Add host lookup xpc service (#826)

* Add host lookup xpc service

* Remove restriction that snuck in

* Test fixes

Sources/SecretAgentHostsfileReader/SecretAgentHostsfileReader.swift

@@ -0,0 +1,25 @@
+import Foundation
+import OSLog
+import XPCWrappers
+import SSHProtocolKit
+
+final class SecretAgentHostsfileReader: NSObject, XPCProtocol {
+
+    private let logger = Logger(subsystem: "com.maxgoedjen.secretive.SecretAgentHostsfileReader", category: "SecretAgentHostsfileReader")
+
+    func process(_ data: Data) async throws -> [Data: String] {
+        logger.log("Parsing hostsfile")
+        var result: [Data: String] = [:]
+        for try await line in URL(filePath: NSHomeDirectory().appending("/.ssh/known_hosts")).lines {
+            let split = line.split(separator: " ").map(String.init)
+            guard split.count == 3 else { continue }
+            guard let decoded = Data(base64Encoded: split[2]) else { continue }
+            let reader = OpenSSHReader(data: decoded)
+            _ = try reader.readNextChunk()
+            let key = try reader.readNextChunk()
+            result[key] = split[0]
+        }
+        return result
+    }
+
+}