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git-annex/Types/Key.hs
Yaroslav Halchenko 0151976676
Typo fix unncessary -> unnecessary. 
Detected while reading recent CHANGELOG entry but then decided to apply
to entire codebase and docs since why not?
2022-08-20 09:40:19 -04:00

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{- git-annex Key data type
-
- Copyright 2011-2020 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE OverloadedStrings, DeriveGeneric #-}
module Types.Key (
KeyData(..),
Key,
fromKey,
keyData,
mkKey,
alterKey,
isKeyPrefix,
splitKeyNameExtension,
keyParser,
keySerialization,
AssociatedFile(..),
KeyVariety(..),
HasExt(..),
HashSize(..),
hasExt,
sameExceptExt,
formatKeyVariety,
parseKeyVariety,
) where
import qualified Data.ByteString as S
import qualified Data.ByteString.Short as S (ShortByteString, toShort, fromShort)
import qualified Data.ByteString.Char8 as S8
import qualified Data.ByteString.Lazy as L
import Data.ByteString.Builder
import Data.ByteString.Builder.Extra
import qualified Data.Attoparsec.ByteString as A
import qualified Data.Attoparsec.ByteString.Char8 as A8
import Utility.FileSystemEncoding
import Data.List
import Data.Char
import System.Posix.Types
import Foreign.C.Types
import Data.Monoid
import Control.Applicative
import GHC.Generics
import Control.DeepSeq
import Prelude
{- A Key has a unique name, which is derived from a particular backend,
- and may contain other optional metadata. -}
data KeyData = Key
{ keyName :: S.ShortByteString
, keyVariety :: KeyVariety
, keySize :: Maybe Integer
, keyMtime :: Maybe EpochTime
, keyChunkSize :: Maybe Integer
, keyChunkNum :: Maybe Integer
} deriving (Eq, Ord, Read, Show, Generic)
instance NFData KeyData
{- Caching the seralization of a key is an optimization.
-
- This constructor is not exported, and all smart constructors maintain
- the serialization.
-}
data Key = MkKey
{ keyData :: KeyData
, keySerialization :: S.ShortByteString
} deriving (Show, Generic)
instance Eq Key where
-- comparing the serialization would be unnecessary work
a == b = keyData a == keyData b
instance Ord Key where
compare a b = compare (keyData a) (keyData b)
instance NFData Key
{- Access a field of data from the KeyData. -}
{-# INLINE fromKey #-}
fromKey :: (KeyData -> a) -> Key -> a
fromKey f = f . keyData
{- Smart constructor for a Key. The provided KeyData has all values empty. -}
mkKey :: (KeyData -> KeyData) -> Key
mkKey f =
let d = f stub
in MkKey d (mkKeySerialization d)
where
stub = Key
{ keyName = mempty
, keyVariety = OtherKey mempty
, keySize = Nothing
, keyMtime = Nothing
, keyChunkSize = Nothing
, keyChunkNum = Nothing
}
{- Alter a Key's data. -}
alterKey :: Key -> (KeyData -> KeyData) -> Key
alterKey k f =
let d = f (keyData k)
in MkKey d (mkKeySerialization d)
-- Checks if a string looks like at least the start of a key.
isKeyPrefix :: String -> Bool
isKeyPrefix s = [fieldSep, fieldSep] `isInfixOf` s
fieldSep :: Char
fieldSep = '-'
mkKeySerialization :: KeyData -> S.ShortByteString
mkKeySerialization = S.toShort . L.toStrict
. toLazyByteStringWith (safeStrategy 128 smallChunkSize) L.empty
. buildKeyData
{- Builds a ByteString from a KeyData.
-
- The name field is always shown last, separated by doubled fieldSeps,
- and is the only field allowed to contain the fieldSep.
