lemmy/server/src/webfinger.rs

use crate::db::community::Community;
use crate::db::establish_connection;
use crate::Settings;
use actix_web::body::Body;
use actix_web::web::Query;
use actix_web::HttpResponse;
use regex::Regex;
use serde::Deserialize;
use serde_json::json;

#[derive(Deserialize)]
pub struct Params {
  resource: String,
}

lazy_static! {
  static ref WEBFINGER_COMMUNITY_REGEX: Regex = Regex::new(&format!(
    "^group:([a-z0-9_]{{3, 20}})@{}$",
    Settings::get().hostname
  ))
  .unwrap();
}

/// Responds to webfinger requests of the following format. There isn't any real documentation for
/// this, but it described in this blog post:
/// https://mastodon.social/.well-known/webfinger?resource=acct:gargron@mastodon.social
///
/// You can also view the webfinger response that Mastodon sends:
/// https://radical.town/.well-known/webfinger?resource=acct:felix@radical.town
pub fn get_webfinger_response(info: Query<Params>) -> HttpResponse<Body> {
  let regex_parsed = WEBFINGER_COMMUNITY_REGEX
    .captures(&info.resource)
    .map(|c| c.get(1));
  // TODO: replace this with .flatten() once we are running rust 1.40
  let regex_parsed_flattened = match regex_parsed {
    Some(s) => s,
    None => None,
  };
  let community_name = match regex_parsed_flattened {
    Some(c) => c.as_str(),
    None => return HttpResponse::NotFound().finish(),
  };

  // Make sure the requested community exists.
  let conn = establish_connection();
  let community = match Community::read_from_name(&conn, community_name.to_string()) {
    Ok(o) => o,
    Err(_) => return HttpResponse::NotFound().finish(),
  };

  let community_url = community.get_url();

  let json = json!({
    "subject": info.resource,
    "aliases": [
      community_url,
    ],
    "links": [
      {
        "rel": "http://webfinger.net/rel/profile-page",
        "type": "text/html",
        "href": community_url
      },
      {
        "rel": "self",
        "type": "application/activity+json",
        // Yes this is correct, this link doesn't include the `.json` extension
        "href": community_url
      }
      // TODO: this also needs to return the subscribe link once that's implemented
      //{
      //  "rel": "http://ostatus.org/schema/1.0/subscribe",
      //  "template": "https://my_instance.com/authorize_interaction?uri={uri}"
      //}
    ]
  });
  HttpResponse::Ok()
    .content_type("application/activity+json")
    .body(json.to_string())
}