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