From 66ee10619b3d4d8dedce5d8f2a031109e7a746c9 Mon Sep 17 00:00:00 2001
From: Lyn <lynatic@noreply.localhost>
Date: Wed, 29 Jan 2025 16:39:17 +0100
Subject: [PATCH] add filter_force_ipv6 option that (only when being set)
 filters gossip endpoints by their version (false -> V4, true -> V6). this
 avoids mixups in setups where interfaces are separated by IP version.

---
 src/main.rs | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 4f8557f..c0688a1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -85,6 +85,7 @@ struct InterfaceSetting {
     name: String,
     /// Specify the external port that should be IGD forwarded to this Wireguard interface. Only used for IPv4.
     upnp_ext_port_v4: Option<u16>,
+    filter_force_ipv6: Option<bool>,
 }
 
 fn main() -> Result<()> {
@@ -657,7 +658,6 @@ impl State {
 
         Ok(())
     }
-
     fn setup_wg_peers(&mut self, daemon: &Daemon, i: usize) -> Result<()> {
         let now = time();
         for peer_cfg in daemon.config.peers.iter() {
@@ -737,6 +737,15 @@ impl State {
                         }
                     }
                     endpoints.sort();
+                    // if prefer_ipv6 option is set, strongly prefer addresses of chosen version
+                    if let Some(interface) = daemon.config.interfaces.iter().find(|ifsetting| ifsetting.name == peer_cfg.interface) {
+                        if let Some(filter_ipv6_only) = interface.filter_force_ipv6 {
+                            endpoints = endpoints.into_iter().filter(|(ep, _)| {
+                                ep.ip().is_ipv6() == filter_ipv6_only
+                            }).collect();
+                        }
+                    }
+
                     endpoints = endpoints
                         .into_iter()
                         .filter(|(ep, _)| {
@@ -750,7 +759,6 @@ impl State {
                     endpoints
                 }
             };
-
             if !endpoints.is_empty() {
                 let endpoint = endpoints[i % endpoints.len()].0;