slirp/ip_icmp.c

   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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)ip_icmp.c   8.2 (Berkeley) 1/4/94
  34  * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
  35  */
  36
  37 #include "slirp.h"
  38 #include "ip_icmp.h"
  39
  40 struct icmpstat icmpstat;
  41
  42 /* The message sent when emulating PING */
  43 /* Be nice and tell them it's just a psuedo-ping packet */
  44 char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
  45
  46 /* list of actions for icmp_error() on RX of an icmp message */
  47 static int icmp_flush[19] = {
  48 /*  ECHO REPLY (0)  */   0,
  49                          1,
  50                          1,
  51 /* DEST UNREACH (3) */   1,
  52 /* SOURCE QUENCH (4)*/   1,
  53 /* REDIRECT (5) */       1,
  54                          1,
  55                          1,
  56 /* ECHO (8) */           0,
  57 /* ROUTERADVERT (9) */   1,
  58 /* ROUTERSOLICIT (10) */ 1,
  59 /* TIME EXCEEDED (11) */ 1,
  60 /* PARAMETER PROBLEM (12) */ 1,
  61 /* TIMESTAMP (13) */     0,
  62 /* TIMESTAMP REPLY (14) */ 0,
  63 /* INFO (15) */          0,
  64 /* INFO REPLY (16) */    0,
  65 /* ADDR MASK (17) */     0,
  66 /* ADDR MASK REPLY (18) */ 0
  67 };
  68
  69 /*
  70  * Process a received ICMP message.
  71  */
  72 void
  73 icmp_input(m, hlen)
  74      struct mbuf *m;
  75      int hlen;
  76 {
  77   register struct icmp *icp;
  78   register struct ip *ip=mtod(m, struct ip *);
  79   int icmplen=ip->ip_len;
  80   /* int code; */
  81
  82   DEBUG_CALL("icmp_input");
  83   DEBUG_ARG("m = %lx", (long )m);
  84   DEBUG_ARG("m_len = %d", m->m_len);
  85
  86   icmpstat.icps_received++;
  87
  88   /*
  89    * Locate icmp structure in mbuf, and check
  90    * that its not corrupted and of at least minimum length.
  91    */
  92   if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
  93     icmpstat.icps_tooshort++;
  94   freeit:
  95     m_freem(m);
  96     goto end_error;
  97   }
  98
  99   m->m_len -= hlen;
 100   m->m_data += hlen;
 101   icp = mtod(m, struct icmp *);
 102   if (cksum(m, icmplen)) {
 103     icmpstat.icps_checksum++;
 104     goto freeit;
 105   }
 106   m->m_len += hlen;
 107   m->m_data -= hlen;
 108
 109   /*    icmpstat.icps_inhist[icp->icmp_type]++; */
 110   /* code = icp->icmp_code; */
 111
 112   DEBUG_ARG("icmp_type = %d", icp->icmp_type);
 113   switch (icp->icmp_type) {
 114   case ICMP_ECHO:
 115     icp->icmp_type = ICMP_ECHOREPLY;
 116     ip->ip_len += hlen;              /* since ip_input subtracts this */
 117     if (ip->ip_dst.s_addr == our_addr.s_addr ||
 118         (ip->ip_dst.s_addr == (special_addr.s_addr|htonl(CTL_ALIAS))) ) {
 119       icmp_reflect(m);
 120     } else {
 121       struct socket *so;
 122       struct sockaddr_in addr;
 123       if ((so = socreate()) == NULL) goto freeit;
 124       if(udp_attach(so) == -1) {
 125         DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
 126                     errno,strerror(errno)));
 127         sofree(so);
 128         m_free(m);
 129         goto end_error;
 130       }
 131       so->so_m = m;
 132       so->so_faddr = ip->ip_dst;
 133       so->so_fport = htons(7);
 134       so->so_laddr = ip->ip_src;
 135       so->so_lport = htons(9);
 136       so->so_iptos = ip->ip_tos;
 137       so->so_type = IPPROTO_ICMP;
 138       so->so_state = SS_ISFCONNECTED;
 139
 140       /* Send the packet */
 141       addr.sin_family = AF_INET;
