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/priv/tcp_priv.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/ip6.h"
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57 | #include "lwip/ip6_addr.h"
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58 | #if LWIP_ND6_TCP_REACHABILITY_HINTS
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59 | #include "lwip/nd6.h"
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60 | #endif /* LWIP_ND6_TCP_REACHABILITY_HINTS */
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61 |
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62 | #include <string.h>
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63 |
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64 | #ifdef LWIP_HOOK_FILENAME
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65 | #include LWIP_HOOK_FILENAME
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66 | #endif
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67 |
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68 | /** Initial CWND calculation as defined RFC 2581 */
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69 | #define LWIP_TCP_CALC_INITIAL_CWND(mss) ((tcpwnd_size_t)LWIP_MIN((4U * (mss)), LWIP_MAX((2U * (mss)), 4380U)))
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70 |
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71 | /* These variables are global to all functions involved in the input
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72 | processing of TCP segments. They are set by the tcp_input()
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73 | function. */
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74 | static struct tcp_seg inseg;
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75 | static struct tcp_hdr *tcphdr;
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76 | static u16_t tcphdr_optlen;
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77 | static u16_t tcphdr_opt1len;
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78 | static u8_t *tcphdr_opt2;
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79 | static u16_t tcp_optidx;
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80 | static u32_t seqno, ackno;
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81 | static tcpwnd_size_t recv_acked;
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82 | static u16_t tcplen;
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83 | static u8_t flags;
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84 |
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85 | static u8_t recv_flags;
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86 | static struct pbuf *recv_data;
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87 |
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88 | struct tcp_pcb *tcp_input_pcb;
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89 |
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90 | /* Forward declarations. */
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91 | static err_t tcp_process(struct tcp_pcb *pcb);
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92 | static void tcp_receive(struct tcp_pcb *pcb);
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93 | static void tcp_parseopt(struct tcp_pcb *pcb);
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94 |
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95 | static void tcp_listen_input(struct tcp_pcb_listen *pcb);
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96 | static void tcp_timewait_input(struct tcp_pcb *pcb);
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97 |
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98 | static int tcp_input_delayed_close(struct tcp_pcb *pcb);
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99 |
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100 | #if LWIP_TCP_SACK_OUT
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101 | static void tcp_add_sack(struct tcp_pcb *pcb, u32_t left, u32_t right);
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102 | static void tcp_remove_sacks_lt(struct tcp_pcb *pcb, u32_t seq);
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103 | #if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
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104 | static void tcp_remove_sacks_gt(struct tcp_pcb *pcb, u32_t seq);
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105 | #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
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106 | #endif /* LWIP_TCP_SACK_OUT */
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107 |
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108 | /**
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109 | * The initial input processing of TCP. It verifies the TCP header, demultiplexes
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110 | * the segment between the PCBs and passes it on to tcp_process(), which implements
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111 | * the TCP finite state machine. This function is called by the IP layer (in
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112 | * ip_input()).
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113 | *
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114 | * @param p received TCP segment to process (p->payload pointing to the TCP header)
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115 | * @param inp network interface on which this segment was received
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116 | */
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117 | void
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118 | tcp_input(struct pbuf *p, struct netif *inp)
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119 | {
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120 | struct tcp_pcb *pcb, *prev;
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121 | struct tcp_pcb_listen *lpcb;
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122 | #if SO_REUSE
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123 | struct tcp_pcb *lpcb_prev = NULL;
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124 | struct tcp_pcb_listen *lpcb_any = NULL;
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125 | #endif /* SO_REUSE */
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126 | u8_t hdrlen_bytes;
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127 | err_t err;
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128 |
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129 | LWIP_UNUSED_ARG(inp);
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130 | LWIP_ASSERT_CORE_LOCKED();
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131 | LWIP_ASSERT("tcp_input: invalid pbuf", p != NULL);
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132 |
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133 | PERF_START;
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134 |
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135 | TCP_STATS_INC(tcp.recv);
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136 | MIB2_STATS_INC(mib2.tcpinsegs);
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137 |
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138 | tcphdr = (struct tcp_hdr *)p->payload;
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139 |
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140 | #if TCP_INPUT_DEBUG
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141 | tcp_debug_print(tcphdr);
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142 | #endif
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143 |
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144 | /* Check that TCP header fits in payload */
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145 | if (p->len < TCP_HLEN) {
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146 | /* drop short packets */
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147 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
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148 | TCP_STATS_INC(tcp.lenerr);
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149 | goto dropped;
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150 | }
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151 |
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152 | /* Don't even process incoming broadcasts/multicasts. */
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153 | if (ip_addr_isbroadcast(ip_current_dest_addr(), ip_current_netif()) ||
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154 | ip_addr_ismulticast(ip_current_dest_addr())) {
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155 | TCP_STATS_INC(tcp.proterr);
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156 | goto dropped;
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157 | }
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158 |
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159 | #if CHECKSUM_CHECK_TCP
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160 | IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_TCP) {
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161 | /* Verify TCP checksum. */
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162 | u16_t chksum = ip_chksum_pseudo(p, IP_PROTO_TCP, p->tot_len,
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163 | ip_current_src_addr(), ip_current_dest_addr());
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164 | if (chksum != 0) {
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165 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
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166 | chksum));
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167 | tcp_debug_print(tcphdr);
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168 | TCP_STATS_INC(tcp.chkerr);
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169 | goto dropped;
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170 | }
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171 | }
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172 | #endif /* CHECKSUM_CHECK_TCP */
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173 |
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174 | /* sanity-check header length */
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175 | hdrlen_bytes = TCPH_HDRLEN_BYTES(tcphdr);
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176 | if ((hdrlen_bytes < TCP_HLEN) || (hdrlen_bytes > p->tot_len)) {
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177 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: invalid header length (%"U16_F")\n", (u16_t)hdrlen_bytes));
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178 | TCP_STATS_INC(tcp.lenerr);
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179 | goto dropped;
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180 | }
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181 |
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182 | /* Move the payload pointer in the pbuf so that it points to the
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183 | TCP data instead of the TCP header. */
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184 | tcphdr_optlen = (u16_t)(hdrlen_bytes - TCP_HLEN);
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185 | tcphdr_opt2 = NULL;
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186 | if (p->len >= hdrlen_bytes) {
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187 | /* all options are in the first pbuf */
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188 | tcphdr_opt1len = tcphdr_optlen;
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189 | pbuf_remove_header(p, hdrlen_bytes); /* cannot fail */
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190 | } else {
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191 | u16_t opt2len;
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192 | /* TCP header fits into first pbuf, options don't - data is in the next pbuf */
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193 | /* there must be a next pbuf, due to hdrlen_bytes sanity check above */
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194 | LWIP_ASSERT("p->next != NULL", p->next != NULL);
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195 |
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196 | /* advance over the TCP header (cannot fail) */
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197 | pbuf_remove_header(p, TCP_HLEN);
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198 |
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199 | /* determine how long the first and second parts of the options are */
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200 | tcphdr_opt1len = p->len;
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201 | opt2len = (u16_t)(tcphdr_optlen - tcphdr_opt1len);
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202 |
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203 | /* options continue in the next pbuf: set p to zero length and hide the
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204 | options in the next pbuf (adjusting p->tot_len) */
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205 | pbuf_remove_header(p, tcphdr_opt1len);
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206 |
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207 | /* check that the options fit in the second pbuf */
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208 | if (opt2len > p->next->len) {
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209 | /* drop short packets */
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210 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: options overflow second pbuf (%"U16_F" bytes)\n", p->next->len));
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211 | TCP_STATS_INC(tcp.lenerr);
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212 | goto dropped;
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213 | }
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214 |
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215 | /* remember the pointer to the second part of the options */
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216 | tcphdr_opt2 = (u8_t *)p->next->payload;
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217 |
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218 | /* advance p->next to point after the options, and manually
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219 | adjust p->tot_len to keep it consistent with the changed p->next */
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220 | pbuf_remove_header(p->next, opt2len);
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221 | p->tot_len = (u16_t)(p->tot_len - opt2len);
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222 |
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223 | LWIP_ASSERT("p->len == 0", p->len == 0);
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224 | LWIP_ASSERT("p->tot_len == p->next->tot_len", p->tot_len == p->next->tot_len);
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225 | }
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226 |
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227 | /* Convert fields in TCP header to host byte order. */
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228 | tcphdr->src = lwip_ntohs(tcphdr->src);
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229 | tcphdr->dest = lwip_ntohs(tcphdr->dest);
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230 | seqno = tcphdr->seqno = lwip_ntohl(tcphdr->seqno);
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231 | ackno = tcphdr->ackno = lwip_ntohl(tcphdr->ackno);
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232 | tcphdr->wnd = lwip_ntohs(tcphdr->wnd);
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233 |
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234 | flags = TCPH_FLAGS(tcphdr);
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235 | tcplen = p->tot_len;
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236 | if (flags & (TCP_FIN | TCP_SYN)) {
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237 | tcplen++;
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238 | if (tcplen < p->tot_len) {
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239 | /* u16_t overflow, cannot handle this */
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240 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: length u16_t overflow, cannot handle this\n"));
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241 | TCP_STATS_INC(tcp.lenerr);
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242 | goto dropped;
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243 | }
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244 | }
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245 |
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246 | /* Demultiplex an incoming segment. First, we check if it is destined
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247 | for an active connection. */
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248 | prev = NULL;
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249 |
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250 | for (pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
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251 | LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
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252 | LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
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253 | LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
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254 |
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255 | /* check if PCB is bound to specific netif */
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256 | if ((pcb->netif_idx != NETIF_NO_INDEX) &&
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257 | (pcb->netif_idx != netif_get_index(ip_data.current_input_netif))) {
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258 | prev = pcb;
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259 | continue;
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260 | }
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261 |
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262 | if (pcb->remote_port == tcphdr->src &&
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263 | pcb->local_port == tcphdr->dest &&
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264 | ip_addr_cmp(&pcb->remote_ip, ip_current_src_addr()) &&
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265 | ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) {
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266 | /* Move this PCB to the front of the list so that subsequent
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267 | lookups will be faster (we exploit locality in TCP segment
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268 | arrivals). */
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269 | LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
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270 | if (prev != NULL) {
