Move Linux client & common packages into a public repo.

derp/derphttp/derphttp_server.go

@@ -0,0 +1,35 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package derphttp
+
+import (
+	"net/http"
+
+	"tailscale.com/derp"
+)
+
+func Handler(s *derp.Server) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Header.Get("Upgrade") != "WebSocket" {
+			http.Error(w, "DERP requires connection upgrade", http.StatusUpgradeRequired)
+			return
+		}
+		w.Header().Set("Upgrade", "WebSocket")
+		w.Header().Set("Connection", "Upgrade")
+		w.WriteHeader(http.StatusSwitchingProtocols)
+
+		h, ok := w.(http.Hijacker)
+		if !ok {
+			http.Error(w, "HTTP does not support general TCP support", 500)
+			return
+		}
+		netConn, conn, err := h.Hijack()
+		if err != nil {
+			http.Error(w, "HTTP does not support general TCP support", 500)
+			return
+		}
+		s.Accept(netConn, conn)
+	})
+}