LSL Protocol/Restrained Love Relay/Reference Implementation

This particular example that anyone can distribute freely as open-source only (you are not allowed to sell this code) and including the header comments is just meant to give an idea of how a relay basically works.

What it does

• Implements the specification described hereabove.
• Commented to facilitate reading and learning.
• Tested and working with test objects and with real cages.

What it doesn't do

• Error-checking.
• Access lists.
• Lock on the avatar.
• Handle more than one object.
• Reject some commands by nature.
• And so much more that makes good scripts stand out in the crowd.

How to use it

• Create a prim in which you put a script containing this code (don't forget to name it correctly by following the "RLVnnn" requirement).
• Wear the prim, it says its current on/off status
• Click on the prim to switch from "Off" to "On with permission" to "On without permission" and back to "Off"
• Find an object that implements this specification and test.

Special thanks

• Chorazin Allen for reviewing the code, giving ideas, coding and re-coding his own scripts to make sure everything works properly between the relay and the cage, and for not killing me every time I change my mind here and there on the spec.

Reference Implementation

Please add fixes, new features and stuff like that to Development & Contribution.

<lsl>

//~ RestrainedLife Viewer Relay Script example code //~ By Marine Kelley //~ 2008-02-03 //~ v1.1 //~ 2008-02-16 with fixes by Maike Short //~ 2008-02-24 more fixes by Maike Short //~ 2008-03-03 code cleanup by Maike Short //~ 2008-03-05 silently ignore commands for removing restrictions if they are not active anyway

//~ This code is provided AS-IS, OPEN-SOURCE and holds NO WARRANTY of accuracy, //~ completeness or performance. It may only be distributed in its full source code, //~ this header and disclaimer and is not to be sold.

//~ * Possible improvements //~ Do some error checking //~ Handle more than one object //~ Periodically check that the in-world objects are still around, when one is missing purge its restrictions //~ Manage an access list //~ Reject some commands if not on access list (force remove clothes, force remove attachments...) //~ and much more...

// --------------------------------------------------- // Constants // ---------------------------------------------------

integer RLVRS_PROTOCOL_VERSION = 1014; // version of the protocol, stated on the specification page

string PREFIX_RL_COMMAND = "@"; string PREFIX_METACOMMAND = "!";

integer RLVRS_CHANNEL = -1812221819; // RLVRS in numbers integer DIALOG_CHANNEL = -1812220409; // RLVDI in numbers

integer MAX_OBJECT_DISTANCE = 20; // 20m is llSay distance integer MAX_TIME_AUTOACCEPT_AFTER_FORCESIT = 300; // 300 is 5 minutes

integer PERMISSION_DIALOG_TIMEOUT = 30;

integer LOGIN_DELAY_WAIT_FOR_PONG = 10; integer LOGIN_DELAY_WAIT_FOR_FORCE_SIT = 60;

integer MODE_OFF = 0; integer MODE_ASK = 1; integer MODE_AUTO = 2;

// --------------------------------------------------- // Variables // ---------------------------------------------------

integer nMode;

list lRestrictions; // restrictions currently applied (without the "=n" part) key kSource; // UUID of the object I'm commanded by, always equal to NULL_KEY if lRestrictions is empty, always set if not

string sPendingName; // name of initiator of pending request (first request of a session in mode 1) key sPendingId; // UUID of initiator of pending request (first request of a session in mode 1) string sPendingMessage; // message of pending request (first request of a session in mode 1) integer sPendingTime;

// used on login integer timerTickCounter; // count the number of time events on login (forceSit has to be delayed a bit) integer loginWaitingForPong; integer loginPendingForceSit;

key lastForceSitDestination; integer lastForceSitTime;

// --------------------------------------------------- // Low Level Communication // ---------------------------------------------------

debug(string x) { // llOwnerSay("DEBUG: " + x); }

// acknowledge or reject ack(string cmd_id, key id, string cmd, string ack) {

   llSay(RLVRS_CHANNEL, cmd_id + "," + (string)id + "," + cmd + "," + ack);

}

// cmd begins with a '@' sendRLCmd(string cmd) {

   llOwnerSay(cmd);

}

// get current mode as string string getModeDescription() {

   if (nMode == 0) return "RLV Relay is OFF"; 
   else if (nMode == 1) return "RLV Relay is ON (permission needed)"; 
   else return "RLV Relay is ON (auto-accept)"; 

