13974489001

Committed 20 Mar 2025 04:32PM UTC coverage: 56.292% (-2.9%) from 59.168%

Build # 13974489001

Build Type

Pull #8754

github

Committed by

web-flow

Commit Message

Merge aed149e6b into ea050d06f

Pull Request Pull Request #8754: Add `Outbound` Remote Signer implementation

Run Details

594 of 1713 new or added lines in 26 files covered. (34.68%)

23052 existing lines in 272 files now uncovered.

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0.0

/rpcperms/interceptor.go

package rpcperms

import (
        "context"
        "errors"
        "fmt"
        "sync"
        "sync/atomic"

        "github.com/btcsuite/btclog/v2"
        grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
        "github.com/lightningnetwork/lnd/lnrpc"
        "github.com/lightningnetwork/lnd/macaroons"
        "github.com/lightningnetwork/lnd/monitoring"
        "github.com/lightningnetwork/lnd/subscribe"
        "google.golang.org/grpc"
        "gopkg.in/macaroon-bakery.v2/bakery"
)

// rpcState is an enum that we use to keep track of the current RPC service
// state. This will transition as we go from startup to unlocking the wallet,
// and finally fully active.
type rpcState uint8

const (
        // waitingToStart indicates that we're at the beginning of the startup
        // process. In a cluster environment this may mean that we're waiting to
        // become the leader in which case RPC calls will be disabled until
        // this instance has been elected as leader.
        waitingToStart rpcState = iota

        // walletNotCreated is the starting state if the RPC server is active,
        // but the wallet is not yet created. In this state we'll only allow
        // calls to the WalletUnlockerService.
        walletNotCreated

        // walletLocked indicates the RPC server is active, but the wallet is
        // locked. In this state we'll only allow calls to the
        // WalletUnlockerService.
        walletLocked

        // walletUnlocked means that the wallet has been unlocked, but the full
        // RPC server is not yet ready.
        walletUnlocked

        // allowRemoteSigner means that the wallet is unlocked, and that we're
        // waiting for the remote signer to connect before proceeding. Only
        // rpc calls to connect the remote signer are allowed during this state.
        allowRemoteSigner

        // rpcActive means that the RPC server is ready to accept calls.
        rpcActive

        // serverActive means that the lnd server is ready to accept calls.
        serverActive
)

var (
        // ErrWaitingToStart is returned if LND is still waiting to start,
        // possibly blocked until elected as the leader.
        ErrWaitingToStart = fmt.Errorf("waiting to start, RPC services not " +
                "available")

        // ErrNoWallet is returned if the wallet does not exist.
        ErrNoWallet = fmt.Errorf("wallet not created, create one to enable " +
                "full RPC access")

        // ErrWalletLocked is returned if the wallet is locked and any service
        // other than the WalletUnlocker is called.
        ErrWalletLocked = fmt.Errorf("wallet locked, unlock it to enable " +
                "full RPC access")

        // ErrWalletUnlocked is returned if the WalletUnlocker service is
        // called when the wallet already has been unlocked.
        ErrWalletUnlocked = fmt.Errorf("wallet already unlocked, " +
                "WalletUnlocker service is no longer available")

        // ErrAwaitingRemoteSigner is returned if an RPC call is made, other
        // than an RPC call to connect a remote signer, while LND is waiting for
        // a remote signer to connect.
        ErrAwaitingRemoteSigner = fmt.Errorf("waiting for remote signer to " +
                "connect before other RPC calls can be accepted")

        // ErrRPCStarting is returned if the wallet has been unlocked but the
        // RPC server is not yet ready to accept calls.
        ErrRPCStarting = fmt.Errorf("the RPC server is in the process of " +
                "starting up, but not yet ready to accept calls")

        // macaroonWhitelist defines methods that we don't require macaroons to
        // access. We also allow these methods to be called even if not all
        // mandatory middlewares are registered yet. If the wallet is locked
        // then a middleware cannot register itself, creating an impossible
        // situation. Also, a middleware might want to check the state of lnd
        // by calling the State service before it registers itself. So we also
        // need to exclude those calls from the mandatory middleware check.
        macaroonWhitelist = map[string]struct{}{
                // We allow all calls to the WalletUnlocker without macaroons.
                "/lnrpc.WalletUnlocker/GenSeed":        {},
                "/lnrpc.WalletUnlocker/InitWallet":     {},
                "/lnrpc.WalletUnlocker/UnlockWallet":   {},
                "/lnrpc.WalletUnlocker/ChangePassword": {},

                // The State service must be available at all times, even
                // before we can check macaroons, so we whitelist it.
                "/lnrpc.State/SubscribeState": {},
                "/lnrpc.State/GetState":       {},
        }

