mirror of https://github.com/bjdgyc/anylink.git
62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
package recordlayer
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import (
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"encoding/binary"
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"github.com/pion/dtls/v2/internal/util"
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"github.com/pion/dtls/v2/pkg/protocol"
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)
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// Header implements a TLS RecordLayer header
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type Header struct {
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ContentType protocol.ContentType
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ContentLen uint16
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Version protocol.Version
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Epoch uint16
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SequenceNumber uint64 // uint48 in spec
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}
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// RecordLayer enums
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const (
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HeaderSize = 13
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MaxSequenceNumber = 0x0000FFFFFFFFFFFF
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)
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// Marshal encodes a TLS RecordLayer Header to binary
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func (h *Header) Marshal() ([]byte, error) {
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if h.SequenceNumber > MaxSequenceNumber {
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return nil, errSequenceNumberOverflow
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}
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out := make([]byte, HeaderSize)
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out[0] = byte(h.ContentType)
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out[1] = h.Version.Major
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out[2] = h.Version.Minor
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binary.BigEndian.PutUint16(out[3:], h.Epoch)
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util.PutBigEndianUint48(out[5:], h.SequenceNumber)
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binary.BigEndian.PutUint16(out[HeaderSize-2:], h.ContentLen)
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return out, nil
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}
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// Unmarshal populates a TLS RecordLayer Header from binary
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func (h *Header) Unmarshal(data []byte) error {
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if len(data) < HeaderSize {
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return errBufferTooSmall
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}
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h.ContentType = protocol.ContentType(data[0])
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h.Version.Major = data[1]
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h.Version.Minor = data[2]
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h.Epoch = binary.BigEndian.Uint16(data[3:])
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// SequenceNumber is stored as uint48, make into uint64
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seqCopy := make([]byte, 8)
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copy(seqCopy[2:], data[5:11])
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h.SequenceNumber = binary.BigEndian.Uint64(seqCopy)
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if !h.Version.Equal(protocol.Version1_0) && !h.Version.Equal(protocol.Version1_2) {
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return errUnsupportedProtocolVersion
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}
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return nil
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}
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