Support Mastodon's account migration (Move{Person})

src/main/java/smithereen/activitypub/handlers/PersonMovePersonHandler.java

@@ -0,0 +1,102 @@
+package smithereen.activitypub.handlers;
+
+import java.net.URI;
+import java.sql.SQLException;
+import java.time.Instant;
+import java.util.HashSet;
+import java.util.List;
+
+import smithereen.ApplicationContext;
+import smithereen.activitypub.ActivityHandlerContext;
+import smithereen.activitypub.ActivityTypeHandler;
+import smithereen.activitypub.objects.activities.Move;
+import smithereen.exceptions.BadRequestException;
+import smithereen.exceptions.ObjectNotFoundException;
+import smithereen.exceptions.UserErrorException;
+import smithereen.model.ForeignUser;
+import smithereen.model.User;
+import smithereen.storage.UserStorage;
+import smithereen.util.BackgroundTaskRunner;
+
+public class PersonMovePersonHandler extends ActivityTypeHandler<ForeignUser, Move, ForeignUser>{
+	private static final HashSet<Integer> movingUsers=new HashSet<>();
+
+	@Override
+	public void handle(ActivityHandlerContext context, ForeignUser actor, Move activity, ForeignUser object) throws SQLException{
+		boolean success=false;
+		try{
+			if(actor.id!=object.id)
+				throw new BadRequestException("Actor and object IDs don't match");
+			if(activity.target==null || activity.target.link==null)
+				throw new BadRequestException("Move{Person} must have a `target` pointing to the new account");
+			URI target=activity.target.link;
+
+			synchronized(movingUsers){
+				if(movingUsers.contains(actor.id)){
+					LOG.debug("Not moving {} to {} because its previous Move activity is already being processed", actor.activityPubID, target);
+					return;
+				}
+				movingUsers.add(actor.id);
+			}
+
+			ForeignUser newUser;
+			try{
+				newUser=context.appContext.getObjectLinkResolver().resolve(target, ForeignUser.class, true, true, true);
+			}catch(ObjectNotFoundException x){
+				throw new BadRequestException("Failed to fetch the target account from "+target, x);
+			}
+			if(!newUser.alsoKnownAs.contains(actor.activityPubID))
+				throw new BadRequestException("New actor does not contain old actor's ID in `alsoKnownAs`");
+
+			if(actor.movedAt!=null){
+				LOG.debug("Not moving {} to {} because this user has already moved accounts", actor.activityPubID, target);
+				return;
+			}
+
+			actor.movedTo=newUser.id;
+			actor.movedAt=Instant.now();
+			newUser.movedFrom=actor.id;
+			context.appContext.getObjectLinkResolver().storeOrUpdateRemoteObject(actor);
+			context.appContext.getObjectLinkResolver().storeOrUpdateRemoteObject(newUser);
+
+			success=true;
+			BackgroundTaskRunner.getInstance().submit(()->performMove(context.appContext, actor, newUser));
+		}finally{
+			if(!success){
+				synchronized(movingUsers){
+					movingUsers.remove(actor.id);
+				}
+			}
+		}
+	}
+
+	private void performMove(ApplicationContext ctx, ForeignUser oldUser, ForeignUser newUser){
+		try{
+			List<Integer> localFollowers=UserStorage.getUserLocalFollowers(oldUser.id);
+			LOG.debug("Started moving {} followers for {} -> {}", localFollowers.size(), oldUser.activityPubID, newUser.activityPubID);
+			for(int id:localFollowers){
+				try{
+					User user=ctx.getUsersController().getUserOrThrow(id);
+					ctx.getFriendsController().removeFriend(user, oldUser);
+					ctx.getFriendsController().followUser(user, newUser);
+				}catch(UserErrorException|ObjectNotFoundException ignore){}
+			}
+			LOG.debug("Done moving followers for {} -> {}", oldUser.activityPubID, newUser.activityPubID);
+
+			List<User> blockingUsers=UserStorage.getBlockingUsers(oldUser.id);
+			LOG.debug("Started moving {} blocks for {} -> {}", blockingUsers.size(), oldUser.activityPubID, newUser.activityPubID);
+			for(User user:blockingUsers){
+				if(user instanceof ForeignUser)
+					continue;
+				ctx.getFriendsController().blockUser(user, newUser);
+			}
+			LOG.debug("Done moving blocks for {} -> {}", oldUser.activityPubID, newUser.activityPubID);
+		}catch(Exception x){
+			LOG.error("Failed to move {} to {}", oldUser.activityPubID, newUser.activityPubID, x);
+		}finally{
+			synchronized(movingUsers){
+				movingUsers.remove(oldUser.id);
+			}
+		}
+	}
+}

