path: root/les/odr_requests.go

// Copyright 2016 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 light implements on-demand retrieval capable state and chain objects
// for the Ethereum Light Client.
package les

import (
    "encoding/binary"
    "errors"
    "fmt"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/light"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/trie"
)

var (
    errInvalidMessageType  = errors.New("invalid message type")
    errMultipleEntries     = errors.New("multiple response entries")
    errHeaderUnavailable   = errors.New("header unavailable")
    errTxHashMismatch      = errors.New("transaction hash mismatch")
    errUncleHashMismatch   = errors.New("uncle hash mismatch")
    errReceiptHashMismatch = errors.New("receipt hash mismatch")
    errDataHashMismatch    = errors.New("data hash mismatch")
    errCHTHashMismatch     = errors.New("cht hash mismatch")
)

type LesOdrRequest interface {
    GetCost(*peer) uint64
    CanSend(*peer) bool
    Request(uint64, *peer) error
    Validate(ethdb.Database, *Msg) error
}

func LesRequest(req light.OdrRequest) LesOdrRequest {
    switch r := req.(type) {
    case *light.BlockRequest:
        return (*BlockRequest)(r)
    case *light.ReceiptsRequest:
        return (*ReceiptsRequest)(r)
    case *light.TrieRequest:
        return (*TrieRequest)(r)
    case *light.CodeRequest:
        return (*CodeRequest)(r)
    case *light.ChtRequest:
        return (*ChtRequest)(r)
    default:
        return nil
    }
}

// BlockRequest is the ODR request type for block bodies
type BlockRequest light.BlockRequest

// GetCost returns the cost of the given ODR request according to the serving
// peer's cost table (implementation of LesOdrRequest)
func (r *BlockRequest) GetCost(peer *peer) uint64 {
    return peer.GetRequestCost(GetBlockBodiesMsg, 1)
}

// CanSend tells if a certain peer is suitable for serving the given request
func (r *BlockRequest) CanSend(peer *peer) bool {
    return peer.HasBlock(r.Hash, r.Number)
}

// Request sends an ODR request to the LES network (implementation of LesOdrRequest)
func (r *BlockRequest) Request(reqID uint64, peer *peer) error {
    peer.Log().Debug("Requesting block body", "hash", r.Hash)
    return peer.RequestBodies(reqID, r.GetCost(peer), []common.Hash{r.Hash})
}

// Valid processes an ODR request reply message from the LES network
// returns true and stores results in memory if the message was a valid reply
// to the request (implementation of LesOdrRequest)
func (r *BlockRequest) Validate(db ethdb.Database, msg *Msg) error {
    log.Debug("Validating block body", "hash", r.Hash)

    // Ensure we have a correct message with a single block body
    if msg.MsgType != MsgBlockBodies {
        return errInvalidMessageType
    }
    bodies := msg.Obj.([]*types.Body)
    if len(bodies) != 1 {
        return errMultipleEntries
    }
    body := bodies[0]

    // Retrieve our stored header and validate block content against it
    header := core.GetHeader(db, r.Hash, r.Number)
    if header == nil {
        return errHeaderUnavailable
    }
    if header.TxHash != types.DeriveSha(types.Transactions(body.Transactions)) {
        return errTxHashMismatch
    }
    if header.UncleHash != types.CalcUncleHash(body.Uncles) {
        return errUncleHashMismatch
    }
    // Validations passed, encode and store RLP
    data, err := rlp.EncodeToBytes(body)
    if err != nil {
        return err
    }
    r.Rlp = data
    return nil
}

// ReceiptsRequest is the ODR request type for block receipts by block hash
type ReceiptsRequest light.ReceiptsRequest

// GetCost returns the cost of the given ODR request according to the serving
// peer's cost table (implementation of LesOdrRequest)
func (r *ReceiptsRequest) GetCost(peer *peer) uint64 {
    return peer.GetRequestCost(GetReceiptsMsg, 1)
}

