1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
| 'use strict'
|
| const { LRUCache } = require('lru-cache')
| const dns = require('dns')
|
| // this is a factory so that each request can have its own opts (i.e. ttl)
| // while still sharing the cache across all requests
| const cache = new LRUCache({ max: 50 })
|
| const getOptions = ({
| family = 0,
| hints = dns.ADDRCONFIG,
| all = false,
| verbatim = undefined,
| ttl = 5 * 60 * 1000,
| lookup = dns.lookup,
| }) => ({
| // hints and lookup are returned since both are top level properties to (net|tls).connect
| hints,
| lookup: (hostname, ...args) => {
| const callback = args.pop() // callback is always last arg
| const lookupOptions = args[0] ?? {}
|
| const options = {
| family,
| hints,
| all,
| verbatim,
| ...(typeof lookupOptions === 'number' ? { family: lookupOptions } : lookupOptions),
| }
|
| const key = JSON.stringify({ hostname, ...options })
|
| if (cache.has(key)) {
| const cached = cache.get(key)
| return process.nextTick(callback, null, ...cached)
| }
|
| lookup(hostname, options, (err, ...result) => {
| if (err) {
| return callback(err)
| }
|
| cache.set(key, result, { ttl })
| return callback(null, ...result)
| })
| },
| })
|
| module.exports = {
| cache,
| getOptions,
| }
|
|
