How Can I Preserve Literal Slashes in URL-Encoded HTTP GET Requests?

Encoding URLs: Preserving the Literal Slash in HTTP GETs

In HTTP GET requests, URL-encoding is crucial for transmitting special characters that are not part of the standard character set. However, when a URL path contains a slash (/), certain GET implementations automatically translate it into the double slash (//) syntax. This can be problematic when transmitting URL-encoded slash characters, as they are essential for compliance with protocols like OCSP over HTTP/GET.

The following code snippet illustrates the issue:

using (WebClient webClient = new WebClient())
{
  webClient.DownloadData("http://example.com/%2F");
}

However, the actual request sent to the server is:

GET // HTTP/1.1
Host: example.com
Connection: Keep-Alive

To retain the literal slash in HTTP GETs, a custom solution is required. Here's a code snippet that modifies the Uri object to preserve the path and query:

Uri uri = new Uri("http://example.com/%2F");
ForceCanonicalPathAndQuery(uri);
using (WebClient webClient = new WebClient())
{
  webClient.DownloadData(uri);
}

void ForceCanonicalPathAndQuery(Uri uri){
  string paq = uri.PathAndQuery; // need to access PathAndQuery
  FieldInfo flagsFieldInfo = typeof(Uri).GetField("m_Flags", BindingFlags.Instance | BindingFlags.NonPublic);
  ulong flags = (ulong) flagsFieldInfo.GetValue(uri);
  flags &= ~((ulong) 0x30); // Flags.PathNotCanonical|Flags.QueryNotCanonical
  flagsFieldInfo.SetValue(uri, flags);
}

By modifying the Uri object, the path is forced to remain in its original state, ensuring that the literal slash is preserved in the GET request. This solution allows for compliant implementation of protocols that require URL-encoded slashes.

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