Update error handling and logging in message processing

- Modified the HandleMessage function to avoid logging actual message content and instead send generic error notices to clients for invalid or malformed messages, enhancing security by preventing exposure of binary data.
- Updated the NostrEscape function to escape all control characters to ensure valid JSON, preventing parsing errors with binary data.
- Adjusted policy checks to handle hex-encoded pubkeys correctly, ensuring compatibility with the updated encoding scheme.
- Introduced blackout period for relay connections after exceeding maximum reconnection delays, improving connection stability and management.

app/handle-message.go

@@ -75,9 +75,9 @@ func (l *Listener) HandleMessage(msg []byte, remote string) {
 	// Validate message for invalid characters before processing
 	if err := validateJSONMessage(msg); err != nil {
 		log.E.F("%s message validation FAILED (len=%d): %v", remote, len(msg), err)
-		log.T.F("%s invalid message content: %q", remote, msgPreview)
-		// Send error notice to client
-		if noticeErr := noticeenvelope.NewFrom("invalid message format: " + err.Error()).Write(l); noticeErr != nil {
+		// Don't log the actual message content as it contains binary data
+		// Send generic error notice to client
+		if noticeErr := noticeenvelope.NewFrom("invalid message format: contains invalid characters").Write(l); noticeErr != nil {
 			log.E.F("%s failed to send validation error notice: %v", remote, noticeErr)
 		}
 		return
@@ -94,10 +94,10 @@ func (l *Listener) HandleMessage(msg []byte, remote string) {
 			"%s envelope identification FAILED (len=%d): %v", remote, len(msg),
 			err,
 		)
-		log.T.F("%s malformed message content: %q", remote, msgPreview)
+		// Don't log message preview as it may contain binary data
 		chk.E(err)
 		// Send error notice to client
-		if noticeErr := noticeenvelope.NewFrom("malformed message: " + err.Error()).Write(l); noticeErr != nil {
+		if noticeErr := noticeenvelope.NewFrom("malformed message").Write(l); noticeErr != nil {
 			log.E.F(
 				"%s failed to send malformed message notice: %v", remote,
 				noticeErr,
@@ -132,18 +132,18 @@ func (l *Listener) HandleMessage(msg []byte, remote string) {
 	default:
 		err = fmt.Errorf("unknown envelope type %s", t)
 		log.E.F(
-			"%s unknown envelope type: %s (payload: %q)", remote, t,
-			string(rem),
+			"%s unknown envelope type: %s (payload_len: %d)", remote, t,
+			len(rem),
 		)
 	}
 
 	// Handle any processing errors
 	if err != nil {
 		log.E.F("%s message processing FAILED (type=%s): %v", remote, t, err)
-		log.T.F("%s error context - original message: %q", remote, msgPreview)
+		// Don't log message preview as it may contain binary data
 
-		// Send error notice to client
-		noticeMsg := fmt.Sprintf("%s: %s", t, err.Error())
+		// Send error notice to client (use generic message to avoid control chars in errors)
+		noticeMsg := fmt.Sprintf("%s processing failed", t)
 		if noticeErr := noticeenvelope.NewFrom(noticeMsg).Write(l); noticeErr != nil {
 			log.E.F(
 				"%s failed to send error notice after %s processing failure: %v",