Gurux.DLMS.GXDLMS.GetSNPdu C# (CSharp) Method

        internal static void GetSNPdu(GXDLMSSNParameters p, GXByteBuffer reply)
        {
            bool ciphering = p.settings.Cipher != null && p.settings.Cipher.Security != Gurux.DLMS.Enums.Security.None;
            if (!ciphering && p.settings.InterfaceType == InterfaceType.HDLC)
            {
                if (p.settings.IsServer)
                {
                    reply.Set(GXCommon.LLCReplyBytes);
                }
                else if (reply.Size == 0)
                {
                    reply.Set(GXCommon.LLCSendBytes);
                }
            }
            int cnt = 0, cipherSize = 0;
            if (ciphering)
            {
                cipherSize = CipheringHeaderSize;
                /*
                if (p.settings.Cipher.Security == Security.Encryption)
                {
                    cipherSize = 7;
                }
                else if (p.settings.Cipher.Security == Security.Authentication)
                {
                    cipherSize = 19;
                }
                else if (p.settings.Cipher.Security == Security.AuthenticationEncryption)
                {
                    cipherSize = 7;
                }
                 * */
            }
            if (p.data != null)
            {
                cnt = p.data.Size - p.data.Position;
            }
            // Add command.
            if (p.command != Command.Aarq && p.command != Command.Aare)
            {
                reply.SetUInt8((byte)p.command);
                if (p.count != 0xFF)
                {
                    GXCommon.SetObjectCount(p.count, reply);
                }
                if (p.requestType != 0xFF)
                {
                    reply.SetUInt8(p.requestType);
                }
                reply.Set(p.attributeDescriptor);

                if (!p.multipleBlocks)
                {
                    p.multipleBlocks = reply.Size + cipherSize + cnt > p.settings.MaxPduSize;
                    //If reply data is not fit to one PDU.
                    if (p.multipleBlocks)
                    {
                        //Remove command.
                        GXByteBuffer tmp = new GXByteBuffer();
                        int offset = 1;
                        if (!ciphering && p.settings.InterfaceType == InterfaceType.HDLC)
                        {
                            offset = 4;
                        }
                        tmp.Set(reply.Data, offset, reply.Size - offset);
                        reply.Size = 0;
                        if (!ciphering && p.settings.InterfaceType == InterfaceType.HDLC)
                        {
                            if (p.settings.IsServer)
                            {
                                reply.Set(GXCommon.LLCReplyBytes);
                            }
                            else if (reply.Size == 0)
                            {
                                reply.Set(GXCommon.LLCSendBytes);
                            }
                        }
                        if (p.command == Command.WriteRequest)
                        {
                            p.requestType = (byte)VariableAccessSpecification.WriteDataBlockAccess;
                        }
                        else if (p.command == Command.ReadRequest)
                        {
                            p.requestType = (byte)VariableAccessSpecification.ReadDataBlockAccess;
                        }
                        else if (p.command == Command.ReadResponse)
                        {
                            p.requestType = (byte)SingleReadResponse.DataBlockResult;
                        }
                        else
                        {
                            throw new ArgumentException("Invalid command.");
                        }
                        reply.SetUInt8((byte)p.command);
                        //Set object count.
                        reply.SetUInt8(1);
                        if (p.requestType != 0xFF)
                        {
                            reply.SetUInt8(p.requestType);
                        }
                        cnt = GXDLMS.AppendMultipleSNBlocks(p, tmp, reply);
                    }
                }
                else
                {
                    cnt = GXDLMS.AppendMultipleSNBlocks(p, null, reply);
                }
            }
            // Add data.
            reply.Set(p.data, cnt);
            //Af all data is transfered.
            if (p.data != null && p.data.Position == p.data.Size)
            {
                p.settings.Index = p.settings.Count = 0;
            }
            // If Ciphering is used.
            if (ciphering && p.command != Command.Aarq && p.command != Command.Aare)
            {
                byte[] tmp = p.settings.Cipher.Encrypt((byte)GetGloMessage(p.command), p.settings.Cipher.SystemTitle, reply.Array());
                System.Diagnostics.Debug.Assert(!(p.settings.MaxPduSize < tmp.Length));
                reply.Size = 0;
                if (p.settings.InterfaceType == InterfaceType.HDLC)
                {
                    if (p.settings.IsServer)
                    {
                        reply.Set(GXCommon.LLCReplyBytes);
                    }
                    else if (reply.Size == 0)
                    {
                        reply.Set(GXCommon.LLCSendBytes);
                    }
                }
                reply.Set(tmp);
            }
        }