for #730, refine code to decode the acknowledge message

@@ -5017,6 +5017,22 @@ SrsAcknowledgementPacket::~SrsAcknowledgementPacket()
 {
 }
 
+int SrsAcknowledgementPacket::decode(SrsBuffer* stream)
+{
+    int ret = ERROR_SUCCESS;
+    
+    if (!stream->require(4)) {
+        ret = ERROR_RTMP_MESSAGE_DECODE;
+        srs_error("decode acknowledgement failed. ret=%d", ret);
+        return ret;
+    }
+    
+    sequence_number = stream->read_4bytes();
+    srs_info("decode acknowledgement success");
+    
+    return ret;
+}
+
 int SrsAcknowledgementPacket::get_prefer_cid()
 {
     return RTMP_CID_ProtocolControl;

@@ -1847,6 +1847,9 @@ public:
 public:
     SrsAcknowledgementPacket();
     virtual ~SrsAcknowledgementPacket();
+// decode functions for concrete packet to override.
+public:
+    virtual int decode(SrsBuffer* stream);
 // encode functions for concrete packet to override.
 public:
     virtual int get_prefer_cid();

@@ -31,12 +31,12 @@ using namespace std;
 VOID TEST(CoreAutoFreeTest, Free)
 {
     char* data = new char[32];
-    srs_freep(data);
+    srs_freepa(data);
     EXPECT_TRUE(data == NULL);
 
     if (true) {
         data = new char[32];
-        SrsAutoFree(char, data);
+        SrsAutoFreeA(char, data);
     }
     EXPECT_TRUE(data == NULL);
 }