1 files changed, 199 insertions, 0 deletions
diff --git a/data/extensions/uBlock0@raymondhill.net/js/httpheader-filtering.js b/data/extensions/uBlock0@raymondhill.net/js/httpheader-filtering.js
new file mode 100644
index 0000000..c5aa918
--- /dev/null
+++ b/data/extensions/uBlock0@raymondhill.net/js/httpheader-filtering.js
@@ -0,0 +1,199 @@
+/*******************************************************************************
+
+    uBlock Origin - a comprehensive, efficient content blocker
+    Copyright (C) 2021-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+import { StaticExtFilteringHostnameDB } from './static-ext-filtering-db.js';
+import { entityFromHostname } from './uri-utils.js';
+import logger from './logger.js';
+import { sessionFirewall } from './filtering-engines.js';
+import µb from './background.js';
+
+/******************************************************************************/
+
+const duplicates = new Set();
+const filterDB = new StaticExtFilteringHostnameDB();
+
+let acceptedCount = 0;
+let discardedCount = 0;
+
+const headerIndexFromName = function(name, headers, start = 0) {
+    for ( let i = start; i < headers.length; i++ ) {
+        if ( headers[i].name.toLowerCase() !== name ) { continue; }
+        return i;
+    }
+    return -1;
+};
+
+const logOne = function(isException, token, fctxt) {
+    fctxt.duplicate()
+        .setRealm('extended')
+        .setType('header')
+        .setFilter({
+            modifier: true,
+            result: isException ? 2 : 1,
+            source: 'extended',
+            raw: `${(isException ? '#@#' : '##')}^responseheader(${token})`,
+        })
+        .toLogger();
+};
+
+const httpheaderFilteringEngine = {
+    get acceptedCount() {
+        return acceptedCount;
+    },
+    get discardedCount() {
+        return discardedCount;
+    }
+};
+
+httpheaderFilteringEngine.reset = function() {
+    filterDB.clear();
+    duplicates.clear();
+    acceptedCount = 0;
+    discardedCount = 0;
+};
+
+httpheaderFilteringEngine.freeze = function() {
+    duplicates.clear();
+    filterDB.collectGarbage();
+};
+
+httpheaderFilteringEngine.compile = function(parser, writer) {
+    writer.select('HTTPHEADER_FILTERS');
+
+    const isException = parser.isException();
+    const headerName = parser.getResponseheaderName();
+
+    // Tokenless is meaningful only for exception filters.
+    if ( headerName === '' && isException === false ) { return; }
+
+    // Only exception filters are allowed to be global.
+    if ( parser.hasOptions() === false ) {
+        if ( isException ) {
+            writer.push([ 64, '', 1, headerName ]);
+        }
+        return;
+    }
+
+    // https://github.com/gorhill/uBlock/issues/3375
+    //   Ignore instances of exception filter with negated hostnames,
+    //   because there is no way to create an exception to an exception.
+
+    for ( const { hn, not, bad } of parser.getExtFilterDomainIterator() ) {
+        if ( bad ) { continue; }
+        const prefix = ((isException ? 1 : 0) ^ (not ? 1 : 0)) ? '-' : '+';
+        writer.push([ 64, hn, `${prefix}${headerName}` ]);
+    }
+};
+
+// 01234567890123456789
+// responseheader(name)
+//                ^   ^
+//               15  -1
+
+httpheaderFilteringEngine.fromCompiledContent = function(reader) {
+    reader.select('HTTPHEADER_FILTERS');
+
+    while ( reader.next() ) {
+        acceptedCount += 1;
+        const fingerprint = reader.fingerprint();
+        if ( duplicates.has(fingerprint) ) {
+            discardedCount += 1;
+            continue;
+        }
+        duplicates.add(fingerprint);
+        const args = reader.args();
+        filterDB.store(args[1], args[2]);
+    }
+};
+
+httpheaderFilteringEngine.apply = function(fctxt, headers) {
+    if ( filterDB.size === 0 ) { return; }
+
+    const hostname = fctxt.getHostname();
+    if ( hostname === '' ) { return; }
+
+    const all = new Set();
+    filterDB.retrieveSpecifics(all, hostname);
+    const entity = entityFromHostname(hostname, fctxt.getDomain());
+    filterDB.retrieveSpecifics(all, entity);
+    filterDB.retrieveSpecificsByRegex(all, hostname, fctxt.url);
+    filterDB.retrieveGenerics(all);
+    if ( all.size === 0 ) { return; }
+
+    // https://github.com/gorhill/uBlock/issues/2835
+    //   Do not filter response headers if the site is under an `allow` rule.
+    if ( µb.userSettings.advancedUserEnabled ) {
+        if ( sessionFirewall.evaluateCellZY(hostname, hostname, '*') === 2 ) { return; }
+    }
+
+    // Split filters in different groups
+    const filters = new Set();
+    const exceptions = new Set();
+    for ( const s of all ) {
+        const selector = s.slice(1);
+        if ( s.charCodeAt(0) === 0x2D /* - */ ) {
+            exceptions.add(selector);
+        } else {
+            filters.add(selector);
+        }
+    }
+
+    const hasGlobalException = exceptions.has('');
+
+    let modified = false;
+    let i = 0;
+
+    for ( const name of filters ) {
+        const isExcepted = hasGlobalException || exceptions.has(name);
+        if ( isExcepted ) {
+            if ( logger.enabled ) {
+                logOne(true, hasGlobalException ? '' : name, fctxt);
+            }
+            continue;
+        }
+        i = 0;
+        for (;;) {
+            i = headerIndexFromName(name, headers, i);
+            if ( i === -1 ) { break; }
+            headers.splice(i, 1);
+            if ( logger.enabled ) {
+                logOne(false, name, fctxt);
+            }
+            modified = true;
+        }
+    }
+
+    return modified;
+};
+
+httpheaderFilteringEngine.toSelfie = function() {
+    return filterDB.toSelfie();
+};
+
+httpheaderFilteringEngine.fromSelfie = function(selfie) {
+    filterDB.fromSelfie(selfie);
+};
+
+/******************************************************************************/
+
+export default httpheaderFilteringEngine;
+
+/******************************************************************************/