http_socket_oauth.php

<?php
App::import('Core', 'HttpSocket');

/**
 * Extension to CakePHP core HttpSocket class that overrides the request method
 * and intercepts requests whose $request['auth']['method'] param is 'OAuth'.
 *
 * The correct OAuth Authorization header is determined from the request params
 * and then set in the $request['header']['Authorization'] param of the request
 * array before passing it back to HttpSocket::request() to send the request and
 * parse the response.
 *
 * So to trigger OAuth, add $request['auth']['method'] = 'OAuth' to your
 * request. In addition, you'll need to add your consumer key in the
 * $request['auth']['oauth_consumer_key'] and your consumer secret in the
 * $request['auth']['oauth_consumer_secret'] param. These are given to you by
 * the OAuth provider. And once you have them, $request['auth']['oauth_token']
 * and $request['auth']['oauth_token_secret'] params. Your OAuth provider may
 * require you to send additional params too. Include them in the
 * $request['auth'] array and they'll be passed on in the Authorization header
 * and considered when signing the request.
 *
 * @author Neil Crookes <neil@neilcrookes.com>
 * @link http://www.neilcrookes.com
 * @copyright (c) 2010 Neil Crookes
 * @license MIT License - http://www.opensource.org/licenses/mit-license.php
 */
class HttpSocketOauth extends HttpSocket {

  /**
   * Default OAuth parameters. These get merged into the $request['auth'] param.
   *
   * @var array
   */
	var $defaults = array(
    'oauth_version' => '1.0',
    'oauth_signature_method' => 'HMAC-SHA1',
  );

  /**
   * Overrides HttpSocket::request() to handle cases where
   * $request['auth']['method'] is 'OAuth'.
   *
   * @param array $request As required by HttpSocket::request(). NOTE ONLY
   *   THE ARRAY TYPE OF REQUEST IS SUPPORTED
   * @return array
   */
  function request($request = array()) {

    // If the request does not need OAuth Authorization header, let the parent
    // deal with it.
    if (!isset($request['auth']['method']) || $request['auth']['method'] != 'OAuth') {
      return parent::request($request);
    }

    // Generate the OAuth Authorization Header content for this request from the
    // request data and add it into the request's Authorization Header. Note, we
    // don't just add the header directly in the request variable and return the
    // whole thing from the authorizationHeader() method because in some cases
    // we may not want the authorization header content in the request's
    // authorization header, for example, OAuth Echo as used by Twitpic and
    // Twitter includes an Authorization Header as required by twitter's verify
    // credentials API in the X-Verify-Credentials-Authorization header.
    $request['header']['Authorization'] = $this->authorizationHeader($request);

    // Now the Authorization header is built, fire the request off to the parent
    // HttpSocket class request method that we intercepted earlier.
    return parent::request($request);

  }

  /**
   * Returns the OAuth Authorization Header string for a given request array.
   *
   * This method is called by request but can also be called directly, which is
   * useful if you need to get the OAuth Authorization Header string, such as
   * when integrating with a service that uses OAuth Echo (Authorization
   * Delegation) e.g. Twitpic. In this case you send a normal unauthenticated
   * request to the service e.g. Twitpic along with 2 extra headers:
   * - X-Auth-Service-Provider - effectively, this is the realm that identity
   *   delegation should be sent to - in the case of Twitter, just set this to
   *   https://api.twitter.com/1/account/verify_credentials.json;
   * - X-Verify-Credentials-Authorization - Consumer should create all the OAuth
   *   parameters necessary so it could call
   *   https://api.twitter.com/1/account/verify_credentials.json using OAuth in
   *   the HTTP header (e.g. it should look like OAuth oauth_consumer_key="...",
   *   oauth_token="...", oauth_signature_method="...", oauth_signature="...",
   *   oauth_timestamp="...", oauth_nonce="...", oauth_version="...".
   * 
   * @param array $request As required by HttpSocket::request(). NOTE ONLY
   *   THE ARRAY TYPE OF REQUEST IS SUPPORTED
   * @return String
   */
  function authorizationHeader($request) {

    $request['auth'] = array_merge($this->defaults, $request['auth']);

    // Nonce, or number used once is used to distinguish between different
    // requests to the OAuth provider
    if (!isset($request['auth']['oauth_nonce'])) {
      $request['auth']['oauth_nonce'] = md5(uniqid(rand(), true));
    }

    if (!isset($request['auth']['oauth_timestamp'])) {
      $request['auth']['oauth_timestamp'] = time();
    }

    // Now starts the process of signing the request. The signature is a hash of
    // a signature base string with the secret keys. The signature base string
    // is made up of the request http verb, the request uri and the request
    // params, and the secret keys are the consumer secret (for your
    // application) and the access token secret generated for the user by the
    // provider, e.g. twitter, when the user authorizes your app to access their
    // details.

    // Building the request uri, note we don't include the query string or
    // fragment. Standard ports must not be included but non standard ones must.
    $uriFormat = '%scheme://%host';
    if (isset($request['uri']['port']) && !in_array($request['uri']['port'], array(80, 443))) {
      $uriFormat .= ':' . $request['uri']['port'];
    }
    $uriFormat .= '/%path';
    if (strpos(Configure::version(), "1.2") === 0) {
	$requestUrl = $this->buildUri($request['uri'], $uriFormat);
    } else {
	$requestUrl = $this->_buildUri($request['uri'], $uriFormat);
    }

    // OAuth reference states that the request params, i.e. oauth_ params, body
    // params and query string params need to be normalised, i.e. combined in a
    // single string, separated by '&' in the format name=value. But they also
    // need to be sorted by key, then by value. You can't just merge the auth,
    // body and query arrays together then do a ksort because there may be
    // parameters with the same name. Instead we've got to get them into an
    // array of array('name' => '<name>', 'value' => '<value>') elements, then
    // sort those elements.

