signed 32-bit int to ipv4

signed_to_ipv4.py

def int_to_ip(signed_int):
    """ convert a 32-bit signed integer to an IP address"""
    # do preventative type checking because I didn't want to check inputs
    try:
        if type(signed_int) == str or type(signed_int) == int:
            signed_int = long(signed_int)
    except ValueError:
        return "err_ip"

    # CUCM occasionally creates CDRs with an IP of '0'. Bug or feature? Beats me.
    if signed_int == 0:
        return "err_ip"
    
    # hex conversion for 32-bit signed int; 
    # the slice at the end removes the '0x' and 'L' in the result
    h = hex(signed_int & 0xffffffff)[2:-1] 

    if len(h) == 7: #pad initial zero if required
        h = '0' + h

    hex_ip = [h[6:8],h[4:6],h[2:4],h[:2]] # reverse the octets

    #put them back together in IPv4 format
    ip = '.'.join([str(int(n,16)) for n in hex_ip]) 

    return ip