Network.Socket

This is the main module of the network package supposed to be used with either Network.Socket.ByteString or Network.Socket.ByteString.Lazy for sending/receiving.

Here are two minimal example programs using the TCP/IP protocol: a server that echoes all data that it receives back (servicing only one client) and a client using it.

-- Echo server program
module Main (main) where

import Control.Concurrent (forkFinally)
import qualified Control.Exception as E
import Control.Monad (unless, forever, void)
import qualified Data.ByteString as S
import Network.Socket hiding (recv)
import Network.Socket.ByteString (recv, sendAll)

main :: IO ()
main = withSocketsDo $ do
    addr <- resolve "3000"
    E.bracket (open addr) close loop
  where
    resolve port = do
        let hints = defaultHints {
                addrFlags = [AI_PASSIVE]
              , addrSocketType = Stream
              }
        addr:_ <- getAddrInfo (Just hints) Nothing (Just port)
        return addr
    open addr = do
        sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
        setSocketOption sock ReuseAddr 1
        bind sock (addrAddress addr)
        -- If the prefork technique is not used,
        -- set CloseOnExec for the security reasons.
        let fd = fdSocket sock
        setCloseOnExecIfNeeded fd
        listen sock 10
        return sock
    loop sock = forever $ do
        (conn, peer) <- accept sock
        putStrLn $ "Connection from " ++ show peer
        void $ forkFinally (talk conn) (\_ -> close conn)
    talk conn = do
        msg <- recv conn 1024
        unless (S.null msg) $ do
          sendAll conn msg
          talk conn

{-# LANGUAGE OverloadedStrings #-}
-- Echo client program
module Main (main) where

import qualified Control.Exception as E
import qualified Data.ByteString.Char8 as C
import Network.Socket hiding (recv)
import Network.Socket.ByteString (recv, sendAll)

main :: IO ()
main = withSocketsDo $ do
    addr <- resolve "127.0.0.1" "3000"
    E.bracket (open addr) close talk
  where
    resolve host port = do
        let hints = defaultHints { addrSocketType = Stream }
        addr:_ <- getAddrInfo (Just hints) (Just host) (Just port)
        return addr
    open addr = do
        sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
        connect sock $ addrAddress addr
        return sock
    talk sock = do
        sendAll sock "Hello, world!"
        msg <- recv sock 1024
        putStr "Received: "
        C.putStrLn msg

The proper programming model is that one Socket is handled by a single thread. If multiple threads use one Socket concurrently, unexpected things would happen. There is one exception for multiple threads vs a single Socket: one thread reads data from a Socket only and the other thread writes data to the Socket only.

Initialisation

withSocketsDo :: IO a -> IO a

With older versions of the network library (version 2.6.0.2 or earlier) on Windows operating systems, the networking subsystem must be initialised using withSocketsDo before any networking operations can be used. eg.

main = withSocketsDo $ do {...}

It is fine to nest calls to withSocketsDo, and to perform networking operations after withSocketsDo has returned.

In newer versions of the network library (version v2.6.1.0 or later) it is only necessary to call withSocketsDo if you are calling the MkSocket constructor directly. However, for compatibility with older versions on Windows, it is good practice to always call withSocketsDo (it's very cheap).

Address information

getAddrInfo

Arguments

:: Maybe AddrInfo

preferred socket type or protocol

-> Maybe HostName

host name to look up

-> Maybe ServiceName

service name to look up

-> IO [AddrInfo]

resolved addresses, with "best" first

Resolve a host or service name to one or more addresses. The AddrInfo values that this function returns contain SockAddr values that you can pass directly to connect or bind.

This function is protocol independent. It can return both IPv4 and IPv6 address information.

The AddrInfo argument specifies the preferred query behaviour, socket options, or protocol. You can override these conveniently using Haskell's record update syntax on defaultHints, for example as follows:

>>> let hints = defaultHints { addrFlags = [AI_NUMERICHOST], addrSocketType = Stream }

You must provide a Just value for at least one of the HostName or ServiceName arguments. HostName can be either a numeric network address (dotted quad for IPv4, colon-separated hex for IPv6) or a hostname. In the latter case, its addresses will be looked up unless AI_NUMERICHOST is specified as a hint. If you do not provide a HostName value and do not set AI_PASSIVE as a hint, network addresses in the result will contain the address of the loopback interface.

