mashape-oauth-js/lib/oauth.js

Library for handling OAuth (1.0a, Echo, XAuth, and 2.0) Requests and Responses

var crypto = require('crypto');
var http = require('http');
var https = require('https');
var Url = require('url');
var query = require('querystring');
var utils = require('./utils');
var zlib = require('zlib');
var fs = require('fs')
var requestApi = require('request')
var FormData = require('form-data')

// Constructor for starting an OAuth (1.0) handshake
//
// - `options` `Object` *OAuth request options*
//   - `echo` `Object` ___Optional___ *If it exists we treat the request as OAuth Echo request. See [Twitter](https://dev.twitter.com/docs/auth/oauth/oauth-echo)*
//       - `verifyCredentials` `String` *What is the credentials URI to delegate against?*
//   - `realm` `String` ___Optional___ *Access Authentication Framework Realm Value, Commonly used in Echo Requests, allowed in all however: [Section 3.5.1](http://tools.ietf.org/html/rfc5849#section-3.5.1)*
//   - `requestUrl` `String` *Request Token URL. [Section 6.1](http://oauth.net/core/1.0/#auth_step1)*
//   - `accessUrl` `String` *Access Token URL. [Section 6.2](http://oauth.net/core/1.0/#auth_step2)*
//   - `callback` `String` *URL the Service Provider will use to redirect User back to Consumer after obtaining User Authorization has been completed. [Section 6.2.1](http://oauth.net/core/1.0/#auth_step2)*
//   - `consumerKey` `String` *The Consumer Key*
//   - `consumerSecret` `String` *The Consumer Secret*
//   - `version` `String` ___Optional___ *By spec this is `1.0` by default. [Section 6.3.1](http://oauth.net/core/1.0/#auth_step3)*
//   - `signatureMethod` `String` *Type of signature to generate, must be one of:*
//       - PLAINTEXT
//       - RSA-SHA1
//       - HMAC-SHA1
//   - `nonceLength` `Number` ___Optional___ *Length of nonce string. Default `32`*
//   - `headers` `Object` ___Optional___ *Headers to be sent along with request, by default these are already set.*
//   - `clientOptions` `Object` ___Optional___ *Contains `requestTokenHttpMethod` and `accessTokenHttpMethod` value.*
//   - `parameterSeperator` `String` ___Optional___ *Seperator for OAuth header parameters. Default is `,`*
//
// Example: (javascript)
//
//     var OAuth = require('mashape-oauth').OAuth;
//     var oa = new OAuth({ /* ... options ... */ }, callback);
//
var OAuth = module.exports = exports = function (options) {
  options = options || {};

  if (options.echo) {
    this.echo = true;
    this.verifyCredentials = options.echo.verifyCredentials;
  } else {
    this.echo = false;
    this.requestUrl = options.requestUrl;
    this.accessUrl = options.accessUrl;
    this.authorizeCallback = options.callback ? options.callback : "oob";
  }

  this.realm = options.realm || undefined;
  this.consumerKey = options.consumerKey;
  this.consumerSecret = utils.encodeData(options.consumerSecret);
  this.version = options.version || "1.0";
  this.signatureMethod = typeof options.signatureMethod === 'string' ? options.signatureMethod.toUpperCase() : undefined;
  this.nonceLength = options.nonceLength || options.nonceSize || 32;
  this.customTimestamp = options.timestamp || undefined;
  this.customNonce = options.nonce || undefined;

  if (this.signatureMethod !== OAuth.signatures.plaintext &&
    this.signatureMethod !== OAuth.signatures.hmac &&
    this.signatureMethod !== OAuth.signatures.rsa) {
    throw new Error("Un-supported signature method: " + this.signatureMethod);
  }

  if (this.signatureMethod === OAuth.signatures.rsa) {
    this.privateKey = options.consumerSecret;
  }

  this.headers = options.headers || {
      "Accept": "*/*",
      "Connection": "close",
      "User-Agent": "Gatekeeper-OAUTH"
    };

  this.clientOptions = options.clientOptions || {
      "requestTokenHttpMethod": "POST",
      "accessTokenHttpMethod": "POST"
    };

  this._clientOptions = this.clientOptions;
  this.parameterSeperator = options.parameterSeperator || ",";
};

