nimbus-eth1 does not work with Metamask wallet

[hmel]

Metamask wallet starts by issuing a OPTIONS / HTTP/1.1 which nimbus responds to with an error

HTTP/1.1 200 OK
Content-Length: 107
Content-Type: text/html; charset=utf-8
Date: Sun, 26 Jun 2022 18:06:05 GMT
Connection: keep-alive

{"jsonrpc":"2.0","id":null,"error":{"code":-32700,"message":"input(1, 0) Error: { expected","data":null}}

Metamask loops on this until timing out and is not able to connect.
Geth responds with

Access-Control-Allow-Headers: Content-Type
Access-Control-Allow-Methods: POST
Access-Control-Allow-Origin: *
Access-Control-Max-Age: 600
Content-Encoding: gzip
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
Date: Sun, 26 Jun 2022 18:13:29 GMT
Content-Length: 23

[jangko]

@hmel, can you also post the metamask wallet complete request header and body? because there is possibility it is a json-rpc's bug.

[hmel]

OPTIONS / HTTP/1.1
Host: localhost:8545
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Access-Control-Request-Method: POST
Access-Control-Request-Headers: content-type
Origin: moz-extension:https://3e7af72b-3e97-4bdd-9a90-f26da6856402
Connection: keep-alive
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: cross-site

[jangko]

I see, this is obviously json-rpc problem, it does not recognize both OPTIONS / and empty body.

[zah]

FWIW, I've added CORS support for the nimbus-eth2 REST API in the following PR:
status-im/nimbus-eth2#3378

Looks like something similar will have to be done here as well.

[jangko]

All HTTP local services in nimbus-eth1 have been upgraded to support CORS for both simple and preflighted request.
Only websocket services still need upgrade, see status-im/nim-websock#121.