#!/usr/bin/perl

# remove entries from the .ssh/known_hosts file for a node

use strict;
use Getopt::Long;
use Data::Dumper;
#$Data::Dumper::Maxdepth=2;

# Globals - these are set once and then only read.
my $HELP;
my $VERBOSE;
my $file = '~/.ssh/known_hosts';

my $usage = sub {
   	my $exitcode = shift @_;
   	print "Usage: khrem <node>\n";
    print "       Removes the entries in the .ssh/known_hosts file associated with this node.\n";
	exit $exitcode;
};

# Process the cmd line args
Getopt::Long::Configure("bundling");
#Getopt::Long::Configure("pass_through");
Getopt::Long::Configure("no_pass_through");
if (!GetOptions('h|?|help'  => \$HELP, 'v|verbose' => \$VERBOSE)) { $usage->(1); }

if ($HELP) { $usage->(0); }
if (scalar(@ARGV)!=1) { $usage->(1); }
my $node = $ARGV[0];		# if they specified a hostname match, only show svrs that start with that

my @output = runcmd("host $node");
my $hostname;
my $line = shift @output;
#print "line=$line\n";
if ($line =~ m/is an alias for /) {
    ($hostname) = $line =~ m/is an alias for ([^\.]+)/;
    #print "hostname=$hostname\n";
    $line = shift @output;
  }
#print "line=$line\n";
my ($ip) = $line =~ m/has address (.+)$/;
if (defined($hostname)) {
    print "Removing entries from $file for: $node, $hostname, $ip\n";
    runcmd("sed -i '/^$node/d;/^$hostname/d;/^$ip/d' $file");
  }
else {
    print "Removing entries from $file for: $node, $ip\n";
    runcmd("sed -i '/^$node/d;/^$ip/d' $file");
}

exit(0);


# Pring msg only if -v was specified
sub verbose { if ($VERBOSE) { print shift, "\n"; } }




# Run a command.  If called in the context of return an array, it will capture the output
# of the cmd and return it.  Otherwise, it will display the output to stdout.
# If the cmd has a non-zero rc, this function will die with a msg.
sub runcmd
{
    my ($cmd) = @_;
    my $rc;

    $cmd .= ' 2>&1' ;
    verbose($cmd);

   	my @output;
   	if (wantarray) {
		@output = `$cmd`;
		$rc = $?;
	}
	else {
		system($cmd);
		$rc = $?;
	}

    if ($rc) {
        $rc = $rc >> 8;
        if ($rc > 0) { die "Error: rc $rc return from cmd: $cmd\n"; }
        else { die "Error: system error returned from cmd: $cmd\n"; }
    }
    elsif (wantarray) { return @output; }
}