635 lines
20 KiB
Haskell
635 lines
20 KiB
Haskell
{- Url downloading.
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-
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- Copyright 2011-2019 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE RankNTypes #-}
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{-# LANGUAGE FlexibleContexts #-}
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module Utility.Url (
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newManager,
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URLString,
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UserAgent,
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Scheme,
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mkScheme,
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allowedScheme,
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UrlDownloader(..),
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NonHttpUrlDownloader(..),
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UrlOptions(..),
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defUrlOptions,
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mkUrlOptions,
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check,
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checkBoth,
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exists,
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UrlInfo(..),
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getUrlInfo,
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assumeUrlExists,
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download,
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downloadQuiet,
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downloadConduit,
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sinkResponseFile,
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downloadPartial,
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parseURIRelaxed,
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matchStatusCodeException,
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matchHttpExceptionContent,
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) where
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import Common
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import Utility.Metered
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import Utility.HttpManagerRestricted
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import Utility.IPAddress
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import Network.URI
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import Network.HTTP.Types
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import qualified Network.Connection as NC
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import qualified Data.CaseInsensitive as CI
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import qualified Data.ByteString as B
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import qualified Data.ByteString.UTF8 as B8
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import qualified Data.ByteString.Lazy as L
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import qualified Data.Set as S
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import Control.Exception (throwIO)
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import Control.Monad.Trans.Resource
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import Network.HTTP.Conduit
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import Network.HTTP.Client
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import Network.HTTP.Simple (getResponseHeader)
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import Network.Socket
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import Network.BSD (getProtocolNumber)
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import Data.Either
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import Data.Conduit
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import Text.Read
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import System.Log.Logger
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type URLString = String
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type Headers = [String]
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type UserAgent = String
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newtype Scheme = Scheme (CI.CI String)
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deriving (Eq, Ord)
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mkScheme :: String -> Scheme
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mkScheme = Scheme . CI.mk
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fromScheme :: Scheme -> String
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fromScheme (Scheme s) = CI.original s
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data UrlOptions = UrlOptions
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{ userAgent :: Maybe UserAgent
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, reqHeaders :: Headers
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, urlDownloader :: UrlDownloader
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, applyRequest :: Request -> Request
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, httpManager :: Manager
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, allowedSchemes :: S.Set Scheme
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}
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data UrlDownloader
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= DownloadWithConduit NonHttpUrlDownloader
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| DownloadWithCurl [CommandParam]
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data NonHttpUrlDownloader
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= DownloadWithCurlRestricted Restriction
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defUrlOptions :: IO UrlOptions
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defUrlOptions = UrlOptions
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<$> pure Nothing
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<*> pure []
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<*> pure (DownloadWithConduit (DownloadWithCurlRestricted mempty))
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<*> pure id
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<*> newManager tlsManagerSettings
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<*> pure (S.fromList $ map mkScheme ["http", "https", "ftp"])
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mkUrlOptions :: Maybe UserAgent -> Headers -> UrlDownloader -> Manager -> S.Set Scheme -> UrlOptions
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mkUrlOptions defuseragent reqheaders urldownloader manager =
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UrlOptions useragent reqheaders urldownloader applyrequest manager
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where
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applyrequest = \r -> r { requestHeaders = requestHeaders r ++ addedheaders }
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addedheaders = uaheader ++ otherheaders
