How to Stop Race condition on t3 pages api

dupe

18 Replies

StylyOP•15mo ago

@cfkeef

Keef•15mo ago

so how are you fetching this data if balance x is owned by user y, me looking up balance z as user a shouldn't really be a thing happening

StylyOP•15mo ago

? on prisma

Keef•15mo ago

share your query

StylyOP•15mo ago

await prisma.token.update({where:{token:token!.token}, data:{used:true}});

await prisma.token.update({where:{token:token!.token}, data:{used:true}});

il use this one as it also applies, since its shorter

Keef•15mo ago

This really shouldnt' be happening if your query looks something like

SELECT * FROM BALANCE WHERE id="jake"

SELECT * FROM BALANCE WHERE id="jake"

Another user querying for paul shouldn't get this unless you are querying very broadly in this case token narrows it for you Does balance have the token on it and you are using it to query?

StylyOP•15mo ago

the problem is if you send 2 requests at this api endpoint you can use a token twice instead of once but those requests have to happen at the same time

Keef•15mo ago

is the token some kind of session token? or csrf? or what Are you changing it after each request?

StylyOP•15mo ago

its more like a giftcard, i do

let token = await prisma.token.findFirst({where:{token:req.body.token}})
        if(token==null || token?.used) return res.status(418).end()

let token = await prisma.token.findFirst({where:{token:req.body.token}})
        if(token==null || token?.used) return res.status(418).end()

before that query

Keef•15mo ago

Is it possible for users to fetch more than one balance at a time?

StylyOP•15mo ago

yes, this exploit applies to almost all of my api endpoints

Keef•15mo ago

Yeah this is probably too simple for your use case if you are trying to limit requests to some balance or some limit What i've done in the past is use redis and you can just claim tokens from there. Its single threaded so atomicity is a given for you. Before each request claim a token by pulling it out of redis then send it away

StylyOP•15mo ago

on, the createID they both run and check the if at the same time so they pass

Keef•15mo ago

You can look at distributed locks if you want which try to solve this over a distributed system which serverless is

StylyOP•15mo ago

there probably is a setting in prisma for this or next

Keef•15mo ago

nope you can probably do locking in the database you use but i haven't touched that before Lock the token at the start of the request flow and when you query skip locked rows you just have to be careful about releasing the lock if the thing fails/succeeds idk if thats given

StylyOP•15mo ago

yea its given

StylyOP•15mo ago

@cfkeef i feel like this should be in the t3 wiki

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How to Stop Race condition on t3 pages api