无法获得ICMP包裹的TOS和有效载荷

Question

我有以下代码来获取TOS和ICMP有效载荷：

typedef struct eth_hdr{
    u_char dst_mac[6];
    u_char src_mac[6];
    u_short eth_type;
}eth_hdr;
eth_hdr *ethernet;

typedef struct ip_hdr{
    int version:4;
    int header_len:4;
    u_char tos:8;
    int total_len:16;
    int ident:16;
    int flags:16;
    u_char ttl:8;
    u_char protocol:8;
    int checksum:16;
    u_char sourceIP[4];
    u_char destIP[4];
}ip_hdr;
ip_hdr *ip;

typedef struct icmp_header{
    u_int8_t icmp_type;
    u_int8_t icmp_code;
    u_int16_t icmp_checksum;
    u_int16_t icmp_id_j;
    u_int16_t icmp_sequence;
} icmp_header;
icmp_header *icmp_protocol;


void pcap_callback(unsigned char * arg,const struct pcap_pkthdr *packet_header,const unsigned char *packet_content){
    u_int eth_len=sizeof(struct eth_hdr);
    u_int ip_len=sizeof(struct ip_hdr);
    u_int icmp_len = sizeof(struct icmp_header);
    ethernet=(eth_hdr *)packet_content;

    if(ntohs(ethernet->eth_type)==0x0800){//ipv4
        ip=(ip_hdr*)(packet_content+eth_len);
        printf("--IP TOS:%s\n",ip->tos);
       if(ip->protocol==1){//icmp
            printf("icmp is used:\n");
            icmp_protocol = (icmp_header*)(packet_content+eth_len+ip_len);
            printf("ICMP Type:%c\n",icmp_protocol->icmp_type);
            printf("ICMP Code:%d\n",icmp_protocol->icmp_code);
        }else {
            printf("other transport protocol is used %d\n",ip->protocol);
        }
        u_char *payload = (u_char *)(packet_content+eth_len+ip_len+icmp_len);

        printf("--Print Payload:%s\n",payload);
    }else {
        printf("ipv6 is used\n");
    }
}

int main(int argc, char *argv[]){
    char *dev,errbuf[1024];
    dev="bond0";
    pcap_t *pcap_handle=pcap_open_live(dev,65535,1,0,errbuf);
    ipcap_loop(pcap_handle,-1,pcap_callback,NULL);
    pcap_close(pcap_handle);
    return 0;
}

我可以很好地获得SrcIP和DstIP，但是TOS总是空的（我确定路由器确实设置了Tos），而且我也无法获得ICMP有效负载数据。