Crafter.Network/implementations/Crafter.Network-ClientQUIC.cpp
Jorijn van der Graaf 1b7417c2ba
feat(quic): QUICStream::SendAsync holds no thread and reports from SEND_COMPLETE
Native SendAsync was SendSync run as a pool task. That held a worker of
Crafter.Thread's pool, which the host shares and which runs each
worker's queue in order, for as long as msquic took to accept the
buffer, and a peer that reads slowly stretches that to its own pace: a
server streaming to a slow follower stalled the tasks queued behind it.
The task also reached back through `this`, so moving or destroying the
wrapper before it ran was a use-after-free, and two sends could reach
msquic out of order from two workers.

Now SendAsync copies the buffer into a SendRequest, hands it to msquic
and returns. SEND_COMPLETE, which msquic delivers exactly once for every
send it took and before the stream's SHUTDOWN_COMPLETE, frees the copy
and calls onSent on the msquic worker: true when msquic took the whole
buffer (in its send buffer or acknowledged, which is what SendSync's
return has always meant), false when it was canceled because the stream
or the connection ended first. Sends queue in msquic in call order and
none waits for another. A send msquic never took (a closed stream, a
moved-from wrapper, StreamSend refusing it) reports false from a pool
task, never from inside SendAsync, so a caller may hold a lock its own
callback takes. Only `impl` is read, not `handle`, so SendAsync is
callable from any thread, a callback included; on a stopped stream
msquic cancels the send.

BytesInFlight() and SendsInFlight() count what SendAsync and SendSync
handed msquic whose SEND_COMPLETE has not come, so a server can drop a
follower that falls too far behind.

Rewritten rather than added beside it: nothing in this repository calls
the native SendAsync (ListenerHTTP, WebTransport and ClientHTTP use
SendSync; the example's SendAsync is the browser build's), nor does any
consumer found here (3DForts uses SendSync natively); its contract is
unchanged, copy now and onSent once with whether it went; and the old
one's pool thread, `this` capture and reordering were defects, not
behaviour to keep. What changes is onSent's thread, msquic's worker
rather than a pool task, so a callback that blocks, a *Sync call above
all, now stalls its connection rather than a pool worker. The browser
build is untouched.

Breaking: native onSent runs on msquic's worker thread, not as a pool
task, and must not block.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-11-01 02:24:15 +01:00

1155 lines
50 KiB
C++

//SPDX-License-Identifier: LGPL-3.0-only
//SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
module;
#include <msquic.h>
#include <cstring>
module Crafter.Network:ClientQUIC_impl;
import :ClientQUIC;
import Crafter.Thread;
import std;
using namespace Crafter;
namespace {
// Process-wide msquic API table + registration. Initialised lazily on
// first ClientQUIC/ListenerQUIC construction; tear-down happens at
// process exit via the destructor of the static object.
struct MsQuicRuntime {
const QUIC_API_TABLE* api = nullptr;
HQUIC registration = nullptr;
std::mutex initMutex;
bool initialised = false;
void Ensure() {
std::lock_guard lock(initMutex);
if (initialised) return;
QUIC_STATUS s = MsQuicOpen2(&api);
if (QUIC_FAILED(s)) {
throw QUICException(std::format("MsQuicOpen2 failed: 0x{:x}", static_cast<unsigned>(s)));
}
QUIC_REGISTRATION_CONFIG regConfig{ "crafter.network", QUIC_EXECUTION_PROFILE_LOW_LATENCY };
s = api->RegistrationOpen(&regConfig, &registration);
if (QUIC_FAILED(s)) {
MsQuicClose(api);
api = nullptr;
throw QUICException(std::format("RegistrationOpen failed: 0x{:x}", static_cast<unsigned>(s)));
}
initialised = true;
}
~MsQuicRuntime() {
if (registration) api->RegistrationClose(registration);
if (api) MsQuicClose(api);
}
};
MsQuicRuntime& Runtime() {
static MsQuicRuntime r;
r.Ensure();
return r;
}
// Open-stream bookkeeping, shared by a connection and every stream on it.
// A stream counts as open from the moment msquic has a callback handler
// for it until its handle has been StreamClose'd. ~ClientQUIC drains this
// before closing the connection: QUICStream::Stop only *initiates* a
// shutdown whose async completion does the actual close, so without the
// wait a connection can be closed with streams still open on the msquic
// side.
//
// Reached through a shared_ptr rather than through the owning ClientQUIC*
// so that a stream finalising after the (bounded) wait gave up decrements
// a live object instead of a freed connection.
struct StreamRegistry {
std::mutex mtx;
std::condition_variable cv;
int open = 0;
void Add() {
std::lock_guard lk(mtx);
++open;
}
void Remove() {
{
std::lock_guard lk(mtx);
--open;
}
cv.notify_all();
}
// False if the timeout expired with streams still open.
bool WaitForDrain(std::chrono::milliseconds timeout) {
std::unique_lock lk(mtx);
return cv.wait_for(lk, timeout, [&]{ return open == 0; });
}
};
// ClientQUIC::OnClosed's state, shared by the ClientQUIC and whoever
// fires the callback: the SHUTDOWN_COMPLETE handler on an msquic worker,
// or a pool task when OnClosed is called after the close. Reached
// through a shared_ptr because the handler fires it after closing the
// connection handle, and from then on ~ClientQUIC, finding no handle
// left to claim, no longer waits for the worker and may free the Impl
// under it.
//
// The rules are std::stop_callback's: once ~ClientQUIC has set
// `ownerGone` the callback never starts; one already running on another
// thread is waited for, so the owner may free what the callback uses as
// soon as the destructor returns; one running on the destructor's own
// thread, a callback deleting its own connection, cannot be and is not.
struct CloseNotice {
std::mutex mtx;
std::condition_variable idle;
std::function<void()> callback;
bool closed = false; // shut down, and not by ~ClientQUIC
bool fired = false;
bool ownerGone = false; // ~ClientQUIC has begun
bool running = false;
std::thread::id runningOn;
// Runs the callback if it is due: closed, set, not yet run, and the
// owner still there.
static void Fire(const std::shared_ptr<CloseNotice>& notice) {
std::function<void()> callback;
{
std::lock_guard lk(notice->mtx);
if (!notice->closed || notice->fired || notice->ownerGone || !notice->callback) return;
notice->fired = true;
notice->running = true;
notice->runningOn = std::this_thread::get_id();
callback.swap(notice->callback);
}
callback();
// Destroyed before `running` drops, so a destructor waiting for
// us is never racing what the callback captured.
callback = nullptr;
{
std::lock_guard lk(notice->mtx);
notice->running = false;
}
notice->idle.notify_all();
}
// ~ClientQUIC's half: from here no callback starts, and one running
// on another thread has returned.
void OwnerGone() {
std::function<void()> dropped;
{
std::unique_lock lk(mtx);
ownerGone = true;
if (running && runningOn != std::this_thread::get_id()) {
idle.wait(lk, [&] { return !running; });
}
dropped.swap(callback);
}
}
};
// Bound on how long ~ClientQUIC waits for the connection's streams to
// finish closing. The decrements arrive on msquic worker threads, so an
// unbounded wait would turn a dropped peer into a hung destructor.
