添加 github.com/pion/dtls 代码

dtls-2.0.9/pkg/protocol/handshake/message_server_key_exchange.go

@@ -0,0 +1,119 @@
+package handshake
+
+import (
+	"encoding/binary"
+
+	"github.com/pion/dtls/v2/pkg/crypto/elliptic"
+	"github.com/pion/dtls/v2/pkg/crypto/hash"
+	"github.com/pion/dtls/v2/pkg/crypto/signature"
+)
+
+// MessageServerKeyExchange supports ECDH and PSK
+type MessageServerKeyExchange struct {
+	IdentityHint []byte
+
+	EllipticCurveType  elliptic.CurveType
+	NamedCurve         elliptic.Curve
+	PublicKey          []byte
+	HashAlgorithm      hash.Algorithm
+	SignatureAlgorithm signature.Algorithm
+	Signature          []byte
+}
+
+// Type returns the Handshake Type
+func (m MessageServerKeyExchange) Type() Type {
+	return TypeServerKeyExchange
+}
+
+// Marshal encodes the Handshake
+func (m *MessageServerKeyExchange) Marshal() ([]byte, error) {
+	if m.IdentityHint != nil {
+		out := append([]byte{0x00, 0x00}, m.IdentityHint...)
+		binary.BigEndian.PutUint16(out, uint16(len(out)-2))
+		return out, nil
+	}
+
+	out := []byte{byte(m.EllipticCurveType), 0x00, 0x00}
+	binary.BigEndian.PutUint16(out[1:], uint16(m.NamedCurve))
+
+	out = append(out, byte(len(m.PublicKey)))
+	out = append(out, m.PublicKey...)
+
+	if m.HashAlgorithm == hash.None && m.SignatureAlgorithm == signature.Anonymous && len(m.Signature) == 0 {
+		return out, nil
+	}
+
+	out = append(out, []byte{byte(m.HashAlgorithm), byte(m.SignatureAlgorithm), 0x00, 0x00}...)
+	binary.BigEndian.PutUint16(out[len(out)-2:], uint16(len(m.Signature)))
+	out = append(out, m.Signature...)
+
+	return out, nil
+}
+
+// Unmarshal populates the message from encoded data
+func (m *MessageServerKeyExchange) Unmarshal(data []byte) error {
+	if len(data) < 2 {
+		return errBufferTooSmall
+	}
+
+	// If parsed as PSK return early and only populate PSK Identity Hint
+	if pskLength := binary.BigEndian.Uint16(data); len(data) == int(pskLength+2) {
+		m.IdentityHint = append([]byte{}, data[2:]...)
+		return nil
+	}
+
+	if _, ok := elliptic.CurveTypes()[elliptic.CurveType(data[0])]; ok {
+		m.EllipticCurveType = elliptic.CurveType(data[0])
+	} else {
+		return errInvalidEllipticCurveType
+	}
+
+	if len(data[1:]) < 2 {
+		return errBufferTooSmall
+	}
+	m.NamedCurve = elliptic.Curve(binary.BigEndian.Uint16(data[1:3]))
+	if _, ok := elliptic.Curves()[m.NamedCurve]; !ok {
+		return errInvalidNamedCurve
+	}
+	if len(data) < 4 {
+		return errBufferTooSmall
+	}
+
+	publicKeyLength := int(data[3])
+	offset := 4 + publicKeyLength
+	if len(data) < offset {
+		return errBufferTooSmall
+	}
+	m.PublicKey = append([]byte{}, data[4:offset]...)
+
+	// Anon connection doesn't contains hashAlgorithm, signatureAlgorithm, signature
+	if len(data) == offset {
+		return nil
+	} else if len(data) <= offset {
+		return errBufferTooSmall
+	}
+
+	m.HashAlgorithm = hash.Algorithm(data[offset])
+	if _, ok := hash.Algorithms()[m.HashAlgorithm]; !ok {
+		return errInvalidHashAlgorithm
+	}
+	offset++
+	if len(data) <= offset {
+		return errBufferTooSmall
+	}
+	m.SignatureAlgorithm = signature.Algorithm(data[offset])
+	if _, ok := signature.Algorithms()[m.SignatureAlgorithm]; !ok {
+		return errInvalidSignatureAlgorithm
+	}
+	offset++
+	if len(data) < offset+2 {
+		return errBufferTooSmall
+	}
+	signatureLength := int(binary.BigEndian.Uint16(data[offset:]))
+	offset += 2
+	if len(data) < offset+signatureLength {
+		return errBufferTooSmall
+	}
+	m.Signature = append([]byte{}, data[offset:offset+signatureLength]...)
+	return nil
+}