usb.c

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