1/* socket.c
2
3   BSD socket interface code... */
4
5/*
6 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
7 * Copyright (c) 1995-2003 by Internet Software Consortium
8 *
9 * Permission to use, copy, modify, and distribute this software for any
10 * purpose with or without fee is hereby granted, provided that the above
11 * copyright notice and this permission notice appear in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
14 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
16 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
19 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 *
21 *   Internet Systems Consortium, Inc.
22 *   950 Charter Street
23 *   Redwood City, CA 94063
24 *   <info@isc.org>
25 *   http://www.isc.org/
26 *
27 * This software has been written for Internet Systems Consortium
28 * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
29 * To learn more about Internet Systems Consortium, see
30 * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
31 * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
32 * ``http://www.nominum.com''.
33 */
34
35/* SO_BINDTODEVICE support added by Elliot Poger (poger@leland.stanford.edu).
36 * This sockopt allows a socket to be bound to a particular interface,
37 * thus enabling the use of DHCPD on a multihomed host.
38 * If SO_BINDTODEVICE is defined in your system header files, the use of
39 * this sockopt will be automatically enabled.
40 * I have implemented it under Linux; other systems should be doable also.
41 */
42
43#ifndef lint
44static char copyright[] =
45"$Id: socket.c,v 1.7 2005/08/11 17:13:21 drochner Exp $ Copyright (c) 2004 Internet Systems Consortium.  All rights reserved.\n";
46#endif /* not lint */
47
48#include "dhcpd.h"
49
50#ifdef USE_SOCKET_FALLBACK
51# if !defined (USE_SOCKET_SEND)
52#  define if_register_send if_register_fallback
53#  define send_packet send_fallback
54#  define if_reinitialize_send if_reinitialize_fallback
55# endif
56#endif
57
58#if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
59#if 0
60#ifndef USE_SOCKET_RECEIVE
61static int once = 0;
62#endif
63#endif
64#endif
65
66/* Reinitializes the specified interface after an address change.   This
67   is not required for packet-filter APIs. */
68
69#if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
70void if_reinitialize_send (info)
71	struct interface_info *info;
72{
73#if 0
74#ifndef USE_SOCKET_RECEIVE
75	once = 0;
76	close (info -> wfdesc);
77#endif
78	if_register_send (info);
79#endif
80}
81#endif
82
83#ifdef USE_SOCKET_RECEIVE
84void if_reinitialize_receive (info)
85	struct interface_info *info;
86{
87#if 0
88	once = 0;
89	close (info -> rfdesc);
90	if_register_receive (info);
91#endif
92}
93#endif
94
95#if defined (USE_SOCKET_SEND) || \
96	defined (USE_SOCKET_RECEIVE) || \
97		defined (USE_SOCKET_FALLBACK)
98/* Generic interface registration routine... */
99int if_register_socket (info)
100	struct interface_info *info;
101{
102	struct sockaddr_in name;
103	int sock;
104	int flag;
105#ifndef SMALL
106	char *buf;
107	char *policy = "out bypass";
108#endif
109
110#if !defined (HAVE_SO_BINDTODEVICE) && !defined (USE_FALLBACK)
111	/* Make sure only one interface is registered. */
112	if (once)
113		log_fatal ("The standard socket API can only support %s",
114		       "hosts with a single network interface.");
115	once = 1;
116#endif
117
118	memset (&name, 0, sizeof (name));
119	/* Set up the address we're going to bind to. */
120	name.sin_family = AF_INET;
121	name.sin_port = local_port;
122	name.sin_addr = local_address;
123
124	/* Make a socket... */
125	if ((sock = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
126		log_fatal ("Can't create dhcp socket: %m");
127
128	/* Set the REUSEADDR option so that we don't fail to start if
129	   we're being restarted. */
130	flag = 1;
131	if (setsockopt (sock, SOL_SOCKET, SO_REUSEADDR,
132			(char *)&flag, sizeof flag) < 0)
133		log_fatal ("Can't set SO_REUSEADDR option on dhcp socket: %m");
134
135#ifndef SMALL
136	/* Set a per-socket IPsec policy to prevent encryption. */
137	buf = ipsec_set_policy(policy, strlen(policy));
138	if (setsockopt (sock, IPPROTO_IP, IP_IPSEC_POLICY, buf,
139	    ipsec_get_policylen(buf)) < 0 && errno != ENOPROTOOPT)
140		log_fatal ("Can't set IPsec policy on dhcp socket: %m");
141	free (buf);
142#endif
143
144	/* Set the BROADCAST option so that we can broadcast DHCP responses.
