Refactor Windows credential management to use direct API calls instead of cmdkey

internal/launcher/launcher.go

@@ -601,17 +601,7 @@ func (l *Launcher) storeWindowsCredential(conn *models.Connection) error {
 		username = fmt.Sprintf("%s\\%s", conn.Domain, conn.Username)
 	}
 
-	// Use cmdkey to store the credential
-	// cmdkey /generic:TERMSRV/hostname /user:username /pass:password
-	cmd := exec.Command("cmdkey", "/generic:TERMSRV/"+target, "/user:"+username, "/pass:"+conn.Password)
-	hideConsoleWindow(cmd)
-
-	output, err := cmd.CombinedOutput()
-	if err != nil {
-		return fmt.Errorf("cmdkey failed: %w, output: %s", err, string(output))
-	}
-
-	return nil
+	return writeWindowsCredential("TERMSRV/"+target, username, conn.Password)
 }
 
 // RemoveWindowsCredential removes RDP credentials from Windows Credential Manager
@@ -630,20 +620,7 @@ func (l *Launcher) RemoveWindowsCredential(conn *models.Connection) error {
 		target = fmt.Sprintf("%s:%d", conn.Host, port)
 	}
 
-	// Use cmdkey to delete the credential
-	// cmdkey /delete:TERMSRV/hostname
-	cmd := exec.Command("cmdkey", "/delete:TERMSRV/"+target)
-	hideConsoleWindow(cmd)
-
-	output, err := cmd.CombinedOutput()
-	if err != nil {
-		// Don't return error if credential doesn't exist
-		if !strings.Contains(string(output), "not found") {
-			return fmt.Errorf("cmdkey delete failed: %w, output: %s", err, string(output))
-		}
-	}
-
-	return nil
+	return deleteWindowsCredential("TERMSRV/" + target)
 }
 
 // CleanupAllCredentials removes all MremoteGO-stored credentials from Windows Credential Manager

internal/launcher/launcher_unix.go

@@ -11,3 +11,6 @@ import (
 func hideConsoleWindow(cmd *exec.Cmd) {
 	// Nothing to do on Unix-like systems
 }
+
+func writeWindowsCredential(target, username, password string) error { return nil }
+func deleteWindowsCredential(target string) error                    { return nil }

internal/launcher/launcher_windows.go

@@ -4,8 +4,11 @@
 package launcher
 
 import (
+	"fmt"
 	"os/exec"
+	"runtime"
 	"syscall"
+	"unsafe"
 )
 
 // hideConsoleWindow sets the command attributes to hide console windows on Windows
@@ -15,3 +18,84 @@ func hideConsoleWindow(cmd *exec.Cmd) {
 		CreationFlags: 0x08000000, // CREATE_NO_WINDOW
 	}
 }
+
+// writeWindowsCredential stores a generic credential in Windows Credential Manager
+// using CredWriteW directly, avoiding cmdkey's argument-parsing issues with
+// usernames or passwords that contain spaces or special characters.
+func writeWindowsCredential(target, username, password string) error {
+	credWriteW := syscall.NewLazyDLL("advapi32.dll").NewProc("CredWriteW")
+
+	targetPtr, err := syscall.UTF16PtrFromString(target)
+	if err != nil {
+		return fmt.Errorf("invalid target name: %w", err)
+	}
+	userPtr, err := syscall.UTF16PtrFromString(username)
+	if err != nil {
+		return fmt.Errorf("invalid username: %w", err)
+	}
+
+	// Encode password as UTF-16LE bytes without null terminator, as expected by
+	// Windows Credential Manager for RDP credentials consumed by mstsc.
+	passUTF16, err := syscall.UTF16FromString(password)
+	if err != nil {
+		return fmt.Errorf("invalid password: %w", err)
+	}
+	passUTF16 = passUTF16[:len(passUTF16)-1] // strip null terminator
+	passBlobSize := uint32(len(passUTF16) * 2)
+
+	// CREDENTIALW mirrors the Win32 CREDENTIALW struct layout.
+	type credentialW struct {
+		Flags              uint32
+		Type               uint32
+		TargetName         *uint16
+		Comment            *uint16
+		LastWritten        [2]uint32
+		CredentialBlobSize uint32
+		CredentialBlob     uintptr
+		Persist            uint32
+		AttributeCount     uint32
+		Attributes         uintptr
+		TargetAlias        *uint16
+		UserName           *uint16
+	}
+
+	var blobPtr uintptr
+	if passBlobSize > 0 {
+		blobPtr = uintptr(unsafe.Pointer(&passUTF16[0]))
+	}
+
+	cred := credentialW{
+		Type:               1, // CRED_TYPE_GENERIC
+		TargetName:         targetPtr,
+		UserName:           userPtr,
+		CredentialBlobSize: passBlobSize,
+		CredentialBlob:     blobPtr,
+		Persist:            2, // CRED_PERSIST_LOCAL_MACHINE
+	}
+
+	ret, _, callErr := credWriteW.Call(uintptr(unsafe.Pointer(&cred)), 0)
+	runtime.KeepAlive(passUTF16) // prevent GC until after the syscall
+	if ret == 0 {
+		return fmt.Errorf("CredWriteW failed: %w", callErr)
+	}
+	return nil
+}
+
+// deleteWindowsCredential removes a generic credential from Windows Credential Manager.
+// Returns nil if the credential does not exist.
+func deleteWindowsCredential(target string) error {
+	credDeleteW := syscall.NewLazyDLL("advapi32.dll").NewProc("CredDeleteW")
+
+	targetPtr, err := syscall.UTF16PtrFromString(target)
+	if err != nil {
+		return fmt.Errorf("invalid target name: %w", err)
+	}
+
+	const credTypeGeneric = 1
+	const errorNotFound = syscall.Errno(1168) // ERROR_NOT_FOUND
+	ret, _, callErr := credDeleteW.Call(uintptr(unsafe.Pointer(targetPtr)), credTypeGeneric, 0)
+	if ret == 0 && callErr != errorNotFound {
+		return fmt.Errorf("CredDeleteW failed: %w", callErr)
+	}
+	return nil
+}