Re: Example network protocol implementation
On Sun, 10 Dec 2006, M. Warner Losh wrote: In message: [EMAIL PROTECTED] Vishal Patil [EMAIL PROTECTED] 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. As someone who doesn't consume Netgraph a lot, can you tell me what benefit using Netgraph for something like iSCSI might have when compared with the kernel socket API used to implement user sockets, NFS, SMB, etc? Are there parsing/decapsulation parts of the protocol that lend themselves well to netgraphs more modular approach vs. the more traditional approach of layering RPC wrapping over the socket layer? BTW, one of the things on my todo list is a socket(9) man page, which is well overdue. I've been postponing writing it while finishing up the kernel socket API cleanup in -CURRENT. Robert N M Watson Computer Laboratory University of Cambridge ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Example network protocol implementation
On Sat, 9 Dec 2006, Vishal Patil wrote: Could someone point me to an example that shows a SIMPLE network protocol implemented over TCP/IP inside the FreeBSD kernel. I think I could look at the NFS client driver but is there an example simpler than that. Also is there a guide explaining how to go about developing TCP/IP based network protocols for FreeBSD. Thanks Here are some consumers of sockets in the kernel: - NFS client, which creates and connects both UDP and TCP sockets, uses them for I/O, etc. - NFS server, which uses UDP and TCP sockets for I/O. Unlike the NFS client, it doesn't open the sockets in kernel, rather, it relies on a user process (nfsd) passing validated sockets into the kernel. - System V streams (dev/streams), which uses socket pairs to implement streams. Does creation and I/O. - fifofs, which implements POSIX fifos using a pair of UNIX domain sockets. Again, does creation and I/O. - portalfs, which implements the portal file system using sockets. - ng_ksocket, which provides a netgraph interface to sockets in the kernel. - netncp, which provides an NCP RPC interface over SPX/IPX for nwfs. - netsmb, which provides an SMB RPC interface over TCP/IP for smbfs. - rpclnt, which is used by the nfs4client, and is functionally similar to the NFS client RPC code for NFS2/NFS3 in nfsclient. - bootp_subr.c and krpc_subr.c, which are used by the NFS root code to set up NFS access during a diskless boot: they perform the bootp exchange to retrieve an IP address, and then the necessary RPC mount protocol to query a root file handle to set up the NFS client for the file system root. All of these examples have upsides and downsides, and vary in maturity. I'd probably start by looking at the NFS client and fifofs. One of the biggest questions you'll need to answer is what your event model is and how it will relate to any worker threads you may have. Many of the in-kernel socket consumers use socket upcalls to get direct notifications of socket events from within the network stack, allowing for fast socket draining and TCP acking. On the other hand, in the netisr/ithread context, you can't perform blocking memory allocation and disk I/O, so if that will be involved, you'll need worker threads in the style of the NFS server. Robert N M Watson Computer Laboratory University of Cambridge ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Example network protocol implementation
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 M. Warner Losh wrote: In message: [EMAIL PROTECTED] Vishal Patil [EMAIL PROTECTED] 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 [EMAIL PROTECTED] 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/23/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 : May be better to start from scratch though, studying other protocols, given the fact that networking technology is going to be increasing in leaps and bounds it seems in the next couple years (1Gbit - 10Gbit - 100Gbit). Just a thought, but it seems like an ad-hoc solution may be better in the long run.. - -Garrett -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFfP/c6CkrZkzMC68RAsUWAJ0YIstzev855y9t7tmtArvlSoQO4wCfblfa SmiAvkWrVJKvIxGb3skdwOg= =Bxm3 -END PGP SIGNATURE- ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Example network protocol implementation
Could someone point me to an example that shows a SIMPLE network protocol implemented over TCP/IP inside the FreeBSD kernel. I think I could look at the NFS client driver but is there an example simpler than that. Also is there a guide explaining how to go about developing TCP/IP based network protocols for FreeBSD. Thanks - Vishal ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Example network protocol implementation
Vishal Patil [EMAIL PROTECTED] wrote: Could someone point me to an example that shows a SIMPLE network protocol implemented over TCP/IP inside the FreeBSD kernel. I think I could look at the NFS client driver but is there an example simpler than that. NFS normally runs over UDP, not TCP. Telnet is one of the simpler TCP-based applications, but it is not done in the kernel (nor are most network apps). Is there some particular reason why you need an example that is implemented inside the kernel, vs in userland? ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Example network protocol implementation
On Saturday 09 December 2006 17:18, Vishal Patil wrote: Could someone point me to an example that shows a SIMPLE network protocol implemented over TCP/IP inside the FreeBSD kernel. I think I could look at the NFS client driver but is there an example simpler than that. Also is there a guide explaining how to go about developing TCP/IP based network protocols for FreeBSD. Try looking at telnet(1) and telnetd(8) source code, also fetch(1) should works too... Thanks - Vishal ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED] Best regards, -- . 0 . | Daniel Molina Wegener . . 0 | dmw at unete dot cl 0 0 0 | FreeBSD User ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Example network protocol implementation
For implementing iSCSI protocol as a kernel driver. On 12/9/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Vishal Patil [EMAIL PROTECTED] wrote: Could someone point me to an example that shows a SIMPLE network protocol implemented over TCP/IP inside the FreeBSD kernel. I think I could look at the NFS client driver but is there an example simpler than that. NFS normally runs over UDP, not TCP. Telnet is one of the simpler TCP-based applications, but it is not done in the kernel (nor are most network apps). Is there some particular reason why you need an example that is implemented inside the kernel, vs in userland? ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Example network protocol implementation
In message: [EMAIL PROTECTED] Vishal Patil [EMAIL PROTECTED] writes: : Could someone point me to an example that shows a SIMPLE network protocol : implemented over TCP/IP inside the FreeBSD kernel. I think I could look at : the NFS client driver but is there an example simpler than that. Also is : there a guide explaining how to go about developing TCP/IP based network : protocols for FreeBSD. [ to implement iSCSI in the kernel ] I'm unsure which side you wish to be on. There's accept filters that you can write, but I doubt that's what you want to do. This would be good if you are implementing an iSCSI target on FreeBSD, maybe (then again, maybe not). If you want to be an iSCSI initiator (I think that's the right term), then you'll need to do things similar to what sys/nfsclient/nfs_socket.c does. I could do a quick code walkthrough, but you'd likely be better off studying the nfs code since it will give you a better understanding than I can in a few lines. In addition, because locking has changed over time, the exact version matters. Careful study will show differences in what locks are needed, if any. But in a nutshell, you call socreate to get a socket. You setup the various fields in the socket data structures. You call sosetopt to do the latter. sobind will set this host's endpoint, and soconnect will connect the socket to the remote side. You'll need to setup send and receive buffers and manage them with soreceive and sosend. there's some callbacks that also need to be established as well. And some socket layer locking that may be exposed to your code because there are so few in-kernel protocol implementations that aren't peers to TCP, UDP or IP. I hope this helps. Warner ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to [EMAIL PROTECTED]
