beacon/light: blsync'er alternate

beacon/beaclient/client.go

@@ -0,0 +1,158 @@
+// Copyright 2023 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package beaclient
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	eth2client "github.com/attestantio/go-eth2-client"
+	eth2api "github.com/attestantio/go-eth2-client/api"
+	eth2http "github.com/attestantio/go-eth2-client/http"
+	eth2spec "github.com/attestantio/go-eth2-client/spec"
+	"github.com/ethereum/go-ethereum/beacon/types"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/rs/zerolog"
+)
+
+var (
+	beaconLightClientBootstrap        = "eth/v1/beacon/light_client/bootstrap"
+	beaconLightClientUpdate           = "eth/v1/beacon/light_client/updates"
+	beaconLightClientOptimisticUpdate = "eth/v1/beacon/light_client/optimistic_update"
+	beaconLightClientFinalityUpdate   = "eth/v1/beacon/light_client/finality_update"
+)
+
+// Client is a wrapper around the attestantio/go-eth2-client beacon api client.
+type Client struct {
+	ctx          context.Context
+	url          string
+	http         *http.Client
+	extraHeaders map[string]string
+	client       eth2client.Service
+}
+
+// NewClient creates a Client for the given server URL.
+func NewClient(ctx context.Context, server string, headers []string) (*Client, error) {
+	// Parse additional headers.
+	extraHeaders := make(map[string]string)
+	for _, h := range headers {
+		s := strings.Split(h, ":")
+		if len(s) != 2 {
+			return nil, fmt.Errorf("malformed extra header: %s", h)
+		}
+		extraHeaders[s[0]] = s[1]
+	}
+	client, err := eth2http.New(
+		ctx,
+		eth2http.WithAddress(server),
+		eth2http.WithLogLevel(zerolog.WarnLevel),
+		eth2http.WithEnforceJSON(true),
+		eth2http.WithExtraHeaders(extraHeaders),
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &Client{
+		ctx:          ctx,
+		url:          server,
+		http:         &http.Client{},
+		extraHeaders: extraHeaders,
+		client:       client,
+	}, nil
+}
+
+// Bootstrap retrieves a bootstrap object associated with the given root from
+// the beacon server.
+func (c *Client) Bootstrap(root common.Hash) (*types.Bootstrap, error) {
+	var bs types.Bootstrap
+	if err := c.fetch(fmt.Sprintf("%s/%s/%s", c.url, beaconLightClientBootstrap, root.String()), &bs); err != nil {
+		return nil, err
+	}
+	return &bs, nil
+}
+
+// GetRangeUpdate retrieves a range update for the desired periods. The updates
+// include the next sync committee and finalized header from the period.
+func (c *Client) GetRangeUpdate(start, count int) ([]*types.LightClientUpdate, error) {
+	var u []*types.LightClientUpdate
+	if err := c.fetch(fmt.Sprintf("%s/%s?start_period=%d&count=%d", c.url, beaconLightClientUpdate, start, count), &u); err != nil {
+		return nil, err
+	}
+	return u, nil
+}
+
+// GetOptimisticUpdate retrieves the latest available optimistic update from the
+// beacon api server.
+func (c *Client) GetOptimisticUpdate() (*types.LightClientUpdate, error) {
+	var u types.LightClientUpdate
+	if err := c.fetch(fmt.Sprintf("%s/%s", c.url, beaconLightClientOptimisticUpdate), &u); err != nil {
+		return nil, err
+	}
+	return &u, nil
+}
+
+// GetFinalityUpdate retrieves the latest available finality update from the
+// beacon api server.
+func (c *Client) GetFinalityUpdate() (*types.LightClientUpdate, error) {
+	var u types.LightClientUpdate
+	if err := c.fetch(fmt.Sprintf("%s/%s", c.url, beaconLightClientFinalityUpdate), &u); err != nil {
+		return nil, err
+	}
+	return &u, nil
+}
+
+// GetBlock retrieves the full beacon block associated with the given root.
+func (c *Client) GetBlock(root common.Hash) (*eth2spec.VersionedSignedBeaconBlock, error) {
+	provider, ok := c.client.(eth2client.SignedBeaconBlockProvider)
+	if !ok {
+		return nil, fmt.Errorf("beacon server does not support retrieving blocks")
+	}
+	resp, err := provider.SignedBeaconBlock(c.ctx, &eth2api.SignedBeaconBlockOpts{Block: root.String()})
+	if err != nil {
+		return nil, fmt.Errorf("failed http request: %w", err)
+	}
+	return resp.Data, nil
+}
+
+func (c *Client) fetch(url string, val any) error {
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return err
+	}
+	for k, v := range c.extraHeaders {
+		req.Header.Set(k, v)
+	}
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return fmt.Errorf("failed http request: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("failed http request: status %d", resp.StatusCode)
+	}
+	b, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response: %w", err)
+	}
+	if err := json.Unmarshal(b, val); err != nil {
+		return fmt.Errorf("failed to unmarshal data: %v", err)
+	}
+	return nil
+}