OAuth.prototype.setClientOptions = function (options) {
  this.clientOptions = utils.extend(this._clientOptions, options);
};

// OAuth 1.0 Signature Enum
OAuth.signatures = {
  plaintext: "PLAINTEXT",
  hmac: "HMAC-SHA1",
  rsa: "RSA-SHA1"
};

// Calculates current timestamp in seconds.
// Utilizes flooring to prevent being sent too soon.
OAuth.getTimestamp = function () {
  return Math.floor((new Date()).getTime() / 1000);
};

// Generates randomized string of a certain length given a character table.
//
// - `length` `Number` ___Optional___ *Size of string in character length. Default `32`*
//
// Example: (javascript)
//
//    var nonce = OAuth.nonce();
//
OAuth.nonce = function (length) {
  var result = [];
  var i = 0;

  length = length || 32;

  for (i; i < length; i++) {
    result.push(OAuth.nonce.chars[Math.floor(Math.random() * OAuth.nonce.chars.length)]);
  }

  return result.join('');
};

// Nonce Character Table.
// By Default this character table is `a-zA-Z0-9`.
OAuth.nonce.chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';

// Sorts tuple array by key (0), then value (1) when keys (0) are equal (non-strict).
//
// - `tuple` `Array`
//
// Return: `Array`
OAuth.tupleSorter = function (tuple) {
  tuple.sort(function (a, b) {
    if (a[0] == b[0]) return a[1] < b[1] ? -1 : 1;
    else return a[0] < b[0] ? -1 : 1;
  });

  return tuple;
};

// Takes an object of key-value store and converts each item into a tuple.
// If they value of a key is an array we iterate upon it creating multiple tuples of that key.
//
// Example: (javascript)
//
//     // Would become: [["hello", "world"], ["name", "woah"], ["array", 1], ["array", 2], ["array", 3]];
//     var tuple = OAuth.tupleArguments({ "hello": "world", "name": "woah", "array": [1,2,3] });
//
// Return: `Array`
OAuth.tupleArguments = function (args) {
  var tuple = [];
  var i = 0;
  var key;
  var value;

  for (key in args) {
    if (!args.hasOwnProperty(key)) continue;
    value = args[key];

    if (Array.isArray(value)) {
      for (i; i < value.length; i++) {
        tuple.push([key, value[i]]);
      }
    } else {
      tuple.push([key, value]);
    }
  }

  return tuple;
};

// Normalizes argument object. First by tupling, encoding & sorting the tuples, and
// finally creating a psuedo-query string of key-value information from the tupled array.
//
// Example: (javascript)
//
//     // Would become: array=1&array=2&array=3&hello=world&name=woah
//     var tuple = OAuth.tupleArguments({ "hello": "world", "name": "woah", "array": [1,2,3] });
//
// Return: `String`
OAuth.normalizeArguments = function (args) {
  var tuple = OAuth.tupleArguments(args);
  var output = "";
  var i = 0;

  for (i; i < tuple.length; i++) {
    tuple[i][0] = utils.encodeData(tuple[i][0]);
    tuple[i][1] = utils.encodeData(tuple[i][1]);
  }

  tuple = OAuth.tupleSorter(tuple);

  for (i = 0; i < tuple.length; i++) {
    output += tuple[i][0] + "=" + tuple[i][1] + ((i < tuple.length-1) ? "&" : "");
  }

  return output;
};

