add random cap (1020-1220) and tighten cubic rate limit more

solanaceae/ngc_ft1/cubic.cpp

@@ -84,11 +84,15 @@ int64_t CUBIC::canSend(void) {
 
 	// also limit to max sendrate per tick, which is usually smaller than window
 	// this is mostly to prevent spikes on empty windows
+	const auto rate = window / getCurrentDelay();
+
 	// assuming at most 20ms tick interval
 	// TODO: pass down actual tick interval
-	const auto rate = window / getCurrentDelay();
+	//const float time_delta = 0.02f; // 20ms
+	const float time_delta = 0.01666f;
+
 	// we dont want this limit to fall below atleast 1 segment
-	const int64_t max_bytes_per_tick = std::max<int64_t>(rate * 0.02f + 0.5f, MAXIMUM_SEGMENT_SIZE);
+	const int64_t max_bytes_per_tick = std::max<int64_t>(rate * time_delta + 0.5f, MAXIMUM_SEGMENT_SIZE);
 	cspace_bytes = std::min<int64_t>(cspace_bytes, max_bytes_per_tick);
 
 	// limit to whole packets

solanaceae/ngc_ft1/ngcft1.cpp

@@ -4,6 +4,7 @@
 #include "./cubic.hpp"
 #include "./ledbat.hpp"
 
+#include <cstdint>
 #include <solanaceae/toxcore/utils.hpp>
 
 #include <sodium.h>
@@ -513,7 +514,14 @@ bool NGCFT1::onEvent(const Events::NGCEXT_ft1_init_ack& e) {
 	const auto negotiated_packet_data_size = std::min<uint32_t>(e.max_lossy_data_size, _t.toxGroupMaxCustomLossyPacketLength()-4);
 	// TODO: reset cca with new pkg size
 	if (!peer.cca) {
-		peer.max_packet_data_size = negotiated_packet_data_size;
+		// make random max of [1020-1220]
+		const uint32_t random_max_data_size = (1024-4) + _rng()%201;
+		const uint32_t randomized_negotiated_packet_data_size = std::min(negotiated_packet_data_size, random_max_data_size);
+
+		peer.max_packet_data_size = randomized_negotiated_packet_data_size;
+
+		std::cerr << "NGCFT1: creating cca with max:" << peer.max_packet_data_size << "\n";
+
 		peer.cca = std::make_unique<CUBIC>(peer.max_packet_data_size);
 		//peer.cca = std::make_unique<LEDBAT>(peer.max_packet_data_size);
 		//peer.cca = std::make_unique<FlowOnly>(peer.max_packet_data_size);

solanaceae/ngc_ft1/ngcft1.hpp

@@ -17,6 +17,7 @@
 #include <map>
 #include <set>
 #include <memory>
+#include <random>
 
 namespace Events {
 
@@ -132,6 +133,8 @@ class NGCFT1 : public ToxEventI, public NGCEXTEventI, public NGCFT1EventProvider
 	ToxEventProviderI& _tep;
 	NGCEXTEventProviderI& _neep;
 
+	std::default_random_engine _rng{std::random_device{}()};
+
 	// TODO: config
 	size_t acks_per_packet {3u}; // 3
 	float init_retry_timeout_after {5.f}; // 10sec