syncthing/cmd/syncthing/gui.go

// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.

package main

import (
	"bytes"
	"compress/gzip"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"mime"
	"net"
	"net/http"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/rcrowley/go-metrics"
	"github.com/syncthing/syncthing/lib/auto"
	"github.com/syncthing/syncthing/lib/config"
	"github.com/syncthing/syncthing/lib/db"
	"github.com/syncthing/syncthing/lib/discover"
	"github.com/syncthing/syncthing/lib/events"
	"github.com/syncthing/syncthing/lib/logger"
	"github.com/syncthing/syncthing/lib/model"
	"github.com/syncthing/syncthing/lib/osutil"
	"github.com/syncthing/syncthing/lib/protocol"
	"github.com/syncthing/syncthing/lib/rand"
	"github.com/syncthing/syncthing/lib/stats"
	"github.com/syncthing/syncthing/lib/sync"
	"github.com/syncthing/syncthing/lib/tlsutil"
	"github.com/syncthing/syncthing/lib/upgrade"
	"github.com/vitrun/qart/qr"
	"golang.org/x/crypto/bcrypt"
)

var (
	configInSync = true
	startTime    = time.Now()
)

type apiService struct {
	id                 protocol.DeviceID
	cfg                configIntf
	httpsCertFile      string
	httpsKeyFile       string
	assetDir           string
	themes             []string
	model              modelIntf
	eventSub           events.BufferedSubscription
	discoverer         discover.CachingMux
	connectionsService connectionsIntf
	fss                *folderSummaryService
	systemConfigMut    sync.Mutex    // serializes posts to /rest/system/config
	stop               chan struct{} // signals intentional stop
	configChanged      chan struct{} // signals intentional listener close due to config change
	started            chan struct{} // signals startup complete, for testing only

	listener    net.Listener
	listenerMut sync.Mutex

	guiErrors logger.Recorder
	systemLog logger.Recorder
}

type modelIntf interface {
	GlobalDirectoryTree(folder, prefix string, levels int, dirsonly bool) map[string]interface{}
	Completion(device protocol.DeviceID, folder string) float64
	Override(folder string)
	NeedFolderFiles(folder string, page, perpage int) ([]db.FileInfoTruncated, []db.FileInfoTruncated, []db.FileInfoTruncated, int)
	NeedSize(folder string) (nfiles int, bytes int64)
	ConnectionStats() map[string]interface{}
	DeviceStatistics() map[string]stats.DeviceStatistics
	FolderStatistics() map[string]stats.FolderStatistics
	CurrentFolderFile(folder string, file string) (protocol.FileInfo, bool)
	CurrentGlobalFile(folder string, file string) (protocol.FileInfo, bool)
	ResetFolder(folder string)
	Availability(folder, file string, version protocol.Vector, block protocol.BlockInfo) []model.Availability
	GetIgnores(folder string) ([]string, []string, error)
	SetIgnores(folder string, content []string) error
	PauseDevice(device protocol.DeviceID)
	ResumeDevice(device protocol.DeviceID)
	DelayScan(folder string, next time.Duration)
	ScanFolder(folder string) error
	ScanFolders() map[string]error
	ScanFolderSubs(folder string, subs []string) error
	BringToFront(folder, file string)
	ConnectedTo(deviceID protocol.DeviceID) bool
	GlobalSize(folder string) (nfiles, deleted int, bytes int64)
	LocalSize(folder string) (nfiles, deleted int, bytes int64)
	CurrentLocalVersion(folder string) (int64, bool)
	RemoteLocalVersion(folder string) (int64, bool)
	State(folder string) (string, time.Time, error)
}

type configIntf interface {
	GUI() config.GUIConfiguration
	Raw() config.Configuration
	Options() config.OptionsConfiguration
	Replace(cfg config.Configuration) config.CommitResponse
	Subscribe(c config.Committer)
	Folders() map[string]config.FolderConfiguration
	Devices() map[protocol.DeviceID]config.DeviceConfiguration
	Save() error
	ListenAddresses() []string
}

type connectionsIntf interface {
	Status() map[string]interface{}
}

func newAPIService(id protocol.DeviceID, cfg configIntf, httpsCertFile, httpsKeyFile, assetDir string, m modelIntf, eventSub events.BufferedSubscription, discoverer discover.CachingMux, connectionsService connectionsIntf, errors, systemLog logger.Recorder) (*apiService, error) {
	service := &apiService{
		id:                 id,
		cfg:                cfg,
		httpsCertFile:      httpsCertFile,
		httpsKeyFile:       httpsKeyFile,
		assetDir:           assetDir,
		model:              m,
		eventSub:           eventSub,
		discoverer:         discoverer,
		connectionsService: connectionsService,
		systemConfigMut:    sync.NewMutex(),
		stop:               make(chan struct{}),
		configChanged:      make(chan struct{}),
		listenerMut:        sync.NewMutex(),
		guiErrors:          errors,
		systemLog:          systemLog,
	}

	seen := make(map[string]struct{})
	// Load themes from compiled in assets.
	for file := range auto.Assets() {
		theme := strings.Split(file, "/")[0]
		if _, ok := seen[theme]; !ok {
			seen[theme] = struct{}{}
			service.themes = append(service.themes, theme)
		}
	}
	if assetDir != "" {
		// Load any extra themes from the asset override dir.
		for _, dir := range dirNames(assetDir) {
			if _, ok := seen[dir]; !ok {
				seen[dir] = struct{}{}
				service.themes = append(service.themes, dir)
			}
		}
	}

	var err error
	service.listener, err = service.getListener(cfg.GUI())
	return service, err
}

func (s *apiService) getListener(guiCfg config.GUIConfiguration) (net.Listener, error) {
	cert, err := tls.LoadX509KeyPair(s.httpsCertFile, s.httpsKeyFile)
	if err != nil {
		l.Infoln("Loading HTTPS certificate:", err)
		l.Infoln("Creating new HTTPS certificate")

