/*This is a sample routine of ping.It's implemented with winsock1.1
* under windows 2000 professional and has been not tested under other
* platform.Our target is to illustrator the principles,so many details
* may be ignored.(author email:zhangwu2003@163.com)
*/
#include<stdio.h>
#include<windows.h>
#include<process.h>
#define SEND_SIZE 32
#define PACKET_SIZE 4096
#define ICMP_ECHO 8
#define ICMP_ECHOREPLY 0
struct icmp
{
unsigned char icmp_type;
unsigned char icmp_code;
unsigned short icmp_cksum;
unsigned short icmp_id;
unsigned short icmp_seq;
unsigned long icmp_data;
};
struct ip
{
unsigned char ip_hl:4;
unsigned char ip_v:4;
unsigned char ip_tos;
unsigned short ip_len;
unsigned short ip_id;
unsigned short ip_off;
unsigned char ip_ttl;
unsigned char ip_p;
unsigned short ip_sum;
unsigned long ip_src;
unsigned long ip_dst;
};
unsigned char sendpacket[PACKET_SIZE];
unsigned char recvpacket[PACKET_SIZE];
struct sockaddr_in dest_addr;
struct sockaddr_in from_addr;
int sockfd;
int pid;
unsigned short cal_chksum(unsigned short *addr,int len);
int pack(int pack_no);
int unpack(unsigned char *buf,int len);
void send_packet(void);
void recv_packet(void);
void main(int argc,char *argv[])
{
struct hostent *host;
struct protoent *protocol;
WSADATA wsaData;
int timeout=1000;
int SEND_COUNT=4;
int i;
char *par_host;
par_host=argv[argc-1];
switch(argc)
{
case 2: break;
case 3: if(strcmp(argv[1],"-t")==0)
{
SEND_COUNT=10000;
break;
}
//fall through
default:
printf("usage: %s [-t] Host name or IP address\n",argv[0]);
exit(1);
}
if(WSAStartup(0x1010,&wsaData)!=0)
{
printf("wsastartup error\n");
exit(1);
}
if( (protocol=getprotobyname("icmp") )==NULL)
{
printf("getprotobyname error\n");
exit(1);
}
if( (sockfd=socket(AF_INET,SOCK_RAW,protocol->p_proto) )<0)
{
printf("socket error\n");
exit(1);
}
if(setsockopt(sockfd,SOL_SOCKET,SO_RCVTIMEO,(char*)&timeout,sizeof(timeout))<0)
fprintf(stderr,"failed to set recv timeout: %d\n",WSAGetLastError());
if(setsockopt(sockfd,SOL_SOCKET,SO_SNDTIMEO,(char*)&timeout,sizeof(timeout))<0)
fprintf(stderr,"failed to set send timeout: %d\n",WSAGetLastError());
memset(&dest_addr,0,sizeof(dest_addr));
dest_addr.sin_family=AF_INET;
if(host=gethostbyname(par_host) )
{
memcpy( (char *)&dest_addr.sin_addr,host->h_addr,host->h_length);
//resolve address to hostname
if(host=gethostbyaddr(host->h_addr,4,PF_INET))
par_host=host->h_name;
}
else if( dest_addr.sin_addr.s_addr=inet_addr(par_host)==INADDR_NONE)
{
printf("Unkown host %s\n",par_host);
exit(1);
}
pid=getpid();
printf("Pinging %s [%s]: with %d bytes of data:\n\n",par_host,inet_ntoa(dest_addr.sin_addr),SEND_SIZE);
for(i=0;i<SEND_COUNT;i++)
{
send_packet();
recv_packet();
Sleep(1000);
}
}
//this algorithm is referenced from other's
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;
}
//打包
int pack(int pack_no)
{
int packsize;
struct icmp *icmp;
packsize=8+SEND_SIZE;
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;
icmp->icmp_data=GetTickCount();
icmp->icmp_cksum=cal_chksum( (unsigned short *)icmp,packsize); /*校验算法*/
return packsize;
}
//解包
int unpack(unsigned char *buf,int len)
{
struct ip *ip;
struct icmp *icmp;
double rtt;
int iphdrlen;
ip=(struct ip *)buf;
iphdrlen=ip->ip_hl*4;
icmp=(struct icmp *)(buf+iphdrlen);
if( (icmp->icmp_type==ICMP_ECHOREPLY) && (icmp->icmp_id==pid) )
{
len=len-iphdrlen-8;
rtt=GetTickCount()-icmp->icmp_data;
printf("Reply from %s: bytes=%d time=%.0fms TTL=%d icmp_seq=%u\n",
inet_ntoa(from_addr.sin_addr),
len,
rtt,
ip->ip_ttl,
icmp->icmp_seq);
return 1;
}
return 0;
}
//发送
void send_packet()
{
int packetsize;
static int pack_no=0;
packetsize=pack(pack_no++);
if( sendto(sockfd,sendpacket,packetsize,0,(struct sockaddr *)&dest_addr,sizeof(dest_addr) )<0 )
printf("Destination host unreachable.\n");
// printf("send NO %d\n",pack_no-1);
}
//接收
void recv_packet()
{
int n,fromlen;
int success;
fromlen=sizeof(from_addr);
do
{
if( (n=recvfrom(sockfd,recvpacket,sizeof(recvpacket),0,(struct sockaddr *)&from_addr,&fromlen)) >=0)
success=unpack(recvpacket,n);
else if (WSAGetLastError() == WSAETIMEDOUT)
{
printf("Request timed out.\n");
return;
}
}while(!success);
}
