diff --git a/src/libusb_util.c b/src/libusb_util.c
new file mode 100644
index 0000000..cb435e2
--- /dev/null
+++ b/src/libusb_util.c
@@ -0,0 +1,297 @@
+/* libisb utilities
+ * 
+ * (C) 2010-2016 by Harald Welte <hwelte@hmw-consulting.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#include <errno.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <libusb.h>
+
+#include "libusb_util.h"
+
+static char path_buf[USB_MAX_PATH_LEN];
+
+static char *get_path(libusb_device *dev)
+{
+#if (defined(LIBUSB_API_VERSION) && LIBUSB_API_VERSION >= 0x01000102) || (defined(LIBUSBX_API_VERSION) && LIBUSBX_API_VERSION >= 0x01000102)
+	uint8_t path[8];
+	int r,j;
+	r = libusb_get_port_numbers(dev, path, sizeof(path));
+	if (r > 0) {
+		sprintf(path_buf,"%d-%d",libusb_get_bus_number(dev),path[0]);
+		for (j = 1; j < r; j++){
+			sprintf(path_buf+strlen(path_buf),".%d",path[j]);
+		};
+	}
+	return path_buf;
+#else
+# warning "libusb too old - building without USB path support!"
+	return NULL;
+#endif
+}
+
+static int match_dev_id(const struct libusb_device_descriptor *desc, const struct dev_id *id)
+{
+	if ((desc->idVendor == id->vendor_id) && (desc->idProduct == id->product_id))
+		return 1;
+	return 0;
+}
+
+
+static int match_dev_ids(const struct libusb_device_descriptor *desc, const struct dev_id *ids)
+{
+	const struct dev_id *id;
+
+	for (id = ids; id->vendor_id || id->product_id; id++) {
+		if (match_dev_id(desc, id))
+			return 1;
+	}
+	return 0;
+}
+
+libusb_device **find_matching_usb_devs(const struct dev_id *dev_ids)
+{
+	libusb_device **list;
+	libusb_device **out = calloc(256, sizeof(libusb_device *));
+	libusb_device **cur = out;
+	unsigned int i;
+	int rc;
+
+	if (!out)
+		return NULL;
+
+	rc = libusb_get_device_list(NULL, &list);
+	if (rc <= 0) {
+		perror("No USB devices found");
+		free(out);
+		return NULL;
+	}
+
+	for (i = 0; list[i] != NULL; i++) {
+		struct libusb_device_descriptor dev_desc;
+		libusb_device *dev = list[i];
+
+		rc = libusb_get_device_descriptor(dev, &dev_desc);
+		if (rc < 0) {
+			perror("Couldn't get device descriptor\n");
+			libusb_unref_device(dev);
+			continue;
+		}
+
+		if (match_dev_ids(&dev_desc, dev_ids)) {
+			*cur = dev;
+			cur++;
+			/* FIXME: overflow check */
+		} else
+			libusb_unref_device(dev);
+	}
+	if (cur == out) {
+		libusb_free_device_list(list, 1);
+		free(out);
+		return NULL;
+	}
+
+	libusb_free_device_list(list, 0);
+	return out;
+}
+
+int dev_find_matching_interfaces(libusb_device *dev, int class, int sub_class, int protocol,
+				 struct usb_interface_match *out, unsigned int out_len)
+{
+	struct libusb_device_descriptor dev_desc;
+	int rc, i, out_idx = 0;
+	uint8_t addr;
+	char *path;
+
+	rc = libusb_get_device_descriptor(dev, &dev_desc);
+	if (rc < 0) {
+		perror("Couldn't get device descriptor\n");
+		return -EIO;
+	}
+
+	addr = libusb_get_device_address(dev);
+	path = get_path(dev);
+
+	/* iterate over all configurations */
+	for (i = 0; i < dev_desc.bNumConfigurations; i++) {
+		struct libusb_config_descriptor *conf_desc;
+		int j;
+
+		rc = libusb_get_config_descriptor(dev, i, &conf_desc);
+		if (rc < 0) {
+			fprintf(stderr, "Couldn't get config descriptor %u\n", i);
+			continue;
+		}
+		/* iterate over all interfaces */
+		for (j = 0; j < conf_desc->bNumInterfaces; j++) {
+			const struct libusb_interface *intf = &conf_desc->interface[j];
+			int k;
+			/* iterate over all alternate settings */
+			for (k = 0; k < intf->num_altsetting; k++) {
+				const struct libusb_interface_descriptor *if_desc;
+				if_desc = &intf->altsetting[k];
+				if (class >= 0 && if_desc->bInterfaceClass != class)
+					continue;
+				if (sub_class >= 0 && if_desc->bInterfaceSubClass != sub_class)
+					continue;
+				if (protocol >= 0 && if_desc->bInterfaceProtocol != protocol)
+					continue;
+				/* MATCH! */
+				out[out_idx].usb_dev = dev;
+				out[out_idx].vendor = dev_desc.idVendor;
