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netlink: Split into generic and Linux-specific parts.

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The parts of the netlink module that are related to sockets are
Linux-specific, since only Linux has AF_NETLINK sockets.  The rest can be
built anywhere.  This commit breaks them into two modules, and builds the
generic one on all platforms.

Acked-by: Jesse Gross <jesse@nicira.com>
This commit is contained in:
Ben Pfaff
2010-12-10 09:51:03 -08:00
parent 365a25176b
commit 2fe27d5ad2
10 changed files with 931 additions and 841 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
lib/automake.mk
View File

@@ -72,6 +72,8 @@ lib_libopenvswitch_a_SOURCES = \
lib/netdev-provider.h \ lib/netdev-provider.h \
lib/netdev.c \ lib/netdev.c \
lib/netdev.h \ lib/netdev.h \
lib/netlink.c \
lib/netlink.h \
lib/nx-match.c \ lib/nx-match.c \
lib/nx-match.def \ lib/nx-match.def \
lib/nx-match.h \ lib/nx-match.h \
@@ -182,8 +184,8 @@ lib_libopenvswitch_a_SOURCES += \
lib/netdev-vport.c \ lib/netdev-vport.c \
lib/netdev-vport.h \ lib/netdev-vport.h \
lib/netlink-protocol.h \ lib/netlink-protocol.h \
lib/netlink.c \ lib/netlink-socket.c \
lib/netlink.h \ lib/netlink-socket.h \
lib/rtnetlink.c \ lib/rtnetlink.c \
lib/rtnetlink.h lib/rtnetlink.h
endif endif

1
lib/netdev-linux.c
View File

@@ -53,6 +53,7 @@
#include "netdev-provider.h" #include "netdev-provider.h"
#include "netdev-vport.h" #include "netdev-vport.h"
#include "netlink.h" #include "netlink.h"
#include "netlink-socket.h"
#include "ofpbuf.h" #include "ofpbuf.h"
#include "openflow/openflow.h" #include "openflow/openflow.h"
#include "packets.h" #include "packets.h"

