wtclient: add TerminateSession method

watchtower/wtclient/manager.go

@@ -43,6 +43,10 @@ type ClientManager interface {
 	// be used while the tower is inactive.
 	DeactivateTower(pubKey *btcec.PublicKey) error
 
+	// TerminateSession sets the given session's status to CSessionTerminal
+	// meaning that it will not be used again.
+	TerminateSession(id wtdb.SessionID) error
+
 	// Stats returns the in-memory statistics of the client since startup.
 	Stats() ClientStats
 
@@ -436,6 +440,23 @@ func (m *Manager) RemoveTower(key *btcec.PublicKey, addr net.Addr) error {
 	return nil
 }
 
+// TerminateSession sets the given session's status to CSessionTerminal meaning
+// that it will not be used again.
+func (m *Manager) TerminateSession(id wtdb.SessionID) error {
+	m.clientsMu.Lock()
+	defer m.clientsMu.Unlock()
+
+	for _, client := range m.clients {
+		err := client.terminateSession(id)
+		if err != nil {
+			return err
+		}
+	}
+
+	// Finally, mark the session as terminated in the DB.
+	return m.cfg.DB.TerminateSession(id)
+}
+
 // DeactivateTower sets the given tower's status to inactive so that it is not
 // considered for session negotiation. Its sessions will also not be used while
 // the tower is inactive.