package alps import ( "encoding/json" "fmt" "log" "net/http" "net/url" "strings" "sync" "time" "github.com/fernet/fernet-go" "github.com/labstack/echo/v4" ) const ( cookieName = "alps_session" loginTokenCookieName = "alps_login_token" ) // Server holds all the alps server state. type Server struct { e *echo.Echo Sessions *SessionManager Options *Options mutex sync.RWMutex // used for server reload plugins []Plugin // maps protocols to URLs (protocol can be empty for auto-discovery) upstreams map[string]*url.URL imap struct { host string tls bool insecure bool } smtp struct { host string tls bool insecure bool } } func newServer(e *echo.Echo, options *Options) (*Server, error) { s := &Server{e: e, Options: options} s.upstreams = make(map[string]*url.URL, len(options.Upstreams)) for _, upstream := range options.Upstreams { u, err := parseUpstream(upstream) if err != nil { return nil, fmt.Errorf("failed to parse upstream %q: %v", upstream, err) } if _, ok := s.upstreams[u.Scheme]; ok { return nil, fmt.Errorf("found two upstream servers for scheme %q", u.Scheme) } s.upstreams[u.Scheme] = u } if err := s.parseIMAPUpstream(); err != nil { return nil, err } if err := s.parseSMTPUpstream(); err != nil { return nil, err } s.Sessions = newSessionManager(s.dialIMAP, s.dialSMTP, e.Logger, options.Debug) return s, nil } func (s *Server) Close() { s.Sessions.Close() } func parseUpstream(s string) (*url.URL, error) { if !strings.ContainsAny(s, ":/") { // This is a raw domain name, make it an URL with an empty scheme s = "//" + s } return url.Parse(s) } type NoUpstreamError struct { schemes []string } func (err *NoUpstreamError) Error() string { return fmt.Sprintf("no upstream server configured for schemes %v", err.schemes) } // Upstream retrieves the configured upstream server URL for the provided // schemes. If no configured upstream server matches, a *NoUpstreamError is // returned. An empty URL.Scheme means that the caller needs to perform // auto-discovery with URL.Host. func (s *Server) Upstream(schemes ...string) (*url.URL, error) { var urls []*url.URL for _, scheme := range append(schemes, "") { u, ok := s.upstreams[scheme] if ok { urls = append(urls, u) } } if len(urls) == 0 { return nil, &NoUpstreamError{schemes} } if len(urls) > 1 { return nil, fmt.Errorf("multiple upstream servers are configured for schemes %v", schemes) } return urls[0], nil } func (s *Server) parseIMAPUpstream() error { u, err := s.Upstream("imap", "imaps", "imap+insecure") if err != nil { return fmt.Errorf("failed to parse upstream IMAP server: %v", err) } if u.Scheme == "" { u, err = discoverIMAP(u.Host) if err != nil { return fmt.Errorf("failed to discover IMAP server: %v", err) } } switch u.Scheme { case "imaps": s.imap.tls = true case "imap+insecure": s.imap.insecure = true } s.imap.host = u.Host if !strings.ContainsRune(s.imap.host, ':') { if u.Scheme == "imaps" { s.imap.host += ":993" } else { s.imap.host += ":143" } } c, err := s.dialIMAP() if err != nil { return fmt.Errorf("failed to connect to IMAP server: %v", err) } c.Close() s.e.Logger.Printf("Configured upstream IMAP server: %v", u) return nil } func (s *Server) parseSMTPUpstream() error { u, err := s.Upstream("smtp", "smtps", "smtp+insecure") if _, ok := err.(*NoUpstreamError); ok { return nil } else if err != nil { return fmt.Errorf("failed to parse upstream SMTP server: %v", err) } if u.Scheme == "" { u, err = discoverSMTP(u.Host) if err != nil { s.e.Logger.Printf("Failed to discover SMTP server: %v", err) return nil } } switch u.Scheme { case "smtps": s.smtp.tls = true case "smtp+insecure": s.smtp.insecure = true } s.smtp.host = u.Host if !strings.ContainsRune(s.smtp.host, ':') { if u.Scheme == "smtps" { s.smtp.host += ":465" } else { s.smtp.host += ":587" } } c, err := s.dialSMTP() if err != nil { return fmt.Errorf("failed to connect to SMTP server: %v", err) } c.Close() s.e.Logger.Printf("Configured upstream SMTP server: %v", u) return nil } func (s *Server) load() error { var plugins []Plugin for _, load := range pluginLoaders { l, err := load(s) if err != nil { return fmt.Errorf("failed to load plugins: %v", err) } for _, p := range l { s.e.Logger.Printf("Loaded plugin %q", p.Name()) } plugins = append(plugins, l...) } renderer := newRenderer(s.e.Logger, s.Options.Theme) if err := renderer.Load(plugins); err != nil { return fmt.Errorf("failed to load templates: %v", err) } // Once we've loaded plugins and templates from disk (which can take time), // swap them in the Server struct s.mutex.Lock() defer s.mutex.Unlock() // Close previous plugins for _, p := range s.plugins { if err := p.Close(); err != nil { s.e.Logger.Printf("Failed to unload plugin %q: %v", p.Name(), err) } } s.plugins = plugins s.e.Renderer = renderer for _, p := range plugins { p.SetRoutes(s.e.Group("")) } return nil } // Reload loads Lua plugins and templates from disk. func (s *Server) Reload() error { s.e.Logger.Printf("Reloading server") return s.load() } // Logger returns this server's logger. func (s *Server) Logger() echo.Logger { return s.e.Logger } // Context is the context used by HTTP handlers. // // Use a type assertion to get it from a echo.Context: // // ctx := ectx.