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Linux ping c实现

news 来源：原创 2024/9/28 20:32:39

linux下ping程序的c实现

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdint.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <sys/time.h>
#include <errno.h>#define DATA_SIZE 32#define pri_debug printf
#define pri_error printftypedef struct tag_icmp_header
{u_int8_t  type;u_int8_t  code;u_int16_t check_sum;u_int16_t id;u_int16_t seq;
} icmp_header;typedef struct tag_iphdr
{u_int8_t        ip_head_verlen;u_int8_t        ip_tos;unsigned short  ip_length;unsigned short  ip_id;unsigned short  ip_flags;u_int8_t        ip_ttl;u_int8_t        ip_protacol;unsigned short  ip_checksum;int             ip_source;int             ip_destination;
} ip_header;unsigned short generation_checksum(unsigned short * buf, int size)
{unsigned long cksum = 0;while(size > 1){cksum += *buf++;size -= sizeof(unsigned short);}if(size){cksum += *buf++;}cksum =  (cksum>>16) + (cksum & 0xffff);cksum += (cksum>>16);return (unsigned short)(~cksum);
}double get_time_interval(struct timeval * start, struct timeval * end)
{double interval;struct timeval tp;tp.tv_sec = end->tv_sec - start->tv_sec;tp.tv_usec = end->tv_usec - start->tv_usec;if(tp.tv_usec < 0){tp.tv_sec -= 1;tp.tv_usec += 1000000;}interval = tp.tv_sec * 1000 + tp.tv_usec * 0.001;return interval;
}int ping_host_ip(const char * domain)
{int i;int ret = -1;int client_fd;int size = 50 * 1024;struct timeval timeout;char * icmp;in_addr_t dest_ip;icmp_header * icmp_head;struct sockaddr_in dest_socket_addr;if(domain == NULL){pri_debug("ping_host_ip domain is NULL!\n");return ret;}dest_ip = inet_addr(domain);if(dest_ip == INADDR_NONE){struct hostent* p_hostent = gethostbyname(domain);if(p_hostent){dest_ip = (*(in_addr_t*)p_hostent->h_addr);}}client_fd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);if (client_fd == -1){pri_error("socket error: %s!\n", strerror(errno));return ret;}timeout.tv_sec = 1;timeout.tv_usec = 0;setsockopt(client_fd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));if(setsockopt(client_fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(struct timeval))){pri_error("setsocketopt SO_RCVTIMEO error!\n");return ret;}if(setsockopt(client_fd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(struct timeval))){pri_error("setsockopt SO_SNDTIMEO error!\n");return ret;}dest_socket_addr.sin_family = AF_INET;dest_socket_addr.sin_addr.s_addr = dest_ip;dest_socket_addr.sin_port = htons(0);memset(dest_socket_addr.sin_zero, 0, sizeof(dest_socket_addr.sin_zero));icmp = (char *)malloc(sizeof(icmp_header) + DATA_SIZE);memset(icmp, 0, sizeof(icmp_header) + DATA_SIZE);icmp_head = (icmp_header *)icmp;icmp_head->type = 8;icmp_head->code = 0;icmp_head->id = 1;pri_debug("PING %s (%s).\n", domain, inet_ntoa(*((struct in_addr*)&dest_ip)));for(i = 0; i < 3; i++){struct timeval start;struct timeval end;long result;struct sockaddr_in from;socklen_t from_packet_len;long read_length;char recv_buf[1024];icmp_head->seq = htons(i);icmp_head->check_sum = 0;icmp_head->check_sum = generation_checksum((unsigned short*)icmp,sizeof(icmp_header) + DATA_SIZE);gettimeofday(&start, NULL);result = sendto(client_fd, icmp, sizeof(icmp_header) +DATA_SIZE, 0, (struct sockaddr *)&dest_socket_addr,sizeof(dest_socket_addr));if(result == -1){pri_debug("PING: sendto: Network is unreachable\n");continue;}from_packet_len = sizeof(from);memset(recv_buf, 0, sizeof(recv_buf));while(1){read_length = recvfrom(client_fd, recv_buf, 1024, 0,(struct sockaddr*)&from, &from_packet_len);gettimeofday( &end, NULL );if(read_length != -1){ip_header * recv_ip_header = (ip_header*)recv_buf;int ip_ttl = (int)recv_ip_header->ip_ttl;icmp_header * recv_icmp_header = (icmp_header *)(recv_buf +(recv_ip_header->ip_head_verlen & 0x0F) * 4);if(recv_icmp_header->type != 0){pri_error("error type %d received, error code %d \n", recv_icmp_header->type, recv_icmp_header->code);break;}if(recv_icmp_header->id != icmp_head->id){pri_error("some else's packet\n");break;}if(read_length >= (long)(sizeof(ip_header) +sizeof(icmp_header) + DATA_SIZE)){pri_debug("%ld bytes from %s (%s): icmp_seq=%d ttl=%d time=%.2f ms\n",read_length, domain, inet_ntoa(from.sin_addr), recv_icmp_header->seq / 256,ip_ttl, get_time_interval(&start, &end));ret = 0;// 证明网络通畅，后续的包已经不许再需要验证goto PING_EXIT;}break;}else{pri_error("receive data error!\n");break;}}}PING_EXIT:if(NULL != icmp){free(icmp);icmp = NULL;}if(client_fd != -1){close(client_fd);}return ret;
}int main(int argc, char **argv)
{ping_host_ip(argv[1]);
}