Support GCM ciphers even if ENABLE_EXTERNAL_AUTH is defined.

webrtc/pc/srtpfilter.h

Index: webrtc/pc/srtpfilter.h
diff --git a/webrtc/pc/srtpfilter.h b/webrtc/pc/srtpfilter.h
index 06edddf80d97a4e6d1a8274c4710cb94c11fc4a6..a4605ed9eac0118f263f5cea1511598a67590fb3 100644
--- a/webrtc/pc/srtpfilter.h
+++ b/webrtc/pc/srtpfilter.h
@@ -108,6 +108,15 @@ class SrtpFilter {
   bool UnprotectRtp(void* data, int in_len, int* out_len);
   bool UnprotectRtcp(void* data, int in_len, int* out_len);
 
+  // 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 AllowExternalAuth();
+
+  // Force-disable support for external auth tag creation. This is required
+  // for some tests.
+  void DisableAllowExternalAuthForTests(bool disable_allow_external_auth);
+
   // Returns rtp auth params from srtp context.
   bool GetRtpAuthParams(uint8_t** key, int* key_len, int* tag_len);
 
@@ -164,6 +173,7 @@ class SrtpFilter {
   };
   State state_;
   int signal_silent_time_in_ms_;
+  bool force_disable_allow_external_auth_ = false;
   std::vector<CryptoParams> offer_params_;
   std::unique_ptr<SrtpSession> send_session_;
   std::unique_ptr<SrtpSession> recv_session_;
@@ -201,6 +211,10 @@ class SrtpSession {
   bool UnprotectRtp(void* data, int in_len, int* out_len);
   bool UnprotectRtcp(void* data, int in_len, int* out_len);
 
+  bool AllowExternalAuth();
+
+  void DisableAllowExternalAuthForTests(bool disable_allow_external_auth);
+
   // Helper method to get authentication params.
   bool GetRtpAuthParams(uint8_t** key, int* key_len, int* tag_len);
 
@@ -225,13 +239,15 @@ class SrtpSession {
   static void HandleEventThunk(srtp_event_data_t* ev);
 
   rtc::ThreadChecker thread_checker_;
-  srtp_ctx_t_* session_;
-  int rtp_auth_tag_len_;
-  int rtcp_auth_tag_len_;
+  srtp_ctx_t_* session_ = nullptr;
+  int rtp_auth_tag_len_ = 0;
+  int rtcp_auth_tag_len_ = 0;
   std::unique_ptr<SrtpStat> srtp_stat_;
   static bool inited_;
   static rtc::GlobalLockPod lock_;
-  int last_send_seq_num_;
+  int last_send_seq_num_ = -1;
+  bool allow_external_auth_ = false;
+  bool force_disable_allow_external_auth_ = false;
   RTC_DISALLOW_COPY_AND_ASSIGN(SrtpSession);
 };