C++ redirect outgoing connections

Question

Is there any way in C++ on windows to monitor a program and redirect any outgoing requests it makes on a specific port? I have a simple C++ http proxy and want it to be able to automatically redirect all browser requests on port 80 through itself.

Answer 1

The simple way to do it is to create a Windows kernel hook to trap socket requests and reroute them to your proxy.

Some useful documentation on this is:

http://www.internals.com/articles/apispy/apispy.htm

If you're using Windows Vista or better, consider Windows Filtering Platform (WFP):

http://www.microsoft.com/whdc/device/network/wfp.mspx

Also consider looking at Detours (commercial) and EasyHook (free). They significantly simplify the process of writing hooks and redirecting API calls (both Win32 and Application).