Optimize disposable email domain validation using `SISMEMBER` instead of `SMEMBERS`

[unrenamed]

Currently, the validation logic for checking if an email belongs to a disposable domain uses SMEMBERS to retrieve all the domains from the Redis set disposableEmailDomains, followed by an includes() check in the application code. This approach can be inefficient, especially as the size of the set grows, since both the Redis SMEMBERS command and the subsequent membership check have an overall time complexity of O(N).

https://github.com/dubinc/dub/blob/628eb46bfe7012ac3f7d316e0584265b2d999c00/apps/web/lib/actions/create-user-account.ts#L33-L42

Suggested Improvement: To optimize this, you can directly use Redis’s SISMEMBER command, which has a constant time complexity O(1), to check if the domain is part of the set without retrieving all the elements.

Proposed Code Change:

const domain = email.split("@")[1];
const isDisposable = await redis.sismember("disposableEmailDomains", domain);

if (isDisposable) {
  throw new Error(
    "Disposable email addresses are not allowed. If you think this is a mistake, please contact us at support@dub.co",
  );
}

Another benefit the app can get from the proposed solution is lower network overhead: you will avoid fetching the entire set from Redis, reducing the amount of data transferred between Redis and the application.

Links:

• https://redis.io/docs/latest/commands/smembers/
• https://redis.io/docs/latest/commands/sismember/
• https://upstash.com/docs/redis/sdks/ts/commands/set/sismember#sismember

[linear[bot]]

ENG-594 Optimize disposable email domain validation using `SISMEMBER` instead of `SMEMBERS`

[steven-tey]

@unrenamed fantastic suggestion! Feel free to PR, will get this merged 🙏

[steven-tey]

@unrenamed added this to oss.gg btw, feel free to claim this issue and make the PR (instructions here)

[sudipb7]

I made a PR for it https://github.com/dubinc/dub/pull/1311

[unrenamed]

I guess the early bird really does get the worm... 😅

[sudipb7]

😅

[steven-tey]

Since this was @unrenamed's idea, I've closed @sudipb7's PR to give a chance for @unrenamed to make the changes instead.

@unrenamed do you want to comment /assign and get the issue assigned to you by OSS.gg, and create the PR instead?

[unrenamed]

Well, since you've already closed @sudipb7's PR, I guess I can only thank you and create the new one including @devkiran's review comments. Will do in a moment ✍️

[unrenamed]

/assign

[oss-gg[bot]]

Assigned to @unrenamed! Please open a draft PR linking this issue within 48h ⚠️ If we can't detect a PR from you linking this issue in 48h, you'll be unassigned automatically 🕹️ Excited to have you ship this 🚀

[sudipb7]

Understood, no problem at all! Thanks for letting me know.