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1.1 root 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 are permitted
6: * provided that: (1) source distributions retain this entire copyright
7: * notice and comment, and (2) distributions including binaries display
8: * the following acknowledgement: ``This product includes software
9: * developed by the University of California, Berkeley and its contributors''
10: * in the documentation or other materials provided with the distribution
11: * and in all advertising materials mentioning features or use of this
12: * software. Neither the name of the University nor the names of its
13: * contributors may be used to endorse or promote products derived
14: * from this software without specific prior written permission.
15: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
17: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
18: */
19:
20: #if defined(LIBC_SCCS) && !defined(lint)
21: static char sccsid[] = "@(#)gethostnamadr.c 6.41 (Berkeley) 6/1/90";
22: #endif /* LIBC_SCCS and not lint */
23:
24: #include <sys/param.h>
25: #include <sys/socket.h>
26: #include <netinet/in.h>
27: #include <ctype.h>
28: #include <netdb.h>
29: #include <stdio.h>
30: #include <errno.h>
31: #include <arpa/inet.h>
32: #include <arpa/nameser.h>
33: #include <resolv.h>
34:
35: #define MAXALIASES 35
36: #define MAXADDRS 35
37:
38: static char *h_addr_ptrs[MAXADDRS + 1];
39:
40: static struct hostent host;
41: static char *host_aliases[MAXALIASES];
42: static char hostbuf[BUFSIZ+1];
43: static struct in_addr host_addr;
44: static FILE *hostf = NULL;
45: static char hostaddr[MAXADDRS];
46: static char *host_addrs[2];
47: static int stayopen = 0;
48: char *strpbrk();
49:
50: #if PACKETSZ > 1024
51: #define MAXPACKET PACKETSZ
52: #else
53: #define MAXPACKET 1024
54: #endif
55:
56: typedef union {
57: HEADER hdr;
58: u_char buf[MAXPACKET];
59: } querybuf;
60:
61: typedef union {
62: long al;
63: char ac;
64: } align;
65:
66:
67: int h_errno;
68: extern errno;
69:
70: static struct hostent *
71: getanswer(answer, anslen, iquery)
72: querybuf *answer;
73: int anslen;
74: int iquery;
75: {
76: register HEADER *hp;
77: register u_char *cp;
78: register int n;
79: u_char *eom;
80: char *bp, **ap;
81: int type, class, buflen, ancount, qdcount;
82: int haveanswer, getclass = C_ANY;
83: char **hap;
84:
85: eom = answer->buf + anslen;
86: /*
87: * find first satisfactory answer
88: */
89: hp = &answer->hdr;
90: ancount = ntohs(hp->ancount);
91: qdcount = ntohs(hp->qdcount);
92: bp = hostbuf;
93: buflen = sizeof(hostbuf);
94: cp = answer->buf + sizeof(HEADER);
95: if (qdcount) {
96: if (iquery) {
97: if ((n = dn_expand((char *)answer->buf, eom,
98: cp, bp, buflen)) < 0) {
99: h_errno = NO_RECOVERY;
100: return ((struct hostent *) NULL);
101: }
102: cp += n + QFIXEDSZ;
103: host.h_name = bp;
104: n = strlen(bp) + 1;
105: bp += n;
106: buflen -= n;
107: } else
108: cp += dn_skipname(cp, eom) + QFIXEDSZ;
109: while (--qdcount > 0)
110: cp += dn_skipname(cp, eom) + QFIXEDSZ;
111: } else if (iquery) {
112: if (hp->aa)
113: h_errno = HOST_NOT_FOUND;
114: else
115: h_errno = TRY_AGAIN;
116: return ((struct hostent *) NULL);
117: }
118: ap = host_aliases;
119: *ap = NULL;
120: host.h_aliases = host_aliases;
