#!/usr/bin/perl

use strict;
use warnings;
use Net::SNMP ();
use Net::Netmask;
use Data::Dumper;
use Getopt::Long;
use List::Util;

sub usage {
	die <<AMEN ;
Usage: $0 [<options>] <ip-addr>

Options:
--debug		Show debugging outputs
--mac		Show one MAC address learned per port
--allmac	Show all MAC addresses learned per port
--force-v1	Use SNMPv1 (work-around for buggy switches)
AMEN
}

my $debug = 0;
my $mac = 0;
my $all_mac = 0;
my $force_v1 = 0;
GetOptions(
	'debug' => \$debug,
	'mac' => \$mac,
	'allmac' => \$all_mac,
	'force-v1' => \$force_v1,
) or usage;

@ARGV == 1 or usage;
my ($switch_ip) = @ARGV;
my $community = 'public';
$mac ||= $all_mac;

my $is_tty = -t STDOUT;
sub attr {
	my ($a) = @_;
	return $is_tty ? `tput $a` : "";
}
my $t_red = attr("setaf 1");
my $t_green = attr("setaf 2");
my $t_yellow = attr("setaf 3");
my $t_magenta = attr("setaf 5");
my $t_norm = attr("sgr0");

my ($snmp, $err) = Net::SNMP->session(
	-hostname => $switch_ip,
	-version => ($force_v1 ? '1' : '2c'),
	-community => $community,
);
$snmp or die "Cannot establish session: $err\n";
$snmp->translate(0);

sub my_get_table {
	my ($cols) = @_;
	my $tab = {};
	for my $c (keys %$cols) {
		my $depth = split /\./, $cols->{$c};
		my $t = $snmp->get_table(-baseoid => $cols->{$c}) or next;
		for my $k (keys %$t) {
			my @k = split /\./, $k;
			my $kk = join('.', @k[$depth..$#k]);
			$tab->{$kk}->{$c} = $t->{$k};
		}
	}
	return $tab;
}

sub format_uptime {
	my ($t) = @_;
	my $d = "";
	$t = int($t/100);
	if ($t >= 86400) {
		$d = int($t/86400) . " days, ";
		$t %= 86400;
	}
	return $d . sprintf "%02d:%02d:%02d", int($t/3600), int(($t%3600)/60), $t%60;
}

my $OID_basic = '1.3.6.1.2.1.1';

my $basics = my_get_table({
	'desc' => "$OID_basic.1",
	'uptime' => "$OID_basic.3",
	'contact' => "$OID_basic.4",
	'name' => "$OID_basic.5",
	'location' => "$OID_basic.6",
});
print Dumper($basics) if $debug;
my $bas = $basics->{0} or die "Cannot find basic info";

print "### Basics ###\n\n";
print "Device:   ", $bas->{desc}, "\n";
print "Uptime:   ", format_uptime($bas->{uptime}), "\n";
print "Contact:  ", $bas->{contact}, "\n";
print "Name:     ", $bas->{name}, "\n";
print "Location: ", $bas->{location}, "\n";

my $OID_ifTable = '1.3.6.1.2.1.2.2';
my $OID_ifTablev2 = '1.3.6.1.2.1.31.1.1';

my $if_table = my_get_table({
	'desc' => "$OID_ifTable.1.2",
	'speed' => "$OID_ifTable.1.5",
	'mac' => "$OID_ifTable.1.6",
	'admin' => "$OID_ifTable.1.7",
	'oper' => "$OID_ifTable.1.8",
	'name' => "$OID_ifTablev2.1.1",
	'hispeed' => "$OID_ifTablev2.1.15",
	'alias' => "$OID_ifTablev2.1.18",
});
my %if_macs = ();
for my $if (values %$if_table) {
	$if->{mac} = join(':', map { sprintf "%02x", ord $_ } split(//, $if->{mac}));
	$if_macs{$if->{mac}} = 1;
}
print Dumper($if_table) if $debug;
my @ifaces = sort { $a <=> $b } keys %$if_table;
print "MAC addr: ", join(" ", sort keys %if_macs), "\n";

my $OID_ipTable = '1.3.6.1.2.1.4.20';
my $ip_table = my_get_table({
	'iface' => "$OID_ipTable.1.2",
	'mask' => "$OID_ipTable.1.3",
});
print Dumper($ip_table) if $debug;

