friendica-addons/statusnet/library/OAuth1.php

<?php
// vim: foldmethod=marker

/* Generic exception class
 */
if (!class_exists('OAuthException')) {
	class OAuthException extends Exception {
		// pass
	}

	class OAuthConsumer {
	  public $key;
	  public $secret;

	  function __construct($key, $secret, $callback_url=NULL) {
		$this->key = $key;
		$this->secret = $secret;
		$this->callback_url = $callback_url;
	  }

	  function __toString() {
		return "OAuthConsumer[key=$this->key,secret=$this->secret]";
	  }
	}

	class OAuthToken {
	  // access tokens and request tokens
	  public $key;
	  public $secret;

	  public $expires;
	  public $scope;
	  public $uid;

	  /**
	   * key = the token
	   * secret = the token secret
	   */
	  function __construct($key, $secret) {
		$this->key = $key;
		$this->secret = $secret;
	  }

	  /**
	   * generates the basic string serialization of a token that a server
	   * would respond to request_token and access_token calls with
	   */
	  function to_string() {
		return "oauth_token=" .
			   OAuthUtil::urlencode_rfc3986($this->key) .
			   "&oauth_token_secret=" .
			   OAuthUtil::urlencode_rfc3986($this->secret);
	  }

	  function __toString() {
		return $this->to_string();
	  }
	}

	/**
	 * A class for implementing a Signature Method
	 * See section 9 ("Signing Requests") in the spec
	 */
	abstract class OAuthSignatureMethod {
	  /**
	   * Needs to return the name of the Signature Method (ie HMAC-SHA1)
	   * @return string
	   */
	  abstract public function get_name();

	  /**
	   * Build up the signature
	   * NOTE: The output of this function MUST NOT be urlencoded.
	   * the encoding is handled in OAuthRequest when the final
	   * request is serialized
	   * @param OAuthRequest $request
	   * @param OAuthConsumer $consumer
	   * @param OAuthToken $token
	   * @return string
	   */
	  abstract public function build_signature($request, $consumer, $token);

	  /**
	   * Verifies that a given signature is correct
	   * @param OAuthRequest $request
	   * @param OAuthConsumer $consumer
	   * @param OAuthToken $token
	   * @param string $signature
	   * @return bool
	   */
	  public function check_signature($request, $consumer, $token, $signature) {
		$built = $this->build_signature($request, $consumer, $token);
		//echo "<pre>"; var_dump($signature, $built, ($built == $signature)); killme();
		return ($built == $signature);
	  }
	}

	/**
	 * The HMAC-SHA1 signature method uses the HMAC-SHA1 signature algorithm as defined in [RFC2104]
	 * where the Signature Base String is the text and the key is the concatenated values (each first
	 * encoded per Parameter Encoding) of the Consumer Secret and Token Secret, separated by an '&'
	 * character (ASCII code 38) even if empty.
	 *   - Chapter 9.2 ("HMAC-SHA1")
	 */
	class OAuthSignatureMethod_HMAC_SHA1 extends OAuthSignatureMethod {
	  function get_name() {
		return "HMAC-SHA1";
	  }

	  public function build_signature($request, $consumer, $token) {
		$base_string = $request->get_signature_base_string();
		$request->base_string = $base_string;

		$key_parts = array(
		  $consumer->secret,
		  ($token) ? $token->secret : ""
		);

		$key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
		$key = implode('&', $key_parts);


		$r = base64_encode(hash_hmac('sha1', $base_string, $key, true));
		return $r;
	  }
	}

	/**
	 * The PLAINTEXT method does not provide any security protection and SHOULD only be used
	 * over a secure channel such as HTTPS. It does not use the Signature Base String.
	 *   - Chapter 9.4 ("PLAINTEXT")
	 */
	class OAuthSignatureMethod_PLAINTEXT extends OAuthSignatureMethod {
	  public function get_name() {
		return "PLAINTEXT";
	  }

	  /**
	   * oauth_signature is set to the concatenated encoded values of the Consumer Secret and
	   * Token Secret, separated by a '&' character (ASCII code 38), even if either secret is
	   * empty. The result MUST be encoded again.
	   *   - Chapter 9.4.1 ("Generating Signatures")
	   *
	   * Please note that the second encoding MUST NOT happen in the SignatureMethod, as
	   * OAuthRequest handles this!
	   */
	  public function build_signature($request, $consumer, $token) {
		$key_parts = array(
		  $consumer->secret,
		  ($token) ? $token->secret : ""
		);

