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 "qemu/osdep.h"
  34 #include "slirp.h"
  35 #include "ip_icmp.h"
  36
  37 /* The message sent when emulating PING */
  38 /* Be nice and tell them it's just a pseudo-ping packet */
  39 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
  40
  41 /* list of actions for icmp_send_error() on RX of an icmp message */
  42 static const int icmp_flush[19] = {
  43 /*  ECHO REPLY (0)  */   0,
  44                          1,
  45                          1,
  46 /* DEST UNREACH (3) */   1,
  47 /* SOURCE QUENCH (4)*/   1,
  48 /* REDIRECT (5) */       1,
  49                          1,
  50                          1,
  51 /* ECHO (8) */           0,
  52 /* ROUTERADVERT (9) */   1,
  53 /* ROUTERSOLICIT (10) */ 1,
  54 /* TIME EXCEEDED (11) */ 1,
  55 /* PARAMETER PROBLEM (12) */ 1,
  56 /* TIMESTAMP (13) */     0,
  57 /* TIMESTAMP REPLY (14) */ 0,
  58 /* INFO (15) */          0,
  59 /* INFO REPLY (16) */    0,
  60 /* ADDR MASK (17) */     0,
  61 /* ADDR MASK REPLY (18) */ 0
  62 };
  63
  64 void icmp_init(Slirp *slirp)
  65 {
  66     slirp->icmp.so_next = slirp->icmp.so_prev = &slirp->icmp;
  67     slirp->icmp_last_so = &slirp->icmp;
  68 }
  69
  70 void icmp_cleanup(Slirp *slirp)
  71 {
  72     while (slirp->icmp.so_next != &slirp->icmp) {
  73         icmp_detach(slirp->icmp.so_next);
  74     }
  75 }
  76
  77 static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
  78 {
  79     struct ip *ip = mtod(m, struct ip *);
  80     struct sockaddr_in addr;
  81
  82     so->s = qemu_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
  83     if (so->s == -1) {
  84         return -1;
  85     }
  86
  87     so->so_m = m;
  88     so->so_faddr = ip->ip_dst;
  89     so->so_laddr = ip->ip_src;
  90     so->so_iptos = ip->ip_tos;
  91     so->so_type = IPPROTO_ICMP;
  92     so->so_state = SS_ISFCONNECTED;
  93     so->so_expire = curtime + SO_EXPIRE;
  94
  95     addr.sin_family = AF_INET;
  96     addr.sin_addr = so->so_faddr;
  97
  98     insque(so, &so->slirp->icmp);
  99
 100     if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
 101                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
 102         DEBUG_MISC((dfd, "icmp_input icmp sendto tx errno = %d-%s\n",
 103                     errno, strerror(errno)));
 104         icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
 105         icmp_detach(so);
 106     }
 107
 108     return 0;
 109 }
 110
 111 void icmp_detach(struct socket *so)
 112 {
 113     closesocket(so->s);
 114     sofree(so);
 115 }
 116
 117 /*
 118  * Process a received ICMP message.
 119  */
 120 void
 121 icmp_input(struct mbuf *m, int hlen)
 122 {
 123   register struct icmp *icp;
 124   register struct ip *ip=mtod(m, struct ip *);
 125   int icmplen=ip->ip_len;
 126   Slirp *slirp = m->slirp;
 127
 128   DEBUG_CALL("icmp_input");
 129   DEBUG_ARG("m = %p", m);
 130   DEBUG_ARG("m_len = %d", m->m_len);
 131
 132   /*
 133    * Locate icmp structure in mbuf, and check
 134    * that its not corrupted and of at least minimum length.
