120 lines
5.0 KiB
Swift
120 lines
5.0 KiB
Swift
// SPDX-License-Identifier: MIT
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// Copyright © 2018 WireGuard LLC. All rights reserved.
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import Network
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import Foundation
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class DNSResolver {
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let endpoints: [Endpoint?]
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let dispatchGroup: DispatchGroup
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var dispatchWorkItems: [DispatchWorkItem]
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init(endpoints: [Endpoint?]) {
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self.endpoints = endpoints
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self.dispatchWorkItems = []
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self.dispatchGroup = DispatchGroup()
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}
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func resolve(completionHandler: @escaping ([Endpoint?]?) -> Void) {
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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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let numberOfEndpointsToResolve = endpoints.compactMap { $0 }.count
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for (i, endpoint) in self.endpoints.enumerated() {
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guard let endpoint = endpoint else { return }
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let workItem = DispatchWorkItem {
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resolvedEndpoints[i] = DNSResolver.resolveSync(endpoint: endpoint)
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}
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dispatchWorkItems.append(workItem)
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DispatchQueue.global(qos: .userInitiated).async(group: dispatchGroup, execute: workItem)
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}
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dispatchGroup.notify(queue: .main) {
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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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}
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}
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func cancel() {
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for workItem in dispatchWorkItems {
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workItem.cancel()
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}
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}
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deinit {
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cancel()
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}
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}
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extension DNSResolver {
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// Based on DNS resolution code by Jason Donenfeld <jason@zx2c4.com>
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// in parse_endpoint() in src/tools/config.c in the WireGuard codebase
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private static func resolveSync(endpoint: Endpoint) -> Endpoint? {
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var hints = addrinfo(
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ai_flags: 0,
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ai_family: AF_UNSPEC,
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ai_socktype: SOCK_DGRAM, // WireGuard is UDP-only
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ai_protocol: IPPROTO_UDP, // WireGuard is UDP-only
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ai_addrlen: 0,
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ai_canonname: nil,
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ai_addr: nil,
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ai_next: nil)
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var resultPointer = UnsafeMutablePointer<addrinfo>(OpaquePointer(bitPattern: 0))
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switch (endpoint.host) {
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case .name(let name, _):
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// The endpoint is a hostname and needs DNS resolution
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let returnValue = getaddrinfo(
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name.cString(using: .utf8), // Hostname
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"\(endpoint.port)".cString(using: .utf8), // Port
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&hints,
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&resultPointer)
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if (returnValue == 0) {
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// getaddrinfo succeeded
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let ipv4Buffer = UnsafeMutablePointer<Int8>.allocate(capacity: Int(INET_ADDRSTRLEN))
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let ipv6Buffer = UnsafeMutablePointer<Int8>.allocate(capacity: Int(INET6_ADDRSTRLEN))
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var ipv4AddressString: String? = nil
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var ipv6AddressString: String? = nil
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while (resultPointer != nil) {
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let result = resultPointer!.pointee
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resultPointer = result.ai_next
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if (result.ai_family == AF_INET && result.ai_addrlen == INET_ADDRSTRLEN) {
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if (inet_ntop(result.ai_family, result.ai_addr, ipv4Buffer, result.ai_addrlen) != nil) {
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ipv4AddressString = String(cString: ipv4Buffer)
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// If we found an IPv4 address, we can stop
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break
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}
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} else if (result.ai_family == AF_INET6 && result.ai_addrlen == INET6_ADDRSTRLEN) {
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if (ipv6AddressString != nil) {
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// If we already have an IPv6 address, we can skip this one
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continue
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}
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if (inet_ntop(result.ai_family, result.ai_addr, ipv6Buffer, result.ai_addrlen) != nil) {
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ipv6AddressString = String(cString: ipv6Buffer)
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}
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}
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}
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ipv4Buffer.deallocate()
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ipv6Buffer.deallocate()
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// We prefer an IPv4 address over an IPv6 address
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if let ipv4AddressString = ipv4AddressString, let ipv4Address = IPv4Address(ipv4AddressString) {
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return Endpoint(host: NWEndpoint.Host.ipv4(ipv4Address), port: endpoint.port)
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} else if let ipv6AddressString = ipv6AddressString, let ipv6Address = IPv6Address(ipv6AddressString) {
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return Endpoint(host: NWEndpoint.Host.ipv6(ipv6Address), port: endpoint.port)
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} else {
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return nil
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}
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} else {
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// getaddrinfo failed
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return nil
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}
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default:
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// The endpoint is already resolved
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return endpoint
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}
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}
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}
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