torrentpier/library/includes/functions_torrent.php

776 lines
23 KiB
PHP

<?php
/**
* MIT License
*
* Copyright (c) 2005-2017 TorrentPier
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
if (!defined('BB_ROOT')) {
die(basename(__FILE__));
}
function get_torrent_info($attach_id)
{
global $lang;
$attach_id = intval($attach_id);
$sql = "
SELECT
a.post_id, d.physical_filename, d.extension, d.tracker_status,
t.topic_first_post_id,
p.poster_id, p.topic_id, p.forum_id,
f.allow_reg_tracker
FROM
" . BB_ATTACHMENTS . " a,
" . BB_ATTACHMENTS_DESC . " d,
" . BB_POSTS . " p,
" . BB_TOPICS . " t,
" . BB_FORUMS . " f
WHERE
a.attach_id = $attach_id
AND d.attach_id = $attach_id
AND p.post_id = a.post_id
AND t.topic_id = p.topic_id
AND f.forum_id = p.forum_id
LIMIT 1
";
if (!$torrent = DB()->fetch_row($sql)) {
bb_die($lang['INVALID_ATTACH_ID']);
}
return $torrent;
}
function torrent_auth_check($forum_id, $poster_id)
{
global $userdata, $lang, $attach_config;
if (IS_ADMIN) {
return true;
}
$is_auth = auth(AUTH_ALL, $forum_id, $userdata);
if ($poster_id != $userdata['user_id'] && !$is_auth['auth_mod']) {
bb_die($lang['NOT_MODERATOR']);
} elseif (!$is_auth['auth_view'] || !$is_auth['auth_attachments'] || $attach_config['disable_mod']) {
bb_die(sprintf($lang['SORRY_AUTH_READ'], $is_auth['auth_read_type']));
}
return $is_auth;
}
function tracker_unregister($attach_id, $mode = '')
{
global $lang, $bb_cfg;
$attach_id = (int)$attach_id;
$post_id = $topic_id = $forum_id = $info_hash = null;
// Get torrent info
if ($torrent = get_torrent_info($attach_id)) {
$post_id = $torrent['post_id'];
$topic_id = $torrent['topic_id'];
$forum_id = $torrent['forum_id'];
}
if ($mode == 'request') {
if (!$torrent) {
bb_die($lang['TOR_NOT_FOUND']);
}
if (!$torrent['tracker_status']) {
bb_die('Torrent already unregistered');
}
torrent_auth_check($forum_id, $torrent['poster_id']);
}
if (!$topic_id) {
$sql = "SELECT topic_id FROM " . BB_BT_TORRENTS . " WHERE attach_id = $attach_id";
if (!$result = DB()->sql_query($sql)) {
bb_die('Could not query torrent information');
}
if ($row = DB()->sql_fetchrow($result)) {
$topic_id = $row['topic_id'];
}
}
// Unset DL-Type for topic
if ($bb_cfg['bt_unset_dltype_on_tor_unreg'] && $topic_id) {
$sql = "UPDATE " . BB_TOPICS . " SET topic_dl_type = " . TOPIC_DL_TYPE_NORMAL . " WHERE topic_id = $topic_id LIMIT 1";
if (!$result = DB()->sql_query($sql)) {
bb_die('Could not update topics table #1');
}
}
// Remove peers from tracker
$sql = "DELETE FROM " . BB_BT_TRACKER . " WHERE topic_id = $topic_id";
if (!DB()->sql_query($sql)) {
bb_die('Could not delete peers');
}
// Ocelot
if ($bb_cfg['ocelot']['enabled']) {
if ($row = DB()->fetch_row("SELECT info_hash FROM " . BB_BT_TORRENTS . " WHERE attach_id = $attach_id LIMIT 1")) {
$info_hash = $row['info_hash'];
}
ocelot_update_tracker('delete_torrent', array('info_hash' => rawurlencode($info_hash), 'id' => $topic_id));
}
// Delete torrent
$sql = "DELETE FROM " . BB_BT_TORRENTS . " WHERE attach_id = $attach_id";
if (!DB()->sql_query($sql)) {
bb_die('Could not delete torrent from torrents table');
}
// Update tracker_status