    // Let's start with the auth params - however, we shouldn't include the auth
    // method (OAuth), and OAuth reference says not to include the realm or the
    // consumer or token secrets
    $requestParams = $this->assocToNumericNameValue(array_diff_key(
      $request['auth'],
      array_flip(array('realm', 'method', 'oauth_consumer_secret', 'oauth_token_secret'))
    ));

    // Next add the body params if there are any and the content type header is
    // not set, or it's application/x-www-form-urlencoded
    if (isset($request['body']) && (!isset($request['header']['Content-Type']) || stristr($request['header']['Content-Type'], 'application/x-www-form-urlencoded'))) {
      $requestParams = array_merge($requestParams, $this->assocToNumericNameValue($request['body']));
    }

    // Finally the query params
    if (isset($request['uri']['query'])) {
      $requestParams = array_merge($requestParams, $this->assocToNumericNameValue($request['uri']['query']));
    }

    // Now we can sort them by name then value
    usort($requestParams, array($this, 'sortByNameThenByValue'));

    // Now we concatenate them together in name=value pairs separated by &
    $normalisedRequestParams = '';
    foreach ($requestParams as $k => $requestParam) {
      if ($k) {
        $normalisedRequestParams .= '&';
      }
      $normalisedRequestParams .= $requestParam['name'] . '=' . $this->parameterEncode($requestParam['value']);
    }

    // The signature base string consists of the request method (uppercased) and
    // concatenated with the request URL and normalised request parameters
    // string, both encoded, and separated by &
    $signatureBaseString = strtoupper($request['method']) . '&'
                         . $this->parameterEncode($requestUrl) . '&'
                         . $this->parameterEncode($normalisedRequestParams);

    // The signature base string is hashed with a key which is the consumer
    // secret (assigned to your application by the provider) and the token
    // secret (also known as the access token secret, if you've got it yet),
    // both encoded and separated by an &
    $key = '';
    if (isset($request['auth']['oauth_consumer_secret'])) {
      $key .= $this->parameterEncode($request['auth']['oauth_consumer_secret']);
    }
    $key .= '&';
    if (isset($request['auth']['oauth_token_secret'])) {
      $key .= $this->parameterEncode($request['auth']['oauth_token_secret']);
    }

    // Finally construct the signature according to the value of the
    // oauth_signature_method auth param in the request array.
    switch ($request['auth']['oauth_signature_method']) {
      case 'HMAC-SHA1':
        $request['auth']['oauth_signature'] = base64_encode(hash_hmac('sha1', $signatureBaseString, $key, true));
        break;
      default:
        // @todo implement the other 2 hashing methods
        break;
    }

    // Finally, we have all the Authorization header parameters so we can build
    // the header string.
    $authorizationHeader = 'OAuth';

    // We don't want to include the realm, method or secrets though
    $authorizationHeaderParams = array_diff_key(
      $request['auth'],
      array_flip(array('method', 'oauth_consumer_secret', 'oauth_token_secret', 'realm'))
    );

    // Add the Authorization header params to the Authorization header string,
    // properly encoded.
    $first = true;

    if (isset($request['auth']['realm'])) {
      $authorizationHeader .= ' realm="' . $request['auth']['realm'] . '"';
      $first = false;
    }

    foreach ($authorizationHeaderParams as $name => $value) {
      if (!$first) {
        $authorizationHeader .= ',';
      } else {
        $authorizationHeader .= ' ';
        $first = false;
      }
      $authorizationHeader .= $this->authorizationHeaderParamEncode($name, $value);
    }

    return $authorizationHeader;

  }

  /**
   * Builds an Authorization header param string from the supplied name and
   * value. See below for example:
   *
   * @param string $name E.g. 'oauth_signature_method'
   * @param string $value E.g. 'HMAC-SHA1'
   * @return string E.g. 'oauth_signature_method="HMAC-SHA1"'
   */
  function authorizationHeaderParamEncode($name, $value) {
    return $this->parameterEncode($name) . '="' . $this->parameterEncode($value) . '"';
  }

  /**
   * Converts an associative array of name => value pairs to a numerically
   * indexed array of array('name' => '<name>', 'value' => '<value>') elements.
   *
   * @param array $array Associative array
   * @return array
   */
  function assocToNumericNameValue($array) {
    $return = array();
    foreach ($array as $name => $value) {
      $return[] = array(
        'name' => $name,
        'value' => $value,
      );
    }
    return $return;
  }

  /**
   * User defined function to lexically sort an array of
   * array('name' => '<name>', 'value' => '<value>') elements by the value of
   * the name key, and if they're the same, then by the value of the value key.
   *
   * @param array $a Array with key for 'name' and one for 'value'
   * @param array $b Array with key for 'name' and one for 'value'
   * @return integer 1, 0 or -1 depending on whether a greater than b, less than
   *  or the same.
   */
  function sortByNameThenByValue($a, $b) {
    if ($a['name'] == $b['name']) {
      if ($a['value'] == $b['value']) {
        return 0;
      }
      return ($a['value'] > $b['value']) ? 1 : -1;
    }
    return ($a['name'] > $b['name']) ? 1 : -1;
  }

  /**
   * Encodes paramters as per the OAuth spec by utf 8 encoding the param (if it
   * is not already utf 8 encoded) and then percent encoding it according to
   * RFC3986
   *
   * @param string $param
   * @return string
   */
  function parameterEncode($param) {
    $encoding = mb_detect_encoding($param);
    if ($encoding != 'UTF-8') {
      $param = mb_convert_encoding($param, 'UTF-8', $encoding);
    }
    $param = rawurlencode($param);
    $param = str_replace('%7E', '~', $param);
    return $param;
  }

}
?>