<?php
/* Icinga Web 2 | (c) 2015 Icinga Development Team | GPLv2+ */

namespace Icinga\Protocol\Ldap;

use Icinga\Application\Logger;
use stdClass;

/**
 * The properties and capabilities of an LDAP server
 *
 * Provides information about the available encryption mechanisms (StartTLS), the supported
 * LDAP protocol (v2/v3), vendor-specific extensions or protocols controls and extensions.
 */
class LdapCapabilities
{
    const LDAP_SERVER_START_TLS_OID = '1.3.6.1.4.1.1466.20037';

    const LDAP_PAGED_RESULT_OID_STRING = '1.2.840.113556.1.4.319';

    const LDAP_SERVER_SHOW_DELETED_OID = '1.2.840.113556.1.4.417';

    const LDAP_SERVER_SORT_OID = '1.2.840.113556.1.4.473';

    const LDAP_SERVER_CROSSDOM_MOVE_TARGET_OID = '1.2.840.113556.1.4.521';

    const LDAP_SERVER_NOTIFICATION_OID = '1.2.840.113556.1.4.528';

    const LDAP_SERVER_EXTENDED_DN_OID = '1.2.840.113556.1.4.529';

    const LDAP_SERVER_LAZY_COMMIT_OID = '1.2.840.113556.1.4.619';

    const LDAP_SERVER_SD_FLAGS_OID = '1.2.840.113556.1.4.801';

    const LDAP_SERVER_TREE_DELETE_OID = '1.2.840.113556.1.4.805';

    const LDAP_SERVER_DIRSYNC_OID = '1.2.840.113556.1.4.841';

    const LDAP_SERVER_VERIFY_NAME_OID = '1.2.840.113556.1.4.1338';

    const LDAP_SERVER_DOMAIN_SCOPE_OID = '1.2.840.113556.1.4.1339';

    const LDAP_SERVER_SEARCH_OPTIONS_OID = '1.2.840.113556.1.4.1340';

    const LDAP_SERVER_PERMISSIVE_MODIFY_OID = '1.2.840.113556.1.4.1413';

    const LDAP_SERVER_ASQ_OID = '1.2.840.113556.1.4.1504';

    const LDAP_SERVER_FAST_BIND_OID = '1.2.840.113556.1.4.1781';

    const LDAP_CONTROL_VLVREQUEST = '2.16.840.1.113730.3.4.9';


    // MS Capabilities, Source: http://msdn.microsoft.com/en-us/library/cc223359.aspx

    // Running Active Directory as AD DS
    const LDAP_CAP_ACTIVE_DIRECTORY_OID = '1.2.840.113556.1.4.800';

    // Capable of signing and sealing on an NTLM authenticated connection
    // and of performing subsequent binds on a signed or sealed connection
    const LDAP_CAP_ACTIVE_DIRECTORY_LDAP_INTEG_OID = '1.2.840.113556.1.4.1791';

    // If AD DS: running at least W2K3, if AD LDS running at least W2K8
    const LDAP_CAP_ACTIVE_DIRECTORY_V51_OID = '1.2.840.113556.1.4.1670';

    // If AD LDS: accepts DIGEST-MD5 binds for AD LDSsecurity principals
    const LDAP_CAP_ACTIVE_DIRECTORY_ADAM_DIGEST  = '1.2.840.113556.1.4.1880';

    // Running Active Directory as AD LDS
    const LDAP_CAP_ACTIVE_DIRECTORY_ADAM_OID = '1.2.840.113556.1.4.1851';

    // If AD DS: it's a Read Only DC (RODC)
    const LDAP_CAP_ACTIVE_DIRECTORY_PARTIAL_SECRETS_OID = '1.2.840.113556.1.4.1920';

    // Running at least W2K8
    const LDAP_CAP_ACTIVE_DIRECTORY_V60_OID = '1.2.840.113556.1.4.1935';

    // Running at least W2K8r2
    const LDAP_CAP_ACTIVE_DIRECTORY_V61_R2_OID = '1.2.840.113556.1.4.2080';

    // Running at least W2K12
    const LDAP_CAP_ACTIVE_DIRECTORY_W8_OID = '1.2.840.113556.1.4.2237';

    /**
     * Attributes of the LDAP Server returned by the discovery query
     *
     * @var stdClass
     */
    private $attributes;

    /**
     * Map of supported available OIDS
     *
     * @var array
     */
    private $oids;

    /**
     * Construct a new capability
     *
     * @param $attributes   stdClass    The attributes returned, may be null for guessing default capabilities
     */
    public function __construct($attributes = null)
    {
        $this->setAttributes($attributes);
    }