}

// check that this command is for us and not someone else integer verifyWeAreTarget(string message) {

   list tokens = llParseString2List(message, [","], []);
   if (llGetListLength(tokens) == 3) // this is a normal command
   {
     if (llList2String(tokens, 1) == llGetOwner()) // talking to me ?
     {
        return TRUE;
     }
   }
   return FALSE;

}

// --------------------------------------------------- // Permission Handling // ---------------------------------------------------

// are we already under command by this object? integer isObjectKnow(key id) {

   // first some error handling
   if (id == NULL_KEY)
   {
       return FALSE;
   }

   // are we already under command by this object?
   if (kSource == id)
   {
       return TRUE;
   }

   // are we not under command by any object but were we forced to sit on this object recently?
   if ((kSource == NULL_KEY) && (id == lastForceSitDestination))
   {
       debug("on last force sit target");
       if (lastForceSitTime + MAX_TIME_AUTOACCEPT_AFTER_FORCESIT > llGetUnixTime())
       {
           debug("and recent enough to auto accept");
           return TRUE;
       }
   }

   return FALSE;

}

// check whether the object is in llSay distance. // The specification requires llSay instead of llShout or llRegionSay // to be used to limit the range. But this has to be checked here again // because the objects are not trustworthy. integer isObjectNear(key id) {

   vector myPosition = llGetRootPosition();
   list temp = llGetObjectDetails(id, ([OBJECT_POS]));
   vector objPostition = llList2Vector(temp,0);
   float distance = llVecDist(objPostition, myPosition);
   return distance <= MAX_OBJECT_DISTANCE;

}

// do a basic check on the identity of the object trying to issue a command integer isObjectIdentityTrustworthy(key id) {

   key parcel_owner=llList2Key (llGetParcelDetails (llGetPos (), [PARCEL_DETAILS_OWNER]), 0);
   key parcel_group=llList2Key (llGetParcelDetails (llGetPos (), [PARCEL_DETAILS_GROUP]), 0);
   key object_owner=llGetOwnerKey(id);
   key object_group=llList2Key (llGetObjectDetails (id, [OBJECT_GROUP]), 0);

   debug("owner= " + (string) parcel_owner + " / " + (string) object_owner);
   debug("group= " + (string) parcel_group + " / " + (string) object_group);

   if (object_owner==llGetOwner ()        // IF I am the owner of the object
     || object_owner==parcel_owner        // OR its owner is the same as the parcel I'm on
     || object_group==parcel_group        // OR its group is the same as the parcel I'm on
   )
   {
       return TRUE;
   }
   return FALSE;

}

// Is this a simple request for information or a meta command like !release? integer isSimpleRequest(list list_of_commands) {

   integer len = llGetListLength(list_of_commands);
   integer i;

   // now check every single atomic command
   for (i=0; i < len; ++i)
   {
       string command = llList2String(list_of_commands, i);
       if (!isSimpleAtomicCommand(command))
       {
          return FALSE;
       }
   }

   // all atomic commands passed the test
   return TRUE;

}

// is this a simple atmar command // (a command which only queries some information or releases restrictions) // (e. g.: cmd ends with "=" and a number (@version, @getoutfit, @getattach) or is a !-meta-command) integer isSimpleAtomicCommand(string cmd) {

   // check right hand side of the "=" - sign
   integer index = llSubStringIndex (cmd, "=");
   if (index > -1) // there is a "=" 
   {
       // check for a number after the "="
       string param = llGetSubString (cmd, index + 1, -1);
       if ((integer)param!=0 || param=="0") // is it an integer (channel number)?
       {
           return TRUE;
       }

       // removing restriction
       if ((param == "y") || (param == "rem"))
       {
           return TRUE;
       }
   }

   // check for a leading ! (meta command)
   if (llSubStringIndex(cmd, PREFIX_METACOMMAND) == 0)
   {
       return TRUE;
   }

   // check for @clear
   // Note: @clear MUST NOT be used because the restrictions will be reapplied on next login
   // (but we need this check here because "!release|@clear" is a BROKEN attempt to work around
   // a bug in the first relay implementation. You should refuse to use relay versions < 1013
   // instead.)
   if (cmd == "@clear")
   {
       return TRUE;
   }
 
   // this one is not "simple".
   return FALSE;

