BaseAdminRestHandler.java
/*
** Module : AdminRestHandler.java
** Abstract : Class that handles requests for administration of 4GL resources purposes.
**
** Copyright (c) 2025, Golden Code Development Corporation.
**
** -#- -I- --Date-- ----------------------------------------Description---------------------------------------
** 001 OM 20250310 First revision, extracted common REST code from Tenant/AdminHandler.
*/
/*
** 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
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**
** 0. Attribution Requirement.
**
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*/
package com.goldencode.p2j.admin.server;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.node.*;
import com.goldencode.p2j.admin.*;
import com.goldencode.p2j.main.*;
import com.goldencode.p2j.security.*;
import com.goldencode.p2j.security.SecurityManager;
import com.goldencode.p2j.util.logging.*;
import org.eclipse.jetty.server.*;
import org.eclipse.jetty.server.handler.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.util.logging.*;
import java.util.stream.*;
/**
* Base class for all administration REST handlers.
* <br>
* The derived classes will declare their {@code type} and {@code contextPath} when they are constructed and
* will receive the notifications for processing requests by implementing the four specific methods
* corresponding to HTTP verbs: {@code handleGet()}, {@code handlePut()}, {@code handlePost()}, and
* {@code handleDelete()}.
*/
public abstract class BaseAdminRestHandler
extends AbstractHandler
{
/** Logger */
private static final CentralLogger LOG = CentralLogger.get(BaseAdminRestHandler.class);
/** The URL path it will handle.*/
protected final String contextPath;
/** The handler used for authentication and authorization. */
protected final WebAuthHandler authenticationHandler;
/** Instance used for executing requests in a context. */
protected final LegacyWebSecurityManager wsm;
/** Used to parse the HTTP body as a JSON object. */
protected final ThreadLocal<ObjectMapper> mapper = ThreadLocal.withInitial(ObjectMapper::new);
/**
* Constructs a new handler for administration of some resource using REST APIs.
*
* @param contextPath
* The URL path it will handle.
* @param authenticationHandler
* The WebAuthHandler used for authorisation.
*/
protected BaseAdminRestHandler(String contextPath, WebAuthHandler authenticationHandler)
{
this.wsm = SecurityManager.getInstance().legacyWebSm;
this.authenticationHandler = authenticationHandler;
this.contextPath = contextPath;
}
/**
* Method for handling the requests. Will perform checking, authentication and authorization before
* dispatching the execution to proper method/verb.
*
* @param target
* The target of the request - either a URI or a name.
* @param baseRequest
* The original unwrapped request object.
* @param request
* The request either as the {@link Request} object or a wrapper of that request.
* @param response
* The response as the {@link Response} object or a wrapper of that request.
*/
@Override
public void handle(String target,
Request baseRequest,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException
{
// quick validation
if (baseRequest.isHandled()) // already handled by other handler?
{
return;
}
if (target == null) // should not be possible
{
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
return;
}
else if (!target.startsWith(contextPath))
{
return; // not my business
}
baseRequest.setHandled(true);
response.setContentType("application/json");
// check authorization:
String token = authenticationHandler.authorize(target, request, response);
if (token == null)
{
response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
return;
}
String body = request.getReader().lines().collect(Collectors.joining());
target = trimContextPrefix(target);
switch (baseRequest.getMethod())
{
case "GET":
handleGet(target, body, response, token);
break;
case "POST":
handlePost(target, body, response, token);
break;
case "PUT":
handlePut(target, body, response, token);
break;
case "DELETE":
handleDelete(target, body, response, token);
break;
default:
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
}
/**
* Implement this method for handling the GET requests. The result should be written directly to
* {@code response}'s writer. The default implementation will simply return error 400 / Bad request.
*
* @param target
* The relative target of the request. From the absolute URL, the context prefix was eliminated.
* @param body
* The payload of the request (optional).
* @param response
* The response as the {@link Response} object or a wrapper of that request.
* @param token
* The authentication token.
*/
protected void handleGet(String target, String body, HttpServletResponse response, String token)
{
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
/**
* Implement this method for handling the POST requests. The result should be written directly to
* {@code response}'s writer. The default implementation will simply return error 400 / Bad request.
*
* @param target
* The relative target of the request. From the absolute URL, the context prefix was eliminated.
* @param body
* The payload of the request (optional).
* @param response
* The response as the {@link Response} object or a wrapper of that request.
* @param token
* The authentication token.
*/
protected void handlePost(String target, String body, HttpServletResponse response, String token)
{
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
/**
* Implement this method for handling the PUT requests. The result should be written directly to
* {@code response}'s writer. The default implementation will simply return error 400 / Bad request.
