This release continues my focus on security instead of new features. As I wrote earlier this week, I rebuilt the template framework Ktistec uses with type safety as a central principle. What does that mean?

Imagine that you have an instance of a String that holds federated data. Where can you safely render that in a browser, and what operations (sanitization, escaping, etc.) do you need to do first?

The only way to answer that is to look carefully at the lineage of that data: where it came from, how it was stored, how it was transformed, and where it's rendered. A name holds text; an href or src attribute holds a URL. If you want to render a name inside an HTML element you should HTML escape it. You should escape href and src, too, but the escaping rules for URLs are slightly different from the HTML rules. It's easy to make mistakes.

Ktistec uses four "safe" types to express the contracts:

SafeHTML: A String wrapper marking HTML markup safe to emit raw into HTML data slots (text content, between tags).

SafeAttrValue: A String wrapper marking a value safe to emit raw inside a double-quoted HTML attribute (attr="..."), other than URL or event-handler slots.

SafeURI: A String wrapper marking a URL safe to emit raw into a URL attribute slot (href, src, action, etc.).

SafeJSON: A String wrapper marking JSON output safe to emit raw into the body of a <script type="application/json"> block.

Using the wrong type at a call site is either a compile-time error, or it triggers automatic sanitization of the underlying string value.

Here's the full changelog:

Added

• String safety framework with typed "safe" strings.
• New Slang template engine with compile-time safety checks.
• Vendored WebFinger and HostMeta client shards.

Fixed

• Prevent delivery to unknown IRIs.
• Narrow Like/Dislike addressing to the liked object's author.

I have at least one more cleanup pass to do, and then I'll turn my attention back to the Mastodon-compatible API and a few features I've been looking forward to—like scheduled posts.

#ktistec #crystallang #activitypub #fediverse

One of the nice benefits of working on an open source project is that you can scratch an itch for as long as you feel like scratching. A game I like to play while scratching is called "what invalid states can I make unrepresentable" using the type system.

ktistec uses a template language for views and partials. In its original form, it allowed a programmer to use = to escape an untrusted value or == to render it unescaped. You might want to escape an actor's name property because a name should never contain HTML but you might want to sanitize an object's content property and then render it without escaping because the body of a post can contain HTML.

The problem is you have to remember the rules and never make a mistake. If you accidentally type == actor.name you've just created a potential cross-site scripting (XSS) vulnerability!

ktistec's template language now makes it much more difficult to screw up.

There's now only = syntax and by default it escapes everything. The only way to get it to emit a string without escaping is to wrap it in SafeHTML. The sanitize helper sanitizes HTML and then wraps it for you. Other common helpers (e.g. path construction helpers) do the same.

Importantly, if you interpolate a safe value into a string, it is demoted back to a string and will be escaped unless it is explicitly wrapped again.

Unescaped HTML is still possible to construct, but it's now much harder to do so accidentally. You can't just concatenate some strings together—forgetting that one comes from an untrusted source—and render that as unescaped HTML.

#ktistec #crystallang

Release v3.3.7 of Ktistec fixes several bugs and introduces two enhancements.

Security is a focus in this release. Every gap in input sanitization or escaping is a potential vulnerability, and I've been systematically closing them. I am also carefully, and maybe conservatively, restricting things like supported URL schemes and uploaded file types.

The two enhancements improve compatibility with Mastodon-compatible clients. Mastodon's OAuth tokens don't expire, and Mastodon clients don't know how to handle tokens that do. Sliding expiration ensures that tokens in active use stay alive, while unused tokens eventually expire.

Here's the full changelog:

Added

• Sliding token expiration for OAuth2 access tokens.
• Mastodon-compatible API: /api/v1/accounts/update_credentials endpoint.

Fixed

• Prevent pinning of (and auto-unpin) private objects.
• Don't save a quote if the quoted actor cannot be dereferenced.
• Fix rendering of federated actor profile attachment values.
• Remove href attributes with unsafe schemes from sanitized HTML.
• Escape interpolated values in view helpers and the actor icon streaming refresh.
• Restrict upload extensions and serve uploads with X-Content-Type-Options: nosniff.
• Escape publicKey and scrub Tag.href.
• Sanitizer no longer permits single-quote attribute injection.
• Ensure bearer-token sessions cannot reach the web UI.
• Require client authentication on the OAuth token endpoint.

