如何在Linux中以编程方式检测IP地址更改？

#include<stdio.h>
#include <stdlib.h>
#include<string.h>
#include <unistd.h>
#include<linux/netlink.h>
#include<linux/rtnetlink.h>
#include <sys/socket.h>
#include <arpa/inet.h>

int main() {
    int sock;
    struct sockaddr_nl local;
    struct msghdr msg;
    struct iovec iov;
    struct nlmsghdr *nlh;
    char buffer[4096];

    sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    if (sock < 0) {
        perror("socket");
        return 1;
    }

    memset(&local, 0, sizeof(local));
    local.nl_family = AF_NETLINK;
    local.nl_groups = RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;

    if (bind(sock, (struct sockaddr *)&local, sizeof(local)) < 0) {
        perror("bind");
        return 1;
    }

    memset(&msg, 0, sizeof(msg));
    iov.iov_base = buffer;
    iov.iov_len = sizeof(buffer);
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;

    while (1) {
        int len;

        len = recvmsg(sock, &msg, 0);
        if (len < 0) {
            perror("recvmsg");
            return 1;
        }

        nlh = (struct nlmsghdr *)buffer;
        while (NLMSG_OK(nlh, len)) {
            if (nlh->nlmsg_type == NLMSG_DONE) {
                break;
            }

            if (nlh->nlmsg_type == RTM_NEWADDR || nlh->nlmsg_type == RTM_DELADDR) {
                struct ifaddrmsg *ifa = (struct ifaddrmsg *)NLMSG_DATA(nlh);
                struct rtattr *rta = IFA_RTA(ifa);
                int rtasize = IFA_PAYLOAD(nlh);

                while (RTA_OK(rta, rtasize)) {
                    if (rta->rta_type == IFA_LOCAL || rta->rta_type == IFA_ADDRESS) {
                        char addr[INET6_ADDRSTRLEN];
                        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)RTA_DATA(rta);
                        inet_ntop(AF_INET6, &sin6->sin6_addr, addr, sizeof(addr));
                        printf("IP address %s on interface %d\n", addr, ifa->ifa_index);
                    }
                    rta = RTA_NEXT(rta, rtasize);
                }
            }

            nlh = NLMSG_NEXT(nlh, len);
        }
    }

    close(sock);
    return 0;
}

#include<stdio.h>
#include <stdlib.h>
#include<string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <arpa/inet.h>

int main() {
    int sock;
    struct ifreq ifr;
    struct sockaddr_in *sin;

    sock = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock < 0) {
        perror("socket");
        return 1;
    }

    for (int i = 0; i < 10; i++) {
        memset(&ifr, 0, sizeof(ifr));
        snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "eth%d", i);

        if (ioctl(sock, SIOCGIFADDR, &ifr) < 0) {
            continue;
        }

        sin = (struct sockaddr_in *)&ifr.ifr_addr;
        char addr[INET_ADDRSTRLEN];
        inet_ntop(AF_INET, &sin->sin_addr, addr, sizeof(addr));
        printf("IP address %s on interface %s\n", addr, ifr.ifr_name);
    }

    close(sock);
    return 0;
}