NIP05: warn about CORS policies that may inhibit JS apps

JS Nostr apps such as Branle may not be able to load `nostr.json` files due to CORS policies.  Update NIP05 to warn about this and provide hints for troubleshooting and fixing the issue.
This commit is contained in:
David A. Harding 2022-05-07 08:31:02 -10:00 committed by fiatjaf
parent d7a4aad4a0
commit 57b86d2482

13
05.md
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@ -50,3 +50,16 @@ Clients may treat the identifier `_@domain` as the "root" identifier, and choose
### Reasoning for the `/.well-known/nostr.json?name=<local-part>` format
By adding the `<local-part>` as a query string instead of as part of the path the protocol can support both dynamic servers that can generate JSON on-demand and static servers with a JSON file in it that may contain multiple names.
### Allowing access from Javascript apps
Javascript Nostr apps may be restricted by browser [CORS][] policies that prevent them from accesing `nostr.json` on the user's domain. When CORS prevents JS from loading a resource, the JS program sees it as a network failure identical to the resource not existing, so it is not possible for a pure-JS app to tell the user for certain that the failure was caused by a CORS issue. JS Nostr apps that see network failures requesting `nostr.json` files may want to recommend to users that they check the CORS policy of their servers, e.g.:
```bash
$ curl -sI https://example.com/.well-known/nostr.json?name=bob | grep ^Access-Control
Access-Control-Allow-Origin: *
```
Users should ensure that their `nostr.json` is served with the HTTP header `Access-Control-Allow-Origin: *` to ensure it can be validated by pure JS apps running in modern browsers.
[CORS]: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS