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/*
* Copyright 2020 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "pc/sctp_data_channel.h"
#include <limits>
#include <memory>
#include <string>
#include <utility>
#include "api/priority.h"
#include "media/sctp/sctp_transport_internal.h"
#include "pc/proxy.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/system/unused.h"
#include "rtc_base/thread.h"
namespace webrtc {
namespace {
static size_t kMaxQueuedReceivedDataBytes = 16 * 1024 * 1024;
static std::atomic<int> g_unique_id{0};
int GenerateUniqueId() {
return ++g_unique_id;
}
// Define proxy for DataChannelInterface.
BEGIN_PROXY_MAP(DataChannel)
PROXY_PRIMARY_THREAD_DESTRUCTOR()
BYPASS_PROXY_METHOD1(void, RegisterObserver, DataChannelObserver*)
BYPASS_PROXY_METHOD0(void, UnregisterObserver)
BYPASS_PROXY_CONSTMETHOD0(std::string, label)
BYPASS_PROXY_CONSTMETHOD0(bool, reliable)
BYPASS_PROXY_CONSTMETHOD0(bool, ordered)
BYPASS_PROXY_CONSTMETHOD0(uint16_t, maxRetransmitTime)
BYPASS_PROXY_CONSTMETHOD0(uint16_t, maxRetransmits)
BYPASS_PROXY_CONSTMETHOD0(absl::optional<int>, maxRetransmitsOpt)
BYPASS_PROXY_CONSTMETHOD0(absl::optional<int>, maxPacketLifeTime)
BYPASS_PROXY_CONSTMETHOD0(std::string, protocol)
BYPASS_PROXY_CONSTMETHOD0(bool, negotiated)
// Can't bypass the proxy since the id may change.
PROXY_SECONDARY_CONSTMETHOD0(int, id)
BYPASS_PROXY_CONSTMETHOD0(PriorityValue, priority)
BYPASS_PROXY_CONSTMETHOD0(DataState, state)
BYPASS_PROXY_CONSTMETHOD0(RTCError, error)
PROXY_SECONDARY_CONSTMETHOD0(uint32_t, messages_sent)
PROXY_SECONDARY_CONSTMETHOD0(uint64_t, bytes_sent)
PROXY_SECONDARY_CONSTMETHOD0(uint32_t, messages_received)
PROXY_SECONDARY_CONSTMETHOD0(uint64_t, bytes_received)
PROXY_SECONDARY_CONSTMETHOD0(uint64_t, buffered_amount)
PROXY_SECONDARY_METHOD0(void, Close)
PROXY_SECONDARY_METHOD1(bool, Send, const DataBuffer&)
BYPASS_PROXY_METHOD2(void,
SendAsync,
DataBuffer,
absl::AnyInvocable<void(RTCError) &&>)
END_PROXY_MAP(DataChannel)
} // namespace
InternalDataChannelInit::InternalDataChannelInit(const DataChannelInit& base)
: DataChannelInit(base), open_handshake_role(kOpener) {
// If the channel is externally negotiated, do not send the OPEN message.
if (base.negotiated) {
open_handshake_role = kNone;
} else {
// Datachannel is externally negotiated. Ignore the id value.
// Specified in createDataChannel, WebRTC spec section 6.1 bullet 13.
id = -1;
}
// Backwards compatibility: If maxRetransmits or maxRetransmitTime
// are negative, the feature is not enabled.
// Values are clamped to a 16bit range.
if (maxRetransmits) {
if (*maxRetransmits < 0) {
RTC_LOG(LS_ERROR)
<< "Accepting maxRetransmits < 0 for backwards compatibility";
maxRetransmits = absl::nullopt;
} else if (*maxRetransmits > std::numeric_limits<uint16_t>::max()) {
maxRetransmits = std::numeric_limits<uint16_t>::max();
}
}
if (maxRetransmitTime) {
if (*maxRetransmitTime < 0) {
RTC_LOG(LS_ERROR)
<< "Accepting maxRetransmitTime < 0 for backwards compatibility";
maxRetransmitTime = absl::nullopt;
} else if (*maxRetransmitTime > std::numeric_limits<uint16_t>::max()) {
maxRetransmitTime = std::numeric_limits<uint16_t>::max();
}
}
}
bool InternalDataChannelInit::IsValid() const {
if (id < -1)
return false;
if (maxRetransmits.has_value() && maxRetransmits.value() < 0)
return false;
if (maxRetransmitTime.has_value() && maxRetransmitTime.value() < 0)
return false;
// Only one of these can be set.
