fix: nested stylesheets should have absolute URLs

.changeset/six-llamas-brush.md

@@ -0,0 +1,5 @@
+---
+"rrweb-snapshot": patch
+---
+
+Fix `url()` rewrite for nested stylesheets by rewriting during stringification instead of after

packages/rrweb-snapshot/package.json

@@ -10,6 +10,7 @@
     "test:watch": "vitest watch",
     "retest:update": "vitest run --update",
     "test:update": "yarn build && vitest run --update",
+    "bench": "vite build && vitest bench",
     "dev": "vite build --watch",
     "build": "yarn turbo prepublish -F rrweb-snapshot",
     "check-types": "tsc --noEmit",

packages/rrweb-snapshot/src/snapshot.ts

@@ -25,6 +25,7 @@ import {
   getInputType,
   toLowerCase,
   extractFileExtension,
+  absolutifyURLs,
 } from './utils';
 
 let _id = 1;
@@ -53,71 +54,9 @@ function getValidTagName(element: HTMLElement): Lowercase<string> {
   return processedTagName;
 }
 
-function extractOrigin(url: string): string {
-  let origin = '';
-  if (url.indexOf('//') > -1) {
-    origin = url.split('/').slice(0, 3).join('/');
-  } else {
-    origin = url.split('/')[0];
-  }
-  origin = origin.split('?')[0];
-  return origin;
-}
-
 let canvasService: HTMLCanvasElement | null;
 let canvasCtx: CanvasRenderingContext2D | null;
 
-const URL_IN_CSS_REF = /url\((?:(')([^']*)'|(")(.*?)"|([^)]*))\)/gm;
-const URL_PROTOCOL_MATCH = /^(?:[a-z+]+:)?\/\//i;
-const URL_WWW_MATCH = /^www\..*/i;
-const DATA_URI = /^(data:)([^,]*),(.*)/i;
-export function absoluteToStylesheet(
-  cssText: string | null,
-  href: string,
-): string {
-  return (cssText || '').replace(
-    URL_IN_CSS_REF,
-    (
-      origin: string,
-      quote1: string,
-      path1: string,
-      quote2: string,
-      path2: string,
-      path3: string,
-    ) => {
-      const filePath = path1 || path2 || path3;
-      const maybeQuote = quote1 || quote2 || '';
-      if (!filePath) {
-        return origin;
-      }
-      if (URL_PROTOCOL_MATCH.test(filePath) || URL_WWW_MATCH.test(filePath)) {
-        return `url(${maybeQuote}${filePath}${maybeQuote})`;
-      }
-      if (DATA_URI.test(filePath)) {
-        return `url(${maybeQuote}${filePath}${maybeQuote})`;
-      }
-      if (filePath[0] === '/') {
-        return `url(${maybeQuote}${
-          extractOrigin(href) + filePath
-        }${maybeQuote})`;
-      }
-      const stack = href.split('/');
-      const parts = filePath.split('/');
-      stack.pop();
-      for (const part of parts) {
-        if (part === '.') {
-          continue;
-        } else if (part === '..') {
-          stack.pop();
-        } else {
-          stack.push(part);
-        }
-      }
-      return `url(${maybeQuote}${stack.join('/')}${maybeQuote})`;
-    },
-  );
-}
-
 // eslint-disable-next-line no-control-regex
 const SRCSET_NOT_SPACES = /^[^ \t\n\r\u000c]+/; // Don't use \s, to avoid matching non-breaking space
 // eslint-disable-next-line no-control-regex
@@ -254,7 +193,7 @@ export function transformAttribute(
   } else if (name === 'srcset') {
     return getAbsoluteSrcsetString(doc, value);
   } else if (name === 'style') {
-    return absoluteToStylesheet(value, getHref(doc));
+    return absolutifyURLs(value, getHref(doc));
   } else if (tagName === 'object' && name === 'data') {
     return absoluteToDoc(doc, value);
   }
@@ -584,7 +523,7 @@ function serializeTextNode(
         n,
       );
     }
-    textContent = absoluteToStylesheet(textContent, getHref(options.doc));
+    textContent = absolutifyURLs(textContent, getHref(options.doc));
   }
   if (isScript) {
     textContent = 'SCRIPT_PLACEHOLDER';
@@ -664,7 +603,7 @@ function serializeElementNode(
     if (cssText) {
       delete attributes.rel;
       delete attributes.href;
-      attributes._cssText = absoluteToStylesheet(cssText, stylesheet!.href!);
+      attributes._cssText = cssText;
     }
   }
   // dynamic stylesheet
@@ -678,7 +617,7 @@ function serializeElementNode(
       (n as HTMLStyleElement).sheet as CSSStyleSheet,
     );
     if (cssText) {
-      attributes._cssText = absoluteToStylesheet(cssText, getHref(doc));
+      attributes._cssText = cssText;
     }
   }
   // form fields