        // allowRemoteSignerWhitelist defines methods that we allow to be called
        // when we are waiting for the remote signer to connect, i.e. in the
        // allowRemoteSigner state.
        allowRemoteSignerWhitelist = map[string]struct{}{
                "/walletrpc.WalletKit/SignCoordinatorStreams": {},
        }
)

// InterceptorChain is a struct that can be added to the running GRPC server,
// intercepting API calls. This is useful for logging, enforcing permissions,
// supporting middleware etc. The following diagram shows the order of each
// interceptor in the chain and when exactly requests/responses are intercepted
// and forwarded to external middleware for approval/modification. Middleware in
// general can only intercept gRPC requests/responses that are sent by the
// client with a macaroon that contains a custom caveat that is supported by one
// of the registered middlewares.
//
//            |
//            | gRPC request from client
//            |
//        +---v--------------------------------+
//        |   InterceptorChain                 |
//        +-+----------------------------------+
//          | Log Interceptor                  |
//          +----------------------------------+
//          | RPC State Interceptor            |
//          +----------------------------------+
//          | Macaroon Interceptor             |
//          +----------------------------------+--------> +---------------------+
//          | RPC Macaroon Middleware Handler  |<-------- | External Middleware |
//          +----------------------------------+          |   - modify request |
//          | Prometheus Interceptor           |          +---------------------+
//          +-+--------------------------------+
//            | validated gRPC request from client
//        +---v--------------------------------+
//        |   main gRPC server                 |
//        +---+--------------------------------+
//            |
//            | original gRPC request to client
//            |
//        +---v--------------------------------+--------> +---------------------+
//        |   RPC Macaroon Middleware Handler  |<-------- | External Middleware |
//        +---+--------------------------------+          |   - modify response |
//            |                                           +---------------------+
//            | edited gRPC request to client
//            v
type InterceptorChain struct {
        // lastRequestID is the ID of the last gRPC request or stream that was
        // intercepted by the middleware interceptor.
        //
        // NOTE: Must be used atomically!
        lastRequestID uint64

        // Required by the grpc-gateway/v2 library for forward compatibility.
        lnrpc.UnimplementedStateServer

        started sync.Once
        stopped sync.Once

        // state is the current RPC state of our RPC server.
        state rpcState

        // ntfnServer is a subscription server we use to notify clients of the
        // State service when the state changes.
        ntfnServer *subscribe.Server

        // noMacaroons should be set true if we don't want to check macaroons.
        noMacaroons bool

        // svc is the macaroon service used to enforce permissions in case
        // macaroons are used.
        svc *macaroons.Service

        // permissionMap is the permissions to enforce if macaroons are used.
        permissionMap map[string][]bakery.Op

        // rpcsLog is the logger used to log calls to the RPCs intercepted.
        rpcsLog btclog.Logger

        // registeredMiddleware is a slice of all macaroon permission based RPC
        // middleware clients that are currently registered. The
        // registeredMiddlewareNames can be used to find the index of a specific
        // interceptor within the registeredMiddleware slide using the name of
        // the interceptor as the key. The reason for using these two separate
        // structures is so that the order in which interceptors are run is
        // the same as the order in which they were registered.
        registeredMiddleware []*MiddlewareHandler

        // registeredMiddlewareNames is a map of registered middleware names
        // to the index at which they are stored in the registeredMiddleware
        // map.
        registeredMiddlewareNames map[string]int

        // mandatoryMiddleware is a list of all middleware that is considered to
        // be mandatory. If any of them is not registered then all RPC requests
        // (except for the macaroon white listed methods and the middleware
        // registration itself) are blocked. This is a security feature to make
        // sure that requests can't just go through unobserved/unaudited if a
        // middleware crashes.
        mandatoryMiddleware []string

        quit chan struct{}
        sync.RWMutex
}

// A compile time check to ensure that InterceptorChain fully implements the
// StateServer gRPC service.
var _ lnrpc.StateServer = (*InterceptorChain)(nil)

// NewInterceptorChain creates a new InterceptorChain.
func NewInterceptorChain(log btclog.Logger, noMacaroons bool,
        mandatoryMiddleware []string) *InterceptorChain {

        return &InterceptorChain{
                state:                     waitingToStart,
                ntfnServer:                subscribe.NewServer(),
                noMacaroons:               noMacaroons,
                permissionMap:             make(map[string][]bakery.Op),
                rpcsLog:                   log,
                registeredMiddlewareNames: make(map[string]int),
                mandatoryMiddleware:       mandatoryMiddleware,
                quit:                      make(chan struct{}),
        }
}

