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core/tcp_in.c@29:da6f39d13880, 2015-01-08 (annotated)

Committer:
klauss
Date:
Thu Jan 08 23:42:30 2015 +0000
Revision:
29:da6f39d13880
Parent:
0:51ac1d130fd4 
wip

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 0:51ac1d130fd4 1 /**
mbed_official 0:51ac1d130fd4 2 * @file
mbed_official 0:51ac1d130fd4 3 * Transmission Control Protocol, incoming traffic
mbed_official 0:51ac1d130fd4 4 *
mbed_official 0:51ac1d130fd4 5 * The input processing functions of the TCP layer.
mbed_official 0:51ac1d130fd4 6 *
mbed_official 0:51ac1d130fd4 7 * These functions are generally called in the order (ip_input() ->)
mbed_official 0:51ac1d130fd4 8 * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
mbed_official 0:51ac1d130fd4 9 *
mbed_official 0:51ac1d130fd4 10 */
mbed_official 0:51ac1d130fd4 11
mbed_official 0:51ac1d130fd4 12 /*
mbed_official 0:51ac1d130fd4 13 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
mbed_official 0:51ac1d130fd4 14 * All rights reserved.
mbed_official 0:51ac1d130fd4 15 *
mbed_official 0:51ac1d130fd4 16 * Redistribution and use in source and binary forms, with or without modification,
mbed_official 0:51ac1d130fd4 17 * are permitted provided that the following conditions are met:
mbed_official 0:51ac1d130fd4 18 *
mbed_official 0:51ac1d130fd4 19 * 1. Redistributions of source code must retain the above copyright notice,
mbed_official 0:51ac1d130fd4 20 * this list of conditions and the following disclaimer.
mbed_official 0:51ac1d130fd4 21 * 2. Redistributions in binary form must reproduce the above copyright notice,
mbed_official 0:51ac1d130fd4 22 * this list of conditions and the following disclaimer in the documentation
mbed_official 0:51ac1d130fd4 23 * and/or other materials provided with the distribution.
mbed_official 0:51ac1d130fd4 24 * 3. The name of the author may not be used to endorse or promote products
mbed_official 0:51ac1d130fd4 25 * derived from this software without specific prior written permission.
mbed_official 0:51ac1d130fd4 26 *
mbed_official 0:51ac1d130fd4 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
mbed_official 0:51ac1d130fd4 28 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
mbed_official 0:51ac1d130fd4 29 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
mbed_official 0:51ac1d130fd4 30 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
mbed_official 0:51ac1d130fd4 31 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
mbed_official 0:51ac1d130fd4 32 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
mbed_official 0:51ac1d130fd4 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
mbed_official 0:51ac1d130fd4 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
mbed_official 0:51ac1d130fd4 35 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
mbed_official 0:51ac1d130fd4 36 * OF SUCH DAMAGE.
mbed_official 0:51ac1d130fd4 37 *
mbed_official 0:51ac1d130fd4 38 * This file is part of the lwIP TCP/IP stack.
mbed_official 0:51ac1d130fd4 39 *
mbed_official 0:51ac1d130fd4 40 * Author: Adam Dunkels <adam@sics.se>
mbed_official 0:51ac1d130fd4 41 *
mbed_official 0:51ac1d130fd4 42 */
mbed_official 0:51ac1d130fd4 43
mbed_official 0:51ac1d130fd4 44 #include "lwip/opt.h"
mbed_official 0:51ac1d130fd4 45
mbed_official 0:51ac1d130fd4 46 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
mbed_official 0:51ac1d130fd4 47
mbed_official 0:51ac1d130fd4 48 #include "lwip/tcp_impl.h"
mbed_official 0:51ac1d130fd4 49 #include "lwip/def.h"
mbed_official 0:51ac1d130fd4 50 #include "lwip/ip_addr.h"
mbed_official 0:51ac1d130fd4 51 #include "lwip/netif.h"
mbed_official 0:51ac1d130fd4 52 #include "lwip/mem.h"
mbed_official 0:51ac1d130fd4 53 #include "lwip/memp.h"
mbed_official 0:51ac1d130fd4 54 #include "lwip/inet_chksum.h"
mbed_official 0:51ac1d130fd4 55 #include "lwip/stats.h"
mbed_official 0:51ac1d130fd4 56 #include "lwip/snmp.h"
mbed_official 0:51ac1d130fd4 57 #include "arch/perf.h"
mbed_official 0:51ac1d130fd4 58
mbed_official 0:51ac1d130fd4 59 /* These variables are global to all functions involved in the input
mbed_official 0:51ac1d130fd4 60 processing of TCP segments. They are set by the tcp_input()
mbed_official 0:51ac1d130fd4 61 function. */
mbed_official 0:51ac1d130fd4 62 static struct tcp_seg inseg;
mbed_official 0:51ac1d130fd4 63 static struct tcp_hdr *tcphdr;
mbed_official 0:51ac1d130fd4 64 static struct ip_hdr *iphdr;
mbed_official 0:51ac1d130fd4 65 static u32_t seqno, ackno;
mbed_official 0:51ac1d130fd4 66 static u8_t flags;
mbed_official 0:51ac1d130fd4 67 static u16_t tcplen;
mbed_official 0:51ac1d130fd4 68
mbed_official 0:51ac1d130fd4 69 static u8_t recv_flags;
mbed_official 0:51ac1d130fd4 70 static struct pbuf *recv_data;
mbed_official 0:51ac1d130fd4 71
mbed_official 0:51ac1d130fd4 72 struct tcp_pcb *tcp_input_pcb;
mbed_official 0:51ac1d130fd4 73
mbed_official 0:51ac1d130fd4 74 /* Forward declarations. */
mbed_official 0:51ac1d130fd4 75 static err_t tcp_process(struct tcp_pcb *pcb);
mbed_official 0:51ac1d130fd4 76 static void tcp_receive(struct tcp_pcb *pcb);
mbed_official 0:51ac1d130fd4 77 static void tcp_parseopt(struct tcp_pcb *pcb);
mbed_official 0:51ac1d130fd4 78
mbed_official 0:51ac1d130fd4 79 static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
mbed_official 0:51ac1d130fd4 80 static err_t tcp_timewait_input(struct tcp_pcb *pcb);
mbed_official 0:51ac1d130fd4 81
mbed_official 0:51ac1d130fd4 82 /**
mbed_official 0:51ac1d130fd4 83 * The initial input processing of TCP. It verifies the TCP header, demultiplexes
mbed_official 0:51ac1d130fd4 84 * the segment between the PCBs and passes it on to tcp_process(), which implements
mbed_official 0:51ac1d130fd4 85 * the TCP finite state machine. This function is called by the IP layer (in
mbed_official 0:51ac1d130fd4 86 * ip_input()).
mbed_official 0:51ac1d130fd4 87 *
mbed_official 0:51ac1d130fd4 88 * @param p received TCP segment to process (p->payload pointing to the IP header)
mbed_official 0:51ac1d130fd4 89 * @param inp network interface on which this segment was received
mbed_official 0:51ac1d130fd4 90 */
mbed_official 0:51ac1d130fd4 91 void
mbed_official 0:51ac1d130fd4 92 tcp_input(struct pbuf *p, struct netif *inp)
mbed_official 0:51ac1d130fd4 93 {
mbed_official 0:51ac1d130fd4 94 struct tcp_pcb *pcb, *prev;
mbed_official 0:51ac1d130fd4 95 struct tcp_pcb_listen *lpcb;
mbed_official 0:51ac1d130fd4 96 #if SO_REUSE
mbed_official 0:51ac1d130fd4 97 struct tcp_pcb *lpcb_prev = NULL;
mbed_official 0:51ac1d130fd4 98 struct tcp_pcb_listen *lpcb_any = NULL;
mbed_official 0:51ac1d130fd4 99 #endif /* SO_REUSE */
mbed_official 0:51ac1d130fd4 100 u8_t hdrlen;
mbed_official 0:51ac1d130fd4 101 err_t err;
mbed_official 0:51ac1d130fd4 102
mbed_official 0:51ac1d130fd4 103 PERF_START;
mbed_official 0:51ac1d130fd4 104
mbed_official 0:51ac1d130fd4 105 TCP_STATS_INC(tcp.recv);
mbed_official 0:51ac1d130fd4 106 snmp_inc_tcpinsegs();
mbed_official 0:51ac1d130fd4 107
mbed_official 0:51ac1d130fd4 108 iphdr = (struct ip_hdr *)p->payload;
mbed_official 0:51ac1d130fd4 109 tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
mbed_official 0:51ac1d130fd4 110
mbed_official 0:51ac1d130fd4 111 #if TCP_INPUT_DEBUG
mbed_official 0:51ac1d130fd4 112 tcp_debug_print(tcphdr);
mbed_official 0:51ac1d130fd4 113 #endif
mbed_official 0:51ac1d130fd4 114
mbed_official 0:51ac1d130fd4 115 /* remove header from payload */
mbed_official 0:51ac1d130fd4 116 if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
mbed_official 0:51ac1d130fd4 117 /* drop short packets */
mbed_official 0:51ac1d130fd4 118 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
mbed_official 0:51ac1d130fd4 119 TCP_STATS_INC(tcp.lenerr);
mbed_official 0:51ac1d130fd4 120 TCP_STATS_INC(tcp.drop);
mbed_official 0:51ac1d130fd4 121 snmp_inc_tcpinerrs();
mbed_official 0:51ac1d130fd4 122 pbuf_free(p);
mbed_official 0:51ac1d130fd4 123 return;
mbed_official 0:51ac1d130fd4 124 }
mbed_official 0:51ac1d130fd4 125
mbed_official 0:51ac1d130fd4 126 /* Don't even process incoming broadcasts/multicasts. */
mbed_official 0:51ac1d130fd4 127 if (ip_addr_isbroadcast(&current_iphdr_dest, inp) ||
mbed_official 0:51ac1d130fd4 128 ip_addr_ismulticast(&current_iphdr_dest)) {
mbed_official 0:51ac1d130fd4 129 TCP_STATS_INC(tcp.proterr);
mbed_official 0:51ac1d130fd4 130 TCP_STATS_INC(tcp.drop);
mbed_official 0:51ac1d130fd4 131 snmp_inc_tcpinerrs();
mbed_official 0:51ac1d130fd4 132 pbuf_free(p);
mbed_official 0:51ac1d130fd4 133 return;
mbed_official 0:51ac1d130fd4 134 }
mbed_official 0:51ac1d130fd4 135
mbed_official 0:51ac1d130fd4 136 #if CHECKSUM_CHECK_TCP
mbed_official 0:51ac1d130fd4 137 /* Verify TCP checksum. */
mbed_official 0:51ac1d130fd4 138 if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
mbed_official 0:51ac1d130fd4 139 IP_PROTO_TCP, p->tot_len) != 0) {
mbed_official 0:51ac1d130fd4 140 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
mbed_official 0:51ac1d130fd4 141 inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
mbed_official 0:51ac1d130fd4 142 IP_PROTO_TCP, p->tot_len)));
mbed_official 0:51ac1d130fd4 143 #if TCP_DEBUG
mbed_official 0:51ac1d130fd4 144 tcp_debug_print(tcphdr);
mbed_official 0:51ac1d130fd4 145 #endif /* TCP_DEBUG */
mbed_official 0:51ac1d130fd4 146 TCP_STATS_INC(tcp.chkerr);
mbed_official 0:51ac1d130fd4 147 TCP_STATS_INC(tcp.drop);
mbed_official 0:51ac1d130fd4 148 snmp_inc_tcpinerrs();
mbed_official 0:51ac1d130fd4 149 pbuf_free(p);
mbed_official 0:51ac1d130fd4 150 return;
mbed_official 0:51ac1d130fd4 151 }
mbed_official 0:51ac1d130fd4 152 #endif
mbed_official 0:51ac1d130fd4 153
mbed_official 0:51ac1d130fd4 154 /* Move the payload pointer in the pbuf so that it points to the
mbed_official 0:51ac1d130fd4 155 TCP data instead of the TCP header. */
mbed_official 0:51ac1d130fd4 156 hdrlen = TCPH_HDRLEN(tcphdr);
mbed_official 0:51ac1d130fd4 157 if(pbuf_header(p, -(hdrlen * 4))){
mbed_official 0:51ac1d130fd4 158 /* drop short packets */
mbed_official 0:51ac1d130fd4 159 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
mbed_official 0:51ac1d130fd4 160 TCP_STATS_INC(tcp.lenerr);
mbed_official 0:51ac1d130fd4 161 TCP_STATS_INC(tcp.drop);
mbed_official 0:51ac1d130fd4 162 snmp_inc_tcpinerrs();
mbed_official 0:51ac1d130fd4 163 pbuf_free(p);
mbed_official 0:51ac1d130fd4 164 return;
mbed_official 0:51ac1d130fd4 165 }
mbed_official 0:51ac1d130fd4 166
mbed_official 0:51ac1d130fd4 167 /* Convert fields in TCP header to host byte order. */
mbed_official 0:51ac1d130fd4 168 tcphdr->src = ntohs(tcphdr->src);
mbed_official 0:51ac1d130fd4 169 tcphdr->dest = ntohs(tcphdr->dest);
mbed_official 0:51ac1d130fd4 170 seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
mbed_official 0:51ac1d130fd4 171 ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
mbed_official 0:51ac1d130fd4 172 tcphdr->wnd = ntohs(tcphdr->wnd);
mbed_official 0:51ac1d130fd4 173
mbed_official 0:51ac1d130fd4 174 flags = TCPH_FLAGS(tcphdr);
mbed_official 0:51ac1d130fd4 175 tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);
mbed_official 0:51ac1d130fd4 176
mbed_official 0:51ac1d130fd4 177 /* Demultiplex an incoming segment. First, we check if it is destined
mbed_official 0:51ac1d130fd4 178 for an active connection. */
mbed_official 0:51ac1d130fd4 179 prev = NULL;
mbed_official 0:51ac1d130fd4 180
mbed_official 0:51ac1d130fd4 181
mbed_official 0:51ac1d130fd4 182 for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
mbed_official 0:51ac1d130fd4 183 LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
mbed_official 0:51ac1d130fd4 184 LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
mbed_official 0:51ac1d130fd4 185 LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
mbed_official 0:51ac1d130fd4 186 if (pcb->remote_port == tcphdr->src &&
mbed_official 0:51ac1d130fd4 187 pcb->local_port == tcphdr->dest &&
mbed_official 0:51ac1d130fd4 188 ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
mbed_official 0:51ac1d130fd4 189 ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
mbed_official 0:51ac1d130fd4 190
mbed_official 0:51ac1d130fd4 191 /* Move this PCB to the front of the list so that subsequent
mbed_official 0:51ac1d130fd4 192 lookups will be faster (we exploit locality in TCP segment
mbed_official 0:51ac1d130fd4 193 arrivals). */
mbed_official 0:51ac1d130fd4 194 LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
mbed_official 0:51ac1d130fd4 195 if (prev != NULL) {
mbed_official 0:51ac1d130fd4 196 prev->next = pcb->next;
mbed_official 0:51ac1d130fd4 197 pcb->next = tcp_active_pcbs;
mbed_official 0:51ac1d130fd4 198 tcp_active_pcbs = pcb;
mbed_official 0:51ac1d130fd4 199 }
mbed_official 0:51ac1d130fd4 200 LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
mbed_official 0:51ac1d130fd4 201 break;
mbed_official 0:51ac1d130fd4 202 }
mbed_official 0:51ac1d130fd4 203 prev = pcb;
mbed_official 0:51ac1d130fd4 204 }
mbed_official 0:51ac1d130fd4 205
mbed_official 0:51ac1d130fd4 206 if (pcb == NULL) {
mbed_official 0:51ac1d130fd4 207 /* If it did not go to an active connection, we check the connections
mbed_official 0:51ac1d130fd4 208 in the TIME-WAIT state. */
mbed_official 0:51ac1d130fd4 209 for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
mbed_official 0:51ac1d130fd4 210 LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
