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1 | {-# LANGUAGE DeriveDataTypeable, ViewPatterns #-} | |
2 | {-# OPTIONS_GHC -O2 -Wall #-} | |
3 | ||
4 | import Control.Applicative | |
5 | import Control.Exception | |
6 | import Control.Monad | |
7 | import qualified Data.ByteString.Lazy as B | |
8 | import Data.Dynamic | |
9 | import qualified Data.Map as M | |
10 | import Data.Time.Clock.POSIX | |
11 | import Data.Time.Format | |
12 | import Network.CGI | |
13 | import Numeric | |
14 | import System.FilePath | |
15 | import System.IO | |
16 | import System.IO.Error | |
17 | import System.Locale | |
18 | import System.Posix | |
19 | import System.Posix.Handle | |
20 | ||
21 | encodings :: M.Map String String | |
22 | encodings = M.fromList [ | |
23 | (".gz", "gzip"), | |
24 | (".bz2", "bzip2") | |
25 | ] | |
26 | ||
27 | types :: M.Map String String | |
28 | types = M.fromList [ | |
29 | (".html", "text/html") | |
30 | ] | |
31 | ||
32 | throwExceptionCGI :: Exception e => e -> CGI a | |
33 | throwExceptionCGI = throwCGI . toException | |
34 | ||
35 | catchExceptionCGI :: Exception e => CGI a -> (e -> CGI a) -> CGI a | |
36 | a `catchExceptionCGI` handler = | |
37 | a `catchCGI` \e -> case fromException e of | |
38 | Nothing -> throwCGI e | |
39 | Just e_ -> handler e_ | |
40 | ||
41 | data MyError = NotModified | Forbidden | NotFound | BadMethod | BadRange | |
42 | deriving (Show, Typeable) | |
43 | ||
44 | instance Exception MyError | |
45 | ||
46 | outputMyError :: MyError -> CGI CGIResult | |
47 | outputMyError NotModified = setStatus 304 "Not Modified" >> outputNothing | |
48 | outputMyError Forbidden = outputError 403 "Forbidden" [] | |
49 | outputMyError NotFound = outputError 404 "Not Found" [] | |
50 | outputMyError BadMethod = outputError 405 "Method Not Allowed" [] | |
51 | outputMyError BadRange = outputError 416 "Requested Range Not Satisfiable" [] | |
52 | ||
53 | checkExtension :: FilePath -> CGI () | |
54 | checkExtension file = do | |
55 | let (base, ext) = splitExtension file | |
56 | ext' <- case M.lookup ext encodings of | |
57 | Nothing -> return ext | |
58 | Just e -> do | |
59 | setHeader "Content-Encoding" e | |
60 | return $ takeExtension base | |
61 | ||
62 | case M.lookup ext' types of | |
63 | Nothing -> throwExceptionCGI Forbidden | |
64 | Just t -> setHeader "Content-Type" t | |
65 | ||
66 | checkMethod :: CGI CGIResult -> CGI CGIResult | |
67 | checkMethod rOutput = do | |
68 | m <- requestMethod | |
69 | case m of | |
70 | "HEAD" -> rOutput >> outputNothing | |
71 | "GET" -> rOutput | |
72 | "POST" -> rOutput | |
73 | _ -> throwExceptionCGI BadMethod | |
74 | ||
75 | httpDate :: String | |
76 | httpDate = "%a, %d %b %Y %H:%M:%S %Z" | |
77 | formatHTTPDate :: EpochTime -> String | |
78 | formatHTTPDate = formatTime defaultTimeLocale httpDate . | |
79 | posixSecondsToUTCTime . realToFrac | |
80 | parseHTTPDate :: String -> Maybe EpochTime | |
81 | parseHTTPDate = (fromInteger . floor . utcTimeToPOSIXSeconds <$>) . | |
82 | parseTime defaultTimeLocale httpDate | |
83 | ||
