lib/twitteroauth/OAuth.php

   1 <?php
   2 // vim: foldmethod=marker
   3
   4 /* Generic exception class
   5  */
   6 class OAuthException extends Exception {
   7   // pass
   8 }
   9
  10 class OAuthConsumer {
  11   public $key;
  12   public $secret;
  13
  14   function __construct($key, $secret, $callback_url=NULL) {
  15     $this->key = $key;
  16     $this->secret = $secret;
  17     $this->callback_url = $callback_url;
  18   }
  19
  20   function __toString() {
  21     return "OAuthConsumer[key=$this->key,secret=$this->secret]";
  22   }
  23 }
  24
  25 class OAuthToken {
  26   // access tokens and request tokens
  27   public $key;
  28   public $secret;
  29
  30   /**
  31    * key = the token
  32    * secret = the token secret
  33    */
  34   function __construct($key, $secret) {
  35     $this->key = $key;
  36     $this->secret = $secret;
  37   }
  38
  39   /**
  40    * generates the basic string serialization of a token that a server
  41    * would respond to request_token and access_token calls with
  42    */
  43   function to_string() {
  44     return "oauth_token=" .
  45            OAuthUtil::urlencode_rfc3986($this->key) .
  46            "&oauth_token_secret=" .
  47            OAuthUtil::urlencode_rfc3986($this->secret);
  48   }
  49
  50   function __toString() {
  51     return $this->to_string();
  52   }
  53 }
  54
  55 /**
  56  * A class for implementing a Signature Method
  57  * See section 9 ("Signing Requests") in the spec
  58  */
  59 abstract class OAuthSignatureMethod {
  60   /**
  61    * Needs to return the name of the Signature Method (ie HMAC-SHA1)
  62    * @return string
  63    */
  64   abstract public function get_name();
  65
  66   /**
  67    * Build up the signature
  68    * NOTE: The output of this function MUST NOT be urlencoded.
  69    * the encoding is handled in OAuthRequest when the final
  70    * request is serialized
  71    * @param OAuthRequest $request
  72    * @param OAuthConsumer $consumer
  73    * @param OAuthToken $token
  74    * @return string
  75    */
  76   abstract public function build_signature($request, $consumer, $token);
  77
  78   /**
  79    * Verifies that a given signature is correct
  80    * @param OAuthRequest $request
  81    * @param OAuthConsumer $consumer
  82    * @param OAuthToken $token
  83    * @param string $signature
  84    * @return bool
  85    */
  86   public function check_signature($request, $consumer, $token, $signature) {
  87     $built = $this->build_signature($request, $consumer, $token);
  88     return $built == $signature;
  89   }
  90 }
  91
  92 /**
  93  * The HMAC-SHA1 signature method uses the HMAC-SHA1 signature algorithm as defined in [RFC2104]
  94  * where the Signature Base String is the text and the key is the concatenated values (each first
  95  * encoded per Parameter Encoding) of the Consumer Secret and Token Secret, separated by an '&'
  96  * character (ASCII code 38) even if empty.
  97  *   - Chapter 9.2 ("HMAC-SHA1")
  98  */
  99 class OAuthSignatureMethod_HMAC_SHA1 extends OAuthSignatureMethod {
 100   function get_name() {
 101     return "HMAC-SHA1";
 102   }
 103
 104   public function build_signature($request, $consumer, $token) {
 105     $base_string = $request->get_signature_base_string();
 106     $request->base_string = $base_string;
 107
 108     $key_parts = array(
 109       $consumer->secret,
 110       ($token) ? $token->secret : ""
 111     );
 112
 113     $key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
 114     $key = implode('&', $key_parts);
 115
 116     return base64_encode(hash_hmac('sha1', $base_string, $key, true));
 117   }
 118 }
 119
 120 /**
 121  * The PLAINTEXT method does not provide any security protection and SHOULD only be used
 122  * over a secure channel such as HTTPS. It does not use the Signature Base String.
 123  *   - Chapter 9.4 ("PLAINTEXT")
 124  */
 125 class OAuthSignatureMethod_PLAINTEXT extends OAuthSignatureMethod {
 126   public function get_name() {
 127     return "PLAINTEXT";
 128   }
 129
 130   /**
 131    * oauth_signature is set to the concatenated encoded values of the Consumer Secret and
 132    * Token Secret, separated by a '&' character (ASCII code 38), even if either secret is
 133    * empty. The result MUST be encoded again.
