#!/usr/bin/perl -W
#
# Maximilian Wilhelm <max@rfc2324.org>
#  --  Tue 04 Apr 2017 07:00:50 PM CEST
#

use strict;

# Should we check the OSPF process for IPv4 or IPv6?
my $cmds = {
	"-4" => "birdc",
	"-6" => "birdc6",
};

# Default to Legacy IP
my $cmd = $cmds->{"-4"};

if ($ARGV[0]) {
	unless (defined $cmds->{$ARGV[0]}) {
		print STDERR "Usage: $0 [ -4 | -6 ]\n";
		exit (1);
	}

	$cmd = $cmds->{$ARGV[0]};
}

my $code = 0;
my $msg = "";

if (not open (INTERFACES, "$cmd show ospf interface |")) {
	print "Failed to read OSPFv4 interfaces: $!\n";
	exit (2);
}

if (not open (NEIGHBORS, "$cmd show ospf neighbors |")) {
	print "Failed to read OSPFv4 neighbors: $!\n";
	exit (2);
}

# Store any configured OSPF interfaces
my $interfaces = {};
my $interface = undef;
while (my $line = <INTERFACES>) {
	chomp ($line);

	# Create entry in interface hash
	if ($line =~ /^Interface (.+) \(/) {
		$interface = $1;
		$interfaces->{$interface} = {};
	}
	
	# Store Type and State attributes
	elsif ($line =~ m/(Type|State): (.+)$/) {
		$interfaces->{$interface}->{$1} = $2;
	}
}

close (INTERFACES);


# Delete any stub interfaces from our list
for my $iface (keys %{$interfaces}) {
	if ($interfaces->{$iface}->{State} =~ m/\(stub\)/) {
		delete $interfaces->{$iface};
	}
}


my @ok = ();
my @broken = ();
my @down = ();

# Check all neighor states
while (my $line = <NEIGHBORS>) {
	chomp ($line);

	if ($line =~ m@^([[:xdigit:].:]+)\s+(\d+)\s+([[:alnum:]/-]+)\s+([0-9:]+)\s+([[:alnum:]_.-]+)\s+([[:xdigit:].:]+)@) {
		my ($peer, $state, $ifname) = ($1, $3, $5);
		my $interface = $interfaces->{$ifname};

		# Mark interfaces as "up" in bird
		$interface->{up} = 1;

		# State FULL is awesome.
		if ($state =~ m@Full@) {
			push @ok, "$ifname/$peer";
		}

		# In broadcast areas there are only two FULL sessions (to the DR and BDR),
		# all other sessions will be 2-Way/Other which is perfectly fine.
		elsif ($state eq "2-Way/Other" and $interface->{Type} eq "broadcast") {
			push @ok, "$ifname/$peer";
		}

		# Everything else is considered broken.
		# Likely some ExStart/* etc. pointing to possible MTU troubles.
		else {
			push @broken, "$ifname/$peer:$state";
		}
	}
}

close (NEIGHBORS);


# Check for any interfaces which should have (at least) an OSPF peer
# but don't appear in the neighbors list
for my $iface (keys %{$interfaces}) {
	if (not defined $interfaces->{$iface}->{up}) {
		push @down, $iface;
	}
}


# Any down interfaces?
if (@down) {
	$code = 2;
	$msg .= "DOWN: " . join (', ', @down) . " ";
}

# Any broken sessions?
if (@broken) {
	# Issue a warning when there are issues..
	if ($code < 2) {
		$code = 1
	}
	$msg .= "BROKEN: " . join (', ', @broken) . " ";
}

print $msg . "OK: " . join (', ', @ok) . "\n";
exit ($code);