1 /*
2 * Copyright (c) 1985, 1988 Regents of the University of California.
3 * 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
34 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)gethostnamadr.c 6.45 (Berkeley) 2/24/91";
36 #endif /* LIBC_SCCS and not lint */
37
38 #include <sys/param.h>
39 #include <sys/socket.h>
40 #include <netinet/in.h>
41 #include <arpa/inet.h>
42 #include <arpa/nameser.h>
43 #include <netdb.h>
44 #include <resolv.h>
45 #include <stdio.h>
46 #include <ctype.h>
47 #include <errno.h>
48 #include <string.h>
49
50 #define MAXALIASES 35
51 #define MAXADDRS 35
52
53 static char *h_addr_ptrs[MAXADDRS + 1];
54
55 static struct hostent host;
56 static char *host_aliases[MAXALIASES];
57 static char hostbuf[BUFSIZ+1];
58 static struct in_addr host_addr;
59 static FILE *hostf = NULL;
60 static char hostaddr[MAXADDRS];
61 static char *host_addrs[2];
62 static int stayopen = 0;
63 char *strpbrk();
64
65 #if PACKETSZ > 1024
66 #define MAXPACKET PACKETSZ
67 #else
68 #define MAXPACKET 1024
69 #endif
70
71 typedef union {
72 HEADER hdr;
73 u_char buf[MAXPACKET];
74 } querybuf;
75
76 typedef union {
77 long al;
78 char ac;
79 } align;
80
81 int h_errno;
82
83 static struct hostent *
getanswer(answer,anslen,iquery)84 getanswer(answer, anslen, iquery)
85 querybuf *answer;
86 int anslen;
87 int iquery;
88 {
89 register HEADER *hp;
90 register u_char *cp;
91 register int n;
92 u_char *eom;
93 char *bp, **ap;
94 int type, class, buflen, ancount, qdcount;
95 int haveanswer, getclass = C_ANY;
96 char **hap;
97
98 eom = answer->buf + anslen;
99 /*
100 * find first satisfactory answer
101 */
102 hp = &answer->hdr;
103 ancount = ntohs(hp->ancount);
104 qdcount = ntohs(hp->qdcount);
105 bp = hostbuf;
106 buflen = sizeof(hostbuf);
107 cp = answer->buf + sizeof(HEADER);
108 if (qdcount) {
109 if (iquery) {
110 if ((n = dn_expand((u_char *)answer->buf,
111 (u_char *)eom, (u_char *)cp, (u_char *)bp,
112 buflen)) < 0) {
113 h_errno = NO_RECOVERY;
114 return ((struct hostent *) NULL);
115 }
116 cp += n + QFIXEDSZ;
117 host.h_name = bp;
118 n = strlen(bp) + 1;
119 bp += n;
120 buflen -= n;
121 } else
122 cp += __dn_skipname(cp, eom) + QFIXEDSZ;
123 while (--qdcount > 0)
124 cp += __dn_skipname(cp, eom) + QFIXEDSZ;
125 } else if (iquery) {
126 if (hp->aa)
127 h_errno = HOST_NOT_FOUND;
128 else
129 h_errno = TRY_AGAIN;
130 return ((struct hostent *) NULL);
131 }
132 ap = host_aliases;
133 *ap = NULL;
134 host.h_aliases = host_aliases;
135 hap = h_addr_ptrs;
136 *hap = NULL;
137 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
138 host.h_addr_list = h_addr_ptrs;
139 #endif
140 haveanswer = 0;
141 while (--ancount >= 0 && cp < eom) {
142 if ((n = dn_expand((u_char *)answer->buf, (u_char *)eom,
143 (u_char *)cp, (u_char *)bp, buflen)) < 0)
144 break;
145 cp += n;
146 type = _getshort(cp);
147 cp += sizeof(u_short);