-}
buildKeyData :: KeyData -> Builder
buildKeyData k = byteString (formatKeyVariety (keyVariety k))
<> 's' ?: (integerDec <$> keySize k)
<> 'm' ?: (integerDec . (\(CTime t) -> fromIntegral t) <$> keyMtime k)
<> 'S' ?: (integerDec <$> keyChunkSize k)
<> 'C' ?: (integerDec <$> keyChunkNum k)
<> sepbefore (sepbefore (shortByteString (keyName k)))
where
sepbefore s = char7 fieldSep <> s
c ?: (Just b) = sepbefore (char7 c <> b)
_ ?: Nothing = mempty
{- This is a strict parser for security reasons; a key
- can contain only 4 fields, which all consist only of numbers.
- Any key containing other fields, or non-numeric data will fail
- to parse.
-
- If a key contained non-numeric fields, they could be used to
- embed data used in a SHA1 collision attack, which would be a
- problem since the keys are committed to git.
-}
keyParser :: A.Parser Key
keyParser = do
-- key variety cannot be empty
v <- (parseKeyVariety <$> A8.takeWhile1 (/= fieldSep))
s <- parsesize
m <- parsemtime
cs <- parsechunksize
cn <- parsechunknum
_ <- A8.char fieldSep
_ <- A8.char fieldSep
n <- A.takeByteString
if validKeyName v n
then
let d = Key
{ keyName = S.toShort n
, keyVariety = v
, keySize = s
, keyMtime = m
, keyChunkSize = cs
, keyChunkNum = cn
}
in pure $ MkKey d (mkKeySerialization d)
else fail "invalid keyName"
where
parseopt p = (Just <$> (A8.char fieldSep *> p)) <|> pure Nothing
parsesize = parseopt $ A8.char 's' *> A8.decimal
parsemtime = parseopt $ CTime <$> (A8.char 'm' *> A8.decimal)
parsechunksize = parseopt $ A8.char 'S' *> A8.decimal
parsechunknum = parseopt $ A8.char 'C' *> A8.decimal
{- Limits the length of the extension in the keyName to mitigate against
- SHA1 collision attacks.
-
- In such an attack, the extension of the key could be made to contain
- the collision generation data, with the result that a signed git commit
- including such keys would not be secure.
-
- The maximum extension length ever generated for such a key was 8
- characters, but they may be unicode which could use up to 4 bytes each,
- so 32 bytes. 64 bytes is used here to give a little future wiggle-room.
- The SHA1 common-prefix attack needs 128 bytes of data.
-}
validKeyName :: KeyVariety -> S.ByteString -> Bool
validKeyName kv name
| hasExt kv =
let ext = snd $ splitKeyNameExtension' name
in S.length ext <= 64
| otherwise = True
{- This splits any extension out of the keyName, returning the
- keyName minus extension, and the extension (including leading dot).
-}
splitKeyNameExtension :: Key -> (S.ByteString, S.ByteString)
splitKeyNameExtension = splitKeyNameExtension' . S.fromShort . keyName . keyData
splitKeyNameExtension' :: S.ByteString -> (S.ByteString, S.ByteString)
splitKeyNameExtension' keyname = S8.span (/= '.') keyname
{- A filename may be associated with a Key. -}
newtype AssociatedFile = AssociatedFile (Maybe RawFilePath)
deriving (Show, Read, Eq, Ord)
{- There are several different varieties of keys. -}
data KeyVariety
= SHA2Key HashSize HasExt
| SHA3Key HashSize HasExt
| SKEINKey HashSize HasExt
| Blake2bKey HashSize HasExt
| Blake2bpKey HashSize HasExt
| Blake2sKey HashSize HasExt
| Blake2spKey HashSize HasExt
| SHA1Key HasExt
| MD5Key HasExt
| WORMKey
| URLKey
-- A key that is handled by some external backend.
| ExternalKey S.ByteString HasExt
-- Some repositories may contain keys of other varieties,
-- which can still be processed to some extent.
