usb.c

   1
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include <errno.h>
   6 #include <usb.h>
   7 #include <libusb.h>
   8
   9 static int did_usb_init = 0;
  10
  11
  12 static int  usb_get_string_ascii(usb_dev_handle *dev, int index, int langid, char *buf, int buflen)
  13 {
  14         char    buffer[256];
  15         int     rval, i;
  16
  17         if((rval = usb_control_msg(dev,
  18                                    USB_ENDPOINT_IN,
  19                                    USB_REQ_GET_DESCRIPTOR,
  20                                    (USB_DT_STRING << 8) + index,
  21                                    langid, buffer, sizeof(buffer),
  22                                    1000)) < 0)
  23                 return rval;
  24         if(buffer[1] != USB_DT_STRING)
  25                 return 0;
  26         if((unsigned char)buffer[0] < rval)
  27                 rval = (unsigned char)buffer[0];
  28         rval /= 2;
  29         /* lossy conversion to ISO Latin1 */
  30         for(i=1; i<rval; i++) {
  31                 if(i > buflen)  /* destination buffer overflow */
  32                         break;
  33                 buf[i-1] = buffer[2 * i];
  34                 if(buffer[2 * i + 1] != 0)  /* outside of ISO Latin1 range */
  35                         buf[i-1] = '?';
  36         }
  37         buf[i-1] = 0;
  38         return i-1;
  39 }
  40
  41
  42 int usb_match_string(usb_dev_handle *handle, int index, char* string)
  43 {
  44         char tmp[256];
  45         if (string == NULL)
  46                 return 1; /* NULL matches anything */
  47         usb_get_string_ascii(handle, index, 0x409, tmp, 256);
  48         return (strcmp(string,tmp)==0);
  49 }
  50
  51 usb_dev_handle *usb_check_device(struct usb_device *dev,
  52                                  char *vendor_name,
  53                                  char *product_name,
  54                                  char *serial)
  55 {
  56         usb_dev_handle      *handle = usb_open(dev);
  57         if(!handle) {
  58                 fprintf(stderr, "Warning: cannot open USB device: %s\n", usb_strerror());
  59                 return NULL;
  60         }
  61         if (
  62                 usb_match_string(handle, dev->descriptor.iManufacturer, vendor_name) &&
  63                 usb_match_string(handle, dev->descriptor.iProduct,      product_name) &&
  64                 usb_match_string(handle, dev->descriptor.iSerialNumber, serial)
  65                 ) {
  66                 return handle;
  67         }
  68         usb_close(handle);
  69         return NULL;
  70
  71 }
  72
  73 usb_dev_handle *nc_usb_open(int vendor, int product, char *vendor_name, char *product_name, char *serial)
  74 {
  75         struct usb_bus      *bus;
  76         struct usb_device   *dev;
  77         usb_dev_handle      *handle = NULL;
  78
  79         if(!did_usb_init++)
  80                 usb_init();
  81
  82         usb_find_busses();
  83         usb_find_devices();
  84
  85         for(bus=usb_get_busses(); bus; bus=bus->next) {
  86                 for(dev=bus->devices; dev; dev=dev->next) {
  87                                     if(dev->descriptor.idVendor == vendor &&
  88                                        dev->descriptor.idProduct == product) {
  89                                             handle = usb_check_device(dev, vendor_name, product_name, serial);
  90                                             if (handle)
  91                                                     return handle;
  92                                     }
  93                 }
  94         }
  95         return NULL;
  96 }
  97