 134    *   - Chapter 9.4.1 ("Generating Signatures")
 135    *
 136    * Please note that the second encoding MUST NOT happen in the SignatureMethod, as
 137    * OAuthRequest handles this!
 138    */
 139   public function build_signature($request, $consumer, $token) {
 140     $key_parts = array(
 141       $consumer->secret,
 142       ($token) ? $token->secret : ""
 143     );
 144
 145     $key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
 146     $key = implode('&', $key_parts);
 147     $request->base_string = $key;
 148
 149     return $key;
 150   }
 151 }
 152
 153 /**
 154  * The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature algorithm as defined in
 155  * [RFC3447] section 8.2 (more simply known as PKCS#1), using SHA-1 as the hash function for
 156  * EMSA-PKCS1-v1_5. It is assumed that the Consumer has provided its RSA public key in a
 157  * verified way to the Service Provider, in a manner which is beyond the scope of this
 158  * specification.
 159  *   - Chapter 9.3 ("RSA-SHA1")
 160  */
 161 abstract class OAuthSignatureMethod_RSA_SHA1 extends OAuthSignatureMethod {
 162   public function get_name() {
 163     return "RSA-SHA1";
 164   }
 165
 166   // Up to the SP to implement this lookup of keys. Possible ideas are:
 167   // (1) do a lookup in a table of trusted certs keyed off of consumer
 168   // (2) fetch via http using a url provided by the requester
 169   // (3) some sort of specific discovery code based on request
 170   //
 171   // Either way should return a string representation of the certificate
 172   protected abstract function fetch_public_cert(&$request);
 173
 174   // Up to the SP to implement this lookup of keys. Possible ideas are:
 175   // (1) do a lookup in a table of trusted certs keyed off of consumer
 176   //
 177   // Either way should return a string representation of the certificate
 178   protected abstract function fetch_private_cert(&$request);
 179
 180   public function build_signature($request, $consumer, $token) {
 181     $base_string = $request->get_signature_base_string();
 182     $request->base_string = $base_string;
 183
 184     // Fetch the private key cert based on the request
 185     $cert = $this->fetch_private_cert($request);
 186
 187     // Pull the private key ID from the certificate
 188     $privatekeyid = openssl_get_privatekey($cert);
 189
 190     // Sign using the key
 191     $ok = openssl_sign($base_string, $signature, $privatekeyid);
 192
 193     // Release the key resource
 194     openssl_free_key($privatekeyid);
 195
 196     return base64_encode($signature);
 197   }
 198
 199   public function check_signature($request, $consumer, $token, $signature) {
 200     $decoded_sig = base64_decode($signature);
 201
 202     $base_string = $request->get_signature_base_string();
 203
 204     // Fetch the public key cert based on the request
 205     $cert = $this->fetch_public_cert($request);
 206
 207     // Pull the public key ID from the certificate
 208     $publickeyid = openssl_get_publickey($cert);
 209
 210     // Check the computed signature against the one passed in the query
 211     $ok = openssl_verify($base_string, $decoded_sig, $publickeyid);
 212
 213     // Release the key resource
 214     openssl_free_key($publickeyid);
 215
 216     return $ok == 1;
 217   }
 218 }
 219
 220 class OAuthRequest {
 221   private $parameters;
 222   private $http_method;
 223   private $http_url;
 224   // for debug purposes
 225   public $base_string;
 226   public static $version = '1.0';
 227   public static $POST_INPUT = 'php://input';
 228
 229   function __construct($http_method, $http_url, $parameters=NULL) {
 230     @$parameters or $parameters = array();
 231     $parameters = array_merge( OAuthUtil::parse_parameters(parse_url($http_url, PHP_URL_QUERY)), $parameters);
 232     $this->parameters = $parameters;
 233     $this->http_method = $http_method;
 234     $this->http_url = $http_url;
 235   }
 236
 237
 238   /**
 239    * attempt to build up a request from what was passed to the server
 240    */
 241   public static function from_request($http_method=NULL, $http_url=NULL, $parameters=NULL) {
 242     $scheme = (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on")
 243               ? 'http'
 244               : 'https';
 245     @$http_url or $http_url = $scheme .