//
// Expiring is a bug, not a slow path: ConnectionShutdown makes msquic
// deliver SHUTDOWN_COMPLETE for every stream it knows about, OpenStream
// passes SHUTDOWN_ON_FAIL so a stream whose start lost the race to that
// shutdown gets one too, and QUICStream::Stop aborts the receive direction
// so a bidi stream does not sit waiting on a peer that will never close
// its send side. With those three the count always reaches zero; the bound
// only stops an msquic-side surprise from wedging the destructor outright.
constexpr std::chrono::milliseconds streamDrainTimeout{ 5000 };
// Bound on how long ~ClientQUIC then waits for the connection's shutdown
// to complete before it closes the handle. Closing earlier loses the
// CONNECTION_CLOSE frame: msquic sends it from a flush it queues while it
// processes ConnectionShutdown, a ConnectionClose that reaches the worker
// before that flush completes the shutdown silently (QuicConnTryClose's
// "silent close forced" path), and the flush is then skipped (FLUSH_SEND
// is ignored once ShutdownComplete is set). The peer learned of the close
// only at its idle timeout, two minutes by default; with no stream open
// the drain above returns at once, so that was the usual outcome.
// SHUTDOWN_COMPLETE comes about a round trip later, once the peer answers
// the close, or after msquic's closing period (three PTOs) when it does
// not. Either way the frame went out at the start, so the bound only
// stops a peer that is gone from holding the destructor that long.
constexpr std::chrono::milliseconds closeNotifyTimeout{ 1000 };
// Encode an ALPN string into the wire format msquic expects: a length
// byte followed by the ASCII characters. Lifetime of the returned buffer
// matches the caller's storage in `out`.
QUIC_BUFFER MakeAlpn(const std::string& alpn, std::vector<std::uint8_t>& out) {
if (alpn.size() > 255) throw QUICException("ALPN string too long (max 255)");
out.assign(alpn.begin(), alpn.end());
QUIC_BUFFER b{};
b.Length = static_cast<std::uint32_t>(out.size());
b.Buffer = out.data();
return b;
}
}
// ---------------- QUICStream::Impl ----------------
struct QUICStream::Impl {
// How one SendSync went, written by its SEND_COMPLETE under the stream's
// mutex. Shared with the waiting thread so the request can be freed by
// whichever side finishes with it, in either order.
struct SendOutcome {
bool done = false;
bool sent = false;
};
// One send handed to msquic: the copy it reads from, and the QUIC_BUFFER
// describing it, which msquic keeps a pointer to rather than copying.
// Owned by msquic from a successful StreamSend until that send's
// SEND_COMPLETE, which msquic delivers exactly once for every send it
// took (Canceled when the stream or the connection ended first) and
// always before the stream's SHUTDOWN_COMPLETE; that handler frees it.
// Who hears how it went: SendSync's waiting thread through `outcome`,
// or SendAsync's `onSent`.
struct SendRequest {
std::vector<char> bytes;
QUIC_BUFFER buffer{};
std::shared_ptr<SendOutcome> outcome;
std::function<void(bool sent)> onSent;
SendRequest(const void* data, std::uint32_t size)
: bytes(static_cast<const char*>(data), static_cast<const char*>(data) + size) {
buffer.Buffer = reinterpret_cast<std::uint8_t*>(bytes.data());
buffer.Length = size;
}
};
ClientQUIC* connection = nullptr;
std::mutex mtx;
std::condition_variable cv;
std::deque<std::vector<char>> pending;
bool peerSendClosed = false;
bool shutdownComplete = false;
// Sends handed to msquic whose SEND_COMPLETE has not come yet, under mtx.
std::uint64_t bytesInFlight = 0;
std::size_t sendsInFlight = 0;
// StreamSend for one request, counted in flight while msquic has it.
// False, with the request still the caller's, when msquic refused it:
// then no SEND_COMPLETE will come.
bool Send(HQUIC live, SendRequest* request, bool finish, QUIC_STATUS& status) {
{
std::lock_guard lk(mtx);
bytesInFlight += request->bytes.size();
++sendsInFlight;
}
// Counted first: SEND_COMPLETE can run on the worker before
// StreamSend has returned here.
status = Runtime().api->StreamSend(live, &request->buffer, 1,
finish ? QUIC_SEND_FLAG_FIN : QUIC_SEND_FLAG_NONE, request);
if (QUIC_SUCCEEDED(status)) return true;
std::lock_guard lk(mtx);
bytesInFlight -= request->bytes.size();
--sendsInFlight;
return false;
}
// A SendAsync that never reached msquic still reports, exactly once, but
// from a pool task: running it inside SendAsync would deadlock a caller
// that holds a lock its own callback takes.
static void FailSend(std::function<void(bool sent)> onSent) {
if (!onSent) return;
ThreadPool::Enqueue([onSent = std::move(onSent)] { onSent(false); });
}
// Up to `count` received bytes, waiting for them; fewer once the peer
// has closed its side and the rest is taken.
std::vector<char> TakeUpTo(std::uint32_t count) {
std::vector<char> out;
out.reserve(count);
std::unique_lock lk(mtx);
while (out.size() < count) {
cv.wait(lk, [&]{ return !pending.empty() || peerSendClosed || shutdownComplete; });
Take(out, count);
if (pending.empty() && (peerSendClosed || shutdownComplete)) break;
}
return out;
}
// Exactly `count` received bytes, once they have all arrived; nothing,
// leaving what did arrive where it is, once the peer has closed its side
// short of them. One hold of the lock throughout, so no other receive
// takes bytes from among them.
