我有一个上传脚本，我在网上找到并修改了一点。我需要一种方法来确保上传的每个文件都有一个唯一的名称;一开始就很简短，随着文件数量的增加，名称的长度也会增加。我用过的脚本是......
<?php
// Folder to upload files to. Must end with slash /
define('DESTINATION_FOLDER','../uploads/');
// Maximum allowed file size, Kb
// Set to zero to allow any size
define('MAX_FILE_SIZE', 10240);
// Upload success URL. User will be redirected to this page after upload.
define('SUCCESS_URL','my info');
// Allowed file extensions. Will only allow these extensions if not empty.
// Example: $exts = array('avi','mov','doc');
$exts = array('jpg', 'jpeg', 'png', 'gif');
// rename file after upload? false - leave original, true - rename to some unique filename
define('RENAME_FILE', true);
// put a string to append to the uploaded file name (after extension);
// this will reduce the risk of being hacked by uploading potentially unsafe files;
// sample strings: aaa, my, etc.
define('APPEND_STRING', '');
// Need uploads log? Logs would be saved in the MySql database.
define('DO_LOG', true);
// MySql data (in case you want to save uploads log)
define('DB_HOST','my info'); // host, usually localhost
define('DB_DATABASE','my info'); // database name
define('DB_USERNAME','my info'); // username
define('DB_PASSWORD','my info'); // password
/*CREATE TABLE uploads_log (
log_id int(11) unsigned NOT NULL auto_increment,
log_filename varchar(128) default '',
log_size int(10) default 0,
log_ip varchar(24) default '',
log_date timestamp,
PRIMARY KEY (log_id),
KEY (log_filename)
);*/
####################################################################
### END OF SETTINGS. DO NOT CHANGE BELOW
####################################################################
// Allow script to work long enough to upload big files (in seconds, 2 days by default)
@set_time_limit(172800);
// following may need to be uncommented in case of problems
// ini_set("session.gc_maxlifetime","10800");
function showUploadForm($message='') {
$max_file_size_tag = '';
if (MAX_FILE_SIZE > 0) {
// convert to bytes
$max_file_size_tag = "<input name='MAX_FILE_SIZE' value='".(MAX_FILE_SIZE*1024)."' type='hidden' >\n";
}
// Load form template
include ('index.php');
}
// errors list
$errors = array();
$message = '';
// we should not exceed php.ini max file size
$ini_maxsize = ini_get('upload_max_filesize');
if (!is_numeric($ini_maxsize)) {
if (strpos($ini_maxsize, 'M') !== false)
$ini_maxsize = intval($ini_maxsize)*1024*1024;
elseif (strpos($ini_maxsize, 'K') !== false)
$ini_maxsize = intval($ini_maxsize)*1024;
elseif (strpos($ini_maxsize, 'G') !== false)
$ini_maxsize = intval($ini_maxsize)*1024*1024*1024;
}
if ($ini_maxsize < MAX_FILE_SIZE*1024) {
$errors[] = "Alert! Maximum upload file size in php.ini (upload_max_filesize) is less than script's MAX_FILE_SIZE";
}
// show upload form
if (!isset($_POST['submit'])) {
showUploadForm(join('',$errors));
}
// process file upload
else {
while(true) {
// make sure destination folder exists
if (!@file_exists(DESTINATION_FOLDER)) {
$errors[] = "Destination folder does not exist or no permissions to see it.";
break;
}
// check for upload errors
$error_code = $_FILES['filename']['error'];
if ($error_code != UPLOAD_ERR_OK) {
switch($error_code) {
case UPLOAD_ERR_INI_SIZE:
// uploaded file exceeds the upload_max_filesize directive in php.ini
$errors[] = "File is too big (1).";
break;
case UPLOAD_ERR_FORM_SIZE:
// uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form
$errors[] = "File is too big (2).";
break;
case UPLOAD_ERR_PARTIAL:
// uploaded file was only partially uploaded.
