mirror of https://github.com/c-ares/c-ares.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
104 lines
2.9 KiB
104 lines
2.9 KiB
21 years ago
|
.\" $Id$
|
||
|
|
.\"
|
||
|
|
.\" 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_GETHOSTBYNAME 3 "25 July 1998"
|
||
|
|
.SH NAME
|
||
|
|
ares_gethostbyname \- Initiate a host query by name
|
||
|
|
.SH SYNOPSIS
|
||
|
|
.nf
|
||
|
|
.B #include <ares.h>
|
||
|
|
.PP
|
||
|
|
.B typedef void (*ares_host_callback)(void *\fIarg\fP, int \fIstatus\fP,
|
||
|
|
.B struct hostent *\fIhostent\fP)
|
||
|
|
.PP
|
||
|
|
.B void ares_gethostbyname(ares_channel \fIchannel\fP, const char *\fIname\fP,
|
||
|
|
.B int \fIfamily\fP, ares_host_callback \fIcallback\fP, void *\fIarg\fP)
|
||
|
|
.fi
|
||
|
|
.SH DESCRIPTION
|
||
|
|
The
|
||
|
|
.B ares_gethostbyname
|
||
|
|
function initiates a host query by name on the name service channel
|
||
|
|
identified by
|
||
|
|
.IR channel .
|
||
|
|
The parameter
|
||
|
|
.I name
|
||
|
|
gives the hostname as a NUL-terminated C string, and
|
||
|
|
.I family
|
||
|
|
gives the desired type of address for the resulting host entry. When
|
||
|
|
the query is complete or has failed, the ares library will invoke
|
||
|
|
.IR callback .
|
||
|
|
Completion or failure of the query 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_gethostbyname
|
||
|
|
argument
|
||
|
|
.IR arg .
|
||
|
|
The callback argument
|
||
|
|
.I status
|
||
|
|
indicates whether the query succeeded and, if not, how it failed. It
|
||
|
|
may have any of the following values:
|
||
|
|
.TP 19
|
||
|
|
.B ARES_SUCCESS
|
||
|
|
The host lookup completed successfully.
|
||
|
|
.TP 19
|
||
|
|
.B ARES_ENOTIMP
|
||
|
|
The ares library does not know how to find addresses of type
|
||
|
|
.IR family .
|
||
|
|
.TP 19
|
||
|
|
.B ARES_EBADNAME
|
||
|
|
The hostname
|
||
|
|
.B name
|
||
|
|
is composed entirely of numbers and periods, but is not a valid
|
||
|
|
representation of an Internet address.
|
||
|
|
.TP 19
|
||
|
|
.B ARES_ENOTFOUND
|
||
|
|
The address
|
||
|
|
.I addr
|
||
|
|
was not found.
|
||
|
|
.TP 19
|
||
|
|
.B ARES_ENOMEM
|
||
|
|
Memory was exhausted.
|
||
|
|
.TP 19
|
||
|
|
.B ARES_EDESTRUCTION
|
||
|
|
The name service channel
|
||
|
|
.I channel
|
||
|
|
is being destroyed; the query will not be completed.
|
||
|
|
.PP
|
||
|
|
On successful completion of the query, the callback argument
|
||
|
|
.I hostent
|
||
|
|
points to a
|
||
|
|
.B struct hostent
|
||
|
|
containing the name of the host returned by the query. The callback
|
||
|
|
need not and should not attempt to free the memory pointed to by
|
||
|
|
.IR hostent ;
|
||
|
|
the ares library will free it when the callback returns. If the query
|
||
|
|
did not complete successfully,
|
||
|
|
.I hostent
|
||
|
|
will be
|
||
|
|
.BR NULL .
|
||
|
|
.SH SEE ALSO
|
||
|
|
.BR ares_process (3)
|
||
|
|
.SH AUTHOR
|
||
|
|
Greg Hudson, MIT Information Systems
|
||
|
|
.br
|
||
|
|
Copyright 1998 by the Massachusetts Institute of Technology.
|