// Formats and normalizes url port, protocol and slashes.
//
// - `url` `String` URL to be normalized
//
// Return: `String`
OAuth.normalizeUrl = function (url) {
  var parsed = Url.parse(url, true);
  var port = "";

  if (parsed.port) {
    if ((parsed.protocol === 'http:' && parsed.port !== '80') || (parsed.protocol === 'https:' && parsed.port !== '443')) {
      port = ":" + parsed.port;
    }
  }

  return parsed.protocol + "//" + parsed.hostname + port + ((!parsed.pathname || parsed.pathname === "") ? "/" : parsed.pathname);
};

// Details whether given parameter is a direct oauth parameter or not.
// We can tell this by checking whether the parameter begins with `oauth_` or not.
//
// - `parameter` `String` *Parameter name or key name*
//
// Return: `Boolean`
OAuth.isOAuthParameter = function (parameter) {
  var match = parameter.match('^oauth_');
  return (match && (match[0] === "oauth_"));
};

// Generates signature by creating the signature base first then delegating the information to `createSignature`.
//
// Return: `String`
OAuth.prototype.getSignature = function (options) {
  return this.createSignature(this.createSignatureBase(options.method, options.url, options.parameters), options.token_secret);
};

// Encodes and normalizes url, parameters, then joins them together with the `&` char, in ordinance of arguments.
//
// - `method` `String` *Request method*
// - `url` `String` *URL being utilized in request*
// - `parameters` `String` *Tupled, encoded and normalized parameters list*
//
// Return: `String`
OAuth.prototype.createSignatureBase = function (method, url, parameters) {
  url = utils.encodeData(OAuth.normalizeUrl(url));
  parameters = utils.encodeData(parameters);
  return method.toUpperCase() + "&" + url + "&" + parameters;
};

// Generates signature by hashing against the base using a key made up of the consumer secret and token secret.
//
// - `base` `String` *Joint string, made up of request method, url, and parameters.*
// - `token_secret` `String`
//
// Return: `String`
OAuth.prototype.createSignature = function (base, token_secret) {
  token_secret = (token_secret === undefined) ? "" : utils.encodeData(token_secret);
  var key = this.consumerSecret + "&" + token_secret;

  if (this.signatureMethod === OAuth.signatures.plaintext) {
    return key;
  } else if (this.signatureMethod === OAuth.signatures.rsa) {
    return crypto.createSign("RSA-SHA1").update(base).sign(this.privateKey || "", 'base64');
  } else if (crypto.Hmac) {
    return crypto.createHmac("sha1", key).update(base).digest('base64');
  } else {
    return utils.SHA1.hmacSha1(key, base);
  }
};

OAuth.prototype.createClient = function (options) {
  return ((options.ssl) ? https : http).request(options);
};

OAuth.prototype.buildAuthorizationHeaders = function (parameters) {
  var header = 'OAuth ';
  var realm;
  var i = 0;

  for (i; i < parameters.length; i++) {
    if (parameters[i][0] === "realm") {
      realm = parameters[i][1];
    }
  }

  if (realm || this.realm) {
    header += 'realm="' + (realm || this.realm) + '",';
  }

  for (i = 0; i < parameters.length; i++) {
    if (OAuth.isOAuthParameter(parameters[i][0])) {
      header += '' + utils.encodeData(parameters[i][0]) + '="' + utils.encodeData(parameters[i][1]) + '"' + this.parameterSeperator;
    }
  }

  return header.substring(0, header.length - this.parameterSeperator.length);
};

OAuth.prototype.buildAuthorizationQuery = function (parameters) {
  var query = "", realm, i = 0;

  for (i; i < parameters.length; i++) {
    if (parameters[i][0] === "realm") {
      realm = parameters[i][1];
    }
  }

  if (realm || this.realm) {
    query += 'realm=' + (realm || this.realm) + '&';
  }

  for (i = 0; i < parameters.length; i++) {
    query += utils.encodeData(parameters[i][0]) + '=' + utils.encodeData(parameters[i][1]) + '&';
  }

  return query.substring(0, query.length-1);
};

