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#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define PACKET_SIZE 4096 
#define MAX_WAIT_TIME 5 
#define MAX_NO_PACKETS 3 

char sendpacket[PACKET_SIZE]; 
char recvpacket[PACKET_SIZE]; 
int sockfd,datalen=56; 
int nsend=0,nreceived=0; 
struct sockaddr_in dest_addr; 
pid_t pid; 
struct sockaddr_in from; 
struct timeval tvrecv; 

void statistics(int signo); 
unsigned short cal_chksum(unsigned short *addr,int len); 
int pack(int pack_no); 
void send_packet(void); 
void recv_packet(void); 
int unpack(char *buf,int len); 
void tv_sub(struct timeval *out,struct timeval *in); 

void statistics(int signo) 
{ printf("\n--------------------PING statistics-------------------\n"); 
printf("%d packets transmitted, %d received , %%%d lost\n",nsend,nreceived, 
(nsend-nreceived)/nsend*100); 
close(sockfd); 
exit(1); 
} 

/*УÑéºÍËã·¨*/ 
unsigned short cal_chksum(unsigned short *addr,int len) 
{ int nleft=len; 
int sum=0; 
unsigned short *w=addr; 
unsigned short answer=0; 

/*°ÑICMP±¨Í·¶þ½øÖÆÊý¾ÝÒÔ2×Ö½ÚΪµ¥Î»ÀÛ¼ÓÆðÀ´*/ 
while(nleft>1) 
{ sum+=*w++; 
nleft-=2; 
} 

/*ÈôICMP±¨Í·ÎªÆæÊý¸ö×Ö½Ú£¬»áÊ£ÏÂ×îºóÒ»×Ö½Ú¡£°Ñ×îºóÒ»¸ö×Ö½ÚÊÓΪһ¸ö2×Ö½ÚÊý¾ÝµÄ¸ß×Ö½Ú£¬Õâ¸ö2×Ö½ÚÊý¾ÝµÄµÍ×Ö½ÚΪ0£¬¼ÌÐøÀÛ¼Ó*/ 
if( nleft==1) 
{ *(unsigned char *)(&answer)=*(unsigned char *)w; 
sum+=answer; 
} 
sum=(sum>>16)+(sum&0xffff); 
sum+=(sum>>16); 
answer=~sum; 
return answer; 
} 

/*ÉèÖÃICMP±¨Í·*/ 
int pack(int pack_no) 
{ int i,packsize; 
struct icmp *icmp; 
struct timeval *tval; 

icmp=(struct icmp*)sendpacket; 
icmp->icmp_type=ICMP_ECHO; 
icmp->icmp_code=0; 
icmp->icmp_cksum=0; 
icmp->icmp_seq=pack_no; 
icmp->icmp_id=pid; 
packsize=8+datalen; 
tval= (struct timeval *)icmp->icmp_data; 
gettimeofday(tval,NULL); /*¼Ç¼·¢ËÍʱ¼ä*/ 
icmp->icmp_cksum=cal_chksum( (unsigned short *)icmp,packsize); /*УÑéËã·¨*/ 
return packsize; 
}

/*·¢ËÍÈý¸öICMP±¨ÎÄ*/ 
void send_packet() 
{ int packetsize; 
while( nsend<max_no_packets)
{ nsend++; 
packetsize=pack(nsend); /*ÉèÖÃICMP±¨Í·*/ 
if( sendto(sockfd,sendpacket,packetsize,0, 
(struct sockaddr *)&dest_addr,sizeof(dest_addr) )<0 ) 
{ perror("sendto error"); 
continue; 
} 
sleep(1); /*ÿ¸ôÒ»Ãë·¢ËÍÒ»¸öICMP±¨ÎÄ*/ 
} 
} 

/*½ÓÊÕËùÓÐICMP±¨ÎÄ*/ 
void recv_packet() 
{ int n,fromlen; 
extern int errno; 

signal(SIGALRM,statistics); 
fromlen=sizeof(from); 
while( nreceived<nsend)
{ alarm(MAX_WAIT_TIME); 
if( (n=recvfrom(sockfd,recvpacket,sizeof(recvpacket),0, 
(struct sockaddr *)&from,&fromlen)) <0) 
{ if(errno==EINTR)continue; 
perror("recvfrom error"); 
continue; 
} 
gettimeofday(&tvrecv,NULL); /*¼Ç¼½ÓÊÕʱ¼ä*/ 
if(unpack(recvpacket,n)==-1)continue; 
nreceived++; 
} 
} 