$sql = "UPDATE " . BB_ATTACHMENTS_DESC . " SET tracker_status = 0 WHERE attach_id = $attach_id LIMIT 1";
if (!DB()->sql_query($sql)) {
bb_die('Could not update torrent status #1');
}
if ($mode == 'request') {
set_die_append_msg($forum_id, $topic_id);
bb_die($lang['BT_UNREGISTERED']);
}
}
function delete_torrent($attach_id, $mode = '')
{
global $lang, $reg_mode, $topic_id;
$attach_id = intval($attach_id);
$reg_mode = $mode;
if (!$torrent = get_torrent_info($attach_id)) {
bb_die($lang['TOR_NOT_FOUND']);
}
$topic_id = $torrent['topic_id'];
$forum_id = $torrent['forum_id'];
$poster_id = $torrent['poster_id'];
if ($torrent['extension'] !== TORRENT_EXT) {
bb_die($lang['NOT_TORRENT']);
}
torrent_auth_check($forum_id, $poster_id);
tracker_unregister($attach_id);
delete_attachment(0, $attach_id);
return;
}
function change_tor_status($attach_id, $new_tor_status)
{
global $topic_id, $userdata;
$attach_id = (int)$attach_id;
$new_tor_status = (int)$new_tor_status;
if (!$torrent = get_torrent_info($attach_id)) {
bb_die($lang['TOR_NOT_FOUND']);
}
$topic_id = $torrent['topic_id'];
torrent_auth_check($torrent['forum_id'], $torrent['poster_id']);
DB()->query("
UPDATE " . BB_BT_TORRENTS . " SET
tor_status = $new_tor_status,
checked_user_id = {$userdata['user_id']},
checked_time = '" . TIMENOW . "'
WHERE attach_id = $attach_id
LIMIT 1
");
}
// Set gold/silver type for torrent
function change_tor_type($attach_id, $tor_status_gold)
{
global $topic_id, $lang, $bb_cfg;
if (!$torrent = get_torrent_info($attach_id)) {
bb_die($lang['TOR_NOT_FOUND']);
}
if (!IS_AM) {
bb_die($lang['ONLY_FOR_MOD']);
}
$topic_id = $torrent['topic_id'];
$tor_status_gold = intval($tor_status_gold);
$info_hash = null;
DB()->query("UPDATE " . BB_BT_TORRENTS . " SET tor_type = $tor_status_gold WHERE topic_id = $topic_id LIMIT 1");
// Ocelot
if ($bb_cfg['ocelot']['enabled']) {
if ($row = DB()->fetch_row("SELECT info_hash FROM " . BB_BT_TORRENTS . " WHERE topic_id = $topic_id LIMIT 1")) {
$info_hash = $row['info_hash'];
}
ocelot_update_tracker('update_torrent', array('info_hash' => rawurlencode($info_hash), 'freetorrent' => $tor_status_gold));
}
}
function tracker_register($attach_id, $mode = '', $tor_status = TOR_NOT_APPROVED, $reg_time = TIMENOW)
{
global $bb_cfg, $lang, $reg_mode, $tr_cfg;
$attach_id = intval($attach_id);
$reg_mode = $mode;
if (!$torrent = get_torrent_info($attach_id)) {
bb_die($lang['TOR_NOT_FOUND']);
}
$post_id = $torrent['post_id'];
$topic_id = $torrent['topic_id'];
$forum_id = $torrent['forum_id'];
$poster_id = $torrent['poster_id'];
$info_hash = null;
if ($torrent['extension'] !== TORRENT_EXT) {
return torrent_error_exit($lang['NOT_TORRENT']);
}
if (!$torrent['allow_reg_tracker']) {
return torrent_error_exit($lang['REG_NOT_ALLOWED_IN_THIS_FORUM']);
}
if ($post_id != $torrent['topic_first_post_id']) {
return torrent_error_exit($lang['ALLOWED_ONLY_1ST_POST_REG']);
}
if ($torrent['tracker_status']) {
return torrent_error_exit($lang['ALREADY_REG']);
}
if ($this_topic_torrents = get_registered_torrents($topic_id, 'topic')) {
return torrent_error_exit($lang['ONLY_1_TOR_PER_TOPIC']);
}
torrent_auth_check($forum_id, $torrent['poster_id']);
