feat(core): added support of the TLS certificates along with x-token authorisation token for the gRPC connection

nodebuilder/core/config.go

@@ -19,13 +19,19 @@ type Config struct {
 	IP       string
 	RPCPort  string
 	GRPCPort string
+	// TLSEnabled specifies whether the connection is secure or not.
+	// PLEASE NOTE: it should be set to true in order to handle XTokenPath.
+	TLSEnabled bool
+	// XTokenPath specifies the path to the directory with JSON file containing the X-Token for gRPC authentication.
+	// The JSON file should have a key-value pair where the key is "x-token" and the value is the authentication token.
+	// If left empty, the client will not include the X-Token in its requests.
+	XTokenPath string
 }
 
 // DefaultConfig returns default configuration for managing the
 // node's connection to a Celestia-Core endpoint.
 func DefaultConfig() Config {
 	return Config{
-		IP:       "",
 		RPCPort:  DefaultRPCPort,
 		GRPCPort: DefaultGRPCPort,
 	}

nodebuilder/core/flags.go

@@ -8,9 +8,11 @@ import (
 )
 
 var (
-	coreFlag     = "core.ip"
-	coreRPCFlag  = "core.rpc.port"
-	coreGRPCFlag = "core.grpc.port"
+	coreFlag           = "core.ip"
+	coreRPCFlag        = "core.rpc.port"
+	coreGRPCFlag       = "core.grpc.port"
+	coreTLS            = "core.tls"
+	coreXTokenPathFlag = "core.xtoken.path" //nolint:gosec
 )
 
 // Flags gives a set of hardcoded Core flags.
@@ -34,6 +36,19 @@ func Flags() *flag.FlagSet {
 		DefaultGRPCPort,
 		"Set a custom gRPC port for the core node connection. The --core.ip flag must also be provided.",
 	)
+	flags.Bool(
+		coreTLS,
+		false,
+		"Specifies whether TLS is enabled or not. Default: false",
+	)
+	flags.String(
+		coreXTokenPathFlag,
+		"",
+		"specifies the file path to the JSON file containing the X-Token for gRPC authentication. "+
+			"The JSON file should have a key-value pair where the key is 'x-token' and the value is the authentication token. "+
+			"NOTE: the path is parsed only if coreTLS enabled."+
+			"If left empty, the client will not include the X-Token in its requests.",
+	)
 	return flags
 }
 
@@ -60,6 +75,18 @@ func ParseFlags(
 		cfg.GRPCPort = grpc
 	}
 
+	enabled, err := cmd.Flags().GetBool(coreTLS)
+	if err != nil {
+		panic(err)
+	}
+
+	if enabled {
+		cfg.TLSEnabled = true
+		if cmd.Flag(coreXTokenPathFlag).Changed {
+			path := cmd.Flag(coreXTokenPathFlag).Value.String()
+			cfg.XTokenPath = path
+		}
+	}
 	cfg.IP = coreIP
 	return cfg.Validate()
 }

nodebuilder/core/tls.go

@@ -0,0 +1,58 @@
+package core
+
+import (
+	"crypto/tls"
+	"encoding/json"
+	"errors"
+	"os"
+	"path/filepath"
+
+	"github.com/celestiaorg/celestia-node/libs/utils"
+)
+
+const (
+	cert   = "cert.pem"
+	key    = "key.pem"
+	xtoken = "xtoken.json"
+)
+
+func EmptyTLSConfig() *tls.Config {
+	return &tls.Config{MinVersion: tls.VersionTLS12}
+}
+
+type AuthToken struct {
+	Token string `json:"x-token"`
+}
+
+// XToken retrieves the authentication token from a JSON file at the specified path.
+// It first constructs the full file path by joining the provided directory path with the token file name.
+// If the file does not exist, it returns an os.ErrNotExist error.
+// If the file exists, it reads the content and unmarshalls it.
+// If the field in the unmarshalled struct is empty, an error is returned indicating that the token is missing.
+// Parameters:
+// * xtokenPath: The directory path where the JSON file containing the X-Token is located.
+// Returns:
+// * The X-Token as a string if successfully retrieved.
+// * An error if the file does not exist, reading fails, unmarshalling fails, or the token is empty.
+func XToken(xtokenPath string) (string, error) {
+	xtokenPath = filepath.Join(xtokenPath, xtoken)
+	exist := utils.Exists(xtokenPath)
+	if !exist {
+		return "", os.ErrNotExist
+	}
+
+	token, err := os.ReadFile(xtokenPath)
+	if err != nil {
+		return "", err
+	}
+
+	var auth AuthToken
+	err = json.Unmarshal(token, &auth)
+	if err != nil {
+		return "", err
+	}
+	if auth.Token == "" {
+		return "", errors.New("x-token is empty. Please setup a token or cleanup xtokenPath")
+	}
+	return auth.Token, nil
+}

