# MultiSessionAppserverSecurityManager.java

    /*
    ** Module   : MultiSessionAppserverSecurityManager.java
    ** Abstract : Multi-session agent appserver security manager.
    **
    ** Copyright (c) 2025, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description----------------------------------
    ** 001 GBB 20250122 Created initial version.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
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    **     the covered work, without written authorization.
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    **
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    **     versions of the covered work must be marked in a reasonable way to make it
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    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */
    package com.goldencode.p2j.security;

    import com.goldencode.p2j.util.*;
    import com.goldencode.p2j.util.logging.*;

    import java.util.*;
    import java.util.concurrent.*;
    import java.util.concurrent.atomic.*;

    /** Multi-session agent appserver security manager. */
    public class MultiSessionAppserverSecurityManager
    {
       /** Initialization on demand idiom singleton holder */
       private static class SingletonHolder
       {
          /** Singleton instance */
          private static final MultiSessionAppserverSecurityManager INSTANCE = new MultiSessionAppserverSecurityManager();
       }

       /** Logger. */
       private static final CentralLogger LOG = CentralLogger.get(MultiSessionAppserverSecurityManager.class);

       /**
        * Executor used to cleanup SecurityContext, when the appserver app is terminated. The executor uses a
        * factory for threads with the right initial context to be able to perform the tasks.
        */
       private static final Executor contextCleanupExecutor = Executors.newSingleThreadExecutor(
          runnable -> new Thread(runnable, "MSA Context Cleanup Thread")
          {
             @Override
             public void run()
             {
                try
                {
                   setInitialContext();
                }
                catch (RestrictedUseException e)
                {
                   LOG.warning("Couldn't set initial context on thread " + Thread.currentThread().getName(), e);
                }
                super.run();
             }
          }
       );

       /** Map of the security contexts by appserver */
       private final Map<String, Map<Integer, SecurityContext>> appContextMaps = new ConcurrentHashMap<>();

       /**
        * Map of the context id counters by appserver. The ids are ordinal number starting at 1. If multi-session
        * agents are implemented, the counters should be separate for each agent.
        */
       private final Map<String, AtomicInteger> appContextIdCounters = new ConcurrentHashMap<>();

       /**
        * Static method for access to the singleton instance of the manager
        *
        * @return   The singleton instance of the manager
        */
       public static MultiSessionAppserverSecurityManager getInstance()
       {
          return SingletonHolder.INSTANCE;
       }

       /**
        * Sets the initial security context on the thread.
        *
        * @throws   RestrictedUseException
        *           If called from an unexpected caller.
        */
       public static void setInitialContext()
       throws RestrictedUseException
       {
          SecurityManager.getInstance().contextSm.setUniqueInitialSecurityContext();
       }

       /**
        * Creates a new SecurityContext with an incremental id for this application, and saves a reference to
        * the context.
        *
        * @param    appName
        *           The appserver app name.
        * @param    processId
        *           The FWD process account id.
        *
        * @return   The id of the newly created context.
        *
        * @throws   RestrictedUseException
        *           If called from an unexpected caller.
        */
       public int createContext(String appName, String processId)
       throws RestrictedUseException
       {
          // restrict the use of this method
          SecurityUtil.checkCallerAbort(new String[]
          {
             "com.goldencode.p2j.util.appserver.MultiSessionAppserver.createSession"
          });

          SecurityManager sm = SecurityManager.getInstance();

          SecurityContext newContext = null;
          try
          {
             newContext = sm.contextSm.createSecurityContext(sm.getCache(), processId, null);
          }
          catch (RestrictedUseException e)
          {
             LOG.warning("", e);
          }

          if (!appContextIdCounters.containsKey(appName))
          {
             appContextIdCounters.put(appName, new AtomicInteger(1));
          }
          int contextId = appContextIdCounters.get(appName).getAndIncrement();

          if (!appContextMaps.containsKey(appName))
          {
             appContextMaps.put(appName, new HashMap<Integer, SecurityContext>());
          }
          appContextMaps.get(appName).put(contextId, newContext);

          return contextId;
       }

       /**
        * Finds the SecurityContext for the application by its id and sets it on the current security context
        * stack.
        *
        * @param    appName
        *           The appserver app name.
        * @param    contextId
        *           The context id.
        *
        * @return   <code>true</code> if the context is successfully changed, <code>false</code> otherwise.
        *
        * @throws   RestrictedUseException
        *           If called from an unexpected caller.
        */
       public boolean setContext(String appName, int contextId)
       throws RestrictedUseException
       {
          // restrict the use of this method
          SecurityUtil.checkCallerAbort(new String[]
          {
             "com.goldencode.p2j.util.appserver.MultiSessionAppserver.switchSession"
          });

          if (!appContextMaps.containsKey(appName) || !appContextMaps.get(appName).containsKey(contextId))
          {
             return false;
          }

