&tcp_active_pcbs, pcb);
hlipka	0:8b387bed54c2	771	pcb->state = TIME_WAIT;
hlipka	0:8b387bed54c2	772	TCP_REG(&tcp_tw_pcbs, pcb);
hlipka	0:8b387bed54c2	773	}
hlipka	0:8b387bed54c2	774	break;
hlipka	0:8b387bed54c2	775	case LAST_ACK:
hlipka	0:8b387bed54c2	776	tcp_receive(pcb);
hlipka	0:8b387bed54c2	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
hlipka	0:8b387bed54c2	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
hlipka	0:8b387bed54c2	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
hlipka	0:8b387bed54c2	780	recv_flags \|= TF_CLOSED;
hlipka	0:8b387bed54c2	781	}
hlipka	0:8b387bed54c2	782	break;
hlipka	0:8b387bed54c2	783	default:
hlipka	0:8b387bed54c2	784	break;
hlipka	0:8b387bed54c2	785	}
hlipka	0:8b387bed54c2	786	return ERR_OK;
hlipka	0:8b387bed54c2	787	}
hlipka	0:8b387bed54c2	788
hlipka	0:8b387bed54c2	789	#if TCP_QUEUE_OOSEQ
hlipka	0:8b387bed54c2	790	/**
hlipka	0:8b387bed54c2	791	* Insert segment into the list (segments covered with new one will be deleted)
hlipka	0:8b387bed54c2	792	*
hlipka	0:8b387bed54c2	793	* Called from tcp_receive()
hlipka	0:8b387bed54c2	794	*/
hlipka	0:8b387bed54c2	795	static void
hlipka	0:8b387bed54c2	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
hlipka	0:8b387bed54c2	797	{
hlipka	0:8b387bed54c2	798	struct tcp_seg *old_seg;
hlipka	0:8b387bed54c2	799
hlipka	0:8b387bed54c2	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	801	/* received segment overlaps all following segments */
hlipka	0:8b387bed54c2	802	tcp_segs_free(next);
hlipka	0:8b387bed54c2	803	next = NULL;
hlipka	0:8b387bed54c2	804	}
hlipka	0:8b387bed54c2	805	else {
hlipka	0:8b387bed54c2	806	/* delete some following segments
hlipka	0:8b387bed54c2	807	oos queue may have segments with FIN flag */
hlipka	0:8b387bed54c2	808	while (next &&
hlipka	0:8b387bed54c2	809	TCP_SEQ_GEQ((seqno + cseg->len),
hlipka	0:8b387bed54c2	810	(next->tcphdr->seqno + next->len))) {
hlipka	0:8b387bed54c2	811	/* cseg with FIN already processed */
hlipka	0:8b387bed54c2	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
hlipka	0:8b387bed54c2	814	}
hlipka	0:8b387bed54c2	815	old_seg = next;
hlipka	0:8b387bed54c2	816	next = next->next;
hlipka	0:8b387bed54c2	817	tcp_seg_free(old_seg);
hlipka	0:8b387bed54c2	818	}
hlipka	0:8b387bed54c2	819	if (next &&
hlipka	0:8b387bed54c2	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
hlipka	0:8b387bed54c2	821	/* We need to trim the incoming segment. */
hlipka	0:8b387bed54c2	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
hlipka	0:8b387bed54c2	823	pbuf_realloc(cseg->p, cseg->len);
hlipka	0:8b387bed54c2	824	}
hlipka	0:8b387bed54c2	825	}
hlipka	0:8b387bed54c2	826	cseg->next = next;
hlipka	0:8b387bed54c2	827	}
hlipka	0:8b387bed54c2	828	#endif /* TCP_QUEUE_OOSEQ */
hlipka	0:8b387bed54c2	829
hlipka	0:8b387bed54c2	830	/**
hlipka	0:8b387bed54c2	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
hlipka	0:8b387bed54c2	832	* data, and if so frees the memory of the buffered data. Next, is places the
hlipka	0:8b387bed54c2	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
hlipka	0:8b387bed54c2	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
hlipka	0:8b387bed54c2	835	* i it has been removed from the buffer.
hlipka	0:8b387bed54c2	836	*
hlipka	0:8b387bed54c2	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
hlipka	0:8b387bed54c2	838	* estimation, the RTT is estimated here as well.
hlipka	0:8b387bed54c2	839	*
hlipka	0:8b387bed54c2	840	* Called from tcp_process().
hlipka	0:8b387bed54c2	841	*/
hlipka	0:8b387bed54c2	842	static void
hlipka	0:8b387bed54c2	843	tcp_receive(struct tcp_pcb *pcb)
hlipka	0:8b387bed54c2	844	{
hlipka	0:8b387bed54c2	845	struct tcp_seg *next;
hlipka	0:8b387bed54c2	846	#if TCP_QUEUE_OOSEQ
hlipka	0:8b387bed54c2	847	struct tcp_seg prev, cseg;
hlipka	0:8b387bed54c2	848	#endif /* TCP_QUEUE_OOSEQ */
hlipka	0:8b387bed54c2	849	struct pbuf *p;
hlipka	0:8b387bed54c2	850	s32_t off;
hlipka	0:8b387bed54c2	851	s16_t m;
hlipka	0:8b387bed54c2	852	u32_t right_wnd_edge;
hlipka	0:8b387bed54c2	853	u16_t new_tot_len;
hlipka	0:8b387bed54c2	854	int found_dupack = 0;
hlipka	0:8b387bed54c2	855
hlipka	0:8b387bed54c2	856	if (flags & TCP_ACK) {
hlipka	0:8b387bed54c2	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
hlipka	0:8b387bed54c2	858
hlipka	0:8b387bed54c2	859	/* Update window. */
hlipka	0:8b387bed54c2	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
hlipka	0:8b387bed54c2	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
hlipka	0:8b387bed54c2	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
hlipka	0:8b387bed54c2	863	pcb->snd_wnd = tcphdr->wnd;
hlipka	0:8b387bed54c2	864	pcb->snd_wl1 = seqno;
hlipka	0:8b387bed54c2	865	pcb->snd_wl2 = ackno;
hlipka	0:8b387bed54c2	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
hlipka	0:8b387bed54c2	867	pcb->persist_backoff = 0;
hlipka	0:8b387bed54c2	868	}
hlipka	0:8b387bed54c2	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
hlipka	0:8b387bed54c2	870	#if TCP_WND_DEBUG
hlipka	0:8b387bed54c2	871	} else {
hlipka	0:8b387bed54c2	872	if (pcb->snd_wnd != tcphdr->wnd) {
hlipka	0:8b387bed54c2	873	LWIP_DEBUGF(TCP_WND_DEBUG,
hlipka	0:8b387bed54c2	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
hlipka	0:8b387bed54c2	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
hlipka	0:8b387bed54c2	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
