LSL Protocol/Restrained Love Relay/Specification

Restrained Love Relay

VERSION 1.100

Written and maintained by Marine Kelley.


Audience

This document is meant for people who want to create or modify in-world objects to use the features of someone else's RestrainedLove viewer, typically cages and pieces of furniture, which per definition are usually not owned by that person.


Introduction

The RestrainedLove viewer only executes commands issued through llOwnerSay () messages. Therefore, in order to issue commands to someone using the viewer who does not own the object, that person must wear an attachment that relays commands after some security checks.


Why this spec ?

Many cages and furniture creators are interested in using its features such as sit, outfit, tp etc. These objects can be found in public places, or owned by friends... but as they are usually not owned by the user, the relay has to implement some basic security in order to avoid griefing. On top of it, the user does not want to be forced to switch to another relay when going to the next piece of furniture.

This is the purpose of this specification: To lay common rules so all the relays implementing it are compatible with all the furniture implementing it too. Without such a specification, one cage/furniture would talk to the relay specifically made to operate with it and that's all, eventually making the creator stay behind because people rather use standard objects than proprietary closed ones.

Basic principle

Here is a sample use case:

  1. User is wearing a Relay
  2. User enters a cage in a public area
  3. Cage sends a chat message on a known private channel (for instance "@tploc=n")
  4. Relay receives the message, decides to repeat the command to the user and blocks their ability to teleport from the map with an llOwnerSay ("@tploc=n");
  5. User is allowed to get out after some time, the cage issues a "!release" command

Without the relay, the cage could never prevent the user from teleporting since it doesn't belong to them.

Requirements

Here are the informal requirements for a relay (formal requirements below).


Security

Any object sending commands over the channel the relay listens to is likely to harm the user if there is no security implemented in the former. For instance, one could rez an object that sends a "@remoutfit=force" command over the chat channel to force an avatar to get naked in front of everyone without a warning. Of course nobody wants that, so basic security is needed.


User-friendliness

Security often implies control (access lists, switch, permissions...) so the user must be given some basic control over what kind of objects are allowed to issue commands.


Versatility

Some users will prefer wearing a dedicated attachment that they can unwear any time they want, others will be required to have the relay locked on them so they cannot detach them, others will want the script only... It is important to keep those differences in mind when deciding about the permissions of the relay. However, it is the user's responsibility to choose the relay that suits their needs best.


Licensing

According to the level of complexity and support of the relay, the creator is allowed to either provide it for free (open/close source) or to sell it, as long as it implements all the formal requirements.


Common questions

How hard is it to implement such a specification?

That depends on what you do. Furniture/cage makers will find it very easy for it only comes down to sending commands over a chat channel and getting feedback. Relay makers will find it harder but then again, that depends on the level of security and user-friendliness they wish to offer. But make no mistake, the relay is what does almost all the job (along with the viewer), because there will be many more kinds of furniture and cages than relays around.

Why do other people need to write such a relay?

Couldn't you write it yourself and publish it?

Of course I could, and there is even a working code for a basic relay at Reference Implementation. However:

The security and user-friendliness are the key parts here. Some users will prefer to be safe from griefing, others will prefer a good user interface, others will like a lot of features, others will want to move the script elsewhere... Everyone has their own tastes so there can be no one-size-fits-all relay.

Protocol

In-world objects send chat message over a channel (common to every relay and furniture), that the relay(s) acknowledges or not. If the message is a correct command and passes whatever security checks the relay implements, the latter repeats it as an llOwnerSay ().

When the session ends, possibly after several relogs, the object clears all the restrictions it has put the user under.


Example

Here is a basic example of messages exchanged between an avatar (id "9213...") and a world object (id "7adf...") : 

Object : CmdTest,9213f69a-ed7d-4a70-907a-7dba88c8831a,@tploc=n
Relay executes llOwnerSay ("@tploc=n");
Relay  : CmdTest,7adf6218-ab26-8566-8387-660133840794,@tploc=n,ok

Object : BunchoCommands,9213f69a-ed7d-4a70-907a-7dba88c8831a,@tploc=n|@tplm=n|@tplure=n|@remoutfit:shoes=force
Relay executes llOwnerSay ("@tploc=n");
Relay executes llOwnerSay ("@tplm=n");
Relay executes llOwnerSay ("@tplure=n");
Relay  : BunchoCommands,7adf6218-ab26-8566-8387-660133840794,@tploc=n,ok
Relay  : BunchoCommands,7adf6218-ab26-8566-8387-660133840794,@tplm=n,ok
Relay  : BunchoCommands,7adf6218-ab26-8566-8387-660133840794,@tplure=n,ok
Relay  : BunchoCommands,7adf6218-ab26-8566-8387-660133840794,@remoutfit:shoes=force,ko

After a relog :
Relay  : ping,7adf6218-ab26-8566-8387-660133840794,ping,ping
Object : ping,9213f69a-ed7d-4a70-907a-7dba88c8831a,!pong   (UUID found with llGetOwnerKey(id), where id is the sender-parameter of the listen-event)

Formal requirements

Common requirements to the Relay and the in-world object

In plain English :

"!release" meta-command

"!version" meta-command

"ping" relay message and "!pong" object meta-command

The relay message must be "ping,<object_uuid>,ping,ping" and the object message must be "ping,<user_uuid>,!pong". This allows the object to keep a listener open with a static filter, to reduce lag. <user_uuid> can be retrieved by a llGetOwnerKey() call.

Other meta-commands

The following meta-commands are deemed "optional" and relays do not have to implement them to be considered RLV compliant. They are mostly tied to the specific implementation of a particular relay that a particular furniture needs to interrogate. Furniture must not rely on the implementation of any of these commands to work.

"!implversion" meta-command

Deprecated meta-commands

The following meta-commands used to belong to the specification without much discussion and without permission. They are mentioned here for reference but never meant to be part of the specification. They might be reinstated one day if they prove themselves useful, but at the time of this writing it would make no sense to consider a relay to be out of spec if it didn't implement those meta-commands.

"!who" meta-command

Note from Marine : This meta-command may be designed to check the avatar operating the object to make griefing harder... but if this command is only as trustworthy as the object is, I don't see that as an improvement security-wise. Otherwise the idea has merit.

"!handover" meta-command

Note from Marine : This meta-command is particularly interesting, and is likely to go to the Other Meta-commands section in the future, or even in the main spec. It needs to be designed thoroughly first, though. I don't think it needs to be so complex, but it sure needs some checking.

Relay requirements

In-world object requirements

History

You can find the change history of this specification at Change History,