保护客户端-服务器边界

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

local itemDataFolder = ReplicatedStorage:WaitForChild("ItemData")
local buyItemEvent = ReplicatedStorage:WaitForChild("BuyItemEvent")
local payload = {
	Name = "Ultra Blade",
	ClassName = "Folder",
	Parent = itemDataFolder,
	Price = {
		Name = "Price",
		ClassName = "NumberValue",
		Value = 0, -- 负值也可能被使用，导致给予货币而不是消耗货币！
	},
}

-- 发送恶意有效负载到服务器（这将被拒绝）
print(buyItemEvent:InvokeServer(payload))  -- 输出 "false Invalid item provided"

-- 发送真实物品到服务器（这将会通过！）
print(buyItemEvent:InvokeServer(itemDatafolder["Real Blade"]))  -- 输出 "true" 和如果购买成功的剩余货币

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

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

local function buyItem(player, item)
	-- 检查传递的物品是否不是伪造的，并且在 ItemData 文件夹中
	if typeof(item) ~= "Instance" or not item:IsDescendantOf(itemDataFolder) then
		return false, "Invalid item provided"
	end

	-- 然后服务器可以根据以下示例流程继续处理购买
end

-- 将 "buyItem()" 绑定到远程函数的回调
buyItemEvent.OnServerInvoke = buyItem

local function isNaN(n: number): boolean
	-- NaN 永远不等于自身
	return n ~= n
end

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

-- 脆弱的服务器代码
local function onCreateTradeOffer(player, offeredGold)
    -- 1. 类型检查：这通过了！typeof(NaN) 是 "number"。
    if typeof(offeredGold) ~= "number" then
      return "Invalid offer"
    end

    -- 2. 范围检查：这被绕过了！
    -- (NaN < 0) 为假。 (NaN > 1000000) 也为假。检查无效。
    if offeredGold < 0 or offeredGold > 1000000 then
      return "Offer out of range"
    end

    -- 3. 库存检查：这被绕过了！
    -- (NaN > player.Gold.Value) 也为假。
    if offeredGold > player.Gold.Value then
      return "Not enough gold" 
    end

    -- 脆弱性：用 NaN 黄金创建了一份欺诈性交易报价！
    createTrade(player, {gold = offeredGold})
    return "Trade offer created."
end

--!strict
-- 模块位于 ServerScriptService

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

-- 创建一个限制器，最多允许 `capacity` 事件，以 `capacity / windowSeconds` 令牌的速率重新充满
function TokenBucket.new(capacity: number, windowSeconds: number): TokenBucketT
    assert(capacity >= 1, "capacity must be >= 1")
    assert(windowSeconds > 0, "windowSeconds must be > 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

-- 如果用户将超过其限制，则返回 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

-- 在服务器脚本中的示例用法

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 条消息（容量 5，补充速率 0.5 令牌/秒）
local chatLimiter = TokenBucket.new(5, 10)

ChatRemote.OnServerEvent:Connect(function(player: Player, message: string)
    if not chatLimiter:allow(player.UserId) then
        -- 速度太快：丢弃请求或发送垃圾邮件警告
        return
    end

    -- 处理消息（经过其他验证后）
    broadcastMessage(player, message)
end)

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

脆弱的服务器代码（在 ServerScriptStorage 中的脚本）
local castLightningEvent = game.ReplicatedStorage.CastLightning

-- 此服务器脚本在没有任何验证的情况下将消息中继给每一个人
castLightningEvent.OnServerEvent:Connect(function(player, strikePosition)
    castLightningEvent:FireAllClients(strikePosition)
end)

客户端效果代码
local castLightningEvent = game.ReplicatedStorage.CastLightning

-- 在客户端创建视觉和声音效果
local function createLightningEffect(strikePosition)
    -- 撑开相机的代码
    -- 播放响亮的闪电声音的代码
    -- 创建视觉闪电的代码
    print("Lightning strikes at: " .. tostring(strikePosition))
end

-- 当服务器广播事件时，此客户端运行效果
castLightningEvent.OnClientEvent:Connect(createLightningEffect)

安全的服务器代码
local castLightningEvent = game.ReplicatedStorage.CastLightning
local playerCooldowns = {}
local COOLDOWN_TIME = 3

castLightningEvent.OnServerEvent:Connect(function(player, strikePosition)
    -- 1. 类型验证
    if typeof(strikePosition) ~= "Vector3" then
        return -- 无效类型，静默拒绝
    end

    -- 2. 检查 NaN（NaN ~= NaN 是唯一检测它的方法）
    if strikePosition.X ~= strikePosition.X then
        return -- 包含 NaN，拒绝
    end

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

    -- 4. 示例权限检查
    if not player:GetAttribute("HasLightningSpell") then
        return -- 玩家没有此法术
    end

    -- 5. 示例范围验证
    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 -- 超出范围
    end

    -- 所有检查通过 - 安全广播
    playerCooldowns[player] = tick()
    castLightningEvent:FireAllClients(player, strikePosition)
end)