1 files changed, 18 insertions, 0 deletions
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 48b903374d..0b464834ce 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -348,6 +348,24 @@ class IncompatibleRoomVersionError(SynapseError):
         )
 
 
+class RequestSendFailed(RuntimeError):
+    """Sending a HTTP request over federation failed due to not being able to
+    talk to the remote server for some reason.
+
+    This exception is used to differentiate "expected" errors that arise due to
+    networking (e.g. DNS failures, connection timeouts etc), versus unexpected
+    errors (like programming errors).
+    """
+    def __init__(self, inner_exception, can_retry):
+        super(RequestSendFailed, self).__init__(
+            "Failed to send request: %s: %s" % (
+                type(inner_exception).__name__, inner_exception,
+            )
+        )
+        self.inner_exception = inner_exception
+        self.can_retry = can_retry
+
+
 def cs_error(msg, code=Codes.UNKNOWN, **kwargs):
     """ Utility method for constructing an error response for client-server
     interactions.