mbed_official 0:51ac1d130fd4 211 if (pcb->remote_port == tcphdr->src &&
mbed_official 0:51ac1d130fd4 212 pcb->local_port == tcphdr->dest &&
mbed_official 0:51ac1d130fd4 213 ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
mbed_official 0:51ac1d130fd4 214 ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
mbed_official 0:51ac1d130fd4 215 /* We don't really care enough to move this PCB to the front
mbed_official 0:51ac1d130fd4 216 of the list since we are not very likely to receive that
mbed_official 0:51ac1d130fd4 217 many segments for connections in TIME-WAIT. */
mbed_official 0:51ac1d130fd4 218 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
mbed_official 0:51ac1d130fd4 219 tcp_timewait_input(pcb);
mbed_official 0:51ac1d130fd4 220 pbuf_free(p);
mbed_official 0:51ac1d130fd4 221 return;
mbed_official 0:51ac1d130fd4 222 }
mbed_official 0:51ac1d130fd4 223 }
mbed_official 0:51ac1d130fd4 224
mbed_official 0:51ac1d130fd4 225 /* Finally, if we still did not get a match, we check all PCBs that
mbed_official 0:51ac1d130fd4 226 are LISTENing for incoming connections. */
mbed_official 0:51ac1d130fd4 227 prev = NULL;
mbed_official 0:51ac1d130fd4 228 for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
mbed_official 0:51ac1d130fd4 229 if (lpcb->local_port == tcphdr->dest) {
mbed_official 0:51ac1d130fd4 230 #if SO_REUSE
mbed_official 0:51ac1d130fd4 231 if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
mbed_official 0:51ac1d130fd4 232 /* found an exact match */
mbed_official 0:51ac1d130fd4 233 break;
mbed_official 0:51ac1d130fd4 234 } else if(ip_addr_isany(&(lpcb->local_ip))) {
mbed_official 0:51ac1d130fd4 235 /* found an ANY-match */
mbed_official 0:51ac1d130fd4 236 lpcb_any = lpcb;
mbed_official 0:51ac1d130fd4 237 lpcb_prev = prev;
mbed_official 0:51ac1d130fd4 238 }
mbed_official 0:51ac1d130fd4 239 #else /* SO_REUSE */
mbed_official 0:51ac1d130fd4 240 if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) ||
mbed_official 0:51ac1d130fd4 241 ip_addr_isany(&(lpcb->local_ip))) {
mbed_official 0:51ac1d130fd4 242 /* found a match */
mbed_official 0:51ac1d130fd4 243 break;
mbed_official 0:51ac1d130fd4 244 }
mbed_official 0:51ac1d130fd4 245 #endif /* SO_REUSE */
mbed_official 0:51ac1d130fd4 246 }
mbed_official 0:51ac1d130fd4 247 prev = (struct tcp_pcb *)lpcb;
mbed_official 0:51ac1d130fd4 248 }
mbed_official 0:51ac1d130fd4 249 #if SO_REUSE
mbed_official 0:51ac1d130fd4 250 /* first try specific local IP */
mbed_official 0:51ac1d130fd4 251 if (lpcb == NULL) {
mbed_official 0:51ac1d130fd4 252 /* only pass to ANY if no specific local IP has been found */
mbed_official 0:51ac1d130fd4 253 lpcb = lpcb_any;
mbed_official 0:51ac1d130fd4 254 prev = lpcb_prev;
mbed_official 0:51ac1d130fd4 255 }
mbed_official 0:51ac1d130fd4 256 #endif /* SO_REUSE */
mbed_official 0:51ac1d130fd4 257 if (lpcb != NULL) {
mbed_official 0:51ac1d130fd4 258 /* Move this PCB to the front of the list so that subsequent
mbed_official 0:51ac1d130fd4 259 lookups will be faster (we exploit locality in TCP segment
mbed_official 0:51ac1d130fd4 260 arrivals). */
mbed_official 0:51ac1d130fd4 261 if (prev != NULL) {
mbed_official 0:51ac1d130fd4 262 ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
mbed_official 0:51ac1d130fd4 263 /* our successor is the remainder of the listening list */
mbed_official 0:51ac1d130fd4 264 lpcb->next = tcp_listen_pcbs.listen_pcbs;
mbed_official 0:51ac1d130fd4 265 /* put this listening pcb at the head of the listening list */
mbed_official 0:51ac1d130fd4 266 tcp_listen_pcbs.listen_pcbs = lpcb;
mbed_official 0:51ac1d130fd4 267 }
mbed_official 0:51ac1d130fd4 268
mbed_official 0:51ac1d130fd4 269 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
mbed_official 0:51ac1d130fd4 270 tcp_listen_input(lpcb);
mbed_official 0:51ac1d130fd4 271 pbuf_free(p);
mbed_official 0:51ac1d130fd4 272 return;
mbed_official 0:51ac1d130fd4 273 }
mbed_official 0:51ac1d130fd4 274 }
mbed_official 0:51ac1d130fd4 275
mbed_official 0:51ac1d130fd4 276 #if TCP_INPUT_DEBUG
mbed_official 0:51ac1d130fd4 277 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
mbed_official 0:51ac1d130fd4 278 tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
mbed_official 0:51ac1d130fd4 279 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
mbed_official 0:51ac1d130fd4 280 #endif /* TCP_INPUT_DEBUG */
mbed_official 0:51ac1d130fd4 281
mbed_official 0:51ac1d130fd4 282
mbed_official 0:51ac1d130fd4 283 if (pcb != NULL) {
mbed_official 0:51ac1d130fd4 284 /* The incoming segment belongs to a connection. */
mbed_official 0:51ac1d130fd4 285 #if TCP_INPUT_DEBUG
mbed_official 0:51ac1d130fd4 286 #if TCP_DEBUG
mbed_official 0:51ac1d130fd4 287 tcp_debug_print_state(pcb->state);
mbed_official 0:51ac1d130fd4 288 #endif /* TCP_DEBUG */
mbed_official 0:51ac1d130fd4 289 #endif /* TCP_INPUT_DEBUG */
mbed_official 0:51ac1d130fd4 290
mbed_official 0:51ac1d130fd4 291 /* Set up a tcp_seg structure. */
mbed_official 0:51ac1d130fd4 292 inseg.next = NULL;
mbed_official 0:51ac1d130fd4 293 inseg.len = p->tot_len;
mbed_official 0:51ac1d130fd4 294 inseg.p = p;
mbed_official 0:51ac1d130fd4 295 inseg.tcphdr = tcphdr;
mbed_official 0:51ac1d130fd4 296
mbed_official 0:51ac1d130fd4 297 recv_data = NULL;
mbed_official 0:51ac1d130fd4 298 recv_flags = 0;
mbed_official 0:51ac1d130fd4 299
mbed_official 0:51ac1d130fd4 300 /* If there is data which was previously "refused" by upper layer */
mbed_official 0:51ac1d130fd4 301 if (pcb->refused_data != NULL) {
mbed_official 0:51ac1d130fd4 302 /* Notify again application with data previously received. */
mbed_official 0:51ac1d130fd4 303 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
mbed_official 0:51ac1d130fd4 304 TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
mbed_official 0:51ac1d130fd4 305 if (err == ERR_OK) {
mbed_official 0:51ac1d130fd4 306 pcb->refused_data = NULL;
mbed_official 0:51ac1d130fd4 307 } else if ((err == ERR_ABRT) || (tcplen > 0)) {
mbed_official 0:51ac1d130fd4 308 /* if err == ERR_ABRT, 'pcb' is already deallocated */
mbed_official 0:51ac1d130fd4 309 /* Drop incoming packets because pcb is "full" (only if the incoming
mbed_official 0:51ac1d130fd4 310 segment contains data). */
mbed_official 0:51ac1d130fd4 311 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
mbed_official 0:51ac1d130fd4 312 TCP_STATS_INC(tcp.drop);
mbed_official 0:51ac1d130fd4 313 snmp_inc_tcpinerrs();
mbed_official 0:51ac1d130fd4 314 pbuf_free(p);
mbed_official 0:51ac1d130fd4 315 return;
mbed_official 0:51ac1d130fd4 316 }
mbed_official 0:51ac1d130fd4 317 }
mbed_official 0:51ac1d130fd4 318 tcp_input_pcb = pcb;
mbed_official 0:51ac1d130fd4 319 err = tcp_process(pcb);
mbed_official 0:51ac1d130fd4 320 /* A return value of ERR_ABRT means that tcp_abort() was called
mbed_official 0:51ac1d130fd4 321 and that the pcb has been freed. If so, we don't do anything. */
mbed_official 0:51ac1d130fd4 322 if (err != ERR_ABRT) {
mbed_official 0:51ac1d130fd4 323 if (recv_flags & TF_RESET) {
mbed_official 0:51ac1d130fd4 324 /* TF_RESET means that the connection was reset by the other
mbed_official 0:51ac1d130fd4 325 end. We then call the error callback to inform the
mbed_official 0:51ac1d130fd4 326 application that the connection is dead before we
mbed_official 0:51ac1d130fd4 327 deallocate the PCB. */
mbed_official 0:51ac1d130fd4 328 TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
mbed_official 0:51ac1d130fd4 329 tcp_pcb_remove(&tcp_active_pcbs, pcb);
mbed_official 0:51ac1d130fd4 330 memp_free(MEMP_TCP_PCB, pcb);
mbed_official 0:51ac1d130fd4 331 } else if (recv_flags & TF_CLOSED) {
mbed_official 0:51ac1d130fd4 332 /* The connection has been closed and we will deallocate the
mbed_official 0:51ac1d130fd4 333 PCB. */
mbed_official 0:51ac1d130fd4 334 tcp_pcb_remove(&tcp_active_pcbs, pcb);
mbed_official 0:51ac1d130fd4 335 memp_free(MEMP_TCP_PCB, pcb);
mbed_official 0:51ac1d130fd4 336 } else {
mbed_official 0:51ac1d130fd4 337 err = ERR_OK;
mbed_official 0:51ac1d130fd4 338 /* If the application has registered a "sent" function to be
mbed_official 0:51ac1d130fd4 339 called when new send buffer space is available, we call it
mbed_official 0:51ac1d130fd4 340 now. */
mbed_official 0:51ac1d130fd4 341 if (pcb->acked > 0) {
mbed_official 0:51ac1d130fd4 342 TCP_EVENT_SENT(pcb, pcb->acked, err);
mbed_official 0:51ac1d130fd4 343 if (err == ERR_ABRT) {
mbed_official 0:51ac1d130fd4 344 goto aborted;
mbed_official 0:51ac1d130fd4 345 }
mbed_official 0:51ac1d130fd4 346 }
mbed_official 0:51ac1d130fd4 347
mbed_official 0:51ac1d130fd4 348 if (recv_data != NULL) {
mbed_official 0:51ac1d130fd4 349 LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
mbed_official 0:51ac1d130fd4 350 if (pcb->flags & TF_RXCLOSED) {
mbed_official 0:51ac1d130fd4 351 /* received data although already closed -> abort (send RST) to
mbed_official 0:51ac1d130fd4 352 notify the remote host that not all data has been processed */
mbed_official 0:51ac1d130fd4 353 pbuf_free(recv_data);
mbed_official 0:51ac1d130fd4 354 tcp_abort(pcb);
mbed_official 0:51ac1d130fd4 355 goto aborted;
mbed_official 0:51ac1d130fd4 356 }
mbed_official 0:51ac1d130fd4 357 if (flags & TCP_PSH) {
mbed_official 0:51ac1d130fd4 358 recv_data->flags |= PBUF_FLAG_PUSH;
mbed_official 0:51ac1d130fd4 359 }
mbed_official 0:51ac1d130fd4 360
mbed_official 0:51ac1d130fd4 361 /* Notify application that data has been received. */
mbed_official 0:51ac1d130fd4 362 TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
mbed_official 0:51ac1d130fd4 363 if (err == ERR_ABRT) {
mbed_official 0:51ac1d130fd4 364 goto aborted;
mbed_official 0:51ac1d130fd4 365 }
mbed_official 0:51ac1d130fd4 366
mbed_official 0:51ac1d130fd4 367 /* If the upper layer can't receive this data, store it */
mbed_official 0:51ac1d130fd4 368 if (err != ERR_OK) {
mbed_official 0:51ac1d130fd4 369 pcb->refused_data = recv_data;
mbed_official 0:51ac1d130fd4 370 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
mbed_official 0:51ac1d130fd4 371 }
mbed_official 0:51ac1d130fd4 372 }
mbed_official 0:51ac1d130fd4 373
mbed_official 0:51ac1d130fd4 374 /* If a FIN segment was received, we call the callback
mbed_official 0:51ac1d130fd4 375 function with a NULL buffer to indicate EOF. */
mbed_official 0:51ac1d130fd4 376 if (recv_flags & TF_GOT_FIN) {
mbed_official 0:51ac1d130fd4 377 /* correct rcv_wnd as the application won't call tcp_recved()
mbed_official 0:51ac1d130fd4 378 for the FIN's seqno */
mbed_official 0:51ac1d130fd4 379 if (pcb->rcv_wnd != TCP_WND) {
mbed_official 0:51ac1d130fd4 380 pcb->rcv_wnd++;
mbed_official 0:51ac1d130fd4 381 }
mbed_official 0:51ac1d130fd4 382 TCP_EVENT_CLOSED(pcb, err);
mbed_official 0:51ac1d130fd4 383 if (err == ERR_ABRT) {
mbed_official 0:51ac1d130fd4 384 goto aborted;
mbed_official 0:51ac1d130fd4 385 }
mbed_official 0:51ac1d130fd4 386 }
mbed_official 0:51ac1d130fd4 387
mbed_official 0:51ac1d130fd4 388 tcp_input_pcb = NULL;
mbed_official 0:51ac1d130fd4 389 /* Try to send something out. */
mbed_official 0:51ac1d130fd4 390 tcp_output(pcb);
mbed_official 0:51ac1d130fd4 391 #if TCP_INPUT_DEBUG
mbed_official 0:51ac1d130fd4 392 #if TCP_DEBUG
mbed_official 0:51ac1d130fd4 393 tcp_debug_print_state(pcb->state);
mbed_official 0:51ac1d130fd4 394 #endif /* TCP_DEBUG */
mbed_official 0:51ac1d130fd4 395 #endif /* TCP_INPUT_DEBUG */
mbed_official 0:51ac1d130fd4 396 }
mbed_official 0:51ac1d130fd4 397 }
mbed_official 0:51ac1d130fd4 398 /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
mbed_official 0:51ac1d130fd4 399 Below this line, 'pcb' may not be dereferenced! */
mbed_official 0:51ac1d130fd4 400 aborted:
mbed_official 0:51ac1d130fd4 401 tcp_input_pcb = NULL;
mbed_official 0:51ac1d130fd4 402 recv_data = NULL;
mbed_official 0:51ac1d130fd4 403
mbed_official 0:51ac1d130fd4 404 /* give up our reference to inseg.p */
mbed_official 0:51ac1d130fd4 405 if (inseg.p != NULL)
mbed_official 0:51ac1d130fd4 406 {
mbed_official 0:51ac1d130fd4 407 pbuf_free(inseg.p);
mbed_official 0:51ac1d130fd4 408 inseg.p = NULL;
mbed_official 0:51ac1d130fd4 409 }
mbed_official 0:51ac1d130fd4 410 } else {
mbed_official 0:51ac1d130fd4 411
mbed_official 0:51ac1d130fd4 412 /* If no matching PCB was found, send a TCP RST (reset) to the
mbed_official 0:51ac1d130fd4 413 sender. */
mbed_official 0:51ac1d130fd4 414 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
mbed_official 0:51ac1d130fd4 415 if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
mbed_official 0:51ac1d130fd4 416 TCP_STATS_INC(tcp.proterr);
mbed_official 0:51ac1d130fd4 417 TCP_STATS_INC(tcp.drop);
mbed_official 0:51ac1d130fd4 418 tcp_rst(ackno, seqno + tcplen,
mbed_official 0:51ac1d130fd4 419 ip_current_dest_addr(), ip_current_src_addr(),
mbed_official 0:51ac1d130fd4 420 tcphdr->dest, tcphdr->src);
mbed_official 0:51ac1d130fd4 421 }
mbed_official 0:51ac1d130fd4 422 pbuf_free(p);
mbed_official 0:51ac1d130fd4 423 }
mbed_official 0:51ac1d130fd4 424
mbed_official 0:51ac1d130fd4 425 LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
mbed_official 0:51ac1d130fd4 426 PERF_STOP("tcp_input");
mbed_official 0:51ac1d130fd4 427 }
mbed_official 0:51ac1d130fd4 428
mbed_official 0:51ac1d130fd4 429 /**
mbed_official 0:51ac1d130fd4 430 * Called by tcp_input() when a segment arrives for a listening
mbed_official 0:51ac1d130fd4 431 * connection (from tcp_input()).
