Merge pull request #10416 from maribu/cc2420

drivers/cc2420: Implemented missing drop case

drivers/cc2420/cc2420.c

@@ -180,14 +180,21 @@ int cc2420_rx(cc2420_t *dev, uint8_t *buf, size_t max_len, void *info)
         cc2420_ram_read(dev, CC2420_RAM_RXFIFO, &len, 1);
         len -= 2;   /* subtract RSSI and FCF */
         DEBUG("cc2420: recv: packet of length %i in RX FIFO\n", (int)len);
+        if (max_len != 0) {
+            DEBUG("cc2420: recv: Dropping frame as requested\n");
+            _flush_rx_fifo(dev);
+        }
     }
     else {
         /* read length byte */
         cc2420_fifo_read(dev, &len, 1);
         len -= 2;   /* subtract RSSI and FCF */
 
-        /* if a buffer is given, read (and drop) the packet */
-        len = (len > max_len) ? max_len : len;
+        if (len > max_len) {
+            DEBUG("cc2420: recv: Supplied buffer to small\n");
+            _flush_rx_fifo(dev);
+            return -ENOBUFS;
+        }
 
         /* read fifo contents */
         DEBUG("cc2420: recv: reading %i byte of the packet\n", (int)len);