#!/usr/bin/perl

# it is actually a 1-m tcp data distributor.

use warnings;
use strict;
use IO::Socket;

my $bidi;
my $loop;
my $myIp;
my $myPort;
my $ssl;
my $serverHost;
my $serverPort;
my $IPV6;
my $usage = "Usage: tcptee.pl [--IPV6] [--bidi] [--loop] [--ssl] " .
            "[myIp:]myPort[:serverHost:serverPort]\n";
sub tPrint($);

while(@ARGV) {
  my $opt = shift @ARGV;

  if($opt =~ m/^--bidi$/i) {
    $bidi = 1;

  } elsif($opt =~ m/^--IPV6$/i) {
    eval "require IO::Socket::INET6; use Socket6;";
    if($@) {
      tPrint $@;
      tPrint "Can't load INET6, falling back to IPV4";
    } else {
      $IPV6 = 1;
    }

  } elsif($opt =~ m/^--loop$/i) {
    $loop = 1

  } elsif($opt =~ m/^--ssl$/i) {
    $ssl = 1

  } elsif($opt =~ m/^(\d+)$/) {
    $myPort = $opt;

  } elsif($opt =~ m/^(.*):(\d+):(.*):(\d+)$/) {
    $myIp = $1;
    $myPort = $2;
    $serverHost = $3;
    $serverPort = $4;

  } elsif($opt =~ m/^(\d+):(.*):(\d+)$/) {
    $myPort = $1;
    $serverHost = $2;
    $serverPort = $3;

  } else {
    die $usage;

  }
}

my ($sfd, $myfd, %clients, $discoMsg);

die $usage if(!$myPort);

sub
tPrint($)
{
  my $arg = shift;
  my @t = localtime;
  printf("%04d.%02d.%02d %02d:%02d:%02d %s\n",
          $t[5]+1900,$t[4]+1,$t[3], $t[2],$t[1],$t[0], $arg);
}


for(;;) {

  # Open the server first
  if($serverHost) {
    $sfd = IO::Socket::INET->new(PeerAddr => "$serverHost:$serverPort");
    if(!$sfd) {
      tPrint "Cannot connect to $serverHost:$serverPort : $!" if(!$discoMsg);
      $discoMsg = 1;
      last if(!$loop);
      sleep(5);
      next;
    }
    $discoMsg = 1;
    tPrint "Connected to $serverHost:$serverPort";
  }


  # Now open our listener
  my @opts = (
    Domain    => $IPV6 ? AF_INET6() : AF_UNSPEC,
    LocalHost => $myIp,
    LocalPort => $myPort,
    Listen    => 10,
    ReuseAddr => 1
  );
  $myfd = $IPV6 ? 
          IO::Socket::INET6->new(@opts) :
          IO::Socket::INET->new(@opts);
  die "Opening port $myPort: $!\n" if(!$myfd);
  tPrint "Port $myPort opened";

  my $firstmsg; # HMLAN special

  # Data loop
  for(;;) {
    my ($rin,$rout) = ('','');
    vec($rin, $sfd->fileno(),  1) = 1 if($sfd);
    vec($rin, $myfd->fileno(), 1) = 1;
    foreach my $c (keys %clients) {
      vec($rin, fileno($clients{$c}{fd}), 1) = 1;
    }

    my $nfound = select($rout=$rin, undef, undef, undef);
    if($nfound < 0) {
      tPrint("select: $!");
      last;
    }

    # New connection
    if(vec($rout, $myfd->fileno(), 1)) {
      my @clientinfo = $myfd->accept();
      if(!@clientinfo) {
        tPrint "Accept failed: $!";
        next;
      }
      my ($port, $iaddr) = ($IPV6 ? sockaddr_in6($clientinfo[1]) :
                                    sockaddr_in($clientinfo[1]));
      my $fd = $clientinfo[0];
      $clients{$fd}{fd} = $fd;
      $clients{$fd}{addr} = ($IPV6 ? inet_ntop(AF_INET6(), $iaddr) :
                                     inet_ntoa($iaddr)) . ":$port";
      tPrint "Connection accepted from $clients{$fd}{addr}";

      if($ssl) {
        tPrint "Attaching SSL";
        eval "require IO::Socket::SSL";
        if($@) {
          tPrint "Can't load IO::Socket::SSL, falling back to plain";
        } else {
          my $ret = IO::Socket::SSL->start_SSL($fd, {
            SSL_server    => 1, 
            SSL_key_file  => "certs/server-key.pem",
            SSL_cert_file => "certs/server-cert.pem",
          });
          if(!$ret && $! ne "Socket is not connected") {
            die "SSL/HTTPS error: $!";
          }
        }
      }


      syswrite($fd, $firstmsg) if($firstmsg);
    }

    # Data from the server
    if($sfd && vec($rout, $sfd->fileno(), 1)) {
      my $buf;
      my $ret = sysread($sfd, $buf, 256);
      if(!defined($ret) || $ret <= 0) {
        tPrint "Short read from the server, disconnecting the clients.";
        last;
      }
      foreach my $c (keys %clients) {
        syswrite($clients{$c}{fd}, $buf);
        $clients{$c}{fd}->flush();
      }
      $firstmsg = $buf if(!$firstmsg);
    }

    # Data from one of the clients
CLIENT:foreach my $c (keys %clients) {
      next if(!vec($rout, fileno($clients{$c}{fd}), 1));
      for(;;) {
        my $buf;
        my $ret = sysread($clients{$c}{fd}, $buf, 256);
        if(!defined($ret) || $ret <= 0) {
          close($clients{$c}{fd});
          tPrint "Client $clients{$c}{addr} left us";
          delete($clients{$c});
          next CLIENT;
        }

        syswrite($sfd, $buf) if($sfd);
        if($bidi) {
          foreach my $c2 (keys %clients) {
            syswrite($clients{$c2}{fd}, $buf) if($c2 ne $c);
          }
        }
        last if(!$ssl || !$clients{$c}{fd}->pending());
      }
    }

  }

  close($sfd) if($sfd);
  close($myfd);
  foreach my $c (keys %clients) {
    close($clients{$c}{fd});
    delete($clients{$c});
  }
  last if(!$loop);
  sleep(1);
}