#!/usr/bin/perl

#Simples Server konstrukt by FlorianL;)

use strict;
require 5.002;
use warnings;
use IO::Socket;
use Carp;

my $cfgfile = "serverconfig.cfg";
my $keyfile = ".key.file";

my ($port, $username, $choosed, $coderef);
sub logmsg {print "$0 $$: @_ at ", scalar localtime, "\n" }
sub spawn;

sub genpass {
    print ("\nGenerating KeyFile\nEnter your Password: ");
    chomp (my $password = <STDIN>);
    my @chars = ("A" .. "Z");
    my $salt = join("", @chars[ map {rand @chars } (1 .. 2) ]);
    our $crypted = crypt("$password", "$salt");
    open(KEYFILE,">$keyfile") or die "Error: Cant write the Keyfile";
    print KEYFILE chomp($crypted);
    close (KEYFILE);
    print ("\nHash = $crypted\n");
    system("chmod 666 $keyfile");
    print ("Keyfile saved to $keyfile!\nPermissions set to 666\nUpload it to your Clients now!\n");
}

sub readconfig() {
    open(CONFIG,$cfgfile) or die "Error: Cant open $cfgfile";
    my @config=<CONFIG>;
    close(CONFIG);
    chomp($port = $config[0]);
    if ($port eq "") { die ("Error: No Port specified"); }
    chomp($username = $config[1]);
        if ($username eq "") { die ("Error: No Username specified"); }
}

sub writeconfig() {
    print ("Config\n------\n");
    print ("\nPort: ");
    my $port = <STDIN>;
    if ($port =~ m/[a-z]+/) { die ("Port must be a number!"); }
        print ("\nUsername: ");
    my $username = <STDIN>;
    print ("Config written to $cfgfile\n");
    my @config = ($port, $username,);
    open(CONFIG,">$cfgfile");
    print CONFIG (@config);
    close (CONFIG);
    if (-z "$keyfile") {
        print ("No KeyFile present, well we generate one now...\n");
        genpass();
    } else {
        print ("KeyFile allready present!\n");
    }
}

sub server() {
    readconfig();
    my $proto = getprotobyname('tcp');
    socket(SERVER, PF_INET, SOCK_STREAM, $proto)    || die "FAILED: socket: $!";
    setsockopt(SERVER, SOL_SOCKET, SO_REUSEADDR, pack ("l", 1))    || die "FAILED: setsockopt: $!";
    bind(SERVER, sockaddr_in($port, INADDR_ANY))    || die "FAILED: bind: $!";
    listen(SERVER, SOMAXCONN)    || die "FAILED: listen: $!";

    logmsg "Server started on Port $port";

    my $waitedpid = 0;
    my $paddr;

    sub KILLER {
            our $waitedpid = wait;
            $SIG{CHLD} = \&KILLER;
            logmsg "Killed $waitedpid" . ($? ? " with exit $?" : '');
    }
    $SIG{CHLD} = \&KILLER;
    for ($waitedpid = 0;
        ($paddr = accept(CLIENT,SERVER)) || $waitedpid;
        $waitedpid = 0, close CLIENT)
    {
        next if $waitedpid and not $paddr;
        my ($port,$iaddr) = sockaddr_in($paddr);
        my $name = gethostbyaddr($iaddr,AF_INET);

        logmsg "Connection from $name [",
            inet_ntoa($iaddr), "]
            at port $port";

    spawn sub {
        print "Hello there, $name\n";
        };
    }

    sub spawn {
        my $coderef = shift;
        unless (@_ == 0 && $coderef && ref($coderef) eq 'CODE' {
            confess "usage: spawn CODEREF";
        }
        my $pid;
        if (!defined($pid = fork)) {
            logmsg "cannot fork: $!";
            return;
        } elsif ($pid) {
            logmsg "begat $pid";
            return;
            }
        open (STDIN, "<&CLIENT")    || die "cant dup client to stdin";
        open (STDOUT, ">&CLIENT")    || die "cant dup client ti stdout";
        exit &$coderef();
        }
    }

sub help() {
    print ("Valid commandline Options are:\n");
    print ("-config        -Initiates Configuration\n");
    print ("-printcfg    -Print Config\n");
    print ("-server        -Starts the Server\n");
    print ("-genpass    -Generates a new keyfile (1st-timers: Use -config instead!\n");
}

main {
$choosed = $ARGV[0];
if ($choosed eq '-config') {
        writeconfig();
        exit 0;
} elsif ($choosed eq '-printcfg') {
        readconfig();
    print ("Port: $port");
    print ("Username: $username");
        exit 0;
} elsif ($choosed eq '-genpass') {
        genpass();
        exit 0;
} elsif ($choosed eq '-server') {
        server();
        exit 0;
} else {
    help();
        exit 0;
    }
}