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{- -*- haskell -*- -}
-- |HsOpenSSL is an OpenSSL binding for Haskell. It can generate RSA
-- and DSA keys, read and write PEM files, generate message digests,
-- sign and verify messages, encrypt and decrypt messages.
--
-- Please note that this project has started at the time when there
-- were no pure-Haskell implementations of TLS. Now there is tls
-- package (<http://hackage.haskell.org/package/tls>), which looks
-- pretty saner than HsOpenSSL especially for initialisation and error
-- handlings. So PHO (the initial author of HsOpenSSL) wants to
-- encourage you to use and improve the tls package instead as long as
-- possible. The only problem is that the tls package has not received
-- as much review as OpenSSL from cryptography specialists yet, thus
-- we can't assume it's secure enough.
--
-- Features that aren't (yet) supported:
--
-- [/SSL network connection/] ssl(3) functionalities aren't fully
-- covered yet. See "OpenSSL.Session".
--
-- [/Complete coverage of Low-level API to symmetric ciphers/] Only
-- high-level APIs (EVP and BIO) are fully available. But I believe
-- no one will be lost without functions like @DES_set_odd_parity@.
--
-- [/Low-level API to asymmetric ciphers/] Only a high-level API
-- (EVP) is available. But I believe no one will complain about the
-- absence of functions like @RSA_public_encrypt@.
--
-- [/Key generation of Diffie-Hellman algorithm/] Only RSA and DSA
-- keys can currently be generated.
--
-- [/X.509 v3 extension handling/] It should be supported in the
-- future.
--
-- [/Low-level API to message digest functions/] Just use EVP
-- instead of something like @MD5_Update@.
--
-- [/API to PKCS#12 functionality/] It should be covered someday.
--
-- [/BIO/] BIO isn't needed because we are Haskell hackers. Though
-- HsOpenSSL itself uses BIO internally.
--
-- [/ENGINE cryptographic module/] The default implementations work
-- very well, don't they?
#include "HsOpenSSL.h"
module OpenSSL
( withOpenSSL
)
where
import Control.Concurrent.MVar
import Control.Monad
import OpenSSL.SSL
import System.IO.Unsafe
#if !MIN_VERSION_base(4,6,0)
import Control.Exception (onException, mask_)
#endif
foreign import ccall "HsOpenSSL_setupMutex"
setupMutex :: IO ()
-- |Computation of @'withOpenSSL' action@ initializes the OpenSSL
-- library as necessary, and computes @action@. Every application that
-- uses HsOpenSSL must wrap any operations involving OpenSSL with
-- 'withOpenSSL', or they might crash:
--
-- > module Main where
-- > import OpenSSL
-- >
-- > main :: IO ()
-- > main = withOpenSSL $
-- > do ...
--
-- Since 0.10.3.5, 'withOpenSSL' is safe to be applied
-- redundantly. Library authors may wish to wrap their functions not
-- to force their users to think about initialization:
--
-- > get :: URI -> IO Response
-- > get uri = withOpenSSL $ internalImplementationOfGet uri
--
withOpenSSL :: IO a -> IO a
withOpenSSL io
-- We don't want our initialisation sequence to be interrupted
-- halfway.
= do modifyMVarMasked_ isInitialised $ \ done ->
do unless done $ do loadErrorStrings
addAllAlgorithms
libraryInit
setupMutex
return True
io
#if !MIN_VERSION_base(4,6,0)
{-|
Like 'modifyMVar_', but the @IO@ action in the second argument is executed with
asynchronous exceptions masked.
-}
{-# INLINE modifyMVarMasked_ #-}
modifyMVarMasked_ :: MVar a -> (a -> IO a) -> IO ()
modifyMVarMasked_ m io =
mask_ $ do
a <- takeMVar m
a' <- io a `onException` putMVar m a
putMVar m a'
#endif
-- This variable must be atomically fetched/stored not to initialise
-- the library twice.
isInitialised :: MVar Bool
{-# NOINLINE isInitialised #-}
isInitialised =
unsafePerformIO $ newMVar False