Access `Request` headers set by library before or after sending request

[alexkreidler]

I'm writing a library that uses Reqwest and serializes the Request and Response structs to WARC files.

It works great for the Responses, but with Requests it only shows me the headers I've set myself, because I'm using the Request struct before it is passed into the library.

Thus, it doesn't show any library-set headers like User-Agent, I'd guess Accept when the user doesn't set it, and Content-Length (see #1030).

It would be great if we could get access to the Request object as it looks after any library modifications. For my situation, I'm fine getting the Request headers before or after sending request, but I can imagine some folks who would access to it before sending.

I'm not sure if Hyper also sets default headers, in which case this would be more complicated.

Let me know what you think!

[dechamps]

I ran into the same issue for essentially the same use case, trying to instrument reqwest calls into HAR files to make my code easier to debug/troubleshoot. It would be nice if Request::headers() could return a more accurate representation of the actual headers that will be sent in the request, including the user agent.

[jeremyandrews]

I've run into this same problem, I need to log request headers for debugging purposes and I'm only able to see the headers I set manually with a RequestBuilder. The headers added by the Client are opaque to my application: is there any way to access them?

[jeremyandrews]

This appears to be a duplicate of #788 and #314 and #264