contrib/dhcp-3.0/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) 2004 by Internet Systems Consortium, Inc. ("ISC")
   8  * Copyright (c) 1996-2003 by Internet Software Consortium
   9  *
  10  * Permission to use, copy, modify, and distribute this software for any
  11  * purpose with or without fee is hereby granted, provided that the above
  12  * copyright notice and this permission notice appear in all copies.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  15  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  16  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  17  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  18  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  19  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  20  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  21  *
  22  *   Internet Systems Consortium, Inc.
  23  *   950 Charter Street
  24  *   Redwood City, CA 94063
  25  *   <info@isc.org>
  26  *   http://www.isc.org/
  27  *
  28  * This software has been written for Internet Systems Consortium
  29  * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
  30  * To learn more about Internet Systems Consortium, see
  31  * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
  32  * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
  33  * ``http://www.nominum.com''.
  34  */
  35
  36 #ifndef lint
  37 static char copyright[] =
  38 "$Id: nit.c,v 1.34.2.3 2004/11/24 17:39:15 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium.  All rights reserved.\n";
  39 #endif /* not lint */
  40
  41 #include "dhcpd.h"
  42 #if defined (USE_NIT_SEND) || defined (USE_NIT_RECEIVE)
  43 #include <sys/ioctl.h>
  44 #include <sys/uio.h>
  45
  46 #include <sys/time.h>
  47 #include <net/nit.h>
  48 #include <net/nit_if.h>
  49 #include <net/nit_pf.h>
  50 #include <net/nit_buf.h>
  51 #include <sys/stropts.h>
  52 #include <net/packetfilt.h>
  53
  54 #include <netinet/in_systm.h>
  55 #include "includes/netinet/ip.h"
  56 #include "includes/netinet/udp.h"
  57 #include "includes/netinet/if_ether.h"
  58
  59 /* Reinitializes the specified interface after an address change.   This
  60    is not required for packet-filter APIs. */
  61
  62 #ifdef USE_NIT_SEND
  63 void if_reinitialize_send (info)
  64         struct interface_info *info;
  65 {
  66 }
  67 #endif
  68
  69 #ifdef USE_NIT_RECEIVE
  70 void if_reinitialize_receive (info)
  71         struct interface_info *info;
  72 {
  73 }
  74 #endif
  75
  76 /* Called by get_interface_list for each interface that's discovered.
  77    Opens a packet filter for each interface and adds it to the select
  78    mask. */
  79
  80 int if_register_nit (info)
  81         struct interface_info *info;
  82 {
  83         int sock;
  84         char filename[50];
  85         struct ifreq ifr;
  86         struct strioctl sio;
  87
  88         /* Open a NIT device */
  89         sock = open ("/dev/nit", O_RDWR);
  90         if (sock < 0)
  91                 log_fatal ("Can't open NIT device for %s: %m", info -> name);
  92
  93         /* Set the NIT device to point at this interface. */
  94         sio.ic_cmd = NIOCBIND;
  95         sio.ic_len = sizeof *(info -> ifp);
  96         sio.ic_dp = (char *)(info -> ifp);
  97         sio.ic_timout = INFTIM;
  98         if (ioctl (sock, I_STR, &sio) < 0)
