Implemented reading ContainerID from BOS descriptor to detect USB2/3 dual devices

Per USB 3.0 spec, chapter 11.2:

> Within a USB 3.0 hub, both the SuperSpeed and USB 2.0 hub devices shall implement in the hub framework
> a common standardized ContainerID to enable software to identify the physical relationship of the hub devices.
> The ContainerID descriptor is a part of the BOS descriptor set.

* Read ContainerID from BOS descriptor.
* get_device_description() now returns struct with vendor, product, serial number as well as full description.
* Use ContainerID to improve finding dual hubs. This seems to work very well on any OS.
  However, this may still fail if two or more identical hubs use the same hardcoded ContainerID
  In this case, we still try to look for other clues like serial number match if possible.

This fixes issue #161.

Author: mvp

uhubctl.c

@@ -178,16 +178,24 @@ struct usb_port_status {
 /* List of all USB devices enumerated by libusb */
 static struct libusb_device **usb_devs = NULL;
 
+struct descriptor_strings {
+    char vendor[64];
+    char product[64];
+    char serial[64];
+    char description[256];
+};
+
 struct hub_info {
     struct libusb_device *dev;
     int bcd_usb;
     int nports;
     int ppps;
     int actionable; /* true if this hub is subject to action */
+    char container_id[33]; /* container ID as hex string */
     char vendor[16];
     char location[32];
     int level;
-    char description[256];
+    struct descriptor_strings ds;
 };
 
 /* Array of all enumerated USB hubs */
@@ -415,6 +423,28 @@ static int get_hub_info(struct libusb_device *dev, struct hub_info *info)
         } else {
             rc = len;
         }
+        /* Get container_id: */
+        bzero(info->container_id, sizeof(info->container_id));
+        struct libusb_bos_descriptor *bos;
+        rc = libusb_get_bos_descriptor(devh, &bos);
+        if (rc == 0) {
+            int cap;
+            for (cap=0; cap < bos->bNumDeviceCaps; cap++) {
+                if (bos->dev_capability[cap]->bDevCapabilityType == LIBUSB_BT_CONTAINER_ID) {
+                    struct libusb_container_id_descriptor *container_id;
+                    rc = libusb_get_container_id_descriptor(NULL, bos->dev_capability[cap], &container_id);
+                    if (rc == 0) {
+                        int i;
+                        for (i=0; i<16; i++) {
+                            sprintf(info->container_id+i*2, "%02x", container_id->ContainerID[i]);
+                        }
+                        info->container_id[i*2] = 0;
+                        libusb_free_container_id_descriptor(container_id);
+                    }
+                }
+            }
+            libusb_free_bos_descriptor(bos);
+        }
         libusb_close(devh);
     }
     return rc;
@@ -450,52 +480,50 @@ static int get_port_status(struct libusb_device_handle *devh, int port)
 
 
 /*
- * Get USB device description as a string.
+ * Get USB device descriptor strings and summary description.
  *
- * It will use following format:
+ * Summary will use following format:
  *
  *    "<vid:pid> <vendor> <product> <serial>, <USB x.yz, N ports>"
  *
  * vid:pid will be always present, but vendor, product or serial
  * may be skipped if they are empty or not enough permissions to read them.
  * <USB x.yz, N ports> will be present only for USB hubs.
  *
- * returns 0 for success and error code for failure.
- * in case of failure description buffer is not altered.
+ * Returns 0 for success and error code for failure.
+ * In case of failure return buffer is not altered.
  */
 
