Blocking large media elements also prevents autoplay, regardless of size

gorhill · gorhill · commit 73ce4e6bcf55 · 2024-10-02T13:39:36.000-04:00
Related issue: uBlockOrigin/uBlock-issues#3394 When the "No large media elements" per-site switch is toggled on, it will also act to prevent autoplay of video/audio media, regardless of their size. This also works for xhr-based media streaming. If blocking by size is not desirable while blocking autoplay is desired, one can toggle on "No large media elements" switch while setting "Block media elements larger than ..." to a very high value.
diff --git a/platform/chromium/vapi-background-ext.js b/platform/chromium/vapi-background-ext.js
@@ -19,10 +19,6 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-/* globals browser */
-
-'use strict';
-
 /******************************************************************************/
 
 // https://github.com/uBlockOrigin/uBlock-issues/issues/1659
@@ -90,71 +86,47 @@ vAPI.Tabs = class extends vAPI.Tabs {
         ['gif','image'],['ico','image'],['jpeg','image'],['jpg','image'],['png','image'],['webp','image']
     ]);
 
-    const headerValue = (headers, name) => {
-        let i = headers.length;
-        while ( i-- ) {
-            if ( headers[i].name.toLowerCase() === name ) {
-                return headers[i].value.trim();
-            }
-        }
-        return '';
-    };
-
     const parsedURL = new URL('https://www.example.org/');
 
-    // Extend base class to normalize as per platform.
+    // Extend base class to normalize as per platform
 
     vAPI.Net = class extends vAPI.Net {
         normalizeDetails(details) {
             // Chromium 63+ supports the `initiator` property, which contains
-            // the URL of the origin from which the network request was made.
-            if (
-                typeof details.initiator === 'string' &&
-                details.initiator !== 'null'
-            ) {
+            // the URL of the origin from which the network request was made
+            if ( details.initiator && details.initiator !== 'null' ) {
                 details.documentUrl = details.initiator;
             }
-
-            let type = details.type;
-
+            const type = details.type;
             if ( type === 'imageset' ) {
                 details.type = 'image';
                 return;
             }
-
-            // The rest of the function code is to normalize type
             if ( type !== 'other' ) { return; }
-
-            // Try to map known "extension" part of URL to request type.
-            parsedURL.href = details.url;
-            const path = parsedURL.pathname,
-                  pos = path.indexOf('.', path.length - 6);
-            if ( pos !== -1 && (type = extToTypeMap.get(path.slice(pos + 1))) ) {
-                details.type = type;
+            // Try to map known "extension" part of URL to request type
+            if ( details.responseHeaders === undefined ) {
+                parsedURL.href = details.url;
+                const path = parsedURL.pathname;
+                const pos = path.indexOf('.', path.length - 6);
+                if ( pos !== -1 ) {
+                    details.type = extToTypeMap.get(path.slice(pos + 1)) || type;
+                }
                 return;
             }
-
-            // Try to extract type from response headers if present.
-            if ( details.responseHeaders ) {
-                type = headerValue(details.responseHeaders, 'content-type');
-                if ( type.startsWith('font/') ) {
-                    details.type = 'font';
-                    return;
-                }
-                if ( type.startsWith('image/') ) {
-                    details.type = 'image';
-                    return;
-                }
-                if ( type.startsWith('audio/') || type.startsWith('video/') ) {
-                    details.type = 'media';
-                    return;
-                }
+            // Try to extract type from response headers
+            const ctype = this.headerValue(details.responseHeaders, 'content-type');
+            if ( ctype.startsWith('font/') ) {
+                details.type = 'font';
+            } else if ( ctype.startsWith('image/') ) {
+                details.type = 'image';
+            } else if ( ctype.startsWith('audio/') || ctype.startsWith('video/') ) {
+                details.type = 'media';
             }
         }
 