# XXX: IPv6 not supported yet
for my $ipa (keys %$ip_table) {
	my $ip = $ip_table->{$ipa};
	my $if = $if_table->{$ip->{iface}} or die "IP table refers to unknown iface";
	my $nm = Net::Netmask->new2($ipa, $ip->{mask}) or die "Cannot parse IP prefix";
	push @{$if->{ip_addrs}}, $ipa . '/' . $nm->bits;
}
print Dumper($if_table) if $debug;

if ($mac) {
	my $OID_1qTpFdbTable = '1.3.6.1.2.1.17.7.1.2.2';
	my $vlan_fdb_table = my_get_table({
		'port' => "$OID_1qTpFdbTable.1.2",
		'status' => "$OID_1qTpFdbTable.1.3",
	});
	print Dumper($vlan_fdb_table) if $debug;

	if (%$vlan_fdb_table) {
		for my $m (keys %$vlan_fdb_table) {
			my $fdb = $vlan_fdb_table->{$m};
			$fdb->{status} == 3 or next;	# Only learned MACs
			my $port = $if_table->{$fdb->{port}} or die "Forwarding DB refers to unknown iface";
			my @m = split /\./, $m;
			my $vlan = shift @m;
			my $mac = join(':', map { sprintf('%02x', $_) } @m);
			push @{$port->{macs}}, $mac;
		}
	} else {
		print "# Trying fall-fack to .1d FDB\n" if $debug;
		my $OID_1dTpFdbTable = '1.3.6.1.2.1.17.4.3';
		my $fdb_table = my_get_table({
			'port' => "$OID_1dTpFdbTable.1.2",
			'status' => "$OID_1dTpFdbTable.1.3",
		});
		print Dumper($fdb_table) if $debug;
		for my $m (keys %$fdb_table) {
			my $fdb = $fdb_table->{$m};
			$fdb->{status} == 3 or next;	# Only learned MACs
			my $port = $if_table->{$fdb->{port}} or die "Forwarding DB refers to unknown iface";
			my @m = split /\./, $m;
			my $mac = join(':', map { sprintf('%02x', $_) } @m);
			push @{$port->{macs}}, $mac;
		}
	}

	for my $if (values %$if_table) {
		$if->{macs} or next;
		$if->{macs} = [ sort(List::Util::uniq(@{$if->{macs}})) ];
	}
}

my $OID_VlanStaticTable = '1.3.6.1.2.1.17.7.1.4.3';
my $vlan_table = my_get_table({
	'name' => "$OID_VlanStaticTable.1.1",
	'egress-ports' => "$OID_VlanStaticTable.1.2",
	'untagged-ports' => "$OID_VlanStaticTable.1.4",
	'row-status' => "$OID_VlanStaticTable.1.5",
});
for my $vlan (values %$vlan_table) {
	for my $k ('egress-ports', 'untagged-ports') {
		$vlan->{$k} = [ split //, unpack("B*", $vlan->{$k} // "") ];
	}
}
print Dumper($vlan_table) if $debug;
my @vlans = sort { $a <=> $b } grep { $vlan_table->{$_}->{'row-status'} == 1 } keys %$vlan_table;

print "\n### VLANs ###\n\n";
if (@vlans) {
	for my $vid (@vlans) {
		printf "%-4d  %s\n", $vid, $vlan_table->{$vid}->{'name'} // '-';
	}
} else {
	print "No VLAN support.\n";
}

print "\n### Ports ###\n\n";
# XXX: We assume that 802.1d switch ports IDs are equal to interface IDs
for my $port (@ifaces) {
	my $if = $if_table->{$port};
	my $state;
	my $scolor = $t_norm;
	if ($if->{'admin'} != 1) {
		$state = 'OFF';
	} elsif ($if->{'oper'} != 1) {
		$state = 'DOWN';
		$scolor = $t_red;
	} else {
		$state = 'UP';
		$scolor = $t_green;
	}
	my $speed = $if->{hispeed} || int($if->{speed} / 1000000);
	if (!$speed) {
		$speed = "";
	} elsif ($speed < 1000) {
		$speed = "${speed}M";
	} else {
		$speed = int($speed/1000);
		$speed = "${speed}G";
	}
	printf "%-4d %-15.15s  %s%-4s %-5s %s%-20s%s", $port, $if->{name}, $scolor, $state, $speed, $t_yellow, $if->{alias}, $t_norm;

	if ($mac) {
		my $show_mac = "";
		my $more_macs = " ";
		my @macs = @{$if->{macs} // []};
		if (@macs) {
			$show_mac = $macs[0];
			$more_macs = "${t_yellow}+${t_norm}" if @macs > 1;
		}
		printf "%-17s%s ", $show_mac, $more_macs;
	}

	for my $vid (@vlans) {
		my $vlan = $vlan_table->{$vid};
		if ($vlan->{'egress-ports'}->[$port]) {
			if ($vlan->{'untagged-ports'}->[$port]) {
				if ($t_green ne "") {
					print " ${t_green}${vid}${t_norm}";
				} else {
					print " ${vid}U";
				}
			} else {
				print " $vid";
			}
		}
	}

	print "\n";

	if ($if->{ip_addrs}) {
		print "${t_yellow}     IP: ", join(" ", @{$if->{ip_addrs}}), "${t_norm}\n";
	}
	if ($all_mac) {
		if ($if->{mac}) {
			print "${t_yellow}     Local MAC: ", $if->{mac}, "${t_norm}\n";
		}
		if ($if->{macs}) {
			for my $m (@{$if->{macs}}) {
				print "${t_magenta}     MAC: $m${t_norm}\n";
			}
		}
	}
}