814
lib/netlink-socket.c Normal file
View File

@@ -0,0 +1,814 @@
/*
* Copyright (c) 2008, 2009, 2010 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 "netlink-socket.h"
#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include "coverage.h"
#include "dynamic-string.h"
#include "netlink.h"
#include "netlink-protocol.h"
#include "ofpbuf.h"
#include "poll-loop.h"
#include "stress.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(netlink_socket);
COVERAGE_DEFINE(netlink_overflow);
COVERAGE_DEFINE(netlink_received);
COVERAGE_DEFINE(netlink_recv_retry);
COVERAGE_DEFINE(netlink_send);
COVERAGE_DEFINE(netlink_sent);
/* Linux header file confusion causes this to be undefined. */
#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif
/* A single (bad) Netlink message can in theory dump out many, many log
* messages, so the burst size is set quite high here to avoid missing useful
* information. Also, at high logging levels we log *all* Netlink messages. */
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600);
static void log_nlmsg(const char *function, int error,
const void *message, size_t size);
/* Netlink sockets. */
struct nl_sock
{
int fd;
uint32_t pid;
};
static int alloc_pid(uint32_t *);
static void free_pid(uint32_t);
/* Creates a new netlink socket for the given netlink 'protocol'
* (NETLINK_ROUTE, NETLINK_GENERIC, ...). Returns 0 and sets '*sockp' to the
* new socket if successful, otherwise returns a positive errno value.
*
* If 'multicast_group' is nonzero, the new socket subscribes to the specified
* netlink multicast group. (A netlink socket may listen to an arbitrary
* number of multicast groups, but so far we only need one at a time.)
*
* Nonzero 'so_sndbuf' or 'so_rcvbuf' override the kernel default send or
* receive buffer size, respectively.
*/
int
nl_sock_create(int protocol, int multicast_group,
size_t so_sndbuf, size_t so_rcvbuf, struct nl_sock **sockp)
{
struct nl_sock *sock;
struct sockaddr_nl local, remote;
int retval = 0;
*sockp = NULL;
sock = malloc(sizeof *sock);
if (sock == NULL) {
return ENOMEM;
}
sock->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
if (sock->fd < 0) {
VLOG_ERR("fcntl: %s", strerror(errno));
goto error;
}
retval = alloc_pid(&sock->pid);
if (retval) {
goto error;
}
if (so_sndbuf != 0
&& setsockopt(sock->fd, SOL_SOCKET, SO_SNDBUF,
&so_sndbuf, sizeof so_sndbuf) < 0) {
VLOG_ERR("setsockopt(SO_SNDBUF,%zu): %s", so_sndbuf, strerror(errno));
goto error_free_pid;
}
if (so_rcvbuf != 0
&& setsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF,
&so_rcvbuf, sizeof so_rcvbuf) < 0) {
VLOG_ERR("setsockopt(SO_RCVBUF,%zu): %s", so_rcvbuf, strerror(errno));
goto error_free_pid;
}
/* Bind local address as our selected pid. */
memset(&local, 0, sizeof local);
local.nl_family = AF_NETLINK;
local.nl_pid = sock->pid;
if (multicast_group > 0 && multicast_group <= 32) {
/* This method of joining multicast groups is supported by old kernels,
* but it only allows 32 multicast groups per protocol. */
local.nl_groups |= 1ul << (multicast_group - 1);
}
if (bind(sock->fd, (struct sockaddr *) &local, sizeof local) < 0) {
VLOG_ERR("bind(%"PRIu32"): %s", sock->pid, strerror(errno));
goto error_free_pid;
}
/* Bind remote address as the kernel (pid 0). */
memset(&remote, 0, sizeof remote);
remote.nl_family = AF_NETLINK;
remote.nl_pid = 0;
if (connect(sock->fd, (struct sockaddr *) &remote, sizeof remote) < 0) {
VLOG_ERR("connect(0): %s", strerror(errno));
goto error_free_pid;
}
/* Older kernel headers failed to define this macro. We want our programs
* to support the newer kernel features even if compiled with older
* headers, so define it ourselves in such a case. */
#ifndef NETLINK_ADD_MEMBERSHIP
#define NETLINK_ADD_MEMBERSHIP 1
#endif
/* This method of joining multicast groups is only supported by newish
* kernels, but it allows for an arbitrary number of multicast groups. */
if (multicast_group > 32
&& setsockopt(sock->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
&multicast_group, sizeof multicast_group) < 0) {
VLOG_ERR("setsockopt(NETLINK_ADD_MEMBERSHIP,%d): %s",
multicast_group, strerror(errno));
goto error_free_pid;
}
*sockp = sock;
return 0;
error_free_pid:
free_pid(sock->pid);
error:
if (retval == 0) {
retval = errno;
if (retval == 0) {
retval = EINVAL;
}
}
if (sock->fd >= 0) {
close(sock->fd);
}
free(sock);
return retval;
}
/* Destroys netlink socket 'sock'. */
void
nl_sock_destroy(struct nl_sock *sock)
{
if (sock) {
close(sock->fd);
free_pid(sock->pid);
free(sock);
}
}
/* Tries to send 'msg', which must contain a Netlink message, to the kernel on
* 'sock'. nlmsg_len in 'msg' will be finalized to match msg->size, and
* nlmsg_pid will be set to 'sock''s pid, before the message is sent.
*
* Returns 0 if successful, otherwise a positive errno value. If
* 'wait' is true, then the send will wait until buffer space is ready;
* otherwise, returns EAGAIN if the 'sock' send buffer is full. */
int
nl_sock_send(struct nl_sock *sock, const struct ofpbuf *msg, bool wait)
{
struct nlmsghdr *nlmsg = nl_msg_nlmsghdr(msg);
int error;
nlmsg->nlmsg_len = msg->size;
nlmsg->nlmsg_pid = sock->pid;
do {
int retval;
retval = send(sock->fd, msg->data, msg->size, wait ? 0 : MSG_DONTWAIT);
error = retval < 0 ? errno : 0;
} while (error == EINTR);
log_nlmsg(__func__, error, msg->data, msg->size);
if (!error) {
COVERAGE_INC(netlink_sent);
}
return error;
}
/* Tries to send the 'n_iov' chunks of data in 'iov' to the kernel on 'sock' as
* a single Netlink message. (The message must be fully formed and not require
* finalization of its nlmsg_len or nlmsg_pid fields.)
*
* Returns 0 if successful, otherwise a positive errno value. If 'wait' is
* true, then the send will wait until buffer space is ready; otherwise,
* returns EAGAIN if the 'sock' send buffer is full. */
int
nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov,
bool wait)
{
struct msghdr msg;
int error;
COVERAGE_INC(netlink_send);
memset(&msg, 0, sizeof msg);
msg.msg_iov = (struct iovec *) iov;
msg.msg_iovlen = n_iov;
do {
int retval;
retval = sendmsg(sock->fd, &msg, wait ? 0 : MSG_DONTWAIT);
error = retval < 0 ? errno : 0;
} while (error == EINTR);
if (error != EAGAIN) {
log_nlmsg(__func__, error, iov[0].iov_base, iov[0].iov_len);
if (!error) {
COVERAGE_INC(netlink_sent);
}
}
return error;
}
/* This stress option is useful for testing that OVS properly tolerates
* -ENOBUFS on NetLink sockets. Such errors are unavoidable because they can
* occur if the kernel cannot temporarily allocate enough GFP_ATOMIC memory to
* reply to a request. They can also occur if messages arrive on a multicast
* channel faster than OVS can process them. */
STRESS_OPTION(
netlink_overflow, "simulate netlink socket receive buffer overflow",
5, 1, -1, 100);
/* Tries to receive a netlink message from the kernel on 'sock'. If
* successful, stores the received message into '*bufp' and returns 0. The
* caller is responsible for destroying the message with ofpbuf_delete(). On
* failure, returns a positive errno value and stores a null pointer into
* '*bufp'.
*
* If 'wait' is true, nl_sock_recv waits for a message to be ready; otherwise,
* returns EAGAIN if the 'sock' receive buffer is empty. */
int
nl_sock_recv(struct nl_sock *sock, struct ofpbuf **bufp, bool wait)
{
uint8_t tmp;
ssize_t bufsize = 2048;
ssize_t nbytes, nbytes2;
struct ofpbuf *buf;
struct nlmsghdr *nlmsghdr;
struct iovec iov;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = 0
};
buf = ofpbuf_new(bufsize);
*bufp = NULL;
try_again:
/* Attempt to read the message. We don't know the size of the data
* yet, so we take a guess at 2048. If we're wrong, we keep trying
* and doubling the buffer size each time.
*/
nlmsghdr = ofpbuf_put_uninit(buf, bufsize);
iov.iov_base = nlmsghdr;
iov.iov_len = bufsize;
do {
nbytes = recvmsg(sock->fd, &msg, (wait ? 0 : MSG_DONTWAIT) | MSG_PEEK);
} while (nbytes < 0 && errno == EINTR);
if (nbytes < 0) {
ofpbuf_delete(buf);
return errno;
}
if (msg.msg_flags & MSG_TRUNC) {
COVERAGE_INC(netlink_recv_retry);
bufsize *= 2;
ofpbuf_reinit(buf, bufsize);
goto try_again;
}
buf->size = nbytes;
/* We successfully read the message, so recv again to clear the queue */
iov.iov_base = &tmp;
iov.iov_len = 1;
do {
nbytes2 = recvmsg(sock->fd, &msg, MSG_DONTWAIT);
} while (nbytes2 < 0 && errno == EINTR);
if (nbytes2 < 0) {
if (errno == ENOBUFS) {
/* The kernel is notifying us that a message it tried to send to us
* was dropped. We have to pass this along to the caller in case
* it wants to retry a request. So kill the buffer, which we can
* re-read next time. */
COVERAGE_INC(netlink_overflow);
ofpbuf_delete(buf);
return ENOBUFS;
} else {
VLOG_ERR_RL(&rl, "failed to remove nlmsg from socket: %s\n",
strerror(errno));
}
}
if (nbytes < sizeof *nlmsghdr
|| nlmsghdr->nlmsg_len < sizeof *nlmsghdr
|| nlmsghdr->nlmsg_len > nbytes) {
VLOG_ERR_RL(&rl, "received invalid nlmsg (%zd bytes < %d)",
bufsize, NLMSG_HDRLEN);
ofpbuf_delete(buf);
return EPROTO;
}
if (STRESS(netlink_overflow)) {
ofpbuf_delete(buf);
return ENOBUFS;
}
*bufp = buf;
log_nlmsg(__func__, 0, buf->data, buf->size);
COVERAGE_INC(netlink_received);
return 0;
}
/* Sends 'request' to the kernel via 'sock' and waits for a response. If
* successful, returns 0. On failure, returns a positive errno value.
*
* If 'replyp' is nonnull, then on success '*replyp' is set to the kernel's
* reply, which the caller is responsible for freeing with ofpbuf_delete(), and
* on failure '*replyp' is set to NULL. If 'replyp' is null, then the kernel's
* reply, if any, is discarded.
*
* nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will
* be set to 'sock''s pid, before the message is sent. NLM_F_ACK will be set
* in nlmsg_flags.
*
* The caller is responsible for destroying 'request'.
*
* Bare Netlink is an unreliable transport protocol. This function layers
* reliable delivery and reply semantics on top of bare Netlink.
*
* In Netlink, sending a request to the kernel is reliable enough, because the
* kernel will tell us if the message cannot be queued (and we will in that
* case put it on the transmit queue and wait until it can be delivered).
*
* Receiving the reply is the real problem: if the socket buffer is full when
* the kernel tries to send the reply, the reply will be dropped. However, the
* kernel sets a flag that a reply has been dropped. The next call to recv
* then returns ENOBUFS. We can then re-send the request.
*
* Caveats:
*
* 1. Netlink depends on sequence numbers to match up requests and
* replies. The sender of a request supplies a sequence number, and
* the reply echos back that sequence number.
*
* This is fine, but (1) some kernel netlink implementations are
* broken, in that they fail to echo sequence numbers and (2) this
* function will drop packets with non-matching sequence numbers, so
* that only a single request can be usefully transacted at a time.
*
* 2. Resending the request causes it to be re-executed, so the request
* needs to be idempotent.
*/
int
nl_sock_transact(struct nl_sock *sock,
const struct ofpbuf *request, struct ofpbuf **replyp)
{
uint32_t seq = nl_msg_nlmsghdr(request)->nlmsg_seq;