nodebuilder/state/core.go

@@ -1,6 +1,9 @@
 package state
 
 import (
+	"errors"
+	"os"
+
 	"github.com/cosmos/cosmos-sdk/crypto/keyring"
 
 	libfraud "github.com/celestiaorg/go-fraud"
@@ -30,14 +33,23 @@ func coreAccessor(
 	*modfraud.ServiceBreaker[*state.CoreAccessor, *header.ExtendedHeader],
 	error,
 ) {
-	ca, err := state.NewCoreAccessor(keyring, string(keyname), sync, corecfg.IP, corecfg.GRPCPort,
-		network.String(), opts...)
+	if corecfg.TLSEnabled {
+		// set an empty config if path is empty under `TLSEnabled=true`
+		tlsCfg := core.EmptyTLSConfig()
+		xtoken, err := core.XToken(corecfg.XTokenPath)
+		if err != nil && !errors.Is(err, os.ErrNotExist) {
+			return nil, nil, nil, err
+		}
+		opts = append(opts, state.WithTLSConfig(tlsCfg), state.WithXToken(xtoken))
+	}
+
+	ca, err := state.NewCoreAccessor(keyring, string(keyname), sync,
+		corecfg.IP, corecfg.GRPCPort, network.String(), opts...)
 
 	sBreaker := &modfraud.ServiceBreaker[*state.CoreAccessor, *header.ExtendedHeader]{
 		Service:   ca,
 		FraudType: byzantine.BadEncoding,
 		FraudServ: fraudServ,
 	}
-
 	return ca, ca, sBreaker, err
 }

state/core_access.go

@@ -2,6 +2,7 @@ package state
 
 import (
 	"context"
+	"crypto/tls"
 	"errors"
 	"fmt"
 	"sync"
@@ -20,7 +21,9 @@ import (
 	"github.com/tendermint/tendermint/proto/tendermint/crypto"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/connectivity"
+	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/metadata"
 
 	"github.com/celestiaorg/celestia-app/v3/app"
 	"github.com/celestiaorg/celestia-app/v3/app/encoding"
@@ -46,6 +49,18 @@ var (
 // to configure parameters.
 type Option func(ca *CoreAccessor)
 
+func WithTLSConfig(cfg *tls.Config) Option {
+	return func(ca *CoreAccessor) {
+		ca.tls = cfg
+	}
+}
+
+func WithXToken(xtoken string) Option {
+	return func(ca *CoreAccessor) {
+		ca.xtoken = xtoken
+	}
+}
+
 // CoreAccessor implements service over a gRPC connection
 // with a celestia-core node.
 type CoreAccessor struct {
@@ -72,6 +87,9 @@ type CoreAccessor struct {
 	grpcPort string
 	network  string
 
