Trouble converting hex to decimal?

[Jorgen Grahn]

On Sat, 05 Feb 2005 06:51:32 -0700, Earl Eiland <eee at nmt.edu> wrote:
> I'm trying to process the IP packet length field, as recorded by pcap
> (Ethereal) and recovered using pcapy.  When I slice out those bytes, I
> get a value that shows in '\x00' format, rather than '0x00'.  Neither
> int() nor eval() are working.  How do I handle this?

>From my unpublished protocol analyzing hack:

class Ip:
    "IPv4 header"
    def __init__(self, frame):
        (vi, tos, tlen,
         id, ffoff,
         ttl, proto, checksum,
         source,
         dest) = struct.unpack('! BBH HH BBH LL', frame[:20])
        self.len = 4 * (vi & 0xf)
        if proto==6:
            self.proto=Tcp
        elif proto==17:
            self.proto=Udp
        elif proto==1:
            self.proto=Icmp
        self.source = Address(source)
        self.dest = Address(dest)

That doesn't take IP options into account (or are they part of Ip.len? I
forget.), but it has the nifty feature that IP.proto tells the caller what
factory function (if any) she should feed the rest of the frame into.

/Jorgen

-- 
  // Jorgen Grahn <jgrahn@       Ph'nglui mglw'nafh Cthulhu
\X/                algonet.se>   R'lyeh wgah'nagl fhtagn!