feat: use libusb rather than usbdevfs to unclaim kernel driver

feat: read and print responses from barcode scanner
feat: udev rule
docs: add more usage examples

99-honeywell.rules

@@ -0,0 +1,2 @@
+SUBSYSTEM=="usb", ATTRS{idVendor}=="0c2e", ATTRS{idProduct}=="0b07", MODE="0666"
+SUBSYSTEM=="usb", ATTRS{idVendor}=="0c2e", ATTRS{idProduct}=="0b01", MODE="0666"

Makefile

@@ -1,8 +1,8 @@
 
-.PHONY: clean
+.PHONY: honeywell-config clean
 
 honeywell-config:
 	gcc -lusb-1.0 -o honeywell-config honeywell-config.c
 
 clean:
-	rm honeywell-config
+	rm -f honeywell-config

README.md

@@ -7,7 +7,9 @@ A Linux tool for configuring Honeywell barcode scanners via USB.
 ## Why?
 
 I had obtained a used Honeywell Hyperion 1300G scanner, however it was locked down and secured with a password, and the password was unknown.
+
 There is a Windows-only configuration tool from Honeywell called "EZconfig" with which the barcode scanners can be configured via USB, even when locked down.
+
 To not rely on a Windows VM for configuring the scanner, I sniffed the USB traffic using Wireshark and extracted the relevant messages, and wrapped them in this tool.
 
 ## Usage
@@ -20,14 +22,29 @@ The configuration strings need to be provided as command line arguments.  You ca
 ./honeywell-config <string1> [... <stringN>]
 ```
 
+The commands sent to the scanner are prefixed with `>`, the (tokenized) responses from the scanner with `<`.
+
 In general, please refer to your scanner's manual for configuration strings.
 
-Here are some examples.  Please not that this tool most likely needs to run as root.
+Here are some examples.
 
 ### Factory Reset
 
 ```
-./honeywell-config DEFOVR. DEFALT.
+$ ./honeywell-config DEFOVR. DEFALT.
+> DEFOVR.
+< DEFOVR.
+> DEFALT.
+< DEFALT.
+```
+
+### Factory Reset - In one command
+
+```
+$ ./honeywell-config "DEFOVR;DEFALT."
+> DEFOVR;DEFALT.
+< DEFOVR.
+< DEFALT.
 ```
 
 ### Switch Operation Mode
@@ -35,13 +52,17 @@ Here are some examples.  Please not that this tool most likely needs to run as r
 USBHID:
 
 ```
-./honeywell-config PAP131.
+$ ./honeywell-config PAP131.
+> PAP131.
+< PAP131.
 ```
 
 Keyboard:
 
 ```
-./honeywell-config PAP124.
+$ ./honeywell-config PAP124.
+> PAP124.
+< PAP124.
 ```
 
 ### Add Prefix to Output
@@ -49,7 +70,9 @@ Keyboard:
 The following adds the string `FCKAFD ` (ASCII hex `46 43 4B 41 46 44 20`) in front of every scanned barcode:
 
