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         ip->ip_dst.s_addr == slirp->vnameserver_addr.s_addr) {
 157         icmp_reflect(m);
 158     } else if (slirp->restricted) {
 159         goto freeit;
 160     } else {
 161       struct socket *so;
 162       struct sockaddr_storage addr;
 163       so = socreate(slirp);
 164       if (icmp_send(so, m, hlen) == 0) {
 165         return;
 166       }
 167       if (udp_attach(so, AF_INET) == -1) {
 168         DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
 169                     errno,strerror(errno)));
 170         sofree(so);
 171         m_free(m);
 172         goto end_error;
 173       }
 174       so->so_m = m;
 175       so->so_ffamily = AF_INET;
 176       so->so_faddr = ip->ip_dst;
 177       so->so_fport = htons(7);
 178       so->so_lfamily = AF_INET;
 179       so->so_laddr = ip->ip_src;
 180       so->so_lport = htons(9);
 181       so->so_iptos = ip->ip_tos;
 182       so->so_type = IPPROTO_ICMP;
 183       so->so_state = SS_ISFCONNECTED;
 184
 185       /* Send the packet */
 186       addr = so->fhost.ss;
 187       sotranslate_out(so, &addr);
 188
 189       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 190                 (struct sockaddr *)&addr, sockaddr_size(&addr)) == -1) {
 191         DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 192                     errno,strerror(errno)));
 193         icmp_send_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_send_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_send_error");
 248   DEBUG_ARG("msrc = %p", 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   /* Do not reply to source-only IPs */
 266   if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
 267       goto end_error;
 268   }
 269
 270   shlen=ip->ip_hl << 2;
 271   s_ip_len=ip->ip_len;
 272   if(ip->ip_p == IPPROTO_ICMP) {
 273     icp = (struct icmp *)((char *)ip + shlen);
 274     /*
 275      *  Assume any unknown ICMP type is an error. This isn't
 276      *  specified by the RFC, but think about it..
 277      */
 278     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
 279   }
 280
 281   /* make a copy */
 282   m = m_get(msrc->slirp);
 283   if (!m) {
 284       goto end_error;
 285   }
 286
 287   { int new_m_size;
 288     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
 289     if(new_m_size>m->m_size) m_inc(m, new_m_size);
 290   }
 291   memcpy(m->m_data, msrc->m_data, msrc->m_len);
 292   m->m_len = msrc->m_len;                        /* copy msrc to m */
 293
 294   /* make the header of the reply packet */
 295   ip  = mtod(m, struct ip *);
 296   hlen= sizeof(struct ip );     /* no options in reply */
 297
 298   /* fill in icmp */
 299   m->m_data += hlen;
 300   m->m_len -= hlen;
 301
 302   icp = mtod(m, struct icmp *);
 303
 304   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
 305   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
 306     s_ip_len=ICMP_MAXDATALEN;
 307
 308   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
 309
 310   /* min. size = 8+sizeof(struct ip)+8 */
 311
 312   icp->icmp_type = type;
 313   icp->icmp_code = code;
 314   icp->icmp_id = 0;
 315   icp->icmp_seq = 0;
 316
 317   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
 318   HTONS(icp->icmp_ip.ip_len);
 319   HTONS(icp->icmp_ip.ip_id);
 320   HTONS(icp->icmp_ip.ip_off);
 321
 322 #ifdef DEBUG
 323   if(message) {           /* DEBUG : append message to ICMP packet */
 324     int message_len;
 325     char *cpnt;
 326     message_len=strlen(message);
 327     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
 328     cpnt=(char *)m->m_data+m->m_len;
 329     memcpy(cpnt, message, message_len);
 330     m->m_len+=message_len;
 331   }
 332 #endif
 333
 334   icp->icmp_cksum = 0;
 335   icp->icmp_cksum = cksum(m, m->m_len);
 336
 337   m->m_data -= hlen;
 338   m->m_len += hlen;
 339
 340   /* fill in ip */
 341   ip->ip_hl = hlen >> 2;
 342   ip->ip_len = m->m_len;
 343
 344   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
 345
 346   ip->ip_ttl = MAXTTL;
 347   ip->ip_p = IPPROTO_ICMP;
 348   ip->ip_dst = ip->ip_src;    /* ip addresses */
 349   ip->ip_src = m->slirp->vhost_addr;
 350
 351   (void ) ip_output((struct socket *)NULL, m);
 352
 353 end_error:
 354   return;
 355 }
 356 #undef ICMP_MAXDATALEN
 357
 358 /*
 359  * Reflect the ip packet back to the source
 360  */
 361 void
 362 icmp_reflect(struct mbuf *m)
 363 {
 364   register struct ip *ip = mtod(m, struct ip *);
 365   int hlen = ip->ip_hl << 2;
 366   int optlen = hlen - sizeof(struct ip );
 367   register struct icmp *icp;
 368
 369   /*
 370    * Send an icmp packet back to the ip level,
 371    * after supplying a checksum.
