tart run: introduce --net-bridged (#245)

* tart run: introduce --net-bridged

* tart.entitlements: add com.apple.vm.networking

Resources/tart.entitlements

@@ -4,5 +4,7 @@
 <dict>
 	<key>com.apple.security.virtualization</key>
 	<true/>
+	<key>com.apple.vm.networking</key>
+	<true/>
 </dict>
-</plist>
+</plist>

Sources/tart/Commands/Run.swift

@@ -54,10 +54,21 @@ struct Run: AsyncParsableCommand {
                                               """, valueName: "name:path[:ro]"))
   var dir: [String] = []
 
+  @Option(help: ArgumentHelp("""
+                             Use bridged networking instead of the default shared (NAT) networking \n(e.g. --net-bridged=en0 or --net-bridged=\"Wi-Fi\")
+                             """, discussion: """
+                                              Specify "list" as an interface name (--net-bridged=list) to list the available bridged interfaces.
+                                              """, valueName: "interface name"))
+  var netBridged: String?
+
   func validate() throws {
     if vnc && vncExperimental {
       throw ValidationError("--vnc and --vnc-experimental are mutually exclusive")
     }
+
+    if withSoftnet && netBridged != nil {
+      throw ValidationError("--with-softnet and --net-bridged are mutually exclusive")
+    }
   }
 
   @MainActor
@@ -65,7 +76,7 @@ struct Run: AsyncParsableCommand {
     let vmDir = try VMStorageLocal().open(name)
     vm = try VM(
       vmDir: vmDir,
-      withSoftnet: withSoftnet,
+      network: userSpecifiedNetwork(vmDir: vmDir) ?? NetworkShared(),
       additionalDiskAttachments: additionalDiskAttachments(),
       directoryShares: directoryShares()
     )
@@ -125,6 +136,47 @@ struct Run: AsyncParsableCommand {
     }
   }
 
+  func userSpecifiedNetwork(vmDir: VMDirectory) throws -> Network? {
+    if withSoftnet {
+      let config = try VMConfig.init(fromURL: vmDir.configURL)
+
+      return try Softnet(vmMACAddress: config.macAddress.string)
+    }
+
+    if let netBridged = netBridged {
+      let matchingInterfaces = VZBridgedNetworkInterface.networkInterfaces.filter { interface in
+        interface.identifier == netBridged || interface.localizedDisplayName == netBridged
+      }
+
+      if matchingInterfaces.isEmpty {
+        let available = bridgeInterfaces().joined(separator: ", ")
+        throw ValidationError("no bridge interfaces matched \"\(netBridged)\", "
+          + "available interfaces: \(available)")
+      }
+
+      if matchingInterfaces.count > 1 {
+        throw ValidationError("more than one bridge interface matched \"\(netBridged)\", "
+          + "consider refining the search criteria")
+      }
+
+      return NetworkBridged(interface: matchingInterfaces.first!)
+    }
+
+    return nil
+  }
+
+  func bridgeInterfaces() -> [String] {
+    VZBridgedNetworkInterface.networkInterfaces.map { interface in
+      var bridgeDescription = interface.identifier
+
+      if let localizedDisplayName = interface.localizedDisplayName {
+        bridgeDescription += " (or \"\(localizedDisplayName)\")"
+      }
+
+      return bridgeDescription
+    }
+  }
+
   func additionalDiskAttachments() throws -> [VZDiskImageStorageDeviceAttachment] {
     var result: [VZDiskImageStorageDeviceAttachment] = []
     let readOnlySuffix = ":ro"

Sources/tart/Network/Network.swift

@@ -0,0 +1,7 @@
+import Virtualization
+
+protocol Network {
+  func attachment() -> VZNetworkDeviceAttachment
+  func run() throws
+  func stop() throws
+}

Sources/tart/Network/NetworkBridged.swift

@@ -0,0 +1,22 @@
+import Foundation
+import Virtualization
+
+class NetworkBridged: Network {
+    let interface: VZBridgedNetworkInterface
+
+    init(interface: VZBridgedNetworkInterface) {
+        self.interface = interface
+    }
+
+    func attachment() -> VZNetworkDeviceAttachment {
+        VZBridgedNetworkDeviceAttachment(interface: interface)
+    }
+
+    func run() throws {
+        // no-op, only used for Softnet
+    }
+
+    func stop() throws {
+        // no-op, only used for Softnet
+    }
+}