 142       if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 143         /* It's an alias */
 144         switch(ntohl(so->so_faddr.s_addr) & 0xff) {
 145         case CTL_DNS:
 146           addr.sin_addr = dns_addr;
 147           break;
 148         case CTL_ALIAS:
 149         default:
 150           addr.sin_addr = loopback_addr;
 151           break;
 152         }
 153       } else {
 154         addr.sin_addr = so->so_faddr;
 155       }
 156       addr.sin_port = so->so_fport;
 157       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 158                 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
 159         DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 160                     errno,strerror(errno)));
 161         icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 162         udp_detach(so);
 163       }
 164     } /* if ip->ip_dst.s_addr == our_addr.s_addr */
 165     break;
 166   case ICMP_UNREACH:
 167     /* XXX? report error? close socket? */
 168   case ICMP_TIMXCEED:
 169   case ICMP_PARAMPROB:
 170   case ICMP_SOURCEQUENCH:
 171   case ICMP_TSTAMP:
 172   case ICMP_MASKREQ:
 173   case ICMP_REDIRECT:
 174     icmpstat.icps_notsupp++;
 175     m_freem(m);
 176     break;
 177
 178   default:
 179     icmpstat.icps_badtype++;
 180     m_freem(m);
 181   } /* swith */
 182
 183 end_error:
 184   /* m is m_free()'d xor put in a socket xor or given to ip_send */
 185   return;
 186 }
 187
 188
 189 /*
 190  *      Send an ICMP message in response to a situation
 191  *
 192  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
 193  *                      MUST NOT change this header information.
 194  *                      MUST NOT reply to a multicast/broadcast IP address.
 195  *                      MUST NOT reply to a multicast/broadcast MAC address.
 196  *                      MUST reply to only the first fragment.
 197  */
 198 /*
 199  * Send ICMP_UNREACH back to the source regarding msrc.
 200  * mbuf *msrc is used as a template, but is NOT m_free()'d.
 201  * It is reported as the bad ip packet.  The header should
 202  * be fully correct and in host byte order.
 203  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
 204  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
 205  */
 206
 207 #define ICMP_MAXDATALEN (IP_MSS-28)
 208 void
 209 icmp_error(msrc, type, code, minsize, message)
 210      struct mbuf *msrc;
 211      u_char type;
 212      u_char code;
 213      int minsize;
 214      char *message;
 215 {
 216   unsigned hlen, shlen, s_ip_len;
 217   register struct ip *ip;
 218   register struct icmp *icp;
 219   register struct mbuf *m;
 220
 221   DEBUG_CALL("icmp_error");
 222   DEBUG_ARG("msrc = %lx", (long )msrc);
 223   DEBUG_ARG("msrc_len = %d", msrc->m_len);
 224
 225   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
 226
 227   /* check msrc */
 228   if(!msrc) goto end_error;
 229   ip = mtod(msrc, struct ip *);
 230 #if DEBUG
 231   { char bufa[20], bufb[20];
 232     strcpy(bufa, inet_ntoa(ip->ip_src));
 233     strcpy(bufb, inet_ntoa(ip->ip_dst));
 234     DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
 235   }
 236 #endif
 237   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */
 238
 239   shlen=ip->ip_hl << 2;
 240   s_ip_len=ip->ip_len;
 241   if(ip->ip_p == IPPROTO_ICMP) {
 242     icp = (struct icmp *)((char *)ip + shlen);
 243     /*
 244      *  Assume any unknown ICMP type is an error. This isn't
 245      *  specified by the RFC, but think about it..
