Update dependencies

vendor/tailscale.com/derp/derphttp/derphttp_server.go

@@ -21,6 +21,8 @@ const fastStartHeader = "Derp-Fast-Start"
 // Handler returns an http.Handler to be mounted at /derp, serving s.
 func Handler(s *derp.Server) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+
 		// These are installed both here and in cmd/derper. The check here
 		// catches both cmd/derper run with DERP disabled (STUN only mode) as
 		// well as DERP being run in tests with derphttp.Handler directly,
@@ -66,7 +68,11 @@ func Handler(s *derp.Server) http.Handler {
 				pubKey.UntypedHexString())
 		}
 
-		s.Accept(r.Context(), netConn, conn, netConn.RemoteAddr().String())
+		if v := r.Header.Get(derp.IdealNodeHeader); v != "" {
+			ctx = derp.IdealNodeContextKey.WithValue(ctx, v)
+		}
+
+		s.Accept(ctx, netConn, conn, netConn.RemoteAddr().String())
 	})
 }
 
@@ -92,6 +98,7 @@ func ServeNoContent(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set(NoContentResponseHeader, "response "+challenge)
 		}
 	}
+	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate, no-transform, max-age=0")
 	w.WriteHeader(http.StatusNoContent)
 }
 
@@ -99,7 +106,7 @@ func isChallengeChar(c rune) bool {
 	// Semi-randomly chosen as a limited set of valid characters
 	return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') ||
 		('0' <= c && c <= '9') ||
-		c == '.' || c == '-' || c == '_'
+		c == '.' || c == '-' || c == '_' || c == ':'
 }
 
 const (