git.maemo.org Git - udhcp/blob - dhcpd.c

   1 /* dhcpd.c
   2  *
   3  * udhcp Server
   4  * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
   5  *                      Chris Trew <ctrew@moreton.com.au>
   6  *
   7  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #include <fcntl.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27 #include <sys/wait.h>
  28 #include <arpa/inet.h>
  29 #include <netdb.h>
  30 #include <netinet/in.h>
  31 #include <sys/socket.h>
  32 #include <unistd.h>
  33 #include <signal.h>
  34 #include <errno.h>
  35 #include <sys/ioctl.h>
  36 #include <time.h>
  37 #include <sys/time.h>
  38
  39 #include "dhcpd.h"
  40 #include "arpping.h"
  41 #include "socket.h"
  42 #include "options.h"
  43 #include "files.h"
  44 #include "serverpacket.h"
  45 #include "common.h"
  46 #include "signalpipe.h"
  47 #include "static_leases.h"
  48
  49
  50 /* globals */
  51 struct dhcpOfferedAddr *leases;
  52 struct server_config_t server_config;
  53
  54
  55 #ifdef COMBINED_BINARY
  56 int udhcpd_main(int argc, char *argv[])
  57 #else
  58 int main(int argc, char *argv[])
  59 #endif
  60 {
  61         fd_set rfds;
  62         struct timeval tv;
  63         int server_socket = -1;
  64         int bytes, retval;
  65         struct dhcpMessage packet;
  66         uint8_t *state;
  67         uint8_t *server_id, *requested;
  68         uint32_t server_id_align, requested_align;
  69         unsigned long timeout_end;
  70         struct option_set *option;
  71         struct dhcpOfferedAddr *lease;
  72         struct dhcpOfferedAddr static_lease;
  73         int max_sock;
  74         unsigned long num_ips;
  75
  76         uint32_t static_lease_ip;
  77
  78         memset(&server_config, 0, sizeof(struct server_config_t));
  79         read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]);
  80
  81         /* Start the log, sanitize fd's, and write a pid file */
  82         start_log_and_pid("udhcpd", server_config.pidfile);
  83
  84         if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) {
  85                 memcpy(&server_config.lease, option->data + 2, 4);
  86                 server_config.lease = ntohl(server_config.lease);
  87         }
  88         else server_config.lease = LEASE_TIME;
  89
  90         /* Sanity check */
  91         // Let's try to fix http://bugs.debian.org/341139 (ericvb@debian.org - 16/12/05)
  92         //num_ips = ntohl(server_config.end) - ntohl(server_config.start);
  93         num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1;
  94         if (server_config.max_leases > num_ips) {
  95                 LOG(LOG_ERR, "max_leases value (%lu) not sane, "
  96                         "setting to %lu instead",
  97                         server_config.max_leases, num_ips);
  98                 server_config.max_leases = num_ips;
  99         }
 100
 101         leases = xcalloc(server_config.max_leases, sizeof(struct dhcpOfferedAddr));
 102         read_leases(server_config.lease_file);
 103
 104         if (read_interface(server_config.interface, &server_config.ifindex,
 105                            &server_config.server, server_config.arp) < 0)
 106                 return 1;
 107
 108 #ifndef UDHCP_DEBUG
 109         background(server_config.pidfile); /* hold lock during fork. */
 110 #endif
 111
 112         /* Setup the signal pipe */
 113         udhcp_sp_setup();
 114
 115         timeout_end = time(0) + server_config.auto_time;
 116         while(1) { /* loop until universe collapses */
 117
 118                 if (server_socket < 0)
 119                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
 120                                 LOG(LOG_ERR, "FATAL: couldn't create server socket, %m");
 121                                 return 2;
 122                         }
 123
 124                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
 125                 if (server_config.auto_time) {
 126                         tv.tv_sec = timeout_end - time(0);
 127                         tv.tv_usec = 0;
 128                 }
 129                 if (!server_config.auto_time || tv.tv_sec > 0) {
 130                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 131                                         server_config.auto_time ? &tv : NULL);
 132                 } else retval = 0; /* If we already timed out, fall through */
 133
 134                 if (retval == 0) {
 135                         write_leases();
 136                         timeout_end = time(0) + server_config.auto_time;
 137                         continue;
 138                 } else if (retval < 0 && errno != EINTR) {
 139                         DEBUG(LOG_INFO, "error on select");
 140                         continue;
 141                 }
 142
 143                 switch (udhcp_sp_read(&rfds)) {
 144                 case SIGUSR1:
 145                         LOG(LOG_INFO, "Received a SIGUSR1");
 146                         write_leases();
 147                         /* why not just reset the timeout, eh */
 148                         timeout_end = time(0) + server_config.auto_time;
 149                         continue;
 150                 case SIGTERM:
 151                         LOG(LOG_INFO, "Received a SIGTERM");
 152                         return 0;
 153                 case 0: break;          /* no signal */
 154                 default: continue;      /* signal or error (probably EINTR) */
 155                 }
 156
 157                 if ((bytes = get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 158                         if (bytes == -1 && errno != EINTR) {
 159                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 160                                 close(server_socket);