 ```
-./honeywell-config PREBK246434B41464420.
+$ ./honeywell-config PREBK246434B41464420.
+> PREBK246434B41464420.
+< PREBK246434B41464420.
 ```
 
 Note how this behaves differently from if you were to configure the scanner in-band via scanning config barcodes.
@@ -65,9 +88,38 @@ There you would scan a lot of individual codes from the manual:
 
 On the USB config interface, all of that goes into a single string instead.
 
+### Query Current Beeper Settings
+
+```
+$ ./honeywell-config 'BEP?.'
+> BEP?.
+< BEPFQ12550,FQ2100,RPT1,ERR1,BEP1,BIP0,LVL0,EXZ,GRX,EXE,DFT,LED1.
+```
+
+### List all Settings and Their Possible Values
+
+```
+$ ./honeywell-config '*.'
+> *.
+< BEPFQ1100-5000.
+< BEPFQ2100-5000.
+...
+< AXXMOD0|1|2|3|4|5|6|7|8|9|10.
+```
+
+## USB Device Access
+
+Please note that this tool normally needs to run as root.  Alternatively, you can set up a udev rule to grant access to the USB device to non-root users.
+
+An example for this can be found in the file `99-honeywell.rules`.
+Put this file into `/etc/udev/rules.d`, and run `sudo udevadm control --reload` to load the new ruleset.
+
+Once you replug the scanner, you should have access to it as a regular user.
+
 ## Adapting for Other Scanners
 
 The tool currently has hardcoded USB vendor/product IDs for a Honeywell Hyperion 1300G in Keyboard or USBHID modes.
+
 If you have a different Honeywell scanner, and the tool doesn't find it, you can try making this tool work for it:
 1. Obtain the USB vendor and product IDs for your scanner, e.g. through `lsusb`.
 1. Replace the VID/PID in the following line of code in `honeywell-config.c`:
@@ -75,7 +127,7 @@ If you have a different Honeywell scanner, and the tool doesn't find it, you can
     ```c
     libusb_device_handle *devh = libusb_open_device_with_vid_pid(ctx, 0x0c2e, 0x0b07);
     ```
-1. Recompile the tool with `make clean; make`
+1. Recompile the tool with `make`
 
 ## License
 

honeywell-config.c

@@ -1,21 +1,11 @@
 #include <stdio.h>
 #include <string.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/ioctl.h>
-#include <fcntl.h>
-#include <linux/ioctl.h>
-#include <linux/usbdevice_fs.h>
 #include <libusb-1.0/libusb.h>
 
-// Template for control messages, obtained through packet capture
-unsigned char *CMD = "\xfd\x00\x16M\r\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
-
 
 int main(int argc, char **argv) {
   uint8_t cmd[64];
-  memcpy(cmd, CMD, 64);
+  char tokbuf[1024];
-  struct usbdevfs_ioctl command;
   libusb_context *ctx = NULL;
 
   //
@@ -35,48 +25,114 @@ int main(int argc, char **argv) {
       return 1;
     }
   }
-  libusb_device *dev = libusb_get_device(devh);
-  if (!dev) {
-    perror("failed to get device info");
-    return 1;
-  }
 
   //
   // Disconnect usbhid driver from both device interfaces
   //
-  char usbdevfs[32];
+  if (libusb_set_auto_detach_kernel_driver(devh, 1)) {
-  snprintf(usbdevfs, 32, "/dev/bus/usb/%03d/%03d", libusb_get_bus_number(dev), libusb_get_device_address(dev));
+    perror("auto-attaching kernel driver not possible; please replug USB when done");
-  // usbdevfs/ioctl inspired from
+    for (uint8_t i = 0; i < 2; ++i) {
-  // https://www.linuxquestions.org/questions/linux-hardware-18/how-to-unclaim-usb-device-558138/#post3406986
+      int ret = libusb_kernel_driver_active(devh, i);
-  int fd = open(usbdevfs,O_RDWR);
+      if (ret < 0) {
-  if (fd < 1) {
+	perror("failed to query kernel driver state");
-    perror("failed to open usbdevfs file");
+	return 1;
-    return 1;
+      }
-  }
+      if (ret > 0) {
-  for (uint8_t i = 0; i < 2; ++i) {
+	ret = libusb_detach_kernel_driver(devh, i);
-    command.ifno = i;
+	if (ret) {
-    command.ioctl_code = USBDEVFS_DISCONNECT;
+	  perror("failed to detach kernel driver");
-    command.data = NULL;
+	  return 1;
-    int ret = ioctl(fd, USBDEVFS_IOCTL, &command);
+	}
-    if (ret < 0) {
+      }
-      perror("failed to unclaim USB interface from usbhid");
     }
   }
+  for (uint8_t i = 0; i < 2; ++i) {
+    if (libusb_claim_interface(devh, i)) {
+      perror("failed to claim interface");
+      return 1;
+    }
+  }
+
 
   //
   // Prepare and send a message on the control channel for each config argument
   //
   for (int i = 1; i < argc; ++i) {
     memset(cmd+5, 0, 59);
+    cmd[0] = 0xfd;
     cmd[1] = strlen(argv[i])+3;
+    cmd[2] = 0x16;
+    cmd[3] = 0x4d;
+    cmd[4] = 0x0d;
     memcpy(cmd+5, argv[i], strlen(argv[i]));
-    libusb_control_transfer(devh, 0x21, 0x09, 0x02fd, 1, cmd, 64, 0);
+    int ret = libusb_control_transfer(devh, 0x21, 0x09, 0x02fd, 1, cmd, 64, 0);
+    if (ret < 0) {
+      perror("failed to send control message");
+    } else {
+      printf("> %s\n", argv[i]);
+    }
+    int tx;
+    tokbuf[64] = 0;
+    char *start, *end, *tok = tokbuf;
+    uint8_t eot = 0;
+    // Repeat until a "." (EOT) is encountered in the response.
+    while (!eot) {
+      ret = libusb_interrupt_transfer(devh, 0x83, cmd, 64, &tx, 0);
+      if (ret) {
+	perror("failed to receive response");
+	break;
+      }
+      // strip 2-byte header and AIMID
+      start = cmd+5;
+      while (1) {
+	// non-final tokens: terminated by ;
+	end = strchr(start, ';');
+	if (end) {
+	  if (end > start) {
+	    memcpy(tok, start, end-start-1);
+	    tok += end-start-1;
+	  }
+	  *tok = 0;
+	  printf("< %s.\n", tokbuf);
+	  tok = tokbuf;
+	  *tok = 0;
+	  start = end + 1;
+	  continue;
+	}
+	// last token: terminated by .
+	end = strchr(start, '.');
+	if (end) {
+	  eot = 1;
+	  if (end > start) {
+	    memcpy(tok, start, end-start-1);
+	    tok += end-start-1;
+	  }
+	  *tok = 0;
+	  printf("< %s.\n", tokbuf);
+	  tok = tokbuf;
+	  *tok = 0;
+	  break;
+	}
+	// incomplete tokens continued in the next message
+	end = strchr(start, '?');
+	if (end) {
+	  *end = 0;
+	}
+	strcpy(tok, start);
+	tok += strlen(start);
+	break;
+      }
+    }
   }
 
   //
   // Cleanup
   //
-  libusb_release_interface(devh, 1);
+  for (uint8_t i = 0; i < 2; ++i) {
+    if (libusb_release_interface(devh, i)) {
+      perror("failed to release interface");
+    }
+  }
   libusb_close(devh);
   libusb_exit(ctx);
 }