C++实现ICMP时间戳请求的方法

在C++中，使用原始套接字（raw socket）实现ICMP时间戳请求需要以下几个步骤：

1. 包含必要的头文件。
2. 创建一个原始套接字。
3. 构造ICMP时间戳请求数据包。
4. 发送数据包。
5. 接收响应。
6. 解析响应并提取时间戳。
7. 关闭套接字。

以下是一个简单的示例代码：

#include<iostream> #include <cstring> #include <unistd.h> #include <arpa/inet.h> #include <netinet/ip.h> #include <netinet/ip_icmp.h> #include <sys/socket.h> #include <sys/types.h>  const int ICMP_TIMESTAMP_REQUEST = 13; const int ICMP_TIMESTAMP_REPLY = 14;  struct icmp_timestamp {     uint8_t type;     uint8_t code;     uint16_t checksum;     uint16_t id;     uint16_t seq;     uint32_t originate_timestamp;     uint32_t receive_timestamp;     uint32_t transmit_timestamp; };  uint16_t calculate_checksum(icmp_timestamp *icmp) {     uint32_t sum = 0;     uint16_t *buf = (uint16_t *)icmp;     uint16_t size = sizeof(icmp_timestamp);      while (size > 1) {         sum += *(buf++);         size -= 2;     }      if (size) {         sum += *(uint8_t *)buf;     }      while (sum >> 16) {         sum = (sum & 0xffff) + (sum >> 16);     }      return (uint16_t)(~sum); }  int main() {     int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);     if (sockfd == -1) {         std::cerr << "Failed to create raw socket"<< std::endl;         return 1;     }      struct sockaddr_in target;     memset(&target, 0, sizeof(target));     target.sin_family = AF_INET;     inet_pton(AF_INET, "8.8.8.8", &target.sin_addr); // Replace with the desired target IP address      icmp_timestamp request;     memset(&request, 0, sizeof(request));     request.type = ICMP_TIMESTAMP_REQUEST;     request.code = 0;     request.id = htons(getpid());     request.seq = htons(1);     request.originate_timestamp = htonl(time(nullptr));     request.checksum = calculate_checksum(&request);      if (sendto(sockfd, &request, sizeof(request), 0, (struct sockaddr *)&target, sizeof(target)) == -1) {         std::cerr << "Failed to send ICMP timestamp request"<< std::endl;         close(sockfd);         return 1;     }      char buffer[1024];     struct sockaddr_in source;     socklen_t source_len = sizeof(source);      ssize_t received = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)&source, &source_len);     if (received == -1) {         std::cerr << "Failed to receive ICMP timestamp reply"<< std::endl;         close(sockfd);         return 1;     }      icmp_timestamp *reply = (icmp_timestamp *)(buffer + sizeof(struct ip));     if (reply->type == ICMP_TIMESTAMP_REPLY) {         uint32_t transmit_timestamp = ntohl(reply->transmit_timestamp);         std::cout << "Received ICMP timestamp reply: "<< transmit_timestamp<< std::endl;     } else {         std::cerr << "Received unexpected ICMP message type: " << (int)reply->type<< std::endl;     }      close(sockfd);     return 0; } 

这个示例代码向目标IP地址（在这里是8.8.8.8，可以替换为任何其他有效的IP地址）发送一个ICMP时间戳请求，然后接收并解析响应以获取时间戳。注意，运行此代码可能需要root权限，因为创建原始套接字通常需要特权。