struct nlmsghdr *nlmsghdr;
struct ofpbuf *reply;
int retval;
if (replyp) {
*replyp = NULL;
}
/* Ensure that we get a reply even if this message doesn't ordinarily call
* for one. */
nl_msg_nlmsghdr(request)->nlmsg_flags |= NLM_F_ACK;
send:
retval = nl_sock_send(sock, request, true);
if (retval) {
return retval;
}
recv:
retval = nl_sock_recv(sock, &reply, true);
if (retval) {
if (retval == ENOBUFS) {
COVERAGE_INC(netlink_overflow);
VLOG_DBG_RL(&rl, "receive buffer overflow, resending request");
goto send;
} else {
return retval;
}
}
nlmsghdr = nl_msg_nlmsghdr(reply);
if (seq != nlmsghdr->nlmsg_seq) {
VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32,
nl_msg_nlmsghdr(reply)->nlmsg_seq, seq);
ofpbuf_delete(reply);
goto recv;
}
/* If the reply is an error, discard the reply and return the error code.
*
* Except: if the reply is just an acknowledgement (error code of 0), and
* the caller is interested in the reply (replyp != NULL), pass the reply
* up to the caller. Otherwise the caller will get a return value of 0
* and null '*replyp', which makes unwary callers likely to segfault. */
if (nl_msg_nlmsgerr(reply, &retval) && (retval || !replyp)) {
ofpbuf_delete(reply);
if (retval) {
VLOG_DBG_RL(&rl, "received NAK error=%d (%s)",
retval, strerror(retval));
}
return retval != EAGAIN ? retval : EPROTO;
}
if (replyp) {
*replyp = reply;
} else {
ofpbuf_delete(reply);
}
return 0;
}
/* Starts a Netlink "dump" operation, by sending 'request' to the kernel via
* 'sock', and initializes 'dump' to reflect the state of the operation.
*
* nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will
* be set to 'sock''s pid, before the message is sent. NLM_F_DUMP and
* NLM_F_ACK will be set in nlmsg_flags.
*
* The properties of Netlink make dump operations reliable as long as all of
* the following are true:
*
* - At most a single dump is in progress at a time on a given nl_sock.
*
* - The nl_sock is not subscribed to any multicast groups.
*
* - The nl_sock is not used to send any other messages before the dump
* operation is complete.
*
* This function provides no status indication. An error status for the entire
* dump operation is provided when it is completed by calling nl_dump_done().
*
* The caller is responsible for destroying 'request'. The caller must not
* close 'sock' before it completes the dump operation (by calling
* nl_dump_done()).
*/
void
nl_dump_start(struct nl_dump *dump,
struct nl_sock *sock, const struct ofpbuf *request)
{
struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(request);
nlmsghdr->nlmsg_flags |= NLM_F_DUMP | NLM_F_ACK;
dump->seq = nlmsghdr->nlmsg_seq;
dump->sock = sock;
dump->status = nl_sock_send(sock, request, true);
dump->buffer = NULL;
}
/* Helper function for nl_dump_next(). */
static int
nl_dump_recv(struct nl_dump *dump, struct ofpbuf **bufferp)
{
struct nlmsghdr *nlmsghdr;
struct ofpbuf *buffer;
int retval;
retval = nl_sock_recv(dump->sock, bufferp, true);
if (retval) {
return retval == EINTR ? EAGAIN : retval;
}
buffer = *bufferp;
nlmsghdr = nl_msg_nlmsghdr(buffer);
if (dump->seq != nlmsghdr->nlmsg_seq) {
VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32,
nlmsghdr->nlmsg_seq, dump->seq);
return EAGAIN;
}
if (nl_msg_nlmsgerr(buffer, &retval)) {
VLOG_INFO_RL(&rl, "netlink dump request error (%s)",
strerror(retval));
return retval && retval != EAGAIN ? retval : EPROTO;
}
return 0;
}
/* Attempts to retrieve another reply from 'dump', which must have been
* initialized with nl_dump_start().
*
* If successful, returns true and points 'reply->data' and 'reply->size' to
* the message that was retrieved. The caller must not modify 'reply' (because
* it points into the middle of a larger buffer).
*
* On failure, returns false and sets 'reply->data' to NULL and 'reply->size'
* to 0. Failure might indicate an actual error or merely the end of replies.
* An error status for the entire dump operation is provided when it is
* completed by calling nl_dump_done().
*/
bool
nl_dump_next(struct nl_dump *dump, struct ofpbuf *reply)
{
struct nlmsghdr *nlmsghdr;
reply->data = NULL;
reply->size = 0;
if (dump->status) {
return false;
}
if (dump->buffer && !dump->buffer->size) {
ofpbuf_delete(dump->buffer);
dump->buffer = NULL;
}
while (!dump->buffer) {
int retval = nl_dump_recv(dump, &dump->buffer);
if (retval) {
ofpbuf_delete(dump->buffer);
dump->buffer = NULL;
if (retval != EAGAIN) {
dump->status = retval;
return false;
}
}
}
nlmsghdr = nl_msg_next(dump->buffer, reply);
if (!nlmsghdr) {
VLOG_WARN_RL(&rl, "netlink dump reply contains message fragment");
dump->status = EPROTO;
return false;
} else if (nlmsghdr->nlmsg_type == NLMSG_DONE) {
dump->status = EOF;
return false;
}
return true;
}
/* Completes Netlink dump operation 'dump', which must have been initialized
* with nl_dump_start(). Returns 0 if the dump operation was error-free,
* otherwise a positive errno value describing the problem. */
int
nl_dump_done(struct nl_dump *dump)
{
/* Drain any remaining messages that the client didn't read. Otherwise the
* kernel will continue to queue them up and waste buffer space. */
while (!dump->status) {
struct ofpbuf reply;
if (!nl_dump_next(dump, &reply)) {
assert(dump->status);
}
}
ofpbuf_delete(dump->buffer);
return dump->status == EOF ? 0 : dump->status;
}
/* Causes poll_block() to wake up when any of the specified 'events' (which is
* a OR'd combination of POLLIN, POLLOUT, etc.) occur on 'sock'. */
void
nl_sock_wait(const struct nl_sock *sock, short int events)
{
poll_fd_wait(sock->fd, events);
}
/* Miscellaneous. */
static const struct nl_policy family_policy[CTRL_ATTR_MAX + 1] = {
[CTRL_ATTR_FAMILY_ID] = {.type = NL_A_U16},
};
static int do_lookup_genl_family(const char *name)
{
struct nl_sock *sock;
struct ofpbuf request, *reply;
struct nlattr *attrs[ARRAY_SIZE(family_policy)];
int retval;
retval = nl_sock_create(NETLINK_GENERIC, 0, 0, 0, &sock);
if (retval) {
return -retval;
}
ofpbuf_init(&request, 0);
nl_msg_put_genlmsghdr(&request, 0, GENL_ID_CTRL, NLM_F_REQUEST,
CTRL_CMD_GETFAMILY, 1);
nl_msg_put_string(&request, CTRL_ATTR_FAMILY_NAME, name);
retval = nl_sock_transact(sock, &request, &reply);
ofpbuf_uninit(&request);
if (retval) {
nl_sock_destroy(sock);
return -retval;
}
if (!nl_policy_parse(reply, NLMSG_HDRLEN + GENL_HDRLEN,
family_policy, attrs, ARRAY_SIZE(family_policy))) {
nl_sock_destroy(sock);
ofpbuf_delete(reply);
return -EPROTO;
}
retval = nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]);
if (retval == 0) {
retval = -EPROTO;
}
nl_sock_destroy(sock);
ofpbuf_delete(reply);
return retval;
}
/* If '*number' is 0, translates the given Generic Netlink family 'name' to a
* number and stores it in '*number'. If successful, returns 0 and the caller
* may use '*number' as the family number. On failure, returns a positive
* errno value and '*number' caches the errno value. */
int
nl_lookup_genl_family(const char *name, int *number)
{
if (*number == 0) {
*number = do_lookup_genl_family(name);
assert(*number != 0);
}
return *number > 0 ? 0 : -*number;
}
/* Netlink PID.
*
* Every Netlink socket must be bound to a unique 32-bit PID. By convention,
* programs that have a single Netlink socket use their Unix process ID as PID,
* and programs with multiple Netlink sockets add a unique per-socket
* identifier in the bits above the Unix process ID.
*
* The kernel has Netlink PID 0.
*/
/* Parameters for how many bits in the PID should come from the Unix process ID
* and how many unique per-socket. */
#define SOCKET_BITS 10
#define MAX_SOCKETS (1u << SOCKET_BITS)
#define PROCESS_BITS (32 - SOCKET_BITS)
#define MAX_PROCESSES (1u << PROCESS_BITS)
#define PROCESS_MASK ((uint32_t) (MAX_PROCESSES - 1))
/* Bit vector of unused socket identifiers. */
static uint32_t avail_sockets[ROUND_UP(MAX_SOCKETS, 32)];
/* Allocates and returns a new Netlink PID. */
static int
alloc_pid(uint32_t *pid)
{
int i;
for (i = 0; i < MAX_SOCKETS; i++) {
if ((avail_sockets[i / 32] & (1u << (i % 32))) == 0) {
avail_sockets[i / 32] |= 1u << (i % 32);
*pid = (getpid() & PROCESS_MASK) | (i << PROCESS_BITS);
return 0;
}
}
VLOG_ERR("netlink pid space exhausted");
return ENOBUFS;
}
/* Makes the specified 'pid' available for reuse. */
static void
free_pid(uint32_t pid)
{
int sock = pid >> PROCESS_BITS;
assert(avail_sockets[sock / 32] & (1u << (sock % 32)));
avail_sockets[sock / 32] &= ~(1u << (sock % 32));
}
static void
nlmsghdr_to_string(const struct nlmsghdr *h, struct ds *ds)
{
struct nlmsg_flag {
unsigned int bits;
const char *name;
};
static const struct nlmsg_flag flags[] = {
{ NLM_F_REQUEST, "REQUEST" },
{ NLM_F_MULTI, "MULTI" },
{ NLM_F_ACK, "ACK" },
{ NLM_F_ECHO, "ECHO" },
{ NLM_F_DUMP, "DUMP" },
{ NLM_F_ROOT, "ROOT" },
{ NLM_F_MATCH, "MATCH" },
{ NLM_F_ATOMIC, "ATOMIC" },
};
const struct nlmsg_flag *flag;
uint16_t flags_left;
ds_put_format(ds, "nl(len:%"PRIu32", type=%"PRIu16,
h->nlmsg_len, h->nlmsg_type);
if (h->nlmsg_type == NLMSG_NOOP) {
ds_put_cstr(ds, "(no-op)");
} else if (h->nlmsg_type == NLMSG_ERROR) {
ds_put_cstr(ds, "(error)");
} else if (h->nlmsg_type == NLMSG_DONE) {
ds_put_cstr(ds, "(done)");
} else if (h->nlmsg_type == NLMSG_OVERRUN) {
ds_put_cstr(ds, "(overrun)");
} else if (h->nlmsg_type < NLMSG_MIN_TYPE) {
ds_put_cstr(ds, "(reserved)");
} else {
ds_put_cstr(ds, "(family-defined)");
}
ds_put_format(ds, ", flags=%"PRIx16, h->nlmsg_flags);
flags_left = h->nlmsg_flags;
for (flag = flags; flag < &flags[ARRAY_SIZE(flags)]; flag++) {
if ((flags_left & flag->bits) == flag->bits) {
ds_put_format(ds, "[%s]", flag->name);
flags_left &= ~flag->bits;
}
}
if (flags_left) {
ds_put_format(ds, "[OTHER:%"PRIx16"]", flags_left);
}
ds_put_format(ds, ", seq=%"PRIx32", pid=%"PRIu32"(%d:%d))",
h->nlmsg_seq, h->nlmsg_pid,
(int) (h->nlmsg_pid & PROCESS_MASK),
(int) (h->nlmsg_pid >> PROCESS_BITS));
}
static char *
nlmsg_to_string(const struct ofpbuf *buffer)
{
struct ds ds = DS_EMPTY_INITIALIZER;
const struct nlmsghdr *h = ofpbuf_at(buffer, 0, NLMSG_HDRLEN);
if (h) {
nlmsghdr_to_string(h, &ds);
if (h->nlmsg_type == NLMSG_ERROR) {
const struct nlmsgerr *e;
e = ofpbuf_at(buffer, NLMSG_HDRLEN,
NLMSG_ALIGN(sizeof(struct nlmsgerr)));
if (e) {
ds_put_format(&ds, " error(%d", e->error);
if (e->error < 0) {
ds_put_format(&ds, "(%s)", strerror(-e->error));
}
ds_put_cstr(&ds, ", in-reply-to(");
nlmsghdr_to_string(&e->msg, &ds);
ds_put_cstr(&ds, "))");
} else {
ds_put_cstr(&ds, " error(truncated)");
}
} else if (h->nlmsg_type == NLMSG_DONE) {
int *error = ofpbuf_at(buffer, NLMSG_HDRLEN, sizeof *error);
if (error) {
ds_put_format(&ds, " done(%d", *error);
if (*error < 0) {
ds_put_format(&ds, "(%s)", strerror(-*error));
}
ds_put_cstr(&ds, ")");
} else {
ds_put_cstr(&ds, " done(truncated)");
}
}
} else {
ds_put_cstr(&ds, "nl(truncated)");
}
return ds.string;
}
static void
log_nlmsg(const char *function, int error,
const void *message, size_t size)
{
struct ofpbuf buffer;
char *nlmsg;
if (!VLOG_IS_DBG_ENABLED()) {
return;
}
ofpbuf_use_const(&buffer, message, size);
nlmsg = nlmsg_to_string(&buffer);
VLOG_DBG_RL(&rl, "%s (%s): %s", function, strerror(error), nlmsg);
free(nlmsg);
}

