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open Lwt.Syntax
type auth_mechanism = PLAIN [@@deriving show { with_path = false }]
type auth_config = {
jid : string;
password : string;
preferred_mechanisms : auth_mechanism list;
}
type sasl_error =
| NotAuthorized
| MalformedRequest
let read_sasl_error = function
| "not-authorized" -> NotAuthorized
| "malformed-request" -> MalformedRequest
| _ -> failwith "Unsupported SASL error returned by the server."
type sasl_auth = (string option, sasl_error * (string * string) option) result
let send_auth_stanza (stream, push) localpart pass mechanism =
let gen_auth = function
| PLAIN -> Base64.encode_exn ("\x00" ^ localpart ^ "\x00" ^ pass)
and parse_sasl_response (stanza : Markup.signal list) =
let open Markup in
let string_stanza = stanza |> of_list |> write_xml |> to_string in
let parse_additional_info = function
| `Text t :: _ -> Some (String.concat "" t)
| _ -> None
and parse_descriptive_text = function
| `Start_element ((_, "text"), [((_, "lang"), lang)]) :: `Text desc :: _ -> Some (lang, String.concat "" desc)
| `Start_element ((_, "text"), []) :: `Text desc :: _ -> Some ("en", String.concat "" desc)
| _ -> None
in
let parse_sasl_error = function
| `Start_element ((_, error), _) :: `End_element :: rest -> (read_sasl_error error, parse_descriptive_text rest)
| _ -> raise (Stream.InvalidStanza (stanza |> of_list |> write_xml |> to_string))
in match stanza with
| `Start_element ((_, "success"), _) :: rest -> Ok (parse_additional_info rest)
| `Start_element ((_, "failure"), _) :: rest -> Error (parse_sasl_error rest)
| _ -> raise (Stream.InvalidStanza string_stanza)
in let xmlns = "urn:ietf:params:xml:ns:xmpp-sasl" in
let stanza_list = [`Start_element
((xmlns, "auth"),
[(("", "xmlns"), xmlns);
(("", "mechanism"), show_auth_mechanism mechanism)]);
`Text [gen_auth mechanism];
`End_element]
in Some (Markup.of_list stanza_list) |> push;
let* response = Stream.get stream
in try Markup.to_list response |> parse_sasl_response |> Lwt.return
with exn -> Lwt.fail exn
let authenticate (portal : Portal.t) (config : auth_config) =
let {jid; password; _} = config
(* Probably not exactly compliant with https://xmpp.org/extensions/xep-0029.html,
but it's just for simplicity's sake in alpha. *)
in let localpart = match String.split_on_char '@' jid with
| [localpart; _domain] -> localpart
| _ -> failwith "Invalid JID"
in send_auth_stanza portal localpart password PLAIN
|