std::optional<std::vector<char>> TakeExactly(std::uint32_t count) {
std::unique_lock lk(mtx);
auto arrived = [&] {
std::size_t bytes = 0;
for (const std::vector<char>& chunk : pending) bytes += chunk.size();
return bytes;
};
cv.wait(lk, [&]{ return arrived() >= count || peerSendClosed || shutdownComplete; });
if (arrived() < count) return std::nullopt;
std::vector<char> out;
out.reserve(count);
Take(out, count);
return out;
}
// Moves pending bytes onto `out` until it holds `count`. Under mtx.
void Take(std::vector<char>& out, std::size_t count) {
while (!pending.empty() && out.size() < count) {
auto& chunk = pending.front();
std::size_t want = std::min<std::size_t>(chunk.size(), count - out.size());
out.insert(out.end(), chunk.begin(), chunk.begin() + want);
if (want == chunk.size()) {
pending.pop_front();
} else {
chunk.erase(chunk.begin(), chunk.begin() + want);
}
}
}
// Lifetime: msquic delivers stream callbacks (RECEIVE, SHUTDOWN_COMPLETE, …)
// possibly AFTER the owning QUICStream wrapper is destroyed (the wrapper only
// initiates a graceful shutdown; completion is async). To make that safe, the
// callback context is a heap `shared_ptr<Impl>*` (selfRef) that holds one
// strong ref; every callback copies it locally so the Impl stays alive for
// the callback's duration. The terminal SHUTDOWN_COMPLETE callback closes the
// stream and releases selfRef, after which the Impl is freed once the last
// ref (wrapper / in-flight callback copy) drops.
std::shared_ptr<Impl>* selfRef = nullptr;
// The owning connection's open-stream count. Incremented where the msquic
// handler is installed (QUICStream's handle constructor / OpenStream),
// decremented once the handle has been closed.
std::shared_ptr<StreamRegistry> registry;
// The connection's registry. Defined below ClientQUIC::Impl (which owns
// it); a member of QUICStream::Impl rather than a free function so it
// inherits QUICStream's friendship with ClientQUIC.
static std::shared_ptr<StreamRegistry> RegistryOf(ClientQUIC* connection);
// ---- msquic handle ownership ----------------------------------------
// StreamClose is "equivalent to free": any other msquic call on the handle
// that overlaps it is a use-after-free, which msquic reports as a bugcheck
// on whichever thread trips over the wreckage. The handle therefore has a
// refcount, and whoever drops the last ref closes it. There are two kinds
// of holder:
//
// - The msquic callback holds exactly one ref for the stream's lifetime,
// released by Retire() once SHUTDOWN_COMPLETE has been delivered (or by
// the OpenStream error paths, where no callback will ever run).
// - Every app thread inside an msquic call on the handle holds one for
// the duration of that call (AcquireHandle / ReleaseHandle).
//
// Without the second kind, a thread sending on a stream races the worker
// thread that closes it when the connection is torn down underneath —
// the shape any client with periodic acks or keepalives has.
std::mutex handleMtx;
HQUIC handle = nullptr; // cleared when the last ref lets go
int handleRefs = 1; // starts with the callback's ref
bool retired = false; // the callback's ref has been released
// The handle, valid until the matching ReleaseHandle; nullptr once the
// stream is retired, in which case do not call ReleaseHandle.
HQUIC AcquireHandle() {
std::lock_guard lk(handleMtx);
if (retired || !handle) return nullptr;
++handleRefs;
return handle;
}
void ReleaseHandle() {
HQUIC toClose = nullptr;
{
std::lock_guard lk(handleMtx);
if (--handleRefs > 0) return;
toClose = handle;
handle = nullptr;
}
// Last ref: nobody else can be inside an msquic call on this handle,
// and AcquireHandle will hand it out no more.
if (toClose) Runtime().api->StreamClose(toClose);
std::shared_ptr<StreamRegistry> reg = std::move(registry);
std::shared_ptr<Impl>* ref = selfRef;
selfRef = nullptr;
delete ref; // may destroy *this — touch no members past here
// Last of all: a destructor blocked in WaitForDrain may run
// ConnectionClose the moment this hits zero, and msquic wants every
// StreamClose on the connection to have happened first.
if (reg) reg->Remove();
}
// Publish the msquic handle. Called once, while the stream is still local
// to its constructor and no callback can run on it.
void SetHandle(HQUIC h) {
std::lock_guard lk(handleMtx);
handle = h;
}
// Release the callback's ref. Idempotent, so the SHUTDOWN_COMPLETE handler
// and an OpenStream error path can both call it without racing.
void Retire() {
{
std::lock_guard lk(handleMtx);
if (retired) return;
retired = true;
}
ReleaseHandle();
}
static QUIC_STATUS QUIC_API Callback(HQUIC stream, void* ctx, QUIC_STREAM_EVENT* ev) {
// Keep the Impl alive for the whole callback, even if the wrapper (and
// its ref) go away concurrently.
std::shared_ptr<Impl> keepAlive = *static_cast<std::shared_ptr<Impl>*>(ctx);
Impl* self = keepAlive.get();
switch (ev->Type) {
case QUIC_STREAM_EVENT_RECEIVE: {
std::vector<char> chunk;
std::uint64_t total = 0;
for (std::uint32_t i = 0; i < ev->RECEIVE.BufferCount; ++i) {
total += ev->RECEIVE.Buffers[i].Length;
}
chunk.reserve(static_cast<std::size_t>(total));
for (std::uint32_t i = 0; i < ev->RECEIVE.BufferCount; ++i) {
const QUIC_BUFFER& b = ev->RECEIVE.Buffers[i];
chunk.insert(chunk.end(), b.Buffer, b.Buffer + b.Length);
}
{
std::lock_guard lk(self->mtx);
if (!chunk.empty()) self->pending.push_back(std::move(chunk));
}
self->cv.notify_all();
return QUIC_STATUS_SUCCESS;
}
case QUIC_STREAM_EVENT_SEND_COMPLETE: {
auto* request = static_cast<SendRequest*>(ev->SEND_COMPLETE.ClientContext);
if (request == nullptr) return QUIC_STATUS_SUCCESS;
const bool sent = !ev->SEND_COMPLETE.Canceled;
{
std::lock_guard lk(self->mtx);
self->bytesInFlight -= request->bytes.size();
--self->sendsInFlight;
if (request->outcome) {
request->outcome->done = true;
request->outcome->sent = sent;
}
}
if (request->outcome) self->cv.notify_all();
std::function<void(bool)> onSent = std::move(request->onSent);
delete request;
// SendAsync's, here on the worker: msquic is done with the
// copy, and no thread was held while it had it.
