introduce api function to read usb string descriptors

This API allows to read manufacturer and product names as well as the
serial number advertized by the device on the bus.

3 files changed, 123 insertions, 4 deletions

diff --git a/include/rtl-sdr.h b/include/rtl-sdr.h
index a5b3dfd..804334d 100644
--- a/include/rtl-sdr.h
+++ b/include/rtl-sdr.h
@@ -33,6 +33,22 @@ RTLSDR_API uint32_t rtlsdr_get_device_count(void);
 
 RTLSDR_API const char* rtlsdr_get_device_name(uint32_t index);
 
+/*!
+ * Get USB device strings.
+ *
+ * NOTE: The string arguments must provide space for up to 256 bytes.
+ *
+ * \param index the device index
+ * \param manufact manufacturer name, may be NULL
+ * \param product product name, may be NULL
+ * \param serial serial number, may be NULL
+ * \return 0 on success
+ */
+RTLSDR_API int rtlsdr_get_device_usb_strings(uint32_t index,
+					     char *manufact,
+					     char *product,
+					     char *serial);
+
 RTLSDR_API int rtlsdr_open(rtlsdr_dev_t **dev, uint32_t index);
 
 RTLSDR_API int rtlsdr_close(rtlsdr_dev_t *dev);
@@ -69,6 +85,20 @@ RTLSDR_API int rtlsdr_set_xtal_freq(rtlsdr_dev_t *dev, uint32_t rtl_freq,
 RTLSDR_API int rtlsdr_get_xtal_freq(rtlsdr_dev_t *dev, uint32_t *rtl_freq,
 				    uint32_t *tuner_freq);
 
+/*!
+ * Get USB device strings.
+ *
+ * NOTE: The string arguments must provide space for up to 256 bytes.
+ *
+ * \param dev the device handle given by rtlsdr_open()
+ * \param manufact manufacturer name, may be NULL
+ * \param product product name, may be NULL
+ * \param serial serial number, may be NULL
+ * \return 0 on success
+ */
+RTLSDR_API int rtlsdr_get_usb_strings(rtlsdr_dev_t *dev, char *manufact,
+				      char *product, char *serial);
+
 RTLSDR_API int rtlsdr_set_center_freq(rtlsdr_dev_t *dev, uint32_t freq);
 
 /*!
diff --git a/src/librtlsdr.c b/src/librtlsdr.c
index 7721c4a..d961985 100644
--- a/src/librtlsdr.c
+++ b/src/librtlsdr.c
@@ -571,6 +571,47 @@ int rtlsdr_get_xtal_freq(rtlsdr_dev_t *dev, uint32_t *rtl_freq, uint32_t *tuner_
 	return 0;
 }
 
+int rtlsdr_get_usb_strings(rtlsdr_dev_t *dev, char *manufact, char *product,
+			    char *serial)
+{
+	struct libusb_device_descriptor dd;
+	libusb_device *device = NULL;
+	const int buf_max = 256;
+	int r = 0;
+
+	if (!dev || !dev->devh)
+		return -1;
+
+	device = libusb_get_device(dev->devh);
+
+	r = libusb_get_device_descriptor(device, &dd);
+	if (r < 0)
+		return -1;
+
+	if (manufact) {
+		memset(manufact, 0, buf_max);
+		libusb_get_string_descriptor_ascii(dev->devh, dd.iManufacturer,
+						   (unsigned char *)manufact,
+						   buf_max);
+	}
+
+	if (product) {
+		memset(product, 0, buf_max);
+		libusb_get_string_descriptor_ascii(dev->devh, dd.iProduct,
+						   (unsigned char *)product,
+						   buf_max);
+	}
+
+	if (serial) {
+		memset(serial, 0, buf_max);
+		libusb_get_string_descriptor_ascii(dev->devh, dd.iSerialNumber,
+						   (unsigned char *)serial,
+						   buf_max);
+	}
+
+	return 0;
+}
+
 int rtlsdr_set_center_freq(rtlsdr_dev_t *dev, uint32_t freq)
 {
 	int r = -1;
@@ -815,6 +856,52 @@ const char *rtlsdr_get_device_name(uint32_t index)
 		return "";
 }
 
+int rtlsdr_get_device_usb_strings(uint32_t index, char *manufact,
+				   char *product, char *serial)
+{
+	int r = -2;
+	int i;
+	libusb_context *ctx;
+	libusb_device **list;
+	struct libusb_device_descriptor dd;
+	rtlsdr_dongle_t *device = NULL;
+	rtlsdr_dev_t devt;
+	uint32_t device_count = 0;
+	ssize_t cnt;
+
+	libusb_init(&ctx);
+
+	cnt = libusb_get_device_list(ctx, &list);
+
+	for (i = 0; i < cnt; i++) {
+		libusb_get_device_descriptor(list[i], &dd);
+
+		device = find_known_device(dd.idVendor, dd.idProduct);
+
+		if (device) {
+			device_count++;
+
+			if (index == device_count - 1) {
+				r = libusb_open(list[i], &devt.devh);
+				if (!r) {
+					r = rtlsdr_get_usb_strings(&devt,
+								   manufact,
+								   product,
+								   serial);
+					libusb_close(devt.devh);
+				}
+				break;
+			}
+		}
+	}
+
+	libusb_free_device_list(list, 1);
+
+	libusb_exit(ctx);
+
+	return r;
+}
+
 int rtlsdr_open(rtlsdr_dev_t **out_dev, uint32_t index)
 {
 	int r;
diff --git a/src/rtl_sdr.c b/src/rtl_sdr.c
index 98d5fc5..45995c2 100644
--- a/src/rtl_sdr.c
+++ b/src/rtl_sdr.c
@@ -107,6 +107,7 @@ int main(int argc, char **argv)
 	uint32_t samp_rate = DEFAULT_SAMPLE_RATE;
 	uint32_t out_block_size = DEFAULT_BUF_LENGTH;
 	int device_count;
+	char vendor[256], product[256], serial[256];
 #ifndef _WIN32
 	while ((opt = getopt(argc, argv, "d:f:g:s:b:S::")) != -1) {
 		switch (opt) {
@@ -168,13 +169,14 @@ int main(int argc, char **argv)
 	}
 
 	fprintf(stderr, "Found %d device(s):\n", device_count);
-	for (i = 0; i < device_count; i++)
-		fprintf(stderr, "  %d:  %s\n", i, rtlsdr_get_device_name(i));
+	for (i = 0; i < device_count; i++) {
+		rtlsdr_get_device_usb_strings(i, vendor, product, serial);
+		fprintf(stderr, "  %d:  %s, %s, SN: %s\n", i, vendor, product, serial);
+	}
 	fprintf(stderr, "\n");
 
 	fprintf(stderr, "Using device %d: %s\n",
-		dev_index,
-		rtlsdr_get_device_name(dev_index));
+		dev_index, rtlsdr_get_device_name(dev_index));
 
 	r = rtlsdr_open(&dev, dev_index);
 	if (r < 0) {