// Start starts the InterceptorChain, which is needed to start the state
// subscription server it powers.
func (r *InterceptorChain) Start() error {
        var err error
        r.started.Do(func() {
                err = r.ntfnServer.Start()
        })

        return err
}

// Stop stops the InterceptorChain and its internal state subscription server.
func (r *InterceptorChain) Stop() error {
        var err error
        r.stopped.Do(func() {
                close(r.quit)
                err = r.ntfnServer.Stop()
        })

        return err
}

// SetWalletNotCreated moves the RPC state from either waitingToStart to
// walletNotCreated.
func (r *InterceptorChain) SetWalletNotCreated() {
        r.Lock()
        defer r.Unlock()

        r.state = walletNotCreated
        _ = r.ntfnServer.SendUpdate(r.state)
}

// SetWalletLocked moves the RPC state from either walletNotCreated to
// walletLocked.
func (r *InterceptorChain) SetWalletLocked() {
        r.Lock()
        defer r.Unlock()

        r.state = walletLocked
        _ = r.ntfnServer.SendUpdate(r.state)
}

// SetWalletUnlocked moves the RPC state from either walletNotCreated or
// walletLocked to walletUnlocked.
func (r *InterceptorChain) SetWalletUnlocked() {
        r.Lock()
        defer r.Unlock()

        r.state = walletUnlocked
        _ = r.ntfnServer.SendUpdate(r.state)
}

// SetAllowRemoteSigner moves the RPC state from walletUnlocked to
// waitRemoteSigner.
func (r *InterceptorChain) SetAllowRemoteSigner() {
        r.Lock()
        defer r.Unlock()

        r.state = allowRemoteSigner
        _ = r.ntfnServer.SendUpdate(r.state)
}

// SetRPCActive moves the RPC state from either walletUnlocked or
// waitRemoteSigner to rpcActive.
func (r *InterceptorChain) SetRPCActive() {
        r.Lock()
        defer r.Unlock()

        r.state = rpcActive
        _ = r.ntfnServer.SendUpdate(r.state)
}

// SetServerActive moves the RPC state from rpcActive to serverActive.
func (r *InterceptorChain) SetServerActive() {
        r.Lock()
        defer r.Unlock()

        r.state = serverActive
        _ = r.ntfnServer.SendUpdate(r.state)
}

// rpcStateToWalletState converts rpcState to lnrpc.WalletState. Returns
// WAITING_TO_START and an error on conversion error.
func rpcStateToWalletState(state rpcState) (lnrpc.WalletState, error) {
        const defaultState = lnrpc.WalletState_WAITING_TO_START
        var walletState lnrpc.WalletState

        switch state {
        case waitingToStart:
                walletState = lnrpc.WalletState_WAITING_TO_START
        case walletNotCreated:
                walletState = lnrpc.WalletState_NON_EXISTING
        case walletLocked:
                walletState = lnrpc.WalletState_LOCKED
        case walletUnlocked:
                walletState = lnrpc.WalletState_UNLOCKED
        case allowRemoteSigner:
                walletState = lnrpc.WalletState_ALLOW_REMOTE_SIGNER
        case rpcActive:
                walletState = lnrpc.WalletState_RPC_ACTIVE
        case serverActive:
                walletState = lnrpc.WalletState_SERVER_ACTIVE

        default:
                return defaultState, fmt.Errorf("unknown wallet state %v", state)
        }

        return walletState, nil
}

// SubscribeState subscribes to the state of the wallet. The current wallet
// state will always be delivered immediately.
//
// NOTE: Part of the StateService interface.
func (r *InterceptorChain) SubscribeState(_ *lnrpc.SubscribeStateRequest,
        stream lnrpc.State_SubscribeStateServer) error {

        sendStateUpdate := func(state rpcState) error {
                walletState, err := rpcStateToWalletState(state)
                if err != nil {
                        return err
                }

                return stream.Send(&lnrpc.SubscribeStateResponse{
                        State: walletState,
                })
        }

        // Subscribe to state updates.
        client, err := r.ntfnServer.Subscribe()
        if err != nil {
                return err
        }
        defer client.Cancel()

        // Always start by sending the current state.
        r.RLock()
        state := r.state
        r.RUnlock()

        if err := sendStateUpdate(state); err != nil {
                return err
        }

        for {
                select {
                case e := <-client.Updates():
                        newState := e.(rpcState)

                        // Ignore already sent state.
                        if newState == state {
                                continue
                        }

                        state = newState
                        err := sendStateUpdate(state)
                        if err != nil {
                                return err
                        }

                // The response stream's context for whatever reason has been
                // closed. If context is closed by an exceeded deadline we will
                // return an error.
                case <-stream.Context().Done():
                        if errors.Is(stream.Context().Err(), context.Canceled) {
                                return nil
                        }
                        return stream.Context().Err()

                case <-r.quit:
                        return fmt.Errorf("server exiting")
                }
        }
}

