NetServicesMinHTTPMod - Copy of NetServicesMin with the HTTP Client libra…

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Copy of NetServicesMin with the HTTP Client library. Includes modification for HTTP servers which send the HTTP status line in its own packet.

lwip/core/tcp_in.c@0:18dd877d2c77, 2011-05-26 (annotated)

Committer:: andrewbonney
Date:: Thu May 26 10:02:40 2011 +0000
Revision:: 0:18dd877d2c77

Who changed what in which revision?

User	Revision	Line number	New contents of line
andrewbonney	0:18dd877d2c77	1	/**
andrewbonney	0:18dd877d2c77	2	* @file
andrewbonney	0:18dd877d2c77	3	* Transmission Control Protocol, incoming traffic
andrewbonney	0:18dd877d2c77	4	*
andrewbonney	0:18dd877d2c77	5	* The input processing functions of the TCP layer.
andrewbonney	0:18dd877d2c77	6	*
andrewbonney	0:18dd877d2c77	7	* These functions are generally called in the order (ip_input() ->)
andrewbonney	0:18dd877d2c77	8	* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
andrewbonney	0:18dd877d2c77	9	*
andrewbonney	0:18dd877d2c77	10	*/
andrewbonney	0:18dd877d2c77	11
andrewbonney	0:18dd877d2c77	12	/*
andrewbonney	0:18dd877d2c77	13	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
andrewbonney	0:18dd877d2c77	14	* All rights reserved.
andrewbonney	0:18dd877d2c77	15	*
andrewbonney	0:18dd877d2c77	16	* Redistribution and use in source and binary forms, with or without modification,
andrewbonney	0:18dd877d2c77	17	* are permitted provided that the following conditions are met:
andrewbonney	0:18dd877d2c77	18	*
andrewbonney	0:18dd877d2c77	19	* 1. Redistributions of source code must retain the above copyright notice,
andrewbonney	0:18dd877d2c77	20	* this list of conditions and the following disclaimer.
andrewbonney	0:18dd877d2c77	21	* 2. Redistributions in binary form must reproduce the above copyright notice,
andrewbonney	0:18dd877d2c77	22	* this list of conditions and the following disclaimer in the documentation
andrewbonney	0:18dd877d2c77	23	* and/or other materials provided with the distribution.
andrewbonney	0:18dd877d2c77	24	* 3. The name of the author may not be used to endorse or promote products
andrewbonney	0:18dd877d2c77	25	* derived from this software without specific prior written permission.
andrewbonney	0:18dd877d2c77	26	*
andrewbonney	0:18dd877d2c77	27	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
andrewbonney	0:18dd877d2c77	28	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
andrewbonney	0:18dd877d2c77	29	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
andrewbonney	0:18dd877d2c77	30	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
andrewbonney	0:18dd877d2c77	31	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
andrewbonney	0:18dd877d2c77	32	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
andrewbonney	0:18dd877d2c77	33	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
andrewbonney	0:18dd877d2c77	34	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
andrewbonney	0:18dd877d2c77	35	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
andrewbonney	0:18dd877d2c77	36	* OF SUCH DAMAGE.
andrewbonney	0:18dd877d2c77	37	*
andrewbonney	0:18dd877d2c77	38	* This file is part of the lwIP TCP/IP stack.
andrewbonney	0:18dd877d2c77	39	*
andrewbonney	0:18dd877d2c77	40	* Author: Adam Dunkels <adam@sics.se>
andrewbonney	0:18dd877d2c77	41	*
andrewbonney	0:18dd877d2c77	42	*/
andrewbonney	0:18dd877d2c77	43
andrewbonney	0:18dd877d2c77	44	#include "lwip/opt.h"
andrewbonney	0:18dd877d2c77	45
andrewbonney	0:18dd877d2c77	46	#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
andrewbonney	0:18dd877d2c77	47
andrewbonney	0:18dd877d2c77	48	#include "lwip/tcp_impl.h"
andrewbonney	0:18dd877d2c77	49	#include "lwip/def.h"
andrewbonney	0:18dd877d2c77	50	#include "lwip/ip_addr.h"
andrewbonney	0:18dd877d2c77	51	#include "lwip/netif.h"
andrewbonney	0:18dd877d2c77	52	#include "lwip/mem.h"
andrewbonney	0:18dd877d2c77	53	#include "lwip/memp.h"
andrewbonney	0:18dd877d2c77	54	#include "lwip/inet_chksum.h"
andrewbonney	0:18dd877d2c77	55	#include "lwip/stats.h"
andrewbonney	0:18dd877d2c77	56	#include "lwip/snmp.h"
andrewbonney	0:18dd877d2c77	57	#include "arch/perf.h"
andrewbonney	0:18dd877d2c77	58
andrewbonney	0:18dd877d2c77	59	/* These variables are global to all functions involved in the input
andrewbonney	0:18dd877d2c77	60	processing of TCP segments. They are set by the tcp_input()
andrewbonney	0:18dd877d2c77	61	function. */
andrewbonney	0:18dd877d2c77	62	static struct tcp_seg inseg;
andrewbonney	0:18dd877d2c77	63	static struct tcp_hdr *tcphdr;
andrewbonney	0:18dd877d2c77	64	static struct ip_hdr *iphdr;
andrewbonney	0:18dd877d2c77	65	static u32_t seqno, ackno;
andrewbonney	0:18dd877d2c77	66	static u8_t flags;
andrewbonney	0:18dd877d2c77	67	static u16_t tcplen;
andrewbonney	0:18dd877d2c77	68
andrewbonney	0:18dd877d2c77	69	static u8_t recv_flags;
andrewbonney	0:18dd877d2c77	70	static struct pbuf *recv_data;
andrewbonney	0:18dd877d2c77	71
andrewbonney	0:18dd877d2c77	72	struct tcp_pcb *tcp_input_pcb;
andrewbonney	0:18dd877d2c77	73
andrewbonney	0:18dd877d2c77	74	/* Forward declarations. */
andrewbonney	0:18dd877d2c77	75	static err_t tcp_process(struct tcp_pcb *pcb);
andrewbonney	0:18dd877d2c77	76	static void tcp_receive(struct tcp_pcb *pcb);
andrewbonney	0:18dd877d2c77	77	static void tcp_parseopt(struct tcp_pcb *pcb);
andrewbonney	0:18dd877d2c77	78
andrewbonney	0:18dd877d2c77	79	static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
andrewbonney	0:18dd877d2c77	80	static err_t tcp_timewait_input(struct tcp_pcb *pcb);
andrewbonney	0:18dd877d2c77	81
andrewbonney	0:18dd877d2c77	82	/**
andrewbonney	0:18dd877d2c77	83	* The initial input processing of TCP. It verifies the TCP header, demultiplexes
andrewbonney	0:18dd877d2c77	84	* the segment between the PCBs and passes it on to tcp_process(), which implements
andrewbonney	0:18dd877d2c77	85	* the TCP finite state machine. This function is called by the IP layer (in
andrewbonney	0:18dd877d2c77	86	* ip_input()).
andrewbonney	0:18dd877d2c77	87	*
andrewbonney	0:18dd877d2c77	88	* @param p received TCP segment to process (p->payload pointing to the IP header)
andrewbonney	0:18dd877d2c77	89	* @param inp network interface on which this segment was received
andrewbonney	0:18dd877d2c77	90	*/
andrewbonney	0:18dd877d2c77	91	void
andrewbonney	0:18dd877d2c77	92	tcp_input(struct pbuf p, struct netif inp)
andrewbonney	0:18dd877d2c77	93	{
andrewbonney	0:18dd877d2c77	94	struct tcp_pcb pcb, prev;
andrewbonney	0:18dd877d2c77	95	struct tcp_pcb_listen *lpcb;
andrewbonney	0:18dd877d2c77	96	#if SO_REUSE
andrewbonney	0:18dd877d2c77	97	struct tcp_pcb *lpcb_prev = NULL;
andrewbonney	0:18dd877d2c77	98	struct tcp_pcb_listen *lpcb_any = NULL;
andrewbonney	0:18dd877d2c77	99	#endif /* SO_REUSE */
andrewbonney	0:18dd877d2c77	100	u8_t hdrlen;
andrewbonney	0:18dd877d2c77	101	err_t err;
andrewbonney	0:18dd877d2c77	102
andrewbonney	0:18dd877d2c77	103	PERF_START;
andrewbonney	0:18dd877d2c77	104
andrewbonney	0:18dd877d2c77	105	TCP_STATS_INC(tcp.recv);
andrewbonney	0:18dd877d2c77	106	snmp_inc_tcpinsegs();
andrewbonney	0:18dd877d2c77	107
andrewbonney	0:18dd877d2c77	108	iphdr = (struct ip_hdr *)p->payload;
andrewbonney	0:18dd877d2c77	109	tcphdr = (struct tcp_hdr )((u8_t )p->payload + IPH_HL(iphdr) * 4);
andrewbonney	0:18dd877d2c77	110
andrewbonney	0:18dd877d2c77	111	#if TCP_INPUT_DEBUG
andrewbonney	0:18dd877d2c77	112	tcp_debug_print(tcphdr);
andrewbonney	0:18dd877d2c77	113	#endif
andrewbonney	0:18dd877d2c77	114
andrewbonney	0:18dd877d2c77	115	/* remove header from payload */
andrewbonney	0:18dd877d2c77	116	if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) \|\| (p->tot_len < sizeof(struct tcp_hdr))) {
andrewbonney	0:18dd877d2c77	117	/* drop short packets */
andrewbonney	0:18dd877d2c77	118	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
andrewbonney	0:18dd877d2c77	119	TCP_STATS_INC(tcp.lenerr);
andrewbonney	0:18dd877d2c77	120	TCP_STATS_INC(tcp.drop);
andrewbonney	0:18dd877d2c77	121	snmp_inc_tcpinerrs();
andrewbonney	0:18dd877d2c77	122	pbuf_free(p);
andrewbonney	0:18dd877d2c77	123	return;
andrewbonney	0:18dd877d2c77	124	}
andrewbonney	0:18dd877d2c77	125
andrewbonney	0:18dd877d2c77	126	/* Don't even process incoming broadcasts/multicasts. */
andrewbonney	0:18dd877d2c77	127	if (ip_addr_isbroadcast(&current_iphdr_dest, inp) \|\|
andrewbonney	0:18dd877d2c77	128	ip_addr_ismulticast(&current_iphdr_dest)) {
andrewbonney	0:18dd877d2c77	129	TCP_STATS_INC(tcp.proterr);
andrewbonney	0:18dd877d2c77	130	TCP_STATS_INC(tcp.drop);
andrewbonney	0:18dd877d2c77	131	snmp_inc_tcpinerrs();
andrewbonney	0:18dd877d2c77	132	pbuf_free(p);
andrewbonney	0:18dd877d2c77	133	return;
andrewbonney	0:18dd877d2c77	134	}
andrewbonney	0:18dd877d2c77	135
andrewbonney	0:18dd877d2c77	136	#if CHECKSUM_CHECK_TCP
andrewbonney	0:18dd877d2c77	137	/* Verify TCP checksum. */
andrewbonney	0:18dd877d2c77	138	if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
andrewbonney	0:18dd877d2c77	139	IP_PROTO_TCP, p->tot_len) != 0) {
andrewbonney	0:18dd877d2c77	140	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
andrewbonney	0:18dd877d2c77	141	inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
andrewbonney	0:18dd877d2c77	142	IP_PROTO_TCP, p->tot_len)));
andrewbonney	0:18dd877d2c77	143	#if TCP_DEBUG
andrewbonney	0:18dd877d2c77	144	tcp_debug_print(tcphdr);
andrewbonney	0:18dd877d2c77	145	#endif /* TCP_DEBUG */
andrewbonney	0:18dd877d2c77	146	TCP_STATS_INC(tcp.chkerr);
andrewbonney	0:18dd877d2c77	147	TCP_STATS_INC(tcp.drop);
andrewbonney	0:18dd877d2c77	148	snmp_inc_tcpinerrs();
andrewbonney	0:18dd877d2c77	149	pbuf_free(p);
andrewbonney	0:18dd877d2c77	150	return;
andrewbonney	0:18dd877d2c77	151	}
andrewbonney	0:18dd877d2c77	152	#endif
andrewbonney	0:18dd877d2c77	153
andrewbonney	0:18dd877d2c77	154	/* Move the payload pointer in the pbuf so that it points to the
andrewbonney	0:18dd877d2c77	155	TCP data instead of the TCP header. */
andrewbonney	0:18dd877d2c77	156	hdrlen = TCPH_HDRLEN(tcphdr);
andrewbonney	0:18dd877d2c77	157	if(pbuf_header(p, -(hdrlen * 4))){
andrewbonney	0:18dd877d2c77	158	/* drop short packets */
andrewbonney	0:18dd877d2c77	159	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
andrewbonney	0:18dd877d2c77	160	TCP_STATS_INC(tcp.lenerr);
andrewbonney	0:18dd877d2c77	161	TCP_STATS_INC(tcp.drop);
andrewbonney	0:18dd877d2c77	162	snmp_inc_tcpinerrs();
andrewbonney	0:18dd877d2c77	163	pbuf_free(p);
andrewbonney	0:18dd877d2c77	164	return;
andrewbonney	0:18dd877d2c77	165	}
andrewbonney	0:18dd877d2c77	166
andrewbonney	0:18dd877d2c77	167	/* Convert fields in TCP header to host byte order. */
andrewbonney	0:18dd877d2c77	168	tcphdr->src = ntohs(tcphdr->src);
andrewbonney	0:18dd877d2c77	169	tcphdr->dest = ntohs(tcphdr->dest);
andrewbonney	0:18dd877d2c77	170	seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
andrewbonney	0:18dd877d2c77	171	ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
andrewbonney	0:18dd877d2c77	172	tcphdr->wnd = ntohs(tcphdr->wnd);
andrewbonney	0:18dd877d2c77	173
andrewbonney	0:18dd877d2c77	174	flags = TCPH_FLAGS(tcphdr);
andrewbonney	0:18dd877d2c77	175	tcplen = p->tot_len + ((flags & (TCP_FIN \| TCP_SYN)) ? 1 : 0);
andrewbonney	0:18dd877d2c77	176
andrewbonney	0:18dd877d2c77	177	/* Demultiplex an incoming segment. First, we check if it is destined
andrewbonney	0:18dd877d2c77	178	for an active connection. */
andrewbonney	0:18dd877d2c77	179	prev = NULL;
andrewbonney	0:18dd877d2c77	180
andrewbonney	0:18dd877d2c77	181
andrewbonney	0:18dd877d2c77	182	for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
andrewbonney	0:18dd877d2c77	183	LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
andrewbonney	0:18dd877d2c77	184	LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
andrewbonney	0:18dd877d2c77	185	LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
andrewbonney	0:18dd877d2c77	186	if (pcb->remote_port == tcphdr->src &&
andrewbonney	0:18dd877d2c77	187	pcb->local_port == tcphdr->dest &&
andrewbonney	0:18dd877d2c77	188	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
andrewbonney	0:18dd877d2c77	189	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
andrewbonney	0:18dd877d2c77	190
andrewbonney	0:18dd877d2c77	191	/* Move this PCB to the front of the list so that subsequent
andrewbonney	0:18dd877d2c77	192	lookups will be faster (we exploit locality in TCP segment
andrewbonney	0:18dd877d2c77	193	arrivals). */
andrewbonney	0:18dd877d2c77	194	LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
andrewbonney	0:18dd877d2c77	195	if (prev != NULL) {
andrewbonney	0:18dd877d2c77	196	prev->next = pcb->next;
andrewbonney	0:18dd877d2c77	197	pcb->next = tcp_active_pcbs;
andrewbonney	0:18dd877d2c77	198	tcp_active_pcbs = pcb;
andrewbonney	0:18dd877d2c77	199	}
andrewbonney	0:18dd877d2c77	200	LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
andrewbonney	0:18dd877d2c77	201	break;
andrewbonney	0:18dd877d2c77	202	}
andrewbonney	0:18dd877d2c77	203	prev = pcb;
andrewbonney	0:18dd877d2c77	204	}
andrewbonney	0:18dd877d2c77	205
andrewbonney	0:18dd877d2c77	206	if (pcb == NULL) {
andrewbonney	0:18dd877d2c77	207	/* If it did not go to an active connection, we check the connections
