在SOCK_ RAW通信中创建以太网帧

我做了一个简单的ping程序，因为我创建了一个缓冲区，并且只有我填充了IP frame和icmp stucture。当我运行该程序时，它正常工作。

我查看了Wireshark中的执行情况，以太网帧已正确包含在echo请求，目标MAC地址正确(MAC可能在arp缓存中找到)，但以太网帧已自动创建，即使我没有将其填充到sock_raw套接字通信中使用的缓冲区中。

另一个问题是，我的朋友尝试了相同的代码，但当他在以太网头中签入Wireshark时，MAC地址是00.00.00.00.00，这意味着它将发送到每个设备，具有正确IP的相应设备将回复，但我的不是这样

代码在这里

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUFFER_SIZE 100
#define DEFAULT_NUM_PACKETS 10
char buf[BUFFER_SIZE]; 
char *message = "n ./output_file <sender_ip_addr> <dest_ip_addr> <no_of_reqs>n 
<no_of_req> = is the number of requests to send and 10 is the default and mentioning 0  is infiniten";
void set_ip_layer_fields(struct icmphdr *icmp, struct ip *ip)
{
// IP layer
ip->ip_v = 4;
ip->ip_hl = sizeof*ip >> 2;
ip->ip_tos = 0;
ip->ip_len = htons(sizeof(buf));
ip->ip_id = 0;
ip->ip_off = 0;
ip->ip_ttl = 255;
ip->ip_p = 1;
ip->ip_sum = 0; 
// ICMP Layer
icmp->type = 8;
icmp->code = 0;     
icmp->checksum = htons(~(ICMP_ECHO << 8));  
}
int main(int argc, char *argv[])
{
int s, i ;  
struct ip *ip = (struct ip *)buf;
struct icmphdr *icmp = (struct icmphdr *)(ip + 1);
struct hostent *hp, *hp2;
struct sockaddr_in dst;                               
int num = DEFAULT_NUM_PACKETS;
if(argc < 3)
{
fprintf(stdout, "%sn",message);
exit(1);
}
// If enough arguments supplied 
if(argc == 4)
num = atoi(argv[3]);
// Loop based on the no of requests
for(i = 1; num == 0 ? num == 0 : i <= num; i++)
{
memset(buf, 0, sizeof(buf));
if((s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0)
{
perror("socket() error");
exit(1);
}
if((hp = gethostbyname(argv[2])) == NULL)
{
if((ip->ip_dst.s_addr = inet_addr(argv[2])) == -1)
{
fprintf(stderr, "%s: unknown host.n", argv[2]);
exit(1);
}
}
else
memcpy(&ip->ip_dst.s_addr, hp->h_addr_list[0], hp->h_length);
if((hp2 = gethostbyname(argv[1])) == NULL)
{
if((ip->ip_src.s_addr = inet_addr(argv[1])) == -1)
{
fprintf(stderr, "%s: unknown hostn", argv[1]);
exit(1);
}
}
else
memcpy(&ip->ip_src.s_addr, hp2->h_addr_list[0], hp->h_length);
set_ip_layer_fields(icmp, ip);
dst.sin_addr = ip->ip_dst;
dst.sin_family = AF_INET;
if(sendto(s, buf, sizeof(buf), 0, (struct sockaddr *)&dst, sizeof(dst)) < 0)
{
fprintf(stderr, "error while sendingn");
}
else
printf("request:%d sended successfullyn",i);
close(s);
}
return 0;
}