diff options
Diffstat (limited to 'Codec')
| -rw-r--r-- | Codec/MIME/Parse.hs | 319 | ||||
| -rw-r--r-- | Codec/MIME/Type.hs | 98 | ||||
| -rw-r--r-- | Codec/MIME/Utils.hs | 3 |
3 files changed, 214 insertions, 206 deletions
diff --git a/Codec/MIME/Parse.hs b/Codec/MIME/Parse.hs index dfe2115..f2d275d 100644 --- a/Codec/MIME/Parse.hs +++ b/Codec/MIME/Parse.hs @@ -1,3 +1,4 @@ +{-# LANGUAGE OverloadedStrings #-} -------------------------------------------------------------------- -- | -- Module : Codec.MIME.Pare @@ -12,14 +13,15 @@ -- -------------------------------------------------------------------- module Codec.MIME.Parse - ( parseMIMEBody -- :: [(String,String)] -> String -> MIMEValue - , parseMIMEType -- :: String -> Maybe Type - , parseMIMEMessage -- :: String -> MIMEValue - - , parseHeaders -- :: String -> ([(String,String)], String) - , parseMultipart -- :: Type -> String -> (MIMEValue, String) - , parseContentType -- :: String -> Maybe Type - , splitMulti -- :: String -> String -> ([MIMEValue], String) + ( parseMIMEBody -- :: [(T.Text,T.Text)] -> T.Text -> MIMEValue + , parseMIMEType -- :: T.Text -> Maybe Type + , parseMIMEMessage -- :: T.Text -> MIMEValue + + , parseHeaders -- :: T.Text -> ([(T.Text,T.Text)], T.Text) + , parseMultipart -- :: Type -> T.Text -> (MIMEValue, T.Text) + , parseContentType -- :: T.Text -> Maybe Type + , splitMulti -- :: T.Text -> T.Text -> ([MIMEValue], T.Text) + , normalizeCRLF ) where import Codec.MIME.Type @@ -27,8 +29,10 @@ import Codec.MIME.Decode import Data.Char import Data.Maybe -import Data.List +import qualified Data.List as L import Debug.Trace ( trace ) +import qualified Data.Text as T +import Data.Monoid(Monoid(..), (<>)) enableTrace :: Bool enableTrace = False @@ -38,7 +42,7 @@ doTrace | enableTrace = trace | otherwise = \_ x -> x -parseMIMEBody :: [(String,String)] -> String -> MIMEValue +parseMIMEBody :: [MIMEParam] -> T.Text -> MIMEValue parseMIMEBody headers_in body = result { mime_val_headers = headers } where result = case mimeType mty of @@ -48,84 +52,89 @@ parseMIMEBody headers_in body = result { mime_val_headers = headers } , mime_val_disp = parseContentDisp headers , mime_val_content = Single (processBody headers body) } - headers = [ (map toLower k,v) | (k,v) <- headers_in ] + headers = [ MIMEParam (T.toLower k) v | (MIMEParam k v) <- headers_in ] mty = fromMaybe defaultType - (parseContentType =<< lookupField "content-type" headers) + (parseContentType =<< lookupField "content-type" (paramPairs headers)) defaultType :: Type defaultType = Type { mimeType = Text "plain" - , mimeParams = [("charset", "us-ascii")] + , mimeParams = [MIMEParam "charset" "us-ascii"] } -parseContentDisp :: [(String,String)] -> Maybe Disposition +parseContentDisp :: [MIMEParam] -> Maybe Disposition parseContentDisp headers = - (processDisp . dropFoldingWSP) =<< lookupField "content-disposition" headers + (processDisp . dropFoldingWSP) =<< lookupField "content-disposition" (paramPairs headers) where - processDisp "" = Nothing - processDisp xs = Just $ - case break (\ch -> isSpace ch || ch == ';') xs of - (as,"") -> Disposition { dispType = toDispType (map toLower as) - , dispParams = [] - } - (as,bs) -> Disposition { dispType = toDispType (map toLower as) - , dispParams = processParams (parseParams bs) - } - - processParams = map procP - where - procP (as,val) - | "name" == asl = Name val - | "filename" == asl = Filename val - | "creation-date" == asl = CreationDate val - | "modification-date" == asl = ModDate val - | "read-date" == asl = ReadDate val - | "size" == asl = Size val - | otherwise = OtherParam (map toLower as) val - where asl = map toLower as - - toDispType t = case t of - "inline" -> DispInline - "attachment" -> DispAttachment - "form-data" -> DispFormData - _ -> DispOther t - -processBody :: [(String,String)] -> String -> String + processDisp t | T.null t = Nothing + | T.null bs = Just $ Disposition { dispType = toDispType (T.toLower as) + , dispParams = [] + } + | otherwise = Just $ Disposition { dispType = toDispType (T.toLower as) + , dispParams = processParams (parseParams bs) + } + where (as,bs) = T.break (\ch -> isSpace ch || ch == ';') t + + processParams = map procP + where + procP (MIMEParam as val) + | "name" == asl = Name val + | "filename" == asl = Filename val + | "creation-date" == asl = CreationDate val + | "modification-date" == asl = ModDate val + | "read-date" == asl = ReadDate val + | "size" == asl = Size val + | otherwise = OtherParam asl val + where asl = T.toLower as + + toDispType t = if t == "inline" then DispInline + else if t == "attachment" then DispAttachment + else if t == "form-data" then DispFormData + else DispOther t + +paramPairs :: [MIMEParam] -> [(T.Text, T.Text)] +paramPairs = map paramPair + where + paramPair (MIMEParam a b) = (a,b) + +processBody :: [MIMEParam] -> T.Text -> T.Text processBody headers body = - case lookupField "content-transfer-encoding" headers of + case lookupField "content-transfer-encoding" $ paramPairs headers of Nothing -> body - Just v -> decodeBody v body - -normalizeCRLF :: String -> String -normalizeCRLF ('\r':'\n':xs) = '\r':'\n':normalizeCRLF xs -normalizeCRLF ('\r':xs) = '\r':'\n':normalizeCRLF xs -normalizeCRLF ('\n':xs) = '\r':'\n':normalizeCRLF xs -normalizeCRLF (x:xs) = x:normalizeCRLF xs -normalizeCRLF [] = [] + Just v -> T.pack $ decodeBody (T.unpack v) $ T.unpack body + +normalizeCRLF :: T.Text -> T.Text +normalizeCRLF t + | T.null t = "" + | "\r\n" `T.isPrefixOf` t = "\r\n" <> normalizeCRLF (T.drop 2 t) + | any (`T.isPrefixOf` t) ["\r", "\n"] = "\r\n" <> normalizeCRLF (T.drop 1 t) + | otherwise = let (a,b) = T.break (`elem` "\r\n") t in a <> normalizeCRLF b -parseMIMEMessage :: String -> MIMEValue +parseMIMEMessage :: T.Text -> MIMEValue parseMIMEMessage entity = case parseHeaders (normalizeCRLF entity) of (as,bs) -> parseMIMEBody as bs -parseHeaders :: String -> ([(String,String)], String) +parseHeaders :: T.Text -> ([MIMEParam], T.Text) parseHeaders str = case findFieldName "" str of Left (nm, rs) -> parseFieldValue nm (dropFoldingWSP rs) Right body -> ([],body) where - findFieldName _acc "" = Right "" - findFieldName _acc ('\r':'\n':xs) = Right xs - findFieldName acc (':':xs) = Left (reverse (dropWhile isHSpace acc), xs) - findFieldName acc (x:xs) = findFieldName (x:acc) xs - - parseFieldValue nm xs = - case takeUntilCRLF xs of - (as,"") -> ([(nm,as)],"") - (as,bs) -> let (zs,ys) = parseHeaders bs in ((nm,as):zs,ys) - -parseMultipart :: Type -> String -> (MIMEValue, String) + findFieldName acc t + | T.null t = Right "" + | "\r\n" `T.isPrefixOf` t = Right $ T.drop 2 t + | ":" `T.isPrefixOf` t = Left (T.reverse $ T.dropWhile isHSpace acc, t) + | otherwise = findFieldName (T.take 1 t <> acc) $ T.drop 1 t + + parseFieldValue nm xs + | T.null bs = ([MIMEParam nm as], "") + | otherwise = let (zs,ys) = parseHeaders bs in (MIMEParam nm as :zs, ys) + where + (as,bs) = takeUntilCRLF xs + +parseMultipart :: Type -> T.Text -> (MIMEValue, T.Text) parseMultipart mty body = - case lookupField "boundary" (mimeParams mty) of - Nothing -> doTrace ("Multipart mime type, " ++ showType mty ++ + case lookupField "boundary" (paramPairs $ mimeParams mty) of + Nothing -> doTrace ("Multipart mime type, " ++ T.unpack (showType mty) ++ ", has no required boundary parameter. Defaulting to text/plain") $ (nullMIMEValue{ mime_val_type = defaultType , mime_val_disp = Nothing @@ -137,71 +146,71 @@ parseMultipart mty body = }, rs) where (vals,rs) = splitMulti bnd body -splitMulti :: String -> String -> ([MIMEValue], String) +splitMulti :: T.Text -> T.Text -> ([MIMEValue], T.Text) splitMulti bnd body_in = -- Note: we insert a CRLF if it looks as if the boundary string starts -- right off the bat. No harm done if this turns out to be incorrect. - let body = case body_in of - '-':'-':_ -> ('\r':'\n':body_in) - _ -> body_in + let body | "--" `T.isPrefixOf` body_in = "\r\n" <> body_in + | otherwise = body_in in case untilMatch dashBoundary body of - Nothing -> ([],"") - Just ('-':'-':xs) -> ([],xs) - Just xs -> splitMulti1 (dropTrailer xs) + Nothing -> mempty + Just xs | "--" `T.isPrefixOf` xs -> ([], T.drop 2 xs) + | otherwise -> splitMulti1 (dropTrailer xs) where - dashBoundary = ("\r\n--" ++ bnd) - - splitMulti1 xs = - case matchUntil dashBoundary xs of - ("","") -> ([],"") - (as,"") -> ([parseMIMEMessage as],"") - (as,'-':'-':bs) -> ([parseMIMEMessage as], dropTrailer bs) - (as,bs) -> let (zs,ys) = splitMulti1 (dropTrailer bs) - in ((parseMIMEMessage as) : zs,ys) - - dropTrailer xs = - case dropWhile isHSpace xs of - '\r':'\n':xs1 -> xs1 - xs1 -> xs1 -- hmm, flag an error? - -parseMIMEType :: String -> Maybe Type + dashBoundary = ("\r\n--" <> bnd) + + splitMulti1 xs + | T.null as && T.null bs = ([], "") + | T.null bs = ([parseMIMEMessage as],"") + | T.isPrefixOf "--" bs = ([parseMIMEMessage as], dropTrailer bs) + | otherwise = let (zs,ys) = splitMulti1 (dropTrailer bs) + in ((parseMIMEMessage as) : zs,ys) + + where + (as,bs) = matchUntil dashBoundary xs + + dropTrailer xs + | "\r\n" `T.isPrefixOf` xs1 = T.drop 2 xs1 + | otherwise = xs1 -- hmm, flag an error? + where + xs1 = T.dropWhile isHSpace xs + +parseMIMEType :: T.Text -> Maybe Type parseMIMEType = parseContentType -parseContentType :: String -> Maybe Type -parseContentType str = - case break (=='/') (dropFoldingWSP str) of - (maj,_:minor) -> - case break (\ ch -> isHSpace ch || isTSpecial ch) minor of - (as,bs) -> - Just Type { mimeType = toType maj as - , mimeParams = parseParams (dropWhile isHSpace bs) - } - _ -> doTrace ("unable to parse content-type: " ++ show str) $ Nothing - where - toType a b = case lookupField (map toLower a) mediaTypes of - Just ctor -> ctor b - _ -> Other a b - -parseParams :: String -> [(String,String)] -parseParams "" = [] -parseParams (';':xs) = - case break (=='=') (dropFoldingWSP xs) of - (_,[]) -> [] - (nm_raw,_:vs) -> - case vs of - '"':vs1 -> - case break (=='"') vs1 of - (val,"") -> [(nm,val)] - (val,_:zs) -> (nm,val):parseParams (dropWhile isHSpace zs) - _ -> case break (\ ch -> isHSpace ch || isTSpecial ch) vs of - (val,zs) -> (nm,val):parseParams (dropWhile isHSpace zs) - where - nm = map toLower nm_raw - -parseParams cs = doTrace ("Codec.MIME.Parse.parseParams: curious param value -- " ++ show cs) [] - -mediaTypes :: [(String, String -> MIMEType)] +parseContentType :: T.Text -> Maybe Type +parseContentType str + | T.null minor0 = doTrace ("unable to parse content-type: " ++ show str) $ Nothing + | otherwise = Just Type { mimeType = toType maj as + , mimeParams = parseParams (T.dropWhile isHSpace bs) + } + where + (maj, minor0) = T.break (=='/') (dropFoldingWSP str) + minor = T.drop 1 minor0 + (as, bs) = T.break (\ ch -> isHSpace ch || isTSpecial ch) minor + toType a b = case lookupField (T.toLower a) mediaTypes of + Just ctor -> ctor b + _ -> Other a b + +parseParams :: T.Text -> [MIMEParam] +parseParams t | T.null t = [] + | ';' == T.head t = let (nm_raw, vs0) = T.break (=='=') (dropFoldingWSP $ T.tail t) + nm = T.toLower nm_raw in + if T.null vs0 + then [] + else let vs = T.tail vs0 in + if not (T.null vs) && T.head vs == '"' + then let vs1 = T.tail vs + (val, zs0) = T.break (=='"') vs1 in + if T.null zs0 + then [MIMEParam nm val] + else MIMEParam nm val : parseParams (T.dropWhile isHSpace $ T.tail zs0) + else let (val, zs) = T.break (\ch -> isHSpace ch || isTSpecial ch) vs in + MIMEParam nm val : parseParams (T.dropWhile isHSpace zs) + | otherwise = doTrace ("Codec.MIME.Parse.parseParams: curious param value -- " ++ show t) [] + +mediaTypes :: [(T.Text, T.Text -> MIMEType)] mediaTypes = [ ("multipart", (Multipart . toMultipart)) , ("application", Application) @@ -212,12 +221,11 @@ mediaTypes = , ("text", Text) , ("video", Video) ] - where toMultipart b = fromMaybe other (lookupField (map toLower b) multipartTypes) - where other = case b of - 'x':'-':_ -> Extension b - _ -> OtherMulti b + where toMultipart b = fromMaybe other (lookupField (T.toLower b) multipartTypes) + where other | T.isPrefixOf "x-" b = Extension b + | otherwise = OtherMulti b -multipartTypes :: [(String, Multipart)] +multipartTypes :: [(T.Text, Multipart)] multipartTypes = [ ("alternative", Alternative) , ("byteranges", Byteranges) @@ -230,18 +238,19 @@ multipartTypes = , ("signed", Signed) ] -untilMatch :: String -> String -> Maybe String -untilMatch "" a = Just a -untilMatch _ "" = Nothing -untilMatch a b | a `isPrefixOf` b = Just $ drop (length a) b -untilMatch a (_:bs) = untilMatch a bs +untilMatch :: T.Text -> T.Text -> Maybe T.Text +untilMatch a b | T.null a = Just b + | T.null b = Nothing + | a `T.isPrefixOf` b = Just $ T.drop (T.length a) b + | otherwise = untilMatch a $ T.tail b -matchUntil :: String -> String -> (String, String) +matchUntil :: T.Text -> T.Text -> (T.Text, T.Text) matchUntil _ "" = ("", "") matchUntil str xs + | T.null xs = mempty -- slow, but it'll do for now. - | str `isPrefixOf` xs = ("", drop (length str) xs) -matchUntil str (x:xs) = let (as,bs) = matchUntil str xs in (x:as,bs) + | str `T.isPrefixOf` xs = ("", T.drop (T.length str) xs) + | otherwise = let (as,bs) = matchUntil str $ T.tail xs in (T.take 1 xs <> as, bs) isHSpace :: Char -> Bool isHSpace c = c == ' ' || c == '\t' @@ -249,25 +258,25 @@ isHSpace c = c == ' ' || c == '\t' isTSpecial :: Char -> Bool isTSpecial x = x `elem` "()<>@,;:\\\"/[]?