mbed_official 0:51ac1d130fd4 432 *
mbed_official 0:51ac1d130fd4 433 * @param pcb the tcp_pcb_listen for which a segment arrived
mbed_official 0:51ac1d130fd4 434 * @return ERR_OK if the segment was processed
mbed_official 0:51ac1d130fd4 435 * another err_t on error
mbed_official 0:51ac1d130fd4 436 *
mbed_official 0:51ac1d130fd4 437 * @note the return value is not (yet?) used in tcp_input()
mbed_official 0:51ac1d130fd4 438 * @note the segment which arrived is saved in global variables, therefore only the pcb
mbed_official 0:51ac1d130fd4 439 * involved is passed as a parameter to this function
mbed_official 0:51ac1d130fd4 440 */
mbed_official 0:51ac1d130fd4 441 static err_t
mbed_official 0:51ac1d130fd4 442 tcp_listen_input(struct tcp_pcb_listen *pcb)
mbed_official 0:51ac1d130fd4 443 {
mbed_official 0:51ac1d130fd4 444 struct tcp_pcb *npcb;
mbed_official 0:51ac1d130fd4 445 err_t rc;
mbed_official 0:51ac1d130fd4 446
mbed_official 0:51ac1d130fd4 447 /* In the LISTEN state, we check for incoming SYN segments,
mbed_official 0:51ac1d130fd4 448 creates a new PCB, and responds with a SYN|ACK. */
mbed_official 0:51ac1d130fd4 449 if (flags & TCP_ACK) {
mbed_official 0:51ac1d130fd4 450 /* For incoming segments with the ACK flag set, respond with a
mbed_official 0:51ac1d130fd4 451 RST. */
mbed_official 0:51ac1d130fd4 452 LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
mbed_official 0:51ac1d130fd4 453 tcp_rst(ackno + 1, seqno + tcplen,
mbed_official 0:51ac1d130fd4 454 ip_current_dest_addr(), ip_current_src_addr(),
mbed_official 0:51ac1d130fd4 455 tcphdr->dest, tcphdr->src);
mbed_official 0:51ac1d130fd4 456 } else if (flags & TCP_SYN) {
mbed_official 0:51ac1d130fd4 457 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
mbed_official 0:51ac1d130fd4 458 #if TCP_LISTEN_BACKLOG
mbed_official 0:51ac1d130fd4 459 if (pcb->accepts_pending >= pcb->backlog) {
mbed_official 0:51ac1d130fd4 460 LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
mbed_official 0:51ac1d130fd4 461 return ERR_ABRT;
mbed_official 0:51ac1d130fd4 462 }
mbed_official 0:51ac1d130fd4 463 #endif /* TCP_LISTEN_BACKLOG */
mbed_official 0:51ac1d130fd4 464 npcb = tcp_alloc(pcb->prio);
mbed_official 0:51ac1d130fd4 465 /* If a new PCB could not be created (probably due to lack of memory),
mbed_official 0:51ac1d130fd4 466 we don't do anything, but rely on the sender will retransmit the
mbed_official 0:51ac1d130fd4 467 SYN at a time when we have more memory available. */
mbed_official 0:51ac1d130fd4 468 if (npcb == NULL) {
mbed_official 0:51ac1d130fd4 469 LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
mbed_official 0:51ac1d130fd4 470 TCP_STATS_INC(tcp.memerr);
mbed_official 0:51ac1d130fd4 471 return ERR_MEM;
mbed_official 0:51ac1d130fd4 472 }
mbed_official 0:51ac1d130fd4 473 #if TCP_LISTEN_BACKLOG
mbed_official 0:51ac1d130fd4 474 pcb->accepts_pending++;
mbed_official 0:51ac1d130fd4 475 #endif /* TCP_LISTEN_BACKLOG */
mbed_official 0:51ac1d130fd4 476 /* Set up the new PCB. */
mbed_official 0:51ac1d130fd4 477 ip_addr_copy(npcb->local_ip, current_iphdr_dest);
mbed_official 0:51ac1d130fd4 478 npcb->local_port = pcb->local_port;
mbed_official 0:51ac1d130fd4 479 ip_addr_copy(npcb->remote_ip, current_iphdr_src);
mbed_official 0:51ac1d130fd4 480 npcb->remote_port = tcphdr->src;
mbed_official 0:51ac1d130fd4 481 npcb->state = SYN_RCVD;
mbed_official 0:51ac1d130fd4 482 npcb->rcv_nxt = seqno + 1;
mbed_official 0:51ac1d130fd4 483 npcb->rcv_ann_right_edge = npcb->rcv_nxt;
mbed_official 0:51ac1d130fd4 484 npcb->snd_wnd = tcphdr->wnd;
mbed_official 0:51ac1d130fd4 485 npcb->ssthresh = npcb->snd_wnd;
mbed_official 0:51ac1d130fd4 486 npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
mbed_official 0:51ac1d130fd4 487 npcb->callback_arg = pcb->callback_arg;
mbed_official 0:51ac1d130fd4 488 #if LWIP_CALLBACK_API
mbed_official 0:51ac1d130fd4 489 npcb->accept = pcb->accept;
mbed_official 0:51ac1d130fd4 490 #endif /* LWIP_CALLBACK_API */
mbed_official 0:51ac1d130fd4 491 /* inherit socket options */
mbed_official 0:51ac1d130fd4 492 npcb->so_options = pcb->so_options & SOF_INHERITED;
mbed_official 0:51ac1d130fd4 493 /* Register the new PCB so that we can begin receiving segments
mbed_official 0:51ac1d130fd4 494 for it. */
mbed_official 0:51ac1d130fd4 495 TCP_REG(&tcp_active_pcbs, npcb);
mbed_official 0:51ac1d130fd4 496
mbed_official 0:51ac1d130fd4 497 /* Parse any options in the SYN. */
mbed_official 0:51ac1d130fd4 498 tcp_parseopt(npcb);
mbed_official 0:51ac1d130fd4 499 #if TCP_CALCULATE_EFF_SEND_MSS
mbed_official 0:51ac1d130fd4 500 npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
mbed_official 0:51ac1d130fd4 501 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
mbed_official 0:51ac1d130fd4 502
mbed_official 0:51ac1d130fd4 503 snmp_inc_tcppassiveopens();
mbed_official 0:51ac1d130fd4 504
mbed_official 0:51ac1d130fd4 505 /* Send a SYN|ACK together with the MSS option. */
mbed_official 0:51ac1d130fd4 506 rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
mbed_official 0:51ac1d130fd4 507 if (rc != ERR_OK) {
mbed_official 0:51ac1d130fd4 508 tcp_abandon(npcb, 0);
mbed_official 0:51ac1d130fd4 509 return rc;
mbed_official 0:51ac1d130fd4 510 }
mbed_official 0:51ac1d130fd4 511 return tcp_output(npcb);
mbed_official 0:51ac1d130fd4 512 }
mbed_official 0:51ac1d130fd4 513 return ERR_OK;
mbed_official 0:51ac1d130fd4 514 }
mbed_official 0:51ac1d130fd4 515
mbed_official 0:51ac1d130fd4 516 /**
mbed_official 0:51ac1d130fd4 517 * Called by tcp_input() when a segment arrives for a connection in
mbed_official 0:51ac1d130fd4 518 * TIME_WAIT.
mbed_official 0:51ac1d130fd4 519 *
mbed_official 0:51ac1d130fd4 520 * @param pcb the tcp_pcb for which a segment arrived
mbed_official 0:51ac1d130fd4 521 *
mbed_official 0:51ac1d130fd4 522 * @note the segment which arrived is saved in global variables, therefore only the pcb
mbed_official 0:51ac1d130fd4 523 * involved is passed as a parameter to this function
mbed_official 0:51ac1d130fd4 524 */
mbed_official 0:51ac1d130fd4 525 static err_t
mbed_official 0:51ac1d130fd4 526 tcp_timewait_input(struct tcp_pcb *pcb)
mbed_official 0:51ac1d130fd4 527 {
mbed_official 0:51ac1d130fd4 528 /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
mbed_official 0:51ac1d130fd4 529 /* RFC 793 3.9 Event Processing - Segment Arrives:
mbed_official 0:51ac1d130fd4 530 * - first check sequence number - we skip that one in TIME_WAIT (always
mbed_official 0:51ac1d130fd4 531 * acceptable since we only send ACKs)
mbed_official 0:51ac1d130fd4 532 * - second check the RST bit (... return) */
mbed_official 0:51ac1d130fd4 533 if (flags & TCP_RST) {
mbed_official 0:51ac1d130fd4 534 return ERR_OK;
mbed_official 0:51ac1d130fd4 535 }
mbed_official 0:51ac1d130fd4 536 /* - fourth, check the SYN bit, */
mbed_official 0:51ac1d130fd4 537 if (flags & TCP_SYN) {
mbed_official 0:51ac1d130fd4 538 /* If an incoming segment is not acceptable, an acknowledgment
mbed_official 0:51ac1d130fd4 539 should be sent in reply */
mbed_official 0:51ac1d130fd4 540 if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
mbed_official 0:51ac1d130fd4 541 /* If the SYN is in the window it is an error, send a reset */
mbed_official 0:51ac1d130fd4 542 tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
mbed_official 0:51ac1d130fd4 543 tcphdr->dest, tcphdr->src);
mbed_official 0:51ac1d130fd4 544 return ERR_OK;
mbed_official 0:51ac1d130fd4 545 }
mbed_official 0:51ac1d130fd4 546 } else if (flags & TCP_FIN) {
mbed_official 0:51ac1d130fd4 547 /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
mbed_official 0:51ac1d130fd4 548 Restart the 2 MSL time-wait timeout.*/
mbed_official 0:51ac1d130fd4 549 pcb->tmr = tcp_ticks;
mbed_official 0:51ac1d130fd4 550 }
mbed_official 0:51ac1d130fd4 551
mbed_official 0:51ac1d130fd4 552 if ((tcplen > 0)) {
mbed_official 0:51ac1d130fd4 553 /* Acknowledge data, FIN or out-of-window SYN */
mbed_official 0:51ac1d130fd4 554 pcb->flags |= TF_ACK_NOW;
mbed_official 0:51ac1d130fd4 555 return tcp_output(pcb);
mbed_official 0:51ac1d130fd4 556 }
mbed_official 0:51ac1d130fd4 557 return ERR_OK;
mbed_official 0:51ac1d130fd4 558 }
mbed_official 0:51ac1d130fd4 559
mbed_official 0:51ac1d130fd4 560 /**
mbed_official 0:51ac1d130fd4 561 * Implements the TCP state machine. Called by tcp_input. In some
mbed_official 0:51ac1d130fd4 562 * states tcp_receive() is called to receive data. The tcp_seg
mbed_official 0:51ac1d130fd4 563 * argument will be freed by the caller (tcp_input()) unless the
mbed_official 0:51ac1d130fd4 564 * recv_data pointer in the pcb is set.