    /**
     * Set the attributes and (re)build the OIDs
     *
     * @param $attributes   stdClass    The attributes returned, may be null for guessing default capabilities
     */
    protected function setAttributes($attributes)
    {
        $this->attributes = $attributes;
        $this->oids = array();

        $keys = array('supportedControl', 'supportedExtension', 'supportedFeatures', 'supportedCapabilities');
        foreach ($keys as $key) {
            if (isset($attributes->$key)) {
                if (is_array($attributes->$key)) {
                    foreach ($attributes->$key as $oid) {
                        $this->oids[$oid] = true;
                    }
                } else {
                    $this->oids[$attributes->$key] = true;
                }
            }
        }
    }

    /**
     * Return if the capability object contains support for StartTLS
     *
     * @return      bool    Whether StartTLS is supported
     */
    public function hasStartTls()
    {
        return isset($this->oids[self::LDAP_SERVER_START_TLS_OID]);
    }

    /**
     * Return if the capability object contains support for paged results
     *
     * @return      bool Whether StartTLS is supported
     */
    public function hasPagedResult()
    {
        return isset($this->oids[self::LDAP_PAGED_RESULT_OID_STRING]);
    }

    /**
     * Whether the ldap server is an ActiveDirectory server
     *
     * @return      boolean
     */
    public function isActiveDirectory()
    {
        return isset($this->oids[self::LDAP_CAP_ACTIVE_DIRECTORY_OID]);
    }

    /**
     * Whether the ldap server is an OpenLDAP server
     *
     * @return bool
     */
    public function isOpenLdap()
    {
        return isset($this->attributes->structuralObjectClass) &&
            $this->attributes->structuralObjectClass === 'OpenLDAProotDSE';
    }

    /**
     * Return if the capability objects contains support for LdapV3, defaults to true if discovery failed
     *
     * @return bool
     */
    public function hasLdapV3()
    {
        if (! isset($this->attributes) || ! isset($this->attributes->supportedLDAPVersion)) {
            // Default to true, if unknown
            return true;
        }

        return (is_string($this->attributes->supportedLDAPVersion)
            && (int) $this->attributes->supportedLDAPVersion === 3)
        || (is_array($this->attributes->supportedLDAPVersion)
            && in_array(3, $this->attributes->supportedLDAPVersion));
    }

    /**
     * Whether the capability with the given OID is supported
     *
     * @param $oid  string  The OID of the capability
     *
     * @return      bool
     */
    public function hasOid($oid)
    {
        return isset($this->oids[$oid]);
    }

    /**
     * Get the default naming context
     *
     * @return string|null the default naming context, or null when no contexts are available
     */
    public function getDefaultNamingContext()
    {
        // defaultNamingContext entry has higher priority
        if (isset($this->attributes->defaultNamingContext)) {
            return $this->attributes->defaultNamingContext;
        }

        // if its missing use namingContext
        $namingContexts = $this->namingContexts();
        return empty($namingContexts) ? null : $namingContexts[0];
    }

    /**
     * Get the configuration naming context
     *
     * @return string|null
     */
    public function getConfigurationNamingContext()
    {
        if (isset($this->attributes->configurationNamingContext)) {
            return $this->attributes->configurationNamingContext;
        }
    }

    /**
     * Get the NetBIOS name
     *
     * @return string|null
     */
    public function getNetBiosName()
    {
        if (isset($this->attributes->nETBIOSName)) {
            return $this->attributes->nETBIOSName;
        }
    }

    /**
     * Fetch the namingContexts
     *
     * @return array    the available naming contexts
     */
    public function namingContexts()
    {
        if (!isset($this->attributes->namingContexts)) {
            return array();
        }
        if (!is_array($this->attributes->namingContexts)) {
            return array($this->attributes->namingContexts);
        }
        return$this->attributes->namingContexts;
    }

    public function getVendor()
    {
        /*
         rfc #3045 specifies that the name of the server MAY be included in the attribute 'verndorName',
         AD and OpenLDAP don't do this, but for all all other vendors we follow the standard and
         just hope for the best.
        */

        if ($this->isActiveDirectory()) {
            return 'Microsoft Active Directory';
        }

        if ($this->isOpenLdap()) {
            return 'OpenLDAP';
        }

        if (! isset($this->attributes->vendorName)) {
            return null;
        }
        return $this->attributes->vendorName;
    }

    public function getVersion()
    {
        /*
         rfc #3045 specifies that the version of the server MAY be included in the attribute 'vendorVersion',
         but AD and OpenLDAP don't do this. For OpenLDAP there is no way to query the server versions, but for all
         all other vendors we follow the standard and just hope for the best.
        */

        if ($this->isActiveDirectory()) {
            return $this->getAdObjectVersionName();
        }

        if (! isset($this->attributes->vendorVersion)) {
            return null;
        }
        return $this->attributes->vendorVersion;
    }

    /**
     * Discover the capabilities of the given LDAP server
     *
     * @param   LdapConnection  $connection The ldap connection to use
     *
     * @return  LdapCapabilities
     *
     * @throws  LdapException       In case the capability query has failed
     */
    public static function discoverCapabilities(LdapConnection $connection)
    {
        $ds = $connection->getConnection();

        $fields = array(
            'configurationNamingContext',
            'defaultNamingContext',
            'namingContexts',
            'vendorName',
            'vendorVersion',
            'supportedSaslMechanisms',
            'dnsHostName',
            'schemaNamingContext',
            'supportedLDAPVersion', // => array(3, 2)
            'supportedCapabilities',
            'supportedControl',
            'supportedExtension',
            'objectVersion',
            '+'
        );

        $result = @ldap_read($ds, '', (string) $connection->select()->from('*', $fields), $fields);
        if (! $result) {
            throw new LdapException(
                'Capability query failed (%s; Default port: %d): %s. Check if hostname and port'
                . ' of the ldap resource are correct and if anonymous access is permitted.',
                $connection->getHostname(),
                $connection->getPort(),
                ldap_error($ds)
            );
        }

        $entry = ldap_first_entry($ds, $result);
        if ($entry === false) {
            throw new LdapException(
                'Capabilities not available (%s; Default port: %d): %s. Discovery of root DSE probably not permitted.',
                $connection->getHostname(),
                $connection->getPort(),
                ldap_error($ds)
            );
        }

        $cap = new LdapCapabilities($connection->cleanupAttributes(ldap_get_attributes($ds, $entry), $fields));
        $cap->discoverAdConfigOptions($connection);

        if (isset($cap->attributes) && Logger::getInstance()->getLevel() === Logger::DEBUG) {
            Logger::debug('Capability query discovered the following attributes:');
            foreach ($cap->attributes as $name => $value) {
                if ($value !== null) {
                    Logger::debug(' %s = %s', $name, $value);
                }
            }
            Logger::debug('Capability query attribute listing ended.');
        }

        return $cap;
    }

    /**
     * Discover the AD-specific configuration options of the given LDAP server
     *
     * @param   LdapConnection  $connection The ldap connection to use
     *
     * @throws  LdapException       In case the configuration options query has failed
     */
    protected function discoverAdConfigOptions(LdapConnection $connection)
    {
        if ($this->isActiveDirectory()) {
            $configurationNamingContext = $this->getConfigurationNamingContext();
            $defaultNamingContext = $this->getDefaultNamingContext();
            if (!($configurationNamingContext === null || $defaultNamingContext === null)) {
                $ds = $connection->bind()->getConnection();
                $adFields = array('nETBIOSName');
                $partitions = 'CN=Partitions,' . $configurationNamingContext;

                $result = @ldap_list(
                    $ds,
                    $partitions,
                    (string) $connection->select()->from('*', $adFields)->where('nCName', $defaultNamingContext),
                    $adFields
                );
                if ($result) {
                    $entry = ldap_first_entry($ds, $result);
                    if ($entry === false) {
                        throw new LdapException(
                            'Configuration options not available (%s:%d). Discovery of "%s" probably not permitted.',
                            $connection->getHostname(),
                            $connection->getPort(),
                            $partitions
                        );
                    }

                    $this->setAttributes((object) array_merge(
                        (array) $this->attributes,
                        (array) $connection->cleanupAttributes(ldap_get_attributes($ds, $entry), $adFields)
                    ));
                } else {
                    if (ldap_errno($ds) !== 1) {
                        // One stands for "operations error" which occurs if not bound non-anonymously.

                        throw new LdapException(
                            'Configuration options query failed (%s:%d): %s. Check if hostname and port of the'
                            . ' ldap resource are correct and if anonymous access is permitted.',
                            $connection->getHostname(),
                            $connection->getPort(),
                            ldap_error($ds)
                        );
                    }
                }
            }
        }
    }

    /**
     * Determine the active directory version using the available capabillities
     *
     * @return null|string  The server version description or null when unknown
     */
    protected function getAdObjectVersionName()
    {
        if (isset($this->oids[self::LDAP_CAP_ACTIVE_DIRECTORY_W8_OID])) {
            return 'Windows Server 2012 (or newer)';
        }
        if (isset($this->oids[self::LDAP_CAP_ACTIVE_DIRECTORY_V61_R2_OID])) {
            return 'Windows Server 2008 R2 (or newer)';
        }
        if (isset($this->oids[self::LDAP_CAP_ACTIVE_DIRECTORY_V60_OID])) {
            return 'Windows Server 2008 (or newer)';
        }
        return null;
    }
}