<?php
// vim: foldmethod=marker

/* Generic exception class
 */
class W3tcOAuthException extends Exception {
  // pass
}


class W3tcOAuthConsumer {
  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 W3tcOAuthToken {
  // 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=" .
           W3tcOAuthUtil::urlencode_rfc3986($this->key) .
           "&oauth_token_secret=" .
           W3tcOAuthUtil::urlencode_rfc3986($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 W3tcOAuthSignatureMethod {
  /**
   * 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 W3tcOAuthRequest $request
   * @param W3tcOAuthConsumer $consumer
   * @param W3tcOAuthToken $token
   * @return string
   */
  abstract public function build_signature($request, $consumer, $token);

  /**
   * Verifies that a given signature is correct
   * @param W3tcOAuthRequest $request
   * @param W3tcOAuthConsumer $consumer
   * @param W3tcOAuthToken $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 W3tcOAuthSignatureMethod_HMAC_SHA1 extends W3tcOAuthSignatureMethod {
  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 : ""
    );

    $key_parts = W3tcOAuthUtil::urlencode_rfc3986($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 W3tcOAuthSignatureMethod_PLAINTEXT extends W3tcOAuthSignatureMethod {
  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 : ""
    );

    $key_parts = W3tcOAuthUtil::urlencode_rfc3986($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 W3tcOAuthSignatureMethod_RSA_SHA1 extends W3tcOAuthSignatureMethod {
  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 W3tcOAuthRequest {
  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();
    $parameters = array_merge( W3tcOAuthUtil::parse_parameters(parse_url($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 = W3tcOAuthUtil::get_headers();

      // Parse the query-string to find GET parameters
      $parameters = W3tcOAuthUtil::parse_parameters($_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')
          ) {
        $post_data = W3tcOAuthUtil::parse_parameters(
          file_get_contents(self::$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 = W3tcOAuthUtil::split_header(
          $request_headers['Authorization']
        );
        $parameters = array_merge($parameters, $header_parameters);
      }

    }

    return new W3tcOAuthRequest($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();
    $defaults = array("oauth_version" => W3tcOAuthRequest::$version,
                      "oauth_nonce" => W3tcOAuthRequest::generate_nonce(),
                      "oauth_timestamp" => W3tcOAuthRequest::generate_timestamp(),
                      "oauth_consumer_key" => $consumer->key);
    if ($token)
      $defaults['oauth_token'] = $token->key;

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

    return new W3tcOAuthRequest($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 W3tcOAuthUtil::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()
    );

    $parts = W3tcOAuthUtil::urlencode_rfc3986($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 W3tcOAuthUtil::build_http_query($this->parameters);
  }

  /**
   * builds the Authorization: header
   */
  public function to_header($realm=null) {
    $first = true;
	if($realm) {
      $out = 'Authorization: OAuth realm="' . W3tcOAuthUtil::urlencode_rfc3986($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 W3tcOAuthException('Arrays not supported in headers');
      }
      $out .= ($first) ? ' ' : ',';
      $out .= W3tcOAuthUtil::urlencode_rfc3986($k) .
              '="' .
              W3tcOAuthUtil::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 W3tcOAuthUtil {
  public static function urlencode_rfc3986($input) {
  if (is_array($input)) {
    return array_map(array('W3tcOAuthUtil', '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] = W3tcOAuthUtil::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);
      $parameter = W3tcOAuthUtil::urldecode_rfc3986($split[0]);
      $value = isset($split[1]) ? W3tcOAuthUtil::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
    $keys = W3tcOAuthUtil::urlencode_rfc3986(array_keys($params));
    $values = W3tcOAuthUtil::urlencode_rfc3986(array_values($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);
  }
}
