quic: use SocketAddressLRU to track known SocketAddress info

jasnell · jasnell · commit f75e69a94bef · 2020-08-10T07:52:06.000-07:00
Using the `SocketAddressLRU` utility allows us to put an upper bound on the amount of memory that will be used to track known SocketAddress information (such as current number of connections, validation status, reset and retry counts, etc. The LRU is bounded by both max size and time, with any entry older than 10 seconds dropped whenever another item is accessed or updated. PR-URL: #34618 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Rich Trott <rtrott@gmail.com>
diff --git a/src/quic/node_quic_socket-inl.h b/src/quic/node_quic_socket-inl.h
@@ -4,7 +4,7 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include "node_quic_socket.h"
-#include "node_sockaddr.h"
+#include "node_sockaddr-inl.h"
 #include "node_quic_session.h"
 #include "node_crypto.h"
 #include "debug_utils-inl.h"
@@ -112,33 +112,27 @@ void QuicSocket::ReportSendError(int error) {
 }
 
 void QuicSocket::IncrementStatelessResetCounter(const SocketAddress& addr) {
-  reset_counts_[addr]++;
+  addrLRU_.Upsert(addr)->reset_count++;
 }
 
 void QuicSocket::IncrementSocketAddressCounter(const SocketAddress& addr) {
-  addr_counts_[addr]++;
+  addrLRU_.Upsert(addr)->active_connections++;
 }
 
 void QuicSocket::DecrementSocketAddressCounter(const SocketAddress& addr) {
-  auto it = addr_counts_.find(addr);
-  if (it == std::end(addr_counts_))
-    return;
-  it->second--;
-  // Remove the address if the counter reaches zero again.
-  if (it->second == 0) {
-    addr_counts_.erase(addr);
-    reset_counts_.erase(addr);
-  }
+  SocketAddressInfo* counts = addrLRU_.Peek(addr);
+  if (counts != nullptr && counts->active_connections > 0)
+    counts->active_connections--;
 }
 
 size_t QuicSocket::GetCurrentSocketAddressCounter(const SocketAddress& addr) {
-  auto it = addr_counts_.find(addr);
-  return it == std::end(addr_counts_) ? 0 : it->second;
+  SocketAddressInfo* counts = addrLRU_.Peek(addr);
+  return counts != nullptr ? counts->active_connections : 0;
 }
 
 size_t QuicSocket::GetCurrentStatelessResetCounter(const SocketAddress& addr) {
-  auto it = reset_counts_.find(addr);
-  return it == std::end(reset_counts_) ? 0 : it->second;
+  SocketAddressInfo* counts = addrLRU_.Peek(addr);
+  return counts != nullptr ? counts->reset_count : 0;
 }
 
 void QuicSocket::ServerBusy(bool on) {
@@ -160,22 +154,12 @@ void QuicSocket::set_diagnostic_packet_loss(double rx, double tx) {
 }
 
 void QuicSocket::set_validated_address(const SocketAddress& addr) {
-  if (has_option_validate_address_lru()) {
-    // Remove the oldest item if we've hit the LRU limit
-    validated_addrs_.push_back(SocketAddress::Hash()(addr));
-    if (validated_addrs_.size() > kMaxValidateAddressLru)
-      validated_addrs_.pop_front();
-  }
+  addrLRU_.Upsert(addr)->validated = true;
 }
 
 bool QuicSocket::is_validated_address(const SocketAddress& addr) const {
-  if (has_option_validate_address_lru()) {
-    auto res = std::find(std::begin(validated_addrs_),
-                         std::end(validated_addrs_),
-                         SocketAddress::Hash()(addr));
-    return res != std::end(validated_addrs_);
-  }
-  return false;
+  auto info = addrLRU_.Peek(addr);
+  return info != nullptr ? info->validated : false;
 }
 
