Big-endian binary data to/from Python ints?

[William McBrine]

Here are a couple of functions that I feel stupid for having written. 
They work, and they're pretty straightforward; it's just that I feel like 
I must be missing an easier way to do this...

def net_to_int(numstring):
    """Convert a big-endian binary number, in the form of a string of
    arbitrary length, to a native int.
    """
    num = 0
    for i in numstring:
        num *= 256
        num += ord(i)
    return num

def int_to_net(num):
    """Convert a native int to a four-byte big-endian number, in the form
    of a string.
    """
    numstring = ''
    for i in xrange(4):
        numstring = chr(num % 256) + numstring
        num /= 256
    return numstring

The situation: I'm getting a four-byte packet from a socket that consists 
of a big-endian 32-bit integer. (It specifies the length of the data that 
follows.) I have to send the same thing in reply. send() and recv() work 
with strings... I'm familiar with ntohl() and htonl(), but those expect/ 
return integers.

-- 
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 -- pass it on