# Authentication

Out of the box RestRserve provides two authentication schemas: `Basic` and `Bearer`.

## Basic

Note that Basic authentication, should only be used over HTTPS (SSL) or within secure network. In HTTP protocol `Authorization` header (as well as other parts of the HTTP request) are plain text and are not encrypted!

According to `AuthBackendBasic` documentation first of all we need to provide an authentication function. It should take 2 arguments - `user` and `password` and return `logical` value - whether access is allowed for a given user or not.

    library(RestRserve)

    allowed_access = list(
      "user-1" = "password-1",
      "user-2" = "password-2"
    )

    auth_fun = function(user, password) {
      res = FALSE
      try({
        res = identical(allowed_access[[user]], password)
      }, silent = TRUE)
      return(res)
    }

Now we can create authentication backend.

    basic_auth_backend = AuthBackendBasic$new(FUN = auth_fun)

Now let’s create application which requires authorization in order to use `/secure/factorial` endpoint:

    auth_mw = AuthMiddleware$new(
      auth_backend = basic_auth_backend,
      routes = "/secure/factorial",
      id = "auth_middleware"
    )

    app = Application$new(middleware = list(auth_mw))

Let’s add two endpoints - first public (`/factorial`) and second with restricted access (`/secure/factorial`):

    factorial_handler = function(request, response) {
      x = request$get_param_query("x")
      x = as.integer(x)
      response$set_body(factorial(x))
    }
    app$add_get("/factorial", factorial_handler)
    app$add_get("/secure/factorial", factorial_handler)

As we can see first endpoint doesn’t require any authentication:

    req = Request$new(path = "/factorial", parameters_query = list(x = "5"))
    res = app$process_request(req)
    res$body
    #> [1] 120

Let’s try to send a request without credentials to the second endpoint:

    req = Request$new(path = "/secure/factorial", parameters_query = list(x = "5"))
    res = app$process_request(req)
    res$body
    #> [1] "401 Missing Authorization Header"

As expected this gives `405` error.

Now let’s add correct credentials:

    credentials = jsonlite::base64_enc("user-1:password-1")
    headers = list("Authorization" = sprintf("Basic %s", credentials))

    req = Request$new(
      path = "/secure/factorial",
      parameters_query = list(x = "5"),
      headers = headers
    )

    res = app$process_request(req)
    res$body
    #> [1] 120

Success!

Let’s see what happens if password is wrong:

    credentials = jsonlite::base64_enc("user-1:password-2")
    headers = list("Authorization" = sprintf("Basic %s", credentials))

    req = Request$new(
      path = "/secure/factorial",
      parameters_query = list(x = "5"),
      headers = headers
    )

    res = app$process_request(req)
    res$body
    #> [1] "401 Invalid Username/Password"

## Bearer

`Bearer` authentication (also called “token” authentication) is an HTTP authentication scheme that involves security tokens called bearer tokens. The name “Bearer authentication” can be understood as “give access to the bearer of this token.” The bearer token is a cryptic string, usually generated by the server in response to a login request. The client must send this token in the Authorization header when making requests to protected resources.

The `Bearer` authentication scheme was originally created as part of `OAuth 2.0` in RFC 6750, but is sometimes also used on its own. Similarly to Basic authentication, Bearer authentication should only be used over HTTPS (SSL).

    allowed_tokens = c(
      "super_secure_token_1",
      "super_secure_token_2"
    )

    auth_fun = function(token) {
      res = FALSE
      try({
        res = token %in% allowed_tokens
      }, silent = TRUE)
      return(res)
    }
    basic_auth_backend = AuthBackendBearer$new(FUN = auth_fun)

As an alternative to requiring authentication for a single endpoint we can make it mandatory for all endpoints which start with certain pattern:

    auth_mw = AuthMiddleware$new(
      auth_backend = basic_auth_backend,
      routes = "/secure/",
      match = "partial",
      id = "auth_middleware"
    )
    app = Application$new(middleware = list(auth_mw))

For example:

    app$add_get("/hello0", function(req, res) {res$body = "OK"})
    app$add_get("/secure/hello1", function(req, res) {res$body = "OK"})
    app$add_get("/secure/hello2", function(req, res) {res$body = "OK"})

Request with valid token to `/secure/hello1`:

    headers = list("Authorization" = "Bearer super_secure_token_1")
    req = Request$new(
      path = "/secure/hello1",
      headers = headers
    )

    res = app$process_request(req)
    res$body
    #> [1] "OK"

Request with invalid token to `/secure/hello2`:

    headers = list("Authorization" = "Bearer abcd")
    req = Request$new(
      path = "/secure/hello2",
      headers = headers
    )

    res = app$process_request(req)
    res$body
    #> [1] "401 Invalid Token"

Request to endpoint which doesn’t require authorization: `/hello0`:

    req = Request$new(path = "/hello0")
    res = app$process_request(req)
    res$body
    #> [1] "OK"