dns-4.0.0: Network/DNS/StateBinary.hs
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE CPP #-}
module Network.DNS.StateBinary (
PState(..)
, initialState
, SPut
, runSPut
, put8
, put16
, put32
, putInt8
, putInt16
, putInt32
, putByteString
, putReplicate
, SGet
, failSGet
, fitSGet
, runSGet
, runSGetAt
, runSGetWithLeftovers
, runSGetWithLeftoversAt
, get8
, get16
, get32
, getInt8
, getInt16
, getInt32
, getNByteString
, sGetMany
, getPosition
, getInput
, getAtTime
, wsPop
, wsPush
, wsPosition
, addPositionW
, push
, pop
, getNBytes
, getNoctets
, skipNBytes
, parseLabel
, unparseLabel
) where
import qualified Control.Exception as E
import Control.Monad.State.Strict (State, StateT)
import qualified Control.Monad.State.Strict as ST
import qualified Data.Attoparsec.ByteString as A
import qualified Data.Attoparsec.Types as T
import qualified Data.ByteString as BS
import qualified Data.ByteString.Char8 as S8
import Data.ByteString.Builder (Builder)
import qualified Data.ByteString.Builder as BB
import qualified Data.ByteString.Lazy as LB
import qualified Data.ByteString.Lazy.Char8 as LBS
import Data.IntMap (IntMap)
import qualified Data.IntMap as IM
import Data.Map (Map)
import qualified Data.Map as M
import Data.Semigroup as Sem
import Network.DNS.Imports
import Network.DNS.Types
----------------------------------------------------------------
type SPut = State WState Builder
data WState = WState {
wsDomain :: Map Domain Int
, wsPosition :: Int
}
initialWState :: WState
initialWState = WState M.empty 0
instance Sem.Semigroup SPut where
p1 <> p2 = (Sem.<>) <$> p1 <*> p2
instance Monoid SPut where
mempty = return mempty
#if !(MIN_VERSION_base(4,11,0))
mappend = (Sem.<>)
#endif
put8 :: Word8 -> SPut
put8 = fixedSized 1 BB.word8
put16 :: Word16 -> SPut
put16 = fixedSized 2 BB.word16BE
put32 :: Word32 -> SPut
put32 = fixedSized 4 BB.word32BE
putInt8 :: Int -> SPut
putInt8 = fixedSized 1 (BB.int8 . fromIntegral)
putInt16 :: Int -> SPut
putInt16 = fixedSized 2 (BB.int16BE . fromIntegral)
putInt32 :: Int -> SPut
putInt32 = fixedSized 4 (BB.int32BE . fromIntegral)
putByteString :: ByteString -> SPut
putByteString = writeSized BS.length BB.byteString
putReplicate :: Int -> Word8 -> SPut
putReplicate n w =
fixedSized n BB.lazyByteString $ LB.replicate (fromIntegral n) w
addPositionW :: Int -> State WState ()
addPositionW n = do
(WState m cur) <- ST.get
ST.put $ WState m (cur+n)
fixedSized :: Int -> (a -> Builder) -> a -> SPut
fixedSized n f a = do addPositionW n
return (f a)
writeSized :: (a -> Int) -> (a -> Builder) -> a -> SPut
writeSized n f a = do addPositionW (n a)
return (f a)
wsPop :: Domain -> State WState (Maybe Int)
wsPop dom = do
doms <- ST.gets wsDomain
return $ M.lookup dom doms
wsPush :: Domain -> Int -> State WState ()
wsPush dom pos = do
(WState m cur) <- ST.get
ST.put $ WState (M.insert dom pos m) cur
----------------------------------------------------------------
type SGet = StateT PState (T.Parser ByteString)
data PState = PState {
psDomain :: IntMap Domain
, psPosition :: Int
, psInput :: ByteString
, psAtTime :: Int64
}
----------------------------------------------------------------
getPosition :: SGet Int
getPosition = ST.gets psPosition
getInput :: SGet ByteString
getInput = ST.gets psInput
getAtTime :: SGet Int64
getAtTime = ST.gets psAtTime
addPosition :: Int -> SGet ()
addPosition n | n < 0 = failSGet "internal error: negative position increment"
| otherwise = do
PState dom pos inp t <- ST.get
let !pos' = pos + n
when (pos' > BS.length inp) $
failSGet "malformed or truncated input"
ST.put $ PState dom pos' inp t
push :: Int -> Domain -> SGet ()
push n d = do
PState dom pos inp t <- ST.get
ST.put $ PState (IM.insert n d dom) pos inp t
pop :: Int -> SGet (Maybe Domain)
pop n = ST.gets (IM.lookup n . psDomain)
----------------------------------------------------------------
get8 :: SGet Word8
get8 = ST.lift A.anyWord8 <* addPosition 1
get16 :: SGet Word16
get16 = ST.lift getWord16be <* addPosition 2
where
word8' = fromIntegral <$> A.anyWord8
getWord16be = do
a <- word8'
b <- word8'
return $ a * 0x100 + b
get32 :: SGet Word32
get32 = ST.lift getWord32be <* addPosition 4
where
word8' = fromIntegral <$> A.anyWord8
getWord32be = do