if (maxRetransmits.has_value() && maxRetransmitTime.has_value())
return false;
return true;
}
absl::optional<StreamId> SctpSidAllocator::AllocateSid(rtc::SSLRole role) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
int potential_sid = (role == rtc::SSL_CLIENT) ? 0 : 1;
while (potential_sid <= static_cast<int>(cricket::kMaxSctpSid)) {
StreamId sid(potential_sid);
if (used_sids_.insert(sid).second)
return sid;
potential_sid += 2;
}
RTC_LOG(LS_ERROR) << "SCTP sid allocation pool exhausted.";
return absl::nullopt;
}
bool SctpSidAllocator::ReserveSid(StreamId sid) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
return used_sids_.insert(sid).second;
}
void SctpSidAllocator::ReleaseSid(StreamId sid) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
used_sids_.erase(sid);
}
// A DataChannelObserver implementation that offers backwards compatibility with
// implementations that aren't yet ready to be called back on the network
// thread. This implementation posts events to the signaling thread where
// events are delivered.
// In the class, and together with the `SctpDataChannel` implementation, there's
// special handling for the `state()` property whereby if that property is
// queried on the channel object while inside an event callback, we return
// the state that was active at the time the event was issued. This is to avoid
// a problem with calling the `state()` getter on the proxy, which would do
// a blocking call to the network thread, effectively flushing operations on
// the network thread that could cause the state to change and eventually return
// a misleading or arguably, wrong, state value to the callback implementation.
// As a future improvement to the ObserverAdapter, we could do the same for
// other properties that need to be read on the network thread. Eventually
// all implementations should expect to be called on the network thread though
// and the ObserverAdapter no longer be necessary.
class SctpDataChannel::ObserverAdapter : public DataChannelObserver {
public:
explicit ObserverAdapter(
SctpDataChannel* channel,
rtc::scoped_refptr<PendingTaskSafetyFlag> signaling_safety)
: channel_(channel), signaling_safety_(std::move(signaling_safety)) {}
bool IsInsideCallback() const {
RTC_DCHECK_RUN_ON(signaling_thread());
return cached_getters_ != nullptr;
}
DataChannelInterface::DataState cached_state() const {
RTC_DCHECK_RUN_ON(signaling_thread());
RTC_DCHECK(IsInsideCallback());
return cached_getters_->state();
}
RTCError cached_error() const {
RTC_DCHECK_RUN_ON(signaling_thread());
RTC_DCHECK(IsInsideCallback());
return cached_getters_->error();
}
void SetDelegate(DataChannelObserver* delegate) {
RTC_DCHECK_RUN_ON(signaling_thread());
delegate_ = delegate;
safety_.reset(PendingTaskSafetyFlag::CreateDetached());
}
static void DeleteOnSignalingThread(
std::unique_ptr<ObserverAdapter> observer) {
auto* signaling_thread = observer->signaling_thread();
if (!signaling_thread->IsCurrent())
signaling_thread->PostTask([observer = std::move(observer)]() {});
}
private:
class CachedGetters {
public:
explicit CachedGetters(ObserverAdapter* adapter)
: adapter_(adapter),
cached_state_(adapter_->channel_->state()),
cached_error_(adapter_->channel_->error()) {
RTC_DCHECK_RUN_ON(adapter->network_thread());
}
~CachedGetters() {
if (!was_dropped_) {
RTC_DCHECK_RUN_ON(adapter_->signaling_thread());
RTC_DCHECK_EQ(adapter_->cached_getters_, this);
adapter_->cached_getters_ = nullptr;
}
}
bool PrepareForCallback() {
RTC_DCHECK_RUN_ON(adapter_->signaling_thread());
RTC_DCHECK(was_dropped_);
was_dropped_ = false;
adapter_->cached_getters_ = this;
return adapter_->delegate_ && adapter_->signaling_safety_->alive();
}
RTCError error() { return cached_error_; }
DataChannelInterface::DataState state() { return cached_state_; }
private:
ObserverAdapter* const adapter_;
bool was_dropped_ = true;
const DataChannelInterface::DataState cached_state_;
const RTCError cached_error_;
};
void OnStateChange() override {
RTC_DCHECK_RUN_ON(network_thread());
signaling_thread()->PostTask(
SafeTask(safety_.flag(),
[this, cached_state = std::make_unique<CachedGetters>(this)] {
RTC_DCHECK_RUN_ON(signaling_thread());
if (cached_state->PrepareForCallback())
