unmask() — netty Function Reference

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocket08FrameDecoder.java lines 392–424

    private void unmask(ByteBuf frame) {
        int i = frame.readerIndex();
        int end = frame.writerIndex();

        ByteOrder order = frame.order();

        int intMask = mask;
        if (intMask == 0) {
            // If the mask is 0 we can just return directly as the XOR operations will just produce the same value.
            return;
        }
        // Avoid sign extension on widening primitive conversion
        long longMask = intMask & 0xFFFFFFFFL;
        longMask |= longMask << 32;

        for (int lim = end - 7; i < lim; i += 8) {
            frame.setLong(i, frame.getLong(i) ^ longMask);
        }

        if (i < end - 3) {
            frame.setInt(i, frame.getInt(i) ^ (int) longMask);
            i += 4;
        }

        if (order == ByteOrder.LITTLE_ENDIAN) {
            intMask = Integer.reverseBytes(intMask);
        }

        int maskOffset = 0;
        for (; i < end; i++) {
            frame.setByte(i, frame.getByte(i) ^ WebSocketUtil.byteAtIndex(intMask, maskOffset++ & 3));
        }
    }