networking/udhcp/dhcpd.c

   1 /* dhcpd.c
   2  *
   3  * udhcp Server
   4  * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
   5  *                      Chris Trew <ctrew@moreton.com.au>
   6  *
   7  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   8  *
   9  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  10  */
  11
  12 #include <fcntl.h>
  13 #include <string.h>
  14 #include <stdlib.h>
  15 #include <sys/wait.h>
  16 #include <arpa/inet.h>
  17 #include <netdb.h>
  18 #include <netinet/in.h>
  19 #include <sys/socket.h>
  20 #include <unistd.h>
  21 #include <signal.h>
  22 #include <errno.h>
  23 #include <sys/ioctl.h>
  24 #include <time.h>
  25
  26 #include "dhcpd.h"
  27 #include "arpping.h"
  28 #include "socket.h"
  29 #include "options.h"
  30 #include "files.h"
  31 #include "serverpacket.h"
  32 #include "common.h"
  33 #include "signalpipe.h"
  34 #include "static_leases.h"
  35
  36
  37 /* globals */
  38 struct dhcpOfferedAddr *leases;
  39 struct server_config_t server_config;
  40
  41
  42 int udhcpd_main(int argc, char *argv[])
  43 {
  44         fd_set rfds;
  45         struct timeval tv;
  46         int server_socket = -1, bytes, retval, max_sock;
  47         struct dhcpMessage packet;
  48         uint8_t *state, *server_id, *requested;
  49         uint32_t server_id_align, requested_align, static_lease_ip;
  50         unsigned long timeout_end, num_ips;
  51         struct option_set *option;
  52         struct dhcpOfferedAddr *lease, static_lease;
  53
  54         read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]);
  55
  56         /* Start the log, sanitize fd's, and write a pid file */
  57         udhcp_start_log_and_pid("udhcpd", server_config.pidfile);
  58
  59         if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) {
  60                 memcpy(&server_config.lease, option->data + 2, 4);
  61                 server_config.lease = ntohl(server_config.lease);
  62         }
  63         else server_config.lease = LEASE_TIME;
  64
  65         /* Sanity check */
  66         num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1;
  67         if (server_config.max_leases > num_ips) {
  68                 LOG(LOG_ERR, "max_leases value (%lu) not sane, "
  69                         "setting to %lu instead",
  70                         server_config.max_leases, num_ips);
  71                 server_config.max_leases = num_ips;
  72         }
  73
  74         leases = xzalloc(server_config.max_leases * sizeof(struct dhcpOfferedAddr));
  75         read_leases(server_config.lease_file);
  76
  77         if (read_interface(server_config.interface, &server_config.ifindex,
  78                            &server_config.server, server_config.arp) < 0)
  79                 return 1;
  80
  81         if (!ENABLE_FEATURE_UDHCP_DEBUG)
  82                 udhcp_background(server_config.pidfile); /* hold lock during fork. */
  83
  84         /* Setup the signal pipe */
  85         udhcp_sp_setup();
  86
  87         timeout_end = time(0) + server_config.auto_time;
  88         while(1) { /* loop until universe collapses */
  89
  90                 if (server_socket < 0)
  91                         if ((server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface)) < 0) {
  92                                 LOG(LOG_ERR, "FATAL: couldn't create server socket, %m");
  93                                 return 2;
  94                         }
  95
  96                 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
  97                 if (server_config.auto_time) {
  98                         tv.tv_sec = timeout_end - time(0);
  99                         tv.tv_usec = 0;
 100                 }
 101                 if (!server_config.auto_time || tv.tv_sec > 0) {
 102                         retval = select(max_sock + 1, &rfds, NULL, NULL,
 103                                         server_config.auto_time ? &tv : NULL);
 104                 } else retval = 0; /* If we already timed out, fall through */
 105
 106                 if (retval == 0) {
 107                         write_leases();
 108                         timeout_end = time(0) + server_config.auto_time;
 109                         continue;
 110                 } else if (retval < 0 && errno != EINTR) {
 111                         DEBUG(LOG_INFO, "error on select");
 112                         continue;
 113                 }
 114
 115                 switch (udhcp_sp_read(&rfds)) {
 116                 case SIGUSR1:
 117                         LOG(LOG_INFO, "Received a SIGUSR1");
 118                         write_leases();
 119                         /* why not just reset the timeout, eh */
 120                         timeout_end = time(0) + server_config.auto_time;
 121                         continue;
 122                 case SIGTERM:
 123                         LOG(LOG_INFO, "Received a SIGTERM");
 124                         return 0;
 125                 case 0: break;          /* no signal */
 126                 default: continue;      /* signal or error (probably EINTR) */
 127                 }
 128
 129                 if ((bytes = udhcp_get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */
 130                         if (bytes == -1 && errno != EINTR) {
 131                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 132                                 close(server_socket);
 133                                 server_socket = -1;
 134                         }
 135                         continue;
 136                 }
 137
