hooker.py

# hooker.py 
# deals with hooking of win32 APIs. 
# public domain code. 
 
 
from patcher import *
from tramper import tramper 
from win32api import *
from pytcc import pytcc 
 
 
 
 
 
 
def create_hook (duplicate_api, cparam_types='', prelogic="", postlogic="", restype="int"): 
    """ create_hook (pat, duplicate_api, cparam_types='', prelogic="", postlogic="", restype="int"): 
    """
 
    c_code =\ 
""" 
%s function (int caller, %s) 
{ 
    %s 
    %s  RET = DUPE ( %s ); 
    %s 
    return RET; 
}"""
 
    cargs = '' 
    symbols = '' 
    for arg, char in zip (cparam_types, "ABCDEFGHIJKLMNOPQRSTUVWXYZ"): 
 
        symbols += "%s, " % char 
        cargs += "%s %s, " % (arg, char) 
 
    symbols = symbols [:-2] 
    cargs = cargs [:-2] 
 
    c_code = c_code % (restype, cargs, prelogic, restype, symbols, postlogic) 
    ccompiler = pytcc () 
    ccompiler.add_lib_proc ("msvcrt.dll", "memset") 
    ccompiler.add_symbol ("DUPE", duplicate_api) 
    ccompiler.compile (c_code) 
    ccompiler.relocate () 
     
    hook = ccompiler.get_symbol ("function") 
 
    return (c_code, hook) 
 
 
 
 
 
 
 
 
def hooker (apiname, cparam_types=list(), restype="int", prelogic='',  postlogic='', pid=GetCurrentProcessId(), dllname="kernel32"): 
    """hooker (apiname, cparam_types=list(), restype="int", prelogic='',  postlogic='', pid=GetCurrentProcessId(), dllname="kernel32"): 
    """
 
    pat = patcher () 
     
    params_size = get_cparams_size (cparam_types) 
    pat.set_params_size (params_size) 
     
    pat.set_source_as_api (apiname, dllname) 
 
    hook_size = len (get_patch (pat.destination, pat.params_size)) 
    tramp = tramper (pat.source, hook_size) 
    pat.duplicate_api = tramp 
 
    hook_ccode, hooks = create_hook (tramp, cparam_types, prelogic, postlogic, restype) 
    pat.c_code = hook_ccode 
    pat.set_destination (hooks) 
     
    return pat 
 
 
 
 
 
 
 
 
if __name__ == '__main__': 
 
    # Test. 
 
 
    hook = hooker (\ 
         
        # API to hook 
        apiname="OpenProcess", 
 
        # the DLL the API is in.  (defaults to kernel32)   
        dllname="kernel32", 
         
        # (required) API parameter types. In our hook these get translated to the names A,B,C...respectively. 
        cparam_types=["int", "int", "int"], 
 
        # (required) the API return type. 
        restype="int", 
 
        # (optional) this is the code in our hook wich is executed Before the real API. 
        prelogic="if (C==1) {return 1111;}", 
 
        # (optional) this is the code in our hook wich is executed After the real API.   The real API's return value is named RET. 
        postlogic="if (RET) {return 0;}"
        ) 
 
     
    # hook API. 
    # hook automatically unhooks itself and cleans up when it isnt refered to anymore. 
    hook.patch () 
 
    print "Calling hooked OpenProcess api with process id as 1."
    ret = windll.kernel32.OpenProcess (0x1f0fff, 0, 1) 
     
    print "Return value: %s" % ret 
    if ret == 1111: print "This test was sucesful."
    else: print "Return value is unexpected."
 
    # unhook API. 
    # hook.unpatch () 
         
 
 
#cad