		// When generating the HTTPS certificate, use the system host name per
		// default. If that isn't available, use the "syncthing" default.
		var name string
		name, err = os.Hostname()
		if err != nil {
			name = tlsDefaultCommonName
		}

		cert, err = tlsutil.NewCertificate(s.httpsCertFile, s.httpsKeyFile, name, httpsRSABits)
	}
	if err != nil {
		return nil, err
	}
	tlsCfg := &tls.Config{
		Certificates: []tls.Certificate{cert},
		MinVersion:   tls.VersionTLS10, // No SSLv3
		CipherSuites: []uint16{
			// No RC4
			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
			tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
			tls.TLS_RSA_WITH_AES_128_CBC_SHA,
			tls.TLS_RSA_WITH_AES_256_CBC_SHA,
			tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
			tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
		},
	}

	rawListener, err := net.Listen("tcp", guiCfg.Address())
	if err != nil {
		return nil, err
	}

	listener := &tlsutil.DowngradingListener{
		Listener:  rawListener,
		TLSConfig: tlsCfg,
	}
	return listener, nil
}

func sendJSON(w http.ResponseWriter, jsonObject interface{}) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	// Marshalling might fail, in which case we should return a 500 with the
	// actual error.
	bs, err := json.Marshal(jsonObject)
	if err != nil {
		// This Marshal() can't fail though.
		bs, _ = json.Marshal(map[string]string{"error": err.Error()})
		http.Error(w, string(bs), http.StatusInternalServerError)
		return
	}
	w.Write(bs)
}

func (s *apiService) Serve() {
	s.listenerMut.Lock()
	listener := s.listener
	s.listenerMut.Unlock()

	if listener == nil {
		// Not much we can do here other than exit quickly. The supervisor
		// will log an error at some point.
		return
	}

	// The GET handlers
	getRestMux := http.NewServeMux()
	getRestMux.HandleFunc("/rest/db/completion", s.getDBCompletion)              // device folder
	getRestMux.HandleFunc("/rest/db/file", s.getDBFile)                          // folder file
	getRestMux.HandleFunc("/rest/db/ignores", s.getDBIgnores)                    // folder
	getRestMux.HandleFunc("/rest/db/need", s.getDBNeed)                          // folder [perpage] [page]
	getRestMux.HandleFunc("/rest/db/status", s.getDBStatus)                      // folder
	getRestMux.HandleFunc("/rest/db/browse", s.getDBBrowse)                      // folder [prefix] [dirsonly] [levels]
	getRestMux.HandleFunc("/rest/events", s.getEvents)                           // since [limit]
	getRestMux.HandleFunc("/rest/stats/device", s.getDeviceStats)                // -
	getRestMux.HandleFunc("/rest/stats/folder", s.getFolderStats)                // -
	getRestMux.HandleFunc("/rest/svc/deviceid", s.getDeviceID)                   // id
	getRestMux.HandleFunc("/rest/svc/lang", s.getLang)                           // -
	getRestMux.HandleFunc("/rest/svc/report", s.getReport)                       // -
	getRestMux.HandleFunc("/rest/system/browse", s.getSystemBrowse)              // current
	getRestMux.HandleFunc("/rest/system/config", s.getSystemConfig)              // -
	getRestMux.HandleFunc("/rest/system/config/insync", s.getSystemConfigInsync) // -
	getRestMux.HandleFunc("/rest/system/connections", s.getSystemConnections)    // -
	getRestMux.HandleFunc("/rest/system/discovery", s.getSystemDiscovery)        // -
	getRestMux.HandleFunc("/rest/system/error", s.getSystemError)                // -
	getRestMux.HandleFunc("/rest/system/ping", s.restPing)                       // -
	getRestMux.HandleFunc("/rest/system/status", s.getSystemStatus)              // -
	getRestMux.HandleFunc("/rest/system/upgrade", s.getSystemUpgrade)            // -
	getRestMux.HandleFunc("/rest/system/version", s.getSystemVersion)            // -
	getRestMux.HandleFunc("/rest/system/debug", s.getSystemDebug)                // -
	getRestMux.HandleFunc("/rest/system/log", s.getSystemLog)                    // [since]
	getRestMux.HandleFunc("/rest/system/log.txt", s.getSystemLogTxt)             // [since]

	// The POST handlers
	postRestMux := http.NewServeMux()
	postRestMux.HandleFunc("/rest/db/prio", s.postDBPrio)                      // folder file [perpage] [page]
	postRestMux.HandleFunc("/rest/db/ignores", s.postDBIgnores)                // folder
	postRestMux.HandleFunc("/rest/db/override", s.postDBOverride)              // folder
	postRestMux.HandleFunc("/rest/db/scan", s.postDBScan)                      // folder [sub...] [delay]
	postRestMux.HandleFunc("/rest/system/config", s.postSystemConfig)          // <body>
	postRestMux.HandleFunc("/rest/system/error", s.postSystemError)            // <body>
	postRestMux.HandleFunc("/rest/system/error/clear", s.postSystemErrorClear) // -
	postRestMux.HandleFunc("/rest/system/ping", s.restPing)                    // -
	postRestMux.HandleFunc("/rest/system/reset", s.postSystemReset)            // [folder]
	postRestMux.HandleFunc("/rest/system/restart", s.postSystemRestart)        // -
	postRestMux.HandleFunc("/rest/system/shutdown", s.postSystemShutdown)      // -
	postRestMux.HandleFunc("/rest/system/upgrade", s.postSystemUpgrade)        // -
	postRestMux.HandleFunc("/rest/system/pause", s.postSystemPause)            // device
	postRestMux.HandleFunc("/rest/system/resume", s.postSystemResume)          // device
	postRestMux.HandleFunc("/rest/system/debug", s.postSystemDebug)            // [enable] [disable]

