feat(sasl): add negotiate function

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/stream.ml b/lib/stream.ml
index e3ed62f..ff3b939 100644
--- a/lib/stream.ml
+++ b/lib/stream.ml
@@ -1,3 +1,6 @@
+open Lwt.Syntax
+open Lwt.Infix
+
 exception ClosedStream
 
 type features = {
@@ -31,3 +34,16 @@ let parse_features (el : Xml.element) : features =
        parse_feature
        {mechanisms=[]; starttls=`None; unknown=[]}
        (List.filter_map find_left el.children)
+
+(** [negotiate domain stream] is a promise containing the features supported by the
+    XMPP server communicating with [stream].
+
+    This function should be called every time a stream needs to be reopened and stream
+    negotiation takes place.
+
+    Basically, it conforms to
+    {{: https://datatracker.ietf.org/doc/html/rfc6120#section-4.3 }}. *)
+let negotiate (domain : string) ((stream, push) : Portal.t) : features Lwt.t =
+  let* _id = Portal.header domain (stream, push)
+  in let+ features = Xml.get stream >|= parse_features
+     in features