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