1 | /*
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2 | * Copyright (c) 2004, Swedish Institute of Computer Science.
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3 | * All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the Institute nor the names of its contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | *
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29 | * This file is part of the uIP TCP/IP stack
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30 | *
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31 | * Author: Adam Dunkels <adam@sics.se>
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32 | *
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33 | * $Id: uip-fw.c 158 2016-02-20 13:43:32Z coas-nagasima $
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34 | */
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35 | /**
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36 | * \addtogroup uip
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37 | * @{
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38 | */
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39 |
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40 | /**
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41 | * \defgroup uipfw uIP packet forwarding
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42 | * @{
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43 | *
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44 | */
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45 |
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46 | /**
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47 | * \file
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48 | * uIP packet forwarding.
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49 | * \author Adam Dunkels <adam@sics.se>
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50 | *
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51 | * This file implements a number of simple functions which do packet
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52 | * forwarding over multiple network interfaces with uIP.
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53 | *
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54 | */
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55 |
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56 | #include "net/ip/uip.h"
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57 | #include "net/ip/uip_arch.h"
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58 | #include "net/ipv4/uip-fw.h"
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59 |
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60 | #include <string.h> /* for memcpy() */
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61 |
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62 | #ifdef __RX
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63 | #pragma pack
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64 | #elif _MSC_VER
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65 | #pragma pack(push, 1)
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66 | #endif
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67 |
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68 | /*
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69 | * The list of registered network interfaces.
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70 | */
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71 | static struct uip_fw_netif *netifs = NULL;
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72 |
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73 | /*
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74 | * A pointer to the default network interface.
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75 | */
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76 | static struct uip_fw_netif *defaultnetif = NULL;
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77 |
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78 | struct tcpip_hdr {
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79 | /* IP header. */
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80 | uint8_t vhl,
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81 | tos;
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82 | uint16_t len,
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83 | ipid,
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84 | ipoffset;
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85 | uint8_t ttl,
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86 | proto;
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87 | uint16_t ipchksum;
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88 | uint16_t srcipaddr[2],
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89 | destipaddr[2];
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90 |
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91 | /* TCP header. */
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92 | uint16_t srcport,
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93 | destport;
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94 | uint8_t seqno[4],
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95 | ackno[4],
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96 | tcpoffset,
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97 | flags,
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98 | wnd[2];
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99 | uint16_t tcpchksum;
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100 | uint8_t urgp[2];
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101 | uint8_t optdata[4];
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102 | };
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103 |
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104 | struct icmpip_hdr {
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105 | /* IP header. */
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106 | uint8_t vhl,
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107 | tos,
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108 | len[2],
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109 | ipid[2],
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110 | ipoffset[2],
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111 | ttl,
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112 | proto;
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113 | uint16_t ipchksum;
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114 | uint16_t srcipaddr[2],
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115 | destipaddr[2];
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116 | /* ICMP (echo) header. */
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117 | uint8_t type, icode;
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118 | uint16_t icmpchksum;
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119 | uint16_t id, seqno;
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120 | uint8_t payload[1];
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121 | };
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122 |
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123 | /* ICMP ECHO. */
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124 | #define ICMP_ECHO 8
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125 |
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126 | /* ICMP TIME-EXCEEDED. */
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127 | #define ICMP_TE 11
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128 |
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129 | /*
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130 | * Pointer to the TCP/IP headers of the packet in the uip_buf buffer.
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131 | */
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132 | #define BUF ((struct tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
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133 |
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134 | /*
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135 | * Pointer to the ICMP/IP headers of the packet in the uip_buf buffer.
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136 | */
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137 | #define ICMPBUF ((struct icmpip_hdr *)&uip_buf[UIP_LLH_LEN])
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138 |
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139 | /*
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140 | * Certain fields of an IP packet that are used for identifying
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141 | * duplicate packets.
