--- a/mod_auth_oauth_external/mod_auth_oauth_external.lua	Thu Mar 16 12:45:22 2023 +0100
+++ b/mod_auth_oauth_external/mod_auth_oauth_external.lua	Thu Mar 16 12:45:52 2023 +0100
@@ -6,12 +6,14 @@
 -- TODO -- local issuer_identity = module:get_option_string("oauth_external_issuer");
 local oidc_discovery_url = module:get_option_string("oauth_external_discovery_url")
 local validation_endpoint = module:get_option_string("oauth_external_validation_endpoint");
+local token_endpoint = module:get_option_string("oauth_external_token_endpoint");
 
 local username_field = module:get_option_string("oauth_external_username_field", "preferred_username");
+local allow_plain = module:get_option_boolean("oauth_external_resource_owner_password", true);
 
 -- XXX Hold up, does whatever done here even need any of these things? Are we
 -- the OAuth client? Is the XMPP client the OAuth client? What are we???
--- TODO -- local client_id = module:get_option_string("oauth_external_client_id");
+local client_id = module:get_option_string("oauth_external_client_id");
 -- TODO -- local client_secret = module:get_option_string("oauth_external_client_secret");
 
 --[[ More or less required endpoints
@@ -29,6 +31,46 @@
 	local profile = {};
 	profile.http_client = http.default; -- TODO configurable
 	local extra = { oidc_discovery_url = oidc_discovery_url };
+	if token_endpoint and allow_plain then
+		local map_username = function (username, _realm) return username; end; --jid.join; -- TODO configurable
+		function profile:plain_test(username, password, realm)
+			local tok, err = async.wait_for(self.profile.http_client:request(token_endpoint, {
+				headers = { ["Content-Type"] = "application/x-www-form-urlencoded; charset=utf-8"; ["Accept"] = "application/json" };
+				body = http.formencode({
+					grant_type = "password";
+					client_id = client_id;
+					username = map_username(username, realm);
+					password = password;
+					scope = "openid";
+				});
+			}))
+			if err or not (tok.code >= 200 and tok.code < 300) then
+				return false, nil;
+			end
+			local token_resp = json.decode(tok.body);
+			if not token_resp or string.lower(token_resp.token_type or "") ~= "bearer" then
+				return false, nil;
+			end
+			local ret, err = async.wait_for(self.profile.http_client:request(validation_endpoint,
+				{ headers = { ["Authorization"] = "Bearer " .. token_resp.access_token; ["Accept"] = "application/json" } }));
+			if err then
+				return false, nil;
+			end
+			if not (ret.code >= 200 and ret.code < 300) then
+				return false, nil;
+			end
+			local response = json.decode(ret.body);
+			if type(response) ~= "table" or (response[username_field]) ~= username then
+				return false, nil, nil;
+			end
+			if response.jid then
+				self.username, self.realm, self.resource = jid.prepped_split(response.jid, true);
+			end
+			self.role = response.role;
+			self.token_info = response;
+			return true, true;
+		end
+	end
 	function profile:oauthbearer(token)
 		if token == "" then
 			return false, nil, extra;