}

// If we already have commands from this object pending // because of a permission request dialog, just add the // new commands at the end. // Note: We use a timeout here because the player may // have "ignored" the dialog. integer tryToGluePendingCommands(key id, string commands) {

   if ((sPendingId == id) && (sPendingTime + PERMISSION_DIALOG_TIMEOUT > llGetUnixTime()))
   {
       debug("Gluing " + sPendingMessage + " with " + commands);
       sPendingMessage = sPendingMessage + "|" + commands;
       return TRUE;
   }
   return FALSE;

}

// verifies the permission. This includes mode // (off, permission, auto) of the relay and the // identity of the object (owned by parcel people). integer verifyPermission(key id, string name, string message) {

   // is it switched off?
   if (nMode == MODE_OFF)
   {
       return FALSE;
   }

   // extract the commands-part
   list tokens = llParseString2List (message, [","], []);
   if (llGetListLength (tokens) < 3)
   {
       return FALSE;
   }
   string commands = llList2String(tokens, 2);
   list list_of_commands = llParseString2List(commands, ["|"], []);

   // accept harmless commands silently
   if (isSimpleRequest(list_of_commands))
   {
       return TRUE;
   }

   // if we are already having a pending permission-dialog request for THIS object,
   // just add the new commands at the end of the pending command list.
   if (tryToGluePendingCommands(id, commands))
   {
       return TRUE;
   }

   // check whether this object belongs here
   integer trustworthy = isObjectIdentityTrustworthy(id);
   string warning = "";
   if (!trustworthy)
   {
       warning = "\n\nWARNING: This object is not owned by the people owning this parcel. Unless you know the owner, you should deny this request.";
   }

   // ask in permission-request-mode and/OR in case the object identity is suspisous.
   if (nMode == MODE_ASK || !trustworthy)
   {
       sPendingId=id;
       sPendingName=name;
       sPendingMessage=message;
       sPendingTime = llGetUnixTime();
       llDialog (llGetOwner(), name + " would like control your viewer." + warning + ".\n\nDo you accept ?", ["Yes", "No"], DIALOG_CHANNEL);
       debug("Asking for permission");
       return FALSE;
   }
   return TRUE;

}

// --------------------------------------------------- // Executing of commands // ---------------------------------------------------

// execute a non-parsed message // this command could be denied here for policy reasons, (if it were implemenetd) // but this time there will be an acknowledgement execute(string name, key id, string message) {

   list tokens=llParseString2List (message, [","], []);
   if (llGetListLength (tokens)==3) // this is a normal command
   {
       string cmd_id=llList2String (tokens, 0); // CheckAttach
       key target=llList2Key (tokens, 1); // UUID
       if (target==llGetOwner ()) // talking to me ?
       {
           list list_of_commands=llParseString2List (llList2String (tokens, 2), ["|"], []);
           integer len=llGetListLength (list_of_commands);
           integer i;
           string command;
           string prefix;
           for (i=0; i<len; ++i) // execute every command one by one
           {
               // a command is a RL command if it starts with '@' or a metacommand if it starts with '!'
               command=llList2String (list_of_commands, i);
               prefix=llGetSubString (command, 0, 0);

               if (prefix==PREFIX_RL_COMMAND) // this is a RL command
               {
                   executeRLVCommand(cmd_id, id, command);
               }
               else if (prefix==PREFIX_METACOMMAND) // this is a metacommand, aimed at the relay itself
               {
                   executeMetaCommand(cmd_id, id, command);
               }
           }
       }
   }

}

// executes a command for the restrained life viewer // with some additinal magic like book keeping executeRLVCommand(string cmd_id, string id, string command) {

   // we need to know whether whether is a rule or a simple command
   list tokens_command=llParseString2List (command, ["="], []);
   string behav=llList2String (tokens_command, 0); // @getattach:skull
   string param=llList2String (tokens_command, 1); // 2222
   integer ind=llListFindList (lRestrictions, [behav]);

   if (param=="n" || param=="add") // add to lRestrictions
   {
       if (ind<0) lRestrictions+=[behav];
       kSource=id; // we know that kSource is either NULL_KEY or id already
   }
   else if (param=="y" || param=="rem") // remove from lRestrictions
   {
       if (ind>-1) lRestrictions=llDeleteSubList (lRestrictions, ind, ind);
       if (llGetListLength (lRestrictions)==0) kSource=NULL_KEY;
   }

   workaroundForAtClear(command);
   rememberForceSit(command);
   sendRLCmd(command); // execute command
   ack(cmd_id, id, command, "ok"); // acknowledge

