在Go中多路复用可以处理非HTTP协议的HTTP服务器的正确方法

Question

I have built a router with extended logging capabilities using Go. It works properly for most use cases. However, it encounters problems when clients send non-standard HTTP messages on port 80.

To date, I have solved this by implementing my own version of ServeHTTP():

func (myproxy *MyProxy) ServeHTTP(w http.ResponseWtier, r *http.Request) {

  // Inspect headers
  // Determine if it is a custom protocol (ie: websockets, CONNECT requests)
  // Implement handlers for each time
} 

In the event that I determine a request is a non-standard HTTP protocol, the request is played back to the original destination (via http.Request.Write()) and everyone is happy.

At least, most of the time. The problem arises with edge cases. Tivo clients do not send "Host" headers and appear to not like all kinds of other standard things that Go does (such as capitalizing header names). The number of possible variations on this is endless so what I would very much like to do is to buffer the original request - exactly as it was sent to me without any modifications - and replay it back to the original destination server.

I could hack this by re-implementing net.Http.Server, but this seems like an extraordinarily difficult and brittle approach. Would I would prefer to do would be to somehow hook into net/http/http/server.go right around the point where it receives a connection, then wrap that in a spy wrapper that logs the request to a buffer.

func (srv *Server) Serve(l net.Listener) error {

        // Lots of listener code...

    c := srv.newConn(rw)
    c.setState(c.rwc, StateNew) // before Serve can return

        // I'd like to wrap c here and save the request for possible reply later.
    go c.serve(ctx)
}

https://golang.org/src/net/http/server.go?s=93229:93284#L2805

Edit: I have looked at httpUtil:DumpRequest but this slightly modifies the original request (changes case and order of headers). If it didn't do that, it would be an ideal solution.

https://godoc.org/net/http/httputil#DumpRequest

Is there a way to hook connections around this point before they are parsed by http.Request?

Answer 1

In the interest of helping others, I wanted to answer my question. The approach I suggested above does in fact work and is the proper way to do this. In summary:

• Implement ListenAndServe()
• Wrap the incoming net.Conn in a TeeReader or other multiplexed connection wrapper
• Record the request
• Dial the original destination and connect with the inbound connection, replaying the original request if necessary.

A similar use case is required when upgrading connection requests for websockets servers. A nice writeup can be found here:

https://medium.freecodecamp.org/million-websockets-and-go-cc58418460bb