gecko/services/common/hawkclient.js

335 lines
12 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
/*
* HAWK is an HTTP authentication scheme using a message authentication code
* (MAC) algorithm to provide partial HTTP request cryptographic verification.
*
* For details, see: https://github.com/hueniverse/hawk
*
* With HAWK, it is essential that the clocks on clients and server not have an
* absolute delta of greater than one minute, as the HAWK protocol uses
* timestamps to reduce the possibility of replay attacks. However, it is
* likely that some clients' clocks will be more than a little off, especially
* in mobile devices, which would break HAWK-based services (like sync and
* firefox accounts) for those clients.
*
* This library provides a stateful HAWK client that calculates (roughly) the
* clock delta on the client vs the server. The library provides an interface
* for deriving HAWK credentials and making HAWK-authenticated REST requests to
* a single remote server. Therefore, callers who want to interact with
* multiple HAWK services should instantiate one HawkClient per service.
*/
this.EXPORTED_SYMBOLS = ["HawkClient"];
const {interfaces: Ci, utils: Cu} = Components;
Cu.import("resource://services-common/utils.js");
Cu.import("resource://services-crypto/utils.js");
Cu.import("resource://services-common/hawkrequest.js");
Cu.import("resource://services-common/observers.js");
Cu.import("resource://gre/modules/Promise.jsm");
Cu.import("resource://gre/modules/Log.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://gre/modules/Services.jsm");
// log.appender.dump should be one of "Fatal", "Error", "Warn", "Info", "Config",
// "Debug", "Trace" or "All". If none is specified, "Error" will be used by
// default.
// Note however that Sync will also add this log to *its* DumpAppender, so
// in a Sync context it shouldn't be necessary to adjust this - however, that
// also means error logs are likely to be dump'd twice but that's OK.
const PREF_LOG_LEVEL = "services.common.hawk.log.appender.dump";
// A pref that can be set so "sensitive" information (eg, personally
// identifiable info, credentials, etc) will be logged.
const PREF_LOG_SENSITIVE_DETAILS = "services.common.hawk.log.sensitive";
XPCOMUtils.defineLazyGetter(this, "log", function() {
let log = Log.repository.getLogger("Hawk");
// We set the log itself to "debug" and set the level from the preference to
// the appender. This allows other things to send the logs to different
// appenders, while still allowing the pref to control what is seen via dump()
log.level = Log.Level.Debug;
let appender = new Log.DumpAppender();
log.addAppender(appender);
appender.level = Log.Level.Error;
try {
let level =
Services.prefs.getPrefType(PREF_LOG_LEVEL) == Ci.nsIPrefBranch.PREF_STRING
&& Services.prefs.getCharPref(PREF_LOG_LEVEL);
appender.level = Log.Level[level] || Log.Level.Error;
} catch (e) {
log.error(e);
}
return log;
});
// A boolean to indicate if personally identifiable information (or anything
// else sensitive, such as credentials) should be logged.
XPCOMUtils.defineLazyGetter(this, 'logPII', function() {
try {
return Services.prefs.getBoolPref(PREF_LOG_SENSITIVE_DETAILS);
} catch (_) {
return false;
}
});
/*
* A general purpose client for making HAWK authenticated requests to a single
* host. Keeps track of the clock offset between the client and the host for
* computation of the timestamp in the HAWK Authorization header.
*
* Clients should create one HawkClient object per each server they wish to
* interact with.
*
* @param host
* The url of the host
*/
this.HawkClient = function(host) {
this.host = host;
// Clock offset in milliseconds between our client's clock and the date
// reported in responses from our host.
this._localtimeOffsetMsec = 0;
}
this.HawkClient.prototype = {
/*
* Construct an error message for a response. Private.
*
* @param restResponse
* A RESTResponse object from a RESTRequest
*
* @param error
* A string or object describing the error
*/
_constructError: function(restResponse, error) {
let errorObj = {
error: error,
// This object is likely to be JSON.stringify'd, but neither Error()
// objects nor Components.Exception objects do the right thing there,
// so we add a new element which is simply the .toString() version of
// the error object, so it does appear in JSON'd values.
errorString: error.toString(),
message: restResponse.statusText,
code: restResponse.status,
errno: restResponse.status,
toString() {
return this.code + ": " + this.message;
},
};
let retryAfter = restResponse.headers && restResponse.headers["retry-after"];
retryAfter = retryAfter ? parseInt(retryAfter) : retryAfter;
if (retryAfter) {
errorObj.retryAfter = retryAfter;
// and notify observers of the retry interval
if (this.observerPrefix) {
Observers.notify(this.observerPrefix + ":backoff:interval", retryAfter);
}
}
return errorObj;
},
/*
*
* Update clock offset by determining difference from date gives in the (RFC
* 1123) Date header of a server response. Because HAWK tolerates a window
* of one minute of clock skew (so two minutes total since the skew can be
* positive or negative), the simple method of calculating offset here is
* probably good enough. We keep the value in milliseconds to make life
* easier, even though the value will not have millisecond accuracy.
