erigon-pulse/erigon-lib/chain/chain_db.go

/*
   Copyright 2021 Erigon contributors

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package chain

import (
	"encoding/binary"
	"encoding/json"
	"fmt"

	"github.com/ledgerwatch/erigon-lib/common"
	"github.com/ledgerwatch/erigon-lib/kv"
)

// GetConfig retrieves the consensus settings based on the given genesis hash.
func GetConfig(db kv.Getter, buf []byte) (*Config, error) {
	hash, err := CanonicalHash(db, 0, buf)
	if err != nil {
		return nil, fmt.Errorf("failed ReadCanonicalHash: %w", err)
	}
	if hash == nil {
		return nil, nil
	}
	data, err := db.GetOne(kv.ConfigTable, hash)
	if err != nil {
		return nil, err
	}
	if len(data) == 0 {
		return nil, nil
	}
	var config Config
	if err := json.Unmarshal(data, &config); err != nil {
		return nil, fmt.Errorf("invalid chain config JSON: %s, %w", data, err)
	}
	return &config, nil
}

func CanonicalHash(db kv.Getter, number uint64, buf []byte) ([]byte, error) {
	buf = common.EnsureEnoughSize(buf, 8)
	binary.BigEndian.PutUint64(buf, number)
	data, err := db.GetOne(kv.HeaderCanonical, buf)
	if err != nil {
		return nil, fmt.Errorf("failed CanonicalHash: %w, number=%d", err, number)
	}
	if len(data) == 0 {
		return nil, nil
	}

	return data, nil
}

// HeadHeaderHash retrieves the hash of the current canonical head header.
func HeadHeaderHash(db kv.Getter) ([]byte, error) {
	data, err := db.GetOne(kv.HeadHeaderKey, []byte(kv.HeadHeaderKey))
	if err != nil {
		return nil, fmt.Errorf("ReadHeadHeaderHash failed: %w", err)
	}
	return data, nil
}

func CurrentBlockNumber(db kv.Getter) (*uint64, error) {
	headHash, err := HeadHeaderHash(db)
	if err != nil {
		return nil, err
	}
	return HeaderNumber(db, headHash)
}

// HeaderNumber returns the header number assigned to a hash.
func HeaderNumber(db kv.Getter, hash []byte) (*uint64, error) {
	data, err := db.GetOne(kv.HeaderNumber, hash)
	if err != nil {
		return nil, fmt.Errorf("ReadHeaderNumber failed: %w", err)
	}
	if len(data) == 0 {
		return nil, nil
	}
	if len(data) != 8 {
		return nil, fmt.Errorf("ReadHeaderNumber got wrong data len: %d", len(data))
	}
	number := binary.BigEndian.Uint64(data)
	return &number, nil
}