Support for Signal calls.

Merge in RedPhone

// FREEBIE

jni/redphone/RtpAudioReceiver.cpp

@@ -0,0 +1,38 @@
+#include "RtpAudioReceiver.h"
+
+#include <android/log.h>
+
+#define TAG "RtpAudioReceiver"
+
+RtpAudioReceiver::RtpAudioReceiver(int socketFd, SrtpStreamParameters *parameters) :
+  socketFd(socketFd), sequenceCounter(), srtpStream(parameters)
+{
+}
+
+int RtpAudioReceiver::init() {
+  if (srtpStream.init() != 0) {
+    __android_log_print(ANDROID_LOG_WARN, TAG, "SRTP stream failed to initialize!");
+    return -1;
+  }
+
+  return 0;
+}
+
+RtpPacket* RtpAudioReceiver::receive(char* encodedData, int encodedDataLen) {
+  int received = recv(socketFd, encodedData, encodedDataLen, 0);
+
+  if (received == -1) {
+    __android_log_print(ANDROID_LOG_WARN, TAG, "recv() failed!");
+    return NULL;
+  }
+
+  RtpPacket *packet = new RtpPacket(encodedData, received);
+
+  if (srtpStream.decrypt(*packet, sequenceCounter.convertNext(packet->getSequenceNumber())) != 0) {
+    __android_log_print(ANDROID_LOG_WARN, TAG, "SRTP decrypt failed!");
+    delete packet;
+    return NULL;
+  }
+
+  return packet;
+}