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1 /* |
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2 * Copyright (c) 1982, 1986, 1988, 1993 |
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3 * The Regents of the University of California. 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. All advertising materials mentioning features or use of this software |
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14 * must display the following acknowledgement: |
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15 * This product includes software developed by the University of |
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16 * California, Berkeley and its contributors. |
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17 * 4. Neither the name of the University nor the names of its contributors |
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18 * may be used to endorse or promote products derived from this software |
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19 * without specific prior written permission. |
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20 * |
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21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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31 * SUCH DAMAGE. |
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32 * |
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33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 |
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34 * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp |
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35 */ |
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36 |
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37 #include "slirp.h" |
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38 #include "ip_icmp.h" |
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39 |
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40 #ifdef LOG_ENABLED |
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41 struct icmpstat icmpstat; |
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42 #endif |
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43 |
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44 /* The message sent when emulating PING */ |
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45 /* Be nice and tell them it's just a pseudo-ping packet */ |
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46 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n"; |
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47 |
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48 /* list of actions for icmp_error() on RX of an icmp message */ |
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49 static const int icmp_flush[19] = { |
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50 /* ECHO REPLY (0) */ 0, |
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51 1, |
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52 1, |
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53 /* DEST UNREACH (3) */ 1, |
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54 /* SOURCE QUENCH (4)*/ 1, |
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55 /* REDIRECT (5) */ 1, |
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56 1, |
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57 1, |
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58 /* ECHO (8) */ 0, |
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59 /* ROUTERADVERT (9) */ 1, |
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60 /* ROUTERSOLICIT (10) */ 1, |
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61 /* TIME EXCEEDED (11) */ 1, |
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62 /* PARAMETER PROBLEM (12) */ 1, |
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63 /* TIMESTAMP (13) */ 0, |
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64 /* TIMESTAMP REPLY (14) */ 0, |
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65 /* INFO (15) */ 0, |
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66 /* INFO REPLY (16) */ 0, |
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67 /* ADDR MASK (17) */ 0, |
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68 /* ADDR MASK REPLY (18) */ 0 |
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69 }; |
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70 |
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71 /* |
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72 * Process a received ICMP message. |
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73 */ |
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74 void |
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75 icmp_input(m, hlen) |
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76 struct mbuf *m; |
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77 int hlen; |
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78 { |
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79 register struct icmp *icp; |
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80 register struct ip *ip=mtod(m, struct ip *); |
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81 int icmplen=ip->ip_len; |
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82 /* int code; */ |
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83 |
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84 DEBUG_CALL("icmp_input"); |
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85 DEBUG_ARG("m = %lx", (long )m); |
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86 DEBUG_ARG("m_len = %d", m->m_len); |
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87 |
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88 STAT(icmpstat.icps_received++); |
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89 |
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90 /* |
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91 * Locate icmp structure in mbuf, and check |
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92 * that its not corrupted and of at least minimum length. |
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93 */ |
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94 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */ |
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95 STAT(icmpstat.icps_tooshort++); |
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96 freeit: |
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97 m_freem(m); |
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98 goto end_error; |
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99 } |
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100 |
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101 m->m_len -= hlen; |
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102 m->m_data += hlen; |
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103 icp = mtod(m, struct icmp *); |
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104 if (cksum(m, icmplen)) { |
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105 STAT(icmpstat.icps_checksum++); |
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106 goto freeit; |
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107 } |
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108 m->m_len += hlen; |
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109 m->m_data -= hlen; |
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110 |
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111 /* icmpstat.icps_inhist[icp->icmp_type]++; */ |
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112 /* code = icp->icmp_code; */ |
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113 |
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114 DEBUG_ARG("icmp_type = %d", icp->icmp_type); |
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115 switch (icp->icmp_type) { |
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116 case ICMP_ECHO: |
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117 icp->icmp_type = ICMP_ECHOREPLY; |
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118 ip->ip_len += hlen; /* since ip_input subtracts this */ |
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119 if (ip->ip_dst.s_addr == alias_addr.s_addr) { |
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120 icmp_reflect(m); |
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121 } else { |
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122 struct socket *so; |
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123 struct sockaddr_in addr; |
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124 if ((so = socreate()) == NULL) goto freeit; |
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125 if(udp_attach(so) == -1) { |
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126 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n", |
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127 errno,strerror(errno))); |
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128 sofree(so); |
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129 m_free(m); |
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130 goto end_error; |
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131 } |
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132 so->so_m = m; |
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133 so->so_faddr = ip->ip_dst; |
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134 so->so_fport = htons(7); |
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135 so->so_laddr = ip->ip_src; |
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136 so->so_lport = htons(9); |
