Ping source code

Ping source code-general Linux technology-Linux programming and kernel information. The following is a detailed description. /* PING. C
/*
/* Ping source code distribute by cpu | digger.
/* For unix family only. compil and link success in sco unix.
/* I think linux no problem too. u can try it.
/* Before read this code, you shoud know about the principle
/* TCP/IP, especially icmp protocol, u also shoshould also know some
/* About BSD socket API, and unix system signal programming.
/*
/* Cc-o ping. c-lsocket, then u will get executable file,
/* But must act as root when cc it, and then set euid attribute
/* For this ping, then u can execute it as common user.
/* Because only root can have authority to creat raw socket.
/*
/* I love socket, if so do u,
/* Call me, cpu = digger

# Include
# Include
# Include
# Include
# Include
# Include
# Include
# Include
# Include
# Include

# Define ICMP_ECHO 8/* icmp echo requir */
# Define ICMP_ECHOREPLY 0/* icmp echo reply */
# Define ICMP_HEADSIZE 8/* icmp packet header size */
# Define IP_HEADSIZE 20/* ip packet header size */

Typedef struct tagIpHead/* icmp packet header */
{
U_char ip_verlen;/* ip version and ip header lenth */
U_char ip_tos;/* ip type of service */
U_short ip_len;/* ip packet lenghth */
U_short ip_id;/* ip packet identification */
U_short ip_fragoff;/* ip packet fragment and offset */
U_char ip_ttl;/* ip packet time to live */
U_char ip_proto;/* ip packet protocol type */
U_short ip_chksum;/* ip packet header checksum */
U_long ip_src_addr;/* ip source ip adress */
U_long ip_dst_addr;/* ip destination ip adress */
} IPHEAD;

Typedef struct tagIcmpHead/* icmp header */
{
U_char icmp_type;/* icmp service type */
/* 8 echo require, 0 echo reply */
U_char icmp_code;/* icmp header code */
U_short icmp_chksum;/* icmp header chksum */
U_short icmp_id;/* icmp packet identification */
U_short icmp_seq;/* icmp packet sequent */
U_char icmp_data [1];/* icmp data, use as pointer */
} ICMPHEAD;

U_short ChkSum (u_short * pIcmpData, int iDataLen)
/* For check sum of icmp header */
{
U_short iSum;
U_short iOddByte;

ISum = 0;

While (iDataLen> 1) {/* xor the next unsigned int data */
ISum ^ = * pIcmpData ++;
IDataLen-= 2;
}

If (iDataLen = 1) {/* the rest odd byte */
IOddByte = 0;
* (U_char *) & iOddByte) = * (u_char *) pIcmpData;
ISum ^ = iOddByte;
}

ISum ^ = 0 xffff;/* xor 0 xffff = not it */
Return (iSum );
}

Long time_now ()/* return time passed */
/* Since 1970.1.1 00:00:00 ,*/
/* In 1/1000000 second */
{
Struct timeval now;
Long lPassed;
Gettimeofday (& now, 0 );
LPassed = now. TV _sec * 1000000 + now. TV _usec;
/* Now. TV _sec in second */
/* Now. TV _usec in 1/1000000 second */
Return lPassed;
}

Char * host;/* destination host */
Char * prog;/* program name */
Extern errno;/* system global parameter */
Long lSendTime;/* each time when send, change it */
U_short seq;/* the icmp packet seqence */
Int iTimeOut;/* time out parameter */
Int sock, sent, recvd, max, min, total;
/* Sent: icmp packet already sent */
/* Recvd: proper icmp packet already ed */
/* Max, min: max min round trip time */
/* Total: total round trip time */
/* Store to calculate average */
U_long lHostIp;/* host ip adress */
Struct sockaddr_in it;/* destination host information */

Int ping ();
Void stat ();

Main (int argc, char ** argv)
{
Struct hostent * h;
Char buf [200];
Char dst_host [32];
Int I, namelen;
IPHEAD * pIpHead;
ICMPHEAD * pIcmpHead;

If (argc <2) {/* ping the destination host */
/* Every timeout second */
/* Default timeout is 1 second */

Printf ("usage: % s [-timeout] host | IP \ n", argv [0]);
Exit (0 );
}
Prog = argv [0];
Host = argc = 2? Argv [1]: argv [2];
ITimeOut = argc = 2? 1: atoi (argv [1]);

/* Creat the raw socket for icmp */

If (sock = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP) <0 ){
Perror ("socket ");
Exit (2 );
}

/* Set destination host information */

Bzero (& it, sizeof (it ));
It. sin_family = AF_INET;

