Source for file GeoIP.php

Documentation is available at GeoIP.php
<?php
 
// +----------------------------------------------------------------------+
// | PHP version 5                                                        |
// +----------------------------------------------------------------------+
// | Copyright (C) 2004 MaxMind LLC                                       |
// +----------------------------------------------------------------------+
// | This library is free software; you can redistribute it and/or        |
// | modify it under the terms of the GNU Lesser General Public           |
// | License as published by the Free Software Foundation; either         |
// | version 2.1 of the License, or (at your option) any later version.   |
// |                                                                      |
// | This library 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    |
// | Lesser General Public License for more details.                      |
// |                                                                      |
// | You should have received a copy of the GNU Lesser General Public     |
// | License along with this library; if not, write to the Free Software  |
// | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 |
// | USA, or view it online at http://www.gnu.org/licenses/lgpl.txt.      |
// +----------------------------------------------------------------------+
// | Authors: Jim Winstead <jimw@apache.org> (original Maxmind version)   |
// |          Hans Lellelid <hans@xmpl.org>                               |
// +----------------------------------------------------------------------+
//
// $Id: GeoIP.php,v 1.2 2005/04/27 13:16:15 hlellelid Exp $
 
/**
 * GeoIP class provides an API for performing geo-location lookups based on IP
 * address.
 * 
 * To use this class you must have a [binary version] GeoIP database. There is
 * a free GeoIP country database which can be obtained from Maxmind:
 * {@link http://www.maxmind.com/app/geoip_country}
 * 
 * 
 * <b>SIMPLE USE</b>
 * 
 * 
 * Create an instance:
 * 
 * <code>
 * $geoip = Net_GeoIP::getInstance('/path/to/geoipdb.dat', Net_GeoIP::SHARED_MEMORY);
 * </code>
 * 
 * Depending on which database you are using (free, or one of paid versions)
 * you must use appropriate lookup method:
 * 
 * <code>
 * // for free country db:
 * $country_name = $geoip->lookupCountryName($_SERVER['REMOTE_ADDR']);
 * $country_code = $geoip->lookupCountryCode($_SERVER['REMOTE_ADDR']);
 * 
 * // for [non-free] region db:
 * list($ctry_code, $region) = $geoip->lookupRegion($_SERVER['REMOTE_ADDR']);
 * 
 * // for [non-free] city db:
 * $location = $geoip->lookupLocation($_SERVER['REMOTE_ADDR']);
 * print "city: " . $location->city . ", " . $location->region;
 * print "lat: " . $location->latitude . ", long: " . $location->longitude;
 * 
 * // for organization or ISP db:
 * $org_or_isp_name = $geoip->lookupOrg($_SERVER['REMOTE_ADDR']);
 * </code>
 * 
 * 
 * <b>MULTIPLE INSTANCES</b>
 * 
 * 
 * You can have several instances of this class, one for each database file
 * you are using.  You should use the static getInstance() singleton method
 * to save on overhead of setting up database segments.  Note that only one
 * instance is stored per filename, and any flags will be ignored if an
 * instance already exists for the specifiedfilename.
 * 
 * <b>Special note on using SHARED_MEMORY flag</b>
 * 
 * If you are using SHARED_MEMORY (shmop) you can only use SHARED_MEMORY for
 * one (1) instance  (i.e. for one database). Any subsequent attempts to
 * instantiate using SHARED_MEMORY will read the same shared memory block
 * already initialized, and therefore will cause problems since the expected
 * database format won't match the database in the shared memory block.
 * 
 * Note that there is no easy way to flag "nice errors" to prevent attempts
 * to create new instances using SHARED_MEMORY flag and it is also not posible
 * (in a safe way) to allow new instances to overwrite the shared memory block.
 * 
 * In short, is you are using multiple databses, use the SHARED_MEMORY flag
 * with care.
 * 
 * 
 * <b>LOOKUPS ON HOSTNAMES</b>
 * 
 * 
 * Note that this PHP API does NOT support lookups on hostnames.  This is so
 * that the public API can be kept simple and so that the lookup functions
 * don't need to try name lookups if IP lookup fails (which would be the only
 * way to keep the API simple and support name-based lookups).
 * 
 * If you do not know the IP address, you can convert an name to IP very
 * simply using PHP native functions or other libraries:
 * 
 * <code>
 *     $geoip->lookupCountryName(gethostbyname('www.sunset.se'));
 * </code>
 * 
 * Or, if you don't know whether an address is a name or ip address, use
 * application-level logic:
 * 
 * <code>
 * if (ip2long($ip_or_name) === false) {
 *   $ip = gethostbyname($ip_or_name);
 * } else {
 *   $ip = $ip_or_name;
 * }
 * $ctry = $geoip->lookupCountryName($ip);
 * </code>
 * 
 * @author Jim Winstead <jimw@apache.org> (original Maxmind PHP API)
 * @author Hans Lellelid <hans@xmpl.org>
 * @version $Revision: 1.2 $
 * @package Net_GeoIP
 */
class Net_GeoIP
{
     
