_ Git - dnsseed-rust/blob - src/datastore.rs

   1 use std::{cmp, mem};
   2 use std::collections::{HashSet, HashMap, hash_map};
   3 use std::sync::{Arc, RwLock};
   4 use std::net::SocketAddr;
   5 use std::time::{Duration, Instant};
   6 use std::io::{BufRead, BufReader};
   7
   8 use bitcoin::network::address::Address;
   9
  10 use rand::thread_rng;
  11 use rand::seq::{SliceRandom, IteratorRandom};
  12
  13 use tokio::prelude::*;
  14 use tokio::fs::File;
  15 use tokio::io::write_all;
  16
  17 use regex::Regex;
  18
  19 #[derive(Clone, Copy, Hash, PartialEq, Eq)]
  20 pub enum AddressState {
  21         Untested,
  22         LowBlockCount,
  23         HighBlockCount,
  24         LowVersion,
  25         BadVersion,
  26         NotFullNode,
  27         ProtocolViolation,
  28         Timeout,
  29         TimeoutDuringRequest,
  30         TimeoutAwaitingPong,
  31         TimeoutAwaitingAddr,
  32         TimeoutAwaitingBlock,
  33         Good,
  34         WasGood,
  35 }
  36
  37 impl AddressState {
  38         pub fn from_num(num: u8) -> Option<AddressState> {
  39                 match num {
  40                         0x0 => Some(AddressState::Untested),
  41                         0x1 => Some(AddressState::LowBlockCount),
  42                         0x2 => Some(AddressState::HighBlockCount),
  43                         0x3 => Some(AddressState::LowVersion),
  44                         0x4 => Some(AddressState::BadVersion),
  45                         0x5 => Some(AddressState::NotFullNode),
  46                         0x6 => Some(AddressState::ProtocolViolation),
  47                         0x7 => Some(AddressState::Timeout),
  48                         0x8 => Some(AddressState::TimeoutDuringRequest),
  49                         0x9 => Some(AddressState::TimeoutAwaitingPong),
  50                         0xa => Some(AddressState::TimeoutAwaitingAddr),
  51                         0xb => Some(AddressState::TimeoutAwaitingBlock),
  52                         0xc => Some(AddressState::Good),
  53                         0xd => Some(AddressState::WasGood),
  54                         _   => None,
  55                 }
  56         }
  57
  58         pub fn to_num(&self) -> u8 {
  59                 match *self {
  60                         AddressState::Untested => 0,
  61                         AddressState::LowBlockCount => 1,
  62                         AddressState::HighBlockCount => 2,
  63                         AddressState::LowVersion => 3,
  64                         AddressState::BadVersion => 4,
  65                         AddressState::NotFullNode => 5,
  66                         AddressState::ProtocolViolation => 6,
  67                         AddressState::Timeout => 7,
  68                         AddressState::TimeoutDuringRequest => 8,
  69                         AddressState::TimeoutAwaitingPong => 9,
  70                         AddressState::TimeoutAwaitingAddr => 10,
  71                         AddressState::TimeoutAwaitingBlock => 11,
  72                         AddressState::Good => 12,
  73                         AddressState::WasGood => 13,
  74                 }
  75         }
  76
  77         pub fn to_str(&self) -> &'static str {
  78                 match *self {
  79                         AddressState::Untested => "Untested",
  80                         AddressState::LowBlockCount => "Low Block Count",
  81                         AddressState::HighBlockCount => "High Block Count",
  82                         AddressState::LowVersion => "Low Version",
  83                         AddressState::BadVersion => "Bad Version",
  84                         AddressState::NotFullNode => "Not Full Node",
  85                         AddressState::ProtocolViolation => "Protocol Violation",
  86                         AddressState::Timeout => "Timeout",
  87                         AddressState::TimeoutDuringRequest => "Timeout During Request",
  88                         AddressState::TimeoutAwaitingPong => "Timeout Awaiting Pong",
  89                         AddressState::TimeoutAwaitingAddr => "Timeout Awaiting Addr",
  90                         AddressState::TimeoutAwaitingBlock => "Timeout Awaiting Block",
  91                         AddressState::Good => "Good",
  92                         AddressState::WasGood => "Was Good",
  93                 }
  94         }
  95
  96         pub const fn get_count() -> u8 {
  97                 14
  98         }
  99 }
 100
 101 #[derive(Hash, PartialEq, Eq)]
 102 pub enum U64Setting {
 103         ConnsPerSec,
 104         RunTimeout,
 105         WasGoodTimeout,
 106         RescanInterval(AddressState),
 107         MinProtocolVersion,
 108 }
 109
 110 #[derive(Hash, PartialEq, Eq)]