	// Debug endpoints, not for general use
	getRestMux.HandleFunc("/rest/debug/peerCompletion", s.getPeerCompletion)
	getRestMux.HandleFunc("/rest/debug/httpmetrics", s.getSystemHTTPMetrics)

	// A handler that splits requests between the two above and disables
	// caching
	restMux := noCacheMiddleware(metricsMiddleware(getPostHandler(getRestMux, postRestMux)))

	// The main routing handler
	mux := http.NewServeMux()
	mux.Handle("/rest/", restMux)
	mux.HandleFunc("/qr/", s.getQR)

	// Serve compiled in assets unless an asset directory was set (for development)
	assets := &embeddedStatic{
		theme:        s.cfg.GUI().Theme,
		lastModified: time.Now().Truncate(time.Second), // must truncate, for the wire precision is 1s
		mut:          sync.NewRWMutex(),
		assetDir:     s.assetDir,
		assets:       auto.Assets(),
	}
	mux.Handle("/", assets)

	// Handle the special meta.js path
	mux.HandleFunc("/meta.js", s.getJSMetadata)

	s.cfg.Subscribe(assets)

	guiCfg := s.cfg.GUI()

	// Wrap everything in CSRF protection. The /rest prefix should be
	// protected, other requests will grant cookies.
	handler := csrfMiddleware(s.id.String()[:5], "/rest", guiCfg, mux)

	// Add our version and ID as a header to responses
	handler = withDetailsMiddleware(s.id, handler)

	// Wrap everything in basic auth, if user/password is set.
	if len(guiCfg.User) > 0 && len(guiCfg.Password) > 0 {
		handler = basicAuthAndSessionMiddleware("sessionid-"+s.id.String()[:5], guiCfg, handler)
	}

	// Redirect to HTTPS if we are supposed to
	if guiCfg.UseTLS() {
		handler = redirectToHTTPSMiddleware(handler)
	}

	// Add the CORS handling
	handler = corsMiddleware(handler)

	handler = debugMiddleware(handler)

	srv := http.Server{
		Handler:     handler,
		ReadTimeout: 10 * time.Second,
	}

	s.fss = newFolderSummaryService(s.cfg, s.model)
	defer s.fss.Stop()
	s.fss.ServeBackground()

	l.Infoln("GUI and API listening on", listener.Addr())
	l.Infoln("Access the GUI via the following URL:", guiCfg.URL())
	if s.started != nil {
		// only set when run by the tests
		close(s.started)
	}
	err := srv.Serve(listener)

	// The return could be due to an intentional close. Wait for the stop
	// signal before returning. IF there is no stop signal within a second, we
	// assume it was unintentional and log the error before retrying.
	select {
	case <-s.stop:
	case <-s.configChanged:
	case <-time.After(time.Second):
		l.Warnln("API:", err)
	}
}

func (s *apiService) Stop() {
	s.listenerMut.Lock()
	listener := s.listener
	s.listenerMut.Unlock()

	close(s.stop)

	// listener may be nil here if we've had a config change to a broken
	// configuration, in which case we shouldn't try to close it.
	if listener != nil {
		listener.Close()
	}
}

func (s *apiService) String() string {
	return fmt.Sprintf("apiService@%p", s)
}

func (s *apiService) VerifyConfiguration(from, to config.Configuration) error {
	return nil
}

func (s *apiService) CommitConfiguration(from, to config.Configuration) bool {
	if to.GUI == from.GUI {
		return true
	}

	// Order here is important. We must close the listener to stop Serve(). We
	// must create a new listener before Serve() starts again. We can't create
	// a new listener on the same port before the previous listener is closed.
	// To assist in this little dance the Serve() method will wait for a
	// signal on the configChanged channel after the listener has closed.

	s.listenerMut.Lock()
	defer s.listenerMut.Unlock()

	s.listener.Close()

	var err error
	s.listener, err = s.getListener(to.GUI)
	if err != nil {
		// Ideally this should be a verification error, but we check it by
		// creating a new listener which requires shutting down the previous
		// one first, which is too destructive for the VerifyConfiguration
		// method.
		return false
	}

	s.configChanged <- struct{}{}

	return true
}

func getPostHandler(get, post http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		switch r.Method {
		case "GET":
			get.ServeHTTP(w, r)
		case "POST":
			post.ServeHTTP(w, r)
		default:
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		}
	})
}

func debugMiddleware(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		t0 := time.Now()
		h.ServeHTTP(w, r)

		if shouldDebugHTTP() {
			ms := 1000 * time.Since(t0).Seconds()

