Subject: [Syslog] RE: Message format

From: "Rainer Gerhards" <[email-masked]>
Date: Wed, 23 Nov 2005 09:22:46 +0100

Hi Andrew,

(snipped for brevity)

> Mapping over UDP should be limited to a single message per packet.

I agree on that. If we need an ultra-compact UDP delivery, we could
later add it in a separate transport mapping.

> When mapping over plain TCP I believe we should limit the 
> total message size
> to 65507 bytes (to keep it compatible with UDP) and delimit 
> each message
> stream with an LF, or CRLF. Either delimiter would work for me.

I would prefer not to restart the size discussion at this point. I think
the current compromise (everyone must support 2K, anyone might support
as much as he likes) is sufficient for most, if not all, cases. I would
not like to see an application to become non-compliant just because it
needs to transmit 65508 bytes inside a message.

Rainer 

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---

From: "Andrew Ross" <[email-masked]>
Date: Wed, 23 Nov 2005 21:52:52 +1300

>later add it in a separate transport mapping.

Yes, good idea. I doubt anyone will ever want to do this, or at least go to
the effort of trying to get it drafted into an RFC ;-)

>needs to transmit 65508 bytes inside a message.

<SOAPBOX>
I realise this should have been brought up earlier in the draft process,
however, I would really like to see a limit on the message size so that it
is directly compatible with UDP. If we allow an opened ended message size,
people *will* use it for non syslog related things. I feel that any message
longer than will fit into a UDP packet should be broken into two or more
separate messages by the sender, even if sent over TCP. This allows me to
allocate a maximum known buffer size for incoming TCP messages. There is a
potential for huge messages filling the memory and memory buffer overflows
happening if the messages are not limited in size. "Syslog" is meant to be a
human readable system log message. Anything longer (including binary crash
dumps or other things people misuse syslog for) should be broken into
separate messages by the sender, or sent over a different protocol.
</SOAPBOX>

I think we should keep syslog simple and flexible, but not at the expense of
making it handle things it was never meant for. If a message needs to be
broken into many chunks, the SD-ID tags could be used to tie all the
messages together again by the parser. The syslog receiver or relay will
just handle them as separate messages and not even know they were split.
This makes things so much simpler.

Cheers

Andrew