Add host lookup xpc service (#826)

* Add host lookup xpc service

* Remove restriction that snuck in

* Test fixes

Sources/SecretAgent/XPCHostsfileReader.swift

@@ -0,0 +1,36 @@
+import Foundation
+import OSLog
+import XPCWrappers
+import OSLog
+
+public final class XPCHostsfileReader {
+
+    private let logger = Logger(subsystem: "com.maxgoedjen.secretive.secretagent", category: "XPCHostsfileReader")
+    private let session: XPCTypedSession<[Data: String], HostsfileReaderError>
+
+    public init() async throws {
+        logger.debug("Creating XPCHostsfileReader")
+        session = try await XPCTypedSession(serviceName: "com.maxgoedjen.Secretive.SecretAgentHostsfileReader", warmup: true)
+        logger.debug("XPCHostsfileReader is warmed up.")
+    }
+
+    public func read() async throws -> [Data: String] {
+        logger.debug("Reading hosts file")
+        defer { logger.debug("Read hosts file") }
+        return try await session.send(Data())
+    }
+
+    deinit {
+        session.complete()
+    }
+
+}
+
+extension XPCHostsfileReader {
+
+    public enum HostsfileReaderError: Error, Codable {
+        case fileDoesNotExist
+        case parseError
+    }
+
+}