From 2b1502e3e3a3f2cd353eb3448c52e1c20bb4ecff Mon Sep 17 00:00:00 2001
From: Yevhenii Babichenko <eugene.babichenko@iohk.io>
Date: Thu, 7 May 2020 15:16:55 +0300
Subject: [PATCH] dns: better error reporting

---
 jormungandr-lib/src/multiaddr.rs      | 59 +++++++++++++++++----------
 jormungandr/src/settings/start/mod.rs | 24 +++++------
 2 files changed, 49 insertions(+), 34 deletions(-)

diff --git a/jormungandr-lib/src/multiaddr.rs b/jormungandr-lib/src/multiaddr.rs
index 9f1678787f..7217fd2f9d 100644
--- a/jormungandr-lib/src/multiaddr.rs
+++ b/jormungandr-lib/src/multiaddr.rs
@@ -3,6 +3,19 @@ use std::{
     io,
     net::{SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs},
 };
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("Not enough components in multiaddr")]
+    InvalidMultiaddr,
+    #[error("Cannot find DNS record")]
+    NotFound(#[source] io::Error),
+    #[error("No IPv4 address found")]
+    NoIP4,
+    #[error("No IPv6 address found")]
+    NoIP6,
+}
 
 pub fn multiaddr_to_socket_addr(addr: &Multiaddr) -> Option<SocketAddr> {
     let mut components = addr.iter();
@@ -21,30 +34,34 @@ pub fn multiaddr_to_socket_addr(addr: &Multiaddr) -> Option<SocketAddr> {
     }
 }
 
-pub fn multiaddr_resolve_dns(addr: Multiaddr) -> io::Result<Option<Multiaddr>> {
+pub fn multiaddr_resolve_dns(addr: &Multiaddr) -> Result<Option<Multiaddr>, Error> {
     let mut components = addr.iter();
 
-    let ip_or_fqdn = if let Some(ip) = components.next() {
-        ip
-    } else {
-        return Ok(None);
-    };
-
-    let port = if let Some(AddrComponent::TCP(port)) = components.next() {
-        port
-    } else {
-        return Ok(None);
-    };
+    let ip_or_fqdn = components.next().ok_or(Error::InvalidMultiaddr)?;
+    let port = components
+        .next()
+        .and_then(|ac| {
+            if let AddrComponent::TCP(port) = ac {
+                Some(port)
+            } else {
+                None
+            }
+        })
+        .ok_or(Error::InvalidMultiaddr)?;
 
-    let maybe_socket_addr = match ip_or_fqdn {
-        AddrComponent::DNS4(fqdn) => (fqdn.as_ref(), port)
-            .to_socket_addrs()?
-            .find(|addr| matches!(addr, SocketAddr::V4(_))),
-        AddrComponent::DNS6(fqdn) => (fqdn.as_ref(), port)
-            .to_socket_addrs()?
-            .find(|addr| matches!(addr, SocketAddr::V6(_))),
-        _ => return Ok(Some(addr)),
+    let socket_addr = match ip_or_fqdn {
+        AddrComponent::DNS4(fqdn) => (fqdn.as_str(), port)
+            .to_socket_addrs()
+            .map_err(Error::NotFound)?
+            .find(|addr| matches!(addr, SocketAddr::V4(_)))
+            .ok_or(Error::NoIP4)?,
+        AddrComponent::DNS6(fqdn) => (fqdn.as_str(), port)
+            .to_socket_addrs()
+            .map_err(Error::NotFound)?
+            .find(|addr| matches!(addr, SocketAddr::V6(_)))
+            .ok_or(Error::NoIP6)?,
+        _ => return Ok(None),
     };
 
-    Ok(maybe_socket_addr.map(|socket_addr| socket_addr.to_multiaddr().unwrap()))
+    Ok(Some(socket_addr.to_multiaddr().unwrap()))
 }
diff --git a/jormungandr/src/settings/start/mod.rs b/jormungandr/src/settings/start/mod.rs
index dcb92b680b..96783ea13c 100644
--- a/jormungandr/src/settings/start/mod.rs
+++ b/jormungandr/src/settings/start/mod.rs
@@ -196,7 +196,7 @@ fn generate_network(
     config: &Option<Config>,
     logger: &Logger,
 ) -> Result<network::Configuration, Error> {
-    use jormungandr_lib::multiaddr::*;
+    use jormungandr_lib::multiaddr::{multiaddr_resolve_dns, multiaddr_to_socket_addr};
 
     let (mut p2p, http_fetch_block0_service, skip_bootstrap, bootstrap_from_trusted_peers) =
         if let Some(cfg) = config {
@@ -220,25 +220,23 @@ fn generate_network(
 
     p2p.trusted_peers.as_mut().map(|peers| {
         *peers = peers.iter().filter_map(|peer| {
-            let address = match multiaddr_resolve_dns(peer.address.multi_address().clone()) {
-                Ok(Some(addr)) => {
-                    info!(logger, "DNS resolved"; "fqdn" => peer.address.multi_address().to_string(), "resolved" => addr.to_string());
-                    addr
+            match multiaddr_resolve_dns(peer.address.multi_address()) {
+                Ok(Some(address)) => {
+                    info!(logger, "DNS resolved"; "fqdn" => peer.address.multi_address().to_string(), "resolved" => address.to_string());
+                    let address = poldercast::Address::from(address);
+                    Some(config::TrustedPeer {
+                        address,
+                        id: peer.id.clone(),
+                    })
                 }
                 Ok(None) => {
-                    warn!(logger, "failed to resolve DNS"; "fqdn" => peer.address.multi_address().to_string());
-                    return None;
+                    Some(peer.clone())
                 },
                 Err(e) => {
                     warn!(logger, "failed to resolve dns"; "fqdn" => peer.address.multi_address().to_string(), "error" => e.to_string());
                     return None;
                 }
-            };
-            let address = poldercast::Address::from(address);
-            Some(config::TrustedPeer {
-                address,
-                id: peer.id.clone(),
-            })
+            }
         }).collect();
     });