[core] Added assertions and error checks to CRcvBuffer

srtcore/buffer.cpp

@@ -676,9 +676,9 @@ void CSndBuffer::increase()
 //const int CRcvBuffer::TSBPD_DRIFT_PRT_SAMPLES = 200;   // ACK-ACK packets
 #endif
 
-CRcvBuffer::CRcvBuffer(CUnitQueue* queue, int bufsize):
+CRcvBuffer::CRcvBuffer(CUnitQueue* queue, int bufsize_pkts):
 m_pUnit(NULL),
-m_iSize(bufsize),
+m_iSize(bufsize_pkts),
 m_pUnitQueue(queue),
 m_iStartPos(0),
 m_iLastAckPos(0),
@@ -760,7 +760,11 @@ void CRcvBuffer::countBytes(int pkts, int bytes, bool acked)
 
 int CRcvBuffer::addData(CUnit* unit, int offset)
 {
-   int pos = (m_iLastAckPos + offset) % m_iSize;
+   SRT_ASSERT(unit != NULL);
+   if (offset >= getAvailBufSize())
+       return -1;
+
+   const int pos = (m_iLastAckPos + offset) % m_iSize;
    if (offset >= m_iMaxPos)
       m_iMaxPos = offset + 1;
 
@@ -784,11 +788,17 @@ int CRcvBuffer::readBuffer(char* data, int len)
    char* begin = data;
 #endif
 
-   uint64_t now = (m_bTsbPdMode ? CTimer::getTime() : uint64_t());
+   const uint64_t now = (m_bTsbPdMode ? CTimer::getTime() : uint64_t());
 
    HLOGC(dlog.Debug, log << CONID() << "readBuffer: start=" << p << " lastack=" << lastack);
    while ((p != lastack) && (rs > 0))
    {
+       if (m_pUnit[p] == NULL)
+       {
+           LOGC(dlog.Error, log << CONID() << " IPE readBuffer on null packet pointer");
+           return -1;
+       }
+
       if (m_bTsbPdMode)
       {
           HLOGC(dlog.Debug, log << CONID() << "readBuffer: chk if time2play: NOW=" << now << " PKT TS=" << getPktTsbPdTime(m_pUnit[p]->m_Packet.getMsgTimeStamp()));
@@ -871,6 +881,9 @@ int CRcvBuffer::readBufferToFile(fstream& ofs, int len)
 
 void CRcvBuffer::ackData(int len)
 {
+   SRT_ASSERT(len < m_iSize);
+   SRT_ASSERT(len > 0);
+
    {
       int pkts = 0;
       int bytes = 0;

srtcore/buffer.h

@@ -239,7 +239,10 @@ class CRcvBuffer
     std::string CONID() const { return ""; }
 
 
-   CRcvBuffer(CUnitQueue* queue, int bufsize = 65536);
+      /// Construct the buffer.
+      /// @param [in] queue  CUnitQueue that actually holds the units (packets)
+      /// @param [in] bufsize_pkts in units (packets)
+   CRcvBuffer(CUnitQueue* queue, int bufsize_pkts = 65536);
    ~CRcvBuffer();
 
       /// Write data into the buffer.
@@ -270,7 +273,11 @@ class CRcvBuffer
    void ackData(int len);
 
       /// Query how many buffer space left for data receiving.
+      /// Actually only acknowledged packets, that are still in the buffer,
+      /// are considered to take buffer space.
+      ///
       /// @return size of available buffer space (including user buffer) for data receiving.
+      ///         Not counting unacknowledged packets.
 
    int getAvailBufSize() const;
 
@@ -419,7 +426,7 @@ class CRcvBuffer
 
 private:
    CUnit** m_pUnit;                     // pointer to the protocol buffer
-   int m_iSize;                         // size of the protocol buffer
+   int m_iSize;                         // size of the protocol buffer in units
    CUnitQueue* m_pUnitQueue;            // the shared unit queue
 
    int m_iStartPos;                     // the head position for I/O (inclusive)

srtcore/core.cpp

@@ -5223,7 +5223,7 @@ int CUDT::receiveBuffer(char* data, int len)
         throw CUDTException(MJ_CONNECTION, MN_CONNLOST, 0);
     }
 
-    int res = m_pRcvBuffer->readBuffer(data, len);
+    const int res = m_pRcvBuffer->readBuffer(data, len);
 
     /* Kick TsbPd thread to schedule next wakeup (if running) */
     if (m_bTsbPd)