Quick Python script I whipped up to review for a Computer Networking exam.

ip_addresses.py

BYTE = 8

def toBinaryString(num):
	bitstring = ""
	
	if num == 0:
		bitstring = '0'
	
	while num != 0:
		bitstring = str(num % 2) + bitstring
		num /= 2
	
	return bitstring

def pad(bitstring, packsof):
	limit = len(bitstring)
	
	if limit >= packsof:
		return bitstring
	else:
		return ('0' * (packsof - limit)) + bitstring

def iptobits(ipstring):
	ipbits = ""
	ipparts = ipstring.split(".")
	i = 0
	limit = len(ipparts)
	
	while i < limit:
		ipbits += pad(toBinaryString(int(ipparts[i])), BYTE)
		i += 1
	
	return ipbits

def bintodec(bitstring):
	decform = 0
	i = 0
	limit = len(bitstring)
	
	while i < limit:
		if bitstring[i] == '1':
			decform += 2 ** (limit - 1 - i)
		
		i += 1
	
	return decform

def bitstring_and(bstr1, bstr2):
	if bstr1 == '1' and bstr2 == '1':
		return '1'
	else:
		return '0'

def bitstring_or(bstr1, bstr2):
	if bstr1 == '1' or bstr2 == '1':
		return '1'
	else:
		return '0'

def toDottedDecimal(bitstring):
	i = 0
	byte_end = 8
	limit = len(bitstring)
	dotted_decimal = ""
	
	while byte_end <= limit:
		dotted_decimal += str(bintodec(bitstring[i:byte_end])) + '.'
		i = byte_end
		byte_end += 8
	
	return dotted_decimal[0:len(dotted_decimal) - 1]

def aggregate(broken_ip):
	i = 1
	limit = len(broken_ip)
	aggregate = broken_ip[0]
	
	while i < limit:
		aggregate += '.' + broken_ip[i]
		i += 1
	
	return aggregate

def read_ipmask(ipmaskstring):
	ipmask_dichotomy = ipmaskstring.split('/')
	ip = ipmask_dichotomy[0]
	ipbits = iptobits(ip)
	mask = int(ipmask_dichotomy[1])
	netmask = ('1' * mask) + ('0' * (32 - mask))
	net_address = ""
	i = 0
	limit = len(ipbits)
	
	while i < limit:
		net_address += bitstring_and(ipbits[i], netmask[i])
		i += 1
	
	net_address = toDottedDecimal(net_address)
	
	#flip the netmask now
	i = 0
	flipped_mask = ""
	
	while i < limit:
		if netmask[i] == '1':
			flipped_mask += '0'
		else:
			flipped_mask += '1'
		
		i += 1
	
	#get the broadcast address, bitstring_or the flipped
	#netmask with ipbits.
	i = 0
	broadcast = ""
	
	while i < limit:
		broadcast += bitstring_or(ipbits[i], flipped_mask[i])
		i += 1
	
	broadcast = toDottedDecimal(broadcast)
	
	print "IP:", ipmaskstring
	print "Netmask:", netmask, "=", toDottedDecimal(netmask)
	print "Net Address:", net_address
	print "Broadcast Address:", broadcast
	
	#Compute the Host address
	
	na_split = net_address.split('.')
	first_address = int(na_split[len(na_split) - 1]) + 1 #Handle overflow!
	na_split[len(na_split) - 1] = str(first_address)
	
	bc_split = broadcast.split('.')
	last_address = int(bc_split[len(bc_split) - 1]) - 1
	bc_split[len(bc_split) - 1] = str(last_address)
	
	print "Host Address:", aggregate(na_split), "to", aggregate(bc_split)

InPut = raw_input("Enter IP/Mask: ")

while InPut != "#":
	read_ipmask(InPut)
	InPut = raw_input("Enter IP/Mask: ")