+/*
+ * Copyright (c) 2009 Nicira Networks.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include "rtnetlink.h"
+
+#include <errno.h>
+#include <sys/socket.h>
+#include <linux/rtnetlink.h>
+#include <net/if.h>
+#include <poll.h>
+
+#include "coverage.h"
+#include "netlink.h"
+#include "ofpbuf.h"
+
+#define THIS_MODULE VLM_rtnetlink
+#include "vlog.h"
+
+/* rtnetlink socket. */
+static struct nl_sock *notify_sock;
+
+/* All registered notifiers. */
+static struct list all_notifiers = LIST_INITIALIZER(&all_notifiers);
+
+static void rtnetlink_report_change(const struct nlmsghdr *,
+ const struct ifinfomsg *,
+ struct nlattr *attrs[]);
+static void rtnetlink_report_notify_error(void);
+
+/* Registers 'cb' to be called with auxiliary data 'aux' with network device
+ * change notifications. The notifier is stored in 'notifier', which the
+ * caller must not modify or free.
+ *
+ * This is probably not the function that you want. You should probably be
+ * using dpif_port_poll() or netdev_monitor_create(), which unlike this
+ * function are not Linux-specific.
+ *
+ * Returns 0 if successful, otherwise a positive errno value. */
+int
+rtnetlink_notifier_register(struct rtnetlink_notifier *notifier,
+ rtnetlink_notify_func *cb, void *aux)
+{
+ if (!notify_sock) {
+ int error = nl_sock_create(NETLINK_ROUTE, RTNLGRP_LINK, 0, 0,
+ ¬ify_sock);
+ if (error) {
+ VLOG_WARN("could not create rtnetlink socket: %s",
+ strerror(error));
+ return error;
+ }
+ } else {
+ /* Catch up on notification work so that the new notifier won't
+ * receive any stale notifications. */
+ rtnetlink_notifier_run();
+ }
+
+ list_push_back(&all_notifiers, ¬ifier->node);
+ notifier->cb = cb;
+ notifier->aux = aux;
+ return 0;
+}
+
+/* Cancels notification on 'notifier', which must have previously been
+ * registered with lxnetdev_notifier_register(). */
+void
+rtnetlink_notifier_unregister(struct rtnetlink_notifier *notifier)
+{
+ list_remove(¬ifier->node);
+ if (list_is_empty(&all_notifiers)) {
+ nl_sock_destroy(notify_sock);
+ notify_sock = NULL;
+ }
+}
+
+/* Calls all of the registered notifiers, passing along any as-yet-unreported
+ * netdev change events. */
+void
+rtnetlink_notifier_run(void)
+{
+ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
+
+ if (!notify_sock) {
+ return;
+ }
+
+ for (;;) {
+ /* Policy for RTNLGRP_LINK messages.
+ *
+ * There are *many* more fields in these messages, but currently we
+ * only care about these fields. */
+ static const struct nl_policy rtnetlink_policy[] = {
+ [IFLA_IFNAME] = { .type = NL_A_STRING, .optional = false },
+ [IFLA_MASTER] = { .type = NL_A_U32, .optional = true },
+ };
+
+ struct nlattr *attrs[ARRAY_SIZE(rtnetlink_policy)];
+ struct ofpbuf *buf;
+ int error;
+
+ error = nl_sock_recv(notify_sock, &buf, false);
+ if (!error) {
+ if (nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct ifinfomsg),
+ rtnetlink_policy,
+ attrs, ARRAY_SIZE(rtnetlink_policy))) {
+ struct ifinfomsg *ifinfo;
+
+ ifinfo = (void *) ((char *) buf->data + NLMSG_HDRLEN);
+ rtnetlink_report_change(buf->data, ifinfo, attrs);
+ } else {
+ VLOG_WARN_RL(&rl, "received bad rtnl message");
+ rtnetlink_report_notify_error();
+ }
+ ofpbuf_delete(buf);
+ } else if (error == EAGAIN) {
+ return;
+ } else {
+ if (error == ENOBUFS) {
+ VLOG_WARN_RL(&rl, "rtnetlink receive buffer overflowed");
+ } else {
+ VLOG_WARN_RL(&rl, "error reading rtnetlink socket: %s",
+ strerror(error));
+ }
+ rtnetlink_report_notify_error();
+ }
+ }
+}
+
+/* Causes poll_block() to wake up when network device change notifications are
+ * ready. */
+void
+rtnetlink_notifier_wait(void)
+{
+ if (notify_sock) {
+ nl_sock_wait(notify_sock, POLLIN);
+ }
+}
+
+static void
+rtnetlink_report_change(const struct nlmsghdr *nlmsg,
+ const struct ifinfomsg *ifinfo,
+ struct nlattr *attrs[])
+{
+ struct rtnetlink_notifier *notifier;
+ struct rtnetlink_change change;
+
+ COVERAGE_INC(rtnetlink_changed);
+
+ change.nlmsg_type = nlmsg->nlmsg_type;
+ change.ifi_index = ifinfo->ifi_index;
+ change.ifname = nl_attr_get_string(attrs[IFLA_IFNAME]);
+ change.master_ifindex = (attrs[IFLA_MASTER]
+ ? nl_attr_get_u32(attrs[IFLA_MASTER]) : 0);
+
+ LIST_FOR_EACH (notifier, struct rtnetlink_notifier, node,
+ &all_notifiers) {
+ notifier->cb(&change, notifier->aux);
+ }
+}
+
+static void
+rtnetlink_report_notify_error(void)
+{
+ struct rtnetlink_notifier *notifier;
+
+ LIST_FOR_EACH (notifier, struct rtnetlink_notifier, node,
+ &all_notifiers) {
+ notifier->cb(NULL, notifier->aux);
+ }
+}