Server side rendered form delivered through channel csrf_token issue

I wonder whether this is tripping you up:

When posting a form with a host in its address, such as “//host.com/path” instead of only “/path”, Phoenix will include the host signature in the token and validate the token only if the accessed host is the same as the host in the token. This is to avoid tokens from leaking to third party applications. If this behaviour is problematic, you can generate a non-host specific token with Plug.CSRFProtection.get_csrf_token/0 and pass it to the form generator via the :csrf_token option.

And

If you are sending data to a full URI, such as //subdomain.host.com/path or //external.com/path , instead of a simple path such as /path , you may want to consider using get_csrf_token_for/1 , as that will encode the host in the CSRF token. Once received, Plug will only consider the CSRF token to be valid if the host encoded in the token is the same as the one in conn.host .

  <div>get_csrf_token: <%= "#{inspect Plug.CSRFProtection.get_csrf_token()}" %></div>
  <div>get_csrf_token_for: <%= "#{inspect Plug.CSRFProtection.get_csrf_token_for(Plug.Conn.request_url(@conn))}" %></div>
  <div>session _csrf_token: <%= "#{inspect Plug.Conn.get_session(@conn,"_csrf_token")}"  %></div>

get_csrf_token: "Aj0JAQsBOQ4BAD1BLh0yQVM9LzImNgAAJWc0oYhX2LJ+wDs1bvVvVg=="
get_csrf_token_for: "SFMyNTY.VXNyTUFWdGxSRDFQWlFobGd2ZFVPUT09bG9jYWxob3N0.gGQhCqEGKZ3qkXsHNwvB7AP4jt9T5TWle5OoUPi5GrQ"
session _csrf_token: "Hjj1dXQV3LwjYYAp1KyDpQ=="

_csrf_token is simply the “unmasked” CSRF token - your particular form element may have Phoenix looking for the token that includes the host.

Edit: Looking at the source code I’m guessing you can’t use the raw _csrf_token in the form element. In the absence of the host in the URL you have to use the masked value from Plug.CSRFProtection.get_csrf_token/0 otherwise use Plug.CSRFProtection.get_csrf_token_for/1 .

See also: Elixir, Phoenix, CSRF tokens

Thanks for the reply. Yes, I tried sending a new CSRF. i think I need to do some more research and see exactly when and where it is validated and see what is’nt reconciling. Drab looks cool, but i think I’m gonna wait and see how awesome LiveView is