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lwip/core/tcp_in.c@11:da4498f591ee, 2010-08-05 (annotated)

Committer:: donatien
Date:: Thu Aug 05 15:01:33 2010 +0000
Revision:: 11:da4498f591ee
Parent:: 5:dd63a1e02b1b

Who changed what in which revision?

User	Revision	Line number	New contents of line
donatien	0:632c9925f013	1	/**
donatien	0:632c9925f013	2	* @file
donatien	0:632c9925f013	3	* Transmission Control Protocol, incoming traffic
donatien	0:632c9925f013	4	*
donatien	0:632c9925f013	5	* The input processing functions of the TCP layer.
donatien	0:632c9925f013	6	*
donatien	0:632c9925f013	7	* These functions are generally called in the order (ip_input() ->)
donatien	0:632c9925f013	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
donatien	0:632c9925f013	9	*
donatien	0:632c9925f013	10	*/
donatien	0:632c9925f013	11
donatien	0:632c9925f013	12	/*
donatien	0:632c9925f013	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
donatien	0:632c9925f013	14	* All rights reserved.
donatien	0:632c9925f013	15	*
donatien	0:632c9925f013	16	* Redistribution and use in source and binary forms, with or without modification,
donatien	0:632c9925f013	17	* are permitted provided that the following conditions are met:
donatien	0:632c9925f013	18	*
donatien	0:632c9925f013	19	* 1. Redistributions of source code must retain the above copyright notice,
donatien	0:632c9925f013	20	* this list of conditions and the following disclaimer.
donatien	0:632c9925f013	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
donatien	0:632c9925f013	22	* this list of conditions and the following disclaimer in the documentation
donatien	0:632c9925f013	23	* and/or other materials provided with the distribution.
donatien	0:632c9925f013	24	* 3. The name of the author may not be used to endorse or promote products
donatien	0:632c9925f013	25	* derived from this software without specific prior written permission.
donatien	0:632c9925f013	26	*
donatien	0:632c9925f013	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
donatien	0:632c9925f013	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
donatien	0:632c9925f013	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
donatien	0:632c9925f013	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
donatien	0:632c9925f013	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
donatien	0:632c9925f013	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
donatien	0:632c9925f013	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
donatien	0:632c9925f013	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
donatien	0:632c9925f013	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
donatien	0:632c9925f013	36	* OF SUCH DAMAGE.
donatien	0:632c9925f013	37	*
donatien	0:632c9925f013	38	* This file is part of the lwIP TCP/IP stack.
donatien	0:632c9925f013	39	*
donatien	0:632c9925f013	40	* Author: Adam Dunkels <adam@sics.se>
donatien	0:632c9925f013	41	*
donatien	0:632c9925f013	42	*/
donatien	0:632c9925f013	43
donatien	0:632c9925f013	44	#include "lwip/opt.h"
donatien	0:632c9925f013	45
donatien	0:632c9925f013	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
donatien	0:632c9925f013	47
donatien	0:632c9925f013	48	#include "lwip/tcp_impl.h"
donatien	0:632c9925f013	49	#include "lwip/def.h"
donatien	0:632c9925f013	50	#include "lwip/ip_addr.h"
donatien	0:632c9925f013	51	#include "lwip/netif.h"
donatien	0:632c9925f013	52	#include "lwip/mem.h"
donatien	0:632c9925f013	53	#include "lwip/memp.h"
donatien	0:632c9925f013	54	#include "lwip/inet_chksum.h"
donatien	0:632c9925f013	55	#include "lwip/stats.h"
donatien	0:632c9925f013	56	#include "lwip/snmp.h"
donatien	0:632c9925f013	57	#include "arch/perf.h"
donatien	0:632c9925f013	58
donatien	0:632c9925f013	59	/* These variables are global to all functions involved in the input
donatien	0:632c9925f013	60	processing of TCP segments. They are set by the tcp_input()
donatien	0:632c9925f013	61	function. */
donatien	0:632c9925f013	62	static struct tcp_seg inseg;
donatien	0:632c9925f013	63	static struct tcp_hdr *tcphdr;
donatien	0:632c9925f013	64	static struct ip_hdr *iphdr;
donatien	0:632c9925f013	65	static u32_t seqno, ackno;
donatien	0:632c9925f013	66	static u8_t flags;
donatien	0:632c9925f013	67	static u16_t tcplen;
donatien	0:632c9925f013	68
donatien	0:632c9925f013	69	static u8_t recv_flags;
donatien	0:632c9925f013	70	static struct pbuf *recv_data;
donatien	0:632c9925f013	71
donatien	0:632c9925f013	72	struct tcp_pcb *tcp_input_pcb;
donatien	0:632c9925f013	73
donatien	0:632c9925f013	74	/* Forward declarations. */
donatien	0:632c9925f013	75	static err_t tcp_process(struct tcp_pcb *pcb);
donatien	0:632c9925f013	76	static void tcp_receive(struct tcp_pcb *pcb);
donatien	0:632c9925f013	77	static void tcp_parseopt(struct tcp_pcb *pcb);
donatien	0:632c9925f013	78
donatien	0:632c9925f013	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
donatien	0:632c9925f013	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
donatien	0:632c9925f013	81
donatien	0:632c9925f013	82	/**
donatien	0:632c9925f013	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
donatien	0:632c9925f013	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
donatien	0:632c9925f013	85	* the TCP finite state machine. This function is called by the IP layer (in
donatien	0:632c9925f013	86	* ip_input()).
donatien	0:632c9925f013	87	*
donatien	0:632c9925f013	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
donatien	0:632c9925f013	89	* @param inp network interface on which this segment was received
donatien	0:632c9925f013	90	*/
donatien	0:632c9925f013	91	void
donatien	0:632c9925f013	92	tcp_input(struct pbuf p, struct netif inp)
donatien	0:632c9925f013	93	{
donatien	0:632c9925f013	94	struct tcp_pcb pcb, prev;
donatien	0:632c9925f013	95	struct tcp_pcb_listen *lpcb;
donatien	5:dd63a1e02b1b	96	#if SO_REUSE
donatien	5:dd63a1e02b1b	97	struct tcp_pcb *lpcb_prev = NULL;
donatien	5:dd63a1e02b1b	98	struct tcp_pcb_listen *lpcb_any = NULL;
donatien	5:dd63a1e02b1b	99	#endif /* SO_REUSE */
donatien	0:632c9925f013	100	u8_t hdrlen;
donatien	0:632c9925f013	101	err_t err;
donatien	0:632c9925f013	102
donatien	0:632c9925f013	103	PERF_START;
donatien	0:632c9925f013	104
donatien	0:632c9925f013	105	TCP_STATS_INC(tcp.recv);
donatien	0:632c9925f013	106	snmp_inc_tcpinsegs();
donatien	0:632c9925f013	107
donatien	0:632c9925f013	108	iphdr = (struct ip_hdr *)p->payload;
donatien	0:632c9925f013	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
donatien	0:632c9925f013	110
donatien	0:632c9925f013	111	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	112	tcp_debug_print(tcphdr);
donatien	0:632c9925f013	113	#endif
donatien	0:632c9925f013	114
donatien	0:632c9925f013	115	/* remove header from payload */
donatien	0:632c9925f013	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
donatien	0:632c9925f013	117	/* drop short packets */
donatien	0:632c9925f013	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
donatien	0:632c9925f013	119	TCP_STATS_INC(tcp.lenerr);
donatien	0:632c9925f013	120	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	121	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	122	pbuf_free(p);
donatien	0:632c9925f013	123	return;
donatien	0:632c9925f013	124	}
donatien	0:632c9925f013	125
donatien	0:632c9925f013	126	/* Don't even process incoming broadcasts/multicasts. */
donatien	5:dd63a1e02b1b	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
donatien	5:dd63a1e02b1b	128	ip_addr_ismulticast(&current_iphdr_dest)) {
donatien	0:632c9925f013	129	TCP_STATS_INC(tcp.proterr);
donatien	0:632c9925f013	130	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	131	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	132	pbuf_free(p);
donatien	0:632c9925f013	133	return;
donatien	0:632c9925f013	134	}
donatien	0:632c9925f013	135
donatien	0:632c9925f013	136	#if CHECKSUM_CHECK_TCP
donatien	0:632c9925f013	137	/* Verify TCP checksum. */
donatien	5:dd63a1e02b1b	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
donatien	0:632c9925f013	139	IP_PROTO_TCP, p->tot_len) != 0) {
donatien	0:632c9925f013	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
donatien	5:dd63a1e02b1b	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
donatien	0:632c9925f013	142	IP_PROTO_TCP, p->tot_len)));
donatien	0:632c9925f013	143	#if TCP_DEBUG
donatien	0:632c9925f013	144	tcp_debug_print(tcphdr);
donatien	0:632c9925f013	145	#endif /* TCP_DEBUG */
donatien	0:632c9925f013	146	TCP_STATS_INC(tcp.chkerr);
donatien	0:632c9925f013	147	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	148	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	149	pbuf_free(p);
donatien	0:632c9925f013	150	return;
donatien	0:632c9925f013	151	}
donatien	0:632c9925f013	152	#endif
donatien	0:632c9925f013	153
donatien	0:632c9925f013	154	/* Move the payload pointer in the pbuf so that it points to the
donatien	0:632c9925f013	155	TCP data instead of the TCP header. */
donatien	0:632c9925f013	156	hdrlen = TCPH_HDRLEN(tcphdr);
donatien	0:632c9925f013	157	if(pbuf_header(p, -(hdrlen * 4))){
donatien	0:632c9925f013	158	/* drop short packets */
donatien	0:632c9925f013	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
donatien	0:632c9925f013	160	TCP_STATS_INC(tcp.lenerr);
donatien	0:632c9925f013	161	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	162	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	163	pbuf_free(p);
donatien	0:632c9925f013	164	return;
donatien	0:632c9925f013	165	}
donatien	0:632c9925f013	166
donatien	0:632c9925f013	167	/* Convert fields in TCP header to host byte order. */
donatien	0:632c9925f013	168	tcphdr->src = ntohs(tcphdr->src);
donatien	0:632c9925f013	169	tcphdr->dest = ntohs(tcphdr->dest);
donatien	0:632c9925f013	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
donatien	0:632c9925f013	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
donatien	0:632c9925f013	172	tcphdr->wnd = ntohs(tcphdr->wnd);
donatien	0:632c9925f013	173
donatien	0:632c9925f013	174	flags = TCPH_FLAGS(tcphdr);
donatien	0:632c9925f013	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
donatien	0:632c9925f013	176
donatien	0:632c9925f013	177	/* Demultiplex an incoming segment. First, we check if it is destined
donatien	0:632c9925f013	178	for an active connection. */
donatien	0:632c9925f013	179	prev = NULL;
donatien	0:632c9925f013	180
donatien	0:632c9925f013	181
donatien	0:632c9925f013	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
donatien	0:632c9925f013	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
donatien	0:632c9925f013	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
donatien	0:632c9925f013	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
donatien	0:632c9925f013	186	if (pcb->remote_port == tcphdr->src &&
donatien	0:632c9925f013	187	pcb->local_port == tcphdr->dest &&
donatien	5:dd63a1e02b1b	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
donatien	5:dd63a1e02b1b	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
donatien	0:632c9925f013	190
donatien	0:632c9925f013	191	/* Move this PCB to the front of the list so that subsequent
donatien	0:632c9925f013	192	lookups will be faster (we exploit locality in TCP segment
donatien	0:632c9925f013	193	arrivals). */
donatien	0:632c9925f013	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
donatien	0:632c9925f013	195	if (prev != NULL) {
donatien	0:632c9925f013	196	prev->next = pcb->next;
donatien	0:632c9925f013	197	pcb->next = tcp_active_pcbs;
donatien	0:632c9925f013	198	tcp_active_pcbs = pcb;
donatien	0:632c9925f013	199	}
donatien	0:632c9925f013	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
donatien	0:632c9925f013	201	break;
donatien	0:632c9925f013	202	}
donatien	0:632c9925f013	203	prev = pcb;
donatien	0:632c9925f013	204	}
donatien	0:632c9925f013	205
donatien	0:632c9925f013	206	if (pcb == NULL) {
donatien	0:632c9925f013	207	/* If it did not go to an active connection, we check the connections
donatien	0:632c9925f013	208	in the TIME-WAIT state. */
donatien	0:632c9925f013	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