$errors[] = "Could not upload file (1).";
break;
case UPLOAD_ERR_NO_FILE:
// No file was uploaded
$errors[] = "Could not upload file (2).";
break;
case UPLOAD_ERR_NO_TMP_DIR:
// Missing a temporary folder
$errors[] = "Could not upload file (3).";
break;
case UPLOAD_ERR_CANT_WRITE:
// Failed to write file to disk
$errors[] = "Could not upload file (4).";
break;
case 8:
// File upload stopped by extension
$errors[] = "Could not upload file (5).";
break;
} // switch
// leave the while loop
break;
}
// get file name (not including path)
$filename = @basename($_FILES['filename']['name']);
// filename of temp uploaded file
$tmp_filename = $_FILES['filename']['tmp_name'];
$file_ext = @strtolower(@strrchr($filename,"."));
if (@strpos($file_ext,'.') === false) { // no dot? strange
$errors[] = "Suspicious file name or could not determine file extension.";
break;
}
$file_ext = @substr($file_ext, 1); // remove dot
// check file type if needed
if (count($exts)) { /// some day maybe check also $_FILES['user_file']['type']
if (!@in_array($file_ext, $exts)) {
$errors[] = "Files of this type are not allowed for upload.";
break;
}
}
// destination filename, rename if set to
$dest_filename = $filename;
if (RENAME_FILE) {
$dest_filename = md5(uniqid(rand(), true)) . '.' . $file_ext;
}
// append predefined string for safety
$dest_filename = $dest_filename . APPEND_STRING;
// get size
$filesize = intval($_FILES["filename"]["size"]); // filesize($tmp_filename);
// make sure file size is ok
if (MAX_FILE_SIZE > 0 && MAX_FILE_SIZE*1024 < $filesize) {
$errors[] = "File is too big (3).";
break;
}
if (!@move_uploaded_file($tmp_filename , DESTINATION_FOLDER . $dest_filename)) {
$errors[] = "Could not upload file (6).";
break;
}
if (DO_LOG) {
// Establish DB connection
$link = @mysql_connect(DB_HOST, DB_USERNAME, DB_PASSWORD);
if (!$link) {
$errors[] = "Could not connect to mysql.";
break;
}
$res = @mysql_select_db(DB_DATABASE, $link);
if (!$res) {
$errors[] = "Could not select database.";
break;
}
/*$m_ip = mysql_real_escape_string($_SERVER['REMOTE_ADDR']);
$m_size = $filesize;
$m_fname = mysql_real_escape_string($dest_filename);
$sql = "insert into _uploads_log (log_filename,log_size,log_ip) values ('$m_fname','$m_size','$m_ip')";
$res = @mysql_query($sql);
if (!$res) {
$errors[] = "Could not run query.";
break;
}*/
@mysql_free_result($res);
@mysql_close($link);
} // if (DO_LOG)
// redirect to upload success url
header('Location: ' . SUCCESS_URL);
die();
break;
} // while(true)
// Errors. Show upload form.
$message = join('',$errors);
showUploadForm($message);
}
?>
另外，我应该使用哪些其他安全程序？如果您知道，请将它们实施到我的代码中并重新发布？谢谢!!!
答案 0 :(得分：0)
您发布的代码已包含以下行：
if (RENAME_FILE) {
$dest_filename = md5(uniqid(rand(), true)) . '.' . $file_ext;
}
这是在PHP中生成随机唯一文件名的绝佳方法。 md5()返回的字符串长度为32个字符;你可以安全地截断它，但是如果你大约低于16个字符左右，你就会开始冒险碰撞。
当然，如果你想让确定没有冲突，你可以随时检查文件是否存在，如果存在则重试。这甚至可以让你使用更短的文件名：
if (RENAME_FILE) {
do {
$dest_filename = substr(md5(uniqid(rand(), true)), 0, 8) . ".$file_ext";
} while (file_exists(DESTINATION_FOLDER . $dest_filename . APPEND_STRING));
}
这应该为您提供一个唯一的8个字符（+扩展名）文件名。当然，这将在大约2 31 ≈20亿上传文件后开始放缓，并且将在2 32 ≈40亿时完全失败。