Open the {{.AppName}} app and approve this request. Keep this page open.
Open {{.AppName}}{{if .MatchCode}}When prompted, select this emoji in {{.AppName}}:
Waiting for approval…
This request expires at {{.ExpiresAt}}.
Login could not be started.
`)) func (h *Handler) authorizationError(w http.ResponseWriter, r *http.Request, values map[string]string, cause error) { target, safe, err := h.service.ResolveAuthorizationErrorTarget(r.Context(), values["client_id"], values["response_type"], values["redirect_uri"], values["origin"]) if err != nil || !safe { if err != nil { h.logger.Error("telegram_login_authorize_error_target_failed", zap.String("error", errorClass(err))) } h.authorizationRequestError(w) return } code := "invalid_request" switch { case errors.Is(cause, domain.ErrTelegramLoginScopeInvalid): code = "invalid_scope" case values["response_type"] != "code" && values["response_type"] != "post_message": code = "unsupported_response_type" default: // Known validation failures use invalid_request. Unknown failures are // reported as server_error without exposing their details. if strings.HasPrefix(errorClass(cause), "internal_") { code = "server_error" } } state := values["state"] if len(state) > 2048 { state = "" } if target.ResponseType == "code" { redirectURL, err := loginapp.AppendAuthorizationError(target.RedirectURI, code, state) if err != nil { h.authorizationRequestError(w) return } w.Header().Set("Cache-Control", "no-store") http.Redirect(w, r, redirectURL, http.StatusFound) return } nonce, err := loginapp.GenerateOpaqueToken() if err != nil { h.authorizationRequestError(w) return } w.Header().Set("Cache-Control", "no-store") w.Header().Set("Content-Security-Policy", "default-src 'none'; script-src 'nonce-"+nonce+"'; frame-ancestors 'none'; base-uri 'none'") w.Header().Set("Content-Type", "text/html; charset=utf-8") w.WriteHeader(http.StatusOK) _ = authorizationErrorPage.Execute(w, struct { Nonce string Error string Origin string }{Nonce: nonce, Error: code, Origin: target.Origin}) } func (h *Handler) authorizationRequestError(w http.ResponseWriter) { w.Header().Set("Cache-Control", "no-store") w.Header().Set("Content-Type", "text/plain; charset=utf-8") http.Error(w, "Invalid Telegram Login request.", http.StatusBadRequest) } func (h *Handler) authorizationStatus(w http.ResponseWriter, r *http.Request) { w.Header().Set("Cache-Control", "no-store") w.Header().Set("Pragma", "no-cache") if !h.allow(w, r, "status", h.requestIP(r), 300, time.Minute) { return } form, ok := parseBoundedForm(w, r, maxStatusFormBytes) if !ok { return } browserToken, unique := singleValue(form, "browser_token") if !unique || browserToken == "" { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "invalid browser request") return } request, err := h.service.RequestByBrowserToken(r.Context(), browserToken) if err != nil { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "invalid browser request") return } if !h.authorizeStatusOrigin(w, r, request) { return } switch request.Status { case domain.TelegramLoginRequestPending: writeJSON(w, http.StatusOK, map[string]string{"status": "pending"}) case domain.TelegramLoginRequestApproved: if request.ResponseType == "post_message" { finalized, err := h.service.FinalizeDirectByBrowserToken(r.Context(), browserToken, h.tokens) if err != nil { h.logger.Error("telegram_login_direct_finalize_failed", zap.Int64("request_id", request.ID), zap.Error(err)) writeOAuthError(w, http.StatusInternalServerError, "server_error", "authorization could not be finalized") return } writeJSON(w, http.StatusOK, map[string]string{"status": "approved", "id_token": finalized.IDToken}) return } finalized, err := h.service.FinalizeByBrowserToken(r.Context(), browserToken) if err != nil { h.logger.Error("telegram_login_finalize_failed", zap.Int64("request_id", request.ID), zap.Error(err)) writeOAuthError(w, http.StatusInternalServerError, "server_error", "authorization could not be finalized") return } writeJSON(w, http.StatusOK, map[string]string{"status": "approved", "redirect_url": finalized.RedirectURL}) case domain.TelegramLoginRequestDeclined, domain.TelegramLoginRequestExpired: errorCode := "access_denied" status := "declined" if request.Status == domain.TelegramLoginRequestExpired { errorCode, status = "temporarily_unavailable", "expired" } if request.ResponseType == "post_message" { writeJSON(w, http.StatusOK, map[string]string{"status": status, "error": errorCode}) return } redirectURL, err := loginapp.AppendAuthorizationError(request.RedirectURI, errorCode, request.State) if err != nil { writeOAuthError(w, http.StatusInternalServerError, "server_error", "authorization could not be finalized") return } writeJSON(w, http.StatusOK, map[string]string{"status": status, "redirect_url": redirectURL}) default: writeOAuthError(w, http.StatusBadRequest, "invalid_request", "invalid browser request") } } // authorizeStatusOrigin keeps the original same-origin popup poll working and // permits the registered relying-party origin to take over polling when a // mobile browser drops window.opener during an external app round-trip. The // short-lived browser token remains a bearer credential, but browser-readable // responses are exposed only to the exact origin persisted on the request. func (h *Handler) authorizeStatusOrigin(w http.ResponseWriter, r *http.Request, request domain.TelegramLoginRequest) bool { origin := strings.TrimSpace(r.Header.Get("Origin")) if origin == "" { return true } issuerOrigin, err := loginapp.NormalizeWebOrigin(h.tokens.Issuer(), h.allowHTTP) if err == nil && origin == issuerOrigin { return true } if request.ResponseType == "post_message" && origin == request.Origin { w.Header().Set("Access-Control-Allow-Origin", origin) w.Header().Add("Vary", "Origin") return true } writeOAuthError(w, http.StatusForbidden, "access_denied", "browser origin is not authorized") return false } func (h *Handler) token(w http.ResponseWriter, r *http.Request) { if !h.allow(w, r, "token-ip", h.requestIP(r), 60, time.Minute) { return } form, ok := parseBoundedForm(w, r, maxTokenFormBytes) if !ok { return } authorizationHeaders := r.Header.Values("Authorization") var clientID, clientSecret string var publicNativeClient bool switch len(authorizationHeaders) { case 0: var unique bool clientID, unique = requiredSingleValue(form, "client_id", 64) if !unique { h.invalidClient(w) return } clientSecret, unique = optionalSingleValue(form, "client_secret") if !unique || len(clientSecret) > 1024 { h.invalidClient(w) return } publicNativeClient = clientSecret == "" case 1: var ok bool clientID, clientSecret, ok = r.BasicAuth() if !ok || clientID == "" || clientSecret == "" || len(clientID) > 64 || len(clientSecret) > 1024 { h.invalidClient(w) return } if _, supplied := form["client_secret"]; supplied { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "multiple client authentication methods are not allowed") return } default: h.invalidClient(w) return } if !h.allow(w, r, "token-client", clientID, 60, time.Minute) { return } formClientID, unique := optionalSingleValue(form, "client_id") if !unique || (formClientID != "" && formClientID != clientID) { h.invalidClient(w) return } grantType, okGrant := requiredSingleValue(form, "grant_type", 64) if !okGrant { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "grant_type is required") return } if grantType != "authorization_code" { writeOAuthError(w, http.StatusBadRequest, "unsupported_grant_type", "only authorization_code is supported") return } code, okCode := requiredSingleValue(form, "code", 1024) redirectURI, okRedirect := requiredSingleValue(form, "redirect_uri", 4096) codeVerifier, okVerifier := requiredSingleValue(form, "code_verifier", 128) if !okCode || !okRedirect || !okVerifier { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "code, redirect_uri and code_verifier are required") return } // Generate every response artifact before consuming the one-time code. A // transient entropy failure must leave the grant retryable. accessToken, err := loginapp.GenerateOpaqueToken() if err != nil { h.logger.Error("telegram_login_access_token_failed", zap.Error(err)) writeOAuthError(w, http.StatusInternalServerError, "server_error", "token service unavailable") return } issued, err := h.service.ExchangeAuthorizationCodeAndIssue(r.Context(), loginapp.ExchangeAuthorizationCodeParams{ Code: code, ClientID: clientID, ClientSecret: clientSecret, RedirectURI: redirectURI, CodeVerifier: codeVerifier, PublicNativeClient: publicNativeClient, }, h.tokens) if err != nil { switch { case errors.Is(err, domain.ErrTelegramLoginSecretInvalid), errors.Is(err, domain.ErrTelegramLoginClientDisabled): h.invalidClient(w) case errors.Is(err, domain.ErrTelegramLoginCodeInvalid), errors.Is(err, domain.ErrTelegramLoginCodeConsumed), errors.Is(err, domain.ErrTelegramLoginPKCEInvalid), errors.Is(err, domain.ErrTelegramLoginURLInvalid): writeOAuthError(w, http.StatusBadRequest, "invalid_grant", "authorization code is invalid or expired") default: h.logger.Error("telegram_login_token_exchange_failed", zap.String("error", errorClass(err))) writeOAuthError(w, http.StatusInternalServerError, "server_error", "token service unavailable") } return } _ = issued.WebAuthorization // durable authorization is intentionally not encoded into the opaque access token. w.Header().Set("Cache-Control", "no-store") w.Header().Set("Pragma", "no-cache") writeJSON(w, http.StatusOK, map[string]any{ "access_token": accessToken, "token_type": "Bearer", "expires_in": int64(h.tokens.TTL().Seconds()), "id_token": issued.IDToken, }) } func (h *Handler) invalidClient(w http.ResponseWriter) { w.Header().Set("WWW-Authenticate", `Basic realm="telegram-login-token", charset="UTF-8"`) writeOAuthError(w, http.StatusUnauthorized, "invalid_client", "client authentication failed") } func parseBoundedForm(w http.ResponseWriter, r *http.Request, maxBytes int64) (url.Values, bool) { mediaType, _, err := mime.ParseMediaType(r.Header.Get("Content-Type")) if err != nil || mediaType != "application/x-www-form-urlencoded" { writeOAuthError(w, http.StatusUnsupportedMediaType, "invalid_request", "form content type is required") return nil, false } r.Body = http.MaxBytesReader(w, r.Body, maxBytes) body, err := io.ReadAll(r.Body) if err != nil { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "request body is invalid") return nil, false } form, err := url.ParseQuery(string(body)) if err != nil { writeOAuthError(w, http.StatusBadRequest, "invalid_request", "request body is invalid") return nil, false } return form, true } func singleValue(values url.Values, key string) (string, bool) { items, exists := values[key] if !exists { return "", true } if len(items) != 1 { return "", false } return items[0], true } func optionalSingleValue(values url.Values, key string) (string, bool) { value, ok := singleValue(values, key) return value, ok } func requiredSingleValue(values url.Values, key string, max int) (string, bool) { value, ok := singleValue(values, key) return value, ok && value != "" && len(value) <= max } func boundedHeader(value, fallback string, max int) string { value = strings.TrimSpace(strings.ToValidUTF8(value, "�")) if value == "" { value = fallback } for len(value) > max { _, size := utf8.DecodeLastRuneInString(value) value = value[:len(value)-size] } return value } func (h *Handler) requestIP(r *http.Request) string { remote, ok := parseRequestIP(r.RemoteAddr) if !ok { return "Unknown IP" } if !prefixContains(h.trustedProxies, remote) { return remote.String() } forwarded := strings.Split(r.Header.Get("X-Forwarded-For"), ",") for i := len(forwarded) - 1; i >= 0; i-- { candidate, ok := parseRequestIP(strings.TrimSpace(forwarded[i])) if !ok { continue } remote = candidate if !prefixContains(h.trustedProxies, candidate) { return candidate.String() } } if candidate, ok := parseRequestIP(strings.TrimSpace(r.Header.Get("X-Real-IP"))); ok { return candidate.String() } return remote.String() } func parseRequestIP(raw string) (netip.Addr, bool) { if addrPort, err := netip.ParseAddrPort(raw); err == nil { return addrPort.Addr().Unmap(), true } if host, _, err := net.SplitHostPort(raw); err == nil { raw = host } addr, err := netip.ParseAddr(strings.Trim(raw, "[]")) return addr.Unmap(), err == nil } func prefixContains(prefixes []netip.Prefix, addr netip.Addr) bool { for _, prefix := range prefixes { if prefix.Contains(addr) { return true } } return false } func (h *Handler) allow(w http.ResponseWriter, r *http.Request, bucket, subject string, limit int, window time.Duration) bool { if h.limiter == nil { return true } sum := sha256.Sum256([]byte(subject)) key := "telegram-login-http:" + bucket + ":" + base64.RawURLEncoding.EncodeToString(sum[:]) allowed, retryAfter, err := h.limiter.Allow(r.Context(), key, limit, window) if err != nil { h.logger.Error("telegram_login_rate_limit_failed", zap.String("bucket", bucket), zap.Error(err)) writeOAuthError(w, http.StatusServiceUnavailable, "temporarily_unavailable", "login service temporarily unavailable") return false } if allowed { return true } if retryAfter <= 0 { retryAfter = 1 } w.Header().Set("Retry-After", fmt.Sprintf("%d", retryAfter)) writeOAuthError(w, http.StatusTooManyRequests, "temporarily_unavailable", "too many login requests") return false } func writeJSON(w http.ResponseWriter, status int, value any) { w.Header().Set("Content-Type", "application/json") w.WriteHeader(status) _ = json.NewEncoder(w).Encode(value) } func writeOAuthError(w http.ResponseWriter, status int, code, description string) { w.Header().Set("Cache-Control", "no-store") w.Header().Set("Pragma", "no-cache") writeJSON(w, status, map[string]string{"error": code, "error_description": description}) } func errorClass(err error) string { for _, candidate := range []struct { target error name string }{ {domain.ErrTelegramLoginClientInvalid, "client_invalid"}, {domain.ErrTelegramLoginClientDisabled, "client_disabled"}, {domain.ErrTelegramLoginRedirectNotAllowed, "redirect_not_allowed"}, {domain.ErrTelegramLoginOriginNotAllowed, "origin_not_allowed"}, {domain.ErrTelegramLoginScopeInvalid, "scope_invalid"}, {domain.ErrTelegramLoginPKCEInvalid, "pkce_invalid"}, {domain.ErrTelegramLoginRequestInvalid, "request_invalid"}, } { if errors.Is(err, candidate.target) { return candidate.name } } return fmt.Sprintf("internal_%T", err) }