delegate_->OnStateChange();
}));
}
void OnMessage(const DataBuffer& buffer) override {
RTC_DCHECK_RUN_ON(network_thread());
signaling_thread()->PostTask(SafeTask(
safety_.flag(), [this, buffer = buffer,
cached_state = std::make_unique<CachedGetters>(this)] {
RTC_DCHECK_RUN_ON(signaling_thread());
if (cached_state->PrepareForCallback())
delegate_->OnMessage(buffer);
}));
}
void OnBufferedAmountChange(uint64_t sent_data_size) override {
RTC_DCHECK_RUN_ON(network_thread());
signaling_thread()->PostTask(SafeTask(
safety_.flag(), [this, sent_data_size,
cached_state = std::make_unique<CachedGetters>(this)] {
RTC_DCHECK_RUN_ON(signaling_thread());
if (cached_state->PrepareForCallback())
delegate_->OnBufferedAmountChange(sent_data_size);
}));
}
bool IsOkToCallOnTheNetworkThread() override { return true; }
rtc::Thread* signaling_thread() const { return signaling_thread_; }
rtc::Thread* network_thread() const { return channel_->network_thread_; }
DataChannelObserver* delegate_ RTC_GUARDED_BY(signaling_thread()) = nullptr;
SctpDataChannel* const channel_;
// Make sure to keep our own signaling_thread_ pointer to avoid dereferencing
// `channel_` in the `RTC_DCHECK_RUN_ON` checks on the signaling thread.
rtc::Thread* const signaling_thread_{channel_->signaling_thread_};
ScopedTaskSafety safety_;
rtc::scoped_refptr<PendingTaskSafetyFlag> signaling_safety_;
CachedGetters* cached_getters_ RTC_GUARDED_BY(signaling_thread()) = nullptr;
};
// static
rtc::scoped_refptr<SctpDataChannel> SctpDataChannel::Create(
rtc::WeakPtr<SctpDataChannelControllerInterface> controller,
const std::string& label,
bool connected_to_transport,
const InternalDataChannelInit& config,
rtc::Thread* signaling_thread,
rtc::Thread* network_thread) {
RTC_DCHECK(config.IsValid());
return rtc::make_ref_counted<SctpDataChannel>(
config, std::move(controller), label, connected_to_transport,
signaling_thread, network_thread);
}
// static
rtc::scoped_refptr<DataChannelInterface> SctpDataChannel::CreateProxy(
rtc::scoped_refptr<SctpDataChannel> channel,
rtc::scoped_refptr<PendingTaskSafetyFlag> signaling_safety) {
// Copy thread params to local variables before `std::move()`.
auto* signaling_thread = channel->signaling_thread_;
auto* network_thread = channel->network_thread_;
channel->observer_adapter_ = std::make_unique<ObserverAdapter>(
channel.get(), std::move(signaling_safety));
return DataChannelProxy::Create(signaling_thread, network_thread,
std::move(channel));
}
SctpDataChannel::SctpDataChannel(
const InternalDataChannelInit& config,
rtc::WeakPtr<SctpDataChannelControllerInterface> controller,
const std::string& label,
bool connected_to_transport,
rtc::Thread* signaling_thread,
rtc::Thread* network_thread)
: signaling_thread_(signaling_thread),
network_thread_(network_thread),
id_n_(config.id == -1 ? absl::nullopt : absl::make_optional(config.id)),
internal_id_(GenerateUniqueId()),
label_(label),
protocol_(config.protocol),
max_retransmit_time_(config.maxRetransmitTime),
max_retransmits_(config.maxRetransmits),
priority_(config.priority),
negotiated_(config.negotiated),
ordered_(config.ordered),
observer_(nullptr),
controller_(std::move(controller)) {
RTC_DCHECK_RUN_ON(network_thread_);
// Since we constructed on the network thread we can't (yet) check the
// `controller_` pointer since doing so will trigger a thread check.
RTC_UNUSED(network_thread_);
RTC_DCHECK(config.IsValid());
if (connected_to_transport)
network_safety_->SetAlive();
switch (config.open_handshake_role) {
case InternalDataChannelInit::kNone: // pre-negotiated
handshake_state_ = kHandshakeReady;
break;
case InternalDataChannelInit::kOpener:
handshake_state_ = kHandshakeShouldSendOpen;
break;
case InternalDataChannelInit::kAcker:
handshake_state_ = kHandshakeShouldSendAck;
break;
}
}
SctpDataChannel::~SctpDataChannel() {
if (observer_adapter_)
ObserverAdapter::DeleteOnSignalingThread(std::move(observer_adapter_));
}
void SctpDataChannel::RegisterObserver(DataChannelObserver* observer) {
// Note: at this point, we do not know on which thread we're being called
// from since this method bypasses the proxy. On Android in particular,
// registration methods are called from unknown threads.
