+++ /dev/null
-.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
-.\"
-.\" %%%LICENSE_START(VERBATIM)
-.\" Permission is granted to make and distribute verbatim copies of this
-.\" manual provided the copyright notice and this permission notice are
-.\" preserved on all copies.
-.\"
-.\" Permission is granted to copy and distribute modified versions of this
-.\" manual under the conditions for verbatim copying, provided that the
-.\" entire resulting derived work is distributed under the terms of a
-.\" permission notice identical to this one.
-.\"
-.\" Since the Linux kernel and libraries are constantly changing, this
-.\" manual page may be incorrect or out-of-date. The author(s) assume no
-.\" responsibility for errors or omissions, or for damages resulting from
-.\" the use of the information contained herein. The author(s) may not
-.\" have taken the same level of care in the production of this manual,
-.\" which is licensed free of charge, as they might when working
-.\" professionally.
-.\"
-.\" Formatted or processed versions of this manual, if unaccompanied by
-.\" the source, must acknowledge the copyright and authors of this work.
-.\" %%%LICENSE_END
-.\"
-.\" References consulted:
-.\" Linux libc source code
-.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
-.\" 386BSD man pages
-.\" Modified 1993-07-25 by Rik Faith (faith@cs.unc.edu)
-.\" Modified 2004-10-31 by aeb
-.\"
-.TH RESOLVER 3 2014-05-28 "GNU" "Linux Programmer's Manual"
-.SH NAME
-res_init, res_query, res_search, res_querydomain, res_mkquery, res_send,
-dn_comp, dn_expand \- resolver routines
-.SH SYNOPSIS
-.nf
-.B #include <netinet/in.h>
-.B #include <arpa/nameser.h>
-.B #include <resolv.h>
-.B extern struct __res_state _res;
-.sp
-.B int res_init(void);
-.sp
-.BI "int res_query(const char *" dname ", int " class ", int " type ,
-.RS
-.BI "unsigned char *" answer ", int " anslen );
-.RE
-.sp
-.BI "int res_search(const char *" dname ", int " class ", int " type ,
-.RS
-.BI "unsigned char *" answer ", int " anslen );
-.RE
-.sp
-.BI "int res_querydomain(const char *" name ", const char *" domain ,
-.RS
-.BI "int " class ", int " type ", unsigned char *" answer ,
-.BI "int " anslen );
-.RE
-.sp
-.BI "int res_mkquery(int " op ", const char *" dname ", int " class ,
-.RS
-.BI "int " type ", const unsigned char *" data ", int " datalen ,
-.BI "const unsigned char *" newrr ", unsigned char *" buf ", int " buflen );
-.RE
-.sp
-.BI "int res_send(const unsigned char *" msg ", int " msglen ,
-.RS
-.BI "unsigned char *" answer ", int " anslen );
-.RE
-.sp
-.BI "int dn_comp(const char *" exp_dn ", unsigned char *" comp_dn ,
-.RS
-.BI "int " length ", unsigned char **" dnptrs ", unsigned char **" lastdnptr );
-.RE
-.sp
-.BI "int dn_expand(const unsigned char *" msg ", const unsigned char *" eomorig ,
-.RS
-.BI "const unsigned char *" comp_dn ", char *" exp_dn ,
-.BI "int " length );
-.RE
-.fi
-.sp
-Link with \fI\-lresolv\fP.
-.SH DESCRIPTION
-These functions make queries to and interpret the responses from Internet
-domain name servers.
-.PP
-The
-.BR res_init ()
-function reads the configuration files (see
-.BR resolv.conf (5))
-to get the default domain name, search order and name
-server address(es).
-If no server is given, the local host is tried.
-If no domain is given, that associated with the local host is used.
-It can be overridden with the environment variable
-.BR LOCALDOMAIN .
-.BR res_init ()
-is normally executed by the first call to one of the
-other functions.
-.PP
-The
-.BR res_query ()
-function queries the name server for the
-fully qualified domain name \fIname\fP of specified \fItype\fP and
-\fIclass\fP.
-The reply is left in the buffer \fIanswer\fP of length
-\fIanslen\fP supplied by the caller.
-.PP
-The
-.BR res_search ()
-function makes a query and waits for the response
-like
-.BR res_query (),
-but in addition implements the default and search
-rules controlled by
-.B RES_DEFNAMES
-and
-.B RES_DNSRCH
-(see description of
-\fI_res\fP options below).
-.PP
-The
-.BR res_querydomain ()
-function makes a query using
-.BR res_query ()
-on the concatenation of \fIname\fP and \fIdomain\fP.
