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. 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 /* The message sent when emulating PING */
  37 /* Be nice and tell them it's just a pseudo-ping packet */
  38 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
  39
  40 /* list of actions for icmp_error() on RX of an icmp message */
  41 static const int icmp_flush[19] = {
  42 /*  ECHO REPLY (0)  */   0,
  43                          1,
  44                          1,
  45 /* DEST UNREACH (3) */   1,
  46 /* SOURCE QUENCH (4)*/   1,
  47 /* REDIRECT (5) */       1,
  48                          1,
  49                          1,
  50 /* ECHO (8) */           0,
  51 /* ROUTERADVERT (9) */   1,
  52 /* ROUTERSOLICIT (10) */ 1,
  53 /* TIME EXCEEDED (11) */ 1,
  54 /* PARAMETER PROBLEM (12) */ 1,
  55 /* TIMESTAMP (13) */     0,
  56 /* TIMESTAMP REPLY (14) */ 0,
  57 /* INFO (15) */          0,
  58 /* INFO REPLY (16) */    0,
  59 /* ADDR MASK (17) */     0,
  60 /* ADDR MASK REPLY (18) */ 0
  61 };
  62
  63 void icmp_init(Slirp *slirp)
  64 {
  65     slirp->icmp.so_next = slirp->icmp.so_prev = &slirp->icmp;
  66     slirp->icmp_last_so = &slirp->icmp;
  67 }
  68
  69 static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
  70 {
  71     struct ip *ip = mtod(m, struct ip *);
  72     struct sockaddr_in addr;
  73
  74     so->s = qemu_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
  75     if (so->s == -1) {
  76         return -1;
  77     }
  78
  79     so->so_m = m;
  80     so->so_faddr = ip->ip_dst;
  81     so->so_laddr = ip->ip_src;
  82     so->so_iptos = ip->ip_tos;
  83     so->so_type = IPPROTO_ICMP;
  84     so->so_state = SS_ISFCONNECTED;
  85     so->so_expire = curtime + SO_EXPIRE;
  86
  87     addr.sin_family = AF_INET;
  88     addr.sin_addr = so->so_faddr;
  89
  90     insque(so, &so->slirp->icmp);
  91
  92     if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
  93                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
  94         DEBUG_MISC((dfd, "icmp_input icmp sendto tx errno = %d-%s\n",
  95                     errno, strerror(errno)));
  96         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
  97         icmp_detach(so);
  98     }
  99
 100     return 0;
 101 }
 102
 103 void icmp_detach(struct socket *so)
 104 {
 105     closesocket(so->s);
 106     sofree(so);
 107 }
 108
 109 /*
 110  * Process a received ICMP message.
 111  */
 112 void
 113 icmp_input(struct mbuf *m, int hlen)
 114 {
 115   register struct icmp *icp;
 116   register struct ip *ip=mtod(m, struct ip *);
 117   int icmplen=ip->ip_len;
 118   Slirp *slirp = m->slirp;
 119
 120   DEBUG_CALL("icmp_input");
 121   DEBUG_ARG("m = %lx", (long )m);
 122   DEBUG_ARG("m_len = %d", m->m_len);
 123
 124   /*
 125    * Locate icmp structure in mbuf, and check
 126    * that its not corrupted and of at least minimum length.
