Add session support (fixes #611)

cmd/syncthing/gui.go

@@ -5,13 +5,10 @@
 package main
 
 import (
-	"bytes"
 	"crypto/tls"
-	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
-	"math/rand"
 	"mime"
 	"net"
 	"net/http"
@@ -44,7 +41,6 @@ var (
 	configInSync = true
 	guiErrors    = []guiError{}
 	guiErrorsMut sync.Mutex
-	apiKey       string
 	modt         = time.Now().UTC().Format(http.TimeFormat)
 	eventSub     *events.BufferedSubscription
 )
@@ -88,9 +84,6 @@ func startGUI(cfg config.GUIConfiguration, assetDir string, m *model.Model) erro
 		}
 	}
 
-	apiKey = cfg.APIKey
-	loadCsrfTokens()
-
 	// The GET handlers
 	getRestMux := http.NewServeMux()
 	getRestMux.HandleFunc("/rest/completion", withModel(m, restGetCompletion))
@@ -141,14 +134,14 @@ func startGUI(cfg config.GUIConfiguration, assetDir string, m *model.Model) erro
 
 	// Wrap everything in CSRF protection. The /rest prefix should be
 	// protected, other requests will grant cookies.
-	handler := csrfMiddleware("/rest", mux)
+	handler := csrfMiddleware("/rest", cfg.APIKey, mux)
 
 	// Add our version as a header to responses
 	handler = withVersionMiddleware(handler)
 
 	// Wrap everything in basic auth, if user/password is set.
 	if len(cfg.User) > 0 {
-		handler = basicAuthMiddleware(cfg.User, cfg.Password, handler)
+		handler = basicAuthAndSessionMiddleware(cfg, handler)
 	}
 
 	go http.Serve(listener, handler)
@@ -600,56 +593,6 @@ func restGetPeerCompletion(m *model.Model, w http.ResponseWriter, r *http.Reques
 	json.NewEncoder(w).Encode(comp)
 }
 
-func basicAuthMiddleware(username string, passhash string, next http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if validAPIKey(r.Header.Get("X-API-Key")) {
-			next.ServeHTTP(w, r)
-			return
-		}
-
-		error := func() {
-			time.Sleep(time.Duration(rand.Intn(100)+100) * time.Millisecond)
-			w.Header().Set("WWW-Authenticate", "Basic realm=\"Authorization Required\"")
-			http.Error(w, "Not Authorized", http.StatusUnauthorized)
-		}
-
-		hdr := r.Header.Get("Authorization")
-		if !strings.HasPrefix(hdr, "Basic ") {
-			error()
-			return
-		}
-
-		hdr = hdr[6:]
-		bs, err := base64.StdEncoding.DecodeString(hdr)
-		if err != nil {
-			error()
-			return
-		}
-
-		fields := bytes.SplitN(bs, []byte(":"), 2)
-		if len(fields) != 2 {
-			error()
-			return
-		}
-
-		if string(fields[0]) != username {
-			error()
-			return
-		}
-
-		if err := bcrypt.CompareHashAndPassword([]byte(passhash), fields[1]); err != nil {
-			error()
-			return
-		}
-
-		next.ServeHTTP(w, r)
-	})
-}
-
-func validAPIKey(k string) bool {
-	return len(apiKey) > 0 && k == apiKey
-}
-
 func embeddedStatic(assetDir string) http.Handler {
 	assets := auto.Assets()
 

cmd/syncthing/gui_auth.go

@@ -0,0 +1,95 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"math/rand"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"code.google.com/p/go.crypto/bcrypt"
+	"github.com/syncthing/syncthing/config"
+	"github.com/syncthing/syncthing/osutil"
+)
+
+var (
+	sessions    = make(map[string]bool)
+	sessionsMut sync.Mutex
+)
+
+func basicAuthAndSessionMiddleware(cfg config.GUIConfiguration, next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if cfg.APIKey != "" && r.Header.Get("X-API-Key") == cfg.APIKey {
+			next.ServeHTTP(w, r)
+			return
+		}
+
+		cookie, err := r.Cookie("sessionid")
+		if err == nil && cookie != nil {
+			sessionsMut.Lock()
+			_, ok := sessions[cookie.Value]
+			sessionsMut.Unlock()
+			if ok {
+				next.ServeHTTP(w, r)
+				return
+			}
+		}
+
+		error := func() {
+			time.Sleep(time.Duration(rand.Intn(100)+100) * time.Millisecond)
+			w.Header().Set("WWW-Authenticate", "Basic realm=\"Authorization Required\"")
+			http.Error(w, "Not Authorized", http.StatusUnauthorized)
+		}
+
+		hdr := r.Header.Get("Authorization")
+		if !strings.HasPrefix(hdr, "Basic ") {
+			error()
+			return
+		}
+
+		hdr = hdr[6:]
+		bs, err := base64.StdEncoding.DecodeString(hdr)
+		if err != nil {
+			error()
+			return
+		}
+
+		fields := bytes.SplitN(bs, []byte(":"), 2)
+		if len(fields) != 2 {
+			error()
+			return
+		}
+
+		if string(fields[0]) != cfg.User {
+			error()
+			return
+		}
+
+		if err := bcrypt.CompareHashAndPassword([]byte(cfg.Password), fields[1]); err != nil {
+			error()
+			return
+		}
+
+		sessionid := randomString(32)
+		sessionsMut.Lock()
+		sessions[sessionid] = true
+		sessionsMut.Unlock()
+		http.SetCookie(w, &http.Cookie{
+			Name:   "sessionid",
+			Value:  sessionid,
+			MaxAge: 0,
+		})
+
+		next.ServeHTTP(w, r)
+	})
+}

cmd/syncthing/gui_csrf.go

@@ -25,10 +25,11 @@ var csrfMut sync.Mutex
 // Check for CSRF token on /rest/ URLs. If a correct one is not given, reject
 // the request with 403. For / and /index.html, set a new CSRF cookie if none
 // is currently set.
-func csrfMiddleware(prefix string, next http.Handler) http.Handler {
+func csrfMiddleware(prefix, apiKey string, next http.Handler) http.Handler {
+	loadCsrfTokens()
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Allow requests carrying a valid API key
-		if validAPIKey(r.Header.Get("X-API-Key")) {
+		if apiKey != "" && r.Header.Get("X-API-Key") == apiKey {
 			next.ServeHTTP(w, r)
 			return
 		}
@@ -76,13 +77,7 @@ func validCsrfToken(token string) bool {
 }
 
 func newCsrfToken() string {
-	bs := make([]byte, 30)
-	_, err := rand.Reader.Read(bs)
-	if err != nil {
-		l.Fatalln(err)
-	}
-
-	token := base64.StdEncoding.EncodeToString(bs)
+	token := randomString(30)
 
 	csrfMut.Lock()
 	csrfTokens = append(csrfTokens, token)
@@ -134,3 +129,13 @@ func loadCsrfTokens() {
 		csrfTokens = append(csrfTokens, s.Text())
 	}
 }
+
+func randomString(len int) string {
+	bs := make([]byte, len)
+	_, err := rand.Reader.Read(bs)
+	if err != nil {
+		l.Fatalln(err)
+	}
+
+	return base64.StdEncoding.EncodeToString(bs)
+}