// GetState returns the current wallet state.
func (r *InterceptorChain) GetState(_ context.Context,
        _ *lnrpc.GetStateRequest) (*lnrpc.GetStateResponse, error) {

        r.RLock()
        state := r.state
        r.RUnlock()

        walletState, err := rpcStateToWalletState(state)
        if err != nil {
                return nil, err
        }

        return &lnrpc.GetStateResponse{
                State: walletState,
        }, nil
}

// AddMacaroonService adds a macaroon service to the interceptor. After this is
// done every RPC call made will have to pass a valid macaroon to be accepted.
func (r *InterceptorChain) AddMacaroonService(svc *macaroons.Service) {
        r.Lock()
        defer r.Unlock()

        r.svc = svc
}

// MacaroonService returns the currently registered macaroon service. This might
// be nil if none was registered (yet).
func (r *InterceptorChain) MacaroonService() *macaroons.Service {
        r.RLock()
        defer r.RUnlock()

        return r.svc
}

// AddPermission adds a new macaroon rule for the given method.
func (r *InterceptorChain) AddPermission(method string, ops []bakery.Op) error {
        r.Lock()
        defer r.Unlock()

        if _, ok := r.permissionMap[method]; ok {
                return fmt.Errorf("detected duplicate macaroon constraints "+
                        "for path: %v", method)
        }

        r.permissionMap[method] = ops
        return nil
}

// Permissions returns the current set of macaroon permissions.
func (r *InterceptorChain) Permissions() map[string][]bakery.Op {
        r.RLock()
        defer r.RUnlock()

        // Make a copy under the read lock to avoid races.
        c := make(map[string][]bakery.Op)
        for k, v := range r.permissionMap {
                s := make([]bakery.Op, len(v))
                copy(s, v)
                c[k] = s
        }

        return c
}

// RegisterMiddleware registers a new middleware that will handle request/
// response interception for all RPC messages that are initiated with a custom
// macaroon caveat. The name of the custom caveat a middleware is handling is
// also its unique identifier. Only one middleware can be registered for each
// custom caveat.
func (r *InterceptorChain) RegisterMiddleware(mw *MiddlewareHandler) error {
        r.Lock()
        defer r.Unlock()

        // The name of the middleware is the unique identifier.
        _, ok := r.registeredMiddlewareNames[mw.middlewareName]
        if ok {
                return fmt.Errorf("a middleware with the name '%s' is already "+
                        "registered", mw.middlewareName)
        }

        // For now, we only want one middleware per custom caveat name. If we
        // allowed multiple middlewares handling the same caveat there would be
        // a need for extra call chaining logic, and they could overwrite each
        // other's responses.
        for _, middleware := range r.registeredMiddleware {
                if middleware.customCaveatName == mw.customCaveatName {
                        return fmt.Errorf("a middleware is already registered "+
                                "for the custom caveat name '%s': %v",
                                mw.customCaveatName, middleware.middlewareName)
                }
        }

        r.registeredMiddleware = append(r.registeredMiddleware, mw)
        index := len(r.registeredMiddleware) - 1
        r.registeredMiddlewareNames[mw.middlewareName] = index

        return nil
}

// RemoveMiddleware removes the middleware that handles the given custom caveat
// name.
func (r *InterceptorChain) RemoveMiddleware(middlewareName string) {
        r.Lock()
        defer r.Unlock()

        log.Debugf("Removing middleware %s", middlewareName)

        index, ok := r.registeredMiddlewareNames[middlewareName]
        if !ok {
                return
        }
        delete(r.registeredMiddlewareNames, middlewareName)

        r.registeredMiddleware = append(
                r.registeredMiddleware[:index],
                r.registeredMiddleware[index+1:]...,
        )

        // Re-initialise the middleware look-up map with the updated indexes.
        r.registeredMiddlewareNames = make(map[string]int)
        for i, mw := range r.registeredMiddleware {
                r.registeredMiddlewareNames[mw.middlewareName] = i
        }
}

// CustomCaveatSupported makes sure a middleware that handles the given custom
// caveat name is registered. If none is, an error is returned, signalling to
// the macaroon bakery and its validator to reject macaroons that have a custom
// caveat with that name.
//
// NOTE: This method is part of the macaroons.CustomCaveatAcceptor interface.
func (r *InterceptorChain) CustomCaveatSupported(customCaveatName string) error {
        r.RLock()
        defer r.RUnlock()

        // We only accept requests with a custom caveat if we also have a
        // middleware registered that handles that custom caveat. That is
        // crucial for security! Otherwise a request with an encumbered (=has
        // restricted permissions based upon the custom caveat condition)
        // macaroon would not be validated against the limitations that the
        // custom caveat implicate. Since the map is keyed by the _name_ of the
        // middleware, we need to loop through all of them to see if one has
        // the given custom macaroon caveat name.
        for _, middleware := range r.registeredMiddleware {
                if middleware.customCaveatName == customCaveatName {
                        return nil
                }
        }

        return fmt.Errorf("cannot accept macaroon with custom caveat '%s', "+
                "no middleware registered to handle it", customCaveatName)
}

