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🐛 Fix / SAML nonce cookie #36

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Merged
docJerem merged 1 commit into from
Jun 2, 2026
Merged

🐛 Fix / SAML nonce cookie #36

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16 changes: 12 additions & 4 deletions lib/ex_saml/auth_handler.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,7 @@ defmodule ExSaml.AuthHandler do
%{
relay_state: relay_state,
session_id: session_id,
saml_nonce:
fetch_cookies(conn, encrypted: ~w(saml_nonce)).cookies["saml_nonce"] || UUID.uuid4(),
saml_nonce: resolve_saml_nonce(conn),
idp_id: idp_id,
user_token: get_session(conn, :user_token),
redirect_uri: get_session(conn, :redirect_uri),
Expand Down Expand Up @@ -99,8 +98,7 @@ defmodule ExSaml.AuthHandler do
%{
relay_state: relay_state,
session_id: session_id,
saml_nonce:
fetch_cookies(conn, encrypted: ~w(saml_nonce)).cookies["saml_nonce"] || UUID.uuid4(),
saml_nonce: resolve_saml_nonce(conn),
idp_id: idp_id,
target_url: target_url,
user_token: get_session(conn, :user_token),
Expand Down Expand Up @@ -180,4 +178,14 @@ defmodule ExSaml.AuthHandler do
# Logger.error("#{inspect error}")
# conn |> send_resp(500, "request_failed")
end

# Prefer a caller-assigned nonce so the SP can persist auxiliary state
# (e.g. redirect_uri) under the same key the IdP response will resolve to
# — `put_resp_cookie` does not populate `req_cookies`, so on the first
# round-trip the cookie fallback can't see what we just set.
defp resolve_saml_nonce(conn) do
conn.assigns[:saml_nonce] ||
fetch_cookies(conn, encrypted: ~w(saml_nonce)).cookies["saml_nonce"] ||
UUID.uuid4()
end
end
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