plugin XEP-0353, XEP-0234, jingle: WebRTC data channel signaling implementation: Implement XEP-0343: Signaling WebRTC Data Channels in Jingle. The current version of the XEP (0.3.1) has no implementation and contains some flaws. After discussing this on xsf@, Daniel (from Conversations) mentioned that they had a sprint with Larma (from Dino) to work on another version and provided me with this link: https://gist.github.com/iNPUTmice/6c56f3e948cca517c5fb129016d99e74 . I have used it for my implementation. This implementation reuses work done on Jingle A/V call (notably XEP-0176 and XEP-0167 plugins), with adaptations. When used, XEP-0234 will not handle the file itself as it normally does. This is because WebRTC has several implementations (browser for web interface, GStreamer for others), and file/data must be handled directly by the frontend. This is particularly important for web frontends, as the file is not sent from the backend but from the end-user's browser device. Among the changes, there are: - XEP-0343 implementation. - `file_send` bridge method now use serialised dict as output. - New `BaseTransportHandler.is_usable` method which get content data and returns a boolean (default to `True`) to tell if this transport can actually be used in this context (when we are initiator). Used in webRTC case to see if call data are available. - Support of `application` media type, and everything necessary to handle data channels. - Better confirmation message, with file name, size and description when available. - When file is accepted in preflight, it is specified in following `action_new` signal for actual file transfer. This way, frontend can avoid the display or 2 confirmation messages. - XEP-0166: when not specified, default `content` name is now its index number instead of a UUID. This follows the behaviour of browsers. - XEP-0353: better handling of events such as call taken by another device. - various other updates. rel 441

--- a/libervia/backend/plugins/plugin_xep_0166/__init__.py	Sat Apr 06 12:21:04 2024 +0200
+++ b/libervia/backend/plugins/plugin_xep_0166/__init__.py	Sat Apr 06 12:57:23 2024 +0200
@@ -534,7 +534,7 @@
                 f"No application registered for {namespace}"
             )
 
-    def get_content_data(self, content: dict) -> ContentData:
+    def get_content_data(self, content: dict, content_idx: int) -> ContentData:
         """"Retrieve application and its argument from content"""
         app_ns = content["app_ns"]
         try:
@@ -547,7 +547,7 @@
         try:
             content_name = content["name"]
         except KeyError:
-            content_name = content["name"] = str(uuid.uuid4())
+            content_name = content["name"] = str(content_idx)
         return ContentData(
             application,
             app_args,
@@ -611,15 +611,16 @@
 
         session_contents = session["contents"]
 
-        for content in contents:
+        for content_idx, content in enumerate(contents):
             # we get the application plugin
-            content_data = self.get_content_data(content)
+            content_data = self.get_content_data(content, content_idx)
 
             # and the transport plugin
             transport_type = content.get("transport_type", XEP_0166.TRANSPORT_STREAMING)
-            try:
-                transport = self._type_transports[transport_type][0]
-            except IndexError:
+            for transport in self._type_transports[transport_type]:
+                if transport.handler.is_usable(client, content_data):
+                    break
+            else:
                 raise exceptions.InternalError(
                     "No transport registered for {}".format(transport_type)
                 )