From 7b8f9beedae4472b51a01656d12d6c6a9cb71122 Mon Sep 17 00:00:00 2001
From: Quentin McGaw <quentin.mcgaw@gmail.com>
Date: Tue, 15 Oct 2024 14:03:06 +0000
Subject: [PATCH] wip

---
 internal/vpn/interfaces.go                |  1 +
 internal/wireguard/netlinker.go           |  1 +
 internal/wireguard/netlinker_mock_test.go | 15 +++++++++++++++
 internal/wireguard/rule.go                | 13 +++++++++++++
 4 files changed, 30 insertions(+)

diff --git a/internal/vpn/interfaces.go b/internal/vpn/interfaces.go
index 68103690b..11b8fa621 100644
--- a/internal/vpn/interfaces.go
+++ b/internal/vpn/interfaces.go
@@ -72,6 +72,7 @@ type Router interface {
 type Ruler interface {
 	RuleAdd(rule netlink.Rule) error
 	RuleDel(rule netlink.Rule) error
+	RuleList(family int) (rules []netlink.Rule, err error)
 }
 
 type Linker interface {
diff --git a/internal/wireguard/netlinker.go b/internal/wireguard/netlinker.go
index 6b077016b..f4dbd161b 100644
--- a/internal/wireguard/netlinker.go
+++ b/internal/wireguard/netlinker.go
@@ -20,6 +20,7 @@ type Router interface {
 type Ruler interface {
 	RuleAdd(rule netlink.Rule) error
 	RuleDel(rule netlink.Rule) error
+	RuleList(family int) ([]netlink.Rule, error)
 }
 
 type Linker interface {
diff --git a/internal/wireguard/netlinker_mock_test.go b/internal/wireguard/netlinker_mock_test.go
index 124a659b7..ba0cd313e 100644
--- a/internal/wireguard/netlinker_mock_test.go
+++ b/internal/wireguard/netlinker_mock_test.go
@@ -207,3 +207,18 @@ func (mr *MockNetLinkerMockRecorder) RuleDel(arg0 interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "RuleDel", reflect.TypeOf((*MockNetLinker)(nil).RuleDel), arg0)
 }
+
+// RuleList mocks base method.
+func (m *MockNetLinker) RuleList(arg0 int) ([]netlink.Rule, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "RuleList", arg0)
+	ret0, _ := ret[0].([]netlink.Rule)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// RuleList indicates an expected call of RuleList.
+func (mr *MockNetLinkerMockRecorder) RuleList(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "RuleList", reflect.TypeOf((*MockNetLinker)(nil).RuleList), arg0)
+}
diff --git a/internal/wireguard/rule.go b/internal/wireguard/rule.go
index 7586b11aa..1f7b3e243 100644
--- a/internal/wireguard/rule.go
+++ b/internal/wireguard/rule.go
@@ -2,6 +2,7 @@ package wireguard
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/qdm12/gluetun/internal/netlink"
 )
@@ -16,6 +17,18 @@ func (w *Wireguard) addRule(rulePriority int, firewallMark uint32,
 	rule.Table = int(firewallMark)
 	rule.Family = family
 	if err := w.netlink.RuleAdd(rule); err != nil {
+		if strings.Contains(err.Error(), "file exists") {
+			rules, listErr := w.netlink.RuleList(family)
+			if listErr != nil {
+				return nil, fmt.Errorf("listing rules for family %d due to %q: %w",
+					family, err, listErr)
+			}
+			ruleStrings := make([]string, len(rules))
+			for i := range rules {
+				ruleStrings[i] = rules[i].String()
+			}
+			w.logger.Info("existing rules are:\n" + strings.Join(ruleStrings, "\n"))
+		}
 		return nil, fmt.Errorf("adding rule %s: %w", rule, err)
 	}