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This library is stripped down version of NetServices library. HTTP server and client function is NOT supported.

lwip/core/tcp_in.c@0:dcf3c92487ca, 2011-07-20 (annotated)

Committer:: idinor
Date:: Wed Jul 20 11:45:39 2011 +0000
Revision:: 0:dcf3c92487ca

Who changed what in which revision?

User	Revision	Line number	New contents of line
idinor	0:dcf3c92487ca	1	/**
idinor	0:dcf3c92487ca	2	* @file
idinor	0:dcf3c92487ca	3	* Transmission Control Protocol, incoming traffic
idinor	0:dcf3c92487ca	4	*
idinor	0:dcf3c92487ca	5	* The input processing functions of the TCP layer.
idinor	0:dcf3c92487ca	6	*
idinor	0:dcf3c92487ca	7	* These functions are generally called in the order (ip_input() ->)
idinor	0:dcf3c92487ca	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
idinor	0:dcf3c92487ca	9	*
idinor	0:dcf3c92487ca	10	*/
idinor	0:dcf3c92487ca	11
idinor	0:dcf3c92487ca	12	/*
idinor	0:dcf3c92487ca	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
idinor	0:dcf3c92487ca	14	* All rights reserved.
idinor	0:dcf3c92487ca	15	*
idinor	0:dcf3c92487ca	16	* Redistribution and use in source and binary forms, with or without modification,
idinor	0:dcf3c92487ca	17	* are permitted provided that the following conditions are met:
idinor	0:dcf3c92487ca	18	*
idinor	0:dcf3c92487ca	19	* 1. Redistributions of source code must retain the above copyright notice,
idinor	0:dcf3c92487ca	20	* this list of conditions and the following disclaimer.
idinor	0:dcf3c92487ca	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
idinor	0:dcf3c92487ca	22	* this list of conditions and the following disclaimer in the documentation
idinor	0:dcf3c92487ca	23	* and/or other materials provided with the distribution.
idinor	0:dcf3c92487ca	24	* 3. The name of the author may not be used to endorse or promote products
idinor	0:dcf3c92487ca	25	* derived from this software without specific prior written permission.
idinor	0:dcf3c92487ca	26	*
idinor	0:dcf3c92487ca	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
idinor	0:dcf3c92487ca	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
idinor	0:dcf3c92487ca	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
idinor	0:dcf3c92487ca	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
idinor	0:dcf3c92487ca	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
idinor	0:dcf3c92487ca	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
idinor	0:dcf3c92487ca	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
idinor	0:dcf3c92487ca	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
idinor	0:dcf3c92487ca	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
idinor	0:dcf3c92487ca	36	* OF SUCH DAMAGE.
idinor	0:dcf3c92487ca	37	*
idinor	0:dcf3c92487ca	38	* This file is part of the lwIP TCP/IP stack.
idinor	0:dcf3c92487ca	39	*
idinor	0:dcf3c92487ca	40	* Author: Adam Dunkels <adam@sics.se>
idinor	0:dcf3c92487ca	41	*
idinor	0:dcf3c92487ca	42	*/
idinor	0:dcf3c92487ca	43
idinor	0:dcf3c92487ca	44	#include "lwip/opt.h"
idinor	0:dcf3c92487ca	45
idinor	0:dcf3c92487ca	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
idinor	0:dcf3c92487ca	47
idinor	0:dcf3c92487ca	48	#include "lwip/tcp_impl.h"
idinor	0:dcf3c92487ca	49	#include "lwip/def.h"
idinor	0:dcf3c92487ca	50	#include "lwip/ip_addr.h"
idinor	0:dcf3c92487ca	51	#include "lwip/netif.h"
idinor	0:dcf3c92487ca	52	#include "lwip/mem.h"
idinor	0:dcf3c92487ca	53	#include "lwip/memp.h"
idinor	0:dcf3c92487ca	54	#include "lwip/inet_chksum.h"
idinor	0:dcf3c92487ca	55	#include "lwip/stats.h"
idinor	0:dcf3c92487ca	56	#include "lwip/snmp.h"
idinor	0:dcf3c92487ca	57	#include "arch/perf.h"
idinor	0:dcf3c92487ca	58
idinor	0:dcf3c92487ca	59	/* These variables are global to all functions involved in the input
idinor	0:dcf3c92487ca	60	processing of TCP segments. They are set by the tcp_input()
idinor	0:dcf3c92487ca	61	function. */
idinor	0:dcf3c92487ca	62	static struct tcp_seg inseg;
idinor	0:dcf3c92487ca	63	static struct tcp_hdr *tcphdr;
idinor	0:dcf3c92487ca	64	static struct ip_hdr *iphdr;
idinor	0:dcf3c92487ca	65	static u32_t seqno, ackno;
idinor	0:dcf3c92487ca	66	static u8_t flags;
idinor	0:dcf3c92487ca	67	static u16_t tcplen;
idinor	0:dcf3c92487ca	68
idinor	0:dcf3c92487ca	69	static u8_t recv_flags;
idinor	0:dcf3c92487ca	70	static struct pbuf *recv_data;
idinor	0:dcf3c92487ca	71
idinor	0:dcf3c92487ca	72	struct tcp_pcb *tcp_input_pcb;
idinor	0:dcf3c92487ca	73
idinor	0:dcf3c92487ca	74	/* Forward declarations. */
idinor	0:dcf3c92487ca	75	static err_t tcp_process(struct tcp_pcb *pcb);
idinor	0:dcf3c92487ca	76	static void tcp_receive(struct tcp_pcb *pcb);
idinor	0:dcf3c92487ca	77	static void tcp_parseopt(struct tcp_pcb *pcb);
idinor	0:dcf3c92487ca	78
idinor	0:dcf3c92487ca	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
idinor	0:dcf3c92487ca	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
idinor	0:dcf3c92487ca	81
idinor	0:dcf3c92487ca	82	/**
idinor	0:dcf3c92487ca	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
idinor	0:dcf3c92487ca	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
idinor	0:dcf3c92487ca	85	* the TCP finite state machine. This function is called by the IP layer (in
idinor	0:dcf3c92487ca	86	* ip_input()).
idinor	0:dcf3c92487ca	87	*
idinor	0:dcf3c92487ca	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
idinor	0:dcf3c92487ca	89	* @param inp network interface on which this segment was received
idinor	0:dcf3c92487ca	90	*/
idinor	0:dcf3c92487ca	91	void
idinor	0:dcf3c92487ca	92	tcp_input(struct pbuf p, struct netif inp)
idinor	0:dcf3c92487ca	93	{
idinor	0:dcf3c92487ca	94	struct tcp_pcb pcb, prev;
idinor	0:dcf3c92487ca	95	struct tcp_pcb_listen *lpcb;
idinor	0:dcf3c92487ca	96	#if SO_REUSE
idinor	0:dcf3c92487ca	97	struct tcp_pcb *lpcb_prev = NULL;
idinor	0:dcf3c92487ca	98	struct tcp_pcb_listen *lpcb_any = NULL;
idinor	0:dcf3c92487ca	99	#endif /* SO_REUSE */
idinor	0:dcf3c92487ca	100	u8_t hdrlen;
idinor	0:dcf3c92487ca	101	err_t err;
idinor	0:dcf3c92487ca	102
idinor	0:dcf3c92487ca	103	PERF_START;
idinor	0:dcf3c92487ca	104
idinor	0:dcf3c92487ca	105	TCP_STATS_INC(tcp.recv);
idinor	0:dcf3c92487ca	106	snmp_inc_tcpinsegs();
idinor	0:dcf3c92487ca	107
idinor	0:dcf3c92487ca	108	iphdr = (struct ip_hdr *)p->payload;
idinor	0:dcf3c92487ca	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
idinor	0:dcf3c92487ca	110
idinor	0:dcf3c92487ca	111	#if TCP_INPUT_DEBUG
idinor	0:dcf3c92487ca	112	tcp_debug_print(tcphdr);
idinor	0:dcf3c92487ca	113	#endif
idinor	0:dcf3c92487ca	114
idinor	0:dcf3c92487ca	115	/* remove header from payload */
idinor	0:dcf3c92487ca	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
idinor	0:dcf3c92487ca	117	/* drop short packets */
idinor	0:dcf3c92487ca	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
idinor	0:dcf3c92487ca	119	TCP_STATS_INC(tcp.lenerr);
idinor	0:dcf3c92487ca	120	TCP_STATS_INC(tcp.drop);
idinor	0:dcf3c92487ca	121	snmp_inc_tcpinerrs();
idinor	0:dcf3c92487ca	122	pbuf_free(p);
idinor	0:dcf3c92487ca	123	return;
idinor	0:dcf3c92487ca	124	}
idinor	0:dcf3c92487ca	125
idinor	0:dcf3c92487ca	126	/* Don't even process incoming broadcasts/multicasts. */
idinor	0:dcf3c92487ca	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
idinor	0:dcf3c92487ca	128	ip_addr_ismulticast(&current_iphdr_dest)) {
idinor	0:dcf3c92487ca	129	TCP_STATS_INC(tcp.proterr);
idinor	0:dcf3c92487ca	130	TCP_STATS_INC(tcp.drop);
idinor	0:dcf3c92487ca	131	snmp_inc_tcpinerrs();
idinor	0:dcf3c92487ca	132	pbuf_free(p);
idinor	0:dcf3c92487ca	133	return;
idinor	0:dcf3c92487ca	134	}
idinor	0:dcf3c92487ca	135
idinor	0:dcf3c92487ca	136	#if CHECKSUM_CHECK_TCP
idinor	0:dcf3c92487ca	137	/* Verify TCP checksum. */
idinor	0:dcf3c92487ca	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
idinor	0:dcf3c92487ca	139	IP_PROTO_TCP, p->tot_len) != 0) {
idinor	0:dcf3c92487ca	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
idinor	0:dcf3c92487ca	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
idinor	0:dcf3c92487ca	142	IP_PROTO_TCP, p->tot_len)));
idinor	0:dcf3c92487ca	143	#if TCP_DEBUG
idinor	0:dcf3c92487ca	144	tcp_debug_print(tcphdr);
idinor	0:dcf3c92487ca	145	#endif /* TCP_DEBUG */
idinor	0:dcf3c92487ca	146	TCP_STATS_INC(tcp.chkerr);
idinor	0:dcf3c92487ca	147	TCP_STATS_INC(tcp.drop);
idinor	0:dcf3c92487ca	148	snmp_inc_tcpinerrs();
idinor	0:dcf3c92487ca	149	pbuf_free(p);
idinor	0:dcf3c92487ca	150	return;
idinor	0:dcf3c92487ca	151	}
idinor	0:dcf3c92487ca	152	#endif
idinor	0:dcf3c92487ca	153
idinor	0:dcf3c92487ca	154	/* Move the payload pointer in the pbuf so that it points to the
idinor	0:dcf3c92487ca	155	TCP data instead of the TCP header. */
idinor	0:dcf3c92487ca	156	hdrlen = TCPH_HDRLEN(tcphdr);
idinor	0:dcf3c92487ca	157	if(pbuf_header(p, -(hdrlen * 4))){
idinor	0:dcf3c92487ca	158	/* drop short packets */
idinor	0:dcf3c92487ca	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
idinor	0:dcf3c92487ca	160	TCP_STATS_INC(tcp.lenerr);
idinor	0:dcf3c92487ca	161	TCP_STATS_INC(tcp.drop);
idinor	0:dcf3c92487ca	162	snmp_inc_tcpinerrs();
idinor	0:dcf3c92487ca	163	pbuf_free(p);
idinor	0:dcf3c92487ca	164	return;
idinor	0:dcf3c92487ca	165	}
idinor	0:dcf3c92487ca	166
idinor	0:dcf3c92487ca	167	/* Convert fields in TCP header to host byte order. */
idinor	0:dcf3c92487ca	168	tcphdr->src = ntohs(tcphdr->src);
idinor	0:dcf3c92487ca	169	tcphdr->dest = ntohs(tcphdr->dest);
idinor	0:dcf3c92487ca	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
idinor	0:dcf3c92487ca	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
idinor	0:dcf3c92487ca	172	tcphdr->wnd = ntohs(tcphdr->wnd);
idinor	0:dcf3c92487ca	173
idinor	0:dcf3c92487ca	174	flags = TCPH_FLAGS(tcphdr);
idinor	0:dcf3c92487ca	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
idinor	0:dcf3c92487ca	176
idinor	0:dcf3c92487ca	177	/* Demultiplex an incoming segment. First, we check if it is destined
idinor	0:dcf3c92487ca	178	for an active connection. */
idinor	0:dcf3c92487ca	179	prev = NULL;
idinor	0:dcf3c92487ca	180
idinor	0:dcf3c92487ca	181
idinor	0:dcf3c92487ca	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
idinor	0:dcf3c92487ca	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
idinor	0:dcf3c92487ca	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
idinor	0:dcf3c92487ca	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
idinor	0:dcf3c92487ca	186	if (pcb->remote_port == tcphdr->src &&
idinor	0:dcf3c92487ca	187	pcb->local_port == tcphdr->dest &&
idinor	0:dcf3c92487ca	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
idinor	0:dcf3c92487ca	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
idinor	0:dcf3c92487ca	190
idinor	0:dcf3c92487ca	191	/* Move this PCB to the front of the list so that subsequent
idinor	0:dcf3c92487ca	192	lookups will be faster (we exploit locality in TCP segment
idinor	0:dcf3c92487ca	193	arrivals). */
idinor	0:dcf3c92487ca	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
idinor	0:dcf3c92487ca	195	if (prev != NULL) {
idinor	0:dcf3c92487ca	196	prev->next = pcb->next;
idinor	0:dcf3c92487ca	197	pcb->next = tcp_active_pcbs;
idinor	0:dcf3c92487ca	198	tcp_active_pcbs = pcb;
idinor	0:dcf3c92487ca	199	}
idinor	0:dcf3c92487ca	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
idinor	0:dcf3c92487ca	201	break;
idinor	0:dcf3c92487ca	202	}
idinor	0:dcf3c92487ca	203	prev = pcb;
idinor	0:dcf3c92487ca	204	}
idinor	0:dcf3c92487ca	205
idinor	0:dcf3c92487ca	206	if (pcb == NULL) {
idinor	0:dcf3c92487ca	207	/* If it did not go to an active connection, we check the connections
idinor	0:dcf3c92487ca	208	in the TIME-WAIT state. */
idinor	0:dcf3c92487ca	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
