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fix(adblocker): inject scriplets with browser.contentScripts on Firefox #2074

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124 changes: 118 additions & 6 deletions src/background/adblocker.js
Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,12 @@ export async function reloadMainEngine() {
await engines.create(engines.MAIN_ENGINE);
console.info('[adblocker] Main engine reloaded with no filters');
}
if (
__PLATFORM__ === 'firefox' &&
ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION
) {
contentScripts.unregisterAll();
}
}

let updating = false;
Expand Down Expand Up @@ -163,7 +169,68 @@ export const setup = asyncSetup('adblocker', [
),
]);

function injectScriptlets(filters, tabId, frameId) {
let ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION = false;
if (__PLATFORM__ === 'firefox') {
OptionsObserver.addListener('experimentalFilters', (value) => {
ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION = value;
if (!value) {
contentScripts.unregisterAll();
}
});

OptionsObserver.addListener('paused', async (paused) => {
if (!ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION) return;
for (const hostname of Object.keys(paused)) {
contentScripts.unregister(hostname);
}
});
}

const contentScripts = (() => {
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const map = new Map();
return {
async register(hostname, code) {
this.unregister(hostname);
try {
const contentScript = await browser.contentScripts.register({
js: [
{
code,
},
],
allFrames: true,
matches: [`https://*.${hostname}/*`, `http://*.${hostname}/*`],
matchAboutBlank: true,
matchOriginAsFallback: true,
runAt: 'document_start',
world: 'MAIN',
});
map.set(hostname, contentScript);
} catch (e) {
console.warn(e);
this.unregister(hostname);
}
},
isRegistered(hostname) {
return map.has(hostname);
},
unregister(hostname) {
const contentScript = map.get(hostname);
if (contentScript) {
contentScript.unregister();
map.delete(hostname);
}
},
unregisterAll() {
for (const hostname of map.keys()) {
this.unregister(hostname);
}
},
};
})();

function injectScriptlets(filters, tabId, frameId, hostname) {
let contentScript = '';
for (const filter of filters) {
const parsed = filter.parseScript();

Expand All @@ -177,12 +244,22 @@ function injectScriptlets(filters, tabId, frameId) {

const scriptletName = `${parsed.name}${parsed.name.endsWith('.js') ? '' : '.js'}`;
const scriptlet = scriptlets[scriptletName];
const func = scriptlet.func;
const args = parsed.args.map((arg) => decodeURIComponent(arg));

if (!scriptlet) {
console.warn('[adblocker] unknown scriptlet with name:', scriptletName);
continue;
}

if (
__PLATFORM__ === 'firefox' &&
ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION
) {
contentScript += `(${func.toString()})(...${JSON.stringify(args)});\n`;
continue;
}

chrome.scripting.executeScript(
{
injectImmediately: true,
Expand All @@ -193,8 +270,8 @@ function injectScriptlets(filters, tabId, frameId) {
tabId,
frameIds: [frameId],
},
func: scriptlet.func,
args: parsed.args.map((arg) => decodeURIComponent(arg)),
func,
args,
},
() => {
if (chrome.runtime.lastError) {
Expand All @@ -203,6 +280,19 @@ function injectScriptlets(filters, tabId, frameId) {
},
);
}

if (
__PLATFORM__ === 'firefox' &&
ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION
) {
if (filters.length === 0) {
contentScripts.unregister(hostname);
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I'm wondering if this part of the code is necessary or how it should be best handled.
When the engine updates, it should automatically clear the content scripts (contentScripts.unregisterAll). There might be potential for race conditions, but in principle, it should eventually take care of unregistering.

Is the code here intended especially for pause (which won't trigger an engine reload)? If so, would be good to leave a comment explaining this.

} else if (!contentScripts.isRegistered(hostname)) {
contentScripts.register(hostname, contentScript);
} else {
// do nothing if already registered
}
}
}

function injectStyles(styles, tabId, frameId) {
Expand All @@ -224,6 +314,8 @@ function injectStyles(styles, tabId, frameId) {
}

async function injectCosmetics(details, config) {
const { bootstrap: isBootstrap, scriptletsOnly } = config;

try {
setup.pending && (await setup.pending);
} catch (e) {
Expand All @@ -237,6 +329,14 @@ async function injectCosmetics(details, config) {
const domain = parsed.domain || '';
const hostname = parsed.hostname || '';

if (
__PLATFORM__ === 'firefox' &&
ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION &&
scriptletsOnly &&
contentScripts.isRegistered(hostname)
)
return;

if (isPaused(options, hostname)) return;

const tabHostname = tabStats.get(tabId)?.hostname;
Expand All @@ -245,7 +345,6 @@ async function injectCosmetics(details, config) {
}

const engine = engines.get(engines.MAIN_ENGINE);
const isBootstrap = config.bootstrap;

{
const { matches } = engine.matchCosmeticFilters({
Expand Down Expand Up @@ -282,8 +381,12 @@ async function injectCosmetics(details, config) {
}
}

if (isBootstrap && scriptFilters.length > 0) {
injectScriptlets(scriptFilters, tabId, frameId);
if (isBootstrap) {
injectScriptlets(scriptFilters, tabId, frameId, hostname);
}

if (scriptletsOnly) {
return;
}

const { styles } = engine.injectCosmeticFilters(styleFilters, {
Expand Down Expand Up @@ -377,6 +480,15 @@ function isTrusted(request, type) {
}

if (__PLATFORM__ === 'firefox') {
chrome.webNavigation.onBeforeNavigate.addListener(
(details) => {
if (ENABLE_FIREFOX_CONTENT_SCRIPT_SCRIPLET_INJECTION) {
injectCosmetics(details, { bootstrap: true, scriptletsOnly: true });
}
},
{ url: [{ urlPrefix: 'http://' }, { urlPrefix: 'https://' }] },
);

function isExtensionRequest(details) {
return (
(details.tabId === -1 && details.url.startsWith('moz-extension://')) ||
Expand Down
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