{-# LANGUAGE Rank2Types #-}
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE OverloadedStrings #-}
-- |
-- Module : Network.Socks5.Parse
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : portable
--
-- A very simple bytestring parser related to Parsec and Attoparsec
--
-- Simple example:
--
-- > > parse ((,) <$> take 2 <*> byte 0x20 <*> (bytes "abc" *> anyByte)) "xx abctest"
-- > ParseOK "est" ("xx", 116)
--
module Network.Socks5.Parse
( Parser
, Result(..)
-- * run the Parser
, parse
, parseFeed
-- * Parser methods
, byte
, anyByte
, bytes
, take
, takeWhile
, takeAll
, skip
, skipWhile
, skipAll
, takeStorable
) where
import Control.Applicative
import Control.Monad
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import qualified Data.ByteString.Internal as B (toForeignPtr)
import Data.Word
import Foreign.Storable (Storable, peekByteOff, sizeOf)
import Foreign.ForeignPtr (withForeignPtr)
import Prelude hiding (take, takeWhile)
import System.IO.Unsafe (unsafePerformIO)
-- | Simple parsing result, that represent respectively:
--
-- * failure: with the error message
--
-- * continuation: that need for more input data
--
-- * success: the remaining unparsed data and the parser value
data Result a =
ParseFail String
| ParseMore (ByteString -> Result a)
| ParseOK ByteString a
instance Show a => Show (Result a) where
show (ParseFail err) = "ParseFailure: " ++ err
show (ParseMore _) = "ParseMore _"
show (ParseOK b a) = "ParseOK " ++ show a ++ " " ++ show b
type Failure r = ByteString -> String -> Result r
type Success a r = ByteString -> a -> Result r
-- | Simple ByteString parser structure
newtype Parser a = Parser
{ runParser :: forall r . ByteString -> Failure r -> Success a r -> Result r }
instance Monad Parser where
fail errorMsg = Parser $ \buf err _ -> err buf ("failed: " ++ errorMsg)
return v = Parser $ \buf _ ok -> ok buf v
m >>= k = Parser $ \buf err ok ->
runParser m buf err (\buf' a -> runParser (k a) buf' err ok)
instance MonadPlus Parser where
mzero = fail "Parser.MonadPlus.mzero"
mplus f g = Parser $ \buf err ok ->
-- rewrite the err callback of @f to call @g
runParser f buf (\_ _ -> runParser g buf err ok) ok
instance Functor Parser where
fmap f p = Parser $ \buf err ok ->
runParser p buf err (\b a -> ok b (f a))
instance Applicative Parser where
pure = return
(<*>) d e = d >>= \b -> e >>= \a -> return (b a)
instance Alternative Parser where
empty = fail "Parser.Alternative.empty"
(<|>) = mplus
-- | Run a parser on an @initial ByteString.
--
-- If the Parser need more data than available, the @feeder function
-- is automatically called and fed to the More continuation.
parseFeed :: Monad m => m B.ByteString -> Parser a -> B.ByteString -> m (Result a)
parseFeed feeder p initial = loop $ parse p initial
where loop (ParseMore k) = feeder >>= (loop . k)
loop r = return r
-- | Run a Parser on a ByteString and return a 'Result'
parse :: Parser a -> ByteString -> Result a
parse p s = runParser p s (\_ msg -> ParseFail msg) (\b a -> ParseOK b a)
------------------------------------------------------------
getMore :: Parser ()
getMore = Parser $ \buf err ok -> ParseMore $ \nextChunk ->
if B.null nextChunk
then err buf "EOL: need more data"
else ok (B.append buf nextChunk) ()
getAll :: Parser ()
getAll = Parser $ \buf err ok -> ParseMore $ \nextChunk ->
if B.null nextChunk
then ok buf ()
else runParser getAll (B.append buf nextChunk) err ok
flushAll :: Parser ()
flushAll = Parser $ \buf err ok -> ParseMore $ \nextChunk ->
if B.null nextChunk
then ok buf ()
else runParser getAll B.empty err ok
------------------------------------------------------------
-- | Get the next byte from the parser
anyByte :: Parser Word8
anyByte = Parser $ \buf err ok ->
case B.uncons buf of
Nothing -> runParser (getMore >> anyByte) buf err ok
Just (c1,b2) -> ok b2 c1
-- | Parse a specific byte at current position
--
-- if the byte is different than the expected on,
-- this parser will raise a failure.
byte :: Word8 -> Parser ()
byte w = Parser $ \buf err ok ->
case B.uncons buf of
Nothing -> runParser (getMore >> byte w) buf err ok
Just (c1,b2) | c1 == w -> ok b2 ()
| otherwise -> err buf ("byte " ++ show w ++ " : failed")
-- | Parse a sequence of bytes from current position
--
-- if the following bytes don't match the expected
-- bytestring completely, the parser will raise a failure
bytes :: ByteString -> Parser ()
bytes allExpected = consumeEq allExpected
where errMsg = "bytes " ++ show allExpected ++ " : failed"
-- partially consume as much as possible or raise an error.
consumeEq expected = Parser $ \actual err ok ->
let eLen = B.length expected in
if B.length actual >= eLen
then -- enough data for doing a full match
let (aMatch,aRem) = B.splitAt eLen actual
in if aMatch == expected
then ok aRem ()
else err actual errMsg
else -- not enough data, match as much as we have, and then recurse.
let (eMatch, eRem) = B.splitAt (B.length actual) expected
in if actual == eMatch
then runParser (getMore >> consumeEq eRem) B.empty err ok
else err actual errMsg
------------------------------------------------------------
-- | Take a storable from the current position in the stream
takeStorable :: Storable d
=> Parser d
takeStorable = anyStorable undefined
where
anyStorable :: Storable d => d -> Parser d
anyStorable a = do
(fptr, off, _) <- B.toForeignPtr <$> take (sizeOf a)
return $ unsafePerformIO $ withForeignPtr fptr $ \ptr -> peekByteOff ptr off
-- | Take @n bytes from the current position in the stream
take :: Int -> Parser ByteString
take n = Parser $ \buf err ok ->
if B.length buf >= n
then let (b1,b2) = B.splitAt n buf in ok b2 b1
else runParser (getMore >> take n) buf err ok
-- | Take bytes while the @predicate hold from the current position in the stream
takeWhile :: (Word8 -> Bool) -> Parser ByteString
takeWhile predicate = Parser $ \buf err ok ->
case B.span predicate buf of
(_, b2) | B.null b2 -> runParser (getMore >> takeWhile predicate) buf err ok
(b1, b2) -> ok b2 b1
-- | Take the remaining bytes from the current position in the stream
takeAll :: Parser ByteString
takeAll = Parser $ \buf err ok ->
runParser (getAll >> returnBuffer) buf err ok
where
returnBuffer = Parser $ \buf _ ok -> ok B.empty buf
-- | Skip @n bytes from the current position in the stream
skip :: Int -> Parser ()
skip n = Parser $ \buf err ok ->
if B.length buf >= n
then ok (B.drop n buf) ()
else runParser (getMore >> skip (n - B.length buf)) B.empty err ok
-- | Skip bytes while the @predicate hold from the current position in the stream
skipWhile :: (Word8 -> Bool) -> Parser ()
skipWhile p = Parser $ \buf err ok ->
case B.span p buf of
(_, b2) | B.null b2 -> runParser (getMore >> skipWhile p) B.empty err ok
(_, b2) -> ok b2 ()
-- | Skip all the remaining bytes from the current position in the stream
skipAll :: Parser ()
skipAll = Parser $ \buf err ok -> runParser flushAll buf err ok