Hi Keiichi,
> >
> > > One example might be that if sender wants to use global destination
> > > address to talk to an onlink node for which it knows a smaller scope
> > > address. In that situation, setting LARGESCOPE
> > > socket option and passing AI flag to getaddrinfo() is recommended.
> >
> > For which socket are you intending to set the LARGESCOPE socket
> > option? Could you show an example code fragment that uses this option
> > (e.g., containing calls to getaddrinfo(), socket(), and connect() or
> > sendto())?
>
> I had the same feeling with Tatsuya.
>
Thanks for providing the example below. It is similar to what I had in
mind. I agree that setting IPV6_PREFER_DST socket option may be redundant
in most implementations.
I can see your and Jinmei's view point.
> For the particular case, that you quated, maybe we don't need
> IPV6_PREFER_DST_ option. If were you, I would write the following code:
>
> hints.ai_family = PF_UNSPEC;
> hints.ai_socktype = SOCK_STREAM;
> hints.ai_flags = AI_PREFER_SRC_LARGESCOPE|AI_PREFER_DST_LARGESCOPE;
> getaddrinfo("www.foobar.com", "http", &hints, &res0);
> for every res in res0 {
> s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
> setsockopt(s, IPPROTO_IPV6, IPV6_PREFER_SRC_LARGESCOPE=on);
> connect(s, res->ai_addr, res->ai_addrlen);
> ...
> }
>
> I think specifying IPV6_PREFER_DST_XXX doesn't have any meaning,
> because the destination address has already been chosen in
> getaddrinfo().
>
Are you suggesting to drop all the IPV6_PREFER_DST_*SCOPE socket-option
flags ? I'll discuss this with my co-authors of this draft.
Does any implementor in this list have any objection on dropping
the above socket option?
Thanks again,
-Samita
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