if (onSent) onSent(sent);
return QUIC_STATUS_SUCCESS;
}
case QUIC_STREAM_EVENT_PEER_SEND_SHUTDOWN:
case QUIC_STREAM_EVENT_PEER_SEND_ABORTED: {
{
std::lock_guard lk(self->mtx);
self->peerSendClosed = true;
}
self->cv.notify_all();
return QUIC_STATUS_SUCCESS;
}
case QUIC_STREAM_EVENT_SHUTDOWN_COMPLETE: {
{
std::lock_guard lk(self->mtx);
self->peerSendClosed = true;
// Every send msquic took has had its SEND_COMPLETE by now;
// a SendSync still waiting is only woken to find out.
self->shutdownComplete = true;
}
self->cv.notify_all();
self->Retire();
return QUIC_STATUS_SUCCESS;
}
default:
return QUIC_STATUS_SUCCESS;
}
}
};
QUICStream::QUICStream() = default;
QUICStream::QUICStream(HQUIC handle, ClientQUIC* connection)
: handle(handle), connection(connection), impl(std::make_shared<Impl>())
{
impl->SetHandle(handle); // handleRefs already accounts for the callback
impl->connection = connection;
impl->registry = Impl::RegistryOf(connection);
if (impl->registry) impl->registry->Add();
impl->selfRef = new std::shared_ptr<Impl>(impl); // strong ref owned by the callback
Runtime().api->SetCallbackHandler(handle, reinterpret_cast<void*>(&Impl::Callback), impl->selfRef);
}
QUICStream::QUICStream(QUICStream&& other) noexcept
: handle(other.handle), connection(other.connection),
canSend(other.canSend), canReceive(other.canReceive),
impl(std::move(other.impl))
{
other.handle = nullptr;
other.connection = nullptr;
}
QUICStream& QUICStream::operator=(QUICStream&& other) noexcept {
if (this != &other) {
Stop();
handle = other.handle;
connection = other.connection;
canSend = other.canSend;
canReceive = other.canReceive;
impl = std::move(other.impl);
other.handle = nullptr;
other.connection = nullptr;
}
return *this;
}
QUICStream::~QUICStream() {
Stop();
}
void QUICStream::Stop() {
if (!handle) return;
handle = nullptr; // the wrapper is done with the stream either way
if (!impl) return;
// Only INITIATE the shutdown here; the async SHUTDOWN_COMPLETE callback
// releases the handle, and the Impl is a shared_ptr held by the callback's
// selfRef, so it safely outlives this wrapper until that callback runs.
// A null handle means SHUTDOWN_COMPLETE already fired and msquic has closed
// the stream — shutting it down again would be a use-after-free.
HQUIC live = impl->AcquireHandle();
if (!live) return;
// GRACEFUL closes our send direction only, and msquic rejects it combined
// with any other flag, so the receive direction needs a call of its own.
// Without it a bidirectional stream whose peer keeps its send side open
// never reaches SHUTDOWN_COMPLETE, so its handle is never closed and the
// connection can never finish tearing down.
Runtime().api->StreamShutdown(live, QUIC_STREAM_SHUTDOWN_FLAG_GRACEFUL, 0);
if (canReceive) {
Runtime().api->StreamShutdown(live, QUIC_STREAM_SHUTDOWN_FLAG_ABORT_RECEIVE, 0);
}
impl->ReleaseHandle();
}
void QUICStream::SendSync(const void* buffer, std::uint32_t size, bool finish) {
if (!handle || !canSend) throw QUICClosedException();
// Hold the handle across StreamSend: without this a connection torn down
// on another thread can close the stream between the check above and the
// call below, and msquic bugchecks on the freed handle.
HQUIC live = impl->AcquireHandle();
if (!live) throw QUICClosedException();
// This send's own outcome, not the stream's state. The flag this used to
// wait on was one per stream, and the wait then threw whenever the
// stream had finished shutting down by the time it woke: a peer that
// answered and finished the stream within a round trip, quicker than a
// busy machine wakes this thread, made a send that went out throw.
auto outcome = std::make_shared<Impl::SendOutcome>();
auto* request = new Impl::SendRequest(buffer, size);
request->outcome = outcome;
QUIC_STATUS s = QUIC_STATUS_SUCCESS;
const bool taken = impl->Send(live, request, finish, s);
impl->ReleaseHandle();
if (!taken) {
// No SEND_COMPLETE will arrive for a send msquic never took.
delete request;
throw QUICException(std::format("StreamSend failed: 0x{:x}", static_cast<unsigned>(s)));
}
std::unique_lock lk(impl->mtx);
// SEND_COMPLETE always precedes the stream's SHUTDOWN_COMPLETE; waking on
// the latter only keeps an msquic surprise from hanging this thread.
impl->cv.wait(lk, [&]{ return outcome->done || impl->shutdownComplete; });
if (!outcome->done || !outcome->sent) throw QUICClosedException();
}
std::vector<char> QUICStream::RecieveSync() {
if (!handle || !canReceive) throw QUICClosedException();
std::unique_lock lk(impl->mtx);
impl->cv.wait(lk, [&]{ return !impl->pending.empty() || impl->peerSendClosed || impl->shutdownComplete; });
if (!impl->pending.empty()) {
auto out = std::move(impl->pending.front());
impl->pending.pop_front();
return out;
}
throw QUICClosedException();
}
std::vector<char> QUICStream::RecieveUntilCloseSync() {
if (!handle || !canReceive) throw QUICClosedException();
std::vector<char> out;
while (true) {
std::unique_lock lk(impl->mtx);
impl->cv.wait(lk, [&]{ return !impl->pending.empty() || impl->peerSendClosed || impl->shutdownComplete; });
while (!impl->pending.empty()) {
auto& chunk = impl->pending.front();
out.insert(out.end(), chunk.begin(), chunk.end());
impl->pending.pop_front();
}
if (impl->peerSendClosed || impl->shutdownComplete) return out;
}
}
std::vector<char> QUICStream::RecieveUntilFullSync(std::uint32_t bufferSize) {
if (!handle || !canReceive) throw QUICClosedException();
// Closed early: what did arrive stays for the next receive.
std::optional<std::vector<char>> out = impl->TakeExactly(bufferSize);
if (!out) throw QUICClosedException();
return std::move(*out);
}
void QUICStream::SendAsync(const void* buffer, std::uint32_t size, bool finish,
std::function<void(bool sent)> onSent) {
// This used to be SendSync run as a pool task: a pool thread held for as
// long as msquic took to accept the buffer (a peer that reads slowly
// stretches that to its pace), and a task that reached back through
// `this`, so moving or destroying the wrapper before it ran was a
// use-after-free. Now the send goes to msquic here and its SEND_COMPLETE
// reports, on the worker. Only `impl` is read, not `handle`, which Stop()
// clears: SendAsync may run on another thread than the owner's, inside a
// callback, and a stopped stream refuses or cancels the send anyway.
