#!/usr/bin/perl -wT

# CGI for stream exchange
#
# Author: Ulli Horlacher <framstag@rus.uni-stuttgart.de>

use Fcntl 	qw':flock :seek :mode';
use POSIX	qw'mkfifo';
use Digest::MD5 qw'md5_hex';

# add fex lib
(our $FEXLIB) = $ENV{FEXLIB} =~ /(.+)/;
die "$0: no $FEXLIB\n" unless -d $FEXLIB;

$| = 1;

# import from fex.pp
our ($tmpdir,@logdir,$timeout,$fra,$bs);

# load common code, local config: $HOME/lib/fex.ph
require "$FEXLIB/fex.pp" or die "$0: cannot load $FEXLIB/fex.pp - $!\n";

chdir $spooldir or error(500,"$spooldir - $!");

# my $debuglog = "$tmpdir/sex.log";
my $ra = $ENV{REMOTE_ADDR}||0;
$fra .= '/'.$ENV{HTTP_X_FORWARDED_FOR} if $ENV{HTTP_X_FORWARDED_FOR};
$timeout *= 10;

# normal / public :
# in normal mode the recipient needs authentification, not the sender
# in public mode the sender needs authentification, not the recipient

$user = $id = $pmode = $type = '';
$stream = 'STDSTR';
$mode = $ENV{REQUEST_METHOD} eq 'POST' ? 'PUSH' : 'POP';

# parse HTTP QUERY_STRING
if (my $qs = $ENV{QUERY_STRING}) {
  $qs = decode_b64($qs) if $qs =~ /^\w+=*$/;
  foreach (split '&',$qs) { setparam(split '=',"$_=") };
}

unless ($user) { error(400,"Missing user") }
if ($mdomain and $user !~ /@/) { $user .= '@'.$mdomain }
if ($user =~ /^anonymous/) {
  if (@anonymous_upload and ipin($ra,@anonymous_upload)) {
    mkdirp($user);
  } else {
    error(403,"Forbidden");
  }
} else {
  unless (-f "$user/@") { error(404,"Unknown user $user") }
}
chdir $user or error(500,"$user - $!");

$stream = "STREAM/$stream";

if ($mode eq 'PUSH') {
  if ($pmode eq 'PUBLIC') {
    &authentificate;
    $stream =~ s:/STDSTR:/PUBLIC:;
  }
  mkdirp($stream);
  my $fifo = "$stream/fifo";
  unless (-p $fifo) {
    mkfifo($fifo,0600) or error(503,"Cannot create $fifo : $!");
  }

  sexlog($mode);

  my $lock = "$stream/lock";
  open $lock,'>>',$lock or error(503,"Cannot open $lock : $!");
  flock $lock,LOCK_EX|LOCK_NB or error(409,"$stream already in use");

  chmod 0600,$fifo;
  unlink "$stream/mode";
  unlink "$stream/type";
  symlink $pmode,"$stream/mode" if $pmode;
  symlink $type, "$stream/type" if $type;

  $SIG{PIPE} = sub {
    sleep 1;
    rmrf($stream);
    exit;
  };
  $SIG{ALRM} = sub {
    syswrite STDOUT,".";
    exit if $!;
    $ALARM = 1;
  };
  syswrite STDOUT,"HTTP/1.9 199 Hold on";
  for (my $i=0;$i<$timeout;$i++) {
    alarm(1);
    $ALARM = 0;
    # will hang until $stream is opend for reading by another process
    open $fifo,'>',$fifo and last;
    unless ($ALARM) { error(503,"Cannot open $fifo : $!") }
  }
  alarm(0);
  syswrite STDOUT,"\r\n";

  unless (fileno $fifo) {
    rmrf($stream);
    error(504,"Timeout");
  }

  header('200 OK');

  $B = 0;
  $shutdown = sub { sexlog($B); rmrf($stream); exit; };
  $SIG{PIPE} = sub { sleep 1; &$shutdown; };
  # syswrite $fifo,$data if $data;
  while ($b = sysread(STDIN,$_,$bs)) {
    $B += $b;
    syswrite $fifo,$_ or die $!;
  }

