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 = %lx", (long )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_in 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) == -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_faddr = ip->ip_dst;
 174       so->so_fport = htons(7);
 175       so->so_laddr = ip->ip_src;
 176       so->so_lport = htons(9);
 177       so->so_iptos = ip->ip_tos;
 178       so->so_type = IPPROTO_ICMP;
 179       so->so_state = SS_ISFCONNECTED;
 180
 181       /* Send the packet */
 182       addr.sin_family = AF_INET;
 183       if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
 184           slirp->vnetwork_addr.s_addr) {
 185         /* It's an alias */
 186         if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
 187           if (get_dns_addr(&addr.sin_addr) < 0)
 188             addr.sin_addr = loopback_addr;
 189         } else {
 190           addr.sin_addr = loopback_addr;
 191         }
 192       } else {
 193         addr.sin_addr = so->so_faddr;
 194       }
 195       addr.sin_port = so->so_fport;
 196       if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
 197                 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
 198         DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 199                     errno,strerror(errno)));
 200         icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
 201         udp_detach(so);
 202       }
 203     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
 204     break;
 205   case ICMP_UNREACH:
 206     /* XXX? report error? close socket? */
 207   case ICMP_TIMXCEED:
 208   case ICMP_PARAMPROB:
 209   case ICMP_SOURCEQUENCH:
 210   case ICMP_TSTAMP:
 211   case ICMP_MASKREQ:
 212   case ICMP_REDIRECT:
 213     m_free(m);
 214     break;
 215
 216   default:
 217     m_free(m);
 218   } /* swith */
 219
 220 end_error:
 221   /* m is m_free()'d xor put in a socket xor or given to ip_send */
 222   return;
 223 }
 224
 225
 226 /*
 227  *      Send an ICMP message in response to a situation
 228  *
 229  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
 230  *                      MUST NOT change this header information.
 231  *                      MUST NOT reply to a multicast/broadcast IP address.
 232  *                      MUST NOT reply to a multicast/broadcast MAC address.
 233  *                      MUST reply to only the first fragment.
 234  */
 235 /*
 236  * Send ICMP_UNREACH back to the source regarding msrc.
 237  * mbuf *msrc is used as a template, but is NOT m_free()'d.
 238  * It is reported as the bad ip packet.  The header should
 239  * be fully correct and in host byte order.
 240  * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
 241  * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
 242  */
 243
 244 #define ICMP_MAXDATALEN (IP_MSS-28)
 245 void
 246 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
 247            const char *message)
 248 {
 249   unsigned hlen, shlen, s_ip_len;
 250   register struct ip *ip;
 251   register struct icmp *icp;
 252   register struct mbuf *m;
 253
 254   DEBUG_CALL("icmp_error");
 255   DEBUG_ARG("msrc = %lx", (long )msrc);
 256   DEBUG_ARG("msrc_len = %d", msrc->m_len);
 257
 258   if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
 259
 260   /* check msrc */
 261   if(!msrc) goto end_error;
 262   ip = mtod(msrc, struct ip *);
 263 #ifdef DEBUG
 264   { char bufa[20], bufb[20];
 265     strcpy(bufa, inet_ntoa(ip->ip_src));
 266     strcpy(bufb, inet_ntoa(ip->ip_dst));
 267     DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
 268   }
 269 #endif
 270   if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */
 271
 272   /* Do not reply to source-only IPs */
 273   if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
 274       goto end_error;
 275   }
 276
 277   shlen=ip->ip_hl << 2;
 278   s_ip_len=ip->ip_len;
 279   if(ip->ip_p == IPPROTO_ICMP) {
 280     icp = (struct icmp *)((char *)ip + shlen);
 281     /*
 282      *  Assume any unknown ICMP type is an error. This isn't
 283      *  specified by the RFC, but think about it..
