sign json ld fetches

app/controllers/api/v1/json_ld_controller.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "faraday"
+require "uri"
 
 class Api::V1::JsonLdController < Api::BaseController
   include ActionController::Live
@@ -9,6 +10,40 @@ class Api::V1::JsonLdController < Api::BaseController
     render json: { error: e.to_s }, status: 422
   end
 
+  before_action :require_user!
+
+  REQUEST_TARGET = '(request-target)'
+
+  def signature(headers)
+    account = Account.representative
+
+    key_id = ActivityPub::TagManager.instance.key_uri_for(account)
+    algorithm = 'rsa-sha256'
+    signed_string = headers.map { |key, value| "#{key.downcase}: #{value}" }.join("\n")
+    signature = Base64.strict_encode64(account.keypair.sign(OpenSSL::Digest.new('SHA256'), signed_string))
+
+    "keyId=\"#{key_id}\",algorithm=\"#{algorithm}\",headers=\"#{headers.keys.join(' ').downcase}\",signature=\"#{signature}\""
+  end
+
+  def signed_headers(url_string)
+    if url_string.include?(".well-known")
+      return {'Accept': 'application/jrd+json'}
+    end
+
+    url = URI.parse(url_string)
+    tmp_headers = {
+      'Date': Time.now.utc.httpdate,
+      'Host': url.host,
+      'Accept': 'application/activity+json, application/ld+json; profile="https://www.w3.org/ns/activitystreams"',
+    }
+    tmp_headers[REQUEST_TARGET] = "get #{url_string.delete_prefix("#{url.scheme}://#{url.host}")}"
+    additional_headers = {
+      'Signature': signature(tmp_headers),
+      'User-Agent': Mastodon::Version.user_agent,
+    }
+    tmp_headers.merge(additional_headers).except(REQUEST_TARGET)
+  end
+
   def show
     url = params[:url]
 
@@ -17,13 +52,12 @@ class Api::V1::JsonLdController < Api::BaseController
     Thread.new {
       begin
         conn = Faraday::Connection.new
-        conn.options.timeout = 5
 
-        api_response = conn.get(url, nil, {'Accept' => 'application/ld+json; profile="https://www.w3.org/ns/activitystreams", application/jrd+json'})
+        api_response = conn.get(url, nil, signed_headers(url))
 
         max_redirects = 5
         while api_response.status == 301 || api_response.status == 302 and max_redirects > 0 do
-          api_response = conn.get(api_response.headers['Location'], nil, {'Accept' => 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'})
+          api_response = conn.get(api_response.headers['Location'], nil, signed_headers(api_response.headers['Location']))
           max_redirects -= 1
         end
 

app/views/shared/_og.html.haml

@@ -1,14 +1,14 @@
 - thumbnail     = @instance_presenter.thumbnail
-- description ||= @instance_presenter.description.presence || strip_tags(t('about.about_mastodon_html'))
+- description = 'Learn ActivityPub interactively, by seeing protocol interactions visualized in real time'
 
 %meta{ name: 'description', content: description }/
 
-= opengraph 'og:site_name', t('about.hosted_on', domain: site_hostname)
+= opengraph 'og:site_name', 'ActivityPub Academy - A learning resource for ActivityPub'
 = opengraph 'og:url', url_for(only_path: false)
 = opengraph 'og:type', 'website'
-= opengraph 'og:title', @instance_presenter.title
+= opengraph 'og:title', 'ActivityPub Academy'
 = opengraph 'og:description', description
-= opengraph 'og:image', full_asset_url(thumbnail&.file&.url(:'@1x') || asset_pack_path('media/images/preview.png', protocol: :request))
+= opengraph 'og:image', full_asset_url(thumbnail&.file&.url(:'@1x') || asset_pack_path('media/images/academy-mascot.webp', protocol: :request))
-= opengraph 'og:image:width', thumbnail ? thumbnail.meta['width'] : '1200'
+= opengraph 'og:image:width', thumbnail ? thumbnail.meta['width'] : '500'
-= opengraph 'og:image:height', thumbnail ? thumbnail.meta['height'] : '630'
+= opengraph 'og:image:height', thumbnail ? thumbnail.meta['height'] : '573'
 = opengraph 'twitter:card', 'summary_large_image'

dist/nginx.conf

@@ -114,6 +114,27 @@ server {
     tcp_nodelay on;
   }
 
+  location ^~ /api/v1/json_ld {
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto https;
+    proxy_set_header Proxy "";
+    proxy_pass_header Server;
+
+    proxy_pass http://backend;
+    proxy_redirect off;
+    proxy_http_version 1.1;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection '';
+
+    proxy_cache off;
+    proxy_buffering off;
+    chunked_transfer_encoding off;
+
+    tcp_nodelay on;
+  }
+
   location ^~ /api/v1/activity_log {
     proxy_set_header Host $host;
     proxy_set_header X-Real-IP $remote_addr;