用delphi设计代理服务器.txt

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  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;

file://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;

file://当连接远程主机成功时…
procedure TForm1.ClientSocket1Connect(Sender: TObject;
  Socket: TCustomWinSocket);
var
i: integer;
begin
   for i:=1 to sessions do
      if (session[i-1].CSocket.socket.sockethandle=socket.SocketHandle) and session[i-1].Used then
         begin
            session[i-1].CSocket.tag:=socket.SocketHandle;
            session[i-1].remote_connected:=true;   {置远程主机已连通标志}
            session[i-1].Lookingup:=false;         {清标志}
            break;
         end;
end;


file://当远程主机断开时…
procedure TForm1.ClientSocket1Disconnect(Sender: TObject;
  Socket: TCustomWinSocket);
var
i,j,k: integer;
begin
   for i:=1 to sessions do
      if (session[i-1].CSocket.tag=socket.SocketHandle) and session[i-1].Used then
         begin
            session[i-1].remote_connected:=false;       {置为未连接}
            if not session[i-1].client_connected then
               session[i-1].Used:=false       {假如客户机已断开，则置释放资源标志}
            else
               for k:=1 to serversocket1.Socket.ActiveConnections do
                  if (serversocket1.Socket.Connections[k-1].SocketHandle=session[i-1].SS_Handle) and session[i-1].used then
                     begin
                        serversocket1.Socket.Connections[k-1].Close;
                        break;
                     end;
            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                        {修正会话数组}
      begin
         sessions:=sessions-k;
         setlength(session,sessions);
      end;
   edit1.text:=inttostr(sessions);
end;

file://当与远程主机通信发生错误时…
procedure TForm1.ClientSocket1Error(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].CSocket.tag=socket.SocketHandle) and session[i-1].Used then
         begin
            socket.close;
            session[i-1].remote_connected:=false;       {置为未连接}
            if not session[i-1].client_connected then
               session[i-1].Used:=false        {假如客户机已断开，则置释放资源标志}
            else
               for k:=1 to serversocket1.Socket.ActiveConnections do
                  if (serversocket1.Socket.Connections[k-1].SocketHandle=session[i-1].SS_Handle) and session[i-1].used then
                     begin
                        serversocket1.Socket.Connections[k-1].Close;
                        break;
                     end;
            break;
         end;
   j:=sessions;
   k:=0;
   for i:=1 to j do
      begin
         if session[j-i].Used then
            break;
         inc(k);
      end;
   errorcode:=0;
   if k>0 then                        {修正会话数组}
      begin
         sessions:=sessions-k;
         setlength(session,sessions);
      end;
   edit1.text:=inttostr(sessions);
end;

file://向远程主机发送页面请求…
procedure TForm1.ClientSocket1Write(Sender: TObject;
  Socket: TCustomWinSocket);
var
i: integer;
begin
   for i:=1 to sessions do
      if (session[i-1].CSocket.tag=socket.SocketHandle) and session[i-1].Used then
         begin
            if session[i-1].Request then
               begin
                  socket.SendText(session[i-1].request_str);   {假如有请求，发送}
                  session[i-1].Request:=false;                 {清标志}
               end;
            break;
         end;
end;

file://远程主机发来页面数据时…
procedure TForm1.ClientSocket1Read(Sender: TObject;
  Socket: TCustomWinSocket);
var
i,j: integer;
rec_bytes: integer;                  {传回的数据块长度}
rec_Buffer: array[0..2047] of char;  {传回的数据块缓冲区}
begin
   for i:=1 to sessions do
      if (session[i-1].CSocket.tag=socket.SocketHandle) and session[i-1].Used then
         begin
            rec_bytes:=socket.ReceiveBuf(rec_buffer,2048);    {接收数据}
            for j:=1 to serversocket1.Socket.ActiveConnections do
               if serversocket1.Socket.Connections[j-1].SocketHandle=session[i-1].SS_Handle then
                  begin
                     serversocket1.Socket.Connections[j-1].SendBuf(rec_buffer,rec_bytes);  {发送数据}
                     break;
                  end;
            break;
         end;
end;

file://“页面找不到”等错误信息出现时…
procedure TForm1.AppException(Sender: TObject; E: Exception);
begin
  inc(invalidrequests);
end;

file://查找远程主机定时…
procedure TForm1.Timer1Timer(Sender: TObject);
var
i,j: integer;
begin
   for i:=1 to sessions do
      if session[i-1].Used and session[i-1].Lookingup then    {假如正在连接}
         begin
            inc(session[i-1].LookupTime);
            if session[i-1].LookupTime>lookuptimeout then     {假如超时}
               begin
                  session[i-1].Lookingup:=false;
                  session[i-1].CSocket.active:=false;         {停止查找}
                  for j:=1 to serversocket1.Socket.ActiveConnections do
                     if serversocket1.Socket.Connections[j-1].SocketHandle=session[i-1].SS_Handle then
                        begin
                           serversocket1.Socket.Connections[j-1].Close;  {断开客户机}
                           break;
                        end;
               end;
         end;
end;
end.

3、 后记
由于这种设计思路仅仅在被代理端和远程主机之间增加了一个重定向功能，被代理端原
有的缓存技术等特点均保留，因此效率较高。经过测试，利用1个33.6K的Modem上网时，三到十个被代理工作站同时上网，仍有较好的响应速度。由于被代理工作站和代理服务器工作站之间的连接一般通过高速链路，因此瓶颈主要出现在代理服务器的上网方式上。
通过上述方法，作者成功开发了一套完善的代理服务器软件并与机房计费系统完全集
成，实现了利用一台工作站完成上网代理、上网计费、用机计费等功能。 有编程经验的朋友完全可以另行增加代理服务器功能，如设定禁止访问站点、统计客户流量、Web访问列表等等。