可以使用Go net / rpc检查元数据吗？

Examples of an RPC server in Go often look something like this (from https://golang.org/pkg/net/rpc/):

arith := new(Arith)
rpc.Register(arith)
rpc.HandleHTTP()
l, e := net.Listen("tcp", ":1234")
if e != nil {
    log.Fatal("listen error:", e)
}
go http.Serve(l, nil)

Is it possible to inspect the metadata associated with the connection before it is passed off to the registered function? I would like to check the client IP, API key, and requested function against an ACL first.

Edit to add: I realize that can get the remote address from the listener with l.RemoteAddr() - it isn't clear how I would get the API key, and requested function.

Once inside the function, I can get the API key, but not the client IP. Doing it inside the function is less than desirable because ACL check boilerplate would have to go in every function.

Regrettably, I have determined that this is not possible without forking net/rpc and adding context functionality to it.

Passing a context to the registered function appears to be a common feature request; however, per https://golang.org/pkg/net/rpc/, "The net/rpc package is frozen and is not accepting new features."