quic: update http3 impl details

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: Opencode/Opus 4.6
PR-URL: #62387
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>

Author: jasnell

src/quic/http3.cc

@@ -319,14 +319,20 @@ class Http3ApplicationImpl final : public Session::Application {
 
   void CollectSessionTicketAppData(
       SessionTicket::AppData* app_data) const override {
-    // TODO(@jasnell): There's currently nothing to store but there may be
-    // later.
+    // TODO(@jasnell): When HTTP/3 settings become dynamic or
+    // configurable per-connection, store them here so they can be
+    // validated on 0-RTT resumption. Candidates include:
+    // max_field_section_size, qpack_max_dtable_capacity,
+    // qpack_encoder_max_dtable_capacity, qpack_blocked_streams,
+    // enable_connect_protocol, and enable_datagrams. On extraction,
+    // compare stored values against current settings and return
+    // TICKET_IGNORE_RENEW if incompatible.
   }
 
   SessionTicket::AppData::Status ExtractSessionTicketAppData(
       const SessionTicket::AppData& app_data,
       SessionTicket::AppData::Source::Flag flag) override {
-    // There's currently nothing stored here but we might do so later.
+    // See CollectSessionTicketAppData above.
     return flag == SessionTicket::AppData::Source::Flag::STATUS_RENEW
                ? SessionTicket::AppData::Status::TICKET_USE_RENEW
                : SessionTicket::AppData::Status::TICKET_USE;
@@ -448,10 +454,42 @@ class Http3ApplicationImpl final : public Session::Application {
     return false;
   }
 
+  void SetStreamPriority(const Stream& stream,
+                        StreamPriority priority,
+                        StreamPriorityFlags flags) override {
+    nghttp3_pri pri;
+    pri.inc = (flags == StreamPriorityFlags::NON_INCREMENTAL) ? 0 : 1;
+    switch (priority) {
+      case StreamPriority::HIGH:
+        pri.urgency = NGHTTP3_URGENCY_HIGH;
+        break;
+      case StreamPriority::LOW:
+        pri.urgency = NGHTTP3_URGENCY_LOW;
+        break;
+      default:
+        pri.urgency = NGHTTP3_DEFAULT_URGENCY;
+        break;
+    }
+    if (session().is_server()) {
+      nghttp3_conn_set_server_stream_priority(
+          *this, stream.id(), &pri);
+    }
+    // Client-side priority is set at request submission time via
+    // nghttp3_conn_submit_request and is not typically changed
+    // after the fact. The client API takes a serialized RFC 9218
+    // field value rather than an nghttp3_pri struct.
+  }
+
   StreamPriority GetStreamPriority(const Stream& stream) override {
     nghttp3_pri pri;
     if (nghttp3_conn_get_stream_priority(*this, &pri, stream.id()) == 0) {
-      // TODO(@jasnell): Support the incremental flag
+      // TODO(@jasnell): The nghttp3_pri.inc (incremental) flag is
+      // not yet exposed. When priority-based stream scheduling is
+      // implemented, GetStreamPriority should return both urgency
+      // and the incremental flag (making get/set symmetrical).
+      // The inc flag determines whether the server should interleave
+      // data from this stream with others of the same urgency
+      // (inc=1) or complete it first (inc=0).
       switch (pri.urgency) {
         case NGHTTP3_URGENCY_HIGH:
           return StreamPriority::HIGH;
@@ -673,22 +711,23 @@ class Http3ApplicationImpl final : public Session::Application {
     stream->ReceiveStreamReset(0, QuicError::ForApplication(app_error_code));
   }
 
