xref: /freebsd/lib/libc/net/getnetbydns.c (revision 6990ffd8a95caaba6858ad44ff1b3157d1efba8f)
1 /*-
2  * Copyright (c) 1985, 1988, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  * -
33  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
34  *
35  * Permission to use, copy, modify, and distribute this software for any
36  * purpose with or without fee is hereby granted, provided that the above
37  * copyright notice and this permission notice appear in all copies, and that
38  * the name of Digital Equipment Corporation not be used in advertising or
39  * publicity pertaining to distribution of the document or software without
40  * specific, written prior permission.
41  *
42  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
43  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
44  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
45  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
46  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
47  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
48  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
49  * SOFTWARE.
50  * -
51  * --Copyright--
52  */
53 /* Portions Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
54  *	Dep. Matematica Universidade de Coimbra, Portugal, Europe
55  *
56  * Permission to use, copy, modify, and distribute this software for any
57  * purpose with or without fee is hereby granted, provided that the above
58  * copyright notice and this permission notice appear in all copies.
59  */
60 
61 #if defined(LIBC_SCCS) && !defined(lint)
62 static char sccsid[] = "@(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93";
63 static char rcsid[] = "$FreeBSD$";
64 #endif /* LIBC_SCCS and not lint */
65 
66 #include <sys/param.h>
67 #include <sys/socket.h>
68 #include <netinet/in.h>
69 #include <arpa/inet.h>
70 #include <arpa/nameser.h>
71 
72 #include <stdio.h>
73 #include <netdb.h>
74 #include <resolv.h>
75 #include <ctype.h>
76 #include <string.h>
77 #include <unistd.h>
78 #include <syslog.h>
79 #include <stdarg.h>
80 #include <nsswitch.h>
81 
82 #include "res_config.h"
83 
84 extern int h_errno;
85 
86 #define BYADDR 0
87 #define BYNAME 1
88 #define	MAXALIASES	35
89 
90 #if PACKETSZ > 1024
91 #define	MAXPACKET	PACKETSZ
92 #else
93 #define	MAXPACKET	1024
94 #endif
95 
96 typedef union {
97 	HEADER	hdr;
98 	u_char	buf[MAXPACKET];
99 } querybuf;
100 
101 typedef union {
102 	long	al;
103 	char	ac;
104 } align;
105 
106 static struct netent *
107 getnetanswer(answer, anslen, net_i)
108 	querybuf *answer;
109 	int anslen;
110 	int net_i;
111 {
112 
113 	register HEADER *hp;
114 	register u_char *cp;
115 	register int n;
116 	u_char *eom;
117 	int type, class, buflen, ancount, qdcount, haveanswer, i, nchar;
118 	char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN];
119 	char *in, *st, *pauxt, *bp, **ap;
120 	char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;
121 static	struct netent net_entry;
122 static	char *net_aliases[MAXALIASES], netbuf[PACKETSZ];
123 
124 	/*
125 	 * find first satisfactory answer
126 	 *
127 	 *      answer --> +------------+  ( MESSAGE )
128 	 *		   |   Header   |
129 	 *		   +------------+
130 	 *		   |  Question  | the question for the name server
131 	 *		   +------------+
132 	 *		   |   Answer   | RRs answering the question
133 	 *		   +------------+
134 	 *		   | Authority  | RRs pointing toward an authority
135 	 *		   | Additional | RRs holding additional information
136 	 *		   +------------+
137 	 */
138 	eom = answer->buf + anslen;
139 	hp = &answer->hdr;
140 	ancount = ntohs(hp->ancount); /* #/records in the answer section */
141 	qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
142 	bp = netbuf;
143 	buflen = sizeof(netbuf);
144 	cp = answer->buf + HFIXEDSZ;
145 	if (!qdcount) {
146 		if (hp->aa)
147 			h_errno = HOST_NOT_FOUND;
148 		else
149 			h_errno = TRY_AGAIN;
150 		return (NULL);
151 	}
152 	while (qdcount-- > 0)
153 		cp += __dn_skipname(cp, eom) + QFIXEDSZ;
154 	ap = net_aliases;
155 	*ap = NULL;
156 	net_entry.n_aliases = net_aliases;
157 	haveanswer = 0;
158 	while (--ancount >= 0 && cp < eom) {
159 		n = dn_expand(answer->buf, eom, cp, bp, buflen);
160 		if ((n < 0) || !res_dnok(bp))
161 			break;
