networking/udhcp/dhcpd.c

   1 /* vi: set sw=4 ts=4: */
   2 /* dhcpd.c
   3  *
   4  * udhcp Server
   5  * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
   6  *                      Chris Trew <ctrew@moreton.com.au>
   7  *
   8  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   9  *
  10  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  11  */
  12
  13 #include "common.h"
  14 #include "dhcpd.h"
  15 #include "options.h"
  16
  17
  18 /* globals */
  19 struct dhcpOfferedAddr *leases;
  20 struct server_config_t server_config;
  21
  22
  23 int udhcpd_main(int argc, char *argv[])
  24 {
  25         fd_set rfds;
  26         struct timeval tv;
  27         int server_socket = -1, bytes, retval, max_sock;
  28         struct dhcpMessage packet;
  29         uint8_t *state, *server_id, *requested;
  30         uint32_t server_id_align, requested_align, static_lease_ip;
  31         unsigned long timeout_end, num_ips;
  32         struct option_set *option;
  33         struct dhcpOfferedAddr *lease, static_lease;
  34
  35         read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]);
  36
  37         /* Start the log, sanitize fd's, and write a pid file */
  38         udhcp_start_log_and_pid(server_config.pidfile);
  39
  40         if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) {
  41                 memcpy(&server_config.lease, option->data + 2, 4);
  42                 server_config.lease = ntohl(server_config.lease);
  43         }
  44         else server_config.lease = LEASE_TIME;
  45
  46         /* Sanity check */
  47         num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1;
  48         if (server_config.max_leases > num_ips) {
  49                 bb_error_msg("max_leases value (%lu) not sane, "
  50                         "setting to %lu instead",
  51                         server_config.max_leases, num_ips);
  52                 server_config.max_leases = num_ips;
  53         }
  54
  55         leases = xzalloc(server_config.max_leases * sizeof(struct dhcpOfferedAddr));
  56         read_leases(server_config.lease_file);
  57
  58         if (read_interface(server_config.interface, &server_config.ifindex,
  59                            &server_config.server, server_config.arp) < 0)
  60                 return 1;
  61
  62         if (!ENABLE_FEATURE_UDHCP_DEBUG)
  63                 udhcp_background(server_config.pidfile); /* hold lock during fork. */
  64
  65         /* Setup the signal pipe */
  66         udhcp_sp_setup();
  67
  68         timeout_end = time(0) + server_config.auto_time;
  69         while (1) { /* loop until universe collapses */
  70
  71                 if (server_socket < 0) {
  72                         server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface);
  73                         if (server_socket < 0) {
  74                                 bb_perror_msg("FATAL: cannot create server socket");
  75                                 return 2;
  76                         }
  77                 }
  78
  79                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
  80                 if (server_config.auto_time) {
  81                         tv.tv_sec = timeout_end - time(0);
  82                         tv.tv_usec = 0;
  83                 }
  84                 if (!server_config.auto_time || tv.tv_sec > 0) {
  85                         retval = select(max_sock + 1, &rfds, NULL, NULL,
  86                                         server_config.auto_time ? &tv : NULL);
  87                 } else retval = 0; /* If we already timed out, fall through */
  88
  89                 if (retval == 0) {
  90                         write_leases();
  91                         timeout_end = time(0) + server_config.auto_time;
  92                         continue;
  93                 } else if (retval < 0 && errno != EINTR) {
  94                         DEBUG("error on select");
  95                         continue;
  96                 }
  97
  98                 switch (udhcp_sp_read(&rfds)) {
  99                 case SIGUSR1:
 100                         bb_info_msg("Received a SIGUSR1");
 101                         write_leases();
 102                         /* why not just reset the timeout, eh */
 103                         timeout_end = time(0) + server_config.auto_time;
 104                         continue;
 105                 case SIGTERM:
 106                         bb_info_msg("Received a SIGTERM");
 107                         return 0;
 108                 case 0: break;          /* no signal */
 109                 default: continue;      /* signal or error (probably EINTR) */
 110                 }
 111
 112                 if ((bytes = udhcp_get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 113                         if (bytes == -1 && errno != EINTR) {
 114                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 115                                 close(server_socket);
 116                                 server_socket = -1;
 117                         }
 118                         continue;
 119                 }
 120
 121                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 122                         bb_error_msg("cannot get option from packet, ignoring");
 123                         continue;
