bionic (3) ares_create_query.3.gz

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_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

                                                   17 Aug 2012                              ARES_CREATE_QUERY(3)