packages/rrweb-snapshot/src/utils.ts

@@ -96,19 +96,21 @@ export function escapeImportStatement(rule: CSSImportRule): string {
 export function stringifyStylesheet(s: CSSStyleSheet): string | null {
   try {
     const rules = s.rules || s.cssRules;
-    return rules
-      ? fixBrowserCompatibilityIssuesInCSS(
-          Array.from(rules, stringifyRule).join(''),
-        )
-      : null;
+    if (!rules) {
+      return null;
+    }
+    const stringifiedRules = Array.from(rules, (rule: CSSRule) =>
+      stringifyRule(rule, s.href),
+    ).join('');
+    return fixBrowserCompatibilityIssuesInCSS(stringifiedRules);
   } catch (error) {
     return null;
   }
 }
 
-export function stringifyRule(rule: CSSRule): string {
-  let importStringified;
+export function stringifyRule(rule: CSSRule, sheetHref: string | null): string {
   if (isCSSImportRule(rule)) {
+    let importStringified;
     try {
       importStringified =
         // for same-origin stylesheets,
@@ -117,15 +119,25 @@ export function stringifyRule(rule: CSSRule): string {
         // work around browser issues with the raw string `@import url(...)` statement
         escapeImportStatement(rule);
     } catch (error) {
-      // ignore
+      importStringified = rule.cssText;
+    }
+    if (rule.styleSheet.href) {
+      // url()s within the imported stylesheet are relative to _that_ sheet's href
+      return absolutifyURLs(importStringified, rule.styleSheet.href);
+    }
+    return importStringified;
+  } else {
+    let ruleStringified = rule.cssText;
+    if (isCSSStyleRule(rule) && rule.selectorText.includes(':')) {
+      // Safari does not escape selectors with : properly
+      // see https://bugs.webkit.org/show_bug.cgi?id=184604
+      ruleStringified = fixSafariColons(ruleStringified);
     }
-  } else if (isCSSStyleRule(rule) && rule.selectorText.includes(':')) {
-    // Safari does not escape selectors with : properly
-    // see https://bugs.webkit.org/show_bug.cgi?id=184604
-    return fixSafariColons(rule.cssText);
+    if (sheetHref) {
+      return absolutifyURLs(ruleStringified, sheetHref);
+    }
+    return ruleStringified;
   }
-
-  return importStringified || rule.cssText;
 }
 
 export function fixSafariColons(cssStringified: string): string {
@@ -351,3 +363,62 @@ export function extractFileExtension(
   const match = url.pathname.match(regex);
   return match?.[1] ?? null;
 }
+
+function extractOrigin(url: string): string {
+  let origin = '';
+  if (url.indexOf('//') > -1) {
+    origin = url.split('/').slice(0, 3).join('/');
+  } else {
+    origin = url.split('/')[0];
+  }
+  origin = origin.split('?')[0];
+  return origin;
+}
+
+const URL_IN_CSS_REF = /url\((?:(')([^']*)'|(")(.*?)"|([^)]*))\)/gm;
+const URL_PROTOCOL_MATCH = /^(?:[a-z+]+:)?\/\//i;
+const URL_WWW_MATCH = /^www\..*/i;
+const DATA_URI = /^(data:)([^,]*),(.*)/i;
+export function absolutifyURLs(cssText: string | null, href: string): string {
+  return (cssText || '').replace(
+    URL_IN_CSS_REF,
+    (
+      origin: string,
+      quote1: string,
+      path1: string,
+      quote2: string,
+      path2: string,
+      path3: string,
+    ) => {
+      const filePath = path1 || path2 || path3;
+      const maybeQuote = quote1 || quote2 || '';
+      if (!filePath) {
+        return origin;
+      }
+      if (URL_PROTOCOL_MATCH.test(filePath) || URL_WWW_MATCH.test(filePath)) {
+        return `url(${maybeQuote}${filePath}${maybeQuote})`;
+      }
+      if (DATA_URI.test(filePath)) {
+        return `url(${maybeQuote}${filePath}${maybeQuote})`;
+      }
+      if (filePath[0] === '/') {
+        return `url(${maybeQuote}${
+          extractOrigin(href) + filePath
+        }${maybeQuote})`;
+      }
+      const stack = href.split('/');
+      const parts = filePath.split('/');
+      stack.pop();
+      for (const part of parts) {
+        if (part === '.') {
+          continue;
+        } else if (part === '..') {
+          stack.pop();
+        } else {
+          stack.push(part);
+        }
+      }
+      return `url(${maybeQuote}${stack.join('/')}${maybeQuote})`;
+    },
+  );
+}

