Translate NWError into easier to use structs

Added NWTLSError, NWDNSError and NWPOSIXError to wrap Network.framework errors. The reason to do this was to make it easier to read Errors thrown from the Network.framework.

Author: adam-fowler

Sources/AsyncHTTPClient/ConnectionPool.swift

@@ -397,6 +397,13 @@ final class ConnectionPool {
                 channel.pipeline.addSSLHandlerIfNeeded(for: self.key, tlsConfiguration: self.configuration.tlsConfiguration, addSSLClient: requiresSSLHandler, handshakePromise: handshakePromise)
                 return handshakePromise.futureResult.flatMap {
                    channel.pipeline.addHTTPClientHandlers(leftOverBytesStrategy: .forwardBytes)
+                }.flatMap {
+                    #if canImport(Network)
+                    if #available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *), bootstrap.underlyingBootstrap is NIOTSConnectionBootstrap {
+                        return channel.pipeline.addHandler(NWErrorHandler(), position: .first)
+                    }
+                    #endif
+                    return eventLoop.makeSucceededFuture(())
                 }.map {
                    let connection = Connection(key: self.key, channel: channel, parentPool: self.parentPool)
                    connection.isLeased = true
@@ -406,6 +413,12 @@ final class ConnectionPool {
                 self.configureCloseCallback(of: connection)
                 return connection
             }.flatMapError { error in
+                var error = error
+                #if canImport(Network)
+                if #available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *), bootstrap.underlyingBootstrap is NIOTSConnectionBootstrap {
+                    error = NWErrorHandler.translateError(error)
+                }
+                #endif
                 // This promise may not have been completed if we reach this
                 // so we fail it to avoid any leak
                 handshakePromise.fail(error)

Sources/AsyncHTTPClient/NIOTransportServices/ErrorHandler.swift

@@ -0,0 +1,115 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the AsyncHTTPClient open source project
+//
+// Copyright (c) 2018-2020 Apple Inc. and the AsyncHTTPClient project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of AsyncHTTPClient project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+#if canImport(Network)
+
+import Network
+import NIO
+import NIOHTTP1
+import NIOTransportServices
+
+public struct NWDNSError: Error {
+    
+    /// DNS error type. Error type list is defined in <dns_sd.h>
+    public let errorType: DNSServiceErrorType
+    
+    /// actual reason, in human readable form
+    private let reason: String
+    
+    /// Initialise a NWDNSError
+    /// - Parameters:
+    ///   - errorType: DNS error type
+    ///   - reason: String describing reason for error
+    public init(_ errorType: DNSServiceErrorType, reason: String) {
+        self.errorType = errorType
+        self.reason = reason
+    }
+}
+
+extension NWDNSError: CustomStringConvertible {
+    public var description: String { return reason }
+}
+
+public struct NWPOSIXError: Error {
+    
+    /// POSIX error code (enum)
+    public let errorCode: POSIXErrorCode
+    
+    /// actual reason, in human readable form
+    private let reason: String
+    
+    /// Initialise a NWPOSIXError
+    /// - Parameters:
+    ///   - errorType: posix error type
+    ///   - reason: String describing reason for error
+    public init(_ errorCode: POSIXErrorCode, reason: String) {
+        self.errorCode = errorCode
+        self.reason = reason
+    }
+}
+
+extension NWPOSIXError: CustomStringConvertible {
+    public var description: String { return reason }
+}
+
+public struct NWTLSError: Error {
+
+    /// TLS error status. List of TLS errors can be found in <Security/SecureTransport.h>
+    public let status: OSStatus
+    
+    /// actual reason, in human readable form
+    private let reason: String
+
+    /// initialise a NWTLSError
+    /// - Parameters:
+    ///   - status: TLS status
+    ///   - reason: String describing reason for error
+    public init(_ status: OSStatus, reason: String) {
+        self.status = status
+        self.reason = reason
+    }
+}
+
+extension NWTLSError: CustomStringConvertible {
+    public var description: String { return reason }
+}
+
+@available (macOS 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *)
+class NWErrorHandler: ChannelInboundHandler {
+    typealias InboundIn = HTTPClientResponsePart
+    
+    func errorCaught(context: ChannelHandlerContext, error: Error) {
+        context.fireErrorCaught(NWErrorHandler.translateError(error))
+    }
+    
+    static func translateError(_ error: Error) -> Error {
+        
+        if let error = error as? NWError {
+            switch error {
+            case .dns(let errorType):
+                return NWDNSError(errorType, reason: error.localizedDescription)
+            case .tls(let status):
+                return NWTLSError(status, reason: error.localizedDescription)
+            case .posix(let errorCode):
+                return NWPOSIXError(errorCode, reason: error.localizedDescription)
+            default:
+                return error
+            }
+        }
+        return error
+    }
+}
+
+
+#endif