mbed_official 0:51ac1d130fd4 565 *
mbed_official 0:51ac1d130fd4 566 * @param pcb the tcp_pcb for which a segment arrived
mbed_official 0:51ac1d130fd4 567 *
mbed_official 0:51ac1d130fd4 568 * @note the segment which arrived is saved in global variables, therefore only the pcb
mbed_official 0:51ac1d130fd4 569 * involved is passed as a parameter to this function
mbed_official 0:51ac1d130fd4 570 */
mbed_official 0:51ac1d130fd4 571 static err_t
mbed_official 0:51ac1d130fd4 572 tcp_process(struct tcp_pcb *pcb)
mbed_official 0:51ac1d130fd4 573 {
mbed_official 0:51ac1d130fd4 574 struct tcp_seg *rseg;
mbed_official 0:51ac1d130fd4 575 u8_t acceptable = 0;
mbed_official 0:51ac1d130fd4 576 err_t err;
mbed_official 0:51ac1d130fd4 577
mbed_official 0:51ac1d130fd4 578 err = ERR_OK;
mbed_official 0:51ac1d130fd4 579
mbed_official 0:51ac1d130fd4 580 /* Process incoming RST segments. */
mbed_official 0:51ac1d130fd4 581 if (flags & TCP_RST) {
mbed_official 0:51ac1d130fd4 582 /* First, determine if the reset is acceptable. */
mbed_official 0:51ac1d130fd4 583 if (pcb->state == SYN_SENT) {
mbed_official 0:51ac1d130fd4 584 if (ackno == pcb->snd_nxt) {
mbed_official 0:51ac1d130fd4 585 acceptable = 1;
mbed_official 0:51ac1d130fd4 586 }
mbed_official 0:51ac1d130fd4 587 } else {
mbed_official 0:51ac1d130fd4 588 if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
mbed_official 0:51ac1d130fd4 589 pcb->rcv_nxt+pcb->rcv_wnd)) {
mbed_official 0:51ac1d130fd4 590 acceptable = 1;
mbed_official 0:51ac1d130fd4 591 }
mbed_official 0:51ac1d130fd4 592 }
mbed_official 0:51ac1d130fd4 593
mbed_official 0:51ac1d130fd4 594 if (acceptable) {
mbed_official 0:51ac1d130fd4 595 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
mbed_official 0:51ac1d130fd4 596 LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
mbed_official 0:51ac1d130fd4 597 recv_flags |= TF_RESET;
mbed_official 0:51ac1d130fd4 598 pcb->flags &= ~TF_ACK_DELAY;
mbed_official 0:51ac1d130fd4 599 return ERR_RST;
mbed_official 0:51ac1d130fd4 600 } else {
mbed_official 0:51ac1d130fd4 601 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
mbed_official 0:51ac1d130fd4 602 seqno, pcb->rcv_nxt));
mbed_official 0:51ac1d130fd4 603 LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
mbed_official 0:51ac1d130fd4 604 seqno, pcb->rcv_nxt));
mbed_official 0:51ac1d130fd4 605 return ERR_OK;
mbed_official 0:51ac1d130fd4 606 }
mbed_official 0:51ac1d130fd4 607 }
mbed_official 0:51ac1d130fd4 608
mbed_official 0:51ac1d130fd4 609 if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
mbed_official 0:51ac1d130fd4 610 /* Cope with new connection attempt after remote end crashed */
mbed_official 0:51ac1d130fd4 611 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 612 return ERR_OK;
mbed_official 0:51ac1d130fd4 613 }
mbed_official 0:51ac1d130fd4 614
mbed_official 0:51ac1d130fd4 615 if ((pcb->flags & TF_RXCLOSED) == 0) {
mbed_official 0:51ac1d130fd4 616 /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
mbed_official 0:51ac1d130fd4 617 pcb->tmr = tcp_ticks;
mbed_official 0:51ac1d130fd4 618 }
mbed_official 0:51ac1d130fd4 619 pcb->keep_cnt_sent = 0;
mbed_official 0:51ac1d130fd4 620
mbed_official 0:51ac1d130fd4 621 tcp_parseopt(pcb);
mbed_official 0:51ac1d130fd4 622
mbed_official 0:51ac1d130fd4 623 /* Do different things depending on the TCP state. */
mbed_official 0:51ac1d130fd4 624 switch (pcb->state) {
mbed_official 0:51ac1d130fd4 625 case SYN_SENT:
mbed_official 0:51ac1d130fd4 626 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
mbed_official 0:51ac1d130fd4 627 pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
mbed_official 0:51ac1d130fd4 628 /* received SYN ACK with expected sequence number? */
mbed_official 0:51ac1d130fd4 629 if ((flags & TCP_ACK) && (flags & TCP_SYN)
mbed_official 0:51ac1d130fd4 630 && ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
mbed_official 0:51ac1d130fd4 631 pcb->snd_buf++;
mbed_official 0:51ac1d130fd4 632 pcb->rcv_nxt = seqno + 1;
mbed_official 0:51ac1d130fd4 633 pcb->rcv_ann_right_edge = pcb->rcv_nxt;
mbed_official 0:51ac1d130fd4 634 pcb->lastack = ackno;
mbed_official 0:51ac1d130fd4 635 pcb->snd_wnd = tcphdr->wnd;
mbed_official 0:51ac1d130fd4 636 pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
mbed_official 0:51ac1d130fd4 637 pcb->state = ESTABLISHED;
mbed_official 0:51ac1d130fd4 638
mbed_official 0:51ac1d130fd4 639 #if TCP_CALCULATE_EFF_SEND_MSS
mbed_official 0:51ac1d130fd4 640 pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
mbed_official 0:51ac1d130fd4 641 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
mbed_official 0:51ac1d130fd4 642
mbed_official 0:51ac1d130fd4 643 /* Set ssthresh again after changing pcb->mss (already set in tcp_connect
mbed_official 0:51ac1d130fd4 644 * but for the default value of pcb->mss) */
mbed_official 0:51ac1d130fd4 645 pcb->ssthresh = pcb->mss * 10;
mbed_official 0:51ac1d130fd4 646
mbed_official 0:51ac1d130fd4 647 pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
mbed_official 0:51ac1d130fd4 648 LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
mbed_official 0:51ac1d130fd4 649 --pcb->snd_queuelen;
mbed_official 0:51ac1d130fd4 650 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
mbed_official 0:51ac1d130fd4 651 rseg = pcb->unacked;
mbed_official 0:51ac1d130fd4 652 pcb->unacked = rseg->next;
mbed_official 0:51ac1d130fd4 653
mbed_official 0:51ac1d130fd4 654 /* If there's nothing left to acknowledge, stop the retransmit
mbed_official 0:51ac1d130fd4 655 timer, otherwise reset it to start again */
mbed_official 0:51ac1d130fd4 656 if(pcb->unacked == NULL)
mbed_official 0:51ac1d130fd4 657 pcb->rtime = -1;
mbed_official 0:51ac1d130fd4 658 else {
mbed_official 0:51ac1d130fd4 659 pcb->rtime = 0;
mbed_official 0:51ac1d130fd4 660 pcb->nrtx = 0;
mbed_official 0:51ac1d130fd4 661 }
mbed_official 0:51ac1d130fd4 662
mbed_official 0:51ac1d130fd4 663 tcp_seg_free(rseg);
mbed_official 0:51ac1d130fd4 664
mbed_official 0:51ac1d130fd4 665 /* Call the user specified function to call when sucessfully
mbed_official 0:51ac1d130fd4 666 * connected. */
mbed_official 0:51ac1d130fd4 667 TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
mbed_official 0:51ac1d130fd4 668 if (err == ERR_ABRT) {
mbed_official 0:51ac1d130fd4 669 return ERR_ABRT;
mbed_official 0:51ac1d130fd4 670 }
mbed_official 0:51ac1d130fd4 671 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 672 }
mbed_official 0:51ac1d130fd4 673 /* received ACK? possibly a half-open connection */
mbed_official 0:51ac1d130fd4 674 else if (flags & TCP_ACK) {
mbed_official 0:51ac1d130fd4 675 /* send a RST to bring the other side in a non-synchronized state. */
mbed_official 0:51ac1d130fd4 676 tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
mbed_official 0:51ac1d130fd4 677 tcphdr->dest, tcphdr->src);
mbed_official 0:51ac1d130fd4 678 }
mbed_official 0:51ac1d130fd4 679 break;
mbed_official 0:51ac1d130fd4 680 case SYN_RCVD:
mbed_official 0:51ac1d130fd4 681 if (flags & TCP_ACK) {
mbed_official 0:51ac1d130fd4 682 /* expected ACK number? */
mbed_official 0:51ac1d130fd4 683 if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
mbed_official 0:51ac1d130fd4 684 u16_t old_cwnd;
mbed_official 0:51ac1d130fd4 685 pcb->state = ESTABLISHED;
mbed_official 0:51ac1d130fd4 686 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed_official 0:51ac1d130fd4 687 #if LWIP_CALLBACK_API
mbed_official 0:51ac1d130fd4 688 LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
mbed_official 0:51ac1d130fd4 689 #endif
mbed_official 0:51ac1d130fd4 690 /* Call the accept function. */
mbed_official 0:51ac1d130fd4 691 TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
mbed_official 0:51ac1d130fd4 692 if (err != ERR_OK) {
mbed_official 0:51ac1d130fd4 693 /* If the accept function returns with an error, we abort
mbed_official 0:51ac1d130fd4 694 * the connection. */
mbed_official 0:51ac1d130fd4 695 /* Already aborted? */
mbed_official 0:51ac1d130fd4 696 if (err != ERR_ABRT) {
mbed_official 0:51ac1d130fd4 697 tcp_abort(pcb);
mbed_official 0:51ac1d130fd4 698 }
mbed_official 0:51ac1d130fd4 699 return ERR_ABRT;
mbed_official 0:51ac1d130fd4 700 }
mbed_official 0:51ac1d130fd4 701 old_cwnd = pcb->cwnd;
mbed_official 0:51ac1d130fd4 702 /* If there was any data contained within this ACK,
mbed_official 0:51ac1d130fd4 703 * we'd better pass it on to the application as well. */
mbed_official 0:51ac1d130fd4 704 tcp_receive(pcb);
mbed_official 0:51ac1d130fd4 705
mbed_official 0:51ac1d130fd4 706 /* Prevent ACK for SYN to generate a sent event */
mbed_official 0:51ac1d130fd4 707 if (pcb->acked != 0) {
mbed_official 0:51ac1d130fd4 708 pcb->acked--;
mbed_official 0:51ac1d130fd4 709 }
mbed_official 0:51ac1d130fd4 710
mbed_official 0:51ac1d130fd4 711 pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
mbed_official 0:51ac1d130fd4 712
mbed_official 0:51ac1d130fd4 713 if (recv_flags & TF_GOT_FIN) {
mbed_official 0:51ac1d130fd4 714 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 715 pcb->state = CLOSE_WAIT;
mbed_official 0:51ac1d130fd4 716 }
mbed_official 0:51ac1d130fd4 717 } else {
mbed_official 0:51ac1d130fd4 718 /* incorrect ACK number, send RST */
mbed_official 0:51ac1d130fd4 719 tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
mbed_official 0:51ac1d130fd4 720 tcphdr->dest, tcphdr->src);
mbed_official 0:51ac1d130fd4 721 }
mbed_official 0:51ac1d130fd4 722 } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
mbed_official 0:51ac1d130fd4 723 /* Looks like another copy of the SYN - retransmit our SYN-ACK */
mbed_official 0:51ac1d130fd4 724 tcp_rexmit(pcb);
mbed_official 0:51ac1d130fd4 725 }
mbed_official 0:51ac1d130fd4 726 break;
mbed_official 0:51ac1d130fd4 727 case CLOSE_WAIT:
mbed_official 0:51ac1d130fd4 728 /* FALLTHROUGH */
mbed_official 0:51ac1d130fd4 729 case ESTABLISHED:
mbed_official 0:51ac1d130fd4 730 tcp_receive(pcb);
mbed_official 0:51ac1d130fd4 731 if (recv_flags & TF_GOT_FIN) { /* passive close */
mbed_official 0:51ac1d130fd4 732 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 733 pcb->state = CLOSE_WAIT;
mbed_official 0:51ac1d130fd4 734 }
mbed_official 0:51ac1d130fd4 735 break;
mbed_official 0:51ac1d130fd4 736 case FIN_WAIT_1:
mbed_official 0:51ac1d130fd4 737 tcp_receive(pcb);
mbed_official 0:51ac1d130fd4 738 if (recv_flags & TF_GOT_FIN) {
mbed_official 0:51ac1d130fd4 739 if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
mbed_official 0:51ac1d130fd4 740 LWIP_DEBUGF(TCP_DEBUG,
mbed_official 0:51ac1d130fd4 741 ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed_official 0:51ac1d130fd4 742 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 743 tcp_pcb_purge(pcb);
mbed_official 0:51ac1d130fd4 744 TCP_RMV(&tcp_active_pcbs, pcb);
mbed_official 0:51ac1d130fd4 745 pcb->state = TIME_WAIT;
mbed_official 0:51ac1d130fd4 746 TCP_REG(&tcp_tw_pcbs, pcb);
mbed_official 0:51ac1d130fd4 747 } else {
mbed_official 0:51ac1d130fd4 748 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 749 pcb->state = CLOSING;
mbed_official 0:51ac1d130fd4 750 }
mbed_official 0:51ac1d130fd4 751 } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
mbed_official 0:51ac1d130fd4 752 pcb->state = FIN_WAIT_2;
mbed_official 0:51ac1d130fd4 753 }
mbed_official 0:51ac1d130fd4 754 break;
mbed_official 0:51ac1d130fd4 755 case FIN_WAIT_2:
mbed_official 0:51ac1d130fd4 756 tcp_receive(pcb);
mbed_official 0:51ac1d130fd4 757 if (recv_flags & TF_GOT_FIN) {
mbed_official 0:51ac1d130fd4 758 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed_official 0:51ac1d130fd4 759 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 760 tcp_pcb_purge(pcb);
mbed_official 0:51ac1d130fd4 761 TCP_RMV(&tcp_active_pcbs, pcb);
mbed_official 0:51ac1d130fd4 762 pcb->state = TIME_WAIT;
mbed_official 0:51ac1d130fd4 763 TCP_REG(&tcp_tw_pcbs, pcb);
mbed_official 0:51ac1d130fd4 764 }
mbed_official 0:51ac1d130fd4 765 break;
mbed_official 0:51ac1d130fd4 766 case CLOSING:
mbed_official 0:51ac1d130fd4 767 tcp_receive(pcb);
mbed_official 0:51ac1d130fd4 768 if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
mbed_official 0:51ac1d130fd4 769 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed_official 0:51ac1d130fd4 770 tcp_pcb_purge(pcb);
mbed_official 0:51ac1d130fd4 771 TCP_RMV(&tcp_active_pcbs, pcb);
mbed_official 0:51ac1d130fd4 772 pcb->state = TIME_WAIT;
mbed_official 0:51ac1d130fd4 773 TCP_REG(&tcp_tw_pcbs, pcb);
mbed_official 0:51ac1d130fd4 774 }
mbed_official 0:51ac1d130fd4 775 break;
mbed_official 0:51ac1d130fd4 776 case LAST_ACK:
mbed_official 0:51ac1d130fd4 777 tcp_receive(pcb);
mbed_official 0:51ac1d130fd4 778 if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
mbed_official 0:51ac1d130fd4 779 LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
mbed_official 0:51ac1d130fd4 780 /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
mbed_official 0:51ac1d130fd4 781 recv_flags |= TF_CLOSED;
mbed_official 0:51ac1d130fd4 782 }
mbed_official 0:51ac1d130fd4 783 break;
mbed_official 0:51ac1d130fd4 784 default:
mbed_official 0:51ac1d130fd4 785 break;
mbed_official 0:51ac1d130fd4 786 }
mbed_official 0:51ac1d130fd4 787 return ERR_OK;
mbed_official 0:51ac1d130fd4 788 }
mbed_official 0:51ac1d130fd4 789
mbed_official 0:51ac1d130fd4 790 #if TCP_QUEUE_OOSEQ
mbed_official 0:51ac1d130fd4 791 /**
mbed_official 0:51ac1d130fd4 792 * Insert segment into the list (segments covered with new one will be deleted)
mbed_official 0:51ac1d130fd4 793 *
mbed_official 0:51ac1d130fd4 794 * Called from tcp_receive()
mbed_official 0:51ac1d130fd4 795 */
mbed_official 0:51ac1d130fd4 796 static void
mbed_official 0:51ac1d130fd4 797 tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
mbed_official 0:51ac1d130fd4 798 {
mbed_official 0:51ac1d130fd4 799 struct tcp_seg *old_seg;
mbed_official 0:51ac1d130fd4 800
mbed_official 0:51ac1d130fd4 801 if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 802 /* received segment overlaps all following segments */
mbed_official 0:51ac1d130fd4 803 tcp_segs_free(next);
mbed_official 0:51ac1d130fd4 804 next = NULL;
mbed_official 0:51ac1d130fd4 805 }
mbed_official 0:51ac1d130fd4 806 else {
mbed_official 0:51ac1d130fd4 807 /* delete some following segments
mbed_official 0:51ac1d130fd4 808 oos queue may have segments with FIN flag */
mbed_official 0:51ac1d130fd4 809 while (next &&
mbed_official 0:51ac1d130fd4 810 TCP_SEQ_GEQ((seqno + cseg->len),
mbed_official 0:51ac1d130fd4 811 (next->tcphdr->seqno + next->len))) {
mbed_official 0:51ac1d130fd4 812 /* cseg with FIN already processed */
mbed_official 0:51ac1d130fd4 813 if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 814 TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
mbed_official 0:51ac1d130fd4 815 }
mbed_official 0:51ac1d130fd4 816 old_seg = next;
mbed_official 0:51ac1d130fd4 817 next = next->next;
mbed_official 0:51ac1d130fd4 818 tcp_seg_free(old_seg);
mbed_official 0:51ac1d130fd4 819 }
mbed_official 0:51ac1d130fd4 820 if (next &&
mbed_official 0:51ac1d130fd4 821 TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
mbed_official 0:51ac1d130fd4 822 /* We need to trim the incoming segment. */
mbed_official 0:51ac1d130fd4 823 cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
mbed_official 0:51ac1d130fd4 824 pbuf_realloc(cseg->p, cseg->len);
mbed_official 0:51ac1d130fd4 825 }
mbed_official 0:51ac1d130fd4 826 }
mbed_official 0:51ac1d130fd4 827 cseg->next = next;
mbed_official 0:51ac1d130fd4 828 }
mbed_official 0:51ac1d130fd4 829 #endif /* TCP_QUEUE_OOSEQ */
mbed_official 0:51ac1d130fd4 830
mbed_official 0:51ac1d130fd4 831 /**
mbed_official 0:51ac1d130fd4 832 * Called by tcp_process. Checks if the given segment is an ACK for outstanding
mbed_official 0:51ac1d130fd4 833 * data, and if so frees the memory of the buffered data. Next, is places the
mbed_official 0:51ac1d130fd4 834 * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
mbed_official 0:51ac1d130fd4 835 * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
mbed_official 0:51ac1d130fd4 836 * i it has been removed from the buffer.