78
lib/netlink-socket.h Normal file
View File

@@ -0,0 +1,78 @@
/*
* Copyright (c) 2008, 2009, 2010 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.
*/
#ifndef NETLINK_SOCKET_H
#define NETLINK_SOCKET_H 1
/* Netlink socket definitions.
*
* Netlink is a datagram-based network protocol primarily for communication
* between user processes and the kernel, and mainly on Linux. Netlink is
* specified in RFC 3549, "Linux Netlink as an IP Services Protocol".
*
* Netlink is not suitable for use in physical networks of heterogeneous
* machines because host byte order is used throughout.
*
* This header file defines functions for working with Netlink sockets, which
* are Linux-specific. For Netlink protocol definitions, see
* netlink-protocol.h. For helper functions for working with Netlink messages,
* see netlink.h.
*/
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/uio.h>
struct ofpbuf;
struct nl_sock;
#ifndef HAVE_NETLINK
#error "netlink-socket.h is only for hosts that support Netlink sockets"
#endif
/* Netlink sockets. */
int nl_sock_create(int protocol, int multicast_group,
size_t so_sndbuf, size_t so_rcvbuf,
struct nl_sock **);
void nl_sock_destroy(struct nl_sock *);
int nl_sock_send(struct nl_sock *, const struct ofpbuf *, bool wait);
int nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov,
bool wait);
int nl_sock_recv(struct nl_sock *, struct ofpbuf **, bool wait);
int nl_sock_transact(struct nl_sock *, const struct ofpbuf *request,
struct ofpbuf **reply);
void nl_sock_wait(const struct nl_sock *, short int events);
/* Table dumping. */
struct nl_dump {
struct nl_sock *sock; /* Socket being dumped. */
uint32_t seq; /* Expected nlmsg_seq for replies. */
struct ofpbuf *buffer; /* Receive buffer currently being iterated. */
int status; /* 0=OK, EOF=done, or positive errno value. */
};
void nl_dump_start(struct nl_dump *, struct nl_sock *,
const struct ofpbuf *request);
bool nl_dump_next(struct nl_dump *, struct ofpbuf *reply);
int nl_dump_done(struct nl_dump *);
/* Miscellaneous */
int nl_lookup_genl_family(const char *name, int *number);
#endif /* netlink-socket.h */

