Add support for MSC2732: olm fallback keys (#8312)

2 files changed, 24 insertions, 0 deletions

diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index dd40fd1299..611742ae72 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -496,6 +496,22 @@ class E2eKeysHandler:
             log_kv(
                 {"message": "Did not update one_time_keys", "reason": "no keys given"}
             )
+        fallback_keys = keys.get("org.matrix.msc2732.fallback_keys", None)
+        if fallback_keys and isinstance(fallback_keys, dict):
+            log_kv(
+                {
+                    "message": "Updating fallback_keys for device.",
+                    "user_id": user_id,
+                    "device_id": device_id,
+                }
+            )
+            await self.store.set_e2e_fallback_keys(user_id, device_id, fallback_keys)
+        elif fallback_keys:
+            log_kv({"message": "Did not update fallback_keys", "reason": "not a dict"})
+        else:
+            log_kv(
+                {"message": "Did not update fallback_keys", "reason": "no keys given"}
+            )
 
         # the device should have been registered already, but it may have been
         # deleted due to a race with a DELETE request. Or we may be using an
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index a998e6b7f6..dd1f90e359 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -201,6 +201,8 @@ class SyncResult:
         device_lists: List of user_ids whose devices have changed
         device_one_time_keys_count: Dict of algorithm to count for one time keys
             for this device
+        device_unused_fallback_key_types: List of key types that have an unused fallback
+            key
         groups: Group updates, if any
     """
 
@@ -213,6 +215,7 @@ class SyncResult:
     to_device = attr.ib(type=List[JsonDict])
     device_lists = attr.ib(type=DeviceLists)
     device_one_time_keys_count = attr.ib(type=JsonDict)
+    device_unused_fallback_key_types = attr.ib(type=List[str])
     groups = attr.ib(type=Optional[GroupsSyncResult])
 
     def __bool__(self) -> bool:
@@ -1014,10 +1017,14 @@ class SyncHandler:
         logger.debug("Fetching OTK data")
         device_id = sync_config.device_id
         one_time_key_counts = {}  # type: JsonDict
+        unused_fallback_key_types = []  # type: List[str]
         if device_id:
             one_time_key_counts = await self.store.count_e2e_one_time_keys(
                 user_id, device_id
             )
+            unused_fallback_key_types = await self.store.get_e2e_unused_fallback_key_types(
+                user_id, device_id
+            )
 
         logger.debug("Fetching group data")
         await self._generate_sync_entry_for_groups(sync_result_builder)
@@ -1041,6 +1048,7 @@ class SyncHandler:
             device_lists=device_lists,
             groups=sync_result_builder.groups,
             device_one_time_keys_count=one_time_key_counts,
+            device_unused_fallback_key_types=unused_fallback_key_types,
             next_batch=sync_result_builder.now_token,
         )