50 lines
1.5 KiB
TypeScript
50 lines
1.5 KiB
TypeScript
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import { createMiddleware } from 'hono/factory'
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import { escape } from './escape'
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/**
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* Converts a list of strings into a regular expression group.
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* Each string in the list is escaped using `RegExp.escape()` or polyfill
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* and then joined by a '|' (OR) operator. The entire result is wrapped in
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* parentheses to form a capturing group.
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*
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* @param list An array of strings to include in the regex.
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* @returns A RegExp matching any of the strings in the capture group.
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*/
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function listToRegex(list: string[]): RegExp | undefined {
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let regex
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if (list.length > 0) {
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const formatted = list.map((item) => escape(item.toUpperCase())).join('|')
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regex = new RegExp(`(${formatted})`)
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}
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return regex
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}
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/**
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*
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* @param params - `blocklist`: An array of user-agents to block, or a RegExp to match against. NOTE: If passing a RegExp, it should match on UPPERCASE User Agents.
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* @returns the Hono middleware to block requests based on User-Agent header.
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*/
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export function uaBlocker(params = { blocklist: [] as string[] | RegExp }) {
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const regex = Array.isArray(params.blocklist) ? listToRegex(params.blocklist) : params.blocklist
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return createMiddleware(async (c, next) => {
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const userAgent = c.req.header('User-Agent')?.toUpperCase()
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if (userAgent && regex && userAgent.match(regex)) {
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return c.text('Forbidden', 403)
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}
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await next()
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return
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})
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}
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export default uaBlocker
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// Export for testing purposes
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export const __test = {
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listToRegex,
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}
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