 246                               '://' . $_SERVER['HTTP_HOST'] .
 247                               ':' .
 248                               $_SERVER['SERVER_PORT'] .
 249                               $_SERVER['REQUEST_URI'];
 250     @$http_method or $http_method = $_SERVER['REQUEST_METHOD'];
 251
 252     // We weren't handed any parameters, so let's find the ones relevant to
 253     // this request.
 254     // If you run XML-RPC or similar you should use this to provide your own
 255     // parsed parameter-list
 256     if (!$parameters) {
 257       // Find request headers
 258       $request_headers = OAuthUtil::get_headers();
 259
 260       // Parse the query-string to find GET parameters
 261       $parameters = OAuthUtil::parse_parameters($_SERVER['QUERY_STRING']);
 262
 263       // It's a POST request of the proper content-type, so parse POST
 264       // parameters and add those overriding any duplicates from GET
 265       if ($http_method == "POST"
 266           && @strstr($request_headers["Content-Type"],
 267                      "application/x-www-form-urlencoded")
 268           ) {
 269         $post_data = OAuthUtil::parse_parameters(
 270           file_get_contents(self::$POST_INPUT)
 271         );
 272         $parameters = array_merge($parameters, $post_data);
 273       }
 274
 275       // We have a Authorization-header with OAuth data. Parse the header
 276       // and add those overriding any duplicates from GET or POST
 277       if (@substr($request_headers['Authorization'], 0, 6) == "OAuth ") {
 278         $header_parameters = OAuthUtil::split_header(
 279           $request_headers['Authorization']
 280         );
 281         $parameters = array_merge($parameters, $header_parameters);
 282       }
 283
 284     }
 285
 286     return new OAuthRequest($http_method, $http_url, $parameters);
 287   }
 288
 289   /**
 290    * pretty much a helper function to set up the request
 291    */
 292   public static function from_consumer_and_token($consumer, $token, $http_method, $http_url, $parameters=NULL) {
 293     @$parameters or $parameters = array();
 294     $defaults = array("oauth_version" => OAuthRequest::$version,
 295                       "oauth_nonce" => OAuthRequest::generate_nonce(),
 296                       "oauth_timestamp" => OAuthRequest::generate_timestamp(),
 297                       "oauth_consumer_key" => $consumer->key);
 298     if ($token)
 299       $defaults['oauth_token'] = $token->key;
 300
 301     $parameters = array_merge($defaults, $parameters);
 302
 303     return new OAuthRequest($http_method, $http_url, $parameters);
 304   }
 305
 306   public function set_parameter($name, $value, $allow_duplicates = true) {
 307     if ($allow_duplicates && isset($this->parameters[$name])) {
 308       // We have already added parameter(s) with this name, so add to the list
 309       if (is_scalar($this->parameters[$name])) {
 310         // This is the first duplicate, so transform scalar (string)
 311         // into an array so we can add the duplicates
 312         $this->parameters[$name] = array($this->parameters[$name]);
 313       }
 314
 315       $this->parameters[$name][] = $value;
 316     } else {
 317       $this->parameters[$name] = $value;
 318     }
 319   }
 320
 321   public function get_parameter($name) {
 322     return isset($this->parameters[$name]) ? $this->parameters[$name] : null;
 323   }
 324
 325   public function get_parameters() {
 326     return $this->parameters;
 327   }
 328
 329   public function unset_parameter($name) {
 330     unset($this->parameters[$name]);
 331   }
 332
 333   /**
 334    * The request parameters, sorted and concatenated into a normalized string.
 335    * @return string
 336    */
 337   public function get_signable_parameters() {
 338     // Grab all parameters
 339     $params = $this->parameters;
 340
 341     // Remove oauth_signature if present
 342     // Ref: Spec: 9.1.1 ("The oauth_signature parameter MUST be excluded.")
 343     if (isset($params['oauth_signature'])) {
 344       unset($params['oauth_signature']);
 345     }
 346
 347     return OAuthUtil::build_http_query($params);
 348   }
 349
 350   /**
 351    * Returns the base string of this request
 352    *
 353    * The base string defined as the method, the url
 354    * and the parameters (normalized), each urlencoded
 355    * and the concated with &.
