13440912774

Committed 20 Feb 2025 05:14PM UTC coverage: 57.697% (-1.1%) from 58.802%

Build # 13440912774

Build Type

Pull #9535

github

Committed by

guggero

Commit Message

GitHub: remove duplicate caching

Turns out that actions/setup-go starting with @v4 also adds caching.
With that, our cache size on disk has almost doubled, leading to the
GitHub runner running out of space in certain situation.
We fix that by disabling the automated caching since we already have our
own, custom-tailored version.

Pull Request Pull Request #9535: GitHub: remove duplicate caching

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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

        // 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")

        // 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":       {},
        }
)

// 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)
}

// SetRPCActive moves the RPC state from walletUnlocked 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 walletUnlocked to rpcActive.
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 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{}) 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 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) {

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

                if err := r.checkRPCState(info.Server); 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); 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 / 13440912774

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