hlipka	0:8b387bed54c2	877	}
hlipka	0:8b387bed54c2	878	#endif /* TCP_WND_DEBUG */
hlipka	0:8b387bed54c2	879	}
hlipka	0:8b387bed54c2	880
hlipka	0:8b387bed54c2	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
hlipka	0:8b387bed54c2	882	* duplicate ack if:
hlipka	0:8b387bed54c2	883	* 1) It doesn't ACK new data
hlipka	0:8b387bed54c2	884	* 2) length of received packet is zero (i.e. no payload)
hlipka	0:8b387bed54c2	885	* 3) the advertised window hasn't changed
hlipka	0:8b387bed54c2	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
hlipka	0:8b387bed54c2	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
hlipka	0:8b387bed54c2	888	*
hlipka	0:8b387bed54c2	889	* If it passes all five, should process as a dupack:
hlipka	0:8b387bed54c2	890	* a) dupacks < 3: do nothing
hlipka	0:8b387bed54c2	891	* b) dupacks == 3: fast retransmit
hlipka	0:8b387bed54c2	892	* c) dupacks > 3: increase cwnd
hlipka	0:8b387bed54c2	893	*
hlipka	0:8b387bed54c2	894	* If it only passes 1-3, should reset dupack counter (and add to
hlipka	0:8b387bed54c2	895	* stats, which we don't do in lwIP)
hlipka	0:8b387bed54c2	896	*
hlipka	0:8b387bed54c2	897	* If it only passes 1, should reset dupack counter
hlipka	0:8b387bed54c2	898	*
hlipka	0:8b387bed54c2	899	*/
hlipka	0:8b387bed54c2	900
hlipka	0:8b387bed54c2	901	/* Clause 1 */
hlipka	0:8b387bed54c2	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
hlipka	0:8b387bed54c2	903	pcb->acked = 0;
hlipka	0:8b387bed54c2	904	/* Clause 2 */
hlipka	0:8b387bed54c2	905	if (tcplen == 0) {
hlipka	0:8b387bed54c2	906	/* Clause 3 */
hlipka	0:8b387bed54c2	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
hlipka	0:8b387bed54c2	908	/* Clause 4 */
hlipka	0:8b387bed54c2	909	if (pcb->rtime >= 0) {
hlipka	0:8b387bed54c2	910	/* Clause 5 */
hlipka	0:8b387bed54c2	911	if (pcb->lastack == ackno) {
hlipka	0:8b387bed54c2	912	found_dupack = 1;
hlipka	0:8b387bed54c2	913	if (pcb->dupacks + 1 > pcb->dupacks)
hlipka	0:8b387bed54c2	914	++pcb->dupacks;
hlipka	0:8b387bed54c2	915	if (pcb->dupacks > 3) {
hlipka	0:8b387bed54c2	916	/* Inflate the congestion window, but not if it means that
hlipka	0:8b387bed54c2	917	the value overflows. */
hlipka	0:8b387bed54c2	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
hlipka	0:8b387bed54c2	919	pcb->cwnd += pcb->mss;
hlipka	0:8b387bed54c2	920	}
hlipka	0:8b387bed54c2	921	} else if (pcb->dupacks == 3) {
hlipka	0:8b387bed54c2	922	/* Do fast retransmit */
hlipka	0:8b387bed54c2	923	tcp_rexmit_fast(pcb);
hlipka	0:8b387bed54c2	924	}
hlipka	0:8b387bed54c2	925	}
hlipka	0:8b387bed54c2	926	}
hlipka	0:8b387bed54c2	927	}
hlipka	0:8b387bed54c2	928	}
hlipka	0:8b387bed54c2	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
hlipka	0:8b387bed54c2	930	* count of consecutive duplicate acks */
hlipka	0:8b387bed54c2	931	if (!found_dupack) {
hlipka	0:8b387bed54c2	932	pcb->dupacks = 0;
hlipka	0:8b387bed54c2	933	}
hlipka	0:8b387bed54c2	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
hlipka	0:8b387bed54c2	935	/* We come here when the ACK acknowledges new data. */
hlipka	0:8b387bed54c2	936
hlipka	0:8b387bed54c2	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
hlipka	0:8b387bed54c2	938	in fast retransmit. Also reset the congestion window to the
hlipka	0:8b387bed54c2	939	slow start threshold. */
hlipka	0:8b387bed54c2	940	if (pcb->flags & TF_INFR) {
hlipka	0:8b387bed54c2	941	pcb->flags &= ~TF_INFR;
hlipka	0:8b387bed54c2	942	pcb->cwnd = pcb->ssthresh;
hlipka	0:8b387bed54c2	943	}
hlipka	0:8b387bed54c2	944
hlipka	0:8b387bed54c2	945	/* Reset the number of retransmissions. */
hlipka	0:8b387bed54c2	946	pcb->nrtx = 0;
hlipka	0:8b387bed54c2	947
hlipka	0:8b387bed54c2	948	/* Reset the retransmission time-out. */
hlipka	0:8b387bed54c2	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
hlipka	0:8b387bed54c2	950
hlipka	0:8b387bed54c2	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
hlipka	0:8b387bed54c2	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
hlipka	0:8b387bed54c2	953
hlipka	0:8b387bed54c2	954	pcb->snd_buf += pcb->acked;
hlipka	0:8b387bed54c2	955
hlipka	0:8b387bed54c2	956	/* Reset the fast retransmit variables. */
hlipka	0:8b387bed54c2	957	pcb->dupacks = 0;
hlipka	0:8b387bed54c2	958	pcb->lastack = ackno;
hlipka	0:8b387bed54c2	959
hlipka	0:8b387bed54c2	960	/* Update the congestion control variables (cwnd and
hlipka	0:8b387bed54c2	961	ssthresh). */
hlipka	0:8b387bed54c2	962	if (pcb->state >= ESTABLISHED) {
hlipka	0:8b387bed54c2	963	if (pcb->cwnd < pcb->ssthresh) {
hlipka	0:8b387bed54c2	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
hlipka	0:8b387bed54c2	965	pcb->cwnd += pcb->mss;
hlipka	0:8b387bed54c2	966	}
hlipka	0:8b387bed54c2	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
hlipka	0:8b387bed54c2	968	} else {
hlipka	0:8b387bed54c2	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
hlipka	0:8b387bed54c2	970	if (new_cwnd > pcb->cwnd) {
hlipka	0:8b387bed54c2	971	pcb->cwnd = new_cwnd;
hlipka	0:8b387bed54c2	972	}
hlipka	0:8b387bed54c2	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
hlipka	0:8b387bed54c2	974	}
hlipka	0:8b387bed54c2	975	}
hlipka	0:8b387bed54c2	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
hlipka	0:8b387bed54c2	977	ackno,
hlipka	0:8b387bed54c2	978	pcb->unacked != NULL?
hlipka	0:8b387bed54c2	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
hlipka	0:8b387bed54c2	980	pcb->unacked != NULL?