mbed_official 0:51ac1d130fd4 837 *
mbed_official 0:51ac1d130fd4 838 * If the incoming segment constitutes an ACK for a segment that was used for RTT
mbed_official 0:51ac1d130fd4 839 * estimation, the RTT is estimated here as well.
mbed_official 0:51ac1d130fd4 840 *
mbed_official 0:51ac1d130fd4 841 * Called from tcp_process().
mbed_official 0:51ac1d130fd4 842 */
mbed_official 0:51ac1d130fd4 843 static void
mbed_official 0:51ac1d130fd4 844 tcp_receive(struct tcp_pcb *pcb)
mbed_official 0:51ac1d130fd4 845 {
mbed_official 0:51ac1d130fd4 846 struct tcp_seg *next;
mbed_official 0:51ac1d130fd4 847 #if TCP_QUEUE_OOSEQ
mbed_official 0:51ac1d130fd4 848 struct tcp_seg *prev, *cseg;
mbed_official 0:51ac1d130fd4 849 #endif /* TCP_QUEUE_OOSEQ */
mbed_official 0:51ac1d130fd4 850 struct pbuf *p;
mbed_official 0:51ac1d130fd4 851 s32_t off;
mbed_official 0:51ac1d130fd4 852 s16_t m;
mbed_official 0:51ac1d130fd4 853 u32_t right_wnd_edge;
mbed_official 0:51ac1d130fd4 854 u16_t new_tot_len;
mbed_official 0:51ac1d130fd4 855 int found_dupack = 0;
mbed_official 0:51ac1d130fd4 856
mbed_official 0:51ac1d130fd4 857 if (flags & TCP_ACK) {
mbed_official 0:51ac1d130fd4 858 right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
mbed_official 0:51ac1d130fd4 859
mbed_official 0:51ac1d130fd4 860 /* Update window. */
mbed_official 0:51ac1d130fd4 861 if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
mbed_official 0:51ac1d130fd4 862 (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
mbed_official 0:51ac1d130fd4 863 (pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
mbed_official 0:51ac1d130fd4 864 pcb->snd_wnd = tcphdr->wnd;
mbed_official 0:51ac1d130fd4 865 pcb->snd_wl1 = seqno;
mbed_official 0:51ac1d130fd4 866 pcb->snd_wl2 = ackno;
mbed_official 0:51ac1d130fd4 867 if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
mbed_official 0:51ac1d130fd4 868 pcb->persist_backoff = 0;
mbed_official 0:51ac1d130fd4 869 }
mbed_official 0:51ac1d130fd4 870 LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
mbed_official 0:51ac1d130fd4 871 #if TCP_WND_DEBUG
mbed_official 0:51ac1d130fd4 872 } else {
mbed_official 0:51ac1d130fd4 873 if (pcb->snd_wnd != tcphdr->wnd) {
mbed_official 0:51ac1d130fd4 874 LWIP_DEBUGF(TCP_WND_DEBUG,
mbed_official 0:51ac1d130fd4 875 ("tcp_receive: no window update lastack %"U32_F" ackno %"
mbed_official 0:51ac1d130fd4 876 U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
mbed_official 0:51ac1d130fd4 877 pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
mbed_official 0:51ac1d130fd4 878 }
mbed_official 0:51ac1d130fd4 879 #endif /* TCP_WND_DEBUG */
mbed_official 0:51ac1d130fd4 880 }
mbed_official 0:51ac1d130fd4 881
mbed_official 0:51ac1d130fd4 882 /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
mbed_official 0:51ac1d130fd4 883 * duplicate ack if:
mbed_official 0:51ac1d130fd4 884 * 1) It doesn't ACK new data
mbed_official 0:51ac1d130fd4 885 * 2) length of received packet is zero (i.e. no payload)
mbed_official 0:51ac1d130fd4 886 * 3) the advertised window hasn't changed
mbed_official 0:51ac1d130fd4 887 * 4) There is outstanding unacknowledged data (retransmission timer running)
mbed_official 0:51ac1d130fd4 888 * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
mbed_official 0:51ac1d130fd4 889 *
mbed_official 0:51ac1d130fd4 890 * If it passes all five, should process as a dupack:
mbed_official 0:51ac1d130fd4 891 * a) dupacks < 3: do nothing
mbed_official 0:51ac1d130fd4 892 * b) dupacks == 3: fast retransmit
mbed_official 0:51ac1d130fd4 893 * c) dupacks > 3: increase cwnd
mbed_official 0:51ac1d130fd4 894 *
mbed_official 0:51ac1d130fd4 895 * If it only passes 1-3, should reset dupack counter (and add to
mbed_official 0:51ac1d130fd4 896 * stats, which we don't do in lwIP)
mbed_official 0:51ac1d130fd4 897 *
mbed_official 0:51ac1d130fd4 898 * If it only passes 1, should reset dupack counter
mbed_official 0:51ac1d130fd4 899 *
mbed_official 0:51ac1d130fd4 900 */
mbed_official 0:51ac1d130fd4 901
mbed_official 0:51ac1d130fd4 902 /* Clause 1 */
mbed_official 0:51ac1d130fd4 903 if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
mbed_official 0:51ac1d130fd4 904 pcb->acked = 0;
mbed_official 0:51ac1d130fd4 905 /* Clause 2 */
mbed_official 0:51ac1d130fd4 906 if (tcplen == 0) {
mbed_official 0:51ac1d130fd4 907 /* Clause 3 */
mbed_official 0:51ac1d130fd4 908 if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
mbed_official 0:51ac1d130fd4 909 /* Clause 4 */
mbed_official 0:51ac1d130fd4 910 if (pcb->rtime >= 0) {
mbed_official 0:51ac1d130fd4 911 /* Clause 5 */
mbed_official 0:51ac1d130fd4 912 if (pcb->lastack == ackno) {
mbed_official 0:51ac1d130fd4 913 found_dupack = 1;
mbed_official 0:51ac1d130fd4 914 if (pcb->dupacks + 1 > pcb->dupacks)
mbed_official 0:51ac1d130fd4 915 ++pcb->dupacks;
mbed_official 0:51ac1d130fd4 916 if (pcb->dupacks > 3) {
mbed_official 0:51ac1d130fd4 917 /* Inflate the congestion window, but not if it means that
mbed_official 0:51ac1d130fd4 918 the value overflows. */
mbed_official 0:51ac1d130fd4 919 if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
mbed_official 0:51ac1d130fd4 920 pcb->cwnd += pcb->mss;
mbed_official 0:51ac1d130fd4 921 }
mbed_official 0:51ac1d130fd4 922 } else if (pcb->dupacks == 3) {
mbed_official 0:51ac1d130fd4 923 /* Do fast retransmit */
mbed_official 0:51ac1d130fd4 924 tcp_rexmit_fast(pcb);
mbed_official 0:51ac1d130fd4 925 }
mbed_official 0:51ac1d130fd4 926 }
mbed_official 0:51ac1d130fd4 927 }
mbed_official 0:51ac1d130fd4 928 }
mbed_official 0:51ac1d130fd4 929 }
mbed_official 0:51ac1d130fd4 930 /* If Clause (1) or more is true, but not a duplicate ack, reset
mbed_official 0:51ac1d130fd4 931 * count of consecutive duplicate acks */
mbed_official 0:51ac1d130fd4 932 if (!found_dupack) {
mbed_official 0:51ac1d130fd4 933 pcb->dupacks = 0;
mbed_official 0:51ac1d130fd4 934 }
mbed_official 0:51ac1d130fd4 935 } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
mbed_official 0:51ac1d130fd4 936 /* We come here when the ACK acknowledges new data. */
mbed_official 0:51ac1d130fd4 937
mbed_official 0:51ac1d130fd4 938 /* Reset the "IN Fast Retransmit" flag, since we are no longer
mbed_official 0:51ac1d130fd4 939 in fast retransmit. Also reset the congestion window to the
mbed_official 0:51ac1d130fd4 940 slow start threshold. */
mbed_official 0:51ac1d130fd4 941 if (pcb->flags & TF_INFR) {
mbed_official 0:51ac1d130fd4 942 pcb->flags &= ~TF_INFR;
mbed_official 0:51ac1d130fd4 943 pcb->cwnd = pcb->ssthresh;
mbed_official 0:51ac1d130fd4 944 }
mbed_official 0:51ac1d130fd4 945
mbed_official 0:51ac1d130fd4 946 /* Reset the number of retransmissions. */
mbed_official 0:51ac1d130fd4 947 pcb->nrtx = 0;
mbed_official 0:51ac1d130fd4 948
mbed_official 0:51ac1d130fd4 949 /* Reset the retransmission time-out. */
mbed_official 0:51ac1d130fd4 950 pcb->rto = (pcb->sa >> 3) + pcb->sv;
mbed_official 0:51ac1d130fd4 951
mbed_official 0:51ac1d130fd4 952 /* Update the send buffer space. Diff between the two can never exceed 64K? */
mbed_official 0:51ac1d130fd4 953 pcb->acked = (u16_t)(ackno - pcb->lastack);
mbed_official 0:51ac1d130fd4 954
mbed_official 0:51ac1d130fd4 955 pcb->snd_buf += pcb->acked;
mbed_official 0:51ac1d130fd4 956
mbed_official 0:51ac1d130fd4 957 /* Reset the fast retransmit variables. */
mbed_official 0:51ac1d130fd4 958 pcb->dupacks = 0;
mbed_official 0:51ac1d130fd4 959 pcb->lastack = ackno;
mbed_official 0:51ac1d130fd4 960
mbed_official 0:51ac1d130fd4 961 /* Update the congestion control variables (cwnd and
mbed_official 0:51ac1d130fd4 962 ssthresh). */
mbed_official 0:51ac1d130fd4 963 if (pcb->state >= ESTABLISHED) {
mbed_official 0:51ac1d130fd4 964 if (pcb->cwnd < pcb->ssthresh) {
mbed_official 0:51ac1d130fd4 965 if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
mbed_official 0:51ac1d130fd4 966 pcb->cwnd += pcb->mss;
mbed_official 0:51ac1d130fd4 967 }
mbed_official 0:51ac1d130fd4 968 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
mbed_official 0:51ac1d130fd4 969 } else {
mbed_official 0:51ac1d130fd4 970 u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
mbed_official 0:51ac1d130fd4 971 if (new_cwnd > pcb->cwnd) {
mbed_official 0:51ac1d130fd4 972 pcb->cwnd = new_cwnd;
mbed_official 0:51ac1d130fd4 973 }
mbed_official 0:51ac1d130fd4 974 LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
mbed_official 0:51ac1d130fd4 975 }
mbed_official 0:51ac1d130fd4 976 }
mbed_official 0:51ac1d130fd4 977 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
mbed_official 0:51ac1d130fd4 978 ackno,
mbed_official 0:51ac1d130fd4 979 pcb->unacked != NULL?
mbed_official 0:51ac1d130fd4 980 ntohl(pcb->unacked->tcphdr->seqno): 0,
mbed_official 0:51ac1d130fd4 981 pcb->unacked != NULL?
