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         USE_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         opt = getopt32(argv, "fS" USE_FEATURE_UDHCP_PORT("P:", &str_P));
  48         argv += optind;
  49
  50         if (!(opt & 1)) { /* no -f */
  51                 bb_daemonize_or_rexec(0, argv);
  52                 logmode &= ~LOGMODE_STDIO;
  53         }
  54
  55         if (opt & 2) { /* -S */
  56                 openlog(applet_name, LOG_PID, LOG_LOCAL0);
  57                 logmode |= LOGMODE_SYSLOG;
  58         }
  59 #if ENABLE_FEATURE_UDHCP_PORT
  60         if (opt & 4) { /* -P */
  61                 SERVER_PORT = xatou16(str_P);
  62                 CLIENT_PORT = SERVER_PORT + 1;
  63         }
  64 #endif
  65         /* Would rather not do read_config before daemonization -
  66          * otherwise NOMMU machines will parse config twice */
  67         read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
  68
  69         /* Make sure fd 0,1,2 are open */
  70         bb_sanitize_stdio();
  71         /* Equivalent of doing a fflush after every \n */
  72         setlinebuf(stdout);
  73
  74         /* Create pidfile */
  75         write_pidfile(server_config.pidfile);
  76         /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
  77
  78         bb_info_msg("%s (v"BB_VER") started", applet_name);
  79
  80         option = find_option(server_config.options, DHCP_LEASE_TIME);
  81         server_config.lease = LEASE_TIME;
  82         if (option) {
  83                 move_from_unaligned32(server_config.lease, option->data + 2);
  84                 server_config.lease = ntohl(server_config.lease);
  85         }
  86
  87         /* Sanity check */
  88         num_ips = server_config.end_ip - server_config.start_ip + 1;
  89         if (server_config.max_leases > num_ips) {
  90                 bb_error_msg("max_leases=%u is too big, setting to %u",
  91                         (unsigned)server_config.max_leases, num_ips);
  92                 server_config.max_leases = num_ips;
  93         }
  94
  95         leases = xzalloc(server_config.max_leases * sizeof(*leases));
  96         read_leases(server_config.lease_file);
  97
  98         if (udhcp_read_interface(server_config.interface, &server_config.ifindex,
  99                            &server_config.server, server_config.arp)) {
 100                 retval = 1;
 101                 goto ret;
 102         }
 103
 104         /* Setup the signal pipe */
 105         udhcp_sp_setup();
 106
 107         timeout_end = monotonic_sec() + server_config.auto_time;
 108         while (1) { /* loop until universe collapses */
 109                 int bytes;
 110                 struct timeval tv;
 111
 112                 if (server_socket < 0) {
 113                         server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
 114                                         server_config.interface);
 115                 }
 116
 117                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
 118                 if (server_config.auto_time) {
 119                         tv.tv_sec = timeout_end - monotonic_sec();
 120                         tv.tv_usec = 0;
 121                 }
 122                 retval = 0;
 123                 if (!server_config.auto_time || tv.tv_sec > 0) {
 124                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 125                                         server_config.auto_time ? &tv : NULL);
 126                 }
 127                 if (retval == 0) {
 128                         write_leases();
 129                         timeout_end = monotonic_sec() + server_config.auto_time;
 130                         continue;
 131                 }
 132                 if (retval < 0 && errno != EINTR) {
 133                         DEBUG("error on select");
 134                         continue;
 135                 }
 136
 137                 switch (udhcp_sp_read(&rfds)) {
 138                 case SIGUSR1:
 139                         bb_info_msg("Received a SIGUSR1");
 140                         write_leases();
 141                         /* why not just reset the timeout, eh */
 142                         timeout_end = monotonic_sec() + server_config.auto_time;
 143                         continue;
 144                 case SIGTERM:
 145                         bb_info_msg("Received a SIGTERM");
 146                         goto ret0;
 147                 case 0: /* no signal: read a packet */
 148                         break;
 149                 default: /* signal or error (probably EINTR): back to select */
 150                         continue;
 151                 }
 152
 153                 bytes = udhcp_recv_kernel_packet(&packet, server_socket);
 154                 if (bytes < 0) {
 155                         /* bytes can also be -2 ("bad packet data") */
 156                         if (bytes == -1 && errno != EINTR) {
 157                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 158                                 close(server_socket);
 159                                 server_socket = -1;
 160                         }
 161                         continue;
 162                 }
 163
 164                 state = get_option(&packet, DHCP_MESSAGE_TYPE);
 165                 if (state == NULL) {
 166                         bb_error_msg("cannot get option from packet, ignoring");
 167                         continue;
 168                 }
 169
 170                 /* Look for a static lease */
 171                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 172                 if (static_lease_ip) {
