c - libusb 数据输出

Question

我试图通过使用输出数据libusb_interrupt_transfer，函数返回0，但是，我看不到来自 Wireshark 的任何数据传输输出（在 USB 嗅探模式下），并且设备没有响应应该输出的数据。返回值是否0表示数据是从usb口发出来的？如果是这样，我是否libusb_interrupt_transfer在我的代码上使用了错误的函数？

这是我的代码（我在 ubuntu 12.10 - Linux ubuntu 3.5.0-21-generic #32-Ubuntu SMP Tue Dec 11 18:52:46 UTC 2012 i686 i686 i686 GNU/Linux 上运行代码）

#include <stdio.h> //printf, etc.
#include <sys/types.h>
#include <unistd.h>
#include <libusb.h> //libusb functions
#include <inttypes.h> //unit16t
#include <unistd.h> //sleep function
#include <stdlib.h> //exit()

const uint16_t VENDOR = 6069; /* = 0x17b5 */
const uint16_t PRODUCT = 32;  /* = 0x0020 */
const int CONFIGURATION_VALUE = 1;


int msgsend(unsigned char data[64]) {
    libusb_device **devs; //pointer to pointer of device, used to retrieve a list of devices
    libusb_context *ctx = NULL; //a libusb session

    int r; //for return values
    ssize_t cnt; //holding number of devices in list

    r = libusb_init(&ctx); //initialize a library session
    if (r < 0){
        exit(1);}
    libusb_set_debug(ctx, 3);//set verbosity level to 3

    cnt = libusb_get_device_list(ctx, &devs);
    if (cnt < 0)
        return (int) cnt;


    libusb_device_handle *handle;
    handle = libusb_open_device_with_vid_pid(ctx, VENDOR, PRODUCT);

    if (handle==NULL) {
        fprintf(stderr, "No logging system found.\n");
        libusb_free_device_list(devs, 1);
        libusb_exit(NULL);
        exit(1);
    }
    libusb_device *device = libusb_get_device(handle);

    struct libusb_config_descriptor *config = NULL;
    int err = libusb_get_config_descriptor_by_value(device, CONFIGURATION_VALUE, &config);

    if (err != LIBUSB_SUCCESS){
        printf("libusb_get_config_descriptor_by_value error\n");
        exit(1);
    }
    if(config->bNumInterfaces == 1){
        if(config->interface[0].num_altsetting ==1){
            if(config->interface[0].altsetting[0].bNumEndpoints == 2) {

                libusb_free_config_descriptor(config);

                err = libusb_kernel_driver_active(handle, 0);
                if (err >= LIBUSB_SUCCESS) {
                    if (err == 1) {
                        printf("Kernel driver is active, trying to detach\n");
                        err = libusb_detach_kernel_driver(handle, 0);
                        if (err != LIBUSB_SUCCESS) {
                                printf("Error detaching interface from kernel: libusb_error_string(err)\n");
                        }
                    }

                    err = libusb_set_configuration(handle, CONFIGURATION_VALUE);
                    if (err == LIBUSB_SUCCESS) {
                        err = libusb_claim_interface(handle, 0);
                        if (err == LIBUSB_SUCCESS) {
                            err = libusb_set_interface_alt_setting(handle, 0, 0);
                            if (err == LIBUSB_SUCCESS) {

                                unsigned char ENDPOINT_OUTPUT = 0x02;
                                unsigned char ENDPOINT_INPUT = 0x81;
                                int actual_length;
                                int return_value = 0;

                                return_value = libusb_interrupt_transfer(handle, ENDPOINT_OUTPUT, data, sizeof(data), &actual_length, 0);

                                if (return_value == 0){
                                        printf("msg was sent successfully! return_value=%d\n",return_value);
                                    }else {
                                        printf("return_value=%d, something went wrong",return_value);
                                        perror( "libusb_submit_transfer\n" );
                                    }

                                }
                            }else{
                                    printf("cannot claim the interface\n");
                                    exit(1);
                                }

                           }
                        }
                    }

                }
            }
    libusb_free_device_list(devs, 1); //free the list, unref the devices in it

    r = libusb_release_interface(handle, 0);
    libusb_close(handle); //close the device we opened
    libusb_exit(ctx);//needs to be called to end the


    return 0;
}



int main(){
     unsigned char data[64]={0x12, 0x01,0x00,0x03,0x00,0x00,0xFF,0x05,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,


     unsigned char data2[64]={0x12, 0x02,0x00,0x03,0x00,0x00,0xFF,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

     unsigned int seqnum = 0x01;

     while(1){
         data[1] = seqnum;
         printf("max light is set\n");
         msgsend(data);
         if(seqnum == 0xff){
             seqnum = 0;
         }else{
             seqnum++;
         }
         sleep(2);

         data2[1] = seqnum;
         printf("min light is set\n");
         msgsend(data2);
         if(seqnum == 0xff){
             seqnum = 0;
         }else{
             seqnum++;
         }
         sleep(2);
     }

    return 0;
}