Why Are request.URL.Host and request.URL.Scheme Blank in My Go HTTP Development Server?

Analyzing the Absence of Host and Scheme in Development Server Requests

When implementing a simple HTTP server in Go using the http package, you might encounter blank values for request.URL.Host and request.URL.Scheme during development. This can be perplexing since you expect these fields to provide information about the request. Let's investigate why this behavior occurs and explore ways to obtain the missing data.

In your example code, the request message is received through a relative path. This means the client's HTTP request does not include an absolute URL with a clearly specified host and scheme. Instead, the client employs a relative path, leaving these fields blank.

However, if the request was made through an HTTP proxy or using an absolute URL, the request.URL.Host and request.URL.Scheme would be populated, as the proxy or client would supply this information explicitly.

To confirm this, you can test your server with different request formats using a tool like netcat. Sending a request with a relative path will yield blank Host and Scheme fields, while using an absolute URL will populate them.

As an alternative to relying solely on request.URL.Host, you can access the Host field directly from the http.Request struct, which will provide the host information regardless of whether the request uses a relative or absolute path.

Additionally, you can check if the request received by your handler is absolute or relative using the IsAbs() method of the request.URL struct. This allows you to handle requests with relative paths appropriately.

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