  &$shutdown;
}
elsif ($mode eq 'POP') {
  $stream =~ s:/STDSTR:/PUBLIC: if $id eq 'public';
  unless ($id eq 'public' and (readlink "$stream/mode"||'') eq 'PUBLIC'
          or $user =~ /^anonymous/) {
    &authentificate;
  }
  error(503,"No $stream for $user") unless -d $stream;
  $type = readlink "$stream/type" || '';
  $SIG{ALRM} = sub { error(504,"Timeout") };
  alarm($timeout);
  my $fifo = "$stream/fifo";
  if (-e $fifo and not -r $fifo) { error(503,"$stream already in use") }
  open $fifo,'<',$fifo or error(503,"Cannot open $fifo : $!");
  chmod 0,$fifo;
  alarm(0);
  header('200 OK',$type);
  sexlog($mode);

  while (sysread($fifo,$_,$bs)) {
    syswrite STDOUT,$_ or die $!;
  }
  unlink $fifo;
  exit;

}
else {
  error(405,"Unknown Request");
}

exit;


sub setparam {
  my ($v,$vv) = @_;

  $v = uc(despace($v));
  $vv = untaint(normalize($vv));
  # $param{$v} = $vv;
  if    ($v eq 'USER') { $user	= lc(despace($vv)) }
  elsif ($v eq 'ID') { $id = despace($vv) }
  elsif ($v eq 'MODE') { $pmode = uc(despace($vv)) }
  elsif ($v eq 'TYPE') { $type = uc(despace($vv)) }
  elsif ($v eq 'STREAM') { $stream = normalize_filename($vv) }
  elsif ($v eq 'BS' and $vv =~ /(\d+)/) { $bs = $1 }
  elsif ($v eq 'TIMEOUT' and $vv =~ /(\d+)/) { $timeout	= $1 }
  elsif ($v eq 'ANONYMOUS') { $id = $user ='anonymous'; $stream = $vv; }
}

sub sexlog {
  my $msg = "@_";

  $msg =~ s/\n/ /g;
  $msg =~ s/\s+$//;
  $msg = sprintf "%s [%s_%s] %s (%s) %s\n",
                  isodate(time),$$,$ENV{REQUESTCOUNT},$user,$fra,$msg;

  foreach my $log (@logdir) {
    if (open $log,'>>',"$log/sex.log") {
      flock $log,LOCK_EX;
      seek $log,0,SEEK_END;
      printf {$log} $msg;
      close $log;
    }
  }
}

sub sigdie {
  local $_ = shift;
  chomp;
  sigexit('DIE',$_);
}

sub sigexit {
  my ($sig) = @_;
  my $msg = "@_";

  $msg =~ s/\n/ /g;
  $msg =~ s/\s+$//;
  $msg = sprintf "%s %s (%s) caught SIGNAL %s\n",
                 isodate(time),$user||'-',$fra||'-',$msg;

  foreach my $log (@logdir) {
    if (open $log,'>>',"$log/sex.log") {
      flock $log,LOCK_EX;
      seek $log,0,SEEK_END;
      printf {$log} $msg;
      close $log;
    }
  }
  if ($sig eq 'DIE') {
    shift;
    die "@_\n";
  } else {
    die "SIGNAL @_\n";
  }
}

sub error {
  nvt_print("HTTP/1.1 @_");
  exit;
}

sub header {
  my ($status,$type) = @_;

  return if $HTTP_HEADER;
  $HTTP_HEADER = $status;

  nvt_print("HTTP/1.1 $status");
  if ($mode eq 'POP') {
    nvt_print("Server: sexsrv");
    if ($type eq 'GZIP') {
      nvt_print("Content-Type: application/gzip");
    } else {
      nvt_print("Content-Type: application/binary");
    }
    nvt_print("Expires: 0");
    nvt_print("Cache-Control: no-cache");
    nvt_print("Connection: close");
  }
  nvt_print("");
}

sub authentificate {
  my $rid;

  error(400,"Missing auth-ID") unless $id;
  open $id,'<','@' or error(401,"$user/@ - $!");
  chomp($rid = <$id>||'');
  close $id;
  if ($rid and $sid and $id =~ /^(MD5H:)/) {
    $rid = $1 . md5_hex($rid.$sid);
  }
  error(401,"Wrong auth-ID") if $rid ne $id;
}