snmp_session.pm

主要用于监控网络流量并动态产生可视化结果

sub index_compare ($$) {
  my ($i1, $i2) = @_;
  $i1 = '' unless defined $i1;
  $i2 = '' unless defined $i2;
  if ($i1 eq '') {
      return $i2 eq '' ? 0 : 1;
  } elsif ($i2 eq '') {
      return 1;
  } elsif (!$i1) {
      return $i2 eq '' ? 1 : !$i2 ? 0 : 1;
  } elsif (!$i2) {
      return -1;
  } else {
    my ($f1,$r1) = split('\.',$i1,2);
    my ($f2,$r2) = split('\.',$i2,2);

    if ($f1 < $f2) {
      return -1;
    } elsif ($f1 > $f2) {
      return 1;
    } else {
      return index_compare ($r1,$r2);
    }
  }
}

sub oid_diff ($$) {
  my($base, $full) = @_;
  my $base_dotnot = join ('.',@{$base});
  my $full_dotnot = BER::pretty_oid ($full);

  return undef unless substr ($full_dotnot, 0, length $base_dotnot)
    eq $base_dotnot
      && substr ($full_dotnot, length $base_dotnot, 1) eq '.';
  substr ($full_dotnot, length ($base_dotnot)+1);
}

sub pretty_address
{
    my($addr) = shift;
    my($port,$ipaddr) = unpack_sockaddr_in($addr);
    return sprintf ("[%s].%d",inet_ntoa($ipaddr),$port);
}

sub version { $VERSION; }

package SNMPv1_Session;

use strict qw(vars subs);	# see above
use vars qw(@ISA);
use SNMP_Session;
use Socket;
use BER;

@ISA = qw(SNMP_Session);

sub snmp_version { 0 }

sub open
{
    my($this,$remote_hostname,$community,$port,
       $max_pdu_len,$bind_to_port,$max_repetitions) = @_;
    my($name,$aliases,$remote_addr,$socket);

    my $udp_proto = 0;

    $community = 'public' unless defined $community;
    $port = SNMP_Session::standard_udp_port unless defined $port;
    $max_pdu_len = 8000 unless defined $max_pdu_len;
    $max_repetitions = $default_max_repetitions
	unless defined $max_repetitions;
    $remote_addr = inet_aton ($remote_hostname)
	|| return $this->error_return ("can't resolve \"$remote_hostname\" to IP address");
    $socket = 'SNMP'.sprintf ("%s:%d", inet_ntoa ($remote_addr), $port);
    (($name,$aliases,$udp_proto) = getprotobyname('udp'))
	unless $udp_proto;
    $udp_proto=17 unless $udp_proto;
    socket ($socket, PF_INET, SOCK_DGRAM, $udp_proto)
	|| return $this->error_return ("creating socket: $!");
    if (defined $bind_to_port) {
	my $sockaddr = sockaddr_in ($bind_to_port, INADDR_ANY);
	bind ($socket, $sockaddr)
	    || return $this->error_return ("binding to port $bind_to_port: $!");
    }
    $remote_addr = pack_sockaddr_in ($port, $remote_addr);
    bless {
	   'sock' => $socket,
	   'sockfileno' => fileno ($socket),
	   'community' => $community,
	   'remote_hostname' => $remote_hostname,
	   'remote_addr' => $remote_addr,
	   'max_pdu_len' => $max_pdu_len,
	   'pdu_buffer' => '\0' x $max_pdu_len,
	   'request_id' => int (rand 0x80000000 + rand 0xffff),
	   'timeout' => $default_timeout,
	   'retries' => $default_retries,
	   'backoff' => $default_backoff,
	   'debug' => $default_debug,
	   'error_status' => 0,
	   'error_index' => 0,
	   'default_max_repetitions' => $max_repetitions,
	  };
}

sub open_trap_session (@) {
    my ($this, $port) = @_;
    $port = 162 unless defined $port;
    return $this->open ("0.0.0.0", "", 161, undef, $port);
}

sub sock { $_[0]->{sock} }
sub sockfileno { $_[0]->{sockfileno} }
sub remote_addr { $_[0]->{remote_addr} }
sub pdu_buffer { $_[0]->{pdu_buffer} }
sub max_pdu_len { $_[0]->{max_pdu_len} }
sub default_max_repetitions { $_[0]->{default_max_repetitions} }

sub close
{
    my($this) = shift;
    close ($this->sock) || $this->error ("close: $!");
}

sub wrap_request
{
    my($this) = shift;
    my($request) = shift;

    encode_sequence (encode_int ($this->snmp_version),
		     encode_string ($this->{community}),
		     $request)
      || return $this->ber_error ("wrapping up request PDU");
}

my @error_status_code = qw(noError tooBig noSuchName badValue readOnly
			   genErr noAccess wrongType wrongLength
			   wrongEncoding wrongValue noCreation
			   inconsistentValue resourceUnavailable
			   commitFailed undoFailed authorizationError
			   notWritable inconsistentName);

sub unwrap_response_5b
{
    my ($this,$response,$tag,$oids,$errorp) = @_;
    my ($community,$request_id,@rest,$snmpver);