}

// check for @clear // Note: @clear MUST NOT be used because the restrictions will be reapplied on next login // (but we need this check here because "!release|@clear" is a BROKEN attempt to work around // a bug in the first relay implementation. You should refuse to use relay versions < 1013 // instead.) workaroundForAtClear(string command) {

   if (command == "@clear")
   {
       releaseRestrictions();
   }

}

// remembers the time and object if this command is a force sit rememberForceSit(string command) {

   list tokens_command=llParseString2List (command, ["="], []);
   string behav=llList2String (tokens_command, 0); // @sit:<uuid>
   string param=llList2String (tokens_command, 1); // force
   if (param != "force")
   {
       return;
   }

   tokens_command=llParseString2List(behav, [":"], []);
   behav=llList2String (tokens_command, 0); // @sit
   param=llList2String (tokens_command, 1); // <uuid>
   debug("'force'-command:" + behav + "/" + param);
   if (behav != "@sit")
   {
       return;
   }
   lastForceSitDestination = (key) param;
   lastForceSitTime = llGetUnixTime();
   debug("remembered force sit");

}

// executes a meta command which is handled by the relay itself executeMetaCommand(string cmd_id, string id, string command) {

   if (command==PREFIX_METACOMMAND+"version") // checking relay version
   {
       ack(cmd_id, id, command, (string)RLVRS_PROTOCOL_VERSION);
   }
   else if (command==PREFIX_METACOMMAND+"release") // release all the restrictions (end session)
   {
       releaseRestrictions();
       ack(cmd_id, id, command, "ok");
   }

}

// lift all the restrictions (called by !release and by turning the relay off) releaseRestrictions () {

   kSource=NULL_KEY;
   integer i;
   integer len=llGetListLength (lRestrictions);
   for (i=0; i<len; ++i)
   {
       sendRLCmd(llList2String (lRestrictions, i)+"=y");
   }
   lRestrictions = [];
   loginPendingForceSit = FALSE;

}

// --------------------------------------------------- // initialisation and login handling // ---------------------------------------------------

init() {

   nMode=1;
   kSource=NULL_KEY;
   lRestrictions=[];
   sPendingId=NULL_KEY;
   sPendingName="";
   sPendingMessage="";
   llListen (RLVRS_CHANNEL, "", "", "");
   llListen (DIALOG_CHANNEL, "", llGetOwner(), "");
   llOwnerSay (getModeDescription());

}

// sends the known restrictions (again) to the RL-viewer // (call this functions on login) reinforceKnownRestrictions() {

   integer i;
   integer len=llGetListLength(lRestrictions);
   string restr;
   debug("kSource=" + (string) kSource);
   for (i=0; i<len; ++i)
   {
       restr=llList2String(lRestrictions, i);
       debug("restr=" + restr);
       sendRLCmd(restr+"=n");
       if (restr=="@unsit")
       {
           loginPendingForceSit = TRUE;
       }
   }

}

// send a ping request and start a timer pingWorldObjectIfUnderRestrictions() {

   loginWaitingForPong = FALSE;
   if (kSource != NULL_KEY)
   {
       ack("ping", kSource, "ping", "ping");
       timerTickCounter = 0;
       llSetTimerEvent(1.0);
       loginWaitingForPong = TRUE;
   }

}

default {

   state_entry()
   {
       init();
   }

   on_rez(integer start_param)
   {
       // relogging, we must refresh the viewer and ping the object if any
       // if mode is not OFF, fire all the stored restrictions
       if (nMode)
       {
           reinforceKnownRestrictions();
           pingWorldObjectIfUnderRestrictions();
       }
       // remind the current mode to the user
       llOwnerSay(getModeDescription());
   }

   timer()
   {
       timerTickCounter++;
       debug("timer (" + (string) timerTickCounter + "): waiting for pong: " + (string) loginWaitingForPong + " pendingForceSit: " + (string) loginPendingForceSit);
       if (loginWaitingForPong && (timerTickCounter == LOGIN_DELAY_WAIT_FOR_PONG))
       {
           llWhisper(0, "Lucky Day: " + llKey2Name(llGetOwner()) + " is freed because the device is not available.");
           loginWaitingForPong = FALSE;
           loginPendingForceSit = FALSE;
           releaseRestrictions();
       }

       if (loginPendingForceSit)
       {
           integer agentInfo = llGetAgentInfo(llGetOwner());
           if (agentInfo & AGENT_SITTING)
           {
               loginPendingForceSit = FALSE;
               debug("is sitting now");
           }
           else if (timerTickCounter == LOGIN_DELAY_WAIT_FOR_FORCE_SIT)
           {
               llWhisper(0, "Lucky Day: " + llKey2Name(llGetOwner()) + " is freed because sitting down again was not possible.");
               loginPendingForceSit = FALSE;
               releaseRestrictions();
           }
           else
           {
                sendRLCmd ("@sit:"+(string)kSource+"=force");
           }
       }

