From b0aa14ea3b12ab0559793bfb46df4625d7792bd4 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Sun, 28 Aug 2016 12:48:24 -0400
Subject: http: refuse to store object of unexpected size

---
 Tunables.hs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

(limited to 'Tunables.hs')

diff --git a/Tunables.hs b/Tunables.hs
index ce7aa6e..3fa700a 100644
--- a/Tunables.hs
+++ b/Tunables.hs
@@ -7,8 +7,10 @@
 
 module Tunables where
 
+import Types
 import Cost
 import qualified Crypto.Argon2 as Argon2
+import qualified Data.ByteString as B
 
 -- | To determine the tunables used for a key name the expensive hash of the
 -- name is calculated, using a particular configuration, and if the
@@ -38,6 +40,8 @@ data Tunables = Tunables
 	-- ^ a StorableObject is exactly this many bytes in size
 	-- (must be a multiple of AES block size 16, and cannot be smaller
 	-- than 256 bytes)
+	, shareOverhead :: Int
+	-- ^ Share encoding overhead as a multiple of the objectSize
 	, nameGenerationTunable :: NameGenerationTunable
 	, keyEncryptionKeyTunable :: KeyEncryptionKeyTunable
 	, encryptionTunable :: EncryptionTunable
@@ -82,7 +86,8 @@ data EncryptionTunable = UseAES256
 defaultTunables :: Tunables
 defaultTunables = Tunables
 	{ shareParams = ShareParams { totalObjects = 3, neededObjects = 2 }
-	, objectSize = 1024*64 -- 64 kb
+	, objectSize = 1024*32 -- 32 kb
+	, shareOverhead = 2
 	-- The nameGenerationHash was benchmarked at 661 seconds CPU time
 	-- on a 2 core Intel(R) Core(TM) i5-4210Y CPU @ 1.50GHz.
 	-- Since cost is measured per core, we double that.
@@ -114,7 +119,8 @@ defaultTunables = Tunables
 testModeTunables :: Tunables
 testModeTunables = Tunables
 	{ shareParams = ShareParams { totalObjects = 3, neededObjects = 2 }
-	, objectSize = 1024*64
+	, objectSize = 1024*32
+	, shareOverhead = 2
 	, nameGenerationTunable = NameGenerationTunable
 		{ nameGenerationHash = weakargon2 (CPUCost (Seconds (2*600)))
 		}
@@ -127,3 +133,10 @@ testModeTunables = Tunables
 	}
   where
 	weakargon2 c = UseArgon2 c Argon2.defaultHashOptions
+
+validObjectsize :: StorableObject -> Bool
+validObjectsize o = any (sz ==) knownsizes
+  where
+	sz = B.length (fromStorableObject o)
+	knownsizes = map (\t -> objectSize t * shareOverhead t)
+		(map snd knownTunings)
-- 
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