Quoted printable subject decoded wrong

[meehi]

Received a mail with the following subject: H=C3=BAsv=C3=A9ti=20=C3=9Cnnepeket!

Related to this site: http://www.convertstring.com/EncodeDecode/QuotedPrintableDecode it should look like this: Húsvéti Ünnepeket!

The function in Utilities.cs internal static string DecodeWords(string encodedWords) resulting the following instead: Húsvéti ??nnepeket!

So this function does not recognize the Ü character.

[meehi]

Here is the complete subject value: "=?UTF-8?Q?H=C3=BAsv=C3=A9ti=20=C3=9Cnnepeket!?="

[meehi]

I have fixed this issue with the following code block replacement:

internal static string DecodeWords(string encodedWords)
        {
            if (string.IsNullOrEmpty(encodedWords))
                return string.Empty;

            string decodedWords = encodedWords;

            // Notice that RFC2231 redefines the BNF to
            // encoded-word := "=?" charset ["*" language] "?" encoded-text "?="
            // but no usage of this BNF have been spotted yet. It is here to
            // ease debugging if such a case is discovered.

            // This is the regex that should fit the BNF
            // RFC Says that NO WHITESPACE is allowed in this encoding, but there are examples
            // where whitespace is there, and therefore this regex allows for such.
            const string strRegEx = @"\=\?(?<Charset>\S+?)\?(?<Encoding>\w)\?(?<Content>.+?)\?\=";
            // \w   Matches any word character including underscore. Equivalent to "[A-Za-z0-9_]".
            // \S   Matches any nonwhite space character. Equivalent to "[^ \f\n\r\t\v]".
            // +?   non-gready equivalent to +
            // (?<NAME>REGEX) is a named group with name NAME and regular expression REGEX

            var matches = Regex.Matches(encodedWords, strRegEx);
            foreach (Match match in matches)
            {
                // If this match was not a success, we should not use it
                if (!match.Success)
                    continue;

                string fullMatchValue = match.Value;
                //new version start
                System.Net.Mail.Attachment attachment = System.Net.Mail.Attachment.CreateAttachmentFromString("", fullMatchValue);
                string decodedText = attachment.Name;
                //new version end

                /*remove start
                string encodedText = match.Groups["Content"].Value;
                string encoding = match.Groups["Encoding"].Value;
                string charset = match.Groups["Charset"].Value;

                // Get the encoding which corrosponds to the character set
                Encoding charsetEncoding = ParseCharsetToEncoding(charset);

                // Store decoded text here when done
                string decodedText;

                // Encoding may also be written in lowercase
                switch (encoding.ToUpperInvariant())
                {
                    // RFC:
                    // The "B" encoding is identical to the "BASE64" 
                    // encoding defined by RFC 2045.
                    // http://tools.ietf.org/html/rfc2045#section-6.8
                    case "B":
                        decodedText = DecodeBase64(encodedText, charsetEncoding);
                        break;

                    // RFC:
                    // The "Q" encoding is similar to the "Quoted-Printable" content-
                    // transfer-encoding defined in RFC 2045.
                    // There are more details to this. Please check
                    // http://tools.ietf.org/html/rfc2047#section-4.2
                    // 
                    case "Q":
                        decodedText = DecodeQuotedPrintable(encodedText, charsetEncoding);
                        break;

                    default:
                        throw new ArgumentException("The encoding " + encoding + " was not recognized");
                }
                remove end*/

                // Repalce our encoded value with our decoded value
                decodedWords = decodedWords.Replace(fullMatchValue, decodedText);
            }

            return decodedWords;
        }

[andyedinborough]

Thanks for submitting this. The function that decodes quoted printable was fairly messy anyway. I've rewritten the bulk of it, removing the dependency on regular expressions.

[meehi]

Thanks, that's working.

[meehi]

The decoder working just fine but it's removing whitecharacters now like \r\n. May I reopen this issue? :)

[andyedinborough]

Sorry about that, there were a couple lines I forgot to remove. Working now?

[meehi]

Yes, thanks. Now it's perfect.