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quic: extract transport logic from Application to Session #64127

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12 changes: 6 additions & 6 deletions src/quic/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -77,7 +77,7 @@ data channels that carry application data.

Every entry point that may generate outbound data creates a
`SendPendingDataScope`. Scopes nest — an internal depth counter ensures
`Application::SendPendingData()` is called exactly once, when the outermost
`Session::SendPendingData()` is called exactly once, when the outermost
scope exits:

```cpp
Expand Down Expand Up @@ -218,13 +218,13 @@ Session::Receive()

```text
SendPendingDataScope::~SendPendingDataScope()
→ Application::SendPendingData()
→ Session::SendPendingData()
Loop (up to max_packet_count):
├── GetStreamData() // pull data from next stream
│ └── stream->Pull() // bob pull from Outbound→DataQueue
├── WriteVStream() // ngtcp2_conn_writev_stream()
├── application().GetStreamData() // pull data from next stream
│ └── stream->Pull() // bob pull from Outbound→DataQueue
├── WriteVStream() // ngtcp2_conn_writev_stream()
│ encrypts, frames, paces
├── if ndatalen > 0: StreamCommit()
├── if ndatalen > 0: application().StreamCommit()
│ stream->Commit(datalen, fin)
├── if nwrite > 0: Send() // uv_udp_send()
├── if WRITE_MORE: continue // room for more in this packet
Expand Down
442 changes: 0 additions & 442 deletions src/quic/application.cc
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56 changes: 0 additions & 56 deletions src/quic/application.h
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Original file line number Diff line number Diff line change
Expand Up @@ -205,10 +205,6 @@ class Session::Application : public MemoryRetainer {
return false;
}

// Signals to the Application that it should serialize and transmit any
// pending session and stream packets it has accumulated.
void SendPendingData();

// Returns true if the application protocol supports sending and
// receiving headers on streams (e.g. HTTP/3). Applications that
// do not support headers should return false (the default).
Expand Down Expand Up @@ -243,10 +239,6 @@ class Session::Application : public MemoryRetainer {
return {StreamPriority::DEFAULT, StreamPriorityFlags::NON_INCREMENTAL};
}

// The StreamData struct is used by the application to pass pending stream
// data to the session for transmission.
struct StreamData;

virtual int GetStreamData(StreamData* data) = 0;
virtual bool StreamCommit(StreamData* data, size_t datalen) = 0;

Expand All @@ -262,57 +254,9 @@ class Session::Application : public MemoryRetainer {
}

private:
Packet::Ptr CreateStreamDataPacket();

// Tries to pack a pending datagram into the current packet buffer.
// If < 0 is returned, either NGTCP2_ERR_WRITE_MORE or a fatal error is
// returned; the caller must check. If > 0 is returned, the packet is done
// and the value is the size of the finalized packet. If 0 is returned,
// the datagram is either congestion limited or was abandoned
ssize_t TryWritePendingDatagram(PathStorage* path,
uint8_t* dest,
size_t destlen,
uint64_t ts);

// Write the given stream_data into the buffer. The PacketInfo out-param
// is populated by ngtcp2 with per-packet metadata (e.g., ECN codepoint)
// that should be applied when sending the packet.
ssize_t WriteVStream(PathStorage* path,
PacketInfo* pi,
uint8_t* buf,
ssize_t* ndatalen,
size_t max_packet_size,
const StreamData& stream_data,
uint64_t ts);

Session* session_ = nullptr;
};

struct Session::Application::StreamData final {
// The actual number of vectors in the struct, up to kMaxVectorCount.
size_t count = 0;
// The stream identifier. If this is a negative value then no stream is
// identified.
stream_id id = -1;
int fin = 0;
ngtcp2_vec data[kMaxVectorCount]{};
BaseObjectPtr<Stream> stream;

static_assert(sizeof(ngtcp2_vec) == sizeof(nghttp3_vec) &&
alignof(ngtcp2_vec) == alignof(nghttp3_vec) &&
offsetof(ngtcp2_vec, base) == offsetof(nghttp3_vec, base) &&
offsetof(ngtcp2_vec, len) == offsetof(nghttp3_vec, len),
"ngtcp2_vec and nghttp3_vec must have identical layout");
inline operator nghttp3_vec*() {
return reinterpret_cast<nghttp3_vec*>(data);
}

inline operator const ngtcp2_vec*() const { return data; }
inline operator ngtcp2_vec*() { return data; }

std::string ToString() const;
};

// Create a DefaultApplication for the given session.
std::unique_ptr<Session::Application> CreateDefaultApplication(
Session* session, const Session::Application_Options& options);
Expand Down
79 changes: 35 additions & 44 deletions src/quic/http3.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -209,24 +209,25 @@ class Http3ApplicationImpl final : public Session::Application {
started_ = true;
Debug(&session(), "Starting HTTP/3 application.");

auto params = ngtcp2_conn_get_remote_transport_params(session());
if (params == nullptr) [[unlikely]] {
const auto params = session().remote_transport_params();
if (!params) [[unlikely]] {
// The params are not available yet. Cannot start.
Debug(&session(),
"Cannot start HTTP/3 application yet. No remote transport params");
return false;
}

if (params->initial_max_streams_uni < 3) {
if (params.initial_max_streams_uni() < 3) {
// HTTP3 requires 3 unidirectional control streams to be opened in each
// direction in additional to the bidirectional streams that are used to
// actually carry request and response payload back and forth.
// See:
// https://nghttp2.org/nghttp3/programmers-guide.html#binding-control-streams
Debug(&session(),
"Cannot start HTTP/3 application. Initial max "
"unidirectional streams [%zu] is too low. Must be at least 3",
params->initial_max_streams_uni);
"unidirectional streams [%" PRIu64
"] is too low. Must be at least 3",
params.initial_max_streams_uni());
return false;
}

