path: root/keys.hs

{-# LANGUAGE ViewPatterns  #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE OverloadedStrings #-}
module Main where

import Debug.Trace
import Data.Binary
import Data.OpenPGP
import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString.Lazy.Char8 as Char8
import qualified Data.ByteString      as S
import Control.Monad
import Text.Show.Pretty
import Data.List
import Data.OpenPGP.CryptoAPI
import Data.Ord
import Data.Maybe
import Data.Bits
import qualified Data.Text as T
import Data.Text.Encoding
import qualified Codec.Binary.Base32 as Base32
import qualified Crypto.Hash.SHA1 as SHA1
import Data.Char (toLower)
import qualified Crypto.PubKey.RSA as RSA
import Data.ASN1.Types
import Data.ASN1.Encoding
import Data.ASN1.BinaryEncoding
import System.Console.CmdTheLine as CmdTheLine
import System.Console.CmdTheLine.GetOpt
import System.Console.GetOpt
import Control.Applicative
import System.Environment
import System.Directory
import System.Exit
import ControlMaybe
import Data.Char
import Control.Arrow (second)

data RSAPublicKey = RSAKey MPI MPI

instance ASN1Object RSAPublicKey where
    toASN1 (RSAKey (MPI n) (MPI e))
                  = \xs -> Start Sequence
                         : IntVal n
                         : IntVal e
                         : End Sequence
                         : xs
    fromASN1 (Start Sequence:IntVal modulus:IntVal pubexp:End Sequence:xs) =
        Right (RSAKey (MPI modulus) (MPI pubexp) , xs)
    fromASN1 _ =
        Left "fromASN1: RSAPublicKey: unexpected format"

rsaKeyFromPacket p@(PublicKeyPacket {}) = do
    n <- lookup 'n' $ key p
    e <- lookup 'e' $ key p
    return $ RSAKey n e
rsaKeyFromPacket p@(SecretKeyPacket {}) = do
    n <- lookup 'n' $ key p
    e <- lookup 'e' $ key p
    return $ RSAKey n e
rsaKeyFromPacket _ = Nothing
derRSA rsa = do
    k <- rsaKeyFromPacket rsa
    return $ encodeASN1 DER (toASN1 k [])

getPackets :: IO [Packet]
getPackets = do
    input <- L.getContents
    case decodeOrFail input of
        Right (_,_,Message pkts) -> return pkts
        Left  (_,_,_)            -> return []


isKey (PublicKeyPacket {}) = True
isKey (SecretKeyPacket {}) = True
isKey _                    = False

isUserID (UserIDPacket {}) = True
isUserID _                 = False

isEmbeddedSignature (EmbeddedSignaturePacket {}) = True
isEmbeddedSignature _                            = False

isCertificationSig (CertificationSignature {}) = True
isCertificationSig _                           = True

issuer (IssuerPacket issuer) = Just issuer
issuer _                     = Nothing
backsig (EmbeddedSignaturePacket s) = Just s
backsig _                           = Nothing

isSubkeySignature (SubkeySignature {}) = True
isSubkeySignature _                    = False

usage (NotationDataPacket
        { human_readable = True
        , notation_name  = "usage@"
        , notation_value = u
        }) = Just u
usage _    = Nothing

verifyBindings keys nonkeys = (top ++ filter isSubkeySignature embedded,othersigs)
 where
    verified = do
        sig <- signatures (Message nonkeys)
        let v = verify (Message keys) sig
        guard (not . null $ signatures_over v)
        return v
    (top,othersigs) = partition isSubkeySignature verified
    embedded = do
        sub <- top
        let sigover = signatures_over sub
            unhashed = sigover >>= unhashed_subpackets
            subsigs = mapMaybe backsig unhashed
        sig <- signatures (Message ([topkey sub,subkey sub]++subsigs))
        let v = verify (Message [subkey sub]) sig
        guard (not . null $ signatures_over v)
        return v

grip k = drop 32 $ fingerprint k

smallpr k = drop 24 $ fingerprint k

disjoint_fp ks = {- concatMap group2 $ -} transpose grouped
 where
    grouped    = groupBy samepr . sortBy (comparing smallpr) $ ks
    samepr a b = smallpr a == smallpr b