andrewbonney	0:18dd877d2c77	208	in the TIME-WAIT state. */
andrewbonney	0:18dd877d2c77	209	for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
andrewbonney	0:18dd877d2c77	210	LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
andrewbonney	0:18dd877d2c77	211	if (pcb->remote_port == tcphdr->src &&
andrewbonney	0:18dd877d2c77	212	pcb->local_port == tcphdr->dest &&
andrewbonney	0:18dd877d2c77	213	ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
andrewbonney	0:18dd877d2c77	214	ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
andrewbonney	0:18dd877d2c77	215	/* We don't really care enough to move this PCB to the front
andrewbonney	0:18dd877d2c77	216	of the list since we are not very likely to receive that
andrewbonney	0:18dd877d2c77	217	many segments for connections in TIME-WAIT. */
andrewbonney	0:18dd877d2c77	218	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
andrewbonney	0:18dd877d2c77	219	tcp_timewait_input(pcb);
andrewbonney	0:18dd877d2c77	220	pbuf_free(p);
andrewbonney	0:18dd877d2c77	221	return;
andrewbonney	0:18dd877d2c77	222	}
andrewbonney	0:18dd877d2c77	223	}
andrewbonney	0:18dd877d2c77	224
andrewbonney	0:18dd877d2c77	225	/* Finally, if we still did not get a match, we check all PCBs that
andrewbonney	0:18dd877d2c77	226	are LISTENing for incoming connections. */
andrewbonney	0:18dd877d2c77	227	prev = NULL;
andrewbonney	0:18dd877d2c77	228	for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
andrewbonney	0:18dd877d2c77	229	if (lpcb->local_port == tcphdr->dest) {
andrewbonney	0:18dd877d2c77	230	#if SO_REUSE
andrewbonney	0:18dd877d2c77	231	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
andrewbonney	0:18dd877d2c77	232	/* found an exact match */
andrewbonney	0:18dd877d2c77	233	break;
andrewbonney	0:18dd877d2c77	234	} else if(ip_addr_isany(&(lpcb->local_ip))) {
andrewbonney	0:18dd877d2c77	235	/* found an ANY-match */
andrewbonney	0:18dd877d2c77	236	lpcb_any = lpcb;
andrewbonney	0:18dd877d2c77	237	lpcb_prev = prev;
andrewbonney	0:18dd877d2c77	238	}
andrewbonney	0:18dd877d2c77	239	#else /* SO_REUSE */
andrewbonney	0:18dd877d2c77	240	if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) \|\|
andrewbonney	0:18dd877d2c77	241	ip_addr_isany(&(lpcb->local_ip))) {
andrewbonney	0:18dd877d2c77	242	/* found a match */
andrewbonney	0:18dd877d2c77	243	break;
andrewbonney	0:18dd877d2c77	244	}
andrewbonney	0:18dd877d2c77	245	#endif /* SO_REUSE */
andrewbonney	0:18dd877d2c77	246	}
andrewbonney	0:18dd877d2c77	247	prev = (struct tcp_pcb *)lpcb;
andrewbonney	0:18dd877d2c77	248	}
andrewbonney	0:18dd877d2c77	249	#if SO_REUSE
andrewbonney	0:18dd877d2c77	250	/* first try specific local IP */
andrewbonney	0:18dd877d2c77	251	if (lpcb == NULL) {
andrewbonney	0:18dd877d2c77	252	/* only pass to ANY if no specific local IP has been found */
andrewbonney	0:18dd877d2c77	253	lpcb = lpcb_any;
andrewbonney	0:18dd877d2c77	254	prev = lpcb_prev;
andrewbonney	0:18dd877d2c77	255	}
andrewbonney	0:18dd877d2c77	256	#endif /* SO_REUSE */
andrewbonney	0:18dd877d2c77	257	if (lpcb != NULL) {
andrewbonney	0:18dd877d2c77	258	/* Move this PCB to the front of the list so that subsequent
andrewbonney	0:18dd877d2c77	259	lookups will be faster (we exploit locality in TCP segment
andrewbonney	0:18dd877d2c77	260	arrivals). */
andrewbonney	0:18dd877d2c77	261	if (prev != NULL) {
andrewbonney	0:18dd877d2c77	262	((struct tcp_pcb_listen *)prev)->next = lpcb->next;
andrewbonney	0:18dd877d2c77	263	/* our successor is the remainder of the listening list */
andrewbonney	0:18dd877d2c77	264	lpcb->next = tcp_listen_pcbs.listen_pcbs;
andrewbonney	0:18dd877d2c77	265	/* put this listening pcb at the head of the listening list */
andrewbonney	0:18dd877d2c77	266	tcp_listen_pcbs.listen_pcbs = lpcb;
andrewbonney	0:18dd877d2c77	267	}
andrewbonney	0:18dd877d2c77	268
andrewbonney	0:18dd877d2c77	269	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
andrewbonney	0:18dd877d2c77	270	tcp_listen_input(lpcb);
andrewbonney	0:18dd877d2c77	271	pbuf_free(p);
andrewbonney	0:18dd877d2c77	272	return;
andrewbonney	0:18dd877d2c77	273	}
andrewbonney	0:18dd877d2c77	274	}
andrewbonney	0:18dd877d2c77	275
andrewbonney	0:18dd877d2c77	276	#if TCP_INPUT_DEBUG
andrewbonney	0:18dd877d2c77	277	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
andrewbonney	0:18dd877d2c77	278	tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
andrewbonney	0:18dd877d2c77	279	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
andrewbonney	0:18dd877d2c77	280	#endif /* TCP_INPUT_DEBUG */
andrewbonney	0:18dd877d2c77	281
andrewbonney	0:18dd877d2c77	282
andrewbonney	0:18dd877d2c77	283	if (pcb != NULL) {
andrewbonney	0:18dd877d2c77	284	/* The incoming segment belongs to a connection. */
andrewbonney	0:18dd877d2c77	285	#if TCP_INPUT_DEBUG
andrewbonney	0:18dd877d2c77	286	#if TCP_DEBUG
andrewbonney	0:18dd877d2c77	287	tcp_debug_print_state(pcb->state);
andrewbonney	0:18dd877d2c77	288	#endif /* TCP_DEBUG */
andrewbonney	0:18dd877d2c77	289	#endif /* TCP_INPUT_DEBUG */
andrewbonney	0:18dd877d2c77	290
andrewbonney	0:18dd877d2c77	291	/* Set up a tcp_seg structure. */
andrewbonney	0:18dd877d2c77	292	inseg.next = NULL;
andrewbonney	0:18dd877d2c77	293	inseg.len = p->tot_len;
andrewbonney	0:18dd877d2c77	294	inseg.dataptr = p->payload;
andrewbonney	0:18dd877d2c77	295	inseg.p = p;
andrewbonney	0:18dd877d2c77	296	inseg.tcphdr = tcphdr;
andrewbonney	0:18dd877d2c77	297
andrewbonney	0:18dd877d2c77	298	recv_data = NULL;
andrewbonney	0:18dd877d2c77	299	recv_flags = 0;
andrewbonney	0:18dd877d2c77	300
andrewbonney	0:18dd877d2c77	301	/* If there is data which was previously "refused" by upper layer */
andrewbonney	0:18dd877d2c77	302	if (pcb->refused_data != NULL) {
andrewbonney	0:18dd877d2c77	303	/* Notify again application with data previously received. */
andrewbonney	0:18dd877d2c77	304	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
andrewbonney	0:18dd877d2c77	305	TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
andrewbonney	0:18dd877d2c77	306	if (err == ERR_OK) {
andrewbonney	0:18dd877d2c77	307	pcb->refused_data = NULL;
andrewbonney	0:18dd877d2c77	308	} else {
andrewbonney	0:18dd877d2c77	309	/* if err == ERR_ABRT, 'pcb' is already deallocated */
andrewbonney	0:18dd877d2c77	310	/* drop incoming packets, because pcb is "full" */
andrewbonney	0:18dd877d2c77	311	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
andrewbonney	0:18dd877d2c77	312	TCP_STATS_INC(tcp.drop);
andrewbonney	0:18dd877d2c77	313	snmp_inc_tcpinerrs();
andrewbonney	0:18dd877d2c77	314	pbuf_free(p);
andrewbonney	0:18dd877d2c77	315	return;
andrewbonney	0:18dd877d2c77	316	}
andrewbonney	0:18dd877d2c77	317	}
andrewbonney	0:18dd877d2c77	318	tcp_input_pcb = pcb;
andrewbonney	0:18dd877d2c77	319	err = tcp_process(pcb);
andrewbonney	0:18dd877d2c77	320	/* A return value of ERR_ABRT means that tcp_abort() was called
andrewbonney	0:18dd877d2c77	321	and that the pcb has been freed. If so, we don't do anything. */
andrewbonney	0:18dd877d2c77	322	if (err != ERR_ABRT) {
andrewbonney	0:18dd877d2c77	323	if (recv_flags & TF_RESET) {
andrewbonney	0:18dd877d2c77	324	/* TF_RESET means that the connection was reset by the other
andrewbonney	0:18dd877d2c77	325	end. We then call the error callback to inform the
andrewbonney	0:18dd877d2c77	326	application that the connection is dead before we
andrewbonney	0:18dd877d2c77	327	deallocate the PCB. */
andrewbonney	0:18dd877d2c77	328	TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
andrewbonney	0:18dd877d2c77	329	tcp_pcb_remove(&tcp_active_pcbs, pcb);
andrewbonney	0:18dd877d2c77	330	memp_free(MEMP_TCP_PCB, pcb);
andrewbonney	0:18dd877d2c77	331	} else if (recv_flags & TF_CLOSED) {
andrewbonney	0:18dd877d2c77	332	/* The connection has been closed and we will deallocate the
andrewbonney	0:18dd877d2c77	333	PCB. */
andrewbonney	0:18dd877d2c77	334	tcp_pcb_remove(&tcp_active_pcbs, pcb);
andrewbonney	0:18dd877d2c77	335	memp_free(MEMP_TCP_PCB, pcb);
andrewbonney	0:18dd877d2c77	336	} else {
andrewbonney	0:18dd877d2c77	337	err = ERR_OK;
andrewbonney	0:18dd877d2c77	338	/* If the application has registered a "sent" function to be
andrewbonney	0:18dd877d2c77	339	called when new send buffer space is available, we call it
andrewbonney	0:18dd877d2c77	340	now. */
andrewbonney	0:18dd877d2c77	341	if (pcb->acked > 0) {
andrewbonney	0:18dd877d2c77	342	TCP_EVENT_SENT(pcb, pcb->acked, err);
andrewbonney	0:18dd877d2c77	343	if (err == ERR_ABRT) {
andrewbonney	0:18dd877d2c77	344	goto aborted;
andrewbonney	0:18dd877d2c77	345	}
andrewbonney	0:18dd877d2c77	346	}
andrewbonney	0:18dd877d2c77	347
andrewbonney	0:18dd877d2c77	348	if (recv_data != NULL) {
andrewbonney	0:18dd877d2c77	349	if (pcb->flags & TF_RXCLOSED) {
andrewbonney	0:18dd877d2c77	350	/* received data although already closed -> abort (send RST) to
andrewbonney	0:18dd877d2c77	351	notify the remote host that not all data has been processed */
andrewbonney	0:18dd877d2c77	352	pbuf_free(recv_data);
andrewbonney	0:18dd877d2c77	353	tcp_abort(pcb);
andrewbonney	0:18dd877d2c77	354	goto aborted;
andrewbonney	0:18dd877d2c77	355	}
andrewbonney	0:18dd877d2c77	356	if (flags & TCP_PSH) {
andrewbonney	0:18dd877d2c77	357	recv_data->flags \|= PBUF_FLAG_PUSH;
andrewbonney	0:18dd877d2c77	358	}
andrewbonney	0:18dd877d2c77	359
andrewbonney	0:18dd877d2c77	360	/* Notify application that data has been received. */
andrewbonney	0:18dd877d2c77	361	TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
andrewbonney	0:18dd877d2c77	362	if (err == ERR_ABRT) {
andrewbonney	0:18dd877d2c77	363	goto aborted;
andrewbonney	0:18dd877d2c77	364	}
andrewbonney	0:18dd877d2c77	365
andrewbonney	0:18dd877d2c77	366	/* If the upper layer can't receive this data, store it */
andrewbonney	0:18dd877d2c77	367	if (err != ERR_OK) {
andrewbonney	0:18dd877d2c77	368	pcb->refused_data = recv_data;
andrewbonney	0:18dd877d2c77	369	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
andrewbonney	0:18dd877d2c77	370	}
andrewbonney	0:18dd877d2c77	371	}
andrewbonney	0:18dd877d2c77	372
andrewbonney	0:18dd877d2c77	373	/* If a FIN segment was received, we call the callback
andrewbonney	0:18dd877d2c77	374	function with a NULL buffer to indicate EOF. */
andrewbonney	0:18dd877d2c77	375	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:18dd877d2c77	376	/* correct rcv_wnd as the application won't call tcp_recved()
andrewbonney	0:18dd877d2c77	377	for the FIN's seqno */
andrewbonney	0:18dd877d2c77	378	if (pcb->rcv_wnd != TCP_WND) {
andrewbonney	0:18dd877d2c77	379	pcb->rcv_wnd++;
andrewbonney	0:18dd877d2c77	380	}
andrewbonney	0:18dd877d2c77	381	TCP_EVENT_CLOSED(pcb, err);
andrewbonney	0:18dd877d2c77	382	if (err == ERR_ABRT) {
andrewbonney	0:18dd877d2c77	383	goto aborted;
andrewbonney	0:18dd877d2c77	384	}
andrewbonney	0:18dd877d2c77	385	}
andrewbonney	0:18dd877d2c77	386
andrewbonney	0:18dd877d2c77	387	tcp_input_pcb = NULL;
andrewbonney	0:18dd877d2c77	388	/* Try to send something out. */
andrewbonney	0:18dd877d2c77	389	tcp_output(pcb);
andrewbonney	0:18dd877d2c77	390	#if TCP_INPUT_DEBUG
andrewbonney	0:18dd877d2c77	391	#if TCP_DEBUG
andrewbonney	0:18dd877d2c77	392	tcp_debug_print_state(pcb->state);
andrewbonney	0:18dd877d2c77	393	#endif /* TCP_DEBUG */
andrewbonney	0:18dd877d2c77	394	#endif /* TCP_INPUT_DEBUG */
andrewbonney	0:18dd877d2c77	395	}
andrewbonney	0:18dd877d2c77	396	}
andrewbonney	0:18dd877d2c77	397	/* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
andrewbonney	0:18dd877d2c77	398	Below this line, 'pcb' may not be dereferenced! */
andrewbonney	0:18dd877d2c77	399	aborted:
andrewbonney	0:18dd877d2c77	400	tcp_input_pcb = NULL;
andrewbonney	0:18dd877d2c77	401	recv_data = NULL;
andrewbonney	0:18dd877d2c77	402
andrewbonney	0:18dd877d2c77	403	/* give up our reference to inseg.p */
andrewbonney	0:18dd877d2c77	404	if (inseg.p != NULL)
andrewbonney	0:18dd877d2c77	405	{
andrewbonney	0:18dd877d2c77	406	pbuf_free(inseg.p);
andrewbonney	0:18dd877d2c77	407	inseg.p = NULL;
andrewbonney	0:18dd877d2c77	408	}
andrewbonney	0:18dd877d2c77	409	} else {
andrewbonney	0:18dd877d2c77	410
andrewbonney	0:18dd877d2c77	411	/* If no matching PCB was found, send a TCP RST (reset) to the
andrewbonney	0:18dd877d2c77	412	sender. */
andrewbonney	0:18dd877d2c77	413	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
andrewbonney	0:18dd877d2c77	414	if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
andrewbonney	0:18dd877d2c77	415	TCP_STATS_INC(tcp.proterr);
andrewbonney	0:18dd877d2c77	416	TCP_STATS_INC(tcp.drop);
andrewbonney	0:18dd877d2c77	417	tcp_rst(ackno, seqno + tcplen,
andrewbonney	0:18dd877d2c77	418	ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:18dd877d2c77	419	tcphdr->dest, tcphdr->src);
andrewbonney	0:18dd877d2c77	420	}
andrewbonney	0:18dd877d2c77	421	pbuf_free(p);
andrewbonney	0:18dd877d2c77	422	}
andrewbonney	0:18dd877d2c77	423
andrewbonney	0:18dd877d2c77	424	LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
andrewbonney	0:18dd877d2c77	425	PERF_STOP("tcp_input");
andrewbonney	0:18dd877d2c77	426	}
andrewbonney	0:18dd877d2c77	427
andrewbonney	0:18dd877d2c77	428	/**
andrewbonney	0:18dd877d2c77	429	* Called by tcp_input() when a segment arrives for a listening
andrewbonney	0:18dd877d2c77	430	* connection (from tcp_input()).