// CreateServerOpts creates the GRPC server options that can be added to a GRPC
// server in order to add this InterceptorChain.
func (r *InterceptorChain) CreateServerOpts() []grpc.ServerOption {
        var unaryInterceptors []grpc.UnaryServerInterceptor
        var strmInterceptors []grpc.StreamServerInterceptor

        // The first interceptors we'll add to the chain is our logging
        // interceptors, so we can automatically log all errors that happen
        // during RPC calls.
        unaryInterceptors = append(
                unaryInterceptors, errorLogUnaryServerInterceptor(r.rpcsLog),
        )
        strmInterceptors = append(
                strmInterceptors, errorLogStreamServerInterceptor(r.rpcsLog),
        )

        // Next we'll add our RPC state check interceptors, that will check
        // whether the attempted call is allowed in the current state.
        unaryInterceptors = append(
                unaryInterceptors, r.rpcStateUnaryServerInterceptor(),
        )
        strmInterceptors = append(
                strmInterceptors, r.rpcStateStreamServerInterceptor(),
        )

        // We'll add the macaroon interceptors. If macaroons aren't disabled,
        // then these interceptors will enforce macaroon authentication.
        unaryInterceptors = append(
                unaryInterceptors, r.MacaroonUnaryServerInterceptor(),
        )
        strmInterceptors = append(
                strmInterceptors, r.MacaroonStreamServerInterceptor(),
        )

        // Next, we'll add the interceptors for our custom macaroon caveat based
        // middleware.
        unaryInterceptors = append(
                unaryInterceptors, r.middlewareUnaryServerInterceptor(),
        )
        strmInterceptors = append(
                strmInterceptors, r.middlewareStreamServerInterceptor(),
        )

        // Get interceptors for Prometheus to gather gRPC performance metrics.
        // If monitoring is disabled, GetPromInterceptors() will return empty
        // slices.
        promUnaryInterceptors, promStrmInterceptors :=
                monitoring.GetPromInterceptors()

        // Concatenate the slices of unary and stream interceptors respectively.
        unaryInterceptors = append(unaryInterceptors, promUnaryInterceptors...)
        strmInterceptors = append(strmInterceptors, promStrmInterceptors...)

        // Create server options from the interceptors we just set up.
        chainedUnary := grpc_middleware.WithUnaryServerChain(
                unaryInterceptors...,
        )
        chainedStream := grpc_middleware.WithStreamServerChain(
                strmInterceptors...,
        )
        serverOpts := []grpc.ServerOption{chainedUnary, chainedStream}

        return serverOpts
}

// errorLogUnaryServerInterceptor is a simple UnaryServerInterceptor that will
// automatically log any errors that occur when serving a client's unary
// request.
func errorLogUnaryServerInterceptor(logger btclog.Logger) grpc.UnaryServerInterceptor {
        return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo,
                handler grpc.UnaryHandler) (interface{}, error) {

                resp, err := handler(ctx, req)
                if err != nil {
                        // TODO(roasbeef): also log request details?
                        logger.Errorf("[%v]: %v", info.FullMethod, err)
                }

                return resp, err
        }
}

// errorLogStreamServerInterceptor is a simple StreamServerInterceptor that
// will log any errors that occur while processing a client or server streaming
// RPC.
func errorLogStreamServerInterceptor(logger btclog.Logger) grpc.StreamServerInterceptor {
        return func(srv interface{}, ss grpc.ServerStream,
                info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {

                err := handler(srv, ss)
                if err != nil {
                        logger.Errorf("[%v]: %v", info.FullMethod, err)
                }

                return err
        }
}

// checkMacaroon validates that the context contains the macaroon needed to
// invoke the given RPC method.
func (r *InterceptorChain) checkMacaroon(ctx context.Context,
        fullMethod string) error {

        // If noMacaroons is set, we'll always allow the call.
        if r.noMacaroons {
                return nil
        }

        // Check whether the method is whitelisted, if so we'll allow it
        // regardless of macaroons.
        _, ok := macaroonWhitelist[fullMethod]
        if ok {
                return nil
        }

        r.RLock()
        svc := r.svc
        r.RUnlock()

        // If the macaroon service is not yet active, we cannot allow
        // the call.
        if svc == nil {
                return fmt.Errorf("unable to determine macaroon permissions")
        }

        r.RLock()
        uriPermissions, ok := r.permissionMap[fullMethod]
        r.RUnlock()
        if !ok {
                return fmt.Errorf("%s: unknown permissions required for method",
                        fullMethod)
        }

