@comment The start of a comment is indicated by the following comment. This
@comment syntax is used by the script funcstxh.sh: @comment function <name>

@comment function res_query

@node res_query, resolver
@findex res_query

@c This file was originally a Linux man page - see the copyright below. It
@c was modified for use in libsocket by Richard Dawe <richdawe@bigfoot.com>.

@c Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
@c
@c Permission is granted to make and distribute verbatim copies of this
@c manual provided the copyright notice and this permission notice are
@c preserved on all copies.
@c
@c Permission is granted to copy and distribute modified versions of this
@c manual under the conditions for verbatim copying, provided that the
@c entire resulting derived work is distributed under the terms of a
@c permission notice identical to this one
@c 
@c Since the Linux kernel and libraries are constantly changing, this
@c manual page may be incorrect or out-of-date.  The author(s) assume no
@c responsibility for errors or omissions, or for damages resulting from
@c the use of the information contained herein.  The author(s) may not
@c have taken the same level of care in the production of this manual,
@c which is licensed free of charge, as they might when working
@c professionally.
@c 
@c Formatted or processed versions of this manual, if unaccompanied by
@c the source, must acknowledge the copyright and authors of this work.
@c
@c References consulted:
@c     Linux libc source code
@c     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
@c     386BSD man pages
@c Modified Sun Jul 25 11:01:53 1993 by Rik Faith (faith@cs.unc.edu)

@example
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>

extern struct state _res;

int res_query (const char *dname, int class, int type,
               unsigned char *answer, int anslen);
@end example

@subheading Description

The @code{res_query()} function queries the name server for the
fully-qualified domain name @var{name} of specified @var{type} and
@var{class}.  The reply is left in the buffer @var{answer} of length
@var{anslen} supplied by the caller.

The resolver routines use global configuration and state information
contained in the structure @samp{_res}, which is defined in 
@samp{<resolv.h>}.  The only field that is normally manipulated by the 
user is @samp{_res.options}.  This field can contain the bitwise OR
of the following options:

@vtable @samp
@item RES_INIT
True if @code{res_init()} has been called.

@item RES_DEBUG
Print debugging messages.

@item RES_AAONLY
Accept authoritative answers only.  @code{res_send()} continues until
it fins an authoritative answer or returns an error.  [Not currently
implemented].

@item RES_USEVC
Use TCP connections for queries rather than UDP datagrams.

@item RES_PRIMARY
Query primary domain name server only.

@item RES_IGNTC
Ignore truncation errors.  Don't retry with TCP.  [Not currently
implemented].

@item RES_RECURSE
Set the recursion desired bit in queries.  Recursion is carried out
by the domain name server, not by @code{res_send()}.  [Enabled by 
default].

@item RES_DEFNAMES
If set, @code{res_search()} will append the default domain name to
single component names, ie. those that do not contain a dot.
[Enabled by default].

@item RES_STAYOPEN
Used with RES_USEVC to keep the TCP connection open between queries.

@item RES_DNSRCH
If set, @code{res_search()} will search for host names in the current
domain and in parent domains.  This option is used by @code{gethostbyname()}
(@pxref{gethostbyname}). [Enabled by default].
@end vtable

@subheading Return Value

@code{res_query()} returns the length of the response, or -1 if an error
occurs.

@subheading Portability

This function is not portable.  It is taken from Linux's libc 5 and so may be
portable to Linux.

@subheading Example

@example
@end example