162 		cp += n;
163 		ans[0] = '\0';
164 		(void)strncpy(&ans[0], bp, sizeof(ans) - 1);
165 		ans[sizeof(ans) - 1] = '\0';
166 		GETSHORT(type, cp);
167 		GETSHORT(class, cp);
168 		cp += INT32SZ;		/* TTL */
169 		GETSHORT(n, cp);
170 		if (class == C_IN && type == T_PTR) {
171 			n = dn_expand(answer->buf, eom, cp, bp, buflen);
172 			if ((n < 0) || !res_hnok(bp)) {
173 				cp += n;
174 				return (NULL);
175 			}
176 			cp += n;
177 			*ap++ = bp;
178 			bp += strlen(bp) + 1;
179 			net_entry.n_addrtype =
180 				(class == C_IN) ? AF_INET : AF_UNSPEC;
181 			haveanswer++;
182 		}
183 	}
184 	if (haveanswer) {
185 		*ap = NULL;
186 		switch (net_i) {
187 		case BYADDR:
188 			net_entry.n_name = *net_entry.n_aliases;
189 			net_entry.n_net = 0L;
190 			break;
191 		case BYNAME:
192 			in = *net_entry.n_aliases;
193 			net_entry.n_name = &ans[0];
194 			aux2[0] = '\0';
195 			for (i = 0; i < 4; i++) {
196 				for (st = in, nchar = 0;
197 				     *st != '.';
198 				     st++, nchar++)
199 					;
200 				if (nchar != 1 || *in != '0' || flag) {
201 					flag = 1;
202 					(void)strncpy(paux1,
203 						      (i==0) ? in : in-1,
204 						      (i==0) ?nchar : nchar+1);
205 					paux1[(i==0) ? nchar : nchar+1] = '\0';
206 					pauxt = paux2;
207 					paux2 = strcat(paux1, paux2);
208 					paux1 = pauxt;
209 				}
210 				in = ++st;
211 			}
212 			net_entry.n_net = inet_network(paux2);
213 			break;
214 		}
215 		net_entry.n_aliases++;
216 		return (&net_entry);
217 	}
218 	h_errno = TRY_AGAIN;
219 	return (NULL);
220 }
221 
222 int
223 _dns_getnetbyaddr(void *rval, void *cb_data, va_list ap)
224 {
225 	unsigned long net;
226 	int net_type;
227 	unsigned int netbr[4];
228 	int nn, anslen;
229 	querybuf buf;
230 	char qbuf[MAXDNAME];
231 	unsigned long net2;
232 	struct netent *net_entry;
233 
234 	net = va_arg(ap, unsigned long);
235 	net_type = va_arg(ap, int);
236 
237 	*(struct netent **)rval = NULL;
238 
239 	if (net_type != AF_INET)
240 		return NS_UNAVAIL;
241 
242 	for (nn = 4, net2 = net; net2; net2 >>= 8)
243 		netbr[--nn] = net2 & 0xff;
244 	switch (nn) {
245 	case 3: 	/* Class A */
246 		sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);
247 		break;
248 	case 2: 	/* Class B */
249 		sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);
250 		break;
251 	case 1: 	/* Class C */
252 		sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
253 		    netbr[1]);
254 		break;
255 	case 0: 	/* Class D - E */
256 		sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
257 		    netbr[1], netbr[0]);
258 		break;
259 	}
260 	anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
261 	if (anslen < 0) {
262 #ifdef DEBUG
263 		if (_res.options & RES_DEBUG)
264 			printf("res_query failed\n");
265 #endif
266 		return NS_UNAVAIL;
267 	}
268 	net_entry = getnetanswer(&buf, anslen, BYADDR);
269 	if (net_entry) {
270 		unsigned u_net = net;	/* maybe net should be unsigned ? */
271 
272 		/* Strip trailing zeros */
273 		while ((u_net & 0xff) == 0 && u_net != 0)
274 			u_net >>= 8;
275 		net_entry->n_net = u_net;
276 		*(struct netent **)rval = net_entry;
277 		return NS_SUCCESS;
278 	}
279 	return NS_NOTFOUND;
280 }
281 
282 int
283 _dns_getnetbyname(void *rval, void *cb_data, va_list ap)
284 {
285 	const char *net;
286 	int anslen;
287 	querybuf buf;
288 	char qbuf[MAXDNAME];
289 
290 	net = va_arg(ap, const char *);
291 
292 	*(struct netent**)rval = NULL;
293 
294 	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
295 		h_errno = NETDB_INTERNAL;
296 		return NS_UNAVAIL;
297 	}
298 	strncpy(qbuf, net, sizeof(qbuf) - 1);
299 	qbuf[sizeof(qbuf) - 1] = '\0';
300 	anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
301 	if (anslen < 0) {
302 #ifdef DEBUG
303 		if (_res.options & RES_DEBUG)
304 			printf("res_query failed\n");
305 #endif
306 		return NS_UNAVAIL;
307 	}
308 	*(struct netent**)rval = getnetanswer(&buf, anslen, BYNAME);
309 	return (*(struct netent**)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
310 }
311 
312 void
313 _setnetdnsent(stayopen)
314 	int stayopen;
315 {
316 	if (stayopen)
317 		_res.options |= RES_STAYOPEN | RES_USEVC;
318 }
319 
320 void
321 _endnetdnsent()
322 {
323 	_res.options &= ~(RES_STAYOPEN | RES_USEVC);
324 	res_close();
325 }
326