1 | /**
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2 | * @file
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3 | * Transmission Control Protocol, incoming traffic
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4 | *
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5 | * The input processing functions of the TCP layer.
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6 | *
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7 | * These functions are generally called in the order (ip_input() ->)
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8 | * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
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9 | *
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10 | */
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11 |
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12 | /*
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13 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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14 | * All rights reserved.
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15 | *
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16 | * Redistribution and use in source and binary forms, with or without modification,
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17 | * are permitted provided that the following conditions are met:
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18 | *
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19 | * 1. Redistributions of source code must retain the above copyright notice,
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20 | * this list of conditions and the following disclaimer.
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21 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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22 | * this list of conditions and the following disclaimer in the documentation
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23 | * and/or other materials provided with the distribution.
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24 | * 3. The name of the author may not be used to endorse or promote products
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25 | * derived from this software without specific prior written permission.
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26 | *
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27 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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28 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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29 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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30 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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31 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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32 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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33 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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34 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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35 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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36 | * OF SUCH DAMAGE.
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37 | *
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38 | * This file is part of the lwIP TCP/IP stack.
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39 | *
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40 | * Author: Adam Dunkels <adam@sics.se>
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41 | *
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42 | */
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43 |
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44 | #include "lwip/opt.h"
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45 |
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46 | #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
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47 |
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48 | #include "lwip/tcp_impl.h"
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49 | #include "lwip/def.h"
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50 | #include "lwip/ip_addr.h"
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51 | #include "lwip/netif.h"
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52 | #include "lwip/mem.h"
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53 | #include "lwip/memp.h"
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54 | #include "lwip/inet_chksum.h"
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55 | #include "lwip/stats.h"
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56 | #include "lwip/snmp.h"
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57 | #include "arch/perf.h"
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58 |
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59 | /* These variables are global to all functions involved in the input
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60 | processing of TCP segments. They are set by the tcp_input()
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61 | function. */
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62 | static struct tcp_seg inseg;
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63 | static struct tcp_hdr *tcphdr;
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64 | static struct ip_hdr *iphdr;
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65 | static u32_t seqno, ackno;
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66 | static u8_t flags;
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67 | static u16_t tcplen;
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68 |
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69 | static u8_t recv_flags;
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70 | static struct pbuf *recv_data;
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71 |
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72 | struct tcp_pcb *tcp_input_pcb;
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73 |
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74 | /* Forward declarations. */
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75 | static err_t tcp_process(struct tcp_pcb *pcb);
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76 | static void tcp_receive(struct tcp_pcb *pcb);
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77 | static void tcp_parseopt(struct tcp_pcb *pcb);
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78 |
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79 | static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
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80 | static err_t tcp_timewait_input(struct tcp_pcb *pcb);
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81 |
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82 | /**
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83 | * The initial input processing of TCP. It verifies the TCP header, demultiplexes
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84 | * the segment between the PCBs and passes it on to tcp_process(), which implements
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85 | * the TCP finite state machine. This function is called by the IP layer (in
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86 | * ip_input()).
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87 | *
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88 | * @param p received TCP segment to process (p->payload pointing to the IP header)
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89 | * @param inp network interface on which this segment was received
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90 | */
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91 | void
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92 | tcp_input(struct pbuf *p, struct netif *inp)
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93 | {
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94 | struct tcp_pcb *pcb, *prev;
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95 | struct tcp_pcb_listen *lpcb;
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96 | #if SO_REUSE
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97 | struct tcp_pcb *lpcb_prev = NULL;
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98 | struct tcp_pcb_listen *lpcb_any = NULL;
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99 | #endif /* SO_REUSE */
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100 | u8_t hdrlen;
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101 | err_t err;
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102 |
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103 | PERF_START;
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104 |
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105 | TCP_STATS_INC(tcp.recv);
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106 | snmp_inc_tcpinsegs();
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107 |
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108 | iphdr = (struct ip_hdr *)p->payload;
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109 | tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
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110 |
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111 | #if TCP_INPUT_DEBUG
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112 | tcp_debug_print(tcphdr);
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113 | #endif
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114 |
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115 | /* remove header from payload */
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116 | if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
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117 | /* drop short packets */
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118 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
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119 | TCP_STATS_INC(tcp.lenerr);
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120 | goto dropped;
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121 | }
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122 |
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123 | /* Don't even process incoming broadcasts/multicasts. */
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124 | if (ip_addr_isbroadcast(¤t_iphdr_dest, inp) ||
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125 | ip_addr_ismulticast(¤t_iphdr_dest)) {
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126 | TCP_STATS_INC(tcp.proterr);
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127 | goto dropped;
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128 | }
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129 |
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130 | #if CHECKSUM_CHECK_TCP
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131 | /* Verify TCP checksum. */
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132 | if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
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133 | IP_PROTO_TCP, p->tot_len) != 0) {
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134 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
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135 | inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
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136 | IP_PROTO_TCP, p->tot_len)));
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137 | #if TCP_DEBUG
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138 | tcp_debug_print(tcphdr);
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139 | #endif /* TCP_DEBUG */
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140 | TCP_STATS_INC(tcp.chkerr);
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141 | goto dropped;
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142 | }
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143 | #endif
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144 |
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145 | /* Move the payload pointer in the pbuf so that it points to the
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146 | TCP data instead of the TCP header. */
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147 | hdrlen = TCPH_HDRLEN(tcphdr);
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148 | if(pbuf_header(p, -(hdrlen * 4))){
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149 | /* drop short packets */
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150 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
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151 | TCP_STATS_INC(tcp.lenerr);
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152 | goto dropped;
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153 | }
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154 |
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155 | /* Convert fields in TCP header to host byte order. */
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156 | tcphdr->src = ntohs(tcphdr->src);
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157 | tcphdr->dest = ntohs(tcphdr->dest);
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158 | seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
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159 | ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
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160 | tcphdr->wnd = ntohs(tcphdr->wnd);
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161 |
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162 | flags = TCPH_FLAGS(tcphdr);
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163 | tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);
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164 |
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165 | /* Demultiplex an incoming segment. First, we check if it is destined
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166 | for an active connection. */
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167 | prev = NULL;
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168 |
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169 |
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170 | for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
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171 | LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
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172 | LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
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173 | LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
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174 | if (pcb->remote_port == tcphdr->src &&
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175 | pcb->local_port == tcphdr->dest &&
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176 | ip_addr_cmp(&(pcb->remote_ip), ¤t_iphdr_src) &&
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177 | ip_addr_cmp(&(pcb->local_ip), ¤t_iphdr_dest)) {
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178 |
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179 | /* Move this PCB to the front of the list so that subsequent
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180 | lookups will be faster (we exploit locality in TCP segment
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181 | arrivals). */
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182 | LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
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183 | if (prev != NULL) {
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184 | prev->next = pcb->next;
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185 | pcb->next = tcp_active_pcbs;
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186 | tcp_active_pcbs = pcb;
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187 | }
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188 | LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
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189 | break;
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190 | }
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191 | prev = pcb;
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192 | }
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193 |
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194 | if (pcb == NULL) {
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195 | /* If it did not go to an active connection, we check the connections
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196 | in the TIME-WAIT state. */
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197 | for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
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198 | LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
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199 | if (pcb->remote_port == tcphdr->src &&
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200 | pcb->local_port == tcphdr->dest &&
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201 | ip_addr_cmp(&(pcb->remote_ip), ¤t_iphdr_src) &&
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202 | ip_addr_cmp(&(pcb->local_ip), ¤t_iphdr_dest)) {
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203 | /* We don't really care enough to move this PCB to the front
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204 | of the list since we are not very likely to receive that
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205 | many segments for connections in TIME-WAIT. */
