WIP

cmd/vppn/main.go

@@ -45,7 +45,7 @@ func main() {
 	}
 
 	ifaceName := strings.TrimSuffix(state.LocalDomain, ".local")
-	app, err := peer.New(state, *hub, apiKey, ifaceName, state.LocalDomain)
+	app, err := peer.New(state, *hub, apiKey, ifaceName, state.LocalDomain, vppnPath(*name, "network.json"))
 	if err != nil {
 		log.Fatalf("start: %v", err)
 	}

peer/hub_poller.go

@@ -21,6 +21,7 @@ type HubPoller struct {
 	vpnNet    netip.Prefix
 	hubURL    string
 	apiKey    string
+	statePath string // where the network state cache is persisted
 	addCh     chan<- HubPeer
 	removeCh  chan<- wgtypes.Key
 	known     map[wgtypes.Key]int64 // pubKey → last seen version
@@ -30,6 +31,7 @@ func NewHubPoller(
 	selfVPNIP netip.Addr,
 	vpnNet netip.Prefix,
 	hubURL, apiKey string,
+	statePath string,
 	addCh chan<- HubPeer,
 	removeCh chan<- wgtypes.Key,
 ) (*HubPoller, error) {
@@ -44,6 +46,7 @@ func NewHubPoller(
 		vpnNet:    vpnNet,
 		hubURL:    u.String(),
 		apiKey:    apiKey,
+		statePath: statePath,
 		addCh:     addCh,
 		removeCh:  removeCh,
 		known:     make(map[wgtypes.Key]int64),
@@ -51,6 +54,14 @@ func NewHubPoller(
 }
 
 func (hp *HubPoller) Run() {
+	// Prime from the on-disk cache before reaching the hub, so the peer
+	// configures WireGuard from its last known state even if the hub is down.
+	// known starts empty, so this emits every cached peer as an add and seeds
+	// the version map; the first real poll then emits only deltas.
+	if state, err := loadNetworkState(hp.statePath); err == nil {
+		hp.apply(state)
+	}
+
 	hp.poll()
 	for range time.Tick(hubPollInterval) {
 		hp.poll()
@@ -90,10 +101,19 @@ func (hp *HubPoller) poll() {
 		return
 	}
 
-	hp.apply(state)
+	// Persist only when the state actually changed, to avoid needless writes
+	// on every poll.
+	if hp.apply(state) {
+		if err := saveNetworkState(hp.statePath, state); err != nil {
+			log.Printf("[HubPoller] save state: %v", err)
+		}
+	}
 }
 
-func (hp *HubPoller) apply(state m.NetworkState) {
+// apply diffs state against the known versions, emitting add events for new or
+// changed peers and remove events for peers that disappeared. It returns true
+// if anything changed.
+func (hp *HubPoller) apply(state m.NetworkState) (changed bool) {
 	seen := make(map[wgtypes.Key]struct{}, len(hp.known))
 
 	netAddr := hp.vpnNet.Addr().As4()
@@ -122,14 +142,18 @@ func (hp *HubPoller) apply(state m.NetworkState) {
 		}
 		hp.known[pubKey] = p.Version
 		hp.addCh <- hubPeerFrom(pubKey, vpnIP, p)
+		changed = true
 	}
 
 	for key := range hp.known {
 		if _, ok := seen[key]; !ok {
 			delete(hp.known, key)
 			hp.removeCh <- key
+			changed = true
 		}
 	}
+
+	return changed
 }
 