		$key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
		$key = implode('&', $key_parts);
		$request->base_string = $key;

		return $key;
	  }
	}

	/**
	 * The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature algorithm as defined in
	 * [RFC3447] section 8.2 (more simply known as PKCS#1), using SHA-1 as the hash function for
	 * EMSA-PKCS1-v1_5. It is assumed that the Consumer has provided its RSA public key in a
	 * verified way to the Service Provider, in a manner which is beyond the scope of this
	 * specification.
	 *   - Chapter 9.3 ("RSA-SHA1")
	 */
	abstract class OAuthSignatureMethod_RSA_SHA1 extends OAuthSignatureMethod {
	  public function get_name() {
		return "RSA-SHA1";
	  }

	  // Up to the SP to implement this lookup of keys. Possible ideas are:
	  // (1) do a lookup in a table of trusted certs keyed off of consumer
	  // (2) fetch via http using a url provided by the requester
	  // (3) some sort of specific discovery code based on request
	  //
	  // Either way should return a string representation of the certificate
	  protected abstract function fetch_public_cert(&$request);

	  // Up to the SP to implement this lookup of keys. Possible ideas are:
	  // (1) do a lookup in a table of trusted certs keyed off of consumer
	  //
	  // Either way should return a string representation of the certificate
	  protected abstract function fetch_private_cert(&$request);

	  public function build_signature($request, $consumer, $token) {
		$base_string = $request->get_signature_base_string();
		$request->base_string = $base_string;

		// Fetch the private key cert based on the request
		$cert = $this->fetch_private_cert($request);

		// Pull the private key ID from the certificate
		$privatekeyid = openssl_get_privatekey($cert);

		// Sign using the key
		$ok = openssl_sign($base_string, $signature, $privatekeyid);

		// Release the key resource
		openssl_free_key($privatekeyid);

		return base64_encode($signature);
	  }

	  public function check_signature($request, $consumer, $token, $signature) {
		$decoded_sig = base64_decode($signature);

		$base_string = $request->get_signature_base_string();

		// Fetch the public key cert based on the request
		$cert = $this->fetch_public_cert($request);

		// Pull the public key ID from the certificate
		$publickeyid = openssl_get_publickey($cert);

		// Check the computed signature against the one passed in the query
		$ok = openssl_verify($base_string, $decoded_sig, $publickeyid);

		// Release the key resource
		openssl_free_key($publickeyid);

		return $ok == 1;
	  }
	}

	class OAuthRequest {
	  private $parameters;
	  private $http_method;
	  private $http_url;
	  // for debug purposes
	  public $base_string;
	  public static $version = '1.0';
	  public static $POST_INPUT = 'php://input';

	  function __construct($http_method, $http_url, $parameters=NULL) {
		@$parameters or $parameters = array();
		$parameters = array_merge( OAuthUtil::parse_parameters(parse_url($http_url, PHP_URL_QUERY)), $parameters);
		$this->parameters = $parameters;
		$this->http_method = $http_method;
		$this->http_url = $http_url;
	  }


	  /**
	   * attempt to build up a request from what was passed to the server
	   */
	  public static function from_request($http_method=NULL, $http_url=NULL, $parameters=NULL) {
		$scheme = (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on")
				  ? 'http'
				  : 'https';
		@$http_url or $http_url = $scheme .
								  '://' . $_SERVER['HTTP_HOST'] .
								  ':' .
								  $_SERVER['SERVER_PORT'] .
								  $_SERVER['REQUEST_URI'];
		@$http_method or $http_method = $_SERVER['REQUEST_METHOD'];

		// We weren't handed any parameters, so let's find the ones relevant to
		// this request.
		// If you run XML-RPC or similar you should use this to provide your own
		// parsed parameter-list
		if (!$parameters) {
		  // Find request headers
		  $request_headers = OAuthUtil::get_headers();

		  // Parse the query-string to find GET parameters
		  $parameters = OAuthUtil::parse_parameters($_SERVER['QUERY_STRING']);

		  // It's a POST request of the proper content-type, so parse POST
		  // parameters and add those overriding any duplicates from GET
		  if ($http_method == "POST"
			  && @strstr($request_headers["Content-Type"],
						 "application/x-www-form-urlencoded")
			  ) {
			$post_data = OAuthUtil::parse_parameters(
			  file_get_contents(self::$POST_INPUT)
			);
			$parameters = array_merge($parameters, $post_data);
		  }