 127    */
 128   if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
 129   freeit:
 130     m_free(m);
 131     goto end_error;
 132   }
 133
 134   m->m_len -= hlen;
 135   m->m_data += hlen;
 136   icp = mtod(m, struct icmp *);
 137   if (cksum(m, icmplen)) {
 138     goto freeit;
 139   }
 140   m->m_len += hlen;
 141   m->m_data -= hlen;
 142
 143   DEBUG_ARG("icmp_type = %d", icp->icmp_type);
 144   switch (icp->icmp_type) {
 145   case ICMP_ECHO:
 146     ip->ip_len += hlen;              /* since ip_input subtracts this */
 147     if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
 148       icmp_reflect(m);
 149     } else if (slirp->restricted) {
 150         goto freeit;
 151     } else {
 152       struct socket *so;
 153       struct sockaddr_in addr;
 154       if ((so = socreate(slirp)) == NULL) goto freeit;
 155       if (icmp_send(so, m, hlen) == 0) {
 156         return;
 157       }
 158       if(udp_attach(so) == -1) {
 159         DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
 160                     errno,strerror(errno)));
 161         sofree(so);
 162         m_free(m);
 163         goto end_error;
 164       }
 165       so->so_m = m;
 166       so->so_faddr = ip->ip_dst;
 167       so->so_fport = htons(7);
 168       so->so_laddr = ip->ip_src;
 169       so->so_lport = htons(9);
 170       so->so_iptos = ip->ip_tos;
 171       so->so_type = IPPROTO_ICMP;
 172       so->so_state = SS_ISFCONNECTED;
 173
 174       /* Send the packet */
 175       addr.sin_family = AF_INET;
 176       if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
 177           slirp->vnetwork_addr.s_addr) {
 178         /* It's an alias */
 179         if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
 180           if (get_dns_addr(&addr.sin_addr) < 0)
 181             addr.sin_addr = loopback_addr;
 182         } else {
 183           addr.sin_addr = loopback_addr;
 184         }
 185       } else {
 186         addr.sin_addr = so->so_faddr;
 187       }
 188       addr.sin_port = so->so_fport;
 189       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 190                 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
 191         DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 192                     errno,strerror(errno)));
 193         icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 194         udp_detach(so);
 195       }
 196     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
 197     break;
 198   case ICMP_UNREACH:
 199     /* XXX? report error? close socket? */
 200   case ICMP_TIMXCEED:
 201   case ICMP_PARAMPROB:
 202   case ICMP_SOURCEQUENCH:
 203   case ICMP_TSTAMP:
 204   case ICMP_MASKREQ:
 205   case ICMP_REDIRECT:
 206     m_free(m);
 207     break;
 208
 209   default:
 210     m_free(m);
 211   } /* swith */
 212
 213 end_error:
 214   /* m is m_free()'d xor put in a socket xor or given to ip_send */
 215   return;
 216 }
 217
 218
 219 /*
 220  *      Send an ICMP message in response to a situation
 221  *
 222  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
 223  *                      MUST NOT change this header information.
 224  *                      MUST NOT reply to a multicast/broadcast IP address.
 225  *                      MUST NOT reply to a multicast/broadcast MAC address.
 226  *                      MUST reply to only the first fragment.
 227  */
 228 /*
 229  * Send ICMP_UNREACH back to the source regarding msrc.
 230  * mbuf *msrc is used as a template, but is NOT m_free()'d.
 231  * It is reported as the bad ip packet.  The header should
 232  * be fully correct and in host byte order.
 233  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
 234  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
 235  */
 236
 237 #define ICMP_MAXDATALEN (IP_MSS-28)
 238 void
 239 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
 240            const char *message)
 241 {
 242   unsigned hlen, shlen, s_ip_len;
 243   register struct ip *ip;
 244   register struct icmp *icp;
 245   register struct mbuf *m;
 246
 247   DEBUG_CALL("icmp_error");
 248   DEBUG_ARG("msrc = %lx", (long )msrc);
 249   DEBUG_ARG("msrc_len = %d", msrc->m_len);
 250
 251   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
 252
 253   /* check msrc */
 254   if(!msrc) goto end_error;
 255   ip = mtod(msrc, struct ip *);
 256 #ifdef DEBUG
 257   { char bufa[20], bufb[20];
 258     strcpy(bufa, inet_ntoa(ip->ip_src));
 259     strcpy(bufb, inet_ntoa(ip->ip_dst));
 260     DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
 261   }
 262 #endif
 263   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */
 264
 265   shlen=ip->ip_hl << 2;
 266   s_ip_len=ip->ip_len;
 267   if(ip->ip_p == IPPROTO_ICMP) {
 268     icp = (struct icmp *)((char *)ip + shlen);
 269     /*
 270      *  Assume any unknown ICMP type is an error. This isn't
 271      *  specified by the RFC, but think about it..