hlipka	0:8b387bed54c2	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
hlipka	0:8b387bed54c2	982
hlipka	0:8b387bed54c2	983	/* Remove segment from the unacknowledged list if the incoming
hlipka	0:8b387bed54c2	984	ACK acknowlegdes them. */
hlipka	0:8b387bed54c2	985	while (pcb->unacked != NULL &&
hlipka	0:8b387bed54c2	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
hlipka	0:8b387bed54c2	987	TCP_TCPLEN(pcb->unacked), ackno)) {
hlipka	0:8b387bed54c2	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
hlipka	0:8b387bed54c2	989	ntohl(pcb->unacked->tcphdr->seqno),
hlipka	0:8b387bed54c2	990	ntohl(pcb->unacked->tcphdr->seqno) +
hlipka	0:8b387bed54c2	991	TCP_TCPLEN(pcb->unacked)));
hlipka	0:8b387bed54c2	992
hlipka	0:8b387bed54c2	993	next = pcb->unacked;
hlipka	0:8b387bed54c2	994	pcb->unacked = pcb->unacked->next;
hlipka	0:8b387bed54c2	995
hlipka	0:8b387bed54c2	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
hlipka	0:8b387bed54c2	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
hlipka	0:8b387bed54c2	998	/* Prevent ACK for FIN to generate a sent event */
hlipka	0:8b387bed54c2	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
hlipka	0:8b387bed54c2	1000	pcb->acked--;
hlipka	0:8b387bed54c2	1001	}
hlipka	0:8b387bed54c2	1002
hlipka	0:8b387bed54c2	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
hlipka	0:8b387bed54c2	1004	tcp_seg_free(next);
hlipka	0:8b387bed54c2	1005
hlipka	0:8b387bed54c2	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
hlipka	0:8b387bed54c2	1007	if (pcb->snd_queuelen != 0) {
hlipka	0:8b387bed54c2	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
hlipka	0:8b387bed54c2	1009	pcb->unsent != NULL);
hlipka	0:8b387bed54c2	1010	}
hlipka	0:8b387bed54c2	1011	}
hlipka	0:8b387bed54c2	1012
hlipka	0:8b387bed54c2	1013	/* If there's nothing left to acknowledge, stop the retransmit
hlipka	0:8b387bed54c2	1014	timer, otherwise reset it to start again */
hlipka	0:8b387bed54c2	1015	if(pcb->unacked == NULL)
hlipka	0:8b387bed54c2	1016	pcb->rtime = -1;
hlipka	0:8b387bed54c2	1017	else
hlipka	0:8b387bed54c2	1018	pcb->rtime = 0;
hlipka	0:8b387bed54c2	1019
hlipka	0:8b387bed54c2	1020	pcb->polltmr = 0;
hlipka	0:8b387bed54c2	1021	} else {
hlipka	0:8b387bed54c2	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
hlipka	0:8b387bed54c2	1023	pcb->acked = 0;
hlipka	0:8b387bed54c2	1024	}
hlipka	0:8b387bed54c2	1025
hlipka	0:8b387bed54c2	1026	/* We go through the ->unsent list to see if any of the segments
hlipka	0:8b387bed54c2	1027	on the list are acknowledged by the ACK. This may seem
hlipka	0:8b387bed54c2	1028	strange since an "unsent" segment shouldn't be acked. The
hlipka	0:8b387bed54c2	1029	rationale is that lwIP puts all outstanding segments on the
hlipka	0:8b387bed54c2	1030	->unsent list after a retransmission, so these segments may
hlipka	0:8b387bed54c2	1031	in fact have been sent once. */
hlipka	0:8b387bed54c2	1032	while (pcb->unsent != NULL &&
hlipka	0:8b387bed54c2	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
hlipka	0:8b387bed54c2	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
hlipka	0:8b387bed54c2	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
hlipka	0:8b387bed54c2	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
hlipka	0:8b387bed54c2	1037	TCP_TCPLEN(pcb->unsent)));
hlipka	0:8b387bed54c2	1038
hlipka	0:8b387bed54c2	1039	next = pcb->unsent;
hlipka	0:8b387bed54c2	1040	pcb->unsent = pcb->unsent->next;
hlipka	0:8b387bed54c2	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
hlipka	0:8b387bed54c2	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
hlipka	0:8b387bed54c2	1043	/* Prevent ACK for FIN to generate a sent event */
hlipka	0:8b387bed54c2	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
hlipka	0:8b387bed54c2	1045	pcb->acked--;
hlipka	0:8b387bed54c2	1046	}
hlipka	0:8b387bed54c2	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
hlipka	0:8b387bed54c2	1048	tcp_seg_free(next);
hlipka	0:8b387bed54c2	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
hlipka	0:8b387bed54c2	1050	if (pcb->snd_queuelen != 0) {
hlipka	0:8b387bed54c2	1051	LWIP_ASSERT("tcp_receive: valid queue length",
hlipka	0:8b387bed54c2	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
hlipka	0:8b387bed54c2	1053	}
hlipka	0:8b387bed54c2	1054	}
hlipka	0:8b387bed54c2	1055	/* End of ACK for new data processing. */
hlipka	0:8b387bed54c2	1056
hlipka	0:8b387bed54c2	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
hlipka	0:8b387bed54c2	1058	pcb->rttest, pcb->rtseq, ackno));
hlipka	0:8b387bed54c2	1059
hlipka	0:8b387bed54c2	1060	/* RTT estimation calculations. This is done by checking if the
hlipka	0:8b387bed54c2	1061	incoming segment acknowledges the segment we use to take a
hlipka	0:8b387bed54c2	1062	round-trip time measurement. */
hlipka	0:8b387bed54c2	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
hlipka	0:8b387bed54c2	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
hlipka	0:8b387bed54c2	1065	and a round-trip shouldn't be that long... */
hlipka	0:8b387bed54c2	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
hlipka	0:8b387bed54c2	1067
hlipka	0:8b387bed54c2	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
hlipka	0:8b387bed54c2	1069	m, m * TCP_SLOW_INTERVAL));
hlipka	0:8b387bed54c2	1070
hlipka	0:8b387bed54c2	1071	/* This is taken directly from VJs original code in his paper */
hlipka	0:8b387bed54c2	1072	m = m - (pcb->sa >> 3);
hlipka	0:8b387bed54c2	1073	pcb->sa += m;
hlipka	0:8b387bed54c2	1074	if (m < 0) {
hlipka	0:8b387bed54c2	1075	m = -m;
hlipka	0:8b387bed54c2	1076	}
hlipka	0:8b387bed54c2	1077	m = m - (pcb->sv >> 2);
hlipka	0:8b387bed54c2	1078	pcb->sv += m;
hlipka	0:8b387bed54c2	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
hlipka	0:8b387bed54c2	1080
hlipka	0:8b387bed54c2	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
hlipka	0:8b387bed54c2	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
hlipka	0:8b387bed54c2	1083
hlipka	0:8b387bed54c2	1084	pcb->rttest = 0;
hlipka	0:8b387bed54c2	1085	}
hlipka	0:8b387bed54c2	1086	}
hlipka	0:8b387bed54c2	1087
hlipka	0:8b387bed54c2	1088	/* If the incoming segment contains data, we must process it
hlipka	0:8b387bed54c2	1089	further. */
hlipka	0:8b387bed54c2	1090	if (tcplen > 0) {
hlipka	0:8b387bed54c2	1091	/* This code basically does three things:
hlipka	0:8b387bed54c2	1092
hlipka	0:8b387bed54c2	1093	+) If the incoming segment contains data that is the next
hlipka	0:8b387bed54c2	1094	in-sequence data, this data is passed to the application. This
hlipka	0:8b387bed54c2	1095	might involve trimming the first edge of the data. The rcv_nxt
hlipka	0:8b387bed54c2	1096	variable and the advertised window are adjusted.
