PHP Example
===========

.. code-block:: php
	:caption: example.php
	:name: example-php

	<?php
	        require("OAuth.php");

	        $cc_key  = "CLIENT_KEY_HERE";
	        $cc_secret = "CLIENT_SECRET_HERE";
	        $url = "https://api.thenounproject.com/v2/icon";
	        $args = array();
	        $args["query"] = "happy";
	        $args["limit"] = 10;

	        $consumer = new OAuthConsumer($cc_key, $cc_secret);
	        $request = OAuthRequest::from_consumer_and_token($consumer, NULL,"GET", $url, $args);
	        $request->sign_request(new OAuthSignatureMethod_HMAC_SHA1(), $consumer, NULL);
	        $url = sprintf("%s?%s", $url, OAuthUtil::build_http_query($args));
	        $ch = curl_init();
	        $headers = array($request->to_header());
	        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
	        curl_setopt($ch, CURLOPT_URL, $url);
	        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
	        $rsp = curl_exec($ch);
	        print_r($rsp)
	?>

.. code-block:: php
	:caption: OAuth.php
	:name: oauth-php

	<?php

	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;

	    /**
	     * 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);

	        // Check for zero length, although unlikely here
	        if (strlen($built) == 0 || strlen($signature) == 0) {
	            return false;
	        }

	        if (strlen($built) != strlen($signature)) {
	            return false;
	        }

	        // Avoid a timing leak with a (hopefully) time insensitive compare
	        $result = 0;
	        for ($i = 0; $i < strlen($signature); $i++) {
	            $result |= ord($built[$i]) ^ ord($signature[$i]);
	        }

	        return $result == 0;
	    }
	}

	/**
	 * 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;

	        $key_parts = [$consumer->secret, $token ? $token->secret : ""];

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

	        return base64_encode(hash_hmac("sha1", $base_string, $key, true));
	    }
	}

	/**
	 * 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)
	    {
	        $key_parts = [$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
	    abstract protected 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
	    abstract protected 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
	{
	    protected $parameters;
	    protected $http_method;
	    protected $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 = $parameters ? $parameters : [];
	        $parameters = array_merge(
	            OAuthUtil::parse_parameters(parse_url($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 = $http_url
	            ? $http_url
	            : $scheme .
	                "://" .
	                $_SERVER["SERVER_NAME"] .
	                ":" .
	                $_SERVER["SERVER_PORT"] .
	                $_SERVER["REQUEST_URI"];
	        $http_method = $http_method ? $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 (
	                $http_method == "POST" &&
	                isset($request_headers["Content-Type"]) &&
	                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 (
	                isset($request_headers["Authorization"]) &&
	                substr($request_headers["Authorization"], 0, 6) == "OAuth "
	            ) {
	                $header_parameters = OAuthUtil::split_header(
	                    $request_headers["Authorization"]
	                );
	                $parameters = array_merge($parameters, $header_parameters);
	            }
	        }

	        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 = $parameters ? $parameters : [];
	        $defaults = [
	            "oauth_version" => OAuthRequest::$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] = [$this->parameters[$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 = [
	            $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);

	        $scheme = isset($parts["scheme"]) ? $parts["scheme"] : "http";
	        $port = isset($parts["port"])
	            ? $parts["port"]
	            : ($scheme == "https"
	                ? "443"
	                : "80");
	        $host = isset($parts["host"]) ? strtolower($parts["host"]) : "";
	        $path = isset($parts["path"]) ? $parts["path"] : "";

	        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()
	    {
	        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";
	        }

	        $total = [];
	        foreach ($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 = [];

	    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);
	        $token = $this->get_token($request, $consumer, "access");
	        $this->check_signature($request, $consumer, $token);
	        return [$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 instanceof OAuthRequest
	                ? $request->get_parameter("oauth_signature_method")
	                : null;

	        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 instanceof OAuthRequest
	                ? $request->get_parameter("oauth_consumer_key")
	                : null;

	        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 instanceof OAuthRequest
	                ? $request->get_parameter("oauth_token")
	                : null;

	        $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 instanceof OAuthRequest
	                ? $request->get_parameter("oauth_timestamp")
	                : null;
	        $nonce =
	            $request instanceof OAuthRequest
	                ? $request->get_parameter("oauth_nonce")
	                : null;

	        $this->check_timestamp($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(["OAuthUtil", "urlencode_rfc3986"], $input);
	        } elseif (is_scalar($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)
	    // May 28th, 2010 - method updated to tjerk.meesters for a speed improvement.
	    //                  see http://code.google.com/p/oauth/issues/detail?id=163
	    public static function split_header(
	        $header,
	        $only_allow_oauth_parameters = true
	    ) {
	        $params = [];
	        if (
	            preg_match_all(
	                "/(" .
	                    ($only_allow_oauth_parameters ? "oauth_" : "") .
	                    '[a-z_-]*)=(:?"([^"]*)"|([^,]*))/',
	                $header,
	                $matches
	            )
	        ) {
	            foreach ($matches[1] as $i => $h) {
	                $params[$h] = OAuthUtil::urldecode_rfc3986(
	                    empty($matches[3][$i]) ? $matches[4][$i] : $matches[3][$i]
	                );
	            }
	            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
	            $out = [];
	            foreach ($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
	            $out = [];
	            if (isset($_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 [];
	        }

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

	        $parsed_parameters = [];
	        foreach ($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] = [
	                        $parsed_parameters[$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");

	        $pairs = [];
	        foreach ($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)
	                // June 12th, 2010 - changed to sort because of issue 164 by hidetaka
	                sort($value, SORT_STRING);
	                foreach ($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);
	    }
	}

	?>