Re: Darwin NKE question
Re: Darwin NKE question
- Subject: Re: Darwin NKE question
- From: Justin Walker <email@hidden>
- Date: Fri, 18 Apr 2003 17:20:21 -0700
On Friday, Apr 18, 2003, at 16:12 US/Pacific, Eric Long wrote:
Hi,
I'm wondering if anyone can confirm for me what the expectations are in
regard to the OS sbappend() function and network kernel extensions. I
had
thought that mbufs passing through here would always be in order, but
I'm
wondering if that is a trustworthy assumption.
Care to say what "in order" means to you?
For TCP, modulo bugs, you should be able to count on the mbufs
delivering data in the proper order (i.e., the order with which the
remote application sent it). For UDP, of course, there is no such
guarantee. Also, you should be aware that all that TCP guarantees is
order and correctness; there is no guarantee regarding packet content
vs. mbuf content (an mbuf may be part of the data in a received packet;
or it may be data from multiple packets).
UDP is, by its nature, unordered, with no guarantees (other than that
provided by the checksum, at the UDP layer).
What kind of socket are you camped on? Note that at the socket layer
(where sbappend() operates) you will have lost, or not yet seen, all
protocol identity and information).
Regards,
Justin
--
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics | If you're not confused,
| You're not paying attention
*--------------------------------------*-------------------------------*
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