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|
{- Url downloading.
-
- Copyright 2011,2013 Joey Hess <joey@kitenet.net>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
module Utility.Url (
URLString,
UserAgent,
UrlOptions(..),
check,
checkBoth,
exists,
download,
downloadQuiet,
parseURIRelaxed
) where
import Common
import Network.URI
import qualified Network.Browser as Browser
import Network.HTTP
import Data.Either
import Data.Default
import qualified Build.SysConfig
type URLString = String
type Headers = [String]
type UserAgent = String
data UrlOptions = UrlOptions
{ userAgent :: Maybe UserAgent
, reqHeaders :: Headers
, reqParams :: [CommandParam]
}
instance Default UrlOptions
where
def = UrlOptions Nothing [] []
{- Checks that an url exists and could be successfully downloaded,
- also checking that its size, if available, matches a specified size. -}
checkBoth :: URLString -> Maybe Integer -> UrlOptions -> IO Bool
checkBoth url expected_size uo = do
v <- check url expected_size uo
return (fst v && snd v)
check :: URLString -> Maybe Integer -> UrlOptions -> IO (Bool, Bool)
check url expected_size = go <$$> exists url
where
go (False, _) = (False, False)
go (True, Nothing) = (True, True)
go (True, s) = case expected_size of
Just _ -> (True, expected_size == s)
Nothing -> (True, True)
{- Checks that an url exists and could be successfully downloaded,
- also returning its size if available.
-
- For a file: url, check it directly.
-
- Uses curl otherwise, when available, since curl handles https better
- than does Haskell's Network.Browser.
-}
exists :: URLString -> UrlOptions -> IO (Bool, Maybe Integer)
exists url uo = case parseURIRelaxed url of
Just u
| uriScheme u == "file:" -> do
s <- catchMaybeIO $ getFileStatus (unEscapeString $ uriPath u)
case s of
Just stat -> return (True, Just $ fromIntegral $ fileSize stat)
Nothing -> dne
| otherwise -> if Build.SysConfig.curl
then do
output <- catchDefaultIO "" $
readProcess "curl" $ toCommand curlparams
case lastMaybe (lines output) of
Just ('2':_:_) -> return (True, extractsize output)
_ -> dne
else do
r <- request u HEAD uo
case rspCode r of
(2,_,_) -> return (True, size r)
_ -> return (False, Nothing)
Nothing -> dne
where
dne = return (False, Nothing)
curlparams = addUserAgent uo $
[ Param "-s"
, Param "--head"
, Param "-L", Param url
, Param "-w", Param "%{http_code}"
] ++ concatMap (\h -> [Param "-H", Param h]) (reqHeaders uo) ++ (reqParams uo)
extractsize s = case lastMaybe $ filter ("Content-Length:" `isPrefixOf`) (lines s) of
Just l -> case lastMaybe $ words l of
Just sz -> readish sz
_ -> Nothing
_ -> Nothing
size = liftM Prelude.read . lookupHeader HdrContentLength . rspHeaders
-- works for both wget and curl commands
addUserAgent :: UrlOptions -> [CommandParam] -> [CommandParam]
addUserAgent uo ps = case userAgent uo of
Nothing -> ps
Just ua -> ps ++ [Param "--user-agent", Param ua]
{- Used to download large files, such as the contents of keys.
-
- Uses wget or curl program for its progress bar. (Wget has a better one,
- so is preferred.) Which program to use is determined at run time; it
- would not be appropriate to test at configure time and build support
- for only one in.
-}
download :: URLString -> FilePath -> UrlOptions -> IO Bool
download = download' False
{- No output, even on error. -}
downloadQuiet :: URLString -> FilePath -> UrlOptions -> IO Bool
downloadQuiet = download' True
download' :: Bool -> URLString -> FilePath -> UrlOptions -> IO Bool
download' quiet url file uo =
case parseURIRelaxed url of
Just u
| uriScheme u == "file:" -> do
-- curl does not create destination file
-- for an empty file:// url, so pre-create
writeFile file ""
curl
| otherwise -> ifM (inPath "wget") (wget , curl)
_ -> return False
where
headerparams = map (\h -> Param $ "--header=" ++ h) (reqHeaders uo)
wget = go "wget" $ headerparams ++ quietopt "-q" ++ wgetparams
{- Regular wget needs --clobber to continue downloading an existing
- file. On Android, busybox wget is used, which does not
- support, or need that option. -}
#ifndef __ANDROID__
wgetparams = [Params "--clobber -c -O"]
#else
wgetparams = [Params "-c -O"]
#endif
{- Uses the -# progress display, because the normal
- one is very confusing when resuming, showing
- the remainder to download as the whole file,
- and not indicating how much percent was
- downloaded before the resume. -}
curl = go "curl" $ headerparams ++ quietopt "-s" ++
[Params "-f -L -C - -# -o"]
go cmd opts = boolSystem cmd $
addUserAgent uo $ reqParams uo++opts++[File file, File url]
quietopt s
| quiet = [Param s]
| otherwise = []
{- Uses Network.Browser to make a http request of an url.
- For example, HEAD can be used to check if the url exists,
- or GET used to get the url content (best for small urls).
-
- This does its own redirect following because Browser's is buggy for HEAD
- requests.
-
- Unfortunately, does not handle https, so should only be used
- when curl is not available.
-}
request :: URI -> RequestMethod -> UrlOptions -> IO (Response String)
request url requesttype uo = go 5 url
where
go :: Int -> URI -> IO (Response String)
go 0 _ = error "Too many redirects "
go n u = do
rsp <- Browser.browse $ do
maybe noop Browser.setUserAgent (userAgent uo)
Browser.setErrHandler ignore
Browser.setOutHandler ignore
Browser.setAllowRedirects False
let req = mkRequest requesttype u :: Request_String
snd <$> Browser.request (addheaders req)
case rspCode rsp of
(3,0,x) | x /= 5 -> redir (n - 1) u rsp
_ -> return rsp
addheaders req = setHeaders req (rqHeaders req ++ userheaders)
userheaders = rights $ map parseHeader (reqHeaders uo)
ignore = const noop
redir n u rsp = case retrieveHeaders HdrLocation rsp of
[] -> return rsp
(Header _ newu:_) ->
case parseURIReference newu of
Nothing -> return rsp
Just newURI -> go n $
#if defined VERSION_network
#if ! MIN_VERSION_network(2,4,0)
#define WITH_OLD_URI
#endif
#endif
#ifdef WITH_OLD_URI
fromMaybe newURI (newURI `relativeTo` u)
#else
newURI `relativeTo` u
#endif
{- Allows for spaces and other stuff in urls, properly escaping them. -}
parseURIRelaxed :: URLString -> Maybe URI
parseURIRelaxed = parseURI . escapeURIString isAllowedInURI
|