mbed_official 0:51ac1d130fd4 982 ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
mbed_official 0:51ac1d130fd4 983
mbed_official 0:51ac1d130fd4 984 /* Remove segment from the unacknowledged list if the incoming
mbed_official 0:51ac1d130fd4 985 ACK acknowlegdes them. */
mbed_official 0:51ac1d130fd4 986 while (pcb->unacked != NULL &&
mbed_official 0:51ac1d130fd4 987 TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
mbed_official 0:51ac1d130fd4 988 TCP_TCPLEN(pcb->unacked), ackno)) {
mbed_official 0:51ac1d130fd4 989 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
mbed_official 0:51ac1d130fd4 990 ntohl(pcb->unacked->tcphdr->seqno),
mbed_official 0:51ac1d130fd4 991 ntohl(pcb->unacked->tcphdr->seqno) +
mbed_official 0:51ac1d130fd4 992 TCP_TCPLEN(pcb->unacked)));
mbed_official 0:51ac1d130fd4 993
mbed_official 0:51ac1d130fd4 994 next = pcb->unacked;
mbed_official 0:51ac1d130fd4 995 pcb->unacked = pcb->unacked->next;
mbed_official 0:51ac1d130fd4 996
mbed_official 0:51ac1d130fd4 997 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
mbed_official 0:51ac1d130fd4 998 LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
mbed_official 0:51ac1d130fd4 999 /* Prevent ACK for FIN to generate a sent event */
mbed_official 0:51ac1d130fd4 1000 if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
mbed_official 0:51ac1d130fd4 1001 pcb->acked--;
mbed_official 0:51ac1d130fd4 1002 }
mbed_official 0:51ac1d130fd4 1003
mbed_official 0:51ac1d130fd4 1004 pcb->snd_queuelen -= pbuf_clen(next->p);
mbed_official 0:51ac1d130fd4 1005 tcp_seg_free(next);
mbed_official 0:51ac1d130fd4 1006
mbed_official 0:51ac1d130fd4 1007 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
mbed_official 0:51ac1d130fd4 1008 if (pcb->snd_queuelen != 0) {
mbed_official 0:51ac1d130fd4 1009 LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
mbed_official 0:51ac1d130fd4 1010 pcb->unsent != NULL);
mbed_official 0:51ac1d130fd4 1011 }
mbed_official 0:51ac1d130fd4 1012 }
mbed_official 0:51ac1d130fd4 1013
mbed_official 0:51ac1d130fd4 1014 /* If there's nothing left to acknowledge, stop the retransmit
mbed_official 0:51ac1d130fd4 1015 timer, otherwise reset it to start again */
mbed_official 0:51ac1d130fd4 1016 if(pcb->unacked == NULL)
mbed_official 0:51ac1d130fd4 1017 pcb->rtime = -1;
mbed_official 0:51ac1d130fd4 1018 else
mbed_official 0:51ac1d130fd4 1019 pcb->rtime = 0;
mbed_official 0:51ac1d130fd4 1020
mbed_official 0:51ac1d130fd4 1021 pcb->polltmr = 0;
mbed_official 0:51ac1d130fd4 1022 } else {
mbed_official 0:51ac1d130fd4 1023 /* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
mbed_official 0:51ac1d130fd4 1024 pcb->acked = 0;
mbed_official 0:51ac1d130fd4 1025 }
mbed_official 0:51ac1d130fd4 1026
mbed_official 0:51ac1d130fd4 1027 /* We go through the ->unsent list to see if any of the segments
mbed_official 0:51ac1d130fd4 1028 on the list are acknowledged by the ACK. This may seem
mbed_official 0:51ac1d130fd4 1029 strange since an "unsent" segment shouldn't be acked. The
mbed_official 0:51ac1d130fd4 1030 rationale is that lwIP puts all outstanding segments on the
mbed_official 0:51ac1d130fd4 1031 ->unsent list after a retransmission, so these segments may
mbed_official 0:51ac1d130fd4 1032 in fact have been sent once. */
mbed_official 0:51ac1d130fd4 1033 while (pcb->unsent != NULL &&
mbed_official 0:51ac1d130fd4 1034 TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
mbed_official 0:51ac1d130fd4 1035 TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
mbed_official 0:51ac1d130fd4 1036 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
mbed_official 0:51ac1d130fd4 1037 ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
mbed_official 0:51ac1d130fd4 1038 TCP_TCPLEN(pcb->unsent)));
mbed_official 0:51ac1d130fd4 1039
mbed_official 0:51ac1d130fd4 1040 next = pcb->unsent;
mbed_official 0:51ac1d130fd4 1041 pcb->unsent = pcb->unsent->next;
mbed_official 0:51ac1d130fd4 1042 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
mbed_official 0:51ac1d130fd4 1043 LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
mbed_official 0:51ac1d130fd4 1044 /* Prevent ACK for FIN to generate a sent event */
mbed_official 0:51ac1d130fd4 1045 if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
mbed_official 0:51ac1d130fd4 1046 pcb->acked--;
mbed_official 0:51ac1d130fd4 1047 }
mbed_official 0:51ac1d130fd4 1048 pcb->snd_queuelen -= pbuf_clen(next->p);
mbed_official 0:51ac1d130fd4 1049 tcp_seg_free(next);
mbed_official 0:51ac1d130fd4 1050 LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
mbed_official 0:51ac1d130fd4 1051 if (pcb->snd_queuelen != 0) {
mbed_official 0:51ac1d130fd4 1052 LWIP_ASSERT("tcp_receive: valid queue length",
mbed_official 0:51ac1d130fd4 1053 pcb->unacked != NULL || pcb->unsent != NULL);
mbed_official 0:51ac1d130fd4 1054 }
mbed_official 0:51ac1d130fd4 1055 }
mbed_official 0:51ac1d130fd4 1056 /* End of ACK for new data processing. */
mbed_official 0:51ac1d130fd4 1057
mbed_official 0:51ac1d130fd4 1058 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
mbed_official 0:51ac1d130fd4 1059 pcb->rttest, pcb->rtseq, ackno));
mbed_official 0:51ac1d130fd4 1060
mbed_official 0:51ac1d130fd4 1061 /* RTT estimation calculations. This is done by checking if the
mbed_official 0:51ac1d130fd4 1062 incoming segment acknowledges the segment we use to take a
mbed_official 0:51ac1d130fd4 1063 round-trip time measurement. */
mbed_official 0:51ac1d130fd4 1064 if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
mbed_official 0:51ac1d130fd4 1065 /* diff between this shouldn't exceed 32K since this are tcp timer ticks
mbed_official 0:51ac1d130fd4 1066 and a round-trip shouldn't be that long... */
mbed_official 0:51ac1d130fd4 1067 m = (s16_t)(tcp_ticks - pcb->rttest);
mbed_official 0:51ac1d130fd4 1068
mbed_official 0:51ac1d130fd4 1069 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
mbed_official 0:51ac1d130fd4 1070 m, m * TCP_SLOW_INTERVAL));
mbed_official 0:51ac1d130fd4 1071
mbed_official 0:51ac1d130fd4 1072 /* This is taken directly from VJs original code in his paper */
mbed_official 0:51ac1d130fd4 1073 m = m - (pcb->sa >> 3);
mbed_official 0:51ac1d130fd4 1074 pcb->sa += m;
mbed_official 0:51ac1d130fd4 1075 if (m < 0) {
mbed_official 0:51ac1d130fd4 1076 m = -m;
mbed_official 0:51ac1d130fd4 1077 }
mbed_official 0:51ac1d130fd4 1078 m = m - (pcb->sv >> 2);
mbed_official 0:51ac1d130fd4 1079 pcb->sv += m;
mbed_official 0:51ac1d130fd4 1080 pcb->rto = (pcb->sa >> 3) + pcb->sv;
mbed_official 0:51ac1d130fd4 1081
mbed_official 0:51ac1d130fd4 1082 LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
mbed_official 0:51ac1d130fd4 1083 pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
mbed_official 0:51ac1d130fd4 1084
mbed_official 0:51ac1d130fd4 1085 pcb->rttest = 0;
mbed_official 0:51ac1d130fd4 1086 }
mbed_official 0:51ac1d130fd4 1087 }
mbed_official 0:51ac1d130fd4 1088
mbed_official 0:51ac1d130fd4 1089 /* If the incoming segment contains data, we must process it
mbed_official 0:51ac1d130fd4 1090 further. */
mbed_official 0:51ac1d130fd4 1091 if (tcplen > 0) {
mbed_official 0:51ac1d130fd4 1092 /* This code basically does three things:
mbed_official 0:51ac1d130fd4 1093
mbed_official 0:51ac1d130fd4 1094 +) If the incoming segment contains data that is the next
mbed_official 0:51ac1d130fd4 1095 in-sequence data, this data is passed to the application. This
mbed_official 0:51ac1d130fd4 1096 might involve trimming the first edge of the data. The rcv_nxt
mbed_official 0:51ac1d130fd4 1097 variable and the advertised window are adjusted.
mbed_official 0:51ac1d130fd4 1098
mbed_official 0:51ac1d130fd4 1099 +) If the incoming segment has data that is above the next
mbed_official 0:51ac1d130fd4 1100 sequence number expected (->rcv_nxt), the segment is placed on
mbed_official 0:51ac1d130fd4 1101 the ->ooseq queue. This is done by finding the appropriate
mbed_official 0:51ac1d130fd4 1102 place in the ->ooseq queue (which is ordered by sequence
mbed_official 0:51ac1d130fd4 1103 number) and trim the segment in both ends if needed. An
mbed_official 0:51ac1d130fd4 1104 immediate ACK is sent to indicate that we received an
mbed_official 0:51ac1d130fd4 1105 out-of-sequence segment.
mbed_official 0:51ac1d130fd4 1106
mbed_official 0:51ac1d130fd4 1107 +) Finally, we check if the first segment on the ->ooseq queue
mbed_official 0:51ac1d130fd4 1108 now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
mbed_official 0:51ac1d130fd4 1109 rcv_nxt > ooseq->seqno, we must trim the first edge of the
mbed_official 0:51ac1d130fd4 1110 segment on ->ooseq before we adjust rcv_nxt. The data in the
mbed_official 0:51ac1d130fd4 1111 segments that are now on sequence are chained onto the
mbed_official 0:51ac1d130fd4 1112 incoming segment so that we only need to call the application
mbed_official 0:51ac1d130fd4 1113 once.
mbed_official 0:51ac1d130fd4 1114 */
mbed_official 0:51ac1d130fd4 1115
mbed_official 0:51ac1d130fd4 1116 /* First, we check if we must trim the first edge. We have to do
mbed_official 0:51ac1d130fd4 1117 this if the sequence number of the incoming segment is less
mbed_official 0:51ac1d130fd4 1118 than rcv_nxt, and the sequence number plus the length of the
mbed_official 0:51ac1d130fd4 1119 segment is larger than rcv_nxt. */
mbed_official 0:51ac1d130fd4 1120 /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
mbed_official 0:51ac1d130fd4 1121 if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
mbed_official 0:51ac1d130fd4 1122 if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
mbed_official 0:51ac1d130fd4 1123 /* Trimming the first edge is done by pushing the payload
mbed_official 0:51ac1d130fd4 1124 pointer in the pbuf downwards. This is somewhat tricky since
mbed_official 0:51ac1d130fd4 1125 we do not want to discard the full contents of the pbuf up to
mbed_official 0:51ac1d130fd4 1126 the new starting point of the data since we have to keep the
mbed_official 0:51ac1d130fd4 1127 TCP header which is present in the first pbuf in the chain.
mbed_official 0:51ac1d130fd4 1128
mbed_official 0:51ac1d130fd4 1129 What is done is really quite a nasty hack: the first pbuf in
mbed_official 0:51ac1d130fd4 1130 the pbuf chain is pointed to by inseg.p. Since we need to be
mbed_official 0:51ac1d130fd4 1131 able to deallocate the whole pbuf, we cannot change this
mbed_official 0:51ac1d130fd4 1132 inseg.p pointer to point to any of the later pbufs in the
mbed_official 0:51ac1d130fd4 1133 chain. Instead, we point the ->payload pointer in the first
mbed_official 0:51ac1d130fd4 1134 pbuf to data in one of the later pbufs. We also set the
mbed_official 0:51ac1d130fd4 1135 inseg.data pointer to point to the right place. This way, the
mbed_official 0:51ac1d130fd4 1136 ->p pointer will still point to the first pbuf, but the
mbed_official 0:51ac1d130fd4 1137 ->p->payload pointer will point to data in another pbuf.
