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                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
  73                                 bb_perror_msg("FATAL: cannot create server socket");
  74                                 return 2;
  75                         }
  76
  77                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
  78                 if (server_config.auto_time) {
  79                         tv.tv_sec = timeout_end - time(0);
  80                         tv.tv_usec = 0;
  81                 }
  82                 if (!server_config.auto_time || tv.tv_sec > 0) {
  83                         retval = select(max_sock + 1, &rfds, NULL, NULL,
  84                                         server_config.auto_time ? &tv : NULL);
  85                 } else retval = 0; /* If we already timed out, fall through */
  86
  87                 if (retval == 0) {
  88                         write_leases();
  89                         timeout_end = time(0) + server_config.auto_time;
  90                         continue;
  91                 } else if (retval < 0 && errno != EINTR) {
  92                         DEBUG("error on select");
  93                         continue;
  94                 }
  95
  96                 switch (udhcp_sp_read(&rfds)) {
  97                 case SIGUSR1:
  98                         bb_info_msg("Received a SIGUSR1");
  99                         write_leases();
 100                         /* why not just reset the timeout, eh */
 101                         timeout_end = time(0) + server_config.auto_time;
 102                         continue;
 103                 case SIGTERM:
 104                         bb_info_msg("Received a SIGTERM");
 105                         return 0;
 106                 case 0: break;          /* no signal */
 107                 default: continue;      /* signal or error (probably EINTR) */
 108                 }
 109
 110                 if ((bytes = udhcp_get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 111                         if (bytes == -1 && errno != EINTR) {
 112                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 113                                 close(server_socket);
 114                                 server_socket = -1;
 115                         }
 116                         continue;
 117                 }
 118
 119                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 120                         bb_error_msg("cannot get option from packet, ignoring");
 121                         continue;
 122                 }
 123
 124                 /* Look for a static lease */
 125                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 126
 127                 if (static_lease_ip) {
 128                         bb_info_msg("Found static lease: %x", static_lease_ip);
 129
 130                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 131                         static_lease.yiaddr = static_lease_ip;
 132                         static_lease.expires = 0;
 133
 134                         lease = &static_lease;
 135
 136                 } else {
 137                         lease = find_lease_by_chaddr(packet.chaddr);
 138                 }
 139
 140                 switch (state[0]) {
 141                 case DHCPDISCOVER:
 142                         DEBUG("Received DISCOVER");
 143
 144                         if (sendOffer(&packet) < 0) {
 145                                 bb_error_msg("send OFFER failed");
 146                         }
 147                         break;
 148                 case DHCPREQUEST:
 149                         DEBUG("received REQUEST");
 150
 151                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 152                         server_id = get_option(&packet, DHCP_SERVER_ID);
 153
 154                         if (requested) memcpy(&requested_align, requested, 4);
 155                         if (server_id) memcpy(&server_id_align, server_id, 4);
 156
 157                         if (lease) {
 158                                 if (server_id) {
 159                                         /* SELECTING State */
 160                                         DEBUG("server_id = %08x", ntohl(server_id_align));
 161                                         if (server_id_align == server_config.server && requested &&
 162                                             requested_align == lease->yiaddr) {
 163                                                 sendACK(&packet, lease->yiaddr);
 164                                         }
 165                                 } else {
 166                                         if (requested) {
 167                                                 /* INIT-REBOOT State */
 168                                                 if (lease->yiaddr == requested_align)
 169                                                         sendACK(&packet, lease->yiaddr);
 170                                                 else sendNAK(&packet);
 171                                         } else {
 172                                                 /* RENEWING or REBINDING State */
 173                                                 if (lease->yiaddr == packet.ciaddr)
 174                                                         sendACK(&packet, lease->yiaddr);
 175                                                 else {
 176                                                         /* don't know what to do!!!! */
 177                                                         sendNAK(&packet);
 178                                                 }
 179                                         }
 180                                 }
 181
 182                         /* what to do if we have no record of the client */
 183                         } else if (server_id) {
 184                                 /* SELECTING State */
 185
 186                         } else if (requested) {
 187                                 /* INIT-REBOOT State */
 188                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 189                                         if (lease_expired(lease)) {
 190                                                 /* probably best if we drop this lease */
 191                                                 memset(lease->chaddr, 0, 16);
 192                                         /* make some contention for this address */
 193                                         } else sendNAK(&packet);
 194                                 } else if (requested_align < server_config.start ||
 195                                            requested_align > server_config.end) {
 196                                         sendNAK(&packet);
 197                                 } /* else remain silent */
 198
 199                         } else {
 200                                  /* RENEWING or REBINDING State */
 201                         }
 202                         break;
 203                 case DHCPDECLINE:
 204                         DEBUG("Received DECLINE");
 205                         if (lease) {
 206                                 memset(lease->chaddr, 0, 16);
 207                                 lease->expires = time(0) + server_config.decline_time;
 208                         }
 209                         break;
 210                 case DHCPRELEASE:
 211                         DEBUG("Received RELEASE");
 212                         if (lease) lease->expires = time(0);
 213                         break;
 214                 case DHCPINFORM:
 215                         DEBUG("Received INFORM");
 216                         send_inform(&packet);
 217                         break;
 218                 default:
 219                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 220                 }
 221         }
 222
 223         return 0;
 224 }