1 /* Copyright (C) 2004-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
24 #include <arpa/nameser.h>
29 # define MAXPACKET PACKETSZ
31 # define MAXPACKET 65536
35 /* We need this time later. */
36 typedef union querybuf
39 unsigned char buf
[MAXPACKET
];
43 static const short int qtypes
[] = { ns_t_a
, ns_t_aaaa
};
44 #define nqtypes (sizeof (qtypes) / sizeof (qtypes[0]))
48 _nss_dns_getcanonname_r (const char *name
, char *buffer
, size_t buflen
,
49 char **result
,int *errnop
, int *h_errnop
)
51 /* Just an alibi buffer, res_nquery will allocate a real buffer for
53 unsigned char buf
[20];
58 } ansp
= { .ptr
= buf
};
59 enum nss_status status
= NSS_STATUS_UNAVAIL
;
61 for (int i
= 0; i
< nqtypes
; ++i
)
63 int r
= __libc_res_nquery (&_res
, name
, ns_c_in
, qtypes
[i
],
64 buf
, sizeof (buf
), &ansp
.ptr
, NULL
, NULL
,
68 /* We need to decode the response. Just one question record.
69 And if we got no answers we bail out, too. */
70 if (ansp
.buf
->hdr
.qdcount
!= htons (1))
73 /* Number of answers. */
74 unsigned int ancount
= ntohs (ansp
.buf
->hdr
.ancount
);
76 /* Beginning and end of the buffer with query, answer, and the
78 unsigned char *ptr
= &ansp
.buf
->buf
[sizeof (HEADER
)];
79 unsigned char *endptr
= ansp
.ptr
+ r
;
81 /* Skip over the query. This is the name, type, and class. */
82 int s
= __dn_skipname (ptr
, endptr
);
86 status
= NSS_STATUS_UNAVAIL
;
90 /* Skip over the name and the two 16-bit values containing type
92 ptr
+= s
+ 2 * sizeof (uint16_t);
96 /* Now the reply. First again the name from the query,
97 then type, class, TTL, and the length of the RDATA.
98 We remember the name start. */
99 unsigned char *namestart
= ptr
;
100 s
= __dn_skipname (ptr
, endptr
);
106 /* Check that there are enough bytes for the RR
108 if (endptr
- ptr
< 10)
111 /* Check whether type and class match. */
113 NS_GET16 (type
, ptr
);
114 if (type
== qtypes
[i
])
116 /* We found the record. */
117 s
= __dn_expand (ansp
.buf
->buf
, endptr
, namestart
,
121 if (errno
!= EMSGSIZE
)
124 /* The buffer is too small. */
126 status
= NSS_STATUS_TRYAGAIN
;
127 h_errno
= NETDB_INTERNAL
;
133 status
= NSS_STATUS_SUCCESS
;
139 if (type
!= ns_t_cname
)
142 if (__ns_get16 (ptr
) != ns_c_in
)
145 /* Also skip over class and TTL. */
146 ptr
+= sizeof (uint16_t) + sizeof (uint32_t);
148 /* Skip over RDATA length and RDATA itself. */
149 uint16_t rdatalen
= __ns_get16 (ptr
);
150 ptr
+= sizeof (uint16_t);
151 /* Not enough room for RDATA. */
152 if (endptr
- ptr
< rdatalen
)
158 /* Restore original buffer before retry. */