networking/udhcp/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
  38 #include "dhcpd.h"
  39 #include "arpping.h"
  40 #include "socket.h"
  41 #include "options.h"
  42 #include "files.h"
  43 #include "serverpacket.h"
  44 #include "common.h"
  45 #include "signalpipe.h"
  46 #include "static_leases.h"
  47
  48
  49 /* globals */
  50 struct dhcpOfferedAddr *leases;
  51 struct server_config_t server_config;
  52
  53
  54 int udhcpd_main(int argc, char *argv[])
  55 {
  56         fd_set rfds;
  57         struct timeval tv;
  58         int server_socket = -1, bytes, retval, max_sock;
  59         struct dhcpMessage packet;
  60         uint8_t *state, *server_id, *requested;
  61         uint32_t server_id_align, requested_align, static_lease_ip;
  62         unsigned long timeout_end, num_ips;
  63         struct option_set *option;
  64         struct dhcpOfferedAddr *lease, static_lease;
  65
  66         read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]);
  67
  68         /* Start the log, sanitize fd's, and write a pid file */
  69         start_log_and_pid("udhcpd", server_config.pidfile);
  70
  71         if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) {
  72                 memcpy(&server_config.lease, option->data + 2, 4);
  73                 server_config.lease = ntohl(server_config.lease);
  74         }
  75         else server_config.lease = LEASE_TIME;
  76
  77         /* Sanity check */
  78         num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1;
  79         if (server_config.max_leases > num_ips) {
  80                 LOG(LOG_ERR, "max_leases value (%lu) not sane, "
  81                         "setting to %lu instead",
  82                         server_config.max_leases, num_ips);
  83                 server_config.max_leases = num_ips;
  84         }
  85
  86         leases = xzalloc(server_config.max_leases * sizeof(struct dhcpOfferedAddr));
  87         read_leases(server_config.lease_file);
  88
  89         if (read_interface(server_config.interface, &server_config.ifindex,
  90                            &server_config.server, server_config.arp) < 0)
  91                 return 1;
  92
  93 #ifndef UDHCP_DEBUG
  94         background(server_config.pidfile); /* hold lock during fork. */
  95 #endif
  96
  97         /* Setup the signal pipe */
  98         udhcp_sp_setup();
  99
 100         timeout_end = time(0) + server_config.auto_time;
 101         while(1) { /* loop until universe collapses */
 102
 103                 if (server_socket < 0)
 104                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
 105                                 LOG(LOG_ERR, "FATAL: couldn't create server socket, %m");
 106                                 return 2;
 107                         }
 108
 109                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
 110                 if (server_config.auto_time) {
 111                         tv.tv_sec = timeout_end - time(0);
 112                         tv.tv_usec = 0;
 113                 }
 114                 if (!server_config.auto_time || tv.tv_sec > 0) {
 115                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 116                                         server_config.auto_time ? &tv : NULL);
 117                 } else retval = 0; /* If we already timed out, fall through */
 118
 119                 if (retval == 0) {
 120                         write_leases();
 121                         timeout_end = time(0) + server_config.auto_time;
 122                         continue;
 123                 } else if (retval < 0 && errno != EINTR) {
 124                         DEBUG(LOG_INFO, "error on select");
 125                         continue;
 126                 }
 127
 128                 switch (udhcp_sp_read(&rfds)) {
 129                 case SIGUSR1:
 130                         LOG(LOG_INFO, "Received a SIGUSR1");
 131                         write_leases();
 132                         /* why not just reset the timeout, eh */
 133                         timeout_end = time(0) + server_config.auto_time;
 134                         continue;
 135                 case SIGTERM:
 136                         LOG(LOG_INFO, "Received a SIGTERM");
 137                         return 0;
 138                 case 0: break;          /* no signal */
 139                 default: continue;      /* signal or error (probably EINTR) */
 140                 }
 141
 142                 if ((bytes = get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 143                         if (bytes == -1 && errno != EINTR) {
 144                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 145                                 close(server_socket);
 146                                 server_socket = -1;
 147                         }
 148                         continue;
 149                 }
 150
 151                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 152                         DEBUG(LOG_ERR, "couldn't get option from packet, ignoring");
 153                         continue;
 154                 }
 155
 156                 /* Look for a static lease */
 157                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 158
 159                 if(static_lease_ip)