donatien	0:632c9925f013	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
donatien	0:632c9925f013	211	if (pcb->remote_port == tcphdr->src &&
donatien	0:632c9925f013	212	pcb->local_port == tcphdr->dest &&
donatien	5:dd63a1e02b1b	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
donatien	5:dd63a1e02b1b	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
donatien	0:632c9925f013	215	/* We don't really care enough to move this PCB to the front
donatien	0:632c9925f013	216	of the list since we are not very likely to receive that
donatien	0:632c9925f013	217	many segments for connections in TIME-WAIT. */
donatien	0:632c9925f013	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
donatien	0:632c9925f013	219	tcp_timewait_input(pcb);
donatien	0:632c9925f013	220	pbuf_free(p);
donatien	0:632c9925f013	221	return;
donatien	0:632c9925f013	222	}
donatien	0:632c9925f013	223	}
donatien	0:632c9925f013	224
donatien	5:dd63a1e02b1b	225	/* Finally, if we still did not get a match, we check all PCBs that
donatien	5:dd63a1e02b1b	226	are LISTENing for incoming connections. */
donatien	0:632c9925f013	227	prev = NULL;
donatien	0:632c9925f013	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
donatien	5:dd63a1e02b1b	229	if (lpcb->local_port == tcphdr->dest) {
donatien	5:dd63a1e02b1b	230	#if SO_REUSE
donatien	5:dd63a1e02b1b	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
donatien	5:dd63a1e02b1b	232	/* found an exact match */
donatien	5:dd63a1e02b1b	233	break;
donatien	5:dd63a1e02b1b	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
donatien	5:dd63a1e02b1b	235	/* found an ANY-match */
donatien	5:dd63a1e02b1b	236	lpcb_any = lpcb;
donatien	5:dd63a1e02b1b	237	lpcb_prev = prev;
donatien	0:632c9925f013	238	}
donatien	5:dd63a1e02b1b	239	#else /* SO_REUSE */
donatien	5:dd63a1e02b1b	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
donatien	5:dd63a1e02b1b	241	ip_addr_isany(&(lpcb->local_ip))) {
donatien	5:dd63a1e02b1b	242	/* found a match */
donatien	5:dd63a1e02b1b	243	break;
donatien	5:dd63a1e02b1b	244	}
donatien	5:dd63a1e02b1b	245	#endif /* SO_REUSE */
donatien	0:632c9925f013	246	}
donatien	0:632c9925f013	247	prev = (struct tcp_pcb *)lpcb;
donatien	0:632c9925f013	248	}
donatien	5:dd63a1e02b1b	249	#if SO_REUSE
donatien	5:dd63a1e02b1b	250	/* first try specific local IP */
donatien	5:dd63a1e02b1b	251	if (lpcb == NULL) {
donatien	5:dd63a1e02b1b	252	/* only pass to ANY if no specific local IP has been found */
donatien	5:dd63a1e02b1b	253	lpcb = lpcb_any;
donatien	5:dd63a1e02b1b	254	prev = lpcb_prev;
donatien	5:dd63a1e02b1b	255	}
donatien	5:dd63a1e02b1b	256	#endif /* SO_REUSE */
donatien	5:dd63a1e02b1b	257	if (lpcb != NULL) {
donatien	5:dd63a1e02b1b	258	/* Move this PCB to the front of the list so that subsequent
donatien	5:dd63a1e02b1b	259	lookups will be faster (we exploit locality in TCP segment
donatien	5:dd63a1e02b1b	260	arrivals). */
donatien	5:dd63a1e02b1b	261	if (prev != NULL) {
donatien	5:dd63a1e02b1b	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
donatien	5:dd63a1e02b1b	263	/* our successor is the remainder of the listening list */
donatien	5:dd63a1e02b1b	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
donatien	5:dd63a1e02b1b	265	/* put this listening pcb at the head of the listening list */
donatien	5:dd63a1e02b1b	266	tcp_listen_pcbs.listen_pcbs = lpcb;
donatien	5:dd63a1e02b1b	267	}
donatien	5:dd63a1e02b1b	268
donatien	5:dd63a1e02b1b	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
donatien	5:dd63a1e02b1b	270	tcp_listen_input(lpcb);
donatien	5:dd63a1e02b1b	271	pbuf_free(p);
donatien	5:dd63a1e02b1b	272	return;
donatien	5:dd63a1e02b1b	273	}
donatien	0:632c9925f013	274	}
donatien	0:632c9925f013	275
donatien	0:632c9925f013	276	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
donatien	0:632c9925f013	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
donatien	0:632c9925f013	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
donatien	0:632c9925f013	280	#endif /* TCP_INPUT_DEBUG */
donatien	0:632c9925f013	281
donatien	0:632c9925f013	282
donatien	0:632c9925f013	283	if (pcb != NULL) {
donatien	0:632c9925f013	284	/* The incoming segment belongs to a connection. */
donatien	0:632c9925f013	285	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	286	#if TCP_DEBUG
donatien	0:632c9925f013	287	tcp_debug_print_state(pcb->state);
donatien	0:632c9925f013	288	#endif /* TCP_DEBUG */
donatien	0:632c9925f013	289	#endif /* TCP_INPUT_DEBUG */
donatien	0:632c9925f013	290
donatien	0:632c9925f013	291	/* Set up a tcp_seg structure. */
donatien	0:632c9925f013	292	inseg.next = NULL;
donatien	0:632c9925f013	293	inseg.len = p->tot_len;
donatien	0:632c9925f013	294	inseg.dataptr = p->payload;
donatien	0:632c9925f013	295	inseg.p = p;
donatien	0:632c9925f013	296	inseg.tcphdr = tcphdr;
donatien	0:632c9925f013	297
donatien	0:632c9925f013	298	recv_data = NULL;
donatien	0:632c9925f013	299	recv_flags = 0;
donatien	0:632c9925f013	300
donatien	0:632c9925f013	301	/* If there is data which was previously "refused" by upper layer */
donatien	0:632c9925f013	302	if (pcb->refused_data != NULL) {
donatien	0:632c9925f013	303	/* Notify again application with data previously received. */
donatien	0:632c9925f013	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
donatien	0:632c9925f013	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
donatien	0:632c9925f013	306	if (err == ERR_OK) {
donatien	0:632c9925f013	307	pcb->refused_data = NULL;
donatien	0:632c9925f013	308	} else {
donatien	0:632c9925f013	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
donatien	0:632c9925f013	310	/* drop incoming packets, because pcb is "full" */
donatien	0:632c9925f013	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
donatien	0:632c9925f013	312	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	313	snmp_inc_tcpinerrs();
donatien	0:632c9925f013	314	pbuf_free(p);
donatien	0:632c9925f013	315	return;
donatien	0:632c9925f013	316	}
donatien	0:632c9925f013	317	}
donatien	0:632c9925f013	318	tcp_input_pcb = pcb;
donatien	0:632c9925f013	319	err = tcp_process(pcb);
donatien	0:632c9925f013	320	/* A return value of ERR_ABRT means that tcp_abort() was called
donatien	0:632c9925f013	321	and that the pcb has been freed. If so, we don't do anything. */
donatien	0:632c9925f013	322	if (err != ERR_ABRT) {
donatien	0:632c9925f013	323	if (recv_flags & TF_RESET) {
donatien	0:632c9925f013	324	/* TF_RESET means that the connection was reset by the other
donatien	0:632c9925f013	325	end. We then call the error callback to inform the
donatien	0:632c9925f013	326	application that the connection is dead before we
donatien	0:632c9925f013	327	deallocate the PCB. */
donatien	0:632c9925f013	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
donatien	0:632c9925f013	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	330	memp_free(MEMP_TCP_PCB, pcb);
donatien	0:632c9925f013	331	} else if (recv_flags & TF_CLOSED) {
donatien	0:632c9925f013	332	/* The connection has been closed and we will deallocate the
donatien	0:632c9925f013	333	PCB. */
donatien	0:632c9925f013	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	335	memp_free(MEMP_TCP_PCB, pcb);
donatien	0:632c9925f013	336	} else {
donatien	0:632c9925f013	337	err = ERR_OK;
donatien	0:632c9925f013	338	/* If the application has registered a "sent" function to be
donatien	0:632c9925f013	339	called when new send buffer space is available, we call it
donatien	0:632c9925f013	340	now. */
donatien	0:632c9925f013	341	if (pcb->acked > 0) {
donatien	0:632c9925f013	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
donatien	0:632c9925f013	343	if (err == ERR_ABRT) {
donatien	0:632c9925f013	344	goto aborted;
donatien	0:632c9925f013	345	}
donatien	0:632c9925f013	346	}
donatien	0:632c9925f013	347
donatien	0:632c9925f013	348	if (recv_data != NULL) {
donatien	5:dd63a1e02b1b	349	if (pcb->flags & TF_RXCLOSED) {
donatien	5:dd63a1e02b1b	350	/* received data although already closed -> abort (send RST) to
donatien	5:dd63a1e02b1b	351	notify the remote host that not all data has been processed */
donatien	5:dd63a1e02b1b	352	pbuf_free(recv_data);
donatien	5:dd63a1e02b1b	353	tcp_abort(pcb);
donatien	5:dd63a1e02b1b	354	goto aborted;
donatien	5:dd63a1e02b1b	355	}
donatien	5:dd63a1e02b1b	356	if (flags & TCP_PSH) {
donatien	0:632c9925f013	357	recv_data->flags \|= PBUF_FLAG_PUSH;
donatien	0:632c9925f013	358	}
donatien	0:632c9925f013	359
donatien	0:632c9925f013	360	/* Notify application that data has been received. */
donatien	0:632c9925f013	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
donatien	0:632c9925f013	362	if (err == ERR_ABRT) {
donatien	0:632c9925f013	363	goto aborted;
donatien	0:632c9925f013	364	}
donatien	0:632c9925f013	365
donatien	0:632c9925f013	366	/* If the upper layer can't receive this data, store it */
donatien	0:632c9925f013	367	if (err != ERR_OK) {
donatien	0:632c9925f013	368	pcb->refused_data = recv_data;
donatien	0:632c9925f013	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
donatien	0:632c9925f013	370	}
donatien	0:632c9925f013	371	}
donatien	0:632c9925f013	372
donatien	0:632c9925f013	373	/* If a FIN segment was received, we call the callback
donatien	0:632c9925f013	374	function with a NULL buffer to indicate EOF. */
donatien	0:632c9925f013	375	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	376	/* correct rcv_wnd as the application won't call tcp_recved()
donatien	0:632c9925f013	377	for the FIN's seqno */
donatien	0:632c9925f013	378	if (pcb->rcv_wnd != TCP_WND) {
donatien	0:632c9925f013	379	pcb->rcv_wnd++;
donatien	0:632c9925f013	380	}
donatien	5:dd63a1e02b1b	381	TCP_EVENT_CLOSED(pcb, err);
donatien	0:632c9925f013	382	if (err == ERR_ABRT) {
donatien	0:632c9925f013	383	goto aborted;
donatien	0:632c9925f013	384	}
donatien	0:632c9925f013	385	}
donatien	0:632c9925f013	386
donatien	0:632c9925f013	387	tcp_input_pcb = NULL;
donatien	0:632c9925f013	388	/* Try to send something out. */
donatien	0:632c9925f013	389	tcp_output(pcb);
donatien	0:632c9925f013	390	#if TCP_INPUT_DEBUG
donatien	0:632c9925f013	391	#if TCP_DEBUG
donatien	0:632c9925f013	392	tcp_debug_print_state(pcb->state);
donatien	0:632c9925f013	393	#endif /* TCP_DEBUG */
donatien	0:632c9925f013	394	#endif /* TCP_INPUT_DEBUG */
donatien	0:632c9925f013	395	}
donatien	0:632c9925f013	396	}
donatien	0:632c9925f013	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
donatien	0:632c9925f013	398	Below this line, 'pcb' may not be dereferenced! */
donatien	0:632c9925f013	399	aborted:
donatien	0:632c9925f013	400	tcp_input_pcb = NULL;
donatien	5:dd63a1e02b1b	401	recv_data = NULL;
donatien	0:632c9925f013	402
donatien	0:632c9925f013	403	/* give up our reference to inseg.p */
donatien	0:632c9925f013	404	if (inseg.p != NULL)
donatien	0:632c9925f013	405	{
donatien	0:632c9925f013	406	pbuf_free(inseg.p);
donatien	0:632c9925f013	407	inseg.p = NULL;
donatien	0:632c9925f013	408	}
donatien	0:632c9925f013	409	} else {
donatien	0:632c9925f013	410
donatien	0:632c9925f013	411	/* If no matching PCB was found, send a TCP RST (reset) to the
donatien	0:632c9925f013	412	sender. */
donatien	0:632c9925f013	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
donatien	0:632c9925f013	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
donatien	0:632c9925f013	415	TCP_STATS_INC(tcp.proterr);
donatien	0:632c9925f013	416	TCP_STATS_INC(tcp.drop);
donatien	0:632c9925f013	417	tcp_rst(ackno, seqno + tcplen,
donatien	5:dd63a1e02b1b	418	ip_current_dest_addr(), ip_current_src_addr(),
donatien	0:632c9925f013	419	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	420	}
donatien	0:632c9925f013	421	pbuf_free(p);
donatien	0:632c9925f013	422	}
donatien	0:632c9925f013	423
donatien	0:632c9925f013	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
donatien	0:632c9925f013	425	PERF_STOP("tcp_input");
donatien	0:632c9925f013	426	}
donatien	0:632c9925f013	427
donatien	0:632c9925f013	428	/**
donatien	0:632c9925f013	429	* Called by tcp_input() when a segment arrives for a listening
donatien	0:632c9925f013	430	* connection (from tcp_input()).
