Add REST implementation for Validator's PrepareBeaconProposer (#11784)

* Add REST implementation for Validator's PrepareBeaconProposer

* Change fee recipients

* Handle error in a better way

* Move endpoint into constant

Co-authored-by: Radosław Kapka <rkapka@wp.pl>

validator/client/beacon-api/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
         "get_beacon_block.go",
         "index.go",
         "json_rest_handler.go",
+        "prepare_beacon_proposer.go",
         "propose_beacon_block.go",
         "state_validators.go",
         "status.go",
@@ -56,6 +57,7 @@ go_test(
         "get_beacon_block_test.go",
         "index_test.go",
         "json_rest_handler_test.go",
+        "prepare_beacon_proposer_test.go",
         "propose_beacon_block_altair_test.go",
         "propose_beacon_block_bellatrix_test.go",
         "propose_beacon_block_blinded_bellatrix_test.go",

validator/client/beacon-api/beacon_api_validator_client.go

@@ -120,13 +120,8 @@ func (c *beaconApiValidatorClient) MultipleValidatorStatus(ctx context.Context,
 	panic("beaconApiValidatorClient.MultipleValidatorStatus is not implemented. To use a fallback client, create this validator with NewBeaconApiValidatorClientWithFallback instead.")
 }
 
-func (c *beaconApiValidatorClient) PrepareBeaconProposer(ctx context.Context, in *ethpb.PrepareBeaconProposerRequest) (*empty.Empty, error) {
-	if c.fallbackClient != nil {
-		return c.fallbackClient.PrepareBeaconProposer(ctx, in)
-	}
-
-	// TODO: Implement me
-	panic("beaconApiValidatorClient.PrepareBeaconProposer is not implemented. To use a fallback client, create this validator with NewBeaconApiValidatorClientWithFallback instead.")
+func (c *beaconApiValidatorClient) PrepareBeaconProposer(_ context.Context, in *ethpb.PrepareBeaconProposerRequest) (*empty.Empty, error) {
+	return new(empty.Empty), c.prepareBeaconProposer(in.Recipients)
 }
 
 func (c *beaconApiValidatorClient) ProposeAttestation(ctx context.Context, in *ethpb.Attestation) (*ethpb.AttestResponse, error) {

validator/client/beacon-api/prepare_beacon_proposer.go

@@ -0,0 +1,33 @@
+package beacon_api
+
+import (
+	"bytes"
+	"encoding/json"
+	"strconv"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v3/beacon-chain/rpc/apimiddleware"
+	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
+)
+
+func (c *beaconApiValidatorClient) prepareBeaconProposer(recipients []*ethpb.PrepareBeaconProposerRequest_FeeRecipientContainer) error {
+	jsonRecipients := make([]*apimiddleware.FeeRecipientJson, len(recipients))
+	for index, recipient := range recipients {
+		jsonRecipients[index] = &apimiddleware.FeeRecipientJson{
+			FeeRecipient:   hexutil.Encode(recipient.FeeRecipient),
+			ValidatorIndex: strconv.FormatUint(uint64(recipient.ValidatorIndex), 10),
+		}
+	}
+
+	marshalledJsonRecipients, err := json.Marshal(jsonRecipients)
+	if err != nil {
+		return errors.Wrap(err, "failed to marshal recipients")
+	}
+
+	if _, err := c.jsonRestHandler.PostRestJson("/eth/v1/validator/prepare_beacon_proposer", nil, bytes.NewBuffer(marshalledJsonRecipients), nil); err != nil {
+		return errors.Wrap(err, "failed to send POST data to REST endpoint")
+	}
+
+	return nil
+}

validator/client/beacon-api/prepare_beacon_proposer_test.go

@@ -0,0 +1,103 @@
+package beacon_api
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/golang/mock/gomock"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v3/beacon-chain/rpc/apimiddleware"
+	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v3/testing/assert"
+	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v3/validator/client/beacon-api/mock"
+)
+
+const prepareBeaconProposerTestEndpoint = "/eth/v1/validator/prepare_beacon_proposer"
+
+func TestPrepareBeaconProposer_Valid(t *testing.T) {
+	const feeRecipient1 = "0xca008b199c03a2a2f6bc2ed52d6404c4d8510b35"
+	const feeRecipient2 = "0x8145d80111309e4621ed7632319664ac440b0198"
+	const feeRecipient3 = "0x085f2adb1295821838910be402b3c8cdc118bd86"
+
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	jsonRecipients := []*apimiddleware.FeeRecipientJson{
+		{
+			ValidatorIndex: "1",
+			FeeRecipient:   feeRecipient1,
+		},
+		{
+			ValidatorIndex: "2",
+			FeeRecipient:   feeRecipient2,
+		},
+		{
+			ValidatorIndex: "3",
+			FeeRecipient:   feeRecipient3,
+		},
+	}
+
+	marshalledJsonRecipients, err := json.Marshal(jsonRecipients)
+	require.NoError(t, err)
+
+	jsonRestHandler := mock.NewMockjsonRestHandler(ctrl)
+	jsonRestHandler.EXPECT().PostRestJson(
+		prepareBeaconProposerTestEndpoint,
+		nil,
+		bytes.NewBuffer(marshalledJsonRecipients),
+		nil,
+	).Return(
+		nil,
+		nil,
+	).Times(1)
+
+	decodedFeeRecipient1, err := hexutil.Decode(feeRecipient1)
+	require.NoError(t, err)
+	decodedFeeRecipient2, err := hexutil.Decode(feeRecipient2)
+	require.NoError(t, err)
+	decodedFeeRecipient3, err := hexutil.Decode(feeRecipient3)
+	require.NoError(t, err)
+
+	protoRecipients := []*ethpb.PrepareBeaconProposerRequest_FeeRecipientContainer{
+		{
+			ValidatorIndex: 1,
+			FeeRecipient:   decodedFeeRecipient1,
+		},
+		{
+			ValidatorIndex: 2,
+			FeeRecipient:   decodedFeeRecipient2,
+		},
+		{
+			ValidatorIndex: 3,
+			FeeRecipient:   decodedFeeRecipient3,
+		},
+	}
+
+	validatorClient := &beaconApiValidatorClient{jsonRestHandler: jsonRestHandler}
+	err = validatorClient.prepareBeaconProposer(protoRecipients)
+	require.NoError(t, err)
+}
+
+func TestPrepareBeaconProposer_BadRequest(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	jsonRestHandler := mock.NewMockjsonRestHandler(ctrl)
+	jsonRestHandler.EXPECT().PostRestJson(
+		prepareBeaconProposerTestEndpoint,
+		nil,
+		gomock.Any(),
+		nil,
+	).Return(
+		nil,
+		errors.New("foo error"),
+	).Times(1)
+
+	validatorClient := &beaconApiValidatorClient{jsonRestHandler: jsonRestHandler}
+	err := validatorClient.prepareBeaconProposer(nil)
+	assert.ErrorContains(t, "failed to send POST data to REST endpoint", err)
+	assert.ErrorContains(t, "foo error", err)
+}