2 * Copyright (c) 1985, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
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14 * may be used to endorse or promote products derived from this software
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29 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
31 * Permission to use, copy, modify, and distribute this software for any
32 * purpose with or without fee is hereby granted, provided that the above
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34 * the name of Digital Equipment Corporation not be used in advertising or
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49 * @(#)gethostnamadr.c 8.1 (Berkeley) 6/4/93
50 * $FreeBSD: src/lib/libc/net/getnetbydns.c,v 1.13.2.4 2002/10/11 11:07:13 ume Exp $
51 * $DragonFly: src/lib/libc/net/getnetbydns.c,v 1.5 2005/11/13 02:04:47 swildner Exp $
53 /* Portions Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
54 * Dep. Matematica Universidade de Coimbra, Portugal, Europe
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.
61 #include <sys/param.h>
62 #include <sys/socket.h>
63 #include <netinet/in.h>
64 #include <arpa/inet.h>
65 #include <arpa/nameser.h>
76 #include "res_config.h"
84 #define MAXPACKET (64*1024)
88 u_char buf[MAXPACKET];
96 static struct netent *
97 getnetanswer(querybuf *answer, int anslen, int net_i)
104 int type, class, buflen, ancount, qdcount, haveanswer, i, nchar;
105 char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN];
106 char *in, *st, *pauxt, *bp, **ap;
107 char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;
108 static struct netent net_entry;
109 static char *net_aliases[MAXALIASES], netbuf[PACKETSZ];
112 * find first satisfactory answer
114 * answer --> +------------+ ( MESSAGE )
117 * | Question | the question for the name server
119 * | Answer | RRs answering the question
121 * | Authority | RRs pointing toward an authority
122 * | Additional | RRs holding additional information
125 eom = answer->buf + anslen;
127 ancount = ntohs(hp->ancount); /* #/records in the answer section */
128 qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
130 buflen = sizeof(netbuf);
131 cp = answer->buf + HFIXEDSZ;
134 h_errno = HOST_NOT_FOUND;
139 while (qdcount-- > 0)
140 cp += __dn_skipname(cp, eom) + QFIXEDSZ;
143 net_entry.n_aliases = net_aliases;
145 while (--ancount >= 0 && cp < eom) {
146 n = dn_expand(answer->buf, eom, cp, bp, buflen);
147 if ((n < 0) || !res_dnok(bp))
151 strncpy(&ans[0], bp, sizeof(ans) - 1);
152 ans[sizeof(ans) - 1] = '\0';
155 cp += INT32SZ; /* TTL */
157 if (class == C_IN && type == T_PTR) {
158 n = dn_expand(answer->buf, eom, cp, bp, buflen);
159 if ((n < 0) || !res_hnok(bp)) {
168 net_entry.n_addrtype =
169 (class == C_IN) ? AF_INET : AF_UNSPEC;
177 net_entry.n_name = *net_entry.n_aliases;
178 net_entry.n_net = 0L;
181 in = *net_entry.n_aliases;
182 net_entry.n_name = &ans[0];
184 for (i = 0; i < 4; i++) {
185 for (st = in, nchar = 0;
189 if (nchar != 1 || *in != '0' || flag) {
191 strncpy(paux1, (i==0) ? in : in-1,
192 (i==0) ? nchar : nchar+1);
193 paux1[(i==0) ? nchar : nchar+1] = '\0';
195 paux2 = strcat(paux1, paux2);
200 net_entry.n_net = inet_network(paux2);
203 net_entry.n_aliases++;
211 _getnetbydnsaddr(unsigned long net, int net_type)
213 unsigned int netbr[4];
218 struct netent *net_entry;
220 if (net_type != AF_INET)
223 for (nn = 4, net2 = net; net2; net2 >>= 8)
224 netbr[--nn] = net2 & 0xff;
226 case 3: /* Class A */
227 sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);
229 case 2: /* Class B */
230 sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);
232 case 1: /* Class C */
233 sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
236 case 0: /* Class D - E */
237 sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
241 if ((buf = malloc(sizeof(*buf))) == NULL) {
242 h_errno = NETDB_INTERNAL;
245 anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)buf, sizeof(*buf));
249 if (_res.options & RES_DEBUG)
250 printf("res_search failed\n");
253 } else if (anslen > sizeof(*buf)) {
256 if (_res.options & RES_DEBUG)
257 printf("res_search static buffer too small\n");
261 net_entry = getnetanswer(buf, anslen, BYADDR);
264 unsigned u_net = net; /* maybe net should be unsigned ? */
266 /* Strip trailing zeros */
267 while ((u_net & 0xff) == 0 && u_net != 0)
269 net_entry->n_net = u_net;
276 _getnetbydnsname(const char *net)
281 struct netent *net_entry;
283 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
284 h_errno = NETDB_INTERNAL;
287 if ((buf = malloc(sizeof(*buf))) == NULL) {
288 h_errno = NETDB_INTERNAL;
291 strncpy(qbuf, net, sizeof(qbuf) - 1);
292 qbuf[sizeof(qbuf) - 1] = '\0';
293 anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)buf, sizeof(*buf));
297 if (_res.options & RES_DEBUG)
298 printf("res_search failed\n");
301 } else if (anslen > sizeof(*buf)) {
304 if (_res.options & RES_DEBUG)
305 printf("res_search static buffer too small\n");
309 net_entry = getnetanswer(buf, anslen, BYNAME);
315 _setnetdnsent(int stayopen)
318 _res.options |= RES_STAYOPEN | RES_USEVC;
324 _res.options &= ~(RES_STAYOPEN | RES_USEVC);