		  // We have a Authorization-header with OAuth data. Parse the header
		  // and add those overriding any duplicates from GET or POST
		  if (@substr($request_headers['Authorization'], 0, 6) == "OAuth ") {
			$header_parameters = OAuthUtil::split_header(
			  $request_headers['Authorization']
			);
			$parameters = array_merge($parameters, $header_parameters);
		  }

		}
		// fix for friendica redirect system

		$http_url =  substr($http_url, 0, strpos($http_url,$parameters['pagename'])+strlen($parameters['pagename']));
		unset( $parameters['pagename'] );

		//echo "<pre>".__function__."\n"; var_dump($http_method, $http_url, $parameters, $_SERVER['REQUEST_URI']); killme();
		return new OAuthRequest($http_method, $http_url, $parameters);
	  }

	  /**
	   * pretty much a helper function to set up the request
	   */
	  public static function from_consumer_and_token($consumer, $token, $http_method, $http_url, $parameters=NULL) {
		@$parameters or $parameters = array();
		$defaults = array("oauth_version" => OAuthRequest::$version,
						  "oauth_nonce" => OAuthRequest::generate_nonce(),
						  "oauth_timestamp" => OAuthRequest::generate_timestamp(),
						  "oauth_consumer_key" => $consumer->key);
		if ($token)
		  $defaults['oauth_token'] = $token->key;

		$parameters = array_merge($defaults, $parameters);

		return new OAuthRequest($http_method, $http_url, $parameters);
	  }

	  public function set_parameter($name, $value, $allow_duplicates = true) {
		if ($allow_duplicates && isset($this->parameters[$name])) {
		  // We have already added parameter(s) with this name, so add to the list
		  if (is_scalar($this->parameters[$name])) {
			// This is the first duplicate, so transform scalar (string)
			// into an array so we can add the duplicates
			$this->parameters[$name] = array($this->parameters[$name]);
		  }

		  $this->parameters[$name][] = $value;
		} else {
		  $this->parameters[$name] = $value;
		}
	  }

	  public function get_parameter($name) {
		return isset($this->parameters[$name]) ? $this->parameters[$name] : null;
	  }

	  public function get_parameters() {
		return $this->parameters;
	  }

	  public function unset_parameter($name) {
		unset($this->parameters[$name]);
	  }

	  /**
	   * The request parameters, sorted and concatenated into a normalized string.
	   * @return string
	   */
	  public function get_signable_parameters() {
		// Grab all parameters
		$params = $this->parameters;

		// Remove oauth_signature if present
		// Ref: Spec: 9.1.1 ("The oauth_signature parameter MUST be excluded.")
		if (isset($params['oauth_signature'])) {
		  unset($params['oauth_signature']);
		}

		return OAuthUtil::build_http_query($params);
	  }

	  /**
	   * Returns the base string of this request
	   *
	   * The base string defined as the method, the url
	   * and the parameters (normalized), each urlencoded
	   * and the concated with &.
	   */
	  public function get_signature_base_string() {
		$parts = array(
		  $this->get_normalized_http_method(),
		  $this->get_normalized_http_url(),
		  $this->get_signable_parameters()
		);

		$parts = OAuthUtil::urlencode_rfc3986($parts);

		return implode('&', $parts);
	  }

	  /**
	   * just uppercases the http method
	   */
	  public function get_normalized_http_method() {
		return strtoupper($this->http_method);
	  }

	  /**
	   * parses the url and rebuilds it to be
	   * scheme://host/path
	   */
	  public function get_normalized_http_url() {
		$parts = parse_url($this->http_url);

		$port = @$parts['port'];
		$scheme = $parts['scheme'];
		$host = $parts['host'];
		$path = @$parts['path'];

		$port or $port = ($scheme == 'https') ? '443' : '80';

		if (($scheme == 'https' && $port != '443')
			|| ($scheme == 'http' && $port != '80')) {
		  $host = "$host:$port";
		}
		return "$scheme://$host$path";
	  }

	  /**
	   * builds a url usable for a GET request
	   */
	  public function to_url() {
		$post_data = $this->to_postdata();
		$out = $this->get_normalized_http_url();
		if ($post_data) {
		  $out .= '?'.$post_data;
		}
		return $out;
	  }

	  /**
	   * builds the data one would send in a POST request
	   */
	  public function to_postdata($raw = false) {
		if ($raw)
		  return($this->parameters);
		else
		  return OAuthUtil::build_http_query($this->parameters);
	  }

