Media/WebRTC/SIPCCMessaging

Notes on how to add a new message to SIPCC

SIPCC uses a bunch of message queues so it can be complicated to figure out how to add a new subroutine call at the CC API layer and have it make it all the way to the GSM layer. The following is just a checklist of the things you will have to change.

• Add the new API to the abstract CC_Call interface in: media/webrtc/signaling/include/CC_Call.h.

 virtual void setPeerConnection(const std::string& handle) = 0;

• Add the new API to the the concrete CC_SIPCall implementation in: media/webrtc/signaling/src/softphonewrapper/CC_SIPCCCall.h:

       virtual void setPeerConnection(const std::string& handle);

• And media/webrtc/signaling/src/softphonewrapper/CC_SIPCCCall.cpp. Note that this is just calling a wrapper and this is where the C++/C transition takes place:

 void CC_SIPCCCall::setPeerConnection(const std::string& handle)
 {
   CSFLogDebug(logTag, "setPeerConnection");
   peerconnection = handle;
   CCAPI_SetPeerConnection(callHandle, handle.c_str());
 }

• Add the new CCAPI_* wrapper to: media/webrtc/signaling/src/sipcc/include/ccapi_call.h

 cc_return_t CCAPI_SetPeerConnection(cc_call_handle_t handle, cc_peerconnection_t pc);

• The implementation goes in: media/webrtc/signaling/src/sipcc/core/ccapp/ccapi_call.c. In this case this is a wrapper around a feature set:

 cc_return_t CCAPI_SetPeerConnection(cc_call_handle_t handle, cc_peerconnection_t pc) {
   return CC_CallFeature_SetPeerConnection(handle, pc);
 }

• We need a new feature name. Set it up in: media/webrtc/signaling/src/sipcc/core/includes/ccapi.h in group_cc_feature_t.

 CC_FEATURE_SETPEERCONNECTION

• Also add it to the list in: media/webrtc/signaling/src/sipcc/core/includes/ccapi.h in cc_feature_names[]

 "SETPEERCONNECTION",  

• In the same file add in cc_msg_t

 CC_MSG_SETPEERCONNECTION,

• and in cc_msg_names

 "SETPEERCONNECTION",

• Implement the feature send which is a wrapper around a CPR send. The declaration goes in: media/webrtc/signaling/src/sipcc/include/cc_call_feature.h

 cc_return_t CC_CallFeature_SetPeerConnection(cc_call_handle_t call_handle, cc_peerconnection_t pc);

• The implementation goes in media/webrtc/signaling/src/sipcc/core/ccapp/cc_call_feature.c. Note that we have defined a CC_FEATURE_SETPEERCONNECTION. The net effect of this is to send a msg across the message queue.

 cc_return_t CC_CallFeature_SetPeerConnection(cc_call_handle_t call_handle, cc_peerconnection_t pc) {
     cc_media_constraints_t *constraints = NULL;
     CCAPP_DEBUG(DEB_L_C_F_PREFIX, DEB_L_C_F_PREFIX_ARGS(SIP_CC_PROV, GET_CALL_ID(call_handle),
                 GET_LINE_ID(call_handle), __FUNCTION__));
 
     return cc_invokeFeatureSDPMode(call_handle, CC_FEATURE_SETPEERCONNECTION, JSEP_NO_ACTION,
                                    0, 0, NO_STREAM, 0, constraints, pc, NULL);
 }

• On the other end of the message queue (in ccapp), we need to handle the event. We add new code to: media/webrtc/signaling/src/sipcc/core/ccapp/ccprovider.c in processSessionEvent:

        case CC_FEATURE_SETPEERCONNECTION:
          PR_ASSERT(strlen(data) < PC_HANDLE_SIZE);
          if (strlen(data) >= PC_HANDLE_SIZE)
            return;
 
          sstrncpy(featdata.pc.pc_handle, data, sizeof(featdata.pc.pc_handle));
 
          cc_int_feature2(CC_MSG_SETPEERCONNECTION, CC_SRC_UI, CC_SRC_GSM,
            call_id, (line_t)instance,
            CC_FEATURE_SETPEERCONNECTION, &featdata);
          break;

File: media/webrtc/signaling/src/softphonewrapper/CC_SIPCCCall.cpp

 int CC_SIPCCCall::createOffer (MediaTrackTable* tracks, const std::string& hints) {
     return CCAPI_CreateOffer(callHandle, tracks, 16384, 1024);
 }

File: media/webrtc/signaling/src/sipcc/core/ccapp/ccapi_call.c

 cc_return_t CCAPI_CreateOffer(cc_call_handle_t handle, MediaTrackTable* tracks, int audioPort, int videoPort)

File: media/webrtc/signaling/src/sipcc/core/ccapp/cc_call_feature.c

 cc_return_t CC_CallFeature_CreateOffer(cc_call_handle_t call_handle, cc_sdp_direction_t video_pref)

File: media/webrtc/signaling/src/sipcc/core/ccapp/cc_call_feature.c

 cc_return_t cc_invokeFeature(cc_call_handle_t call_handle, group_cc_feature_t featureId, cc_sdp_direction_t video_pref, cc_jsep_action_t action, string_t data)

ccappTaskPostMsg  ====>  ccapp message queue

src/sipcc/core/ccapp/ccprovider.c  
  processSessionEvent (line_t line_id, callid_t call_id, unsigned int event, sdp_direction_e video_pref, ccSession_feature_t ccData)

src/sipcc/core/gsm/ccapi.c
  void cc_createoffer (cc_srcs_t src_id, cc_srcs_t dst_id, callid_t call_id, line_t line, cc_features_t feature_id, cc_feature_data_t *data)


cc_send_msg ====> gsm message queue

src/sipcc/core/gsm/fim.c
  boolean fim_process_event (void *data, boolean cac_passed)

src/sipcc/core/gsm/fsmdef.c
  static sm_rcs_t fsmdef_ev_createoffer (sm_event_t *event)