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ovs/lib/netlink-notifier.c
Thadeu Lima de Souza Cascardo 8e2b26562c netlink-notifier: change message to a less scary one
"received bad netlink message" may be interpreted as a corrupt netlink message.
However, the parse functions may return failure when the message contains
unexpected attributes or misses non optional attributes. Indicating the message
contained "unexpected contents" will avoid some interpretation that there may be
some netlink message corruption.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@redhat.com>
Cc: Aaron Conole <aconole@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
2016-06-23 14:57:35 -07:00

243 lines
7.0 KiB
C

/*
* 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(const struct nln *nln, void *change, int group);
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 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;
int multicast_group; /* Multicast group we listen on. */
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, nln_parse_func *parse, void *change)
{
struct nln *nln;
nln = xzalloc(sizeof *nln);
nln->notify_sock = NULL;
nln->protocol = protocol;
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, int multicast_group, nln_notify_func *cb,
void *aux)
{
struct nln_notifier *notifier;
int error;
if (!nln->notify_sock) {
struct nl_sock *sock;
error = nl_sock_create(nln->protocol, &sock);
if (error) {
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);
}
error = nl_sock_join_mcgroup(nln->notify_sock, multicast_group);
if (error) {
VLOG_WARN("could not join netlink multicast group: %s",
ovs_strerror(error));
return NULL;
}
notifier = xmalloc(sizeof *notifier);
notifier->multicast_group = multicast_group;
notifier->cb = cb;
notifier->aux = aux;
notifier->nln = nln;
ovs_list_push_back(&nln->all_notifiers, &notifier->node);
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;
struct nln_notifier *iter;
int count = 0;
ovs_list_remove(&notifier->node);
/* Leave the group if no other notifier is interested in it. */
LIST_FOR_EACH (iter, node, &nln->all_notifiers) {
if (iter->multicast_group == notifier->multicast_group) {
count++;
}
}
if (count == 0) {
nl_sock_leave_mcgroup(nln->notify_sock, notifier->multicast_group);
}
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) {
int group = nln->parse(&buf, nln->change);
if (group != 0) {
nln_report(nln, nln->change, group);
} else {
VLOG_WARN_RL(&rl, "unexpected netlink message contents");
nln_report(nln, NULL, 0);
}
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, 0);
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(const struct nln *nln, void *change, int group)
{
struct nln_notifier *notifier;
if (change) {
COVERAGE_INC(nln_changed);
}
LIST_FOR_EACH (notifier, node, &nln->all_notifiers) {
if (!change || group == notifier->multicast_group) {
notifier->cb(change, notifier->aux);
}
}
}