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A framework for building RESTful web APIs.
/*
* Copyright 2016 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.api.server.spi.auth;
import com.google.api.client.http.GenericUrl;
import com.google.api.client.http.HttpIOExceptionHandler;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpResponse;
import com.google.api.client.http.HttpUnsuccessfulResponseHandler;
import com.google.api.client.util.Key;
import com.google.api.server.spi.Client;
import com.google.api.server.spi.Constant;
import com.google.api.server.spi.Strings;
import com.google.api.server.spi.request.Attribute;
import com.google.api.server.spi.response.ServiceUnavailableException;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import java.io.IOException;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Pattern;
import javax.servlet.http.HttpServletRequest;
/**
* Common auth utils for built-in authenticators.
*/
public class GoogleAuth {
private static final Logger logger = Logger.getLogger(GoogleAuth.class.getName());
// Identifies JSON Web Tokens
// From java/com/google/gaia/client/AuthSubRequestDetector.java
private static final String BASE64_REGEX = "[a-zA-Z0-9+/=_-]{6,}+";
private static final Pattern JWT_PATTERN =
Pattern.compile(String.format("%s\\.%s\\.%s", BASE64_REGEX, BASE64_REGEX, BASE64_REGEX));
// Remote API for validating OAuth2 access token.
private static final String TOKEN_INFO_ENDPOINT =
"https://www.googleapis.com/oauth2/v2/tokeninfo?access_token=";
@VisibleForTesting
static final String AUTHORIZATION_HEADER = "Authorization";
// See https://tools.ietf.org/html/rfc6750. "Bearer" is the new spec, "OAuth"
// is for backward compatiblity.
@VisibleForTesting
static final String[] ALLOWED_AUTH_SCHEMES = {"Bearer", "OAuth"};
// See https://tools.ietf.org/html/rfc6750. "access_token" is the new spec.
// "bearer_token" is the old name for backward compatibility.
@VisibleForTesting
static final String[] BEARER_TOKEN_PARAMETER_NAMES = {"access_token", "bearer_token"};
@VisibleForTesting
static final String[] OAUTH2_TOKEN_PREFIXES = {"ya29.", "1/"};
@VisibleForTesting
static final List SKIP_CLIENT_ID_CHECK_LIST =
ImmutableList.of(Constant.SKIP_CLIENT_ID_CHECK);
public static String getAuthToken(HttpServletRequest request) {
if (request.getAttribute(Attribute.AUTH_TOKEN) == null) {
String token = getAuthTokenFromHeader(request.getHeader(AUTHORIZATION_HEADER));
if (token == null) {
token = getAuthTokenFromQueryParameters(request);
}
request.setAttribute(Attribute.AUTH_TOKEN, token);
}
return (String) request.getAttribute(Attribute.AUTH_TOKEN);
}
private static String getAuthTokenFromQueryParameters(HttpServletRequest request) {
for (String parameterName : BEARER_TOKEN_PARAMETER_NAMES) {
String token = request.getParameter(parameterName);
if (token != null) {
return token;
}
}
return null;
}
private static String getAuthTokenFromHeader(String authHeader) {
String authScheme = matchAuthScheme(authHeader);
if (authScheme == null || authScheme.length() >= authHeader.length()) {
return null;
} else {
return authHeader.substring(authScheme.length() + 1);
}
}
private static String matchAuthScheme(String authHeader) {
if (authHeader == null) {
return null;
}
for (String authScheme : ALLOWED_AUTH_SCHEMES) {
if (authHeader.startsWith(authScheme)) {
return authScheme;
}
}
return null;
}
static boolean isJwt(String token) {
if (token == null) {
return false;
}
return JWT_PATTERN.matcher(token).matches();
}
static boolean isOAuth2Token(String token) {
if (token == null) {
return false;
}
String strippedToken = token.trim().replaceFirst("^['\"]", "");
for (String prefix : OAUTH2_TOKEN_PREFIXES) {
if (strippedToken.startsWith(prefix)) {
return true;
}
}
return false;
}
/**
* Check if the client id in auth token is whitelisted.
*
* @param clientId clientId
* @param allowedClientIds list of whitelisted clientIds
* @param allowSkipClientIdCheck true only for OAuth2 access token request.
*/
static boolean checkClientId(String clientId, List allowedClientIds,
boolean allowSkipClientIdCheck) {
if (Strings.isWhitelisted(clientId, allowedClientIds)) {
return true;
}
if (allowSkipClientIdCheck && !Strings.isEmptyOrNull(allowedClientIds)
&& allowedClientIds.equals(SKIP_CLIENT_ID_CHECK_LIST)) {
return true;
}
return false;
}
/**
* Check if the audience in auth token is whitelisted. Audience is either equal to the audience
* specified (Android case) or equal to the Client ID field (iOS, general OAuth cases).
*/
static boolean checkAudience(String audience, List allowedAudiences, String clientId) {
if (Strings.isWhitelisted(audience, allowedAudiences)) {
return true;
}
if (!Strings.isEmptyOrWhitespace(audience) && audience.equals(clientId)) {
return true;
}
return false;
}
/**
* Class to hold remote access token validation response.
*/
public static class TokenInfo {
@Key("email") public String email;
@Key("issued_to") public String clientId;
@Key("scope") public String scopes;
@Key("user_id") public String userId;
@Key("error_description") public String errorDescription;
}
/**
* Get OAuth2 token info from remote token validation API.
* Retries IOExceptions and 5xx responses once.
*/
static TokenInfo getTokenInfoRemote(String token) throws ServiceUnavailableException {
try {
HttpRequest request = Client.getInstance().getJsonHttpRequestFactory()
.buildGetRequest(new GenericUrl(TOKEN_INFO_ENDPOINT + token));
configureErrorHandling(request);
return parseTokenInfo(request);
} catch (IOException e) {
throw new ServiceUnavailableException("Failed to perform access token validation", e);
}
}
@VisibleForTesting
static TokenInfo parseTokenInfo(HttpRequest request)
throws IOException, ServiceUnavailableException {
HttpResponse response = request.execute();
int statusCode = response.getStatusCode();
TokenInfo info = response.parseAs(TokenInfo.class);
if (statusCode != 200) {
String errorDescription = "Unknown error";
if (info != null && info.errorDescription != null) {
errorDescription = info.errorDescription;
}
errorDescription += " (" + statusCode + ")";
if (statusCode >= 500) {
logger.log(Level.SEVERE, "Error validating access token: " + errorDescription);
throw new ServiceUnavailableException("Failed to validate access token");
}
logger.log(Level.INFO, "Invalid access token: " + errorDescription);
return null;
}
if (info == null || Strings.isEmptyOrWhitespace(info.email)) {
logger.log(Level.WARNING, "Access token does not contain email scope");
return null;
}
return info;
}
@VisibleForTesting
static void configureErrorHandling(HttpRequest request) {
request.setNumberOfRetries(1)
.setThrowExceptionOnExecuteError(false)
.setIOExceptionHandler(new HttpIOExceptionHandler() {
@Override
public boolean handleIOException(HttpRequest request, boolean supportsRetry) {
return true; // consider all IOException as transient
}
})
.setUnsuccessfulResponseHandler(new HttpUnsuccessfulResponseHandler() {
@Override
public boolean handleResponse(HttpRequest request, HttpResponse response,
boolean supportsRetry) {
return response.getStatusCode() >= 500; // only retry Google's backend errors
}
});
}
}