mirror of
https://github.com/mjl-/mox.git
synced 2025-07-10 06:34:40 +03:00
change mox to start as root, bind to network sockets, then drop to regular unprivileged mox user
makes it easier to run on bsd's, where you cannot (easily?) let non-root users
bind to ports <1024. starting as root also paves the way for future improvements
with privilege separation.
unfortunately, this requires changes to how you start mox. though mox will help
by automatically fix up dir/file permissions/ownership.
if you start mox from the systemd unit file, you should update it so it starts
as root and adds a few additional capabilities:
# first update the mox binary, then, as root:
./mox config printservice >mox.service
systemctl daemon-reload
systemctl restart mox
journalctl -f -u mox &
# you should see mox start up, with messages about fixing permissions on dirs/files.
if you used the recommended config/ and data/ directory, in a directory just for
mox, and with the mox user called "mox", this should be enough.
if you don't want mox to modify dir/file permissions, set "NoFixPermissions:
true" in mox.conf.
if you named the mox user something else than mox, e.g. "_mox", add "User: _mox"
to mox.conf.
if you created a shared service user as originally suggested, you may want to
get rid of that as it is no longer useful and may get in the way. e.g. if you
had /home/service/mox with a "service" user, that service user can no longer
access any files: only mox and root can.
this also adds scripts for building mox docker images for alpine-supported
platforms.
the "restart" subcommand has been removed. it wasn't all that useful and got in
the way.
and another change: when adding a domain while mtasts isn't enabled, don't add
the per-domain mtasts config, as it would cause failure to add the domain.
based on report from setting up mox on openbsd from mteege.
and based on issue #3. thanks for the feedback!
This commit is contained in:
Mechiel Lukkien
339
serve.go
339
serve.go
@ -4,12 +4,13 @@ import (
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"context"
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cryptorand "crypto/rand"
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"fmt"
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"io/fs"
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"net"
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"os"
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"os/signal"
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"path/filepath"
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"runtime"
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"runtime/debug"
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"strconv"
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"strings"
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"sync"
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"syscall"
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@ -24,7 +25,6 @@ import (
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"github.com/mjl-/mox/metrics"
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"github.com/mjl-/mox/mlog"
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"github.com/mjl-/mox/mox-"
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"github.com/mjl-/mox/moxio"
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"github.com/mjl-/mox/moxvar"
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"github.com/mjl-/mox/store"
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"github.com/mjl-/mox/updates"
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@ -138,60 +138,75 @@ requested, other TLS certificates are requested on demand.
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log := mlog.New("serve")
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if os.Getuid() == 0 {
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log.Fatal("refusing to run as root, please start mox as unprivileged user")
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}
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// No need to potentially start and keep multiple processes. As root, we just need
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// to start the child process.
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runtime.GOMAXPROCS(1)
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if fds := os.Getenv("MOX_RESTART_CTL_SOCKET"); fds != "" {
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log.Print("restarted")
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fd, err := strconv.ParseUint(fds, 10, 32)
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if err != nil {
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log.Fatalx("restart with invalid ctl socket", err, mlog.Field("fd", fds))
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log.Print("starting as root, initializing network listeners", mlog.Field("version", moxvar.Version), mlog.Field("pid", os.Getpid()))
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if os.Getenv("MOX_SOCKETS") != "" {
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log.Fatal("refusing to start as root with $MOX_SOCKETS set")
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}
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f := os.NewFile(uintptr(fd), "restartctl")
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if _, err := fmt.Fprint(f, "ok\n"); err != nil {
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log.Infox("writing ok to restart ctl socket", err)
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}
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err = f.Close()
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log.Check(err, "closing restart ctl socket")
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}
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log.Print("starting up", mlog.Field("version", moxvar.Version))
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shutdown := func() {
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// We indicate we are shutting down. Causes new connections and new SMTP commands
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// to be rejected. Should stop active connections pretty quickly.
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mox.ShutdownCancel()
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// Now we are going to wait for all connections to be gone, up to a timeout.
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done := mox.Connections.Done()
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second := time.Tick(time.Second)
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select {
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case <-done:
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log.Print("connections shutdown, waiting until 1 second passed")
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<-second
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case <-time.Tick(3 * time.Second):
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// We now cancel all pending operations, and set an immediate deadline on sockets.