/*°þÈ¥ICMP±¨Í·*/ 
int unpack(char *buf,int len) 
{ int i,iphdrlen; 
struct ip *ip; 
struct icmp *icmp; 
struct timeval *tvsend; 
double rtt; 

ip=(struct ip *)buf; 
iphdrlen=ip->ip_hl<<2; /*Çóip±¨Í·³¤¶È,¼´ip±¨Í·µÄ³¤¶È±êÖ¾³Ë4*/ 
icmp=(struct icmp *)(buf+iphdrlen); /*Ô½¹ýip±¨Í·,Ö¸ÏòICMP±¨Í·*/ 
len-=iphdrlen; /*ICMP±¨Í·¼°ICMPÊý¾Ý±¨µÄ×ܳ¤¶È*/ 
if( len<8) /*СÓÚICMP±¨Í·³¤¶ÈÔò²»ºÏÀí*/ 
{ printf("ICMP packets\'s length is less than 8\n"); 
return -1; 
} 

/*È·±£Ëù½ÓÊÕµÄÊÇÎÒËù·¢µÄµÄICMPµÄ»ØÓ¦*/ 
if( (icmp->icmp_type==ICMP_ECHOREPLY) && (icmp->icmp_id==pid) ) 
{ tvsend=(struct timeval *)icmp->icmp_data; 
tv_sub(&tvrecv,tvsend); /*½ÓÊպͷ¢Ë͵Äʱ¼ä²î*/ 
rtt=tvrecv.tv_sec*1000+tvrecv.tv_usec/1000; /*ÒÔºÁÃëΪµ¥Î»¼ÆËãrtt*/ 

/*ÏÔʾÏà¹ØÐÅÏ¢*/ 
printf("%d byte from %s: icmp_seq=%u ttl=%d rtt=%.3f ms\n", 
len, 
inet_ntoa(from.sin_addr), 
icmp->icmp_seq, 
ip->ip_ttl, 
rtt); 
} 
else return -1; 
} 

main(int argc,char *argv[]) 
{ struct hostent *host; 
struct protoent *protocol; 
unsigned long inaddr=0l; 
int waittime=MAX_WAIT_TIME; 
int size=50*1024; 

if(argc<2) 
{ printf("usage:%s hostname/IP address\n",argv[0]); 
exit(1); 
} 

if( (protocol=getprotobyname("icmp") )==NULL) 
{ perror("getprotobyname"); 
exit(1); 
} 

/*Éú³ÉʹÓÃICMPµÄԭʼÌ×½Ó×Ö,ÕâÖÖÌ×½Ó×ÖÖ»ÓÐroot²ÅÄÜÉú³É*/
if( (sockfd=socket(AF_INET,SOCK_RAW,protocol->p_proto) )<0) 
{ perror("socket error"); 
exit(1); 
} 

/* »ØÊÕrootȨÏÞ,ÉèÖõ±Ç°Óû§È¨ÏÞ*/ 
setuid(getuid()); 

/*À©´óÌ×½Ó×Ö½ÓÊÕ»º³åÇøµ½50KÕâÑù×öÖ÷ҪΪÁ˼õС½ÓÊÕ»º³åÇøÒç³öµÄ 
µÄ¿ÉÄÜÐÔ,ÈôÎÞÒâÖÐpingÒ»¸ö¹ã²¥µØÖ·»ò¶à²¥µØÖ·,½«»áÒýÀ´´óÁ¿Ó¦´ð*/ 
setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size) ); 
bzero(&dest_addr,sizeof(dest_addr)); 
dest_addr.sin_family=AF_INET; 

/*ÅжÏÊÇÖ÷»úÃû»¹ÊÇipµØÖ·*/ 
if( inaddr=inet_addr(argv[1])==INADDR_NONE) 
{ if((host=gethostbyname(argv[1]) )==NULL) /*ÊÇÖ÷»úÃû*/ 
{ perror("gethostbyname error"); 
exit(1); 
} 
memcpy( (char *)&dest_addr.sin_addr,host->h_addr,host->h_length); 
} 
else /*ÊÇipµØÖ·*/ 
memcpy( (char *)&dest_addr,(char *)&inaddr,host->h_length); 
/*»ñÈ¡mainµÄ½ø³Ìid,ÓÃÓÚÉèÖÃICMPµÄ±êÖ¾·û*/ 
pid=getpid(); 
printf("PING %s(%s): %d bytes data in ICMP packets.\n",argv[1], 
inet_ntoa(dest_addr.sin_addr),datalen); 
send_packet(); /*·¢ËÍËùÓÐICMP±¨ÎÄ*/ 
recv_packet(); /*½ÓÊÕËùÓÐICMP±¨ÎÄ*/ 
statistics(SIGALRM); /*½øÐÐͳ¼Æ*/ 
return 0; 
} 

/*Á½¸ötimeval½á¹¹Ïà¼õ*/ 
void tv_sub(struct timeval *out,struct timeval *in) 
{ if( (out->tv_usec-=in->tv_usec)<0) 
{ --out->tv_sec; 
out->tv_usec+=1000000; 
} 
out->tv_sec-=in->tv_sec; 
}