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 <fcntl.h>
  14 #include <string.h>
  15 #include <stdlib.h>
  16 #include <sys/wait.h>
  17 #include <arpa/inet.h>
  18 #include <netdb.h>
  19 #include <netinet/in.h>
  20 #include <sys/socket.h>
  21 #include <unistd.h>
  22 #include <signal.h>
  23 #include <errno.h>
  24 #include <sys/ioctl.h>
  25 #include <time.h>
  26
  27 #include "dhcpd.h"
  28 #include "arpping.h"
  29 #include "socket.h"
  30 #include "options.h"
  31 #include "files.h"
  32 #include "serverpacket.h"
  33 #include "common.h"
  34 #include "signalpipe.h"
  35 #include "static_leases.h"
  36
  37
  38 /* globals */
  39 struct dhcpOfferedAddr *leases;
  40 struct server_config_t server_config;
  41
  42
  43 int udhcpd_main(int argc, char *argv[])
  44 {
  45         fd_set rfds;
  46         struct timeval tv;
  47         int server_socket = -1, bytes, retval, max_sock;
  48         struct dhcpMessage packet;
  49         uint8_t *state, *server_id, *requested;
  50         uint32_t server_id_align, requested_align, static_lease_ip;
  51         unsigned long timeout_end, num_ips;
  52         struct option_set *option;
  53         struct dhcpOfferedAddr *lease, static_lease;
  54
  55         read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]);
  56
  57         /* Start the log, sanitize fd's, and write a pid file */
  58         udhcp_start_log_and_pid(server_config.pidfile);
  59
  60         if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) {
  61                 memcpy(&server_config.lease, option->data + 2, 4);
  62                 server_config.lease = ntohl(server_config.lease);
  63         }
  64         else server_config.lease = LEASE_TIME;
  65
  66         /* Sanity check */
  67         num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1;
  68         if (server_config.max_leases > num_ips) {
  69                 bb_error_msg("max_leases value (%lu) not sane, "
  70                         "setting to %lu instead",
  71                         server_config.max_leases, num_ips);
  72                 server_config.max_leases = num_ips;
  73         }
  74
  75         leases = xzalloc(server_config.max_leases * sizeof(struct dhcpOfferedAddr));
  76         read_leases(server_config.lease_file);
  77
  78         if (read_interface(server_config.interface, &server_config.ifindex,
  79                            &server_config.server, server_config.arp) < 0)
  80                 return 1;
  81
  82         if (!ENABLE_FEATURE_UDHCP_DEBUG)
  83                 udhcp_background(server_config.pidfile); /* hold lock during fork. */
  84
  85         /* Setup the signal pipe */
  86         udhcp_sp_setup();
  87
  88         timeout_end = time(0) + server_config.auto_time;
  89         while(1) { /* loop until universe collapses */
  90
  91                 if (server_socket < 0)
  92                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
  93                                 bb_perror_msg("FATAL: couldn't create server socket");
  94                                 return 2;
  95                         }
  96
  97                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
  98                 if (server_config.auto_time) {
  99                         tv.tv_sec = timeout_end - time(0);
 100                         tv.tv_usec = 0;
 101                 }
 102                 if (!server_config.auto_time || tv.tv_sec > 0) {
 103                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 104                                         server_config.auto_time ? &tv : NULL);
 105                 } else retval = 0; /* If we already timed out, fall through */
 106
 107                 if (retval == 0) {
 108                         write_leases();
 109                         timeout_end = time(0) + server_config.auto_time;
 110                         continue;
 111                 } else if (retval < 0 && errno != EINTR) {
 112                         DEBUG("error on select");
 113                         continue;
 114                 }
 115
 116                 switch (udhcp_sp_read(&rfds)) {
 117                 case SIGUSR1:
 118                         bb_info_msg("Received a SIGUSR1");
 119                         write_leases();
 120                         /* why not just reset the timeout, eh */
 121                         timeout_end = time(0) + server_config.auto_time;
 122                         continue;
 123                 case SIGTERM:
 124                         bb_info_msg("Received a SIGTERM");
 125                         return 0;
 126                 case 0: break;          /* no signal */
 127                 default: continue;      /* signal or error (probably EINTR) */
 128                 }
 129
 130                 if ((bytes = udhcp_get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 131                         if (bytes == -1 && errno != EINTR) {
 132                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 133                                 close(server_socket);
 134                                 server_socket = -1;
 135                         }
 136                         continue;
 137                 }
 138
 139                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 140                         bb_error_msg("Couldn't get option from packet, ignoring");
 141                         continue;