145	   We shouldn't do this for fallback devices, and we can detect that
146	   a device is a fallback because it has no ifp structure. */
147	if (info -> ifp &&
148	    (setsockopt (sock, SOL_SOCKET, SO_BROADCAST,
149			 (char *)&flag, sizeof flag) < 0))
150		log_fatal ("Can't set SO_BROADCAST option on dhcp socket: %m");
151
152	/* Bind the socket to this interface's IP address. */
153	if (bind (sock, (struct sockaddr *)&name, sizeof name) < 0) {
154		log_error ("Can't bind to dhcp address: %m");
155		log_error ("Please make sure there is no other dhcp server");
156		log_error ("running and that there's no entry for dhcp or");
157		log_error ("bootp in /etc/inetd.conf.   Also make sure you");
158		log_error ("are not running HP JetAdmin software, which");
159		log_fatal ("includes a bootp server.");
160	}
161
162#if defined (HAVE_SO_BINDTODEVICE)
163	/* Bind this socket to this interface. */
164	if (info -> ifp &&
165	    setsockopt (sock, SOL_SOCKET, SO_BINDTODEVICE,
166			(char *)(info -> ifp), sizeof *(info -> ifp)) < 0) {
167		log_fatal ("setsockopt: SO_BINDTODEVICE: %m");
168	}
169#endif
170
171	return sock;
172}
173#endif /* USE_SOCKET_SEND || USE_SOCKET_RECEIVE || USE_SOCKET_FALLBACK */
174
175#if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
176void if_register_send (info)
177	struct interface_info *info;
178{
179#ifndef USE_SOCKET_RECEIVE
180	info -> wfdesc = if_register_socket (info);
181#if defined (USE_SOCKET_FALLBACK)
182	/* Fallback only registers for send, but may need to receive as
183	   well. */
184	info -> rfdesc = info -> wfdesc;
185#endif
186#else
187	info -> wfdesc = info -> rfdesc;
188#endif
189	if (!quiet_interface_discovery)
190		log_info ("Sending on   Socket/%s%s%s",
191		      info -> name,
192		      (info -> shared_network ? "/" : ""),
193		      (info -> shared_network ?
194		       info -> shared_network -> name : ""));
195}
196
197#if defined (USE_SOCKET_SEND)
198void if_deregister_send (info)
199	struct interface_info *info;
200{
201#ifndef USE_SOCKET_RECEIVE
202	close (info -> wfdesc);
203#endif
204	info -> wfdesc = -1;
205
206	if (!quiet_interface_discovery)
207		log_info ("Disabling output on Socket/%s%s%s",
208		      info -> name,
209		      (info -> shared_network ? "/" : ""),
210		      (info -> shared_network ?
211		       info -> shared_network -> name : ""));
212}
213#endif /* USE_SOCKET_SEND */
214#endif /* USE_SOCKET_SEND || USE_SOCKET_FALLBACK */
215
216#ifdef USE_SOCKET_RECEIVE
217void if_register_receive (info)
218	struct interface_info *info;
219{
220	/* If we're using the socket API for sending and receiving,
221	   we don't need to register this interface twice. */
222	info -> rfdesc = if_register_socket (info);
223	if (!quiet_interface_discovery)
224		log_info ("Listening on Socket/%s%s%s",
225		      info -> name,
226		      (info -> shared_network ? "/" : ""),
227		      (info -> shared_network ?
228		       info -> shared_network -> name : ""));
229}
230
231void if_deregister_receive (info)
232	struct interface_info *info;
233{
234	close (info -> rfdesc);
235	info -> rfdesc = -1;
236
237	if (!quiet_interface_discovery)
238		log_info ("Disabling input on Socket/%s%s%s",
239		      info -> name,
240		      (info -> shared_network ? "/" : ""),
241		      (info -> shared_network ?
