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Peer.swift
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Peer.swift
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//
// Peer.swift
//
// Copyright © 2018 Kishikawa Katsumi
// Copyright © 2018 BitcoinCashKit developers
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
import Foundation
private let protocolVersion: Int32 = 70_015
private let bufferSize = 4096
public class Peer: NSObject, StreamDelegate {
public let host: String
public var port: UInt32 {
return network.port
}
public let network: Network
public weak var delegate: PeerDelegate?
let context = Context()
var latestBlockHash: Data
class Context {
var packets = Data()
/// Transactions to be sent
var transactions = [Data: Transaction]()
var pingTime = Date()
var estimatedHeight: Int32 = 0
var sentVersion = false
var sentVerack = false
var gotVerack = false
var sentGetAddr = false
var sentFilterLoad = false
var sentGetData = false
var sentMemPool = false
var sentGetBlocks = false
var isSyncing = false
var inventoryItems = [Data: InventoryItem]()
}
private var readStream: Unmanaged<CFReadStream>?
private var writeStream: Unmanaged<CFWriteStream>?
private var inputStream: InputStream!
private var outputStream: OutputStream!
public convenience init(network: Network = .testnet) {
self.init(host: network.dnsSeeds[Int(arc4random_uniform(UInt32(network.dnsSeeds.count)))], network: network)
}
public init(host: String, network: Network = .testnet) {
self.host = host
self.network = network
latestBlockHash = network.genesisBlock
}
deinit {
disconnect()
}
public func connect() {
log("connecting")
CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host as CFString, port, &readStream, &writeStream)
inputStream = readStream!.takeRetainedValue()
outputStream = writeStream!.takeRetainedValue()
inputStream.delegate = self
outputStream.delegate = self
inputStream.schedule(in: .current, forMode: .commonModes)
outputStream.schedule(in: .current, forMode: .commonModes)
inputStream.open()
outputStream.open()
}
public func disconnect() {
guard readStream != nil && readStream != nil else {
return
}
inputStream.delegate = nil
outputStream.delegate = nil
inputStream.remove(from: .current, forMode: .commonModes)
outputStream.remove(from: .current, forMode: .commonModes)
inputStream.close()
outputStream.close()
readStream = nil
writeStream = nil
log("disconnected")
self.delegate?.peerDidDisconnect(self)
}
public func startSync(filters: [Data] = [], latestBlockHash: Data) {
self.latestBlockHash = latestBlockHash
context.isSyncing = true
if !self.context.sentFilterLoad {
sendFilterLoadMessage(filters: filters)
self.context.sentFilterLoad = true
if !self.context.sentMemPool {
self.sendMemoryPoolMessage()
self.context.sentMemPool = true
}
}
self.sendGetBlocksMessage()
}
public func sendTransaction(transaction: Transaction) {
sendTransactionInventory(transaction: transaction)
}
// swiftlint:disable:next cyclomatic_complexity
public func stream(_ stream: Stream, handle eventCode: Stream.Event) {
switch stream {
case let stream as InputStream:
switch eventCode {
case .openCompleted:
log("socket connected")
case .hasBytesAvailable:
readAvailableBytes(stream: stream)
case .hasSpaceAvailable:
break
case .errorOccurred:
log("socket error occurred")
disconnect()
case .endEncountered:
log("socket closed")
disconnect()
default:
break
}
case _ as OutputStream:
switch eventCode {
case .openCompleted:
break
case .hasBytesAvailable:
break
case .hasSpaceAvailable:
if !context.sentVersion {
sendVersionMessage()
context.sentVersion = true
}
case .errorOccurred:
log("socket error occurred")
disconnect()
case .endEncountered:
log("socket closed")
disconnect()
default:
break
}
default:
break
}
}
// swiftlint:disable:next cyclomatic_complexity
private func readAvailableBytes(stream: InputStream) {
let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)
defer { buffer.deallocate() }
while stream.hasBytesAvailable {
let numberOfBytesRead = stream.read(buffer, maxLength: bufferSize)
if numberOfBytesRead <= 0 {
if stream.streamError != nil { break }
} else {
context.packets += Data(bytesNoCopy: buffer, count: numberOfBytesRead, deallocator: .none)
}
}
while context.packets.count >= Message.minimumLength {
guard let message = Message.deserialize(context.packets) else {
return
}
autoreleasepool {
context.packets = Data(context.packets.dropFirst(Message.minimumLength + Int(message.length)))
switch message.command {
case "version":
// When a node creates an outgoing connection, it will immediately advertise its version.
// The remote node will respond with its version. No further communication is possible until both peers have exchanged their version.
handleVersionMessage(payload: message.payload)
case "verack":
// The verack message is sent in reply to version. This message consists of only a message header with the command string "verack".
handleVerackMessage(payload: message.payload)
case "addr":
// Provide information on known nodes of the network. Non-advertised nodes should be forgotten after typically 3 hours
handleAddressMessage(payload: message.payload)
case "inv":
// Allows a node to advertise its knowledge of one or more objects. It can be received unsolicited, or in reply to getblocks.