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142 | */
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143 | struct fwcache_entry {
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144 | uint16_t timer;
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145 |
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146 | uint16_t srcipaddr[2];
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147 | uint16_t destipaddr[2];
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148 | uint16_t ipid;
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149 | uint8_t proto;
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150 | uint8_t unused;
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151 |
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152 | #if notdef
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153 | uint16_t payload[2];
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154 | #endif
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155 |
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156 | #if UIP_REASSEMBLY > 0
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157 | uint16_t len, offset;
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158 | #endif
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159 | };
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160 |
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161 | #ifdef __RX
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162 | #pragma unpack
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163 | #elif _MSC_VER
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164 | #pragma pack(pop)
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165 | #endif
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166 |
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167 | /*
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168 | * The number of packets to remember when looking for duplicates.
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169 | */
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170 | #ifdef UIP_CONF_FWCACHE_SIZE
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171 | #define FWCACHE_SIZE UIP_CONF_FWCACHE_SIZE
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172 | #else
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173 | #define FWCACHE_SIZE 2
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174 | #endif
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175 |
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176 |
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177 | /*
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178 | * A cache of packet header fields which are used for
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179 | * identifying duplicate packets.
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180 | */
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181 | static struct fwcache_entry fwcache[FWCACHE_SIZE];
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182 |
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183 | /**
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184 | * \internal
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185 | * The time that a packet cache is active.
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186 | */
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187 | #define FW_TIME 20
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188 |
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189 | /*------------------------------------------------------------------------------*/
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190 | /**
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191 | * Initialize the uIP packet forwarding module.
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192 | */
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193 | /*------------------------------------------------------------------------------*/
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194 | void
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195 | uip_fw_init(void)
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196 | {
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197 | struct uip_fw_netif *t;
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198 | defaultnetif = NULL;
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199 | while(netifs != NULL) {
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200 | t = netifs;
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201 | netifs = netifs->next;
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202 | t->next = NULL;
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203 | }
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204 | }
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205 | /*------------------------------------------------------------------------------*/
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206 | /**
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207 | * \internal
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208 | * Check if an IP address is within the network defined by an IP
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209 | * address and a netmask.
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210 | *
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211 | * \param ipaddr The IP address to be checked.
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212 | * \param netipaddr The IP address of the network.
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213 | * \param netmask The netmask of the network.
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214 | *
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215 | * \return Non-zero if IP address is in network, zero otherwise.
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216 | */
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217 | /*------------------------------------------------------------------------------*/
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218 | static unsigned char
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219 | ipaddr_maskcmp(uint16_t *ipaddr, uint16_t *netipaddr, uint16_t *netmask)
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220 | {
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221 | return (ipaddr[0] & netmask [0]) == (netipaddr[0] & netmask[0]) &&
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222 | (ipaddr[1] & netmask[1]) == (netipaddr[1] & netmask[1]);
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223 | }
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224 | /*------------------------------------------------------------------------------*/
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225 | /**
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226 | * \internal
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227 | * Send out an ICMP TIME-EXCEEDED message.
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228 | *
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229 | * This function replaces the packet in the uip_buf buffer with the
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230 | * ICMP packet.
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231 | */
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232 | /*------------------------------------------------------------------------------*/
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233 | static void
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234 | time_exceeded(void)
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235 | {
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236 | uint16_t tmp16;
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237 |
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238 | /* We don't send out ICMP errors for ICMP messages. */
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239 | if(ICMPBUF->proto == UIP_PROTO_ICMP) {
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240 | uip_len = 0;
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241 | return;
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242 | }
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243 | /* Copy fields from packet header into payload of this ICMP packet. */
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244 | memcpy(&(ICMPBUF->payload[0]), ICMPBUF, 28);
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245 |
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246 | /* Set the ICMP type and code. */
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247 | ICMPBUF->type = ICMP_TE;
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248 | ICMPBUF->icode = 0;
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249 |
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250 | /* Calculate the ICMP checksum. */
