+ return 0;
+}
+
+static int manager_rtnl_process_link(sd_rtnl *rtnl, sd_rtnl_message *message, void *userdata) {
+ Manager *m = userdata;
+ Link *link = NULL;
+ NetDev *netdev = NULL;
+ uint16_t type;
+ const char *name;
+ int r, ifindex;
+
+ assert(rtnl);
+ assert(message);
+ assert(m);
+
+ if (sd_rtnl_message_is_error(message)) {
+ r = sd_rtnl_message_get_errno(message);
+ if (r < 0)
+ log_warning_errno(r, "rtnl: could not receive link: %m");
+
+ return 0;
+ }
+
+ r = sd_rtnl_message_get_type(message, &type);
+ if (r < 0) {
+ log_warning_errno(r, "rtnl: could not get message type: %m");
+ return 0;
+ }
+
+ r = sd_rtnl_message_link_get_ifindex(message, &ifindex);
+ if (r < 0) {
+ log_warning_errno(r, "rtnl: could not get ifindex: %m");
+ return 0;
+ } else if (ifindex <= 0) {
+ log_warning("rtnl: received link message with invalid ifindex: %d", ifindex);
+ return 0;
+ } else
+ link_get(m, ifindex, &link);
+
+ r = sd_rtnl_message_read_string(message, IFLA_IFNAME, &name);
+ if (r < 0) {
+ log_warning_errno(r, "rtnl: received link message without ifname: %m");
+ return 0;
+ } else
+ netdev_get(m, name, &netdev);
+
+ switch (type) {
+ case RTM_NEWLINK:
+ if (!link) {
+ /* link is new, so add it */
+ r = link_add(m, message, &link);
+ if (r < 0) {
+ log_warning_errno(r, "could not add new link: %m");
+ return 0;
+ }
+ }
+
+ if (netdev) {
+ /* netdev exists, so make sure the ifindex matches */
+ r = netdev_set_ifindex(netdev, message);
+ if (r < 0) {
+ log_warning_errno(r, "could not set ifindex on netdev: %m");
+ return 0;
+ }
+ }
+
+ r = link_update(link, message);
+ if (r < 0)
+ return 0;
+
+ break;
+
+ case RTM_DELLINK:
+ link_drop(link);
+ netdev_drop(netdev);
+
+ break;
+
+ default:
+ assert_not_reached("Received invalid RTNL message type.");
+ }
+
+ return 1;
+}
+
+static int systemd_netlink_fd(void) {
+ int n, fd, rtnl_fd = -EINVAL;
+
+ n = sd_listen_fds(true);
+ if (n <= 0)
+ return -EINVAL;
+
+ for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd ++) {
+ if (sd_is_socket(fd, AF_NETLINK, SOCK_RAW, -1) > 0) {
+ if (rtnl_fd >= 0)
+ return -EINVAL;
+
+ rtnl_fd = fd;
+ }
+ }
+
+ return rtnl_fd;
+}
+
+static int manager_connect_rtnl(Manager *m) {
+ int fd, r;
+
+ assert(m);
+
+ fd = systemd_netlink_fd();
+ if (fd < 0)
+ r = sd_rtnl_open(&m->rtnl, 3, RTNLGRP_LINK, RTNLGRP_IPV4_IFADDR, RTNLGRP_IPV6_IFADDR);
+ else
+ r = sd_rtnl_open_fd(&m->rtnl, fd, 0);
+ if (r < 0)