// Check if we should set up an observer adapter that will make sure that
// callbacks are delivered on the signaling thread rather than directly
// on the network thread.
const auto* current_thread = rtc::Thread::Current();
// TODO(webrtc:11547): Eventually all DataChannelObserver implementations
// should be called on the network thread and IsOkToCallOnTheNetworkThread().
if (!observer->IsOkToCallOnTheNetworkThread()) {
RTC_LOG(LS_WARNING) << "DataChannelObserver - adapter needed";
auto prepare_observer = [&]() {
RTC_DCHECK(observer_adapter_) << "CreateProxy hasn't been called";
observer_adapter_->SetDelegate(observer);
return observer_adapter_.get();
};
// Instantiate the adapter in the right context and then substitute the
// observer pointer the SctpDataChannel will call back on, with the adapter.
if (signaling_thread_ == current_thread) {
observer = prepare_observer();
} else {
observer = signaling_thread_->BlockingCall(std::move(prepare_observer));
}
}
// Now do the observer registration on the network thread. In the common case,
// we'll do this asynchronously via `PostTask()`. For that reason we grab
// a reference to ourselves while the task is in flight. We can't use
// `SafeTask(network_safety_, ...)` for this since we can't assume that we
// have a transport (network_safety_ represents the transport connection).
rtc::scoped_refptr<SctpDataChannel> me(this);
auto register_observer = [me = std::move(me), observer = observer] {
RTC_DCHECK_RUN_ON(me->network_thread_);
me->observer_ = observer;
me->DeliverQueuedReceivedData();
};
if (network_thread_ == current_thread) {
register_observer();
} else {
network_thread_->BlockingCall(std::move(register_observer));
}
}
void SctpDataChannel::UnregisterObserver() {
// Note: As with `RegisterObserver`, the proxy is being bypassed.
const auto* current_thread = rtc::Thread::Current();
// Callers must not be invoking the unregistration from the network thread
// (assuming a multi-threaded environment where we have a dedicated network
// thread). That would indicate non-network related work happening on the
// network thread or that unregistration is being done from within a callback
// (without unwinding the stack, which is a requirement).
// The network thread is not allowed to make blocking calls to the signaling
// thread, so that would blow up if attempted. Since we support an adapter
// for observers that are not safe to call on the network thread, we do
// need to check+free it on the signaling thread.
RTC_DCHECK(current_thread != network_thread_ ||
network_thread_ == signaling_thread_);
auto unregister_observer = [&] {
RTC_DCHECK_RUN_ON(network_thread_);
observer_ = nullptr;
};
if (current_thread == network_thread_) {
unregister_observer();
} else {
network_thread_->BlockingCall(std::move(unregister_observer));
}
auto clear_observer = [&]() {
if (observer_adapter_)
observer_adapter_->SetDelegate(nullptr);
};
if (current_thread != signaling_thread_) {
signaling_thread_->BlockingCall(std::move(clear_observer));
} else {
clear_observer();
}
}
std::string SctpDataChannel::label() const {
return label_;
}
bool SctpDataChannel::reliable() const {
// May be called on any thread.
return !max_retransmits_ && !max_retransmit_time_;
}
bool SctpDataChannel::ordered() const {
return ordered_;
}
uint16_t SctpDataChannel::maxRetransmitTime() const {
return max_retransmit_time_ ? *max_retransmit_time_
: static_cast<uint16_t>(-1);
}
uint16_t SctpDataChannel::maxRetransmits() const {
return max_retransmits_ ? *max_retransmits_ : static_cast<uint16_t>(-1);
}
absl::optional<int> SctpDataChannel::maxPacketLifeTime() const {
return max_retransmit_time_;
}
absl::optional<int> SctpDataChannel::maxRetransmitsOpt() const {
return max_retransmits_;
}
std::string SctpDataChannel::protocol() const {
return protocol_;
}
bool SctpDataChannel::negotiated() const {
return negotiated_;
}
int SctpDataChannel::id() const {
RTC_DCHECK_RUN_ON(network_thread_);
return id_n_.has_value() ? id_n_->stream_id_int() : -1;
}
PriorityValue SctpDataChannel::priority() const {
return priority_.value_or(PriorityValue(Priority::kLow));
}
uint64_t SctpDataChannel::buffered_amount() const {
RTC_DCHECK_RUN_ON(network_thread_);
if (controller_ != nullptr && id_n_.has_value()) {
return controller_->buffered_amount(*id_n_);
}
return 0u;
}
void SctpDataChannel::Close() {
RTC_DCHECK_RUN_ON(network_thread_);
if (state_ == kClosing || state_ == kClosed)
return;
SetState(kClosing);
// Will send queued data before beginning the underlying closing procedure.