$filename = get_attachments_dir() . '/' . $torrent['physical_filename'];
if (!is_file($filename)) {
return torrent_error_exit('File name error');
}
if (!file_exists($filename)) {
return torrent_error_exit('File not exists');
}
if (!$tor = bdecode_file($filename)) {
return torrent_error_exit('This is not a bencoded file');
}
if ($bb_cfg['bt_disable_dht']) {
$tor['info']['private'] = (int)1;
$fp = fopen($filename, 'w+');
fwrite($fp, bencode($tor));
fclose($fp);
}
if ($bb_cfg['bt_check_announce_url']) {
include(INC_DIR . 'torrent_announce_urls.php');
$ann = (@$tor['announce']) ? $tor['announce'] : '';
$announce_urls['main_url'] = $bb_cfg['bt_announce_url'];
if (!$ann || !in_array($ann, $announce_urls)) {
$msg = sprintf($lang['INVALID_ANN_URL'], htmlspecialchars($ann), $announce_urls['main_url']);
return torrent_error_exit($msg);
}
}
$info = (@$tor['info']) ? $tor['info'] : array();
if (!isset($info['name']) || !isset($info['piece length']) || !isset($info['pieces']) || strlen($info['pieces']) % 20 != 0) {
return torrent_error_exit($lang['TORFILE_INVALID']);
}
$info_hash = pack('H*', sha1(bencode($info)));
$info_hash_sql = rtrim(DB()->escape($info_hash), ' ');
$info_hash_md5 = md5($info_hash);
// Ocelot
if ($bb_cfg['ocelot']['enabled']) {
ocelot_update_tracker('add_torrent', array('info_hash' => rawurlencode($info_hash), 'id' => $topic_id, 'freetorrent' => 0));
}
if ($row = DB()->fetch_row("SELECT topic_id FROM " . BB_BT_TORRENTS . " WHERE info_hash = '$info_hash_sql' LIMIT 1")) {
$msg = sprintf($lang['BT_REG_FAIL_SAME_HASH'], TOPIC_URL . $row['topic_id']);
bb_die($msg);
set_die_append_msg($forum_id, $topic_id);
}
$totallen = 0;
if (isset($info['length'])) {
$totallen = (float)$info['length'];
} elseif (isset($info['files']) && is_array($info['files'])) {
foreach ($info['files'] as $fn => $f) {
$totallen += (float)$f['length'];
}
} else {
return torrent_error_exit($lang['TORFILE_INVALID']);
}
$size = sprintf('%.0f', (float)$totallen);
$columns = ' info_hash, post_id, poster_id, topic_id, forum_id, attach_id, size, reg_time, tor_status';
$values = "'$info_hash_sql', $post_id, $poster_id, $topic_id, $forum_id, $attach_id, '$size', $reg_time, $tor_status";
$sql = "INSERT INTO " . BB_BT_TORRENTS . " ($columns) VALUES ($values)";
if (!DB()->sql_query($sql)) {
$sql_error = DB()->sql_error();
if ($sql_error['code'] == 1062) {
// Duplicate entry
return torrent_error_exit($lang['BT_REG_FAIL_SAME_HASH']);
}
bb_die('Could not register torrent on tracker');
}
// update tracker status for this attachment
$sql = 'UPDATE ' . BB_ATTACHMENTS_DESC . " SET tracker_status = 1 WHERE attach_id = $attach_id LIMIT 1";
if (!DB()->sql_query($sql)) {
bb_die('Could not update torrent status #2');
}
// set DL-Type for topic
if ($bb_cfg['bt_set_dltype_on_tor_reg']) {
$sql = 'UPDATE ' . BB_TOPICS . ' SET topic_dl_type = ' . TOPIC_DL_TYPE_DL . " WHERE topic_id = $topic_id LIMIT 1";
if (!$result = DB()->sql_query($sql)) {
bb_die('Could not update topics table #2');
}
}
if ($tr_cfg['tor_topic_up']) {
DB()->query("UPDATE " . BB_TOPICS . " SET topic_last_post_time = GREATEST(topic_last_post_time, " . (TIMENOW - 3 * 86400) . ") WHERE topic_id = $topic_id LIMIT 1");