-.PP
-The following functions are lower-level routines used by
-.BR res_query ().
-.PP
-The
-.BR res_mkquery ()
-function constructs a query message in \fIbuf\fP
-of length \fIbuflen\fP for the domain name \fIdname\fP.
-The query type
-\fIop\fP is usually
-.BR QUERY ,
-but can be any of the types defined in
-\fI<arpa/nameser.h>\fP.
-\fInewrr\fP is currently unused.
-.PP
-The
-.BR res_send ()
-function sends a preformatted query given in
-\fImsg\fP of length \fImsglen\fP and returns the answer in \fIanswer\fP
-which is of length \fIanslen\fP.
-It will call
-.BR res_init (),
-if it
-has not already been called.
-.PP
-The
-.BR dn_comp ()
-function compresses the domain name \fIexp_dn\fP
-and stores it in the buffer \fIcomp_dn\fP of length \fIlength\fP.
-The compression uses an array of pointers \fIdnptrs\fP to previously
-compressed names in the current message.
-The first pointer points
-to the beginning of the message and the list ends with NULL.
-The limit of the array is specified by \fIlastdnptr\fP.
-If \fIdnptr\fP is NULL, domain names are not compressed.
-If \fIlastdnptr\fP is NULL, the list
-of labels is not updated.
-.PP
-The
-.BR dn_expand ()
-function expands the compressed domain name
-\fIcomp_dn\fP to a full domain name, which is placed in the buffer
-\fIexp_dn\fP of size \fIlength\fP.
-The compressed name is contained
-in a query or reply message, and \fImsg\fP points to the beginning of
-the message.
-.PP
-The resolver routines use global configuration and state information
-contained in the structure \fI_res\fP, which is defined in
-\fI<resolv.h>\fP.
-The only field that is normally manipulated by the
-user is \fI_res.options\fP.
-This field can contain the bitwise "OR"
-of the following options:
-.TP
-.B RES_INIT
-True if
-.BR res_init ()
-has been called.
-.TP
-.B RES_DEBUG
-Print debugging messages.
-This option is available only if glibc was built with debugging enabled,
-.\" See resolv/README.
-.\" Support for RES_DEBUG was made conditional in glibc 2.2.
-which is not the default.
-.TP
-.B RES_AAONLY
-Accept authoritative answers only.
-.BR res_send ()
-continues until
-it finds an authoritative answer or returns an error. [Not currently
-implemented].
-.TP
-.B RES_USEVC
-Use TCP connections for queries rather than UDP datagrams.
-.TP
-.B RES_PRIMARY
-Query primary domain name server only.
-.TP
-.B RES_IGNTC
-Ignore truncation errors.
-Don't retry with TCP. [Not currently
-implemented].
-.TP
-.B RES_RECURSE
-Set the recursion desired bit in queries.
-Recursion is carried out
-by the domain name server, not by
-.BR res_send ().
-[Enabled by default].
-.TP
-.B RES_DEFNAMES
-If set,
-.BR res_search ()
-will append the default domain name to
-single component names\(emthat is, those that do not contain a dot.
-[Enabled by default].
-.TP
-.B RES_STAYOPEN
-Used with
-.B RES_USEVC
-to keep the TCP connection open between queries.
-.TP
-.B RES_DNSRCH
-If set,
-.BR res_search ()
-will search for hostnames in the current
-domain and in parent domains.
-This option is used by
-.BR gethostbyname (3).
-[Enabled by default].
-.PP
-This list is not complete.
-You can find some other flags described in
-.BR resolv.conf (5).
-.SH RETURN VALUE
-The
-.BR res_init ()
-function returns 0 on success, or \-1 if an error
-occurs.
-.PP
-The
-.BR res_query (),
-.BR res_search (),
-.BR res_querydomain (),
-.BR res_mkquery ()
-and
-.BR res_send ()
-functions return the length
-of the response, or \-1 if an error occurs.
-.PP
-The
-.BR dn_comp ()
-and
-.BR dn_expand ()
-functions return the length
-of the compressed name, or \-1 if an error occurs.
-.SH FILES
-.nf
-/etc/resolv.conf resolver configuration file
-/etc/host.conf resolver configuration file
-.fi
-.SH CONFORMING TO
-4.3BSD.
-.SH SEE ALSO
-.BR gethostbyname (3),
-.BR resolv.conf (5),
-.BR resolver (5),
-.BR hostname (7),
-.BR named (8)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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