From e30bd8928e466b1b7b33440352af079779bd0611 Mon Sep 17 00:00:00 2001
From: root <root@sysrq>
Date: Wed, 4 Apr 2007 14:32:57 +0200
Subject: [PATCH] Make survey functionality for MBD.

---
 mbd/mbd.pl    | 96 ++++++++++++++++++++++++++++++++++++++++++++++++---
 mbd/survey.pl | 10 ++++++
 2 files changed, 102 insertions(+), 4 deletions(-)
 create mode 100644 mbd/survey.pl

diff --git a/mbd/mbd.pl b/mbd/mbd.pl
index dcc25fe..4843b0b 100644
--- a/mbd/mbd.pl
+++ b/mbd/mbd.pl
@@ -7,6 +7,7 @@ use Net::RawIP;
 use Time::HiRes;
 require './access_list.pl';
 require './nets.pl';
+require './survey.pl';
 require './mbd.pm';
 
 sub fhbits {
@@ -20,6 +21,10 @@ sub fhbits {
 # used for rate limiting
 my %last_sent = ();
 
+# for own surveying
+my %active_surveys = ();
+my %last_survey = ();
+
 my %cidrcache = ();
 sub cache_cidrlookup {
 	my ($addr, $net) = @_;
@@ -44,7 +49,7 @@ sub cache_cidrrange {
 
 open LOG, ">>", "mbd.log";
 
-my @ports = mbd::find_all_ports();
+my @ports = ( mbd::find_all_ports() , $Config::survey_port_low, $Config::survey_port_high );
 
 # Open a socket for each port
 my @socks = ();
@@ -66,6 +71,21 @@ while (1) {
 	my $rout;
 
 	my $nfound = select($rout=$rin, undef, undef, undef);
+	my $now = [Time::HiRes::gettimeofday];
+
+	# First of all, close any surveys that are due.
+	for my $sport (keys %active_surveys) {
+		my $age = Time::HiRes::tv_interval($active_surveys{$sport}{start}, $now);
+		if ($age > $Config::survey_time && $active_surveys{$sport}{active}) {
+			print "Survey for port " . $active_surveys{$sport}{dport} . ": " .
+				$active_surveys{$sport}{num} . " active servers.\n";
+			$active_surveys{$sport}{active} = 0;
+		}
+		if ($age > $Config::survey_time * 3.0) {
+			delete $active_surveys{$sport};
+		}
+	}
+
 	for my $sock (@socks) {
 		next unless (vec($rout, fileno($sock), 1) == 1);
 
@@ -75,8 +95,23 @@ while (1) {
 		my ($dport, $daddr) = sockaddr_in(getsockname($sock));
 		my $size = length($data);
 
+		# Check if this is a survey reply
+		if ($dport >= $Config::survey_port_low && $dport <= $Config::survey_port_high) {
+			if (!exists($active_surveys{$dport})) {
+				print "WARNING: Unknown survey port $dport, ignoring\n";
+				next;
+			}
+			if (!$active_surveys{$dport}{active}) {
+				# remains
+				next;
+			}
+			
+			++$active_surveys{$dport}{num};
+
+			next;
+		}
+
 		# Rate limiting
-		my $now = [Time::HiRes::gettimeofday];
 		if (exists($last_sent{$saddr}{$dport})) {
 			my $elapsed = Time::HiRes::tv_interval($last_sent{$saddr}{$dport}, $now);
 			if ($elapsed < 1.0) {
@@ -110,8 +145,40 @@ while (1) {
 
 		$last_sent{$saddr}{$dport} = $now;
 
-		my $num_nets = 0;
+		# The packet is OK! Do we already have a recent enough survey
+		# for this port, or should we use this packet?
+		my $survey = 1;
+		if (exists($last_survey{$dport})) {
+			my $age = Time::HiRes::tv_interval($last_survey{$dport}, $now);
+			if ($age < $Config::survey_freq) {
+				$survey = 0;
+			}
+		}
+
+		# New survey; find an unused port
+		my $survey_sport;
+		for my $port ($Config::survey_port_low..$Config::survey_port_high) {
+			if (!exists($active_surveys{$port})) {
+				$survey_sport = $port;
+
+				$active_surveys{$port} = {
+					start => $now,
+					active => 1,
+					dport => $dport,
+					num => 0
+				};
+				$last_survey{$dport} = $now;
+
+				last;
+			}
+		}
+
+		if (!defined($survey_sport)) {
+			print "WARNING: no free survey source ports, not surveying.\n";
+			$survey = 0;
+		}
 
+		my $num_nets = 0;
 		for my $net (@Config::networks) {
 			next if (cache_cidrlookup(inet_ntoa($saddr), $net));
 
@@ -131,9 +198,30 @@ while (1) {
 				}
 			});
 			$sendsock->send;
+
+			if ($survey) {
+				$sendsock->set({
+					ip => {
+						saddr => $Config::survey_ip,
+						daddr => $broadcast
+					},
+					udp => {
+						source => $survey_sport,
+						dest => $dport,
+						data => $data
+					}
+				});
+				$sendsock->send;
+			}
+
 			++$num_nets;
 		}
-		print inet_ntoa($saddr), ", $dport, $size bytes => ($num_nets networks)\n";
+
+		if ($survey) {
+			print inet_ntoa($saddr), ", $dport, $size bytes => ($num_nets networks) [+survey from port $survey_sport]\n";
+		} else {
+			print inet_ntoa($saddr), ", $dport, $size bytes => ($num_nets networks)\n";
+		}
 	}
 }
 
diff --git a/mbd/survey.pl b/mbd/survey.pl
new file mode 100644
index 0000000..b73a279
--- /dev/null
+++ b/mbd/survey.pl
@@ -0,0 +1,10 @@
+package Config;
+
+our $survey_ip = "87.76.254.2";
+our $survey_port_low = 60000;
+our $survey_port_high = 60500;
+our $survey_freq = 60.0;
+our $survey_time = 3.0;
+
+1;
+
-- 
2.39.2