 356    */
 357   public function get_signature_base_string() {
 358     $parts = array(
 359       $this->get_normalized_http_method(),
 360       $this->get_normalized_http_url(),
 361       $this->get_signable_parameters()
 362     );
 363
 364     $parts = OAuthUtil::urlencode_rfc3986($parts);
 365
 366     return implode('&', $parts);
 367   }
 368
 369   /**
 370    * just uppercases the http method
 371    */
 372   public function get_normalized_http_method() {
 373     return strtoupper($this->http_method);
 374   }
 375
 376   /**
 377    * parses the url and rebuilds it to be
 378    * scheme://host/path
 379    */
 380   public function get_normalized_http_url() {
 381     $parts = parse_url($this->http_url);
 382
 383     $port = @$parts['port'];
 384     $scheme = $parts['scheme'];
 385     $host = $parts['host'];
 386     $path = @$parts['path'];
 387
 388     $port or $port = ($scheme == 'https') ? '443' : '80';
 389
 390     if (($scheme == 'https' && $port != '443')
 391         || ($scheme == 'http' && $port != '80')) {
 392       $host = "$host:$port";
 393     }
 394     return "$scheme://$host$path";
 395   }
 396
 397   /**
 398    * builds a url usable for a GET request
 399    */
 400   public function to_url() {
 401     $post_data = $this->to_postdata();
 402     $out = $this->get_normalized_http_url();
 403     if ($post_data) {
 404       $out .= '?'.$post_data;
 405     }
 406     return $out;
 407   }
 408
 409   /**
 410    * builds the data one would send in a POST request
 411    */
 412   public function to_postdata() {
 413     return OAuthUtil::build_http_query($this->parameters);
 414   }
 415
 416   /**
 417    * builds the Authorization: header
 418    */
 419   public function to_header($realm=null) {
 420     $first = true;
 421         if($realm) {
 422       $out = 'Authorization: OAuth realm="' . OAuthUtil::urlencode_rfc3986($realm) . '"';
 423       $first = false;
 424     } else
 425       $out = 'Authorization: OAuth';
 426
 427     $total = array();
 428     foreach ($this->parameters as $k => $v) {
 429       if (substr($k, 0, 5) != "oauth") continue;
 430       if (is_array($v)) {
 431         throw new OAuthException('Arrays not supported in headers');
 432       }
 433       $out .= ($first) ? ' ' : ',';
 434       $out .= OAuthUtil::urlencode_rfc3986($k) .
 435               '="' .
 436               OAuthUtil::urlencode_rfc3986($v) .
 437               '"';
 438       $first = false;
 439     }
 440     return $out;
 441   }
 442
 443   public function __toString() {
 444     return $this->to_url();
 445   }
 446
 447
 448   public function sign_request($signature_method, $consumer, $token) {
 449     $this->set_parameter(
 450       "oauth_signature_method",
 451       $signature_method->get_name(),
 452       false
 453     );
 454     $signature = $this->build_signature($signature_method, $consumer, $token);
 455     $this->set_parameter("oauth_signature", $signature, false);
 456   }
 457
 458   public function build_signature($signature_method, $consumer, $token) {
 459     $signature = $signature_method->build_signature($this, $consumer, $token);
 460     return $signature;
 461   }
 462
 463   /**
 464    * util function: current timestamp
 465    */
 466   private static function generate_timestamp() {
 467     return time();
 468   }
 469
 470   /**
 471    * util function: current nonce
 472    */
 473   private static function generate_nonce() {
 474     $mt = microtime();
 475     $rand = mt_rand();
 476
 477     return md5($mt . $rand); // md5s look nicer than numbers
 478   }
 479 }
 480
 481 class OAuthServer {
 482   protected $timestamp_threshold = 300; // in seconds, five minutes
 483   protected $version = '1.0';             // hi blaine
 484   protected $signature_methods = array();
 485
 486   protected $data_store;
 487
 488   function __construct($data_store) {
 489     $this->data_store = $data_store;
 490   }
 491
 492   public function add_signature_method($signature_method) {
