rtnl: Introduce RT netlink sockets.
This patch adds a source module that implements RT netlink sockets for the purpose of link monitoring. Unfortunately the netlink API offers no possibility for per-port notification. Instead it forces us to use a de-multiplexing pattern. Signed-off-by: Richard Cochran <richardcochran@gmail.com>
This commit is contained in:
Richard Cochran
parent
1de59d6226
commit
0b3c045a42
2
makefile
2
makefile
@ -25,7 +25,7 @@ LDLIBS = -lm -lrt $(EXTRA_LDFLAGS)
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PRG = ptp4l pmc phc2sys hwstamp_ctl phc_ctl timemaster
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OBJ = bmc.o clock.o clockadj.o clockcheck.o config.o fault.o \
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filter.o fsm.o hash.o linreg.o mave.o mmedian.o msg.o ntpshm.o nullf.o phc.o \
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pi.o port.o print.o ptp4l.o raw.o servo.o sk.o stats.o tlv.o \
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pi.o port.o print.o ptp4l.o raw.o rtnl.o servo.o sk.o stats.o tlv.o \
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transport.o tsproc.o udp.o udp6.o uds.o util.o version.o
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OBJECTS = $(OBJ) hwstamp_ctl.o phc2sys.o phc_ctl.o pmc.o pmc_common.o \
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166
rtnl.c
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166
rtnl.c
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@ -0,0 +1,166 @@
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/**
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* @file rtnl.c
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* @note Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <asm/types.h>
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#include <linux/netlink.h>
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#include <linux/rtnetlink.h>
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#include <net/if.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <unistd.h>
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#include "print.h"
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#include "rtnl.h"
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static int rtnl_len;
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static char *rtnl_buf;
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int rtnl_close(int fd)
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{
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if (rtnl_buf) {
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free(rtnl_buf);
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rtnl_buf = NULL;
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rtnl_len = 0;
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}
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return close(fd);
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}
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int rtnl_link_query(int fd)
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{
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struct sockaddr_nl sa;
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struct msghdr msg;
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struct iovec iov;
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int cnt;
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struct {
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struct nlmsghdr hdr;
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struct rtgenmsg gen;
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} __attribute__((packed)) request;
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memset(&sa, 0, sizeof(sa));
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sa.nl_family = AF_NETLINK;
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memset(&request, 0, sizeof(request));
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request.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(request.gen));
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request.hdr.nlmsg_type = RTM_GETLINK;
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request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
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request.hdr.nlmsg_seq = 1;
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request.hdr.nlmsg_pid = 0;
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request.gen.rtgen_family = AF_UNSPEC;
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iov.iov_base = &request;
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iov.iov_len = sizeof(request);
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memset(&msg, 0, sizeof(msg));
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msg.msg_name = &sa;
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msg.msg_namelen = sizeof(sa);
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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cnt = sendmsg(fd, &msg, 0);
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if (cnt < 0) {
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pr_err("rtnl: sendmsg: %m");
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return -1;
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}
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return 0;
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}
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int rtnl_link_status(int fd, rtnl_callback cb, void *ctx)
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{
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int index, len;
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struct iovec iov;
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struct sockaddr_nl sa;
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struct msghdr msg;
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struct nlmsghdr *nh;
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struct ifinfomsg *info = NULL;
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if (!rtnl_buf) {
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rtnl_len = 4096;
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rtnl_buf = malloc(rtnl_len);
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if (!rtnl_buf) {
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pr_err("rtnl: low memory");
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return -1;
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}
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}
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iov.iov_base = rtnl_buf;
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iov.iov_len = rtnl_len;
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memset(&msg, 0, sizeof(msg));
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msg.msg_name = &sa;
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msg.msg_namelen = sizeof(sa);
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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len = recvmsg(fd, &msg, MSG_PEEK | MSG_TRUNC);
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if (len < 1) {
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pr_err("rtnl: recvmsg: %m");
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return -1;
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}
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if (len > rtnl_len) {
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free(rtnl_buf);
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rtnl_len = len;
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rtnl_buf = malloc(len);
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if (!rtnl_buf) {
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pr_err("rtnl: failed to resize to %d bytes", len);
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return -1;
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}
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iov.iov_base = rtnl_buf;
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iov.iov_len = rtnl_len;
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}
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len = recvmsg(fd, &msg, 0);
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if (len < 1) {
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pr_err("rtnl: recvmsg: %m");
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return -1;
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}
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nh = (struct nlmsghdr *) rtnl_buf;
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for ( ; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
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if (nh->nlmsg_type == RTM_NEWLINK) {
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info = NLMSG_DATA(nh);
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index = info->ifi_index;
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pr_debug("interface index %d is %s", index,
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info->ifi_flags & IFF_RUNNING ? "up" : "down");
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cb(ctx, index, info->ifi_flags & IFF_RUNNING ? 1 : 0);
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}
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}
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return 0;
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}
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int rtnl_open(void)
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{
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int fd;
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struct sockaddr_nl sa;
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memset(&sa, 0, sizeof(sa));
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sa.nl_family = AF_NETLINK;
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sa.nl_groups = RTMGRP_LINK;
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fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
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if (fd < 0) {
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pr_err("failed to open netlink socket: %m");
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return -1;
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}
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if (bind(fd, (struct sockaddr *) &sa, sizeof(sa))) {
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pr_err("failed to bind netlink socket: %m");
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return -1;
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}
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return fd;
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}
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54
rtnl.h
Normal file
54
rtnl.h
Normal file
@ -0,0 +1,54 @@
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/**
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* @file rtnl.h
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* @brief Interface link status via RT netlink
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* @note Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_RTNL_H
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#define HAVE_RTNL_H
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typedef void (*rtnl_callback)(void *ctx, int index, int linkup);
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/**
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* Close a RT netlink socket.
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* @param fd A socket obtained via rtnl_open().
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* @return Zero on success, non-zero otherwise.
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*/
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int rtnl_close(int fd);
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/**
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* Request the link status from the kernel.
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* @param fd A socket obtained via rtnl_open().
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* @return Zero on success, non-zero otherwise.
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*/
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int rtnl_link_query(int fd);
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/**
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* Read kernel messages looking for a link up/down events.
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* @param fd Readable socket obtained via rtnl_open().
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* @param cb Callback function to be invoked on each event.
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* @param ctx Private context passed to the callback.
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* @return Zero on success, non-zero otherwise.
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*/
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int rtnl_link_status(int fd, rtnl_callback cb, void *ctx);
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/**
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* Open a RT netlink socket for monitoring link state.
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* @return A valid socket, or -1 on error.
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*/
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int rtnl_open(void);
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#endif
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