[quagga-dev 707] Re: q about prefix_same
gilad.arnold at terayon.com
Tue Jan 13 14:52:23 GMT 2004
sowmini.varadhan at Sun.COM wrote:
> Good question... is there a reason why prefix_same can't just do
> a single memcmp() instead of painfully first comparing family and
> len? Is there any padding in that structure?
Of course it can't, because (a) you want to be padding independant, and
this isn't a sequential type of data structure; (b) in this case, it's
obvious that the union member (prefix.u...) imposes trailing pad-bytes,
since sizeof(struct in_addr) < sizeof(struct in6_addr). Assuming some
non-virgin IPv6 prefix is assigned an IPv4 address/mask, you can't
guarantee the excess bytes are of any particular value, can you?
(PS: what's wrong with particle comparison anyway?)
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