Delphi拦截网络数据封包

有时候我们需要对其它应用程序发送和接收的网络数据进行拦截,比如要对IE发送的HTTP头进行分析,得到请求的地址等.这次我们可以用一些例如WPE, Sniffer之类的工具来达到目的.但是工具功能有限,要想实现更强大的功能,还是我们自己动手来DIY吧.拦截网络数据封包的方法有三种,一是将网卡设为混杂模式,这次就可以监视到局域网上所有的数据包,二是HOOK目标进程的发送和接收的API函数,第三种方法是自己实现一个代理的DLL.在这里我们使用HOOK API的方法,这样易于实现,而且也不会得到大量的无用数据(如第一种方法就会监视到所有的网络数据).下面是一个尽量简化了的API HOOK的模版,原理是利用消息钩子将DLL中的代码注入到目标进程中,再用GetProcAddress得到API函数入口地址,将函数入口址改为自己定义的函数入口,这样就得到了API函数的相应参数,处理完后,再改回真实API函数入口地址,并调用它.HOOK.DLL的代码:library Hook;usesSysUtils,windows,Messages,APIHook in 'APIHook.pas';typePData = ^TData;TData = recordHook: THandle;Hooked: Boolean;end;varDLLData: PData;{------------------------------------}{过程名:HookProc{过程功能:HOOK过程{过程参数:nCode, wParam, lParam消息的相{ 关参数{------------------------------------}procedure HookProc(nCode, wParam, lParam: LongWORD);stdcall; beginif not DLLData^.Hooked thenbeginHookAPI;DLLData^.Hooked := True;end;//调用下一个HookCallNextHookEx(DLLData^.Hook, nCode, wParam, lParam); end;{------------------------------------}{函数名:InstallHook{函数功能:在指定窗口上安装HOOK{函数参数:sWindow:要安装HOOK的窗口{返回值:成功返回TRUE,失败返回FALSE{------------------------------------}function InstallHook(SWindow: LongWORD):Boolean;stdcall;varThreadID: LongWORD;Result := False;DLLData^.Hook := 0;ThreadID := GetWindowThreadProcessId(sWindow, nil);//给指定窗口挂上钩子DLLData^.Hook := SetWindowsHookEx(WH_GETMESSAGE, @HookProc, H instance, ThreadID);if DLLData^.Hook > 0 thenResult := True //是否成功HOOKelseexit;end;{------------------------------------}{过程名:UnHook{过程功能:卸载HOOK{过程参数:无{------------------------------------}procedure UnHook;stdcall;beginUnHookAPI;//卸载HookUnhookWindowsHookEx(DLLData^.Hook);end;{------------------------------------}{过程名:DLL入口函数{过程功能:进行DLL初始化,释放等{过程参数:DLL状态{------------------------------------}procedure MyDLLHandler(Reason: Integer);FHandle: LongWORD;begincase Reason ofDLL_PROCESS_ATTACH:begin //建立文件映射,以实现DLL中的全局变量FHandle := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, $ffff, 'MYDLLDATA');if FHandle = 0 thenif GetLastError = ERROR_ALREADY_EXISTS thenbeginFHandle := OpenFileMapping(FILE_MAP_ALL_ACCESS, False, 'MYDLLD ATA');if FHandle = 0 then Exit;end else Exit;DLLData := MapViewOfFile(FHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0);if DLLData = nil thenCloseHandle(FHandle);end;DLL_PROCESS_DETACH:beginif Assigned(DLLData) thenbeginUnmapViewOfFile(DLLData);DLLData := nil;end;end;end;end;{$R *.res}exportsInstallHook, UnHook, HookProc;beginDLLProc := @MyDLLHandler;MyDLLhandler(DLL_PROCESS_ATTACH);DLLData^.Hooked := False;end.----------------------------------------------------------------------------------------APIHook.Pas的代码:unit APIHook;interfaceusesSysUtils,Windows, WinSock;type//要HOOK的API函数定义TSockProc = function (s: TSocket; var Buf; len, flags: Integer): Integer; stdcall;PJmpCode = ^TJmpCode;TJmpCode = packed recordJmpCode: BYTE;Address: TSockProc;MovEAX: Array [0..2] of BYTE;end;//--------------------函数声明---------------------------procedure HookAPI;procedure UnHookAPI;varOldSend, OldRecv: TSockProc; //原来的API地址JmpCode: TJmpCode;OldProc: array [0..1] of TJmpCode;AddSend, AddRecv: pointer; //API地址TmpJmp: TJmpCode;ProcessHandle: THandle;implementation{---------------------------------------}{函数功能:Send函数的HOOK{函数参数:同Send{函数返回值:integer{---------------------------------------}function