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。