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 #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
  47
  48 /* globals */
  49 struct dhcpOfferedAddr *leases;
  50 struct server_config_t server_config;
  51
  52
  53 int udhcpd_main(int argc, char *argv[])
  54 {
  55         fd_set rfds;
  56         struct timeval tv;
  57         int server_socket = -1;
  58         int bytes, retval;
  59         struct dhcpMessage packet;
  60         unsigned char *state;
  61         unsigned char *server_id, *requested;
  62         u_int32_t server_id_align, requested_align;
  63         unsigned long timeout_end;
  64         struct option_set *option;
  65         struct dhcpOfferedAddr *lease;
  66         int max_sock;
  67         int sig;
  68         unsigned long num_ips;
  69
  70         start_log("server");
  71
  72         memset(&server_config, 0, sizeof(struct server_config_t));
  73
  74         if (argc < 2)
  75                 read_config(DHCPD_CONF_FILE);
  76         else read_config(argv[1]);
  77
  78         if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) {
  79                 memcpy(&server_config.lease, option->data + 2, 4);
  80                 server_config.lease = ntohl(server_config.lease);
  81         }
  82         else server_config.lease = LEASE_TIME;
  83
  84         /* Sanity check */
  85         num_ips = ntohl(server_config.end) - ntohl(server_config.start);
  86         if (server_config.max_leases > num_ips) {
  87                 LOG(LOG_ERR, "max_leases value (%lu) not sane, "
  88                         "setting to %lu instead",
  89                         server_config.max_leases, num_ips);
  90                 server_config.max_leases = num_ips;
  91         }
  92
  93         leases = xcalloc(sizeof(struct dhcpOfferedAddr), server_config.max_leases);
  94         read_leases(server_config.lease_file);
  95
  96         if (read_interface(server_config.interface, &server_config.ifindex,
  97                            &server_config.server, server_config.arp) < 0)
  98                 return(1);
  99
 100 #ifndef CONFIG_FEATURE_UDHCP_DEBUG
 101         background(server_config.pidfile);
 102 #endif
 103
 104         udhcp_set_signal_pipe(0);
 105
 106         timeout_end = time(0) + server_config.auto_time;
 107         while(1) { /* loop until universe collapses */
 108
 109                 if (server_socket < 0)
 110                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
 111                                 LOG(LOG_ERR, "FATAL: couldn't create server socket, %m");
 112                                 return(2);
 113                         }
 114
 115                 FD_ZERO(&rfds);
 116                 FD_SET(server_socket, &rfds);
 117                 FD_SET(udhcp_signal_pipe[0], &rfds);
 118                 if (server_config.auto_time) {
 119                         tv.tv_sec = timeout_end - time(0);
 120                         tv.tv_usec = 0;
 121                 }
 122                 if (!server_config.auto_time || tv.tv_sec > 0) {
 123                         max_sock = server_socket > udhcp_signal_pipe[0] ? server_socket : udhcp_signal_pipe[0];
 124                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 125                                         server_config.auto_time ? &tv : NULL);
 126                 } else retval = 0; /* If we already timed out, fall through */
 127
 128                 if (retval == 0) {
 129                         write_leases();
 130                         timeout_end = time(0) + server_config.auto_time;
 131                         continue;
 132                 } else if (retval < 0 && errno != EINTR) {
 133                         DEBUG(LOG_INFO, "error on select");
 134                         continue;
 135                 }
 136
 137                 if (FD_ISSET(udhcp_signal_pipe[0], &rfds)) {
 138                         if (read(udhcp_signal_pipe[0], &sig, sizeof(sig)) < 0)
 139                                 continue; /* probably just EINTR */
 140                         switch (sig) {
 141                         case SIGUSR1:
 142                                 LOG(LOG_INFO, "Received a SIGUSR1");
 143                                 write_leases();
 144                                 /* why not just reset the timeout, eh */
 145                                 timeout_end = time(0) + server_config.auto_time;
 146                                 continue;
 147                         case SIGTERM:
 148                                 LOG(LOG_INFO, "Received a SIGTERM");
 149                                 return(0);
 150                         }
 151                 }
 152
 153                 if ((bytes = get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 154                         if (bytes == -1 && errno != EINTR) {
 155                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 156                                 close(server_socket);
 157                                 server_socket = -1;
 158                         }
 159                         continue;
 160                 }
 161
