Implement social relay functionality

* .well-known/social-relay - to serve subscription preferences to relays
* Workers.deferred_dispatch relay carbon copy functionality for outbound sending

See discussion here: https://www.loomio.org/d/9vpoe0UR/public-post-federation#comment-730911 and spec here: https://wiki.diasporafoundation.org/Relay_servers_for_public_posts

app/controllers/social_relay_controller.rb

@@ -0,0 +1,7 @@
+class SocialRelayController < ApplicationController
+  respond_to :json
+
+  def well_known
+    render json: SocialRelayPresenter.new
+  end
+end

app/presenters/social_relay_presenter.rb

@@ -0,0 +1,24 @@
+class SocialRelayPresenter
+  def as_json(*)
+    {
+      "subscribe" => AppConfig.relay.inbound.subscribe,
+      "scope"     => AppConfig.relay.inbound.scope,
+      "tags"      => tags
+    }
+  end
+
+  def tags
+    return [] unless AppConfig.relay.inbound.scope == "tags"
+    tags = AppConfig.relay.inbound.pod_tags.present? ? AppConfig.relay.inbound.pod_tags.split(",") : []
+    add_user_tags(tags)
+    tags.uniq
+  end
+
+  def add_user_tags(tags)
+    if AppConfig.relay.inbound.include_user_tags?
+      user_ids = User.halfyear_actives.pluck(:id)
+      tag_ids = TagFollowing.where(user: user_ids).select(:tag_id).distinct.pluck(:tag_id)
+      tags.concat ActsAsTaggableOn::Tag.where(id: tag_ids).pluck(:name)
+    end
+  end
+end

app/workers/deferred_dispatch.rb

@@ -10,14 +10,38 @@ module Workers
       user = User.find(user_id)
       object = object_class_name.constantize.find(object_id)
       opts = HashWithIndifferentAccess.new(opts)
-      opts[:services] = user.services.where(:type => opts.delete(:service_types))
-
-      if opts[:additional_subscribers].present?
-        opts[:additional_subscribers] = Person.where(:id => opts[:additional_subscribers])
-      end
+      opts[:services] = user.services.where(type: opts.delete(:service_types))
 
+      add_additional_subscribers(object, object_class_name, opts)
       Postzord::Dispatcher.build(user, object, opts).post
     rescue ActiveRecord::RecordNotFound # The target got deleted before the job was run
     end
+
+    def add_additional_subscribers(object, object_class_name, opts)
+      if AppConfig.relay.outbound.send? &&
+         object_class_name == "StatusMessage" &&
+         object.respond_to?(:public?) && object.public?
+        handle_relay(opts)
+      end
+
+      if opts[:additional_subscribers].present?
+        opts[:additional_subscribers] = Person.where(id: opts[:additional_subscribers])
+      end
+    end
+
+    def handle_relay(opts)
+      relay_person = Person.find_by diaspora_handle: AppConfig.relay.outbound.handle.to_s
+      if relay_person
+        add_person_to_subscribers(opts, relay_person)
+      else
+        # Skip this message for relay and just queue a webfinger fetch for the relay handle
+        Workers::FetchWebfinger.perform_async(AppConfig.relay.outbound.handle)
+      end
+    end
+
+    def add_person_to_subscribers(opts, person)
+      opts[:additional_subscribers] ||= []
+      opts[:additional_subscribers] << person.id
+    end
   end
 end

config/defaults.yml

@@ -193,6 +193,15 @@ defaults:
   admins:
     account:
     podmin_email:
+  relay:
+    outbound:
+      send: false
+      handle: 'relay@relay.iliketoast.net'
+    inbound:
+      subscribe: false
+      scope: tags
+      include_user_tags: false
+      pod_tags:
   # List valid environment variables
   redistogo_url:
 

config/diaspora.yml.example

@@ -679,6 +679,38 @@ configuration: ## Section
     ## E-mail address to contact the administrator.
     #podmin_email: 'podmin@example.org'
 
