ip6.IP6._protosw.update() is premature

Using Python 2.7 which randomizes hash key order, ip.__load_protos() may 
implicitly __import__() the ip6 module before some of the other protocols are 
populated into ip.IP._protosw.  If we do IP6._protosw.update(ip.IP._protosw) as 
is done currently, then IP6 would only get a subset of protocols that happen to 
be defined so far, and due to hash key randomization, this could very well be 
the empty set.

Moreover, ip6 could not import ip before class IP6 is defined.  The workaround 
here is to do this after class IP6, forcing the sharing of dictionary rather 
than making a copy.

import ip
IP6._protosw = ip.IP._protosw

Attaching a patch which I verified to work.

liulk

Original issue reported on code.google.com by liulk@google.com on 28 Nov 2012 at 5:43

Attachments:

ip6.py.diff

afghanistanyn / dpkt

ip6.IP6._protosw.update() is premature #99