hlipka	0:8b387bed54c2	1097
hlipka	0:8b387bed54c2	1098	+) If the incoming segment has data that is above the next
hlipka	0:8b387bed54c2	1099	sequence number expected (->rcv_nxt), the segment is placed on
hlipka	0:8b387bed54c2	1100	the ->ooseq queue. This is done by finding the appropriate
hlipka	0:8b387bed54c2	1101	place in the ->ooseq queue (which is ordered by sequence
hlipka	0:8b387bed54c2	1102	number) and trim the segment in both ends if needed. An
hlipka	0:8b387bed54c2	1103	immediate ACK is sent to indicate that we received an
hlipka	0:8b387bed54c2	1104	out-of-sequence segment.
hlipka	0:8b387bed54c2	1105
hlipka	0:8b387bed54c2	1106	+) Finally, we check if the first segment on the ->ooseq queue
hlipka	0:8b387bed54c2	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
hlipka	0:8b387bed54c2	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
hlipka	0:8b387bed54c2	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
hlipka	0:8b387bed54c2	1110	segments that are now on sequence are chained onto the
hlipka	0:8b387bed54c2	1111	incoming segment so that we only need to call the application
hlipka	0:8b387bed54c2	1112	once.
hlipka	0:8b387bed54c2	1113	*/
hlipka	0:8b387bed54c2	1114
hlipka	0:8b387bed54c2	1115	/* First, we check if we must trim the first edge. We have to do
hlipka	0:8b387bed54c2	1116	this if the sequence number of the incoming segment is less
hlipka	0:8b387bed54c2	1117	than rcv_nxt, and the sequence number plus the length of the
hlipka	0:8b387bed54c2	1118	segment is larger than rcv_nxt. */
hlipka	0:8b387bed54c2	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
hlipka	0:8b387bed54c2	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
hlipka	0:8b387bed54c2	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
hlipka	0:8b387bed54c2	1122	/* Trimming the first edge is done by pushing the payload
hlipka	0:8b387bed54c2	1123	pointer in the pbuf downwards. This is somewhat tricky since
hlipka	0:8b387bed54c2	1124	we do not want to discard the full contents of the pbuf up to
hlipka	0:8b387bed54c2	1125	the new starting point of the data since we have to keep the
hlipka	0:8b387bed54c2	1126	TCP header which is present in the first pbuf in the chain.
hlipka	0:8b387bed54c2	1127
hlipka	0:8b387bed54c2	1128	What is done is really quite a nasty hack: the first pbuf in
hlipka	0:8b387bed54c2	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
hlipka	0:8b387bed54c2	1130	able to deallocate the whole pbuf, we cannot change this
hlipka	0:8b387bed54c2	1131	inseg.p pointer to point to any of the later pbufs in the
hlipka	0:8b387bed54c2	1132	chain. Instead, we point the ->payload pointer in the first
hlipka	0:8b387bed54c2	1133	pbuf to data in one of the later pbufs. We also set the
hlipka	0:8b387bed54c2	1134	inseg.data pointer to point to the right place. This way, the
hlipka	0:8b387bed54c2	1135	->p pointer will still point to the first pbuf, but the
hlipka	0:8b387bed54c2	1136	->p->payload pointer will point to data in another pbuf.
hlipka	0:8b387bed54c2	1137
hlipka	0:8b387bed54c2	1138	After we are done with adjusting the pbuf pointers we must
hlipka	0:8b387bed54c2	1139	adjust the ->data pointer in the seg and the segment
hlipka	0:8b387bed54c2	1140	length.*/
hlipka	0:8b387bed54c2	1141
hlipka	0:8b387bed54c2	1142	off = pcb->rcv_nxt - seqno;
hlipka	0:8b387bed54c2	1143	p = inseg.p;
hlipka	0:8b387bed54c2	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
hlipka	0:8b387bed54c2	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
hlipka	0:8b387bed54c2	1146	if (inseg.p->len < off) {
hlipka	0:8b387bed54c2	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
hlipka	0:8b387bed54c2	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
hlipka	0:8b387bed54c2	1149	while (p->len < off) {
hlipka	0:8b387bed54c2	1150	off -= p->len;
hlipka	0:8b387bed54c2	1151	/* KJM following line changed (with addition of new_tot_len var)
hlipka	0:8b387bed54c2	1152	to fix bug #9076
hlipka	0:8b387bed54c2	1153	inseg.p->tot_len -= p->len; */
hlipka	0:8b387bed54c2	1154	p->tot_len = new_tot_len;
hlipka	0:8b387bed54c2	1155	p->len = 0;
hlipka	0:8b387bed54c2	1156	p = p->next;
hlipka	0:8b387bed54c2	1157	}
hlipka	0:8b387bed54c2	1158	if(pbuf_header(p, (s16_t)-off)) {
hlipka	0:8b387bed54c2	1159	/* Do we need to cope with this failing? Assert for now */
hlipka	0:8b387bed54c2	1160	LWIP_ASSERT("pbuf_header failed", 0);
hlipka	0:8b387bed54c2	1161	}
hlipka	0:8b387bed54c2	1162	} else {
hlipka	0:8b387bed54c2	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
hlipka	0:8b387bed54c2	1164	/* Do we need to cope with this failing? Assert for now */
hlipka	0:8b387bed54c2	1165	LWIP_ASSERT("pbuf_header failed", 0);
hlipka	0:8b387bed54c2	1166	}
hlipka	0:8b387bed54c2	1167	}
hlipka	0:8b387bed54c2	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
hlipka	0:8b387bed54c2	1169	to fix bug #9076 */
hlipka	0:8b387bed54c2	1170	inseg.dataptr = p->payload;
hlipka	0:8b387bed54c2	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
hlipka	0:8b387bed54c2	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
hlipka	0:8b387bed54c2	1173	}
hlipka	0:8b387bed54c2	1174	else {
hlipka	0:8b387bed54c2	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
hlipka	0:8b387bed54c2	1176	/* the whole segment is < rcv_nxt */
hlipka	0:8b387bed54c2	1177	/* must be a duplicate of a packet that has already been correctly handled */
hlipka	0:8b387bed54c2	1178
hlipka	0:8b387bed54c2	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
hlipka	0:8b387bed54c2	1180	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	1181	}
hlipka	0:8b387bed54c2	1182	}
hlipka	0:8b387bed54c2	1183
hlipka	0:8b387bed54c2	1184	/* The sequence number must be within the window (above rcv_nxt