andrewbonney	0:18dd877d2c77	431	*
andrewbonney	0:18dd877d2c77	432	* @param pcb the tcp_pcb_listen for which a segment arrived
andrewbonney	0:18dd877d2c77	433	* @return ERR_OK if the segment was processed
andrewbonney	0:18dd877d2c77	434	* another err_t on error
andrewbonney	0:18dd877d2c77	435	*
andrewbonney	0:18dd877d2c77	436	* @note the return value is not (yet?) used in tcp_input()
andrewbonney	0:18dd877d2c77	437	* @note the segment which arrived is saved in global variables, therefore only the pcb
andrewbonney	0:18dd877d2c77	438	* involved is passed as a parameter to this function
andrewbonney	0:18dd877d2c77	439	*/
andrewbonney	0:18dd877d2c77	440	static err_t
andrewbonney	0:18dd877d2c77	441	tcp_listen_input(struct tcp_pcb_listen *pcb)
andrewbonney	0:18dd877d2c77	442	{
andrewbonney	0:18dd877d2c77	443	struct tcp_pcb *npcb;
andrewbonney	0:18dd877d2c77	444	err_t rc;
andrewbonney	0:18dd877d2c77	445
andrewbonney	0:18dd877d2c77	446	/* In the LISTEN state, we check for incoming SYN segments,
andrewbonney	0:18dd877d2c77	447	creates a new PCB, and responds with a SYN\|ACK. */
andrewbonney	0:18dd877d2c77	448	if (flags & TCP_ACK) {
andrewbonney	0:18dd877d2c77	449	/* For incoming segments with the ACK flag set, respond with a
andrewbonney	0:18dd877d2c77	450	RST. */
andrewbonney	0:18dd877d2c77	451	LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
andrewbonney	0:18dd877d2c77	452	tcp_rst(ackno + 1, seqno + tcplen,
andrewbonney	0:18dd877d2c77	453	ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:18dd877d2c77	454	tcphdr->dest, tcphdr->src);
andrewbonney	0:18dd877d2c77	455	} else if (flags & TCP_SYN) {
andrewbonney	0:18dd877d2c77	456	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
andrewbonney	0:18dd877d2c77	457	#if TCP_LISTEN_BACKLOG
andrewbonney	0:18dd877d2c77	458	if (pcb->accepts_pending >= pcb->backlog) {
andrewbonney	0:18dd877d2c77	459	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
andrewbonney	0:18dd877d2c77	460	return ERR_ABRT;
andrewbonney	0:18dd877d2c77	461	}
andrewbonney	0:18dd877d2c77	462	#endif /* TCP_LISTEN_BACKLOG */
andrewbonney	0:18dd877d2c77	463	npcb = tcp_alloc(pcb->prio);
andrewbonney	0:18dd877d2c77	464	/* If a new PCB could not be created (probably due to lack of memory),
andrewbonney	0:18dd877d2c77	465	we don't do anything, but rely on the sender will retransmit the
andrewbonney	0:18dd877d2c77	466	SYN at a time when we have more memory available. */
andrewbonney	0:18dd877d2c77	467	if (npcb == NULL) {
andrewbonney	0:18dd877d2c77	468	LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
andrewbonney	0:18dd877d2c77	469	TCP_STATS_INC(tcp.memerr);
andrewbonney	0:18dd877d2c77	470	return ERR_MEM;
andrewbonney	0:18dd877d2c77	471	}
andrewbonney	0:18dd877d2c77	472	#if TCP_LISTEN_BACKLOG
andrewbonney	0:18dd877d2c77	473	pcb->accepts_pending++;
andrewbonney	0:18dd877d2c77	474	#endif /* TCP_LISTEN_BACKLOG */
andrewbonney	0:18dd877d2c77	475	/* Set up the new PCB. */
andrewbonney	0:18dd877d2c77	476	ip_addr_copy(npcb->local_ip, current_iphdr_dest);
andrewbonney	0:18dd877d2c77	477	npcb->local_port = pcb->local_port;
andrewbonney	0:18dd877d2c77	478	ip_addr_copy(npcb->remote_ip, current_iphdr_src);
andrewbonney	0:18dd877d2c77	479	npcb->remote_port = tcphdr->src;
andrewbonney	0:18dd877d2c77	480	npcb->state = SYN_RCVD;
andrewbonney	0:18dd877d2c77	481	npcb->rcv_nxt = seqno + 1;
andrewbonney	0:18dd877d2c77	482	npcb->rcv_ann_right_edge = npcb->rcv_nxt;
andrewbonney	0:18dd877d2c77	483	npcb->snd_wnd = tcphdr->wnd;
andrewbonney	0:18dd877d2c77	484	npcb->ssthresh = npcb->snd_wnd;
andrewbonney	0:18dd877d2c77	485	npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
andrewbonney	0:18dd877d2c77	486	npcb->callback_arg = pcb->callback_arg;
andrewbonney	0:18dd877d2c77	487	#if LWIP_CALLBACK_API
andrewbonney	0:18dd877d2c77	488	npcb->accept = pcb->accept;
andrewbonney	0:18dd877d2c77	489	#endif /* LWIP_CALLBACK_API */
andrewbonney	0:18dd877d2c77	490	/* inherit socket options */
andrewbonney	0:18dd877d2c77	491	npcb->so_options = pcb->so_options & SOF_INHERITED;
andrewbonney	0:18dd877d2c77	492	/* Register the new PCB so that we can begin receiving segments
andrewbonney	0:18dd877d2c77	493	for it. */
andrewbonney	0:18dd877d2c77	494	TCP_REG(&tcp_active_pcbs, npcb);
andrewbonney	0:18dd877d2c77	495
andrewbonney	0:18dd877d2c77	496	/* Parse any options in the SYN. */
andrewbonney	0:18dd877d2c77	497	tcp_parseopt(npcb);
andrewbonney	0:18dd877d2c77	498	#if TCP_CALCULATE_EFF_SEND_MSS
andrewbonney	0:18dd877d2c77	499	npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
andrewbonney	0:18dd877d2c77	500	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
andrewbonney	0:18dd877d2c77	501
andrewbonney	0:18dd877d2c77	502	snmp_inc_tcppassiveopens();
andrewbonney	0:18dd877d2c77	503
andrewbonney	0:18dd877d2c77	504	/* Send a SYN\|ACK together with the MSS option. */
andrewbonney	0:18dd877d2c77	505	rc = tcp_enqueue_flags(npcb, TCP_SYN \| TCP_ACK);
andrewbonney	0:18dd877d2c77	506	if (rc != ERR_OK) {
andrewbonney	0:18dd877d2c77	507	tcp_abandon(npcb, 0);
andrewbonney	0:18dd877d2c77	508	return rc;
andrewbonney	0:18dd877d2c77	509	}
andrewbonney	0:18dd877d2c77	510	return tcp_output(npcb);
andrewbonney	0:18dd877d2c77	511	}
andrewbonney	0:18dd877d2c77	512	return ERR_OK;
andrewbonney	0:18dd877d2c77	513	}
andrewbonney	0:18dd877d2c77	514
andrewbonney	0:18dd877d2c77	515	/**
andrewbonney	0:18dd877d2c77	516	* Called by tcp_input() when a segment arrives for a connection in
andrewbonney	0:18dd877d2c77	517	* TIME_WAIT.
andrewbonney	0:18dd877d2c77	518	*
andrewbonney	0:18dd877d2c77	519	* @param pcb the tcp_pcb for which a segment arrived
andrewbonney	0:18dd877d2c77	520	*
andrewbonney	0:18dd877d2c77	521	* @note the segment which arrived is saved in global variables, therefore only the pcb
andrewbonney	0:18dd877d2c77	522	* involved is passed as a parameter to this function
andrewbonney	0:18dd877d2c77	523	*/
andrewbonney	0:18dd877d2c77	524	static err_t
andrewbonney	0:18dd877d2c77	525	tcp_timewait_input(struct tcp_pcb *pcb)
andrewbonney	0:18dd877d2c77	526	{
andrewbonney	0:18dd877d2c77	527	/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
andrewbonney	0:18dd877d2c77	528	/* RFC 793 3.9 Event Processing - Segment Arrives:
andrewbonney	0:18dd877d2c77	529	* - first check sequence number - we skip that one in TIME_WAIT (always
andrewbonney	0:18dd877d2c77	530	* acceptable since we only send ACKs)
andrewbonney	0:18dd877d2c77	531	* - second check the RST bit (... return) */
andrewbonney	0:18dd877d2c77	532	if (flags & TCP_RST) {
andrewbonney	0:18dd877d2c77	533	return ERR_OK;
andrewbonney	0:18dd877d2c77	534	}
andrewbonney	0:18dd877d2c77	535	/* - fourth, check the SYN bit, */
andrewbonney	0:18dd877d2c77	536	if (flags & TCP_SYN) {
andrewbonney	0:18dd877d2c77	537	/* If an incoming segment is not acceptable, an acknowledgment
andrewbonney	0:18dd877d2c77	538	should be sent in reply */
andrewbonney	0:18dd877d2c77	539	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
andrewbonney	0:18dd877d2c77	540	/* If the SYN is in the window it is an error, send a reset */
andrewbonney	0:18dd877d2c77	541	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:18dd877d2c77	542	tcphdr->dest, tcphdr->src);
andrewbonney	0:18dd877d2c77	543	return ERR_OK;
andrewbonney	0:18dd877d2c77	544	}
andrewbonney	0:18dd877d2c77	545	} else if (flags & TCP_FIN) {
andrewbonney	0:18dd877d2c77	546	/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
andrewbonney	0:18dd877d2c77	547	Restart the 2 MSL time-wait timeout.*/
andrewbonney	0:18dd877d2c77	548	pcb->tmr = tcp_ticks;
andrewbonney	0:18dd877d2c77	549	}
andrewbonney	0:18dd877d2c77	550
andrewbonney	0:18dd877d2c77	551	if ((tcplen > 0)) {
andrewbonney	0:18dd877d2c77	552	/* Acknowledge data, FIN or out-of-window SYN */
andrewbonney	0:18dd877d2c77	553	pcb->flags \|= TF_ACK_NOW;
andrewbonney	0:18dd877d2c77	554	return tcp_output(pcb);
andrewbonney	0:18dd877d2c77	555	}
andrewbonney	0:18dd877d2c77	556	return ERR_OK;
andrewbonney	0:18dd877d2c77	557	}
andrewbonney	0:18dd877d2c77	558
andrewbonney	0:18dd877d2c77	559	/**
andrewbonney	0:18dd877d2c77	560	* Implements the TCP state machine. Called by tcp_input. In some
andrewbonney	0:18dd877d2c77	561	* states tcp_receive() is called to receive data. The tcp_seg
andrewbonney	0:18dd877d2c77	562	* argument will be freed by the caller (tcp_input()) unless the
andrewbonney	0:18dd877d2c77	563	* recv_data pointer in the pcb is set.