idinor	0:dcf3c92487ca	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
idinor	0:dcf3c92487ca	211	if (pcb->remote_port == tcphdr->src &&
idinor	0:dcf3c92487ca	212	pcb->local_port == tcphdr->dest &&
idinor	0:dcf3c92487ca	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
idinor	0:dcf3c92487ca	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
idinor	0:dcf3c92487ca	215	/* We don't really care enough to move this PCB to the front
idinor	0:dcf3c92487ca	216	of the list since we are not very likely to receive that
idinor	0:dcf3c92487ca	217	many segments for connections in TIME-WAIT. */
idinor	0:dcf3c92487ca	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
idinor	0:dcf3c92487ca	219	tcp_timewait_input(pcb);
idinor	0:dcf3c92487ca	220	pbuf_free(p);
idinor	0:dcf3c92487ca	221	return;
idinor	0:dcf3c92487ca	222	}
idinor	0:dcf3c92487ca	223	}
idinor	0:dcf3c92487ca	224
idinor	0:dcf3c92487ca	225	/* Finally, if we still did not get a match, we check all PCBs that
idinor	0:dcf3c92487ca	226	are LISTENing for incoming connections. */
idinor	0:dcf3c92487ca	227	prev = NULL;
idinor	0:dcf3c92487ca	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
idinor	0:dcf3c92487ca	229	if (lpcb->local_port == tcphdr->dest) {
idinor	0:dcf3c92487ca	230	#if SO_REUSE
idinor	0:dcf3c92487ca	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
idinor	0:dcf3c92487ca	232	/* found an exact match */
idinor	0:dcf3c92487ca	233	break;
idinor	0:dcf3c92487ca	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
idinor	0:dcf3c92487ca	235	/* found an ANY-match */
idinor	0:dcf3c92487ca	236	lpcb_any = lpcb;
idinor	0:dcf3c92487ca	237	lpcb_prev = prev;
idinor	0:dcf3c92487ca	238	}
idinor	0:dcf3c92487ca	239	#else /* SO_REUSE */
idinor	0:dcf3c92487ca	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
idinor	0:dcf3c92487ca	241	ip_addr_isany(&(lpcb->local_ip))) {
idinor	0:dcf3c92487ca	242	/* found a match */
idinor	0:dcf3c92487ca	243	break;
idinor	0:dcf3c92487ca	244	}
idinor	0:dcf3c92487ca	245	#endif /* SO_REUSE */
idinor	0:dcf3c92487ca	246	}
idinor	0:dcf3c92487ca	247	prev = (struct tcp_pcb *)lpcb;
idinor	0:dcf3c92487ca	248	}
idinor	0:dcf3c92487ca	249	#if SO_REUSE
idinor	0:dcf3c92487ca	250	/* first try specific local IP */
idinor	0:dcf3c92487ca	251	if (lpcb == NULL) {
idinor	0:dcf3c92487ca	252	/* only pass to ANY if no specific local IP has been found */
idinor	0:dcf3c92487ca	253	lpcb = lpcb_any;
idinor	0:dcf3c92487ca	254	prev = lpcb_prev;
idinor	0:dcf3c92487ca	255	}
idinor	0:dcf3c92487ca	256	#endif /* SO_REUSE */
idinor	0:dcf3c92487ca	257	if (lpcb != NULL) {
idinor	0:dcf3c92487ca	258	/* Move this PCB to the front of the list so that subsequent
idinor	0:dcf3c92487ca	259	lookups will be faster (we exploit locality in TCP segment
idinor	0:dcf3c92487ca	260	arrivals). */
idinor	0:dcf3c92487ca	261	if (prev != NULL) {
idinor	0:dcf3c92487ca	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
idinor	0:dcf3c92487ca	263	/* our successor is the remainder of the listening list */
idinor	0:dcf3c92487ca	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
idinor	0:dcf3c92487ca	265	/* put this listening pcb at the head of the listening list */
idinor	0:dcf3c92487ca	266	tcp_listen_pcbs.listen_pcbs = lpcb;
idinor	0:dcf3c92487ca	267	}
idinor	0:dcf3c92487ca	268
idinor	0:dcf3c92487ca	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
idinor	0:dcf3c92487ca	270	tcp_listen_input(lpcb);
idinor	0:dcf3c92487ca	271	pbuf_free(p);
idinor	0:dcf3c92487ca	272	return;
idinor	0:dcf3c92487ca	273	}
idinor	0:dcf3c92487ca	274	}
idinor	0:dcf3c92487ca	275
idinor	0:dcf3c92487ca	276	#if TCP_INPUT_DEBUG
idinor	0:dcf3c92487ca	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
idinor	0:dcf3c92487ca	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
idinor	0:dcf3c92487ca	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
idinor	0:dcf3c92487ca	280	#endif /* TCP_INPUT_DEBUG */
idinor	0:dcf3c92487ca	281
idinor	0:dcf3c92487ca	282
idinor	0:dcf3c92487ca	283	if (pcb != NULL) {
idinor	0:dcf3c92487ca	284	/* The incoming segment belongs to a connection. */
idinor	0:dcf3c92487ca	285	#if TCP_INPUT_DEBUG
idinor	0:dcf3c92487ca	286	#if TCP_DEBUG
idinor	0:dcf3c92487ca	287	tcp_debug_print_state(pcb->state);
idinor	0:dcf3c92487ca	288	#endif /* TCP_DEBUG */
idinor	0:dcf3c92487ca	289	#endif /* TCP_INPUT_DEBUG */
idinor	0:dcf3c92487ca	290
idinor	0:dcf3c92487ca	291	/* Set up a tcp_seg structure. */
idinor	0:dcf3c92487ca	292	inseg.next = NULL;
idinor	0:dcf3c92487ca	293	inseg.len = p->tot_len;
idinor	0:dcf3c92487ca	294	inseg.dataptr = p->payload;
idinor	0:dcf3c92487ca	295	inseg.p = p;
idinor	0:dcf3c92487ca	296	inseg.tcphdr = tcphdr;
idinor	0:dcf3c92487ca	297
idinor	0:dcf3c92487ca	298	recv_data = NULL;
idinor	0:dcf3c92487ca	299	recv_flags = 0;
idinor	0:dcf3c92487ca	300
idinor	0:dcf3c92487ca	301	/* If there is data which was previously "refused" by upper layer */
idinor	0:dcf3c92487ca	302	if (pcb->refused_data != NULL) {
idinor	0:dcf3c92487ca	303	/* Notify again application with data previously received. */
idinor	0:dcf3c92487ca	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
idinor	0:dcf3c92487ca	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
idinor	0:dcf3c92487ca	306	if (err == ERR_OK) {
idinor	0:dcf3c92487ca	307	pcb->refused_data = NULL;
idinor	0:dcf3c92487ca	308	} else {
idinor	0:dcf3c92487ca	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
idinor	0:dcf3c92487ca	310	/* drop incoming packets, because pcb is "full" */
idinor	0:dcf3c92487ca	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
idinor	0:dcf3c92487ca	312	TCP_STATS_INC(tcp.drop);
idinor	0:dcf3c92487ca	313	snmp_inc_tcpinerrs();
idinor	0:dcf3c92487ca	314	pbuf_free(p);
idinor	0:dcf3c92487ca	315	return;
idinor	0:dcf3c92487ca	316	}
idinor	0:dcf3c92487ca	317	}
idinor	0:dcf3c92487ca	318	tcp_input_pcb = pcb;
idinor	0:dcf3c92487ca	319	err = tcp_process(pcb);
idinor	0:dcf3c92487ca	320	/* A return value of ERR_ABRT means that tcp_abort() was called
idinor	0:dcf3c92487ca	321	and that the pcb has been freed. If so, we don't do anything. */
idinor	0:dcf3c92487ca	322	if (err != ERR_ABRT) {
idinor	0:dcf3c92487ca	323	if (recv_flags & TF_RESET) {
idinor	0:dcf3c92487ca	324	/* TF_RESET means that the connection was reset by the other
idinor	0:dcf3c92487ca	325	end. We then call the error callback to inform the
idinor	0:dcf3c92487ca	326	application that the connection is dead before we
idinor	0:dcf3c92487ca	327	deallocate the PCB. */
idinor	0:dcf3c92487ca	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
idinor	0:dcf3c92487ca	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
idinor	0:dcf3c92487ca	330	memp_free(MEMP_TCP_PCB, pcb);
idinor	0:dcf3c92487ca	331	} else if (recv_flags & TF_CLOSED) {
idinor	0:dcf3c92487ca	332	/* The connection has been closed and we will deallocate the
idinor	0:dcf3c92487ca	333	PCB. */
idinor	0:dcf3c92487ca	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
idinor	0:dcf3c92487ca	335	memp_free(MEMP_TCP_PCB, pcb);
idinor	0:dcf3c92487ca	336	} else {
idinor	0:dcf3c92487ca	337	err = ERR_OK;
idinor	0:dcf3c92487ca	338	/* If the application has registered a "sent" function to be
idinor	0:dcf3c92487ca	339	called when new send buffer space is available, we call it
idinor	0:dcf3c92487ca	340	now. */
idinor	0:dcf3c92487ca	341	if (pcb->acked > 0) {
idinor	0:dcf3c92487ca	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
idinor	0:dcf3c92487ca	343	if (err == ERR_ABRT) {
idinor	0:dcf3c92487ca	344	goto aborted;
idinor	0:dcf3c92487ca	345	}
idinor	0:dcf3c92487ca	346	}
idinor	0:dcf3c92487ca	347
idinor	0:dcf3c92487ca	348	if (recv_data != NULL) {
idinor	0:dcf3c92487ca	349	if (pcb->flags & TF_RXCLOSED) {
idinor	0:dcf3c92487ca	350	/* received data although already closed -> abort (send RST) to
idinor	0:dcf3c92487ca	351	notify the remote host that not all data has been processed */
idinor	0:dcf3c92487ca	352	pbuf_free(recv_data);
idinor	0:dcf3c92487ca	353	tcp_abort(pcb);
idinor	0:dcf3c92487ca	354	goto aborted;
idinor	0:dcf3c92487ca	355	}
idinor	0:dcf3c92487ca	356	if (flags & TCP_PSH) {
idinor	0:dcf3c92487ca	357	recv_data->flags \|= PBUF_FLAG_PUSH;
idinor	0:dcf3c92487ca	358	}
idinor	0:dcf3c92487ca	359
idinor	0:dcf3c92487ca	360	/* Notify application that data has been received. */
idinor	0:dcf3c92487ca	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
idinor	0:dcf3c92487ca	362	if (err == ERR_ABRT) {
idinor	0:dcf3c92487ca	363	goto aborted;
idinor	0:dcf3c92487ca	364	}
idinor	0:dcf3c92487ca	365
idinor	0:dcf3c92487ca	366	/* If the upper layer can't receive this data, store it */
idinor	0:dcf3c92487ca	367	if (err != ERR_OK) {
idinor	0:dcf3c92487ca	368	pcb->refused_data = recv_data;
idinor	0:dcf3c92487ca	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
idinor	0:dcf3c92487ca	370	}
idinor	0:dcf3c92487ca	371	}
idinor	0:dcf3c92487ca	372
idinor	0:dcf3c92487ca	373	/* If a FIN segment was received, we call the callback
idinor	0:dcf3c92487ca	374	function with a NULL buffer to indicate EOF. */
idinor	0:dcf3c92487ca	375	if (recv_flags & TF_GOT_FIN) {
idinor	0:dcf3c92487ca	376	/* correct rcv_wnd as the application won't call tcp_recved()
idinor	0:dcf3c92487ca	377	for the FIN's seqno */
idinor	0:dcf3c92487ca	378	if (pcb->rcv_wnd != TCP_WND) {
idinor	0:dcf3c92487ca	379	pcb->rcv_wnd++;
idinor	0:dcf3c92487ca	380	}
idinor	0:dcf3c92487ca	381	TCP_EVENT_CLOSED(pcb, err);
idinor	0:dcf3c92487ca	382	if (err == ERR_ABRT) {
idinor	0:dcf3c92487ca	383	goto aborted;
idinor	0:dcf3c92487ca	384	}
idinor	0:dcf3c92487ca	385	}
idinor	0:dcf3c92487ca	386
idinor	0:dcf3c92487ca	387	tcp_input_pcb = NULL;
idinor	0:dcf3c92487ca	388	/* Try to send something out. */
idinor	0:dcf3c92487ca	389	tcp_output(pcb);
idinor	0:dcf3c92487ca	390	#if TCP_INPUT_DEBUG
idinor	0:dcf3c92487ca	391	#if TCP_DEBUG
idinor	0:dcf3c92487ca	392	tcp_debug_print_state(pcb->state);
idinor	0:dcf3c92487ca	393	#endif /* TCP_DEBUG */
idinor	0:dcf3c92487ca	394	#endif /* TCP_INPUT_DEBUG */
idinor	0:dcf3c92487ca	395	}
idinor	0:dcf3c92487ca	396	}
idinor	0:dcf3c92487ca	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
idinor	0:dcf3c92487ca	398	Below this line, 'pcb' may not be dereferenced! */
idinor	0:dcf3c92487ca	399	aborted:
idinor	0:dcf3c92487ca	400	tcp_input_pcb = NULL;
idinor	0:dcf3c92487ca	401	recv_data = NULL;
idinor	0:dcf3c92487ca	402
idinor	0:dcf3c92487ca	403	/* give up our reference to inseg.p */
idinor	0:dcf3c92487ca	404	if (inseg.p != NULL)
idinor	0:dcf3c92487ca	405	{
idinor	0:dcf3c92487ca	406	pbuf_free(inseg.p);
idinor	0:dcf3c92487ca	407	inseg.p = NULL;
idinor	0:dcf3c92487ca	408	}
idinor	0:dcf3c92487ca	409	} else {
idinor	0:dcf3c92487ca	410
idinor	0:dcf3c92487ca	411	/* If no matching PCB was found, send a TCP RST (reset) to the
idinor	0:dcf3c92487ca	412	sender. */
idinor	0:dcf3c92487ca	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
idinor	0:dcf3c92487ca	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
idinor	0:dcf3c92487ca	415	TCP_STATS_INC(tcp.proterr);
idinor	0:dcf3c92487ca	416	TCP_STATS_INC(tcp.drop);
idinor	0:dcf3c92487ca	417	tcp_rst(ackno, seqno + tcplen,
idinor	0:dcf3c92487ca	418	ip_current_dest_addr(), ip_current_src_addr(),
idinor	0:dcf3c92487ca	419	tcphdr->dest, tcphdr->src);
idinor	0:dcf3c92487ca	420	}
idinor	0:dcf3c92487ca	421	pbuf_free(p);
idinor	0:dcf3c92487ca	422	}
idinor	0:dcf3c92487ca	423
idinor	0:dcf3c92487ca	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
idinor	0:dcf3c92487ca	425	PERF_STOP("tcp_input");
idinor	0:dcf3c92487ca	426	}
idinor	0:dcf3c92487ca	427
idinor	0:dcf3c92487ca	428	/**
idinor	0:dcf3c92487ca	429	* Called by tcp_input() when a segment arrives for a listening
idinor	0:dcf3c92487ca	430	* connection (from tcp_input()).