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// Should get us a clean shutdown relatively quickly.
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mox.ContextCancel()
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mox.Connections.Shutdown()
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second := time.Tick(time.Second)
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select {
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case <-done:
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log.Print("no more connections, shutdown is clean, waiting until 1 second passed")
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<-second // Still wait for second, giving processes like imports a chance to clean up.
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case <-second:
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log.Print("shutting down with pending sockets")
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if !mox.Conf.Static.NoFixPermissions {
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// Fix permissions now that we have privilege to do so. Useful for update of v0.0.1
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// that was running directly as mox-user.
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workdir, err := os.Getwd()
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if err != nil {
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log.Printx("get working dir, continuing without potentially fixing up permissions", err)
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} else {
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configdir := filepath.Dir(mox.ConfigStaticPath)
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datadir := mox.DataDirPath(".")
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err := fixperms(log, workdir, configdir, datadir, mox.Conf.Static.UID, mox.Conf.Static.GID)
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if err != nil {
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log.Fatalx("fixing permissions", err)
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}
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}
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}
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err := os.Remove(mox.DataDirPath("ctl"))
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log.Check(err, "removing ctl unix domain socket during shutdown")
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} else {
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log.Print("starting as unprivileged user", mlog.Field("user", mox.Conf.Static.User), mlog.Field("uid", mox.Conf.Static.UID), mlog.Field("gid", mox.Conf.Static.GID), mlog.Field("pid", os.Getpid()))
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mox.RestorePassedSockets()
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}
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if err := moxio.CheckUmask(); err != nil {
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log.Errorx("bad umask", err)
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syscall.Umask(syscall.Umask(007) | 007)
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// Initialize key and random buffer for creating opaque SMTP
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// transaction IDs based on "cid"s.
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recvidpath := mox.DataDirPath("receivedid.key")
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recvidbuf, err := os.ReadFile(recvidpath)
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if err != nil || len(recvidbuf) != 16+8 {
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recvidbuf = make([]byte, 16+8)
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if _, err := cryptorand.Read(recvidbuf); err != nil {
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log.Fatalx("reading random recvid data", err)
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}
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if err := os.WriteFile(recvidpath, recvidbuf, 0660); err != nil {
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log.Fatalx("writing recvidpath", err, mlog.Field("path", recvidpath))
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}
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err := os.Chown(recvidpath, int(mox.Conf.Static.UID), 0)
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log.Check(err, "chown receveidid.key", mlog.Field("path", recvidpath), mlog.Field("uid", mox.Conf.Static.UID), mlog.Field("gid", 0))
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err = os.Chmod(recvidpath, 0640)
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log.Check(err, "chmod receveidid.key to 0640", mlog.Field("path", recvidpath))
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}
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if err := mox.ReceivedIDInit(recvidbuf[:16], recvidbuf[16:]); err != nil {
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log.Fatalx("init receivedid", err)
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}
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// Start mox. If running as root, this will bind/listen on network sockets, and
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// fork and exec itself as unprivileged user, then waits for the child to stop and
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// exit. When running as root, this function never returns. But the new
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// unprivileged user will get here again, with network sockets prepared.
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//
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// We listen to the unix domain ctl socket afterwards, which we always remove
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// before listening. We need to do that because we may not have cleaned up our
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// control socket during unexpected shutdown. We don't want to remove and listen on
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// the unix domain socket first. If we would, we would make the existing instance
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// unreachable over its ctl socket, and then fail because the network addresses are
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// taken.
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const mtastsdbRefresher = true
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const skipForkExec = false
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if err := start(mtastsdbRefresher, skipForkExec); err != nil {
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log.Fatalx("start", err)
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}
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log.Print("ready to serve")
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if mox.Conf.Static.CheckUpdates {
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checkUpdates := func() time.Duration {
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@ -281,37 +296,40 @@ requested, other TLS certificates are requested on demand.
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}()
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}
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// Initialize key and random buffer for creating opaque SMTP
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// transaction IDs based on "cid"s.