 284      */
 285     if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
 286   }
 287
 288   /* make a copy */
 289   m = m_get(msrc->slirp);
 290   if (!m) {
 291       goto end_error;
 292   }
 293
 294   { int new_m_size;
 295     new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
 296     if(new_m_size>m->m_size) m_inc(m, new_m_size);
 297   }
 298   memcpy(m->m_data, msrc->m_data, msrc->m_len);
 299   m->m_len = msrc->m_len;                        /* copy msrc to m */
 300
 301   /* make the header of the reply packet */
 302   ip  = mtod(m, struct ip *);
 303   hlen= sizeof(struct ip );     /* no options in reply */
 304
 305   /* fill in icmp */
 306   m->m_data += hlen;
 307   m->m_len -= hlen;
 308
 309   icp = mtod(m, struct icmp *);
 310
 311   if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
 312   else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
 313     s_ip_len=ICMP_MAXDATALEN;
 314
 315   m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */
 316
 317   /* min. size = 8+sizeof(struct ip)+8 */
 318
 319   icp->icmp_type = type;
 320   icp->icmp_code = code;
 321   icp->icmp_id = 0;
 322   icp->icmp_seq = 0;
 323
 324   memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
 325   HTONS(icp->icmp_ip.ip_len);
 326   HTONS(icp->icmp_ip.ip_id);
 327   HTONS(icp->icmp_ip.ip_off);
 328
 329 #ifdef DEBUG
 330   if(message) {           /* DEBUG : append message to ICMP packet */
 331     int message_len;
 332     char *cpnt;
 333     message_len=strlen(message);
 334     if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
 335     cpnt=(char *)m->m_data+m->m_len;
 336     memcpy(cpnt, message, message_len);
 337     m->m_len+=message_len;
 338   }
 339 #endif
 340
 341   icp->icmp_cksum = 0;
 342   icp->icmp_cksum = cksum(m, m->m_len);
 343
 344   m->m_data -= hlen;
 345   m->m_len += hlen;
 346
 347   /* fill in ip */
 348   ip->ip_hl = hlen >> 2;
 349   ip->ip_len = m->m_len;
 350
 351   ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */
 352
 353   ip->ip_ttl = MAXTTL;
 354   ip->ip_p = IPPROTO_ICMP;
 355   ip->ip_dst = ip->ip_src;    /* ip adresses */
 356   ip->ip_src = m->slirp->vhost_addr;
 357
 358   (void ) ip_output((struct socket *)NULL, m);
 359
 360 end_error:
 361   return;
 362 }
 363 #undef ICMP_MAXDATALEN
 364
 365 /*
 366  * Reflect the ip packet back to the source
 367  */
 368 void
 369 icmp_reflect(struct mbuf *m)
 370 {
 371   register struct ip *ip = mtod(m, struct ip *);
 372   int hlen = ip->ip_hl << 2;
 373   int optlen = hlen - sizeof(struct ip );
 374   register struct icmp *icp;
 375
 376   /*
 377    * Send an icmp packet back to the ip level,
 378    * after supplying a checksum.
 379    */
 380   m->m_data += hlen;
 381   m->m_len -= hlen;
 382   icp = mtod(m, struct icmp *);
 383
 384   icp->icmp_type = ICMP_ECHOREPLY;
 385   icp->icmp_cksum = 0;
 386   icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
 387
 388   m->m_data -= hlen;
 389   m->m_len += hlen;
 390
 391   /* fill in ip */
 392   if (optlen > 0) {
 393     /*
 394      * Strip out original options by copying rest of first
 395      * mbuf's data back, and adjust the IP length.
 396      */
 397     memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
 398             (unsigned )(m->m_len - hlen));
 399     hlen -= optlen;
 400     ip->ip_hl = hlen >> 2;
 401     ip->ip_len -= optlen;
 402     m->m_len -= optlen;
 403   }
 404
 405   ip->ip_ttl = MAXTTL;
 406   { /* swap */
 407     struct in_addr icmp_dst;
 408     icmp_dst = ip->ip_dst;
 409     ip->ip_dst = ip->ip_src;
 410     ip->ip_src = icmp_dst;
 411   }
 412
 413   (void ) ip_output((struct socket *)NULL, m);
 414 }
 415
 416 void icmp_receive(struct socket *so)
 417 {
 418     struct mbuf *m = so->so_m;
 419     struct ip *ip = mtod(m, struct ip *);
 420     int hlen = ip->ip_hl << 2;
 421     u_char error_code;
 422     struct icmp *icp;
 423     int id, len;
 424
 425     m->m_data += hlen;
 426     m->m_len -= hlen;
 427     icp = mtod(m, struct icmp *);
 428
 429     id = icp->icmp_id;
 430     len = qemu_recv(so->s, icp, m->m_len, 0);
 431     icp->icmp_id = id;
 432
 433     m->m_data -= hlen;
 434     m->m_len += hlen;
 435
 436     if (len == -1 || len == 0) {
 437         if (errno == ENETUNREACH) {
 438             error_code = ICMP_UNREACH_NET;
 439         } else {
 440             error_code = ICMP_UNREACH_HOST;
 441         }
 442         DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
 443                     strerror(errno)));
 444         icmp_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
 445     } else {
 446         icmp_reflect(so->so_m);
 447         so->so_m = NULL; /* Don't m_free() it again! */
 448     }
 449     icmp_detach(so);
 450 }