gecko/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js

463 lines
15 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/. */
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;
// COMPLETE_LENGTH and PARTIAL_LENGTH copied from nsUrlClassifierDBService.h,
// they correspond to the length, in bytes, of a hash prefix and the total
// hash.
const COMPLETE_LENGTH = 32;
const PARTIAL_LENGTH = 4;
// These backoff related constants are taken from v2 of the Google Safe Browsing
// API.
// BACKOFF_ERRORS: the number of errors incurred until we start to back off.
// BACKOFF_INTERVAL: the initial time, in seconds, to wait once we start backing
// off.
// BACKOFF_MAX: as the backoff time doubles after each failure, this is a
// ceiling on the time to wait, in seconds.
// BACKOFF_TIME: length of the interval of time, in seconds, during which errors
// are taken into account.
const BACKOFF_ERRORS = 2;
const BACKOFF_INTERVAL = 30 * 60;
const BACKOFF_MAX = 8 * 60 * 60;
const BACKOFF_TIME = 5 * 60;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://gre/modules/Services.jsm");
function HashCompleter() {
// This is a HashCompleterRequest and is used by multiple calls to |complete|
// in succession to avoid unnecessarily creating requests. Once it has been
// started, this is set to null again.
this._currentRequest = null;
// Whether we have been informed of a shutdown by the xpcom-shutdown event.
this._shuttingDown = false;
// All of these backoff properties are different per completer as the DB
// service keeps one completer per table.
//
// _backoff tells us whether we are "backing off" from making requests.
// It is set in |noteServerResponse| and set after a number of failures.
this._backoff = false;
// _backoffTime tells us how long we should wait (in seconds) before making
// another request.
this._backoffTime = 0;
// _nextRequestTime is the earliest time at which we are allowed to make
// another request by the backoff policy. It is measured in milliseconds.
this._nextRequestTime = 0;
// A list of the times at which a failed request was made, recorded in
// |noteServerResponse|. Sorted by oldest to newest and its length is clamped
// by BACKOFF_ERRORS.
this._errorTimes = [];
Services.obs.addObserver(this, "xpcom-shutdown", true);
}
HashCompleter.prototype = {
classID: Components.ID("{9111de73-9322-4bfc-8b65-2b727f3e6ec8}"),
QueryInterface: XPCOMUtils.generateQI([Ci.nsIUrlClassifierHashCompleter,
Ci.nsIRunnable,
Ci.nsIObserver,
Ci.nsISupportsWeakReference,
Ci.nsISupports]),
// This is mainly how the HashCompleter interacts with other components.
// Even though it only takes one partial hash and callback, subsequent
// calls are made into the same HTTP request by using a thread dispatch.
complete: function HC_complete(aPartialHash, aCallback) {
if (!this._currentRequest) {
this._currentRequest = new HashCompleterRequest(this);
// It's possible for getHashUrl to not be set, usually at start-up.
if (this._getHashUrl) {
Services.tm.currentThread.dispatch(this, Ci.nsIThread.DISPATCH_NORMAL);
}
}
this._currentRequest.add(aPartialHash, aCallback);
},
// This is called when either the getHashUrl has been set or after a few calls
// to |complete|. It starts off the HTTP request by making a |begin| call
// to the HashCompleterRequest.
run: function HC_run() {
if (this._shuttingDown) {
this._currentRequest = null;
throw Cr.NS_ERROR_NOT_INITIALIZED;
}
if (!this._currentRequest) {
return;
}
if (!this._getHashUrl) {
throw Cr.NS_ERROR_NOT_INITIALIZED;
}
let url = this._getHashUrl;
let uri = Services.io.newURI(url, null, null);
this._currentRequest.setURI(uri);
// If |begin| fails, we should get rid of our request.
try {
this._currentRequest.begin();
}
finally {
this._currentRequest = null;
}
},
get gethashUrl() {
return this._getHashUrl;
},
// Because we hold off on making a request until we have a valid getHashUrl,
// we kick off the process here.
set gethashUrl(aNewUrl) {
this._getHashUrl = aNewUrl;
if (this._currentRequest) {
Services.tm.currentThread.dispatch(this, Ci.nsIThread.DISPATCH_NORMAL);
}
},
// This handles all the logic about setting a back off time based on
// server responses. It should only be called once in the life time of a
// request.
// The logic behind backoffs is documented in the Google Safe Browsing API,
// the general idea is that a completer should go into backoff mode after
// BACKOFF_ERRORS errors in the last BACKOFF_TIME seconds. From there,
// we do not make a request for BACKOFF_INTERVAL seconds and for every failed
// request after that we double how long to wait, to a maximum of BACKOFF_MAX.