Sources/tart/Network/NetworkShared.swift

@@ -0,0 +1,16 @@
+import Foundation
+import Virtualization
+
+class NetworkShared: Network {
+    func attachment() -> VZNetworkDeviceAttachment {
+        VZNATNetworkDeviceAttachment()
+    }
+
+    func run() throws {
+        // no-op, only used for Softnet
+    }
+
+    func stop() throws {
+        // no-op, only used for Softnet
+    }
+}

Sources/tart/Network/Softnet.swift

@@ -1,10 +1,11 @@
 import Foundation
+import Virtualization
 
 enum SoftnetError: Error {
   case InitializationFailed(why: String)
 }
 
-class Softnet {
+class Softnet: Network {
   private let process = Process()
 
   let vmFD: Int32
@@ -57,4 +58,9 @@ class Softnet {
       throw SoftnetError.InitializationFailed(why: "setsockopt(SO_SNDBUF) returned \(ret)")
     }
   }
+
+  func attachment() -> VZNetworkDeviceAttachment {
+    let fh = FileHandle.init(fileDescriptor: vmFD)
+    return VZFileHandleNetworkDeviceAttachment(fileHandle: fh)
+  }
 }

Sources/tart/VM.swift

@@ -34,10 +34,10 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
   // VM's config
   var config: VMConfig
 
-  var softnet: Softnet? = nil
+  var network: Network
 
   init(vmDir: VMDirectory,
-       withSoftnet: Bool = false,
+       network: Network = NetworkShared(),
        additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment] = [],
        directoryShares: [DirectoryShare] = []
   ) throws {
@@ -49,13 +49,10 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     }
 
     // Initialize the virtual machine and its configuration
-    if withSoftnet {
-      softnet = try Softnet(vmMACAddress: config.macAddress.string)
-    }
-
+    self.network = network
     let configuration = try Self.craftConfiguration(diskURL: vmDir.diskURL,
       nvramURL: vmDir.nvramURL, vmConfig: config,
-      softnet: softnet, additionalDiskAttachments: additionalDiskAttachments,
+      network: network, additionalDiskAttachments: additionalDiskAttachments,
             directoryShares: directoryShares)
     virtualMachine = VZVirtualMachine(configuration: configuration)
 
@@ -114,7 +111,7 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     vmDir: VMDirectory,
     ipswURL: URL?,
     diskSizeGB: UInt16,
-    withSoftnet: Bool = false,
+    network: Network = NetworkShared(),
     additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment] = []
   ) async throws {
     let ipswURL = ipswURL != nil ? ipswURL! : try await VM.retrieveLatestIPSW();
@@ -149,12 +146,9 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     try config.save(toURL: vmDir.configURL)
 
     // Initialize the virtual machine and its configuration
-    if withSoftnet {
-      softnet = try Softnet(vmMACAddress: config.macAddress.string)
-    }
-
+    self.network = network
     let configuration = try Self.craftConfiguration(diskURL: vmDir.diskURL, nvramURL: vmDir.nvramURL,
-      vmConfig: config, softnet: softnet,
+      vmConfig: config, network: network,
       additionalDiskAttachments: additionalDiskAttachments,
       directoryShares: [])
     virtualMachine = VZVirtualMachine(configuration: configuration)
@@ -193,9 +187,7 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
   }
 
   func run(_ recovery: Bool) async throws {
-    if let softnet = softnet {
-      try softnet.run()
-    }
+    try network.run()
 
     DispatchQueue.main.sync {
       Task {
@@ -225,16 +217,14 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
       }
     }
 
-    if let softnet = softnet {
-      try softnet.stop();
-    }
+    try network.stop()
   }
 
   static func craftConfiguration(
     diskURL: URL,
     nvramURL: URL,
     vmConfig: VMConfig,
-    softnet: Softnet? = nil,
+    network: Network = NetworkShared(),
     additionalDiskAttachments: [VZDiskImageStorageDeviceAttachment],
     directoryShares: [DirectoryShare]
   ) throws -> VZVirtualMachineConfiguration {
@@ -268,13 +258,7 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
 
     // Networking
     let vio = VZVirtioNetworkDeviceConfiguration()
-
-    if let softnet = softnet {
-      let fh = FileHandle.init(fileDescriptor: softnet.vmFD)
-      vio.attachment = VZFileHandleNetworkDeviceAttachment(fileHandle: fh)
-    } else {
-      vio.attachment = VZNATNetworkDeviceAttachment()
-    }
+    vio.attachment = network.attachment()
     vio.macAddress = vmConfig.macAddress
     configuration.networkDevices = [vio]