          SecurityContext sc = appContextMaps.get(appName).get(contextId);

          // should be called for each task on MSA workers
          SecurityContextStack.setContext(new SecurityContextStack(sc));

          ErrorManager.getErrorHelper().setHeadless(true);
          return true;
       }

       /**
        * Finds the SecurityContext for the application by its id and resets it.
        *
        * @param    appName
        *           The appserver app name.
        * @param    contextId
        *           The context id.
        *
        * @throws   RestrictedUseException
        *           If called from an unexpected caller.
        */
       public void resetContext(String appName, Integer contextId)
       throws RestrictedUseException
       {
          // restrict the use of this method
          SecurityUtil.checkCallerAbort(new String[]
          {
             "com.goldencode.p2j.util.appserver.MultiSessionAppserver.resetSession"
          });

          if (!appContextMaps.containsKey(appName))
          {
             return;
          }

          Map<Integer, SecurityContext> securityContextMap = appContextMaps.get(appName);
          if (!securityContextMap.containsKey(contextId))
          {
             return;
          }

          SecurityContext context = securityContextMap.get(contextId);
          context.reset();
       }

       /**
        * Finds the SecurityContext for the application by its id and deletes it. This method expects to be
        * executed on a thread with the same security context already set.
        *
        * @param    appName
        *           The appserver app name.
        * @param    contextId
        *           The context id.
        *
        * @throws   RestrictedUseException
        *           If called from an unexpected caller.
        */
       public void deleteCurrentContext(String appName, Integer contextId)
       throws RestrictedUseException
       {
          // restrict the use of this method
          SecurityUtil.checkCallerAbort(new String[]
          {
             "com.goldencode.p2j.util.appserver.MultiSessionAppserver.finalizeCurrentContext"
          });

          if (!appContextMaps.containsKey(appName))
          {
             return;
          }

          Map<Integer, SecurityContext> securityContextMap = appContextMaps.get(appName);
          if (!securityContextMap.containsKey(contextId))
          {
             return;
          }

          SecurityContext context = securityContextMap.remove(contextId);
          context.cleanup();
       }

       /**
        * Removes references to the app and deletes all contexts by running the cleanup in threads with
        * the right context in {@link #contextCleanupExecutor} asynchronously.
        *
        * @param    appName
        *           The appserver app name.
        *
        * @throws   RestrictedUseException
        *           If called from an unexpected caller.
        */
       public void removeApp(String appName)
       throws RestrictedUseException
       {
          // restrict the use of this method
          SecurityUtil.checkCallerAbort(new String[]
          {
             "com.goldencode.p2j.util.appserver.MultiSessionAppserver$AgentTerminationTask.run"
          });

          appContextIdCounters.remove(appName);

          Map<Integer, SecurityContext> securityContextMap = appContextMaps.remove(appName);
          if (securityContextMap == null)
          {
             return;
          }

          for (SecurityContext context : securityContextMap.values())
          {
             cleanupContext(context);
          }
       }

       /**
        * Checks if the context for the session exists.
        *
        * @param    appName
        *           The appserver app name.
        * @param    sessionId
        *           The session id.
        *
        * @return   <code>true</code> if the context for the session exists, <code>false</code> otherwise.
        */
       public boolean hasContext(String appName, Integer sessionId)
       {
          if (sessionId == null || !appContextMaps.containsKey(appName))
          {
             return false;
          }
          return appContextMaps.get(appName).containsKey(sessionId);
       }

       /**
        * Deletes the security context async in a thread that is prepared with the right initial context.
        *
        * @param    context
        *           The security context to be deleted.
        */
       private void cleanupContext(SecurityContext context)
       {
          contextCleanupExecutor.execute(() ->
                                         {
                                            SecurityContextStack.setContext(new SecurityContextStack(context));
                                            context.cleanup();
                                         });
       }
    }