www.pudn.com > myping.rar > myping.c
/*
this ping program will not be affected by any signals.
*/
#include
#include
#include
#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 2
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);
int recv_packet(void);
int unpack(char *buf,int len);
void tv_sub(struct timeval *out,struct timeval *in);
int nsleep(double sleep_time);
/*
void statistics(int signo)
{ printf("\n-------------PING statistics-------------------\n");
printf("%d packets transmitted, %d received , %%%d lost\n",
nsend,nreceived,(nsend-nreceived)/nsend*100);
if (nreceived>0){
printf("alive\n");
}else{
printf("not alive\n");
}
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 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); /*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()
{
//printf("begin send packet\n");
int packetsize;
//printf("send times:");
while( nsendip_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;
}
//printf("icmp->icmp_type=%d,icmp->icmp_id=%d\n",icmp->icmp_type,icmp->icmp_id);
/*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 timeval *)icmp->icmp_data;
tv_sub(&tvrecv,tvsend); /*接收和发送的时间差*/
/*以毫秒为单位计算rtt*/
rtt=tvrecv.tv_sec*1000+tvrecv.tv_usec/1000;
/*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);
return 0;
}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;
int result;
if(argc<2)
{ printf("usage:%s hostname/IP address\n",argv[0]);
exit(1);
}
if( (protocol=getprotobyname("icmp") )==NULL)
{ perror("getprotobyname");
exit(1);
}
/*生成使用ICMP的原始套接字,这种套接字只有root才能生成*/
if( (sockfd=socket(AF_INET,SOCK_RAW,protocol->p_proto) )<0)
{ perror("socket error");
exit(1);
}
/* 回收root权限,设置当前用户权限*/
setuid(getuid());
/*扩大套接字接收缓冲区到50K这样做主要为了减小接收缓冲区溢出的
的可能性,若无意中ping一个广播地址或多播地址,将会引来大量应答*/
setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size) );
bzero(&dest_addr,sizeof(dest_addr));
dest_addr.sin_family=AF_INET;
fcntl(sockfd,F_SETFL,O_NONBLOCK);
/*判断是主机名还是ip地址*/
if( inaddr=inet_addr(argv[1])==INADDR_NONE)
{
if((host=gethostbyname(argv[1]) )==NULL) /*是主机名*/
{ perror("gethostbyname error");
exit(1);
}
memcpy( (char *)&dest_addr.sin_addr,host->h_addr,host->h_length);
}
else /*是ip地址*/
//dest_addr.sin_addr.s_addr=inaddr;
//memcpy( (char *)&dest_addr,(char *)&inaddr,host->h_length);
inet_aton(argv[1],&dest_addr.sin_addr);
/*获取main的进程id,用于设置ICMP的标志符*/
pid=getpid();
//printf("%d:PING %s(%s): %d bytes data in ICMP packets.\n",pid,argv[1],inet_ntoa(dest_addr.sin_addr),datalen);
send_packet(); /*发送所有ICMP报文*/
if((result=recv_packet())==1){ /*接收所有ICMP报文*/
printf("alive\n");
}else{
printf("not alive\n");
}
close(sockfd);
//statistics(SIGALRM); /*进行统计*/
return 0;
}
/*两个timeval结构相减*/
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;
}
/*------------- The End -----------*/
int nsleep(double sleep_time)
{
//printf("nsleep begin\n");
struct timespec tv;
/* Construct the timespec from the number of whole seconds... */
tv.tv_sec = (time_t) sleep_time;
/* ... and the remainder in nanoseconds. */
tv.tv_nsec = (long) ((sleep_time - tv.tv_sec) * 1e+9);
int rval = nanosleep (&tv, &tv);
if (rval == 0){
/* Completed the entire sleep time; all done. */
//printf("nsleep end ok\n");
return 0;
}else{
/* Some other error; bail out. */
//printf("nsleep end fail\n");
return rval;
}
//printf("nsleep end ok\n");
return 0;
}