andrewbonney	0:18dd877d2c77	564	*
andrewbonney	0:18dd877d2c77	565	* @param pcb the tcp_pcb for which a segment arrived
andrewbonney	0:18dd877d2c77	566	*
andrewbonney	0:18dd877d2c77	567	* @note the segment which arrived is saved in global variables, therefore only the pcb
andrewbonney	0:18dd877d2c77	568	* involved is passed as a parameter to this function
andrewbonney	0:18dd877d2c77	569	*/
andrewbonney	0:18dd877d2c77	570	static err_t
andrewbonney	0:18dd877d2c77	571	tcp_process(struct tcp_pcb *pcb)
andrewbonney	0:18dd877d2c77	572	{
andrewbonney	0:18dd877d2c77	573	struct tcp_seg *rseg;
andrewbonney	0:18dd877d2c77	574	u8_t acceptable = 0;
andrewbonney	0:18dd877d2c77	575	err_t err;
andrewbonney	0:18dd877d2c77	576
andrewbonney	0:18dd877d2c77	577	err = ERR_OK;
andrewbonney	0:18dd877d2c77	578
andrewbonney	0:18dd877d2c77	579	/* Process incoming RST segments. */
andrewbonney	0:18dd877d2c77	580	if (flags & TCP_RST) {
andrewbonney	0:18dd877d2c77	581	/* First, determine if the reset is acceptable. */
andrewbonney	0:18dd877d2c77	582	if (pcb->state == SYN_SENT) {
andrewbonney	0:18dd877d2c77	583	if (ackno == pcb->snd_nxt) {
andrewbonney	0:18dd877d2c77	584	acceptable = 1;
andrewbonney	0:18dd877d2c77	585	}
andrewbonney	0:18dd877d2c77	586	} else {
andrewbonney	0:18dd877d2c77	587	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
andrewbonney	0:18dd877d2c77	588	pcb->rcv_nxt+pcb->rcv_wnd)) {
andrewbonney	0:18dd877d2c77	589	acceptable = 1;
andrewbonney	0:18dd877d2c77	590	}
andrewbonney	0:18dd877d2c77	591	}
andrewbonney	0:18dd877d2c77	592
andrewbonney	0:18dd877d2c77	593	if (acceptable) {
andrewbonney	0:18dd877d2c77	594	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
andrewbonney	0:18dd877d2c77	595	LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
andrewbonney	0:18dd877d2c77	596	recv_flags \|= TF_RESET;
andrewbonney	0:18dd877d2c77	597	pcb->flags &= ~TF_ACK_DELAY;
andrewbonney	0:18dd877d2c77	598	return ERR_RST;
andrewbonney	0:18dd877d2c77	599	} else {
andrewbonney	0:18dd877d2c77	600	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
andrewbonney	0:18dd877d2c77	601	seqno, pcb->rcv_nxt));
andrewbonney	0:18dd877d2c77	602	LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
andrewbonney	0:18dd877d2c77	603	seqno, pcb->rcv_nxt));
andrewbonney	0:18dd877d2c77	604	return ERR_OK;
andrewbonney	0:18dd877d2c77	605	}
andrewbonney	0:18dd877d2c77	606	}
andrewbonney	0:18dd877d2c77	607
andrewbonney	0:18dd877d2c77	608	if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
andrewbonney	0:18dd877d2c77	609	/* Cope with new connection attempt after remote end crashed */
andrewbonney	0:18dd877d2c77	610	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	611	return ERR_OK;
andrewbonney	0:18dd877d2c77	612	}
andrewbonney	0:18dd877d2c77	613
andrewbonney	0:18dd877d2c77	614	if ((pcb->flags & TF_RXCLOSED) == 0) {
andrewbonney	0:18dd877d2c77	615	/* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
andrewbonney	0:18dd877d2c77	616	pcb->tmr = tcp_ticks;
andrewbonney	0:18dd877d2c77	617	}
andrewbonney	0:18dd877d2c77	618	pcb->keep_cnt_sent = 0;
andrewbonney	0:18dd877d2c77	619
andrewbonney	0:18dd877d2c77	620	tcp_parseopt(pcb);
andrewbonney	0:18dd877d2c77	621
andrewbonney	0:18dd877d2c77	622	/* Do different things depending on the TCP state. */
andrewbonney	0:18dd877d2c77	623	switch (pcb->state) {
andrewbonney	0:18dd877d2c77	624	case SYN_SENT:
andrewbonney	0:18dd877d2c77	625	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
andrewbonney	0:18dd877d2c77	626	pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
andrewbonney	0:18dd877d2c77	627	/* received SYN ACK with expected sequence number? */
andrewbonney	0:18dd877d2c77	628	if ((flags & TCP_ACK) && (flags & TCP_SYN)
andrewbonney	0:18dd877d2c77	629	&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
andrewbonney	0:18dd877d2c77	630	pcb->snd_buf++;
andrewbonney	0:18dd877d2c77	631	pcb->rcv_nxt = seqno + 1;
andrewbonney	0:18dd877d2c77	632	pcb->rcv_ann_right_edge = pcb->rcv_nxt;
andrewbonney	0:18dd877d2c77	633	pcb->lastack = ackno;
andrewbonney	0:18dd877d2c77	634	pcb->snd_wnd = tcphdr->wnd;
andrewbonney	0:18dd877d2c77	635	pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
andrewbonney	0:18dd877d2c77	636	pcb->state = ESTABLISHED;
andrewbonney	0:18dd877d2c77	637
andrewbonney	0:18dd877d2c77	638	#if TCP_CALCULATE_EFF_SEND_MSS
andrewbonney	0:18dd877d2c77	639	pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
andrewbonney	0:18dd877d2c77	640	#endif /* TCP_CALCULATE_EFF_SEND_MSS */
andrewbonney	0:18dd877d2c77	641
andrewbonney	0:18dd877d2c77	642	/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
andrewbonney	0:18dd877d2c77	643	* but for the default value of pcb->mss) */
andrewbonney	0:18dd877d2c77	644	pcb->ssthresh = pcb->mss * 10;
andrewbonney	0:18dd877d2c77	645
andrewbonney	0:18dd877d2c77	646	pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
andrewbonney	0:18dd877d2c77	647	LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
andrewbonney	0:18dd877d2c77	648	--pcb->snd_queuelen;
andrewbonney	0:18dd877d2c77	649	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:18dd877d2c77	650	rseg = pcb->unacked;
andrewbonney	0:18dd877d2c77	651	pcb->unacked = rseg->next;
andrewbonney	0:18dd877d2c77	652
andrewbonney	0:18dd877d2c77	653	/* If there's nothing left to acknowledge, stop the retransmit
andrewbonney	0:18dd877d2c77	654	timer, otherwise reset it to start again */
andrewbonney	0:18dd877d2c77	655	if(pcb->unacked == NULL)
andrewbonney	0:18dd877d2c77	656	pcb->rtime = -1;
andrewbonney	0:18dd877d2c77	657	else {
andrewbonney	0:18dd877d2c77	658	pcb->rtime = 0;
andrewbonney	0:18dd877d2c77	659	pcb->nrtx = 0;
andrewbonney	0:18dd877d2c77	660	}
andrewbonney	0:18dd877d2c77	661
andrewbonney	0:18dd877d2c77	662	tcp_seg_free(rseg);
andrewbonney	0:18dd877d2c77	663
andrewbonney	0:18dd877d2c77	664	/* Call the user specified function to call when sucessfully
andrewbonney	0:18dd877d2c77	665	* connected. */
andrewbonney	0:18dd877d2c77	666	TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
andrewbonney	0:18dd877d2c77	667	if (err == ERR_ABRT) {
andrewbonney	0:18dd877d2c77	668	return ERR_ABRT;
andrewbonney	0:18dd877d2c77	669	}
andrewbonney	0:18dd877d2c77	670	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	671	}
andrewbonney	0:18dd877d2c77	672	/* received ACK? possibly a half-open connection */
andrewbonney	0:18dd877d2c77	673	else if (flags & TCP_ACK) {
andrewbonney	0:18dd877d2c77	674	/* send a RST to bring the other side in a non-synchronized state. */
andrewbonney	0:18dd877d2c77	675	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:18dd877d2c77	676	tcphdr->dest, tcphdr->src);
andrewbonney	0:18dd877d2c77	677	}
andrewbonney	0:18dd877d2c77	678	break;
andrewbonney	0:18dd877d2c77	679	case SYN_RCVD:
andrewbonney	0:18dd877d2c77	680	if (flags & TCP_ACK) {
andrewbonney	0:18dd877d2c77	681	/* expected ACK number? */
andrewbonney	0:18dd877d2c77	682	if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
andrewbonney	0:18dd877d2c77	683	u16_t old_cwnd;
andrewbonney	0:18dd877d2c77	684	pcb->state = ESTABLISHED;
andrewbonney	0:18dd877d2c77	685	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:18dd877d2c77	686	#if LWIP_CALLBACK_API
andrewbonney	0:18dd877d2c77	687	LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
andrewbonney	0:18dd877d2c77	688	#endif
andrewbonney	0:18dd877d2c77	689	/* Call the accept function. */
andrewbonney	0:18dd877d2c77	690	TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
andrewbonney	0:18dd877d2c77	691	if (err != ERR_OK) {
andrewbonney	0:18dd877d2c77	692	/* If the accept function returns with an error, we abort
andrewbonney	0:18dd877d2c77	693	* the connection. */
andrewbonney	0:18dd877d2c77	694	/* Already aborted? */
andrewbonney	0:18dd877d2c77	695	if (err != ERR_ABRT) {
andrewbonney	0:18dd877d2c77	696	tcp_abort(pcb);
andrewbonney	0:18dd877d2c77	697	}
andrewbonney	0:18dd877d2c77	698	return ERR_ABRT;
andrewbonney	0:18dd877d2c77	699	}
andrewbonney	0:18dd877d2c77	700	old_cwnd = pcb->cwnd;
andrewbonney	0:18dd877d2c77	701	/* If there was any data contained within this ACK,
andrewbonney	0:18dd877d2c77	702	* we'd better pass it on to the application as well. */
andrewbonney	0:18dd877d2c77	703	tcp_receive(pcb);
andrewbonney	0:18dd877d2c77	704
andrewbonney	0:18dd877d2c77	705	/* Prevent ACK for SYN to generate a sent event */
andrewbonney	0:18dd877d2c77	706	if (pcb->acked != 0) {
andrewbonney	0:18dd877d2c77	707	pcb->acked--;
andrewbonney	0:18dd877d2c77	708	}
andrewbonney	0:18dd877d2c77	709
andrewbonney	0:18dd877d2c77	710	pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
andrewbonney	0:18dd877d2c77	711
andrewbonney	0:18dd877d2c77	712	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:18dd877d2c77	713	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	714	pcb->state = CLOSE_WAIT;
andrewbonney	0:18dd877d2c77	715	}
andrewbonney	0:18dd877d2c77	716	} else {
andrewbonney	0:18dd877d2c77	717	/* incorrect ACK number, send RST */
andrewbonney	0:18dd877d2c77	718	tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
andrewbonney	0:18dd877d2c77	719	tcphdr->dest, tcphdr->src);
andrewbonney	0:18dd877d2c77	720	}
andrewbonney	0:18dd877d2c77	721	} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
andrewbonney	0:18dd877d2c77	722	/* Looks like another copy of the SYN - retransmit our SYN-ACK */
andrewbonney	0:18dd877d2c77	723	tcp_rexmit(pcb);
andrewbonney	0:18dd877d2c77	724	}
andrewbonney	0:18dd877d2c77	725	break;
andrewbonney	0:18dd877d2c77	726	case CLOSE_WAIT:
andrewbonney	0:18dd877d2c77	727	/* FALLTHROUGH */
andrewbonney	0:18dd877d2c77	728	case ESTABLISHED:
andrewbonney	0:18dd877d2c77	729	tcp_receive(pcb);
andrewbonney	0:18dd877d2c77	730	if (recv_flags & TF_GOT_FIN) { /* passive close */
andrewbonney	0:18dd877d2c77	731	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	732	pcb->state = CLOSE_WAIT;
andrewbonney	0:18dd877d2c77	733	}
andrewbonney	0:18dd877d2c77	734	break;
andrewbonney	0:18dd877d2c77	735	case FIN_WAIT_1:
andrewbonney	0:18dd877d2c77	736	tcp_receive(pcb);
andrewbonney	0:18dd877d2c77	737	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:18dd877d2c77	738	if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
andrewbonney	0:18dd877d2c77	739	LWIP_DEBUGF(TCP_DEBUG,
andrewbonney	0:18dd877d2c77	740	("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:18dd877d2c77	741	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	742	tcp_pcb_purge(pcb);
andrewbonney	0:18dd877d2c77	743	TCP_RMV(&tcp_active_pcbs, pcb);
andrewbonney	0:18dd877d2c77	744	pcb->state = TIME_WAIT;
andrewbonney	0:18dd877d2c77	745	TCP_REG(&tcp_tw_pcbs, pcb);
andrewbonney	0:18dd877d2c77	746	} else {
andrewbonney	0:18dd877d2c77	747	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	748	pcb->state = CLOSING;
andrewbonney	0:18dd877d2c77	749	}
andrewbonney	0:18dd877d2c77	750	} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
andrewbonney	0:18dd877d2c77	751	pcb->state = FIN_WAIT_2;
andrewbonney	0:18dd877d2c77	752	}
andrewbonney	0:18dd877d2c77	753	break;
andrewbonney	0:18dd877d2c77	754	case FIN_WAIT_2:
andrewbonney	0:18dd877d2c77	755	tcp_receive(pcb);
andrewbonney	0:18dd877d2c77	756	if (recv_flags & TF_GOT_FIN) {
andrewbonney	0:18dd877d2c77	757	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:18dd877d2c77	758	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	759	tcp_pcb_purge(pcb);
andrewbonney	0:18dd877d2c77	760	TCP_RMV(&tcp_active_pcbs, pcb);
andrewbonney	0:18dd877d2c77	761	pcb->state = TIME_WAIT;
andrewbonney	0:18dd877d2c77	762	TCP_REG(&tcp_tw_pcbs, pcb);
andrewbonney	0:18dd877d2c77	763	}
andrewbonney	0:18dd877d2c77	764	break;
andrewbonney	0:18dd877d2c77	765	case CLOSING:
andrewbonney	0:18dd877d2c77	766	tcp_receive(pcb);
andrewbonney	0:18dd877d2c77	767	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
andrewbonney	0:18dd877d2c77	768	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:18dd877d2c77	769	tcp_pcb_purge(pcb);
andrewbonney	0:18dd877d2c77	770	TCP_RMV(&tcp_active_pcbs, pcb);
andrewbonney	0:18dd877d2c77	771	pcb->state = TIME_WAIT;
andrewbonney	0:18dd877d2c77	772	TCP_REG(&tcp_tw_pcbs, pcb);
andrewbonney	0:18dd877d2c77	773	}
andrewbonney	0:18dd877d2c77	774	break;
andrewbonney	0:18dd877d2c77	775	case LAST_ACK:
andrewbonney	0:18dd877d2c77	776	tcp_receive(pcb);
andrewbonney	0:18dd877d2c77	777	if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
andrewbonney	0:18dd877d2c77	778	LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
andrewbonney	0:18dd877d2c77	779	/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
andrewbonney	0:18dd877d2c77	780	recv_flags \|= TF_CLOSED;
andrewbonney	0:18dd877d2c77	781	}
andrewbonney	0:18dd877d2c77	782	break;
andrewbonney	0:18dd877d2c77	783	default:
andrewbonney	0:18dd877d2c77	784	break;
andrewbonney	0:18dd877d2c77	785	}
andrewbonney	0:18dd877d2c77	786	return ERR_OK;
andrewbonney	0:18dd877d2c77	787	}
andrewbonney	0:18dd877d2c77	788
andrewbonney	0:18dd877d2c77	789	#if TCP_QUEUE_OOSEQ
andrewbonney	0:18dd877d2c77	790	/**
andrewbonney	0:18dd877d2c77	791	* Insert segment into the list (segments covered with new one will be deleted)
andrewbonney	0:18dd877d2c77	792	*
andrewbonney	0:18dd877d2c77	793	* Called from tcp_receive()
andrewbonney	0:18dd877d2c77	794	*/
andrewbonney	0:18dd877d2c77	795	static void
andrewbonney	0:18dd877d2c77	796	tcp_oos_insert_segment(struct tcp_seg cseg, struct tcp_seg next)
andrewbonney	0:18dd877d2c77	797	{
andrewbonney	0:18dd877d2c77	798	struct tcp_seg *old_seg;
andrewbonney	0:18dd877d2c77	799
andrewbonney	0:18dd877d2c77	800	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	801	/* received segment overlaps all following segments */
andrewbonney	0:18dd877d2c77	802	tcp_segs_free(next);
andrewbonney	0:18dd877d2c77	803	next = NULL;
andrewbonney	0:18dd877d2c77	804	}
andrewbonney	0:18dd877d2c77	805	else {
andrewbonney	0:18dd877d2c77	806	/* delete some following segments
andrewbonney	0:18dd877d2c77	807	oos queue may have segments with FIN flag */
andrewbonney	0:18dd877d2c77	808	while (next &&
andrewbonney	0:18dd877d2c77	809	TCP_SEQ_GEQ((seqno + cseg->len),
andrewbonney	0:18dd877d2c77	810	(next->tcphdr->seqno + next->len))) {
andrewbonney	0:18dd877d2c77	811	/* cseg with FIN already processed */
andrewbonney	0:18dd877d2c77	812	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	813	TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
andrewbonney	0:18dd877d2c77	814	}
andrewbonney	0:18dd877d2c77	815	old_seg = next;
andrewbonney	0:18dd877d2c77	816	next = next->next;
andrewbonney	0:18dd877d2c77	817	tcp_seg_free(old_seg);
andrewbonney	0:18dd877d2c77	818	}
andrewbonney	0:18dd877d2c77	819	if (next &&
andrewbonney	0:18dd877d2c77	820	TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
andrewbonney	0:18dd877d2c77	821	/* We need to trim the incoming segment. */
andrewbonney	0:18dd877d2c77	822	cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
andrewbonney	0:18dd877d2c77	823	pbuf_realloc(cseg->p, cseg->len);
andrewbonney	0:18dd877d2c77	824	}
andrewbonney	0:18dd877d2c77	825	}
andrewbonney	0:18dd877d2c77	826	cseg->next = next;
andrewbonney	0:18dd877d2c77	827	}
andrewbonney	0:18dd877d2c77	828	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:18dd877d2c77	829
andrewbonney	0:18dd877d2c77	830	/**
andrewbonney	0:18dd877d2c77	831	* Called by tcp_process. Checks if the given segment is an ACK for outstanding
andrewbonney	0:18dd877d2c77	832	* data, and if so frees the memory of the buffered data. Next, is places the
andrewbonney	0:18dd877d2c77	833	* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
andrewbonney	0:18dd877d2c77	834	* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
andrewbonney	0:18dd877d2c77	835	* i it has been removed from the buffer.