// CanSend tells if a certain peer is suitable for serving the given request
func (r *ReceiptsRequest) CanSend(peer *peer) bool {
    return peer.HasBlock(r.Hash, r.Number)
}

// Request sends an ODR request to the LES network (implementation of LesOdrRequest)
func (r *ReceiptsRequest) Request(reqID uint64, peer *peer) error {
    peer.Log().Debug("Requesting block receipts", "hash", r.Hash)
    return peer.RequestReceipts(reqID, r.GetCost(peer), []common.Hash{r.Hash})
}

// Valid processes an ODR request reply message from the LES network
// returns true and stores results in memory if the message was a valid reply
// to the request (implementation of LesOdrRequest)
func (r *ReceiptsRequest) Validate(db ethdb.Database, msg *Msg) error {
    log.Debug("Validating block receipts", "hash", r.Hash)

    // Ensure we have a correct message with a single block receipt
    if msg.MsgType != MsgReceipts {
        return errInvalidMessageType
    }
    receipts := msg.Obj.([]types.Receipts)
    if len(receipts) != 1 {
        return errMultipleEntries
    }
    receipt := receipts[0]

    // Retrieve our stored header and validate receipt content against it
    header := core.GetHeader(db, r.Hash, r.Number)
    if header == nil {
        return errHeaderUnavailable
    }
    if header.ReceiptHash != types.DeriveSha(receipt) {
        return errReceiptHashMismatch
    }
    // Validations passed, store and return
    r.Receipts = receipt
    return nil
}

type ProofReq struct {
    BHash       common.Hash
    AccKey, Key []byte
    FromLevel   uint
}

// ODR request type for state/storage trie entries, see LesOdrRequest interface
type TrieRequest light.TrieRequest

// GetCost returns the cost of the given ODR request according to the serving
// peer's cost table (implementation of LesOdrRequest)
func (r *TrieRequest) GetCost(peer *peer) uint64 {
    return peer.GetRequestCost(GetProofsMsg, 1)
}

// CanSend tells if a certain peer is suitable for serving the given request
func (r *TrieRequest) CanSend(peer *peer) bool {
    return peer.HasBlock(r.Id.BlockHash, r.Id.BlockNumber)
}

// Request sends an ODR request to the LES network (implementation of LesOdrRequest)
func (r *TrieRequest) Request(reqID uint64, peer *peer) error {
    peer.Log().Debug("Requesting trie proof", "root", r.Id.Root, "key", r.Key)
    req := &ProofReq{
        BHash:  r.Id.BlockHash,
        AccKey: r.Id.AccKey,
        Key:    r.Key,
    }
    return peer.RequestProofs(reqID, r.GetCost(peer), []*ProofReq{req})
}

// Valid processes an ODR request reply message from the LES network
// returns true and stores results in memory if the message was a valid reply
// to the request (implementation of LesOdrRequest)
func (r *TrieRequest) Validate(db ethdb.Database, msg *Msg) error {
    log.Debug("Validating trie proof", "root", r.Id.Root, "key", r.Key)

    // Ensure we have a correct message with a single proof
    if msg.MsgType != MsgProofs {
        return errInvalidMessageType
    }
    proofs := msg.Obj.([][]rlp.RawValue)
    if len(proofs) != 1 {
        return errMultipleEntries
    }
    // Verify the proof and store if checks out
    if _, err := trie.VerifyProof(r.Id.Root, r.Key, proofs[0]); err != nil {
        return fmt.Errorf("merkle proof verification failed: %v", err)
    }
    r.Proof = proofs[0]
    return nil
}

type CodeReq struct {
    BHash  common.Hash
    AccKey []byte
}

// ODR request type for node data (used for retrieving contract code), see LesOdrRequest interface
type CodeRequest light.CodeRequest

// GetCost returns the cost of the given ODR request according to the serving
// peer's cost table (implementation of LesOdrRequest)
func (r *CodeRequest) GetCost(peer *peer) uint64 {
    return peer.GetRequestCost(GetCodeMsg, 1)
}