    public static $COUNTRY_CODES = array(
        "", "AP", "EU", "AD", "AE", "AF", "AG", "AI", "AL", "AM", "AN", "AO", "AQ",
        "AR", "AS", "AT", "AU", "AW", "AZ", "BA", "BB", "BD", "BE", "BF", "BG", "BH",
        "BI", "BJ", "BM", "BN", "BO", "BR", "BS", "BT", "BV", "BW", "BY", "BZ", "CA",
        "CC", "CD", "CF", "CG", "CH", "CI", "CK", "CL", "CM", "CN", "CO", "CR", "CU",
        "CV", "CX", "CY", "CZ", "DE", "DJ", "DK", "DM", "DO", "DZ", "EC", "EE", "EG",
        "EH", "ER", "ES", "ET", "FI", "FJ", "FK", "FM", "FO", "FR", "FX", "GA", "GB",
        "GD", "GE", "GF", "GH", "GI", "GL", "GM", "GN", "GP", "GQ", "GR", "GS", "GT",
        "GU", "GW", "GY", "HK", "HM", "HN", "HR", "HT", "HU", "ID", "IE", "IL", "IN",
        "IO", "IQ", "IR", "IS", "IT", "JM", "JO", "JP", "KE", "KG", "KH", "KI", "KM",
        "KN", "KP", "KR", "KW", "KY", "KZ", "LA", "LB", "LC", "LI", "LK", "LR", "LS",
        "LT", "LU", "LV", "LY", "MA", "MC", "MD", "MG", "MH", "MK", "ML", "MM", "MN",
        "MO", "MP", "MQ", "MR", "MS", "MT", "MU", "MV", "MW", "MX", "MY", "MZ", "NA",
        "NC", "NE", "NF", "NG", "NI", "NL", "NO", "NP", "NR", "NU", "NZ", "OM", "PA",
        "PE", "PF", "PG", "PH", "PK", "PL", "PM", "PN", "PR", "PS", "PT", "PW", "PY",
        "QA", "RE", "RO", "RU", "RW", "SA", "SB", "SC", "SD", "SE", "SG", "SH", "SI",
        "SJ", "SK", "SL", "SM", "SN", "SO", "SR", "ST", "SV", "SY", "SZ", "TC", "TD",
        "TF", "TG", "TH", "TJ", "TK", "TM", "TN", "TO", "TP", "TR", "TT", "TV", "TW",
        "TZ", "UA", "UG", "UM", "US", "UY", "UZ", "VA", "VC", "VE", "VG", "VI", "VN",
        "VU", "WF", "WS", "YE", "YT", "YU", "ZA", "ZM", "ZR", "ZW", "A1", "A2", "O1"
        );
 
    public static $COUNTRY_CODES3 = array(
        "","AP","EU","AND","ARE","AFG","ATG","AIA","ALB","ARM","ANT","AGO","AQ","ARG",
        "ASM","AUT","AUS","ABW","AZE","BIH","BRB","BGD","BEL","BFA","BGR","BHR","BDI",
        "BEN","BMU","BRN","BOL","BRA","BHS","BTN","BV","BWA","BLR","BLZ","CAN","CC",
        "COD","CAF","COG","CHE","CIV","COK","CHL","CMR","CHN","COL","CRI","CUB","CPV",
        "CX","CYP","CZE","DEU","DJI","DNK","DMA","DOM","DZA","ECU","EST","EGY","ESH",
        "ERI","ESP","ETH","FIN","FJI","FLK","FSM","FRO","FRA","FX","GAB","GBR","GRD",
        "GEO","GUF","GHA","GIB","GRL","GMB","GIN","GLP","GNQ","GRC","GS","GTM","GUM",
        "GNB","GUY","HKG","HM","HND","HRV","HTI","HUN","IDN","IRL","ISR","IND","IO",
        "IRQ","IRN","ISL","ITA","JAM","JOR","JPN","KEN","KGZ","KHM","KIR","COM","KNA",
        "PRK","KOR","KWT","CYM","KAZ","LAO","LBN","LCA","LIE","LKA","LBR","LSO","LTU",
        "LUX","LVA","LBY","MAR","MCO","MDA","MDG","MHL","MKD","MLI","MMR","MNG","MAC",
        "MNP","MTQ","MRT","MSR","MLT","MUS","MDV","MWI","MEX","MYS","MOZ","NAM","NCL",
        "NER","NFK","NGA","NIC","NLD","NOR","NPL","NRU","NIU","NZL","OMN","PAN","PER",
        "PYF","PNG","PHL","PAK","POL","SPM","PCN","PRI","PSE","PRT","PLW","PRY","QAT",
        "REU","ROU","RUS","RWA","SAU","SLB","SYC","SDN","SWE","SGP","SHN","SVN","SJM",
        "SVK","SLE","SMR","SEN","SOM","SUR","STP","SLV","SYR","SWZ","TCA","TCD","TF",
        "TGO","THA","TJK","TKL","TLS","TKM","TUN","TON","TUR","TTO","TUV","TWN","TZA",
        "UKR","UGA","UM","USA","URY","UZB","VAT","VCT","VEN","VGB","VIR","VNM","VUT",
        "WLF","WSM","YEM","YT","YUG","ZAF","ZMB","ZR","ZWE","A1","A2","O1");
 