If the query fails, this function throws an IO exception instead of returning an empty list. Otherwise, it returns a non-empty list of AddrInfo values.

There are several reasons why a query might result in several values. For example, the queried-for host could be multihomed, or the service might be available via several protocols.

Note: the order of arguments is slightly different to that defined for getaddrinfo in RFC 2553. The AddrInfo parameter comes first to make partial application easier.

>>> addr:_ <- getAddrInfo (Just hints) (Just "127.0.0.1") (Just "http")
>>> addrAddress addr
127.0.0.1:80

Types

type HostName = String

Either a host name e.g., "haskell.org" or a numeric host address string consisting of a dotted decimal IPv4 address or an IPv6 address e.g., "192.168.0.1".

type ServiceName = String

data AddrInfo

Constructors

AddrInfo

Fields

• addrFlags :: [AddrInfoFlag]
• addrFamily :: Family
• addrSocketType :: SocketType
• addrProtocol :: ProtocolNumber
• addrAddress :: SockAddr
• addrCanonName :: Maybe String

Instances

Eq AddrInfo

Defined in Network.Socket

Methods

(==) :: AddrInfo -> AddrInfo -> Bool

(/=) :: AddrInfo -> AddrInfo -> Bool

Show AddrInfo

Defined in Network.Socket

Methods

showsPrec :: Int -> AddrInfo -> ShowS

show :: AddrInfo -> String

showList :: [AddrInfo] -> ShowS

Storable AddrInfo

Defined in Network.Socket

Methods

sizeOf :: AddrInfo -> Int

alignment :: AddrInfo -> Int

peekElemOff :: Ptr AddrInfo -> Int -> IO AddrInfo

pokeElemOff :: Ptr AddrInfo -> Int -> AddrInfo -> IO ()

peekByteOff :: Ptr b -> Int -> IO AddrInfo

pokeByteOff :: Ptr b -> Int -> AddrInfo -> IO ()

peek :: Ptr AddrInfo -> IO AddrInfo

poke :: Ptr AddrInfo -> AddrInfo -> IO ()

defaultHints :: AddrInfo

Default hints for address lookup with getAddrInfo. The values of the addrAddress and addrCanonName fields are undefined, and are never inspected by getAddrInfo.

>>> addrFlags defaultHints
[]
>>> addrFamily defaultHints
AF_UNSPEC
>>> addrSocketType defaultHints
NoSocketType
>>> addrProtocol defaultHints
0

Flags

data AddrInfoFlag

Flags that control the querying behaviour of getAddrInfo. For more information, see https://tools.ietf.org/html/rfc3493#page-25

Constructors

AI_ADDRCONFIG

The list of returned AddrInfo values will only contain IPv4 addresses if the local system has at least one IPv4 interface configured, and likewise for IPv6. (Only some platforms support this.)

AI_ALL

If AI_ALL is specified, return all matching IPv6 and IPv4 addresses. Otherwise, this flag has no effect. (Only some platforms support this.)

AI_CANONNAME

The addrCanonName field of the first returned AddrInfo will contain the "canonical name" of the host.

AI_NUMERICHOST

The HostName argument must be a numeric address in string form, and network name lookups will not be attempted.

AI_NUMERICSERV

The ServiceName argument must be a port number in string form, and service name lookups will not be attempted. (Only some platforms support this.)

AI_PASSIVE

If no HostName value is provided, the network address in each SockAddr will be left as a "wild card". This is useful for server applications that will accept connections from any client.

AI_V4MAPPED

If an IPv6 lookup is performed, and no IPv6 addresses are found, IPv6-mapped IPv4 addresses will be returned. (Only some platforms support this.)

