AMPR-Rip44

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bin/rip44d  view on Meta::CPAN

{
	my($rkey) = @_;
	
	# This is ugly and slow - we fork /sbin/ip twice for every route change.
	# Should talk to the netlink device instead, but this is easier to
	# do right now, and good enough for this little routing table.
	my($out, $cmd);
	$cmd = "LANG=C $routebin route del $rkey";
	$out = `$cmd 2>&1`;
	if ($?) {
		if ($verbose > 1 || $out !~ /No such process/) {
			warn "route del failed: '$cmd': $out\n";
		}
	}
}

# expire old routes

sub expire_routes()
{
	warn "expiring old routes\n" if ($verbose);

bin/rip44d  view on Meta::CPAN

	# now go and update the routing table
	route_delete($rkey);
	my($out, $cmd);
	$cmd = "LANG=C $routebin route add $rkey via $nexthop dev $tunnel_if window $tcp_window onlink";
	$out = `$cmd 2>&1\n`;
	if ($?) {
		warn "route add failed: '$cmd': $out\n";
	}
}

# process a RIPv2 password authentication entry

sub process_rip_auth_entry($)
{
	my($entry) = @_;
	
	my $e_af = unpack('n', substr($entry, 0, 2));
	if ($e_af != 0xFFFF) {
		warn "RIPv2 first message does not contain auth password: ignoring\n" if ($verbose);
		return 0;
	}
	
	my $e_type = unpack('n', substr($entry, 2, 2));

bin/rip44d  view on Meta::CPAN

	
	# nexthop address does not point to self
	if (defined $my_addresses{$e_nexthop_s}) {
		warn "$e_net_s/$e_netmask_s => $e_nexthop_s blocked, local gw\n" if ($verbose);
		return (0, 'local gw');
	}
	
	return (1, 'ok');
}

# process a RIPv2 route entry

sub process_rip_route_entry($)
{
	my($entry) = @_;
	
	my $e_af = unpack('n', substr($entry, 0, 2));
	my $e_rtag = unpack('n', substr($entry, 2, 2));

	if ($e_af == 0xFFFF) {
		process_rip_auth_entry($entry);
		return -1;
	}
	
	if ($e_af != AF_INET) {
		warn "$me: RIPv2 entry has unsupported AF $e_af\n";
		return 0;
	}
	
	my $e_net = substr($entry, 4, 4);
	my $e_net_i = unpack('N', $e_net);

bin/rip44d  view on Meta::CPAN

	}
	
	warn "entry: af $e_af rtag $e_rtag $e_net_s/$e_netmask_s via $e_nexthop_s metric $e_metric\n" if ($verbose > 1);
	
	# Ok, we have a valid route, consider adding it in the kernel's routing table
	consider_route($e_net_s, $e_netmask_s, $e_nexthop_s, $e_rtag);
	
	return 1;
}

# process a RIP message

sub process_msg($$$)
{
	my($addr_s, $perr_port, $msg) = @_;
	
	# validate packet's length
	if (length($msg) < RIP_HDR_LEN + RIP_ENTRY_LEN) {
		warn "$me: ignored too short packet from $addr_s: " . length($msg) . "\n";
		return -1;
	}
	
	if (length($msg) > RIP_HDR_LEN + RIP_ENTRY_LEN*25) {

bin/rip44d  view on Meta::CPAN

	}
	if ($zero1 != 0 || $zero2 != 0) {
		warn "$me: ignored RIP packet from $addr_s: zero bytes are not zero in header\n";
		return -1;
	}
	
	my $init_msg = 0;
	
	# if password auth is required, require it!
	if (defined $rip_passwd) {
		return -1 if (!process_rip_auth_entry(substr($entries, 0, RIP_ENTRY_LEN)));
		$init_msg += RIP_ENTRY_LEN;
	}
	
	# Ok, process the actual route entries
	my $routes = 0;
	for (my $i = $init_msg; $i < length($entries); $i += RIP_ENTRY_LEN) {
		my $entry = substr($entries, $i, RIP_ENTRY_LEN);
		my $n = process_rip_route_entry($entry);
		return -1 if ($n < 0);
		$routes += $n;
	}
	
	return $routes;
}

#
####### main #############################################
#

bin/rip44d  view on Meta::CPAN

	LocalPort => 520,
	ReuseAddr => 1,
) or die $!;

$socket->mcast_add('224.0.0.9', $tunnel_if) or die $!;

my $expire_interval = 60*60;
my $next_expire = time() + $expire_interval;

# Main loop: receive broadcasts, check that they're from the correct
# address and port, and pass them on to processing
warn "entering main loop, waiting for RIPv2 datagrams\n" if ($verbose);
while (1) {
	my $msg;
	my $remote_address = recv($socket, $msg, 1500, 0);
	
	if (!defined $remote_address) {
		next;
	}
	
	my ($peer_port, $peer_addr) = unpack_sockaddr_in($remote_address);
	my $addr_s = inet_ntoa($peer_addr);
	
	if ($addr_s ne '44.0.0.1' || $peer_port ne 520) {
		warn "$me: ignored packet from $addr_s: $peer_port: " . length($msg) . "\n";
		next;
	}
	
	warn "received from $addr_s: $peer_port: " . length($msg) . " bytes\n" if ($verbose);
	
	my $routes = process_msg($addr_s, $peer_port, $msg);
	warn "processed $routes route entries\n" if ($verbose && $routes >= 0);
	
	# Consider expiring old routes. This is actually never run if we do not receive
	# any RIP broadcasts at all (the recv() is blocking)
	# The (desired) side effect is that if the RIP announcer
	# dies, the entries do not time out.
	if (time() > $next_expire || $next_expire > time() + $expire_interval) {
		$next_expire = time() + $expire_interval;
		expire_routes();
	}
}