HQUIC live = impl && canSend ? impl->AcquireHandle() : nullptr;
if (live == nullptr) {
Impl::FailSend(std::move(onSent));
return;
}
auto* request = new Impl::SendRequest(buffer, size);
request->onSent = std::move(onSent);
QUIC_STATUS status = QUIC_STATUS_SUCCESS;
const bool taken = impl->Send(live, request, finish, status);
impl->ReleaseHandle();
if (!taken) {
std::function<void(bool)> callback = std::move(request->onSent);
delete request;
Impl::FailSend(std::move(callback));
}
}
std::uint64_t QUICStream::BytesInFlight() const {
if (!impl) return 0;
std::lock_guard lk(impl->mtx);
return impl->bytesInFlight;
}
std::size_t QUICStream::SendsInFlight() const {
if (!impl) return 0;
std::lock_guard lk(impl->mtx);
return impl->sendsInFlight;
}
// The async receives deliver a closed stream as the browser build does: an
// empty chunk, as nothing may leave a pool task.
void QUICStream::RecieveAsync(std::function<void(std::vector<char>)> cb) {
ThreadPool::Enqueue([this, cb]{
std::vector<char> chunk;
try {
chunk = this->RecieveSync();
} catch (const QUICClosedException&) {}
cb(std::move(chunk));
});
}
void QUICStream::RecieveUntilCloseAsync(std::function<void(std::vector<char>)> cb) {
ThreadPool::Enqueue([this, cb]{
std::vector<char> data;
try {
data = this->RecieveUntilCloseSync();
} catch (const QUICClosedException&) {}
cb(std::move(data));
});
}
void QUICStream::RecieveUntilFullAsync(std::uint32_t bufferSize, std::function<void(std::vector<char>)> cb) {
ThreadPool::Enqueue([this, bufferSize, cb]{
cb(handle && canReceive ? impl->TakeUpTo(bufferSize) : std::vector<char>{});
});
}
void QUICStream::PrependReceived(std::vector<char> bytes) {
if (bytes.empty() || !impl) return;
{
std::lock_guard lk(impl->mtx);
impl->pending.push_front(std::move(bytes));
}
impl->cv.notify_all();
}
std::uint64_t QUICStream::GetStreamId() const {
if (!handle) throw QUICException("GetStreamId: stream is not open");
// GetParam blocks on the connection's msquic worker, so it must not be the
// worker that waits for us — hence a refcount rather than an exclusion
// lock: SHUTDOWN_COMPLETE just drops its ref and returns.
HQUIC live = impl->AcquireHandle();
if (!live) throw QUICException("GetStreamId: stream is not open");
QUIC_UINT62 id = 0;
std::uint32_t size = sizeof(id);
QUIC_STATUS s = Runtime().api->GetParam(live, QUIC_PARAM_STREAM_ID, &size, &id);
impl->ReleaseHandle();
if (QUIC_FAILED(s)) {
throw QUICException(std::format("GetParam(QUIC_PARAM_STREAM_ID) failed: 0x{:x}",
static_cast<unsigned>(s)));
}
return static_cast<std::uint64_t>(id);
}
// ---------------- ClientQUIC::Impl ----------------
struct ClientQUIC::Impl {
HQUIC connection = nullptr;
HQUIC configuration = nullptr;
bool ownsConfiguration = true;
std::mutex mtx;
std::condition_variable cv;
bool connected = false;
bool closed = false;
bool shutdownComplete = false; // msquic delivered SHUTDOWN_COMPLETE
QUIC_STATUS shutdownStatus = QUIC_STATUS_SUCCESS;
std::function<void(QUICStream)> onStream;
std::function<void(std::vector<char>)> onDatagram;
std::deque<std::vector<char>> datagramQueue;
// Streams the peer started before the user installed an OnStream
// handler. Without this backlog the early streams (e.g. an h3 server's
// control stream right after handshake) would be aborted in the
// PEER_STREAM_STARTED branch and the connection would die with
// H3_MISSING_SETTINGS on the peer side.
std::deque<QUICStream> pendingStreams;
// Streams currently open on this connection. Shared with each QUICStream
// so the count survives a stream that outlives us.
std::shared_ptr<StreamRegistry> streams = std::make_shared<StreamRegistry>();
// OnClosed's callback and the state that decides whether it runs.
std::shared_ptr<CloseNotice> closeNotice = std::make_shared<CloseNotice>();
ClientQUIC* outer = nullptr;
// Take the connection handle away from whoever else might close it.
// `connection` is the single owner token: exactly one of ~ClientQUIC and
// the SHUTDOWN_COMPLETE callback wins the claim, and only the winner calls
// ConnectionClose. Without this the two race and msquic bugchecks on the
// second close (CXPLAT_TEL_ASSERT(!Connection->State.HandleClosed)).
HQUIC ClaimConnection() {
std::lock_guard lk(mtx);
HQUIC claimed = connection;
connection = nullptr;
return claimed;
}
// Shut the connection down and close it, waiting (bounded) for every
// stream on it to reach StreamClose first, and then for the shutdown to
// complete, so the peer is told. No-op if someone else already claimed
// the handle. Never holds `mtx` across an msquic call: the connection
// callback takes it too.
void CloseConnection() {
HQUIC claimed = ClaimConnection();
if (!claimed) return;
// Aborts any stream still open; each one's SHUTDOWN_COMPLETE runs
// Retire, which closes it and drops the count below.
