Added max burst setting for SCTP

include/rtc/global.hpp

@@ -46,10 +46,12 @@ RTC_EXPORT void Preload();
 RTC_EXPORT void Cleanup();
 
 struct SctpSettings {
+	// For the following settings, not set means optimized default
 	optional<size_t> recvBufferSize;
 	optional<size_t> sendBufferSize;
 	optional<size_t> maxChunksOnQueue;
 	optional<size_t> initialCongestionWindow;
+	optional<size_t> maxBurst;
 	optional<unsigned int> congestionControlModule;
 	optional<std::chrono::milliseconds> delayedSackTime;
 };

include/rtc/rtc.h

@@ -226,6 +226,7 @@ typedef struct {
 	int sendBufferSize;          // <= 0 means optimized default
 	int maxChunksOnQueue;        // <= 0 means optimized default
 	int initialCongestionWindow; // <= 0 means optimized default
+	int maxBurst;				 // 0 means optimized default, < 0 means disabled
 	int congestionControlModule; // <= 0 means default (0: RFC2581, 1: HSTCP, 2: H-TCP, 3: RTCC)
 	int delayedSackTimeMs;       // <= 0 means optimized default
 } rtcSctpSettings;

src/capi.cpp

@@ -683,6 +683,11 @@ int rtcSetSctpSettings(const rtcSctpSettings *settings) {
 		if (settings->initialCongestionWindow > 0)
 			s.initialCongestionWindow = size_t(settings->initialCongestionWindow);
 
+		if (settings->maxBurst > 0)
+			s.maxBurst = size_t(settings->maxBurst);
+		else if (settings->maxBurst < 0)
+			s.maxBurst = size_t(0); // setting to 0 disables, not setting chooses optimized default
+
 		if (settings->congestionControlModule >= 0)
 			s.congestionControlModule = unsigned(settings->congestionControlModule);
 

src/impl/sctptransport.cpp

@@ -115,6 +115,9 @@ void SctpTransport::SetSettings(const SctpSettings &s) {
 	// Increase initial congestion window size to 10 MTUs (RFC 6928) by default
 	usrsctp_sysctl_set_sctp_initial_cwnd(to_uint32(s.initialCongestionWindow.value_or(10)));
 
+	// Set max burst to 10 MTUs by default (max burst is initially 0, meaning disabled)
+	usrsctp_sysctl_set_sctp_max_burst_default(to_uint32(s.maxBurst.value_or(10)));
+
 	// Use standard SCTP congestion control (RFC 4960) by default
 	// See https://github.com/paullouisageneau/libdatachannel/issues/354
 	usrsctp_sysctl_set_sctp_default_cc_module(to_uint32(s.congestionControlModule.value_or(0)));