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module Network.Bind where
import Data.ByteString (ByteString)
import Network.Socket
import System.IO.Error
import Network.Address (getBindAddress)
import qualified Network.QueryResponse as QR
;import Network.QueryResponse hiding (udpTransport, udpTransport')
-- | Try (in order) a list of port numbers to bind a socket on and return a
-- 'Transport' on the first success.
--
-- Port numbers may be specified symbolically (for example, "domain" for port
-- 53) and additionally, for testing convenience, the port "fake" will pretend
-- to bind a port but instead return a null transport.
--
-- The Bool argument should be 'True' if you want a dual-socket that supports
-- both IPv4 and IPv6. Otherwise, IPv4 only will be assumed.
udpTransport' :: Show err => Bool -> [String] -> IO (Maybe (Transport err SockAddr ByteString, Socket))
udpTransport' want6 ports = do
let tryBind "fake" _ = do
dummysock <- socket (if want6 then AF_INET6 else AF_INET) Datagram defaultProtocol
return $ Just (QR.nullTransport, dummysock)
tryBind port next = do
addr <- getBindAddress port want6
(udp,sock) <- QR.udpTransport' addr
return $ Just (udp,sock)
`catchIOError` \e -> do
-- warn $ "bind-error: " <> bshow addr <> " " <> bshow e
next
foldr tryBind (return Nothing) ports
-- | Like "udpTransport\'" except that it does not return the bound 'Socket'.
udpTransport :: Show err => Bool -> [String] -> IO (Maybe (Transport err SockAddr ByteString))
udpTransport want6 ports = fmap fst <$> udpTransport' want6 ports
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