+	tls    *tls.Config
+	xtoken string
+
 	// these fields are mutatable and thus need to be protected by a mutex
 	lock            sync.Mutex
 	lastPayForBlob  int64
@@ -90,9 +108,7 @@ func NewCoreAccessor(
 	keyring keyring.Keyring,
 	keyname string,
 	getter libhead.Head[*header.ExtendedHeader],
-	coreIP,
-	grpcPort string,
-	network string,
+	coreIP, grpcPort, network string,
 	options ...Option,
 ) (*CoreAccessor, error) {
 	// create verifier
@@ -122,24 +138,11 @@ func (ca *CoreAccessor) Start(ctx context.Context) error {
 	}
 	ca.ctx, ca.cancel = context.WithCancel(context.Background())
 
-	// dial given celestia-core endpoint
-	endpoint := fmt.Sprintf("%s:%s", ca.coreIP, ca.grpcPort)
-	client, err := grpc.NewClient(
-		endpoint,
-		grpc.WithTransportCredentials(insecure.NewCredentials()),
-	)
+	err := ca.startGRPCClient(ctx)
 	if err != nil {
-		return err
-	}
-	// this ensures we can't start the node without core connection
-	client.Connect()
-	if !client.WaitForStateChange(ctx, connectivity.Ready) {
-		// hits the case when context is canceled
-		return fmt.Errorf("couldn't connect to core endpoint(%s): %w", endpoint, ctx.Err())
+		return fmt.Errorf("failed to start grpc client: %w", err)
 	}
 
-	ca.coreConn = client
-
 	// create the staking query client
 	ca.stakingCli = stakingtypes.NewQueryClient(ca.coreConn)
 	ca.feeGrantCli = feegrant.NewQueryClient(ca.coreConn)
@@ -601,6 +604,41 @@ func (ca *CoreAccessor) setupTxClient(ctx context.Context, keyName string) (*use
 	)
 }
 
+func (ca *CoreAccessor) startGRPCClient(ctx context.Context) error {
+	// dial given celestia-core endpoint
+	endpoint := fmt.Sprintf("%s:%s", ca.coreIP, ca.grpcPort)
+	// By default, the gRPC client is configured to handle an insecure connection.
+	// If the TLS configuration is not empty, it will be applied to the client's options.
+	// If the TLS configuration is empty but the X-Token is provided,
+	// the X-Token will be applied as an interceptor along with an empty TLS configuration.
+	opts := []grpc.DialOption{grpc.WithTransportCredentials(insecure.NewCredentials())}
+	if ca.tls != nil {
+		opts = append(opts, grpc.WithTransportCredentials(credentials.NewTLS(ca.tls)))
+	}
+
+	if interceptor := authInterceptor(ca.xtoken); interceptor != nil {
+		opts = append(opts, grpc.WithUnaryInterceptor(interceptor))
+	}
+
+	client, err := grpc.NewClient(
+		endpoint,
+		opts...,
+	)
+	if err != nil {
+		return err
+	}
+	// this ensures we can't start the node without core connection
+	client.Connect()
+	if !client.WaitForStateChange(ctx, connectivity.Ready) {
+		// hits the case when context is canceled
+		return fmt.Errorf("couldn't connect to core endpoint(%s): %w", endpoint, ctx.Err())
+	}
+	ca.coreConn = client
+
+	log.Infof("Connection with core endpoint(%s) established", endpoint)
+	return nil
+}
+
 func (ca *CoreAccessor) submitMsg(
 	ctx context.Context,
 	msg sdktypes.Msg,
@@ -657,3 +695,20 @@ func convertToSdkTxResponse(resp *user.TxResponse) *TxResponse {
 		Height: resp.Height,
 	}
 }
+
+func authInterceptor(xtoken string) grpc.UnaryClientInterceptor {
+	if xtoken == "" {
+		return nil
+	}
+	return func(
+		ctx context.Context,
+		method string,
+		req, reply interface{},
+		cc *grpc.ClientConn,
+		invoker grpc.UnaryInvoker,
+		opts ...grpc.CallOption,
+	) error {
+		ctx = metadata.AppendToOutgoingContext(ctx, "x-token", xtoken)
+		return invoker(ctx, method, req, reply, cc, opts...)
+	}
+}