 111 pub enum RegexSetting {
 112         SubverRegex,
 113 }
 114
 115 struct Node {
 116         last_update: Instant,
 117         last_good: Instant, // Ignored unless state is Good or WasGood
 118         last_services: u64,
 119         state: AddressState,
 120 }
 121
 122 struct Nodes {
 123         good_node_services: Vec<HashSet<SocketAddr>>,
 124         nodes_to_state: HashMap<SocketAddr, Node>,
 125         state_next_scan: Vec<Vec<(Instant, SocketAddr)>>,
 126 }
 127 struct NodesMutRef<'a> {
 128         good_node_services: &'a mut Vec<HashSet<SocketAddr>>,
 129         nodes_to_state: &'a mut HashMap<SocketAddr, Node>,
 130         state_next_scan: &'a mut Vec<Vec<(Instant, SocketAddr)>>,
 131
 132 }
 133 impl Nodes {
 134         fn borrow_mut<'a>(&'a mut self) -> NodesMutRef<'a> {
 135                 NodesMutRef {
 136                         good_node_services: &mut self.good_node_services,
 137                         nodes_to_state: &mut self.nodes_to_state,
 138                         state_next_scan: &mut self.state_next_scan,
 139                 }
 140         }
 141 }
 142
 143 pub struct Store {
 144         u64_settings: RwLock<HashMap<U64Setting, u64>>,
 145         subver_regex: RwLock<Arc<Regex>>,
 146         nodes: RwLock<Nodes>,
 147         store: String,
 148 }
 149
 150 impl Store {
 151         pub fn new(store: String) -> impl Future<Item=Store, Error=()> {
 152                 let settings_future = File::open(store.clone() + "/settings").and_then(|f| {
 153                         let mut l = BufReader::new(f).lines();
 154                         macro_rules! try_read {
 155                                 ($lines: expr, $ty: ty) => { {
 156                                         match $lines.next() {
 157                                                 Some(line) => match line {
 158                                                         Ok(line) => match line.parse::<$ty>() {
 159                                                                 Ok(res) => res,
 160                                                                 Err(e) => return future::err(std::io::Error::new(std::io::ErrorKind::InvalidData, e)),
 161                                                         },
 162                                                         Err(e) => return future::err(e),
 163                                                 },
 164                                                 None => return future::err(std::io::Error::new(std::io::ErrorKind::UnexpectedEof, "")),
 165                                         }
 166                                 } }
 167                         }
 168                         let mut u64s = HashMap::with_capacity(AddressState::get_count() as usize + 4);
 169                         u64s.insert(U64Setting::ConnsPerSec, try_read!(l, u64));
 170                         u64s.insert(U64Setting::RunTimeout, try_read!(l, u64));
 171                         u64s.insert(U64Setting::WasGoodTimeout, try_read!(l, u64));
 172                         u64s.insert(U64Setting::MinProtocolVersion, try_read!(l, u64));
 173                         u64s.insert(U64Setting::RescanInterval(AddressState::Untested), try_read!(l, u64));
 174                         u64s.insert(U64Setting::RescanInterval(AddressState::LowBlockCount), try_read!(l, u64));
 175                         u64s.insert(U64Setting::RescanInterval(AddressState::HighBlockCount), try_read!(l, u64));
 176                         u64s.insert(U64Setting::RescanInterval(AddressState::LowVersion), try_read!(l, u64));
 177                         u64s.insert(U64Setting::RescanInterval(AddressState::BadVersion), try_read!(l, u64));
 178                         u64s.insert(U64Setting::RescanInterval(AddressState::NotFullNode), try_read!(l, u64));
 179                         u64s.insert(U64Setting::RescanInterval(AddressState::ProtocolViolation), try_read!(l, u64));
 180                         u64s.insert(U64Setting::RescanInterval(AddressState::Timeout), try_read!(l, u64));
 181                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutDuringRequest), try_read!(l, u64));
 182                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutAwaitingPong), try_read!(l, u64));
 183                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutAwaitingAddr), try_read!(l, u64));
 184                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutAwaitingBlock), try_read!(l, u64));
 185                         u64s.insert(U64Setting::RescanInterval(AddressState::Good), try_read!(l, u64));
 186                         u64s.insert(U64Setting::RescanInterval(AddressState::WasGood), try_read!(l, u64));
 187                         future::ok((u64s, try_read!(l, Regex)))
