/* vi: set sw=4 ts=4: */ /* dhcpd.c * * udhcp Server * Copyright (C) 1999 Matthew Ramsay * Chris Trew * * Rewrite by Russ Dill July 2001 * * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ #include "common.h" #include "dhcpd.h" #include "options.h" /* globals */ struct dhcpOfferedAddr *leases; struct server_config_t server_config; int udhcpd_main(int argc, char *argv[]); int udhcpd_main(int argc, char *argv[]) { fd_set rfds; struct timeval tv; int server_socket = -1, bytes, retval, max_sock; struct dhcpMessage packet; uint8_t *state, *server_id, *requested; uint32_t server_id_align, requested_align, static_lease_ip; unsigned long timeout_end, num_ips; struct option_set *option; struct dhcpOfferedAddr *lease, static_lease; read_config(argc < 2 ? DHCPD_CONF_FILE : argv[1]); /* Start the log, sanitize fd's, and write a pid file */ udhcp_start_log_and_pid(server_config.pidfile); if ((option = find_option(server_config.options, DHCP_LEASE_TIME))) { memcpy(&server_config.lease, option->data + 2, 4); server_config.lease = ntohl(server_config.lease); } else server_config.lease = LEASE_TIME; /* Sanity check */ num_ips = ntohl(server_config.end) - ntohl(server_config.start) + 1; if (server_config.max_leases > num_ips) { bb_error_msg("max_leases value (%lu) not sane, " "setting to %lu instead", server_config.max_leases, num_ips); server_config.max_leases = num_ips; } leases = xzalloc(server_config.max_leases * sizeof(struct dhcpOfferedAddr)); read_leases(server_config.lease_file); if (read_interface(server_config.interface, &server_config.ifindex, &server_config.server, server_config.arp) < 0) return 1; if (!ENABLE_FEATURE_UDHCP_DEBUG) udhcp_background(server_config.pidfile); /* hold lock during fork. */ /* Setup the signal pipe */ udhcp_sp_setup(); timeout_end = time(0) + server_config.auto_time; while (1) { /* loop until universe collapses */ if (server_socket < 0) { server_socket = listen_socket(INADDR_ANY, SERVER_PORT, server_config.interface); } max_sock = udhcp_sp_fd_set(&rfds, server_socket); if (server_config.auto_time) { tv.tv_sec = timeout_end - time(0); tv.tv_usec = 0; } if (!server_config.auto_time || tv.tv_sec > 0) { retval = select(max_sock + 1, &rfds, NULL, NULL, server_config.auto_time ? &tv : NULL); } else retval = 0; /* If we already timed out, fall through */ if (retval == 0) { write_leases(); timeout_end = time(0) + server_config.auto_time; continue; } else if (retval < 0 && errno != EINTR) { DEBUG("error on select"); continue; } switch (udhcp_sp_read(&rfds)) { case SIGUSR1: bb_info_msg("Received a SIGUSR1"); write_leases(); /* why not just reset the timeout, eh */ timeout_end = time(0) + server_config.auto_time; continue; case SIGTERM: bb_info_msg("Received a SIGTERM"); return 0; case 0: break; /* no signal */ default: continue; /* signal or error (probably EINTR) */ } if ((bytes = udhcp_get_packet(&packet, server_socket)) < 0) { /* this waits for a packet - idle */ if (bytes == -1 && errno != EINTR) { DEBUG("error on read, %s, reopening socket", strerror(errno)); close(server_socket); server_socket = -1; } continue; } if ((state = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) { bb_error_msg("cannot get option from packet, ignoring"); continue; } /* Look for a static lease */ static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr); if (static_lease_ip) { bb_info_msg("Found static lease: %x", static_lease_ip); memcpy(&static_lease.chaddr, &packet.chaddr, 16); static_lease.yiaddr = static_lease_ip; static_lease.expires = 0; lease = &static_lease; } else { lease = find_lease_by_chaddr(packet.chaddr); } switch (state[0]) { case DHCPDISCOVER: DEBUG("Received DISCOVER"); if (sendOffer(&packet) < 0) { bb_error_msg("send OFFER failed"); } break; case DHCPREQUEST: DEBUG("received REQUEST"); requested = get_option(&packet, DHCP_REQUESTED_IP); server_id = get_option(&packet, DHCP_SERVER_ID); if (requested) memcpy(&requested_align, requested, 4); if (server_id) memcpy(&server_id_align, server_id, 4); if (lease) { if (server_id) { /* SELECTING State */ DEBUG("server_id = %08x", ntohl(server_id_align)); if (server_id_align == server_config.server && requested && requested_align == lease->yiaddr) { sendACK(&packet, lease->yiaddr); } } else { if (requested) { /* INIT-REBOOT State */ if (lease->yiaddr == requested_align) sendACK(&packet, lease->yiaddr); else sendNAK(&packet); } else { /* RENEWING or REBINDING State */ if (lease->yiaddr == packet.ciaddr) sendACK(&packet, lease->yiaddr); else { /* don't know what to do!!!! */ sendNAK(&packet); } } } /* what to do if we have no record of the client */ } else if (server_id) { /* SELECTING State */ } else if (requested) { /* INIT-REBOOT State */ if ((lease = find_lease_by_yiaddr(requested_align))) { if (lease_expired(lease)) { /* probably best if we drop this lease */ memset(lease->chaddr, 0, 16); /* make some contention for this address */ } else sendNAK(&packet); } else if (requested_align < server_config.start || requested_align > server_config.end) { sendNAK(&packet); } /* else remain silent */ } else { /* RENEWING or REBINDING State */ } break; case DHCPDECLINE: DEBUG("Received DECLINE"); if (lease) { memset(lease->chaddr, 0, 16); lease->expires = time(0) + server_config.decline_time; } break; case DHCPRELEASE: DEBUG("Received RELEASE"); if (lease) lease->expires = time(0); break; case DHCPINFORM: DEBUG("Received INFORM"); send_inform(&packet); break; default: bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]); } } return 0; }