autopilotserver: add an autopilot server client

Add a client for the autopilot server along with a mock server that can
be used in tests.

Author: ellemouton

autopilotserver/client.go

@@ -0,0 +1,87 @@
+package autopilotserver
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/lightninglabs/lightning-terminal/autopilotserver/mock"
+	"github.com/lightningnetwork/lnd/lntest/wait"
+	"github.com/stretchr/testify/require"
+)
+
+// TestAutopilotClient tests that the Client correctly interacts with the
+// Autopilot server.
+func TestAutopilotClient(t *testing.T) {
+	ctx := context.Background()
+
+	// Spin up a new mock Autopilot server.
+	server := mock.NewServer()
+	require.NoError(t, server.Start())
+	t.Cleanup(server.Stop)
+
+	// Create a new client and connect it to the mock server. We set a very
+	// short ping cadence so that we can test that the client correctly
+	// ensures re-activation of a session.
+	addr := fmt.Sprintf("localhost:%d", server.GetPort())
+	client, err := NewClient(&Config{
+		Address:     addr,
+		Insecure:    true,
+		PingCadence: time.Second,
+	})
+	require.NoError(t, err)
+	require.NoError(t, client.Start())
+	t.Cleanup(client.Stop)
+
+	privKey, err := btcec.NewPrivateKey()
+	require.NoError(t, err)
+	pubKey := privKey.PubKey()
+
+	// Activating a session that the server does not yet know about should
+	// error.
+	_, err = client.ActivateSession(ctx, pubKey)
+	require.ErrorContains(t, err, "no such client")
+
+	// Register the client.
+	_, err = client.RegisterSession(ctx, pubKey, "", false, nil)
+	require.NoError(t, err)
+
+	// Assert that the server sees the new client and has it in the Active
+	// state.
+	state, err := server.GetClientState(pubKey)
+	require.NoError(t, err)
+	require.True(t, mock.ClientStateActive == state)
+
+	// Let the server move the client to an Inactive state.
+	err = server.SetClientState(pubKey, mock.ClientStateInactive)
+	require.NoError(t, err)
+	state, err = server.GetClientState(pubKey)
+	require.NoError(t, err)
+	require.True(t, mock.ClientStateInactive == state)
+
+	// Manually inform the server that the session is active.
+	_, err = client.ActivateSession(ctx, pubKey)
+	require.NoError(t, err)
+
+	// Assert that the server moved the client to the Active state.
+	state, err = server.GetClientState(pubKey)
+	require.NoError(t, err)
+	require.True(t, mock.ClientStateActive == state)
+
+	// Once again, let the server move the client to the inactive state.
+	err = server.SetClientState(pubKey, mock.ClientStateInactive)
+	require.NoError(t, err)
+	state, err = server.GetClientState(pubKey)
+	require.NoError(t, err)
+	require.True(t, mock.ClientStateInactive == state)
+
+	// Now wait for client to re-activate the session with the server
+	err = wait.Predicate(func() bool {
+		state, err = server.GetClientState(pubKey)
+		require.NoError(t, err)
+		return state == mock.ClientStateActive
+	}, time.Second*5)
+	require.NoError(t, err)
+}

autopilotserver/client_test.go

@@ -0,0 +1,80 @@
+package autopilotserver
+
+import (
+	"context"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"gopkg.in/macaroon-bakery.v2/bakery"
+)
+
+// Autopilot represents the functionality exposed by an autopilot server.
+type Autopilot interface {
+	// ListFeatures fetches the set of features offered by the autopilot
+	// server along with all the rules and permissions required for those
+	// features.
+	ListFeatures(ctx context.Context) (map[string]*Feature, error)
+
+	// ListFeaturePerms returns a map of feature names to a map of
+	// permissions required for each feature. This call uses an in-memory
+	// store that is updated periodically and so this should be used instead
+	// of the ListFeatures call if only the permissions are required to
+	// avoid doing multiple calls to the autopilot server. The ListFeatures
+	// call can however be used to force the update of the in-memory list.
+	ListFeaturePerms(ctx context.Context) (map[string]map[string]bool,
+		error)
+
+	// RegisterSession attempts to register a session with the autopilot
+	// server. If the registration is successful, then the Client will also
+	// track the session so that it can continuously ensure that the session
+	// remains active.
+	RegisterSession(ctx context.Context, pubKey *btcec.PublicKey,
+		mailboxAddr string, devServer bool,
+		featureConf map[string][]byte) (*btcec.PublicKey, error)
+
+	// ActivateSession attempts to inform the autopilot server that the
+	// given session is still active. After this is called, the autopilot
+	// client will periodically ensure that the session remains active.
+	// The boolean returned is true if the error received was permanent
+	// meaning that the session should be revoked and recreated.
+	ActivateSession(ctx context.Context, pubKey *btcec.PublicKey) (bool,
+		error)
+
+	// SessionRevoked should be called when a session is no longer active
+	// so that the client can forget the session.
+	SessionRevoked(ctx context.Context, key *btcec.PublicKey)
+
+	// Start kicks off the goroutines of the client.
+	Start(opts ...func(cfg *Config)) error
+
+	// Stop cleans up any resources held by the client.
+	Stop()
+}
+
+// Feature holds all the info necessary to subscribe to a feature offered by
+// the autopilot server.
+type Feature struct {
+	// Name is the name of the feature.
+	Name string
+
+	// Description is a human-readable description of what the feature
+	// offers
+	Description string
+
+	// Permissions is a list of RPC methods and access writes a feature
+	// will need.
+	Permissions map[string][]bakery.Op
+
+	// Rules is a list of all the firewall that must be specified for this
+	// feature.
+	Rules map[string]*RuleValues
+}
+
+// RuleValues holds the default value along with the sane max and min values
+// that the autopilot server indicates makes sense for feature that the rule is
+// being applied to. The values can be unmarshalled in a higher layer if the
+// name of the rule is known to LiT.
+type RuleValues struct {
+	Default []byte
+	MinVal  []byte
+	MaxVal  []byte
+}

autopilotserver/interface.go

@@ -0,0 +1,25 @@
+package autopilotserver
+
+import (
+	"github.com/btcsuite/btclog"
+	"github.com/lightningnetwork/lnd/build"
+)
+
+const Subsystem = "AUTO"
+
+// log is a logger that is initialized with no output filters.  This
+// means the package will not perform any logging by default until the caller
+// requests it.
+var log btclog.Logger
+
+// The default amount of logging is none.
+func init() {
+	UseLogger(build.NewSubLogger(Subsystem, nil))
+}
+
+// UseLogger uses a specified Logger to output package logging info.
+// This should be used in preference to SetLogWriter if the caller is also
+// using btclog.
+func UseLogger(logger btclog.Logger) {
+	log = logger
+}

autopilotserver/log.go

@@ -0,0 +1,25 @@
+package mock
+
+import (
+	"github.com/btcsuite/btclog"
+	"github.com/lightningnetwork/lnd/build"
+)
+
+const Subsystem = "AUTO"
+
+// log is a logger that is initialized with no output filters.  This
+// means the package will not perform any logging by default until the caller
+// requests it.
+var log btclog.Logger
+
+// The default amount of logging is none.
+func init() {
+	UseLogger(build.NewSubLogger(Subsystem, nil))
+}
+
+// UseLogger uses a specified Logger to output package logging info.
+// This should be used in preference to SetLogWriter if the caller is also
+// using btclog.
+func UseLogger(logger btclog.Logger) {
+	log = logger
+}