UpdateState();
}
SctpDataChannel::DataState SctpDataChannel::state() const {
// Note: The proxy is bypassed for the `state()` accessor. This is to allow
// observer callbacks to query what the new state is from within a state
// update notification without having to do a blocking call to the network
// thread from within a callback. This also makes it so that the returned
// state is guaranteed to be the new state that provoked the state change
// notification, whereby a blocking call to the network thread might end up
// getting put behind other messages on the network thread and eventually
// fetch a different state value (since pending messages might cause the
// state to change in the meantime).
const auto* current_thread = rtc::Thread::Current();
if (current_thread == signaling_thread_ && observer_adapter_ &&
observer_adapter_->IsInsideCallback()) {
return observer_adapter_->cached_state();
}
auto return_state = [&] {
RTC_DCHECK_RUN_ON(network_thread_);
return state_;
};
return current_thread == network_thread_
? return_state()
: network_thread_->BlockingCall(std::move(return_state));
}
RTCError SctpDataChannel::error() const {
const auto* current_thread = rtc::Thread::Current();
if (current_thread == signaling_thread_ && observer_adapter_ &&
observer_adapter_->IsInsideCallback()) {
return observer_adapter_->cached_error();
}
auto return_error = [&] {
RTC_DCHECK_RUN_ON(network_thread_);
return error_;
};
return current_thread == network_thread_
? return_error()
: network_thread_->BlockingCall(std::move(return_error));
}
uint32_t SctpDataChannel::messages_sent() const {
RTC_DCHECK_RUN_ON(network_thread_);
return messages_sent_;
}
uint64_t SctpDataChannel::bytes_sent() const {
RTC_DCHECK_RUN_ON(network_thread_);
return bytes_sent_;
}
uint32_t SctpDataChannel::messages_received() const {
RTC_DCHECK_RUN_ON(network_thread_);
return messages_received_;
}
uint64_t SctpDataChannel::bytes_received() const {
RTC_DCHECK_RUN_ON(network_thread_);
return bytes_received_;
}
bool SctpDataChannel::Send(const DataBuffer& buffer) {
RTC_DCHECK_RUN_ON(network_thread_);
RTCError err = SendImpl(buffer);
if (err.type() == RTCErrorType::INVALID_STATE ||
err.type() == RTCErrorType::RESOURCE_EXHAUSTED) {
return false;
}
// Always return true for SCTP DataChannel per the spec.
return true;
}
// RTC_RUN_ON(network_thread_);
RTCError SctpDataChannel::SendImpl(DataBuffer buffer) {
// The caller increases the cached `bufferedAmount` even if there are errors.
expected_buffer_amount_ += buffer.size();
if (state_ != kOpen) {
error_ = RTCError(RTCErrorType::INVALID_STATE);
return error_;
}
return SendDataMessage(buffer, true);
}
void SctpDataChannel::SendAsync(
DataBuffer buffer,
absl::AnyInvocable<void(RTCError) &&> on_complete) {
// Note: at this point, we do not know on which thread we're being called
// since this method bypasses the proxy. On Android the thread might be VM
// owned, on other platforms it might be the signaling thread, or in Chrome
// it can be the JS thread. We also don't know if it's consistently the same
// thread. So we always post to the network thread (even if the current thread
// might be the network thread - in theory a call could even come from within
// the `on_complete` callback).
network_thread_->PostTask(SafeTask(
network_safety_, [this, buffer = std::move(buffer),
on_complete = std::move(on_complete)]() mutable {
RTC_DCHECK_RUN_ON(network_thread_);
RTCError err = SendImpl(std::move(buffer));
if (on_complete)
std::move(on_complete)(err);
}));
}
void SctpDataChannel::SetSctpSid_n(StreamId sid) {
RTC_DCHECK_RUN_ON(network_thread_);
RTC_DCHECK(!id_n_.has_value());
RTC_DCHECK_NE(handshake_state_, kHandshakeWaitingForAck);
RTC_DCHECK_EQ(state_, kConnecting);
id_n_ = sid;
}
void SctpDataChannel::OnClosingProcedureStartedRemotely() {
RTC_DCHECK_RUN_ON(network_thread_);
if (state_ != kClosing && state_ != kClosed) {
// Don't bother sending queued data since the side that initiated the
// closure wouldn't receive it anyway. See crbug.com/559394 for a lengthy
// discussion about this.
