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 <syslog.h>
  14 #include "common.h"
  15 #include "dhcpd.h"
  16 #include "options.h"
  17
  18
  19 /* globals */
  20 struct dhcpOfferedAddr *leases;
  21 struct server_config_t server_config;
  22
  23
  24 int udhcpd_main(int argc, char **argv);
  25 int udhcpd_main(int argc, char **argv)
  26 {
  27         fd_set rfds;
  28         struct timeval tv;
  29         int server_socket = -1, bytes, retval, max_sock;
  30         struct dhcpMessage packet;
  31         uint8_t *state, *server_id, *requested;
  32         uint32_t server_id_align, requested_align, static_lease_ip;
  33         unsigned long timeout_end, num_ips;
  34         struct option_set *option;
  35         struct dhcpOfferedAddr *lease, static_lease;
  36
  37 //Huh, dhcpd don't have --foreground, --syslog options?? TODO
  38
  39         if (!ENABLE_FEATURE_UDHCP_DEBUG) {
  40                 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
  41                 logmode &= ~LOGMODE_STDIO;
  42         }
  43
  44         if (ENABLE_FEATURE_UDHCP_SYSLOG) {
  45                 openlog(applet_name, LOG_PID, LOG_LOCAL0);
  46                 logmode |= LOGMODE_SYSLOG;
  47         }
  48
  49         /* Would rather not do read_config before daemonization -
  50          * otherwise NOMMU machines will parse config twice */
  51         read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]);
  52
  53         udhcp_make_pidfile(server_config.pidfile);
  54
  55         option = find_option(server_config.options, DHCP_LEASE_TIME);
  56         server_config.lease = LEASE_TIME;
  57         if (option) {
  58                 memcpy(&server_config.lease, option->data + 2, 4);
  59                 server_config.lease = ntohl(server_config.lease);
  60         }
  61
  62         /* Sanity check */
  63         num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1;
  64         if (server_config.max_leases > num_ips) {
  65                 bb_error_msg("max_leases value (%lu) not sane, "
  66                         "setting to %lu instead",
  67                         server_config.max_leases, num_ips);
  68                 server_config.max_leases = num_ips;
  69         }
  70
  71         leases = xzalloc(server_config.max_leases * sizeof(struct dhcpOfferedAddr));
  72         read_leases(server_config.lease_file);
  73
  74         if (read_interface(server_config.interface, &server_config.ifindex,
  75                            &server_config.server, server_config.arp) < 0) {
  76                 retval = 1;
  77                 goto ret;
  78         }
  79
  80         /* Setup the signal pipe */
  81         udhcp_sp_setup();
  82
  83         timeout_end = time(0) + server_config.auto_time;
  84         while (1) { /* loop until universe collapses */
  85
  86                 if (server_socket < 0) {
  87                         server_socket = listen_socket(INADDR_ANY, SERVER_PORT,
  88                                         server_config.interface);
  89                 }
  90
  91                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
  92                 if (server_config.auto_time) {
  93                         tv.tv_sec = timeout_end - time(0);
  94                         tv.tv_usec = 0;
  95                 }
  96                 retval = 0;
  97                 if (!server_config.auto_time || tv.tv_sec > 0) {
  98                         retval = select(max_sock + 1, &rfds, NULL, NULL,
  99                                         server_config.auto_time ? &tv : NULL);
 100                 }
 101                 if (retval == 0) {
 102                         write_leases();
 103                         timeout_end = time(0) + server_config.auto_time;
 104                         continue;
 105                 }
 106                 if (retval < 0 && errno != EINTR) {
 107                         DEBUG("error on select");
 108                         continue;
 109                 }
 110
 111                 switch (udhcp_sp_read(&rfds)) {
 112                 case SIGUSR1:
 113                         bb_info_msg("Received a SIGUSR1");
 114                         write_leases();
 115                         /* why not just reset the timeout, eh */
 116                         timeout_end = time(0) + server_config.auto_time;
 117                         continue;
 118                 case SIGTERM:
 119                         bb_info_msg("Received a SIGTERM");
 120                         goto ret0;
 121                 case 0: break;          /* no signal */
 122                 default: continue;      /* signal or error (probably EINTR) */
 123                 }
 124
 125                 bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */
 126                 if (bytes < 0) {
 127                         if (bytes == -1 && errno != EINTR) {
 128                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 129                                 close(server_socket);
 130                                 server_socket = -1;
 131                         }
 132                         continue;
 133                 }
 134
 135                 state = get_option(&packet, DHCP_MESSAGE_TYPE);
 136                 if (state == NULL) {
 137                         bb_error_msg("cannot get option from packet, ignoring");
 138                         continue;
 139                 }
 140
