get_meta_tags

This regex gets meta tags independent of sequence by capturing inside a lookahead.
Further uses the branch reset feature for different quote styles of values.
The pattern can be tested here: https://regex101.com/r/oE4oU9/1

<?PHP

function getMetaTags($str)
{
  $pattern = '
  ~<\s*meta\s

  # using lookahead to capture type to $1
    (?=[^>]*?
    \b(?:name|property|http-equiv)\s*=\s*
    (?|"\s*([^"]*?)\s*"|\'\s*([^\']*?)\s*\'|
    ([^"\'>]*?)(?=\s*/?\s*>|\s\w+\s*=))
  )

  # capture content to $2
  [^>]*?\bcontent\s*=\s*
    (?|"\s*([^"]*?)\s*"|\'\s*([^\']*?)\s*\'|
    ([^"\'>]*?)(?=\s*/?\s*>|\s\w+\s*=))
  [^>]*>

  ~ix';
  
  if(preg_match_all($pattern, $str, $out))
    return array_combine($out[1], $out[2]);
  return array();
}

// usage
$meta_tags = getMetaTags($str);

?>

I personally experienced less issues using the DOM functions than regular expressions while trying to fetch meta tags and not using get_meta_tags function (in order to get http-equiv meta tags too).

<?php

$doc = new DOMDocument();
$doc->loadHTML($html);

$xpath = new DOMXPath($doc);

$nodes = $xpath->query('//head/meta');

foreach($nodes as $node) {
    [...]
}

?>

Be aware that the function looks for the metatags in the whole page. If one of the meta is commented in your code for some reason, it will still be grabed.

in response to
jp at webgraphe dot com

this function grabs meta tags, not http headers

if you need the headers

<?php

$fp = fopen('http://example.org/somepage.html', 'r');

// the variable $http_response_header magically appears
print_r($http_response_header);

// or
$meta_data = stream_get_meta_data($fp);
print_r($meta_data);

?>

An Important Note about META tags and this function :  if your META tag contains newline "\n"  characters, get_meta_tags() will return a NULL value for that name property.  Removing the newlines from the source META tag corrects the problem.

Based on Michael Knapp's code, and adding some regex, here's a function that will get all meta tags and the title based on a URL. If there's an error, it will return false. Using the function getUrlContents(), also included, it takes care of META REFRESH re-directions, following up to the specified number of redirections. Please note that the regular expressions included were split into strings because php.net was complaining about the line being to long ;)

<?php
function getUrlData($url)
{
    $result = false;
    
    $contents = getUrlContents($url);

    if (isset($contents) && is_string($contents))
    {
        $title = null;
        $metaTags = null;
        
        preg_match('/<title>([^>]*)<\/title>/si', $contents, $match );

        if (isset($match) && is_array($match) && count($match) > 0)
        {
            $title = strip_tags($match[1]);
        }
        
        preg_match_all('/<[\s]*meta[\s]*name="?' . '([^>"]*)"?[\s]*' . 'content="?([^>"]*)"?[\s]*[\/]?[\s]*>/si', $contents, $match);
        
        if (isset($match) && is_array($match) && count($match) == 3)
        {
            $originals = $match[0];
            $names = $match[1];
            $values = $match[2];
            
            if (count($originals) == count($names) && count($names) == count($values))
            {
                $metaTags = array();
                
                for ($i=0, $limiti=count($names); $i < $limiti; $i++)
                {
                    $metaTags[$names[$i]] = array (
                        'html' => htmlentities($originals[$i]),
                        'value' => $values[$i]
                    );
                }
            }
        }
        
        $result = array (
            'title' => $title,
            'metaTags' => $metaTags
        );
    }
    
    return $result;
}

function getUrlContents($url, $maximumRedirections = null, $currentRedirection = 0)
{
    $result = false;
    
    $contents = @file_get_contents($url);
    
    // Check if we need to go somewhere else
    
    if (isset($contents) && is_string($contents))
    {
        preg_match_all('/<[\s]*meta[\s]*http-equiv="?REFRESH"?' . '[\s]*content="?[0-9]*;[\s]*URL[\s]*=[\s]*([^>"]*)"?' . '[\s]*[\/]?[\s]*>/si', $contents, $match);
        
        if (isset($match) && is_array($match) && count($match) == 2 && count($match[1]) == 1)
        {
            if (!isset($maximumRedirections) || $currentRedirection < $maximumRedirections)
            {
                return getUrlContents($match[1][0], $maximumRedirections, ++$currentRedirection);
            }
            
            $result = false;
        }
        else
        {
            $result = $contents;
        }
    }
    
    return $contents;
}
?>

Here's an example of its usage. Check that the included URL has a META REFRESH redirection:

<?php
$result = getUrlData('http://www.marianoiglesias.com.ar/');

echo '<pre>'; print_r($result); echo '</pre>';

?>

For the above code the output would be:

<?php
Array
(
    [title] => Mariano Iglesias: El Eternauta    
    [metaTags] => Array
        (
            [description] => Array
                (
                    [html] => <meta name="description" content="Java, PHP, and some other technological mumble jumble. Also, some real-life stuff as well." />
                    [value] => Java, PHP, and some other technological mumble jumble. Also, some real-life stuff as well.
                )

            [DC.title] => Array
                (
                    [html] => <meta name="DC.title" content="Mariano Iglesias - Weblog" />
                    [value] => Mariano Iglesias - Weblog
                )

