linux下ping C語言實現

1 #include 2 #include 3 #include 4 #include 5 #include 6 #include 7 #include in.h>

8 #include 9 #include 10 #include 11 #include 12 #include 13
#define packet_size     4096
14#define max_wait_time   5
15#define max_no_packets  3
16char
sendpacket[packet_size];
17char
recvpacket[packet_size];
18int sockfd,datalen=56;19
int nsend=0,nreceived=0;20
struct
sockaddr_in dest_addr;
21pid_t pid;
22struct sockaddr_in from;23
struct
timeval tvrecv;
24void statistics(int
signo);
25 unsigned short cal_chksum(unsigned short *addr,int
len);
26int pack(int
pack_no);
27void send_packet(void
);28
void recv_packet(void
);29
int unpack(char *buf,int
len);
30void tv_sub(struct timeval *out,struct timeval *in
);31
void statistics(int
signo)
32 38
/*校驗和演算法
*/39 unsigned short cal_chksum(unsigned short *addr,int
len)
40 50
/*若icmp報頭為奇數個位元組，會剩下最後一位元組。把最後乙個位元組視為乙個2位元組資料的高位元組，這個2位元組資料的低位元組為0，繼續累加
*/51
if( nleft==1
)52         
55         sum=(sum>>16)+(sum&0xffff
);56         sum+=(sum>>16
);57         answer=~sum;
58return
answer;59}
60/*
設定icmp報頭
*/61
int pack(int
pack_no)
62 77
/*傳送三個icmp報文
*/78
void
send_packet()
79 88                 sleep(1); /*
每隔一秒傳送乙個icmp報文
*/89}90
}91/*接收所有icmp報文
*/92
void
recv_packet()
93 105                 gettimeofday(&tvrecv,null);  /*
記錄接收時間
*/106
if(unpack(recvpacket,n)==-1)continue
;107                 nreceived++;
108}
109}
110/*
剝去icmp報頭
*/111
int unpack(char *buf,int
len)
112 
125/*
確保所接收的是我所發的的icmp的回應
*/126
if( (icmp->icmp_type==icmp_echoreply) && (icmp->icmp_id==pid) )
127         
138else
return -1
;139
}140 main(int argc,char *argv)
141 
150if( (protocol=getprotobyname("
icmp
") )==null)
151         
154/*
生成使用icmp的原始套接字,這種套接字只有root才能生成
*/155
if( (sockfd=socket(af_inet,sock_raw,protocol->p_proto) )<0
)156         
159/*
**root許可權,設定當前使用者許可權
*/160
setuid(getuid());
161/*
擴大套接字接收緩衝區到50k這樣做主要為了減小接收緩衝區溢位的
162的可能性,若無意中ping乙個廣播位址或多播位址,將會引來大量應答
*/163         setsockopt(sockfd,sol_socket,so_rcvbuf,&size,sizeof
(size) );
164         bzero(&dest_addr,sizeof
(dest_addr));
165         dest_addr.sin_family=af_inet;
166/*
判斷是主機名還是ip位址
*/167
if( inaddr=inet_addr(argv[1])==inaddr_none)
168         
172                 memcpy( (char *)&dest_addr.sin_addr,host->h_addr,host->h_length);
173}
174else
/*是ip位址
*/175                 memcpy( (char *)&dest_addr,(char *)&inaddr,host->h_length);
176/*
獲取main的程序id,用於設定icmp的標誌符
*/177         pid=getpid();
178         printf("
ping %s(%s): %d bytes data in icmp packets.\n
",argv[1
],179
inet_ntoa(dest_addr.sin_addr),datalen);
180         send_packet();  /*
傳送所有icmp報文
*/181         recv_packet();  /*
接收所有icmp報文
*/182         statistics(sigalrm); /*
進行統計
*/183
return0;
184}
185/*
兩個timeval結構相減
*/186
void tv_sub(struct timeval *out,struct timeval *in
)187 
191out->tv_sec-=in->tv_sec;
192}
193/*
------------- the end -----------
*/

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