822
lib/netlink.c
View File

@@ -19,602 +19,21 @@
#include <assert.h> #include <assert.h>
#include <errno.h> #include <errno.h>
#include <inttypes.h> #include <inttypes.h>
#include <stdio.h> #include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h> #include <unistd.h>
#include "coverage.h" #include "coverage.h"
#include "dynamic-string.h"
#include "netlink-protocol.h" #include "netlink-protocol.h"
#include "ofpbuf.h" #include "ofpbuf.h"
#include "poll-loop.h"
#include "stress.h"
#include "timeval.h" #include "timeval.h"
#include "util.h"
#include "vlog.h" #include "vlog.h"
VLOG_DEFINE_THIS_MODULE(netlink); VLOG_DEFINE_THIS_MODULE(netlink);
COVERAGE_DEFINE(netlink_overflow);
COVERAGE_DEFINE(netlink_received);
COVERAGE_DEFINE(netlink_recv_retry);
COVERAGE_DEFINE(netlink_send);
COVERAGE_DEFINE(netlink_sent);
/* Linux header file confusion causes this to be undefined. */
#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif
/* A single (bad) Netlink message can in theory dump out many, many log /* A single (bad) Netlink message can in theory dump out many, many log
* messages, so the burst size is set quite high here to avoid missing useful * messages, so the burst size is set quite high here to avoid missing useful
* information. Also, at high logging levels we log *all* Netlink messages. */ * information. Also, at high logging levels we log *all* Netlink messages. */
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600); static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600);
static void log_nlmsg(const char *function, int error,
const void *message, size_t size);
/* Netlink sockets. */
struct nl_sock
{
int fd;
uint32_t pid;
};
/* Next nlmsghdr sequence number.
*
* This implementation uses sequence numbers that are unique process-wide, to
* avoid a hypothetical race: send request, close socket, open new socket that
* reuses the old socket's PID value, send request on new socket, receive reply
* from kernel to old socket but with same PID and sequence number. (This race
* could be avoided other ways, e.g. by preventing PIDs from being quickly
* reused). */
static uint32_t next_seq;
static int alloc_pid(uint32_t *);
static void free_pid(uint32_t);
/* Creates a new netlink socket for the given netlink 'protocol'
* (NETLINK_ROUTE, NETLINK_GENERIC, ...). Returns 0 and sets '*sockp' to the
* new socket if successful, otherwise returns a positive errno value.
*
* If 'multicast_group' is nonzero, the new socket subscribes to the specified
* netlink multicast group. (A netlink socket may listen to an arbitrary
* number of multicast groups, but so far we only need one at a time.)
*
* Nonzero 'so_sndbuf' or 'so_rcvbuf' override the kernel default send or
* receive buffer size, respectively.
*/
int
nl_sock_create(int protocol, int multicast_group,
size_t so_sndbuf, size_t so_rcvbuf, struct nl_sock **sockp)
{
struct nl_sock *sock;
struct sockaddr_nl local, remote;
int retval = 0;
if (next_seq == 0) {
/* Pick initial sequence number. */
next_seq = getpid() ^ time_wall();
}
*sockp = NULL;
sock = malloc(sizeof *sock);
if (sock == NULL) {
return ENOMEM;
}
sock->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
if (sock->fd < 0) {
VLOG_ERR("fcntl: %s", strerror(errno));
goto error;
}
retval = alloc_pid(&sock->pid);
if (retval) {
goto error;
}
if (so_sndbuf != 0
&& setsockopt(sock->fd, SOL_SOCKET, SO_SNDBUF,
&so_sndbuf, sizeof so_sndbuf) < 0) {
VLOG_ERR("setsockopt(SO_SNDBUF,%zu): %s", so_sndbuf, strerror(errno));
goto error_free_pid;
}
if (so_rcvbuf != 0
&& setsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF,
&so_rcvbuf, sizeof so_rcvbuf) < 0) {
VLOG_ERR("setsockopt(SO_RCVBUF,%zu): %s", so_rcvbuf, strerror(errno));
goto error_free_pid;
}
/* Bind local address as our selected pid. */
memset(&local, 0, sizeof local);
local.nl_family = AF_NETLINK;
local.nl_pid = sock->pid;
if (multicast_group > 0 && multicast_group <= 32) {
/* This method of joining multicast groups is supported by old kernels,
* but it only allows 32 multicast groups per protocol. */
local.nl_groups |= 1ul << (multicast_group - 1);
}
if (bind(sock->fd, (struct sockaddr *) &local, sizeof local) < 0) {
VLOG_ERR("bind(%"PRIu32"): %s", sock->pid, strerror(errno));
goto error_free_pid;
}
/* Bind remote address as the kernel (pid 0). */
memset(&remote, 0, sizeof remote);
remote.nl_family = AF_NETLINK;
remote.nl_pid = 0;
if (connect(sock->fd, (struct sockaddr *) &remote, sizeof remote) < 0) {
VLOG_ERR("connect(0): %s", strerror(errno));
goto error_free_pid;
}
/* Older kernel headers failed to define this macro. We want our programs
* to support the newer kernel features even if compiled with older
* headers, so define it ourselves in such a case. */
#ifndef NETLINK_ADD_MEMBERSHIP
#define NETLINK_ADD_MEMBERSHIP 1
#endif
/* This method of joining multicast groups is only supported by newish
* kernels, but it allows for an arbitrary number of multicast groups. */
if (multicast_group > 32
&& setsockopt(sock->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
&multicast_group, sizeof multicast_group) < 0) {
VLOG_ERR("setsockopt(NETLINK_ADD_MEMBERSHIP,%d): %s",
multicast_group, strerror(errno));
goto error_free_pid;
}
*sockp = sock;
return 0;
error_free_pid:
free_pid(sock->pid);
error:
if (retval == 0) {
retval = errno;
if (retval == 0) {
retval = EINVAL;
}
}
if (sock->fd >= 0) {
close(sock->fd);
}
free(sock);
return retval;
}
/* Destroys netlink socket 'sock'. */
void
nl_sock_destroy(struct nl_sock *sock)
{
if (sock) {
close(sock->fd);
free_pid(sock->pid);
free(sock);
}
}
/* Tries to send 'msg', which must contain a Netlink message, to the kernel on
* 'sock'. nlmsg_len in 'msg' will be finalized to match msg->size, and
* nlmsg_pid will be set to 'sock''s pid, before the message is sent.
*
* Returns 0 if successful, otherwise a positive errno value. If
* 'wait' is true, then the send will wait until buffer space is ready;
* otherwise, returns EAGAIN if the 'sock' send buffer is full. */
int
nl_sock_send(struct nl_sock *sock, const struct ofpbuf *msg, bool wait)
{
struct nlmsghdr *nlmsg = nl_msg_nlmsghdr(msg);
int error;
nlmsg->nlmsg_len = msg->size;
nlmsg->nlmsg_pid = sock->pid;
do {
int retval;
retval = send(sock->fd, msg->data, msg->size, wait ? 0 : MSG_DONTWAIT);
error = retval < 0 ? errno : 0;
} while (error == EINTR);
log_nlmsg(__func__, error, msg->data, msg->size);
if (!error) {
COVERAGE_INC(netlink_sent);
}
return error;
}
/* Tries to send the 'n_iov' chunks of data in 'iov' to the kernel on 'sock' as
* a single Netlink message. (The message must be fully formed and not require
* finalization of its nlmsg_len or nlmsg_pid fields.)
*
* Returns 0 if successful, otherwise a positive errno value. If 'wait' is
* true, then the send will wait until buffer space is ready; otherwise,
* returns EAGAIN if the 'sock' send buffer is full. */
int
nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov,
bool wait)
{
struct msghdr msg;
int error;
COVERAGE_INC(netlink_send);
memset(&msg, 0, sizeof msg);
msg.msg_iov = (struct iovec *) iov;
msg.msg_iovlen = n_iov;
do {
int retval;
retval = sendmsg(sock->fd, &msg, wait ? 0 : MSG_DONTWAIT);
error = retval < 0 ? errno : 0;
} while (error == EINTR);
if (error != EAGAIN) {
log_nlmsg(__func__, error, iov[0].iov_base, iov[0].iov_len);
if (!error) {
COVERAGE_INC(netlink_sent);
}
}
return error;
}
/* This stress option is useful for testing that OVS properly tolerates
* -ENOBUFS on NetLink sockets. Such errors are unavoidable because they can
* occur if the kernel cannot temporarily allocate enough GFP_ATOMIC memory to
* reply to a request. They can also occur if messages arrive on a multicast
* channel faster than OVS can process them. */
STRESS_OPTION(
netlink_overflow, "simulate netlink socket receive buffer overflow",
5, 1, -1, 100);
/* Tries to receive a netlink message from the kernel on 'sock'. If
* successful, stores the received message into '*bufp' and returns 0. The
* caller is responsible for destroying the message with ofpbuf_delete(). On
* failure, returns a positive errno value and stores a null pointer into
* '*bufp'.
*
* If 'wait' is true, nl_sock_recv waits for a message to be ready; otherwise,
* returns EAGAIN if the 'sock' receive buffer is empty. */
int
nl_sock_recv(struct nl_sock *sock, struct ofpbuf **bufp, bool wait)
{
uint8_t tmp;
ssize_t bufsize = 2048;
ssize_t nbytes, nbytes2;
struct ofpbuf *buf;
struct nlmsghdr *nlmsghdr;