}
if ($reg_mode == 'request' || $reg_mode == 'newtopic') {
set_die_append_msg($forum_id, $topic_id);
$mess = sprintf($lang['BT_REGISTERED'], DOWNLOAD_URL . $attach_id);
bb_die($mess);
}
return;
}
function send_torrent_with_passkey($filename)
{
global $attachment, $auth_pages, $userdata, $bb_cfg, $tr_cfg, $lang;
if (!$bb_cfg['bt_add_auth_key'] || $attachment['extension'] !== TORRENT_EXT || !$size = @filesize($filename)) {
return;
}
$post_id = $poster_id = $passkey_val = '';
$user_id = $userdata['user_id'];
$attach_id = $attachment['attach_id'];
if (!$passkey_key = $bb_cfg['passkey_key']) {
bb_die('Could not add passkey (wrong config $bb_cfg[\'passkey_key\'])');
}
// Get $post_id & $poster_id
foreach ($auth_pages as $rid => $row) {
if ($row['attach_id'] == $attach_id) {
$post_id = $row['post_id'];
$poster_id = $row['user_id_1'];
break;
}
}
// Get $topic_id
$topic_id_sql = 'SELECT topic_id FROM ' . BB_POSTS . ' WHERE post_id = ' . (int)$post_id;
if (!($topic_id_result = DB()->sql_query($topic_id_sql))) {
bb_die('Could not query post information');
}
$topic_id_row = DB()->sql_fetchrow($topic_id_result);
$topic_id = $topic_id_row['topic_id'];
if (!$attachment['tracker_status']) {
bb_die($lang['PASSKEY_ERR_TOR_NOT_REG']);
}
if (bf($userdata['user_opt'], 'user_opt', 'dis_passkey') && !IS_GUEST) {
bb_die('Could not add passkey');
}
if ($bt_userdata = get_bt_userdata($user_id)) {
$passkey_val = $bt_userdata['auth_key'];
}
if (!$passkey_val) {
if (!$passkey_val = generate_passkey($user_id)) {
bb_simple_die('Could not generate passkey');
} elseif ($bb_cfg['ocelot']['enabled']) {
ocelot_update_tracker('add_user', array('id' => $user_id, 'passkey' => $passkey_val));
}
}
// Ratio limits
$min_ratio = $bb_cfg['bt_min_ratio_allow_dl_tor'];
if ($min_ratio && $user_id != $poster_id && ($user_ratio = get_bt_ratio($bt_userdata)) !== null) {
if ($user_ratio < $min_ratio && $post_id) {
$dl = DB()->fetch_row("
SELECT dl.user_status
FROM " . BB_POSTS . " p
LEFT JOIN " . BB_BT_DLSTATUS . " dl ON dl.topic_id = p.topic_id AND dl.user_id = $user_id
WHERE p.post_id = $post_id
LIMIT 1
");
if (!isset($dl['user_status']) || $dl['user_status'] != DL_STATUS_COMPLETE) {
bb_die(sprintf($lang['BT_LOW_RATIO_FOR_DL'], round($user_ratio, 2), "search.php?dlu=$user_id&amp;dlc=1"));
}
}
}
// Announce URL
$ann_url = $bb_cfg['bt_announce_url'];
if (!$tor = bdecode_file($filename)) {
bb_die('This is not a bencoded file');
}
$announce = $bb_cfg['ocelot']['enabled'] ? strval($bb_cfg['ocelot']['url'] . $passkey_val . "/announce") : strval($ann_url . "?$passkey_key=$passkey_val");
// Replace original announce url with tracker default
if ($bb_cfg['bt_replace_ann_url'] || !isset($tor['announce'])) {
$tor['announce'] = $announce;
}
// Delete all additional urls
if ($bb_cfg['bt_del_addit_ann_urls'] || $bb_cfg['bt_disable_dht']) {
unset($tor['announce-list']);
} elseif (isset($tor['announce-list'])) {
$tor['announce-list'] = array_merge($tor['announce-list'], array(array($announce)));
}
// Add retracker
if (isset($tr_cfg['retracker']) && $tr_cfg['retracker']) {
if (bf($userdata['user_opt'], 'user_opt', 'user_retracker') || IS_GUEST) {
