Завершите протестированный пример на C с уведомлениями, просматриваемыми в отдельном потоке:
#include <sys/socket.h> // AF_INET, socket(), bind()
#include <ifaddrs.h> // struct ifaddrs, getifaddrs()
#include <netinet/in.h> // struct sockaddr_in
#include <arpa/inet.h> // inet_ntoa(), htonl()
#include <net/if.h> // if_indextoname()
#include <pthread.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <stdbool.h>
typedef enum {
IP_ADDR_ADD,
IP_ADDR_REMOVE
} ip_address_change_notification_type_t;
typedef void (*ip_address_change_notification_callback_t)(ip_address_change_notification_type_t type, uint32_t ipaddr, void *userdata);
static int ip_address_change_notification_socket = -1;
static pthread_t ip_address_change_notification_thread;
static ip_address_change_notification_callback_t ip_address_change_notification_callback;
static void *ip_address_change_notification_callback_userdata;
void *ip_address_change_notification_worker(void *arg)
{
fprintf(stderr, "ip_address_change_notification_worker entered.\n");
if (ip_address_change_notification_socket == -1) {
goto done;
}
char buffer[4096];
struct nlmsghdr *nlh = (struct nlmsghdr *)buffer;
int len;
while ((len = recv(ip_address_change_notification_socket, nlh, sizeof(buffer), 0)) > 0) {
for (; (NLMSG_OK(nlh, len)) && (nlh->nlmsg_type != NLMSG_DONE); nlh = NLMSG_NEXT(nlh, len)) {
if (nlh->nlmsg_type == RTM_NEWADDR) {
fprintf(stderr, "Netlink: RTM_NEWADDR\n");
} else if (nlh->nlmsg_type == RTM_DELADDR) {
fprintf(stderr, "Netlink: RTM_DELADDR\n");
} else {
fprintf(stderr, "Netlink: nlmsg_type=%d\n", nlh->nlmsg_type);
continue; // Some other kind of announcement.
}
struct ifaddrmsg *ifa = (struct ifaddrmsg *)NLMSG_DATA(nlh);
struct rtattr *rth = IFA_RTA(ifa);
int rtl = IFA_PAYLOAD(nlh);
for (; rtl && RTA_OK(rth, rtl); rth = RTA_NEXT(rth,rtl)) {
char name[IFNAMSIZ];
uint32_t ipaddr;
if (rth->rta_type != IFA_LOCAL) continue;
ipaddr = *((uint32_t *)RTA_DATA(rth)); // In network byte-order.
fprintf(stderr, "Interface %s %s has IP address %s\n", if_indextoname(ifa->ifa_index, name), (nlh->nlmsg_type == RTM_NEWADDR ? "now" : "no longer"), inet_ntoa(*((struct in_addr *)&ipaddr)));
if (ip_address_change_notification_callback) (*ip_address_change_notification_callback)((nlh->nlmsg_type == RTM_NEWADDR ? IP_ADDR_ADD : IP_ADDR_REMOVE), ipaddr, ip_address_change_notification_callback_userdata);
}
}
}
done:
fprintf(stderr, "ip_address_change_notification_worker exited.\n");
return (NULL);
}
bool begin_ip_address_change_notifications(ip_address_change_notification_callback_t callback, void *userdata)
{
if (ip_address_change_notification_socket != -1) return false;
ip_address_change_notification_callback = callback;
ip_address_change_notification_callback_userdata = userdata;
if ((ip_address_change_notification_socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) == -1) {
perror("begin_ip_address_change_notifications socket");
return false;
}
struct sockaddr_nl addr;
memset(&addr, 0, sizeof(addr));
addr.nl_family = AF_NETLINK;
addr.nl_groups = RTMGRP_IPV4_IFADDR;
if (bind(ip_address_change_notification_socket, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
perror("begin_ip_address_change_notifications bind");
goto bail;
}
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, 1); // Preclude the need to do pthread_join on the thread after it exits.
int err = pthread_create(&ip_address_change_notification_thread, &attr, ip_address_change_notification_worker, NULL);
pthread_attr_destroy(&attr);
if (err != 0) {
fprintf(stderr, "Error creating ip address change notification thread.\n");
goto bail;
}
return (true);
bail:
close(ip_address_change_notification_socket);
ip_address_change_notification_socket = -1;
ip_address_change_notification_callback = NULL;
ip_address_change_notification_callback_userdata = NULL;
return false;
}
void end_ip_address_change_notifications(void)
{
if (ip_address_change_notification_socket == -1) return;
pthread_cancel(ip_address_change_notification_thread);
close(ip_address_change_notification_socket);
ip_address_change_notification_socket = -1;
ip_address_change_notification_callback = NULL;
ip_address_change_notification_callback_userdata = NULL;
}