Re: [Libevent-users] Adding ipv6 support.

[Simon Perreault <simon.perreault@xxxxxxxxxxx>]

On 2011-02-07 12:53, Dave Hart wrote:
> If you only care about IPv4 and IPv6 sockets, consider using a union
> of the useful types:
> 
> typedef struct union_saddr_tag {
>     struct sockaddr            sa;
>     struct sockaddr_in       sin;
>     struct sockaddr_in6     sin6;
> } union_saddr;
> 
> Then use union_saddr as your generic type, distinguishing variants
> using sa.sa_family.  When calling functions that take a sockaddr *,
> use &my_saddr.sa and no potentially-bug-hiding cast is required.

Bad idea. You're substituting an explicit cast with an implicit cast.

An implicit cast is no less "potentially-bug-hiding". An explicit cast
at least *looks* like a cast, so that you can be extra careful when you
see one. When casting, you *want* the code to look ugly, to force you to
think about what you're doing.

Furthermore, you're ignoring alignment issues.

The best current practice is to use sockaddr_storage. See e.g.
http://www.kame.net/newsletter/19980604/ for more info.

Simon
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