Config option to set DNS resolver

config.json

@@ -1,4 +1,5 @@
 {
 	"ListenAddress": "127.0.0.1:3128",
-	"ListenType": "tcp4"
+	"ListenType": "tcp4",
+	"DNSResolver": "192.168.1.1:53"
 }

internal/conf/config.go

@@ -4,4 +4,5 @@ type Config struct {
 	ListenAddress string // Address to listen on, passed to net.Listen
 	ListenType    string // Type of network to listen on, passed to net.Listen. One of tcp, tcp4 and tcp6
 
+	DNSResolver string // Address to send UDP & TCP DNS requests to. If set, the Go resolver will also be forced.
 }

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -8,6 +9,7 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"edgaru089.ink/go/regolith/internal/conf"
 	"edgaru089.ink/go/regolith/internal/http"
@@ -44,6 +46,16 @@ func main() {
 		}
 	}
 
+	if len(conf.DNSResolver) != 0 {
+		dialer := &net.Dialer{
+			Timeout: time.Second * 10,
+		}
+		net.DefaultResolver.PreferGo = true
+		net.DefaultResolver.Dial = func(ctx context.Context, network, address string) (net.Conn, error) {
+			return dialer.Dial(network, conf.DNSResolver)
+		}
+	}
+
 	listener, err := net.Listen(conf.ListenType, conf.ListenAddress)
 	if err != nil {
 		panic(err)