提交SocketV4 代理服务源码，欢迎补充SocketV5代码

[xlnrony]

unit Net.CrossSocket4Server;

interface

uses
Net.CrossSocket.Base, Net.CrossSocket, Net.CrossServer;

type
TCrossSocket4Connection = class(TCrossConnection, ICrossConnection)
private
FCurrentStep: Integer;
FOtherConnection: ICrossConnection;
public
constructor Create(AOwner: ICrossSocket; AClientSocket: THandle;
AConnectType: TConnectType); override;
end;

TCrossSocket4Server = class(TCrossServer)
protected
function CreateConnection(AOwner: ICrossSocket; AClientSocket: THandle;
AConnectType: TConnectType): ICrossConnection; override;
procedure LogicReceived(AConnection: ICrossConnection; ABuf: Pointer;
ALen: Integer); override;
end;

implementation

uses
Winapi.Windows, System.SysUtils;

{$POINTERMATH ON}
// +----+----+----+----+----+----+----+----+----+----+...+----+
// | VN | CD | DSTPORT |      DSTIP        | USERID      |NULL|
// +----+----+----+----+----+----+----+----+----+----+...+----+
// 1    1      2              4           variable       1
//
// VN      SOCKS协议版本号，应该是0x04
// CD      SOCKS命令，可取如下值:
// 0x01    CONNECT
// 0x02    BIND
// DSTPORT CD相关的端口信息
// DSTIP   CD相关的地址信息
// USERID  客户方的USERID
// NULL    0x00
//
// 响应报文格式如下:
//
// +----+----+----+----+----+----+----+----+
// | VN | CD | DSTPORT |      DSTIP        |
// +----+----+----+----+----+----+----+----+
// 1    1      2              4
//
// VN      应该为0x00而不是0x04
// CD      可取如下值:
// 0x5A    允许转发
// 0x5B    拒绝转发，一般性失败
// 0x5C    拒绝转发，SOCKS 4 Server无法连接到SOCS 4 Client所在主机的
// IDENT服务
// 0x5D    拒绝转发，请求报文中的USERID与IDENT服务返回值不相符
// DSTPORT CD相关的端口信息
// DSTIP   CD相关的地址信息

const
S4_VERSION = $04;
S4_CONNECT = $01;
S4_BIND = $02;

S4_CODE_5A = $5A;
S4_CODE_5B = $5B;
S4_CODE_5C = $5C;
S4_CODE_5D = $5D;

{ TCrossSocket4Server }

function TCrossSocket4Server.CreateConnection(AOwner: ICrossSocket;
AClientSocket: THandle; AConnectType: TConnectType): ICrossConnection;
begin
Result := TCrossSocket4Connection.Create(AOwner, AClientSocket, AConnectType);
end;

procedure TCrossSocket4Server.LogicReceived(AConnection: ICrossConnection;
ABuf: Pointer; ALen: Integer);
var
DstIP: array [0 .. 3] of Byte;
DstPort: array [0 .. 1] of Byte;
DstIPString: string;
DstPortWord: Word;
begin
try
with AConnection as TCrossSocket4Connection do
begin
case FCurrentStep of
1:
begin
if (PByte(ABuf)[0] <> S4_VERSION) or (PByte(ABuf)[1] = S4_BIND) then
begin
AConnection.Disconnect;
Exit;
end;

        if PByte(ABuf)[1] = S4_CONNECT then
        begin
          Move((PByte(ABuf) + 4)^, DstIP, 4);
          Move((PByte(ABuf) + 2)^, DstPort, 2);

          DstIPString := Format('%d.%d.%d.%d',
            [DstIP[0], DstIP[1], DstIP[2], DstIP[3]]);
          DstPortWord := (DstPort[0] shl 8) + DstPort[1];
          OutputDebugString(PChar('SockV4: Relay To ' + DstIPString + ':' +
            IntToStr(DstPortWord)));
          Connect(DstIPString, DstPortWord,
            procedure(Connection: ICrossConnection; Success: Boolean)
            var
              Buf8: array [0 .. 7] of Byte;
            begin
              FillChar(Buf8, 8, 0);

              if Success then
              begin
                (Connection as TCrossSocket4Connection).FOtherConnection :=
                  AConnection;
                FOtherConnection := Connection;

                (Connection as TCrossSocket4Connection).FCurrentStep := 2;
                FCurrentStep := 2;

                Buf8[1] := S4_CODE_5A;
              end
              else
              begin
                Buf8[1] := S4_CODE_5B;
              end;

              AConnection.SendBuf(@Buf8, 8);
            end);
        end;
      end;
    2:
      begin
        FOtherConnection.SendBuf(ABuf, ALen);
      end;
  end;
end;

except
on E: Exception do
begin
OutputDebugString(PChar('SockV4:' + E.Message));
AConnection.Disconnect;
end;
end;
end;

{ TCrossSocket4Connection }

constructor TCrossSocket4Connection.Create(AOwner: ICrossSocket;
AClientSocket: THandle; AConnectType: TConnectType);
begin
inherited;
FCurrentStep := 1;
end;

end.