packages/rrweb-snapshot/test/__snapshots__/integration.test.ts.snap

@@ -489,7 +489,7 @@ exports[`integration tests > [html file]: with-style-sheet.html 1`] = `
   <meta name=\\"viewport\\" content=\\"width=device-width, initial-scale=1.0\\" />
   <meta http-equiv=\\"X-UA-Compatible\\" content=\\"ie=edge\\" />
   <title>with style sheet</title>
-  <style>body { margin: 0px; background: url(\\"http://localhost:3030/a.jpg\\"); border-image: url(\\"data:image/svg+xml;utf8,&lt;svg xmlns=\\\\\\"http://www.w3.org/2000/svg\\\\\\" x=\\\\\\"0px\\\\\\" y=\\\\\\"0px\\\\\\" viewBox=\\\\\\"0 0 256 256\\\\\\"&gt;&lt;g&gt;&lt;g&gt;&lt;polygon points=\\\\\\"79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128\\\\\\"/&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;\\") 100% / 1 / 0 stretch; }p { color: red; background: url(\\"http://localhost:3030/css/b.jpg\\"); }body &gt; p { color: yellow; }</style>
+  <style>body { margin: 0px; background: url(\\"http://localhost:3030/should-be-in-root-folder.jpg\\"); border-image: url(\\"data:image/svg+xml;utf8,&lt;svg xmlns=\\\\\\"http://www.w3.org/2000/svg\\\\\\" x=\\\\\\"0px\\\\\\" y=\\\\\\"0px\\\\\\" viewBox=\\\\\\"0 0 256 256\\\\\\"&gt;&lt;g&gt;&lt;g&gt;&lt;polygon points=\\\\\\"79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128\\\\\\"/&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;\\") 100% / 1 / 0 stretch; }p { color: red; background: url(\\"http://localhost:3030/css/should-be-in-css-folder.jpg\\"); }body &gt; p { color: yellow; }</style>
 </head><body>
 </body></html>"
 `;
@@ -500,7 +500,8 @@ exports[`integration tests > [html file]: with-style-sheet-with-import.html 1`]
   <meta name=\\"viewport\\" content=\\"width=device-width, initial-scale=1.0\\" />
   <meta http-equiv=\\"X-UA-Compatible\\" content=\\"ie=edge\\" />
   <title>with style sheet with import</title>
-  <style>@import url(\\"//fonts.googleapis.com/css2?family=Open+Sans:wght@400;600;700&amp;family=Roboto:wght@100;300;400;500;700&amp;display=swap\\\\\\"\\");body { margin: 0px; background: url(\\"http://localhost:3030/a.jpg\\"); border-image: url(\\"data:image/svg+xml;utf8,&lt;svg xmlns=\\\\\\"http://www.w3.org/2000/svg\\\\\\" x=\\\\\\"0px\\\\\\" y=\\\\\\"0px\\\\\\" viewBox=\\\\\\"0 0 256 256\\\\\\"&gt;&lt;g&gt;&lt;g&gt;&lt;polygon points=\\\\\\"79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128\\\\\\"/&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;\\") 100% / 1 / 0 stretch; }p { color: red; background: url(\\"http://localhost:3030/css/b.jpg\\"); }body &gt; p { color: yellow; }</style>
+  <style>@import url(\\"//fonts.googleapis.com/css2?family=Open+Sans:wght@400;600;700&amp;family=Roboto:wght@100;300;400;500;700&amp;display=swap\\\\\\"\\");body { margin: 0px; background: url(\\"http://localhost:3030/should-be-in-root-folder.jpg\\"); border-image: url(\\"data:image/svg+xml;utf8,&lt;svg xmlns=\\\\\\"http://www.w3.org/2000/svg\\\\\\" x=\\\\\\"0px\\\\\\" y=\\\\\\"0px\\\\\\" viewBox=\\\\\\"0 0 256 256\\\\\\"&gt;&lt;g&gt;&lt;g&gt;&lt;polygon points=\\\\\\"79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128\\\\\\"/&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;\\") 100% / 1 / 0 stretch; }p { color: red; background: url(\\"http://localhost:3030/css/should-be-in-css-folder.jpg\\"); }body &gt; p { color: yellow; }body { margin: 0px; background: url(\\"http://localhost:3030/should-be-in-root-folder.jpg\\"); border-image: url(\\"data:image/svg+xml;utf8,&lt;svg xmlns=\\\\\\"http://www.w3.org/2000/svg\\\\\\" x=\\\\\\"0px\\\\\\" y=\\\\\\"0px\\\\\\" viewBox=\\\\\\"0 0 256 256\\\\\\"&gt;&lt;g&gt;&lt;g&gt;&lt;polygon points=\\\\\\"79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128\\\\\\"/&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;\\") 100% / 1 / 0 stretch; }p { color: red; background: url(\\"http://localhost:3030/alt-css/should-be-in-alt-css-folder.jpg\\"); }body &gt; p { color: yellow; }</style>
+  <style>body { margin: 0px; background: url(\\"http://localhost:3030/should-be-in-root-folder.jpg\\"); border-image: url(\\"data:image/svg+xml;utf8,&lt;svg xmlns=\\\\\\"http://www.w3.org/2000/svg\\\\\\" x=\\\\\\"0px\\\\\\" y=\\\\\\"0px\\\\\\" viewBox=\\\\\\"0 0 256 256\\\\\\"&gt;&lt;g&gt;&lt;g&gt;&lt;polygon points=\\\\\\"79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128\\\\\\"/&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;\\") 100% / 1 / 0 stretch; }p { color: red; background: url(\\"http://localhost:3030/alt-css/should-be-in-alt-css-folder.jpg\\"); }body &gt; p { color: yellow; }section { background: url(\\"http://localhost:3030/should-be-in-root-folder.jpg\\"); }</style>
 </head><body>
 </body></html>"
 `;