148 class = _getshort(cp);
149 cp += sizeof(u_short) + sizeof(u_long);
150 n = _getshort(cp);
151 cp += sizeof(u_short);
152 if (type == T_CNAME) {
153 cp += n;
154 if (ap >= &host_aliases[MAXALIASES-1])
155 continue;
156 *ap++ = bp;
157 n = strlen(bp) + 1;
158 bp += n;
159 buflen -= n;
160 continue;
161 }
162 if (iquery && type == T_PTR) {
163 if ((n = dn_expand((u_char *)answer->buf,
164 (u_char *)eom, (u_char *)cp, (u_char *)bp,
165 buflen)) < 0) {
166 cp += n;
167 continue;
168 }
169 cp += n;
170 host.h_name = bp;
171 return(&host);
172 }
173 if (iquery || type != T_A) {
174 #ifdef DEBUG
175 if (_res.options & RES_DEBUG)
176 printf("unexpected answer type %d, size %d\n",
177 type, n);
178 #endif
179 cp += n;
180 continue;
181 }
182 if (haveanswer) {
183 if (n != host.h_length) {
184 cp += n;
185 continue;
186 }
187 if (class != getclass) {
188 cp += n;
189 continue;
190 }
191 } else {
192 host.h_length = n;
193 getclass = class;
194 host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC;
195 if (!iquery) {
196 host.h_name = bp;
197 bp += strlen(bp) + 1;
198 }
199 }
200
201 bp += sizeof(align) - ((u_long)bp % sizeof(align));
202
203 if (bp + n >= &hostbuf[sizeof(hostbuf)]) {
204 #ifdef DEBUG
205 if (_res.options & RES_DEBUG)
206 printf("size (%d) too big\n", n);
207 #endif
208 break;
209 }
210 bcopy(cp, *hap++ = bp, n);
211 bp +=n;
212 cp += n;
213 haveanswer++;
214 }
215 if (haveanswer) {
216 *ap = NULL;
217 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
218 *hap = NULL;
219 #else
220 host.h_addr = h_addr_ptrs[0];
221 #endif
222 return (&host);
223 } else {
224 h_errno = TRY_AGAIN;
225 return ((struct hostent *) NULL);
226 }
227 }
228
229 struct hostent *
gethostbyname(name)230 gethostbyname(name)
231 char *name;
232 {
233 querybuf buf;
234 register char *cp;
235 int n;
236 extern struct hostent *_gethtbyname();
237
238 /*
239 * disallow names consisting only of digits/dots, unless
240 * they end in a dot.
241 */
242 if (isdigit(name[0]))
243 for (cp = name;; ++cp) {
244 if (!*cp) {
245 if (*--cp == '.')
246 break;
247 /*
248 * All-numeric, no dot at the end.
249 * Fake up a hostent as if we'd actually
250 * done a lookup. What if someone types
251 * 255.255.255.255? The test below will
252 * succeed spuriously... ???
253 */
254 if ((host_addr.s_addr = inet_addr(name)) == -1) {
255 h_errno = HOST_NOT_FOUND;
256 return((struct hostent *) NULL);
257 }
258 host.h_name = name;
259 host.h_aliases = host_aliases;
260 host_aliases[0] = NULL;
261 host.h_addrtype = AF_INET;
262 host.h_length = sizeof(u_long);
263 h_addr_ptrs[0] = (char *)&host_addr;
264 h_addr_ptrs[1] = (char *)0;
265 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
266 host.h_addr_list = h_addr_ptrs;
267 #else
268 host.h_addr = h_addr_ptrs[0];
269 #endif
270 return (&host);
271 }
272 if (!isdigit(*cp) && *cp != '.')
