quic: add applicationOptions to session

Signed-off-by: James M Snell <jasnell@gmail.com>
PR-URL: #63267
Backport-PR-URL: #64675
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

doc/api/quic.md

@@ -724,6 +724,18 @@ added: v23.8.0
 
 A `QuicSession` represents the local side of a QUIC connection.
 
+### `session.applicationOptions`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {quic.ApplicationOptions}
+
+The current application-level options for this session. These include settings
+that are specific to the negotiated application protocol (e.g. HTTP/3) and may
+be negotiated separately from the transport parameters. Read only.
+
 ### `session.close([options])`
 
 <!-- YAML
@@ -2218,6 +2230,70 @@ added: v23.8.0
 
 ## Types
 
+### type: `ApplicationOptions`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {Object}
+
+The application specific options.
+
+#### `applicationOptions.maxHeaderPairs`
+
+* Type: {bigint|number}
+
+Maximum number of header name-value pairs accepted per header block.
+Headers beyond this limit are silently dropped. **Default:** `128`
+
+#### `applicationOptions.maxHeaderLength`
+
+* Type: {bigint|number}
+
+Maximum total byte length of all header names and values combined per header
+block. Headers that would push the total over this limit are silently
+dropped. **Default:** `8192`
+
+#### `applicationOptions.maxFieldSectionSize`
+
+* Type: {bigint|number}
+
+Maximum size of a compressed header field section (QPACK). `0` means
+unlimited. **Default:** `0`
+
+#### `applicationOptions.qpackMaxDTableCapacity`
+
+* Type: {bigint|number}
+
+QPACK dynamic table capacity in bytes. Set to `0` to disable the dynamic
+table. **Default:** `4096`
+
+#### `applicationOptions.qpackEncoderMaxDTableCapacity`
+
+* Type: {bigint|number}
+
+QPACK encoder maximum dynamic table capacity. **Default:** `4096`
+
+#### `applicationOptions.qpackBlockedStreams`
+
+* Type: {bigint|number}
+
+Maximum number of streams that can e blocked waiting for QPACK dynamic table
+updates. **Default:** `100`
+
+#### `applicationOptions.enableConnectProtocol`
+
+* Type: {boolean}
+
+Enable the extended CONNECT protocol (RFC 9220). **Default:** `false`
+
+#### `applicationOptions.enableDatagrams`
+
+* Type: {boolean}
+
+Enable HTTP/3 datagrams (RFC 9297). **Default:** `false`
+
 ### Type: `EndpointOptions`
 
