[common] Filter seed by features supported.

client/src/client.rs

@@ -301,7 +301,7 @@ impl<R: Reactor<Publisher>> Client<R> {
         if config.protocol.connect.is_empty() && peers.is_empty() {
             log::info!("Address book is empty. Trying DNS seeds..");
             peers.seed(
-                network.seeds().iter().map(|s| (*s, network.port())),
+                network.seeds().iter().map(|s| (s.as_str(), network.port())),
                 Source::Dns,
             )?;
             peers.flush()?;

common/src/network.rs

@@ -1,4 +1,5 @@
 //! Bitcoin peer network. Eg. *Mainnet*.
+use std::vec;
 
 use bitcoin::blockdata::block::{Block, BlockHeader};
 use bitcoin::consensus::params::Params;
@@ -99,29 +100,52 @@ impl Network {
         }
     }
 
+    /// Return the flag generated by the composition of the service flags.
+    fn service_flags(&self, services: &[ServiceFlags]) -> String {
+        let combination: u64 = services.iter().map(|service| service.as_u64()).sum();
+        format!("x{:x}", combination)
+    }
+
     /// DNS seeds. Used to bootstrap the client's address book.
-    pub fn seeds(&self) -> &[&str] {
-        match self {
-            Network::Mainnet => &[
-                "seed.bitcoin.sipa.be",          // Pieter Wuille
-                "dnsseed.bluematt.me",           // Matt Corallo
-                "dnsseed.bitcoin.dashjr.org",    // Luke Dashjr
-                "seed.bitcoinstats.com",         // Christian Decker
-                "seed.bitcoin.jonasschnelli.ch", // Jonas Schnelli
-                "seed.btc.petertodd.org",        // Peter Todd
-                "seed.bitcoin.sprovoost.nl",     // Sjors Provoost
-                "dnsseed.emzy.de",               // Stephan Oeste
-                "seed.bitcoin.wiz.biz",          // Jason Maurice
-                "seed.cloudhead.io",             // Alexis Sellier
+    pub fn seeds(&self) -> Vec<String> {
+        let seed_list = match self {
+            Network::Mainnet => vec![
+                "seed.bitcoin.sipa.be",       // Pieter Wuille
+                "dnsseed.bluematt.me",        // Matt Corallo
+                "dnsseed.bitcoin.dashjr.org", // Luke Dashjr
+                "seed.bitcoinstats.com",      // Christian Decker
+                //                "seed.bitcoin.jonasschnelli.ch", // Jonas Schnelli
+                "seed.btc.petertodd.org",    // Peter Todd
+                "seed.bitcoin.sprovoost.nl", // Sjors Provoost
+                "dnsseed.emzy.de",           // Stephan Oeste
+                "seed.bitcoin.wiz.biz",      // Jason Maurice
+                "seed.cloudhead.io",         // Alexis Sellier
             ],
-            Network::Testnet => &[
+            Network::Testnet => vec![
                 "testnet-seed.bitcoin.jonasschnelli.ch",
                 "seed.tbtc.petertodd.org",
                 "seed.testnet.bitcoin.sprovoost.nl",
                 "testnet-seed.bluematt.me",
             ],
-            Network::Regtest => &[], // No seeds
+            Network::Regtest => vec![], // No seeds
+        };
+
+        // We index this array by a step = 2, so
+        // each new seed has the following rules
+        // index i: Contains the dns with service flag
+        // index i + 1 Contains the pure dns without service flag
+        // the step size it is the number of feature typology supported
+        // in this case are 2, because we support ANY, and NETWORK + COMPACT_FILTERS
+        let mut feature_seeds = Vec::new();
+        let flag = self.service_flags(&[ServiceFlags::NETWORK, ServiceFlags::COMPACT_FILTERS]);
+        for seed in seed_list.iter() {
+            // Adding dns seed with service flag
+            let feature_seed = format!("{}.{}", flag, seed);
+            feature_seeds.push(feature_seed);
+            // Adding dns seed without service flag
+            feature_seeds.push(seed.to_string());
         }
+        feature_seeds
     }
 }
 

common/src/p2p/peer.rs

@@ -1,12 +1,12 @@
 //! Shared peer types.
 
+use log::debug;
 use std::io;
 use std::net;
 
-use microserde as serde;
-
 use bitcoin::network::address::Address;
 use bitcoin::network::constants::ServiceFlags;
+use microserde as serde;
 
 use crate::block::time::LocalTime;
 
@@ -40,15 +40,19 @@ pub trait Store {
 
     /// Seed the peer store with addresses.
     /// Fails if *none* of the seeds could be resolved to addresses.
-    fn seed<S: net::ToSocketAddrs>(
+    fn seed<S: net::ToSocketAddrs + std::fmt::Debug>(
         &mut self,
-        seeds: impl Iterator<Item = S>,
+        mut seeds: impl Iterator<Item = S>,
         source: Source,
     ) -> io::Result<()> {
-        let mut error = None;
+        let mut fail = false;
         let mut success = false;
-
-        for seed in seeds {
+        // TODO: Introduce a step that mean how many combination
+        // of services flags we need to try before check the seeds without
+        // services flags.
+        // for the moment it is 2, but we need a more general solution.
+        while let Some(seed) = seeds.next() {
+            debug!("Resolving DNS seed {:?}", seed);
             match seed.to_socket_addrs() {
                 Ok(addrs) => {
                     success = true;
@@ -62,18 +66,23 @@ pub trait Store {
                             ),
                         );
                     }
+                    // skip the item in position +1 because it is a recovered seed
+                    // in case we receive a failure in match branch
+                    if !fail {
+                        seeds.next();
+                    }
+                    fail = false;
+                }
+                Err(err) => {
+                    debug!("Error During DNS seed resolution {:?}", err);
+                    fail = true;
                 }
-                Err(err) => error = Some(err),
             }
         }
-
-        if success {
-            return Ok(());
-        }
-        if let Some(err) = error {
+        if !success {
             return Err(io::Error::new(
                 io::ErrorKind::Other,
-                format!("seeds failed to resolve: {}", err),
+                "All seeds failed to resolve",
             ));
         }
         Ok(())