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50 lines
1.3 KiB
50 lines
1.3 KiB
2 years ago
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const LRUCache = require('lru-cache')
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const dns = require('dns')
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const defaultOptions = exports.defaultOptions = {
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family: undefined,
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hints: dns.ADDRCONFIG,
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all: false,
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verbatim: undefined,
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}
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const lookupCache = exports.lookupCache = new LRUCache({ max: 50 })
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// this is a factory so that each request can have its own opts (i.e. ttl)
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// while still sharing the cache across all requests
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exports.getLookup = (dnsOptions) => {
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return (hostname, options, callback) => {
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if (typeof options === 'function') {
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callback = options
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options = null
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} else if (typeof options === 'number') {
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options = { family: options }
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}
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options = { ...defaultOptions, ...options }
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const key = JSON.stringify({
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hostname,
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family: options.family,
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hints: options.hints,
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all: options.all,
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verbatim: options.verbatim,
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})
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if (lookupCache.has(key)) {
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const [address, family] = lookupCache.get(key)
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process.nextTick(callback, null, address, family)
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return
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}
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dnsOptions.lookup(hostname, options, (err, address, family) => {
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if (err) {
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return callback(err)
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}
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lookupCache.set(key, [address, family], { ttl: dnsOptions.ttl })
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return callback(null, address, family)
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})
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}
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}
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