busybox/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 #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         num_ips = ntohl(server_config.end) - ntohl(server_config.start);
  92         if (server_config.max_leases > num_ips) {
  93                 LOG(LOG_ERR, "max_leases value (%lu) not sane, "
  94                         "setting to %lu instead",
  95                         server_config.max_leases, num_ips);
  96                 server_config.max_leases = num_ips;
  97         }
  98
  99         leases = xcalloc(server_config.max_leases, sizeof(struct dhcpOfferedAddr));
 100         read_leases(server_config.lease_file);
 101
 102         if (read_interface(server_config.interface, &server_config.ifindex,
 103                            &server_config.server, server_config.arp) < 0)
 104                 return 1;
 105
 106 #ifndef UDHCP_DEBUG
 107         background(server_config.pidfile); /* hold lock during fork. */
 108 #endif
 109
 110         /* Setup the signal pipe */
 111         udhcp_sp_setup();
 112
 113         timeout_end = time(0) + server_config.auto_time;
 114         while(1) { /* loop until universe collapses */
 115
 116                 if (server_socket < 0)
 117                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
 118                                 LOG(LOG_ERR, "FATAL: couldn't create server socket, %m");
 119                                 return 2;
 120                         }
 121
 122                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
 123                 if (server_config.auto_time) {
 124                         tv.tv_sec = timeout_end - time(0);
 125                         tv.tv_usec = 0;
 126                 }
 127                 if (!server_config.auto_time || tv.tv_sec > 0) {
 128                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 129                                         server_config.auto_time ? &tv : NULL);
 130                 } else retval = 0; /* If we already timed out, fall through */
 131
 132                 if (retval == 0) {
 133                         write_leases();
 134                         timeout_end = time(0) + server_config.auto_time;
 135                         continue;
 136                 } else if (retval < 0 && errno != EINTR) {
 137                         DEBUG(LOG_INFO, "error on select");
 138                         continue;
 139                 }
 140
 141                 switch (udhcp_sp_read(&rfds)) {
 142                 case SIGUSR1:
 143                         LOG(LOG_INFO, "Received a SIGUSR1");
 144                         write_leases();
 145                         /* why not just reset the timeout, eh */
 146                         timeout_end = time(0) + server_config.auto_time;
 147                         continue;
 148                 case SIGTERM:
 149                         LOG(LOG_INFO, "Received a SIGTERM");
 150                         return 0;
 151                 case 0: break;          /* no signal */
 152                 default: continue;      /* signal or error (probably EINTR) */
 153                 }
 154
 155                 if ((bytes = get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 156                         if (bytes == -1 && errno != EINTR) {
 157                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 158                                 close(server_socket);
 159                                 server_socket = -1;
 160                         }
 161                         continue;
 162                 }
 163
 164                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 165                         DEBUG(LOG_ERR, "couldn't get option from packet, ignoring");
 166                         continue;
 167                 }
 168
 169                 /* Look for a static lease */
 170                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 171
 172                 if(static_lease_ip)
 173                 {
 174                         printf("Found static lease: %x\n", static_lease_ip);
 175
 176                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 177                         static_lease.yiaddr = static_lease_ip;
 178                         static_lease.expires = 0;
 179
 180                         lease = &static_lease;
 181
 182                 }
 183                 else
 184                 {
 185                 lease = find_lease_by_chaddr(packet.chaddr);
 186                 }
 187
 188                 switch (state[0]) {
 189                 case DHCPDISCOVER:
 190                         DEBUG(LOG_INFO,"received DISCOVER");
 191
 192                         if (sendOffer(&packet) < 0) {
 193                                 LOG(LOG_ERR, "send OFFER failed");
 194                         }
 195                         break;
 196                 case DHCPREQUEST:
 197                         DEBUG(LOG_INFO, "received REQUEST");
 198
 199                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 200                         server_id = get_option(&packet, DHCP_SERVER_ID);
 201
 202                         if (requested) memcpy(&requested_align, requested, 4);
 203                         if (server_id) memcpy(&server_id_align, server_id, 4);
 204
 205                         if (lease) {
 206                                 if (server_id) {
 207                                         /* SELECTING State */
 208                                         DEBUG(LOG_INFO, "server_id = %08x", ntohl(server_id_align));
 209                                         if (server_id_align == server_config.server && requested &&
 210                                             requested_align == lease->yiaddr) {
 211                                                 sendACK(&packet, lease->yiaddr);
 212                                         }
 213                                 } else {
 214                                         if (requested) {
 215                                                 /* INIT-REBOOT State */
 216                                                 if (lease->yiaddr == requested_align)
 217                                                         sendACK(&packet, lease->yiaddr);
 218                                                 else sendNAK(&packet);
 219                                         } else {
 220                                                 /* RENEWING or REBINDING State */
 221                                                 if (lease->yiaddr == packet.ciaddr)
 222                                                         sendACK(&packet, lease->yiaddr);
 223                                                 else {
 224                                                         /* don't know what to do!!!! */
 225                                                         sendNAK(&packet);
 226                                                 }
 227                                         }
 228                                 }
 229
 230                         /* what to do if we have no record of the client */
 231                         } else if (server_id) {
 232                                 /* SELECTING State */
 233
 234                         } else if (requested) {
 235                                 /* INIT-REBOOT State */
 236                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 237                                         if (lease_expired(lease)) {
 238                                                 /* probably best if we drop this lease */
 239                                                 memset(lease->chaddr, 0, 16);
 240                                         /* make some contention for this address */
 241                                         } else sendNAK(&packet);
 242                                 } else if (requested_align < server_config.start ||
 243                                            requested_align > server_config.end) {
 244                                         sendNAK(&packet);
 245                                 } /* else remain silent */
 246
 247                         } else {
 248                                  /* RENEWING or REBINDING State */
 249                         }
 250                         break;
 251                 case DHCPDECLINE:
 252                         DEBUG(LOG_INFO,"received DECLINE");
 253                         if (lease) {
 254                                 memset(lease->chaddr, 0, 16);
 255                                 lease->expires = time(0) + server_config.decline_time;
 256                         }
 257                         break;
 258                 case DHCPRELEASE:
 259                         DEBUG(LOG_INFO,"received RELEASE");
 260                         if (lease) lease->expires = time(0);
 261                         break;
 262                 case DHCPINFORM:
 263                         DEBUG(LOG_INFO,"received INFORM");
 264                         send_inform(&packet);
 265                         break;
 266                 default:
 267                         LOG(LOG_WARNING, "unsupported DHCP message (%02x) -- ignoring", state[0]);
 268                 }
 269         }
 270
 271         return 0;
 272 }
 273