linux icmp 源码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/ip_icmp.h>

unsigned short calculate_checksum(unsigned short *buffer, int size) {
    unsigned long checksum = 0;
    while (size > 1) {
        checksum += *buffer++;
        size -= sizeof(unsigned short);
    }
    if (size) {
        checksum += *(unsigned char *)buffer;
    }
    checksum = (checksum >> 16) + (checksum & 0xffff);
    checksum += (checksum >> 16);
    return (unsigned short)(~checksum);
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <hostname/IP>\n", argv[0]);
        return 1;
    }

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

    struct sockaddr_in dest_addr;
    memset(&dest_addr, 0, sizeof(dest_addr));
    dest_addr.sin_family = AF_INET;
    inet_pton(AF_INET, argv[1], &dest_addr.sin_addr);

    char sendbuf[1500];
    struct icmp *icmp = (struct icmp *)sendbuf;
    icmp->icmp_type = ICMP_ECHO;
    icmp->icmp_code = 0;
    icmp->icmp_cksum = 0;
    icmp->icmp_id = getpid();
    icmp->icmp_seq = 0;

    memset(sendbuf + sizeof(struct icmp), 0, 56);
    icmp->icmp_cksum = calculate_checksum((unsigned short *)icmp, sizeof(sendbuf));

    if (sendto(sockfd, sendbuf, sizeof(sendbuf), 0, (struct sockaddr *)&dest_addr, sizeof(dest_addr)) <= 0) {
        perror("sendto");
        close(sockfd);
        return 1;
    }

    printf("Ping request sent to %s\n", argv[1]);
    close(sockfd);
    return 0;
}