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Dependencies:   EthernetInterface SDFileSystem mbed-rtos mbed

EthernetInterface/lwip/core/tcp_in.c@1:6465a3f5c58a, 2018-03-06 (annotated)

Committer:
sunyiming
Date:
Tue Mar 06 08:53:46 2018 +0000
Revision:
1:6465a3f5c58a
??OK

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sunyiming 1:6465a3f5c58a 1 /**
sunyiming 1:6465a3f5c58a 2 * @file
sunyiming 1:6465a3f5c58a 3 * Transmission Control Protocol, incoming traffic
sunyiming 1:6465a3f5c58a 4 *
sunyiming 1:6465a3f5c58a 5 * The input processing functions of the TCP layer.
sunyiming 1:6465a3f5c58a 6 *
sunyiming 1:6465a3f5c58a 7 * These functions are generally called in the order (ip_input() ->)
sunyiming 1:6465a3f5c58a 8 * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
sunyiming 1:6465a3f5c58a 9 *
sunyiming 1:6465a3f5c58a 10 */
sunyiming 1:6465a3f5c58a 11
sunyiming 1:6465a3f5c58a 12 /*
sunyiming 1:6465a3f5c58a 13 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
sunyiming 1:6465a3f5c58a 14 * All rights reserved.
sunyiming 1:6465a3f5c58a 15 *
sunyiming 1:6465a3f5c58a 16 * Redistribution and use in source and binary forms, with or without modification,
sunyiming 1:6465a3f5c58a 17 * are permitted provided that the following conditions are met:
sunyiming 1:6465a3f5c58a 18 *
sunyiming 1:6465a3f5c58a 19 * 1. Redistributions of source code must retain the above copyright notice,
sunyiming 1:6465a3f5c58a 20 * this list of conditions and the following disclaimer.
sunyiming 1:6465a3f5c58a 21 * 2. Redistributions in binary form must reproduce the above copyright notice,
sunyiming 1:6465a3f5c58a 22 * this list of conditions and the following disclaimer in the documentation
sunyiming 1:6465a3f5c58a 23 * and/or other materials provided with the distribution.
sunyiming 1:6465a3f5c58a 24 * 3. The name of the author may not be used to endorse or promote products
sunyiming 1:6465a3f5c58a 25 * derived from this software without specific prior written permission.
sunyiming 1:6465a3f5c58a 26 *
sunyiming 1:6465a3f5c58a 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
sunyiming 1:6465a3f5c58a 28 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
sunyiming 1:6465a3f5c58a 29 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
sunyiming 1:6465a3f5c58a 30 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
sunyiming 1:6465a3f5c58a 31 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
sunyiming 1:6465a3f5c58a 32 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
sunyiming 1:6465a3f5c58a 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
sunyiming 1:6465a3f5c58a 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
sunyiming 1:6465a3f5c58a 35 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
sunyiming 1:6465a3f5c58a 36 * OF SUCH DAMAGE.
sunyiming 1:6465a3f5c58a 37 *
sunyiming 1:6465a3f5c58a 38 * This file is part of the lwIP TCP/IP stack.
sunyiming 1:6465a3f5c58a 39 *
sunyiming 1:6465a3f5c58a 40 * Author: Adam Dunkels <adam@sics.se>
sunyiming 1:6465a3f5c58a 41 *
sunyiming 1:6465a3f5c58a 42 */
sunyiming 1:6465a3f5c58a 43
sunyiming 1:6465a3f5c58a 44 #include "lwip/opt.h"
sunyiming 1:6465a3f5c58a 45
sunyiming 1:6465a3f5c58a 46 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
sunyiming 1:6465a3f5c58a 47
sunyiming 1:6465a3f5c58a 48 #include "lwip/tcp_impl.h"
sunyiming 1:6465a3f5c58a 49 #include "lwip/def.h"
sunyiming 1:6465a3f5c58a 50 #include "lwip/ip_addr.h"
sunyiming 1:6465a3f5c58a 51 #include "lwip/netif.h"
sunyiming 1:6465a3f5c58a 52 #include "lwip/mem.h"
sunyiming 1:6465a3f5c58a 53 #include "lwip/memp.h"
sunyiming 1:6465a3f5c58a 54 #include "lwip/inet_chksum.h"
sunyiming 1:6465a3f5c58a 55 #include "lwip/stats.h"
sunyiming 1:6465a3f5c58a 56 #include "lwip/snmp.h"
sunyiming 1:6465a3f5c58a 57 #include "arch/perf.h"
sunyiming 1:6465a3f5c58a 58
sunyiming 1:6465a3f5c58a 59 /* These variables are global to all functions involved in the input
sunyiming 1:6465a3f5c58a 60 processing of TCP segments. They are set by the tcp_input()
sunyiming 1:6465a3f5c58a 61 function. */
sunyiming 1:6465a3f5c58a 62 static struct tcp_seg inseg;
sunyiming 1:6465a3f5c58a 63 static struct tcp_hdr *tcphdr;
sunyiming 1:6465a3f5c58a 64 static struct ip_hdr *iphdr;
sunyiming 1:6465a3f5c58a 65 static u32_t seqno, ackno;
sunyiming 1:6465a3f5c58a 66 static u8_t flags;
sunyiming 1:6465a3f5c58a 67 static u16_t tcplen;
sunyiming 1:6465a3f5c58a 68
sunyiming 1:6465a3f5c58a 69 static u8_t recv_flags;
sunyiming 1:6465a3f5c58a 70 static struct pbuf *recv_data;
sunyiming 1:6465a3f5c58a 71
sunyiming 1:6465a3f5c58a 72 struct tcp_pcb *tcp_input_pcb;
sunyiming 1:6465a3f5c58a 73
sunyiming 1:6465a3f5c58a 74 /* Forward declarations. */
sunyiming 1:6465a3f5c58a 75 static err_t tcp_process(struct tcp_pcb *pcb);
sunyiming 1:6465a3f5c58a 76 static void tcp_receive(struct tcp_pcb *pcb);
sunyiming 1:6465a3f5c58a 77 static void tcp_parseopt(struct tcp_pcb *pcb);
sunyiming 1:6465a3f5c58a 78
sunyiming 1:6465a3f5c58a 79 static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
sunyiming 1:6465a3f5c58a 80 static err_t tcp_timewait_input(struct tcp_pcb *pcb);
sunyiming 1:6465a3f5c58a 81
sunyiming 1:6465a3f5c58a 82 /**
sunyiming 1:6465a3f5c58a 83 * The initial input processing of TCP. It verifies the TCP header, demultiplexes
sunyiming 1:6465a3f5c58a 84 * the segment between the PCBs and passes it on to tcp_process(), which implements
sunyiming 1:6465a3f5c58a 85 * the TCP finite state machine. This function is called by the IP layer (in
sunyiming 1:6465a3f5c58a 86 * ip_input()).
sunyiming 1:6465a3f5c58a 87 *
sunyiming 1:6465a3f5c58a 88 * @param p received TCP segment to process (p->payload pointing to the IP header)
sunyiming 1:6465a3f5c58a 89 * @param inp network interface on which this segment was received
sunyiming 1:6465a3f5c58a 90 */
sunyiming 1:6465a3f5c58a 91 void
sunyiming 1:6465a3f5c58a 92 tcp_input(struct pbuf *p, struct netif *inp)
sunyiming 1:6465a3f5c58a 93 {
sunyiming 1:6465a3f5c58a 94 struct tcp_pcb *pcb, *prev;
sunyiming 1:6465a3f5c58a 95 struct tcp_pcb_listen *lpcb;
sunyiming 1:6465a3f5c58a 96 #if SO_REUSE
sunyiming 1:6465a3f5c58a 97 struct tcp_pcb *lpcb_prev = NULL;
sunyiming 1:6465a3f5c58a 98 struct tcp_pcb_listen *lpcb_any = NULL;
sunyiming 1:6465a3f5c58a 99 #endif /* SO_REUSE */
sunyiming 1:6465a3f5c58a 100 u8_t hdrlen;
sunyiming 1:6465a3f5c58a 101 err_t err;
sunyiming 1:6465a3f5c58a 102
sunyiming 1:6465a3f5c58a 103 PERF_START;
sunyiming 1:6465a3f5c58a 104
sunyiming 1:6465a3f5c58a 105 TCP_STATS_INC(tcp.recv);
sunyiming 1:6465a3f5c58a 106 snmp_inc_tcpinsegs();
sunyiming 1:6465a3f5c58a 107
sunyiming 1:6465a3f5c58a 108 iphdr = (struct ip_hdr *)p->payload;
sunyiming 1:6465a3f5c58a 109 tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
sunyiming 1:6465a3f5c58a 110
sunyiming 1:6465a3f5c58a 111 #if TCP_INPUT_DEBUG
sunyiming 1:6465a3f5c58a 112 tcp_debug_print(tcphdr);
sunyiming 1:6465a3f5c58a 113 #endif
sunyiming 1:6465a3f5c58a 114
sunyiming 1:6465a3f5c58a 115 /* remove header from payload */
sunyiming 1:6465a3f5c58a 116 if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
sunyiming 1:6465a3f5c58a 117 /* drop short packets */
sunyiming 1:6465a3f5c58a 118 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
sunyiming 1:6465a3f5c58a 119 TCP_STATS_INC(tcp.lenerr);
sunyiming 1:6465a3f5c58a 120 TCP_STATS_INC(tcp.drop);
sunyiming 1:6465a3f5c58a 121 snmp_inc_tcpinerrs();
sunyiming 1:6465a3f5c58a 122 pbuf_free(p);
sunyiming 1:6465a3f5c58a 123 return;
sunyiming 1:6465a3f5c58a 124 }
sunyiming 1:6465a3f5c58a 125
sunyiming 1:6465a3f5c58a 126 /* Don't even process incoming broadcasts/multicasts. */
sunyiming 1:6465a3f5c58a 127 if (ip_addr_isbroadcast(&current_iphdr_dest, inp) ||
sunyiming 1:6465a3f5c58a 128 ip_addr_ismulticast(&current_iphdr_dest)) {
sunyiming 1:6465a3f5c58a 129 TCP_STATS_INC(tcp.proterr);
sunyiming 1:6465a3f5c58a 130 TCP_STATS_INC(tcp.drop);
sunyiming 1:6465a3f5c58a 131 snmp_inc_tcpinerrs();
sunyiming 1:6465a3f5c58a 132 pbuf_free(p);
sunyiming 1:6465a3f5c58a 133 return;
sunyiming 1:6465a3f5c58a 134 }
sunyiming 1:6465a3f5c58a 135
sunyiming 1:6465a3f5c58a 136 #if CHECKSUM_CHECK_TCP
sunyiming 1:6465a3f5c58a 137 /* Verify TCP checksum. */
sunyiming 1:6465a3f5c58a 138 if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
sunyiming 1:6465a3f5c58a 139 IP_PROTO_TCP, p->tot_len) != 0) {
sunyiming 1:6465a3f5c58a 140 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
sunyiming 1:6465a3f5c58a 141 inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
sunyiming 1:6465a3f5c58a 142 IP_PROTO_TCP, p->tot_len)));
sunyiming 1:6465a3f5c58a 143 #if TCP_DEBUG
sunyiming 1:6465a3f5c58a 144 tcp_debug_print(tcphdr);
sunyiming 1:6465a3f5c58a 145 #endif /* TCP_DEBUG */
sunyiming 1:6465a3f5c58a 146 TCP_STATS_INC(tcp.chkerr);
sunyiming 1:6465a3f5c58a 147 TCP_STATS_INC(tcp.drop);
sunyiming 1:6465a3f5c58a 148 snmp_inc_tcpinerrs();
sunyiming 1:6465a3f5c58a 149 pbuf_free(p);
sunyiming 1:6465a3f5c58a 150 return;
sunyiming 1:6465a3f5c58a 151 }
sunyiming 1:6465a3f5c58a 152 #endif
sunyiming 1:6465a3f5c58a 153
sunyiming 1:6465a3f5c58a 154 /* Move the payload pointer in the pbuf so that it points to the
sunyiming 1:6465a3f5c58a 155 TCP data instead of the TCP header. */
sunyiming 1:6465a3f5c58a 156 hdrlen = TCPH_HDRLEN(tcphdr);
sunyiming 1:6465a3f5c58a 157 if(pbuf_header(p, -(hdrlen * 4))){
sunyiming 1:6465a3f5c58a 158 /* drop short packets */
sunyiming 1:6465a3f5c58a 159 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
sunyiming 1:6465a3f5c58a 160 TCP_STATS_INC(tcp.lenerr);
sunyiming 1:6465a3f5c58a 161 TCP_STATS_INC(tcp.drop);
sunyiming 1:6465a3f5c58a 162 snmp_inc_tcpinerrs();
sunyiming 1:6465a3f5c58a 163 pbuf_free(p);
sunyiming 1:6465a3f5c58a 164 return;
sunyiming 1:6465a3f5c58a 165 }
sunyiming 1:6465a3f5c58a 166
sunyiming 1:6465a3f5c58a 167 /* Convert fields in TCP header to host byte order. */
sunyiming 1:6465a3f5c58a 168 tcphdr->src = ntohs(tcphdr->src);
sunyiming 1:6465a3f5c58a 169 tcphdr->dest = ntohs(tcphdr->dest);
sunyiming 1:6465a3f5c58a 170 seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
sunyiming 1:6465a3f5c58a 171 ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
sunyiming 1:6465a3f5c58a 172 tcphdr->wnd = ntohs(tcphdr->wnd);
sunyiming 1:6465a3f5c58a 173
sunyiming 1:6465a3f5c58a 174 flags = TCPH_FLAGS(tcphdr);
sunyiming 1:6465a3f5c58a 175 tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);
sunyiming 1:6465a3f5c58a 176
sunyiming 1:6465a3f5c58a 177 /* Demultiplex an incoming segment. First, we check if it is destined
sunyiming 1:6465a3f5c58a 178 for an active connection. */
sunyiming 1:6465a3f5c58a 179 prev = NULL;
sunyiming 1:6465a3f5c58a 180
sunyiming 1:6465a3f5c58a 181
sunyiming 1:6465a3f5c58a 182 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
sunyiming 1:6465a3f5c58a 183 LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
sunyiming 1:6465a3f5c58a 184 LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
sunyiming 1:6465a3f5c58a 185 LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
sunyiming 1:6465a3f5c58a 186 if (pcb->remote_port == tcphdr->src &&
sunyiming 1:6465a3f5c58a 187 pcb->local_port == tcphdr->dest &&
sunyiming 1:6465a3f5c58a 188 ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
sunyiming 1:6465a3f5c58a 189 ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
sunyiming 1:6465a3f5c58a 190
sunyiming 1:6465a3f5c58a 191 /* Move this PCB to the front of the list so that subsequent
sunyiming 1:6465a3f5c58a 192 lookups will be faster (we exploit locality in TCP segment
sunyiming 1:6465a3f5c58a 193 arrivals). */
sunyiming 1:6465a3f5c58a 194 LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
sunyiming 1:6465a3f5c58a 195 if (prev != NULL) {
sunyiming 1:6465a3f5c58a 196 prev->next = pcb->next;
sunyiming 1:6465a3f5c58a 197 pcb->next = tcp_active_pcbs;
sunyiming 1:6465a3f5c58a 198 tcp_active_pcbs = pcb;
sunyiming 1:6465a3f5c58a 199 }
sunyiming 1:6465a3f5c58a 200 LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
sunyiming 1:6465a3f5c58a 201 break;
sunyiming 1:6465a3f5c58a 202 }
sunyiming 1:6465a3f5c58a 203 prev = pcb;
sunyiming 1:6465a3f5c58a 204 }
sunyiming 1:6465a3f5c58a 205
sunyiming 1:6465a3f5c58a 206 if (pcb == NULL) {
sunyiming 1:6465a3f5c58a 207 /* If it did not go to an active connection, we check the connections
sunyiming 1:6465a3f5c58a 208 in the TIME-WAIT state. */
sunyiming 1:6465a3f5c58a 209 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
