* @link https://github.com/Raruto/tile-proxy-php
* @license https://www.gnu.org/licenses/gpl-3.0.txt GNU/GPLv3
*/
// TODO: code refactoring ( wrap it within a dedicated class.. )
// User configs.
require_once 'config.php';
// Default configs.
$servers = @$config['servers'] ?: array(
'osm' => 'https://{switch:a,b,c}.tile.openstreetmap.org/{z}/{x}/{y}.png',
'otm' => 'https://{switch:a,b,c}.tile.opentopomap.org/{z}/{x}/{y}.png',
);
$bbox = @$config['bbox'] ?: '-180,-90,180,90';
$ttl = @$config['ttl'] ?: 86400;
$headers = array_change_key_case(
@$config['headers'] ?: array(
'Access-Control-Allow-Origin:' => '*',
), CASE_LOWER
);
$bbox = empty( $_GET['bbox'] ) ? $bbox : $_GET['bbox'];
$z = intval( $_GET['z'] );
$x = intval( $_GET['x'] );
$y = intval( $_GET['y'] );
$r = strip_tags( $_GET['r'] );
// allow only servers wich are defined within the tiles-config.php.
if ( ! isset( $servers[ $r ] ) ) {
print_404_page();
exit;
}
/* // proxy //////////////////////////////////////////////////////////// */
$url = generate_tile_server_url( $servers[ $r ] );
$folder = "${r}/${z}/${x}";
$file = $folder . "/${y}.png";
$bbox = explode( ',', $bbox );
$bbox_left = $bbox[0];
$bbox_bottom = $bbox[1];
$bbox_right = $bbox[2];
$bbox_top = $bbox[3];
// useful parameters to detect which tiles are within the bbox area.
$min_tile_x = lng_to_tile_x( $bbox_left, $z );
$max_tile_x = lng_to_tile_x( $bbox_right, $z );
$min_tile_y = lat_to_tile_y( $bbox_top, $z );
$max_tile_y = lat_to_tile_y( $bbox_bottom, $z );
$num_tiles_row = ( $max_tile_x - $min_tile_x ) + 1;
$num_tiles_col = ( $max_tile_y - $min_tile_y ) + 1;
$num_tiles_bbox = $num_tiles_row * $num_tiles_col;
// if (x, y, z) out bbox range: we don't cache it on this server.
if ( ! in_range( $x, $min_tile_x, $max_tile_x ) || ! in_range( $y, $min_tile_y, $max_tile_y ) ) {
proxy_remote_file( $url );
exit;
}
// if (x, y, z) in bbox range: we cache it on this server.
if ( ! is_file( $file ) || ( is_file_expired( $file ) && remote_file_exists( $url ) ) ) {
download_remote_file( $url, $folder, $file );
}
// Send to browser any previously cached tile.
output_local_file( $file );
exit;
/* // functions ///////////////////////////////////////////////////////////// */
/**
* Generate a real tile server url
*
* @param string $url eg: 'https://{switch:a,b,c}.tile.openstreetmap.org/{z}/{x}/{y}.png'.
* @return string eg: 'https://a.tile.openstreetmap.org/0/0/0.png'.
*/
function generate_tile_server_url( $url ) {
global $z, $x, $y;
$has_matches = preg_match( '/{switch:(.*?)}/', $url, $domains );
if ( ! $has_matches ) {
$domains = [ '', '' ];
}
$domains = explode( ',', $domains[1] );
$url = preg_replace( '/{switch:(.*?)}/', '{s}', $url );
$url = preg_replace( '/{s}/', $domains[ array_rand( $domains ) ], $url );
$url = preg_replace( '/{z}/', $z, $url );
$url = preg_replace( '/{x}/', $x, $url );
$url = preg_replace( '/{y}/', $y, $url );
return $url;
}
/**
* Convert Map Degrees to Radiant
*
* @param float $deg map degrees.
* @return float
*/
function deg_to_rad( $deg ) {
return $deg * M_PI / 180;
}
/**
* Convert Map Longitude to Tile-X Coordinates
*
* @param float $lng map longitude.
* @param int $zoom map zoom level.
* @return int
*/
function lng_to_tile_x( $lng, $zoom ) {
return floor( ( ( $lng + 180 ) / 360 ) * pow( 2, $zoom ) );
}
/**
* Convert Map Latitude to Tile-Y Coordinates
*
* @param float $lat map latitude.
* @param int $zoom map zoom level.
* @return int
*/
function lat_to_tile_y( $lat, $zoom ) {
return floor( ( 1 - log( tan( deg_to_rad( $lat ) ) + 1 / cos( deg_to_rad( $lat ) ) ) / M_PI ) / 2 * pow( 2, $zoom ) );
}
/**
* Finds if a number is within a given range
*
* @param float $number number to check.