src/main/java/smithereen/activitypub/handlers/UpdatePersonHandler.java

@@ -14,6 +14,7 @@ public class UpdatePersonHandler extends ActivityTypeHandler<ForeignUser, Update
 	public void handle(ActivityHandlerContext context, ForeignUser actor, Update activity, ForeignUser object) throws SQLException{
 		if(!actor.activityPubID.equals(object.activityPubID))
 			throw new BadRequestException("Users can only update themselves");
+		object.copyLocalFields(actor);
 		UserStorage.putOrUpdateForeignUser(object);
 	}
 }

src/main/java/smithereen/activitypub/objects/ActivityPubObject.java

@@ -35,6 +35,7 @@
 import smithereen.activitypub.objects.activities.Invite;
 import smithereen.activitypub.objects.activities.Join;
 import smithereen.activitypub.objects.activities.Like;
+import smithereen.activitypub.objects.activities.Move;
 import smithereen.activitypub.objects.activities.Offer;
 import smithereen.activitypub.objects.activities.Read;
 import smithereen.activitypub.objects.activities.Reject;
@@ -593,6 +594,7 @@ public static ActivityPubObject parse(JsonObject obj, ParserContext parserContex
 			case "Remove" -> new Remove();
 			case "Flag" -> new Flag();
 			case "Read" -> new Read();
+			case "Move" -> new Move();
 
 			default -> {
 				LOG.debug("Unknown object type {}", type);

src/main/java/smithereen/activitypub/objects/activities/Move.java

@@ -0,0 +1,10 @@
+package smithereen.activitypub.objects.activities;
+
+import smithereen.activitypub.objects.Activity;
+
+public class Move extends Activity{
+	@Override
+	public String getType(){
+		return "Move";
+	}
+}

src/main/java/smithereen/controllers/ObjectLinkResolver.java

@@ -205,6 +205,11 @@ public <T> T resolveNative(URI _link, Class<T> expectedType, boolean allowFetchi
 						if(obj instanceof ForeignGroup fg){
 							fg.resolveDependencies(context, allowFetching, allowStorage);
 						}
+						if(obj instanceof ForeignUser fu){
+							if(allowStorage && fu.movedToURL!=null){
+								handleNewlyFetchedMovedUser(fu);
+							}
+						}
 						T o=convertToNativeObject(obj, expectedType);
 						if(!bypassCollectionCheck && o instanceof Post post && obj.inReplyTo==null){ // TODO make this a generalized interface OwnedObject or something
 							if(post.ownerID!=post.authorID){
@@ -360,6 +365,17 @@ public static int getUserIDFromLocalURL(URI url){
 		return Integer.parseInt(matcher.group(1));
 	}
 
+	private void handleNewlyFetchedMovedUser(ForeignUser user){
+		try{
+			User newUser=resolve(user.movedToURL, User.class, true, true, false);
+			if(newUser.alsoKnownAs.contains(user.activityPubID) && user.movedTo!=newUser.id){
+				user.movedTo=newUser.id;
+			}
+		}catch(ObjectNotFoundException x){
+			LOG.warn("User {} moved to {} but the new URL can't be fetched", user.activityPubID, user.movedToURL, x);
+		}
+	}
+
 	private record ActorToken(JsonObject token, Instant validUntil){
 		public boolean isValid(){
 			return validUntil.isAfter(Instant.now());

src/main/java/smithereen/jsonld/JLDProcessor.java

@@ -55,6 +55,8 @@ public class JLDProcessor{
 		// ActivityStreams aliases
 		lc.addProperty("sensitive", "as:sensitive");
 		lc.addProperty("manuallyApprovesFollowers", "as:manuallyApprovesFollowers");
+		lc.add("movedTo", idAndTypeObject("as:movedTo", "@id"));
+		lc.add("alsoKnownAs", idAndTypeObject("as:alsoKnownAs", "@id"));
 
 		// Mastodon aliases
 		lc.addProperty("blurhash", "toot:blurhash");

src/main/java/smithereen/model/ForeignUser.java

@@ -11,6 +11,7 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Objects;
+import java.util.stream.Collectors;
 
 import smithereen.Config;
 import smithereen.Utils;
@@ -25,6 +26,7 @@
 public class ForeignUser extends User implements ForeignActor{
 
 	private URI wall, friends, groups;
+	public URI movedToURL;
 	public boolean isServiceActor;
 
 	public static ForeignUser fromResultSet(ResultSet res) throws SQLException{
@@ -222,6 +224,16 @@ protected ActivityPubObject parseActivityPubObject(JsonObject obj, ParserContext
 				privacySettings.put(key, ps);
 			}
 		}
+		if(obj.has("movedTo")){
+			movedToURL=tryParseURL(obj.get("movedTo").getAsString());
+		}
+		if(obj.has("alsoKnownAs")){
+			alsoKnownAs=tryParseArrayOfLinksOrObjects(obj.get("alsoKnownAs"), parserContext)
+					.stream()
+					.filter(l->l.link!=null)
+					.map(l->l.link)
+					.collect(Collectors.toSet());
+		}
 
