Var consolidation and make joinOU optional to match win32 api call.

go/domain/join.go

@@ -25,17 +25,6 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-const (
-	// Known error codes
-	// nErrSuccess is the value returned on a successful run of NetJoinDomain.
-	// https://docs.microsoft.com/en-us/windows/win32/api/lmjoin/nf-lmjoin-netjoindomain#return-value
-	nErrSuccess = 0
-
-	// Domain Join constants
-	// https://learn.microsoft.com/en-us/windows/win32/api/lmjoin/nf-lmjoin-netjoindomain#parameters
-	server = 0 // use the local machine name
-)
-
 // DomainJoinOptions specifies options for the domain join operation.
 // See https://learn.microsoft.com/en-us/windows/win32/api/lmjoin/nf-lmjoin-netjoindomain
 type DomainJoinOptions uint32
@@ -73,7 +62,8 @@ var (
 	netJoinDomain     = prodNetJoinDomain.Call
 )
 
-// Domain joins a client to a domain.
+// Domain joins the local machine to a domain.
+// See https://learn.microsoft.com/en-us/windows/win32/api/lmjoin/nf-lmjoin-netjoindomain for more details.
 func Domain(domain, joinOU, joinAccount, joinPassword string, options DomainJoinOptions) error {
 
 	dom, err := windows.UTF16PtrFromString(domain)
@@ -84,23 +74,28 @@ func Domain(domain, joinOU, joinAccount, joinPassword string, options DomainJoin
 	if err != nil {
 		return err
 	}
-	ou, err := windows.UTF16PtrFromString(joinOU)
-	if err != nil {
-		return err
+	var ou *uint16
+	if joinOU != "" {
+		var err error
+		ou, err = windows.UTF16PtrFromString(joinOU)
+		if err != nil {
+			return err
+		}
 	}
 	pw, err := windows.UTF16PtrFromString(joinPassword)
 	if err != nil {
 		return err
 	}
 	fmt.Printf("Attempting domain join with domain: %s, OU: %s, account: %s\n", domain, joinOU, joinAccount)
+	// https://learn.microsoft.com/en-us/windows/win32/api/lmjoin/nf-lmjoin-netjoindomain#parameters
 	if returnCode, _, _ := netJoinDomain(
-		server,                       // lpServer
+		0,                            // lpServer, 0 / Null means use the local machine.
 		uintptr(unsafe.Pointer(dom)), // lpDomain
 		uintptr(unsafe.Pointer(ou)),  // lpMachineAccountOU
 		uintptr(unsafe.Pointer(acc)), // lpAccount
 		uintptr(unsafe.Pointer(pw)),  // lpPassword
 		uintptr(options),             // fJoinOptions
-	); returnCode != nErrSuccess {
+	); windows.Errno(returnCode) != windows.ERROR_SUCCESS {
 		return fmt.Errorf("failed to join domain: %w", windows.Errno(returnCode))
 	}
 

go/domain/join_test.go

@@ -42,7 +42,7 @@ func TestDomain(t *testing.T) {
 	}{
 		{
 			name:    "success",
-			retCode: nErrSuccess,
+			retCode: 0,
 		},
 		{
 			name:    "failure",