common/nit.c

   1 /* nit.c
   2
   3    Network Interface Tap (NIT) network interface code, by Ted Lemon
   4    with one crucial tidbit of help from Stu Grossmen. */
   5
   6 /*
   7  * Copyright (c) 1996-2000 Internet Software Consortium.
   8  * All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of The Internet Software Consortium nor the names
  20  *    of its contributors may be used to endorse or promote products derived
  21  *    from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
  24  * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  25  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  26  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  27  * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
  28  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  30  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  31  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  32  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  33  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  34  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  * This software has been written for the Internet Software Consortium
  38  * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
  39  * To learn more about the Internet Software Consortium, see
  40  * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
  41  * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
  42  * ``http://www.nominum.com''.
  43  */
  44
  45 #ifndef lint
  46 static char copyright[] =
  47 "$Id: nit.c,v 1.28 2000/03/17 03:59:01 mellon Exp $ Copyright (c) 1996-2000 The Internet Software Consortium.  All rights reserved.\n";
  48 #endif /* not lint */
  49
  50 #include "dhcpd.h"
  51 #if defined (USE_NIT_SEND) || defined (USE_NIT_RECEIVE)
  52 #include <sys/ioctl.h>
  53 #include <sys/uio.h>
  54
  55 #include <sys/time.h>
  56 #include <net/nit.h>
  57 #include <net/nit_if.h>
  58 #include <net/nit_pf.h>
  59 #include <net/nit_buf.h>
  60 #include <sys/stropts.h>
  61 #include <net/packetfilt.h>
  62
  63 #include <netinet/in_systm.h>
  64 #include "includes/netinet/ip.h"
  65 #include "includes/netinet/udp.h"
  66 #include "includes/netinet/if_ether.h"
  67
  68 /* Reinitializes the specified interface after an address change.   This
  69    is not required for packet-filter APIs. */
  70
  71 #ifdef USE_NIT_SEND
  72 void if_reinitialize_send (info)
  73         struct interface_info *info;
  74 {
  75 }
  76 #endif
  77
  78 #ifdef USE_NIT_RECEIVE
  79 void if_reinitialize_receive (info)
  80         struct interface_info *info;
  81 {
  82 }
  83 #endif
  84
  85 /* Called by get_interface_list for each interface that's discovered.
  86    Opens a packet filter for each interface and adds it to the select
  87    mask. */
  88
  89 int if_register_nit (info)
  90         struct interface_info *info;
  91 {
  92         int sock;
  93         char filename[50];
  94         struct ifreq ifr;
  95         struct strioctl sio;
  96
  97         /* Open a NIT device */
  98         sock = open ("/dev/nit", O_RDWR);
  99         if (sock < 0)
 100                 log_fatal ("Can't open NIT device for %s: %m", info -> name);
 101
 102         /* Set the NIT device to point at this interface. */
 103         sio.ic_cmd = NIOCBIND;
 104         sio.ic_len = sizeof *(info -> ifp);
 105         sio.ic_dp = (char *)(info -> ifp);
 106         sio.ic_timout = INFTIM;
