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Web Programming Week 10

Web Programming Week 10. Old Dominion University Department of Computer Science CS 418/518 Fall 2010 Martin Klein <mklein@cs.odu.edu> 11/02/10. Protect Files - htaccess. Apache syntax: place file .htaccess into directory you want to protect specify: AuthType Basic|Digest

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Web Programming Week 10

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  1. Web ProgrammingWeek 10 Old Dominion University Department of Computer Science CS 418/518 Fall 2010 Martin Klein <mklein@cs.odu.edu> 11/02/10

  2. Protect Files - htaccess • Apache syntax: • place file .htaccess into directory you want to protect • specify: • AuthType Basic|Digest • AuthUserFile /path/to/file/containing/user/credentials • AuthName “MyAuthExampleName” • restrictions • Example: • AuthType Basic • AuthName “Rams Free Zone” • AuthUserFile /home/mklein/cs518passwd • <LIMIT GET POST> • Require valid-user • </LIMIT> htpasswd -c /home/mklein/cs518passwd mklein Default: crypt(), others: md5, sha, plain (BOOO!) See: man htpasswd http://mln-web.cs.odu.edu/~mklein/cs518/restricted

  3. Protect Files – the PHP Way • Sessions • session_start(); • associative array $_SESSION • test, e.g. • if(isset ($_SESSION[‘logged’]) && $_SESSION[‘logged’] == 1) { • echo “you are logged in”; • } else { • echo “you need to login!”; • } • NOTE: • can transport session from page to page • but session is destroyed when browser closed (session_destroy()) • server sided hence user is NOT able to modify session data • see example, ch12 (book) ch11 (sample code on website)

  4. Protect Files – the PHP Way • Cookies • setcookie(name, value, expiration); • name: used to retrieve cookie • value: value stored in cookie (username, last visit) • expiration: date when cookie will expire/be deleted(if not set, cookie is treated as session cookie – removed at browser restart) • setcookie(‘username’,”mklein”, time() + 60) // lasts 60s • setcookie(‘username’,”mklein”, 60) // 60s after midnight 1/1/1970 - destroy • associative array $_COOKIE • test, e.g. • if($_COOKIE[‘username’] ! =“”)) { • echo “your name is: $_COOKIE[‘username’]”; • } else { • echo “who are you?”; • } • NOTE: • persistent login, for example • client sided hence user IS able to modify cookie data

  5. File Upload with PHP • HTML form based • POST method • Content Type (enctype) attribute: multipart/form-data(and not application/x-www-form-urlencoded) • define MAX_FILE_SIZE [in B] in hidden filed, must precede: • input field type: file • its name is important! • Example: • <form enctype="multipart/form-data" action=“file_upload.php" method="POST"> • <input type="hidden" name="MAX_FILE_SIZE" value="30000" /> • Send this file: <input name=“mkfile" type="file" /> • <input type="submit" value="Send File" /> • </form>

  6. File Upload with PHP • associative array $_FILES • $_FILES[‘mkfile’][‘name’] – original name from client • $_FILES[‘mkfile’][‘type’] – mime type if provided • $_FILES[‘mkfile’][‘size’] – size in B • $_FILES[‘mkfile’][‘tmp_name’] – tmp file name on server • $_FILES[‘mkfile’][‘error’] – error code

  7. File Upload with PHP – Error Codes • UPLOAD_ERR_OK[0] • no error, file upload successful • UPLOAD_ERR_INI_SIZE [1] • uploaded file exceeds upload_max_filesize in php.ini • UPLOAD_ERR_FORM_SIZE [2] • uploaded file exceeds MAX_FILE_SIZE specified in HTML form • UPLOAD_ERR_PARTIAL [3] • file was only partially uploaded • UPLOAD_ERR_NO_FILE [4] • no file uploaded • UPLOAD_ERR_NO_TMP_DIR [6] • missing temporary folder • UPLOAD_ERR_CANT_WRITE [7] • write file to disk failed • UPLOAD_ERR_EXTENSION[8] • PHP extension stopped the file upload

  8. File Upload with PHP Example: <?php$uploaddir = '/home/mklein/public_html/uploads/';$uploadfile = $uploaddir . basename($_FILES[‘mkfile']['name']);if (move_uploaded_file($_FILES[‘mkfile']['tmp_name'], $uploadfile)) {    echo "File is valid, and was successfully uploaded.\n";} else {    echo "Possible file upload attack!\n";}echo 'Here is some more debugging info:';print_r($_FILES);?>

  9. Upload Multiple Files with PHP • similar to single file upload • use array of file names • Example: • <form enctype="multipart/form-data" action=“file_upload.php" method="POST"> • Send these files:<br> • <input name=“mkfile[]" type="file" /> //file1.txt; 13KB • <input name=“mkfile[]" type="file" /> //file2.png; 42KB • <input name=“mkfile[]" type="file" /> //file3.pdf; 113KB • <input type="submit" value="Send Files" /> • </form> • $_FILES[‘mkfile’][‘name’][0] eq file1.txt • $_FILES[‘mkfile’][‘name’][1] eq file2.png • $_FILES[‘mkfile’][‘name’][2] eq file3.pdf • $_FILES[‘mkfile’][‘size’][0] eq 13KB • $_FILES[‘mkfile’][‘size’][1] eq 42KB • $_FILES[‘mkfile’][‘size’][2] eq 113KB

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