Add makeServerConfigurationWithMTLS (#286)

To mirror apple/swift-nio-ssl#545

This allows users to easily create a tls configuration for servers which
want to do mtls, with reloading

Author: hamzahrmalik

Package.swift

@@ -300,7 +300,7 @@ let package = Package(
         .package(url: "https://github.com/apple/swift-atomics.git", from: "1.2.0"),
         .package(url: "https://github.com/apple/swift-algorithms.git", from: "1.2.0"),
         .package(url: "https://github.com/apple/swift-certificates.git", from: "1.10.0"),
-        .package(url: "https://github.com/apple/swift-nio-ssl.git", from: "2.29.3"),
+        .package(url: "https://github.com/apple/swift-nio-ssl.git", from: "2.34.0"),
         .package(url: "https://github.com/apple/swift-asn1.git", from: "1.3.1"),
         .package(url: "https://github.com/swift-server/swift-service-lifecycle.git", from: "2.8.0"),
         .package(url: "https://github.com/apple/swift-async-algorithms.git", from: "1.0.0"),

Sources/NIOCertificateReloading/CertificateReloader.swift

@@ -89,6 +89,43 @@ extension TLSConfiguration {
         return configuration
     }
 
+    /// Create a ``NIOSSL/TLSConfiguration`` for use with server-side contexts that expect to validate a client, with
+    /// certificate reloading enabled. For servers that don't need mTLS, try ``TLSConfiguration/makeServerConfiguration(certificateReloader:)``.
+    /// This configuration is very similar to ``TLSConfiguration/makeServerConfiguration(certificateReloader:)`` but
+    /// adds a `trustRoots` requirement. These roots will be used to validate the certificate presented by the peer. It
+    /// also sets the `certificateVerification` field to `noHostnameVerification`, which enables verification but
+    /// disables any hostname checking, which cannot succeed in a server context.
+    ///
+    /// - Parameters:
+    ///  - certificateReloader: A ``CertificateReloader`` to watch for certificate and key pair updates.
+    ///  - trustRoots: The roots used to validate the client certificate.
+    /// - Returns: A ``NIOSSL/TLSConfiguration`` for use with server-side contexts, that reloads the certificate and key
+    ///   used in its SSL handshake.
+    /// - Throws: This method will throw if an override isn't present. This may happen if a certificate or private key
+    ///   could not be loaded from the given paths.
+    public static func makeServerConfigurationWithMTLS(
+        certificateReloader: some CertificateReloader,
+        trustRoots: NIOSSLTrustRoots
+    ) throws -> Self {
+        let override = certificateReloader.sslContextConfigurationOverride
+
+        guard let certificateChain = override.certificateChain else {
+            throw CertificateReloaderError.missingCertificateChain
+        }
+
+        guard let privateKey = override.privateKey else {
+            throw CertificateReloaderError.missingPrivateKey
+        }
+
+        var configuration = Self.makeServerConfigurationWithMTLS(
+            certificateChain: certificateChain,
+            privateKey: privateKey,
+            trustRoots: trustRoots
+        )
+        configuration.setCertificateReloader(certificateReloader)
+        return configuration
+    }
+
     /// Create a ``NIOSSL/TLSConfiguration`` for use with client-side contexts, with certificate reloading enabled.
     /// - Parameter certificateReloader: A ``CertificateReloader`` to watch for certificate and key pair updates.
     /// - Returns: A ``NIOSSL/TLSConfiguration`` for use with client-side contexts, that reloads the certificate and key

Tests/NIOCertificateReloadingTests/TimedCertificateReloaderTests.swift

@@ -730,6 +730,56 @@ final class TimedCertificateReloaderTests: XCTestCase {
         XCTAssertThrowsError(try TimedCertificateReloader.makeReloaderValidatingSources(configuration: config))
     }
 
+    /// This tests that `makeServerConfigurationWithMTLS(certificateReloader:trustRoots:)` correctly extracts the
+    /// certificate chain and private key from `certificateReloader` and sets those in the returned `TLSConfiguration`
+    /// (along with `trustRoots` and setting `.certificateVerification` to `.noHostnameVerification`)
+    func testCreateServerConfigWithMTLS() async throws {
+        let certificateReloader = try TimedCertificateReloader.makeReloaderValidatingSources(
+            refreshInterval: .seconds(10),
+            certificateSource: .init(
+                location: .memory(provider: {
+                    .init(
+                        try Self.sampleCertChain.map { try $0.serializeAsPEM().pemString }.joined(separator: "\n").utf8
+                    )
+                }),
+                format: .pem
+            ),
+            privateKeySource: .init(
+                location: .memory(provider: { .init(Self.samplePrivateKey1.derRepresentation) }),
+                format: .der
+            )
+        )
+
+        let trustRoots = NIOSSLTrustRoots.certificates(
+            try Self.sampleCertChain.map {
+                try NIOSSLCertificate(bytes: .init($0.serializeAsPEM().pemString.utf8), format: .pem)
+            }
+        )
+
+        let tlsConfiguration = try TLSConfiguration.makeServerConfigurationWithMTLS(
+            certificateReloader: certificateReloader,
+            trustRoots: trustRoots
+        )
+
+        // Check whether the configuration is set up with the same certificate chain, private key, and trust roots
+        // that were used to initialize the reloader
+        XCTAssertEqual(
+            tlsConfiguration.certificateChain,
+            try Self.sampleCertChain.map {
+                .certificate(try NIOSSLCertificate(bytes: $0.serializeAsPEM().derBytes, format: .der))
+            }
+        )
+        XCTAssertEqual(
+            tlsConfiguration.privateKey,
+            NIOSSLPrivateKeySource.privateKey(
+                try NIOSSLPrivateKey(bytes: .init(Self.samplePrivateKey1.derRepresentation), format: .der)
+            )
+        )
+        XCTAssertEqual(tlsConfiguration.trustRoots, trustRoots)
+
+        XCTAssertEqual(tlsConfiguration.certificateVerification, .noHostnameVerification)
+    }
+
     static let startDate = Date()
     static let samplePrivateKey1 = P384.Signing.PrivateKey()
     static let samplePrivateKey2 = P384.Signing.PrivateKey()