xdp-ebpf multicast unknown protocol in ethernet header

Question

Below are the sample codes

    struct ethhdr {
    unsigned char   h_dest[ETH_ALEN];   /* destination eth addr */
    unsigned char   h_source[ETH_ALEN]; /* source ether addr    */
    __be16      h_proto;        /* packet type ID field */
} __attribute__((packed));

xdp_kernel.c

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>

#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/in.h>


SEC("xdp")
int xdp_test(struct xdp_md *ctx)
{
    bpf_printk("PACKET RECIEVED");
    void *data_end = (void *)(long)ctx->data_end;
    void *data = (void *)(long)ctx->data;

    void *pos = data;
    struct ethhdr *eth = (struct ethhdr *)(pos);

    if ((eth + 1) <= data_end)
    {
        bpf_printk("ETH %ld 0x%X",data_end-data,bpf_ntohs(eth->h_proto));
        if (bpf_ntohs(eth->h_proto) == ETH_P_IP)
        {
            //bpf_printk("IP");
            pos += sizeof(struct ethhdr);
            struct iphdr *iph = (struct iphdr *)(pos);

            if ((iph + 1) <= data_end)
            {
                if (iph->protocol == IPPROTO_UDP)
                {
                    bpf_printk("UDP");
                    const __u16 iph_sz_in_bytes = iph->ihl * 4;

                    if (((void *)iph + iph_sz_in_bytes) <= data_end)
                    {
                        pos += iph_sz_in_bytes;

                        struct udphdr *udh = (struct udphdr *)(pos);

                        if ((udh + 1) <= data_end)
                        {
                        }
                    }
                }
            }
        }
    }
    return XDP_PASS;
}

char _license[] SEC("license") = "GPL";

sender.c

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

int main()
{
    const int delay_secs = 1;
    const char *message2 = "Hello, World!";

    unsigned long counter = 0;

    char message[8192] = {0};

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

    struct ip_mreq mreq;
    memset(&mreq, 0, sizeof(mreq));
    mreq.imr_interface.s_addr = inet_addr("192.168.2.6"); // local wifi interface address

    if (
        setsockopt(
            fd, IPPROTO_IP, IP_MULTICAST_IF, (char *)&mreq, sizeof(mreq)) < 0)
    {
        perror("setsockopt");
        return 1;
    }

    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("239.0.0.0");
    addr.sin_port = htons(1234);

    while (1)
    {
        char ch = 0;
        snprintf(message, 8192, "%s-%lu", message2, ++counter);
        int nbytes = sendto(
            fd,
            message,
            strlen(message),
            0,
            (struct sockaddr *)&addr,
            sizeof(addr));
        if (nbytes < 0)
        {
            perror("sendto");
            return 1;
        }
        sleep(delay_secs);
    }

    return 0;
}

listner.c

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define MSGBUFSIZE 8192

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

    u_int yes = 1;
    if (
        setsockopt(
            fd, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof(yes)) < 0)
    {
        perror("Reusing ADDR failed");
        return 1;
    }

    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("239.0.0.0"); 
    addr.sin_port = htons(1234);

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

    struct ip_mreq mreq;
    mreq.imr_multiaddr.s_addr = inet_addr("239.0.0.0");
    mreq.imr_interface.s_addr = inet_addr("192.168.2.6"); //local wifi address
    if (
        setsockopt(
            fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&mreq, sizeof(mreq)) < 0)
    {
        perror("setsockopt");
        return 1;
    }

    while (1)
    {
        char msgbuf[MSGBUFSIZE];
        int addrlen = sizeof(addr);
        int nbytes = recvfrom(
            fd,
            msgbuf,
            MSGBUFSIZE,
            0,
            (struct sockaddr *)&addr,
            &addrlen);
        if (nbytes < 0)
        {
            perror("recvfrom");
            return 1;
        }
        msgbuf[nbytes] = '\0';
        puts(msgbuf);
    }

    return 0;
}

sender is sending multicast successfully and even listener is receiving

Issue here in in XDP kernel code am not able to capture this packet since i am only interested in IP4 protocol,but trace in XDP prints the below protocol ID

sender-28811 [002] ..s21 11044.326101: bpf_trace_printk: PACKET RECIEVED

sender-28811 [002] ..s21 11044.326122: bpf_trace_printk: ETH 45 0xC0A8

Where as for other IP4 it prints

irq/168-iwlwifi-596 [006] ..s21 11041.649288: bpf_trace_printk: PACKET RECIEVED

irq/168-iwlwifi-596 [006] ..s21 11041.649298: bpf_trace_printk: ETH 60 0x800

what might be the issue here.

Also any way can i print h_dest(MAC address)