 124                 }
 125
 126                 /* Look for a static lease */
 127                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 128
 129                 if (static_lease_ip) {
 130                         bb_info_msg("Found static lease: %x", static_lease_ip);
 131
 132                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 133                         static_lease.yiaddr = static_lease_ip;
 134                         static_lease.expires = 0;
 135
 136                         lease = &static_lease;
 137
 138                 } else {
 139                         lease = find_lease_by_chaddr(packet.chaddr);
 140                 }
 141
 142                 switch (state[0]) {
 143                 case DHCPDISCOVER:
 144                         DEBUG("Received DISCOVER");
 145
 146                         if (sendOffer(&packet) < 0) {
 147                                 bb_error_msg("send OFFER failed");
 148                         }
 149                         break;
 150                 case DHCPREQUEST:
 151                         DEBUG("received REQUEST");
 152
 153                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 154                         server_id = get_option(&packet, DHCP_SERVER_ID);
 155
 156                         if (requested) memcpy(&requested_align, requested, 4);
 157                         if (server_id) memcpy(&server_id_align, server_id, 4);
 158
 159                         if (lease) {
 160                                 if (server_id) {
 161                                         /* SELECTING State */
 162                                         DEBUG("server_id = %08x", ntohl(server_id_align));
 163                                         if (server_id_align == server_config.server && requested &&
 164                                             requested_align == lease->yiaddr) {
 165                                                 sendACK(&packet, lease->yiaddr);
 166                                         }
 167                                 } else {
 168                                         if (requested) {
 169                                                 /* INIT-REBOOT State */
 170                                                 if (lease->yiaddr == requested_align)
 171                                                         sendACK(&packet, lease->yiaddr);
 172                                                 else sendNAK(&packet);
 173                                         } else {
 174                                                 /* RENEWING or REBINDING State */
 175                                                 if (lease->yiaddr == packet.ciaddr)
 176                                                         sendACK(&packet, lease->yiaddr);
 177                                                 else {
 178                                                         /* don't know what to do!!!! */
 179                                                         sendNAK(&packet);
 180                                                 }
 181                                         }
 182                                 }
 183
 184                         /* what to do if we have no record of the client */
 185                         } else if (server_id) {
 186                                 /* SELECTING State */
 187
 188                         } else if (requested) {
 189                                 /* INIT-REBOOT State */
 190                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 191                                         if (lease_expired(lease)) {
 192                                                 /* probably best if we drop this lease */
 193                                                 memset(lease->chaddr, 0, 16);
 194                                         /* make some contention for this address */
 195                                         } else sendNAK(&packet);
 196                                 } else if (requested_align < server_config.start ||
 197                                            requested_align > server_config.end) {
 198                                         sendNAK(&packet);
 199                                 } /* else remain silent */
 200
 201                         } else {
 202                                  /* RENEWING or REBINDING State */
 203                         }
 204                         break;
 205                 case DHCPDECLINE:
 206                         DEBUG("Received DECLINE");
 207                         if (lease) {
 208                                 memset(lease->chaddr, 0, 16);
 209                                 lease->expires = time(0) + server_config.decline_time;
 210                         }
 211                         break;
 212                 case DHCPRELEASE:
 213                         DEBUG("Received RELEASE");
 214                         if (lease) lease->expires = time(0);
 215                         break;
 216                 case DHCPINFORM:
 217                         DEBUG("Received INFORM");
 218                         send_inform(&packet);
 219                         break;
 220                 default:
 221                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 222                 }
 223         }
 224
 225         return 0;
 226 }