 func hubPeerFrom(pubKey wgtypes.Key, vpnIP netip.Addr, p *m.Peer) HubPeer {

peer/hub_poller_test.go

@@ -0,0 +1,99 @@
+package peer
+
+import (
+	"net/netip"
+	"testing"
+
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+
+	"vppn/m"
+)
+
+func testPoller(t *testing.T) (*HubPoller, chan HubPeer, chan wgtypes.Key) {
+	t.Helper()
+	addCh := make(chan HubPeer, 8)
+	removeCh := make(chan wgtypes.Key, 8)
+	hp := &HubPoller{
+		selfVPNIP: netip.MustParseAddr("10.0.0.1"),
+		vpnNet:    netip.MustParsePrefix("10.0.0.0/24"),
+		addCh:     addCh,
+		removeCh:  removeCh,
+		known:     make(map[wgtypes.Key]int64),
+	}
+	return hp, addCh, removeCh
+}
+
+func stateWith(key wgtypes.Key, peerIP byte, version int64) m.NetworkState {
+	var s m.NetworkState
+	s.Peers[peerIP] = &m.Peer{
+		PeerIP:     peerIP,
+		Version:    version,
+		WGPubKey:   key[:],
+		SignPubKey: make([]byte, 32),
+	}
+	return s
+}
+
+func TestApply_EmitsAddsAndReportsChange(t *testing.T) {
+	hp, addCh, _ := testPoller(t)
+	key := mustKey(t)
+
+	if changed := hp.apply(stateWith(key, 2, 1)); !changed {
+		t.Fatal("expected changed=true on first apply")
+	}
+	if len(addCh) != 1 {
+		t.Fatalf("expected 1 add, got %d", len(addCh))
+	}
+	if got := <-addCh; got.PubKey != key {
+		t.Errorf("add pubkey mismatch")
+	}
+}
+
+func TestApply_NoChangeWhenVersionSame(t *testing.T) {
+	hp, addCh, _ := testPoller(t)
+	key := mustKey(t)
+
+	hp.apply(stateWith(key, 2, 1))
+	<-addCh // drain initial add
+
+	if changed := hp.apply(stateWith(key, 2, 1)); changed {
+		t.Fatal("expected changed=false when version unchanged")
+	}
+	if len(addCh) != 0 {
+		t.Fatalf("expected no re-emit, got %d adds", len(addCh))
+	}
+}
+
+func TestApply_ReEmitsOnVersionBump(t *testing.T) {
+	hp, addCh, _ := testPoller(t)
+	key := mustKey(t)
+
+	hp.apply(stateWith(key, 2, 1))
+	<-addCh
+
+	if changed := hp.apply(stateWith(key, 2, 2)); !changed {
+		t.Fatal("expected changed=true on version bump")
+	}
+	if len(addCh) != 1 {
+		t.Fatalf("expected 1 re-emit, got %d", len(addCh))
+	}
+}
+
+func TestApply_RemovesVanishedPeer(t *testing.T) {
+	hp, addCh, removeCh := testPoller(t)
+	key := mustKey(t)
+
+	hp.apply(stateWith(key, 2, 1))
+	<-addCh
+
+	// Empty state: the peer is gone.
+	if changed := hp.apply(m.NetworkState{}); !changed {
+		t.Fatal("expected changed=true when peer vanishes")
+	}
+	if len(removeCh) != 1 {
+		t.Fatalf("expected 1 remove, got %d", len(removeCh))
+	}
+	if got := <-removeCh; got != key {
+		t.Errorf("remove key mismatch")
+	}
+}

peer/init.go

@@ -9,7 +9,6 @@ import (
 	"net/http"
 	"net/netip"
 	"os"
-	"path/filepath"
 
 	"golang.org/x/crypto/nacl/sign"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
@@ -32,21 +31,27 @@ type LocalState struct {
 
 // localStateJSON is the on-disk representation.
 type localStateJSON struct {
-	PrivKey     string       `json:"priv_key"`     // standard base64
-	SignKey     string       `json:"sign_key"`     // standard base64
-	VPNIP       netip.Addr   `json:"vpn_ip"`
-	VPNNet      netip.Prefix `json:"vpn_net"`
-	WGPort      uint16       `json:"wg_port"`
-	IsRelay     bool         `json:"is_relay"`
-	IsPublic    bool         `json:"is_public"`
-	LocalDomain string       `json:"local_domain"`
+	PrivKey     string
+	SignKey     string
+	VPNIP       netip.Addr
+	VPNNet      netip.Prefix
+	WGPort      uint16
+	IsRelay     bool
+	IsPublic    bool
+	LocalDomain string
 }
 
