Add datachannel c apis and callbacks(#3328)

增加datachannel数据收发的回调通知 #3326，和控制datachannel回显的开关

---------

Co-authored-by: xiongziliang <771730766@qq.com>

api/source/mk_events_objects.cpp

@@ -17,6 +17,7 @@
 
 #include "Http/HttpClient.h"
 #include "Rtsp/RtspSession.h"
+#include "webrtc/WebRtcTransport.h"
 
 using namespace toolkit;
 using namespace mediakit;
@@ -497,4 +498,22 @@ API_EXPORT void API_CALL mk_auth_invoker_clone_release(const mk_auth_invoker ctx
     assert(ctx);
     Broadcast::AuthInvoker *invoker = (Broadcast::AuthInvoker *)ctx;
     delete invoker;
-}
+}
+
+///////////////////////////////////////////WebRtcTransport/////////////////////////////////////////////
+API_EXPORT void API_CALL mk_rtc_sendDatachannel(const mk_rtc_transport ctx, uint16_t streamId, uint32_t ppid, const char *msg, size_t len) {
+#ifdef ENABLE_WEBRTC
+    assert(ctx && msg);
+    WebRtcTransport *transport = (WebRtcTransport *)ctx;
+    std::string msg_str(msg, len);
+    std::weak_ptr<WebRtcTransport> weak_trans = transport->shared_from_this();
+    transport->getPoller()->async([streamId, ppid, msg_str, weak_trans]() {
+        // 切换线程后再操作
+        if (auto trans = weak_trans.lock()) {
+            trans->sendDatachannel(streamId, ppid, msg_str.c_str(), msg_str.size());
+        }
+    });
+#else
+    WarnL << "未启用webrtc功能, 编译时请开启ENABLE_WEBRTC";
+#endif
+}