// Note that even in the case of a successful response we still keep a history
// of past errors.
noteServerResponse: function HC_noteServerResponse(aSuccess) {
if (aSuccess) {
this._backoff = false;
this._nextRequestTime = 0;
this._backoffTime = 0;
return;
}
let now = Date.now();
// We only alter the size of |_errorTimes| here, so we can guarantee that
// its length is at most BACKOFF_ERRORS.
this._errorTimes.push(now);
if (this._errorTimes.length > BACKOFF_ERRORS) {
this._errorTimes.shift();
}
if (this._backoff) {
this._backoffTime *= 2;
} else if (this._errorTimes.length == BACKOFF_ERRORS &&
((now - this._errorTimes[0]) / 1000) <= BACKOFF_TIME) {
this._backoff = true;
this._backoffTime = BACKOFF_INTERVAL;
}
if (this._backoff) {
this._backoffTime = Math.min(this._backoffTime, BACKOFF_MAX);
this._nextRequestTime = now + (this._backoffTime * 1000);
}
},
// This is not included on the interface but is used to communicate to the
// HashCompleterRequest. It returns a time in milliseconds.
get nextRequestTime() {
return this._nextRequestTime;
},
observe: function HC_observe(aSubject, aTopic, aData) {
if (aTopic == "xpcom-shutdown") {
this._shuttingDown = true;
}
},
};
function HashCompleterRequest(aCompleter) {
// HashCompleter object that created this HashCompleterRequest.
this._completer = aCompleter;
// The internal set of hashes and callbacks that this request corresponds to.
this._requests = [];
// URI to query for hash completions. Largely comes from the
// browser.safebrowsing.gethashURL pref.
this._uri = null;
// nsIChannel that the hash completion query is transmitted over.
this._channel = null;
// Response body of hash completion. Created in onDataAvailable.
this._response = "";
// Whether we have been informed of a shutdown by the xpcom-shutdown event.
this._shuttingDown = false;
}
HashCompleterRequest.prototype = {
QueryInterface: XPCOMUtils.generateQI([Ci.nsIRequestObserver,
Ci.nsIStreamListener,
Ci.nsIObserver,
Ci.nsISupports]),
// This is called by the HashCompleter to add a hash and callback to the
// HashCompleterRequest. It must be called before calling |begin|.
add: function HCR_add(aPartialHash, aCallback) {
this._requests.push({
partialHash: aPartialHash,
callback: aCallback,
responses: [],
});
},
// This initiates the HTTP request. It can fail due to backoff timings and
// will notify all callbacks as necessary.
begin: function HCR_begin() {
if (Date.now() < this._completer.nextRequestTime) {
this.notifyFailure(Cr.NS_ERROR_ABORT);
return;
}
Services.obs.addObserver(this, "xpcom-shutdown", false);
try {
this.openChannel();
}
catch (err) {
this.notifyFailure(err);
throw err;
}
},
setURI: function HCR_setURI(aURI) {
this._uri = aURI;
},
// Creates an nsIChannel for the request and fills the body.
openChannel: function HCR_openChannel() {
let loadFlags = Ci.nsIChannel.INHIBIT_CACHING |
Ci.nsIChannel.LOAD_BYPASS_CACHE;
let channel = Services.io.newChannelFromURI(this._uri);
channel.loadFlags = loadFlags;
this._channel = channel;
let body = this.buildRequest();
this.addRequestBody(body);
channel.asyncOpen(this, null);
},
// Returns a string for the request body based on the contents of
// this._requests.
buildRequest: function HCR_buildRequest() {
// Sometimes duplicate entries are sent to HashCompleter but we do not need
// to propagate these to the server. (bug 633644)
let prefixes = [];
for (let i = 0; i < this._requests.length; i++) {
let request = this._requests[i];
if (prefixes.indexOf(request.partialHash) == -1) {
prefixes.push(request.partialHash);
}
}
// Randomize the order to obscure the original request from noise
// unbiased Fisher-Yates shuffle
let i = prefixes.length;
while (i--) {
let j = Math.floor(Math.random() * (i + 1));
let temp = prefixes[i];
prefixes[i] = prefixes[j];
prefixes[j] = temp;
}
let body;
body = PARTIAL_LENGTH + ":" + (PARTIAL_LENGTH * prefixes.length) +
"\n" + prefixes.join("");
return body;
},
// Sets the request body of this._channel.
addRequestBody: function HCR_addRequestBody(aBody) {
let inputStream = Cc["@mozilla.org/io/string-input-stream;1"].
createInstance(Ci.nsIStringInputStream);
inputStream.setData(aBody, aBody.length);
let uploadChannel = this._channel.QueryInterface(Ci.nsIUploadChannel);
uploadChannel.setUploadStream(inputStream, "text/plain", -1);
let httpChannel = this._channel.QueryInterface(Ci.nsIHttpChannel);
httpChannel.requestMethod = "POST";
},
// Parses the response body and eventually adds items to the |responses| array
// for elements of |this._requests|.