mbed_official 0:51ac1d130fd4 1138
mbed_official 0:51ac1d130fd4 1139 After we are done with adjusting the pbuf pointers we must
mbed_official 0:51ac1d130fd4 1140 adjust the ->data pointer in the seg and the segment
mbed_official 0:51ac1d130fd4 1141 length.*/
mbed_official 0:51ac1d130fd4 1142
mbed_official 0:51ac1d130fd4 1143 off = pcb->rcv_nxt - seqno;
mbed_official 0:51ac1d130fd4 1144 p = inseg.p;
mbed_official 0:51ac1d130fd4 1145 LWIP_ASSERT("inseg.p != NULL", inseg.p);
mbed_official 0:51ac1d130fd4 1146 LWIP_ASSERT("insane offset!", (off < 0x7fff));
mbed_official 0:51ac1d130fd4 1147 if (inseg.p->len < off) {
mbed_official 0:51ac1d130fd4 1148 LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
mbed_official 0:51ac1d130fd4 1149 new_tot_len = (u16_t)(inseg.p->tot_len - off);
mbed_official 0:51ac1d130fd4 1150 while (p->len < off) {
mbed_official 0:51ac1d130fd4 1151 off -= p->len;
mbed_official 0:51ac1d130fd4 1152 /* KJM following line changed (with addition of new_tot_len var)
mbed_official 0:51ac1d130fd4 1153 to fix bug #9076
mbed_official 0:51ac1d130fd4 1154 inseg.p->tot_len -= p->len; */
mbed_official 0:51ac1d130fd4 1155 p->tot_len = new_tot_len;
mbed_official 0:51ac1d130fd4 1156 p->len = 0;
mbed_official 0:51ac1d130fd4 1157 p = p->next;
mbed_official 0:51ac1d130fd4 1158 }
mbed_official 0:51ac1d130fd4 1159 if(pbuf_header(p, (s16_t)-off)) {
mbed_official 0:51ac1d130fd4 1160 /* Do we need to cope with this failing? Assert for now */
mbed_official 0:51ac1d130fd4 1161 LWIP_ASSERT("pbuf_header failed", 0);
mbed_official 0:51ac1d130fd4 1162 }
mbed_official 0:51ac1d130fd4 1163 } else {
mbed_official 0:51ac1d130fd4 1164 if(pbuf_header(inseg.p, (s16_t)-off)) {
mbed_official 0:51ac1d130fd4 1165 /* Do we need to cope with this failing? Assert for now */
mbed_official 0:51ac1d130fd4 1166 LWIP_ASSERT("pbuf_header failed", 0);
mbed_official 0:51ac1d130fd4 1167 }
mbed_official 0:51ac1d130fd4 1168 }
mbed_official 0:51ac1d130fd4 1169 inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
mbed_official 0:51ac1d130fd4 1170 inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
mbed_official 0:51ac1d130fd4 1171 }
mbed_official 0:51ac1d130fd4 1172 else {
mbed_official 0:51ac1d130fd4 1173 if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
mbed_official 0:51ac1d130fd4 1174 /* the whole segment is < rcv_nxt */
mbed_official 0:51ac1d130fd4 1175 /* must be a duplicate of a packet that has already been correctly handled */
mbed_official 0:51ac1d130fd4 1176
mbed_official 0:51ac1d130fd4 1177 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
mbed_official 0:51ac1d130fd4 1178 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 1179 }
mbed_official 0:51ac1d130fd4 1180 }
mbed_official 0:51ac1d130fd4 1181
mbed_official 0:51ac1d130fd4 1182 /* The sequence number must be within the window (above rcv_nxt
mbed_official 0:51ac1d130fd4 1183 and below rcv_nxt + rcv_wnd) in order to be further
mbed_official 0:51ac1d130fd4 1184 processed. */
mbed_official 0:51ac1d130fd4 1185 if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
mbed_official 0:51ac1d130fd4 1186 pcb->rcv_nxt + pcb->rcv_wnd - 1)){
mbed_official 0:51ac1d130fd4 1187 if (pcb->rcv_nxt == seqno) {
mbed_official 0:51ac1d130fd4 1188 /* The incoming segment is the next in sequence. We check if
mbed_official 0:51ac1d130fd4 1189 we have to trim the end of the segment and update rcv_nxt
mbed_official 0:51ac1d130fd4 1190 and pass the data to the application. */
mbed_official 0:51ac1d130fd4 1191 tcplen = TCP_TCPLEN(&inseg);
mbed_official 0:51ac1d130fd4 1192
mbed_official 0:51ac1d130fd4 1193 if (tcplen > pcb->rcv_wnd) {
mbed_official 0:51ac1d130fd4 1194 LWIP_DEBUGF(TCP_INPUT_DEBUG,
mbed_official 0:51ac1d130fd4 1195 ("tcp_receive: other end overran receive window"
mbed_official 0:51ac1d130fd4 1196 "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
mbed_official 0:51ac1d130fd4 1197 seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
mbed_official 0:51ac1d130fd4 1198 if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 1199 /* Must remove the FIN from the header as we're trimming
mbed_official 0:51ac1d130fd4 1200 * that byte of sequence-space from the packet */
mbed_official 0:51ac1d130fd4 1201 TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
mbed_official 0:51ac1d130fd4 1202 }
mbed_official 0:51ac1d130fd4 1203 /* Adjust length of segment to fit in the window. */
mbed_official 0:51ac1d130fd4 1204 inseg.len = pcb->rcv_wnd;
mbed_official 0:51ac1d130fd4 1205 if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
mbed_official 0:51ac1d130fd4 1206 inseg.len -= 1;
mbed_official 0:51ac1d130fd4 1207 }
mbed_official 0:51ac1d130fd4 1208 pbuf_realloc(inseg.p, inseg.len);
mbed_official 0:51ac1d130fd4 1209 tcplen = TCP_TCPLEN(&inseg);
mbed_official 0:51ac1d130fd4 1210 LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
mbed_official 0:51ac1d130fd4 1211 (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
mbed_official 0:51ac1d130fd4 1212 }
mbed_official 0:51ac1d130fd4 1213 #if TCP_QUEUE_OOSEQ
mbed_official 0:51ac1d130fd4 1214 /* Received in-sequence data, adjust ooseq data if:
mbed_official 0:51ac1d130fd4 1215 - FIN has been received or
mbed_official 0:51ac1d130fd4 1216 - inseq overlaps with ooseq */
mbed_official 0:51ac1d130fd4 1217 if (pcb->ooseq != NULL) {
mbed_official 0:51ac1d130fd4 1218 if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 1219 LWIP_DEBUGF(TCP_INPUT_DEBUG,
mbed_official 0:51ac1d130fd4 1220 ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
mbed_official 0:51ac1d130fd4 1221 /* Received in-order FIN means anything that was received
mbed_official 0:51ac1d130fd4 1222 * out of order must now have been received in-order, so
mbed_official 0:51ac1d130fd4 1223 * bin the ooseq queue */
mbed_official 0:51ac1d130fd4 1224 while (pcb->ooseq != NULL) {
mbed_official 0:51ac1d130fd4 1225 struct tcp_seg *old_ooseq = pcb->ooseq;
mbed_official 0:51ac1d130fd4 1226 pcb->ooseq = pcb->ooseq->next;
mbed_official 0:51ac1d130fd4 1227 tcp_seg_free(old_ooseq);
mbed_official 0:51ac1d130fd4 1228 }
mbed_official 0:51ac1d130fd4 1229 }
mbed_official 0:51ac1d130fd4 1230 else {
mbed_official 0:51ac1d130fd4 1231 next = pcb->ooseq;
mbed_official 0:51ac1d130fd4 1232 /* Remove all segments on ooseq that are covered by inseg already.
mbed_official 0:51ac1d130fd4 1233 * FIN is copied from ooseq to inseg if present. */
mbed_official 0:51ac1d130fd4 1234 while (next &&
mbed_official 0:51ac1d130fd4 1235 TCP_SEQ_GEQ(seqno + tcplen,
mbed_official 0:51ac1d130fd4 1236 next->tcphdr->seqno + next->len)) {
mbed_official 0:51ac1d130fd4 1237 /* inseg cannot have FIN here (already processed above) */
mbed_official 0:51ac1d130fd4 1238 if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
mbed_official 0:51ac1d130fd4 1239 (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
mbed_official 0:51ac1d130fd4 1240 TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
mbed_official 0:51ac1d130fd4 1241 tcplen = TCP_TCPLEN(&inseg);
mbed_official 0:51ac1d130fd4 1242 }
mbed_official 0:51ac1d130fd4 1243 prev = next;
mbed_official 0:51ac1d130fd4 1244 next = next->next;
mbed_official 0:51ac1d130fd4 1245 tcp_seg_free(prev);
mbed_official 0:51ac1d130fd4 1246 }
mbed_official 0:51ac1d130fd4 1247 /* Now trim right side of inseg if it overlaps with the first
mbed_official 0:51ac1d130fd4 1248 * segment on ooseq */
mbed_official 0:51ac1d130fd4 1249 if (next &&
mbed_official 0:51ac1d130fd4 1250 TCP_SEQ_GT(seqno + tcplen,
mbed_official 0:51ac1d130fd4 1251 next->tcphdr->seqno)) {
mbed_official 0:51ac1d130fd4 1252 /* inseg cannot have FIN here (already processed above) */
mbed_official 0:51ac1d130fd4 1253 inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
mbed_official 0:51ac1d130fd4 1254 if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
mbed_official 0:51ac1d130fd4 1255 inseg.len -= 1;
mbed_official 0:51ac1d130fd4 1256 }
mbed_official 0:51ac1d130fd4 1257 pbuf_realloc(inseg.p, inseg.len);
mbed_official 0:51ac1d130fd4 1258 tcplen = TCP_TCPLEN(&inseg);
mbed_official 0:51ac1d130fd4 1259 LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
mbed_official 0:51ac1d130fd4 1260 (seqno + tcplen) == next->tcphdr->seqno);
mbed_official 0:51ac1d130fd4 1261 }
mbed_official 0:51ac1d130fd4 1262 pcb->ooseq = next;
mbed_official 0:51ac1d130fd4 1263 }
mbed_official 0:51ac1d130fd4 1264 }
mbed_official 0:51ac1d130fd4 1265 #endif /* TCP_QUEUE_OOSEQ */
mbed_official 0:51ac1d130fd4 1266
mbed_official 0:51ac1d130fd4 1267 pcb->rcv_nxt = seqno + tcplen;
mbed_official 0:51ac1d130fd4 1268
mbed_official 0:51ac1d130fd4 1269 /* Update the receiver's (our) window. */
mbed_official 0:51ac1d130fd4 1270 LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
mbed_official 0:51ac1d130fd4 1271 pcb->rcv_wnd -= tcplen;
mbed_official 0:51ac1d130fd4 1272
mbed_official 0:51ac1d130fd4 1273 tcp_update_rcv_ann_wnd(pcb);
mbed_official 0:51ac1d130fd4 1274
mbed_official 0:51ac1d130fd4 1275 /* If there is data in the segment, we make preparations to
mbed_official 0:51ac1d130fd4 1276 pass this up to the application. The ->recv_data variable
mbed_official 0:51ac1d130fd4 1277 is used for holding the pbuf that goes to the
mbed_official 0:51ac1d130fd4 1278 application. The code for reassembling out-of-sequence data
mbed_official 0:51ac1d130fd4 1279 chains its data on this pbuf as well.
mbed_official 0:51ac1d130fd4 1280
mbed_official 0:51ac1d130fd4 1281 If the segment was a FIN, we set the TF_GOT_FIN flag that will
mbed_official 0:51ac1d130fd4 1282 be used to indicate to the application that the remote side has
mbed_official 0:51ac1d130fd4 1283 closed its end of the connection. */
mbed_official 0:51ac1d130fd4 1284 if (inseg.p->tot_len > 0) {
mbed_official 0:51ac1d130fd4 1285 recv_data = inseg.p;
mbed_official 0:51ac1d130fd4 1286 /* Since this pbuf now is the responsibility of the
mbed_official 0:51ac1d130fd4 1287 application, we delete our reference to it so that we won't
mbed_official 0:51ac1d130fd4 1288 (mistakingly) deallocate it. */
mbed_official 0:51ac1d130fd4 1289 inseg.p = NULL;
mbed_official 0:51ac1d130fd4 1290 }
mbed_official 0:51ac1d130fd4 1291 if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 1292 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
mbed_official 0:51ac1d130fd4 1293 recv_flags |= TF_GOT_FIN;
mbed_official 0:51ac1d130fd4 1294 }
mbed_official 0:51ac1d130fd4 1295
mbed_official 0:51ac1d130fd4 1296 #if TCP_QUEUE_OOSEQ
mbed_official 0:51ac1d130fd4 1297 /* We now check if we have segments on the ->ooseq queue that
mbed_official 0:51ac1d130fd4 1298 are now in sequence. */
mbed_official 0:51ac1d130fd4 1299 while (pcb->ooseq != NULL &&
mbed_official 0:51ac1d130fd4 1300 pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
mbed_official 0:51ac1d130fd4 1301
mbed_official 0:51ac1d130fd4 1302 cseg = pcb->ooseq;
mbed_official 0:51ac1d130fd4 1303 seqno = pcb->ooseq->tcphdr->seqno;
mbed_official 0:51ac1d130fd4 1304
mbed_official 0:51ac1d130fd4 1305 pcb->rcv_nxt += TCP_TCPLEN(cseg);
mbed_official 0:51ac1d130fd4 1306 LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
mbed_official 0:51ac1d130fd4 1307 pcb->rcv_wnd >= TCP_TCPLEN(cseg));
mbed_official 0:51ac1d130fd4 1308 pcb->rcv_wnd -= TCP_TCPLEN(cseg);
mbed_official 0:51ac1d130fd4 1309
mbed_official 0:51ac1d130fd4 1310 tcp_update_rcv_ann_wnd(pcb);
mbed_official 0:51ac1d130fd4 1311
mbed_official 0:51ac1d130fd4 1312 if (cseg->p->tot_len > 0) {
mbed_official 0:51ac1d130fd4 1313 /* Chain this pbuf onto the pbuf that we will pass to
mbed_official 0:51ac1d130fd4 1314 the application. */
mbed_official 0:51ac1d130fd4 1315 if (recv_data) {
mbed_official 0:51ac1d130fd4 1316 pbuf_cat(recv_data, cseg->p);
mbed_official 0:51ac1d130fd4 1317 } else {
mbed_official 0:51ac1d130fd4 1318 recv_data = cseg->p;
mbed_official 0:51ac1d130fd4 1319 }
mbed_official 0:51ac1d130fd4 1320 cseg->p = NULL;
mbed_official 0:51ac1d130fd4 1321 }
mbed_official 0:51ac1d130fd4 1322 if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 1323 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
mbed_official 0:51ac1d130fd4 1324 recv_flags |= TF_GOT_FIN;
mbed_official 0:51ac1d130fd4 1325 if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
mbed_official 0:51ac1d130fd4 1326 pcb->state = CLOSE_WAIT;
mbed_official 0:51ac1d130fd4 1327 }
mbed_official 0:51ac1d130fd4 1328 }
mbed_official 0:51ac1d130fd4 1329
mbed_official 0:51ac1d130fd4 1330 pcb->ooseq = cseg->next;
mbed_official 0:51ac1d130fd4 1331 tcp_seg_free(cseg);
mbed_official 0:51ac1d130fd4 1332 }
mbed_official 0:51ac1d130fd4 1333 #endif /* TCP_QUEUE_OOSEQ */
mbed_official 0:51ac1d130fd4 1334
mbed_official 0:51ac1d130fd4 1335
mbed_official 0:51ac1d130fd4 1336 /* Acknowledge the segment(s). */
mbed_official 0:51ac1d130fd4 1337 tcp_ack(pcb);
mbed_official 0:51ac1d130fd4 1338
mbed_official 0:51ac1d130fd4 1339 } else {
mbed_official 0:51ac1d130fd4 1340 /* We get here if the incoming segment is out-of-sequence. */
mbed_official 0:51ac1d130fd4 1341 tcp_send_empty_ack(pcb);
mbed_official 0:51ac1d130fd4 1342 #if TCP_QUEUE_OOSEQ
mbed_official 0:51ac1d130fd4 1343 /* We queue the segment on the ->ooseq queue. */
mbed_official 0:51ac1d130fd4 1344 if (pcb->ooseq == NULL) {
mbed_official 0:51ac1d130fd4 1345 pcb->ooseq = tcp_seg_copy(&inseg);
mbed_official 0:51ac1d130fd4 1346 } else {
mbed_official 0:51ac1d130fd4 1347 /* If the queue is not empty, we walk through the queue and
mbed_official 0:51ac1d130fd4 1348 try to find a place where the sequence number of the
mbed_official 0:51ac1d130fd4 1349 incoming segment is between the sequence numbers of the
mbed_official 0:51ac1d130fd4 1350 previous and the next segment on the ->ooseq queue. That is
mbed_official 0:51ac1d130fd4 1351 the place where we put the incoming segment. If needed, we
mbed_official 0:51ac1d130fd4 1352 trim the second edges of the previous and the incoming
mbed_official 0:51ac1d130fd4 1353 segment so that it will fit into the sequence.
