networking/udhcp/dhcpd.c

/* vi: set sw=4 ts=4: */
/* dhcpd.c
 *
 * udhcp Server
 * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
 *			Chris Trew <ctrew@moreton.com.au>
 *
 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include <syslog.h>
#include "common.h"
#include "dhcpc.h"
#include "dhcpd.h"
#include "options.h"


/* globals */
struct dyn_lease *g_leases;
/* struct server_config_t server_config is in bb_common_bufsiz1 */


int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int udhcpd_main(int argc UNUSED_PARAM, char **argv)
{
	fd_set rfds;
	int server_socket = -1, retval, max_sock;
	struct dhcp_packet packet;
	uint8_t *state;
	uint32_t static_lease_ip;
	unsigned timeout_end;
	unsigned num_ips;
	unsigned opt;
	struct option_set *option;
	struct dyn_lease *lease, fake_lease;
	IF_FEATURE_UDHCP_PORT(char *str_P;)

#if ENABLE_FEATURE_UDHCP_PORT
	SERVER_PORT = 67;
	CLIENT_PORT = 68;
#endif

#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
	opt_complementary = "vv";
#endif
	opt = getopt32(argv, "fSv"
		IF_FEATURE_UDHCP_PORT("P:", &str_P)
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
		, &dhcp_verbose
#endif
		);
	argv += optind;
	if (!(opt & 1)) { /* no -f */
		bb_daemonize_or_rexec(0, argv);
		logmode = LOGMODE_NONE;
	}
	if (opt & 2) { /* -S */
		openlog(applet_name, LOG_PID, LOG_DAEMON);
		logmode |= LOGMODE_SYSLOG;
	}
#if ENABLE_FEATURE_UDHCP_PORT
	if (opt & 8) { /* -P */
		SERVER_PORT = xatou16(str_P);
		CLIENT_PORT = SERVER_PORT + 1;
	}
#endif
	/* Would rather not do read_config before daemonization -
	 * otherwise NOMMU machines will parse config twice */
	read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);

	/* Make sure fd 0,1,2 are open */
	bb_sanitize_stdio();
	/* Equivalent of doing a fflush after every \n */
	setlinebuf(stdout);

	/* Create pidfile */
	write_pidfile(server_config.pidfile);
	/* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */

	bb_info_msg("%s (v"BB_VER") started", applet_name);

	option = find_option(server_config.options, DHCP_LEASE_TIME);
	server_config.max_lease_sec = LEASE_TIME;
	if (option) {
		move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
		server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
	}

	/* Sanity check */
	num_ips = server_config.end_ip - server_config.start_ip + 1;
	if (server_config.max_leases > num_ips) {
		bb_error_msg("max_leases=%u is too big, setting to %u",
			(unsigned)server_config.max_leases, num_ips);
		server_config.max_leases = num_ips;
	}

	g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0]));
	read_leases(server_config.lease_file);

	if (udhcp_read_interface(server_config.interface,
			&server_config.ifindex,
			&server_config.server_nip,
			server_config.server_mac)
	) {
		retval = 1;
		goto ret;
	}

	/* Setup the signal pipe */
	udhcp_sp_setup();

	timeout_end = monotonic_sec() + server_config.auto_time;
	while (1) { /* loop until universe collapses */
		int bytes;
		struct timeval tv;

		if (server_socket < 0) {
			server_socket = udhcp_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 - monotonic_sec();
			tv.tv_usec = 0;
		}
		retval = 0;
		if (!server_config.auto_time || tv.tv_sec > 0) {
			retval = select(max_sock + 1, &rfds, NULL, NULL,
					server_config.auto_time ? &tv : NULL);
		}
		if (retval == 0) {
			write_leases();
			timeout_end = monotonic_sec() + server_config.auto_time;
			continue;
		}
		if (retval < 0 && errno != EINTR) {
			log1("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 = monotonic_sec() + server_config.auto_time;
			continue;
		case SIGTERM:
			bb_info_msg("Received a SIGTERM");
			goto ret0;
		case 0:	/* no signal: read a packet */
			break;
		default: /* signal or error (probably EINTR): back to select */
			continue;
		}

		bytes = udhcp_recv_kernel_packet(&packet, server_socket);
		if (bytes < 0) {
			/* bytes can also be -2 ("bad packet data") */
			if (bytes == -1 && errno != EINTR) {
				log1("Read error: %s, reopening socket", strerror(errno));
				close(server_socket);
				server_socket = -1;
			}
			continue;
		}

		if (packet.hlen != 6) {
			bb_error_msg("MAC length != 6, ignoring packet");
			continue;
		}

		state = get_option(&packet, DHCP_MESSAGE_TYPE);
		if (state == NULL) {
			bb_error_msg("no message type option, ignoring packet");
			continue;
		}

