Support switching to different "modes" using vendor specific control messages.

Use USBMUXD_DEFAULT_DEVICE_MODE env. var. to let the user control desired mode.

2 files changed, 113 insertions, 8 deletions

diff --git a/src/usb.c b/src/usb.c
index 4ff2d07..ca941bc 100644
--- a/src/usb.c
+++ b/src/usb.c
@@ -65,6 +65,15 @@ struct usb_device {
         struct libusb_device_descriptor devdesc;
 };
 
+struct mode_user_data {
+        uint8_t bus, address;
+        uint8_t bRequest;
+        uint16_t wValue;
+        uint16_t wIndex;
+        uint16_t wLength;
+        unsigned int timeout;
+};
+
 static struct collection device_list;
 
 static struct timeval next_dev_poll_time;
@@ -357,6 +366,77 @@ static void get_langid_callback(struct libusb_transfer *transfer)
         }
 }
 
+static int submit_vendor_specific(struct libusb_device_handle *handle, struct mode_user_data *user_data, libusb_transfer_cb_fn callback) {
+        struct libusb_transfer* ctrl_transfer = libusb_alloc_transfer(0);
+        unsigned char* buffer = malloc(LIBUSB_CONTROL_SETUP_SIZE);
+        uint8_t bRequestType = LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_ENDPOINT_IN | LIBUSB_RECIPIENT_DEVICE;
+        libusb_fill_control_setup(buffer, bRequestType, user_data->bRequest, user_data->wValue, user_data->wIndex, user_data->wLength);
+        
+        ctrl_transfer->flags = LIBUSB_TRANSFER_FREE_BUFFER | LIBUSB_TRANSFER_FREE_TRANSFER;
+        libusb_fill_control_transfer(ctrl_transfer, handle, buffer, callback, user_data, user_data->timeout);
+        
+        return libusb_submit_transfer(ctrl_transfer);
+}
+
+static void switch_mode_cb(struct libusb_transfer* transfer) {
+        struct mode_user_data* user_data = transfer->user_data;
+
+        if(transfer->status != LIBUSB_TRANSFER_COMPLETED) {
+                usbmuxd_log(LL_ERROR, "Failed to request mode switch for device %i-%i (%i)", user_data->bus, user_data->address, transfer->status);
+                free(transfer->user_data);
+                return;
+        }
+
+        unsigned char *data = libusb_control_transfer_get_data(transfer);
+
+        usbmuxd_log(LL_INFO, "Received response %i for switch mode %i for device %i-%i", data[0], user_data->wIndex, user_data->bus, user_data->address);
+        free(transfer->user_data);
+}
+
+static void get_mode_cb(struct libusb_transfer* transfer) {
+        struct mode_user_data* user_data = transfer->user_data;
+        int res;
+
+        if(transfer->status != LIBUSB_TRANSFER_COMPLETED) {
+                usbmuxd_log(LL_ERROR, "Failed to request get mode for device %i-%i (%i)", user_data->bus, user_data->address, transfer->status);
+                free(transfer->user_data);
+                return;
+        }
+
+        unsigned char *data = libusb_control_transfer_get_data(transfer);
+
+        char* desired_mode = getenv(ENV_DEVICE_MODE);
+        if (!desired_mode) {
+                user_data->wIndex = 0x1;
+        }
+        else if (!strncmp(desired_mode, "2", 1)) {
+                user_data->wIndex = 0x2;
+        } 
+        else if (!strncmp(desired_mode, "3", 1)) {
+                user_data->wIndex = 0x3;
+        }
+        // Response is 3:3:3 for initial mode, 5:3:3 otherwise.
+        // In later commit, should infer the mode from available configurations and interfaces. 
+        usbmuxd_log(LL_INFO, "Received response %i:%i:%i for get_mode request for device %i-%i", data[0], data[1], data[2], user_data->bus, user_data->address);
+        if (user_data->wIndex > 1 && data[0] == 3 && data[1] == 3 && data[2] == 3) {
+                // 3:3:3 means the initial mode
+                usbmuxd_log(LL_WARNING, "Switching device %i-%i mode to %i", user_data->bus, user_data->address, user_data->wIndex);
+                
+                user_data->bRequest = APPLE_VEND_SPECIFIC_SET_MODE;
+                user_data->wValue = 0;
+                user_data->wLength = 1;
+
+                if ((res = submit_vendor_specific(transfer->dev_handle, user_data, switch_mode_cb)) != 0) {
+                        usbmuxd_log(LL_WARNING, "Could not request to switch mode %i for device %i-%i (%i)", user_data->wIndex, user_data->bus, user_data->address, res);
+                }
+        } 
+        else {
+                // in other modes, usually 5:3:3
+                usbmuxd_log(LL_WARNING, "Skipping switch device %i-%i mode", user_data->bus, user_data->address);
+                free(transfer->user_data);
+        }
+}
+
 static int usb_device_add(libusb_device* dev)
 {
         int j, res;
@@ -397,6 +477,25 @@ static int usb_device_add(libusb_device* dev)
                 return -1;
         }
 