 372    */
 373   m->m_data += hlen;
 374   m->m_len -= hlen;
 375   icp = mtod(m, struct icmp *);
 376
 377   icp->icmp_type = ICMP_ECHOREPLY;
 378   icp->icmp_cksum = 0;
 379   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
 380
 381   m->m_data -= hlen;
 382   m->m_len += hlen;
 383
 384   /* fill in ip */
 385   if (optlen > 0) {
 386     /*
 387      * Strip out original options by copying rest of first
 388      * mbuf's data back, and adjust the IP length.
 389      */
 390     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 391             (unsigned )(m->m_len - hlen));
 392     hlen -= optlen;
 393     ip->ip_hl = hlen >> 2;
 394     ip->ip_len -= optlen;
 395     m->m_len -= optlen;
 396   }
 397
 398   ip->ip_ttl = MAXTTL;
 399   { /* swap */
 400     struct in_addr icmp_dst;
 401     icmp_dst = ip->ip_dst;
 402     ip->ip_dst = ip->ip_src;
 403     ip->ip_src = icmp_dst;
 404   }
 405
 406   (void ) ip_output((struct socket *)NULL, m);
 407 }
 408
 409 void icmp_receive(struct socket *so)
 410 {
 411     struct mbuf *m = so->so_m;
 412     struct ip *ip = mtod(m, struct ip *);
 413     int hlen = ip->ip_hl << 2;
 414     u_char error_code;
 415     struct icmp *icp;
 416     int id, len;
 417
 418     m->m_data += hlen;
 419     m->m_len -= hlen;
 420     icp = mtod(m, struct icmp *);
 421
 422     id = icp->icmp_id;
 423     len = qemu_recv(so->s, icp, M_ROOM(m), 0);
 424     /*
 425      * The behavior of reading SOCK_DGRAM+IPPROTO_ICMP sockets is inconsistent
 426      * between host OSes.  On Linux, only the ICMP header and payload is
 427      * included.  On macOS/Darwin, the socket acts like a raw socket and
 428      * includes the IP header as well.  On other BSDs, SOCK_DGRAM+IPPROTO_ICMP
 429      * sockets aren't supported at all, so we treat them like raw sockets.  It
 430      * isn't possible to detect this difference at runtime, so we must use an
 431      * #ifdef to determine if we need to remove the IP header.
 432      */
 433 #ifdef CONFIG_BSD
 434     if (len >= sizeof(struct ip)) {
 435         struct ip *inner_ip = mtod(m, struct ip *);
 436         int inner_hlen = inner_ip->ip_hl << 2;
 437         if (inner_hlen > len) {
 438             len = -1;
 439             errno = -EINVAL;
 440         } else {
 441             len -= inner_hlen;
 442             memmove(icp, (unsigned char *)icp + inner_hlen, len);
 443         }
 444     } else {
 445       len = -1;
 446       errno = -EINVAL;
 447     }
 448 #endif
 449     icp->icmp_id = id;
 450
 451     m->m_data -= hlen;
 452     m->m_len += hlen;
 453
 454     if (len == -1 || len == 0) {
 455         if (errno == ENETUNREACH) {
 456             error_code = ICMP_UNREACH_NET;
 457         } else {
 458             error_code = ICMP_UNREACH_HOST;
 459         }
 460         DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
 461                     strerror(errno)));
 462         icmp_send_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
 463     } else {
 464         icmp_reflect(so->so_m);
 465         so->so_m = NULL; /* Don't m_free() it again! */
 466     }
 467     icmp_detach(so);
 468 }