#!/s/bin/python -- # -*- python -*-
# $Id: ipcat,v 1.6 2002-01-16 12:36:20-06 annis Exp $
# $Source: /u/annis/scripts/RCS/ipcat,v $
#
# Copyright (c) 1998 - 2002 William S. Annis.  All rights reserved.
# This is free software; you can redistribute it and/or modify it
# under the same terms as Perl (the Artistic Licence).  Developed at
# the Department of Biostatistics and Medical Informatics, University
# of Wisconsin, Madison.


"""Cat stdout through a filter looking up IP addresses.
"""

import socket, sys, re, fileinput, string
from signal import signal, alarm, SIGALRM

# Register our timeout signal handler.
class Timeout(Exception): pass

def throw_timeout(sig, frame):
    raise Timeout(sig)

signal(SIGALRM, throw_timeout)

# Dictionary to cache addresses in.
ips = {}

# Return the resolved address if it exists, otherwise, just give back
# the IP version.
def lookup(addr):
    # If this address has been cached, use it; otherwise lookup into cache.
    if not ips.has_key(addr):
        # Assign the default first, which is just the IP.  That is,
        # if this lookup fails, assume it will fail for the rest of
        # the run of the script.
        ips[addr] = addr

        try:
            # Don't wait too long for an answer.
            alarm(5)
            (ips[addr], more, ip) = socket.gethostbyaddr(addr)
            alarm(0)
        except socket.error:
            # Lookup failed.  Reset alarm.
            alarm(0)
        except Timeout:
            # Lookup took too long.  Move on.
            pass
            
    return ips[addr]


# Use this precompiled regular expression to match IP addresses.
ipregexp = re.compile(r"(?:.*?(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}))", re.DOTALL)


def filter(line):
    """Filter a line's IP addresses into named addresses."""
    splits = ipregexp.split(line)

    # This is very tricky: keep track of everything we split at.
    for splitpat in splits[:-1]:
        ip = string.strip(splitpat)
        newaddr = lookup(ip)
        if newaddr != ip:
            line = re.sub(re.escape(ip), newaddr, line)
        
    return line

for line in fileinput.input():
    print filter(line),


# EOF