        // Find out if there is an external validator registered for
        // this method. Fall back to the internal one if there isn't.
        validator, ok := svc.ExternalValidators[fullMethod]
        if !ok {
                validator = svc
        }

        // Now that we know what validator to use, let it do its work.
        return validator.ValidateMacaroon(ctx, uriPermissions, fullMethod)
}

// MacaroonUnaryServerInterceptor is a GRPC interceptor that checks whether the
// request is authorized by the included macaroons.
func (r *InterceptorChain) MacaroonUnaryServerInterceptor() grpc.UnaryServerInterceptor {
        return func(ctx context.Context, req interface{},
                info *grpc.UnaryServerInfo,
                handler grpc.UnaryHandler) (interface{}, error) {

                // Check macaroons.
                if err := r.checkMacaroon(ctx, info.FullMethod); err != nil {
                        return nil, err
                }

                return handler(ctx, req)
        }
}

// MacaroonStreamServerInterceptor is a GRPC interceptor that checks whether
// the request is authorized by the included macaroons.
func (r *InterceptorChain) MacaroonStreamServerInterceptor() grpc.StreamServerInterceptor {
        return func(srv interface{}, ss grpc.ServerStream,
                info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {

                // Check macaroons.
                err := r.checkMacaroon(ss.Context(), info.FullMethod)
                if err != nil {
                        return err
                }

                return handler(srv, ss)
        }
}

// checkRPCState checks whether a call to the given server is allowed in the
// current RPC state.
func (r *InterceptorChain) checkRPCState(srv interface{},
        fullMethod string) error {

        // The StateService is being accessed, we allow the call regardless of
        // the current state.
        _, ok := srv.(lnrpc.StateServer)
        if ok {
                return nil
        }

        r.RLock()
        state := r.state
        r.RUnlock()

        switch state {
        // Do not accept any RPC calls (unless to the state service) until LND
        // has not started.
        case waitingToStart:
                return ErrWaitingToStart

        // If the wallet does not exists, only calls to the WalletUnlocker are
        // accepted.
        case walletNotCreated:
                _, ok := srv.(lnrpc.WalletUnlockerServer)
                if !ok {
                        return ErrNoWallet
                }

        // If the wallet is locked, only calls to the WalletUnlocker are
        // accepted.
        case walletLocked:
                _, ok := srv.(lnrpc.WalletUnlockerServer)
                if !ok {
                        return ErrWalletLocked
                }

        // If the wallet is unlocked, but the RPC not yet active, we reject.
        case walletUnlocked:
                _, ok := srv.(lnrpc.WalletUnlockerServer)
                if ok {
                        return ErrWalletUnlocked
                }

                return ErrRPCStarting

        // If lnd is waiting for the remote signer to connect, we only allow
        // calls to the remote signer.
        case allowRemoteSigner:
                _, ok := srv.(lnrpc.WalletUnlockerServer)
                if ok {
                        return ErrWalletUnlocked
                }

                // As we only allow calls to connect the remote signer until the
                // full rpc server is active, we check whether the method is
                // whitelisted or not.
                _, ok = allowRemoteSignerWhitelist[fullMethod]
                if !ok {
                        return ErrAwaitingRemoteSigner
                }

        // If the RPC server or lnd server is active, we allow calls to any
        // service except the WalletUnlocker.
        case rpcActive, serverActive:
                _, ok := srv.(lnrpc.WalletUnlockerServer)
                if ok {
                        return ErrWalletUnlocked
                }

        default:
                return fmt.Errorf("unknown RPC state: %v", state)
        }

        return nil
}

// rpcStateUnaryServerInterceptor is a GRPC interceptor that checks whether
// calls to the given gGRPC server is allowed in the current rpc state.
func (r *InterceptorChain) rpcStateUnaryServerInterceptor() grpc.UnaryServerInterceptor {
        return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo,
                handler grpc.UnaryHandler) (interface{}, error) {

                method := info.FullMethod
                r.rpcsLog.Debugf("[%v] requested", method)

                if err := r.checkRPCState(info.Server, method); err != nil {
                        return nil, err
                }

                return handler(ctx, req)
        }
}

// rpcStateStreamServerInterceptor is a GRPC interceptor that checks whether
// calls to the given gGRPC server is allowed in the current rpc state.
func (r *InterceptorChain) rpcStateStreamServerInterceptor() grpc.StreamServerInterceptor {
        return func(srv interface{}, ss grpc.ServerStream,
                info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {

                r.rpcsLog.Debugf("[%v] requested", info.FullMethod)

                if err := r.checkRPCState(srv, info.FullMethod); err != nil {
                        return err
                }

                return handler(srv, ss)
        }
}

// middlewareUnaryServerInterceptor is a unary gRPC interceptor that intercepts
// all requests and responses that are sent with a macaroon containing a custom
// caveat condition that is handled by registered middleware.
func (r *InterceptorChain) middlewareUnaryServerInterceptor() grpc.UnaryServerInterceptor {
        return func(ctx context.Context,
                req interface{}, info *grpc.UnaryServerInfo,
                handler grpc.UnaryHandler) (interface{}, error) {