    public static $COUNTRY_NAMES = array(
        "", "Asia/Pacific Region", "Europe", "Andorra", "United Arab Emirates",
        "Afghanistan", "Antigua and Barbuda", "Anguilla", "Albania", "Armenia",
        "Netherlands Antilles", "Angola", "Antarctica", "Argentina", "American Samoa",
        "Austria", "Australia", "Aruba", "Azerbaijan", "Bosnia and Herzegovina",
        "Barbados", "Bangladesh", "Belgium", "Burkina Faso", "Bulgaria", "Bahrain",
        "Burundi", "Benin", "Bermuda", "Brunei Darussalam", "Bolivia", "Brazil",
        "Bahamas", "Bhutan", "Bouvet Island", "Botswana", "Belarus", "Belize",
        "Canada", "Cocos (Keeling) Islands", "Congo, The Democratic Republic of the",
        "Central African Republic", "Congo", "Switzerland", "Cote D'Ivoire", "Cook
        Islands", "Chile", "Cameroon", "China", "Colombia", "Costa Rica", "Cuba", "Cape
        Verde", "Christmas Island", "Cyprus", "Czech Republic", "Germany", "Djibouti",
        "Denmark", "Dominica", "Dominican Republic", "Algeria", "Ecuador", "Estonia",
        "Egypt", "Western Sahara", "Eritrea", "Spain", "Ethiopia", "Finland", "Fiji",
        "Falkland Islands (Malvinas)", "Micronesia, Federated States of", "Faroe
        Islands", "France", "France, Metropolitan", "Gabon", "United Kingdom",
        "Grenada", "Georgia", "French Guiana", "Ghana", "Gibraltar", "Greenland",
        "Gambia", "Guinea", "Guadeloupe", "Equatorial Guinea", "Greece", "South Georgia
        and the South Sandwich Islands", "Guatemala", "Guam", "Guinea-Bissau",
        "Guyana", "Hong Kong", "Heard Island and McDonald Islands", "Honduras",
        "Croatia", "Haiti", "Hungary", "Indonesia", "Ireland", "Israel", "India",
        "British Indian Ocean Territory", "Iraq", "Iran, Islamic Republic of",
        "Iceland", "Italy", "Jamaica", "Jordan", "Japan", "Kenya", "Kyrgyzstan",
        "Cambodia", "Kiribati", "Comoros", "Saint Kitts and Nevis", "Korea, Democratic
        People's Republic of", "Korea, Republic of", "Kuwait", "Cayman Islands",
        "Kazakstan", "Lao People's Democratic Republic", "Lebanon", "Saint Lucia",
        "Liechtenstein", "Sri Lanka", "Liberia", "Lesotho", "Lithuania", "Luxembourg",
        "Latvia", "Libyan Arab Jamahiriya", "Morocco", "Monaco", "Moldova, Republic
        of", "Madagascar", "Marshall Islands", "Macedonia", "Mali", "Myanmar", "Mongolia", 
        "Macau", "Northern Mariana Islands",
        "Martinique", "Mauritania", "Montserrat", "Malta", "Mauritius", "Maldives",
        "Malawi", "Mexico", "Malaysia", "Mozambique", "Namibia", "New Caledonia",
        "Niger", "Norfolk Island", "Nigeria", "Nicaragua", "Netherlands", "Norway",
        "Nepal", "Nauru", "Niue", "New Zealand", "Oman", "Panama", "Peru", "French
        Polynesia", "Papua New Guinea", "Philippines", "Pakistan", "Poland", "Saint
        Pierre and Miquelon", "Pitcairn Islands", "Puerto Rico", "Palestinian Territory,
        Occupied", "Portugal", "Palau", "Paraguay", "Qatar", "Reunion", "Romania",
        "Russian Federation", "Rwanda", "Saudi Arabia", "Solomon Islands",
        "Seychelles", "Sudan", "Sweden", "Singapore", "Saint Helena", "Slovenia",
        "Svalbard and Jan Mayen", "Slovakia", "Sierra Leone", "San Marino", "Senegal",
        "Somalia", "Suriname", "Sao Tome and Principe", "El Salvador", "Syrian Arab
        Republic", "Swaziland", "Turks and Caicos Islands", "Chad", "French Southern
        Territories", "Togo", "Thailand", "Tajikistan", "Tokelau", "Turkmenistan",
        "Tunisia", "Tonga", "East Timor", "Turkey", "Trinidad and Tobago", "Tuvalu",
        "Taiwan", "Tanzania, United Republic of", "Ukraine",
        "Uganda", "United States Minor Outlying Islands", "United States", "Uruguay",
        "Uzbekistan", "Holy See (Vatican City State)", "Saint Vincent and the
        Grenadines", "Venezuela", "Virgin Islands, British", "Virgin Islands, U.S.",
        "Vietnam", "Vanuatu", "Wallis and Futuna", "Samoa", "Yemen", "Mayotte",
        "Yugoslavia", "South Africa", "Zambia", "Zaire", "Zimbabwe",
        "Anonymous Proxy","Satellite Provider","Other"
        );
            