donatien	0:632c9925f013	431	*
donatien	0:632c9925f013	432	* @param pcb the tcp_pcb_listen for which a segment arrived
donatien	0:632c9925f013	433	* @return ERR_OK if the segment was processed
donatien	0:632c9925f013	434	* another err_t on error
donatien	0:632c9925f013	435	*
donatien	0:632c9925f013	436	* @note the return value is not (yet?) used in tcp_input()
donatien	0:632c9925f013	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
donatien	0:632c9925f013	438	* involved is passed as a parameter to this function
donatien	0:632c9925f013	439	*/
donatien	0:632c9925f013	440	static err_t
donatien	0:632c9925f013	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
donatien	0:632c9925f013	442	{
donatien	0:632c9925f013	443	struct tcp_pcb *npcb;
donatien	0:632c9925f013	444	err_t rc;
donatien	0:632c9925f013	445
donatien	0:632c9925f013	446	/* In the LISTEN state, we check for incoming SYN segments,
donatien	0:632c9925f013	447	creates a new PCB, and responds with a SYN\|ACK. */
donatien	0:632c9925f013	448	if (flags & TCP_ACK) {
donatien	0:632c9925f013	449	/* For incoming segments with the ACK flag set, respond with a
donatien	0:632c9925f013	450	RST. */
donatien	0:632c9925f013	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
donatien	0:632c9925f013	452	tcp_rst(ackno + 1, seqno + tcplen,
donatien	5:dd63a1e02b1b	453	ip_current_dest_addr(), ip_current_src_addr(),
donatien	0:632c9925f013	454	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	455	} else if (flags & TCP_SYN) {
donatien	0:632c9925f013	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
donatien	0:632c9925f013	457	#if TCP_LISTEN_BACKLOG
donatien	0:632c9925f013	458	if (pcb->accepts_pending >= pcb->backlog) {
donatien	0:632c9925f013	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
donatien	0:632c9925f013	460	return ERR_ABRT;
donatien	0:632c9925f013	461	}
donatien	0:632c9925f013	462	#endif /* TCP_LISTEN_BACKLOG */
donatien	0:632c9925f013	463	npcb = tcp_alloc(pcb->prio);
donatien	0:632c9925f013	464	/* If a new PCB could not be created (probably due to lack of memory),
donatien	0:632c9925f013	465	we don't do anything, but rely on the sender will retransmit the
donatien	0:632c9925f013	466	SYN at a time when we have more memory available. */
donatien	0:632c9925f013	467	if (npcb == NULL) {
donatien	0:632c9925f013	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
donatien	0:632c9925f013	469	TCP_STATS_INC(tcp.memerr);
donatien	0:632c9925f013	470	return ERR_MEM;
donatien	0:632c9925f013	471	}
donatien	0:632c9925f013	472	#if TCP_LISTEN_BACKLOG
donatien	0:632c9925f013	473	pcb->accepts_pending++;
donatien	0:632c9925f013	474	#endif /* TCP_LISTEN_BACKLOG */
donatien	0:632c9925f013	475	/* Set up the new PCB. */
donatien	5:dd63a1e02b1b	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
donatien	0:632c9925f013	477	npcb->local_port = pcb->local_port;
donatien	5:dd63a1e02b1b	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
donatien	0:632c9925f013	479	npcb->remote_port = tcphdr->src;
donatien	0:632c9925f013	480	npcb->state = SYN_RCVD;
donatien	0:632c9925f013	481	npcb->rcv_nxt = seqno + 1;
donatien	0:632c9925f013	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
donatien	0:632c9925f013	483	npcb->snd_wnd = tcphdr->wnd;
donatien	0:632c9925f013	484	npcb->ssthresh = npcb->snd_wnd;
donatien	0:632c9925f013	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
donatien	0:632c9925f013	486	npcb->callback_arg = pcb->callback_arg;
donatien	0:632c9925f013	487	#if LWIP_CALLBACK_API
donatien	0:632c9925f013	488	npcb->accept = pcb->accept;
donatien	0:632c9925f013	489	#endif /* LWIP_CALLBACK_API */
donatien	0:632c9925f013	490	/* inherit socket options */
donatien	5:dd63a1e02b1b	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
donatien	0:632c9925f013	492	/* Register the new PCB so that we can begin receiving segments
donatien	0:632c9925f013	493	for it. */
donatien	0:632c9925f013	494	TCP_REG(&tcp_active_pcbs, npcb);
donatien	0:632c9925f013	495
donatien	0:632c9925f013	496	/* Parse any options in the SYN. */
donatien	0:632c9925f013	497	tcp_parseopt(npcb);
donatien	0:632c9925f013	498	#if TCP_CALCULATE_EFF_SEND_MSS
donatien	0:632c9925f013	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
donatien	0:632c9925f013	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
donatien	0:632c9925f013	501
donatien	0:632c9925f013	502	snmp_inc_tcppassiveopens();
donatien	0:632c9925f013	503
donatien	0:632c9925f013	504	/* Send a SYN\|ACK together with the MSS option. */
donatien	0:632c9925f013	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
donatien	0:632c9925f013	506	if (rc != ERR_OK) {
donatien	0:632c9925f013	507	tcp_abandon(npcb, 0);
donatien	0:632c9925f013	508	return rc;
donatien	0:632c9925f013	509	}
donatien	0:632c9925f013	510	return tcp_output(npcb);
donatien	0:632c9925f013	511	}
donatien	0:632c9925f013	512	return ERR_OK;
donatien	0:632c9925f013	513	}
donatien	0:632c9925f013	514
donatien	0:632c9925f013	515	/**
donatien	0:632c9925f013	516	* Called by tcp_input() when a segment arrives for a connection in
donatien	0:632c9925f013	517	* TIME_WAIT.
donatien	0:632c9925f013	518	*
donatien	0:632c9925f013	519	* @param pcb the tcp_pcb for which a segment arrived
donatien	0:632c9925f013	520	*
donatien	0:632c9925f013	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
donatien	0:632c9925f013	522	* involved is passed as a parameter to this function
donatien	0:632c9925f013	523	*/
donatien	0:632c9925f013	524	static err_t
donatien	0:632c9925f013	525	tcp_timewait_input(struct tcp_pcb *pcb)
donatien	0:632c9925f013	526	{
donatien	0:632c9925f013	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
donatien	0:632c9925f013	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
donatien	0:632c9925f013	529	* - first check sequence number - we skip that one in TIME_WAIT (always
donatien	0:632c9925f013	530	* acceptable since we only send ACKs)
donatien	0:632c9925f013	531	* - second check the RST bit (... return) */
donatien	0:632c9925f013	532	if (flags & TCP_RST) {
donatien	0:632c9925f013	533	return ERR_OK;
donatien	0:632c9925f013	534	}
donatien	0:632c9925f013	535	/* - fourth, check the SYN bit, */
donatien	0:632c9925f013	536	if (flags & TCP_SYN) {
donatien	0:632c9925f013	537	/* If an incoming segment is not acceptable, an acknowledgment
donatien	0:632c9925f013	538	should be sent in reply */
donatien	0:632c9925f013	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
donatien	0:632c9925f013	540	/* If the SYN is in the window it is an error, send a reset */
donatien	5:dd63a1e02b1b	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
donatien	0:632c9925f013	542	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	543	return ERR_OK;
donatien	0:632c9925f013	544	}
donatien	0:632c9925f013	545	} else if (flags & TCP_FIN) {
donatien	0:632c9925f013	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
donatien	0:632c9925f013	547	Restart the 2 MSL time-wait timeout.*/
donatien	0:632c9925f013	548	pcb->tmr = tcp_ticks;
donatien	0:632c9925f013	549	}
donatien	0:632c9925f013	550
donatien	0:632c9925f013	551	if ((tcplen > 0)) {
donatien	0:632c9925f013	552	/* Acknowledge data, FIN or out-of-window SYN */
donatien	0:632c9925f013	553	pcb->flags \|= TF_ACK_NOW;
donatien	0:632c9925f013	554	return tcp_output(pcb);
donatien	0:632c9925f013	555	}
donatien	0:632c9925f013	556	return ERR_OK;
donatien	0:632c9925f013	557	}
donatien	0:632c9925f013	558
donatien	0:632c9925f013	559	/**
donatien	0:632c9925f013	560	* Implements the TCP state machine. Called by tcp_input. In some
donatien	0:632c9925f013	561	* states tcp_receive() is called to receive data. The tcp_seg
donatien	0:632c9925f013	562	* argument will be freed by the caller (tcp_input()) unless the
donatien	0:632c9925f013	563	* recv_data pointer in the pcb is set.
