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.\" $Id: ipproto.man,v 1.1 2000/06/01 03:19:06 jim Exp $
.\"
.Dd Jun 30, 2000
.Dt IPPROTO 3
.Os BIND9 9
.ds vT BIND9 Programmer's Manual
.Sh NAME
.Nm try_proto ,
.Nm initialize_action ,
.Nm isc_net_probeipv4 ,
.Nm isc_net_probeipv6
.Nd protocol probe functions
.Sh SYNOPSIS
.Fd #include  <config.h>
 
.Fd #include <errno.h>
.Fd #include <unistd.h>
 
.Fd #include <isc/net.h>
.Fd #include <isc/once.h>
.Fd #include <isc/string.h>
.Fd #include <isc/util.h> 

.Ft static isc_result_t
.Fn try_proto "int domain"
.Ft static void
.Fn initialize_action
.Ft isc_result_t
.Fn isc_net_probeipv4 void
.Ft isc_result_t
.Fn isc_net_probeipv4 void
.Sh DESCRIPTION
.Fn isc_net_probeipv4
and
.Fn isc_net_probeipv6
check that the operating system support the IPv4 and IPv6 protocols
respectively.
They call
.Fn try_proto
which tries to create a socket of type
.Dv SOCK_STREAM
for the appropriate protocol family,
.Fa domain .
.Pp
.Fn initialize_action
sets the external variables
.Dv ipv4_result
and
.Dv ipv6_result
to
.Er ISC_R_SUCCESS
if the IPv4 and IPv6 protocols respectively are supported by the
operating system.
These variables can be tested by applications which need to perform
protocol-specific tasks.
.Sh RETURN VALUES
.Fn isc_net_probeipv4
returns 
.Er ISC_R_SUCCESS
if the IPv4 protocol is supported by the kernel and
.Fn isc_net_probeipv6
returns
.Er ISC_R_SUCCESS 
if the operating system supports IPv6.
.Fn try_proto
returns
.Fn ISC_R_NOTFOUND
if the chosen protocol family
.Fa domain
is not supported by the kernel.
An error message is printed on
.Dv stderr
and
.Er ISC_R_UNEXPECTED
returned if another error occurred when the attempt was made to create
the
.Dv SOCK_STREAM
socket.
.Sh SEE ALSO
.Xr socket 2 ,
.Xr ip 4 ,
.Xr ipv6 4 .