  99                 log_fatal ("Can't attach interface %s to nit device: %m",
 100                        info -> name);
 101
 102         /* Get the low-level address... */
 103         sio.ic_cmd = SIOCGIFADDR;
 104         sio.ic_len = sizeof ifr;
 105         sio.ic_dp = (char *)&ifr;
 106         sio.ic_timout = INFTIM;
 107         if (ioctl (sock, I_STR, &sio) < 0)
 108                 log_fatal ("Can't get physical layer address for %s: %m",
 109                        info -> name);
 110
 111         /* XXX code below assumes ethernet interface! */
 112         info -> hw_address.hlen = 7;
 113         info -> hw_address.hbuf [0] = ARPHRD_ETHER;
 114         memcpy (&info -> hw_address.hbuf [1],
 115                 ifr.ifr_ifru.ifru_addr.sa_data, 6);
 116
 117         if (ioctl (sock, I_PUSH, "pf") < 0)
 118                 log_fatal ("Can't push packet filter onto NIT for %s: %m",
 119                        info -> name);
 120
 121         return sock;
 122 }
 123 #endif /* USE_NIT_SEND || USE_NIT_RECEIVE */
 124
 125 #ifdef USE_NIT_SEND
 126 void if_register_send (info)
 127         struct interface_info *info;
 128 {
 129         /* If we're using the nit API for sending and receiving,
 130            we don't need to register this interface twice. */
 131 #ifndef USE_NIT_RECEIVE
 132         struct packetfilt pf;
 133         struct strioctl sio;
 134
 135         info -> wfdesc = if_register_nit (info);
 136
 137         pf.Pf_Priority = 0;
 138         pf.Pf_FilterLen = 1;
 139         pf.Pf_Filter [0] = ENF_PUSHZERO;
 140
 141         /* Set up an NIT filter that rejects everything... */
 142         sio.ic_cmd = NIOCSETF;
 143         sio.ic_len = sizeof pf;
 144         sio.ic_dp = (char *)&pf;
 145         sio.ic_timout = INFTIM;
 146         if (ioctl (info -> wfdesc, I_STR, &sio) < 0)
 147                 log_fatal ("Can't set NIT filter: %m");
 148 #else
 149         info -> wfdesc = info -> rfdesc;
 150 #endif
 151         if (!quiet_interface_discovery)
 152                 log_info ("Sending on   NIT/%s%s%s",
 153                       print_hw_addr (info -> hw_address.hbuf [0],
 154                                      info -> hw_address.hlen - 1,
 155                                      &info -> hw_address.hbuf [1]),
 156                       (info -> shared_network ? "/" : ""),
 157                       (info -> shared_network ?
 158                        info -> shared_network -> name : ""));
 159 }
 160
 161 void if_deregister_send (info)
 162         struct interface_info *info;
 163 {
 164         /* If we're using the nit API for sending and receiving,
 165            we don't need to register this interface twice. */
 166 #ifndef USE_NIT_RECEIVE
 167         close (info -> wfdesc);
 168 #endif
 169         info -> wfdesc = -1;
 170         if (!quiet_interface_discovery)
 171                 log_info ("Disabling output on NIT/%s%s%s",
 172                       print_hw_addr (info -> hw_address.hbuf [0],
 173                                      info -> hw_address.hlen - 1,
 174                                      &info -> hw_address.hbuf [1]),
 175                       (info -> shared_network ? "/" : ""),
 176                       (info -> shared_network ?
 177                        info -> shared_network -> name : ""));
 178 }
 179 #endif /* USE_NIT_SEND */
 180
 181 #ifdef USE_NIT_RECEIVE
 182 /* Packet filter program...
