#include?
#include?
#include?
#include?
#include?“ping.h“

#define?ICMP_ECHOREPLY?0
#define?ICMP_ECHOREQ?8

//?statistics
int?nsend?=?0?nrecv?=?0;
int?rrt[10];
int?packsize;

void?get_data（int?rrt[]?int?size?int?*min?int?*max?int?*avg）;
void?tv_sub（struct?timeval?*outstruct?timeval?*in）;

//?calculate?checksum?of?icmp?header
uint16_t?cal_cksum（uint16_t?*addr?int?len）
{
	int?nleft?=?len;
	uint32_t?sum?=?0;
	uint16_t?*w?=?addr;
	uint16_t?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）;
}

void?print_head（char?*ip）
{
	packsize?=?sizeof（struct?icmp）?+?sizeof（struct?timeval）;
	printf（“Ping?%s?with?%d?bytes?of?data:\n“?ip?packsize）;
}

void?print_stat（char?*ip）
{
	int?min_rrt?max_rrt?avg_rrt;
	int?lost;
	
	if（nsend?		return;
	get_data（rrt?nsend?&min_rrt?&max_rrt?&avg_rrt）;

	lost?=?nsend?-?nrecv;
	printf（“========================================================================\n“）;
	printf（“Ping?Statistics?for?%s:\n“?ip）;
	printf（“\tPackets:?Send?=?%d?Received?=?%d?Lost?=?%d（%.1f%%?lost）\n“?nsend?nrecv?lost?（lost?/?（nsend?*?1.0）?*?100.0））;
	printf（“Approximate?round?trip?times?in?milli-seconds:\n“）;
	printf（“\tMinimum?=?%dms?Maximum?=?%dms?Average?=?%dms\n“?min_rrt?max_rrt?avg_rrt）;
}

void?send_ping（int?sockfd?struct?sockaddr_in?*dstaddr）
{
	char?buf[100];
	size_t?len?=?sizeof（struct?icmp）;
	socklen_t?dstlen?=?sizeof（struct?sockaddr_in）;
	struct?icmp?*echo;

	memset（buf?0?sizeof（buf））;
	echo?=?（struct?icmp*）buf;
	echo?=?（struct?icmp?*）buf;
	echo->icmp_type?=?ICMP_ECHOREQ;
	echo->icmp_code?=?0;
	echo->icmp_cksum?=?0;
	echo->icmp_id?=?getpid（）;
	echo->icmp_seq?=?nsend;
	struct?timeval?*tval=?（struct?timeval?*）echo->icmp_data;
	gettimeofday（tvalNULL）;
	echo->icmp_cksum?=?cal_cksum（（uint16_t?*）echo?packsize）;

	//?send?ping?message
	if（sendto（sockfd?buf?len?0?（struct?sockaddr*）dstaddr?dstlen）?==?-1）
		printf（“Send?Ping?Message?Error!\n“）;
	
	nsend++;
}

void?recv_ping（int?sockfd?struct?sockaddr_in?*dstaddr）
{
	char?buf[100];
	ssize_t?n;
	struct?ip?*ip;
	struct?icmp?*icmp;
	socklen_t?dstlen?=?sizeof（struct?sockaddr_in）;
	int?ttl;
	fd_set?rset;
	int?maxfd?=?sockfd?+?1;
	struct?timeval?timeo?*tvsend?tvrecv;
	unsigned?char?*p;
	unsigned?char?ipaddr[100];
	int?time;

	memset（buf?0?sizeof（buf））;
	timeo.tv_sec?=?3;
	timeo.tv_usec?=?0;
	
	FD_ZERO（&rset）;
	FD_SET（sockfd?&rset）;
	
	
	while（1）
	{
		//?set?timeout?3s
		if（（n?=?select（maxfd?&rset?NULL?NULL?&timeo））?==?-1）
		{
			printf（“Select?Error!\n“）;
			exit（1）;
		}

		if（n?<=?0）
		{
			printf（“Request?Time?Out!\n“）;
			fflush（stdout）;
			break;
		}
		
		
		if（（n?=?recvfrom（sockfd?buf?