 160                 {
 161                         printf("Found static lease: %x\n", static_lease_ip);
 162
 163                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 164                         static_lease.yiaddr = static_lease_ip;
 165                         static_lease.expires = 0;
 166
 167                         lease = &static_lease;
 168
 169                 }
 170                 else
 171                 {
 172                 lease = find_lease_by_chaddr(packet.chaddr);
 173                 }
 174
 175                 switch (state[0]) {
 176                 case DHCPDISCOVER:
 177                         DEBUG(LOG_INFO,"received DISCOVER");
 178
 179                         if (sendOffer(&packet) < 0) {
 180                                 LOG(LOG_ERR, "send OFFER failed");
 181                         }
 182                         break;
 183                 case DHCPREQUEST:
 184                         DEBUG(LOG_INFO, "received REQUEST");
 185
 186                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 187                         server_id = get_option(&packet, DHCP_SERVER_ID);
 188
 189                         if (requested) memcpy(&requested_align, requested, 4);
 190                         if (server_id) memcpy(&server_id_align, server_id, 4);
 191
 192                         if (lease) {
 193                                 if (server_id) {
 194                                         /* SELECTING State */
 195                                         DEBUG(LOG_INFO, "server_id = %08x", ntohl(server_id_align));
 196                                         if (server_id_align == server_config.server && requested &&
 197                                             requested_align == lease->yiaddr) {
 198                                                 sendACK(&packet, lease->yiaddr);
 199                                         }
 200                                 } else {
 201                                         if (requested) {
 202                                                 /* INIT-REBOOT State */
 203                                                 if (lease->yiaddr == requested_align)
 204                                                         sendACK(&packet, lease->yiaddr);
 205                                                 else sendNAK(&packet);
 206                                         } else {
 207                                                 /* RENEWING or REBINDING State */
 208                                                 if (lease->yiaddr == packet.ciaddr)
 209                                                         sendACK(&packet, lease->yiaddr);
 210                                                 else {
 211                                                         /* don't know what to do!!!! */
 212                                                         sendNAK(&packet);
 213                                                 }
 214                                         }
 215                                 }
 216
 217                         /* what to do if we have no record of the client */
 218                         } else if (server_id) {
 219                                 /* SELECTING State */
 220
 221                         } else if (requested) {
 222                                 /* INIT-REBOOT State */
 223                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 224                                         if (lease_expired(lease)) {
 225                                                 /* probably best if we drop this lease */
 226                                                 memset(lease->chaddr, 0, 16);
 227                                         /* make some contention for this address */
 228                                         } else sendNAK(&packet);
 229                                 } else if (requested_align < server_config.start ||
 230                                            requested_align > server_config.end) {
 231                                         sendNAK(&packet);
 232                                 } /* else remain silent */
 233
 234                         } else {
 235                                  /* RENEWING or REBINDING State */
 236                         }
 237                         break;
 238                 case DHCPDECLINE:
 239                         DEBUG(LOG_INFO,"received DECLINE");
 240                         if (lease) {
 241                                 memset(lease->chaddr, 0, 16);
 242                                 lease->expires = time(0) + server_config.decline_time;
 243                         }
 244                         break;
 245                 case DHCPRELEASE:
 246                         DEBUG(LOG_INFO,"received RELEASE");
 247                         if (lease) lease->expires = time(0);
 248                         break;
 249                 case DHCPINFORM:
 250                         DEBUG(LOG_INFO,"received INFORM");
 251                         send_inform(&packet);
 252                         break;
 253                 default:
 254                         LOG(LOG_WARNING, "unsupported DHCP message (%02x) -- ignoring", state[0]);
 255                 }
 256         }
 257
 258         return 0;
 259 }
 260