contrib/dhcp-3.0/common/socket.c

   1 /* socket.c
   2
   3    BSD socket interface code... */
   4
   5 /*
   6  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   7  * Copyright (c) 1995-2003 by Internet Software Consortium
   8  *
   9  * Permission to use, copy, modify, and distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  19  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  *
  21  *   Internet Systems Consortium, Inc.
  22  *   950 Charter Street
  23  *   Redwood City, CA 94063
  24  *   <info@isc.org>
  25  *   http://www.isc.org/
  26  *
  27  * This software has been written for Internet Systems Consortium
  28  * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
  29  * To learn more about Internet Systems Consortium, see
  30  * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
  31  * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
  32  * ``http://www.nominum.com''.
  33  */
  34
  35 /* SO_BINDTODEVICE support added by Elliot Poger (poger@leland.stanford.edu).
  36  * This sockopt allows a socket to be bound to a particular interface,
  37  * thus enabling the use of DHCPD on a multihomed host.
  38  * If SO_BINDTODEVICE is defined in your system header files, the use of
  39  * this sockopt will be automatically enabled.
  40  * I have implemented it under Linux; other systems should be doable also.
  41  */
  42
  43 #ifndef lint
  44 static char copyright[] =
  45 "$Id: socket.c,v 1.55.2.4 2004/06/10 17:59:21 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium.  All rights reserved.\n";
  46 #endif /* not lint */
  47
  48 #include "dhcpd.h"
  49
  50 #ifdef USE_SOCKET_FALLBACK
  51 # if !defined (USE_SOCKET_SEND)
  52 #  define if_register_send if_register_fallback
  53 #  define send_packet send_fallback
  54 #  define if_reinitialize_send if_reinitialize_fallback
  55 # endif
  56 #endif
  57
  58 static int once = 0;
  59
  60 /* Reinitializes the specified interface after an address change.   This
  61    is not required for packet-filter APIs. */
  62
  63 #if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
  64 void if_reinitialize_send (info)
  65         struct interface_info *info;
  66 {
  67 #if 0
  68 #ifndef USE_SOCKET_RECEIVE
  69         once = 0;
  70         close (info -> wfdesc);
  71 #endif
  72         if_register_send (info);
  73 #endif
  74 }
  75 #endif
  76
  77 #ifdef USE_SOCKET_RECEIVE
  78 void if_reinitialize_receive (info)
  79         struct interface_info *info;
  80 {
  81 #if 0
  82         once = 0;
  83         close (info -> rfdesc);
  84         if_register_receive (info);
  85 #endif
  86 }
  87 #endif
  88
  89 #if defined (USE_SOCKET_SEND) || \
  90         defined (USE_SOCKET_RECEIVE) || \
  91                 defined (USE_SOCKET_FALLBACK)
  92 /* Generic interface registration routine... */
  93 int if_register_socket (info)
  94         struct interface_info *info;
  95 {
  96         struct sockaddr_in name;
  97         int sock;
  98         int flag;
  99
 100 #if !defined (HAVE_SO_BINDTODEVICE) && !defined (USE_FALLBACK)
 101         /* Make sure only one interface is registered. */
 102         if (once)
 103                 log_fatal ("The standard socket API can only support %s",
 104                        "hosts with a single network interface.");
 105         once = 1;
 106 #endif
 107
 108         memset (&name, 0, sizeof (name));
 109         /* Set up the address we're going to bind to. */
 110         name.sin_family = AF_INET;
 111         name.sin_port = local_port;
 112         name.sin_addr = local_address;
 113
 114         /* Make a socket... */
 115         if ((sock = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
 116                 log_fatal ("Can't create dhcp socket: %m");
 117
 118         /* Set the REUSEADDR option so that we don't fail to start if
 119            we're being restarted. */
 120         flag = 1;
 121         if (setsockopt (sock, SOL_SOCKET, SO_REUSEADDR,
 122                         (char *)&flag, sizeof flag) < 0)
 123                 log_fatal ("Can't set SO_REUSEADDR option on dhcp socket: %m");
 124
 125         /* Set the BROADCAST option so that we can broadcast DHCP responses.