			// The variable `w` is most likely a *http.response, which we can't do
			// much with since it's a non exported type. We can however peek into
			// it with reflection to get at the status code and number of bytes
			// written.
			var status, written int64
			if rw := reflect.Indirect(reflect.ValueOf(w)); rw.IsValid() && rw.Kind() == reflect.Struct {
				if rf := rw.FieldByName("status"); rf.IsValid() && rf.Kind() == reflect.Int {
					status = rf.Int()
				}
				if rf := rw.FieldByName("written"); rf.IsValid() && rf.Kind() == reflect.Int64 {
					written = rf.Int()
				}
			}
			httpl.Debugf("http: %s %q: status %d, %d bytes in %.02f ms", r.Method, r.URL.String(), status, written, ms)
		}
	})
}

func corsMiddleware(next http.Handler) http.Handler {
	// Handle CORS headers and CORS OPTIONS request.
	// CORS OPTIONS request are typically sent by browser during AJAX preflight
	// when the browser initiate a POST request.
	//
	// As the OPTIONS request is unauthorized, this handler must be the first
	// of the chain (hence added at the end).
	//
	// See https://www.w3.org/TR/cors/ for details.
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Process OPTIONS requests
		if r.Method == "OPTIONS" {
			// Only GET/POST Methods are supported
			w.Header().Set("Access-Control-Allow-Methods", "GET, POST")
			// Only this custom header can be set
			w.Header().Set("Access-Control-Allow-Headers", "X-API-Key")
			// The request is meant to be cached 10 minutes
			w.Header().Set("Access-Control-Max-Age", "600")

			// Indicate that no content will be returned
			w.WriteHeader(204)

			return
		}

		// For everything else, pass to the next handler
		next.ServeHTTP(w, r)
		return
	})
}

func metricsMiddleware(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		t := metrics.GetOrRegisterTimer(r.URL.Path, nil)
		t0 := time.Now()
		h.ServeHTTP(w, r)
		t.UpdateSince(t0)
	})
}

func redirectToHTTPSMiddleware(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.TLS == nil {
			// Redirect HTTP requests to HTTPS
			r.URL.Host = r.Host
			r.URL.Scheme = "https"
			http.Redirect(w, r, r.URL.String(), http.StatusTemporaryRedirect)
		} else {
			h.ServeHTTP(w, r)
		}
	})
}

func noCacheMiddleware(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Cache-Control", "max-age=0, no-cache, no-store")
		w.Header().Set("Expires", time.Now().UTC().Format(http.TimeFormat))
		w.Header().Set("Pragma", "no-cache")
		h.ServeHTTP(w, r)
	})
}

func withDetailsMiddleware(id protocol.DeviceID, h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-Syncthing-Version", Version)
		w.Header().Set("X-Syncthing-ID", id.String())
		h.ServeHTTP(w, r)
	})
}

func (s *apiService) restPing(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, map[string]string{"ping": "pong"})
}

func (s *apiService) getJSMetadata(w http.ResponseWriter, r *http.Request) {
	meta, _ := json.Marshal(map[string]string{
		"deviceID": s.id.String(),
	})
	w.Header().Set("Content-Type", "application/javascript")
	fmt.Fprintf(w, "var metadata = %s;\n", meta)
}

func (s *apiService) getSystemVersion(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, map[string]string{
		"version":     Version,
		"codename":    Codename,
		"longVersion": LongVersion,
		"os":          runtime.GOOS,
		"arch":        runtime.GOARCH,
	})
}

func (s *apiService) getSystemDebug(w http.ResponseWriter, r *http.Request) {
	names := l.Facilities()
	enabled := l.FacilityDebugging()
	sort.Strings(enabled)
	sendJSON(w, map[string]interface{}{
		"facilities": names,
		"enabled":    enabled,
	})
}

func (s *apiService) postSystemDebug(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	q := r.URL.Query()
	for _, f := range strings.Split(q.Get("enable"), ",") {
		if f == "" || l.ShouldDebug(f) {
			continue
		}
		l.SetDebug(f, true)
		l.Infof("Enabled debug data for %q", f)
	}
	for _, f := range strings.Split(q.Get("disable"), ",") {
		if f == "" || !l.ShouldDebug(f) {
			continue
		}
		l.SetDebug(f, false)
		l.Infof("Disabled debug data for %q", f)
	}
}

func (s *apiService) getDBBrowse(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	folder := qs.Get("folder")
	prefix := qs.Get("prefix")
	dirsonly := qs.Get("dirsonly") != ""

	levels, err := strconv.Atoi(qs.Get("levels"))
	if err != nil {
		levels = -1
	}

	sendJSON(w, s.model.GlobalDirectoryTree(folder, prefix, levels, dirsonly))
}

func (s *apiService) getDBCompletion(w http.ResponseWriter, r *http.Request) {
	var qs = r.URL.Query()
	var folder = qs.Get("folder")
	var deviceStr = qs.Get("device")

	device, err := protocol.DeviceIDFromString(deviceStr)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	sendJSON(w, map[string]float64{
		"completion": s.model.Completion(device, folder),
	})
}

func (s *apiService) getDBStatus(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	folder := qs.Get("folder")
	sendJSON(w, folderSummary(s.cfg, s.model, folder))
}

func folderSummary(cfg configIntf, m modelIntf, folder string) map[string]interface{} {
	var res = make(map[string]interface{})

	res["invalid"] = cfg.Folders()[folder].Invalid

	globalFiles, globalDeleted, globalBytes := m.GlobalSize(folder)
	res["globalFiles"], res["globalDeleted"], res["globalBytes"] = globalFiles, globalDeleted, globalBytes

