Convert::BulkDecoder - Extract (binary) data from mail and news messages

  use Convert::BulkDecoder;
  my $cvt = new Convert::BulkDecoder::;
  # Collect the articles into an array ref.
  my $art = [<>];
  # Decode.
  my $res =  $cvt->decode($art);
  die("Failed!") unless $res eq "OK";
  print "Extracted ", $cvt->{size}, " bytes to file ", $cvt->{file}, "\n";

package Convert::BulkDecoder;

# Convert::BulkDecoder - Extract binary data from mail and news messages
# RCS Info        : $Id: BulkDecoder.pm,v 1.12 2005-06-19 17:35:38+02 jv Exp $
# Author          : Johan Vromans
# Created On      : Wed Jan 29 16:59:58 2003
# Last Modified By: Johan Vromans
# Last Modified On: Sun Jun 19 17:34:31 2005
# Update Count    : 88
# Status          : Unknown, Use with caution!

$VERSION = "1.03";

use strict;
use integer;

sub new {
    my ($pkg, %atts) = @_;
    $pkg = ref $pkg if ref $pkg;

    my $self = bless {
        # Set explicit defaults.
	tmpdir   => "/var/tmp",
	destdir  => "",
        force    => 0,
	verbose  => 1,
	crc      => 1,
	md5      => 1,
	debug    => 0,
	neat     => \&_neat,
    }, $pkg;

    # Copy constructor attributes.
    foreach ( keys(%$self) ) {
	if ( defined($atts{$_}) ) {
	    $self->{$_} = delete($atts{$_});
	}
    }

    # Bail of if any remain.
    my $err = "";
    foreach my $k ( sort keys %atts ) {
	$err .= $pkg . ": invalid constructor attribute: $k\n";
    }
    die($err) if $err;

    # Polish.
    foreach ( $self->{destdir}, $self->{tmpdir} ) {
	next unless $_;
	$_ .= "/";
	s;/+$;/;;
    }

    if ( $self->{md5} ) {
	require Digest::MD5;
	$self->{_md5} = Digest::MD5->new;
    }

    $self;
}

sub decode {

    my ($self, $a) = @_;

    # Try uudecode, or find out better.
    my $ret = $self->uudecode($a);

    # MIME.
    $ret = $self->mimedecode($a) if $ret eq 'M';

    # yEnc.
    $ret = $self->ydecode($a) if $ret =~ /^Y/;

    # UNSUPPORTED -- FOR TESTING ONLY!
    # $ret = $self->ydecode_ydecode($a, $1) if $ret =~ /^Y(.*)/;

    $ret;
}

sub uudecode {
    my ($self, $a) = @_;

    my $doing = 0;
    my $size = 0;
    my $name;
    $self->{result} = "EMPTY";

    # Process the message lines.
    foreach ( @$a ) {
	if ( $doing ) {		# uudecoding...
	    if ( /^end/ ) {
		close(OUT);
		$self->{md5} = $self->{_md5}->b64digest if $self->{md5};
		$self->{size} = $size;
		$doing = 2;	# done
		$self->{result} = "OK";
		last;
	    }
	    # Select lines to process.
	    next if /[a-z]/;
	    next unless int((((ord() - 32) & 077) + 2) / 3)
	      == int(length() / 4);
	    # Decode.
	    my $t = unpack("u",$_);
	    print OUT $t or die("print(".$self->{file}."): $!\n");
	    $size += length($t);
	    $self->{_md5}->add($t) if $self->{md5};
	    next;
	}

	# Check for MIME.
	if ( m;^content-type:.*(image/|multipart);i ) {
	    return 'M';		# MIME
	}

	if ( m/^=ybegin\s+.*\s+name=(.+)/i ) {
	    return "Y$1";	# yEnc
	}

	# Otherwise, search for the uudecode 'begin' line.
	if ( /^begin\s+\d+\s+(.+)$/ ) {
	    $name = $self->{neat}->($1);
	    $self->{type} = "U";
	    $self->{name} = $name;
	    $self->{file} = $self->{destdir} . $name;
	    $doing = 2;		# Done
	    warn("Decoding(UU) to ", $self->{file}, "\n")
	      if $self->{verbose};
	    # Skip duplicates.
	    # Note that testing for -s fails if it is a
	    # notexisting symlink.
	    if ( (-l $self->{file} || -s _ ) && !$self->{force} ) {
		$self->{size} = -s _;
		$self->{result} = "DUP";
		last;
	    }

	    open (OUT, ">".$self->{file})
	      or die("create(".$self->{file}."): $!\n");
	    binmode(OUT);
	    $doing = 1;		# Doing
	    $self->{result} = "FAIL";
	    next;
	}
    }
    push(@{$self->{parts}},
	 { type   => $self->{type},
	   size   => $self->{size},
	   md5    => $self->{md5},
	   result => $self->{result},
	   name   => $self->{name},
	   file   => $self->{file} });
    return $self->{result};
}

my @crctab;

sub ydecode {
    my ($self, $a) = @_;
    $self->{type} = "Y";
    $self->{result} = "EMPTY";

