Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/home/web.go

@@ -0,0 +1,209 @@
+package home
+
+import (
+	"context"
+	"crypto/tls"
+	golog "log"
+	"net"
+	"net/http"
+	"strconv"
+	"sync"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/util"
+	"github.com/AdguardTeam/golibs/log"
+	"github.com/NYTimes/gziphandler"
+	"github.com/gobuffalo/packr"
+)
+
+type WebConfig struct {
+	firstRun  bool
+	BindHost  string
+	BindPort  int
+	PortHTTPS int
+}
+
+// HTTPSServer - HTTPS Server
+type HTTPSServer struct {
+	server   *http.Server
+	cond     *sync.Cond
+	condLock sync.Mutex
+	shutdown bool // if TRUE, don't restart the server
+	enabled  bool
+	cert     tls.Certificate
+}
+
+// Web - module object
+type Web struct {
+	conf        *WebConfig
+	forceHTTPS  bool
+	portHTTPS   int
+	httpServer  *http.Server // HTTP module
+	httpsServer HTTPSServer  // HTTPS module
+	errLogger   *golog.Logger
+}
+
+// Proxy between Go's "log" and "golibs/log"
+type logWriter struct {
+}
+
+// HTTP server calls this function to log an error
+func (w *logWriter) Write(p []byte) (int, error) {
+	log.Debug("Web: %s", string(p))
+	return 0, nil
+}
+
+// CreateWeb - create module
+func CreateWeb(conf *WebConfig) *Web {
+	log.Info("Initialize web module")
+
+	w := Web{}
+	w.conf = conf
+
+	lw := logWriter{}
+	w.errLogger = golog.New(&lw, "", 0)
+
+	// Initialize and run the admin Web interface
+	box := packr.NewBox("../../build/static")
+
+	// if not configured, redirect / to /install.html, otherwise redirect /install.html to /
+	http.Handle("/", postInstallHandler(optionalAuthHandler(gziphandler.GzipHandler(http.FileServer(box)))))
+
+	// add handlers for /install paths, we only need them when we're not configured yet
+	if conf.firstRun {
+		log.Info("This is the first launch of AdGuard Home, redirecting everything to /install.html ")
+		http.Handle("/install.html", preInstallHandler(http.FileServer(box)))
+		w.registerInstallHandlers()
+	} else {
+		registerControlHandlers()
+	}
+
+	w.httpsServer.cond = sync.NewCond(&w.httpsServer.condLock)
+	return &w
+}
+
+// WebCheckPortAvailable - check if port is available
+// BUT: if we are already using this port, no need
+func WebCheckPortAvailable(port int) bool {
+	alreadyRunning := false
+	if Context.web.httpsServer.server != nil {
+		alreadyRunning = true
+	}
+	if !alreadyRunning {
+		err := util.CheckPortAvailable(config.BindHost, port)
+		if err != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// TLSConfigChanged - called when TLS configuration has changed
+func (web *Web) TLSConfigChanged(tlsConf tlsConfigSettings) {
+	log.Debug("Web: applying new TLS configuration")
+	web.conf.PortHTTPS = tlsConf.PortHTTPS
+	web.forceHTTPS = (tlsConf.ForceHTTPS && tlsConf.Enabled && tlsConf.PortHTTPS != 0)
+	web.portHTTPS = tlsConf.PortHTTPS
+
+	enabled := tlsConf.Enabled &&
+		tlsConf.PortHTTPS != 0 &&
+		len(tlsConf.PrivateKeyData) != 0 &&
+		len(tlsConf.CertificateChainData) != 0
+	var cert tls.Certificate
+	var err error
+	if enabled {
+		cert, err = tls.X509KeyPair(tlsConf.CertificateChainData, tlsConf.PrivateKeyData)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+
+	web.httpsServer.cond.L.Lock()
+	if web.httpsServer.server != nil {
+		_ = web.httpsServer.server.Shutdown(context.TODO())
+	}
+	web.httpsServer.enabled = enabled
+	web.httpsServer.cert = cert
+	web.httpsServer.cond.Broadcast()
+	web.httpsServer.cond.L.Unlock()
+}
+
+// Start - start serving HTTP requests
+func (web *Web) Start() {
+	// for https, we have a separate goroutine loop
+	go web.tlsServerLoop()
+
+	// this loop is used as an ability to change listening host and/or port
+	for !web.httpsServer.shutdown {
+		printHTTPAddresses("http")
+
+		// we need to have new instance, because after Shutdown() the Server is not usable
+		address := net.JoinHostPort(web.conf.BindHost, strconv.Itoa(web.conf.BindPort))
+		web.httpServer = &http.Server{
+			ErrorLog: web.errLogger,
+			Addr:     address,
+		}
+		err := web.httpServer.ListenAndServe()
+		if err != http.ErrServerClosed {
+			cleanupAlways()
+			log.Fatal(err)
+		}
+		// We use ErrServerClosed as a sign that we need to rebind on new address, so go back to the start of the loop
+	}
+}
+
+// Close - stop HTTP server, possibly waiting for all active connections to be closed
+func (web *Web) Close() {
+	log.Info("Stopping HTTP server...")
+	web.httpsServer.cond.L.Lock()
+	web.httpsServer.shutdown = true
+	web.httpsServer.cond.L.Unlock()
+	if web.httpsServer.server != nil {
+		_ = web.httpsServer.server.Shutdown(context.TODO())
+	}
+	if web.httpServer != nil {
+		_ = web.httpServer.Shutdown(context.TODO())
+	}
+
+	log.Info("Stopped HTTP server")
+}
+
+func (web *Web) tlsServerLoop() {
+	for {
+		web.httpsServer.cond.L.Lock()
+		if web.httpsServer.shutdown {
+			web.httpsServer.cond.L.Unlock()
+			break
+		}
+
+		// this mechanism doesn't let us through until all conditions are met
+		for !web.httpsServer.enabled { // sleep until necessary data is supplied
+			web.httpsServer.cond.Wait()
+			if web.httpsServer.shutdown {
+				web.httpsServer.cond.L.Unlock()
+				return
+			}
+		}
+
+		web.httpsServer.cond.L.Unlock()
+
+		// prepare HTTPS server
+		address := net.JoinHostPort(web.conf.BindHost, strconv.Itoa(web.conf.PortHTTPS))
+		web.httpsServer.server = &http.Server{
+			ErrorLog: web.errLogger,
+			Addr:     address,
+			TLSConfig: &tls.Config{
+				Certificates: []tls.Certificate{web.httpsServer.cert},
+				MinVersion:   tls.VersionTLS12,
+				RootCAs:      Context.tlsRoots,
+				CipherSuites: Context.tlsCiphers,
+			},
+		}
+
+		printHTTPAddresses("https")
+		err := web.httpsServer.server.ListenAndServeTLS("", "")
+		if err != http.ErrServerClosed {
+			cleanupAlways()
+			log.Fatal(err)
+		}
+	}
+}