decode-mail.pl

#!/usr/bin/perl

use MIME::Base64;
use MIME::QuotedPrint::Perl;

my $mail_file = $ARGV[0];

open( FILE, $mail_file) or die "$!";
my $mail_content = "";
while ( <FILE> ) {
  $mail_content .= $_;
}
close( FILE );

# Content-Transfer-Encoding が含まれる場合はBoundary処理します。
if ( $mail_content =~ /Content-Transfer-Encoding/ ) {
  if ( $mail_content =~ /^(--[a-zA-Z0-9\-]+)[\s]*?$/m ) {
    my @contents = split( $1, $mail_content );
    foreach my $content( @contents ) {
      $encoding = "";
      $transfered = "";
      if ( $content =~ /^Content-Type: .*?charset=(.*?)[\s]?$/m ) {
        $encoding = $1;
      }
      if ( $content =~ /^Content-Transfer-Encoding: (.*?)[\s]?$/m ) {
        $transfered = $1;
      }

      # Content-Transfer-Encoding がないものは変換しようがないので無視します。
      if ( $encoding eq "" ) { $encoding = "UTF-8"; }
      if ( $transfered eq "" ) {
        next;
      }

      # ダブルクオーテーションを除去します。
      $encoding =~ s/"//g;
      $transfered =~ s/"//g;

      # 判定のために小文字に変換します。
      $encoding = lc( $encoding );
      $transfered = lc( $transfered );

      print $encoding . " / " . $transfered . "\n";

      $content =~ s/^[\r\n]*//;
      @splitted_content = split( /\r\n\r\n|\n\n|\r\r/, $content );
      if ( $transfered eq "base64" ) {
        $decoded_content = decode_base64( $splitted_content[1] );

      } elsif ( $transfered eq "quoted-printable" ) {
        $decoded_content = decode_qp( $splitted_content[1] );

      } elsif ( $transfered eq "7bit" ) {
        $decoded_content = $splitted_content[1];

      }
      print $decoded_content;
    }
  }
}


exit();