From 7cd963e6bb7ad35458defc94f3c6a24eb24f249c Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Thu, 15 Aug 2019 18:48:39 +1000
Subject: [PATCH] Update bootstrapper libp2p address finding

---
 beacon_node/client/src/bootstrapper.rs | 31 +++++++++++++++++++++++++-
 beacon_node/client/src/config.rs       | 26 +++++++++------------
 beacon_node/src/main.rs                |  5 +++++
 beacon_node/src/run.rs                 |  7 +-----
 4 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/beacon_node/client/src/bootstrapper.rs b/beacon_node/client/src/bootstrapper.rs
index 1fd8f16592..2c8cf6afc2 100644
--- a/beacon_node/client/src/bootstrapper.rs
+++ b/beacon_node/client/src/bootstrapper.rs
@@ -1,5 +1,9 @@
-use eth2_libp2p::{Enr, Multiaddr};
+use eth2_libp2p::{
+    multiaddr::{Multiaddr, Protocol},
+    Enr,
+};
 use reqwest::{Error as HttpError, Url};
+use std::borrow::Cow;
 use std::net::Ipv4Addr;
 use types::{BeaconBlock, BeaconState, Checkpoint, EthSpec, Slot};
 use url::Host;
@@ -27,6 +31,31 @@ impl Bootstrapper {
         })
     }
 
+    pub fn best_effort_multiaddr(&self) -> Option<Multiaddr> {
+        let tcp_port = self.first_listening_tcp_port()?;
+
+        let mut multiaddr = Multiaddr::with_capacity(2);
+
+        match self.url.host()? {
+            Host::Ipv4(addr) => multiaddr.push(Protocol::Ip4(addr)),
+            Host::Domain(s) => multiaddr.push(Protocol::Dns4(Cow::Borrowed(s))),
+            _ => return None,
+        };
+
+        multiaddr.push(Protocol::Tcp(tcp_port));
+
+        Some(multiaddr)
+    }
+
+    fn first_listening_tcp_port(&self) -> Option<u16> {
+        self.listen_addresses().ok()?.iter().find_map(|multiaddr| {
+            multiaddr.iter().find_map(|protocol| match protocol {
+                Protocol::Tcp(port) => Some(port),
+                _ => None,
+            })
+        })
+    }
+
     pub fn server_ipv4_addr(&self) -> Option<Ipv4Addr> {
         match self.url.host()? {
             Host::Ipv4(addr) => Some(addr),
diff --git a/beacon_node/client/src/config.rs b/beacon_node/client/src/config.rs
index 5dd0eef52f..1a985fb4af 100644
--- a/beacon_node/client/src/config.rs
+++ b/beacon_node/client/src/config.rs
@@ -1,6 +1,5 @@
 use crate::{Bootstrapper, Eth2Config};
 use clap::ArgMatches;
-use eth2_libp2p::multiaddr::{Multiaddr, Protocol};
 use network::NetworkConfig;
 use serde_derive::{Deserialize, Serialize};
 use slog::{info, o, warn, Drain};
@@ -169,23 +168,18 @@ fn do_bootstrapping(config: &mut Config, server: String, log: &slog::Logger) ->
 
     config.network.boot_nodes.push(bootstrapper.enr()?);
 
-    if let Some(server_ip) = bootstrapper.server_ipv4_addr() {
-        let server_multiaddr: Multiaddr = bootstrapper
-            .listen_addresses()?
-            .first()
-            .ok_or_else(|| "Bootstrap peer returned an empty list of listen addresses")?
-            // Iterate through the components of the Multiaddr, replacing any Ipv4 address with the
-            // server address.
-            .iter()
-            .map(|protocol| match protocol {
-                Protocol::Ip4(_) => Protocol::Ip4(server_ip),
-                _ => protocol,
-            })
-            .collect::<Multiaddr>();
-
+    if let Some(server_multiaddr) = bootstrapper.best_effort_multiaddr() {
+        info!(
+            log,
+            "Estimated bootstrapper libp2p address";
+            "multiaddr" => format!("{:?}", server_multiaddr)
+        );
         config.network.libp2p_nodes.push(server_multiaddr);
     } else {
-        warn!(log, "Unable to determine bootstrap server Ipv4 address. Unable to add server as libp2p peer.");
+        warn!(
+            log,
+            "Unable to estimate a bootstrapper libp2p address, this node may not find any peers."
+        );
     }
 
     Ok(())
diff --git a/beacon_node/src/main.rs b/beacon_node/src/main.rs
index ae48f692b6..04366baa7a 100644
--- a/beacon_node/src/main.rs
+++ b/beacon_node/src/main.rs
@@ -237,6 +237,11 @@ fn main() {
 
     let mut log = slog::Logger::root(drain.fuse(), o!());
 
+    warn!(
+        log,
+        "Ethereum 2.0 is pre-release. This software is experimental."
+    );
+
     let data_dir = match matches
         .value_of("datadir")
         .and_then(|v| Some(PathBuf::from(v)))
diff --git a/beacon_node/src/run.rs b/beacon_node/src/run.rs
index c16d23e5f1..5066231d55 100644
--- a/beacon_node/src/run.rs
+++ b/beacon_node/src/run.rs
@@ -4,7 +4,7 @@ use client::{
 };
 use futures::sync::oneshot;
 use futures::Future;
-use slog::{error, info, warn};
+use slog::{error, info};
 use std::cell::RefCell;
 use std::path::Path;
 use std::path::PathBuf;
@@ -42,11 +42,6 @@ pub fn run_beacon_node(
 
     let other_client_config = client_config.clone();
 
-    warn!(
-        log,
-        "Ethereum 2.0 is pre-release. This software is experimental."
-    );
-
     info!(
         log,
         "BeaconNode init";