    // storage / caching flags
    const STANDARD = 0;
    const MEMORY_CACHE = 1;
    const SHARED_MEMORY = 2;
    
    // Database structure constants
    const COUNTRY_BEGIN = 16776960;
    const STATE_BEGIN_REV0 = 16700000;
    const STATE_BEGIN_REV1 = 16000000;
 
    const STRUCTURE_INFO_MAX_SIZE = 20;
    const DATABASE_INFO_MAX_SIZE = 100;
    const COUNTRY_EDITION = 106;
    const REGION_EDITION_REV0 = 112;
    const REGION_EDITION_REV1 = 3;
    const CITY_EDITION_REV0 = 111;
    const CITY_EDITION_REV1 = 2;
    const ORG_EDITION = 110;
    const SEGMENT_RECORD_LENGTH = 3;
    const STANDARD_RECORD_LENGTH = 3;
    const ORG_RECORD_LENGTH = 4;
    const MAX_RECORD_LENGTH = 4;
    const MAX_ORG_RECORD_LENGTH = 300;
    const FULL_RECORD_LENGTH = 50;
    
    const US_OFFSET = 1;
    const CANADA_OFFSET = 677;
    const WORLD_OFFSET = 1353;
    const FIPS_RANGE = 360;        
    
    // SHMOP memory address
    const SHM_KEY = 0x4f415401;
    
    /**
     * @var int 
     */
    private $flags = 0;
    
    /**
     * @var resource 
     */
      private $filehandle;
    
    /**
     * @var string 
     */
      private $memoryBuffer;
    
    /**
     * @var int 
     */
      private $databaseType;
    
    /**
     * @var int 
     */
      private $databaseSegments;
    
    /**
     * @var int 
     */
      private $recordLength;
    
    /**
     * The memory addr "id" for use with SHMOP.
     * @var int 
     */
    private $shmid;        
    
    /** 
     * Support for singleton pattern.
     * @var array 
     */
    private static $instances = array();
        
    /**
     * Construct a Net_GeoIP instance.
     * You should use the getInstance() method if you plan to use multiple databases or
     * the same database from several different places in your script.
     * @param string $filename Path to binary geoip database.
     * @param int $flags 
     * @see getInstance()
     */
    public function __construct($filename = null, $flags = null)
    {
        if($filename !== null) {
            $this->open($filename, $flags);
        }        
        // store the instance, so that it will be returned by a call to
        // getInstance() (with the same db filename).
        self::$instances[$filename] = $this;
    }
    
    /**
     * Calls the close() function to free any resources.
     * @see close()
     *
     *  COMMENTED OUT TO ADDRESS BUG IN PHP 5.0.4, 5.0.5dev.  THIS RESOURCE
     *  SHOULD AUTOMATICALLY BE FREED AT SCRIPT CLOSE, SO A DESTRUCTOR
     *  IS A GOOD IDEA BUT NOT NECESSARILY A NECESSITY.
    public function __destruct()
    {
        $this->close();
    }
    */
    
