mirror of
https://github.com/gorhill/uBlock.git
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131 lines
4.1 KiB
JavaScript
131 lines
4.1 KiB
JavaScript
/*******************************************************************************
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µBlock - a Chromium browser extension to block requests.
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Copyright (C) 2014 Raymond Hill
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see {http://www.gnu.org/licenses/}.
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Home: https://github.com/gorhill/uBlock
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*/
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// This is the reference client-side implementation of µBlock's messaging
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// infrastructure. The "server"-side implementation is in messaging.js.
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// The client-side implementation creates a port in order to connect to
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// µBlock's background page. With this port we can "ask", "tell" or "announce":
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//
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// "ask": send a request and expect an answer using a callback.
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// "tell": send a request with no expectation of an answer.
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// "announce": send a request to be relayed to all connections -- no answer
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// expected.
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//
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// The tricky part in this implementation is to ensure all the requests are
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// uniquely identified, so that the background-page can keep track of these
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// until it is ready to send back an answer, which will be tagged with the
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// same id. The uniqueness must be true for all ports which connect to the
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// background page at any given time.
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//
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// Currently using Math.random() to generate this id... I don't know about the
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// implementation of Math.random(), but as long as I have a good expectation
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// of uniqueness, it's ok, we are not dealing with critical stuff here.
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var messaging = (function(name){
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var port = null;
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var dangling = false;
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var requestId = 1;
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var requestIdToCallbackMap = {};
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var listenCallback = null;
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var onPortMessage = function(details) {
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if ( typeof details.id !== 'number' ) {
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return;
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}
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// Announcement?
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if ( details.id < 0 ) {
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if ( listenCallback ) {
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listenCallback(details.msg);
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}
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return;
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}
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var callback = requestIdToCallbackMap[details.id];
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if ( !callback ) {
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return;
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}
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callback(details.msg);
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delete requestIdToCallbackMap[details.id];
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checkDisconnect();
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};
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var start = function(name) {
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port = chrome.runtime.connect({
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name: name +
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'/' +
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String.fromCharCode(
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Math.random() * 0x7FFF | 0,
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Math.random() * 0x7FFF | 0,
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Math.random() * 0x7FFF | 0,
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Math.random() * 0x7FFF | 0
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)
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});
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port.onMessage.addListener(onPortMessage);
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};
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if ( typeof name === 'string' && name.length > 0 ) {
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start(name);
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}
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var stop = function() {
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listenCallback = null;
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dangling = true;
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checkDisconnect();
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};
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var ask = function(msg, callback) {
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if ( !callback ) {
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tell(msg);
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return;
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}
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var id = requestId++;
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port.postMessage({ id: id, msg: msg });
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requestIdToCallbackMap[id] = callback;
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};
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var tell = function(msg) {
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port.postMessage({ id: 0, msg: msg });
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};
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var listen = function(callback) {
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listenCallback = callback;
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};
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var checkDisconnect = function() {
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if ( !dangling ) {
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return;
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}
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if ( Object.keys(requestIdToCallbackMap).length ) {
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return;
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}
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port.disconnect();
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port = null;
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};
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return {
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start: start,
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stop: stop,
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ask: ask,
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tell: tell,
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listen: listen
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};
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})();
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