添加 github.com/pion/dtls 代码

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

@@ -0,0 +1,100 @@
+package handshake
+
+import (
+	"encoding/binary"
+
+	"github.com/pion/dtls/v2/pkg/crypto/clientcertificate"
+	"github.com/pion/dtls/v2/pkg/crypto/hash"
+	"github.com/pion/dtls/v2/pkg/crypto/signature"
+	"github.com/pion/dtls/v2/pkg/crypto/signaturehash"
+)
+
+/*
+MessageCertificateRequest is so a non-anonymous server can optionally
+request a certificate from the client, if appropriate for the selected cipher
+suite.  This message, if sent, will immediately follow the ServerKeyExchange
+message (if it is sent; otherwise, this message follows the
+server's Certificate message).
+
+https://tools.ietf.org/html/rfc5246#section-7.4.4
+*/
+type MessageCertificateRequest struct {
+	CertificateTypes        []clientcertificate.Type
+	SignatureHashAlgorithms []signaturehash.Algorithm
+}
+
+const (
+	messageCertificateRequestMinLength = 5
+)
+
+// Type returns the Handshake Type
+func (m MessageCertificateRequest) Type() Type {
+	return TypeCertificateRequest
+}
+
+// Marshal encodes the Handshake
+func (m *MessageCertificateRequest) Marshal() ([]byte, error) {
+	out := []byte{byte(len(m.CertificateTypes))}
+	for _, v := range m.CertificateTypes {
+		out = append(out, byte(v))
+	}
+
+	out = append(out, []byte{0x00, 0x00}...)
+	binary.BigEndian.PutUint16(out[len(out)-2:], uint16(len(m.SignatureHashAlgorithms)*2))
+	for _, v := range m.SignatureHashAlgorithms {
+		out = append(out, byte(v.Hash))
+		out = append(out, byte(v.Signature))
+	}
+
+	out = append(out, []byte{0x00, 0x00}...) // Distinguished Names Length
+	return out, nil
+}
+
+// Unmarshal populates the message from encoded data
+func (m *MessageCertificateRequest) Unmarshal(data []byte) error {
+	if len(data) < messageCertificateRequestMinLength {
+		return errBufferTooSmall
+	}
+
+	offset := 0
+	certificateTypesLength := int(data[0])
+	offset++
+
+	if (offset + certificateTypesLength) > len(data) {
+		return errBufferTooSmall
+	}
+
+	for i := 0; i < certificateTypesLength; i++ {
+		certType := clientcertificate.Type(data[offset+i])
+		if _, ok := clientcertificate.Types()[certType]; ok {
+			m.CertificateTypes = append(m.CertificateTypes, certType)
+		}
+	}
+	offset += certificateTypesLength
+	if len(data) < offset+2 {
+		return errBufferTooSmall
+	}
+	signatureHashAlgorithmsLength := int(binary.BigEndian.Uint16(data[offset:]))
+	offset += 2
+
+	if (offset + signatureHashAlgorithmsLength) > len(data) {
+		return errBufferTooSmall
+	}
+
+	for i := 0; i < signatureHashAlgorithmsLength; i += 2 {
+		if len(data) < (offset + i + 2) {
+			return errBufferTooSmall
+		}
+		h := hash.Algorithm(data[offset+i])
+		s := signature.Algorithm(data[offset+i+1])
+
+		if _, ok := hash.Algorithms()[h]; !ok {
+			continue
+		} else if _, ok := signature.Algorithms()[s]; !ok {
+			continue
+		}
+		m.SignatureHashAlgorithms = append(m.SignatureHashAlgorithms, signaturehash.Algorithm{Signature: s, Hash: h})
+	}
+
+	return nil
+}