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Diffstat (limited to 'src/Lib.hs')
| -rw-r--r-- | src/Lib.hs | 313 |
1 files changed, 0 insertions, 313 deletions
diff --git a/src/Lib.hs b/src/Lib.hs deleted file mode 100644 index 5a48f3f..0000000 --- a/src/Lib.hs +++ /dev/null @@ -1,313 +0,0 @@ -{-# LANGUAGE TemplateHaskell #-} -{-# LANGUAGE OverloadedStrings #-} -{-# LANGUAGE RecordWildCards #-} -{-# LANGUAGE ScopedTypeVariables #-} -{-# LANGUAGE DeriveGeneric #-} -{-# LANGUAGE DeriveAnyClass #-} - -{-| -Description : Simple image hosting -Copyright : (c) Daniel, 2020 -License : BSD-3 -Maintainer : kingdread@gmx.de --} - -module Lib - ( -- * Data structures - App - , runApp - , Settings(..) - , defaultSettings - , Metadata(..) - , Seconds - -- * Entry points - , imgHostMain - , handleUpload - , handleCleanup - -- * Other functions - , checkAuthorization - , randomName - , validChars - , indexPage - , ask - , asks - , getImageData - , saveFile - ) where - - -import Data.ByteString.Char8 (pack) -import Control.Applicative -import Control.Monad -import Control.Monad.Reader hiding (ask, asks) -import Crypto.BCrypt -import Data.Aeson -import Data.Aeson.Types -import Data.FileEmbed -import Data.Maybe -import Data.Time.Clock.System -import Data.Traversable -import GHC.Generics -import Network.CGI -import System.Directory -import System.FilePath -import System.Random - -import qualified Control.Monad.Reader -import qualified Data.ByteString.Base64.Lazy as B64 -import qualified Data.ByteString.Lazy as BS -import qualified Data.HashMap.Strict as HM -import qualified Data.Text as T - --- | We are dealing with seconds when talking about durations, hence the type --- alias. -type Seconds = Integer - - --- | Metadata of a stored file. -data Metadata = Metadata { creator :: String - -- ^ Username of the creator. - , createdAt :: Integer - -- ^ Unix timestamp of the creation time. - , endOfLife :: Integer - -- ^ Unix timestamp of the expiration time. - } deriving (Show, Eq, Generic, FromJSON, ToJSON) - -isEternal :: Metadata -> Bool -isEternal Metadata{..} = createdAt == endOfLife - - --- | Application settings, should be read from a file at startup. -data Settings = Settings { outputDir :: FilePath - -- ^ Output directory for new images. - , defaultDuration :: Seconds - -- ^ Default lifetime of new images. - , nameLength :: Int - -- ^ Length (in characters) of the random identifier for images. - , users :: [(String, String)] - -- ^ A list of (user, password) pairs. - -- - -- Passwords are expected to be hashed using bcrypt. - } deriving (Show) - - -instance FromJSON Settings where - parseJSON = withObject "settings" $ \o -> do - outputDir <- o .:? "outputDir" .!= "img" - defaultDuration <- o .:? "defaultDuration" .!= 0 - nameLength <- o .:? "nameLength" .!= 20 - users <- (o .:? "users" .!= object []) >>= parseUserDict - return Settings{..} - - -parseUserDict :: Value -> Parser [(String, String)] -parseUserDict = - withObject "users" $ \o -> - for (HM.toList o) $ \(user, pw) -> do - password <- parseJSON pw - return (T.unpack user, password) - - -instance ToJSON Settings where - toJSON Settings{..} = object [ "outputDir" .= outputDir - , "defaultTimeout" .= defaultDuration - , "nameLength" .= nameLength - , "users" .= formatUsers users - ] - where - formatUsers :: [(String, String)] -> Object - formatUsers = HM.fromList . map (\(user, pw) -> (T.pack user, toJSON pw)) - - --- | Return the default settings. -defaultSettings :: Settings -defaultSettings = case fromJSON $ object [] of - Success a -> a - Error s -> error s - - --- | The application monad stack. --- --- This includes the CGI monad, IO and a reader to access the (global) --- application settings. -type App a = CGIT (ReaderT Settings IO) a - - --- | Run the given 'App' with the given 'Settings'. -runApp :: Settings -> App CGIResult -> IO () -runApp settings app = runReaderT (runCGI (handleErrors app)) settings - - --- | HTML source code of the index page. --- --- This is included at compile time from @src/index.html@. -indexPage :: String -indexPage = $(embedStringFile "src/index.html") - - --- | A lifted version of 'Control.Monad.Reader.ask'. --- --- Provides access to the 'Settings' instance in the 'App' monad stack. -ask :: App Settings -ask = lift Control.Monad.Reader.ask - - --- | A lifted version of 'Control.Monad.Reader.asks'. --- --- Provides access to the 'Settings' instance, but applies a function before --- returning the value: --- --- > directory <- asks outputDir -asks :: (Settings -> a) -> App a -asks f = fmap f ask - - -rightToMaybe :: Either a b -> Maybe b -rightToMaybe = either (const Nothing) Just - - -chooseRandom :: (RandomGen g) => [a] -> g -> (a, g) -chooseRandom inp gen = let (idx, nextGen) = randomR (0, length inp - 1) gen in - (inp !! idx, nextGen) - - --- | Valid characters for filename creation. -validChars :: String -validChars = ['a'..'z'] ++ ['A'..'Z'] - - --- | Creates a random filename. --- --- This uses the IO standard random generator to generate a name. -randomName :: App String -randomName = asks nameLength >>= \l -> - mapM (\_ -> liftIO $ getStdRandom (chooseRandom validChars)) [1..l] - - --- | Save the given file in the correct output directory. -saveFile :: BS.ByteString - -- ^ The file content to be saved, i.e. the image data. - -> String - -- ^ The file extension (including dot), or an empty string. - -> Seconds - -- ^ The duration until the file should expire, or 0. - -> String - -- ^ The user name of the user that saved the file. - -> App String - -- ^ Returns the file name that was used to save the file. -saveFile content extension duration username = do - filename <- (++ extension) <$> randomName - dir <- asks outputDir - let outputPath = dir </> filename - liftIO $ BS.writeFile outputPath content - currentTime <- liftIO getSystemTime - let eol = currentTime { systemSeconds = systemSeconds currentTime + fromInteger duration } - metadata = Metadata { creator = username - , createdAt = toInteger $ systemSeconds currentTime - , endOfLife = toInteger $ systemSeconds eol - } - liftIO $ BS.writeFile (outputPath ++ ".meta") (encode metadata) - return filename - - --- | Check the authorization data. -checkAuthorization :: [(String, String)] - -- ^ The (user, password) list. - -> Maybe String - -- ^ The given username. - -> Maybe String - -- ^ The given password. - -> Bool - -- ^ The authorization result. -checkAuthorization users (Just user) (Just password) = case lookup user users of - Just p -> validatePassword (pack p) (pack password) - Nothing -> False -checkAuthorization _ _ _ = False - - --- | Get the image data from the current request. --- --- This first checks if some raw content is given in the @imagecontent@ field --- (i.e. data from a pasted image), and afterwards checks @imagefile@ (i.e. the --- file selected in the file chooser). -getImageData :: App (Maybe BS.ByteString) -getImageData = do - rawData <- getInputFPS "imagecontent" - case rawData of - Just d | d /= "" -> return . rightToMaybe $ B64.decode d - _ -> getInputFPS "imagefile" - - -cleanupFile :: FilePath -> App () -cleanupFile fname = do - dir <- asks outputDir - currentTime <- systemSeconds <$> liftIO getSystemTime - content <- liftIO $ BS.readFile (dir </> fname) - case decode content :: (Maybe Metadata) of - Just metadata | isEternal metadata -> return () - Just metadata | endOfLife metadata < toInteger currentTime -> do - logCGI ("Deleting " ++ fname) - liftIO $ removeFile (dir </> fname) - liftIO $ removeFile (dir </> takeBaseName fname) - _ -> return () - - --- | Performs the cleanup by deleting expired images. -handleCleanup :: App CGIResult -handleCleanup = do - dir <- asks outputDir - files <- liftIO $ getDirectoryContents dir - let metaFiles = filter ((== ".meta") . takeExtension) files - forM_ metaFiles cleanupFile - output "Cleaning up" - - --- | Performs a file upload. -handleUpload :: App CGIResult -handleUpload = do - users <- asks users - outdir <- asks outputDir - user <- getInput "username" - password <- getInput "password" - let authorized = checkAuthorization users user password - if authorized then do - filecontent <- getImageData - filename <- getInputFilename "imagefile" - duration :: Maybe Integer <- readInput "duration" - let finfo = (,,) <$> filecontent <*> (filename <|> Just "") <*> duration - case finfo of - Just (content, name, dur) -> do - savedFileName <- saveFile content (takeExtension name) dur (fromJust user) - redirect $ outdir </> savedFileName - Nothing -> do - setStatus 400 "Missing data" - output "Invalid request" - else do - setStatus 401 "Unauthorized" - output "Invalid credentials" - --- | Main entry point of the application. --- --- Depending on the given parameters, this either dispatches to --- 'handleCleanup', 'handleUpload' or just returns the 'indexPage'. -imgHostMain :: App CGIResult -imgHostMain = dispatch [ (doCleanup, handleCleanup) - , (doUpload, handleUpload) - , (doDefault, output indexPage) - ] - where - dispatch :: [(App Bool, App CGIResult)] -> App CGIResult - dispatch ((c, a):as) = do - take_that <- c - if take_that then a - else dispatch as - dispatch [] = do - setStatus 500 "Internal Server Error" - output "No dispatch could be done :(" - - doCleanup :: App Bool - doCleanup = isJust <$> getInput "cleanup" - doUpload :: App Bool - doUpload = ("POST" ==) <$> requestMethod - doDefault :: App Bool - doDefault = return True |