=head1 NAME

AnyEvent::Socket - useful IPv4 and IPv6 stuff.

=head1 SYNOPSIS

   use AnyEvent::Socket;
   
   tcp_connect "gameserver.deliantra.net", 13327, sub {
      my ($fh) = @_
         or die "gameserver.deliantra.net connect failed: $!";
   
      # enjoy your filehandle
   };
   
   # a simple tcp server
   tcp_server undef, 8888, sub {
      my ($fh, $host, $port) = @_;
   
      syswrite $fh, "The internet is full, $host:$port. Go away!\015\012";
   };

=head1 DESCRIPTION

This module implements various utility functions for handling internet
protocol addresses and sockets, in an as transparent and simple way as
possible.

All functions documented without C<AnyEvent::Socket::> prefix are exported
by default.

=over 4

=cut

package AnyEvent::Socket;

no warnings;
use strict;

use Carp ();
use Errno ();
use Socket qw(AF_INET AF_UNIX SOCK_STREAM SOCK_DGRAM SOL_SOCKET SO_REUSEADDR);

use AnyEvent ();
use AnyEvent::Util qw(guard fh_nonblocking AF_INET6);
use AnyEvent::DNS ();

use base 'Exporter';

our @EXPORT = qw(
   parse_ipv4 parse_ipv6
   parse_ip parse_address
   format_ip format_address
   address_family
   inet_aton
   tcp_server
   tcp_connect
);

our $VERSION = 4.151;

=item $ipn = parse_ipv4 $dotted_quad

Tries to parse the given dotted quad IPv4 address and return it in
octet form (or undef when it isn't in a parsable format). Supports all
forms specified by POSIX (e.g. C<10.0.0.1>, C<10.1>, C<10.0x020304>,
C<0x12345678> or C<0377.0377.0377.0377>).

=cut

sub parse_ipv4($) {
   $_[0] =~ /^      (?: 0x[0-9a-fA-F]+ | 0[0-7]* | [1-9][0-9]* )
              (?:\. (?: 0x[0-9a-fA-F]+ | 0[0-7]* | [1-9][0-9]* ) ){0,3}$/x
      or return undef;

   @_ = map /^0/ ? oct : $_, split /\./, $_[0];

   # check leading parts against range
   return undef if grep $_ >= 256, @_[0 .. @_ - 2];

   # check trailing part against range
   return undef if $_[-1] >= 2 ** (8 * (4 - $#_));

   pack "N", (pop)
             + ($_[0] << 24)
             + ($_[1] << 16)
             + ($_[2] <<  8);
}

=item $ipn = parse_ipv6 $textual_ipv6_address

Tries to parse the given IPv6 address and return it in
octet form (or undef when it isn't in a parsable format).

Should support all forms specified by RFC 2373 (and additionally all IPv4
forms supported by parse_ipv4). Note that scope-id's are not supported
(and will not parse).

This function works similarly to C<inet_pton AF_INET6, ...>.