mbed_official 0:51ac1d130fd4 1354
mbed_official 0:51ac1d130fd4 1355 If the incoming segment has the same sequence number as a
mbed_official 0:51ac1d130fd4 1356 segment on the ->ooseq queue, we discard the segment that
mbed_official 0:51ac1d130fd4 1357 contains less data. */
mbed_official 0:51ac1d130fd4 1358
mbed_official 0:51ac1d130fd4 1359 prev = NULL;
mbed_official 0:51ac1d130fd4 1360 for(next = pcb->ooseq; next != NULL; next = next->next) {
mbed_official 0:51ac1d130fd4 1361 if (seqno == next->tcphdr->seqno) {
mbed_official 0:51ac1d130fd4 1362 /* The sequence number of the incoming segment is the
mbed_official 0:51ac1d130fd4 1363 same as the sequence number of the segment on
mbed_official 0:51ac1d130fd4 1364 ->ooseq. We check the lengths to see which one to
mbed_official 0:51ac1d130fd4 1365 discard. */
mbed_official 0:51ac1d130fd4 1366 if (inseg.len > next->len) {
mbed_official 0:51ac1d130fd4 1367 /* The incoming segment is larger than the old
mbed_official 0:51ac1d130fd4 1368 segment. We replace some segments with the new
mbed_official 0:51ac1d130fd4 1369 one. */
mbed_official 0:51ac1d130fd4 1370 cseg = tcp_seg_copy(&inseg);
mbed_official 0:51ac1d130fd4 1371 if (cseg != NULL) {
mbed_official 0:51ac1d130fd4 1372 if (prev != NULL) {
mbed_official 0:51ac1d130fd4 1373 prev->next = cseg;
mbed_official 0:51ac1d130fd4 1374 } else {
mbed_official 0:51ac1d130fd4 1375 pcb->ooseq = cseg;
mbed_official 0:51ac1d130fd4 1376 }
mbed_official 0:51ac1d130fd4 1377 tcp_oos_insert_segment(cseg, next);
mbed_official 0:51ac1d130fd4 1378 }
mbed_official 0:51ac1d130fd4 1379 break;
mbed_official 0:51ac1d130fd4 1380 } else {
mbed_official 0:51ac1d130fd4 1381 /* Either the lenghts are the same or the incoming
mbed_official 0:51ac1d130fd4 1382 segment was smaller than the old one; in either
mbed_official 0:51ac1d130fd4 1383 case, we ditch the incoming segment. */
mbed_official 0:51ac1d130fd4 1384 break;
mbed_official 0:51ac1d130fd4 1385 }
mbed_official 0:51ac1d130fd4 1386 } else {
mbed_official 0:51ac1d130fd4 1387 if (prev == NULL) {
mbed_official 0:51ac1d130fd4 1388 if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
mbed_official 0:51ac1d130fd4 1389 /* The sequence number of the incoming segment is lower
mbed_official 0:51ac1d130fd4 1390 than the sequence number of the first segment on the
mbed_official 0:51ac1d130fd4 1391 queue. We put the incoming segment first on the
mbed_official 0:51ac1d130fd4 1392 queue. */
mbed_official 0:51ac1d130fd4 1393 cseg = tcp_seg_copy(&inseg);
mbed_official 0:51ac1d130fd4 1394 if (cseg != NULL) {
mbed_official 0:51ac1d130fd4 1395 pcb->ooseq = cseg;
mbed_official 0:51ac1d130fd4 1396 tcp_oos_insert_segment(cseg, next);
mbed_official 0:51ac1d130fd4 1397 }
mbed_official 0:51ac1d130fd4 1398 break;
mbed_official 0:51ac1d130fd4 1399 }
mbed_official 0:51ac1d130fd4 1400 } else {
mbed_official 0:51ac1d130fd4 1401 /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
mbed_official 0:51ac1d130fd4 1402 TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
mbed_official 0:51ac1d130fd4 1403 if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
mbed_official 0:51ac1d130fd4 1404 /* The sequence number of the incoming segment is in
mbed_official 0:51ac1d130fd4 1405 between the sequence numbers of the previous and
mbed_official 0:51ac1d130fd4 1406 the next segment on ->ooseq. We trim trim the previous
mbed_official 0:51ac1d130fd4 1407 segment, delete next segments that included in received segment
mbed_official 0:51ac1d130fd4 1408 and trim received, if needed. */
mbed_official 0:51ac1d130fd4 1409 cseg = tcp_seg_copy(&inseg);
mbed_official 0:51ac1d130fd4 1410 if (cseg != NULL) {
mbed_official 0:51ac1d130fd4 1411 if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
mbed_official 0:51ac1d130fd4 1412 /* We need to trim the prev segment. */
mbed_official 0:51ac1d130fd4 1413 prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
mbed_official 0:51ac1d130fd4 1414 pbuf_realloc(prev->p, prev->len);
mbed_official 0:51ac1d130fd4 1415 }
mbed_official 0:51ac1d130fd4 1416 prev->next = cseg;
mbed_official 0:51ac1d130fd4 1417 tcp_oos_insert_segment(cseg, next);
mbed_official 0:51ac1d130fd4 1418 }
mbed_official 0:51ac1d130fd4 1419 break;
mbed_official 0:51ac1d130fd4 1420 }
mbed_official 0:51ac1d130fd4 1421 }
mbed_official 0:51ac1d130fd4 1422 /* If the "next" segment is the last segment on the
mbed_official 0:51ac1d130fd4 1423 ooseq queue, we add the incoming segment to the end
mbed_official 0:51ac1d130fd4 1424 of the list. */
mbed_official 0:51ac1d130fd4 1425 if (next->next == NULL &&
mbed_official 0:51ac1d130fd4 1426 TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
mbed_official 0:51ac1d130fd4 1427 if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 1428 /* segment "next" already contains all data */
mbed_official 0:51ac1d130fd4 1429 break;
mbed_official 0:51ac1d130fd4 1430 }
mbed_official 0:51ac1d130fd4 1431 next->next = tcp_seg_copy(&inseg);
mbed_official 0:51ac1d130fd4 1432 if (next->next != NULL) {
mbed_official 0:51ac1d130fd4 1433 if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
mbed_official 0:51ac1d130fd4 1434 /* We need to trim the last segment. */
mbed_official 0:51ac1d130fd4 1435 next->len = (u16_t)(seqno - next->tcphdr->seqno);
mbed_official 0:51ac1d130fd4 1436 pbuf_realloc(next->p, next->len);
mbed_official 0:51ac1d130fd4 1437 }
mbed_official 0:51ac1d130fd4 1438 /* check if the remote side overruns our receive window */
mbed_official 0:51ac1d130fd4 1439 if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
mbed_official 0:51ac1d130fd4 1440 LWIP_DEBUGF(TCP_INPUT_DEBUG,
mbed_official 0:51ac1d130fd4 1441 ("tcp_receive: other end overran receive window"
mbed_official 0:51ac1d130fd4 1442 "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
mbed_official 0:51ac1d130fd4 1443 seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
mbed_official 0:51ac1d130fd4 1444 if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
mbed_official 0:51ac1d130fd4 1445 /* Must remove the FIN from the header as we're trimming
mbed_official 0:51ac1d130fd4 1446 * that byte of sequence-space from the packet */
mbed_official 0:51ac1d130fd4 1447 TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
mbed_official 0:51ac1d130fd4 1448 }
mbed_official 0:51ac1d130fd4 1449 /* Adjust length of segment to fit in the window. */
mbed_official 0:51ac1d130fd4 1450 next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
mbed_official 0:51ac1d130fd4 1451 pbuf_realloc(next->next->p, next->next->len);
mbed_official 0:51ac1d130fd4 1452 tcplen = TCP_TCPLEN(next->next);
mbed_official 0:51ac1d130fd4 1453 LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
mbed_official 0:51ac1d130fd4 1454 (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
mbed_official 0:51ac1d130fd4 1455 }
mbed_official 0:51ac1d130fd4 1456 }
mbed_official 0:51ac1d130fd4 1457 break;
mbed_official 0:51ac1d130fd4 1458 }
mbed_official 0:51ac1d130fd4 1459 }
mbed_official 0:51ac1d130fd4 1460 prev = next;
mbed_official 0:51ac1d130fd4 1461 }
mbed_official 0:51ac1d130fd4 1462 }
mbed_official 0:51ac1d130fd4 1463 #endif /* TCP_QUEUE_OOSEQ */
mbed_official 0:51ac1d130fd4 1464
mbed_official 0:51ac1d130fd4 1465 }
mbed_official 0:51ac1d130fd4 1466 } else {
mbed_official 0:51ac1d130fd4 1467 /* The incoming segment is not withing the window. */
mbed_official 0:51ac1d130fd4 1468 tcp_send_empty_ack(pcb);
mbed_official 0:51ac1d130fd4 1469 }
mbed_official 0:51ac1d130fd4 1470 } else {
mbed_official 0:51ac1d130fd4 1471 /* Segments with length 0 is taken care of here. Segments that
mbed_official 0:51ac1d130fd4 1472 fall out of the window are ACKed. */
mbed_official 0:51ac1d130fd4 1473 /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) ||
mbed_official 0:51ac1d130fd4 1474 TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
mbed_official 0:51ac1d130fd4 1475 if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
mbed_official 0:51ac1d130fd4 1476 tcp_ack_now(pcb);
mbed_official 0:51ac1d130fd4 1477 }
mbed_official 0:51ac1d130fd4 1478 }
mbed_official 0:51ac1d130fd4 1479 }
mbed_official 0:51ac1d130fd4 1480
mbed_official 0:51ac1d130fd4 1481 /**
mbed_official 0:51ac1d130fd4 1482 * Parses the options contained in the incoming segment.
mbed_official 0:51ac1d130fd4 1483 *
mbed_official 0:51ac1d130fd4 1484 * Called from tcp_listen_input() and tcp_process().
mbed_official 0:51ac1d130fd4 1485 * Currently, only the MSS option is supported!
mbed_official 0:51ac1d130fd4 1486 *
mbed_official 0:51ac1d130fd4 1487 * @param pcb the tcp_pcb for which a segment arrived
mbed_official 0:51ac1d130fd4 1488 */
mbed_official 0:51ac1d130fd4 1489 static void
mbed_official 0:51ac1d130fd4 1490 tcp_parseopt(struct tcp_pcb *pcb)
mbed_official 0:51ac1d130fd4 1491 {
mbed_official 0:51ac1d130fd4 1492 u16_t c, max_c;
mbed_official 0:51ac1d130fd4 1493 u16_t mss;
mbed_official 0:51ac1d130fd4 1494 u8_t *opts, opt;
mbed_official 0:51ac1d130fd4 1495 #if LWIP_TCP_TIMESTAMPS
mbed_official 0:51ac1d130fd4 1496 u32_t tsval;
mbed_official 0:51ac1d130fd4 1497 #endif
mbed_official 0:51ac1d130fd4 1498
mbed_official 0:51ac1d130fd4 1499 opts = (u8_t *)tcphdr + TCP_HLEN;
mbed_official 0:51ac1d130fd4 1500
mbed_official 0:51ac1d130fd4 1501 /* Parse the TCP MSS option, if present. */
mbed_official 0:51ac1d130fd4 1502 if(TCPH_HDRLEN(tcphdr) > 0x5) {
mbed_official 0:51ac1d130fd4 1503 max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
mbed_official 0:51ac1d130fd4 1504 for (c = 0; c < max_c; ) {
mbed_official 0:51ac1d130fd4 1505 opt = opts[c];
mbed_official 0:51ac1d130fd4 1506 switch (opt) {
mbed_official 0:51ac1d130fd4 1507 case 0x00:
mbed_official 0:51ac1d130fd4 1508 /* End of options. */
mbed_official 0:51ac1d130fd4 1509 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
mbed_official 0:51ac1d130fd4 1510 return;
mbed_official 0:51ac1d130fd4 1511 case 0x01:
mbed_official 0:51ac1d130fd4 1512 /* NOP option. */
mbed_official 0:51ac1d130fd4 1513 ++c;
mbed_official 0:51ac1d130fd4 1514 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
mbed_official 0:51ac1d130fd4 1515 break;
mbed_official 0:51ac1d130fd4 1516 case 0x02:
mbed_official 0:51ac1d130fd4 1517 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
mbed_official 0:51ac1d130fd4 1518 if (opts[c + 1] != 0x04 || c + 0x04 > max_c) {
mbed_official 0:51ac1d130fd4 1519 /* Bad length */
mbed_official 0:51ac1d130fd4 1520 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
mbed_official 0:51ac1d130fd4 1521 return;
mbed_official 0:51ac1d130fd4 1522 }
mbed_official 0:51ac1d130fd4 1523 /* An MSS option with the right option length. */
mbed_official 0:51ac1d130fd4 1524 mss = (opts[c + 2] << 8) | opts[c + 3];
mbed_official 0:51ac1d130fd4 1525 /* Limit the mss to the configured TCP_MSS and prevent division by zero */
mbed_official 0:51ac1d130fd4 1526 pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
mbed_official 0:51ac1d130fd4 1527 /* Advance to next option */
mbed_official 0:51ac1d130fd4 1528 c += 0x04;
mbed_official 0:51ac1d130fd4 1529 break;
mbed_official 0:51ac1d130fd4 1530 #if LWIP_TCP_TIMESTAMPS
mbed_official 0:51ac1d130fd4 1531 case 0x08:
mbed_official 0:51ac1d130fd4 1532 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
mbed_official 0:51ac1d130fd4 1533 if (opts[c + 1] != 0x0A || c + 0x0A > max_c) {
mbed_official 0:51ac1d130fd4 1534 /* Bad length */
mbed_official 0:51ac1d130fd4 1535 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
mbed_official 0:51ac1d130fd4 1536 return;
mbed_official 0:51ac1d130fd4 1537 }
mbed_official 0:51ac1d130fd4 1538 /* TCP timestamp option with valid length */
mbed_official 0:51ac1d130fd4 1539 tsval = (opts[c+2]) | (opts[c+3] << 8) |
mbed_official 0:51ac1d130fd4 1540 (opts[c+4] << 16) | (opts[c+5] << 24);
mbed_official 0:51ac1d130fd4 1541 if (flags & TCP_SYN) {
mbed_official 0:51ac1d130fd4 1542 pcb->ts_recent = ntohl(tsval);
mbed_official 0:51ac1d130fd4 1543 pcb->flags |= TF_TIMESTAMP;
mbed_official 0:51ac1d130fd4 1544 } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
mbed_official 0:51ac1d130fd4 1545 pcb->ts_recent = ntohl(tsval);
mbed_official 0:51ac1d130fd4 1546 }
mbed_official 0:51ac1d130fd4 1547 /* Advance to next option */
mbed_official 0:51ac1d130fd4 1548 c += 0x0A;
mbed_official 0:51ac1d130fd4 1549 break;
mbed_official 0:51ac1d130fd4 1550 #endif
mbed_official 0:51ac1d130fd4 1551 default:
mbed_official 0:51ac1d130fd4 1552 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
mbed_official 0:51ac1d130fd4 1553 if (opts[c + 1] == 0) {
mbed_official 0:51ac1d130fd4 1554 LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
mbed_official 0:51ac1d130fd4 1555 /* If the length field is zero, the options are malformed
mbed_official 0:51ac1d130fd4 1556 and we don't process them further. */
mbed_official 0:51ac1d130fd4 1557 return;
mbed_official 0:51ac1d130fd4 1558 }
mbed_official 0:51ac1d130fd4 1559 /* All other options have a length field, so that we easily
mbed_official 0:51ac1d130fd4 1560 can skip past them. */
mbed_official 0:51ac1d130fd4 1561 c += opts[c + 1];
mbed_official 0:51ac1d130fd4 1562 }
mbed_official 0:51ac1d130fd4 1563 }
mbed_official 0:51ac1d130fd4 1564 }
mbed_official 0:51ac1d130fd4 1565 }
mbed_official 0:51ac1d130fd4 1566
mbed_official 0:51ac1d130fd4 1567 #endif /* LWIP_TCP */