使用原始套接字完成网络数据包的封装和发送

程序目的：

       程序可用来封装特定的arp回应包。

       使用此程序主要用于网络调试目的和实验项目， 请勿非法使用。

       代码摘选了：原始套接字（网络编程再进阶）中的代码实现，为了更加灵活的使用，做了一些更改

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
int main(int argc, char** argv)
{
	struct _ipv4_arp_response {
		unsigned char target_mac[6];
		unsigned char source_mac[6];
		unsigned char protocal[2];

		unsigned char hardclass[2];
		unsigned char protocalclass[2];
		unsigned char hardlong;
		unsigned char protocallong;
		unsigned char opcode[2];
		unsigned char sendermac[6];
		unsigned char sendip[4];
		unsigned char recivermac[6];
		unsigned char reciverip[4];
	} ipv4_arp_response;
 
  unsigned char arp_buf[42] ={
    0x8C, 0xDE, 0xF9, 0xBF, 0x44, 0xCB,
    0x00, 0xF4, 0x8D, 0xA7, 0xFA, 0xFF,
    0x8,0x6,
    0x0,0x1,
    0x8,0x0,
    6,
    4,
    0x0,0x2,
    0x00, 0xF4, 0x8D, 0xA7, 0xFA, 0xFF,
    192, 168, 15, 30,
    0x8C, 0xDE, 0xF9, 0xBF, 0x44, 0xCB,
    192, 168, 15, 192};
  memcpy(&ipv4_arp_response,arp_buf,sizeof(arp_buf));
  int str[6];
  if(argc>2){
  	sscanf(argv[1], "%x:%x:%x:%x:%x:%x", &str[0], &str[1], &str[2], &str[3], &str[4], &str[5]);
  	sscanf(argv[2], "%u.%u.%u.%u", &ipv4_arp_response.sendip[0], &ipv4_arp_response.sendip[1], &ipv4_arp_response.sendip[2], &ipv4_arp_response.sendip[3]);
  	for (int i = 0; i < 6; ++i)
  	{
  		ipv4_arp_response.source_mac[i]=str[i];
        ipv4_arp_response.sendermac[i]=str[i];
  	}
   memcpy(arp_buf,&ipv4_arp_response,sizeof(arp_buf));
  }
  int sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
  
  //网卡结构体
  struct ifreq ethreq;
  strncpy(ethreq.ifr_ifrn.ifrn_name, "eth0", IFNAMSIZ);
  if(-1 == ioctl(sock_fd,SIOCGIFINDEX,ðreq))//获取网络接口
  {
      perror("ioctl");
  }
  struct sockaddr_ll add;
  bzero(&add, sizeof(add));

  add.sll_ifindex = ethreq.ifr_ifru.ifru_ivalue;//给add赋值

  int i = 0;
  while(1)
  {
      sleep(2);
      int len = sendto(sock_fd, arp_buf, sizeof(arp_buf), 0, (struct sockaddr *)&add, sizeof(add));
      i++;
      // printf("sendbyte:%d,%d\n", len,i);
  }
}