    {-
    -- useful for testing
    group2 :: [a] -> [[a]]
    group2 (x:y:ys) = [x,y]:group2 ys
    group2 [x]      = [[x]]
    group2 []       = []
    -}

getBindings ::
  [Packet]
  -> 
    ( [([Packet],[SignatureOver])] -- ^ other signatures with key sets
                                   --   that were used for the verifications
    , [(Word8,
       (Packet, Packet),
       [String],
       [SignatureSubpacket],
       [Packet])] -- ^ binding signatures
    )
getBindings pkts = (sigs,bindings)
 where
    (sigs,concat->bindings) = unzip $ do
        let (keys,nonkeys) = partition isKey pkts
        keys <- disjoint_fp keys
        let (bs,sigs) = verifyBindings keys pkts
        return . ((keys,sigs),) $ do
            b <- bs
            i <- map signature_issuer (signatures_over b)
            i <- maybeToList i
            who <- maybeToList $ find_key fingerprint (Message keys) i
            let (code,claimants) = 
                    case () of
                        _ | who == topkey b -> (1,[])
                        _ | who == subkey b -> (2,[])
                        _                   -> (0,[who])
            let hashed = signatures_over b >>= hashed_subpackets
                kind = guard (code==1) >> hashed >>= maybeToList . usage
            return (code,(topkey b,subkey b), kind, hashed,claimants)

accBindings ::
  Bits t =>
  [(t, (Packet, Packet), [a], [a1], [a2])]
  -> [(t, (Packet, Packet), [a], [a1], [a2])]
accBindings bs = as
  where
    gs = groupBy samePair . sortBy (comparing bindingPair) $ bs
    as = map (foldl1 combine) gs
    bindingPair (_,p,_,_,_) = pub2 p
      where
        pub2 (a,b) = (pub a, pub b)
        pub a = fingerprint_material a
    samePair a b = bindingPair a == bindingPair b
    combine (ac,p,akind,ahashed,aclaimaints)
            (bc,_,bkind,bhashed,bclaimaints)
        = (ac .|. bc,p,akind++bkind,ahashed++bhashed,aclaimaints++bclaimaints)


data UserIDRecord = UserIDRecord {
    uid_full :: String,
    uid_realname :: T.Text,
    uid_user :: T.Text,
    uid_subdomain :: T.Text,
    uid_topdomain :: T.Text
}

isBracket '<' = True
isBracket '>' = True
isBracket _   = False

parseUID str = UserIDRecord {
                    uid_full = str,
                    uid_realname = realname,
                    uid_user = user,
                    uid_subdomain = subdomain,
                    uid_topdomain = topdomain
                }
 where
    text = T.pack str
    (T.strip-> realname, T.dropAround isBracket-> email) 
                              = T.break (=='<') text
    (user, T.tail-> hostname) = T.break (=='@') email
    ( T.reverse            -> topdomain,
      T.reverse . T.drop 1 -> subdomain)
                              = T.break (=='.') . T.reverse $ hostname


derToBase32 = map toLower . Base32.encode . S.unpack . SHA1.hashlazy

listKeys pkts = do
    let (certs,bs) = getBindings pkts
        as = accBindings bs
        defaultkind (k:_) hs = k
        defaultkind []    hs = maybe "subkey"
                                     id
                                     ( listToMaybe 
                                     . mapMaybe (fmap usageString . keyflags)
                                     $ hs)
        kinds = map (\(_,_,k,h,_)->defaultkind k h) as
        kindwidth = maximum $ map length kinds
        kindcol = min 20 kindwidth
        code (c,(m,s),_,_,_) = (fingerprint_material m,-c)
        ownerkey (_,(a,_),_,_,_) = a
        sameMaster (ownerkey->a) (ownerkey->b) = fingerprint_material a==fingerprint_material b
        gs = groupBy sameMaster (sortBy (comparing code) as)
    subs <- gs
    let (code,(top,sub), kind, hashed,claimants):_ = subs
        subkeys = do
            (code,(top,sub), kind, hashed,claimants) <- subs
            let ar = case code of
                        0 -> " ??? "
                        1 -> " --> "
                        2 -> " <-- "
                        3 -> " <-> "
                formkind = take kindcol $ defaultkind kind hashed ++ repeat ' '
                -- torhash = maybe "" id $ derToBase32 <$> derRSA sub
            concat  [ " "
                    -- , grip top
                    , ar
                    , formkind 
                    , " "
                    , fingerprint sub 
                    -- , " " ++ torhash
                    , "\n" ]
                -- ++ ppShow hashed
        torkeys = do
            (code,(top,sub), kind, hashed,claimants) <- subs
            guard ("tor" `elem` kind)
            guard (code .&. 0x2 /= 0)
            maybeToList $ derToBase32 <$> derRSA sub
        uid = {- maybe "" id . listToMaybe $ -} do
            (keys,sigs) <- certs
            sig <- sigs
            guard (isCertificationSig sig)
            guard (topkey sig == top)
            sig_over <- signatures_over sig
            guard (join (fmap (find_key smallpr (Message keys)) $ signature_issuer sig_over) == Just top)
            let UserIDPacket uid = user_id sig
                parsed = parseUID uid
                ar = maybe " --> " (const " <-> ") $ do
                        guard (uid_topdomain parsed == "onion" )
                        guard ( uid_realname parsed `elem` ["","Anonymous"])
                        guard (     uid_user parsed == "root" )
                        let subdom0 = L.fromChunks [encodeUtf8 (uid_subdomain parsed)]
                            len = L.length subdom0
                            subdom = Char8.unpack subdom0
                            match = ( (==subdom) . take (fromIntegral len))
                        guard (len >= 16)
                        listToMaybe $ filter match torkeys
            " " ++ ar ++ "@" ++ " " ++ uid_full parsed ++ "\n"
        (_,sigs) = unzip certs
    "master-key " ++ fingerprint top ++ "\n" ++ uid ++"  ...\n" ++ subkeys ++ "\n"
    