	localFiles, localDeleted, localBytes := m.LocalSize(folder)
	res["localFiles"], res["localDeleted"], res["localBytes"] = localFiles, localDeleted, localBytes

	needFiles, needBytes := m.NeedSize(folder)
	res["needFiles"], res["needBytes"] = needFiles, needBytes

	res["inSyncFiles"], res["inSyncBytes"] = globalFiles-needFiles, globalBytes-needBytes

	var err error
	res["state"], res["stateChanged"], err = m.State(folder)
	if err != nil {
		res["error"] = err.Error()
	}

	lv, _ := m.CurrentLocalVersion(folder)
	rv, _ := m.RemoteLocalVersion(folder)

	res["version"] = lv + rv

	ignorePatterns, _, _ := m.GetIgnores(folder)
	res["ignorePatterns"] = false
	for _, line := range ignorePatterns {
		if len(line) > 0 && !strings.HasPrefix(line, "//") {
			res["ignorePatterns"] = true
			break
		}
	}

	return res
}

func (s *apiService) postDBOverride(w http.ResponseWriter, r *http.Request) {
	var qs = r.URL.Query()
	var folder = qs.Get("folder")
	go s.model.Override(folder)
}

func (s *apiService) getDBNeed(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()

	folder := qs.Get("folder")

	page, err := strconv.Atoi(qs.Get("page"))
	if err != nil || page < 1 {
		page = 1
	}
	perpage, err := strconv.Atoi(qs.Get("perpage"))
	if err != nil || perpage < 1 {
		perpage = 1 << 16
	}

	progress, queued, rest, total := s.model.NeedFolderFiles(folder, page, perpage)

	// Convert the struct to a more loose structure, and inject the size.
	sendJSON(w, map[string]interface{}{
		"progress": s.toNeedSlice(progress),
		"queued":   s.toNeedSlice(queued),
		"rest":     s.toNeedSlice(rest),
		"total":    total,
		"page":     page,
		"perpage":  perpage,
	})
}

func (s *apiService) getSystemConnections(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, s.model.ConnectionStats())
}

func (s *apiService) getDeviceStats(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, s.model.DeviceStatistics())
}

func (s *apiService) getFolderStats(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, s.model.FolderStatistics())
}

func (s *apiService) getDBFile(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	folder := qs.Get("folder")
	file := qs.Get("file")
	gf, gfOk := s.model.CurrentGlobalFile(folder, file)
	lf, lfOk := s.model.CurrentFolderFile(folder, file)

	if !(gfOk || lfOk) {
		// This file for sure does not exist.
		http.Error(w, "No such object in the index", http.StatusNotFound)
		return
	}

	av := s.model.Availability(folder, file, protocol.Vector{}, protocol.BlockInfo{})
	sendJSON(w, map[string]interface{}{
		"global":       jsonFileInfo(gf),
		"local":        jsonFileInfo(lf),
		"availability": av,
	})
}

func (s *apiService) getSystemConfig(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, s.cfg.Raw())
}

func (s *apiService) postSystemConfig(w http.ResponseWriter, r *http.Request) {
	s.systemConfigMut.Lock()
	defer s.systemConfigMut.Unlock()

	to, err := config.ReadJSON(r.Body, myID)
	r.Body.Close()
	if err != nil {
		l.Warnln("decoding posted config:", err)
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if to.GUI.Password != s.cfg.GUI().Password {
		if to.GUI.Password != "" {
			hash, err := bcrypt.GenerateFromPassword([]byte(to.GUI.Password), 0)
			if err != nil {
				l.Warnln("bcrypting password:", err)
				http.Error(w, err.Error(), http.StatusInternalServerError)
				return
			}

			to.GUI.Password = string(hash)
		}
	}

	// Fixup usage reporting settings

	if curAcc := s.cfg.Options().URAccepted; to.Options.URAccepted > curAcc {
		// UR was enabled
		to.Options.URAccepted = usageReportVersion
		to.Options.URUniqueID = rand.String(8)
	} else if to.Options.URAccepted < curAcc {
		// UR was disabled
		to.Options.URAccepted = -1
		to.Options.URUniqueID = ""
	}

	// Activate and save

	resp := s.cfg.Replace(to)
	configInSync = !resp.RequiresRestart
	s.cfg.Save()
}

func (s *apiService) getSystemConfigInsync(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, map[string]bool{"configInSync": configInSync})
}

func (s *apiService) postSystemRestart(w http.ResponseWriter, r *http.Request) {
	s.flushResponse(`{"ok": "restarting"}`, w)
	go restart()
}

func (s *apiService) postSystemReset(w http.ResponseWriter, r *http.Request) {
	var qs = r.URL.Query()
	folder := qs.Get("folder")

	if len(folder) > 0 {
		if _, ok := s.cfg.Folders()[folder]; !ok {
			http.Error(w, "Invalid folder ID", 500)
			return
		}
	}

	if len(folder) == 0 {
		// Reset all folders.
		for folder := range s.cfg.Folders() {
			s.model.ResetFolder(folder)
		}
		s.flushResponse(`{"ok": "resetting database"}`, w)
	} else {
		// Reset a specific folder, assuming it's supposed to exist.
		s.model.ResetFolder(folder)
		s.flushResponse(`{"ok": "resetting folder `+folder+`"}`, w)
	}

	go restart()
}

func (s *apiService) postSystemShutdown(w http.ResponseWriter, r *http.Request) {
	s.flushResponse(`{"ok": "shutting down"}`, w)
	go shutdown()
}

