How-to workaround differences with Uri and encoded URLs in .Net4.0 vs .Net4.5 using HttpClient

Question

Uri behaves differently in .Net4.0 vs .Net4.5

var u = new Uri("http://localhost:5984/mycouchtests_pri/test%2F1");
Console.WriteLine(u.OriginalString);
Console.WriteLine(u.AbsoluteUri);

Outcome NET4.0

http://localhost:5984/mycouchtests_pri/test%2F1
http://localhost:5984/mycouchtests_pri/test/1

Outcome NET4.5

http://localhost:5984/mycouchtests_pri/test%2F1
http://localhost:5984/mycouchtests_pri/test%2F1

So when using the HttpClient distributed by Microsoft via NuGet requests like the above fail with .Net4.0, since the HttpRequestMessage is using the Uri.

Any ideas for a workaround?

EDIT There is a NON APPLICABLE workaround by adding configuration for <uri> in e.g. App.config or Machine.config (http://msdn.microsoft.com/en-us/library/ee656539(v=vs.110).aspx).

<configuration>
  <uri>
    <schemeSettings>
      <add name="http" genericUriParserOptions="DontUnescapePathDotsAndSlashes"/>
    </schemeSettings>
  </uri>
</configuration>

But as this is a tools library, that's not really an option. If the HttpClient for .Net4.0 is supposed to be on par with the one in .Net4.5, they should have the same behavior.

Answer 1

Mike Hadlow wrote a blog post on this a few years back. Here's the code he came up with to get round this:

private void LeaveDotsAndSlashesEscaped()
{
    var getSyntaxMethod = 
        typeof (UriParser).GetMethod("GetSyntax", BindingFlags.Static | BindingFlags.NonPublic);
    if (getSyntaxMethod == null)
    {
        throw new MissingMethodException("UriParser", "GetSyntax");
    }

    var uriParser = getSyntaxMethod.Invoke(null, new object[] { "http" });

    var setUpdatableFlagsMethod = 
        uriParser.GetType().GetMethod("SetUpdatableFlags", BindingFlags.Instance | BindingFlags.NonPublic);
    if (setUpdatableFlagsMethod == null)
    {
        throw new MissingMethodException("UriParser", "SetUpdatableFlags");
    }

    setUpdatableFlagsMethod.Invoke(uriParser, new object[] {0});
}

I think it just sets the flag that's available from .config in code, so while it's hacky, it's not exactly unsupported.