121: hap = h_addr_ptrs;
122: *hap = NULL;
123: #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
124: host.h_addr_list = h_addr_ptrs;
125: #endif
126: haveanswer = 0;
127: while (--ancount >= 0 && cp < eom) {
128: if ((n = dn_expand((char *)answer->buf, eom, cp, bp, buflen)) < 0)
129: break;
130: cp += n;
131: type = _getshort(cp);
132: cp += sizeof(u_short);
133: class = _getshort(cp);
134: cp += sizeof(u_short) + sizeof(u_long);
135: n = _getshort(cp);
136: cp += sizeof(u_short);
137: if (type == T_CNAME) {
138: cp += n;
139: if (ap >= &host_aliases[MAXALIASES-1])
140: continue;
141: *ap++ = bp;
142: n = strlen(bp) + 1;
143: bp += n;
144: buflen -= n;
145: continue;
146: }
147: if (iquery && type == T_PTR) {
148: if ((n = dn_expand((char *)answer->buf, eom,
149: cp, bp, buflen)) < 0) {
150: cp += n;
151: continue;
152: }
153: cp += n;
154: host.h_name = bp;
155: return(&host);
156: }
157: if (iquery || type != T_A) {
158: #ifdef DEBUG
159: if (_res.options & RES_DEBUG)
160: printf("unexpected answer type %d, size %d\n",
161: type, n);
162: #endif
163: cp += n;
164: continue;
165: }
166: if (haveanswer) {
167: if (n != host.h_length) {
168: cp += n;
169: continue;
170: }
171: if (class != getclass) {
172: cp += n;
173: continue;
174: }
175: } else {
176: host.h_length = n;
177: getclass = class;
178: host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC;
179: if (!iquery) {
180: host.h_name = bp;
181: bp += strlen(bp) + 1;
182: }
183: }
184:
185: bp += sizeof(align) - ((u_long)bp % sizeof(align));
186:
187: if (bp + n >= &hostbuf[sizeof(hostbuf)]) {
188: #ifdef DEBUG
189: if (_res.options & RES_DEBUG)
190: printf("size (%d) too big\n", n);
191: #endif
192: break;
193: }
194: bcopy(cp, *hap++ = bp, n);
195: bp +=n;
196: cp += n;
197: haveanswer++;
198: }
199: if (haveanswer) {
200: *ap = NULL;
201: #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
202: *hap = NULL;
203: #else
204: host.h_addr = h_addr_ptrs[0];
205: #endif
206: return (&host);
207: } else {
208: h_errno = TRY_AGAIN;
209: return ((struct hostent *) NULL);
210: }
211: }
212:
213: struct hostent *
214: gethostbyname(name)
215: char *name;
216: {
217: querybuf buf;
218: register char *cp;
219: int n;
220: extern struct hostent *_gethtbyname();
221:
222: /*
223: * disallow names consisting only of digits/dots, unless
224: * they end in a dot.
225: */
226: if (isdigit(name[0]))
227: for (cp = name;; ++cp) {
228: if (!*cp) {
229: if (*--cp == '.')
230: break;
231: /*
232: * All-numeric, no dot at the end.
233: * Fake up a hostent as if we'd actually
234: * done a lookup. What if someone types
235: * 255.255.255.255? The test below will
236: * succeed spuriously... ???
237: */
238: if ((host_addr.s_addr = inet_addr(name)) == -1) {
239: h_errno = HOST_NOT_FOUND;
240: return((struct hostent *) NULL);
241: }
242: host.h_name = name;
243: host.h_aliases = host_aliases;
244: host_aliases[0] = NULL;
245: host.h_addrtype = AF_INET;
246: host.h_length = sizeof(u_long);
247: h_addr_ptrs[0] = (char *)&host_addr;
248: h_addr_ptrs[1] = (char *)0;
249: #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
250: host.h_addr_list = h_addr_ptrs;
251: #else
252: host.h_addr = h_addr_ptrs[0];
253: #endif
254: return (&host);
255: }
256: if (!isdigit(*cp) && *cp != '.')
