System.Uri and encoded colon (:)

Question

Before .Net 4.5, it seems that System.Uri would unencode encoded slashes, but this has since been fixed. Reference: https://stackoverflow.com/a/20733619/188740

I'm encountering the same problem with colons. System.Uri still unencodes encoded colons. Example:

 var uri = new Uri("http://www.example.com/?foo=http%3A%2F%2Fwww.example.com");
 var s = uri.ToString(); //http://www.example.com/?foo=http:%2F%2Fwww.example.com

Notice how %3A gets switched back to : by System.Uri. Is this a bug? What's the best workaround?

Answer 1

How about using Uri.AbsoluteUri instead?

var s = uri.AbsoluteUri; 
// http://www.example.com/?foo=http%3A%2F%2Fwww.example.com

As per the source, uri.ToString() looks like it has logic to unescape certain parts which can be seen here whereas .AbsoluteUri has a much simpler implementation.

Uri.ToString()

As per the MSDN documentation for System.Uri.ToString():

A String instance that contains the unescaped canonical representation of the Uri instance. All characters are unescaped except #, ?, and %.

However as per the example and after trying out a few more strings, it looks like the actual implementation is somwhat like 'Only :, * and spaces are unescaped'

%3A (:) // gets unescaped
%20 ( ) // gets unescaped 
%2A (*) // gets unescaped
%2b, %26, %23, %24, %25 (+, &, #, ,ドル %) // Remain as-is (escaped)

Other Links

• System.Uri.AbsoluteUri

• Johnny Oshika: AbsoluteUri works like a charm. Why do colons get unencoded without AbsoluteUri? Seems like a bug to me.
• degant: Yes looks like it. I believe the error is somewhere here which goes ahead and unescapes certain parts. Whereas .AbsoluteUri has a much simpler implementation.