Class: Uhid

Inherits:
Object
  • Object
show all
Defined in:
lib/uhid.rb

Overview

Linux UHID class.

This class allows the creation of virtual USB HID devices on Linux using the ‘uhid` kernel module.

Author:

  • David P. Sugar (r4gus)

Constant Summary collapse

RD_FIDO =

FIDO2/U2F USB report descriptor

"\x06\xd0\xf1\x09\x01\xa1\x01\x09"\
"\x20\x15\x00\x26\xff\x00\x75\x08"\
"\x95\x40\x81\x02\x09\x21\x15\x00"\
"\x26\xff\x00\x75\x08\x95\x40\x91"\
"\x02\xc0".force_encoding("BINARY")

Instance Method Summary collapse

Constructor Details

#initialize(name = "ruby-fido", rd = RD_FIDO, vendor = 0x15d9, product = 0x0a37, path = "/dev/uhid") ⇒ Uhid

Create a new virtual HID device.

Parameters:

  • name (String) (defaults to: "ruby-fido") —

    the name of the device.

  • rd (String) (defaults to: RD_FIDO) —

    ‘BINARY` encoded report descriptor.

  • vendor (Integer) (defaults to: 0x15d9) —

    vendor ID.

  • product (Integer) (defaults to: 0x0a37) —

    product ID.

  • path (String) (defaults to: "/dev/uhid") —

    the file path (usually ‘/dev/uhid`).



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# File 'lib/uhid.rb', line 22

def initialize(
  name = "ruby-fido", 
  rd = RD_FIDO, 
  vendor = 0x15d9, 
  product = 0x0a37, 
  path = "/dev/uhid"
)
  @file = File.open(path, "r+", File::NONBLOCK)
  ObjectSpace.define_finalizer(self, method(:finalize))
  self.create(name, vendor, product, rd)
end

Instance Method Details

#read ⇒ Object

Read data from the host.

All returned hashes contain the type key that specifies the type of the received packet. Valid types are: START, STOP, OPEN, CLOSE, OUTPUT. Only OUTPUT Hashes contain a data field that holds the data received by the host.



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# File 'ext/uhid/uhid.c', line 123

static VALUE
cuhid_read_data(VALUE self)
{
    ID file_var = rb_intern("@file");
    VALUE file = rb_ivar_get(self, file_var);
    Check_Type(file, T_FILE);
    VALUE file_fileno = rb_funcall(file, rb_intern("fileno"), 0);
    int fd = NUM2INT(file_fileno);

    struct uhid_event ev; 
    
    memset(&ev, 0, sizeof(ev));
    ssize_t ret = read(fd, &ev, sizeof(ev));

    if (ret == -1) { // EAGAIN
        return Qnil;
    }
    
    VALUE h = rb_hash_new();
    switch (ev.type) {
    case UHID_START:
        rb_hash_aset(h, rb_str_new_cstr("type"), rb_str_new_cstr("START"));
        return h;
    case UHID_STOP:
        rb_hash_aset(h, rb_str_new_cstr("type"), rb_str_new_cstr("STOP"));
        return h;
    case UHID_OPEN:
        rb_hash_aset(h, rb_str_new_cstr("type"), rb_str_new_cstr("OPEN"));
        return h;
    case UHID_CLOSE:
        rb_hash_aset(h, rb_str_new_cstr("type"), rb_str_new_cstr("CLOSE"));
        return h;
    case UHID_OUTPUT:
        rb_hash_aset(h, rb_str_new_cstr("type"), rb_str_new_cstr("OUTPUT"));
        rb_hash_aset(h, rb_str_new_cstr("data"), rb_str_new((const char *) ev.u.output.data, ev.u.output.size));
        return h;
    default:
        return Qnil;
    }
}

#write(data) ⇒ Object

Write the given data to the host.

Make sure you send the data in a format, expected by the host, e.g. in 64 byte chunks.

Parameters:

  • data (String) —

    the data to be sent to the host.



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# File 'ext/uhid/uhid.c', line 84

static VALUE
cuhid_write_data(VALUE self, VALUE data)
{
    const char* d = RSTRING_PTR(StringValue(data));
    size_t l = RSTRING_LEN(StringValue(data));
    size_t size = l;
    if (size > UHID_DATA_MAX) {
        size = UHID_DATA_MAX;
    }

    struct uhid_event ev; 
    
    memset(&ev, 0, sizeof(ev));
    ev.type = UHID_INPUT2;
    memcpy(ev.u.input2.data, d, size);
    ev.u.input2.size = size;

    ID file_var = rb_intern("@file");
    VALUE file = rb_ivar_get(self, file_var);
    Check_Type(file, T_FILE);
    VALUE file_fileno = rb_funcall(file, rb_intern("fileno"), 0);
    int fd = NUM2INT(file_fileno);

    cuhid_write(fd, &ev);
    
    // We the number of processed bytes
    return INT2NUM(size);
}