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 "dhcpc.h"
  16 #include "dhcpd.h"
  17 #include "options.h"
  18
  19
  20 /* globals */
  21 struct dhcpOfferedAddr *leases;
  22 /* struct server_config_t server_config is in bb_common_bufsiz1 */
  23
  24
  25 int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  26 int udhcpd_main(int argc UNUSED_PARAM, char **argv)
  27 {
  28         fd_set rfds;
  29         int server_socket = -1, retval, max_sock;
  30         struct dhcpMessage packet;
  31         uint8_t *state, *server_id, *requested;
  32         uint32_t server_id_aligned = server_id_aligned; /* for compiler */
  33         uint32_t requested_aligned = requested_aligned;
  34         uint32_t static_lease_ip;
  35         unsigned timeout_end;
  36         unsigned num_ips;
  37         unsigned opt;
  38         struct option_set *option;
  39         struct dhcpOfferedAddr *lease, static_lease;
  40         IF_FEATURE_UDHCP_PORT(char *str_P;)
  41
  42 #if ENABLE_FEATURE_UDHCP_PORT
  43         SERVER_PORT = 67;
  44         CLIENT_PORT = 68;
  45 #endif
  46
  47 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
  48         opt_complementary = "vv";
  49 #endif
  50         opt = getopt32(argv, "fSv"
  51                 IF_FEATURE_UDHCP_PORT("P:", &str_P)
  52 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
  53                 , &dhcp_verbose
  54 #endif
  55                 );
  56         argv += optind;
  57         if (!(opt & 1)) { /* no -f */
  58                 bb_daemonize_or_rexec(0, argv);
  59                 logmode = LOGMODE_NONE;
  60         }
  61         if (opt & 2) { /* -S */
  62                 openlog(applet_name, LOG_PID, LOG_DAEMON);
  63                 logmode |= LOGMODE_SYSLOG;
  64         }
  65 #if ENABLE_FEATURE_UDHCP_PORT
  66         if (opt & 4) { /* -P */
  67                 SERVER_PORT = xatou16(str_P);
  68                 CLIENT_PORT = SERVER_PORT + 1;
  69         }
  70 #endif
  71         /* Would rather not do read_config before daemonization -
  72          * otherwise NOMMU machines will parse config twice */
  73         read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
  74
  75         /* Make sure fd 0,1,2 are open */
  76         bb_sanitize_stdio();
  77         /* Equivalent of doing a fflush after every \n */
  78         setlinebuf(stdout);
  79
  80         /* Create pidfile */
  81         write_pidfile(server_config.pidfile);
  82         /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
  83
  84         bb_info_msg("%s (v"BB_VER") started", applet_name);
  85
  86         option = find_option(server_config.options, DHCP_LEASE_TIME);
  87         server_config.lease = LEASE_TIME;
  88         if (option) {
  89                 move_from_unaligned32(server_config.lease, option->data + 2);
  90                 server_config.lease = ntohl(server_config.lease);
  91         }
  92
  93         /* Sanity check */
  94         num_ips = server_config.end_ip - server_config.start_ip + 1;
  95         if (server_config.max_leases > num_ips) {
  96                 bb_error_msg("max_leases=%u is too big, setting to %u",
  97                         (unsigned)server_config.max_leases, num_ips);
  98                 server_config.max_leases = num_ips;
  99         }
 100
 101         leases = xzalloc(server_config.max_leases * sizeof(*leases));
 102         read_leases(server_config.lease_file);
 103
 104         if (udhcp_read_interface(server_config.interface,
 105                         &server_config.ifindex,
 106                         &server_config.server_nip,
 107                         server_config.server_mac)
 108         ) {
 109                 retval = 1;
 110                 goto ret;
 111         }
 112
 113         /* Setup the signal pipe */
 114         udhcp_sp_setup();
 115
 116         timeout_end = monotonic_sec() + server_config.auto_time;
 117         while (1) { /* loop until universe collapses */
 118                 int bytes;
 119                 struct timeval tv;
 120
 121                 if (server_socket < 0) {
 122                         server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
 123                                         server_config.interface);
 124                 }
 125
 126                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
 127                 if (server_config.auto_time) {
 128                         tv.tv_sec = timeout_end - monotonic_sec();
 129                         tv.tv_usec = 0;
 130                 }
 131                 retval = 0;
 132                 if (!server_config.auto_time || tv.tv_sec > 0) {
 133                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 134                                         server_config.auto_time ? &tv : NULL);
 135                 }
 136                 if (retval == 0) {
 137                         write_leases();
 138                         timeout_end = monotonic_sec() + server_config.auto_time;
 139                         continue;
 140                 }
 141                 if (retval < 0 && errno != EINTR) {
 142                         log1("Error on select");
 143                         continue;
 144                 }
 145
 146                 switch (udhcp_sp_read(&rfds)) {
 147                 case SIGUSR1:
 148                         bb_info_msg("Received a SIGUSR1");
 149                         write_leases();
 150                         /* why not just reset the timeout, eh */
 151                         timeout_end = monotonic_sec() + server_config.auto_time;
 152                         continue;
 153                 case SIGTERM:
 154                         bb_info_msg("Received a SIGTERM");
 155                         goto ret0;
 156                 case 0: /* no signal: read a packet */
 157                         break;
 158                 default: /* signal or error (probably EINTR): back to select */
 159                         continue;
 160                 }
 161
 162                 bytes = udhcp_recv_kernel_packet(&packet, server_socket);
 163                 if (bytes < 0) {
 164                         /* bytes can also be -2 ("bad packet data") */
 165                         if (bytes == -1 && errno != EINTR) {
 166                                 log1("Read error: %s, reopening socket", strerror(errno));
