p2p: wrap internal error in new error type

Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>

Author: cskiraly

p2p/metrics.go

@@ -68,6 +68,7 @@ func markDialError(err error) {
 		return
 	}
 
+	var e *protoHandshakeError
 	switch {
 	case errors.Is(err, DiscTooManyPeers):
 		dialTooManyPeers.Mark(1)
@@ -81,7 +82,7 @@ func markDialError(err error) {
 		dialUnexpectedIdentity.Mark(1)
 	case errors.Is(err, errEncHandshakeError):
 		dialEncHandshakeError.Mark(1)
-	case errors.Is(err, errProtoHandshakeError):
+	case errors.As(err, &e):
 		dialProtoHandshakeError.Mark(1)
 	}
 }

p2p/server.go

@@ -66,11 +66,15 @@ const (
 )
 
 var (
-	errServerStopped       = errors.New("server stopped")
-	errEncHandshakeError   = errors.New("rlpx enc error")
-	errProtoHandshakeError = errors.New("rlpx proto error")
+	errServerStopped     = errors.New("server stopped")
+	errEncHandshakeError = errors.New("rlpx enc error")
 )
 
+type protoHandshakeError struct{ err error }
+
+func (e *protoHandshakeError) Error() string { return fmt.Sprintf("rlpx proto error: %s", e.err) }
+func (e *protoHandshakeError) Unwrap() error { return e.err }
+
 // Server manages all peer connections.
 type Server struct {
 	// Config fields may not be modified while the server is running.
@@ -908,7 +912,7 @@ func (srv *Server) setupConn(c *conn, dialDest *enode.Node) error {
 	if err != nil {
 		clog.Trace("Failed p2p handshake", "err", err)
 		//Wrapping both errors for later inspection
-		return fmt.Errorf("%w: %w", errProtoHandshakeError, err)
+		return &protoHandshakeError{err: err}
 	}
 	if id := c.node.ID(); !bytes.Equal(crypto.Keccak256(phs.ID), id[:]) {
 		clog.Trace("Wrong devp2p handshake identity", "phsid", hex.EncodeToString(phs.ID))