if (!isset($tor['announce-list'])) {
$tor['announce-list'] = array(
array($announce),
array($tr_cfg['retracker_host'])
);
} else {
$tor['announce-list'] = array_merge($tor['announce-list'], array(array($tr_cfg['retracker_host'])));
}
}
}
// Add publisher & topic url
$publisher_name = $bb_cfg['server_name'];
$publisher_url = make_url(TOPIC_URL . $topic_id);
$tor['publisher'] = strval($publisher_name);
unset($tor['publisher.utf-8']);
$tor['publisher-url'] = strval($publisher_url);
unset($tor['publisher-url.utf-8']);
$tor['comment'] = strval($publisher_url);
unset($tor['comment.utf-8']);
// Send torrent
$output = bencode($tor);
$dl_fname = ($bb_cfg['torrent_name_style'] ? '[' . $bb_cfg['server_name'] . '].t' . $topic_id . '.torrent' : clean_filename(basename($attachment['real_filename'])));
if (!empty($_COOKIE['explain'])) {
$out = "attach path: $filename<br /><br />";
$tor['info']['pieces'] = '[...] ' . strlen($tor['info']['pieces']) . ' bytes';
$out .= print_r($tor, true);
bb_die("<pre>$out</pre>");
}
header("Content-Type: application/x-bittorrent; name=\"$dl_fname\"");
header("Content-Disposition: attachment; filename=\"$dl_fname\"");
bb_exit($output);
}
function generate_passkey($user_id, $force_generate = false)
{
global $bb_cfg, $lang, $sql;
$user_id = (int)$user_id;
// Check if user can change passkey
if (!$force_generate) {
$sql = "SELECT user_opt FROM " . BB_USERS . " WHERE user_id = $user_id LIMIT 1";
if (!$result = DB()->sql_query($sql)) {
bb_die('Could not query userdata for passkey');
}
if ($row = DB()->sql_fetchrow($result)) {
if (bf($row['user_opt'], 'user_opt', 'dis_passkey')) {
bb_die($lang['NOT_AUTHORISED']);
}
}
}
for ($i = 0; $i < 20; $i++) {
$passkey_val = make_rand_str(BT_AUTH_KEY_LENGTH);
$old_passkey = null;
if ($row = DB()->fetch_row("SELECT auth_key FROM " . BB_BT_USERS . " WHERE user_id = $user_id LIMIT 1")) {
$old_passkey = $row['auth_key'];
}
// Insert new row
DB()->query("INSERT IGNORE INTO " . BB_BT_USERS . " (user_id, auth_key) VALUES ($user_id, '$passkey_val')");
if (DB()->affected_rows() == 1) {
return $passkey_val;
}
// Update
DB()->query("UPDATE IGNORE " . BB_BT_USERS . " SET auth_key = '$passkey_val' WHERE user_id = $user_id LIMIT 1");
if (DB()->affected_rows() == 1) {
// Ocelot
if ($bb_cfg['ocelot']['enabled']) {
ocelot_update_tracker('change_passkey', array('oldpasskey' => $old_passkey, 'newpasskey' => $passkey_val));
}
return $passkey_val;
}
}
return false;
}
function tracker_rm_torrent($topic_id)
{
return DB()->sql_query("DELETE FROM " . BB_BT_TRACKER . " WHERE topic_id = " . (int)$topic_id);
}
function tracker_rm_user($user_id)
{
return DB()->sql_query("DELETE FROM " . BB_BT_TRACKER . " WHERE user_id = " . (int)$user_id);
}
function get_registered_torrents($id, $mode)
{
$field = ($mode == 'topic') ? 'topic_id' : 'post_id';
$sql = "SELECT topic_id FROM " . BB_BT_TORRENTS . " WHERE $field = $id LIMIT 1";
if (!$result = DB()->sql_query($sql)) {
bb_die('Could not query torrent id');
}
if ($rowset = @DB()->sql_fetchrowset($result)) {
return $rowset;
} else {
return false;
}
}
function torrent_error_exit($message)
{