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271 | prev->next = pcb->next;
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272 | pcb->next = tcp_active_pcbs;
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273 | tcp_active_pcbs = pcb;
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274 | } else {
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275 | TCP_STATS_INC(tcp.cachehit);
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276 | }
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277 | LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
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278 | break;
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279 | }
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280 | prev = pcb;
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281 | }
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282 |
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283 | if (pcb == NULL) {
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284 | /* If it did not go to an active connection, we check the connections
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285 | in the TIME-WAIT state. */
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286 | for (pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
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287 | LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
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288 |
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289 | /* check if PCB is bound to specific netif */
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290 | if ((pcb->netif_idx != NETIF_NO_INDEX) &&
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291 | (pcb->netif_idx != netif_get_index(ip_data.current_input_netif))) {
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292 | continue;
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293 | }
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294 |
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295 | if (pcb->remote_port == tcphdr->src &&
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296 | pcb->local_port == tcphdr->dest &&
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297 | ip_addr_cmp(&pcb->remote_ip, ip_current_src_addr()) &&
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298 | ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) {
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299 | /* We don't really care enough to move this PCB to the front
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300 | of the list since we are not very likely to receive that
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301 | many segments for connections in TIME-WAIT. */
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302 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
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303 | #ifdef LWIP_HOOK_TCP_INPACKET_PCB
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304 | if (LWIP_HOOK_TCP_INPACKET_PCB(pcb, tcphdr, tcphdr_optlen, tcphdr_opt1len,
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305 | tcphdr_opt2, p) == ERR_OK)
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306 | #endif
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307 | {
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308 | tcp_timewait_input(pcb);
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309 | }
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310 | pbuf_free(p);
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311 | return;
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312 | }
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313 | }
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314 |
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315 | /* Finally, if we still did not get a match, we check all PCBs that
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316 | are LISTENing for incoming connections. */
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317 | prev = NULL;
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318 | for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
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319 | /* check if PCB is bound to specific netif */
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320 | if ((lpcb->netif_idx != NETIF_NO_INDEX) &&
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321 | (lpcb->netif_idx != netif_get_index(ip_data.current_input_netif))) {
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322 | prev = (struct tcp_pcb *)lpcb;
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323 | continue;
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324 | }
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325 |
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326 | if (lpcb->local_port == tcphdr->dest) {
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327 | if (IP_IS_ANY_TYPE_VAL(lpcb->local_ip)) {
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328 | /* found an ANY TYPE (IPv4/IPv6) match */
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329 | #if SO_REUSE
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330 | lpcb_any = lpcb;
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331 | lpcb_prev = prev;
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332 | #else /* SO_REUSE */
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333 | break;
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334 | #endif /* SO_REUSE */
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335 | } else if (IP_ADDR_PCB_VERSION_MATCH_EXACT(lpcb, ip_current_dest_addr())) {
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336 | if (ip_addr_cmp(&lpcb->local_ip, ip_current_dest_addr())) {
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337 | /* found an exact match */
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338 | break;
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339 | } else if (ip_addr_isany(&lpcb->local_ip)) {
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340 | /* found an ANY-match */
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341 | #if SO_REUSE
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342 | lpcb_any = lpcb;
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343 | lpcb_prev = prev;
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344 | #else /* SO_REUSE */
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345 | break;
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346 | #endif /* SO_REUSE */
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347 | }
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348 | }
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349 | }
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350 | prev = (struct tcp_pcb *)lpcb;
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351 | }
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352 | #if SO_REUSE
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353 | /* first try specific local IP */
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354 | if (lpcb == NULL) {
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355 | /* only pass to ANY if no specific local IP has been found */
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356 | lpcb = lpcb_any;
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357 | prev = lpcb_prev;
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358 | }
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359 | #endif /* SO_REUSE */
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360 | if (lpcb != NULL) {
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361 | /* Move this PCB to the front of the list so that subsequent
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362 | lookups will be faster (we exploit locality in TCP segment
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363 | arrivals). */
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364 | if (prev != NULL) {
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365 | ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
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366 | /* our successor is the remainder of the listening list */
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367 | lpcb->next = tcp_listen_pcbs.listen_pcbs;
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368 | /* put this listening pcb at the head of the listening list */
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369 | tcp_listen_pcbs.listen_pcbs = lpcb;
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370 | } else {
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371 | TCP_STATS_INC(tcp.cachehit);
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372 | }
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373 |
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374 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
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375 | #ifdef LWIP_HOOK_TCP_INPACKET_PCB
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376 | if (LWIP_HOOK_TCP_INPACKET_PCB((struct tcp_pcb *)lpcb, tcphdr, tcphdr_optlen,
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377 | tcphdr_opt1len, tcphdr_opt2, p) == ERR_OK)
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378 | #endif
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379 | {
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380 | tcp_listen_input(lpcb);
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381 | }
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382 | pbuf_free(p);
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383 | return;
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384 | }
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385 | }
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386 |
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387 | #if TCP_INPUT_DEBUG
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388 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
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389 | tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
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390 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
|
---|
391 | #endif /* TCP_INPUT_DEBUG */
|
---|
392 |
|
---|
393 |
|
---|
394 | #ifdef LWIP_HOOK_TCP_INPACKET_PCB
|
---|
395 | if ((pcb != NULL) && LWIP_HOOK_TCP_INPACKET_PCB(pcb, tcphdr, tcphdr_optlen,
|
---|
396 | tcphdr_opt1len, tcphdr_opt2, p) != ERR_OK) {
|
---|
397 | pbuf_free(p);
|
---|
398 | return;
|
---|
399 | }
|
---|
400 | #endif
|
---|
401 | if (pcb != NULL) {
|
---|
402 | /* The incoming segment belongs to a connection. */
|
---|
403 | #if TCP_INPUT_DEBUG
|
---|
404 | tcp_debug_print_state(pcb->state);
|
---|
405 | #endif /* TCP_INPUT_DEBUG */
|
---|
406 |
|
---|
407 | /* Set up a tcp_seg structure. */
|
---|
408 | inseg.next = NULL;
|
---|
409 | inseg.len = p->tot_len;
|
---|
410 | inseg.p = p;
|
---|
411 | inseg.tcphdr = tcphdr;
|
---|
412 |
|
---|
413 | recv_data = NULL;
|
---|
414 | recv_flags = 0;
|
---|
415 | recv_acked = 0;
|
---|
416 |
|
---|
417 | if (flags & TCP_PSH) {
|
---|
418 | p->flags |= PBUF_FLAG_PUSH;
|
---|
419 | }
|
---|
420 |
|
---|
421 | /* If there is data which was previously "refused" by upper layer */
|
---|
422 | if (pcb->refused_data != NULL) {
|
---|
423 | if ((tcp_process_refused_data(pcb) == ERR_ABRT) ||
|
---|
424 | ((pcb->refused_data != NULL) && (tcplen > 0))) {
|
---|
425 | /* pcb has been aborted or refused data is still refused and the new
|
---|
426 | segment contains data */
|
---|
427 | if (pcb->rcv_ann_wnd == 0) {
|
---|
428 | /* this is a zero-window probe, we respond to it with current RCV.NXT
|
---|
429 | and drop the data segment */
|
---|
430 | tcp_send_empty_ack(pcb);
|
---|
431 | }
|
---|
432 | TCP_STATS_INC(tcp.drop);
|
---|
433 | MIB2_STATS_INC(mib2.tcpinerrs);
|
---|
434 | goto aborted;
|
---|
435 | }
|
---|
436 | }
|
---|
437 | tcp_input_pcb = pcb;
|
---|
438 | err = tcp_process(pcb);
|
---|
439 | /* A return value of ERR_ABRT means that tcp_abort() was called
|
---|
440 | and that the pcb has been freed. If so, we don't do anything. */
|
---|
441 | if (err != ERR_ABRT) {
|
---|
442 | if (recv_flags & TF_RESET) {
|
---|
443 | /* TF_RESET means that the connection was reset by the other
|
---|
444 | end. We then call the error callback to inform the
|
---|
445 | application that the connection is dead before we
|
---|
446 | deallocate the PCB. */
|
---|
447 | TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_RST);
|
---|
448 | tcp_pcb_remove(&tcp_active_pcbs, pcb);
|
---|
449 | tcp_free(pcb);
|
---|
450 | } else {
|
---|
451 | err = ERR_OK;
|
---|
452 | /* If the application has registered a "sent" function to be
|
---|
453 | called when new send buffer space is available, we call it
|
---|
454 | now. */
|
---|
455 | if (recv_acked > 0) {
|
---|
456 | u16_t acked16;
|
---|
457 | #if LWIP_WND_SCALE
|
---|
458 | /* recv_acked is u32_t but the sent callback only takes a u16_t,
|
---|
459 | so we might have to call it multiple times. */
|
---|
460 | u32_t acked = recv_acked;
|
---|
461 | while (acked > 0) {
|
---|
462 | acked16 = (u16_t)LWIP_MIN(acked, 0xffffu);
|
---|
463 | acked -= acked16;
|
---|
464 | #else
|
---|
465 | {
|
---|
466 | acked16 = recv_acked;
|
---|
467 | #endif
|
---|
468 | TCP_EVENT_SENT(pcb, (u16_t)acked16, err);
|
---|
469 | if (err == ERR_ABRT) {
|
---|
470 | goto aborted;
|
---|
471 | }
|
---|
472 | }
|
---|
473 | recv_acked = 0;
|
---|
474 | }
|
---|
475 | if (tcp_input_delayed_close(pcb)) {
|
---|
476 | goto aborted;
|
---|
477 | }
|
---|
478 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
479 | while (recv_data != NULL) {
|
---|
480 | struct pbuf *rest = NULL;
|
---|
481 | pbuf_split_64k(recv_data, &rest);
|
---|
482 | #else /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
483 | if (recv_data != NULL) {
|
---|
484 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
485 |
|
---|
486 | LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
|
---|
487 | if (pcb->flags & TF_RXCLOSED) {
|
---|
488 | /* received data although already closed -> abort (send RST) to
|
---|
489 | notify the remote host that not all data has been processed */
|
---|
490 | pbuf_free(recv_data);
|
---|
491 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
492 | if (rest != NULL) {
|
---|
493 | pbuf_free(rest);
|
---|
494 | }
|
---|
495 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
496 | tcp_abort(pcb);
|
---|
497 | goto aborted;
|
---|
498 | }
|
---|
499 |
|
---|
500 | /* Notify application that data has been received. */
|
---|
501 | TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
|
---|
502 | if (err == ERR_ABRT) {
|
---|
503 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
504 | if (rest != NULL) {
|
---|
505 | pbuf_free(rest);
|
---|
506 | }
|
---|
507 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
508 | goto aborted;
|
---|
509 | }
|
---|
510 |
|
---|
511 | /* If the upper layer can't receive this data, store it */
|
---|
512 | if (err != ERR_OK) {
|
---|
513 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
514 | if (rest != NULL) {
|
---|
515 | pbuf_cat(recv_data, rest);
|
---|
516 | }
|
---|
517 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
518 | pcb->refused_data = recv_data;
|
---|
519 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
|
---|
520 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
521 | break;
|
---|
522 | } else {
|
---|
523 | /* Upper layer received the data, go on with the rest if > 64K */
|
---|
524 | recv_data = rest;
|
---|
525 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
526 | }
|
---|
527 | }
|
---|
528 |
|
---|
529 | /* If a FIN segment was received, we call the callback
|
---|
530 | function with a NULL buffer to indicate EOF. */
|
---|
531 | if (recv_flags & TF_GOT_FIN) {
|
---|
532 | if (pcb->refused_data != NULL) {
|
---|
533 | /* Delay this if we have refused data. */
|
---|
534 | pcb->refused_data->flags |= PBUF_FLAG_TCP_FIN;
|
---|
535 | } else {
|
---|
536 | /* correct rcv_wnd as the application won't call tcp_recved()
|
---|
537 | for the FIN's seqno */
|
---|
538 | if (pcb->rcv_wnd != TCP_WND_MAX(pcb)) {
|
---|
539 | pcb->rcv_wnd++;
|
---|
540 | }
|
---|
541 | TCP_EVENT_CLOSED(pcb, err);
|
---|
542 | if (err == ERR_ABRT) {
|
---|
543 | goto aborted;
|
---|
544 | }
|
---|
545 | }
|
---|
546 | }
|
---|
547 |
|
---|
548 | tcp_input_pcb = NULL;
|
---|
549 | if (tcp_input_delayed_close(pcb)) {
|
---|
550 | goto aborted;
|
---|
551 | }
|
---|
552 | /* Try to send something out. */
|
---|
553 | tcp_output(pcb);
|
---|
554 | #if TCP_INPUT_DEBUG
|
---|
555 | #if TCP_DEBUG
|
---|
556 | tcp_debug_print_state(pcb->state);
|
---|
557 | #endif /* TCP_DEBUG */
|
---|
558 | #endif /* TCP_INPUT_DEBUG */
|
---|
559 | }
|
---|
560 | }
|
---|
561 | /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
|
---|
562 | Below this line, 'pcb' may not be dereferenced! */
|
---|
563 | aborted:
|
---|
564 | tcp_input_pcb = NULL;
|
---|
565 | recv_data = NULL;
|
---|
566 |
|
---|
567 | /* give up our reference to inseg.p */
|
---|
568 | if (inseg.p != NULL) {
|
---|
569 | pbuf_free(inseg.p);
|
---|
570 | inseg.p = NULL;
|
---|
571 | }
|
---|
572 | } else {
|
---|
573 | /* If no matching PCB was found, send a TCP RST (reset) to the
|
---|
574 | sender. */
|
---|
575 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
|
---|
576 | if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
|
---|
577 | TCP_STATS_INC(tcp.proterr);
|
---|
578 | TCP_STATS_INC(tcp.drop);
|
---|
579 | tcp_rst(NULL, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
580 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
581 | }
|
---|
582 | pbuf_free(p);
|
---|
583 | }
|
---|
584 |
|
---|
585 | LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
|
---|
586 | PERF_STOP("tcp_input");
|
---|
587 | return;
|
---|
588 | dropped:
|
---|
589 | TCP_STATS_INC(tcp.drop);
|
---|
590 | MIB2_STATS_INC(mib2.tcpinerrs);
|
---|
591 | pbuf_free(p);
|
---|
592 | }
|
---|
593 |
|
---|
594 | /** Called from tcp_input to check for TF_CLOSED flag. This results in closing
|
---|
595 | * and deallocating a pcb at the correct place to ensure noone references it
|
---|
596 | * any more.
|
---|
597 | * @returns 1 if the pcb has been closed and deallocated, 0 otherwise
|
---|
598 | */
|
---|
599 | static int
|
---|
600 | tcp_input_delayed_close(struct tcp_pcb *pcb)
|
---|
601 | {
|
---|
602 | LWIP_ASSERT("tcp_input_delayed_close: invalid pcb", pcb != NULL);
|
---|
603 |
|
---|
604 | if (recv_flags & TF_CLOSED) {
|
---|
605 | /* The connection has been closed and we will deallocate the
|
---|
606 | PCB. */
|
---|
607 | if (!(pcb->flags & TF_RXCLOSED)) {
|
---|
608 | /* Connection closed although the application has only shut down the
|
---|
609 | tx side: call the PCB's err callback and indicate the closure to
|
---|
610 | ensure the application doesn't continue using the PCB. */
|
---|
611 | TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_CLSD);
|
---|
612 | }
|
---|
613 | tcp_pcb_remove(&tcp_active_pcbs, pcb);
|
---|
614 | tcp_free(pcb);
|
---|
615 | return 1;
|
---|
616 | }
|
---|
617 | return 0;
|
---|
618 | }
|
---|
619 |
|
---|
620 | /**
|
---|
621 | * Called by tcp_input() when a segment arrives for a listening
|
---|
622 | * connection (from tcp_input()).
|
---|
623 | *
|
---|
624 | * @param pcb the tcp_pcb_listen for which a segment arrived
|
---|
625 | *
|
---|
626 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
627 | * involved is passed as a parameter to this function
|
---|
628 | */
|
---|
629 | static void
|
---|
630 | tcp_listen_input(struct tcp_pcb_listen *pcb)
|
---|
631 | {
|
---|
632 | struct tcp_pcb *npcb;
|
---|
633 | u32_t iss;
|
---|
634 | err_t rc;
|
---|
635 |
|
---|
636 | if (flags & TCP_RST) {
|
---|
637 | /* An incoming RST should be ignored. Return. */
|
---|
638 | return;
|
---|
639 | }
|
---|
640 |
|
---|
641 | LWIP_ASSERT("tcp_listen_input: invalid pcb", pcb != NULL);
|
---|
642 |
|
---|
643 | /* In the LISTEN state, we check for incoming SYN segments,
|
---|
644 | creates a new PCB, and responds with a SYN|ACK. */
|
---|
645 | if (flags & TCP_ACK) {
|
---|
646 | /* For incoming segments with the ACK flag set, respond with a
|
---|
647 | RST. */
|
---|
648 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
|
---|
649 | tcp_rst((const struct tcp_pcb *)pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
650 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
651 | } else if (flags & TCP_SYN) {
|
---|
652 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
|
---|
653 | #if TCP_LISTEN_BACKLOG
|
---|
654 | if (pcb->accepts_pending >= pcb->backlog) {
|
---|
655 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
|
---|
656 | return;
|
---|
657 | }
|
---|
658 | #endif /* TCP_LISTEN_BACKLOG */
|
---|
659 | npcb = tcp_alloc(pcb->prio);
|
---|
660 | /* If a new PCB could not be created (probably due to lack of memory),
|
---|
661 | we don't do anything, but rely on the sender will retransmit the
|
---|
662 | SYN at a time when we have more memory available. */
|
---|
663 | if (npcb == NULL) {
|
---|
664 | err_t err;
|
---|
665 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
|
---|
666 | TCP_STATS_INC(tcp.memerr);
|
---|
667 | TCP_EVENT_ACCEPT(pcb, NULL, pcb->callback_arg, ERR_MEM, err);
|
---|
668 | LWIP_UNUSED_ARG(err); /* err not useful here */
|
---|
669 | return;
|
---|
670 | }
|
---|
671 | #if TCP_LISTEN_BACKLOG
|
---|
672 | pcb->accepts_pending++;
|
---|
673 | tcp_set_flags(npcb, TF_BACKLOGPEND);
|
---|
674 | #endif /* TCP_LISTEN_BACKLOG */
|
---|
675 | /* Set up the new PCB. */
|
---|
676 | ip_addr_copy(npcb->local_ip, *ip_current_dest_addr());
|
---|
677 | ip_addr_copy(npcb->remote_ip, *ip_current_src_addr());
|
---|
678 | npcb->local_port = pcb->local_port;
|
---|
679 | npcb->remote_port = tcphdr->src;
|
---|
680 | npcb->state = SYN_RCVD;
|
---|
681 | npcb->rcv_nxt = seqno + 1;
|
---|
682 | npcb->rcv_ann_right_edge = npcb->rcv_nxt;
|
---|
683 | iss = tcp_next_iss(npcb);
|
---|
684 | npcb->snd_wl2 = iss;
|
---|
685 | npcb->snd_nxt = iss;
|
---|
686 | npcb->lastack = iss;
|
---|
687 | npcb->snd_lbb = iss;
|
---|
688 | npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
|
---|
689 | npcb->callback_arg = pcb->callback_arg;
|
---|
690 | #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
|
---|
691 | npcb->listener = pcb;
|
---|
692 | #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
|
---|
693 | /* inherit socket options */
|
---|
694 | npcb->so_options = pcb->so_options & SOF_INHERITED;
|
---|
695 | npcb->netif_idx = pcb->netif_idx;
|
---|
696 | /* Register the new PCB so that we can begin receiving segments
|
---|
697 | for it. */
|
---|
698 | TCP_REG_ACTIVE(npcb);
|
---|
699 |
|
---|
700 | /* Parse any options in the SYN. */
|
---|
701 | tcp_parseopt(npcb);
|
---|
702 | npcb->snd_wnd = tcphdr->wnd;
|
---|
703 | npcb->snd_wnd_max = npcb->snd_wnd;
|
---|
704 |
|
---|
705 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
706 | npcb->mss = tcp_eff_send_mss(npcb->mss, &npcb->local_ip, &npcb->remote_ip);
|
---|
707 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
708 |
|
---|
709 | MIB2_STATS_INC(mib2.tcppassiveopens);
|
---|
710 |
|
---|
711 | #if LWIP_TCP_PCB_NUM_EXT_ARGS
|
---|
712 | if (tcp_ext_arg_invoke_callbacks_passive_open(pcb, npcb) != ERR_OK) {
|
---|
713 | tcp_abandon(npcb, 0);
|
---|
714 | return;
|
---|
715 | }
|
---|
716 | #endif
|
---|
717 |
|
---|
718 | /* Send a SYN|ACK together with the MSS option. */
|
---|
719 | rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
|
---|
720 | if (rc != ERR_OK) {
|
---|
721 | tcp_abandon(npcb, 0);
|
---|
722 | return;
|
---|
723 | }
|
---|
724 | tcp_output(npcb);
|
---|
725 | }
|
---|
726 | return;
|
---|
727 | }
|
---|
728 |
|
---|
729 | /**
|
---|
730 | * Called by tcp_input() when a segment arrives for a connection in
|
---|
731 | * TIME_WAIT.
|
---|
732 | *
|
---|
733 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
734 | *
|
---|
735 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
736 | * involved is passed as a parameter to this function
|
---|
737 | */
|
---|
738 | static void
|
---|
739 | tcp_timewait_input(struct tcp_pcb *pcb)
|
---|
740 | {
|
---|
741 | /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
|
---|
742 | /* RFC 793 3.9 Event Processing - Segment Arrives:
|
---|
743 | * - first check sequence number - we skip that one in TIME_WAIT (always
|
---|
744 | * acceptable since we only send ACKs)
|
---|
745 | * - second check the RST bit (... return) */
|
---|
746 | if (flags & TCP_RST) {
|
---|
747 | return;
|
---|
748 | }
|
---|
749 |
|
---|
750 | LWIP_ASSERT("tcp_timewait_input: invalid pcb", pcb != NULL);
|
---|
751 |
|
---|
752 | /* - fourth, check the SYN bit, */
|
---|
753 | if (flags & TCP_SYN) {
|
---|
754 | /* If an incoming segment is not acceptable, an acknowledgment
|
---|
755 | should be sent in reply */
|
---|
756 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd)) {
|
---|
757 | /* If the SYN is in the window it is an error, send a reset */
|
---|
758 | tcp_rst(pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
759 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
760 | return;
|
---|
761 | }
|
---|
762 | } else if (flags & TCP_FIN) {
|
---|
763 | /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
|
---|
764 | Restart the 2 MSL time-wait timeout.*/
|
---|
765 | pcb->tmr = tcp_ticks;
|
---|
766 | }
|
---|
767 |
|
---|
768 | if ((tcplen > 0)) {
|
---|
769 | /* Acknowledge data, FIN or out-of-window SYN */
|
---|
770 | tcp_ack_now(pcb);
|
---|
771 | tcp_output(pcb);
|
---|
772 | }
|
---|
773 | return;
|
---|
774 | }
|
---|
775 |
|
---|
776 | /**
|
---|
777 | * Implements the TCP state machine. Called by tcp_input. In some
|
---|
778 | * states tcp_receive() is called to receive data. The tcp_seg
|
---|
779 | * argument will be freed by the caller (tcp_input()) unless the
|
---|
780 | * recv_data pointer in the pcb is set.
|
---|
781 | *
|
---|
782 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
783 | *
|
---|
784 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
785 | * involved is passed as a parameter to this function
|
---|
786 | */
|
---|
787 | static err_t
|
---|
788 | tcp_process(struct tcp_pcb *pcb)
|
---|
789 | {
|
---|
790 | struct tcp_seg *rseg;
|
---|
791 | u8_t acceptable = 0;
|
---|
792 | err_t err;
|
---|
793 |
|
---|
794 | err = ERR_OK;
|
---|
795 |
|
---|
796 | LWIP_ASSERT("tcp_process: invalid pcb", pcb != NULL);
|
---|
797 |
|
---|
798 | /* Process incoming RST segments. */
|
---|
799 | if (flags & TCP_RST) {
|
---|
800 | /* First, determine if the reset is acceptable. */
|
---|
801 | if (pcb->state == SYN_SENT) {
|
---|
802 | /* "In the SYN-SENT state (a RST received in response to an initial SYN),
|
---|
803 | the RST is acceptable if the ACK field acknowledges the SYN." */
|
---|
804 | if (ackno == pcb->snd_nxt) {
|
---|
805 | acceptable = 1;
|
---|
806 | }
|
---|
807 | } else {
|
---|
808 | /* "In all states except SYN-SENT, all reset (RST) segments are validated
|
---|
809 | by checking their SEQ-fields." */
|
---|
810 | if (seqno == pcb->rcv_nxt) {
|
---|
811 | acceptable = 1;
|
---|
812 | } else if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
---|
813 | pcb->rcv_nxt + pcb->rcv_wnd)) {
|
---|
814 | /* If the sequence number is inside the window, we send a challenge ACK
|
---|
815 | and wait for a re-send with matching sequence number.
|
---|
816 | This follows RFC 5961 section 3.2 and addresses CVE-2004-0230
|
---|
817 | (RST spoofing attack), which is present in RFC 793 RST handling. */
|
---|
818 | tcp_ack_now(pcb);
|
---|
819 | }
|
---|
820 | }
|
---|
821 |
|
---|
822 | if (acceptable) {
|
---|
823 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
|
---|
824 | LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
|
---|
825 | recv_flags |= TF_RESET;
|
---|
826 | tcp_clear_flags(pcb, TF_ACK_DELAY);
|
---|
827 | return ERR_RST;
|
---|
828 | } else {
|
---|
829 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
---|
830 | seqno, pcb->rcv_nxt));
|
---|
831 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
---|
832 | seqno, pcb->rcv_nxt));
|
---|
833 | return ERR_OK;
|
---|
834 | }
|
---|
835 | }
|
---|
836 |
|
---|
837 | if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
|
---|
838 | /* Cope with new connection attempt after remote end crashed */
|
---|
839 | tcp_ack_now(pcb);
|
---|
840 | return ERR_OK;
|
---|
841 | }
|
---|
842 |
|
---|
843 | if ((pcb->flags & TF_RXCLOSED) == 0) {
|
---|
844 | /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
|
---|
845 | pcb->tmr = tcp_ticks;
|
---|
846 | }
|
---|
847 | pcb->keep_cnt_sent = 0;
|
---|
848 | pcb->persist_probe = 0;
|
---|
849 |
|
---|
850 | tcp_parseopt(pcb);
|
---|
851 |
|
---|
852 | /* Do different things depending on the TCP state. */
|
---|
853 | switch (pcb->state) {
|
---|
854 | case SYN_SENT:
|
---|
855 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
|
---|
856 | pcb->snd_nxt, lwip_ntohl(pcb->unacked->tcphdr->seqno)));
|
---|
857 | /* received SYN ACK with expected sequence number? */
|
---|
858 | if ((flags & TCP_ACK) && (flags & TCP_SYN)
|
---|
859 | && (ackno == pcb->lastack + 1)) {
|
---|
860 | pcb->rcv_nxt = seqno + 1;
|
---|
861 | pcb->rcv_ann_right_edge = pcb->rcv_nxt;
|
---|
862 | pcb->lastack = ackno;
|
---|
863 | pcb->snd_wnd = tcphdr->wnd;
|
---|
864 | pcb->snd_wnd_max = pcb->snd_wnd;
|
---|
865 | pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
|
---|
866 | pcb->state = ESTABLISHED;
|
---|
867 |
|
---|
868 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
869 | pcb->mss = tcp_eff_send_mss(pcb->mss, &pcb->local_ip, &pcb->remote_ip);
|
---|
870 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
871 |
|
---|
872 | pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss);
|
---|
873 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_process (SENT): cwnd %"TCPWNDSIZE_F
|
---|
874 | " ssthresh %"TCPWNDSIZE_F"\n",
|
---|
875 | pcb->cwnd, pcb->ssthresh));
|
---|
876 | LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
|
---|
877 | --pcb->snd_queuelen;