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useragent = maybe defuseragent (Just . B8.toString . snd)
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(headMaybe uafromheaders)
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uaheader = case useragent of
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Nothing -> []
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Just ua -> [(hUserAgent, B8.fromString ua)]
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(uafromheaders, otherheaders) = partition (\(h, _) -> h == hUserAgent)
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(map toheader reqheaders)
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toheader s =
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let (h, v) = separate (== ':') s
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h' = CI.mk (B8.fromString h)
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in case v of
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(' ':v') -> (h', B8.fromString v')
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_ -> (h', B8.fromString v)
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curlParams :: UrlOptions -> [CommandParam] -> [CommandParam]
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curlParams uo ps = ps ++ uaparams ++ headerparams ++ addedparams ++ schemeparams
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where
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uaparams = case userAgent uo of
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Nothing -> []
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Just ua -> [Param "--user-agent", Param ua]
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headerparams = concatMap (\h -> [Param "-H", Param h]) (reqHeaders uo)
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addedparams = case urlDownloader uo of
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DownloadWithConduit _ -> []
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DownloadWithCurl l -> l
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schemeparams =
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[ Param "--proto"
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, Param $ intercalate "," ("-all" : schemelist)
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]
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schemelist = map fromScheme $ S.toList $ allowedSchemes uo
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checkPolicy :: UrlOptions -> URI -> a -> (String -> IO b) -> IO a -> IO a
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checkPolicy uo u onerr displayerror a
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| allowedScheme uo u = a
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| otherwise = do
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void $ displayerror $
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"Configuration does not allow accessing " ++ show u
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return onerr
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unsupportedUrlScheme :: URI -> (String -> IO a) -> IO a
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unsupportedUrlScheme u displayerror =
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displayerror $ "Unsupported url scheme " ++ show u
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warnError :: String -> IO ()
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warnError msg = do
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hPutStrLn stderr msg
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hFlush stderr
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allowedScheme :: UrlOptions -> URI -> Bool
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allowedScheme uo u = uscheme `S.member` allowedSchemes uo
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where
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uscheme = mkScheme $ takeWhile (/=':') (uriScheme u)
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{- Checks that an url exists and could be successfully downloaded,
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- also checking that its size, if available, matches a specified size. -}
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checkBoth :: URLString -> Maybe Integer -> UrlOptions -> IO Bool
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checkBoth url expected_size uo = do
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v <- check url expected_size uo
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return (fst v && snd v)
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check :: URLString -> Maybe Integer -> UrlOptions -> IO (Bool, Bool)
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check url expected_size uo = go <$> getUrlInfo url uo
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where
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go (UrlInfo False _ _) = (False, False)
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go (UrlInfo True Nothing _) = (True, True)
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go (UrlInfo True s _) = case expected_size of
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Just _ -> (True, expected_size == s)
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Nothing -> (True, True)
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exists :: URLString -> UrlOptions -> IO Bool
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exists url uo = urlExists <$> getUrlInfo url uo
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data UrlInfo = UrlInfo
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{ urlExists :: Bool
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, urlSize :: Maybe Integer
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, urlSuggestedFile :: Maybe FilePath
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}
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deriving (Show)
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assumeUrlExists :: UrlInfo
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assumeUrlExists = UrlInfo True Nothing Nothing
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{- Checks that an url exists and could be successfully downloaded,
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- also returning its size and suggested filename if available. -}
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getUrlInfo :: URLString -> UrlOptions -> IO UrlInfo
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getUrlInfo url uo = case parseURIRelaxed url of
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Just u -> checkPolicy uo u dne warnError $
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case (urlDownloader uo, parseUrlRequest (show u)) of
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(DownloadWithConduit (DownloadWithCurlRestricted r), Just req) -> catchJust
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-- When http redirects to a protocol which
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-- conduit does not support, it will throw
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-- a StatusCodeException with found302
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-- and a Response with the redir Location.