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251 | ICMPBUF->icmpchksum = 0;
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252 | ICMPBUF->icmpchksum = ~uip_chksum((uint16_t *)&(ICMPBUF->type), 36);
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253 |
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254 | /* Set the IP destination address to be the source address of the
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255 | original packet. */
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256 | tmp16= BUF->destipaddr[0];
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257 | BUF->destipaddr[0] = BUF->srcipaddr[0];
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258 | BUF->srcipaddr[0] = tmp16;
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259 | tmp16 = BUF->destipaddr[1];
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260 | BUF->destipaddr[1] = BUF->srcipaddr[1];
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261 | BUF->srcipaddr[1] = tmp16;
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262 |
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263 | /* Set our IP address as the source address. */
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264 | BUF->srcipaddr[0] = uip_hostaddr[0];
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265 | BUF->srcipaddr[1] = uip_hostaddr[1];
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266 |
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267 | /* The size of the ICMP time exceeded packet is 36 + the size of the
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268 | IP header (20) = 56. */
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269 | uip_len = 56;
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270 | ICMPBUF->len[0] = 0;
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271 | ICMPBUF->len[1] = uip_len;
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272 |
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273 | /* Fill in the other fields in the IP header. */
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274 | ICMPBUF->vhl = 0x45;
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275 | ICMPBUF->tos = 0;
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276 | ICMPBUF->ipoffset[0] = ICMPBUF->ipoffset[1] = 0;
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277 | ICMPBUF->ttl = UIP_TTL;
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278 | ICMPBUF->proto = UIP_PROTO_ICMP;
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279 |
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280 | /* Calculate IP checksum. */
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281 | ICMPBUF->ipchksum = 0;
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282 | ICMPBUF->ipchksum = ~(uip_ipchksum());
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283 |
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284 |
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285 | }
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286 | /*------------------------------------------------------------------------------*/
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287 | /**
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288 | * \internal
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289 | * Register a packet in the forwarding cache so that it won't be
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290 | * forwarded again.
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291 | */
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292 | /*------------------------------------------------------------------------------*/
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293 | static void
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294 | fwcache_register(void)
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295 | {
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296 | struct fwcache_entry *fw;
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297 | int i, oldest;
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298 |
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299 | oldest = FW_TIME;
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300 | fw = NULL;
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301 |
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302 | /* Find the oldest entry in the cache. */
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303 | for(i = 0; i < FWCACHE_SIZE; ++i) {
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304 | if(fwcache[i].timer == 0) {
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305 | fw = &fwcache[i];
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306 | break;
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307 | } else if(fwcache[i].timer <= oldest) {
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308 | fw = &fwcache[i];
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309 | oldest = fwcache[i].timer;
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310 | }
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311 | }
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312 |
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313 | fw->timer = FW_TIME;
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314 | fw->ipid = BUF->ipid;
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315 | fw->srcipaddr[0] = BUF->srcipaddr[0];
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316 | fw->srcipaddr[1] = BUF->srcipaddr[1];
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317 | fw->destipaddr[0] = BUF->destipaddr[0];
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318 | fw->destipaddr[1] = BUF->destipaddr[1];
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319 | fw->proto = BUF->proto;
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320 | #if notdef
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321 | fw->payload[0] = BUF->srcport;
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322 | fw->payload[1] = BUF->destport;
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323 | #endif
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324 | #if UIP_REASSEMBLY > 0
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325 | fw->len = BUF->len;
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326 | fw->offset = BUF->ipoffset;
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327 | #endif
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328 | }
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329 | /*------------------------------------------------------------------------------*/
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330 | /**
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331 | * \internal
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332 | * Find a network interface for the IP packet in uip_buf.
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333 | */
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334 | /*------------------------------------------------------------------------------*/
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335 | static struct uip_fw_netif *
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336 | find_netif(void)
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337 | {
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338 | struct uip_fw_netif *netif;
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339 |
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340 | /* Walk through every network interface to check for a match. */
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341 | for(netif = netifs; netif != NULL; netif = netif->next) {
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342 | if(ipaddr_maskcmp(BUF->destipaddr, netif->ipaddr,
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343 | netif->netmask)) {
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344 | /* If there was a match, we break the loop. */
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345 | return netif;
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346 | }
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347 | }
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348 |
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349 | /* If no matching netif was found, we use default netif. */
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350 | return defaultnetif;
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351 | }
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352 | /*------------------------------------------------------------------------------*/
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353 | /**
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354 | * Output an IP packet on the correct network interface.
