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/* X224.h
* * Copyright (c) 1994-1995 by DataBeam Corporation, Lexington, KY * * Abstract: * This class represents the X.224 class 0 Transport functionality. This * is the highest layer in the T.123 specification. This layer is unique * in that it has direct access to the User. When data packets are * received from the remote site and reassembled by this class, they are * passed on to the user via a callback. * * This class has only limited functionality. It basically has a simple * link establishment procedure (which includes arbitration of maximum PDU * size). It is then responsible for transmitting and receiving user data. * Its maximum TSDU size is 8K, and its TPDU size can range from 128 bytes * to 2K. Its TSDU size is larger than its TPDU size, it must be able to * segment and reassemble the user packet. * * This layer ASSUMES that its lower layer has a packet interface rather * than a stream interface. * * This layer ASSUMES that the disconnect of a call is handled by the * Network layer (as specified in the X.224 class 0 document). * * Prior knowledge of the X.224 class 0 specification would help the user * understand the code. * * Caveats: * None. * * Authors: * James W. Lawwill */
#ifndef _X224_H_
#define _X224_H_
#include "tmemory2.h"
/*
** The following, are states that the class can be in. */typedef enum{ NO_CONNECTION, SENT_CONNECT_REQUEST_PACKET, SENT_CONNECT_CONFIRM_PACKET, SENT_DISCONNECT_REQUEST_PACKET, SENT_ERROR_PACKET, CONNECTION_ACTIVE, RECEIVED_CONNECT_REQUEST_PACKET, FAILED_TO_INITIALIZE} X224State;
#define TRANSPORT_HASHING_BUCKETS 3
/*
** Packet types */#define TPDU_CODE_MASK 0xf0
#define TRANSPORT_NO_PACKET 0x00
#define CONNECTION_REQUEST_PACKET 0xe0
#define CONNECTION_CONFIRM_PACKET 0xd0
#define DISCONNECT_REQUEST_PACKET 0x80
#define ERROR_PACKET 0x70
#define DATA_PACKET 0xf0
#define TSAP_CALLING_IDENTIFIER 0xc1
#define TSAP_CALLED_IDENTIFIER 0xc2
#define TPDU_SIZE 0xc0
/*
** These defines are used for the ERROR packet */#define INVALID_TPDU 0xc1
/*
** Packet size codes */#define PACKET_SIZE_128 0x07
#define PACKET_SIZE_256 0x08
#define PACKET_SIZE_512 0x09
#define PACKET_SIZE_1024 0x0a
#define PACKET_SIZE_2048 0x0b
/*
** Miscellaneous definitions */#define MAXIMUM_USER_DATA_SIZE 8192
#define DATA_PACKET_HEADER_SIZE 3
#define EOT_BIT 0x80
#define CONNECT_REQUEST_HEADER_SIZE 6
#define CONNECT_CONFIRM_HEADER_SIZE 6
#define DISCONNECT_REQUEST_HEADER_SIZE 6
#define ERROR_HEADER_SIZE 6
#define TPDU_ARBITRATION_PACKET_SIZE 3
#define DISCONNECT_REASON_NOT_SPECIFIED 0
typedef SListClass DataRequestQueue;typedef SListClass PacketQueue;
class CLayerX224 : public IProtocolLayer{public:
CLayerX224( T123 *owner_object, CLayerQ922 *lower_layer, USHORT message_base, LogicalHandle logical_handle, ULONG identifier, USHORT data_indication_queue_size, USHORT default_PDU_size, PMemoryManager dr_memory_manager, BOOL *initialization_success);
virtual ~CLayerX224(void);
/*
** Making and breaking links */ TransportError ConnectRequest (void); TransportError ConnectResponse (void); TransportError DisconnectRequest (void);
/*
** Functions overridden from the ProtocolLayer object */ ProtocolLayerError DataRequest ( ULONG_PTR identifier, LPBYTE buffer_address, ULONG length, PULong bytes_accepted); ProtocolLayerError DataRequest ( ULONG_PTR identifier, PMemory, PULong bytes_accepted); ProtocolLayerError DataIndication ( LPBYTE buffer_address, ULONG length, PULong bytes_accepted); ProtocolLayerError RegisterHigherLayer ( ULONG_PTR, PMemoryManager, IProtocolLayer *); ProtocolLayerError RemoveHigherLayer ( ULONG_PTR); ProtocolLayerError PollTransmitter ( ULONG_PTR identifier, USHORT data_to_transmit, USHORT * pending_data, USHORT * holding_data); ProtocolLayerError PollReceiver(void); ProtocolLayerError GetParameters ( USHORT *, USHORT *, USHORT *);
void ShutdownReceiver (void); void EnableReceiver (void); void ShutdownTransmitter (void); void PurgeRequest (void); void CheckUserBuffers (void);static ULONG GetMaxTPDUSize ( ULONG max_lower_layer_pdu);
private:
BOOL AllocateBuffers (void); void ErrorPacket ( LPBYTE packet_address, USHORT packet_length);private:
DataRequestQueue Data_Request_Queue; PacketQueue Data_Indication_Queue; PacketQueue Data_Indication_Memory_Pool;
PTMemory Active_Data_Indication; T123 *m_pT123; // owner object
CLayerQ922 *m_pQ922; // lower layer;
USHORT m_nMsgBase; USHORT Default_PDU_Size; USHORT Maximum_PDU_Size; USHORT Arbitrated_PDU_Size; ULONG Identifier; PMemoryManager Data_Request_Memory_Manager; USHORT Lower_Layer_Prepend; USHORT Lower_Layer_Append; ULONG User_Data_Pending;
