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wgengine/router: use better NetworkManager API

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Signed-off-by: Dmytro Shynkevych <dmytro@tailscale.com>
main
Dmytro Shynkevych 6 years ago committed by Dmytro Shynkevych
parent 5df6be9d38
commit a3e7252ce6
2 changed files with 47 additions and 58 deletions
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  1. 100
      wgengine/router/dns_networkmanager.go
  2. 5
      wgengine/router/dns_resolved.go

100
wgengine/router/dns_networkmanager.go
Unescape View File

@ -18,7 +18,7 @@ import (
"github.com/godbus/dbus/v5"
)
type nmSettings map[string]map[string]dbus.Variant
type nmConnectionSettings map[string]map[string]dbus.Variant
// nmIsActive determines if NetworkManager is currently managing system DNS settings.
func nmIsActive() bool {
@ -56,23 +56,28 @@ func dnsNetworkManagerUp(config DNSConfig, interfaceName string) error {
ctx, cancel := context.WithTimeout(context.Background(), dnsReconfigTimeout)
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)
}
defer conn.Close()
// This is how we get at the DNS settings:
//
// org.freedesktop.NetworkManager
// ⇩
// org.freedesktop.NetworkManager.Device
// (describes a network interface)
// ⇩
// org.freedesktop.NetworkManager.Connection.Active
// (active instance of a connection initialized from settings)
// ⇩
// org.freedesktop.NetworkManager.Connection
// (connection settings)
// |
// [GetDeviceByIpIface]
// |
// v
// org.freedesktop.NetworkManager.Device <--------\
// (describes a network interface) |
// | |
// [GetAppliedConnection] [Reapply]
// | |
// v |
// org.freedesktop.NetworkManager.Connection |
// (connection settings) ------/
// contains {dns, dns-priority, dns-search}
//
// Ref: https://developer.gnome.org/NetworkManager/stable/settings-ipv4.html.
@ -88,49 +93,20 @@ func dnsNetworkManagerUp(config DNSConfig, interfaceName string) error {
interfaceName,
).Store(&devicePath)
if err != nil {
return fmt.Errorf("GetDeviceByIpIface: %w", err)
return fmt.Errorf("getDeviceByIpIface: %w", err)
}
device := conn.Object("org.freedesktop.NetworkManager", devicePath)
var activeConnPath dbus.ObjectPath
var (
settings nmConnectionSettings
version uint64
)
err = device.CallWithContext(
ctx, "org.freedesktop.DBus.Properties.Get", 0,
"org.freedesktop.NetworkManager.Device", "ActiveConnection",
).Store(&activeConnPath)
if err != nil {
return fmt.Errorf("getting ActiveConnection: %w", err)
}
activeConn := conn.Object("org.freedesktop.NetworkManager", activeConnPath)
var connPath dbus.ObjectPath
err = activeConn.CallWithContext(
ctx, "org.freedesktop.DBus.Properties.Get", 0,
"org.freedesktop.NetworkManager.Connection.Active", "Connection",
).Store(&connPath)
ctx, "org.freedesktop.NetworkManager.Device.GetAppliedConnection", 0,
uint32(0),
).Store(&settings, &version)
if err != nil {
return fmt.Errorf("getting Connection: %w", err)
}
connection := conn.Object("org.freedesktop.NetworkManager", connPath)
// Note: strictly speaking, the following is not safe.
//
// It appears that the way to update connection settings
// in NetworkManager is to get an entire connection settings object,
// modify the fields we are interested in, then submit the modified object.
//
// This is unfortunate: if the network state changes in the meantime
// (most relevantly to us, if routes change), we will overwrite those changes.
//
// That said, fortunately, this should have no real effect, as Tailscale routes
// do not seem to show up in NetworkManager at all,
// so they are presumably immune from being tampered with.
var settings nmSettings
err = connection.CallWithContext(
ctx, "org.freedesktop.NetworkManager.Settings.Connection.GetSettings", 0,
).Store(&settings)
if err != nil {
return fmt.Errorf("getting Settings: %w", err)
return fmt.Errorf("getAppliedConnection: %w", err)
}
// Frustratingly, NetworkManager represents IPv4 addresses as uint32s,
@ -152,10 +128,15 @@ func dnsNetworkManagerUp(config DNSConfig, interfaceName string) error {
ipv4Map := settings["ipv4"]
ipv4Map["dns"] = dbus.MakeVariant(dnsv4)
ipv4Map["dns-search"] = dbus.MakeVariant(config.Domains)
// dns-priority = -1 ensures that we have priority
// over other interfaces, except those exploiting this same trick.
// Ref: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1211110/comments/92.
ipv4Map["dns-priority"] = dbus.MakeVariant(-1)
// We should only request priority if we have nameservers to set.
if len(dnsv4) == 0 {
ipv4Map["dns-priority"] = dbus.MakeVariant(100)
} else {
// dns-priority = -1 ensures that we have priority
// over other interfaces, except those exploiting this same trick.
// Ref: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1211110/comments/92.
ipv4Map["dns-priority"] = dbus.MakeVariant(-1)
}
// In principle, we should not need set this to true,
// as our interface does not configure any automatic DNS settings (presumably via DHCP).
// All the same, better to be safe.
@ -175,7 +156,11 @@ func dnsNetworkManagerUp(config DNSConfig, interfaceName string) error {
// Finally, set the actual DNS config.
ipv6Map["dns"] = dbus.MakeVariant(dnsv6)
ipv6Map["dns-search"] = dbus.MakeVariant(config.Domains)
ipv6Map["dns-priority"] = dbus.MakeVariant(-1)
if len(dnsv6) == 0 {
ipv6Map["dns-priority"] = dbus.MakeVariant(100)
} else {
ipv6Map["dns-priority"] = dbus.MakeVariant(-1)
}
ipv6Map["ignore-auto-dns"] = dbus.MakeVariant(true)
// deprecatedProperties are the properties in interface settings
@ -193,11 +178,12 @@ func dnsNetworkManagerUp(config DNSConfig, interfaceName string) error {
delete(ipv6Map, property)
}
err = connection.CallWithContext(
ctx, "org.freedesktop.NetworkManager.Settings.Connection.UpdateUnsaved", 0, settings,
err = device.CallWithContext(
ctx, "org.freedesktop.NetworkManager.Device.Reapply", 0,
settings, version, uint32(0),
).Store()
if err != nil {
return fmt.Errorf("setting Settings: %w", err)
return fmt.Errorf("reapply: %w", err)
}
return nil

5
wgengine/router/dns_resolved.go
Unescape View File

@ -88,11 +88,12 @@ func dnsResolvedUp(config DNSConfig) error {
ctx, cancel := context.WithTimeout(context.Background(), dnsReconfigTimeout)
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)
}
defer conn.Close()
resolved := conn.Object(
"org.freedesktop.resolve1",
@ -155,6 +156,8 @@ func dnsResolvedDown() error {
ctx, cancel := context.WithTimeout(context.Background(), dnsReconfigTimeout)
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)

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