 188                 }).or_else(|_| -> future::FutureResult<(HashMap<U64Setting, u64>, Regex), ()> {
 189                         let mut u64s = HashMap::with_capacity(15);
 190                         u64s.insert(U64Setting::ConnsPerSec, 10);
 191                         u64s.insert(U64Setting::RunTimeout, 120);
 192                         u64s.insert(U64Setting::WasGoodTimeout, 21600);
 193                         u64s.insert(U64Setting::RescanInterval(AddressState::Untested), 0);
 194                         u64s.insert(U64Setting::RescanInterval(AddressState::LowBlockCount), 3600);
 195                         u64s.insert(U64Setting::RescanInterval(AddressState::HighBlockCount), 7200);
 196                         u64s.insert(U64Setting::RescanInterval(AddressState::LowVersion), 21600);
 197                         u64s.insert(U64Setting::RescanInterval(AddressState::BadVersion), 21600);
 198                         u64s.insert(U64Setting::RescanInterval(AddressState::NotFullNode), 86400);
 199                         u64s.insert(U64Setting::RescanInterval(AddressState::ProtocolViolation), 86400);
 200                         u64s.insert(U64Setting::RescanInterval(AddressState::Timeout), 86400);
 201                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutDuringRequest), 21600);
 202                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutAwaitingPong), 3600);
 203                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutAwaitingAddr), 1800);
 204                         u64s.insert(U64Setting::RescanInterval(AddressState::TimeoutAwaitingBlock), 3600);
 205                         u64s.insert(U64Setting::RescanInterval(AddressState::Good), 1800);
 206                         u64s.insert(U64Setting::RescanInterval(AddressState::WasGood), 1800);
 207                         u64s.insert(U64Setting::MinProtocolVersion, 70002);
 208                         future::ok((u64s, Regex::new(".*").unwrap()))
 209                 });
 210
 211                 macro_rules! nodes_uninitd {
 212                         () => { {
 213                                 let mut state_vecs = Vec::with_capacity(AddressState::get_count() as usize);
 214                                 for _ in 0..AddressState::get_count() {
 215                                         state_vecs.push(Vec::new());
 216                                 }
 217                                 let mut good_node_services = Vec::with_capacity(64);
 218                                 for _ in 0..64 {
 219                                         good_node_services.push(HashSet::new());
 220                                 }
 221                                 Nodes {
 222                                         good_node_services,
 223                                         nodes_to_state: HashMap::new(),
 224                                         state_next_scan: state_vecs,
 225                                 }
 226                         } }
 227                 }
 228
 229                 let nodes_future = File::open(store.clone() + "/nodes").and_then(|f| {
 230                         let mut res = nodes_uninitd!();
 231                         let l = BufReader::new(f).lines();
 232                         for line_res in l {
 233                                 let line = match line_res {
 234                                         Ok(l) => l,
 235                                         Err(_) => return future::ok(res),
 236                                 };
 237                                 let mut line_iter = line.split(',');
 238                                 macro_rules! try_read {
 239                                         ($lines: expr, $ty: ty) => { {
 240                                                 match $lines.next() {
 241                                                         Some(line) => match line.parse::<$ty>() {
 242                                                                 Ok(res) => res,
 243                                                                 Err(_) => return future::ok(res),
 244                                                         },
 245                                                         None => return future::ok(res),
 246                                                 }
 247                                         } }
 248                                 }
 249                                 let sockaddr = try_read!(line_iter, SocketAddr);
 250                                 let state = try_read!(line_iter, u8);
 251                                 let last_services = try_read!(line_iter, u64);
 252                                 let node = Node {
 253                                         state: match AddressState::from_num(state) {