donatien	0:632c9925f013	564	*
donatien	0:632c9925f013	565	* @param pcb the tcp_pcb for which a segment arrived
donatien	0:632c9925f013	566	*
donatien	0:632c9925f013	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
donatien	0:632c9925f013	568	* involved is passed as a parameter to this function
donatien	0:632c9925f013	569	*/
donatien	0:632c9925f013	570	static err_t
donatien	0:632c9925f013	571	tcp_process(struct tcp_pcb *pcb)
donatien	0:632c9925f013	572	{
donatien	0:632c9925f013	573	struct tcp_seg *rseg;
donatien	0:632c9925f013	574	u8_t acceptable = 0;
donatien	0:632c9925f013	575	err_t err;
donatien	0:632c9925f013	576
donatien	0:632c9925f013	577	err = ERR_OK;
donatien	0:632c9925f013	578
donatien	0:632c9925f013	579	/* Process incoming RST segments. */
donatien	0:632c9925f013	580	if (flags & TCP_RST) {
donatien	0:632c9925f013	581	/* First, determine if the reset is acceptable. */
donatien	0:632c9925f013	582	if (pcb->state == SYN_SENT) {
donatien	0:632c9925f013	583	if (ackno == pcb->snd_nxt) {
donatien	0:632c9925f013	584	acceptable = 1;
donatien	0:632c9925f013	585	}
donatien	0:632c9925f013	586	} else {
donatien	0:632c9925f013	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
donatien	0:632c9925f013	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
donatien	0:632c9925f013	589	acceptable = 1;
donatien	0:632c9925f013	590	}
donatien	0:632c9925f013	591	}
donatien	0:632c9925f013	592
donatien	0:632c9925f013	593	if (acceptable) {
donatien	0:632c9925f013	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
donatien	0:632c9925f013	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
donatien	0:632c9925f013	596	recv_flags \|= TF_RESET;
donatien	0:632c9925f013	597	pcb->flags &= ~TF_ACK_DELAY;
donatien	0:632c9925f013	598	return ERR_RST;
donatien	0:632c9925f013	599	} else {
donatien	0:632c9925f013	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
donatien	0:632c9925f013	601	seqno, pcb->rcv_nxt));
donatien	0:632c9925f013	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
donatien	0:632c9925f013	603	seqno, pcb->rcv_nxt));
donatien	0:632c9925f013	604	return ERR_OK;
donatien	0:632c9925f013	605	}
donatien	0:632c9925f013	606	}
donatien	0:632c9925f013	607
donatien	0:632c9925f013	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
donatien	0:632c9925f013	609	/* Cope with new connection attempt after remote end crashed */
donatien	0:632c9925f013	610	tcp_ack_now(pcb);
donatien	0:632c9925f013	611	return ERR_OK;
donatien	0:632c9925f013	612	}
donatien	0:632c9925f013	613
donatien	0:632c9925f013	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
donatien	0:632c9925f013	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
donatien	0:632c9925f013	616	pcb->tmr = tcp_ticks;
donatien	0:632c9925f013	617	}
donatien	0:632c9925f013	618	pcb->keep_cnt_sent = 0;
donatien	0:632c9925f013	619
donatien	0:632c9925f013	620	tcp_parseopt(pcb);
donatien	0:632c9925f013	621
donatien	0:632c9925f013	622	/* Do different things depending on the TCP state. */
donatien	0:632c9925f013	623	switch (pcb->state) {
donatien	0:632c9925f013	624	case SYN_SENT:
donatien	0:632c9925f013	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
donatien	0:632c9925f013	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
donatien	0:632c9925f013	627	/* received SYN ACK with expected sequence number? */
donatien	0:632c9925f013	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
donatien	0:632c9925f013	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
donatien	0:632c9925f013	630	pcb->snd_buf++;
donatien	0:632c9925f013	631	pcb->rcv_nxt = seqno + 1;
donatien	0:632c9925f013	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
donatien	0:632c9925f013	633	pcb->lastack = ackno;
donatien	0:632c9925f013	634	pcb->snd_wnd = tcphdr->wnd;
donatien	0:632c9925f013	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
donatien	0:632c9925f013	636	pcb->state = ESTABLISHED;
donatien	0:632c9925f013	637
donatien	0:632c9925f013	638	#if TCP_CALCULATE_EFF_SEND_MSS
donatien	0:632c9925f013	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
donatien	0:632c9925f013	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
donatien	0:632c9925f013	641
donatien	0:632c9925f013	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
donatien	0:632c9925f013	643	* but for the default value of pcb->mss) */
donatien	0:632c9925f013	644	pcb->ssthresh = pcb->mss * 10;
donatien	0:632c9925f013	645
donatien	0:632c9925f013	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
donatien	0:632c9925f013	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
donatien	0:632c9925f013	648	--pcb->snd_queuelen;
donatien	0:632c9925f013	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	650	rseg = pcb->unacked;
donatien	0:632c9925f013	651	pcb->unacked = rseg->next;
donatien	0:632c9925f013	652
donatien	0:632c9925f013	653	/* If there's nothing left to acknowledge, stop the retransmit
donatien	0:632c9925f013	654	timer, otherwise reset it to start again */
donatien	0:632c9925f013	655	if(pcb->unacked == NULL)
donatien	0:632c9925f013	656	pcb->rtime = -1;
donatien	0:632c9925f013	657	else {
donatien	0:632c9925f013	658	pcb->rtime = 0;
donatien	0:632c9925f013	659	pcb->nrtx = 0;
donatien	0:632c9925f013	660	}
donatien	0:632c9925f013	661
donatien	0:632c9925f013	662	tcp_seg_free(rseg);
donatien	0:632c9925f013	663
donatien	0:632c9925f013	664	/* Call the user specified function to call when sucessfully
donatien	0:632c9925f013	665	* connected. */
donatien	0:632c9925f013	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
donatien	0:632c9925f013	667	if (err == ERR_ABRT) {
donatien	0:632c9925f013	668	return ERR_ABRT;
donatien	0:632c9925f013	669	}
donatien	0:632c9925f013	670	tcp_ack_now(pcb);
donatien	0:632c9925f013	671	}
donatien	0:632c9925f013	672	/* received ACK? possibly a half-open connection */
donatien	0:632c9925f013	673	else if (flags & TCP_ACK) {
donatien	0:632c9925f013	674	/* send a RST to bring the other side in a non-synchronized state. */
donatien	5:dd63a1e02b1b	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
donatien	0:632c9925f013	676	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	677	}
donatien	0:632c9925f013	678	break;
donatien	0:632c9925f013	679	case SYN_RCVD:
donatien	0:632c9925f013	680	if (flags & TCP_ACK) {
donatien	0:632c9925f013	681	/* expected ACK number? */
donatien	0:632c9925f013	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
donatien	0:632c9925f013	683	u16_t old_cwnd;
donatien	0:632c9925f013	684	pcb->state = ESTABLISHED;
donatien	0:632c9925f013	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	686	#if LWIP_CALLBACK_API
donatien	0:632c9925f013	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
donatien	0:632c9925f013	688	#endif
donatien	0:632c9925f013	689	/* Call the accept function. */
donatien	0:632c9925f013	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
donatien	0:632c9925f013	691	if (err != ERR_OK) {
donatien	0:632c9925f013	692	/* If the accept function returns with an error, we abort
donatien	0:632c9925f013	693	* the connection. */
donatien	0:632c9925f013	694	/* Already aborted? */
donatien	0:632c9925f013	695	if (err != ERR_ABRT) {
donatien	0:632c9925f013	696	tcp_abort(pcb);
donatien	0:632c9925f013	697	}
donatien	0:632c9925f013	698	return ERR_ABRT;
donatien	0:632c9925f013	699	}
donatien	0:632c9925f013	700	old_cwnd = pcb->cwnd;
donatien	0:632c9925f013	701	/* If there was any data contained within this ACK,
donatien	0:632c9925f013	702	* we'd better pass it on to the application as well. */
donatien	0:632c9925f013	703	tcp_receive(pcb);
donatien	0:632c9925f013	704
donatien	0:632c9925f013	705	/* Prevent ACK for SYN to generate a sent event */
donatien	0:632c9925f013	706	if (pcb->acked != 0) {
donatien	0:632c9925f013	707	pcb->acked--;
donatien	0:632c9925f013	708	}
donatien	0:632c9925f013	709
donatien	0:632c9925f013	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
donatien	0:632c9925f013	711
donatien	0:632c9925f013	712	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	713	tcp_ack_now(pcb);
donatien	0:632c9925f013	714	pcb->state = CLOSE_WAIT;
donatien	0:632c9925f013	715	}
donatien	0:632c9925f013	716	} else {
donatien	0:632c9925f013	717	/* incorrect ACK number, send RST */
donatien	5:dd63a1e02b1b	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
donatien	0:632c9925f013	719	tcphdr->dest, tcphdr->src);
donatien	0:632c9925f013	720	}
donatien	0:632c9925f013	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
donatien	0:632c9925f013	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
donatien	0:632c9925f013	723	tcp_rexmit(pcb);
donatien	0:632c9925f013	724	}
donatien	0:632c9925f013	725	break;
donatien	0:632c9925f013	726	case CLOSE_WAIT:
donatien	0:632c9925f013	727	/* FALLTHROUGH */
donatien	0:632c9925f013	728	case ESTABLISHED:
donatien	0:632c9925f013	729	tcp_receive(pcb);
donatien	0:632c9925f013	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
donatien	0:632c9925f013	731	tcp_ack_now(pcb);
donatien	0:632c9925f013	732	pcb->state = CLOSE_WAIT;
donatien	0:632c9925f013	733	}
donatien	0:632c9925f013	734	break;
donatien	0:632c9925f013	735	case FIN_WAIT_1:
donatien	0:632c9925f013	736	tcp_receive(pcb);
donatien	0:632c9925f013	737	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
donatien	0:632c9925f013	739	LWIP_DEBUGF(TCP_DEBUG,
donatien	0:632c9925f013	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	741	tcp_ack_now(pcb);
donatien	0:632c9925f013	742	tcp_pcb_purge(pcb);
donatien	0:632c9925f013	743	TCP_RMV(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	744	pcb->state = TIME_WAIT;
donatien	0:632c9925f013	745	TCP_REG(&tcp_tw_pcbs, pcb);
donatien	0:632c9925f013	746	} else {
donatien	0:632c9925f013	747	tcp_ack_now(pcb);
donatien	0:632c9925f013	748	pcb->state = CLOSING;
donatien	0:632c9925f013	749	}
donatien	0:632c9925f013	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
donatien	0:632c9925f013	751	pcb->state = FIN_WAIT_2;
donatien	0:632c9925f013	752	}
donatien	0:632c9925f013	753	break;
donatien	0:632c9925f013	754	case FIN_WAIT_2:
donatien	0:632c9925f013	755	tcp_receive(pcb);
donatien	0:632c9925f013	756	if (recv_flags & TF_GOT_FIN) {
donatien	0:632c9925f013	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	758	tcp_ack_now(pcb);
donatien	0:632c9925f013	759	tcp_pcb_purge(pcb);
donatien	0:632c9925f013	760	TCP_RMV(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	761	pcb->state = TIME_WAIT;
donatien	0:632c9925f013	762	TCP_REG(&tcp_tw_pcbs, pcb);
donatien	0:632c9925f013	763	}
donatien	0:632c9925f013	764	break;
donatien	0:632c9925f013	765	case CLOSING:
donatien	0:632c9925f013	766	tcp_receive(pcb);
donatien	0:632c9925f013	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
donatien	0:632c9925f013	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	769	tcp_pcb_purge(pcb);
donatien	0:632c9925f013	770	TCP_RMV(&tcp_active_pcbs, pcb);
donatien	0:632c9925f013	771	pcb->state = TIME_WAIT;
donatien	0:632c9925f013	772	TCP_REG(&tcp_tw_pcbs, pcb);
donatien	0:632c9925f013	773	}
donatien	0:632c9925f013	774	break;
donatien	0:632c9925f013	775	case LAST_ACK:
donatien	0:632c9925f013	776	tcp_receive(pcb);
donatien	0:632c9925f013	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
donatien	0:632c9925f013	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
donatien	0:632c9925f013	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
donatien	0:632c9925f013	780	recv_flags \|= TF_CLOSED;
donatien	0:632c9925f013	781	}
donatien	0:632c9925f013	782	break;
donatien	0:632c9925f013	783	default:
donatien	0:632c9925f013	784	break;
donatien	0:632c9925f013	785	}
donatien	0:632c9925f013	786	return ERR_OK;
donatien	0:632c9925f013	787	}
donatien	0:632c9925f013	788
donatien	0:632c9925f013	789	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	790	/**
donatien	0:632c9925f013	791	* Insert segment into the list (segments covered with new one will be deleted)
donatien	0:632c9925f013	792	*
donatien	0:632c9925f013	793	* Called from tcp_receive()
donatien	0:632c9925f013	794	*/
donatien	0:632c9925f013	795	static void
donatien	0:632c9925f013	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
donatien	0:632c9925f013	797	{
donatien	0:632c9925f013	798	struct tcp_seg *old_seg;
donatien	0:632c9925f013	799
donatien	0:632c9925f013	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	801	/* received segment overlaps all following segments */
donatien	0:632c9925f013	802	tcp_segs_free(next);
donatien	0:632c9925f013	803	next = NULL;
donatien	0:632c9925f013	804	}
donatien	0:632c9925f013	805	else {
donatien	0:632c9925f013	806	/* delete some following segments
donatien	0:632c9925f013	807	oos queue may have segments with FIN flag */
donatien	0:632c9925f013	808	while (next &&
donatien	0:632c9925f013	809	TCP_SEQ_GEQ((seqno + cseg->len),
donatien	0:632c9925f013	810	(next->tcphdr->seqno + next->len))) {
donatien	0:632c9925f013	811	/* cseg with FIN already processed */
donatien	0:632c9925f013	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
donatien	0:632c9925f013	814	}
donatien	0:632c9925f013	815	old_seg = next;
donatien	0:632c9925f013	816	next = next->next;
donatien	0:632c9925f013	817	tcp_seg_free(old_seg);
donatien	0:632c9925f013	818	}
donatien	0:632c9925f013	819	if (next &&
donatien	0:632c9925f013	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
donatien	0:632c9925f013	821	/* We need to trim the incoming segment. */
donatien	0:632c9925f013	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
donatien	0:632c9925f013	823	pbuf_realloc(cseg->p, cseg->len);
donatien	0:632c9925f013	824	}
donatien	0:632c9925f013	825	}
donatien	0:632c9925f013	826	cseg->next = next;
donatien	0:632c9925f013	827	}
donatien	0:632c9925f013	828	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	829
donatien	0:632c9925f013	830	/**
donatien	0:632c9925f013	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
donatien	0:632c9925f013	832	* data, and if so frees the memory of the buffered data. Next, is places the
donatien	0:632c9925f013	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
donatien	0:632c9925f013	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
donatien	0:632c9925f013	835	* i it has been removed from the buffer.
