Add support for IPv6 networks (on Linux clients) (#1459)

* Feat add basic support for IPv6 networks

Newly generated networks automatically generate an IPv6 prefix of size
64 within the ULA address range, devices obtain a randomly generated
address within this prefix.

Currently, this is Linux only and does not yet support all features
(routes currently cause an error).

* Fix firewall configuration for IPv6 networks

* Fix routing configuration for IPv6 networks

* Feat provide info on IPv6 support for specific client to mgmt server

* Feat allow configuration of IPv6 support through API, improve stability

* Feat add IPv6 support to new firewall implementation

* Fix peer list item response not containing IPv6 address

* Fix nftables breaking on IPv6 address change

* Fix build issues for non-linux systems

* Fix intermittent disconnections when IPv6 is enabled

* Fix test issues and make some minor revisions

* Fix some more testing issues

* Fix more CI issues due to IPv6

* Fix more testing issues

* Add inheritance of IPv6 enablement status from groups

* Fix IPv6 events not having associated messages

* Address first review comments regarding IPv6 support

* Fix IPv6 table being created even when IPv6 is disabled

Also improved stability of IPv6 route and firewall handling on client side

* Fix IPv6 routes not being removed

* Fix DNS IPv6 issues, limit IPv6 nameservers to IPv6 peers

* Improve code for IPv6 DNS server selection, add AAAA custom records

* Ensure IPv6 routes can only exist for IPv6 routing peers

* Fix IPv6 network generation randomness

* Fix a bunch of compilation issues and test failures

* Replace method calls that are unavailable in Go 1.21

* Fix nil dereference in cleanUpDefaultForwardRules6

* Fix nil pointer dereference when persisting IPv6 network in sqlite

* Clean up of client-side code changes for IPv6

* Fix nil dereference in rule mangling and compilation issues

* Add a bunch of client-side test cases for IPv6

* Fix IPv6 tests running on unsupported environments

* Fix import cycle in tests

* Add missing method SupportsIPv6() for windows

* Require IPv6 default route for IPv6 tests

* Fix panics in routemanager tests on non-linux

* Fix some more route manager tests concerning IPv6

* Add some final client-side tests

* Add IPv6 tests for management code, small fixes

* Fix linting issues

* Fix small test suite issues

* Fix linter issues and builds on macOS and Windows again

* fix builds for iOS because of IPv6 breakage

management/server/peer_test.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"github.com/stretchr/testify/require"
 	"testing"
 	"time"
 
@@ -136,6 +137,112 @@ func TestAccountManager_GetNetworkMap(t *testing.T) {
 	}
 }
 
+func TestDefaultAccountManager_DeterminePeerV6(t *testing.T) {
+	manager, err := createManager(t)
+	if err != nil {
+		t.Fatal(err)
+		return
+	}
+
+	expectedId := "test_account"
+	userId := "account_creator"
+	account, err := createAccount(manager, expectedId, userId, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	setupKey, err := manager.CreateSetupKey(account.Id, "test-key", SetupKeyReusable, time.Hour, nil, 999, userId, false)
+	if err != nil {
+		t.Fatal("error creating setup key")
+		return
+	}
+
+	peerKey1, err := wgtypes.GeneratePrivateKey()
+	if err != nil {
+		t.Fatal(err)
+		return
+	}
+
+	peer1, _, err := manager.AddPeer(setupKey.Key, "", &nbpeer.Peer{
+		Key: peerKey1.PublicKey().String(),
+		Meta: nbpeer.PeerSystemMeta{
+			Hostname:      "test-peer-1",
+			Ipv6Supported: true,
+		},
+	})
+	if err != nil {
+		t.Errorf("expecting peer to be added, got failure %v", err)
+		return
+	}
+
+	peerKey2, err := wgtypes.GeneratePrivateKey()
+	if err != nil {
+		t.Fatal(err)
+		return
+	}
+
+	peer2, _, err := manager.AddPeer(setupKey.Key, "", &nbpeer.Peer{
+		Key: peerKey2.PublicKey().String(),
+		Meta: nbpeer.PeerSystemMeta{
+			Hostname:      "test-peer-2",
+			Ipv6Supported: false,
+		},
+	})
+
+	if err != nil {
+		t.Errorf("expecting peer to be added, got failure %v", err)
+		return
+	}
+
+	account, err = manager.Store.GetAccount(account.Id)
+	require.NoError(t, err, "unable to fetch updated account")
+
+	// Check if automatic setting defaults to "false".
+	// (Other tests for interactions between the automatic setting and group/route memberships are already covered in
+	// group_test.go and route_test.go)
+	_, err = manager.DeterminePeerV6(account, peer1)
+	require.NoError(t, err, "unable to determine effective peer IPv6 status")
+	_, err = manager.DeterminePeerV6(account, peer2)
+	require.NoError(t, err, "unable to determine effective peer IPv6 status")
+	require.Nil(t, peer1.IP6, "peer1 IPv6 address did not default to nil.")
+	require.Nil(t, peer1.IP6, "peer2 IPv6 address did not default to nil.")
+
+	peer1.V6Setting = nbpeer.V6Disabled
+	peer2.V6Setting = nbpeer.V6Disabled
+	_, err = manager.DeterminePeerV6(account, peer1)
+	require.NoError(t, err, "unable to determine effective peer IPv6 status")
+	_, err = manager.DeterminePeerV6(account, peer2)
+	require.NoError(t, err, "unable to determine effective peer IPv6 status")
+	require.Nil(t, peer1.IP6, "peer1 IPv6 address is not nil even though it is force disabled.")
+	require.Nil(t, peer2.IP6, "peer2 IPv6 address is not nil even though it is force disabled and unsupported.")
+
+	peer1.V6Setting = nbpeer.V6Enabled
+	peer2.V6Setting = nbpeer.V6Enabled
+	_, err = manager.DeterminePeerV6(account, peer1)
+	require.NoError(t, err, "unable to determine effective peer IPv6 status")
+	_, err = manager.DeterminePeerV6(account, peer2)
+	require.Error(t, err, "determining peer2 IPv6 address should fail as it is force enabled, but unsupported.")
+	require.NotNil(t, peer1.IP6, "peer1 IPv6 address is nil even though it is force enabled.")
+	require.Nil(t, peer2.IP6, "peer2 IPv6 address is not nil even though it is unsupported.")
+
+	// Test whether disabling IPv6 will disable IPv6 routes.
+	allGroup, err := account.GetGroupAll()
+	require.NoError(t, err, "unable to retrieve all group")
+	route, err := manager.CreateRoute(account.Id, "2001:db8:2345:6789::/64", peer1.ID, make([]string, 0), "testroute", "testnet", false, 9999, []string{allGroup.ID}, true, userID)
+	require.NoError(t, err, "unable to create test IPv6 route")
+	require.True(t, route.Enabled, "created IPv6 test route should be enabled")
+
+	peer1.V6Setting = nbpeer.V6Disabled
+	_, err = manager.UpdatePeer(account.Id, userID, peer1)
+	require.NoError(t, err, "unable to update peer")
+
+	account, err = manager.Store.GetAccount(account.Id)
+	require.NoError(t, err, "unable to fetch updated account")
+
+	route = account.Routes[route.ID]
+	require.False(t, route.Enabled, "disabling IPv6 for a peer should disable all of its IPv6 routes.")
+}
+
 func TestAccountManager_GetNetworkMapWithPolicy(t *testing.T) {
 	// TODO: disable until we start use policy again
 	t.Skip()