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path: root/Presence/LocalPeerCred.hs
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{-# LANGUAGE ViewPatterns  #-}
{-# LANGUAGE TupleSections #-}
module LocalPeerCred where

import System.Endian
import qualified Data.ByteString.Lazy.Char8 as L
 -- hiding (map,putStrLn,tail,splitAt,tails,filter)
 --  import qualified Data.ByteString.Lazy.Char8 as L (splitAt)
import qualified Data.ByteString.Lazy as W8
import Data.List as List (tails,groupBy)
import System.IO ( withFile, IOMode(..))
import System.Directory
import Control.Arrow (first)
import Data.Char
import Data.Maybe
import Data.Binary
import Data.Bits
import System.Posix.Types
import System.Posix.Files
import Debug.Trace
import SocketLike
import ControlMaybe

xs     ?? n | n < 0 =  Nothing
[]     ?? _         =  Nothing
(x:_)  ?? 0         =  Just x
(_:xs) ?? n         =  xs ?? (n-1)

parseHex bs = L.concat . parseHex' $ bs
 where
  parseHex' bs =
      let (dnib,ts) = L.splitAt 2 bs
          parseNibble x = W8.pack $ group2 toW8 (W8.unpack $ W8.map hexDigit x)
          hexDigit d = d - (if d>0x39 then 0x37 else 0x30)
          group2 f (x:y:ys) = f x y : group2 f ys
          group2 _ _        = []
          toW8 a b = shift a 4 .|. b
      in parseNibble dnib :
          if L.null ts 
              then []
              else parseHex' ts

getLocalPeerCred' (unmap6mapped4 -> SockAddrInet portn host) = do
    let port = fromEnum portn
    {- trace ("tcp4 "++show(port,host)) $ -} 
    withFile "/proc/net/tcp"  ReadMode (parseProcNet port host)

getLocalPeerCred' (unmap6mapped4 -> SockAddrInet6 portn flow host scope) = do
    let port = fromEnum portn
        (a,b,c,d) = host
        host' = (toBE32 a, toBE32 b, toBE32 c, toBE32 d)
    withFile "/proc/net/tcp6" ReadMode (parseProcNet port host')

getLocalPeerCred' (unmap6mapped4 -> addr@(SockAddrUnix _)) =
    -- TODO:  parse /proc/net/unix
    -- see also: Network.Socket.getPeerCred
    return Nothing

getLocalPeerCred sock = do
    addr <- getPeerName sock
    muid <- getLocalPeerCred' addr
    case muid of
        Just (uid,inode) -> return (Just uid)
        Nothing  -> trace "proc failed." $ fmap (validate . CUid . fromIntegral . sndOf3) (getPeerCred sock)
                     where sndOf3 (pid,uid,gid) = uid
 where
    validate uid = Just uid -- TODO

from16 :: Word16 -> Int
from16 = fromEnum

as16 :: Word16 -> Word16
as16 = id

parseProcNet port host h = do
        tcp <- L.hGetContents h -- Failed: tcp <- hFileSize h >>= hGet h . fromIntegral
        let u = do
                    ls <- listToMaybe . tail . tails . L.lines $ tcp
                    let ws = map L.words ls
                    let rs = ( catMaybes . flip map ws $ \xs -> do
                          let ys = snd (Prelude.splitAt 1 xs)
                          localaddr <- listToMaybe ys
                          let zs = L.splitWith (==':') localaddr
                          addr <- fmap parseHex $ listToMaybe zs
                          port <- fmap (fromIntegral . as16 . decode . parseHex) $ listToMaybe $ snd (Prelude.splitAt 1 zs)
                          let ys' = snd (Prelude.splitAt 5 (tail ys))
                              ys'' = snd (Prelude.splitAt 2 ys')
                          uid <- listToMaybe ys'
                          inode <- listToMaybe ys''
                          let peer = (port,decode addr)
                              user = toEnum (read (L.unpack uid) ::Int) ::UserID  -- CUid . fromIntegral $ (read (unpack uid)::Int)
                          return $ {-trace ("peer:"++show(peer,user,inode))-} (peer,(user,inode))
                          )
                    fmap snd . listToMaybe $ filter ((==(port,host)).fst) rs 
        {- trace ("found: "++show u) -} 
        u `seq` return u
 {-
 where
    a === b = let r= a==b in  trace ("Comparing "++show (a,b)++"-->"++show r) r
    -}


