/**
 * Licensed to the University Corporation for Advanced Internet
 * Development, Inc. (UCAID) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.
 *
 * UCAID licenses this file to you 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.
 */

/**
 * @file xmltooling/security/AbstractPKIXTrustEngine.h
 * 
 * A trust engine that uses X.509 trust anchors and CRLs associated with a peer
 * to perform PKIX validation of signatures and credentials.
 */

#if !defined(__xmltooling_pkixtrust_h__) && !defined(XMLTOOLING_NO_XMLSEC)
#define __xmltooling_pkixtrust_h__

#include <xmltooling/security/OpenSSLTrustEngine.h>
#include <xmltooling/security/SignatureTrustEngine.h>

#include <set>
#include <string>
#include <boost/ptr_container/ptr_vector.hpp>

namespace xmltooling {

    class XMLTOOL_API OpenSSLPathValidator;
    class XMLTOOL_API XSECCryptoX509CRL;

    /**
     * A trust engine that uses X.509 trust anchors and CRLs associated with a peer
     * to perform PKIX validation of signatures and credentials.
     */
    class XMLTOOL_API AbstractPKIXTrustEngine : public SignatureTrustEngine, public OpenSSLTrustEngine
    {
    protected:
        /**
         * Constructor.
         * 
         * If a DOM is supplied, the following XML content is supported:
         * 
         * <ul>
         *  <li>checkRevocation attribute (off, entityOnly, fullChain)
         *  <li>policyMappingInhibit attribute (boolean)
         *  <li>anyPolicyInhibit attribute (boolean)
         *  <li>&t;PathValidator&gt; element (zero or more)
         *  <li>&lt;TrustedName&gt; element (zero or more)
         *  <li>&lt;PolicyOID&gt; element (zero or more)
         * </ul>
         * 
         * @param e DOM to supply configuration for provider
         */
        AbstractPKIXTrustEngine(const xercesc::DOMElement* e=nullptr);

        /** Plugins used to perform path validation. */
        boost::ptr_vector<OpenSSLPathValidator> m_pathValidators;

        /** Controls revocation checking, currently limited to CRLs and supports "off", "entityOnly", "fullChain". */
        std::string m_checkRevocation;

        /** Deprecated option, equivalent to checkRevocation="fullChain". */
        bool m_fullCRLChain;

        /** Disable policy mapping when applying PKIX policy checking. */
        bool m_policyMappingInhibit;

        /** Disallow the anyPolicy OID (2.5.29.32.0) when applying PKIX policy checking. */
        bool m_anyPolicyInhibit;

        /** A list of acceptable policy OIDs (explicit policy checking). */
        std::set<std::string> m_policyOIDs;

        /** A list of trusted names (subject DNs / CN attributes / subjectAltName entries). */
        std::set<std::string> m_trustedNames;

        /**
         * Checks that either the name of the peer with the given credentials or the names
         * of the credentials match the subject or subject alternate names of the certificate.
         * Alternatively explicit trusted names can be supplied statically via configuration.
         * 
         * @param certEE        the credential for the entity to validate
         * @param credResolver  source of trusted credentials
         * @param criteria      criteria for selecting credentials, including the peer name
         * 
         * @return true the name check succeeds, false if not
         */
        bool checkEntityNames(X509* certEE, const CredentialResolver& credResolver, const CredentialCriteria& criteria) const;

    public:
        virtual ~AbstractPKIXTrustEngine();

        bool validate(
            xmlsignature::Signature& sig,
            const CredentialResolver& credResolver,
            CredentialCriteria* criteria=nullptr
            ) const;

        bool validate(
            const XMLCh* sigAlgorithm,
            const char* sig,
            xmlsignature::KeyInfo* keyInfo,
            const char* in,
            unsigned int in_len,
            const CredentialResolver& credResolver,
            CredentialCriteria* criteria=nullptr
            ) const;

        bool validate(
            XSECCryptoX509* certEE,
            const std::vector<XSECCryptoX509*>& certChain,
            const CredentialResolver& credResolver,
            CredentialCriteria* criteria=nullptr
            ) const;

        bool validate(
            X509* certEE,
            STACK_OF(X509)* certChain,
            const CredentialResolver& credResolver,
            CredentialCriteria* criteria=nullptr
            ) const;

        /**
         * Stateful interface that supplies PKIX validation data to the trust engine.
         * Applications can adapt this TrustEngine to their environment by returning
         * implementations of this interface from the getPKIXValidationInfoIterator
         * method.
         */
        class XMLTOOL_API PKIXValidationInfoIterator {
            MAKE_NONCOPYABLE(PKIXValidationInfoIterator);
        protected:
            PKIXValidationInfoIterator();
            
        public:
            virtual ~PKIXValidationInfoIterator();
            
            /**
             * Advances to the next set of information, if any.
             * 
             * @return true iff another set of information is available
             */
            virtual bool next()=0;
            
            /**
             * Returns the allowable trust chain verification depth for the
             * validation data in the current position.
             * 
             * @return  allowable trust chain verification depth
             */
            virtual int getVerificationDepth() const=0;
            
            /**
             * Returns the set of trust anchors for the validation data in the
             * current position. Keeping the certificates beyond the lifetime
             * of the iterator or after advancing to the next position requires
             * copying them.
             * 
             * @return  set of trust anchors
             */
            virtual const std::vector<XSECCryptoX509*>& getTrustAnchors() const=0;

            /**
             * Returns the set of CRLs for the validation data in the
             * current position. Keeping the CRLs beyond the lifetime
             * of the iterator or after advancing to the next position requires
             * copying them.
             * 
             * @return  set of CRLs
             */
            virtual const std::vector<XSECCryptoX509CRL*>& getCRLs() const=0;
        };
        
        /**
         * Provides access to the information necessary, for the given credential source, for
         * PKIX validation of credentials. Each set of validation information returned
         * will be tried, in turn, until one succeeds or no more remain.
         * The caller must free the returned interface when finished with it.
         * 
         * @param pkixSource        the peer for which validation rules are required
         * @param criteria          criteria for selecting validation rules
         * @return interface for obtaining validation data
         */
        virtual PKIXValidationInfoIterator* getPKIXValidationInfoIterator(
            const CredentialResolver& pkixSource, CredentialCriteria* criteria=nullptr
            ) const=0;

    private:
        bool validateWithCRLs(
            X509* certEE,
            STACK_OF(X509)* certChain,
            const CredentialResolver& credResolver,
            CredentialCriteria* criteria=nullptr,
            const std::vector<XSECCryptoX509CRL*>* inlineCRLs=nullptr
            ) const;

        friend class XMLTOOL_DLLLOCAL PKIXParams;
    };
};

#endif /* __xmltooling_pkixtrust_h__ */