create entity fetcher for public entities

lib/diaspora_federation/federation.rb

@@ -4,5 +4,6 @@ module DiasporaFederation
   end
 end
 
+require "diaspora_federation/federation/fetcher"
 require "diaspora_federation/federation/receiver"
 require "diaspora_federation/federation/sender"

lib/diaspora_federation/federation/fetcher.rb

@@ -0,0 +1,26 @@
+module DiasporaFederation
+  module Federation
+    # this module is for fetching entities from other pods
+    module Fetcher
+      # fetches a public entity from a remote pod
+      # @param [String] author the diaspora ID of the author of the entity
+      # @param [Symbol, String] entity_type snake_case version of the entity class
+      # @param [String] guid guid of the entity to fetch
+      def self.fetch_public(author, entity_type, guid)
+        url = DiasporaFederation.callbacks.trigger(:fetch_person_url_to, author, "/fetch/#{entity_type}/#{guid}")
+        response = DiasporaFederation::Fetcher.get(url)
+        raise "Failed to fetch #{url}: #{response.status}" unless response.success?
+
+        magic_env = Nokogiri::XML::Document.parse(response.body).root
+        entity = Salmon::MagicEnvelope.unenvelop(magic_env)
+        DiasporaFederation.callbacks.trigger(:save_entity_after_receive, entity)
+      rescue => e
+        raise NotFetchable, "Failed to fetch #{entity_type}:#{guid} from #{author}: #{e.class}: #{e.message}"
+      end
+
+      # Raised, if the entity is not fetchable
+      class NotFetchable < RuntimeError
+      end
+    end
+  end
+end

spec/lib/diaspora_federation/federation/fetcher_spec.rb

@@ -0,0 +1,76 @@
+module DiasporaFederation
+  describe Federation::Fetcher do
+    let(:post) { FactoryGirl.build(:status_message_entity, public: true) }
+    let(:post_magic_env) { Salmon::MagicEnvelope.new(post).envelop(alice.private_key, post.author).to_xml }
+
+    describe ".fetch_public" do
+      it "fetches a public post" do
+        stub_request(:get, "https://example.org/fetch/post/#{post.guid}")
+          .to_return(status: 200, body: post_magic_env)
+
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :fetch_person_url_to, post.author, "/fetch/post/#{post.guid}"
+        ).and_return("https://example.org/fetch/post/#{post.guid}")
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :fetch_public_key_by_diaspora_id, post.author
+        ).and_return(alice.public_key)
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :save_entity_after_receive, kind_of(Entities::StatusMessage)
+        ) do |_, entity|
+          expect(entity.guid).to eq(post.guid)
+          expect(entity.author).to eq(post.author)
+          expect(entity.raw_message).to eq(post.raw_message)
+          expect(entity.public).to eq("true")
+        end
+
+        Federation::Fetcher.fetch_public(post.author, :post, post.guid)
+      end
+
+      it "follows redirects" do
+        stub_request(:get, "https://example.org/fetch/post/#{post.guid}")
+          .to_return(status: 302, headers: {"Location" => "https://example.com/fetch/post/#{post.guid}"})
+        stub_request(:get, "https://example.com/fetch/post/#{post.guid}")
+          .to_return(status: 200, body: post_magic_env)
+
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :fetch_person_url_to, post.author, "/fetch/post/#{post.guid}"
+        ).and_return("https://example.org/fetch/post/#{post.guid}")
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :fetch_public_key_by_diaspora_id, post.author
+        ).and_return(alice.public_key)
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :save_entity_after_receive, kind_of(Entities::StatusMessage)
+        )
+
+        Federation::Fetcher.fetch_public(post.author, :post, post.guid)
+      end
+
+      it "raises NotFetchable if post not found (private)" do
+        stub_request(:get, "https://example.org/fetch/post/#{post.guid}")
+          .to_return(status: 404)
+
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :fetch_person_url_to, post.author, "/fetch/post/#{post.guid}"
+        ).and_return("https://example.org/fetch/post/#{post.guid}")
+
+        expect {
+          Federation::Fetcher.fetch_public(post.author, :post, post.guid)
+        }.to raise_error Federation::Fetcher::NotFetchable
+      end
+
+      it "raises NotFetchable if connection refused" do
+        expect(DiasporaFederation::Fetcher).to receive(:get).with(
+          "https://example.org/fetch/post/#{post.guid}"
+        ).and_raise(Faraday::ConnectionFailed, "Couldn't connect to server")
+
+        expect(DiasporaFederation.callbacks).to receive(:trigger).with(
+          :fetch_person_url_to, post.author, "/fetch/post/#{post.guid}"
+        ).and_return("https://example.org/fetch/post/#{post.guid}")
+
+        expect {
+          Federation::Fetcher.fetch_public(post.author, :post, post.guid)
+        }.to raise_error Federation::Fetcher::NotFetchable
+      end
+    end
+  end
+end

spec/support/shared_entity_specs.rb

@@ -85,10 +85,8 @@ shared_examples "a relayable Entity" do
       author_signature = xml.at_xpath("post/*[1]/author_signature").text
       parent_author_signature = xml.at_xpath("post/*[1]/parent_author_signature").text
 
-      alice_public_key = OpenSSL::PKey::RSA.new(alice.serialized_public_key)
-      bob_public_key = OpenSSL::PKey::RSA.new(bob.serialized_public_key)
-      expect(verify_signature(alice_public_key, author_signature, signed_string)).to be_truthy
-      expect(verify_signature(bob_public_key, parent_author_signature, signed_string)).to be_truthy
+      expect(verify_signature(alice.public_key, author_signature, signed_string)).to be_truthy
+      expect(verify_signature(bob.public_key, parent_author_signature, signed_string)).to be_truthy
     end
   end
 end

test/dummy/app/models/person.rb

@@ -1,6 +1,9 @@
 class Person < ActiveRecord::Base
   include ::Diaspora::Guid
 
+  def private_key; OpenSSL::PKey::RSA.new(serialized_private_key) end
+  def public_key;  OpenSSL::PKey::RSA.new(serialized_public_key) end
+
   def alias_url;     "#{url}people/#{guid}" end
   def hcard_url;     "#{url}hcard/users/#{guid}" end
   def profile_url;   "#{url}u/#{nickname}" end