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#!/usr/bin/env python
# Derived from ping.c distributed in Linux's netkit. That code is
# copyright (c) 1989 by The Regents of the University of California.
# That code is in turn derived from code written by Mike Muuss of the
# US Army Ballistic Research Laboratory in December, 1983 and
# placed in the public domain. They have my thanks.
# Bugs are naturally mine. I'd be glad to hear about them. There are
# certainly word-size dependenceies here.
# Copyright (c) Matthew Dixon Cowles, <http://www.visi.com/~mdc/>.
# Distributable under the terms of the GNU General Public License
# version 2. Provided with no warranties of any sort.
# Note that ICMP messages can only be sent from processes running
# as root.
# Revision history:
#
# November 22, 1997
# Initial hack. Doesn't do much, but rather than try to guess
# what features I (or others) will want in the future, I've only
# put in what I need now.
#
# December 16, 1997
# For some reason, the checksum bytes are in the wrong order when
# this is run under Solaris 2.X for SPARC but it works right under
# Linux x86. Since I don't know just what's wrong, I'll swap the
# bytes always and then do an htons().
#
# December 4, 2000
# Changed the struct.pack() calls to pack the checksum and ID as
# unsigned. My thanks to Jerome Poincheval for the fix.
#
import os
from socket import *
import struct
import select
import time
import sys
# From /usr/include/linux/icmp.h; your milage may vary.
ICMP_ECHO_REQUEST=8 # Seems to be the same on Solaris.
# I'm not too confident that this is right but testing seems
# to suggest that it gives the same answers as in_cksum in ping.c
def checksum(str):
sum=0
countTo=(len(str)/2)*2
count=0
while count<countTo:
thisVal=ord(str[count+1])*256+ord(str[count])
sum=sum+thisVal
sum=sum & 0xffffffff # Necessary?
count=count+2
if countTo<len(str):
sum=sum+ord(str[len(str)-1])
sum=sum & 0xffffffff # Necessary?
sum=(sum >> 16) + (sum & 0xffff)
sum=sum+(sum >> 16)
answer=~sum
answer=answer & 0xffff
# Swap bytes. Bugger me if I know why.
answer=answer >> 8 | (answer << 8 & 0xff00)
return answer
def receiveOnePing(mySocket,ID,timeout):
timeLeft=timeout
while 1:
startedSelect=time.time()
whatReady=select.select([mySocket],[],[],timeLeft)
howLongInSelect=(time.time()-startedSelect)
if whatReady[0]==[]: # Timeout
return None
timeReceived=time.time()
recPacket,addr=mySocket.recvfrom(1024)
icmpHeader=recPacket[20:28]
type,code,checksum,packetID,sequence=struct.unpack("bbHHh",icmpHeader)
if packetID==ID:
bytesInDouble=struct.calcsize("d")
timeSent=struct.unpack("d",recPacket[28:28+bytesInDouble])[0]
return timeReceived-timeSent
timeLeft=timeLeft-howLongInSelect
if timeLeft<=0:
return None
def sendOnePing(mySocket,destAddr,ID):
# Header is type (8), code (8), checksum (16), id (16), sequence (16)
myChecksum=0
# Make a dummy heder with a 0 checksum.
header=struct.pack("bbHHh",ICMP_ECHO_REQUEST,0,myChecksum,ID,1)
bytesInDouble=struct.calcsize("d")
data=(192-bytesInDouble) * "Q"
data=struct.pack("d",time.time())+data
# Calculate the checksum on the data and the dummy header.
myChecksum=checksum(header+data)
# Now that we have the right checksum, we put that in. It's just easier
# to make up a new header than to stuff it into the dummy.
header=struct.pack("bbHHh",ICMP_ECHO_REQUEST,0,htons(myChecksum),ID,1)
packet=header+data
mySocket.sendto(packet,(destAddr,1)) # Don't know about the 1
return None
def doOne(destAddr,timeout=10):
# Returns either the delay (in seconds) or none on timeout.
icmp=getprotobyname("icmp")
mySocket=socket(AF_INET,SOCK_RAW,icmp)
myID=os.getpid() & 0xFFFF
sendOnePing(mySocket,destAddr,myID)
delay=receiveOnePing(mySocket,myID,timeout)
mySocket.close()
return delay
def main():
if len(sys.argv)<2:
print "Usage: %s hostname" % os.path.basename(sys.argv[0])
sys.exit(1)
dest=gethostbyname(sys.argv[1])
delay=doOne(dest)
print delay
return None
if __name__=='__main__':
main()
sys.exit(0)