    /**
     * Singleton method, use this to get an instance and avoid re-parsing the db.
     * 
     * Unique instances are instantiated based on the filename of the db. The flags
     * are ignored -- in that requests to for instance with same filename but different
     * flags will return the already-instantiated instance.  For example:
     * <code>
     * // create new instance with memory_cache enabled
     * $geoip = Net_GeoIP::getInstance('C:\mydb.dat', Net_GeoIP::MEMORY_CACHE);
     * ....
     * 
     * // later in code, request instance with no flags specified.
     * $geoip = Net_GeoIP::getInstance('C:\mydb.dat');
     * 
     * // Normally this means no MEMORY_CACHE but since an instance
     * // with memory cache enabled has already been created for 'C:\mydb.dat', the
     * // existing instance (with memory cache) will be returned.
     * </code>
     * 
     * NOTE: You can only use SHARED_MEMORY flag for one instance!  Any subsquent instances
     * that attempt to use the SHARED_MEMORY will use the *same* shared memory, which will break
     * your script.
     * 
     * @param string $filename 
     * @param int $flags       Flags that control class behavior.
     *                          + Net_GeoIp::SHARED_MEMORY       - use SHMOP to share a db among multiple PHP instances.
     *                                                      NOTE: ONLY ONE GEOIP INSTANCE CAN USE SHARED MEMORY!!!
     *                          + Net_GeoIp::MEMORY_CACHE        - store the full contents of the database in memory for current script.
     *                                                      This is useful if you access the database several times in a script.
     *                          + Net_GeoIp::STANDARD            - [default] standard no-cache version.
     */
    public static function getInstance($filename = null, $flags = null)
    {
        if (!isset(self::$instances[$filename])) {
            self::$instances[$filename] = new Net_GeoIP($filename, $flags);
        }
        return self::$instances[$filename];
    }
    
    /**
     * Opens geoip database at filename and with specified flags.
     * @param string $filename 
     * @param int $flags 
     * @throws Exception     - if unable to open specified file or shared memory.
     */
    public function open($filename, $flags = null)
    {    
        if ($flags !== null) {
            $this->flags = $flags;
        }        
        if ($this->flags & self::SHARED_MEMORY) {
            $this->shmid = @shmop_open(self::SHM_KEY, "a", 0, 0);
            if ($this->shmid === false) {
                $this->loadSharedMemory($filename);
                $this->shmid = @shmop_open(self::SHM_KEY, "a", 0, 0);
                if ($this->shmid === false) { // should never be false as loadSharedMemory() will throw Exc if cannot create
                    throw new Exception("Unable to open shared memory at key: " . dechex(self::SHM_KEY));
                }
            }
          } else {
            $this->filehandle = fopen($filename, "rb");
            if (!$this->filehandle) {
                throw new Exception("Unable to open file: $filename");
            }
            if ($this->flags & self::MEMORY_CACHE) {
                $s_array = fstat($this->filehandle);
                $this->memoryBuffer = fread($this->filehandle, $s_array['size']);
            }
        }
        $this->setupSegments();
    }
    
    /**
     * Loads the database file into shared memory.
     * @param string $filename Path to database file to read into shared memory.
     * @return void 
     * @throws Exception     - if unable to read the db file.
     */
    private function loadSharedMemory($filename)
    {
        $fp = fopen($filename, "rb");
        if (!$fp) {
            throw new Exception("Unable to open file: $filename");
        }
        $s_array = fstat($fp);
        $size = $s_array['size'];
        
        if ($shmid = shmop_open(self::SHM_KEY, "w", 0, 0)) {
            shmop_delete ($shmid);
            shmop_close ($shmid);
        }
        $shmid = shmop_open(self::SHM_KEY, "c", 0644, $size);
        shmop_write($shmid, fread($fp, $size), 0);
        shmop_close($shmid);
        fclose($fp);
    }
    
    /**
     * Parses the database file to determine what kind of database is being used and setup
     * segment sizes and start points that will be used by the seek*() methods later.
     * 
     * @return void 
     */
    private function setupSegments()
    {
 
        $this->databaseType = self::COUNTRY_EDITION;
        $this->recordLength = self::STANDARD_RECORD_LENGTH;
            
        if ($this->flags & self::SHARED_MEMORY) {
            
            $offset = shmop_size($this->shmid) - 3;
            for ($i = 0; $i < self::STRUCTURE_INFO_MAX_SIZE; $i++) {
                $delim = shmop_read($this->shmid, $offset, 3);
                $offset += 3;
                if ($delim == (chr(255).chr(255).chr(255))) {
                    $this->databaseType = ord(shmop_read($this->shmid, $offset, 1));
                    $offset++;
                    if ($this->databaseType === self::REGION_EDITION_REV0) {
                        $this->databaseSegments = self::STATE_BEGIN_REV0;
                    } elseif ($this->databaseType === self::REGION_EDITION_REV1) {
                        $this->databaseSegments = self::STATE_BEGIN_REV1;
                     } elseif (($this->databaseType === self::CITY_EDITION_REV0) 
                                || ($this->databaseType === self::CITY_EDITION_REV1) 
                                || ($this->databaseType === self::ORG_EDITION)) {
                        $this->databaseSegments = 0;
                        $buf = shmop_read($this->shmid, $offset, self::SEGMENT_RECORD_LENGTH);
                        for ($j = 0; $j < self::SEGMENT_RECORD_LENGTH; $j++) {
                            $this->databaseSegments += (ord($buf[$j]) << ($j * 8));
                        }
                         if ($this->databaseType === self::ORG_EDITION) {
                            $this->recordLength = self::ORG_RECORD_LENGTH;
                        }
                    }
                    break;
                } else {
                    $offset -= 4;
                }
            }
            if ($this->databaseType == self::COUNTRY_EDITION) {
                $this->databaseSegments = self::COUNTRY_BEGIN;
            }
            
