Check for valid gravatar (PHP)

Question

I'm pretty new to PHP, so if you have any thoughts or suggestions to point me in the right direction, I'd be grateful.

Trying to make a simple function to check if a user's email address translates into a valid Gravatar Image, but it seems gravatar.com has changed their headers.

Using get_headers('[email protected]') returns a 200 instead of 302.

Here are the headers from a bad gravatar image, none of which seem to be able to help because they are identical to a valid gravatar image:

array(13) {
  [0]=>
  string(15) "HTTP/1.1 200 OK"
  [1]=>
  string(13) "Server: nginx"
  [2]=>
  string(35) "Date: Sun, 26 Jul 2009 20:22:07 GMT"
  [3]=>
  string(24) "Content-Type: image/jpeg"
  [4]=>
  string(17) "Connection: close"
  [5]=>
  string(44) "Last-Modified: Sun, 26 Jul 2009 19:47:12 GMT"
  [6]=>
  string(76) "Content-Disposition: inline; filename="5ed352b75af7175464e354f6651c6e9e.jpg""
  [7]=>
  string(20) "Content-Length: 3875"
  [8]=>
  string(32) "X-Varnish: 3883194649 3880834433"
  [9]=>
  string(16) "Via: 1.1 varnish"
  [10]=>
  string(38) "Expires: Sun, 26 Jul 2009 20:27:07 GMT"
  [11]=>
  string(26) "Cache-Control: max-age=300"
  [12]=>
  string(16) "Source-Age: 1322"
}

p.s. I am aware of the '&d' parameter, but it will not serve my purpose. :)

EDIT:

Use '?d' instead of '&d'. Must be a gravatar.com 'thang.

Answer 1

Gravatar have added an option to the 'd' parameter, meaning that if you pass in d=404, you get a 404 page (instead of some 302 redirect to a default picture) if there's no picture, rather than having to use heuristics.

Answer 2

NOTE: at the time of writing, this was the only option. However, some later time ?d=404 was added, making Andrew's answer much cleaner.

---

Though you said you know about the d parameter, do you know it actually returns a redirect header when applicable? So, the following yields 302 Found because the avatar does not exist:

http://www.gravatar.com/avatar/3b3be63a4c2a439b013787725dfce802?d=http%3A%2F%2Fwww.google.com%2Fimages%2Flogo.gif

HTTP/1.1 302 Found  
...  
Last-Modified: Wed, 11 Jan 1984 08:00:00 GMT  
Location: http://www.google.com/images/logo.gif  
Content-Length: 0  
...  
Expires: Sun, 26 Jul 2009 23:18:33 GMT  
Cache-Control: max-age=300

Seems to me that all you need to do is add that d parameter and check the HTTP result code then.

Answer 3

I suggest you try the php gravatar class by Lucas Araújo.

/**
*  Class Gravatar
*
* From Gravatar Help:
*        "A gravatar is a dynamic image resource that is requested from our server. The request
*        URL is presented here, broken into its segments."
* Source:
*    http://site.gravatar.com/site/implement
*
* Usage:
* <code>
*        $email = "[email protected]";
*        $default = "http://www.yourhost.com/default_image.jpg";    // Optional
*        $gravatar = new Gravatar($email, $default);
*        $gravatar->size = 80;
*        $gravatar->rating = "G";
*        $gravatar->border = "FF0000";
*
*        echo $gravatar; // Or echo $gravatar->toHTML();
* </code>
*
*    Class Page: http://www.phpclasses.org/browse/package/4227.html
*
* @author Lucas Araújo <[email protected]>
* @version 1.0
* @package Gravatar
*/
class Gravatar
{
    /**
     *    Gravatar's url
     */
    const GRAVATAR_URL = "http://www.gravatar.com/avatar.php";

    /**
     *    Ratings available
     */
    private $GRAVATAR_RATING = array("G", "PG", "R", "X");

    /**
     *    Query string. key/value
     */
    protected $properties = array(
        "gravatar_id"    => NULL,
        "default"        => NULL,
        "size"            => 80,        // The default value
        "rating"        => NULL,
        "border"        => NULL,
    );

    /**
     *    E-mail. This will be converted to md5($email)
     */
    protected $email = "";

    /**
     *    Extra attributes to the IMG tag like ALT, CLASS, STYLE...
     */
    protected $extra = "";

    /**
     *    
     */
    public function __construct($email=NULL, $default=NULL) {
        $this->setEmail($email);
        $this->setDefault($default);
    }

    /**
     *    
     */
    public function setEmail($email) {
        if ($this->isValidEmail($email)) {
            $this->email = $email;
            $this->properties['gravatar_id'] = md5(strtolower($this->email));
            return true;
        }
        return false;
    }

    /**
     *    
     */
    public function setDefault($default) {
        $this->properties['default'] = $default;
    }

    /**
     *    
     */
    public function setRating($rating) {
        if (in_array($rating, $this->GRAVATAR_RATING)) {
            $this->properties['rating'] = $rating;
            return true;
        }
        return false;
    }

    /**
     *    
     */
    public function setSize($size) {
        $size = (int) $size;
        if ($size <= 0)
            $size = NULL;        // Use the default size
        $this->properties['size'] = $size;
    }

    /**
     *    
     */
    public function setExtra($extra) {
        $this->extra = $extra;
    }

    /**
     *    
     */
    public function isValidEmail($email) {
        // Source: http://www.zend.com/zend/spotlight/ev12apr.php
        return eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email);
    }

    /**
     *    Object property overloading
     */
    public function __get($var) { return @$this->properties[$var]; }

    /**
     *    Object property overloading
     */
    public function __set($var, $value) {
        switch($var) {
            case "email":    return $this->setEmail($value);
            case "rating":    return $this->setRating($value);
            case "default":    return $this->setDefault($value);
            case "size":    return $this->setSize($value);
            // Cannot set gravatar_id
            case "gravatar_id": return;
        }
        return @$this->properties[$var] = $value;
    }

    /**
     *    Object property overloading
     */
    public function __isset($var) { return isset($this->properties[$var]); }

    /**
     *    Object property overloading
     */
    public function __unset($var) { return @$this->properties[$var] == NULL; }

    /**
     *    Get source
     */
    public function getSrc() {
        $url = self::GRAVATAR_URL ."?";
        $first = true;
        foreach($this->properties as $key => $value) {
            if (isset($value)) {
                if (!$first)
                    $url .= "&";
                $url .= $key."=".urlencode($value);
                $first = false;
            }
        }
        return $url;    
    }

    /**
     *    toHTML
     */
    public function toHTML() {
        return     '<img src="'. $this->getSrc() .'"'
                .(!isset($this->size) ? "" : ' width="'.$this->size.'" height="'.$this->size.'"')
                .$this->extra
                .' />';    
    }

    /**
     *    toString
     */
    public function __toString() { return $this->toHTML(); }
} 

and this is how you'd use it:

include 'gravatar.php';
$eMail = '[email protected]';
$defImg = 'http://www.example.com/images/myphoto.jpg';
$avatar = new Gravatar($eMail, $defImg);
$avatar->setSize(90);
$avatar->setRating('G');
$avatar->setExtra('alt="my gravatar"');

<p>
<?php echo $avatar->toHTML(); ?>
</p>

Answer 4

add the "default" parameter to the image url when checking for a gravatar, this will provide a 302 redirect if the image is not found.

$grav_url = 'http://www.gravatar.com/avatar/'.md5(mb_strtolower($email)).'?default=http://www.mysite.com/null.jpg&size=310';

the null image could then return a 404 if you want it to :)