	  /**
	   * builds the Authorization: header
	   */
	  public function to_header($realm=null) {
		$first = true;
		if($realm) {
		  $out = 'Authorization: OAuth realm="' . OAuthUtil::urlencode_rfc3986($realm) . '"';
		  $first = false;
		} else
		  $out = 'Authorization: OAuth';

		$total = array();
		foreach ($this->parameters as $k => $v) {
		  if (substr($k, 0, 5) != "oauth") continue;
		  if (is_array($v)) {
			throw new OAuthException('Arrays not supported in headers');
		  }
		  $out .= ($first) ? ' ' : ',';
		  $out .= OAuthUtil::urlencode_rfc3986($k) .
				  '="' .
				  OAuthUtil::urlencode_rfc3986($v) .
				  '"';
		  $first = false;
		}
		return $out;
	  }

	  public function __toString() {
		return $this->to_url();
	  }


	  public function sign_request($signature_method, $consumer, $token) {
		$this->set_parameter(
		  "oauth_signature_method",
		  $signature_method->get_name(),
		  false
		);
		$signature = $this->build_signature($signature_method, $consumer, $token);
		$this->set_parameter("oauth_signature", $signature, false);
	  }

	  public function build_signature($signature_method, $consumer, $token) {
		$signature = $signature_method->build_signature($this, $consumer, $token);
		return $signature;
	  }

	  /**
	   * util function: current timestamp
	   */
	  private static function generate_timestamp() {
		return time();
	  }

	  /**
	   * util function: current nonce
	   */
	  private static function generate_nonce() {
		$mt = microtime();
		$rand = mt_rand();

		return md5($mt . $rand); // md5s look nicer than numbers
	  }
	}

	class OAuthServer {
	  protected $timestamp_threshold = 300; // in seconds, five minutes
	  protected $version = '1.0';             // hi blaine
	  protected $signature_methods = array();

	  protected $data_store;

	  function __construct($data_store) {
		$this->data_store = $data_store;
	  }

	  public function add_signature_method($signature_method) {
		$this->signature_methods[$signature_method->get_name()] =
		  $signature_method;
	  }

	  // high level functions

	  /**
	   * process a request_token request
	   * returns the request token on success
	   */
	  public function fetch_request_token(&$request) {
		$this->get_version($request);

		$consumer = $this->get_consumer($request);

		// no token required for the initial token request
		$token = NULL;

		$this->check_signature($request, $consumer, $token);

		// Rev A change
		$callback = $request->get_parameter('oauth_callback');
		$new_token = $this->data_store->new_request_token($consumer, $callback);

		return $new_token;
	  }

	  /**
	   * process an access_token request
	   * returns the access token on success
	   */
	  public function fetch_access_token(&$request) {
		$this->get_version($request);

		$consumer = $this->get_consumer($request);

		// requires authorized request token
		$token = $this->get_token($request, $consumer, "request");

		$this->check_signature($request, $consumer, $token);

		// Rev A change
		$verifier = $request->get_parameter('oauth_verifier');
		$new_token = $this->data_store->new_access_token($token, $consumer, $verifier);

		return $new_token;
	  }

	  /**
	   * verify an api call, checks all the parameters
	   */
	  public function verify_request(&$request) {
		$this->get_version($request);
		$consumer = $this->get_consumer($request);
		//echo __file__.__line__.__function__."<pre>"; var_dump($consumer); die();
		$token = $this->get_token($request, $consumer, "access");
		$this->check_signature($request, $consumer, $token);
		return array($consumer, $token);
	  }

	  // Internals from here
	  /**
	   * version 1
	   */
	  private function get_version(&$request) {
		$version = $request->get_parameter("oauth_version");
		if (!$version) {
		  // Service Providers MUST assume the protocol version to be 1.0 if this parameter is not present.
		  // Chapter 7.0 ("Accessing Protected Ressources")
		  $version = '1.0';
		}
		if ($version !== $this->version) {
		  throw new OAuthException("OAuth version '$version' not supported");
		}
		return $version;
	  }

	  /**
	   * figure out the signature with some defaults
	   */
	  private function get_signature_method(&$request) {
		$signature_method =
			@$request->get_parameter("oauth_signature_method");

		if (!$signature_method) {
		  // According to chapter 7 ("Accessing Protected Ressources") the signature-method
		  // parameter is required, and we can't just fallback to PLAINTEXT
		  throw new OAuthException('No signature method parameter. This parameter is required');
		}

		if (!in_array($signature_method,
					  array_keys($this->signature_methods))) {
		  throw new OAuthException(
			"Signature method '$signature_method' not supported " .
			"try one of the following: " .
			implode(", ", array_keys($this->signature_methods))
		  );
		}
		return $this->signature_methods[$signature_method];
	  }

