#!/usr/bin/perl

# VDR SVDRP Peer Demo
#
# This script broadcasts an SVDRP discover datagram on the SVDRP UDP port and
# then listens for replies  from peer VDRs on both the UDP and TCP port.
# It reacts properly to the SVDRP commands CONN, LSTT, POLL, PING and QUIT,
# and thus seems like a regular VDR to other VDRs.
#
# (C) 2018 by Klaus Schmidinger <Klaus.Schmidinger@tvdr.de>

use Getopt::Std;
use IO::Socket;
use IO::Select;

$DefaultSvdrpPort = 6419;
$DefaultSvdrpName = "peerdemo";

$Usage = qq{
Usage: $0 options

Options: -n name  use the given VDR name (default: $DefaultSvdrpName)
         -p port  use the given TCP port (default: $DefaultSvdrpPort)
         -v       be verbose
};

die $Usage if (!getopts("n:p:v"));

$Name    = $opt_n || $DefaultSvdrpName;
$Port    = $opt_p || $DefaultSvdrpPort;
$Verbose = $opt_v || 0;

# Open TCP and UDP sockets:

$TcpPort = $Port;
$UdpPort = $DefaultSvdrpPort;

$TcpSocket = new IO::Socket::INET(Listen => 5, LocalPort => $TcpPort, Proto => "tcp", ReusePort => 1) || die "$!";
$UdpSocket = new IO::Socket::INET(             LocalPort => $UdpPort, Proto => "udp", ReusePort => 1) || die "$!";
$SvdrpSelect = new IO::Select($TcpSocket);
setsockopt($UdpSocket, SOL_SOCKET, SO_RCVTIMEO, pack('L!L!', 0, 1000)); # 1ms timeout on UDP socket

# Send UDP broadcast:

$BcastSocket = new IO::Socket::INET(PeerAddr => '255.255.255.255', PeerPort => $UdpPort, Proto => "udp", Broadcast => 1) || die "$!";
$BcastMsg = "SVDRP:discover name:$Name port:$TcpPort vdrversion:20309 apiversion:20309 timeout:300";
Log('>', $BcastSocket, $BcastMsg);
print($BcastSocket $BcastMsg);
$BcastSocket->close();

# Listen on UDP and TCP socket:

while (1) {
      if ($UdpSocket->recv($Request, 1024)) {
         if (Extract($Request, "name") ne $Name) {
            Log('<', $UdpSocket, $Request);
            ReportVDR($Request, $UdpSocket->peerhost());
            }
         }
      if (my @Ready = $SvdrpSelect->can_read(0.01)) {
         for my $fh (@Ready) {
             if ($fh == $TcpSocket) {
                # accept connection:
                my $new = $TcpSocket->accept();
                Log('<', $new, "incoming TCP connection");
                # send mandatory response to simulate an SVDRP host:
                my $Prompt = "220 $Name SVDRP VideoDiskRecorder 2.3.9; Wed Nov 29 17:00:29 2017; ISO-8859-1";
                Log('>', $new, $Prompt);
                print($new "$Prompt\n");
                # add incoming connection to select:
                $SvdrpSelect->add($new);
                }
             else {
                # process connection:
                my $Request = "";
                $fh->recv($Request, 1024);
                chomp($Request);
                Log('<', $fh, $Request);
                if ($Request =~ /^CONN/) {
                   Reply($fh, "250 OK");
                   ReportVDR($Request, $fh->peerhost());
                   }
                elsif ($Request =~ /^LSTT/) {
                   Reply($fh, "550 No timers defined");
                   }
                elsif ($Request =~ /^POLL/) {
                   Reply($fh, "250 OK");
                   }
                elsif ($Request =~ /^PING/) {
                   Reply($fh, "250 $Name is alive");
                   }
                elsif ($Request =~ /^QUIT/) {
                   # close connection:
                   $SvdrpSelect->remove($fh);
                   $fh->close;
                   }
                }
             }
         }
      }

# Tools:

sub Reply
{
  my ($fh, $s) = @_;
  Log('>', $fh, $s);
  print($fh "$s\n");
}

sub ReportVDR
{
  my $s = shift;
  my $PeerHost = shift;
  $s .= " "; # for easier parsing
  my $Name       = Extract($s, "name");
  my $Port       = Extract($s, "port");
  my $VdrVersion = Extract($s, "vdrversion");
  my $ApiVersion = Extract($s, "apiversion");
  my $Timeout    = Extract($s, "timeout");
  print("found VDR '$Name' at $PeerHost with SVDRP port '$Port'\n");
}

sub Extract
{
  my ($s, $n) = @_;
  return ($s =~ / $n:([^ ]*) /)[0];
}

sub Log
{
  return unless ($Verbose);
  my ($Dir, $Socket, $Msg) = @_;
  printf("SVDRP %s [%s:%s] %s\n", $Dir, $Socket->peerhost(), $Socket->peerport(), $Msg);
}