> > SCTP supports both SOCK_DGRAM, SOCK_STREAM as well as SOCK_SEQPACKET.
>
> SOCK_STREAM sounds odd since SCTP doesn't provide a byte stream service - it
> provides a service that has explicit message boundaries.
SCTP do provide three models (SOCK_xx).
draft-ietf-tsvwg-sctpsocket-07.txt talks about it more (it talks about
SOCK_SEQPACKET and SOCK_STREAM only, but the reference implementation
from [EMAIL PROTECTED] on KAME do provide SOCK_DGRAM too).
> > DCCP should be SOCK_DGRAM only, if i understand correctly.
>
> Also odd; you mean socket(AF_INET, SOCK_DGRAM, 0) might provide a DCCP
> socket on systems that support DCCP? Or IPPROTO_DCCP would need to
> be explicitly specified?
could be, but for backward compatibility's sake i guess 0 would give
you IPPROTO_UDP socket.
> > therefore, there's no 1-by-1 mapping from SOCK_xx to IPPROTO_xx.
>
> > to clarify, i agree there should be some way to support non-inet
> > protocols, however i'm not sure how service lookup works for non-inet
> > protocols. do people have any examples (such as appletalk or whatever)?
>
> I think that is what we need to figure out.
>
> Problem is that the socket() call takes both a type and a protocol argument
> and getnameinfo() has a single NI_DGRAM which implementations map to
> the single protocol argument in getservbyport().
>
> But this reminds me; doesn't SCTP use the same port number space as TCP?
basically the same space, but they do have separate entries on
/etc/services and http://www.iana.org/assignments/port-numbers.
for instance, http is only defined for http/tcp and http/udp at this
point of time. only a limited number of sctp services are defined on
IANA assignment page.
and since we have "foo/sctp" on /etc/services, we need to pass
"sctp" as 2nd arg to getservbyport(3).
> Will DCCP use the same port number space as either TCP or UDP?
IANA assignment page has no entry for dccp yet, so i'm not sure.
> The getnameinfo() man page seems to claim that NI_DGRAM is only needed
> because there are a few ports which are used for different protocols in UDP
> and TCP:
>
> A fifth flag bit, NI_DGRAM, specifies that the service is a
> datagram service, and causes getservbyport(3SOCKET) to be
> called with a second argument of "udp" instead of the
> default "tcp". This is required for the few ports (for
> example, 512-514) that have different services for UDP and
> TCP.
>
> If this isn't going to be an issue for SCTP or DCCP maybe we don't
> need to change anything.
it is going to be an issue. in fact, it already is.
itojun
--------------------------------------------------------------------
IETF IPv6 working group mailing list
[EMAIL PROTECTED]
Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------