 493     $this->signature_methods[$signature_method->get_name()] =
 494       $signature_method;
 495   }
 496
 497   // high level functions
 498
 499   /**
 500    * process a request_token request
 501    * returns the request token on success
 502    */
 503   public function fetch_request_token(&$request) {
 504     $this->get_version($request);
 505
 506     $consumer = $this->get_consumer($request);
 507
 508     // no token required for the initial token request
 509     $token = NULL;
 510
 511     $this->check_signature($request, $consumer, $token);
 512
 513     // Rev A change
 514     $callback = $request->get_parameter('oauth_callback');
 515     $new_token = $this->data_store->new_request_token($consumer, $callback);
 516
 517     return $new_token;
 518   }
 519
 520   /**
 521    * process an access_token request
 522    * returns the access token on success
 523    */
 524   public function fetch_access_token(&$request) {
 525     $this->get_version($request);
 526
 527     $consumer = $this->get_consumer($request);
 528
 529     // requires authorized request token
 530     $token = $this->get_token($request, $consumer, "request");
 531
 532     $this->check_signature($request, $consumer, $token);
 533
 534     // Rev A change
 535     $verifier = $request->get_parameter('oauth_verifier');
 536     $new_token = $this->data_store->new_access_token($token, $consumer, $verifier);
 537
 538     return $new_token;
 539   }
 540
 541   /**
 542    * verify an api call, checks all the parameters
 543    */
 544   public function verify_request(&$request) {
 545     $this->get_version($request);
 546     $consumer = $this->get_consumer($request);
 547     $token = $this->get_token($request, $consumer, "access");
 548     $this->check_signature($request, $consumer, $token);
 549     return array($consumer, $token);
 550   }
 551
 552   // Internals from here
 553   /**
 554    * version 1
 555    */
 556   private function get_version(&$request) {
 557     $version = $request->get_parameter("oauth_version");
 558     if (!$version) {
 559       // Service Providers MUST assume the protocol version to be 1.0 if this parameter is not present.
 560       // Chapter 7.0 ("Accessing Protected Ressources")
 561       $version = '1.0';
 562     }
 563     if ($version !== $this->version) {
 564       throw new OAuthException("OAuth version '$version' not supported");
 565     }
 566     return $version;
 567   }
 568
 569   /**
 570    * figure out the signature with some defaults
 571    */
 572   private function get_signature_method(&$request) {
 573     $signature_method =
 574         @$request->get_parameter("oauth_signature_method");
 575
 576     if (!$signature_method) {
 577       // According to chapter 7 ("Accessing Protected Ressources") the signature-method
 578       // parameter is required, and we can't just fallback to PLAINTEXT
 579       throw new OAuthException('No signature method parameter. This parameter is required');
 580     }
 581
 582     if (!in_array($signature_method,
 583                   array_keys($this->signature_methods))) {
 584       throw new OAuthException(
 585         "Signature method '$signature_method' not supported " .
 586         "try one of the following: " .
 587         implode(", ", array_keys($this->signature_methods))
 588       );
 589     }
 590     return $this->signature_methods[$signature_method];
 591   }
 592
 593   /**
 594    * try to find the consumer for the provided request's consumer key
 595    */
 596   private function get_consumer(&$request) {
 597     $consumer_key = @$request->get_parameter("oauth_consumer_key");
 598     if (!$consumer_key) {
 599       throw new OAuthException("Invalid consumer key");
 600     }
 601
 602     $consumer = $this->data_store->lookup_consumer($consumer_key);
 603     if (!$consumer) {
 604       throw new OAuthException("Invalid consumer");
 605     }
 606
 607     return $consumer;
 608   }
 609
