Improve testing of SRTP external auth code paths.

webrtc/pc/srtpfilter.h

Index: webrtc/pc/srtpfilter.h
diff --git a/webrtc/pc/srtpfilter.h b/webrtc/pc/srtpfilter.h
index 46b9dea19f38400abdb38f56cabc2eeece1197fb..3412ac4dfaf05b698fadcf6ad880ea1ca404698e 100644
--- a/webrtc/pc/srtpfilter.h
+++ b/webrtc/pc/srtpfilter.h
@@ -114,12 +114,16 @@ class SrtpFilter {
   // Returns srtp overhead for rtp packets.
   bool GetSrtpOverhead(int* srtp_overhead) const;
 
-#if defined(ENABLE_EXTERNAL_AUTH)
+  void AllowExternalAuthForTest(bool allow);
+
+  // External auth is only allowed if ENABLE_EXTERNAL_AUTH is defined or
+  // it has been explicitly activated for tests.

[Taylor Brandstetter, 2017/03/03 02:20:34]

Is there any comment in general explaining what external auth is? If not it
would be nice, in case someone encounters this code without context.

[joachim, 2017/03/03 20:42:57]

There is a comment in channel.cc (BaseChannel::SendPacket) where the code is
different depending on whether external auth is active.

Added another comment here.

+  bool IsExternalAuthAllowed() const;
+
   // A SRTP filter supports external creation of the auth tag if a non-GCM
   // cipher is used. This method is only valid after the RTP params have
   // been set.
   bool IsExternalAuthActive() const;
-#endif
 
   // Update the silent threshold (in ms) for signaling errors.
   void set_signal_silent_time(int signal_silent_time_in_ms);
@@ -169,8 +173,9 @@ class SrtpFilter {
     // ST_INIT.
     ST_RECEIVEDPRANSWER
   };
-  State state_;
-  int signal_silent_time_in_ms_;
+  State state_ = ST_INIT;
+  int signal_silent_time_in_ms_ = 0;
+  bool external_auth_allowed_ = false;
   std::vector<CryptoParams> offer_params_;
   std::unique_ptr<SrtpSession> send_session_;
   std::unique_ptr<SrtpSession> recv_session_;
@@ -213,12 +218,16 @@ class SrtpSession {
 
   int GetSrtpOverhead() const;
 
-#if defined(ENABLE_EXTERNAL_AUTH)
+  void AllowExternalAuthForTest(bool allow);
+
+  // External auth is only allowed if ENABLE_EXTERNAL_AUTH is defined or
+  // it has been explicitly activated for tests.
+  bool IsExternalAuthAllowed() const;
+
   // A SRTP session supports external creation of the auth tag if a non-GCM
   // cipher is used. This method is only valid after the RTP params have
   // been set.
   bool IsExternalAuthActive() const;
-#endif
 
   // Update the silent threshold (in ms) for signaling errors.
   void set_signal_silent_time(int signal_silent_time_in_ms);
@@ -246,9 +255,8 @@ class SrtpSession {
   static bool inited_;
   static rtc::GlobalLockPod lock_;
   int last_send_seq_num_ = -1;
-#if defined(ENABLE_EXTERNAL_AUTH)
   bool external_auth_active_ = false;
-#endif
+  bool external_auth_allowed_ = false;
   RTC_DISALLOW_COPY_AND_ASSIGN(SrtpSession);
 };