=" -- " -dropFoldingWSP :: String -> String -dropFoldingWSP "" = "" -dropFoldingWSP (x:xs) - | isHSpace x = dropFoldingWSP xs -dropFoldingWSP ('\r':'\n':x:xs) - | isHSpace x = dropFoldingWSP xs -dropFoldingWSP (x:xs) = x:xs +dropFoldingWSP :: T.Text -> T.Text +dropFoldingWSP t | T.null t = "" + | isHSpace (T.head t) = dropFoldingWSP $ T.tail t + | "\r\n" `T.isPrefixOf` t && not (T.null $ T.drop 2 t) && isHSpace (T.head $ T.drop 2 t) + = dropFoldingWSP $ T.drop 3 t + | otherwise = t -takeUntilCRLF :: String -> (String, String) +takeUntilCRLF :: T.Text -> (T.Text, T.Text) takeUntilCRLF str = go "" str where - go acc "" = (reverse (dropWhile isHSpace acc), "") - go acc ('\r':'\n':x:xs) - | isHSpace x = go (' ':acc) xs - | otherwise = (reverse (dropWhile isHSpace acc), x:xs) - go acc (x:xs) = go (x:acc) xs + go acc t | T.null t = (T.reverse (T.dropWhile isHSpace acc), "") + | "\r\n" `T.isPrefixOf` t && not (T.null $ T.drop 2 t) && isHSpace (T.head $ T.drop 2 t) + = go (" " <> acc) (T.drop 3 t) + | "\r\n" `T.isPrefixOf` t && not (T.null $ T.drop 2 t) + = (T.reverse (T.dropWhile isHSpace acc), T.drop 2 t) + | otherwise = go (T.take 1 t <> acc) $ T.tail t -- case in-sensitive lookup of field names or attributes\/parameters. -lookupField :: String -> [(String,a)] -> Maybe a +lookupField :: T.Text -> [(T.Text,a)] -> Maybe a lookupField n ns = -- assume that inputs have been mostly normalized already -- (i.e., lower-cased), but should the lookup fail fall back @@ -275,8 +284,6 @@ lookupField n ns = case lookup n ns of x@Just{} -> x Nothing -> - let nl = map toLower n in - case find (\ (y,_) -> nl == map toLower y) ns of - Nothing -> Nothing - Just (_,x) -> Just x + let nl = T.toLower n in + fmap snd $ L.find ((nl==) . T.toLower . fst) ns diff --git a/Codec/MIME/Type.hs b/Codec/MIME/Type.hs index 675d29e..68a1b65 100644 --- a/Codec/MIME/Type.hs +++ b/Codec/MIME/Type.hs @@ -1,3 +1,4 @@ +{-# LANGUAGE OverloadedStrings #-} -------------------------------------------------------------------- -- | -- Module : Codec.MIME.Type @@ -14,12 +15,16 @@ -------------------------------------------------------------------- module Codec.MIME.Type where -import Data.List ( isSuffixOf ) +import qualified Data.Text as T +import Data.Monoid ((<>)) -data Type - = Type +data MIMEParam = MIMEParam { paramName :: T.Text + , paramValue :: T.Text } + deriving (Show, Ord, Eq) + +data Type = Type { mimeType :: MIMEType - , mimeParams :: [(String,String)] + , mimeParams :: [MIMEParam] } deriving ( Show, Ord, Eq ) -- | The @null@ MIME record type value; currently a @text/plain@. @@ -29,13 +34,13 @@ nullType = Type , mimeParams = [] } -showType :: Type -> String -showType t = showMIMEType (mimeType t) ++ showMIMEParams (mimeParams t) +showType :: Type -> T.Text +showType t = showMIMEType (mimeType t) <> showMIMEParams (mimeParams t) -showMIMEParams :: [(String,String)] -> String -showMIMEParams ps = concatMap showP ps - where - showP (a,b) = ';':' ':a ++ '=':'"':b ++ "\"" +showMIMEParams :: [MIMEParam] -> T.Text +showMIMEParams ps = T.concat $ map showP ps + where + showP (MIMEParam a b) = "; " <> a <> "=\"" <> b <> "\"" data MIMEType @@ -47,46 +52,41 @@ data MIMEType | Multipart Multipart | Text TextType | Video SubType - | Other String SubType + | Other T.Text SubType deriving ( Show, Ord, Eq ) -showMIMEType :: MIMEType -> String +showMIMEType :: MIMEType -> T.Text showMIMEType t = case t of - Application s -> "application/"++s - Audio s -> "audio/"++s - Image s -> "image/"++s - Message s -> "message/"++s - Model s -> "model/"++s - Multipart s -> "multipart/"++showMultipart s - Text s -> "text/"++s - Video s -> "video/"++s - Other a b -> a ++ '/':b + Application s -> "application/"<>s + Audio s -> "audio/"<>s + Image s -> "image/"<>s + Message s -> "message/"<>s + Model s -> "model/"<>s + Multipart s -> "multipart/"<>showMultipart s + Text s -> "text/"<>s + Video s -> "video/"<>s + Other a b -> a <> "/" <> b -- | a (type, subtype) MIME pair. data MIMEPair - = MIMEPair String SubType + = MIMEPair T.Text SubType deriving ( Eq ) -showMIMEPair :: MIMEPair -> String -showMIMEPair (MIMEPair a b) = a ++ '/':b +showMIMEPair :: MIMEPair -> T.Text +showMIMEPair (MIMEPair a b) = a <> "/" <> b -- | default subtype representation. -type SubType = String +type SubType = T.Text -- | subtype for text content; currently just a string. type TextType = SubType -subTypeString :: Type -> String -subTypeString t = - case break (=='/') (showMIMEType (mimeType t)) of - (_,"") -> "" - (_,_:bs) -> bs +subTypeString :: Type -> T.Text +subTypeString t = T.drop 1 $ snd $ T.break (=='/') (showMIMEType (mimeType t)) -majTypeString :: Type -> String -majTypeString t = - case break (=='/') (showMIMEType (mimeType t)) of - (as,_) -> as +majTypeString :: Type -> T.Text +majTypeString t = fst $ T.break (=='/') (showMIMEType (mimeType t)) data Multipart = Alternative @@ -98,8 +98,8 @@ data Multipart | Parallel | Related | Signed - | Extension String -- ^ e.g., 'x-foo' (i.e., includes the 'x-' bit) - | OtherMulti String -- unrecognized\/uninterpreted. + | Extension T.Text -- ^ e.g., 'x-foo' (i.e., includes the 'x-' bit) + | OtherMulti T.Text -- unrecognized\/uninterpreted. -- (e.g., appledouble, voice-message, etc.) deriving ( Show, Ord, Eq ) @@ -107,7 +107,7 @@ isXmlBased :: Type -> Bool isXmlBased t = case mimeType t of Multipart{} -> False - _ -> "+xml" `isSuffixOf` subTypeString t + _ -> "+xml" `T.isSuffixOf` subTypeString t isXmlType :: Type -> Bool isXmlType t = isXmlBased t || @@ -117,14 +117,14 @@ isXmlType t = isXmlBased t || _ -> False where -- Note: xml-dtd isn't considered an XML type here. - xml_media_types :: [String] + xml_media_types :: [T.Text] xml_media_types = [ "xml" , "xml-external-parsed-entity" ] -showMultipart :: Multipart -> String +showMultipart :: Multipart -> T.Text showMultipart m = case m of Alternative -> "alternative" @@ -139,13 +139,13 @@ showMultipart m = Extension e -> e OtherMulti e -> e -type Content = String +type Content = T.Text data MIMEValue = MIMEValue { mime_val_type :: Type , mime_val_disp :: Maybe Disposition , mime_val_content :: MIMEContent - , mime_val_headers :: [(String,String)] + , mime_val_headers :: [MIMEParam] , mime_val_inc_type :: Bool } deriving ( Show, Eq ) @@ -173,15 +173,15 @@ data DispType = DispInline | DispAttachment | DispFormData - | DispOther String + | DispOther T.Text deriving ( Show, Eq) data DispParam - = Name String - | Filename String - | CreationDate String - | ModDate String - | ReadDate String - | Size String - | OtherParam String String + = Name T.Text + | Filename T.Text + | CreationDate T.Text + | ModDate T.Text + | ReadDate T.Text + | Size T.Text + | OtherParam T.Text T.Text deriving ( Show, Eq) diff --git a/Codec/MIME/Utils.hs b/Codec/MIME/Utils.hs index 8606342..dd54860 100644 --- a/Codec/MIME/Utils.hs +++ b/Codec/MIME/Utils.hs @@ -18,10 +18,11 @@ module Codec.MIME.Utils import Codec.MIME.Type import Data.List ( find ) import Control.Monad ( msum ) +import Data.Text(Text) -- | Given a parameter name, locate it within a MIME value, -- returning the corresponding (sub) MIME value. -findMultipartNamed :: String -> MIMEValue -> Maybe MIMEValue +findMultipartNamed :: Text -> MIMEValue -> Maybe MIMEValue findMultipartNamed nm mv = case mime_val_content mv of Multi ms -> msum (map (findMultipartNamed nm) ms) |