Example network protocol implementation

[M. Warner Losh]

In message: <eb7c8e2e0612100705o199393c4r353b7ff6fb058ed8 at mail.gmail.com>
            "Vishal Patil" <bsd.devil at gmail.com> writes:
: Would like to thank you all folks. These conversations are really good way
: of learning things...Also it is good to know different perspectives for
: solving the same problem....

Yes.  the ng_iscsi suggestion is also viable.  It may be a little less
work than going to the raw sockets.  Careful performance measurements
may be necessary, however, since there have been cases when the ng_foo
implementation wasn't fast enough and going to a lower level was
necessary.  There have also been many cases where ng_bar was perfectly
fast enough and there was no need to go to the lower leve.  At the
very least, the ng code will get you to layer your code well and
provide a faster means of development than going to the raw socket
layer.

Warner

: On 12/10/06, Julian Elischer <julian at elischer.org> wrote:
: >
: > Özkan KIRIK wrote:
: > > I think netgraph subsystem provides this infrastructure for implementing
: > > new protocols.
: > >
: > > according to netgraph (4) man page:
: > >
: > >    The aim of *netgraph* is to supplement rather than replace the
: > existing
: > >     kernel networking infrastructure.    It provides:
: > >
: > >     *·*     A flexible way of combining protocol and link level drivers.
: > >     *·*     A modular way to implement new protocols.
: > >     *·*     A common framework for kernel entities to inter-communicate.
: > >     *·*     A reasonably fast, kernel-based implementation.
: > >
: > > There are many examples and applications at this address:
: > > http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netgraph/
: >
: > also look it up in the daemon news archives at:
: > http://ezine.daemonnews.org/200003/netgraph.html
: >
: > a little out of date but the basic ideas are still right.
: >
: >
: > >
: > >
: > > you implementation may be "ng_iscsi" :)
: >
: > I thought of this but the trick is to do with the locking..
: > You would need to get a transfer of control from the
: > netgraph locking domain to the geom or scsi universe's locking domain.
: >
: > There are all the components needed if you consider using the ksocket
: > netgraph node to open a TCP socket within the kernel, and you could hook
: > that to a scsi device netgraph node almost directly if you wrote it,
: > but the hardest part will be to create a method of crossing that locking
: > divide.
: >
: > Still it's possibly worth looking at. Of course the method suggested by
: > Warner is also very valid and may be about the same amount of work.
: >
: >
: > >
: > > I hope this helps,
: > >
: > > Özkan KIRIK
: > > EnderUNIX SDT @ Turkey
: > > Software Developer
: > >
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