242		       info -> shared_network -> name : ""));
243}
244#endif /* USE_SOCKET_RECEIVE */
245
246#if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)
247ssize_t send_packet (interface, packet, raw, len, from, to, hto)
248	struct interface_info *interface;
249	struct packet *packet;
250	struct dhcp_packet *raw;
251	size_t len;
252	struct in_addr from;
253	struct sockaddr_in *to;
254	struct hardware *hto;
255{
256	int result;
257#ifdef IGNORE_HOSTUNREACH
258	int retry = 0;
259	do {
260#endif
261		result = sendto (interface -> wfdesc, (char *)raw, len, 0,
262				 (struct sockaddr *)to, sizeof *to);
263#ifdef IGNORE_HOSTUNREACH
264	} while (to -> sin_addr.s_addr == htonl (INADDR_BROADCAST) &&
265		 result < 0 &&
266		 (errno == EHOSTUNREACH ||
267		  errno == ECONNREFUSED) &&
268		 retry++ < 10);
269#endif
270	if (result < 0) {
271		log_error ("send_packet: %m");
272		if (errno == ENETUNREACH)
273			log_error ("send_packet: please consult README file%s",
274				   " regarding broadcast address.");
275	}
276	return result;
277}
278#endif /* USE_SOCKET_SEND || USE_SOCKET_FALLBACK */
279
280#ifdef USE_SOCKET_RECEIVE
281ssize_t receive_packet (interface, buf, len, from, hfrom)
282	struct interface_info *interface;
283	unsigned char *buf;
284	size_t len;
285	struct sockaddr_in *from;
286	struct hardware *hfrom;
287{
288	SOCKLEN_T flen = sizeof *from;
289	int result;
290
291#ifdef IGNORE_HOSTUNREACH
292	int retry = 0;
293	do {
294#endif
295		result = recvfrom (interface -> rfdesc, (char *)buf, len, 0,
296				   (struct sockaddr *)from, &flen);
297#ifdef IGNORE_HOSTUNREACH
298	} while (result < 0 &&
299		 (errno == EHOSTUNREACH ||
300		  errno == ECONNREFUSED) &&
301		 retry++ < 10);
302#endif
303	return result;
304}
305#endif /* USE_SOCKET_RECEIVE */
306
307#if defined (USE_SOCKET_FALLBACK)
308/* This just reads in a packet and silently discards it. */
309
310isc_result_t fallback_discard (object)
311	omapi_object_t *object;
312{
313	char buf [1540];
314	struct sockaddr_in from;
315	SOCKLEN_T flen = sizeof from;
316	int status;
317	struct interface_info *interface;
318
319	if (object -> type != dhcp_type_interface)
320		return ISC_R_INVALIDARG;
321	interface = (struct interface_info *)object;
322
323	status = recvfrom (interface -> wfdesc, buf, sizeof buf, 0,
324			   (struct sockaddr *)&from, &flen);
325#if defined (DEBUG)
326	/* Only report fallback discard errors if we're debugging. */
327	if (status < 0) {
328		log_error ("fallback_discard: %m");
329		return ISC_R_UNEXPECTED;
330	}
331#endif
332	return ISC_R_SUCCESS;
333}
334#endif /* USE_SOCKET_FALLBACK */
335
336#if defined (USE_SOCKET_SEND)
337int can_unicast_without_arp (ip)
338	struct interface_info *ip;
339{
340	return 0;
341}
342
343int can_receive_unicast_unconfigured (ip)
344	struct interface_info *ip;
345{
346#if defined (SOCKET_CAN_RECEIVE_UNICAST_UNCONFIGURED)
347	return 1;
348#else
349	return 0;
350#endif
351}
352
353int supports_multiple_interfaces (ip)
354	struct interface_info *ip;
355{
356#if defined (SO_BINDTODEVICE)
357	return 1;
358#else
359	return 0;
360#endif
361}
362
363/* If we have SO_BINDTODEVICE, set up a fallback interface; otherwise,
364   do not. */
365
366void maybe_setup_fallback ()
367{
368#if defined (USE_SOCKET_FALLBACK)
369	isc_result_t status;
370	struct interface_info *fbi = (struct interface_info *)0;
371	if (setup_fallback (&fbi, MDL)) {
372		fbi -> wfdesc = if_register_socket (fbi);
373		fbi -> rfdesc = fbi -> wfdesc;
374		log_info ("Sending on   Socket/%s%s%s",
375		      fbi -> name,
376		      (fbi -> shared_network ? "/" : ""),
377		      (fbi -> shared_network ?
378		       fbi -> shared_network -> name : ""));
379
380		status = omapi_register_io_object ((omapi_object_t *)fbi,
381						   if_readsocket, 0,
382						   fallback_discard, 0, 0);
383		if (status != ISC_R_SUCCESS)
384			log_fatal ("Can't register I/O handle for %s: %s",
385				   fbi -> name, isc_result_totext (status));
386		interface_dereference (&fbi, MDL);
387	}
388#endif
389}
390#endif /* USE_SOCKET_SEND */
391