 610   /**
 611    * try to find the token for the provided request's token key
 612    */
 613   private function get_token(&$request, $consumer, $token_type="access") {
 614     $token_field = @$request->get_parameter('oauth_token');
 615     $token = $this->data_store->lookup_token(
 616       $consumer, $token_type, $token_field
 617     );
 618     if (!$token) {
 619       throw new OAuthException("Invalid $token_type token: $token_field");
 620     }
 621     return $token;
 622   }
 623
 624   /**
 625    * all-in-one function to check the signature on a request
 626    * should guess the signature method appropriately
 627    */
 628   private function check_signature(&$request, $consumer, $token) {
 629     // this should probably be in a different method
 630     $timestamp = @$request->get_parameter('oauth_timestamp');
 631     $nonce = @$request->get_parameter('oauth_nonce');
 632
 633     $this->check_timestamp($timestamp);
 634     $this->check_nonce($consumer, $token, $nonce, $timestamp);
 635
 636     $signature_method = $this->get_signature_method($request);
 637
 638     $signature = $request->get_parameter('oauth_signature');
 639     $valid_sig = $signature_method->check_signature(
 640       $request,
 641       $consumer,
 642       $token,
 643       $signature
 644     );
 645
 646     if (!$valid_sig) {
 647       throw new OAuthException("Invalid signature");
 648     }
 649   }
 650
 651   /**
 652    * check that the timestamp is new enough
 653    */
 654   private function check_timestamp($timestamp) {
 655     if( ! $timestamp )
 656       throw new OAuthException(
 657         'Missing timestamp parameter. The parameter is required'
 658       );
 659
 660     // verify that timestamp is recentish
 661     $now = time();
 662     if (abs($now - $timestamp) > $this->timestamp_threshold) {
 663       throw new OAuthException(
 664         "Expired timestamp, yours $timestamp, ours $now"
 665       );
 666     }
 667   }
 668
 669   /**
 670    * check that the nonce is not repeated
 671    */
 672   private function check_nonce($consumer, $token, $nonce, $timestamp) {
 673     if( ! $nonce )
 674       throw new OAuthException(
 675         'Missing nonce parameter. The parameter is required'
 676       );
 677
 678     // verify that the nonce is uniqueish
 679     $found = $this->data_store->lookup_nonce(
 680       $consumer,
 681       $token,
 682       $nonce,
 683       $timestamp
 684     );
 685     if ($found) {
 686       throw new OAuthException("Nonce already used: $nonce");
 687     }
 688   }
 689
 690 }
 691
 692 class OAuthDataStore {
 693   function lookup_consumer($consumer_key) {
 694     // implement me
 695   }
 696
 697   function lookup_token($consumer, $token_type, $token) {
 698     // implement me
 699   }
 700
 701   function lookup_nonce($consumer, $token, $nonce, $timestamp) {
 702     // implement me
 703   }
 704
 705   function new_request_token($consumer, $callback = null) {
 706     // return a new token attached to this consumer
 707   }
 708
 709   function new_access_token($token, $consumer, $verifier = null) {
 710     // return a new access token attached to this consumer
 711     // for the user associated with this token if the request token
 712     // is authorized
 713     // should also invalidate the request token
 714   }
 715
 716 }
 717
 718 class OAuthUtil {
 719   public static function urlencode_rfc3986($input) {
 720   if (is_array($input)) {
 721     return array_map(array('OAuthUtil', 'urlencode_rfc3986'), $input);
 722   } else if (is_scalar($input)) {
 723     return str_replace(
 724       '+',
 725       ' ',
 726       str_replace('%7E', '~', rawurlencode($input))
 727     );
 728   } else {
 729     return '';
 730   }
 731 }
 732
 733
 734   // This decode function isn't taking into consideration the above
 735   // modifications to the encoding process. However, this method doesn't
 736   // seem to be used anywhere so leaving it as is.
