//开启代理服务后… procedure TForm1.ServerSocket1Listen(Sender: TObject; Socket: TCustomWinSocket); begin Service_Enabled:=true; {置正在服务标志} N11.Enabled:=false; N21.Enabled:=true; end;//被代理端连接到代理服务器后,建立一个会话,并与套接字绑定… procedure TForm1.ServerSocket1ClientConnect(Sender: TObject; Socket: TCustomWinSocket); var i,j: integer; begin j:=-1; for i:=1 to sessions do {查找是否有空白项} if not session[i-1].Used and not session[i-1].CSocket.active then begin j:=i-1; {有,分配它} session[j].Used:=true; {置为在用} break; end else if not session[i-1].Used and session[i-1].CSocket.active then session[i-1].CSocket.active:=false; if j=-1 then begin {无,新增一个} j:=sessions; inc(sessions); setlength(session,sessions); session[j].Used:=true; {置为在用} session[j].CSocket:=TClientSocket.Create(nil); session[j].CSocket.OnConnect:=ClientSocket1Connect; session[j].CSocket.OnDisconnect:=ClientSocket1Disconnect; session[j].CSocket.OnError:=ClientSocket1Error; session[j].CSocket.OnRead:=ClientSocket1Read; session[j].CSocket.OnWrite:=ClientSocket1Write; session[j].Lookingup:=false; end; session[j].SS_Handle:=socket.socketHandle; {保存句柄,实现绑定} session[j].Request:=false; {无请求} session[j].client_connected:=true; {客户机已连接} session[j].remote_connected:=false; {远程未连接} edit1.text:=inttostr(sessions); end;//被代理端断开时… procedure TForm1.ServerSocket1ClientDisconnect(Sender: TObject; Socket: TCustomWinSocket); var i,j,k: integer; begin for i:=1 to sessions do if (session[i-1].SS_Handle=socket.SocketHandle) and session[i-1].Used then begin session[i-1].client_connected:=false; {客户机未连接} if session[i-1].remote_connected then session[i-1].CSocket.active:=false {假如远程尚连接,断开它} else session[i-1].Used:=false; {假如两者都断开,则置释放资源标志} break; end; j:=sessions; k:=0; for i:=1 to j do {统计会话数组尾部有几个未用项} begin if session[j-i].Used then break; inc(k); end; if k>0 then {修正会话数组,释放尾部未用项} begin sessions:=sessions-k; setlength(session,sessions); end; edit1.text:=inttostr(sessions); end;//通信错误出现时… procedure TForm1.ServerSocket1ClientError(Sender: TObject; Socket: TCustomWinSocket; ErrorEvent: TErrorEvent; var ErrorCode: Integer); var i,j,k: integer; begin for i:=1 to sessions do if (session[i-1].SS_Handle=socket.SocketHandle) and session[i-1].Used then begin session[i-1].client_connected:=false; {客户机未连接} if session[i-1].remote_connected then session[i-1].CSocket.active:=false {假如远程尚连接,断开它} else session[i-1].Used:=false; {假如两者都断开,则置释放资源标志} break; end; j:=sessions; k:=0; for i:=1 to j do begin if session[j-i].Used then break; inc(k); end; if k>0 then begin sessions:=sessions-k; setlength(session,sessions); end; edit1.text:=inttostr(sessions); errorcode:=0; end;//被代理端发送来页面请求时… procedure TForm1.ServerSocket1ClientRead(Sender: TObject; Socket: TCustomWinSocket); var tmp,line,host: string; i,j,port: integer; begin for i:=1 to sessions do {判断是哪一个会话} if session[i-1].Used and (session[i-1].SS_Handle=socket.sockethandle) then begin session[i-1].request_str:=socket.ReceiveText; {保存请求数据} tmp:=session[i-1].request_str; {存放到临时变量} memo1.lines.add(tmp); j:=pos(char(13)+char(10),tmp); {一行标志} while j>0 do {逐行扫描请求文本,查找主机地址} begin line:=copy(tmp,1,j-1); {取一行} delete(tmp,1,j+1); {删除一行} j:=pos('Host',line); {主机地址标志} if j>0 then begin delete(line,1,j+5); {删除前面的无效字符} j:=pos(':',line); if j>0 then begin host:=copy(line,1,j-1); delete(line,1,j); try port:=strtoint(line); except port:=80; end; end else begin host:=trim(line); {获取主机地址} port:=80; end; if not session[i-1].remote_connected then {假如远征尚未连接} begin session[i-1].Request:=true; {置请求数据就绪标志} session[i-1].CSocket.host:=host; {设置远程主机地址} session[i-1].CSocket.port:=port; {设置端口} session[i-1].CSocket.active:=true; {连接远程主机} session[i-1].Lookingup:=true; {置标志} session[i-1].LookupTime:=0; {从0开始计时} end else {假如远程已连接,直接发送请求} session[i-1].CSocket.socket.sendtext(session[i-1].request_str); break; {停止扫描请求文本} end; j:=pos(char(13)+char(10),tmp); {指向下一行} end; break; {停止循环} end; end;
用Delphi设计自己的代理服务器 笔者在编写一个上网计费软件时,涉及到如何对局域网中各工作站上网计费问题。一般来讲,这些工作站通过代理服务器上网,而采用现成的代理服务器软件时,由于代理服务器软件是封闭的系统,很难编写程序获取实时的上网计时信息。因此,考虑是否能编写自己的代理服务器,一方面解决群体上网,另一方面又解决上网的计费问题呢?
