Re-namespacing

Moving away from the DNS-driven namespacing toward more condensed names,
mostly because I don't like typing so much.

1 files changed, 240 insertions, 0 deletions

diff --git a/Que/Server.hs b/Que/Server.hs
new file mode 100644
index 0000000..841cbfa
--- /dev/null
+++ b/Que/Server.hs
@@ -0,0 +1,240 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE DeriveGeneric #-}
+
+-- | Interprocess communication
+--
+-- Prior art:
+-- - <https://github.com/jb55/httpipe>
+-- - <https://patchbay.pub>
+-- - <https://github.com/hargettp/courier>
+-- - sorta: <https://ngrok.com/> and <https://localtunnel.github.io/www/>
+--
+-- : exe que-server
+--
+-- : dep async
+-- : dep envy
+-- : dep protolude
+-- : dep scotty
+-- : dep stm
+-- : dep unagi-chan
+-- : dep unordered-containers
+module Que.Server
+  ( main
+  )
+where
+
+import           Alpha                   hiding ( Text
+                                                , get
+                                                , gets
+                                                , modify
+                                                , poll
+                                                )
+import qualified Control.Concurrent.Go         as Go
+import qualified Control.Concurrent.STM        as STM
+import qualified Control.Exception             as Exception
+import           Control.Monad.Reader           ( MonadTrans )
+import qualified Data.ByteString.Builder.Extra as Builder
+import qualified Data.ByteString.Lazy          as BSL
+import           Data.HashMap.Lazy              ( HashMap )
+import qualified Data.HashMap.Lazy             as HashMap
+import qualified Data.Text.Encoding            as Encoding
+import           Data.Text.Lazy                 ( Text
+                                                , fromStrict
+                                                )
+import qualified Data.Text.Lazy.IO             as Text
+import qualified Network.HTTP.Types.Status     as Http
+import qualified Network.Wai                   as Wai
+import qualified Network.Wai.Handler.Warp      as Warp
+import           Network.Wai.Middleware.RequestLogger
+                                                ( logStdout )
+import qualified System.Envy                   as Envy
+import qualified System.Exit                   as Exit
+import qualified Web.Scotty.Trans              as Scotty
+
+main :: IO ()
+main = Exception.bracket startup shutdown <| uncurry Warp.run
+ where
+  startup = Envy.decodeEnv >>= \case
+    Left  e -> Exit.die e
+    Right c -> do
+      sync <- STM.newTVarIO initialAppState
+      let runActionToIO m = runReaderT (runApp m) sync
+      waiapp <- Scotty.scottyAppT runActionToIO routes
+      putText <| "port:" <> (show <| quePort c)
+      return (quePort c, waiapp)
+  shutdown :: a -> IO a
+  shutdown = pure . identity
+
+newtype App a = App
+  { runApp :: ReaderT (STM.TVar AppState) IO a
+  }
+  deriving (Applicative, Functor, Monad, MonadIO, MonadReader
+    (STM.TVar AppState))
+
+data AppState = AppState
+  { ques :: HashMap Namespace Quebase
+  }
+
+initialAppState :: AppState
+initialAppState = AppState { ques = mempty }
+
+data Config = Config
+  { quePort :: Warp.Port -- ^ QUE_PORT
+  } deriving (Generic, Show)
+
+instance Envy.DefConfig Config where
+  defConfig = Config 3000
+
+instance Envy.FromEnv Config
+
+routes :: Scotty.ScottyT Text App ()
+routes = do
+  Scotty.middleware logStdout
+
+  let quepath   = "^\\/([[:alnum:]_]+)\\/([[:alnum:]._/]*)$"
+  let namespace = "^\\/([[:alnum:]_]+)\\/?$" -- matches '/ns' and '/ns/' but not '/ns/path'
+
+  -- | GET /index.html
+  Scotty.get (Scotty.literal "/index.html") <| Scotty.redirect "/_/index"
+  Scotty.get (Scotty.literal "/") <| Scotty.redirect "/_/index"
+
+  -- | GET /_/dash
+  Scotty.get (Scotty.literal "/_/dash") <| do
+    authkey  <- fromMaybe "" </ Scotty.header "Authorization"
+    adminkey <- liftIO <| lchomp </ Text.readFile "/run/keys/que-admin"
+    if authkey == adminkey
+      then do
+        d <- app <| gets ques
+        Scotty.json d
+      else do
+        Scotty.status Http.methodNotAllowed405
+        Scotty.text "not allowed"
+
+
+  -- | Namespace management
+  Scotty.matchAny (Scotty.regex namespace) <| do
+    Scotty.status Http.notImplemented501
