Refactor ActivityPub handling to prepare for non-Account actors (#19212)

* Move ActivityPub::FetchRemoteAccountService to ActivityPub::FetchRemoteActorService

ActivityPub::FetchRemoteAccountService is kept as a wrapper for when the actor is
specifically required to be an Account

* Refactor SignatureVerification to allow non-Account actors

* fixup! Move ActivityPub::FetchRemoteAccountService to ActivityPub::FetchRemoteActorService

* Refactor ActivityPub::FetchRemoteKeyService to potentially return non-Account actors

* Refactor inbound ActivityPub payload processing to accept non-Account actors

* Refactor inbound ActivityPub processing to accept activities relayed through non-Account

* Refactor how Account key URIs are built

* Refactor Request and drop unused key_id_format parameter

* Rename ActivityPub::Dereferencer `signature_account` to `signature_actor`

1 files changed, 180 insertions, 0 deletions

diff --git a/spec/services/activitypub/fetch_remote_actor_service_spec.rb b/spec/services/activitypub/fetch_remote_actor_service_spec.rb
new file mode 100644
index 000000000..20117c66d
--- /dev/null
+++ b/spec/services/activitypub/fetch_remote_actor_service_spec.rb
@@ -0,0 +1,180 @@
+require 'rails_helper'
+
+RSpec.describe ActivityPub::FetchRemoteActorService, type: :service do
+  subject { ActivityPub::FetchRemoteActorService.new }
+
+  let!(:actor) do
+    {
+      '@context': 'https://www.w3.org/ns/activitystreams',
+      id: 'https://example.com/alice',
+      type: 'Person',
+      preferredUsername: 'alice',
+      name: 'Alice',
+      summary: 'Foo bar',
+      inbox: 'http://example.com/alice/inbox',
+    }
+  end
+
+  describe '#call' do
+    let(:account) { subject.call('https://example.com/alice', id: true) }
+
+    shared_examples 'sets profile data' do
+      it 'returns an account' do
+        expect(account).to be_an Account
+      end
+
+      it 'sets display name' do
+        expect(account.display_name).to eq 'Alice'
+      end
+
+      it 'sets note' do
+        expect(account.note).to eq 'Foo bar'
+      end
+
+      it 'sets URL' do
+        expect(account.url).to eq 'https://example.com/alice'
+      end
+    end
+
+    context 'when the account does not have a inbox' do
+      let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice' }] } }
+
+      before do
+        actor[:inbox] = nil
+
+        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor))
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      end
+
+      it 'fetches resource' do
+        account
+        expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+      end
+
+      it 'looks up webfinger' do
+        account
+        expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to have_been_made.once
+      end
+
+      it 'returns nil' do
+        expect(account).to be_nil
+      end
+    end
+
+    context 'when URI and WebFinger share the same host' do
+      let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice' }] } }
+
+      before do
+        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor))
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      end
+
+      it 'fetches resource' do
+        account
+        expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+      end
+
+      it 'looks up webfinger' do
+        account
+        expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to have_been_made.once
+      end
+
+      it 'sets username and domain from webfinger' do
+        expect(account.username).to eq 'alice'
+        expect(account.domain).to eq 'example.com'
+      end
+
+      include_examples 'sets profile data'
+    end
+
+    context 'when WebFinger presents different domain than URI' do
+      let!(:webfinger) { { subject: 'acct:alice@iscool.af', links: [{ rel: 'self', href: 'https://example.com/alice' }] } }
+
+      before do
+        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor))
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      end
+
+      it 'fetches resource' do
+        account
+        expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+      end
+
+      it 'looks up webfinger' do
+        account
+        expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to have_been_made.once
+      end
+
+      it 'looks up "redirected" webfinger' do
+        account
+        expect(a_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af')).to have_been_made.once
+      end
+
+      it 'sets username and domain from final webfinger' do
+        expect(account.username).to eq 'alice'
+        expect(account.domain).to eq 'iscool.af'
+      end
+
+      include_examples 'sets profile data'
+    end
+
+    context 'when WebFinger returns a different URI' do
+      let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/bob' }] } }
+
+      before do
+        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor))
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      end
+
+      it 'fetches resource' do
+        account
+        expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+      end
+
+      it 'looks up webfinger' do
+        account
+        expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to have_been_made.once
+      end
+
+      it 'does not create account' do
+        expect(account).to be_nil
+      end
+    end
+
+    context 'when WebFinger returns a different URI after a redirection' do
+      let!(:webfinger) { { subject: 'acct:alice@iscool.af', links: [{ rel: 'self', href: 'https://example.com/bob' }] } }
+
+      before do
+        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor))
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      end
+
+      it 'fetches resource' do
+        account
+        expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+      end
+
+      it 'looks up webfinger' do
+        account
+        expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to have_been_made.once
+      end
+
+      it 'looks up "redirected" webfinger' do
+        account
+        expect(a_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af')).to have_been_made.once
+      end
+
+      it 'does not create account' do
+        expect(account).to be_nil
+      end
+    end
+
+    context 'with wrong id' do
+      it 'does not create account' do
+        expect(subject.call('https://fake.address/@foo', prefetched_body: Oj.dump(actor))).to be_nil
+      end
+    end
+  end
+end