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206 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
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207 | tcp_timewait_input(pcb);
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208 | pbuf_free(p);
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209 | return;
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210 | }
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211 | }
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212 |
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213 | /* Finally, if we still did not get a match, we check all PCBs that
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214 | are LISTENing for incoming connections. */
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215 | prev = NULL;
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216 | for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
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217 | if (lpcb->local_port == tcphdr->dest) {
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218 | #if SO_REUSE
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219 | if (ip_addr_cmp(&(lpcb->local_ip), ¤t_iphdr_dest)) {
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220 | /* found an exact match */
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221 | break;
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222 | } else if(ip_addr_isany(&(lpcb->local_ip))) {
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223 | /* found an ANY-match */
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224 | lpcb_any = lpcb;
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225 | lpcb_prev = prev;
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226 | }
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227 | #else /* SO_REUSE */
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228 | if (ip_addr_cmp(&(lpcb->local_ip), ¤t_iphdr_dest) ||
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229 | ip_addr_isany(&(lpcb->local_ip))) {
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230 | /* found a match */
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231 | break;
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232 | }
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233 | #endif /* SO_REUSE */
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234 | }
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235 | prev = (struct tcp_pcb *)lpcb;
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236 | }
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237 | #if SO_REUSE
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238 | /* first try specific local IP */
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239 | if (lpcb == NULL) {
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240 | /* only pass to ANY if no specific local IP has been found */
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241 | lpcb = lpcb_any;
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242 | prev = lpcb_prev;
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243 | }
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244 | #endif /* SO_REUSE */
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245 | if (lpcb != NULL) {
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246 | /* Move this PCB to the front of the list so that subsequent
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247 | lookups will be faster (we exploit locality in TCP segment
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248 | arrivals). */
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249 | if (prev != NULL) {
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250 | ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
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251 | /* our successor is the remainder of the listening list */
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252 | lpcb->next = tcp_listen_pcbs.listen_pcbs;
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253 | /* put this listening pcb at the head of the listening list */
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254 | tcp_listen_pcbs.listen_pcbs = lpcb;
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255 | }
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256 |
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257 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
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258 | tcp_listen_input(lpcb);
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259 | pbuf_free(p);
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260 | return;
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261 | }
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262 | }
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263 |
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264 | #if TCP_INPUT_DEBUG
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265 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
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266 | tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
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267 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
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268 | #endif /* TCP_INPUT_DEBUG */
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269 |
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270 |
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271 | if (pcb != NULL) {
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272 | /* The incoming segment belongs to a connection. */
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273 | #if TCP_INPUT_DEBUG
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274 | #if TCP_DEBUG
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275 | tcp_debug_print_state(pcb->state);
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276 | #endif /* TCP_DEBUG */
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277 | #endif /* TCP_INPUT_DEBUG */
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278 |
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279 | /* Set up a tcp_seg structure. */
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280 | inseg.next = NULL;
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281 | inseg.len = p->tot_len;
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282 | inseg.p = p;
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283 | inseg.tcphdr = tcphdr;
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284 |
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285 | recv_data = NULL;
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286 | recv_flags = 0;
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287 |
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288 | if (flags & TCP_PSH) {
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289 | p->flags |= PBUF_FLAG_PUSH;
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290 | }
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291 |
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292 | /* If there is data which was previously "refused" by upper layer */
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293 | if (pcb->refused_data != NULL) {
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294 | if ((tcp_process_refused_data(pcb) == ERR_ABRT) ||
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295 | ((pcb->refused_data != NULL) && (tcplen > 0))) {
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296 | /* pcb has been aborted or refused data is still refused and the new
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297 | segment contains data */
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298 | TCP_STATS_INC(tcp.drop);
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299 | snmp_inc_tcpinerrs();
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300 | goto aborted;
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301 | }
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302 | }
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303 | tcp_input_pcb = pcb;
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304 | err = tcp_process(pcb);
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305 | /* A return value of ERR_ABRT means that tcp_abort() was called
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306 | and that the pcb has been freed. If so, we don't do anything. */
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307 | if (err != ERR_ABRT) {
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308 | if (recv_flags & TF_RESET) {
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309 | /* TF_RESET means that the connection was reset by the other
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310 | end. We then call the error callback to inform the
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311 | application that the connection is dead before we
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312 | deallocate the PCB. */
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313 | TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
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314 | tcp_pcb_remove(&tcp_active_pcbs, pcb);
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315 | memp_free(MEMP_TCP_PCB, pcb);
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316 | } else if (recv_flags & TF_CLOSED) {
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317 | /* The connection has been closed and we will deallocate the
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318 | PCB. */
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319 | if (!(pcb->flags & TF_RXCLOSED)) {
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320 | /* Connection closed although the application has only shut down the
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321 | tx side: call the PCB's err callback and indicate the closure to
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322 | ensure the application doesn't continue using the PCB. */
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323 | TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_CLSD);
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324 | }
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325 | tcp_pcb_remove(&tcp_active_pcbs, pcb);
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326 | memp_free(MEMP_TCP_PCB, pcb);
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327 | } else {
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328 | err = ERR_OK;
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329 | /* If the application has registered a "sent" function to be
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330 | called when new send buffer space is available, we call it
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331 | now. */
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332 | if (pcb->acked > 0) {
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333 | TCP_EVENT_SENT(pcb, pcb->acked, err);
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334 | if (err == ERR_ABRT) {
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335 | goto aborted;
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336 | }
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337 | }
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338 |
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339 | if (recv_data != NULL) {
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340 | LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
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341 | if (pcb->flags & TF_RXCLOSED) {
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342 | /* received data although already closed -> abort (send RST) to
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343 | notify the remote host that not all data has been processed */
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344 | pbuf_free(recv_data);
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345 | tcp_abort(pcb);
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346 | goto aborted;
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347 | }
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348 |
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349 | /* Notify application that data has been received. */
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350 | TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
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351 | if (err == ERR_ABRT) {
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352 | goto aborted;
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353 | }
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354 |
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355 | /* If the upper layer can't receive this data, store it */
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356 | if (err != ERR_OK) {
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357 | pcb->refused_data = recv_data;
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358 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
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359 | }
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360 | }
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361 |
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362 | /* If a FIN segment was received, we call the callback
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363 | function with a NULL buffer to indicate EOF. */
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364 | if (recv_flags & TF_GOT_FIN) {
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365 | if (pcb->refused_data != NULL) {
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366 | /* Delay this if we have refused data. */
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367 | pcb->refused_data->flags |= PBUF_FLAG_TCP_FIN;
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368 | } else {
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369 | /* correct rcv_wnd as the application won't call tcp_recved()
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370 | for the FIN's seqno */
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371 | if (pcb->rcv_wnd != TCP_WND) {
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372 | pcb->rcv_wnd++;
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373 | }
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374 | TCP_EVENT_CLOSED(pcb, err);
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375 | if (err == ERR_ABRT) {
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376 | goto aborted;
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377 | }
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378 | }
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379 | }
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380 |
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381 | tcp_input_pcb = NULL;
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382 | /* Try to send something out. */
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383 | tcp_output(pcb);
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384 | #if TCP_INPUT_DEBUG
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385 | #if TCP_DEBUG
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386 | tcp_debug_print_state(pcb->state);
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387 | #endif /* TCP_DEBUG */
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388 | #endif /* TCP_INPUT_DEBUG */
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389 | }
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390 | }
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391 | /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
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392 | Below this line, 'pcb' may not be dereferenced! */
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393 | aborted:
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394 | tcp_input_pcb = NULL;
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395 | recv_data = NULL;
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396 |
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397 | /* give up our reference to inseg.p */
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398 | if (inseg.p != NULL)
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399 | {
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400 | pbuf_free(inseg.p);
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401 | inseg.p = NULL;
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402 | }
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403 | } else {
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404 |
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405 | /* If no matching PCB was found, send a TCP RST (reset) to the
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406 | sender. */
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407 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
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408 | if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
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409 | TCP_STATS_INC(tcp.proterr);
|
---|
410 | TCP_STATS_INC(tcp.drop);
|
---|
411 | tcp_rst(ackno, seqno + tcplen,
|
---|
412 | ip_current_dest_addr(), ip_current_src_addr(),
|
---|
413 | tcphdr->dest, tcphdr->src);
|
---|
414 | }
|
---|
415 | pbuf_free(p);
|
---|
416 | }
|
---|
417 |
|
---|
418 | LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
|
---|
419 | PERF_STOP("tcp_input");
|
---|
420 | return;
|
---|
421 | dropped:
|
---|
422 | TCP_STATS_INC(tcp.drop);
|
---|
423 | snmp_inc_tcpinerrs();
|
---|
424 | pbuf_free(p);
|
---|
425 | }
|
---|
426 |
|
---|
427 | /**
|
---|
428 | * Called by tcp_input() when a segment arrives for a listening
|
---|
429 | * connection (from tcp_input()).