hlipka	0:8b387bed54c2	1185	and below rcv_nxt + rcv_wnd) in order to be further
hlipka	0:8b387bed54c2	1186	processed. */
hlipka	0:8b387bed54c2	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
hlipka	0:8b387bed54c2	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
hlipka	0:8b387bed54c2	1189	if (pcb->rcv_nxt == seqno) {
hlipka	0:8b387bed54c2	1190	/* The incoming segment is the next in sequence. We check if
hlipka	0:8b387bed54c2	1191	we have to trim the end of the segment and update rcv_nxt
hlipka	0:8b387bed54c2	1192	and pass the data to the application. */
hlipka	0:8b387bed54c2	1193	tcplen = TCP_TCPLEN(&inseg);
hlipka	0:8b387bed54c2	1194
hlipka	0:8b387bed54c2	1195	if (tcplen > pcb->rcv_wnd) {
hlipka	0:8b387bed54c2	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
hlipka	0:8b387bed54c2	1197	("tcp_receive: other end overran receive window"
hlipka	0:8b387bed54c2	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
hlipka	0:8b387bed54c2	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
hlipka	0:8b387bed54c2	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	1201	/* Must remove the FIN from the header as we're trimming
hlipka	0:8b387bed54c2	1202	* that byte of sequence-space from the packet */
hlipka	0:8b387bed54c2	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
hlipka	0:8b387bed54c2	1204	}
hlipka	0:8b387bed54c2	1205	/* Adjust length of segment to fit in the window. */
hlipka	0:8b387bed54c2	1206	inseg.len = pcb->rcv_wnd;
hlipka	0:8b387bed54c2	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
hlipka	0:8b387bed54c2	1208	inseg.len -= 1;
hlipka	0:8b387bed54c2	1209	}
hlipka	0:8b387bed54c2	1210	pbuf_realloc(inseg.p, inseg.len);
hlipka	0:8b387bed54c2	1211	tcplen = TCP_TCPLEN(&inseg);
hlipka	0:8b387bed54c2	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
hlipka	0:8b387bed54c2	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
hlipka	0:8b387bed54c2	1214	}
hlipka	0:8b387bed54c2	1215	#if TCP_QUEUE_OOSEQ
hlipka	0:8b387bed54c2	1216	/* Received in-sequence data, adjust ooseq data if:
hlipka	0:8b387bed54c2	1217	- FIN has been received or
hlipka	0:8b387bed54c2	1218	- inseq overlaps with ooseq */
hlipka	0:8b387bed54c2	1219	if (pcb->ooseq != NULL) {
hlipka	0:8b387bed54c2	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
hlipka	0:8b387bed54c2	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
hlipka	0:8b387bed54c2	1223	/* Received in-order FIN means anything that was received
hlipka	0:8b387bed54c2	1224	* out of order must now have been received in-order, so
hlipka	0:8b387bed54c2	1225	* bin the ooseq queue */
hlipka	0:8b387bed54c2	1226	while (pcb->ooseq != NULL) {
hlipka	0:8b387bed54c2	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
hlipka	0:8b387bed54c2	1228	pcb->ooseq = pcb->ooseq->next;
hlipka	0:8b387bed54c2	1229	tcp_seg_free(old_ooseq);
hlipka	0:8b387bed54c2	1230	}
hlipka	0:8b387bed54c2	1231	}
hlipka	0:8b387bed54c2	1232	else {
hlipka	0:8b387bed54c2	1233	next = pcb->ooseq;
hlipka	0:8b387bed54c2	1234	/* Remove all segments on ooseq that are covered by inseg already.
hlipka	0:8b387bed54c2	1235	* FIN is copied from ooseq to inseg if present. */
hlipka	0:8b387bed54c2	1236	while (next &&
hlipka	0:8b387bed54c2	1237	TCP_SEQ_GEQ(seqno + tcplen,
hlipka	0:8b387bed54c2	1238	next->tcphdr->seqno + next->len)) {
hlipka	0:8b387bed54c2	1239	/* inseg cannot have FIN here (already processed above) */
hlipka	0:8b387bed54c2	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
hlipka	0:8b387bed54c2	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
hlipka	0:8b387bed54c2	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
hlipka	0:8b387bed54c2	1243	tcplen = TCP_TCPLEN(&inseg);
hlipka	0:8b387bed54c2	1244	}
hlipka	0:8b387bed54c2	1245	prev = next;
hlipka	0:8b387bed54c2	1246	next = next->next;
hlipka	0:8b387bed54c2	1247	tcp_seg_free(prev);
hlipka	0:8b387bed54c2	1248	}
hlipka	0:8b387bed54c2	1249	/* Now trim right side of inseg if it overlaps with the first
hlipka	0:8b387bed54c2	1250	* segment on ooseq */
hlipka	0:8b387bed54c2	1251	if (next &&
hlipka	0:8b387bed54c2	1252	TCP_SEQ_GT(seqno + tcplen,
hlipka	0:8b387bed54c2	1253	next->tcphdr->seqno)) {
hlipka	0:8b387bed54c2	1254	/* inseg cannot have FIN here (already processed above) */
hlipka	0:8b387bed54c2	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
hlipka	0:8b387bed54c2	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
hlipka	0:8b387bed54c2	1257	inseg.len -= 1;
hlipka	0:8b387bed54c2	1258	}
hlipka	0:8b387bed54c2	1259	pbuf_realloc(inseg.p, inseg.len);
hlipka	0:8b387bed54c2	1260	tcplen = TCP_TCPLEN(&inseg);
hlipka	0:8b387bed54c2	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
hlipka	0:8b387bed54c2	1262	(seqno + tcplen) == next->tcphdr->seqno);
hlipka	0:8b387bed54c2	1263	}
hlipka	0:8b387bed54c2	1264	pcb->ooseq = next;
hlipka	0:8b387bed54c2	1265	}
hlipka	0:8b387bed54c2	1266	}
hlipka	0:8b387bed54c2	1267	#endif /* TCP_QUEUE_OOSEQ */
hlipka	0:8b387bed54c2	1268
hlipka	0:8b387bed54c2	1269	pcb->rcv_nxt = seqno + tcplen;
hlipka	0:8b387bed54c2	1270
hlipka	0:8b387bed54c2	1271	/* Update the receiver's (our) window. */
hlipka	0:8b387bed54c2	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
hlipka	0:8b387bed54c2	1273	pcb->rcv_wnd -= tcplen;
hlipka	0:8b387bed54c2	1274
hlipka	0:8b387bed54c2	1275	tcp_update_rcv_ann_wnd(pcb);
hlipka	0:8b387bed54c2	1276
hlipka	0:8b387bed54c2	1277	/* If there is data in the segment, we make preparations to
hlipka	0:8b387bed54c2	1278	pass this up to the application. The ->recv_data variable
hlipka	0:8b387bed54c2	1279	is used for holding the pbuf that goes to the
hlipka	0:8b387bed54c2	1280	application. The code for reassembling out-of-sequence data
hlipka	0:8b387bed54c2	1281	chains its data on this pbuf as well.
