Shulou(Shulou.com)06/03 Report--

This article mainly introduces what the parameters of windows hook are, which can be used for reference by interested friends. I hope you can learn a lot after reading this article.

Hook is a platform for the Windows message handling mechanism, on which an application can set subroutines to monitor certain messages in a specified window, and the monitored window can be created by other processes.

What is the windows hook?

When the message arrives, it is processed before the target window handler. The hook mechanism allows applications to intercept and process window messages or specific events. A hook is actually a segment of a program that handles messages and is hung into the system through a system call. Whenever a specific message is sent, the hook program captures the message before it reaches the destination window, that is, the hook function gets control first. At this point, the hook function can either process (change) the message, or continue to deliver the message without processing, or force the delivery of the message to end. HookAPI refers to the programming interface that Windows opens to programmers, so that the operating system can be controlled at the user level, that is, general applications need to call API to complete certain functions. HookAPI means that these applications can be intercepted before calling the real system API, so as to do some processing and then call the real API to complete the function.

In fact, the Windows system is based on the event-driven mechanism, to put it bluntly, the whole system is realized through the transmission of messages. Hook is a very important system interface in Windows system, which can intercept and process messages sent to other applications to complete the functions that are difficult for ordinary applications to achieve.

It can be seen that many special and useful functions can be achieved by using hooks. Therefore, it is necessary for senior programmers to master the programming method of hooks.

There are many kinds of hooks, each of which can intercept and process the corresponding messages, such as keyboard hooks can intercept keyboard messages, shell hooks can intercept, start and close application messages, and so on.

Use the WH_GETMESSAGE hook in the example program, which monitors Windows messages delivered to the message queue.

Hooks can be divided into thread hooks and system hooks. Thread hooks monitor event messages of specified threads, and system hooks monitor event messages of all threads in the system. Because system hooks affect all applications in the system, hook functions must be placed in a separate dynamic link library (DLL).

Several key Technologies for realizing windows Hook Mechanism

Windows hook program, need to use several sdk in the api function. The prototypes and descriptions of these functions are listed below:

Hhooksetwindowshookex (intidhook,hook_proclpfn,hinstancehmod,dworddwthreadid)

The parameters are described as follows:

Idhook: type of hook

Lpfn: address of hook handler

Hmod: module handle that contains hook functions

Dwthreadid: monitoring thread of the hook

Function description: the function will hang a hook of the type specified by idhook in the system to monitor and process the corresponding specific message.

Boolunhookwindowshookex (hhookhhk)

Function description: the function will undo the hook specified by hhk.

Lresultcallnexthookex (hhookhhk,intncode,wparamwparam,lparamlparam)

Function description: the function passes the message down, and the next hook processing will intercept the message.

Thank you for reading this article carefully. I hope the article "what are the implementation parameters of windows hook" shared by the editor will be helpful to you. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.