next.js/test/production/app-dir/subresource-integrity/subresource-integrity.test.ts

import { nextTestSetup } from 'e2e-utils'
import crypto from 'crypto'
import path from 'path'
import cheerio from 'cheerio'

// This test suite is skipped with Turbopack because it's testing an experimental feature. To be implemented after stable.
;(process.env.IS_TURBOPACK_TEST ? describe.skip : describe)(
  'Subresource Integrity',
  () => {
    describe.each(['node', 'edge', 'pages'] as const)(
      'with %s runtime',
      (runtime) => {
        const { next } = nextTestSetup({
          files: path.join(__dirname, 'fixture'),
        })

        function fetchWithPolicy(policy: string | null, reportOnly?: boolean) {
          const cspKey = reportOnly
            ? 'Content-Security-Policy-Report-Only'
            : 'Content-Security-Policy'
          return next.fetch(`/${runtime}`, {
            headers: policy
              ? {
                  [cspKey]: policy,
                }
              : {},
          })
        }

        async function renderWithPolicy(
          policy: string | null,
          reportOnly?: boolean
        ) {
          const res = await fetchWithPolicy(policy, reportOnly)

          expect(res.ok).toBe(true)

          const html = await res.text()

          return cheerio.load(html)
        }

        it('does not include nonce when not enabled', async () => {
          const policies = [
            `script-src 'nonce-'`, // invalid nonce
            'style-src "nonce-cmFuZG9tCg=="', // no script or default src
            '', // empty string
          ]

          for (const policy of policies) {
            const $ = await renderWithPolicy(policy)

            // Find all the script tags without src attributes and with nonce
            // attributes.
            const elements = $('script[nonce]:not([src])')

            // Expect there to be none.
            expect(elements.length).toBe(0)
          }
        })

        it('includes a nonce value with inline scripts when Content-Security-Policy header is defined', async () => {
          // A random nonce value, base64 encoded.
          const nonce = 'cmFuZG9tCg=='

          // Validate all the cases where we could parse the nonce.
          const policies = [
            `script-src 'nonce-${nonce}'`, // base case
            `   script-src   'nonce-${nonce}' `, // extra space added around sources and directive
            `style-src 'self'; script-src 'nonce-${nonce}'`, // extra directives
            `script-src 'self' 'nonce-${nonce}' 'nonce-othernonce'`, // extra nonces
            `default-src 'nonce-othernonce'; script-src 'nonce-${nonce}';`, // script and then fallback case
            `default-src 'nonce-${nonce}'`, // fallback case
          ]

          for (const policy of policies) {
            const $ = await renderWithPolicy(policy)

            // Find all the script tags without src attributes.
            const elements = $('script:not([src])')

            // Expect there to be at least 1 script tag without a src attribute.
            expect(elements.length).toBeGreaterThan(0)

            // Expect all inline scripts to have the nonce value.
            elements.each((i, el) => {
              expect(el.attribs['nonce']).toBe(nonce)
            })
          }
        })

        it('includes a nonce value with inline scripts when Content-Security-Policy-Report-Only header is defined', async () => {
          // A random nonce value, base64 encoded.
          const nonce = 'cmFuZG9tCg=='

          // Validate all the cases where we could parse the nonce.
          const policies = [
            `script-src 'nonce-${nonce}'`, // base case
            `   script-src   'nonce-${nonce}' `, // extra space added around sources and directive
            `style-src 'self'; script-src 'nonce-${nonce}'`, // extra directives
            `script-src 'self' 'nonce-${nonce}' 'nonce-othernonce'`, // extra nonces
            `default-src 'nonce-othernonce'; script-src 'nonce-${nonce}';`, // script and then fallback case
            `default-src 'nonce-${nonce}'`, // fallback case
          ]

          for (const policy of policies) {
            const $ = await renderWithPolicy(policy, true)

            // Find all the script tags without src attributes.
            const elements = $('script:not([src])')

            // Expect there to be at least 1 script tag without a src attribute.
            expect(elements.length).toBeGreaterThan(0)

            // Expect all inline scripts to have the nonce value.
            elements.each((i, el) => {
              expect(el.attribs['nonce']).toBe(nonce)
            })
          }
        })

        it('includes a nonce value with bootstrap scripts when Content-Security-Policy header is defined', async () => {
          // A random nonce value, base64 encoded.
          const nonce = 'cmFuZG9tCg=='

