SAML2ArtifactType0004Builder.java

/*
 * Copyright [2006] [University Corporation for Advanced Internet Development, 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.opensaml.saml2.binding.artifact;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import org.opensaml.common.SAMLObject;
import org.opensaml.common.binding.BasicEndpointSelector;
import org.opensaml.common.binding.SAMLMessageContext;
import org.opensaml.common.xml.SAMLConstants;
import org.opensaml.saml2.core.NameID;
import org.opensaml.saml2.metadata.ArtifactResolutionService;
import org.opensaml.saml2.metadata.Endpoint;
import org.opensaml.saml2.metadata.IndexedEndpoint;
import org.opensaml.xml.util.DatatypeHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * SAML 2, type 0x0004, artifact builder.
 */
public class SAML2ArtifactType0004Builder implements SAML2ArtifactBuilder<SAML2ArtifactType0004> {

    /** Class logger. */
    private final Logger log = LoggerFactory.getLogger(SAML2ArtifactType0004Builder.class);

    /** {@inheritDoc} */
    public SAML2ArtifactType0004 buildArtifact(byte[] artifact) {
        return SAML2ArtifactType0004.parseArtifact(artifact);
    }

    /** {@inheritDoc} */
    public SAML2ArtifactType0004 buildArtifact(SAMLMessageContext<SAMLObject, SAMLObject, NameID> requestContext) {
        try {
            IndexedEndpoint acsEndpoint = (IndexedEndpoint) getAcsEndpoint(requestContext);
            byte[] endpointIndex = DatatypeHelper.intToByteArray(acsEndpoint.getIndex());
            byte[] trimmedIndex = new byte[2];
            trimmedIndex[0] = endpointIndex[2];
            trimmedIndex[1] = endpointIndex[3];

            MessageDigest sha1Digester = MessageDigest.getInstance("SHA-1");
            byte[] source = sha1Digester.digest(requestContext.getLocalEntityId().getBytes());

            SecureRandom handleGenerator = SecureRandom.getInstance("SHA1PRNG");
            byte[] assertionHandle;
            assertionHandle = new byte[20];
            handleGenerator.nextBytes(assertionHandle);

            return new SAML2ArtifactType0004(trimmedIndex, source, assertionHandle);
        } catch (NoSuchAlgorithmException e) {
            log.error("JVM does not support required cryptography algorithms: SHA-1/SHA1PRNG.", e);
            throw new InternalError("JVM does not support required cryptography algorithms: SHA-1/SHA1PRNG.");
        }
    }

    /**
     * Gets the source location used to for the artifacts created by this encoder.
     * 
     * @param requestContext current request context
     * 
     * @return source location used to for the artifacts created by this encoder
     */
    protected Endpoint getAcsEndpoint(SAMLMessageContext<SAMLObject, SAMLObject, NameID> requestContext) {
        BasicEndpointSelector selector = new BasicEndpointSelector();
        selector.setEndpointType(ArtifactResolutionService.DEFAULT_ELEMENT_NAME);
        selector.getSupportedIssuerBindings().add(SAMLConstants.SAML2_SOAP11_BINDING_URI);
        selector.setMetadataProvider(requestContext.getMetadataProvider());
        selector.setEntityMetadata(requestContext.getLocalEntityMetadata());
        selector.setEntityRoleMetadata(requestContext.getLocalEntityRoleMetadata());

        Endpoint acsEndpoint = selector.selectEndpoint();

        if (acsEndpoint == null) {
            log.error("Unable to select source location for artifact.  No artifact resolution service defined for issuer.");
            return null;
        }

        return acsEndpoint;
    }
}