made reactToMessage robust against unsolicited responses.

1 files changed, 16 insertions, 8 deletions

diff --git a/SybilLimit.hs b/SybilLimit.hs
index 8d053f9..9befb31 100644
--- a/SybilLimit.hs
+++ b/SybilLimit.hs
@@ -161,16 +161,24 @@ reactToMessage w (srcId, msg@(RegistrationResponse {})) me =
         where goodTail = Map.insert tail indexes
                                     $ sybVerifiedTails p
               indexes = fromMaybe [] $ Map.lookup tail $ sybPendingTails p
-    icheck = pendingChecks me0 Map.! rrSuspect msg
-    (me',sybils) = if Map.null (sybPendingTails icheck) then bcheck else (me0, [])
-        where bcheck = if Map.null (sybVerifiedTails icheck)
+    (me',sybils) =
+            case Map.lookup (rrSuspect msg) $ pendingChecks me0 of
+              Nothing -> (me0,[])
+              Just icheck -> if Map.null (sybPendingTails icheck)
+                                then bcheck icheck
+                                else (me0, [])
+        where bcheck icheck
+                = if Map.null (sybVerifiedTails icheck)
                         then (me0, dishonest)
                         else balanceCheck
-              dishonest = [SybilCheck (rrSuspect msg) False]
-              indexes = fromMaybe [] $ Map.lookup tail $ sybVerifiedTails icheck
-              balanceCheck = second chk $ balanceCondition tail indexes me0
-                where chk = (:[]) . SybilCheck (rrSuspect msg)
-                      second f (x,y) = (x,f y)
+                where
+                  dishonest = [SybilCheck (rrSuspect msg) False]
+                  balanceCheck = second chk $ balanceCondition tail indexes me0
+                    where chk = (:[]) . SybilCheck (rrSuspect msg)
+                          second f (x,y) = (x,f y)
+                          indexes = fromMaybe []
+                                    . Map.lookup tail
+                                    $ sybVerifiedTails icheck
 
 reactToMessage w (srcId, msg@(RegistrationQuery {})) me =
     MessageReaction me [(srcId,resp)] []