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我想编写一个“中间人”程序来帮助我调试我正在开发的网络应用程序。经过一番谷歌搜索（我根本不知道该怎么做），我想到了我必须创建一个钩子（我以前用其他语言使用过钩子，但它们要简单得多）来拦截 WinSock 的send. 根据各种文章，我必须修改函数的前5个字节才能跳转到我的函数，做一些工作，然后跳转回来。我在网上找到了这段代码，我在控制台应用程序中重写了它。这是我想出的：

#include "stdafx.h"
#include <iostream>
#include <WinSock2.h>
#include <windows.h>

#pragma comment(lib, "ws2_32.lib")
#define JMP(frm, to) (int)(((int)to - (int)frm) - 5);

#define DEF_PORT 27015

using namespace std;

bool HookSend();
void UnhookSend();

DWORD SendOriginal          = 0;
DWORD SendReturn            = 0;
DWORD *SendHookFunc         = 0;
DWORD OldProtection         = 0;

char* send_buffer;
int send_sizeofdata         = 0;
SOCKET send_s;
int send_flags              = 0;

HINSTANCE hWinSock          = 0;

void __declspec(naked) __stdcall SendHook()
{
    __asm
    { 
        mov     edi,edi
        push    ebp
        mov     ebp, esp
        mov     eax, [ebp+0x08]         /* Param 1 : Socket */
        mov     send_s, eax
        mov     eax, [ebp+0x0C]         /* Param 2 : buffer */
        mov     [send_buffer], eax
        mov     eax, [ebp+0x10]         /*Param 3 : Size*/
        mov     send_sizeofdata, eax
        mov     eax, [ebp+0x14]         /*Param 4 : flags*/
        mov     send_flags, eax
        jmp     SendReturn
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    WSADATA wsaData;
    SOCKET soket;
    sockaddr_in soketDesc;

    char buf[256];

    cout << "Packet Reader by Timothy Volpe" << endl;
    cout << "Program will read packets sent" << endl << endl;

    cout << "Loading WinSock" << endl;
    if((hWinSock = LoadLibrary("ws2_32.dll")) == NULL)
    {
        cout << "Failed to load WinSock library" << endl;
        return -1;
    }

    cout << "Starting WinSock API" << endl;

    if(WSAStartup(MAKEWORD(2,2), &wsaData) != NO_ERROR)
    {
        cout << "Failed to load WinSock API (Error:" << WSAGetLastError() << ")" << endl;
        cout << "Press enter to exit" << endl;
        cin.get();
        return -1;
    }

    cout << "Hooking send()" << endl;
    if(!HookSend())
    {
        cout << "Press enter to exit" << endl;
        cin.get();
        return -1;
    }
    cout << "Hooked successfully!" << endl;

    cout << "Creating socket" << endl;
    soket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if(soket == INVALID_SOCKET)
    {
        cout << "Failed to create socket (Error:" << WSAGetLastError() << ")" << endl;
        UnhookSend();
        cout << "Press enter to exit" << endl;
        cin.get();
        return -1;
    }

    cout << "Connecting socket to port " << DEF_PORT << endl;
    soketDesc.sin_family        = AF_INET;
    soketDesc.sin_addr.s_addr   = inet_addr("127.0.0.1");
    soketDesc.sin_port          = htons(DEF_PORT);
    if(connect(soket, (SOCKADDR*)&soketDesc, sizeof(soketDesc)) == SOCKET_ERROR)
    {
        cout << "Failed to connect socket (Error:" << WSAGetLastError() << ")" << endl;
        UnhookSend();
        cout << "Press enter to exit" << endl;
        cin.get();
        return -1;
    }

    cout << "Enter some data to send (MAX 256):" << endl;
    cin.get(buf, 256); //Read 256 chars
    cout << "Sending \"" << buf << "\"" << endl;

    //Send the data
    send(soket, buf, (int)sizeof(buf), 0);

    //Close
    closesocket(soket);
    WSACleanup();

    UnhookSend();

    cout << endl << "Press enter to exit" << endl;
    cin.clear();
    cin.ignore();
    cin.get();

    return 0;
}

bool HookSend()
{
    //Get the new function's address
    SendHookFunc = (DWORD*)SendHook;
    //Get the send() function's address
    SendOriginal = (DWORD)GetProcAddress(hWinSock, "send");
    //Get the return address, which is 5 bytes past the start
    SendReturn = SendOriginal + 5;
    printf("SEND\tStart: %x\t Return: %x\n", SendOriginal, SendReturn);
    //Change protection for the first 5 bytes
    VirtualProtect((void*)SendOriginal, 0x05, PAGE_READWRITE, &OldProtection);
    *(BYTE*)(SendOriginal) = 0xe9;
    *(int*)(SendOriginal+1) = JMP(SendOriginal, SendHookFunc);

    return true;
}

void UnhookSend()
{
    cout << "Unhooking..." << endl;
    //Restore the old stuff
    *(WORD*)SendOriginal = 0xFF8B;
    *(BYTE*)(SendOriginal+1) = 0x55;
    *(WORD*)(SendOriginal+3) = 0xEC8B;
    //Restore protection
    VirtualProtect((void*)SendOriginal, 0x05, OldProtection, &OldProtection);
}

但是，它不起作用，因为我在socket(). HookSend如果我删除对and的调用UnhookSend，它运行良好。如果我改变调用的顺序（例如放在WSAStartupafter HookSend），它会在第一个 WinSock 函数上崩溃。所以我想我喜欢破坏整个图书馆什么的，我真的不太确定。老实说，我今天刚学了汇编（嗯，Visual Studio 的版本）。这很容易掌握，我相信我理解这段代码中的程序集。我的代码与网络上的代码几乎相同，所以我不知道出了什么问题。我想知道这是操作系统冲突，还是项目设置问题，还是完全不同的事情。

我在这里不知所措，所以任何指向正确方向的指针都会很棒！另外，如果我完全错了（比如有更好的方法），请随时告诉我。而且我确实知道Microsoft 的 Detours，但我宁愿不将它用于这么简单的事情（而且我也不喜欢在我脑海中挥之不去的非商业用途许可证的想法，即使这可能永远不会被释放）。

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2 回答 2

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It is rarely necessary to debug the actual API calls themselves in such a brute-force manner. You could just use a packet sniffer like Wireshark to capture and analyze the network traffic that is being transmitted. But if you must debug the API calls, you are essentially trying to manually implement a Detour, so you really should use Microsoft's Detours library to implement a real Detour correctly. A better option is to use WinSock's built-in debugging functionality and not hook the API functions at all. Let the OS handle the hooking and logging of calls and parameters for you.

于 2012-06-18T02:40:45.907 回答
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您没有检查对 VirtualProtect 的调用的返回值；我的猜测是它没有成功，你可能没有必要的权利。您是否以“管理员”身份运行此代码并且您是否禁用了 Windows UAC 的东西？

更新您的代码以检查 VirtualProtect 的返回值，并让我们知道这是否揭示了任何内容。

于 2012-06-18T01:59:49.247 回答