 <!-- YAML
@@ -2474,30 +2550,9 @@ Default: `'h3'`
 added: REPLACEME
 -->
 
-* Type: {Object}
+* Type: {quic.ApplicationOptions}
 
-HTTP/3 application-specific options. These only apply when the negotiated
-ALPN selects the HTTP/3 application (`'h3'`).
-
-* `maxHeaderPairs` {number} Maximum number of header name-value pairs
-  accepted per header block. Headers beyond this limit are silently
-  dropped. **Default:** `128`
-* `maxHeaderLength` {number} Maximum total byte length of all header
-  names and values combined per header block. Headers that would push
-  the total over this limit are silently dropped. **Default:** `8192`
-* `maxFieldSectionSize` {number} Maximum size of a compressed header
-  field section (QPACK). `0` means unlimited. **Default:** `0`
-* `qpackMaxDTableCapacity` {number} QPACK dynamic table capacity in
-  bytes. Set to `0` to disable the dynamic table. **Default:** `4096`
-* `qpackEncoderMaxDTableCapacity` {number} QPACK encoder maximum
-  dynamic table capacity. **Default:** `4096`
-* `qpackBlockedStreams` {number} Maximum number of streams that can
-  be blocked waiting for QPACK dynamic table updates.
-  **Default:** `100`
-* `enableConnectProtocol` {boolean} Enable the extended CONNECT
-  protocol (RFC 9220). **Default:** `false`
-* `enableDatagrams` {boolean} Enable HTTP/3 datagrams (RFC 9297).
-  **Default:** `false`
+Application-specific options.
 
 ```mjs
 const { listen } = await import('node:quic');

lib/internal/quic/quic.js

@@ -2678,6 +2678,14 @@ class QuicSession {
     debug('session created');
   }
 
+  get applicationOptions() {
+    // We don't cache application options because they may be updated by the
+    // C++ layer after session creation depending on the behavior of the
+    // application.
+    if (this.destroyed) return null;
+    return this.#handle.applicationOptions();
+  }
+
   get localTransportParams() {
     if (this.#inner.localTransportParams !== undefined) {
       return this.#inner.localTransportParams;

src/quic/application.cc

@@ -19,9 +19,13 @@
 
 namespace node {
 
+using v8::BigInt;
+using v8::Boolean;
+using v8::DictionaryTemplate;
 using v8::Just;
 using v8::Local;
 using v8::Maybe;
+using v8::MaybeLocal;
 using v8::Nothing;
 using v8::Object;
 using v8::Value;
@@ -114,6 +118,44 @@ Maybe<Session::Application_Options> Session::Application_Options::From(
   return Just<Application_Options>(options);
 }
 
+MaybeLocal<Object> Session::Application_Options::ToObject(
+    Environment* env) const {
+  auto& binding_data = BindingData::Get(env);
+  auto tmpl = binding_data.application_options_template();
+  static constexpr std::string_view names[] = {
+      "maxHeaderPairs",
+      "maxHeaderLength",
+      "maxFieldSectionSize",
+      "qpackMaxDtableCapacity",
+      "qpackEncoderMaxDtableCapacity",
+      "qpackBlockedStreams",
+      "enableConnectProtocol",
+      "enableDatagrams",
+  };
+  if (tmpl.IsEmpty()) {
+    tmpl = DictionaryTemplate::New(env->isolate(), names);
+    binding_data.set_application_options_template(tmpl);
+  }
+  MaybeLocal<Value> values[] = {
+      BigInt::NewFromUnsigned(env->isolate(), max_header_pairs),
+      BigInt::NewFromUnsigned(env->isolate(), max_header_length),
+      BigInt::NewFromUnsigned(env->isolate(), max_field_section_size),
+      BigInt::NewFromUnsigned(env->isolate(), qpack_max_dtable_capacity),
+      BigInt::NewFromUnsigned(env->isolate(),
+                              qpack_encoder_max_dtable_capacity),
+      BigInt::NewFromUnsigned(env->isolate(), qpack_blocked_streams),
+      Boolean::New(env->isolate(), enable_connect_protocol),
+      Boolean::New(env->isolate(), enable_datagrams),
+  };
+  static_assert(std::size(values) == std::size(names));
+
+  auto obj = tmpl->NewInstance(env->context(), values);
+  if (obj->SetPrototypeV2(env->context(), Null(env->isolate())).IsNothing()) {
+    return {};
+  }
+  return obj;
+}
+
 // ============================================================================
 
 std::string Session::Application::StreamData::ToString() const {
@@ -655,7 +697,10 @@ class DefaultApplication final : public Session::Application {
   // Marked NOLINT because the cpp linter gets confused about this using
   // statement not being sorted with the using v8 statements at the top
   // of the namespace.
-  using Application::Application;  // NOLINT
+  DefaultApplication(Session* session, const Options& options)
+      : Session::Application(session, options), options_(options) {}
+
+  const Options& options() const override { return options_; }
 
   Session::Application::Type type() const override {
     return Session::Application::Type::DEFAULT;
@@ -827,6 +872,8 @@ class DefaultApplication final : public Session::Application {
     }
   }
 
+  Options options_;
+
   Stream::Queue stream_queue_;
 };
 

src/quic/application.h