Tests/AsyncHTTPClientTests/HTTPClientTests.swift

@@ -538,7 +538,7 @@ class HTTPClientTests: XCTestCase {
         }
 
         XCTAssertThrowsError(try httpClient.get(url: "https://localhost:\(httpBin.port)/noresponse").wait(), "Should fail") { error in
-            guard case let error = error as? NIOSSLError, error == .uncleanShutdown else {
+            guard case let sslError = error as? NIOSSLError, sslError == .uncleanShutdown else {
                 return XCTFail("Should fail with NIOSSLError.uncleanShutdown")
             }
         }
@@ -555,7 +555,7 @@ class HTTPClientTests: XCTestCase {
         }
 
         XCTAssertThrowsError(try httpClient.get(url: "https://localhost:\(httpBin.port)/noresponse").wait(), "Should fail") { error in
-            guard case let error = error as? NIOSSLError, error == .uncleanShutdown else {
+            guard case let sslError = error as? NIOSSLError, sslError == .uncleanShutdown else {
                 return XCTFail("Should fail with NIOSSLError.uncleanShutdown")
             }
         }
@@ -572,7 +572,7 @@ class HTTPClientTests: XCTestCase {
         }
 
         XCTAssertThrowsError(try httpClient.get(url: "https://localhost:\(httpBin.port)/wrongcontentlength").wait(), "Should fail") { error in
-            guard case let error = error as? NIOSSLError, error == .uncleanShutdown else {
+            guard case let sslError = error as? NIOSSLError, sslError == .uncleanShutdown else {
                 return XCTFail("Should fail with NIOSSLError.uncleanShutdown")
             }
         }
@@ -1017,21 +1017,19 @@ class HTTPClientTests: XCTestCase {
                 XCTFail("Shouldn't succeed")
                 continue
             case .failure(let error):
-                #if canImport(Network)
                 if isTestingNIOTS() {
-                    if #available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *) {
-                        guard let clientError = error as? NWError, case NWError.tls(let status) = clientError else {
-                            XCTFail("Unexpected error: \(error)")
-                            continue
-                        }
-                        XCTAssertEqual(status, errSSLHandshakeFail)
+                    #if canImport(Network)
+                    guard let clientError = error as? NWTLSError else {
+                        XCTFail("Unexpected error: \(error)")
+                        continue
+                    }
+                    XCTAssertEqual(clientError.status, errSSLHandshakeFail)
+                    #endif
+                } else {
+                    guard let clientError = error as? NIOSSLError, case NIOSSLError.handshakeFailed = clientError else {
+                        XCTFail("Unexpected error: \(error)")
+                        continue
                     }
-                    continue
-                }
-                #endif
-                guard let clientError = error as? NIOSSLError, case NIOSSLError.handshakeFailed = clientError else {
-                    XCTFail("Unexpected error: \(error)")
-                    continue
                 }
             }
         }
@@ -1675,15 +1673,13 @@ class HTTPClientTests: XCTestCase {
         }
 
         XCTAssertThrowsError(try httpClient.get(url: "http://localhost:\(port)").wait()) { error in
-            #if canImport(Network)
-            if #available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *), isTestingNIOTS() {
-                guard let nwError = error as? NWError, case NWError.posix(let posixErrorCode) = nwError, posixErrorCode == .ECONNREFUSED else {
+            if isTestingNIOTS() {
+                guard let ioError = error as? IOError, ioError.errnoCode == ECONNREFUSED else {
                     XCTFail("Unexpected error: \(error)")
                     return
                 }
                 return
             }
-            #endif
             guard error is NIOConnectionError else {
                 XCTFail("Unexpected error: \(error)")
                 return
@@ -1710,7 +1706,7 @@ class HTTPClientTests: XCTestCase {
             XCTAssertNoThrow(try httpClient.syncShutdown())
         }
         #if canImport(Network)
-        if #available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *) {
+        if #available(macOS 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *) {
             XCTAssertTrue(httpClient.eventLoopGroup is NIOTSEventLoopGroup)
             return
         }