OSX IOKit driver for implementing virtual HID devices from userspace
Install https://github.com/unbit/foohid/releases/download/0.1/foohid.pkg and reboot your system.
The kext will expose a IOUserClient allowing you to create and manage virtual HID devices.
Use the official python2 wrapper (available at https://github.com/unbit/foohid-py) to start playing with virtual hid devices:
pip install foohid(will install the foohid extension).
Now clone the foohid-py repository
git clone https://github.com/unbit/foohid-pywhere 3 tests are available:
test_mouse.py will create a virtual mouse. Just run it, and every second your mouse pointer will move to a random position
test_joypad.py will create a virtual joypad. Just run it, and every second lext and right axis will be updated.
test_list.py will show the listing feature (a bunch of virtual devices will be created, listed and destroyed)
Note: python3 support should be ready soon
4 Methods are exposed:
- create (selector 0)
- destroy (selector 1)
- send (selector 2)
- list (selector 3)
takes 4 input arguments (name pointer, name length, reportdescriptor pointer, reportdescriptor length) and 1 output argument (64bit integer set to 0 on success).
It creates a new fake/virtual HID device with the specified reportdescriptor
takes 2 input arguments (name pointer, name length) and 1 output argument (64bit integer set to 0 on success).
It cancels a previously created fake/virtual HID device
takes 4 input arguments (name pointer, name length, msg pointer, msg length) and 1 output argument (64bit integer set to 0 on success).
It generates a HID event from a previously created fake/virtual HID device
takes 2 input arguments (buffer pointer, buffer length) and 2 output arguments (needed bytes and returned items)
It returns (into the supplied buffer pointer) the list of available fake/virtual devices separated by \0. The items output value contains the number of returned items. If the supplied buffer is not big enough, the needed bytes value contains a suggestion for a second run
Building report descriptors is a really annoying task.
To simplify testing, the following one is a generic mouse (thanks http://eleccelerator.com/tutorial-about-usb-hid-report-descriptors/)
unsigned char report_descriptor[] = {
0x05, 0x01, // USAGE_PAGE (Generic Desktop)
0x09, 0x02, // USAGE (Mouse)
0xa1, 0x01, // COLLECTION (Application)
0x09, 0x01, // USAGE (Pointer)
0xa1, 0x00, // COLLECTION (Physical)
0x05, 0x09, // USAGE_PAGE (Button)
0x19, 0x01, // USAGE_MINIMUM (Button 1)
0x29, 0x03, // USAGE_MAXIMUM (Button 3)
0x15, 0x00, // LOGICAL_MINIMUM (0)
0x25, 0x01, // LOGICAL_MAXIMUM (1)
0x95, 0x03, // REPORT_COUNT (3)
0x75, 0x01, // REPORT_SIZE (1)
0x81, 0x02, // INPUT (Data,Var,Abs)
0x95, 0x01, // REPORT_COUNT (1)
0x75, 0x05, // REPORT_SIZE (5)
0x81, 0x03, // INPUT (Cnst,Var,Abs)
0x05, 0x01, // USAGE_PAGE (Generic Desktop)
0x09, 0x30, // USAGE (X)
0x09, 0x31, // USAGE (Y)
0x15, 0x81, // LOGICAL_MINIMUM (-127)
0x25, 0x7f, // LOGICAL_MAXIMUM (127)
0x75, 0x08, // REPORT_SIZE (8)
0x95, 0x02, // REPORT_COUNT (2)
0x81, 0x06, // INPUT (Data,Var,Rel)
0xc0, // END_COLLECTION
0xc0 // END_COLLECTION
}that maps to this c structure
struct mouse_report_t {
uint8_t buttons;
int8_t x;
int8_t y;
}So to create and move a virtual mouse:
#include <IOKit/IOKitLib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define FOOHID_CREATE 0
int main() {
io_iterator_t iterator;
io_service_t service;
// get a reference to the IOService
kern_return_t ret = IOServiceGetMatchingServices(kIOMasterPortDefault, IOServiceMatching("it_unbit_foohid"), &iterator);
if (ret != KERN_SUCCESS) {
printf("unable to access IOService\n");
exit(1);
}
io_connect_t connect;
int found = 0;
// Iterate till success
while ((service = IOIteratorNext(iterator)) != IO_OBJECT_NULL) {
ret = IOServiceOpen(service, mach_task_self(), 0, &connect);
if (ret = KERN_SUCCESS) {
found = 1;
break;
}
}
IOObjectRelease(iterator);
if (!found) {
printf("unable to open IOService\n");
exit(1);
}
uint32_t output_count = 1;
uint64_t output = 0;
// fill input args
uint64_t input[4];
input[0] = (uint64_t) strdup("Virtual GamePad FooBar");
input[1] = strlen( (char *)input[0]);
input[2] = (uint64_t) report_descriptor;
input[3] = sizeof(report_descriptor);
ret = IOConnectCallScalarMethod(connect, FOOHID_CREATE, input, 4, &output, &output_count);
if (ret != KERN_SUCCESS) {
printf("unable to create HID device\n");
exit(1);
}
// update input args to pass hid message
struct mouse_report_t mouse;
input[2] = (uint64_t) &mouse;
input[3] = sizeof(struct mouse_report_t);
for(;;) {
mouse.buttons = 0;
mouse.x = rand();
mouse.y = rand();
// ignore return value, just for testing
IOConnectCallScalarMethod(connect, 2, input, 4, &output, &output_count);
}
}