#!/bin/perl -w

use strict;
use IO::Socket;
use File::Basename;
use Getopt::Std qw(getopts);

my $PHRODO_PORT = 8009;
my $MAXLEN= 1024;
my $CONNECT_TIMEOUT = 10;
my $phonebook="phonebook";
my $phonebook_new="phonebook_new";
my $log="log";
my $date;
my $date2;

# usage stuff
use vars (
          q!$opt_d!, # debug mode
          );

my $prog = basename $0;
my $usage = "Usage: $prog [-d]\n";

getopts('d')
    or die $usage;
my $debug = $opt_d;
warn "Debug logging enabled\n" if $debug;

# server stuff
my $server;

$server = IO::Socket::INET->new( LocalPort => $PHRODO_PORT,
                                 Proto     => 'tcp',
                                 Type      => SOCK_STREAM,
                                 Listen    => SOMAXCONN,
                                 Reuse     => 1,
                                 );
unless( $server ) {
    die "socket could not be created: $@\n";
}

while (my $client = $server->accept()){
    $client->autoflush(1);
    
    $client->peeraddr();
    
    open (PHONEBOOK, "<$phonebook") or die "can't open $phonebook: $!"; 
    open (LOG, ">>$log") or die "can't open $log: $!"; 
    
    # Get hostname by name or by IP Address (whatever you prefer)
    # my $hostname = gethostbyaddr( $client->peeraddr(), AF_INET ) ;
    my $hostname = inet_ntoa($client->peeraddr());
    $date=localtime;
    print LOG "$date - Got connection from $hostname\n";
    
    # Get the message from the client
    my $newmsg;
    $client->recv($newmsg, $MAXLEN);
    $date=localtime;
    print LOG "$date - Recieved message from $hostname\n" if $debug;
    
    # If the message is a registration 
    if ($newmsg =~ /register/) {
	# Open phonebook_new filehandler
	open (PHONEBOOK_NEW, ">>$phonebook_new") or die "can't open $phonebook_new: $!"; 
	
	# Substitute the blank ip with the client address
	$newmsg =~ s/ip=0.0.0.0/ip=$hostname/g;
	$newmsg =~ s/\0//;
	
	# Store the register and host info as primary key in $unique_info
	(my $unique_info, my $other_info) = split /\|p/, $newmsg;
	(my $box_info, my $host_info) = split /\|/, $unique_info;
	
	# Parse the phonebook. If the unique info is there, client
	# already has entry. Check to see if the host has changed.
	# If it has changed, modify the entry for that box.
	# If the box is not found, add an entry to the phonebook.
	my $found=0;
	while(<PHONEBOOK>){
	    my $line = $_;
	    if ( $line =~ /^$box_info/ ){
		$found=1;
		
		# Update the registration time
		$date2=time();
		$line =~ s/rtime=\d.*\d\|udp_ip/rtime=$date2|udp_ip/;

		# Replace corresponding hostname with new one, if different
		if ($line !~ /ip=$hostname/ ){
		    # existing entry for box_id has diff hostname
		    $line =~ s/ip=\w.*\w\|p/ip=$hostname|p/;
		    $line =~ s/udp_ip=\w.*\w\|u/udp_ip=$hostname|u/;
		    $date=localtime;
		    print LOG "$date - Changed entry in phonebook for $box_info on $hostname\n" if $debug;
		}
	    }
	    print PHONEBOOK_NEW $line;
	}
	
	if (not $found) {
	    print PHONEBOOK_NEW "$newmsg\n";
	    $date=localtime;
	    print LOG "$date - Added $box_info to phonebook at $hostname\n" if $debug;
	}
	close (PHONEBOOK) or die "can't close $phonebook: $!";
	close (PHONEBOOK_NEW) or die "can't close $phonebook_new: $!";
	
	# Rename the phonebook with the modified entry
	rename($phonebook, "phonebook.orig") or system("rename", $phonebook, "phonebook.orig") or die "can't rename $phonebook to $phonebook.orig: $!";
	rename($phonebook_new, $phonebook) or system("rename", $phonebook_new, $phonebook) or die "can't rename $phonebook_new to $phonebook: $!";
	
	# Assign response variable to send to client. Must append 
	# null character.
	my $msg = "rtimer=600\0";
	$client->send($msg);

	$date=localtime;
	print LOG "$date - Sent message $msg to $hostname\n" if $debug;
    }
    
    # If the message is a query
    if ($newmsg =~ /query/){
	# Grab the box ID that the client is looking up
	(my $query, my $lookup) = split /\|/, $newmsg;
	(my $fieldlabel, my $box_id) = split /=/, $lookup;
	
	# Remove the null character
	$box_id =~ s/\0//;

	$date=localtime;
	print LOG "$date - $query looking for $box_id on $hostname\n" if $debug;
	
	# Parse phonebook. If the queried box ID is found, format a response.
	my $sendmsg = 0;
	while(<PHONEBOOK>){
	    my $line = $_;
	    if ( $line =~ /^register=$box_id\|ip/ ){
		$line =~ s/register=/serial=/g;
		$line =~ s/flags=[0-9]*\|/flags=1\|/g;
		$line =~ s/\|rtime/\|ctime=995591865\|utime=1016013554\|rtime/g;
		$sendmsg = "$line\0";
		$date=localtime;
		print LOG "$date - Query found $box_id in phonebook\n" if $debug;
	    }
	}
	if ($sendmsg){
	    # Send back response to client.
	    $client->send($sendmsg);
	}
	else {
	    # Send back unknown response to client
	    my $unknown = "UNKNOWN\0";
	    $client->send($unknown);
	    $date=localtime;
	    print LOG "$date - Query did not find $box_id in phonebook\n";
	}
	close (PHONEBOOK) or die "can't close $phonebook: $!";
    }
    $client->close();
    
    undef $client;
    
    close (LOG) or die "can't close $log: $!";

}
$server->close;