84 | checkModified :: EpochTime -> CGI () | |
85 | checkModified mTime = do | |
86 | setHeader "Last-Modified" $ formatHTTPDate mTime | |
87 | (requestHeader "If-Modified-Since" >>=) $ maybe (return ()) $ \ims -> | |
88 | when (parseHTTPDate ims >= Just mTime) $ throwExceptionCGI NotModified | |
89 | ||
90 | checkIfRange :: EpochTime -> CGI (Maybe ()) | |
91 | checkIfRange mTime = do | |
92 | (requestHeader "If-Range" >>=) $ maybe (return $ Just ()) $ \ir -> | |
93 | return $ if parseHTTPDate ir == Just mTime then Just () else Nothing | |
94 | ||
95 | parseRange :: String -> FileOffset -> Maybe (FileOffset, FileOffset) | |
96 | parseRange (splitAt 6 -> ("bytes=", readDec -> [(a, "-")])) size = | |
97 | Just (a, size - 1) | |
98 | parseRange (splitAt 6 -> ("bytes=", readDec -> [(a, '-':(readDec -> [(b, "")]))])) _ = | |
99 | Just (a, b) | |
100 | parseRange _ _ = Nothing | |
101 | ||
102 | checkRange :: EpochTime -> FileOffset -> CGI (Maybe (FileOffset, FileOffset)) | |
103 | checkRange mTime size = do | |
104 | setHeader "Accept-Ranges" "bytes" | |
105 | (requestHeader "Range" >>=) $ maybe (return Nothing) $ \range -> do | |
106 | (checkIfRange mTime >>=) $ maybe (return Nothing) $ \() -> do | |
107 | case parseRange range size of | |
108 | Just (a, b) | a <= b -> return $ Just (a, b) | |
109 | _ -> throwExceptionCGI BadRange | |
110 | ||
111 | outputAll :: Handle -> FileOffset -> CGI CGIResult | |
112 | outputAll h size = do | |
113 | setHeader "Content-Length" $ show size | |
114 | outputFPS =<< liftIO (B.hGetContents h) | |
115 | ||
116 | outputRange :: Handle -> FileOffset -> Maybe (FileOffset, FileOffset) -> CGI CGIResult | |
117 | outputRange h size Nothing = outputAll h size | |
118 | outputRange h size (Just (a, b)) = do | |
119 | let len = b - a + 1 | |
120 | ||
121 | setStatus 206 "Partial Content" | |
122 | setHeader "Content-Range" $ | |
123 | "bytes " ++ show a ++ "-" ++ show b ++ "/" ++ show size | |
124 | setHeader "Content-Length" $ show len | |
125 | liftIO $ hSeek h AbsoluteSeek (fromIntegral a) | |
126 | outputFPS =<< liftIO (B.hGet h (fromIntegral len)) | |
127 | ||
128 | serveFile :: FilePath -> CGI CGIResult | |
129 | serveFile file = (`catchExceptionCGI` outputMyError) $ do | |
130 | checkExtension file | |
131 | ||
132 | checkMethod $ do | |
133 | ||
134 | let handleOpenError e = | |
135 | if isDoesNotExistError e then throwExceptionCGI NotFound | |
136 | else if isPermissionError e then throwExceptionCGI Forbidden | |
137 | else throwExceptionCGI e | |
138 | h <- liftIO (openBinaryFile file ReadMode) `catchExceptionCGI` handleOpenError | |
139 | let handlePostOpenError e = do | |
140 | liftIO $ hClose h | |
141 | throwCGI e | |
142 | (`catchCGI` handlePostOpenError) $ do | |
143 | ||
144 | status <- liftIO $ hGetStatus h | |
145 | let mTime = modificationTime status | |
146 | size = fileSize status | |
147 | checkModified mTime | |
148 | ||
149 | range <- checkRange mTime size | |
150 | outputRange h size range | |
151 | ||
152 | main :: IO () | |
153 | main = runCGI $ handleErrors $ serveFile =<< pathTranslated |