Completed the functionalities of SrtpTransport.

webrtc/pc/channel.h

Index: webrtc/pc/channel.h
diff --git a/webrtc/pc/channel.h b/webrtc/pc/channel.h
index c6dc29dd08c9a1829f5b1b63f98d20bad28038bf..4b0f64d8cf2d1efbf6d3cbe8ddfc608484241814 100644
--- a/webrtc/pc/channel.h
+++ b/webrtc/pc/channel.h
@@ -33,7 +33,6 @@
 #include "webrtc/pc/mediamonitor.h"
 #include "webrtc/pc/mediasession.h"
 #include "webrtc/pc/rtcpmuxfilter.h"
-#include "webrtc/pc/rtptransportinternal.h"
 #include "webrtc/pc/srtpfilter.h"
 #include "webrtc/rtc_base/asyncinvoker.h"
 #include "webrtc/rtc_base/asyncudpsocket.h"
@@ -44,6 +43,8 @@
 
 namespace webrtc {
 class AudioSinkInterface;
+class RtpTransportInternal;
+class SrtpTransport;
 }  // namespace webrtc
 
 namespace cricket {
@@ -100,11 +101,13 @@ class BaseChannel
   bool enabled() const { return enabled_; }
 
   // This function returns true if we are using SRTP.

[Taylor Brandstetter, 2017/08/26 02:40:39]

nit: Should update this comment.

[Zhi Huang, 2017/08/29 18:40:34]

Done.

-  bool secure() const { return srtp_filter_.IsActive(); }
+  bool secure_sdes() const { return srtp_filter_.IsActive(); }

[pthatcher, 2017/08/28 21:42:56]

While we're changing the method name, can we make it something more
understandable, like "sdes_active" (and the other "dtls_active")?

[Zhi Huang, 2017/08/29 18:40:34]

Done.

   // The following function returns true if we are using
   // DTLS-based keying. If you turned off SRTP later, however
   // you could have secure() == false and dtls_secure() == true.
-  bool secure_dtls() const { return dtls_keyed_; }
+  bool secure_dtls() const { return dtls_active_; }
+
+  bool secure() const { return secure_sdes() || secure_dtls(); }

[pthatcher, 2017/08/28 21:42:56]

Would "srtp_active" be a good name here, to along with the others?

[Zhi Huang, 2017/08/29 18:40:34]

It sounds good to me.

 
   bool writable() const { return writable_; }
 
@@ -398,6 +401,7 @@ class BaseChannel
   DtlsTransportInternal* rtp_dtls_transport_ = nullptr;
   DtlsTransportInternal* rtcp_dtls_transport_ = nullptr;
   std::unique_ptr<webrtc::RtpTransportInternal> rtp_transport_;
+  webrtc::SrtpTransport* srtp_transport_ = nullptr;
   std::vector<std::pair<rtc::Socket::Option, int> > socket_options_;
   std::vector<std::pair<rtc::Socket::Option, int> > rtcp_socket_options_;
   SrtpFilter srtp_filter_;

[pthatcher, 2017/08/28 21:42:56]

It feels like this really should be renamed to SdesX sdes_x_.  What should the x
be?  Hmmm... maybe SdesSession or SdesNegotiation.  But it's not a filter any
more, and it's SDES-specific, not just any SRTP.

[Zhi Huang, 2017/08/29 18:40:34]

What about sdes_negotiator_? I plan to rename the class and files in a separate
CL since it would affect internal projects.

@@ -405,9 +409,8 @@ class BaseChannel
   bool writable_ = false;
   bool was_ever_writable_ = false;
   bool has_received_packet_ = false;
-  bool dtls_keyed_ = false;
+  bool dtls_active_ = false;
   const bool srtp_required_ = true;
-  int rtp_abs_sendtime_extn_id_ = -1;
 
   // MediaChannel related members that should be accessed from the worker
   // thread.