经过实验性编程,终于圆满地解决了该问题。现写出来,与各位同行分享。思路
当前流行的浏览器的系统选项中有一个参数,即“通过代理服务器连接”,经过编程测
试,当局域网中一台工作站指定了该属性,再发出Internet请求时,请求数据将发送到所指定的代理服务器上,以下为请求数据包示例:
GET http://home.microsoft.com/intl/cn/ HTTP/1.0
Accept: */*
Accept-Language: zh-cn
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 5.0; Windows NT)
Host: home.microsoft.com
Proxy-Connection: Keep-Alive
其中第一行为目标URL及相关方法、协议,“Host”行指定了目标主机的地址。
由此知道了代理服务的过程:接收被代理端的请求、连接真正的主机、接收主机返回的数据、将接收数据发送到被代理端。
为此可编写一个简单的程序,完成上述网络通信重定向问题。
用Delphi设计时,选用ServerSocket作为与被代理工作站通信的套接字控件,选用ClientSocket动态数组作为与远程主机通信的套接字控件。
编程时应解决的一个重要问题是多重连接处理问题,为了加快代理服务的速度和被代理端的响应速度,套接字控件的属性应设为非阻塞型;各通信会话与套接字动态绑定,用套接字的SocketHandle属性值确定属于哪一个会话。
通信的衔接过程如下图所示: 代理服务器
Serversocket
(1) 接 收
被代理端 发 送 远程主机
(6) (2) (5)
Browser ClientSocket (4) Web Server
接 收
发 送 (3)
(1)、被代理端浏览器发出Web请求,代理服务器的Serversocket接收到请求。
(2)、代理服务器程序自动创建一个ClientSocket,并设置主机地址、端口等属性,然后连接远程主机。
(3)、远程连通后激发发送事件,将Serversocket接收到的Web请求数据包发送到远程主机。
(4)、当远程主机返回页面数据时,激发ClientSocket的读事件,读取页面数据。
(5)、代理服务器程序根据绑定信息确定属于ServerSocket控件中的哪一个Socket应该将从主机接收的页面信息发送到被代理端。
(6)、ServerSocket中的对应Socket将页面数据发送到被代理端。程序编写
使用Delphi设计以上通信过程非常简单,主要是ServerSocket、ClientSocket的相关事
件驱动程序的程序编写。下面给出作者编写的实验用代理服务器界面与源程序清单,内含简要功能说明:unit main;interfaceuses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, ScktComp, TrayIcon, Menus, StdCtrls;type
session_record=record
Used: boolean; {会话记录是否可用}
SS_Handle: integer; {代理服务器套接字句柄}
CSocket: TClientSocket; {用于连接远程的套接字}
Lookingup: boolean; {是否正在查找服务器}
LookupTime: integer; {查找服务器时间}
Request: boolean; {是否有请求}
request_str: string; {请求数据块}
client_connected: boolean; {客户机联机标志}
remote_connected: boolean; {远程服务器连接标志}
end;type
TForm1 = class(TForm)
ServerSocket1: TServerSocket;
ClientSocket1: TClientSocket;
Timer2: TTimer;
TrayIcon1: TTrayIcon;
PopupMenu1: TPopupMenu;
N11: TMenuItem;
N21: TMenuItem;
N1: TMenuItem;
N01: TMenuItem;
Memo1: TMemo;
Edit1: TEdit;
Label1: TLabel;
Timer1: TTimer;
procedure Timer2Timer(Sender: TObject);
procedure N11Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure N21Click(Sender: TObject);
procedure N01Click(Sender: TObject);
procedure ServerSocket1ClientConnect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocket1ClientDisconnect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocket1ClientError(Sender: TObject;
Socket: TCustomWinSocket; ErrorEvent: TErrorEvent;
var ErrorCode: Integer);
procedure ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
procedure ClientSocket1Connect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ClientSocket1Disconnect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ClientSocket1Error(Sender: TObject; Socket: TCustomWinSocket;
ErrorEvent: TErrorEvent; var ErrorCode: Integer);
procedure ClientSocket1Write(Sender: TObject;
Socket: TCustomWinSocket);
