Katia Bulatova
502e1bde07
Model-authored markdown could emit a remote image whose URL the browser fetches on render — a zero-click data beacon. Constrain the shared markdown renderer with a urlTransform that strips the src of any non-local image and limits links to safe schemes.
63 lines
2.5 KiB
TypeScript
63 lines
2.5 KiB
TypeScript
import { lazy } from "react";
|
|
import type { CodeHighlighterPlugin, UrlTransform } from "streamdown";
|
|
|
|
const SAFE_LINK_SCHEMES = new Set(["http:", "https:", "mailto:"]);
|
|
|
|
/**
|
|
* URL policy for model-authored markdown. A remote image is fetched the moment it
|
|
* renders — no click — so it is a zero-click data beacon; we drop the src of any
|
|
* non-local image. Links stay clickable but only for safe, human-followable schemes.
|
|
* streamdown removes an attribute whose transform returns undefined, so no request fires.
|
|
*/
|
|
export const restrictModelUrls: UrlTransform = (url, key, node) => {
|
|
const value = url.trim();
|
|
const isImage = node.tagName === "img" || key === "src" || key === "srcset";
|
|
|
|
if (isImage) {
|
|
// Inline images carry their own bytes; a relative path resolves to our own origin.
|
|
if (/^data:/i.test(value) || /^blob:/i.test(value)) return url;
|
|
// Absolute or protocol-relative means a remote host — strip it so nothing is fetched.
|
|
if (/^[a-z][a-z0-9+.-]*:/i.test(value) || value.startsWith("//")) return undefined;
|
|
return url;
|
|
}
|
|
|
|
// Links: relative and protocol-relative are fine; otherwise require a safe scheme.
|
|
if (value.startsWith("//")) return url;
|
|
const schemeMatch = /^([a-z][a-z0-9+.-]*):/i.exec(value);
|
|
if (!schemeMatch) return url;
|
|
return SAFE_LINK_SCHEMES.has(`${schemeMatch[1].toLowerCase()}:`) ? url : undefined;
|
|
};
|
|
|
|
export const StreamdownRenderer = lazy(() =>
|
|
Promise.all([import("streamdown"), import("@streamdown/code"), import("./shikiTheme")]).then(
|
|
([{ Streamdown }, { createCodePlugin }, { triggerDarkTheme }]) => {
|
|
// Type assertion needed: @streamdown/code and streamdown resolve different shiki
|
|
// versions under pnpm, causing structurally-identical CodeHighlighterPlugin types
|
|
// to be considered incompatible (different BundledLanguage string unions).
|
|
const codePlugin = createCodePlugin({
|
|
themes: [triggerDarkTheme, triggerDarkTheme],
|
|
}) as unknown as CodeHighlighterPlugin;
|
|
|
|
return {
|
|
default: ({
|
|
children,
|
|
isAnimating = false,
|
|
}: {
|
|
children: string;
|
|
isAnimating?: boolean;
|
|
}) => (
|
|
<Streamdown
|
|
isAnimating={isAnimating}
|
|
plugins={{ code: codePlugin }}
|
|
controls={{ code: { copy: false, download: false } }}
|
|
urlTransform={restrictModelUrls}
|
|
linkSafety={{ enabled: false }}
|
|
>
|
|
{children}
|
|
</Streamdown>
|
|
),
|
|
};
|
|
}
|
|
)
|
|
);
|