+  ## Settings related to relays
+  relay: ## Section
+
+    ## Relays are applications that exist to push public posts around to
+    ## pods which want to subscribe to them but would not otherwise
+    ## receive them due to not having direct contact with the remote pods.
+    ##
+    ## See more regarding relays: https://wiki.diasporafoundation.org/Relay_servers_for_public_posts
+
+    outbound: ## Section
+      ## Enable this setting to send out public posts from this pod to a relay
+      #send: false
+      ## Change default remote relay handle used for sending out here
+      #handle: 'relay@relay.iliketoast.net'
+
+    inbound: ## Section
+      ## Enable this to receive public posts from relays
+      #subscribe: false
+
+      ## Scope is either 'all' or 'tags' (default).
+      ## - 'all', means this pod wants to receive all public posts from a relay
+      ## - 'tags', means this pod wants only posts tagged with certain tags
+      #scope: tags
+
+      ## If scope is 'tags', should we include tags that users on this pod follow?
+      ## These are added in addition to 'pod_tags', if set.
+      #include_user_tags: false
+
+      ## If scope is 'tags', a comma separated list of tags here can be set.
+      ## For example "linux,diaspora", to receive posts related to these tags
+      #pod_tags:
+
 ## Here you can override settings defined above if you need
 ## to have them different in different environments.
 production: ## Section

config/routes.rb

@@ -244,6 +244,9 @@ Diaspora::Application.routes.draw do
     get 'terms' => 'terms#index'
   end
 
+  # Relay
+  get ".well-known/x-social-relay" => "social_relay#well_known"
+
   # Startpage
   root :to => 'home#show'
 end

spec/controllers/social_relay_controller_spec.rb

@@ -0,0 +1,16 @@
+require "spec_helper"
+
+describe SocialRelayController, type: :controller do
+  describe "#well_known" do
+    it "responds to format json" do
+      get :well_known, format: "json"
+      expect(response.code).to eq("200")
+    end
+
+    it "contains json" do
+      get :well_known, format: "json"
+      json = JSON.parse(response.body)
+      expect(json["scope"]).to be_present
+    end
+  end
+end