 135    */
 136   if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
 137   freeit:
 138     m_free(m);
 139     goto end_error;
 140   }
 141
 142   m->m_len -= hlen;
 143   m->m_data += hlen;
 144   icp = mtod(m, struct icmp *);
 145   if (cksum(m, icmplen)) {
 146     goto freeit;
 147   }
 148   m->m_len += hlen;
 149   m->m_data -= hlen;
 150
 151   DEBUG_ARG("icmp_type = %d", icp->icmp_type);
 152   switch (icp->icmp_type) {
 153   case ICMP_ECHO:
 154     ip->ip_len += hlen;              /* since ip_input subtracts this */
 155     if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
 156       icmp_reflect(m);
 157     } else if (slirp->restricted) {
 158         goto freeit;
 159     } else {
 160       struct socket *so;
 161       struct sockaddr_storage addr;
 162       if ((so = socreate(slirp)) == NULL) goto freeit;
 163       if (icmp_send(so, m, hlen) == 0) {
 164         return;
 165       }
 166       if (udp_attach(so, AF_INET) == -1) {
 167         DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
 168                     errno,strerror(errno)));
 169         sofree(so);
 170         m_free(m);
 171         goto end_error;
 172       }
 173       so->so_m = m;
 174       so->so_ffamily = AF_INET;
 175       so->so_faddr = ip->ip_dst;
 176       so->so_fport = htons(7);
 177       so->so_lfamily = AF_INET;
 178       so->so_laddr = ip->ip_src;
 179       so->so_lport = htons(9);
 180       so->so_iptos = ip->ip_tos;
 181       so->so_type = IPPROTO_ICMP;
 182       so->so_state = SS_ISFCONNECTED;
 183
 184       /* Send the packet */
 185       addr = so->fhost.ss;
 186       sotranslate_out(so, &addr);
 187
 188       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 189                 (struct sockaddr *)&addr, sockaddr_size(&addr)) == -1) {
 190         DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 191                     errno,strerror(errno)));
 192         icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
 193         udp_detach(so);
 194       }
 195     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
 196     break;
 197   case ICMP_UNREACH:
 198     /* XXX? report error? close socket? */
 199   case ICMP_TIMXCEED:
 200   case ICMP_PARAMPROB:
 201   case ICMP_SOURCEQUENCH:
 202   case ICMP_TSTAMP:
 203   case ICMP_MASKREQ:
 204   case ICMP_REDIRECT:
 205     m_free(m);
 206     break;
 207
 208   default:
 209     m_free(m);
 210   } /* swith */
 211
 212 end_error:
 213   /* m is m_free()'d xor put in a socket xor or given to ip_send */
 214   return;
 215 }
 216
 217
 218 /*
 219  *      Send an ICMP message in response to a situation
 220  *
 221  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
 222  *                      MUST NOT change this header information.
 223  *                      MUST NOT reply to a multicast/broadcast IP address.
 224  *                      MUST NOT reply to a multicast/broadcast MAC address.
 225  *                      MUST reply to only the first fragment.
 226  */
 227 /*
 228  * Send ICMP_UNREACH back to the source regarding msrc.
 229  * mbuf *msrc is used as a template, but is NOT m_free()'d.
 230  * It is reported as the bad ip packet.  The header should
 231  * be fully correct and in host byte order.
 232  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
 233  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
 234  */
 235
 236 #define ICMP_MAXDATALEN (IP_MSS-28)
 237 void
 238 icmp_send_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
 239            const char *message)
 240 {
 241   unsigned hlen, shlen, s_ip_len;
 242   register struct ip *ip;
 243   register struct icmp *icp;
 244   register struct mbuf *m;
 245
 246   DEBUG_CALL("icmp_send_error");
 247   DEBUG_ARG("msrc = %p", msrc);
 248   DEBUG_ARG("msrc_len = %d", msrc->m_len);
 249
 250   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
 251
 252   /* check msrc */
 253   if(!msrc) goto end_error;
 254   ip = mtod(msrc, struct ip *);
 255 #ifdef DEBUG
 256   { char bufa[20], bufb[20];
 257     strcpy(bufa, inet_ntoa(ip->ip_src));
 258     strcpy(bufb, inet_ntoa(ip->ip_dst));
 259     DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
 260   }
 261 #endif
 262   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */
 263
 264   /* Do not reply to source-only IPs */
 265   if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
 266       goto end_error;
 267   }
 268
 269   shlen=ip->ip_hl << 2;
 270   s_ip_len=ip->ip_len;
 271   if(ip->ip_p == IPPROTO_ICMP) {
 272     icp = (struct icmp *)((char *)ip + shlen);
 273     /*
 274      *  Assume any unknown ICMP type is an error. This isn't
 275      *  specified by the RFC, but think about it..
