24 lines
658 B
TypeScript
24 lines
658 B
TypeScript
/**
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* Validates `next` parameter from Vercel callbacks.
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* Only allows vercel.com subdomains (the expected source) and same-origin relative paths.
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*/
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export function sanitizeVercelNextUrl(url: string | undefined | null): string | undefined {
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if (!url) return undefined;
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// Allow relative paths (same-origin) but reject protocol-relative URLs
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if (url.startsWith("/") && !url.startsWith("//")) {
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return url;
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}
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try {
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const parsed = new URL(url);
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if (parsed.protocol === "https:" && /^([a-z0-9-]+\.)*vercel\.com$/i.test(parsed.hostname)) {
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return parsed.toString();
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}
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} catch {
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// Invalid URL
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}
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return undefined;
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}
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