273 break;
274 }
275
276 if ((n = res_search(name, C_IN, T_A, buf.buf, sizeof(buf))) < 0) {
277 #ifdef DEBUG
278 if (_res.options & RES_DEBUG)
279 printf("res_search failed\n");
280 #endif
281 if (errno == ECONNREFUSED)
282 return (_gethtbyname(name));
283 else
284 return ((struct hostent *) NULL);
285 }
286 return (getanswer(&buf, n, 0));
287 }
288
289 struct hostent *
gethostbyaddr(addr,len,type)290 gethostbyaddr(addr, len, type)
291 const char *addr;
292 int len, type;
293 {
294 int n;
295 querybuf buf;
296 register struct hostent *hp;
297 char qbuf[MAXDNAME];
298 extern struct hostent *_gethtbyaddr();
299
300 if (type != AF_INET)
301 return ((struct hostent *) NULL);
302 (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
303 ((unsigned)addr[3] & 0xff),
304 ((unsigned)addr[2] & 0xff),
305 ((unsigned)addr[1] & 0xff),
306 ((unsigned)addr[0] & 0xff));
307 n = res_query(qbuf, C_IN, T_PTR, (char *)&buf, sizeof(buf));
308 if (n < 0) {
309 #ifdef DEBUG
310 if (_res.options & RES_DEBUG)
311 printf("res_query failed\n");
312 #endif
313 if (errno == ECONNREFUSED)
314 return (_gethtbyaddr(addr, len, type));
315 return ((struct hostent *) NULL);
316 }
317 hp = getanswer(&buf, n, 1);
318 if (hp == NULL)
319 return ((struct hostent *) NULL);
320 hp->h_addrtype = type;
321 hp->h_length = len;
322 h_addr_ptrs[0] = (char *)&host_addr;
323 h_addr_ptrs[1] = (char *)0;
324 host_addr = *(struct in_addr *)addr;
325 #if BSD < 43 && !defined(h_addr) /* new-style hostent structure */
326 hp->h_addr = h_addr_ptrs[0];
327 #endif
328 return(hp);
329 }
330
_sethtent(f)331 _sethtent(f)
332 int f;
333 {
334 if (hostf == NULL)
335 hostf = fopen(_PATH_HOSTS, "r" );
336 else
337 rewind(hostf);
338 stayopen |= f;
339 }
340
_endhtent()341 _endhtent()
342 {
343 if (hostf && !stayopen) {
344 (void) fclose(hostf);
345 hostf = NULL;
346 }
347 }
348
349 struct hostent *
_gethtent()350 _gethtent()
351 {
352 char *p;
353 register char *cp, **q;
354
355 if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
356 return (NULL);
357 again:
358 if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
359 return (NULL);
360 if (*p == '#')
361 goto again;
362 cp = strpbrk(p, "#\n");
363 if (cp == NULL)
364 goto again;
365 *cp = '\0';
366 cp = strpbrk(p, " \t");
367 if (cp == NULL)
368 goto again;
369 *cp++ = '\0';
370 /* THIS STUFF IS INTERNET SPECIFIC */
371 #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
372 host.h_addr_list = host_addrs;
373 #endif
374 host.h_addr = hostaddr;
375 *((u_long *)host.h_addr) = inet_addr(p);
376 host.h_length = sizeof (u_long);
377 host.h_addrtype = AF_INET;
378 while (*cp == ' ' || *cp == '\t')
379 cp++;
380 host.h_name = cp;
381 q = host.h_aliases = host_aliases;
382 cp = strpbrk(cp, " \t");
383 if (cp != NULL)
384 *cp++ = '\0';
385 while (cp && *cp) {
386 if (*cp == ' ' || *cp == '\t') {
387 cp++;
388 continue;
389 }
390 if (q < &host_aliases[MAXALIASES - 1])
391 *q++ = cp;
392 cp = strpbrk(cp, " \t");
393 if (cp != NULL)
394 *cp++ = '\0';
395 }
396 *q = NULL;
397 return (&host);
398 }
399
400 struct hostent *
_gethtbyname(name)401 _gethtbyname(name)
402 char *name;
403 {
404 register struct hostent *p;
405 register char **cp;
406
407 _sethtent(0);
408 while (p = _gethtent()) {
409 if (strcasecmp(p->h_name, name) == 0)
410 break;
411 for (cp = p->h_aliases; *cp != 0; cp++)
412 if (strcasecmp(*cp, name) == 0)
413 goto found;
414 }
415 found:
416 _endhtent();
417 return (p);
418 }
419
420 struct hostent *
_gethtbyaddr(addr,len,type)421 _gethtbyaddr(addr, len, type)
422 const char *addr;
423 int len, type;
424 {
425 register struct hostent *p;
426
427 _sethtent(0);
428 while (p = _gethtent())
429 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
430 break;
431 _endhtent();
432 return (p);
433 }
434