.\"

.\" Copyright 1998 by the Massachusetts Institute of Technology.

.\"

.\" Permission to use, copy, modify, and distribute this

.\" software and its documentation for any purpose and without

.\" fee is hereby granted, provided that the above copyright

.\" notice appear in all copies and that both that copyright

.\" notice and this permission notice appear in supporting

.\" documentation, and that the name of M.I.T. not be used in

.\" advertising or publicity pertaining to distribution of the

.\" software without specific, written prior permission.

.\" M.I.T. makes no representations about the suitability of

.\" this software for any purpose.  It is provided "as is"

.\" without express or implied warranty.

.\"

.TH ARES_SEARCH 3 "24 July 1998"

.SH NAME

ares_search \- Initiate a DNS query with domain search

.SH SYNOPSIS

.nf

.B #include <ares.h>

.PP

.B typedef void (*ares_callback)(void *\fIarg\fP, int \fIstatus\fP,

.B	int \fItimeouts\fP, unsigned char *\fIabuf\fP, int \fIalen\fP)

.PP

.B void ares_search(ares_channel \fIchannel\fP, const char *\fIname\fP,

.B 	int \fIdnsclass\fP, int \fItype\fP, ares_callback \fIcallback\fP,

.B	void *\fIarg\fP)

.fi

.SH DESCRIPTION

The

.B ares_search

function initiates a series of single-question DNS queries on the name

service channel identified by

.IR channel ,

using the channel's search domains as well as a host alias file given

by the HOSTALIAS environment variable.  The parameter

.I name

gives the alias name or the base of the query name as a NUL-terminated

C string of period-separated labels; if it ends with a period, the

channel's search domains will not be used.  Periods and backslashes

within a label must be escaped with a backslash.  The parameters

.I dnsclass

and

.I type

give the class and type of the query using the values defined in

.BR <arpa/nameser.h> .

When the query sequence is complete or has failed, the ares library

will invoke

.IR callback .

Completion or failure of the query sequence may happen immediately, or

may happen during a later call to

.BR ares_process (3)

or

.BR ares_destroy (3).

.PP

The callback argument

.I arg

is copied from the

.B ares_search

argument

.IR arg .

The callback argument

.I status

indicates whether the query sequence ended with a successful query

and, if not, how the query sequence failed.  It may have any of the

following values:

.TP 19

.B ARES_SUCCESS

A query completed successfully.

.TP 19

.B ARES_ENODATA

No query completed successfully; when the query was tried without a

search domain appended, a response was returned with no answers.

.TP 19

.B ARES_EFORMERR

A query completed but the server claimed that the query was

malformatted.

.TP 19

.B ARES_ESERVFAIL

No query completed successfully; when the query was tried without a

search domain appended, the server claimed to have experienced a

failure.  (This code can only occur if the

.B ARES_FLAG_NOCHECKRESP

flag was specified at channel initialization time; otherwise, such

responses are ignored at the

.BR ares_send (3)

level.)

.TP 19

.B ARES_ENOTFOUND

No query completed successfully; when the query was tried without a

search domain appended, the server reported that the queried-for

domain name was not found.

.TP 19

.B ARES_ENOTIMP

A query completed but the server does not implement the operation

requested by the query.  (This code can only occur if the

.B ARES_FLAG_NOCHECKRESP

flag was specified at channel initialization time; otherwise, such

responses are ignored at the

.BR ares_send (3)

level.)

.TP 19

.B ARES_EREFUSED

A query completed but the server refused the query.  (This code can

only occur returned if the

.B ARES_FLAG_NOCHECKRESP

flag was specified at channel initialization time; otherwise, such

responses are ignored at the

.BR ares_send (3)

level.)

.TP 19

.B ARES_TIMEOUT

No name servers responded to a query within the timeout period.

.TP 19

.B ARES_ECONNREFUSED

No name servers could be contacted.

.TP 19

.B ARES_ENOMEM

Memory was exhausted.

.TP 19

.B ARES_ECANCELLED

The query was cancelled.

.TP 19

.B ARES_EDESTRUCTION

The name service channel

.I channel

is being destroyed; the query will not be completed.

.PP

The callback argument

.I timeouts

reports how many times a query timed out during the execution of the

given request.

.PP

If a query completed successfully, the callback argument

.I abuf

points to a result buffer of length

.IR alen .

If the query did not complete successfully,

.I abuf

will usually be NULL and

.I alen

will usually be 0, but in some cases an unsuccessful query result may

be placed in

.IR abuf .

.SH SEE ALSO

.BR ares_process (3)

.SH AUTHOR

Greg Hudson, MIT Information Systems

.br

Copyright 1998 by the Massachusetts Institute of Technology.