donatien	0:632c9925f013	836	*
donatien	0:632c9925f013	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
donatien	0:632c9925f013	838	* estimation, the RTT is estimated here as well.
donatien	0:632c9925f013	839	*
donatien	0:632c9925f013	840	* Called from tcp_process().
donatien	0:632c9925f013	841	*/
donatien	0:632c9925f013	842	static void
donatien	0:632c9925f013	843	tcp_receive(struct tcp_pcb *pcb)
donatien	0:632c9925f013	844	{
donatien	0:632c9925f013	845	struct tcp_seg *next;
donatien	0:632c9925f013	846	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	847	struct tcp_seg prev, cseg;
donatien	0:632c9925f013	848	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	849	struct pbuf *p;
donatien	0:632c9925f013	850	s32_t off;
donatien	0:632c9925f013	851	s16_t m;
donatien	0:632c9925f013	852	u32_t right_wnd_edge;
donatien	0:632c9925f013	853	u16_t new_tot_len;
donatien	0:632c9925f013	854	int found_dupack = 0;
donatien	0:632c9925f013	855
donatien	0:632c9925f013	856	if (flags & TCP_ACK) {
donatien	0:632c9925f013	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
donatien	0:632c9925f013	858
donatien	0:632c9925f013	859	/* Update window. */
donatien	0:632c9925f013	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
donatien	0:632c9925f013	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
donatien	0:632c9925f013	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
donatien	0:632c9925f013	863	pcb->snd_wnd = tcphdr->wnd;
donatien	0:632c9925f013	864	pcb->snd_wl1 = seqno;
donatien	0:632c9925f013	865	pcb->snd_wl2 = ackno;
donatien	0:632c9925f013	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
donatien	0:632c9925f013	867	pcb->persist_backoff = 0;
donatien	0:632c9925f013	868	}
donatien	0:632c9925f013	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
donatien	0:632c9925f013	870	#if TCP_WND_DEBUG
donatien	0:632c9925f013	871	} else {
donatien	0:632c9925f013	872	if (pcb->snd_wnd != tcphdr->wnd) {
donatien	0:632c9925f013	873	LWIP_DEBUGF(TCP_WND_DEBUG,
donatien	0:632c9925f013	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
donatien	0:632c9925f013	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
donatien	0:632c9925f013	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
donatien	0:632c9925f013	877	}
donatien	0:632c9925f013	878	#endif /* TCP_WND_DEBUG */
donatien	0:632c9925f013	879	}
donatien	0:632c9925f013	880
donatien	0:632c9925f013	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
donatien	0:632c9925f013	882	* duplicate ack if:
donatien	0:632c9925f013	883	* 1) It doesn't ACK new data
donatien	0:632c9925f013	884	* 2) length of received packet is zero (i.e. no payload)
donatien	0:632c9925f013	885	* 3) the advertised window hasn't changed
donatien	0:632c9925f013	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
donatien	0:632c9925f013	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
donatien	0:632c9925f013	888	*
donatien	0:632c9925f013	889	* If it passes all five, should process as a dupack:
donatien	0:632c9925f013	890	* a) dupacks < 3: do nothing
donatien	0:632c9925f013	891	* b) dupacks == 3: fast retransmit
donatien	0:632c9925f013	892	* c) dupacks > 3: increase cwnd
donatien	0:632c9925f013	893	*
donatien	0:632c9925f013	894	* If it only passes 1-3, should reset dupack counter (and add to
donatien	0:632c9925f013	895	* stats, which we don't do in lwIP)
donatien	0:632c9925f013	896	*
donatien	0:632c9925f013	897	* If it only passes 1, should reset dupack counter
donatien	0:632c9925f013	898	*
donatien	0:632c9925f013	899	*/
donatien	0:632c9925f013	900
donatien	0:632c9925f013	901	/* Clause 1 */
donatien	0:632c9925f013	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
donatien	0:632c9925f013	903	pcb->acked = 0;
donatien	0:632c9925f013	904	/* Clause 2 */
donatien	0:632c9925f013	905	if (tcplen == 0) {
donatien	0:632c9925f013	906	/* Clause 3 */
donatien	0:632c9925f013	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
donatien	0:632c9925f013	908	/* Clause 4 */
donatien	0:632c9925f013	909	if (pcb->rtime >= 0) {
donatien	0:632c9925f013	910	/* Clause 5 */
donatien	0:632c9925f013	911	if (pcb->lastack == ackno) {
donatien	0:632c9925f013	912	found_dupack = 1;
donatien	0:632c9925f013	913	if (pcb->dupacks + 1 > pcb->dupacks)
donatien	0:632c9925f013	914	++pcb->dupacks;
donatien	0:632c9925f013	915	if (pcb->dupacks > 3) {
donatien	0:632c9925f013	916	/* Inflate the congestion window, but not if it means that
donatien	0:632c9925f013	917	the value overflows. */
donatien	0:632c9925f013	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
donatien	0:632c9925f013	919	pcb->cwnd += pcb->mss;
donatien	0:632c9925f013	920	}
donatien	0:632c9925f013	921	} else if (pcb->dupacks == 3) {
donatien	0:632c9925f013	922	/* Do fast retransmit */
donatien	0:632c9925f013	923	tcp_rexmit_fast(pcb);
donatien	0:632c9925f013	924	}
donatien	0:632c9925f013	925	}
donatien	0:632c9925f013	926	}
donatien	0:632c9925f013	927	}
donatien	0:632c9925f013	928	}
donatien	0:632c9925f013	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
donatien	0:632c9925f013	930	* count of consecutive duplicate acks */
donatien	0:632c9925f013	931	if (!found_dupack) {
donatien	0:632c9925f013	932	pcb->dupacks = 0;
donatien	0:632c9925f013	933	}
donatien	0:632c9925f013	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
donatien	0:632c9925f013	935	/* We come here when the ACK acknowledges new data. */
donatien	0:632c9925f013	936
donatien	0:632c9925f013	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
donatien	0:632c9925f013	938	in fast retransmit. Also reset the congestion window to the
donatien	0:632c9925f013	939	slow start threshold. */
donatien	0:632c9925f013	940	if (pcb->flags & TF_INFR) {
donatien	0:632c9925f013	941	pcb->flags &= ~TF_INFR;
donatien	0:632c9925f013	942	pcb->cwnd = pcb->ssthresh;
donatien	0:632c9925f013	943	}
donatien	0:632c9925f013	944
donatien	0:632c9925f013	945	/* Reset the number of retransmissions. */
donatien	0:632c9925f013	946	pcb->nrtx = 0;
donatien	0:632c9925f013	947
donatien	0:632c9925f013	948	/* Reset the retransmission time-out. */
donatien	0:632c9925f013	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
donatien	0:632c9925f013	950
donatien	0:632c9925f013	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
donatien	0:632c9925f013	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
donatien	0:632c9925f013	953
donatien	0:632c9925f013	954	pcb->snd_buf += pcb->acked;
donatien	0:632c9925f013	955
donatien	0:632c9925f013	956	/* Reset the fast retransmit variables. */
donatien	0:632c9925f013	957	pcb->dupacks = 0;
donatien	0:632c9925f013	958	pcb->lastack = ackno;
donatien	0:632c9925f013	959
donatien	0:632c9925f013	960	/* Update the congestion control variables (cwnd and
donatien	0:632c9925f013	961	ssthresh). */
donatien	0:632c9925f013	962	if (pcb->state >= ESTABLISHED) {
donatien	0:632c9925f013	963	if (pcb->cwnd < pcb->ssthresh) {
donatien	0:632c9925f013	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
donatien	0:632c9925f013	965	pcb->cwnd += pcb->mss;
donatien	0:632c9925f013	966	}
donatien	0:632c9925f013	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
donatien	0:632c9925f013	968	} else {
donatien	0:632c9925f013	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
donatien	0:632c9925f013	970	if (new_cwnd > pcb->cwnd) {
donatien	0:632c9925f013	971	pcb->cwnd = new_cwnd;
donatien	0:632c9925f013	972	}
donatien	0:632c9925f013	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
donatien	0:632c9925f013	974	}
donatien	0:632c9925f013	975	}
donatien	0:632c9925f013	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
donatien	0:632c9925f013	977	ackno,
donatien	0:632c9925f013	978	pcb->unacked != NULL?
donatien	0:632c9925f013	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
donatien	0:632c9925f013	980	pcb->unacked != NULL?