// Payload (maximum 50,000 entries, which is just over 1.8 megabytes):
handleInventoryMessage(payload: message.payload)
case "getdata":
// getdata is used in response to inv, to retrieve the content of a specific object, and is usually sent after receiving an inv packet, after filtering known elements.
// It can be used to retrieve transactions, but only if they are in the memory pool or relay set - arbitrary access to transactions in the chain is not allowed to avoid having clients start to depend on nodes having full transaction indexes (which modern nodes do not).
// Payload (maximum 50,000 entries, which is just over 1.8 megabytes):
handleGetDataMessage(payload: message.payload)
case "notfound":
// notfound is a response to a getdata, sent if any requested data items could not be relayed, for example, because the requested transaction was not in the memory pool or relay set.
break
case "block":
// The block message is sent in response to a getdata message which requests transaction information from a block hash.
handleBlockMessage(payload: message.payload)
case "tx":
// tx describes a bitcoin transaction, in reply to getdata
handleTransaction(payload: message.payload)
case "ping":
// The ping message is sent primarily to confirm that the TCP/IP connection is still valid. An error in transmission is presumed to be a closed connection and the address is removed as a current peer.
handlePingMessage(payload: message.payload)
case "merkleblock":
handleMerkleBlockMessage(payload: message.payload)
case "reject":
// The reject message is sent when messages are rejected.
handleRejectMessage(payload: message.payload)
default:
break
}
}
}
}
private func sendMessage(_ message: Message) {
log("sending \(message.command)")
let data = message.serialized()
_ = data.withUnsafeBytes { outputStream.write($0, maxLength: data.count) }
}
private func sendVersionMessage() {
let version = VersionMessage(version: protocolVersion,
services: 0x00,
timestamp: Int64(Date().timeIntervalSince1970),
yourAddress: NetworkAddress(services: 0x00,
address: "::ffff:127.0.0.1",
port: UInt16(port)),
myAddress: NetworkAddress(services: 0x00,
address: "::ffff:127.0.0.1",
port: UInt16(port)),
nonce: 0,
userAgent: "/BitcoinCashKit:0.2.1/",
startHeight: -1,
relay: false)
let payload = version.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "version", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func sendVerackMessage() {
let payload = Data()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "verack", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
context.pingTime = Date()
}
private func sendFilterLoadMessage(filters: [Data]) {
guard !filters.isEmpty else { return }
let nTweak = arc4random_uniform(UInt32.max)
var filter = BloomFilter(elements: filters.count, falsePositiveRate: 0.000_05, randomNonce: nTweak)
for f in filters {
filter.insert(f)
}
let filterData = Data(filter.data)
let filterLoad = FilterLoadMessage(filter: filterData, nHashFuncs: filter.nHashFuncs, nTweak: nTweak, nFlags: 0)
let payload = filterLoad.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "filterload", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func sendMemoryPoolMessage() {
let payload = Data()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "mempool", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func sendGetBlocksMessage() {
let blockLocatorHash = latestBlockHash
let getBlocks = GetBlocksMessage(version: UInt32(protocolVersion), hashCount: 1, blockLocatorHashes: blockLocatorHash, hashStop: Data(count: 32))
let payload = getBlocks.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "getblocks", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func sendGetDataMessage(message: InventoryMessage) {
let payload = message.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "getdata", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func sendTransactionInventory(transaction: Transaction) {
let txId = Crypto.sha256sha256(transaction.serialized())
context.transactions[txId] = transaction
let inv = InventoryMessage(count: 1, inventoryItems: [InventoryItem(type: InventoryItem.ObjectType.transactionMessage.rawValue, hash: txId)])
let payload = inv.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "inv", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func handleVersionMessage(payload: Data) {
let version = VersionMessage.deserialize(payload)
context.estimatedHeight = version.startHeight ?? 0
log("got version \(version.version), useragent: \(version.userAgent?.value ?? ""), services: \(ServiceFlags(rawValue: version.services))")
delegate?.peer(self, didReceiveVersionMessage: version)
if !context.sentVerack {
sendVerackMessage()
context.sentVerack = true
}
}
private func handleVerackMessage(payload: Data) {
log("got verack in \(String(format: "%g", Date().timeIntervalSince(context.pingTime)))s")
context.gotVerack = true
delegate?.peerDidConnect(self)
}
private func handleAddressMessage(payload: Data) {
let address = AddressMessage.deserialize(payload)