Instances

Eq AddrInfoFlag

Defined in Network.Socket

Methods

(==) :: AddrInfoFlag -> AddrInfoFlag -> Bool

(/=) :: AddrInfoFlag -> AddrInfoFlag -> Bool

Read AddrInfoFlag

Defined in Network.Socket

Methods

readsPrec :: Int -> ReadS AddrInfoFlag

readList :: ReadS [AddrInfoFlag]

readPrec :: ReadPrec AddrInfoFlag

readListPrec :: ReadPrec [AddrInfoFlag]

Show AddrInfoFlag

Defined in Network.Socket

Methods

showsPrec :: Int -> AddrInfoFlag -> ShowS

show :: AddrInfoFlag -> String

showList :: [AddrInfoFlag] -> ShowS

addrInfoFlagImplemented :: AddrInfoFlag -> Bool

Indicate whether the given AddrInfoFlag will have any effect on this system.

Socket operations

connect :: Socket -> SockAddr -> IO ()

Connect to a remote socket at address.

bind :: Socket -> SockAddr -> IO ()

Bind the socket to an address. The socket must not already be bound. The Family passed to bind must be the same as that passed to socket. If the special port number defaultPort is passed then the system assigns the next available use port.

listen :: Socket -> Int -> IO ()

Listen for connections made to the socket. The second argument specifies the maximum number of queued connections and should be at least 1; the maximum value is system-dependent (usually 5).

accept :: Socket -> IO (Socket, SockAddr)

Accept a connection. The socket must be bound to an address and listening for connections. The return value is a pair (conn, address) where conn is a new socket object usable to send and receive data on the connection, and address is the address bound to the socket on the other end of the connection.

Closing

close :: Socket -> IO ()

Close the socket. This function does not throw exceptions even if the underlying system call returns errors.

Sending data to or receiving data from closed socket may lead to undefined behaviour.

If multiple threads use the same socket and one uses fdSocket and the other use close, unexpected behavior may happen. For more information, please refer to the documentation of fdSocket.

close' :: Socket -> IO ()

Close the socket. This function throws exceptions if the underlying system call returns errors.

Sending data to or receiving data from closed socket may lead to undefined behaviour.

shutdown :: Socket -> ShutdownCmd -> IO ()

Shut down one or both halves of the connection, depending on the second argument to the function. If the second argument is ShutdownReceive, further receives are disallowed. If it is ShutdownSend, further sends are disallowed. If it is ShutdownBoth, further sends and receives are disallowed.

data ShutdownCmd

Constructors

ShutdownReceive

ShutdownSend

ShutdownBoth

Socket options

data SocketOption

Socket options for use with setSocketOption and getSocketOption.

The existence of a constructor does not imply that the relevant option is supported on your system: see isSupportedSocketOption

Constructors

Debug

SO_DEBUG

ReuseAddr

SO_REUSEADDR

Type

SO_TYPE

SoError

SO_ERROR

DontRoute

SO_DONTROUTE

Broadcast

SO_BROADCAST

SendBuffer

SO_SNDBUF

RecvBuffer

SO_RCVBUF

KeepAlive

SO_KEEPALIVE

OOBInline

SO_OOBINLINE

TimeToLive

IP_TTL

MaxSegment

TCP_MAXSEG

NoDelay

TCP_NODELAY

Cork

TCP_CORK

Linger

SO_LINGER

ReusePort

SO_REUSEPORT

RecvLowWater

SO_RCVLOWAT

SendLowWater

SO_SNDLOWAT

RecvTimeOut

SO_RCVTIMEO

SendTimeOut

SO_SNDTIMEO

UseLoopBack

SO_USELOOPBACK

UserTimeout

TCP_USER_TIMEOUT

IPv6Only

IPV6_V6ONLY

CustomSockOpt (CInt, CInt)

Instances

Show SocketOption

Defined in Network.Socket

Methods

showsPrec :: Int -> SocketOption -> ShowS

show :: SocketOption -> String

showList :: [SocketOption] -> ShowS

isSupportedSocketOption :: SocketOption -> Bool

Does the SocketOption exist on this system?

getSocketOption :: Socket -> SocketOption -> IO Int

Get a socket option that gives an Int value. There is currently no API to get e.g. the timeval socket options

setSocketOption :: Socket -> SocketOption -> Int -> IO ()

Set a socket option that expects an Int value. There is currently no API to set e.g. the timeval socket options

Socket

data Socket

A socket data type. Sockets are not GCed unless they are closed by close.