sunyiming 1:6465a3f5c58a 210 LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
sunyiming 1:6465a3f5c58a 211 if (pcb->remote_port == tcphdr->src &&
sunyiming 1:6465a3f5c58a 212 pcb->local_port == tcphdr->dest &&
sunyiming 1:6465a3f5c58a 213 ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
sunyiming 1:6465a3f5c58a 214 ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
sunyiming 1:6465a3f5c58a 215 /* We don't really care enough to move this PCB to the front
sunyiming 1:6465a3f5c58a 216 of the list since we are not very likely to receive that
sunyiming 1:6465a3f5c58a 217 many segments for connections in TIME-WAIT. */
sunyiming 1:6465a3f5c58a 218 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
sunyiming 1:6465a3f5c58a 219 tcp_timewait_input(pcb);
sunyiming 1:6465a3f5c58a 220 pbuf_free(p);
sunyiming 1:6465a3f5c58a 221 return;
sunyiming 1:6465a3f5c58a 222 }
sunyiming 1:6465a3f5c58a 223 }
sunyiming 1:6465a3f5c58a 224
sunyiming 1:6465a3f5c58a 225 /* Finally, if we still did not get a match, we check all PCBs that
sunyiming 1:6465a3f5c58a 226 are LISTENing for incoming connections. */
sunyiming 1:6465a3f5c58a 227 prev = NULL;
sunyiming 1:6465a3f5c58a 228 for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
sunyiming 1:6465a3f5c58a 229 if (lpcb->local_port == tcphdr->dest) {
sunyiming 1:6465a3f5c58a 230 #if SO_REUSE
sunyiming 1:6465a3f5c58a 231 if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
sunyiming 1:6465a3f5c58a 232 /* found an exact match */
sunyiming 1:6465a3f5c58a 233 break;
sunyiming 1:6465a3f5c58a 234 } else if(ip_addr_isany(&(lpcb->local_ip))) {
sunyiming 1:6465a3f5c58a 235 /* found an ANY-match */
sunyiming 1:6465a3f5c58a 236 lpcb_any = lpcb;
sunyiming 1:6465a3f5c58a 237 lpcb_prev = prev;
sunyiming 1:6465a3f5c58a 238 }
sunyiming 1:6465a3f5c58a 239 #else /* SO_REUSE */
sunyiming 1:6465a3f5c58a 240 if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) ||
sunyiming 1:6465a3f5c58a 241 ip_addr_isany(&(lpcb->local_ip))) {
sunyiming 1:6465a3f5c58a 242 /* found a match */
sunyiming 1:6465a3f5c58a 243 break;
sunyiming 1:6465a3f5c58a 244 }
sunyiming 1:6465a3f5c58a 245 #endif /* SO_REUSE */
sunyiming 1:6465a3f5c58a 246 }
sunyiming 1:6465a3f5c58a 247 prev = (struct tcp_pcb *)lpcb;
sunyiming 1:6465a3f5c58a 248 }
sunyiming 1:6465a3f5c58a 249 #if SO_REUSE
sunyiming 1:6465a3f5c58a 250 /* first try specific local IP */
sunyiming 1:6465a3f5c58a 251 if (lpcb == NULL) {
sunyiming 1:6465a3f5c58a 252 /* only pass to ANY if no specific local IP has been found */
sunyiming 1:6465a3f5c58a 253 lpcb = lpcb_any;
sunyiming 1:6465a3f5c58a 254 prev = lpcb_prev;
sunyiming 1:6465a3f5c58a 255 }
sunyiming 1:6465a3f5c58a 256 #endif /* SO_REUSE */
sunyiming 1:6465a3f5c58a 257 if (lpcb != NULL) {
sunyiming 1:6465a3f5c58a 258 /* Move this PCB to the front of the list so that subsequent
sunyiming 1:6465a3f5c58a 259 lookups will be faster (we exploit locality in TCP segment
sunyiming 1:6465a3f5c58a 260 arrivals). */
sunyiming 1:6465a3f5c58a 261 if (prev != NULL) {
sunyiming 1:6465a3f5c58a 262 ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
sunyiming 1:6465a3f5c58a 263 /* our successor is the remainder of the listening list */
sunyiming 1:6465a3f5c58a 264 lpcb->next = tcp_listen_pcbs.listen_pcbs;
sunyiming 1:6465a3f5c58a 265 /* put this listening pcb at the head of the listening list */
sunyiming 1:6465a3f5c58a 266 tcp_listen_pcbs.listen_pcbs = lpcb;
sunyiming 1:6465a3f5c58a 267 }
sunyiming 1:6465a3f5c58a 268
sunyiming 1:6465a3f5c58a 269 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
sunyiming 1:6465a3f5c58a 270 tcp_listen_input(lpcb);
sunyiming 1:6465a3f5c58a 271 pbuf_free(p);
sunyiming 1:6465a3f5c58a 272 return;
sunyiming 1:6465a3f5c58a 273 }
sunyiming 1:6465a3f5c58a 274 }
sunyiming 1:6465a3f5c58a 275
sunyiming 1:6465a3f5c58a 276 #if TCP_INPUT_DEBUG
sunyiming 1:6465a3f5c58a 277 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
sunyiming 1:6465a3f5c58a 278 tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
sunyiming 1:6465a3f5c58a 279 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
sunyiming 1:6465a3f5c58a 280 #endif /* TCP_INPUT_DEBUG */
sunyiming 1:6465a3f5c58a 281
sunyiming 1:6465a3f5c58a 282
sunyiming 1:6465a3f5c58a 283 if (pcb != NULL) {
sunyiming 1:6465a3f5c58a 284 /* The incoming segment belongs to a connection. */
sunyiming 1:6465a3f5c58a 285 #if TCP_INPUT_DEBUG
sunyiming 1:6465a3f5c58a 286 #if TCP_DEBUG
sunyiming 1:6465a3f5c58a 287 tcp_debug_print_state(pcb->state);
sunyiming 1:6465a3f5c58a 288 #endif /* TCP_DEBUG */
sunyiming 1:6465a3f5c58a 289 #endif /* TCP_INPUT_DEBUG */
sunyiming 1:6465a3f5c58a 290
sunyiming 1:6465a3f5c58a 291 /* Set up a tcp_seg structure. */
sunyiming 1:6465a3f5c58a 292 inseg.next = NULL;
sunyiming 1:6465a3f5c58a 293 inseg.len = p->tot_len;
sunyiming 1:6465a3f5c58a 294 inseg.p = p;
sunyiming 1:6465a3f5c58a 295 inseg.tcphdr = tcphdr;
sunyiming 1:6465a3f5c58a 296
sunyiming 1:6465a3f5c58a 297 recv_data = NULL;
sunyiming 1:6465a3f5c58a 298 recv_flags = 0;
sunyiming 1:6465a3f5c58a 299
sunyiming 1:6465a3f5c58a 300 /* If there is data which was previously "refused" by upper layer */
sunyiming 1:6465a3f5c58a 301 if (pcb->refused_data != NULL) {
sunyiming 1:6465a3f5c58a 302 /* Notify again application with data previously received. */
sunyiming 1:6465a3f5c58a 303 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
sunyiming 1:6465a3f5c58a 304 TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
sunyiming 1:6465a3f5c58a 305 if (err == ERR_OK) {
sunyiming 1:6465a3f5c58a 306 pcb->refused_data = NULL;
sunyiming 1:6465a3f5c58a 307 } else if ((err == ERR_ABRT) || (tcplen > 0)) {
sunyiming 1:6465a3f5c58a 308 /* if err == ERR_ABRT, 'pcb' is already deallocated */
sunyiming 1:6465a3f5c58a 309 /* Drop incoming packets because pcb is "full" (only if the incoming
sunyiming 1:6465a3f5c58a 310 segment contains data). */
sunyiming 1:6465a3f5c58a 311 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
sunyiming 1:6465a3f5c58a 312 TCP_STATS_INC(tcp.drop);
sunyiming 1:6465a3f5c58a 313 snmp_inc_tcpinerrs();
sunyiming 1:6465a3f5c58a 314 pbuf_free(p);
sunyiming 1:6465a3f5c58a 315 return;
sunyiming 1:6465a3f5c58a 316 }
sunyiming 1:6465a3f5c58a 317 }
sunyiming 1:6465a3f5c58a 318 tcp_input_pcb = pcb;
sunyiming 1:6465a3f5c58a 319 err = tcp_process(pcb);
sunyiming 1:6465a3f5c58a 320 /* A return value of ERR_ABRT means that tcp_abort() was called
sunyiming 1:6465a3f5c58a 321 and that the pcb has been freed. If so, we don't do anything. */
sunyiming 1:6465a3f5c58a 322 if (err != ERR_ABRT) {
sunyiming 1:6465a3f5c58a 323 if (recv_flags & TF_RESET) {
sunyiming 1:6465a3f5c58a 324 /* TF_RESET means that the connection was reset by the other
sunyiming 1:6465a3f5c58a 325 end. We then call the error callback to inform the
sunyiming 1:6465a3f5c58a 326 application that the connection is dead before we
sunyiming 1:6465a3f5c58a 327 deallocate the PCB. */
sunyiming 1:6465a3f5c58a 328 TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
sunyiming 1:6465a3f5c58a 329 tcp_pcb_remove(&tcp_active_pcbs, pcb);
sunyiming 1:6465a3f5c58a 330 memp_free(MEMP_TCP_PCB, pcb);
sunyiming 1:6465a3f5c58a 331 } else if (recv_flags & TF_CLOSED) {
sunyiming 1:6465a3f5c58a 332 /* The connection has been closed and we will deallocate the
sunyiming 1:6465a3f5c58a 333 PCB. */
sunyiming 1:6465a3f5c58a 334 tcp_pcb_remove(&tcp_active_pcbs, pcb);
sunyiming 1:6465a3f5c58a 335 memp_free(MEMP_TCP_PCB, pcb);
sunyiming 1:6465a3f5c58a 336 } else {
sunyiming 1:6465a3f5c58a 337 err = ERR_OK;
sunyiming 1:6465a3f5c58a 338 /* If the application has registered a "sent" function to be
sunyiming 1:6465a3f5c58a 339 called when new send buffer space is available, we call it
sunyiming 1:6465a3f5c58a 340 now. */
sunyiming 1:6465a3f5c58a 341 if (pcb->acked > 0) {
sunyiming 1:6465a3f5c58a 342 TCP_EVENT_SENT(pcb, pcb->acked, err);
sunyiming 1:6465a3f5c58a 343 if (err == ERR_ABRT) {
sunyiming 1:6465a3f5c58a 344 goto aborted;
sunyiming 1:6465a3f5c58a 345 }
sunyiming 1:6465a3f5c58a 346 }
sunyiming 1:6465a3f5c58a 347
sunyiming 1:6465a3f5c58a 348 if (recv_data != NULL) {
sunyiming 1:6465a3f5c58a 349 LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
sunyiming 1:6465a3f5c58a 350 if (pcb->flags & TF_RXCLOSED) {
sunyiming 1:6465a3f5c58a 351 /* received data although already closed -> abort (send RST) to
sunyiming 1:6465a3f5c58a 352 notify the remote host that not all data has been processed */
sunyiming 1:6465a3f5c58a 353 pbuf_free(recv_data);
sunyiming 1:6465a3f5c58a 354 tcp_abort(pcb);
sunyiming 1:6465a3f5c58a 355 goto aborted;
sunyiming 1:6465a3f5c58a 356 }
sunyiming 1:6465a3f5c58a 357 if (flags & TCP_PSH) {
sunyiming 1:6465a3f5c58a 358 recv_data->flags |= PBUF_FLAG_PUSH;
sunyiming 1:6465a3f5c58a 359 }
sunyiming 1:6465a3f5c58a 360
sunyiming 1:6465a3f5c58a 361 /* Notify application that data has been received. */
sunyiming 1:6465a3f5c58a 362 TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
sunyiming 1:6465a3f5c58a 363 if (err == ERR_ABRT) {
sunyiming 1:6465a3f5c58a 364 goto aborted;
sunyiming 1:6465a3f5c58a 365 }
sunyiming 1:6465a3f5c58a 366
sunyiming 1:6465a3f5c58a 367 /* If the upper layer can't receive this data, store it */
sunyiming 1:6465a3f5c58a 368 if (err != ERR_OK) {
sunyiming 1:6465a3f5c58a 369 pcb->refused_data = recv_data;
sunyiming 1:6465a3f5c58a 370 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
sunyiming 1:6465a3f5c58a 371 }
sunyiming 1:6465a3f5c58a 372 }
sunyiming 1:6465a3f5c58a 373
sunyiming 1:6465a3f5c58a 374 /* If a FIN segment was received, we call the callback
sunyiming 1:6465a3f5c58a 375 function with a NULL buffer to indicate EOF. */
sunyiming 1:6465a3f5c58a 376 if (recv_flags & TF_GOT_FIN) {
sunyiming 1:6465a3f5c58a 377 /* correct rcv_wnd as the application won't call tcp_recved()
sunyiming 1:6465a3f5c58a 378 for the FIN's seqno */
sunyiming 1:6465a3f5c58a 379 if (pcb->rcv_wnd != TCP_WND) {
sunyiming 1:6465a3f5c58a 380 pcb->rcv_wnd++;
sunyiming 1:6465a3f5c58a 381 }
sunyiming 1:6465a3f5c58a 382 TCP_EVENT_CLOSED(pcb, err);
sunyiming 1:6465a3f5c58a 383 if (err == ERR_ABRT) {
sunyiming 1:6465a3f5c58a 384 goto aborted;
sunyiming 1:6465a3f5c58a 385 }
sunyiming 1:6465a3f5c58a 386 }
sunyiming 1:6465a3f5c58a 387
sunyiming 1:6465a3f5c58a 388 tcp_input_pcb = NULL;
sunyiming 1:6465a3f5c58a 389 /* Try to send something out. */
sunyiming 1:6465a3f5c58a 390 tcp_output(pcb);
sunyiming 1:6465a3f5c58a 391 #if TCP_INPUT_DEBUG
sunyiming 1:6465a3f5c58a 392 #if TCP_DEBUG
sunyiming 1:6465a3f5c58a 393 tcp_debug_print_state(pcb->state);
sunyiming 1:6465a3f5c58a 394 #endif /* TCP_DEBUG */
sunyiming 1:6465a3f5c58a 395 #endif /* TCP_INPUT_DEBUG */
sunyiming 1:6465a3f5c58a 396 }
sunyiming 1:6465a3f5c58a 397 }
sunyiming 1:6465a3f5c58a 398 /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
sunyiming 1:6465a3f5c58a 399 Below this line, 'pcb' may not be dereferenced! */
sunyiming 1:6465a3f5c58a 400 aborted:
sunyiming 1:6465a3f5c58a 401 tcp_input_pcb = NULL;
sunyiming 1:6465a3f5c58a 402 recv_data = NULL;
sunyiming 1:6465a3f5c58a 403
sunyiming 1:6465a3f5c58a 404 /* give up our reference to inseg.p */
sunyiming 1:6465a3f5c58a 405 if (inseg.p != NULL)
sunyiming 1:6465a3f5c58a 406 {
sunyiming 1:6465a3f5c58a 407 pbuf_free(inseg.p);
sunyiming 1:6465a3f5c58a 408 inseg.p = NULL;
sunyiming 1:6465a3f5c58a 409 }
sunyiming 1:6465a3f5c58a 410 } else {
sunyiming 1:6465a3f5c58a 411
sunyiming 1:6465a3f5c58a 412 /* If no matching PCB was found, send a TCP RST (reset) to the
sunyiming 1:6465a3f5c58a 413 sender. */
sunyiming 1:6465a3f5c58a 414 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
sunyiming 1:6465a3f5c58a 415 if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
sunyiming 1:6465a3f5c58a 416 TCP_STATS_INC(tcp.proterr);
sunyiming 1:6465a3f5c58a 417 TCP_STATS_INC(tcp.drop);
sunyiming 1:6465a3f5c58a 418 tcp_rst(ackno, seqno + tcplen,
sunyiming 1:6465a3f5c58a 419 ip_current_dest_addr(), ip_current_src_addr(),
sunyiming 1:6465a3f5c58a 420 tcphdr->dest, tcphdr->src);
sunyiming 1:6465a3f5c58a 421 }
sunyiming 1:6465a3f5c58a 422 pbuf_free(p);
sunyiming 1:6465a3f5c58a 423 }
sunyiming 1:6465a3f5c58a 424
sunyiming 1:6465a3f5c58a 425 LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
sunyiming 1:6465a3f5c58a 426 PERF_STOP("tcp_input");
sunyiming 1:6465a3f5c58a 427 }
sunyiming 1:6465a3f5c58a 428
sunyiming 1:6465a3f5c58a 429 /**
sunyiming 1:6465a3f5c58a 430 * Called by tcp_input() when a segment arrives for a listening
sunyiming 1:6465a3f5c58a 431 * connection (from tcp_input()).
