On Mar 26, 2007, at 1:30 AM, Thomas Dybdahl Ahle wrote:
Hi, I've writing a python application in which I'd like to have a
small
"ping label", to always tell the current ping time to the server.
It seems however that I have to be root to send those imcp
packages, but
I guess there must be a workaround since I can easily use the "ping"
command as ordinary user.
Do anybody know how to do this in python?
This won't solve your privileges issue, but this seems to get the
ping time to server:
import socket
import os
import sys
import struct
import time
import select
# 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.
#
# 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):
csum = 0
countTo = (len(str) / 2) * 2
count = 0
while count < countTo:
thisVal = ord(str[count+1]) * 256 + ord(str[count])
csum = csum + thisVal
csum = csum & 0xffffffffL # Necessary?
count = count + 2
if countTo < len(str):
csum = csum + ord(str[len(str) - 1])
csum = csum & 0xffffffffL # Necessary?
csum = (csum >16) + (csum & 0xffff)
csum = csum + (csum >16)
answer = ~csum
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 -1
timeReceived = time.time()
recPacket, addr = mySocket.recvfrom(1024)
icmpHeader = recPacket[20:28]
typ, 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 -1
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.
if sys.platform == 'darwin':
myChecksum = socket.htons(myChecksum) & 0xffff
else:
myChecksum = socket.htons(myChecksum)
header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0,
myChecksum, ID, 1)
packet = header + data
mySocket.sendto(packet, (destAddr, 1)) # Don't know about the 1
def doOne(destAddr, timeout=10):
# Returns either the delay (in seconds) or none on timeout.
icmp = socket.getprotobyname("icmp")
mySocket = socket.socket(socket.AF_INET,socket.SOCK_RAW,icmp)
myID = os.getpid() & 0xFFFF
sendOnePing(mySocket, destAddr, myID)
delay = receiveOnePing(mySocket, myID, timeout)
mySocket.close()
return delay
def ping(host, timeout=1):
dest = socket.gethostbyname(host)
delay = doOne(dest, timeout)
return delay
Hope this helps,
Michael
---
The Rules of Optimization are simple.
Rule 1: Don't do it.
Rule 2 (for experts only): Don't do it yet.
-- Michael A. Jackson , "Principles of
Program Design", 1975.
