Re: [tsvwg] [Technical Errata Reported] RFC6458 (6081)

[Michael Tuexen <[e-mail]>]

> On 9. Apr 2020, at 06:46, RFC Errata System <[e-mail]> wrote:
> 
> The following errata report has been submitted for RFC6458,
> "Sockets API Extensions for the Stream Control Transmission Protocol (SCTP)".
> 
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid6081
> 
> --------------------------------------
> Type: Technical
> Reported by: wanglihe <[e-mail]>
> 
> Section: GLOBAL
> 
> Original Text
> -------------
> 8.1.26    must indicate that they are
>   finished sending a particular record by including the SCTP_EOR flag.
> 
> but I can not find where to use SCTP_EOR flag.
> 
> because
> 
> 5.1  The msg_flags are not used when sending a message with sendmsg().
> 
> 3.1.4  flags:  No new flags are defined for SCTP at this level.  See
>      Section 5 for SCTP-specific flags used in the msghdr structure.
> 
> 4.1.8 same with 3.1.4
> 
> 9.10, 9.12    flags:  The same flags as used by the sendmsg() call flags (e.g.,
>      MSG_DONTROUTE).
> 
> 9.7   flags:  The same as sinfo_flags (see Section 5.3.2).
> 
> 5.3.2 sinfo_flags not mention about it  
> 
> Corrected Text
> --------------
> maybe msg_flags should be used.
I agree, that text describing where to use the SCTP_EOR flag is missing.

It can be used in the snd_flags field of the sctp_sndinfo structure.
It can also be used in the sinfo_flags field of the sctp_sndrcvinfo structure,
which is deprecated.
> 
> Notes
> -----
> Another problem is that, I think it should be discuss about debfine a flag like SCTP_BOR for beginning(init chunk) of a Record, because a stream of this socket(assoc) can still be used after send a SCTP_EOR.
I don't think this is needed, since if you know when a message ends, the next userdata on the same
stream with the same ordering property is the beginning.
> 
> And between  a init chunk and  a STCP_EOR,  if I change SCTP_EXPLICIT_EOR status, what the socket will send the message?
What happens if you are have not completed to provide a complete message and you turn off SCTP_EXPLICIT_EOR
is not specified. An implementation could fail the disabling of SCTP_EXPLICIT_EOR, but I don't think the
BSD stack does this. I guess (not tested) it will terminate the current message with the next send call.

Best regards
Michael
> 
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> 
> --------------------------------------
> RFC6458 (draft-ietf-tsvwg-sctpsocket-32)
> --------------------------------------
> Title               : Sockets API Extensions for the Stream Control Transmission Protocol (SCTP)
> Publication Date    : December 2011
> Author(s)           : R. Stewart, M. Tuexen, K. Poon, P. Lei, V. Yasevich
> Category            : INFORMATIONAL
> Source              : Transport Area Working Group
> Area                : Transport
> Stream              : IETF
> Verifying Party     : IESG
>