        } else {
        
            $filepos = ftell($this->filehandle);
            fseek($this->filehandle, -3, SEEK_END);
            for ($i = 0; $i < self::STRUCTURE_INFO_MAX_SIZE; $i++) {
                $delim = fread($this->filehandle, 3);
                if ($delim == (chr(255).chr(255).chr(255))) {
                    $this->databaseType = ord(fread($this->filehandle,1));
                    if ($this->databaseType === self::REGION_EDITION_REV0) {
                        $this->databaseSegments = self::STATE_BEGIN_REV0;
                    } elseif($this->databaseType === self::REGION_EDITION_REV1) { 
                        $this->databaseSegments = self::STATE_BEGIN_REV1;
                    } elseif ($this->databaseType === self::CITY_EDITION_REV0 
                                || $this->databaseType === self::CITY_EDITION_REV1
                                || $this->databaseType === self::ORG_EDITION) {
                        $this->databaseSegments = 0;
                        $buf = fread($this->filehandle, self::SEGMENT_RECORD_LENGTH);
                        for ($j = 0; $j < self::SEGMENT_RECORD_LENGTH; $j++) {
                            $this->databaseSegments += (ord($buf[$j]) << ($j * 8));
                        }
                        if ($this->databaseType === self::ORG_EDITION) {
                            $this->recordLength = self::ORG_RECORD_LENGTH;
                        }
                    }
                  break;
                } else {
                    fseek($this->filehandle, -4, SEEK_CUR);
                }
            }
            if ($this->databaseType === self::COUNTRY_EDITION){
                $this->databaseSegments = self::COUNTRY_BEGIN;
            }
            fseek($this->filehandle, $filepos, SEEK_SET);
            
        }
    }
        
    /**
     * Closes the geoip database.
     * @return int Status of close command.
     */
    public function close()
    {
        if ($this->flags & self::SHARED_MEMORY) {
            return shmop_close($this->shmid);
        } else {
            // right now even if file was cached in RAM the file was not closed
            // so it's safe to expect no error w/ fclose()
            return fclose($this->filehandle);
        }        
    }
    
    /**
     * Get the country index.
     * 
     * This method is called by the lookupCountryCode() and lookupCountryName()
     * methods.  It lookups up the index ('id') for the country which is the key
     * for the code and name.
     * 
     * @param string $addr 
     * @throws Exception     - if IP address is invalid.
     *                          - if database type is incorrect
     */
    private function lookupCountryId($addr)
    {        
        $ipnum = ip2long($addr);
        if ($ipnum === false) {
            throw new Exception("Invalid IP address: " . var_export($addr, true));
        }
        if ($this->databaseType !== self::COUNTRY_EDITION) {
            throw new Exception("Invalid database type; lookupCountry*() methods expect Country database.");
        }
        return $this->seekCountry($ipnum) - self::COUNTRY_BEGIN;
    }
    
    /**
     * Returns 2-letter country code (e.g. 'CA') for specified IP address.
     * Use this method if you have a Country database.
     * @param string $addr IP address (hostname not allowed).
     * @return string 2-letter country code
     * @throws Exception (see lookupCountryId())
     * @see lookupCountryId()
     */
    public function lookupCountryCode($addr)
    {
        return self::$COUNTRY_CODES[$this->lookupCountryId($addr)];
    }
    
    /**
     * Returns full country name for specified IP address.
     * Use this method if you have a Country database.
     * @param string $addr IP address (hostname not allowed).
     * @return string Country name
     * @throws Exception (see lookupCountryId())
     * @see lookupCountryId()
     */
    public function lookupCountryName($addr)
    {
        return self::$COUNTRY_NAMES[$this->lookupCountryId($addr)];
    }
    