-static int get_device_description(struct libusb_device * dev, char* description, int desc_len)
+static int get_device_description(struct libusb_device * dev, struct descriptor_strings * ds)
 {
     int rc;
     int id_vendor  = 0;
     int id_product = 0;
-    char vendor[64]  = "";
-    char product[64] = "";
-    char serial[64]  = "";
     char ports[64]   = "";
     struct libusb_device_descriptor desc;
     struct libusb_device_handle *devh = NULL;
     rc = libusb_get_device_descriptor(dev, &desc);
     if (rc)
         return rc;
+    bzero(ds, sizeof(*ds));
     id_vendor  = libusb_le16_to_cpu(desc.idVendor);
     id_product = libusb_le16_to_cpu(desc.idProduct);
     rc = libusb_open(dev, &devh);
     if (rc == 0) {
         if (desc.iManufacturer) {
             libusb_get_string_descriptor_ascii(devh,
-                desc.iManufacturer, (unsigned char*)vendor, sizeof(vendor));
-            rtrim(vendor);
+                desc.iManufacturer, (unsigned char*)ds->vendor, sizeof(ds->vendor));
+            rtrim(ds->vendor);
         }
         if (desc.iProduct) {
             libusb_get_string_descriptor_ascii(devh,
-                desc.iProduct, (unsigned char*)product, sizeof(product));
-            rtrim(product);
+                desc.iProduct, (unsigned char*)ds->product, sizeof(ds->product));
+            rtrim(ds->product);
         }
         if (desc.iSerialNumber) {
             libusb_get_string_descriptor_ascii(devh,
-                desc.iSerialNumber, (unsigned char*)serial, sizeof(serial));
-            rtrim(serial);
+                desc.iSerialNumber, (unsigned char*)ds->serial, sizeof(ds->serial));
+            rtrim(ds->serial);
         }
         if (desc.bDeviceClass == LIBUSB_CLASS_HUB) {
             struct hub_info info;
@@ -507,12 +535,12 @@ static int get_device_description(struct libusb_device * dev, char* description,
         }
         libusb_close(devh);
     }
-    snprintf(description, desc_len,
+    snprintf(ds->description, sizeof(ds->description),
         "%04x:%04x%s%s%s%s%s%s%s",
         id_vendor, id_product,
-        vendor[0]  ? " " : "", vendor,
-        product[0] ? " " : "", product,
-        serial[0]  ? " " : "", serial,
+        ds->vendor[0]  ? " " : "", ds->vendor,
+        ds->product[0] ? " " : "", ds->product,
+        ds->serial[0]  ? " " : "", ds->serial,
         ports
     );
     return 0;
@@ -555,7 +583,8 @@ static int print_port_status(struct hub_info * hub, int portmask)
 
             printf("  Port %d: %04x", port, port_status);
 
-            char description[256] = "";
+            struct descriptor_strings ds;
+            bzero(&ds, sizeof(ds));
             struct libusb_device * udev;
             int i = 0;
             while ((udev = usb_devs[i++]) != NULL) {
@@ -567,7 +596,7 @@ static int print_port_status(struct hub_info * hub, int portmask)
                     (memcmp(hub_pn, dev_pn, hub_plen) == 0) &&
                     libusb_get_port_number(udev) == port)
                 {
-                    rc = get_device_description(udev, description, sizeof(description));
+                    rc = get_device_description(udev, &ds);
                     if (rc == 0)
                         break;
                 }
@@ -614,7 +643,7 @@ static int print_port_status(struct hub_info * hub, int portmask)
             if (port_status & USB_PORT_STAT_ENABLE)      printf(" enable");
             if (port_status & USB_PORT_STAT_CONNECTION)  printf(" connect");
 
-            if (port_status & USB_PORT_STAT_CONNECTION)  printf(" [%s]", description);
+            if (port_status & USB_PORT_STAT_CONNECTION)  printf(" [%s]", ds.description);
 
             printf("\n");
         }
@@ -652,7 +681,7 @@ static int usb_find_hubs()
         if (rc) {
             perm_ok = 0; /* USB permission issue? */
         }
-        get_device_description(dev, info.description, sizeof(info.description));
+        get_device_description(dev, &info.ds);
         if (info.ppps) { /* PPPS is supported */
             if (hub_count < MAX_HUBS) {
                 info.actionable = 1;
@@ -682,63 +711,51 @@ static int usb_find_hubs()
             /* Check only actionable hubs: */
             if (hubs[i].actionable != 1)
                 continue;
+            /* Must have non empty container ID: */
+            if (strlen(hubs[i].container_id) == 0)
+                continue;
             int match = -1;
             for (j=0; j<hub_count; j++) {
                 if (i==j)
                     continue;
 