|
---|
878 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"TCPWNDSIZE_F"\n", (tcpwnd_size_t)pcb->snd_queuelen));
|
---|
879 | rseg = pcb->unacked;
|
---|
880 | if (rseg == NULL) {
|
---|
881 | /* might happen if tcp_output fails in tcp_rexmit_rto()
|
---|
882 | in which case the segment is on the unsent list */
|
---|
883 | rseg = pcb->unsent;
|
---|
884 | LWIP_ASSERT("no segment to free", rseg != NULL);
|
---|
885 | pcb->unsent = rseg->next;
|
---|
886 | } else {
|
---|
887 | pcb->unacked = rseg->next;
|
---|
888 | }
|
---|
889 | tcp_seg_free(rseg);
|
---|
890 |
|
---|
891 | /* If there's nothing left to acknowledge, stop the retransmit
|
---|
892 | timer, otherwise reset it to start again */
|
---|
893 | if (pcb->unacked == NULL) {
|
---|
894 | pcb->rtime = -1;
|
---|
895 | } else {
|
---|
896 | pcb->rtime = 0;
|
---|
897 | pcb->nrtx = 0;
|
---|
898 | }
|
---|
899 |
|
---|
900 | /* Call the user specified function to call when successfully
|
---|
901 | * connected. */
|
---|
902 | TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
|
---|
903 | if (err == ERR_ABRT) {
|
---|
904 | return ERR_ABRT;
|
---|
905 | }
|
---|
906 | tcp_ack_now(pcb);
|
---|
907 | }
|
---|
908 | /* received ACK? possibly a half-open connection */
|
---|
909 | else if (flags & TCP_ACK) {
|
---|
910 | /* send a RST to bring the other side in a non-synchronized state. */
|
---|
911 | tcp_rst(pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
912 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
913 | /* Resend SYN immediately (don't wait for rto timeout) to establish
|
---|
914 | connection faster, but do not send more SYNs than we otherwise would
|
---|
915 | have, or we might get caught in a loop on loopback interfaces. */
|
---|
916 | if (pcb->nrtx < TCP_SYNMAXRTX) {
|
---|
917 | pcb->rtime = 0;
|
---|
918 | tcp_rexmit_rto(pcb);
|
---|
919 | }
|
---|
920 | }
|
---|
921 | break;
|
---|
922 | case SYN_RCVD:
|
---|
923 | if (flags & TCP_ACK) {
|
---|
924 | /* expected ACK number? */
|
---|
925 | if (TCP_SEQ_BETWEEN(ackno, pcb->lastack + 1, pcb->snd_nxt)) {
|
---|
926 | pcb->state = ESTABLISHED;
|
---|
927 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
928 | #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
|
---|
929 | if (pcb->listener == NULL) {
|
---|
930 | /* listen pcb might be closed by now */
|
---|
931 | err = ERR_VAL;
|
---|
932 | } else
|
---|
933 | #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
|
---|
934 | {
|
---|
935 | #if LWIP_CALLBACK_API
|
---|
936 | LWIP_ASSERT("pcb->listener->accept != NULL", pcb->listener->accept != NULL);
|
---|
937 | #endif
|
---|
938 | tcp_backlog_accepted(pcb);
|
---|
939 | /* Call the accept function. */
|
---|
940 | TCP_EVENT_ACCEPT(pcb->listener, pcb, pcb->callback_arg, ERR_OK, err);
|
---|
941 | }
|
---|
942 | if (err != ERR_OK) {
|
---|
943 | /* If the accept function returns with an error, we abort
|
---|
944 | * the connection. */
|
---|
945 | /* Already aborted? */
|
---|
946 | if (err != ERR_ABRT) {
|
---|
947 | tcp_abort(pcb);
|
---|
948 | }
|
---|
949 | return ERR_ABRT;
|
---|
950 | }
|
---|
951 | /* If there was any data contained within this ACK,
|
---|
952 | * we'd better pass it on to the application as well. */
|
---|
953 | tcp_receive(pcb);
|
---|
954 |
|
---|
955 | /* Prevent ACK for SYN to generate a sent event */
|
---|
956 | if (recv_acked != 0) {
|
---|
957 | recv_acked--;
|
---|
958 | }
|
---|
959 |
|
---|
960 | pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss);
|
---|
961 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_process (SYN_RCVD): cwnd %"TCPWNDSIZE_F
|
---|
962 | " ssthresh %"TCPWNDSIZE_F"\n",
|
---|
963 | pcb->cwnd, pcb->ssthresh));
|
---|
964 |
|
---|
965 | if (recv_flags & TF_GOT_FIN) {
|
---|
966 | tcp_ack_now(pcb);
|
---|
967 | pcb->state = CLOSE_WAIT;
|
---|
968 | }
|
---|
969 | } else {
|
---|
970 | /* incorrect ACK number, send RST */
|
---|
971 | tcp_rst(pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
972 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
973 | }
|
---|
974 | } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
|
---|
975 | /* Looks like another copy of the SYN - retransmit our SYN-ACK */
|
---|
976 | tcp_rexmit(pcb);
|
---|
977 | }
|
---|
978 | break;
|
---|
979 | case CLOSE_WAIT:
|
---|
980 | /* FALLTHROUGH */
|
---|
981 | case ESTABLISHED:
|
---|
982 | tcp_receive(pcb);
|
---|
983 | if (recv_flags & TF_GOT_FIN) { /* passive close */
|
---|
984 | tcp_ack_now(pcb);
|
---|
985 | pcb->state = CLOSE_WAIT;
|
---|
986 | }
|
---|
987 | break;
|
---|
988 | case FIN_WAIT_1:
|
---|
989 | tcp_receive(pcb);
|
---|
990 | if (recv_flags & TF_GOT_FIN) {
|
---|
991 | if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt) &&
|
---|
992 | pcb->unsent == NULL) {
|
---|
993 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
994 | ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
995 | tcp_ack_now(pcb);
|
---|
996 | tcp_pcb_purge(pcb);
|
---|
997 | TCP_RMV_ACTIVE(pcb);
|
---|
998 | pcb->state = TIME_WAIT;
|
---|
999 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
1000 | } else {
|
---|
1001 | tcp_ack_now(pcb);
|
---|
1002 | pcb->state = CLOSING;
|
---|
1003 | }
|
---|
1004 | } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt) &&
|
---|
1005 | pcb->unsent == NULL) {
|
---|
1006 | pcb->state = FIN_WAIT_2;
|
---|
1007 | }
|
---|
1008 | break;
|
---|
1009 | case FIN_WAIT_2:
|
---|
1010 | tcp_receive(pcb);
|
---|
1011 | if (recv_flags & TF_GOT_FIN) {
|
---|
1012 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
1013 | tcp_ack_now(pcb);
|
---|
1014 | tcp_pcb_purge(pcb);
|
---|
1015 | TCP_RMV_ACTIVE(pcb);
|
---|
1016 | pcb->state = TIME_WAIT;
|
---|
1017 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
1018 | }
|
---|
1019 | break;
|
---|
1020 | case CLOSING:
|
---|
1021 | tcp_receive(pcb);
|
---|
1022 | if ((flags & TCP_ACK) && ackno == pcb->snd_nxt && pcb->unsent == NULL) {
|
---|
1023 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
1024 | tcp_pcb_purge(pcb);
|
---|
1025 | TCP_RMV_ACTIVE(pcb);
|
---|
1026 | pcb->state = TIME_WAIT;
|
---|
1027 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
1028 | }
|
---|
1029 | break;
|
---|
1030 | case LAST_ACK:
|
---|
1031 | tcp_receive(pcb);
|
---|
1032 | if ((flags & TCP_ACK) && ackno == pcb->snd_nxt && pcb->unsent == NULL) {
|
---|
1033 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
1034 | /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
|
---|
1035 | recv_flags |= TF_CLOSED;
|
---|
1036 | }
|
---|
1037 | break;
|
---|
1038 | default:
|
---|
1039 | break;
|
---|
1040 | }
|
---|
1041 | return ERR_OK;
|
---|
1042 | }
|
---|
1043 |
|
---|
1044 | #if TCP_QUEUE_OOSEQ
|
---|
1045 | /**
|
---|
1046 | * Insert segment into the list (segments covered with new one will be deleted)
|
---|
1047 | *
|
---|
1048 | * Called from tcp_receive()
|
---|
1049 | */
|
---|
1050 | static void
|
---|
1051 | tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
|
---|
1052 | {
|
---|
1053 | struct tcp_seg *old_seg;
|
---|
1054 |
|
---|
1055 | LWIP_ASSERT("tcp_oos_insert_segment: invalid cseg", cseg != NULL);
|
---|
1056 |
|
---|
1057 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
---|
1058 | /* received segment overlaps all following segments */
|
---|
1059 | tcp_segs_free(next);
|
---|
1060 | next = NULL;
|
---|
1061 | } else {
|
---|
1062 | /* delete some following segments
|
---|
1063 | oos queue may have segments with FIN flag */
|
---|
1064 | while (next &&
|
---|
1065 | TCP_SEQ_GEQ((seqno + cseg->len),
|
---|
1066 | (next->tcphdr->seqno + next->len))) {
|
---|
1067 | /* cseg with FIN already processed */
|
---|
1068 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
---|
1069 | TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
|
---|
1070 | }
|
---|
1071 | old_seg = next;
|
---|
1072 | next = next->next;
|
---|
1073 | tcp_seg_free(old_seg);
|
---|
1074 | }
|
---|
1075 | if (next &&
|
---|
1076 | TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
|
---|
1077 | /* We need to trim the incoming segment. */
|
---|
1078 | cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
|
---|
1079 | pbuf_realloc(cseg->p, cseg->len);
|
---|
1080 | }
|
---|
1081 | }
|
---|
1082 | cseg->next = next;
|
---|
1083 | }
|
---|
1084 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1085 |
|
---|
1086 | /** Remove segments from a list if the incoming ACK acknowledges them */
|
---|
1087 | static struct tcp_seg *
|
---|
1088 | tcp_free_acked_segments(struct tcp_pcb *pcb, struct tcp_seg *seg_list, const char *dbg_list_name,
|
---|
1089 | struct tcp_seg *dbg_other_seg_list)
|
---|
1090 | {
|
---|
1091 | struct tcp_seg *next;
|
---|
1092 | u16_t clen;
|
---|
1093 |
|
---|
1094 | LWIP_UNUSED_ARG(dbg_list_name);
|
---|
1095 | LWIP_UNUSED_ARG(dbg_other_seg_list);
|
---|
1096 |
|
---|
1097 | while (seg_list != NULL &&
|
---|
1098 | TCP_SEQ_LEQ(lwip_ntohl(seg_list->tcphdr->seqno) +
|
---|
1099 | TCP_TCPLEN(seg_list), ackno)) {
|
---|
1100 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->%s\n",
|
---|
1101 | lwip_ntohl(seg_list->tcphdr->seqno),
|
---|
1102 | lwip_ntohl(seg_list->tcphdr->seqno) + TCP_TCPLEN(seg_list),
|
---|
1103 | dbg_list_name));
|
---|
1104 |
|
---|
1105 | next = seg_list;
|
---|
1106 | seg_list = seg_list->next;
|
---|
1107 |
|
---|
1108 | clen = pbuf_clen(next->p);
|
---|
1109 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"TCPWNDSIZE_F" ... ",
|
---|
1110 | (tcpwnd_size_t)pcb->snd_queuelen));
|
---|
1111 | LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= clen));
|
---|
1112 |
|
---|
1113 | pcb->snd_queuelen = (u16_t)(pcb->snd_queuelen - clen);
|
---|
1114 | recv_acked = (tcpwnd_size_t)(recv_acked + next->len);
|
---|
1115 | tcp_seg_free(next);
|
---|
1116 |
|
---|
1117 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"TCPWNDSIZE_F" (after freeing %s)\n",
|
---|
1118 | (tcpwnd_size_t)pcb->snd_queuelen,
|
---|
1119 | dbg_list_name));
|
---|
1120 | if (pcb->snd_queuelen != 0) {
|
---|
1121 | LWIP_ASSERT("tcp_receive: valid queue length",
|
---|
1122 | seg_list != NULL || dbg_other_seg_list != NULL);
|
---|
1123 | }
|
---|
1124 | }
|
---|
1125 | return seg_list;
|
---|
1126 | }
|
---|
1127 |
|
---|
1128 | /**
|
---|
1129 | * Called by tcp_process. Checks if the given segment is an ACK for outstanding
|
---|
1130 | * data, and if so frees the memory of the buffered data. Next, it places the
|
---|
1131 | * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
|
---|
1132 | * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
|
---|
1133 | * it has been removed from the buffer.
|
---|
1134 | *
|
---|
1135 | * If the incoming segment constitutes an ACK for a segment that was used for RTT
|
---|
1136 | * estimation, the RTT is estimated here as well.
|
---|
1137 | *
|
---|
1138 | * Called from tcp_process().