*
* @param dateString
* An RFC 1123 date string (e.g., "Mon, 13 Jan 2014 21:45:06 GMT")
*
* For HAWK clock skew and replay protection, see
* https://github.com/hueniverse/hawk#replay-protection
*/
_updateClockOffset: function(dateString) {
try {
let serverDateMsec = Date.parse(dateString);
this._localtimeOffsetMsec = serverDateMsec - this.now();
log.debug("Clock offset vs " + this.host + ": " + this._localtimeOffsetMsec);
} catch(err) {
log.warn("Bad date header in server response: " + dateString);
}
},
/*
* Get the current clock offset in milliseconds.
*
* The offset is the number of milliseconds that must be added to the client
* clock to make it equal to the server clock. For example, if the client is
* five minutes ahead of the server, the localtimeOffsetMsec will be -300000.
*/
get localtimeOffsetMsec() {
return this._localtimeOffsetMsec;
},
/*
* return current time in milliseconds
*/
now: function() {
return Date.now();
},
/* A general method for sending raw RESTRequest calls authorized using HAWK
*
* @param path
* API endpoint path
* @param method
* The HTTP request method
* @param credentials
* Hawk credentials
* @param payloadObj
* An object that can be encodable as JSON as the payload of the
* request
* @return Promise
* Returns a promise that resolves to the response of the API call,
* or is rejected with an error. If the server response can be parsed
* as JSON and contains an 'error' property, the promise will be
* rejected with this JSON-parsed response.
*/
request: function(path, method, credentials=null, payloadObj={}, retryOK=true) {
method = method.toLowerCase();
let deferred = Promise.defer();
let uri = this.host + path;
let self = this;
function _onComplete(error) {
// |error| can be either a normal caught error or an explicitly created
// Components.Exception() error. Log it now as it might not end up
// correctly in the logs by the time it's passed through _constructError.
if (error) {
log.warn("hawk request error", error);
}
let restResponse = this.response;
let status = restResponse.status;
log.debug("(Response) " + path + ": code: " + status +
" - Status text: " + restResponse.statusText);
if (logPII) {
log.debug("Response text: " + restResponse.body);
}
// All responses may have backoff headers, which are a server-side safety
// valve to allow slowing down clients without hurting performance.
self._maybeNotifyBackoff(restResponse, "x-weave-backoff");
self._maybeNotifyBackoff(restResponse, "x-backoff");
if (error) {
// When things really blow up, reconstruct an error object that follows
// the general format of the server on error responses.
return deferred.reject(self._constructError(restResponse, error));
}
self._updateClockOffset(restResponse.headers["date"]);
if (status === 401 && retryOK && !("retry-after" in restResponse.headers)) {
// Retry once if we were rejected due to a bad timestamp.
// Clock offset is adjusted already in the top of this function.
log.debug("Received 401 for " + path + ": retrying");
return deferred.resolve(
self.request(path, method, credentials, payloadObj, false));
}
// If the server returned a json error message, use it in the rejection
// of the promise.
//
// In the case of a 401, in which we are probably being rejected for a
// bad timestamp, retry exactly once, during which time clock offset will
// be adjusted.
let jsonResponse = {};
try {
jsonResponse = JSON.parse(restResponse.body);
} catch(notJSON) {}
let okResponse = (200 <= status && status < 300);
if (!okResponse || jsonResponse.error) {
if (jsonResponse.error) {
return deferred.reject(jsonResponse);
}
return deferred.reject(self._constructError(restResponse, "Request failed"));
}
// It's up to the caller to know how to decode the response.
// We just return the whole response.
deferred.resolve(this.response);
};
function onComplete(error) {
try {
// |this| is the RESTRequest object and we need to ensure _onComplete
// gets the same one.
_onComplete.call(this, error);
} catch (ex) {
log.error("Unhandled exception processing response:" +
CommonUtils.exceptionStr(ex));
deferred.reject(ex);
}
}
let extra = {
now: this.now(),
localtimeOffsetMsec: this.localtimeOffsetMsec,
};
let request = this.newHAWKAuthenticatedRESTRequest(uri, credentials, extra);
try {
if (method == "post" || method == "put" || method == "patch") {
request[method](payloadObj, onComplete);
} else {
request[method](onComplete);
}
} catch (ex) {
log.error("Failed to make hawk request", ex);
deferred.reject(ex);
}
return deferred.promise;
},
/*
* The prefix used for all notifications sent by this module. This
* allows the handler of notifications to be sure they are handling
* notifications for the service they expect.
*
* If not set, no notifications will be sent.
*/
observerPrefix: null,
// Given an optional header value, notify that a backoff has been requested.
_maybeNotifyBackoff: function (response, headerName) {
if (!this.observerPrefix || !response.headers) {
return;
}
let headerVal = response.headers[headerName];
if (!headerVal) {
return;
}
let backoffInterval;
try {
backoffInterval = parseInt(headerVal, 10);
} catch (ex) {
log.error("hawkclient response had invalid backoff value in '" +
headerName + "' header: " + headerVal);
return;
}
Observers.notify(this.observerPrefix + ":backoff:interval", backoffInterval);
},
// override points for testing.
newHAWKAuthenticatedRESTRequest: function(uri, credentials, extra) {
return new HAWKAuthenticatedRESTRequest(uri, credentials, extra);
},
}