|
---|
430 | *
|
---|
431 | * @param pcb the tcp_pcb_listen for which a segment arrived
|
---|
432 | * @return ERR_OK if the segment was processed
|
---|
433 | * another err_t on error
|
---|
434 | *
|
---|
435 | * @note the return value is not (yet?) used in tcp_input()
|
---|
436 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
437 | * involved is passed as a parameter to this function
|
---|
438 | */
|
---|
439 | static err_t
|
---|
440 | tcp_listen_input(struct tcp_pcb_listen *pcb)
|
---|
441 | {
|
---|
442 | struct tcp_pcb *npcb;
|
---|
443 | err_t rc;
|
---|
444 |
|
---|
445 | if (flags & TCP_RST) {
|
---|
446 | /* An incoming RST should be ignored. Return. */
|
---|
447 | return ERR_OK;
|
---|
448 | }
|
---|
449 |
|
---|
450 | /* In the LISTEN state, we check for incoming SYN segments,
|
---|
451 | creates a new PCB, and responds with a SYN|ACK. */
|
---|
452 | if (flags & TCP_ACK) {
|
---|
453 | /* For incoming segments with the ACK flag set, respond with a
|
---|
454 | RST. */
|
---|
455 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
|
---|
456 | tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
457 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
458 | } else if (flags & TCP_SYN) {
|
---|
459 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
|
---|
460 | #if TCP_LISTEN_BACKLOG
|
---|
461 | if (pcb->accepts_pending >= pcb->backlog) {
|
---|
462 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
|
---|
463 | return ERR_ABRT;
|
---|
464 | }
|
---|
465 | #endif /* TCP_LISTEN_BACKLOG */
|
---|
466 | npcb = tcp_alloc(pcb->prio);
|
---|
467 | /* If a new PCB could not be created (probably due to lack of memory),
|
---|
468 | we don't do anything, but rely on the sender will retransmit the
|
---|
469 | SYN at a time when we have more memory available. */
|
---|
470 | if (npcb == NULL) {
|
---|
471 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
|
---|
472 | TCP_STATS_INC(tcp.memerr);
|
---|
473 | return ERR_MEM;
|
---|
474 | }
|
---|
475 | #if TCP_LISTEN_BACKLOG
|
---|
476 | pcb->accepts_pending++;
|
---|
477 | #endif /* TCP_LISTEN_BACKLOG */
|
---|
478 | /* Set up the new PCB. */
|
---|
479 | ip_addr_copy(npcb->local_ip, current_iphdr_dest);
|
---|
480 | npcb->local_port = pcb->local_port;
|
---|
481 | ip_addr_copy(npcb->remote_ip, current_iphdr_src);
|
---|
482 | npcb->remote_port = tcphdr->src;
|
---|
483 | npcb->state = SYN_RCVD;
|
---|
484 | npcb->rcv_nxt = seqno + 1;
|
---|
485 | npcb->rcv_ann_right_edge = npcb->rcv_nxt;
|
---|
486 | npcb->snd_wnd = tcphdr->wnd;
|
---|
487 | npcb->snd_wnd_max = tcphdr->wnd;
|
---|
488 | npcb->ssthresh = npcb->snd_wnd;
|
---|
489 | npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
|
---|
490 | npcb->callback_arg = pcb->callback_arg;
|
---|
491 | #if LWIP_CALLBACK_API
|
---|
492 | npcb->accept = pcb->accept;
|
---|
493 | #endif /* LWIP_CALLBACK_API */
|
---|
494 | /* inherit socket options */
|
---|
495 | npcb->so_options = pcb->so_options & SOF_INHERITED;
|
---|
496 | /* Register the new PCB so that we can begin receiving segments
|
---|
497 | for it. */
|
---|
498 | TCP_REG_ACTIVE(npcb);
|
---|
499 |
|
---|
500 | /* Parse any options in the SYN. */
|
---|
501 | tcp_parseopt(npcb);
|
---|
502 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
503 | npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
|
---|
504 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
505 |
|
---|
506 | snmp_inc_tcppassiveopens();
|
---|
507 |
|
---|
508 | /* Send a SYN|ACK together with the MSS option. */
|
---|
509 | rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
|
---|
510 | if (rc != ERR_OK) {
|
---|
511 | tcp_abandon(npcb, 0);
|
---|
512 | return rc;
|
---|
513 | }
|
---|
514 | return tcp_output(npcb);
|
---|
515 | }
|
---|
516 | return ERR_OK;
|
---|
517 | }
|
---|
518 |
|
---|
519 | /**
|
---|
520 | * Called by tcp_input() when a segment arrives for a connection in
|
---|
521 | * TIME_WAIT.
|
---|
522 | *
|
---|
523 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
524 | *
|
---|
525 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
526 | * involved is passed as a parameter to this function
|
---|
527 | */
|
---|
528 | static err_t
|
---|
529 | tcp_timewait_input(struct tcp_pcb *pcb)
|
---|
530 | {
|
---|
531 | /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
|
---|
532 | /* RFC 793 3.9 Event Processing - Segment Arrives:
|
---|
533 | * - first check sequence number - we skip that one in TIME_WAIT (always
|
---|
534 | * acceptable since we only send ACKs)
|
---|
535 | * - second check the RST bit (... return) */
|
---|
536 | if (flags & TCP_RST) {
|
---|
537 | return ERR_OK;
|
---|
538 | }
|
---|
539 | /* - fourth, check the SYN bit, */
|
---|
540 | if (flags & TCP_SYN) {
|
---|
541 | /* If an incoming segment is not acceptable, an acknowledgment
|
---|
542 | should be sent in reply */
|
---|
543 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
|
---|
544 | /* If the SYN is in the window it is an error, send a reset */
|
---|
545 | tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
|
---|
546 | tcphdr->dest, tcphdr->src);
|
---|
547 | return ERR_OK;
|
---|
548 | }
|
---|
549 | } else if (flags & TCP_FIN) {
|
---|
550 | /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
|
---|
551 | Restart the 2 MSL time-wait timeout.*/
|
---|
552 | pcb->tmr = tcp_ticks;
|
---|
553 | }
|
---|
554 |
|
---|
555 | if ((tcplen > 0)) {
|
---|
556 | /* Acknowledge data, FIN or out-of-window SYN */
|
---|
557 | pcb->flags |= TF_ACK_NOW;
|
---|
558 | return tcp_output(pcb);
|
---|
559 | }
|
---|
560 | return ERR_OK;
|
---|
561 | }
|
---|
562 |
|
---|
563 | /**
|
---|
564 | * Implements the TCP state machine. Called by tcp_input. In some
|
---|
565 | * states tcp_receive() is called to receive data. The tcp_seg
|
---|
566 | * argument will be freed by the caller (tcp_input()) unless the
|
---|
567 | * recv_data pointer in the pcb is set.
|
---|
568 | *
|
---|
569 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
570 | *
|
---|
571 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
572 | * involved is passed as a parameter to this function
|
---|
573 | */
|
---|
574 | static err_t
|
---|
575 | tcp_process(struct tcp_pcb *pcb)
|
---|
576 | {
|
---|
577 | struct tcp_seg *rseg;
|
---|
578 | u8_t acceptable = 0;
|
---|
579 | err_t err;
|
---|
580 |
|
---|
581 | err = ERR_OK;
|
---|
582 |
|
---|
583 | /* Process incoming RST segments. */
|
---|
584 | if (flags & TCP_RST) {
|
---|
585 | /* First, determine if the reset is acceptable. */
|
---|
586 | if (pcb->state == SYN_SENT) {
|
---|
587 | if (ackno == pcb->snd_nxt) {
|
---|
588 | acceptable = 1;
|
---|
589 | }
|
---|
590 | } else {
|
---|
591 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
---|
592 | pcb->rcv_nxt+pcb->rcv_wnd)) {
|
---|
593 | acceptable = 1;
|
---|
594 | }
|
---|
595 | }
|
---|
596 |
|
---|
597 | if (acceptable) {
|
---|
598 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
|
---|
599 | LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
|
---|
600 | recv_flags |= TF_RESET;
|
---|
601 | pcb->flags &= ~TF_ACK_DELAY;
|
---|
602 | return ERR_RST;
|
---|
603 | } else {
|
---|
604 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
---|
605 | seqno, pcb->rcv_nxt));
|
---|
606 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
---|
607 | seqno, pcb->rcv_nxt));
|
---|
608 | return ERR_OK;
|
---|
609 | }
|
---|
610 | }
|
---|
611 |
|
---|
612 | if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
|
---|
613 | /* Cope with new connection attempt after remote end crashed */
|
---|
614 | tcp_ack_now(pcb);
|
---|
615 | return ERR_OK;
|
---|
616 | }
|
---|
617 |
|
---|
618 | if ((pcb->flags & TF_RXCLOSED) == 0) {
|
---|
619 | /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
|
---|
620 | pcb->tmr = tcp_ticks;
|
---|
621 | }
|
---|
622 | pcb->keep_cnt_sent = 0;
|
---|
623 |
|
---|
624 | tcp_parseopt(pcb);
|
---|
625 |
|
---|
626 | /* Do different things depending on the TCP state. */
|
---|
627 | switch (pcb->state) {
|
---|
628 | case SYN_SENT:
|
---|
629 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
|
---|
630 | pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
|
---|
631 | /* received SYN ACK with expected sequence number? */
|
---|
632 | if ((flags & TCP_ACK) && (flags & TCP_SYN)
|
---|