a <- word8'
b <- word8'
c <- word8'
d <- word8'
return $ a * 0x1000000 + b * 0x10000 + c * 0x100 + d
getInt8 :: SGet Int
getInt8 = fromIntegral <$> get8
getInt16 :: SGet Int
getInt16 = fromIntegral <$> get16
getInt32 :: SGet Int
getInt32 = fromIntegral <$> get32
----------------------------------------------------------------
overrun :: SGet a
overrun = failSGet "malformed or truncated input"
getNBytes :: Int -> SGet [Int]
getNBytes n | n < 0 = overrun
| otherwise = toInts <$> getNByteString n
where
toInts = map fromIntegral . BS.unpack
getNoctets :: Int -> SGet [Word8]
getNoctets n | n < 0 = overrun
| otherwise = BS.unpack <$> getNByteString n
skipNBytes :: Int -> SGet ()
skipNBytes n | n < 0 = overrun
| otherwise = ST.lift (A.take n) >> addPosition n
getNByteString :: Int -> SGet ByteString
getNByteString n | n < 0 = overrun
| otherwise = ST.lift (A.take n) <* addPosition n
fitSGet :: Int -> SGet a -> SGet a
fitSGet len parser | len < 0 = overrun
| otherwise = do
pos0 <- getPosition
ret <- parser
pos' <- getPosition
if pos' == pos0 + len
then return $! ret
else if pos' > pos0 + len
then failSGet "element size exceeds declared size"
else failSGet "element shorter than declared size"
-- | Parse a list of elements that takes up exactly a given number of bytes.
-- In order to avoid infinite loops, if an element parser succeeds without
-- moving the buffer offset forward, an error will be returned.
--
sGetMany :: String -- ^ element type for error messages
-> Int -- ^ input buffer length
-> SGet a -- ^ element parser
-> SGet [a]
sGetMany elemname len parser | len < 0 = overrun
| otherwise = go len []
where
go n xs
| n < 0 = failSGet $ elemname ++ " longer than declared size"
| n == 0 = pure $ reverse xs
| otherwise = do
pos0 <- getPosition
x <- parser
pos1 <- getPosition
if pos1 <= pos0
then failSGet $ "internal error: in-place success for " ++ elemname
else go (n + pos0 - pos1) (x : xs)
----------------------------------------------------------------
-- | To get a broad range of correct RRSIG inception and expiration times
-- without over or underflow, we choose a time half way between midnight PDT
-- 2010-07-15 (the day the root zone was signed) and 2^32 seconds later on
-- 2146-08-21. Since 'decode' and 'runSGet' are pure, we can't peek at the
-- current time while parsing. Outside this date range the output is off by
-- some non-zero multiple 2\^32 seconds.
--
dnsTimeMid :: Int64
dnsTimeMid = 3426660848
initialState :: Int64 -> ByteString -> PState
initialState t inp = PState IM.empty 0 inp t
-- Construct our own error message, without the unhelpful AttoParsec
-- \"Failed reading: \" prefix.
--
failSGet :: String -> SGet a
failSGet msg = ST.lift (fail "" A.<?> msg)
runSGetAt :: Int64 -> SGet a -> ByteString -> Either DNSError (a, PState)
runSGetAt t parser inp =
toResult $ A.parse (ST.runStateT parser $ initialState t inp) inp
where
toResult :: A.Result r -> Either DNSError r
toResult (A.Done _ r) = Right r
toResult (A.Fail _ ctx msg) = Left $ DecodeError $ head $ ctx ++ [msg]
toResult (A.Partial _) = Left $ DecodeError "incomplete input"
runSGet :: SGet a -> ByteString -> Either DNSError (a, PState)
runSGet = runSGetAt dnsTimeMid
runSGetWithLeftoversAt :: Int64 -- ^ Reference time for DNS clock arithmetic
-> SGet a -- ^ Parser
-> ByteString -- ^ Encoded message
-> Either DNSError ((a, PState), ByteString)
runSGetWithLeftoversAt t parser inp =
toResult $ A.parse (ST.runStateT parser $ initialState t inp) inp
where
toResult :: A.Result r -> Either DNSError (r, ByteString)
toResult (A.Done i r) = Right (r, i)
toResult (A.Partial f) = toResult $ f BS.empty
toResult (A.Fail _ ctx e) = Left $ DecodeError $ head $ ctx ++ [e]
runSGetWithLeftovers :: SGet a -> ByteString -> Either DNSError ((a, PState), ByteString)
runSGetWithLeftovers = runSGetWithLeftoversAt dnsTimeMid
runSPut :: SPut -> ByteString
runSPut = LBS.toStrict . BB.toLazyByteString . flip ST.evalState initialWState
----------------------------------------------------------------
-- | Decode a domain name in A-label form to a leading label and a tail with
-- the remaining labels, unescaping backlashed chars and decimal triples along
-- the way. Any U-label conversion belongs at the layer above this code.