 void QuicSocket::AddSession(
diff --git a/src/quic/node_quic_socket.cc b/src/quic/node_quic_socket.cc
@@ -260,6 +260,7 @@ QuicSocket::QuicSocket(
       retry_token_expiration_(retry_token_expiration),
       qlog_(qlog),
       server_alpn_(NGHTTP3_ALPN_H3),
+      addrLRU_(DEFAULT_MAX_SOCKETADDRESS_LRU_SIZE),
       quic_state_(quic_state) {
   MakeWeak();
   PushListener(&default_listener_);
@@ -308,10 +309,8 @@ void QuicSocket::MemoryInfo(MemoryTracker* tracker) const {
   tracker->TrackField("endpoints", endpoints_);
   tracker->TrackField("sessions", sessions_);
   tracker->TrackField("dcid_to_scid", dcid_to_scid_);
-  tracker->TrackField("addr_counts", addr_counts_);
-  tracker->TrackField("reset_counts", reset_counts_);
+  tracker->TrackField("address_counts", addrLRU_);
   tracker->TrackField("token_map", token_map_);
-  tracker->TrackField("validated_addrs", validated_addrs_);
   StatsBase::StatsMemoryInfo(tracker);
   tracker->TrackFieldWithSize(
       "current_ngtcp2_memory",
@@ -977,6 +976,18 @@ void QuicSocket::RemoveListener(QuicSocketListener* listener) {
   listener->previous_listener_ = nullptr;
 }
 
+bool QuicSocket::SocketAddressInfoTraits::CheckExpired(
+    const SocketAddress& address,
+    const Type& type) {
+  return (uv_hrtime() - type.timestamp) > 1e10;  // 10 seconds.
+}
+
+void QuicSocket::SocketAddressInfoTraits::Touch(
+    const SocketAddress& address,
+    Type* type) {
+  type->timestamp = uv_hrtime();
+}
+
 // JavaScript API
 namespace {
 void NewQuicEndpoint(const FunctionCallbackInfo<Value>& args) {
diff --git a/src/quic/node_quic_socket.h b/src/quic/node_quic_socket.h
@@ -35,6 +35,8 @@ namespace quic {
 class QuicSocket;
 class QuicEndpoint;
 
+constexpr size_t DEFAULT_MAX_SOCKETADDRESS_LRU_SIZE = 1000;
+
 #define QUICSOCKET_OPTIONS(V)                                                  \
     V(VALIDATE_ADDRESS, validate_address)                                      \
     V(VALIDATE_ADDRESS_LRU, validate_address_lru)
@@ -544,36 +546,24 @@ class QuicSocket : public AsyncWrap,
   uint8_t token_secret_[kTokenSecretLen];
   uint8_t reset_token_secret_[NGTCP2_STATELESS_RESET_TOKENLEN];
 
-  // Counts the number of active connections per remote
-  // address. A custom std::hash specialization for
-  // sockaddr instances is used. Values are incremented
-  // when a QuicSession is added to the socket, and
-  // decremented when the QuicSession is removed. If the
-  // value reaches the value of max_connections_per_host_,
-  // attempts to create new connections will be ignored
-  // until the value falls back below the limit.
-  SocketAddress::Map<size_t> addr_counts_;
-
-  // Counts the number of stateless resets sent per
-  // remote address.
-  // TODO(@jasnell): this counter persists through the
-  // lifetime of the QuicSocket, and therefore can become
-  // a possible risk. Specifically, a malicious peer could
-  // attempt the local peer to count an increasingly large
-  // number of remote addresses. Need to mitigate the
-  // potential risk.
-  SocketAddress::Map<size_t> reset_counts_;
-
-  // Counts the number of retry attempts sent per
-  // remote address.
+  struct SocketAddressInfo {
+    size_t active_connections;
+    size_t reset_count;
+    size_t retry_count;
+    bool validated;
+    uint64_t timestamp;
+  };
 
-  StatelessResetToken::Map<QuicSession> token_map_;
+  struct SocketAddressInfoTraits {
+    using Type = SocketAddressInfo;
 
-  // The validated_addrs_ vector is used as an LRU cache for
-  // validated addresses only when the VALIDATE_ADDRESS_LRU
-  // option is set.
-  typedef size_t SocketAddressHash;
-  std::deque<SocketAddressHash> validated_addrs_;
+    static bool CheckExpired(const SocketAddress& address, const Type& type);
+    static void Touch(const SocketAddress& address, Type* type);
+  };
+
+  SocketAddressLRU<SocketAddressInfoTraits> addrLRU_;
+
+  StatelessResetToken::Map<QuicSession> token_map_;
 
   class SendWrap : public ReqWrap<uv_udp_send_t> {
    public:
