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This patch refactors the DNS default resolver code to make it easier to be included in a snapshot: - The code specific for the callback-based DNS resolver are not in a separate module to make the dependency clearer (it's not actually needed if the user only ever loads `dns/promises`) - The common part of the callback-based resolver and the promise- based resolver is now ResolverBase. The other two user-facing resolvers are now subclasses of ResolverBase. The default Resolver is constructed with just ResolverBase. This would be fine as the default resolver is never actually exposed to the user-land and it has been working using duck-typing anyway. - Move the construction of Resolver subclasses into a common method `createResolverClass()` to reduce code duplication. The two subclasses now also share the same base constructor. This would make it possible for them to also share code for snapshot support later. - `--dns-result-order` is now queried and refreshed during pre-execution. To avoid loading the cares_wrap binding unnecessarily the loading of the binding is also made lazy. PR-URL: #44541 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Zeyu "Alex" Yang <himself65@outlook.com> Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,116 @@ | ||
| 'use strict'; | ||
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|
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| const { | ||
| ObjectDefineProperty, | ||
| ReflectApply, | ||
| ArrayPrototypeMap, | ||
| Symbol | ||
| } = primordials; | ||
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| const { toASCII } = require('internal/idna'); | ||
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| const { | ||
| codes: { | ||
| ERR_INVALID_ARG_TYPE, | ||
| ERR_INVALID_ARG_VALUE, | ||
| }, | ||
| dnsException | ||
| } = require('internal/errors'); | ||
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| const { | ||
| createResolverClass, | ||
| } = require('internal/dns/utils'); | ||
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| const { | ||
| validateFunction, | ||
| validateString, | ||
| } = require('internal/validators'); | ||
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| const { | ||
| QueryReqWrap, | ||
| } = internalBinding('cares_wrap'); | ||
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| const { | ||
| hasObserver, | ||
| startPerf, | ||
| stopPerf, | ||
| } = require('internal/perf/observe'); | ||
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| const kPerfHooksDnsLookupResolveContext = Symbol('kPerfHooksDnsLookupResolveContext'); | ||
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| function onresolve(err, result, ttls) { | ||
| if (ttls && this.ttl) | ||
| result = ArrayPrototypeMap( | ||
| result, (address, index) => ({ address, ttl: ttls[index] })); | ||
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| if (err) | ||
| this.callback(dnsException(err, this.bindingName, this.hostname)); | ||
| else { | ||
| this.callback(null, result); | ||
| if (this[kPerfHooksDnsLookupResolveContext] && hasObserver('dns')) { | ||
| stopPerf(this, kPerfHooksDnsLookupResolveContext, { detail: { result } }); | ||
| } | ||
| } | ||
| } | ||
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| function resolver(bindingName) { | ||
| function query(name, /* options, */ callback) { | ||
| let options; | ||
| if (arguments.length > 2) { | ||
| options = callback; | ||
| callback = arguments[2]; | ||
| } | ||
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| validateString(name, 'name'); | ||
| validateFunction(callback, 'callback'); | ||
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| const req = new QueryReqWrap(); | ||
| req.bindingName = bindingName; | ||
| req.callback = callback; | ||
| req.hostname = name; | ||
| req.oncomplete = onresolve; | ||
| req.ttl = !!(options && options.ttl); | ||
| const err = this._handle[bindingName](req, toASCII(name)); | ||
| if (err) throw dnsException(err, bindingName, name); | ||
| if (hasObserver('dns')) { | ||
| startPerf(req, kPerfHooksDnsLookupResolveContext, { | ||
| type: 'dns', | ||
| name: bindingName, | ||
| detail: { | ||
| host: name, | ||
| ttl: req.ttl, | ||
| }, | ||
| }); | ||
| } | ||
| return req; | ||
| } | ||
| ObjectDefineProperty(query, 'name', { __proto__: null, value: bindingName }); | ||
| return query; | ||
| } | ||
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| // This is the callback-based resolver. There is another similar | ||
| // resolver in dns/promises.js with resolve methods that are based | ||
| // on promises instead. | ||
| const { Resolver, resolveMap } = createResolverClass(resolver); | ||
| Resolver.prototype.resolve = resolve; | ||
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| function resolve(hostname, rrtype, callback) { | ||
| let resolver; | ||
| if (typeof rrtype === 'string') { | ||
| resolver = resolveMap[rrtype]; | ||
| } else if (typeof rrtype === 'function') { | ||
| resolver = resolveMap.A; | ||
| callback = rrtype; | ||
| } else { | ||
| throw new ERR_INVALID_ARG_TYPE('rrtype', 'string', rrtype); | ||
| } | ||
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| if (typeof resolver === 'function') { | ||
| return ReflectApply(resolver, this, [hostname, callback]); | ||
| } | ||
| throw new ERR_INVALID_ARG_VALUE('rrtype', rrtype); | ||
| } | ||
|
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| module.exports = { | ||
| Resolver | ||
| }; |
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