idinor	0:dcf3c92487ca	431	*
idinor	0:dcf3c92487ca	432	* @param pcb the tcp_pcb_listen for which a segment arrived
idinor	0:dcf3c92487ca	433	* @return ERR_OK if the segment was processed
idinor	0:dcf3c92487ca	434	* another err_t on error
idinor	0:dcf3c92487ca	435	*
idinor	0:dcf3c92487ca	436	* @note the return value is not (yet?) used in tcp_input()
idinor	0:dcf3c92487ca	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
idinor	0:dcf3c92487ca	438	* involved is passed as a parameter to this function
idinor	0:dcf3c92487ca	439	*/
idinor	0:dcf3c92487ca	440	static err_t
idinor	0:dcf3c92487ca	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
idinor	0:dcf3c92487ca	442	{
idinor	0:dcf3c92487ca	443	struct tcp_pcb *npcb;
idinor	0:dcf3c92487ca	444	err_t rc;
idinor	0:dcf3c92487ca	445
idinor	0:dcf3c92487ca	446	/* In the LISTEN state, we check for incoming SYN segments,
idinor	0:dcf3c92487ca	447	creates a new PCB, and responds with a SYN\|ACK. */
idinor	0:dcf3c92487ca	448	if (flags & TCP_ACK) {
idinor	0:dcf3c92487ca	449	/* For incoming segments with the ACK flag set, respond with a
idinor	0:dcf3c92487ca	450	RST. */
idinor	0:dcf3c92487ca	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
idinor	0:dcf3c92487ca	452	tcp_rst(ackno + 1, seqno + tcplen,
idinor	0:dcf3c92487ca	453	ip_current_dest_addr(), ip_current_src_addr(),
idinor	0:dcf3c92487ca	454	tcphdr->dest, tcphdr->src);
idinor	0:dcf3c92487ca	455	} else if (flags & TCP_SYN) {
idinor	0:dcf3c92487ca	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
idinor	0:dcf3c92487ca	457	#if TCP_LISTEN_BACKLOG
idinor	0:dcf3c92487ca	458	if (pcb->accepts_pending >= pcb->backlog) {
idinor	0:dcf3c92487ca	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
idinor	0:dcf3c92487ca	460	return ERR_ABRT;
idinor	0:dcf3c92487ca	461	}
idinor	0:dcf3c92487ca	462	#endif /* TCP_LISTEN_BACKLOG */
idinor	0:dcf3c92487ca	463	npcb = tcp_alloc(pcb->prio);
idinor	0:dcf3c92487ca	464	/* If a new PCB could not be created (probably due to lack of memory),
idinor	0:dcf3c92487ca	465	we don't do anything, but rely on the sender will retransmit the
idinor	0:dcf3c92487ca	466	SYN at a time when we have more memory available. */
idinor	0:dcf3c92487ca	467	if (npcb == NULL) {
idinor	0:dcf3c92487ca	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
idinor	0:dcf3c92487ca	469	TCP_STATS_INC(tcp.memerr);
idinor	0:dcf3c92487ca	470	return ERR_MEM;
idinor	0:dcf3c92487ca	471	}
idinor	0:dcf3c92487ca	472	#if TCP_LISTEN_BACKLOG
idinor	0:dcf3c92487ca	473	pcb->accepts_pending++;
idinor	0:dcf3c92487ca	474	#endif /* TCP_LISTEN_BACKLOG */
idinor	0:dcf3c92487ca	475	/* Set up the new PCB. */
idinor	0:dcf3c92487ca	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
idinor	0:dcf3c92487ca	477	npcb->local_port = pcb->local_port;
idinor	0:dcf3c92487ca	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
idinor	0:dcf3c92487ca	479	npcb->remote_port = tcphdr->src;
idinor	0:dcf3c92487ca	480	npcb->state = SYN_RCVD;
idinor	0:dcf3c92487ca	481	npcb->rcv_nxt = seqno + 1;
idinor	0:dcf3c92487ca	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
idinor	0:dcf3c92487ca	483	npcb->snd_wnd = tcphdr->wnd;
idinor	0:dcf3c92487ca	484	npcb->ssthresh = npcb->snd_wnd;
idinor	0:dcf3c92487ca	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
idinor	0:dcf3c92487ca	486	npcb->callback_arg = pcb->callback_arg;
idinor	0:dcf3c92487ca	487	#if LWIP_CALLBACK_API
idinor	0:dcf3c92487ca	488	npcb->accept = pcb->accept;
idinor	0:dcf3c92487ca	489	#endif /* LWIP_CALLBACK_API */
idinor	0:dcf3c92487ca	490	/* inherit socket options */
idinor	0:dcf3c92487ca	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
idinor	0:dcf3c92487ca	492	/* Register the new PCB so that we can begin receiving segments
idinor	0:dcf3c92487ca	493	for it. */
idinor	0:dcf3c92487ca	494	TCP_REG(&tcp_active_pcbs, npcb);
idinor	0:dcf3c92487ca	495
idinor	0:dcf3c92487ca	496	/* Parse any options in the SYN. */
idinor	0:dcf3c92487ca	497	tcp_parseopt(npcb);
idinor	0:dcf3c92487ca	498	#if TCP_CALCULATE_EFF_SEND_MSS
idinor	0:dcf3c92487ca	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
idinor	0:dcf3c92487ca	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
idinor	0:dcf3c92487ca	501
idinor	0:dcf3c92487ca	502	snmp_inc_tcppassiveopens();
idinor	0:dcf3c92487ca	503
idinor	0:dcf3c92487ca	504	/* Send a SYN\|ACK together with the MSS option. */
idinor	0:dcf3c92487ca	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
idinor	0:dcf3c92487ca	506	if (rc != ERR_OK) {
idinor	0:dcf3c92487ca	507	tcp_abandon(npcb, 0);
idinor	0:dcf3c92487ca	508	return rc;
idinor	0:dcf3c92487ca	509	}
idinor	0:dcf3c92487ca	510	return tcp_output(npcb);
idinor	0:dcf3c92487ca	511	}
idinor	0:dcf3c92487ca	512	return ERR_OK;
idinor	0:dcf3c92487ca	513	}
idinor	0:dcf3c92487ca	514
idinor	0:dcf3c92487ca	515	/**
idinor	0:dcf3c92487ca	516	* Called by tcp_input() when a segment arrives for a connection in
idinor	0:dcf3c92487ca	517	* TIME_WAIT.
idinor	0:dcf3c92487ca	518	*
idinor	0:dcf3c92487ca	519	* @param pcb the tcp_pcb for which a segment arrived
idinor	0:dcf3c92487ca	520	*
idinor	0:dcf3c92487ca	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
idinor	0:dcf3c92487ca	522	* involved is passed as a parameter to this function
idinor	0:dcf3c92487ca	523	*/
idinor	0:dcf3c92487ca	524	static err_t
idinor	0:dcf3c92487ca	525	tcp_timewait_input(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	526	{
idinor	0:dcf3c92487ca	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
idinor	0:dcf3c92487ca	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
idinor	0:dcf3c92487ca	529	* - first check sequence number - we skip that one in TIME_WAIT (always
idinor	0:dcf3c92487ca	530	* acceptable since we only send ACKs)
idinor	0:dcf3c92487ca	531	* - second check the RST bit (... return) */
idinor	0:dcf3c92487ca	532	if (flags & TCP_RST) {
idinor	0:dcf3c92487ca	533	return ERR_OK;
idinor	0:dcf3c92487ca	534	}
idinor	0:dcf3c92487ca	535	/* - fourth, check the SYN bit, */
idinor	0:dcf3c92487ca	536	if (flags & TCP_SYN) {
idinor	0:dcf3c92487ca	537	/* If an incoming segment is not acceptable, an acknowledgment
idinor	0:dcf3c92487ca	538	should be sent in reply */
idinor	0:dcf3c92487ca	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
idinor	0:dcf3c92487ca	540	/* If the SYN is in the window it is an error, send a reset */
idinor	0:dcf3c92487ca	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
idinor	0:dcf3c92487ca	542	tcphdr->dest, tcphdr->src);
idinor	0:dcf3c92487ca	543	return ERR_OK;
idinor	0:dcf3c92487ca	544	}
idinor	0:dcf3c92487ca	545	} else if (flags & TCP_FIN) {
idinor	0:dcf3c92487ca	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
idinor	0:dcf3c92487ca	547	Restart the 2 MSL time-wait timeout.*/
idinor	0:dcf3c92487ca	548	pcb->tmr = tcp_ticks;
idinor	0:dcf3c92487ca	549	}
idinor	0:dcf3c92487ca	550
idinor	0:dcf3c92487ca	551	if ((tcplen > 0)) {
idinor	0:dcf3c92487ca	552	/* Acknowledge data, FIN or out-of-window SYN */
idinor	0:dcf3c92487ca	553	pcb->flags \|= TF_ACK_NOW;
idinor	0:dcf3c92487ca	554	return tcp_output(pcb);
idinor	0:dcf3c92487ca	555	}
idinor	0:dcf3c92487ca	556	return ERR_OK;
idinor	0:dcf3c92487ca	557	}
idinor	0:dcf3c92487ca	558
idinor	0:dcf3c92487ca	559	/**
idinor	0:dcf3c92487ca	560	* Implements the TCP state machine. Called by tcp_input. In some
idinor	0:dcf3c92487ca	561	* states tcp_receive() is called to receive data. The tcp_seg
idinor	0:dcf3c92487ca	562	* argument will be freed by the caller (tcp_input()) unless the
idinor	0:dcf3c92487ca	563	* recv_data pointer in the pcb is set.