633 | && ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
|
---|
634 | pcb->snd_buf++;
|
---|
635 | pcb->rcv_nxt = seqno + 1;
|
---|
636 | pcb->rcv_ann_right_edge = pcb->rcv_nxt;
|
---|
637 | pcb->lastack = ackno;
|
---|
638 | pcb->snd_wnd = tcphdr->wnd;
|
---|
639 | pcb->snd_wnd_max = tcphdr->wnd;
|
---|
640 | pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
|
---|
641 | pcb->state = ESTABLISHED;
|
---|
642 |
|
---|
643 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
644 | pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
|
---|
645 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
646 |
|
---|
647 | /* Set ssthresh again after changing pcb->mss (already set in tcp_connect
|
---|
648 | * but for the default value of pcb->mss) */
|
---|
649 | pcb->ssthresh = pcb->mss * 10;
|
---|
650 |
|
---|
651 | pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
|
---|
652 | LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
|
---|
653 | --pcb->snd_queuelen;
|
---|
654 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
|
---|
655 | rseg = pcb->unacked;
|
---|
656 | pcb->unacked = rseg->next;
|
---|
657 | tcp_seg_free(rseg);
|
---|
658 |
|
---|
659 | /* If there's nothing left to acknowledge, stop the retransmit
|
---|
660 | timer, otherwise reset it to start again */
|
---|
661 | if(pcb->unacked == NULL)
|
---|
662 | pcb->rtime = -1;
|
---|
663 | else {
|
---|
664 | pcb->rtime = 0;
|
---|
665 | pcb->nrtx = 0;
|
---|
666 | }
|
---|
667 |
|
---|
668 | /* Call the user specified function to call when sucessfully
|
---|
669 | * connected. */
|
---|
670 | TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
|
---|
671 | if (err == ERR_ABRT) {
|
---|
672 | return ERR_ABRT;
|
---|
673 | }
|
---|
674 | tcp_ack_now(pcb);
|
---|
675 | }
|
---|
676 | /* received ACK? possibly a half-open connection */
|
---|
677 | else if (flags & TCP_ACK) {
|
---|
678 | /* send a RST to bring the other side in a non-synchronized state. */
|
---|
679 | tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
|
---|
680 | tcphdr->dest, tcphdr->src);
|
---|
681 | }
|
---|
682 | break;
|
---|
683 | case SYN_RCVD:
|
---|
684 | if (flags & TCP_ACK) {
|
---|
685 | /* expected ACK number? */
|
---|
686 | if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
|
---|
687 | u16_t old_cwnd;
|
---|
688 | pcb->state = ESTABLISHED;
|
---|
689 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
690 | #if LWIP_CALLBACK_API
|
---|
691 | LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
|
---|
692 | #endif
|
---|
693 | /* Call the accept function. */
|
---|
694 | TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
|
---|
695 | if (err != ERR_OK) {
|
---|
696 | /* If the accept function returns with an error, we abort
|
---|
697 | * the connection. */
|
---|
698 | /* Already aborted? */
|
---|
699 | if (err != ERR_ABRT) {
|
---|
700 | tcp_abort(pcb);
|
---|
701 | }
|
---|
702 | return ERR_ABRT;
|
---|
703 | }
|
---|
704 | old_cwnd = pcb->cwnd;
|
---|
705 | /* If there was any data contained within this ACK,
|
---|
706 | * we'd better pass it on to the application as well. */
|
---|
707 | tcp_receive(pcb);
|
---|
708 |
|
---|
709 | /* Prevent ACK for SYN to generate a sent event */
|
---|
710 | if (pcb->acked != 0) {
|
---|
711 | pcb->acked--;
|
---|
712 | }
|
---|
713 |
|
---|
714 | pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
|
---|
715 |
|
---|
716 | if (recv_flags & TF_GOT_FIN) {
|
---|
717 | tcp_ack_now(pcb);
|
---|
718 | pcb->state = CLOSE_WAIT;
|
---|
719 | }
|
---|
720 | } else {
|
---|
721 | /* incorrect ACK number, send RST */
|
---|
722 | tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
|
---|
723 | tcphdr->dest, tcphdr->src);
|
---|
724 | }
|
---|
725 | } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
|
---|
726 | /* Looks like another copy of the SYN - retransmit our SYN-ACK */
|
---|
727 | tcp_rexmit(pcb);
|
---|
728 | }
|
---|
729 | break;
|
---|
730 | case CLOSE_WAIT:
|
---|
731 | /* FALLTHROUGH */
|
---|
732 | case ESTABLISHED:
|
---|
733 | tcp_receive(pcb);
|
---|
734 | if (recv_flags & TF_GOT_FIN) { /* passive close */
|
---|
735 | tcp_ack_now(pcb);
|
---|
736 | pcb->state = CLOSE_WAIT;
|
---|
737 | }
|
---|
738 | break;
|
---|
739 | case FIN_WAIT_1:
|
---|
740 | tcp_receive(pcb);
|
---|
741 | if (recv_flags & TF_GOT_FIN) {
|
---|
742 | if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
|
---|
743 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
744 | ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
745 | tcp_ack_now(pcb);
|
---|
746 | tcp_pcb_purge(pcb);
|
---|
747 | TCP_RMV_ACTIVE(pcb);
|
---|
748 | pcb->state = TIME_WAIT;
|
---|
749 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
750 | } else {
|
---|
751 | tcp_ack_now(pcb);
|
---|
752 | pcb->state = CLOSING;
|
---|
753 | }
|
---|
754 | } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
|
---|
755 | pcb->state = FIN_WAIT_2;
|
---|
756 | }
|
---|
757 | break;
|
---|
758 | case FIN_WAIT_2:
|
---|
759 | tcp_receive(pcb);
|
---|
760 | if (recv_flags & TF_GOT_FIN) {
|
---|
761 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
762 | tcp_ack_now(pcb);
|
---|
763 | tcp_pcb_purge(pcb);
|
---|
764 | TCP_RMV_ACTIVE(pcb);
|
---|
765 | pcb->state = TIME_WAIT;
|
---|
766 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
767 | }
|
---|
768 | break;
|
---|
769 | case CLOSING:
|
---|
770 | tcp_receive(pcb);
|
---|
771 | if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
|
---|
772 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
773 | tcp_pcb_purge(pcb);
|
---|
774 | TCP_RMV_ACTIVE(pcb);
|
---|
775 | pcb->state = TIME_WAIT;
|
---|
776 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
777 | }
|
---|
778 | break;
|
---|
779 | case LAST_ACK:
|
---|
780 | tcp_receive(pcb);
|
---|
781 | if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
|
---|
782 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
783 | /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
|
---|
784 | recv_flags |= TF_CLOSED;
|
---|
785 | }
|
---|
786 | break;
|
---|
787 | default:
|
---|
788 | break;
|
---|
789 | }
|
---|
790 | return ERR_OK;
|
---|
791 | }
|
---|
792 |
|
---|
793 | #if TCP_QUEUE_OOSEQ
|
---|
794 | /**
|
---|
795 | * Insert segment into the list (segments covered with new one will be deleted)
|
---|
796 | *
|
---|
797 | * Called from tcp_receive()
|
---|
798 | */
|
---|
799 | static void
|
---|
800 | tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
|
---|
801 | {
|
---|
802 | struct tcp_seg *old_seg;
|
---|
803 |
|
---|
804 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
---|
805 | /* received segment overlaps all following segments */
|
---|
806 | tcp_segs_free(next);
|
---|
807 | next = NULL;
|
---|
808 | }
|
---|
809 | else {
|
---|
810 | /* delete some following segments
|
---|
811 | oos queue may have segments with FIN flag */
|
---|
812 | while (next &&
|
---|
813 | TCP_SEQ_GEQ((seqno + cseg->len),
|
---|
814 | (next->tcphdr->seqno + next->len))) {
|
---|
815 | /* cseg with FIN already processed */
|
---|
816 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
---|
817 | TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
|
---|
818 | }
|
---|
819 | old_seg = next;
|
---|
820 | next = next->next;
|
---|
821 | tcp_seg_free(old_seg);
|
---|
822 | }
|
---|
823 | if (next &&
|
---|
824 | TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
|
---|
825 | /* We need to trim the incoming segment. */
|
---|
826 | cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
|
---|
827 | pbuf_realloc(cseg->p, cseg->len);
|
---|
828 | }
|
---|
829 | }
|
---|
830 | cseg->next = next;
|
---|
831 | }
|
---|
832 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
833 |
|
---|
834 | /**
|
---|
835 | * Called by tcp_process. Checks if the given segment is an ACK for outstanding
|
---|
836 | * data, and if so frees the memory of the buffered data. Next, is places the
|
---|
837 | * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
|
---|
838 | * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
|
---|
839 | * it has been removed from the buffer.
|
---|
840 | *
|
---|
841 | * If the incoming segment constitutes an ACK for a segment that was used for RTT
|
---|
842 | * estimation, the RTT is estimated here as well.
|
---|
843 | *
|
---|
844 | * Called from tcp_process().
