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,
unsigned short id,
int rd,
unsigned char **buf,
int *buflen,
int max_udp_size)
DESCRIPTION
The
ares_create_query(3) 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 using ares_mkquery(3).
RETURN VALUES
ares_create_query
can return any of the following values:
- ARES_SUCCESS
-
Construction of the DNS query succeeded.
- ARES_ENOTFOUND
-
The query name
name
refers to a
.onion
domain name. See RFC 7686.
- 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),
ares_mkquery(3)
AUTHOR