Linux下Ping的实现代码
Linux下Ping的实现代码:
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#define PACKET_SIZE 4096
#define ERROR 0
#define SUCCESS 1
// 效验算法
unsigned short cal_chksum(unsigned short *addr, int len)
{
int nleft=len;
int sum=0;
unsigned short *w=addr;
unsigned short answer=0;
while(nleft > 1)
{
sum += *w++;
nleft -= 2;
}
if( nleft == 1)
{
*(unsigned char *)(&answer) = *(unsigned char *)w;
sum += answer;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return answer;
}
// Ping函数
int ping( char *ips, int timeout)
{
struct timeval timeo;
int sockfd;
struct sockaddr_in addr;
struct sockaddr_in from;
struct timeval *tval;
struct ip *iph;
struct icmp *icmp;
char sendpacket[PACKET_SIZE];
char recvpacket[PACKET_SIZE];
int n;
pid_t pid;
int maxfds = 0;
fd_set readfds;
// 设定Ip信息
bzero(&addr,sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr(ips);
// 取得socket
sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
if (sockfd < 0)
{
syslog(LOG_INFO,"ip:%s,socket error",ips);
return ERROR;
}
// 设定TimeOut时间
timeo.tv_sec = timeout / 1000;
timeo.tv_usec = timeout % 1000;
if (setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo)) == -1)
{
syslog(LOG_INFO,"ip:%s,setsockopt error",ips);
return ERROR;
}
// 设定Ping包
memset(sendpacket, 0, sizeof(sendpacket));
// 取得PID,作为Ping的Sequence ID
pid=getpid();
int i,packsize;
icmp=(struct icmp*)sendpacket;
icmp->icmp_type=ICMP_ECHO;
icmp->icmp_code=0;
icmp->icmp_cksum=0;
icmp->icmp_seq=0;
icmp->icmp_id=pid;
packsize=8+56;
tval= (struct timeval *)icmp->icmp_data;
gettimeofday(tval,NULL);
icmp->icmp_cksum=cal_chksum((unsigned short *)icmp,packsize);
// 发包
n = sendto(sockfd, (char *)&sendpacket, packsize, 0, (struct sockaddr *)&addr, sizeof(addr));
if (n < 1)
{
syslog(LOG_INFO,"ip:%s,sendto error",ips);
return ERROR;
}
// 接受
// 由于可能接受到其他Ping的应答消息,所以这里要用循环
while(1)
{
// 设定TimeOut时间,这次才是真正起作用的
FD_ZERO(&readfds);
FD_SET(sockfd, &readfds);
maxfds = sockfd + 1;
n = select(maxfds, &readfds, NULL, NULL, &timeo);
if (n <= 0)
{
syslog(LOG_INFO,"ip:%s,Time out error",ips);
close(sockfd);
return ERROR;
}
// 接受
memset(recvpacket, 0, sizeof(recvpacket));
int fromlen = sizeof(from);
n = recvfrom(sockfd, recvpacket, sizeof(recvpacket), 0, (struct sockaddr *)&from, &fromlen);
if (n < 1) {
break;
}
// 判断是否是自己Ping的回复
char *from_ip = (char *)inet_ntoa(from.sin_addr);
syslog(LOG_INFO,"fomr ip:%s",from_ip);
if (strcmp(from_ip,ips) != 0)
{
syslog(LOG_INFO,"ip:%s,Ip wang",ips);
break;
}
iph = (struct ip *)recvpacket;
icmp=(struct icmp *)(recvpacket + (iph->ip_hl<<2));
syslog(LOG_INFO,"ip:%s,icmp->icmp_type:%d,icmp->icmp_id:%d",ips,icmp->icmp_type,icmp->icmp_id);
// 判断Ping回复包的状态
if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == pid)
{
// 正常就退出循环
break;
}
else
{
// 否则继续等
continue;
}
}
// 关闭socket
close(sockfd);
syslog(LOG_INFO,"ip:%s,Success",ips);
return SUCCESS;
}