    /**
     * Using the record length and appropriate start points, seek to the country that corresponds
     * to the converted IP address integer.
     * @param int $ipnum Result of ip2long() conversion.
     * @return int Offset of start of record.
     * @throws Exception - if fseek() fails on the file or no results after traversing the database (indicating corrupt db).
     */
    private function seekCountry($ipnum)
    {
        $offset = 0;
        for ($depth = 31; $depth >= 0; --$depth) {
            if ($this->flags & self::MEMORY_CACHE) {
                  $buf = substr($this->memoryBuffer, 2 * $this->recordLength * $offset, 2 * $this->recordLength);
            } elseif ($this->flags & self::SHARED_MEMORY) {
                $buf = shmop_read ($this->shmid, 2 * $this->recordLength * $offset, 2 * $this->recordLength );
            } else {
                if (fseek($this->filehandle, 2 * $this->recordLength * $offset, SEEK_SET) !== 0) {
                    throw new Exception("fseek failed");
                }                
                $buf = fread($this->filehandle, 2 * $this->recordLength);
            }
            $x = array(0,0);
            for ($i = 0; $i < 2; ++$i) {
                for ($j = 0; $j < $this->recordLength; ++$j) {
                    $x[$i] += ord($buf[$this->recordLength * $i + $j]) << ($j * 8);
                }
            }
            if ($ipnum & (1 << $depth)) {
                if ($x[1] >= $this->databaseSegments) {
                    return $x[1];
                }
                $offset = $x[1];
            } else {
                if ($x[0] >= $this->databaseSegments) {
                    return $x[0];
                }
                $offset = $x[0];
            }                              
        }
        throw new Exception("Error traversing database - perhaps it is corrupt?");        
    }
 
    /**
     * Lookup the organization (or ISP) for given IP address.
     * Use this method if you have an Organization/ISP database.
     * @param string $addr IP address (hostname not allowed).
     * @throws Exception     - if IP address is invalid.
     *                          - if database is of wrong type
     */
    public function lookupOrg($addr)
    {
        $ipnum = ip2long($addr);
        if ($ipnum === false) {
           throw new Exception("Invalid IP address: " . var_export($addr, true));
        }
        if ($this->databaseType !== self::ORG_EDITION) {
            throw new Exception("Invalid database type; lookupOrg() method expects Org/ISP database.");
        }
        return $this->getOrg($ipnum);
    }
    
    /**
     * Lookup the region for given IP address.
     * Use this method if you have a Region database.
     * @param string $addr IP address (hostname not allowed).
     * @return array Array containing country code and region: array($country_code, $region)
     * @throws Exception - if IP address is invalid.
     */
    public function lookupRegion($addr)
    {
        $ipnum = ip2long($addr);
        if ($ipnum === false) {
            throw new Exception("Invalid IP address: " . var_export($addr, true));
        }
        if ($this->databaseType !== self::REGION_EDITION_REV0 && $this->databaseType !== self::REGION_EDITION_REV1) {
            throw new Exception("Invalid database type; lookupRegion() method expects Region database.");
        }
        return $this->getRegion($ipnum);
    }    
        
    /**
     * Lookup the location record for given IP address.
     * Use this method if you have a City database.
     * @param string $addr IP address (hostname not allowed).
     * @return Net_GeoIP_Location The full location record.
     * @throws Exception - if IP address is invalid.
     */
    public function lookupLocation($addr)
    {
        require_once 'Net/GeoIP/Location.php';
        $ipnum = ip2long($addr);
        if ($ipnum === false) {
            throw new Exception("Invalid IP address: " . var_export($addr, true));
        }
        if ($this->databaseType !== self::CITY_EDITION_REV0 && $this->databaseType !== self::CITY_EDITION_REV1) {
            throw new Exception("Invalid database type; lookupLocation() method expects City database.");
        }
        return $this->getRecord($ipnum);
    }
 
    /**
     * Seek and return organization (or ISP) name for converted IP addr.
     * @param int $ipnum Converted IP address.
     * @todo -cGeoIP Consider adding MEMORY_CACHE support to the getOrg() method (if there is a perf. difference).
     */
    private function getOrg($ipnum)
    {
        $seek_org = $this->seekCountry($ipnum);
        if ($seek_org == $this->databaseSegments) {
            return null;
        }
        $record_pointer = $seek_org + (2 * $this->recordLength - 1) * $this->databaseSegments;
        if ($this->flags & self::SHARED_MEMORY) {
            $org_buf = shmop_read($this->shmid, $record_pointer, self::MAX_ORG_RECORD_LENGTH);
        } else {
            fseek($this->filehandle, $record_pointer, SEEK_SET);
            $org_buf = fread($this->filehandle, self::MAX_ORG_RECORD_LENGTH);
        }
        $org_buf = substr($org_buf, 0, strpos($org_buf, 0));
        return $org_buf;
    }
 