OAuth.prototype.prepareParameters = function (options) {
  var parameters = {};
  var signature = {};
  var parsed;
  var key;
  var extras;
  var sorted;

  if (typeof options.oauth_body_hash === "string") {
    parameters.oauth_body_hash = options.oauth_body_hash;
  } else {
    if (typeof options.body === "string") {
      try {
        parameters = JSON.parse(options.body);
      } catch (e) {
        if (options.type.toLowerCase() === "application/x-www-form-urlencoded" && typeof query.parse(options.body) === "object") {
          parameters = utils.extend(parameters, query.parse(options.body));
        }
      }
    }
  }

  parameters.oauth_timestamp = typeof this.customTimestamp === 'function' ? this.customTimestamp() : OAuth.getTimestamp();
  parameters.oauth_nonce = typeof this.customNonce === 'function' ? this.customNonce(this.nonceLength) : OAuth.nonce(this.nonceLength);
  parameters.oauth_version = this.version;
  parameters.oauth_signature_method = this.signatureMethod;
  parameters.oauth_consumer_key = this.consumerKey;

  if (typeof options.oauth_token !== 'undefined') {
    parameters.oauth_token = options.oauth_token;
  }

  if (this.echo) {
    signature = {
      method: "GET",
      url: this.verifyCredentials,
      parameters: OAuth.normalizeArguments(parameters)
    };
  } else {
    if (options.parameters) {
      for (key in options.parameters) {
        if (options.parameters.hasOwnProperty(key)) {
          parameters[key] = options.parameters[key];
        }
      }
    }

    parsed = Url.parse(options.url, false);

    if (parsed.query) {
      extras = query.parse(parsed.query);
      parameters = utils.serialExtend(parameters, extras);
    }

    signature = {
      method: options.method,
      url: options.url,
      parameters: OAuth.normalizeArguments(parameters)
    };
  }

  if (options.oauth_token_secret || options.token_secret) {
    signature.token_secret = options.oauth_token_secret || options.token_secret;
  }

  sorted = OAuth.tupleSorter(OAuth.tupleArguments(parameters));
  sorted.push(["oauth_signature", this.getSignature(signature)]);

  return sorted;
};

// Correctly handles and parses information required for an OAuth Request
//
// - `options` `Object`
//    - `oauth_token` `String` ___Required___
//    - `oauth_token_secret` `String` ___Required___
//    - `type` `String` *Content Type*
//    - `method` `String` *Request Method Type*
//    - `realm` `String` *Realm for Echo request or basic request*
//    - `url` `String` *Request location*
//    - `parameters` `Object` *Extra parameters for body*
//    - `body` `Mixed`
//    - `oauth_body_hash` `String` *OAuth body hash for signature.*
//    - `agent` `Object` *Agent for tunneling*
//
// The following options from tls.connect() can also be specified, however
// globalAgent will silently ignore these.
//
//    - `pfx` Certificate, Private key and CA certificates to use for SSL. Default null.
//    - `key` Private key to use for SSL. Default null.
//    - `passphrase` A string of passphrase for the private key or pfx. Default null.
//    - `cert` Public x509 certificate to use. Default null.
//    - `ca` An authority certificate or array of authority certificates to check the remote host against.
//    - `ciphers` A string describing the ciphers to use or exclude. Consult http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT for details on the format.
//    - `rejectUnauthorized` If true, the server certificate is verified against the list of supplied CAs. An 'error' event is emitted if verification fails. Verification happens at the connection level, before the HTTP request is sent. Default true.
//    - `secureProtocol` The SSL method to use, e.g. TLSv1_method to force TLS version 1. The possible values depend on your installation of OpenSSL and are defined in the constant SSL_METHODS.
OAuth.prototype.performSecureRequest = function (options, callback) {
  var self = this;
  var settings = {};
  var headers = {};
  var type = false;
  var sorted;
  var parsed;
  var data;
  var request;
  var key;
  var path;