Runtime().api->ConnectionShutdown(claimed, QUIC_CONNECTION_SHUTDOWN_FLAG_NONE, 0);
streams->WaitForDrain(streamDrainTimeout);
{
// See closeNotifyTimeout. The SHUTDOWN_COMPLETE handler sets the
// flag before it looks at the handle, which we hold, so it leaves
// the close to us.
std::unique_lock lk(mtx);
cv.wait_for(lk, closeNotifyTimeout, [&] { return shutdownComplete; });
}
Runtime().api->ConnectionClose(claimed);
}
static QUIC_STATUS QUIC_API Callback(HQUIC conn, void* ctx, QUIC_CONNECTION_EVENT* ev) {
auto* self = static_cast<Impl*>(ctx);
switch (ev->Type) {
case QUIC_CONNECTION_EVENT_CONNECTED: {
{
std::lock_guard lk(self->mtx);
self->connected = true;
}
self->cv.notify_all();
return QUIC_STATUS_SUCCESS;
}
case QUIC_CONNECTION_EVENT_SHUTDOWN_INITIATED_BY_TRANSPORT:
case QUIC_CONNECTION_EVENT_SHUTDOWN_INITIATED_BY_PEER: {
{
std::lock_guard lk(self->mtx);
self->closed = true;
if (ev->Type == QUIC_CONNECTION_EVENT_SHUTDOWN_INITIATED_BY_TRANSPORT) {
self->shutdownStatus = ev->SHUTDOWN_INITIATED_BY_TRANSPORT.Status;
}
}
self->cv.notify_all();
return QUIC_STATUS_SUCCESS;
}
case QUIC_CONNECTION_EVENT_SHUTDOWN_COMPLETE: {
{
std::lock_guard lk(self->mtx);
self->closed = true;
self->shutdownComplete = true;
}
self->cv.notify_all();
// AppCloseInProgress means ~ClientQUIC is already inside
// ConnectionClose; otherwise close the handle here so a
// connection dropped by the peer does not leak while the
// owning ClientQUIC lives on. Claiming the handle settles which
// of the two actually does it. Every stream msquic knew of was
// aborted at the first close (QuicConnTryClose), so each has
// had its own SHUTDOWN_COMPLETE before this one.
if (ev->SHUTDOWN_COMPLETE.AppCloseInProgress != 0) return QUIC_STATUS_SUCCESS;
std::shared_ptr<CloseNotice> notice;
{
// The claim and the notice together, so ~ClientQUIC
// cannot slip between them.
std::lock_guard lk(self->mtx);
if (self->connection == nullptr) return QUIC_STATUS_SUCCESS;
self->connection = nullptr;
notice = self->closeNotice;
}
Runtime().api->ConnectionClose(conn);
// Nothing of `self` from here on: ~ClientQUIC, finding no
// handle to claim, does not wait for this worker, and the
// OnClosed callback may well be what deletes it.
{
std::lock_guard lk(notice->mtx);
notice->closed = true;
}
CloseNotice::Fire(notice);
return QUIC_STATUS_SUCCESS;
}
case QUIC_CONNECTION_EVENT_PEER_STREAM_STARTED: {
HQUIC streamHandle = ev->PEER_STREAM_STARTED.Stream;
bool unidirectional = (ev->PEER_STREAM_STARTED.Flags
& QUIC_STREAM_OPEN_FLAG_UNIDIRECTIONAL) != 0;
QUICStream stream(streamHandle, self->outer);
if (unidirectional) {
// Peer-initiated unidi: peer sends, we read; we cannot send.
stream.canSend = false;
stream.canReceive = true;
}
std::function<void(QUICStream)> cb;
{
std::lock_guard lk(self->mtx);
cb = self->onStream;
if (!cb) {
// Buffer until OnStream is installed; OnStream's
// setter drains this queue.
self->pendingStreams.push_back(std::move(stream));
return QUIC_STATUS_SUCCESS;
}
}
auto* shared = new QUICStream(std::move(stream));
ThreadPool::Enqueue([cb, shared]{
cb(std::move(*shared));
delete shared;
});
return QUIC_STATUS_SUCCESS;
}
case QUIC_CONNECTION_EVENT_DATAGRAM_RECEIVED: {
std::vector<char> chunk(ev->DATAGRAM_RECEIVED.Buffer->Buffer,
ev->DATAGRAM_RECEIVED.Buffer->Buffer + ev->DATAGRAM_RECEIVED.Buffer->Length);
if (self->onDatagram) {
auto cb = self->onDatagram;
ThreadPool::Enqueue([cb, chunk = std::move(chunk)]() mutable { cb(std::move(chunk)); });
} else {
std::lock_guard lk(self->mtx);
self->datagramQueue.push_back(std::move(chunk));
self->cv.notify_all();
}
return QUIC_STATUS_SUCCESS;
}
case QUIC_CONNECTION_EVENT_DATAGRAM_SEND_STATE_CHANGED: {
// msquic fires this event multiple times per datagram (e.g.
// SENT -> ACKNOWLEDGED). Free the combined QUIC_BUFFER+payload
// allocation only on a terminal state — SENT and LOST_SUSPECT
// are intermediate and may be followed by another transition.
auto state = ev->DATAGRAM_SEND_STATE_CHANGED.State;
if (ev->DATAGRAM_SEND_STATE_CHANGED.ClientContext &&
(state == QUIC_DATAGRAM_SEND_LOST_DISCARDED
|| state == QUIC_DATAGRAM_SEND_ACKNOWLEDGED
|| state == QUIC_DATAGRAM_SEND_ACKNOWLEDGED_SPURIOUS
|| state == QUIC_DATAGRAM_SEND_CANCELED)) {
::operator delete(ev->DATAGRAM_SEND_STATE_CHANGED.ClientContext);
}
return QUIC_STATUS_SUCCESS;
}
default:
return QUIC_STATUS_SUCCESS;
}
}
};
static HQUIC OpenClientConfiguration(const std::string& alpn, const QUICClientCredentials& creds) {
std::vector<std::uint8_t> alpnBuf;
QUIC_BUFFER alpnBuffer = MakeAlpn(alpn, alpnBuf);
QUIC_SETTINGS settings{};
settings.IsSet.IdleTimeoutMs = 1;
settings.IdleTimeoutMs = creds.settings.idleTimeoutMs;
settings.IsSet.HandshakeIdleTimeoutMs = 1;
settings.HandshakeIdleTimeoutMs = creds.settings.handshakeIdleTimeoutMs;
// Keep the connection alive across long idle gaps. msquic sends PING frames
// on its own timer thread (independent of the app), so a request/response
// connection survives even while the app is blocked for a long time between
// requests (e.g. a client waiting on slow LLM inference). Interval < idle
// timeout so the peer's idle timer never expires.