		/* Look for a static lease */
		static_lease_ip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
		if (static_lease_ip) {
			bb_info_msg("Found static lease: %x", static_lease_ip);

			memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
			fake_lease.lease_nip = static_lease_ip;
			fake_lease.expires = 0;

			lease = &fake_lease;
		} else {
			lease = find_lease_by_mac(packet.chaddr);
		}

		switch (state[0]) {
		case DHCPDISCOVER:
			log1("Received DISCOVER");

			if (send_offer(&packet) < 0) {
				bb_error_msg("send OFFER failed");
			}
			break;
		case DHCPREQUEST: {
			uint8_t *server_id_opt, *requested_opt;
			uint32_t server_id_net = server_id_net; /* for compiler */
			uint32_t requested_nip = requested_nip; /* for compiler */

			log1("Received REQUEST");

			requested_opt = get_option(&packet, DHCP_REQUESTED_IP);
			server_id_opt = get_option(&packet, DHCP_SERVER_ID);
			if (requested_opt)
				move_from_unaligned32(requested_nip, requested_opt);
			if (server_id_opt)
				move_from_unaligned32(server_id_net, server_id_opt);

			if (lease) {
				if (server_id_opt) {
					/* SELECTING State */
					if (server_id_net == server_config.server_nip
					 && requested_opt
					 && requested_nip == lease->lease_nip
					) {
						send_ACK(&packet, lease->lease_nip);
					}
				} else if (requested_opt) {
					/* INIT-REBOOT State */
					if (lease->lease_nip == requested_nip)
						send_ACK(&packet, lease->lease_nip);
					else
						send_NAK(&packet);
				} else if (lease->lease_nip == packet.ciaddr) {
					/* RENEWING or REBINDING State */
					send_ACK(&packet, lease->lease_nip);
				} else { /* don't know what to do!!!! */
					send_NAK(&packet);
				}

			/* what to do if we have no record of the client */
			} else if (server_id_opt) {
				/* SELECTING State */

			} else if (requested_opt) {
				/* INIT-REBOOT State */
				lease = find_lease_by_nip(requested_nip);
				if (lease) {
					if (is_expired_lease(lease)) {
						/* probably best if we drop this lease */
						memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
					} else {
						/* make some contention for this address */
						send_NAK(&packet);
					}
				} else {
					uint32_t r = ntohl(requested_nip);
					if (r < server_config.start_ip
				         || r > server_config.end_ip
					) {
						send_NAK(&packet);
					}
					/* else remain silent */
				}