global $reg_mode, $return_message, $lang;
$msg = '';
if (isset($reg_mode) && ($reg_mode == 'request' || $reg_mode == 'newtopic')) {
if (isset($return_message)) {
$msg .= $return_message . '<br /><br /><hr /><br />';
}
$msg .= '<b>' . $lang['BT_REG_FAIL'] . '</b><br /><br />';
}
bb_die($msg . $message);
}
function ocelot_update_tracker($action, $updates)
{
global $bb_cfg;
$get = $bb_cfg['ocelot']['secret'] . "/update?action=$action";
foreach ($updates as $key => $value) {
$get .= "&$key=$value";
}
$max_attempts = 3;
$err = false;
if (ocelot_send_request($get, $max_attempts, $err) === false) {
return false;
}
return true;
}
function ocelot_send_request($get, $max_attempts = 1, &$err = false)
{
global $bb_cfg;
$header = "GET /$get HTTP/1.1\r\nConnection: Close\r\n\r\n";
$attempts = $sleep = $success = $response = 0;
$start_time = microtime(true);
while (!$success && $attempts++ < $max_attempts) {
if ($sleep) {
sleep($sleep);
}
// Send request
$file = fsockopen($bb_cfg['ocelot']['host'], $bb_cfg['ocelot']['port'], $error_num, $error_string);
if ($file) {
if (fwrite($file, $header) === false) {
$err = "Failed to fwrite()";
$sleep = 3;
continue;
}
} else {
$err = "Failed to fsockopen() - $error_num - $error_string";
$sleep = 6;
continue;
}
// Check for response
while (!feof($file)) {
$response .= fread($file, 1024);
}
$data_start = strpos($response, "\r\n\r\n") + 4;
$data_end = strrpos($response, "\n");
if ($data_end > $data_start) {
$data = substr($response, $data_start, $data_end - $data_start);
} else {
$data = "";
}
$status = substr($response, $data_end + 1);
if ($status == "success") {
$success = true;
}
}
return $success;
}
// bdecode: based on OpenTracker
function bdecode_file($filename)
{
$file_contents = file_get_contents($filename);
return bdecode($file_contents);
}
function bdecode($str)
{
$pos = 0;
return bdecode_r($str, $pos);
}
function bdecode_r($str, &$pos)
{
$strlen = strlen($str);
if (($pos < 0) || ($pos >= $strlen)) {
return null;
} elseif ($str[$pos] == 'i') {
$pos++;
$numlen = strspn($str, '-0123456789', $pos);
$spos = $pos;
$pos += $numlen;
if (($pos >= $strlen) || ($str[$pos] != 'e')) {
return null;
} else {
$pos++;
return floatval(substr($str, $spos, $numlen));
}
} elseif ($str[$pos] == 'd') {
$pos++;
$ret = array();
while ($pos < $strlen) {
if ($str[$pos] == 'e') {
$pos++;
return $ret;
} else {
$key = bdecode_r($str, $pos);
if ($key === null) {
return null;
} else {
$val = bdecode_r($str, $pos);
if ($val === null) {
return null;
} elseif (!is_array($key)) {
$ret[$key] = $val;
}
}
}
}
return null;
} elseif ($str[$pos] == 'l') {
$pos++;
$ret = array();
while ($pos < $strlen) {
if ($str[$pos] == 'e') {
$pos++;
return $ret;
} else {
$val = bdecode_r($str, $pos);
if ($val === null) {
return null;
} else {
$ret[] = $val;
}
}
}
return null;
} else {
$numlen = strspn($str, '0123456789', $pos);
$spos = $pos;
$pos += $numlen;
if (($pos >= $strlen) || ($str[$pos] != ':')) {
return null;
} else {
$vallen = intval(substr($str, $spos, $numlen));
$pos++;
$val = substr($str, $pos, $vallen);
if (strlen($val) != $vallen) {
return null;
} else {
$pos += $vallen;
return $val;
}
}
}
}