22e50b3f11
Introduce the standalone device agent binary and shared library for enrollment, posture checks, self-update, and OS service integration. Include build targets, module deps, and release workflow so the agent can ship independently of server changes. Signed-off-by: Bryan Frimin <bryan@probo.com>
111 lines
3.2 KiB
Go
111 lines
3.2 KiB
Go
// Copyright (c) 2025-2026 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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//go:build windows
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package update
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import (
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"errors"
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"fmt"
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"io"
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"os"
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"path/filepath"
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)
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const oldSuffix = ".old"
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// replaceBinary swaps dst with src on Windows.
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//
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// Windows blocks deletion / replacement of the running .exe but does
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// allow renaming a locked .exe out of the way. We:
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//
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// 1. Stage src as `<dst>.new` (same directory, so the final rename is
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// just a metadata update and won't cross volumes).
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// 2. Move the running binary to `<dst>.old` (NTFS lets us rename a
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// locked exe).
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// 3. Move `<dst>.new` into place at `<dst>`.
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//
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// On the next start the agent's main() calls CleanupAfterRestart to
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// best-effort delete `<dst>.old`.
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func replaceBinary(dst, src string) error {
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staging := dst + ".new"
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if err := copyFile(src, staging); err != nil {
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return err
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}
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oldPath := dst + oldSuffix
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_ = os.Remove(oldPath)
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if err := os.Rename(dst, oldPath); err != nil && !errors.Is(err, os.ErrNotExist) {
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_ = os.Remove(staging)
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return fmt.Errorf("cannot move running binary aside: %w", err)
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}
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if err := os.Rename(staging, dst); err != nil {
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// Try to roll back the running binary swap.
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_ = os.Rename(oldPath, dst)
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_ = os.Remove(staging)
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return fmt.Errorf("cannot install new binary at %s: %w", dst, err)
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}
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return nil
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}
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func copyFile(src, dst string) error {
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in, err := os.Open(src)
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if err != nil {
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return fmt.Errorf("cannot open %s: %w", src, err)
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}
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defer func() { _ = in.Close() }()
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if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
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return fmt.Errorf("cannot ensure %s: %w", filepath.Dir(dst), err)
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}
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out, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o755)
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if err != nil {
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return fmt.Errorf("cannot create %s: %w", dst, err)
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}
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if _, err := io.Copy(out, in); err != nil {
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_ = out.Close()
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_ = os.Remove(dst)
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return fmt.Errorf("cannot copy to %s: %w", dst, err)
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}
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if err := out.Sync(); err != nil {
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_ = out.Close()
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_ = os.Remove(dst)
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return fmt.Errorf("cannot fsync %s: %w", dst, err)
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}
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if err := out.Close(); err != nil {
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_ = os.Remove(dst)
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return fmt.Errorf("cannot close %s: %w", dst, err)
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}
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return nil
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}
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// CleanupAfterRestart removes the previous-version binary left behind
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// by replaceBinary. Best-effort: callers ignore errors, so a still-locked
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// `<exePath>.old` is fine and will be retried on the next boot.
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func CleanupAfterRestart(exePath string) {
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if exePath == "" {
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return
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}
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_ = os.Remove(exePath + oldSuffix)
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}
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