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 "dhcpd.h" 16#include "options.h" 17 18 19/* globals */ 20struct dhcpOfferedAddr *leases; 21struct server_config_t server_config; 22 23 24int udhcpd_main(int argc, char **argv); 25int udhcpd_main(int argc, char **argv) 26{ 27 fd_set rfds; 28 struct timeval tv; 29 int server_socket = -1, bytes, retval, max_sock; 30 struct dhcpMessage packet; 31 uint8_t *state, *server_id, *requested; 32 uint32_t server_id_align, requested_align, static_lease_ip; 33 unsigned timeout_end; 34 unsigned num_ips; 35 unsigned opt; 36 struct option_set *option; 37 struct dhcpOfferedAddr *lease, static_lease; 38 39 opt = getopt32(argv, "fS"); 40 argv += optind; 41 42 if (!(opt & 1)) { /* no -f */ 43 bb_daemonize_or_rexec(0, argv); 44 logmode &= ~LOGMODE_STDIO; 45 } 46 47 if (opt & 2) { /* -S */ 48 openlog(applet_name, LOG_PID, LOG_LOCAL0); 49 logmode |= LOGMODE_SYSLOG; 50 } 51 52 /* Would rather not do read_config before daemonization - 53 * otherwise NOMMU machines will parse config twice */ 54 read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE); 55 56 /* Make sure fd 0,1,2 are open */ 57 bb_sanitize_stdio(); 58 /* Equivalent of doing a fflush after every \n */ 59 setlinebuf(stdout); 60 61 /* Create pidfile */ 62 write_pidfile(server_config.pidfile); 63 /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */ 64 65 bb_info_msg("%s (v%s) started", applet_name, BB_VER); 66 67 option = find_option(server_config.options, DHCP_LEASE_TIME); 68 server_config.lease = LEASE_TIME; 69 if (option) { 70 memcpy(&server_config.lease, option->data + 2, 4); 71 server_config.lease = ntohl(server_config.lease); 72 } 73 74 /* Sanity check */ 75 num_ips = server_config.end_ip - server_config.start_ip + 1; 76 if (server_config.max_leases > num_ips) { 77 bb_error_msg("max_leases=%u is too big, setting to %u", 78 (unsigned)server_config.max_leases, num_ips); 79 server_config.max_leases = num_ips; 80 } 81 82 leases = xzalloc(server_config.max_leases * sizeof(*leases)); 83 read_leases(server_config.lease_file); 84 85 if (read_interface(server_config.interface, &server_config.ifindex, 86 &server_config.server, server_config.arp)) { 87 retval = 1; 88 goto ret; 89 } 90 91 /* Setup the signal pipe */ 92 udhcp_sp_setup(); 93 94 timeout_end = monotonic_sec() + server_config.auto_time; 95 while (1) { /* loop until universe collapses */ 96 97 if (server_socket < 0) { 98 server_socket = listen_socket(/*INADDR_ANY,*/ SERVER_PORT, 99 server_config.interface); 100 } 101 102 max_sock = udhcp_sp_fd_set(&rfds, server_socket); 103 if (server_config.auto_time) { 104 tv.tv_sec = timeout_end - monotonic_sec(); 105 tv.tv_usec = 0; 106 } 107 retval = 0; 108 if (!server_config.auto_time || tv.tv_sec > 0) { 109 retval = select(max_sock + 1, &rfds, NULL, NULL, 110 server_config.auto_time ? &tv : NULL); 111 } 112 if (retval == 0) { 113 write_leases(); 114 timeout_end = monotonic_sec() + server_config.auto_time; 115 continue; 116 } 117 if (retval < 0 && errno != EINTR) { 118 DEBUG("error on select"); 119 continue; 120 } 121 122 switch (udhcp_sp_read(&rfds)) { 123 case SIGUSR1: 124 bb_info_msg("Received a SIGUSR1"); 125 write_leases(); 126 /* why not just reset the timeout, eh */ 127 timeout_end = monotonic_sec() + server_config.auto_time; 128 continue; 129 case SIGTERM: 130 bb_info_msg("Received a SIGTERM"); 131 goto ret0; 132 case 0: break; /* no