    _fill_crctab() unless @crctab || !$self->{crc};

    my @lines = @$a;

    my ($ydec_part, $ydec_line, $ydec_size, $ydec_name, $ydec_pcrc,
	$ydec_begin, $ydec_end);
    my $pcrc;

    while ( $_ = shift(@lines) ) {
	# Newlines a fakes and should not be decoded.
	chomp;
	s/\r//g;
	# If we've started decoding $ydec_name will be set.
	if ( !$ydec_name  ) {
	    # Skip until beginning of yDecoded part.
	    next unless /^=ybegin/;
	    if ( / part=(\d+)/ ) {
		$ydec_part = $1;
	    }

	    if ( / size=(\d+)/ ) {
		$self->{size} = $ydec_size = $1;
	    }
	    else {
		die("Mandatory field 'size' missing\n");
	    }
	    if ( / line=(\d+)/ ) {
		$ydec_line = $1;
	    }
	    if( / name=(.*)$/ ) {
		$ydec_name = $self->{neat}->($1);
		$self->{file} = $self->{destdir} . $ydec_name;
		$self->{name} = $ydec_name;
		if ( !defined($ydec_part) || $ydec_part == 1 ) {
		    warn("Decoding(yEnc) to ", $self->{file}, "\n")
		      if $self->{verbose};
		    if ( -s $self->{file} ) {
			if ( $self->{force} ) {
			    unlink($self->{file});
			}
			else {
			    $self->{size} = -s _;
			    $self->{result} = "DUP";
			    last;
			}
		    }
		}
	    }
	    else {
		die("Unknown attach name\n");
	    }

	    # Multipart messages contain more information on.
	    # the second line.
	    if ( $ydec_part ) {
		$_ = shift(@lines);
		chomp;
		s/\r//g;
		if ( /^=ypart/ ) {
		    if ( / begin=(\d+)/ ) {
			# We need this to check if the size of this message
			# is correct.
			$ydec_begin = $1;
			$pcrc = 0xffffffff;
			undef $ydec_pcrc;
		    }
		    else {
			warn("No begin field found in part, ignoring\n");
			undef $ydec_part;
		    }
		    if ( / end=(\d+)/ ) {
			# We need this to calculate the size of this message.
			$ydec_end = $1;
		    }
		    else {
			warn("No end field found in part, ignoring");
			undef $ydec_part;
		    }
		}
		else {
		    warn("Article described as multipart message, however ".
			 "it doesn't seem that way\n");
		    undef $ydec_part;
		}
	    }
	    else {
		$pcrc = 0xffffffff;
	    }

	    # If the $ydec_part is different from 1
	    # we need to open the file for appending.
	    if ( -e $self->{file} ) {
		if ( defined($ydec_part) && $ydec_part != 1 ) {
		    # If we have a multipart message, the file exists
		    # and we are not at the first part, we should just
		    # open the file as an append. We assume that this is
		    # the multipart we were already processing.
		    #print "Opening $ydec_name for appending\n";
		    if ( !open(OUT, ">>".$self->{file}) ) {
			die("Couldn't open ".$self->{file}.
			    " for appending: $!\n");
		    }
		}
		elsif ( !open(OUT, ">".$self->{file}) ) {
		    die("Couldn't create ".$self->{file}.": $!\n");
		}
	    }
	    else {
		# File doesn't exist. We open it for writing O' so plain.
		if ( defined($ydec_part) && $ydec_part != 1 ) {
		    die("Missing  ".$self->{file}. " for appending: $!\n");
		}
		if ( !open(OUT, ">".$self->{file}) ) {
		    die("Couldn't create ".$self->{file}.": $!\n");
		}
		$self->{result} = "FAIL";
	    }
	    # Cancel any file translations.
	    binmode(OUT);
	    # Excellent.. We have determed all the info for this file we
	    # need.. Skip till next line, this should contain the real
	    # data.
	    next;
	}