       if (!loginPendingForceSit && !loginWaitingForPong)
       {
           llSetTimerEvent(0.0);
       }
   }

   listen(integer channel, string name, key id, string message)
   {
       if (channel==RLVRS_CHANNEL)
       {
           if (!verifyWeAreTarget(message))
           {
              return;
           }
       
           if (nMode== MODE_OFF)
           {
               debug("deactivated - ignoring commands");
               return; // mode is 0 (off) => reject
           }
           if (!isObjectNear(id)) return;

           debug("Got message (active world object " + (string) kSource + "): name=" + name+ "id=" + (string) id + " message=" + message);

           if (kSource != NULL_KEY && kSource != id)
           {
               debug("already used by another object => reject");
               return;
           }

           loginWaitingForPong = FALSE; // whatever the message, it is for me => it satisfies the ping request

           if (!isObjectKnow(id))
           {
               debug("asking for permission because kSource is NULL_KEY");
               if (!verifyPermission(id, name, message))
               {
                   return;
               }
           }

           debug("Executing: " + (string) kSource);
           execute(name, id, message);
       }
       else if (channel==DIALOG_CHANNEL)
       {
           if (id != llGetOwner())
           {
               return; // only accept dialog responses from the owner
           }
           if (sPendingId!=NULL_KEY)
           {
               if (message=="Yes") // pending request authorized => process it
               {
                   execute(sPendingName, sPendingId, sPendingMessage);
               }

               // clear pending request
               sPendingName="";
               sPendingId=NULL_KEY;
               sPendingMessage="";
           }
       }
   }

   touch_start(integer num_detected)
   {
       // touched by user => cycle through OFF/ON_PERMISSION/ON_ALWAYS modes
       key toucher=llDetectedKey(0);
       if (toucher==llGetOwner())
       {
           if (kSource != NULL_KEY)
           {
               llOwnerSay("Sorry, you cannot change the relay mode while it is locked.");
               return;
           }
           ++nMode;
           if (nMode>2) nMode=0;
           if (nMode==MODE_OFF) releaseRestrictions ();
           llOwnerSay (getModeDescription());
       }
   }

   changed(integer change)
   {
       if (change & CHANGED_OWNER) 
       {
            llResetScript();
       }
   }

} </lsl>

History

1.014

• improved compatibility with existing world objects and simplified the world-object coding
  • commands to remove non-existing restrictions must be ignored silently by the relay (without spamming the user with pointless request-for-permission dialog)
  • simple (harmless) commands can now be joined in one single message without triggering the permission dialog.
  • multiple pending messages from the same object are now stored over the permission dialog.

1.013e: no changes in the specificiation, just in the sample code

• Verified how far away the object is that is trying to control you. The specification says that the object must use llSay for 20meters max range. But as the object is not trustworth this must be checked in the relay again.Previously llShout (for 100 meters) and llRegionSay (for the complete sim) did work, too.
• the permission request dialog was shown even if the command was for another person
• the ping/pong on login did not verify whether the pong event was for us and not some other person.
• fixed a problem which caused additional questions for permission dialogs
• now automatically accepts commands from an object you were forced to sit on by the relay (so you only have to confirm that once)
• fixed force sit on re-login which could fail if the login was very slow
• code cleanup

1.013

• fixed force-sit on login (by delaying it for 10 seconds)
• allow meta commands without asking for permission
• fixed a vulnerability which allowed faked responses for the permission dialog
• extended object identity check for the object/parcel owner (before it checked only the group but there is groupless personal property out there)
• prevent turning off of the relay when it is locked

1.012 Fixed a bug in !release which caused the relay to reapply those restrictions on login for the object NULL_KEY. But as there is no ping/pong for NULL_KEY the wearer was stuck.

1.011 Precision on the ping-pong routine : relay standard message would be "ping,<object_uuid>,ping,ping" so objects can keep a listener with a static filter, to reduce lag. Thank you again Monica Jewell for the suggestion.

1.010 Added the ping-pong routine as a way to ensure the object is still available when the user relogs. Also updated the sample code to handle the timeout. Thank you Monica Jewell for pointing that possible problem out.

1.000 First release