Added: ability to set basic authentication on requests (#778)

Motivation:

As an HTTP library, async-http-client should have authentication
support.

Modifications:

This adds a `setBasicAuth()` method to both HTTPClientRequest and
`HTTPClient.Request` and their related unit tests.

Result:

Library users will be able to leverage this method to use basic
authentication on their requests without implementing this in their own
projects.

Note: I also ran the tests (`swift test`) with the
`docker.io/library/swift:6.0-focal` and
`docker.io/library/swift:5.10.1-focal` to ensure linux compatibility.

Signed-off-by: Agam Dua <agam_dua@apple.com>

Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest+auth.swift

@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the AsyncHTTPClient open source project
+//
+// Copyright (c) 2024 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
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+extension HTTPClientRequest {
+    /// Set basic auth for a request.
+    ///
+    /// - parameters:
+    ///     - username: the username to authenticate with
+    ///     - password: authentication password associated with the username
+    public mutating func setBasicAuth(username: String, password: String) {
+        self.headers.setBasicAuth(username: username, password: password)
+    }
+}

Sources/AsyncHTTPClient/BasicAuth.swift

@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the AsyncHTTPClient open source project
+//
+// Copyright (c) 2024 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
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+import NIOHTTP1
+
+/// Generates base64 encoded username + password for http basic auth.
+///
+/// - Parameters:
+///   - username: the username to authenticate with
+///   - password: authentication password associated with the username
+/// - Returns: encoded credentials to use the Authorization: Basic http header.
+func encodeBasicAuthCredentials(username: String, password: String) -> String {
+    var value = Data()
+    value.reserveCapacity(username.utf8.count + password.utf8.count + 1)
+    value.append(contentsOf: username.utf8)
+    value.append(UInt8(ascii: ":"))
+    value.append(contentsOf: password.utf8)
+    return value.base64EncodedString()
+}
+
+extension HTTPHeaders {
+    /// Sets the basic auth header
+    mutating func setBasicAuth(username: String, password: String) {
+        let encoded = encodeBasicAuthCredentials(username: username, password: password)
+        self.replaceOrAdd(name: "Authorization", value: "Basic \(encoded)")
+    }
+}

Sources/AsyncHTTPClient/HTTPHandler.swift

@@ -285,6 +285,15 @@ extension HTTPClient {
 
             return (head, metadata)
         }
+
+        /// Set basic auth for a request.
+        ///
+        /// - parameters:
+        ///     - username: the username to authenticate with
+        ///     - password: authentication password associated with the username
+        public mutating func setBasicAuth(username: String, password: String) {
+            self.headers.setBasicAuth(username: username, password: password)
+        }
     }
 
     /// Represents an HTTP response.

Tests/AsyncHTTPClientTests/HTTPClientRequestTests.swift

@@ -57,6 +57,17 @@ class HTTPClientRequestTests: XCTestCase {
         }
     }
 
+    func testBasicAuth() {
+        XCTAsyncTest {
+            var request = Request(url: "https://example.com/get")
+            request.setBasicAuth(username: "foo", password: "bar")
+            var preparedRequest: PreparedRequest?
+            XCTAssertNoThrow(preparedRequest = try PreparedRequest(request))
+            guard let preparedRequest = preparedRequest else { return }
+            XCTAssertEqual(preparedRequest.head.headers.first(name: "Authorization")!, "Basic Zm9vOmJhcg==")
+        }
+    }
+
     func testUnixScheme() {
         XCTAsyncTest {
             var request = Request(url: "unix://%2Fexample%2Ffolder.sock/some_path")

Tests/AsyncHTTPClientTests/HTTPClientTests.swift

@@ -3668,4 +3668,11 @@ final class HTTPClientTests: XCTestCaseHTTPClientTestsBaseClass {
         let response3 = try await client.execute(request, timeout: /* infinity */ .hours(99))
         XCTAssertEqual(.ok, response3.status)
     }
+
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
+    func testRequestBasicAuth() async throws {
+        var request = try HTTPClient.Request(url: self.defaultHTTPBinURLPrefix)
+        request.setBasicAuth(username: "foo", password: "bar")
+        XCTAssertEqual(request.headers.first(name: "Authorization"), "Basic Zm9vOmJhcg==")
+    }
 }