Security Guards

Guards intercept every incoming request before it reaches a route handler. If a guard returns False, Nidus raises EUnauthorizedException (HTTP 401) and stops processing immediately.

Registering a guard

GetNidus
  .UseGuard(
    function: Boolean
    begin
      // Return True to allow, False to deny
      Result := ValidateJWT(GetNidus.Request.Authorization);
    end)
  .Start(TAppModule.Create);

UseGuard accepts a TGuardCallback — a reference function that returns Boolean. The callback is stored in TNidus.FGuardCallback and evaluated on each call to LoadRouteModule.

How it fits in the request pipeline

LoadRouteModule(path, request)
  │
  ├── [guard set?] → FGuardCallback()
  │       └── False → raise EUnauthorizedException (HTTP 401)
  │
  ├── [pipe set?]  → Pipe.Validate(routeHandler, request)
  │       └── messages? → return TReturnPair.Failure(EBadRequestException)
  │
  └── RouteParse.SelectRoute(path, request) → success

Source: TNidus.LoadRouteModule in Nidus.pas.

Accessing request data inside a guard

Inside the guard callback, use GetNidus.Request to inspect the current IRouteRequest:

.UseGuard(
  function: Boolean
  var LReq: IRouteRequest;
  begin
    LReq := GetNidus.Request;
    Result := (LReq <> nil) and CheckToken(LReq.Authorization);
  end)

IRouteRequest (defined in Nidus.Request) exposes the following methods:

Method	Return type	Description
Header	TRequestData	Request headers
Params	TRequestData	Route parameters
Querys	TRequestData	Query-string parameters
Body	string	Raw request body
Host	string	Host name
ContentType	string	Content-Type header value
Method	string	HTTP method (GET, POST, …)
URL	string	Full request URL
Port	integer	Server port
Authorization	string	Authorization header value
AsObject	TObject	Deserialized body object (set by TParseJsonPipe)

Exception types

Exception	HTTP status	Raised by
EUnauthorizedException	401	Guard returns False
EBadRequestException	400	Validation pipe failure
ENidusException (base)	status from .Status	Any Nidus exception

Source: Nidus.Exception.