#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <setjmp.h>
#include <errno.h>
#include <sys/time.h>
#define PACKET_SIZE 4096
#define MAX_WAIT_TIME 5
#define MAX_NO_PACKETS 3
#define _DEBUG_ 1
char sendpacket[PACKET_SIZE];
char recvpacket[PACKET_SIZE];
int sockfd, datalen = 8;
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);
printf("catch signal\n");
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字节数据的低字节，这个2字节数据的高字节为0，继续累加*/
if (nleft == 1)
{
//*(unsigned char *)(&answer)=*(unsigned char *)w;
//answer = (*(unsigned char *)w) << 8;
//printf("answer = %x\n", answer);
sum += *(unsigned char *)w;
printf("sum = %x\n", sum);
}
sum = (sum>>16) + (sum&0xffff);
sum += (sum>>16);
answer =~ sum;
return answer;
}
/*设置ICMP报头*/
int pack(int pack_no)
{
int 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*/
#if _DEBUG_
//printf("sec = %ld, usec = %ld\n", tval->tv_sec, tval->tv_usec);
#endif
icmp->icmp_cksum = cal_chksum( (unsigned short *)icmp,packsize); /*校验算法*/
#if _DEBUG_
printf("cksum = 0x%x\n", icmp->icmp_cksum);
#endif
return packsize;
}
/*发送三个ICMP报文*/
void send_packet()
{
int packetsize;
{
nsend++;
packetsize = pack(nsend); /*设置ICMP报头*/
#if _DEBUG_
//printf("nsend = %d, packetsize = %d\n", nsend, packetsize);
#endif
if (sendto(sockfd, sendpacket, packetsize, 0,
(struct sockaddr *)&dest_addr, sizeof(dest_addr)) < 0)
{
perror("sendto error");
return;
}
//usleep(1000); /*每隔一秒发送一个ICMP报文*/
}
}
/*接收所有ICMP报文*/
void recv_packet()
{
int n, count = 0;
socklen_t fromlen;
extern int errno;
//fromlen = sizeof(from);
while ( count < 2)
{
count++;
fromlen = sizeof(from);
alarm(MAX_WAIT_TIME);
if ((n = recvfrom(sockfd, recvpacket, sizeof(recvpacket), 0,
(struct sockaddr *)&from, &fromlen)) < 0)
{
if (errno == EINTR)
{
printf("errno == EINTR\n");
continue;
}
perror("recvfrom error");
continue;
}
alarm(0);
printf("n = %d\n", n);
//gettimeofday(&tvrecv, NULL); /*记录接收时间*/
if (unpack(recvpacket, n) == -1) continue;
nreceived++;
break;
}
return;
}
/*剥去ICMP报头*/
int unpack(char *buf,int len)
{
int iphdrlen;
struct ip *ip;
struct icmp *icmp;
struct timeval *tvsend;
double rtt;
ip = (struct ip *)buf;
iphdrlen = ip->ip_hl<<2; /* ip_hl is the words of ip header*/
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*/
//printf("%d, icmp_id = %d\n", ICMP_ECHOREPLY, icmp->icmp_id);
if ((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid))
{
gettimeofday(&tvrecv, NULL);
#if _DEBUG_
//printf("sec = %ld, usec = %ld\n", tvrecv.tv_sec, tvrecv.tv_usec);
#endif
tvsend = (struct timeval *)icmp->icmp_data;
tv_sub(&tvrecv, tvsend); /*接收和发送的时间差*/
rtt = tvrecv.tv_sec*1000 + (double)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);
return 1;
}
else return -1;
}
int main(int argc,char *argv[])
{
struct hostent *host;
struct protoent *protocol;
unsigned long inaddr = 0l;
//int waittime = MAX_WAIT_TIME;
memset(sendpacket, 'a', sizeof(sendpacket));
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);
}
/*生成使用ICMP的原始套接字,这种套接字只有root才能生成*/
#if _DEBUG_
printf("the protocol number used is %d\n", protocol->p_proto);
#endif
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;
/*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*/
{
memcpy( (char *)&dest_addr.sin_addr.s_addr, (char *)&inaddr, sizeof(inaddr));
}
/*获取main的进程id,用于设置ICMP的标志符*/
pid = getpid();
printf("PING %s(%s): %d bytes data in ICMP packets.\n",argv[1],
inet_ntoa(dest_addr.sin_addr),datalen);
signal(SIGALRM, statistics);
while (nsend < MAX_NO_PACKETS)
{
send_packet(); /*发送所有ICMP报文*/
recv_packet(); /*接收所有ICMP报文*/
sleep(1);
}
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 -----------*/
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