 141                 /* Look for a static lease */
 142                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 143
 144                 if (static_lease_ip) {
 145                         bb_info_msg("Found static lease: %x", static_lease_ip);
 146
 147                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 148                         static_lease.yiaddr = static_lease_ip;
 149                         static_lease.expires = 0;
 150
 151                         lease = &static_lease;
 152                 } else {
 153                         lease = find_lease_by_chaddr(packet.chaddr);
 154                 }
 155
 156                 switch (state[0]) {
 157                 case DHCPDISCOVER:
 158                         DEBUG("Received DISCOVER");
 159
 160                         if (sendOffer(&packet) < 0) {
 161                                 bb_error_msg("send OFFER failed");
 162                         }
 163                         break;
 164                 case DHCPREQUEST:
 165                         DEBUG("received REQUEST");
 166
 167                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 168                         server_id = get_option(&packet, DHCP_SERVER_ID);
 169
 170                         if (requested) memcpy(&requested_align, requested, 4);
 171                         if (server_id) memcpy(&server_id_align, server_id, 4);
 172
 173                         if (lease) {
 174                                 if (server_id) {
 175                                         /* SELECTING State */
 176                                         DEBUG("server_id = %08x", ntohl(server_id_align));
 177                                         if (server_id_align == server_config.server && requested
 178                                          && requested_align == lease->yiaddr
 179                                         ) {
 180                                                 sendACK(&packet, lease->yiaddr);
 181                                         }
 182                                 } else if (requested) {
 183                                         /* INIT-REBOOT State */
 184                                         if (lease->yiaddr == requested_align)
 185                                                 sendACK(&packet, lease->yiaddr);
 186                                         else
 187                                                 sendNAK(&packet);
 188                                 } else if (lease->yiaddr == packet.ciaddr) {
 189                                         /* RENEWING or REBINDING State */
 190                                         sendACK(&packet, lease->yiaddr);
 191                                 } else {
 192                                         /* don't know what to do!!!! */
 193                                         sendNAK(&packet);
 194                                 }
 195
 196                         /* what to do if we have no record of the client */
 197                         } else if (server_id) {
 198                                 /* SELECTING State */
 199
 200                         } else if (requested) {
 201                                 /* INIT-REBOOT State */
 202                                 lease = find_lease_by_yiaddr(requested_align);
 203                                 if (lease) {
 204                                         if (lease_expired(lease)) {
 205                                                 /* probably best if we drop this lease */
 206                                                 memset(lease->chaddr, 0, 16);
 207                                         /* make some contention for this address */
 208                                         } else
 209                                                 sendNAK(&packet);
 210                                 } else if (requested_align < server_config.start
 211                                         || requested_align > server_config.end
 212                                 ) {
 213                                         sendNAK(&packet);
 214                                 } /* else remain silent */
 215
 216                         } else {
 217                                 /* RENEWING or REBINDING State */
 218                         }
 219                         break;
 220                 case DHCPDECLINE:
 221                         DEBUG("Received DECLINE");
 222                         if (lease) {
 223                                 memset(lease->chaddr, 0, 16);
 224                                 lease->expires = time(0) + server_config.decline_time;
 225                         }
 226                         break;
 227                 case DHCPRELEASE:
 228                         DEBUG("Received RELEASE");
 229                         if (lease)
 230                                 lease->expires = time(0);
 231                         break;
 232                 case DHCPINFORM:
 233                         DEBUG("Received INFORM");
 234                         send_inform(&packet);
 235                         break;
 236                 default:
 237                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 238                 }
 239         }
 240  ret0:
 241         retval = 0;
 242  ret:
 243         if (server_config.pidfile)
 244                 remove_pidfile(server_config.pidfile);
 245         return retval;
 246 }