Expand All @@ -235,17 +236,14 @@ class Http3ApplicationImpl final : public Session::Application {
// of requests that the client can actually created.
if (session().is_server()) {
nghttp3_conn_set_max_client_streams_bidi(
*this, params->initial_max_streams_bidi);
*this, params.initial_max_streams_bidi());
}

Debug(&session(), "Creating and binding HTTP/3 control streams");
bool ret =
ngtcp2_conn_open_uni_stream(session(), &control_stream_id_, nullptr) ==
0 &&
ngtcp2_conn_open_uni_stream(
session(), &qpack_enc_stream_id_, nullptr) == 0 &&
ngtcp2_conn_open_uni_stream(
session(), &qpack_dec_stream_id_, nullptr) == 0 &&
session().OpenUni(&control_stream_id_) &&
session().OpenUni(&qpack_enc_stream_id_) &&
session().OpenUni(&qpack_dec_stream_id_) &&
nghttp3_conn_bind_control_stream(*this, control_stream_id_) == 0 &&
nghttp3_conn_bind_qpack_streams(
*this, qpack_enc_stream_id_, qpack_dec_stream_id_) == 0;
Expand Down Expand Up @@ -306,8 +304,7 @@ class Http3ApplicationImpl final : public Session::Application {
Debug(&session(),
"Extending stream and connection offset by %zd bytes",
nread);
session().ExtendStreamOffset(id, nread);
session().ExtendOffset(nread);
session().Consume(id, nread);
}

// If this data arrived as 0-RTT, mark the stream. We set it after
Expand Down Expand Up @@ -365,24 +362,11 @@ class Http3ApplicationImpl final : public Session::Application {
case EndpointLabel::LOCAL:
return;
case EndpointLabel::REMOTE: {
switch (direction) {
case Direction::BIDIRECTIONAL: {
Debug(&session(),
"HTTP/3 application extending max bidi streams by %" PRIu64,
max_streams);
ngtcp2_conn_extend_max_streams_bidi(
session(), static_cast<size_t>(max_streams));
break;
}
case Direction::UNIDIRECTIONAL: {
Debug(&session(),
"HTTP/3 application extending max uni streams by %" PRIu64,
max_streams);
ngtcp2_conn_extend_max_streams_uni(
session(), static_cast<size_t>(max_streams));
break;
}
}
Debug(&session(),
"HTTP/3 application extending max %s streams by %" PRIu64,
direction == Direction::BIDIRECTIONAL ? "bidi" : "uni",
max_streams);
session().ExtendMaxStreams(direction, max_streams);
}
}
}
Expand Down Expand Up @@ -530,8 +514,7 @@ class Http3ApplicationImpl final : public Session::Application {
return;
}

session().SetLastError(
QuicError::ForApplication(nghttp3_err_infer_quic_app_error_code(rv)));
session().SetApplicationError(nghttp3_err_infer_quic_app_error_code(rv));
session().Close();
}

Expand All @@ -548,8 +531,7 @@ class Http3ApplicationImpl final : public Session::Application {
return;
}

session().SetLastError(
QuicError::ForApplication(nghttp3_err_infer_quic_app_error_code(rv)));
session().SetApplicationError(nghttp3_err_infer_quic_app_error_code(rv));
session().Close();
}

Expand Down Expand Up @@ -688,12 +670,22 @@ class Http3ApplicationImpl final : public Session::Application {
}

int GetStreamData(StreamData* data) override {
static_assert(
sizeof(ngtcp2_vec) == sizeof(nghttp3_vec) &&
alignof(ngtcp2_vec) == alignof(nghttp3_vec) &&
offsetof(ngtcp2_vec, base) == offsetof(nghttp3_vec, base) &&
offsetof(ngtcp2_vec, len) == offsetof(nghttp3_vec, len),
"ngtcp2_vec and nghttp3_vec must have identical layout");
data->count = kMaxVectorCount;
ssize_t ret = 0;
Debug(&session(), "HTTP/3 application getting stream data");
if (conn_ && session().max_data_left()) {
ret = nghttp3_conn_writev_stream(
*this, &data->id, &data->fin, *data, data->count);
ret =
nghttp3_conn_writev_stream(*this,
&data->id,
&data->fin,
reinterpret_cast<nghttp3_vec*>(data->data),
data->count);
// A negative return value indicates an error.
if (ret < 0) {
return static_cast<int>(ret);
Expand All @@ -720,8 +712,7 @@ class Http3ApplicationImpl final : public Session::Application {
// nghttp3 tracks its own offset via add_write_offset.
int err = nghttp3_conn_add_write_offset(*this, data->id, datalen);
if (err != 0) {
session().SetLastError(QuicError::ForApplication(
nghttp3_err_infer_quic_app_error_code(err)));
session().SetApplicationError(nghttp3_err_infer_quic_app_error_code(err));
return false;
}
// Raw application bytes are committed to the stream's outbound
Expand Down Expand Up @@ -1211,10 +1202,10 @@ class Http3ApplicationImpl final : public Session::Application {
void* conn_user_data,
void* stream_user_data) {
NGHTTP3_CALLBACK_SCOPE(app);
auto& session = app.session();
Debug(&session, "HTTP/3 application deferred consume %zu bytes", consumed);
session.ExtendStreamOffset(id, consumed);
session.ExtendOffset(consumed);
Debug(&app.session(),
"HTTP/3 application deferred consume %zu bytes",
consumed);
app.session().Consume(id, consumed);
return NGTCP2_SUCCESS;
}

Expand Down
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