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[CODE] 4.0 server damage hook [message #470315] Sat, 30 June 2012 12:38
iRANian is currently offline  iRANian
Messages: 4300
Registered: April 2011
Karma: 0
General (4 Stars)
This hooks the start of 4.0's DefenseObjectClass::Apply_Damage() hook, executes its code and then jumps 8 byte down 4.0's hook (so the 4.0 code is executed like normally). All damage done should pass through this hook but I'm not sure. I didn't include the definition of some of the hooking functions I use because I'm lazy. Took me a bit to find an Apply_Damage() function that hit my breakpoint..

int Calculate_Address_From_Displacement(int JMPStartAddress)
{
	char OpCodes[5];
	int Displacement, Address;

	Hooking::ReadMemory(JMPStartAddress, OpCodes, 5); // 0x004B4910 is where the JMP opcode (E9) starts, next 4 are the displacement/relative address

	memcpy(&Displacement, OpCodes+1, sizeof(char)*4); // OpCodeBuffer+1 or we'll also read the JMP opcode

	Address = JMPStartAddress + 5 + Displacement;
	return Address;
}

Hook *ApplyDamageHook = new Hook;
int TTApplyDamageAddress = 0;
int TTApplyDamageJMPAddress = 0;

bool _cdecl Apply_Damage_Hook(DefenseObjectClass *Defense, OffenseObjectClass *Offense, float DamageMultiplier, int Unk1)
{
	Console_Output("Warhead = %d\n",Offense->Get_Warhead());
	Console_Output("Unk1 = %d\n", Unk1);
	Console_Output("Health = %f\n", Defense->Get_Health());
	Console_Output("Damage = %f\n", Offense->Get_Damage());
	Console_Output("Multiplier = %f\n", DamageMultiplier);
	Console_Output("Damager = %s, Victim = %s\n", Commands->Get_Preset_Name(Offense->Get_Owner()), Commands->Get_Preset_Name(Defense->Get_Owner()));

	return true;
}

void _declspec(naked) ApplyDamageHook_Glue()
{
	_asm
	{
		push ebp
		mov ebp, esp
		push ecx // save ecx
		push [ebp+0x10]
		push [ebp+0xC]
		push [ebp+8]
		push ecx
		call Apply_Damage_Hook
		add esp, 16

		pop ecx // restore ecx
	
		test al, al
		jz NoDamage

		pop ebp
		mov al, 1
		mov edi, TTApplyDamageJMPAddress
		jmp edi

NoDamage:
		pop ebp
		retn 0ch
	}
}

/* in your installation function add: */

	TTApplyDamageAddress = Calculate_Address_From_Displacement(0x00689780); // Hook from  DefenseObjectClass::Apply_Damage
	TTApplyDamageJMPAddress = TTApplyDamageAddress + 8;
	Console_Output("TT Apply Damage address = 0x%X\n", TTApplyDamageAddress);
	ApplyDamageHook->Install('\xE9', TTApplyDamageAddress, (int)&ApplyDamageHook_Glue, ""); // jump hook
	
/* end installation function */


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Scripts 4.0 private beta tester since May 2011.

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