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(matchStatusCodeException (== found302))
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(existsconduit req)
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(followredir r)
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`catchNonAsync` (const $ return dne)
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(DownloadWithConduit (DownloadWithCurlRestricted r), Nothing)
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| isfileurl u -> existsfile u
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| isftpurl u -> existscurlrestricted r u url ftpport
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`catchNonAsync` (const $ return dne)
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| otherwise -> do
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unsupportedUrlScheme u warnError
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return dne
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(DownloadWithCurl _, _)
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| isfileurl u -> existsfile u
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| otherwise -> existscurl u (basecurlparams url)
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Nothing -> return dne
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where
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dne = UrlInfo False Nothing Nothing
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found sz f = return $ UrlInfo True sz f
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isfileurl u = uriScheme u == "file:"
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isftpurl u = uriScheme u == "ftp:"
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ftpport = 21
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basecurlparams u = curlParams uo $
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[ Param "-s"
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, Param "--head"
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, Param "-L", Param u
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, Param "-w", Param "%{http_code}"
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]
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extractlencurl s = case lastMaybe $ filter ("Content-Length:" `isPrefixOf`) (lines s) of
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Just l -> case lastMaybe $ words l of
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Just sz -> readish sz
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_ -> Nothing
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_ -> Nothing
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extractlen = readish . B8.toString
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<=< lookup hContentLength . responseHeaders
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extractfilename = contentDispositionFilename . B8.toString
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<=< lookup hContentDisposition . responseHeaders
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existsconduit req = do
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let req' = headRequest (applyRequest uo req)
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debugM "url" (show req')
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runResourceT $ do
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resp <- http req' (httpManager uo)
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-- forces processing the response while
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-- within the runResourceT
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liftIO $ if responseStatus resp == ok200
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then found
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(extractlen resp)
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(extractfilename resp)
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else return dne
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existscurl u curlparams = do
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output <- catchDefaultIO "" $
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readProcess "curl" $ toCommand curlparams
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let len = extractlencurl output
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let good = found len Nothing
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let isftp = or
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[ "ftp" `isInfixOf` uriScheme u
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-- Check to see if http redirected to ftp.
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, "Location: ftp://" `isInfixOf` output
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]
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case lastMaybe (lines output) of
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Just ('2':_:_) -> good
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-- don't try to parse ftp status codes; if curl
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-- got a length, it's good
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_ | isftp && isJust len -> good
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_ -> return dne
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existscurlrestricted r u url' defport = existscurl u
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=<< curlRestrictedParams r u defport (basecurlparams url')
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existsfile u = do
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let f = unEscapeString (uriPath u)
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s <- catchMaybeIO $ getFileStatus f
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case s of
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Just stat -> do
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sz <- getFileSize' f stat
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found (Just sz) Nothing
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Nothing -> return dne
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followredir r (HttpExceptionRequest _ (StatusCodeException resp _)) =
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case headMaybe $ map decodeBS $ getResponseHeader hLocation resp of
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Just url' -> case parseURIRelaxed url' of
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-- only follow http to ftp redirects;
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-- http to file redirect would not be secure,
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-- and http-conduit follows http to http.
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Just u' | isftpurl u' ->
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checkPolicy uo u' dne warnError $
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existscurlrestricted r u' url' ftpport
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_ -> return dne
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Nothing -> return dne
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followredir _ _ = return dne
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-- Parse eg: attachment; filename="fname.ext"
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-- per RFC 2616
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contentDispositionFilename :: String -> Maybe FilePath
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contentDispositionFilename s
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| "attachment; filename=\"" `isPrefixOf` s && "\"" `isSuffixOf` s =
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Just $ dropFromEnd 1 $ drop 1 $ dropWhile (/= '"') s
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| otherwise = Nothing
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headRequest :: Request -> Request
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headRequest r = r
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{ method = methodHead
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-- remove defaut Accept-Encoding header, to get actual,
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-- not gzip compressed size.
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, requestHeaders = (hAcceptEncoding, B.empty) :
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filter (\(h, _) -> h /= hAcceptEncoding)
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(requestHeaders r)
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}
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{- Download a perhaps large file, with auto-resume of incomplete downloads.
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-
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- Displays error message on stderr when download failed.
