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LAMP, OAuth, Software design, Twitter, Web

Twitter OAuth with PHP and cURL multi

09.22.10 | Comment?

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I am maintaining a website that aggregate a large number of Twitter accounts’ tweets. For this purpose we’ve been given one of the accounts with the high API request rate limit – usually it is possible to call the Twitter API’s 150 times every hour. We have a rate limit of 20.000 hourly requests and we use most of them to keep up a near real time picture of the activity of the user base.

Recently Twitter disabled regular basic HTTP authentication supporting only OAuth – which generally is a good thing, In this case we simply read the RSS-version of the user_timeline and OAuth seems overkill for reading a simple public time line.¬†Aaaanyways – we are using PHP with cURL multi and OAuth introduces a bit of extra code. Sure – there are plenty of OAuth API’s and OAuth API’s for Twitter out there, but the specific combination of PHP cURL multi and GET’ing user_timelines required a combination of Google’ing and a bit of guesswork.

Preparations

– First¬†Register your application with Twitter – You’ll need a couple of tokens and secrets from your app-page and from the specific token page.
– If you need to make more than 150 requests per hour, apply for¬†whitelisting here. ¬†It’ll take a while for Twitter to process your request.
– Make sure you have cURL for PHP installed

Specifically preparing the GET connections for cURL presented a challenge – this piece of code did the trick for us:

<?php
// $url_array is an array of Twitter RSS-feed URL's that we need to read
$mh = curl_multi_init();
foreach($url_array as $i => $item) {
	// Keys and secrets from http://dev.twitter.com/apps/
	$consumer_secret = '<get your own from http://dev.twitter.com/apps/_your_app_id_/>';
	$token_secret = '<get your own from http://dev.twitter.com/apps/_your_app_id_/my_token>';

	// Build ud an array of OAuth parameters
	$params = Array();
	$params['oauth_consumer_key'] = '<get your own from http://dev.twitter.com/apps/_your_app_id_/>';
	$params['oauth_token'] = '<get your own from http://dev.twitter.com/apps/_your_app_id_/my_token>';
	$params['oauth_signature_method'] = 'HMAC-SHA1';
	$thetime = time();
	$params['oauth_timestamp'] = $thetime;
	$params['oauth_nonce'] = SHA1($thetime);
	$params['oauth_version'] = '1.0';

	// Sort the array alphabetically
	ksort($params);

	// Build the paramter string for the GET request
	$concatenatedParams = '';
	foreach($params as $k => $v)
	{
	  $k = urlencode($k);
	  $v = urlencode($v);
	  $concatenatedParams .= "{$k}={$v}&";
	}
	$unencodedParams = substr($concatenatedParams,0,-1);
	// URL-encode the parameters for signature use
	$concatenatedParams = urlencode(substr($concatenatedParams,0,-1));
	$signatureBaseString = "GET&".urlencode($item['url'])."&".$concatenatedParams;

	$params['oauth_signature'] = base64_encode( hash_hmac('sha1', $signatureBaseString, $consumer_secret."&".$token_secret, true) );

	// Initiate a new cURL connection and set up it's URL
	$conn[$i] = curl_init();
	curl_setopt($conn[$i], CURLOPT_URL, $item['url'] . '?' . $unencodedParams);
	curl_setopt($conn[$i], CURLINFO_HEADER_OUT, 1);

	// Build the HTTP header for the request
	$curlheader = Array();
	$curlheader[]='Content-Type: application/x-www-form-urlencoded';
	$curlheader[] = 'Authorization: OAuth';
	foreach($params as $ky=>$va) {
		$curlheader[] = "$ky=$va,\n";
	}

	// Initiate a new cURL connection and assign URL + HTTP header to it
	$conn[$i] = curl_init($item['url']);
	curl_setopt($conn[$i], CURLOPT_HTTPHEADER, $curlheader);
	curl_setopt($conn[$i], CURLOPT_HTTPGET, 1);

	// Add the connection to the cURL multi handle
	curl_multi_add_handle ($mh,$conn[$i]);
}

// Now execute curl_multi_exec on the $mh handle
This can no doubt be improved and secured in many ways, but since this specific example runs from as a cron-job/a PHP CLI Рnot on a server that replies to  inbound connections Рthe keys are not secured any further in this implementation.

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