I'm working on performance improvements for the next release. A rewrite of the Slang template library looks like it will cut both build time and executable size by around 10%!

📡 Stay tuned!

#ktistec #crystallang #activitypub #fediverse

I’m working on handling OAuth token expiry as part of #ktistec Mastodon API support. Is my understanding that Mastodon issues OAuth tokens with no expiration correct?!?

This release is a maintenance update: a few bug fixes, a security mitigation worth paying attention to, and some performance improvements for users on slow connections.

It's worth updating to pick up the SSRF (Server-Side Request Forgery) mitigation.

Fixed

• Prevent SSRF when dereferencing externally supplied IRIs.
• Timeline entry no longer becomes stale when an announce is undone.
• Correctly represent boosted posts on the home timeline in API clients.

Changed

• Defer downloading of script files.
• Defer loading of image, video, and audio attachments.
• Move poll vote notification for voters into the outbox processor.

#ktistec #crystallang #activitypub #fediverse

The Mastodon-compatible API is at a stable stopping point, so I have removed the gating with_mastodon_api build flag and made it generally available.

I use the API daily via a couple different client apps. What works, works. There are known limitations, most of them rooted in architectural differences between Mastodon and Ktistec. For example, Mastodon and Ktistec manage media differently. In Ktistec, there is no simple way to upload and manage media apart from creating a post. That difference will take some work to bridge.

Here's the full changelog for this release:

Added

• Mastodon-compatible API endpoints:
  • /api/v1/accounts
  • /api/v1/accounts/lookup
  • /api/v1/accounts/:id
  • /api/v1/accounts/:id/statuses
  • /api/v1/accounts/:id/following
  • /api/v1/accounts/:id/followers
  • /api/v1/accounts/relationships
  • /api/v1/follow_requests
  • /api/v1/polls/:id/votes
  • /api/v1/preferences

Fixed

• Correctly resolve keyId from Signature header for inbox verification.

Changed

• Support both offset and cursor-based pagination in JSON collections.
• Switch following/followers pages to cursor-based pagination.

Credit goes to this thread for inspiring me to review my signature verification. There is now one more correct implementation. 😉

The next release will focus on cleaning up the internals. Ktistec is just under 100,000 lines of code, 307 source files, and 195 spec files (7030 tests). With one maintainer, the only way to stay sane is by ruthlessly refactoring and paying down the debt!

#ktistec #crystallang #activitypub #fediverse

mastodon API support in Ktistec is almost an MVP. building it has involved an unexpected number of side quests. but some of them have been worthwhile excursions—Ktistec will be getting cursor based pagination (a popular request) and offset/limit pagination will be going away.

#ktistec

Release v3.3.4 of Ktistec is available.

This release adds Mastodon-compatible client support for publishing posts. Just like the previous release, however, all Mastodon API support is behind a build flag (-Dwith_mastodon_api). It's still experimental, so opt in only if you're happy to work with rough edges.

Beyond that, I focused on cleanup and refactoring throughout the codebase. Here's the full changelog:

Added

• Cursor-based pagination on actor timeline and everything pages.
• Mastodon-compatible API: /api/v1/statuses endpoint for status posting.
• Mastodon-compatible API: /api/v1/timelines/public endpoint.

Fixed

• Autosave focus handling. Fixes problems introduced in v3.3.3.
• Prevent blur from creating a draft post when publishing a post.

Changed

• Integrate X-Ray Mode colors into the theming system.
• Improve CI: add npm audit, test, and caching.
• Use npm ci in Dockerfile for reproducible builds.
• Remove very old compiler bug work-around.

🏋️ Mastodon API support is coming along—more in the next release!

#ktistec #crystallang #activitypub #fediverse

test post from tusker via Mastodon-compatible API… #ktistec

I have started work on a Mastodon-compatible API layer intended to support the many Mastodon front-ends available. It is incomplete and requires an explicit build flag to enable, but what's there (the main timeline) already works with the official Mastodon app, Tusky, and Phanpy.

Here's the full changelog:

Fixed

• Editor focus now stays in the editor after the first draft is saved. (fixes #139)
• Filter settings instructions. (fixes #135)

Changed

• Improved consistency of mini button colors.

As always, check out the full diff for the complete details.

#ktistec #crystallang #activitypub #fediverse