Sniper bug improvement

[ZantetsukenGT]

When a player gets killed, and after the respawn_time passes, the player will briefly be streamed out and then streamed in to be respawned, and during that brief time if that player gets shot by any weapon, the library will set the issuerid to INVALID_PLAYER_ID, which later on will falsely trigger the sniper bug detection. This behavior can be quickly reproduced with SetRespawnTime(0) and respawning the player on the spot.

This PR is only relevant to servers with lag_compensation disabled.

This PR also added a new enum variant namely WC_SNIPER_BUG which can be used in OnInvalidWeaponDamage.

[ADRFranklin]

Why make a new enum item when you could just return WC_NO_DAMAGED or WC_NO_ISSUER. Returning the sniper bug enum value doesn't really offer any new information, that wouldn't already be understood with the existing enum values.

[ZantetsukenGT]

That's debatible, I added the extra enum variant long time ago since it would be easier to use in OnInvalidWeaponDamage as no further checks are needed to know what triggered it and under what circumstance.

99% of the time this sniper bug check is triggered by the actual sniper bug, the other 1% of the time, by cj with his tec9 bug.

Though further checks are still needed to distinguish sniper bug from cj, I still consider a new enum variant as more ergonomic option to the library user.

I will change it back to WC_NO_ISSUER to keep compatibility with current implementations.

[ZantetsukenGT]

I came out with a cleaner solution, applying the same logic from OnPlayerGiveDamage: reject damage when either player is streamed out.

Let me know your thoughts about this, imo this should've been the default behavior.

[NexiusTailer]

There shouldn't be returning 0
https://github.com/oscar-broman/samp-weapon-config/pull/246/files#diff-b22ee17f67f3abb181cf164d690011a5abe341533db8673200a945bf7b386ecaR3599

Because most of damage at least from grenade explosions and fire may be completely blocked when issuerid just died (but it doesn't mean that the damage should be dropped, for example, if a grenade or molotov cocktail detonated only after his death).

The current way with resetting issuerid to invalid id is the best solution to both prevent damage spoofing and keep a real damage apply in some specific cases like mentioned.

[ZantetsukenGT]

An additional check can be added around the same line to allow all explosion or fire and reset issuerid to invalid id, but block the remaining weapons when they deal unstreamed damage.

It may not be the cleanest but it could work out and performance hit will be negligible at best and potentially faster since we are blocking earliler when this situation arises.

In any case, let me know your thoughts, should I continue this by adding the explosion and fire check or revert to what I initially had without the additional enum, which specifically targets the sniper bug.

[NexiusTailer]

Well you can also check for lag_compensation and do your logic (dropping the damage) if it's disabled if you said it's relevant only for non-lagcomp servers. Anyway most of people use lagcomp enabled and they won't need this for any weapon you'll try to check for.

Something like this I suppose:

// Will be applied on fire, explosion, vehicle and heliblades (carpark) damage
// Both players should see eachother, if playerid claims to keep issuerid valid
if ((!IsPlayerStreamedIn(playerid, issuerid) && !WC_IsPlayerPaused(issuerid)) || !IsPlayerStreamedIn(issuerid, playerid)) {
	if (s_LagCompMode) {
		// Probably fake or belated damage, so let's just reset issuerid
		issuerid = INVALID_PLAYER_ID;
	} else {
		// Also could be a sniper bug, reject the hit then
		AddRejectedHit(playerid, damagedid, HIT_UNSTREAMED, weaponid, damagedid);
		return 0;
	}
}