Unix.hsc

{-# LANGUAGE CPP #-}

#include "HsNet.h"
##include "HsNetDef.h"

module Network.Socket.Unix (
    isUnixDomainSocketAvailable
  , socketPair
  , sendFd
  , recvFd
  , getPeerCredential
  , getPeerCred
  , getPeerEid
  ) where

import System.Posix.Types (Fd(..))

import Network.Socket.Buffer
import Network.Socket.Imports
import Network.Socket.Posix.Cmsg
import Network.Socket.Types

#if defined(HAVE_GETPEEREID)
import System.IO.Error (catchIOError)
#endif
#ifdef HAVE_GETPEEREID
import Foreign.Marshal.Alloc (alloca)
#endif
#ifdef DOMAIN_SOCKET_SUPPORT
import Foreign.Marshal.Alloc (allocaBytes)
import Foreign.Marshal.Array (peekArray)

import Network.Socket.Fcntl
import Network.Socket.Internal
#endif
#ifdef HAVE_STRUCT_UCRED_SO_PEERCRED
import Network.Socket.Options
#endif

-- | Getting process ID, user ID and group ID for UNIX-domain sockets.
--
--   This is implemented with SO_PEERCRED on Linux and getpeereid()
--   on BSD variants. Unfortunately, on some BSD variants
--   getpeereid() returns unexpected results, rather than an error,
--   for AF_INET sockets. It is the user's responsibility to make sure
--   that the socket is a UNIX-domain socket.
--   Also, on some BSD variants, getpeereid() does not return credentials
--   for sockets created via 'socketPair', only separately created and then
--   explicitly connected UNIX-domain sockets work on such systems.
--
--   Since 2.7.0.0.
getPeerCredential :: Socket -> IO (Maybe CUInt, Maybe CUInt, Maybe CUInt)
#ifdef HAVE_STRUCT_UCRED_SO_PEERCRED
getPeerCredential sock = do
    (pid, uid, gid) <- getPeerCred sock
    if uid == maxBound then
        return (Nothing, Nothing, Nothing)
      else
        return (Just pid, Just uid, Just gid)
#elif defined(HAVE_GETPEEREID)
getPeerCredential sock =
    go `catchIOError` \_ -> return (Nothing,Nothing,Nothing)
  where
    go = do
        (uid, gid) <- getPeerEid sock
        return (Nothing, Just uid, Just gid)
#else
getPeerCredential _ = return (Nothing, Nothing, Nothing)
#endif

-- | Returns the processID, userID and groupID of the peer of
--   a UNIX-domain socket.
--
-- Only available on platforms that support SO_PEERCRED.
getPeerCred :: Socket -> IO (CUInt, CUInt, CUInt)
#ifdef HAVE_STRUCT_UCRED_SO_PEERCRED
getPeerCred s = do
    let opt = SockOpt (#const SOL_SOCKET) (#const SO_PEERCRED)
    PeerCred cred <- getSockOpt s opt
    return cred

newtype PeerCred = PeerCred (CUInt, CUInt, CUInt)
instance Storable PeerCred where
    sizeOf    _ = (#const sizeof(struct ucred))
    alignment _ = alignment (0 :: CInt)
    poke _ _ = return ()
    peek p = do
        pid <- (#peek struct ucred, pid) p
        uid <- (#peek struct ucred, uid) p
        gid <- (#peek struct ucred, gid) p
        return $ PeerCred (pid, uid, gid)
#else
getPeerCred _ = return (0, 0, 0)
#endif
{-# Deprecated getPeerCred "Use getPeerCredential instead" #-}