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-}
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download :: MeterUpdate -> URLString -> FilePath -> UrlOptions -> IO Bool
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download = download' False
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{- Avoids displaying any error message. -}
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downloadQuiet :: MeterUpdate -> URLString -> FilePath -> UrlOptions -> IO Bool
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downloadQuiet = download' True
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download' :: Bool -> MeterUpdate -> URLString -> FilePath -> UrlOptions -> IO Bool
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download' noerror meterupdate url file uo =
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catchJust matchHttpException go showhttpexception
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`catchNonAsync` (dlfailed . show)
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where
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go = case parseURIRelaxed url of
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Just u -> checkPolicy uo u False dlfailed $
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case (urlDownloader uo, parseUrlRequest (show u)) of
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(DownloadWithConduit (DownloadWithCurlRestricted r), Just req) -> catchJust
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(matchStatusCodeException (== found302))
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(downloadConduit meterupdate req file uo >> return True)
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(followredir r)
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`catchNonAsync` (dlfailed . show)
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(DownloadWithConduit (DownloadWithCurlRestricted r), Nothing)
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| isfileurl u -> downloadfile u
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| isftpurl u -> downloadcurlrestricted r u url ftpport
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`catchNonAsync` (dlfailed . show)
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| otherwise -> unsupportedUrlScheme u dlfailed
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(DownloadWithCurl _, _)
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| isfileurl u -> downloadfile u
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| otherwise -> downloadcurl url basecurlparams
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Nothing -> do
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liftIO $ debugM "url" url
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dlfailed "invalid url"
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isfileurl u = uriScheme u == "file:"
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isftpurl u = uriScheme u == "ftp:"
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ftpport = 21
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showhttpexception he = do
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let msg = case he of
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HttpExceptionRequest _ (StatusCodeException r _) ->
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B8.toString $ statusMessage $ responseStatus r
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HttpExceptionRequest _ (InternalException ie) ->
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case fromException ie of
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Nothing -> show ie
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Just (ConnectionRestricted why) -> why
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HttpExceptionRequest _ other -> show other
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_ -> show he
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dlfailed msg
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dlfailed msg
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| noerror = return False
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| otherwise = do
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hPutStrLn stderr $ "download failed: " ++ msg
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hFlush stderr
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return False
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basecurlparams = curlParams uo
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[ if noerror
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then Param "-S"
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else Param "-sS"
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, Param "-f"
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, Param "-L"
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, Param "-C", Param "-"
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]
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downloadcurl rawurl curlparams = do
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-- curl does not create destination file
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-- if the url happens to be empty, so pre-create.
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unlessM (doesFileExist file) $
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writeFile file ""
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boolSystem "curl" (curlparams ++ [Param "-o", File file, File rawurl])
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downloadcurlrestricted r u rawurl defport =
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downloadcurl rawurl =<< curlRestrictedParams r u defport basecurlparams
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downloadfile u = do
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let src = unEscapeString (uriPath u)
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withMeteredFile src meterupdate $
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L.writeFile file
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return True
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-- Conduit does not support ftp, so will throw an exception on a
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-- redirect to a ftp url; fall back to curl.
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followredir r ex@(HttpExceptionRequest _ (StatusCodeException resp _)) =
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case headMaybe $ map decodeBS $ getResponseHeader hLocation resp of
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Just url' -> case parseURIRelaxed url' of
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Just u' | isftpurl u' ->
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checkPolicy uo u' False dlfailed $
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downloadcurlrestricted r u' url' ftpport
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_ -> throwIO ex
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Nothing -> throwIO ex
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followredir _ ex = throwIO ex
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{- Download a perhaps large file using conduit, with auto-resume
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- of incomplete downloads.
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-
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- Does not catch exceptions.
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-}
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downloadConduit :: MeterUpdate -> Request -> FilePath -> UrlOptions -> IO ()
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downloadConduit meterupdate req file uo =
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catchMaybeIO (getFileSize file) >>= \case
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Just sz | sz > 0 -> resumedownload sz
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_ -> runResourceT $ do
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liftIO $ debugM "url" (show req')
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resp <- http req' (httpManager uo)
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if responseStatus resp == ok200
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then store zeroBytesProcessed WriteMode resp
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else respfailure resp
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where
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req' = applyRequest uo $ req
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-- Override http-client's default decompression of gzip
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-- compressed files. We want the unmodified file content.
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{ requestHeaders = (hAcceptEncoding, "identity") :
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filter ((/= hAcceptEncoding) . fst)
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(requestHeaders req)
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, decompress = const False
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}
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-- Resume download from where a previous download was interrupted,
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-- when supported by the http server. The server may also opt to
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-- send the whole file rather than resuming.
