server.pas

网络路径中信息发送的gobackn地实现

unit server;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ScktComp, ComCtrls;

type
  TForm1 = class(TForm)
    ServerSocket1: TServerSocket;
    Memo1: TMemo;
    StatusBar1: TStatusBar;
    ListBox1: TListBox;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
 //   procedure FormCreate(Sender: TObject);
    procedure ServerSocket1Listen(Sender: TObject;
      Socket: TCustomWinSocket);
    procedure ServerSocket1Accept(Sender: TObject;
      Socket: TCustomWinSocket);
    procedure ServerSocket1ClientRead(Sender: TObject;
      Socket: TCustomWinSocket);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  expect_no:string;
  corrupt:boolean;
  loss:boolean;
implementation

{$R *.dfm}


procedure TForm1.ServerSocket1Listen(Sender: TObject;
  Socket: TCustomWinSocket);
begin
    StatusBar1.SimpleText := '监听...';
end;

procedure TForm1.ServerSocket1Accept(Sender: TObject;
  Socket: TCustomWinSocket);
begin
    StatusBar1.SimpleText := '连接成功';
    ListBox1.Items.Add( Socket.RemoteAddress );
end;

procedure TForm1.ServerSocket1ClientRead(Sender: TObject;
  Socket: TCustomWinSocket);
var
infoFromClient:String;
begin
    infoFromClient:=socket.ReceiveText;
    if( expect_no=system.Copy(infoFromClient,1,1) ) and (system.Copy(infoFromClient,2,1)<>'Y') then
        begin
                Memo1.Lines.Append('Packet'+system.Copy(infoFromClient,1,1)+' 正确接收');
                if (corrupt=false) and (loss=false) then
                begin
                        Memo1.Lines.Append('ACK'+system.Copy(infoFromClient,1,1)+' 正确发送');
                        ServerSocket1.Socket.Connections[0].SendText(system.Copy(infoFromClient,1,1)+'N');
                end
                else
                begin
                        if loss=true then
                        begin
                        Memo1.Lines.Append('ACK'+system.Copy(infoFromClient,1,1)+' 发送但丢失');
                        end;
                        if corrupt=true then
                        begin
                        Memo1.Lines.Append('ACK'+system.Copy(infoFromClient,1,1)+' 发送但被破坏');
                        ServerSocket1.Socket.Connections[0].SendText(system.Copy(infoFromClient,1,1)+'Y');
                        end;
                end;
                expect_no:=IntToStr((StrToInt(expect_no)+1)mod 10);
                Memo1.Lines.Append('期待 Packet'+expect_no);
        end
    else
    begin
        if( expect_no=system.Copy(infoFromClient,1,1) ) and (system.Copy(infoFromClient,2,1)='Y') then
                Memo1.Lines.Append('Packet'+system.Copy(infoFromClient,1,1)+'是期望的分组，但被破坏')
        else
                Memo1.Lines.Append('Packet'+system.Copy(infoFromClient,1,1)+'不是期望的分组,丢弃');
    end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
expect_no:='0';
corrupt:=false;
loss:=false;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
corrupt:=true;
loss:=false;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
loss:=true;
corrupt:=false;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
loss:=false;
corrupt:=false;
end;

end.