mirror of
https://github.com/Control-D-Inc/ctrld.git
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3e388c2857
So it would work in more general case than just captive portal network, which ctrld have supported recently. Uses who may want no leaking behavior can use a config to turn off this feature.
74 lines
2.2 KiB
Go
74 lines
2.2 KiB
Go
package cli
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import (
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"net"
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"net/netip"
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"path/filepath"
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"github.com/fsnotify/fsnotify"
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)
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// watchResolvConf watches any changes to /etc/resolv.conf file,
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// and reverting to the original config set by ctrld.
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func (p *prog) watchResolvConf(iface *net.Interface, ns []netip.Addr, setDnsFn func(iface *net.Interface, ns []netip.Addr) error) {
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resolvConfPath := "/etc/resolv.conf"
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// Evaluating symbolics link to watch the target file that /etc/resolv.conf point to.
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if rp, _ := filepath.EvalSymlinks(resolvConfPath); rp != "" {
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resolvConfPath = rp
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}
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mainLog.Load().Debug().Msgf("start watching %s file", resolvConfPath)
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watcher, err := fsnotify.NewWatcher()
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if err != nil {
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mainLog.Load().Warn().Err(err).Msg("could not create watcher for /etc/resolv.conf")
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return
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}
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defer watcher.Close()
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// We watch /etc instead of /etc/resolv.conf directly,
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// see: https://github.com/fsnotify/fsnotify#watching-a-file-doesnt-work-well
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watchDir := filepath.Dir(resolvConfPath)
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if err := watcher.Add(watchDir); err != nil {
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mainLog.Load().Warn().Err(err).Msgf("could not add %s to watcher list", watchDir)
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return
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}
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for {
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select {
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case <-p.dnsWatcherStopCh:
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return
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case <-p.stopCh:
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mainLog.Load().Debug().Msgf("stopping watcher for %s", resolvConfPath)
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return
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case event, ok := <-watcher.Events:
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if p.leakingQuery.Load() {
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return
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}
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if !ok {
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return
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}
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if event.Name != resolvConfPath { // skip if not /etc/resolv.conf changes.
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continue
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}
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if event.Has(fsnotify.Write) || event.Has(fsnotify.Create) {
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mainLog.Load().Debug().Msg("/etc/resolv.conf changes detected, reverting to ctrld setting")
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if err := watcher.Remove(watchDir); err != nil {
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mainLog.Load().Error().Err(err).Msg("failed to pause watcher")
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continue
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}
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if err := setDnsFn(iface, ns); err != nil {
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mainLog.Load().Error().Err(err).Msg("failed to revert /etc/resolv.conf changes")
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}
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if err := watcher.Add(watchDir); err != nil {
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mainLog.Load().Error().Err(err).Msg("failed to continue running watcher")
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return
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}
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}
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case err, ok := <-watcher.Errors:
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if !ok {
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return
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}
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mainLog.Load().Err(err).Msg("could not get event for /etc/resolv.conf")
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}
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}
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}
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