Testing if a given IP is in a given network

ipinnet.py

def ip2int(ip):
	(f,s,t,l)=ip.split('.')
	return (int(f)*16777216)+(int(s)*65536)+(int(t)*256)+int(l)

def ipInNet(ip, network, masklength):
	mask = 0xFFFFFFFF << (32 - int(masklength))
	if (ip2int(ip) & mask) == (ip2int(network) & mask):
		return True
	else:
		return False

ip = "10.0.0.55"
networka = "10.0.0.0"
netmaska = 24
networkb = "10.0.0.0"
netmaskb = 16
networkc = "9.0.0.0"
netmaskc = 8
networkd = "10.10.0.0"
netmaskd = 8
networke = "10.10.0.0"
netmaske = 24

ipInNet(ip, networka, netmaska)  # Yields True
ipInNet(ip, networkb, netmaskb)  # Yields True
ipInNet(ip, networkc, netmaskc)  # Yields False
ipInNet(ip, networkd, netmaskd)  # Yields True
ipInNet(ip, networke, netmaske)  # Yields False