winsocket练习一 阻塞与select模型

简单的封装了一下，有很多不完善的地方，很多细节未考虑进去。

client代码

unit ClientMainFormUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, System.Win.ScktComp, Winapi.Winsock,
  Vcl.StdCtrls;

type
  TMyClientSocket = class
  private
    FActive: Boolean;
    FConnected: Boolean;
    FSocketHandle: TSocket;
    FSocketAddr: TSockAddr;
    FSocketRead: TNotifyEvent;
    FSocketWrite: TNotifyEvent;
    procedure SetSocketRead(const Value: TNotifyEvent);
    procedure SetSocketWrite(const Value: TNotifyEvent);
  public
    constructor Create;
    destructor Destroy; override;
    procedure Open(IP: string; Port: Word);
    procedure Close;
    function SendBuf(var Buf; BufSize: Integer): Integer;
    function ReceiveBuf(var Buf; BufSize: Integer): Integer;
    property Active: Boolean read FActive write FActive;
    property SockctRead: TNotifyEvent read FSocketRead write SetSocketRead;
    property SocketWrite: TNotifyEvent read FSocketWrite write SetSocketWrite;
  end;

  TForm2 = class(TForm)
    ClientSocket1: TClientSocket;
    Memo1: TMemo;
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    FCSocket: TMyClientSocket;
    procedure ReadHandle(Sender: TObject);
    procedure WriteHandle(Sender: TObject);
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;



var
  Form2: TForm2;
  WSAData: TWsaData;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
  FCSocket.Open('192.168.1.105', 6000);
end;

constructor TForm2.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  if WSAStartup($0101, WSAData) <> 0 then
    raise Exception.Create('WSAStartup Error');
  FCSocket := TMyClientSocket.Create;
  FCSocket.SockctRead := ReadHandle;
  FCSocket.SocketWrite := WriteHandle;
end;

destructor TForm2.Destroy;
begin
  FCSocket.Free;
  WSACleanup;
  inherited;
end;

procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  FCSocket.Close;
end;

procedure TForm2.ReadHandle(Sender: TObject);
var
  ret: Integer;
  buf: array[0..9] of AnsiChar;
begin
  ret := FCSocket.ReceiveBuf(buf[0], 10);
  if ret > 0 then
    Memo1.Lines.Add(String(AnsiString(buf)));
  if ret = 0 then
    FCSocket.FActive := False;
end;

procedure TForm2.WriteHandle(Sender: TObject);
var
  buf: TBytes;
begin
  buf := BytesOf(DateTimeToStr(Now));
  FCSocket.SendBuf(buf, Length(buf));
end;

{ TClientSkt }

constructor TMyClientSocket.Create;
begin
  inherited Create;
  FActive := False;
  FConnected := False;
  FSocketHandle := INVALID_SOCKET;
end;

destructor TMyClientSocket.Destroy;
begin
  if FConnected then
    Close;
  inherited;
end;

procedure TMyClientSocket.Open(IP: string; Port: Word);
var
  c, ErrorCode: Integer;
  FDSet: TFDSet;
  TimeVal: TTimeVal;
begin
  FSocketAddr.sin_family := PF_INET;
  FSocketAddr.sin_port := htons(Port);
  FSocketAddr.sin_addr.S_addr := inet_addr(PAnsiChar(AnsiString(IP)));
  FSocketHandle := socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
  if FSocketHandle = INVALID_SOCKET then
    raise Exception.Create('Cannot Create Socket');
  if connect(FSocketHandle, FSocketAddr, SizeOf(FSocketAddr)) = SOCKET_ERROR then
    raise Exception.Create(SysErrorMessage(WSAGetLastError));

  FConnected := FSocketHandle <> INVALID_SOCKET;

  TimeVal.tv_sec := 0;
  TimeVal.tv_usec := 500;
  FActive := True;
  while FActive do
  begin
    FD_ZERO(FDSet);
    FD_SET(FSocketHandle, FDSet);
    c := select(0, @FDSet, nil, nil, @TimeVal);
    case c of
      SOCKET_ERROR:
        raise Exception.Create('Select Error');
      0:
        Break; //超时，一般是服务端关闭了 。
      else
        if FD_ISSET(FSocketHandle, FDSet) and Assigned(FSocketRead) then
          FSocketRead(Self);
    end;

    Application.ProcessMessages;

    FD_ZERO(FDSet);
    FD_SET(FSocketHandle, FDSet);
    c := select(0, nil, @FDSet, nil, @TimeVal);
    case c of
      SOCKET_ERROR:
        raise Exception.Create(SysErrorMessage(WSAGetLastError)+ ' code: '+WSAGetLastError.ToString);
      0:
        Break;
      else
        if FD_ISSET(FSocketHandle, FDSet) then
        begin
          if Assigned(FSocketWrite) then
            FSocketWrite(Self);
        end;
    end;

{
  在《windows网络编程》一书中说，可以用 getsockopt, SO_ERROR 获取错误信息
  但 winsock 对 SO_ERROR 支持的可能并不一致。书中提到还可以用 recv , recvfrom
  确定是否失败，然后用 WSAGetLastError 获取错误信息。 但这种方法 也不是万无一失的。
}

