Merge: - install: recover from error on DNS server start

Close #1293

Squashed commit of the following:

commit 0981754c5c2c67f2567ee4af0d9ab24377c53413
Merge: ef81f2c8 a6d75118
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Jan 16 14:19:20 2020 +0300

    Merge remote-tracking branch 'origin/master' into 1293-install

commit ef81f2c886f3bfcff4e4352d7ecea6642be7d8e1
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 30 18:32:11 2019 +0300

    linter

commit 9e205be53d9de25bd2ad63398644e14b09f95238
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Dec 30 17:22:17 2019 +0300

    - install: recover from error on DNS server start

    Close all modules properly
    Don't register HTTP handlers twice

dnsfilter/dnsfilter.go

@@ -577,6 +577,10 @@ func New(c *Config, filters map[int]string) *Dnsfilter {
 		}
 	}
 
+	return d
+}
+
+func (d *Dnsfilter) Start() {
 	d.filtersInitializerChan = make(chan filtersInitializerParams, 1)
 	go d.filtersInitializer()
 
@@ -584,7 +588,6 @@ func New(c *Config, filters map[int]string) *Dnsfilter {
 		d.registerSecurityHandlers()
 		d.registerRewritesHandlers()
 	}
-	return d
 }
 
 //

dnsforward/dnsforward.go

@@ -33,6 +33,8 @@ var defaultDNS = []string{
 }
 var defaultBootstrap = []string{"9.9.9.9", "149.112.112.112"}
 
+var webRegistered bool
+
 // Server is the main way to start a DNS server.
 //
 // Example:
@@ -54,8 +56,7 @@ type Server struct {
 	// We don't Start() it and so no listen port is required.
 	internalProxy *proxy.Proxy
 
-	webRegistered bool
-	isRunning     bool
+	isRunning bool
 
 	sync.RWMutex
 	conf ServerConfig
@@ -318,8 +319,8 @@ func (s *Server) Prepare(config *ServerConfig) error {
 		log.Fatal("len(proxyConfig.Upstreams) == 0")
 	}
 
-	if !s.webRegistered && s.conf.HTTPRegister != nil {
-		s.webRegistered = true
+	if !webRegistered && s.conf.HTTPRegister != nil {
+		webRegistered = true
 		s.registerHandlers()
 	}
 

home/control_install.go

@@ -244,6 +244,9 @@ func handleInstallConfigure(w http.ResponseWriter, r *http.Request) {
 	var err2 error
 	if err == nil {
 		err2 = startDNSServer()
+		if err2 != nil {
+			closeDNSServer()
+		}
 	}
 	if err != nil || err2 != nil {
 		config.firstRun = true

home/dns.go

@@ -66,12 +66,14 @@ func initDNSServer() error {
 	dnsConfig := generateServerConfig()
 	err = Context.dnsServer.Prepare(&dnsConfig)
 	if err != nil {
+		closeDNSServer()
 		return fmt.Errorf("dnsServer.Prepare: %s", err)
 	}
 
 	sessFilename := filepath.Join(baseDir, "sessions.db")
 	config.auth = InitAuth(sessFilename, config.Users, config.WebSessionTTLHours*60*60)
 	if config.auth == nil {
+		closeDNSServer()
 		return fmt.Errorf("Couldn't initialize Auth module")
 	}
 	config.Users = nil
@@ -224,7 +226,10 @@ func startDNSServer() error {
 		return errorx.Decorate(err, "Couldn't start forwarding DNS server")
 	}
 
+	Context.dnsFilter.Start()
 	startFiltering()
+	Context.stats.Start()
+	Context.queryLog.Start()
 
 	const topClientsNumber = 100 // the number of clients to get
 	topClients := Context.stats.GetTopClientsIP(topClientsNumber)
@@ -261,19 +266,36 @@ func stopDNSServer() error {
 		return errorx.Decorate(err, "Couldn't stop forwarding DNS server")
 	}
 
-	// DNS forward module must be closed BEFORE stats or queryLog because it depends on them
-	Context.dnsServer.Close()
-
-	Context.dnsFilter.Close()
-	Context.dnsFilter = nil
-
-	Context.stats.Close()
-	Context.stats = nil
-
-	Context.queryLog.Close()
-	Context.queryLog = nil
-
-	config.auth.Close()
-	config.auth = nil
+	closeDNSServer()
 	return nil
 }
+
+func closeDNSServer() {
+	// DNS forward module must be closed BEFORE stats or queryLog because it depends on them
+	if Context.dnsServer != nil {
+		Context.dnsServer.Close()
+		Context.dnsServer = nil
+	}
+
+	if Context.dnsFilter != nil {
+		Context.dnsFilter.Close()
+		Context.dnsFilter = nil
+	}
+
+	if Context.stats != nil {
+		Context.stats.Close()
+		Context.stats = nil
+	}
+
+	if Context.queryLog != nil {
+		Context.queryLog.Close()
+		Context.queryLog = nil
+	}
+
+	if config.auth != nil {
+		config.auth.Close()
+		config.auth = nil
+	}
+
+	log.Debug("Closed all DNS modules")
+}

querylog/qlog.go

@@ -44,11 +44,14 @@ func newQueryLog(conf Config) *queryLog {
 	if !checkInterval(l.conf.Interval) {
 		l.conf.Interval = 1
 	}
+	return &l
+}
+
+func (l *queryLog) Start() {
 	if l.conf.HTTPRegister != nil {
 		l.initWeb()
 	}
 	go l.periodicRotate()
-	return &l
 }
 
 func (l *queryLog) Close() {

querylog/querylog.go

@@ -18,6 +18,8 @@ type DiskConfig struct {
 
 // QueryLog - main interface
 type QueryLog interface {
+	Start()
+
 	// Close query log object
 	Close()
 

stats/stats.go

@@ -36,6 +36,8 @@ func New(conf Config) (Stats, error) {
 
 // Stats - main interface
 type Stats interface {
+	Start()
+
 	// Close object.
 	// This function is not thread safe
 	//  (can't be called in parallel with any other function of this interface).

stats/stats_unit.go

@@ -114,14 +114,15 @@ func createObject(conf Config) (*statsCtx, error) {
 	}
 	s.unit = &u
 
-	s.initWeb()
-
-	go s.periodicFlush()
-
 	log.Debug("Stats: initialized")
 	return &s, nil
 }
 
+func (s *statsCtx) Start() {
+	s.initWeb()
+	go s.periodicFlush()
+}
+
 func checkInterval(days uint32) bool {
 	return days == 1 || days == 7 || days == 30 || days == 90
 }