struct iovec iov;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = 0
};
buf = ofpbuf_new(bufsize);
*bufp = NULL;
try_again:
/* Attempt to read the message. We don't know the size of the data
* yet, so we take a guess at 2048. If we're wrong, we keep trying
* and doubling the buffer size each time.
*/
nlmsghdr = ofpbuf_put_uninit(buf, bufsize);
iov.iov_base = nlmsghdr;
iov.iov_len = bufsize;
do {
nbytes = recvmsg(sock->fd, &msg, (wait ? 0 : MSG_DONTWAIT) | MSG_PEEK);
} while (nbytes < 0 && errno == EINTR);
if (nbytes < 0) {
ofpbuf_delete(buf);
return errno;
}
if (msg.msg_flags & MSG_TRUNC) {
COVERAGE_INC(netlink_recv_retry);
bufsize *= 2;
ofpbuf_reinit(buf, bufsize);
goto try_again;
}
buf->size = nbytes;
/* We successfully read the message, so recv again to clear the queue */
iov.iov_base = &tmp;
iov.iov_len = 1;
do {
nbytes2 = recvmsg(sock->fd, &msg, MSG_DONTWAIT);
} while (nbytes2 < 0 && errno == EINTR);
if (nbytes2 < 0) {
if (errno == ENOBUFS) {
/* The kernel is notifying us that a message it tried to send to us
* was dropped. We have to pass this along to the caller in case
* it wants to retry a request. So kill the buffer, which we can
* re-read next time. */
COVERAGE_INC(netlink_overflow);
ofpbuf_delete(buf);
return ENOBUFS;
} else {
VLOG_ERR_RL(&rl, "failed to remove nlmsg from socket: %s\n",
strerror(errno));
}
}
if (nbytes < sizeof *nlmsghdr
|| nlmsghdr->nlmsg_len < sizeof *nlmsghdr
|| nlmsghdr->nlmsg_len > nbytes) {
VLOG_ERR_RL(&rl, "received invalid nlmsg (%zd bytes < %d)",
bufsize, NLMSG_HDRLEN);
ofpbuf_delete(buf);
return EPROTO;
}
if (STRESS(netlink_overflow)) {
ofpbuf_delete(buf);
return ENOBUFS;
}
*bufp = buf;
log_nlmsg(__func__, 0, buf->data, buf->size);
COVERAGE_INC(netlink_received);
return 0;
}
/* Sends 'request' to the kernel via 'sock' and waits for a response. If
* successful, returns 0. On failure, returns a positive errno value.
*
* If 'replyp' is nonnull, then on success '*replyp' is set to the kernel's
* reply, which the caller is responsible for freeing with ofpbuf_delete(), and
* on failure '*replyp' is set to NULL. If 'replyp' is null, then the kernel's
* reply, if any, is discarded.
*
* nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will
* be set to 'sock''s pid, before the message is sent. NLM_F_ACK will be set
* in nlmsg_flags.
*
* The caller is responsible for destroying 'request'.
*
* Bare Netlink is an unreliable transport protocol. This function layers
* reliable delivery and reply semantics on top of bare Netlink.
*
* In Netlink, sending a request to the kernel is reliable enough, because the
* kernel will tell us if the message cannot be queued (and we will in that
* case put it on the transmit queue and wait until it can be delivered).
*
* Receiving the reply is the real problem: if the socket buffer is full when
* the kernel tries to send the reply, the reply will be dropped. However, the
* kernel sets a flag that a reply has been dropped. The next call to recv
* then returns ENOBUFS. We can then re-send the request.
*
* Caveats:
*
* 1. Netlink depends on sequence numbers to match up requests and
* replies. The sender of a request supplies a sequence number, and
* the reply echos back that sequence number.
*
* This is fine, but (1) some kernel netlink implementations are
* broken, in that they fail to echo sequence numbers and (2) this
* function will drop packets with non-matching sequence numbers, so
* that only a single request can be usefully transacted at a time.
*
* 2. Resending the request causes it to be re-executed, so the request
* needs to be idempotent.
*/
int
nl_sock_transact(struct nl_sock *sock,
const struct ofpbuf *request, struct ofpbuf **replyp)
{
uint32_t seq = nl_msg_nlmsghdr(request)->nlmsg_seq;
struct nlmsghdr *nlmsghdr;
struct ofpbuf *reply;
int retval;
if (replyp) {
*replyp = NULL;
}
/* Ensure that we get a reply even if this message doesn't ordinarily call
* for one. */
nl_msg_nlmsghdr(request)->nlmsg_flags |= NLM_F_ACK;
send:
retval = nl_sock_send(sock, request, true);
if (retval) {
return retval;
}
recv:
retval = nl_sock_recv(sock, &reply, true);
if (retval) {
if (retval == ENOBUFS) {
COVERAGE_INC(netlink_overflow);
VLOG_DBG_RL(&rl, "receive buffer overflow, resending request");
goto send;
} else {
return retval;
}
}
nlmsghdr = nl_msg_nlmsghdr(reply);
if (seq != nlmsghdr->nlmsg_seq) {
VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32,
nl_msg_nlmsghdr(reply)->nlmsg_seq, seq);
ofpbuf_delete(reply);
goto recv;
}
/* If the reply is an error, discard the reply and return the error code.
*
* Except: if the reply is just an acknowledgement (error code of 0), and
* the caller is interested in the reply (replyp != NULL), pass the reply
* up to the caller. Otherwise the caller will get a return value of 0
* and null '*replyp', which makes unwary callers likely to segfault. */
if (nl_msg_nlmsgerr(reply, &retval) && (retval || !replyp)) {
ofpbuf_delete(reply);
if (retval) {
VLOG_DBG_RL(&rl, "received NAK error=%d (%s)",
retval, strerror(retval));
}
return retval != EAGAIN ? retval : EPROTO;
}
if (replyp) {
*replyp = reply;
} else {
ofpbuf_delete(reply);
}
return 0;
}
/* Starts a Netlink "dump" operation, by sending 'request' to the kernel via
* 'sock', and initializes 'dump' to reflect the state of the operation.
*
* nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will
* be set to 'sock''s pid, before the message is sent. NLM_F_DUMP and
* NLM_F_ACK will be set in nlmsg_flags.
*
* The properties of Netlink make dump operations reliable as long as all of
* the following are true:
*
* - At most a single dump is in progress at a time on a given nl_sock.
*
* - The nl_sock is not subscribed to any multicast groups.
*
* - The nl_sock is not used to send any other messages before the dump
* operation is complete.
*
* This function provides no status indication. An error status for the entire
* dump operation is provided when it is completed by calling nl_dump_done().
*
* The caller is responsible for destroying 'request'. The caller must not
* close 'sock' before it completes the dump operation (by calling
* nl_dump_done()).
*/
void
nl_dump_start(struct nl_dump *dump,
struct nl_sock *sock, const struct ofpbuf *request)
{
struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(request);
nlmsghdr->nlmsg_flags |= NLM_F_DUMP | NLM_F_ACK;
dump->seq = nlmsghdr->nlmsg_seq;
dump->sock = sock;
dump->status = nl_sock_send(sock, request, true);
dump->buffer = NULL;
}
/* Helper function for nl_dump_next(). */
static int
nl_dump_recv(struct nl_dump *dump, struct ofpbuf **bufferp)
{
struct nlmsghdr *nlmsghdr;
struct ofpbuf *buffer;
int retval;
retval = nl_sock_recv(dump->sock, bufferp, true);
if (retval) {
return retval == EINTR ? EAGAIN : retval;
}
buffer = *bufferp;
nlmsghdr = nl_msg_nlmsghdr(buffer);
if (dump->seq != nlmsghdr->nlmsg_seq) {
VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32,
nlmsghdr->nlmsg_seq, dump->seq);
return EAGAIN;
}
if (nl_msg_nlmsgerr(buffer, &retval)) {
VLOG_INFO_RL(&rl, "netlink dump request error (%s)",
strerror(retval));
return retval && retval != EAGAIN ? retval : EPROTO;
}
return 0;
}
/* Attempts to retrieve another reply from 'dump', which must have been
* initialized with nl_dump_start().
*
* If successful, returns true and points 'reply->data' and 'reply->size' to
* the message that was retrieved. The caller must not modify 'reply' (because
* it points into the middle of a larger buffer).
*
* On failure, returns false and sets 'reply->data' to NULL and 'reply->size'
* to 0. Failure might indicate an actual error or merely the end of replies.
* An error status for the entire dump operation is provided when it is
* completed by calling nl_dump_done().
*/
bool
nl_dump_next(struct nl_dump *dump, struct ofpbuf *reply)
{
struct nlmsghdr *nlmsghdr;
reply->data = NULL;
reply->size = 0;
if (dump->status) {
return false;
}
if (dump->buffer && !dump->buffer->size) {
ofpbuf_delete(dump->buffer);
dump->buffer = NULL;
}
while (!dump->buffer) {
int retval = nl_dump_recv(dump, &dump->buffer);
if (retval) {
ofpbuf_delete(dump->buffer);
dump->buffer = NULL;
if (retval != EAGAIN) {
dump->status = retval;
return false;
}
}
}
nlmsghdr = nl_msg_next(dump->buffer, reply);
if (!nlmsghdr) {
VLOG_WARN_RL(&rl, "netlink dump reply contains message fragment");
dump->status = EPROTO;
return false;
} else if (nlmsghdr->nlmsg_type == NLMSG_DONE) {
dump->status = EOF;
return false;
}
return true;
}