 107         if (ioctl (sock, I_STR, &sio) < 0)
 108                 log_fatal ("Can't attach interface %s to nit device: %m",
 109                        info -> name);
 110
 111         /* Get the low-level address... */
 112         sio.ic_cmd = SIOCGIFADDR;
 113         sio.ic_len = sizeof ifr;
 114         sio.ic_dp = (char *)&ifr;
 115         sio.ic_timout = INFTIM;
 116         if (ioctl (sock, I_STR, &sio) < 0)
 117                 log_fatal ("Can't get physical layer address for %s: %m",
 118                        info -> name);
 119
 120         /* XXX code below assumes ethernet interface! */
 121         info -> hw_address.hlen = 7;
 122         info -> hw_address.hbuf [0] = ARPHRD_ETHER;
 123         memcpy (&info -> hw_address.jbuf [1],
 124                 ifr.ifr_ifru.ifru_addr.sa_data, 6);
 125
 126         if (ioctl (sock, I_PUSH, "pf") < 0)
 127                 log_fatal ("Can't push packet filter onto NIT for %s: %m",
 128                        info -> name);
 129
 130         return sock;
 131 }
 132 #endif /* USE_NIT_SEND || USE_NIT_RECEIVE */
 133
 134 #ifdef USE_NIT_SEND
 135 void if_register_send (info)
 136         struct interface_info *info;
 137 {
 138         /* If we're using the nit API for sending and receiving,
 139            we don't need to register this interface twice. */
 140 #ifndef USE_NIT_RECEIVE
 141         struct packetfilt pf;
 142         struct strioctl sio;
 143
 144         info -> wfdesc = if_register_nit (info);
 145
 146         pf.Pf_Priority = 0;
 147         pf.Pf_FilterLen = 1;
 148         pf.Pf_Filter [0] = ENF_PUSHZERO;
 149
 150         /* Set up an NIT filter that rejects everything... */
 151         sio.ic_cmd = NIOCSETF;
 152         sio.ic_len = sizeof pf;
 153         sio.ic_dp = (char *)&pf;
 154         sio.ic_timout = INFTIM;
 155         if (ioctl (info -> wfdesc, I_STR, &sio) < 0)
 156                 log_fatal ("Can't set NIT filter: %m");
 157 #else
 158         info -> wfdesc = info -> rfdesc;
 159 #endif
 160         if (!quiet_interface_discovery)
 161                 log_info ("Sending on   NIT/%s%s%s",
 162                       print_hw_addr (info -> hw_address.hbuf [0],
 163                                      info -> hw_address.hlen - 1,
 164                                      &info -> hw_address.hbuf [1]),
 165                       (info -> shared_network ? "/" : ""),
 166                       (info -> shared_network ?
 167                        info -> shared_network -> name : ""));
 168 }
 169
 170 void if_deregister_send (info)
 171         struct interface_info *info;
 172 {
 173         /* If we're using the nit API for sending and receiving,
 174            we don't need to register this interface twice. */
 175 #ifndef USE_NIT_RECEIVE
 176         close (info -> wfdesc);
 177 #endif
 178         info -> wfdesc = -1;
 179         if (!quiet_interface_discovery)
 180                 log_info ("Disabling output on NIT/%s%s%s",
 181                       print_hw_addr (info -> hw_address.hbuf [0],
 182                                      info -> hw_address.hlen - 1,
 183                                      &info -> hw_address.hbuf [1]),
 184                       (info -> shared_network ? "/" : ""),
 185                       (info -> shared_network ?
 186                        info -> shared_network -> name : ""));
 187 }
 188 #endif /* USE_NIT_SEND */
 189
 190 #ifdef USE_NIT_RECEIVE
 191 /* Packet filter program...
