Move downloader and socket input parsing to xpc services (#675)

* XPC updater POC

* WIP

* obo

* WIP

* Working

* .

* .

* .

* Cleanup

* Cleanup

* Throw restrict

* Remove dead protocol.

* .

* Fix ECDSA test.

* Scripts

Sources/AgentRequestParser/Info.plist

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>XPCService</key>
+	<dict>
+		<key>ServiceType</key>
+		<string>Application</string>
+	</dict>
+</dict>
+</plist>

Sources/AgentRequestParser/main.swift

@@ -0,0 +1,55 @@
+import XPC
+import SecretAgentKit
+import OSLog
+
+private let logger = Logger(subsystem: "com.maxgoedjen.secretive.secretagent.AgentRequestParser", category: "Parser")
+
+func handleRequest(_ request: XPCListener.IncomingSessionRequest) -> XPCListener.IncomingSessionRequest.Decision {
+    logger.log("Parser received inbound request")
+    return request.accept { xpcMessage in
+        xpcMessage.handoffReply(to: .global(qos: .userInteractive)) {
+            logger.log("Parser accepted inbound request")
+            handle(with: xpcMessage)
+        }
+    }
+}
+
+func handle(with xpcMessage: XPCReceivedMessage) {
+    do {
+        let parser = SSHAgentInputParser()
+        let result = try parser.parse(data: xpcMessage.wrappedDecode())
+        logger.log("Parser parsed message as type \(result.debugDescription)")
+        xpcMessage.reply(result)
+    } catch {
+        logger.error("Parser failed with error \(error)")
+        xpcMessage.reply(error)
+    }
+}
+
+extension XPCReceivedMessage {
+
+    func wrappedDecode() throws(SSHAgentInputParser.AgentParsingError) -> Data {
+        do {
+            return try decode(as: Data.self)
+        } catch {
+            throw SSHAgentInputParser.AgentParsingError.invalidData
+        }
+    }
+
+}
+
+do {
+    if #available(macOS 26.0, *) {
+        _ = try XPCListener(
+            service: "com.maxgoedjen.Secretive.AgentRequestParser",
+            requirement: .isFromSameTeam(),
+            incomingSessionHandler: handleRequest(_:)
+        )
+    } else {
+        _ = try XPCListener(service: "com.maxgoedjen.Secretive.AgentRequestParser", incomingSessionHandler: handleRequest(_:))
+    }
+    logger.log("Parser initialized")
+    dispatchMain()
+} catch {
+    logger.error("Failed to create parser, error: \(error)")
+}