* @param float $min left range number.
* @param float $max right range number.
* @return bool
*/
function in_range( $number, $min, $max ) {
return $number >= $min && $number <= $max;
}
/**
* Check if cached file is expired
*
* @param string $file filename path.
* @return bool
*/
function is_file_expired( $file ) {
global $ttl;
return filemtime( $file ) < time() - ( $ttl * 30 );
}
/**
* Check if a remote resource exists
*
* @param string $url remote file url.
* @return bool
*/
function remote_file_exists( $url ) {
$ch = curl_init( $url );
curl_setopt( $ch, CURLOPT_NOBODY, true );
curl_setopt( $ch, CURLOPT_FOLLOWLOCATION, true );
curl_exec( $ch );
$http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
curl_close( $ch );
if ( $http_code == 200 ) {
return true;
}
return false;
}
/**
* Download a remote resource
*
* @param string $url remote file url.
* @param string $folder folder where to download the remote resource.
* @param string $file file onto download the remote resource.
* @return void
*/
function download_remote_file( $url, $folder, $file ) {
if ( ! is_dir( $folder ) ) {
mkdir( $folder, 0755, true );
}
$fp = fopen( $file, 'wb' );
$ch = curl_init( $url );
curl_setopt( $ch, CURLOPT_FILE, $fp );
curl_setopt( $ch, CURLOPT_FOLLOWLOCATION, true );
curl_setopt( $ch, CURLOPT_HEADER, 0 );
curl_exec( $ch );
curl_close( $ch );
fflush( $fp ); // need to insert this line for proper output when tile is first requested.
fclose( $fp );
}
/**
* Output a local file
*
* @param string $file file of the local resource.
* @return void
*/
function output_local_file( $file ) {
print_local_file_headers( $file );
readfile( $file );
}
/**
* Proxy a remote resource
*
* @param string $url remote file url.
* @return void
*/
function proxy_remote_file( $url ) {
$fp = @fopen( $url, 'rb' );
if ( ! $fp ) {
print_404_page();
return;
}
print_remote_file_headers( $url );
fpassthru( $fp );
}
/**
* Get remote file headers, similar to: get_headers( $url )
*
* @param string $url remote file url.
* @return array
* @link https://stackoverflow.com/a/41135574
*/
function get_remote_file_headers( $url ) {
$headers = [];
$ch = curl_init();
curl_setopt( $ch, CURLOPT_URL, $url );
curl_setopt( $ch, CURLOPT_HEADER, true );
curl_setopt( $ch, CURLOPT_FOLLOWLOCATION, true );
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, 1 );
// this function is called by curl for each header received.
curl_setopt(
$ch, CURLOPT_HEADERFUNCTION,
function( $curl, $header ) use ( &$headers ) {
$headers[] = $header;
return strlen( $header );
}
);
curl_exec( $ch );
curl_close( $ch );
return $headers;
}
/**
* Print the default apache 404 page
*
* @return void
*/
function print_404_page() {
header( $_SERVER['SERVER_PROTOCOL'] . ' 404 Not Found' );
$request_uri = htmlspecialchars( $_SERVER['REQUEST_URI'] );
echo '';
echo "404 Not FoundNot Found
The requested URL {$request_uri} was not found on this server.
";
}
/**
* Send to browser remote file headers
*
* @param string $url remote file url.
* @return void
*/
function print_remote_file_headers( $url ) {
$headers = get_remote_file_headers( $url );
print_file_headers( $headers );
}
/**
* Send to browser local file headers
*
* @param string $file local file.
* @return void
*/
function print_local_file_headers( $file ) {
global $ttl;
$exp_gmt = gmdate( 'D, d M Y H:i:s', time() + $ttl * 60 ) . ' GMT';
$mod_gmt = gmdate( 'D, d M Y H:i:s', filemtime( $file ) ) . ' GMT';
$max_age = $ttl * 60;
$headers = array(
'Expires:' => $exp_gmt,
'Last-Modified:' => $mod_gmt,
'Cache-Control:' => 'public, max-age=' . $max_age, // for MSIE 5.
'Content-Type:' => 'image/png',
);
print_file_headers( $headers );
}
/**
* Send to browser file headers filtering it with the previously array in config file
*
* @param array $file_headers eg: array( 'Content-Type:' => 'image/png' ) or array( 'Access-Control-Allow-Origin: *' ).
*
* @return void
*/
function print_file_headers( &$file_headers ) {
global $headers;
// send headers only if not previously defined in config file.
foreach ( $file_headers as $header => $value ) {
if ( is_string( $header ) ) {
header( $header . ' ' . $value );
} else {
header( $value );
}
}
// send all remaing default headers defined in config file.
foreach ( $headers as $header => $value ) {
header_remove( rtrim( $header, ':' ) );
header( $header . ' ' . $value );
}
}