syncthing/cmd/syncthing/gui_auth.go
2017-02-09 08:04:16 +01:00

142 lines
3.5 KiB
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 https://mozilla.org/MPL/2.0/.
package main
import (
"bytes"
"encoding/base64"
"net/http"
"strings"
"time"
"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/events"
"github.com/syncthing/syncthing/lib/rand"
"github.com/syncthing/syncthing/lib/sync"
"golang.org/x/crypto/bcrypt"
)
var (
sessions = make(map[string]bool)
sessionsMut = sync.NewMutex()
)
func emitLoginAttempt(success bool, username string) {
events.Default.Log(events.LoginAttempt, map[string]interface{}{
"success": success,
"username": username,
})
}
func basicAuthAndSessionMiddleware(cookieName string, cfg config.GUIConfiguration, next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if cfg.IsValidAPIKey(r.Header.Get("X-API-Key")) {
next.ServeHTTP(w, r)
return
}
cookie, err := r.Cookie(cookieName)
if err == nil && cookie != nil {
sessionsMut.Lock()
_, ok := sessions[cookie.Value]
sessionsMut.Unlock()
if ok {
next.ServeHTTP(w, r)
return
}
}
httpl.Debugln("Sessionless HTTP request with authentication; this is expensive.")
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
}
// Check if the username is correct, assuming it was sent as UTF-8
username := string(fields[0])
if username == cfg.User {
goto usernameOK
}
// ... check it again, converting it from assumed ISO-8859-1 to UTF-8
username = string(iso88591ToUTF8(fields[0]))
if username == cfg.User {
goto usernameOK
}
// Neither of the possible interpretations match the configured username
emitLoginAttempt(false, username)
error()
return
usernameOK:
// Check password as given (assumes UTF-8 encoding)
password := fields[1]
if err := bcrypt.CompareHashAndPassword([]byte(cfg.Password), password); err == nil {
goto passwordOK
}
// ... check it again, converting it from assumed ISO-8859-1 to UTF-8
password = iso88591ToUTF8(password)
if err := bcrypt.CompareHashAndPassword([]byte(cfg.Password), password); err == nil {
goto passwordOK
}
// Neither of the attempts to verify the password checked out
emitLoginAttempt(false, username)
error()
return
passwordOK:
sessionid := rand.String(32)
sessionsMut.Lock()
sessions[sessionid] = true
sessionsMut.Unlock()
http.SetCookie(w, &http.Cookie{
Name: cookieName,
Value: sessionid,
MaxAge: 0,
})
emitLoginAttempt(true, username)
next.ServeHTTP(w, r)
})
}
// Convert an ISO-8859-1 encoded byte string to UTF-8. Works by the
// principle that ISO-8859-1 bytes are equivalent to unicode code points,
// that a rune slice is a list of code points, and that stringifying a slice
// of runes generates UTF-8 in Go.
func iso88591ToUTF8(s []byte) []byte {
runes := make([]rune, len(s))
for i := range s {
runes[i] = rune(s[i])
}
return []byte(string(runes))
}