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. You can find the change history at Change History.

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.
• Azoth Amat and Nano Siemens for helping to find a solution to the "force sit on login" problem
• Gregor Mougin for discovering and fixing the not-pong reply on login.

Reference Implementation

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

This version has a number of known bugs and a vulnerability. Please see Bugs and Pendings Features

<lsl>

//~ RestrainedLife Viewer Relay Script example code //~ By Marine Kelley //~ 2008-02-03 //~ 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 //~ 2008-06-24 fix of loophole in ask-mode by Felis Darwin //~ 2008-09-01 changed llSay to llShout, increased distance check (MK)

//~ 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 = 1020; // 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 = 100; // 100m is llShout 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) {

   llShout(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 llShout distance. It could have moved // before the message is received (chatlag) 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 FALSE;
   }

   // 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)lastForceSitDestination+"=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>