adding filterCmsg.

haskell · Jan 16, 2020 · d5bec3a · d5bec3a
1 parent cc498d6
commit d5bec3a
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Showing 2 changed files with 8 additions and 3 deletions.
diff --git a/Network/Socket.hs b/Network/Socket.hs
@@ -229,6 +229,7 @@ module Network.Socket
             ,CmsgIdIPv6PktInfo)
     -- ** APIs for control message
     , lookupCmsg
+    , filterCmsg
     , decodeCmsg
     , encodeCmsg
     -- ** Class and yypes for control message

diff --git a/Network/Socket/Posix/Cmsg.hsc b/Network/Socket/Posix/Cmsg.hsc
@@ -75,9 +75,13 @@ pattern CmsgIdFd = CmsgId (#const SOL_SOCKET) (#const SCM_RIGHTS)
 -- > (lookupCmsg CmsgIdIPv4TOS cmsgs >>= decodeCmsg) :: Maybe IPv4TOS
 lookupCmsg :: CmsgId -> [Cmsg] -> Maybe Cmsg
 lookupCmsg _   [] = Nothing
-lookupCmsg aid (cmsg@(Cmsg cid _):cmsgs)
-  | aid == cid = Just cmsg
-  | otherwise  = lookupCmsg aid cmsgs
+lookupCmsg cid (cmsg:cmsgs)
+  | cmsgId cmsg == cid = Just cmsg
+  | otherwise          = lookupCmsg cid cmsgs
+
+-- | Filtering control message.
+filterCmsg :: CmsgId -> [Cmsg] -> [Cmsg]
+filterCmsg cid cmsgs = filter (\cmsg -> cmsgId cmsg == cid) cmsgs
 
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