andrewbonney	0:18dd877d2c77	836	*
andrewbonney	0:18dd877d2c77	837	* If the incoming segment constitutes an ACK for a segment that was used for RTT
andrewbonney	0:18dd877d2c77	838	* estimation, the RTT is estimated here as well.
andrewbonney	0:18dd877d2c77	839	*
andrewbonney	0:18dd877d2c77	840	* Called from tcp_process().
andrewbonney	0:18dd877d2c77	841	*/
andrewbonney	0:18dd877d2c77	842	static void
andrewbonney	0:18dd877d2c77	843	tcp_receive(struct tcp_pcb *pcb)
andrewbonney	0:18dd877d2c77	844	{
andrewbonney	0:18dd877d2c77	845	struct tcp_seg *next;
andrewbonney	0:18dd877d2c77	846	#if TCP_QUEUE_OOSEQ
andrewbonney	0:18dd877d2c77	847	struct tcp_seg prev, cseg;
andrewbonney	0:18dd877d2c77	848	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:18dd877d2c77	849	struct pbuf *p;
andrewbonney	0:18dd877d2c77	850	s32_t off;
andrewbonney	0:18dd877d2c77	851	s16_t m;
andrewbonney	0:18dd877d2c77	852	u32_t right_wnd_edge;
andrewbonney	0:18dd877d2c77	853	u16_t new_tot_len;
andrewbonney	0:18dd877d2c77	854	int found_dupack = 0;
andrewbonney	0:18dd877d2c77	855
andrewbonney	0:18dd877d2c77	856	if (flags & TCP_ACK) {
andrewbonney	0:18dd877d2c77	857	right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
andrewbonney	0:18dd877d2c77	858
andrewbonney	0:18dd877d2c77	859	/* Update window. */
andrewbonney	0:18dd877d2c77	860	if (TCP_SEQ_LT(pcb->snd_wl1, seqno) \|\|
andrewbonney	0:18dd877d2c77	861	(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) \|\|
andrewbonney	0:18dd877d2c77	862	(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
andrewbonney	0:18dd877d2c77	863	pcb->snd_wnd = tcphdr->wnd;
andrewbonney	0:18dd877d2c77	864	pcb->snd_wl1 = seqno;
andrewbonney	0:18dd877d2c77	865	pcb->snd_wl2 = ackno;
andrewbonney	0:18dd877d2c77	866	if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
andrewbonney	0:18dd877d2c77	867	pcb->persist_backoff = 0;
andrewbonney	0:18dd877d2c77	868	}
andrewbonney	0:18dd877d2c77	869	LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
andrewbonney	0:18dd877d2c77	870	#if TCP_WND_DEBUG
andrewbonney	0:18dd877d2c77	871	} else {
andrewbonney	0:18dd877d2c77	872	if (pcb->snd_wnd != tcphdr->wnd) {
andrewbonney	0:18dd877d2c77	873	LWIP_DEBUGF(TCP_WND_DEBUG,
andrewbonney	0:18dd877d2c77	874	("tcp_receive: no window update lastack %"U32_F" ackno %"
andrewbonney	0:18dd877d2c77	875	U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
andrewbonney	0:18dd877d2c77	876	pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
andrewbonney	0:18dd877d2c77	877	}
andrewbonney	0:18dd877d2c77	878	#endif /* TCP_WND_DEBUG */
andrewbonney	0:18dd877d2c77	879	}
andrewbonney	0:18dd877d2c77	880
andrewbonney	0:18dd877d2c77	881	/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
andrewbonney	0:18dd877d2c77	882	* duplicate ack if:
andrewbonney	0:18dd877d2c77	883	* 1) It doesn't ACK new data
andrewbonney	0:18dd877d2c77	884	* 2) length of received packet is zero (i.e. no payload)
andrewbonney	0:18dd877d2c77	885	* 3) the advertised window hasn't changed
andrewbonney	0:18dd877d2c77	886	* 4) There is outstanding unacknowledged data (retransmission timer running)
andrewbonney	0:18dd877d2c77	887	* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
andrewbonney	0:18dd877d2c77	888	*
andrewbonney	0:18dd877d2c77	889	* If it passes all five, should process as a dupack:
andrewbonney	0:18dd877d2c77	890	* a) dupacks < 3: do nothing
andrewbonney	0:18dd877d2c77	891	* b) dupacks == 3: fast retransmit
andrewbonney	0:18dd877d2c77	892	* c) dupacks > 3: increase cwnd
andrewbonney	0:18dd877d2c77	893	*
andrewbonney	0:18dd877d2c77	894	* If it only passes 1-3, should reset dupack counter (and add to
andrewbonney	0:18dd877d2c77	895	* stats, which we don't do in lwIP)
andrewbonney	0:18dd877d2c77	896	*
andrewbonney	0:18dd877d2c77	897	* If it only passes 1, should reset dupack counter
andrewbonney	0:18dd877d2c77	898	*
andrewbonney	0:18dd877d2c77	899	*/
andrewbonney	0:18dd877d2c77	900
andrewbonney	0:18dd877d2c77	901	/* Clause 1 */
andrewbonney	0:18dd877d2c77	902	if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
andrewbonney	0:18dd877d2c77	903	pcb->acked = 0;
andrewbonney	0:18dd877d2c77	904	/* Clause 2 */
andrewbonney	0:18dd877d2c77	905	if (tcplen == 0) {
andrewbonney	0:18dd877d2c77	906	/* Clause 3 */
andrewbonney	0:18dd877d2c77	907	if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
andrewbonney	0:18dd877d2c77	908	/* Clause 4 */
andrewbonney	0:18dd877d2c77	909	if (pcb->rtime >= 0) {
andrewbonney	0:18dd877d2c77	910	/* Clause 5 */
andrewbonney	0:18dd877d2c77	911	if (pcb->lastack == ackno) {
andrewbonney	0:18dd877d2c77	912	found_dupack = 1;
andrewbonney	0:18dd877d2c77	913	if (pcb->dupacks + 1 > pcb->dupacks)
andrewbonney	0:18dd877d2c77	914	++pcb->dupacks;
andrewbonney	0:18dd877d2c77	915	if (pcb->dupacks > 3) {
andrewbonney	0:18dd877d2c77	916	/* Inflate the congestion window, but not if it means that
andrewbonney	0:18dd877d2c77	917	the value overflows. */
andrewbonney	0:18dd877d2c77	918	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
andrewbonney	0:18dd877d2c77	919	pcb->cwnd += pcb->mss;
andrewbonney	0:18dd877d2c77	920	}
andrewbonney	0:18dd877d2c77	921	} else if (pcb->dupacks == 3) {
andrewbonney	0:18dd877d2c77	922	/* Do fast retransmit */
andrewbonney	0:18dd877d2c77	923	tcp_rexmit_fast(pcb);
andrewbonney	0:18dd877d2c77	924	}
andrewbonney	0:18dd877d2c77	925	}
andrewbonney	0:18dd877d2c77	926	}
andrewbonney	0:18dd877d2c77	927	}
andrewbonney	0:18dd877d2c77	928	}
andrewbonney	0:18dd877d2c77	929	/* If Clause (1) or more is true, but not a duplicate ack, reset
andrewbonney	0:18dd877d2c77	930	* count of consecutive duplicate acks */
andrewbonney	0:18dd877d2c77	931	if (!found_dupack) {
andrewbonney	0:18dd877d2c77	932	pcb->dupacks = 0;
andrewbonney	0:18dd877d2c77	933	}
andrewbonney	0:18dd877d2c77	934	} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
andrewbonney	0:18dd877d2c77	935	/* We come here when the ACK acknowledges new data. */
andrewbonney	0:18dd877d2c77	936
andrewbonney	0:18dd877d2c77	937	/* Reset the "IN Fast Retransmit" flag, since we are no longer
andrewbonney	0:18dd877d2c77	938	in fast retransmit. Also reset the congestion window to the
andrewbonney	0:18dd877d2c77	939	slow start threshold. */
andrewbonney	0:18dd877d2c77	940	if (pcb->flags & TF_INFR) {
andrewbonney	0:18dd877d2c77	941	pcb->flags &= ~TF_INFR;
andrewbonney	0:18dd877d2c77	942	pcb->cwnd = pcb->ssthresh;
andrewbonney	0:18dd877d2c77	943	}
andrewbonney	0:18dd877d2c77	944
andrewbonney	0:18dd877d2c77	945	/* Reset the number of retransmissions. */
andrewbonney	0:18dd877d2c77	946	pcb->nrtx = 0;
andrewbonney	0:18dd877d2c77	947
andrewbonney	0:18dd877d2c77	948	/* Reset the retransmission time-out. */
andrewbonney	0:18dd877d2c77	949	pcb->rto = (pcb->sa >> 3) + pcb->sv;
andrewbonney	0:18dd877d2c77	950
andrewbonney	0:18dd877d2c77	951	/* Update the send buffer space. Diff between the two can never exceed 64K? */
andrewbonney	0:18dd877d2c77	952	pcb->acked = (u16_t)(ackno - pcb->lastack);
andrewbonney	0:18dd877d2c77	953
andrewbonney	0:18dd877d2c77	954	pcb->snd_buf += pcb->acked;
andrewbonney	0:18dd877d2c77	955
andrewbonney	0:18dd877d2c77	956	/* Reset the fast retransmit variables. */
andrewbonney	0:18dd877d2c77	957	pcb->dupacks = 0;
andrewbonney	0:18dd877d2c77	958	pcb->lastack = ackno;
andrewbonney	0:18dd877d2c77	959
andrewbonney	0:18dd877d2c77	960	/* Update the congestion control variables (cwnd and
andrewbonney	0:18dd877d2c77	961	ssthresh). */
andrewbonney	0:18dd877d2c77	962	if (pcb->state >= ESTABLISHED) {
andrewbonney	0:18dd877d2c77	963	if (pcb->cwnd < pcb->ssthresh) {
andrewbonney	0:18dd877d2c77	964	if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
andrewbonney	0:18dd877d2c77	965	pcb->cwnd += pcb->mss;
andrewbonney	0:18dd877d2c77	966	}
andrewbonney	0:18dd877d2c77	967	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
andrewbonney	0:18dd877d2c77	968	} else {
andrewbonney	0:18dd877d2c77	969	u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
andrewbonney	0:18dd877d2c77	970	if (new_cwnd > pcb->cwnd) {
andrewbonney	0:18dd877d2c77	971	pcb->cwnd = new_cwnd;
andrewbonney	0:18dd877d2c77	972	}
andrewbonney	0:18dd877d2c77	973	LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
andrewbonney	0:18dd877d2c77	974	}
andrewbonney	0:18dd877d2c77	975	}
andrewbonney	0:18dd877d2c77	976	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
andrewbonney	0:18dd877d2c77	977	ackno,
andrewbonney	0:18dd877d2c77	978	pcb->unacked != NULL?
andrewbonney	0:18dd877d2c77	979	ntohl(pcb->unacked->tcphdr->seqno): 0,
andrewbonney	0:18dd877d2c77	980	pcb->unacked != NULL?