idinor	0:dcf3c92487ca	564	*
idinor	0:dcf3c92487ca	565	* @param pcb the tcp_pcb for which a segment arrived
idinor	0:dcf3c92487ca	566	*
idinor	0:dcf3c92487ca	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
idinor	0:dcf3c92487ca	568	* involved is passed as a parameter to this function
idinor	0:dcf3c92487ca	569	*/
idinor	0:dcf3c92487ca	570	static err_t
idinor	0:dcf3c92487ca	571	tcp_process(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	572	{
idinor	0:dcf3c92487ca	573	struct tcp_seg *rseg;
idinor	0:dcf3c92487ca	574	u8_t acceptable = 0;
idinor	0:dcf3c92487ca	575	err_t err;
idinor	0:dcf3c92487ca	576
idinor	0:dcf3c92487ca	577	err = ERR_OK;
idinor	0:dcf3c92487ca	578
idinor	0:dcf3c92487ca	579	/* Process incoming RST segments. */
idinor	0:dcf3c92487ca	580	if (flags & TCP_RST) {
idinor	0:dcf3c92487ca	581	/* First, determine if the reset is acceptable. */
idinor	0:dcf3c92487ca	582	if (pcb->state == SYN_SENT) {
idinor	0:dcf3c92487ca	583	if (ackno == pcb->snd_nxt) {
idinor	0:dcf3c92487ca	584	acceptable = 1;
idinor	0:dcf3c92487ca	585	}
idinor	0:dcf3c92487ca	586	} else {
idinor	0:dcf3c92487ca	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
idinor	0:dcf3c92487ca	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
idinor	0:dcf3c92487ca	589	acceptable = 1;
idinor	0:dcf3c92487ca	590	}
idinor	0:dcf3c92487ca	591	}
idinor	0:dcf3c92487ca	592
idinor	0:dcf3c92487ca	593	if (acceptable) {
idinor	0:dcf3c92487ca	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
idinor	0:dcf3c92487ca	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
idinor	0:dcf3c92487ca	596	recv_flags \|= TF_RESET;
idinor	0:dcf3c92487ca	597	pcb->flags &= ~TF_ACK_DELAY;
idinor	0:dcf3c92487ca	598	return ERR_RST;
idinor	0:dcf3c92487ca	599	} else {
idinor	0:dcf3c92487ca	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
idinor	0:dcf3c92487ca	601	seqno, pcb->rcv_nxt));
idinor	0:dcf3c92487ca	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
idinor	0:dcf3c92487ca	603	seqno, pcb->rcv_nxt));
idinor	0:dcf3c92487ca	604	return ERR_OK;
idinor	0:dcf3c92487ca	605	}
idinor	0:dcf3c92487ca	606	}
idinor	0:dcf3c92487ca	607
idinor	0:dcf3c92487ca	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
idinor	0:dcf3c92487ca	609	/* Cope with new connection attempt after remote end crashed */
idinor	0:dcf3c92487ca	610	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	611	return ERR_OK;
idinor	0:dcf3c92487ca	612	}
idinor	0:dcf3c92487ca	613
idinor	0:dcf3c92487ca	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
idinor	0:dcf3c92487ca	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
idinor	0:dcf3c92487ca	616	pcb->tmr = tcp_ticks;
idinor	0:dcf3c92487ca	617	}
idinor	0:dcf3c92487ca	618	pcb->keep_cnt_sent = 0;
idinor	0:dcf3c92487ca	619
idinor	0:dcf3c92487ca	620	tcp_parseopt(pcb);
idinor	0:dcf3c92487ca	621
idinor	0:dcf3c92487ca	622	/* Do different things depending on the TCP state. */
idinor	0:dcf3c92487ca	623	switch (pcb->state) {
idinor	0:dcf3c92487ca	624	case SYN_SENT:
idinor	0:dcf3c92487ca	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
idinor	0:dcf3c92487ca	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
idinor	0:dcf3c92487ca	627	/* received SYN ACK with expected sequence number? */
idinor	0:dcf3c92487ca	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
idinor	0:dcf3c92487ca	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
idinor	0:dcf3c92487ca	630	pcb->snd_buf++;
idinor	0:dcf3c92487ca	631	pcb->rcv_nxt = seqno + 1;
idinor	0:dcf3c92487ca	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
idinor	0:dcf3c92487ca	633	pcb->lastack = ackno;
idinor	0:dcf3c92487ca	634	pcb->snd_wnd = tcphdr->wnd;
idinor	0:dcf3c92487ca	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
idinor	0:dcf3c92487ca	636	pcb->state = ESTABLISHED;
idinor	0:dcf3c92487ca	637
idinor	0:dcf3c92487ca	638	#if TCP_CALCULATE_EFF_SEND_MSS
idinor	0:dcf3c92487ca	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
idinor	0:dcf3c92487ca	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
idinor	0:dcf3c92487ca	641
idinor	0:dcf3c92487ca	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
idinor	0:dcf3c92487ca	643	* but for the default value of pcb->mss) */
idinor	0:dcf3c92487ca	644	pcb->ssthresh = pcb->mss * 10;
idinor	0:dcf3c92487ca	645
idinor	0:dcf3c92487ca	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
idinor	0:dcf3c92487ca	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
idinor	0:dcf3c92487ca	648	--pcb->snd_queuelen;
idinor	0:dcf3c92487ca	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	650	rseg = pcb->unacked;
idinor	0:dcf3c92487ca	651	pcb->unacked = rseg->next;
idinor	0:dcf3c92487ca	652
idinor	0:dcf3c92487ca	653	/* If there's nothing left to acknowledge, stop the retransmit
idinor	0:dcf3c92487ca	654	timer, otherwise reset it to start again */
idinor	0:dcf3c92487ca	655	if(pcb->unacked == NULL)
idinor	0:dcf3c92487ca	656	pcb->rtime = -1;
idinor	0:dcf3c92487ca	657	else {
idinor	0:dcf3c92487ca	658	pcb->rtime = 0;
idinor	0:dcf3c92487ca	659	pcb->nrtx = 0;
idinor	0:dcf3c92487ca	660	}
idinor	0:dcf3c92487ca	661
idinor	0:dcf3c92487ca	662	tcp_seg_free(rseg);
idinor	0:dcf3c92487ca	663
idinor	0:dcf3c92487ca	664	/* Call the user specified function to call when sucessfully
idinor	0:dcf3c92487ca	665	* connected. */
idinor	0:dcf3c92487ca	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
idinor	0:dcf3c92487ca	667	if (err == ERR_ABRT) {
idinor	0:dcf3c92487ca	668	return ERR_ABRT;
idinor	0:dcf3c92487ca	669	}
idinor	0:dcf3c92487ca	670	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	671	}
idinor	0:dcf3c92487ca	672	/* received ACK? possibly a half-open connection */
idinor	0:dcf3c92487ca	673	else if (flags & TCP_ACK) {
idinor	0:dcf3c92487ca	674	/* send a RST to bring the other side in a non-synchronized state. */
idinor	0:dcf3c92487ca	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
idinor	0:dcf3c92487ca	676	tcphdr->dest, tcphdr->src);
idinor	0:dcf3c92487ca	677	}
idinor	0:dcf3c92487ca	678	break;
idinor	0:dcf3c92487ca	679	case SYN_RCVD:
idinor	0:dcf3c92487ca	680	if (flags & TCP_ACK) {
idinor	0:dcf3c92487ca	681	/* expected ACK number? */
idinor	0:dcf3c92487ca	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
idinor	0:dcf3c92487ca	683	u16_t old_cwnd;
idinor	0:dcf3c92487ca	684	pcb->state = ESTABLISHED;
idinor	0:dcf3c92487ca	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
idinor	0:dcf3c92487ca	686	#if LWIP_CALLBACK_API
idinor	0:dcf3c92487ca	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
idinor	0:dcf3c92487ca	688	#endif
idinor	0:dcf3c92487ca	689	/* Call the accept function. */
idinor	0:dcf3c92487ca	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
idinor	0:dcf3c92487ca	691	if (err != ERR_OK) {
idinor	0:dcf3c92487ca	692	/* If the accept function returns with an error, we abort
idinor	0:dcf3c92487ca	693	* the connection. */
idinor	0:dcf3c92487ca	694	/* Already aborted? */
idinor	0:dcf3c92487ca	695	if (err != ERR_ABRT) {
idinor	0:dcf3c92487ca	696	tcp_abort(pcb);
idinor	0:dcf3c92487ca	697	}
idinor	0:dcf3c92487ca	698	return ERR_ABRT;
idinor	0:dcf3c92487ca	699	}
idinor	0:dcf3c92487ca	700	old_cwnd = pcb->cwnd;
idinor	0:dcf3c92487ca	701	/* If there was any data contained within this ACK,
idinor	0:dcf3c92487ca	702	* we'd better pass it on to the application as well. */
idinor	0:dcf3c92487ca	703	tcp_receive(pcb);
idinor	0:dcf3c92487ca	704
idinor	0:dcf3c92487ca	705	/* Prevent ACK for SYN to generate a sent event */
idinor	0:dcf3c92487ca	706	if (pcb->acked != 0) {
idinor	0:dcf3c92487ca	707	pcb->acked--;
idinor	0:dcf3c92487ca	708	}
idinor	0:dcf3c92487ca	709
idinor	0:dcf3c92487ca	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
idinor	0:dcf3c92487ca	711
idinor	0:dcf3c92487ca	712	if (recv_flags & TF_GOT_FIN) {
idinor	0:dcf3c92487ca	713	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	714	pcb->state = CLOSE_WAIT;
idinor	0:dcf3c92487ca	715	}
idinor	0:dcf3c92487ca	716	} else {
idinor	0:dcf3c92487ca	717	/* incorrect ACK number, send RST */
idinor	0:dcf3c92487ca	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
idinor	0:dcf3c92487ca	719	tcphdr->dest, tcphdr->src);
idinor	0:dcf3c92487ca	720	}
idinor	0:dcf3c92487ca	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
idinor	0:dcf3c92487ca	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
idinor	0:dcf3c92487ca	723	tcp_rexmit(pcb);
idinor	0:dcf3c92487ca	724	}
idinor	0:dcf3c92487ca	725	break;
idinor	0:dcf3c92487ca	726	case CLOSE_WAIT:
idinor	0:dcf3c92487ca	727	/* FALLTHROUGH */
idinor	0:dcf3c92487ca	728	case ESTABLISHED:
idinor	0:dcf3c92487ca	729	tcp_receive(pcb);
idinor	0:dcf3c92487ca	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
idinor	0:dcf3c92487ca	731	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	732	pcb->state = CLOSE_WAIT;
idinor	0:dcf3c92487ca	733	}
idinor	0:dcf3c92487ca	734	break;
idinor	0:dcf3c92487ca	735	case FIN_WAIT_1:
idinor	0:dcf3c92487ca	736	tcp_receive(pcb);
idinor	0:dcf3c92487ca	737	if (recv_flags & TF_GOT_FIN) {
idinor	0:dcf3c92487ca	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
idinor	0:dcf3c92487ca	739	LWIP_DEBUGF(TCP_DEBUG,
idinor	0:dcf3c92487ca	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
idinor	0:dcf3c92487ca	741	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	742	tcp_pcb_purge(pcb);
idinor	0:dcf3c92487ca	743	TCP_RMV(&tcp_active_pcbs, pcb);
idinor	0:dcf3c92487ca	744	pcb->state = TIME_WAIT;
idinor	0:dcf3c92487ca	745	TCP_REG(&tcp_tw_pcbs, pcb);
idinor	0:dcf3c92487ca	746	} else {
idinor	0:dcf3c92487ca	747	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	748	pcb->state = CLOSING;
idinor	0:dcf3c92487ca	749	}
idinor	0:dcf3c92487ca	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
idinor	0:dcf3c92487ca	751	pcb->state = FIN_WAIT_2;
idinor	0:dcf3c92487ca	752	}
idinor	0:dcf3c92487ca	753	break;
idinor	0:dcf3c92487ca	754	case FIN_WAIT_2:
idinor	0:dcf3c92487ca	755	tcp_receive(pcb);
idinor	0:dcf3c92487ca	756	if (recv_flags & TF_GOT_FIN) {
idinor	0:dcf3c92487ca	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
idinor	0:dcf3c92487ca	758	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	759	tcp_pcb_purge(pcb);
idinor	0:dcf3c92487ca	760	TCP_RMV(&tcp_active_pcbs, pcb);
idinor	0:dcf3c92487ca	761	pcb->state = TIME_WAIT;
idinor	0:dcf3c92487ca	762	TCP_REG(&tcp_tw_pcbs, pcb);
idinor	0:dcf3c92487ca	763	}
idinor	0:dcf3c92487ca	764	break;
idinor	0:dcf3c92487ca	765	case CLOSING:
idinor	0:dcf3c92487ca	766	tcp_receive(pcb);
idinor	0:dcf3c92487ca	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
idinor	0:dcf3c92487ca	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
idinor	0:dcf3c92487ca	769	tcp_pcb_purge(pcb);
idinor	0:dcf3c92487ca	770	TCP_RMV(&tcp_active_pcbs, pcb);
idinor	0:dcf3c92487ca	771	pcb->state = TIME_WAIT;
idinor	0:dcf3c92487ca	772	TCP_REG(&tcp_tw_pcbs, pcb);
idinor	0:dcf3c92487ca	773	}
idinor	0:dcf3c92487ca	774	break;
idinor	0:dcf3c92487ca	775	case LAST_ACK:
idinor	0:dcf3c92487ca	776	tcp_receive(pcb);
idinor	0:dcf3c92487ca	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
idinor	0:dcf3c92487ca	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
idinor	0:dcf3c92487ca	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
idinor	0:dcf3c92487ca	780	recv_flags \|= TF_CLOSED;
idinor	0:dcf3c92487ca	781	}
idinor	0:dcf3c92487ca	782	break;
idinor	0:dcf3c92487ca	783	default:
idinor	0:dcf3c92487ca	784	break;
idinor	0:dcf3c92487ca	785	}
idinor	0:dcf3c92487ca	786	return ERR_OK;
idinor	0:dcf3c92487ca	787	}
idinor	0:dcf3c92487ca	788
idinor	0:dcf3c92487ca	789	#if TCP_QUEUE_OOSEQ
idinor	0:dcf3c92487ca	790	/**
idinor	0:dcf3c92487ca	791	* Insert segment into the list (segments covered with new one will be deleted)
idinor	0:dcf3c92487ca	792	*
idinor	0:dcf3c92487ca	793	* Called from tcp_receive()
idinor	0:dcf3c92487ca	794	*/
idinor	0:dcf3c92487ca	795	static void
idinor	0:dcf3c92487ca	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
idinor	0:dcf3c92487ca	797	{
idinor	0:dcf3c92487ca	798	struct tcp_seg *old_seg;
idinor	0:dcf3c92487ca	799
idinor	0:dcf3c92487ca	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	801	/* received segment overlaps all following segments */
idinor	0:dcf3c92487ca	802	tcp_segs_free(next);
idinor	0:dcf3c92487ca	803	next = NULL;
idinor	0:dcf3c92487ca	804	}
idinor	0:dcf3c92487ca	805	else {
idinor	0:dcf3c92487ca	806	/* delete some following segments
idinor	0:dcf3c92487ca	807	oos queue may have segments with FIN flag */
idinor	0:dcf3c92487ca	808	while (next &&
idinor	0:dcf3c92487ca	809	TCP_SEQ_GEQ((seqno + cseg->len),
idinor	0:dcf3c92487ca	810	(next->tcphdr->seqno + next->len))) {
idinor	0:dcf3c92487ca	811	/* cseg with FIN already processed */
idinor	0:dcf3c92487ca	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
idinor	0:dcf3c92487ca	814	}
idinor	0:dcf3c92487ca	815	old_seg = next;
idinor	0:dcf3c92487ca	816	next = next->next;
idinor	0:dcf3c92487ca	817	tcp_seg_free(old_seg);
idinor	0:dcf3c92487ca	818	}
idinor	0:dcf3c92487ca	819	if (next &&
idinor	0:dcf3c92487ca	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
idinor	0:dcf3c92487ca	821	/* We need to trim the incoming segment. */
idinor	0:dcf3c92487ca	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
idinor	0:dcf3c92487ca	823	pbuf_realloc(cseg->p, cseg->len);
idinor	0:dcf3c92487ca	824	}
idinor	0:dcf3c92487ca	825	}
idinor	0:dcf3c92487ca	826	cseg->next = next;
idinor	0:dcf3c92487ca	827	}
idinor	0:dcf3c92487ca	828	#endif /* TCP_QUEUE_OOSEQ */
idinor	0:dcf3c92487ca	829
idinor	0:dcf3c92487ca	830	/**
idinor	0:dcf3c92487ca	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
idinor	0:dcf3c92487ca	832	* data, and if so frees the memory of the buffered data. Next, is places the
idinor	0:dcf3c92487ca	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
idinor	0:dcf3c92487ca	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
idinor	0:dcf3c92487ca	835	* i it has been removed from the buffer.