// Note that this is handled by the SctpTransport, when an incoming stream
// reset notification comes in, the outgoing stream is closed, which
// discards data.
// Just need to change state to kClosing, SctpTransport will handle the
// rest of the closing procedure and OnClosingProcedureComplete will be
// called later.
started_closing_procedure_ = true;
SetState(kClosing);
}
}
void SctpDataChannel::OnClosingProcedureComplete() {
RTC_DCHECK_RUN_ON(network_thread_);
// If the closing procedure is complete, we should have finished sending
// all pending data and transitioned to kClosing already.
RTC_DCHECK_EQ(state_, kClosing);
if (controller_ && id_n_.has_value()) {
RTC_DCHECK_EQ(controller_->buffered_amount(*id_n_), 0);
}
SetState(kClosed);
}
void SctpDataChannel::OnTransportChannelCreated() {
RTC_DCHECK_RUN_ON(network_thread_);
network_safety_->SetAlive();
}
void SctpDataChannel::OnTransportChannelClosed(RTCError error) {
RTC_DCHECK_RUN_ON(network_thread_);
// The SctpTransport is unusable, which could come from multiple reasons:
// - the SCTP m= section was rejected
// - the DTLS transport is closed
// - the SCTP transport is closed
CloseAbruptlyWithError(std::move(error));
}
void SctpDataChannel::OnBufferedAmountLow() {
RTC_DCHECK_RUN_ON(network_thread_);
MaybeSendOnBufferedAmountChanged();
if (state_ == DataChannelInterface::kClosing && !started_closing_procedure_ &&
id_n_.has_value() && buffered_amount() == 0) {
started_closing_procedure_ = true;
controller_->RemoveSctpDataStream(*id_n_);
}
}
DataChannelStats SctpDataChannel::GetStats() const {
RTC_DCHECK_RUN_ON(network_thread_);
DataChannelStats stats{internal_id_, id(), label(),
protocol(), state(), messages_sent(),
messages_received(), bytes_sent(), bytes_received()};
return stats;
}
void SctpDataChannel::OnDataReceived(DataMessageType type,
const rtc::CopyOnWriteBuffer& payload) {
RTC_DCHECK_RUN_ON(network_thread_);
RTC_DCHECK(id_n_.has_value());
if (type == DataMessageType::kControl) {
if (handshake_state_ != kHandshakeWaitingForAck) {
// Ignore it if we are not expecting an ACK message.
RTC_LOG(LS_WARNING)
<< "DataChannel received unexpected CONTROL message, sid = "
<< id_n_->stream_id_int();
return;
}
if (ParseDataChannelOpenAckMessage(payload)) {
// We can send unordered as soon as we receive the ACK message.
handshake_state_ = kHandshakeReady;
RTC_LOG(LS_INFO) << "DataChannel received OPEN_ACK message, sid = "
<< id_n_->stream_id_int();
} else {
RTC_LOG(LS_WARNING)
<< "DataChannel failed to parse OPEN_ACK message, sid = "
<< id_n_->stream_id_int();
}
return;
}
RTC_DCHECK(type == DataMessageType::kBinary ||
type == DataMessageType::kText);
RTC_DLOG(LS_VERBOSE) << "DataChannel received DATA message, sid = "
<< id_n_->stream_id_int();
// We can send unordered as soon as we receive any DATA message since the
// remote side must have received the OPEN (and old clients do not send
// OPEN_ACK).
if (handshake_state_ == kHandshakeWaitingForAck) {
handshake_state_ = kHandshakeReady;
}
bool binary = (type == DataMessageType::kBinary);
auto buffer = std::make_unique<DataBuffer>(payload, binary);
if (state_ == kOpen && observer_) {
++messages_received_;
bytes_received_ += buffer->size();
observer_->OnMessage(*buffer.get());
} else {
if (queued_received_data_.byte_count() + payload.size() >
kMaxQueuedReceivedDataBytes) {
RTC_LOG(LS_ERROR) << "Queued received data exceeds the max buffer size.";
queued_received_data_.Clear();
CloseAbruptlyWithError(
RTCError(RTCErrorType::RESOURCE_EXHAUSTED,
"Queued received data exceeds the max buffer size."));
return;
}
queued_received_data_.PushBack(std::move(buffer));
}
}
void SctpDataChannel::OnTransportReady() {
RTC_DCHECK_RUN_ON(network_thread_);
RTC_DCHECK(connected_to_transport());
RTC_DCHECK(id_n_.has_value());
UpdateState();
}
void SctpDataChannel::CloseAbruptlyWithError(RTCError error) {
RTC_DCHECK_RUN_ON(network_thread_);
if (state_ == kClosed) {
return;
}
network_safety_->SetNotAlive();
// Still go to "kClosing" before "kClosed", since observers may be expecting
// that.
