Support multiple sets of transport keys per contact.

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

@@ -6,7 +6,7 @@ import javax.annotation.concurrent.Immutable;
 
 /**
  * Type-safe wrapper for an integer that uniquely identifies a contact within
- * the scope of a single node.
+ * the scope of the local device.
  */
 @Immutable
 @NotNullByDefault

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

@@ -18,6 +18,8 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
+import org.briarproject.bramble.api.transport.KeySet;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
@@ -102,10 +104,11 @@ public interface DatabaseComponent {
 			throws DbException;
 
 	/**
-	 * Stores transport keys for a newly added contact.
+	 * Stores the given transport keys, optionally binding them to the given
+	 * contact, and returns a key set ID.
 	 */
-	void addTransportKeys(Transaction txn, ContactId c, TransportKeys k)
-			throws DbException;
+	KeySetId addTransportKeys(Transaction txn, @Nullable ContactId c,
+			TransportKeys k) throws DbException;
 
 	/**
 	 * Returns true if the database contains the given contact for the given
@@ -394,8 +397,8 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<ContactId, TransportKeys> getTransportKeys(Transaction txn,
-			TransportId t) throws DbException;
+	Collection<KeySet> getTransportKeys(Transaction txn, TransportId t)
+			throws DbException;
 
 	/**
 	 * Increments the outgoing stream counter for the given contact and
@@ -507,15 +510,15 @@ public interface DatabaseComponent {
 			Collection<MessageId> dependencies) throws DbException;
 
 	/**
-	 * Sets the reordering window for the given contact and transport in the
+	 * Sets the reordering window for the given key set and transport in the
 	 * given rotation period.
 	 */
-	void setReorderingWindow(Transaction txn, ContactId c, TransportId t,
+	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
 			long rotationPeriod, long base, byte[] bitmap) throws DbException;
 
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */
-	void updateTransportKeys(Transaction txn,
-			Map<ContactId, TransportKeys> keys) throws DbException;
+	void updateTransportKeys(Transaction txn, Collection<KeySet> keys)
+			throws DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySet.java

@@ -0,0 +1,51 @@
+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A set of transport keys for communicating with a contact. If the keys have
+ * not yet been bound to a contact, {@link #getContactId()}} returns null.
+ */
+@Immutable
+@NotNullByDefault
+public class KeySet {
+
+	private final KeySetId keySetId;
+	@Nullable
+	private final ContactId contactId;
+	private final TransportKeys transportKeys;
+
+	public KeySet(KeySetId keySetId, @Nullable ContactId contactId,
+			TransportKeys transportKeys) {
+		this.keySetId = keySetId;
+		this.contactId = contactId;
+		this.transportKeys = transportKeys;
+	}
+
+	public KeySetId getKeySetId() {
+		return keySetId;
+	}
+
+	@Nullable
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public TransportKeys getTransportKeys() {
+		return transportKeys;
+	}
+
+	@Override
+	public int hashCode() {
+		return keySetId.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof KeySet && keySetId.equals(((KeySet) o).keySetId);
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySetId.java

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Type-safe wrapper for an integer that uniquely identifies a set of transport
+ * keys within the scope of the local device.
+ * <p/>
+ * Key sets created on a given device must have increasing identifiers.
+ */
+@Immutable
+@NotNullByDefault
+public class KeySetId {
+
+	private final int id;
+
+	public KeySetId(int id) {
+		this.id = id;
+	}
+
+	public int getInt() {
+		return id;
+	}
+
+	@Override
+	public int hashCode() {
+		return id;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof KeySetId && id == ((KeySetId) o).id;
+	}
+}