 		return this;
 	}

src/main/java/smithereen/model/User.java

@@ -9,10 +9,12 @@
 import java.net.URI;
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.time.Instant;
 import java.time.LocalDate;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 import smithereen.Config;
 import smithereen.Utils;
@@ -37,6 +39,10 @@ public class User extends Actor{
 	public Gender gender;
 	public long flags;
 	public Map<UserPrivacySettingKey, PrivacySetting> privacySettings=Map.of();
+	public int movedTo;
+	public int movedFrom;
+	public Instant movedAt;
+	public Set<URI> alsoKnownAs=new HashSet<>();
 
 	// additional profile fields
 	public boolean manuallyApprovesFollowers;
@@ -148,6 +154,18 @@ protected void fillFromResultSet(ResultSet res) throws SQLException{
 					attachment.add(pv);
 				}
 			}
+			if(o.has("aka")){
+				JsonArray aka=o.getAsJsonArray("aka");
+				for(JsonElement el:aka){
+					alsoKnownAs.add(URI.create(el.getAsString()));
+				}
+			}
+			movedTo=optInt(o, "movedTo");
+			movedFrom=optInt(o, "movedFrom");
+			if(o.has("movedAt")){
+				long moved=o.get("movedAt").getAsLong();
+				movedAt=Instant.ofEpochSecond(moved);
+			}
 		}
 
 		String privacy=res.getString("privacy");
@@ -293,6 +311,19 @@ public String serializeProfileFields(){
 		}
 		if(custom!=null)
 			o.add("custom", custom);
+		if(!alsoKnownAs.isEmpty()){
+			JsonArray aka=new JsonArray(alsoKnownAs.size());
+			for(URI uri:alsoKnownAs){
+				aka.add(uri.toString());
+			}
+			o.add("aka", aka);
+		}
+		if(movedTo>0)
+			o.addProperty("movedTo", movedTo);
+		if(movedFrom>0)
+			o.addProperty("movedFrom", movedFrom);
+		if(movedAt!=null)
+			o.addProperty("movedAt", movedAt.getEpochSecond());
 		return o.toString();
 	}
 
@@ -352,6 +383,12 @@ public Map<String, Object> getFirstLastAndGender(){
 		return Map.of("first", firstName, "last", lastName==null ? "" : lastName, "gender", gender==null ? Gender.UNKNOWN : gender);
 	}
 
+	public void copyLocalFields(User previous){
+		movedTo=previous.movedTo;
+		movedFrom=previous.movedFrom;
+		movedAt=previous.movedAt;
+	}
+
 	public enum Gender{
 		UNKNOWN,
 		MALE,

src/main/java/smithereen/routes/ActivityPubRoutes.java

@@ -56,6 +56,7 @@
 import smithereen.activitypub.handlers.OfferFollowPersonHandler;
 import smithereen.activitypub.handlers.PersonAddPersonHandler;
 import smithereen.activitypub.handlers.PersonBlockPersonHandler;
+import smithereen.activitypub.handlers.PersonMovePersonHandler;
 import smithereen.activitypub.handlers.PersonRemovePersonHandler;
 import smithereen.activitypub.handlers.PersonUndoBlockPersonHandler;
 import smithereen.activitypub.handlers.ReadNoteHandler;
@@ -97,6 +98,7 @@
 import smithereen.activitypub.objects.activities.Invite;
 import smithereen.activitypub.objects.activities.Leave;
 import smithereen.activitypub.objects.activities.Like;
+import smithereen.activitypub.objects.activities.Move;
 import smithereen.activitypub.objects.activities.Offer;
 import smithereen.activitypub.objects.activities.Read;
 import smithereen.activitypub.objects.activities.Reject;
@@ -178,6 +180,7 @@ public static void registerActivityHandlers(){
 		registerActivityHandler(ForeignUser.class, Remove.class, User.class, new PersonRemovePersonHandler());
 		registerActivityHandler(ForeignUser.class, Add.class, Group.class, new AddGroupHandler());
 		registerActivityHandler(ForeignUser.class, Remove.class, Group.class, new RemoveGroupHandler());
+		registerActivityHandler(ForeignUser.class, Move.class, ForeignUser.class, new PersonMovePersonHandler());
 
 		registerActivityHandler(ForeignGroup.class, Update.class, ForeignGroup.class, new UpdateGroupHandler());
 		registerActivityHandler(ForeignUser.class, Follow.class, Group.class, new FollowGroupHandler());

src/main/java/smithereen/routes/ProfileRoutes.java

@@ -171,6 +171,11 @@ else if(user.gender==User.Gender.FEMALE)
 					model.with("noindex", true);
 				model.with("activityPubURL", user.activityPubID);
 