andrewbonney	0:18dd877d2c77	981	ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
andrewbonney	0:18dd877d2c77	982
andrewbonney	0:18dd877d2c77	983	/* Remove segment from the unacknowledged list if the incoming
andrewbonney	0:18dd877d2c77	984	ACK acknowlegdes them. */
andrewbonney	0:18dd877d2c77	985	while (pcb->unacked != NULL &&
andrewbonney	0:18dd877d2c77	986	TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
andrewbonney	0:18dd877d2c77	987	TCP_TCPLEN(pcb->unacked), ackno)) {
andrewbonney	0:18dd877d2c77	988	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
andrewbonney	0:18dd877d2c77	989	ntohl(pcb->unacked->tcphdr->seqno),
andrewbonney	0:18dd877d2c77	990	ntohl(pcb->unacked->tcphdr->seqno) +
andrewbonney	0:18dd877d2c77	991	TCP_TCPLEN(pcb->unacked)));
andrewbonney	0:18dd877d2c77	992
andrewbonney	0:18dd877d2c77	993	next = pcb->unacked;
andrewbonney	0:18dd877d2c77	994	pcb->unacked = pcb->unacked->next;
andrewbonney	0:18dd877d2c77	995
andrewbonney	0:18dd877d2c77	996	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
andrewbonney	0:18dd877d2c77	997	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
andrewbonney	0:18dd877d2c77	998	/* Prevent ACK for FIN to generate a sent event */
andrewbonney	0:18dd877d2c77	999	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
andrewbonney	0:18dd877d2c77	1000	pcb->acked--;
andrewbonney	0:18dd877d2c77	1001	}
andrewbonney	0:18dd877d2c77	1002
andrewbonney	0:18dd877d2c77	1003	pcb->snd_queuelen -= pbuf_clen(next->p);
andrewbonney	0:18dd877d2c77	1004	tcp_seg_free(next);
andrewbonney	0:18dd877d2c77	1005
andrewbonney	0:18dd877d2c77	1006	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:18dd877d2c77	1007	if (pcb->snd_queuelen != 0) {
andrewbonney	0:18dd877d2c77	1008	LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL \|\|
andrewbonney	0:18dd877d2c77	1009	pcb->unsent != NULL);
andrewbonney	0:18dd877d2c77	1010	}
andrewbonney	0:18dd877d2c77	1011	}
andrewbonney	0:18dd877d2c77	1012
andrewbonney	0:18dd877d2c77	1013	/* If there's nothing left to acknowledge, stop the retransmit
andrewbonney	0:18dd877d2c77	1014	timer, otherwise reset it to start again */
andrewbonney	0:18dd877d2c77	1015	if(pcb->unacked == NULL)
andrewbonney	0:18dd877d2c77	1016	pcb->rtime = -1;
andrewbonney	0:18dd877d2c77	1017	else
andrewbonney	0:18dd877d2c77	1018	pcb->rtime = 0;
andrewbonney	0:18dd877d2c77	1019
andrewbonney	0:18dd877d2c77	1020	pcb->polltmr = 0;
andrewbonney	0:18dd877d2c77	1021	} else {
andrewbonney	0:18dd877d2c77	1022	/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
andrewbonney	0:18dd877d2c77	1023	pcb->acked = 0;
andrewbonney	0:18dd877d2c77	1024	}
andrewbonney	0:18dd877d2c77	1025
andrewbonney	0:18dd877d2c77	1026	/* We go through the ->unsent list to see if any of the segments
andrewbonney	0:18dd877d2c77	1027	on the list are acknowledged by the ACK. This may seem
andrewbonney	0:18dd877d2c77	1028	strange since an "unsent" segment shouldn't be acked. The
andrewbonney	0:18dd877d2c77	1029	rationale is that lwIP puts all outstanding segments on the
andrewbonney	0:18dd877d2c77	1030	->unsent list after a retransmission, so these segments may
andrewbonney	0:18dd877d2c77	1031	in fact have been sent once. */
andrewbonney	0:18dd877d2c77	1032	while (pcb->unsent != NULL &&
andrewbonney	0:18dd877d2c77	1033	TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
andrewbonney	0:18dd877d2c77	1034	TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
andrewbonney	0:18dd877d2c77	1035	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
andrewbonney	0:18dd877d2c77	1036	ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
andrewbonney	0:18dd877d2c77	1037	TCP_TCPLEN(pcb->unsent)));
andrewbonney	0:18dd877d2c77	1038
andrewbonney	0:18dd877d2c77	1039	next = pcb->unsent;
andrewbonney	0:18dd877d2c77	1040	pcb->unsent = pcb->unsent->next;
andrewbonney	0:18dd877d2c77	1041	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
andrewbonney	0:18dd877d2c77	1042	LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
andrewbonney	0:18dd877d2c77	1043	/* Prevent ACK for FIN to generate a sent event */
andrewbonney	0:18dd877d2c77	1044	if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
andrewbonney	0:18dd877d2c77	1045	pcb->acked--;
andrewbonney	0:18dd877d2c77	1046	}
andrewbonney	0:18dd877d2c77	1047	pcb->snd_queuelen -= pbuf_clen(next->p);
andrewbonney	0:18dd877d2c77	1048	tcp_seg_free(next);
andrewbonney	0:18dd877d2c77	1049	LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
andrewbonney	0:18dd877d2c77	1050	if (pcb->snd_queuelen != 0) {
andrewbonney	0:18dd877d2c77	1051	LWIP_ASSERT("tcp_receive: valid queue length",
andrewbonney	0:18dd877d2c77	1052	pcb->unacked != NULL \|\| pcb->unsent != NULL);
andrewbonney	0:18dd877d2c77	1053	}
andrewbonney	0:18dd877d2c77	1054	}
andrewbonney	0:18dd877d2c77	1055	/* End of ACK for new data processing. */
andrewbonney	0:18dd877d2c77	1056
andrewbonney	0:18dd877d2c77	1057	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
andrewbonney	0:18dd877d2c77	1058	pcb->rttest, pcb->rtseq, ackno));
andrewbonney	0:18dd877d2c77	1059
andrewbonney	0:18dd877d2c77	1060	/* RTT estimation calculations. This is done by checking if the
andrewbonney	0:18dd877d2c77	1061	incoming segment acknowledges the segment we use to take a
andrewbonney	0:18dd877d2c77	1062	round-trip time measurement. */
andrewbonney	0:18dd877d2c77	1063	if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
andrewbonney	0:18dd877d2c77	1064	/* diff between this shouldn't exceed 32K since this are tcp timer ticks
andrewbonney	0:18dd877d2c77	1065	and a round-trip shouldn't be that long... */
andrewbonney	0:18dd877d2c77	1066	m = (s16_t)(tcp_ticks - pcb->rttest);
andrewbonney	0:18dd877d2c77	1067
andrewbonney	0:18dd877d2c77	1068	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
andrewbonney	0:18dd877d2c77	1069	m, m * TCP_SLOW_INTERVAL));
andrewbonney	0:18dd877d2c77	1070
andrewbonney	0:18dd877d2c77	1071	/* This is taken directly from VJs original code in his paper */
andrewbonney	0:18dd877d2c77	1072	m = m - (pcb->sa >> 3);
andrewbonney	0:18dd877d2c77	1073	pcb->sa += m;
andrewbonney	0:18dd877d2c77	1074	if (m < 0) {
andrewbonney	0:18dd877d2c77	1075	m = -m;
andrewbonney	0:18dd877d2c77	1076	}
andrewbonney	0:18dd877d2c77	1077	m = m - (pcb->sv >> 2);
andrewbonney	0:18dd877d2c77	1078	pcb->sv += m;
andrewbonney	0:18dd877d2c77	1079	pcb->rto = (pcb->sa >> 3) + pcb->sv;
andrewbonney	0:18dd877d2c77	1080
andrewbonney	0:18dd877d2c77	1081	LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
andrewbonney	0:18dd877d2c77	1082	pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
andrewbonney	0:18dd877d2c77	1083
andrewbonney	0:18dd877d2c77	1084	pcb->rttest = 0;
andrewbonney	0:18dd877d2c77	1085	}
andrewbonney	0:18dd877d2c77	1086	}
andrewbonney	0:18dd877d2c77	1087
andrewbonney	0:18dd877d2c77	1088	/* If the incoming segment contains data, we must process it
andrewbonney	0:18dd877d2c77	1089	further. */
andrewbonney	0:18dd877d2c77	1090	if (tcplen > 0) {
andrewbonney	0:18dd877d2c77	1091	/* This code basically does three things:
andrewbonney	0:18dd877d2c77	1092
andrewbonney	0:18dd877d2c77	1093	+) If the incoming segment contains data that is the next
andrewbonney	0:18dd877d2c77	1094	in-sequence data, this data is passed to the application. This
andrewbonney	0:18dd877d2c77	1095	might involve trimming the first edge of the data. The rcv_nxt
andrewbonney	0:18dd877d2c77	1096	variable and the advertised window are adjusted.
andrewbonney	0:18dd877d2c77	1097
andrewbonney	0:18dd877d2c77	1098	+) If the incoming segment has data that is above the next
andrewbonney	0:18dd877d2c77	1099	sequence number expected (->rcv_nxt), the segment is placed on
andrewbonney	0:18dd877d2c77	1100	the ->ooseq queue. This is done by finding the appropriate
andrewbonney	0:18dd877d2c77	1101	place in the ->ooseq queue (which is ordered by sequence
andrewbonney	0:18dd877d2c77	1102	number) and trim the segment in both ends if needed. An
andrewbonney	0:18dd877d2c77	1103	immediate ACK is sent to indicate that we received an
andrewbonney	0:18dd877d2c77	1104	out-of-sequence segment.
andrewbonney	0:18dd877d2c77	1105
andrewbonney	0:18dd877d2c77	1106	+) Finally, we check if the first segment on the ->ooseq queue
andrewbonney	0:18dd877d2c77	1107	now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
andrewbonney	0:18dd877d2c77	1108	rcv_nxt > ooseq->seqno, we must trim the first edge of the
andrewbonney	0:18dd877d2c77	1109	segment on ->ooseq before we adjust rcv_nxt. The data in the
andrewbonney	0:18dd877d2c77	1110	segments that are now on sequence are chained onto the
andrewbonney	0:18dd877d2c77	1111	incoming segment so that we only need to call the application
andrewbonney	0:18dd877d2c77	1112	once.
andrewbonney	0:18dd877d2c77	1113	*/
andrewbonney	0:18dd877d2c77	1114
andrewbonney	0:18dd877d2c77	1115	/* First, we check if we must trim the first edge. We have to do
andrewbonney	0:18dd877d2c77	1116	this if the sequence number of the incoming segment is less
andrewbonney	0:18dd877d2c77	1117	than rcv_nxt, and the sequence number plus the length of the
andrewbonney	0:18dd877d2c77	1118	segment is larger than rcv_nxt. */
andrewbonney	0:18dd877d2c77	1119	/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
andrewbonney	0:18dd877d2c77	1120	if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
andrewbonney	0:18dd877d2c77	1121	if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
andrewbonney	0:18dd877d2c77	1122	/* Trimming the first edge is done by pushing the payload
andrewbonney	0:18dd877d2c77	1123	pointer in the pbuf downwards. This is somewhat tricky since
andrewbonney	0:18dd877d2c77	1124	we do not want to discard the full contents of the pbuf up to
andrewbonney	0:18dd877d2c77	1125	the new starting point of the data since we have to keep the
andrewbonney	0:18dd877d2c77	1126	TCP header which is present in the first pbuf in the chain.
andrewbonney	0:18dd877d2c77	1127
andrewbonney	0:18dd877d2c77	1128	What is done is really quite a nasty hack: the first pbuf in
andrewbonney	0:18dd877d2c77	1129	the pbuf chain is pointed to by inseg.p. Since we need to be
andrewbonney	0:18dd877d2c77	1130	able to deallocate the whole pbuf, we cannot change this
andrewbonney	0:18dd877d2c77	1131	inseg.p pointer to point to any of the later pbufs in the
andrewbonney	0:18dd877d2c77	1132	chain. Instead, we point the ->payload pointer in the first
andrewbonney	0:18dd877d2c77	1133	pbuf to data in one of the later pbufs. We also set the
andrewbonney	0:18dd877d2c77	1134	inseg.data pointer to point to the right place. This way, the
andrewbonney	0:18dd877d2c77	1135	->p pointer will still point to the first pbuf, but the
andrewbonney	0:18dd877d2c77	1136	->p->payload pointer will point to data in another pbuf.