hlipka	0:8b387bed54c2	1282
hlipka	0:8b387bed54c2	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
hlipka	0:8b387bed54c2	1284	be used to indicate to the application that the remote side has
hlipka	0:8b387bed54c2	1285	closed its end of the connection. */
hlipka	0:8b387bed54c2	1286	if (inseg.p->tot_len > 0) {
hlipka	0:8b387bed54c2	1287	recv_data = inseg.p;
hlipka	0:8b387bed54c2	1288	/* Since this pbuf now is the responsibility of the
hlipka	0:8b387bed54c2	1289	application, we delete our reference to it so that we won't
hlipka	0:8b387bed54c2	1290	(mistakingly) deallocate it. */
hlipka	0:8b387bed54c2	1291	inseg.p = NULL;
hlipka	0:8b387bed54c2	1292	}
hlipka	0:8b387bed54c2	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
hlipka	0:8b387bed54c2	1295	recv_flags \|= TF_GOT_FIN;
hlipka	0:8b387bed54c2	1296	}
hlipka	0:8b387bed54c2	1297
hlipka	0:8b387bed54c2	1298	#if TCP_QUEUE_OOSEQ
hlipka	0:8b387bed54c2	1299	/* We now check if we have segments on the ->ooseq queue that
hlipka	0:8b387bed54c2	1300	are now in sequence. */
hlipka	0:8b387bed54c2	1301	while (pcb->ooseq != NULL &&
hlipka	0:8b387bed54c2	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
hlipka	0:8b387bed54c2	1303
hlipka	0:8b387bed54c2	1304	cseg = pcb->ooseq;
hlipka	0:8b387bed54c2	1305	seqno = pcb->ooseq->tcphdr->seqno;
hlipka	0:8b387bed54c2	1306
hlipka	0:8b387bed54c2	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
hlipka	0:8b387bed54c2	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
hlipka	0:8b387bed54c2	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
hlipka	0:8b387bed54c2	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
hlipka	0:8b387bed54c2	1311
hlipka	0:8b387bed54c2	1312	tcp_update_rcv_ann_wnd(pcb);
hlipka	0:8b387bed54c2	1313
hlipka	0:8b387bed54c2	1314	if (cseg->p->tot_len > 0) {
hlipka	0:8b387bed54c2	1315	/* Chain this pbuf onto the pbuf that we will pass to
hlipka	0:8b387bed54c2	1316	the application. */
hlipka	0:8b387bed54c2	1317	if (recv_data) {
hlipka	0:8b387bed54c2	1318	pbuf_cat(recv_data, cseg->p);
hlipka	0:8b387bed54c2	1319	} else {
hlipka	0:8b387bed54c2	1320	recv_data = cseg->p;
hlipka	0:8b387bed54c2	1321	}
hlipka	0:8b387bed54c2	1322	cseg->p = NULL;
hlipka	0:8b387bed54c2	1323	}
hlipka	0:8b387bed54c2	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
hlipka	0:8b387bed54c2	1326	recv_flags \|= TF_GOT_FIN;
hlipka	0:8b387bed54c2	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
hlipka	0:8b387bed54c2	1328	pcb->state = CLOSE_WAIT;
hlipka	0:8b387bed54c2	1329	}
hlipka	0:8b387bed54c2	1330	}
hlipka	0:8b387bed54c2	1331
hlipka	0:8b387bed54c2	1332	pcb->ooseq = cseg->next;
hlipka	0:8b387bed54c2	1333	tcp_seg_free(cseg);
hlipka	0:8b387bed54c2	1334	}
hlipka	0:8b387bed54c2	1335	#endif /* TCP_QUEUE_OOSEQ */
hlipka	0:8b387bed54c2	1336
hlipka	0:8b387bed54c2	1337
hlipka	0:8b387bed54c2	1338	/* Acknowledge the segment(s). */
hlipka	0:8b387bed54c2	1339	tcp_ack(pcb);
hlipka	0:8b387bed54c2	1340
hlipka	0:8b387bed54c2	1341	} else {
hlipka	0:8b387bed54c2	1342	/* We get here if the incoming segment is out-of-sequence. */
hlipka	0:8b387bed54c2	1343	tcp_send_empty_ack(pcb);
hlipka	0:8b387bed54c2	1344	#if TCP_QUEUE_OOSEQ
hlipka	0:8b387bed54c2	1345	/* We queue the segment on the ->ooseq queue. */
hlipka	0:8b387bed54c2	1346	if (pcb->ooseq == NULL) {
hlipka	0:8b387bed54c2	1347	pcb->ooseq = tcp_seg_copy(&inseg);
hlipka	0:8b387bed54c2	1348	} else {
hlipka	0:8b387bed54c2	1349	/* If the queue is not empty, we walk through the queue and
hlipka	0:8b387bed54c2	1350	try to find a place where the sequence number of the
hlipka	0:8b387bed54c2	1351	incoming segment is between the sequence numbers of the
hlipka	0:8b387bed54c2	1352	previous and the next segment on the ->ooseq queue. That is
hlipka	0:8b387bed54c2	1353	the place where we put the incoming segment. If needed, we
hlipka	0:8b387bed54c2	1354	trim the second edges of the previous and the incoming
hlipka	0:8b387bed54c2	1355	segment so that it will fit into the sequence.
