Is it possible to subclass a web browser using winapi c++?

Question

The main goal is to block maximalize web browser window using subclassing and dll.

I have 2 apps: injector and the dll.

In injector app I load that dll, find window by title, get functions from dll and execute that functions ( their names are hook and unhook ) from dll. So this is standard injector. Of course I check is something NULL and I don't get any errors.

In dll I have 5 functions:

dllMain (here I only set global hInstance variable, which is in shared memory ):

BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD fdwReason,LPVOID lpvReserved)
{
    switch(fdwReason)
    {
        case DLL_PROCESS_ATTACH:
        {
            if (hInstance == NULL)
            {
                hInstance = hinstDLL;                   
            }
            break;
        }
        ...
    }
    return TRUE;
}

Hook ( HandleofTarget is the HWND, which I get from FindWindow ; I use this function in injector ):

extern "C" __declspec(dllexport) bool hook( HWND HandleofTarget)
{
    hTarget=HandleofTarget;
        
    hhook=SetWindowsHookEx(WH_CBT,cbtHookProc,hInstance, GetWindowThreadProcessId(hTarget,NULL));
    if(hhook==NULL)
        return 0;
    else
        return 1;
}

Unhook ( here I unhook hooks - I use this function in injector):

extern "C" __declspec(dllexport) void unhook(void)
{
    if(hhook != NULL)
       UnhookWindowsHookEx( hhook );
}

cbtHookProc ( hook callback, where I change window procedure ):

LRESULT CALLBACK cbtHookProc( int code, WPARAM wParam, LPARAM lParam )
{
    if( code < 0 ) return CallNextHookEx( 0, code, wParam, lParam );
    
    if (code == HCBT_ACTIVATE)
    {
        if((HWND)(wParam)==hTarget)              
        {
            if(done == FALSE)
            {
                g_OldWndProc =(WNDPROC)(SetWindowLongPtr ( (HWND)(wParam), GWLP_WNDPROC,reinterpret_cast<LONG_PTR>(  NewWndProc )));
                done = TRUE;
            }
        }   
    }
    
    return CallNextHookEx( 0, code, wParam, lParam );
}

NewWndProc ( new Window procedure, where I would like to block maximalize ):

LRESULT CALLBACK NewWndProc( HWND hwnd, UINT mesg, WPARAM wParam, LPARAM lParam )
{
    switch( mesg )
    {
    case WM_SYSCOMMAND:
        {
            if(wParam == SC_MAXIMIZE)
            {
                return 1;
            }
        }
        break;
    }

     return CallWindowProc( g_OldWndProc, hwnd, mesg, wParam, lParam );
}

When I test this dll with other apps - it works. When I use this dll with web browser like Internet Edge and Google Chrome - it doesn't works. That web browser, which I try injected works slower, but I can still maximalize that window. When I debuq dll, in web browser after SetWindowsHookEx I see that hook is not NULL, but my code doesn't go to cbtHookProc. What is going on with web browser?

UPDATE:

One more time - thank you Strive Sun - MSFT for helping me. I change the lines in cbtHookProc, but it still doesn't work. My cbtHookProc is don't called by webBrowser - that is problem.

When I looked at your gif I see something what I don't have and I think that is the problem. My injector app looks like this:

    hDll = LoadLibrary( L"dllka10" );
    hHookedWindow=FindWindow(TEXT("Chrome_WidgetWin_1"),TEXT("Nowa karta - Google Chrome"));

    if( hDll && hHookedWindow)
    {
        qDebug()<<"hDll and hHookedWindow are not NULL!";
        funHook =( MYPROC2 ) GetProcAddress( hDll, (LPCSTR) "hook" );
        funUnhook = ( MYPROC ) GetProcAddress( hDll, (LPCSTR) "unhook" );
        if( funHook )
        {
            qDebug()<<funHook(hHookedWindow);
        }
    }

I don't use CreateThread(). Is it important here?

UPDATED 2

LRESULT CALLBACK cbtHookProc( int code, WPARAM wParam, LPARAM lParam )
{
    if( code < 0 ) return CallNextHookEx( 0, code, wParam, lParam );
    
    std::fstream file;
    file.open("C:\\Users\\tom\\Desktop\\logs.txt",std::ios::out|std::ios::app);
    file<<"In cbtHook function!"<<std::endl;
    file.close();
        
    if (code == HCBT_MINMAX)
    {
        if (LOWORD(lParam) == SW_SHOWMAXIMIZED)
        {
            return 1;
        }
        
    }

    return CallNextHookEx( 0, code, wParam, lParam );
}

When I run chrome application - my logs.txt is empty. When I run other app - I have logs.

