linuxptp/rtnl.c

168 lines
3.8 KiB
C

/**
* @file rtnl.c
* @note Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <asm/types.h>
#include <sys/socket.h> /* Must come before linux/netlink.h on some systems. */
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <net/if.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "print.h"
#include "rtnl.h"
static int rtnl_len;
static char *rtnl_buf;
int rtnl_close(int fd)
{
if (rtnl_buf) {
free(rtnl_buf);
rtnl_buf = NULL;
rtnl_len = 0;
}
return close(fd);
}
int rtnl_link_query(int fd)
{
struct sockaddr_nl sa;
struct msghdr msg;
struct iovec iov;
int cnt;
struct {
struct nlmsghdr hdr;
struct rtgenmsg gen;
} __attribute__((packed)) request;
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
memset(&request, 0, sizeof(request));
request.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(request.gen));
request.hdr.nlmsg_type = RTM_GETLINK;
request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
request.hdr.nlmsg_seq = 1;
request.hdr.nlmsg_pid = 0;
request.gen.rtgen_family = AF_UNSPEC;
iov.iov_base = &request;
iov.iov_len = sizeof(request);
memset(&msg, 0, sizeof(msg));
msg.msg_name = &sa;
msg.msg_namelen = sizeof(sa);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
cnt = sendmsg(fd, &msg, 0);
if (cnt < 0) {
pr_err("rtnl: sendmsg: %m");
return -1;
}
return 0;
}
int rtnl_link_status(int fd, rtnl_callback cb, void *ctx)
{
int index, len;
struct iovec iov;
struct sockaddr_nl sa;
struct msghdr msg;
struct nlmsghdr *nh;
struct ifinfomsg *info = NULL;
if (!rtnl_buf) {
rtnl_len = 4096;
rtnl_buf = malloc(rtnl_len);
if (!rtnl_buf) {
pr_err("rtnl: low memory");
return -1;
}
}
iov.iov_base = rtnl_buf;
iov.iov_len = rtnl_len;
memset(&msg, 0, sizeof(msg));
msg.msg_name = &sa;
msg.msg_namelen = sizeof(sa);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
len = recvmsg(fd, &msg, MSG_PEEK | MSG_TRUNC);
if (len < 1) {
pr_err("rtnl: recvmsg: %m");
return -1;
}
if (len > rtnl_len) {
free(rtnl_buf);
rtnl_len = len;
rtnl_buf = malloc(len);
if (!rtnl_buf) {
pr_err("rtnl: failed to resize to %d bytes", len);
return -1;
}
iov.iov_base = rtnl_buf;
iov.iov_len = rtnl_len;
}
len = recvmsg(fd, &msg, 0);
if (len < 1) {
pr_err("rtnl: recvmsg: %m");
return -1;
}
nh = (struct nlmsghdr *) rtnl_buf;
for ( ; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
if (nh->nlmsg_type == RTM_NEWLINK) {
info = NLMSG_DATA(nh);
index = info->ifi_index;
pr_debug("interface index %d is %s", index,
info->ifi_flags & IFF_RUNNING ? "up" : "down");
cb(ctx, index, info->ifi_flags & IFF_RUNNING ? 1 : 0);
}
}
return 0;
}
int rtnl_open(void)
{
int fd;
struct sockaddr_nl sa;
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
sa.nl_groups = RTNLGRP_LINK;
fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (fd < 0) {
pr_err("failed to open netlink socket: %m");
return -1;
}
if (bind(fd, (struct sockaddr *) &sa, sizeof(sa))) {
pr_err("failed to bind netlink socket: %m");
close(fd);
return -1;
}
return fd;
}