|
---|
845 | */
|
---|
846 | static void
|
---|
847 | tcp_receive(struct tcp_pcb *pcb)
|
---|
848 | {
|
---|
849 | struct tcp_seg *next;
|
---|
850 | #if TCP_QUEUE_OOSEQ
|
---|
851 | struct tcp_seg *prev, *cseg;
|
---|
852 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
853 | struct pbuf *p;
|
---|
854 | s32_t off;
|
---|
855 | s16_t m;
|
---|
856 | u32_t right_wnd_edge;
|
---|
857 | u16_t new_tot_len;
|
---|
858 | int found_dupack = 0;
|
---|
859 | #if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
|
---|
860 | u32_t ooseq_blen;
|
---|
861 | u16_t ooseq_qlen;
|
---|
862 | #endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
|
---|
863 |
|
---|
864 | LWIP_ASSERT("tcp_receive: wrong state", pcb->state >= ESTABLISHED);
|
---|
865 |
|
---|
866 | if (flags & TCP_ACK) {
|
---|
867 | right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
|
---|
868 |
|
---|
869 | /* Update window. */
|
---|
870 | if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
|
---|
871 | (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
|
---|
872 | (pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
|
---|
873 | pcb->snd_wnd = tcphdr->wnd;
|
---|
874 | /* keep track of the biggest window announced by the remote host to calculate
|
---|
875 | the maximum segment size */
|
---|
876 | if (pcb->snd_wnd_max < tcphdr->wnd) {
|
---|
877 | pcb->snd_wnd_max = tcphdr->wnd;
|
---|
878 | }
|
---|
879 | pcb->snd_wl1 = seqno;
|
---|
880 | pcb->snd_wl2 = ackno;
|
---|
881 | if (pcb->snd_wnd == 0) {
|
---|
882 | if (pcb->persist_backoff == 0) {
|
---|
883 | /* start persist timer */
|
---|
884 | pcb->persist_cnt = 0;
|
---|
885 | pcb->persist_backoff = 1;
|
---|
886 | }
|
---|
887 | } else if (pcb->persist_backoff > 0) {
|
---|
888 | /* stop persist timer */
|
---|
889 | pcb->persist_backoff = 0;
|
---|
890 | }
|
---|
891 | LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
|
---|
892 | #if TCP_WND_DEBUG
|
---|
893 | } else {
|
---|
894 | if (pcb->snd_wnd != tcphdr->wnd) {
|
---|
895 | LWIP_DEBUGF(TCP_WND_DEBUG,
|
---|
896 | ("tcp_receive: no window update lastack %"U32_F" ackno %"
|
---|
897 | U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
|
---|
898 | pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
|
---|
899 | }
|
---|
900 | #endif /* TCP_WND_DEBUG */
|
---|
901 | }
|
---|
902 |
|
---|
903 | /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
|
---|
904 | * duplicate ack if:
|
---|
905 | * 1) It doesn't ACK new data
|
---|
906 | * 2) length of received packet is zero (i.e. no payload)
|
---|
907 | * 3) the advertised window hasn't changed
|
---|
908 | * 4) There is outstanding unacknowledged data (retransmission timer running)
|
---|
909 | * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
|
---|
910 | *
|
---|
911 | * If it passes all five, should process as a dupack:
|
---|
912 | * a) dupacks < 3: do nothing
|
---|
913 | * b) dupacks == 3: fast retransmit
|
---|
914 | * c) dupacks > 3: increase cwnd
|
---|
915 | *
|
---|
916 | * If it only passes 1-3, should reset dupack counter (and add to
|
---|
917 | * stats, which we don't do in lwIP)
|
---|
918 | *
|
---|
919 | * If it only passes 1, should reset dupack counter
|
---|
920 | *
|
---|
921 | */
|
---|
922 |
|
---|
923 | /* Clause 1 */
|
---|
924 | if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
|
---|
925 | pcb->acked = 0;
|
---|
926 | /* Clause 2 */
|
---|
927 | if (tcplen == 0) {
|
---|
928 | /* Clause 3 */
|
---|
929 | if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
|
---|
930 | /* Clause 4 */
|
---|
931 | if (pcb->rtime >= 0) {
|
---|
932 | /* Clause 5 */
|
---|
933 | if (pcb->lastack == ackno) {
|
---|
934 | found_dupack = 1;
|
---|
935 | if ((u8_t)(pcb->dupacks + 1) > pcb->dupacks) {
|
---|
936 | ++pcb->dupacks;
|
---|
937 | }
|
---|
938 | if (pcb->dupacks > 3) {
|
---|
939 | /* Inflate the congestion window, but not if it means that
|
---|
940 | the value overflows. */
|
---|
941 | if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
|
---|
942 | pcb->cwnd += pcb->mss;
|
---|
943 | }
|
---|
944 | } else if (pcb->dupacks == 3) {
|
---|
945 | /* Do fast retransmit */
|
---|
946 | tcp_rexmit_fast(pcb);
|
---|
947 | }
|
---|
948 | }
|
---|
949 | }
|
---|
950 | }
|
---|
951 | }
|
---|
952 | /* If Clause (1) or more is true, but not a duplicate ack, reset
|
---|
953 | * count of consecutive duplicate acks */
|
---|
954 | if (!found_dupack) {
|
---|
955 | pcb->dupacks = 0;
|
---|
956 | }
|
---|
957 | } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
|
---|
958 | /* We come here when the ACK acknowledges new data. */
|
---|
959 |
|
---|
960 | /* Reset the "IN Fast Retransmit" flag, since we are no longer
|
---|
961 | in fast retransmit. Also reset the congestion window to the
|
---|
962 | slow start threshold. */
|
---|
963 | if (pcb->flags & TF_INFR) {
|
---|
964 | pcb->flags &= ~TF_INFR;
|
---|
965 | pcb->cwnd = pcb->ssthresh;
|
---|
966 | }
|
---|
967 |
|
---|
968 | /* Reset the number of retransmissions. */
|
---|
969 | pcb->nrtx = 0;
|
---|
970 |
|
---|
971 | /* Reset the retransmission time-out. */
|
---|
972 | pcb->rto = (pcb->sa >> 3) + pcb->sv;
|
---|
973 |
|
---|
974 | /* Update the send buffer space. Diff between the two can never exceed 64K? */
|
---|
975 | pcb->acked = (u16_t)(ackno - pcb->lastack);
|
---|
976 |
|
---|
977 | pcb->snd_buf += pcb->acked;
|
---|
978 |
|
---|
979 | /* Reset the fast retransmit variables. */
|
---|
980 | pcb->dupacks = 0;
|
---|
981 | pcb->lastack = ackno;
|
---|
982 |
|
---|
983 | /* Update the congestion control variables (cwnd and
|
---|
984 | ssthresh). */
|
---|
985 | if (pcb->state >= ESTABLISHED) {
|
---|
986 | if (pcb->cwnd < pcb->ssthresh) {
|
---|
987 | if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
|
---|
988 | pcb->cwnd += pcb->mss;
|
---|
989 | }
|
---|
990 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
|
---|
991 | } else {
|
---|
992 | u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
|
---|
993 | if (new_cwnd > pcb->cwnd) {
|
---|
994 | pcb->cwnd = new_cwnd;
|
---|
995 | }
|
---|
996 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
|
---|
997 | }
|
---|
998 | }
|
---|
999 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
|
---|
1000 | ackno,
|
---|
1001 | pcb->unacked != NULL?
|
---|
1002 | ntohl(pcb->unacked->tcphdr->seqno): 0,
|
---|
1003 | pcb->unacked != NULL?
|
---|
1004 | ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
|
---|
1005 |
|
---|
1006 | /* Remove segment from the unacknowledged list if the incoming
|
---|
1007 | ACK acknowlegdes them. */
|
---|
1008 | while (pcb->unacked != NULL &&
|
---|
1009 | TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
|
---|
1010 | TCP_TCPLEN(pcb->unacked), ackno)) {
|
---|
1011 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
|
---|
1012 | ntohl(pcb->unacked->tcphdr->seqno),
|
---|
1013 | ntohl(pcb->unacked->tcphdr->seqno) +
|
---|
1014 | TCP_TCPLEN(pcb->unacked)));
|
---|
1015 |
|
---|
1016 | next = pcb->unacked;
|
---|
1017 | pcb->unacked = pcb->unacked->next;
|
---|
1018 |
|
---|
1019 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
|
---|
1020 | LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
|
---|
1021 | /* Prevent ACK for FIN to generate a sent event */
|
---|
1022 | if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
|
---|
1023 | pcb->acked--;
|
---|
1024 | }
|
---|
1025 |
|
---|
1026 | pcb->snd_queuelen -= pbuf_clen(next->p);
|
---|
1027 | tcp_seg_free(next);
|
---|
1028 |
|
---|
1029 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
|
---|
1030 | if (pcb->snd_queuelen != 0) {
|
---|
1031 | LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
|
---|
1032 | pcb->unsent != NULL);
|
---|
1033 | }
|
---|
1034 | }
|
---|
1035 |
|
---|
1036 | /* If there's nothing left to acknowledge, stop the retransmit
|
---|
1037 | timer, otherwise reset it to start again */
|
---|
1038 | if(pcb->unacked == NULL)
|
---|
1039 | pcb->rtime = -1;
|
---|
1040 | else
|
---|
1041 | pcb->rtime = 0;
|
---|
1042 |
|
---|
1043 | pcb->polltmr = 0;
|
---|
1044 | } else {
|
---|
1045 | /* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
|
---|
1046 | pcb->acked = 0;
|
---|
1047 | }
|
---|
1048 |
|
---|
1049 | /* We go through the ->unsent list to see if any of the segments
|
---|
1050 | on the list are acknowledged by the ACK. This may seem
|
---|
1051 | strange since an "unsent" segment shouldn't be acked. The
|
---|
1052 | rationale is that lwIP puts all outstanding segments on the
|
---|
1053 | ->unsent list after a retransmission, so these segments may
|
---|
1054 | in fact have been sent once. */
|
---|
1055 | while (pcb->unsent != NULL &&
|
---|
1056 | TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
|
---|
1057 | TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
|
---|
1058 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
|
---|
1059 | ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
|
---|
1060 | TCP_TCPLEN(pcb->unsent)));
|
---|
1061 |
|
---|
1062 | next = pcb->unsent;
|
---|
1063 | pcb->unsent = pcb->unsent->next;
|
---|
1064 | #if TCP_OVERSIZE
|
---|
1065 | if (pcb->unsent == NULL) {
|
---|
1066 | pcb->unsent_oversize = 0;
|
---|
1067 | }
|
---|
1068 | #endif /* TCP_OVERSIZE */
|
---|
1069 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
|
---|
1070 | LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
|
---|
1071 | /* Prevent ACK for FIN to generate a sent event */
|
---|
1072 | if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
|
---|
1073 | pcb->acked--;
|
---|
1074 | }
|
---|
1075 | pcb->snd_queuelen -= pbuf_clen(next->p);
|
---|
1076 | tcp_seg_free(next);
|
---|
1077 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
|
---|
1078 | if (pcb->snd_queuelen != 0) {
|
---|
1079 | LWIP_ASSERT("tcp_receive: valid queue length",
|
---|
1080 | pcb->unacked != NULL || pcb->unsent != NULL);
|
---|
1081 | }
|
---|
1082 | }
|
---|
1083 | /* End of ACK for new data processing. */
|
---|
1084 |
|
---|
1085 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
|
---|
1086 | pcb->rttest, pcb->rtseq, ackno));
|
---|
1087 |
|
---|
1088 | /* RTT estimation calculations. This is done by checking if the
|
---|
1089 | incoming segment acknowledges the segment we use to take a
|
---|
1090 | round-trip time measurement. */
|
---|
1091 | if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
|
---|
1092 | /* diff between this shouldn't exceed 32K since this are tcp timer ticks
|
---|
1093 | and a round-trip shouldn't be that long... */
|
---|
1094 | m = (s16_t)(tcp_ticks - pcb->rttest);
|
---|
1095 |
|
---|
1096 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
|
---|
1097 | m, m * TCP_SLOW_INTERVAL));
|
---|
1098 |
|
---|
1099 | /* This is taken directly from VJs original code in his paper */
|
---|
1100 | m = m - (pcb->sa >> 3);
|
---|
1101 | pcb->sa += m;
|
---|
1102 | if (m < 0) {
|
---|
1103 | m = -m;
|
---|
1104 | }
|
---|
1105 | m = m - (pcb->sv >> 2);
|
---|
1106 | pcb->sv += m;
|
---|
1107 | pcb->rto = (pcb->sa >> 3) + pcb->sv;
|
---|
1108 |
|
---|
1109 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
|
---|
1110 | pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
|
---|
1111 |
|
---|
1112 | pcb->rttest = 0;
|
---|
1113 | }
|
---|
1114 | }
|
---|
1115 |
|
---|
1116 | /* If the incoming segment contains data, we must process it
|
---|
1117 | further unless the pcb already received a FIN.
