home.public.bin/ip2dns

#! /usr/bin/python
#
# Read a list of domain names on stdin, look up the A records, print IPs on stdout
#
# Usgae:
#
#   echo google.com | dns2ip [-a]
#
# or
#
#   echo 8.8.8.8 | ip2dns
#
#
# The funcion (forward or reverse lookup) keys off the program name,
# so install by doing:
#
#    $ ln dns2ip ip2dns
#

import socket
#import fileinput
import dns.resolver
import sys
import getopt

def usage():
	sys.stderr.write("Usage: echo www.google.com | dnns2ip [options]\n")
	sys.stderr.write("   or\n")
	sys.stderr.write("       dns2ip [options]files-contianing-dns-names [files..]\n")
	sys.stderr.write("\n")					 
	sys.stderr.write("   options\n")
	sys.stderr.write("\n")					 	
	sys.stderr.write("     --names|-n	print name as well as resolved IPs\n")
	sys.stderr.write("     --all|-a	print IPs for all A records\n")	
	sys.exit(1)

# defaults
printName= False
printAll = False
verbose=False
inputName=""
progName=sys.argv[0]

options, remainder = getopt.getopt(sys.argv[1:], 'ahnvi:',
                                   ["all",
                                    'help',
									'input='
                                    'names',                                    
                                    "verbose",
								   ]
                                   )
for opt, arg in options:

    if opt in ('-h', '--help'):
        usage()
        sys.exit(2)
    elif opt in ('-i', '--input'):
        inputName = arg
    elif opt in ('-a', '--all'):
        printAll= True
    elif opt in ('-n', '--names'):
        printName= True
    elif opt in ('-v', '--verbose'):
        verbose=True
    else:
        usage()
        sys.exit(2)

if verbose:
	print "printName", printName
	print "printAll", printAll
	print "verbose", verbose
	print "inputName", inputName
	print "remainder", remainder

myResolver = dns.resolver.Resolver() #create a new instance named 'myResolver'

import fileinput

for name in fileinput.input(remainder):

	if verbose:
		print "name", name
	name = name.strip()

	atLeastOne = False
	
	try:
		myAnswers = []

		if "dns2ip" in progName:
			myAnswers = myResolver.query(name, "A") #Lookup the 'A' record(s) for google.com
		elif "ip2dns" in progName:
			addr=dns.reversename.from_address(name)
			reverse = str(dns.resolver.query(addr,"PTR")[0])
			myAnswers.append(reverse)
		else:
			usage()
			sys.exit(2)

		for rdata in myAnswers: #for each response
				
			sys.stdout.write("%s" % (rdata))

			if printName:
				sys.stdout.write(" %s\n" % (name))
			else:
				sys.stdout.write("\n")				

			atLeastOne = True

			if not printAll:
				last
	except:
		pass