peer.go

// Copyright 2015 The CortexTheseus Authors
// This file is part of the CortexTheseus library.
//
// The CortexTheseus 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 CortexTheseus 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 CortexTheseus library. If not, see <http://www.gnu.org/licenses/>.

package ctxc

import (
	"errors"
	"fmt"
	"math/big"
	"sync"
	"time"

	"github.com/CortexFoundation/CortexTheseus/common"
	"github.com/CortexFoundation/CortexTheseus/core/types"
	"github.com/CortexFoundation/CortexTheseus/ctxc/protocols/ctxc"
	"github.com/CortexFoundation/CortexTheseus/p2p"
	"github.com/CortexFoundation/CortexTheseus/rlp"
	mapset "github.com/deckarep/golang-set/v2"
)

var (
	errClosed            = errors.New("peer set is closed")
	errAlreadyRegistered = errors.New("peer is already registered")
	errNotRegistered     = errors.New("peer is not registered")
)

const (
	maxKnownTxs    = 32768 // Maximum transactions hashes to keep in the known list (prevent DOS)
	maxKnownBlocks = 1024  // Maximum block hashes to keep in the known list (prevent DOS)

	// maxQueuedTxs is the maximum number of transactions to queue up before dropping
	// older broadcasts.
	maxQueuedTxs = 4096

	// maxQueuedTxAnns is the maximum number of transaction announcements to queue up
	// before dropping older announcements.
	maxQueuedTxAnns = 4096

	// maxQueuedBlocks is the maximum number of block propagations to queue up before
	// dropping broadcasts. There's not much point in queueing stale blocks, so a few
	// that might cover uncles should be enough.
	maxQueuedBlocks = 4

	// maxQueuedBlockAnns is the maximum number of block announcements to queue up before
	// dropping broadcasts. Similarly to block propagations, there's no point to queue
	// above some healthy uncle limit, so use that.
	maxQueuedBlockAnns = 4
)

// max is a helper function which returns the larger of the two given integers.
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

// PeerInfo represents a short summary of the Cortex sub-protocol metadata known
// about a connected peer.
type PeerInfo struct {
	Version    uint     `json:"version"`    // Cortex protocol version negotiated
	Difficulty *big.Int `json:"difficulty"` // Total difficulty of the peer's blockchain
	Head       string   `json:"head"`       // SHA3 hash of the peer's best owned block
}

// propEvent is a block propagation, waiting for its turn in the broadcast queue.
type propEvent struct {
	block *types.Block
	td    *big.Int
}

type peer struct {
	id string

	*p2p.Peer
	rw p2p.MsgReadWriter

	version  uint        // Protocol version negotiated
	syncDrop *time.Timer // Timed connection dropper if sync progress isn't validated in time

	head common.Hash
	td   *big.Int

	knownBlocks     *knownCache                          // Set of block hashes known to be known by this peer
	queuedBlocks    chan *propEvent                      // Queue of blocks to broadcast to the peer
	queuedBlockAnns chan *types.Block                    // Queue of blocks to announce to the peer
	knownTxs        *knownCache                          // Set of transaction hashes known to be known by this peer
	txBroadcast     chan []common.Hash                   // Channel used to queue transaction propagation requests
	txAnnounce      chan []common.Hash                   // Channel used to queue transaction announcement requests
	getPooledTx     func(common.Hash) *types.Transaction // Callback used to retrieve transaction from txpool

	reqDispatch chan *request  // Dispatch channel to send requests and track then until fulfilment
	reqCancel   chan *cancel   // Dispatch channel to cancel pending requests and untrack them
	resDispatch chan *response // Dispatch channel to fulfil pending requests and untrack them

	term chan struct{} // Termination channel to stop the broadcaster
	lock sync.RWMutex
}

func newPeer(version uint, p *p2p.Peer, rw p2p.MsgReadWriter, getPooledTx func(hash common.Hash) *types.Transaction) *peer {
	peer := &peer{
		Peer:            p,
		rw:              rw,
		version:         version,
		id:              p.ID().String(), //fmt.Sprintf("%x", p.ID().Bytes()[:8]),
		knownTxs:        newKnownCache(maxKnownTxs),
		knownBlocks:     newKnownCache(maxKnownBlocks),
		queuedBlocks:    make(chan *propEvent, maxQueuedBlocks),
		queuedBlockAnns: make(chan *types.Block, maxQueuedBlockAnns),
		txBroadcast:     make(chan []common.Hash),
		txAnnounce:      make(chan []common.Hash),
		reqDispatch:     make(chan *request),
		reqCancel:       make(chan *cancel),
		resDispatch:     make(chan *response),
		getPooledTx:     getPooledTx,
		term:            make(chan struct{}),
	}