|
---|
1139 | */
|
---|
1140 | static void
|
---|
1141 | tcp_receive(struct tcp_pcb *pcb)
|
---|
1142 | {
|
---|
1143 | s16_t m;
|
---|
1144 | u32_t right_wnd_edge;
|
---|
1145 | int found_dupack = 0;
|
---|
1146 |
|
---|
1147 | LWIP_ASSERT("tcp_receive: invalid pcb", pcb != NULL);
|
---|
1148 | LWIP_ASSERT("tcp_receive: wrong state", pcb->state >= ESTABLISHED);
|
---|
1149 |
|
---|
1150 | if (flags & TCP_ACK) {
|
---|
1151 | right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
|
---|
1152 |
|
---|
1153 | /* Update window. */
|
---|
1154 | if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
|
---|
1155 | (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
|
---|
1156 | (pcb->snd_wl2 == ackno && (u32_t)SND_WND_SCALE(pcb, tcphdr->wnd) > pcb->snd_wnd)) {
|
---|
1157 | pcb->snd_wnd = SND_WND_SCALE(pcb, tcphdr->wnd);
|
---|
1158 | /* keep track of the biggest window announced by the remote host to calculate
|
---|
1159 | the maximum segment size */
|
---|
1160 | if (pcb->snd_wnd_max < pcb->snd_wnd) {
|
---|
1161 | pcb->snd_wnd_max = pcb->snd_wnd;
|
---|
1162 | }
|
---|
1163 | pcb->snd_wl1 = seqno;
|
---|
1164 | pcb->snd_wl2 = ackno;
|
---|
1165 | LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"TCPWNDSIZE_F"\n", pcb->snd_wnd));
|
---|
1166 | #if TCP_WND_DEBUG
|
---|
1167 | } else {
|
---|
1168 | if (pcb->snd_wnd != (tcpwnd_size_t)SND_WND_SCALE(pcb, tcphdr->wnd)) {
|
---|
1169 | LWIP_DEBUGF(TCP_WND_DEBUG,
|
---|
1170 | ("tcp_receive: no window update lastack %"U32_F" ackno %"
|
---|
1171 | U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
|
---|
1172 | pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
|
---|
1173 | }
|
---|
1174 | #endif /* TCP_WND_DEBUG */
|
---|
1175 | }
|
---|
1176 |
|
---|
1177 | /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
|
---|
1178 | * duplicate ack if:
|
---|
1179 | * 1) It doesn't ACK new data
|
---|
1180 | * 2) length of received packet is zero (i.e. no payload)
|
---|
1181 | * 3) the advertised window hasn't changed
|
---|
1182 | * 4) There is outstanding unacknowledged data (retransmission timer running)
|
---|
1183 | * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
|
---|
1184 | *
|
---|
1185 | * If it passes all five, should process as a dupack:
|
---|
1186 | * a) dupacks < 3: do nothing
|
---|
1187 | * b) dupacks == 3: fast retransmit
|
---|
1188 | * c) dupacks > 3: increase cwnd
|
---|
1189 | *
|
---|
1190 | * If it only passes 1-3, should reset dupack counter (and add to
|
---|
1191 | * stats, which we don't do in lwIP)
|
---|
1192 | *
|
---|
1193 | * If it only passes 1, should reset dupack counter
|
---|
1194 | *
|
---|
1195 | */
|
---|
1196 |
|
---|
1197 | /* Clause 1 */
|
---|
1198 | if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
|
---|
1199 | /* Clause 2 */
|
---|
1200 | if (tcplen == 0) {
|
---|
1201 | /* Clause 3 */
|
---|
1202 | if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge) {
|
---|
1203 | /* Clause 4 */
|
---|
1204 | if (pcb->rtime >= 0) {
|
---|
1205 | /* Clause 5 */
|
---|
1206 | if (pcb->lastack == ackno) {
|
---|
1207 | found_dupack = 1;
|
---|
1208 | if ((u8_t)(pcb->dupacks + 1) > pcb->dupacks) {
|
---|
1209 | ++pcb->dupacks;
|
---|
1210 | }
|
---|
1211 | if (pcb->dupacks > 3) {
|
---|
1212 | /* Inflate the congestion window */
|
---|
1213 | TCP_WND_INC(pcb->cwnd, pcb->mss);
|
---|
1214 | }
|
---|
1215 | if (pcb->dupacks >= 3) {
|
---|
1216 | /* Do fast retransmit (checked via TF_INFR, not via dupacks count) */
|
---|
1217 | tcp_rexmit_fast(pcb);
|
---|
1218 | }
|
---|
1219 | }
|
---|
1220 | }
|
---|
1221 | }
|
---|
1222 | }
|
---|
1223 | /* If Clause (1) or more is true, but not a duplicate ack, reset
|
---|
1224 | * count of consecutive duplicate acks */
|
---|
1225 | if (!found_dupack) {
|
---|
1226 | pcb->dupacks = 0;
|
---|
1227 | }
|
---|
1228 | } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack + 1, pcb->snd_nxt)) {
|
---|
1229 | /* We come here when the ACK acknowledges new data. */
|
---|
1230 | tcpwnd_size_t acked;
|
---|
1231 |
|
---|
1232 | /* Reset the "IN Fast Retransmit" flag, since we are no longer
|
---|
1233 | in fast retransmit. Also reset the congestion window to the
|
---|
1234 | slow start threshold. */
|
---|
1235 | if (pcb->flags & TF_INFR) {
|
---|
1236 | tcp_clear_flags(pcb, TF_INFR);
|
---|
1237 | pcb->cwnd = pcb->ssthresh;
|
---|
1238 | pcb->bytes_acked = 0;
|
---|
1239 | }
|
---|
1240 |
|
---|
1241 | /* Reset the number of retransmissions. */
|
---|
1242 | pcb->nrtx = 0;
|
---|
1243 |
|
---|
1244 | /* Reset the retransmission time-out. */
|
---|
1245 | pcb->rto = (s16_t)((pcb->sa >> 3) + pcb->sv);
|
---|
1246 |
|
---|
1247 | /* Record how much data this ACK acks */
|
---|
1248 | acked = (tcpwnd_size_t)(ackno - pcb->lastack);
|
---|
1249 |
|
---|
1250 | /* Reset the fast retransmit variables. */
|
---|
1251 | pcb->dupacks = 0;
|
---|
1252 | pcb->lastack = ackno;
|
---|
1253 |
|
---|
1254 | /* Update the congestion control variables (cwnd and
|
---|
1255 | ssthresh). */
|
---|
1256 | if (pcb->state >= ESTABLISHED) {
|
---|
1257 | if (pcb->cwnd < pcb->ssthresh) {
|
---|
1258 | tcpwnd_size_t increase;
|
---|
1259 | /* limit to 1 SMSS segment during period following RTO */
|
---|
1260 | u8_t num_seg = (pcb->flags & TF_RTO) ? 1 : 2;
|
---|
1261 | /* RFC 3465, section 2.2 Slow Start */
|
---|
1262 | increase = LWIP_MIN(acked, (tcpwnd_size_t)(num_seg * pcb->mss));
|
---|
1263 | TCP_WND_INC(pcb->cwnd, increase);
|
---|
1264 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"TCPWNDSIZE_F"\n", pcb->cwnd));
|
---|
1265 | } else {
|
---|
1266 | /* RFC 3465, section 2.1 Congestion Avoidance */
|
---|
1267 | TCP_WND_INC(pcb->bytes_acked, acked);
|
---|
1268 | if (pcb->bytes_acked >= pcb->cwnd) {
|
---|
1269 | pcb->bytes_acked = (tcpwnd_size_t)(pcb->bytes_acked - pcb->cwnd);
|
---|
1270 | TCP_WND_INC(pcb->cwnd, pcb->mss);
|
---|
1271 | }
|
---|
1272 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"TCPWNDSIZE_F"\n", pcb->cwnd));
|
---|
1273 | }
|
---|
1274 | }
|
---|
1275 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
|
---|
1276 | ackno,
|
---|
1277 | pcb->unacked != NULL ?
|
---|
1278 | lwip_ntohl(pcb->unacked->tcphdr->seqno) : 0,
|
---|
1279 | pcb->unacked != NULL ?
|
---|
1280 | lwip_ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked) : 0));
|
---|
1281 |
|
---|
1282 | /* Remove segment from the unacknowledged list if the incoming
|
---|
1283 | ACK acknowledges them. */
|
---|
1284 | pcb->unacked = tcp_free_acked_segments(pcb, pcb->unacked, "unacked", pcb->unsent);
|
---|
1285 | /* We go through the ->unsent list to see if any of the segments
|
---|
1286 | on the list are acknowledged by the ACK. This may seem
|
---|
1287 | strange since an "unsent" segment shouldn't be acked. The
|
---|
1288 | rationale is that lwIP puts all outstanding segments on the
|
---|
1289 | ->unsent list after a retransmission, so these segments may
|
---|
1290 | in fact have been sent once. */
|
---|
1291 | pcb->unsent = tcp_free_acked_segments(pcb, pcb->unsent, "unsent", pcb->unacked);
|
---|
1292 |
|
---|
1293 | /* If there's nothing left to acknowledge, stop the retransmit
|
---|
1294 | timer, otherwise reset it to start again */
|
---|
1295 | if (pcb->unacked == NULL) {
|
---|
1296 | pcb->rtime = -1;
|
---|
1297 | } else {
|
---|
1298 | pcb->rtime = 0;
|
---|
1299 | }
|
---|
1300 |
|
---|
1301 | pcb->polltmr = 0;
|
---|
1302 |
|
---|
1303 | #if TCP_OVERSIZE
|
---|
1304 | if (pcb->unsent == NULL) {
|
---|
1305 | pcb->unsent_oversize = 0;
|
---|
1306 | }
|
---|
1307 | #endif /* TCP_OVERSIZE */
|
---|
1308 |
|
---|
1309 | #if LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS
|
---|
1310 | if (ip_current_is_v6()) {
|
---|
1311 | /* Inform neighbor reachability of forward progress. */
|
---|
1312 | nd6_reachability_hint(ip6_current_src_addr());
|
---|
1313 | }
|
---|
1314 | #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/
|
---|
1315 |
|
---|
1316 | pcb->snd_buf = (tcpwnd_size_t)(pcb->snd_buf + recv_acked);
|
---|
1317 | /* check if this ACK ends our retransmission of in-flight data */
|
---|
1318 | if (pcb->flags & TF_RTO) {
|
---|
1319 | /* RTO is done if
|
---|
1320 | 1) both queues are empty or
|
---|
1321 | 2) unacked is empty and unsent head contains data not part of RTO or
|
---|
1322 | 3) unacked head contains data not part of RTO */
|
---|
1323 | if (pcb->unacked == NULL) {
|
---|
1324 | if ((pcb->unsent == NULL) ||
|
---|
1325 | (TCP_SEQ_LEQ(pcb->rto_end, lwip_ntohl(pcb->unsent->tcphdr->seqno)))) {
|
---|
1326 | tcp_clear_flags(pcb, TF_RTO);
|
---|
1327 | }
|
---|
1328 | } else if (TCP_SEQ_LEQ(pcb->rto_end, lwip_ntohl(pcb->unacked->tcphdr->seqno))) {
|
---|
1329 | tcp_clear_flags(pcb, TF_RTO);
|
---|
1330 | }
|
---|
1331 | }
|
---|
1332 | /* End of ACK for new data processing. */
|
---|
1333 | } else {
|
---|
1334 | /* Out of sequence ACK, didn't really ack anything */
|
---|
1335 | tcp_send_empty_ack(pcb);
|
---|
1336 | }
|
---|
1337 |
|
---|
1338 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
|
---|
1339 | pcb->rttest, pcb->rtseq, ackno));
|
---|
1340 |
|
---|
1341 | /* RTT estimation calculations. This is done by checking if the
|
---|
1342 | incoming segment acknowledges the segment we use to take a
|
---|
1343 | round-trip time measurement. */
|
---|
1344 | if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
|
---|
1345 | /* diff between this shouldn't exceed 32K since this are tcp timer ticks
|
---|
1346 | and a round-trip shouldn't be that long... */
|
---|
1347 | m = (s16_t)(tcp_ticks - pcb->rttest);
|
---|
1348 |
|
---|
1349 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
|
---|
1350 | m, (u16_t)(m * TCP_SLOW_INTERVAL)));
|
---|
1351 |
|
---|
1352 | /* This is taken directly from VJs original code in his paper */
|
---|
1353 | m = (s16_t)(m - (pcb->sa >> 3));
|
---|
1354 | pcb->sa = (s16_t)(pcb->sa + m);
|
---|
1355 | if (m < 0) {
|
---|
1356 | m = (s16_t) - m;
|
---|
1357 | }
|
---|
1358 | m = (s16_t)(m - (pcb->sv >> 2));
|
---|
1359 | pcb->sv = (s16_t)(pcb->sv + m);
|
---|
1360 | pcb->rto = (s16_t)((pcb->sa >> 3) + pcb->sv);
|
---|
1361 |
|
---|
1362 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
|
---|
1363 | pcb->rto, (u16_t)(pcb->rto * TCP_SLOW_INTERVAL)));
|
---|
1364 |
|
---|
1365 | pcb->rttest = 0;
|
---|
1366 | }
|
---|
1367 | }
|
---|
1368 |
|
---|
1369 | /* If the incoming segment contains data, we must process it
|
---|
1370 | further unless the pcb already received a FIN.
|
---|
1371 | (RFC 793, chapter 3.9, "SEGMENT ARRIVES" in states CLOSE-WAIT, CLOSING,
|
---|
1372 | LAST-ACK and TIME-WAIT: "Ignore the segment text.") */
|
---|
1373 | if ((tcplen > 0) && (pcb->state < CLOSE_WAIT)) {
|
---|
1374 | /* This code basically does three things:
|
---|
1375 |
|
---|
1376 | +) If the incoming segment contains data that is the next
|
---|
1377 | in-sequence data, this data is passed to the application. This
|
---|
1378 | might involve trimming the first edge of the data. The rcv_nxt
|
---|
1379 | variable and the advertised window are adjusted.
|
---|
1380 |
|
---|
1381 | +) If the incoming segment has data that is above the next
|
---|
1382 | sequence number expected (->rcv_nxt), the segment is placed on
|
---|
1383 | the ->ooseq queue. This is done by finding the appropriate
|
---|
1384 | place in the ->ooseq queue (which is ordered by sequence
|
---|
1385 | number) and trim the segment in both ends if needed. An
|
---|
1386 | immediate ACK is sent to indicate that we received an
|
---|
1387 | out-of-sequence segment.
|
---|
1388 |
|
---|
1389 | +) Finally, we check if the first segment on the ->ooseq queue
|
---|
1390 | now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
|
---|
1391 | rcv_nxt > ooseq->seqno, we must trim the first edge of the
|
---|
1392 | segment on ->ooseq before we adjust rcv_nxt. The data in the
|
---|
1393 | segments that are now on sequence are chained onto the
|
---|
1394 | incoming segment so that we only need to call the application
|
---|
1395 | once.
|
---|
1396 | */
|
---|
1397 |
|
---|
1398 | /* First, we check if we must trim the first edge. We have to do
|
---|
1399 | this if the sequence number of the incoming segment is less
|
---|
1400 | than rcv_nxt, and the sequence number plus the length of the
|
---|
1401 | segment is larger than rcv_nxt. */
|
---|
1402 | /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)) {
|
---|
1403 | if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
|
---|
1404 | if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)) {
|
---|
1405 | /* Trimming the first edge is done by pushing the payload
|
---|
1406 | pointer in the pbuf downwards. This is somewhat tricky since
|
---|
1407 | we do not want to discard the full contents of the pbuf up to
|
---|
1408 | the new starting point of the data since we have to keep the
|
---|
1409 | TCP header which is present in the first pbuf in the chain.
|
---|
1410 |
|
---|
1411 | What is done is really quite a nasty hack: the first pbuf in
|
---|
1412 | the pbuf chain is pointed to by inseg.p. Since we need to be
|
---|
1413 | able to deallocate the whole pbuf, we cannot change this
|
---|
1414 | inseg.p pointer to point to any of the later pbufs in the
|
---|
1415 | chain. Instead, we point the ->payload pointer in the first
|
---|
1416 | pbuf to data in one of the later pbufs. We also set the
|
---|
1417 | inseg.data pointer to point to the right place. This way, the
|
---|
1418 | ->p pointer will still point to the first pbuf, but the
|
---|
1419 | ->p->payload pointer will point to data in another pbuf.