/* Completes Netlink dump operation 'dump', which must have been initialized
* with nl_dump_start(). Returns 0 if the dump operation was error-free,
* otherwise a positive errno value describing the problem. */
int
nl_dump_done(struct nl_dump *dump)
{
/* Drain any remaining messages that the client didn't read. Otherwise the
* kernel will continue to queue them up and waste buffer space. */
while (!dump->status) {
struct ofpbuf reply;
if (!nl_dump_next(dump, &reply)) {
assert(dump->status);
}
}
ofpbuf_delete(dump->buffer);
return dump->status == EOF ? 0 : dump->status;
}
/* Causes poll_block() to wake up when any of the specified 'events' (which is
* a OR'd combination of POLLIN, POLLOUT, etc.) occur on 'sock'. */
void
nl_sock_wait(const struct nl_sock *sock, short int events)
{
poll_fd_wait(sock->fd, events);
}
/* Netlink messages. */
/* Returns the nlmsghdr at the head of 'msg'. /* Returns the nlmsghdr at the head of 'msg'.
* *
* 'msg' must be at least as large as a nlmsghdr. */ * 'msg' must be at least as large as a nlmsghdr. */
@@ -668,6 +87,26 @@ nl_msg_reserve(struct ofpbuf *msg, size_t size)
ofpbuf_prealloc_tailroom(msg, NLMSG_ALIGN(size)); ofpbuf_prealloc_tailroom(msg, NLMSG_ALIGN(size));
} }
static uint32_t
get_nlmsg_seq(void)
{
/* Next nlmsghdr sequence number.
*
* This implementation uses sequence numbers that are unique process-wide,
* to avoid a hypothetical race: send request, close socket, open new
* socket that reuses the old socket's PID value, send request on new
* socket, receive reply from kernel to old socket but with same PID and
* sequence number. (This race could be avoided other ways, e.g. by
* preventing PIDs from being quickly reused). */
static uint32_t next_seq;
if (next_seq == 0) {
/* Pick initial sequence number. */
next_seq = getpid() ^ time_wall();
}
return next_seq++;
}
/* Puts a nlmsghdr at the beginning of 'msg', which must be initially empty. /* Puts a nlmsghdr at the beginning of 'msg', which must be initially empty.
* Uses the given 'type' and 'flags'. 'expected_payload' should be * Uses the given 'type' and 'flags'. 'expected_payload' should be
* an estimate of the number of payload bytes to be supplied; if the size of * an estimate of the number of payload bytes to be supplied; if the size of
@@ -699,7 +138,7 @@ nl_msg_put_nlmsghdr(struct ofpbuf *msg,
nlmsghdr->nlmsg_len = 0; nlmsghdr->nlmsg_len = 0;
nlmsghdr->nlmsg_type = type; nlmsghdr->nlmsg_type = type;
nlmsghdr->nlmsg_flags = flags; nlmsghdr->nlmsg_flags = flags;
nlmsghdr->nlmsg_seq = ++next_seq; nlmsghdr->nlmsg_seq = get_nlmsg_seq();
nlmsghdr->nlmsg_pid = 0; nlmsghdr->nlmsg_pid = 0;
} }
@@ -1110,220 +549,3 @@ nl_parse_nested(const struct nlattr *nla, const struct nl_policy policy[],
nl_attr_get_nested(nla, &buf); nl_attr_get_nested(nla, &buf);
return nl_policy_parse(&buf, 0, policy, attrs, n_attrs); return nl_policy_parse(&buf, 0, policy, attrs, n_attrs);
} }
/* Miscellaneous. */
static const struct nl_policy family_policy[CTRL_ATTR_MAX + 1] = {
[CTRL_ATTR_FAMILY_ID] = {.type = NL_A_U16},
};
static int do_lookup_genl_family(const char *name)
{
struct nl_sock *sock;
struct ofpbuf request, *reply;
struct nlattr *attrs[ARRAY_SIZE(family_policy)];
int retval;
retval = nl_sock_create(NETLINK_GENERIC, 0, 0, 0, &sock);
if (retval) {
return -retval;
}
ofpbuf_init(&request, 0);
nl_msg_put_genlmsghdr(&request, 0, GENL_ID_CTRL, NLM_F_REQUEST,
CTRL_CMD_GETFAMILY, 1);
nl_msg_put_string(&request, CTRL_ATTR_FAMILY_NAME, name);
retval = nl_sock_transact(sock, &request, &reply);
ofpbuf_uninit(&request);
if (retval) {
nl_sock_destroy(sock);
return -retval;
}
if (!nl_policy_parse(reply, NLMSG_HDRLEN + GENL_HDRLEN,
family_policy, attrs, ARRAY_SIZE(family_policy))) {
nl_sock_destroy(sock);
ofpbuf_delete(reply);
return -EPROTO;
}
retval = nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]);
if (retval == 0) {
retval = -EPROTO;
}
nl_sock_destroy(sock);
ofpbuf_delete(reply);
return retval;
}
/* If '*number' is 0, translates the given Generic Netlink family 'name' to a
* number and stores it in '*number'. If successful, returns 0 and the caller
* may use '*number' as the family number. On failure, returns a positive
* errno value and '*number' caches the errno value. */
int
nl_lookup_genl_family(const char *name, int *number)
{
if (*number == 0) {
*number = do_lookup_genl_family(name);
assert(*number != 0);
}
return *number > 0 ? 0 : -*number;
}
/* Netlink PID.
*
* Every Netlink socket must be bound to a unique 32-bit PID. By convention,
* programs that have a single Netlink socket use their Unix process ID as PID,
* and programs with multiple Netlink sockets add a unique per-socket
* identifier in the bits above the Unix process ID.
*
* The kernel has Netlink PID 0.
*/
/* Parameters for how many bits in the PID should come from the Unix process ID
* and how many unique per-socket. */
#define SOCKET_BITS 10
#define MAX_SOCKETS (1u << SOCKET_BITS)
#define PROCESS_BITS (32 - SOCKET_BITS)
#define MAX_PROCESSES (1u << PROCESS_BITS)
#define PROCESS_MASK ((uint32_t) (MAX_PROCESSES - 1))
/* Bit vector of unused socket identifiers. */
static uint32_t avail_sockets[ROUND_UP(MAX_SOCKETS, 32)];
/* Allocates and returns a new Netlink PID. */
static int
alloc_pid(uint32_t *pid)
{
int i;
for (i = 0; i < MAX_SOCKETS; i++) {
if ((avail_sockets[i / 32] & (1u << (i % 32))) == 0) {
avail_sockets[i / 32] |= 1u << (i % 32);
*pid = (getpid() & PROCESS_MASK) | (i << PROCESS_BITS);
return 0;
}
}
VLOG_ERR("netlink pid space exhausted");
return ENOBUFS;
}
/* Makes the specified 'pid' available for reuse. */
static void
free_pid(uint32_t pid)
{
int sock = pid >> PROCESS_BITS;
assert(avail_sockets[sock / 32] & (1u << (sock % 32)));
avail_sockets[sock / 32] &= ~(1u << (sock % 32));
}
static void
nlmsghdr_to_string(const struct nlmsghdr *h, struct ds *ds)
{
struct nlmsg_flag {
unsigned int bits;
const char *name;
};
static const struct nlmsg_flag flags[] = {
{ NLM_F_REQUEST, "REQUEST" },
{ NLM_F_MULTI, "MULTI" },
{ NLM_F_ACK, "ACK" },
{ NLM_F_ECHO, "ECHO" },
{ NLM_F_DUMP, "DUMP" },
{ NLM_F_ROOT, "ROOT" },
{ NLM_F_MATCH, "MATCH" },
{ NLM_F_ATOMIC, "ATOMIC" },
};
const struct nlmsg_flag *flag;
uint16_t flags_left;
ds_put_format(ds, "nl(len:%"PRIu32", type=%"PRIu16,
h->nlmsg_len, h->nlmsg_type);
if (h->nlmsg_type == NLMSG_NOOP) {
ds_put_cstr(ds, "(no-op)");
} else if (h->nlmsg_type == NLMSG_ERROR) {
ds_put_cstr(ds, "(error)");
} else if (h->nlmsg_type == NLMSG_DONE) {
ds_put_cstr(ds, "(done)");
} else if (h->nlmsg_type == NLMSG_OVERRUN) {
ds_put_cstr(ds, "(overrun)");
} else if (h->nlmsg_type < NLMSG_MIN_TYPE) {
ds_put_cstr(ds, "(reserved)");
} else {
ds_put_cstr(ds, "(family-defined)");
}
ds_put_format(ds, ", flags=%"PRIx16, h->nlmsg_flags);
flags_left = h->nlmsg_flags;
for (flag = flags; flag < &flags[ARRAY_SIZE(flags)]; flag++) {
if ((flags_left & flag->bits) == flag->bits) {
ds_put_format(ds, "[%s]", flag->name);
flags_left &= ~flag->bits;
}
}
if (flags_left) {
ds_put_format(ds, "[OTHER:%"PRIx16"]", flags_left);
}
ds_put_format(ds, ", seq=%"PRIx32", pid=%"PRIu32"(%d:%d))",
h->nlmsg_seq, h->nlmsg_pid,
(int) (h->nlmsg_pid & PROCESS_MASK),
(int) (h->nlmsg_pid >> PROCESS_BITS));
}
static char *
nlmsg_to_string(const struct ofpbuf *buffer)
{
struct ds ds = DS_EMPTY_INITIALIZER;
const struct nlmsghdr *h = ofpbuf_at(buffer, 0, NLMSG_HDRLEN);
if (h) {
nlmsghdr_to_string(h, &ds);
if (h->nlmsg_type == NLMSG_ERROR) {
const struct nlmsgerr *e;
e = ofpbuf_at(buffer, NLMSG_HDRLEN,
NLMSG_ALIGN(sizeof(struct nlmsgerr)));
if (e) {
ds_put_format(&ds, " error(%d", e->error);
if (e->error < 0) {
ds_put_format(&ds, "(%s)", strerror(-e->error));
}
ds_put_cstr(&ds, ", in-reply-to(");
nlmsghdr_to_string(&e->msg, &ds);
ds_put_cstr(&ds, "))");
} else {
ds_put_cstr(&ds, " error(truncated)");
}
} else if (h->nlmsg_type == NLMSG_DONE) {
int *error = ofpbuf_at(buffer, NLMSG_HDRLEN, sizeof *error);
if (error) {
ds_put_format(&ds, " done(%d", *error);
if (*error < 0) {
ds_put_format(&ds, "(%s)", strerror(-*error));
}
ds_put_cstr(&ds, ")");
} else {
ds_put_cstr(&ds, " done(truncated)");
}
}
} else {
ds_put_cstr(&ds, "nl(truncated)");
}
return ds.string;
}
static void
log_nlmsg(const char *function, int error,
const void *message, size_t size)
{
struct ofpbuf buffer;
char *nlmsg;
if (!VLOG_IS_DBG_ENABLED()) {
return;
}
ofpbuf_use_const(&buffer, message, size);
nlmsg = nlmsg_to_string(&buffer);
VLOG_DBG_RL(&rl, "%s (%s): %s", function, strerror(error), nlmsg);
free(nlmsg);
}

