63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
package extension
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import (
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"encoding/binary"
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"github.com/pion/dtls/v2/pkg/crypto/elliptic"
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)
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const (
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supportedPointFormatsSize = 5
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)
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// SupportedPointFormats allows a Client/Server to negotiate
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// the EllipticCurvePointFormats
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//
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// https://tools.ietf.org/html/rfc4492#section-5.1.2
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type SupportedPointFormats struct {
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PointFormats []elliptic.CurvePointFormat
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}
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// TypeValue returns the extension TypeValue
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func (s SupportedPointFormats) TypeValue() TypeValue {
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return SupportedPointFormatsTypeValue
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}
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// Marshal encodes the extension
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func (s *SupportedPointFormats) Marshal() ([]byte, error) {
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out := make([]byte, supportedPointFormatsSize)
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binary.BigEndian.PutUint16(out, uint16(s.TypeValue()))
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binary.BigEndian.PutUint16(out[2:], uint16(1+(len(s.PointFormats))))
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out[4] = byte(len(s.PointFormats))
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for _, v := range s.PointFormats {
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out = append(out, byte(v))
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}
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return out, nil
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}
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// Unmarshal populates the extension from encoded data
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func (s *SupportedPointFormats) Unmarshal(data []byte) error {
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if len(data) <= supportedPointFormatsSize {
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return errBufferTooSmall
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} else if TypeValue(binary.BigEndian.Uint16(data)) != s.TypeValue() {
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return errInvalidExtensionType
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}
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pointFormatCount := int(binary.BigEndian.Uint16(data[4:]))
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if supportedGroupsHeaderSize+(pointFormatCount) > len(data) {
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return errLengthMismatch
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}
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for i := 0; i < pointFormatCount; i++ {
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p := elliptic.CurvePointFormat(data[supportedPointFormatsSize+i])
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switch p {
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case elliptic.CurvePointFormatUncompressed:
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s.PointFormats = append(s.PointFormats, p)
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default:
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}
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}
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return nil
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}
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