tart create: support fetching URLs specified in the --from-ipsw option (#256)

* tart create: support fetching URLs specified in the --from-ipsw option

* Use x-amz-meta-digest-sha256 header to cache IPSWs

Sources/tart/Commands/Create.swift

@@ -9,7 +9,7 @@ struct Create: AsyncParsableCommand {
   @Argument(help: "VM name")
   var name: String
 
-  @Option(help: ArgumentHelp("create a macOS VM using path to the IPSW file (or \"latest\") to fetch the latest appropriate IPSW", valueName: "path"))
+  @Option(help: ArgumentHelp("create a macOS VM using path to the IPSW file or URL (or \"latest\", to fetch the latest supported IPSW automatically)", valueName: "path"))
   var fromIPSW: String?
 
   @Flag(help: "create a Linux VM")
@@ -34,11 +34,17 @@ struct Create: AsyncParsableCommand {
 
       try await withTaskCancellationHandler(operation: {
         if let fromIPSW = fromIPSW {
+          let ipswURL: URL
+
           if fromIPSW == "latest" {
-            _ = try await VM(vmDir: tmpVMDir, ipswURL: nil, diskSizeGB: diskSize)
+            ipswURL = try await VM.latestIPSWURL()
+          } else if fromIPSW.starts(with: "http://") || fromIPSW.starts(with: "https://") {
+            ipswURL = URL(string: fromIPSW)!
           } else {
-            _ = try await VM(vmDir: tmpVMDir, ipswURL: URL(fileURLWithPath: fromIPSW), diskSizeGB: diskSize)
+            ipswURL = URL(fileURLWithPath: fromIPSW)
           }
+
+          _ = try await VM(vmDir: tmpVMDir, ipswURL: ipswURL, diskSizeGB: diskSize)
         }
 
         if linux {

Sources/tart/IPSWCache.swift

@@ -9,8 +9,8 @@ class IPSWCache: PrunableStorage {
     try FileManager.default.createDirectory(at: baseURL, withIntermediateDirectories: true)
   }
 
-  func locationFor(image: VZMacOSRestoreImage) -> URL {
-    baseURL.appendingPathComponent("\(image.buildVersion).ipsw", isDirectory: false)
+  func locationFor(fileName: String) -> URL {
+    baseURL.appendingPathComponent(fileName, isDirectory: false)
   }
 
   func prunables() throws -> [Prunable] {

Sources/tart/VM.swift

@@ -60,26 +60,29 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     virtualMachine.delegate = self
   }
 
-  static func retrieveLatestIPSW() async throws -> URL {
-    defaultLogger.appendNewLine("Looking up the latest supported IPSW...")
-    let image = try await withCheckedThrowingContinuation { continuation in
-      VZMacOSRestoreImage.fetchLatestSupported() { result in
-        continuation.resume(with: result)
+  static func retrieveIPSW(remoteURL: URL) async throws -> URL {
+    // Check if we already have this IPSW in cache
+    var request = URLRequest(url: remoteURL)
+    request.httpMethod = "HEAD"
+    let (_, response) = try await URLSession.shared.data(for: request)
+    let httpURLResponse = response as! HTTPURLResponse
+
+    if let hash = httpURLResponse.value(forHTTPHeaderField: "x-amz-meta-digest-sha256") {
+      let ipswLocation = try IPSWCache().locationFor(fileName: "sha256:\(hash).ipsw")
+
+      if FileManager.default.fileExists(atPath: ipswLocation.path) {
+        defaultLogger.appendNewLine("Using cached *.ipsw file...")
+        try ipswLocation.updateAccessDate()
+
+        return ipswLocation
       }
     }
 
-    let expectedIPSWLocation = try IPSWCache().locationFor(image: image)
-
-    if FileManager.default.fileExists(atPath: expectedIPSWLocation.path) {
-      defaultLogger.appendNewLine("Using cached *.ipsw file...")
-      try expectedIPSWLocation.updateAccessDate()
-      return expectedIPSWLocation
-    }
-
-    defaultLogger.appendNewLine("Fetching \(expectedIPSWLocation.lastPathComponent)...")
+    // Download the IPSW
+    defaultLogger.appendNewLine("Fetching \(remoteURL.lastPathComponent)...")
 
     let data: Data = try await withCheckedThrowingContinuation { continuation in
-      let downloadedTask = URLSession.shared.dataTask(with: image.url) { data, response, error in
+      let downloadedTask = URLSession.shared.dataTask(with: remoteURL) { data, response, error in
         if error != nil {
           continuation.resume(throwing: error!)
           return
@@ -94,10 +97,24 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
       downloadedTask.resume()
     }
 
-    try data.write(to: expectedIPSWLocation, options: [.atomic])
-    return expectedIPSWLocation
+    let ipswLocation = try IPSWCache().locationFor(fileName: Digest.hash(data) + ".ipsw")
+    try data.write(to: ipswLocation, options: [.atomic])
+
+    return ipswLocation
   }
-  
+
+  static func latestIPSWURL() async throws -> URL {
+    defaultLogger.appendNewLine("Looking up the latest supported IPSW...")
+
+    let image = try await withCheckedThrowingContinuation { continuation in
+      VZMacOSRestoreImage.fetchLatestSupported() { result in
+        continuation.resume(with: result)
+      }
+    }
+
+    return image.url
+  }
+
   var inFinalState: Bool {
     get {
       virtualMachine.state == VZVirtualMachine.State.stopped ||
@@ -109,12 +126,16 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
 
   init(
     vmDir: VMDirectory,
-    ipswURL: URL?,
+    ipswURL: URL,
     diskSizeGB: UInt16,
     network: Network = NetworkShared(),
     additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment] = []
   ) async throws {
-    let ipswURL = ipswURL != nil ? ipswURL! : try await VM.retrieveLatestIPSW();
+    var ipswURL = ipswURL
+
+    if !ipswURL.isFileURL {
+      ipswURL = try await VM.retrieveIPSW(remoteURL: ipswURL)
+    }
 
     // Load the restore image and try to get the requirements
     // that match both the image and our platform