	go peer.broadcastBlocks()
	go peer.broadcastTransactions()
	if peer.version >= ctxc65 {
		go peer.announceTransactions()
	}
	//go peer.dispatcher()

	return peer
}

// close signals the broadcast goroutine to terminate.
func (p *peer) close() {
	close(p.term)
}

// Version retrieves the peer's negoatiated `eth` protocol version.
func (p *peer) Version() uint {
	return p.version
}

// Info gathers and returns a collection of metadata known about a peer.
func (p *peer) Info() *PeerInfo {
	hash, td := p.Head()

	return &PeerInfo{
		Version:    p.version,
		Difficulty: td,
		Head:       hash.Hex(),
	}
}

// Head retrieves a copy of the current head hash and total difficulty of the
// peer.
func (p *peer) Head() (hash common.Hash, td *big.Int) {
	p.lock.RLock()
	defer p.lock.RUnlock()

	copy(hash[:], p.head[:])
	return hash, new(big.Int).Set(p.td)
}

// SetHead updates the head hash and total difficulty of the peer.
func (p *peer) SetHead(hash common.Hash, td *big.Int) {
	p.lock.Lock()
	defer p.lock.Unlock()

	copy(p.head[:], hash[:])
	p.td.Set(td)
}

// KnownBlock returns whether peer is known to already have a block.
func (p *peer) KnownBlock(hash common.Hash) bool {
	return p.knownBlocks.Contains(hash)
}

// KnownTransaction returns whether peer is known to already have a transaction.
func (p *peer) KnownTransaction(hash common.Hash) bool {
	return p.knownTxs.Contains(hash)
}

// MarkBlock marks a block as known for the peer, ensuring that the block will
// never be propagated to this particular peer.
func (p *peer) MarkBlock(hash common.Hash) {
	// If we reached the memory allowance, drop a previously known block hash
	p.knownBlocks.Add(hash)
}

// MarkTransaction marks a transaction as known for the peer, ensuring that it
// will never be propagated to this particular peer.
func (p *peer) MarkTransaction(hash common.Hash) {
	// If we reached the memory allowance, drop a previously known transaction hash
	p.knownTxs.Add(hash)
}

// SendTransactions64 sends transactions to the peer and includes the hashes
// in its transaction hash set for future reference.
//
// This method is legacy support for initial transaction exchange in ctxc/64 and
// prior. For ctxc/65 and higher use SendPooledTransactionHashes.
func (p *peer) SendTransactions64(txs types.Transactions) error {
	return p.sendTransactions(txs)
}

// sendTransactions sends transactions to the peer and includes the hashes
// in its transaction hash set for future reference.
//
// This method is a helper used by the async transaction sender. Don't call it
// directly as the queueing (memory) and transmission (bandwidth) costs should
// not be managed directly.
func (p *peer) sendTransactions(txs types.Transactions) error {
	// Mark all the transactions as known, but ensure we don't overflow our limits
	for _, tx := range txs {
		p.knownTxs.Add(tx.Hash())
	}
	return p2p.Send(p.rw, ctxc.TransactionMsg, txs)
}

// AsyncSendTransactions queues a list of transactions (by hash) to eventually
// propagate to a remote peer. The number of pending sends are capped (new ones
// will force old sends to be dropped)
func (p *peer) AsyncSendTransactions(hashes []common.Hash) {
	select {
	case p.txBroadcast <- hashes:
		// Mark all the transactions as known, but ensure we don't overflow our limits
		p.knownTxs.Add(hashes...)
	case <-p.term:
		p.Log().Debug("Dropping transaction propagation", "count", len(hashes))
	}
}

// sendPooledTransactionHashes sends transaction hashes to the peer and includes
// them in its transaction hash set for future reference.
//
// This method is a helper used by the async transaction announcer. Don't call it
// directly as the queueing (memory) and transmission (bandwidth) costs should
// not be managed directly.
func (p *peer) sendPooledTransactionHashes(hashes []common.Hash) error {
	// Mark all the transactions as known, but ensure we don't overflow our limits
	p.knownTxs.Add(hashes...)
	return p2p.Send(p.rw, ctxc.NewPooledTransactionHashesMsg, hashes)
}