 162                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 163                         DEBUG(LOG_ERR, "couldn't get option from packet, ignoring");
 164                         continue;
 165                 }
 166
 167                 /* ADDME: look for a static lease */
 168                 lease = find_lease_by_chaddr(packet.chaddr);
 169                 switch (state[0]) {
 170                 case DHCPDISCOVER:
 171                         DEBUG(LOG_INFO,"received DISCOVER");
 172
 173                         if (sendOffer(&packet) < 0) {
 174                                 LOG(LOG_ERR, "send OFFER failed");
 175                         }
 176                         break;
 177                 case DHCPREQUEST:
 178                         DEBUG(LOG_INFO, "received REQUEST");
 179
 180                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 181                         server_id = get_option(&packet, DHCP_SERVER_ID);
 182
 183                         if (requested) memcpy(&requested_align, requested, 4);
 184                         if (server_id) memcpy(&server_id_align, server_id, 4);
 185
 186                         if (lease) { /*ADDME: or static lease */
 187                                 if (server_id) {
 188                                         /* SELECTING State */
 189                                         DEBUG(LOG_INFO, "server_id = %08x", ntohl(server_id_align));
 190                                         if (server_id_align == server_config.server && requested &&
 191                                             requested_align == lease->yiaddr) {
 192                                                 sendACK(&packet, lease->yiaddr);
 193                                         }
 194                                 } else {
 195                                         if (requested) {
 196                                                 /* INIT-REBOOT State */
 197                                                 if (lease->yiaddr == requested_align)
 198                                                         sendACK(&packet, lease->yiaddr);
 199                                                 else sendNAK(&packet);
 200                                         } else {
 201                                                 /* RENEWING or REBINDING State */
 202                                                 if (lease->yiaddr == packet.ciaddr)
 203                                                         sendACK(&packet, lease->yiaddr);
 204                                                 else {
 205                                                         /* don't know what to do!!!! */
 206                                                         sendNAK(&packet);
 207                                                 }
 208                                         }
 209                                 }
 210
 211                         /* what to do if we have no record of the client */
 212                         } else if (server_id) {
 213                                 /* SELECTING State */
 214
 215                         } else if (requested) {
 216                                 /* INIT-REBOOT State */
 217                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 218                                         if (lease_expired(lease)) {
 219                                                 /* probably best if we drop this lease */
 220                                                 memset(lease->chaddr, 0, 16);
 221                                         /* make some contention for this address */
 222                                         } else sendNAK(&packet);
 223                                 } else if (requested_align < server_config.start ||
 224                                            requested_align > server_config.end) {
 225                                         sendNAK(&packet);
 226                                 } /* else remain silent */
 227
 228                         } else {
 229                                  /* RENEWING or REBINDING State */
 230                         }
 231                         break;
 232                 case DHCPDECLINE:
 233                         DEBUG(LOG_INFO,"received DECLINE");
 234                         if (lease) {
 235                                 memset(lease->chaddr, 0, 16);
 236                                 lease->expires = time(0) + server_config.decline_time;
 237                         }
 238                         break;
 239                 case DHCPRELEASE:
 240                         DEBUG(LOG_INFO,"received RELEASE");
 241                         if (lease) lease->expires = time(0);
 242                         break;
 243                 case DHCPINFORM:
 244                         DEBUG(LOG_INFO,"received INFORM");
 245                         send_inform(&packet);
 246                         break;
 247                 default:
 248                         LOG(LOG_WARNING, "unsupported DHCP message (%02x) -- ignoring", state[0]);
 249                 }
 250         }
 251
 252         return 0;
 253 }