Constructors

MkSocket CInt Family SocketType ProtocolNumber (MVar SocketStatus)

Deprecated: MkSocket will not be available in version 3.0.0.0 or later. Use fdSocket instead

Instances

Eq Socket

Defined in Network.Socket.Types

Methods

(==) :: Socket -> Socket -> Bool

(/=) :: Socket -> Socket -> Bool

Show Socket

Defined in Network.Socket.Types

Methods

showsPrec :: Int -> Socket -> ShowS

show :: Socket -> String

showList :: [Socket] -> ShowS

socket :: Family -> SocketType -> ProtocolNumber -> IO Socket

Create a new socket using the given address family, socket type and protocol number. The address family is usually AF_INET, AF_INET6, or AF_UNIX. The socket type is usually Stream or Datagram. The protocol number is usually defaultProtocol. If AF_INET6 is used and the socket type is Stream or Datagram, the IPv6Only socket option is set to 0 so that both IPv4 and IPv6 can be handled with one socket.

>>> let hints = defaultHints { addrFlags = [AI_NUMERICHOST, AI_NUMERICSERV], addrSocketType = Stream }
>>> addr:_ <- getAddrInfo (Just hints) (Just "127.0.0.1") (Just "5000")
>>> sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
>>> bind sock (addrAddress addr)
>>> getSocketName sock
127.0.0.1:5000

fdSocket :: Socket -> CInt

Obtaining the file descriptor from a socket.

If a Socket is shared with multiple threads and one uses fdSocket, unexpected issues may happen. Consider the following scenario:

1) Thread A acquires a Fd from Socket by fdSocket.

2) Thread B close the Socket.

3) Thread C opens a new Socket. Unfortunately it gets the same Fd number which thread A is holding.

In this case, it is safer for Thread A to clone Fd by dup. But this would still suffer from a rase condition between fdSocket and close.

mkSocket :: CInt -> Family -> SocketType -> ProtocolNumber -> SocketStatus -> IO Socket

Smart constructor for constructing a Socket. It should only be called once for every new file descriptor. The caller must make sure that the socket is in non-blocking mode. See setNonBlockIfNeeded.

socketToHandle :: Socket -> IOMode -> IO Handle

Turns a Socket into an Handle. By default, the new handle is unbuffered. Use hSetBuffering to change the buffering.

Note that since a Handle is automatically closed by a finalizer when it is no longer referenced, you should avoid doing any more operations on the Socket after calling socketToHandle. To close the Socket after socketToHandle, call hClose on the Handle.

Types of Socket

data SocketType

Socket Types.

The existence of a constructor does not necessarily imply that that socket type is supported on your system: see isSupportedSocketType.

Constructors

NoSocketType

0, used in getAddrInfo hints, for example

Stream

SOCK_STREAM

Datagram

SOCK_DGRAM

Raw

SOCK_RAW

RDM

SOCK_RDM

SeqPacket

SOCK_SEQPACKET

Instances

Eq SocketType

Defined in Network.Socket.Types

Methods

(==) :: SocketType -> SocketType -> Bool

(/=) :: SocketType -> SocketType -> Bool

Ord SocketType

Defined in Network.Socket.Types

Methods

compare :: SocketType -> SocketType -> Ordering

(<) :: SocketType -> SocketType -> Bool

(<=) :: SocketType -> SocketType -> Bool

(>) :: SocketType -> SocketType -> Bool

(>=) :: SocketType -> SocketType -> Bool

max :: SocketType -> SocketType -> SocketType

min :: SocketType -> SocketType -> SocketType

Read SocketType

Defined in Network.Socket.Types

Methods

readsPrec :: Int -> ReadS SocketType

readList :: ReadS [SocketType]

readPrec :: ReadPrec SocketType

readListPrec :: ReadPrec [SocketType]

Show SocketType

Defined in Network.Socket.Types

Methods

showsPrec :: Int -> SocketType -> ShowS

show :: SocketType -> String

showList :: [SocketType] -> ShowS

isSupportedSocketType :: SocketType -> Bool

Does the SOCK_ constant corresponding to the given SocketType exist on this system?

