添加 github.com/pion/dtls 代码

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

@@ -0,0 +1,130 @@
+package handshake
+
+import (
+	"encoding/binary"
+
+	"github.com/pion/dtls/v2/pkg/protocol"
+	"github.com/pion/dtls/v2/pkg/protocol/extension"
+)
+
+/*
+MessageClientHello is for when a client first connects to a server it is
+required to send the client hello as its first message.  The client can also send a
+client hello in response to a hello request or on its own
+initiative in order to renegotiate the security parameters in an
+existing connection.
+*/
+type MessageClientHello struct {
+	Version protocol.Version
+	Random  Random
+	Cookie  []byte
+
+	SessionID []byte // TODO 添加anylink支持
+
+	CipherSuiteIDs     []uint16
+	CompressionMethods []*protocol.CompressionMethod
+	Extensions         []extension.Extension
+}
+
+const handshakeMessageClientHelloVariableWidthStart = 34
+
+// Type returns the Handshake Type
+func (m MessageClientHello) Type() Type {
+	return TypeClientHello
+}
+
+// Marshal encodes the Handshake
+func (m *MessageClientHello) Marshal() ([]byte, error) {
+	if len(m.Cookie) > 255 {
+		return nil, errCookieTooLong
+	}
+
+	out := make([]byte, handshakeMessageClientHelloVariableWidthStart)
+	out[0] = m.Version.Major
+	out[1] = m.Version.Minor
+
+	rand := m.Random.MarshalFixed()
+	copy(out[2:], rand[:])
+
+	out = append(out, 0x00) // SessionID
+
+	out = append(out, byte(len(m.Cookie)))
+	out = append(out, m.Cookie...)
+	out = append(out, encodeCipherSuiteIDs(m.CipherSuiteIDs)...)
+	out = append(out, protocol.EncodeCompressionMethods(m.CompressionMethods)...)
+
+	extensions, err := extension.Marshal(m.Extensions)
+	if err != nil {
+		return nil, err
+	}
+
+	return append(out, extensions...), nil
+}
+
+// Unmarshal populates the message from encoded data
+func (m *MessageClientHello) Unmarshal(data []byte) error {
+	if len(data) < 2+RandomLength {
+		return errBufferTooSmall
+	}
+
+	m.Version.Major = data[0]
+	m.Version.Minor = data[1]
+
+	var random [RandomLength]byte
+	copy(random[:], data[2:])
+	m.Random.UnmarshalFixed(random)
+
+	// rest of packet has variable width sections
+	currOffset := handshakeMessageClientHelloVariableWidthStart
+	currOffset += int(data[currOffset]) + 1 // SessionID
+
+	// TODO 添加SessionID
+	m.SessionID = data[handshakeMessageClientHelloVariableWidthStart+1 : currOffset]
+
+	currOffset++
+	if len(data) <= currOffset {
+		return errBufferTooSmall
+	}
+	n := int(data[currOffset-1])
+	if len(data) <= currOffset+n {
+		return errBufferTooSmall
+	}
+	m.Cookie = append([]byte{}, data[currOffset:currOffset+n]...)
+	currOffset += len(m.Cookie)
+
+	// Cipher Suites
+	if len(data) < currOffset {
+		return errBufferTooSmall
+	}
+	cipherSuiteIDs, err := decodeCipherSuiteIDs(data[currOffset:])
+	if err != nil {
+		return err
+	}
+	m.CipherSuiteIDs = cipherSuiteIDs
+	if len(data) < currOffset+2 {
+		return errBufferTooSmall
+	}
+	currOffset += int(binary.BigEndian.Uint16(data[currOffset:])) + 2
+
+	// Compression Methods
+	if len(data) < currOffset {
+		return errBufferTooSmall
+	}
+	compressionMethods, err := protocol.DecodeCompressionMethods(data[currOffset:])
+	if err != nil {
+		return err
+	}
+	m.CompressionMethods = compressionMethods
+	if len(data) < currOffset {
+		return errBufferTooSmall
+	}
+	currOffset += int(data[currOffset]) + 1
+
+	// Extensions
+	extensions, err := extension.Unmarshal(data[currOffset:])
+	if err != nil {
+		return err
+	}
+	m.Extensions = extensions
+	return nil
+}