active_connection_id_limit transport parameter

Summary:
^

This parameter was added in d-21. Default value is 0 meaning no provided
connection id apart from the initial ones. This limits the amount of connection
ids the peer provides via `NEW_CONNECTION_ID` frame.

Diff to set this value will be added in later, along with `NEW_CONNECTION_ID`.

Reviewed By: JunqiWang

Differential Revision: D17532007

fbshipit-source-id: 5b86f69a8d3372fbcb7e0882508ea2661a9d4864

quic/server/state/ServerStateMachine.cpp

@@ -110,6 +110,10 @@ void processClientInitialParams(
   auto partialReliability = getIntegerParameter(
       static_cast<TransportParameterId>(kPartialReliabilityParameterId),
       clientParams.parameters);
+  auto activeConnectionIdLimit = getIntegerParameter(
+      TransportParameterId::active_connection_id_limit,
+      clientParams.parameters);
+
   if (!packetSize || *packetSize == 0) {
     packetSize = kDefaultMaxUDPPayload;
   }
@@ -154,6 +158,9 @@ void processClientInitialParams(
     conn.udpSendPacketLen = *packetSize;
   }
 
+  conn.peerActiveConnectionIdLimit =
+      activeConnectionIdLimit.value_or(kDefaultConnectionIdLimit);
+
   if (partialReliability && *partialReliability != 0 &&
       conn.transportSettings.partialReliabilityEnabled) {
     conn.partialReliabilityEnabled = true;