linux raw ethernet socket绑定到特定协议

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

#define BUF_SIZE 65536

int main(int argc, char *argv[]) {
    int sockfd;
    struct ifreq ifr;
    struct sockaddr_in sin;
    char buf[BUF_SIZE];

    if (argc != 3) {
        printf("Usage: %s<interface><protocol>\n", argv[0]);
        exit(1);
    }

    sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
    if (sockfd < 0) {
        perror("socket");
        exit(1);
    }

    strncpy(ifr.ifr_name, argv[1], IFNAMSIZ);
    if (ioctl(sockfd, SIOCGIFINDEX, &ifr) < 0) {
        perror("ioctl");
        exit(1);
    }

    sin.sin_family = AF_INET;
    sin.sin_port = htons(0);
    sin.sin_addr.s_addr = INADDR_ANY;

    if (bind(sockfd, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
        perror("bind");
        exit(1);
    }

    if (setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &(int){1}, sizeof(int)) < 0) {
        perror("setsockopt");
        exit(1);
    }

    while (1) {
        ssize_t len = recv(sockfd, buf, BUF_SIZE, 0);
        if (len < 0) {
            perror("recv");
            exit(1);
        }

        struct iphdr *iph = (struct iphdr *)buf;
        if (iph->protocol == atoi(argv[2])) {
            printf("Received packet with protocol %d\n", iph->protocol);
        }
    }

    close(sockfd);
    return 0;
}