SetState(kClosing);
error_ = std::move(error);
SetState(kClosed);
}
void SctpDataChannel::CloseAbruptlyWithDataChannelFailure(
const std::string& message) {
RTC_DCHECK_RUN_ON(network_thread_);
RTCError error(RTCErrorType::OPERATION_ERROR_WITH_DATA, message);
error.set_error_detail(RTCErrorDetailType::DATA_CHANNEL_FAILURE);
CloseAbruptlyWithError(std::move(error));
}
// RTC_RUN_ON(network_thread_).
void SctpDataChannel::UpdateState() {
// UpdateState determines what to do from a few state variables. Include
// all conditions required for each state transition here for
// clarity. OnTransportReady(true) will send any queued data and then invoke
// UpdateState().
switch (state_) {
case kConnecting: {
if (connected_to_transport() && controller_) {
if (handshake_state_ == kHandshakeShouldSendOpen) {
rtc::CopyOnWriteBuffer payload;
WriteDataChannelOpenMessage(label_, protocol_, priority_, ordered_,
max_retransmits_, max_retransmit_time_,
&payload);
SendControlMessage(payload);
} else if (handshake_state_ == kHandshakeShouldSendAck) {
rtc::CopyOnWriteBuffer payload;
WriteDataChannelOpenAckMessage(&payload);
SendControlMessage(payload);
}
if (handshake_state_ == kHandshakeReady ||
handshake_state_ == kHandshakeWaitingForAck) {
SetState(kOpen);
// If we have received buffers before the channel got writable.
// Deliver them now.
DeliverQueuedReceivedData();
}
} else {
RTC_DCHECK(!id_n_.has_value());
}
break;
}
case kOpen: {
break;
}
case kClosing: {
if (connected_to_transport() && controller_ && id_n_.has_value()) {
// Wait for all queued data to be sent before beginning the closing
// procedure.
if (controller_->buffered_amount(*id_n_) == 0) {
// For SCTP data channels, we need to wait for the closing procedure
// to complete; after calling RemoveSctpDataStream,
// OnClosingProcedureComplete will end up called asynchronously
// afterwards.
if (!started_closing_procedure_ && id_n_.has_value()) {
started_closing_procedure_ = true;
controller_->RemoveSctpDataStream(*id_n_);
}
}
} else {
// When we're not connected to a transport, we'll transition
// directly to the `kClosed` state from here.
SetState(kClosed);
}
break;
}
case kClosed:
break;
}
}
// RTC_RUN_ON(network_thread_).
void SctpDataChannel::SetState(DataState state) {
if (state_ == state) {
return;
}
state_ = state;
if (observer_) {
observer_->OnStateChange();
}
if (controller_)
controller_->OnChannelStateChanged(this, state_);
}
// RTC_RUN_ON(network_thread_).
void SctpDataChannel::DeliverQueuedReceivedData() {
if (!observer_ || state_ != kOpen) {
return;
}
while (!queued_received_data_.Empty()) {
std::unique_ptr<DataBuffer> buffer = queued_received_data_.PopFront();
++messages_received_;
bytes_received_ += buffer->size();
observer_->OnMessage(*buffer);
}
}
// RTC_RUN_ON(network_thread_)
void SctpDataChannel::MaybeSendOnBufferedAmountChanged() {
// The `buffered_amount` in the signaling thread (RTCDataChannel in Blink)
// has a cached variant of the SCTP socket's buffered_amount, which it
// increases for every data sent and decreased when `OnBufferedAmountChange`
// is sent.
//
// To ensure it's consistent, this object maintains its own view of that value
// and if it changes with a reasonable amount (10kb, or down to zero), send
// the `OnBufferedAmountChange` to update the caller's cached variable.
if (!controller_ || !id_n_.has_value() || !observer_) {
return;
}
// This becomes the resolution of how often the bufferedAmount is updated on
// the signaling thread and exists to avoid doing cross-thread communication
// too often. On benchmarks, Chrome handle around 300Mbps, which with this
// size results in a rate of ~400 updates per second - a reasonable number.
static constexpr int64_t kMinBufferedAmountDiffToTriggerCallback = 100 * 1024;
size_t actual_buffer_amount = controller_->buffered_amount(*id_n_);
if (actual_buffer_amount > expected_buffer_amount_) {
RTC_DLOG(LS_ERROR) << "Actual buffer_amount larger than expected";
return;
}
// Fire OnBufferedAmountChange to decrease the cached view if it represents a
// big enough change (to reduce the frequency of cross-thread communication),
// or if it reaches zero.
if ((actual_buffer_amount == 0 && expected_buffer_amount_ != 0) ||
(expected_buffer_amount_ - actual_buffer_amount >
kMinBufferedAmountDiffToTriggerCallback)) {
uint64_t diff = expected_buffer_amount_ - actual_buffer_amount;
expected_buffer_amount_ = actual_buffer_amount;
observer_->OnBufferedAmountChange(diff);
}
// The threshold is always updated to ensure it's lower than what it's now.
// This ensures that this function will be called again, until the channel is
// completely drained.
controller_->SetBufferedAmountLowThreshold(
*id_n_,
actual_buffer_amount > kMinBufferedAmountDiffToTriggerCallback
? actual_buffer_amount - kMinBufferedAmountDiffToTriggerCallback
: 0);
}
// RTC_RUN_ON(network_thread_).
RTCError SctpDataChannel::SendDataMessage(const DataBuffer& buffer,
bool queue_if_blocked) {
SendDataParams send_params;
if (!controller_ || !id_n_.has_value()) {
error_ = RTCError(RTCErrorType::INVALID_STATE);
return error_;
}
send_params.ordered = ordered_;
// Send as ordered if it is still going through OPEN/ACK signaling.
if (handshake_state_ != kHandshakeReady && !ordered_) {
send_params.ordered = true;
RTC_DLOG(LS_VERBOSE)
<< "Sending data as ordered for unordered DataChannel "
"because the OPEN_ACK message has not been received.";
}
send_params.max_rtx_count = max_retransmits_;
send_params.max_rtx_ms = max_retransmit_time_;
send_params.type =
buffer.binary ? DataMessageType::kBinary : DataMessageType::kText;
error_ = controller_->SendData(*id_n_, send_params, buffer.data);
MaybeSendOnBufferedAmountChanged();
if (error_.ok()) {
++messages_sent_;
bytes_sent_ += buffer.size();
return error_;
}
// Close the channel if the error is not SDR_BLOCK, or if queuing the
// message failed.
RTC_LOG(LS_ERROR) << "Closing the DataChannel due to a failure to send data, "
"send_result = "
<< ToString(error_.type()) << ":" << error_.message();
CloseAbruptlyWithError(
RTCError(RTCErrorType::NETWORK_ERROR, "Failure to send data"));
return error_;
}
// RTC_RUN_ON(network_thread_).
bool SctpDataChannel::SendControlMessage(const rtc::CopyOnWriteBuffer& buffer) {
RTC_DCHECK(connected_to_transport());
RTC_DCHECK(id_n_.has_value());
RTC_DCHECK(controller_);
bool is_open_message = handshake_state_ == kHandshakeShouldSendOpen;
RTC_DCHECK(!is_open_message || !negotiated_);
SendDataParams send_params;
// Send data as ordered before we receive any message from the remote peer to
// make sure the remote peer will not receive any data before it receives the
// OPEN message.
send_params.ordered = ordered_ || is_open_message;
send_params.type = DataMessageType::kControl;
RTCError err = controller_->SendData(*id_n_, send_params, buffer);
if (err.ok()) {
RTC_DLOG(LS_VERBOSE) << "Sent CONTROL message on channel "
<< id_n_->stream_id_int();
if (handshake_state_ == kHandshakeShouldSendAck) {
handshake_state_ = kHandshakeReady;
} else if (handshake_state_ == kHandshakeShouldSendOpen) {
handshake_state_ = kHandshakeWaitingForAck;
}
} else {
RTC_LOG(LS_ERROR) << "Closing the DataChannel due to a failure to send"
" the CONTROL message, send_result = "
<< ToString(err.type());
err.set_message("Failed to send a CONTROL message");
CloseAbruptlyWithError(err);
}
return err.ok();
}
// static
void SctpDataChannel::ResetInternalIdAllocatorForTesting(int new_value) {
g_unique_id = new_value;
}
} // namespace webrtc