|
---|
1118 | (RFC 793, chapeter 3.9, "SEGMENT ARRIVES" in states CLOSE-WAIT, CLOSING,
|
---|
1119 | LAST-ACK and TIME-WAIT: "Ignore the segment text.") */
|
---|
1120 | if ((tcplen > 0) && (pcb->state < CLOSE_WAIT)) {
|
---|
1121 | /* This code basically does three things:
|
---|
1122 |
|
---|
1123 | +) If the incoming segment contains data that is the next
|
---|
1124 | in-sequence data, this data is passed to the application. This
|
---|
1125 | might involve trimming the first edge of the data. The rcv_nxt
|
---|
1126 | variable and the advertised window are adjusted.
|
---|
1127 |
|
---|
1128 | +) If the incoming segment has data that is above the next
|
---|
1129 | sequence number expected (->rcv_nxt), the segment is placed on
|
---|
1130 | the ->ooseq queue. This is done by finding the appropriate
|
---|
1131 | place in the ->ooseq queue (which is ordered by sequence
|
---|
1132 | number) and trim the segment in both ends if needed. An
|
---|
1133 | immediate ACK is sent to indicate that we received an
|
---|
1134 | out-of-sequence segment.
|
---|
1135 |
|
---|
1136 | +) Finally, we check if the first segment on the ->ooseq queue
|
---|
1137 | now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
|
---|
1138 | rcv_nxt > ooseq->seqno, we must trim the first edge of the
|
---|
1139 | segment on ->ooseq before we adjust rcv_nxt. The data in the
|
---|
1140 | segments that are now on sequence are chained onto the
|
---|
1141 | incoming segment so that we only need to call the application
|
---|
1142 | once.
|
---|
1143 | */
|
---|
1144 |
|
---|
1145 | /* First, we check if we must trim the first edge. We have to do
|
---|
1146 | this if the sequence number of the incoming segment is less
|
---|
1147 | than rcv_nxt, and the sequence number plus the length of the
|
---|
1148 | segment is larger than rcv_nxt. */
|
---|
1149 | /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
|
---|
1150 | if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
|
---|
1151 | if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
|
---|
1152 | /* Trimming the first edge is done by pushing the payload
|
---|
1153 | pointer in the pbuf downwards. This is somewhat tricky since
|
---|
1154 | we do not want to discard the full contents of the pbuf up to
|
---|
1155 | the new starting point of the data since we have to keep the
|
---|
1156 | TCP header which is present in the first pbuf in the chain.
|
---|
1157 |
|
---|
1158 | What is done is really quite a nasty hack: the first pbuf in
|
---|
1159 | the pbuf chain is pointed to by inseg.p. Since we need to be
|
---|
1160 | able to deallocate the whole pbuf, we cannot change this
|
---|
1161 | inseg.p pointer to point to any of the later pbufs in the
|
---|
1162 | chain. Instead, we point the ->payload pointer in the first
|
---|
1163 | pbuf to data in one of the later pbufs. We also set the
|
---|
1164 | inseg.data pointer to point to the right place. This way, the
|
---|
1165 | ->p pointer will still point to the first pbuf, but the
|
---|
1166 | ->p->payload pointer will point to data in another pbuf.
|
---|
1167 |
|
---|
1168 | After we are done with adjusting the pbuf pointers we must
|
---|
1169 | adjust the ->data pointer in the seg and the segment
|
---|
1170 | length.*/
|
---|
1171 |
|
---|
1172 | off = pcb->rcv_nxt - seqno;
|
---|
1173 | p = inseg.p;
|
---|
1174 | LWIP_ASSERT("inseg.p != NULL", inseg.p);
|
---|
1175 | LWIP_ASSERT("insane offset!", (off < 0x7fff));
|
---|
1176 | if (inseg.p->len < off) {
|
---|
1177 | LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
|
---|
1178 | new_tot_len = (u16_t)(inseg.p->tot_len - off);
|
---|
1179 | while (p->len < off) {
|
---|
1180 | off -= p->len;
|
---|
1181 | /* KJM following line changed (with addition of new_tot_len var)
|
---|
1182 | to fix bug #9076
|
---|
1183 | inseg.p->tot_len -= p->len; */
|
---|
1184 | p->tot_len = new_tot_len;
|
---|
1185 | p->len = 0;
|
---|
1186 | p = p->next;
|
---|
1187 | }
|
---|
1188 | if(pbuf_header(p, (s16_t)-off)) {
|
---|
1189 | /* Do we need to cope with this failing? Assert for now */
|
---|
1190 | LWIP_ASSERT("pbuf_header failed", 0);
|
---|
1191 | }
|
---|
1192 | } else {
|
---|
1193 | if(pbuf_header(inseg.p, (s16_t)-off)) {
|
---|
1194 | /* Do we need to cope with this failing? Assert for now */
|
---|
1195 | LWIP_ASSERT("pbuf_header failed", 0);
|
---|
1196 | }
|
---|
1197 | }
|
---|
1198 | inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
|
---|
1199 | inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
|
---|
1200 | }
|
---|
1201 | else {
|
---|
1202 | if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
|
---|
1203 | /* the whole segment is < rcv_nxt */
|
---|
1204 | /* must be a duplicate of a packet that has already been correctly handled */
|
---|
1205 |
|
---|
1206 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
|
---|
1207 | tcp_ack_now(pcb);
|
---|
1208 | }
|
---|
1209 | }
|
---|
1210 |
|
---|
1211 | /* The sequence number must be within the window (above rcv_nxt
|
---|
1212 | and below rcv_nxt + rcv_wnd) in order to be further
|
---|
1213 | processed. */
|
---|
1214 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
---|
1215 | pcb->rcv_nxt + pcb->rcv_wnd - 1)){
|
---|
1216 | if (pcb->rcv_nxt == seqno) {
|
---|
1217 | /* The incoming segment is the next in sequence. We check if
|
---|
1218 | we have to trim the end of the segment and update rcv_nxt
|
---|
1219 | and pass the data to the application. */
|
---|
1220 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1221 |
|
---|
1222 | if (tcplen > pcb->rcv_wnd) {
|
---|
1223 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
1224 | ("tcp_receive: other end overran receive window"
|
---|
1225 | "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
|
---|
1226 | seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1227 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
1228 | /* Must remove the FIN from the header as we're trimming
|
---|
1229 | * that byte of sequence-space from the packet */
|
---|
1230 | TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
|
---|
1231 | }
|
---|
1232 | /* Adjust length of segment to fit in the window. */
|
---|
1233 | inseg.len = pcb->rcv_wnd;
|
---|
1234 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
---|
1235 | inseg.len -= 1;
|
---|
1236 | }
|
---|
1237 | pbuf_realloc(inseg.p, inseg.len);
|
---|
1238 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1239 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
---|
1240 | (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1241 | }
|
---|
1242 | #if TCP_QUEUE_OOSEQ
|
---|
1243 | /* Received in-sequence data, adjust ooseq data if:
|
---|
1244 | - FIN has been received or
|
---|
1245 | - inseq overlaps with ooseq */
|
---|
1246 | if (pcb->ooseq != NULL) {
|
---|
1247 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
1248 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
1249 | ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
|
---|
1250 | /* Received in-order FIN means anything that was received
|
---|
1251 | * out of order must now have been received in-order, so
|
---|
1252 | * bin the ooseq queue */
|
---|
1253 | while (pcb->ooseq != NULL) {
|
---|
1254 | struct tcp_seg *old_ooseq = pcb->ooseq;
|
---|
1255 | pcb->ooseq = pcb->ooseq->next;
|
---|
1256 | tcp_seg_free(old_ooseq);
|
---|
1257 | }
|
---|
1258 | } else {
|
---|
1259 | next = pcb->ooseq;
|
---|
1260 | /* Remove all segments on ooseq that are covered by inseg already.
