Add rtcCreateOffer() and rtcCreateAnswer()

Author: paullouisageneau

DOC.md

@@ -207,7 +207,9 @@ Initiates the handshake process. Following this call, the local description call
 Arguments:
 
 - `pc`: the Peer Connection identifier
-- `type` (optional): type of the description ("offer", "answer", "pranswer", or "rollback") or NULL for autodetection.
+- `type` (optional): type of the description ("offer", "answer", "pranswer", or "rollback") or NULL for automatic (recommended).
+
+Warning: This function expects the optional type for the local description and not an SDP description. It is not possible to set an existing SDP description.
 
 #### rtcSetRemoteDescription
 
@@ -220,7 +222,7 @@ Sets the remote description received from the remote peer by the user's method o
 Arguments:
 
 - `pc`: the Peer Connection identifier
-- `type` (optional): type of the description ("offer", "answer", "pranswer", or "rollback") or NULL for autodetection.
+- `type` (optional): type of the description ("offer", "answer", "pranswer", or "rollback") or NULL for automatic (not recommended).
 
 If the remote description is an offer and `disableAutoNegotiation` was not set in `rtcConfiguration`, the library will automatically answer by calling `rtcSetLocalDescription` internally. Otherwise, the user must call it to answer the remote description.
 

include/rtc/rtc.h

@@ -211,7 +211,7 @@ RTC_C_EXPORT int rtcSetIceStateChangeCallback(int pc, rtcIceStateChangeCallbackF
 RTC_C_EXPORT int rtcSetGatheringStateChangeCallback(int pc, rtcGatheringStateCallbackFunc cb);
 RTC_C_EXPORT int rtcSetSignalingStateChangeCallback(int pc, rtcSignalingStateCallbackFunc cb);
 
-RTC_C_EXPORT int rtcSetLocalDescription(int pc, const char *type);
+RTC_C_EXPORT int rtcSetLocalDescription(int pc, const char *type); // type may be NULL
 RTC_C_EXPORT int rtcSetRemoteDescription(int pc, const char *sdp, const char *type);
 RTC_C_EXPORT int rtcAddRemoteCandidate(int pc, const char *cand, const char *mid);
 
@@ -221,6 +221,10 @@ RTC_C_EXPORT int rtcGetRemoteDescription(int pc, char *buffer, int size);
 RTC_C_EXPORT int rtcGetLocalDescriptionType(int pc, char *buffer, int size);
 RTC_C_EXPORT int rtcGetRemoteDescriptionType(int pc, char *buffer, int size);
 
+// For specific use cases only
+RTC_C_EXPORT int rtcCreateOffer(int pc, char *buffer, int size);
+RTC_C_EXPORT int rtcCreateAnswer(int pc, char *buffer, int size);
+
 RTC_C_EXPORT int rtcGetLocalAddress(int pc, char *buffer, int size);
 RTC_C_EXPORT int rtcGetRemoteAddress(int pc, char *buffer, int size);
 

src/capi.cpp

@@ -631,6 +631,24 @@ int rtcGetRemoteDescriptionType(int pc, char *buffer, int size) {
 	});
 }
 
+int rtcCreateOffer(int pc, char *buffer, int size) {
+	return wrap([&] {
+		auto peerConnection = getPeerConnection(pc);
+
+		auto desc = peerConnection->createOffer();
+		return copyAndReturn(string(desc), buffer, size);
+	});
+}
+
+int rtcCreateAnswer(int pc, char *buffer, int size) {
+	return wrap([&] {
+		auto peerConnection = getPeerConnection(pc);
+
+		auto desc = peerConnection->createAnswer();
+		return copyAndReturn(string(desc), buffer, size);
+	});
+}
+
 int rtcGetLocalAddress(int pc, char *buffer, int size) {
 	return wrap([&] {
 		auto peerConnection = getPeerConnection(pc);