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