implementing socketPortSafe (haskell#319).

kazu-yamamoto · May 25, 2018 · abfddc8 · abfddc8
1 parent f48aab4
commit abfddc8
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diff --git a/Network/Socket.hs b/Network/Socket.hs
@@ -162,6 +162,7 @@ module Network.Socket
     -- ** Port number
     , PortNumber
     , defaultPort
+    , socketPortSafe
     , socketPort
 
     -- * UNIX-domain socket

diff --git a/Network/Socket/Name.hs b/Network/Socket/Name.hs
@@ -6,6 +6,7 @@ module Network.Socket.Name (
     getPeerName
   , getSocketName
   , socketPort
+  , socketPortSafe
   ) where
 
 import Foreign.Marshal.Utils (with)
@@ -48,6 +49,7 @@ foreign import CALLCONV unsafe "getsockname"
 -- was given $aNY\_PORT$.
 
 -- | Getting the port of socket.
+--   `IOError` is thrown if a port is not available.
 socketPort :: Socket            -- Connected & Bound Socket
            -> IO PortNumber     -- Port Number of Socket
 socketPort s = do
@@ -57,3 +59,14 @@ socketPort s = do
       SockAddrInet6 port _ _ _ -> return port
       _                        -> ioError $ userError "Network.Socket.socketPort: AF_UNIX not supported."
 
+-- ---------------------------------------------------------------------------
+-- socketPortSafe
+-- | Getting the port of socket.
+socketPortSafe :: Socket                -- Connected & Bound Socket
+               -> IO (Maybe PortNumber) -- Port Number of Socket
+socketPortSafe s = do
+    sa <- getSocketName s
+    return $ case sa of
+      SockAddrInet port _      -> Just port
+      SockAddrInet6 port _ _ _ -> Just port
+      _                        -> Nothing