  options.method = options.method.toUpperCase();
  options.realm = options.realm || this.realm || undefined;
  callback = callback || options.callback;
  sorted = this.prepareParameters(options);
  parsed = Url.parse(options.url, false);
  parsed.port = parsed.port || (parsed.protocol === 'http:' ? 80 : 443);

  if (this.echo) {
    headers["X-Auth-Service-Provider"] = this.verifyCredentials;
  }

  headers[(this.echo) ? "X-Verify-Credentials-Authorization" : "Authorization"] = this.buildAuthorizationHeaders(sorted);
  headers.Host = parsed.host;
  headers = utils.extend(headers, this.headers);

  // Filter out any extra parameters that deal with OAuth
  for (key in options.parameters) {
    if (options.parameters.hasOwnProperty(key)) {
      if (OAuth.isOAuthParameter(key)) {
        delete options.parameters[key];
      }
    }
  }

  // Fixes mismatch between query.stringify and this.encodeData
  if ((options.method !== "GET") && (!options.body && options.parameters)) {
    options.body = query.stringify(options.parameters).
    replace(/\!/g, "%21").
    replace(/\'/g, "%27").
    replace(/\(/g, "%28").
    replace(/\)/g, "%29").
    replace(/\*/g, "%2A");
  }

  if (this.clientOptions.accessTokenHttpMethod === 'GET' && options.url === this.accessUrl) {
    delete headers.Authorization;
    parsed.query = this.buildAuthorizationQuery(sorted);
  }

  // Prevent setting default content-type for methods that generally disallow
  // it to appease APIs such as JIRA.
  if ((options.method !== "GET") && !options.type) {
    options.type = "application/x-www-form-urlencoded";
  }

  if (options.type) {
    headers["Content-Type"] = options.type;
  }

  // Deal multipart/form-data
  if (options.body && options.type === "multipart/form-data") {
    var form = {}
    for(var key in options.body) {
      if(options.body.hasOwnProperty(key)) {
        if(typeof options.body[key] === 'object' && options.body[key].path) {
          form[key] = fs.createReadStream(options.body[key].path)
        } else {
          form[key] = options.body[key]
        }
      }
    }

    delete headers["Content-Type"]

    requestApi.post({
      url: options.url,
      formData: form,
      headers: headers
    }, function optionalCallback(err, httpResponse, body) {
      if (err) {
        return console.error('upload failed:', err);
      }
      callback(null, body)
    })
    return
  }

  headers["Content-Length"] = options.body ? Buffer.isBuffer(options.body) ? options.body.length :  Buffer.byteLength(options.body) : 0;

  if (!parsed.pathname || parsed.pathname === "") {
    parsed.pathname = "/";
  }

  path = parsed.query ? parsed.pathname + "?" + parsed.query : parsed.pathname;
  settings = {
    port: parsed.port,
    host: parsed.hostname,
    path: path,
    method: options.method,
    headers: headers,
    ssl: (parsed.protocol === 'https:'),
    agent: options.agent
  };

  // Allow for tls.connect options
  // https://nodejs.org/api/https.html#https_https_request_options_callback
  if (settings.ssl) {
    settings.pfx = options.pfx;
    settings.key = options.key;
    settings.cert = options.cert;

    if (typeof options.ca !== 'undefined') {
      settings.ca = options.ca;
    }

    if (typeof options.ciphers !== 'undefined') {
      settings.ciphers = options.ciphers;
    }

    if (typeof options.rejectUnauthorized !== 'undefined') {
      settings.rejectUnauthorized = options.rejectUnauthorized;
    }

    if (typeof options.secureProtocol !== 'undefined') {
      settings.secureProtocol = options.secureProtocol;
    }
  }