-                /* Find hub which is USB2/3 dual to the hub above.
-                 * This is quite reliable and predictable on Linux
-                 * but not on Mac, where we may match wrong hub :(
-                 * It will work reliably on Mac if there is
-                 * only one compatible USB3 hub is connected.
-                 * Unfortunately, libusb does not provide any way
-                 * to detect USB2/3 dual hubs.
-                 * TODO: discover better way to find dual hub.
-                 */
+                /* Find hub which is USB2/3 dual to the hub above */
 
                 /* Hub and its dual must be different types: one USB2, another USB3: */
                 if ((hubs[i].bcd_usb < USB_SS_BCD) ==
                     (hubs[j].bcd_usb < USB_SS_BCD))
                     continue;
 
-                /* But they must have the same vendor: */
-                if (strncasecmp(hubs[i].vendor, hubs[j].vendor, 4))
+                /* Must have non empty container ID: */
+                if (strlen(hubs[j].container_id) == 0)
+                    continue;
+
+                /* Per USB 3.0 spec chapter 11.2, container IDs must match: */
+                if (strcmp(hubs[i].container_id, hubs[j].container_id) != 0)
                     continue;
 
-                /* And the same number of ports: */
+                /* At this point, it should be enough to claim a match.
+                 * However, some devices use hardcoded non-unique container ID.
+                 * We should do few more checks below if multiple such devices are present.
+                 */
+
+                /* If serial number is present, it must match: */
+                if ((strlen(hubs[i].ds.serial) > 0 || strlen(hubs[j].ds.serial) > 0) &&
+                    strcmp(hubs[i].ds.serial, hubs[j].ds.serial) != 0)
+                {
+                    continue;
+                }
+
+                /* Hubs should have the same number of ports: */
                 if (hubs[i].nports != hubs[j].nports)
                     continue;
 
                 /* And the same level: */
                 if (hubs[i].level != hubs[j].level)
                     continue;
 
-                /* If description is the same, provisionally we choose this one as dual.
-                 * If description contained serial number, this will be most reliable matching.
-                 */
-                if (strlen(hubs[i].description) == strlen(hubs[j].description)) {
-                    /* strlen("vvvv:pppp ") + strlen(", USB x.yz, N ports") = 10+19 = 29 */
-                    if (strlen(hubs[i].description) >= 29) {
-                        if (strncmp(hubs[i].description+10, hubs[j].description+10, strlen(hubs[i].description)-29) == 0) {
-                            match = j;
-                        }
-                    }
-                }
-
-                /* Running out of options - provisionally we choose this one as dual: */
-                if (match < 0 && !hubs[j].actionable)
-                    match = j;
-
-                /* But if there is exact port path match,
-                 * we prefer it (true for Linux but not Mac):
-                 */
-                char *p1 = strchr(hubs[i].location, '-');
-                char *p2 = strchr(hubs[j].location, '-');
-                if (p1 && p2 && strcasecmp(p1, p2)==0) {
-                    match = j;
-                    break;
-                }
+                /* Finally, we claim a match: */
+                match = j;
             }
             if (match >= 0) {
                 if (!hubs[match].actionable) {
@@ -912,7 +929,7 @@ int main(int argc, char *argv[])
             if (hubs[i].actionable == 0)
                 continue;
             printf("Current status for hub %s [%s]\n",
-                hubs[i].location, hubs[i].description
+                hubs[i].location, hubs[i].ds.description
             );
             print_port_status(&hubs[i], opt_ports);
             if (opt_action == POWER_KEEP) { /* no action, show status */
@@ -962,7 +979,7 @@ int main(int argc, char *argv[])
                     request == LIBUSB_REQUEST_CLEAR_FEATURE ? "off" : "on"
                 );
                 printf("New status for hub %s [%s]\n",
-                    hubs[i].location, hubs[i].description
+                    hubs[i].location, hubs[i].ds.description
                 );
                 print_port_status(&hubs[i], opt_ports);