257: break;
258: }
259:
260: if ((n = res_search(name, C_IN, T_A, buf.buf, sizeof(buf))) < 0) {
261: #ifdef DEBUG
262: if (_res.options & RES_DEBUG)
263: printf("res_search failed\n");
264: #endif
265: if (errno == ECONNREFUSED)
266: return (_gethtbyname(name));
267: else
268: return ((struct hostent *) NULL);
269: }
270: return (getanswer(&buf, n, 0));
271: }
272:
273: struct hostent *
274: gethostbyaddr(addr, len, type)
275: char *addr;
276: int len, type;
277: {
278: int n;
279: querybuf buf;
280: register struct hostent *hp;
281: char qbuf[MAXDNAME];
282: extern struct hostent *_gethtbyaddr();
283:
284: if (type != AF_INET)
285: return ((struct hostent *) NULL);
286: (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
287: ((unsigned)addr[3] & 0xff),
288: ((unsigned)addr[2] & 0xff),
289: ((unsigned)addr[1] & 0xff),
290: ((unsigned)addr[0] & 0xff));
291: n = res_query(qbuf, C_IN, T_PTR, (char *)&buf, sizeof(buf));
292: if (n < 0) {
293: #ifdef DEBUG
294: if (_res.options & RES_DEBUG)
295: printf("res_query failed\n");
296: #endif
297: if (errno == ECONNREFUSED)
298: return (_gethtbyaddr(addr, len, type));
299: return ((struct hostent *) NULL);
300: }
301: hp = getanswer(&buf, n, 1);
302: if (hp == NULL)
303: return ((struct hostent *) NULL);
304: hp->h_addrtype = type;
305: hp->h_length = len;
306: h_addr_ptrs[0] = (char *)&host_addr;
307: h_addr_ptrs[1] = (char *)0;
308: host_addr = *(struct in_addr *)addr;
309: #if BSD < 43 && !defined(h_addr) /* new-style hostent structure */
310: hp->h_addr = h_addr_ptrs[0];
311: #endif
312: return(hp);
313: }
314:
315: _sethtent(f)
316: int f;
317: {
318: if (hostf == NULL)
319: hostf = fopen(_PATH_HOSTS, "r" );
320: else
321: rewind(hostf);
322: stayopen |= f;
323: }
324:
325: _endhtent()
326: {
327: if (hostf && !stayopen) {
328: (void) fclose(hostf);
329: hostf = NULL;
330: }
331: }
332:
333: struct hostent *
334: _gethtent()
335: {
336: char *p;
337: register char *cp, **q;
338:
339: if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
340: return (NULL);
341: again:
342: if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
343: return (NULL);
344: if (*p == '#')
345: goto again;
346: cp = strpbrk(p, "#\n");
347: if (cp == NULL)
348: goto again;
349: *cp = '\0';
350: cp = strpbrk(p, " \t");
351: if (cp == NULL)
352: goto again;
353: *cp++ = '\0';
354: /* THIS STUFF IS INTERNET SPECIFIC */
355: #if BSD >= 43 || defined(h_addr) /* new-style hostent structure */
356: host.h_addr_list = host_addrs;
357: #endif
358: host.h_addr = hostaddr;
359: *((u_long *)host.h_addr) = inet_addr(p);
360: host.h_length = sizeof (u_long);
361: host.h_addrtype = AF_INET;
362: while (*cp == ' ' || *cp == '\t')
363: cp++;
364: host.h_name = cp;
365: q = host.h_aliases = host_aliases;
366: cp = strpbrk(cp, " \t");
367: if (cp != NULL)
368: *cp++ = '\0';
369: while (cp && *cp) {
370: if (*cp == ' ' || *cp == '\t') {
371: cp++;
372: continue;
373: }
374: if (q < &host_aliases[MAXALIASES - 1])
375: *q++ = cp;
376: cp = strpbrk(cp, " \t");
377: if (cp != NULL)
378: *cp++ = '\0';
379: }
380: *q = NULL;
381: return (&host);
382: }
383:
384: struct hostent *
385: _gethtbyname(name)
386: char *name;
387: {
388: register struct hostent *p;
389: register char **cp;
390:
391: _sethtent(0);
392: while (p = _gethtent()) {
393: if (strcasecmp(p->h_name, name) == 0)
394: break;
395: for (cp = p->h_aliases; *cp != 0; cp++)
396: if (strcasecmp(*cp, name) == 0)
397: goto found;
398: }
399: found:
400: _endhtent();
401: return (p);
402: }
403:
404: struct hostent *
405: _gethtbyaddr(addr, len, type)
406: char *addr;
407: int len, type;
408: {
409: register struct hostent *p;
410:
411: _sethtent(0);
412: while (p = _gethtent())
413: if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
414: break;
415: _endhtent();
416: return (p);
417: }
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