sunyiming 1:6465a3f5c58a 432 *
sunyiming 1:6465a3f5c58a 433 * @param pcb the tcp_pcb_listen for which a segment arrived
sunyiming 1:6465a3f5c58a 434 * @return ERR_OK if the segment was processed
sunyiming 1:6465a3f5c58a 435 * another err_t on error
sunyiming 1:6465a3f5c58a 436 *
sunyiming 1:6465a3f5c58a 437 * @note the return value is not (yet?) used in tcp_input()
sunyiming 1:6465a3f5c58a 438 * @note the segment which arrived is saved in global variables, therefore only the pcb
sunyiming 1:6465a3f5c58a 439 * involved is passed as a parameter to this function
sunyiming 1:6465a3f5c58a 440 */
sunyiming 1:6465a3f5c58a 441 static err_t
sunyiming 1:6465a3f5c58a 442 tcp_listen_input(struct tcp_pcb_listen *pcb)
sunyiming 1:6465a3f5c58a 443 {
sunyiming 1:6465a3f5c58a 444 struct tcp_pcb *npcb;
sunyiming 1:6465a3f5c58a 445 err_t rc;
sunyiming 1:6465a3f5c58a 446
sunyiming 1:6465a3f5c58a 447 /* In the LISTEN state, we check for incoming SYN segments,
sunyiming 1:6465a3f5c58a 448 creates a new PCB, and responds with a SYN|ACK. */
sunyiming 1:6465a3f5c58a 449 if (flags & TCP_ACK) {
sunyiming 1:6465a3f5c58a 450 /* For incoming segments with the ACK flag set, respond with a
sunyiming 1:6465a3f5c58a 451 RST. */
sunyiming 1:6465a3f5c58a 452 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
sunyiming 1:6465a3f5c58a 453 tcp_rst(ackno + 1, seqno + tcplen,
sunyiming 1:6465a3f5c58a 454 ip_current_dest_addr(), ip_current_src_addr(),
sunyiming 1:6465a3f5c58a 455 tcphdr->dest, tcphdr->src);
sunyiming 1:6465a3f5c58a 456 } else if (flags & TCP_SYN) {
sunyiming 1:6465a3f5c58a 457 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
sunyiming 1:6465a3f5c58a 458 #if TCP_LISTEN_BACKLOG
sunyiming 1:6465a3f5c58a 459 if (pcb->accepts_pending >= pcb->backlog) {
sunyiming 1:6465a3f5c58a 460 LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
sunyiming 1:6465a3f5c58a 461 return ERR_ABRT;
sunyiming 1:6465a3f5c58a 462 }
sunyiming 1:6465a3f5c58a 463 #endif /* TCP_LISTEN_BACKLOG */
sunyiming 1:6465a3f5c58a 464 npcb = tcp_alloc(pcb->prio);
sunyiming 1:6465a3f5c58a 465 /* If a new PCB could not be created (probably due to lack of memory),
sunyiming 1:6465a3f5c58a 466 we don't do anything, but rely on the sender will retransmit the
sunyiming 1:6465a3f5c58a 467 SYN at a time when we have more memory available. */
sunyiming 1:6465a3f5c58a 468 if (npcb == NULL) {
sunyiming 1:6465a3f5c58a 469 LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
sunyiming 1:6465a3f5c58a 470 TCP_STATS_INC(tcp.memerr);
sunyiming 1:6465a3f5c58a 471 return ERR_MEM;
sunyiming 1:6465a3f5c58a 472 }
sunyiming 1:6465a3f5c58a 473 #if TCP_LISTEN_BACKLOG
sunyiming 1:6465a3f5c58a 474 pcb->accepts_pending++;
sunyiming 1:6465a3f5c58a 475 #endif /* TCP_LISTEN_BACKLOG */
sunyiming 1:6465a3f5c58a 476 /* Set up the new PCB. */
sunyiming 1:6465a3f5c58a 477 ip_addr_copy(npcb->local_ip, current_iphdr_dest);
sunyiming 1:6465a3f5c58a 478 npcb->local_port = pcb->local_port;
sunyiming 1:6465a3f5c58a 479 ip_addr_copy(npcb->remote_ip, current_iphdr_src);
sunyiming 1:6465a3f5c58a 480 npcb->remote_port = tcphdr->src;
sunyiming 1:6465a3f5c58a 481 npcb->state = SYN_RCVD;
sunyiming 1:6465a3f5c58a 482 npcb->rcv_nxt = seqno + 1;
sunyiming 1:6465a3f5c58a 483 npcb->rcv_ann_right_edge = npcb->rcv_nxt;
sunyiming 1:6465a3f5c58a 484 npcb->snd_wnd = tcphdr->wnd;
sunyiming 1:6465a3f5c58a 485 npcb->ssthresh = npcb->snd_wnd;
sunyiming 1:6465a3f5c58a 486 npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
sunyiming 1:6465a3f5c58a 487 npcb->callback_arg = pcb->callback_arg;
sunyiming 1:6465a3f5c58a 488 #if LWIP_CALLBACK_API
sunyiming 1:6465a3f5c58a 489 npcb->accept = pcb->accept;
sunyiming 1:6465a3f5c58a 490 #endif /* LWIP_CALLBACK_API */
sunyiming 1:6465a3f5c58a 491 /* inherit socket options */
sunyiming 1:6465a3f5c58a 492 npcb->so_options = pcb->so_options & SOF_INHERITED;
sunyiming 1:6465a3f5c58a 493 /* Register the new PCB so that we can begin receiving segments
sunyiming 1:6465a3f5c58a 494 for it. */
sunyiming 1:6465a3f5c58a 495 TCP_REG(&tcp_active_pcbs, npcb);
sunyiming 1:6465a3f5c58a 496
sunyiming 1:6465a3f5c58a 497 /* Parse any options in the SYN. */
sunyiming 1:6465a3f5c58a 498 tcp_parseopt(npcb);
sunyiming 1:6465a3f5c58a 499 #if TCP_CALCULATE_EFF_SEND_MSS
sunyiming 1:6465a3f5c58a 500 npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
sunyiming 1:6465a3f5c58a 501 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
sunyiming 1:6465a3f5c58a 502
sunyiming 1:6465a3f5c58a 503 snmp_inc_tcppassiveopens();
sunyiming 1:6465a3f5c58a 504
sunyiming 1:6465a3f5c58a 505 /* Send a SYN|ACK together with the MSS option. */
sunyiming 1:6465a3f5c58a 506 rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
sunyiming 1:6465a3f5c58a 507 if (rc != ERR_OK) {
sunyiming 1:6465a3f5c58a 508 tcp_abandon(npcb, 0);
sunyiming 1:6465a3f5c58a 509 return rc;
sunyiming 1:6465a3f5c58a 510 }
sunyiming 1:6465a3f5c58a 511 return tcp_output(npcb);
sunyiming 1:6465a3f5c58a 512 }
sunyiming 1:6465a3f5c58a 513 return ERR_OK;
sunyiming 1:6465a3f5c58a 514 }
sunyiming 1:6465a3f5c58a 515
sunyiming 1:6465a3f5c58a 516 /**
sunyiming 1:6465a3f5c58a 517 * Called by tcp_input() when a segment arrives for a connection in
sunyiming 1:6465a3f5c58a 518 * TIME_WAIT.
sunyiming 1:6465a3f5c58a 519 *
sunyiming 1:6465a3f5c58a 520 * @param pcb the tcp_pcb for which a segment arrived
sunyiming 1:6465a3f5c58a 521 *
sunyiming 1:6465a3f5c58a 522 * @note the segment which arrived is saved in global variables, therefore only the pcb
sunyiming 1:6465a3f5c58a 523 * involved is passed as a parameter to this function
sunyiming 1:6465a3f5c58a 524 */
sunyiming 1:6465a3f5c58a 525 static err_t
sunyiming 1:6465a3f5c58a 526 tcp_timewait_input(struct tcp_pcb *pcb)
sunyiming 1:6465a3f5c58a 527 {
sunyiming 1:6465a3f5c58a 528 /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
sunyiming 1:6465a3f5c58a 529 /* RFC 793 3.9 Event Processing - Segment Arrives:
sunyiming 1:6465a3f5c58a 530 * - first check sequence number - we skip that one in TIME_WAIT (always
sunyiming 1:6465a3f5c58a 531 * acceptable since we only send ACKs)
sunyiming 1:6465a3f5c58a 532 * - second check the RST bit (... return) */
sunyiming 1:6465a3f5c58a 533 if (flags & TCP_RST) {
sunyiming 1:6465a3f5c58a 534 return ERR_OK;
sunyiming 1:6465a3f5c58a 535 }
sunyiming 1:6465a3f5c58a 536 /* - fourth, check the SYN bit, */
sunyiming 1:6465a3f5c58a 537 if (flags & TCP_SYN) {
sunyiming 1:6465a3f5c58a 538 /* If an incoming segment is not acceptable, an acknowledgment
sunyiming 1:6465a3f5c58a 539 should be sent in reply */
sunyiming 1:6465a3f5c58a 540 if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
sunyiming 1:6465a3f5c58a 541 /* If the SYN is in the window it is an error, send a reset */
sunyiming 1:6465a3f5c58a 542 tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
sunyiming 1:6465a3f5c58a 543 tcphdr->dest, tcphdr->src);
sunyiming 1:6465a3f5c58a 544 return ERR_OK;
sunyiming 1:6465a3f5c58a 545 }
sunyiming 1:6465a3f5c58a 546 } else if (flags & TCP_FIN) {
sunyiming 1:6465a3f5c58a 547 /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
sunyiming 1:6465a3f5c58a 548 Restart the 2 MSL time-wait timeout.*/
sunyiming 1:6465a3f5c58a 549 pcb->tmr = tcp_ticks;
sunyiming 1:6465a3f5c58a 550 }
sunyiming 1:6465a3f5c58a 551
sunyiming 1:6465a3f5c58a 552 if ((tcplen > 0)) {
sunyiming 1:6465a3f5c58a 553 /* Acknowledge data, FIN or out-of-window SYN */
sunyiming 1:6465a3f5c58a 554 pcb->flags |= TF_ACK_NOW;
sunyiming 1:6465a3f5c58a 555 return tcp_output(pcb);
sunyiming 1:6465a3f5c58a 556 }
sunyiming 1:6465a3f5c58a 557 return ERR_OK;
sunyiming 1:6465a3f5c58a 558 }
sunyiming 1:6465a3f5c58a 559
sunyiming 1:6465a3f5c58a 560 /**
sunyiming 1:6465a3f5c58a 561 * Implements the TCP state machine. Called by tcp_input. In some
sunyiming 1:6465a3f5c58a 562 * states tcp_receive() is called to receive data. The tcp_seg
sunyiming 1:6465a3f5c58a 563 * argument will be freed by the caller (tcp_input()) unless the
sunyiming 1:6465a3f5c58a 564 * recv_data pointer in the pcb is set.
