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Add trusted-replace-fetch-response scriptlet
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This scriplet requires a trusted source.

Related issue:
uBlockOrigin/uBlock-issues#2742

See AdGuard's documentation for usage:
https://github.com/AdguardTeam/Scriptlets/blob/master/wiki/about-trusted-scriptlets.md#trusted-replace-fetch-response
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@gorhill
gorhill committed Aug 5, 2023
1 parent 9f91335 commit 82a7d11
Showing 1 changed file with 120 additions and 32 deletions.
152 changes: 120 additions & 32 deletions assets/resources/scriptlets.js
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Expand Up @@ -53,6 +53,9 @@ function safeSelf() {
'RegExp_exec': self.RegExp.prototype.exec,
'addEventListener': self.EventTarget.prototype.addEventListener,
'removeEventListener': self.EventTarget.prototype.removeEventListener,
'fetch': self.fetch,
'jsonParse': self.JSON.parse.bind(self.JSON),
'jsonStringify': self.JSON.stringify.bind(self.JSON),
'log': console.log.bind(console),
'uboLog': function(...args) {
if ( args.length === 0 ) { return; }
Expand Down Expand Up @@ -103,10 +106,15 @@ builtinScriptlets.push({
function patternToRegex(pattern, flags = undefined) {
if ( pattern === '' ) { return /^/; }
const match = /^\/(.+)\/([gimsu]*)$/.exec(pattern);
if ( match !== null ) {
if ( match === null ) {
return new RegExp(pattern.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'), flags);
}
try {
return new RegExp(match[1], match[2] || flags);
}
return new RegExp(pattern.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'), flags);
catch(ex) {
}
return /^/;
}

/******************************************************************************/
Expand Down Expand Up @@ -210,11 +218,14 @@ function runAtHtmlElement(fn) {
/******************************************************************************/

builtinScriptlets.push({
name: 'get-extra-args-entries.fn',
fn: getExtraArgsEntries,
name: 'get-extra-args.fn',
fn: getExtraArgs,
dependencies: [
'get-extra-args-entries.fn',
],
});
function getExtraArgsEntries(args, offset) {
return args.slice(offset).reduce((out, v, i, a) => {
function getExtraArgs(args, offset = 0) {
const entries = args.slice(offset).reduce((out, v, i, a) => {
if ( (i & 1) === 0 ) {
const rawValue = a[i+1];
const value = /^\d+$/.test(rawValue)
Expand All @@ -224,28 +235,7 @@ function getExtraArgsEntries(args, offset) {
}
return out;
}, []);
}

builtinScriptlets.push({
name: 'get-extra-args-map.fn',
fn: getExtraArgsMap,
dependencies: [
'get-extra-args-entries.fn',
],
});
function getExtraArgsMap(args, offset = 0) {
return new Map(getExtraArgsEntries(args, offset));
}

builtinScriptlets.push({
name: 'get-extra-args.fn',
fn: getExtraArgs,
dependencies: [
'get-extra-args-entries.fn',
],
});
function getExtraArgs(args, offset = 0) {
return Object.fromEntries(getExtraArgsEntries(args, offset));
return Object.fromEntries(entries);
}

/******************************************************************************/
Expand Down Expand Up @@ -447,7 +437,7 @@ function setConstantCore(
if ( Math.abs(cValue) > 0x7FFF ) { return; }
} else if ( trusted ) {
if ( cValue.startsWith('{') && cValue.endsWith('}') ) {
try { cValue = JSON.parse(cValue).value; } catch(ex) { return; }
try { cValue = safe.jsonParse(cValue).value; } catch(ex) { return; }
}
} else {
return;
Expand Down Expand Up @@ -2415,7 +2405,7 @@ function xmlPrune(
log(`xmlPrune: ${item.constructor.name}.${item.nodeName} removed`);
}
} catch(ex) {
if ( log ) { safeSelf().uboLog(ex); }
log(ex);
}
return xmlDoc;
};
Expand All @@ -2438,13 +2428,12 @@ function xmlPrune(
if ( arg instanceof Request ) { return arg.url; }
return String(arg);
};
const realFetch = self.fetch;
self.fetch = new Proxy(self.fetch, {
apply: function(target, thisArg, args) {
if ( reUrl.test(urlFromArg(args[0])) === false ) {
return Reflect.apply(target, thisArg, args);
}
return realFetch(...args).then(realResponse =>
return safe.fetch(...args).then(realResponse =>
realResponse.text().then(text =>
new Response(pruneFromText(text), {
status: realResponse.status,
Expand Down Expand Up @@ -3329,4 +3318,103 @@ function trustedSetLocalStorageItem(key = '', value = '') {
setLocalStorageItemCore('local', true, key, value);
}

