Files
documenso/packages/lib/utils/sanitize-branding-css.test.ts
Lucas Smith 0b86ece1d5 feat: add custom branding for signing pages (#2785)
Platform-plan organisations and teams can now customise non-embed
signing pages with six brand colour tokens, a border-radius, and
a free-text custom CSS block (up to 256 KB).

- Stored on OrganisationGlobalSettings / TeamGlobalSettings;
  teams inherit from the org via brandingEnabled === null.
- CSS is sanitised on save (PostCSS) so we can inline it at SSR
  with no per-render parsing.
- Rendered via a nonce'd <style> scoped under .documenso-branded,
  using native CSS nesting so user selectors don't need scoping.
- Gated on the existing embedSigningWhiteLabel claim (or
  self-hosted) — reuses the embed white-label decision.
2026-05-11 13:03:02 +10:00

437 lines
15 KiB
TypeScript

import { describe, expect, it } from 'vitest';
import { sanitizeBrandingCss } from './sanitize-branding-css';
const normalize = (css: string) => css.replace(/\s+/g, ' ').trim();
/**
* The sanitiser does NOT scope selectors. Scoping is applied at render time
* by wrapping the entire sanitised output in `.documenso-branded { ... }` via
* native CSS nesting (see `RecipientBranding`). These tests assert that
* selectors are preserved verbatim and only validated.
*/
describe('sanitizeBrandingCss', () => {
describe('empty input', () => {
it('returns empty output for an empty string', () => {
const result = sanitizeBrandingCss('');
expect(result.css).toBe('');
expect(result.warnings).toEqual([]);
});
it('returns empty output for whitespace-only input', () => {
const result = sanitizeBrandingCss(' \n\t \n');
expect(result.css).toBe('');
expect(result.warnings).toEqual([]);
});
});
describe('selector preservation', () => {
it('preserves a bare class selector', () => {
const result = sanitizeBrandingCss('.foo { color: red; }');
expect(normalize(result.css)).toBe('.foo { color: red; }');
expect(result.warnings).toEqual([]);
});
it('preserves a tag selector', () => {
const result = sanitizeBrandingCss('h1 { color: red; }');
expect(normalize(result.css)).toBe('h1 { color: red; }');
expect(result.warnings).toEqual([]);
});
it('preserves combinators', () => {
const result = sanitizeBrandingCss('.a > .b + .c ~ .d { color: red; }');
expect(normalize(result.css)).toBe('.a > .b + .c ~ .d { color: red; }');
expect(result.warnings).toEqual([]);
});
it('preserves comma-separated selectors', () => {
const result = sanitizeBrandingCss('.a, .b { color: red; }');
expect(normalize(result.css)).toBe('.a, .b { color: red; }');
expect(result.warnings).toEqual([]);
});
it('preserves body/html/:root verbatim (will no-op once nested at render)', () => {
const result = sanitizeBrandingCss('body { background: black; }');
// Selector is left as-is. At render time this becomes
// `.documenso-branded body { ... }`, which won't match anything since
// <body> is an ancestor of the wrapper. Documented tradeoff.
expect(normalize(result.css)).toBe('body { background: black; }');
expect(result.warnings).toEqual([]);
});
});
describe('pseudo-elements', () => {
it('drops a rule containing ::before', () => {
const result = sanitizeBrandingCss(".foo::before { content: 'x'; }");
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('selector');
});
it('drops a rule containing ::after', () => {
const result = sanitizeBrandingCss(".foo::after { content: 'x'; }");
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
});
it('drops a rule containing ::backdrop', () => {
const result = sanitizeBrandingCss('.foo::backdrop { color: red; }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
});
it('drops a rule containing ::marker', () => {
const result = sanitizeBrandingCss('li::marker { color: red; }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
});
it('drops a rule using legacy single-colon :before', () => {
const result = sanitizeBrandingCss(".foo:before { content: 'x'; }");
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('selector');
});
it('drops a rule using legacy single-colon :after', () => {
const result = sanitizeBrandingCss(".foo:after { content: 'x'; }");
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
});
it('keeps ::placeholder verbatim', () => {
const result = sanitizeBrandingCss('input::placeholder { color: gray; }');
expect(normalize(result.css)).toBe('input::placeholder { color: gray; }');
expect(result.warnings).toEqual([]);
});
it('keeps ::selection verbatim', () => {
const result = sanitizeBrandingCss('p::selection { background: yellow; }');
expect(normalize(result.css)).toBe('p::selection { background: yellow; }');
expect(result.warnings).toEqual([]);
});
});
describe('universal selector', () => {
it('drops a bare * selector rule', () => {
const result = sanitizeBrandingCss('* { color: red; }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('selector');
});
it('drops a rule with * combined with descendant', () => {
const result = sanitizeBrandingCss('* .x { color: red; }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
});
it('keeps attribute selectors that include * inside', () => {
const result = sanitizeBrandingCss('[class*="foo"] { color: red; }');