// AsyncSendPooledTransactionHashes queues a list of transactions hashes to eventually
// announce to a remote peer.  The number of pending sends are capped (new ones
// will force old sends to be dropped)
func (p *peer) AsyncSendPooledTransactionHashes(hashes []common.Hash) {
	select {
	case p.txAnnounce <- hashes:
		// Mark all the transactions as known, but ensure we don't overflow our limits
		p.knownTxs.Add(hashes...)
	case <-p.term:
		p.Log().Debug("Dropping transaction announcement", "count", len(hashes))
	}
}

// SendPooledTransactionsRLP sends requested transactions to the peer and adds the
// hashes in its transaction hash set for future reference.
//
// Note, the method assumes the hashes are correct and correspond to the list of
// transactions being sent.
func (p *peer) SendPooledTransactionsRLP(hashes []common.Hash, txs []rlp.RawValue) error {
	// Mark all the transactions as known, but ensure we don't overflow our limits
	p.knownTxs.Add(hashes...)
	return p2p.Send(p.rw, ctxc.PooledTransactionsMsg, txs)
}

// SendNewBlockHashes announces the availability of a number of blocks through
// a hash notification.
func (p *peer) SendNewBlockHashes(hashes []common.Hash, numbers []uint64) error {
	// Mark all the block hashes as known, but ensure we don't overflow our limits
	p.knownBlocks.Add(hashes...)
	request := make(newBlockHashesData, len(hashes))
	for i := 0; i < len(hashes); i++ {
		request[i].Hash = hashes[i]
		request[i].Number = numbers[i]
	}
	return p2p.Send(p.rw, ctxc.NewBlockHashesMsg, request)
}

// AsyncSendNewBlockHash queues the availability of a block for propagation to a
// remote peer. If the peer's broadcast queue is full, the event is silently
// dropped.
func (p *peer) AsyncSendNewBlockHash(block *types.Block) {
	select {
	case p.queuedBlockAnns <- block:
		// Mark all the block hash as known, but ensure we don't overflow our limits
		p.knownBlocks.Add(block.Hash())
	default:
		p.Log().Debug("Dropping block announcement", "number", block.NumberU64(), "hash", block.Hash())
	}
}

// SendNewBlock propagates an entire block to a remote peer.
func (p *peer) SendNewBlock(block *types.Block, td *big.Int) error {
	// Mark all the block hash as known, but ensure we don't overflow our limits
	p.knownBlocks.Add(block.Hash())
	return p2p.Send(p.rw, ctxc.NewBlockMsg, []interface{}{block, td})
}

// AsyncSendNewBlock queues an entire block for propagation to a remote peer. If
// the peer's broadcast queue is full, the event is silently dropped.
func (p *peer) AsyncSendNewBlock(block *types.Block, td *big.Int) {
	select {
	case p.queuedBlocks <- &propEvent{block: block, td: td}:
		// Mark all the block hash as known, but ensure we don't overflow our limits
		p.knownBlocks.Add(block.Hash())
	default:
		p.Log().Debug("Dropping block propagation", "number", block.NumberU64(), "hash", block.Hash())
	}
}

// SendBlockHeaders sends a batch of block headers to the remote peer.
func (p *peer) SendBlockHeaders(headers []rlp.RawValue) error {
	return p2p.Send(p.rw, ctxc.BlockHeadersMsg, headers)
}

// SendBlockBodies sends a batch of block contents to the remote peer.
func (p *peer) SendBlockBodies(bodies []*blockBody) error {
	return p2p.Send(p.rw, ctxc.BlockBodiesMsg, blockBodiesData(bodies))
}

// SendBlockBodiesRLP sends a batch of block contents to the remote peer from
// an already RLP encoded format.
func (p *peer) SendBlockBodiesRLP(bodies []rlp.RawValue) error {
	return p2p.Send(p.rw, ctxc.BlockBodiesMsg, bodies)
}

// SendNodeDataRLP sends a batch of arbitrary internal data, corresponding to the
// hashes requested.
func (p *peer) SendNodeData(data [][]byte) error {
	return p2p.Send(p.rw, ctxc.NodeDataMsg, data)
}

