prysm-pulse/beacon-chain/rpc/apimiddleware/custom_hooks.go

package apimiddleware

import (
	"bytes"
	"encoding/json"
	"io/ioutil"
	"net/http"

	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/pkg/errors"
	"github.com/prysmaticlabs/prysm/shared/bytesutil"
	"github.com/prysmaticlabs/prysm/shared/gateway"
)

// https://ethereum.github.io/eth2.0-APIs/#/Beacon/submitPoolAttestations expects posting a top-level array.
// We make it more proto-friendly by wrapping it in a struct with a 'data' field.
func wrapAttestationsArray(endpoint gateway.Endpoint, _ http.ResponseWriter, req *http.Request) gateway.ErrorJson {
	if _, ok := endpoint.PostRequest.(*submitAttestationRequestJson); ok {
		atts := make([]*attestationJson, 0)
		if err := json.NewDecoder(req.Body).Decode(&atts); err != nil {
			e := errors.Wrapf(err, "could not decode attestations array")
			return &gateway.DefaultErrorJson{Message: e.Error(), Code: http.StatusInternalServerError}
		}
		j := &submitAttestationRequestJson{Data: atts}
		b, err := json.Marshal(j)
		if err != nil {
			e := errors.Wrapf(err, "could not marshal wrapped attestations array")
			return &gateway.DefaultErrorJson{Message: e.Error(), Code: http.StatusInternalServerError}
		}
		req.Body = ioutil.NopCloser(bytes.NewReader(b))
	}
	return nil
}

// Posted graffiti needs to have length of 32 bytes, but client is allowed to send data of any length.
func prepareGraffiti(endpoint gateway.Endpoint, _ http.ResponseWriter, _ *http.Request) gateway.ErrorJson {
	if block, ok := endpoint.PostRequest.(*beaconBlockContainerJson); ok {
		b := bytesutil.ToBytes32([]byte(block.Message.Body.Graffiti))
		block.Message.Body.Graffiti = hexutil.Encode(b[:])
	}
	return nil
}