 173                         bb_info_msg("Found static lease: %x", static_lease_ip);
 174
 175                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 176                         static_lease.yiaddr = static_lease_ip;
 177                         static_lease.expires = 0;
 178
 179                         lease = &static_lease;
 180                 } else {
 181                         lease = find_lease_by_chaddr(packet.chaddr);
 182                 }
 183
 184                 switch (state[0]) {
 185                 case DHCPDISCOVER:
 186                         DEBUG("Received DISCOVER");
 187
 188                         if (send_offer(&packet) < 0) {
 189                                 bb_error_msg("send OFFER failed");
 190                         }
 191                         break;
 192                 case DHCPREQUEST:
 193                         DEBUG("received REQUEST");
 194
 195                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 196                         server_id = get_option(&packet, DHCP_SERVER_ID);
 197
 198                         if (requested)
 199                                 move_from_unaligned32(requested_aligned, requested);
 200                         if (server_id)
 201                                 move_from_unaligned32(server_id_aligned, server_id);
 202
 203                         if (lease) {
 204                                 if (server_id) {
 205                                         /* SELECTING State */
 206                                         DEBUG("server_id = %08x", ntohl(server_id_aligned));
 207                                         if (server_id_aligned == server_config.server
 208                                          && requested
 209                                          && requested_aligned == lease->yiaddr
 210                                         ) {
 211                                                 send_ACK(&packet, lease->yiaddr);
 212                                         }
 213                                 } else if (requested) {
 214                                         /* INIT-REBOOT State */
 215                                         if (lease->yiaddr == requested_aligned)
 216                                                 send_ACK(&packet, lease->yiaddr);
 217                                         else
 218                                                 send_NAK(&packet);
 219                                 } else if (lease->yiaddr == packet.ciaddr) {
 220                                         /* RENEWING or REBINDING State */
 221                                         send_ACK(&packet, lease->yiaddr);
 222                                 } else { /* don't know what to do!!!! */
 223                                         send_NAK(&packet);
 224                                 }
 225
 226                         /* what to do if we have no record of the client */
 227                         } else if (server_id) {
 228                                 /* SELECTING State */
 229
 230                         } else if (requested) {
 231                                 /* INIT-REBOOT State */
 232                                 lease = find_lease_by_yiaddr(requested_aligned);
 233                                 if (lease) {
 234                                         if (lease_expired(lease)) {
 235                                                 /* probably best if we drop this lease */
 236                                                 memset(lease->chaddr, 0, 16);
 237                                         /* make some contention for this address */
 238                                         } else
 239                                                 send_NAK(&packet);
 240                                 } else {
 241                                         uint32_t r = ntohl(requested_aligned);
 242                                         if (r < server_config.start_ip
 243                                          || r > server_config.end_ip
 244                                         ) {
 245                                                 send_NAK(&packet);
 246                                         }
 247                                         /* else remain silent */
 248                                 }
 249
 250                         } else {
 251                                 /* RENEWING or REBINDING State */
 252                         }
 253                         break;
 254                 case DHCPDECLINE:
 255                         DEBUG("Received DECLINE");
 256                         if (lease) {
 257                                 memset(lease->chaddr, 0, 16);
 258                                 lease->expires = time(NULL) + server_config.decline_time;
 259                         }
 260                         break;
 261                 case DHCPRELEASE:
 262                         DEBUG("Received RELEASE");
 263                         if (lease)
 264                                 lease->expires = time(NULL);
 265                         break;
 266                 case DHCPINFORM:
 267                         DEBUG("Received INFORM");
 268                         send_inform(&packet);
 269                         break;
 270                 default:
 271                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 272                 }
 273         }
 274  ret0:
 275         retval = 0;
 276  ret:
 277         /*if (server_config.pidfile) - server_config.pidfile is never NULL */
 278                 remove_pidfile(server_config.pidfile);
 279         return retval;
 280 }