 167                                 close(server_socket);
 168                                 server_socket = -1;
 169                         }
 170                         continue;
 171                 }
 172
 173                 state = get_option(&packet, DHCP_MESSAGE_TYPE);
 174                 if (state == NULL) {
 175                         bb_error_msg("no message type option, ignoring packet");
 176                         continue;
 177                 }
 178
 179                 /* Look for a static lease */
 180                 static_lease_ip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
 181                 if (static_lease_ip) {
 182                         bb_info_msg("Found static lease: %x", static_lease_ip);
 183
 184                         memcpy(&static_lease.lease_mac16, &packet.chaddr, 16);
 185                         static_lease.lease_nip = static_lease_ip;
 186                         static_lease.expires = 0;
 187
 188                         lease = &static_lease;
 189                 } else {
 190                         lease = find_lease_by_chaddr(packet.chaddr);
 191                 }
 192
 193                 switch (state[0]) {
 194                 case DHCPDISCOVER:
 195                         log1("Received DISCOVER");
 196
 197                         if (send_offer(&packet) < 0) {
 198                                 bb_error_msg("send OFFER failed");
 199                         }
 200                         break;
 201                 case DHCPREQUEST:
 202                         log1("Received REQUEST");
 203
 204                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 205                         server_id = get_option(&packet, DHCP_SERVER_ID);
 206
 207                         if (requested)
 208                                 move_from_unaligned32(requested_aligned, requested);
 209                         if (server_id)
 210                                 move_from_unaligned32(server_id_aligned, server_id);
 211
 212                         if (lease) {
 213                                 if (server_id) {
 214                                         /* SELECTING State */
 215                                         log1("server_id = %08x", ntohl(server_id_aligned));
 216                                         if (server_id_aligned == server_config.server_nip
 217                                          && requested
 218                                          && requested_aligned == lease->lease_nip
 219                                         ) {
 220                                                 send_ACK(&packet, lease->lease_nip);
 221                                         }
 222                                 } else if (requested) {
 223                                         /* INIT-REBOOT State */
 224                                         if (lease->lease_nip == requested_aligned)
 225                                                 send_ACK(&packet, lease->lease_nip);
 226                                         else
 227                                                 send_NAK(&packet);
 228                                 } else if (lease->lease_nip == packet.ciaddr) {
 229                                         /* RENEWING or REBINDING State */
 230                                         send_ACK(&packet, lease->lease_nip);
 231                                 } else { /* don't know what to do!!!! */
 232                                         send_NAK(&packet);
 233                                 }
 234
 235                         /* what to do if we have no record of the client */
 236                         } else if (server_id) {
 237                                 /* SELECTING State */
 238
 239                         } else if (requested) {
 240                                 /* INIT-REBOOT State */
 241                                 lease = find_lease_by_yiaddr(requested_aligned);
 242                                 if (lease) {
 243                                         if (lease_expired(lease)) {
 244                                                 /* probably best if we drop this lease */
 245                                                 memset(lease->lease_mac16, 0, 16);
 246                                         } else {
 247                                                 /* make some contention for this address */
 248                                                 send_NAK(&packet);
 249                                         }
 250                                 } else {
 251                                         uint32_t r = ntohl(requested_aligned);
 252                                         if (r < server_config.start_ip
 253                                          || r > server_config.end_ip
 254                                         ) {
 255                                                 send_NAK(&packet);
 256                                         }
 257                                         /* else remain silent */
 258                                 }
 259
 260                         } else {
 261                                 /* RENEWING or REBINDING State */
 262                         }
 263                         break;
 264                 case DHCPDECLINE:
 265                         log1("Received DECLINE");
 266                         if (lease) {
 267                                 memset(lease->lease_mac16, 0, 16);
 268                                 lease->expires = time(NULL) + server_config.decline_time;
 269                         }
 270                         break;
 271                 case DHCPRELEASE:
 272                         log1("Received RELEASE");
 273                         if (lease)
 274                                 lease->expires = time(NULL);
 275                         break;
 276                 case DHCPINFORM:
 277                         log1("Received INFORM");
 278                         send_inform(&packet);
 279                         break;
 280                 default:
 281                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 282                 }
 283         }
 284  ret0:
 285         retval = 0;
 286  ret:
 287         /*if (server_config.pidfile) - server_config.pidfile is never NULL */
 288                 remove_pidfile(server_config.pidfile);
 289         return retval;
 290 }