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 void icmp_cleanup(Slirp *slirp)
  70 {
  71     while (slirp->icmp.so_next != &slirp->icmp) {
  72         icmp_detach(slirp->icmp.so_next);
  73     }
  74 }
  75
  76 static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
  77 {
  78     struct ip *ip = mtod(m, struct ip *);
  79     struct sockaddr_in addr;
  80
  81     so->s = qemu_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
  82     if (so->s == -1) {
  83         return -1;
  84     }
  85
  86     so->so_m = m;
  87     so->so_faddr = ip->ip_dst;
  88     so->so_laddr = ip->ip_src;
  89     so->so_iptos = ip->ip_tos;
  90     so->so_type = IPPROTO_ICMP;
  91     so->so_state = SS_ISFCONNECTED;
  92     so->so_expire = curtime + SO_EXPIRE;
  93
  94     addr.sin_family = AF_INET;
  95     addr.sin_addr = so->so_faddr;
  96
  97     insque(so, &so->slirp->icmp);
  98
  99     if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
 100                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
 101         DEBUG_MISC((dfd, "icmp_input icmp sendto tx errno = %d-%s\n",
 102                     errno, strerror(errno)));
 103         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
 104         icmp_detach(so);
 105     }
 106
 107     return 0;
 108 }
 109
 110 void icmp_detach(struct socket *so)
 111 {
 112     closesocket(so->s);
 113     sofree(so);
 114 }
 115
 116 /*
 117  * Process a received ICMP message.
 118  */
 119 void
 120 icmp_input(struct mbuf *m, int hlen)
 121 {
 122   register struct icmp *icp;
 123   register struct ip *ip=mtod(m, struct ip *);
 124   int icmplen=ip->ip_len;
 125   Slirp *slirp = m->slirp;
 126
 127   DEBUG_CALL("icmp_input");
 128   DEBUG_ARG("m = %p", m);
 129   DEBUG_ARG("m_len = %d", m->m_len);
 130
 131   /*
 132    * Locate icmp structure in mbuf, and check
 133    * that its not corrupted and of at least minimum length.
 134    */
 135   if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
 136   freeit:
 137     m_free(m);
 138     goto end_error;
 139   }
 140
 141   m->m_len -= hlen;
 142   m->m_data += hlen;
 143   icp = mtod(m, struct icmp *);
 144   if (cksum(m, icmplen)) {
 145     goto freeit;
 146   }
 147   m->m_len += hlen;
 148   m->m_data -= hlen;
 149
 150   DEBUG_ARG("icmp_type = %d", icp->icmp_type);
 151   switch (icp->icmp_type) {
 152   case ICMP_ECHO:
 153     ip->ip_len += hlen;              /* since ip_input subtracts this */
 154     if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
 155       icmp_reflect(m);
 156     } else if (slirp->restricted) {
 157         goto freeit;
 158     } else {
 159       struct socket *so;
 160       struct sockaddr_storage addr;
 161       if ((so = socreate(slirp)) == NULL) goto freeit;
 162       if (icmp_send(so, m, hlen) == 0) {
 163         return;
 164       }
 165       if (udp_attach(so, AF_INET) == -1) {
 166         DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
 167                     errno,strerror(errno)));
 168         sofree(so);
 169         m_free(m);
 170         goto end_error;
 171       }
 172       so->so_m = m;
 173       so->so_ffamily = AF_INET;
 174       so->so_faddr = ip->ip_dst;
 175       so->so_fport = htons(7);
 176       so->so_lfamily = AF_INET;
 177       so->so_laddr = ip->ip_src;
 178       so->so_lport = htons(9);
 179       so->so_iptos = ip->ip_tos;
 180       so->so_type = IPPROTO_ICMP;
 181       so->so_state = SS_ISFCONNECTED;
 182
 183       /* Send the packet */
 184       addr = so->fhost.ss;
 185       sotranslate_out(so, &addr);
 186
 187       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 188                 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
 189         DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 190                     errno,strerror(errno)));
 191         icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 192         udp_detach(so);
 193       }
 194     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
 195     break;
 196   case ICMP_UNREACH:
 197     /* XXX? report error? close socket? */
 198   case ICMP_TIMXCEED:
 199   case ICMP_PARAMPROB:
 200   case ICMP_SOURCEQUENCH:
 201   case ICMP_TSTAMP:
 202   case ICMP_MASKREQ:
 203   case ICMP_REDIRECT:
 204     m_free(m);
 205     break;
 206
 207   default:
 208     m_free(m);
 209   } /* swith */
 210
 211 end_error:
 212   /* m is m_free()'d xor put in a socket xor or given to ip_send */
 213   return;
 214 }
 215
 216
 217 /*
 218  *      Send an ICMP message in response to a situation
 219  *
 220  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
 221  *                      MUST NOT change this header information.
