添加 github.com/pion/dtls 代码

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

@@ -0,0 +1,70 @@
+package extension
+
+import (
+	"encoding/binary"
+
+	"github.com/pion/dtls/v2/pkg/crypto/hash"
+	"github.com/pion/dtls/v2/pkg/crypto/signature"
+	"github.com/pion/dtls/v2/pkg/crypto/signaturehash"
+)
+
+const (
+	supportedSignatureAlgorithmsHeaderSize = 6
+)
+
+// SupportedSignatureAlgorithms allows a Client/Server to
+// negotiate what SignatureHash Algorithms they both support
+//
+// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
+type SupportedSignatureAlgorithms struct {
+	SignatureHashAlgorithms []signaturehash.Algorithm
+}
+
+// TypeValue returns the extension TypeValue
+func (s SupportedSignatureAlgorithms) TypeValue() TypeValue {
+	return SupportedSignatureAlgorithmsTypeValue
+}
+
+// Marshal encodes the extension
+func (s *SupportedSignatureAlgorithms) Marshal() ([]byte, error) {
+	out := make([]byte, supportedSignatureAlgorithmsHeaderSize)
+
+	binary.BigEndian.PutUint16(out, uint16(s.TypeValue()))
+	binary.BigEndian.PutUint16(out[2:], uint16(2+(len(s.SignatureHashAlgorithms)*2)))
+	binary.BigEndian.PutUint16(out[4:], uint16(len(s.SignatureHashAlgorithms)*2))
+	for _, v := range s.SignatureHashAlgorithms {
+		out = append(out, []byte{0x00, 0x00}...)
+		out[len(out)-2] = byte(v.Hash)
+		out[len(out)-1] = byte(v.Signature)
+	}
+
+	return out, nil
+}
+
+// Unmarshal populates the extension from encoded data
+func (s *SupportedSignatureAlgorithms) Unmarshal(data []byte) error {
+	if len(data) <= supportedSignatureAlgorithmsHeaderSize {
+		return errBufferTooSmall
+	} else if TypeValue(binary.BigEndian.Uint16(data)) != s.TypeValue() {
+		return errInvalidExtensionType
+	}
+
+	algorithmCount := int(binary.BigEndian.Uint16(data[4:]) / 2)
+	if supportedSignatureAlgorithmsHeaderSize+(algorithmCount*2) > len(data) {
+		return errLengthMismatch
+	}
+	for i := 0; i < algorithmCount; i++ {
+		supportedHashAlgorithm := hash.Algorithm(data[supportedSignatureAlgorithmsHeaderSize+(i*2)])
+		supportedSignatureAlgorithm := signature.Algorithm(data[supportedSignatureAlgorithmsHeaderSize+(i*2)+1])
+		if _, ok := hash.Algorithms()[supportedHashAlgorithm]; ok {
+			if _, ok := signature.Algorithms()[supportedSignatureAlgorithm]; ok {
+				s.SignatureHashAlgorithms = append(s.SignatureHashAlgorithms, signaturehash.Algorithm{
+					Hash:      supportedHashAlgorithm,
+					Signature: supportedSignatureAlgorithm,
+				})
+			}
+		}
+	}
+
+	return nil
+}