procedure ClientSocket1Read(Sender: TObject; Socket: TCustomWinSocket);
procedure ServerSocket1Listen(Sender: TObject;
Socket: TCustomWinSocket);
procedure AppException(Sender: TObject; E: Exception);
procedure Timer1Timer(Sender: TObject);
private
{ Private declarations }
public
Service_Enabled: boolean; {代理服务是否开启}
session: array of session_record; {会话数组}
sessions: integer; {会话数}
LookUpTimeOut: integer; {连接超时值}
InvalidRequests: integer; {无效请求数}
end;var
Form1: TForm1;implementation{$R *.DFM}//系统启动定时器,启动窗显示完成后,缩小到System Tray…
procedure TForm1.Timer2Timer(Sender: TObject);
begin
timer2.Enabled:=false; {关闭定时器}
sessions:=0; {会话数=0}
Application.OnException := AppException; {为了屏蔽代理服务器出现的异常}
invalidRequests:=0; {0错误}
LookUpTimeOut:=60000; {超时值=1分钟}
timer1.Enabled:=true; {打开定时器}
n11.Enabled:=false; {开启服务菜单项失效}
n21.Enabled:=true; {关闭服务菜单项有效}
serversocket1.Port:=988; {代理服务器端口=988}
serversocket1.Active:=true; {开启服务}
form1.hide; {隐藏界面,缩小到System Tray上}
end;//开启服务菜单项…
procedure TForm1.N11Click(Sender: TObject);
begin
serversocket1.Active:=true; {开启服务}
end;
//停止服务菜单项…
procedure TForm1.N21Click(Sender: TObject);
begin
serversocket1.Active:=false; {停止服务}
N11.Enabled:=True;
N21.Enabled:=False;
Service_Enabled:=false; {标志清零}
end;
//主窗口建立…
procedure TForm1.FormCreate(Sender: TObject);
begin
Service_Enabled:=false;
timer2.Enabled:=true; {窗口建立时,打开定时器}
end;//窗口关闭时…
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
timer1.Enabled:=false; {关闭定时器}
if Service_Enabled then
serversocket1.Active:=false; {退出程序时关闭服务}
end;//退出程序按钮…
procedure TForm1.N01Click(Sender: TObject);
begin
form1.Close; {退出程序}
end;
procedure TForm1.ServerSocket1Listen(Sender: TObject;
Socket: TCustomWinSocket);
begin
Service_Enabled:=true; {置正在服务标志}
N11.Enabled:=false;
N21.Enabled:=true;
end;//被代理端连接到代理服务器后,建立一个会话,并与套接字绑定…
procedure TForm1.ServerSocket1ClientConnect(Sender: TObject;
Socket: TCustomWinSocket);
var
i,j: integer;
begin
j:=-1;
for i:=1 to sessions do {查找是否有空白项}
if not session[i-1].Used and not session[i-1].CSocket.active then
begin
j:=i-1; {有,分配它}
session[j].Used:=true; {置为在用}
break;
end
else
if not session[i-1].Used and session[i-1].CSocket.active then
session[i-1].CSocket.active:=false;
if j=-1 then
begin {无,新增一个}
j:=sessions;
inc(sessions);
setlength(session,sessions);
session[j].Used:=true; {置为在用}
session[j].CSocket:=TClientSocket.Create(nil);
session[j].CSocket.OnConnect:=ClientSocket1Connect;
session[j].CSocket.OnDisconnect:=ClientSocket1Disconnect;
session[j].CSocket.OnError:=ClientSocket1Error;
session[j].CSocket.OnRead:=ClientSocket1Read;
session[j].CSocket.OnWrite:=ClientSocket1Write;
session[j].Lookingup:=false;
end;
session[j].SS_Handle:=socket.socketHandle; {保存句柄,实现绑定}
session[j].Request:=false; {无请求}
