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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 <[email protected]> Reviewed-By: Zeyu "Alex" Yang <[email protected]> Reviewed-By: Minwoo Jung <[email protected]>
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,116 @@ | ||
'use strict'; | ||
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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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