Conversion from IP string to integer, and backward in Python

Question

i have a little problem with my script, where i need to convert ip in form \'xxx.xxx.xxx.xxx\' to integer representation and go back from this form.

def ipto         


        

Answer 1

Let me give a more understandable way:

ip to int

def str_ip2_int(s_ip='192.168.1.100'):
    lst = [int(item) for item in s_ip.split('.')]
    print lst   
    # [192, 168, 1, 100]

    int_ip = lst[3] | lst[2] << 8 | lst[1] << 16 | lst[0] << 24
    return int_ip   # 3232235876

The above:

lst = [int(item) for item in s_ip.split('.')]

equivalent to :

lst = map(int, s_ip.split('.'))

also:

int_ip = lst[3] | lst[2] << 8 | lst[1] << 16 | lst[0] << 24

equivalent to :

int_ip = lst[3] + (lst[2] << 8) + (lst[1] << 16) + (lst[0] << 24)

int_ip = lst[3] + lst[2] * pow(2, 8) + lst[1] * pow(2, 16) + lst[0] * pow(2, 24)

int to ip:

def int_ip2str(int_ip=3232235876):
    a0 = str(int_ip & 0xff)
    a1 = str((int_ip & 0xff00) >> 8) 
    a2 = str((int_ip & 0xff0000) >> 16)
    a3 = str((int_ip & 0xff000000) >> 24)

    return ".".join([a3, a2, a1, a0])

or:

def int_ip2str(int_ip=3232235876):
    lst = []
    for i in xrange(4):
        shift_n = 8 * i
        lst.insert(0, str((int_ip >> shift_n) & 0xff))

    return ".".join(lst)