			} else {
				/* RENEWING or REBINDING State */
			}
			break;
		}
		case DHCPDECLINE:
			log1("Received DECLINE");
			if (lease) {
				memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
				lease->expires = time(NULL) + server_config.decline_time;
			}
			break;
		case DHCPRELEASE:
			log1("Received RELEASE");
			if (lease)
				lease->expires = time(NULL);
			break;
		case DHCPINFORM:
			log1("Received INFORM");
			send_inform(&packet);
			break;
		default:
			bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
		}
	}
 ret0:
	retval = 0;
 ret:
	/*if (server_config.pidfile) - server_config.pidfile is never NULL */
		remove_pidfile(server_config.pidfile);
	return retval;
}
1	niro	532	/* 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	niro	816	#include <syslog.h>
14	niro	532	#include "common.h"
15	niro	816	#include "dhcpc.h"
16	niro	532	#include "dhcpd.h"
17			#include "options.h"
18
19
20			/* globals */
21	niro	984	struct dyn_lease *g_leases;
22	niro	816	/* struct server_config_t server_config is in bb_common_bufsiz1 */
23	niro	532
24
25	niro	816	int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
26			int udhcpd_main(int argc UNUSED_PARAM, char **argv)
27	niro	532	{
28			fd_set rfds;
29	niro	984	int server_socket = -1, retval, max_sock;
30			struct dhcp_packet packet;
31			uint8_t *state;
32			uint32_t static_lease_ip;
33	niro	816	unsigned timeout_end;
34			unsigned num_ips;
35			unsigned opt;
36	niro	532	struct option_set *option;
37	niro	984	struct dyn_lease *lease, fake_lease;
38			IF_FEATURE_UDHCP_PORT(char *str_P;)
39	niro	532
40	niro	816	#if ENABLE_FEATURE_UDHCP_PORT
41			SERVER_PORT = 67;
42			CLIENT_PORT = 68;
43			#endif
44	niro	532
45	niro	984	#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
46			opt_complementary = "vv";
47			#endif
48			opt = getopt32(argv, "fSv"
49			IF_FEATURE_UDHCP_PORT("P:", &str_P)
50			#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
51			, &dhcp_verbose
52			#endif
53			);
54	niro	816	argv += optind;
55			if (!(opt & 1)) { /* no -f */
56			bb_daemonize_or_rexec(0, argv);
57	niro	984	logmode = LOGMODE_NONE;
58	niro	816	}
59			if (opt & 2) { /* -S */
60	niro	984	openlog(applet_name, LOG_PID, LOG_DAEMON);
61	niro	816	logmode \|= LOGMODE_SYSLOG;
62			}
63			#if ENABLE_FEATURE_UDHCP_PORT
64	niro	984	if (opt & 8) { /* -P */
65	niro	816	SERVER_PORT = xatou16(str_P);
66			CLIENT_PORT = SERVER_PORT + 1;
67			}
68			#endif
69			/* Would rather not do read_config before daemonization -
70			* otherwise NOMMU machines will parse config twice */
71			read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
72
73			/* Make sure fd 0,1,2 are open */
74			bb_sanitize_stdio();
75			/* Equivalent of doing a fflush after every \n */
76			setlinebuf(stdout);
77
78			/* Create pidfile */
79			write_pidfile(server_config.pidfile);
80	niro	984	/* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */
81	niro	816
82			bb_info_msg("%s (v"BB_VER") started", applet_name);
83
84			option = find_option(server_config.options, DHCP_LEASE_TIME);
85	niro	984	server_config.max_lease_sec = LEASE_TIME;
86	niro	816	if (option) {
87	niro	984	move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
88			server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
89	niro	532	}
90
91			/* Sanity check */
92	niro	816	num_ips = server_config.end_ip - server_config.start_ip + 1;
93	niro	532	if (server_config.max_leases > num_ips) {
94	niro	816	bb_error_msg("max_leases=%u is too big, setting to %u",
95			(unsigned)server_config.max_leases, num_ips);
96	niro	532	server_config.max_leases = num_ips;
97			}
98
99	niro	984	g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0]));
100	niro	532	read_leases(server_config.lease_file);
101
102	niro	984	if (udhcp_read_interface(server_config.interface,
103			&server_config.ifindex,
104			&server_config.server_nip,
105			server_config.server_mac)
106			) {
107	niro	816	retval = 1;
108			goto ret;
109			}
110	niro	532
111			/* Setup the signal pipe */
112			udhcp_sp_setup();
113
114	niro	816	timeout_end = monotonic_sec() + server_config.auto_time;
115	niro	532	while (1) { /* loop until universe collapses */
116	niro	984	int bytes;
117			struct timeval tv;
118	niro	532
119			if (server_socket < 0) {
120	niro	816	server_socket = udhcp_listen_socket(/INADDR_ANY,/ SERVER_PORT,
121			server_config.interface);
122	niro	532	}
123
124			max_sock = udhcp_sp_fd_set(&rfds, server_socket);
125			if (server_config.auto_time) {
126	niro	816	tv.tv_sec = timeout_end - monotonic_sec();
127	niro	532	tv.tv_usec = 0;
128			}
129	niro	816	retval = 0;
130	niro	532	if (!server_config.auto_time \|\| tv.tv_sec > 0) {
131			retval = select(max_sock + 1, &rfds, NULL, NULL,
132			server_config.auto_time ? &tv : NULL);
133	niro	816	}
134	niro	532	if (retval == 0) {
135			write_leases();
136	niro	816	timeout_end = monotonic_sec() + server_config.auto_time;
137	niro	532	continue;
138	niro	816	}
139			if (retval < 0 && errno != EINTR) {
140	niro	984	log1("Error on select");
141	niro	532	continue;