 276      */
 277     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
 278   }
 279
 280   /* make a copy */
 281   m = m_get(msrc->slirp);
 282   if (!m) {
 283       goto end_error;
 284   }
 285
 286   { int new_m_size;
 287     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
 288     if(new_m_size>m->m_size) m_inc(m, new_m_size);
 289   }
 290   memcpy(m->m_data, msrc->m_data, msrc->m_len);
 291   m->m_len = msrc->m_len;                        /* copy msrc to m */
 292
 293   /* make the header of the reply packet */
 294   ip  = mtod(m, struct ip *);
 295   hlen= sizeof(struct ip );     /* no options in reply */
 296
 297   /* fill in icmp */
 298   m->m_data += hlen;
 299   m->m_len -= hlen;
 300
 301   icp = mtod(m, struct icmp *);
 302
 303   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
 304   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
 305     s_ip_len=ICMP_MAXDATALEN;
 306
 307   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
 308
 309   /* min. size = 8+sizeof(struct ip)+8 */
 310
 311   icp->icmp_type = type;
 312   icp->icmp_code = code;
 313   icp->icmp_id = 0;
 314   icp->icmp_seq = 0;
 315
 316   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
 317   HTONS(icp->icmp_ip.ip_len);
 318   HTONS(icp->icmp_ip.ip_id);
 319   HTONS(icp->icmp_ip.ip_off);
 320
 321 #ifdef DEBUG
 322   if(message) {           /* DEBUG : append message to ICMP packet */
 323     int message_len;
 324     char *cpnt;
 325     message_len=strlen(message);
 326     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
 327     cpnt=(char *)m->m_data+m->m_len;
 328     memcpy(cpnt, message, message_len);
 329     m->m_len+=message_len;
 330   }
 331 #endif
 332
 333   icp->icmp_cksum = 0;
 334   icp->icmp_cksum = cksum(m, m->m_len);
 335
 336   m->m_data -= hlen;
 337   m->m_len += hlen;
 338
 339   /* fill in ip */
 340   ip->ip_hl = hlen >> 2;
 341   ip->ip_len = m->m_len;
 342
 343   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
 344
 345   ip->ip_ttl = MAXTTL;
 346   ip->ip_p = IPPROTO_ICMP;
 347   ip->ip_dst = ip->ip_src;    /* ip addresses */
 348   ip->ip_src = m->slirp->vhost_addr;
 349
 350   (void ) ip_output((struct socket *)NULL, m);
 351
 352 end_error:
 353   return;
 354 }
 355 #undef ICMP_MAXDATALEN
 356
 357 /*
 358  * Reflect the ip packet back to the source
 359  */
 360 void
 361 icmp_reflect(struct mbuf *m)
 362 {
 363   register struct ip *ip = mtod(m, struct ip *);
 364   int hlen = ip->ip_hl << 2;
 365   int optlen = hlen - sizeof(struct ip );
 366   register struct icmp *icp;
 367
 368   /*
 369    * Send an icmp packet back to the ip level,
 370    * after supplying a checksum.
 371    */
 372   m->m_data += hlen;
 373   m->m_len -= hlen;
 374   icp = mtod(m, struct icmp *);
 375
 376   icp->icmp_type = ICMP_ECHOREPLY;
 377   icp->icmp_cksum = 0;
 378   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
 379
 380   m->m_data -= hlen;
 381   m->m_len += hlen;
 382
 383   /* fill in ip */
 384   if (optlen > 0) {
 385     /*
 386      * Strip out original options by copying rest of first
 387      * mbuf's data back, and adjust the IP length.
 388      */
 389     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 390             (unsigned )(m->m_len - hlen));
 391     hlen -= optlen;
 392     ip->ip_hl = hlen >> 2;
 393     ip->ip_len -= optlen;
 394     m->m_len -= optlen;
 395   }
 396
 397   ip->ip_ttl = MAXTTL;
 398   { /* swap */
 399     struct in_addr icmp_dst;
 400     icmp_dst = ip->ip_dst;
 401     ip->ip_dst = ip->ip_src;
 402     ip->ip_src = icmp_dst;
 403   }
 404
 405   (void ) ip_output((struct socket *)NULL, m);
 406 }
 407
 408 void icmp_receive(struct socket *so)
 409 {
 410     struct mbuf *m = so->so_m;
 411     struct ip *ip = mtod(m, struct ip *);
 412     int hlen = ip->ip_hl << 2;
 413     u_char error_code;
 414     struct icmp *icp;
 415     int id, len;
 416
 417     m->m_data += hlen;
 418     m->m_len -= hlen;
 419     icp = mtod(m, struct icmp *);
 420
 421     id = icp->icmp_id;
 422     len = qemu_recv(so->s, icp, m->m_len, 0);
 423     icp->icmp_id = id;
 424
 425     m->m_data -= hlen;
 426     m->m_len += hlen;
 427
 428     if (len == -1 || len == 0) {
 429         if (errno == ENETUNREACH) {
 430             error_code = ICMP_UNREACH_NET;
 431         } else {
 432             error_code = ICMP_UNREACH_HOST;
 433         }
 434         DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
 435                     strerror(errno)));
 436         icmp_send_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
 437     } else {
 438         icmp_reflect(so->so_m);
 439         so->so_m = NULL; /* Don't m_free() it again! */
 440     }
 441     icmp_detach(so);
 442 }