feat: add handle create session (#43)

Signed-off-by: ZhangJian He <shoothzj@gmail.com>

opcua/service_set.go

@@ -2,6 +2,7 @@ package opcua
 
 import (
 	"github.com/protocol-laboratory/opcua-go/opcua/uamsg"
+	"github.com/protocol-laboratory/opcua-go/opcua/util"
 )
 
 func (secChan *SecureChannel) handleOpenSecureChannelRequest(req *uamsg.Message) (*uamsg.Message, error) {
@@ -37,7 +38,54 @@ func (secChan *SecureChannel) handleCreateSessionRequest(req *uamsg.Message) (*u
 	if err != nil {
 		return nil, err
 	}
-	return nil, nil
+	session := newSession(createSessionRequest.SessionName, createSessionRequest.RequestedSessionTimeout, createSessionRequest.MaxResponseMessageSize)
+	token := getUniqueSessionAuthenticationToken()
+
+	rsp := &uamsg.Message{
+		MessageHeader: &uamsg.MessageHeader{
+			MessageType:     uamsg.MsgMessageType,
+			SecureChannelId: &secChan.channelId,
+		},
+		SecurityHeader: &uamsg.SymmetricSecurityHeader{
+			TokenId: secChan.getCurrentTokenId(),
+		},
+		SequenceHeader: &uamsg.SequenceHeader{
+			SequenceNumber: secChan.getNextSequenceNumber(),
+			RequestId:      req.RequestId,
+		},
+		MessageBody: &uamsg.GenericBody{
+			TypeId: &uamsg.ExpandedNodeId{
+				NodeId: &uamsg.ObjectCreateSessionResponse_Encoding_DefaultBinary,
+			},
+			Service: &uamsg.CreateSessionResponse{
+				Header: &uamsg.ResponseHeader{
+					Timestamp:     util.GetCurrentUaTimestamp(),
+					RequestHandle: createSessionRequest.Header.RequestHandle,
+					ServiceResult: uint32(uamsg.ErrorCodeGood),
+					ServiceDiagnostics: &uamsg.DiagnosticInfo{
+						EncodingMask: 0x00,
+					},
+					StringTable: nil,
+					AdditionalHeader: &uamsg.ExtensionObject{
+						TypeId: &uamsg.NodeId{
+							EncodingType: uamsg.TwoByte,
+							Identifier:   byte(0),
+						},
+						Encoding: 0x00,
+					},
+				},
+				SessionId:             &session.sessionId,
+				AuthenticationToken:   token,
+				RevisedSessionTimeout: uamsg.Duration(session.requestedSessionTimeout.Milliseconds()),
+				ServerNonce:           session.serverNonce,
+				MaxRequestMessageSize: session.maxResponseMessageSize,
+				// TODO endpoints description needed
+				// ServerEndpoints: make([]*uamsg.EndpointDescription, 0),
+			},
+		},
+	}
+
+	return rsp, nil
 }
 
 func (secChan *SecureChannel) handleActivateSessionRequest(req *uamsg.Message) (*uamsg.Message, error) {

opcua/session.go

@@ -33,6 +33,7 @@ func getUniqueSessionId() uamsg.NodeId {
 	return uamsg.NodeId{
 		EncodingType: uamsg.GuidType,
 		Namespace:    1,
+		// TODO should create the opcua-guid from a real uuid
 		Identifier: uamsg.Guid{
 			Data1: rand.Uint32(),
 			Data2: uint16(rand.Uint32() % 65535),