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Fix(nonce): correctly detect valid script elements #611

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Fix(nonce): correctly detect valid script elements #611

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fdd9059
recursive html parsing
vejja Mar 19, 2025
5b284ac
Replace regex-based parsing with a recursive algorithm to match HTML …
vejja Mar 19, 2025
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50 changes: 32 additions & 18 deletions src/runtime/nitro/plugins/40-cspSsrNonce.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,12 +2,6 @@
import { resolveSecurityRules } from '../context'
import { generateRandomNonce } from '../../../utils/crypto'

const LINK_RE = /<link([^>]*?>)/gi
const NONCE_RE = /nonce="[^"]+"/i
const SCRIPT_RE = /<script([^>]*?>)/gi
const STYLE_RE = /<style([^>]*?>)/gi


/**
* This plugin generates a nonce for the current request and adds it to the HTML.
* It only runs in SSR mode.
Expand Down Expand Up @@ -58,20 +52,11 @@
return element;
}
// Add nonce to all link tags
element = element.replace(LINK_RE, (match, rest) => {
if (NONCE_RE.test(rest)) {
return match.replace(NONCE_RE, `nonce="${nonce}"`);
}
return `<link nonce="${nonce}"` + rest
})
element = addNonceToElement(element, 'link', nonce)
// Add nonce to all script tags
element = element.replace(SCRIPT_RE, (match, rest) => {
return `<script nonce="${nonce}"` + rest
})
element = addNonceToElement(element, 'script', nonce)
// Add nonce to all style tags
element = element.replace(STYLE_RE, (match, rest) => {
return `<style nonce="${nonce}"` + rest
})
element = addNonceToElement(element, 'style', nonce)
return element
})
}
Expand All @@ -84,3 +69,32 @@
}
})
})

function addNonceToElement(element: string, tagName: string, nonce: string): string {
const tagRegex = new RegExp(`<${tagName}([^>]*?)>`, 'gi')
const nonceRegex = /nonce="[^"]+"/i

return element.replace(tagRegex, (match, rest) => {
if (nonceRegex.test(rest)) {
return match.replace(nonceRegex, `nonce="${nonce}"`)
}
return `<${tagName} nonce="${nonce}"${rest}>`
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Copilot AI Mar 20, 2025

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Ensure that a space is preserved between the injected nonce attribute and the rest of the attributes, especially if 'rest' does not start with a space.

Suggested change
return `<${tagName} nonce="${nonce}"${rest}>`
return `<${tagName} nonce="${nonce}"${rest.startsWith(' ') ? rest : ' ' + rest}>`

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})
}

function parseHtmlRecursively(html: string, nonce: string): string {

Check warning on line 85 in src/runtime/nitro/plugins/40-cspSsrNonce.ts

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GitHub Actions / ci (ubuntu-latest, 18) 

'parseHtmlRecursively' is defined but never used
const tagRegex = /<([a-zA-Z]+)([^>]*)>(.*?)<\/\1>/gs
return html.replace(tagRegex, (match, tagName, attributes, innerHtml) => {
const updatedAttributes = addNonceToAttributes(attributes, nonce)
const updatedInnerHtml = parseHtmlRecursively(innerHtml, nonce)
return `<${tagName}${updatedAttributes}>${updatedInnerHtml}</${tagName}>`
})
}

function addNonceToAttributes(attributes: string, nonce: string): string {
const nonceRegex = /nonce="[^"]+"/i
if (nonceRegex.test(attributes)) {
return attributes.replace(nonceRegex, `nonce="${nonce}"`)
}
return ` nonce="${nonce}"${attributes}`
}