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355 | *
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356 | * The IP packet should be present in the uip_buf buffer and its
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357 | * length in the global uip_len variable.
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358 | *
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359 | * \retval UIP_FW_ZEROLEN Indicates that a zero-length packet
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360 | * transmission was attempted and that no packet was sent.
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361 | *
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362 | * \retval UIP_FW_NOROUTE No suitable network interface could be found
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363 | * for the outbound packet, and the packet was not sent.
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364 | *
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365 | * \return The return value from the actual network interface output
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366 | * function is passed unmodified as a return value.
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367 | */
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368 | /*------------------------------------------------------------------------------*/
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369 | uint8_t
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370 | uip_fw_output(void)
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371 | {
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372 | struct uip_fw_netif *netif;
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373 |
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374 | if(uip_len == 0) {
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375 | return UIP_FW_ZEROLEN;
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376 | }
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377 |
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378 | fwcache_register();
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379 |
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380 | #if UIP_BROADCAST
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381 | /* Link local broadcasts go out on all interfaces. */
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382 | if(/*BUF->proto == UIP_PROTO_UDP &&*/
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383 | BUF->destipaddr[0] == 0xffff &&
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384 | BUF->destipaddr[1] == 0xffff) {
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385 | if(defaultnetif != NULL) {
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386 | defaultnetif->output();
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387 | }
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388 | for(netif = netifs; netif != NULL; netif = netif->next) {
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389 | netif->output();
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390 | }
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391 | return UIP_FW_OK;
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392 | }
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393 | #endif /* UIP_BROADCAST */
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394 |
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395 | netif = find_netif();
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396 | /* printf("uip_fw_output: netif %p ->output %p len %d\n", netif,
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397 | netif->output,
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398 | uip_len);*/
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399 |
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400 | if(netif == NULL) {
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401 | return UIP_FW_NOROUTE;
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402 | }
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403 | /* If we now have found a suitable network interface, we call its
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404 | output function to send out the packet. */
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405 | return netif->output();
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406 | }
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407 | /*------------------------------------------------------------------------------*/
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408 | /**
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409 | * Forward an IP packet in the uip_buf buffer.
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410 | *
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411 | *
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412 | *
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413 | * \return UIP_FW_FORWARDED if the packet was forwarded, UIP_FW_LOCAL if
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414 | * the packet should be processed locally.
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415 | */
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416 | /*------------------------------------------------------------------------------*/
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417 | uint8_t
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418 | uip_fw_forward(void)
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419 | {
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420 | struct fwcache_entry *fw;
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421 |
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422 | /* First check if the packet is destined for ourselves and return 0
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423 | to indicate that the packet should be processed locally. */
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424 | if(BUF->destipaddr[0] == uip_hostaddr[0] &&
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425 | BUF->destipaddr[1] == uip_hostaddr[1]) {
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426 | return UIP_FW_LOCAL;
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427 | }
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428 |
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429 | /* If we use ping IP address configuration, and our IP address is
