rpc: fix crash if websocket conn has no origin

rpc/json.go

@@ -142,6 +142,14 @@ type Conn interface {
 	SetWriteDeadline(time.Time) error
 }
 
+// connWithRemoteAddr overrides the remote address of a connection.
+type connWithRemoteAddr struct {
+	Conn
+	addr string
+}
+
+func (c connWithRemoteAddr) RemoteAddr() string { return c.addr }
+
 // jsonCodec reads and writes JSON-RPC messages to the underlying connection. It also has
 // support for parsing arguments and serializing (result) objects.
 type jsonCodec struct {
@@ -166,12 +174,12 @@ func NewCodec(conn Conn, encode, decode func(v interface{}) error) ServerCodec {
 	}
 
 	// Try to figure out the remote address.
-	type remoteNetAddr interface{ RemoteAddr() net.Addr }
 	type remoteStringAddr interface{ RemoteAddr() string }
-	if netra, ok := conn.(remoteNetAddr); ok {
-		codec.remoteAddr = netra.RemoteAddr().String()
-	} else if sra, ok := conn.(remoteStringAddr); ok {
-		codec.remoteAddr = sra.RemoteAddr()
+	type remoteNetAddr interface{ RemoteAddr() net.Addr }
+	if ra, ok := conn.(remoteStringAddr); ok {
+		codec.remoteAddr = ra.RemoteAddr()
+	} else if ra, ok := conn.(remoteNetAddr); ok {
+		codec.remoteAddr = ra.RemoteAddr().String()
 	}
 	return codec
 }

rpc/websocket.go

@@ -76,7 +76,18 @@ func newWebsocketCodec(conn *websocket.Conn) ServerCodec {
 	decoder := func(v interface{}) error {
 		return websocketJSONCodec.Receive(conn, v)
 	}
-	return NewCodec(conn, encoder, decoder)
+	rpcconn := Conn(conn)
+	if conn.IsServerConn() {
+		// Override remote address with the actual socket address because
+		// package websocket crashes if there is no request origin.
+		addr := conn.Request().RemoteAddr
+		if wsaddr := conn.RemoteAddr().(*websocket.Addr); wsaddr.URL != nil {
+			// Add origin if present.
+			addr += "(" + wsaddr.URL.String() + ")"
+		}
+		rpcconn = connWithRemoteAddr{conn, addr}
+	}
+	return NewCodec(rpcconn, encoder, decoder)
 }
 
 // NewWSServer creates a new websocket RPC server around an API provider.
@@ -113,9 +124,6 @@ func wsHandshakeValidator(allowedOrigins []string) func(*websocket.Config, *http
 	log.Debug(fmt.Sprintf("Allowed origin(s) for WS RPC interface %v", origins.ToSlice()))
 
 	f := func(cfg *websocket.Config, req *http.Request) error {
-		// Set config origin to the peer address to make RemoteAddr work.
-		cfg.Origin = &url.URL{Scheme: "ws", Host: req.RemoteAddr}
-
 		// Verify origin against whitelist.
 		origin := strings.ToLower(req.Header.Get("Origin"))
 		if allowAllOrigins || origins.Contains(origin) {