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net/dns: refactor dbus connection setup in resolved manager.

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Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson 2021-04-12 18:03:34 -07:00
parent 2df6372b67
commit fe3b1ab747
1 changed files with 25 additions and 46 deletions
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71
net/dns/resolved.go
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@ -84,32 +84,27 @@ func isResolvedActive() bool {
// resolvedManager uses the systemd-resolved DBus API. // resolvedManager uses the systemd-resolved DBus API.
type resolvedManager struct { type resolvedManager struct {
logf logger.Logf logf logger.Logf
resolved dbus.BusObject
} }
func newResolvedManager(logf logger.Logf) (resolvedManager, error) { func newResolvedManager(logf logger.Logf) (*resolvedManager, error) {
return resolvedManager{ conn, err := dbus.SystemBus()
logf: logf, if err != nil {
return nil, err
}
return &resolvedManager{
logf: logf,
resolved: conn.Object("org.freedesktop.resolve1", dbus.ObjectPath("/org/freedesktop/resolve1")),
}, nil }, nil
} }
// Up implements managerImpl. // Up implements managerImpl.
func (m resolvedManager) SetDNS(config OSConfig) error { func (m *resolvedManager) SetDNS(config OSConfig) error {
ctx, cancel := context.WithTimeout(context.Background(), reconfigTimeout) ctx, cancel := context.WithTimeout(context.Background(), reconfigTimeout)
defer cancel() defer cancel()
// conn is a shared connection whose lifecycle is managed by the dbus package.
// We should not interfere with that by closing it.
conn, err := dbus.SystemBus()
if err != nil {
return fmt.Errorf("connecting to system bus: %w", err)
}
resolved := conn.Object(
"org.freedesktop.resolve1",
dbus.ObjectPath("/org/freedesktop/resolve1"),
)
// In principle, we could persist this in the manager struct // In principle, we could persist this in the manager struct
// if we knew that interface indices are persistent. This does not seem to be the case. // if we knew that interface indices are persistent. This does not seem to be the case.
_, iface, err := interfaces.Tailscale() _, iface, err := interfaces.Tailscale()
@ -136,7 +131,7 @@ func (m resolvedManager) SetDNS(config OSConfig) error {
} }
} }
err = resolved.CallWithContext( err = m.resolved.CallWithContext(
ctx, "org.freedesktop.resolve1.Manager.SetLinkDNS", 0, ctx, "org.freedesktop.resolve1.Manager.SetLinkDNS", 0,
iface.Index, linkNameservers, iface.Index, linkNameservers,
).Store() ).Store()
@ -177,7 +172,7 @@ func (m resolvedManager) SetDNS(config OSConfig) error {
}) })
} }
err = resolved.CallWithContext( err = m.resolved.CallWithContext(
ctx, "org.freedesktop.resolve1.Manager.SetLinkDomains", 0, ctx, "org.freedesktop.resolve1.Manager.SetLinkDomains", 0,
iface.Index, linkDomains, iface.Index, linkDomains,
).Store() ).Store()
@ -185,7 +180,7 @@ func (m resolvedManager) SetDNS(config OSConfig) error {
return fmt.Errorf("setLinkDomains: %w", err) return fmt.Errorf("setLinkDomains: %w", err)
} }
if call := resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkDefaultRoute", 0, iface.Index, len(config.MatchDomains) == 0); call.Err != nil { if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkDefaultRoute", 0, iface.Index, len(config.MatchDomains) == 0); call.Err != nil {
return fmt.Errorf("setLinkDefaultRoute: %w", err) return fmt.Errorf("setLinkDefaultRoute: %w", err)
} }
@ -194,56 +189,44 @@ func (m resolvedManager) SetDNS(config OSConfig) error {
// or something). // or something).
// Disable LLMNR, we don't do multicast. // Disable LLMNR, we don't do multicast.
if call := resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkLLMNR", 0, iface.Index, "no"); call.Err != nil { if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkLLMNR", 0, iface.Index, "no"); call.Err != nil {
m.logf("[v1] failed to disable LLMNR: %v", call.Err) m.logf("[v1] failed to disable LLMNR: %v", call.Err)
} }
// Disable mdns. // Disable mdns.
if call := resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkMulticastDNS", 0, iface.Index, "no"); call.Err != nil { if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkMulticastDNS", 0, iface.Index, "no"); call.Err != nil {
m.logf("[v1] failed to disable mdns: %v", call.Err) m.logf("[v1] failed to disable mdns: %v", call.Err)
} }
// We don't support dnssec consistently right now, force it off to // We don't support dnssec consistently right now, force it off to
// avoid partial failures when we split DNS internally. // avoid partial failures when we split DNS internally.
if call := resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkDNSSEC", 0, iface.Index, "no"); call.Err != nil { if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkDNSSEC", 0, iface.Index, "no"); call.Err != nil {
m.logf("[v1] failed to disable DNSSEC: %v", call.Err) m.logf("[v1] failed to disable DNSSEC: %v", call.Err)
} }
if call := resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkDNSOverTLS", 0, iface.Index, "no"); call.Err != nil { if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.SetLinkDNSOverTLS", 0, iface.Index, "no"); call.Err != nil {
m.logf("[v1] failed to disable DoT: %v", call.Err) m.logf("[v1] failed to disable DoT: %v", call.Err)
} }
if call := resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.FlushCaches", 0); call.Err != nil { if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.FlushCaches", 0); call.Err != nil {
m.logf("failed to flush resolved DNS cache: %v", call.Err) m.logf("failed to flush resolved DNS cache: %v", call.Err)
} }
return nil return nil
} }
func (m resolvedManager) SupportsSplitDNS() bool { func (m *resolvedManager) SupportsSplitDNS() bool {
return true return true
} }
func (m resolvedManager) GetBaseConfig() (OSConfig, error) { func (m *resolvedManager) GetBaseConfig() (OSConfig, error) {
return OSConfig{}, ErrGetBaseConfigNotSupported return OSConfig{}, ErrGetBaseConfigNotSupported
} }
func (m resolvedManager) Close() error { func (m *resolvedManager) Close() error {
ctx, cancel := context.WithTimeout(context.Background(), reconfigTimeout) ctx, cancel := context.WithTimeout(context.Background(), reconfigTimeout)
defer cancel() defer cancel()
// conn is a shared connection whose lifecycle is managed by the dbus package.
// We should not interfere with that by closing it.
conn, err := dbus.SystemBus()
if err != nil {
return fmt.Errorf("connecting to system bus: %w", err)
}
resolved := conn.Object(
"org.freedesktop.resolve1",
dbus.ObjectPath("/org/freedesktop/resolve1"),
)
_, iface, err := interfaces.Tailscale() _, iface, err := interfaces.Tailscale()
if err != nil { if err != nil {
return fmt.Errorf("getting interface index: %w", err) return fmt.Errorf("getting interface index: %w", err)
@ -252,12 +235,8 @@ func (m resolvedManager) Close() error {
return errNotReady return errNotReady
} }
err = resolved.CallWithContext( if call := m.resolved.CallWithContext(ctx, "org.freedesktop.resolve1.Manager.RevertLink", 0, iface.Index); call.Err != nil {
ctx, "org.freedesktop.resolve1.Manager.RevertLink", 0, return fmt.Errorf("RevertLink: %w", call.Err)
iface.Index,
).Store()
if err != nil {
return fmt.Errorf("RevertLink: %w", err)
} }
return nil return nil