func (s *apiService) flushResponse(resp string, w http.ResponseWriter) {
	w.Write([]byte(resp + "\n"))
	f := w.(http.Flusher)
	f.Flush()
}

var cpuUsagePercent [10]float64 // The last ten seconds
var cpuUsageLock = sync.NewRWMutex()

func (s *apiService) getSystemStatus(w http.ResponseWriter, r *http.Request) {
	var m runtime.MemStats
	runtime.ReadMemStats(&m)

	tilde, _ := osutil.ExpandTilde("~")
	res := make(map[string]interface{})
	res["myID"] = myID.String()
	res["goroutines"] = runtime.NumGoroutine()
	res["alloc"] = m.Alloc
	res["sys"] = m.Sys - m.HeapReleased
	res["tilde"] = tilde
	if s.cfg.Options().LocalAnnEnabled || s.cfg.Options().GlobalAnnEnabled {
		res["discoveryEnabled"] = true
		discoErrors := make(map[string]string)
		discoMethods := 0
		for disco, err := range s.discoverer.ChildErrors() {
			discoMethods++
			if err != nil {
				discoErrors[disco] = err.Error()
			}
		}
		res["discoveryMethods"] = discoMethods
		res["discoveryErrors"] = discoErrors
	}

	res["connectionServiceStatus"] = s.connectionsService.Status()

	cpuUsageLock.RLock()
	var cpusum float64
	for _, p := range cpuUsagePercent {
		cpusum += p
	}
	cpuUsageLock.RUnlock()
	res["cpuPercent"] = cpusum / float64(len(cpuUsagePercent)) / float64(runtime.NumCPU())
	res["pathSeparator"] = string(filepath.Separator)
	res["uptime"] = int(time.Since(startTime).Seconds())
	res["startTime"] = startTime
	res["themes"] = s.themes

	sendJSON(w, res)
}

func (s *apiService) getSystemError(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, map[string][]logger.Line{
		"errors": s.guiErrors.Since(time.Time{}),
	})
}

func (s *apiService) postSystemError(w http.ResponseWriter, r *http.Request) {
	bs, _ := ioutil.ReadAll(r.Body)
	r.Body.Close()
	l.Warnln(string(bs))
}

func (s *apiService) postSystemErrorClear(w http.ResponseWriter, r *http.Request) {
	s.guiErrors.Clear()
}

func (s *apiService) getSystemLog(w http.ResponseWriter, r *http.Request) {
	q := r.URL.Query()
	since, err := time.Parse(time.RFC3339, q.Get("since"))
	l.Debugln(err)
	sendJSON(w, map[string][]logger.Line{
		"messages": s.systemLog.Since(since),
	})
}

func (s *apiService) getSystemLogTxt(w http.ResponseWriter, r *http.Request) {
	q := r.URL.Query()
	since, err := time.Parse(time.RFC3339, q.Get("since"))
	l.Debugln(err)
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")

	for _, line := range s.systemLog.Since(since) {
		fmt.Fprintf(w, "%s: %s\n", line.When.Format(time.RFC3339), line.Message)
	}
}

func (s *apiService) getSystemHTTPMetrics(w http.ResponseWriter, r *http.Request) {
	stats := make(map[string]interface{})
	metrics.Each(func(name string, intf interface{}) {
		if m, ok := intf.(*metrics.StandardTimer); ok {
			pct := m.Percentiles([]float64{0.50, 0.95, 0.99})
			for i := range pct {
				pct[i] /= 1e6 // ns to ms
			}
			stats[name] = map[string]interface{}{
				"count":         m.Count(),
				"sumMs":         m.Sum() / 1e6, // ns to ms
				"ratesPerS":     []float64{m.Rate1(), m.Rate5(), m.Rate15()},
				"percentilesMs": pct,
			}
		}
	})
	bs, _ := json.MarshalIndent(stats, "", "  ")
	w.Write(bs)
}

func (s *apiService) getSystemDiscovery(w http.ResponseWriter, r *http.Request) {
	devices := make(map[string]discover.CacheEntry)

	if s.discoverer != nil {
		// Device ids can't be marshalled as keys so we need to manually
		// rebuild this map using strings. Discoverer may be nil if discovery
		// has not started yet.
		for device, entry := range s.discoverer.Cache() {
			devices[device.String()] = entry
		}
	}

	sendJSON(w, devices)
}

func (s *apiService) getReport(w http.ResponseWriter, r *http.Request) {
	sendJSON(w, reportData(s.cfg, s.model))
}

func (s *apiService) getDBIgnores(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()

	ignores, patterns, err := s.model.GetIgnores(qs.Get("folder"))
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	sendJSON(w, map[string][]string{
		"ignore":   ignores,
		"expanded": patterns,
	})
}

func (s *apiService) postDBIgnores(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()

	bs, err := ioutil.ReadAll(r.Body)
	r.Body.Close()
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	var data map[string][]string
	err = json.Unmarshal(bs, &data)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	err = s.model.SetIgnores(qs.Get("folder"), data["ignore"])
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	s.getDBIgnores(w, r)
}

func (s *apiService) getEvents(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	sinceStr := qs.Get("since")
	limitStr := qs.Get("limit")
	since, _ := strconv.Atoi(sinceStr)
	limit, _ := strconv.Atoi(limitStr)

	s.fss.gotEventRequest()