 // LoadOrInit loads LocalState from path, or registers with the hub and creates
 // the file if it doesn't exist.
 func LoadOrInit(statePath, hubURL, apiKey string) (LocalState, error) {
-	if data, err := os.ReadFile(statePath); err == nil {
-		return parseLocalState(data)
+	var state LocalState
+	switch err := loadJSON(statePath, &state); {
+	case err == nil:
+		return state, nil
+	case !os.IsNotExist(err):
+		// File exists but is unreadable/corrupt: surface it rather than
+		// silently regenerating a new identity and re-registering.
+		return LocalState{}, fmt.Errorf("load state: %w", err)
 	}
 
 	privKey, err := wgtypes.GeneratePrivateKey()
@@ -54,12 +59,12 @@ func LoadOrInit(statePath, hubURL, apiKey string) (LocalState, error) {
 		return LocalState{}, fmt.Errorf("generate key: %w", err)
 	}
 
-	state, err := initFromHub(hubURL, apiKey, privKey)
+	state, err = initFromHub(hubURL, apiKey, privKey)
 	if err != nil {
 		return LocalState{}, err
 	}
 
-	if err := saveLocalState(statePath, state); err != nil {
+	if err := storeJSON(statePath, state); err != nil {
 		return LocalState{}, fmt.Errorf("save state: %w", err)
 	}
 	return state, nil
@@ -130,42 +135,8 @@ func initFromHub(hubURL, apiKey string, privKey wgtypes.Key) (LocalState, error)
 	}, nil
 }
 
-func parseLocalState(data []byte) (LocalState, error) {
-	var j localStateJSON
-	if err := json.Unmarshal(data, &j); err != nil {
-		return LocalState{}, fmt.Errorf("parse state: %w", err)
-	}
-	keyBytes, err := base64.StdEncoding.DecodeString(j.PrivKey)
-	if err != nil {
-		return LocalState{}, fmt.Errorf("decode key: %w", err)
-	}
-	key, err := wgtypes.NewKey(keyBytes)
-	if err != nil {
-		return LocalState{}, fmt.Errorf("invalid key: %w", err)
-	}
-	signKeyBytes, err := base64.StdEncoding.DecodeString(j.SignKey)
-	if err != nil {
-		return LocalState{}, fmt.Errorf("decode sign key: %w", err)
-	}
-	if len(signKeyBytes) != 64 {
-		return LocalState{}, fmt.Errorf("invalid sign key length: %d", len(signKeyBytes))
-	}
-	var signKey [64]byte
-	copy(signKey[:], signKeyBytes)
-	return LocalState{
-		PrivKey:     key,
-		SignKey:     signKey,
-		VPNIP:       j.VPNIP,
-		VPNNet:      j.VPNNet,
-		WGPort:      j.WGPort,
-		IsRelay:     j.IsRelay,
-		IsPublic:    j.IsPublic,
-		LocalDomain: j.LocalDomain,
-	}, nil
-}
-
-func saveLocalState(path string, s LocalState) error {
-	j := localStateJSON{
+func (s LocalState) MarshalJSON() ([]byte, error) {
+	return json.Marshal(localStateJSON{
 		PrivKey:     base64.StdEncoding.EncodeToString(s.PrivKey[:]),
 		SignKey:     base64.StdEncoding.EncodeToString(s.SignKey[:]),
 		VPNIP:       s.VPNIP,
@@ -174,13 +145,38 @@ func saveLocalState(path string, s LocalState) error {
 		IsRelay:     s.IsRelay,
 		IsPublic:    s.IsPublic,
 		LocalDomain: s.LocalDomain,
-	}
-	data, err := json.MarshalIndent(j, "", "  ")
-	if err != nil {
-		return err
-	}
-	if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
-		return err
-	}
-	return os.WriteFile(path, data, 0600)
+	})
+}
+
+func (s *LocalState) UnmarshalJSON(data []byte) error {
+	var j localStateJSON
+	if err := json.Unmarshal(data, &j); err != nil {
+		return err
+	}
+	keyBytes, err := base64.StdEncoding.DecodeString(j.PrivKey)
+	if err != nil {
+		return fmt.Errorf("decode key: %w", err)
+	}
+	key, err := wgtypes.NewKey(keyBytes)
+	if err != nil {
+		return fmt.Errorf("invalid key: %w", err)
+	}
+	signKeyBytes, err := base64.StdEncoding.DecodeString(j.SignKey)
+	if err != nil {
+		return fmt.Errorf("decode sign key: %w", err)
+	}
+	if len(signKeyBytes) != 64 {
+		return fmt.Errorf("invalid sign key length: %d", len(signKeyBytes))
+	}
+	*s = LocalState{
+		PrivKey:     key,
+		SignKey:     [64]byte(signKeyBytes),
+		VPNIP:       j.VPNIP,
+		VPNNet:      j.VPNNet,
+		WGPort:      j.WGPort,
+		IsRelay:     j.IsRelay,
+		IsPublic:    j.IsPublic,
+		LocalDomain: j.LocalDomain,
+	}
+	return nil
 }

