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 "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 */
  38static 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 */
  41static 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
  63void 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
  69void icmp_cleanup(Slirp *slirp)
  70{
  71    while (slirp->icmp.so_next != &slirp->icmp) {
  72        icmp_detach(slirp->icmp.so_next);
  73    }
  74}
  75
  76static 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
 110void icmp_detach(struct socket *so)
 111{
 112    closesocket(so->s);
 113    sofree(so);
 114}
 115
 116/*
 117 * Process a received ICMP message.
 118 */
 119void
 120icmp_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
 220end_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)
 245void
 246icmp_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
 360end_error:
 361  return;
 362}
 363#undef ICMP_MAXDATALEN
 364
 365/*
 366 * Reflect the ip packet back to the source
 367 */
 368void
 369icmp_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
 416void 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}
 451