expect(normalize(result.css)).toBe('[class*="foo"] { color: red; }');
expect(result.warnings).toEqual([]);
});
});
describe('blocked properties', () => {
const blockedProperties = [
'display',
'visibility',
'opacity',
'pointer-events',
'position',
'inset',
'top',
'right',
'bottom',
'left',
'z-index',
'transform',
'clip',
'clip-path',
'mask',
'mask-image',
'content',
'width',
'height',
'min-width',
'min-height',
'max-width',
'max-height',
'overflow',
'overflow-x',
'overflow-y',
'font-size',
'letter-spacing',
'word-spacing',
'line-height',
'text-indent',
];
for (const prop of blockedProperties) {
it(`strips the "${prop}" property`, () => {
const result = sanitizeBrandingCss(`.x { ${prop}: 10px; color: red; }`);
expect(result.css).not.toContain(`${prop}:`);
expect(result.css).toContain('color: red');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('property');
expect(result.warnings[0].detail).toContain(prop);
});
}
it('is case-insensitive on property names', () => {
const result = sanitizeBrandingCss('.x { DISPLAY: none; color: red; }');
expect(result.css).not.toMatch(/display/i);
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('property');
});
const allowedProperties: Array<[string, string]> = [
['color', 'red'],
['background', '#fff'],
['border', '1px solid black'],
['border-radius', '4px'],
['font-family', 'sans-serif'],
['font-weight', '600'],
];
for (const [prop, value] of allowedProperties) {
it(`keeps the "${prop}" property`, () => {
const result = sanitizeBrandingCss(`.x { ${prop}: ${value}; }`);
expect(result.css).toContain(`${prop}: ${value}`);
expect(result.warnings).toEqual([]);
});
}
});
describe('blocked values', () => {
it('drops a declaration containing url(', () => {
const result = sanitizeBrandingCss('.x { background: url(http://evil); }');
expect(result.css).not.toContain('url(');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('value');
});
it('drops a declaration containing expression(', () => {
const result = sanitizeBrandingCss('.x { background: expression(alert(1)); }');
expect(result.css).not.toContain('expression(');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('value');
});
it('drops a declaration containing javascript: in a quoted value', () => {
// PostCSS would throw on bare `javascript:alert(1)` (looks like a
// malformed selector inside a declaration). Use a quoted value to
// exercise the substring match cleanly.
const result = sanitizeBrandingCss('.x { font-family: "javascript:alert"; }');
expect(result.css).not.toContain('javascript:');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('value');
});
});
describe('!important stripping', () => {
it('strips !important from a retained declaration', () => {
const result = sanitizeBrandingCss('.x { color: red !important; }');
expect(result.css).not.toContain('!important');
expect(result.css).toContain('color: red');
expect(result.warnings).toEqual([]);
});
});
describe('at-rules', () => {
it('drops @import', () => {
const result = sanitizeBrandingCss('@import url("https://evil.example/x.css");');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('at-rule');
});
it('drops @font-face', () => {
const result = sanitizeBrandingCss('@font-face { font-family: "X"; src: url("x.woff2"); }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('at-rule');
});
it('drops @keyframes', () => {
const result = sanitizeBrandingCss('@keyframes spin { to { transform: rotate(360deg); } }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('at-rule');
});
it('drops @supports', () => {
const result = sanitizeBrandingCss('@supports (display: grid) { .x { color: red; } }');
expect(result.css.trim()).toBe('');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('at-rule');
});
it('keeps @media with min-width and preserves inner selectors verbatim', () => {
const result = sanitizeBrandingCss('@media (min-width: 600px) { .x { color: red; } }');
expect(normalize(result.css)).toBe('@media (min-width: 600px) { .x { color: red; } }');
expect(result.warnings).toEqual([]);
});
it('keeps @media with prefers-color-scheme and preserves body inside', () => {
const result = sanitizeBrandingCss('@media (prefers-color-scheme: dark) { body { background: black; } }');
expect(normalize(result.css)).toBe('@media (prefers-color-scheme: dark) { body { background: black; } }');
expect(result.warnings).toEqual([]);
});
it('strips blocked properties inside @media', () => {
const result = sanitizeBrandingCss('@media (min-width: 600px) { .x { display: none; color: red; } }');
expect(result.css).not.toContain('display');
expect(result.css).toContain('color: red');
expect(result.warnings).toHaveLength(1);
expect(result.warnings[0].kind).toBe('property');
});
});
describe('combined input', () => {
it('keeps valid rules verbatim and reports each drop', () => {
const input = `
.ok { color: red !important; }
.bad-prop { display: none; background: blue; }
.bad-pseudo::before { content: 'x'; }
* { color: red; }
@import "evil.css";
body { background: black; }
@media (min-width: 600px) {
.responsive { color: green; }
}
`;
const result = sanitizeBrandingCss(input);
// Valid bits present, unchanged.