/* Check host format */

If (lHostIp = inet_addr (host ))! = INADDR_NONE ){
/* Is available ip adress */
It. sin_addr.s_addr = lHostIp;
Strcpy (dst_host, host );
} Else if (h = gethostbyname (host )){
/* Is available host name */
/* From hosts file of local host */
/* Or from DNS */
Bcopy (h-> h_addr, & it. sin_addr, h-> h_length );
Sprintf (dst_host, "% s (% s)", host,
Inet_ntoa (it. sin_addr ));
} Else {
/* Bad ip adress or host name */
/* Exit */
Fprintf (stderr, "bad IP or host \ n ");
Exit (3 );
}
Namelen = sizeof (it );

Printf ("\ nDigger pinging % s, send % d bytes \ n ",
Dst_host,
IP_HEADSIZE + ICMP_HEADSIZE + sizeof (long)
);

Seq = 0;/* first icmp_seq = 0 */
Sigset (SIGINT, stat);/* when press del or ctrl + c, call stat */
/* To statistic the result, and then exit */
Sigset (SIGALRM, ping);/* hook ping function to timer */
Alarm (iTimeOut);/* start timer, call ping every timeout */
/* Seconds */
Ping ();
For (;) {/* waiting for every echo back */
/* Icmp packet and check it */
Register size;
Register u_char ttl;
Register delta;
Register iIpHeadLen;

/* Block to received echo back datax */

Size = recvfrom (sock, buf, sizeof (buf), 0,
(Struct sockaddr *) & it, & namelen );
If (size =-1 & errno = EINTR ){
/* Receive error or system call */
/* Interrupted */
Continue;
}

/* Calculate the round trip time ,*/
/* Time when receive minus time when send */

Delta = (int) (time_now ()-lSendTime)/1000 );

/* Get echo back packet and check its ip header */

PIpHead = (IPHEAD *) buf;

/* Get the ip packet lenth */
/* If too small, not the icmp echoreply packet */
/* Give it up */

IIpHeadLen = (int) (pIpHead-> ip_verlen & 0x0f) <2 );
If (size <iIpHeadLen + ICMP_HEADSIZE ){
Continue;
}
Ttl = pIpHead-> ip_ttl;/* time to live param */

/* Get the icmp header information */
PIcmpHead = (ICMPHEAD *) (buf + iIpHeadLen );

/* Not icmp echo reply packet, give it up */
If (pIcmpHead-> icmp_type! = ICMP_ECHOREPLY ){
Continue;
}

/* Not proper icmp sequent number, give it up */
If (pIcmpHead-> icmp_id! = Seq | pIcmpHead-> icmp_seq! = Seq ){
Continue;
}

/* Print out result for each icmp */
/* Echo reply information */
Sprintf (buf, "icmp_seq = % u bytes = % d ttl = % d ",
PIcmpHead-> icmp_seq, size, ttl );
Fprintf (stderr, "reply from % s: % s time = % d ms \ n ",
Host, buf, delta );

/* Calculate some statistic information */
/* Max, min, average round trip time */
/* Received icmp echo reply packet numbers */
Max = MAX (delta, max );
Min = min? MIN (delta, min): delta;
Total + = delta;
++ Recvd;

/* For next icmp sequence */

++ Seq;
}
}

Ping ()
{
Char buf [200];
Int iPacketSize;

/* Make the icmp header information */

ICMPHEAD * pIcmpHead = (ICMPHEAD *) buf;
PIcmpHead-> icmp_type = ICMP_ECHO;
PIcmpHead-> icmp_code = 0;
PIcmpHead-> icmp_id = seq;
PIcmpHead-> icmp_seq = seq;
PIcmpHead-> icmp_chksum = 0;

/* Store time information as icmp packet content, 4 bytes */
/* U may store other information instead */

* (Long *) pIcmpHead-> icmp_data) = time_now ();

IPacketSize = ICMP_HEADSIZE + 4;/* icmp packet length */

/* Icmp header check sum */

PIcmpHead-> icmp_chksum = ChkSum (u_short *) pIcmpHead,
IPacketSize );

/* Remember the time when send for calculate round trip time */
LSendTime = time_now ();

/* Send the icmp packet to des host */
If (sendto (sock, buf, iPacketSize, 0, (struct sockaddr *) & it,
Sizeof (it) <0 ){
Perror ("send failed ");
Exit (6 );
}

/* Packet number been sent */
++ Sent;

/* Reset the timer hooker to me again */
Alarm (iTimeOut );
}

Void stat ()/* print the statistic information for this time's ping */
{
If (sent ){
Printf ("\ n ----- % s ping statistics summerized by Digger ----- \ n"
, Host );
Printf ("% d packets sent, % d packets received, %. 2f % lost \ n ",
Sent, recvd, (float) (sent-recvd)/(float) sent * 100 );
}
If (recvd ){
Printf ("round_trip min/avg/max: % d/% d ms \ n ",
Min, total/recvd, max );
}
Exit (0 );
}