 254                                                 Some(v) => v,
 255                                                 None => return future::ok(res),
 256                                         },
 257                                         last_services,
 258                                         last_update: Instant::now(),
 259                                         last_good: Instant::now(),
 260                                 };
 261                                 if node.state == AddressState::Good {
 262                                         for i in 0..64 {
 263                                                 if node.last_services & (1 << i) != 0 {
 264                                                         res.good_node_services[i].insert(sockaddr);
 265                                                 }
 266                                         }
 267                                 }
 268                                 res.state_next_scan[node.state.to_num() as usize].push((Instant::now(), sockaddr));
 269                                 res.nodes_to_state.insert(sockaddr, node);
 270                         }
 271                         future::ok(res)
 272                 }).or_else(|_| -> future::FutureResult<Nodes, ()> {
 273                         future::ok(nodes_uninitd!())
 274                 });
 275                 settings_future.join(nodes_future).and_then(move |((u64_settings, regex), nodes)| {
 276                         future::ok(Store {
 277                                 u64_settings: RwLock::new(u64_settings),
 278                                 subver_regex: RwLock::new(Arc::new(regex)),
 279                                 nodes: RwLock::new(nodes),
 280                                 store,
 281                         })
 282                 })
 283         }
 284
 285         pub fn get_u64(&self, setting: U64Setting) -> u64 {
 286                 *self.u64_settings.read().unwrap().get(&setting).unwrap()
 287         }
 288
 289         pub fn set_u64(&self, setting: U64Setting, value: u64) {
 290                 *self.u64_settings.write().unwrap().get_mut(&setting).unwrap() = value;
 291         }
 292
 293         pub fn get_node_count(&self, state: AddressState) -> usize {
 294                 self.nodes.read().unwrap().state_next_scan[state.to_num() as usize].len()
 295         }
 296
 297         pub fn get_regex(&self, _setting: RegexSetting) -> Arc<Regex> {
 298                 Arc::clone(&*self.subver_regex.read().unwrap())
 299         }
 300
 301         pub fn set_regex(&self, _setting: RegexSetting, value: Regex) {
 302                 *self.subver_regex.write().unwrap() = Arc::new(value);
 303         }
 304
 305         pub fn add_fresh_addrs<I: Iterator<Item=SocketAddr>>(&self, addresses: I) -> u64 {
 306                 let mut res = 0;
 307                 let mut nodes = self.nodes.write().unwrap();
 308                 let cur_time = Instant::now();
 309                 for addr in addresses {
 310                         match nodes.nodes_to_state.entry(addr.clone()) {
 311                                 hash_map::Entry::Vacant(e) => {
 312                                         e.insert(Node {
 313                                                 state: AddressState::Untested,
 314                                                 last_services: 0,
 315                                                 last_update: cur_time,
 316                                                 last_good: cur_time,
 317                                         });
 318                                         nodes.state_next_scan[AddressState::Untested.to_num() as usize].push((cur_time, addr));
 319                                         res += 1;
 320                                 },
 321                                 hash_map::Entry::Occupied(_) => {},
 322                         }
 323                 }
 324                 res
 325         }
 326
 327         pub fn add_fresh_nodes(&self, addresses: &Vec<(u32, Address)>) {
 328                 self.add_fresh_addrs(addresses.iter().filter_map(|(_, addr)| {
 329                         match addr.socket_addr() {
 330                                 Ok(socketaddr) => Some(socketaddr),
 331                                 Err(_) => None, // TODO: Handle onions
 332                         }
 333                 }));
 334         }
 335
 336         pub fn set_node_state(&self, addr: SocketAddr, state: AddressState, services: u64) -> AddressState {
 337                 let mut nodes_lock = self.nodes.write().unwrap();
 338                 let nodes = nodes_lock.borrow_mut();
 339                 let now = Instant::now();
 340
 341                 let state_ref = nodes.nodes_to_state.entry(addr).or_insert(Node {