 192    XXX Changes to the filter program may require changes to the constant
 193    offsets used in if_register_send to patch the NIT program! XXX */
 194
 195 void if_register_receive (info)
 196         struct interface_info *info;
 197 {
 198         int flag = 1;
 199         u_int32_t x;
 200         struct packetfilt pf;
 201         struct strioctl sio;
 202         u_int16_t addr [2];
 203         struct timeval t;
 204
 205         /* Open a NIT device and hang it on this interface... */
 206         info -> rfdesc = if_register_nit (info);
 207
 208         /* Set the snap length to 0, which means always take the whole
 209            packet. */
 210         x = 0;
 211         if (ioctl (info -> rfdesc, NIOCSSNAP, &x) < 0)
 212                 log_fatal ("Can't set NIT snap length on %s: %m", info -> name);
 213
 214         /* Set the stream to byte stream mode */
 215         if (ioctl (info -> rfdesc, I_SRDOPT, RMSGN) != 0)
 216                 log_info ("I_SRDOPT failed on %s: %m", info -> name);
 217
 218 #if 0
 219         /* Push on the chunker... */
 220         if (ioctl (info -> rfdesc, I_PUSH, "nbuf") < 0)
 221                 log_fatal ("Can't push chunker onto NIT STREAM: %m");
 222
 223         /* Set the timeout to zero. */
 224         t.tv_sec = 0;
 225         t.tv_usec = 0;
 226         if (ioctl (info -> rfdesc, NIOCSTIME, &t) < 0)
 227                 log_fatal ("Can't set chunk timeout: %m");
 228 #endif
 229
 230         /* Ask for no header... */
 231         x = 0;
 232         if (ioctl (info -> rfdesc, NIOCSFLAGS, &x) < 0)
 233                 log_fatal ("Can't set NIT flags on %s: %m", info -> name);
 234
 235         /* Set up the NIT filter program. */
 236         /* XXX Unlike the BPF filter program, this one won't work if the
 237            XXX IP packet is fragmented or if there are options on the IP
 238            XXX header. */
 239         pf.Pf_Priority = 0;
 240         pf.Pf_FilterLen = 0;
 241
 242         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 6;
 243         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND;
 244         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (ETHERTYPE_IP);
 245         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT;
 246         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (IPPROTO_UDP);
 247         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 11;
 248         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_AND;
 249         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (0xFF);
 250         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_CAND;
 251         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 18;
 252         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND;
 253         pf.Pf_Filter [pf.Pf_FilterLen++] = local_port;
 254
 255         /* Install the filter... */
 256         sio.ic_cmd = NIOCSETF;
 257         sio.ic_len = sizeof pf;
 258         sio.ic_dp = (char *)&pf;
 259         sio.ic_timout = INFTIM;
 260         if (ioctl (info -> rfdesc, I_STR, &sio) < 0)
 261                 log_fatal ("Can't set NIT filter on %s: %m", info -> name);
 262
 263         if (!quiet_interface_discovery)
 264                 log_info ("Listening on NIT/%s%s%s",
 265                       print_hw_addr (info -> hw_address.hbuf [0],
 266                                      info -> hw_address.hlen - 1,
 267                                      &info -> hw_address.hbuf [1]),
 268                       (info -> shared_network ? "/" : ""),
 269                       (info -> shared_network ?
 270                        info -> shared_network -> name : ""));
 271 }
 272
 273 void if_deregister_receive (info)
 274         struct interface_info *info;
 275 {
 276         /* If we're using the nit API for sending and receiving,
 277            we don't need to register this interface twice. */
 278         close (info -> rfdesc);
 279         info -> rfdesc = -1;
 280
 281         if (!quiet_interface_discovery)
 282                 log_info ("Disabling input on NIT/%s%s%s",
 283                       print_hw_addr (info -> hw_address.hbuf [0],
 284                                      info -> hw_address.hlen - 1,
 285                                      &info -> hw_address.hbuf [1]),
 286                       (info -> shared_network ? "/" : ""),
 287                       (info -> shared_network ?
