From 58e16661fe975942e0e07a2aa86637597cda66a0 Mon Sep 17 00:00:00 2001
From: Vladislav Yarmak <vladislav@vm-0.com>
Date: Thu, 1 Aug 2024 18:22:11 +0300
Subject: [PATCH] close resolvers properly

---
 go.mod      |  2 ++
 go.sum      |  4 ++++
 main.go     |  4 ++++
 resolver.go | 14 ++++++++++++++
 4 files changed, 24 insertions(+)

diff --git a/go.mod b/go.mod
index 066adbf..c0549c2 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.22.5
 require (
 	github.com/AdguardTeam/dnsproxy v0.72.2
 	github.com/Snawoot/go-http-digest-auth-client v1.1.3
+	github.com/hashicorp/go-multierror v1.1.1
 	golang.org/x/net v0.27.0
 )
 
@@ -16,6 +17,7 @@ require (
 	github.com/ameshkov/dnsstamps v1.0.3 // indirect
 	github.com/go-task/slim-sprig/v3 v3.0.0 // indirect
 	github.com/google/pprof v0.0.0-20240727154555-813a5fbdbec8 // indirect
+	github.com/hashicorp/errwrap v1.0.0 // indirect
 	github.com/miekg/dns v1.1.61 // indirect
 	github.com/onsi/ginkgo/v2 v2.19.1 // indirect
 	github.com/quic-go/qpack v0.4.0 // indirect
diff --git a/go.sum b/go.sum
index 8346795..5376bd0 100644
--- a/go.sum
+++ b/go.sum
@@ -22,6 +22,10 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/pprof v0.0.0-20240727154555-813a5fbdbec8 h1:FKHo8hFI3A+7w0aUQuYXQ+6EN5stWmeY/AZqtM8xk9k=
 github.com/google/pprof v0.0.0-20240727154555-813a5fbdbec8/go.mod h1:K1liHPHnj73Fdn/EKuT8nrFqBihUSKXoLYU0BuatOYo=
+github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/miekg/dns v1.1.61 h1:nLxbwF3XxhwVSm8g9Dghm9MHPaUZuqhPiGL+675ZmEs=
 github.com/miekg/dns v1.1.61/go.mod h1:mnAarhS3nWaW+NVP2wTkYVIZyHNJ098SJZUki3eykwQ=
 github.com/onsi/ginkgo/v2 v2.19.1 h1:QXgq3Z8Crl5EL1WBAC98A5sEBHARrAJNzAmMxzLcRF0=
diff --git a/main.go b/main.go
index d4c3565..b322d2f 100644
--- a/main.go
+++ b/main.go
@@ -210,6 +210,10 @@ func run() int {
 			addrs, err := func() ([]netip.Addr, error) {
 				ctx, cancel := context.WithTimeout(context.Background(), args.timeout)
 				defer cancel()
+				defer func() {
+					resolver = nil
+				}()
+				defer resolver.Close()
 				return resolver.LookupNetIP(ctx, "ip4", API_DOMAIN)
 			}()
 			if err != nil {
diff --git a/resolver.go b/resolver.go
index f460e4e..76ab612 100644
--- a/resolver.go
+++ b/resolver.go
@@ -3,10 +3,12 @@ package main
 import (
 	"context"
 	"fmt"
+	"io"
 	"net/netip"
 	"time"
 
 	"github.com/AdguardTeam/dnsproxy/upstream"
+	"github.com/hashicorp/go-multierror"
 )
 
 type Resolver struct {
@@ -36,3 +38,15 @@ func NewResolver(addresses []string, timeout time.Duration) (*Resolver, error) {
 func (r *Resolver) LookupNetIP(ctx context.Context, network string, host string) (addrs []netip.Addr, err error) {
 	return r.resolvers.LookupNetIP(ctx, network, host)
 }
+
+func (r *Resolver) Close() error {
+	var res error
+	for _, resolver := range r.resolvers {
+		if closer, ok := resolver.(io.Closer); ok {
+			if err := closer.Close(); err != nil {
+				res = multierror.Append(res, err)
+			}
+		}
+	}
+	return res
+}