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+// Copyright 2015 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 eth
+
+import (
+ "errors"
+ "fmt"
+ "math/big"
+ "sync"
+ "time"
+
+ mapset "github.com/deckarep/golang-set"
+ "github.com/ethereum/go-ethereum/common"
+ "github.com/ethereum/go-ethereum/core/types"
+ "github.com/ethereum/go-ethereum/p2p"
+ "github.com/ethereum/go-ethereum/rlp"
+)
+
+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 transaction lists to queue up before
+ // dropping broadcasts. This is a sensitive number as a transaction list might
+ // contain a single transaction, or thousands.
+ maxQueuedTxs = 128
+
+ // maxQueuedProps 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.
+ maxQueuedProps = 4
+
+ // maxQueuedAnns 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.
+ maxQueuedAnns = 4
+
+ handshakeTimeout = 5 * time.Second
+)
+
+// PeerInfo represents a short summary of the Ethereum sub-protocol metadata known
+// about a connected peer.
+type PeerInfo struct {
+ Version int `json:"version"` // Ethereum 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 int // Protocol version negotiated
+ syncDrop *time.Timer // Timed connection dropper if sync progress isn't validated in time
+
+ head common.Hash
+ td *big.Int
+ lock sync.RWMutex
+
+ knownTxs mapset.Set // Set of transaction hashes known to be known by this peer
+ knownBlocks mapset.Set // Set of block hashes known to be known by this peer
+ queuedTxs chan []*types.Transaction // Queue of transactions to broadcast to the peer
+ queuedProps chan *propEvent // Queue of blocks to broadcast to the peer
+ queuedAnns chan *types.Block // Queue of blocks to announce to the peer
+ term chan struct{} // Termination channel to stop the broadcaster
+}
+
+func newPeer(version int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
+ return &peer{
+ Peer: p,
+ rw: rw,
+ version: version,
+ id: fmt.Sprintf("%x", p.ID().Bytes()[:8]),
+ knownTxs: mapset.NewSet(),
+ knownBlocks: mapset.NewSet(),
+ queuedTxs: make(chan []*types.Transaction, maxQueuedTxs),
+ queuedProps: make(chan *propEvent, maxQueuedProps),
+ queuedAnns: make(chan *types.Block, maxQueuedAnns),
+ term: make(chan struct{}),
+ }
+}
+
+// broadcast is a write loop that multiplexes block propagations, announcements
+// and transaction broadcasts into the remote peer. The goal is to have an async
+// writer that does not lock up node internals.
+func (p *peer) broadcast() {
+ for {
+ select {
+ case txs := <-p.queuedTxs:
+ if err := p.SendTransactions(txs); err != nil {
+ return
+ }
+ p.Log().Trace("Broadcast transactions", "count", len(txs))
+
+ case prop := <-p.queuedProps:
+ if err := p.SendNewBlock(prop.block, prop.td); err != nil {
+ return
+ }
+ p.Log().Trace("Propagated block", "number", prop.block.Number(), "hash", prop.block.Hash(), "td", prop.td)
+
+ case block := <-p.queuedAnns:
+ if err := p.SendNewBlockHashes([]common.Hash{block.Hash()}, []uint64{block.NumberU64()}); err != nil {
+ return
+ }
+ p.Log().Trace("Announced block", "number", block.Number(), "hash", block.Hash())
+
+ case <-p.term:
+ return
+ }
+ }
+}
+
+// close signals the broadcast goroutine to terminate.
+func (p *peer) close() {
+ close(p.term)
+}
+
+// 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)
+}
+
+// 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
+ for p.knownBlocks.Cardinality() >= maxKnownBlocks {
+ p.knownBlocks.Pop()
+ }
+ 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
+ for p.knownTxs.Cardinality() >= maxKnownTxs {
+ p.knownTxs.Pop()
+ }
+ p.knownTxs.Add(hash)
+}
+
+// SendTransactions sends transactions to the peer and includes the hashes
+// in its transaction hash set for future reference.