MySend(s: TSocket; var Buf; len, flags: Integer): Integer; stdcall; vardwSize: cardinal;begin//这儿进行发送的数据处理MessageBeep(1000); //简单的响一声//调用直正的Send函数WriteProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8, dwSize); Result := OldSend(S, Buf, len, flags);JmpCode.Address := @MySend;WriteProcessMemory(ProcessHandle, AddSend, @JmpCode, 8, dwSize); end;{---------------------------------------}{函数功能:Recv函数的HOOK{函数参数:同Recv{函数返回值:integer{---------------------------------------}function MyRecv(s: TSocket; var Buf; len, flags: Integer): Integer; stdcall; vardwSize: cardinal;begin//这儿进行接收的数据处理MessageBeep(1000); //简单的响一声//调用直正的Recv函数WriteProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8, dwSize); Result := OldRecv(S, Buf, len, flags);JmpCode.Address := @MyRecv;WriteProcessMemory(ProcessHandle, AddRecv, @JmpCode, 8, dwSize); end;{------------------------------------}{过程功能:HookAPI{过程参数:无{------------------------------------}procedure HookAPI;varDLLModule: THandle;dwSize: cardinal;beginProcessHandle := GetCurrentProcess;DLLModule := LoadLibrary('ws2_32.dll');AddSend := GetProcAddress(DLLModule, 'send'); //取得API地址AddRecv := GetProcAddress(DLLModule, 'recv');JmpCode.JmpCode := $B8;JmpCode.MovEAX[0] := $FF;JmpCode.MovEAX[1] := $E0;JmpCode.MovEAX[2] := 0;ReadProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8, dwSize); JmpCode.Address := @MySend;WriteProcessMemory(ProcessHandle, AddSend, @JmpCode, 8, dwSiz e); //修改Send入口ReadProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8, dwSize); JmpCode.Address := @MyRecv;WriteProcessMemory(ProcessHandle, AddRecv, @JmpCode, 8, dwSize); //修改Recv入口OldSend := AddSend;OldRecv := AddRecv;end;{------------------------------------}{过程功能:取消HOOKAPI{过程参数:无{------------------------------------}procedure UnHookAPI;vardwSize: Cardinal;beginWriteProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8, dwSize); WriteProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8, dwSize); end;end.---------------------------------------------------------------------------------------------编译这个DLL后,再新建一个程序调用这个DLL的InstallHook并传入目标进程的主窗口句柄就可:unit fmMain;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Form s,Dialogs, StdCtrls;typeTForm1 = class(TForm)Button1: TButton;Button2: TButton;Edit1: TEdit;procedure Button1Click(Sender: TObject);procedure Button2Click(Sender: TObject);private{ Private declarations }public{ Public declarations }end;varForm1: TForm1;InstallHook: function (SWindow: THandle):Boolean;stdcall;UnHook: procedure;stdcall;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);varModuleHandle: THandle;TmpWndHandle: THandle;beginTmpWndHandle := 0;TmpWndHandle := FindWindow(nil, '目标窗口的标题');if not isWindow(TmpWndHandle) thenbeginMessageBox(self.Handle, '没有找到窗口', '!!!', MB_OK);exit;end;ModuleHandle := LoadLibrary('Hook.dll');@InstallHook := GetProcAddress(ModuleHandle, 'InstallHook');@UnHook := GetProcAddress(ModuleHandle, 'UnHook');if InstallHook(FindWindow(nil, 'Untitled')) thenShowMessage('Hook OK');end;procedure TForm1.Button2Click(Sender: TObject);beginUnHookend;这段代码讲解；找到winsock 中send和Recv 地址来回替换，send和recv是封包发送，接受的函数，其中参数，buf为其中的数据封包，就是本段程序要的，自己定义m yseng和myrecv来替换。