 126            We shouldn't do this for fallback devices, and we can detect that
 127            a device is a fallback because it has no ifp structure. */
 128         if (info -> ifp &&
 129             (setsockopt (sock, SOL_SOCKET, SO_BROADCAST,
 130                          (char *)&flag, sizeof flag) < 0))
 131                 log_fatal ("Can't set SO_BROADCAST option on dhcp socket: %m");
 132
 133         /* Bind the socket to this interface's IP address. */
 134         if (bind (sock, (struct sockaddr *)&name, sizeof name) < 0) {
 135                 log_error ("Can't bind to dhcp address: %m");
 136                 log_error ("Please make sure there is no other dhcp server");
 137                 log_error ("running and that there's no entry for dhcp or");
 138                 log_error ("bootp in /etc/inetd.conf.   Also make sure you");
 139                 log_error ("are not running HP JetAdmin software, which");
 140                 log_fatal ("includes a bootp server.");
 141         }
 142
 143 #if defined (HAVE_SO_BINDTODEVICE)
 144         /* Bind this socket to this interface. */
 145         if (info -> ifp &&
 146             setsockopt (sock, SOL_SOCKET, SO_BINDTODEVICE,
 147                         (char *)(info -> ifp), sizeof *(info -> ifp)) < 0) {
 148                 log_fatal ("setsockopt: SO_BINDTODEVICE: %m");
 149         }
 150 #endif
 151
 152         return sock;
 153 }
 154 #endif /* USE_SOCKET_SEND || USE_SOCKET_RECEIVE || USE_SOCKET_FALLBACK */
 155
 156 #if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
 157 void if_register_send (info)
 158         struct interface_info *info;
 159 {
 160 #ifndef USE_SOCKET_RECEIVE
 161         info -> wfdesc = if_register_socket (info);
 162 #if defined (USE_SOCKET_FALLBACK)
 163         /* Fallback only registers for send, but may need to receive as
 164            well. */
 165         info -> rfdesc = info -> wfdesc;
 166 #endif
 167 #else
 168         info -> wfdesc = info -> rfdesc;
 169 #endif
 170         if (!quiet_interface_discovery)
 171                 log_info ("Sending on   Socket/%s%s%s",
 172                       info -> name,
 173                       (info -> shared_network ? "/" : ""),
 174                       (info -> shared_network ?
 175                        info -> shared_network -> name : ""));
 176 }
 177
 178 #if defined (USE_SOCKET_SEND)
 179 void if_deregister_send (info)
 180         struct interface_info *info;
 181 {
 182 #ifndef USE_SOCKET_RECEIVE
 183         close (info -> wfdesc);
 184 #endif
 185         info -> wfdesc = -1;
 186
 187         if (!quiet_interface_discovery)
 188                 log_info ("Disabling output on Socket/%s%s%s",
 189                       info -> name,
 190                       (info -> shared_network ? "/" : ""),
 191                       (info -> shared_network ?
 192                        info -> shared_network -> name : ""));
 193 }
 194 #endif /* USE_SOCKET_SEND */
 195 #endif /* USE_SOCKET_SEND || USE_SOCKET_FALLBACK */
 196
 197 #ifdef USE_SOCKET_RECEIVE
 198 void if_register_receive (info)
 199         struct interface_info *info;
 200 {
 201         /* If we're using the socket API for sending and receiving,
 202            we don't need to register this interface twice. */
 203         info -> rfdesc = if_register_socket (info);
 204         if (!quiet_interface_discovery)
 205                 log_info ("Listening on Socket/%s%s%s",
 206                       info -> name,
 207                       (info -> shared_network ? "/" : ""),
 208                       (info -> shared_network ?
 209                        info -> shared_network -> name : ""));
 210 }
 211
 212 void if_deregister_receive (info)
 213         struct interface_info *info;
 214 {
 215         close (info -> rfdesc);
 216         info -> rfdesc = -1;
 217
 218         if (!quiet_interface_discovery)
 219                 log_info ("Disabling input on Socket/%s%s%s",
 220                       info -> name,
 221                       (info -> shared_network ? "/" : ""),
 222                       (info -> shared_network ?
