Best way to hook something on player

[Hedgehog]

I'm trying to hook several actions like WeaponCanUse, TakeDamage, etc (all from SDKHooks) on a player. And after some time of suffering I got this (for some reason it works...):

Syntax: Select all

from core import PLATFORM
from entities.helpers import index_from_pointer
from events import Event
from filters.players import PlayerIter
from memory import Convention, Argument, Return
from memory.hooks import HookType
from players.helpers import pointer_from_userid

funcs = {}


@Event
def player_activate(event):
    userid = event.get_int('userid')

    hook_weapon_can_use(userid)


def hook_weapon_can_use(userid):
    funcs[userid] = pointer_from_userid(userid).make_virtual_function(
        259 if PLATFORM == 'windows' else 260,
        Convention.THISCALL,
        (Argument.POINTER, Argument.POINTER, Argument.POINTER),
        Return.INT
    )

    funcs[userid].add_hook(HookType.POST, on_weapon_can_use)
    print('Hooked: ' + str(userid))


@Event
def player_disconnect(event):
    userid = event.get_int('userid')

    funcs[userid].remove_hook(HookType.POST, on_weapon_can_use)
    print('Unhooked: ' + str(userid))


def load():
    for userid in PlayerIter(return_types=['userid']):
        hook_weapon_can_use(userid[0])


def unload():
    for userid in PlayerIter(return_types=['userid']):
        funcs[userid[0]].remove_hook(HookType.POST, on_weapon_can_use)
        print('Unhooked: ' + str(userid[0]))


def on_weapon_can_use(first, second):
    print('on_weapon_can_use')
    print(index_from_pointer(first[0]))
    print(index_from_pointer(first[1]))
    print(second)

I have a feeling, that it's not the simplest way to do a hook. Am I right? And no signatures, please! :)

[Ayuto]

This is how I would do it.

Syntax: Select all

# =============================================================================
# >> IMPORTS
# =============================================================================
import memory

from memory.manager import manager
from memory.manager import CustomType
from memory.manager import Argument
from memory.manager import Return

from filters.players import PlayerIter

from players.helpers import index_from_pointer
from players.entity import PlayerEntity

from events import Event
from core import PLATFORM



# =============================================================================
# >> GLOBAL VARIABLES
# =============================================================================
# This variable will store the CCSPlayer::Weapon_CanUse() function.
Weapon_CanUse = None


# =============================================================================
# >> CLASSES
# =============================================================================
class CCSPlayer(CustomType, metaclass=manager):
    '''
    This is a reconstruction of the CCSPlayer class.

    You can add virtual functions, normal functions, attributes and arrays.

    You can even extend the class with your own functions, attribute or
    properties!
    '''

    # bool CCSPlayer::Weapon_CanUse(CBaseCombatWeapon*)
    # NOTE: I only pass one "Argument.POINTER". "manager.virtual_function"
    # will automatically add the "this" pointer argument.
    Weapon_CanUse = manager.virtual_function(
        259 if PLATFORM == 'windows' else 260,
        (Argument.POINTER,),
        Return.BOOL
    )
    
    @property
    def player_entity(self):
        '''
        Returns a new PlayerEntity object.
        '''
        
        return PlayerEntity(index_from_pointer(self))


# =============================================================================
# >> LOAD & UNLOAD
# =============================================================================
def load():
    # Try to hook the function
    hook_weapon_can_use()

def unload():
    # Try to unhook the function
    unhook_weapon_can_use()


# =============================================================================
# >> GAME EVENTS
# =============================================================================
@Event
def player_activate(event):
    # Try to hook the function
    hook_weapon_can_use()


# =============================================================================
# >> FUNCTONS
# =============================================================================
def hook_weapon_can_use():
    '''
    Attempts to hook CCSPlayer::Weapon_CanUse().

    It will only succeed if there is at least one player on the server.
    '''

    global Weapon_CanUse

    # Did we already hooked the function?
    if Weapon_CanUse is not None:
        # No need to hook it again
        return

    # Get all player pointers
    players = tuple(PlayerIter(return_types='pointer'))

    # Is there no player on the server?
    if not players:
        # We can't hook this function without a player pointer
        return

    # Get the first player and convert the pointer to a CCSPlayer object
    player = memory.make_object(CCSPlayer, players[0])

    # Add a post hook callback for that function
    player.Weapon_CanUse.add_post_hook(on_weapon_can_use)

    # We will save the Function object, so we can unhook it later without the
    # need of a player
    Weapon_CanUse = player.Weapon_CanUse

def unhook_weapon_can_use():
    '''
    Attempts to unhook CCSPlayer::Weapon_CanUse(). If it wasn't hooked, it
    won't do anything.
    '''

    # Did we hook the function?
    if Weapon_CanUse is not None:
        # Unhook it
        Weapon_CanUse.remove_post_hook(on_weapon_can_use)


# =============================================================================
# >> CALLBACKS
# =============================================================================
def on_weapon_can_use(args, return_value):
    '''
    Called after CCSPlayer::Weapon_CanUse() has been called.

    You will be able to modfiy the return value here! Of course you can also
    modify the arguments.

    @param <args>:
    A StackData object that stores the arguments of CCSPlayer::Weapon_CanUse().

    args[0] is the "this" pointer. It's a player pointer.
    args[1] is a CBaseCombatWeapon pointer. It's the weapon that was checked.

    @param <return_value>:
    Contains the return value that was returned by the original function.

    This will be True if the player can use the weapon, False if he can't use
    it.
    '''

    # Convert the pointer to a CCSPlayer object. If you add more functions or
    # attributes to the reconstructed type, you can do pretty cool stuff.
    player = memory.make_object(CCSPlayer, args[0])

    # You can also reconstruct the CBaseCombatWeapon class, but for now I will
    # leave it as a simple pointer
    weapon_ptr = args[1]
    
    # Print the player's name
    print(player.player_entity.name)

You don't need to hook the function for every player. Once is enough. ;)

[Hedgehog]

OMG, thanks! But what will happen after player, whose pointer we used, disconnect?

UPD: How I can get what I should pass in second argument of virtual_function()?

[Ayuto]

If the player leaves the server, nothing will happen. You script will still work.

UPD: How I can get what I should pass in second argument of virtual_function()?

What exactly do you mean?

[Doldol]

And this is awesome! Makes me happy that the days of Eventscripts are over!

This will eventually find it's way into a full-on library, right?

[Ayuto]

Yeah, it's already quite useful

[Hedgehog]

What exactly do you mean?

I'm talking about 3rd line from this code:

Syntax: Select all

Weapon_CanUse = manager.virtual_function(
        259 if PLATFORM == 'windows' else 260,
        (Argument.POINTER,),
        Return.BOOL
    )

You wrote there Argument.POINTER. But what I should write in other cases?

[Ayuto]

This will tell manager.virtual_function() which argument types the function requires.

Here are some examples:
CCSPlayer::Weapon_CanUse(CBaseCombatWeapon*): As you can see the method only takes one pointer. To be more specific a CBaseCombatWeapon pointer. But the pointer type doesn't matter.

SomeClass::Something(CBaseCombatWeapon*, int, bool): In this case the iterable would look like this: (Argument.POINTER, Argument.INT, Argument.BOOL)

SomeClass::Something2(): This would result in an empty iterable.

This link might help you. http://wiki.sourcepython.com/index.php/memory#Argument

[satoon101]

Another way, without having to wait for a player to join, is to create a bot, use its pointer, and kick it:

Syntax: Select all

from engines.server import EngineServer
from entities.helpers import pointer_from_edict
from filters.players import PlayerIter
from players.bot import BotManager
from players.helpers import userid_from_pointer

create = False

for pointer in PlayerIter(return_types='pointer'):
    break

# Was no player found during iteration?
else:
    create = True
    edict = BotManager.create_bot('test_bot')
    pointer = pointer_from_edict(edict)



# Then, after you have the virtual function, kick it
if create:
    EngineServer.server_command('kickid {0}\n'.format(userid_from_pointer(pointer)))

Also, there is currently a rewrite of the internal use for BaseEntity, but the following should work with the current version. Add a file to your server at ../addons/source-python/data/source-python/entities/virtuals/cstrike/CCSPlayer.ini and put the following inside that file:

Syntax: Select all

[weapon_canuse]
name = _ZN9CCSPlayer13Weapon_CanUseEP17CBaseCombatWeapon
convention = THISCALL
arguments = POINTER,POINTER
return_type = BOOL

Now, you can use the following:

Syntax: Select all

from engines.server import EngineServer
from entities.helpers import index_from_edict
from filters.players import PlayerIter
from memory.hooks import PostHook
from players.bot import BotManager
from players.entity import PlayerEntity
from players.helpers import userid_from_pointer

create = False

for player in PlayerIter(return_types='player'):
    break

# Was no player found during iteration?
else:
    create = True
    edict = BotManager.create_bot('test_bot')
    index = index_from_edict(edict)
    player = PlayerEntity(index)


@PostHook(player.weapon_canuse)
def on_weapon_can_use(args, return_value):
    pass



# Then, after you have the virtual function, kick it
if create:
    EngineServer.server_command('kickid {0}\n'.format(userid_from_pointer(pointer)))

In the new version, once it has been finalized, more virtual functions will be included in the data already. You shouldn't release a script that adds values like this to source-python's data, this is just as an example. The currently implemented virtuals in this manner are CBasePlayer::GiveNamedItem and CBasePlayer::Weapon_Drop for CS:S. No other games are currently supported.