wifi: Clear ring bufffers on detecting buffer corruption

While appending the newly received buffer to ring buffer list,
check the size of the first buffer in the ring buffer list.
If it is invalid(zero size or exceeding the max allowed size),
return failure & clear all the ring buffers.

Bug: 232477451
Test: vts test - 1.6/default/tests/runtests.sh
Test: Manual - Ran basic wifi tests & checked bugreports

Change-Id: Iaa41262f534914b971fe178053f1974248a46e70
diff --git a/wifi/1.6/default/ringbuffer.h b/wifi/1.6/default/ringbuffer.h
index 8571a9f..c6a1e4c 100644
--- a/wifi/1.6/default/ringbuffer.h
+++ b/wifi/1.6/default/ringbuffer.h
@@ -31,11 +31,19 @@
  */
 class Ringbuffer {
   public:
+    // Error codes for the append ring buffer operation
+    enum AppendStatus {
+        SUCCESS,
+        FAIL_GENERIC,
+        FAIL_IP_BUFFER_ZERO,
+        FAIL_IP_BUFFER_EXCEEDED_MAXSIZE,
+        FAIL_RING_BUFFER_CORRUPTED
+    };
     explicit Ringbuffer(size_t maxSize);
 
     // Appends the data buffer and deletes from the front until buffer is
     // within |maxSize_|.
-    void append(const std::vector<uint8_t>& input);
+    enum AppendStatus append(const std::vector<uint8_t>& input);
     const std::list<std::vector<uint8_t>>& getData() const;
     void clear();