Converted most metrics to non-wmi

Signed-off-by: Ben Ridley <benridley29@gmail.com>

headers/netapi32/netapi32.go

@@ -0,0 +1,89 @@
+package netapi32
+
+import (
+	"errors"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// WKSTAInfo102 is a wrapper of WKSTA_Info_102
+//https://docs.microsoft.com/en-us/windows/win32/api/lmwksta/ns-lmwksta-wksta_info_102
+type WKSTAInfo102 struct {
+	Wki102_platform_id     uint32
+	wki102_computername    *uint16
+	wki102_langroup        *uint16
+	Wki102_ver_major       uint32
+	Wki102_ver_minor       uint32
+	wki102_lanroot         *uint16
+	Wki102_logged_on_users uint32
+}
+
+var (
+	netapi32             = windows.NewLazySystemDLL("netapi32")
+	procNetWkstaGetInfo  = netapi32.NewProc("NetWkstaGetInfo")
+	procNetApiBufferFree = netapi32.NewProc("NetApiBufferFree")
+)
+
+// NetApiStatus is a map of Network Management Error Codes.
+// https://docs.microsoft.com/en-gb/windows/win32/netmgmt/network-management-error-codes?redirectedfrom=MSDN
+var NetApiStatus = map[uint32]string{
+	// Success
+	0: "NERR_Success",
+	// This computer name is invalid.
+	2351: "NERR_InvalidComputer",
+	// This operation is only allowed on the primary domain controller of the domain.
+	2226: "NERR_NotPrimary",
+	/// This operation is not allowed on this special group.
+	2234: "NERR_SpeGroupOp",
+	/// This operation is not allowed on the last administrative account.
+	2452: "NERR_LastAdmin",
+	/// The password parameter is invalid.
+	2203: "NERR_BadPassword",
+	/// The password does not meet the password policy requirements.
+	/// Check the minimum password length, password complexity and password history requirements.
+	2245: "NERR_PasswordTooShort",
+	/// The user name could not be found.
+	2221: "NERR_UserNotFound",
+	// Errors
+	5:    "ERROR_ACCESS_DENIED",
+	8:    "ERROR_NOT_ENOUGH_MEMORY",
+	87:   "ERROR_INVALID_PARAMETER",
+	123:  "ERROR_INVALID_NAME",
+	124:  "ERROR_INVALID_LEVEL",
+	234:  "ERROR_MORE_DATA",
+	1219: "ERROR_SESSION_CREDENTIAL_CONFLICT",
+}
+
+// NetApiBufferFree frees the memory other network management functions use internally to return information.
+// https://docs.microsoft.com/en-us/windows/win32/api/lmapibuf/nf-lmapibuf-netapibufferfree
+func NetApiBufferFree(buffer *WKSTAInfo102) {
+	procNetApiBufferFree.Call(uintptr(unsafe.Pointer(buffer)))
+}
+
+// NetWkstaGetInfo returns information about the configuration of a workstation.
+// https://docs.microsoft.com/en-us/windows/win32/api/lmwksta/nf-lmwksta-netwkstagetinfo
+func NetWkstaGetInfo() (WKSTAInfo102, uint32, error) {
+	// Struct
+	var lpwi *WKSTAInfo102
+	pLpwi := uintptr(unsafe.Pointer(&lpwi))
+
+	// Null value
+	var nullptr = uintptr(0)
+
+	// Level
+	pLevel := uintptr(102)
+
+	// Func call
+	r1, _, _ := procNetWkstaGetInfo.Call(nullptr, pLevel, pLpwi)
+
+	if ret := *(*uint32)(unsafe.Pointer(&r1)); ret != 0 {
+		return WKSTAInfo102{}, ret, errors.New(NetApiStatus[ret])
+	}
+
+	// Derence the pointer and return the object so we can safely clear the buffer.
+	var deref WKSTAInfo102 = *lpwi
+	defer NetApiBufferFree(lpwi)
+
+	return deref, 0, nil
+}