    /**
     * Seek and return the region info (array containing country code and region name) for converted IP addr.
     * @param int $ipnum Converted IP address.
     * @return array Array containing country code and region: array($country_code, $region)
     */
    private function getRegion($ipnum)
    {
        if ($this->databaseType == self::REGION_EDITION_REV0) {
            $seek_region = $this->seekCountry($ipnum) - self::STATE_BEGIN_REV0;
            if ($seek_region >= 1000){
                $country_code = "US";
                $region = chr(($seek_region - 1000)/26 + 65) . chr(($seek_region - 1000)%26 + 65);
            } else {
                $country_code = self::$COUNTRY_CODES[$seek_region];
                $region = "";
            }
            return array($country_code, $region);
        } elseif ($this->databaseType == self::REGION_EDITION_REV1) {
            $seek_region = $this->seekCountry($ipnum) - self::STATE_BEGIN_REV1;
            //print $seek_region;
            if ($seek_region < self::US_OFFSET){
                $country_code = "";
                $region = "";  
            } elseif ($seek_region < self::CANADA_OFFSET){
                $country_code = "US";
                $region = chr(($seek_region - self::US_OFFSET)/26 + 65) . chr(($seek_region - self::US_OFFSET)%26 + 65);
            } elseif ($seek_region < self::WORLD_OFFSET){
                $country_code = "CA";
                $region = chr(($seek_region - self::CANADA_OFFSET)/26 + 65) . chr(($seek_region - self::CANADA_OFFSET)%26 + 65);
            } else {
                $country_code = self::$COUNTRY_CODES[($seek_region - self::WORLD_OFFSET) / self::FIPS_RANGE];
                $region = "";
            }
            return array ($country_code,$region);
        }
    }
    
    /**
     * Seek and populate Net_GeoIP_Location object for converted IP addr.
     * Note: this
     * @param int $ipnum Converted IP address.
     * @return Net_GeoIP_Location 
     */
    private function getRecord($ipnum)
    {
        $seek_country = $this->seekCountry($ipnum);
        if ($seek_country == $this->databaseSegments) {
            return null;
        }
        
        $record_pointer = $seek_country + (2 * $this->recordLength - 1) * $this->databaseSegments;
        
        if ($this->flags & self::SHARED_MEMORY) {
            $record_buf = shmop_read($this->shmid, $record_pointer, self::FULL_RECORD_LENGTH);
        } else {
            fseek($this->filehandle, $record_pointer, SEEK_SET);
            $record_buf = fread($this->filehandle, self::FULL_RECORD_LENGTH);        
        }
        
        $record = new Net_GeoIP_Location();
        
        $record_buf_pos = 0;
        $char = ord(substr($record_buf, $record_buf_pos, 1));
        $record->countryCode = self::$COUNTRY_CODES[$char];
        $record->countryCode3 = self::$COUNTRY_CODES3[$char];
        $record->countryName = self::$COUNTRY_NAMES[$char];
        $record_buf_pos++;
        $str_length = 0;
  
        //get region
        $char = ord(substr($record_buf,$record_buf_pos+$str_length,1));
        while ($char != 0){
            $str_length++;
            $char = ord(substr($record_buf,$record_buf_pos+$str_length,1));
        }
        if ($str_length > 0){
            $record->region = substr($record_buf,$record_buf_pos,$str_length);
        }
        $record_buf_pos += $str_length + 1;
        $str_length = 0;
 
        //get city
        $char = ord(substr($record_buf,$record_buf_pos+$str_length,1));
        while ($char != 0){
            $str_length++;
            $char = ord(substr($record_buf,$record_buf_pos+$str_length,1));
        }
        if ($str_length > 0){
            $record->city = substr($record_buf,$record_buf_pos,$str_length);
        }
        $record_buf_pos += $str_length + 1;
        $str_length = 0;
 
        //get postal code
        $char = ord(substr($record_buf,$record_buf_pos+$str_length,1));
        while ($char != 0){
            $str_length++;
            $char = ord(substr($record_buf,$record_buf_pos+$str_length,1));
        }
        if ($str_length > 0){
            $record->postalCode = substr($record_buf,$record_buf_pos,$str_length);
        }
        $record_buf_pos += $str_length + 1;
        $str_length = 0;
        $latitude = 0;
        $longitude = 0;
        for ($j = 0;$j < 3; ++$j){
            $char = ord(substr($record_buf, $record_buf_pos++, 1));
            $latitude += ($char << ($j * 8));
        }
        $record->latitude = ($latitude/10000) - 180;
 
        for ($j = 0;$j < 3; ++$j){
            $char = ord(substr($record_buf,$record_buf_pos++,1));
            $longitude += ($char << ($j * 8));
        }
        $record->longitude = ($longitude/10000) - 180;
                
        if ($this->databaseType === self::CITY_EDITION_REV1){
            $dmaarea_combo = 0;
            if ($record->countryCode == "US"){
                for ($j = 0;$j < 3;++$j){
                    $char = ord(substr($record_buf, $record_buf_pos++, 1));
                    $dmaarea_combo += ($char << ($j * 8));
                }
                $record->dmaCode = floor($dmaarea_combo/1000);
                $record->areaCode = $dmaarea_combo%1000;
            }
        }
        return $record;
    }
 
}