[feature] Allow delivery to sharedInboxes where possible (#847)

* update Activity

* add instance-deliver-to-shared-inboxes setting

* update activity version again

* add SharedInboxURI field to accounts

* serdes for endpoints/sharedInbox

* deliver to sharedInbox if one is available

* update tests

* only assign shared inbox if shared domain

* look for shared inbox if currently nil

* go fmt

* finger to get params.RemoteAccountID if necessary

* make comments clearer

* compare dns more consistently

4 files changed, 75 insertions, 0 deletions

diff --git a/internal/typeutils/astointernal.go b/internal/typeutils/astointernal.go
index 7ec45335d..b69bb247e 100644
--- a/internal/typeutils/astointernal.go
+++ b/internal/typeutils/astointernal.go
@@ -23,6 +23,7 @@ import (
 	"errors"
 	"fmt"
 
+	"github.com/miekg/dns"
 	"github.com/superseriousbusiness/gotosocial/internal/ap"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
@@ -156,6 +157,19 @@ func (c *converter) ASRepresentationToAccount(ctx context.Context, accountable a
 		acct.InboxURI = accountable.GetActivityStreamsInbox().GetIRI().String()
 	}
 
+	// SharedInboxURI
+	if sharedInboxURI := ap.ExtractSharedInbox(accountable); sharedInboxURI != nil {
+		var sharedInbox string
+
+		// only trust shared inbox if it has at least two domains,
+		// from the right, in common with the domain of the account
+		if dns.CompareDomainName(acct.Domain, sharedInboxURI.Host) >= 2 {
+			sharedInbox = sharedInboxURI.String()
+		}
+
+		acct.SharedInboxURI = &sharedInbox
+	}
+
 	// OutboxURI
 	if accountable.GetActivityStreamsOutbox() != nil && accountable.GetActivityStreamsOutbox().GetIRI() != nil {
 		acct.OutboxURI = accountable.GetActivityStreamsOutbox().GetIRI().String()
diff --git a/internal/typeutils/astointernal_test.go b/internal/typeutils/astointernal_test.go
index 7024018d6..9273405e6 100644
--- a/internal/typeutils/astointernal_test.go
+++ b/internal/typeutils/astointernal_test.go
@@ -45,6 +45,7 @@ func (suite *ASToInternalTestSuite) TestParsePerson() {
 	suite.Equal("https://unknown-instance.com/users/brand_new_person/following", acct.FollowingURI)
 	suite.Equal("https://unknown-instance.com/users/brand_new_person/followers", acct.FollowersURI)
 	suite.Equal("https://unknown-instance.com/users/brand_new_person/inbox", acct.InboxURI)
+	suite.Nil(acct.SharedInboxURI)
 	suite.Equal("https://unknown-instance.com/users/brand_new_person/outbox", acct.OutboxURI)
 	suite.Equal("https://unknown-instance.com/users/brand_new_person/collections/featured", acct.FeaturedCollectionURI)
 	suite.Equal("brand_new_person", acct.Username)
@@ -56,6 +57,28 @@ func (suite *ASToInternalTestSuite) TestParsePerson() {
 	suite.False(*acct.Locked)
 }
 
+func (suite *ASToInternalTestSuite) TestParsePersonWithSharedInbox() {
+	testPerson := suite.testPeople["https://turnip.farm/users/turniplover6969"]
+
+	acct, err := suite.typeconverter.ASRepresentationToAccount(context.Background(), testPerson, "", false)
+	suite.NoError(err)
+
+	suite.Equal("https://turnip.farm/users/turniplover6969", acct.URI)
+	suite.Equal("https://turnip.farm/users/turniplover6969/following", acct.FollowingURI)
+	suite.Equal("https://turnip.farm/users/turniplover6969/followers", acct.FollowersURI)
+	suite.Equal("https://turnip.farm/users/turniplover6969/inbox", acct.InboxURI)
+	suite.Equal("https://turnip.farm/sharedInbox", *acct.SharedInboxURI)
+	suite.Equal("https://turnip.farm/users/turniplover6969/outbox", acct.OutboxURI)
+	suite.Equal("https://turnip.farm/users/turniplover6969/collections/featured", acct.FeaturedCollectionURI)
+	suite.Equal("turniplover6969", acct.Username)
+	suite.Equal("Turnip Lover 6969", acct.DisplayName)
+	suite.Equal("I just think they're neat", acct.Note)
+	suite.Equal("https://turnip.farm/@turniplover6969", acct.URL)
+	suite.True(*acct.Discoverable)
+	suite.Equal("https://turnip.farm/users/turniplover6969#main-key", acct.PublicKeyURI)
+	suite.False(*acct.Locked)
+}
+
 func (suite *ASToInternalTestSuite) TestParsePublicStatus() {
 	m := make(map[string]interface{})
 	err := json.Unmarshal([]byte(publicStatusActivityJson), &m)
@@ -109,6 +132,8 @@ func (suite *ASToInternalTestSuite) TestParseGargron() {
 	acct, err := suite.typeconverter.ASRepresentationToAccount(context.Background(), rep, "", false)
 	suite.NoError(err)
 