	  /**
	   * try to find the consumer for the provided request's consumer key
	   */
	  private function get_consumer(&$request) {
		$consumer_key = @$request->get_parameter("oauth_consumer_key");
		if (!$consumer_key) {
		  throw new OAuthException("Invalid consumer key");
		}

		$consumer = $this->data_store->lookup_consumer($consumer_key);
		if (!$consumer) {
		  throw new OAuthException("Invalid consumer");
		}

		return $consumer;
	  }

	  /**
	   * try to find the token for the provided request's token key
	   */
	  private function get_token(&$request, $consumer, $token_type="access") {
		$token_field = @$request->get_parameter('oauth_token');
		$token = $this->data_store->lookup_token(
		  $consumer, $token_type, $token_field
		);
		if (!$token) {
		  throw new OAuthException("Invalid $token_type token: $token_field");
		}
		return $token;
	  }

	  /**
	   * all-in-one function to check the signature on a request
	   * should guess the signature method appropriately
	   */
	  private function check_signature(&$request, $consumer, $token) {
		// this should probably be in a different method
		$timestamp = @$request->get_parameter('oauth_timestamp');
		$nonce = @$request->get_parameter('oauth_nonce');

		$this->check_timestamp($timestamp);
		$this->check_nonce($consumer, $token, $nonce, $timestamp);

		$signature_method = $this->get_signature_method($request);

		$signature = $request->get_parameter('oauth_signature');
		$valid_sig = $signature_method->check_signature(
		  $request,
		  $consumer,
		  $token,
		  $signature
		);


		if (!$valid_sig) {
		  throw new OAuthException("Invalid signature");
		}
	  }

	  /**
	   * check that the timestamp is new enough
	   */
	  private function check_timestamp($timestamp) {
		if( ! $timestamp )
		  throw new OAuthException(
			'Missing timestamp parameter. The parameter is required'
		  );

		// verify that timestamp is recentish
		$now = time();
		if (abs($now - $timestamp) > $this->timestamp_threshold) {
		  throw new OAuthException(
			"Expired timestamp, yours $timestamp, ours $now"
		  );
		}
	  }

	  /**
	   * check that the nonce is not repeated
	   */
	  private function check_nonce($consumer, $token, $nonce, $timestamp) {
		if( ! $nonce )
		  throw new OAuthException(
			'Missing nonce parameter. The parameter is required'
		  );

		// verify that the nonce is uniqueish
		$found = $this->data_store->lookup_nonce(
		  $consumer,
		  $token,
		  $nonce,
		  $timestamp
		);
		if ($found) {
		  throw new OAuthException("Nonce already used: $nonce");
		}
	  }

	}

	class OAuthDataStore {
	  function lookup_consumer($consumer_key) {
		// implement me
	  }

	  function lookup_token($consumer, $token_type, $token) {
		// implement me
	  }

	  function lookup_nonce($consumer, $token, $nonce, $timestamp) {
		// implement me
	  }

	  function new_request_token($consumer, $callback = null) {
		// return a new token attached to this consumer
	  }

	  function new_access_token($token, $consumer, $verifier = null) {
		// return a new access token attached to this consumer
		// for the user associated with this token if the request token
		// is authorized
		// should also invalidate the request token
	  }

	}

	class OAuthUtil {
	  public static function urlencode_rfc3986($input) {
	  if (is_array($input)) {
		return array_map(array('OAuthUtil', 'urlencode_rfc3986'), $input);
	  } else if (is_scalar($input)) {
		return str_replace(
		  '+',
		  ' ',
		  str_replace('%7E', '~', rawurlencode($input))
		);
	  } else {
		return '';
	  }
	}


	  // This decode function isn't taking into consideration the above
	  // modifications to the encoding process. However, this method doesn't
	  // seem to be used anywhere so leaving it as is.
	  public static function urldecode_rfc3986($string) {
		return urldecode($string);
	  }

