Useful PHP Techniques

CORS.php

/**
 *  An example CORS-compliant method.  It will allow any GET, POST, or OPTIONS requests from any
 *  origin.
 *
 *  In a production environment, you probably want to be more restrictive, but this gives you
 *  the general idea of what is involved.  For the nitty-gritty low-down, read:
 *
 *  - https://developer.mozilla.org/en/HTTP_access_control
 *  - http://www.w3.org/TR/cors/
 *
 */
function cors() {

    // Allow from any origin
    if (isset($_SERVER['HTTP_ORIGIN'])) {
        header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
        header('Access-Control-Allow-Credentials: true');
        header('Access-Control-Max-Age: 86400');    // cache for 1 day
    }

    // Access-Control headers are received during OPTIONS requests
    if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
            header("Access-Control-Allow-Methods: GET, POST, OPTIONS");         

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
            header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");

        exit(0);
    }

    echo "You have CORS!";
}

CsvProcessor.php

/**
 *  This demonstrates a handy way to process a CSV file.
 *  
 *  - The first line of the CSV file is assumed to be a header line, which defines the name and order of the fields
 *  - Each subsequent line of the file will be turned into an array
 *  - Lines that are improperly formatted (ie: a different number of items than the header) are ignored.
 *  - Each line of data is converted into an associative array.  The name of each field is taken from the header line.
 *  - The names of the fields are significant, but the order is not.
 */
function processCsvFile($input, $callable) {
  $columns = fgetcsv($input);
  if ($columns === false)
    return;
  
  while( ($line = fgetcsv($input)) !== false ) {
    $line = @array_combine($columns, $line);
    if ($line !== false)
      $callable($line);
  }
}

// You could consume STDIN as a CSV file and output each line as an array like so.
 processCsvFile(STDIN, function ($ar) { print_r($ar); });

TempUrlController.php

class Docreader extends CI_Controller {
    private $secret = 'aADFj98333(*&9jfa;';

    /**
     *  This controller will share documents, but only with people who hold a temporary URL that 
     *  grants them access.  The format of the url is:
     *
     *      http://mysite.com/docreader/templink/docid/expiration/signature
     *  Example:
     *      http://mysite.com/docreader/templink/12345/1332995495/44377d14be1f0ae512ac518f250b8b39
     *
     *  @param string $docid The id of the document to server (very application-specific)
     *  @param int $expiration When the templink will expire
     *  @param string $signature The HMAC-MD5 signature
     */
     public function templink($docid, $expiration, $signature) {
        $computedSignature = $this->generateSignature($docid, $expiration);

        if ($expiration <= time() && $signature == $computedSignature) {
            // serve the document
        } else {
            // send an error
        }
     }

     /**
      * The signature is simply an HMAC of $docid '/' $expiration
      *
      * @param string $docid The identifier you are using for the serveable document
      * @param int $expiration The unix time at which the link will expire
      */
     private function generateSignature($docid, $expiration) {
        return hash_hmac("md5", "$docid/$expiration", $this->secret);
     }
}