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* Copyright (c) 2021 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 <cstdint>
#include <utility>
#include <vector>
#include "net/dcsctp/common/internal_types.h"
#include "net/dcsctp/public/types.h"
namespace dcsctp {
// Represents data that is either received and extracted from a DATA/I-DATA
// chunk, or data that is supposed to be sent, and wrapped in a DATA/I-DATA
// chunk (depending on peer capabilities).
// The data wrapped in this structure is actually the same as the DATA/I-DATA
// chunk (actually the union of them), but to avoid having all components be
// aware of the implementation details of the different chunks, this abstraction
// is used instead. A notable difference is also that it doesn't carry a
// Transmission Sequence Number (TSN), as that is not known when a chunk is
// created (assigned late, just when sending), and that the TSNs in DATA/I-DATA
// are wrapped numbers, and within the library, unwrapped sequence numbers are
// preferably used.
struct Data {
// Indicates if a chunk is the first in a fragmented message and maps to the
// "beginning" flag in DATA/I-DATA chunk.
using IsBeginning = StrongAlias<class IsBeginningTag, bool>;
// Indicates if a chunk is the last in a fragmented message and maps to the
// "end" flag in DATA/I-DATA chunk.
using IsEnd = StrongAlias<class IsEndTag, bool>;
Data(StreamID stream_id,
SSN ssn,
MID message_id,
FSN fsn,
PPID ppid,
std::vector<uint8_t> payload,
IsBeginning is_beginning,
IsEnd is_end,
IsUnordered is_unordered)
: stream_id(stream_id),
is_unordered(is_unordered) {}
// Move-only, to avoid accidental copies.
Data(Data&& other) = default;
Data& operator=(Data&& other) = default;
// Creates a copy of this `Data` object.
Data Clone() const {
return Data(stream_id, ssn, message_id, fsn, ppid, payload, is_beginning,
is_end, is_unordered);
// The size of this data, which translates to the size of its payload.
size_t size() const { return payload.size(); }
// Stream Identifier.
StreamID stream_id;
// Stream Sequence Number (SSN), per stream, for ordered chunks. Defined by
// RFC4960 and used only in DATA chunks (not I-DATA).
SSN ssn;
// Message Identifier (MID) per stream and ordered/unordered. Defined by
// RFC8260, and used together with options.is_unordered and stream_id to
// uniquely identify a message. Used only in I-DATA chunks (not DATA).
MID message_id;
// Fragment Sequence Number (FSN) per stream and ordered/unordered, as above.
FSN fsn;
// Payload Protocol Identifier (PPID).
PPID ppid;
// The actual data payload.
std::vector<uint8_t> payload;
// If this data represents the first, last or a middle chunk.
IsBeginning is_beginning;
IsEnd is_end;
// If this data is sent/received unordered.
IsUnordered is_unordered;
} // namespace dcsctp