+ DNS: "dns.upstream_dns_file" setting

AGHTechDoc.md

@@ -986,6 +986,7 @@ Response:
 
 	{
 		"upstream_dns": ["tls://...", ...],
+		"upstream_dns_file": "",
 		"bootstrap_dns": ["1.2.3.4", ...],
 
 		"protection_enabled": true | false,
@@ -1011,6 +1012,7 @@ Request:
 
 	{
 		"upstream_dns": ["tls://...", ...],
+		"upstream_dns_file": "",
 		"bootstrap_dns": ["1.2.3.4", ...],
 
 		"protection_enabled": true | false,

dnsforward/config.go

@@ -5,6 +5,7 @@ import (
 	"crypto/x509"
 	"errors"
 	"fmt"
+	"io/ioutil"
 	"net"
 	"net/http"
 	"sort"
@@ -13,6 +14,7 @@ import (
 	"github.com/joomcode/errorx"
 
 	"github.com/AdguardTeam/AdGuardHome/dnsfilter"
+	"github.com/AdguardTeam/AdGuardHome/util"
 	"github.com/AdguardTeam/dnsproxy/proxy"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 )
@@ -56,6 +58,7 @@ type FilteringConfig struct {
 	// --
 
 	UpstreamDNS         []string `yaml:"upstream_dns"`
+	UpstreamDNSFileName string   `yaml:"upstream_dns_file"`
 	BootstrapDNS        []string `yaml:"bootstrap_dns"` // a list of bootstrap DNS for DoH and DoT (plain DNS only)
 	AllServers          bool     `yaml:"all_servers"`   // if true, parallel queries to all configured upstream servers are enabled
 	FastestAddr         bool     `yaml:"fastest_addr"`  // use Fastest Address algorithm
@@ -215,7 +218,22 @@ func (s *Server) initDefaultSettings() {
 
 // prepareUpstreamSettings - prepares upstream DNS server settings
 func (s *Server) prepareUpstreamSettings() error {
-	upstreamConfig, err := proxy.ParseUpstreamsConfig(s.conf.UpstreamDNS, s.conf.BootstrapDNS, DefaultTimeout)
+	var upstreams []string
+	if s.conf.UpstreamDNSFileName != "" {
+		data, err := ioutil.ReadFile(s.conf.UpstreamDNSFileName)
+		if err != nil {
+			return err
+		}
+		d := string(data)
+		for len(d) != 0 {
+			s := util.SplitNext(&d, '\n')
+			upstreams = append(upstreams, s)
+		}
+		log.Debug("DNS: using %d upstream servers from file %s", len(upstreams), s.conf.UpstreamDNSFileName)
+	} else {
+		upstreams = s.conf.UpstreamDNS
+	}
+	upstreamConfig, err := proxy.ParseUpstreamsConfig(upstreams, s.conf.BootstrapDNS, DefaultTimeout)
 	if err != nil {
 		return fmt.Errorf("DNS: proxy.ParseUpstreamsConfig: %s", err)
 	}

dnsforward/dnsforward_http.go

@@ -23,6 +23,7 @@ func httpError(r *http.Request, w http.ResponseWriter, code int, format string,
 
 type dnsConfigJSON struct {
 	Upstreams     []string `json:"upstream_dns"`
+	UpstreamsFile string   `json:"upstream_dns_file"`
 	Bootstraps    []string `json:"bootstrap_dns"`
 
 	ProtectionEnabled bool   `json:"protection_enabled"`
@@ -43,6 +44,7 @@ func (s *Server) handleGetConfig(w http.ResponseWriter, r *http.Request) {
 	resp := dnsConfigJSON{}
 	s.RLock()
 	resp.Upstreams = stringArrayDup(s.conf.UpstreamDNS)
+	resp.UpstreamsFile = s.conf.UpstreamDNSFileName
 	resp.Bootstraps = stringArrayDup(s.conf.BootstrapDNS)
 
 	resp.ProtectionEnabled = s.conf.ProtectionEnabled
@@ -157,6 +159,11 @@ func (s *Server) handleSetConfig(w http.ResponseWriter, r *http.Request) {
 		restart = true
 	}
 
+	if js.Exists("upstream_dns_file") {
+		s.conf.UpstreamDNSFileName = req.UpstreamsFile
+		restart = true
+	}
+
 	if js.Exists("bootstrap_dns") {
 		s.conf.BootstrapDNS = req.Bootstraps
 		restart = true

openapi/openapi.yaml

@@ -997,6 +997,8 @@ components:
                     example:
                         - tls://1.1.1.1
                         - tls://1.0.0.1
+                upstream_dns_file:
+                    type: string
                 protection_enabled:
                     type: boolean
                 dhcp_available: