tor-browser

data_channel_transport_interface.h (5557B)

---

/* Copyright 2019 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.
*/

// This is an experimental interface and is subject to change without notice.

#ifndef API_TRANSPORT_DATA_CHANNEL_TRANSPORT_INTERFACE_H_
#define API_TRANSPORT_DATA_CHANNEL_TRANSPORT_INTERFACE_H_

#include <cstddef>
#include <optional>

#include "api/priority.h"
#include "api/rtc_error.h"
#include "rtc_base/copy_on_write_buffer.h"

namespace webrtc {

// Supported types of application data messages.
enum class DataMessageType {
 // Application data buffer with the binary bit unset.
 kText,

 // Application data buffer with the binary bit set.
 kBinary,

 // Transport-agnostic control messages, such as open or open-ack messages.
 kControl,
};

// Parameters for sending data.  The parameters may change from message to
// message, even within a single channel.  For example, control messages may be
// sent reliably and in-order, even if the data channel is configured for
// unreliable delivery.
struct SendDataParams {
 DataMessageType type = DataMessageType::kText;

 // Whether to deliver the message in order with respect to other ordered
 // messages with the same channel_id.
 bool ordered = false;

 // If set, the maximum number of times this message may be
 // retransmitted by the transport before it is dropped.
 // Setting this value to zero disables retransmission.
 // Valid values are in the range [0-UINT16_MAX].
 // `max_rtx_count` and `max_rtx_ms` may not be set simultaneously.
 std::optional<int> max_rtx_count;

 // If set, the maximum number of milliseconds for which the transport
 // may retransmit this message before it is dropped.
 // Setting this value to zero disables retransmission.
 // Valid values are in the range [0-UINT16_MAX].
 // `max_rtx_count` and `max_rtx_ms` may not be set simultaneously.
 std::optional<int> max_rtx_ms;
};

// Sink for callbacks related to a data channel.
class DataChannelSink {
public:
 virtual ~DataChannelSink() = default;

 // Callback issued when data is received by the transport.
 virtual void OnDataReceived(int channel_id,
                             DataMessageType type,
                             const CopyOnWriteBuffer& buffer) = 0;

 // Callback issued when a remote data channel begins the closing procedure.
 // Messages sent after the closing procedure begins will not be transmitted.
 virtual void OnChannelClosing(int channel_id) = 0;

 // Callback issued when a (remote or local) data channel completes the closing
 // procedure.  Closing channels become closed after all pending data has been
 // transmitted.
 virtual void OnChannelClosed(int channel_id) = 0;

 // Callback issued when the data channel becomes ready to send.
 // This callback will be issued immediately when the data channel sink is
 // registered if the transport is ready at that time.  This callback may be
 // invoked again following send errors (eg. due to the transport being
 // temporarily blocked or unavailable).
 virtual void OnReadyToSend() = 0;

 // Callback issued when the data channel becomes unusable (closed).
 // TODO(https://crbug.com/webrtc/10360): Make pure virtual when all
 // consumers updated.
 virtual void OnTransportClosed(RTCError /* error */) {}

 // The data channel's buffered_amount has fallen to or below the threshold
 // set when calling `SetBufferedAmountLowThreshold`
 virtual void OnBufferedAmountLow(int channel_id) = 0;
};

// Transport for data channels.
class DataChannelTransportInterface {
public:
 virtual ~DataChannelTransportInterface() = default;

 // Opens a data `channel_id` for sending.  May return an error if the
 // specified `channel_id` is unusable.  Must be called before `SendData`.
 virtual RTCError OpenChannel(int channel_id, PriorityValue priority) = 0;

 // Sends a data buffer to the remote endpoint using the given send parameters.
 // `buffer` may not be larger than 256 KiB. Returns an error if the send
 // fails.
 virtual RTCError SendData(int channel_id,
                           const SendDataParams& params,
                           const CopyOnWriteBuffer& buffer) = 0;

 // Closes `channel_id` gracefully.  Returns an error if `channel_id` is not
 // open.  Data sent after the closing procedure begins will not be
 // transmitted. The channel becomes closed after pending data is transmitted.
 virtual RTCError CloseChannel(int channel_id) = 0;

 // Sets a sink for data messages and channel state callbacks. Before media
 // transport is destroyed, the sink must be unregistered by setting it to
 // nullptr.
 virtual void SetDataSink(DataChannelSink* sink) = 0;

 // Returns whether this data channel transport is ready to send.
 // Note: the default implementation always returns false (as it assumes no one
 // has implemented the interface).  This default implementation is temporary.
 virtual bool IsReadyToSend() const = 0;

 virtual size_t buffered_amount(int channel_id) const = 0;
 virtual size_t buffered_amount_low_threshold(int channel_id) const = 0;
 virtual void SetBufferedAmountLowThreshold(int channel_id, size_t bytes) = 0;
};

}  // namespace webrtc

#endif  // API_TRANSPORT_DATA_CHANNEL_TRANSPORT_INTERFACE_H_