packages/rrweb-snapshot/test/alt-css/alt-style.css

@@ -0,0 +1,12 @@
+body {
+    margin: 0;
+    background: url('../should-be-in-root-folder.jpg');
+    border-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" viewBox="0 0 256 256"><g><g><polygon points="79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128"/></g></g></svg>');
+  }
+  p {
+    color: red;
+    background: url('./should-be-in-alt-css-folder.jpg');
+  }
+  body > p {
+    color: yellow;
+  }

packages/rrweb-snapshot/test/css/style-with-import.css

@@ -1,2 +1,3 @@
 @import '//fonts.googleapis.com/css2?family=Open+Sans:wght@400;600;700&family=Roboto:wght@100;300;400;500;700&display=swap"';
 @import './style.css';
+@import '../alt-css/alt-style.css';

packages/rrweb-snapshot/test/css/style.css

@@ -1,11 +1,11 @@
 body {
   margin: 0;
-  background: url('../a.jpg');
+  background: url('../should-be-in-root-folder.jpg');
   border-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" viewBox="0 0 256 256"><g><g><polygon points="79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128"/></g></g></svg>');
 }
 p {
   color: red;
-  background: url('./b.jpg');
+  background: url('./should-be-in-css-folder.jpg');
 }
 body > p {
   color: yellow;

packages/rrweb-snapshot/test/html/with-style-sheet-with-import.html

@@ -7,6 +7,10 @@
   <meta http-equiv="X-UA-Compatible" content="ie=edge">
   <title>with style sheet with import</title>
   <link rel="stylesheet" href="/css/style-with-import.css">
+  <style>
+    @import '../alt-css/alt-style.css';
+    section { background: url('./should-be-in-root-folder.jpg'); }
+  </style>
 </head>
 
 <body>