Family

data Family

Address families.

A constructor being present here does not mean it is supported by the operating system: see isSupportedFamily.

Constructors

AF_UNSPEC

AF_UNIX

AF_INET

AF_INET6

AF_IMPLINK

AF_PUP

AF_CHAOS

AF_NS

AF_NBS

AF_ECMA

AF_DATAKIT

AF_CCITT

AF_SNA

AF_DECnet

AF_DLI

AF_LAT

AF_HYLINK

AF_APPLETALK

AF_ROUTE

AF_NETBIOS

AF_NIT

AF_802

AF_ISO

AF_OSI

AF_NETMAN

AF_X25

AF_AX25

AF_OSINET

AF_GOSSIP

AF_IPX

Pseudo_AF_XTP

AF_CTF

AF_WAN

AF_SDL

AF_NETWARE

AF_NDD

AF_INTF

AF_COIP

AF_CNT

Pseudo_AF_RTIP

Pseudo_AF_PIP

AF_SIP

AF_ISDN

Pseudo_AF_KEY

AF_NATM

AF_ARP

Pseudo_AF_HDRCMPLT

AF_ENCAP

AF_LINK

AF_RAW

AF_RIF

AF_NETROM

AF_BRIDGE

AF_ATMPVC

AF_ROSE

AF_NETBEUI

AF_SECURITY

AF_PACKET

AF_ASH

AF_ECONET

AF_ATMSVC

AF_IRDA

AF_PPPOX

AF_WANPIPE

AF_BLUETOOTH

AF_CAN

Instances

Eq Family

Defined in Network.Socket.Types

Methods

(==) :: Family -> Family -> Bool

(/=) :: Family -> Family -> Bool

Ord Family

Defined in Network.Socket.Types

Methods

compare :: Family -> Family -> Ordering

(<) :: Family -> Family -> Bool

(<=) :: Family -> Family -> Bool

(>) :: Family -> Family -> Bool

(>=) :: Family -> Family -> Bool

max :: Family -> Family -> Family

min :: Family -> Family -> Family

Read Family

Defined in Network.Socket.Types

Methods

readsPrec :: Int -> ReadS Family

readList :: ReadS [Family]

readPrec :: ReadPrec Family

readListPrec :: ReadPrec [Family]

Show Family

Defined in Network.Socket.Types

Methods

showsPrec :: Int -> Family -> ShowS

show :: Family -> String

showList :: [Family] -> ShowS

isSupportedFamily :: Family -> Bool

Does the AF_ constant corresponding to the given family exist on this system?

Protocol number

type ProtocolNumber = CInt

defaultProtocol :: ProtocolNumber

This is the default protocol for a given service.

Socket address

data SockAddr

The existence of a constructor does not necessarily imply that that socket address type is supported on your system: see isSupportedSockAddr.

Constructors

SockAddrInet PortNumber HostAddress

SockAddrInet6 PortNumber FlowInfo HostAddress6 ScopeID

SockAddrUnix String

SockAddrCan Int32

Deprecated: This will be removed in 3.0

Instances

Eq SockAddr

Defined in Network.Socket.Types

Methods

(==) :: SockAddr -> SockAddr -> Bool

(/=) :: SockAddr -> SockAddr -> Bool

Ord SockAddr

Defined in Network.Socket.Types

Methods

compare :: SockAddr -> SockAddr -> Ordering

(<) :: SockAddr -> SockAddr -> Bool

(<=) :: SockAddr -> SockAddr -> Bool

(>) :: SockAddr -> SockAddr -> Bool

(>=) :: SockAddr -> SockAddr -> Bool

max :: SockAddr -> SockAddr -> SockAddr

min :: SockAddr -> SockAddr -> SockAddr

Show SockAddr

Defined in Network.Socket

Methods

showsPrec :: Int -> SockAddr -> ShowS

show :: SockAddr -> String

showList :: [SockAddr] -> ShowS

isSupportedSockAddr :: SockAddr -> Bool

Is the socket address type supported on this system?

getPeerName :: Socket -> IO SockAddr

getSocketName :: Socket -> IO SockAddr

Host address

type HostAddress = Word32

The raw network byte order number is read using host byte order. Therefore on little-endian architectures the byte order is swapped. For example 127.0.0.1 is represented as 0x0100007f on little-endian hosts and as 0x7f000001 on big-endian hosts.

For direct manipulation prefer hostAddressToTuple and tupleToHostAddress.

hostAddressToTuple :: HostAddress -> (Word8, Word8, Word8, Word8)

Converts HostAddress to representation-independent IPv4 quadruple. For example for 127.0.0.1 the function will return (0x7f, 0, 0, 1) regardless of host endianness.

tupleToHostAddress :: (Word8, Word8, Word8, Word8) -> HostAddress

Converts IPv4 quadruple to HostAddress.

Host address6

type HostAddress6 = (Word32, Word32, Word32, Word32)

Independent of endianness. For example ::1 is stored as (0, 0, 0, 1).

For direct manipulation prefer hostAddress6ToTuple and tupleToHostAddress6.

hostAddress6ToTuple :: HostAddress6 -> (Word16, Word16, Word16, Word16, Word16, Word16, Word16, Word16)

tupleToHostAddress6 :: (Word16, Word16, Word16, Word16, Word16, Word16, Word16, Word16) -> HostAddress6

Flow Info

type FlowInfo = Word32

Scope ID

type ScopeID = Word32

ifNameToIndex :: String -> IO (Maybe Int)

Returns the index corresponding to the interface name.

Since 2.7.0.0.

ifIndexToName :: Int -> IO (Maybe String)

Returns the interface name corresponding to the index.

Since 2.7.0.0.

Port number

data PortNumber

Use the Num instance (i.e. use a literal) to create a PortNumber value.

>>> 1 :: PortNumber
1
>>> read "1" :: PortNumber
1
>>> show (12345 :: PortNumber)
"12345"
>>> 50000 < (51000 :: PortNumber)
True
>>> 50000 < (52000 :: PortNumber)
True
>>> 50000 + (10000 :: PortNumber)
60000

Instances

Enum PortNumber

Defined in Network.Socket.Types

Methods

succ :: PortNumber -> PortNumber

pred :: PortNumber -> PortNumber

toEnum :: Int -> PortNumber

fromEnum :: PortNumber -> Int

enumFrom :: PortNumber -> [PortNumber]

enumFromThen :: PortNumber -> PortNumber -> [PortNumber]

enumFromTo :: PortNumber -> PortNumber -> [PortNumber]

enumFromThenTo :: PortNumber -> PortNumber -> PortNumber -> [PortNumber]

Eq PortNumber

Defined in Network.Socket.Types

Methods

(==) :: PortNumber -> PortNumber -> Bool

(/=) :: PortNumber -> PortNumber -> Bool

Integral PortNumber

Defined in Network.Socket.Types

Methods

quot :: PortNumber -> PortNumber -> PortNumber

rem :: PortNumber -> PortNumber -> PortNumber

div :: PortNumber -> PortNumber -> PortNumber

mod :: PortNumber -> PortNumber -> PortNumber

quotRem :: PortNumber -> PortNumber -> (PortNumber, PortNumber)

divMod :: PortNumber -> PortNumber -> (PortNumber, PortNumber)