settings.IsSet.KeepAliveIntervalMs = 1;
settings.KeepAliveIntervalMs = creds.settings.keepAliveIntervalMs;
settings.IsSet.DatagramReceiveEnabled = 1;
settings.DatagramReceiveEnabled = creds.settings.datagramReceiveEnabled ? 1 : 0;
// Allow the server to open unidi/bidi streams to us. msquic defaults
// both peer-stream-count limits to 0; with that, the server's HTTP/3
// control stream + QPACK encoder/decoder streams can't be created and
// most h3 servers will close the connection after handshake. We don't
// currently use server push (h3 pushes ride on unidi 0x01 streams) but
// the bidi cap is harmless to grant.
settings.IsSet.PeerUnidiStreamCount = 1;
settings.PeerUnidiStreamCount = creds.settings.peerUnidiStreamCount;
settings.IsSet.PeerBidiStreamCount = 1;
settings.PeerBidiStreamCount = creds.settings.peerBidiStreamCount;
HQUIC cfg = nullptr;
QUIC_STATUS s = Runtime().api->ConfigurationOpen(Runtime().registration, &alpnBuffer, 1,
&settings, sizeof(settings), nullptr, &cfg);
if (QUIC_FAILED(s)) throw QUICException(std::format("ConfigurationOpen failed: 0x{:x}", static_cast<unsigned>(s)));
QUIC_CREDENTIAL_CONFIG cc{};
cc.Type = QUIC_CREDENTIAL_TYPE_NONE;
cc.Flags = QUIC_CREDENTIAL_FLAG_CLIENT;
if (creds.insecureNoServerValidation) {
cc.Flags |= QUIC_CREDENTIAL_FLAG_NO_CERTIFICATE_VALIDATION;
}
s = Runtime().api->ConfigurationLoadCredential(cfg, &cc);
if (QUIC_FAILED(s)) {
Runtime().api->ConfigurationClose(cfg);
throw QUICException(std::format("ConfigurationLoadCredential failed: 0x{:x}", static_cast<unsigned>(s)));
}
return cfg;
}
ClientQUIC::ClientQUIC(const char* host, std::uint16_t port, std::string alpnIn,
QUICClientCredentials creds)
: alpn(std::move(alpnIn)), impl(std::make_unique<Impl>())
{
impl->outer = this;
impl->configuration = OpenClientConfiguration(alpn, creds);
QUIC_STATUS s = Runtime().api->ConnectionOpen(Runtime().registration,
reinterpret_cast<QUIC_CONNECTION_CALLBACK_HANDLER>(&Impl::Callback),
impl.get(), &impl->connection);
if (QUIC_FAILED(s)) {
Runtime().api->ConfigurationClose(impl->configuration);
throw QUICException(std::format("ConnectionOpen failed: 0x{:x}", static_cast<unsigned>(s)));
}
s = Runtime().api->ConnectionStart(impl->connection, impl->configuration, QUIC_ADDRESS_FAMILY_UNSPEC, host, port);
if (QUIC_FAILED(s)) {
Runtime().api->ConnectionClose(impl->connection);
Runtime().api->ConfigurationClose(impl->configuration);
throw QUICException(std::format("ConnectionStart failed: 0x{:x}", static_cast<unsigned>(s)));
}
QUIC_STATUS handshakeStatus = QUIC_STATUS_SUCCESS;
{
std::unique_lock lk(impl->mtx);
// Bounded by HandshakeIdleTimeoutMs above: an unreachable peer ends in
// SHUTDOWN_INITIATED_BY_TRANSPORT rather than waiting here forever.
impl->cv.wait(lk, [&]{ return impl->connected || impl->closed; });
if (impl->connected) return;
handshakeStatus = impl->shutdownStatus;
}
// Throwing from here means ~ClientQUIC never runs, so tear the msquic
// handles down by hand — the connection callback holds `impl`, which is
// about to be destroyed with the half-built object.
impl->CloseConnection();
Runtime().api->ConfigurationClose(impl->configuration);
impl->configuration = nullptr;
throw QUICException(std::format("QUIC handshake failed: 0x{:x}",
static_cast<unsigned>(handshakeStatus)));
}
ClientQUIC::ClientQUIC(std::string host, std::uint16_t port, std::string alpnIn, QUICClientCredentials creds)
: ClientQUIC(host.c_str(), port, std::move(alpnIn), std::move(creds)) {}
ClientQUIC::ClientQUIC(HQUIC connectionHandle, HQUIC serverConfiguration, std::string alpnIn)
: alpn(std::move(alpnIn)), impl(std::make_unique<Impl>())
{
impl->outer = this;
impl->connection = connectionHandle;
impl->configuration = serverConfiguration;
impl->ownsConfiguration = false;
impl->connected = true;
Runtime().api->SetCallbackHandler(connectionHandle,
reinterpret_cast<void*>(&Impl::Callback),
impl.get());
}
ClientQUIC::ClientQUIC(ClientQUIC&& other) noexcept
: alpn(std::move(other.alpn)), impl(std::move(other.impl))
{
if (impl) impl->outer = this;
}
ClientQUIC::~ClientQUIC() {
if (!impl) return;
// First of all: the OnClosed callback must not start once the owner has
// begun destroying the connection, and one running on another thread
// has to be done with it before it goes. A callback that is deleting
// this very object runs on this thread and is not waited for; it already
// closed the handle, so CloseConnection below finds nothing to claim and
// returns at once.
impl->closeNotice->OwnerGone();
// Before the connection goes: streams the peer started that no OnStream
// handler ever claimed. Destroying them here rather than with the rest of
// `impl` keeps every stream teardown ahead of ConnectionClose, so the
// drain below actually covers them.
{
std::deque<QUICStream> backlog;
{
std::lock_guard lk(impl->mtx);
std::swap(backlog, impl->pendingStreams);
}
}
impl->CloseConnection();
if (impl->configuration && impl->ownsConfiguration) {
Runtime().api->ConfigurationClose(impl->configuration);
impl->configuration = nullptr;
}
}
void ClientQUIC::Stop() {
if (!impl) return;
// Read the handle under the lock: the SHUTDOWN_COMPLETE callback may be
// closing the connection concurrently on an msquic worker.