	# Looking for the end tag.
	if ( /^=yend/ ) {
	    # We are done.. Check the sanity of article.
	    # and unset $ydec_name in case that there are more
	    # ydecoded files in the same article.
	    $self->{result} = "OK";
	    if ( / part=(\d+)/ ) {
		if ( $ydec_part != $1 ) {
		    die("Part number '$1' different from beginning part '$ydec_part'\n");
		}
	    }
	    if ( / size=(\d+)/ ) {
		# Check size, but first calculate it.
		my $size;
		if ( defined($ydec_part) ) {
		    $size = ($ydec_end - $ydec_begin + 1);
		}
		else {
		    $size = $ydec_size;
		}
		if ( $1 != $size ) {
		    die("Size '$1' different from beginning size '$size'\n");
		}
	    }
	    if ( / pcrc32=([0-9a-f]+)/i && @crctab ) {
		if ( defined($ydec_pcrc) && ($ydec_pcrc != $1) ) {
		    die("CRC '$1' different from beginning CRC '$ydec_pcrc'\n");
		}
		$ydec_pcrc = hex($1);
		$pcrc = $pcrc ^ 0xffffffff;
		if ( $pcrc == $ydec_pcrc ) {
		    warn("Part $ydec_part, checksum OK\n")
		      if $self->{verbose};
		}
		else {
		    warn(sprintf("Part $ydec_part, checksum mismatch, ".
				 "got 0x%08x, expected 0x%08x\n",
				 $pcrc, $ydec_pcrc));
		}

	    }
	    if ( !defined($ydec_part) && / crc32=([0-9a-f]+)/i && @crctab ) {
		$ydec_pcrc = hex($1);
		$pcrc = $pcrc ^ 0xffffffff;
		if ( $pcrc == $ydec_pcrc ) {
		    warn("Checksum OK\n")
		      if $self->{verbose};
		}
		else {
		    warn(sprintf("Checksum mismatch, ".
				 "got 0x%08x, expected 0x%08x\n",
				 $pcrc, $ydec_pcrc));
		}

	    }
	    undef $ydec_name;
	    # Dont encode the endline, we skip to the next line
	    # in search for any more parts.
	    next;
	}

	# If we got here, we are within an encoded article, an
	# we will take meassures to decode it.
	# We decode line by line.

	# Decoder by jvromans@squirrel.nl.
	s/=(.)/chr(ord($1)+(256-64) & 255)/ge;
	tr{\000-\377}{\326-\377\000-\325};

	my $data = $_;
	# CRC check code by jvromans@squirrel.nl.
	if ( @crctab ) {
	    foreach ( split(//, $data) ) {
		$pcrc = $crctab[($pcrc^ord($_))&0xff] ^ (($pcrc >> 8) & 0x00ffffff);
	    }
	}

	print OUT $data;
	$self->{_md5}->add($data) if $self->{md5};
    }

    close(OUT);
    $self->{md5} = $self->{_md5}->b64digest if $self->{md5};
    push(@{$self->{parts}},
	 { type   => $self->{type},
	   size   => $self->{size},
	   md5    => $self->{md5},
	   result => $self->{result},
	   name   => $self->{name},
	   file   => $self->{file} });
    return $self->{result};
}

sub _fill_crctab {
    @crctab = 
      ( 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
	0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
	0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
	0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
	0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
	0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
	0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
	0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
	0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
	0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
	0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
	0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
	0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
	0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
	0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
	0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
	0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
	0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
      );
}

sub ydecode_ydecode {
    my ($self, $a, $name) = @_;
    my $tmp = $self->{tmpdir} . "mfetch.$$.";

    $self->{type} = "Y";
    if ( $name ) {
	$self->{file} = $self->{destdir} . $name;
	warn("Decoding(ydecode) to ", $self->{file}, "\n")
	  if $self->{verbose};
	if ( -s $self->{file} ) {
	    if ( $self->{force} ) {
		unlink($self->{file});
	    }
	    else {
		$self->{size} = -s _;
		$self->{result} = "DUP";
		goto QXIT;
	    }
	}
    }

    my @files;
    my $copy = 0;
    my $part;
    foreach ( @$a ) {
	if ( $copy && /^=yend/ ) {
	    print TMP $_;
	    close(TMP);
	    $copy = 0;
	    next;
	}
	if ( !$copy && /^=ybegin.*\s+part=(\d+)/ ) {
	    my $file = sprintf("$tmp%03d", $part = $1);
	    $files[$1-1] = $file;
	    $copy = $1 if /\s+line=(\d+)/;
	    $self->{size} = $1 if /\s+size=(\d+)/;
	    $self->{name} = $1 if /\s+name=(.+)/;
	    $self->{file} = $self->{destdir} . $self->{name};
	    if ( -s $self->{file} ) {
		if ( $self->{force} ) {
		    unlink($self->{file});
		}
		else {
		    $self->{size} = -s _;
		    $self->{result} = "DUP";
		    goto QXIT;
		}
	    }
	    open(TMP, ">$file") || die("$file: $!\n");
	    binmode(TMP);
	    $copy++;
	}
	if ( $copy > 1 ) {	# check length
	    # If it starts with an unescaped period, the line will be
	    # one too short. Add the period since ydecode requires it.
	    if ( /^\./ && length($_) == $copy ) {
		$_ = ".$_";
	    }
	}
	print TMP $_ if $copy;
    }

    system("ydecode", "-k",
	   $self->{destdir} ? "--output=".$self->{destdir} : (),
	   @files);