idinor	0:dcf3c92487ca	836	*
idinor	0:dcf3c92487ca	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
idinor	0:dcf3c92487ca	838	* estimation, the RTT is estimated here as well.
idinor	0:dcf3c92487ca	839	*
idinor	0:dcf3c92487ca	840	* Called from tcp_process().
idinor	0:dcf3c92487ca	841	*/
idinor	0:dcf3c92487ca	842	static void
idinor	0:dcf3c92487ca	843	tcp_receive(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	844	{
idinor	0:dcf3c92487ca	845	struct tcp_seg *next;
idinor	0:dcf3c92487ca	846	#if TCP_QUEUE_OOSEQ
idinor	0:dcf3c92487ca	847	struct tcp_seg prev, cseg;
idinor	0:dcf3c92487ca	848	#endif /* TCP_QUEUE_OOSEQ */
idinor	0:dcf3c92487ca	849	struct pbuf *p;
idinor	0:dcf3c92487ca	850	s32_t off;
idinor	0:dcf3c92487ca	851	s16_t m;
idinor	0:dcf3c92487ca	852	u32_t right_wnd_edge;
idinor	0:dcf3c92487ca	853	u16_t new_tot_len;
idinor	0:dcf3c92487ca	854	int found_dupack = 0;
idinor	0:dcf3c92487ca	855
idinor	0:dcf3c92487ca	856	if (flags & TCP_ACK) {
idinor	0:dcf3c92487ca	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
idinor	0:dcf3c92487ca	858
idinor	0:dcf3c92487ca	859	/* Update window. */
idinor	0:dcf3c92487ca	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
idinor	0:dcf3c92487ca	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
idinor	0:dcf3c92487ca	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
idinor	0:dcf3c92487ca	863	pcb->snd_wnd = tcphdr->wnd;
idinor	0:dcf3c92487ca	864	pcb->snd_wl1 = seqno;
idinor	0:dcf3c92487ca	865	pcb->snd_wl2 = ackno;
idinor	0:dcf3c92487ca	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
idinor	0:dcf3c92487ca	867	pcb->persist_backoff = 0;
idinor	0:dcf3c92487ca	868	}
idinor	0:dcf3c92487ca	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
idinor	0:dcf3c92487ca	870	#if TCP_WND_DEBUG
idinor	0:dcf3c92487ca	871	} else {
idinor	0:dcf3c92487ca	872	if (pcb->snd_wnd != tcphdr->wnd) {
idinor	0:dcf3c92487ca	873	LWIP_DEBUGF(TCP_WND_DEBUG,
idinor	0:dcf3c92487ca	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
idinor	0:dcf3c92487ca	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
idinor	0:dcf3c92487ca	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
idinor	0:dcf3c92487ca	877	}
idinor	0:dcf3c92487ca	878	#endif /* TCP_WND_DEBUG */
idinor	0:dcf3c92487ca	879	}
idinor	0:dcf3c92487ca	880
idinor	0:dcf3c92487ca	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
idinor	0:dcf3c92487ca	882	* duplicate ack if:
idinor	0:dcf3c92487ca	883	* 1) It doesn't ACK new data
idinor	0:dcf3c92487ca	884	* 2) length of received packet is zero (i.e. no payload)
idinor	0:dcf3c92487ca	885	* 3) the advertised window hasn't changed
idinor	0:dcf3c92487ca	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
idinor	0:dcf3c92487ca	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
idinor	0:dcf3c92487ca	888	*
idinor	0:dcf3c92487ca	889	* If it passes all five, should process as a dupack:
idinor	0:dcf3c92487ca	890	* a) dupacks < 3: do nothing
idinor	0:dcf3c92487ca	891	* b) dupacks == 3: fast retransmit
idinor	0:dcf3c92487ca	892	* c) dupacks > 3: increase cwnd
idinor	0:dcf3c92487ca	893	*
idinor	0:dcf3c92487ca	894	* If it only passes 1-3, should reset dupack counter (and add to
idinor	0:dcf3c92487ca	895	* stats, which we don't do in lwIP)
idinor	0:dcf3c92487ca	896	*
idinor	0:dcf3c92487ca	897	* If it only passes 1, should reset dupack counter
idinor	0:dcf3c92487ca	898	*
idinor	0:dcf3c92487ca	899	*/
idinor	0:dcf3c92487ca	900
idinor	0:dcf3c92487ca	901	/* Clause 1 */
idinor	0:dcf3c92487ca	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
idinor	0:dcf3c92487ca	903	pcb->acked = 0;
idinor	0:dcf3c92487ca	904	/* Clause 2 */
idinor	0:dcf3c92487ca	905	if (tcplen == 0) {
idinor	0:dcf3c92487ca	906	/* Clause 3 */
idinor	0:dcf3c92487ca	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
idinor	0:dcf3c92487ca	908	/* Clause 4 */
idinor	0:dcf3c92487ca	909	if (pcb->rtime >= 0) {
idinor	0:dcf3c92487ca	910	/* Clause 5 */
idinor	0:dcf3c92487ca	911	if (pcb->lastack == ackno) {
idinor	0:dcf3c92487ca	912	found_dupack = 1;
idinor	0:dcf3c92487ca	913	if (pcb->dupacks + 1 > pcb->dupacks)
idinor	0:dcf3c92487ca	914	++pcb->dupacks;
idinor	0:dcf3c92487ca	915	if (pcb->dupacks > 3) {
idinor	0:dcf3c92487ca	916	/* Inflate the congestion window, but not if it means that
idinor	0:dcf3c92487ca	917	the value overflows. */
idinor	0:dcf3c92487ca	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
idinor	0:dcf3c92487ca	919	pcb->cwnd += pcb->mss;
idinor	0:dcf3c92487ca	920	}
idinor	0:dcf3c92487ca	921	} else if (pcb->dupacks == 3) {
idinor	0:dcf3c92487ca	922	/* Do fast retransmit */
idinor	0:dcf3c92487ca	923	tcp_rexmit_fast(pcb);
idinor	0:dcf3c92487ca	924	}
idinor	0:dcf3c92487ca	925	}
idinor	0:dcf3c92487ca	926	}
idinor	0:dcf3c92487ca	927	}
idinor	0:dcf3c92487ca	928	}
idinor	0:dcf3c92487ca	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
idinor	0:dcf3c92487ca	930	* count of consecutive duplicate acks */
idinor	0:dcf3c92487ca	931	if (!found_dupack) {
idinor	0:dcf3c92487ca	932	pcb->dupacks = 0;
idinor	0:dcf3c92487ca	933	}
idinor	0:dcf3c92487ca	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
idinor	0:dcf3c92487ca	935	/* We come here when the ACK acknowledges new data. */
idinor	0:dcf3c92487ca	936
idinor	0:dcf3c92487ca	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
idinor	0:dcf3c92487ca	938	in fast retransmit. Also reset the congestion window to the
idinor	0:dcf3c92487ca	939	slow start threshold. */
idinor	0:dcf3c92487ca	940	if (pcb->flags & TF_INFR) {
idinor	0:dcf3c92487ca	941	pcb->flags &= ~TF_INFR;
idinor	0:dcf3c92487ca	942	pcb->cwnd = pcb->ssthresh;
idinor	0:dcf3c92487ca	943	}
idinor	0:dcf3c92487ca	944
idinor	0:dcf3c92487ca	945	/* Reset the number of retransmissions. */
idinor	0:dcf3c92487ca	946	pcb->nrtx = 0;
idinor	0:dcf3c92487ca	947
idinor	0:dcf3c92487ca	948	/* Reset the retransmission time-out. */
idinor	0:dcf3c92487ca	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
idinor	0:dcf3c92487ca	950
idinor	0:dcf3c92487ca	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
idinor	0:dcf3c92487ca	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
idinor	0:dcf3c92487ca	953
idinor	0:dcf3c92487ca	954	pcb->snd_buf += pcb->acked;
idinor	0:dcf3c92487ca	955
idinor	0:dcf3c92487ca	956	/* Reset the fast retransmit variables. */
idinor	0:dcf3c92487ca	957	pcb->dupacks = 0;
idinor	0:dcf3c92487ca	958	pcb->lastack = ackno;
idinor	0:dcf3c92487ca	959
idinor	0:dcf3c92487ca	960	/* Update the congestion control variables (cwnd and
idinor	0:dcf3c92487ca	961	ssthresh). */
idinor	0:dcf3c92487ca	962	if (pcb->state >= ESTABLISHED) {
idinor	0:dcf3c92487ca	963	if (pcb->cwnd < pcb->ssthresh) {
idinor	0:dcf3c92487ca	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
idinor	0:dcf3c92487ca	965	pcb->cwnd += pcb->mss;
idinor	0:dcf3c92487ca	966	}
idinor	0:dcf3c92487ca	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
idinor	0:dcf3c92487ca	968	} else {
idinor	0:dcf3c92487ca	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
idinor	0:dcf3c92487ca	970	if (new_cwnd > pcb->cwnd) {
idinor	0:dcf3c92487ca	971	pcb->cwnd = new_cwnd;
idinor	0:dcf3c92487ca	972	}
idinor	0:dcf3c92487ca	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
idinor	0:dcf3c92487ca	974	}
idinor	0:dcf3c92487ca	975	}
idinor	0:dcf3c92487ca	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
idinor	0:dcf3c92487ca	977	ackno,
idinor	0:dcf3c92487ca	978	pcb->unacked != NULL?
idinor	0:dcf3c92487ca	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
idinor	0:dcf3c92487ca	980	pcb->unacked != NULL?