 222  *                      MUST NOT reply to a multicast/broadcast IP address.
 223  *                      MUST NOT reply to a multicast/broadcast MAC address.
 224  *                      MUST reply to only the first fragment.
 225  */
 226 /*
 227  * Send ICMP_UNREACH back to the source regarding msrc.
 228  * mbuf *msrc is used as a template, but is NOT m_free()'d.
 229  * It is reported as the bad ip packet.  The header should
 230  * be fully correct and in host byte order.
 231  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
 232  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
 233  */
 234
 235 #define ICMP_MAXDATALEN (IP_MSS-28)
 236 void
 237 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
 238            const char *message)
 239 {
 240   unsigned hlen, shlen, s_ip_len;
 241   register struct ip *ip;
 242   register struct icmp *icp;
 243   register struct mbuf *m;
 244
 245   DEBUG_CALL("icmp_error");
 246   DEBUG_ARG("msrc = %p", msrc);
 247   DEBUG_ARG("msrc_len = %d", msrc->m_len);
 248
 249   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
 250
 251   /* check msrc */
 252   if(!msrc) goto end_error;
 253   ip = mtod(msrc, struct ip *);
 254 #ifdef DEBUG
 255   { char bufa[20], bufb[20];
 256     strcpy(bufa, inet_ntoa(ip->ip_src));
 257     strcpy(bufb, inet_ntoa(ip->ip_dst));
 258     DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
 259   }
 260 #endif
 261   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */
 262
 263   /* Do not reply to source-only IPs */
 264   if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
 265       goto end_error;
 266   }
 267
 268   shlen=ip->ip_hl << 2;
 269   s_ip_len=ip->ip_len;
 270   if(ip->ip_p == IPPROTO_ICMP) {
 271     icp = (struct icmp *)((char *)ip + shlen);
 272     /*
 273      *  Assume any unknown ICMP type is an error. This isn't
 274      *  specified by the RFC, but think about it..
 275      */
 276     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
 277   }
 278
 279   /* make a copy */
 280   m = m_get(msrc->slirp);
 281   if (!m) {
 282       goto end_error;
 283   }
 284
 285   { int new_m_size;
 286     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
 287     if(new_m_size>m->m_size) m_inc(m, new_m_size);
 288   }
 289   memcpy(m->m_data, msrc->m_data, msrc->m_len);
 290   m->m_len = msrc->m_len;                        /* copy msrc to m */
 291
 292   /* make the header of the reply packet */
 293   ip  = mtod(m, struct ip *);
 294   hlen= sizeof(struct ip );     /* no options in reply */
 295
 296   /* fill in icmp */
 297   m->m_data += hlen;
 298   m->m_len -= hlen;
 299
 300   icp = mtod(m, struct icmp *);
 301
 302   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
 303   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
 304     s_ip_len=ICMP_MAXDATALEN;
 305
 306   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
 307
 308   /* min. size = 8+sizeof(struct ip)+8 */
 309
 310   icp->icmp_type = type;
 311   icp->icmp_code = code;
 312   icp->icmp_id = 0;
 313   icp->icmp_seq = 0;
 314
 315   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
 316   HTONS(icp->icmp_ip.ip_len);
 317   HTONS(icp->icmp_ip.ip_id);
 318   HTONS(icp->icmp_ip.ip_off);
 319
 320 #ifdef DEBUG
 321   if(message) {           /* DEBUG : append message to ICMP packet */