//    FD_ZERO(FDSet);
//    FD_SET(FSocketHandle, FDSet);
//    c := select(0, nil, nil, @FDSet, @TimeVal);
//    case c of
//      SOCKET_ERROR:
//        raise Exception.Create('Select Error');
//      0:
//        Break;
//      else
//        if FD_ISSET(FSocketHandle, FDSet) then
//          raise Exception.Create('Error Message');
//    end;

    Application.ProcessMessages;
  end;
end;

function TMyClientSocket.ReceiveBuf(var Buf; BufSize: Integer): Integer;
begin
  Result := recv(FSocketHandle, buf, BufSize, 0);
end;

function TMyClientSocket.SendBuf(var Buf; BufSize: Integer): Integer;
begin
  Result := send(FSocketHandle, buf, BufSize, 0);
end;

procedure TMyClientSocket.SetSocketRead(const Value: TNotifyEvent);
begin
  FSocketRead := Value;
end;

procedure TMyClientSocket.SetSocketWrite(const Value: TNotifyEvent);
begin
  FSocketWrite := Value;
end;

procedure TMyClientSocket.Close;
begin
  FActive := False;

  if FConnected then
  begin
//    shutdown(FSocketHandle, 2);
    if closesocket(FSocketHandle) = SOCKET_ERROR then
      raise Exception.Create(SysErrorMessage(WSAGetLastError));
    FConnected := False;
  end;
end;


end.

Server代码

unit ServerMainFormUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, System.Win.ScktComp, Winapi.WinSock;

type
  TMyServerSocket = class
  private
    FPort: Word;
    FActive: Boolean;
    FSocketHandle: TSocket;
    FSocketAddr: TSockAddr;
  public
    constructor Create;
    destructor Destroy; override;
    procedure Open;
    procedure Close;
    property Port: Word read FPort write FPort;
  end;

  TForm2 = class(TForm)
    ServerSocket1: TServerSocket;
    Memo1: TMemo;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    FSSocket: TMyServerSocket;
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
  FSSocket.Open;
end;

procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  FSSocket.Close;
end;

procedure TForm2.FormCreate(Sender: TObject);
var
  wsData: TWSAData;
begin
  WSAStartup($0101, wsData);
  FSSocket := TMyServerSocket.Create;
  FSSocket.Port := 6000;
end;


{ TClientSkt }

constructor TMyServerSocket.Create;
begin
  inherited Create;
  FActive := False;
  FSocketHandle := INVALID_SOCKET;
end;

destructor TMyServerSocket.Destroy;
begin
  Close;
  inherited;
end;

procedure TMyServerSocket.Open;
var
  c: Integer;
  FDSet: TFDSet;
  ClientAddr: TSockAddr;
  ClientAddrSize: Integer;
  ClientSocket: TSocket;
  TimeVal: TTimeVal;
  buf: TBytes;
begin
  FSocketAddr.sin_family := PF_INET;
  FSocketAddr.sin_port := htons(Port);
  FSocketAddr.sin_addr.S_addr := INADDR_ANY;
  FSocketHandle := socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
  if FSocketHandle = INVALID_SOCKET then
    raise Exception.Create('Cannot Create Socket');

  bind(FSocketHandle, FSocketAddr, SizeOf(FSocketAddr));
  {
    listen(socket s, int backlog)
    backlog 参数指定搁置连接的最大数， 如果为2， 那么当有三个连接请求时，
    前两个连接请求会被 ”挂起 " ,第三个连接请求会失败，返回 WSAECONNREFUSED 错误。
  }
  FActive := listen(FSocketHandle, 2) = 0;

  if not FActive then
    raise Exception.Create(SysErrorMessage(WSAGetLastError));

  TimeVal.tv_sec := 0;
  TimeVal.tv_usec := 100;
  FActive := True;
  while FActive do
  begin
    FD_ZERO(FDSet);
    FD_SET(FSocketHandle, FDSet);
    c := select(0, @FDSet, nil, nil, @TimeVal);
    case c of
      SOCKET_ERROR:
        ;
      0:
        Application.ProcessMessages;
      else
        if FD_ISSET(FSocketHandle, FDSet) then
        begin
          ClientSocket := accept(FSocketHandle, @ClientAddr, @ClientAddrSize);
          if (ClientSocket <> INVALID_SOCKET) then
          begin
            buf := BytesOf('hello');
            send(ClientSocket, buf[0], Length(buf), 0);
            Application.ProcessMessages;
            shutdown(ClientSocket, 1);
            closesocket(ClientSocket);
          end;
        end;
    end;

    Application.ProcessMessages;
  end;
end;

procedure TMyServerSocket.Close;
begin
  if FActive then
  begin
    shutdown(FSocketHandle, 1);
    closesocket(FSocketHandle);
    FActive := False;
  end;
end;

procedure TForm2.FormDestroy(Sender: TObject);
begin
  FSSocket.Close;
  FSSocket.Free;
  WSACleanup;
end;

end.

如何优雅的关闭socket，还需要很多测试。

目前看，send和recv 后立即断开连接时，在closesocket前，需要立即 shutdown 或 setsockopt  SO_LINGER 相对稳定。

此外，send 或 recv 后返回 0，基本上表示socket 被断开了。