spec/presenters/social_relay_presenter_spec.rb

@@ -0,0 +1,122 @@
+require "spec_helper"
+
+describe SocialRelayPresenter do
+  before do
+    @presenter = SocialRelayPresenter.new
+  end
+
+  describe "#as_json" do
+    it "works" do
+      expect(@presenter.as_json).to be_present
+      expect(@presenter.as_json).to be_a Hash
+    end
+  end
+
+  describe "#social relay well-known contents" do
+    describe "defaults" do
+      it "provides valid detault data" do
+        expect(@presenter.as_json).to eq(
+          "subscribe" => false,
+          "scope"     => "tags",
+          "tags"      => []
+        )
+      end
+    end
+
+    describe "pod tags" do
+      before do
+        AppConfig.relay.inbound.pod_tags = "foo,bar"
+        AppConfig.relay.inbound.include_user_tags = false
+      end
+
+      it "provides pod tags" do
+        expect(@presenter.as_json).to eq(
+          "subscribe" => false,
+          "scope"     => "tags",
+          "tags"      => ["foo", "bar"]
+        )
+      end
+    end
+
+    describe "user tags" do
+      before do
+        AppConfig.relay.inbound.pod_tags = ""
+        AppConfig.relay.inbound.include_user_tags = true
+        ceetag = FactoryGirl.create(:tag, name: "cee")
+        lootag = FactoryGirl.create(:tag, name: "loo")
+        FactoryGirl.create(:tag_following, user: alice, tag: ceetag)
+        FactoryGirl.create(:tag_following, user: alice, tag: lootag)
+        alice.last_seen = Time.now - 2.month
+        alice.save
+      end
+
+      it "provides user tags" do
+        expect(@presenter.as_json).to eq(
+          "subscribe" => false,
+          "scope"     => "tags",
+          "tags"      => ["cee", "loo"]
+        )
+      end
+    end
+
+    describe "pod tags combined with user tags" do
+      before do
+        AppConfig.relay.inbound.pod_tags = "foo,bar"
+        AppConfig.relay.inbound.include_user_tags = true
+        ceetag = FactoryGirl.create(:tag, name: "cee")
+        lootag = FactoryGirl.create(:tag, name: "loo")
+        FactoryGirl.create(:tag_following, user: alice, tag: ceetag)
+        FactoryGirl.create(:tag_following, user: alice, tag: lootag)
+        alice.last_seen = Time.now - 2.month
+        alice.save
+      end
+
+      it "provides combined pod and user tags" do
+        expect(@presenter.as_json).to eq(
+          "subscribe" => false,
+          "scope"     => "tags",
+          "tags"      => ["foo", "bar", "cee", "loo"]
+        )
+      end
+    end
+
+    describe "user tags for inactive user" do
+      before do
+        AppConfig.relay.inbound.pod_tags = ""
+        AppConfig.relay.inbound.include_user_tags = true
+        ceetag = FactoryGirl.create(:tag, name: "cee")
+        lootag = FactoryGirl.create(:tag, name: "loo")
+        FactoryGirl.create(:tag_following, user: alice, tag: ceetag)
+        FactoryGirl.create(:tag_following, user: alice, tag: lootag)
+        alice.last_seen = Time.now - 8.month
+        alice.save
+      end
+
+      it "ignores user tags" do
+        expect(@presenter.as_json).to eq(
+          "subscribe" => false,
+          "scope"     => "tags",
+          "tags"      => []
+        )
+      end
+    end
+
+    describe "when scope is all" do
+      before do
+        AppConfig.relay.inbound.scope = "all"
+        AppConfig.relay.inbound.pod_tags = "foo,bar"
+        AppConfig.relay.inbound.include_user_tags = true
+        ceetag = FactoryGirl.create(:tag, name: "cee")
+        FactoryGirl.create(:tag_following, user: alice, tag: ceetag)
+      end
+
+      it "provides empty tags list" do
+        expect(@presenter.as_json).to eq(
+          "subscribe" => false,
+          "scope"     => "all",
+          "tags"      => []
+        )
+      end
+    end
+  end
+end

spec/workers/deferred_dispatch_spec.rb

@@ -3,7 +3,36 @@ require 'spec_helper'
 describe Workers::DeferredDispatch do
   it "handles non existing records gracefully" do
     expect {
-      described_class.new.perform(alice.id, 'Comment', 0, {})
+      described_class.new.perform(alice.id, "Comment", 0, {})
     }.to_not raise_error
   end
+
+  describe "#social relay functionality" do
+    let(:message) { FactoryGirl.create(:status_message, author: alice.person, public: true) }
+    before do
+      AppConfig.relay.outbound.send = true
+    end
+
+    it "triggers fetch of relay handle" do
+      allow(Person).to receive(:find_by).and_return(nil)
+
+      expect(Workers::FetchWebfinger).to receive(:perform_async)
+
+      described_class.new.perform(alice.id, "StatusMessage", message.id, {})
+    end
+
+    it "triggers post to relay" do
+      relay_person = FactoryGirl.create(:person, diaspora_handle: AppConfig.relay.outbound.handle)
+      opts = {"additional_subscribers" => [relay_person], "services" => []}
+      allow(Person).to receive(:find_by).and_return(relay_person)
+      postzord = double
+      allow(Postzord::Dispatcher).to receive(:build).with(any_args).and_return(postzord)
+      allow(postzord).to receive(:post)
+      allow(Person).to receive(:where).and_return([relay_person])
+
+      expect(Postzord::Dispatcher).to receive(:build).with(alice, message, opts)
+
+      described_class.new.perform(alice.id, "StatusMessage", message.id, {})
+    end
+  end
 end