 737   public static function urldecode_rfc3986($string) {
 738     return urldecode($string);
 739   }
 740
 741   // Utility function for turning the Authorization: header into
 742   // parameters, has to do some unescaping
 743   // Can filter out any non-oauth parameters if needed (default behaviour)
 744   public static function split_header($header, $only_allow_oauth_parameters = true) {
 745     $pattern = '/(([-_a-z]*)=("([^"]*)"|([^,]*)),?)/';
 746     $offset = 0;
 747     $params = array();
 748     while (preg_match($pattern, $header, $matches, PREG_OFFSET_CAPTURE, $offset) > 0) {
 749       $match = $matches[0];
 750       $header_name = $matches[2][0];
 751       $header_content = (isset($matches[5])) ? $matches[5][0] : $matches[4][0];
 752       if (preg_match('/^oauth_/', $header_name) || !$only_allow_oauth_parameters) {
 753         $params[$header_name] = OAuthUtil::urldecode_rfc3986($header_content);
 754       }
 755       $offset = $match[1] + strlen($match[0]);
 756     }
 757
 758     if (isset($params['realm'])) {
 759       unset($params['realm']);
 760     }
 761
 762     return $params;
 763   }
 764
 765   // helper to try to sort out headers for people who aren't running apache
 766   public static function get_headers() {
 767     if (function_exists('apache_request_headers')) {
 768       // we need this to get the actual Authorization: header
 769       // because apache tends to tell us it doesn't exist
 770       $headers = apache_request_headers();
 771
 772       // sanitize the output of apache_request_headers because
 773       // we always want the keys to be Cased-Like-This and arh()
 774       // returns the headers in the same case as they are in the
 775       // request
 776       $out = array();
 777       foreach( $headers AS $key => $value ) {
 778         $key = str_replace(
 779             " ",
 780             "-",
 781             ucwords(strtolower(str_replace("-", " ", $key)))
 782           );
 783         $out[$key] = $value;
 784       }
 785     } else {
 786       // otherwise we don't have apache and are just going to have to hope
 787       // that $_SERVER actually contains what we need
 788       $out = array();
 789       if( isset($_SERVER['CONTENT_TYPE']) )
 790         $out['Content-Type'] = $_SERVER['CONTENT_TYPE'];
 791       if( isset($_ENV['CONTENT_TYPE']) )
 792         $out['Content-Type'] = $_ENV['CONTENT_TYPE'];
 793
 794       foreach ($_SERVER as $key => $value) {
 795         if (substr($key, 0, 5) == "HTTP_") {
 796           // this is chaos, basically it is just there to capitalize the first
 797           // letter of every word that is not an initial HTTP and strip HTTP
 798           // code from przemek
 799           $key = str_replace(
 800             " ",
 801             "-",
 802             ucwords(strtolower(str_replace("_", " ", substr($key, 5))))
 803           );
 804           $out[$key] = $value;
 805         }
 806       }
 807     }
 808     return $out;
 809   }
 810
 811   // This function takes a input like a=b&a=c&d=e and returns the parsed
 812   // parameters like this
 813   // array('a' => array('b','c'), 'd' => 'e')
 814   public static function parse_parameters( $input ) {
 815     if (!isset($input) || !$input) return array();
 816
 817     $pairs = explode('&', $input);
 818
 819     $parsed_parameters = array();
 820     foreach ($pairs as $pair) {
 821       $split = explode('=', $pair, 2);
 822       $parameter = OAuthUtil::urldecode_rfc3986($split[0]);
 823       $value = isset($split[1]) ? OAuthUtil::urldecode_rfc3986($split[1]) : '';
 824
 825       if (isset($parsed_parameters[$parameter])) {
 826         // We have already recieved parameter(s) with this name, so add to the list
 827         // of parameters with this name
 828
 829         if (is_scalar($parsed_parameters[$parameter])) {
 830           // This is the first duplicate, so transform scalar (string) into an array
 831           // so we can add the duplicates
 832           $parsed_parameters[$parameter] = array($parsed_parameters[$parameter]);
 833         }
 834
 835         $parsed_parameters[$parameter][] = $value;
 836       } else {
 837         $parsed_parameters[$parameter] = $value;
 838       }
 839     }
 840     return $parsed_parameters;
 841   }
 842
 843   public static function build_http_query($params) {
 844     if (!$params) return '';
 845
 846     // Urlencode both keys and values
 847     $keys = OAuthUtil::urlencode_rfc3986(array_keys($params));
 848     $values = OAuthUtil::urlencode_rfc3986(array_values($params));
 849     $params = array_combine($keys, $values);
 850
 851     // Parameters are sorted by name, using lexicographical byte value ordering.
 852     // Ref: Spec: 9.1.1 (1)
 853     uksort($params, 'strcmp');
 854
 855     $pairs = array();
 856     foreach ($params as $parameter => $value) {
 857       if (is_array($value)) {
 858         // If two or more parameters share the same name, they are sorted by their value
 859         // Ref: Spec: 9.1.1 (1)
 860         natsort($value);
 861         foreach ($value as $duplicate_value) {
 862           $pairs[] = $parameter . '=' . $duplicate_value;
 863         }
 864       } else {
 865         $pairs[] = $parameter . '=' . $value;
 866       }
 867     }
 868     // For each parameter, the name is separated from the corresponding value by an '=' character (ASCII code 61)
 869     // Each name-value pair is separated by an '&' character (ASCII code 38)
 870     return implode('&', $pairs);
 871   }
 872 }
 873
 874 ?>