 342                         state: AddressState::Untested,
 343                         last_services: 0,
 344                         last_update: now,
 345                         last_good: now,
 346                 });
 347                 let ret = state_ref.state;
 348                 if (state_ref.state == AddressState::Good || state_ref.state == AddressState::WasGood)
 349                                 && state != AddressState::Good
 350                                 && state_ref.last_good >= now - Duration::from_secs(self.get_u64(U64Setting::WasGoodTimeout)) {
 351                         state_ref.state = AddressState::WasGood;
 352                         for i in 0..64 {
 353                                 if state_ref.last_services & (1 << i) != 0 {
 354                                         nodes.good_node_services[i].remove(&addr);
 355                                 }
 356                         }
 357                         state_ref.last_services = 0;
 358                         nodes.state_next_scan[AddressState::WasGood.to_num() as usize].push((now, addr));
 359                 } else {
 360                         state_ref.state = state;
 361                         if state == AddressState::Good {
 362                                 for i in 0..64 {
 363                                         if services & (1 << i) != 0 && state_ref.last_services & (1 << i) == 0 {
 364                                                 nodes.good_node_services[i].insert(addr);
 365                                         } else if services & (1 << i) == 0 && state_ref.last_services & (1 << i) != 0 {
 366                                                 nodes.good_node_services[i].remove(&addr);
 367                                         }
 368                                 }
 369                                 state_ref.last_services = services;
 370                                 state_ref.last_good = now;
 371                         }
 372                         nodes.state_next_scan[state.to_num() as usize].push((now, addr));
 373                 }
 374                 state_ref.last_update = now;
 375                 ret
 376         }
 377
 378         pub fn save_data(&'static self) -> impl Future<Item=(), Error=()> {
 379                 let settings_file = self.store.clone() + "/settings";
 380                 let settings_future = File::create(settings_file.clone() + ".tmp").and_then(move |f| {
 381                         let settings_string = format!("{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}",
 382                                 self.get_u64(U64Setting::ConnsPerSec),
 383                                 self.get_u64(U64Setting::RunTimeout),
 384                                 self.get_u64(U64Setting::WasGoodTimeout),
 385                                 self.get_u64(U64Setting::MinProtocolVersion),
 386                                 self.get_u64(U64Setting::RescanInterval(AddressState::Untested)),
 387                                 self.get_u64(U64Setting::RescanInterval(AddressState::LowBlockCount)),
 388                                 self.get_u64(U64Setting::RescanInterval(AddressState::HighBlockCount)),
 389                                 self.get_u64(U64Setting::RescanInterval(AddressState::LowVersion)),
 390                                 self.get_u64(U64Setting::RescanInterval(AddressState::BadVersion)),
 391                                 self.get_u64(U64Setting::RescanInterval(AddressState::NotFullNode)),
 392                                 self.get_u64(U64Setting::RescanInterval(AddressState::ProtocolViolation)),
 393                                 self.get_u64(U64Setting::RescanInterval(AddressState::Timeout)),
 394                                 self.get_u64(U64Setting::RescanInterval(AddressState::TimeoutDuringRequest)),
 395                                 self.get_u64(U64Setting::RescanInterval(AddressState::TimeoutAwaitingPong)),
 396                                 self.get_u64(U64Setting::RescanInterval(AddressState::TimeoutAwaitingAddr)),
 397                                 self.get_u64(U64Setting::RescanInterval(AddressState::TimeoutAwaitingBlock)),
 398                                 self.get_u64(U64Setting::RescanInterval(AddressState::Good)),
 399                                 self.get_u64(U64Setting::RescanInterval(AddressState::WasGood)),
 400                                 self.get_regex(RegexSetting::SubverRegex).as_str());
 401                         write_all(f, settings_string).and_then(|(mut f, _)| {
 402                                 f.poll_sync_all()
 403                         }).and_then(|_| {
 404                                 tokio::fs::rename(settings_file.clone() + ".tmp", settings_file)
 405                         })