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430 | not yet configured, we should intercept all ICMP echo packets. */
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431 | #if UIP_PINGADDRCONF
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432 | if((uip_hostaddr[0] | uip_hostaddr[1]) == 0 &&
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433 | BUF->proto == UIP_PROTO_ICMP &&
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434 | ICMPBUF->type == ICMP_ECHO) {
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435 | return UIP_FW_LOCAL;
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436 | }
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437 | #endif /* UIP_PINGADDRCONF */
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438 |
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439 | /* Check if the packet is in the forwarding cache already, and if so
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440 | we drop it. */
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441 |
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442 | for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
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443 | if(fw->timer != 0 &&
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444 | #if UIP_REASSEMBLY > 0
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445 | fw->len == BUF->len &&
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446 | fw->offset == BUF->ipoffset &&
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447 | #endif
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448 | fw->ipid == BUF->ipid &&
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449 | fw->srcipaddr[0] == BUF->srcipaddr[0] &&
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450 | fw->srcipaddr[1] == BUF->srcipaddr[1] &&
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451 | fw->destipaddr[0] == BUF->destipaddr[0] &&
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452 | fw->destipaddr[1] == BUF->destipaddr[1] &&
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453 | #if notdef
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454 | fw->payload[0] == BUF->srcport &&
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455 | fw->payload[1] == BUF->destport &&
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456 | #endif
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457 | fw->proto == BUF->proto) {
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458 | /* Drop packet. */
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459 | return UIP_FW_FORWARDED;
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460 | }
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461 | }
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462 |
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463 | /* If the TTL reaches zero we produce an ICMP time exceeded message
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464 | in the uip_buf buffer and forward that packet back to the sender
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465 | of the packet. */
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466 | if(BUF->ttl <= 1) {
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467 | /* No time exceeded for broadcasts and multicasts! */
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468 | if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
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469 | return UIP_FW_LOCAL;
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470 | }
|
---|
471 | time_exceeded();
|
---|
472 | }
|
---|
473 |
|
---|
474 | /* Decrement the TTL (time-to-live) value in the IP header */
|
---|
475 | BUF->ttl = BUF->ttl - 1;
|
---|
476 |
|
---|
477 | /* Update the IP checksum. */
|
---|
478 | if(BUF->ipchksum >= HTONS(0xffff - 0x0100)) {
|
---|
479 | BUF->ipchksum = BUF->ipchksum + HTONS(0x0100) + 1;
|
---|
480 | } else {
|
---|
481 | BUF->ipchksum = BUF->ipchksum + HTONS(0x0100);
|
---|
482 | }
|
---|
483 |
|
---|
484 | if(uip_len > 0) {
|
---|
485 | uip_appdata = &uip_buf[UIP_LLH_LEN + UIP_TCPIP_HLEN];
|
---|
486 | uip_fw_output();
|
---|
487 | }
|
---|
488 |
|
---|
489 | #if UIP_BROADCAST
|
---|
490 | if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
|
---|
491 | return UIP_FW_LOCAL;
|
---|
492 | }
|
---|
493 | #endif /* UIP_BROADCAST */
|
---|
494 |
|
---|
495 | /* Return non-zero to indicate that the packet was forwarded and that no
|
---|
496 | other processing should be made. */
|
---|
497 | return UIP_FW_FORWARDED;
|
---|
498 | }
|
---|
499 | /*------------------------------------------------------------------------------*/
|
---|
500 | /**
|
---|
501 | * Register a network interface with the forwarding module.
|
---|
502 | *
|
---|
503 | * \param netif A pointer to the network interface that is to be
|
---|
504 | * registered.
|
---|
505 | */
|
---|
506 | /*------------------------------------------------------------------------------*/
|
---|
507 | void
|
---|
508 | uip_fw_register(struct uip_fw_netif *netif)
|
---|
509 | {
|
---|
510 | netif->next = netifs;
|
---|
511 | netifs = netif;
|
---|
512 | }
|
---|
513 | /*------------------------------------------------------------------------------*/
|
---|
514 | /**
|
---|
515 | * Register a default network interface.
|
---|
516 | *
|
---|
517 | * All packets that don't go out on any of the other interfaces will
|
---|
518 | * be routed to the default interface.
|
---|
519 | *
|
---|
520 | * \param netif A pointer to the network interface that is to be
|
---|
521 | * registered.
|
---|
522 | */
|
---|
523 | /*------------------------------------------------------------------------------*/
|
---|
524 | void
|
---|
525 | uip_fw_default(struct uip_fw_netif *netif)
|
---|
526 | {
|
---|
527 | defaultnetif = netif;
|
---|
528 | }
|
---|
529 | /*------------------------------------------------------------------------------*/
|
---|
530 | /**
|
---|
531 | * Perform periodic processing.
|
---|
532 | */
|
---|
533 | /*------------------------------------------------------------------------------*/
|
---|
534 | void
|
---|
535 | uip_fw_periodic(void)
|
---|
536 | {
|
---|
537 | struct fwcache_entry *fw;
|
---|
538 | for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
|
---|
539 | if(fw->timer > 0) {
|
---|
540 | --fw->timer;
|
---|
541 | }
|
---|
542 | }
|
---|
543 | }
|
---|
544 | /*------------------------------------------------------------------------------*/
|
---|