donatien	0:632c9925f013	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
donatien	0:632c9925f013	982
donatien	0:632c9925f013	983	/* Remove segment from the unacknowledged list if the incoming
donatien	0:632c9925f013	984	ACK acknowlegdes them. */
donatien	0:632c9925f013	985	while (pcb->unacked != NULL &&
donatien	0:632c9925f013	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
donatien	0:632c9925f013	987	TCP_TCPLEN(pcb->unacked), ackno)) {
donatien	0:632c9925f013	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
donatien	0:632c9925f013	989	ntohl(pcb->unacked->tcphdr->seqno),
donatien	0:632c9925f013	990	ntohl(pcb->unacked->tcphdr->seqno) +
donatien	0:632c9925f013	991	TCP_TCPLEN(pcb->unacked)));
donatien	0:632c9925f013	992
donatien	0:632c9925f013	993	next = pcb->unacked;
donatien	0:632c9925f013	994	pcb->unacked = pcb->unacked->next;
donatien	0:632c9925f013	995
donatien	0:632c9925f013	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
donatien	0:632c9925f013	998	/* Prevent ACK for FIN to generate a sent event */
donatien	0:632c9925f013	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
donatien	0:632c9925f013	1000	pcb->acked--;
donatien	0:632c9925f013	1001	}
donatien	0:632c9925f013	1002
donatien	0:632c9925f013	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
donatien	0:632c9925f013	1004	tcp_seg_free(next);
donatien	0:632c9925f013	1005
donatien	0:632c9925f013	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	1007	if (pcb->snd_queuelen != 0) {
donatien	0:632c9925f013	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
donatien	0:632c9925f013	1009	pcb->unsent != NULL);
donatien	0:632c9925f013	1010	}
donatien	0:632c9925f013	1011	}
donatien	0:632c9925f013	1012
donatien	0:632c9925f013	1013	/* If there's nothing left to acknowledge, stop the retransmit
donatien	0:632c9925f013	1014	timer, otherwise reset it to start again */
donatien	0:632c9925f013	1015	if(pcb->unacked == NULL)
donatien	0:632c9925f013	1016	pcb->rtime = -1;
donatien	0:632c9925f013	1017	else
donatien	0:632c9925f013	1018	pcb->rtime = 0;
donatien	0:632c9925f013	1019
donatien	0:632c9925f013	1020	pcb->polltmr = 0;
donatien	0:632c9925f013	1021	} else {
donatien	0:632c9925f013	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
donatien	0:632c9925f013	1023	pcb->acked = 0;
donatien	0:632c9925f013	1024	}
donatien	0:632c9925f013	1025
donatien	0:632c9925f013	1026	/* We go through the ->unsent list to see if any of the segments
donatien	0:632c9925f013	1027	on the list are acknowledged by the ACK. This may seem
donatien	0:632c9925f013	1028	strange since an "unsent" segment shouldn't be acked. The
donatien	0:632c9925f013	1029	rationale is that lwIP puts all outstanding segments on the
donatien	0:632c9925f013	1030	->unsent list after a retransmission, so these segments may
donatien	0:632c9925f013	1031	in fact have been sent once. */
donatien	0:632c9925f013	1032	while (pcb->unsent != NULL &&
donatien	0:632c9925f013	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
donatien	0:632c9925f013	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
donatien	0:632c9925f013	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
donatien	0:632c9925f013	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
donatien	0:632c9925f013	1037	TCP_TCPLEN(pcb->unsent)));
donatien	0:632c9925f013	1038
donatien	0:632c9925f013	1039	next = pcb->unsent;
donatien	0:632c9925f013	1040	pcb->unsent = pcb->unsent->next;
donatien	0:632c9925f013	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
donatien	0:632c9925f013	1043	/* Prevent ACK for FIN to generate a sent event */
donatien	0:632c9925f013	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
donatien	0:632c9925f013	1045	pcb->acked--;
donatien	0:632c9925f013	1046	}
donatien	0:632c9925f013	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
donatien	0:632c9925f013	1048	tcp_seg_free(next);
donatien	0:632c9925f013	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
donatien	0:632c9925f013	1050	if (pcb->snd_queuelen != 0) {
donatien	0:632c9925f013	1051	LWIP_ASSERT("tcp_receive: valid queue length",
donatien	0:632c9925f013	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
donatien	0:632c9925f013	1053	}
donatien	0:632c9925f013	1054	}
donatien	0:632c9925f013	1055	/* End of ACK for new data processing. */
donatien	0:632c9925f013	1056
donatien	0:632c9925f013	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
donatien	0:632c9925f013	1058	pcb->rttest, pcb->rtseq, ackno));
donatien	0:632c9925f013	1059
donatien	0:632c9925f013	1060	/* RTT estimation calculations. This is done by checking if the
donatien	0:632c9925f013	1061	incoming segment acknowledges the segment we use to take a
donatien	0:632c9925f013	1062	round-trip time measurement. */
donatien	0:632c9925f013	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
donatien	0:632c9925f013	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
donatien	0:632c9925f013	1065	and a round-trip shouldn't be that long... */
donatien	0:632c9925f013	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
donatien	0:632c9925f013	1067
donatien	0:632c9925f013	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
donatien	0:632c9925f013	1069	m, m * TCP_SLOW_INTERVAL));
donatien	0:632c9925f013	1070
donatien	0:632c9925f013	1071	/* This is taken directly from VJs original code in his paper */
donatien	0:632c9925f013	1072	m = m - (pcb->sa >> 3);
donatien	0:632c9925f013	1073	pcb->sa += m;
donatien	0:632c9925f013	1074	if (m < 0) {
donatien	0:632c9925f013	1075	m = -m;
donatien	0:632c9925f013	1076	}
donatien	0:632c9925f013	1077	m = m - (pcb->sv >> 2);
donatien	0:632c9925f013	1078	pcb->sv += m;
donatien	0:632c9925f013	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
donatien	0:632c9925f013	1080
donatien	0:632c9925f013	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
donatien	0:632c9925f013	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
donatien	0:632c9925f013	1083
donatien	0:632c9925f013	1084	pcb->rttest = 0;
donatien	0:632c9925f013	1085	}
donatien	0:632c9925f013	1086	}
donatien	0:632c9925f013	1087
donatien	0:632c9925f013	1088	/* If the incoming segment contains data, we must process it
donatien	0:632c9925f013	1089	further. */
donatien	0:632c9925f013	1090	if (tcplen > 0) {
donatien	0:632c9925f013	1091	/* This code basically does three things:
donatien	0:632c9925f013	1092
donatien	0:632c9925f013	1093	+) If the incoming segment contains data that is the next
donatien	0:632c9925f013	1094	in-sequence data, this data is passed to the application. This
donatien	0:632c9925f013	1095	might involve trimming the first edge of the data. The rcv_nxt
donatien	0:632c9925f013	1096	variable and the advertised window are adjusted.
donatien	0:632c9925f013	1097
donatien	0:632c9925f013	1098	+) If the incoming segment has data that is above the next
donatien	0:632c9925f013	1099	sequence number expected (->rcv_nxt), the segment is placed on
donatien	0:632c9925f013	1100	the ->ooseq queue. This is done by finding the appropriate
donatien	0:632c9925f013	1101	place in the ->ooseq queue (which is ordered by sequence
donatien	0:632c9925f013	1102	number) and trim the segment in both ends if needed. An
donatien	0:632c9925f013	1103	immediate ACK is sent to indicate that we received an
donatien	0:632c9925f013	1104	out-of-sequence segment.
donatien	0:632c9925f013	1105
donatien	0:632c9925f013	1106	+) Finally, we check if the first segment on the ->ooseq queue
donatien	0:632c9925f013	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
donatien	0:632c9925f013	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
donatien	0:632c9925f013	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
donatien	0:632c9925f013	1110	segments that are now on sequence are chained onto the
donatien	0:632c9925f013	1111	incoming segment so that we only need to call the application
donatien	0:632c9925f013	1112	once.
donatien	0:632c9925f013	1113	*/
donatien	0:632c9925f013	1114
donatien	0:632c9925f013	1115	/* First, we check if we must trim the first edge. We have to do
donatien	0:632c9925f013	1116	this if the sequence number of the incoming segment is less
donatien	0:632c9925f013	1117	than rcv_nxt, and the sequence number plus the length of the
donatien	0:632c9925f013	1118	segment is larger than rcv_nxt. */
donatien	0:632c9925f013	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
donatien	0:632c9925f013	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
donatien	0:632c9925f013	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
donatien	0:632c9925f013	1122	/* Trimming the first edge is done by pushing the payload
donatien	0:632c9925f013	1123	pointer in the pbuf downwards. This is somewhat tricky since
donatien	0:632c9925f013	1124	we do not want to discard the full contents of the pbuf up to
donatien	0:632c9925f013	1125	the new starting point of the data since we have to keep the
donatien	0:632c9925f013	1126	TCP header which is present in the first pbuf in the chain.
donatien	0:632c9925f013	1127
donatien	0:632c9925f013	1128	What is done is really quite a nasty hack: the first pbuf in
donatien	0:632c9925f013	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
donatien	0:632c9925f013	1130	able to deallocate the whole pbuf, we cannot change this
donatien	0:632c9925f013	1131	inseg.p pointer to point to any of the later pbufs in the
donatien	0:632c9925f013	1132	chain. Instead, we point the ->payload pointer in the first
donatien	0:632c9925f013	1133	pbuf to data in one of the later pbufs. We also set the
donatien	0:632c9925f013	1134	inseg.data pointer to point to the right place. This way, the
donatien	0:632c9925f013	1135	->p pointer will still point to the first pbuf, but the
donatien	0:632c9925f013	1136	->p->payload pointer will point to data in another pbuf.
