From bb193503d4066d38bc40a46e603bdc5909e7c243 Mon Sep 17 00:00:00 2001
From: Juan <994594+juaoose@users.noreply.github.com>
Date: Wed, 15 May 2024 13:23:47 -0500
Subject: [PATCH 1/2] Add unknown interface descriptors to Extra

---
 interface.go | 2 ++
 libusb.go    | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/interface.go b/interface.go
index 0af77a9..8439ffa 100644
--- a/interface.go
+++ b/interface.go
@@ -51,6 +51,8 @@ type InterfaceSetting struct {
 	// Endpoints enumerates the endpoints available on this interface with
 	// this alternate setting.
 	Endpoints map[EndpointAddress]EndpointDesc
+	// Unknown interface descriptors
+	Extra []byte
 
 	iInterface int // index of a string descriptor describing this interface.
 }
diff --git a/libusb.go b/libusb.go
index ddc0b2a..76937f2 100644
--- a/libusb.go
+++ b/libusb.go
@@ -301,12 +301,14 @@ func (libusbImpl) getDeviceDesc(d *libusbDevice) (*DeviceDesc, error) {
 			}
 			descs := make([]InterfaceSetting, 0, len(alts))
 			for _, alt := range alts {
+
 				i := InterfaceSetting{
 					Number:     int(alt.bInterfaceNumber),
 					Alternate:  int(alt.bAlternateSetting),
 					Class:      Class(alt.bInterfaceClass),
 					SubClass:   Class(alt.bInterfaceSubClass),
 					Protocol:   Protocol(alt.bInterfaceProtocol),
+					Extra:      C.GoBytes(unsafe.Pointer(alt.extra), alt.extra_length),
 					iInterface: int(alt.iInterface),
 				}
 

From 965a4971f089eb3d86106bfc0426ed1e22ed6d7b Mon Sep 17 00:00:00 2001
From: Juan <994594+juaoose@users.noreply.github.com>
Date: Thu, 16 May 2024 20:01:23 -0500
Subject: [PATCH 2/2] Update after comments

---
 constants.go | 19 ++++++++++---------
 interface.go | 10 ++++++++--
 libusb.go    | 27 ++++++++++++++++++++-------
 3 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/constants.go b/constants.go
index aa1ce40..a301aad 100644
--- a/constants.go
+++ b/constants.go
@@ -94,15 +94,16 @@ type DescriptorType uint8
 
 // Descriptor types defined by the USB spec.
 const (
-	DescriptorTypeDevice    DescriptorType = C.LIBUSB_DT_DEVICE
-	DescriptorTypeConfig    DescriptorType = C.LIBUSB_DT_CONFIG
-	DescriptorTypeString    DescriptorType = C.LIBUSB_DT_STRING
-	DescriptorTypeInterface DescriptorType = C.LIBUSB_DT_INTERFACE
-	DescriptorTypeEndpoint  DescriptorType = C.LIBUSB_DT_ENDPOINT
-	DescriptorTypeHID       DescriptorType = C.LIBUSB_DT_HID
-	DescriptorTypeReport    DescriptorType = C.LIBUSB_DT_REPORT
-	DescriptorTypePhysical  DescriptorType = C.LIBUSB_DT_PHYSICAL
-	DescriptorTypeHub       DescriptorType = C.LIBUSB_DT_HUB
+	DescriptorTypeDevice      DescriptorType = C.LIBUSB_DT_DEVICE
+	DescriptorTypeConfig      DescriptorType = C.LIBUSB_DT_CONFIG
+	DescriptorTypeString      DescriptorType = C.LIBUSB_DT_STRING
+	DescriptorTypeInterface   DescriptorType = C.LIBUSB_DT_INTERFACE
+	DescriptorTypeCSInterface DescriptorType = 0x24
+	DescriptorTypeEndpoint    DescriptorType = C.LIBUSB_DT_ENDPOINT
+	DescriptorTypeHID         DescriptorType = C.LIBUSB_DT_HID
+	DescriptorTypeReport      DescriptorType = C.LIBUSB_DT_REPORT
+	DescriptorTypePhysical    DescriptorType = C.LIBUSB_DT_PHYSICAL
+	DescriptorTypeHub         DescriptorType = C.LIBUSB_DT_HUB
 )
 
 var descriptorTypeDescription = map[DescriptorType]string{
diff --git a/interface.go b/interface.go
index 8439ffa..0ae125f 100644
--- a/interface.go
+++ b/interface.go
@@ -35,6 +35,11 @@ func (i InterfaceDesc) String() string {
 	return fmt.Sprintf("Interface %d (%d alternate settings)", i.Number, len(i.AltSettings))
 }
 
+type RawDescriptor struct {
+	Type DescriptorType
+	Data []byte
+}
+
 // InterfaceSetting contains information about a USB interface with a particular
 // alternate setting, extracted from the descriptor.
 type InterfaceSetting struct {
@@ -51,8 +56,9 @@ type InterfaceSetting struct {
 	// Endpoints enumerates the endpoints available on this interface with
 	// this alternate setting.
 	Endpoints map[EndpointAddress]EndpointDesc
-	// Unknown interface descriptors
-	Extra []byte
+	// Extra interface descriptors, these are descriptors that are not part of the USB spec
+	// Potential examples are Class-Specific VC Interface Descriptor (UVC spec)
+	ExtraDescriptors []*RawDescriptor
 
 	iInterface int // index of a string descriptor describing this interface.
 }
diff --git a/libusb.go b/libusb.go
index 76937f2..b380ea5 100644
--- a/libusb.go
+++ b/libusb.go
@@ -302,14 +302,27 @@ func (libusbImpl) getDeviceDesc(d *libusbDevice) (*DeviceDesc, error) {
 			descs := make([]InterfaceSetting, 0, len(alts))
 			for _, alt := range alts {
 
+				var extraDescriptors []*RawDescriptor
+				extra := C.GoBytes(unsafe.Pointer(alt.extra), alt.extra_length)
+				for i := 0; i != len(extra); i += int(extra[i]) {
+					block := extra[i : i+int(extra[i])]
+					bType := DescriptorType(block[1])
+
+					extraDescriptors = append(extraDescriptors,
+						&RawDescriptor{
+							Type: bType,
+							Data: block},
+					)
+				}
+
 				i := InterfaceSetting{
-					Number:     int(alt.bInterfaceNumber),
-					Alternate:  int(alt.bAlternateSetting),
-					Class:      Class(alt.bInterfaceClass),
-					SubClass:   Class(alt.bInterfaceSubClass),
-					Protocol:   Protocol(alt.bInterfaceProtocol),
-					Extra:      C.GoBytes(unsafe.Pointer(alt.extra), alt.extra_length),
-					iInterface: int(alt.iInterface),
+					Number:           int(alt.bInterfaceNumber),
+					Alternate:        int(alt.bAlternateSetting),
+					Class:            Class(alt.bInterfaceClass),
+					SubClass:         Class(alt.bInterfaceSubClass),
+					Protocol:         Protocol(alt.bInterfaceProtocol),
+					ExtraDescriptors: extraDescriptors,
+					iInterface:       int(alt.iInterface),
 				}
 
 				if hasIntf[i.Number][i.Alternate] {