some basic validation of ethereum deposit data file

cli/internal/cmd/sign.go

@@ -45,7 +45,8 @@ func Sign(cmd *cobra.Command, _ []string) {
 	}
 
 	log := shared.QuietLogger{Quiet: shortFlag}
-	signingOutput, err := cli.Sign(shared.Uniq(append(args, operatorFlag...)), depositData, log)
+	// TODO: this should probably sign something more than just the deposit data root
+	signingOutput, err := cli.Sign(shared.Uniq(append(args, operatorFlag...)), depositData.DepositDataRoot, log)
 	if err != nil {
 		shared.Exit(fmt.Sprintf("%v", err))
 	}

cli/internal/cmd/sign_test.go

@@ -1,18 +1,21 @@
 package cmd
 
 import (
+	"encoding/json"
+	"math/big"
 	"os"
 	"path"
 	"strings"
 	"testing"
 
+	"github.com/randa-mu/ssv-dkg/shared/api"
 	"github.com/stretchr/testify/require"
 )
 
 func TestSignCommand(t *testing.T) {
 	tmp := t.TempDir()
 	filepath := path.Join(tmp, "testfile")
-	createJunkFile(t, filepath)
+	createdUnsignedDepositData(t, filepath)
 
 	tests := []struct {
 		name        string
@@ -96,10 +99,22 @@ func TestSignCommand(t *testing.T) {
 	}
 }
 
-func createJunkFile(t *testing.T, filepath string) {
+func createdUnsignedDepositData(t *testing.T, filepath string) {
+	data := api.UnsignedDepositData{
+		WithdrawalCredentials: []byte("hello world"),
+		DepositDataRoot:       []byte("hello world"),
+		DepositMessageRoot:    []byte("hello world"),
+		Amount:                api.BigInt{Int: *big.NewInt(1)},
+		ForkVersion:           "somefork",
+		NetworkName:           "somenetwork",
+		DepositCLIVersion:     "somecli",
+	}
+
+	bytes, err := json.Marshal(data)
+	require.NoError(t, err)
 	file, err := os.Create(filepath)
 	require.NoError(t, err)
-	_, err = file.Write([]byte("hello"))
+	_, err = file.Write(bytes)
 	require.NoError(t, err)
 	err = file.Close()
 	require.NoError(t, err)

shared/api/cli.go

@@ -1,19 +1,20 @@
 package api
 
 import (
+	"fmt"
 	"math/big"
 
 	"github.com/randa-mu/ssv-dkg/shared/crypto"
 )
 
 type UnsignedDepositData struct {
-	WithdrawalCredentials []byte  `json:"withdrawal_credentials"`
-	DepositDataRoot       []byte  `json:"deposit_data_root"`
-	DepositMessageRoot    []byte  `json:"deposit_message_root,omitempty"`
-	Amount                big.Int `json:"amount,omitempty"`
-	ForkVersion           string  `json:"fork_version,omitempty"`
-	NetworkName           string  `json:"network_name,omitempty"`
-	DepositCLIVersion     string  `json:"deposit_cli_version,omitempty"`
+	WithdrawalCredentials []byte `json:"withdrawal_credentials"`
+	DepositDataRoot       []byte `json:"deposit_data_root"`
+	DepositMessageRoot    []byte `json:"deposit_message_root,omitempty"`
+	Amount                BigInt `json:"amount,omitempty"`
+	ForkVersion           string `json:"fork_version,omitempty"`
+	NetworkName           string `json:"network_name,omitempty"`
+	DepositCLIVersion     string `json:"deposit_cli_version,omitempty"`
 }
 
 type SignedDepositData struct {
@@ -38,3 +39,25 @@ type OperatorResponse struct {
 	Identity crypto.Identity
 	Response SignResponse
 }
+
+type BigInt struct {
+	big.Int
+}
+
+// MarshalJSON intentionally uses a value pointer or things go wrong
+func (b BigInt) MarshalJSON() ([]byte, error) {
+	return []byte(b.String()), nil
+}
+
+func (b *BigInt) UnmarshalJSON(p []byte) error {
+	if string(p) == "null" {
+		return nil
+	}
+	var z big.Int
+	_, ok := z.SetString(string(p), 10)
+	if !ok {
+		return fmt.Errorf("not a valid big integer: %s", p)
+	}
+	b.Int = z
+	return nil
+}