donatien	0:632c9925f013	1137
donatien	0:632c9925f013	1138	After we are done with adjusting the pbuf pointers we must
donatien	0:632c9925f013	1139	adjust the ->data pointer in the seg and the segment
donatien	0:632c9925f013	1140	length.*/
donatien	0:632c9925f013	1141
donatien	0:632c9925f013	1142	off = pcb->rcv_nxt - seqno;
donatien	0:632c9925f013	1143	p = inseg.p;
donatien	0:632c9925f013	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
donatien	0:632c9925f013	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
donatien	0:632c9925f013	1146	if (inseg.p->len < off) {
donatien	0:632c9925f013	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
donatien	0:632c9925f013	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
donatien	0:632c9925f013	1149	while (p->len < off) {
donatien	0:632c9925f013	1150	off -= p->len;
donatien	0:632c9925f013	1151	/* KJM following line changed (with addition of new_tot_len var)
donatien	0:632c9925f013	1152	to fix bug #9076
donatien	0:632c9925f013	1153	inseg.p->tot_len -= p->len; */
donatien	0:632c9925f013	1154	p->tot_len = new_tot_len;
donatien	0:632c9925f013	1155	p->len = 0;
donatien	0:632c9925f013	1156	p = p->next;
donatien	0:632c9925f013	1157	}
donatien	0:632c9925f013	1158	if(pbuf_header(p, (s16_t)-off)) {
donatien	0:632c9925f013	1159	/* Do we need to cope with this failing? Assert for now */
donatien	0:632c9925f013	1160	LWIP_ASSERT("pbuf_header failed", 0);
donatien	0:632c9925f013	1161	}
donatien	0:632c9925f013	1162	} else {
donatien	0:632c9925f013	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
donatien	0:632c9925f013	1164	/* Do we need to cope with this failing? Assert for now */
donatien	0:632c9925f013	1165	LWIP_ASSERT("pbuf_header failed", 0);
donatien	0:632c9925f013	1166	}
donatien	0:632c9925f013	1167	}
donatien	0:632c9925f013	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
donatien	0:632c9925f013	1169	to fix bug #9076 */
donatien	0:632c9925f013	1170	inseg.dataptr = p->payload;
donatien	0:632c9925f013	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
donatien	0:632c9925f013	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
donatien	0:632c9925f013	1173	}
donatien	0:632c9925f013	1174	else {
donatien	0:632c9925f013	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
donatien	0:632c9925f013	1176	/* the whole segment is < rcv_nxt */
donatien	0:632c9925f013	1177	/* must be a duplicate of a packet that has already been correctly handled */
donatien	0:632c9925f013	1178
donatien	0:632c9925f013	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
donatien	0:632c9925f013	1180	tcp_ack_now(pcb);
donatien	0:632c9925f013	1181	}
donatien	0:632c9925f013	1182	}
donatien	0:632c9925f013	1183
donatien	0:632c9925f013	1184	/* The sequence number must be within the window (above rcv_nxt
donatien	0:632c9925f013	1185	and below rcv_nxt + rcv_wnd) in order to be further
donatien	0:632c9925f013	1186	processed. */
donatien	0:632c9925f013	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
donatien	0:632c9925f013	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
donatien	0:632c9925f013	1189	if (pcb->rcv_nxt == seqno) {
donatien	0:632c9925f013	1190	/* The incoming segment is the next in sequence. We check if
donatien	0:632c9925f013	1191	we have to trim the end of the segment and update rcv_nxt
donatien	0:632c9925f013	1192	and pass the data to the application. */
donatien	0:632c9925f013	1193	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1194
donatien	0:632c9925f013	1195	if (tcplen > pcb->rcv_wnd) {
donatien	0:632c9925f013	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
donatien	0:632c9925f013	1197	("tcp_receive: other end overran receive window"
donatien	0:632c9925f013	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
donatien	0:632c9925f013	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
donatien	0:632c9925f013	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1201	/* Must remove the FIN from the header as we're trimming
donatien	0:632c9925f013	1202	* that byte of sequence-space from the packet */
donatien	0:632c9925f013	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
donatien	0:632c9925f013	1204	}
donatien	0:632c9925f013	1205	/* Adjust length of segment to fit in the window. */
donatien	0:632c9925f013	1206	inseg.len = pcb->rcv_wnd;
donatien	0:632c9925f013	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
donatien	0:632c9925f013	1208	inseg.len -= 1;
donatien	0:632c9925f013	1209	}
donatien	0:632c9925f013	1210	pbuf_realloc(inseg.p, inseg.len);
donatien	0:632c9925f013	1211	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
donatien	0:632c9925f013	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
donatien	0:632c9925f013	1214	}
donatien	0:632c9925f013	1215	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	1216	/* Received in-sequence data, adjust ooseq data if:
donatien	0:632c9925f013	1217	- FIN has been received or
donatien	0:632c9925f013	1218	- inseq overlaps with ooseq */
donatien	0:632c9925f013	1219	if (pcb->ooseq != NULL) {
donatien	0:632c9925f013	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
donatien	0:632c9925f013	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
donatien	0:632c9925f013	1223	/* Received in-order FIN means anything that was received
donatien	0:632c9925f013	1224	* out of order must now have been received in-order, so
donatien	0:632c9925f013	1225	* bin the ooseq queue */
donatien	0:632c9925f013	1226	while (pcb->ooseq != NULL) {
donatien	0:632c9925f013	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
donatien	0:632c9925f013	1228	pcb->ooseq = pcb->ooseq->next;
donatien	0:632c9925f013	1229	tcp_seg_free(old_ooseq);
donatien	0:632c9925f013	1230	}
donatien	0:632c9925f013	1231	}
donatien	0:632c9925f013	1232	else {
donatien	0:632c9925f013	1233	next = pcb->ooseq;
donatien	0:632c9925f013	1234	/* Remove all segments on ooseq that are covered by inseg already.
donatien	0:632c9925f013	1235	* FIN is copied from ooseq to inseg if present. */
donatien	0:632c9925f013	1236	while (next &&
donatien	0:632c9925f013	1237	TCP_SEQ_GEQ(seqno + tcplen,
donatien	0:632c9925f013	1238	next->tcphdr->seqno + next->len)) {
donatien	0:632c9925f013	1239	/* inseg cannot have FIN here (already processed above) */
donatien	0:632c9925f013	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
donatien	0:632c9925f013	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
donatien	0:632c9925f013	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
donatien	0:632c9925f013	1243	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1244	}
donatien	0:632c9925f013	1245	prev = next;
donatien	0:632c9925f013	1246	next = next->next;
donatien	0:632c9925f013	1247	tcp_seg_free(prev);
donatien	0:632c9925f013	1248	}
donatien	0:632c9925f013	1249	/* Now trim right side of inseg if it overlaps with the first
donatien	0:632c9925f013	1250	* segment on ooseq */
donatien	0:632c9925f013	1251	if (next &&
donatien	0:632c9925f013	1252	TCP_SEQ_GT(seqno + tcplen,
donatien	0:632c9925f013	1253	next->tcphdr->seqno)) {
donatien	0:632c9925f013	1254	/* inseg cannot have FIN here (already processed above) */
donatien	0:632c9925f013	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
donatien	0:632c9925f013	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
donatien	0:632c9925f013	1257	inseg.len -= 1;
donatien	0:632c9925f013	1258	}
donatien	0:632c9925f013	1259	pbuf_realloc(inseg.p, inseg.len);
donatien	0:632c9925f013	1260	tcplen = TCP_TCPLEN(&inseg);
donatien	0:632c9925f013	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
donatien	0:632c9925f013	1262	(seqno + tcplen) == next->tcphdr->seqno);
donatien	0:632c9925f013	1263	}
donatien	0:632c9925f013	1264	pcb->ooseq = next;
donatien	0:632c9925f013	1265	}
donatien	0:632c9925f013	1266	}
donatien	0:632c9925f013	1267	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	1268
donatien	0:632c9925f013	1269	pcb->rcv_nxt = seqno + tcplen;
donatien	0:632c9925f013	1270
donatien	0:632c9925f013	1271	/* Update the receiver's (our) window. */
donatien	0:632c9925f013	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
donatien	0:632c9925f013	1273	pcb->rcv_wnd -= tcplen;
donatien	0:632c9925f013	1274
donatien	0:632c9925f013	1275	tcp_update_rcv_ann_wnd(pcb);
donatien	0:632c9925f013	1276
donatien	0:632c9925f013	1277	/* If there is data in the segment, we make preparations to
donatien	0:632c9925f013	1278	pass this up to the application. The ->recv_data variable
donatien	0:632c9925f013	1279	is used for holding the pbuf that goes to the
donatien	0:632c9925f013	1280	application. The code for reassembling out-of-sequence data
donatien	0:632c9925f013	1281	chains its data on this pbuf as well.
donatien	0:632c9925f013	1282
donatien	0:632c9925f013	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
donatien	0:632c9925f013	1284	be used to indicate to the application that the remote side has
donatien	0:632c9925f013	1285	closed its end of the connection. */
donatien	0:632c9925f013	1286	if (inseg.p->tot_len > 0) {
donatien	0:632c9925f013	1287	recv_data = inseg.p;
donatien	0:632c9925f013	1288	/* Since this pbuf now is the responsibility of the
donatien	0:632c9925f013	1289	application, we delete our reference to it so that we won't
donatien	0:632c9925f013	1290	(mistakingly) deallocate it. */
donatien	0:632c9925f013	1291	inseg.p = NULL;
donatien	0:632c9925f013	1292	}
donatien	0:632c9925f013	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
donatien	0:632c9925f013	1295	recv_flags \|= TF_GOT_FIN;
donatien	0:632c9925f013	1296	}
donatien	0:632c9925f013	1297
donatien	0:632c9925f013	1298	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	1299	/* We now check if we have segments on the ->ooseq queue that
donatien	0:632c9925f013	1300	are now in sequence. */
donatien	0:632c9925f013	1301	while (pcb->ooseq != NULL &&
donatien	0:632c9925f013	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
donatien	0:632c9925f013	1303
donatien	0:632c9925f013	1304	cseg = pcb->ooseq;
donatien	0:632c9925f013	1305	seqno = pcb->ooseq->tcphdr->seqno;
donatien	0:632c9925f013	1306
donatien	0:632c9925f013	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
donatien	0:632c9925f013	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
donatien	0:632c9925f013	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
donatien	0:632c9925f013	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
donatien	0:632c9925f013	1311
donatien	0:632c9925f013	1312	tcp_update_rcv_ann_wnd(pcb);
donatien	0:632c9925f013	1313
donatien	0:632c9925f013	1314	if (cseg->p->tot_len > 0) {
donatien	0:632c9925f013	1315	/* Chain this pbuf onto the pbuf that we will pass to
donatien	0:632c9925f013	1316	the application. */
donatien	0:632c9925f013	1317	if (recv_data) {
donatien	0:632c9925f013	1318	pbuf_cat(recv_data, cseg->p);
donatien	0:632c9925f013	1319	} else {
donatien	0:632c9925f013	1320	recv_data = cseg->p;
donatien	0:632c9925f013	1321	}
donatien	0:632c9925f013	1322	cseg->p = NULL;
donatien	0:632c9925f013	1323	}
donatien	0:632c9925f013	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
donatien	0:632c9925f013	1326	recv_flags \|= TF_GOT_FIN;
donatien	0:632c9925f013	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
donatien	0:632c9925f013	1328	pcb->state = CLOSE_WAIT;
donatien	0:632c9925f013	1329	}
donatien	0:632c9925f013	1330	}
donatien	0:632c9925f013	1331
donatien	0:632c9925f013	1332	pcb->ooseq = cseg->next;
donatien	0:632c9925f013	1333	tcp_seg_free(cseg);
donatien	0:632c9925f013	1334	}
donatien	0:632c9925f013	1335	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	1336
donatien	0:632c9925f013	1337
donatien	0:632c9925f013	1338	/* Acknowledge the segment(s). */
donatien	0:632c9925f013	1339	tcp_ack(pcb);
donatien	0:632c9925f013	1340
donatien	0:632c9925f013	1341	} else {
donatien	0:632c9925f013	1342	/* We get here if the incoming segment is out-of-sequence. */
donatien	0:632c9925f013	1343	tcp_send_empty_ack(pcb);
donatien	0:632c9925f013	1344	#if TCP_QUEUE_OOSEQ
donatien	0:632c9925f013	1345	/* We queue the segment on the ->ooseq queue. */
donatien	0:632c9925f013	1346	if (pcb->ooseq == NULL) {
donatien	0:632c9925f013	1347	pcb->ooseq = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1348	} else {
donatien	0:632c9925f013	1349	/* If the queue is not empty, we walk through the queue and
donatien	0:632c9925f013	1350	try to find a place where the sequence number of the
donatien	0:632c9925f013	1351	incoming segment is between the sequence numbers of the
donatien	0:632c9925f013	1352	previous and the next segment on the ->ooseq queue. That is
donatien	0:632c9925f013	1353	the place where we put the incoming segment. If needed, we
donatien	0:632c9925f013	1354	trim the second edges of the previous and the incoming
donatien	0:632c9925f013	1355	segment so that it will fit into the sequence.
