ARES_CREATE_QUERY
Section: C Library Functions (3)
Updated: 17 Aug 2012
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NAME
ares_create_query - Compose a single-question DNS query buffer
SYNOPSIS
#include <ares.h>
int ares_create_query(const char *name, int dnsclass, int type,
DESCRIPTION
The
ares_create_query
function composes a DNS query with a single question.
The parameter
name
gives the query name as a NUL-terminated C string of period-separated
labels optionally ending with a period; periods and backslashes within
a label must be escaped with a backlash. The parameters
dnsclass
and
type
give the class and type of the query using the values defined in
<arpa/nameser.h>.
The parameter
id
gives a 16-bit identifier for the query. The parameter
rd
should be nonzero if recursion is desired, zero if not. The query
will be placed in an allocated buffer, a pointer to which will be
stored in the variable pointed to by
buf,
and the length of which will be stored in the variable pointed to by
buflen.
It is the caller's responsibility to free this buffer using
ares_free_string(3) when it is no longer needed.
The parameter
max_udp_size
should be nonzero to activate EDNS. Usage of ares_create_query(3) with
max_udp_size
set to zero is equivalent to ares_mkquery(3).
RETURN VALUES
ares_create_query
can return any of the following values:
- ARES_SUCCESS
-
Construction of the DNS query succeeded.
- ARES_EBADNAME
-
The query name
name
could not be encoded as a domain name, either because it contained a
zero-length label or because it contained a label of more than 63
characters.
- ARES_ENOMEM
-
Memory was exhausted.
AVAILABILITY
Added in c-ares 1.10.0
SEE ALSO
ares_expand_name(3),
ares_free_string(3)
AUTHOR
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUES
-
- AVAILABILITY
-
- SEE ALSO
-
- AUTHOR
-