-- | Returns the userID and groupID of the peer of
--   a UNIX-domain socket.
--
--  Only available on platforms that support getpeereid().
getPeerEid :: Socket -> IO (CUInt, CUInt)
#ifdef HAVE_GETPEEREID
getPeerEid s = do
  alloca $ \ ptr_uid ->
    alloca $ \ ptr_gid -> do
      withFdSocket s $ \fd ->
        throwSocketErrorIfMinus1Retry_ "Network.Socket.getPeerEid" $
          c_getpeereid fd ptr_uid ptr_gid
      uid <- peek ptr_uid
      gid <- peek ptr_gid
      return (uid, gid)

foreign import CALLCONV unsafe "getpeereid"
  c_getpeereid :: CInt -> Ptr CUInt -> Ptr CUInt -> IO CInt
#else
getPeerEid _ = return (0, 0)
#endif

{-# Deprecated getPeerEid "Use getPeerCredential instead" #-}

-- | Whether or not UNIX-domain sockets are available.
--
--   Since 2.7.0.0.
isUnixDomainSocketAvailable :: Bool
#if defined(DOMAIN_SOCKET_SUPPORT)
isUnixDomainSocketAvailable = True
#else
isUnixDomainSocketAvailable = False
#endif

data NullSockAddr = NullSockAddr

instance SocketAddress NullSockAddr where
    sizeOfSocketAddress _ = 0
    peekSocketAddress _   = return NullSockAddr
    pokeSocketAddress _ _ = return ()

-- | Send a file descriptor over a UNIX-domain socket.
--   Use this function in the case where 'isUnixDomainSocketAvailable' is
--  'True'.
sendFd :: Socket -> CInt -> IO ()
#if defined(DOMAIN_SOCKET_SUPPORT)
sendFd s outfd = void $ allocaBytes dummyBufSize $ \buf -> do
    let cmsg = encodeCmsg $ Fd outfd
    sendBufMsg s NullSockAddr [(buf,dummyBufSize)] [cmsg] mempty
  where
    dummyBufSize = 1
#else
sendFd _ _ = error "Network.Socket.sendFd"
#endif

-- | Receive a file descriptor over a UNIX-domain socket. Note that the resulting
--   file descriptor may have to be put into non-blocking mode in order to be
--   used safely. See 'setNonBlockIfNeeded'.
--   Use this function in the case where 'isUnixDomainSocketAvailable' is
--  'True'.
recvFd :: Socket -> IO CInt
#if defined(DOMAIN_SOCKET_SUPPORT)
recvFd s = allocaBytes dummyBufSize $ \buf -> do
    (NullSockAddr, _, cmsgs, _) <- recvBufMsg s [(buf,dummyBufSize)] 32 mempty
    case (lookupCmsg CmsgIdFd cmsgs >>= decodeCmsg) :: Maybe Fd of
      Nothing      -> return (-1)
      Just (Fd fd) -> return fd
  where
    dummyBufSize = 16
#else
recvFd _ = error "Network.Socket.recvFd"
#endif

-- | Build a pair of connected socket objects.
--   For portability, use this function in the case
--   where 'isUnixDomainSocketAvailable' is 'True'
--   and specify 'AF_UNIX' to the first argument.
socketPair :: Family              -- Family Name (usually AF_UNIX)
           -> SocketType          -- Socket Type (usually Stream)
           -> ProtocolNumber      -- Protocol Number
           -> IO (Socket, Socket) -- unnamed and connected.
#if defined(DOMAIN_SOCKET_SUPPORT)
socketPair family stype protocol =
    allocaBytes (2 * sizeOf (1 :: CInt)) $ \ fdArr -> do
      let c_stype = packSocketType stype
      _rc <- throwSocketErrorIfMinus1Retry "Network.Socket.socketpair" $
                  c_socketpair (packFamily family) c_stype protocol fdArr
      [fd1,fd2] <- peekArray 2 fdArr
      setNonBlockIfNeeded fd1
      setNonBlockIfNeeded fd2
      s1 <- mkSocket fd1
      s2 <- mkSocket fd2
      return (s1, s2)

foreign import ccall unsafe "socketpair"
  c_socketpair :: CInt -> CInt -> CInt -> Ptr CInt -> IO CInt
#else
socketPair _ _ _ = error "Network.Socket.socketPair"
#endif