donatien	0:632c9925f013	1356
donatien	0:632c9925f013	1357	If the incoming segment has the same sequence number as a
donatien	0:632c9925f013	1358	segment on the ->ooseq queue, we discard the segment that
donatien	0:632c9925f013	1359	contains less data. */
donatien	0:632c9925f013	1360
donatien	0:632c9925f013	1361	prev = NULL;
donatien	0:632c9925f013	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
donatien	0:632c9925f013	1363	if (seqno == next->tcphdr->seqno) {
donatien	0:632c9925f013	1364	/* The sequence number of the incoming segment is the
donatien	0:632c9925f013	1365	same as the sequence number of the segment on
donatien	0:632c9925f013	1366	->ooseq. We check the lengths to see which one to
donatien	0:632c9925f013	1367	discard. */
donatien	0:632c9925f013	1368	if (inseg.len > next->len) {
donatien	0:632c9925f013	1369	/* The incoming segment is larger than the old
donatien	0:632c9925f013	1370	segment. We replace some segments with the new
donatien	0:632c9925f013	1371	one. */
donatien	0:632c9925f013	1372	cseg = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1373	if (cseg != NULL) {
donatien	0:632c9925f013	1374	if (prev != NULL) {
donatien	0:632c9925f013	1375	prev->next = cseg;
donatien	0:632c9925f013	1376	} else {
donatien	0:632c9925f013	1377	pcb->ooseq = cseg;
donatien	0:632c9925f013	1378	}
donatien	0:632c9925f013	1379	tcp_oos_insert_segment(cseg, next);
donatien	0:632c9925f013	1380	}
donatien	0:632c9925f013	1381	break;
donatien	0:632c9925f013	1382	} else {
donatien	0:632c9925f013	1383	/* Either the lenghts are the same or the incoming
donatien	0:632c9925f013	1384	segment was smaller than the old one; in either
donatien	0:632c9925f013	1385	case, we ditch the incoming segment. */
donatien	0:632c9925f013	1386	break;
donatien	0:632c9925f013	1387	}
donatien	0:632c9925f013	1388	} else {
donatien	0:632c9925f013	1389	if (prev == NULL) {
donatien	0:632c9925f013	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
donatien	0:632c9925f013	1391	/* The sequence number of the incoming segment is lower
donatien	0:632c9925f013	1392	than the sequence number of the first segment on the
donatien	0:632c9925f013	1393	queue. We put the incoming segment first on the
donatien	0:632c9925f013	1394	queue. */
donatien	0:632c9925f013	1395	cseg = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1396	if (cseg != NULL) {
donatien	0:632c9925f013	1397	pcb->ooseq = cseg;
donatien	0:632c9925f013	1398	tcp_oos_insert_segment(cseg, next);
donatien	0:632c9925f013	1399	}
donatien	0:632c9925f013	1400	break;
donatien	0:632c9925f013	1401	}
donatien	0:632c9925f013	1402	} else {
donatien	0:632c9925f013	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
donatien	0:632c9925f013	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
donatien	0:632c9925f013	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
donatien	0:632c9925f013	1406	/* The sequence number of the incoming segment is in
donatien	0:632c9925f013	1407	between the sequence numbers of the previous and
donatien	0:632c9925f013	1408	the next segment on ->ooseq. We trim trim the previous
donatien	0:632c9925f013	1409	segment, delete next segments that included in received segment
donatien	0:632c9925f013	1410	and trim received, if needed. */
donatien	0:632c9925f013	1411	cseg = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1412	if (cseg != NULL) {
donatien	0:632c9925f013	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
donatien	0:632c9925f013	1414	/* We need to trim the prev segment. */
donatien	0:632c9925f013	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
donatien	0:632c9925f013	1416	pbuf_realloc(prev->p, prev->len);
donatien	0:632c9925f013	1417	}
donatien	0:632c9925f013	1418	prev->next = cseg;
donatien	0:632c9925f013	1419	tcp_oos_insert_segment(cseg, next);
donatien	0:632c9925f013	1420	}
donatien	0:632c9925f013	1421	break;
donatien	0:632c9925f013	1422	}
donatien	0:632c9925f013	1423	}
donatien	0:632c9925f013	1424	/* If the "next" segment is the last segment on the
donatien	0:632c9925f013	1425	ooseq queue, we add the incoming segment to the end
donatien	0:632c9925f013	1426	of the list. */
donatien	0:632c9925f013	1427	if (next->next == NULL &&
donatien	0:632c9925f013	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
donatien	0:632c9925f013	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
donatien	0:632c9925f013	1430	/* segment "next" already contains all data */
donatien	0:632c9925f013	1431	break;
donatien	0:632c9925f013	1432	}
donatien	0:632c9925f013	1433	next->next = tcp_seg_copy(&inseg);
donatien	0:632c9925f013	1434	if (next->next != NULL) {
donatien	0:632c9925f013	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
donatien	0:632c9925f013	1436	/* We need to trim the last segment. */
donatien	0:632c9925f013	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
donatien	0:632c9925f013	1438	pbuf_realloc(next->p, next->len);
donatien	0:632c9925f013	1439	}
donatien	5:dd63a1e02b1b	1440	/* check if the remote side overruns our receive window */
donatien	5:dd63a1e02b1b	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
donatien	5:dd63a1e02b1b	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
donatien	5:dd63a1e02b1b	1443	("tcp_receive: other end overran receive window"
donatien	5:dd63a1e02b1b	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
donatien	5:dd63a1e02b1b	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
donatien	5:dd63a1e02b1b	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
donatien	5:dd63a1e02b1b	1447	/* Must remove the FIN from the header as we're trimming
donatien	5:dd63a1e02b1b	1448	* that byte of sequence-space from the packet */
donatien	5:dd63a1e02b1b	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
donatien	5:dd63a1e02b1b	1450	}
donatien	5:dd63a1e02b1b	1451	/* Adjust length of segment to fit in the window. */
donatien	5:dd63a1e02b1b	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
donatien	5:dd63a1e02b1b	1453	pbuf_realloc(next->next->p, next->next->len);
donatien	5:dd63a1e02b1b	1454	tcplen = TCP_TCPLEN(next->next);
donatien	5:dd63a1e02b1b	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
donatien	5:dd63a1e02b1b	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
donatien	5:dd63a1e02b1b	1457	}
donatien	0:632c9925f013	1458	}
donatien	0:632c9925f013	1459	break;
donatien	0:632c9925f013	1460	}
donatien	0:632c9925f013	1461	}
donatien	0:632c9925f013	1462	prev = next;
donatien	0:632c9925f013	1463	}
donatien	0:632c9925f013	1464	}
donatien	0:632c9925f013	1465	#endif /* TCP_QUEUE_OOSEQ */
donatien	0:632c9925f013	1466
donatien	0:632c9925f013	1467	}
donatien	0:632c9925f013	1468	} else {
donatien	0:632c9925f013	1469	/* The incoming segment is not withing the window. */
donatien	0:632c9925f013	1470	tcp_send_empty_ack(pcb);
donatien	0:632c9925f013	1471	}
donatien	0:632c9925f013	1472	} else {
donatien	0:632c9925f013	1473	/* Segments with length 0 is taken care of here. Segments that
donatien	0:632c9925f013	1474	fall out of the window are ACKed. */
donatien	0:632c9925f013	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
donatien	0:632c9925f013	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
donatien	0:632c9925f013	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
donatien	0:632c9925f013	1478	tcp_ack_now(pcb);
donatien	0:632c9925f013	1479	}
donatien	0:632c9925f013	1480	}
donatien	0:632c9925f013	1481	}
donatien	0:632c9925f013	1482
donatien	0:632c9925f013	1483	/**
donatien	0:632c9925f013	1484	* Parses the options contained in the incoming segment.
donatien	0:632c9925f013	1485	*
donatien	0:632c9925f013	1486	* Called from tcp_listen_input() and tcp_process().
donatien	0:632c9925f013	1487	* Currently, only the MSS option is supported!
donatien	0:632c9925f013	1488	*
donatien	0:632c9925f013	1489	* @param pcb the tcp_pcb for which a segment arrived
donatien	0:632c9925f013	1490	*/
donatien	0:632c9925f013	1491	static void
donatien	0:632c9925f013	1492	tcp_parseopt(struct tcp_pcb *pcb)
donatien	0:632c9925f013	1493	{
donatien	0:632c9925f013	1494	u16_t c, max_c;
donatien	0:632c9925f013	1495	u16_t mss;
donatien	0:632c9925f013	1496	u8_t *opts, opt;
donatien	0:632c9925f013	1497	#if LWIP_TCP_TIMESTAMPS
donatien	0:632c9925f013	1498	u32_t tsval;
donatien	0:632c9925f013	1499	#endif
donatien	0:632c9925f013	1500
donatien	0:632c9925f013	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
donatien	0:632c9925f013	1502
donatien	0:632c9925f013	1503	/* Parse the TCP MSS option, if present. */
donatien	0:632c9925f013	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
donatien	0:632c9925f013	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
donatien	0:632c9925f013	1506	for (c = 0; c < max_c; ) {
donatien	0:632c9925f013	1507	opt = opts[c];
donatien	0:632c9925f013	1508	switch (opt) {
donatien	0:632c9925f013	1509	case 0x00:
donatien	0:632c9925f013	1510	/* End of options. */
donatien	0:632c9925f013	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
donatien	0:632c9925f013	1512	return;
donatien	0:632c9925f013	1513	case 0x01:
donatien	0:632c9925f013	1514	/* NOP option. */
donatien	0:632c9925f013	1515	++c;
donatien	0:632c9925f013	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
donatien	0:632c9925f013	1517	break;
donatien	0:632c9925f013	1518	case 0x02:
donatien	0:632c9925f013	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
donatien	0:632c9925f013	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
donatien	0:632c9925f013	1521	/* Bad length */
donatien	0:632c9925f013	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
donatien	0:632c9925f013	1523	return;
donatien	0:632c9925f013	1524	}
donatien	0:632c9925f013	1525	/* An MSS option with the right option length. */
donatien	0:632c9925f013	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
donatien	0:632c9925f013	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
donatien	0:632c9925f013	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
donatien	0:632c9925f013	1529	/* Advance to next option */
donatien	0:632c9925f013	1530	c += 0x04;
donatien	0:632c9925f013	1531	break;
donatien	0:632c9925f013	1532	#if LWIP_TCP_TIMESTAMPS
donatien	0:632c9925f013	1533	case 0x08:
donatien	0:632c9925f013	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
donatien	0:632c9925f013	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
donatien	0:632c9925f013	1536	/* Bad length */
donatien	0:632c9925f013	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
donatien	0:632c9925f013	1538	return;
donatien	0:632c9925f013	1539	}
donatien	0:632c9925f013	1540	/* TCP timestamp option with valid length */
donatien	0:632c9925f013	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
donatien	0:632c9925f013	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
donatien	0:632c9925f013	1543	if (flags & TCP_SYN) {
donatien	0:632c9925f013	1544	pcb->ts_recent = ntohl(tsval);
donatien	0:632c9925f013	1545	pcb->flags \|= TF_TIMESTAMP;
donatien	0:632c9925f013	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
donatien	0:632c9925f013	1547	pcb->ts_recent = ntohl(tsval);
donatien	0:632c9925f013	1548	}
donatien	0:632c9925f013	1549	/* Advance to next option */
donatien	0:632c9925f013	1550	c += 0x0A;
donatien	0:632c9925f013	1551	break;
donatien	0:632c9925f013	1552	#endif
donatien	0:632c9925f013	1553	default:
donatien	0:632c9925f013	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
donatien	0:632c9925f013	1555	if (opts[c + 1] == 0) {
donatien	0:632c9925f013	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
donatien	0:632c9925f013	1557	/* If the length field is zero, the options are malformed
donatien	0:632c9925f013	1558	and we don't process them further. */
donatien	0:632c9925f013	1559	return;
donatien	0:632c9925f013	1560	}
donatien	0:632c9925f013	1561	/* All other options have a length field, so that we easily
donatien	0:632c9925f013	1562	can skip past them. */
donatien	0:632c9925f013	1563	c += opts[c + 1];
donatien	0:632c9925f013	1564	}
donatien	0:632c9925f013	1565	}
donatien	0:632c9925f013	1566	}
donatien	0:632c9925f013	1567	}
donatien	0:632c9925f013	1568
donatien	0:632c9925f013	1569	#endif /* LWIP_TCP */

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Type:	Program
Created:	11 Jun 2010
Imports:	2654
Forks:	0
Commits:	12
Dependents:	3
Dependencies:	0
Followers:	13

This repository is Public (Unlisted).

lwip/core/tcp_in.c@11:da4498f591ee, 2010-08-05 (annotated)

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