保護客戶端與伺服器的邊界

LocalScript in StarterPlayerScripts
local ReplicatedStorage = game:GetService("ReplicatedStorage")

local itemDataFolder = ReplicatedStorage:WaitForChild("ItemData")
local buyItemEvent = ReplicatedStorage:WaitForChild("BuyItemEvent")
local payload = {
	Name = "超級刀",
	ClassName = "Folder",
	Parent = itemDataFolder,
	Price = {
		Name = "Price",
		ClassName = "NumberValue",
		Value = 0, -- 負值也可用，會導致給予貨幣而不是扣除它！
	},
}

-- 發送惡意有效負載到伺服器（這將被拒絕）
print(buyItemEvent:InvokeServer(payload))  -- 輸出 "false Invalid item provided"

-- 發送真實物品到伺服器（這將通過！）
print(buyItemEvent:InvokeServer(itemDataFolder["真實刀"]))  -- 輸出 "true" 和剩餘貨幣，如果購買成功

Script in ServerScriptStorage
local ReplicatedStorage = game:GetService("ReplicatedStorage")

local itemDataFolder = ReplicatedStorage:WaitForChild("ItemData")
local buyItemEvent = ReplicatedStorage:WaitForChild("BuyItemEvent")

local function buyItem(player, item)
	-- 檢查傳遞的項目是否未被偽造並且在 ItemData 文件夾中
	if typeof(item) ~= "Instance" or not item:IsDescendantOf(itemDataFolder) then
		return false, "無效的物品提供"
	end

	-- 伺服器然後可以根據以下示例流程來處理購買
end

-- 將 "buyItem()" 綁定到遠程函數的回調
buyItemEvent.OnServerInvoke = buyItem

local function isNaN(n: number): boolean
	-- NaN 永遠不等於其自身
	return n ~= n
end

local function isInf(n: number): boolean
	-- 數字可能是 -inf 或 +inf
	return math.abs(n) == math.huge
end

-- 脆弱的伺服器代碼
local function onCreateTradeOffer(player, offeredGold)
    -- 1. 類型檢查：這通過！typeof(NaN) 是 "number"。
    if typeof(offeredGold) ~= "number" then
      return "無效報價"
    end

    -- 2. 範圍檢查：這被繞過了！
    -- (NaN < 0) 是錯的。（NaN > 1000000）也是錯的。檢查不會做任何作用。
    if offeredGold < 0 or offeredGold > 1000000 then
      return "報價超出範圍"
    end

    -- 3. 庫存檢查：這被繞過了！
    -- (NaN > player.Gold.Value) 是錯的。
    if offeredGold > player.Gold.Value then
      return "金額不足" 
    end

    -- 脆弱性：創建一個包含 NaN 金幣的欺詐交易報價！
    createTrade(player, {gold = offeredGold})
    return "交易報價已創建。"
end

--!strict
-- 模塊位於 ServerScriptService 中

type UserId = number

type Bucket = {
    tokens: number,
    last: number,
}

type TokenBucketT = {
    capacity: number,
    refillPerSecond: number,
    buckets: { [UserId]: Bucket },

    allow: (self: TokenBucketT, userId: UserId) -> boolean,
}

local TokenBucket = {}
TokenBucket.__index = TokenBucket

-- 創建限制器，最多允許 `capacity` 事件，以 `capacity / windowSeconds` 的速度重新填充令牌，每秒
function TokenBucket.new(capacity: number, windowSeconds: number): TokenBucketT
    assert(capacity >= 1, "capacity 必須 >= 1")
    assert(windowSeconds > 0, "windowSeconds 必須 > 0")

    local self: TokenBucketT = {
        capacity = capacity,
        refillPerSecond = capacity / windowSeconds,
        buckets = {},
    }
    return (setmetatable(self, TokenBucket) :: any) :: TokenBucketT
end

local function refill(b: Bucket, now: number, cap: number, rate: number)
    local elapsed = now - b.last
    if elapsed > 0 then
        b.tokens = math.min(cap, b.tokens + elapsed * rate)
        b.last = now
    end
end

-- 如果用戶會超過其限制則返回 false
function TokenBucket:allow(userId: UserId): boolean
    local now = time()
    local b = self.buckets[userId]
    if not b then
        b = { tokens = self.capacity, last = now }
        self.buckets[userId] = b
    else
        refill(b, now, self.capacity, self.refillPerSecond)
    end

    if b.tokens >= 1 then
        b.tokens -= 1
        return true
    end
    return false
end

return TokenBucket

-- 示例用法在一個伺服器腳本中

local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local ServerScriptService = game:GetService("ServerScriptService")

local TokenBucket = require(ServerScriptService.TokenBucket)
local ChatRemote = ReplicatedStorage:WaitForChild("ChatRemote") :: RemoteEvent

-- 每 10 秒 5 條消息（容量 5，以 0.5 令牌/秒的速度重新填充）
local chatLimiter = TokenBucket.new(5, 10)

ChatRemote.OnServerEvent:Connect(function(player: Player, message: string)
    if not chatLimiter:allow(player.UserId) then
        -- 太快了：丟棄請求或發送垃圾郵件警告
        return
    end

    -- 處理消息（在其他驗證之後）
    broadcastMessage(player, message)
end)

-- 清理以防止內存泄漏
Players.PlayerRemoving:Connect(function(p: Player)
    chatLimiter.buckets[p.UserId] = nil
end)

脆弱的伺服器代碼 (script in ServerScriptStorage)
local castLightningEvent = game.ReplicatedStorage.CastLightning

-- 此伺服器腳本將消息不經驗證地轉發給每個人
castLightningEvent.OnServerEvent:Connect(function(player, strikePosition)
    castLightningEvent:FireAllClients(strikePosition)
end)

客戶端效果代碼
local castLightningEvent = game.ReplicatedStorage.CastLightning

-- 在客戶端創建視覺和聲音效果
local function createLightningEffect(strikePosition)
    -- 震動鏡頭的代碼
    -- 播放響亮的閃電聲音的代碼
    -- 創建視覺閃電彈的代碼
    print("閃電擊中位置：" .. tostring(strikePosition))
end

-- 當伺服器廣播事件時，該客戶端運行效果
castLightningEvent.OnClientEvent:Connect(createLightningEffect)

安全伺服器代碼
local castLightningEvent = game.ReplicatedStorage.CastLightning
local playerCooldowns = {}
local COOLDOWN_TIME = 3

castLightningEvent.OnServerEvent:Connect(function(player, strikePosition)
    -- 1. 類型驗證
    if typeof(strikePosition) ~= "Vector3" then
        return -- 無效類型，靜默拒絕
    end

    -- 2. 檢查 NaN（NaN ~= NaN 是唯一的檢測方式）
    if strikePosition.X ~= strikePosition.X then
        return -- 包含 NaN，拒絕
    end

    -- 3. 示例速率限制
    local lastCast = playerCooldowns[player] or 0
    if tick() - lastCast < COOLDOWN_TIME then
        return -- 仍在冷卻中
    end

    -- 4. 示例許可檢查
    if not player:GetAttribute("HasLightningSpell") then
        return -- 玩家沒有這個法術
    end

    -- 5. 示例範圍驗證
    local character = player.Character
    local humanoidRootPart = character and character:FindFirstChild("HumanoidRootPart")
    if not humanoidRootPart then
        return
    end

    local distance = (humanoidRootPart.Position - strikePosition).Magnitude
    if distance > 100 then
        return -- 超出範圍
    end

    -- 所有檢查通過 - 可以安全廣播
    playerCooldowns[player] = tick()
    castLightningEvent:FireAllClients(player, strikePosition)
end)