Hello! im trying to allow a domain through CORS using https://developers.cloudflare.com/workers/examples/cors-header-proxy I have a frontend sitting at domainA.com that calls an api at domainB.com for some reason I get this whenever a request fails

workerd/server/server.c++:2347: error: Uncaught exception: kj/async-io-win32.c++:385: failed: WSARecv(): #64 The specified network name is no longer available.
stack: 7ff680e88950 0 0 0 0

doesnt seem like its a workers issue since stack overflow wasnt helpful but also I may be doing this all wrong (exact code https://pastebin.com/dT4G1xnE)

Are you getting this error consistently? Does a redeploy of the Worker fix it?

Local dev with wrangler

This seems to be an issue with the local Worker simulator (workerd) - can you try restarting your PC?

You on Windows by the way? That error sounds very similar to one that Windows would throw

Yah I did. Probably windows is to blame

Ah

Hey erisa!

Hi

That’s what I saw too

Haha

Well thanks y’all! Btw is this how I’m supposed to go about this cross origin thing?

Basically, for any response sent by Domain B, you need to add the following headers:

"Access-Control-Allow-Methods": "POST,GET"

or other methods you use

"Access-Control-Allow-Headers": "Content-Type"

or other headers you use (such as Authorization)

"Access-Control-Allow-Origin": "domaina.com"

or other domains you call from

You can bypass the local runtime by using

wrangler dev --remote

btw

Those headers need to be returned on all responses returned from that domain, including OPTIONS method

Oh interesting , thanks!

Yup. And those headers also need to be returned on the POST (both on the preflight, OPTIONS, as well as the final POST request) otherwise the browser will reject it

This seems like basic web dev that I just glossed over lol. Thanks for all ur help

No worries, CORS can be confusing. 🙂

Yeah now I’m looking in chrome console and it’s complaining about cors

If you open the Network tab, Chrome should also tell you which request is failing (the OPTIONS or the POST) too

Hey Isaac, on your blog what does it mean when you advertise routes? Like why do you need to do it?

Oh. So basically, when you go to a web page, the network connection may go through multiple providers:

Your Internet Service Provider -> possibly through many different providers, like other ISPs in your area -> the final destination, like Cloudflare.

I have my own IP addresses (well, on loan from a friend but I can use them as I like). In order to make sure other people can reach my addresses, I "advertise routes" which means I tell people "hey if you want to reach me you can jump through this provider and then this other provider and then get to me". Like:

Your ISP -> in my case, via GoCodeIT (an ISP of sorts) -> me

That way I can control exactly how people reach my internet, and if my upstream provider goes down (GoCodeIT) I can just switch providers or even have it automatically use another one so that I don't have downtime.

Dude that’s sick!

Yeah it's pretty neat! It's how the internet works in general - if Cloudflare stopped advertising routes, suddenly all your devices wouldn't know how to reach any site on Cloudflare. Similarly, Cloudflare can change how they advertise routes to make things faster or more optimized for users.

I remember reading about that one time a router was misconfigured and cloudflare disappeared from the internet

Exactly! That was an issue with their route advertisements.

Ohh that makes sense

I am getting similar error for Workers Pages with Remix (using Windows) How do I use remote for pages like

wrangler dev --remote

this won't work

wrangler pages dev ./public --remote

Pages doesn't support remote mode at the moment unfortunately

ok, for now downgraded to wrangler 2