|
---|
1261 | * FIN is copied from ooseq to inseg if present. */
|
---|
1262 | while (next &&
|
---|
1263 | TCP_SEQ_GEQ(seqno + tcplen,
|
---|
1264 | next->tcphdr->seqno + next->len)) {
|
---|
1265 | /* inseg cannot have FIN here (already processed above) */
|
---|
1266 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
|
---|
1267 | (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
|
---|
1268 | TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
|
---|
1269 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1270 | }
|
---|
1271 | prev = next;
|
---|
1272 | next = next->next;
|
---|
1273 | tcp_seg_free(prev);
|
---|
1274 | }
|
---|
1275 | /* Now trim right side of inseg if it overlaps with the first
|
---|
1276 | * segment on ooseq */
|
---|
1277 | if (next &&
|
---|
1278 | TCP_SEQ_GT(seqno + tcplen,
|
---|
1279 | next->tcphdr->seqno)) {
|
---|
1280 | /* inseg cannot have FIN here (already processed above) */
|
---|
1281 | inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
|
---|
1282 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
---|
1283 | inseg.len -= 1;
|
---|
1284 | }
|
---|
1285 | pbuf_realloc(inseg.p, inseg.len);
|
---|
1286 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1287 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
|
---|
1288 | (seqno + tcplen) == next->tcphdr->seqno);
|
---|
1289 | }
|
---|
1290 | pcb->ooseq = next;
|
---|
1291 | }
|
---|
1292 | }
|
---|
1293 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1294 |
|
---|
1295 | pcb->rcv_nxt = seqno + tcplen;
|
---|
1296 |
|
---|
1297 | /* Update the receiver's (our) window. */
|
---|
1298 | LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
|
---|
1299 | pcb->rcv_wnd -= tcplen;
|
---|
1300 |
|
---|
1301 | tcp_update_rcv_ann_wnd(pcb);
|
---|
1302 |
|
---|
1303 | /* If there is data in the segment, we make preparations to
|
---|
1304 | pass this up to the application. The ->recv_data variable
|
---|
1305 | is used for holding the pbuf that goes to the
|
---|
1306 | application. The code for reassembling out-of-sequence data
|
---|
1307 | chains its data on this pbuf as well.
|
---|
1308 |
|
---|
1309 | If the segment was a FIN, we set the TF_GOT_FIN flag that will
|
---|
1310 | be used to indicate to the application that the remote side has
|
---|
1311 | closed its end of the connection. */
|
---|
1312 | if (inseg.p->tot_len > 0) {
|
---|
1313 | recv_data = inseg.p;
|
---|
1314 | /* Since this pbuf now is the responsibility of the
|
---|
1315 | application, we delete our reference to it so that we won't
|
---|
1316 | (mistakingly) deallocate it. */
|
---|
1317 | inseg.p = NULL;
|
---|
1318 | }
|
---|
1319 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
1320 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
|
---|
1321 | recv_flags |= TF_GOT_FIN;
|
---|
1322 | }
|
---|
1323 |
|
---|
1324 | #if TCP_QUEUE_OOSEQ
|
---|
1325 | /* We now check if we have segments on the ->ooseq queue that
|
---|
1326 | are now in sequence. */
|
---|
1327 | while (pcb->ooseq != NULL &&
|
---|
1328 | pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
|
---|
1329 |
|
---|
1330 | cseg = pcb->ooseq;
|
---|
1331 | seqno = pcb->ooseq->tcphdr->seqno;
|
---|
1332 |
|
---|
1333 | pcb->rcv_nxt += TCP_TCPLEN(cseg);
|
---|
1334 | LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
|
---|
1335 | pcb->rcv_wnd >= TCP_TCPLEN(cseg));
|
---|
1336 | pcb->rcv_wnd -= TCP_TCPLEN(cseg);
|
---|
1337 |
|
---|
1338 | tcp_update_rcv_ann_wnd(pcb);
|
---|
1339 |
|
---|
1340 | if (cseg->p->tot_len > 0) {
|
---|
1341 | /* Chain this pbuf onto the pbuf that we will pass to
|
---|
1342 | the application. */
|
---|
1343 | if (recv_data) {
|
---|
1344 | pbuf_cat(recv_data, cseg->p);
|
---|
1345 | } else {
|
---|
1346 | recv_data = cseg->p;
|
---|
1347 | }
|
---|
1348 | cseg->p = NULL;
|
---|
1349 | }
|
---|
1350 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
---|
1351 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
|
---|
1352 | recv_flags |= TF_GOT_FIN;
|
---|
1353 | if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
|
---|
1354 | pcb->state = CLOSE_WAIT;
|
---|
1355 | }
|
---|
1356 | }
|
---|
1357 |
|
---|
1358 | pcb->ooseq = cseg->next;
|
---|
1359 | tcp_seg_free(cseg);
|
---|
1360 | }
|
---|
1361 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1362 |
|
---|
1363 |
|
---|
1364 | /* Acknowledge the segment(s). */
|
---|
1365 | tcp_ack(pcb);
|
---|
1366 |
|
---|
1367 | } else {
|
---|
1368 | /* We get here if the incoming segment is out-of-sequence. */
|
---|
1369 | tcp_send_empty_ack(pcb);
|
---|
1370 | #if TCP_QUEUE_OOSEQ
|
---|
1371 | /* We queue the segment on the ->ooseq queue. */
|
---|
1372 | if (pcb->ooseq == NULL) {
|
---|
1373 | pcb->ooseq = tcp_seg_copy(&inseg);
|
---|
1374 | } else {
|
---|
1375 | /* If the queue is not empty, we walk through the queue and
|
---|
1376 | try to find a place where the sequence number of the
|
---|
1377 | incoming segment is between the sequence numbers of the
|
---|
1378 | previous and the next segment on the ->ooseq queue. That is
|
---|
1379 | the place where we put the incoming segment. If needed, we
|
---|
1380 | trim the second edges of the previous and the incoming
|
---|
1381 | segment so that it will fit into the sequence.