         // https://www.reddit.com/r/uBlockOrigin/comments/9vcrk3/
         //   Some types can be mapped from 'other', thus include 'other' if and
-        //   only if the caller is interested in at least one of those types.
+        //   only if the caller is interested in at least one of those types
         denormalizeTypes(types) {
             if ( types.length === 0 ) {
                 return Array.from(this.validTypes);
diff --git a/platform/common/vapi-background.js b/platform/common/vapi-background.js
@@ -1382,6 +1382,14 @@ vAPI.Net = class {
         if ( this.suspendDepth !== 0 ) { return; }
         this.unsuspendAllRequests(discard);
     }
+    headerValue(headers, name) {
+        for ( const header of headers ) {
+            if ( header.name.toLowerCase() === name ) {
+                return header.value.trim();
+            }
+        }
+        return '';
+    }
     static canSuspend() {
         return false;
     }
diff --git a/platform/firefox/vapi-background-ext.js b/platform/firefox/vapi-background-ext.js
@@ -110,18 +110,15 @@ vAPI.Net = class extends vAPI.Net {
             details.type = 'image';
             return;
         }
+        if ( type !== 'object' ) { return; }
+        // Try to extract type from response headers if present.
+        if ( details.responseHeaders === undefined ) { return; }
+        const ctype = this.headerValue(details.responseHeaders, 'content-type');
         // https://github.com/uBlockOrigin/uBlock-issues/issues/345
         //   Re-categorize an embedded object as a `sub_frame` if its
         //   content type is that of a HTML document.
-        if ( type === 'object' && Array.isArray(details.responseHeaders) ) {
-            for ( const header of details.responseHeaders ) {
-                if ( header.name.toLowerCase() === 'content-type' ) {
-                    if ( header.value.startsWith('text/html') ) {
-                        details.type = 'sub_frame';
-                    }
-                    break;
-                }
-            }
+        if ( ctype === 'text/html' ) {
+            details.type = 'sub_frame';
         }
     }
 
diff --git a/src/js/pagestore.js b/src/js/pagestore.js
@@ -1019,48 +1019,51 @@ const PageStore = class {
     }
 
     // The caller is responsible to check whether filtering is enabled or not.
-    filterLargeMediaElement(fctxt, size) {
+    filterLargeMediaElement(fctxt, headers) {
         fctxt.filter = undefined;
-
-        if ( this.allowLargeMediaElementsUntil === 0 ) {
+        if ( this.allowLargeMediaElementsUntil === 0 ) { return 0; }
+        if ( sessionSwitches.evaluateZ('no-large-media', fctxt.getTabHostname() ) !== true ) {
+            this.allowLargeMediaElementsUntil = 0;
             return 0;
         }
-        // Disregard large media elements previously allowed: for example, to
-        // seek inside a previously allowed audio/video.
-        if (
-            this.allowLargeMediaElementsRegex instanceof RegExp &&
-            this.allowLargeMediaElementsRegex.test(fctxt.url)
-        ) {
+        // XHR-based streaming is never blocked but we want to prevent autoplay
+        if ( fctxt.itype === fctxt.XMLHTTPREQUEST ) {
+            const ctype = headers.contentType;
+            if ( ctype.startsWith('audio/') || ctype.startsWith('video/') ) {
+                this.largeMediaTimer.on(500);
+            }
             return 0;
         }
         if ( Date.now() < this.allowLargeMediaElementsUntil ) {
-            const sources = this.allowLargeMediaElementsRegex instanceof RegExp
-                ? [ this.allowLargeMediaElementsRegex.source ]
-                : [];
-            sources.push('^' + µb.escapeRegex(fctxt.url));
-            this.allowLargeMediaElementsRegex = new RegExp(sources.join('|'));
+            if ( fctxt.itype === fctxt.MEDIA ) {
+                const sources = this.allowLargeMediaElementsRegex instanceof RegExp
+                    ? [ this.allowLargeMediaElementsRegex.source ]
+                    : [];
+                sources.push('^' + µb.escapeRegex(fctxt.url));
+                this.allowLargeMediaElementsRegex = new RegExp(sources.join('|'));
+            }
             return 0;
         }
+        // Disregard large media elements previously allowed: for example, to
+        // seek inside a previously allowed audio/video.
         if (
-            sessionSwitches.evaluateZ(
-                'no-large-media',
-                fctxt.getTabHostname()
-            ) !== true
+            this.allowLargeMediaElementsRegex instanceof RegExp &&
+            this.allowLargeMediaElementsRegex.test(fctxt.url)
         ) {
-            this.allowLargeMediaElementsUntil = 0;
             return 0;
         }
-        if ( (size >>> 10) < µb.userSettings.largeMediaSize ) {
-            return 0;
+        // Regardless of whether a media is blocked, we want to prevent autoplay
+        if ( fctxt.itype === fctxt.MEDIA ) {
+            this.largeMediaTimer.on(500);
         }
-
+        const size = headers.contentLength;
+        if ( isNaN(size) ) { return 0; }
+        if ( (size >>> 10) < µb.userSettings.largeMediaSize ) { return 0; }
         this.largeMediaCount += 1;
         this.largeMediaTimer.on(500);
-
         if ( logger.enabled ) {
             fctxt.filter = sessionSwitches.toLogData();
         }
-
         return 1;
     }
 
diff --git a/src/js/scriptlets/load-large-media-interactive.js b/src/js/scriptlets/load-large-media-interactive.js
@@ -28,34 +28,26 @@ if ( typeof vAPI !== 'object' || vAPI.loadAllLargeMedia instanceof Function ) {
     return;
 }
 