toInteger :: PortNumber -> Integer

Num PortNumber

Defined in Network.Socket.Types

Methods

(+) :: PortNumber -> PortNumber -> PortNumber

(-) :: PortNumber -> PortNumber -> PortNumber

(*) :: PortNumber -> PortNumber -> PortNumber

negate :: PortNumber -> PortNumber

abs :: PortNumber -> PortNumber

signum :: PortNumber -> PortNumber

fromInteger :: Integer -> PortNumber

Ord PortNumber

Defined in Network.Socket.Types

Methods

compare :: PortNumber -> PortNumber -> Ordering

(<) :: PortNumber -> PortNumber -> Bool

(<=) :: PortNumber -> PortNumber -> Bool

(>) :: PortNumber -> PortNumber -> Bool

(>=) :: PortNumber -> PortNumber -> Bool

max :: PortNumber -> PortNumber -> PortNumber

min :: PortNumber -> PortNumber -> PortNumber

Read PortNumber

Defined in Network.Socket.Types

Methods

readsPrec :: Int -> ReadS PortNumber

readList :: ReadS [PortNumber]

readPrec :: ReadPrec PortNumber

readListPrec :: ReadPrec [PortNumber]

Real PortNumber

Defined in Network.Socket.Types

Methods

toRational :: PortNumber -> Rational

Show PortNumber

Defined in Network.Socket.Types

Methods

showsPrec :: Int -> PortNumber -> ShowS

show :: PortNumber -> String

showList :: [PortNumber] -> ShowS

Storable PortNumber

Defined in Network.Socket.Types

Methods

sizeOf :: PortNumber -> Int

alignment :: PortNumber -> Int

peekElemOff :: Ptr PortNumber -> Int -> IO PortNumber

pokeElemOff :: Ptr PortNumber -> Int -> PortNumber -> IO ()

peekByteOff :: Ptr b -> Int -> IO PortNumber

pokeByteOff :: Ptr b -> Int -> PortNumber -> IO ()

peek :: Ptr PortNumber -> IO PortNumber

poke :: Ptr PortNumber -> PortNumber -> IO ()

defaultPort :: PortNumber

socketPortSafe :: Socket -> IO (Maybe PortNumber)

Getting the port of socket.

socketPort :: Socket -> IO PortNumber

Getting the port of socket. IOError is thrown if a port is not available.

UNIX-domain socket

isUnixDomainSocketAvailable :: Bool

Whether or not UNIX-domain sockets are available.

Since 3.0.0.0.

socketPair :: Family -> SocketType -> ProtocolNumber -> IO (Socket, Socket)

Build a pair of connected socket objects using the given address family, socket type, and protocol number. Address family, socket type, and protocol number are as for the socket function above. Availability: Unix.

sendFd :: Socket -> CInt -> IO ()

recvFd :: Socket -> IO CInt

Receive a file descriptor over a 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.

getPeerCredential :: Socket -> IO (Maybe CUInt, Maybe CUInt, Maybe CUInt)

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.

Name information

data NameInfoFlag

Flags that control the querying behaviour of getNameInfo. For more information, see https://tools.ietf.org/html/rfc3493#page-30

Constructors

NI_DGRAM

Resolve a datagram-based service name. This is required only for the few protocols that have different port numbers for their datagram-based versions than for their stream-based versions.

NI_NAMEREQD

If the hostname cannot be looked up, an IO error is thrown.

NI_NOFQDN

If a host is local, return only the hostname part of the FQDN.

NI_NUMERICHOST

The name of the host is not looked up. Instead, a numeric representation of the host's address is returned. For an IPv4 address, this will be a dotted-quad string. For IPv6, it will be colon-separated hexadecimal.

NI_NUMERICSERV

The name of the service is not looked up. Instead, a numeric representation of the service is returned.

