如何在RAW套接字的缓冲区中提取数据包？

Question

我正在使用 RAW 套接字发送 ARP 数据包。这是代码：

#include <iostream>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <linux/if_ether.h>
#include <arpa/inet.h>
#include <stdio.h>

using namespace std;

uint16_t hard_type = 1;
uint16_t proto_type = 0x0800;
uint16_t op_code = 1;

struct sockaddr_in socket_address;

struct arp_header{
  uint16_t hardware_type = htons(hard_type);
  uint16_t protocol_type = htons(proto_type);
  uint8_t hardware_length = 6;
  uint8_t protocol_length = 4;
  uint16_t opcode = htons(op_code);
  uint8_t sender_hardware_address[6] = {0x00,0x45,0xe2,0x7a,0x01,0x53};
  uint32_t sender_protocol_address;
  uint8_t target_hadrware_address[6] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
  uint32_t target_protocol_address;
}arp_req;

void ipv4_address_assign(){
   const char *source_ipv4 = "192.168.1.7";
   const char *dest_ipv4 = "192.168.1.1";

   uint32_t src_ip_ver_4;
   uint32_t dst_ip_ver_4;

   inet_pton(AF_INET,source_ipv4,&src_ip_ver_4);
   inet_pton(AF_INET,dest_ipv4,&dst_ip_ver_4);

   arp_req.sender_protocol_address = htonl(src_ip_ver_4);
   arp_req.target_protocol_address = htonl(dst_ip_ver_4);
}

int main() {
    int sockfd = socket(AF_PACKET,SOCK_RAW,htons(ETH_P_ALL));
    if (sockfd == -1) {
       cout << "Cannot open socket"<< endl;
       return 0;
    }
    ipv4_address_assign();
    sendto(sockfd,&arp_req,sizeof arp_req,0,(struct sockaddr*)&socket_address,sizeof socket_address);

    char buffer[sizeof arp_req];

    socklen_t len = sizeof arp_req;

    cout<<"Waiting For Arp Packet"<<endl;
    recvfrom(sockfd,buffer,sizeof arp_req,0,(struct sockaddr*)&socket_address,&len);
    cout<<"Arp Packet Have Been Receive"<<endl;
    return 0;
}

我使用Wireshark查看数据包发送情况是否良好，结果没有问题，而且我还在Wireshark中看到了ARP响应，这是我想要的。

但问题是如何在监视器中以十六进制形式显示标头，甚至提取一些信息并将其存储在某个变量中，而且我还应该需要将其从网络字节顺序转换为主机字节顺序，但如何做到这一点？

Answer 1

这是输出缓冲区值的方法：

#include <array>
#include <iostream>
#include <format>

int main()
{
    std::array<std::uint8_t,8> values{0,1,2,3,11,12,13,15};
    for(const auto byte : values ) std::cout << std::format("{:02X} ",byte);
}

输出将是：

00 01 02 03 0B 0C 0D 0F