Pixiv bridge: Support login

[guldor12]

Is your feature request related to a problem? Please describe.
Pixiv doesn't display R-18 and R-18G works to unregistered users.
Examples:
User with R-18 works (some non-R-18 works are also hidden)
User with R-18G (gore) works

Describe the solution you'd like
Login support should be added/documented like with Instagram/Twitter. It may be possible to copy cookies like with the Furaffinity bridge, but I haven't looked into it much.

Describe alternatives you've considered
I'm not aware of any way to access R-18+ works without an account.

Additional context
This would also be a prerequisite for adding a bridge for https://www.pixiv.net/bookmark_new_illust.php which displays recent works of your followed users. That endpoint would also be nice for users with lots of follows since it would avoid hammering pixiv's servers.

[yamanq]

If this is added, it should be as a checkbox, "Show R-18 works"

[dvikan]

As discussed earlier, this goes against the nature of the project. But I can accept placing this bridge in e.g. ./contrib folder. Or add a configuration value that is used if present. I guess im okay with a form field with the user and pass but I don't like it.

[guldor12]

Configuration values for API keys were what I was thinking of, like the Twitter bridge. And now that I think about it, R-18/R-18G is a toggle in account settings, not cookies, so non-logged in bridges wouldn't need a useless check box added. Unfortunately the https://www.pixiv.net/bookmark_new_illust.php endpoint is only available for the logged in user, so maybe a bridge could be added to the ./contrib folder to support it.

Also, I looked into it more and getting a Pixiv API key is a huge hassle, but if you require the user to input their API key to a static config file, you can have them follow these instructions and paste the refresh token where RSS-Bridge can find it. RSS-Bridge would then need to fetch and cache a new refresh and auth token and their expiration time and repeat whenever they expire. One problem with this is that the refresh token in the config would no longer refer to any valid token, but maybe RSS-Bridge could just associate this old token with its current state and refresh using it only when it changes.

[mruac]

@guldor12 I'm looking into this, why not use the PHPSESSID cookie instead? I'm not sure if pixiv renews the cookie when it is about to expire, but the bridge can certainly check and update the cookie in the cache as it changed.

[mruac]

I'm also not sure why this bridge caches the images yet - I'm going to see if using no-referrer on the images will work.

edit: oh what fun they need a referrer to view the image.

[mruac]

Difference between using cookie and oauth are different endpoints / and datasets to work with, but for compatibility reasons I'll work with cookies instead.

Both resulting links to images still require a referrer set to Pixiv, so caching / proxying the images are still required.

[mruac]

Good site to proxy images from. They also have a handy nginx or Cloudflare worker profile to use for self-hosters.
https://pixiv.cat

[mruac]

@guldor12 R-18 works are now supported if you follow the bridge specific documentation when hosting rss-bridge yourself.

Re: the bridge for https://www.pixiv.net/bookmark_new_illust.php You are still able to follow each user individually without needing to create a new (or edit this) bridge, but you are welcome to keep this issue open if someone is willing to add support.