UPDATED 3

In my dll I have:

#ifdef __GNUC__
HWND hTarget  __attribute__((section (".shared"), shared))   =NULL;
HWND hApp  __attribute__((section (".shared"), shared))        = NULL;
bool done   __attribute__((section (".shared"), shared))            =FALSE;
HINSTANCE hInstance    __attribute__((section (".shared"), shared))                 =NULL;
HHOOK hhook       __attribute__((section (".shared"), shared))          = NULL;
WNDPROC g_OldWndProc   __attribute__((section (".shared"), shared))                    = NULL;
#endif
#ifdef _MSC_VER
#pragma data_seg(".shared")
HWND hTarget=NULL;
HWND hApp = NULL;
bool done=FALSE;
HINSTANCE hInstance=NULL;
HHOOK hhook = NULL;
WNDPROC g_OldWndProc = NULL;
#pragma data_seg()
#pragma comment(linker, "/section:.shared,RWS")
#endif

in my injector I don't have any pragma - I have only ( QT ):

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <iostream>
#include "string.h"
#include "windows.h"

Answer 1

I can't reproduce your problem, but you can try another easier method.

HCBT_MINMAX : Specifies, in the low-order word, a show-window value (SW_) specifying the operation. For a list of show-window values, see the ShowWindow. The high-order word is undefined.

  if (code == HCBT_MINMAX)
    {
        if (LOWORD(lParam) == SW_SHOWMAXIMIZED)
        {
            return 1;
        }
        
    }

No need to use HCBT_ACTIVATE to obtain window handles and compare their handles.

Updated:

Code works fine.

My code sample:

DLL:

// dllmain.cpp : Defines the entry point for the DLL application.
#include "pch.h"
#include "stdio.h"
#include <windows.h>


HHOOK hCBT = NULL;
HWND hTarget;
HMODULE thisModule;


LRESULT CALLBACK _cbtProc(int code, WPARAM wParam, LPARAM lParam)
{ 
    if (code < 0) return CallNextHookEx(0, code, wParam, lParam);

    if (code == HCBT_MINMAX)
    {
        if (LOWORD(lParam) == SW_SHOWMAXIMIZED)
        {
            return 1;
        }
        
    }
    return CallNextHookEx(0, code, wParam, lParam);
}

#ifdef __cplusplus    //If used by C++ code.
extern "C" {        //we need to export the C interface
#endif
    __declspec(dllexport) BOOL WINAPI InstallHooks(HWND HandleofTarget)
    {
        hTarget = HandleofTarget;
        
        DWORD tid = GetWindowThreadProcessId(hTarget, NULL);
        hCBT = SetWindowsHookEx(WH_CBT, _cbtProc, thisModule, tid);

        return (hCBT) ? TRUE : FALSE;
    }
#ifdef __cplusplus
}
#endif

#ifdef __cplusplus    //If used by C++ code.
extern "C" {        //we need to export the C interface
#endif
    __declspec(dllexport) void WINAPI RemoveHooks()
    {   
         UnhookWindowsHookEx(hCBT);
         MessageBox(NULL, L"unhook", L" ", MB_OK);
         hCBT = NULL;
    }
#ifdef __cplusplus
}
#endif

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    thisModule = hModule;
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

main.cpp

#include <Windows.h>
#include <stdio.h>
#include <psapi.h>
#include <shlwapi.h>
#include <tchar.h>

#pragma comment(lib,"Kernel32.lib")
#pragma comment(lib,"shlwapi.lib")
#pragma comment(linker, "/SECTION:.shared,RWS")

using namespace std;
HINSTANCE hinstDLL;
typedef void (*RemoveHooks)();

DWORD __stdcall CreateThreadFunc(LPVOID)
{
    while (1)
    {
        if (GetAsyncKeyState(0x50) & 0x0001)
        {
            RemoveHooks removeHooks = (RemoveHooks)GetProcAddress(hinstDLL, "RemoveHooks");
            removeHooks();
        }
    }
    return 0;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {
    if (message == WM_DESTROY) {      
        PostQuitMessage(0);
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
};

int main()
{
    HWND hwnd = FindWindow(L"Chrome_WidgetWin_1", L"Google Translate - Google Chrome");
 
    CreateThread(NULL, 0, CreateThreadFunc, 0, 0, 0);

    hinstDLL = LoadLibrary(TEXT("D:\\Start from 11.2\\WM_CBT_DLL\\x64\\Debug\\WM_CBT_DLL.dll")); 
    BOOL(*InstallHooks)(HWND);
    InstallHooks = (BOOL(*)(HWND)) GetProcAddress(hinstDLL, "InstallHooks");
    
    BOOL l = InstallHooks(hwnd);

    int err = GetLastError();

    MSG msg = {};

    while (GetMessage(&msg, NULL, 0, 0)) {       
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}