nullPointer at Enforcer

[amelleHamouch]

It doesn't reach the condition , when I instanciate the Enforcer I immediatly entre the exception , please help

[hsluoyz]

Can you debug it and find the crashing line?

[amelleHamouch]

Line 69 , Enforcer enforcer = new Enforcer(tempConfPath, tempPoliciesPath);
says the enforcer is null

[hsluoyz]

I can't squeeze out a bit information time to time like this. Can you provide a full working and runnable example to reproduce?

[amelleHamouch]

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package com.kapiasolutions.karma.filter;

import com.kapiasolutions.karma.util.LogUtil;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.core.CacheControl;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.Provider;
import org.casbin.jcasbin.main.Enforcer;

/**
*

• @author ahamouch
  */
  @Provider
  public class JCasbinFilter implements ContainerRequestFilter {

  String conf;
  String policies;
  String key = "";

  @OverRide
  public void filter(ContainerRequestContext crc) throws IOException {

   try {
       InitialContext initialContext = new InitialContext();
       Context environmentContext = (Context) initialContext.lookup("java:/comp/env");
       configureCasbinFiles(environmentContext);
       UriInfo uriInfo = crc.getUriInfo();
       Request request = crc.getRequest();
       String requestPath = uriInfo.getPath();
       int index = requestPath.lastIndexOf("/");
       String object = requestPath.substring(index);
       String verb = request.getMethod();
       String domain = requestPath.replace(object, "");
       String confContent = decryptFile(key, conf);
       String polContent = decryptFile(key, policies);
  
       // adresse des fichier temporaires
       String tempConfPath = writeTempFile(confContent, conf);
       String tempPoliciesPath = writeTempFile(polContent, policies);
  
       //Utilisation de Enforcer de Casbin en lui passant les informations récupéré sur la requête
       Enforcer enforcer = new Enforcer(tempConfPath, tempPoliciesPath);
       //Si False accès non autorisé , requête annulée , envoi de la invalidAccessLevelResponse
       if (enforcer.enforce(object, domain, verb) == false) {
           String msg = String.format("You are not allowed to access this service", requestPath);
           CacheControl cc = new CacheControl();
           cc.setNoStore(true);
           Response invalidAccessLevelResponse = Response.status(Response.Status.FORBIDDEN)
                   .entity(msg)
                   .cacheControl(cc)
                   .build();
           crc.abortWith(invalidAccessLevelResponse);
       }
  
   } catch (NamingException ex) {
       LogUtil.showLog(ex);
   } catch (Exception ex) {
       Logger.getLogger(JCasbinFilter.class.getName()).log(Level.SEVERE, null, ex);
   }
  

  }

  //Création de la Réponse en cas d'accès refusé
  //Configuration de Casbin via les variables d'environnement
  private void configureCasbinFiles(Context environmentContext) throws NamingException {

   this.conf = (String) environmentContext.lookup("casbinConf");
   this.policies = (String) environmentContext.lookup("casbinPolicies");
  

  }

  //Lecture et récupération des données cryptées
  public static byte[] readCasbinFile(String path) throws Exception {

   byte[] encoded;
   encoded = Files.readAllBytes(Paths.get(path));
   return encoded;
  

  }

  //Génération de la clé à partir du String
  public static SecretKey generateKey(String keyStr) throws NoSuchAlgorithmException {
  KeyGenerator keygen = KeyGenerator.getInstance("AES");
  SecureRandom random = new SecureRandom(keyStr.getBytes());
  keygen.init(random);
  SecretKey secretKey = keygen.generateKey();
  return secretKey;
  }

  //Le fichier est décrypté ici
  public String decryptFile(String key, String path) throws Exception {
  SecretKey secretkey = generateKey(key);
  byte[] cipherText = readCasbinFile(path);
  byte[] IV = new byte[16];
  Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
  SecretKeySpec keySpec = new SecretKeySpec(secretkey.getEncoded(), "AES");
  IvParameterSpec ivSpec = new IvParameterSpec(IV);
  cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
  byte[] decryptedText = cipher.doFinal(cipherText);
  String decrypt = new String(decryptedText);

   return decrypt;
  

  }

  //Création du fichier temporaire de config Casbin
  public String writeTempFile(String contentConf, String confFilePath) throws IOException {

   if (confFilePath.contains("model.conf")) {
       String tempPath = confFilePath.replace("model.conf", "tempModel.conf");
  
       FileWriter writer = new FileWriter(tempPath, false);
       writer.write(contentConf);
       writer.close();
       return tempPath;
   } else {
       String tempPath = confFilePath.replace("karma.policy", "Tempkarma.policy");
       FileWriter writer = new FileWriter(tempPath, false);
       writer.write(contentConf);
       writer.close();
       return tempPath;
   }
  

  }
  }

[hsluoyz]

It's better in a GitHub repo, with project files, POM file, etc. So I can run it at once without copy-paste and setup a lot of code.

[amelleHamouch]

eh ..I don't have the right to share this code unfortunately ><

[hsluoyz]

You should provide a minimized example, only show the bug.

[dimi-nk]

I bumped into a similar issue last night. The code that parses the policy.csv expects everything to be delimited with ", " and nothing else. I'll make a PR to make that a bit more lenient.