expect(result.css).toContain('.ok');
expect(result.css).toContain('color: red');
expect(result.css).toContain('.bad-prop');
expect(result.css).toContain('background: blue');
expect(result.css).toContain('body { background: black');
expect(result.css).toContain('@media (min-width: 600px)');
expect(result.css).toContain('.responsive');
// Invalid bits gone.
expect(result.css).not.toContain('!important');
expect(result.css).not.toContain('display');
expect(result.css).not.toContain('::before');
expect(result.css).not.toContain('@import');
// Warning kinds.
const kinds = result.warnings.map((w) => w.kind).sort();
expect(kinds).toEqual(['at-rule', 'property', 'selector', 'selector'].sort());
});
});
describe('style-close-tag defence', () => {
// The sanitised output is inlined into a `<style>` element via SSR. The
// browser's HTML parser terminates the element on a literal `</style`
// anywhere in the content. PostCSS's serializer normally escapes `<` to
// `\3c` whenever it would form `</...`, so the literal sequence should
// never reach the output for any of these inputs. These tests pin that
// invariant.
it('escapes </style> inside a string value', () => {
const result = sanitizeBrandingCss('.x { font-family: "</style><img src=x onerror=alert(1)>"; }');
expect(result.css.toLowerCase()).not.toContain('</style');
// Whatever else happens, the canonical close-tag bytes must not appear.
});
it('escapes </style> inside a CSS comment', () => {
const result = sanitizeBrandingCss('.x { color: red; /* </style><script>alert(1)</script> */ }');
expect(result.css.toLowerCase()).not.toContain('</style');
});
it('escapes </style> inside an at-rule params block', () => {
const result = sanitizeBrandingCss(
'@media screen and (foo: bar)</style><script>x()</script> { .x { color: red; } }',
);
expect(result.css.toLowerCase()).not.toContain('</style');
});
it('escapes mixed-case </StYlE> in a value', () => {
const result = sanitizeBrandingCss('.x { font-family: "</StYlE>foo"; }');
expect(result.css.toLowerCase()).not.toContain('</style');
});
it('escapes </style> in an attribute selector value', () => {
const result = sanitizeBrandingCss('[data-x="</style><script>alert(1)</script>"] { color: red; }');
expect(result.css.toLowerCase()).not.toContain('</style');
});
it('preserves benign < not followed by /', () => {
// `<script>` (no slash) is not a tag close; PostCSS leaves it as text
// and the HTML parser treats it as text inside <style> rawtext mode.
const result = sanitizeBrandingCss('.x { font-family: "<script>alert(1)</script>"; }');
// The output keeps the literal `<script>` (harmless) but escapes the
// `</script>` end tag's `<` for the same reason it'd escape `</style>`.
expect(result.css).toContain('<script>');
expect(result.css.toLowerCase()).not.toContain('</style');
});
});
describe('malformed CSS', () => {
// PostCSS is forgiving; an empty value parses without throwing.
it('handles a declaration with an empty value gracefully', () => {
const result = sanitizeBrandingCss('.x { color: }');
expect(result.warnings.filter((w) => w.kind === 'parse-error')).toEqual([]);
expect(result.css).toContain('.x');
});
it('reports a parse-error for clearly broken CSS', () => {
// Unclosed brace.
const result = sanitizeBrandingCss('.x { color: red');
// PostCSS may or may not throw on this; if it does, we get a
// parse-error warning. If it tolerates it, the rule is sanitized.
if (result.css === '') {
expect(result.warnings.some((w) => w.kind === 'parse-error')).toBe(true);
} else {
expect(result.css).toContain('.x');
}
});
});
});