/gt945/article/details/45315911
/*
* NetMonitor.c
*
* Created on: 4月25日
* Author: tao
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <sys/types.h>
#include <asm/types.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/route.h>
#define BUFLEN 20480
#define t_assert(x) { \
if(!(x)) {err = -__LINE__;goto error;} \
}
/*Ctrl + C 退出*/
static volatile int keepRunning = 1;
void intHandler(int dummy __unused)
{
keepRunning = 0;
}
/**
* 解析RTA,并存入tb
*/
void parse_rtattr(struct rtattr **tb, int max, struct rtattr *attr, int len)
{
for (; RTA_OK(attr, len); attr = RTA_NEXT(attr, len)) {
if (attr->rta_type <= max) {
tb[attr->rta_type] = attr;
}
}
}
/**
* 显示连接信息
* 当网卡变动的时候触发这个信息,例如插/拔网线,增/减网卡设备,启用/禁用接口等.
*/
void print_ifinfomsg(struct nlmsghdr *nh)
{
int len;
struct rtattr *tb[IFLA_MAX + 1];
struct ifinfomsg *ifinfo;
//bzero(tb, sizeof(tb));
memset(tb, 0, sizeof(tb));
ifinfo = NLMSG_DATA(nh);
len = nh->nlmsg_len - NLMSG_SPACE(sizeof(*ifinfo));
parse_rtattr(tb, IFLA_MAX, IFLA_RTA (ifinfo), len);
printf("%s: %s ", (nh->nlmsg_type==RTM_NEWLINK)?"NEWLINK":"DELLINK", (ifinfo->ifi_flags & IFF_UP) ? "up" : "down");
if(tb[IFLA_IFNAME]) {
printf("%s", RTA_DATA(tb[IFLA_IFNAME]));
}
printf("\n");
}
/**
* 显示地址信息
* 当地址变动的时候触发这个信息,例如通过DHCP获取到地址后
*/
void print_ifaddrmsg(struct nlmsghdr *nh)
{
int len;
struct rtattr *tb[IFA_MAX + 1];
struct ifaddrmsg *ifaddr;
char tmp[256];
//bzero(tb, sizeof(tb));
memset(tb, 0, sizeof(tb));
ifaddr = NLMSG_DATA(nh);
len = nh->nlmsg_len - NLMSG_SPACE(sizeof(*ifaddr));
parse_rtattr(tb, IFA_MAX, IFA_RTA (ifaddr), len);
printf("%s ", (nh->nlmsg_type==RTM_NEWADDR)?"NEWADDR":"DELADDR");
if (tb[IFA_LABEL] != NULL) {
printf("%s ", RTA_DATA(tb[IFA_LABEL]));
}
if (tb[IFA_ADDRESS] != NULL) {
inet_ntop(ifaddr->ifa_family, RTA_DATA(tb[IFA_ADDRESS]), tmp, sizeof(tmp));
printf("%s ", tmp);
}
printf("\n");
}
/**
* 显示路由信息
* 当路由变动的时候触发这个信息
*/
void print_rtmsg(struct nlmsghdr *nh)
{
int len;
struct rtattr *tb[RTA_MAX + 1];
struct rtmsg *rt;
char tmp[256];
//bzero(tb, sizeof(tb));
memset(tb, 0, sizeof(tb));
rt = NLMSG_DATA(nh);
len = nh->nlmsg_len - NLMSG_SPACE(sizeof(*rt));
parse_rtattr(tb, RTA_MAX, RTM_RTA(rt), len);
printf("%s: ", (nh->nlmsg_type==RTM_NEWROUTE)?"NEWROUT":"DELROUT");
if (tb[RTA_DST] != NULL) {
inet_ntop(rt->rtm_family, RTA_DATA(tb[RTA_DST]), tmp, sizeof(tmp));
printf("RTA_DST %s ", tmp);
}
if (tb[RTA_SRC] != NULL) {
inet_ntop(rt->rtm_family, RTA_DATA(tb[RTA_SRC]), tmp, sizeof(tmp));
printf("RTA_SRC %s ", tmp);
}
if (tb[RTA_GATEWAY] != NULL) {
inet_ntop(rt->rtm_family, RTA_DATA(tb[RTA_GATEWAY]), tmp, sizeof(tmp));
printf("RTA_GATEWAY %s ", tmp);
}
printf("\n");
}
int main(int argc __unused, char *argv[] __unused)
{
int socket_fd;
int err = 0;
fd_set rd_set;
struct timeval timeout;
int select_r;
int read_r;
struct sockaddr_nl sa;
struct nlmsghdr *nh;
int len = BUFLEN;
char buff[2048];
signal(SIGINT, intHandler);
/*打开NetLink Socket*/
socket_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
t_assert(socket_fd > 0);
t_assert(!setsockopt(socket_fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)));
/*设定接收类型并绑定Socket*/
//bzero(&sa, sizeof(sa));
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV4_ROUTE | RTMGRP_IPV6_IFADDR | RTMGRP_IPV6_ROUTE;
t_assert(!bind(socket_fd, (struct sockaddr *) &sa, sizeof(sa)));
while (keepRunning) {
FD_ZERO(&rd_set);
FD_SET(socket_fd, &rd_set);
timeout.tv_sec = 5;
timeout.tv_usec = 0;
select_r = select(socket_fd + 1, &rd_set, NULL, NULL, &timeout);
if (select_r < 0) {
perror("select");
} else if (select_r > 0) {
if (FD_ISSET(socket_fd, &rd_set)) {
read_r = read(socket_fd, buff, sizeof(buff));
for (nh = (struct nlmsghdr *) buff; NLMSG_OK(nh, (unsigned)read_r); nh = NLMSG_NEXT(nh, read_r)) {
switch (nh->nlmsg_type) {
default:
/*收到些奇怪的信息*/
printf("nh->nlmsg_type = %d\n", nh->nlmsg_type);
break;
case NLMSG_DONE:
case NLMSG_ERROR:
break;
case RTM_NEWLINK:
case RTM_DELLINK:
print_ifinfomsg(nh);
break;
case RTM_NEWADDR:
case RTM_DELADDR:
print_ifaddrmsg(nh);
break;
case RTM_NEWROUTE:
case RTM_DELROUTE:
print_rtmsg(nh);
break;
}
}
}
}
}
close(socket_fd);
error:
if (err < 0) {
printf("Error at line %d\nErrno=%d\n", -err, errno);
}
return err;
}
