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/*
* Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* 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 "netlink-notifier.h"
#include <errno.h>
#include <poll.h>
#include <stdlib.h>
#include "coverage.h"
#include "netlink.h"
#include "netlink-socket.h"
#include "openvswitch/ofpbuf.h"
#include "openvswitch/vlog.h"
VLOG_DEFINE_THIS_MODULE(netlink_notifier);
COVERAGE_DEFINE(nln_changed);
static void nln_report(struct nln *nln, void *change);
struct nln {
struct nl_sock *notify_sock; /* Netlink socket. */
struct ovs_list all_notifiers; /* All nln notifiers. */
bool has_run; /* Guard for run and wait functions. */
/* Passed in by nln_create(). */
int multicast_group; /* Multicast group we listen on. */
int protocol; /* Protocol passed to nl_sock_create(). */
nln_parse_func *parse; /* Message parsing function. */
void *change; /* Change passed to parse. */
};
struct nln_notifier {
struct nln *nln; /* Parent nln. */
struct ovs_list node;
nln_notify_func *cb;
void *aux;
};
/* Creates an nln handle which may be used to manage change notifications. The
* created handle will listen for netlink messages on 'multicast_group' using
* netlink protocol 'protocol' (e.g. NETLINK_ROUTE, NETLINK_GENERIC, ...).
* Incoming messages will be parsed with 'parse' which will be passed 'change'
* as an argument. */
struct nln *
nln_create(int protocol, int multicast_group, nln_parse_func *parse,
void *change)
{
struct nln *nln;
nln = xzalloc(sizeof *nln);
nln->notify_sock = NULL;
nln->protocol = protocol;
nln->multicast_group = multicast_group;
nln->parse = parse;
nln->change = change;
nln->has_run = false;
ovs_list_init(&nln->all_notifiers);
return nln;
}
/* Destroys 'nln' by freeing any memory it has reserved and closing any sockets
* it has opened.
*
* The caller is responsible for destroying any notifiers created by this
* 'nln' before destroying 'nln'. */
void
nln_destroy(struct nln *nln)
{
if (nln) {
ovs_assert(ovs_list_is_empty(&nln->all_notifiers));
nl_sock_destroy(nln->notify_sock);
free(nln);
}
}
/* Registers 'cb' to be called with auxiliary data 'aux' with change
* notifications. The notifier is stored in 'notifier', which the caller must
* not modify or free.
*
* This is probably not the function you want. You should probably be using
* message specific notifiers like rtnetlink_link_notifier_register().
*
* Returns an initialized nln_notifier if successful, otherwise NULL. */
struct nln_notifier *
nln_notifier_create(struct nln *nln, nln_notify_func *cb, void *aux)
{
struct nln_notifier *notifier;
if (!nln->notify_sock) {
struct nl_sock *sock;
int error;
error = nl_sock_create(nln->protocol, &sock);
if (!error) {
error = nl_sock_join_mcgroup(sock, nln->multicast_group);
}
if (error) {
nl_sock_destroy(sock);
VLOG_WARN("could not create netlink socket: %s",
ovs_strerror(error));
return NULL;
}
nln->notify_sock = sock;
} else {
/* Catch up on notification work so that the new notifier won't
* receive any stale notifications. */
nln_run(nln);
}
notifier = xmalloc(sizeof *notifier);
ovs_list_push_back(&nln->all_notifiers, ¬ifier->node);
notifier->cb = cb;
notifier->aux = aux;
notifier->nln = nln;
return notifier;
}
/* Destroys 'notifier', which must have previously been created with
* nln_notifier_register(). */
void
nln_notifier_destroy(struct nln_notifier *notifier)
{
if (notifier) {
struct nln *nln = notifier->nln;
ovs_list_remove(¬ifier->node);
if (ovs_list_is_empty(&nln->all_notifiers)) {
nl_sock_destroy(nln->notify_sock);
nln->notify_sock = NULL;
}
free(notifier);
}
}
/* Calls all of the registered notifiers, passing along any as-yet-unreported
* change events. */
void
nln_run(struct nln *nln)
{
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
if (!nln->notify_sock || nln->has_run) {
return;
}
nln->has_run = true;
for (;;) {
uint64_t buf_stub[4096 / 8];
struct ofpbuf buf;
int error;
ofpbuf_use_stub(&buf, buf_stub, sizeof buf_stub);
error = nl_sock_recv(nln->notify_sock, &buf, false);
if (!error) {
if (nln->parse(&buf, nln->change)) {
nln_report(nln, nln->change);
} else {
VLOG_WARN_RL(&rl, "received bad netlink message");
nln_report(nln, NULL);
}
ofpbuf_uninit(&buf);
} else if (error == EAGAIN) {
return;
} else {
if (error == ENOBUFS) {
/* The socket buffer might be full, there could be too many
* notifications, so it makes sense to call nln_report() */
nln_report(nln, NULL);
VLOG_WARN_RL(&rl, "netlink receive buffer overflowed");
} else {
VLOG_WARN_RL(&rl, "error reading netlink socket: %s",
ovs_strerror(error));
}
return;
}
}
}
/* Causes poll_block() to wake up when change notifications are ready. */
void
nln_wait(struct nln *nln)
{
nln->has_run = false;
if (nln->notify_sock) {
nl_sock_wait(nln->notify_sock, POLLIN);
}
}
static void
nln_report(struct nln *nln, void *change)
{
struct nln_notifier *notifier;
if (change) {
COVERAGE_INC(nln_changed);
}
LIST_FOR_EACH (notifier, node, &nln->all_notifiers) {
notifier->cb(change, notifier->aux);
}
}
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