+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())
+ }
+ for p.knownTxs.Cardinality() >= maxKnownTxs {
+ p.knownTxs.Pop()
+ }
+ return p2p.Send(p.rw, TxMsg, txs)
+}
+
+// AsyncSendTransactions queues list of transactions propagation to a remote
+// peer. If the peer's broadcast queue is full, the event is silently dropped.
+func (p *peer) AsyncSendTransactions(txs []*types.Transaction) {
+ select {
+ case p.queuedTxs <- txs:
+ // Mark all the transactions as known, but ensure we don't overflow our limits
+ for _, tx := range txs {
+ p.knownTxs.Add(tx.Hash())
+ }
+ for p.knownTxs.Cardinality() >= maxKnownTxs {
+ p.knownTxs.Pop()
+ }
+ default:
+ p.Log().Debug("Dropping transaction propagation", "count", len(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
+ for _, hash := range hashes {
+ p.knownBlocks.Add(hash)
+ }
+ for p.knownBlocks.Cardinality() >= maxKnownBlocks {
+ p.knownBlocks.Pop()
+ }
+ 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, 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.queuedAnns <- block:
+ // Mark all the block hash as known, but ensure we don't overflow our limits
+ p.knownBlocks.Add(block.Hash())
+ for p.knownBlocks.Cardinality() >= maxKnownBlocks {
+ p.knownBlocks.Pop()
+ }
+ 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())
+ for p.knownBlocks.Cardinality() >= maxKnownBlocks {
+ p.knownBlocks.Pop()
+ }
+ return p2p.Send(p.rw, 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.queuedProps <- &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())
+ for p.knownBlocks.Cardinality() >= maxKnownBlocks {
+ p.knownBlocks.Pop()
+ }
+ 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 []*types.Header) error {
+ return p2p.Send(p.rw, 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, 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, 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, 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, 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, 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, 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, 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, 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, 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, GetReceiptsMsg, hashes)
+}
+
+// Handshake executes the eth protocol handshake, negotiating version number,
+// network IDs, difficulties, head and genesis blocks.
+func (p *peer) Handshake(network uint64, td *big.Int, head common.Hash, genesis common.Hash) error {
+ // Send out own handshake in a new thread
+ errc := make(chan error, 2)
+ var status statusData // safe to read after two values have been received from errc
+
+ go func() {
+ errc <- p2p.Send(p.rw, StatusMsg, &statusData{
+ ProtocolVersion: uint32(p.version),
+ NetworkId: network,
+ TD: td,
+ CurrentBlock: head,
+ GenesisBlock: genesis,
+ })
+ }()
+ go func() {
+ errc <- p.readStatus(network, &status, genesis)
+ }()
+ timeout := time.NewTimer(handshakeTimeout)
+ defer timeout.Stop()
+ for i := 0; i < 2; i++ {
+ select {
+ case err := <-errc:
+ if err != nil {
+ return err
+ }
+ case <-timeout.C:
+ return p2p.DiscReadTimeout
+ }
+ }
+ p.td, p.head = status.TD, status.CurrentBlock
+ return nil
+}
+
+func (p *peer) readStatus(network uint64, status *statusData, genesis common.Hash) (err error) {
+ msg, err := p.rw.ReadMsg()
+ if err != nil {
+ return err
+ }
+ if msg.Code != StatusMsg {
+ return errResp(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
+ }
+ if msg.Size > protocolMaxMsgSize {
+ return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, protocolMaxMsgSize)
+ }
+ // Decode the handshake and make sure everything matches
+ if err := msg.Decode(&status); err != nil {
+ return errResp(ErrDecode, "msg %v: %v", msg, err)
+ }
+ if status.GenesisBlock != genesis {
+ return errResp(ErrGenesisBlockMismatch, "%x (!= %x)", status.GenesisBlock[:8], genesis[:8])
+ }
+ if status.NetworkId != network {
+ return errResp(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, network)
+ }
+ if int(status.ProtocolVersion) != p.version {
+ return errResp(ErrProtocolVersionMismatch, "%d (!= %d)", status.ProtocolVersion, p.version)
+ }
+ return nil
+}
+
+// String implements fmt.Stringer.
