private static Encoding ParseBodyEncoding(string characterSet)
{
Encoding encoding = Encoding.ASCII;
if (!string.IsNullOrEmpty(characterSet))
{
encoding = EncodingFinder.FindEncoding(characterSet);
}
return(encoding);
}
public static string Decode(string encodedWords)
{
if (encodedWords == null)
{
throw new ArgumentNullException("encodedWords");
}
const string encodedWordRegex = @"\=\?(?<Charset>\S+?)\?(?<Encoding>\w)\?(?<Content>.+?)\?\=";
const string replaceRegex = @"(?<first>" + encodedWordRegex + @")\s+(?<second>" + encodedWordRegex + ")";
encodedWords = Regex.Replace(encodedWords, replaceRegex, "${first}${second}");
encodedWords = Regex.Replace(encodedWords, replaceRegex, "${first}${second}");
string decodedWords = encodedWords;
MatchCollection matches = Regex.Matches(encodedWords, encodedWordRegex);
foreach (Match match in matches)
{
if (!match.Success)
{
continue;
}
string fullMatchValue = match.Value;
string encodedText = match.Groups["Content"].Value;
string encoding = match.Groups["Encoding"].Value;
string charset = match.Groups["Charset"].Value;
Encoding charsetEncoding = EncodingFinder.FindEncoding(charset);
string decodedText;
switch (encoding.ToUpperInvariant())
{
case "B":
decodedText = Base64Decode(encodedText, charsetEncoding);
break;
case "Q":
decodedText = QuotedPrintable.DecodeEncodedWord(encodedText, charsetEncoding);
break;
default:
throw new ArgumentException("The encoding " + encoding + " was not recognized");
}
decodedWords = decodedWords.Replace(fullMatchValue, decodedText);
}
return(decodedWords);
}