Commit | Line | Data |
---|---|---|
345feb69 KB |
1 | /* |
2 | * Copyright (c) 1988 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms are permitted | |
ca67e7b4 C |
6 | * provided that this notice is preserved and that due credit is given |
7 | * to the University of California at Berkeley. The name of the University | |
8 | * may not be used to endorse or promote products derived from this | |
9 | * software without specific prior written permission. This software | |
10 | * is provided ``as is'' without express or implied warranty. | |
345feb69 KB |
11 | */ |
12 | ||
13 | #if defined(LIBC_SCCS) && !defined(lint) | |
ca67e7b4 | 14 | static char sccsid[] = "@(#)res_query.c 5.4 (Berkeley) 4/21/88"; |
345feb69 KB |
15 | #endif /* LIBC_SCCS and not lint */ |
16 | ||
17 | #include <sys/param.h> | |
18 | #include <sys/socket.h> | |
19 | #include <netinet/in.h> | |
20 | #include <ctype.h> | |
21 | #include <netdb.h> | |
22 | #include <stdio.h> | |
23 | #include <errno.h> | |
24 | #include <strings.h> | |
25 | #include <arpa/inet.h> | |
26 | #include <arpa/nameser.h> | |
27 | #include <resolv.h> | |
28 | ||
29 | #if PACKETSZ > 1024 | |
30 | #define MAXPACKET PACKETSZ | |
31 | #else | |
32 | #define MAXPACKET 1024 | |
33 | #endif | |
34 | ||
35 | extern int errno; | |
36 | int h_errno; | |
37 | ||
38 | /* | |
39 | * Formulate a normal query, send, and await answer. | |
40 | * Returned answer is placed in supplied buffer "answer". | |
41 | * Perform preliminary check of answer, returning success only | |
42 | * if no error is indicated and the answer count is nonzero. | |
43 | * Return the size of the response on success, -1 on error. | |
44 | * Error number is left in h_errno. | |
a5e08740 | 45 | * Caller must parse answer and determine whether it answers the question. |
345feb69 KB |
46 | */ |
47 | res_query(name, class, type, answer, anslen) | |
48 | char *name; /* domain name */ | |
49 | int class, type; /* class and type of query */ | |
50 | u_char *answer; /* buffer to put answer */ | |
51 | int anslen; /* size of answer buffer */ | |
52 | { | |
53 | char buf[MAXPACKET]; | |
54 | HEADER *hp; | |
55 | int n; | |
56 | ||
57 | if ((_res.options & RES_INIT) == 0 && res_init() == -1) | |
58 | return (-1); | |
59 | #ifdef DEBUG | |
60 | if (_res.options & RES_DEBUG) | |
61 | printf("res_query(%s, %d, %d)\n", name, class, type); | |
62 | #endif | |
63 | n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL, | |
64 | buf, sizeof(buf)); | |
65 | ||
66 | if (n <= 0) { | |
67 | #ifdef DEBUG | |
68 | if (_res.options & RES_DEBUG) | |
69 | printf("res_query: mkquery failed\n"); | |
70 | #endif | |
71 | h_errno = NO_RECOVERY; | |
72 | return (n); | |
73 | } | |
74 | n = res_send(buf, n, answer, anslen); | |
75 | if (n < 0) { | |
76 | #ifdef DEBUG | |
77 | if (_res.options & RES_DEBUG) | |
78 | printf("res_query: send error\n"); | |
79 | #endif | |
80 | h_errno = TRY_AGAIN; | |
81 | return(n); | |
82 | } | |
83 | ||
84 | hp = (HEADER *) answer; | |
85 | if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { | |
86 | #ifdef DEBUG | |
87 | if (_res.options & RES_DEBUG) | |
88 | printf("rcode = %d, ancount=%d\n", hp->rcode, | |
89 | ntohs(hp->ancount)); | |
90 | #endif | |
91 | switch (hp->rcode) { | |
92 | case NXDOMAIN: | |
a5e08740 | 93 | h_errno = HOST_NOT_FOUND; |
345feb69 KB |
94 | break; |
95 | case SERVFAIL: | |
96 | h_errno = TRY_AGAIN; | |
97 | break; | |
98 | case NOERROR: | |
d7ec9b41 | 99 | h_errno = NO_DATA; |
345feb69 KB |
100 | break; |
101 | case FORMERR: | |
102 | case NOTIMP: | |
103 | case REFUSED: | |
a5e08740 | 104 | default: |
345feb69 | 105 | h_errno = NO_RECOVERY; |
a5e08740 | 106 | break; |
345feb69 KB |
107 | } |
108 | return (-1); | |
109 | } | |
110 | return(n); | |
111 | } | |
112 | ||
113 | /* | |
114 | * Formulate a normal query, send, and retrieve answer in supplied buffer. | |
115 | * Return the size of the response on success, -1 on error. | |
116 | * If enabled, implement search rules until answer or unrecoverable failure | |
117 | * is detected. Error number is left in h_errno. | |
118 | * Only useful for queries in the same name hierarchy as the local host | |
119 | * (not, for example, for host address-to-name lookups in domain in-addr.arpa). | |
120 | */ | |
121 | res_search(name, class, type, answer, anslen) | |
122 | char *name; /* domain name */ | |
123 | int class, type; /* class and type of query */ | |
124 | u_char *answer; /* buffer to put answer */ | |
125 | int anslen; /* size of answer */ | |