 288                        info -> shared_network -> name : ""));
 289 }
 290 #endif /* USE_NIT_RECEIVE */
 291
 292 #ifdef USE_NIT_SEND
 293 ssize_t send_packet (interface, packet, raw, len, from, to, hto)
 294         struct interface_info *interface;
 295         struct packet *packet;
 296         struct dhcp_packet *raw;
 297         size_t len;
 298         struct in_addr from;
 299         struct sockaddr_in *to;
 300         struct hardware *hto;
 301 {
 302         unsigned bufp;
 303         unsigned char buf [1536 + sizeof (struct sockaddr)];
 304         struct sockaddr *junk;
 305         struct strbuf ctl, data;
 306         int hw_end;
 307         struct sockaddr_in foo;
 308         int result;
 309
 310         if (!strcmp (interface -> name, "fallback"))
 311                 return send_fallback (interface, packet, raw,
 312                                       len, from, to, hto);
 313
 314         /* Start with the sockaddr struct... */
 315         junk = (struct sockaddr *)&buf [0];
 316         bufp = ((unsigned char *)&junk -> sa_data [0]) - &buf [0];
 317
 318         /* Assemble the headers... */
 319         assemble_hw_header (interface, buf, &bufp, hto);
 320         hw_end = bufp;
 321         assemble_udp_ip_header (interface, buf, &bufp, from.s_addr,
 322                                 to -> sin_addr.s_addr, to -> sin_port,
 323                                 raw, len);
 324
 325         /* Copy the data into the buffer (yuk). */
 326         memcpy (buf + bufp, raw, len);
 327
 328         /* Set up the sockaddr structure... */
 329 #if USE_SIN_LEN
 330         junk -> sa_len = hw_end - 2; /* XXX */
 331 #endif
 332         junk -> sa_family = AF_UNSPEC;
 333
 334 #if 0 /* Already done. */
 335         memcpy (junk.sa_data, buf, hw_len);
 336 #endif
 337
 338         /* Set up the msg_buf structure... */
 339         ctl.buf = (char *)&buf [0];
 340         ctl.maxlen = ctl.len = hw_end;
 341         data.buf = (char *)&buf [hw_end];
 342         data.maxlen = data.len = bufp + len - hw_end;
 343
 344         result = putmsg (interface -> wfdesc, &ctl, &data, 0);
 345         if (result < 0)
 346                 log_error ("send_packet: %m");
 347         return result;
 348 }
 349 #endif /* USE_NIT_SEND */
 350
 351 #ifdef USE_NIT_RECEIVE
 352 ssize_t receive_packet (interface, buf, len, from, hfrom)
 353         struct interface_info *interface;
 354         unsigned char *buf;
 355         size_t len;
 356         struct sockaddr_in *from;
 357         struct hardware *hfrom;
 358 {
 359         int nread;
 360         int length = 0;
 361         int offset = 0;
 362         unsigned char ibuf [1536];
 363         int bufix = 0;
 364
 365         length = read (interface -> rfdesc, ibuf, sizeof ibuf);
 366         if (length <= 0)
 367                 return length;
 368
 369         /* Decode the physical header... */
 370         offset = decode_hw_header (interface, ibuf, bufix, hfrom);
 371
 372         /* If a physical layer checksum failed (dunno of any
 373            physical layer that supports this, but WTH), skip this
 374            packet. */
 375         if (offset < 0) {
 376                 return 0;
 377         }
 378
 379         bufix += offset;
 380         length -= offset;
 381
 382         /* Decode the IP and UDP headers... */
 383         offset = decode_udp_ip_header (interface, ibuf, bufix,
 384                                        from, (unsigned char *)0, length);
 385
 386         /* If the IP or UDP checksum was bad, skip the packet... */
 387         if (offset < 0)
 388                 return 0;
 389
 390         bufix += offset;
 391         length -= offset;
 392
 393         /* Copy out the data in the packet... */
 394         memcpy (buf, &ibuf [bufix], length);
 395         return length;
 396 }
 397
 398 int can_unicast_without_arp (ip)
 399         struct interface_info *ip;
 400 {
 401         return 1;
 402 }
 403
 404 int can_receive_unicast_unconfigured (ip)
 405         struct interface_info *ip;
 406 {
 407         return 1;
 408 }
 409
 410 void maybe_setup_fallback ()
 411 {
 412         isc_result_t status;
 413         struct interface_info *fbi;
 414         fbi = setup_fallback ();
 415         if (fbi) {
 416                 if_register_fallback (fbi);
 417                 fbi -> refcnt = 1;
 418                 fbi -> type = dhcp_type_interface;
 419                 status = omapi_register_io_object ((omapi_object_t *)fbi,
 420                                                    if_readsocket, 0,
 421                                                    fallback_discard, 0, 0);
 422                 if (status != ISC_R_SUCCESS)
 423                         log_fatal ("Can't register I/O handle for %s: %s",
 424                                    fbi -> name, isc_result_totext (status));
 425         }
 426 }
 427 #endif