    $self->{result} = "FAIL";
    if ( -s $self->{file} == $self->{size} ) {
	unlink(@files);
	if ( $self->{md5} ) {
	    open(F, $self->{file})
	      or die($self->{file} . " (reopen) $!\n");
	    binmode(F);
	    local($/) = undef;
	    $self->{_md5}->add(<F>);
	    close(F);
	    $self->{md5} = $self->{_md5}->b64digest;
	}
	$self->{result} = "OK";
    }
QXIT:
    push(@{$self->{parts}},
	 { type   => $self->{type},
	   size   => $self->{size},
	   md5    => $self->{md5},
	   result => $self->{result},
	   name   => $self->{name},
	   file   => $self->{file} });
    return $self->{result};
}

sub mimedecode {
    my ($self, $a) = @_;

    require MIME::Parser;

    $self->{type} = "M";
    my $parser = new MIME::Parser;
    # Store everything in memory.
    $parser->output_to_core(1);
    my $e = $parser->parse_data($a);

    unless ( defined $e->{ME_Parts} &&  @{$e->{ME_Parts}} ) {
	$e->{ME_Parts} = [ $e ];
    }

    foreach my $part ( @{$e->{ME_Parts}} ) {
	my $name;
	foreach ( 'Content-Type', 'Content-Disposition' ) {

	    my $ct = $part->{mail_inet_head}->{mail_hdr_hash}->{$_};
	    next unless defined $ct && defined ($ct = ${$ct->[0]});
	    if ( $ct =~ m{((file)?name)="([^"]+)"}i ) {
		$name = $self->{name} = $self->{neat}->($3);
		$self->{file} = $self->{destdir} . $name;
		warn("Decoding(MIME) to ", $self->{file}, "\n")
		  if $self->{verbose};
		if ( -s $self->{file} && !$self->{force} ) {
		    $self->{size} = -s _;
		    $self->{result} = "DUP";
		    push(@{$self->{parts}},
			 { type   => $self->{type},
			   size   => $self->{size},
			   result => $self->{result},
			   name   => $self->{name},
			   file   => $self->{file} });
		    next;
		}
	    }
	}

	# Skip body.
	next unless $name;
	next if $name eq $self->{destdir}."body";

	# Skip duplicates.
	if ( -s $name && !$self->{force} ) {
	    $self->{size} = -s _;
	    $self->{result} = "DUP";
	    push(@{$self->{parts}},
		 { type   => $self->{type},
		   size   => $self->{size},
		   result => $self->{result},
		   name   => $self->{name},
		   file   => $self->{file} });
	    next;
	}

	# Store it.
	my $bh = $part->{ME_Bodyhandle};
	if ( $bh && defined $bh->{MBC_Data} && open (OUT, ">".$self->{file}) ) {
	    binmode(OUT);
	    my $size = 0;
	    foreach ( @{$bh->{MBC_Data}} ) {
		print OUT $_;
		$self->{_md5}->add($_) if $self->{md5};
		$size += length($_);
	    }
	    close (OUT);
	    $self->{md5} = $self->{_md5}->b64digest if $self->{md5};
	    $self->{size} = $size;
	    $self->{result} = "OK";
	    push(@{$self->{parts}},
		 { type   => $self->{type},
		   size   => $self->{size},
		   md5    => $self->{md5},
		   result => $self->{result},
		   name   => $self->{name},
		   file   => $self->{file} });
	}
	else {
	    $self->{result} = "FAIL";
	    push(@{$self->{parts}},
		 { type   => $self->{type},
		   result => $self->{result},
		   name   => $self->{name},
		   file   => $self->{file} });
	}
    }

    # Return values for the first file.
    while ( my($k,$v) = each(%{$self->{parts}->[0]}) ) {
	$self->{$k} = $v;
    }
    return $self->{result};

}

sub _neat {
    local ($_) = @_;
    s/^\[a-z]://i;
    s/^.*?([^\\]+$)/$1/;
    # Spaces and unprintables to _.
    s/\s+/_/g;
    s/\.\.+/./g;
    s/[\0-\040'`"\177-\240\/]/_/g;
    # Remove leading dots.
    s/^\.+//;
    $_;
}

1;

__END__