data PGPKeyFlags =
    Special
    | Vouch
    | Sign
    | VouchSign
    | Communication
    | VouchCommunication
    | SignCommunication
    | VouchSignCommunication
    | Storage
    | VouchStorage
    | SignStorage
    | VouchSignStorage
    | Encrypt
    | VouchEncrypt
    | SignEncrypt
    | VouchSignEncrypt
 deriving (Eq,Show,Read,Enum)

usageString flgs = 
 case flgs of
    Special -> "special"
    Vouch -> "vouch"
    Sign -> "sign"
    VouchSign -> "vouch-sign"
    Communication -> "communication"
    VouchCommunication -> "vouch-communication"
    SignCommunication -> "sign-communication"
    VouchSignCommunication -> "vouch-sign-communication"
    Storage -> "storage"
    VouchStorage -> "vouch-storage"
    SignStorage -> "sign-storage"
    VouchSignStorage -> "vouch-sign-storage"
    Encrypt -> "encrypt"
    VouchEncrypt -> "vouch-encrypt"
    SignEncrypt -> "sign-encrypt"
    VouchSignEncrypt -> "vouch-sign-encrypt"


keyflags flgs@(KeyFlagsPacket {}) =
    Just . toEnum $
        (   bit 0x1 certify_keys 
        .|. bit 0x2 sign_data
        .|. bit 0x4 encrypt_communication
        .|. bit 0x8 encrypt_storage )     :: Maybe PGPKeyFlags
    -- other flags:
    --  split_key
    --  authentication (ssh-client)
    --  group_key
 where
    bit v f = if f flgs then v else 0
keyflags _ = Nothing


modifyUID (UserIDPacket str) = UserIDPacket str'
 where
    (fstname,rst) = break (==' ') str
    str' = mod fstname ++ rst
    mod "Bob" = "Bob Fucking"
    mod x     = x
modifyUID other              = other

todo = error "unimplemented"

-- TODO: switch to System.Environment.lookupEnv
--       when linking against newer base libraries.
lookupEnv var = 
    handleIO_ (return Nothing) $ fmap Just (getEnv var)

homedir :: Term (IO String)
homedir = envhomedir <$> opt_homedir
 where
    envhomedir opt = do
        gnupghome <- lookupEnv "GNUPGHOME" >>=
                  \d -> return $ d >>= guard . (/="") >> d
        home <- lookupEnv "HOME" >>=
                  \d -> return $ d >>= guard . (/="") >> d
        {-
        home <- flip fmap getHomeDirectory $
                  \d -> fmap (const d) $ guard (d/="")
        -}
        let homegnupg = (++"/.gnupg") <$> home
        return $ maybe "" id (opt `mplus` gnupghome `mplus` homegnupg)

opt_homedir = optDescrToTerm $ Option
                    "" ["homedir"]
                    (ReqArg id "dir")
                    (concat
                        [ "path to pubring.gpg"
                        , " and secring.gpg"
                        , " (default = ${GNUPGHOME:-$HOME/.gnupg})" ])

opt_options =  optDescrToTerm $ Option
                "" ["options"]
                (ReqArg id "file")
                $ concat
                    [ "Read options from file and do not try to read"
                    , " them from the default options file in the"
                    , " homedir (see --homedir). This option is"
                    , " ignored if used in an options file."
                    , " The default options file is the first existing"
                    , " out of keys.conf, gpg.conf-2, and gpg.conf."]

opt_default_key = optDescrToTerm $ Option
                "" ["default-key"]
                (ReqArg id "name")
                $ concat
                    [ "Use name as the default key to sign with. If"
                    , " this option is not used, the default key is"
                    , " the first key found in the secret keyring."]

