/*
* Copyright 2011-2012 Amazon.com, Inc. or its affiliates. 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://aws.amazon.com/apache2.0
*
* This file 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.amazonaws.auth;
import com.amazonaws.ClientConfiguration;
import com.amazonaws.services.securitytoken.AWSSecurityTokenService;
import com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClient;
import com.amazonaws.services.securitytoken.model.Credentials;
import com.amazonaws.services.securitytoken.model.GetSessionTokenRequest;
import com.amazonaws.services.securitytoken.model.GetSessionTokenResult;
import java.util.Date;
/**
* AWSCredentialsProvider implementation that uses the AWS Security Token
* Service to create temporary, short-lived sessions to use for authentication.
*/
public class STSSessionCredentialsProvider implements AWSCredentialsProvider {
/** Default duration for started sessions */
public static final int DEFAULT_DURATION_SECONDS = 3600;
/** The client for starting STS sessions */
private final AWSSecurityTokenService securityTokenService;
/** The current session credentials */
private AWSSessionCredentials sessionCredentials;
/** The expiration time for the current session credentials */
private Date sessionCredentialsExpiration;
/**
* Constructs a new STSSessionCredentialsProvider, which will use the
* specified long lived AWS credentials to make a request to the AWS
* Security Token Service (STS) to request short lived session credentials,
* which will then be returned by this class's {@link #getCredentials()}
* method.
*
* @param longLivedCredentials The main AWS credentials for a user's
* account.
*/
public STSSessionCredentialsProvider(AWSCredentials longLivedCredentials) {
this(longLivedCredentials, new ClientConfiguration());
}
/**
* Constructs a new STSSessionCredentialsProvider, which will use the
* specified long lived AWS credentials to make a request to the AWS
* Security Token Service (STS) to request short lived session credentials,
* which will then be returned by this class's {@link #getCredentials()}
* method.
*
* @param longLivedCredentials The main AWS credentials for a user's
* account.
* @param clientConfiguration Client configuration connection parameters.
*/
public STSSessionCredentialsProvider(AWSCredentials longLivedCredentials,
ClientConfiguration clientConfiguration) {
securityTokenService = new AWSSecurityTokenServiceClient(longLivedCredentials,
clientConfiguration);
}
/**
* Constructs a new STSSessionCredentialsProvider, which will use the
* specified credentials provider (which vends long lived AWS credentials)
* to make a request to the AWS Security Token Service (STS) to request
* short lived session credentials, which will then be returned by this
* class's {@link #getCredentials()} method.
*
* @param longLivedCredentialsProvider Credentials provider for the main AWS
* credentials for a user's account.
*/
public STSSessionCredentialsProvider(AWSCredentialsProvider longLivedCredentialsProvider) {
securityTokenService = new AWSSecurityTokenServiceClient(longLivedCredentialsProvider);
}
/**
* Constructs a new STSSessionCredentialsProvider, which will use the
* specified credentials provider (which vends long lived AWS credentials)
* to make a request to the AWS Security Token Service (STS) to request
* short lived session credentials, which will then be returned by this
* class's {@link #getCredentials()} method.
*
* @param longLivedCredentialsProvider Credentials provider for the main AWS
* credentials for a user's account.
* @param clientConfiguration Client configuration connection parameters.
*/
public STSSessionCredentialsProvider(AWSCredentialsProvider longLivedCredentialsProvider,
ClientConfiguration clientConfiguration) {
securityTokenService = new AWSSecurityTokenServiceClient(longLivedCredentialsProvider,
clientConfiguration);
}
/**
* Sets the AWS Security Token Service (STS) endpoint where session
* credentials are retrieved from.
* <p>
* </p>
* The default AWS Security Token Service (STS) endpoint
* ("sts.amazonaws.com") works for all accounts that are not for China
* (Beijing) region or GovCloud. You only need to change the endpoint to
* "sts.cn-north-1.amazonaws.com.cn" when you are requesting session
* credentials for services in China(Beijing) region or
* "sts.us-gov-west-1.amazonaws.com" for GovCloud.
* <p>
* </p>
* Setting this invalidates existing session credentials.
*/
public void setSTSClientEndpoint(String endpoint) {
securityTokenService.setEndpoint(endpoint);
sessionCredentials = null;
}
@Override
public AWSCredentials getCredentials() {
if (needsNewSession())
startSession();
return sessionCredentials;
}
@Override
public void refresh() {
startSession();
}
/**
* Starts a new session by sending a request to the AWS Security Token
* Service (STS) with the long lived AWS credentials. This class then vends
* the short lived session credentials sent back from STS.
*/
private void startSession() {
GetSessionTokenResult sessionTokenResult = securityTokenService
.getSessionToken(new GetSessionTokenRequest()
.withDurationSeconds(DEFAULT_DURATION_SECONDS));
Credentials stsCredentials = sessionTokenResult.getCredentials();
sessionCredentials = new BasicSessionCredentials(
stsCredentials.getAccessKeyId(),
stsCredentials.getSecretAccessKey(),
stsCredentials.getSessionToken());
sessionCredentialsExpiration = stsCredentials.getExpiration();
}
/**
* Returns true if a new STS session needs to be started. A new STS session
* is needed when no session has been started yet, or if the last session is
* within 60 seconds of expiring.
*
* @return True if a new STS session needs to be started.
*/
private boolean needsNewSession() {
if (sessionCredentials == null)
return true;
long timeRemaining = sessionCredentialsExpiration.getTime() - System.currentTimeMillis();
return timeRemaining < (60 * 1000);
}
}