nounproject_api_v2.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)
?>

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);
    }
}

?>