From bb3f1932faa4f75800a145e7f0476d8a8dcf104a Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sun, 9 Jun 2019 17:22:59 +0200
Subject: setupapi: add DeviceInstanceID()

---
 tun/wintun/setupapi/setupapi_windows.go      | 23 +++++++++++++++++++++++
 tun/wintun/setupapi/setupapi_windows_test.go |  5 +++++
 tun/wintun/setupapi/zsetupapi_windows.go     | 13 +++++++++++++
 3 files changed, 41 insertions(+)

(limited to 'tun')

diff --git a/tun/wintun/setupapi/setupapi_windows.go b/tun/wintun/setupapi/setupapi_windows.go
index 1ac1419..6757743 100644
--- a/tun/wintun/setupapi/setupapi_windows.go
+++ b/tun/wintun/setupapi/setupapi_windows.go
@@ -364,6 +364,29 @@ func (deviceInfoSet DevInfo) DeviceInstallParams(deviceInfoData *DevInfoData) (*
 	return SetupDiGetDeviceInstallParams(deviceInfoSet, deviceInfoData)
 }
 
+//sys	setupDiGetDeviceInstanceId(deviceInfoSet DevInfo, deviceInfoData *DevInfoData, instanceId *uint16, instanceIdSize uint32, instanceIdRequiredSize *uint32) (err error) = setupapi.SetupDiGetDeviceInstanceIdW
+
+// SetupDiGetDeviceInstanceId function retrieves the instance ID of the device
+func SetupDiGetDeviceInstanceId(deviceInfoSet DevInfo, deviceInfoData *DevInfoData) (string, error) {
+	reqSize := uint32(1024)
+	for {
+		buf := make([]uint16, reqSize)
+		err := setupDiGetDeviceInstanceId(deviceInfoSet, deviceInfoData, &buf[0], uint32(len(buf)), &reqSize)
+		if err == windows.ERROR_INSUFFICIENT_BUFFER {
+			continue
+		}
+		if err != nil {
+			return "", err
+		}
+		return windows.UTF16ToString(buf), nil
+	}
+}
+
+// DeviceInstanceID method retrieves the instance ID of the device.
+func (deviceInfoSet DevInfo) DeviceInstanceID(deviceInfoData *DevInfoData) (string, error) {
+	return SetupDiGetDeviceInstanceId(deviceInfoSet, deviceInfoData)
+}
+
 // SetupDiGetClassInstallParams function retrieves class installation parameters for a device information set or a particular device information element.
 //sys	SetupDiGetClassInstallParams(deviceInfoSet DevInfo, deviceInfoData *DevInfoData, classInstallParams *ClassInstallHeader, classInstallParamsSize uint32, requiredSize *uint32) (err error) = setupapi.SetupDiGetClassInstallParamsW
 
diff --git a/tun/wintun/setupapi/setupapi_windows_test.go b/tun/wintun/setupapi/setupapi_windows_test.go
index b932d7d..48a0f05 100644
--- a/tun/wintun/setupapi/setupapi_windows_test.go
+++ b/tun/wintun/setupapi/setupapi_windows_test.go
@@ -139,6 +139,11 @@ func TestSetupDiEnumDeviceInfo(t *testing.T) {
 		if data.ClassGUID != deviceClassNetGUID {
 			t.Error("SetupDiEnumDeviceInfo returned different class GUID")
 		}
+
+		_, err = devInfoList.DeviceInstanceID(data)
+		if err != nil {
+			t.Errorf("Error calling SetupDiGetDeviceInstanceId: %s", err.Error())
+		}
 	}
 }
 
diff --git a/tun/wintun/setupapi/zsetupapi_windows.go b/tun/wintun/setupapi/zsetupapi_windows.go
index 248672e..0949718 100644
--- a/tun/wintun/setupapi/zsetupapi_windows.go
+++ b/tun/wintun/setupapi/zsetupapi_windows.go
@@ -57,6 +57,7 @@ var (
 	procSetupDiGetDeviceRegistryPropertyW = modsetupapi.NewProc("SetupDiGetDeviceRegistryPropertyW")
 	procSetupDiSetDeviceRegistryPropertyW = modsetupapi.NewProc("SetupDiSetDeviceRegistryPropertyW")
 	procSetupDiGetDeviceInstallParamsW    = modsetupapi.NewProc("SetupDiGetDeviceInstallParamsW")
+	procSetupDiGetDeviceInstanceIdW       = modsetupapi.NewProc("SetupDiGetDeviceInstanceIdW")
 	procSetupDiGetClassInstallParamsW     = modsetupapi.NewProc("SetupDiGetClassInstallParamsW")
 	procSetupDiSetDeviceInstallParamsW    = modsetupapi.NewProc("SetupDiSetDeviceInstallParamsW")
 	procSetupDiSetClassInstallParamsW     = modsetupapi.NewProc("SetupDiSetClassInstallParamsW")
@@ -285,6 +286,18 @@ func setupDiGetDeviceInstallParams(deviceInfoSet DevInfo, deviceInfoData *DevInf
 	return
 }
 
+func setupDiGetDeviceInstanceId(deviceInfoSet DevInfo, deviceInfoData *DevInfoData, instanceId *uint16, instanceIdSize uint32, instanceIdRequiredSize *uint32) (err error) {
+	r1, _, e1 := syscall.Syscall6(procSetupDiGetDeviceInstanceIdW.Addr(), 5, uintptr(deviceInfoSet), uintptr(unsafe.Pointer(deviceInfoData)), uintptr(unsafe.Pointer(instanceId)), uintptr(instanceIdSize), uintptr(unsafe.Pointer(instanceIdRequiredSize)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
 func SetupDiGetClassInstallParams(deviceInfoSet DevInfo, deviceInfoData *DevInfoData, classInstallParams *ClassInstallHeader, classInstallParamsSize uint32, requiredSize *uint32) (err error) {
 	r1, _, e1 := syscall.Syscall6(procSetupDiGetClassInstallParamsW.Addr(), 5, uintptr(deviceInfoSet), uintptr(unsafe.Pointer(deviceInfoData)), uintptr(unsafe.Pointer(classInstallParams)), uintptr(classInstallParamsSize), uintptr(unsafe.Pointer(requiredSize)), 0)
 	if r1 == 0 {
-- 
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