 183    XXX Changes to the filter program may require changes to the constant
 184    offsets used in if_register_send to patch the NIT program! XXX */
 185
 186 void if_register_receive (info)
 187         struct interface_info *info;
 188 {
 189         int flag = 1;
 190         u_int32_t x;
 191         struct packetfilt pf;
 192         struct strioctl sio;
 193         u_int16_t addr [2];
 194         struct timeval t;
 195
 196         /* Open a NIT device and hang it on this interface... */
 197         info -> rfdesc = if_register_nit (info);
 198
 199         /* Set the snap length to 0, which means always take the whole
 200            packet. */
 201         x = 0;
 202         if (ioctl (info -> rfdesc, NIOCSSNAP, &x) < 0)
 203                 log_fatal ("Can't set NIT snap length on %s: %m", info -> name);
 204
 205         /* Set the stream to byte stream mode */
 206         if (ioctl (info -> rfdesc, I_SRDOPT, RMSGN) != 0)
 207                 log_info ("I_SRDOPT failed on %s: %m", info -> name);
 208
 209 #if 0
 210         /* Push on the chunker... */
 211         if (ioctl (info -> rfdesc, I_PUSH, "nbuf") < 0)
 212                 log_fatal ("Can't push chunker onto NIT STREAM: %m");
 213
 214         /* Set the timeout to zero. */
 215         t.tv_sec = 0;
 216         t.tv_usec = 0;
 217         if (ioctl (info -> rfdesc, NIOCSTIME, &t) < 0)
 218                 log_fatal ("Can't set chunk timeout: %m");
 219 #endif
 220
 221         /* Ask for no header... */
 222         x = 0;
 223         if (ioctl (info -> rfdesc, NIOCSFLAGS, &x) < 0)
 224                 log_fatal ("Can't set NIT flags on %s: %m", info -> name);
 225
 226         /* Set up the NIT filter program. */
 227         /* XXX Unlike the BPF filter program, this one won't work if the
 228            XXX IP packet is fragmented or if there are options on the IP
 229            XXX header. */
 230         pf.Pf_Priority = 0;
 231         pf.Pf_FilterLen = 0;
 232
 233         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 6;
 234         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND;
 235         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (ETHERTYPE_IP);
 236         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT;
 237         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (IPPROTO_UDP);
 238         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 11;
 239         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_AND;
 240         pf.Pf_Filter [pf.Pf_FilterLen++] = htons (0xFF);
 241         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_CAND;
 242         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 18;
 243         pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND;
 244         pf.Pf_Filter [pf.Pf_FilterLen++] = local_port;
 245
 246         /* Install the filter... */
 247         sio.ic_cmd = NIOCSETF;
 248         sio.ic_len = sizeof pf;
 249         sio.ic_dp = (char *)&pf;
 250         sio.ic_timout = INFTIM;
 251         if (ioctl (info -> rfdesc, I_STR, &sio) < 0)
 252                 log_fatal ("Can't set NIT filter on %s: %m", info -> name);
 253
 254         if (!quiet_interface_discovery)
 255                 log_info ("Listening on NIT/%s%s%s",
 256                       print_hw_addr (info -> hw_address.hbuf [0],
 257                                      info -> hw_address.hlen - 1,
 258                                      &info -> hw_address.hbuf [1]),
 259                       (info -> shared_network ? "/" : ""),
 260                       (info -> shared_network ?
 261                        info -> shared_network -> name : ""));
 262 }
 263
 264 void if_deregister_receive (info)
 265         struct interface_info *info;
 266 {
 267         /* If we're using the nit API for sending and receiving,
 268            we don't need to register this interface twice. */
 269         close (info -> rfdesc);
 270         info -> rfdesc = -1;
 271
 272         if (!quiet_interface_discovery)
 273                 log_info ("Disabling input on NIT/%s%s%s",
 274                       print_hw_addr (info -> hw_address.hbuf [0],
 275                                      info -> hw_address.hlen - 1,
 276                                      &info -> hw_address.hbuf [1]),
 277                       (info -> shared_network ? "/" : ""),
 278                       (info -> shared_network ?
