/*    Copyright 2009 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects
 *    for all of the code used other than as permitted herein. If you modify
 *    file(s) with this exception, you may extend this exception to your
 *    version of the file(s), but you are not obligated to do so. If you do not
 *    wish to do so, delete this exception statement from your version. If you
 *    delete this exception statement from all source files in the program,
 *    then also delete it in the license file.
 */

#pragma once

#include <boost/optional.hpp>
#include <memory>
#include <string>

#include "mongo/config.h"

#ifdef MONGO_CONFIG_SSL

#include "mongo/base/disallow_copying.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/db/service_context.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/util/decorable.h"
#include "mongo/util/net/sock.h"
#include "mongo/util/net/ssl/apple.hpp"
#include "mongo/util/net/ssl_types.h"
#include "mongo/util/time_support.h"

// SChannel implementation
#if MONGO_CONFIG_SSL_PROVIDER == MONGO_CONFIG_SSL_PROVIDER_OPENSSL
#include <openssl/err.h>
#include <openssl/ssl.h>
#endif
#endif  // #ifdef MONGO_CONFIG_SSL

namespace mongo {
/*
 * @return the SSL version std::string prefixed with prefix and suffixed with suffix
 */
const std::string getSSLVersion(const std::string& prefix, const std::string& suffix);
}

#ifdef MONGO_CONFIG_SSL
namespace mongo {
struct SSLParams;

#if MONGO_CONFIG_SSL_PROVIDER == MONGO_CONFIG_SSL_PROVIDER_OPENSSL
typedef SSL_CTX* SSLContextType;
typedef SSL* SSLConnectionType;
#elif MONGO_CONFIG_SSL_PROVIDER == MONGO_CONFIG_SSL_PROVIDER_WINDOWS
typedef SCHANNEL_CRED* SSLContextType;
typedef PCtxtHandle SSLConnectionType;
#elif MONGO_CONFIG_SSL_PROVIDER == MONGO_CONFIG_SSL_PROVIDER_APPLE
typedef asio::ssl::apple::Context* SSLContextType;
typedef SSLContextRef SSLConnectionType;
#else
#error "Unknown SSL Provider"
#endif

/**
 * Maintain per connection SSL state for the Sock class. Used by SSLManagerInterface to perform SSL
 * operations.
 */
class SSLConnectionInterface {
public:
    virtual ~SSLConnectionInterface();

    virtual std::string getSNIServerName() const = 0;
};

struct SSLConfiguration {
    bool isClusterMember(StringData subjectName) const;
    bool isClusterMember(const SSLX509Name& subjectName) const;
    BSONObj getServerStatusBSON() const;
    SSLX509Name serverSubjectName;
    SSLX509Name clientSubjectName;
    Date_t serverCertificateExpirationDate;
    bool hasCA = false;
};

/**
 * Stores information about a globally unique OID.
 */
class ASN1OID {
public:
    ASN1OID(std::string identifier, std::string shortDescription, std::string longDescription)
        : identifier(std::move(identifier)),
          shortDescription(std::move(shortDescription)),
          longDescription(std::move(longDescription)) {}

    std::string identifier;        // An OID
    std::string shortDescription;  // A brief description of the entity associated with the OID
    std::string longDescription;   // A long form description of the entity associated with the OID
};
const ASN1OID mongodbRolesOID("1.3.6.1.4.1.34601.2.1.1",
                              "MongoRoles",
                              "Sequence of MongoDB Database Roles");

/**
 * Counts of negogtiated version used by TLS connections.
 */
struct TLSVersionCounts {
    AtomicInt64 tls10;
    AtomicInt64 tls11;
    AtomicInt64 tls12;

    static TLSVersionCounts& get(ServiceContext* serviceContext);
};

class SSLManagerInterface : public Decorable<SSLManagerInterface> {
public:
    static std::unique_ptr<SSLManagerInterface> create(const SSLParams& params, bool isServer);

    virtual ~SSLManagerInterface();

    /**
     * Initiates a TLS connection.
     * Throws SocketException on failure.
     * @return a pointer to an SSLConnectionInterface. Resources are freed in
     * SSLConnectionInterface's destructor
     */
    virtual SSLConnectionInterface* connect(Socket* socket) = 0;

    /**
     * Waits for the other side to initiate a TLS connection.
     * Throws SocketException on failure.
     * @return a pointer to an SSLConnectionInterface. Resources are freed in
     * SSLConnectionInterface's destructor
     */
    virtual SSLConnectionInterface* accept(Socket* socket, const char* initialBytes, int len) = 0;

    /**
     * Fetches a peer certificate and validates it if it exists
     * Throws NetworkException on failure
     * @return a std::string containing the certificate's subject name.
     *
     * This version of parseAndValidatePeerCertificate is deprecated because it throws a
     * NetworkException upon failure. New code should prefer the version that returns
     * a StatusWith instead.
     */
    virtual SSLPeerInfo parseAndValidatePeerCertificateDeprecated(
        const SSLConnectionInterface* conn, const std::string& remoteHost) = 0;

    /**
     * Gets the SSLConfiguration containing all information about the current SSL setup
     * @return the SSLConfiguration
     */
    virtual const SSLConfiguration& getSSLConfiguration() const = 0;

    /**
    * Fetches the error text for an error code, in a thread-safe manner.
    */
    static std::string getSSLErrorMessage(int code);

    /**
     * SSL wrappers
     */
    virtual int SSL_read(SSLConnectionInterface* conn, void* buf, int num) = 0;

    virtual int SSL_write(SSLConnectionInterface* conn, const void* buf, int num) = 0;

    virtual int SSL_shutdown(SSLConnectionInterface* conn) = 0;

    enum class ConnectionDirection { kIncoming, kOutgoing };

    /**
     * Initializes an OpenSSL context according to the provided settings. Only settings which are
     * acceptable on non-blocking connections are set. "direction" specifies whether the SSL_CTX
     * will be used to make outgoing connections or accept incoming connections.
     */
    virtual Status initSSLContext(SSLContextType context,
                                  const SSLParams& params,
                                  ConnectionDirection direction) = 0;

    /**
     * Fetches a peer certificate and validates it if it exists. If validation fails, but weak
     * validation is enabled, boost::none will be returned. If validation fails, and invalid
     * certificates are not allowed, a non-OK status will be returned. If validation is successful,
     * an engaged optional containing the certificate's subject name, and any roles acquired by
     * X509 authorization will be returned.
     */
    virtual StatusWith<boost::optional<SSLPeerInfo>> parseAndValidatePeerCertificate(
        SSLConnectionType ssl, const std::string& remoteHost) = 0;
};

// Access SSL functions through this instance.
SSLManagerInterface* getSSLManager();

extern bool isSSLServer;

/**
 * Returns true if the `nameToMatch` is a valid match against the `certHostName` requirement from an
 * x.509 certificate.  Matches a remote host name to an x.509 host name, including wildcards.
 */
bool hostNameMatchForX509Certificates(std::string nameToMatch, std::string certHostName);

/**
 * Parse a binary blob of DER encoded ASN.1 into a set of RoleNames.
 */
StatusWith<stdx::unordered_set<RoleName>> parsePeerRoles(ConstDataRange cdrExtension);

/**
 * Strip the trailing '.' in FQDN.
 */
std::string removeFQDNRoot(std::string name);

/**
 * Escape a string per RGC 2253
 *
 * See "2.4 Converting an AttributeValue from ASN.1 to a String" in RFC 2243
 */
std::string escapeRfc2253(StringData str);

}  // namespace mongo
#endif  // #ifdef MONGO_CONFIG_SSL