- improve SRTP decoder API

src/engine/media/MT_AudioStream.cpp

@@ -306,18 +306,22 @@ void AudioStream::dataArrived(PDatagramSocket s, const void* buffer, int length,
     int receiveLength = length;
     memcpy(mReceiveBuffer, buffer, length);
 
-    bool srtpResult;
     if (mSrtpSession.active())
     {
+        bool srtpResult;
+        size_t srcLength = length; size_t dstLength = sizeof mSrtpDecodeBuffer;
         if (RtpHelper::isRtp(mReceiveBuffer, receiveLength))
-            srtpResult = mSrtpSession.unprotectRtp(mReceiveBuffer, &receiveLength);
+            srtpResult = mSrtpSession.unprotectRtp(mReceiveBuffer, srcLength, mSrtpDecodeBuffer, &dstLength);
         else
-            srtpResult = mSrtpSession.unprotectRtcp(mReceiveBuffer, &receiveLength);
+            srtpResult = mSrtpSession.unprotectRtcp(mReceiveBuffer, srcLength, mSrtpDecodeBuffer, &dstLength);
         if (!srtpResult)
         {
             ICELogError(<<"Cannot decrypt SRTP packet.");
             return;
         }
+
+        memcpy(mReceiveBuffer, mSrtpDecodeBuffer, dstLength);
+        receiveLength = dstLength;
     }
 
     switch (source.family())

src/engine/media/MT_AudioStream.h

@@ -87,7 +87,8 @@ protected:
     mCaptureResampler32,
     mCaptureResampler48;
     DtmfContext mDtmfContext;
-    char mReceiveBuffer[MAX_VALID_UDPPACKET_SIZE];
+    char mReceiveBuffer[MAX_VALID_UDPPACKET_SIZE],
+         mSrtpDecodeBuffer[MAX_VALID_UDPPACKET_SIZE];
 
     struct
     {

src/engine/media/MT_SrtpHelper.cpp

@@ -209,36 +209,32 @@ bool SrtpSession::protectRtcp(void* buffer, int* length)
         return false;
 }
 
-bool SrtpSession::unprotectRtp(void* buffer, int* length)
+bool SrtpSession::unprotectRtp(const void* src, size_t srcLength, void* dst, size_t* dstLength)
 {
     //addSsrc(RtpHelper::findSsrc(buffer, *length), sdIncoming);
 
     Lock l(mGuard);
     if (mInboundSession)
     {
-        size_t rtp_len = MAX_VALID_UDPPACKET_SIZE;
         auto code = srtp_unprotect(mInboundSession,
-                                    (const uint8_t*)buffer, (size_t)*length,
-                                    (uint8_t*)buffer, &rtp_len);
-        *length = rtp_len;
+                                   (const uint8_t*)src, srcLength,
+                                   (uint8_t*)dst, dstLength);
         return code == 0;
     }
     else
         return false;
 }
 
-bool SrtpSession::unprotectRtcp(void* buffer, int* length)
+bool SrtpSession::unprotectRtcp(const void* src, size_t srcLength, void* dst, size_t* dstLength)
 {
     //addSsrc(RtpHelper::findSsrc(buffer, *length), sdIncoming);
 
     Lock l(mGuard);
     if (mInboundSession)
     {
-        size_t rtp_len = MAX_VALID_UDPPACKET_SIZE;
         auto code = srtp_unprotect_rtcp(mInboundSession,
-                                        (const uint8_t*)buffer, (size_t)*length,
-                                        (uint8_t*)buffer, (size_t*)rtp_len);
-        *length = rtp_len;
+                                        (const uint8_t*)src, srcLength,
+                                        (uint8_t*)dst, dstLength);
         return code == 0;
     }
     else

src/engine/media/MT_SrtpHelper.h

@@ -48,8 +48,8 @@ public:
   /* bufferPtr is RTP packet data i.e. header + payload. Buffer must be big enough to hold encrypted data. */
   bool protectRtp(void* buffer, int* length);
   bool protectRtcp(void* buffer, int* length);
-  bool unprotectRtp(void* buffer, int* length);
-  bool unprotectRtcp(void* buffer, int* length);
+  bool unprotectRtp(const void* src, size_t srcLength, void* dst, size_t* dstLength);
+  bool unprotectRtcp(const void* src, size_t srcLength, void* dst, size_t* dstLength);
   
 
   static void initSrtp();