|
---|
1420 |
|
---|
1421 | After we are done with adjusting the pbuf pointers we must
|
---|
1422 | adjust the ->data pointer in the seg and the segment
|
---|
1423 | length.*/
|
---|
1424 |
|
---|
1425 | struct pbuf *p = inseg.p;
|
---|
1426 | u32_t off32 = pcb->rcv_nxt - seqno;
|
---|
1427 | u16_t new_tot_len, off;
|
---|
1428 | LWIP_ASSERT("inseg.p != NULL", inseg.p);
|
---|
1429 | LWIP_ASSERT("insane offset!", (off32 < 0xffff));
|
---|
1430 | off = (u16_t)off32;
|
---|
1431 | LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
|
---|
1432 | inseg.len -= off;
|
---|
1433 | new_tot_len = (u16_t)(inseg.p->tot_len - off);
|
---|
1434 | while (p->len < off) {
|
---|
1435 | off -= p->len;
|
---|
1436 | /* all pbufs up to and including this one have len==0, so tot_len is equal */
|
---|
1437 | p->tot_len = new_tot_len;
|
---|
1438 | p->len = 0;
|
---|
1439 | p = p->next;
|
---|
1440 | }
|
---|
1441 | /* cannot fail... */
|
---|
1442 | pbuf_remove_header(p, off);
|
---|
1443 | inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
|
---|
1444 | } else {
|
---|
1445 | if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)) {
|
---|
1446 | /* the whole segment is < rcv_nxt */
|
---|
1447 | /* must be a duplicate of a packet that has already been correctly handled */
|
---|
1448 |
|
---|
1449 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
|
---|
1450 | tcp_ack_now(pcb);
|
---|
1451 | }
|
---|
1452 | }
|
---|
1453 |
|
---|
1454 | /* The sequence number must be within the window (above rcv_nxt
|
---|
1455 | and below rcv_nxt + rcv_wnd) in order to be further
|
---|
1456 | processed. */
|
---|
1457 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
---|
1458 | pcb->rcv_nxt + pcb->rcv_wnd - 1)) {
|
---|
1459 | if (pcb->rcv_nxt == seqno) {
|
---|
1460 | /* The incoming segment is the next in sequence. We check if
|
---|
1461 | we have to trim the end of the segment and update rcv_nxt
|
---|
1462 | and pass the data to the application. */
|
---|
1463 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1464 |
|
---|
1465 | if (tcplen > pcb->rcv_wnd) {
|
---|
1466 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
1467 | ("tcp_receive: other end overran receive window"
|
---|
1468 | "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
|
---|
1469 | seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1470 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
1471 | /* Must remove the FIN from the header as we're trimming
|
---|
1472 | * that byte of sequence-space from the packet */
|
---|
1473 | TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) & ~(unsigned int)TCP_FIN);
|
---|
1474 | }
|
---|
1475 | /* Adjust length of segment to fit in the window. */
|
---|
1476 | TCPWND_CHECK16(pcb->rcv_wnd);
|
---|
1477 | inseg.len = (u16_t)pcb->rcv_wnd;
|
---|
1478 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
---|
1479 | inseg.len -= 1;
|
---|
1480 | }
|
---|
1481 | pbuf_realloc(inseg.p, inseg.len);
|
---|
1482 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1483 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
---|
1484 | (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1485 | }
|
---|
1486 | #if TCP_QUEUE_OOSEQ
|
---|
1487 | /* Received in-sequence data, adjust ooseq data if:
|
---|
1488 | - FIN has been received or
|
---|
1489 | - inseq overlaps with ooseq */
|
---|
1490 | if (pcb->ooseq != NULL) {
|
---|
1491 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
1492 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
1493 | ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
|
---|
1494 | /* Received in-order FIN means anything that was received
|
---|
1495 | * out of order must now have been received in-order, so
|
---|
1496 | * bin the ooseq queue */
|
---|
1497 | while (pcb->ooseq != NULL) {
|
---|
1498 | struct tcp_seg *old_ooseq = pcb->ooseq;
|
---|
1499 | pcb->ooseq = pcb->ooseq->next;
|
---|
1500 | tcp_seg_free(old_ooseq);
|
---|
1501 | }
|
---|
1502 | } else {
|
---|
1503 | struct tcp_seg *next = pcb->ooseq;
|
---|
1504 | /* Remove all segments on ooseq that are covered by inseg already.
|
---|
1505 | * FIN is copied from ooseq to inseg if present. */
|
---|
1506 | while (next &&
|
---|
1507 | TCP_SEQ_GEQ(seqno + tcplen,
|
---|
1508 | next->tcphdr->seqno + next->len)) {
|
---|
1509 | struct tcp_seg *tmp;
|
---|
1510 | /* inseg cannot have FIN here (already processed above) */
|
---|
1511 | if ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0 &&
|
---|
1512 | (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
|
---|
1513 | TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
|
---|
1514 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1515 | }
|
---|
1516 | tmp = next;
|
---|
1517 | next = next->next;
|
---|
1518 | tcp_seg_free(tmp);
|
---|
1519 | }
|
---|
1520 | /* Now trim right side of inseg if it overlaps with the first
|
---|
1521 | * segment on ooseq */
|
---|
1522 | if (next &&
|
---|
1523 | TCP_SEQ_GT(seqno + tcplen,
|
---|
1524 | next->tcphdr->seqno)) {
|
---|
1525 | /* inseg cannot have FIN here (already processed above) */
|
---|
1526 | inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
|
---|
1527 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
---|
1528 | inseg.len -= 1;
|
---|
1529 | }
|
---|
1530 | pbuf_realloc(inseg.p, inseg.len);
|
---|
1531 | tcplen = TCP_TCPLEN(&inseg);
|
---|
1532 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
|
---|
1533 | (seqno + tcplen) == next->tcphdr->seqno);
|
---|
1534 | }
|
---|
1535 | pcb->ooseq = next;
|
---|
1536 | }
|
---|
1537 | }
|
---|
1538 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1539 |
|
---|
1540 | pcb->rcv_nxt = seqno + tcplen;
|
---|
1541 |
|
---|
1542 | /* Update the receiver's (our) window. */
|
---|
1543 | LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
|
---|
1544 | pcb->rcv_wnd -= tcplen;
|
---|
1545 |
|
---|
1546 | tcp_update_rcv_ann_wnd(pcb);
|
---|
1547 |
|
---|
1548 | /* If there is data in the segment, we make preparations to
|
---|
1549 | pass this up to the application. The ->recv_data variable
|
---|
1550 | is used for holding the pbuf that goes to the
|
---|
1551 | application. The code for reassembling out-of-sequence data
|
---|
1552 | chains its data on this pbuf as well.
|
---|
1553 |
|
---|
1554 | If the segment was a FIN, we set the TF_GOT_FIN flag that will
|
---|
1555 | be used to indicate to the application that the remote side has
|
---|
1556 | closed its end of the connection. */
|
---|
1557 | if (inseg.p->tot_len > 0) {
|
---|
1558 | recv_data = inseg.p;
|
---|
1559 | /* Since this pbuf now is the responsibility of the
|
---|
1560 | application, we delete our reference to it so that we won't
|
---|
1561 | (mistakingly) deallocate it. */
|
---|
1562 | inseg.p = NULL;
|
---|
1563 | }
|
---|
1564 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
1565 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
|
---|
1566 | recv_flags |= TF_GOT_FIN;
|
---|
1567 | }
|
---|
1568 |
|
---|
1569 | #if TCP_QUEUE_OOSEQ
|
---|
1570 | /* We now check if we have segments on the ->ooseq queue that
|
---|
1571 | are now in sequence. */
|
---|
1572 | while (pcb->ooseq != NULL &&
|
---|
1573 | pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
|
---|
1574 |
|
---|
1575 | struct tcp_seg *cseg = pcb->ooseq;
|
---|
1576 | seqno = pcb->ooseq->tcphdr->seqno;
|
---|
1577 |
|
---|
1578 | pcb->rcv_nxt += TCP_TCPLEN(cseg);
|
---|
1579 | LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
|
---|
1580 | pcb->rcv_wnd >= TCP_TCPLEN(cseg));
|
---|
1581 | pcb->rcv_wnd -= TCP_TCPLEN(cseg);
|
---|
1582 |
|
---|
1583 | tcp_update_rcv_ann_wnd(pcb);
|
---|
1584 |
|
---|
1585 | if (cseg->p->tot_len > 0) {
|
---|
1586 | /* Chain this pbuf onto the pbuf that we will pass to
|
---|
1587 | the application. */
|
---|
1588 | /* With window scaling, this can overflow recv_data->tot_len, but
|
---|
1589 | that's not a problem since we explicitly fix that before passing
|
---|
1590 | recv_data to the application. */
|
---|
1591 | if (recv_data) {
|
---|
1592 | pbuf_cat(recv_data, cseg->p);
|
---|
1593 | } else {
|
---|
1594 | recv_data = cseg->p;
|
---|
1595 | }
|
---|
1596 | cseg->p = NULL;
|
---|
1597 | }
|
---|
1598 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
---|
1599 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
|
---|
1600 | recv_flags |= TF_GOT_FIN;
|
---|
1601 | if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
|
---|
1602 | pcb->state = CLOSE_WAIT;
|
---|
1603 | }
|
---|
1604 | }
|
---|
1605 |
|
---|
1606 | pcb->ooseq = cseg->next;
|
---|
1607 | tcp_seg_free(cseg);
|
---|
1608 | }
|
---|
1609 | #if LWIP_TCP_SACK_OUT
|
---|
1610 | if (pcb->flags & TF_SACK) {
|
---|
1611 | if (pcb->ooseq != NULL) {
|
---|
1612 | /* Some segments may have been removed from ooseq, let's remove all SACKs that
|
---|
1613 | describe anything before the new beginning of that list. */
|
---|
1614 | tcp_remove_sacks_lt(pcb, pcb->ooseq->tcphdr->seqno);
|
---|
1615 | } else if (LWIP_TCP_SACK_VALID(pcb, 0)) {
|
---|
1616 | /* ooseq has been cleared. Nothing to SACK */
|
---|
1617 | memset(pcb->rcv_sacks, 0, sizeof(pcb->rcv_sacks));
|
---|
1618 | }
|
---|
1619 | }
|
---|
1620 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1621 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1622 |
|
---|
1623 |
|
---|
1624 | /* Acknowledge the segment(s). */
|
---|
1625 | tcp_ack(pcb);
|
---|
1626 |
|
---|
1627 | #if LWIP_TCP_SACK_OUT
|
---|
1628 | if (LWIP_TCP_SACK_VALID(pcb, 0)) {
|
---|
1629 | /* Normally the ACK for the data received could be piggy-backed on a data packet,
|
---|
1630 | but lwIP currently does not support including SACKs in data packets. So we force
|
---|
1631 | it to respond with an empty ACK packet (only if there is at least one SACK to be sent).
|
---|
1632 | NOTE: tcp_send_empty_ack() on success clears the ACK flags (set by tcp_ack()) */
|
---|
1633 | tcp_send_empty_ack(pcb);
|
---|
1634 | }
|
---|
1635 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1636 |
|
---|
1637 | #if LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS
|
---|
1638 | if (ip_current_is_v6()) {
|
---|
1639 | /* Inform neighbor reachability of forward progress. */
|
---|
1640 | nd6_reachability_hint(ip6_current_src_addr());
|
---|
1641 | }
|
---|
1642 | #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/
|
---|
1643 |
|
---|
1644 | } else {
|
---|
1645 | /* We get here if the incoming segment is out-of-sequence. */
|
---|
1646 |
|
---|
1647 | #if TCP_QUEUE_OOSEQ
|
---|
1648 | /* We queue the segment on the ->ooseq queue. */
|
---|
1649 | if (pcb->ooseq == NULL) {
|
---|
1650 | pcb->ooseq = tcp_seg_copy(&inseg);
|
---|
1651 | #if LWIP_TCP_SACK_OUT
|
---|
1652 | if (pcb->flags & TF_SACK) {
|
---|
1653 | /* All the SACKs should be invalid, so we can simply store the most recent one: */
|
---|
1654 | pcb->rcv_sacks[0].left = seqno;
|
---|
1655 | pcb->rcv_sacks[0].right = seqno + inseg.len;
|
---|
1656 | }
|
---|
1657 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1658 | } else {
|
---|
1659 | /* If the queue is not empty, we walk through the queue and
|
---|
1660 | try to find a place where the sequence number of the
|
---|
1661 | incoming segment is between the sequence numbers of the
|
---|
1662 | previous and the next segment on the ->ooseq queue. That is
|
---|
1663 | the place where we put the incoming segment. If needed, we
|
---|
1664 | trim the second edges of the previous and the incoming
|
---|
1665 | segment so that it will fit into the sequence.
|
---|
1666 |
|
---|
1667 | If the incoming segment has the same sequence number as a
|
---|
1668 | segment on the ->ooseq queue, we discard the segment that
|
---|
1669 | contains less data. */
|
---|
1670 |
|
---|
1671 | #if LWIP_TCP_SACK_OUT
|
---|
1672 | /* This is the left edge of the lowest possible SACK range.