*
* @param target
* The relative target of the request. From the absolute URL, the context prefix was eliminated.
* @param body
* The payload of the request (optional).
* @param response
* The response as the {@link Response} object or a wrapper of that request.
* @param token
* The authentication token.
*/
protected void handlePut(String target, String body, HttpServletResponse response, String token)
{
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
/**
* Implement this method for handling the DELETE requests. The result should be written directly to
* {@code response}'s writer. The default implementation will simply return error 400 / Bad request.
*
* @param target
* The relative target of the request. From the absolute URL, the context prefix was eliminated.
* @param body
* The payload of the request (optional).
* @param response
* The response as the {@link Response} object or a wrapper of that request.
* @param token
* The authentication token.
*/
protected void handleDelete(String target, String body, HttpServletResponse response, String token)
{
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
/**
* Execute the specified task in the context associated with the web request identified via the specified
* authentication token.
*
* @param token
* The authentication token.
* @param task
* The task to be performed.
*/
protected final void executeInContext(String token, Runnable task)
{
wsm.executeInContext(token, () -> {
AdminServerImpl.setTargetLive(true, false, true);
task.run();
}, true);
}
/**
* Execute the given task and assign a message to the HTTP response.
*
* @param token
* The token used in the request.
* @param response
* The HTTP response.
* @param task
* The task to be executed.
* @param result
* The field that will contain the result after the execution is performed.
* @param errorSink
* A sink for errors encountered.
*
* @return {@code true} if the operations finish successfully, {@code false} otherwise.
*/
protected final boolean executeAndWriteResponse(String token,
HttpServletResponse response,
Runnable task,
Boolean[] result,
List<String> errorSink)
{
return executeAndWriteResponse(token, response, task, "success", result, errorSink);
}
/**
* Execute the given task and assign a message to the HTTP response.
*
* @param token
* The token used in the request.
* @param response
* The HTTP response.
* @param task
* The task to be executed.
* @param message
* The key value that will be written in the JSON response.
* @param result
* The field that will contain the result after the execution is performed.
* @param errorSink
* A sink for errors encountered.
*
* @return {@code true} if the operations finish successfully, {@code false} otherwise.
*/
protected final boolean executeAndWriteResponse(String token,
HttpServletResponse response,
Runnable task,
String message,
Boolean[] result,
List<String> errorSink)
{
wsm.executeInContext(token, task, true);
try
{
if (errorSink.isEmpty())
{
response.getWriter().write("{\n \"" + message + "\": " + result[0] + " \n}");
return true;
}
ObjectMapper objectMapper = mapper.get();
ObjectNode outerNode = objectMapper.createObjectNode();
outerNode.put(message, result[0]);
ArrayNode errorArray = objectMapper.createArrayNode();
for (String errMsg : errorSink)
{
errorArray.add(errMsg);
}
outerNode.set("errors", errorArray);
response.getWriter().write(outerNode.toString());
return true;
}
catch (IOException e)
{
LOG.log(Level.WARNING, "Could not write response due to " + e.getMessage());
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
return false;
}
}
/**
* Cleaning up the target by removing the context path. This information is not useful since all requests
* dispatched to this handler are filtered to match this prefix.
*/
private String trimContextPrefix(String originalTarget)
{
if (!originalTarget.startsWith(contextPath))
{
LOG.warning(
"Invalid context received '" + originalTarget + "'. Was expecting '" + contextPath + "'.");
return originalTarget;
}
String newTarget = originalTarget.substring(contextPath.length());
// drop the starting "/" if any:
if (newTarget.startsWith("/"))
{
newTarget = newTarget.substring(1);
}
return newTarget;
}
/**
* Parse a JSON and extract the value (String, int or boolean for the moment) of a given field.
*
* @param body
* The JSON data.
* @param fieldName
* The field for which the value is extracted.
* @param cls
* The expected type of value that is retrieved.
*
* @return The value of the given field.
*/
protected Object extractFirstLevelValue(String body, String fieldName, Class<?> cls)
{
try
{
JsonNode rootNode = mapper.get().readTree(body);
if (rootNode.has(fieldName))
{
if (cls == String.class)
{
return rootNode.get(fieldName).asText();
}
else if (cls == boolean.class || cls == Boolean.class)
{
return rootNode.get(fieldName).asBoolean();
}
else if (cls == int.class || cls == Integer.class)
{
return rootNode.get(fieldName).asInt();
}
}
}
catch (JsonProcessingException e)
{
LOG.log(Level.WARNING, "Unable to parse JSON due to " + e.getMessage());
}
return null;
}
}