-  void OnShutdown() {
-    // This callback is invoked when we receive a request to gracefully shutdown
-    // the http3 connection. For client, the id is the stream id of a client
-    // initiated stream. For server, the id is the stream id of a server
-    // initiated stream. Once received, the other side is guaranteed not to
-    // process any more data.
-
-    // On the client side, if id is equal to NGHTTP3_SHUTDOWN_NOTICE_STREAM_ID,
-    // or on the server if the id is equal to NGHTTP3_SHUTDOWN_NOTICE_PUSH_ID,
-    // then this is a request to begin a graceful shutdown.
-
-    // This can be called multiple times but the id can only stay the same or
-    // *decrease*.
-
-    // TODO(@jasnell): Need to determine exactly how to handle.
-    Debug(&session(), "HTTP/3 application received shutdown notice");
+  void OnShutdown(int64_t id) {
+    // The peer has sent a GOAWAY frame initiating a graceful shutdown.
+    // For a client, id is the stream ID beyond which the server will
+    // not process requests. For a server, id is a push ID (server
+    // push is not implemented). Streams/pushes with IDs >= id will
+    // not be processed by the peer.
+    //
+    // When id equals NGHTTP3_SHUTDOWN_NOTICE_STREAM_ID (client) or
+    // NGHTTP3_SHUTDOWN_NOTICE_PUSH_ID (server), this is a notice of
+    // intent to shut down rather than an immediate refusal.
+    //
+    // This can be called multiple times with a decreasing id as the
+    // peer progressively reduces the set of streams it will process.
+    Debug(&session(),
+          "HTTP/3 received GOAWAY (id=%" PRIi64 ")",
+          id);
+    session().Close(Session::CloseMethod::GRACEFUL);
   }
 
   void OnReceiveSettings(const nghttp3_settings* settings) {
@@ -747,9 +786,55 @@ class Http3ApplicationImpl final : public Session::Application {
                                              uint32_t* pflags,
                                              void* conn_user_data,
                                              void* stream_user_data) {
-    return NGTCP2_SUCCESS;
+    auto ptr = From(conn, conn_user_data);
+    CHECK_NOT_NULL(ptr);
+    auto& app = *ptr;
+    NgHttp3CallbackScope scope(app.env());
+
+    auto stream = app.session().FindStream(stream_id);
+    if (!stream) return NGHTTP3_ERR_CALLBACK_FAILURE;
+
+    if (stream->is_eos()) {
+      *pflags |= NGHTTP3_DATA_FLAG_EOF;
+      return 0;
+    }
+
+    size_t max_count = std::min(veccnt,
+                                static_cast<size_t>(kMaxVectorCount));
+    nghttp3_ssize result = 0;
+
+    auto next = [&](int status,
+                    const ngtcp2_vec* data,
+                    size_t count,
+                    bob::Done done) {
+      switch (status) {
+        case bob::Status::STATUS_BLOCK:
+        case bob::Status::STATUS_WAIT:
+          result = NGHTTP3_ERR_WOULDBLOCK;
+          return;
+        case bob::Status::STATUS_EOS:
+          *pflags |= NGHTTP3_DATA_FLAG_EOF;
+          break;
+      }
+      count = std::min(count, max_count);
+      for (size_t n = 0; n < count; n++) {
+        vec[n].base = data[n].base;
+        vec[n].len = data[n].len;
+      }
+      result = static_cast<nghttp3_ssize>(count);
+    };
+
+    ngtcp2_vec data[kMaxVectorCount];
+    stream->Pull(std::move(next),
+                   bob::Options::OPTIONS_SYNC,
+                   data,
+                   max_count,
+                   max_count);
+
+    return result;
   }
 
+
   static int on_acked_stream_data(nghttp3_conn* conn,
                                   int64_t stream_id,
                                   uint64_t datalen,
@@ -934,7 +1019,7 @@ class Http3ApplicationImpl final : public Session::Application {
 
   static int on_shutdown(nghttp3_conn* conn, int64_t id, void* conn_user_data) {
     NGHTTP3_CALLBACK_SCOPE(app);
-    app.OnShutdown();
+    app.OnShutdown(id);
     return NGTCP2_SUCCESS;
   }
 
@@ -950,14 +1035,14 @@ class Http3ApplicationImpl final : public Session::Application {
                                const uint8_t* origin,
                                size_t originlen,
                                void* conn_user_data) {
-    // TODO(@jasnell): Handle the origin callback. This is called
-    // when a single origin in an ORIGIN frame is received.
+    // ORIGIN frames (RFC 8336) are used for connection coalescing
+    // across multiple origins. Not yet implemented u2014 requires
+    // connection pooling and multi-origin reuse support.
     return NGTCP2_SUCCESS;
   }
 
   static int on_end_origin(nghttp3_conn* conn, void* conn_user_data) {
-    // TODO(@jasnell): Handle the end of origin callback. This is called
-    // when the end of an ORIGIN frame is received.
+    // See on_receive_origin above.
     return NGTCP2_SUCCESS;
   }