dns.rs

//
// Copyright 2018-2019 Tamas Blummer
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//!
//! # Bitcoin DNS lookup
//!
//! Find initial Bitcoin node addresses by looking up trusted DNS servers
//! This should only be used if the peer has no own knowledge where to find a node of the
//! Bitcoin network
//!
//!

use bitcoin::network::constants::Network;
use log::{info, trace};
use std::net::{SocketAddr, ToSocketAddrs};

const MAIN_SEEDER: [&str; 9] = [
    "seed.bitcoin.sipa.be",
    "dnsseed.bluematt.me",
    "dnsseed.bitcoin.dashjr.org",
    "seed.bitcoinstats.com",
    "seed.bitcoin.jonasschnelli.ch",
    "seed.btc.petertodd.org",
    "seed.bitcoin.sprovoost.nl",
    "dnsseed.emzy.de",
    "seed.bitcoin.wiz.biz",
];

const TEST_SEEDER: [&str; 4] = [
    "testnet-seed.bitcoin.jonasschnelli.ch",
    "seed.tbtc.petertodd.org",
    "seed.testnet.bitcoin.sprovoost.nl",
    "testnet-seed.bluematt.me",
];

pub fn dns_seed(network: Network) -> Vec<SocketAddr> {
    let mut seeds = Vec::new();
    if network == Network::Bitcoin {
        info!("reaching out for DNS seed...");
        for seedhost in MAIN_SEEDER.iter() {
            if let Ok(lookup) = (*seedhost, 8333).to_socket_addrs() {
                for host in lookup {
                    seeds.push(host);
                }
            } else {
                trace!("{} did not answer", seedhost);
            }
        }
        info!("received {} DNS seeds", seeds.len());
    }
    if network == Network::Testnet {
        info!("reaching out for DNS seed...");
        for seedhost in TEST_SEEDER.iter() {
            if let Ok(lookup) = (*seedhost, 18333).to_socket_addrs() {
                for host in lookup {
                    seeds.push(host);
                }
            } else {
                trace!("{} did not answer", seedhost);
            }
        }
        info!("received {} DNS seeds", seeds.len());
    }
    seeds
}