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137 so->so_iptos = ip->ip_tos; |
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138 so->so_type = IPPROTO_ICMP; |
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139 so->so_state = SS_ISFCONNECTED; |
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140 |
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141 /* Send the packet */ |
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142 addr.sin_family = AF_INET; |
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143 if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) { |
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144 /* It's an alias */ |
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145 switch(ntohl(so->so_faddr.s_addr) & 0xff) { |
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146 case CTL_DNS: |
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147 addr.sin_addr = dns_addr; |
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148 break; |
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149 case CTL_ALIAS: |
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150 default: |
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151 addr.sin_addr = loopback_addr; |
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152 break; |
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153 } |
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154 } else { |
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155 addr.sin_addr = so->so_faddr; |
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156 } |
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157 addr.sin_port = so->so_fport; |
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158 if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0, |
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159 (struct sockaddr *)&addr, sizeof(addr)) == -1) { |
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160 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n", |
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161 errno,strerror(errno))); |
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162 icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno)); |
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163 udp_detach(so); |
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164 } |
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165 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */ |
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166 break; |
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167 case ICMP_UNREACH: |
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168 /* XXX? report error? close socket? */ |
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169 case ICMP_TIMXCEED: |
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170 case ICMP_PARAMPROB: |
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171 case ICMP_SOURCEQUENCH: |
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172 case ICMP_TSTAMP: |
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173 case ICMP_MASKREQ: |
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174 case ICMP_REDIRECT: |
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175 STAT(icmpstat.icps_notsupp++); |
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176 m_freem(m); |
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177 break; |
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178 |
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179 default: |
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180 STAT(icmpstat.icps_badtype++); |
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181 m_freem(m); |
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182 } /* swith */ |
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183 |
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184 end_error: |
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185 /* m is m_free()'d xor put in a socket xor or given to ip_send */ |
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186 return; |
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187 } |
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188 |
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189 |
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190 /* |
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191 * Send an ICMP message in response to a situation |
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192 * |
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193 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do). |
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194 * MUST NOT change this header information. |
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195 * MUST NOT reply to a multicast/broadcast IP address. |
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196 * MUST NOT reply to a multicast/broadcast MAC address. |
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197 * MUST reply to only the first fragment. |
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198 */ |
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199 /* |
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200 * Send ICMP_UNREACH back to the source regarding msrc. |
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201 * mbuf *msrc is used as a template, but is NOT m_free()'d. |
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202 * It is reported as the bad ip packet. The header should |
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203 * be fully correct and in host byte order. |
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204 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one |
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205 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548 |
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206 */ |
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207 |
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208 #define ICMP_MAXDATALEN (IP_MSS-28) |
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209 void |
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210 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize, |
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211 const char *message) |
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212 { |
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213 unsigned hlen, shlen, s_ip_len; |
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214 register struct ip *ip; |
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215 register struct icmp *icp; |
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216 register struct mbuf *m; |
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217 |
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218 DEBUG_CALL("icmp_error"); |
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219 DEBUG_ARG("msrc = %lx", (long )msrc); |
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220 DEBUG_ARG("msrc_len = %d", msrc->m_len); |
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221 |
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222 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error; |
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223 |
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224 /* check msrc */ |
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225 if(!msrc) goto end_error; |
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226 ip = mtod(msrc, struct ip *); |
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227 #ifdef DEBUG |
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228 { char bufa[20], bufb[20]; |
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229 strcpy(bufa, inet_ntoa(ip->ip_src)); |
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230 strcpy(bufb, inet_ntoa(ip->ip_dst)); |
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231 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb)); |
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232 } |
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233 #endif |
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234 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */ |
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235 |
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236 shlen=ip->ip_hl << 2; |
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237 s_ip_len=ip->ip_len; |
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238 if(ip->ip_p == IPPROTO_ICMP) { |
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239 icp = (struct icmp *)((char *)ip + shlen); |
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240 /* |
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241 * Assume any unknown ICMP type is an error. This isn't |
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242 * specified by the RFC, but think about it.. |
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243 */ |
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244 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error; |
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245 } |
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246 |
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247 /* make a copy */ |
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248 if(!(m=m_get())) goto end_error; /* get mbuf */ |
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249 { int new_m_size; |
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250 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN; |
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251 if(new_m_size>m->m_size) m_inc(m, new_m_size); |