/*******************************************************************************
*
* trusted-replace-fetch-response.js
*
* Replaces response text content of fetch requests if all given parameters
* match.
*
* Reference:
* https://github.com/AdguardTeam/Scriptlets/blob/master/src/scriptlets/trusted-replace-fetch-response.js
*
**/

builtinScriptlets.push({
name: 'trusted-replace-fetch-response.js',
requiresTrust: true,
fn: trustedReplaceFetchResponse,
dependencies: [
'get-extra-args.fn',
'pattern-to-regex.fn',
'safe-self.fn',
'should-log.fn',
],
});
function trustedReplaceFetchResponse(
pattern = '',
replacement = '',
propsToMatch = ''
) {
const safe = safeSelf();
const extraArgs = getExtraArgs(Array.from(arguments), 3);
const logLevel = shouldLog({
log: pattern === '' || extraArgs.log,
});
const log = logLevel ? ((...args) => { safe.uboLog(...args); }) : (( ) => { });
if ( pattern === '*' ) { pattern = '.*'; }
const rePattern = patternToRegex(pattern);
const propNeedles = new Map();
for ( const needle of propsToMatch.split(/\s+/) ) {
const [ prop, value ] = needle.split(':');
if ( prop === '' ) { continue; }
propNeedles.set(prop, patternToRegex(value));
}
self.fetch = new Proxy(self.fetch, {
apply: function(target, thisArg, args) {
if ( logLevel === true ) {
log('trusted-replace-fetch-response:', JSON.stringify(Array.from(args)).slice(1,-1));
}
const fetchPromise = Reflect.apply(target, thisArg, args);
if ( pattern === '' ) { return fetchPromise; }
let skip = false;
if ( propNeedles.size !== 0 ) {
const fetchDetails = {};
if ( args[0] instanceof self.Request ) {
Object.assign(fetchDetails, args[0]);
} else {
Object.assign(fetchDetails, { url: args[0] });
}
if ( args[1] instanceof Object ) {
Object.assign(fetchDetails, args[1]);
}
for ( const prop of Object.keys(fetchDetails) ) {
let value = fetchDetails[prop];
if ( typeof value !== 'string' ) {
try { value = JSON.stringify(value); }
catch(ex) { }
}
if ( typeof value !== 'string' ) { continue; }
const needle = propNeedles.get(prop);
if ( needle === undefined ) { continue; }
if ( needle.test(value) ) { continue; }
skip = true;
break;
}
}
if ( skip ) { return fetchPromise; }
return fetchPromise.then(responseBefore => {
return responseBefore.text().then(textBefore => {
const textAfter = textBefore.replace(rePattern, replacement);
const responseAfter = new Response(textAfter, {
status: responseBefore.status,
statusText: responseBefore.statusText,
headers: responseBefore.headers,
});
Object.defineProperties(responseAfter, {
ok: { value: responseBefore.ok },
redirected: { value: responseBefore.redirected },
type: { value: responseBefore.type },
url: { value: responseBefore.url },
});
return responseAfter;
}).catch(reason => {
log('trusted-replace-fetch-response:', reason);
return responseBefore;
});
});
}
});
}

/******************************************************************************/

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