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recvidpath := mox.DataDirPath("receivedid.key")
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recvidbuf, err := os.ReadFile(recvidpath)
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if err != nil || len(recvidbuf) != 16+8 {
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recvidbuf = make([]byte, 16+8)
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if _, err := cryptorand.Read(recvidbuf); err != nil {
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log.Fatalx("reading random recvid data", err)
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}
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if err := os.WriteFile(recvidpath, recvidbuf, 0660); err != nil {
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log.Fatalx("writing recvidpath", err, mlog.Field("path", recvidpath))
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}
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}
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if err := mox.ReceivedIDInit(recvidbuf[:16], recvidbuf[16:]); err != nil {
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log.Fatalx("init receivedid", err)
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}
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// We start the network listeners first. If an instance is already running, we'll
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// get errors about address being in use. We listen to the unix domain socket
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// afterwards, which we always remove before listening. We need to do that because
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// we may not have cleaned up our control socket during unexpected shutdown. We
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// don't want to remove and listen on the unix domain socket first. If we would, we
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// would make the existing instance unreachable over its ctl socket, and then fail
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// because the network addresses are taken.
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mtastsdbRefresher := true
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if err := start(mtastsdbRefresher); err != nil {
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log.Fatalx("start", err)
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}
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go monitorDNSBL(log)
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shutdown := func() {
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// We indicate we are shutting down. Causes new connections and new SMTP commands
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// to be rejected. Should stop active connections pretty quickly.
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mox.ShutdownCancel()
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// Now we are going to wait for all connections to be gone, up to a timeout.
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done := mox.Connections.Done()
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second := time.Tick(time.Second)
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select {
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case <-done:
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log.Print("connections shutdown, waiting until 1 second passed")
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<-second
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case <-time.Tick(3 * time.Second):
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// We now cancel all pending operations, and set an immediate deadline on sockets.
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// Should get us a clean shutdown relatively quickly.
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mox.ContextCancel()
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mox.Connections.Shutdown()
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second := time.Tick(time.Second)
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select {
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case <-done:
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log.Print("no more connections, shutdown is clean, waiting until 1 second passed")
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<-second // Still wait for second, giving processes like imports a chance to clean up.
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case <-second:
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log.Print("shutting down with pending sockets")
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}
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}
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err := os.Remove(mox.DataDirPath("ctl"))
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log.Check(err, "removing ctl unix domain socket during shutdown")
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}
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ctlpath := mox.DataDirPath("ctl")
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_ = os.Remove(ctlpath)
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ctl, err := net.Listen("unix", ctlpath)
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@ -359,4 +377,171 @@ requested, other TLS certificates are requested on demand.
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sig := <-sigc
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log.Print("shutting down, waiting max 3s for existing connections", mlog.Field("signal", sig))
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shutdown()
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if num, ok := sig.(syscall.Signal); ok {
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os.Exit(int(num))
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} else {
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os.Exit(1)
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}
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}
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// Set correct permissions for mox working directory, binary, config and data and service file.
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//
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// We require being able to stat the basic non-optional paths. Then we'll try to
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// fix up permissions. If an error occurs when fixing permissions, we log and
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// continue (could not be an actual problem).
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func fixperms(log *mlog.Log, workdir, configdir, datadir string, moxuid, moxgid uint32) (rerr error) {
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type fserr struct{ Err error }
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defer func() {
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x := recover()
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if x == nil {
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return
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}
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e, ok := x.(fserr)
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if ok {
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rerr = e.Err
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} else {
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panic(x)
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}
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}()
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checkf := func(err error, format string, args ...any) {
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if err != nil {
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panic(fserr{fmt.Errorf(format, args...)})
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}
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}
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// Changes we have to make. We collect them first, then apply.