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252 } |
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253 memcpy(m->m_data, msrc->m_data, msrc->m_len); |
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254 m->m_len = msrc->m_len; /* copy msrc to m */ |
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255 |
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256 /* make the header of the reply packet */ |
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257 ip = mtod(m, struct ip *); |
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258 hlen= sizeof(struct ip ); /* no options in reply */ |
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259 |
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260 /* fill in icmp */ |
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261 m->m_data += hlen; |
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262 m->m_len -= hlen; |
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263 |
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264 icp = mtod(m, struct icmp *); |
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265 |
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266 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */ |
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267 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */ |
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268 s_ip_len=ICMP_MAXDATALEN; |
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269 |
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270 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */ |
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271 |
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272 /* min. size = 8+sizeof(struct ip)+8 */ |
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273 |
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274 icp->icmp_type = type; |
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275 icp->icmp_code = code; |
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276 icp->icmp_id = 0; |
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277 icp->icmp_seq = 0; |
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278 |
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279 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */ |
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280 HTONS(icp->icmp_ip.ip_len); |
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281 HTONS(icp->icmp_ip.ip_id); |
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282 HTONS(icp->icmp_ip.ip_off); |
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283 |
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284 #ifdef DEBUG |
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285 if(message) { /* DEBUG : append message to ICMP packet */ |
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286 int message_len; |
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287 char *cpnt; |
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288 message_len=strlen(message); |
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289 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN; |
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290 cpnt=(char *)m->m_data+m->m_len; |
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291 memcpy(cpnt, message, message_len); |
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292 m->m_len+=message_len; |
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293 } |
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294 #endif |
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295 |
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296 icp->icmp_cksum = 0; |
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297 icp->icmp_cksum = cksum(m, m->m_len); |
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298 |
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299 m->m_data -= hlen; |
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300 m->m_len += hlen; |
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301 |
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302 /* fill in ip */ |
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303 ip->ip_hl = hlen >> 2; |
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304 ip->ip_len = m->m_len; |
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305 |
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306 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */ |
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307 |
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308 ip->ip_ttl = MAXTTL; |
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309 ip->ip_p = IPPROTO_ICMP; |
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310 ip->ip_dst = ip->ip_src; /* ip adresses */ |
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311 ip->ip_src = alias_addr; |
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312 |
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313 (void ) ip_output((struct socket *)NULL, m); |
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314 |
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315 STAT(icmpstat.icps_reflect++); |
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316 |
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317 end_error: |
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318 return; |
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319 } |
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320 #undef ICMP_MAXDATALEN |
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321 |
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322 /* |
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323 * Reflect the ip packet back to the source |
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324 */ |
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325 void |
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326 icmp_reflect(m) |
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327 struct mbuf *m; |
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328 { |
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329 register struct ip *ip = mtod(m, struct ip *); |
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330 int hlen = ip->ip_hl << 2; |
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331 int optlen = hlen - sizeof(struct ip ); |
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332 register struct icmp *icp; |
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333 |
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334 /* |
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335 * Send an icmp packet back to the ip level, |
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336 * after supplying a checksum. |
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337 */ |
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338 m->m_data += hlen; |
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339 m->m_len -= hlen; |
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340 icp = mtod(m, struct icmp *); |
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341 |
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342 icp->icmp_cksum = 0; |
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343 icp->icmp_cksum = cksum(m, ip->ip_len - hlen); |
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344 |
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345 m->m_data -= hlen; |
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346 m->m_len += hlen; |
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347 |
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348 /* fill in ip */ |
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349 if (optlen > 0) { |
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350 /* |
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351 * Strip out original options by copying rest of first |
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352 * mbuf's data back, and adjust the IP length. |
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353 */ |
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354 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen, |
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355 (unsigned )(m->m_len - hlen)); |
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356 hlen -= optlen; |
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357 ip->ip_hl = hlen >> 2; |
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358 ip->ip_len -= optlen; |
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359 m->m_len -= optlen; |
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360 } |
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361 |
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362 ip->ip_ttl = MAXTTL; |
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363 { /* swap */ |
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364 struct in_addr icmp_dst; |
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365 icmp_dst = ip->ip_dst; |
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366 ip->ip_dst = ip->ip_src; |
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367 ip->ip_src = icmp_dst; |
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368 } |
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369 |
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370 (void ) ip_output((struct socket *)NULL, m); |
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371 |
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372 STAT(icmpstat.icps_reflect++); |
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373 } |