// CanSend tells if a certain peer is suitable for serving the given request
func (r *CodeRequest) CanSend(peer *peer) bool {
    return peer.HasBlock(r.Id.BlockHash, r.Id.BlockNumber)
}

// Request sends an ODR request to the LES network (implementation of LesOdrRequest)
func (r *CodeRequest) Request(reqID uint64, peer *peer) error {
    peer.Log().Debug("Requesting code data", "hash", r.Hash)
    req := &CodeReq{
        BHash:  r.Id.BlockHash,
        AccKey: r.Id.AccKey,
    }
    return peer.RequestCode(reqID, r.GetCost(peer), []*CodeReq{req})
}

// Valid processes an ODR request reply message from the LES network
// returns true and stores results in memory if the message was a valid reply
// to the request (implementation of LesOdrRequest)
func (r *CodeRequest) Validate(db ethdb.Database, msg *Msg) error {
    log.Debug("Validating code data", "hash", r.Hash)

    // Ensure we have a correct message with a single code element
    if msg.MsgType != MsgCode {
        return errInvalidMessageType
    }
    reply := msg.Obj.([][]byte)
    if len(reply) != 1 {
        return errMultipleEntries
    }
    data := reply[0]

    // Verify the data and store if checks out
    if hash := crypto.Keccak256Hash(data); r.Hash != hash {
        return errDataHashMismatch
    }
    r.Data = data
    return nil
}

type ChtReq struct {
    ChtNum, BlockNum, FromLevel uint64
}

type ChtResp struct {
    Header *types.Header
    Proof  []rlp.RawValue
}

// ODR request type for requesting headers by Canonical Hash Trie, see LesOdrRequest interface
type ChtRequest light.ChtRequest

// GetCost returns the cost of the given ODR request according to the serving
// peer's cost table (implementation of LesOdrRequest)
func (r *ChtRequest) GetCost(peer *peer) uint64 {
    return peer.GetRequestCost(GetHeaderProofsMsg, 1)
}

// CanSend tells if a certain peer is suitable for serving the given request
func (r *ChtRequest) CanSend(peer *peer) bool {
    peer.lock.RLock()
    defer peer.lock.RUnlock()

    return r.ChtNum <= (peer.headInfo.Number-light.ChtConfirmations)/light.ChtFrequency
}

// Request sends an ODR request to the LES network (implementation of LesOdrRequest)
func (r *ChtRequest) Request(reqID uint64, peer *peer) error {
    peer.Log().Debug("Requesting CHT", "cht", r.ChtNum, "block", r.BlockNum)
    req := &ChtReq{
        ChtNum:   r.ChtNum,
        BlockNum: r.BlockNum,
    }
    return peer.RequestHeaderProofs(reqID, r.GetCost(peer), []*ChtReq{req})
}

// Valid processes an ODR request reply message from the LES network
// returns true and stores results in memory if the message was a valid reply
// to the request (implementation of LesOdrRequest)
func (r *ChtRequest) Validate(db ethdb.Database, msg *Msg) error {
    log.Debug("Validating CHT", "cht", r.ChtNum, "block", r.BlockNum)

    // Ensure we have a correct message with a single proof element
    if msg.MsgType != MsgHeaderProofs {
        return errInvalidMessageType
    }
    proofs := msg.Obj.([]ChtResp)
    if len(proofs) != 1 {
        return errMultipleEntries
    }
    proof := proofs[0]

    // Verify the CHT
    var encNumber [8]byte
    binary.BigEndian.PutUint64(encNumber[:], r.BlockNum)

    value, err := trie.VerifyProof(r.ChtRoot, encNumber[:], proof.Proof)
    if err != nil {
        return err
    }
    var node light.ChtNode
    if err := rlp.DecodeBytes(value, &node); err != nil {
        return err
    }
    if node.Hash != proof.Header.Hash() {
        return errCHTHashMismatch
    }
    // Verifications passed, store and return
    r.Header = proof.Header
    r.Proof = proof.Proof
    r.Td = node.Td

    return nil
}