session[j].client_connected:=true; {客户机已连接}
session[j].remote_connected:=false; {远程未连接}
edit1.text:=inttostr(sessions);
end;//被代理端断开时…
procedure TForm1.ServerSocket1ClientDisconnect(Sender: TObject;
Socket: TCustomWinSocket);
var
i,j,k: integer;
begin
for i:=1 to sessions do
if (session[i-1].SS_Handle=socket.SocketHandle) and session[i-1].Used then
begin
session[i-1].client_connected:=false; {客户机未连接}
if session[i-1].remote_connected then
session[i-1].CSocket.active:=false {假如远程尚连接,断开它}
else
session[i-1].Used:=false; {假如两者都断开,则置释放资源标志}
break;
end;
j:=sessions;
k:=0;
for i:=1 to j do {统计会话数组尾部有几个未用项}
begin
if session[j-i].Used then
break;
inc(k);
end;
if k>0 then {修正会话数组,释放尾部未用项}
begin
sessions:=sessions-k;
setlength(session,sessions);
end;
edit1.text:=inttostr(sessions);
end;//通信错误出现时…
procedure TForm1.ServerSocket1ClientError(Sender: TObject;
Socket: TCustomWinSocket; ErrorEvent: TErrorEvent;
var ErrorCode: Integer);
var
i,j,k: integer;
begin
for i:=1 to sessions do
if (session[i-1].SS_Handle=socket.SocketHandle) and session[i-1].Used then
begin
session[i-1].client_connected:=false; {客户机未连接}
if session[i-1].remote_connected then
session[i-1].CSocket.active:=false {假如远程尚连接,断开它}
else
session[i-1].Used:=false; {假如两者都断开,则置释放资源标志}
break;
end;
j:=sessions;
k:=0;
for i:=1 to j do
begin
if session[j-i].Used then
break;
inc(k);
end;
if k>0 then
begin
sessions:=sessions-k;
setlength(session,sessions);
end;
edit1.text:=inttostr(sessions);
errorcode:=0;
end;//被代理端发送来页面请求时…
procedure TForm1.ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
var
tmp,line,host: string;
i,j,port: integer;
begin
for i:=1 to sessions do {判断是哪一个会话}
if session[i-1].Used and (session[i-1].SS_Handle=socket.sockethandle) then
begin
session[i-1].request_str:=socket.ReceiveText; {保存请求数据}
tmp:=session[i-1].request_str; {存放到临时变量}
memo1.lines.add(tmp);
j:=pos(char(13)+char(10),tmp); {一行标志}
while j>0 do {逐行扫描请求文本,查找主机地址}
begin
line:=copy(tmp,1,j-1); {取一行}
delete(tmp,1,j+1); {删除一行}
j:=pos('Host',line); {主机地址标志}
if j>0 then
begin
delete(line,1,j+5); {删除前面的无效字符}
j:=pos(':',line);
if j>0 then
begin
host:=copy(line,1,j-1);
delete(line,1,j);
try
port:=strtoint(line);
except
port:=80;
end;
end
else
begin
host:=trim(line); {获取主机地址}
port:=80;
end;
if not session[i-1].remote_connected then {假如远征尚未连接}
begin
session[i-1].Request:=true; {置请求数据就绪标志}
session[i-1].CSocket.host:=host; {设置远程主机地址}
session[i-1].CSocket.port:=port; {设置端口}
session[i-1].CSocket.active:=true; {连接远程主机}
session[i-1].Lookingup:=true; {置标志}
session[i-1].LookupTime:=0; {从0开始计时}
end
else
{假如远程已连接,直接发送请求}
session[i-1].CSocket.socket.sendtext(session[i-1].request_str);
break; {停止扫描请求文本}
end;
j:=pos(char(13)+char(10),tmp); {指向下一行}
end;
break; {停止循环}
end;
end;