linux netlink编程

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

#define NETLINK_USER 31

struct sockaddr_nl src_addr, dest_addr;
struct nlmsghdr *nlh = NULL;
struct iovec iov;
int sock_fd;
char buffer[65536];

void send_msg(char *msgbuf, int msg_len) {
    nlh->nlmsg_len = NLMSG_LENGTH(msg_len);
    memcpy(NLMSG_DATA(nlh), msgbuf, msg_len);
    iov.iov_base = (void *)nlh;
    iov.iov_len = nlh->nlmsg_len;
    sendmsg(sock_fd, &iov, 1);
}

void recv_msg() {
    int len, msg_len;
    struct nlmsghdr *nlh;

    len = recv(sock_fd, buffer, sizeof(buffer), 0);
    if (len < 0) {
        perror("recv");
        return;
    }

    nlh = (struct nlmsghdr *)buffer;
    while (NLMSG_OK(nlh, len)) {
        printf("Received message payload: %s\n", NLMSG_DATA(nlh));
        nlh = NLMSG_NEXT(nlh, len);
    }
}

int main() {
    sock_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_USER);
    if (sock_fd < 0) {
        perror("socket");
        return -1;
    }

    memset(&src_addr, 0, sizeof(src_addr));
    src_addr.nl_family = AF_NETLINK;
    src_addr.nl_pid = getpid();
    src_addr.nl_groups = 0;

    if (bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr)) < 0) {
        perror("bind");
        close(sock_fd);
        return -1;
    }

    memset(&dest_addr, 0, sizeof(dest_addr));
    dest_addr.nl_family = AF_NETLINK;
    dest_addr.nl_pid = 0; // For kernel
    dest_addr.nl_groups = 0;

    nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(sizeof(char)));
    memset(nlh, 0, NLMSG_SPACE(sizeof(char)));
    nlh->nlmsg_len = NLMSG_LENGTH(sizeof(char));
    nlh->nlmsg_pid = getpid();
    nlh->nlmsg_flags = 0;

    iov.iov_base = (void *)nlh;
    iov.iov_len = nlh->nlmsg_len;
    sendmsg(sock_fd, &iov, 1);

    recv_msg();

    close(sock_fd);
    return 0;
}