添加 github.com/pion/dtls 代码

dtls-2.0.9/pkg/protocol/extension/supported_point_formats.go

@@ -0,0 +1,62 @@
+package extension
+
+import (
+	"encoding/binary"
+
+	"github.com/pion/dtls/v2/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))))
+	out[4] = byte(len(s.PointFormats))
+
+	for _, v := range s.PointFormats {
+		out = append(out, byte(v))
+	}
+	return out, nil
+}
+
+// Unmarshal populates the extension from encoded data
+func (s *SupportedPointFormats) Unmarshal(data []byte) error {
+	if len(data) <= supportedPointFormatsSize {
+		return errBufferTooSmall
+	} else if TypeValue(binary.BigEndian.Uint16(data)) != s.TypeValue() {
+		return errInvalidExtensionType
+	}
+
+	pointFormatCount := int(binary.BigEndian.Uint16(data[4:]))
+	if supportedGroupsHeaderSize+(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
+}