| OtherKey S.ByteString
deriving (Eq, Ord, Read, Show, Generic)
instance NFData KeyVariety
{- Some varieties of keys may contain an extension at the end of the
- keyName -}
newtype HasExt = HasExt Bool
deriving (Eq, Ord, Read, Show, Generic)
instance NFData HasExt
newtype HashSize = HashSize Int
deriving (Eq, Ord, Read, Show, Generic)
instance NFData HashSize
hasExt :: KeyVariety -> Bool
hasExt (SHA2Key _ (HasExt b)) = b
hasExt (SHA3Key _ (HasExt b)) = b
hasExt (SKEINKey _ (HasExt b)) = b
hasExt (Blake2bKey _ (HasExt b)) = b
hasExt (Blake2bpKey _ (HasExt b)) = b
hasExt (Blake2sKey _ (HasExt b)) = b
hasExt (Blake2spKey _ (HasExt b)) = b
hasExt (SHA1Key (HasExt b)) = b
hasExt (MD5Key (HasExt b)) = b
hasExt WORMKey = False
hasExt URLKey = False
hasExt (ExternalKey _ (HasExt b)) = b
hasExt (OtherKey s) = (snd <$> S8.unsnoc s) == Just 'E'
sameExceptExt :: KeyVariety -> KeyVariety -> Bool
sameExceptExt (SHA2Key sz1 _) (SHA2Key sz2 _) = sz1 == sz2
sameExceptExt (SHA3Key sz1 _) (SHA3Key sz2 _) = sz1 == sz2
sameExceptExt (SKEINKey sz1 _) (SKEINKey sz2 _) = sz1 == sz2
sameExceptExt (Blake2bKey sz1 _) (Blake2bKey sz2 _) = sz1 == sz2
sameExceptExt (Blake2bpKey sz1 _) (Blake2bpKey sz2 _) = sz1 == sz2
sameExceptExt (Blake2sKey sz1 _) (Blake2sKey sz2 _) = sz1 == sz2
sameExceptExt (Blake2spKey sz1 _) (Blake2spKey sz2 _) = sz1 == sz2
sameExceptExt (SHA1Key _) (SHA1Key _) = True
sameExceptExt (MD5Key _) (MD5Key _) = True
sameExceptExt _ _ = False
formatKeyVariety :: KeyVariety -> S.ByteString
formatKeyVariety v = case v of
SHA2Key sz e -> adde e (addsz sz "SHA")
SHA3Key sz e -> adde e (addsz sz "SHA3_")
SKEINKey sz e -> adde e (addsz sz "SKEIN")
Blake2bKey sz e -> adde e (addsz sz "BLAKE2B")
Blake2bpKey sz e -> adde e (addsz sz "BLAKE2BP")
Blake2sKey sz e -> adde e (addsz sz "BLAKE2S")
Blake2spKey sz e -> adde e (addsz sz "BLAKE2SP")
SHA1Key e -> adde e "SHA1"
MD5Key e -> adde e "MD5"
WORMKey -> "WORM"
URLKey -> "URL"
ExternalKey s e -> adde e ("X" <> s)
OtherKey s -> s
where
adde (HasExt False) s = s
adde (HasExt True) s = s <> "E"
addsz (HashSize n) s = s <> case n of
256 -> "256"
512 -> "512"
224 -> "224"
384 -> "384"
160 -> "160"
-- This is relatively slow, which is why the common hash
-- sizes are hardcoded above.