+        // On top of configurations, Apple have multiple "modes" for devices, namely:
+        // 1: An "initial" mode with 4 configurations
+        // 2: "Valeria" mode, where configuration 5 is included with interface for H.265 video capture (activated when recording screen with QuickTime in macOS)
+        // 3: "CDC NCM" mode, where configuration 5 is included with interface for Ethernet/USB (activated using internet-sharing feature in macOS)
+        // Request current mode asynchroniously, so it can be changed in callback if needed
+        usbmuxd_log(LL_INFO, "Requesting current mode from device %i-%i", bus, address);
+        struct mode_user_data* user_data = malloc(sizeof(struct mode_user_data));
+        user_data->bus = bus;
+        user_data->address = address;
+        user_data->bRequest = APPLE_VEND_SPECIFIC_GET_MODE;
+        user_data->wValue = 0;
+        user_data->wIndex = 0;
+        user_data->wLength = 4;
+        user_data->timeout = 1000;
+
+        if (submit_vendor_specific(handle, user_data, get_mode_cb) != 0) {
+                usbmuxd_log(LL_WARNING, "Could not request current mode from device %d-%d", bus, address);
+        }
+        // Potentially, the rest of this function can be factored out and called from get_mode_callback/switch_mode_callback (where desired mode is known)
         int desired_config = devdesc.bNumConfigurations;
         if (desired_config > 4) {
                 if (desired_config > 5) {
@@ -412,14 +511,16 @@ static int usb_device_add(libusb_device* dev)
                                 desired_config = 4;
                                 break;
                         }
-                        if (config->bNumInterfaces != 3) {
-                                usbmuxd_log(LL_WARNING, "Device %d-%d: Ignoring possibly bad configuration 5, choosing configuration 4 instead.", bus, address);
-                                desired_config = 4;
-                                break;
-                        }
-                        intf = &config->interface[2].altsetting[0];
-                        if (intf->bInterfaceClass != 0xFF || intf->bInterfaceSubClass != 0x2A || intf->bInterfaceProtocol != 0xFF) {
-                                usbmuxd_log(LL_WARNING, "Device %d-%d: Ignoring possibly bad configuration 5, choosing configuration 4 instead.", bus, address);
+                        // In Valeria mode, there are 3 interfaces and usbmuxd is at 2
+                        // In CDC NCM mode, there are 4 interfaces and usbmuxd is at 1
+                        // Otherwize, 0 is expected to be of a different class.
+                        int usbmux_intf_index = config->bNumInterfaces == 3 ? 2 : config->bNumInterfaces == 4 ? 1 : 0;
+                        intf = &config->interface[usbmux_intf_index].altsetting[0];
+                        if (
+                                        intf->bInterfaceClass != INTERFACE_CLASS || 
+                                        intf->bInterfaceSubClass != INTERFACE_SUBCLASS || 
+                                        intf->bInterfaceProtocol != INTERFACE_PROTOCOL) {
+                                usbmuxd_log(LL_WARNING, "Device %d-%d: can't find usbmux interface in configuration 5, choosing configuration 4 instead.", bus, address);
                                 desired_config = 4;
                                 break;
                         }
diff --git a/src/usb.h b/src/usb.h
index b1b9bb9..4e44cce 100644
--- a/src/usb.h
+++ b/src/usb.h
@@ -50,6 +50,10 @@
 #define PID_APPLE_SILICON_RESTORE_LOW 0x1901
 #define PID_APPLE_SILICON_RESTORE_MAX 0x1905
 
+#define ENV_DEVICE_MODE "USBMUXD_DEFAULT_DEVICE_MODE"
+#define APPLE_VEND_SPECIFIC_GET_MODE 0x45
+#define APPLE_VEND_SPECIFIC_SET_MODE 0x52
+
 struct usb_device;
 
 int usb_init(void);