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type change struct {
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path string
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uid, gid *uint32
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olduid, oldgid uint32
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mode *fs.FileMode
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oldmode fs.FileMode
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}
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var changes []change
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ensure := func(p string, uid, gid uint32, perm fs.FileMode) bool {
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fi, err := os.Stat(p)
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checkf(err, "stat %s", p)
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st, ok := fi.Sys().(*syscall.Stat_t)
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if !ok {
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checkf(fmt.Errorf("got %T", st), "stat sys, expected syscall.Stat_t")
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}
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var ch change
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if st.Uid != uid || st.Gid != gid {
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ch.uid = &uid
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ch.gid = &gid
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ch.olduid = st.Uid
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ch.oldgid = st.Gid
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}
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if perm != fi.Mode()&(fs.ModeSetgid|0777) {
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ch.mode = &perm
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ch.oldmode = fi.Mode() & (fs.ModeSetgid | 0777)
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}
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var zerochange change
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if ch == zerochange {
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return false
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}
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ch.path = p
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changes = append(changes, ch)
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return true
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}
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xexists := func(p string) bool {
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_, err := os.Stat(p)
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if err != nil && !os.IsNotExist(err) {
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checkf(err, "stat %s", p)
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}
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return err == nil
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}
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// We ensure these permissions:
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//
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// $workdir root:mox 0751
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// $configdir mox:root 0750 + setgid, and recursively (but files 0640)
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// $datadir mox:root 0750 + setgid, and recursively (but files 0640)
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// $workdir/mox (binary, optional) root:mox 0750
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// $workdir/mox.service (systemd service file, optional) root:root 0644
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const root = 0
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ensure(workdir, root, moxgid, 0751)
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fixconfig := ensure(configdir, moxuid, 0, fs.ModeSetgid|0750)
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fixdata := ensure(datadir, moxuid, 0, fs.ModeSetgid|0750)
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// Binary and systemd service file do not exist (there) when running under docker.
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binary := filepath.Join(workdir, "mox")
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if xexists(binary) {
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ensure(binary, root, moxgid, 0750)
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}
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svc := filepath.Join(workdir, "mox.service")
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if xexists(svc) {
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ensure(svc, root, root, 0644)
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}
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if len(changes) == 0 {
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return
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}
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// Apply changes.
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log.Print("fixing up permissions, will continue on errors")
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for _, ch := range changes {
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if ch.uid != nil {
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err := os.Chown(ch.path, int(*ch.uid), int(*ch.gid))
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log.Printx("chown, fixing uid/gid", err, mlog.Field("path", ch.path), mlog.Field("olduid", ch.olduid), mlog.Field("oldgid", ch.oldgid), mlog.Field("newuid", *ch.uid), mlog.Field("newgid", *ch.gid))
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}
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if ch.mode != nil {
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err := os.Chmod(ch.path, *ch.mode)
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log.Printx("chmod, fixing permissions", err, mlog.Field("path", ch.path), mlog.Field("oldmode", fmt.Sprintf("%03o", ch.oldmode)), mlog.Field("newmode", fmt.Sprintf("%03o", *ch.mode)))
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}
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}
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walkchange := func(dir string) {
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err := filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
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if err != nil {
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log.Printx("walk error, continuing", err, mlog.Field("path", path))
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return nil
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}
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fi, err := d.Info()
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if err != nil {
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log.Printx("stat during walk, continuing", err, mlog.Field("path", path))
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return nil
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}
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st, ok := fi.Sys().(*syscall.Stat_t)
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if !ok {
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log.Printx("syscall stat during walk, continuing", err, mlog.Field("path", path))
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return nil
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}
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if st.Uid != moxuid || st.Gid != root {
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err := os.Chown(path, int(moxuid), root)
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log.Printx("walk chown, fixing uid/gid", err, mlog.Field("path", path), mlog.Field("olduid", st.Uid), mlog.Field("oldgid", st.Gid), mlog.Field("newuid", moxuid), mlog.Field("newgid", root))
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}
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omode := fi.Mode() & (fs.ModeSetgid | 0777)
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var nmode fs.FileMode
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if fi.IsDir() {
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nmode = fs.ModeSetgid | 0750
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} else {
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nmode = 0640
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}
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if omode != nmode {
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err := os.Chmod(path, nmode)
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log.Printx("walk chmod, fixing permissions", err, mlog.Field("path", path), mlog.Field("oldmode", fmt.Sprintf("%03o", omode)), mlog.Field("newmode", fmt.Sprintf("%03o", nmode)))
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}
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return nil
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})
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log.Check(err, "walking dir to fix permissions", mlog.Field("dir", dir))
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}
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// If config or data dir needed fixing, also set uid/gid and mode and files/dirs
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// inside, recursively. We don't always recurse, data probably contains many files.
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if fixconfig {
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log.Print("fixing permissions in config dir", mlog.Field("configdir", configdir))
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walkchange(configdir)
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}
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if fixdata {
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log.Print("fixing permissions in data dir", mlog.Field("configdir", configdir))
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walkchange(datadir)
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}
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return nil
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}
|
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Reference in New Issue
Block a user