  request = this.createClient({
    port: parsed.port,
    host: parsed.hostname,
    path: path,
    method: options.method,
    headers: headers,
    ssl: (parsed.protocol === 'https:')
  });

  if (callback) {
    var earlyClose = utils.isAnEarlyCloseHost(parsed.hostname);
    var called = false;

    var respond = function (response) {
      if (type === 2) {
        data = data.toString('utf8');
      }

      if (called) {
        return;
      } else {
        called = true;
      }

      if (response.statusCode >= 200 && response.statusCode <= 299) {
        callback(null, data, response);
      } else if ((response.statusCode === 301 || response.statusCode === 302) && response.headers && response.headers.location) {
        options.url = response.headers.location;
        self.performSecureRequest(options, callback);
      } else {
        callback({
          statusCode: response.statusCode,
          data: data
        }, data, response);
      }
    };

    request.on('response', function (response) {
      var output;

      if (self.clientOptions.detectResponseContentType && utils.isBinaryContent(response)) {
        data = new Buffer(0);
        type = 1;
        output = response;
      } else if (response.headers['content-encoding'] === 'gzip') {
        var gunzip = zlib.createGunzip();
        data = new Buffer(0);
        type = 2;
        response.pipe(gunzip);
        output = gunzip;
      } else {
        response.setEncoding('utf8');
        data = "";
        output = response;
      }

      output.on('data', function (chunk) {
        if (type === 1 || type === 2) {
          data = Buffer.concat([data, chunk]);
        } else {
          data += chunk;
        }
      });

      output.on('close', function () {
        if (earlyClose) {
          respond(response);
        }
      });

      output.on('end', function () {
        respond(response);
      });
    });

    request.on('error', function (error) {
      called = true;
      callback(error);
    });

    if ((options.method !== "GET") && (options.body && options.body !== "")) {
      request.write(options.body);
    }

    request.end();

    return;
  }

  if ((options.method !== "GET") && (options.body && options.body !== "")) {
    request.write(options.body);
  }

  return request;
};

// Sugar for #performSecureRequest
OAuth.prototype.handleRequest = function (options, callback) {
  return this.performSecureRequest(options, callback);
};

// Backwards compatability
// Deprecated in favor of #handleRequest
OAuth.prototype.handleRequestLong = function (url, method, token, secret, body, type, parameters, callback) {
  if (typeof type === 'function') {
    callback = type;
    type = undefined;
    parameters = undefined;
  } else if (typeof parameters === 'function') {
    callback = parameters;
    parameters = undefined;
  }

  return this.handleRequest({
    url: url,
    method: method,
    oauth_token: token || undefined,
    oauth_token_secret: secret,
    body: body,
    type: type,
    parameters: parameters
  }, callback);
};

// Generates sugar verb methods for creating requests.
[ 'delete', 'put', 'post', 'get', 'patch' ].forEach(function (k) {
  OAuth.prototype[k] = function (url, token, secret, body, type, parameters, callback) {
    if (typeof token === 'function' || typeof url === 'object') {
      url.method = k.toUpperCase();
      return this.handleRequest(url, token);
    }

    return this.handleRequestLong(url, k.toUpperCase(), token, secret, body, type, parameters, callback);
  };
});

// Create & handles Access Token call while extracting information from response such as Token and Secret.
//
// - `options` `Object`
//   - `oauth_verifier` `String` *Verification code tied to the Request Token. [Section 2.3](http://tools.ietf.org/html/rfc5849#section-2.3)*
//   - `oauth_token` `String` *Request Token*
//   - `oauth_token_secret` `String` *Request Token Secret, used to help generation of signatures.*
//   - `parameters` `Object` ___Optional___ *Additional headers to be sent along with request.*
//   - `callback` `Function` ___Optional___ *Method to be invoked upon result, over-ridden by argument if set.*
// - `callback` `Function` *Anonymous Function to be invoked upon response or failure, setting this overrides previously set callback inside options object.*
//
// Example: (javascript)
//
//     oa.getOAuthRequestToken({/* ... Parameters ... */}, callback);
//
OAuth.prototype.getOAuthAccessToken = function (options, callback) {
  callback = options.callback || callback;
  options.parameters = options.parameters || {};

