/*
* Copyright (c) 2013 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License. You may obtain
* a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package org.drivemarks.web;
import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson.JacksonFactory;
import com.google.api.services.oauth2.Oauth2;
import com.google.api.services.oauth2.model.Userinfo;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import java.io.IOException;
import java.io.InputStream;
import java.io.Writer;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.drivemarks.web.models.State;
/**
* Abstract servlet that sets up credentials and provides some convenience
* methods.
* @author jbd@google.com (Burcu Dogan)
*/
@SuppressWarnings("serial")
public abstract class BaseServlet extends HttpServlet {
protected static final HttpTransport TRANSPORT = new NetHttpTransport();
protected static final JsonFactory JSON_FACTORY = new JacksonFactory();
protected static GoogleClientSecrets googleClientSecrets;
protected CredentialManager credentialManager;
protected Configuration fileMarkerCfg;
/**
* Initializes the servlet.
*/
@Override
public void init() throws ServletException {
super.init();
// init credential manager
credentialManager = new CredentialManager(
getClientSecrets(), TRANSPORT, JSON_FACTORY);
fileMarkerCfg = new Configuration();//create a FreeMarker configuration object
fileMarkerCfg.setServletContextForTemplateLoading(getServletContext(),
"WEB-INF/templates");
fileMarkerCfg.setDefaultEncoding("utf-8");
}
/**
* Redirects to OAuth2 consent page if user is not logged in.
* @param req Request object.
* @param resp Response object.
* @throws IOException
*/
protected void loginIfRequired(HttpServletRequest req,
HttpServletResponse resp, GoogleJsonResponseException e) throws IOException {
if (e.getStatusCode() == 401 || e.getStatusCode() == 403) {
StringBuffer requestURL = req.getRequestURL();
if (req.getQueryString() != null) {
requestURL.append("?").append(req.getQueryString());
}
req.getSession().setAttribute(KEY_SESSION_REDIRECT, requestURL.toString());
resp.sendRedirect("/login");
}
}
/**
* If OAuth2 redirect callback is invoked and there is a code query param,
* retrieve user credentials and profile. Then, redirect to the home page.
* @param req Request object.
* @param resp Response object.
* @throws IOException
*/
protected boolean handleCallbackIfRequired(HttpServletRequest req,
HttpServletResponse resp) throws IOException {
String code = req.getParameter("code");
if (code != null) {
// retrieve new credentials with code
Credential credential = credentialManager.retrieve(code);
// request userinfo
Oauth2 service = getOauth2Service(credential);
Userinfo about = service.userinfo().get().execute();
String id = about.getId();
credentialManager.save(id, credential);
req.getSession().setAttribute(KEY_SESSION_USERID, id);
String redirect = (String) req.getSession().getAttribute(KEY_SESSION_REDIRECT);
req.getSession().setAttribute(KEY_SESSION_REDIRECT, null);
if (redirect != null) {
resp.sendRedirect(redirect);
} else {
resp.sendRedirect("?");
}
return true;
}
return false;
}
/**
* Returns the credentials of the user in the session. If user is not in the
* session, returns null.
* @param req Request object.
* @param resp Response object.
* @return Credential object of the user in session or null.
*/
protected Credential getCredential(HttpServletRequest req,
HttpServletResponse resp) {
String userId = (String) req.getSession().getAttribute(KEY_SESSION_USERID);
if (userId != null) {
return credentialManager.get(userId);
}
return null;
}
/**
* Deletes the credentials of the user in the session permanently and removes
* the user from the session.
* @param req Request object.
* @param resp Response object.
*/
protected void deleteCredential(HttpServletRequest req,
HttpServletResponse resp) {
String userId = (String) req.getSession().getAttribute(KEY_SESSION_USERID);
if (userId != null) {
credentialManager.delete(userId);
req.getSession().removeAttribute(KEY_SESSION_USERID);
}
}
/**
* Build and return an Oauth2 service object based on given request parameters.
* @param credential User credentials.
* @return Drive service object that is ready to make requests, or null if
* there was a problem.
*/
protected Oauth2 getOauth2Service(Credential credential) {
return new Oauth2.Builder(TRANSPORT, JSON_FACTORY, credential).build();
}
/**
* Returns true if one of the required query parameters is missing.
* @param req
* @param resp
* @param paramNames
* @return
* @throws IOException
*/
protected boolean requireQueryParams(HttpServletRequest req,
HttpServletResponse resp, String... paramNames) throws IOException {
for (String paramName: paramNames) {
if (req.getParameter(paramName) == null) {
resp.sendError(400, "Missing parameter: " + paramName);
return true;
}
}
return false;
}
/**
* Renders a template.
* @param resp
* @param templateName
* @param root
* @throws IOException
*/
protected void render(
HttpServletResponse resp, String templateName, Map<String, Object> root)
throws IOException {
Template t = fileMarkerCfg.getTemplate(templateName);
resp.setContentType("text/html; charset=utf-8");
Writer out = resp.getWriter();
try {
t.process(root, out);
} catch (TemplateException e) {
throw new RuntimeException(e);
}
}
/**
* Gets the state from request parameters.
* @param req
* @return The {@code State} object serialized from the
* query parameter `state`.
*/
protected State getState(HttpServletRequest req) {
if (req.getParameter("state") != null) {
return new State(req.getParameter("state"));
}
return null;
}
/**
* Reads client_secrets.json and creates a GoogleClientSecrets object.
* @return A GoogleClientsSecrets object.
*/
private GoogleClientSecrets getClientSecrets() {
if (googleClientSecrets == null) {
InputStream stream =
getServletContext().getResourceAsStream(CLIENT_SECRETS_FILE_PATH);
try {
googleClientSecrets = GoogleClientSecrets.load(JSON_FACTORY, stream);
} catch (IOException e) {
throw new RuntimeException("No client_secrets.json found");
}
}
return googleClientSecrets;
}
public static final String KEY_SESSION_USERID = "user_id";
public static final String KEY_SESSION_REDIRECT = "redirect";
public static final String DEFAULT_MIMETYPE = "text/plain";
public static final String CLIENT_SECRETS_FILE_PATH
= "/WEB-INF/client_secrets.json";
}