idinor	0:dcf3c92487ca	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
idinor	0:dcf3c92487ca	982
idinor	0:dcf3c92487ca	983	/* Remove segment from the unacknowledged list if the incoming
idinor	0:dcf3c92487ca	984	ACK acknowlegdes them. */
idinor	0:dcf3c92487ca	985	while (pcb->unacked != NULL &&
idinor	0:dcf3c92487ca	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
idinor	0:dcf3c92487ca	987	TCP_TCPLEN(pcb->unacked), ackno)) {
idinor	0:dcf3c92487ca	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
idinor	0:dcf3c92487ca	989	ntohl(pcb->unacked->tcphdr->seqno),
idinor	0:dcf3c92487ca	990	ntohl(pcb->unacked->tcphdr->seqno) +
idinor	0:dcf3c92487ca	991	TCP_TCPLEN(pcb->unacked)));
idinor	0:dcf3c92487ca	992
idinor	0:dcf3c92487ca	993	next = pcb->unacked;
idinor	0:dcf3c92487ca	994	pcb->unacked = pcb->unacked->next;
idinor	0:dcf3c92487ca	995
idinor	0:dcf3c92487ca	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
idinor	0:dcf3c92487ca	998	/* Prevent ACK for FIN to generate a sent event */
idinor	0:dcf3c92487ca	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
idinor	0:dcf3c92487ca	1000	pcb->acked--;
idinor	0:dcf3c92487ca	1001	}
idinor	0:dcf3c92487ca	1002
idinor	0:dcf3c92487ca	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
idinor	0:dcf3c92487ca	1004	tcp_seg_free(next);
idinor	0:dcf3c92487ca	1005
idinor	0:dcf3c92487ca	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	1007	if (pcb->snd_queuelen != 0) {
idinor	0:dcf3c92487ca	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
idinor	0:dcf3c92487ca	1009	pcb->unsent != NULL);
idinor	0:dcf3c92487ca	1010	}
idinor	0:dcf3c92487ca	1011	}
idinor	0:dcf3c92487ca	1012
idinor	0:dcf3c92487ca	1013	/* If there's nothing left to acknowledge, stop the retransmit
idinor	0:dcf3c92487ca	1014	timer, otherwise reset it to start again */
idinor	0:dcf3c92487ca	1015	if(pcb->unacked == NULL)
idinor	0:dcf3c92487ca	1016	pcb->rtime = -1;
idinor	0:dcf3c92487ca	1017	else
idinor	0:dcf3c92487ca	1018	pcb->rtime = 0;
idinor	0:dcf3c92487ca	1019
idinor	0:dcf3c92487ca	1020	pcb->polltmr = 0;
idinor	0:dcf3c92487ca	1021	} else {
idinor	0:dcf3c92487ca	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
idinor	0:dcf3c92487ca	1023	pcb->acked = 0;
idinor	0:dcf3c92487ca	1024	}
idinor	0:dcf3c92487ca	1025
idinor	0:dcf3c92487ca	1026	/* We go through the ->unsent list to see if any of the segments
idinor	0:dcf3c92487ca	1027	on the list are acknowledged by the ACK. This may seem
idinor	0:dcf3c92487ca	1028	strange since an "unsent" segment shouldn't be acked. The
idinor	0:dcf3c92487ca	1029	rationale is that lwIP puts all outstanding segments on the
idinor	0:dcf3c92487ca	1030	->unsent list after a retransmission, so these segments may
idinor	0:dcf3c92487ca	1031	in fact have been sent once. */
idinor	0:dcf3c92487ca	1032	while (pcb->unsent != NULL &&
idinor	0:dcf3c92487ca	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
idinor	0:dcf3c92487ca	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
idinor	0:dcf3c92487ca	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
idinor	0:dcf3c92487ca	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
idinor	0:dcf3c92487ca	1037	TCP_TCPLEN(pcb->unsent)));
idinor	0:dcf3c92487ca	1038
idinor	0:dcf3c92487ca	1039	next = pcb->unsent;
idinor	0:dcf3c92487ca	1040	pcb->unsent = pcb->unsent->next;
idinor	0:dcf3c92487ca	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
idinor	0:dcf3c92487ca	1043	/* Prevent ACK for FIN to generate a sent event */
idinor	0:dcf3c92487ca	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
idinor	0:dcf3c92487ca	1045	pcb->acked--;
idinor	0:dcf3c92487ca	1046	}
idinor	0:dcf3c92487ca	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
idinor	0:dcf3c92487ca	1048	tcp_seg_free(next);
idinor	0:dcf3c92487ca	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
idinor	0:dcf3c92487ca	1050	if (pcb->snd_queuelen != 0) {
idinor	0:dcf3c92487ca	1051	LWIP_ASSERT("tcp_receive: valid queue length",
idinor	0:dcf3c92487ca	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
idinor	0:dcf3c92487ca	1053	}
idinor	0:dcf3c92487ca	1054	}
idinor	0:dcf3c92487ca	1055	/* End of ACK for new data processing. */
idinor	0:dcf3c92487ca	1056
idinor	0:dcf3c92487ca	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
idinor	0:dcf3c92487ca	1058	pcb->rttest, pcb->rtseq, ackno));
idinor	0:dcf3c92487ca	1059
idinor	0:dcf3c92487ca	1060	/* RTT estimation calculations. This is done by checking if the
idinor	0:dcf3c92487ca	1061	incoming segment acknowledges the segment we use to take a
idinor	0:dcf3c92487ca	1062	round-trip time measurement. */
idinor	0:dcf3c92487ca	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
idinor	0:dcf3c92487ca	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
idinor	0:dcf3c92487ca	1065	and a round-trip shouldn't be that long... */
idinor	0:dcf3c92487ca	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
idinor	0:dcf3c92487ca	1067
idinor	0:dcf3c92487ca	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
idinor	0:dcf3c92487ca	1069	m, m * TCP_SLOW_INTERVAL));
idinor	0:dcf3c92487ca	1070
idinor	0:dcf3c92487ca	1071	/* This is taken directly from VJs original code in his paper */
idinor	0:dcf3c92487ca	1072	m = m - (pcb->sa >> 3);
idinor	0:dcf3c92487ca	1073	pcb->sa += m;
idinor	0:dcf3c92487ca	1074	if (m < 0) {
idinor	0:dcf3c92487ca	1075	m = -m;
idinor	0:dcf3c92487ca	1076	}
idinor	0:dcf3c92487ca	1077	m = m - (pcb->sv >> 2);
idinor	0:dcf3c92487ca	1078	pcb->sv += m;
idinor	0:dcf3c92487ca	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
idinor	0:dcf3c92487ca	1080
idinor	0:dcf3c92487ca	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
idinor	0:dcf3c92487ca	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
idinor	0:dcf3c92487ca	1083
idinor	0:dcf3c92487ca	1084	pcb->rttest = 0;
idinor	0:dcf3c92487ca	1085	}
idinor	0:dcf3c92487ca	1086	}
idinor	0:dcf3c92487ca	1087
idinor	0:dcf3c92487ca	1088	/* If the incoming segment contains data, we must process it
idinor	0:dcf3c92487ca	1089	further. */
idinor	0:dcf3c92487ca	1090	if (tcplen > 0) {
idinor	0:dcf3c92487ca	1091	/* This code basically does three things:
idinor	0:dcf3c92487ca	1092
idinor	0:dcf3c92487ca	1093	+) If the incoming segment contains data that is the next
idinor	0:dcf3c92487ca	1094	in-sequence data, this data is passed to the application. This
idinor	0:dcf3c92487ca	1095	might involve trimming the first edge of the data. The rcv_nxt
idinor	0:dcf3c92487ca	1096	variable and the advertised window are adjusted.
idinor	0:dcf3c92487ca	1097
idinor	0:dcf3c92487ca	1098	+) If the incoming segment has data that is above the next
idinor	0:dcf3c92487ca	1099	sequence number expected (->rcv_nxt), the segment is placed on
idinor	0:dcf3c92487ca	1100	the ->ooseq queue. This is done by finding the appropriate
idinor	0:dcf3c92487ca	1101	place in the ->ooseq queue (which is ordered by sequence
idinor	0:dcf3c92487ca	1102	number) and trim the segment in both ends if needed. An
idinor	0:dcf3c92487ca	1103	immediate ACK is sent to indicate that we received an
idinor	0:dcf3c92487ca	1104	out-of-sequence segment.
idinor	0:dcf3c92487ca	1105
idinor	0:dcf3c92487ca	1106	+) Finally, we check if the first segment on the ->ooseq queue
idinor	0:dcf3c92487ca	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
idinor	0:dcf3c92487ca	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
idinor	0:dcf3c92487ca	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
idinor	0:dcf3c92487ca	1110	segments that are now on sequence are chained onto the
idinor	0:dcf3c92487ca	1111	incoming segment so that we only need to call the application
idinor	0:dcf3c92487ca	1112	once.
idinor	0:dcf3c92487ca	1113	*/
idinor	0:dcf3c92487ca	1114
idinor	0:dcf3c92487ca	1115	/* First, we check if we must trim the first edge. We have to do
idinor	0:dcf3c92487ca	1116	this if the sequence number of the incoming segment is less
idinor	0:dcf3c92487ca	1117	than rcv_nxt, and the sequence number plus the length of the
idinor	0:dcf3c92487ca	1118	segment is larger than rcv_nxt. */
idinor	0:dcf3c92487ca	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
idinor	0:dcf3c92487ca	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
idinor	0:dcf3c92487ca	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
idinor	0:dcf3c92487ca	1122	/* Trimming the first edge is done by pushing the payload
idinor	0:dcf3c92487ca	1123	pointer in the pbuf downwards. This is somewhat tricky since
idinor	0:dcf3c92487ca	1124	we do not want to discard the full contents of the pbuf up to
idinor	0:dcf3c92487ca	1125	the new starting point of the data since we have to keep the
idinor	0:dcf3c92487ca	1126	TCP header which is present in the first pbuf in the chain.
idinor	0:dcf3c92487ca	1127
idinor	0:dcf3c92487ca	1128	What is done is really quite a nasty hack: the first pbuf in
idinor	0:dcf3c92487ca	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
idinor	0:dcf3c92487ca	1130	able to deallocate the whole pbuf, we cannot change this
idinor	0:dcf3c92487ca	1131	inseg.p pointer to point to any of the later pbufs in the
idinor	0:dcf3c92487ca	1132	chain. Instead, we point the ->payload pointer in the first
idinor	0:dcf3c92487ca	1133	pbuf to data in one of the later pbufs. We also set the
idinor	0:dcf3c92487ca	1134	inseg.data pointer to point to the right place. This way, the
idinor	0:dcf3c92487ca	1135	->p pointer will still point to the first pbuf, but the
idinor	0:dcf3c92487ca	1136	->p->payload pointer will point to data in another pbuf.
