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.\" $Id$
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.\"
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.\" Copyright 2005 by Dominick Meglio.
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.\"
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.\" Permission to use, copy, modify, and distribute this
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.\" software and its documentation for any purpose and without
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.\" fee is hereby granted, provided that the above copyright
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.\" notice appear in all copies and that both that copyright
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.\" notice and this permission notice appear in supporting
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.\" documentation, and that the name of M.I.T. not be used in
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.\" advertising or publicity pertaining to distribution of the
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.\" software without specific, written prior permission.
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.\" M.I.T. makes no representations about the suitability of
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.\" this software for any purpose. It is provided "as is"
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.\" without express or implied warranty.
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.\"
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.TH ARES_GETNAMEINFO 3 "1 May 2009"
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.SH NAME
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ares_getnameinfo \- Address-to-nodename translation in protocol-independent manner
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.SH SYNOPSIS
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.nf
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.B #include <ares.h>
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.PP
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.B typedef void (*ares_nameinfo_callback)(void *\fIarg\fP, int \fIstatus\fP,
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.B int \fItimeouts\fP, char *\fInode\fP, char *\fIservice\fP)
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.PP
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.B void ares_getnameinfo(ares_channel \fIchannel\fP, const struct sockaddr *\fIsa\fP,
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.B ares_socklen_t \fIsalen\fP, int \fIflags\fP, ares_nameinfo_callback \fIcallback\fP,
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.B void *\fIarg\fP)
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.fi
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.SH DESCRIPTION
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The
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.B ares_getnameinfo
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function is defined for protocol-independent address translation. The function
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is a combination of \fIares_gethostbyaddr(3)\fP and \fIgetservbyport(3)\fP. The function will
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translate the address either by executing a host query on the name service channel
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identified by
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.IR channel
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or it will attempt to resolve it locally if possible.
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The parameters
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.I sa
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and
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.I len
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give the address as a sockaddr structure, and
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.I flags
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gives the options that the function will use. Valid flags are listed below:
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.TP 19
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.B ARES_NI_NOFQDN
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Only the nodename portion of the FQDN is returned for local hosts.
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.TP 19
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.B ARES_NI_NUMERICHOST
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The numeric form of the hostname is returned rather than the name.
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.TP 19
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.B ARES_NI_NAMEREQD
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An error is returned if the hostname cannot be found in the DNS.
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.TP 19
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.B ARES_NI_NUMERICSERV
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The numeric form of the service is returned rather than the name.
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.TP 19
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.B ARES_NI_TCP
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The service name is to be looked up for the TCP protocol.
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.TP 19
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.B ARES_NI_UDP
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The service name is to be looked up for the UDP protocol.
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.TP 19
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.B ARES_NI_SCTP
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The service name is to be looked up for the SCTP protocol.
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.TP 19
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.B ARES_NI_DCCP
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The service name is to be looked up for the DCCP protocol.
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.TP 19
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.B ARES_NI_NUMERICSCOPE
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The numeric form of the scope ID is returned rather than the name.
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.TP 19
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.B ARES_NI_LOOKUPHOST
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A hostname lookup is being requested.
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.TP 19
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.B ARES_NI_LOOKUPSERVICE
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A service name lookup is being requested.
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.PP
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When the query
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is complete or has
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failed, the ares library will invoke \fIcallback\fP. Completion or failure of
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the query may happen immediately, or may happen during a later call to
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\fIares_process(3)\fP, \fIares_destroy(3)\fP or \fIares_cancel(3)\fP.
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.PP
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The callback argument
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.I arg
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is copied from the
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.B ares_getnameinfo
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argument
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.IR arg .
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The callback argument
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.I status
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indicates whether the query succeeded and, if not, how it failed. It
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may have any of the following values:
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.TP 19
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.B ARES_SUCCESS
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The host lookup completed successfully.
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.TP 19
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.B ARES_ENOTIMP
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The ares library does not know how to look up addresses of type
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.IR family .
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.TP 19
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.B ARES_ENOTFOUND
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The address
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.I addr
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was not found.
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.TP 19
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.B ARES_ENOMEM
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Memory was exhausted.
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.TP 19
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.B ARES_EDESTRUCTION
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The name service channel
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.I channel
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is being destroyed; the query will not be completed.
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.TP 19
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.B ARES_EBADFLAGS
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The
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.I flags
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parameter contains an illegal value.
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.PP
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The callback argument
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.I timeouts
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reports how many times a query timed out during the execution of the
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given request.
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.PP
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On successful completion of the query, the callback argument
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.I node
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contains a string representing the hostname (assuming
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.B ARES_NI_LOOKUPHOST
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was specified). Additionally,
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.I service
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contains a string representing the service name (assuming
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.B ARES_NI_LOOKUPSERVICE
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was specified).
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If the query did not complete successfully, or one of the values
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was not requested,
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.I node
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or
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.I service
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will be
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.BR NULL .
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.SH SEE ALSO
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.BR ares_process (3),
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.BR ares_getaddrinfo (3)
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.SH AUTHOR
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Dominick Meglio
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.br
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Copyright 2005 by Dominick Meglio.
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