C++ Socket庫(kù)處理ICMP消息

在C++中，處理ICMP消息通常需要使用原始套接字（raw socket）

#include <iostream>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/icmp.h>
#include <unistd.h>
#include <cstring>

#define ICMP_BUFFER_SIZE 1500

int main(int argc, char *argv[]) {
    if (argc != 2) {
        std::cerr << "Usage: " << argv[0]<< " <ICMP_message>" << std::endl;
        return 1;
    }

    int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
    if (sockfd < 0) {
        perror("socket");
        return 1;
    }

    struct sockaddr_in icmp_addr;
    memset(&icmp_addr, 0, sizeof(icmp_addr));
    icmp_addr.sin_family = AF_INET;
    icmp_addr.sin_port = htons(0);
    icmp_addr.sin_addr.s_addr = inet_addr(argv[1]);

    struct icmp *icmp_header = (struct icmp *)argv[1];
    if (sendto(sockfd, icmp_header, ICMP_BUFFER_SIZE, 0, (struct sockaddr *)&icmp_addr, sizeof(icmp_addr)) < 0) {
        perror("sendto");
        close(sockfd);
        return 1;
    }

    close(sockfd);
    return 0;
}

要編譯此程序，請(qǐng)使用以下命令：

g++ -o icmp_sender icmp_sender.cpp

然后，你可以使用以下命令發(fā)送ICMP Echo請(qǐng)求（ping）：

sudo ./icmp_sender <destination_ip>

請(qǐng)注意，運(yùn)行此程序可能需要管理員權(quán)限，因?yàn)樗枰獎(jiǎng)?chuàng)建原始套接字。

要處理收到的ICMP消息，你需要編寫(xiě)一個(gè)循環(huán)來(lái)接收數(shù)據(jù)包，然后解析ICMP頭。這涉及到檢查ICMP類(lèi)型和代碼字段，以及獲取相關(guān)的數(shù)據(jù)包信息（如源IP和目標(biāo)IP）。這里有一個(gè)簡(jiǎn)單的示例，展示了如何接收和解析ICMP Echo請(qǐng)求（ping響應(yīng)）：

#include <iostream>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/icmp.h>
#include <unistd.h>
#include <cstring>

#define BUF_SIZE 1500

int main(int argc, char *argv[]) {
    if (argc != 2) {
        std::cerr << "Usage: " << argv[0]<< " <port>" << std::endl;
        return 1;
    }

    int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
    if (sockfd < 0) {
        perror("socket");
        return 1;
    }

    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(argv[1]));
    serv_addr.sin_addr.s_addr = INADDR_ANY;

    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("bind");
        close(sockfd);
        return 1;
    }

    struct sockaddr_in from;
    socklen_t from_size = sizeof(from);
    char buffer[BUF_SIZE];

    while (1) {
        int n = recvfrom(sockfd, buffer, BUF_SIZE, 0, (struct sockaddr *)&from, &from_size);
        if (n < 0) {
            perror("recvfrom");
            continue;
        }

        struct icmp *icmp_header = (struct icmp *)(buffer + 20); // Skip Ethernet header
        if (icmp_header->icmp_type == ICMP_ECHO && icmp_header->icmp_code == 0) {
            std::cout << "Received ICMP Echo reply from " << inet_ntoa(from.sin_addr) << std::endl;
        }
    }

    close(sockfd);
    return 0;
}

要編譯此程序，請(qǐng)使用以下命令：

g++ -o icmp_receiver icmp_receiver.cpp

然后，你可以使用以下命令運(yùn)行此程序并監(jiān)聽(tīng)指定的端口：

sudo ./icmp_receiver <port>

請(qǐng)注意，運(yùn)行此程序可能需要管理員權(quán)限，因?yàn)樗枰獎(jiǎng)?chuàng)建原始套接字。