idinor	0:dcf3c92487ca	1137
idinor	0:dcf3c92487ca	1138	After we are done with adjusting the pbuf pointers we must
idinor	0:dcf3c92487ca	1139	adjust the ->data pointer in the seg and the segment
idinor	0:dcf3c92487ca	1140	length.*/
idinor	0:dcf3c92487ca	1141
idinor	0:dcf3c92487ca	1142	off = pcb->rcv_nxt - seqno;
idinor	0:dcf3c92487ca	1143	p = inseg.p;
idinor	0:dcf3c92487ca	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
idinor	0:dcf3c92487ca	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
idinor	0:dcf3c92487ca	1146	if (inseg.p->len < off) {
idinor	0:dcf3c92487ca	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
idinor	0:dcf3c92487ca	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
idinor	0:dcf3c92487ca	1149	while (p->len < off) {
idinor	0:dcf3c92487ca	1150	off -= p->len;
idinor	0:dcf3c92487ca	1151	/* KJM following line changed (with addition of new_tot_len var)
idinor	0:dcf3c92487ca	1152	to fix bug #9076
idinor	0:dcf3c92487ca	1153	inseg.p->tot_len -= p->len; */
idinor	0:dcf3c92487ca	1154	p->tot_len = new_tot_len;
idinor	0:dcf3c92487ca	1155	p->len = 0;
idinor	0:dcf3c92487ca	1156	p = p->next;
idinor	0:dcf3c92487ca	1157	}
idinor	0:dcf3c92487ca	1158	if(pbuf_header(p, (s16_t)-off)) {
idinor	0:dcf3c92487ca	1159	/* Do we need to cope with this failing? Assert for now */
idinor	0:dcf3c92487ca	1160	LWIP_ASSERT("pbuf_header failed", 0);
idinor	0:dcf3c92487ca	1161	}
idinor	0:dcf3c92487ca	1162	} else {
idinor	0:dcf3c92487ca	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
idinor	0:dcf3c92487ca	1164	/* Do we need to cope with this failing? Assert for now */
idinor	0:dcf3c92487ca	1165	LWIP_ASSERT("pbuf_header failed", 0);
idinor	0:dcf3c92487ca	1166	}
idinor	0:dcf3c92487ca	1167	}
idinor	0:dcf3c92487ca	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
idinor	0:dcf3c92487ca	1169	to fix bug #9076 */
idinor	0:dcf3c92487ca	1170	inseg.dataptr = p->payload;
idinor	0:dcf3c92487ca	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
idinor	0:dcf3c92487ca	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
idinor	0:dcf3c92487ca	1173	}
idinor	0:dcf3c92487ca	1174	else {
idinor	0:dcf3c92487ca	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
idinor	0:dcf3c92487ca	1176	/* the whole segment is < rcv_nxt */
idinor	0:dcf3c92487ca	1177	/* must be a duplicate of a packet that has already been correctly handled */
idinor	0:dcf3c92487ca	1178
idinor	0:dcf3c92487ca	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
idinor	0:dcf3c92487ca	1180	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	1181	}
idinor	0:dcf3c92487ca	1182	}
idinor	0:dcf3c92487ca	1183
idinor	0:dcf3c92487ca	1184	/* The sequence number must be within the window (above rcv_nxt
idinor	0:dcf3c92487ca	1185	and below rcv_nxt + rcv_wnd) in order to be further
idinor	0:dcf3c92487ca	1186	processed. */
idinor	0:dcf3c92487ca	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
idinor	0:dcf3c92487ca	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
idinor	0:dcf3c92487ca	1189	if (pcb->rcv_nxt == seqno) {
idinor	0:dcf3c92487ca	1190	/* The incoming segment is the next in sequence. We check if
idinor	0:dcf3c92487ca	1191	we have to trim the end of the segment and update rcv_nxt
idinor	0:dcf3c92487ca	1192	and pass the data to the application. */
idinor	0:dcf3c92487ca	1193	tcplen = TCP_TCPLEN(&inseg);
idinor	0:dcf3c92487ca	1194
idinor	0:dcf3c92487ca	1195	if (tcplen > pcb->rcv_wnd) {
idinor	0:dcf3c92487ca	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
idinor	0:dcf3c92487ca	1197	("tcp_receive: other end overran receive window"
idinor	0:dcf3c92487ca	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
idinor	0:dcf3c92487ca	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
idinor	0:dcf3c92487ca	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	1201	/* Must remove the FIN from the header as we're trimming
idinor	0:dcf3c92487ca	1202	* that byte of sequence-space from the packet */
idinor	0:dcf3c92487ca	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
idinor	0:dcf3c92487ca	1204	}
idinor	0:dcf3c92487ca	1205	/* Adjust length of segment to fit in the window. */
idinor	0:dcf3c92487ca	1206	inseg.len = pcb->rcv_wnd;
idinor	0:dcf3c92487ca	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
idinor	0:dcf3c92487ca	1208	inseg.len -= 1;
idinor	0:dcf3c92487ca	1209	}
idinor	0:dcf3c92487ca	1210	pbuf_realloc(inseg.p, inseg.len);
idinor	0:dcf3c92487ca	1211	tcplen = TCP_TCPLEN(&inseg);
idinor	0:dcf3c92487ca	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
idinor	0:dcf3c92487ca	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
idinor	0:dcf3c92487ca	1214	}
idinor	0:dcf3c92487ca	1215	#if TCP_QUEUE_OOSEQ
idinor	0:dcf3c92487ca	1216	/* Received in-sequence data, adjust ooseq data if:
idinor	0:dcf3c92487ca	1217	- FIN has been received or
idinor	0:dcf3c92487ca	1218	- inseq overlaps with ooseq */
idinor	0:dcf3c92487ca	1219	if (pcb->ooseq != NULL) {
idinor	0:dcf3c92487ca	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
idinor	0:dcf3c92487ca	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
idinor	0:dcf3c92487ca	1223	/* Received in-order FIN means anything that was received
idinor	0:dcf3c92487ca	1224	* out of order must now have been received in-order, so
idinor	0:dcf3c92487ca	1225	* bin the ooseq queue */
idinor	0:dcf3c92487ca	1226	while (pcb->ooseq != NULL) {
idinor	0:dcf3c92487ca	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
idinor	0:dcf3c92487ca	1228	pcb->ooseq = pcb->ooseq->next;
idinor	0:dcf3c92487ca	1229	tcp_seg_free(old_ooseq);
idinor	0:dcf3c92487ca	1230	}
idinor	0:dcf3c92487ca	1231	}
idinor	0:dcf3c92487ca	1232	else {
idinor	0:dcf3c92487ca	1233	next = pcb->ooseq;
idinor	0:dcf3c92487ca	1234	/* Remove all segments on ooseq that are covered by inseg already.
idinor	0:dcf3c92487ca	1235	* FIN is copied from ooseq to inseg if present. */
idinor	0:dcf3c92487ca	1236	while (next &&
idinor	0:dcf3c92487ca	1237	TCP_SEQ_GEQ(seqno + tcplen,
idinor	0:dcf3c92487ca	1238	next->tcphdr->seqno + next->len)) {
idinor	0:dcf3c92487ca	1239	/* inseg cannot have FIN here (already processed above) */
idinor	0:dcf3c92487ca	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
idinor	0:dcf3c92487ca	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
idinor	0:dcf3c92487ca	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
idinor	0:dcf3c92487ca	1243	tcplen = TCP_TCPLEN(&inseg);
idinor	0:dcf3c92487ca	1244	}
idinor	0:dcf3c92487ca	1245	prev = next;
idinor	0:dcf3c92487ca	1246	next = next->next;
idinor	0:dcf3c92487ca	1247	tcp_seg_free(prev);
idinor	0:dcf3c92487ca	1248	}
idinor	0:dcf3c92487ca	1249	/* Now trim right side of inseg if it overlaps with the first
idinor	0:dcf3c92487ca	1250	* segment on ooseq */
idinor	0:dcf3c92487ca	1251	if (next &&
idinor	0:dcf3c92487ca	1252	TCP_SEQ_GT(seqno + tcplen,
idinor	0:dcf3c92487ca	1253	next->tcphdr->seqno)) {
idinor	0:dcf3c92487ca	1254	/* inseg cannot have FIN here (already processed above) */
idinor	0:dcf3c92487ca	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
idinor	0:dcf3c92487ca	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
idinor	0:dcf3c92487ca	1257	inseg.len -= 1;
idinor	0:dcf3c92487ca	1258	}
idinor	0:dcf3c92487ca	1259	pbuf_realloc(inseg.p, inseg.len);
idinor	0:dcf3c92487ca	1260	tcplen = TCP_TCPLEN(&inseg);
idinor	0:dcf3c92487ca	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
idinor	0:dcf3c92487ca	1262	(seqno + tcplen) == next->tcphdr->seqno);
idinor	0:dcf3c92487ca	1263	}
idinor	0:dcf3c92487ca	1264	pcb->ooseq = next;
idinor	0:dcf3c92487ca	1265	}
idinor	0:dcf3c92487ca	1266	}
idinor	0:dcf3c92487ca	1267	#endif /* TCP_QUEUE_OOSEQ */
idinor	0:dcf3c92487ca	1268
idinor	0:dcf3c92487ca	1269	pcb->rcv_nxt = seqno + tcplen;
idinor	0:dcf3c92487ca	1270
idinor	0:dcf3c92487ca	1271	/* Update the receiver's (our) window. */
idinor	0:dcf3c92487ca	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
idinor	0:dcf3c92487ca	1273	pcb->rcv_wnd -= tcplen;
idinor	0:dcf3c92487ca	1274
idinor	0:dcf3c92487ca	1275	tcp_update_rcv_ann_wnd(pcb);
idinor	0:dcf3c92487ca	1276
idinor	0:dcf3c92487ca	1277	/* If there is data in the segment, we make preparations to
idinor	0:dcf3c92487ca	1278	pass this up to the application. The ->recv_data variable
idinor	0:dcf3c92487ca	1279	is used for holding the pbuf that goes to the
idinor	0:dcf3c92487ca	1280	application. The code for reassembling out-of-sequence data
idinor	0:dcf3c92487ca	1281	chains its data on this pbuf as well.
idinor	0:dcf3c92487ca	1282
idinor	0:dcf3c92487ca	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
idinor	0:dcf3c92487ca	1284	be used to indicate to the application that the remote side has
idinor	0:dcf3c92487ca	1285	closed its end of the connection. */
idinor	0:dcf3c92487ca	1286	if (inseg.p->tot_len > 0) {
idinor	0:dcf3c92487ca	1287	recv_data = inseg.p;
idinor	0:dcf3c92487ca	1288	/* Since this pbuf now is the responsibility of the
idinor	0:dcf3c92487ca	1289	application, we delete our reference to it so that we won't
idinor	0:dcf3c92487ca	1290	(mistakingly) deallocate it. */
idinor	0:dcf3c92487ca	1291	inseg.p = NULL;
idinor	0:dcf3c92487ca	1292	}
idinor	0:dcf3c92487ca	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
idinor	0:dcf3c92487ca	1295	recv_flags \|= TF_GOT_FIN;
idinor	0:dcf3c92487ca	1296	}
idinor	0:dcf3c92487ca	1297
idinor	0:dcf3c92487ca	1298	#if TCP_QUEUE_OOSEQ
idinor	0:dcf3c92487ca	1299	/* We now check if we have segments on the ->ooseq queue that
idinor	0:dcf3c92487ca	1300	are now in sequence. */
idinor	0:dcf3c92487ca	1301	while (pcb->ooseq != NULL &&
idinor	0:dcf3c92487ca	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
idinor	0:dcf3c92487ca	1303
idinor	0:dcf3c92487ca	1304	cseg = pcb->ooseq;
idinor	0:dcf3c92487ca	1305	seqno = pcb->ooseq->tcphdr->seqno;
idinor	0:dcf3c92487ca	1306
idinor	0:dcf3c92487ca	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
idinor	0:dcf3c92487ca	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
idinor	0:dcf3c92487ca	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
idinor	0:dcf3c92487ca	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
idinor	0:dcf3c92487ca	1311
idinor	0:dcf3c92487ca	1312	tcp_update_rcv_ann_wnd(pcb);
idinor	0:dcf3c92487ca	1313
idinor	0:dcf3c92487ca	1314	if (cseg->p->tot_len > 0) {
idinor	0:dcf3c92487ca	1315	/* Chain this pbuf onto the pbuf that we will pass to
idinor	0:dcf3c92487ca	1316	the application. */
idinor	0:dcf3c92487ca	1317	if (recv_data) {
idinor	0:dcf3c92487ca	1318	pbuf_cat(recv_data, cseg->p);
idinor	0:dcf3c92487ca	1319	} else {
idinor	0:dcf3c92487ca	1320	recv_data = cseg->p;
idinor	0:dcf3c92487ca	1321	}
idinor	0:dcf3c92487ca	1322	cseg->p = NULL;
idinor	0:dcf3c92487ca	1323	}
idinor	0:dcf3c92487ca	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
idinor	0:dcf3c92487ca	1326	recv_flags \|= TF_GOT_FIN;
idinor	0:dcf3c92487ca	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
idinor	0:dcf3c92487ca	1328	pcb->state = CLOSE_WAIT;
idinor	0:dcf3c92487ca	1329	}
idinor	0:dcf3c92487ca	1330	}
idinor	0:dcf3c92487ca	1331
idinor	0:dcf3c92487ca	1332	pcb->ooseq = cseg->next;
idinor	0:dcf3c92487ca	1333	tcp_seg_free(cseg);
idinor	0:dcf3c92487ca	1334	}
idinor	0:dcf3c92487ca	1335	#endif /* TCP_QUEUE_OOSEQ */
idinor	0:dcf3c92487ca	1336
idinor	0:dcf3c92487ca	1337
idinor	0:dcf3c92487ca	1338	/* Acknowledge the segment(s). */
idinor	0:dcf3c92487ca	1339	tcp_ack(pcb);
idinor	0:dcf3c92487ca	1340
idinor	0:dcf3c92487ca	1341	} else {
idinor	0:dcf3c92487ca	1342	/* We get here if the incoming segment is out-of-sequence. */
idinor	0:dcf3c92487ca	1343	tcp_send_empty_ack(pcb);
idinor	0:dcf3c92487ca	1344	#if TCP_QUEUE_OOSEQ
idinor	0:dcf3c92487ca	1345	/* We queue the segment on the ->ooseq queue. */
idinor	0:dcf3c92487ca	1346	if (pcb->ooseq == NULL) {
idinor	0:dcf3c92487ca	1347	pcb->ooseq = tcp_seg_copy(&inseg);
idinor	0:dcf3c92487ca	1348	} else {
idinor	0:dcf3c92487ca	1349	/* If the queue is not empty, we walk through the queue and
idinor	0:dcf3c92487ca	1350	try to find a place where the sequence number of the
idinor	0:dcf3c92487ca	1351	incoming segment is between the sequence numbers of the
idinor	0:dcf3c92487ca	1352	previous and the next segment on the ->ooseq queue. That is
idinor	0:dcf3c92487ca	1353	the place where we put the incoming segment. If needed, we
idinor	0:dcf3c92487ca	1354	trim the second edges of the previous and the incoming
idinor	0:dcf3c92487ca	1355	segment so that it will fit into the sequence.