 138                 if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 139                         DEBUG(LOG_ERR, "couldn't get option from packet, ignoring");
 140                         continue;
 141                 }
 142
 143                 /* Look for a static lease */
 144                 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
 145
 146                 if(static_lease_ip)
 147                 {
 148                         printf("Found static lease: %x\n", static_lease_ip);
 149
 150                         memcpy(&static_lease.chaddr, &packet.chaddr, 16);
 151                         static_lease.yiaddr = static_lease_ip;
 152                         static_lease.expires = 0;
 153
 154                         lease = &static_lease;
 155
 156                 }
 157                 else
 158                 {
 159                 lease = find_lease_by_chaddr(packet.chaddr);
 160                 }
 161
 162                 switch (state[0]) {
 163                 case DHCPDISCOVER:
 164                         DEBUG(LOG_INFO,"received DISCOVER");
 165
 166                         if (sendOffer(&packet) < 0) {
 167                                 LOG(LOG_ERR, "send OFFER failed");
 168                         }
 169                         break;
 170                 case DHCPREQUEST:
 171                         DEBUG(LOG_INFO, "received REQUEST");
 172
 173                         requested = get_option(&packet, DHCP_REQUESTED_IP);
 174                         server_id = get_option(&packet, DHCP_SERVER_ID);
 175
 176                         if (requested) memcpy(&requested_align, requested, 4);
 177                         if (server_id) memcpy(&server_id_align, server_id, 4);
 178
 179                         if (lease) {
 180                                 if (server_id) {
 181                                         /* SELECTING State */
 182                                         DEBUG(LOG_INFO, "server_id = %08x", ntohl(server_id_align));
 183                                         if (server_id_align == server_config.server && requested &&
 184                                             requested_align == lease->yiaddr) {
 185                                                 sendACK(&packet, lease->yiaddr);
 186                                         }
 187                                 } else {
 188                                         if (requested) {
 189                                                 /* INIT-REBOOT State */
 190                                                 if (lease->yiaddr == requested_align)
 191                                                         sendACK(&packet, lease->yiaddr);
 192                                                 else sendNAK(&packet);
 193                                         } else {
 194                                                 /* RENEWING or REBINDING State */
 195                                                 if (lease->yiaddr == packet.ciaddr)
 196                                                         sendACK(&packet, lease->yiaddr);
 197                                                 else {
 198                                                         /* don't know what to do!!!! */
 199                                                         sendNAK(&packet);
 200                                                 }
 201                                         }
 202                                 }
 203
 204                         /* what to do if we have no record of the client */
 205                         } else if (server_id) {
 206                                 /* SELECTING State */
 207
 208                         } else if (requested) {
 209                                 /* INIT-REBOOT State */
 210                                 if ((lease = find_lease_by_yiaddr(requested_align))) {
 211                                         if (lease_expired(lease)) {
 212                                                 /* probably best if we drop this lease */
 213                                                 memset(lease->chaddr, 0, 16);
 214                                         /* make some contention for this address */
 215                                         } else sendNAK(&packet);
 216                                 } else if (requested_align < server_config.start ||
 217                                            requested_align > server_config.end) {
 218                                         sendNAK(&packet);
 219                                 } /* else remain silent */
 220
 221                         } else {
 222                                  /* RENEWING or REBINDING State */
 223                         }
 224                         break;
 225                 case DHCPDECLINE:
 226                         DEBUG(LOG_INFO,"received DECLINE");
 227                         if (lease) {
 228                                 memset(lease->chaddr, 0, 16);
 229                                 lease->expires = time(0) + server_config.decline_time;
 230                         }
 231                         break;
 232                 case DHCPRELEASE:
 233                         DEBUG(LOG_INFO,"received RELEASE");
 234                         if (lease) lease->expires = time(0);
 235                         break;
 236                 case DHCPINFORM:
 237                         DEBUG(LOG_INFO,"received INFORM");
 238                         send_inform(&packet);
 239                         break;
 240                 default:
 241                         LOG(LOG_WARNING, "unsupported DHCP message (%02x) -- ignoring", state[0]);
 242                 }
 243         }
 244
 245         return 0;
 246 }
 247