+	suite.Equal("https://mastodon.social/inbox", *acct.SharedInboxURI)
+
 	fmt.Printf("%+v", acct)
 	// TODO: write assertions here, rn we're just eyeballing the output
 }
diff --git a/internal/typeutils/internaltoas.go b/internal/typeutils/internaltoas.go
index 6d8a22cab..a678a970f 100644
--- a/internal/typeutils/internaltoas.go
+++ b/internal/typeutils/internaltoas.go
@@ -85,6 +85,21 @@ func (c *converter) AccountToAS(ctx context.Context, a *gtsmodel.Account) (vocab
 	inboxProp.SetIRI(inboxURI)
 	person.SetActivityStreamsInbox(inboxProp)
 
+	// shared inbox -- only add this if we know for sure it has one
+	if a.SharedInboxURI != nil && *a.SharedInboxURI != "" {
+		sharedInboxURI, err := url.Parse(*a.SharedInboxURI)
+		if err != nil {
+			return nil, err
+		}
+		endpointsProp := streams.NewActivityStreamsEndpointsProperty()
+		endpoints := streams.NewActivityStreamsEndpoints()
+		sharedInboxProp := streams.NewActivityStreamsSharedInboxProperty()
+		sharedInboxProp.SetIRI(sharedInboxURI)
+		endpoints.SetActivityStreamsSharedInbox(sharedInboxProp)
+		endpointsProp.AppendActivityStreamsEndpoints(endpoints)
+		person.SetActivityStreamsEndpoints(endpointsProp)
+	}
+
 	// outbox
 	// the activitypub outbox of this user for serving messages
 	outboxURI, err := url.Parse(a.OutboxURI)
diff --git a/internal/typeutils/internaltoas_test.go b/internal/typeutils/internaltoas_test.go
index b6da422b1..83e235113 100644
--- a/internal/typeutils/internaltoas_test.go
+++ b/internal/typeutils/internaltoas_test.go
@@ -52,6 +52,27 @@ func (suite *InternalToASTestSuite) TestAccountToAS() {
 	suite.Equal(`:true,"featured":"http://localhost:8080/users/the_mighty_zork/collections/featured","followers":"http://localhost:8080/users/the_mighty_zork/followers","following":"http://localhost:8080/users/the_mighty_zork/following","icon":{"mediaType":"image/jpeg","type":"Image","url":"http://localhost:8080/fileserver/01F8MH1H7YV1Z7D2C8K2730QBF/avatar/original/01F8MH58A357CV5K7R7TJMSH6S.jpeg"},"id":"http://localhost:8080/users/the_mighty_zork","image":{"mediaType":"image/jpeg","type":"Image","url":"http://localhost:8080/fileserver/01F8MH1H7YV1Z7D2C8K2730QBF/header/original/01PFPMWK2FF0D9WMHEJHR07C3Q.jpeg"},"inbox":"http://localhost:8080/users/the_mighty_zork/inbox","manuallyApprovesFollowers":false,"name":"original zork (he/they)","outbox":"http://localhost:8080/users/the_mighty_zork/outbox","preferredUsername":"the_mighty_zork","publicKey":{"id":"http://localhost:8080/users/the_mighty_zork/main-key","owner":"http://localhost:8080/users/the_mighty_zork","publicKeyPem":"-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwXTcOAvM1Jiw5Ffpk0qn\nr0cwbNvFe/5zQ+Tp7tumK/ZnT37o7X0FUEXrxNi+dkhmeJ0gsaiN+JQGNUewvpSk\nPIAXKvi908aSfCGjs7bGlJCJCuDuL5d6m7hZnP9rt9fJc70GElPpG0jc9fXwlz7T\nlsPb2ecatmG05Y4jPwdC+oN4MNCv9yQzEvCVMzl76EJaM602kIHC1CISn0rDFmYd\n9rSN7XPlNJw1F6PbpJ/BWQ+pXHKw3OEwNTETAUNYiVGnZU+B7a7bZC9f6/aPbJuV\nt8Qmg+UnDvW1Y8gmfHnxaWG2f5TDBvCHmcYtucIZPLQD4trAozC4ryqlmCWQNKbt\n0wIDAQAB\n-----END PUBLIC KEY-----\n"},"summary":"\u003cp\u003ehey yo this is my profile!\u003c/p\u003e","type":"Person","url":"http://localhost:8080/@the_mighty_zork"}`, trimmed)
 }
 
