截取指定程序的网络封包for delphi hook api

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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; 

uses 

SysUtils, 

windows, 

Messages, 

APIHook in ’APIHook.pas’; 

type 

PData = ^TData; 

TData = record 

Hook: THandle; 

Hooked: Boolean; 

end; 

var 

DLLData: 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; 

begin 

if not DLLData^.Hooked then 

begin 

HookAPI; 

DLLData^.Hooked := True; 

end; 

//调用下一个Hook 

CallNextHookEx(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; 

var 

ThreadID: LongWORD; 

begin 

Result := False; 

DLLData^.Hook := 0; 

ThreadID := GetWindowThreadProcessId(sWindow, nil); 

//给指定窗口挂上钩子 

DLLData^.Hook := SetWindowsHookEx(WH_GETMESSAGE, @HookProc, Hinstance, ThreadID); 

if DLLData^.Hook > 0 then 

Result := True //是否成功HOOK 

else 

exit; 

end; 

{------------------------------------} 

{过程名:UnHook 

{过程功能:卸载HOOK 

{过程参数:无 

{------------------------------------} 

procedure UnHook;stdcall; 

begin 

UnHookAPI; 

//卸载Hook 

UnhookWindowsHookEx(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); 

var 

FHandle: LongWORD; 

begin 

case Reason of 

DLL_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 then 

if GetLastError = ERROR_ALREADY_EXISTS then 

begin 

FHandle := OpenFileMapping(FILE_MAP_ALL_ACCESS, False, ’MYDLLDATA’); 

if FHandle = 0 then Exit; 

end else Exit; 

DLLData := MapViewOfFile(FHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0); 

if DLLData = nil then 

CloseHandle(FHandle); 

end; 

DLL_PROCESS_DETACH: 

begin 

if Assigned(DLLData) then 

begin 

UnmapViewOfFile(DLLData); 

DLLData := nil; 

end; 

end; 

end; 

end; 

{$R *.res} 

exports 

InstallHook, UnHook, HookProc; 

begin 

DLLProc := @MyDLLHandler; 

MyDLLhandler(DLL_PROCESS_ATTACH); 

DLLData^.Hooked := False; 

end. 

---------------------------------------------------------------------------------------- 

APIHook.Pas的代码: 

unit APIHook; 

interface 

uses 

SysUtils, 

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 record 

JmpCode: BYTE; 

Address: TSockProc; 

MovEAX: Array [0..2] of BYTE; 

end; 

//--------------------函数声明--------------------------- 

procedure HookAPI; 

procedure UnHookAPI; 

var 

OldSend, 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; 

var 

dwSize: 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; 

var 

dwSize: 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; 

var 

DLLModule: THandle; 

dwSize: cardinal; 

begin 

ProcessHandle := 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, dwSize); //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; 

var 

dwSize: Cardinal; 

begin 

WriteProcessMemory(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; 

interface 

uses 

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 

Dialogs, StdCtrls; 

type 

TForm1 = class(TForm) 

Button1: TButton; 

Button2: TButton; 

Edit1: TEdit; 

procedure Button1Click(Sender: TObject); 

procedure Button2Click(Sender: TObject); 

private 

{ Private declarations } 

public 

{ Public declarations } 

end; 

var 

Form1: TForm1; 

InstallHook: function (SWindow: THandle):Boolean;stdcall; 

UnHook: procedure;stdcall; 

implementation 

{$R *.dfm} 

procedure TForm1.Button1Click(Sender: TObject); 

var 

ModuleHandle: THandle; 

TmpWndHandle: THandle; 

begin 

TmpWndHandle := 0; 

TmpWndHandle := FindWindow(nil, ’目标窗口的标题’); 

if not isWindow(TmpWndHandle) then 

begin 

MessageBox(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’)) then 

ShowMessage(’Hook OK’); 

end; 

procedure TForm1.Button2Click(Sender: TObject); 

begin 

UnHook 

end; 

end.
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截取指定程序的网络封包for delphi hook api

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