/*
* Copyright 2011 Google Inc. All Rights Reserved.
*
* 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 com.google.walkaround.wave.server.auth;
import com.google.common.base.Preconditions;
import com.google.inject.Inject;
import com.google.walkaround.util.server.auth.InvalidSecurityTokenException;
import com.google.walkaround.util.server.auth.SecurityTokenHelper;
import com.google.walkaround.util.server.servlet.BadRequestException;
import com.google.walkaround.wave.server.Flag;
import com.google.walkaround.wave.server.FlagName;
import java.util.logging.Logger;
/**
* Utility for creating and verifying XSRF tokens.
*
* @author ohler@google.com (Christian Ohler)
* @author danilatos@google.com (Daniel Danilatos)
*/
public class XsrfHelper {
@SuppressWarnings("unused")
private static final Logger log = Logger.getLogger(XsrfHelper.class.getName());
public static class XsrfTokenExpiredException extends Exception {
private static final long serialVersionUID = 467064784131563198L;
public XsrfTokenExpiredException() {
}
public XsrfTokenExpiredException(String message) {
super(message);
}
public XsrfTokenExpiredException(Throwable cause) {
super(cause);
}
public XsrfTokenExpiredException(String message, Throwable cause) {
super(message, cause);
}
}
private final SecurityTokenHelper helper;
private final long expiryMs;
private final StableUserId userId;
@Inject
public XsrfHelper(SecurityTokenHelper helper,
@Flag(FlagName.XSRF_TOKEN_EXPIRY_SECONDS) int expirySeconds,
StableUserId userId) {
Preconditions.checkArgument(!userId.getId().contains(" "),
"userId contains spaces: %s", userId);
this.helper = helper;
this.expiryMs = expirySeconds * 1000;
this.userId = userId;
}
private String makeHiddenPart(String action) {
return userId.getId() + " " + action;
}
public String createToken(String action) {
long timestamp = System.currentTimeMillis();
return helper.createToken(makeHiddenPart(action), "" + timestamp);
}
/**
* Verifies the token matches the current user and action and has not expired.
*/
public void verify(String action, String token)
throws XsrfTokenExpiredException, InvalidSecurityTokenException {
String visiblePart = helper.verifyAndGetVisiblePart(makeHiddenPart(action), token);
long tokenTime;
try {
tokenTime = Long.parseLong(visiblePart);
} catch (NumberFormatException e) {
throw new BadRequestException(e);
}
if (tokenTime + expiryMs < System.currentTimeMillis()) {
throw new XsrfTokenExpiredException("Token expired: " + action + ", " + userId
+ ", " + token);
}
}
}