//
// SSLManager.h
//
// Library: NetSSL_OpenSSL
// Package: SSLCore
// Module:  SSLManager
//
// Definition of the SSLManager class.
//
// Copyright (c) 2006-2010, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef NetSSL_SSLManager_INCLUDED
#define NetSSL_SSLManager_INCLUDED

#include <unordered_map>

#include <openssl/ssl.h>
#include "Poco/BasicEvent.h"
#include "Poco/Mutex.h"
#include "Poco/Net/CertificateHandlerFactoryMgr.h"
#include "Poco/Net/Context.h"
#include "Poco/Net/InvalidCertificateHandler.h"
#include "Poco/Net/NetSSL.h"
#include "Poco/Net/PrivateKeyFactoryMgr.h"
#include "Poco/Net/VerificationErrorArgs.h"
#include "Poco/SharedPtr.h"
#include "Poco/Util/AbstractConfiguration.h"
#if defined(OPENSSL_FIPS) && OPENSSL_VERSION_NUMBER < 0x010001000L
#    include <openssl/fips.h>
#endif


namespace Poco
{
namespace Net
{


    class Context;


    class NetSSL_API SSLManager
    /// SSLManager is a singleton for holding the default server/client
    /// Context and handling callbacks for certificate verification errors
    /// and private key passphrases.
    ///
    /// Proper initialization of SSLManager is critical.
    ///
    /// SSLManager can be initialized manually, by calling initializeServer()
    /// and/or initializeClient(), or initialization can be automatic. In the latter
    /// case, a Poco::Util::Application instance must be available and the required
    /// configuration properties must be set (see below).
    ///
    /// Note that manual initialization must happen very early in the application,
    /// before defaultClientContext() or defaultServerContext() are called.
    ///
    /// If defaultClientContext() and defaultServerContext() are never called
    /// in an application, initialization of SSLManager can be omitted.
    /// However, in this case, delegates for the ServerVerificationError,
    /// ClientVerificationError and PrivateKeyPassphraseRequired events
    /// must be registered.
    ///
    /// An exemplary documentation which sets either the server or client default context and creates
    /// a PrivateKeyPassphraseHandler that reads the password from the XML file looks like this:
    ///
    ///    <AppConfig>
    ///       <openSSL>
    ///          <server|client>
    ///            <privateKeyFile>mycert.key</privateKeyFile>
    ///            <certificateFile>mycert.crt</certificateFile>
    ///            <caConfig>rootcert.pem</caConfig>
    ///            <verificationMode>none|relaxed|strict|once</verificationMode>
    ///            <verificationDepth>1..9</verificationDepth>
    ///            <loadDefaultCAFile>true|false</loadDefaultCAFile>
    ///            <cipherList>ALL:!ADH:!LOW:!EXP:!MD5:!3DES:@STRENGTH</cipherList>
    ///            <preferServerCiphers>true|false</preferServerCiphers>
    ///            <privateKeyPassphraseHandler>
    ///                <name>KeyFileHandler</name>
    ///                <options>
    ///                    <password>test</password>
    ///                </options>
    ///            </privateKeyPassphraseHandler>
    ///            <invalidCertificateHandler>
    ///                 <name>RejectCertificateHandler</name>
    ///            </invalidCertificateHandler>
    ///            <cacheSessions>true|false</cacheSessions>
    ///            <sessionIdContext>someString</sessionIdContext> <!-- server only -->
    ///            <sessionCacheSize>0..n</sessionCacheSize>       <!-- server only -->
    ///            <sessionTimeout>0..n</sessionTimeout>           <!-- server only -->
    ///            <extendedVerification>true|false</extendedVerification>
    ///            <requireTLSv1>true|false</requireTLSv1>
    ///            <requireTLSv1_1>true|false</requireTLSv1_1>
    ///            <requireTLSv1_2>true|false</requireTLSv1_2>
    ///            <disableProtocols>sslv2,sslv3,tlsv1,tlsv1_1,tlsv1_2</disableProtocols>
    ///            <dhParamsFile>dh.pem</dhParamsFile>
    ///            <ecdhCurve>prime256v1</ecdhCurve>
    ///          </server|client>
    ///          <fips>false</fips>
    ///       </openSSL>
    ///    </AppConfig>
    ///
    /// Following is a list of supported configuration properties. Property names must always
    /// be prefixed with openSSL.server or openSSL.client. Some properties are only supported