+func (p *peer) String() string {
+ return fmt.Sprintf("Peer %s [%s]", p.id,
+ fmt.Sprintf("eth/%2d", p.version),
+ )
+}
+
+// peerSet represents the collection of active peers currently participating in
+// the Ethereum sub-protocol.
+type peerSet struct {
+ peers map[string]*peer
+ lock sync.RWMutex
+ closed bool
+}
+
+// newPeerSet creates a new peer set to track the active participants.
+func newPeerSet() *peerSet {
+ return &peerSet{
+ peers: make(map[string]*peer),
+ }
+}
+
+// Register injects a new peer into the working set, or returns an error if the
+// peer is already known. If a new peer it registered, its broadcast loop is also
+// started.
+func (ps *peerSet) Register(p *peer) error {
+ ps.lock.Lock()
+ defer ps.lock.Unlock()
+
+ if ps.closed {
+ return errClosed
+ }
+ if _, ok := ps.peers[p.id]; ok {
+ return errAlreadyRegistered
+ }
+ ps.peers[p.id] = p
+ go p.broadcast()
+
+ return nil
+}
+
+// Unregister removes a remote peer from the active set, disabling any further
+// actions to/from that particular entity.
+func (ps *peerSet) Unregister(id string) error {
+ ps.lock.Lock()
+ defer ps.lock.Unlock()
+
+ p, ok := ps.peers[id]
+ if !ok {
+ return errNotRegistered
+ }
+ delete(ps.peers, id)
+ p.close()
+
+ return nil
+}
+
+// Peer retrieves the registered peer with the given id.
+func (ps *peerSet) Peer(id string) *peer {
+ ps.lock.RLock()
+ defer ps.lock.RUnlock()
+
+ return ps.peers[id]
+}
+
+// Len returns if the current number of peers in the set.
+func (ps *peerSet) Len() int {
+ ps.lock.RLock()
+ defer ps.lock.RUnlock()
+
+ return len(ps.peers)
+}
+
+// PeersWithoutBlock retrieves a list of peers that do not have a given block in
+// their set of known hashes.
+func (ps *peerSet) PeersWithoutBlock(hash common.Hash) []*peer {
+ ps.lock.RLock()
+ defer ps.lock.RUnlock()
+
+ list := make([]*peer, 0, len(ps.peers))
+ for _, p := range ps.peers {
+ if !p.knownBlocks.Contains(hash) {
+ list = append(list, p)
+ }
+ }
+ return list
+}
+
+// PeersWithoutTx retrieves a list of peers that do not have a given transaction
+// in their set of known hashes.
+func (ps *peerSet) PeersWithoutTx(hash common.Hash) []*peer {
+ ps.lock.RLock()
+ defer ps.lock.RUnlock()
+
+ list := make([]*peer, 0, len(ps.peers))
+ for _, p := range ps.peers {
+ if !p.knownTxs.Contains(hash) {
+ list = append(list, p)
+ }
+ }
+ return list
+}
+
+// BestPeer retrieves the known peer with the currently highest total difficulty.
+func (ps *peerSet) BestPeer() *peer {
+ ps.lock.RLock()
+ defer ps.lock.RUnlock()
+
+ var (
+ bestPeer *peer
+ bestTd *big.Int
+ )
+ for _, p := range ps.peers {
+ if _, td := p.Head(); bestPeer == nil || td.Cmp(bestTd) > 0 {
+ bestPeer, bestTd = p, td
+ }
+ }
+ return bestPeer
+}
+
+// Close disconnects all peers.
+// No new peers can be registered after Close has returned.
+func (ps *peerSet) Close() {
+ ps.lock.Lock()
+ defer ps.lock.Unlock()
+
+ for _, p := range ps.peers {
+ p.Disconnect(p2p.DiscQuitting)
+ }
+ ps.closed = true
+}
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