    ($snmpver,$community,$request_id,
     $this->{error_status},
     $this->{error_index},
     @rest)
	= decode_by_template ($response, "%{%i%s%*{%i%i%i%{%@",
			      $tag);
    return $this->ber_error ("Error decoding response PDU")
      unless defined $snmpver;
    return $this->error ("Received SNMP response with unknown snmp-version field $snmpver")
	unless $snmpver == $this->snmp_version;
    if ($this->{error_status} != 0) {
      if ($errorp) {
	my ($oid, $errmsg);
	$errmsg = $error_status_code[$this->{error_status}] || $this->{error_status};
	$oid = $oids->[$this->{error_index}-1]
	  if $this->{error_index} > 0 && $this->{error_index}-1 <= $#{$oids};
	$oid = $oid->[0]
	  if ref($oid) eq 'ARRAY';
	return ($community, $request_id,
		$this->error ("Received SNMP response with error code\n"
			      ."  error status: $errmsg\n"
			      ."  index ".$this->{error_index}
			      .(defined $oid
				? " (OID: ".&BER::pretty_oid($oid).")"
				: "")));
      } else {
	if ($this->{error_index} == 1) {
	  @rest[$this->{error_index}-1..$this->{error_index}] = ();
	}
      }
    }
    ($community, $request_id, @rest);
}

sub send_query ($$)
{
    my ($this,$query) = @_;
    send ($this->sock,$query,0,$this->remote_addr);
}

sub receive_response_3
{
    my ($this, $response_tag, $oids, $errorp) = @_;
    my ($remote_addr);
    $remote_addr = recv ($this->sock,$this->{'pdu_buffer'},$this->max_pdu_len,0);
    return $this->error ("receiving response PDU: $!")
	unless defined $remote_addr;
    return $this->error ("short (".length $this->{'pdu_buffer'}
			 ." bytes) response PDU")
	unless length $this->{'pdu_buffer'} > 2;
    my $response = $this->{'pdu_buffer'};
    ##
    ## Check whether the response came from the address we've sent the
    ## request to.  If this is not the case, we should probably ignore
    ## it, as it may relate to another request.
    ##
    if ($this->{'debug'} && $remote_addr ne $this->{'remote_addr'}) {
	warn "Response came from ".&SNMP_Session::pretty_address($remote_addr)
	    .", not ".&SNMP_Session::pretty_address($this->{'remote_addr'})
		unless $SNMP_Session::suppress_warnings;
    }
    $this->{'last_sender_addr'} = $remote_addr;
    my ($response_community, $response_id, @unwrapped)
	= $this->unwrap_response_5b ($response, $response_tag,
				     $oids, $errorp);
    if ($response_community ne $this->{community}
        || $response_id ne $this->{request_id}) {
	if ($this->{'debug'}) {
	    warn "$response_community != $this->{community}"
		unless $SNMP_Session::suppress_warnings
		    || $response_community eq $this->{community};
	    warn "$response_id != $this->{request_id}"
		unless $SNMP_Session::suppress_warnings
		    || $response_id == $this->{request_id};
	}
	return 0;
    }
    if (!defined $unwrapped[0]) {
	$this->{'unwrapped'} = undef;
	return undef;
    }
    $this->{'unwrapped'} = \@unwrapped;
    return length $this->pdu_buffer;
}

sub receive_trap
{
    my ($this) = @_;
    my ($remote_addr, $iaddr, $port, $trap);
    $remote_addr = recv ($this->sock,$this->{'pdu_buffer'},$this->max_pdu_len,0);
    return undef unless $remote_addr;
    ($port, $iaddr) = sockaddr_in($remote_addr);
    $trap = $this->{'pdu_buffer'};
    return ($trap, $iaddr, $port);
}

sub describe
{
    my($this) = shift;
    print $this->to_string (),"\n";
}

sub to_string
{
    my($this) = shift;
    my ($class,$prefix);

    $class = ref($this);
    $prefix = ' ' x (length ($class) + 2);
    ($class." (remote host: \"".$this->{remote_hostname}
     ."\" ".&SNMP_Session::pretty_address ($this->remote_addr)."\n"
     .$prefix."  community: \"".$this->{'community'}."\"\n"
     .$prefix." request ID: ".$this->{'request_id'}."\n"
     .$prefix."PDU bufsize: ".$this->{'max_pdu_len'}." bytes\n"
     .$prefix."    timeout: ".$this->{timeout}."s\n"
     .$prefix."    retries: ".$this->{retries}."\n"
     .$prefix."    backoff: ".$this->{backoff}.")");
##    sprintf ("SNMP_Session: %s (size %d timeout %g)",
##    &SNMP_Session::pretty_address ($this->remote_addr),$this->max_pdu_len,
##	       $this->timeout);
}