    /// for servers.
    ///
    ///    - privateKeyFile (string): The path to the file containing the private key for the certificate
    ///      in PEM format (or containing both the private key and the certificate).
    ///    - certificateFile (string): The Path to the file containing the server's or client's certificate
    ///      in PEM format. Can be omitted if the the file given in privateKeyFile contains the certificate as well.
    ///    - caConfig (string): The path to the file or directory containing the trusted root certificates.
    ///    - verificationMode (string): Specifies whether and how peer certificates are validated (see
    ///      the Context class for details). Valid values are none, relaxed, strict, once.
    ///    - verificationDepth (integer, 1-9): Sets the upper limit for verification chain sizes. Verification
    ///      will fail if a certificate chain larger than this is encountered.
    ///    - loadDefaultCAFile (boolean): Specifies whether the builtin CA certificates from OpenSSL are used.
    ///    - cipherList (string): Specifies the supported ciphers in OpenSSL notation
    ///      (e.g. "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH").
    ///    - preferServerCiphers (bool): When choosing a cipher, use the server's preferences instead of the
    ///      client preferences. When not called, the SSL server will always follow the clients
    ///      preferences. When called, the SSL/TLS server will choose following its own
    ///      preferences.
    ///    - privateKeyPassphraseHandler.name (string): The name of the class (subclass of PrivateKeyPassphraseHandler)
    ///      used for obtaining the passphrase for accessing the private key.
    ///    - privateKeyPassphraseHandler.options.password (string): The password to be used by KeyFileHandler.
    ///    - invalidCertificateHandler.name: The name of the class (subclass of CertificateHandler)
    ///      used for confirming invalid certificates.
    ///    - cacheSessions (boolean): Enables or disables session caching.
    ///    - sessionIdContext (string): contains the application's unique session ID context, which becomes
    ///      part of each session identifier generated by the server. Can be an arbitrary sequence
    ///      of bytes with a maximum length of SSL_MAX_SSL_SESSION_ID_LENGTH. Should be specified
    ///      for a server to enable session caching. Should be specified even if session caching
    ///      is disabled to avoid problems with clients that request session caching (e.g. Firefox 3.6).
    ///      If not specified, defaults to ${application.name}.
    ///    - sessionCacheSize (integer): Sets the maximum size of the server session cache, in number of
    ///      sessions. The default size (according to OpenSSL documentation) is 1024*20, which may be too
    ///      large for many applications, especially on embedded platforms with limited memory.
    ///      Specifying a size of 0 will set an unlimited cache size.
    ///    - sessionTimeout (integer):  Sets the timeout (in seconds) of cached sessions on the server.
    ///    - extendedVerification (boolean): Enable or disable the automatic post-connection
    ///      extended certificate verification.
    ///    - requireTLSv1 (boolean): Require a TLSv1 connection.
    ///    - requireTLSv1_1 (boolean): Require a TLSv1.1 connection.
    ///    - requireTLSv1_2 (boolean): Require a TLSv1.2 connection.
    ///    - disableProtocols (string): A comma-separated list of protocols that should be
    ///      disabled. Valid protocol names are sslv2, sslv3, tlsv1, tlsv1_1, tlsv1_2.
    ///    - dhParamsFile (string): Specifies a file containing Diffie-Hellman parameters.
    ///      If not specified or empty, the default parameters are used.
    ///    - ecdhCurve (string): Specifies the name of the curve to use for ECDH, based
    ///      on the curve names specified in RFC 4492. Defaults to "prime256v1".
    ///    - fips: Enable or disable OpenSSL FIPS mode. Only supported if the OpenSSL version
    ///      that this library is built against supports FIPS mode.
    {
    public:
        typedef Poco::SharedPtr<PrivateKeyPassphraseHandler> PrivateKeyPassphraseHandlerPtr;
        typedef Poco::SharedPtr<InvalidCertificateHandler> InvalidCertificateHandlerPtr;

        Poco::BasicEvent<VerificationErrorArgs> ServerVerificationError;
        /// Fired whenever a certificate verification error is detected by the server during a handshake.

        Poco::BasicEvent<VerificationErrorArgs> ClientVerificationError;
        /// Fired whenever a certificate verification error is detected by the client during a handshake.

        Poco::BasicEvent<std::string> PrivateKeyPassphraseRequired;
        /// Fired when a encrypted certificate is loaded. Not setting the password
        /// in the event parameter will result in a failure to load the certificate.

        static SSLManager & instance();
        /// Returns the instance of the SSLManager singleton.

        void initializeServer(
            PrivateKeyPassphraseHandlerPtr ptrPassphraseHandler,
            InvalidCertificateHandlerPtr ptrCertificateHandler,
            Context::Ptr ptrContext);
        /// Initializes the server side of the SSLManager with a default passphrase handler, a default invalid certificate handler and a default context. If this method
        /// is never called the SSLmanager will try to initialize its members from an application configuration.
        ///
        /// PtrPassphraseHandler and ptrCertificateHandler can be 0. However, in this case, event delegates
        /// must be registered with the ServerVerificationError and PrivateKeyPassphraseRequired events.
        ///
        /// Note: Always create the handlers (or register the corresponding event delegates) before creating
        /// the Context, as during creation of the Context the passphrase for the private key might be needed.
        ///
        /// Valid initialization code would be:
        ///     SharedPtr<PrivateKeyPassphraseHandler> pConsoleHandler = new KeyConsoleHandler;
        ///     SharedPtr<InvalidCertificateHandler> pInvalidCertHandler = new RejectCertificateHandler;
        ///     Context::Ptr pContext = new Context(Context::SERVER_USE, "any.pem", "any.pem", "rootcert.pem", Context::VERIFY_RELAXED, 9, false, "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH");
        ///     SSLManager::instance().initializeServer(pConsoleHandler, pInvalidCertHandler, pContext);

        void initializeClient(
            PrivateKeyPassphraseHandlerPtr ptrPassphraseHandler, InvalidCertificateHandlerPtr ptrHandler, Context::Ptr ptrContext);
        /// Initializes the client side of the SSLManager with a default passphrase handler, a default invalid certificate handler and a default context. If this method
        /// is never called the SSLmanager will try to initialize its members from an application configuration.
        ///
        /// PtrPassphraseHandler and ptrCertificateHandler can be 0. However, in this case, event delegates
        /// must be registered with the ClientVerificationError and PrivateKeyPassphraseRequired events.
        ///
        /// Note: Always create the handlers (or register the corresponding event delegates) before creating
        /// the Context, as during creation of the Context the passphrase for the private key might be needed.
        ///
        /// Valid initialization code would be:
        ///     SharedPtr<PrivateKeyPassphraseHandler> pConsoleHandler = new KeyConsoleHandler;
        ///     SharedPtr<InvalidCertificateHandler> pInvalidCertHandler = new RejectCertificateHandler;
        ///     Context::Ptr pContext = new Context(Context::CLIENT_USE, "", "", "rootcert.pem", Context::VERIFY_RELAXED, 9, false, "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH");
        ///     SSLManager::instance().initializeClient(pConsoleHandler, pInvalidCertHandler, pContext);

        Context::Ptr defaultServerContext();
        /// Returns the default Context used by the server.
        ///
        /// Unless initializeServer() has been called, the first call to this method initializes the default Context
        /// from the application configuration.

        Context::Ptr defaultClientContext();
        /// Returns the default Context used by the client.
        ///
        /// Unless initializeClient() has been called, the first call to this method initializes the default Context
        /// from the application configuration.

        Context::Ptr getCustomServerContext(const std::string & name);
        /// Return custom Context used by the server.

        Context::Ptr setCustomServerContext(const std::string & name, Context::Ptr ctx);
        /// Set custom Context used by the server.
        /// Return pointer on inserted Context or on old Context if exists.

        PrivateKeyPassphraseHandlerPtr serverPassphraseHandler();
        /// Returns the configured passphrase handler of the server. If none is set, the method will create a default one
        /// from an application configuration.

        InvalidCertificateHandlerPtr serverCertificateHandler();
        /// Returns an initialized certificate handler (used by the server to verify client cert) which determines how invalid certificates are treated.
        /// If none is set, it will try to auto-initialize one from an application configuration.

        PrivateKeyPassphraseHandlerPtr clientPassphraseHandler();
        /// Returns the configured passphrase handler of the client. If none is set, the method will create a default one
        /// from an application configuration.

        InvalidCertificateHandlerPtr clientCertificateHandler();
        /// Returns an initialized certificate handler (used by the client to verify server cert) which determines how invalid certificates are treated.
        /// If none is set, it will try to auto-initialize one from an application configuration.

        PrivateKeyFactoryMgr & privateKeyFactoryMgr();
        /// Returns the private key factory manager which stores the
        /// factories for the different registered passphrase handlers for private keys.

        CertificateHandlerFactoryMgr & certificateHandlerFactoryMgr();
        /// Returns the CertificateHandlerFactoryMgr which stores the
        /// factories for the different registered certificate handlers.

        static bool isFIPSEnabled();
        // Returns true if FIPS mode is enabled, false otherwise.

        void shutdown();
        /// Shuts down the SSLManager and releases the default Context
        /// objects. After a call to shutdown(), the SSLManager can no
        /// longer be used.
        ///
        /// Normally, it's not necessary to call this method directly, as this
        /// will be called either by uninitializeSSL(), or when
        /// the SSLManager instance is destroyed.

