如何访问mBlk以太网包中的报头和数据信息？具体地说，我想提取一个发送者IP

#include <netinet/if_ether.h> // 以太网头文件
#include <netinet/ip.h> // IP头文件

struct ether_header *eth_hdr = (struct ether_header *)m->m_data;

printf("源MAC地址：%02x:%02x:%02x:%02x:%02x:%02x\n",
    eth_hdr->ether_shost[0], eth_hdr->ether_shost[1],
    eth_hdr->ether_shost[2], eth_hdr->ether_shost[3],
    eth_hdr->ether_shost[4], eth_hdr->ether_shost[5]);

struct ip *ip_hdr = (struct ip *)(m->m_data + sizeof(struct ether_header));

printf("发送者IP地址：%s\n", inet_ntoa(ip_hdr->ip_src));