Cors error with MetaMask

[8times4]

Describe the bug
There seems to be a CORS error when http://localhost:3000 or http://127.0.0.1:3000 is added to MetaMask.

To Reproduce
Steps to reproduce the behavior:

1. Run blutgang
2. Try adding the designated endpoint to MetaMask
3. Cry because CORS is taking away your joy from life.

Expected behavior
Expected to connect.

Specs:

• OS: Tried through an Envoy proxy in k8s, running on Ubuntu 22.04 and via local M1 Pro Mac.
• Kernel: latest for arm64
• Blutgang version: 0.2.0

Blutgang options:
used the example default config with +1 RPC

• DB mode: [HighThroughput]
• DB compression: [no]
• Cache capacity: [1000000000]
• MA length: [20]
• RPCs used: [llamanodes,merkle,geth]

Additional context
The issue is similar to when --http.corsdomain is not enabled in geth.

[makemake-kbo]

Blutgang doesn't do CORS filtering. It seems that metamask is giving Infura type not known errors in the console when you add it as a new network.

I'll need to dig deeper into whats making it unhappy when i get some free time as im currently at Devconnect

P.S: Frame wallet is more than happy to use blutgang, so its probably just metamask being weird

[8times4]

Thanks for the reply @makemake-kbo, take your time.
So far what I've gathered is that sending an OPTIONS request will throw back a {"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"Invalid Request","data":"Failed to deserialize the JSON body into the target type"}}, however I can only poke Rust code with a stick, so wasn't really able to figure out a solution yet.

[makemake-kbo]

ok, ive seem to have narrowed it down to the JSON not being serialized properly. this might be a problem with either blutgang or a third party library. will have to investigate further

Edit: nvm, that doesnt seem to be it...

Edit 2: The issue seems to stem from the fact that metamask sends a request with an empty body, which blutgang doesnt know what to do with so it rejects and errors it. Heres how the request looks:

"Request"{
   "method":"OPTIONS",
   "uri":"/",
   "version":HTTP/1.1,
   "headers":{
      "host":"127.0.0.1:3000",
      "user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/119.0",
      "accept":"*/*",
      "accept-language":"en-GB,en;q=0.5",
      "accept-encoding":"gzip, deflate, br",
      "access-control-request-method":"POST",
      "access-control-request-headers":"content-type",
      "origin":"moz-extension://8ecf6143-adcf-4e06-9787-d0895acaf7b5",
      "dnt":"1",
      "connection":"keep-alive",
      "sec-fetch-dest":"empty",
      "sec-fetch-mode":"cors",
      "sec-fetch-site":"cross-site"
   },
   "body":"Body(Empty)"
}

Ill have to open an issue on the metamask repo to figure out what exactly its doing because this isnt making a lot of sense.

Edit 3: Issue opened MetaMask/metamask-extension#21803

[8times4]

ok, ive seem to have narrowed it down to the JSON not being serialized properly. this might be a problem with either blutgang or a third party library. will have to investigate further

Edit: nvm, that doesnt seem to be it...

Edit 2: The issue seems to stem from the fact that metamask sends a request with an empty body, which blutgang doesnt know what to do with so it rejects and errors it. Heres how the request looks:

"Request"{
   "method":"OPTIONS",
   "uri":"/",
   "version":HTTP/1.1,
   "headers":{
      "host":"127.0.0.1:3000",
      "user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/119.0",
      "accept":"*/*",
      "accept-language":"en-GB,en;q=0.5",
      "accept-encoding":"gzip, deflate, br",
      "access-control-request-method":"POST",
      "access-control-request-headers":"content-type",
      "origin":"moz-extension://8ecf6143-adcf-4e06-9787-d0895acaf7b5",
      "dnt":"1",
      "connection":"keep-alive",
      "sec-fetch-dest":"empty",
      "sec-fetch-mode":"cors",
      "sec-fetch-site":"cross-site"
   },
   "body":"Body(Empty)"
}

Ill have to open an issue on the metamask repo to figure out what exactly its doing because this isnt making a lot of sense.

Edit 3: Issue opened MetaMask/metamask-extension#21803

Thank you for the update!

[makemake-kbo]

Ive been able to reproduce this locally on my mac, but others have been reporting that they could use blutgang with metamask.

Theres a good chance this is a macos only thing. Ill investigate when i get access to a non macos computer.

[makemake-kbo]

Should be fixed in https://github.com/rainshowerLabs/blutgang/tree/0.3.0. Leaving as open until it gets merged.