hlipka	0:8b387bed54c2	1356
hlipka	0:8b387bed54c2	1357	If the incoming segment has the same sequence number as a
hlipka	0:8b387bed54c2	1358	segment on the ->ooseq queue, we discard the segment that
hlipka	0:8b387bed54c2	1359	contains less data. */
hlipka	0:8b387bed54c2	1360
hlipka	0:8b387bed54c2	1361	prev = NULL;
hlipka	0:8b387bed54c2	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
hlipka	0:8b387bed54c2	1363	if (seqno == next->tcphdr->seqno) {
hlipka	0:8b387bed54c2	1364	/* The sequence number of the incoming segment is the
hlipka	0:8b387bed54c2	1365	same as the sequence number of the segment on
hlipka	0:8b387bed54c2	1366	->ooseq. We check the lengths to see which one to
hlipka	0:8b387bed54c2	1367	discard. */
hlipka	0:8b387bed54c2	1368	if (inseg.len > next->len) {
hlipka	0:8b387bed54c2	1369	/* The incoming segment is larger than the old
hlipka	0:8b387bed54c2	1370	segment. We replace some segments with the new
hlipka	0:8b387bed54c2	1371	one. */
hlipka	0:8b387bed54c2	1372	cseg = tcp_seg_copy(&inseg);
hlipka	0:8b387bed54c2	1373	if (cseg != NULL) {
hlipka	0:8b387bed54c2	1374	if (prev != NULL) {
hlipka	0:8b387bed54c2	1375	prev->next = cseg;
hlipka	0:8b387bed54c2	1376	} else {
hlipka	0:8b387bed54c2	1377	pcb->ooseq = cseg;
hlipka	0:8b387bed54c2	1378	}
hlipka	0:8b387bed54c2	1379	tcp_oos_insert_segment(cseg, next);
hlipka	0:8b387bed54c2	1380	}
hlipka	0:8b387bed54c2	1381	break;
hlipka	0:8b387bed54c2	1382	} else {
hlipka	0:8b387bed54c2	1383	/* Either the lenghts are the same or the incoming
hlipka	0:8b387bed54c2	1384	segment was smaller than the old one; in either
hlipka	0:8b387bed54c2	1385	case, we ditch the incoming segment. */
hlipka	0:8b387bed54c2	1386	break;
hlipka	0:8b387bed54c2	1387	}
hlipka	0:8b387bed54c2	1388	} else {
hlipka	0:8b387bed54c2	1389	if (prev == NULL) {
hlipka	0:8b387bed54c2	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
hlipka	0:8b387bed54c2	1391	/* The sequence number of the incoming segment is lower
hlipka	0:8b387bed54c2	1392	than the sequence number of the first segment on the
hlipka	0:8b387bed54c2	1393	queue. We put the incoming segment first on the
hlipka	0:8b387bed54c2	1394	queue. */
hlipka	0:8b387bed54c2	1395	cseg = tcp_seg_copy(&inseg);
hlipka	0:8b387bed54c2	1396	if (cseg != NULL) {
hlipka	0:8b387bed54c2	1397	pcb->ooseq = cseg;
hlipka	0:8b387bed54c2	1398	tcp_oos_insert_segment(cseg, next);
hlipka	0:8b387bed54c2	1399	}
hlipka	0:8b387bed54c2	1400	break;
hlipka	0:8b387bed54c2	1401	}
hlipka	0:8b387bed54c2	1402	} else {
hlipka	0:8b387bed54c2	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
hlipka	0:8b387bed54c2	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
hlipka	0:8b387bed54c2	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
hlipka	0:8b387bed54c2	1406	/* The sequence number of the incoming segment is in
hlipka	0:8b387bed54c2	1407	between the sequence numbers of the previous and
hlipka	0:8b387bed54c2	1408	the next segment on ->ooseq. We trim trim the previous
hlipka	0:8b387bed54c2	1409	segment, delete next segments that included in received segment
hlipka	0:8b387bed54c2	1410	and trim received, if needed. */
hlipka	0:8b387bed54c2	1411	cseg = tcp_seg_copy(&inseg);
hlipka	0:8b387bed54c2	1412	if (cseg != NULL) {
hlipka	0:8b387bed54c2	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
hlipka	0:8b387bed54c2	1414	/* We need to trim the prev segment. */
hlipka	0:8b387bed54c2	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
hlipka	0:8b387bed54c2	1416	pbuf_realloc(prev->p, prev->len);
hlipka	0:8b387bed54c2	1417	}
hlipka	0:8b387bed54c2	1418	prev->next = cseg;
hlipka	0:8b387bed54c2	1419	tcp_oos_insert_segment(cseg, next);
hlipka	0:8b387bed54c2	1420	}
hlipka	0:8b387bed54c2	1421	break;
hlipka	0:8b387bed54c2	1422	}
hlipka	0:8b387bed54c2	1423	}
hlipka	0:8b387bed54c2	1424	/* If the "next" segment is the last segment on the
hlipka	0:8b387bed54c2	1425	ooseq queue, we add the incoming segment to the end
hlipka	0:8b387bed54c2	1426	of the list. */
hlipka	0:8b387bed54c2	1427	if (next->next == NULL &&
hlipka	0:8b387bed54c2	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
hlipka	0:8b387bed54c2	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	1430	/* segment "next" already contains all data */
hlipka	0:8b387bed54c2	1431	break;
hlipka	0:8b387bed54c2	1432	}
hlipka	0:8b387bed54c2	1433	next->next = tcp_seg_copy(&inseg);
hlipka	0:8b387bed54c2	1434	if (next->next != NULL) {
hlipka	0:8b387bed54c2	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
hlipka	0:8b387bed54c2	1436	/* We need to trim the last segment. */
hlipka	0:8b387bed54c2	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
hlipka	0:8b387bed54c2	1438	pbuf_realloc(next->p, next->len);
hlipka	0:8b387bed54c2	1439	}
hlipka	0:8b387bed54c2	1440	/* check if the remote side overruns our receive window */
hlipka	0:8b387bed54c2	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
hlipka	0:8b387bed54c2	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
hlipka	0:8b387bed54c2	1443	("tcp_receive: other end overran receive window"
hlipka	0:8b387bed54c2	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
hlipka	0:8b387bed54c2	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
hlipka	0:8b387bed54c2	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
hlipka	0:8b387bed54c2	1447	/* Must remove the FIN from the header as we're trimming
hlipka	0:8b387bed54c2	1448	* that byte of sequence-space from the packet */
hlipka	0:8b387bed54c2	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
hlipka	0:8b387bed54c2	1450	}
hlipka	0:8b387bed54c2	1451	/* Adjust length of segment to fit in the window. */
hlipka	0:8b387bed54c2	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
hlipka	0:8b387bed54c2	1453	pbuf_realloc(next->next->p, next->next->len);
hlipka	0:8b387bed54c2	1454	tcplen = TCP_TCPLEN(next->next);
hlipka	0:8b387bed54c2	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
hlipka	0:8b387bed54c2	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
hlipka	0:8b387bed54c2	1457	}
hlipka	0:8b387bed54c2	1458	}
hlipka	0:8b387bed54c2	1459	break;
hlipka	0:8b387bed54c2	1460	}
hlipka	0:8b387bed54c2	1461	}
hlipka	0:8b387bed54c2	1462	prev = next;
hlipka	0:8b387bed54c2	1463	}
hlipka	0:8b387bed54c2	1464	}
hlipka	0:8b387bed54c2	1465	#endif /* TCP_QUEUE_OOSEQ */
hlipka	0:8b387bed54c2	1466
hlipka	0:8b387bed54c2	1467	}
hlipka	0:8b387bed54c2	1468	} else {
hlipka	0:8b387bed54c2	1469	/* The incoming segment is not withing the window. */
hlipka	0:8b387bed54c2	1470	tcp_send_empty_ack(pcb);
hlipka	0:8b387bed54c2	1471	}
hlipka	0:8b387bed54c2	1472	} else {
hlipka	0:8b387bed54c2	1473	/* Segments with length 0 is taken care of here. Segments that
hlipka	0:8b387bed54c2	1474	fall out of the window are ACKed. */
hlipka	0:8b387bed54c2	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
hlipka	0:8b387bed54c2	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
hlipka	0:8b387bed54c2	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
hlipka	0:8b387bed54c2	1478	tcp_ack_now(pcb);
hlipka	0:8b387bed54c2	1479	}
hlipka	0:8b387bed54c2	1480	}
hlipka	0:8b387bed54c2	1481	}
hlipka	0:8b387bed54c2	1482
hlipka	0:8b387bed54c2	1483	/**
hlipka	0:8b387bed54c2	1484	* Parses the options contained in the incoming segment.
