LXR qemu/slirp/ip

   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 */
  39static 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 */
  42static 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
  64void 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
  70void icmp_cleanup(Slirp *slirp)
  71{
  72    while (slirp->icmp.so_next != &slirp->icmp) {
  73        icmp_detach(slirp->icmp.so_next);
  74    }
  75}
  76
  77static 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
 111void icmp_detach(struct socket *so)
 112{
 113    closesocket(so->s);
 114    sofree(so);
 115}
 116
 117/*
 118 * Process a received ICMP message.
 119 */
 120void
 121icmp_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      if ((so = socreate(slirp)) == NULL) goto freeit;
 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
 213end_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)
 238void
 239icmp_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
 353end_error:
 354  return;
 355}
 356#undef ICMP_MAXDATALEN
 357
 358/*
 359 * Reflect the ip packet back to the source
 360 */
 361void
 362icmp_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
 409void 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->m_len, 0);
 424    icp->icmp_id = id;
 425
 426    m->m_data -= hlen;
 427    m->m_len += hlen;
 428
 429    if (len == -1 || len == 0) {
 430        if (errno == ENETUNREACH) {
 431            error_code = ICMP_UNREACH_NET;
 432        } else {
 433            error_code = ICMP_UNREACH_HOST;
 434        }
 435        DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
 436                    strerror(errno)));
 437        icmp_send_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
 438    } else {
 439        icmp_reflect(so->so_m);
 440        so->so_m = NULL; /* Don't m_free() it again! */
 441    }
 442    icmp_detach(so);
 443}
 444