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fix(dry): DRYing up the resolvers. #102

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6d9612d
chore(pkg): ⬆️ Upgrading Aegir and Sinon
whizzzkid Oct 26, 2023
166dfa3
Merge branch 'main' into fix/dry-code
whizzzkid Oct 26, 2023
4c1d440
fix(dry): 🎨 DRYing up the resolvers.
whizzzkid Oct 27, 2023
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145 changes: 56 additions & 89 deletions src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,20 @@ interface ResolverOptions {
request?: Request
}

type RecordTypes = 'A' | 'AAAA' | 'TXT'

interface DNSResolver<T> {
hostname: string
recordType: RecordTypes
cache?: Receptacle<T[], undefined>
}

const RECORD_EXTRACTORS: Record<RecordTypes, (input: DNSJSON['Answer'][0]) => string | string[]> = {
A: ({ data }): string => data,
AAAA: ({ data }): string => data,
TXT: ({ data }): string[] => [data.replace(/['"]+/g, '')]
}

/**
* DNS over HTTP resolver.
* Uses a list of servers to resolve DNS records with HTTP requests.
Expand Down Expand Up @@ -112,48 +126,10 @@ class Resolver {
* @param {string} hostname - host name to resolve
*/
async resolve4 (hostname: string): Promise<string[]> {
const recordType = 'A'
const cached = this._cache.get(utils.getCacheKey(hostname, recordType))
if (cached != null) {
return cached
}
let aborted = false

for (const server of this._getShuffledServers()) {
const controller = new AbortController()
this._abortControllers.push(controller)

try {
const response = await this._request(utils.buildResource(
server,
hostname,
recordType
), controller.signal)

const data = response.Answer.map(a => a.data)
const ttl = Math.min(...response.Answer.map(a => a.TTL))

this._cache.set(utils.getCacheKey(hostname, recordType), data, { ttl })

return data
} catch (err) {
if (controller.signal.aborted) {
aborted = true
}

log.error(`${server} could not resolve ${hostname} record ${recordType}`)
} finally {
this._abortControllers = this._abortControllers.filter(c => c !== controller)
}
}

if (aborted) {
throw Object.assign(new Error('queryA ECANCELLED'), {
code: 'ECANCELLED'
})
}

throw new Error(`Could not resolve ${hostname} record ${recordType}`)
return this.resolveAny({
hostname,
recordType: 'A'
})
}

/**
Expand All @@ -162,48 +138,10 @@ class Resolver {
* @param {string} hostname - host name to resolve
*/
async resolve6 (hostname: string): Promise<string[]> {
const recordType = 'AAAA'
const cached = this._cache.get(utils.getCacheKey(hostname, recordType))
if (cached != null) {
return cached
}
let aborted = false

for (const server of this._getShuffledServers()) {
const controller = new AbortController()
this._abortControllers.push(controller)

try {
const response = await this._request(utils.buildResource(
server,
hostname,
recordType
), controller.signal)

const data = response.Answer.map(a => a.data)
const ttl = Math.min(...response.Answer.map(a => a.TTL))

this._cache.set(utils.getCacheKey(hostname, recordType), data, { ttl })

return data
} catch (err) {
if (controller.signal.aborted) {
aborted = true
}

log.error(`${server} could not resolve ${hostname} record ${recordType}`)
} finally {
this._abortControllers = this._abortControllers.filter(c => c !== controller)
}
}

if (aborted) {
throw Object.assign(new Error('queryAaaa ECANCELLED'), {
code: 'ECANCELLED'
})
}

throw new Error(`Could not resolve ${hostname} record ${recordType}`)
return this.resolveAny({
hostname,
recordType: 'AAAA'
})
}

/**
Expand All @@ -212,8 +150,34 @@ class Resolver {
* @param {string} hostname - host name to resolve
*/
async resolveTxt (hostname: string): Promise<string[][]> {
const recordType = 'TXT'
const cached = this._TXTcache.get(utils.getCacheKey(hostname, recordType))
return this.resolveAny({
hostname,
recordType: 'TXT',
cache: this._TXTcache
})
}

/**
* Resolves any record type.
*
* @param DNSResolver<T> - DNSResolver object
*/
private async resolveAny ({
hostname,
recordType,
cache
}: DNSResolver<string>): Promise<string[]>
private async resolveAny ({
hostname,
recordType,
cache
}: DNSResolver<string[]>): Promise<string[][]>
private async resolveAny ({
hostname,
recordType,
cache = this._cache
}: DNSResolver<string | string[]>): Promise<Array<string | string[]>> {
const cached = cache.get(utils.getCacheKey(hostname, recordType))
if (cached != null) {
return cached
}
Expand All @@ -230,10 +194,10 @@ class Resolver {
recordType
), controller.signal)

const data = response.Answer.map(a => [a.data.replace(/['"]+/g, '')])
const data = response.Answer.map(RECORD_EXTRACTORS[recordType])
const ttl = Math.min(...response.Answer.map(a => a.TTL))

this._TXTcache.set(utils.getCacheKey(hostname, recordType), data, { ttl })
cache.set(utils.getCacheKey(hostname, recordType), data, { ttl })

return data
} catch (err) {
Expand All @@ -248,14 +212,17 @@ class Resolver {
}

if (aborted) {
throw Object.assign(new Error('queryTxt ECANCELLED'), {
throw Object.assign(new Error(`query${recordType} ECANCELLED`), {
code: 'ECANCELLED'
})
}

throw new Error(`Could not resolve ${hostname} record ${recordType}`)
}

/**
* Clears the cache.
*/
clearCache (): void {
this._cache.clear()
this._TXTcache.clear()
Expand Down