 246      */
 247     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
 248   }
 249
 250   /* make a copy */
 251   if(!(m=m_get())) goto end_error;               /* get mbuf */
 252   { int new_m_size;
 253     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
 254     if(new_m_size>m->m_size) m_inc(m, new_m_size);
 255   }
 256   memcpy(m->m_data, msrc->m_data, msrc->m_len);
 257   m->m_len = msrc->m_len;                        /* copy msrc to m */
 258
 259   /* make the header of the reply packet */
 260   ip  = mtod(m, struct ip *);
 261   hlen= sizeof(struct ip );     /* no options in reply */
 262
 263   /* fill in icmp */
 264   m->m_data += hlen;
 265   m->m_len -= hlen;
 266
 267   icp = mtod(m, struct icmp *);
 268
 269   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
 270   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
 271     s_ip_len=ICMP_MAXDATALEN;
 272
 273   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
 274
 275   /* min. size = 8+sizeof(struct ip)+8 */
 276
 277   icp->icmp_type = type;
 278   icp->icmp_code = code;
 279   icp->icmp_id = 0;
 280   icp->icmp_seq = 0;
 281
 282   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
 283   HTONS(icp->icmp_ip.ip_len);
 284   HTONS(icp->icmp_ip.ip_id);
 285   HTONS(icp->icmp_ip.ip_off);
 286
 287 #if DEBUG
 288   if(message) {           /* DEBUG : append message to ICMP packet */
 289     int message_len;
 290     char *cpnt;
 291     message_len=strlen(message);
 292     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
 293     cpnt=(char *)m->m_data+m->m_len;
 294     memcpy(cpnt, message, message_len);
 295     m->m_len+=message_len;
 296   }
 297 #endif
 298
 299   icp->icmp_cksum = 0;
 300   icp->icmp_cksum = cksum(m, m->m_len);
 301
 302   m->m_data -= hlen;
 303   m->m_len += hlen;
 304
 305   /* fill in ip */
 306   ip->ip_hl = hlen >> 2;
 307   ip->ip_len = m->m_len;
 308
 309   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
 310
 311   ip->ip_ttl = MAXTTL;
 312   ip->ip_p = IPPROTO_ICMP;
 313   ip->ip_dst = ip->ip_src;    /* ip adresses */
 314   ip->ip_src = our_addr;
 315
 316   (void ) ip_output((struct socket *)NULL, m);
 317
 318   icmpstat.icps_reflect++;
 319
 320 end_error:
 321   return;
 322 }
 323 #undef ICMP_MAXDATALEN
 324
 325 /*
 326  * Reflect the ip packet back to the source
 327  */
 328 void
 329 icmp_reflect(m)
 330      struct mbuf *m;
 331 {
 332   register struct ip *ip = mtod(m, struct ip *);
 333   int hlen = ip->ip_hl << 2;
 334   int optlen = hlen - sizeof(struct ip );
 335   register struct icmp *icp;
 336
 337   /*
 338    * Send an icmp packet back to the ip level,
 339    * after supplying a checksum.
 340    */
 341   m->m_data += hlen;
 342   m->m_len -= hlen;
 343   icp = mtod(m, struct icmp *);
 344
 345   icp->icmp_cksum = 0;
 346   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
 347
 348   m->m_data -= hlen;
 349   m->m_len += hlen;
 350
 351   /* fill in ip */
 352   if (optlen > 0) {
 353     /*
 354      * Strip out original options by copying rest of first
 355      * mbuf's data back, and adjust the IP length.
 356      */
 357     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 358             (unsigned )(m->m_len - hlen));
 359     hlen -= optlen;
 360     ip->ip_hl = hlen >> 2;
 361     ip->ip_len -= optlen;
 362     m->m_len -= optlen;
 363   }
 364
 365   ip->ip_ttl = MAXTTL;
 366   { /* swap */
 367     struct in_addr icmp_dst;
 368     icmp_dst = ip->ip_dst;
 369     ip->ip_dst = ip->ip_src;
 370     ip->ip_src = icmp_dst;
 371   }
 372
 373   (void ) ip_output((struct socket *)NULL, m);
 374
 375   icmpstat.icps_reflect++;
 376 }