 406                 });
 407
 408                 let nodes_file = self.store.clone() + "/nodes";
 409                 let nodes_future = File::create(nodes_file.clone() + ".tmp").and_then(move |f| {
 410                         let mut nodes_buff = String::new();
 411                         {
 412                                 let nodes = self.nodes.read().unwrap();
 413                                 nodes_buff.reserve(nodes.nodes_to_state.len() * 20);
 414                                 for (ref sockaddr, ref node) in nodes.nodes_to_state.iter() {
 415                                         nodes_buff += &sockaddr.to_string();
 416                                         nodes_buff += ",";
 417                                         nodes_buff += &node.state.to_num().to_string();
 418                                         nodes_buff += ",";
 419                                         nodes_buff += &node.last_services.to_string();
 420                                         nodes_buff += "\n";
 421                                 }
 422                         }
 423                         write_all(f, nodes_buff)
 424                 }).and_then(|(mut f, _)| {
 425                         f.poll_sync_all()
 426                 }).and_then(|_| {
 427                         tokio::fs::rename(nodes_file.clone() + ".tmp", nodes_file)
 428                 });
 429
 430                 let dns_file = self.store.clone() + "/nodes.dump";
 431                 let dns_future = File::create(dns_file.clone() + ".tmp").and_then(move |f| {
 432                         let mut dns_buff = String::new();
 433                         {
 434                                 let nodes = self.nodes.read().unwrap();
 435                                 let mut rng = thread_rng();
 436                                 for i in &[1u64, 4, 5, 8, 9, 12, 13, 1024, 1025, 1028, 1029, 1032, 1033, 1036, 1037] {
 437                                         let mut v6_set = Vec::new();
 438                                         let mut v4_set = Vec::new();
 439                                         if i.count_ones() == 1 {
 440                                                 for j in 0..64 {
 441                                                         if i & (1 << j) != 0 {
 442                                                                 let set_ref = &nodes.good_node_services[j];
 443                                                                 v4_set = set_ref.iter().filter(|e| e.is_ipv4() && e.port() == 8333)
 444                                                                         .choose_multiple(&mut rng, 21).iter().map(|e| e.ip()).collect();
 445                                                                 v6_set = set_ref.iter().filter(|e| e.is_ipv6() && e.port() == 8333)
 446                                                                         .choose_multiple(&mut rng, 12).iter().map(|e| e.ip()).collect();
 447                                                                 break;
 448                                                         }
 449                                                 }
 450                                         } else if i.count_ones() == 2 {
 451                                                 let mut first_set = None;
 452                                                 let mut second_set = None;
 453                                                 for j in 0..64 {
 454                                                         if i & (1 << j) != 0 {
 455                                                                 if first_set == None {
 456                                                                         first_set = Some(&nodes.good_node_services[j]);
 457                                                                 } else {
 458                                                                         second_set = Some(&nodes.good_node_services[j]);
 459                                                                         break;
 460                                                                 }
 461                                                         }
 462                                                 }
 463                                                 v4_set = first_set.unwrap().intersection(&second_set.unwrap())
 464                                                         .filter(|e| e.is_ipv4() && e.port() == 8333)
 465                                                         .choose_multiple(&mut rng, 21).iter().map(|e| e.ip()).collect();
 466                                                 v6_set = first_set.unwrap().intersection(&second_set.unwrap())
 467                                                         .filter(|e| e.is_ipv6() && e.port() == 8333)