          // Validate all the cases where we could parse the nonce.
          const policies = [
            `script-src 'nonce-${nonce}'`, // base case
            `   script-src   'nonce-${nonce}' `, // extra space added around sources and directive
            `style-src 'self'; script-src 'nonce-${nonce}'`, // extra directives
            `script-src 'self' 'nonce-${nonce}' 'nonce-othernonce'`, // extra nonces
            `default-src 'nonce-othernonce'; script-src 'nonce-${nonce}';`, // script and then fallback case
            `default-src 'nonce-${nonce}'`, // fallback case
          ]

          for (const policy of policies) {
            const $ = await renderWithPolicy(policy)

            // Find all the script tags without src attributes.
            const elements = $('script[src]')

            // Expect there to be at least 2 script tag with a src attribute.
            // The main chunk and the webpack runtime.
            expect(elements.length).toBeGreaterThan(1)

            // Expect all inline scripts to have the nonce value.
            elements.each((i, el) => {
              expect(el.attribs['nonce']).toBe(nonce)
            })
          }
        })

        it('includes an integrity attribute on scripts', async () => {
          // pages router doesn't do integrity attribute yet
          if (runtime === 'pages') return

          const $ = await next.render$(`/${runtime}`)
          // Currently webpack chunks loaded via flight runtime do not get integrity
          // hashes. This was previously unobservable in this test because these scripts
          // are inserted by the webpack runtime and immediately removed from the document.
          // However with the advent of preinitialization of chunks used during SSR there are
          // some script tags for flight loaded chunks that will be part of the initial HTML
          // but do not have integrity hashes. Flight does not currently support a way to
          // provide integrity hashes for these chunks. When this is addressed in React upstream
          // we can revisit this tests assertions and start to ensure it actually applies to
          // all SSR'd scripts. For now we will look for known entrypoint scripts and assume
          // everything else in the <head> is part of flight loaded chunks

          // Collect all the scripts with integrity hashes so we can verify them.
          const files: Map<string, string> = new Map()

          function assertHasIntegrity(el: CheerioElement) {
            const integrity = el.attribs['integrity']
            expect(integrity).toBeDefined()
            expect(integrity).toStartWith('sha256-')

            const src = el.attribs['src']
            expect(src).toBeDefined()

            files.set(src, integrity)
          }

          // <head> scripts are most entrypoint scripts, polyfills, and flight loaded scripts.
          // Since we currently cannot assert integrity on flight loaded scripts (they do not have it)
          // We have to target specific expected entrypoint/polyfill scripts and assert them directly
          const mainScript = $(
            `head script[src^="/_next/static/chunks/main-app"]`
          )
          expect(mainScript.length).toBe(1)
          assertHasIntegrity(mainScript.get(0))

          const polyfillsScript = $(
            'head script[src^="/_next/static/chunks/polyfills"]'
          )
          expect(polyfillsScript.length).toBe(1)
          assertHasIntegrity(polyfillsScript.get(0))

          // body scripts should include just the bootstrap script. We assert that all body
          // scripts have integrity because we don't expect any flight loaded scripts to appear
          // here
          const bodyScripts = $('body script[src]')
          expect(bodyScripts.length).toBeGreaterThan(0)
          bodyScripts.each((i, el) => {
            assertHasIntegrity(el)
          })

          // For each script tag, ensure that the integrity attribute is the
          // correct hash of the script tag.
          for (const [src, integrity] of files) {
            const res = await next.fetch(src)
            expect(res.status).toBe(200)
            const content = await res.text()

            const hash = crypto
              .createHash('sha256')
              .update(content)
              .digest()
              .toString('base64')

            expect(integrity).toEndWith(hash)
          }
        })

        it('throws when escape characters are included in nonce', async () => {
          const res = await fetchWithPolicy(
            `script-src 'nonce-"><script></script>"'`
          )

          if (runtime === 'node' && process.env.__NEXT_EXPERIMENTAL_PPR) {
            expect(res.status).toBe(200)
          } else {
            expect(res.status).toBe(500)
          }
        })
      }
    )
  }
)