 142                 }
 143
 144                 /* Look for a static lease */
 145                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 146
 147                 if(static_lease_ip)
 148                 {
 149                         bb_info_msg("Found static lease: %x", static_lease_ip);
 150
 151                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 152                         static_lease.yiaddr = static_lease_ip;
 153                         static_lease.expires = 0;
 154
 155                         lease = &static_lease;
 156
 157                 }
 158                 else
 159                 {
 160                 lease = find_lease_by_chaddr(packet.chaddr);
 161                 }
 162
 163                 switch (state[0]) {
 164                 case DHCPDISCOVER:
 165                         DEBUG("Received DISCOVER");
 166
 167                         if (sendOffer(&packet) < 0) {
 168                                 bb_error_msg("Send OFFER failed");
 169                         }
 170                         break;
 171                 case DHCPREQUEST:
 172                         DEBUG("received REQUEST");
 173
 174                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 175                         server_id = get_option(&packet, DHCP_SERVER_ID);
 176
 177                         if (requested) memcpy(&requested_align, requested, 4);
 178                         if (server_id) memcpy(&server_id_align, server_id, 4);
 179
 180                         if (lease) {
 181                                 if (server_id) {
 182                                         /* SELECTING State */
 183                                         DEBUG("server_id = %08x", ntohl(server_id_align));
 184                                         if (server_id_align == server_config.server && requested &&
 185                                             requested_align == lease->yiaddr) {
 186                                                 sendACK(&packet, lease->yiaddr);
 187                                         }
 188                                 } else {
 189                                         if (requested) {
 190                                                 /* INIT-REBOOT State */
 191                                                 if (lease->yiaddr == requested_align)
 192                                                         sendACK(&packet, lease->yiaddr);
 193                                                 else sendNAK(&packet);
 194                                         } else {
 195                                                 /* RENEWING or REBINDING State */
 196                                                 if (lease->yiaddr == packet.ciaddr)
 197                                                         sendACK(&packet, lease->yiaddr);
 198                                                 else {
 199                                                         /* don't know what to do!!!! */
 200                                                         sendNAK(&packet);
 201                                                 }
 202                                         }
 203                                 }
 204
 205                         /* what to do if we have no record of the client */
 206                         } else if (server_id) {
 207                                 /* SELECTING State */
 208
 209                         } else if (requested) {
 210                                 /* INIT-REBOOT State */
 211                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 212                                         if (lease_expired(lease)) {
 213                                                 /* probably best if we drop this lease */
 214                                                 memset(lease->chaddr, 0, 16);
 215                                         /* make some contention for this address */
 216                                         } else sendNAK(&packet);
 217                                 } else if (requested_align < server_config.start ||
 218                                            requested_align > server_config.end) {
 219                                         sendNAK(&packet);
 220                                 } /* else remain silent */
 221
 222                         } else {
 223                                  /* RENEWING or REBINDING State */
 224                         }
 225                         break;
 226                 case DHCPDECLINE:
 227                         DEBUG("Received DECLINE");
 228                         if (lease) {
 229                                 memset(lease->chaddr, 0, 16);
 230                                 lease->expires = time(0) + server_config.decline_time;
 231                         }
 232                         break;
 233                 case DHCPRELEASE:
 234                         DEBUG("Received RELEASE");
 235                         if (lease) lease->expires = time(0);
 236                         break;
 237                 case DHCPINFORM:
 238                         DEBUG("Received INFORM");
 239                         send_inform(&packet);
 240                         break;
 241                 default:
 242                         bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
 243                 }
 244         }
 245
 246         return 0;
 247 }
 248