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Giraffe.Antiforgery
// This file is a consolidated version of Giraffe.Antiforgery from
// https://github.com/pimbrouwers/Giraffe.Antiforgery, and is Copyright Pim Brouwers, licensed
// under Apache 2.0, which is included at the end of this file.
//
// I include it here because at the time of writing the blog post carpenoctem.dev/blog/fsharp-giraffe-auth-identity/ the
// package was out of date. It has slight modifications to comments.
module Giraffe.Antiforgery
open Microsoft.AspNetCore.Http
open Microsoft.AspNetCore.Antiforgery
open Giraffe
open Giraffe.ViewEngine
// This function calls `GetAndStoreTokens` to generate a anti-csrf token, create a cookie and store it in ctx.
// However, you probably won't use it too often -- favor csrfHtmlView instead
let csrfTokenizer (handler : AntiforgeryTokenSet -> HttpHandler) : HttpHandler =
fun (next: HttpFunc) (ctx : HttpContext) ->
let antiFrg = ctx.GetService<IAntiforgery>()
(antiFrg.GetAndStoreTokens ctx |> handler) next ctx
// Injects a newly generated CSRF token into a Giraffe.GiraffeViewEngine.XmlNode
// in order to use it, modify our view functions with an additional `token` parameter (it should be the last parameter)
// and then call csrfHtmlView instead of htmlView
let csrfHtmlView (view : AntiforgeryTokenSet -> XmlNode) : HttpHandler =
let handler token : HttpHandler =
fun (next: HttpFunc) (ctx : HttpContext) ->
htmlView (view token) next ctx
csrfTokenizer handler
// Checks the presence and validity of CSRF token and calls invalidTokenHandler on failure
// GET, HEAD, OPTIONS & TRACE always validate as true
let requiresCsrfToken (invalidTokenHandler : HttpHandler) : HttpHandler =
fun (next: HttpFunc) (ctx : HttpContext) ->
let antiFrg = ctx.GetService<IAntiforgery>()
(match antiFrg.IsRequestValidAsync(ctx) |> Async.AwaitTask |> Async.RunSynchronously with
| true -> next
| false -> invalidTokenHandler earlyReturn) ctx
let antiforgeryInput (token : AntiforgeryTokenSet) =
input [
_type "hidden"
_name token.FormFieldName
_value token.RequestToken
]
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