sd-dhcp6-client: stop IO event source when client entered bound state

Also when the client receives a reply when running in information
requesting mode.

src/libsystemd-network/sd-dhcp6-client.c

@@ -1051,6 +1051,7 @@ static int client_enter_bound_state(sd_dhcp6_client *client) {
                       DHCP6_STATE_RENEW,
                       DHCP6_STATE_REBIND));
 
+        (void) event_source_disable(client->receive_message);
         (void) event_source_disable(client->timeout_resend);
 
         r = dhcp6_lease_get_lifetime(client->lease, &lifetime_t1, &lifetime_t2, &lifetime_valid);
@@ -1152,6 +1153,8 @@ static int client_process_information(
         sd_dhcp6_lease_unref(client->lease);
         client->lease = TAKE_PTR(lease);
 
+        /* Do not call client_stop() here, as it frees the acquired lease. */
+        (void) event_source_disable(client->receive_message);
         (void) event_source_disable(client->timeout_resend);
         client_set_state(client, DHCP6_STATE_STOPPED);
 
@@ -1346,8 +1349,6 @@ static int client_receive_message(
 
         case DHCP6_STATE_BOUND:
         case DHCP6_STATE_STOPPED:
-                return 0;
-
         default:
                 assert_not_reached();
         }