在Python中确定主机是域名还是IP

Question

Is there a function in Python that determines if a hostname is a domain name or an IP(v4) address?

Note, the domain name may look like: alex.foo.bar.com or even (I think this is valid): 1.2.3.com .

Answer 1

One of the visual differences between IP and domain address is when you delete dots in the IP address the result would be a number. So based on this difference we can check if the input string is an IP or a domain address. We remove dots in the input string and after that check if we can convert the result to an integer or we get an exception.

def is_ip(address):
    return address.replace('.', '').isnumeric()

Although in some IP-Representations like dotted hexadecimal (eg 0xC0.0x00.0x02.0xEB ) there can be both letters and numbers in the IP-Address. However the top-level-domain (.org, .com, ...) never includes numbers. Using the function below will work in even more cases than the function above.

def is_ip(address):
    return not address.split('.')[-1].isalpha()

Answer 2

I'd use IPy to test if the string is an IP address, and if it isn't - assume it's a domain name. Eg:

from IPy import IP
def isIP(str):
    try:
        IP(str)
    except ValueError:
        return False
    return True