Open SLP Notes - Revision history

Nomis52 at 00:37, 3 December 2012

2012-12-03T00:37:12Z

← Older revision		Revision as of 00:37, 3 December 2012
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	Another problem with enqueuing the message buffer on to a socket-specific data structure is that if a retransmission event occurs, the message data isn't aged correctly. This generally works out since openslp retries quickly but it means lifetimes of services may vary across DAs.		Another problem with enqueuing the message buffer on to a socket-specific data structure is that if a retransmission event occurs, the message data isn't aged correctly. This generally works out since openslp retries quickly but it means lifetimes of services may vary across DAs.

			=== Default behavior is to run as root ===

			Unless you're careful about how you build slpd it runs as root. Some distros (Debian for one) appear to have fixed this.

	=== Interface Selection on Mac OS X ===		=== Interface Selection on Mac OS X ===

Nomis52 at 19:12, 2 December 2012

2012-12-02T19:12:06Z

← Older revision		Revision as of 19:12, 2 December 2012
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	Which means if you send a UDP packet less than 16 bytes, libslp spins in a loop trying to receive the rest of the data.		Which means if you send a UDP packet less than 16 bytes, libslp spins in a loop trying to receive the rest of the data.

			=== Lack of streaming new registations to a process on the same machine ===

			This was a must-have feature for me. I wanted a way to be updated immediately when new services appear on the network, instead of having to poll. Rather than calling SLPFindSrvs() it would be nice to have a mechanism to register interest in a particular service-type and then have a callback invoked whenever new SAs register with the DA. I could have added this functionality to openslp, but the lack of a regular releases meant that it was unlikely to make it out to user's machines by the time E1.33 shipped.

Nomis52 at 19:03, 2 December 2012

2012-12-02T19:03:29Z

← Older revision		Revision as of 19:03, 2 December 2012
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	Startup complete entering main run loop ...		Startup complete entering main run loop ...
	</pre>		</pre>

			=== Lack of Logging ===

			The 'logging' in slpd mostly consists of printing out the sent and receives SLP messages. This isn't helpful at all when trying to figure out why an SLP client isn't working correctly.

	=== Denial of Service against libslp ===		=== Denial of Service against libslp ===

Nomis52: /* = Race conditions during registration / deregistation */

2012-12-02T19:01:45Z

= Race conditions during registration / deregistation

← Older revision		Revision as of 19:01, 2 December 2012
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	Besides fixing the slpd code, the only way around this is to re-register less than 15 seconds before the expiry interval. For this reason I recommend the absolute minimum SLP lifetime used is 30s.		Besides fixing the slpd code, the only way around this is to re-register less than 15 seconds before the expiry interval. For this reason I recommend the absolute minimum SLP lifetime used is 30s.

	=== Race conditions during registration / deregistation ==		=== Race conditions during registration / deregistation ===

	The way the SA code works is something like this:		The way the SA code works is something like this:

Nomis52 at 01:58, 26 November 2012

2012-11-26T01:58:42Z

← Older revision		Revision as of 01:58, 26 November 2012
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	When I started working on the E1.33 project (RDMNet) one of the first things I did was search for an open source implementation of SLP. I came across http://www.openslp.org which looked promising since it's been ported to a variety of systems, and is backed by the likes of Novell / SuSE and of course, ETC. However since testing it, I've grown more disillusioned with the project, to the point where I honestly can't recommend it to anyone looking to implement E1.33		When I started working on the E1.33 project ([[RDMNet]]) one of the first things I did was search for an open source implementation of SLP. I came across http://www.openslp.org which looked promising since it's been ported to a variety of systems, and is backed by the likes of Novell / SuSE and of course, ETC. However since testing it, I've grown more disillusioned with the project, to the point where I honestly can't recommend it to anyone looking to implement E1.33

	This page has my notes on trying to get openslp working on a number of systems.		This page has my notes on trying to get openslp working on a number of systems.

Nomis52 at 01:58, 26 November 2012

2012-11-26T01:58:05Z

@@ Line 1: / Line 1: @@
-The last stable release of Open SLP was 1.2.1 in 2006. This page has my notes from getting this version working on a number of systems.
+When I started working on the E1.33 project (RDMNet) one of the first things I did was search for an open source implementation of SLP. I came across http://www.openslp.org which looked promising since it's been ported to a variety of systems, and is backed by the likes of Novell / SuSE and of course, ETC. However since testing it, I've grown more disillusioned with the project,  to the point where I honestly can't recommend it to anyone looking to implement E1.33
 === Registrations timing out too early ===
@@ Line 8: / Line 19: @@
 Besides fixing the slpd code, the only way around this is to re-register less than 15 seconds before the expiry interval. For this reason I recommend the absolute minimum SLP lifetime used is 30s.
 === Interface Selection on Mac OS X ===

66.92.11.32 at 17:10, 26 June 2011

2011-06-26T17:10:30Z

← Older revision		Revision as of 17:10, 26 June 2011
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	Startup complete entering main run loop ...		Startup complete entering main run loop ...
	</pre>		</pre>

			=== Denial of Service against libslp ===

			libslp has code like this:

			<pre>
			if(FD_ISSET(sockets->sock[i],&readfds)) {
			/* Peek at the first 16 bytes of the header */
			bytesread = recvfrom(sockets->sock[i],
			peek,
			16,
			MSG_PEEK,
			(struct sockaddr *)peeraddr,
			&peeraddrlen);
			printf(" read %d bytes\n", bytesread);
			if(bytesread == 16 \|\| ...) {

			}
			}
			</pre>

			Which means if you send a UDP packet less than 16 bytes, libslp spins in a loop trying to receive the rest of the data.

66.92.11.32 at 03:43, 20 June 2011

2011-06-20T03:43:06Z

← Older revision		Revision as of 03:43, 20 June 2011
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	slpd ages the registration database every 15 seconds (#define SLPD_AGE_INTERVAL 15) rather than tracking per registration timeouts. This means that your entry can timeout up to 15 seconds before it was supposed to.		slpd ages the registration database every 15 seconds (#define SLPD_AGE_INTERVAL 15) rather than tracking per registration timeouts. This means that your entry can timeout up to 15 seconds before it was supposed to.

	Besides fixing the slpd code, the only way around this is to re-register less than 15 seconds before the expiry interval.		Besides fixing the slpd code, the only way around this is to re-register less than 15 seconds before the expiry interval. For this reason I recommend the absolute minimum SLP lifetime used is 30s.

Nomis52 at 00:19, 20 June 2011

2011-06-20T00:19:43Z

← Older revision		Revision as of 00:19, 20 June 2011
Line 1:		Line 1:
	The last stable release of Open SLP was 1.2.1 in 2006. This page has my notes from getting this version working on a number of systems.		The last stable release of Open SLP was 1.2.1 in 2006. This page has my notes from getting this version working on a number of systems.


			=== Registrations timing out too early ===

			slpd ages the registration database every 15 seconds (#define SLPD_AGE_INTERVAL 15) rather than tracking per registration timeouts. This means that your entry can timeout up to 15 seconds before it was supposed to.

			Besides fixing the slpd code, the only way around this is to re-register less than 15 seconds before the expiry interval.

Nomis52 at 00:05, 20 June 2011

2011-06-20T00:05:28Z

← Older revision		Revision as of 00:05, 20 June 2011
Line 1:		Line 1:
	A stable release of Open SLP was 1.2.1 in 2006. This page has my notes from getting this version working on a number of systems.		The last stable release of Open SLP was 1.2.1 in 2006. This page has my notes from getting this version working on a number of systems.