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