| #!/usr/bin/perl -wT |
| use strict; |
| use CGI; |
| use Encode; |
| |
| my $cgi = new CGI; |
| |
| use constant Unicode16BitEscapeSequenceLength => 6; # e.g. %u26C4 |
| my $unicode16BitEscapeSequenceRegEx = qr#%u([0-9A-Za-z]{1,4})#; |
| |
| sub isUTF16Surrogate($) |
| { |
| my ($number) = @_; |
| return $number >= 0xD800 && $number <= 0xDFFF; |
| } |
| |
| # See <http://en.wikipedia.org/wiki/Percent-encoding#Non-standard_implementations>. |
| sub decodeRunOf16BitUnicodeEscapeSequences($) |
| { |
| my ($string) = @_; |
| my @codeUnits = grep { length($_) } split(/$unicode16BitEscapeSequenceRegEx/, $string); |
| my $i = 0; |
| my $decodedRun = ""; |
| while ($i < @codeUnits) { |
| # FIXME: We fallback to the UTF-8 character if we don't receive a proper high and low surrogate pair. |
| # Instead, we should add error handling to detect high/low surrogate mismatches and sequences |
| # of the form low surrogate then high surrogate. |
| my $hexDigitValueOfPossibleHighSurrogate = hex($codeUnits[$i]); |
| if (isUTF16Surrogate($hexDigitValueOfPossibleHighSurrogate) && $i + 1 < @codeUnits) { |
| my $hexDigitValueOfPossibleLowSurrogate = hex($codeUnits[$i + 1]); |
| if (isUTF16Surrogate($hexDigitValueOfPossibleLowSurrogate)) { |
| $decodedRun .= decode("UTF-16LE", pack("S2", $hexDigitValueOfPossibleHighSurrogate, $hexDigitValueOfPossibleLowSurrogate)); |
| $i += 2; |
| next; |
| } |
| } |
| $decodedRun .= chr($hexDigitValueOfPossibleHighSurrogate); |
| $i += 1; |
| } |
| return $decodedRun; |
| } |
| |
| sub decode16BitUnicodeEscapeSequences |
| { |
| my ($string) = @_; |
| my $stringLength = length($string); |
| my $searchPosition = 0; |
| my $encodedRunPosition = 0; |
| my $decodedPosition = 0; |
| my $result = ""; |
| while (($encodedRunPosition = index($string, "%u", $searchPosition)) >= 0) { |
| my $encodedRunEndPosition = $encodedRunPosition; |
| while ($stringLength - $encodedRunEndPosition >= Unicode16BitEscapeSequenceLength |
| && substr($string, $encodedRunEndPosition, Unicode16BitEscapeSequenceLength) =~ /$unicode16BitEscapeSequenceRegEx/) { |
| $encodedRunEndPosition += Unicode16BitEscapeSequenceLength; |
| } |
| $searchPosition = $encodedRunEndPosition; |
| if ($encodedRunEndPosition == $encodedRunPosition) { |
| ++$searchPosition; |
| next; |
| } |
| $result .= substr($string, $decodedPosition, $encodedRunPosition - $decodedPosition); |
| $result .= decodeRunOf16BitUnicodeEscapeSequences(substr($string, $encodedRunPosition, $encodedRunEndPosition - $encodedRunPosition)); |
| $decodedPosition = $encodedRunEndPosition; |
| } |
| $result .= substr($string, $decodedPosition); |
| return $result; |
| } |
| |
| my $charsetToUse = $cgi->param('charset') ? $cgi->param('charset') : "UTF-8"; |
| print "Content-Type: text/html; charset=$charsetToUse\n\n"; |
| |
| print "<!DOCTYPE html>\n"; |
| print "<html>\n"; |
| print "<body>\n"; |
| print decode16BitUnicodeEscapeSequences($cgi->param('q')); |
| print "</body>\n"; |
| print "</html>\n"; |
