【UEFI基础】UEFI网络框架之TCP4

以你之姓@ 2023-10-17 09:30 143阅读 0赞

## TCP ##

TCP全称是Transmission Control Protocol。

TCP是传输层的协议。

这里以TCP4作为研究的对象。

TCP4驱动依赖于IP4。

TCP4驱动主要做了以下的事情：

1. 初始化TCP4\_SERVICE\_DATA结构体，最主要的是为该结构体的成员（IpIo）创建IP4的实例；（使用了IpIoCreate()和IpIoOpen()函数）

2. 创建全局的定时器mTcp4Timer，该定时器定时执行TcpTickingDpc()函数，它处理一大堆超时函数：

TCP_TIMER_HANDLER mTcpTimerHandler[TCP_TIMER_NUMBER] = {
      TcpConnectTimeout,
      TcpRexmitTimeout,
      TcpProbeTimeout,
      TcpKeepaliveTimeout,
      TcpFinwait2Timeout,
      Tcp2MSLTimeout,
    };

也处理应答：

TcpSendAck (Tcb);

3. 安装gEfiTcp4ServiceBindingProtocolGuid对应的Protocol（说明下，这里的Protocol是指UEFI框架下的Protocol并不是指TCP这样的网络“协议”）。

同之前的IP4，MNP等一样，后面的内容需要先介绍几个重要的结构体。

## TCP4\_SERVICE\_DATA structure ##

TCP4\_SERVICE\_DATA定义在Tcp4Driver.h中，如下所示：

typedef struct _TCP4_SERVICE_DATA {
      UINT32                        Signature;
      EFI_HANDLE                    ControllerHandle;
      IP_IO                         *IpIo;  // IP Io consumed by TCP4
      EFI_SERVICE_BINDING_PROTOCOL  Tcp4ServiceBinding;
      EFI_HANDLE                    DriverBindingHandle;
      LIST_ENTRY                    SocketList;
    } TCP4_SERVICE_DATA;

1. **Signature**的值是SIGNATURE\_32 ('T', 'C', 'P', '4')；

2. **ControllerHandle**，**DriverBindingHandle**分别对应EFI\_DRIVER\_BINDING\_PROTOCOL中的ImageHandle和DriverBindingHandle；

3. **IpIo**指向IP4实例，后续会仔细介绍；

4. **Tcp4ServiceBinding**上绑定着TCP4对应的ServiceBindingProtocol；

5. **SocketList**用来存放SOCKET结构体，它在Tcp4CreateSocketCallback()函数中被插入到SocketList链表中，在SockCreate()函数被调用时，会执行前述的Callback函数，而最终是在ServiceBindingProtocol的CreateChild函数Tcp4ServiceBindingCreateChild()中创建的Socket；

Socket实际上表示是网络通信的端点，在通过Tcp4ServiceBindingCreateChild()创建子例的时候，其实就是在创建Socket，所以所有Tcp4提供的接口：

EFI_TCP4_PROTOCOL mTcp4ProtocolTemplate = {
      Tcp4GetModeData,
      Tcp4Configure,
      Tcp4Routes,
      Tcp4Connect,
      Tcp4Accept,
      Tcp4Transmit,
      Tcp4Receive,
      Tcp4Close,
      Tcp4Cancel,
      Tcp4Poll
    };

**其实最终都是使用了Socket**！

## IP\_IO structure ##

IP\_IO定义在IpIoLib.h文件中，如下所示：

typedef struct _IP_IO {
      ///
      /// The node used to link this IpIo to the active IpIo list.
      ///
      LIST_ENTRY                    Entry;
    
      ///
      /// The list used to maintain the IP instance for different sending purpose.
      ///
      LIST_ENTRY                    IpList;
      
      EFI_HANDLE                    Controller;
      EFI_HANDLE                    Image;
      EFI_HANDLE                    ChildHandle;
      //
      // The IP instance consumed by this IP_IO
      //
      IP_IO_IP_PROTOCOL             Ip;
      BOOLEAN                       IsConfigured;
    
      ///
      /// Some ip configuration data can be changed.
      ///
      UINT8                         Protocol;
    
      ///
      /// Token and event used to get data from IP.
      ///
      IP_IO_IP_COMPLETION_TOKEN     RcvToken; 
    
      ///
      /// List entry used to link the token passed to IP_IO.
      ///
      LIST_ENTRY                    PendingSndList;
    
      //
      // User interface used to get notify from IP_IO
      //
      VOID                          *RcvdContext;    ///< See IP_IO_OPEN_DATA::RcvdContext.
      VOID                          *SndContext;     ///< See IP_IO_OPEN_DATA::SndContext.
      PKT_RCVD_NOTIFY               PktRcvdNotify;   ///< See IP_IO_OPEN_DATA::PktRcvdNotify.
      PKT_SENT_NOTIFY               PktSentNotify;   ///< See IP_IO_OPEN_DATA::PktSentNotify.
      UINT8                         IpVersion;
    } IP_IO

IpIoLib实际上就管理了所有的IP4/IP6的操作。

## SOCKET structure ##

SOCKET结构体定义在Socket.h文件中，如下所示：

struct _SOCKET {
    
      //
      // Socket description information
      //
      UINT32                Signature;      ///< Signature of the socket
      EFI_HANDLE            SockHandle;     ///< The virtual handle of the socket
      EFI_HANDLE            DriverBinding;  ///< Socket's driver binding protocol
      EFI_DEVICE_PATH_PROTOCOL  *ParentDevicePath;
      EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
      LIST_ENTRY                Link;  
      UINT8                 ConfigureState;
      SOCK_TYPE             Type;
      UINT8                 State;
      UINT16                Flag;
      EFI_LOCK              Lock;       ///< The lock of socket
      SOCK_BUFFER           SndBuffer;  ///< Send buffer of application's data
      SOCK_BUFFER           RcvBuffer;  ///< Receive buffer of received data
      EFI_STATUS            SockError;  ///< The error returned by low layer protocol
      BOOLEAN               InDestroy;
    
      //
      // Fields used to manage the connection request
      //
      UINT32          BackLog;        ///< the limit of connection to this socket
      UINT32          ConnCnt;        ///< the current count of connections to it
      SOCKET          *Parent;        ///< listening parent that accept the connection
      LIST_ENTRY      ConnectionList; ///< the connections maintained by this socket
      
      //
      // The queue to buffer application's asynchronous token
      //
      LIST_ENTRY      ListenTokenList;
      LIST_ENTRY      RcvTokenList;
      LIST_ENTRY      SndTokenList;
      LIST_ENTRY      ProcessingSndTokenList;
    
      SOCK_COMPLETION_TOKEN *ConnectionToken; ///< app's token to signal if connected
      SOCK_COMPLETION_TOKEN *CloseToken;      ///< app's token to signal if closed
    
      //
      // Interface for low level protocol
      //
      SOCK_PROTO_HANDLER    ProtoHandler;       ///< The request handler of protocol
      UINT8 ProtoReserved[PROTO_RESERVED_LEN];  ///< Data fields reserved for protocol
      NET_PROTOCOL          NetProtocol;        ///< TCP or UDP protocol socket used
    
      //
      // Callbacks after socket is created and before socket is to be destroyed.
      //
      SOCK_CREATE_CALLBACK   CreateCallback;    ///< Callback after created
      SOCK_DESTROY_CALLBACK  DestroyCallback;   ///< Callback before destroied
      VOID                   *Context;          ///< The context of the callback
    };