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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package extension
import (
"encoding/binary"
"github.com/pion/dtls/v3/pkg/crypto/elliptic"
)
const (
supportedPointFormatsSize = 5
)
// SupportedPointFormats allows a Client/Server to negotiate
// the EllipticCurvePointFormats
//
// https://tools.ietf.org/html/rfc4492#section-5.1.2
type SupportedPointFormats struct {
PointFormats []elliptic.CurvePointFormat
}
// TypeValue returns the extension TypeValue.
func (s SupportedPointFormats) TypeValue() TypeValue {
return SupportedPointFormatsTypeValue
}
// Marshal encodes the extension.
func (s *SupportedPointFormats) Marshal() ([]byte, error) {
out := make([]byte, supportedPointFormatsSize)
binary.BigEndian.PutUint16(out, uint16(s.TypeValue()))
binary.BigEndian.PutUint16(out[2:], uint16(1+(len(s.PointFormats)))) //nolint:gosec // G115
out[4] = byte(len(s.PointFormats))
for _, v := range s.PointFormats {
out = append(out, byte(v)) //nolint:makezero // todo: fix
}
return out, nil
}
// Unmarshal populates the extension from encoded data.
func (s *SupportedPointFormats) Unmarshal(data []byte) error {
if len(data) <= supportedPointFormatsSize {
return errBufferTooSmall
}
if TypeValue(binary.BigEndian.Uint16(data)) != s.TypeValue() {
return errInvalidExtensionType
}
pointFormatCount := int(data[4])
if supportedPointFormatsSize+pointFormatCount > len(data) {
return errLengthMismatch
}
for i := 0; i < pointFormatCount; i++ {
p := elliptic.CurvePointFormat(data[supportedPointFormatsSize+i])
switch p {
case elliptic.CurvePointFormatUncompressed:
s.PointFormats = append(s.PointFormats, p)
default:
}
}
return nil
}
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