Do not create PeerSession for groups we created

This needs a CreatorSession which gets created on-demand.

briar-api/src/main/java/org/briarproject/briar/api/privategroup/PrivateGroupManager.java

@@ -109,6 +109,11 @@ public interface PrivateGroupManager {
 	Collection<PrivateGroup> getPrivateGroups(Transaction txn)
 			throws DbException;
 
+	/**
+	 * Returns true if the private group with the given ID was created by us.
+	 */
+	boolean isOurPrivateGroup(Transaction txn, GroupId g) throws DbException;
+
 	/**
 	 * Returns the text of the private group message with the given ID.
 	 */

briar-core/src/main/java/org/briarproject/briar/privategroup/PrivateGroupManagerImpl.java

@@ -286,6 +286,14 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 		return privateGroups;
 	}
 
+	@Override
+	public boolean isOurPrivateGroup(Transaction txn, GroupId g)
+			throws DbException {
+		PrivateGroup group = getPrivateGroup(txn, g);
+		LocalAuthor localAuthor = identityManager.getLocalAuthor(txn);
+		return localAuthor.getId().equals(group.getCreator().getId());
+	}
+
 	@Override
 	public Collection<PrivateGroup> getPrivateGroups() throws DbException {
 		return db.transactionWithResult(true, this::getPrivateGroups);

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImpl.java

@@ -126,11 +126,15 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 		db.setGroupVisibility(txn, c.getId(), g.getId(), client);
 		// Attach the contact ID to the group
 		clientHelper.setContactId(txn, g.getId(), c.getId());
-		// If the contact belongs to any private groups, create a peer session
+		// If the contact belongs to any private groups (we didn't create),
+		// create a peer session
 		for (Group pg : db.getGroups(txn, PrivateGroupManager.CLIENT_ID,
 				PrivateGroupManager.MAJOR_VERSION)) {
-			if (privateGroupManager.isMember(txn, pg.getId(), c.getAuthor()))
+			if (privateGroupManager.isMember(txn, pg.getId(), c.getAuthor())) {
-				addingMember(txn, pg.getId(), c);
+				if (!privateGroupManager.isOurPrivateGroup(txn, pg.getId())) {
+					addingMember(txn, pg.getId(), c);
+				}
+			}
 		}
 	}
 

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationIntegrationTest.java

@@ -709,6 +709,30 @@ public class GroupInvitationIntegrationTest
 		assertTrue(deleteMessages0From1(emptySet()).allDeleted());
 	}
 
+	@Test
+	public void testInvitationAfterReAddingContacts() throws Exception {
+		// sync invitation and response back
+		sendInvitation(c0.getClock().currentTimeMillis(), null);
+		sync0To1(1, true);
+		groupInvitationManager1
+				.respondToInvitation(contactId0From1, privateGroup, true);
+		sync1To0(1, true);
+
+		// sync group join messages
+		sync0To1(2, true); // + one invitation protocol join message
+		sync1To0(1, true);
+
+		assertFalse(groupInvitationManager0
+				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+
+		// re-add contacts
+		removeAllContacts();
+		addDefaultContacts();
+
+		assertTrue(groupInvitationManager0
+				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+	}
+
 	private Collection<ConversationMessageHeader> getMessages1From0()
 			throws DbException {
 		return db0.transactionWithResult(true, txn -> groupInvitationManager0

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImplTest.java

@@ -196,6 +196,9 @@ public class GroupInvitationManagerImplTest extends BrambleMockTestCase {
 			oneOf(privateGroupManager).isMember(txn, privateGroup.getId(),
 					c.getAuthor());
 			will(returnValue(true));
+			oneOf(privateGroupManager)
+					.isOurPrivateGroup(txn, privateGroup.getId());
+			will(returnValue(false));
 		}});
 		expectAddingMember(privateGroup.getId(), c);
 	}

briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTest.java

@@ -523,10 +523,10 @@ public abstract class BriarIntegrationTest<C extends BriarIntegrationTestCompone
 		contactManager0.removeContact(contactId2From0);
 		contactManager1.removeContact(contactId0From1);
 		contactManager2.removeContact(contactId0From2);
-		assertNotNull(contactId2From1);
+		if (contactId2From1 != null)
-		contactManager1.removeContact(contactId2From1);
+			contactManager1.removeContact(contactId2From1);
-		assertNotNull(contactId1From2);
+		if (contactId1From2 != null)
-		contactManager2.removeContact(contactId1From2);
+			contactManager2.removeContact(contactId1From2);
 	}
 
 	protected void setAutoDeleteTimer(BriarIntegrationTestComponent component,