andrewbonney	0:18dd877d2c77	1137
andrewbonney	0:18dd877d2c77	1138	After we are done with adjusting the pbuf pointers we must
andrewbonney	0:18dd877d2c77	1139	adjust the ->data pointer in the seg and the segment
andrewbonney	0:18dd877d2c77	1140	length.*/
andrewbonney	0:18dd877d2c77	1141
andrewbonney	0:18dd877d2c77	1142	off = pcb->rcv_nxt - seqno;
andrewbonney	0:18dd877d2c77	1143	p = inseg.p;
andrewbonney	0:18dd877d2c77	1144	LWIP_ASSERT("inseg.p != NULL", inseg.p);
andrewbonney	0:18dd877d2c77	1145	LWIP_ASSERT("insane offset!", (off < 0x7fff));
andrewbonney	0:18dd877d2c77	1146	if (inseg.p->len < off) {
andrewbonney	0:18dd877d2c77	1147	LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
andrewbonney	0:18dd877d2c77	1148	new_tot_len = (u16_t)(inseg.p->tot_len - off);
andrewbonney	0:18dd877d2c77	1149	while (p->len < off) {
andrewbonney	0:18dd877d2c77	1150	off -= p->len;
andrewbonney	0:18dd877d2c77	1151	/* KJM following line changed (with addition of new_tot_len var)
andrewbonney	0:18dd877d2c77	1152	to fix bug #9076
andrewbonney	0:18dd877d2c77	1153	inseg.p->tot_len -= p->len; */
andrewbonney	0:18dd877d2c77	1154	p->tot_len = new_tot_len;
andrewbonney	0:18dd877d2c77	1155	p->len = 0;
andrewbonney	0:18dd877d2c77	1156	p = p->next;
andrewbonney	0:18dd877d2c77	1157	}
andrewbonney	0:18dd877d2c77	1158	if(pbuf_header(p, (s16_t)-off)) {
andrewbonney	0:18dd877d2c77	1159	/* Do we need to cope with this failing? Assert for now */
andrewbonney	0:18dd877d2c77	1160	LWIP_ASSERT("pbuf_header failed", 0);
andrewbonney	0:18dd877d2c77	1161	}
andrewbonney	0:18dd877d2c77	1162	} else {
andrewbonney	0:18dd877d2c77	1163	if(pbuf_header(inseg.p, (s16_t)-off)) {
andrewbonney	0:18dd877d2c77	1164	/* Do we need to cope with this failing? Assert for now */
andrewbonney	0:18dd877d2c77	1165	LWIP_ASSERT("pbuf_header failed", 0);
andrewbonney	0:18dd877d2c77	1166	}
andrewbonney	0:18dd877d2c77	1167	}
andrewbonney	0:18dd877d2c77	1168	/* KJM following line changed to use p->payload rather than inseg->p->payload
andrewbonney	0:18dd877d2c77	1169	to fix bug #9076 */
andrewbonney	0:18dd877d2c77	1170	inseg.dataptr = p->payload;
andrewbonney	0:18dd877d2c77	1171	inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
andrewbonney	0:18dd877d2c77	1172	inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
andrewbonney	0:18dd877d2c77	1173	}
andrewbonney	0:18dd877d2c77	1174	else {
andrewbonney	0:18dd877d2c77	1175	if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
andrewbonney	0:18dd877d2c77	1176	/* the whole segment is < rcv_nxt */
andrewbonney	0:18dd877d2c77	1177	/* must be a duplicate of a packet that has already been correctly handled */
andrewbonney	0:18dd877d2c77	1178
andrewbonney	0:18dd877d2c77	1179	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
andrewbonney	0:18dd877d2c77	1180	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	1181	}
andrewbonney	0:18dd877d2c77	1182	}
andrewbonney	0:18dd877d2c77	1183
andrewbonney	0:18dd877d2c77	1184	/* The sequence number must be within the window (above rcv_nxt
andrewbonney	0:18dd877d2c77	1185	and below rcv_nxt + rcv_wnd) in order to be further
andrewbonney	0:18dd877d2c77	1186	processed. */
andrewbonney	0:18dd877d2c77	1187	if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
andrewbonney	0:18dd877d2c77	1188	pcb->rcv_nxt + pcb->rcv_wnd - 1)){
andrewbonney	0:18dd877d2c77	1189	if (pcb->rcv_nxt == seqno) {
andrewbonney	0:18dd877d2c77	1190	/* The incoming segment is the next in sequence. We check if
andrewbonney	0:18dd877d2c77	1191	we have to trim the end of the segment and update rcv_nxt
andrewbonney	0:18dd877d2c77	1192	and pass the data to the application. */
andrewbonney	0:18dd877d2c77	1193	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:18dd877d2c77	1194
andrewbonney	0:18dd877d2c77	1195	if (tcplen > pcb->rcv_wnd) {
andrewbonney	0:18dd877d2c77	1196	LWIP_DEBUGF(TCP_INPUT_DEBUG,
andrewbonney	0:18dd877d2c77	1197	("tcp_receive: other end overran receive window"
andrewbonney	0:18dd877d2c77	1198	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
andrewbonney	0:18dd877d2c77	1199	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:18dd877d2c77	1200	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	1201	/* Must remove the FIN from the header as we're trimming
andrewbonney	0:18dd877d2c77	1202	* that byte of sequence-space from the packet */
andrewbonney	0:18dd877d2c77	1203	TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
andrewbonney	0:18dd877d2c77	1204	}
andrewbonney	0:18dd877d2c77	1205	/* Adjust length of segment to fit in the window. */
andrewbonney	0:18dd877d2c77	1206	inseg.len = pcb->rcv_wnd;
andrewbonney	0:18dd877d2c77	1207	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
andrewbonney	0:18dd877d2c77	1208	inseg.len -= 1;
andrewbonney	0:18dd877d2c77	1209	}
andrewbonney	0:18dd877d2c77	1210	pbuf_realloc(inseg.p, inseg.len);
andrewbonney	0:18dd877d2c77	1211	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:18dd877d2c77	1212	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
andrewbonney	0:18dd877d2c77	1213	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:18dd877d2c77	1214	}
andrewbonney	0:18dd877d2c77	1215	#if TCP_QUEUE_OOSEQ
andrewbonney	0:18dd877d2c77	1216	/* Received in-sequence data, adjust ooseq data if:
andrewbonney	0:18dd877d2c77	1217	- FIN has been received or
andrewbonney	0:18dd877d2c77	1218	- inseq overlaps with ooseq */
andrewbonney	0:18dd877d2c77	1219	if (pcb->ooseq != NULL) {
andrewbonney	0:18dd877d2c77	1220	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	1221	LWIP_DEBUGF(TCP_INPUT_DEBUG,
andrewbonney	0:18dd877d2c77	1222	("tcp_receive: received in-order FIN, binning ooseq queue\n"));
andrewbonney	0:18dd877d2c77	1223	/* Received in-order FIN means anything that was received
andrewbonney	0:18dd877d2c77	1224	* out of order must now have been received in-order, so
andrewbonney	0:18dd877d2c77	1225	* bin the ooseq queue */
andrewbonney	0:18dd877d2c77	1226	while (pcb->ooseq != NULL) {
andrewbonney	0:18dd877d2c77	1227	struct tcp_seg *old_ooseq = pcb->ooseq;
andrewbonney	0:18dd877d2c77	1228	pcb->ooseq = pcb->ooseq->next;
andrewbonney	0:18dd877d2c77	1229	tcp_seg_free(old_ooseq);
andrewbonney	0:18dd877d2c77	1230	}
andrewbonney	0:18dd877d2c77	1231	}
andrewbonney	0:18dd877d2c77	1232	else {
andrewbonney	0:18dd877d2c77	1233	next = pcb->ooseq;
andrewbonney	0:18dd877d2c77	1234	/* Remove all segments on ooseq that are covered by inseg already.
andrewbonney	0:18dd877d2c77	1235	* FIN is copied from ooseq to inseg if present. */
andrewbonney	0:18dd877d2c77	1236	while (next &&
andrewbonney	0:18dd877d2c77	1237	TCP_SEQ_GEQ(seqno + tcplen,
andrewbonney	0:18dd877d2c77	1238	next->tcphdr->seqno + next->len)) {
andrewbonney	0:18dd877d2c77	1239	/* inseg cannot have FIN here (already processed above) */
andrewbonney	0:18dd877d2c77	1240	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
andrewbonney	0:18dd877d2c77	1241	(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
andrewbonney	0:18dd877d2c77	1242	TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
andrewbonney	0:18dd877d2c77	1243	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:18dd877d2c77	1244	}
andrewbonney	0:18dd877d2c77	1245	prev = next;
andrewbonney	0:18dd877d2c77	1246	next = next->next;
andrewbonney	0:18dd877d2c77	1247	tcp_seg_free(prev);
andrewbonney	0:18dd877d2c77	1248	}
andrewbonney	0:18dd877d2c77	1249	/* Now trim right side of inseg if it overlaps with the first
andrewbonney	0:18dd877d2c77	1250	* segment on ooseq */
andrewbonney	0:18dd877d2c77	1251	if (next &&
andrewbonney	0:18dd877d2c77	1252	TCP_SEQ_GT(seqno + tcplen,
andrewbonney	0:18dd877d2c77	1253	next->tcphdr->seqno)) {
andrewbonney	0:18dd877d2c77	1254	/* inseg cannot have FIN here (already processed above) */
andrewbonney	0:18dd877d2c77	1255	inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
andrewbonney	0:18dd877d2c77	1256	if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
andrewbonney	0:18dd877d2c77	1257	inseg.len -= 1;
andrewbonney	0:18dd877d2c77	1258	}
andrewbonney	0:18dd877d2c77	1259	pbuf_realloc(inseg.p, inseg.len);
andrewbonney	0:18dd877d2c77	1260	tcplen = TCP_TCPLEN(&inseg);
andrewbonney	0:18dd877d2c77	1261	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
andrewbonney	0:18dd877d2c77	1262	(seqno + tcplen) == next->tcphdr->seqno);
andrewbonney	0:18dd877d2c77	1263	}
andrewbonney	0:18dd877d2c77	1264	pcb->ooseq = next;
andrewbonney	0:18dd877d2c77	1265	}
andrewbonney	0:18dd877d2c77	1266	}
andrewbonney	0:18dd877d2c77	1267	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:18dd877d2c77	1268
andrewbonney	0:18dd877d2c77	1269	pcb->rcv_nxt = seqno + tcplen;
andrewbonney	0:18dd877d2c77	1270
andrewbonney	0:18dd877d2c77	1271	/* Update the receiver's (our) window. */
andrewbonney	0:18dd877d2c77	1272	LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
andrewbonney	0:18dd877d2c77	1273	pcb->rcv_wnd -= tcplen;
andrewbonney	0:18dd877d2c77	1274
andrewbonney	0:18dd877d2c77	1275	tcp_update_rcv_ann_wnd(pcb);
andrewbonney	0:18dd877d2c77	1276
andrewbonney	0:18dd877d2c77	1277	/* If there is data in the segment, we make preparations to
andrewbonney	0:18dd877d2c77	1278	pass this up to the application. The ->recv_data variable
andrewbonney	0:18dd877d2c77	1279	is used for holding the pbuf that goes to the
andrewbonney	0:18dd877d2c77	1280	application. The code for reassembling out-of-sequence data
andrewbonney	0:18dd877d2c77	1281	chains its data on this pbuf as well.
andrewbonney	0:18dd877d2c77	1282
andrewbonney	0:18dd877d2c77	1283	If the segment was a FIN, we set the TF_GOT_FIN flag that will
andrewbonney	0:18dd877d2c77	1284	be used to indicate to the application that the remote side has
andrewbonney	0:18dd877d2c77	1285	closed its end of the connection. */
andrewbonney	0:18dd877d2c77	1286	if (inseg.p->tot_len > 0) {
andrewbonney	0:18dd877d2c77	1287	recv_data = inseg.p;
andrewbonney	0:18dd877d2c77	1288	/* Since this pbuf now is the responsibility of the
andrewbonney	0:18dd877d2c77	1289	application, we delete our reference to it so that we won't
andrewbonney	0:18dd877d2c77	1290	(mistakingly) deallocate it. */
andrewbonney	0:18dd877d2c77	1291	inseg.p = NULL;
andrewbonney	0:18dd877d2c77	1292	}
andrewbonney	0:18dd877d2c77	1293	if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	1294	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
andrewbonney	0:18dd877d2c77	1295	recv_flags \|= TF_GOT_FIN;
andrewbonney	0:18dd877d2c77	1296	}
andrewbonney	0:18dd877d2c77	1297
andrewbonney	0:18dd877d2c77	1298	#if TCP_QUEUE_OOSEQ
andrewbonney	0:18dd877d2c77	1299	/* We now check if we have segments on the ->ooseq queue that
andrewbonney	0:18dd877d2c77	1300	are now in sequence. */
andrewbonney	0:18dd877d2c77	1301	while (pcb->ooseq != NULL &&
andrewbonney	0:18dd877d2c77	1302	pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
andrewbonney	0:18dd877d2c77	1303
andrewbonney	0:18dd877d2c77	1304	cseg = pcb->ooseq;
andrewbonney	0:18dd877d2c77	1305	seqno = pcb->ooseq->tcphdr->seqno;
andrewbonney	0:18dd877d2c77	1306
andrewbonney	0:18dd877d2c77	1307	pcb->rcv_nxt += TCP_TCPLEN(cseg);
andrewbonney	0:18dd877d2c77	1308	LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
andrewbonney	0:18dd877d2c77	1309	pcb->rcv_wnd >= TCP_TCPLEN(cseg));
andrewbonney	0:18dd877d2c77	1310	pcb->rcv_wnd -= TCP_TCPLEN(cseg);
andrewbonney	0:18dd877d2c77	1311
andrewbonney	0:18dd877d2c77	1312	tcp_update_rcv_ann_wnd(pcb);
andrewbonney	0:18dd877d2c77	1313
andrewbonney	0:18dd877d2c77	1314	if (cseg->p->tot_len > 0) {
andrewbonney	0:18dd877d2c77	1315	/* Chain this pbuf onto the pbuf that we will pass to
andrewbonney	0:18dd877d2c77	1316	the application. */
andrewbonney	0:18dd877d2c77	1317	if (recv_data) {
andrewbonney	0:18dd877d2c77	1318	pbuf_cat(recv_data, cseg->p);
andrewbonney	0:18dd877d2c77	1319	} else {
andrewbonney	0:18dd877d2c77	1320	recv_data = cseg->p;
andrewbonney	0:18dd877d2c77	1321	}
andrewbonney	0:18dd877d2c77	1322	cseg->p = NULL;
andrewbonney	0:18dd877d2c77	1323	}
andrewbonney	0:18dd877d2c77	1324	if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	1325	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
andrewbonney	0:18dd877d2c77	1326	recv_flags \|= TF_GOT_FIN;
andrewbonney	0:18dd877d2c77	1327	if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
andrewbonney	0:18dd877d2c77	1328	pcb->state = CLOSE_WAIT;
andrewbonney	0:18dd877d2c77	1329	}
andrewbonney	0:18dd877d2c77	1330	}
andrewbonney	0:18dd877d2c77	1331
andrewbonney	0:18dd877d2c77	1332	pcb->ooseq = cseg->next;
andrewbonney	0:18dd877d2c77	1333	tcp_seg_free(cseg);
andrewbonney	0:18dd877d2c77	1334	}
andrewbonney	0:18dd877d2c77	1335	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:18dd877d2c77	1336
andrewbonney	0:18dd877d2c77	1337
andrewbonney	0:18dd877d2c77	1338	/* Acknowledge the segment(s). */
andrewbonney	0:18dd877d2c77	1339	tcp_ack(pcb);
andrewbonney	0:18dd877d2c77	1340
andrewbonney	0:18dd877d2c77	1341	} else {
andrewbonney	0:18dd877d2c77	1342	/* We get here if the incoming segment is out-of-sequence. */
andrewbonney	0:18dd877d2c77	1343	tcp_send_empty_ack(pcb);
andrewbonney	0:18dd877d2c77	1344	#if TCP_QUEUE_OOSEQ
andrewbonney	0:18dd877d2c77	1345	/* We queue the segment on the ->ooseq queue. */
andrewbonney	0:18dd877d2c77	1346	if (pcb->ooseq == NULL) {
andrewbonney	0:18dd877d2c77	1347	pcb->ooseq = tcp_seg_copy(&inseg);
andrewbonney	0:18dd877d2c77	1348	} else {
andrewbonney	0:18dd877d2c77	1349	/* If the queue is not empty, we walk through the queue and
andrewbonney	0:18dd877d2c77	1350	try to find a place where the sequence number of the
andrewbonney	0:18dd877d2c77	1351	incoming segment is between the sequence numbers of the
andrewbonney	0:18dd877d2c77	1352	previous and the next segment on the ->ooseq queue. That is
andrewbonney	0:18dd877d2c77	1353	the place where we put the incoming segment. If needed, we
andrewbonney	0:18dd877d2c77	1354	trim the second edges of the previous and the incoming
andrewbonney	0:18dd877d2c77	1355	segment so that it will fit into the sequence.
