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# -*- mode: perl -*-
# ============================================================================
package Net::SNMP::Transport::IPv4::TCP;
# $Id: TCP.pm,v 3.0 2009/09/09 15:05:33 dtown Rel $
# Object that handles the TCP/IPv4 Transport Domain for the SNMP Engine.
# Copyright (c) 2004-2009 David M. Town <dtown@cpan.org>
# All rights reserved.
# This program is free software; you may redistribute it and/or modify it
# under the same terms as the Perl 5 programming language system itself.
# ============================================================================
use strict;
use Net::SNMP::Transport qw(
MSG_SIZE_MAXIMUM DOMAIN_TCPIPV4 TRUE FALSE DEBUG_INFO
);
use Net::SNMP::Message qw( SEQUENCE );
use IO::Socket qw( SOCK_STREAM );
## Version of the Net::SNMP::Transport::IPv4::TCP module
our $VERSION = v3.0.0;
## Handle importing/exporting of symbols
use base qw( Net::SNMP::Transport::IPv4 Net::SNMP::Transport );
sub import
{
return Net::SNMP::Transport->export_to_level(1, @_);
}
## RFC 3411 - snmpEngineMaxMessageSize::=INTEGER (484..2147483647)
sub MSG_SIZE_DEFAULT_TCP4 { 1460 } # Ethernet(1500) - IPv4(20) - TCP(20)
# [public methods] -----------------------------------------------------------
sub new
{
my ($this, $error) = shift->SUPER::_new(@_);
if (defined $this) {
if (!defined $this->_reasm_init()) {
return wantarray ? (undef, $this->error()) : undef;
}
}
return wantarray ? ($this, $error) : $this;
}
sub accept
{
my ($this) = @_;
$this->_error_clear();
my $socket = $this->{_socket}->accept();
if (!defined $socket) {
return $this->_perror('Failed to accept the connection');
}
DEBUG_INFO('opened %s socket [%d]', $this->type(), $socket->fileno());
# Create a new object by copying the current object.
my $new = bless { %{$this} }, ref $this;
# Now update the appropriate fields.
$new->{_socket} = $socket;
$new->{_dest_name} = $socket->peername();
$new->{_dest_hostname} = $new->sock_address();
if (!defined $new->_reasm_init()) {
return $this->_error($new->error());
}
# Return the new object.
return $new;
}
sub send
{
my $this = shift;
$this->_error_clear();
if (length($_[0]) > $this->{_max_msg_size}) {
return $this->_error(
'The message size %d exceeds the maxMsgSize %d',
length($_[0]), $this->{_max_msg_size}
);
}
if (!defined $this->{_socket}->connected()) {
return $this->_error(
q{Not connected to the remote host '%s'}, $this->dest_hostname()
);
}
my $bytes = $this->{_socket}->send($_[0], 0);
return defined($bytes) ? $bytes : $this->_perror('Send failure');
}
sub recv
{
my $this = shift;
$this->_error_clear();
if (!defined $this->{_socket}->connected()) {
$this->_reasm_reset();
return $this->_error(
q{Not connected to the remote host '%s'}, $this->dest_hostname()
);
}
# RCF 3430 Section 2.1 - "It is possible that the underlying TCP
# implementation delivers byte sequences that do not align with
# SNMP message boundaries. A receiving SNMP engine MUST therefore
# use the length field in the BER-encoded SNMP message to separate
# multiple requests sent over a single TCP connection (framing).
# An SNMP engine which looses framing (for example due to ASN.1
# parse errors) SHOULD close the TCP connection."
# If the reassembly bufer is empty then there is no partial message
# waiting for completion. We must then process the message length
# to properly determine how much data to receive.
my $name;
if ($this->{_reasm_buffer} eq q{}) {
if (!defined $this->{_reasm_object}) {
return $this->_error('The reassembly object is not defined');