### SNMP Agent support
### contributed by Mike McCauley <[e-mail]>
###
sub receive_request
{
    my ($this) = @_;
    my ($remote_addr, $iaddr, $port, $request);

    $remote_addr = recv($this->sock, $this->{'pdu_buffer'}, 
			$this->{'max_pdu_len'}, 0);
    return undef unless $remote_addr;
    ($port, $iaddr) = sockaddr_in($remote_addr);
    $request = $this->{'pdu_buffer'};
    return ($request, $iaddr, $port);
}

sub decode_request
{
    my ($this, $request) = @_;
    my ($snmp_version, $community, $requestid, $errorstatus, $errorindex, $bindings);

    ($snmp_version, $community, $requestid, $errorstatus, $errorindex, $bindings)
	= decode_by_template ($request, "%{%i%s%*{%i%i%i%@", SNMP_Session::get_request);
    if (defined $snmp_version)
    {
	# Its a valid get_request
	return(SNMP_Session::get_request, $requestid, $bindings, $community);
    }

    ($snmp_version, $community, $requestid, $errorstatus, $errorindex, $bindings)
	= decode_by_template ($request, "%{%i%s%*{%i%i%i%@", SNMP_Session::getnext_request);
    if (defined $snmp_version)
    {
	# Its a valid getnext_request
	return(SNMP_Session::getnext_request, $requestid, $bindings, $community);
    }

    ($snmp_version, $community, $requestid, $errorstatus, $errorindex, $bindings)
	= decode_by_template ($request, "%{%i%s%*{%i%i%i%@", SNMP_Session::set_request);
    if (defined $snmp_version)
    {
	# Its a valid set_request
	return(SNMP_Session::set_request, $requestid, $bindings, $community);
    }

    # Something wrong with this packet
    # Decode failed
    return undef;
}

package SNMPv2c_Session;
use strict qw(vars subs);	# see above
use vars qw(@ISA);
use SNMP_Session;
use BER;

@ISA = qw(SNMPv1_Session);

sub snmp_version { 1 }

sub open
{
    my $session = SNMPv1_Session::open (@_);
    return bless $session;
}

sub map_table_start_end ($$$$$$) {
    my ($session, $columns, $mapfn, $start, $end, $max_repetitions) = @_;

    my @encoded_oids;
    my $call_counter = 0;
    my $base_index = $start;
    $max_repetitions = $session->default_max_repetitions
	unless defined $max_repetitions;

    do {
	foreach (@encoded_oids = @{$columns}) {
	    $_=encode_oid (@{$_},split '\.',$base_index)
		|| return $session->ber_error ("encoding OID $base_index");
	}
	if ($session->getbulk_request_response (0, $max_repetitions,
						@encoded_oids)) {
	    my $response = $session->pdu_buffer;
	    my ($bindings) = $session->decode_get_response ($response);
	    my $smallest_index = undef;
	    my @collected_values = ();

	    my @bases = @{$columns};
	    my $n_bindings = 0;
	    while ($bindings ne '') {
		my ($binding, $oid, $value);
		unless (defined $bases[0]) {
		    @bases = @{$columns};
		    (++$call_counter,
		     &$mapfn ($smallest_index, @collected_values))
			if defined $smallest_index;
		    $base_index = $smallest_index;
		    $smallest_index = undef;
		    @collected_values = ();
		}
		my $base = shift @bases;

		($binding, $bindings) = decode_sequence ($bindings);
		($oid, $value) = decode_by_template ($binding, "%O%@");

		my $out_index;

		++$n_bindings;
		$out_index = SNMP_Session::oid_diff ($base, $oid);
		my $cmp;
		if (!defined $smallest_index
		    || ($cmp = SNMP_Session::index_compare
			($out_index,$smallest_index)) == -1) {
		    $smallest_index = $out_index;
		    grep ($_=undef, @collected_values);
		    push @collected_values, $value;
		} elsif ($cmp == 1) {
		    push @collected_values, undef;
		} else {
		    push @collected_values, $value;
		}
	    }
	    @bases = @{$columns};
	    (++$call_counter,
	     &$mapfn ($smallest_index, @collected_values))
		if defined $smallest_index;
	    $base_index = $smallest_index;
	    $smallest_index = undef;
	    @collected_values = ();
	} else {
	    return undef;
	}
    }
    while (defined $base_index
	   && (!defined $end || index_compare ($base_index, $end) < 0));
    $call_counter;
}

1;