#!/usr/bin/perl -w
#
# peek.pl - walk up the IP stack looking for problems.
#
# 6/7/06 bet

use strict;

# Definitions
my $localnet="127.0.0.1";       # Should get this from "hosts" file.
my $router = "192.168.0.1";      # Your DSL gateway here.
#
# Files we need.
my $resolv = "/etc/resolv.conf";        # To get the nameservers from.
my $hosts = "/etc/hosts";               # To get "localhost" from.
#
# Commands
my $short_ping = "ping -t1 -c1 -n ";
my $dig_cmd = "dig";
my $dig_options = "+short +tries=1 +time=2";
my $config_cmd = "ifconfig";
my $status_cmd = "netstat -rn";
#
# Hold found routes.
my  @net;
my $token; my $host;

#
# Subroutines
#
sub check_interface  {          # ( -d|-u , "message" )
        my $option = shift @_;
        my $message = shift @_;
        my $ifs=`
                $config_cmd $option |
                perl -lne '\$\\=" "; print \$1 if m/^([a-z]+[0-9])[:]/'
        `;
        my @ifs=split / /, $ifs;
        print scalar @ifs, $message;
        print "\t$_\n" foreach @ifs;
        return @ifs
}

sub ping_host {
        my $host = shift @_;
        `$short_ping $host`;
        print '', ($?==0)?'working.':'***FAILED***', "\n";
}

# Abnomal exit point.  Used for network errors. Use "die" for program errors.
sub bail {      # Tell the user we can't continue.
        print shift @_;
        print "\nCan't continue tests.\n";
        exit 1;
}

#
# main - program starts here
#
`uname` =~ /FreeBSD/ or die "Program is for FreeBSD";

# Find any interfaces marked "down"
check_interface( "-d", " interfaces down:\n" );

# Find any interfaces marked "up"
my @ifs = check_interface( "-u", " interfaces up:\n" );

# Check localhost direct
printf "%-26s%-15s", "Checking localnet:", $localnet;
ping_host ( $localnet );

# Check local host via lookup
printf "%-41s", 'Checking "localhost" ';
ping_host( "localhost" );

# Find address of remaining interfaces.
# Check it
my $count=0;
foreach my $ifs (@ifs) {
        do {
                @net = grep m/inet /,  split /\n/, `$config_cmd $ifs`;
                if ( scalar @net != 1 ) {
                        print "$ifs: No inet record found.\n"; next };
                if ($net[0] =~ m/([0-9]+[.][0-9]+[.][0-9]+[.][0-9]+)/) {
                        printf "%-26s%-15s",
                                "Checking interface $ifs:", $1;
                        `$short_ping $1`;
                        if ($?==0) {
                                $count++;
                                print "working.\n";
                        } else {
                                print "***FAILED***\n";
                        }
                }
        } unless ( $ifs eq "lo0" );
}

if($count == 0) { bail  "No external interfaces!!!" };
print "$count external interface", ($count==1)?'':'s', " found.\n";

# Find default route and check
@net = grep m/default/,  split  '\n', `$status_cmd`;
if ( scalar @net == 0 ) { bail "No default route!" };
if ( scalar @net >= 2 ) { bail "Multiple default routes!" };
# Could be on different subnets??
($token, $host) = split ' ', $net[0];           #awk compatible pattern.
printf "%-26s%-15s", "Checking Default route:", $host;
ping_host ( $host );

# Ping router
printf "%-26s%-15s",  "Checking default router:", $router;
ping_host ( $router );

#       Could we maybe use TTL to resolve next hop? So we don't hardcode it.
#               Otherwice we have to get it from the router.
#               "ping -m3  $DNS" works, but would break if ??.

#       lookup DNS in /etc/resolv.conf
#               Check DNS
#
-e $resolv or die "Resolv.conf file ***missing ***";
open FH, $resolv or die "Open $resolv failed: $!";
while (<FH>) {
        next if ( length $_ < 10 );
        ($token, $host) = split ' ';            #awk compatible pattern.
        if ( $token eq "nameserver" ) {
                printf "%-26s", "Checking DNS host:";
                `$dig_cmd \@$host -x $host $dig_options` =~ m/([\w]|[.])+/;
                if ($?==0 ) {
                        print "$& working.\n";
                } else {
                        print "$host ***FAILED***!\n";
                }
        }
}
close FH;
# Normal program termination.
exit 0;
__END__