+				out[out_idx].product = dev_desc.idProduct;
+				out[out_idx].addr = addr;
+				strncpy(out[out_idx].path, path, sizeof(out[out_idx].path));
+				out[out_idx].path[sizeof(out[out_idx].path)-1] = '\0';
+				out[out_idx].configuration = conf_desc->bConfigurationValue;
+				out[out_idx].interface = if_desc->bInterfaceNumber;
+				out[out_idx].altsetting = if_desc->bAlternateSetting;
+				out[out_idx].class = if_desc->bInterfaceClass;
+				out[out_idx].sub_class = if_desc->bInterfaceSubClass;
+				out[out_idx].protocol = if_desc->bInterfaceProtocol;
+				out[out_idx].string_idx = if_desc->iInterface;
+				out_idx++;
+				if (out_idx >= out_len)
+					return out_idx;
+			}
+		}
+	}
+	return out_idx;
+}
+
+int usb_match_interfaces(libusb_context *ctx, const struct dev_id *dev_ids,
+			 int class, int sub_class, int protocol,
+			 struct usb_interface_match *out, unsigned int out_len)
+{
+	struct usb_interface_match *out_cur = out;
+	unsigned int out_len_remain = out_len;
+	libusb_device **list;
+	libusb_device **dev;
+
+	list = find_matching_usb_devs(dev_ids);
+	if (!list)
+		return 0;
+
+	for (dev = list; *dev; dev++) {
+		int rc;
+
+#if 0
+		struct libusb_device_descriptor dev_desc;
+		uint8_t ports[8];
+		uint8_t addr;
+		rc = libusb_get_device_descriptor(*dev, &dev_desc);
+		if (rc < 0) {
+			perror("Cannot get device descriptor");
+			continue;
+		}
+
+		addr = libusb_get_device_address(*dev);
+
+		rc = libusb_get_port_numbers(*dev, ports, sizeof(ports));
+		if (rc < 0) {
+			perror("Cannot get device path");
+			continue;
+		}
+
+		printf("Found USB Device %04x:%04x at address %d\n",
+			dev_desc.idVendor, dev_desc.idProduct, addr);
+#endif
+
+		rc = dev_find_matching_interfaces(*dev, class, sub_class, protocol, out_cur, out_len_remain);
+		if (rc < 0)
+			continue;
+		out_cur += rc;
+		out_len_remain -= rc;
+
+	}
+	return out_len - out_len_remain;
+}
+
+libusb_device_handle *usb_open_claim_interface(libusb_context *ctx,
+					       const struct usb_interface_match *ifm)
+{
+	int rc, config;
+	struct dev_id dev_ids[] = { { ifm->vendor, ifm->product }, { 0, 0 } };
+	libusb_device **list;
+	libusb_device **dev;
+	libusb_device_handle *usb_devh = NULL;
+
+	list = find_matching_usb_devs(dev_ids);
+	if (!list) {
+		perror("No USB device with matching VID/PID");
+		return NULL;
+	}
+
+	for (dev = list; *dev; dev++) {
+		int addr;
+		char *path;
+
+		addr = libusb_get_device_address(*dev);
+		path = get_path(*dev);
+		if ((ifm->addr && addr == ifm->addr) ||
+		    (strlen(ifm->path) && !strcmp(path, ifm->path))) {
+			rc = libusb_open(*dev, &usb_devh);
+			if (rc < 0) {
+				fprintf(stderr, "Cannot open device: %s\n", libusb_error_name(rc));
+				usb_devh = NULL;
+				break;
+			}
+			rc = libusb_get_configuration(usb_devh, &config);
+			if (rc < 0) {
+				fprintf(stderr, "Cannot get current configuration: %s\n", libusb_error_name(rc));
+				libusb_close(usb_devh);
+				usb_devh = NULL;
+				break;
+			}
+			if (config != ifm->configuration) {
+				rc = libusb_set_configuration(usb_devh, ifm->configuration);
+				if (rc < 0) {
+					fprintf(stderr, "Cannot set configuration: %s\n", libusb_error_name(rc));
+					libusb_close(usb_devh);
+					usb_devh = NULL;
+					break;
+				}
+			}
+			rc = libusb_claim_interface(usb_devh, ifm->interface);
+			if (rc < 0) {
+				fprintf(stderr, "Cannot claim interface: %s\n", libusb_error_name(rc));
+				libusb_close(usb_devh);
+				usb_devh = NULL;
+				break;
+			}
+			rc = libusb_set_interface_alt_setting(usb_devh, ifm->interface, ifm->altsetting);
+			if (rc < 0) {
+				fprintf(stderr, "Cannot set interface altsetting: %s\n", libusb_error_name(rc));
+				libusb_release_interface(usb_devh, ifm->interface);
+				libusb_close(usb_devh);
+				usb_devh = NULL;
+				break;
+			}
+		}
+	}
+
+	/* unref / free list */
+	for (dev = list; *dev; dev++)
+		libusb_unref_device(*dev);
+	free(list);
+
+	return usb_devh;
+}