sunyiming 1:6465a3f5c58a 565 *
sunyiming 1:6465a3f5c58a 566 * @param pcb the tcp_pcb for which a segment arrived
sunyiming 1:6465a3f5c58a 567 *
sunyiming 1:6465a3f5c58a 568 * @note the segment which arrived is saved in global variables, therefore only the pcb
sunyiming 1:6465a3f5c58a 569 * involved is passed as a parameter to this function
sunyiming 1:6465a3f5c58a 570 */
sunyiming 1:6465a3f5c58a 571 static err_t
sunyiming 1:6465a3f5c58a 572 tcp_process(struct tcp_pcb *pcb)
sunyiming 1:6465a3f5c58a 573 {
sunyiming 1:6465a3f5c58a 574 struct tcp_seg *rseg;
sunyiming 1:6465a3f5c58a 575 u8_t acceptable = 0;
sunyiming 1:6465a3f5c58a 576 err_t err;
sunyiming 1:6465a3f5c58a 577
sunyiming 1:6465a3f5c58a 578 err = ERR_OK;
sunyiming 1:6465a3f5c58a 579
sunyiming 1:6465a3f5c58a 580 /* Process incoming RST segments. */
sunyiming 1:6465a3f5c58a 581 if (flags & TCP_RST) {
sunyiming 1:6465a3f5c58a 582 /* First, determine if the reset is acceptable. */
sunyiming 1:6465a3f5c58a 583 if (pcb->state == SYN_SENT) {
sunyiming 1:6465a3f5c58a 584 if (ackno == pcb->snd_nxt) {
sunyiming 1:6465a3f5c58a 585 acceptable = 1;
sunyiming 1:6465a3f5c58a 586 }
sunyiming 1:6465a3f5c58a 587 } else {
sunyiming 1:6465a3f5c58a 588 if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
sunyiming 1:6465a3f5c58a 589 pcb->rcv_nxt+pcb->rcv_wnd)) {
sunyiming 1:6465a3f5c58a 590 acceptable = 1;
sunyiming 1:6465a3f5c58a 591 }
sunyiming 1:6465a3f5c58a 592 }
sunyiming 1:6465a3f5c58a 593
sunyiming 1:6465a3f5c58a 594 if (acceptable) {
sunyiming 1:6465a3f5c58a 595 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
sunyiming 1:6465a3f5c58a 596 LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
sunyiming 1:6465a3f5c58a 597 recv_flags |= TF_RESET;
sunyiming 1:6465a3f5c58a 598 pcb->flags &= ~TF_ACK_DELAY;
sunyiming 1:6465a3f5c58a 599 return ERR_RST;
sunyiming 1:6465a3f5c58a 600 } else {
sunyiming 1:6465a3f5c58a 601 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
sunyiming 1:6465a3f5c58a 602 seqno, pcb->rcv_nxt));
sunyiming 1:6465a3f5c58a 603 LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
sunyiming 1:6465a3f5c58a 604 seqno, pcb->rcv_nxt));
sunyiming 1:6465a3f5c58a 605 return ERR_OK;
sunyiming 1:6465a3f5c58a 606 }
sunyiming 1:6465a3f5c58a 607 }
sunyiming 1:6465a3f5c58a 608
sunyiming 1:6465a3f5c58a 609 if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
sunyiming 1:6465a3f5c58a 610 /* Cope with new connection attempt after remote end crashed */
sunyiming 1:6465a3f5c58a 611 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 612 return ERR_OK;
sunyiming 1:6465a3f5c58a 613 }
sunyiming 1:6465a3f5c58a 614
sunyiming 1:6465a3f5c58a 615 if ((pcb->flags & TF_RXCLOSED) == 0) {
sunyiming 1:6465a3f5c58a 616 /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
sunyiming 1:6465a3f5c58a 617 pcb->tmr = tcp_ticks;
sunyiming 1:6465a3f5c58a 618 }
sunyiming 1:6465a3f5c58a 619 pcb->keep_cnt_sent = 0;
sunyiming 1:6465a3f5c58a 620
sunyiming 1:6465a3f5c58a 621 tcp_parseopt(pcb);
sunyiming 1:6465a3f5c58a 622
sunyiming 1:6465a3f5c58a 623 /* Do different things depending on the TCP state. */
sunyiming 1:6465a3f5c58a 624 switch (pcb->state) {
sunyiming 1:6465a3f5c58a 625 case SYN_SENT:
sunyiming 1:6465a3f5c58a 626 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
sunyiming 1:6465a3f5c58a 627 pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
sunyiming 1:6465a3f5c58a 628 /* received SYN ACK with expected sequence number? */
sunyiming 1:6465a3f5c58a 629 if ((flags & TCP_ACK) && (flags & TCP_SYN)
sunyiming 1:6465a3f5c58a 630 && ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
sunyiming 1:6465a3f5c58a 631 pcb->snd_buf++;
sunyiming 1:6465a3f5c58a 632 pcb->rcv_nxt = seqno + 1;
sunyiming 1:6465a3f5c58a 633 pcb->rcv_ann_right_edge = pcb->rcv_nxt;
sunyiming 1:6465a3f5c58a 634 pcb->lastack = ackno;
sunyiming 1:6465a3f5c58a 635 pcb->snd_wnd = tcphdr->wnd;
sunyiming 1:6465a3f5c58a 636 pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
sunyiming 1:6465a3f5c58a 637 pcb->state = ESTABLISHED;
sunyiming 1:6465a3f5c58a 638
sunyiming 1:6465a3f5c58a 639 #if TCP_CALCULATE_EFF_SEND_MSS
sunyiming 1:6465a3f5c58a 640 pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
sunyiming 1:6465a3f5c58a 641 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
sunyiming 1:6465a3f5c58a 642
sunyiming 1:6465a3f5c58a 643 /* Set ssthresh again after changing pcb->mss (already set in tcp_connect
sunyiming 1:6465a3f5c58a 644 * but for the default value of pcb->mss) */
sunyiming 1:6465a3f5c58a 645 pcb->ssthresh = pcb->mss * 10;
sunyiming 1:6465a3f5c58a 646
sunyiming 1:6465a3f5c58a 647 pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
sunyiming 1:6465a3f5c58a 648 LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
sunyiming 1:6465a3f5c58a 649 --pcb->snd_queuelen;
sunyiming 1:6465a3f5c58a 650 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
sunyiming 1:6465a3f5c58a 651 rseg = pcb->unacked;
sunyiming 1:6465a3f5c58a 652 pcb->unacked = rseg->next;
sunyiming 1:6465a3f5c58a 653
sunyiming 1:6465a3f5c58a 654 /* If there's nothing left to acknowledge, stop the retransmit
sunyiming 1:6465a3f5c58a 655 timer, otherwise reset it to start again */
sunyiming 1:6465a3f5c58a 656 if(pcb->unacked == NULL)
sunyiming 1:6465a3f5c58a 657 pcb->rtime = -1;
sunyiming 1:6465a3f5c58a 658 else {
sunyiming 1:6465a3f5c58a 659 pcb->rtime = 0;
sunyiming 1:6465a3f5c58a 660 pcb->nrtx = 0;
sunyiming 1:6465a3f5c58a 661 }
sunyiming 1:6465a3f5c58a 662
sunyiming 1:6465a3f5c58a 663 tcp_seg_free(rseg);
sunyiming 1:6465a3f5c58a 664
sunyiming 1:6465a3f5c58a 665 /* Call the user specified function to call when sucessfully
sunyiming 1:6465a3f5c58a 666 * connected. */
sunyiming 1:6465a3f5c58a 667 TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
sunyiming 1:6465a3f5c58a 668 if (err == ERR_ABRT) {
sunyiming 1:6465a3f5c58a 669 return ERR_ABRT;
sunyiming 1:6465a3f5c58a 670 }
sunyiming 1:6465a3f5c58a 671 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 672 }
sunyiming 1:6465a3f5c58a 673 /* received ACK? possibly a half-open connection */
sunyiming 1:6465a3f5c58a 674 else if (flags & TCP_ACK) {
sunyiming 1:6465a3f5c58a 675 /* send a RST to bring the other side in a non-synchronized state. */
sunyiming 1:6465a3f5c58a 676 tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
sunyiming 1:6465a3f5c58a 677 tcphdr->dest, tcphdr->src);
sunyiming 1:6465a3f5c58a 678 }
sunyiming 1:6465a3f5c58a 679 break;
sunyiming 1:6465a3f5c58a 680 case SYN_RCVD:
sunyiming 1:6465a3f5c58a 681 if (flags & TCP_ACK) {
sunyiming 1:6465a3f5c58a 682 /* expected ACK number? */
sunyiming 1:6465a3f5c58a 683 if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
sunyiming 1:6465a3f5c58a 684 u16_t old_cwnd;
sunyiming 1:6465a3f5c58a 685 pcb->state = ESTABLISHED;
sunyiming 1:6465a3f5c58a 686 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
sunyiming 1:6465a3f5c58a 687 #if LWIP_CALLBACK_API
sunyiming 1:6465a3f5c58a 688 LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
sunyiming 1:6465a3f5c58a 689 #endif
sunyiming 1:6465a3f5c58a 690 /* Call the accept function. */
sunyiming 1:6465a3f5c58a 691 TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
sunyiming 1:6465a3f5c58a 692 if (err != ERR_OK) {
sunyiming 1:6465a3f5c58a 693 /* If the accept function returns with an error, we abort
sunyiming 1:6465a3f5c58a 694 * the connection. */
sunyiming 1:6465a3f5c58a 695 /* Already aborted? */
sunyiming 1:6465a3f5c58a 696 if (err != ERR_ABRT) {
sunyiming 1:6465a3f5c58a 697 tcp_abort(pcb);
sunyiming 1:6465a3f5c58a 698 }
sunyiming 1:6465a3f5c58a 699 return ERR_ABRT;
sunyiming 1:6465a3f5c58a 700 }
sunyiming 1:6465a3f5c58a 701 old_cwnd = pcb->cwnd;
sunyiming 1:6465a3f5c58a 702 /* If there was any data contained within this ACK,
sunyiming 1:6465a3f5c58a 703 * we'd better pass it on to the application as well. */
sunyiming 1:6465a3f5c58a 704 tcp_receive(pcb);
sunyiming 1:6465a3f5c58a 705
sunyiming 1:6465a3f5c58a 706 /* Prevent ACK for SYN to generate a sent event */
sunyiming 1:6465a3f5c58a 707 if (pcb->acked != 0) {
sunyiming 1:6465a3f5c58a 708 pcb->acked--;
sunyiming 1:6465a3f5c58a 709 }
sunyiming 1:6465a3f5c58a 710
sunyiming 1:6465a3f5c58a 711 pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
sunyiming 1:6465a3f5c58a 712
sunyiming 1:6465a3f5c58a 713 if (recv_flags & TF_GOT_FIN) {
sunyiming 1:6465a3f5c58a 714 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 715 pcb->state = CLOSE_WAIT;
sunyiming 1:6465a3f5c58a 716 }
sunyiming 1:6465a3f5c58a 717 } else {
sunyiming 1:6465a3f5c58a 718 /* incorrect ACK number, send RST */
sunyiming 1:6465a3f5c58a 719 tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
sunyiming 1:6465a3f5c58a 720 tcphdr->dest, tcphdr->src);
sunyiming 1:6465a3f5c58a 721 }
sunyiming 1:6465a3f5c58a 722 } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
sunyiming 1:6465a3f5c58a 723 /* Looks like another copy of the SYN - retransmit our SYN-ACK */
sunyiming 1:6465a3f5c58a 724 tcp_rexmit(pcb);
sunyiming 1:6465a3f5c58a 725 }
sunyiming 1:6465a3f5c58a 726 break;
sunyiming 1:6465a3f5c58a 727 case CLOSE_WAIT:
sunyiming 1:6465a3f5c58a 728 /* FALLTHROUGH */
sunyiming 1:6465a3f5c58a 729 case ESTABLISHED:
sunyiming 1:6465a3f5c58a 730 tcp_receive(pcb);
sunyiming 1:6465a3f5c58a 731 if (recv_flags & TF_GOT_FIN) { /* passive close */
sunyiming 1:6465a3f5c58a 732 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 733 pcb->state = CLOSE_WAIT;
sunyiming 1:6465a3f5c58a 734 }
sunyiming 1:6465a3f5c58a 735 break;
sunyiming 1:6465a3f5c58a 736 case FIN_WAIT_1:
sunyiming 1:6465a3f5c58a 737 tcp_receive(pcb);
sunyiming 1:6465a3f5c58a 738 if (recv_flags & TF_GOT_FIN) {
sunyiming 1:6465a3f5c58a 739 if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
sunyiming 1:6465a3f5c58a 740 LWIP_DEBUGF(TCP_DEBUG,
sunyiming 1:6465a3f5c58a 741 ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
sunyiming 1:6465a3f5c58a 742 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 743 tcp_pcb_purge(pcb);
sunyiming 1:6465a3f5c58a 744 TCP_RMV(&tcp_active_pcbs, pcb);
sunyiming 1:6465a3f5c58a 745 pcb->state = TIME_WAIT;
sunyiming 1:6465a3f5c58a 746 TCP_REG(&tcp_tw_pcbs, pcb);
sunyiming 1:6465a3f5c58a 747 } else {
sunyiming 1:6465a3f5c58a 748 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 749 pcb->state = CLOSING;
sunyiming 1:6465a3f5c58a 750 }
sunyiming 1:6465a3f5c58a 751 } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
sunyiming 1:6465a3f5c58a 752 pcb->state = FIN_WAIT_2;
sunyiming 1:6465a3f5c58a 753 }
sunyiming 1:6465a3f5c58a 754 break;
sunyiming 1:6465a3f5c58a 755 case FIN_WAIT_2:
sunyiming 1:6465a3f5c58a 756 tcp_receive(pcb);
sunyiming 1:6465a3f5c58a 757 if (recv_flags & TF_GOT_FIN) {
sunyiming 1:6465a3f5c58a 758 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
sunyiming 1:6465a3f5c58a 759 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 760 tcp_pcb_purge(pcb);
sunyiming 1:6465a3f5c58a 761 TCP_RMV(&tcp_active_pcbs, pcb);
sunyiming 1:6465a3f5c58a 762 pcb->state = TIME_WAIT;
sunyiming 1:6465a3f5c58a 763 TCP_REG(&tcp_tw_pcbs, pcb);
sunyiming 1:6465a3f5c58a 764 }
sunyiming 1:6465a3f5c58a 765 break;
sunyiming 1:6465a3f5c58a 766 case CLOSING:
sunyiming 1:6465a3f5c58a 767 tcp_receive(pcb);
sunyiming 1:6465a3f5c58a 768 if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
sunyiming 1:6465a3f5c58a 769 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
sunyiming 1:6465a3f5c58a 770 tcp_pcb_purge(pcb);
sunyiming 1:6465a3f5c58a 771 TCP_RMV(&tcp_active_pcbs, pcb);
sunyiming 1:6465a3f5c58a 772 pcb->state = TIME_WAIT;
sunyiming 1:6465a3f5c58a 773 TCP_REG(&tcp_tw_pcbs, pcb);
sunyiming 1:6465a3f5c58a 774 }
sunyiming 1:6465a3f5c58a 775 break;
sunyiming 1:6465a3f5c58a 776 case LAST_ACK:
sunyiming 1:6465a3f5c58a 777 tcp_receive(pcb);
sunyiming 1:6465a3f5c58a 778 if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
sunyiming 1:6465a3f5c58a 779 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
sunyiming 1:6465a3f5c58a 780 /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
sunyiming 1:6465a3f5c58a 781 recv_flags |= TF_CLOSED;
sunyiming 1:6465a3f5c58a 782 }
sunyiming 1:6465a3f5c58a 783 break;
sunyiming 1:6465a3f5c58a 784 default:
sunyiming 1:6465a3f5c58a 785 break;
sunyiming 1:6465a3f5c58a 786 }
sunyiming 1:6465a3f5c58a 787 return ERR_OK;
sunyiming 1:6465a3f5c58a 788 }
sunyiming 1:6465a3f5c58a 789
sunyiming 1:6465a3f5c58a 790 #if TCP_QUEUE_OOSEQ
sunyiming 1:6465a3f5c58a 791 /**
sunyiming 1:6465a3f5c58a 792 * Insert segment into the list (segments covered with new one will be deleted)
sunyiming 1:6465a3f5c58a 793 *
sunyiming 1:6465a3f5c58a 794 * Called from tcp_receive()
sunyiming 1:6465a3f5c58a 795 */
sunyiming 1:6465a3f5c58a 796 static void
sunyiming 1:6465a3f5c58a 797 tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
sunyiming 1:6465a3f5c58a 798 {
sunyiming 1:6465a3f5c58a 799 struct tcp_seg *old_seg;
sunyiming 1:6465a3f5c58a 800
sunyiming 1:6465a3f5c58a 801 if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 802 /* received segment overlaps all following segments */
sunyiming 1:6465a3f5c58a 803 tcp_segs_free(next);
sunyiming 1:6465a3f5c58a 804 next = NULL;
sunyiming 1:6465a3f5c58a 805 }
sunyiming 1:6465a3f5c58a 806 else {
sunyiming 1:6465a3f5c58a 807 /* delete some following segments
sunyiming 1:6465a3f5c58a 808 oos queue may have segments with FIN flag */
sunyiming 1:6465a3f5c58a 809 while (next &&
sunyiming 1:6465a3f5c58a 810 TCP_SEQ_GEQ((seqno + cseg->len),
sunyiming 1:6465a3f5c58a 811 (next->tcphdr->seqno + next->len))) {
sunyiming 1:6465a3f5c58a 812 /* cseg with FIN already processed */
sunyiming 1:6465a3f5c58a 813 if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 814 TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
sunyiming 1:6465a3f5c58a 815 }
sunyiming 1:6465a3f5c58a 816 old_seg = next;
sunyiming 1:6465a3f5c58a 817 next = next->next;
sunyiming 1:6465a3f5c58a 818 tcp_seg_free(old_seg);
sunyiming 1:6465a3f5c58a 819 }
sunyiming 1:6465a3f5c58a 820 if (next &&
sunyiming 1:6465a3f5c58a 821 TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
sunyiming 1:6465a3f5c58a 822 /* We need to trim the incoming segment. */
sunyiming 1:6465a3f5c58a 823 cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
sunyiming 1:6465a3f5c58a 824 pbuf_realloc(cseg->p, cseg->len);
sunyiming 1:6465a3f5c58a 825 }
sunyiming 1:6465a3f5c58a 826 }
sunyiming 1:6465a3f5c58a 827 cseg->next = next;
sunyiming 1:6465a3f5c58a 828 }
sunyiming 1:6465a3f5c58a 829 #endif /* TCP_QUEUE_OOSEQ */
sunyiming 1:6465a3f5c58a 830
sunyiming 1:6465a3f5c58a 831 /**
sunyiming 1:6465a3f5c58a 832 * Called by tcp_process. Checks if the given segment is an ACK for outstanding
sunyiming 1:6465a3f5c58a 833 * data, and if so frees the memory of the buffered data. Next, is places the
sunyiming 1:6465a3f5c58a 834 * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
sunyiming 1:6465a3f5c58a 835 * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
sunyiming 1:6465a3f5c58a 836 * i it has been removed from the buffer.