log("got addr with \(address.count) address(es)")
delegate?.peer(self, didReceiveAddressMessage: address)
}
private func handleGetDataMessage(payload: Data) {
let getData = GetDataMessage.deserialize(payload)
log("got getdata with \(getData.count) item(s)")
delegate?.peer(self, didReceiveGetDataMessage: getData)
for item in getData.inventoryItems {
switch item.objectType {
case .error:
break
case .transactionMessage:
// Send transaction
if let transaction = context.transactions[item.hash] {
let payload = transaction.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "tx", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
case .blockMessage:
break
case .filteredBlockMessage:
break
case .compactBlockMessage:
break
case .unknown:
break
}
}
}
private func handleInventoryMessage(payload: Data) {
let inventory = InventoryMessage.deserialize(payload)
log("got inv with \(inventory.count) item(s)")
delegate?.peer(self, didReceiveInventoryMessage: inventory)
// 1. filteredBlockMessageとtransactionsは受け取る
let transactionItems: [InventoryItem] = inventory.inventoryItems.filter { $0.objectType == .transactionMessage }
let blockItems: [InventoryItem] = inventory.inventoryItems
.filter { $0.objectType == .blockMessage || $0.objectType == .filteredBlockMessage }
.map { InventoryItem(type: InventoryItem.ObjectType.filteredBlockMessage.rawValue, hash: $0.hash) }
let filterdItems: [InventoryItem] = transactionItems + blockItems
guard !filterdItems.isEmpty else {
return
}
sendGetDataMessage(message: InventoryMessage(count: VarInt(filterdItems.count), inventoryItems: filterdItems))
for item in filterdItems {
context.inventoryItems[Data(item.hash.reversed())] = item
}
}
private func handleBlockMessage(payload: Data) {
let block = BlockMessage.deserialize(payload)
let blockHash = Data(Crypto.sha256sha256(payload.prefix(80)).reversed())
delegate?.peer(self, didReceiveBlockMessage: block, hash: blockHash)
context.inventoryItems[blockHash] = nil
if context.inventoryItems.isEmpty {
latestBlockHash = blockHash
sendGetBlocksMessage()
}
}
private func handleMerkleBlockMessage(payload: Data) {
let merkleBlock = MerkleBlockMessage.deserialize(payload)
let blockHash = Crypto.sha256sha256(payload.prefix(80))
delegate?.peer(self, didReceiveMerkleBlockMessage: merkleBlock, hash: blockHash)
context.inventoryItems[Data(blockHash.reversed())] = nil
if context.inventoryItems.isEmpty {
latestBlockHash = blockHash
sendGetBlocksMessage()
}
}
private func handleTransaction(payload: Data) {
let transaction = Transaction.deserialize(payload)
let txHash = Data(Crypto.sha256sha256(payload).reversed())
log("got tx: \(txHash.hex)")
delegate?.peer(self, didReceiveTransaction: transaction, hash: txHash)
}
private func handlePingMessage(payload: Data) {
let ping = PingMessage.deserialize(payload)
let pong = PongMessage(nonce: ping.nonce)
log("got ping")
let payload = pong.serialized()
let checksum = Data(Crypto.sha256sha256(payload).prefix(4))
let message = Message(magic: network.magic, command: "pong", length: UInt32(payload.count), checksum: checksum, payload: payload)
sendMessage(message)
}
private func handleRejectMessage(payload: Data) {
let reject = RejectMessage.deserialize(payload)
log("rejected \(reject.message) code: 0x\(String(reject.ccode, radix: 16)) reason: \(reject.reason), data: \(reject.data.hex)")
delegate?.peer(self, didReceiveRejectMessage: reject)
}
private func log(_ message: String) {
print("\(host):\(port) \(message)")
}
}
public protocol PeerDelegate: class {
func peerDidConnect(_ peer: Peer)
func peerDidDisconnect(_ peer: Peer)
func peer(_ peer: Peer, didReceiveVersionMessage message: VersionMessage)
func peer(_ peer: Peer, didReceiveAddressMessage message: AddressMessage)
func peer(_ peer: Peer, didReceiveGetDataMessage message: GetDataMessage)
func peer(_ peer: Peer, didReceiveInventoryMessage message: InventoryMessage)
func peer(_ peer: Peer, didReceiveBlockMessage message: BlockMessage, hash: Data)
func peer(_ peer: Peer, didReceiveMerkleBlockMessage message: MerkleBlockMessage, hash: Data)
func peer(_ peer: Peer, didReceiveTransaction transaction: Transaction, hash: Data)
func peer(_ peer: Peer, didReceiveRejectMessage message: RejectMessage)
}
extension PeerDelegate {
public func peerDidConnect(_ peer: Peer) {}
public func peerDidDisconnect(_ peer: Peer) {}
public func peer(_ peer: Peer, didReceiveVersionMessage message: VersionMessage) {}
public func peer(_ peer: Peer, didReceiveAddressMessage message: AddressMessage) {}
public func peer(_ peer: Peer, didReceiveGetDataMessage message: GetDataMessage) {}
public func peer(_ peer: Peer, didReceiveInventoryMessage message: InventoryMessage) {}
public func peer(_ peer: Peer, didReceiveBlockMessage message: BlockMessage, hash: Data) {}
public func peer(_ peer: Peer, didReceiveMerkleBlockMessage message: MerkleBlockMessage, hash: Data) {}
public func peer(_ peer: Peer, didReceiveTransaction transaction: Transaction, hash: Data) {}
public func peer(_ peer: Peer, didReceiveRejectMessage message: RejectMessage) {}
}