1 /* 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 30 * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp 31 */ 32 33 #include "slirp.h" 34 #include "ip_icmp.h" 35 36 #ifdef LOG_ENABLED 37 struct icmpstat icmpstat; 38 #endif 39 40 /* The message sent when emulating PING */ 41 /* Be nice and tell them it's just a pseudo-ping packet */ 42 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n"; 43 44 /* list of actions for icmp_error() on RX of an icmp message */ 45 static const int icmp_flush[19] = { 46 /* ECHO REPLY (0) */ 0, 47 1, 48 1, 49 /* DEST UNREACH (3) */ 1, 50 /* SOURCE QUENCH (4)*/ 1, 51 /* REDIRECT (5) */ 1, 52 1, 53 1, 54 /* ECHO (8) */ 0, 55 /* ROUTERADVERT (9) */ 1, 56 /* ROUTERSOLICIT (10) */ 1, 57 /* TIME EXCEEDED (11) */ 1, 58 /* PARAMETER PROBLEM (12) */ 1, 59 /* TIMESTAMP (13) */ 0, 60 /* TIMESTAMP REPLY (14) */ 0, 61 /* INFO (15) */ 0, 62 /* INFO REPLY (16) */ 0, 63 /* ADDR MASK (17) */ 0, 64 /* ADDR MASK REPLY (18) */ 0 65 }; 66 67 /* 68 * Process a received ICMP message. 69 */ 70 void 71 icmp_input(struct mbuf *m, int hlen) 72 { 73 register struct icmp *icp; 74 register struct ip *ip=mtod(m, struct ip *); 75 int icmplen=ip->ip_len; 76 /* int code; */ 77 78 DEBUG_CALL("icmp_input"); 79 DEBUG_ARG("m = %lx", (long )m); 80 DEBUG_ARG("m_len = %d", m->m_len); 81 82 STAT(icmpstat.icps_received++); 83 84 /* 85 * Locate icmp structure in mbuf, and check 86 * that its not corrupted and of at least minimum length. 87 */ 88 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */ 89 STAT(icmpstat.icps_tooshort++); 90 freeit: 91 m_freem(m); 92 goto end_error; 93 } 94 95 m->m_len -= hlen; 96 m->m_data += hlen; 97 icp = mtod(m, struct icmp *); 98 if (cksum(m, icmplen)) { 99 STAT(icmpstat.icps_checksum++); 100 goto freeit; 101 } 102 m->m_len += hlen; 103 m->m_data -= hlen; 104 105 /* icmpstat.icps_inhist[icp->icmp_type]++; */ 106 /* code = icp->icmp_code; */ 107 108 DEBUG_ARG("icmp_type = %d", icp->icmp_type); 109 switch (icp->icmp_type) { 110 case ICMP_ECHO: 111 icp->icmp_type = ICMP_ECHOREPLY; 112 ip->ip_len += hlen; /* since ip_input subtracts this */ 113 if (ip->ip_dst.s_addr == alias_addr.s_addr) { 114 icmp_reflect(m); 115 } else { 116 struct socket *so; 117 struct sockaddr_in addr; 118 if ((so = socreate()) == NULL) goto freeit; 119 if(udp_attach(so) == -1) { 120 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n", 121 errno,strerror(errno))); 122 sofree(so); 123 m_free(m); 124 goto end_error; 125 } 126 so->so_m = m; 127 so->so_faddr = ip->ip_dst; 128 so->so_fport = htons(7); 129 so->so_laddr = ip->ip_src; 130 so->so_lport = htons(9); 131 so->so_iptos = ip->ip_tos; 132 so->so_type = IPPROTO_ICMP; 133 so->so_state = SS_ISFCONNECTED; 134 135 /* Send the packet */ 136 addr.sin_family = AF_INET; 137 if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) { 138 /* It's an alias */ 139 switch(ntohl(so->so_faddr.s_addr) & 0xff) { 140 case CTL_DNS: 141 addr.sin_addr = dns_addr; 142 break; 143 case CTL_ALIAS: 144 default: 145 addr.sin_addr = loopback_addr; 146 break; 147 } 148 } else { 149 addr.sin_addr = so->so_faddr; 150 } 151 addr.sin_port = so->so_fport; 152 if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0, 153 (struct sockaddr *)&addr, sizeof(addr)) == -1) { 154 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n", 155 errno,strerror(errno))); 156 icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno)); 157 udp_detach(so); 158 } 159 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */ 160 break; 161 case ICMP_UNREACH: 162 /* XXX? report error? close socket? */ 163 case ICMP_TIMXCEED: 164 case ICMP_PARAMPROB: 165 case ICMP_SOURCEQUENCH: 166 case ICMP_TSTAMP: 167 case ICMP_MASKREQ: 168 case ICMP_REDIRECT: 169 STAT(icmpstat.icps_notsupp++); 170 m_freem(m); 171 break; 172 173 default: 174 STAT(icmpstat.icps_badtype++); 175 m_freem(m); 176 } /* swith */ 177 178 end_error: 179 /* m is m_free()'d xor put in a socket xor or given to ip_send */ 180 return; 181 } 182 183 184 /* 185 * Send an ICMP message in response to a situation 186 * 187 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do). 188 * MUST NOT change this header information. 189 * MUST NOT reply to a multicast/broadcast IP address. 190 * MUST NOT reply to a multicast/broadcast MAC address. 191 * MUST reply to only the first fragment. 192 */ 193 /* 194 * Send ICMP_UNREACH back to the source regarding msrc. 195 * mbuf *msrc is used as a template, but is NOT m_free()'d. 196 * It is reported as the bad ip packet. The header should 197 * be fully correct and in host byte order. 