manipulating hex values
gagsl-py2 at yahoo.com.ar
Tue Apr 1 20:04:55 CEST 2008
En Tue, 01 Apr 2008 14:11:31 -0300, Stephen Cattaneo
<stephen.cattaneo at u4eatech.com> escribió:
> I am relatively new to socket programming. I am attempting to use raw
> sockets to spoof my IP address.
Don't bother to try...
> From what I can tell I will have to
> build from the Ethernet layer on up. This is fine, but I am having
> some trouble with manipulating my hex values.
> Seems to me that there are two ways to store hex values:
> 1. as literal hex - 0x55aa
> 2. as a string - "\x55aa"
The later is exactly the same string as "Uaa":
py> print "\x55aa"
> If I want to convert hex to decimal I can use:
> int("\x55aa", 16) # note that plain 0x55aa, instead of "\x55aa", will
> raise an exception
Have you tried it?
py> int("\x55aa", 16)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 16: 'Uaa'
py> int("0x55aa", 16)
> The Question:
> If I want to do any kind of calculation I have found its best to just
> convert my values to decimal, do the math, then convert back to hex. In
> my bellow code I get
"decimal" and "hex" are just ways to represent/display integers. You
convert from the representation used on the source, to integer, do some
math, and convert again to another representation for display/store the
> ValueError: invalid literal for int()"""
> when attempting to run. I do not understand why this exception is
> being raised? It is a for loop iterating over a list of hex strings.
> Sorry for the long-ish question. Any help or comments would be
Use the struct package.
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