DNSResolver: DNS resolution can now happen synchronously
Signed-off-by: Roopesh Chander <roop@roopc.net>
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4404bb2b7d
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651ffa0c51
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@ -4,6 +4,10 @@
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import Network
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import Foundation
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enum DNSResolverError: Error {
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case dnsResolutionFailed(hostnames: [String])
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}
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class DNSResolver {
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let endpoints: [Endpoint?]
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let dispatchGroup: DispatchGroup
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@ -32,10 +36,11 @@ class DNSResolver {
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return resolvedEndpoints
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}
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func resolve(completionHandler: @escaping ([Endpoint?]?) -> Void) {
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func resolveSync() throws -> [Endpoint?] {
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let endpoints = self.endpoints
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let dispatchGroup = self.dispatchGroup
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dispatchWorkItems = []
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var resolvedEndpoints: [Endpoint?] = Array<Endpoint?>(repeating: nil, count: endpoints.count)
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var isResolvedByDNSRequest: [Bool] = Array<Bool>(repeating: false, count: endpoints.count)
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for (i, endpoint) in self.endpoints.enumerated() {
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@ -54,26 +59,26 @@ class DNSResolver {
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DispatchQueue.global(qos: .userInitiated).async(group: dispatchGroup, execute: workItem)
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}
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}
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dispatchGroup.notify(queue: .main) {
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dispatchGroup.wait() // TODO: Timeout?
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var hostnamesWithDnsResolutionFailure: [String] = []
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assert(endpoints.count == resolvedEndpoints.count)
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for (i, endpoint) in endpoints.enumerated() {
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guard let endpoint = endpoint, let resolvedEndpoint = resolvedEndpoints[i] else {
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completionHandler(nil)
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return
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}
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if (isResolvedByDNSRequest[i]) {
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DNSResolver.cache.setObject(resolvedEndpoint.stringRepresentation() as NSString,
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forKey: endpoint.stringRepresentation() as NSString)
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for tuple in zip(endpoints, resolvedEndpoints) {
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let endpoint = tuple.0
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let resolvedEndpoint = tuple.1
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if let endpoint = endpoint {
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if (resolvedEndpoint == nil) {
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// DNS resolution failed
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guard let hostname = endpoint.hostname() else { fatalError() }
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hostnamesWithDnsResolutionFailure.append(hostname)
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}
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}
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let numberOfEndpointsToResolve = endpoints.compactMap { $0 }.count
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let numberOfResolvedEndpoints = resolvedEndpoints.compactMap { $0 }.count
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if (numberOfResolvedEndpoints < numberOfEndpointsToResolve) {
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completionHandler(nil)
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} else {
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completionHandler(resolvedEndpoints)
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}
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if (!hostnamesWithDnsResolutionFailure.isEmpty) {
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throw DNSResolverError.dnsResolutionFailed(hostnames: hostnamesWithDnsResolutionFailure)
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}
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return resolvedEndpoints
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}
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func cancel() {
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