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DNSResolver: Let's not cache DNS resolution results anymore

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Signed-off-by: Roopesh Chander <roop@roopc.net>
This commit is contained in:
Roopesh Chander
2018-11-08 17:52:11 +05:30
parent 651ffa0c51
commit 8409b7e929
1 changed files with 9 additions and 17 deletions
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WireGuard/WireGuardNetworkExtension/DNSResolver.swift
+9 -17
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@@ -12,7 +12,6 @@ class DNSResolver {
let endpoints: [Endpoint?] let endpoints: [Endpoint?]
let dispatchGroup: DispatchGroup let dispatchGroup: DispatchGroup
var dispatchWorkItems: [DispatchWorkItem] var dispatchWorkItems: [DispatchWorkItem]
static var cache = NSCache<NSString, NSString>()
init(endpoints: [Endpoint?]) { init(endpoints: [Endpoint?]) {
self.endpoints = endpoints self.endpoints = endpoints
@@ -20,20 +19,14 @@ class DNSResolver {
self.dispatchGroup = DispatchGroup() self.dispatchGroup = DispatchGroup()
} }
func resolveWithoutNetworkRequests() -> [Endpoint?]? { func isAllEndpointsAlreadyResolved() -> Bool {
var resolvedEndpoints: [Endpoint?] = Array<Endpoint?>(repeating: nil, count: endpoints.count) for endpoint in self.endpoints {
for (i, endpoint) in self.endpoints.enumerated() {
guard let endpoint = endpoint else { continue } guard let endpoint = endpoint else { continue }
if (endpoint.hasHostAsIPAddress()) { if (!endpoint.hasHostAsIPAddress()) {
resolvedEndpoints[i] = endpoint return false
} else if let resolvedEndpointStringInCache = DNSResolver.cache.object(forKey: endpoint.stringRepresentation() as NSString),
let resolvedEndpointInCache = Endpoint(from: resolvedEndpointStringInCache as String) {
resolvedEndpoints[i] = resolvedEndpointInCache
} else {
return nil
} }
} }
return resolvedEndpoints return true
} }
func resolveSync() throws -> [Endpoint?] { func resolveSync() throws -> [Endpoint?] {
@@ -41,19 +34,18 @@ class DNSResolver {
let dispatchGroup = self.dispatchGroup let dispatchGroup = self.dispatchGroup
dispatchWorkItems = [] dispatchWorkItems = []
if (isAllEndpointsAlreadyResolved()) {
return endpoints
}
var resolvedEndpoints: [Endpoint?] = Array<Endpoint?>(repeating: nil, count: endpoints.count) var resolvedEndpoints: [Endpoint?] = Array<Endpoint?>(repeating: nil, count: endpoints.count)
var isResolvedByDNSRequest: [Bool] = Array<Bool>(repeating: false, count: endpoints.count)
for (i, endpoint) in self.endpoints.enumerated() { for (i, endpoint) in self.endpoints.enumerated() {
guard let endpoint = endpoint else { continue } guard let endpoint = endpoint else { continue }
if (endpoint.hasHostAsIPAddress()) { if (endpoint.hasHostAsIPAddress()) {
resolvedEndpoints[i] = endpoint resolvedEndpoints[i] = endpoint
} else if let resolvedEndpointStringInCache = DNSResolver.cache.object(forKey: endpoint.stringRepresentation() as NSString),
let resolvedEndpointInCache = Endpoint(from: resolvedEndpointStringInCache as String) {
resolvedEndpoints[i] = resolvedEndpointInCache
} else { } else {
let workItem = DispatchWorkItem { let workItem = DispatchWorkItem {
resolvedEndpoints[i] = DNSResolver.resolveSync(endpoint: endpoint) resolvedEndpoints[i] = DNSResolver.resolveSync(endpoint: endpoint)
isResolvedByDNSRequest[i] = true
} }
dispatchWorkItems.append(workItem) dispatchWorkItems.append(workItem)
DispatchQueue.global(qos: .userInitiated).async(group: dispatchGroup, execute: workItem) DispatchQueue.global(qos: .userInitiated).async(group: dispatchGroup, execute: workItem)