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/client/state/ClientStateMachine.cpp

@@ -85,6 +85,9 @@ void processServerInitialParams(
   auto partialReliability = getIntegerParameter(
       static_cast<TransportParameterId>(kPartialReliabilityParameterId),
       serverParams.parameters);
+  auto activeConnectionIdLimit = getIntegerParameter(
+      TransportParameterId::active_connection_id_limit,
+      serverParams.parameters);
 
   if (!packetSize || *packetSize == 0) {
     packetSize = kDefaultMaxUDPPayload;
@@ -132,6 +135,9 @@ void processServerInitialParams(
     conn.udpSendPacketLen = *packetSize;
   }
 
+  conn.peerActiveConnectionIdLimit =
+      activeConnectionIdLimit.value_or(kDefaultConnectionIdLimit);
+
   if (partialReliability && *partialReliability != 0 &&
       conn.transportSettings.partialReliabilityEnabled) {
     conn.partialReliabilityEnabled = true;

quic/codec/QuicConnectionId.h

@@ -28,6 +28,8 @@ constexpr size_t kMinInitialDestinationConnIdLength = 8;
 // set conn id version at the first 4 bits
 constexpr uint8_t kShortVersionId = 0x1;
 
+constexpr uint64_t kDefaultConnectionIdLimit = 0;
+
 struct ConnectionId {
   uint8_t* data();
 

quic/handshake/TransportParameters.h

@@ -30,6 +30,7 @@ enum class TransportParameterId : uint16_t {
   max_ack_delay = 0x000b,
   disable_migration = 0x000c,
   preferred_address = 0x000d,
+  active_connection_id_limit = 0x000e
 };
 
 struct TransportParameter {

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;

quic/state/StateData.h

@@ -479,6 +479,8 @@ struct QuicConnectionStateBase {
   // Time at which the connection started.
   TimePoint connectionTime;
 
+  uint64_t peerActiveConnectionIdLimit{kDefaultConnectionIdLimit};
+
   // The current connection id. This will eventually be negotiated
   // with the peer.
   folly::Optional<ConnectionId> clientConnectionId;