+    Scotty.text "namespace management coming soon"
+
+  -- | GET que
+  --
+  -- Receive a value from a que. Blocks until a value is received,
+  -- then returns. If 'poll=true', then stream data from the Que to the
+  -- client.
+  Scotty.get (Scotty.regex quepath) <| do
+    (ns, qp) <- extract
+    app . modify <| upsertNamespace ns
+    q    <- app <| que ns qp
+    poll <- Scotty.param "poll" !: (pure . const False)
+    guardNs ns ["pub", "_"]
+    case poll of
+      True -> Scotty.stream $ streamQue q
+      _    -> do
+        r <- liftIO <| Go.read q
+        Scotty.html <| fromStrict <| Encoding.decodeUtf8 r
+
+  -- | POST que
+  --
+  -- Put a value on a que. Returns immediately.
+  Scotty.post (Scotty.regex quepath) <| do
+    authkey  <- fromMaybe "" </ Scotty.header "Authorization"
+    adminkey <- liftIO <| lchomp </ Text.readFile "/run/keys/que-admin"
+    (ns, qp) <- extract
+    -- Only allow my IP or localhost to publish to '_' namespace
+    when ("_" == ns && authkey /= adminkey)
+      <| Scotty.status Http.methodNotAllowed405
+      >> Scotty.text "not allowed: _ is a reserved namespace"
+      >> Scotty.finish
+    guardNs ns ["pub", "_"]
+    -- passed all auth checks
+    app . modify <| upsertNamespace ns
+    q     <- app <| que ns qp
+    qdata <- Scotty.body
+    _     <- liftIO <| Go.write q <| BSL.toStrict qdata
+    return ()
+
+-- | Given `guardNs ns whitelist`, if `ns` is not in the `whitelist`
+-- list, return a 405 error.
+guardNs :: Text -> [Text] -> Scotty.ActionT Text App ()
+guardNs ns whitelist = when (not <| ns `elem` whitelist) <| do
+  Scotty.status Http.methodNotAllowed405
+  Scotty.text
+    <| "not allowed: use 'pub' namespace or signup to protect '"
+    <> ns
+    <> "' at https://que.run"
+  Scotty.finish
+
+-- | recover from a scotty-thrown exception.
+(!:)
+  :: Scotty.ActionT Text App a -- ^ action that might throw
+  -> (Text -> Scotty.ActionT Text App a) -- ^ a function providing a default response instead
+  -> Scotty.ActionT Text App a
+(!:) = Scotty.rescue
+
+-- | Forever write the data from 'Que' to 'Wai.StreamingBody'.
+streamQue :: Que -> Wai.StreamingBody
+streamQue q write _ = Go.mult q >>= loop
+ where
+  loop c =
+    Go.tap c
+      >>= (write . Builder.byteStringInsert)
+      >>  (write <| Builder.byteStringInsert "\n")
+      >>  loop c
+
+-- | Gets the thing from the Hashmap. Call's 'error' if key doesn't exist.
+grab :: (Eq k, Hashable k) => k -> HashMap k v -> v
+grab = flip (HashMap.!)
+
+-- | Inserts the namespace in 'AppState' if it doesn't exist.
+upsertNamespace :: Namespace -> AppState -> AppState
+upsertNamespace ns as = if HashMap.member ns (ques as)
+  then as
+  else as { ques = HashMap.insert ns mempty (ques as) }
+
+-- | Inserts the que at the proper 'Namespace' and 'Quepath'.
+insertQue :: Namespace -> Quepath -> Que -> AppState -> AppState
+insertQue ns qp q as = as { ques = newQues }
+ where
+  newQues  = HashMap.insert ns newQbase (ques as)
+  newQbase = HashMap.insert qp q <| grab ns <| ques as
+
+extract :: Scotty.ActionT Text App (Namespace, Quepath)
+extract = do
+  ns   <- Scotty.param "1"
+  path <- Scotty.param "2"
+  return (ns, path)
+
+-- | A synonym for 'lift' in order to be explicit about when we are
+-- operating at the 'App' layer.
+app :: MonadTrans t => App a -> t App a
+app = lift
+
+-- | Get something from the app state
+gets :: (AppState -> b) -> App b
+gets f = ask >>= liftIO . STM.readTVarIO >>= return . f
+
+-- | Apply a function to the app state
+modify :: (AppState -> AppState) -> App ()
+modify f = ask >>= liftIO . atomically . flip STM.modifyTVar' f
+
+type Namespace = Text -- ^ housing for a set of que paths
+type Que = Go.Channel Message -- ^ a que is just a channel of bytes
+type Quepath = Text -- ^ any path can serve as an identifier for a que
+type Message = ByteString -- ^ any opaque data
+type Quebase = HashMap Quepath Que -- ^ a collection of ques
+
+-- | Lookup or create a que
+que :: Namespace -> Quepath -> App Que
+que ns qp = do
+  _ques <- gets ques
+  let qbase     = grab ns _ques
+      queExists = HashMap.member qp qbase
+  if queExists
+    then return <| grab qp qbase
+    else do
+      c <- liftIO <| Go.chan 1
+      modify (insertQue ns qp c)
+      gets ques /> grab ns /> grab qp