Re: [Tsvwg] SCTP stream EOF

[Randy Stewart <[e-mail]>]

On Sep 17, 2008, at 10:54 AM, Florian Niederbacher wrote:

> Randy Stewart schrieb:
>> Florian:
>>
>> What do you mean by an EOF?
> Same as EOF for files. That blocking recv and recvmsg can be stopped.
>>
>> For messages there is a SCTP_EOR to tell you a "message" as ended.
> Yes, but only for message you pick up from recv- buffer if I  
> interpret it right from socket_api-spec.
> E.g. transfer Hello in to messages hel - lo. After 'lo' I get an EOF.
> SCTP_EOR does only indicate that the message can be read in full in  
> one read/recv, or not? Because i get always SCTP_EOR in my app, only  
> if the messagesize is bigger then the buffer for recv\recv_msg.

If I have a recv buffer of 2 bytes and you send me "hello\n"
I would get
read (he - no eor)
read (ll - no eor)
read (o\n - EOR)

It depends on your read size...



>
>>
>>
>> If you were using stream reset, and the peer decides to "reset" a  
>> stream
>> and then use the stream for some other purpose (this is what I  
>> think you
>> are stating).... then the user would get a STREAM_RESET event for  
>> that
>> stream.
>>
>> I don't see the difference (other than name) in stream-x has been  
>> reset
>> vs stream X receives a EOF. Note that an app MAY choose to use a  
>> RESET
>> as a EOF.. but it can also mean something different to an app.. I  
>> am done
>> sending this type of message, I will now send other types of  
>> messages.
>> Which is different than an EOF....
> Yes I agree. I didn't know that STREAM_RESET is handled as event.  
> This would definitely solve my case. But is this already implemented  
> in LKSCTP?
>


We have it in FreeBSD but we as yet do not support adding more  
streams.. another
thing I need to add :)

I don't know about LKSCTP at the last interop they did not support it

R

>>
>> Note also that the socket-api section is still missing (if I  
>> remember right) from
>> the stream-reconfig draft... I do need to add this. But I really  
>> think
>> the Stream-Reset serves the purpose you are looking for.
>>
>> R
>> On Sep 17, 2008, at 9:49 AM, Florian Niederbacher wrote:
>>
>>> Hi,
>>> I would ask what are you thinking about a definition for an EOF on  
>>> streams in SCTP. My problem is that I would need a signaling  
>>> method to report an EOF without closing the whole SCTP  
>>> association. If I am right, socket connections get only an EOF if  
>>> the connection will be closed (no sending of EOF on socktes in  
>>> another way is possible). In draft-stewart-tsvwg-sctpstrrst-00 the  
>>> possibility the reset of streams is discussed. This would also be  
>>> a solution if you can check the numbering sequence in User Space.
>>> A proposal would be to generate an SCTP_EVENT e.g. SCTP_STREAM_EOF  
>>> to signal EOF on streams. In this way you can stop receiving and  
>>> also reuse the stream or at least continue in multi-streamed  
>>> network applications, if you use different threads or processes  
>>> for the receiving procedure on streams. Maybe an other possibility  
>>> exists to signal an EOF on SCTP streams, but at the moment I can't  
>>> find any solution to deal with this problem. What are your  
>>> proposals and comments?
>>>
>>> Best regards
>>> Florian Niederbacher
>>
>> -----
>> Randall Stewart
>> [e-mail]
>>
>>
>>
>>
>>
>
> - Regards Florian
>

-----
Randall Stewart
[e-mail]