|
;
void send_packet(void);
void recv_packet(void);
int unpack(char *buf,int len);
void tv_sub(struct timeva l *out,struct timeva l *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);
}
/*校验和算法*/
unsigned short cal_chksum(unsigned short *addr,int len)
{ int nleft=len;
int sum=0;
unsigned short *w=addr;
unsigned short answer=0;
/*把ICMP报头二进制数据以2字节为单位累加起来*/
while(nleft>1)
{ sum+=*w++;
nleft-=2;
}
/*若ICMP报头为奇数个字节，会剩下最后一字节。把最后一个字节视为一个2字节数据的高字节，这个2字节数据的低字节为0，继续累加*/
if( nleft==1)
{ *(unsigned char *)(&answer)=*(unsigned char *)w;
sum+=answer;
}
sum=(sum>>16)+(sum&0xffff);
sum+=(sum>>16);
answer=~sum;
return answer;
}
/*设置ICMP报头*/
int pack(int pack_no)
{ int i,packsize;
struct icmp *icmp;
struct timeva l *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 timeva l *)icmp->icmp_data;
gettimeofday(tval,NULL); /*记录发送时间*/
icmp->icmp_cksum=cal_chksum( (unsigned short *)icmp,packsize); /*校验算法*/
return packsize;
}
/*发送三个ICMP报文*/
void send_packet()
{ int packetsize;
while( nsend<MAX_NO_PACKETS)
{ nsend++;
packetsize=pack(nsend); /*设置ICMP报头*/
if( sendto(sockfd,sendpacket,packetsize,0,
(struct sockaddr *)&dest_addr,sizeof(dest_addr) )<0 )
{ perror("sendto error");
continue;
}
sleep(1); /*每隔一秒发送一个ICMP报文*/
}
}
/*接收所有ICMP报文*/
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); /*记录接收时间*/
if(unpack(recvpacket,n)==-1)continue;
nreceived++;
}
}
/*剥去ICMP报头*/
int unpack(char *buf,int len)
{ int i,iphdrlen;
struct ip *ip;
struct icmp *icmp;
struct timeva l *tvsend;
double rtt;
ip=(struct ip *)buf;
iphdrlen=ip->ip_hl<<2; /*求ip报头长度,即ip报头的长度标志乘4*/
icmp=(struct icmp *)(buf+iphdrlen); /*越过ip报头,指向ICMP报头*/
len-=iphdrlen; /*ICMP报头及ICMP数据报的总长度*/
if( len<8) /*小于ICMP报头长度则不合理*/
{ printf("ICMP packets\'s length is less than 8\n");
return -1;
}
/*确保所接收的是我所发的的ICMP的回应*/
if( (icmp->icmp_type==ICMP_ECHOREPLY) && (icmp->icmp_id==pid) )
{ tvsend=(struct timeva l *)icmp->icmp_data;
tv_sub(&tvrecv,tvsend); /*接收和发送的时间差*/
rtt=tvrecv.tv_sec*1000+tvrecv.tv_usec/1000; /*以毫秒为单位计算rtt*/
/*显示相关信息*/
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 a |