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resumedownload sz = catchJust
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(matchStatusCodeHeadersException (alreadydownloaded sz))
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dl
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(const noop)
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where
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dl = runResourceT $ do
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let req'' = req' { requestHeaders = resumeFromHeader sz : requestHeaders req }
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liftIO $ debugM "url" (show req'')
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resp <- http req'' (httpManager uo)
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if responseStatus resp == partialContent206
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then store (BytesProcessed sz) AppendMode resp
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else if responseStatus resp == ok200
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then store zeroBytesProcessed WriteMode resp
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else respfailure resp
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alreadydownloaded sz s h = s == requestedRangeNotSatisfiable416
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&& case lookup hContentRange h of
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-- This could be improved by fixing
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-- https://github.com/aristidb/http-types/issues/87
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Just crh -> crh == B8.fromString ("bytes */" ++ show sz)
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-- Some http servers send no Content-Range header when
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-- the range extends beyond the end of the file.
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-- There is no way to distinguish between the file
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-- being the same size on the http server, vs
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-- it being shorter than the file we already have.
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-- So assume we have the whole content of the file
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-- already, the same as wget and curl do.
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Nothing -> True
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store initialp mode resp =
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sinkResponseFile meterupdate initialp file mode resp
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respfailure = giveup . B8.toString . statusMessage . responseStatus
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{- Sinks a Response's body to a file. The file can either be opened in
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- WriteMode or AppendMode. Updates the meter as data is received.
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-
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- Note that the responseStatus is not checked by this function.
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-}
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sinkResponseFile
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:: MonadResource m
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=> MeterUpdate
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-> BytesProcessed
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-> FilePath
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-> IOMode
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-> Response (ConduitM () B8.ByteString m ())
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-> m ()
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sinkResponseFile meterupdate initialp file mode resp = do
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(fr, fh) <- allocate (openBinaryFile file mode) hClose
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runConduit $ responseBody resp .| go initialp fh
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release fr
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where
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go sofar fh = await >>= \case
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Nothing -> return ()
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Just bs -> do
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let sofar' = addBytesProcessed sofar (B.length bs)
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liftIO $ do
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void $ meterupdate sofar'
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B.hPut fh bs
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go sofar' fh
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{- Downloads at least the specified number of bytes from an url. -}
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downloadPartial :: URLString -> UrlOptions -> Int -> IO (Maybe L.ByteString)
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downloadPartial url uo n = case parseURIRelaxed url of
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Nothing -> return Nothing
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Just u -> go u `catchNonAsync` const (return Nothing)
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where
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go u = case parseUrlRequest (show u) of
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Nothing -> return Nothing
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Just req -> do
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let req' = applyRequest uo req
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liftIO $ debugM "url" (show req')
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withResponse req' (httpManager uo) $ \resp ->
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if responseStatus resp == ok200
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then Just <$> brReadSome (responseBody resp) n
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else return Nothing
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{- Allows for spaces and other stuff in urls, properly escaping them. -}
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parseURIRelaxed :: URLString -> Maybe URI
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parseURIRelaxed s = maybe (parseURIRelaxed' s) Just $
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parseURI $ escapeURIString isAllowedInURI s
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parseUrlRequest :: URLString -> Maybe Request
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parseUrlRequest = parseUrlThrow
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{- Some characters like '[' are allowed in eg, the address of
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- an uri, but cannot appear unescaped further along in the uri.
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- This handles that, expensively, by successively escaping each character
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- from the back of the url until the url parses.