 468                                                         .choose_multiple(&mut rng, 12).iter().map(|e| e.ip()).collect();
 469                                         } else {
 470                                                 //TODO: Could optimize this one a bit
 471                                                 let mut intersection;
 472                                                 let mut intersection_set_ref = None;
 473                                                 for j in 0..64 {
 474                                                         if i & (1 << j) != 0 {
 475                                                                 if intersection_set_ref == None {
 476                                                                         intersection_set_ref = Some(&nodes.good_node_services[j]);
 477                                                                 } else {
 478                                                                         let new_intersection = intersection_set_ref.unwrap()
 479                                                                                 .intersection(&nodes.good_node_services[j]).map(|e| (*e).clone()).collect();
 480                                                                         intersection = Some(new_intersection);
 481                                                                         intersection_set_ref = Some(intersection.as_ref().unwrap());
 482                                                                 }
 483                                                         }
 484                                                 }
 485                                                 v4_set = intersection_set_ref.unwrap().iter()
 486                                                         .filter(|e| e.is_ipv4() && e.port() == 8333)
 487                                                         .choose_multiple(&mut rng, 21).iter().map(|e| e.ip()).collect();
 488                                                 v6_set = intersection_set_ref.unwrap().iter()
 489                                                         .filter(|e| e.is_ipv6() && e.port() == 8333)
 490                                                         .choose_multiple(&mut rng, 12).iter().map(|e| e.ip()).collect();
 491                                         }
 492                                         for a in v4_set {
 493                                                 dns_buff += &format!("x{:x}.dnsseed\tIN\tA\t{}\n", i, a);
 494                                         }
 495                                         for a in v6_set {
 496                                                 dns_buff += &format!("x{:x}.dnsseed\tIN\tAAAA\t{}\n", i, a);
 497                                         }
 498                                 }
 499                         }
 500                         write_all(f, dns_buff)
 501                 }).and_then(|(mut f, _)| {
 502                         f.poll_sync_all()
 503                 }).and_then(|_| {
 504                         tokio::fs::rename(dns_file.clone() + ".tmp", dns_file)
 505                 });
 506
 507                 settings_future.join3(nodes_future, dns_future).then(|_| { future::ok(()) })
 508         }
 509
 510         pub fn get_next_scan_nodes(&self) -> Vec<SocketAddr> {
 511                 let results = 30 * self.get_u64(U64Setting::ConnsPerSec) as usize;
 512                 let per_bucket_results = results / (AddressState::get_count() as usize);
 513                 let mut res = Vec::with_capacity(results);
 514                 let cur_time = Instant::now();
 515
 516                 {
 517                         let mut nodes = self.nodes.write().unwrap();
 518                         for (idx, state_nodes) in nodes.state_next_scan.iter_mut().enumerate() {
 519                                 let cmp_time = cur_time - Duration::from_secs(self.get_u64(U64Setting::RescanInterval(AddressState::from_num(idx as u8).unwrap())));
 520                                 let split_point = cmp::min(cmp::min(results - res.len(), (per_bucket_results * (idx + 1)) - res.len()),
 521                                                 state_nodes.binary_search_by(|a| a.0.cmp(&cmp_time)).unwrap_or_else(|idx| idx));
 522                                 let mut new_nodes = state_nodes.split_off(split_point);
 523                                 mem::swap(&mut new_nodes, state_nodes);
 524                                 for (_, node) in new_nodes.drain(..) {
 525                                         res.push(node);
 526                                 }
 527                         }
 528                 }
 529                 res.shuffle(&mut thread_rng());
 530                 res
 531         }
 532 }