        static const std::string CFG_SERVER_PREFIX;
        static const std::string CFG_CLIENT_PREFIX;

        static const std::string CFG_PRIV_KEY_FILE;
        static const std::string CFG_CERTIFICATE_FILE;
        static const std::string CFG_CA_LOCATION;
        static const std::string CFG_VER_MODE;
        static const Context::VerificationMode VAL_VER_MODE;
        static const std::string CFG_VER_DEPTH;
        static const int VAL_VER_DEPTH;
        static const std::string CFG_ENABLE_DEFAULT_CA;
        static const bool VAL_ENABLE_DEFAULT_CA;
        static const std::string CFG_CIPHER_LIST;
        static const std::string CFG_CYPHER_LIST; // for backwards compatibility
        static const std::string VAL_CIPHER_LIST;
        static const std::string CFG_PREFER_SERVER_CIPHERS;
        static const std::string CFG_DELEGATE_HANDLER;
        static const std::string VAL_DELEGATE_HANDLER;
        static const std::string CFG_CERTIFICATE_HANDLER;
        static const std::string VAL_CERTIFICATE_HANDLER;
        static const std::string CFG_CACHE_SESSIONS;
        static const std::string CFG_SESSION_ID_CONTEXT;
        static const std::string CFG_SESSION_CACHE_SIZE;
        static const std::string CFG_SESSION_TIMEOUT;
        static const std::string CFG_EXTENDED_VERIFICATION;
        static const std::string CFG_REQUIRE_TLSV1;
        static const std::string CFG_REQUIRE_TLSV1_1;
        static const std::string CFG_REQUIRE_TLSV1_2;
        static const std::string CFG_DISABLE_PROTOCOLS;
        static const std::string CFG_DH_PARAMS_FILE;
        static const std::string CFG_ECDH_CURVE;

#ifdef OPENSSL_FIPS
        static const std::string CFG_FIPS_MODE;
        static const bool VAL_FIPS_MODE;
#endif

    protected:
        static int verifyClientCallback(int ok, X509_STORE_CTX * pStore);
        /// The return value of this method defines how errors in
        /// verification are handled. Return 0 to terminate the handshake,
        /// or 1 to continue despite the error.

        static int verifyServerCallback(int ok, X509_STORE_CTX * pStore);
        /// The return value of this method defines how errors in
        /// verification are handled. Return 0 to terminate the handshake,
        /// or 1 to continue despite the error.

        static int privateKeyPassphraseCallback(char * pBuf, int size, int flag, void * userData);
        /// Method is invoked by OpenSSL to retrieve a passwd for an encrypted certificate.
        /// The request is delegated to the PrivatekeyPassword event. This method returns the
        /// length of the password.

        static Poco::Util::AbstractConfiguration & appConfig();
        /// Returns the application configuration.
        ///
        /// Throws a InvalidStateException if not application instance
        /// is available.

    private:
        SSLManager();
        /// Creates the SSLManager.

        ~SSLManager();
        /// Destroys the SSLManager.

        void initDefaultContext(bool server);
        /// Inits the default context, the first time it is accessed.

        void initEvents(bool server);
        /// Registers delegates at the events according to the configuration.

        void initPassphraseHandler(bool server);
        /// Inits the passphrase handler.

        void initCertificateHandler(bool server);
        /// Inits the certificate handler.

        static int verifyCallback(bool server, int ok, X509_STORE_CTX * pStore);
        /// The return value of this method defines how errors in
        /// verification are handled. Return 0 to terminate the handshake,
        /// or 1 to continue despite the error.

        PrivateKeyFactoryMgr _factoryMgr;
        CertificateHandlerFactoryMgr _certHandlerFactoryMgr;
        Context::Ptr _ptrDefaultServerContext;
        PrivateKeyPassphraseHandlerPtr _ptrServerPassphraseHandler;
        InvalidCertificateHandlerPtr _ptrServerCertificateHandler;
        Context::Ptr _ptrDefaultClientContext;
        PrivateKeyPassphraseHandlerPtr _ptrClientPassphraseHandler;
        InvalidCertificateHandlerPtr _ptrClientCertificateHandler;
        Poco::FastMutex _mutex;

        std::unordered_map<std::string, Context::Ptr> _mapPtrServerContexts;

        friend class Poco::SingletonHolder<SSLManager>;
        friend class Context;
    };


    //
    // inlines
    //
    inline PrivateKeyFactoryMgr & SSLManager::privateKeyFactoryMgr()
    {
        return _factoryMgr;
    }


    inline CertificateHandlerFactoryMgr & SSLManager::certificateHandlerFactoryMgr()
    {
        return _certHandlerFactoryMgr;
    }


    inline bool SSLManager::isFIPSEnabled()
    {
#ifdef OPENSSL_FIPS
        return FIPS_mode() ? true : false;
#else
        return false;
#endif
    }


    inline int SSLManager::verifyServerCallback(int ok, X509_STORE_CTX * pStore)
    {
        return SSLManager::verifyCallback(true, ok, pStore);
    }


    inline int SSLManager::verifyClientCallback(int ok, X509_STORE_CTX * pStore)
    {
        return SSLManager::verifyCallback(false, ok, pStore);
    }


}
} // namespace Poco::Net


#endif // NetSSL_SSLManager_INCLUDED