 322     int message_len;
 323     char *cpnt;
 324     message_len=strlen(message);
 325     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
 326     cpnt=(char *)m->m_data+m->m_len;
 327     memcpy(cpnt, message, message_len);
 328     m->m_len+=message_len;
 329   }
 330 #endif
 331
 332   icp->icmp_cksum = 0;
 333   icp->icmp_cksum = cksum(m, m->m_len);
 334
 335   m->m_data -= hlen;
 336   m->m_len += hlen;
 337
 338   /* fill in ip */
 339   ip->ip_hl = hlen >> 2;
 340   ip->ip_len = m->m_len;
 341
 342   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
 343
 344   ip->ip_ttl = MAXTTL;
 345   ip->ip_p = IPPROTO_ICMP;
 346   ip->ip_dst = ip->ip_src;    /* ip addresses */
 347   ip->ip_src = m->slirp->vhost_addr;
 348
 349   (void ) ip_output((struct socket *)NULL, m);
 350
 351 end_error:
 352   return;
 353 }
 354 #undef ICMP_MAXDATALEN
 355
 356 /*
 357  * Reflect the ip packet back to the source
 358  */
 359 void
 360 icmp_reflect(struct mbuf *m)
 361 {
 362   register struct ip *ip = mtod(m, struct ip *);
 363   int hlen = ip->ip_hl << 2;
 364   int optlen = hlen - sizeof(struct ip );
 365   register struct icmp *icp;
 366
 367   /*
 368    * Send an icmp packet back to the ip level,
 369    * after supplying a checksum.
 370    */
 371   m->m_data += hlen;
 372   m->m_len -= hlen;
 373   icp = mtod(m, struct icmp *);
 374
 375   icp->icmp_type = ICMP_ECHOREPLY;
 376   icp->icmp_cksum = 0;
 377   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
 378
 379   m->m_data -= hlen;
 380   m->m_len += hlen;
 381
 382   /* fill in ip */
 383   if (optlen > 0) {
 384     /*
 385      * Strip out original options by copying rest of first
 386      * mbuf's data back, and adjust the IP length.
 387      */
 388     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 389             (unsigned )(m->m_len - hlen));
 390     hlen -= optlen;
 391     ip->ip_hl = hlen >> 2;
 392     ip->ip_len -= optlen;
 393     m->m_len -= optlen;
 394   }
 395
 396   ip->ip_ttl = MAXTTL;
 397   { /* swap */
 398     struct in_addr icmp_dst;
 399     icmp_dst = ip->ip_dst;
 400     ip->ip_dst = ip->ip_src;
 401     ip->ip_src = icmp_dst;
 402   }
 403
 404   (void ) ip_output((struct socket *)NULL, m);
 405 }
 406
 407 void icmp_receive(struct socket *so)
 408 {
 409     struct mbuf *m = so->so_m;
 410     struct ip *ip = mtod(m, struct ip *);
 411     int hlen = ip->ip_hl << 2;
 412     u_char error_code;
 413     struct icmp *icp;
 414     int id, len;
 415
 416     m->m_data += hlen;
 417     m->m_len -= hlen;
 418     icp = mtod(m, struct icmp *);
 419
 420     id = icp->icmp_id;
 421     len = qemu_recv(so->s, icp, m->m_len, 0);
 422     icp->icmp_id = id;
 423
 424     m->m_data -= hlen;
 425     m->m_len += hlen;
 426
 427     if (len == -1 || len == 0) {
 428         if (errno == ENETUNREACH) {
 429             error_code = ICMP_UNREACH_NET;
 430         } else {
 431             error_code = ICMP_UNREACH_HOST;
 432         }
 433         DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
 434                     strerror(errno)));
 435         icmp_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
 436     } else {
 437         icmp_reflect(so->so_m);
 438         so->so_m = NULL; /* Don't m_free() it again! */
 439     }
 440     icmp_detach(so);
 441 }