Add device agent library

Provide enrollment, elevated install, posture checks, keystore, and
system-tray helpers shared by the probo-agent binary.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

pkg/deviceagent/tray/console_user_windows.go

@@ -0,0 +1,213 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+//go:build windows
+
+package tray
+
+import (
+	"fmt"
+	"strings"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+const invalidSessionID = 0xFFFFFFFF
+
+func currentInteractiveUserSID() (string, error) {
+	var lastErr error
+
+	for _, sessionID := range interactiveSessionCandidates() {
+		sid, err := sidFromSessionID(sessionID)
+		if err == nil {
+			return sid, nil
+		}
+
+		lastErr = err
+	}
+
+	if lastErr != nil {
+		return "", fmt.Errorf("no interactive user session available: %w", lastErr)
+	}
+
+	return "", fmt.Errorf("no interactive user session available")
+}
+
+func interactiveSessionCandidates() []uint32 {
+	candidates := make([]uint32, 0, 4)
+
+	var sessionID uint32
+
+	if err := windows.ProcessIdToSessionId(windows.GetCurrentProcessId(), &sessionID); err == nil && sessionID != 0 {
+		candidates = appendUniqueSessionID(candidates, sessionID)
+	}
+
+	consoleSessionID := windows.WTSGetActiveConsoleSessionId()
+	if consoleSessionID != invalidSessionID {
+		candidates = appendUniqueSessionID(candidates, consoleSessionID)
+	}
+
+	for _, id := range activeWTSSessionIDs() {
+		candidates = appendUniqueSessionID(candidates, id)
+	}
+
+	return candidates
+}
+
+func activeWTSSessionIDs() []uint32 {
+	var (
+		sessions *windows.WTS_SESSION_INFO
+		count    uint32
+	)
+
+	if err := windows.WTSEnumerateSessions(0, 0, 1, &sessions, &count); err != nil {
+		return nil
+	}
+
+	defer windows.WTSFreeMemory(uintptr(unsafe.Pointer(sessions)))
+
+	sessionSlice := unsafe.Slice(sessions, count)
+
+	ids := make([]uint32, 0, len(sessionSlice))
+	for _, session := range sessionSlice {
+		if session.SessionID == 0 {
+			continue
+		}
+
+		if session.State != windows.WTSActive && session.State != windows.WTSConnected {
+			continue
+		}
+
+		ids = append(ids, session.SessionID)
+	}
+
+	return ids
+}
+
+func appendUniqueSessionID(ids []uint32, sessionID uint32) []uint32 {
+	for _, id := range ids {
+		if id == sessionID {
+			return ids
+		}
+	}
+
+	return append(ids, sessionID)
+}
+
+func sidFromSessionID(sessionID uint32) (string, error) {
+	sid, err := sidFromSessionInformation(sessionID)
+	if err == nil {
+		return sid, nil
+	}
+
+	if isCurrentProcessLocalSystem() {
+		if sid, tokenErr := sidFromSessionUserToken(sessionID); tokenErr == nil {
+			return sid, nil
+		}
+	}
+
+	return "", err
+}
+
+func sidFromSessionInformation(sessionID uint32) (string, error) {
+	user, domain, err := sessionUserAndDomain(sessionID)
+	if err != nil {
+		return "", err
+	}
+
+	account := user
+	system := ""
+	if domain != "" {
+		account = domain + `\` + user
+	}
+
+	sid, _, _, err := windows.LookupSID(system, account)
+	if err != nil {
+		return "", fmt.Errorf("cannot lookup session %d user SID: %w", sessionID, err)
+	}
+
+	sidStr := sid.String()
+	if sidStr == "" {
+		return "", fmt.Errorf("session %d user SID is empty", sessionID)
+	}
+
+	if !isInteractiveUserSID(sidStr) {
+		return "", fmt.Errorf("session %d has no interactive user", sessionID)
+	}
+
+	return sidStr, nil
+}
+
+func sidFromSessionUserToken(sessionID uint32) (string, error) {
+	var token windows.Token
+
+	if err := windows.WTSQueryUserToken(sessionID, &token); err != nil {
+		return "", fmt.Errorf("cannot query session %d user token: %w", sessionID, err)
+	}
+
+	defer func() { _ = token.Close() }()
+
+	tu, err := token.GetTokenUser()
+	if err != nil {
+		return "", fmt.Errorf("cannot read session %d user: %w", sessionID, err)
+	}
+
+	if tu.User.Sid == nil {
+		return "", fmt.Errorf("session %d user SID is empty", sessionID)
+	}
+
+	sid := tu.User.Sid.String()
+	if sid == "" {
+		return "", fmt.Errorf("session %d user SID is empty", sessionID)
+	}
+
+	if !isInteractiveUserSID(sid) {
+		return "", fmt.Errorf("session %d has no interactive user", sessionID)
+	}
+
+	return sid, nil
+}
+
+func isCurrentProcessLocalSystem() bool {
+	token, err := windows.OpenCurrentProcessToken()
+	if err != nil {
+		return false
+	}
+
+	defer func() { _ = token.Close() }()
+
+	tu, err := token.GetTokenUser()
+	if err != nil {
+		return false
+	}
+
+	systemSID, err := windows.CreateWellKnownSid(windows.WinLocalSystemSid)
+	if err != nil {
+		return false
+	}
+
+	return tu.User.Sid.Equals(systemSID)
+}
+
+func isInteractiveUserSID(sid string) bool {
+	return strings.HasPrefix(sid, "S-1-5-21-") ||
+		strings.HasPrefix(sid, "S-1-12-1-")
+}