+				if(user.movedTo>0){
+					User newProfile=ctx.getUsersController().getUserOrThrow(user.movedTo);
+					model.with("movedTo", newProfile);
+				}
+
 				model.addNavBarItem(user.getFullName(), null, isSelf ? l.get("this_is_you") : null);
 
 				model.with("groups", ctx.getGroupsController().getUserGroups(user, self!=null ? self.user : null, 0, 100).list);

src/main/java/smithereen/storage/UserStorage.java

@@ -793,6 +793,13 @@ public static List<URI> getUserFollowerURIs(int userID, boolean followers, int o
 		}
 	}
 
+	public static List<Integer> getUserLocalFollowers(int userID) throws SQLException{
+		try(DatabaseConnection conn=DatabaseConnectionManager.getConnection()){
+			PreparedStatement stmt=SQLQueryBuilder.prepareStatement(conn, "SELECT follower_id FROM followings INNER JOIN `users` on `users`.id=follower_id WHERE followee_id=? AND accepted=1 AND `users`.ap_id IS NULL", userID);
+			return DatabaseUtils.intResultSetToList(stmt.executeQuery());
+		}
+	}
+
 	public static void setFollowAccepted(int followerID, int followeeID, boolean accepted) throws SQLException{
 		new SQLQueryBuilder()
 				.update("followings")
@@ -921,6 +928,14 @@ public static List<User> getBlockedUsers(int selfID) throws SQLException{
 				.executeAndGetIntList());
 	}
 
+	public static List<User> getBlockingUsers(int selfID) throws SQLException{
+		return getByIdAsList(new SQLQueryBuilder()
+				.selectFrom("blocks_user_user")
+				.columns("owner_id")
+				.where("user_id=?", selfID)
+				.executeAndGetIntList());
+	}
+
 	public static boolean isDomainBlocked(int selfID, String domain) throws SQLException{
 		return new SQLQueryBuilder()
 				.selectFrom("blocks_user_domain")

src/main/resources/langs/en/profile.json

@@ -10,5 +10,7 @@
   "X_is_following_you": "{name} follows you",
   "waiting_for_X_to_accept_follow_req": "You're waiting for {name} to accept your follow request",
   "incomplete_profile": "This profile might be incomplete.",
-  "this_is_you": "(this is you)"
+  "this_is_you": "(this is you)",
+  "profile_moved": "{name} now uses another profile:",
+  "profile_moved_link": "<b>{name}</b> on {domain}"
 }

src/main/resources/langs/ru/profile.json

@@ -10,5 +10,7 @@
   "X_is_following_you": "{name} {gender, select, female {подписана} other {подписан}} на ваc",
   "waiting_for_X_to_accept_follow_req": "Вы ожидаете, пока {name} примет запрос на подписку",
   "incomplete_profile": "Информация на этой странице может быть неполной.",
-  "this_is_you": "(это вы)"
+  "this_is_you": "(это вы)",
+  "profile_moved": "{name} теперь пользуется другой страницей:",
+  "profile_moved_link": "<b>{name}</b> на {domain}"
 }

src/main/resources/templates/desktop/profile.twig

@@ -1,7 +1,13 @@
 {# @pebvariable name="user" type="smithereen.model.User" #}
 {%extends "page"%}
 {%block content%}
-{%if user.domain%}
+{% if movedTo is not null %}
+<div class="marginsAreMessy"></div>
+<div class="settingsMessage">
+	{{ L('profile_moved', {'name': user | name('first')}) }}<br/>
+	<a href="{{ movedTo.profileURL }}">{{ L('profile_moved_link', {'domain': movedTo.domain, 'name': movedTo | name}) }}</a>
+</div>
+{% elseif user.domain %}
 <div class="marginsAreMessy"></div>
 <div class="settingsMessage">
 	{{L('incomplete_profile')}}<br/>
@@ -33,7 +39,7 @@
 			<span class="ava avaPlaceholder inProfile"></span>
 			{%endif%}
 			{%endif%}
-			{% if currentUser is not null and currentUser.id!=user.id and not isSelfBlocked %}
+			{% if currentUser is not null and currentUser.id!=user.id and not isSelfBlocked and movedTo is null %}
 			<div class="profileBelowAva">
 				{% if canMessage %}
 				<a href="/my/mail/compose?to={{ user.id }}" class="button withText" onclick="showMailFormBox(this); return false;">{{ L('profile_write_message') }}</a>