// SendReceiptsRLP sends a batch of transaction receipts, corresponding to the
// ones requested from an already RLP encoded format.
func (p *peer) SendReceiptsRLP(receipts []rlp.RawValue) error {
	return p2p.Send(p.rw, ctxc.ReceiptsMsg, receipts)
}

// RequestOneHeader is a wrapper around the header query functions to fetch a
// single header. It is used solely by the fetcher.
func (p *peer) RequestOneHeader(hash common.Hash) error {
	p.Log().Debug("Fetching single header", "hash", hash)
	return p2p.Send(p.rw, ctxc.GetBlockHeadersMsg, &getBlockHeadersData{Origin: hashOrNumber{Hash: hash}, Amount: uint64(1), Skip: uint64(0), Reverse: false})
}

// RequestHeadersByHash fetches a batch of blocks' headers corresponding to the
// specified header query, based on the hash of an origin block.
func (p *peer) RequestHeadersByHash(origin common.Hash, amount int, skip int, reverse bool) error {
	p.Log().Debug("Fetching batch of headers", "count", amount, "fromhash", origin, "skip", skip, "reverse", reverse)
	return p2p.Send(p.rw, ctxc.GetBlockHeadersMsg, &getBlockHeadersData{Origin: hashOrNumber{Hash: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
}

// RequestHeadersByNumber fetches a batch of blocks' headers corresponding to the
// specified header query, based on the number of an origin block.
func (p *peer) RequestHeadersByNumber(origin uint64, amount int, skip int, reverse bool) error {
	p.Log().Debug("Fetching batch of headers", "count", amount, "fromnum", origin, "skip", skip, "reverse", reverse)
	return p2p.Send(p.rw, ctxc.GetBlockHeadersMsg, &getBlockHeadersData{Origin: hashOrNumber{Number: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
}

// RequestBodies fetches a batch of blocks' bodies corresponding to the hashes
// specified.
func (p *peer) RequestBodies(hashes []common.Hash) error {
	p.Log().Debug("Fetching batch of block bodies", "count", len(hashes))
	return p2p.Send(p.rw, ctxc.GetBlockBodiesMsg, hashes)
}

// RequestNodeData fetches a batch of arbitrary data from a node's known state
// data, corresponding to the specified hashes.
func (p *peer) RequestNodeData(hashes []common.Hash) error {
	p.Log().Debug("Fetching batch of state data", "count", len(hashes))
	return p2p.Send(p.rw, ctxc.GetNodeDataMsg, hashes)
}

// RequestReceipts fetches a batch of transaction receipts from a remote node.
func (p *peer) RequestReceipts(hashes []common.Hash) error {
	p.Log().Debug("Fetching batch of receipts", "count", len(hashes))
	return p2p.Send(p.rw, ctxc.GetReceiptsMsg, hashes)
}

// RequestTxs fetches a batch of transactions from a remote node.
func (p *peer) RequestTxs(hashes []common.Hash) error {
	p.Log().Debug("Fetching batch of transactions", "count", len(hashes))
	return p2p.Send(p.rw, ctxc.GetPooledTransactionsMsg, hashes)
}

// String implements fmt.Stringer.
func (p *peer) String() string {
	return fmt.Sprintf("Peer %s [%s]", p.id,
		fmt.Sprintf("ctxc/%2d", p.version),
	)
}

// knownCache is a cache for known hashes.
type knownCache struct {
	hashes mapset.Set[common.Hash]
	max    int
}

// newKnownCache creates a new knownCache with a max capacity.
func newKnownCache(max int) *knownCache {
	return &knownCache{
		max:    max,
		hashes: mapset.NewSet[common.Hash](),
	}
}

// Add adds a list of elements to the set.
func (k *knownCache) Add(hashes ...common.Hash) {
	for k.hashes.Cardinality() > max(0, k.max-len(hashes)) {
		k.hashes.Pop()
	}
	for _, hash := range hashes {
		k.hashes.Add(hash)
	}
}

// Contains returns whether the given item is in the set.
func (k *knownCache) Contains(hash common.Hash) bool {
	return k.hashes.Contains(hash)
}

// Cardinality returns the number of elements in the set.
func (k *knownCache) Cardinality() int {
	return k.hashes.Cardinality()
}