How to define new matcher function?

[M-Razavi]

I've written a function but now how should add it to function map?

public class InCollectionFunc extends AbstractFunction {
    public InCollectionFunc() {
    }

    public AviatorObject call(Map<String, Object> env, AviatorObject arg1, AviatorObject arg2, AviatorObject arg3) {
        String value = FunctionUtils.getStringValue(arg1, env);
        String collection = FunctionUtils.getStringValue(arg3, env);
        return AviatorBoolean.valueOf(isInCollection(value, collection));
    }

    private boolean isInCollection(String value,String collection) {
        System.out.println("value:" + value + " isIn collection:" + collection);
        return true;
    }

    public String getName() {
        return getNameStatic();
    }

    public static String getNameStatic() {
        return "isIn";
    }
}

enforcer = new Enforcer("erole.conf", "policy.csv");
enforcer.addFunction(InCollectionFunc.getNameStatic(),new InCollectionFunc());

[hsluoyz]

What you did now is correct, just call Enforcer.addFunction():

jcasbin/src/main/java/org/casbin/jcasbin/main/ManagementEnforcer.java

Lines 547 to 556 in e621f73

	/**
	* addFunction adds a customized function.
	*
	* @param name the name of the new function.
	* @param function the function.
	*/
	public void addFunction(String name, AviatorFunction function) {
	fm.addFunction(name, function);
	}
	}

It's very similar to Golang's Casbin, which is documented here: https://casbin.org/docs/en/syntax-for-models#how-to-add-a-customized-function

[M-Razavi]

I've used enforcer.addFunction() but got an error:
com.googlecode.aviator.exception.ExpressionSyntaxErrorException: Syntax error:Unexpect token 'isIn' at 32, current token: [type='variable',lexeme='isIn',index=32]. Parsing expression: r_act == "View" && r_obj.branch isIn^^

[hsluoyz]

Can you paste all your code here? including Enforcer setup, enforce() call, model text, policy text.

[M-Razavi]

This is set up and call :

enforcer = new Enforcer("role.conf", "policy.csv");
enforcer.addFunction(InCollectionFunc.getNameStatic(),new InCollectionFunc());
enforcer.addFunction(TimeValidityFunc.getNameStatic(),new TimeValidityFunc());
if (enforcer.enforce("cathy", "order1", "view")) {
        System.out.println("ok");
}

And this is model:

[request_definition]
r = sub, obj, act

[policy_definition]
p = sub, obj, act

[role_definition]
g = _, _

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = r.act == "View" && r.obj.branch isIn(r.sub.branch) || g(r.sub, "Manager") && r.act == "View" ||  isValidTimeForUser(r.sub) || g(r.sub, "Manager") && (r.act == "Confirm" || r.act == "Reject")  || g(r.sub, "Operator") && (r.act == "Create" || r.act == "Edit") || g(r.sub, "Reviewer") && r.obj.status== "confirmed"

Policy file is empty.

[M-Razavi]

Time function:

import com.googlecode.aviator.runtime.function.AbstractFunction;
import com.googlecode.aviator.runtime.function.FunctionUtils;
import com.googlecode.aviator.runtime.type.AviatorBoolean;
import com.googlecode.aviator.runtime.type.AviatorObject;

import java.time.LocalTime;
import java.util.Map;

/**
 * Created by Mahdi Razavi on 1/22/19-4:06 PM
 */
public class TimeValidityFunc extends AbstractFunction {

    public TimeValidityFunc() {
    }

    public AviatorObject call(Map<String, Object> env, AviatorObject arg1, AviatorObject arg2, AviatorObject arg3) {
        String actionTime = FunctionUtils.getStringValue(arg1, env);
        String validityTimeStart = FunctionUtils.getStringValue(arg2, env);
        String validityTimeEnd = FunctionUtils.getStringValue(arg3, env);
        return AviatorBoolean.valueOf(isTimeMatch(actionTime, validityTimeStart, validityTimeEnd));
//        return AviatorBoolean.valueOf(BuiltInFunctions.keyMatch(key1, key2));
    }


    private boolean isTimeMatch(String actionTime, String validityTimeStart, String validityTimeEnd) {
        LocalTime actTime = LocalTime.parse(actionTime);
        LocalTime tStart = LocalTime.parse(validityTimeStart);
        LocalTime tEnd = LocalTime.parse(validityTimeEnd);

        return actTime.compareTo(tStart) >= 0 && actTime.compareTo(tEnd) <= 0;

    }

    private boolean isValidTimeForUser(String userName) {
        System.out.println("User:" + userName + " wants to do action");

        return true;
    }

    public String getName() {
        return getNameStatic();
    }

    public static String getNameStatic() {
        return "isValidTimeForUser";
    }
}

and isIn function

import com.googlecode.aviator.runtime.function.AbstractFunction;
import com.googlecode.aviator.runtime.function.FunctionUtils;
import com.googlecode.aviator.runtime.type.AviatorBoolean;
import com.googlecode.aviator.runtime.type.AviatorObject;

import java.time.LocalTime;
import java.util.Map;

/**
 * Created by Mahdi Razavi on 1/22/19-4:06 PM
 */
public class InCollectionFunc extends AbstractFunction {

    public InCollectionFunc() {
    }

    public AviatorObject call(Map<String, Object> env, AviatorObject arg1, AviatorObject arg2, AviatorObject arg3) {
        String value = FunctionUtils.getStringValue(arg1, env);
        String collection = FunctionUtils.getStringValue(arg3, env);
        return AviatorBoolean.valueOf(isInCollection(value, collection));
    }



    private boolean isInCollection(String value,String collection) {
        System.out.println("value:" + value + " isIn collection:" + collection);

        return true;
    }

    public String getName() {
        return getNameStatic();
    }

    public static String getNameStatic() {
        return "isIn";
    }


}

[hsluoyz]

Your matcher is not correct. From your function's code, it has three arguments: AviatorObject arg1, AviatorObject arg2, AviatorObject arg3. BTW, I didn't see you are using the 2nd arg.

So your matcher should be: isIn(arg1, arg2, arg3) instead of r.obj.branch isIn(r.sub.branch).

[M-Razavi]

@hsluoyz Many Thanks

[M-Razavi]

I got this error:
Could not find variable r_obj.branch
@hsluoyz How should I set the field of request variable?

[M-Razavi]

I think this is a bug in aviator which I fixed it
killme2008/aviatorscript#106

[hsluoyz]

What does that PR mean? I'm not a Java expert and didn't quite understand it.

BTW, I already asked Aviator's author to review your PR :)

[M-Razavi]

It seems that recent commit merged in Aviator and it needed to use the latest version of it in JCasbin dependency.

[hsluoyz]

@M-Razavi Aviator needs to release a new version before jCasbin can import it. You can ask its author to release one and I will release a new version jCasbin based on it.

[hsluoyz]

@M-Razavi jCasbin 1.2.0 has been released to Maven, may need some time for cache: https://mvnrepository.com/artifact/org.casbin/jcasbin