-.\" $Id$
.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
+.\" Copyright (C) 2004-2010 by Daniel Stenberg
.\"
.\" Permission to use, copy, modify, and distribute this
.\" software and its documentation for any purpose and without
.\" this software for any purpose. It is provided "as is"
.\" without express or implied warranty.
.\"
-.TH ARES_INIT 3 "21 July 1998"
+.TH ARES_INIT 3 "5 March 2010"
.SH NAME
ares_init, ares_init_options \- Initialize a resolver channel
.SH SYNOPSIS
.nf
.B #include <ares.h>
.PP
-.B int ares_init(ares_channel *\fIchannel\fP)
-.B int ares_init_options(ares_channel *\fIchannel\fP,
+.B int ares_init(ares_channel *\fIchannelptr\fP)
+.B int ares_init_options(ares_channel *\fIchannelptr\fP,
.B struct ares_options *\fIoptions\fP, int \fIoptmask\fP)
.PP
-.B cc file.c -lares
+.B cc file.c -lcares
.fi
.SH DESCRIPTION
-The
-.B ares_init
-function initializes a communications channel for name service
-lookups. If it returns successfully,
-.B ares_init
-will set the variable pointed to by
-.I channel
-to a handle used to identify the name service channel. The caller
-should invoke
+The \fBares_init\fP function initializes a communications channel for name
+service lookups. If it returns successfully, \fBares_init\fP will set the
+variable pointed to by \fIchannelptr\fP to a handle used to identify the name
+service channel. The caller should invoke
.BR ares_destroy (3)
on the handle when the channel is no longer needed.
.PP
-The
-.B ares_init_options
-function also initializes a name service channel, with additional
-options useful for applications requiring more control over name
-service configuration. The
-.I optmask
-parameter specifies which fields in the structure pointed to by
-.I options
-are set, as follows:
-.PP
+The \fBares_init_options\fP function also initializes a name service channel,
+with additional options useful for applications requiring more control over
+name service configuration. The \fIoptmask\fP parameter specifies which fields
+in the structure pointed to by \fIoptions\fP are set, as follows:
.TP 18
.B ARES_OPT_FLAGS
.B int \fIflags\fP;
.B ARES_OPT_TIMEOUT
.B int \fItimeout\fP;
.br
-The number of seconds each name server is given to respond to a query
-on the first try. (After the first try, the timeout algorithm becomes
-more complicated, but scales linearly with the value of
-\fItimeout\fP.) The default is five seconds.
+The number of seconds each name server is given to respond to a query on the
+first try. (After the first try, the timeout algorithm becomes more
+complicated, but scales linearly with the value of \fItimeout\fP.) The
+default is five seconds. This option is being deprecated by
+\fIARES_OPT_TIMEOUTMS\fP starting in c-ares 1.5.2.
+.TP 18
+.B ARES_OPT_TIMEOUTMS
+.B int \fItimeout\fP;
+.br
+The number of milliseconds each name server is given to respond to a query on
+the first try. (After the first try, the timeout algorithm becomes more
+complicated, but scales linearly with the value of \fItimeout\fP.) The
+default is five seconds. Note that this option is specified with the same
+struct field as the former \fIARES_OPT_TIMEOUT\fP, it is but the option bits
+that tell c-ares how to interpret the number. This option was added in c-ares
+1.5.2.
.TP 18
.B ARES_OPT_TRIES
.B int \fItries\fP;
.br
.B int \fInservers\fP;
.br
-The list of servers to contact, instead of the servers specified in
-resolv.conf or the local named.
+The list of IPv4 servers to contact, instead of the servers specified in
+resolv.conf or the local named. In order to allow specification of either
+IPv4 or IPv6 name servers, the
+.BR ares_set_servers(3)
+function must be used instead.
.TP 18
.B ARES_OPT_DOMAINS
.B char **\fIdomains\fP;
.B ARES_OPT_LOOKUPS
.B char *\fIlookups\fP;
.br
-The lookups to perform for host queries.
+The lookups to perform for host queries.
.I lookups
should be set to a string of the characters "b" or "f", where "b"
indicates a DNS lookup and "f" indicates a lookup in the hosts file.
+.TP 18
+.B ARES_OPT_SOCK_STATE_CB
+.B void (*\fIsock_state_cb\fP)(void *data, int s, int read, int write);
+.br
+.B void *\fIsock_state_cb_data\fP;
+.br
+A callback function to be invoked when a socket changes state.
+.I s
+will be passed the socket whose state has changed;
+.I read
+will be set to true if the socket should listen for read events, and
+.I write
+will be set to true if the socket should listen for write events.
+The value of
+.I sock_state_cb_data
+will be passed as the
+.I data
+argument.
.PP
The
.I flags
to TCP; simply continue on with the truncated response.
.TP 23
.B ARES_FLAG_NORECURSE
-Do not set the "recursion desired" bit on outgoing queries, so that
-the name server being contacted will not try to fetch the answer from
-other servers if it doesn't know the answer locally.
+Do not set the "recursion desired" bit on outgoing queries, so that the name
+server being contacted will not try to fetch the answer from other servers if
+it doesn't know the answer locally. Be aware that ares will not do the
+recursion for you. Recursion must be handled by the application calling ares
+if \fIARES_FLAG_NORECURSE\fP is set.
.TP 23
.B ARES_FLAG_STAYOPEN
-Do not close communciations sockets when the number of active queries
+Do not close communications sockets when the number of active queries
drops to zero.
.TP 23
.B ARES_FLAG_NOSEARCH
.TP 14
.B ARES_ENOMEM
The process's available memory was exhausted.
+.TP 14
+.B ARES_ENOTINITIALIZED
+c-ares library initialization not yet performed.
+.SH NOTES
+When initializing from
+.B /etc/resolv.conf,
+.BR ares_init (3)
+reads the
+.I domain
+and
+.I search
+directives to allow lookups of short names relative to the domains
+specified. The
+.I domain
+and
+.I search
+directives override one another. If more that one instance of either
+.I domain
+or
+.I search
+directives is specified, the last occurence wins. For more information,
+please see the
+.BR resolv.conf (5)
+manual page.
.SH SEE ALSO
-.BR ares_destroy (3)
+.BR ares_destroy(3),
+.BR ares_dup(3),
+.BR ares_library_init(3),
+.BR ares_set_servers(3)
.SH AUTHOR
Greg Hudson, MIT Information Systems
.br
Copyright 1998 by the Massachusetts Institute of Technology.
+.br
+Copyright (C) 2004-2010 by Daniel Stenberg.
projects / platform / upstream / c-ares.git / blobdiff