peer/network_state.go

@@ -0,0 +1,18 @@
+package peer
+
+import "vppn/m"
+
+// loadNetworkState reads a cached network state from disk. Any error (most
+// commonly a missing file on first run) is returned to the caller, which
+// treats it as "no cache available".
+func loadNetworkState(path string) (m.NetworkState, error) {
+	var state m.NetworkState
+	err := loadJSON(path, &state)
+	return state, err
+}
+
+// saveNetworkState writes state to path atomically (see storeJSON), so a crash
+// mid-write cannot leave a corrupt cache.
+func saveNetworkState(path string, state m.NetworkState) error {
+	return storeJSON(path, state)
+}

peer/network_state_test.go

@@ -0,0 +1,54 @@
+package peer
+
+import (
+	"path/filepath"
+	"reflect"
+	"testing"
+
+	"vppn/m"
+)
+
+func TestNetworkState_RoundTrip(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "network.json")
+
+	var state m.NetworkState
+	state.Peers[1] = &m.Peer{
+		PeerIP:     1,
+		Version:    7,
+		Name:       "hub",
+		Addr4:      []byte{10, 11, 12, 1},
+		Port:       51820,
+		Relay:      true,
+		WGPubKey:   make([]byte, 32),
+		SignPubKey: make([]byte, 32),
+	}
+	state.Peers[10] = &m.Peer{
+		PeerIP:     10,
+		Version:    3,
+		Name:       "laptop",
+		Addr4:      []byte{10, 11, 12, 10},
+		Port:       51820,
+		WGPubKey:   []byte("0123456789abcdef0123456789abcdef"),
+		SignPubKey: []byte("fedcba9876543210fedcba9876543210"),
+	}
+
+	if err := saveNetworkState(path, state); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := loadNetworkState(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(got, state) {
+		t.Errorf("round-trip mismatch:\n got: %+v\nwant: %+v", got.Peers[1], state.Peers[1])
+	}
+}
+
+func TestNetworkState_LoadMissing(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "does-not-exist.json")
+	if _, err := loadNetworkState(path); err == nil {
+		t.Fatal("expected error loading missing cache, got nil")
+	}
+}

peer/new.go

@@ -17,6 +17,7 @@ func New(
 	hubURL, apiKey string,
 	ifaceName string,
 	localDomain string,
+	networkStatePath string,
 ) (*App, error) {
 
 	a4 := state.VPNIP.As4()
@@ -50,10 +51,13 @@ func New(
 	multicastCh := make(chan MulticastEvent)
 
 	poller, err := NewHubPoller(
-		state.VPNIP, state.VPNNet,
-		hubURL, apiKey,
-		hubAddCh, hubRemoveCh,
-	)
+		state.VPNIP,
+		state.VPNNet,
+		hubURL,
+		apiKey,
+		networkStatePath,
+		hubAddCh,
+		hubRemoveCh)
 	if err != nil {
 		return nil, fmt.Errorf("hub poller: %w", err)
 	}