Adding Chrome Web Store PHP Hello World

chrome/common/extensions/docs/examples/apps/hello-php/lib/oauth/OAuth.php

+<?php
+// vim: foldmethod=marker
+
+/* Generic exception class
+ */
+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);
+    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);
+
+    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 = 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 {
+  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 : 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';
+    $http_url = ($http_url) ? $http_url : $scheme .
+                              '://' . $_SERVER['HTTP_HOST'] .
+                              ':' .
+                              $_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 : 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);
+
+    $scheme = (isset($parts['scheme'])) ? $parts['scheme'] : 'http';
+    $port = (isset($parts['port'])) ? $parts['port'] : (($scheme == 'https') ? '443' : '80');
+    $host = (isset($parts['host'])) ? $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';
+
+    $total = array();
+    foreach ($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);
+    $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 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(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($string);
+  }
+
+  // Utility function for turning the Authorization: header into
+  // parameters, has to do some unescaping
+  // Can filter out any non-oauth parameters if needed (default behaviour)
+  // May 28th, 2010 - method updated to tjerk.meesters for a speed improvement.
+  //                  see http://code.google.com/p/oauth/issues/detail?id=163
+  public static function split_header($header, $only_allow_oauth_parameters = true) {
+    $params = array();
+    if (preg_match_all('/('.($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
+      $out = array();
+      foreach ($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)
+        // 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);
+  }
+}
+
+?>