sunyiming 1:6465a3f5c58a 837 *
sunyiming 1:6465a3f5c58a 838 * If the incoming segment constitutes an ACK for a segment that was used for RTT
sunyiming 1:6465a3f5c58a 839 * estimation, the RTT is estimated here as well.
sunyiming 1:6465a3f5c58a 840 *
sunyiming 1:6465a3f5c58a 841 * Called from tcp_process().
sunyiming 1:6465a3f5c58a 842 */
sunyiming 1:6465a3f5c58a 843 static void
sunyiming 1:6465a3f5c58a 844 tcp_receive(struct tcp_pcb *pcb)
sunyiming 1:6465a3f5c58a 845 {
sunyiming 1:6465a3f5c58a 846 struct tcp_seg *next;
sunyiming 1:6465a3f5c58a 847 #if TCP_QUEUE_OOSEQ
sunyiming 1:6465a3f5c58a 848 struct tcp_seg *prev, *cseg;
sunyiming 1:6465a3f5c58a 849 #endif /* TCP_QUEUE_OOSEQ */
sunyiming 1:6465a3f5c58a 850 struct pbuf *p;
sunyiming 1:6465a3f5c58a 851 s32_t off;
sunyiming 1:6465a3f5c58a 852 s16_t m;
sunyiming 1:6465a3f5c58a 853 u32_t right_wnd_edge;
sunyiming 1:6465a3f5c58a 854 u16_t new_tot_len;
sunyiming 1:6465a3f5c58a 855 int found_dupack = 0;
sunyiming 1:6465a3f5c58a 856
sunyiming 1:6465a3f5c58a 857 if (flags & TCP_ACK) {
sunyiming 1:6465a3f5c58a 858 right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
sunyiming 1:6465a3f5c58a 859
sunyiming 1:6465a3f5c58a 860 /* Update window. */
sunyiming 1:6465a3f5c58a 861 if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
sunyiming 1:6465a3f5c58a 862 (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
sunyiming 1:6465a3f5c58a 863 (pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
sunyiming 1:6465a3f5c58a 864 pcb->snd_wnd = tcphdr->wnd;
sunyiming 1:6465a3f5c58a 865 pcb->snd_wl1 = seqno;
sunyiming 1:6465a3f5c58a 866 pcb->snd_wl2 = ackno;
sunyiming 1:6465a3f5c58a 867 if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
sunyiming 1:6465a3f5c58a 868 pcb->persist_backoff = 0;
sunyiming 1:6465a3f5c58a 869 }
sunyiming 1:6465a3f5c58a 870 LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
sunyiming 1:6465a3f5c58a 871 #if TCP_WND_DEBUG
sunyiming 1:6465a3f5c58a 872 } else {
sunyiming 1:6465a3f5c58a 873 if (pcb->snd_wnd != tcphdr->wnd) {
sunyiming 1:6465a3f5c58a 874 LWIP_DEBUGF(TCP_WND_DEBUG,
sunyiming 1:6465a3f5c58a 875 ("tcp_receive: no window update lastack %"U32_F" ackno %"
sunyiming 1:6465a3f5c58a 876 U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
sunyiming 1:6465a3f5c58a 877 pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
sunyiming 1:6465a3f5c58a 878 }
sunyiming 1:6465a3f5c58a 879 #endif /* TCP_WND_DEBUG */
sunyiming 1:6465a3f5c58a 880 }
sunyiming 1:6465a3f5c58a 881
sunyiming 1:6465a3f5c58a 882 /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
sunyiming 1:6465a3f5c58a 883 * duplicate ack if:
sunyiming 1:6465a3f5c58a 884 * 1) It doesn't ACK new data
sunyiming 1:6465a3f5c58a 885 * 2) length of received packet is zero (i.e. no payload)
sunyiming 1:6465a3f5c58a 886 * 3) the advertised window hasn't changed
sunyiming 1:6465a3f5c58a 887 * 4) There is outstanding unacknowledged data (retransmission timer running)
sunyiming 1:6465a3f5c58a 888 * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
sunyiming 1:6465a3f5c58a 889 *
sunyiming 1:6465a3f5c58a 890 * If it passes all five, should process as a dupack:
sunyiming 1:6465a3f5c58a 891 * a) dupacks < 3: do nothing
sunyiming 1:6465a3f5c58a 892 * b) dupacks == 3: fast retransmit
sunyiming 1:6465a3f5c58a 893 * c) dupacks > 3: increase cwnd
sunyiming 1:6465a3f5c58a 894 *
sunyiming 1:6465a3f5c58a 895 * If it only passes 1-3, should reset dupack counter (and add to
sunyiming 1:6465a3f5c58a 896 * stats, which we don't do in lwIP)
sunyiming 1:6465a3f5c58a 897 *
sunyiming 1:6465a3f5c58a 898 * If it only passes 1, should reset dupack counter
sunyiming 1:6465a3f5c58a 899 *
sunyiming 1:6465a3f5c58a 900 */
sunyiming 1:6465a3f5c58a 901
sunyiming 1:6465a3f5c58a 902 /* Clause 1 */
sunyiming 1:6465a3f5c58a 903 if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
sunyiming 1:6465a3f5c58a 904 pcb->acked = 0;
sunyiming 1:6465a3f5c58a 905 /* Clause 2 */
sunyiming 1:6465a3f5c58a 906 if (tcplen == 0) {
sunyiming 1:6465a3f5c58a 907 /* Clause 3 */
sunyiming 1:6465a3f5c58a 908 if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
sunyiming 1:6465a3f5c58a 909 /* Clause 4 */
sunyiming 1:6465a3f5c58a 910 if (pcb->rtime >= 0) {
sunyiming 1:6465a3f5c58a 911 /* Clause 5 */
sunyiming 1:6465a3f5c58a 912 if (pcb->lastack == ackno) {
sunyiming 1:6465a3f5c58a 913 found_dupack = 1;
sunyiming 1:6465a3f5c58a 914 if (pcb->dupacks + 1 > pcb->dupacks)
sunyiming 1:6465a3f5c58a 915 ++pcb->dupacks;
sunyiming 1:6465a3f5c58a 916 if (pcb->dupacks > 3) {
sunyiming 1:6465a3f5c58a 917 /* Inflate the congestion window, but not if it means that
sunyiming 1:6465a3f5c58a 918 the value overflows. */
sunyiming 1:6465a3f5c58a 919 if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
sunyiming 1:6465a3f5c58a 920 pcb->cwnd += pcb->mss;
sunyiming 1:6465a3f5c58a 921 }
sunyiming 1:6465a3f5c58a 922 } else if (pcb->dupacks == 3) {
sunyiming 1:6465a3f5c58a 923 /* Do fast retransmit */
sunyiming 1:6465a3f5c58a 924 tcp_rexmit_fast(pcb);
sunyiming 1:6465a3f5c58a 925 }
sunyiming 1:6465a3f5c58a 926 }
sunyiming 1:6465a3f5c58a 927 }
sunyiming 1:6465a3f5c58a 928 }
sunyiming 1:6465a3f5c58a 929 }
sunyiming 1:6465a3f5c58a 930 /* If Clause (1) or more is true, but not a duplicate ack, reset
sunyiming 1:6465a3f5c58a 931 * count of consecutive duplicate acks */
sunyiming 1:6465a3f5c58a 932 if (!found_dupack) {
sunyiming 1:6465a3f5c58a 933 pcb->dupacks = 0;
sunyiming 1:6465a3f5c58a 934 }
sunyiming 1:6465a3f5c58a 935 } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
sunyiming 1:6465a3f5c58a 936 /* We come here when the ACK acknowledges new data. */
sunyiming 1:6465a3f5c58a 937
sunyiming 1:6465a3f5c58a 938 /* Reset the "IN Fast Retransmit" flag, since we are no longer
sunyiming 1:6465a3f5c58a 939 in fast retransmit. Also reset the congestion window to the
sunyiming 1:6465a3f5c58a 940 slow start threshold. */
sunyiming 1:6465a3f5c58a 941 if (pcb->flags & TF_INFR) {
sunyiming 1:6465a3f5c58a 942 pcb->flags &= ~TF_INFR;
sunyiming 1:6465a3f5c58a 943 pcb->cwnd = pcb->ssthresh;
sunyiming 1:6465a3f5c58a 944 }
sunyiming 1:6465a3f5c58a 945
sunyiming 1:6465a3f5c58a 946 /* Reset the number of retransmissions. */
sunyiming 1:6465a3f5c58a 947 pcb->nrtx = 0;
sunyiming 1:6465a3f5c58a 948
sunyiming 1:6465a3f5c58a 949 /* Reset the retransmission time-out. */
sunyiming 1:6465a3f5c58a 950 pcb->rto = (pcb->sa >> 3) + pcb->sv;
sunyiming 1:6465a3f5c58a 951
sunyiming 1:6465a3f5c58a 952 /* Update the send buffer space. Diff between the two can never exceed 64K? */
sunyiming 1:6465a3f5c58a 953 pcb->acked = (u16_t)(ackno - pcb->lastack);
sunyiming 1:6465a3f5c58a 954
sunyiming 1:6465a3f5c58a 955 pcb->snd_buf += pcb->acked;
sunyiming 1:6465a3f5c58a 956
sunyiming 1:6465a3f5c58a 957 /* Reset the fast retransmit variables. */
sunyiming 1:6465a3f5c58a 958 pcb->dupacks = 0;
sunyiming 1:6465a3f5c58a 959 pcb->lastack = ackno;
sunyiming 1:6465a3f5c58a 960
sunyiming 1:6465a3f5c58a 961 /* Update the congestion control variables (cwnd and
sunyiming 1:6465a3f5c58a 962 ssthresh). */
sunyiming 1:6465a3f5c58a 963 if (pcb->state >= ESTABLISHED) {
sunyiming 1:6465a3f5c58a 964 if (pcb->cwnd < pcb->ssthresh) {
sunyiming 1:6465a3f5c58a 965 if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
sunyiming 1:6465a3f5c58a 966 pcb->cwnd += pcb->mss;
sunyiming 1:6465a3f5c58a 967 }
sunyiming 1:6465a3f5c58a 968 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
sunyiming 1:6465a3f5c58a 969 } else {
sunyiming 1:6465a3f5c58a 970 u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
sunyiming 1:6465a3f5c58a 971 if (new_cwnd > pcb->cwnd) {
sunyiming 1:6465a3f5c58a 972 pcb->cwnd = new_cwnd;
sunyiming 1:6465a3f5c58a 973 }
sunyiming 1:6465a3f5c58a 974 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
sunyiming 1:6465a3f5c58a 975 }
sunyiming 1:6465a3f5c58a 976 }
sunyiming 1:6465a3f5c58a 977 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
sunyiming 1:6465a3f5c58a 978 ackno,
sunyiming 1:6465a3f5c58a 979 pcb->unacked != NULL?
sunyiming 1:6465a3f5c58a 980 ntohl(pcb->unacked->tcphdr->seqno): 0,
sunyiming 1:6465a3f5c58a 981 pcb->unacked != NULL?