idinor	0:dcf3c92487ca	1356
idinor	0:dcf3c92487ca	1357	If the incoming segment has the same sequence number as a
idinor	0:dcf3c92487ca	1358	segment on the ->ooseq queue, we discard the segment that
idinor	0:dcf3c92487ca	1359	contains less data. */
idinor	0:dcf3c92487ca	1360
idinor	0:dcf3c92487ca	1361	prev = NULL;
idinor	0:dcf3c92487ca	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
idinor	0:dcf3c92487ca	1363	if (seqno == next->tcphdr->seqno) {
idinor	0:dcf3c92487ca	1364	/* The sequence number of the incoming segment is the
idinor	0:dcf3c92487ca	1365	same as the sequence number of the segment on
idinor	0:dcf3c92487ca	1366	->ooseq. We check the lengths to see which one to
idinor	0:dcf3c92487ca	1367	discard. */
idinor	0:dcf3c92487ca	1368	if (inseg.len > next->len) {
idinor	0:dcf3c92487ca	1369	/* The incoming segment is larger than the old
idinor	0:dcf3c92487ca	1370	segment. We replace some segments with the new
idinor	0:dcf3c92487ca	1371	one. */
idinor	0:dcf3c92487ca	1372	cseg = tcp_seg_copy(&inseg);
idinor	0:dcf3c92487ca	1373	if (cseg != NULL) {
idinor	0:dcf3c92487ca	1374	if (prev != NULL) {
idinor	0:dcf3c92487ca	1375	prev->next = cseg;
idinor	0:dcf3c92487ca	1376	} else {
idinor	0:dcf3c92487ca	1377	pcb->ooseq = cseg;
idinor	0:dcf3c92487ca	1378	}
idinor	0:dcf3c92487ca	1379	tcp_oos_insert_segment(cseg, next);
idinor	0:dcf3c92487ca	1380	}
idinor	0:dcf3c92487ca	1381	break;
idinor	0:dcf3c92487ca	1382	} else {
idinor	0:dcf3c92487ca	1383	/* Either the lenghts are the same or the incoming
idinor	0:dcf3c92487ca	1384	segment was smaller than the old one; in either
idinor	0:dcf3c92487ca	1385	case, we ditch the incoming segment. */
idinor	0:dcf3c92487ca	1386	break;
idinor	0:dcf3c92487ca	1387	}
idinor	0:dcf3c92487ca	1388	} else {
idinor	0:dcf3c92487ca	1389	if (prev == NULL) {
idinor	0:dcf3c92487ca	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
idinor	0:dcf3c92487ca	1391	/* The sequence number of the incoming segment is lower
idinor	0:dcf3c92487ca	1392	than the sequence number of the first segment on the
idinor	0:dcf3c92487ca	1393	queue. We put the incoming segment first on the
idinor	0:dcf3c92487ca	1394	queue. */
idinor	0:dcf3c92487ca	1395	cseg = tcp_seg_copy(&inseg);
idinor	0:dcf3c92487ca	1396	if (cseg != NULL) {
idinor	0:dcf3c92487ca	1397	pcb->ooseq = cseg;
idinor	0:dcf3c92487ca	1398	tcp_oos_insert_segment(cseg, next);
idinor	0:dcf3c92487ca	1399	}
idinor	0:dcf3c92487ca	1400	break;
idinor	0:dcf3c92487ca	1401	}
idinor	0:dcf3c92487ca	1402	} else {
idinor	0:dcf3c92487ca	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
idinor	0:dcf3c92487ca	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
idinor	0:dcf3c92487ca	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
idinor	0:dcf3c92487ca	1406	/* The sequence number of the incoming segment is in
idinor	0:dcf3c92487ca	1407	between the sequence numbers of the previous and
idinor	0:dcf3c92487ca	1408	the next segment on ->ooseq. We trim trim the previous
idinor	0:dcf3c92487ca	1409	segment, delete next segments that included in received segment
idinor	0:dcf3c92487ca	1410	and trim received, if needed. */
idinor	0:dcf3c92487ca	1411	cseg = tcp_seg_copy(&inseg);
idinor	0:dcf3c92487ca	1412	if (cseg != NULL) {
idinor	0:dcf3c92487ca	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
idinor	0:dcf3c92487ca	1414	/* We need to trim the prev segment. */
idinor	0:dcf3c92487ca	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
idinor	0:dcf3c92487ca	1416	pbuf_realloc(prev->p, prev->len);
idinor	0:dcf3c92487ca	1417	}
idinor	0:dcf3c92487ca	1418	prev->next = cseg;
idinor	0:dcf3c92487ca	1419	tcp_oos_insert_segment(cseg, next);
idinor	0:dcf3c92487ca	1420	}
idinor	0:dcf3c92487ca	1421	break;
idinor	0:dcf3c92487ca	1422	}
idinor	0:dcf3c92487ca	1423	}
idinor	0:dcf3c92487ca	1424	/* If the "next" segment is the last segment on the
idinor	0:dcf3c92487ca	1425	ooseq queue, we add the incoming segment to the end
idinor	0:dcf3c92487ca	1426	of the list. */
idinor	0:dcf3c92487ca	1427	if (next->next == NULL &&
idinor	0:dcf3c92487ca	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
idinor	0:dcf3c92487ca	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	1430	/* segment "next" already contains all data */
idinor	0:dcf3c92487ca	1431	break;
idinor	0:dcf3c92487ca	1432	}
idinor	0:dcf3c92487ca	1433	next->next = tcp_seg_copy(&inseg);
idinor	0:dcf3c92487ca	1434	if (next->next != NULL) {
idinor	0:dcf3c92487ca	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
idinor	0:dcf3c92487ca	1436	/* We need to trim the last segment. */
idinor	0:dcf3c92487ca	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
idinor	0:dcf3c92487ca	1438	pbuf_realloc(next->p, next->len);
idinor	0:dcf3c92487ca	1439	}
idinor	0:dcf3c92487ca	1440	/* check if the remote side overruns our receive window */
idinor	0:dcf3c92487ca	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
idinor	0:dcf3c92487ca	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
idinor	0:dcf3c92487ca	1443	("tcp_receive: other end overran receive window"
idinor	0:dcf3c92487ca	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
idinor	0:dcf3c92487ca	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
idinor	0:dcf3c92487ca	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
idinor	0:dcf3c92487ca	1447	/* Must remove the FIN from the header as we're trimming
idinor	0:dcf3c92487ca	1448	* that byte of sequence-space from the packet */
idinor	0:dcf3c92487ca	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
idinor	0:dcf3c92487ca	1450	}
idinor	0:dcf3c92487ca	1451	/* Adjust length of segment to fit in the window. */
idinor	0:dcf3c92487ca	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
idinor	0:dcf3c92487ca	1453	pbuf_realloc(next->next->p, next->next->len);
idinor	0:dcf3c92487ca	1454	tcplen = TCP_TCPLEN(next->next);
idinor	0:dcf3c92487ca	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
idinor	0:dcf3c92487ca	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
idinor	0:dcf3c92487ca	1457	}
idinor	0:dcf3c92487ca	1458	}
idinor	0:dcf3c92487ca	1459	break;
idinor	0:dcf3c92487ca	1460	}
idinor	0:dcf3c92487ca	1461	}
idinor	0:dcf3c92487ca	1462	prev = next;
idinor	0:dcf3c92487ca	1463	}
idinor	0:dcf3c92487ca	1464	}
idinor	0:dcf3c92487ca	1465	#endif /* TCP_QUEUE_OOSEQ */
idinor	0:dcf3c92487ca	1466
idinor	0:dcf3c92487ca	1467	}
idinor	0:dcf3c92487ca	1468	} else {
idinor	0:dcf3c92487ca	1469	/* The incoming segment is not withing the window. */
idinor	0:dcf3c92487ca	1470	tcp_send_empty_ack(pcb);
idinor	0:dcf3c92487ca	1471	}
idinor	0:dcf3c92487ca	1472	} else {
idinor	0:dcf3c92487ca	1473	/* Segments with length 0 is taken care of here. Segments that
idinor	0:dcf3c92487ca	1474	fall out of the window are ACKed. */
idinor	0:dcf3c92487ca	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
idinor	0:dcf3c92487ca	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
idinor	0:dcf3c92487ca	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
idinor	0:dcf3c92487ca	1478	tcp_ack_now(pcb);
idinor	0:dcf3c92487ca	1479	}
idinor	0:dcf3c92487ca	1480	}
idinor	0:dcf3c92487ca	1481	}
idinor	0:dcf3c92487ca	1482
idinor	0:dcf3c92487ca	1483	/**
idinor	0:dcf3c92487ca	1484	* Parses the options contained in the incoming segment.
idinor	0:dcf3c92487ca	1485	*
idinor	0:dcf3c92487ca	1486	* Called from tcp_listen_input() and tcp_process().
idinor	0:dcf3c92487ca	1487	* Currently, only the MSS option is supported!
idinor	0:dcf3c92487ca	1488	*
idinor	0:dcf3c92487ca	1489	* @param pcb the tcp_pcb for which a segment arrived
idinor	0:dcf3c92487ca	1490	*/
idinor	0:dcf3c92487ca	1491	static void
idinor	0:dcf3c92487ca	1492	tcp_parseopt(struct tcp_pcb *pcb)
idinor	0:dcf3c92487ca	1493	{
idinor	0:dcf3c92487ca	1494	u16_t c, max_c;
idinor	0:dcf3c92487ca	1495	u16_t mss;
idinor	0:dcf3c92487ca	1496	u8_t *opts, opt;
idinor	0:dcf3c92487ca	1497	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	1498	u32_t tsval;
idinor	0:dcf3c92487ca	1499	#endif
idinor	0:dcf3c92487ca	1500
idinor	0:dcf3c92487ca	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
idinor	0:dcf3c92487ca	1502
idinor	0:dcf3c92487ca	1503	/* Parse the TCP MSS option, if present. */
idinor	0:dcf3c92487ca	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
idinor	0:dcf3c92487ca	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
idinor	0:dcf3c92487ca	1506	for (c = 0; c < max_c; ) {
idinor	0:dcf3c92487ca	1507	opt = opts[c];
idinor	0:dcf3c92487ca	1508	switch (opt) {
idinor	0:dcf3c92487ca	1509	case 0x00:
idinor	0:dcf3c92487ca	1510	/* End of options. */
idinor	0:dcf3c92487ca	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
idinor	0:dcf3c92487ca	1512	return;
idinor	0:dcf3c92487ca	1513	case 0x01:
idinor	0:dcf3c92487ca	1514	/* NOP option. */
idinor	0:dcf3c92487ca	1515	++c;
idinor	0:dcf3c92487ca	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
idinor	0:dcf3c92487ca	1517	break;
idinor	0:dcf3c92487ca	1518	case 0x02:
idinor	0:dcf3c92487ca	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
idinor	0:dcf3c92487ca	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
idinor	0:dcf3c92487ca	1521	/* Bad length */
idinor	0:dcf3c92487ca	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
idinor	0:dcf3c92487ca	1523	return;
idinor	0:dcf3c92487ca	1524	}
idinor	0:dcf3c92487ca	1525	/* An MSS option with the right option length. */
idinor	0:dcf3c92487ca	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
idinor	0:dcf3c92487ca	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
idinor	0:dcf3c92487ca	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
idinor	0:dcf3c92487ca	1529	/* Advance to next option */
idinor	0:dcf3c92487ca	1530	c += 0x04;
idinor	0:dcf3c92487ca	1531	break;
idinor	0:dcf3c92487ca	1532	#if LWIP_TCP_TIMESTAMPS
idinor	0:dcf3c92487ca	1533	case 0x08:
idinor	0:dcf3c92487ca	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
idinor	0:dcf3c92487ca	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
idinor	0:dcf3c92487ca	1536	/* Bad length */
idinor	0:dcf3c92487ca	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
idinor	0:dcf3c92487ca	1538	return;
idinor	0:dcf3c92487ca	1539	}
idinor	0:dcf3c92487ca	1540	/* TCP timestamp option with valid length */
idinor	0:dcf3c92487ca	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
idinor	0:dcf3c92487ca	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
idinor	0:dcf3c92487ca	1543	if (flags & TCP_SYN) {
idinor	0:dcf3c92487ca	1544	pcb->ts_recent = ntohl(tsval);
idinor	0:dcf3c92487ca	1545	pcb->flags \|= TF_TIMESTAMP;
idinor	0:dcf3c92487ca	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
idinor	0:dcf3c92487ca	1547	pcb->ts_recent = ntohl(tsval);
idinor	0:dcf3c92487ca	1548	}
idinor	0:dcf3c92487ca	1549	/* Advance to next option */
idinor	0:dcf3c92487ca	1550	c += 0x0A;
idinor	0:dcf3c92487ca	1551	break;
idinor	0:dcf3c92487ca	1552	#endif
idinor	0:dcf3c92487ca	1553	default:
idinor	0:dcf3c92487ca	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
idinor	0:dcf3c92487ca	1555	if (opts[c + 1] == 0) {
idinor	0:dcf3c92487ca	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
idinor	0:dcf3c92487ca	1557	/* If the length field is zero, the options are malformed
idinor	0:dcf3c92487ca	1558	and we don't process them further. */
idinor	0:dcf3c92487ca	1559	return;
idinor	0:dcf3c92487ca	1560	}
idinor	0:dcf3c92487ca	1561	/* All other options have a length field, so that we easily
idinor	0:dcf3c92487ca	1562	can skip past them. */
idinor	0:dcf3c92487ca	1563	c += opts[c + 1];
idinor	0:dcf3c92487ca	1564	}
idinor	0:dcf3c92487ca	1565	}
idinor	0:dcf3c92487ca	1566	}
idinor	0:dcf3c92487ca	1567	}
idinor	0:dcf3c92487ca	1568
idinor	0:dcf3c92487ca	1569	#endif /* LWIP_TCP */

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Type:	Library
Created:	20 Jul 2011
Imports:	35
Forks:	0
Commits:	1
Dependents:	1
Dependencies:	0
Followers:	1

lwip/core/tcp_in.c@0:dcf3c92487ca, 2011-07-20 (annotated)

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