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package Net::EPP::Protocol;
use bytes;
use Carp;
use vars qw($THRESHOLD);
use strict;
=pod
=head1 NAME
Net::EPP::Protocol - Low-level functions useful for both EPP clients and
servers.
=head1 SYNOPSIS
#!/usr/bin/perl
use Net::EPP::Protocol;
use strict;
# send a frame down a socket:
Net::EPP::Protocol->send_frame($socket, $xml);
# get a frame from a socket:
my $xml = Net::EPP::Protocol->get_frame($socket);
=head1 DESCRIPTION
This module implements functions that are common to both EPP clients and
servers that implement the TCP/TLS transport of the L<Extensible Provisioning
Protocol (EPP)|https://www.rfc-editor.org/info/std69> as defined in
L<RFC 5734|https://www.rfc-editor.org/rfc/rfc5734.html>. The only user of this
module is L<Net::EPP::Client>, but it may be useful if you want to write an EPP
server.
=head1 VARIABLES
=head2 $Net::EPP::Protocol::THRESHOLD
At least one EPP server implementation sends an unframed plain text error
message when a client connects from an unauthorised address. As a result, when
the first four bytes of the message are unpacked, the client tries to read and
allocate a very large amount of memory.
If the apparent frame length received from a server exceeds the value of
C<$Net::EPP::Protocol::THRESHOLD>, the C<get_frame()> method will croak.
The default value is 1GB.
=cut
BEGIN {
our $THRESHOLD = 1000000000;
}
=pod
=head1 METHODS
my $xml = Net::EPP::Protocol->get_frame($socket);
This method reads a frame from the socket and returns a scalar containing the
XML. C<$socket> must be an L<IO::Handle> or one of its subclasses (ie
C<IO::Socket::*>).
If the transmission fails for whatever reason, this method will C<croak()>, so
be sure to enclose it in an C<eval()>.
=cut
sub get_frame {
my ($class, $fh) = @_;
my $hdr;
if (!defined($fh->read($hdr, 4))) {
croak("Got a bad frame length from peer - connection closed?");
} else {
my $length = (unpack('N', $hdr) - 4);
if ($length < 0) {
croak("Got a bad frame length from peer - connection closed?");
} elsif (0 == $length) {
croak('Frame length is zero');
} elsif ($length > $THRESHOLD) {
croak("Frame length is $length which exceeds $THRESHOLD");
} else {
my $xml = '';
my $buffer;
while (length($xml) < $length) {
$buffer = '';
$fh->read($buffer, ($length - length($xml)));
last if (length($buffer) == 0); # in case the socket has closed
$xml .= $buffer;
}
return $xml;
}
}
}
=pod
Net::EPP::Protocol->send_frame($socket, $xml);
This method prepares an RFC 5734 compliant EPP frame and transmits it to the
remote peer. C<$socket> must be an L<IO::Handle> or one of its subclasses
(ie C<IO::Socket::*>).
If the transmission fails for whatever reason, this method will C<croak()>, so
be sure to enclose it in an C<eval()>. Otherwise, it will return a true value.
=cut
sub send_frame {
my ($class, $fh, $xml) = @_;
$fh->print($class->prep_frame($xml));
$fh->flush;
return 1;
}
=pod
my $frame = Net::EPP::Protocol->prep_frame($xml);
This method returns the XML frame in "wire format" with the protocol header
prepended to it. The return value can be printed directly to an open socket, for
example:
print STDOUT Net::EPP::Protocol->prep_frame($frame->toString);
=cut
sub prep_frame {
my ($class, $xml) = @_;
return pack('N', length($xml) + 4) . $xml;
}
1;
=pod
=head1 COPYRIGHT
This module is (c) 2008 - 2023 CentralNic Ltd and 2024 Gavin Brown. This module
is free software; you can redistribute it and/or modify it under the same terms
as Perl itself.
=cut
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