sunyiming 1:6465a3f5c58a 982 ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
sunyiming 1:6465a3f5c58a 983
sunyiming 1:6465a3f5c58a 984 /* Remove segment from the unacknowledged list if the incoming
sunyiming 1:6465a3f5c58a 985 ACK acknowlegdes them. */
sunyiming 1:6465a3f5c58a 986 while (pcb->unacked != NULL &&
sunyiming 1:6465a3f5c58a 987 TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
sunyiming 1:6465a3f5c58a 988 TCP_TCPLEN(pcb->unacked), ackno)) {
sunyiming 1:6465a3f5c58a 989 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
sunyiming 1:6465a3f5c58a 990 ntohl(pcb->unacked->tcphdr->seqno),
sunyiming 1:6465a3f5c58a 991 ntohl(pcb->unacked->tcphdr->seqno) +
sunyiming 1:6465a3f5c58a 992 TCP_TCPLEN(pcb->unacked)));
sunyiming 1:6465a3f5c58a 993
sunyiming 1:6465a3f5c58a 994 next = pcb->unacked;
sunyiming 1:6465a3f5c58a 995 pcb->unacked = pcb->unacked->next;
sunyiming 1:6465a3f5c58a 996
sunyiming 1:6465a3f5c58a 997 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
sunyiming 1:6465a3f5c58a 998 LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
sunyiming 1:6465a3f5c58a 999 /* Prevent ACK for FIN to generate a sent event */
sunyiming 1:6465a3f5c58a 1000 if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
sunyiming 1:6465a3f5c58a 1001 pcb->acked--;
sunyiming 1:6465a3f5c58a 1002 }
sunyiming 1:6465a3f5c58a 1003
sunyiming 1:6465a3f5c58a 1004 pcb->snd_queuelen -= pbuf_clen(next->p);
sunyiming 1:6465a3f5c58a 1005 tcp_seg_free(next);
sunyiming 1:6465a3f5c58a 1006
sunyiming 1:6465a3f5c58a 1007 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
sunyiming 1:6465a3f5c58a 1008 if (pcb->snd_queuelen != 0) {
sunyiming 1:6465a3f5c58a 1009 LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
sunyiming 1:6465a3f5c58a 1010 pcb->unsent != NULL);
sunyiming 1:6465a3f5c58a 1011 }
sunyiming 1:6465a3f5c58a 1012 }
sunyiming 1:6465a3f5c58a 1013
sunyiming 1:6465a3f5c58a 1014 /* If there's nothing left to acknowledge, stop the retransmit
sunyiming 1:6465a3f5c58a 1015 timer, otherwise reset it to start again */
sunyiming 1:6465a3f5c58a 1016 if(pcb->unacked == NULL)
sunyiming 1:6465a3f5c58a 1017 pcb->rtime = -1;
sunyiming 1:6465a3f5c58a 1018 else
sunyiming 1:6465a3f5c58a 1019 pcb->rtime = 0;
sunyiming 1:6465a3f5c58a 1020
sunyiming 1:6465a3f5c58a 1021 pcb->polltmr = 0;
sunyiming 1:6465a3f5c58a 1022 } else {
sunyiming 1:6465a3f5c58a 1023 /* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
sunyiming 1:6465a3f5c58a 1024 pcb->acked = 0;
sunyiming 1:6465a3f5c58a 1025 }
sunyiming 1:6465a3f5c58a 1026
sunyiming 1:6465a3f5c58a 1027 /* We go through the ->unsent list to see if any of the segments
sunyiming 1:6465a3f5c58a 1028 on the list are acknowledged by the ACK. This may seem
sunyiming 1:6465a3f5c58a 1029 strange since an "unsent" segment shouldn't be acked. The
sunyiming 1:6465a3f5c58a 1030 rationale is that lwIP puts all outstanding segments on the
sunyiming 1:6465a3f5c58a 1031 ->unsent list after a retransmission, so these segments may
sunyiming 1:6465a3f5c58a 1032 in fact have been sent once. */
sunyiming 1:6465a3f5c58a 1033 while (pcb->unsent != NULL &&
sunyiming 1:6465a3f5c58a 1034 TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
sunyiming 1:6465a3f5c58a 1035 TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
sunyiming 1:6465a3f5c58a 1036 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
sunyiming 1:6465a3f5c58a 1037 ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
sunyiming 1:6465a3f5c58a 1038 TCP_TCPLEN(pcb->unsent)));
sunyiming 1:6465a3f5c58a 1039
sunyiming 1:6465a3f5c58a 1040 next = pcb->unsent;
sunyiming 1:6465a3f5c58a 1041 pcb->unsent = pcb->unsent->next;
sunyiming 1:6465a3f5c58a 1042 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
sunyiming 1:6465a3f5c58a 1043 LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
sunyiming 1:6465a3f5c58a 1044 /* Prevent ACK for FIN to generate a sent event */
sunyiming 1:6465a3f5c58a 1045 if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
sunyiming 1:6465a3f5c58a 1046 pcb->acked--;
sunyiming 1:6465a3f5c58a 1047 }
sunyiming 1:6465a3f5c58a 1048 pcb->snd_queuelen -= pbuf_clen(next->p);
sunyiming 1:6465a3f5c58a 1049 tcp_seg_free(next);
sunyiming 1:6465a3f5c58a 1050 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
sunyiming 1:6465a3f5c58a 1051 if (pcb->snd_queuelen != 0) {
sunyiming 1:6465a3f5c58a 1052 LWIP_ASSERT("tcp_receive: valid queue length",
sunyiming 1:6465a3f5c58a 1053 pcb->unacked != NULL || pcb->unsent != NULL);
sunyiming 1:6465a3f5c58a 1054 }
sunyiming 1:6465a3f5c58a 1055 }
sunyiming 1:6465a3f5c58a 1056 /* End of ACK for new data processing. */
sunyiming 1:6465a3f5c58a 1057
sunyiming 1:6465a3f5c58a 1058 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
sunyiming 1:6465a3f5c58a 1059 pcb->rttest, pcb->rtseq, ackno));
sunyiming 1:6465a3f5c58a 1060
sunyiming 1:6465a3f5c58a 1061 /* RTT estimation calculations. This is done by checking if the
sunyiming 1:6465a3f5c58a 1062 incoming segment acknowledges the segment we use to take a
sunyiming 1:6465a3f5c58a 1063 round-trip time measurement. */
sunyiming 1:6465a3f5c58a 1064 if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
sunyiming 1:6465a3f5c58a 1065 /* diff between this shouldn't exceed 32K since this are tcp timer ticks
sunyiming 1:6465a3f5c58a 1066 and a round-trip shouldn't be that long... */
sunyiming 1:6465a3f5c58a 1067 m = (s16_t)(tcp_ticks - pcb->rttest);
sunyiming 1:6465a3f5c58a 1068
sunyiming 1:6465a3f5c58a 1069 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
sunyiming 1:6465a3f5c58a 1070 m, m * TCP_SLOW_INTERVAL));
sunyiming 1:6465a3f5c58a 1071
sunyiming 1:6465a3f5c58a 1072 /* This is taken directly from VJs original code in his paper */
sunyiming 1:6465a3f5c58a 1073 m = m - (pcb->sa >> 3);
sunyiming 1:6465a3f5c58a 1074 pcb->sa += m;
sunyiming 1:6465a3f5c58a 1075 if (m < 0) {
sunyiming 1:6465a3f5c58a 1076 m = -m;
sunyiming 1:6465a3f5c58a 1077 }
sunyiming 1:6465a3f5c58a 1078 m = m - (pcb->sv >> 2);
sunyiming 1:6465a3f5c58a 1079 pcb->sv += m;
sunyiming 1:6465a3f5c58a 1080 pcb->rto = (pcb->sa >> 3) + pcb->sv;
sunyiming 1:6465a3f5c58a 1081
sunyiming 1:6465a3f5c58a 1082 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
sunyiming 1:6465a3f5c58a 1083 pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
sunyiming 1:6465a3f5c58a 1084
sunyiming 1:6465a3f5c58a 1085 pcb->rttest = 0;
sunyiming 1:6465a3f5c58a 1086 }
sunyiming 1:6465a3f5c58a 1087 }
sunyiming 1:6465a3f5c58a 1088
sunyiming 1:6465a3f5c58a 1089 /* If the incoming segment contains data, we must process it
sunyiming 1:6465a3f5c58a 1090 further. */
sunyiming 1:6465a3f5c58a 1091 if (tcplen > 0) {
sunyiming 1:6465a3f5c58a 1092 /* This code basically does three things:
sunyiming 1:6465a3f5c58a 1093
sunyiming 1:6465a3f5c58a 1094 +) If the incoming segment contains data that is the next
sunyiming 1:6465a3f5c58a 1095 in-sequence data, this data is passed to the application. This
sunyiming 1:6465a3f5c58a 1096 might involve trimming the first edge of the data. The rcv_nxt
sunyiming 1:6465a3f5c58a 1097 variable and the advertised window are adjusted.
sunyiming 1:6465a3f5c58a 1098
sunyiming 1:6465a3f5c58a 1099 +) If the incoming segment has data that is above the next
sunyiming 1:6465a3f5c58a 1100 sequence number expected (->rcv_nxt), the segment is placed on
sunyiming 1:6465a3f5c58a 1101 the ->ooseq queue. This is done by finding the appropriate
sunyiming 1:6465a3f5c58a 1102 place in the ->ooseq queue (which is ordered by sequence
sunyiming 1:6465a3f5c58a 1103 number) and trim the segment in both ends if needed. An
sunyiming 1:6465a3f5c58a 1104 immediate ACK is sent to indicate that we received an
sunyiming 1:6465a3f5c58a 1105 out-of-sequence segment.
sunyiming 1:6465a3f5c58a 1106
sunyiming 1:6465a3f5c58a 1107 +) Finally, we check if the first segment on the ->ooseq queue
sunyiming 1:6465a3f5c58a 1108 now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
sunyiming 1:6465a3f5c58a 1109 rcv_nxt > ooseq->seqno, we must trim the first edge of the
sunyiming 1:6465a3f5c58a 1110 segment on ->ooseq before we adjust rcv_nxt. The data in the
sunyiming 1:6465a3f5c58a 1111 segments that are now on sequence are chained onto the
sunyiming 1:6465a3f5c58a 1112 incoming segment so that we only need to call the application
sunyiming 1:6465a3f5c58a 1113 once.
sunyiming 1:6465a3f5c58a 1114 */
sunyiming 1:6465a3f5c58a 1115
sunyiming 1:6465a3f5c58a 1116 /* First, we check if we must trim the first edge. We have to do
sunyiming 1:6465a3f5c58a 1117 this if the sequence number of the incoming segment is less
sunyiming 1:6465a3f5c58a 1118 than rcv_nxt, and the sequence number plus the length of the
sunyiming 1:6465a3f5c58a 1119 segment is larger than rcv_nxt. */
sunyiming 1:6465a3f5c58a 1120 /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
sunyiming 1:6465a3f5c58a 1121 if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
sunyiming 1:6465a3f5c58a 1122 if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
sunyiming 1:6465a3f5c58a 1123 /* Trimming the first edge is done by pushing the payload
sunyiming 1:6465a3f5c58a 1124 pointer in the pbuf downwards. This is somewhat tricky since
sunyiming 1:6465a3f5c58a 1125 we do not want to discard the full contents of the pbuf up to
sunyiming 1:6465a3f5c58a 1126 the new starting point of the data since we have to keep the
sunyiming 1:6465a3f5c58a 1127 TCP header which is present in the first pbuf in the chain.
sunyiming 1:6465a3f5c58a 1128
sunyiming 1:6465a3f5c58a 1129 What is done is really quite a nasty hack: the first pbuf in
sunyiming 1:6465a3f5c58a 1130 the pbuf chain is pointed to by inseg.p. Since we need to be
sunyiming 1:6465a3f5c58a 1131 able to deallocate the whole pbuf, we cannot change this
sunyiming 1:6465a3f5c58a 1132 inseg.p pointer to point to any of the later pbufs in the
sunyiming 1:6465a3f5c58a 1133 chain. Instead, we point the ->payload pointer in the first
sunyiming 1:6465a3f5c58a 1134 pbuf to data in one of the later pbufs. We also set the
sunyiming 1:6465a3f5c58a 1135 inseg.data pointer to point to the right place. This way, the
sunyiming 1:6465a3f5c58a 1136 ->p pointer will still point to the first pbuf, but the
sunyiming 1:6465a3f5c58a 1137 ->p->payload pointer will point to data in another pbuf.