                // Make sure we don't allow any requests through if one of the
                // mandatory middlewares is missing.
                fullMethod := info.FullMethod
                if err := r.checkMandatoryMiddleware(fullMethod); err != nil {
                        return nil, err
                }

                // If there is no middleware registered, we don't need to
                // intercept anything.
                if !r.middlewareRegistered() {
                        return handler(ctx, req)
                }

                requestID := atomic.AddUint64(&r.lastRequestID, 1)
                req, err := r.interceptMessage(
                        ctx, TypeRequest, requestID, false, info.FullMethod,
                        req,
                )
                if err != nil {
                        return nil, err
                }

                // Call the handler, which executes the request against lnd.
                lndResp, lndErr := handler(ctx, req)
                if lndErr != nil {
                        // The call to lnd ended in an error and not a normal
                        // proto message response. Send the error to the
                        // interceptor as well to inform about the abnormal
                        // termination of the stream and to give the option to
                        // replace the error message with a custom one.
                        replacedErr, err := r.interceptMessage(
                                ctx, TypeResponse, requestID, false,
                                info.FullMethod, lndErr,
                        )
                        if err != nil {
                                return nil, err
                        }
                        return lndResp, replacedErr.(error)
                }

                return r.interceptMessage(
                        ctx, TypeResponse, requestID, false, info.FullMethod,
                        lndResp,
                )
        }
}

// middlewareStreamServerInterceptor is a streaming gRPC interceptor that
// intercepts all requests and responses that are sent with a macaroon
// containing a custom caveat condition that is handled by registered
// middleware.
func (r *InterceptorChain) middlewareStreamServerInterceptor() grpc.StreamServerInterceptor {
        return func(srv interface{},
                ss grpc.ServerStream, info *grpc.StreamServerInfo,
                handler grpc.StreamHandler) error {

                // Don't intercept the interceptor itself which is a streaming
                // RPC too!
                fullMethod := info.FullMethod
                if fullMethod == lnrpc.RegisterRPCMiddlewareURI {
                        return handler(srv, ss)
                }

                // Make sure we don't allow any requests through if one of the
                // mandatory middlewares is missing. We add this check here to
                // make sure the middleware registration itself can still be
                // called.
                if err := r.checkMandatoryMiddleware(fullMethod); err != nil {
                        return err
                }

                // If there is no middleware registered, we don't need to
                // intercept anything.
                if !r.middlewareRegistered() {
                        return handler(srv, ss)
                }

                // To give the middleware a chance to accept or reject the
                // establishment of the stream itself (and not only when the
                // first message is sent on the stream), we send an intercept
                // request for the stream auth now:
                msg, err := NewStreamAuthInterceptionRequest(
                        ss.Context(), info.FullMethod,
                )
                if err != nil {
                        return err
                }

                requestID := atomic.AddUint64(&r.lastRequestID, 1)
                err = r.acceptStream(requestID, msg)
                if err != nil {
                        return err
                }

                wrappedSS := &serverStreamWrapper{
                        ServerStream: ss,
                        requestID:    requestID,
                        fullMethod:   info.FullMethod,
                        interceptor:  r,
                }

                // Call the stream handler, which will block as long as the
                // stream is alive.
                lndErr := handler(srv, wrappedSS)
                if lndErr != nil {
                        // This is an error being returned from lnd. Send it to
                        // the interceptor as well to inform about the abnormal
                        // termination of the stream and to give the option to
                        // replace the error message with a custom one.
                        replacedErr, err := r.interceptMessage(
                                ss.Context(), TypeResponse, requestID,
                                true, info.FullMethod, lndErr,
                        )
                        if err != nil {
                                return err
                        }

                        return replacedErr.(error)
                }

                // Normal/successful termination of the stream.
                return nil
        }
}

// checkMandatoryMiddleware makes sure that each of the middlewares declared as
// mandatory is currently registered.
func (r *InterceptorChain) checkMandatoryMiddleware(fullMethod string) error {
        r.RLock()
        defer r.RUnlock()

        // Allow calls that are whitelisted for macaroons as well, otherwise we
        // get into impossible situations where the wallet is locked but the
        // unlock call is denied because the middleware isn't registered. But
        // the middleware cannot register itself because the wallet is locked.
        if _, ok := macaroonWhitelist[fullMethod]; ok {
                return nil
        }