--
-- This function is pure, but is not total, it throws an error when presented
-- with malformed input
--
parseLabel :: Word8 -> ByteString -> (ByteString, ByteString)
parseLabel sep dom =
if BS.any (== bslash) dom
then toResult $ A.parse (labelParser sep mempty) dom
else check $ safeTail <$> BS.break (== sep) dom
where
toResult (A.Partial c) = toResult (c mempty)
toResult (A.Done tl hd) = check (hd, tl)
toResult _ = bottom
safeTail bs | BS.null bs = mempty
| otherwise = BS.tail bs
check r@(hd, tl) | not (BS.null hd) || BS.null tl = r
| otherwise = bottom
bottom = E.throw $ DecodeError $ "invalid domain: " ++ S8.unpack dom
labelParser :: Word8 -> ByteString -> A.Parser ByteString
labelParser sep acc = do
acc' <- mappend acc <$> A.option mempty simple
labelEnd sep acc' <|> (escaped >>= labelParser sep . BS.snoc acc')
where
simple = fst <$> A.match skipUnescaped
where
skipUnescaped = A.skipMany1 $ A.satisfy notSepOrBslash
notSepOrBslash w = w /= sep && w /= bslash
escaped = do
A.skip (== bslash)
either decodeDec pure =<< A.eitherP digit A.anyWord8
where
digit = fromIntegral <$> A.satisfyWith (\n -> n - zero) (<=9)
decodeDec d =
safeWord8 =<< trigraph d <$> digit <*> digit
where
trigraph :: Word -> Word -> Word -> Word
trigraph x y z = 100 * x + 10 * y + z
safeWord8 :: Word -> A.Parser Word8
safeWord8 n | n > 255 = mzero
| otherwise = pure $ fromIntegral n
labelEnd :: Word8 -> ByteString -> A.Parser ByteString
labelEnd sep acc =
A.satisfy (== sep) *> pure acc <|>
A.endOfInput *> pure acc
----------------------------------------------------------------
-- | Convert a wire-form label to presentation-form by escaping
-- the separator, special and non-printing characters. For simple
-- labels with no bytes that require escaping we get back the input
-- bytestring asis with no copying or re-construction.
--
-- Note: the separator is required to be either \'.\' or \'\@\', but this
-- constraint is the caller's responsibility and is not checked here.
--
unparseLabel :: Word8 -> ByteString -> ByteString
unparseLabel sep label =
if BS.all (isPlain sep) label
then label
else toResult $ A.parse (labelUnparser sep mempty) label
where
toResult (A.Partial c) = toResult (c mempty)
toResult (A.Done _ r) = r
toResult _ = E.throw UnknownDNSError -- can't happen
labelUnparser :: Word8 -> ByteString -> A.Parser ByteString
labelUnparser sep acc = do
acc' <- mappend acc <$> A.option mempty asis
A.endOfInput *> pure acc' <|> (esc >>= labelUnparser sep . mappend acc')
where
-- Non-printables are escaped as decimal trigraphs, while printable
-- specials just get a backslash prefix.
esc = do
w <- A.anyWord8
if w <= 32 || w >= 127
then let (q100, r100) = w `divMod` 100
(q10, r10) = r100 `divMod` 10
in pure $ BS.pack [ bslash, zero + q100, zero + q10, zero + r10 ]
else pure $ BS.pack [ bslash, w ]
-- Runs of plain bytes are recognized as a single chunk, which is then
-- returned as-is.
asis = fmap fst $ A.match $ A.skipMany1 $ A.satisfy $ isPlain sep
-- | In the presentation form of DNS labels, these characters are escaped by
-- prepending a backlash. (They have special meaning in zone files). Whitespace
-- and other non-printable or non-ascii characters are encoded via "\DDD"
-- decimal escapes. The separator character is also quoted in each label. Note
-- that '@' is quoted even when not the separator.
escSpecials :: ByteString
escSpecials = "\"$();@\\"
-- | Is the given byte the separator or one of the specials?
isSpecial :: Word8 -> Word8 -> Bool
isSpecial sep w = w == sep || BS.elemIndex w escSpecials /= Nothing
-- | Is the given byte a plain byte that reqires no escaping. The tests are
-- ordered to succeed or fail quickly in the most common cases. The test
-- ranges assume the expected numeric values of the named special characters.
-- Note: the separator is assumed to be either '.' or '@' and so not matched by
-- any of the first three fast-path 'True' cases.
isPlain :: Word8 -> Word8 -> Bool
isPlain sep w | w >= 127 = False -- <DEL> + non-ASCII
| w > bslash = True -- ']'..'_'..'a'..'z'..'~'
| w >= zero && w < semi = True -- '0'..'9'..':'
| w > atsign && w < bslash = True -- 'A'..'Z'..'['
| w <= 32 = False -- non-printables
| isSpecial sep w = False -- one of the specials
| otherwise = True -- plain punctuation
-- | Some numeric byte constants.
zero, semi, atsign, bslash :: Word8
zero = fromIntegral $ fromEnum '0' -- 48
semi = fromIntegral $ fromEnum ';' -- 59
atsign = fromIntegral $ fromEnum '@' -- 64
bslash = fromIntegral $ fromEnum '\\' -- 92