memory DOS prevention

Prevent DOS of user side by limiting the size of the BackLog that
is maintained. This should not cause problems in even high latency
environments, and should prevent memory use > 16 mb.

The developer side does not keep much data, other than a list of the
Hashes of things it has recently sent, so is not susceptable to memory
DOS.

This commit was sponsored by Brock Spratlen on Patreon.

1 files changed, 8 insertions, 0 deletions

diff --git a/Log.hs b/Log.hs
index 90f1b53..8690f27 100644
--- a/Log.hs
+++ b/Log.hs
@@ -4,6 +4,7 @@ module Log where
 
 import Types
 import Hash
+import Memory
 
 import GHC.Generics (Generic)
 import Data.Aeson
@@ -28,6 +29,9 @@ data ActivityLog = ActivityLog
 	}
 	deriving (Show, Generic)
 
+instance DataSize ActivityLog where
+	dataSize l = dataSize (loggedActivity l) + dataSize (loggedHash l) + 2
+
 instance ToJSON (ActivityLog)
 instance FromJSON (ActivityLog)
 
@@ -36,6 +40,10 @@ data SomeActivity
 	| ActivityEntered (Activity Entered)
 	deriving (Show, Generic)
 
+instance DataSize SomeActivity where
+	dataSize (ActivitySeen a) = dataSize a
+	dataSize (ActivityEntered a) = dataSize a
+
 instance ToJSON SomeActivity where
 	toJSON = genericToJSON sumOptions
 	toEncoding = genericToEncoding sumOptions