 272      */
 273     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
 274   }
 275
 276   /* make a copy */
 277   m = m_get(msrc->slirp);
 278   if (!m) {
 279       goto end_error;
 280   }
 281
 282   { int new_m_size;
 283     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
 284     if(new_m_size>m->m_size) m_inc(m, new_m_size);
 285   }
 286   memcpy(m->m_data, msrc->m_data, msrc->m_len);
 287   m->m_len = msrc->m_len;                        /* copy msrc to m */
 288
 289   /* make the header of the reply packet */
 290   ip  = mtod(m, struct ip *);
 291   hlen= sizeof(struct ip );     /* no options in reply */
 292
 293   /* fill in icmp */
 294   m->m_data += hlen;
 295   m->m_len -= hlen;
 296
 297   icp = mtod(m, struct icmp *);
 298
 299   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
 300   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
 301     s_ip_len=ICMP_MAXDATALEN;
 302
 303   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
 304
 305   /* min. size = 8+sizeof(struct ip)+8 */
 306
 307   icp->icmp_type = type;
 308   icp->icmp_code = code;
 309   icp->icmp_id = 0;
 310   icp->icmp_seq = 0;
 311
 312   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
 313   HTONS(icp->icmp_ip.ip_len);
 314   HTONS(icp->icmp_ip.ip_id);
 315   HTONS(icp->icmp_ip.ip_off);
 316
 317 #ifdef DEBUG
 318   if(message) {           /* DEBUG : append message to ICMP packet */
 319     int message_len;
 320     char *cpnt;
 321     message_len=strlen(message);
 322     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
 323     cpnt=(char *)m->m_data+m->m_len;
 324     memcpy(cpnt, message, message_len);
 325     m->m_len+=message_len;
 326   }
 327 #endif
 328
 329   icp->icmp_cksum = 0;
 330   icp->icmp_cksum = cksum(m, m->m_len);
 331
 332   m->m_data -= hlen;
 333   m->m_len += hlen;
 334
 335   /* fill in ip */
 336   ip->ip_hl = hlen >> 2;
 337   ip->ip_len = m->m_len;
 338
 339   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
 340
 341   ip->ip_ttl = MAXTTL;
 342   ip->ip_p = IPPROTO_ICMP;
 343   ip->ip_dst = ip->ip_src;    /* ip adresses */
 344   ip->ip_src = m->slirp->vhost_addr;
 345
 346   (void ) ip_output((struct socket *)NULL, m);
 347
 348 end_error:
 349   return;
 350 }
 351 #undef ICMP_MAXDATALEN
 352
 353 /*
 354  * Reflect the ip packet back to the source
 355  */
 356 void
 357 icmp_reflect(struct mbuf *m)
 358 {
 359   register struct ip *ip = mtod(m, struct ip *);
 360   int hlen = ip->ip_hl << 2;
 361   int optlen = hlen - sizeof(struct ip );
 362   register struct icmp *icp;
 363
 364   /*
 365    * Send an icmp packet back to the ip level,
 366    * after supplying a checksum.
 367    */
 368   m->m_data += hlen;
 369   m->m_len -= hlen;
 370   icp = mtod(m, struct icmp *);
 371
 372   icp->icmp_type = ICMP_ECHOREPLY;
 373   icp->icmp_cksum = 0;
 374   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
 375
 376   m->m_data -= hlen;
 377   m->m_len += hlen;
 378
 379   /* fill in ip */
 380   if (optlen > 0) {
 381     /*
 382      * Strip out original options by copying rest of first
 383      * mbuf's data back, and adjust the IP length.
 384      */
 385     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 386             (unsigned )(m->m_len - hlen));
 387     hlen -= optlen;
 388     ip->ip_hl = hlen >> 2;
 389     ip->ip_len -= optlen;
 390     m->m_len -= optlen;
 391   }
 392
 393   ip->ip_ttl = MAXTTL;
 394   { /* swap */
 395     struct in_addr icmp_dst;
 396     icmp_dst = ip->ip_dst;
 397     ip->ip_dst = ip->ip_src;
 398     ip->ip_src = icmp_dst;
 399   }
 400
 401   (void ) ip_output((struct socket *)NULL, m);
 402 }
 403
 404 void icmp_receive(struct socket *so)
 405 {
 406     struct mbuf *m = so->so_m;
 407     struct ip *ip = mtod(m, struct ip *);
 408     int hlen = ip->ip_hl << 2;
 409     u_char error_code;
 410     struct icmp *icp;
 411     int id, len;
 412
 413     m->m_data += hlen;
 414     m->m_len -= hlen;
 415     icp = mtod(m, struct icmp *);
 416
 417     id = icp->icmp_id;
 418     len = recv(so->s, icp, m->m_len, 0);
 419     icp->icmp_id = id;
 420
 421     m->m_data -= hlen;
 422     m->m_len += hlen;
 423
 424     if (len == -1 || len == 0) {
 425         if (errno == ENETUNREACH) {
 426             error_code = ICMP_UNREACH_NET;
 427         } else {
 428             error_code = ICMP_UNREACH_HOST;
 429         }
 430         DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
 431                     strerror(errno)));
 432         icmp_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
 433     } else {
 434         icmp_reflect(so->so_m);
 435         so->so_m = NULL; /* Don't m_free() it again! */
 436     }
 437     icmp_detach(so);
 438 }