        // Not a white listed call so make sure every mandatory middleware is
        // currently connected to lnd.
        for _, name := range r.mandatoryMiddleware {
                if _, ok := r.registeredMiddlewareNames[name]; !ok {
                        return fmt.Errorf("mandatory middleware '%s' is "+
                                "currently not registered, not allowing any "+
                                "RPC calls", name)
                }
        }

        return nil
}

// middlewareRegistered returns true if there is at least one middleware
// currently registered.
func (r *InterceptorChain) middlewareRegistered() bool {
        r.RLock()
        defer r.RUnlock()

        return len(r.registeredMiddleware) > 0
}

// acceptStream sends an intercept request to all middlewares that have
// registered for it. This means either a middleware has requested read-only
// access or the request actually has a macaroon with a caveat the middleware
// registered for.
func (r *InterceptorChain) acceptStream(requestID uint64,
        msg *InterceptionRequest) error {

        r.RLock()
        defer r.RUnlock()

        for _, middleware := range r.registeredMiddleware {
                // If there is a custom caveat in the macaroon, make sure the
                // middleware registered for it. Or if a middleware registered
                // for read-only mode, it also gets the request.
                hasCustomCaveat := macaroons.HasCustomCaveat(
                        msg.Macaroon, middleware.customCaveatName,
                )
                if !hasCustomCaveat && !middleware.readOnly {
                        continue
                }

                msg.CustomCaveatCondition = macaroons.GetCustomCaveatCondition(
                        msg.Macaroon, middleware.customCaveatName,
                )

                resp, err := middleware.intercept(requestID, msg)

                // Error during interception itself.
                if err != nil {
                        return err
                }

                // Error returned from middleware client.
                if resp.err != nil {
                        return resp.err
                }
        }

        return nil
}

// interceptMessage sends out an intercept request for an RPC response. Since
// middleware that hasn't registered for the read-only mode has the option to
// overwrite/replace the message, this needs to be handled differently than the
// auth path above.
func (r *InterceptorChain) interceptMessage(ctx context.Context,
        interceptType InterceptType, requestID uint64, isStream bool,
        fullMethod string, m interface{}) (interface{}, error) {

        r.RLock()
        defer r.RUnlock()

        currentMessage := m
        for _, middleware := range r.registeredMiddleware {
                msg, err := NewMessageInterceptionRequest(
                        ctx, interceptType, isStream, fullMethod,
                        currentMessage,
                )
                if err != nil {
                        return nil, err
                }

                // If there is a custom caveat in the macaroon, make sure the
                // middleware registered for it. Or if a middleware registered
                // for read-only mode, it also gets the request.
                hasCustomCaveat := macaroons.HasCustomCaveat(
                        msg.Macaroon, middleware.customCaveatName,
                )
                if !hasCustomCaveat && !middleware.readOnly {
                        continue
                }

                msg.CustomCaveatCondition = macaroons.GetCustomCaveatCondition(
                        msg.Macaroon, middleware.customCaveatName,
                )

                resp, err := middleware.intercept(requestID, msg)

                // Error during interception itself.
                if err != nil {
                        return nil, err
                }

                // Error returned from middleware client.
                if resp.err != nil {
                        return nil, resp.err
                }

                // The message was replaced, make sure the next middleware in
                // line receives the updated message.
                if !middleware.readOnly && resp.replace {
                        currentMessage = resp.replacement
                }
        }

        return currentMessage, nil
}

// serverStreamWrapper is a struct that wraps a server stream in a way that all
// requests and responses can be intercepted individually.
type serverStreamWrapper struct {
        // ServerStream is the stream that's being wrapped.
        grpc.ServerStream

        requestID uint64

        fullMethod string

        interceptor *InterceptorChain
}

// SendMsg is called when lnd sends a message to the client. This is wrapped to
// intercept streaming RPC responses.
func (w *serverStreamWrapper) SendMsg(m interface{}) error {
        newMsg, err := w.interceptor.interceptMessage(
                w.ServerStream.Context(), TypeResponse, w.requestID, true,
                w.fullMethod, m,
        )
        if err != nil {
                return err
        }

        return w.ServerStream.SendMsg(newMsg)
}

// RecvMsg is called when lnd wants to receive a message from the client. This
// is wrapped to intercept streaming RPC requests.
func (w *serverStreamWrapper) RecvMsg(m interface{}) error {
        err := w.ServerStream.RecvMsg(m)
        if err != nil {
                return err
        }

        req, err := w.interceptor.interceptMessage(
                w.ServerStream.Context(), TypeRequest, w.requestID, true,
                w.fullMethod, m,
        )
        if err != nil {
                return err
        }

        return replaceProtoMsg(m, req)
}

lightningnetwork / lnd / 13974489001

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