USHORT Data_Indication_Queue_Size; BOOL Data_Indication_Reassembly_Active;
X224State State; USHORT Packet_Pending; UChar Reject_Cause; BOOL Packet_Size_Respond; BOOL Shutdown_Receiver; BOOL Shutdown_Transmitter;
LPBYTE Error_Buffer; USHORT Error_Buffer_Length;
LogicalHandle m_nLocalLogicalHandle; LogicalHandle m_nRemoteLogicalHandle;};
#endif
/*
* Documentation for Public class members */
/*
* Transport::Transport ( * PTransportResources transport_resources, * IObject * owner_object, * IProtocolLayer * lower_layer, * USHORT message_base, * USHORT logical_handle, * USHORT identifier, * USHORT data_request_queue_size, * USHORT data_indication_queue_size, * USHORT default_PDU_size, * PMemoryManager dr_memory_manager, * BOOL * initialization_success); * * Functional Description * This is the class constructor. During construction, this object * registers itself with its lower layer and allocates buffer space for * sending and receiving data. * * Formal Parameters * transport_resources (i) - Pointer to TransportResources structure. * owner_object (i) - Address of owner object. We use this * address for owner callbacks. * lower_layer (i) - Address of the lower layer that we will use * for data reception and transmission. This * layer must inherit from ProtocolLayer. * message_base (i) - Message base for messages used for owner * callbacks. * logical_handle (i) - This identification must be passed back to * the owner during owner callbacks to identify * itself. * identifier (i) - This identifier is passed to the lower layer * to identify itself (in case the lower layer * is doing multiplexing. * data_request_queue_size (i) - Number of buffers to be used for data * requests from user. * data_indication_queue_size (i) - Number of buffers to be used for * data requests from user. * default_PDU_size (i) - If the remote site does not support packet * size arbitration, this is the default * dr_memory_manager (i) - Data Request memory manager * initialization_success (o) - Return TRUE if initialization was * successful * * Return Value * None * * Side Effects * None * * Caveats * None * */
/*
* Transport::~Transport (void) * * Functional Description * This is the destructor for the class. It does all cleanup * * Formal Parameters * None * * Return Value * None * * Side Effects * None * * Caveats * None * */
/*
* TransportError Transport::ConnectRequest (void); * * Functional Description * This function is called to initiate the connection. As a result the * owner will either receive a TRANSPORT_CONNECT_CONFIRM or a * TRANSPORT_DISCONNECT_INDICATION message on completion of arbitration. * * Formal Parameters * None * * Return Value * TRANSPORT_NO_ERROR - No error occured * TRANSPORT_ERROR - Error * * Side Effects * None * * Caveats * None * */
/*
* TransportError Transport::ConnectResponse (void); * * Functional Description * This function is called in response to a TRANSPORT_CONNECT_INDICATION * message issued by this class. By calling this function, the user is * accepting the transport connection. * * Formal Parameters * None * * Return Value * TRANSPORT_NO_ERROR - No error occured * TRANSPORT_ERROR - Error * * Side Effects * None * * Caveats * None * */
/*
* TransportError Transport::DisconnectRequest (void); * * Functional Description * This function is called in response to a TRANSPORT_CONNECT_INDICATION * message issued by this class. By calling this function, the user is * not accepting the transport connection. * * Formal Parameters * None * * Return Value * TRANSPORT_NO_ERROR - No error occured * TRANSPORT_ERROR - Error * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Transport::DataRequest ( * USHORT identifier, * LPBYTE buffer_address, * USHORT length, * USHORT * bytes_accepted); * * Functional Description * This function is called by a higher layer to request transmission of * a packet. * * Formal Parameters * identifier (i) - Identifier of the higher layer * buffer_address (i) - Buffer address * length (i) - Length of packet to transmit * bytes_accepted (o) - Number of bytes accepted by the Transport. * This value will either be 0 or the packet * length since this layer is a packet to byte * converter. * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Transport::DataIndication ( * LPBYTE buffer_address, * USHORT length, * USHORT * bytes_accepted); * * Functional Description * This function is called by the lower layer when it has data to pass up * * Formal Parameters * buffer_address (i) - Buffer address * length (i) - Number of bytes available * bytes_accepted (o) - Number of bytes accepted * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Transport::RegisterHigherLayer ( * USHORT, * IProtocolLayer *); * * Functional Description * This function is called by the higher layer to register its identifier * and its address. This function is not used by this class. It is only * in here because this class inherits from ProtocolLayer and this function * is a pure virtual function. * * Formal Parameters * None used * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Transport::RemoveHigherLayer ( * USHORT); * * Functional Description * This function is called by the higher layer to remove its identifier * and its address. This function is not used by this class. It is only * in here because this class inherits from ProtocolLayer and this function * is a pure virtual function. * * Formal Parameters * None used * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None */
/*
* ProtocolLayerError Transport::PollTransmitter ( * USHORT, * USHORT data_to_transmit, * USHORT * pending_data, * USHORT *) * * Functional Description * This function is called to give the Transport a chance transmit data * in its Data_Request buffer. * * Formal Parameters * identifier (i) - Not used * data_to_transmit (i) - This is a mask that tells us to send Control * data, User data, or both. Since the * Transport does not differentiate between * data types it transmits any data it has * pending_data (o) - Return value to indicate which data is left * to be transmitted. * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None * */
/*
* ProtocolLayerError Transport::PollReceiver ( * USHORT identifier); * * Functional Description * This function is called to give the Transport a chance pass packets * to higher layers * * Formal Parameters * identifier (i) - Not used * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None */
/*
* ProtocolLayerError Transport::GetParameters ( * USHORT identifier, * USHORT * max_packet_size, * USHORT * prepend, * USHORT * append); * * Functional Description: * This function is not used by this class. It is only in here because * this class inherits from ProtocolLayer and this function * is a pure virtual function. * * Formal Parameters * None used * * Return Value * PROTOCOL_LAYER_NO_ERROR - No error occured * * Side Effects * None * * Caveats * None */
/*
* void Transport::ShutdownReceiver (); * * Functional Description: * This function tells the object to stop accepting packets from the * lower layer * * Formal Parameters * None used * * Return Value * None * * Side Effects * None * * Caveats * None */
/*
* void Transport::EnableReceiver (void); * * Functional Description: * This function tells the object to start sending packets up to the user * again. If the X224 object ever issues a DATA_INDICATION and it fails, * we shutdown the receiver. We wait for this call to be issued before * we start sending up packets again. * * Formal Parameters * None used * * Return Value * None * * Side Effects * None * * Caveats * None */
/*
* void Transport::ShutdownTransmitter (void); * * Functional Description: * This function tells the object to stop accepting packets from * higher layers. * * Formal Parameters * None used * * Return Value * None * * Side Effects * None * * Caveats * None */
/*
* void Transport::PurgeRequest (void); * * Functional Description: * This function removes all packets from the Transport's outbound queue * * Formal Parameters * None used * * Return Value * None * * Side Effects * None * * Caveats * None */
/*
* void Transport::CheckUserBuffers (void); * * Functional Description: * This function determines if the user has recently failed to pass a * packet down to the Transport because we didn't have enough memory * available to handle it. If he did and we NOW have space for that * packet, we will issue a TRANSPORT_BUFFER_EMPTY_INDICATION callback * to the user, to notify him that we can accept it. * * Formal Parameters * None used * * Return Value * None * * Side Effects * None * * Caveats * None */
/*
* static ULONG Transport::GetMaxTPDUSize ( * ULONG max_lower_layer_pdu) * * Public * * Functional Description: * This function accepts a value for the lower layer max. PDU size * and returns the max. PDU size that this Transport can support * based on it. X224 only suports max PDU sizes of 128, 256, 512, * 1024, and 2048. So, if the max_lower_layer_pdu is 260, the * Transport can only have a max pdu size of 256. * * Formal Parameters * max_lower_layer_pdu - Since we pass data to the lower layer, * we must conform to its max packet size. * * Return Value * The largest TPDU that we will send based on the max_lower_layer_pdu. * * Side Effects * None * * Caveats * None */
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