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/control_update.go

@@ -0,0 +1,164 @@
+package home
+
+import (
+	"encoding/json"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"syscall"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/update"
+	"github.com/AdguardTeam/AdGuardHome/internal/util"
+	"github.com/AdguardTeam/golibs/log"
+)
+
+type getVersionJSONRequest struct {
+	RecheckNow bool `json:"recheck_now"`
+}
+
+// Get the latest available version from the Internet
+func handleGetVersionJSON(w http.ResponseWriter, r *http.Request) {
+	if Context.disableUpdate {
+		resp := make(map[string]interface{})
+		resp["disabled"] = true
+		d, _ := json.Marshal(resp)
+		_, _ = w.Write(d)
+		return
+	}
+
+	req := getVersionJSONRequest{}
+	var err error
+	if r.ContentLength != 0 {
+		err = json.NewDecoder(r.Body).Decode(&req)
+		if err != nil {
+			httpError(w, http.StatusBadRequest, "JSON parse: %s", err)
+			return
+		}
+	}
+
+	var info update.VersionInfo
+	for i := 0; i != 3; i++ {
+		Context.controlLock.Lock()
+		info, err = Context.updater.GetVersionResponse(req.RecheckNow)
+		Context.controlLock.Unlock()
+		if err != nil && strings.HasSuffix(err.Error(), "i/o timeout") {
+			// This case may happen while we're restarting DNS server
+			// https://github.com/AdguardTeam/AdGuardHome/internal/issues/934
+			continue
+		}
+		break
+	}
+	if err != nil {
+		httpError(w, http.StatusBadGateway, "Couldn't get version check json from %s: %T %s\n", versionCheckURL, err, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_, err = w.Write(getVersionResp(info))
+	if err != nil {
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
+	}
+}
+
+// Perform an update procedure to the latest available version
+func handleUpdate(w http.ResponseWriter, _ *http.Request) {
+	if len(Context.updater.NewVersion) == 0 {
+		httpError(w, http.StatusBadRequest, "/update request isn't allowed now")
+		return
+	}
+
+	err := Context.updater.DoUpdate()
+	if err != nil {
+		httpError(w, http.StatusInternalServerError, "%s", err)
+		return
+	}
+
+	returnOK(w)
+	if f, ok := w.(http.Flusher); ok {
+		f.Flush()
+	}
+
+	go finishUpdate()
+}
+
+// Convert version.json data to our JSON response
+func getVersionResp(info update.VersionInfo) []byte {
+	ret := make(map[string]interface{})
+	ret["can_autoupdate"] = false
+	ret["new_version"] = info.NewVersion
+	ret["announcement"] = info.Announcement
+	ret["announcement_url"] = info.AnnouncementURL
+
+	if info.CanAutoUpdate {
+		canUpdate := true
+
+		tlsConf := tlsConfigSettings{}
+		Context.tls.WriteDiskConfig(&tlsConf)
+
+		if runtime.GOOS != "windows" &&
+			((tlsConf.Enabled && (tlsConf.PortHTTPS < 1024 ||
+				tlsConf.PortDNSOverTLS < 1024 ||
+				tlsConf.PortDNSOverQUIC < 1024)) ||
+				config.BindPort < 1024 ||
+				config.DNS.Port < 1024) {
+			// On UNIX, if we're running under a regular user,
+			//  but with CAP_NET_BIND_SERVICE set on a binary file,
+			//  and we're listening on ports <1024,
+			//  we won't be able to restart after we replace the binary file,
+			//  because we'll lose CAP_NET_BIND_SERVICE capability.
+			canUpdate, _ = util.HaveAdminRights()
+		}
+		ret["can_autoupdate"] = canUpdate
+	}
+
+	d, _ := json.Marshal(ret)
+	return d
+}
+
+// Complete an update procedure
+func finishUpdate() {
+	log.Info("Stopping all tasks")
+	cleanup()
+	cleanupAlways()
+
+	exeName := "AdGuardHome"
+	if runtime.GOOS == "windows" {
+		exeName = "AdGuardHome.exe"
+	}
+	curBinName := filepath.Join(Context.workDir, exeName)
+
+	if runtime.GOOS == "windows" {
+		if Context.runningAsService {
+			// Note:
+			// we can't restart the service via "kardianos/service" package - it kills the process first
+			// we can't start a new instance - Windows doesn't allow it
+			cmd := exec.Command("cmd", "/c", "net stop AdGuardHome & net start AdGuardHome")
+			err := cmd.Start()
+			if err != nil {
+				log.Fatalf("exec.Command() failed: %s", err)
+			}
+			os.Exit(0)
+		}
+
+		cmd := exec.Command(curBinName, os.Args[1:]...)
+		log.Info("Restarting: %v", cmd.Args)
+		cmd.Stdin = os.Stdin
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		err := cmd.Start()
+		if err != nil {
+			log.Fatalf("exec.Command() failed: %s", err)
+		}
+		os.Exit(0)
+	} else {
+		log.Info("Restarting: %v", os.Args)
+		err := syscall.Exec(curBinName, os.Args, os.Environ())
+		if err != nil {
+			log.Fatalf("syscall.Exec() failed: %s", err)
+		}
+		// Unreachable code
+	}
+}