From eb6636380f7ffca97b32e850563487e192876dd8 Mon Sep 17 00:00:00 2001
From: Quentin Gliech <quenting@element.io>
Date: Thu, 12 Sep 2024 15:07:33 +0200
Subject: [PATCH] Parse the io.element.msc4190 flag on AS registrations

---
 synapse/appservice/__init__.py |  2 ++
 synapse/config/appservice.py   | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/synapse/appservice/__init__.py b/synapse/appservice/__init__.py
index a96cdbf1e7..6ee5240c4e 100644
--- a/synapse/appservice/__init__.py
+++ b/synapse/appservice/__init__.py
@@ -87,6 +87,7 @@ class ApplicationService:
         ip_range_whitelist: Optional[IPSet] = None,
         supports_ephemeral: bool = False,
         msc3202_transaction_extensions: bool = False,
+        msc4190_device_management: bool = False,
     ):
         self.token = token
         self.url = (
@@ -100,6 +101,7 @@ class ApplicationService:
         self.ip_range_whitelist = ip_range_whitelist
         self.supports_ephemeral = supports_ephemeral
         self.msc3202_transaction_extensions = msc3202_transaction_extensions
+        self.msc4190_device_management = msc4190_device_management
 
         if "|" in self.id:
             raise Exception("application service ID cannot contain '|' character")
diff --git a/synapse/config/appservice.py b/synapse/config/appservice.py
index 6ff00e1ff8..8a38229dd2 100644
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -183,6 +183,18 @@ def _load_appservice(
             "The `org.matrix.msc3202` option should be true or false if specified."
         )
 
+    # Opt-in flag for the MSC4190 behaviours.
+    # When enabled, the following C-S API endpoints change:
+    # - POST /register does not return an access token
+    # - PUT /devices/{device_id} creates a new device if one does not exist
+    # - DELETE /devices/{device_id} no longer requires UIA
+    # - POST /delete_devices/{device_id} no longer requires UIA
+    msc4190_enabled = as_info.get("io.element.msc4190", False)
+    if not isinstance(msc4190_enabled, bool):
+        raise ValueError(
+            "The `io.element.msc4190` option should be true or false if specified."
+        )
+
     return ApplicationService(
         token=as_info["as_token"],
         url=as_info["url"],
@@ -195,4 +207,5 @@ def _load_appservice(
         ip_range_whitelist=ip_range_whitelist,
         supports_ephemeral=supports_ephemeral,
         msc3202_transaction_extensions=msc3202_transaction_extensions,
+        msc4190_device_management=msc4190_enabled,
     )