51 lines
1.4 KiB
Go
51 lines
1.4 KiB
Go
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package handshake
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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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)
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// HeaderLength msg_len for Handshake messages assumes an extra
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// 12 bytes for sequence, fragment and version information vs TLS
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const HeaderLength = 12
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// Header is the static first 12 bytes of each RecordLayer
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// of type Handshake. These fields allow us to support message loss, reordering, and
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// message fragmentation,
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//
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// https://tools.ietf.org/html/rfc6347#section-4.2.2
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type Header struct {
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Type Type
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Length uint32 // uint24 in spec
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MessageSequence uint16
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FragmentOffset uint32 // uint24 in spec
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FragmentLength uint32 // uint24 in spec
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}
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// Marshal encodes the Header
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func (h *Header) Marshal() ([]byte, error) {
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out := make([]byte, HeaderLength)
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out[0] = byte(h.Type)
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util.PutBigEndianUint24(out[1:], h.Length)
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binary.BigEndian.PutUint16(out[4:], h.MessageSequence)
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util.PutBigEndianUint24(out[6:], h.FragmentOffset)
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util.PutBigEndianUint24(out[9:], h.FragmentLength)
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return out, nil
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}
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// Unmarshal populates the header from encoded data
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func (h *Header) Unmarshal(data []byte) error {
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if len(data) < HeaderLength {
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return errBufferTooSmall
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}
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h.Type = Type(data[0])
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h.Length = util.BigEndianUint24(data[1:])
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h.MessageSequence = binary.BigEndian.Uint16(data[4:])
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h.FragmentOffset = util.BigEndianUint24(data[6:])
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h.FragmentLength = util.BigEndianUint24(data[9:])
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return nil
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}
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