47
lib/netlink.h
View File

@@ -17,54 +17,27 @@
#ifndef NETLINK_H #ifndef NETLINK_H
#define NETLINK_H 1 #define NETLINK_H 1
/* Netlink interface. /* Netlink message helpers.
* *
* Netlink is a datagram-based network protocol primarily for communication * Netlink is a datagram-based network protocol primarily for communication
* between user processes and the kernel, and mainly on Linux. Netlink is * between user processes and the kernel, and mainly on Linux. Netlink is
* specified in RFC 3549, "Linux Netlink as an IP Services Protocol". * specified in RFC 3549, "Linux Netlink as an IP Services Protocol".
* *
* Netlink is not suitable for use in physical networks of heterogeneous * Netlink is not suitable for use in physical networks of heterogeneous
* machines because host byte order is used throughout. */ * machines because host byte order is used throughout.
*
* This header file defines helper functions for working with Netlink messages.
* For Netlink protocol definitions, see netlink-protocol.h. For
* Linux-specific definitions for Netlink sockets, see netlink-socket.h.
*/
#include <stdbool.h> #include <stdbool.h>
#include <sys/uio.h> #include <stddef.h>
#include <stdint.h> #include <stdint.h>
struct ofpbuf; struct ofpbuf;
struct nl_sock;
struct nlattr; struct nlattr;
/* Netlink sockets. */
int nl_sock_create(int protocol, int multicast_group,
size_t so_sndbuf, size_t so_rcvbuf,
struct nl_sock **);
void nl_sock_destroy(struct nl_sock *);
int nl_sock_send(struct nl_sock *, const struct ofpbuf *, bool wait);
int nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov,
bool wait);
int nl_sock_recv(struct nl_sock *, struct ofpbuf **, bool wait);
int nl_sock_transact(struct nl_sock *, const struct ofpbuf *request,
struct ofpbuf **reply);
void nl_sock_wait(const struct nl_sock *, short int events);
/* Table dumping. */
struct nl_dump {
struct nl_sock *sock; /* Socket being dumped. */
uint32_t seq; /* Expected nlmsg_seq for replies. */
struct ofpbuf *buffer; /* Receive buffer currently being iterated. */
int status; /* 0=OK, EOF=done, or positive errno value. */
};
void nl_dump_start(struct nl_dump *, struct nl_sock *,
const struct ofpbuf *request);
bool nl_dump_next(struct nl_dump *, struct ofpbuf *reply);
int nl_dump_done(struct nl_dump *);
/* Netlink messages. */
/* Accessing headers and data. */ /* Accessing headers and data. */
struct nlmsghdr *nl_msg_nlmsghdr(const struct ofpbuf *); struct nlmsghdr *nl_msg_nlmsghdr(const struct ofpbuf *);
struct genlmsghdr *nl_msg_genlmsghdr(const struct ofpbuf *); struct genlmsghdr *nl_msg_genlmsghdr(const struct ofpbuf *);
@@ -141,9 +114,5 @@ bool nl_policy_parse(const struct ofpbuf *, size_t offset,
struct nlattr *[], size_t n_attrs); struct nlattr *[], size_t n_attrs);
bool nl_parse_nested(const struct nlattr *, const struct nl_policy[], bool nl_parse_nested(const struct nlattr *, const struct nl_policy[],
struct nlattr *[], size_t n_attrs); struct nlattr *[], size_t n_attrs);
/* Miscellaneous. */
int nl_lookup_genl_family(const char *name, int *number);
#endif /* netlink.h */ #endif /* netlink.h */

1
lib/rtnetlink.c
View File

@@ -26,6 +26,7 @@
#include "coverage.h" #include "coverage.h"
#include "netlink.h" #include "netlink.h"
#include "netlink-socket.h"
#include "ofpbuf.h" #include "ofpbuf.h"
#include "vlog.h" #include "vlog.h"

1
utilities/nlmon.c
View File

@@ -24,6 +24,7 @@
#include <stddef.h> #include <stddef.h>
#include <linux/rtnetlink.h> #include <linux/rtnetlink.h>
#include "netlink.h" #include "netlink.h"
#include "netlink-socket.h"
#include "ofpbuf.h" #include "ofpbuf.h"
#include "poll-loop.h" #include "poll-loop.h"
#include "timeval.h" #include "timeval.h"

1
vswitchd/ovs-brcompatd.c
View File

@@ -43,6 +43,7 @@
#include "leak-checker.h" #include "leak-checker.h"
#include "netdev.h" #include "netdev.h"
#include "netlink.h" #include "netlink.h"
#include "netlink-socket.h"
#include "ofpbuf.h" #include "ofpbuf.h"
#include "openvswitch/brcompat-netlink.h" #include "openvswitch/brcompat-netlink.h"
#include "ovsdb-idl.h" #include "ovsdb-idl.h"

1
vswitchd/proc-net-compat.c
View File

@@ -25,6 +25,7 @@
#include "dynamic-string.h" #include "dynamic-string.h"
#include "hash.h" #include "hash.h"
#include "netlink-protocol.h" #include "netlink-protocol.h"
#include "netlink-socket.h"
#include "netlink.h" #include "netlink.h"
#include "ofpbuf.h" #include "ofpbuf.h"
#include "openvswitch/brcompat-netlink.h" #include "openvswitch/brcompat-netlink.h"