From 35ab1b15865e971c41c76d0a71d2901f58135164 Mon Sep 17 00:00:00 2001
From: Victor Shih <vcshih@gmail.com>
Date: Mon, 5 Feb 2024 20:05:37 +0800
Subject: [PATCH] feature: better Address in use error message. (#6397)

---
 crates/net/network/src/error.rs     | 30 ++++++++++++++++++++--
 crates/rpc/rpc-builder/src/error.rs | 39 ++++++++++++++++++++++++++++-
 2 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/crates/net/network/src/error.rs b/crates/net/network/src/error.rs
index ae8b485cad..34fd22f3fa 100644
--- a/crates/net/network/src/error.rs
+++ b/crates/net/network/src/error.rs
@@ -9,7 +9,7 @@ use reth_eth_wire::{
 use std::{fmt, io, io::ErrorKind, net::SocketAddr};
 
 /// Service kind.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Copy, Clone)]
 pub enum ServiceKind {
     /// Listener service.
     Listener(SocketAddr),
@@ -17,6 +17,16 @@ pub enum ServiceKind {
     Discovery(SocketAddr),
 }
 
+impl ServiceKind {
+    /// Returns the appropriate flags for each variant.
+    pub fn flags(&self) -> &'static str {
+        match self {
+            ServiceKind::Listener(_) => "--port",
+            ServiceKind::Discovery(_) => "--discovery.port",
+        }
+    }
+}
+
 impl fmt::Display for ServiceKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
@@ -33,7 +43,7 @@ pub enum NetworkError {
     #[error(transparent)]
     Io(#[from] io::Error),
     /// Error when an address is already in use.
-    #[error("address {kind} is already in use (os error 98)")]
+    #[error("address {kind} is already in use (os error 98). Choose a different port using {}", kind.flags())]
     AddressAlreadyInUse {
         /// Service kind.
         kind: ServiceKind,
@@ -269,6 +279,7 @@ impl SessionError for io::Error {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::net::{Ipv4Addr, SocketAddrV4};
 
     #[test]
     fn test_is_fatal_disconnect() {
@@ -295,4 +306,19 @@ mod tests {
         ));
         assert_eq!(err.should_backoff(), Some(BackoffKind::Low));
     }
+
+    #[test]
+    fn test_address_in_use_message() {
+        let addr = SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 1234));
+        let kinds = [ServiceKind::Discovery(addr), ServiceKind::Listener(addr)];
+
+        for kind in &kinds {
+            let err = NetworkError::AddressAlreadyInUse {
+                kind: *kind,
+                error: io::Error::from(ErrorKind::AddrInUse),
+            };
+
+            assert!(err.to_string().contains(kind.flags()));
+        }
+    }
 }
diff --git a/crates/rpc/rpc-builder/src/error.rs b/crates/rpc/rpc-builder/src/error.rs
index 5b13e78824..a1d6994f89 100644
--- a/crates/rpc/rpc-builder/src/error.rs
+++ b/crates/rpc/rpc-builder/src/error.rs
@@ -17,6 +17,18 @@ pub enum ServerKind {
     Auth(SocketAddr),
 }
 
+impl ServerKind {
+    /// Returns the appropriate flags for each variant.
+    pub fn flags(&self) -> &'static str {
+        match self {
+            ServerKind::Http(_) => "--http.port",
+            ServerKind::WS(_) => "--ws.port",
+            ServerKind::WsHttp(_) => "--ws.port and --http.port",
+            ServerKind::Auth(_) => "--authrpc.port",
+        }
+    }
+}
+
 impl std::fmt::Display for ServerKind {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -35,7 +47,7 @@ pub enum RpcError {
     #[error(transparent)]
     RpcError(#[from] JsonRpseeError),
     /// Address already in use.
-    #[error("address {kind} is already in use (os error 98)")]
+    #[error("address {kind} is already in use (os error 98). Choose a different port using {}", kind.flags())]
     AddressAlreadyInUse {
         /// Server kind.
         kind: ServerKind,
@@ -96,3 +108,28 @@ pub enum WsHttpSamePortError {
         ws_modules: Vec<RethRpcModule>,
     },
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::net::{Ipv4Addr, SocketAddrV4};
+    #[test]
+    fn test_address_in_use_message() {
+        let addr = SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 1234));
+        let kinds = [
+            ServerKind::Http(addr),
+            ServerKind::WS(addr),
+            ServerKind::WsHttp(addr),
+            ServerKind::Auth(addr),
+        ];
+
+        for kind in &kinds {
+            let err = RpcError::AddressAlreadyInUse {
+                kind: *kind,
+                error: io::Error::from(ErrorKind::AddrInUse),
+            };
+
+            assert!(err.to_string().contains(kind.flags()));
+        }
+    }
+}