	  // Utility function for turning the Authorization: header into
	  // parameters, has to do some unescaping
	  // Can filter out any non-oauth parameters if needed (default behaviour)
	  public static function split_header($header, $only_allow_oauth_parameters = true) {
		$pattern = '/(([-_a-z]*)=("([^"]*)"|([^,]*)),?)/';
		$offset = 0;
		$params = array();
		while (preg_match($pattern, $header, $matches, PREG_OFFSET_CAPTURE, $offset) > 0) {
		  $match = $matches[0];
		  $header_name = $matches[2][0];
		  $header_content = (isset($matches[5])) ? $matches[5][0] : $matches[4][0];
		  if (preg_match('/^oauth_/', $header_name) || !$only_allow_oauth_parameters) {
			$params[$header_name] = OAuthUtil::urldecode_rfc3986($header_content);
		  }
		  $offset = $match[1] + strlen($match[0]);
		}

		if (isset($params['realm'])) {
		  unset($params['realm']);
		}

		return $params;
	  }

	  // helper to try to sort out headers for people who aren't running apache
	  public static function get_headers() {
		if (function_exists('apache_request_headers')) {
		  // we need this to get the actual Authorization: header
		  // because apache tends to tell us it doesn't exist
		  $headers = apache_request_headers();

		  // sanitize the output of apache_request_headers because
		  // we always want the keys to be Cased-Like-This and arh()
		  // returns the headers in the same case as they are in the
		  // request
		  $out = array();
		  foreach( $headers AS $key => $value ) {
			$key = str_replace(
				" ",
				"-",
				ucwords(strtolower(str_replace("-", " ", $key)))
			  );
			$out[$key] = $value;
		  }
		} else {
		  // otherwise we don't have apache and are just going to have to hope
		  // that $_SERVER actually contains what we need
		  $out = array();
		  if( isset($_SERVER['CONTENT_TYPE']) )
			$out['Content-Type'] = $_SERVER['CONTENT_TYPE'];
		  if( isset($_ENV['CONTENT_TYPE']) )
			$out['Content-Type'] = $_ENV['CONTENT_TYPE'];

		  foreach ($_SERVER as $key => $value) {
			if (substr($key, 0, 5) == "HTTP_") {
			  // this is chaos, basically it is just there to capitalize the first
			  // letter of every word that is not an initial HTTP and strip HTTP
			  // code from przemek
			  $key = str_replace(
				" ",
				"-",
				ucwords(strtolower(str_replace("_", " ", substr($key, 5))))
			  );
			  $out[$key] = $value;
			}
		  }
		}
		return $out;
	  }

	  // This function takes a input like a=b&a=c&d=e and returns the parsed
	  // parameters like this
	  // array('a' => array('b','c'), 'd' => 'e')
	  public static function parse_parameters( $input ) {
		if (!isset($input) || !$input) return array();

		$pairs = explode('&', $input);

		$parsed_parameters = array();
		foreach ($pairs as $pair) {
		  $split = explode('=', $pair, 2);
		  $parameter = OAuthUtil::urldecode_rfc3986($split[0]);
		  $value = isset($split[1]) ? OAuthUtil::urldecode_rfc3986($split[1]) : '';

		  if (isset($parsed_parameters[$parameter])) {
			// We have already recieved parameter(s) with this name, so add to the list
			// of parameters with this name

			if (is_scalar($parsed_parameters[$parameter])) {
			  // This is the first duplicate, so transform scalar (string) into an array
			  // so we can add the duplicates
			  $parsed_parameters[$parameter] = array($parsed_parameters[$parameter]);
			}

			$parsed_parameters[$parameter][] = $value;
		  } else {
			$parsed_parameters[$parameter] = $value;
		  }
		}
		return $parsed_parameters;
	  }

	  public static function build_http_query($params) {
		if (!$params) return '';

		// Urlencode both keys and values
		$keys = OAuthUtil::urlencode_rfc3986(array_keys($params));
		$values = OAuthUtil::urlencode_rfc3986(array_values($params));
		$params = array_combine($keys, $values);

		// Parameters are sorted by name, using lexicographical byte value ordering.
		// Ref: Spec: 9.1.1 (1)
		uksort($params, 'strcmp');

		$pairs = array();
		foreach ($params as $parameter => $value) {
		  if (is_array($value)) {
			// If two or more parameters share the same name, they are sorted by their value
			// Ref: Spec: 9.1.1 (1)
			natsort($value);
			foreach ($value as $duplicate_value) {
			  $pairs[] = $parameter . '=' . $duplicate_value;
			}
		  } else {
			$pairs[] = $parameter . '=' . $value;
		  }
		}
		// For each parameter, the name is separated from the corresponding value by an '=' character (ASCII code 61)
		// Each name-value pair is separated by an '&' character (ASCII code 38)
		return implode('&', $pairs);
	  }
	}
}