opt_list_secret_keys = optDescrToTerm $ Option
                "K" ["list-secret-keys"]
                (NoArg ())
                $ concat
                    [ "List all keys from the secret keyrings." ]


unmaybe def = fmap (maybe def id)

opt_secret_keyring = expandPath <$> unmaybe "" opt_homedir <*> prim
 where
    -- TODO: alow multiple instances of --secret-keyring
    --       See: System.Console.CmdTheLine.Arg.vFlagAll
    prim = unmaybe "secring.gpg" . optDescrToTerm $ Option
                "" ["secret-keyring"]
                (ReqArg id "file")
                $ concat
                    [ "Utilize secret keys in the specified file."
                    , "(default: secring.gpg)" ]

expandPath path (c:cs) | c/='/'    = path ++ "/" ++ (c:cs)
                       | otherwise = c:cs
expandPath path []                 = []

secret_packets :: Term (IO Message)
secret_packets = readPacketsFromFile <$> opt_secret_keyring

readPacketsFromFile :: FilePath -> IO Message
readPacketsFromFile fname = do
    input <- L.readFile fname
    return $
      case decodeOrFail input of
        Right (_,_,msg ) -> msg
        Left  (_,_,_)    -> Message []


parseOptionFile fname = do
    xs <- fmap lines (readFile fname)
    let ys = filter notComment xs
        notComment ('#':_) = False
        notComment cs      = not (all isSpace cs)
    return ys

options_from_file :: Term a -> (String,String,Term (Maybe String)) -> ([String],Term (Maybe String)) -> IO [String]
options_from_file term (homevar,appdir,home) (optfile_alts,options_file) = doit
 where
    homedir = envhomedir <$> home
    envhomedir opt = do
        gnupghome <- lookupEnv homevar >>=
                  \d -> return $ d >>= guard . (/="") >> d
        home <- flip fmap getHomeDirectory $
                  \d -> fmap (const d) $ guard (d/="")
        let homegnupg = (++('/':appdir)) <$> home
        return $ (opt `mplus` gnupghome `mplus` homegnupg)

    doit = do
        args <- getArgs
        let wants_help = 
                not . null $ filter cryForHelp args
                        where cryForHelp "--help"    = True
                              cryForHelp "--version" = True
                              cryForHelp x = 
                                and (zipWith (==) x "--help=")
        (o,h) <- do
            val <- unwrap args (liftA2 (,) options_file homedir, defTI)
            case val of
                _ | wants_help -> return (Nothing,Nothing)
                {-
                Left e         -> putStrLn ("Unable to find home directory ")
                                  >> exitFailure
                -}
                Left e -> return (Nothing,Nothing)
                Right (o,h)    -> fmap (o,) h
        ofile <- fmap listToMaybe . flip (maybe (return [])) h $ \h -> 
                let optfiles = map (second ((h++"/")++)) 
                                   (maybe optfile_alts' (:[]) o')
                    optfile_alts' = zip (False:repeat True) optfile_alts
                    o' = fmap (False,) o
                in filterM (doesFileExist . snd) optfiles
        args <- flip (maybe $ return args) ofile $ \(forgive,fname) -> do
            let h' = fromJust h
            newargs <- (:) <$> pure ("homedir "++h') <*> parseOptionFile fname
            let toArgs = toHead ("--"++) . words
                toHead f (x:xs) = f x : xs
                toHead f []     = []
                voidTerm = fmap (const ())
                appendArgs as [] = return as
                appendArgs as (configline:cs) = do
                    let xs = toArgs configline
                    w <-unwrap (xs++as) (voidTerm term,defTI)
                    case w of
                        Left  _ -> appendArgs as cs
                        Right _ -> appendArgs (xs++as) cs
            -- TODO: check errors if forgive = False
            appendArgs args newargs
        return args

runWithOptionsFile (term,ti) = do
    as <- options_from_file term
                            ("GNUPGHOME",".gnupg",opt_homedir)
                            (["keys.conf","gpg.conf-2","gpg.conf"]
                            ,opt_options)
    q <- eval as (term , ti)
    q

main = do
    q <- runWithOptionsFile (listSecretKeys, defTI { termName = "keys", CmdTheLine.version = "0.1" })
    return ()
 where
    -- showhome =  flip const <$> opt_options <*> ( (>>= putStrLn) <$> homedir )
    showhome =  opt_default_key <:> opt_options <:> ( (>>= putStrLn) <$> homedir )
    a <:> b = flip const <$> a <*> b
    infixr 2 <:>

    listSecretKeys = opt_options <:> (>>= list) <$> secret_packets

    list (Message pkts) = putStrLn $ listKeys pkts