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-}
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parseURIRelaxed' :: URLString -> Maybe URI
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parseURIRelaxed' s = go [] (reverse s)
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where
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go back [] = parseURI back
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go back (c:cs) = case parseURI (escapeURIString isAllowedInURI (reverse (c:cs)) ++ back) of
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Just u -> Just u
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Nothing -> go (escapeURIChar escapemore c ++ back) cs
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escapemore '[' = False
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escapemore ']' = False
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escapemore c = isAllowedInURI c
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hAcceptEncoding :: CI.CI B.ByteString
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hAcceptEncoding = "Accept-Encoding"
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hContentDisposition :: CI.CI B.ByteString
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hContentDisposition = "Content-Disposition"
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hContentRange :: CI.CI B.ByteString
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hContentRange = "Content-Range"
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resumeFromHeader :: FileSize -> Header
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|
resumeFromHeader sz = (hRange, renderByteRanges [ByteRangeFrom sz])
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{- Use with eg:
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|
-
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- > catchJust (matchStatusCodeException (== notFound404))
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|
-}
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matchStatusCodeException :: (Status -> Bool) -> HttpException -> Maybe HttpException
|
|
matchStatusCodeException want = matchStatusCodeHeadersException (\s _h -> want s)
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matchStatusCodeHeadersException :: (Status -> ResponseHeaders -> Bool) -> HttpException -> Maybe HttpException
|
|
matchStatusCodeHeadersException want e@(HttpExceptionRequest _ (StatusCodeException r _))
|
|
| want (responseStatus r) (responseHeaders r) = Just e
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|
| otherwise = Nothing
|
|
matchStatusCodeHeadersException _ _ = Nothing
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|
|
{- Use with eg:
|
|
-
|
|
- > catchJust matchHttpException
|
|
-}
|
|
matchHttpException :: HttpException -> Maybe HttpException
|
|
matchHttpException = Just
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|
|
matchHttpExceptionContent :: (HttpExceptionContent -> Bool) -> HttpException -> Maybe HttpException
|
|
matchHttpExceptionContent want e@(HttpExceptionRequest _ hec)
|
|
| want hec = Just e
|
|
| otherwise = Nothing
|
|
matchHttpExceptionContent _ _ = Nothing
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|
|
{- Constructs parameters that prevent curl from accessing any IP addresses
|
|
- blocked by the Restriction. These are added to the input parameters,
|
|
- which should tell curl what to do.
|
|
-
|
|
- This has to disable redirects because it looks up the IP addresses
|
|
- of the host and after limiting to those allowed by the Restriction,
|
|
- makes curl resolve the host to those IP addresses. It doesn't make sense
|
|
- to use this for http anyway, only for ftp or perhaps other protocols
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|
- supported by curl.
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|
-
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|
- Throws an exception if the Restriction blocks all addresses, or
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|
- if the dns lookup fails. A malformed url will also cause an exception.
|
|
-}
|
|
curlRestrictedParams :: Restriction -> URI -> Int -> [CommandParam] -> IO [CommandParam]
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|
curlRestrictedParams r u defport ps = case uriAuthority u of
|
|
Nothing -> giveup "malformed url"
|
|
Just uath -> case uriPort uath of
|
|
"" -> go (uriRegName uath) defport
|
|
-- strict parser because the port we provide to curl
|
|
-- needs to match the port in the url
|
|
(':':s) -> case readMaybe s :: Maybe Int of
|
|
Just p -> go (uriRegName uath) p
|
|
Nothing -> giveup "malformed url"
|
|
_ -> giveup "malformed url"
|
|
where
|
|
go hostname p = do
|
|
proto <- getProtocolNumber "tcp"
|
|
let serv = show p
|
|
let hints = defaultHints
|
|
{ addrFlags = [AI_ADDRCONFIG]
|
|
, addrProtocol = proto
|
|
, addrSocketType = Stream
|
|
}
|
|
addrs <- getAddrInfo (Just hints) (Just hostname) (Just serv)
|
|
case partitionEithers (map checkrestriction addrs) of
|
|
((e:_es), []) -> throwIO e
|
|
(_, as)
|
|
| null as -> throwIO $
|
|
NC.HostNotResolved hostname
|
|
| otherwise -> return $
|
|
(limitresolve p) as ++ ps
|
|
checkrestriction addr = maybe (Right addr) Left $
|
|
checkAddressRestriction r addr
|
|
limitresolve p addrs =
|
|
[ Param "--resolve"
|
|
, Param $ "*:" ++ show p ++ ":" ++ intercalate ":"
|
|
(mapMaybe (bracketaddr <$$> extractIPAddress . addrAddress) addrs)
|
|
-- Don't let a ftp server provide an IP address.
|
|
, Param "--ftp-skip-pasv-ip"
|
|
-- Prevent all http redirects.
|
|
, Param "--max-redirs", Param "0"
|
|
]
|
|
bracketaddr a = "[" ++ a ++ "]"
|