}
# Read enough data to parse the ASN.1 type and length.
$name = $this->{_socket}->recv($this->{_reasm_buffer}, 6, 0);
if ((!defined $name) || ($!)) {
$this->_reasm_reset();
return $this->_perror('Receive failure');
} elsif (!length $this->{_reasm_buffer}) {
$this->_reasm_reset();
return $this->_error(
q{The connection was closed by the remote host '%s'},
$this->dest_hostname()
);
}
$this->{_reasm_object}->append($this->{_reasm_buffer});
$this->{_reasm_length} = $this->{_reasm_object}->process(SEQUENCE) || 0;
if ((!$this->{_reasm_length}) ||
($this->{_reasm_length} > MSG_SIZE_MAXIMUM))
{
$this->_reasm_reset();
return $this->_error(
q{Message framing was lost with the remote host '%s'},
$this->dest_hostname()
);
}
# Add in the bytes parsed to define the expected message length.
$this->{_reasm_length} += $this->{_reasm_object}->index();
}
# Setup a temporary buffer for the message and set the length
# based upon the contents of the reassembly buffer.
my $buf = q{};
my $buf_len = length $this->{_reasm_buffer};
# Read the rest of the message.
$name = $this->{_socket}->recv($buf, ($this->{_reasm_length} - $buf_len), 0);
if ((!defined $name) || ($!)) {
$this->_reasm_reset();
return $this->_perror('Receive failure');
} elsif (!length $buf) {
$this->_reasm_reset();
return $this->_error(
q{The connection was closed by the remote host '%s'},
$this->dest_hostname()
);
}
# Now see if we have the complete message. If it is not complete,
# success is returned with an empty buffer. The application must
# continue to call recv() until the message is reassembled.
$buf_len += length $buf;
$this->{_reasm_buffer} .= $buf;
if ($buf_len < $this->{_reasm_length}) {
DEBUG_INFO(
'message is incomplete (expect %u bytes, have %u bytes)',
$this->{_reasm_length}, $buf_len
);
$_[0] = q{};
return $name || $this->{_socket}->connected();
}
# Validate the maxMsgSize.
if ($buf_len > $this->{_max_msg_size}) {
$this->_reasm_reset();
return $this->_error(
'Incoming message size %d exceeded the maxMsgSize %d',
$buf_len, $this->{_max_msg_size}
);
}
# The message is complete, copy the buffer to the caller.
$_[0] = $this->{_reasm_buffer};
# Clear the reassembly buffer and length.
$this->_reasm_reset();
return $name || $this->{_socket}->connected();
}
sub connectionless
{
return FALSE;
}
sub domain
{
return DOMAIN_TCPIPV4; # transportDomainTcpIpv4
}
sub type
{
return 'TCP/IPv4'; # tcpIpv4(5)
}
sub agent_addr
{
return shift->sock_address();
}
# [private methods] ----------------------------------------------------------
sub _protocol_name
{
return 'tcp';
}
sub _protocol_type
{
return SOCK_STREAM;
}
sub _msg_size_default
{
return MSG_SIZE_DEFAULT_TCP4;
}
sub _reasm_init
{
my ($this) = @_;
my $error;
($this->{_reasm_object}, $error) = Net::SNMP::Message->new();
if (!defined $this->{_reasm_object}) {
return $this->_error(
'Failed to create the reassembly object: %s', $error
);
}
$this->_reasm_reset();
return TRUE;
}
sub _reasm_reset
{
my ($this) = @_;
if (defined $this->{_reasm_object}) {
$this->{_reasm_object}->error(undef);
$this->{_reasm_object}->clear();
}
$this->{_reasm_buffer} = q{};
$this->{_reasm_length} = 0;
return TRUE;
}
sub _tdomain
{
return DOMAIN_TCPIPV4; # transportDomainTcpIpv4
}
# ============================================================================
1; # [end Net::SNMP::Transport::IPv4::TCP]