126 | { | |
127 | register char *cp, **domain; | |
d7ec9b41 | 128 | int n, ret, got_nodata = 0; |
345feb69 KB |
129 | char *hostalias(); |
130 | ||
131 | if ((_res.options & RES_INIT) == 0 && res_init() == -1) | |
132 | return (-1); | |
133 | ||
134 | errno = 0; | |
d7ec9b41 | 135 | h_errno = HOST_NOT_FOUND; /* default, if we never query */ |
345feb69 KB |
136 | for (cp = name, n = 0; *cp; cp++) |
137 | if (*cp == '.') | |
138 | n++; | |
139 | if (n == 0 && (cp = hostalias(name))) | |
140 | return (res_query(cp, class, type, answer, anslen)); | |
141 | ||
ca67e7b4 C |
142 | if ((n == 0 || *--cp != '.') && (_res.options & RES_DEFNAMES)) |
143 | for (domain = _res.dnsrch; *domain; domain++) { | |
345feb69 KB |
144 | ret = res_querydomain(name, *domain, class, type, |
145 | answer, anslen); | |
146 | if (ret > 0) | |
147 | return (ret); | |
148 | /* | |
149 | * If no server present, give up. | |
150 | * If name isn't found in this domain, | |
151 | * keep trying higher domains in the search list | |
152 | * (if that's enabled). | |
d7ec9b41 | 153 | * On a NO_DATA error, keep trying, otherwise |
345feb69 KB |
154 | * a wildcard entry of another type could keep us |
155 | * from finding this entry higher in the domain. | |
ca67e7b4 C |
156 | * If we get some other error (non-authoritative negative |
157 | * answer or server failure), then stop searching up, | |
345feb69 KB |
158 | * but try the input name below in case it's fully-qualified. |
159 | */ | |
160 | if (errno == ECONNREFUSED) { | |
161 | h_errno = TRY_AGAIN; | |
162 | return (-1); | |
163 | } | |
d7ec9b41 MK |
164 | if (h_errno == NO_DATA) |
165 | got_nodata++; | |
166 | if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) || | |
345feb69 KB |
167 | (_res.options & RES_DNSRCH) == 0) |
168 | break; | |
345feb69 KB |
169 | } |
170 | /* | |
171 | * If the search/default failed, try the name as fully-qualified, | |
172 | * but only if it contained at least one dot (even trailing). | |
173 | */ | |
ca67e7b4 C |
174 | if (n) |
175 | return (res_querydomain(name, (char *)NULL, class, type, | |
176 | answer, anslen)); | |
d7ec9b41 MK |
177 | if (got_nodata) |
178 | h_errno = NO_DATA; | |
345feb69 KB |
179 | return (-1); |
180 | } | |
181 | ||
182 | /* | |
183 | * Perform a call on res_query on the concatenation of name and domain, | |
184 | * removing a trailing dot from name if domain is NULL. | |
185 | */ | |
186 | res_querydomain(name, domain, class, type, answer, anslen) | |
187 | char *name, *domain; | |
188 | int class, type; /* class and type of query */ | |
189 | u_char *answer; /* buffer to put answer */ | |
190 | int anslen; /* size of answer */ | |
191 | { | |
192 | char nbuf[2*MAXDNAME+2]; | |
193 | char *longname = nbuf; | |
194 | int n; | |
195 | ||
d7ec9b41 MK |
196 | #ifdef DEBUG |
197 | if (_res.options & RES_DEBUG) | |
198 | printf("res_querydomain(%s, %s, %d, %d)\n", | |
199 | name, domain, class, type); | |
200 | #endif | |
345feb69 KB |
201 | if (domain == NULL) { |
202 | /* | |
203 | * Check for trailing '.'; | |
204 | * copy without '.' if present. | |
205 | */ | |
206 | n = strlen(name) - 1; | |
207 | if (name[n] == '.' && n < sizeof(nbuf) - 1) { | |
208 | bcopy(name, nbuf, n); | |
209 | nbuf[n] = '\0'; | |
210 | } else | |
211 | longname = name; | |
212 | } else | |
213 | (void)sprintf(nbuf, "%.*s.%.*s", | |
214 | MAXDNAME, name, MAXDNAME, domain); | |
215 | ||
216 | return (res_query(longname, class, type, answer, anslen)); | |
217 | } | |
218 | ||
219 | char * | |
220 | hostalias(name) | |
221 | register char *name; | |
222 | { | |
223 | register char *C1, *C2; | |
224 | FILE *fp; | |
225 | char *file, *getenv(), *strcpy(), *strncpy(); | |
226 | char buf[BUFSIZ]; | |
227 | static char abuf[MAXDNAME]; | |
228 | ||
229 | file = getenv("HOSTALIASES"); | |
230 | if (file == NULL || (fp = fopen(file, "r")) == NULL) | |
231 | return (NULL); | |
232 | buf[sizeof(buf) - 1] = '\0'; | |
233 | while (fgets(buf, sizeof(buf), fp)) { | |
234 | for (C1 = buf; *C1 && !isspace(*C1); ++C1); | |
235 | if (!*C1) | |
236 | break; | |
237 | *C1 = '\0'; | |
238 | if (!strcasecmp(buf, name)) { | |
239 | while (isspace(*++C1)); | |
240 | if (!*C1) | |
241 | break; | |
242 | for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2); | |
243 | abuf[sizeof(abuf) - 1] = *C2 = '\0'; | |
244 | (void)strncpy(abuf, C1, sizeof(abuf) - 1); | |
245 | fclose(fp); | |
246 | return (abuf); | |
247 | } | |
248 | } | |
249 | fclose(fp); | |
250 | return (NULL); | |
251 | } |