[bramble] throw exceptions when adding pending contact which exists

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java

@@ -4,8 +4,10 @@ import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.UnsupportedVersionException;
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
+import org.briarproject.bramble.api.db.PendingContactExistsException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
@@ -117,9 +119,14 @@ public interface ContactManager {
 	 * @throws FormatException If the link is invalid
 	 * @throws GeneralSecurityException If the pending contact's handshake
 	 * public key is invalid
+	 * @throws ContactExistsException If a contact with the same handshake
+	 * public key already exists
+	 * @throws PendingContactExistsException If a pending contact with the same
+	 * handshake public key already exists
 	 */
 	PendingContact addPendingContact(String link, String alias)
-			throws DbException, FormatException, GeneralSecurityException;
+			throws DbException, FormatException, GeneralSecurityException,
+			ContactExistsException, PendingContactExistsException;
 
 	/**
 	 * Returns the pending contact with the given ID.

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -83,7 +83,7 @@ public interface DatabaseComponent extends TransactionManager {
 	/**
 	 * Stores a pending contact.
 	 */
-	void addPendingContact(Transaction txn, PendingContact p)
+	void addPendingContact(Transaction txn, PendingContact p, AuthorId local)
 			throws DbException;
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/db/PendingContactExistsException.java

@@ -1,9 +1,21 @@
 package org.briarproject.bramble.api.db;
 
+import org.briarproject.bramble.api.contact.PendingContact;
+
 /**
  * Thrown when a duplicate pending contact is added to the database. This
  * exception may occur due to concurrent updates and does not indicate a
  * database error.
  */
 public class PendingContactExistsException extends DbException {
+
+	private final PendingContact pendingContact;
+
+	public PendingContactExistsException(PendingContact pendingContact) {
+		this.pendingContact = pendingContact;
+	}
+
+	public PendingContact getPendingContact() {
+		return pendingContact;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java

@@ -139,7 +139,8 @@ class ContactManagerImpl implements ContactManager, EventListener {
 				pendingContactFactory.createPendingContact(link, alias);
 		Transaction txn = db.startTransaction(false);
 		try {
-			db.addPendingContact(txn, p);
+			AuthorId local = identityManager.getLocalAuthor(txn).getId();
+			db.addPendingContact(txn, p, local);
 			KeyPair ourKeyPair = identityManager.getHandshakeKeys(txn);
 			keyManager.addPendingContact(txn, p.getId(), p.getPublicKey(),
 					ourKeyPair);

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -291,12 +291,17 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public void addPendingContact(Transaction transaction, PendingContact p)
+	public void addPendingContact(Transaction transaction, PendingContact p,
-			throws DbException {
+			AuthorId local) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
-		if (db.containsPendingContact(txn, p.getId()))
+		Contact contact = db.getContact(txn, p.getPublicKey(), local);
-			throw new PendingContactExistsException();
+		if (contact != null)
+			throw new ContactExistsException(local, contact.getAuthor());
+		if (db.containsPendingContact(txn, p.getId())) {
+			PendingContact existing = db.getPendingContact(txn, p.getId());
+			throw new PendingContactExistsException(existing);
+		}
 		db.addPendingContact(txn, p);
 		transaction.attach(new PendingContactAddedEvent(p));
 	}