|
---|
1673 | It may start before the newly received segment (possibly adjusted below). */
|
---|
1674 | u32_t sackbeg = TCP_SEQ_LT(seqno, pcb->ooseq->tcphdr->seqno) ? seqno : pcb->ooseq->tcphdr->seqno;
|
---|
1675 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1676 | struct tcp_seg *next, *prev = NULL;
|
---|
1677 | for (next = pcb->ooseq; next != NULL; next = next->next) {
|
---|
1678 | if (seqno == next->tcphdr->seqno) {
|
---|
1679 | /* The sequence number of the incoming segment is the
|
---|
1680 | same as the sequence number of the segment on
|
---|
1681 | ->ooseq. We check the lengths to see which one to
|
---|
1682 | discard. */
|
---|
1683 | if (inseg.len > next->len) {
|
---|
1684 | /* The incoming segment is larger than the old
|
---|
1685 | segment. We replace some segments with the new
|
---|
1686 | one. */
|
---|
1687 | struct tcp_seg *cseg = tcp_seg_copy(&inseg);
|
---|
1688 | if (cseg != NULL) {
|
---|
1689 | if (prev != NULL) {
|
---|
1690 | prev->next = cseg;
|
---|
1691 | } else {
|
---|
1692 | pcb->ooseq = cseg;
|
---|
1693 | }
|
---|
1694 | tcp_oos_insert_segment(cseg, next);
|
---|
1695 | }
|
---|
1696 | break;
|
---|
1697 | } else {
|
---|
1698 | /* Either the lengths are the same or the incoming
|
---|
1699 | segment was smaller than the old one; in either
|
---|
1700 | case, we ditch the incoming segment. */
|
---|
1701 | break;
|
---|
1702 | }
|
---|
1703 | } else {
|
---|
1704 | if (prev == NULL) {
|
---|
1705 | if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
|
---|
1706 | /* The sequence number of the incoming segment is lower
|
---|
1707 | than the sequence number of the first segment on the
|
---|
1708 | queue. We put the incoming segment first on the
|
---|
1709 | queue. */
|
---|
1710 | struct tcp_seg *cseg = tcp_seg_copy(&inseg);
|
---|
1711 | if (cseg != NULL) {
|
---|
1712 | pcb->ooseq = cseg;
|
---|
1713 | tcp_oos_insert_segment(cseg, next);
|
---|
1714 | }
|
---|
1715 | break;
|
---|
1716 | }
|
---|
1717 | } else {
|
---|
1718 | /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
|
---|
1719 | TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
|
---|
1720 | if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno + 1, next->tcphdr->seqno - 1)) {
|
---|
1721 | /* The sequence number of the incoming segment is in
|
---|
1722 | between the sequence numbers of the previous and
|
---|
1723 | the next segment on ->ooseq. We trim trim the previous
|
---|
1724 | segment, delete next segments that included in received segment
|
---|
1725 | and trim received, if needed. */
|
---|
1726 | struct tcp_seg *cseg = tcp_seg_copy(&inseg);
|
---|
1727 | if (cseg != NULL) {
|
---|
1728 | if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
|
---|
1729 | /* We need to trim the prev segment. */
|
---|
1730 | prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
|
---|
1731 | pbuf_realloc(prev->p, prev->len);
|
---|
1732 | }
|
---|
1733 | prev->next = cseg;
|
---|
1734 | tcp_oos_insert_segment(cseg, next);
|
---|
1735 | }
|
---|
1736 | break;
|
---|
1737 | }
|
---|
1738 | }
|
---|
1739 |
|
---|
1740 | #if LWIP_TCP_SACK_OUT
|
---|
1741 | /* The new segment goes after the 'next' one. If there is a "hole" in sequence numbers
|
---|
1742 | between 'prev' and the beginning of 'next', we want to move sackbeg. */
|
---|
1743 | if (prev != NULL && prev->tcphdr->seqno + prev->len != next->tcphdr->seqno) {
|
---|
1744 | sackbeg = next->tcphdr->seqno;
|
---|
1745 | }
|
---|
1746 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1747 |
|
---|
1748 | /* We don't use 'prev' below, so let's set it to current 'next'.
|
---|
1749 | This way even if we break the loop below, 'prev' will be pointing
|
---|
1750 | at the segment right in front of the newly added one. */
|
---|
1751 | prev = next;
|
---|
1752 |
|
---|
1753 | /* If the "next" segment is the last segment on the
|
---|
1754 | ooseq queue, we add the incoming segment to the end
|
---|
1755 | of the list. */
|
---|
1756 | if (next->next == NULL &&
|
---|
1757 | TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
|
---|
1758 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
---|
1759 | /* segment "next" already contains all data */
|
---|
1760 | break;
|
---|
1761 | }
|
---|
1762 | next->next = tcp_seg_copy(&inseg);
|
---|
1763 | if (next->next != NULL) {
|
---|
1764 | if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
|
---|
1765 | /* We need to trim the last segment. */
|
---|
1766 | next->len = (u16_t)(seqno - next->tcphdr->seqno);
|
---|
1767 | pbuf_realloc(next->p, next->len);
|
---|
1768 | }
|
---|
1769 | /* check if the remote side overruns our receive window */
|
---|
1770 | if (TCP_SEQ_GT((u32_t)tcplen + seqno, pcb->rcv_nxt + (u32_t)pcb->rcv_wnd)) {
|
---|
1771 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
1772 | ("tcp_receive: other end overran receive window"
|
---|
1773 | "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
|
---|
1774 | seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1775 | if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
|
---|
1776 | /* Must remove the FIN from the header as we're trimming
|
---|
1777 | * that byte of sequence-space from the packet */
|
---|
1778 | TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) & ~TCP_FIN);
|
---|
1779 | }
|
---|
1780 | /* Adjust length of segment to fit in the window. */
|
---|
1781 | next->next->len = (u16_t)(pcb->rcv_nxt + pcb->rcv_wnd - seqno);
|
---|
1782 | pbuf_realloc(next->next->p, next->next->len);
|
---|
1783 | tcplen = TCP_TCPLEN(next->next);
|
---|
1784 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
---|
1785 | (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
1786 | }
|
---|
1787 | }
|
---|
1788 | break;
|
---|
1789 | }
|
---|
1790 | }
|
---|
1791 | }
|
---|
1792 |
|
---|
1793 | #if LWIP_TCP_SACK_OUT
|
---|
1794 | if (pcb->flags & TF_SACK) {
|
---|
1795 | if (prev == NULL) {
|
---|
1796 | /* The new segment is at the beginning. sackbeg should already be set properly.
|
---|
1797 | We need to find the right edge. */
|
---|
1798 | next = pcb->ooseq;
|
---|
1799 | } else if (prev->next != NULL) {
|
---|
1800 | /* The new segment was added after 'prev'. If there is a "hole" between 'prev' and 'prev->next',
|
---|
1801 | we need to move sackbeg. After that we should find the right edge. */
|
---|
1802 | next = prev->next;
|
---|
1803 | if (prev->tcphdr->seqno + prev->len != next->tcphdr->seqno) {
|
---|
1804 | sackbeg = next->tcphdr->seqno;
|
---|
1805 | }
|
---|
1806 | } else {
|
---|
1807 | next = NULL;
|
---|
1808 | }
|
---|
1809 | if (next != NULL) {
|
---|
1810 | u32_t sackend = next->tcphdr->seqno;
|
---|
1811 | for ( ; (next != NULL) && (sackend == next->tcphdr->seqno); next = next->next) {
|
---|
1812 | sackend += next->len;
|
---|
1813 | }
|
---|
1814 | tcp_add_sack(pcb, sackbeg, sackend);
|
---|
1815 | }
|
---|
1816 | }
|
---|
1817 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1818 | }
|
---|
1819 | #if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
|
---|
1820 | {
|
---|
1821 | /* Check that the data on ooseq doesn't exceed one of the limits
|
---|
1822 | and throw away everything above that limit. */
|
---|
1823 | #ifdef TCP_OOSEQ_BYTES_LIMIT
|
---|
1824 | const u32_t ooseq_max_blen = TCP_OOSEQ_BYTES_LIMIT(pcb);
|
---|
1825 | u32_t ooseq_blen = 0;
|
---|
1826 | #endif
|
---|
1827 | #ifdef TCP_OOSEQ_PBUFS_LIMIT
|
---|
1828 | const u16_t ooseq_max_qlen = TCP_OOSEQ_PBUFS_LIMIT(pcb);
|
---|
1829 | u16_t ooseq_qlen = 0;
|
---|
1830 | #endif
|
---|
1831 | struct tcp_seg *next, *prev = NULL;
|
---|
1832 | for (next = pcb->ooseq; next != NULL; prev = next, next = next->next) {
|
---|
1833 | struct pbuf *p = next->p;
|
---|
1834 | int stop_here = 0;
|
---|
1835 | #ifdef TCP_OOSEQ_BYTES_LIMIT
|
---|
1836 | ooseq_blen += p->tot_len;
|
---|
1837 | if (ooseq_blen > ooseq_max_blen) {
|
---|
1838 | stop_here = 1;
|
---|
1839 | }
|
---|
1840 | #endif
|
---|
1841 | #ifdef TCP_OOSEQ_PBUFS_LIMIT
|
---|
1842 | ooseq_qlen += pbuf_clen(p);
|
---|
1843 | if (ooseq_qlen > ooseq_max_qlen) {
|
---|
1844 | stop_here = 1;
|
---|
1845 | }
|
---|
1846 | #endif
|
---|
1847 | if (stop_here) {
|
---|
1848 | #if LWIP_TCP_SACK_OUT
|
---|
1849 | if (pcb->flags & TF_SACK) {
|
---|
1850 | /* Let's remove all SACKs from next's seqno up. */
|
---|
1851 | tcp_remove_sacks_gt(pcb, next->tcphdr->seqno);
|
---|
1852 | }
|
---|
1853 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1854 | /* too much ooseq data, dump this and everything after it */
|
---|
1855 | tcp_segs_free(next);
|
---|
1856 | if (prev == NULL) {
|
---|
1857 | /* first ooseq segment is too much, dump the whole queue */
|
---|
1858 | pcb->ooseq = NULL;
|
---|
1859 | } else {
|
---|
1860 | /* just dump 'next' and everything after it */
|
---|
1861 | prev->next = NULL;
|
---|
1862 | }
|
---|
1863 | break;
|
---|
1864 | }
|
---|
1865 | }
|
---|
1866 | }
|
---|
1867 | #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
|
---|
1868 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
1869 |
|
---|
1870 | /* We send the ACK packet after we've (potentially) dealt with SACKs,
|
---|
1871 | so they can be included in the acknowledgment. */
|
---|
1872 | tcp_send_empty_ack(pcb);
|
---|
1873 | }
|
---|
1874 | } else {
|
---|
1875 | /* The incoming segment is not within the window. */
|
---|
1876 | tcp_send_empty_ack(pcb);
|
---|
1877 | }
|
---|
1878 | } else {
|
---|
1879 | /* Segments with length 0 is taken care of here. Segments that
|
---|
1880 | fall out of the window are ACKed. */
|
---|
1881 | if (!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd - 1)) {
|
---|
1882 | tcp_ack_now(pcb);
|
---|
1883 | }
|
---|
1884 | }
|
---|
1885 | }
|
---|
1886 |
|
---|
1887 | static u8_t
|
---|
1888 | tcp_get_next_optbyte(void)
|
---|
1889 | {
|
---|
1890 | u16_t optidx = tcp_optidx++;
|
---|
1891 | if ((tcphdr_opt2 == NULL) || (optidx < tcphdr_opt1len)) {
|
---|
1892 | u8_t *opts = (u8_t *)tcphdr + TCP_HLEN;
|
---|
1893 | return opts[optidx];
|
---|
1894 | } else {
|
---|
1895 | u8_t idx = (u8_t)(optidx - tcphdr_opt1len);
|
---|
1896 | return tcphdr_opt2[idx];
|
---|
1897 | }
|
---|
1898 | }
|
---|
1899 |
|
---|
1900 | /**
|
---|
1901 | * Parses the options contained in the incoming segment.
|
---|
1902 | *
|
---|
1903 | * Called from tcp_listen_input() and tcp_process().
|
---|
1904 | * Currently, only the MSS option is supported!