            [ICBM] => Array
                (
                    [html] => <meta name="ICBM" content="-34.6017, -58.3956" />
                    [value] => -34.6017, -58.3956
                )

            [geo.position] => Array
                (
                    [html] => <meta name="geo.position" content="-34.6017;-58.3956" />
                    [value] => -34.6017;-58.3956
                )

            [geo.region] => Array
                (
                    [html] => <meta name="geo.region" content="AR-BA">
                    [value] => AR-BA
                )

            [geo.placename] => Array
                (
                    [html] => <meta name="geo.placename" content="Buenos Aires">
                    [value] => Buenos Aires
                )

        )

)
?>

New version based on mariano at cricava dot com's work with:
1) Support for Meta properties (like Facebook's og tags).
2) Support for Unicode (UTF-8) encoded Meta lines.
3) An option not to convert htmlentities - if you plan to actually use the results and not just display them.

function getUrlData($url, $raw=false) // $raw - enable for raw display
{
    $result = false;
   
    $contents = getUrlContents($url);

    if (isset($contents) && is_string($contents))
    {
        $title = null;
        $metaTags = null;
        $metaProperties = null;
       
        preg_match('/<title>([^>]*)<\/title>/si', $contents, $match );

        if (isset($match) && is_array($match) && count($match) > 0)
        {
            $title = strip_tags($match[1]);
        }
       
        preg_match_all('/<[\s]*meta[\s]*(name|property)="?' . '([^>"]*)"?[\s]*' . 'content="?([^>"]*)"?[\s]*[\/]?[\s]*>/si', $contents, $match);
       
        if (isset($match) && is_array($match) && count($match) == 4)
        {
            $originals = $match[0];
            $names = $match[2];
            $values = $match[3];
           
            if (count($originals) == count($names) && count($names) == count($values))
            {
                $metaTags = array();
                $metaProperties = $metaTags;
                if ($raw) {
                    if (version_compare(PHP_VERSION, '5.4.0') == -1)
                         $flags = ENT_COMPAT;
                    else
                         $flags = ENT_COMPAT | ENT_HTML401;
                }
               
                for ($i=0, $limiti=count($names); $i < $limiti; $i++)
                {
                    if ($match[1][$i] == 'name')
                         $meta_type = 'metaTags';
                    else
                         $meta_type = 'metaProperties';
                    if ($raw)
                        ${$meta_type}[$names[$i]] = array (
                            'html' => htmlentities($originals[$i], $flags, 'UTF-8'),
                            'value' => $values[$i]
                        );
                    else
                        ${$meta_type}[$names[$i]] = array (
                            'html' => $originals[$i],
                            'value' => $values[$i]
                        );
                }
            }
        }
       
        $result = array (
            'title' => $title,
            'metaTags' => $metaTags,
            'metaProperties' => $metaProperties,
        );
    }
   
    return $result;
}

function getUrlContents($url, $maximumRedirections = null, $currentRedirection = 0)
{
    $result = false;
   
    $contents = @file_get_contents($url);
   
    // Check if we need to go somewhere else
   
    if (isset($contents) && is_string($contents))
    {
        preg_match_all('/<[\s]*meta[\s]*http-equiv="?REFRESH"?' . '[\s]*content="?[0-9]*;[\s]*URL[\s]*=[\s]*([^>"]*)"?' . '[\s]*[\/]?[\s]*>/si', $contents, $match);
       
        if (isset($match) && is_array($match) && count($match) == 2 && count($match[1]) == 1)
        {
            if (!isset($maximumRedirections) || $currentRedirection < $maximumRedirections)
            {
                return getUrlContents($match[1][0], $maximumRedirections, ++$currentRedirection);
            }
           
            $result = false;
        }
        else
        {
            $result = $contents;
        }
    }
   
    return $contents;
}
?>

<?php
$result = getUrlData('http://whatever...', true);

echo '<pre>'; print_r($result, true); echo '</pre>';

?>

Output example:

<?php
Array
(
    [title] => The requested page's title
    [metaTags] => Array
        (
            [description] => Array
                (
                    [html] => <meta name="description" content="Something..." />
                    [value] => Something...
                )
        )
    [metaProperties] => Array
        (
            [og:type] => Array
                (
                    [html] => <meta property="og:type" content="article"/>/>
                    [value] => article
                )
        )
)
?>

This is a slight amendment to jimmyxx at gmail dot com function

I tried using the regex displayed in his code, and php threw up a couple of errors

Below is the correct regular expression that works
(Please note that I had to split the regex into strings because php.net was complaining about the line being to long)
<?php
preg_match_all(
   "|<meta[^>]+name=\"([^\"]*)\"[^>]" . "+content=\"([^\"]*)\"[^>]+>|i",
   $html, $out,PREG_PATTERN_ORDER);
?>

The problem was due to the quotes being incorrectly escaped.
I hope this helps anyone who has been having problems with his code

If the URL is doing a redirection using the headers (like you would do with PHP function header("Location: URL");), the page has no content (in general). It appears get_meta_tags() doesn't catch that kind of redirection (like cURL would do) and it lead me to a timeout of my script.

I experienced this in a spider I wrote in order to feed my database of all available pages on my site and one link was linking to a page that simply has the following code:

<?php
  header("Location: sections.php?section=home");
  exit();
?>

That made my script hang for a moment and apparently, get_meta_tags() wasn't even able to return me an error.

JP.