sunyiming 1:6465a3f5c58a 1138
sunyiming 1:6465a3f5c58a 1139 After we are done with adjusting the pbuf pointers we must
sunyiming 1:6465a3f5c58a 1140 adjust the ->data pointer in the seg and the segment
sunyiming 1:6465a3f5c58a 1141 length.*/
sunyiming 1:6465a3f5c58a 1142
sunyiming 1:6465a3f5c58a 1143 off = pcb->rcv_nxt - seqno;
sunyiming 1:6465a3f5c58a 1144 p = inseg.p;
sunyiming 1:6465a3f5c58a 1145 LWIP_ASSERT("inseg.p != NULL", inseg.p);
sunyiming 1:6465a3f5c58a 1146 LWIP_ASSERT("insane offset!", (off < 0x7fff));
sunyiming 1:6465a3f5c58a 1147 if (inseg.p->len < off) {
sunyiming 1:6465a3f5c58a 1148 LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
sunyiming 1:6465a3f5c58a 1149 new_tot_len = (u16_t)(inseg.p->tot_len - off);
sunyiming 1:6465a3f5c58a 1150 while (p->len < off) {
sunyiming 1:6465a3f5c58a 1151 off -= p->len;
sunyiming 1:6465a3f5c58a 1152 /* KJM following line changed (with addition of new_tot_len var)
sunyiming 1:6465a3f5c58a 1153 to fix bug #9076
sunyiming 1:6465a3f5c58a 1154 inseg.p->tot_len -= p->len; */
sunyiming 1:6465a3f5c58a 1155 p->tot_len = new_tot_len;
sunyiming 1:6465a3f5c58a 1156 p->len = 0;
sunyiming 1:6465a3f5c58a 1157 p = p->next;
sunyiming 1:6465a3f5c58a 1158 }
sunyiming 1:6465a3f5c58a 1159 if(pbuf_header(p, (s16_t)-off)) {
sunyiming 1:6465a3f5c58a 1160 /* Do we need to cope with this failing? Assert for now */
sunyiming 1:6465a3f5c58a 1161 LWIP_ASSERT("pbuf_header failed", 0);
sunyiming 1:6465a3f5c58a 1162 }
sunyiming 1:6465a3f5c58a 1163 } else {
sunyiming 1:6465a3f5c58a 1164 if(pbuf_header(inseg.p, (s16_t)-off)) {
sunyiming 1:6465a3f5c58a 1165 /* Do we need to cope with this failing? Assert for now */
sunyiming 1:6465a3f5c58a 1166 LWIP_ASSERT("pbuf_header failed", 0);
sunyiming 1:6465a3f5c58a 1167 }
sunyiming 1:6465a3f5c58a 1168 }
sunyiming 1:6465a3f5c58a 1169 inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
sunyiming 1:6465a3f5c58a 1170 inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
sunyiming 1:6465a3f5c58a 1171 }
sunyiming 1:6465a3f5c58a 1172 else {
sunyiming 1:6465a3f5c58a 1173 if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
sunyiming 1:6465a3f5c58a 1174 /* the whole segment is < rcv_nxt */
sunyiming 1:6465a3f5c58a 1175 /* must be a duplicate of a packet that has already been correctly handled */
sunyiming 1:6465a3f5c58a 1176
sunyiming 1:6465a3f5c58a 1177 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
sunyiming 1:6465a3f5c58a 1178 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 1179 }
sunyiming 1:6465a3f5c58a 1180 }
sunyiming 1:6465a3f5c58a 1181
sunyiming 1:6465a3f5c58a 1182 /* The sequence number must be within the window (above rcv_nxt
sunyiming 1:6465a3f5c58a 1183 and below rcv_nxt + rcv_wnd) in order to be further
sunyiming 1:6465a3f5c58a 1184 processed. */
sunyiming 1:6465a3f5c58a 1185 if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
sunyiming 1:6465a3f5c58a 1186 pcb->rcv_nxt + pcb->rcv_wnd - 1)){
sunyiming 1:6465a3f5c58a 1187 if (pcb->rcv_nxt == seqno) {
sunyiming 1:6465a3f5c58a 1188 /* The incoming segment is the next in sequence. We check if
sunyiming 1:6465a3f5c58a 1189 we have to trim the end of the segment and update rcv_nxt
sunyiming 1:6465a3f5c58a 1190 and pass the data to the application. */
sunyiming 1:6465a3f5c58a 1191 tcplen = TCP_TCPLEN(&inseg);
sunyiming 1:6465a3f5c58a 1192
sunyiming 1:6465a3f5c58a 1193 if (tcplen > pcb->rcv_wnd) {
sunyiming 1:6465a3f5c58a 1194 LWIP_DEBUGF(TCP_INPUT_DEBUG,
sunyiming 1:6465a3f5c58a 1195 ("tcp_receive: other end overran receive window"
sunyiming 1:6465a3f5c58a 1196 "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
sunyiming 1:6465a3f5c58a 1197 seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
sunyiming 1:6465a3f5c58a 1198 if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 1199 /* Must remove the FIN from the header as we're trimming
sunyiming 1:6465a3f5c58a 1200 * that byte of sequence-space from the packet */
sunyiming 1:6465a3f5c58a 1201 TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
sunyiming 1:6465a3f5c58a 1202 }
sunyiming 1:6465a3f5c58a 1203 /* Adjust length of segment to fit in the window. */
sunyiming 1:6465a3f5c58a 1204 inseg.len = pcb->rcv_wnd;
sunyiming 1:6465a3f5c58a 1205 if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
sunyiming 1:6465a3f5c58a 1206 inseg.len -= 1;
sunyiming 1:6465a3f5c58a 1207 }
sunyiming 1:6465a3f5c58a 1208 pbuf_realloc(inseg.p, inseg.len);
sunyiming 1:6465a3f5c58a 1209 tcplen = TCP_TCPLEN(&inseg);
sunyiming 1:6465a3f5c58a 1210 LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
sunyiming 1:6465a3f5c58a 1211 (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
sunyiming 1:6465a3f5c58a 1212 }
sunyiming 1:6465a3f5c58a 1213 #if TCP_QUEUE_OOSEQ
sunyiming 1:6465a3f5c58a 1214 /* Received in-sequence data, adjust ooseq data if:
sunyiming 1:6465a3f5c58a 1215 - FIN has been received or
sunyiming 1:6465a3f5c58a 1216 - inseq overlaps with ooseq */
sunyiming 1:6465a3f5c58a 1217 if (pcb->ooseq != NULL) {
sunyiming 1:6465a3f5c58a 1218 if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 1219 LWIP_DEBUGF(TCP_INPUT_DEBUG,
sunyiming 1:6465a3f5c58a 1220 ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
sunyiming 1:6465a3f5c58a 1221 /* Received in-order FIN means anything that was received
sunyiming 1:6465a3f5c58a 1222 * out of order must now have been received in-order, so
sunyiming 1:6465a3f5c58a 1223 * bin the ooseq queue */
sunyiming 1:6465a3f5c58a 1224 while (pcb->ooseq != NULL) {
sunyiming 1:6465a3f5c58a 1225 struct tcp_seg *old_ooseq = pcb->ooseq;
sunyiming 1:6465a3f5c58a 1226 pcb->ooseq = pcb->ooseq->next;
sunyiming 1:6465a3f5c58a 1227 tcp_seg_free(old_ooseq);
sunyiming 1:6465a3f5c58a 1228 }
sunyiming 1:6465a3f5c58a 1229 }
sunyiming 1:6465a3f5c58a 1230 else {
sunyiming 1:6465a3f5c58a 1231 next = pcb->ooseq;
sunyiming 1:6465a3f5c58a 1232 /* Remove all segments on ooseq that are covered by inseg already.
sunyiming 1:6465a3f5c58a 1233 * FIN is copied from ooseq to inseg if present. */
sunyiming 1:6465a3f5c58a 1234 while (next &&
sunyiming 1:6465a3f5c58a 1235 TCP_SEQ_GEQ(seqno + tcplen,
sunyiming 1:6465a3f5c58a 1236 next->tcphdr->seqno + next->len)) {
sunyiming 1:6465a3f5c58a 1237 /* inseg cannot have FIN here (already processed above) */
sunyiming 1:6465a3f5c58a 1238 if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
sunyiming 1:6465a3f5c58a 1239 (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
sunyiming 1:6465a3f5c58a 1240 TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
sunyiming 1:6465a3f5c58a 1241 tcplen = TCP_TCPLEN(&inseg);
sunyiming 1:6465a3f5c58a 1242 }
sunyiming 1:6465a3f5c58a 1243 prev = next;
sunyiming 1:6465a3f5c58a 1244 next = next->next;
sunyiming 1:6465a3f5c58a 1245 tcp_seg_free(prev);
sunyiming 1:6465a3f5c58a 1246 }
sunyiming 1:6465a3f5c58a 1247 /* Now trim right side of inseg if it overlaps with the first
sunyiming 1:6465a3f5c58a 1248 * segment on ooseq */
sunyiming 1:6465a3f5c58a 1249 if (next &&
sunyiming 1:6465a3f5c58a 1250 TCP_SEQ_GT(seqno + tcplen,
sunyiming 1:6465a3f5c58a 1251 next->tcphdr->seqno)) {
sunyiming 1:6465a3f5c58a 1252 /* inseg cannot have FIN here (already processed above) */
sunyiming 1:6465a3f5c58a 1253 inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
sunyiming 1:6465a3f5c58a 1254 if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
sunyiming 1:6465a3f5c58a 1255 inseg.len -= 1;
sunyiming 1:6465a3f5c58a 1256 }
sunyiming 1:6465a3f5c58a 1257 pbuf_realloc(inseg.p, inseg.len);
sunyiming 1:6465a3f5c58a 1258 tcplen = TCP_TCPLEN(&inseg);
sunyiming 1:6465a3f5c58a 1259 LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
sunyiming 1:6465a3f5c58a 1260 (seqno + tcplen) == next->tcphdr->seqno);
sunyiming 1:6465a3f5c58a 1261 }
sunyiming 1:6465a3f5c58a 1262 pcb->ooseq = next;
sunyiming 1:6465a3f5c58a 1263 }
sunyiming 1:6465a3f5c58a 1264 }
sunyiming 1:6465a3f5c58a 1265 #endif /* TCP_QUEUE_OOSEQ */
sunyiming 1:6465a3f5c58a 1266
sunyiming 1:6465a3f5c58a 1267 pcb->rcv_nxt = seqno + tcplen;
sunyiming 1:6465a3f5c58a 1268
sunyiming 1:6465a3f5c58a 1269 /* Update the receiver's (our) window. */
sunyiming 1:6465a3f5c58a 1270 LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
sunyiming 1:6465a3f5c58a 1271 pcb->rcv_wnd -= tcplen;
sunyiming 1:6465a3f5c58a 1272
sunyiming 1:6465a3f5c58a 1273 tcp_update_rcv_ann_wnd(pcb);
sunyiming 1:6465a3f5c58a 1274
sunyiming 1:6465a3f5c58a 1275 /* If there is data in the segment, we make preparations to
sunyiming 1:6465a3f5c58a 1276 pass this up to the application. The ->recv_data variable
sunyiming 1:6465a3f5c58a 1277 is used for holding the pbuf that goes to the
sunyiming 1:6465a3f5c58a 1278 application. The code for reassembling out-of-sequence data
sunyiming 1:6465a3f5c58a 1279 chains its data on this pbuf as well.
sunyiming 1:6465a3f5c58a 1280
sunyiming 1:6465a3f5c58a 1281 If the segment was a FIN, we set the TF_GOT_FIN flag that will
sunyiming 1:6465a3f5c58a 1282 be used to indicate to the application that the remote side has
sunyiming 1:6465a3f5c58a 1283 closed its end of the connection. */
sunyiming 1:6465a3f5c58a 1284 if (inseg.p->tot_len > 0) {
sunyiming 1:6465a3f5c58a 1285 recv_data = inseg.p;
sunyiming 1:6465a3f5c58a 1286 /* Since this pbuf now is the responsibility of the
sunyiming 1:6465a3f5c58a 1287 application, we delete our reference to it so that we won't
sunyiming 1:6465a3f5c58a 1288 (mistakingly) deallocate it. */
sunyiming 1:6465a3f5c58a 1289 inseg.p = NULL;
sunyiming 1:6465a3f5c58a 1290 }
sunyiming 1:6465a3f5c58a 1291 if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 1292 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
sunyiming 1:6465a3f5c58a 1293 recv_flags |= TF_GOT_FIN;
sunyiming 1:6465a3f5c58a 1294 }
sunyiming 1:6465a3f5c58a 1295
sunyiming 1:6465a3f5c58a 1296 #if TCP_QUEUE_OOSEQ
sunyiming 1:6465a3f5c58a 1297 /* We now check if we have segments on the ->ooseq queue that
sunyiming 1:6465a3f5c58a 1298 are now in sequence. */
sunyiming 1:6465a3f5c58a 1299 while (pcb->ooseq != NULL &&
sunyiming 1:6465a3f5c58a 1300 pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
sunyiming 1:6465a3f5c58a 1301
sunyiming 1:6465a3f5c58a 1302 cseg = pcb->ooseq;
sunyiming 1:6465a3f5c58a 1303 seqno = pcb->ooseq->tcphdr->seqno;
sunyiming 1:6465a3f5c58a 1304
sunyiming 1:6465a3f5c58a 1305 pcb->rcv_nxt += TCP_TCPLEN(cseg);
sunyiming 1:6465a3f5c58a 1306 LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
sunyiming 1:6465a3f5c58a 1307 pcb->rcv_wnd >= TCP_TCPLEN(cseg));
sunyiming 1:6465a3f5c58a 1308 pcb->rcv_wnd -= TCP_TCPLEN(cseg);
sunyiming 1:6465a3f5c58a 1309
sunyiming 1:6465a3f5c58a 1310 tcp_update_rcv_ann_wnd(pcb);
sunyiming 1:6465a3f5c58a 1311
sunyiming 1:6465a3f5c58a 1312 if (cseg->p->tot_len > 0) {
sunyiming 1:6465a3f5c58a 1313 /* Chain this pbuf onto the pbuf that we will pass to
sunyiming 1:6465a3f5c58a 1314 the application. */
sunyiming 1:6465a3f5c58a 1315 if (recv_data) {
sunyiming 1:6465a3f5c58a 1316 pbuf_cat(recv_data, cseg->p);
sunyiming 1:6465a3f5c58a 1317 } else {
sunyiming 1:6465a3f5c58a 1318 recv_data = cseg->p;
sunyiming 1:6465a3f5c58a 1319 }
sunyiming 1:6465a3f5c58a 1320 cseg->p = NULL;
sunyiming 1:6465a3f5c58a 1321 }
sunyiming 1:6465a3f5c58a 1322 if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 1323 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
sunyiming 1:6465a3f5c58a 1324 recv_flags |= TF_GOT_FIN;
sunyiming 1:6465a3f5c58a 1325 if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
sunyiming 1:6465a3f5c58a 1326 pcb->state = CLOSE_WAIT;
sunyiming 1:6465a3f5c58a 1327 }
sunyiming 1:6465a3f5c58a 1328 }
sunyiming 1:6465a3f5c58a 1329
sunyiming 1:6465a3f5c58a 1330 pcb->ooseq = cseg->next;
sunyiming 1:6465a3f5c58a 1331 tcp_seg_free(cseg);
sunyiming 1:6465a3f5c58a 1332 }
sunyiming 1:6465a3f5c58a 1333 #endif /* TCP_QUEUE_OOSEQ */
sunyiming 1:6465a3f5c58a 1334
sunyiming 1:6465a3f5c58a 1335
sunyiming 1:6465a3f5c58a 1336 /* Acknowledge the segment(s). */
sunyiming 1:6465a3f5c58a 1337 tcp_ack(pcb);
sunyiming 1:6465a3f5c58a 1338
sunyiming 1:6465a3f5c58a 1339 } else {
sunyiming 1:6465a3f5c58a 1340 /* We get here if the incoming segment is out-of-sequence. */
sunyiming 1:6465a3f5c58a 1341 tcp_send_empty_ack(pcb);
sunyiming 1:6465a3f5c58a 1342 #if TCP_QUEUE_OOSEQ
sunyiming 1:6465a3f5c58a 1343 /* We queue the segment on the ->ooseq queue. */
sunyiming 1:6465a3f5c58a 1344 if (pcb->ooseq == NULL) {
sunyiming 1:6465a3f5c58a 1345 pcb->ooseq = tcp_seg_copy(&inseg);
sunyiming 1:6465a3f5c58a 1346 } else {
sunyiming 1:6465a3f5c58a 1347 /* If the queue is not empty, we walk through the queue and
sunyiming 1:6465a3f5c58a 1348 try to find a place where the sequence number of the
sunyiming 1:6465a3f5c58a 1349 incoming segment is between the sequence numbers of the
sunyiming 1:6465a3f5c58a 1350 previous and the next segment on the ->ooseq queue. That is
sunyiming 1:6465a3f5c58a 1351 the place where we put the incoming segment. If needed, we
sunyiming 1:6465a3f5c58a 1352 trim the second edges of the previous and the incoming
sunyiming 1:6465a3f5c58a 1353 segment so that it will fit into the sequence.