HQUIC conn = nullptr;
{
std::lock_guard lk(impl->mtx);
conn = impl->connection;
}
if (conn) Runtime().api->ConnectionShutdown(conn, QUIC_CONNECTION_SHUTDOWN_FLAG_NONE, 0);
}
QUICStream ClientQUIC::OpenStream(bool unidirectional) {
HQUIC streamHandle = nullptr;
QUICStream stream;
stream.impl = std::make_shared<QUICStream::Impl>();
stream.impl->connection = this;
// Count the stream as open before StreamOpen registers the callback, so a
// callback can never observe a half-initialised Impl. The two failure
// paths below undo it.
stream.impl->registry = impl->streams;
stream.impl->registry->Add();
stream.impl->selfRef = new std::shared_ptr<QUICStream::Impl>(stream.impl);
QUIC_STREAM_OPEN_FLAGS openFlags = unidirectional
? QUIC_STREAM_OPEN_FLAG_UNIDIRECTIONAL
: QUIC_STREAM_OPEN_FLAG_NONE;
QUIC_STATUS s = Runtime().api->StreamOpen(impl->connection, openFlags,
reinterpret_cast<QUIC_STREAM_CALLBACK_HANDLER>(&QUICStream::Impl::Callback),
stream.impl->selfRef, &streamHandle);
if (QUIC_FAILED(s)) {
delete stream.impl->selfRef;
stream.impl->selfRef = nullptr;
// No msquic stream exists, so there is no handle to release.
std::shared_ptr<StreamRegistry> registry = std::move(stream.impl->registry);
registry->Remove();
throw QUICException(std::format("StreamOpen failed: 0x{:x}", static_cast<unsigned>(s)));
}
stream.handle = streamHandle;
stream.connection = this;
stream.impl->SetHandle(streamHandle);
if (unidirectional) {
// We initiated the unidi stream: we send, peer reads.
stream.canSend = true;
stream.canReceive = false;
}
// SHUTDOWN_ON_FAIL, not NONE. StreamStart is asynchronous — it returns
// QUIC_STATUS_PENDING and queues the start onto the connection — so it can
// still fail later, and it does exactly that (QUIC_STATUS_INVALID_STATE)
// whenever the connection is shut down before the queued start runs. That
// is an everyday race for a client that sends periodically: opening a
// stream just as the connection goes away. Without this flag msquic leaves
// such a stream neither started nor shut down, so SHUTDOWN_COMPLETE never
// arrives, the handle is never closed, and the registration's rundown at
// exit() blocks forever waiting for it. With it, the failed start is
// followed by SHUTDOWN_COMPLETE like any other stream.
s = Runtime().api->StreamStart(streamHandle, QUIC_STREAM_START_FLAG_SHUTDOWN_ON_FAIL);
if (QUIC_FAILED(s)) {
// Synchronous failure: the stream never started, so no callback will
// ever run. Release the callback's ref by hand, which closes the
// handle, and clear the wrapper's so ~QUICStream is a no-op.
stream.handle = nullptr;
stream.impl->Retire();
throw QUICException(std::format("StreamStart failed: 0x{:x}", static_cast<unsigned>(s)));
}
return stream;
}
void ClientQUIC::SendDatagram(const void* buffer, std::uint32_t size) {
// msquic stores the QUIC_BUFFER pointer (not a copy) on the send queue
// and serialises async on a worker thread. Both the QUIC_BUFFER and the
// payload it points at must outlive the call until DATAGRAM_SEND_STATE
// reports a terminal state. Pack them together in a single allocation.
auto* mem = static_cast<std::uint8_t*>(::operator new(sizeof(QUIC_BUFFER) + size));
auto* hdr = reinterpret_cast<QUIC_BUFFER*>(mem);
auto* payload = mem + sizeof(QUIC_BUFFER);
std::memcpy(payload, buffer, size);
hdr->Buffer = payload;
hdr->Length = size;
QUIC_STATUS s = Runtime().api->DatagramSend(impl->connection, hdr, 1,
QUIC_SEND_FLAG_NONE, mem);
if (QUIC_FAILED(s)) {
::operator delete(mem);
throw QUICException(std::format("DatagramSend failed: 0x{:x}", static_cast<unsigned>(s)));
}
}
void ClientQUIC::OnStream(std::function<void(QUICStream)> cb) {
std::deque<QUICStream> backlog;
{
std::lock_guard lk(impl->mtx);
impl->onStream = cb;
std::swap(backlog, impl->pendingStreams);
}
while (!backlog.empty()) {
auto* shared = new QUICStream(std::move(backlog.front()));
backlog.pop_front();
auto handler = cb;
ThreadPool::Enqueue([handler, shared]{
handler(std::move(*shared));
delete shared;
});
}
}
void ClientQUIC::OnDatagram(std::function<void(std::vector<char>)> cb) {
impl->onDatagram = std::move(cb);
}
void ClientQUIC::OnClosed(std::function<void()> callback) {
if (!impl) return;
const std::shared_ptr<CloseNotice> notice = impl->closeNotice;
bool due = false;
{
std::lock_guard lk(notice->mtx);
if (notice->fired) return;
// The one replaced is destroyed outside the lock, with `callback`.
callback.swap(notice->callback);
due = notice->closed && notice->callback;
}
// Closed already, typically before a ListenerQUIC's connectCallback got
// to run: fire from the pool, never from in here, where the caller is
// still using the object the callback is likely to delete. Fire checks
// again, so a second OnClosed racing this one cannot fire it twice.
if (due) ThreadPool::Enqueue([notice] { CloseNotice::Fire(notice); });
}
std::vector<char> ClientQUIC::RecieveDatagramSync() {
std::unique_lock lk(impl->mtx);
impl->cv.wait(lk, [&]{ return !impl->datagramQueue.empty() || impl->closed; });
if (!impl->datagramQueue.empty()) {
auto out = std::move(impl->datagramQueue.front());
impl->datagramQueue.pop_front();
return out;
}
throw QUICClosedException();
}
HQUIC ClientQUIC::GetHandle() const { return impl ? impl->connection : nullptr; }
std::shared_ptr<StreamRegistry> QUICStream::Impl::RegistryOf(ClientQUIC* connection) {
if (!connection || !connection->impl) return nullptr;
return connection->impl->streams;
}