+func (suite *InternalToASTestSuite) TestAccountToASWithSharedInbox() {
+	testAccount := suite.testAccounts["local_account_1"] // take zork for this test
+	sharedInbox := "http://localhost:8080/sharedInbox"
+	testAccount.SharedInboxURI = &sharedInbox
+
+	asPerson, err := suite.typeconverter.AccountToAS(context.Background(), testAccount)
+	suite.NoError(err)
+
+	ser, err := streams.Serialize(asPerson)
+	suite.NoError(err)
+
+	bytes, err := json.Marshal(ser)
+	suite.NoError(err)
+
+	// trim off everything up to 'discoverable';
+	// this is necessary because the order of multiple 'context' entries is not determinate
+	trimmed := strings.Split(string(bytes), "\"discoverable\"")[1]
+
+	suite.Equal(`:true,"endpoints":{"sharedInbox":"http://localhost:8080/sharedInbox"},"featured":"http://localhost:8080/users/the_mighty_zork/collections/featured","followers":"http://localhost:8080/users/the_mighty_zork/followers","following":"http://localhost:8080/users/the_mighty_zork/following","icon":{"mediaType":"image/jpeg","type":"Image","url":"http://localhost:8080/fileserver/01F8MH1H7YV1Z7D2C8K2730QBF/avatar/original/01F8MH58A357CV5K7R7TJMSH6S.jpeg"},"id":"http://localhost:8080/users/the_mighty_zork","image":{"mediaType":"image/jpeg","type":"Image","url":"http://localhost:8080/fileserver/01F8MH1H7YV1Z7D2C8K2730QBF/header/original/01PFPMWK2FF0D9WMHEJHR07C3Q.jpeg"},"inbox":"http://localhost:8080/users/the_mighty_zork/inbox","manuallyApprovesFollowers":false,"name":"original zork (he/they)","outbox":"http://localhost:8080/users/the_mighty_zork/outbox","preferredUsername":"the_mighty_zork","publicKey":{"id":"http://localhost:8080/users/the_mighty_zork/main-key","owner":"http://localhost:8080/users/the_mighty_zork","publicKeyPem":"-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwXTcOAvM1Jiw5Ffpk0qn\nr0cwbNvFe/5zQ+Tp7tumK/ZnT37o7X0FUEXrxNi+dkhmeJ0gsaiN+JQGNUewvpSk\nPIAXKvi908aSfCGjs7bGlJCJCuDuL5d6m7hZnP9rt9fJc70GElPpG0jc9fXwlz7T\nlsPb2ecatmG05Y4jPwdC+oN4MNCv9yQzEvCVMzl76EJaM602kIHC1CISn0rDFmYd\n9rSN7XPlNJw1F6PbpJ/BWQ+pXHKw3OEwNTETAUNYiVGnZU+B7a7bZC9f6/aPbJuV\nt8Qmg+UnDvW1Y8gmfHnxaWG2f5TDBvCHmcYtucIZPLQD4trAozC4ryqlmCWQNKbt\n0wIDAQAB\n-----END PUBLIC KEY-----\n"},"summary":"\u003cp\u003ehey yo this is my profile!\u003c/p\u003e","type":"Person","url":"http://localhost:8080/@the_mighty_zork"}`, trimmed)
+}
+
 func (suite *InternalToASTestSuite) TestOutboxToASCollection() {
 	testAccount := suite.testAccounts["admin_account"]
 	ctx := context.Background()