signal */ 133 default: continue; /* signal or error (probably EINTR) */ 134 } 135 136 bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */ 137 if (bytes < 0) { 138 if (bytes == -1 && errno != EINTR) { 139 DEBUG("error on read, %s, reopening socket", strerror(errno)); 140 close(server_socket); 141 server_socket = -1; 142 } 143 continue; 144 } 145 146 state = get_option(&packet, DHCP_MESSAGE_TYPE); 147 if (state == NULL) { 148 bb_error_msg("cannot get option from packet, ignoring"); 149 continue; 150 } 151 152 /* Look for a static lease */ 153 static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr); 154 155 if (static_lease_ip) { 156 bb_info_msg("Found static lease: %x", static_lease_ip); 157 158 memcpy(&static_lease.chaddr, &packet.chaddr, 16); 159 static_lease.yiaddr = static_lease_ip; 160 static_lease.expires = 0; 161 162 lease = &static_lease; 163 } else { 164 lease = find_lease_by_chaddr(packet.chaddr); 165 } 166 167 switch (state[0]) { 168 case DHCPDISCOVER: 169 DEBUG("Received DISCOVER"); 170 171 if (sendOffer(&packet) < 0) { 172 bb_error_msg("send OFFER failed"); 173 } 174 break; 175 case DHCPREQUEST: 176 DEBUG("received REQUEST"); 177 178 requested = get_option(&packet, DHCP_REQUESTED_IP); 179 server_id = get_option(&packet, DHCP_SERVER_ID); 180 181 if (requested) memcpy(&requested_align, requested, 4); 182 if (server_id) memcpy(&server_id_align, server_id, 4); 183 184 if (lease) { 185 if (server_id) { 186 /* SELECTING State */ 187 DEBUG("server_id = %08x", ntohl(server_id_align)); 188 if (server_id_align == server_config.server && requested 189 && requested_align == lease->yiaddr 190 ) { 191 sendACK(&packet, lease->yiaddr); 192 } 193 } else if (requested) { 194 /* INIT-REBOOT State */ 195 if (lease->yiaddr == requested_align) 196 sendACK(&packet, lease->yiaddr); 197 else 198 sendNAK(&packet); 199 } else if (lease->yiaddr == packet.ciaddr) { 200 /* RENEWING or REBINDING State */ 201 sendACK(&packet, lease->yiaddr); 202 } else { 203 /* don't know what to do!!!! */ 204 sendNAK(&packet); 205 } 206 207 /* what to do if we have no record of the client */ 208 } else if (server_id) { 209 /* SELECTING State */ 210 211 } else if (requested) { 212 /* INIT-REBOOT State */ 213 lease = find_lease_by_yiaddr(requested_align); 214 if (lease) { 215 if (lease_expired(lease)) { 216 /* probably best if we drop this lease */ 217 memset(lease->chaddr, 0, 16); 218 /* make some contention for this address */ 219 } else 220 sendNAK(&packet); 221 } else { 222 uint32_t r = ntohl(requested_align); 223 if (r < server_config.start_ip 224 || r > server_config.end_ip 225 ) { 226 sendNAK(&packet); 227 } 228 /* else remain silent */ 229 } 230 231 } else { 232 /* RENEWING or REBINDING State */ 233 } 234 break; 235 case DHCPDECLINE: 236 DEBUG("Received DECLINE"); 237 if (lease) { 238 memset(lease->chaddr, 0, 16); 239 lease->expires = time(0) + server_config.decline_time; 240 } 241 break; 242 case DHCPRELEASE: 243 DEBUG("Received RELEASE"); 244 if (lease) 245 lease->expires = time(0); 246 break; 247 case DHCPINFORM: 248 DEBUG("Received INFORM"); 249 send_inform(&packet); 250 break; 251 default: 252 bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]); 253 } 254 } 255 ret0: 256 retval = 0; 257 ret: 258 /*if (server_config.pidfile) - server_config.pidfile is never NULL */ 259 remove_pidfile(server_config.pidfile); 260 return retval; 261} 262