<?php /* vim: set noet ts=4 sw=4 ft=php: : */

// This script will only work if included from "update-backend"!

// Fetch ip-to-country.com data and index database
function fetch_ip_to_country($root)
{
    // Files used / affected
    $ipdbt   = "ip-to-country.db~";
    $ipdbc   = "ip-to-country.dbr~";
    $ipdb    = "$root/backend/ip-to-country.db";
    $ipidx   = "$root/backend/ip-to-country.idx";

    // Create one index entry for at least
    // every '$indexby'th record in the db
    $indexby = 10000000;

    // Get last modified date of ip-to-country data
    if (file_exists($ipdb)) { $lastmod = filemtime($ipdb); }
    else { $lastmod = 0; }

    // Fetch data from server to local temporary file
    $succ = fetch_into_file("http://www.directi.com/iptocountry/" .
                            "?site=php.net&dbformat=1&lastupdate=" .
                            $lastmod, $ipdbt); 

    // No success in getting the DB
    if (!$succ) { return FALSE; }
    
    /*
     The following code checks the structure of the file
     received. If this is an updated data file, then it
     should start with a given line and end with a given line,
     and all lines inside should be 24 bytes long with a
     specific format. If the data received is not in this
     format, then we reject to replace the old file with this.
    */
                    
    // Open temporary database for reading
    $ipdbf = @fopen($ipdbt, "r");
    if (!$ipdbf) { die("Unable to open '$ipdbt' for reading"); }
    
    // Open local rewritten database for writing
    $ipdbcf = @fopen($ipdbc, "w");
    if (!$ipdbcf) { die("Unable to open '$ipdbc' for writing"); }
    
    // Initial state is the first line and
    // the file is expected to be ok
    $state = 'firstline'; $fileok = TRUE;
    
    // While we can read a line from the file 
    while (!feof($ipdbf) && ($line = fgets($ipdbf))) {
        
        // Check the input depending on the state
        switch ($state) {
            
            // First line is defined, and after it we
            // switch to the 'data' state
            case 'firstline' : 
                if (trim($line) != "#Directi IP-to-Country Db: Start") {
                    $fileok = FALSE;
                    break 2;
                } else { $state = 'data'; }
                break;
            
            // In the data state we either get the last line,
            // or we get a data line containing 24 bytes, in
            // which case we write it out to the local rewritten
            // database
            case 'data' :
                if (trim($line) == "#Directi IP-to-Country Db: End") {
                    $state = 'lastline';
                } elseif (!preg_match("!\\d{20}\\w{3}\n!", $line)) {
                    $fileok = FALSE;
                    break 2;
                } else {
                    fwrite($ipdbcf, $line);
                }
                break;
            
            // We should not receive any data after the last
            // line, only whitespace is allowed
            case 'lastline' :
                if (strlen(trim($line)) > 0) {
                    $fileok = FALSE;
                    break 2;
                }
                break;
        }
    }
    fclose($ipdbf);
    fclose($ipdbcf);
    
    // Remove the temp file. If the data is ok, move
    // it to the destination, or else delete that too
    unlink($ipdbt);
    if (file_exists($ipdbc)) {
        if (!$fileok) {
            unlink($ipdbc);
        } else {
            rename($ipdbc, $ipdb);
            create_ip_to_country_index($ipdb, $ipidx, $indexby);
        }
    }
}

// Create local index for ip-to-country.com data
function create_ip_to_country_index($ipdb, $ipidx, $indexby)
{
    // Last indexed number and last record number
    $lastidx = $recnum = 0;

    // We store the index in a PHP array temporarily
    $idx_list = [$indexby, "0,0"];

    // Open database for reading
    $ipdbf = fopen($ipdb, "r");

    // Return with error in case of we cannot open the db
    if (!$ipdbf) { die("Unable to open '$ipdb' for reading"); }

    // While we can read the file
    while (!feof($ipdbf)) {

        // Get one record
        $record = fread($ipdbf, 24);

        // Unable to read a record and not at end => error
        if (strlen($record) != 24 && !feof($ipdbf)) {
            die("Incorrect ip-to-country database format");
        }

        // This is a new record
        $recnum++;

        // Get the start of the range for this record
        $range_start = (float) substr($record, 0, 10);

        // If this range starts a new step with our granularity,
        // add a new element to the index array
        if (intval($range_start / $indexby) > $lastidx) {
            $lastidx = intval($range_start / $indexby);
            $idx_list[] = "$lastidx,$recnum";
        }
    }

    // Close the database file
    fclose($ipdbf);

    // Write out index to file
    $ipidxf = fopen($ipidx, "w");
    if (!$ipidxf) { die("Unable to open '$ipidx' for writing"); }
    fwrite($ipidxf, join("\n", $idx_list));
    fclose($ipidxf);
}