 279                        info -> shared_network -> name : ""));
 280 }
 281 #endif /* USE_NIT_RECEIVE */
 282
 283 #ifdef USE_NIT_SEND
 284 ssize_t send_packet (interface, packet, raw, len, from, to, hto)
 285         struct interface_info *interface;
 286         struct packet *packet;
 287         struct dhcp_packet *raw;
 288         size_t len;
 289         struct in_addr from;
 290         struct sockaddr_in *to;
 291         struct hardware *hto;
 292 {
 293         unsigned hbufp, ibufp;
 294         double hh [16];
 295         double ih [1536 / sizeof (double)];
 296         unsigned char *buf = (unsigned char *)ih;
 297         struct sockaddr *junk;
 298         struct strbuf ctl, data;
 299         struct sockaddr_in foo;
 300         int result;
 301
 302         if (!strcmp (interface -> name, "fallback"))
 303                 return send_fallback (interface, packet, raw,
 304                                       len, from, to, hto);
 305
 306         /* Start with the sockaddr struct... */
 307         junk = (struct sockaddr *)&hh [0];
 308         hbufp = (((unsigned char *)&junk -> sa_data [0]) -
 309                  (unsigned char *)&hh[0]);
 310         ibufp = 0;
 311
 312         /* Assemble the headers... */
 313         assemble_hw_header (interface, (unsigned char *)junk, &hbufp, hto);
 314         assemble_udp_ip_header (interface, buf, &ibufp,
 315                                 from.s_addr, to -> sin_addr.s_addr,
 316                                 to -> sin_port, (unsigned char *)raw, len);
 317
 318         /* Copy the data into the buffer (yuk). */
 319         memcpy (buf + ibufp, raw, len);
 320
 321         /* Set up the sockaddr structure... */
 322 #if USE_SIN_LEN
 323         junk -> sa_len = hbufp - 2; /* XXX */
 324 #endif
 325         junk -> sa_family = AF_UNSPEC;
 326
 327         /* Set up the msg_buf structure... */
 328         ctl.buf = (char *)&hh [0];
 329         ctl.maxlen = ctl.len = hbufp;
 330         data.buf = (char *)&ih [0];
 331         data.maxlen = data.len = ibufp + len;
 332
 333         result = putmsg (interface -> wfdesc, &ctl, &data, 0);
 334         if (result < 0)
 335                 log_error ("send_packet: %m");
 336         return result;
 337 }
 338 #endif /* USE_NIT_SEND */
 339
 340 #ifdef USE_NIT_RECEIVE
 341 ssize_t receive_packet (interface, buf, len, from, hfrom)
 342         struct interface_info *interface;
 343         unsigned char *buf;
 344         size_t len;
 345         struct sockaddr_in *from;
 346         struct hardware *hfrom;
 347 {
 348         int nread;
 349         int length = 0;
 350         int offset = 0;
 351         unsigned char ibuf [1536];
 352         int bufix = 0;
 353
 354         length = read (interface -> rfdesc, ibuf, sizeof ibuf);
 355         if (length <= 0)
 356                 return length;
 357
 358         /* Decode the physical header... */
 359         offset = decode_hw_header (interface, ibuf, bufix, hfrom);
 360
 361         /* If a physical layer checksum failed (dunno of any
 362            physical layer that supports this, but WTH), skip this
 363            packet. */
 364         if (offset < 0) {
 365                 return 0;
 366         }
 367
 368         bufix += offset;
 369         length -= offset;
 370
 371         /* Decode the IP and UDP headers... */
 372         offset = decode_udp_ip_header (interface, ibuf, bufix,
 373                                        from, length);
 374
 375         /* If the IP or UDP checksum was bad, skip the packet... */
 376         if (offset < 0)
 377                 return 0;
 378
 379         bufix += offset;
 380         length -= offset;
 381
 382         /* Copy out the data in the packet... */
 383         memcpy (buf, &ibuf [bufix], length);
 384         return length;
 385 }
 386
 387 int can_unicast_without_arp (ip)
 388         struct interface_info *ip;
 389 {
 390         return 1;
 391 }
 392
 393 int can_receive_unicast_unconfigured (ip)
 394         struct interface_info *ip;
 395 {
 396         return 1;
 397 }
 398
 399 int supports_multiple_interfaces (ip)
 400         struct interface_info *ip;
 401 {
 402         return 1;
 403 }
 404
 405 void maybe_setup_fallback ()
 406 {
 407         isc_result_t status;
 408         struct interface_info *fbi = (struct interface_info *)0;
 409         if (setup_fallback (&fbi, MDL)) {
 410                 if_register_fallback (fbi);
 411                 status = omapi_register_io_object ((omapi_object_t *)fbi,
 412                                                    if_readsocket, 0,
 413                                                    fallback_discard, 0, 0);
 414                 if (status != ISC_R_SUCCESS)
 415                         log_fatal ("Can't register I/O handle for %s: %s",
 416                                    fbi -> name, isc_result_totext (status));
 417                 interface_dereference (&fbi, MDL);
 418         }
 419 }
 420 #endif