|
---|
1382 |
|
---|
1383 | If the incoming segment has the same sequence number as a
|
---|
1384 | segment on the ->ooseq queue, we discard the segment that
|
---|
1385 | contains less data. */
|
---|
1386 |
|
---|
1387 | prev = NULL;
|
---|
1388 | for(next = pcb->ooseq; next != NULL; next = next->next) {
|
---|
1389 | if (seqno == next->tcphdr->seqno) {
|
---|
1390 | /* The sequence number of the incoming segment is the
|
---|
1391 | same as the sequence number of the segment on
|
---|
1392 | ->ooseq. We check the lengths to see which one to
|
---|
1393 | discard. */
|
---|
1394 | if (inseg.len > next->len) {
|
---|
1395 | /* The incoming segment is larger than the old
|
---|
1396 | segment. We replace some segments with the new
|
---|
1397 | one. */
|
---|
1398 | cseg = tcp_seg_copy(&inseg);
|
---|
1399 | if (cseg != NULL) {
|
---|
1400 | if (prev != NULL) {
|
---|
1401 | prev->next = cseg;
|
---|
1402 | } else {
|
---|
1403 | pcb->ooseq = cseg;
|
---|
1404 | }
|
---|
1405 | tcp_oos_insert_segment(cseg, next);
|
---|
1406 | }
|
---|
1407 | break;
|
---|
1408 | } else {
|
---|
1409 | /* Either the lenghts are the same or the incoming
|
---|
1410 | segment was smaller than the old one; in either
|
---|
1411 | case, we ditch the incoming segment. */
|
---|
1412 | break;
|
---|
1413 | }
|
---|
1414 | } else {
|
---|
1415 | if (prev == NULL) {
|
---|
1416 | if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
|
---|
1417 | /* The sequence number of the incoming segment is lower
|
---|
1418 | than the sequence number of the first segment on the
|
---|
1419 | queue. We put the incoming segment first on the
|
---|
1420 | queue. */
|
---|
1421 | cseg = tcp_seg_copy(&inseg);
|
---|
1422 | if (cseg != NULL) {
|
---|
1423 | pcb->ooseq = cseg;
|
---|
1424 | tcp_oos_insert_segment(cseg, next);
|
---|
1425 | }
|
---|
1426 | break;
|
---|
1427 | }
|
---|
1428 | } else {
|
---|
1429 | /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
|
---|
1430 | TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
|
---|
1431 | if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
|
---|
1432 | /* The sequence number of the incoming segment is in
|
---|
1433 | between the sequence numbers of the previous and
|
---|
1434 | the next segment on ->ooseq. We trim trim the previous
|
---|
1435 | segment, delete next segments that included in received segment
|
---|
1436 | and trim received, if needed. */
|
---|
1437 | cseg = tcp_seg_copy(&inseg);
|
---|
1438 | if (cseg != NULL) {
|
---|
1439 | if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
|
---|
1440 | /* We need to trim the prev segment. */
|
---|
1441 | prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
|
---|
1442 | pbuf_realloc(prev->p, prev->len);
|
---|
1443 | }
|
---|
1444 | prev->next = cseg;
|
---|
1445 | tcp_oos_insert_segment(cseg, next);
|
---|
1446 | }
|
---|
1447 | break;
|
---|
1448 | }
|
---|
1449 | }
|
---|
1450 | /* If the "next" segment is the last segment on the
|
---|
1451 | ooseq queue, we add the incoming segment to the end
|
---|
1452 | of the list. */
|
---|
1453 | if (next->next == NULL &&
|
---|
1454 | TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
|
---|
1455 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
---|
1456 | /* segment "next" already contains all data */
|
---|
1457 | break;
|
---|
1458 | }
|
---|
1459 | next->next = tcp_seg_copy(&inseg);
|
---|
1460 | if (next->next != NULL) {
|
---|
1461 | if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
|
---|
1462 | /* We need to trim the last segment. */
|
---|
1463 | next->len = (u16_t)(seqno - next->tcphdr->seqno);
|
---|
1464 | pbuf_realloc(next->p, next->len);
|
---|
1465 | }
|
---|
1466 | /* check if the remote side overruns our receive window */
|
---|
1467 | if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
|
---|
1468 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
1469 | ("tcp_receive: other end overran receive window"
|
---|
1470 | "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
|
---|
1471 | seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1472 | if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
|
---|
1473 | /* Must remove the FIN from the header as we're trimming
|
---|
1474 | * that byte of sequence-space from the packet */
|
---|
1475 | TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
|
---|
1476 | }
|
---|
1477 | /* Adjust length of segment to fit in the window. */
|
---|
1478 | next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
|
---|
1479 | pbuf_realloc(next->next->p, next->next->len);
|
---|
1480 | tcplen = TCP_TCPLEN(next->next);
|
---|
1481 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
---|
1482 | (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1483 | }
|
---|
1484 | }
|
---|
1485 | break;
|
---|
1486 | }
|
---|
1487 | }
|
---|
1488 | prev = next;
|
---|
1489 | }
|
---|
1490 | }
|
---|
1491 | #if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
|
---|
1492 | /* Check that the data on ooseq doesn't exceed one of the limits
|
---|
1493 | and throw away everything above that limit. */
|
---|
1494 | ooseq_blen = 0;
|
---|
1495 | ooseq_qlen = 0;
|
---|
1496 | prev = NULL;
|
---|
1497 | for(next = pcb->ooseq; next != NULL; prev = next, next = next->next) {
|
---|
1498 | struct pbuf *p = next->p;
|
---|
1499 | ooseq_blen += p->tot_len;
|
---|
1500 | ooseq_qlen += pbuf_clen(p);
|
---|
1501 | if ((ooseq_blen > TCP_OOSEQ_MAX_BYTES) ||
|
---|
1502 | (ooseq_qlen > TCP_OOSEQ_MAX_PBUFS)) {
|
---|
1503 | /* too much ooseq data, dump this and everything after it */
|
---|
1504 | tcp_segs_free(next);
|
---|
1505 | if (prev == NULL) {
|
---|
1506 | /* first ooseq segment is too much, dump the whole queue */
|
---|
1507 | pcb->ooseq = NULL;
|
---|
1508 | } else {
|
---|
1509 | /* just dump 'next' and everything after it */
|
---|
1510 | prev->next = NULL;
|
---|
1511 | }
|
---|
1512 | break;
|
---|
1513 | }
|
---|
1514 | }
|
---|
1515 | #endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
|
---|
1516 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1517 | }
|
---|
1518 | } else {
|
---|
1519 | /* The incoming segment is not withing the window. */
|
---|
1520 | tcp_send_empty_ack(pcb);
|
---|
1521 | }
|
---|
1522 | } else {
|
---|
1523 | /* Segments with length 0 is taken care of here. Segments that
|
---|
1524 | fall out of the window are ACKed. */
|
---|
1525 | /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) ||
|
---|
1526 | TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
|
---|
1527 | if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
|
---|
1528 | tcp_ack_now(pcb);
|
---|
1529 | }
|
---|
1530 | }
|
---|
1531 | }
|
---|
1532 |
|
---|
1533 | /**
|
---|
1534 | * Parses the options contained in the incoming segment.
|
---|
1535 | *
|
---|
1536 | * Called from tcp_listen_input() and tcp_process().
|
---|
1537 | * Currently, only the MSS option is supported!
|
---|
1538 | *
|
---|
1539 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
1540 | */
|
---|
1541 | static void
|
---|
1542 | tcp_parseopt(struct tcp_pcb *pcb)
|
---|
1543 | {
|
---|
1544 | u16_t c, max_c;
|
---|
1545 | u16_t mss;
|
---|
1546 | u8_t *opts, opt;
|
---|
1547 | #if LWIP_TCP_TIMESTAMPS
|
---|
1548 | u32_t tsval;
|
---|
1549 | #endif
|
---|
1550 |
|
---|
1551 | opts = (u8_t *)tcphdr + TCP_HLEN;
|
---|
1552 |
|
---|
1553 | /* Parse the TCP MSS option, if present. */
|
---|
1554 | if(TCPH_HDRLEN(tcphdr) > 0x5) {
|
---|
1555 | max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
|
---|
1556 | for (c = 0; c < max_c; ) {
|
---|
1557 | opt = opts[c];
|
---|
1558 | switch (opt) {
|
---|
1559 | case 0x00:
|
---|
1560 | /* End of options. */
|
---|
1561 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
|
---|
1562 | return;
|
---|
1563 | case 0x01:
|
---|
1564 | /* NOP option. */
|
---|
1565 | ++c;
|
---|
1566 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
|
---|
1567 | break;
|
---|
1568 | case 0x02:
|
---|
1569 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
|
---|
1570 | if (opts[c + 1] != 0x04 || c + 0x04 > max_c) {
|
---|
1571 | /* Bad length */
|
---|
1572 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
1573 | return;
|
---|
1574 | }
|
---|
1575 | /* An MSS option with the right option length. */
|
---|
1576 | mss = (opts[c + 2] << 8) | opts[c + 3];
|
---|
1577 | /* Limit the mss to the configured TCP_MSS and prevent division by zero */
|
---|
1578 | pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
|
---|
1579 | /* Advance to next option */
|
---|
1580 | c += 0x04;
|
---|
1581 | break;
|
---|
1582 | #if LWIP_TCP_TIMESTAMPS
|
---|
1583 | case 0x08:
|
---|
1584 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
|
---|
1585 | if (opts[c + 1] != 0x0A || c + 0x0A > max_c) {
|
---|
1586 | /* Bad length */
|
---|
1587 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
1588 | return;
|
---|
1589 | }
|
---|
1590 | /* TCP timestamp option with valid length */
|
---|
1591 | tsval = (opts[c+2]) | (opts[c+3] << 8) |
|
---|
1592 | (opts[c+4] << 16) | (opts[c+5] << 24);
|
---|
1593 | if (flags & TCP_SYN) {
|
---|
1594 | pcb->ts_recent = ntohl(tsval);
|
---|
1595 | pcb->flags |= TF_TIMESTAMP;
|
---|
1596 | } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
|
---|
1597 | pcb->ts_recent = ntohl(tsval);
|
---|
1598 | }
|
---|
1599 | /* Advance to next option */
|
---|
1600 | c += 0x0A;
|
---|
1601 | break;
|
---|
1602 | #endif
|
---|
1603 | default:
|
---|
1604 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
|
---|
1605 | if (opts[c + 1] == 0) {
|
---|
1606 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
1607 | /* If the length field is zero, the options are malformed
|
---|
1608 | and we don't process them further. */
|
---|
1609 | return;
|
---|
1610 | }
|
---|
1611 | /* All other options have a length field, so that we easily
|
---|
1612 | can skip past them. */
|
---|
1613 | c += opts[c + 1];
|
---|
1614 | }
|
---|
1615 | }
|
---|
1616 | }
|
---|
1617 | }
|
---|
1618 |
|
---|
1619 | #endif /* LWIP_TCP */
|
---|