-- PEER NAME: [::ffff:127.0.0.1]:34307
unmap6mapped4 addr@(SockAddrInet6 port _ (0,0,0xFFFF,a) _) = SockAddrInet port (toBE32 a)
unmap6mapped4 addr = addr

identifyTTY tty_pids uid inode = do
    pid <- scanProc (show uid) (L.unpack inode)
    -- putStrLn $ "scanProc --> "++show pid
    flip (maybe (return Nothing)) pid $ \(pid,ttydev) -> do
    tty <- ttyOrDisplay pid ttydev
    -- putStrLn $ "users = " ++ show tty_pids
    dts <- ttyToXorgs tty_pids
    -- putStrLn $ "displays = " ++ show dts 
    -- putStrLn $ "tty = " ++ show tty
    -- -- displays = [(":5",Chunk "tty7" Empty)]
    let tty' = if take 3 tty=="tty" then Just (L.pack tty) else lookup (parseTty tty) (map (first parseTty) dts)
    return tty'
    where
        parseTty :: String -> Float
        parseTty = read .  tail . dropWhile (/=':') 

ttyToXorgs tty_pids = do
    dts' <- flip mapM tty_pids $ \(tty,pid) -> do
        cmd' <- readFile $ "/proc/"++show pid++"/cmdline"
        case listToMaybe . words . takeWhile (/='\0') $ cmd' of
          Nothing  -> return Nothing
          Just cmd -> do
            if notElem cmd ["gdm-session-worker"]
                then return Nothing
                else do
                  display <- readDisplayVariable pid
                  return (fmap ( (,tty) . snd ) display)
    let dts = catMaybes dts'
    return dts


scanProc uid inode = do
    contents <- getDirectoryContents "/proc" `catchIO_` return []
    let pids = reverse $ filter (\n -> not (null n) && isDigit (head n)) contents
    let searchPids []         = return Nothing
        searchPids (pid:pids) =  do
            loginuid <- fmap makeUidStr $ readFile $ "/proc/"++pid++"/loginuid"
            if False -- (uid/=loginuid) -- this check proved bad when mcabber ran on tty3
             then searchPids pids
             else do
                -- putStrLn $ "pid "++show pid ++ " --> uid "++show loginuid
                let loop [] = return Nothing
                    loop ("0":fds) = loop fds
                    loop (fd:fds) = do
                      handleIO_ (loop fds) $ do
                          what <- readSymbolicLink $ "/proc/"++pid++"/fd/"++fd
                          -- putStrLn $ " what= "++show what
                          if (what=="socket:["++inode++"]")
                            then do
                              tty <- readSymbolicLink $ "/proc/"++pid++"/fd/0"
                              return (Just (pid,tty))
                            else loop fds
                fds <- getDirectoryContents ("/proc/"++pid++"/fd") `catchIO_` return []
                mb <- loop fds
                maybe (searchPids pids) (return . Just) mb

    fmap (fmap (first (read :: String -> CPid))) $ searchPids pids

ttyOrDisplay pid ttydev = do
    ptty <- searchParentsForTTY (show pid) ttydev
    case ptty of
        Just tty -> return tty
        Nothing  -> do
            display <- readDisplayVariable pid
            -- putStrLn $ "display = " ++ show display
            case display of
                Just (_,disp) -> return disp
                _             -> return ttydev


readDisplayVariable pid = do
            env <- handleIO_ (return "") 
                    . readFile $ "/proc/"++show pid++"/environ"
            let vs = unzero $ List.groupBy (\_ c->c/='\0') env
                unzero []     = []
                unzero (v:vs) = v:map tail vs
                keyvalue xs = (key,value) 
                  where
                    (key,ys) = break (=='=') xs
                    value = case ys of { [] -> [];  (_:ys') -> ys' }
                display = listToMaybe 
                            . filter ((=="DISPLAY").fst) 
                            . map keyvalue 
                            $ vs
            return display 


makeUidStr "4294967295" = "invalid"
makeUidStr uid          = uid


searchParentsForTTY pid  ttydev | take 8 ttydev == "/dev/tty" = return . Just $ drop 5 ttydev
searchParentsForTTY "1"  ttydev | otherwise                   = return Nothing
searchParentsForTTY pid ttydev = do
    stat <- handleIO_ (return "") . readFile $ "/proc/"++pid++"/stat"
    case words stat ?? 3 of
        Nothing   -> return Nothing
        Just ppid -> do
          tty <- handleIO_ (return "") $ readSymbolicLink $ "/proc/"++ppid++"/fd/0"
          searchParentsForTTY ppid tty