Fix #542 - Add Bootstrap DNS resolver settings

config.go

@@ -61,6 +61,7 @@ type dnsConfig struct {
 }
 
 var defaultDNS = []string{"tls://1.1.1.1", "tls://1.0.0.1"}
+var defaultBootstrap = []string{"1.1.1.1"}
 
 type tlsConfigSettings struct {
 	Enabled        bool   `yaml:"enabled" json:"enabled"`                               // Enabled is the encryption (DOT/DOH/HTTPS) status
@@ -114,7 +115,7 @@ var config = configuration{
 			QueryLogEnabled:    true,
 			Ratelimit:          20,
 			RefuseAny:          true,
-			BootstrapDNS:       "8.8.8.8:53",
+			BootstrapDNS:       defaultBootstrap,
 		},
 		UpstreamDNS: defaultDNS,
 	},

control.go

@@ -437,6 +437,45 @@ func checkDNS(input string) error {
 	return nil
 }
 
+func handleSetBootstrapDNS(w http.ResponseWriter, r *http.Request) {
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		errorText := fmt.Sprintf("Failed to read request body: %s", err)
+		log.Println(errorText)
+		http.Error(w, errorText, http.StatusBadRequest)
+		return
+	}
+	// if empty body -- user is asking for default servers
+	hosts := strings.Fields(string(body))
+
+	if len(hosts) == 0 {
+		config.DNS.BootstrapDNS = defaultBootstrap
+	} else {
+		config.DNS.BootstrapDNS = hosts
+	}
+
+	err = writeAllConfigs()
+	if err != nil {
+		errorText := fmt.Sprintf("Couldn't write config file: %s", err)
+		log.Println(errorText)
+		http.Error(w, errorText, http.StatusInternalServerError)
+		return
+	}
+	err = reconfigureDNSServer()
+	if err != nil {
+		errorText := fmt.Sprintf("Couldn't reconfigure the DNS server: %s", err)
+		log.Println(errorText)
+		http.Error(w, errorText, http.StatusInternalServerError)
+		return
+	}
+	_, err = fmt.Fprintf(w, "OK %d bootsrap servers\n", len(hosts))
+	if err != nil {
+		errorText := fmt.Sprintf("Couldn't write body: %s", err)
+		log.Println(errorText)
+		http.Error(w, errorText, http.StatusInternalServerError)
+	}
+}
+
 func handleGetVersionJSON(w http.ResponseWriter, r *http.Request) {
 	now := time.Now()
 	if now.Sub(versionCheckLastTime) <= versionCheckPeriod && len(versionCheckJSON) != 0 {
@@ -1317,6 +1356,7 @@ func registerControlHandlers() {
 	http.HandleFunc("/control/querylog_disable", postInstall(optionalAuth(ensurePOST(handleQueryLogDisable))))
 	http.HandleFunc("/control/set_upstream_dns", postInstall(optionalAuth(ensurePOST(handleSetUpstreamDNS))))
 	http.HandleFunc("/control/test_upstream_dns", postInstall(optionalAuth(ensurePOST(handleTestUpstreamDNS))))
+	http.HandleFunc("/control/set_bootstrap_dns", postInstall(optionalAuth(ensurePOST(handleSetBootstrapDNS))))
 	http.HandleFunc("/control/i18n/change_language", postInstall(optionalAuth(ensurePOST(handleI18nChangeLanguage))))
 	http.HandleFunc("/control/i18n/current_language", postInstall(optionalAuth(ensureGET(handleI18nCurrentLanguage))))
 	http.HandleFunc("/control/stats_top", postInstall(optionalAuth(ensureGET(handleStatsTop))))

dns.go

@@ -61,7 +61,7 @@ func generateServerConfig() dnsforward.ServerConfig {
 	for _, u := range config.DNS.UpstreamDNS {
 		opts := upstream.Options{
 			Timeout:   dnsforward.DefaultTimeout,
-			Bootstrap: []string{config.DNS.BootstrapDNS},
+			Bootstrap: config.DNS.BootstrapDNS,
 		}
 		dnsUpstream, err := upstream.AddressToUpstream(u, opts)
 		if err != nil {

dnsforward/dnsforward.go

@@ -66,7 +66,7 @@ type FilteringConfig struct {
 	Ratelimit          int      `yaml:"ratelimit"`
 	RatelimitWhitelist []string `yaml:"ratelimit_whitelist"`
 	RefuseAny          bool     `yaml:"refuse_any"`
-	BootstrapDNS       string   `yaml:"bootstrap_dns"`
+	BootstrapDNS       []string `yaml:"bootstrap_dns"`
 
 	dnsfilter.Config `yaml:",inline"`
 }

openapi/openapi.yaml

@@ -142,6 +142,30 @@ paths:
                             8.8.4.4: OK
                             "192.168.1.104:53535": "Couldn't communicate with DNS server"
 
+    /set_bootstrap_dns:
+        post:
+            tags:
+                - global
+            operationId: setBootstrapDNS
+            summary: 'Set bootstrap DNS for DNS-over-HTTPS and DNS-over-TLS upstreams, empty value will reset it to default values'
+            consumes:
+                - text/plain
+            parameters:
+                -   in: body
+                    name: upstream
+                    description: 'Bootstrap servers, separated by newline or space, port is optional after colon'
+                    schema:
+                        # TODO: use JSON
+                        type: string
+                        example: |
+                            1.1.1.1
+                            1.0.0.1
+                            8.8.8.8 8.8.4.4
+                            192.168.1.104:53535
+            responses:
+                200:
+                    description: OK
+
     /version.json:
         get:
             tags: