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121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
/*
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* Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef NET_DCSCTP_PACKET_SCTP_PACKET_H_
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#define NET_DCSCTP_PACKET_SCTP_PACKET_H_
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#include <stddef.h>
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#include <cstdint>
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#include <functional>
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#include <memory>
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#include <utility>
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#include <vector>
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#include "api/array_view.h"
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#include "net/dcsctp/common/internal_types.h"
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#include "net/dcsctp/packet/chunk/chunk.h"
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#include "net/dcsctp/public/dcsctp_options.h"
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namespace dcsctp {
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// The "Common Header", which every SCTP packet starts with, and is described in
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// https://tools.ietf.org/html/rfc4960#section-3.1.
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struct CommonHeader {
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uint16_t source_port;
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uint16_t destination_port;
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VerificationTag verification_tag;
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uint32_t checksum;
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};
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// Represents an immutable (received or to-be-sent) SCTP packet.
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class SctpPacket {
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public:
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static constexpr size_t kHeaderSize = 12;
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struct ChunkDescriptor {
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ChunkDescriptor(uint8_t type,
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uint8_t flags,
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rtc::ArrayView<const uint8_t> data)
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: type(type), flags(flags), data(data) {}
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uint8_t type;
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uint8_t flags;
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rtc::ArrayView<const uint8_t> data;
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};
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SctpPacket(SctpPacket&& other) = default;
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SctpPacket& operator=(SctpPacket&& other) = default;
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SctpPacket(const SctpPacket&) = delete;
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SctpPacket& operator=(const SctpPacket&) = delete;
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// Used for building SctpPacket, as those are immutable.
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class Builder {
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public:
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Builder(VerificationTag verification_tag, const DcSctpOptions& options);
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Builder(Builder&& other) = default;
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Builder& operator=(Builder&& other) = default;
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// Adds a chunk to the to-be-built SCTP packet.
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Builder& Add(const Chunk& chunk);
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// The number of bytes remaining in the packet for chunk storage until the
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// packet reaches its maximum size.
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size_t bytes_remaining() const;
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// Indicates if any packets have been added to the builder.
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bool empty() const { return out_.empty(); }
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// Returns the payload of the build SCTP packet. The Builder will be cleared
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// after having called this function, and can be used to build a new packet.
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std::vector<uint8_t> Build();
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private:
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VerificationTag verification_tag_;
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uint16_t source_port_;
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uint16_t dest_port_;
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// The maximum packet size is always even divisible by four, as chunks are
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// always padded to a size even divisible by four.
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size_t max_packet_size_;
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std::vector<uint8_t> out_;
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};
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// Parses `data` as an SCTP packet and returns it if it validates.
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static absl::optional<SctpPacket> Parse(
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rtc::ArrayView<const uint8_t> data,
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bool disable_checksum_verification = false);
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// Returns the SCTP common header.
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const CommonHeader& common_header() const { return common_header_; }
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// Returns the chunks (types and offsets) within the packet.
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rtc::ArrayView<const ChunkDescriptor> descriptors() const {
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return descriptors_;
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}
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private:
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SctpPacket(const CommonHeader& common_header,
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std::vector<uint8_t> data,
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std::vector<ChunkDescriptor> descriptors)
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: common_header_(common_header),
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data_(std::move(data)),
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descriptors_(std::move(descriptors)) {}
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CommonHeader common_header_;
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// As the `descriptors_` refer to offset within data, and since SctpPacket is
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// movable, `data` needs to be pointer stable, which it is according to
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// http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#2321
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std::vector<uint8_t> data_;
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// The chunks and their offsets within `data_ `.
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std::vector<ChunkDescriptor> descriptors_;
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};
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} // namespace dcsctp
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#endif // NET_DCSCTP_PACKET_SCTP_PACKET_H_
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