  if (options.oauth_verifier) {
    options.parameters.oauth_verifier = options.oauth_verifier;
    delete options.oauth_verifier;
  }

  options.method = this.clientOptions.accessTokenHttpMethod;
  options.url = this.accessUrl;
  options.body = null;
  options.type = null;

  this.performSecureRequest(options, function (error, data) {
    if (error) {
      return callback(error);
    }

    var results = query.parse(data);
    var token = results.oauth_token;
    var secret = results.oauth_token_secret;

    delete results.oauth_token;
    delete results.oauth_token_secret;

    callback(null, token, secret, results);
  });
};

// Create & handles Request Token call while extracting information from response such as Token and Secret.
//
// - `parameters` `Object` ___Optional___ *Additional Headers you might want to pass along.*
//   - *If omitted, you can treat parameters argument as callback and pass along a function as a single parameter.*
// - `callback` `Function` *Anonymous Function to be invoked upon response or failure.*
//
// Example: (javascript)
//
//     oa.getOAuthRequestToken({/* ... Parameters ... */}, callback);
//
OAuth.prototype.getOAuthRequestToken = function (parameters, callback) {
  if (typeof parameters === 'function') {
    callback = parameters;
    parameters = {};
  }

  if (this.authorizeCallback) {
    parameters.oauth_callback = this.authorizeCallback;
  }

  this.handleRequestLong(this.requestUrl, this.clientOptions.requestTokenHttpMethod, null, null, null, null, parameters, function (error, data) {
    if (error) {
      return callback(error);
    }

    var results = query.parse(data);
    var token = results.oauth_token;
    var secret = results.oauth_token_secret;

    delete results.oauth_token;
    delete results.oauth_token_secret;

    callback(null, token, secret, results);
  });
};

OAuth.prototype.getXAuthAccessToken = function (username, password, permissions, callback) {
  if (typeof permissions === 'function') {
    callback = permissions;
    permissions = undefined;
  }

  var parameters = {
    'x_auth_mode': 'client_auth',
    'x_auth_password': password,
    'x_auth_username': username
  };

  if (permissions) {
    parameters.x_auth_permission = permissions;
  }

  this.handleRequestLong(this.accessUrl, this.clientOptions.accessTokenHttpMethod, null, null, null, null, parameters, function (error, data) {
    if (error) {
      return callback(error);
    }

    var results = query.parse(data);
    var token = results.oauth_token;
    var secret = results.oauth_token_secret;

    delete results.oauth_token;
    delete results.oauth_token_secret;

    callback(null, token, secret, results);
  });
};

OAuth.prototype.signUrl = function (url, token, secret, method) {
  var parsed = Url.parse(url, false);
  var query = "";
  var i = 0;
  var ordered;

  ordered = this.prepareParameters({
    url: url,
    oauth_token: token,
    oauth_token_secret: secret,
    method: method || "GET"
  });

  for (i; i < ordered.length; i++) {
    query += ordered[i][0] + "=" + utils.encodeData(ordered[i][1]) + "&";
  }

  return parsed.protocol + "//" + parsed.host + parsed.pathname + "?" + query.substring(0, query.length-1);
};

OAuth.prototype.authHeader = function (options) {
  if (typeof arguments[1] !== 'undefined') {
    options = {
      url: options,
      token: arguments[1],
      secret: arguments[2],
      method: arguments[3],
      body: arguments[4]
    };
  }

  return this.buildAuthorizationHeaders(this.prepareParameters({
    url: options.url,
    oauth_token: options.token,
    oauth_token_secret: options.secret,
    method: options.method || "GET",
    body: options.body
  }));
};