Fix private file path checks

flake.nix

@@ -83,6 +83,10 @@
       rec {
         packages = {
           inherit nix-serve-ng lix-serve-ng;
+          private = pkgs.runCommand "private" { } ''
+            mkdir $out
+            touch $out/.private
+          '';
           default = nix-serve-ng;
         };
 

src/Main.hs

@@ -12,6 +12,7 @@ import Control.Monad.IO.Class (liftIO)
 import Data.ByteString (ByteString)
 import Data.CharSet.ByteSet (ByteSet(..))
 import Data.Function ((&))
+import Data.Word (Word8)
 import Network.Socket (SockAddr(..))
 import Network.Wai (Application)
 import Nix (NoSuchPath(..), PathInfo(..))
@@ -57,6 +58,20 @@ validHashPartBytes =
         <>  [ 0x76 .. 0x7A ]  -- vwxyz
         )
 
+type HostAddressTuple = (Word8, Word8, Word8, Word8)
+
+isAllowed :: Socket.HostAddress -> Bool
+isAllowed host = any (uncurry (ipMatches $ Socket.hostAddressToTuple host)) allowedIPs
+    where
+        allowedIPs :: [(HostAddressTuple, HostAddressTuple)]
+        allowedIPs = [
+                ((127,0,0,1),    (127,0,0,1)),
+                ((10,0,0,1),     (10,255,255,254)),
+                ((192,168,72,1), (192,168,79,254))
+            ]
+
+        ipMatches ip a b = ip >= a && ip <= b
+
 validHashPart :: ByteString -> Bool
 validHashPart hash = ByteString.all (`ByteSet.member` validHashPartBytes) hash
 
@@ -253,22 +268,21 @@ makeApplication ApplicationOptions{..} request respond = do
 
                     done response
 
-                isPrivate <- not <$> liftIO (Directory.doesPathExist (ByteString.Char8.unpack storePath ++ "/.private"))
+                let privateFilePath = ByteString.Char8.unpack storePath ++ "/.private"
+                isPrivate <- liftIO $ Directory.doesPathExist privateFilePath
+
                 let sockAddr = Wai.remoteHost request
                 hostAddr  <- case sockAddr of
                     SockAddrInet _ host -> return host
                     _ -> return $ Socket.tupleToHostAddress (255, 255, 255, 255)
 
-                let isInternalClient = hostAddr >= Socket.tupleToHostAddress (10, 0, 0, 0) && hostAddr < Socket.tupleToHostAddress (11, 0, 0, 0)
+                traceM $ show (Socket.hostAddressToTuple hostAddr, isAllowed hostAddr)
+                traceM $ show (privateFilePath, isPrivate)
 
-                traceM $ show (ByteString.Char8.unpack storePath, "private", isPrivate,
-                    "host", hostAddr,
-                    "isInternalClient", isInternalClient
-                    )
-                Monad.unless (isInternalClient || not isPrivate) do
+                Monad.when (isPrivate && (not $ isAllowed hostAddr)) do
                     let headers = [ ("Content-Type", "text/plain") ]
 
-                    let builder = "Forbbiden.\n"
+                    let builder = "Forbidden.\n"
 
                     let response =
                             Wai.responseBuilder