handleResponse: function HCR_handleResponse() {
if (this._response == "") {
return;
}
let start = 0;
let length = this._response.length;
while (start != length)
start = this.handleTable(start);
},
// This parses a table entry in the response body and calls |handleItem|
// for complete hash in the table entry.
handleTable: function HCR_handleTable(aStart) {
let body = this._response.substring(aStart);
// deal with new line indexes as there could be
// new line characters in the data parts.
let newlineIndex = body.indexOf("\n");
if (newlineIndex == -1) {
throw errorWithStack();
}
let header = body.substring(0, newlineIndex);
let entries = header.split(":");
if (entries.length != 3) {
throw errorWithStack();
}
let list = entries[0];
let addChunk = parseInt(entries[1]);
let dataLength = parseInt(entries[2]);
if (dataLength % COMPLETE_LENGTH != 0 ||
dataLength == 0 ||
dataLength > body.length - (newlineIndex + 1)) {
throw errorWithStack();
}
let data = body.substr(newlineIndex + 1, dataLength);
for (let i = 0; i < (dataLength / COMPLETE_LENGTH); i++) {
this.handleItem(data.substr(i * COMPLETE_LENGTH, COMPLETE_LENGTH), list,
addChunk);
}
return aStart + newlineIndex + 1 + dataLength;
},
// This adds a complete hash to any entry in |this._requests| that matches
// the hash.
handleItem: function HCR_handleItem(aData, aTableName, aChunkId) {
for (let i = 0; i < this._requests.length; i++) {
let request = this._requests[i];
if (aData.substring(0,4) == request.partialHash) {
request.responses.push({
completeHash: aData,
tableName: aTableName,
chunkId: aChunkId,
});
}
}
},
// notifySuccess and notifyFailure are used to alert the callbacks with
// results. notifySuccess makes |completion| and |completionFinished| calls
// while notifyFailure only makes a |completionFinished| call with the error
// code.
notifySuccess: function HCR_notifySuccess() {
for (let i = 0; i < this._requests.length; i++) {
let request = this._requests[i];
for (let j = 0; j < request.responses.length; j++) {
let response = request.responses[j];
request.callback.completion(response.completeHash, response.tableName,
response.chunkId);
}
request.callback.completionFinished(Cr.NS_OK);
}
},
notifyFailure: function HCR_notifyFailure(aStatus) {
for (let i = 0; i < this._requests; i++) {
let request = this._requests[i];
request.callback.completionFinished(aStatus);
}
},
onDataAvailable: function HCR_onDataAvailable(aRequest, aContext,
aInputStream, aOffset, aCount) {
let sis = Cc["@mozilla.org/scriptableinputstream;1"].
createInstance(Ci.nsIScriptableInputStream);
sis.init(aInputStream);
this._response += sis.readBytes(aCount);
},
onStartRequest: function HCR_onStartRequest(aRequest, aContext) {
// At this point no data is available for us and we have no reason to
// terminate the connection, so we do nothing until |onStopRequest|.
},
onStopRequest: function HCR_onStopRequest(aRequest, aContext, aStatusCode) {
Services.obs.removeObserver(this, "xpcom-shutdown");
if (this._shuttingDown) {
throw Cr.NS_ERROR_ABORT;
}
if (Components.isSuccessCode(aStatusCode)) {
let channel = aRequest.QueryInterface(Ci.nsIHttpChannel);
let success = channel.requestSucceeded;
if (!success) {
aStatusCode = Cr.NS_ERROR_ABORT;
}
}
let success = Components.isSuccessCode(aStatusCode);
this._completer.noteServerResponse(success);
if (success) {
try {
this.handleResponse();
}
catch (err) {
dump(err.stack);
aStatusCode = err.value;
success = false;
}
}
if (success) {
this.notifySuccess();
} else {
this.notifyFailure(aStatusCode);
}
},
observe: function HCR_observe(aSubject, aTopic, aData) {
if (aTopic != "xpcom-shutdown") {
return;
}
this._shuttingDown = true;
if (this._channel) {
this._channel.cancel(Cr.NS_ERROR_ABORT);
}
},
};
// Converts a URL safe base64 string to a normal base64 string. Will not change
// normal base64 strings. This is modelled after the same function in
// nsUrlClassifierUtils.h.
function unUrlsafeBase64(aStr) {
return !aStr ? "" : aStr.replace(/-/g, "+")
.replace(/_/g, "/");
}
function errorWithStack() {
let err = new Error();
err.value = Cr.NS_ERROR_FAILURE;
return err;
}
this.NSGetFactory = XPCOMUtils.generateNSGetFactory([HashCompleter]);