andrewbonney	0:18dd877d2c77	1356
andrewbonney	0:18dd877d2c77	1357	If the incoming segment has the same sequence number as a
andrewbonney	0:18dd877d2c77	1358	segment on the ->ooseq queue, we discard the segment that
andrewbonney	0:18dd877d2c77	1359	contains less data. */
andrewbonney	0:18dd877d2c77	1360
andrewbonney	0:18dd877d2c77	1361	prev = NULL;
andrewbonney	0:18dd877d2c77	1362	for(next = pcb->ooseq; next != NULL; next = next->next) {
andrewbonney	0:18dd877d2c77	1363	if (seqno == next->tcphdr->seqno) {
andrewbonney	0:18dd877d2c77	1364	/* The sequence number of the incoming segment is the
andrewbonney	0:18dd877d2c77	1365	same as the sequence number of the segment on
andrewbonney	0:18dd877d2c77	1366	->ooseq. We check the lengths to see which one to
andrewbonney	0:18dd877d2c77	1367	discard. */
andrewbonney	0:18dd877d2c77	1368	if (inseg.len > next->len) {
andrewbonney	0:18dd877d2c77	1369	/* The incoming segment is larger than the old
andrewbonney	0:18dd877d2c77	1370	segment. We replace some segments with the new
andrewbonney	0:18dd877d2c77	1371	one. */
andrewbonney	0:18dd877d2c77	1372	cseg = tcp_seg_copy(&inseg);
andrewbonney	0:18dd877d2c77	1373	if (cseg != NULL) {
andrewbonney	0:18dd877d2c77	1374	if (prev != NULL) {
andrewbonney	0:18dd877d2c77	1375	prev->next = cseg;
andrewbonney	0:18dd877d2c77	1376	} else {
andrewbonney	0:18dd877d2c77	1377	pcb->ooseq = cseg;
andrewbonney	0:18dd877d2c77	1378	}
andrewbonney	0:18dd877d2c77	1379	tcp_oos_insert_segment(cseg, next);
andrewbonney	0:18dd877d2c77	1380	}
andrewbonney	0:18dd877d2c77	1381	break;
andrewbonney	0:18dd877d2c77	1382	} else {
andrewbonney	0:18dd877d2c77	1383	/* Either the lenghts are the same or the incoming
andrewbonney	0:18dd877d2c77	1384	segment was smaller than the old one; in either
andrewbonney	0:18dd877d2c77	1385	case, we ditch the incoming segment. */
andrewbonney	0:18dd877d2c77	1386	break;
andrewbonney	0:18dd877d2c77	1387	}
andrewbonney	0:18dd877d2c77	1388	} else {
andrewbonney	0:18dd877d2c77	1389	if (prev == NULL) {
andrewbonney	0:18dd877d2c77	1390	if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
andrewbonney	0:18dd877d2c77	1391	/* The sequence number of the incoming segment is lower
andrewbonney	0:18dd877d2c77	1392	than the sequence number of the first segment on the
andrewbonney	0:18dd877d2c77	1393	queue. We put the incoming segment first on the
andrewbonney	0:18dd877d2c77	1394	queue. */
andrewbonney	0:18dd877d2c77	1395	cseg = tcp_seg_copy(&inseg);
andrewbonney	0:18dd877d2c77	1396	if (cseg != NULL) {
andrewbonney	0:18dd877d2c77	1397	pcb->ooseq = cseg;
andrewbonney	0:18dd877d2c77	1398	tcp_oos_insert_segment(cseg, next);
andrewbonney	0:18dd877d2c77	1399	}
andrewbonney	0:18dd877d2c77	1400	break;
andrewbonney	0:18dd877d2c77	1401	}
andrewbonney	0:18dd877d2c77	1402	} else {
andrewbonney	0:18dd877d2c77	1403	/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
andrewbonney	0:18dd877d2c77	1404	TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
andrewbonney	0:18dd877d2c77	1405	if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
andrewbonney	0:18dd877d2c77	1406	/* The sequence number of the incoming segment is in
andrewbonney	0:18dd877d2c77	1407	between the sequence numbers of the previous and
andrewbonney	0:18dd877d2c77	1408	the next segment on ->ooseq. We trim trim the previous
andrewbonney	0:18dd877d2c77	1409	segment, delete next segments that included in received segment
andrewbonney	0:18dd877d2c77	1410	and trim received, if needed. */
andrewbonney	0:18dd877d2c77	1411	cseg = tcp_seg_copy(&inseg);
andrewbonney	0:18dd877d2c77	1412	if (cseg != NULL) {
andrewbonney	0:18dd877d2c77	1413	if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
andrewbonney	0:18dd877d2c77	1414	/* We need to trim the prev segment. */
andrewbonney	0:18dd877d2c77	1415	prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
andrewbonney	0:18dd877d2c77	1416	pbuf_realloc(prev->p, prev->len);
andrewbonney	0:18dd877d2c77	1417	}
andrewbonney	0:18dd877d2c77	1418	prev->next = cseg;
andrewbonney	0:18dd877d2c77	1419	tcp_oos_insert_segment(cseg, next);
andrewbonney	0:18dd877d2c77	1420	}
andrewbonney	0:18dd877d2c77	1421	break;
andrewbonney	0:18dd877d2c77	1422	}
andrewbonney	0:18dd877d2c77	1423	}
andrewbonney	0:18dd877d2c77	1424	/* If the "next" segment is the last segment on the
andrewbonney	0:18dd877d2c77	1425	ooseq queue, we add the incoming segment to the end
andrewbonney	0:18dd877d2c77	1426	of the list. */
andrewbonney	0:18dd877d2c77	1427	if (next->next == NULL &&
andrewbonney	0:18dd877d2c77	1428	TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
andrewbonney	0:18dd877d2c77	1429	if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	1430	/* segment "next" already contains all data */
andrewbonney	0:18dd877d2c77	1431	break;
andrewbonney	0:18dd877d2c77	1432	}
andrewbonney	0:18dd877d2c77	1433	next->next = tcp_seg_copy(&inseg);
andrewbonney	0:18dd877d2c77	1434	if (next->next != NULL) {
andrewbonney	0:18dd877d2c77	1435	if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
andrewbonney	0:18dd877d2c77	1436	/* We need to trim the last segment. */
andrewbonney	0:18dd877d2c77	1437	next->len = (u16_t)(seqno - next->tcphdr->seqno);
andrewbonney	0:18dd877d2c77	1438	pbuf_realloc(next->p, next->len);
andrewbonney	0:18dd877d2c77	1439	}
andrewbonney	0:18dd877d2c77	1440	/* check if the remote side overruns our receive window */
andrewbonney	0:18dd877d2c77	1441	if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
andrewbonney	0:18dd877d2c77	1442	LWIP_DEBUGF(TCP_INPUT_DEBUG,
andrewbonney	0:18dd877d2c77	1443	("tcp_receive: other end overran receive window"
andrewbonney	0:18dd877d2c77	1444	"seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
andrewbonney	0:18dd877d2c77	1445	seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:18dd877d2c77	1446	if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
andrewbonney	0:18dd877d2c77	1447	/* Must remove the FIN from the header as we're trimming
andrewbonney	0:18dd877d2c77	1448	* that byte of sequence-space from the packet */
andrewbonney	0:18dd877d2c77	1449	TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
andrewbonney	0:18dd877d2c77	1450	}
andrewbonney	0:18dd877d2c77	1451	/* Adjust length of segment to fit in the window. */
andrewbonney	0:18dd877d2c77	1452	next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
andrewbonney	0:18dd877d2c77	1453	pbuf_realloc(next->next->p, next->next->len);
andrewbonney	0:18dd877d2c77	1454	tcplen = TCP_TCPLEN(next->next);
andrewbonney	0:18dd877d2c77	1455	LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
andrewbonney	0:18dd877d2c77	1456	(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
andrewbonney	0:18dd877d2c77	1457	}
andrewbonney	0:18dd877d2c77	1458	}
andrewbonney	0:18dd877d2c77	1459	break;
andrewbonney	0:18dd877d2c77	1460	}
andrewbonney	0:18dd877d2c77	1461	}
andrewbonney	0:18dd877d2c77	1462	prev = next;
andrewbonney	0:18dd877d2c77	1463	}
andrewbonney	0:18dd877d2c77	1464	}
andrewbonney	0:18dd877d2c77	1465	#endif /* TCP_QUEUE_OOSEQ */
andrewbonney	0:18dd877d2c77	1466
andrewbonney	0:18dd877d2c77	1467	}
andrewbonney	0:18dd877d2c77	1468	} else {
andrewbonney	0:18dd877d2c77	1469	/* The incoming segment is not withing the window. */
andrewbonney	0:18dd877d2c77	1470	tcp_send_empty_ack(pcb);
andrewbonney	0:18dd877d2c77	1471	}
andrewbonney	0:18dd877d2c77	1472	} else {
andrewbonney	0:18dd877d2c77	1473	/* Segments with length 0 is taken care of here. Segments that
andrewbonney	0:18dd877d2c77	1474	fall out of the window are ACKed. */
andrewbonney	0:18dd877d2c77	1475	/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) \|\|
andrewbonney	0:18dd877d2c77	1476	TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
andrewbonney	0:18dd877d2c77	1477	if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
andrewbonney	0:18dd877d2c77	1478	tcp_ack_now(pcb);
andrewbonney	0:18dd877d2c77	1479	}
andrewbonney	0:18dd877d2c77	1480	}
andrewbonney	0:18dd877d2c77	1481	}
andrewbonney	0:18dd877d2c77	1482
andrewbonney	0:18dd877d2c77	1483	/**
andrewbonney	0:18dd877d2c77	1484	* Parses the options contained in the incoming segment.
andrewbonney	0:18dd877d2c77	1485	*
andrewbonney	0:18dd877d2c77	1486	* Called from tcp_listen_input() and tcp_process().
andrewbonney	0:18dd877d2c77	1487	* Currently, only the MSS option is supported!
andrewbonney	0:18dd877d2c77	1488	*
andrewbonney	0:18dd877d2c77	1489	* @param pcb the tcp_pcb for which a segment arrived
andrewbonney	0:18dd877d2c77	1490	*/
andrewbonney	0:18dd877d2c77	1491	static void
andrewbonney	0:18dd877d2c77	1492	tcp_parseopt(struct tcp_pcb *pcb)
andrewbonney	0:18dd877d2c77	1493	{
andrewbonney	0:18dd877d2c77	1494	u16_t c, max_c;
andrewbonney	0:18dd877d2c77	1495	u16_t mss;
andrewbonney	0:18dd877d2c77	1496	u8_t *opts, opt;
andrewbonney	0:18dd877d2c77	1497	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:18dd877d2c77	1498	u32_t tsval;
andrewbonney	0:18dd877d2c77	1499	#endif
andrewbonney	0:18dd877d2c77	1500
andrewbonney	0:18dd877d2c77	1501	opts = (u8_t *)tcphdr + TCP_HLEN;
andrewbonney	0:18dd877d2c77	1502
andrewbonney	0:18dd877d2c77	1503	/* Parse the TCP MSS option, if present. */
andrewbonney	0:18dd877d2c77	1504	if(TCPH_HDRLEN(tcphdr) > 0x5) {
andrewbonney	0:18dd877d2c77	1505	max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
andrewbonney	0:18dd877d2c77	1506	for (c = 0; c < max_c; ) {
andrewbonney	0:18dd877d2c77	1507	opt = opts[c];
andrewbonney	0:18dd877d2c77	1508	switch (opt) {
andrewbonney	0:18dd877d2c77	1509	case 0x00:
andrewbonney	0:18dd877d2c77	1510	/* End of options. */
andrewbonney	0:18dd877d2c77	1511	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
andrewbonney	0:18dd877d2c77	1512	return;
andrewbonney	0:18dd877d2c77	1513	case 0x01:
andrewbonney	0:18dd877d2c77	1514	/* NOP option. */
andrewbonney	0:18dd877d2c77	1515	++c;
andrewbonney	0:18dd877d2c77	1516	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
andrewbonney	0:18dd877d2c77	1517	break;
andrewbonney	0:18dd877d2c77	1518	case 0x02:
andrewbonney	0:18dd877d2c77	1519	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
andrewbonney	0:18dd877d2c77	1520	if (opts[c + 1] != 0x04 \|\| c + 0x04 > max_c) {
andrewbonney	0:18dd877d2c77	1521	/* Bad length */
andrewbonney	0:18dd877d2c77	1522	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
andrewbonney	0:18dd877d2c77	1523	return;
andrewbonney	0:18dd877d2c77	1524	}
andrewbonney	0:18dd877d2c77	1525	/* An MSS option with the right option length. */
andrewbonney	0:18dd877d2c77	1526	mss = (opts[c + 2] << 8) \| opts[c + 3];
andrewbonney	0:18dd877d2c77	1527	/* Limit the mss to the configured TCP_MSS and prevent division by zero */
andrewbonney	0:18dd877d2c77	1528	pcb->mss = ((mss > TCP_MSS) \|\| (mss == 0)) ? TCP_MSS : mss;
andrewbonney	0:18dd877d2c77	1529	/* Advance to next option */
andrewbonney	0:18dd877d2c77	1530	c += 0x04;
andrewbonney	0:18dd877d2c77	1531	break;
andrewbonney	0:18dd877d2c77	1532	#if LWIP_TCP_TIMESTAMPS
andrewbonney	0:18dd877d2c77	1533	case 0x08:
andrewbonney	0:18dd877d2c77	1534	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
andrewbonney	0:18dd877d2c77	1535	if (opts[c + 1] != 0x0A \|\| c + 0x0A > max_c) {
andrewbonney	0:18dd877d2c77	1536	/* Bad length */
andrewbonney	0:18dd877d2c77	1537	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
andrewbonney	0:18dd877d2c77	1538	return;
andrewbonney	0:18dd877d2c77	1539	}
andrewbonney	0:18dd877d2c77	1540	/* TCP timestamp option with valid length */
andrewbonney	0:18dd877d2c77	1541	tsval = (opts[c+2]) \| (opts[c+3] << 8) \|
andrewbonney	0:18dd877d2c77	1542	(opts[c+4] << 16) \| (opts[c+5] << 24);
andrewbonney	0:18dd877d2c77	1543	if (flags & TCP_SYN) {
andrewbonney	0:18dd877d2c77	1544	pcb->ts_recent = ntohl(tsval);
andrewbonney	0:18dd877d2c77	1545	pcb->flags \|= TF_TIMESTAMP;
andrewbonney	0:18dd877d2c77	1546	} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
andrewbonney	0:18dd877d2c77	1547	pcb->ts_recent = ntohl(tsval);
andrewbonney	0:18dd877d2c77	1548	}
andrewbonney	0:18dd877d2c77	1549	/* Advance to next option */
andrewbonney	0:18dd877d2c77	1550	c += 0x0A;
andrewbonney	0:18dd877d2c77	1551	break;
andrewbonney	0:18dd877d2c77	1552	#endif
andrewbonney	0:18dd877d2c77	1553	default:
andrewbonney	0:18dd877d2c77	1554	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
andrewbonney	0:18dd877d2c77	1555	if (opts[c + 1] == 0) {
andrewbonney	0:18dd877d2c77	1556	LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
andrewbonney	0:18dd877d2c77	1557	/* If the length field is zero, the options are malformed
andrewbonney	0:18dd877d2c77	1558	and we don't process them further. */
andrewbonney	0:18dd877d2c77	1559	return;
andrewbonney	0:18dd877d2c77	1560	}
andrewbonney	0:18dd877d2c77	1561	/* All other options have a length field, so that we easily
andrewbonney	0:18dd877d2c77	1562	can skip past them. */
andrewbonney	0:18dd877d2c77	1563	c += opts[c + 1];
andrewbonney	0:18dd877d2c77	1564	}
andrewbonney	0:18dd877d2c77	1565	}
andrewbonney	0:18dd877d2c77	1566	}
andrewbonney	0:18dd877d2c77	1567	}
andrewbonney	0:18dd877d2c77	1568
andrewbonney	0:18dd877d2c77	1569	#endif /* LWIP_TCP */

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Type:	Library
Created:	26 May 2011
Imports:	33
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

lwip/core/tcp_in.c@0:18dd877d2c77, 2011-05-26 (annotated)

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