Option to add extension based on MIME type to URL from upload

[laanwj]

Currently at least nostrudel pastes the url field from the blob descriptor from an uploaded image directly into a nostr post. But nostr clients won't show an image when the URL doesn't end with an image extension such as jpeg, png, webp.

So from a usability point of view it would be useful if the blossom server added the extension. But this means that the server needs a map from upload MIME types to extensions, this isn't always straighforward.

Ostensibly, clients could also do this client-side (adding an extension is always allowed by the blossom protocol). And i imagine there are also non-nostr uses for blossom. So i'm not 100% sure this is a good thing to do server-side.

BUD 2 doesn't specify this, currently. See also discussion in hzrd149/blossom#25 and hzrd149/blossom#26 .

[0xtrr]

I think that makes perfectly sense, the server always has the context of the file so we could easily always serve with the filetype at the end. I don't think this breaks anything with the protocol so if you have any code for this, I'll happily review it. I can also try to add it after I get tests added (probably not this weekend).

[laanwj]

i've done some research here.

Easiest would be to use the mime2ext crate. This is compiled from a static version of mime-db, so will include pretty much every possible file type. Alternatively, if you prefer not to add a dependency, we could use an hardcoded list of media mime types that people are likely to upload.

[0xtrr]

I don't mind adding the mime2ext crate, less code for us to maintain.