(*alps.Context) type Context struct { echo.Context Server *Server Session *Session // nil if user isn't logged in } var aLongTimeAgo = time.Unix(233431200, 0) // SetSession sets a cookie for the provided session. Passing a nil session // unsets the cookie. func (ctx *Context) SetSession(s *Session) { cookie := http.Cookie{ Name: cookieName, HttpOnly: true, SameSite: http.SameSiteStrictMode, Secure: ctx.IsTLS(), } if s != nil { cookie.Value = s.token } else { cookie.Expires = aLongTimeAgo // unset the cookie } ctx.SetCookie(&cookie) } type loginToken struct { Username string Password string } func (ctx *Context) SetLoginToken(username, password string) { cookie := http.Cookie{ Expires: time.Now().Add(30 * 24 * time.Hour), Name: loginTokenCookieName, HttpOnly: true, SameSite: http.SameSiteStrictMode, Secure: ctx.IsTLS(), Path: "/login", } if username == "" { cookie.Expires = aLongTimeAgo // unset the cookie ctx.SetCookie(&cookie) return } loginToken := loginToken{username, password} payload, err := json.Marshal(loginToken) if err != nil { panic(err) // Should never happen } fkey := ctx.Server.Options.LoginKey if fkey == nil { return } bytes, err := fernet.EncryptAndSign(payload, fkey) if err != nil { log.Printf("Warning: login token encryption failed: %v", err) return } cookie.Value = string(bytes) ctx.SetCookie(&cookie) } func (ctx *Context) GetLoginToken() (string, string) { cookie, err := ctx.Cookie(loginTokenCookieName) if err != nil || cookie == nil { return "", "" } fkey := ctx.Server.Options.LoginKey if fkey == nil { return "", "" } bytes := fernet.VerifyAndDecrypt([]byte(cookie.Value), 24*time.Hour*30, []*fernet.Key{fkey}) if bytes == nil { return "", "" } var token loginToken err = json.Unmarshal(bytes, &token) if err != nil { panic(err) // Should never happen } return token.Username, token.Password } func isPublic(path string) bool { if strings.HasPrefix(path, "/plugins/") { parts := strings.Split(path, "/") return len(parts) >= 4 && parts[3] == "assets" } return path == "/login" || strings.HasPrefix(path, "/themes/") } func redirectToLogin(ctx *Context) error { path := ctx.Request().URL.Path to := "/login" if path != "/" && path != "/login" { to += "?next=" + url.QueryEscape(ctx.Request().URL.String()) } return ctx.Redirect(http.StatusFound, to) } func handleUnauthenticated(next echo.HandlerFunc, ctx *Context) error { // Require auth for all requests except /login and assets if isPublic(ctx.Request().URL.Path) { return next(ctx) } else { return redirectToLogin(ctx) } } type Options struct { Upstreams []string Theme string Debug bool LoginKey *fernet.Key } // New creates a new server. func New(e *echo.Echo, options *Options) (*Server, error) { s, err := newServer(e, options) if err != nil { return nil, err } if err := s.load(); err != nil { return nil, err } e.HTTPErrorHandler = func(err error, c echo.Context) { code := http.StatusInternalServerError if he, ok := err.(*echo.HTTPError); ok { code = he.Code } else { c.Logger().Error(err) } // TODO: hide internal errors c.String(code, err.Error()) } e.Pre(func(next echo.HandlerFunc) echo.HandlerFunc { return func(ectx echo.Context) error { s.mutex.RLock() err := next(ectx) s.mutex.RUnlock() return err } }) e.Use(func(next echo.HandlerFunc) echo.HandlerFunc { return func(ectx echo.Context) error { // `style-src 'unsafe-inline'` is required for e-mails with // embedded stylesheets ectx.Response().Header().Set("Content-Security-Policy", "default-src 'self'; style-src 'self' 'unsafe-inline'") // DNS prefetching has privacy implications ectx.Response().Header().Set("X-DNS-Prefetch-Control", "off") return next(ectx) } }) e.Use(func(next echo.HandlerFunc) echo.HandlerFunc { return func(ectx echo.Context) error { ctx := &Context{Context: ectx, Server: s} ctx.Set("context", ctx) cookie, err := ctx.Cookie(cookieName) if err == http.ErrNoCookie { return handleUnauthenticated(next, ctx) } else if err != nil { return err } ctx.Session, err = ctx.Server.Sessions.get(cookie.Value) if err == ErrSessionExpired { ctx.SetSession(nil) return handleUnauthenticated(next, ctx) } else if err != nil { return err } ctx.Session.ping() return next(ctx) } }) e.Static("/themes", "themes") return s, nil }