sunyiming 1:6465a3f5c58a 1354
sunyiming 1:6465a3f5c58a 1355 If the incoming segment has the same sequence number as a
sunyiming 1:6465a3f5c58a 1356 segment on the ->ooseq queue, we discard the segment that
sunyiming 1:6465a3f5c58a 1357 contains less data. */
sunyiming 1:6465a3f5c58a 1358
sunyiming 1:6465a3f5c58a 1359 prev = NULL;
sunyiming 1:6465a3f5c58a 1360 for(next = pcb->ooseq; next != NULL; next = next->next) {
sunyiming 1:6465a3f5c58a 1361 if (seqno == next->tcphdr->seqno) {
sunyiming 1:6465a3f5c58a 1362 /* The sequence number of the incoming segment is the
sunyiming 1:6465a3f5c58a 1363 same as the sequence number of the segment on
sunyiming 1:6465a3f5c58a 1364 ->ooseq. We check the lengths to see which one to
sunyiming 1:6465a3f5c58a 1365 discard. */
sunyiming 1:6465a3f5c58a 1366 if (inseg.len > next->len) {
sunyiming 1:6465a3f5c58a 1367 /* The incoming segment is larger than the old
sunyiming 1:6465a3f5c58a 1368 segment. We replace some segments with the new
sunyiming 1:6465a3f5c58a 1369 one. */
sunyiming 1:6465a3f5c58a 1370 cseg = tcp_seg_copy(&inseg);
sunyiming 1:6465a3f5c58a 1371 if (cseg != NULL) {
sunyiming 1:6465a3f5c58a 1372 if (prev != NULL) {
sunyiming 1:6465a3f5c58a 1373 prev->next = cseg;
sunyiming 1:6465a3f5c58a 1374 } else {
sunyiming 1:6465a3f5c58a 1375 pcb->ooseq = cseg;
sunyiming 1:6465a3f5c58a 1376 }
sunyiming 1:6465a3f5c58a 1377 tcp_oos_insert_segment(cseg, next);
sunyiming 1:6465a3f5c58a 1378 }
sunyiming 1:6465a3f5c58a 1379 break;
sunyiming 1:6465a3f5c58a 1380 } else {
sunyiming 1:6465a3f5c58a 1381 /* Either the lenghts are the same or the incoming
sunyiming 1:6465a3f5c58a 1382 segment was smaller than the old one; in either
sunyiming 1:6465a3f5c58a 1383 case, we ditch the incoming segment. */
sunyiming 1:6465a3f5c58a 1384 break;
sunyiming 1:6465a3f5c58a 1385 }
sunyiming 1:6465a3f5c58a 1386 } else {
sunyiming 1:6465a3f5c58a 1387 if (prev == NULL) {
sunyiming 1:6465a3f5c58a 1388 if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
sunyiming 1:6465a3f5c58a 1389 /* The sequence number of the incoming segment is lower
sunyiming 1:6465a3f5c58a 1390 than the sequence number of the first segment on the
sunyiming 1:6465a3f5c58a 1391 queue. We put the incoming segment first on the
sunyiming 1:6465a3f5c58a 1392 queue. */
sunyiming 1:6465a3f5c58a 1393 cseg = tcp_seg_copy(&inseg);
sunyiming 1:6465a3f5c58a 1394 if (cseg != NULL) {
sunyiming 1:6465a3f5c58a 1395 pcb->ooseq = cseg;
sunyiming 1:6465a3f5c58a 1396 tcp_oos_insert_segment(cseg, next);
sunyiming 1:6465a3f5c58a 1397 }
sunyiming 1:6465a3f5c58a 1398 break;
sunyiming 1:6465a3f5c58a 1399 }
sunyiming 1:6465a3f5c58a 1400 } else {
sunyiming 1:6465a3f5c58a 1401 /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
sunyiming 1:6465a3f5c58a 1402 TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
sunyiming 1:6465a3f5c58a 1403 if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
sunyiming 1:6465a3f5c58a 1404 /* The sequence number of the incoming segment is in
sunyiming 1:6465a3f5c58a 1405 between the sequence numbers of the previous and
sunyiming 1:6465a3f5c58a 1406 the next segment on ->ooseq. We trim trim the previous
sunyiming 1:6465a3f5c58a 1407 segment, delete next segments that included in received segment
sunyiming 1:6465a3f5c58a 1408 and trim received, if needed. */
sunyiming 1:6465a3f5c58a 1409 cseg = tcp_seg_copy(&inseg);
sunyiming 1:6465a3f5c58a 1410 if (cseg != NULL) {
sunyiming 1:6465a3f5c58a 1411 if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
sunyiming 1:6465a3f5c58a 1412 /* We need to trim the prev segment. */
sunyiming 1:6465a3f5c58a 1413 prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
sunyiming 1:6465a3f5c58a 1414 pbuf_realloc(prev->p, prev->len);
sunyiming 1:6465a3f5c58a 1415 }
sunyiming 1:6465a3f5c58a 1416 prev->next = cseg;
sunyiming 1:6465a3f5c58a 1417 tcp_oos_insert_segment(cseg, next);
sunyiming 1:6465a3f5c58a 1418 }
sunyiming 1:6465a3f5c58a 1419 break;
sunyiming 1:6465a3f5c58a 1420 }
sunyiming 1:6465a3f5c58a 1421 }
sunyiming 1:6465a3f5c58a 1422 /* If the "next" segment is the last segment on the
sunyiming 1:6465a3f5c58a 1423 ooseq queue, we add the incoming segment to the end
sunyiming 1:6465a3f5c58a 1424 of the list. */
sunyiming 1:6465a3f5c58a 1425 if (next->next == NULL &&
sunyiming 1:6465a3f5c58a 1426 TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
sunyiming 1:6465a3f5c58a 1427 if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 1428 /* segment "next" already contains all data */
sunyiming 1:6465a3f5c58a 1429 break;
sunyiming 1:6465a3f5c58a 1430 }
sunyiming 1:6465a3f5c58a 1431 next->next = tcp_seg_copy(&inseg);
sunyiming 1:6465a3f5c58a 1432 if (next->next != NULL) {
sunyiming 1:6465a3f5c58a 1433 if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
sunyiming 1:6465a3f5c58a 1434 /* We need to trim the last segment. */
sunyiming 1:6465a3f5c58a 1435 next->len = (u16_t)(seqno - next->tcphdr->seqno);
sunyiming 1:6465a3f5c58a 1436 pbuf_realloc(next->p, next->len);
sunyiming 1:6465a3f5c58a 1437 }
sunyiming 1:6465a3f5c58a 1438 /* check if the remote side overruns our receive window */
sunyiming 1:6465a3f5c58a 1439 if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
sunyiming 1:6465a3f5c58a 1440 LWIP_DEBUGF(TCP_INPUT_DEBUG,
sunyiming 1:6465a3f5c58a 1441 ("tcp_receive: other end overran receive window"
sunyiming 1:6465a3f5c58a 1442 "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
sunyiming 1:6465a3f5c58a 1443 seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
sunyiming 1:6465a3f5c58a 1444 if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
sunyiming 1:6465a3f5c58a 1445 /* Must remove the FIN from the header as we're trimming
sunyiming 1:6465a3f5c58a 1446 * that byte of sequence-space from the packet */
sunyiming 1:6465a3f5c58a 1447 TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
sunyiming 1:6465a3f5c58a 1448 }
sunyiming 1:6465a3f5c58a 1449 /* Adjust length of segment to fit in the window. */
sunyiming 1:6465a3f5c58a 1450 next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
sunyiming 1:6465a3f5c58a 1451 pbuf_realloc(next->next->p, next->next->len);
sunyiming 1:6465a3f5c58a 1452 tcplen = TCP_TCPLEN(next->next);
sunyiming 1:6465a3f5c58a 1453 LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
sunyiming 1:6465a3f5c58a 1454 (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
sunyiming 1:6465a3f5c58a 1455 }
sunyiming 1:6465a3f5c58a 1456 }
sunyiming 1:6465a3f5c58a 1457 break;
sunyiming 1:6465a3f5c58a 1458 }
sunyiming 1:6465a3f5c58a 1459 }
sunyiming 1:6465a3f5c58a 1460 prev = next;
sunyiming 1:6465a3f5c58a 1461 }
sunyiming 1:6465a3f5c58a 1462 }
sunyiming 1:6465a3f5c58a 1463 #endif /* TCP_QUEUE_OOSEQ */
sunyiming 1:6465a3f5c58a 1464
sunyiming 1:6465a3f5c58a 1465 }
sunyiming 1:6465a3f5c58a 1466 } else {
sunyiming 1:6465a3f5c58a 1467 /* The incoming segment is not withing the window. */
sunyiming 1:6465a3f5c58a 1468 tcp_send_empty_ack(pcb);
sunyiming 1:6465a3f5c58a 1469 }
sunyiming 1:6465a3f5c58a 1470 } else {
sunyiming 1:6465a3f5c58a 1471 /* Segments with length 0 is taken care of here. Segments that
sunyiming 1:6465a3f5c58a 1472 fall out of the window are ACKed. */
sunyiming 1:6465a3f5c58a 1473 /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) ||
sunyiming 1:6465a3f5c58a 1474 TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
sunyiming 1:6465a3f5c58a 1475 if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
sunyiming 1:6465a3f5c58a 1476 tcp_ack_now(pcb);
sunyiming 1:6465a3f5c58a 1477 }
sunyiming 1:6465a3f5c58a 1478 }
sunyiming 1:6465a3f5c58a 1479 }
sunyiming 1:6465a3f5c58a 1480
sunyiming 1:6465a3f5c58a 1481 /**
sunyiming 1:6465a3f5c58a 1482 * Parses the options contained in the incoming segment.
sunyiming 1:6465a3f5c58a 1483 *
sunyiming 1:6465a3f5c58a 1484 * Called from tcp_listen_input() and tcp_process().
sunyiming 1:6465a3f5c58a 1485 * Currently, only the MSS option is supported!
sunyiming 1:6465a3f5c58a 1486 *
sunyiming 1:6465a3f5c58a 1487 * @param pcb the tcp_pcb for which a segment arrived
sunyiming 1:6465a3f5c58a 1488 */
sunyiming 1:6465a3f5c58a 1489 static void
sunyiming 1:6465a3f5c58a 1490 tcp_parseopt(struct tcp_pcb *pcb)
sunyiming 1:6465a3f5c58a 1491 {
sunyiming 1:6465a3f5c58a 1492 u16_t c, max_c;
sunyiming 1:6465a3f5c58a 1493 u16_t mss;
sunyiming 1:6465a3f5c58a 1494 u8_t *opts, opt;
sunyiming 1:6465a3f5c58a 1495 #if LWIP_TCP_TIMESTAMPS
sunyiming 1:6465a3f5c58a 1496 u32_t tsval;
sunyiming 1:6465a3f5c58a 1497 #endif
sunyiming 1:6465a3f5c58a 1498
sunyiming 1:6465a3f5c58a 1499 opts = (u8_t *)tcphdr + TCP_HLEN;
sunyiming 1:6465a3f5c58a 1500
sunyiming 1:6465a3f5c58a 1501 /* Parse the TCP MSS option, if present. */
sunyiming 1:6465a3f5c58a 1502 if(TCPH_HDRLEN(tcphdr) > 0x5) {
sunyiming 1:6465a3f5c58a 1503 max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
sunyiming 1:6465a3f5c58a 1504 for (c = 0; c < max_c; ) {
sunyiming 1:6465a3f5c58a 1505 opt = opts[c];
sunyiming 1:6465a3f5c58a 1506 switch (opt) {
sunyiming 1:6465a3f5c58a 1507 case 0x00:
sunyiming 1:6465a3f5c58a 1508 /* End of options. */
sunyiming 1:6465a3f5c58a 1509 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
sunyiming 1:6465a3f5c58a 1510 return;
sunyiming 1:6465a3f5c58a 1511 case 0x01:
sunyiming 1:6465a3f5c58a 1512 /* NOP option. */
sunyiming 1:6465a3f5c58a 1513 ++c;
sunyiming 1:6465a3f5c58a 1514 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
sunyiming 1:6465a3f5c58a 1515 break;
sunyiming 1:6465a3f5c58a 1516 case 0x02:
sunyiming 1:6465a3f5c58a 1517 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
sunyiming 1:6465a3f5c58a 1518 if (opts[c + 1] != 0x04 || c + 0x04 > max_c) {
sunyiming 1:6465a3f5c58a 1519 /* Bad length */
sunyiming 1:6465a3f5c58a 1520 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
sunyiming 1:6465a3f5c58a 1521 return;
sunyiming 1:6465a3f5c58a 1522 }
sunyiming 1:6465a3f5c58a 1523 /* An MSS option with the right option length. */
sunyiming 1:6465a3f5c58a 1524 mss = (opts[c + 2] << 8) | opts[c + 3];
sunyiming 1:6465a3f5c58a 1525 /* Limit the mss to the configured TCP_MSS and prevent division by zero */
sunyiming 1:6465a3f5c58a 1526 pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
sunyiming 1:6465a3f5c58a 1527 /* Advance to next option */
sunyiming 1:6465a3f5c58a 1528 c += 0x04;
sunyiming 1:6465a3f5c58a 1529 break;
sunyiming 1:6465a3f5c58a 1530 #if LWIP_TCP_TIMESTAMPS
sunyiming 1:6465a3f5c58a 1531 case 0x08:
sunyiming 1:6465a3f5c58a 1532 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
sunyiming 1:6465a3f5c58a 1533 if (opts[c + 1] != 0x0A || c + 0x0A > max_c) {
sunyiming 1:6465a3f5c58a 1534 /* Bad length */
sunyiming 1:6465a3f5c58a 1535 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
sunyiming 1:6465a3f5c58a 1536 return;
sunyiming 1:6465a3f5c58a 1537 }
sunyiming 1:6465a3f5c58a 1538 /* TCP timestamp option with valid length */
sunyiming 1:6465a3f5c58a 1539 tsval = (opts[c+2]) | (opts[c+3] << 8) |
sunyiming 1:6465a3f5c58a 1540 (opts[c+4] << 16) | (opts[c+5] << 24);
sunyiming 1:6465a3f5c58a 1541 if (flags & TCP_SYN) {
sunyiming 1:6465a3f5c58a 1542 pcb->ts_recent = ntohl(tsval);
sunyiming 1:6465a3f5c58a 1543 pcb->flags |= TF_TIMESTAMP;
sunyiming 1:6465a3f5c58a 1544 } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
sunyiming 1:6465a3f5c58a 1545 pcb->ts_recent = ntohl(tsval);
sunyiming 1:6465a3f5c58a 1546 }
sunyiming 1:6465a3f5c58a 1547 /* Advance to next option */
sunyiming 1:6465a3f5c58a 1548 c += 0x0A;
sunyiming 1:6465a3f5c58a 1549 break;
sunyiming 1:6465a3f5c58a 1550 #endif
sunyiming 1:6465a3f5c58a 1551 default:
sunyiming 1:6465a3f5c58a 1552 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
sunyiming 1:6465a3f5c58a 1553 if (opts[c + 1] == 0) {
sunyiming 1:6465a3f5c58a 1554 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
sunyiming 1:6465a3f5c58a 1555 /* If the length field is zero, the options are malformed
sunyiming 1:6465a3f5c58a 1556 and we don't process them further. */
sunyiming 1:6465a3f5c58a 1557 return;
sunyiming 1:6465a3f5c58a 1558 }
sunyiming 1:6465a3f5c58a 1559 /* All other options have a length field, so that we easily
sunyiming 1:6465a3f5c58a 1560 can skip past them. */
sunyiming 1:6465a3f5c58a 1561 c += opts[c + 1];
sunyiming 1:6465a3f5c58a 1562 }
sunyiming 1:6465a3f5c58a 1563 }
sunyiming 1:6465a3f5c58a 1564 }
sunyiming 1:6465a3f5c58a 1565 }
sunyiming 1:6465a3f5c58a 1566
sunyiming 1:6465a3f5c58a 1567 #endif /* LWIP_TCP */