-/******************************************************************************/
-
 const largeMediaElementAttribute = 'data-' + vAPI.sessionId;
 const largeMediaElementSelector =
     ':root   audio[' + largeMediaElementAttribute + '],\n' +
     ':root     img[' + largeMediaElementAttribute + '],\n' +
     ':root picture[' + largeMediaElementAttribute + '],\n' +
     ':root   video[' + largeMediaElementAttribute + ']';
 
-/******************************************************************************/
+const isMediaElement = elem =>
+    (/^(?:audio|img|picture|video)$/.test(elem.localName));
 
-const isMediaElement = function(elem) {
-    return /^(?:audio|img|picture|video)$/.test(elem.localName);
-};
+const isPlayableMediaElement = elem =>
+    (/^(?:audio|video)$/.test(elem.localName));
 
 /******************************************************************************/
 
 const mediaNotLoaded = function(elem) {
     switch ( elem.localName ) {
     case 'audio':
-    case 'video': {
-        const src = elem.src || '';
-        if ( src.startsWith('blob:') ) {
-            elem.autoplay = false;
-            elem.pause();
-        }
+    case 'video':
         return elem.readyState === 0 || elem.error !== null;
-    }
     case 'img': {
         if ( elem.naturalWidth !== 0 || elem.naturalHeight !== 0 ) {
             break;
@@ -99,29 +91,29 @@ const surveyMissingMediaElements = function() {
     return largeMediaElementCount;
 };
 
-if ( surveyMissingMediaElements() === 0 ) { return; }
-
-// Insert CSS to highlight blocked media elements.
-if ( vAPI.largeMediaElementStyleSheet === undefined ) {
-    vAPI.largeMediaElementStyleSheet = [
-        largeMediaElementSelector + ' {',
-            'border: 2px dotted red !important;',
-            'box-sizing: border-box !important;',
-            'cursor: zoom-in !important;',
-            'display: inline-block;',
-            'filter: none !important;',
-            'font-size: 1rem !important;',
-            'min-height: 1em !important;',
-            'min-width: 1em !important;',
-            'opacity: 1 !important;',
-            'outline: none !important;',
-            'transform: none !important;',
-            'visibility: visible !important;',
-            'z-index: 2147483647',
-        '}',
-    ].join('\n');
-    vAPI.userStylesheet.add(vAPI.largeMediaElementStyleSheet);
-    vAPI.userStylesheet.apply();
+if ( surveyMissingMediaElements() ) {
+    // Insert CSS to highlight blocked media elements.
+    if ( vAPI.largeMediaElementStyleSheet === undefined ) {
+        vAPI.largeMediaElementStyleSheet = [
+            largeMediaElementSelector + ' {',
+                'border: 2px dotted red !important;',
+                'box-sizing: border-box !important;',
+                'cursor: zoom-in !important;',
+                'display: inline-block;',
+                'filter: none !important;',
+                'font-size: 1rem !important;',
+                'min-height: 1em !important;',
+                'min-width: 1em !important;',
+                'opacity: 1 !important;',
+                'outline: none !important;',
+                'transform: none !important;',
+                'visibility: visible !important;',
+                'z-index: 2147483647',
+            '}',
+        ].join('\n');
+        vAPI.userStylesheet.add(vAPI.largeMediaElementStyleSheet);
+        vAPI.userStylesheet.apply();
+    }
 }
 
 /******************************************************************************/
@@ -258,6 +250,27 @@ document.addEventListener('error', onLoadError, true);
 
 /******************************************************************************/
 
+const autoPausedMedia = new WeakMap();
+
+for ( const elem of document.querySelectorAll('audio,video') ) {
+    elem.setAttribute('autoplay', 'false');
+}
+
+const preventAutoplay = function(ev) {
+    const elem = ev.target;
+    if ( isPlayableMediaElement(elem) === false ) { return; }
+    const currentSrc = elem.getAttribute('src') || '';
+    const pausedSrc = autoPausedMedia.get(elem);
+    if ( pausedSrc === currentSrc ) { return; }
+    autoPausedMedia.set(elem, currentSrc);
+    elem.setAttribute('autoplay', 'false');
+    elem.pause();
+};
+
+document.addEventListener('timeupdate', preventAutoplay, true);
+
+/******************************************************************************/
+
 vAPI.loadAllLargeMedia = function() {
     document.removeEventListener('click', onMouseClick, true);
     document.removeEventListener('loadeddata', onLoadedData, true);
diff --git a/src/js/traffic.js b/src/js/traffic.js