@@ -38,6 +38,10 @@ class Session::Application : public MemoryRetainer {
   Application(Session* session, const Options& options);
   DISALLOW_COPY_AND_MOVE(Application)
 
+  // Get the active options for this application. These may differ from the
+  // options passed at construction time since some options can be negotiated.
+  virtual const Options& options() const = 0;
+
   // The type of Application, exposed via the session state so JS
   // can observe which Application was selected after ALPN negotiation.
   // This is used primarily for testing/debugging.

src/quic/bindingdata.cc

@@ -385,7 +385,17 @@ void BindingData::set_transport_params_template(
 
 Local<DictionaryTemplate> BindingData::transport_params_template() const {
   return PersistentToLocal::Default(env()->isolate(),
-    transport_params_template_);
+                                    transport_params_template_);
+}
+
+void BindingData::set_application_options_template(
+    Local<DictionaryTemplate> tmpl) {
+  application_options_template_.Reset(env()->isolate(), tmpl);
+}
+
+Local<DictionaryTemplate> BindingData::application_options_template() const {
+  return PersistentToLocal::Default(env()->isolate(),
+                                    application_options_template_);
 }
 
 #define V(name, _)                                                             \

src/quic/bindingdata.h

@@ -306,6 +306,9 @@ class BindingData final
   void set_transport_params_template(v8::Local<v8::DictionaryTemplate> tmpl);
   v8::Local<v8::DictionaryTemplate> transport_params_template() const;
 
+  void set_application_options_template(v8::Local<v8::DictionaryTemplate> tmpl);
+  v8::Local<v8::DictionaryTemplate> application_options_template() const;
+
 #define V(name, _)                                                             \
   void set_##name##_callback(v8::Local<v8::Function> fn);                      \
   v8::Local<v8::Function> name##_callback() const;
@@ -325,6 +328,7 @@ class BindingData final
 #undef V
 
   v8::Global<v8::DictionaryTemplate> transport_params_template_;
+  v8::Global<v8::DictionaryTemplate> application_options_template_;
 
 #define V(name, _) v8::Global<v8::Function> name##_callback_;
   QUIC_JS_CALLBACKS(V)

src/quic/http3.cc

@@ -157,6 +157,8 @@ class Http3ApplicationImpl final : public Session::Application {
     session->set_priority_supported();
   }
 
+  const Options& options() const override { return options_; }
+
   Session::Application::Type type() const override {
     return Session::Application::Type::HTTP3;
   }

src/quic/session.cc

@@ -193,6 +193,7 @@ uint64_t MaxDatagramPayload(uint64_t max_frame_size) {
   V(SendDatagram, sendDatagram, SIDE_EFFECT)                                   \
   V(LocalTransportParams, localTransportParams, NO_SIDE_EFFECT)                \
   V(RemoteTransportParams, remoteTransportParams, NO_SIDE_EFFECT)              \
+  V(ApplicationOptions, applicationOptions, NO_SIDE_EFFECT)
 
 struct Session::State final {
 #define V(_, name, type) type name;
@@ -1195,6 +1196,24 @@ struct Session::Impl final : public MemoryRetainer {
       args.GetReturnValue().Set(obj);
     }
   }
+
+  JS_METHOD(ApplicationOptions) {
+    auto env = Environment::GetCurrent(args);
+    Session* session;
+    ASSIGN_OR_RETURN_UNWRAP(&session, args.This());
+
+    Local<Object> obj;
+    if (!session->has_application()) {
+      // The application has not yet been selected (ALPN negotiation is not
+      // yet complete on the server) or the session has been destroyed. In
+      // either case, the application options are not available.
+      return args.GetReturnValue().SetUndefined();
+    }
+    auto& options = session->application().options();
+    if (options.ToObject(env).ToLocal(&obj)) {
+      args.GetReturnValue().Set(obj);
+    }
+  }
   // Internal ngtcp2 callbacks
 
   static int on_acknowledge_stream_data_offset(ngtcp2_conn* conn,
@@ -2082,6 +2101,10 @@ TLSSession& Session::tls_session() const {
   return *tls_session_;
 }
 
+bool Session::has_application() const {
+  return !is_destroyed() && impl_->application_ != nullptr;
+}
+
 Session::Application& Session::application() const {
   DCHECK(!is_destroyed());
   DCHECK(impl_->application_);

src/quic/session.h

@@ -91,6 +91,8 @@ class Session final : public AsyncWrap, private SessionTicket::AppData::Source {
 
     std::string ToString() const;
 
+    v8::MaybeLocal<v8::Object> ToObject(Environment* env) const;
+
     static const Application_Options kDefault;
   };
 
@@ -324,6 +326,7 @@ class Session final : public AsyncWrap, private SessionTicket::AppData::Source {
   uint32_t version() const;
   Endpoint& endpoint() const;
   TLSSession& tls_session() const;
+  bool has_application() const;
   Application& application() const;
   const Config& config() const;
   const Options& options() const;