 161                                 server_socket = -1;
 162                         }
 163                         continue;
 164                 }
 165
 166                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 167                         DEBUG(LOG_ERR, "couldn't get option from packet, ignoring");
 168                         continue;
 169                 }
 170
 171                 /* Look for a static lease */
 172                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 173
 174                 if(static_lease_ip)
 175                 {
 176                         printf("Found static lease: %x\n", static_lease_ip);
 177
 178                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 179                         static_lease.yiaddr = static_lease_ip;
 180                         static_lease.expires = 0;
 181
 182                         lease = &static_lease;
 183
 184                 }
 185                 else
 186                 {
 187                 lease = find_lease_by_chaddr(packet.chaddr);
 188                 }
 189
 190                 switch (state[0]) {
 191                 case DHCPDISCOVER:
 192                         DEBUG(LOG_INFO,"received DISCOVER");
 193
 194                         if (sendOffer(&packet) < 0) {
 195                                 LOG(LOG_ERR, "send OFFER failed");
 196                         }
 197                         break;
 198                 case DHCPREQUEST:
 199                         DEBUG(LOG_INFO, "received REQUEST");
 200
 201                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 202                         server_id = get_option(&packet, DHCP_SERVER_ID);
 203
 204                         if (requested) memcpy(&requested_align, requested, 4);
 205                         if (server_id) memcpy(&server_id_align, server_id, 4);
 206
 207                         if (lease) {
 208                                 if (server_id) {
 209                                         /* SELECTING State */
 210                                         DEBUG(LOG_INFO, "server_id = %08x", ntohl(server_id_align));
 211                                         if (server_id_align == server_config.server && requested &&
 212                                             requested_align == lease->yiaddr) {
 213                                                 sendACK(&packet, lease->yiaddr);
 214                                         }
 215                                 } else {
 216                                         if (requested) {
 217                                                 /* INIT-REBOOT State */
 218                                                 if (lease->yiaddr == requested_align)
 219                                                         sendACK(&packet, lease->yiaddr);
 220                                                 else sendNAK(&packet);
 221                                         } else {
 222                                                 /* RENEWING or REBINDING State */
 223                                                 if (lease->yiaddr == packet.ciaddr)
 224                                                         sendACK(&packet, lease->yiaddr);
 225                                                 else {
 226                                                         /* don't know what to do!!!! */
 227                                                         sendNAK(&packet);
 228                                                 }
 229                                         }
 230                                 }
 231
 232                         /* what to do if we have no record of the client */
 233                         } else if (server_id) {
 234                                 /* SELECTING State */
 235
 236                         } else if (requested) {
 237                                 /* INIT-REBOOT State */
 238                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 239                                         if (lease_expired(lease)) {
 240                                                 /* probably best if we drop this lease */
 241                                                 memset(lease->chaddr, 0, 16);
 242                                         /* make some contention for this address */
 243                                         } else sendNAK(&packet);
 244                                 } else if (requested_align < server_config.start ||
 245                                            requested_align > server_config.end) {
 246                                         sendNAK(&packet);
 247                                 } /* else remain silent */
 248
 249                         } else {
 250                                  /* RENEWING or REBINDING State */
 251                         }
 252                         break;
 253                 case DHCPDECLINE:
 254                         DEBUG(LOG_INFO,"received DECLINE");
 255                         if (lease) {
 256                                 memset(lease->chaddr, 0, 16);
 257                                 lease->expires = time(0) + server_config.decline_time;
 258                         }
 259                         break;
 260                 case DHCPRELEASE:
 261                         DEBUG(LOG_INFO,"received RELEASE");
 262                         if (lease) lease->expires = time(0);
 263                         break;
 264                 case DHCPINFORM:
 265                         DEBUG(LOG_INFO,"received INFORM");
 266                         send_inform(&packet);
 267                         break;
 268                 default:
 269                         LOG(LOG_WARNING, "unsupported DHCP message (%02x) -- ignoring", state[0]);
 270                 }
 271         }
 272
 273         return 0;
 274 }
 275