hlipka	0:8b387bed54c2	1485	*
hlipka	0:8b387bed54c2	1486	* Called from tcp_listen_input() and tcp_process().
hlipka	0:8b387bed54c2	1487	* Currently, only the MSS option is supported!
hlipka	0:8b387bed54c2	1488	*
hlipka	0:8b387bed54c2	1489	* @param pcb the tcp_pcb for which a segment arrived
hlipka	0:8b387bed54c2	1490	*/
hlipka	0:8b387bed54c2	1491	static void
hlipka	0:8b387bed54c2	1492	tcp_parseopt(struct tcp_pcb *pcb)
hlipka	0:8b387bed54c2	1493	{
hlipka	0:8b387bed54c2	1494	u16_t c, max_c;
hlipka	0:8b387bed54c2	1495	u16_t mss;
hlipka	0:8b387bed54c2	1496	u8_t *opts, opt;
hlipka	0:8b387bed54c2	1497	#if LWIP_TCP_TIMESTAMPS
hlipka	0:8b387bed54c2	1498	u32_t tsval;
hlipka	0:8b387bed54c2	1499	#endif
hlipka	0:8b387bed54c2	1500
hlipka	0:8b387bed54c2	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
hlipka	0:8b387bed54c2	1502
hlipka	0:8b387bed54c2	1503	/* Parse the TCP MSS option, if present. */
hlipka	0:8b387bed54c2	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
hlipka	0:8b387bed54c2	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
hlipka	0:8b387bed54c2	1506	for (c = 0; c < max_c; ) {
hlipka	0:8b387bed54c2	1507	opt = opts[c];
hlipka	0:8b387bed54c2	1508	switch (opt) {
hlipka	0:8b387bed54c2	1509	case 0x00:
hlipka	0:8b387bed54c2	1510	/* End of options. */
hlipka	0:8b387bed54c2	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
hlipka	0:8b387bed54c2	1512	return;
hlipka	0:8b387bed54c2	1513	case 0x01:
hlipka	0:8b387bed54c2	1514	/* NOP option. */
hlipka	0:8b387bed54c2	1515	++c;
hlipka	0:8b387bed54c2	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
hlipka	0:8b387bed54c2	1517	break;
hlipka	0:8b387bed54c2	1518	case 0x02:
hlipka	0:8b387bed54c2	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
hlipka	0:8b387bed54c2	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
hlipka	0:8b387bed54c2	1521	/* Bad length */
hlipka	0:8b387bed54c2	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
hlipka	0:8b387bed54c2	1523	return;
hlipka	0:8b387bed54c2	1524	}
hlipka	0:8b387bed54c2	1525	/* An MSS option with the right option length. */
hlipka	0:8b387bed54c2	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
hlipka	0:8b387bed54c2	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
hlipka	0:8b387bed54c2	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
hlipka	0:8b387bed54c2	1529	/* Advance to next option */
hlipka	0:8b387bed54c2	1530	c += 0x04;
hlipka	0:8b387bed54c2	1531	break;
hlipka	0:8b387bed54c2	1532	#if LWIP_TCP_TIMESTAMPS
hlipka	0:8b387bed54c2	1533	case 0x08:
hlipka	0:8b387bed54c2	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
hlipka	0:8b387bed54c2	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
hlipka	0:8b387bed54c2	1536	/* Bad length */
hlipka	0:8b387bed54c2	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
hlipka	0:8b387bed54c2	1538	return;
hlipka	0:8b387bed54c2	1539	}
hlipka	0:8b387bed54c2	1540	/* TCP timestamp option with valid length */
hlipka	0:8b387bed54c2	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
hlipka	0:8b387bed54c2	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
hlipka	0:8b387bed54c2	1543	if (flags & TCP_SYN) {
hlipka	0:8b387bed54c2	1544	pcb->ts_recent = ntohl(tsval);
hlipka	0:8b387bed54c2	1545	pcb->flags \|= TF_TIMESTAMP;
hlipka	0:8b387bed54c2	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
hlipka	0:8b387bed54c2	1547	pcb->ts_recent = ntohl(tsval);
hlipka	0:8b387bed54c2	1548	}
hlipka	0:8b387bed54c2	1549	/* Advance to next option */
hlipka	0:8b387bed54c2	1550	c += 0x0A;
hlipka	0:8b387bed54c2	1551	break;
hlipka	0:8b387bed54c2	1552	#endif
hlipka	0:8b387bed54c2	1553	default:
hlipka	0:8b387bed54c2	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
hlipka	0:8b387bed54c2	1555	if (opts[c + 1] == 0) {
hlipka	0:8b387bed54c2	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
hlipka	0:8b387bed54c2	1557	/* If the length field is zero, the options are malformed
hlipka	0:8b387bed54c2	1558	and we don't process them further. */
hlipka	0:8b387bed54c2	1559	return;
hlipka	0:8b387bed54c2	1560	}
hlipka	0:8b387bed54c2	1561	/* All other options have a length field, so that we easily
hlipka	0:8b387bed54c2	1562	can skip past them. */
hlipka	0:8b387bed54c2	1563	c += opts[c + 1];
hlipka	0:8b387bed54c2	1564	}
hlipka	0:8b387bed54c2	1565	}
hlipka	0:8b387bed54c2	1566	}
hlipka	0:8b387bed54c2	1567	}
hlipka	0:8b387bed54c2	1568
hlipka	0:8b387bed54c2	1569	#endif /* LWIP_TCP */

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Type:	Library
Created:	10 Jan 2011
Imports:	412
Forks:	1
Commits:	2
Dependents:	9
Dependencies:	2
Followers:	6

lwip/core/tcp_in.c@0:8b387bed54c2, 2011-01-10 (annotated)

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