From 6975177d056d0deca9ebed18fbb0eb55359c6dc9 Mon Sep 17 00:00:00 2001
From: garwah <14845405+garwahl@users.noreply.github.com>
Date: Sat, 21 Sep 2024 20:17:42 +1000
Subject: [PATCH] Add new NetIf variant to NatResolver for IP resolution via
 network interface (#10922)

Co-authored-by: garwah <garwah@garwah>
Co-authored-by: Emilia Hane <emiliaha95@gmail.com>
Co-authored-by: Matthias Seitz <matthias.seitz@outlook.de>
---
 Cargo.lock                |  1 +
 crates/net/nat/Cargo.toml |  1 +
 crates/net/nat/src/lib.rs | 13 +++++++++++++
 3 files changed, 15 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 6fbb2607fbea..0057a70c2ad5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -7547,6 +7547,7 @@ dependencies = [
  "serde_with",
  "thiserror",
  "tokio",
+ "tracing",
 ]
 
 [[package]]
diff --git a/crates/net/nat/Cargo.toml b/crates/net/nat/Cargo.toml
index 99f209616779..6a072e491a63 100644
--- a/crates/net/nat/Cargo.toml
+++ b/crates/net/nat/Cargo.toml
@@ -18,6 +18,7 @@ serde_with = { workspace = true, optional = true }
 thiserror.workspace = true
 tokio = { workspace = true, features = ["time"] }
 if-addrs.workspace = true
+tracing.workspace = true
 
 [dev-dependencies]
 reth-tracing.workspace = true
diff --git a/crates/net/nat/src/lib.rs b/crates/net/nat/src/lib.rs
index e58edae05c81..9925e84fe25c 100644
--- a/crates/net/nat/src/lib.rs
+++ b/crates/net/nat/src/lib.rs
@@ -25,7 +25,9 @@ use std::{
     task::{Context, Poll},
     time::Duration,
 };
+use tracing::error;
 
+use crate::net_if::resolve_net_if_ip;
 #[cfg(feature = "serde")]
 use serde_with::{DeserializeFromStr, SerializeDisplay};
 
@@ -48,6 +50,8 @@ pub enum NatResolver {
     PublicIp,
     /// Use the given [`IpAddr`]
     ExternalIp(IpAddr),
+    /// Resolve external IP via the network interface.
+    NetIf,
     /// Resolve nothing
     None,
 }
@@ -66,6 +70,7 @@ impl fmt::Display for NatResolver {
             Self::Upnp => f.write_str("upnp"),
             Self::PublicIp => f.write_str("publicip"),
             Self::ExternalIp(ip) => write!(f, "extip:{ip}"),
+            Self::NetIf => f.write_str("netif"),
             Self::None => f.write_str("none"),
         }
     }
@@ -91,6 +96,7 @@ impl FromStr for NatResolver {
             "upnp" => Self::Upnp,
             "none" => Self::None,
             "publicip" | "public-ip" => Self::PublicIp,
+            "netif" => Self::NetIf,
             s => {
                 let Some(ip) = s.strip_prefix("extip:") else {
                     return Err(ParseNatResolverError::UnknownVariant(format!(
@@ -185,6 +191,13 @@ pub async fn external_addr_with(resolver: NatResolver) -> Option<IpAddr> {
     match resolver {
         NatResolver::Any | NatResolver::Upnp | NatResolver::PublicIp => resolve_external_ip().await,
         NatResolver::ExternalIp(ip) => Some(ip),
+        NatResolver::NetIf => match resolve_net_if_ip(DEFAULT_NET_IF_NAME) {
+            Ok(ip) => Some(ip),
+            Err(err) => {
+                error!("Failed to resolve network interface IP: {}", err);
+                None
+            }
+        },
         NatResolver::None => None,
     }
 }