	// Flush before blocking, to indicate that we've received the request and
	// that it should not be retried. Must set Content-Type header before
	// flushing.
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	f := w.(http.Flusher)
	f.Flush()

	evs := s.eventSub.Since(since, nil)
	if 0 < limit && limit < len(evs) {
		evs = evs[len(evs)-limit:]
	}

	sendJSON(w, evs)
}

func (s *apiService) getSystemUpgrade(w http.ResponseWriter, r *http.Request) {
	if noUpgrade {
		http.Error(w, upgrade.ErrUpgradeUnsupported.Error(), 500)
		return
	}
	rel, err := upgrade.LatestRelease(s.cfg.Options().ReleasesURL, Version)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	res := make(map[string]interface{})
	res["running"] = Version
	res["latest"] = rel.Tag
	res["newer"] = upgrade.CompareVersions(rel.Tag, Version) == upgrade.Newer
	res["majorNewer"] = upgrade.CompareVersions(rel.Tag, Version) == upgrade.MajorNewer

	sendJSON(w, res)
}

func (s *apiService) getDeviceID(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	idStr := qs.Get("id")
	id, err := protocol.DeviceIDFromString(idStr)

	if err == nil {
		sendJSON(w, map[string]string{
			"id": id.String(),
		})
	} else {
		sendJSON(w, map[string]string{
			"error": err.Error(),
		})
	}
}

func (s *apiService) getLang(w http.ResponseWriter, r *http.Request) {
	lang := r.Header.Get("Accept-Language")
	var langs []string
	for _, l := range strings.Split(lang, ",") {
		parts := strings.SplitN(l, ";", 2)
		langs = append(langs, strings.ToLower(strings.TrimSpace(parts[0])))
	}
	sendJSON(w, langs)
}

func (s *apiService) postSystemUpgrade(w http.ResponseWriter, r *http.Request) {
	rel, err := upgrade.LatestRelease(s.cfg.Options().ReleasesURL, Version)
	if err != nil {
		l.Warnln("getting latest release:", err)
		http.Error(w, err.Error(), 500)
		return
	}

	if upgrade.CompareVersions(rel.Tag, Version) > upgrade.Equal {
		err = upgrade.To(rel)
		if err != nil {
			l.Warnln("upgrading:", err)
			http.Error(w, err.Error(), 500)
			return
		}

		s.flushResponse(`{"ok": "restarting"}`, w)
		l.Infoln("Upgrading")
		stop <- exitUpgrading
	}
}

func (s *apiService) postSystemPause(w http.ResponseWriter, r *http.Request) {
	var qs = r.URL.Query()
	var deviceStr = qs.Get("device")

	device, err := protocol.DeviceIDFromString(deviceStr)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	s.model.PauseDevice(device)
}

func (s *apiService) postSystemResume(w http.ResponseWriter, r *http.Request) {
	var qs = r.URL.Query()
	var deviceStr = qs.Get("device")

	device, err := protocol.DeviceIDFromString(deviceStr)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	s.model.ResumeDevice(device)
}

func (s *apiService) postDBScan(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	folder := qs.Get("folder")
	if folder != "" {
		nextStr := qs.Get("next")
		next, err := strconv.Atoi(nextStr)
		if err == nil {
			s.model.DelayScan(folder, time.Duration(next)*time.Second)
		}

		subs := qs["sub"]
		err = s.model.ScanFolderSubs(folder, subs)
		if err != nil {
			http.Error(w, err.Error(), 500)
			return
		}
	} else {
		errors := s.model.ScanFolders()
		if len(errors) > 0 {
			http.Error(w, "Error scanning folders", 500)
			sendJSON(w, errors)
			return
		}
	}
}

func (s *apiService) postDBPrio(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	folder := qs.Get("folder")
	file := qs.Get("file")
	s.model.BringToFront(folder, file)
	s.getDBNeed(w, r)
}

func (s *apiService) getQR(w http.ResponseWriter, r *http.Request) {
	var qs = r.URL.Query()
	var text = qs.Get("text")
	code, err := qr.Encode(text, qr.M)
	if err != nil {
		http.Error(w, "Invalid", 500)
		return
	}

	w.Header().Set("Content-Type", "image/png")
	w.Write(code.PNG())
}

func (s *apiService) getPeerCompletion(w http.ResponseWriter, r *http.Request) {
	tot := map[string]float64{}
	count := map[string]float64{}

	for _, folder := range s.cfg.Folders() {
		for _, device := range folder.DeviceIDs() {
			deviceStr := device.String()
			if s.model.ConnectedTo(device) {
				tot[deviceStr] += s.model.Completion(device, folder.ID)
			} else {
				tot[deviceStr] = 0
			}
			count[deviceStr]++
		}
	}

	comp := map[string]int{}
	for device := range tot {
		comp[device] = int(tot[device] / count[device])
	}

	sendJSON(w, comp)
}

func (s *apiService) getSystemBrowse(w http.ResponseWriter, r *http.Request) {
	qs := r.URL.Query()
	current := qs.Get("current")
	search, _ := osutil.ExpandTilde(current)
	pathSeparator := string(os.PathSeparator)
	if strings.HasSuffix(current, pathSeparator) && !strings.HasSuffix(search, pathSeparator) {
		search = search + pathSeparator
	}
	subdirectories, _ := osutil.Glob(search + "*")
	ret := make([]string, 0, 10)
	for _, subdirectory := range subdirectories {
		info, err := os.Stat(subdirectory)
		if err == nil && info.IsDir() {
			ret = append(ret, subdirectory+pathSeparator)
			if len(ret) > 9 {
				break
			}
		}
	}

	sendJSON(w, ret)
}

type embeddedStatic struct {
	theme        string
	lastModified time.Time
	mut          sync.RWMutex
	assetDir     string
	assets       map[string][]byte
}

func (s embeddedStatic) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	file := r.URL.Path

	if file[0] == '/' {
		file = file[1:]
	}

	if len(file) == 0 {
		file = "index.html"
	}

	s.mut.RLock()
	theme := s.theme
	modified := s.lastModified
	s.mut.RUnlock()

