res_http_websocket.c: Continue reading after ping/pong

Do not return error if the client received ping frame
while looking for a string and just wait for another frame.

ASTERISK-28958 #close

Change-Id: I4d06b4827bd71e56cbaafc011ffdcef9f0332922

res/res_http_websocket.c

@@ -1434,6 +1434,12 @@ int AST_OPTIONAL_API_NAME(ast_websocket_read_string)
 			return -1;
 		}
 
+		if (opcode == AST_WEBSOCKET_OPCODE_PING) {
+			/* Try read again, we have sent pong already */
+			fragmented = 1;
+			continue;
+		}
+
 		if (opcode == AST_WEBSOCKET_OPCODE_CONTINUATION) {
 			continue;
 		}