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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]