git.maemo.org Git - busybox4maemo/blob - 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 ATTRIBUTE_UNUSED, char **argv)
  27 {
  28         fd_set rfds;
  29         struct timeval tv;
  30         int server_socket = -1, bytes, retval, max_sock;
  31         struct dhcpMessage packet;
  32         uint8_t *state, *server_id, *requested;
  33         uint32_t server_id_align, requested_align, static_lease_ip;
  34         unsigned timeout_end;
  35         unsigned num_ips;
  36         unsigned opt;
  37         struct option_set *option;
  38         struct dhcpOfferedAddr *lease, static_lease;
  39         USE_FEATURE_UDHCP_PORT(char *str_P;)
  40
  41 #if ENABLE_FEATURE_UDHCP_PORT
  42         SERVER_PORT = 67;
  43         CLIENT_PORT = 68;
  44 #endif
  45
  46         opt = getopt32(argv, "fS" USE_FEATURE_UDHCP_PORT("P:", &str_P));
  47         argv += optind;
  48
  49         if (!(opt & 1)) { /* no -f */
  50                 bb_daemonize_or_rexec(0, argv);
  51                 logmode &= ~LOGMODE_STDIO;
  52         }
  53
  54         if (opt & 2) { /* -S */
  55                 openlog(applet_name, LOG_PID, LOG_LOCAL0);
  56                 logmode |= LOGMODE_SYSLOG;
  57         }
  58 #if ENABLE_FEATURE_UDHCP_PORT
  59         if (opt & 4) { /* -P */
  60                 SERVER_PORT = xatou16(str_P);
  61                 CLIENT_PORT = SERVER_PORT + 1;
  62         }
  63 #endif
  64         /* Would rather not do read_config before daemonization -
  65          * otherwise NOMMU machines will parse config twice */
  66         read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
  67
  68         /* Make sure fd 0,1,2 are open */
  69         bb_sanitize_stdio();
  70         /* Equivalent of doing a fflush after every \n */
  71         setlinebuf(stdout);
  72
  73         /* Create pidfile */
  74         write_pidfile(server_config.pidfile);
  75         /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
  76
  77         bb_info_msg("%s (v"BB_VER") started", applet_name);
  78
  79         option = find_option(server_config.options, DHCP_LEASE_TIME);
  80         server_config.lease = LEASE_TIME;
  81         if (option) {
  82                 memcpy(&server_config.lease, option->data + 2, 4);
  83                 server_config.lease = ntohl(server_config.lease);
  84         }
  85
  86         /* Sanity check */
  87         num_ips = server_config.end_ip - server_config.start_ip + 1;
  88         if (server_config.max_leases > num_ips) {
  89                 bb_error_msg("max_leases=%u is too big, setting to %u",
  90                         (unsigned)server_config.max_leases, num_ips);
  91                 server_config.max_leases = num_ips;
  92         }
  93
  94         leases = xzalloc(server_config.max_leases * sizeof(*leases));
  95         read_leases(server_config.lease_file);
  96
  97         if (read_interface(server_config.interface, &server_config.ifindex,
  98                            &server_config.server, server_config.arp)) {
  99                 retval = 1;
 100                 goto ret;
 101         }
 102
 103         /* Setup the signal pipe */
 104         udhcp_sp_setup();
 105
 106         timeout_end = monotonic_sec() + server_config.auto_time;
 107         while (1) { /* loop until universe collapses */
 108
 109                 if (server_socket < 0) {
 110                         server_socket = listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
 111                                         server_config.interface);
 112                 }
 113
 114                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
 115                 if (server_config.auto_time) {
 116                         tv.tv_sec = timeout_end - monotonic_sec();
 117                         tv.tv_usec = 0;
 118                 }
 119                 retval = 0;
 120                 if (!server_config.auto_time || tv.tv_sec > 0) {
 121                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 122                                         server_config.auto_time ? &tv : NULL);
 123                 }
 124                 if (retval == 0) {
 125                         write_leases();
 126                         timeout_end = monotonic_sec() + server_config.auto_time;
 127                         continue;
 128                 }
 129                 if (retval < 0 && errno != EINTR) {
 130                         DEBUG("error on select");
 131                         continue;
 132                 }
 133
 134                 switch (udhcp_sp_read(&rfds)) {
 135                 case SIGUSR1:
 136                         bb_info_msg("Received a SIGUSR1");
 137                         write_leases();
 138                         /* why not just reset the timeout, eh */
 139                         timeout_end = monotonic_sec() + server_config.auto_time;
 140                         continue;
 141                 case SIGTERM:
 142                         bb_info_msg("Received a SIGTERM");
 143                         goto ret0;
 144                 case 0: break;          /* no signal */
 145                 default: continue;      /* signal or error (probably EINTR) */
 146                 }
 147
 148                 bytes = udhcp_recv_packet(&packet, server_socket); /* this waits for a packet - idle */
 149                 if (bytes < 0) {
 150                         if (bytes == -1 && errno != EINTR) {
 151                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 152                                 close(server_socket);
 153                                 server_socket = -1;
 154                         }
 155                         continue;
 156                 }
 157
 158                 state = get_option(&packet, DHCP_MESSAGE_TYPE);
 159                 if (state == NULL) {
