add --download mode

Nice, was able to reuse all the protocol stuff from Role.Developer for
this.

This commit was sponsored by Fernando Jimenez on Patreon.

1 files changed, 12 insertions, 11 deletions

diff --git a/SessionID.hs b/SessionID.hs
index 3827e1d..d643a28 100644
--- a/SessionID.hs
+++ b/SessionID.hs
@@ -11,13 +11,13 @@ module SessionID (
 import Serialization
 
 import System.FilePath
-import Data.Text
 import System.IO
 import System.Directory
 import Network.Wai.Handler.Warp (Port)
 import Network.WebSockets hiding (Message)
 import qualified Data.Aeson
 import Data.Maybe
+import Data.List
 import Data.UUID
 import Data.UUID.V4
 
@@ -31,21 +31,22 @@ instance FromJSON SessionID
 
 instance WebSocketsData SessionID where
 	-- fromDataMessage = fromLazyByteString . fromDataMessage
-	fromLazyByteString = fromMaybe (error "bad SessionID") . Data.Aeson.decode
+	fromLazyByteString b =
+		-- Down't trust a legal SessionID to be deserialized;
+		-- use smart constructor to verify it's legal.
+		let SessionID unverified = fromMaybe (error "bad SessionID serialization") (Data.Aeson.decode b)
+		in fromMaybe (error "illegal SessionID") (mkSessionID unverified)
 	toLazyByteString = Data.Aeson.encode
 
 -- | Smart constructor that enforces legal SessionID contents.
 --
--- The passed Text can either be the bare SessionID, or it can be an URL
+-- The passed String can either be the bare SessionID, or it can be an URL
 -- which ends with the SessionID.
-mkSessionID :: Text -> Maybe SessionID
-mkSessionID t = 
-	let s = unpack t
-	in if "http" `isPrefixOf` t
-		then Just $ SessionID $ takeFileName s
-		else if takeFileName s == s
-			then Just $ SessionID s
-			else Nothing
+mkSessionID :: String -> Maybe SessionID
+mkSessionID s
+	| "http" `isPrefixOf` s = Just $ SessionID $ takeFileName s
+	| takeFileName s == s = Just $ SessionID s
+	| otherwise = Nothing
 
 sessionLogFile :: FilePath -> SessionID -> FilePath
 sessionLogFile dir (SessionID f) = dir </> "debug-me." ++ f ++ ".log"