142			}
143
144			switch (udhcp_sp_read(&rfds)) {
145			case SIGUSR1:
146			bb_info_msg("Received a SIGUSR1");
147			write_leases();
148			/* why not just reset the timeout, eh */
149	niro	816	timeout_end = monotonic_sec() + server_config.auto_time;
150	niro	532	continue;
151			case SIGTERM:
152			bb_info_msg("Received a SIGTERM");
153	niro	816	goto ret0;
154	niro	984	case 0: /* no signal: read a packet */
155			break;
156			default: /* signal or error (probably EINTR): back to select */
157			continue;
158	niro	532	}
159
160	niro	984	bytes = udhcp_recv_kernel_packet(&packet, server_socket);
161	niro	816	if (bytes < 0) {
162	niro	984	/* bytes can also be -2 ("bad packet data") */
163	niro	532	if (bytes == -1 && errno != EINTR) {
164	niro	984	log1("Read error: %s, reopening socket", strerror(errno));
165	niro	532	close(server_socket);
166			server_socket = -1;
167			}
168			continue;
169			}
170
171	niro	984	if (packet.hlen != 6) {
172			bb_error_msg("MAC length != 6, ignoring packet");
173			continue;
174			}
175
176	niro	816	state = get_option(&packet, DHCP_MESSAGE_TYPE);
177			if (state == NULL) {
178	niro	984	bb_error_msg("no message type option, ignoring packet");
179	niro	532	continue;
180			}
181
182			/* Look for a static lease */
183	niro	984	static_lease_ip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
184	niro	532	if (static_lease_ip) {
185			bb_info_msg("Found static lease: %x", static_lease_ip);
186
187	niro	984	memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
188			fake_lease.lease_nip = static_lease_ip;
189			fake_lease.expires = 0;
190	niro	532
191	niro	984	lease = &fake_lease;
192	niro	532	} else {
193	niro	984	lease = find_lease_by_mac(packet.chaddr);
194	niro	532	}
195
196			switch (state[0]) {
197			case DHCPDISCOVER:
198	niro	984	log1("Received DISCOVER");
199	niro	532
200	niro	816	if (send_offer(&packet) < 0) {
201	niro	532	bb_error_msg("send OFFER failed");
202			}
203			break;
204	niro	984	case DHCPREQUEST: {
205			uint8_t server_id_opt, requested_opt;
206			uint32_t server_id_net = server_id_net; /* for compiler */
207			uint32_t requested_nip = requested_nip; /* for compiler */
208	niro	532
209	niro	984	log1("Received REQUEST");
210	niro	532
211	niro	984	requested_opt = get_option(&packet, DHCP_REQUESTED_IP);
212			server_id_opt = get_option(&packet, DHCP_SERVER_ID);
213			if (requested_opt)
214			move_from_unaligned32(requested_nip, requested_opt);
215			if (server_id_opt)
216			move_from_unaligned32(server_id_net, server_id_opt);
217	niro	532
218			if (lease) {
219	niro	984	if (server_id_opt) {
220	niro	532	/* SELECTING State */
221	niro	984	if (server_id_net == server_config.server_nip
222			&& requested_opt
223			&& requested_nip == lease->lease_nip
224	niro	816	) {
225	niro	984	send_ACK(&packet, lease->lease_nip);
226	niro	532	}
227	niro	984	} else if (requested_opt) {
228	niro	816	/* INIT-REBOOT State */
229	niro	984	if (lease->lease_nip == requested_nip)
230			send_ACK(&packet, lease->lease_nip);
231	niro	816	else
232			send_NAK(&packet);
233	niro	984	} else if (lease->lease_nip == packet.ciaddr) {
234	niro	816	/* RENEWING or REBINDING State */
235	niro	984	send_ACK(&packet, lease->lease_nip);
236	niro	816	} else { /* don't know what to do!!!! */
237			send_NAK(&packet);
238	niro	532	}
239
240			/* what to do if we have no record of the client */
241	niro	984	} else if (server_id_opt) {
242	niro	532	/* SELECTING State */
243
244	niro	984	} else if (requested_opt) {
245	niro	532	/* INIT-REBOOT State */
246	niro	984	lease = find_lease_by_nip(requested_nip);
247	niro	816	if (lease) {
248	niro	984	if (is_expired_lease(lease)) {
249	niro	532	/* probably best if we drop this lease */
250	niro	984	memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
251			} else {
252			/* make some contention for this address */
253	niro	816	send_NAK(&packet);
254	niro	984	}
255	niro	816	} else {
256	niro	984	uint32_t r = ntohl(requested_nip);
257	niro	816	if (r < server_config.start_ip
258			\|\| r > server_config.end_ip
259			) {
260			send_NAK(&packet);
261			}
262			/* else remain silent */
263			}
264	niro	532
265			} else {
266	niro	816	/* RENEWING or REBINDING State */
267	niro	532	}
268			break;
269	niro	984	}
270	niro	532	case DHCPDECLINE:
271	niro	984	log1("Received DECLINE");
272	niro	532	if (lease) {
273	niro	984	memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
274			lease->expires = time(NULL) + server_config.decline_time;
275	niro	532	}
276			break;
277			case DHCPRELEASE:
278	niro	984	log1("Received RELEASE");
279	niro	816	if (lease)
280	niro	984	lease->expires = time(NULL);
281	niro	532	break;
282			case DHCPINFORM:
283	niro	984	log1("Received INFORM");
284	niro	532	send_inform(&packet);
285			break;
286			default:
287			bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
288			}
289			}
290	niro	816	ret0:
291			retval = 0;
292			ret:
293			/if (server_config.pidfile) - server_config.pidfile is never NULL /
294			remove_pidfile(server_config.pidfile);
295			return retval;
296	niro	532	}