 223                        info -> shared_network -> name : ""));
 224 }
 225 #endif /* USE_SOCKET_RECEIVE */
 226
 227 #if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
 228 ssize_t send_packet (interface, packet, raw, len, from, to, hto)
 229         struct interface_info *interface;
 230         struct packet *packet;
 231         struct dhcp_packet *raw;
 232         size_t len;
 233         struct in_addr from;
 234         struct sockaddr_in *to;
 235         struct hardware *hto;
 236 {
 237         int result;
 238 #ifdef IGNORE_HOSTUNREACH
 239         int retry = 0;
 240         do {
 241 #endif
 242                 result = sendto (interface -> wfdesc, (char *)raw, len, 0,
 243                                  (struct sockaddr *)to, sizeof *to);
 244 #ifdef IGNORE_HOSTUNREACH
 245         } while (to -> sin_addr.s_addr == htonl (INADDR_BROADCAST) &&
 246                  result < 0 &&
 247                  (errno == EHOSTUNREACH ||
 248                   errno == ECONNREFUSED) &&
 249                  retry++ < 10);
 250 #endif
 251         if (result < 0) {
 252                 log_error ("send_packet: %m");
 253                 if (errno == ENETUNREACH)
 254                         log_error ("send_packet: please consult README file%s",
 255                                    " regarding broadcast address.");
 256         }
 257         return result;
 258 }
 259 #endif /* USE_SOCKET_SEND || USE_SOCKET_FALLBACK */
 260
 261 #ifdef USE_SOCKET_RECEIVE
 262 ssize_t receive_packet (interface, buf, len, from, hfrom)
 263         struct interface_info *interface;
 264         unsigned char *buf;
 265         size_t len;
 266         struct sockaddr_in *from;
 267         struct hardware *hfrom;
 268 {
 269         SOCKLEN_T flen = sizeof *from;
 270         int result;
 271
 272 #ifdef IGNORE_HOSTUNREACH
 273         int retry = 0;
 274         do {
 275 #endif
 276                 result = recvfrom (interface -> rfdesc, (char *)buf, len, 0,
 277                                    (struct sockaddr *)from, &flen);
 278 #ifdef IGNORE_HOSTUNREACH
 279         } while (result < 0 &&
 280                  (errno == EHOSTUNREACH ||
 281                   errno == ECONNREFUSED) &&
 282                  retry++ < 10);
 283 #endif
 284         return result;
 285 }
 286 #endif /* USE_SOCKET_RECEIVE */
 287
 288 #if defined (USE_SOCKET_FALLBACK)
 289 /* This just reads in a packet and silently discards it. */
 290
 291 isc_result_t fallback_discard (object)
 292         omapi_object_t *object;
 293 {
 294         char buf [1540];
 295         struct sockaddr_in from;
 296         SOCKLEN_T flen = sizeof from;
 297         int status;
 298         struct interface_info *interface;
 299
 300         if (object -> type != dhcp_type_interface)
 301                 return ISC_R_INVALIDARG;
 302         interface = (struct interface_info *)object;
 303
 304         status = recvfrom (interface -> wfdesc, buf, sizeof buf, 0,
 305                            (struct sockaddr *)&from, &flen);
 306 #if defined (DEBUG)
 307         /* Only report fallback discard errors if we're debugging. */
 308         if (status < 0) {
 309                 log_error ("fallback_discard: %m");
 310                 return ISC_R_UNEXPECTED;
 311         }
 312 #endif
 313         return ISC_R_SUCCESS;
 314 }
 315 #endif /* USE_SOCKET_FALLBACK */
 316
 317 #if defined (USE_SOCKET_SEND)
 318 int can_unicast_without_arp (ip)
 319         struct interface_info *ip;
 320 {
 321         return 0;
 322 }
 323
 324 int can_receive_unicast_unconfigured (ip)
 325         struct interface_info *ip;
 326 {
 327 #if defined (SOCKET_CAN_RECEIVE_UNICAST_UNCONFIGURED)
 328         return 1;
 329 #else
 330         return 0;
 331 #endif
 332 }
 333
 334 int supports_multiple_interfaces (ip)
 335         struct interface_info *ip;
 336 {
 337 #if defined (SO_BINDTODEVICE)
 338         return 1;
 339 #else
 340         return 0;
 341 #endif
 342 }
 343
 344 /* If we have SO_BINDTODEVICE, set up a fallback interface; otherwise,
 345    do not. */
 346
 347 void maybe_setup_fallback ()
 348 {
 349 #if defined (USE_SOCKET_FALLBACK)
 350         isc_result_t status;
 351         struct interface_info *fbi = (struct interface_info *)0;
 352         if (setup_fallback (&fbi, MDL)) {
 353                 fbi -> wfdesc = if_register_socket (fbi);
 354                 fbi -> rfdesc = fbi -> wfdesc;
 355                 log_info ("Sending on   Socket/%s%s%s",
 356                       fbi -> name,
 357                       (fbi -> shared_network ? "/" : ""),
 358                       (fbi -> shared_network ?
 359                        fbi -> shared_network -> name : ""));
 360
 361                 status = omapi_register_io_object ((omapi_object_t *)fbi,
 362                                                    if_readsocket, 0,
 363                                                    fallback_discard, 0, 0);
 364                 if (status != ISC_R_SUCCESS)
 365                         log_fatal ("Can't register I/O handle for %s: %s",
 366                                    fbi -> name, isc_result_totext (status));
 367                 interface_dereference (&fbi, MDL);
 368         }
 369 #endif
 370 }
 371 #endif /* USE_SOCKET_SEND */