|
---|
1905 | *
|
---|
1906 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
1907 | */
|
---|
1908 | static void
|
---|
1909 | tcp_parseopt(struct tcp_pcb *pcb)
|
---|
1910 | {
|
---|
1911 | u8_t data;
|
---|
1912 | u16_t mss;
|
---|
1913 | #if LWIP_TCP_TIMESTAMPS
|
---|
1914 | u32_t tsval;
|
---|
1915 | #endif
|
---|
1916 |
|
---|
1917 | LWIP_ASSERT("tcp_parseopt: invalid pcb", pcb != NULL);
|
---|
1918 |
|
---|
1919 | /* Parse the TCP MSS option, if present. */
|
---|
1920 | if (tcphdr_optlen != 0) {
|
---|
1921 | for (tcp_optidx = 0; tcp_optidx < tcphdr_optlen; ) {
|
---|
1922 | u8_t opt = tcp_get_next_optbyte();
|
---|
1923 | switch (opt) {
|
---|
1924 | case LWIP_TCP_OPT_EOL:
|
---|
1925 | /* End of options. */
|
---|
1926 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
|
---|
1927 | return;
|
---|
1928 | case LWIP_TCP_OPT_NOP:
|
---|
1929 | /* NOP option. */
|
---|
1930 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
|
---|
1931 | break;
|
---|
1932 | case LWIP_TCP_OPT_MSS:
|
---|
1933 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
|
---|
1934 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_MSS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_MSS) > tcphdr_optlen) {
|
---|
1935 | /* Bad length */
|
---|
1936 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
1937 | return;
|
---|
1938 | }
|
---|
1939 | /* An MSS option with the right option length. */
|
---|
1940 | mss = (u16_t)(tcp_get_next_optbyte() << 8);
|
---|
1941 | mss |= tcp_get_next_optbyte();
|
---|
1942 | /* Limit the mss to the configured TCP_MSS and prevent division by zero */
|
---|
1943 | pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
|
---|
1944 | break;
|
---|
1945 | #if LWIP_WND_SCALE
|
---|
1946 | case LWIP_TCP_OPT_WS:
|
---|
1947 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: WND_SCALE\n"));
|
---|
1948 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_WS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_WS) > tcphdr_optlen) {
|
---|
1949 | /* Bad length */
|
---|
1950 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
1951 | return;
|
---|
1952 | }
|
---|
1953 | /* An WND_SCALE option with the right option length. */
|
---|
1954 | data = tcp_get_next_optbyte();
|
---|
1955 | /* If syn was received with wnd scale option,
|
---|
1956 | activate wnd scale opt, but only if this is not a retransmission */
|
---|
1957 | if ((flags & TCP_SYN) && !(pcb->flags & TF_WND_SCALE)) {
|
---|
1958 | pcb->snd_scale = data;
|
---|
1959 | if (pcb->snd_scale > 14U) {
|
---|
1960 | pcb->snd_scale = 14U;
|
---|
1961 | }
|
---|
1962 | pcb->rcv_scale = TCP_RCV_SCALE;
|
---|
1963 | tcp_set_flags(pcb, TF_WND_SCALE);
|
---|
1964 | /* window scaling is enabled, we can use the full receive window */
|
---|
1965 | LWIP_ASSERT("window not at default value", pcb->rcv_wnd == TCPWND_MIN16(TCP_WND));
|
---|
1966 | LWIP_ASSERT("window not at default value", pcb->rcv_ann_wnd == TCPWND_MIN16(TCP_WND));
|
---|
1967 | pcb->rcv_wnd = pcb->rcv_ann_wnd = TCP_WND;
|
---|
1968 | }
|
---|
1969 | break;
|
---|
1970 | #endif /* LWIP_WND_SCALE */
|
---|
1971 | #if LWIP_TCP_TIMESTAMPS
|
---|
1972 | case LWIP_TCP_OPT_TS:
|
---|
1973 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
|
---|
1974 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_TS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_TS) > tcphdr_optlen) {
|
---|
1975 | /* Bad length */
|
---|
1976 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
1977 | return;
|
---|
1978 | }
|
---|
1979 | /* TCP timestamp option with valid length */
|
---|
1980 | tsval = tcp_get_next_optbyte();
|
---|
1981 | tsval |= (tcp_get_next_optbyte() << 8);
|
---|
1982 | tsval |= (tcp_get_next_optbyte() << 16);
|
---|
1983 | tsval |= (tcp_get_next_optbyte() << 24);
|
---|
1984 | if (flags & TCP_SYN) {
|
---|
1985 | pcb->ts_recent = lwip_ntohl(tsval);
|
---|
1986 | /* Enable sending timestamps in every segment now that we know
|
---|
1987 | the remote host supports it. */
|
---|
1988 | tcp_set_flags(pcb, TF_TIMESTAMP);
|
---|
1989 | } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno + tcplen)) {
|
---|
1990 | pcb->ts_recent = lwip_ntohl(tsval);
|
---|
1991 | }
|
---|
1992 | /* Advance to next option (6 bytes already read) */
|
---|
1993 | tcp_optidx += LWIP_TCP_OPT_LEN_TS - 6;
|
---|
1994 | break;
|
---|
1995 | #endif /* LWIP_TCP_TIMESTAMPS */
|
---|
1996 | #if LWIP_TCP_SACK_OUT
|
---|
1997 | case LWIP_TCP_OPT_SACK_PERM:
|
---|
1998 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: SACK_PERM\n"));
|
---|
1999 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_SACK_PERM || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_SACK_PERM) > tcphdr_optlen) {
|
---|
2000 | /* Bad length */
|
---|
2001 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
2002 | return;
|
---|
2003 | }
|
---|
2004 | /* TCP SACK_PERM option with valid length */
|
---|
2005 | if (flags & TCP_SYN) {
|
---|
2006 | /* We only set it if we receive it in a SYN (or SYN+ACK) packet */
|
---|
2007 | tcp_set_flags(pcb, TF_SACK);
|
---|
2008 | }
|
---|
2009 | break;
|
---|
2010 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
2011 | default:
|
---|
2012 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
|
---|
2013 | data = tcp_get_next_optbyte();
|
---|
2014 | if (data < 2) {
|
---|
2015 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
2016 | /* If the length field is zero, the options are malformed
|
---|
2017 | and we don't process them further. */
|
---|
2018 | return;
|
---|
2019 | }
|
---|
2020 | /* All other options have a length field, so that we easily
|
---|
2021 | can skip past them. */
|
---|
2022 | tcp_optidx += data - 2;
|
---|
2023 | }
|
---|
2024 | }
|
---|
2025 | }
|
---|
2026 | }
|
---|
2027 |
|
---|
2028 | void
|
---|
2029 | tcp_trigger_input_pcb_close(void)
|
---|
2030 | {
|
---|
2031 | recv_flags |= TF_CLOSED;
|
---|
2032 | }
|
---|
2033 |
|
---|
2034 | #if LWIP_TCP_SACK_OUT
|
---|
2035 | /**
|
---|
2036 | * Called by tcp_receive() to add new SACK entry.
|
---|
2037 | *
|
---|
2038 | * The new SACK entry will be placed at the beginning of rcv_sacks[], as the newest one.
|
---|
2039 | * Existing SACK entries will be "pushed back", to preserve their order.
|
---|
2040 | * This is the behavior described in RFC 2018, section 4.
|
---|
2041 | *
|
---|
2042 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
2043 | * @param left the left side of the SACK (the first sequence number)
|
---|
2044 | * @param right the right side of the SACK (the first sequence number past this SACK)
|
---|
2045 | */
|
---|
2046 | static void
|
---|
2047 | tcp_add_sack(struct tcp_pcb *pcb, u32_t left, u32_t right)
|
---|
2048 | {
|
---|
2049 | u8_t i;
|
---|
2050 | u8_t unused_idx;
|
---|
2051 |
|
---|
2052 | if ((pcb->flags & TF_SACK) == 0 || !TCP_SEQ_LT(left, right)) {
|
---|
2053 | return;
|
---|
2054 | }
|
---|
2055 |
|
---|
2056 | /* First, let's remove all SACKs that are no longer needed (because they overlap with the newest one),
|
---|
2057 | while moving all other SACKs forward.
|
---|
2058 | We run this loop for all entries, until we find the first invalid one.
|
---|
2059 | There is no point checking after that. */
|
---|
2060 | for (i = unused_idx = 0; (i < LWIP_TCP_MAX_SACK_NUM) && LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
---|
2061 | /* We only want to use SACK at [i] if it doesn't overlap with left:right range.
|
---|
2062 | It does not overlap if its right side is before the newly added SACK,
|
---|
2063 | or if its left side is after the newly added SACK.
|
---|
2064 | NOTE: The equality should not really happen, but it doesn't hurt. */
|
---|
2065 | if (TCP_SEQ_LEQ(pcb->rcv_sacks[i].right, left) || TCP_SEQ_LEQ(right, pcb->rcv_sacks[i].left)) {
|
---|
2066 | if (unused_idx != i) {
|
---|
2067 | /* We don't need to copy if it's already in the right spot */
|
---|
2068 | pcb->rcv_sacks[unused_idx] = pcb->rcv_sacks[i];
|
---|
2069 | }
|
---|
2070 | ++unused_idx;
|
---|
2071 | }
|
---|
2072 | }
|
---|
2073 |
|
---|
2074 | /* Now 'unused_idx' is the index of the first invalid SACK entry,
|
---|
2075 | anywhere between 0 (no valid entries) and LWIP_TCP_MAX_SACK_NUM (all entries are valid).
|
---|
2076 | We want to clear this and all following SACKs.
|
---|
2077 | However, we will be adding another one in the front (and shifting everything else back).
|
---|
2078 | So let's just iterate from the back, and set each entry to the one to the left if it's valid,
|
---|
2079 | or to 0 if it is not. */
|
---|
2080 | for (i = LWIP_TCP_MAX_SACK_NUM - 1; i > 0; --i) {
|
---|
2081 | /* [i] is the index we are setting, and the value should be at index [i-1],
|
---|
2082 | or 0 if that index is unused (>= unused_idx). */
|
---|
2083 | if (i - 1 >= unused_idx) {
|
---|
2084 | /* [i-1] is unused. Let's clear [i]. */
|
---|
2085 | pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
|
---|
2086 | } else {
|
---|
2087 | pcb->rcv_sacks[i] = pcb->rcv_sacks[i - 1];
|
---|
2088 | }
|
---|
2089 | }
|
---|
2090 |
|
---|
2091 | /* And now we can store the newest SACK */
|
---|
2092 | pcb->rcv_sacks[0].left = left;
|
---|
2093 | pcb->rcv_sacks[0].right = right;
|
---|
2094 | }
|
---|
2095 |
|
---|
2096 | /**
|
---|
2097 | * Called to remove a range of SACKs.
|
---|
2098 | *
|
---|
2099 | * SACK entries will be removed or adjusted to not acknowledge any sequence
|
---|
2100 | * numbers that are less than 'seq' passed. It not only invalidates entries,
|
---|
2101 | * but also moves all entries that are still valid to the beginning.
|
---|
2102 | *
|
---|
2103 | * @param pcb the tcp_pcb to modify
|
---|
2104 | * @param seq the lowest sequence number to keep in SACK entries
|
---|
2105 | */
|
---|
2106 | static void
|
---|
2107 | tcp_remove_sacks_lt(struct tcp_pcb *pcb, u32_t seq)
|
---|
2108 | {
|
---|
2109 | u8_t i;
|
---|
2110 | u8_t unused_idx;
|
---|
2111 |
|
---|
2112 | /* We run this loop for all entries, until we find the first invalid one.
|
---|
2113 | There is no point checking after that. */
|
---|
2114 | for (i = unused_idx = 0; (i < LWIP_TCP_MAX_SACK_NUM) && LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
---|
2115 | /* We only want to use SACK at index [i] if its right side is > 'seq'. */
|
---|
2116 | if (TCP_SEQ_GT(pcb->rcv_sacks[i].right, seq)) {
|
---|
2117 | if (unused_idx != i) {
|
---|
2118 | /* We only copy it if it's not in the right spot already. */
|
---|
2119 | pcb->rcv_sacks[unused_idx] = pcb->rcv_sacks[i];
|
---|
2120 | }
|
---|
2121 | /* NOTE: It is possible that its left side is < 'seq', in which case we should adjust it. */
|
---|
2122 | if (TCP_SEQ_LT(pcb->rcv_sacks[unused_idx].left, seq)) {
|
---|
2123 | pcb->rcv_sacks[unused_idx].left = seq;
|
---|
2124 | }
|
---|
2125 | ++unused_idx;
|
---|
2126 | }
|
---|
2127 | }
|
---|
2128 |
|
---|
2129 | /* We also need to invalidate everything from 'unused_idx' till the end */
|
---|
2130 | for (i = unused_idx; i < LWIP_TCP_MAX_SACK_NUM; ++i) {
|
---|
2131 | pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
|
---|
2132 | }
|
---|
2133 | }
|
---|
2134 |
|
---|
2135 | #if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
|
---|
2136 | /**
|
---|
2137 | * Called to remove a range of SACKs.
|
---|
2138 | *
|
---|
2139 | * SACK entries will be removed or adjusted to not acknowledge any sequence
|
---|
2140 | * numbers that are greater than (or equal to) 'seq' passed. It not only invalidates entries,
|
---|
2141 | * but also moves all entries that are still valid to the beginning.
|
---|
2142 | *
|
---|
2143 | * @param pcb the tcp_pcb to modify
|
---|
2144 | * @param seq the highest sequence number to keep in SACK entries
|
---|
2145 | */
|
---|
2146 | static void
|
---|
2147 | tcp_remove_sacks_gt(struct tcp_pcb *pcb, u32_t seq)
|
---|
2148 | {
|
---|
2149 | u8_t i;
|
---|
2150 | u8_t unused_idx;
|
---|
2151 |
|
---|
2152 | /* We run this loop for all entries, until we find the first invalid one.
|
---|
2153 | There is no point checking after that. */
|
---|
2154 | for (i = unused_idx = 0; (i < LWIP_TCP_MAX_SACK_NUM) && LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
---|
2155 | /* We only want to use SACK at index [i] if its left side is < 'seq'. */
|
---|
2156 | if (TCP_SEQ_LT(pcb->rcv_sacks[i].left, seq)) {
|
---|
2157 | if (unused_idx != i) {
|
---|
2158 | /* We only copy it if it's not in the right spot already. */
|
---|
2159 | pcb->rcv_sacks[unused_idx] = pcb->rcv_sacks[i];
|
---|
2160 | }
|
---|
2161 | /* NOTE: It is possible that its right side is > 'seq', in which case we should adjust it. */
|
---|
2162 | if (TCP_SEQ_GT(pcb->rcv_sacks[unused_idx].right, seq)) {
|
---|
2163 | pcb->rcv_sacks[unused_idx].right = seq;
|
---|
2164 | }
|
---|
2165 | ++unused_idx;
|
---|
2166 | }
|
---|
2167 | }
|
---|
2168 |
|
---|
2169 | /* We also need to invalidate everything from 'unused_idx' till the end */
|
---|
2170 | for (i = unused_idx; i < LWIP_TCP_MAX_SACK_NUM; ++i) {
|
---|
2171 | pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
|
---|
2172 | }
|
---|
2173 | }
|
---|
2174 | #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
|
---|
2175 |
|
---|
2176 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
2177 |
|
---|
2178 | #endif /* LWIP_TCP */
|
---|