198 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one 199 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548 200 */ 201 202 #define ICMP_MAXDATALEN (IP_MSS-28) 203 void 204 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize, 205 const char *message) 206 { 207 unsigned hlen, shlen, s_ip_len; 208 register struct ip *ip; 209 register struct icmp *icp; 210 register struct mbuf *m; 211 212 DEBUG_CALL("icmp_error"); 213 DEBUG_ARG("msrc = %lx", (long )msrc); 214 DEBUG_ARG("msrc_len = %d", msrc->m_len); 215 216 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error; 217 218 /* check msrc */ 219 if(!msrc) goto end_error; 220 ip = mtod(msrc, struct ip *); 221 #ifdef DEBUG 222 { char bufa[20], bufb[20]; 223 strcpy(bufa, inet_ntoa(ip->ip_src)); 224 strcpy(bufb, inet_ntoa(ip->ip_dst)); 225 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb)); 226 } 227 #endif 228 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */ 229 230 shlen=ip->ip_hl << 2; 231 s_ip_len=ip->ip_len; 232 if(ip->ip_p == IPPROTO_ICMP) { 233 icp = (struct icmp *)((char *)ip + shlen); 234 /* 235 * Assume any unknown ICMP type is an error. This isn't 236 * specified by the RFC, but think about it.. 237 */ 238 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error; 239 } 240 241 /* make a copy */ 242 if(!(m=m_get())) goto end_error; /* get mbuf */ 243 { int new_m_size; 244 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN; 245 if(new_m_size>m->m_size) m_inc(m, new_m_size); 246 } 247 memcpy(m->m_data, msrc->m_data, msrc->m_len); 248 m->m_len = msrc->m_len; /* copy msrc to m */ 249 250 /* make the header of the reply packet */ 251 ip = mtod(m, struct ip *); 252 hlen= sizeof(struct ip ); /* no options in reply */ 253 254 /* fill in icmp */ 255 m->m_data += hlen; 256 m->m_len -= hlen; 257 258 icp = mtod(m, struct icmp *); 259 260 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */ 261 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */ 262 s_ip_len=ICMP_MAXDATALEN; 263 264 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */ 265 266 /* min. size = 8+sizeof(struct ip)+8 */ 267 268 icp->icmp_type = type; 269 icp->icmp_code = code; 270 icp->icmp_id = 0; 271 icp->icmp_seq = 0; 272 273 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */ 274 HTONS(icp->icmp_ip.ip_len); 275 HTONS(icp->icmp_ip.ip_id); 276 HTONS(icp->icmp_ip.ip_off); 277 278 #ifdef DEBUG 279 if(message) { /* DEBUG : append message to ICMP packet */ 280 int message_len; 281 char *cpnt; 282 message_len=strlen(message); 283 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN; 284 cpnt=(char *)m->m_data+m->m_len; 285 memcpy(cpnt, message, message_len); 286 m->m_len+=message_len; 287 } 288 #endif 289 290 icp->icmp_cksum = 0; 291 icp->icmp_cksum = cksum(m, m->m_len); 292 293 m->m_data -= hlen; 294 m->m_len += hlen; 295 296 /* fill in ip */ 297 ip->ip_hl = hlen >> 2; 298 ip->ip_len = m->m_len; 299 300 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */ 301 302 ip->ip_ttl = MAXTTL; 303 ip->ip_p = IPPROTO_ICMP; 304 ip->ip_dst = ip->ip_src; /* ip adresses */ 305 ip->ip_src = alias_addr; 306 307 (void ) ip_output((struct socket *)NULL, m); 308 309 STAT(icmpstat.icps_reflect++); 310 311 end_error: 312 return; 313 } 314 #undef ICMP_MAXDATALEN 315 316 /* 317 * Reflect the ip packet back to the source 318 */ 319 void 320 icmp_reflect(struct mbuf *m) 321 { 322 register struct ip *ip = mtod(m, struct ip *); 323 int hlen = ip->ip_hl << 2; 324 int optlen = hlen - sizeof(struct ip ); 325 register struct icmp *icp; 326 327 /* 328 * Send an icmp packet back to the ip level, 329 * after supplying a checksum. 330 */ 331 m->m_data += hlen; 332 m->m_len -= hlen; 333 icp = mtod(m, struct icmp *); 334 335 icp->icmp_cksum = 0; 336 icp->icmp_cksum = cksum(m, ip->ip_len - hlen); 337 338 m->m_data -= hlen; 339 m->m_len += hlen; 340 341 /* fill in ip */ 342 if (optlen > 0) { 343 /* 344 * Strip out original options by copying rest of first 345 * mbuf's data back, and adjust the IP length. 346 */ 347 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen, 348 (unsigned )(m->m_len - hlen)); 349 hlen -= optlen; 350 ip->ip_hl = hlen >> 2; 351 ip->ip_len -= optlen; 352 m->m_len -= optlen; 353 } 354 355 ip->ip_ttl = MAXTTL; 356 { /* swap */ 357 struct in_addr icmp_dst; 358 icmp_dst = ip->ip_dst; 359 ip->ip_dst = ip->ip_src; 360 ip->ip_src = icmp_dst; 361 } 362 363 (void ) ip_output((struct socket *)NULL, m); 364 365 STAT(icmpstat.icps_reflect++); 366 } 367