 160                         bb_error_msg("cannot get option from packet, ignoring");
 161                         continue;
 162                 }
 163
 164                 /* Look for a static lease */
 165                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 166
 167                 if (static_lease_ip) {
 168                         bb_info_msg("Found static lease: %x", static_lease_ip);
 169
 170                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 171                         static_lease.yiaddr = static_lease_ip;
 172                         static_lease.expires = 0;
 173
 174                         lease = &static_lease;
 175                 } else {
 176                         lease = find_lease_by_chaddr(packet.chaddr);
 177                 }
 178
 179                 switch (state[0]) {
 180                 case DHCPDISCOVER:
 181                         DEBUG("Received DISCOVER");
 182
 183                         if (sendOffer(&packet) < 0) {
 184                                 bb_error_msg("send OFFER failed");
 185                         }
 186                         break;
 187                 case DHCPREQUEST:
 188                         DEBUG("received REQUEST");
 189
 190                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 191                         server_id = get_option(&packet, DHCP_SERVER_ID);
 192
 193                         if (requested) memcpy(&requested_align, requested, 4);
 194                         if (server_id) memcpy(&server_id_align, server_id, 4);
 195
 196                         if (lease) {
 197                                 if (server_id) {
 198                                         /* SELECTING State */
 199                                         DEBUG("server_id = %08x", ntohl(server_id_align));
 200                                         if (server_id_align == server_config.server && requested
 201                                          && requested_align == lease->yiaddr
 202                                         ) {
 203                                                 sendACK(&packet, lease->yiaddr);
 204                                         }
 205                                 } else if (requested) {
 206                                         /* INIT-REBOOT State */
 207                                         if (lease->yiaddr == requested_align)
 208                                                 sendACK(&packet, lease->yiaddr);
 209                                         else
 210                                                 sendNAK(&packet);
 211                                 } else if (lease->yiaddr == packet.ciaddr) {
 212                                         /* RENEWING or REBINDING State */
 213                                         sendACK(&packet, lease->yiaddr);
 214                                 } else {
 215                                         /* don't know what to do!!!! */
 216                                         sendNAK(&packet);
 217                                 }
 218
 219                         /* what to do if we have no record of the client */
 220                         } else if (server_id) {
 221                                 /* SELECTING State */
 222
 223                         } else if (requested) {
 224                                 /* INIT-REBOOT State */
 225                                 lease = find_lease_by_yiaddr(requested_align);
 226                                 if (lease) {
 227                                         if (lease_expired(lease)) {
 228                                                 /* probably best if we drop this lease */
 229                                                 memset(lease->chaddr, 0, 16);
 230                                         /* make some contention for this address */
 231                                         } else
 232                                                 sendNAK(&packet);
 233                                 } else {
 234                                         uint32_t r = ntohl(requested_align);
 235                                         if (r < server_config.start_ip
 236                                          || r > server_config.end_ip
 237                                         ) {
 238                                                 sendNAK(&packet);
 239                                         }
 240                                         /* else remain silent */
 241                                 }
 242
 243                         } else {
 244                                 /* RENEWING or REBINDING State */
 245                         }
 246                         break;
 247                 case DHCPDECLINE:
 248                         DEBUG("Received DECLINE");
 249                         if (lease) {
 250                                 memset(lease->chaddr, 0, 16);
 251                                 lease->expires = time(0) + server_config.decline_time;
 252                         }
 253                         break;
 254                 case DHCPRELEASE:
 255                         DEBUG("Received RELEASE");
 256                         if (lease)
 257                                 lease->expires = time(0);
 258                         break;
 259                 case DHCPINFORM:
 260                         DEBUG("Received INFORM");
 261                         send_inform(&packet);
 262                         break;
 263                 default:
 264                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 265                 }
 266         }
 267  ret0:
 268         retval = 0;
 269  ret:
 270         /*if (server_config.pidfile) - server_config.pidfile is never NULL */
 271                 remove_pidfile(server_config.pidfile);
 272         return retval;
 273 }