	// Check for an override for the current theme.
	if s.assetDir != "" {
		p := filepath.Join(s.assetDir, s.theme, filepath.FromSlash(file))
		if _, err := os.Stat(p); err == nil {
			http.ServeFile(w, r, p)
			return
		}
	}

	// Check for a compiled in asset for the current theme.
	bs, ok := s.assets[theme+"/"+file]
	if !ok {
		// Check for an overridden default asset.
		if s.assetDir != "" {
			p := filepath.Join(s.assetDir, config.DefaultTheme, filepath.FromSlash(file))
			if _, err := os.Stat(p); err == nil {
				http.ServeFile(w, r, p)
				return
			}
		}

		// Check for a compiled in default asset.
		bs, ok = s.assets[config.DefaultTheme+"/"+file]
		if !ok {
			http.NotFound(w, r)
			return
		}
	}

	modifiedSince, err := http.ParseTime(r.Header.Get("If-Modified-Since"))
	if err == nil && !modified.After(modifiedSince) {
		w.WriteHeader(http.StatusNotModified)
		return
	}

	mtype := s.mimeTypeForFile(file)
	if len(mtype) != 0 {
		w.Header().Set("Content-Type", mtype)
	}
	if strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
		w.Header().Set("Content-Encoding", "gzip")
	} else {
		// ungzip if browser not send gzip accepted header
		var gr *gzip.Reader
		gr, _ = gzip.NewReader(bytes.NewReader(bs))
		bs, _ = ioutil.ReadAll(gr)
		gr.Close()
	}
	w.Header().Set("Content-Length", fmt.Sprintf("%d", len(bs)))
	w.Header().Set("Last-Modified", modified.UTC().Format(http.TimeFormat))
	w.Header().Set("Cache-Control", "public")

	w.Write(bs)
}

func (s embeddedStatic) mimeTypeForFile(file string) string {
	// We use a built in table of the common types since the system
	// TypeByExtension might be unreliable. But if we don't know, we delegate
	// to the system.
	ext := filepath.Ext(file)
	switch ext {
	case ".htm", ".html":
		return "text/html"
	case ".css":
		return "text/css"
	case ".js":
		return "application/javascript"
	case ".json":
		return "application/json"
	case ".png":
		return "image/png"
	case ".ttf":
		return "application/x-font-ttf"
	case ".woff":
		return "application/x-font-woff"
	case ".svg":
		return "image/svg+xml"
	default:
		return mime.TypeByExtension(ext)
	}
}

// VerifyConfiguration implements the config.Committer interface
func (s *embeddedStatic) VerifyConfiguration(from, to config.Configuration) error {
	return nil
}

// CommitConfiguration implements the config.Committer interface
func (s *embeddedStatic) CommitConfiguration(from, to config.Configuration) bool {
	s.mut.Lock()
	if s.theme != to.GUI.Theme {
		s.theme = to.GUI.Theme
		s.lastModified = time.Now()
	}
	s.mut.Unlock()

	return true
}

func (s *embeddedStatic) String() string {
	return fmt.Sprintf("embeddedStatic@%p", s)
}

func (s *apiService) toNeedSlice(fs []db.FileInfoTruncated) []jsonDBFileInfo {
	res := make([]jsonDBFileInfo, len(fs))
	for i, f := range fs {
		res[i] = jsonDBFileInfo(f)
	}
	return res
}

// Type wrappers for nice JSON serialization

type jsonFileInfo protocol.FileInfo

func (f jsonFileInfo) MarshalJSON() ([]byte, error) {
	return json.Marshal(map[string]interface{}{
		"name":         f.Name,
		"size":         protocol.FileInfo(f).Size(),
		"flags":        fmt.Sprintf("%#o", f.Flags),
		"modified":     time.Unix(f.Modified, 0),
		"localVersion": f.LocalVersion,
		"numBlocks":    len(f.Blocks),
		"version":      jsonVersionVector(f.Version),
	})
}

type jsonDBFileInfo db.FileInfoTruncated

func (f jsonDBFileInfo) MarshalJSON() ([]byte, error) {
	return json.Marshal(map[string]interface{}{
		"name":         f.Name,
		"size":         db.FileInfoTruncated(f).Size(),
		"flags":        fmt.Sprintf("%#o", f.Flags),
		"modified":     time.Unix(f.Modified, 0),
		"localVersion": f.LocalVersion,
		"version":      jsonVersionVector(f.Version),
	})
}

type jsonVersionVector protocol.Vector

func (v jsonVersionVector) MarshalJSON() ([]byte, error) {
	res := make([]string, len(v))
	for i, c := range v {
		res[i] = fmt.Sprintf("%v:%d", c.ID, c.Value)
	}
	return json.Marshal(res)
}

func dirNames(dir string) []string {
	fd, err := os.Open(dir)
	if err != nil {
		return nil
	}
	defer fd.Close()

	fis, err := fd.Readdir(-1)
	if err != nil {
		return nil
	}

	var dirs []string
	for _, fi := range fis {
		if fi.IsDir() {
			dirs = append(dirs, filepath.Base(fi.Name()))
		}
	}

	sort.Strings(dirs)
	return dirs
}