_ -> S8.pack (show n)
parseKeyVariety :: S.ByteString -> KeyVariety
parseKeyVariety "SHA256" = SHA2Key (HashSize 256) (HasExt False)
parseKeyVariety "SHA256E" = SHA2Key (HashSize 256) (HasExt True)
parseKeyVariety "SHA512" = SHA2Key (HashSize 512) (HasExt False)
parseKeyVariety "SHA512E" = SHA2Key (HashSize 512) (HasExt True)
parseKeyVariety "SHA224" = SHA2Key (HashSize 224) (HasExt False)
parseKeyVariety "SHA224E" = SHA2Key (HashSize 224) (HasExt True)
parseKeyVariety "SHA384" = SHA2Key (HashSize 384) (HasExt False)
parseKeyVariety "SHA384E" = SHA2Key (HashSize 384) (HasExt True)
parseKeyVariety "SHA3_512" = SHA3Key (HashSize 512) (HasExt False)
parseKeyVariety "SHA3_512E" = SHA3Key (HashSize 512) (HasExt True)
parseKeyVariety "SHA3_384" = SHA3Key (HashSize 384) (HasExt False)
parseKeyVariety "SHA3_384E" = SHA3Key (HashSize 384) (HasExt True)
parseKeyVariety "SHA3_256" = SHA3Key (HashSize 256) (HasExt False)
parseKeyVariety "SHA3_256E" = SHA3Key (HashSize 256) (HasExt True)
parseKeyVariety "SHA3_224" = SHA3Key (HashSize 224) (HasExt False)
parseKeyVariety "SHA3_224E" = SHA3Key (HashSize 224) (HasExt True)
parseKeyVariety "SKEIN512" = SKEINKey (HashSize 512) (HasExt False)
parseKeyVariety "SKEIN512E" = SKEINKey (HashSize 512) (HasExt True)
parseKeyVariety "SKEIN256" = SKEINKey (HashSize 256) (HasExt False)
parseKeyVariety "SKEIN256E" = SKEINKey (HashSize 256) (HasExt True)
parseKeyVariety "BLAKE2B160" = Blake2bKey (HashSize 160) (HasExt False)
parseKeyVariety "BLAKE2B160E" = Blake2bKey (HashSize 160) (HasExt True)
parseKeyVariety "BLAKE2B224" = Blake2bKey (HashSize 224) (HasExt False)
parseKeyVariety "BLAKE2B224E" = Blake2bKey (HashSize 224) (HasExt True)
parseKeyVariety "BLAKE2B256" = Blake2bKey (HashSize 256) (HasExt False)
parseKeyVariety "BLAKE2B256E" = Blake2bKey (HashSize 256) (HasExt True)
parseKeyVariety "BLAKE2B384" = Blake2bKey (HashSize 384) (HasExt False)
parseKeyVariety "BLAKE2B384E" = Blake2bKey (HashSize 384) (HasExt True)
parseKeyVariety "BLAKE2B512" = Blake2bKey (HashSize 512) (HasExt False)
parseKeyVariety "BLAKE2B512E" = Blake2bKey (HashSize 512) (HasExt True)
parseKeyVariety "BLAKE2BP512" = Blake2bpKey (HashSize 512) (HasExt False)
parseKeyVariety "BLAKE2BP512E" = Blake2bpKey (HashSize 512) (HasExt True)
parseKeyVariety "BLAKE2S160" = Blake2sKey (HashSize 160) (HasExt False)
parseKeyVariety "BLAKE2S160E" = Blake2sKey (HashSize 160) (HasExt True)
parseKeyVariety "BLAKE2S224" = Blake2sKey (HashSize 224) (HasExt False)
parseKeyVariety "BLAKE2S224E" = Blake2sKey (HashSize 224) (HasExt True)
parseKeyVariety "BLAKE2S256" = Blake2sKey (HashSize 256) (HasExt False)
parseKeyVariety "BLAKE2S256E" = Blake2sKey (HashSize 256) (HasExt True)
parseKeyVariety "BLAKE2SP224" = Blake2spKey (HashSize 224) (HasExt False)
parseKeyVariety "BLAKE2SP224E" = Blake2spKey (HashSize 224) (HasExt True)
parseKeyVariety "BLAKE2SP256" = Blake2spKey (HashSize 256) (HasExt False)
parseKeyVariety "BLAKE2SP256E" = Blake2spKey (HashSize 256) (HasExt True)
parseKeyVariety "SHA1" = SHA1Key (HasExt False)
parseKeyVariety "SHA1E" = SHA1Key (HasExt True)
parseKeyVariety "MD5" = MD5Key (HasExt False)
parseKeyVariety "MD5E" = MD5Key (HasExt True)
parseKeyVariety "WORM" = WORMKey
parseKeyVariety "URL" = URLKey
parseKeyVariety b
| "X" `S.isPrefixOf` b =
let b' = S.tail b
in if not (S.null b') && S.last b' == fromIntegral (ord 'E')
then ExternalKey (S.init b') (HasExt True)
else ExternalKey b' (HasExt False)
| otherwise = OtherKey b
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