Instances

Eq NameInfoFlag

Defined in Network.Socket

Methods

(==) :: NameInfoFlag -> NameInfoFlag -> Bool

(/=) :: NameInfoFlag -> NameInfoFlag -> Bool

Read NameInfoFlag

Defined in Network.Socket

Methods

readsPrec :: Int -> ReadS NameInfoFlag

readList :: ReadS [NameInfoFlag]

readPrec :: ReadPrec NameInfoFlag

readListPrec :: ReadPrec [NameInfoFlag]

Show NameInfoFlag

Defined in Network.Socket

Methods

showsPrec :: Int -> NameInfoFlag -> ShowS

show :: NameInfoFlag -> String

showList :: [NameInfoFlag] -> ShowS

getNameInfo

Arguments

:: [NameInfoFlag]

flags to control lookup behaviour

-> Bool

whether to look up a hostname

-> Bool

whether to look up a service name

-> SockAddr

the address to look up

-> IO (Maybe HostName, Maybe ServiceName)

Resolve an address to a host or service name. This function is protocol independent. The list of NameInfoFlag values controls query behaviour.

If a host or service's name cannot be looked up, then the numeric form of the address or service will be returned.

If the query fails, this function throws an IO exception.

Example: (hostName, _) <- getNameInfo [] True False myAddress

Low level operations

setCloseOnExecIfNeeded :: CInt -> IO ()

Set the close_on_exec flag on Unix. On Windows, nothing is done.

Since 2.7.0.0.

getCloseOnExec :: CInt -> IO Bool

Get the nonblocking flag. On Windows, this function always returns False.

Since 2.7.0.0.

setNonBlockIfNeeded :: CInt -> IO ()

Set the nonblocking flag on Unix. On Windows, nothing is done.

getNonBlock :: CInt -> IO Bool

Get the close_on_exec flag. On Windows, this function always returns False.

Since 2.7.0.0.

Sending and receiving data

sendBuf :: Socket -> Ptr Word8 -> Int -> IO Int

Send data to the socket. The socket must be connected to a remote socket. Returns the number of bytes sent. Applications are responsible for ensuring that all data has been sent.

Sending data to closed socket may lead to undefined behaviour.

recvBuf :: Socket -> Ptr Word8 -> Int -> IO Int

Receive data from the socket. The socket must be in a connected state. This function may return fewer bytes than specified. If the message is longer than the specified length, it may be discarded depending on the type of socket. This function may block until a message arrives.

Considering hardware and network realities, the maximum number of bytes to receive should be a small power of 2, e.g., 4096.

For TCP sockets, a zero length return value means the peer has closed its half side of the connection.

Receiving data from closed socket may lead to undefined behaviour.

sendBufTo :: Socket -> Ptr a -> Int -> SockAddr -> IO Int

Send data to the socket. The recipient can be specified explicitly, so the socket need not be in a connected state. Returns the number of bytes sent. Applications are responsible for ensuring that all data has been sent.

recvBufFrom :: Socket -> Ptr a -> Int -> IO (Int, SockAddr)

Receive data from the socket, writing it into buffer instead of creating a new string. The socket need not be in a connected state. Returns (nbytes, address) where nbytes is the number of bytes received and address is a SockAddr representing the address of the sending socket.

NOTE: blocking on Windows unless you compile with -threaded (see GHC ticket #1129)

Special constants

maxListenQueue :: Int

This is the value of SOMAXCONN, typically 128. 128 is good enough for normal network servers but is too small for high performance servers.

Deprecated

Deprecated sending and receiving

send :: Socket -> String -> IO Int

Deprecated: Use send defined in Network.Socket.ByteString

Send data to the socket. The socket must be connected to a remote socket. Returns the number of bytes sent. Applications are responsible for ensuring that all data has been sent.

Sending data to closed socket may lead to undefined behaviour.

sendTo :: Socket -> String -> SockAddr -> IO Int

Deprecated: Use sendTo defined in Network.Socket.ByteString

Send data to the socket. The recipient can be specified explicitly, so the socket need not be in a connected state. Returns the number of bytes sent. Applications are responsible for ensuring that all data has been sent.

NOTE: blocking on Windows unless you compile with -threaded (see GHC ticket #1129)

recv :: Socket -> Int -> IO String

Deprecated: Use recv defined in Network.Socket.ByteString

Receive data from the socket. The socket must be in a connected state. This function may return fewer bytes than specified. If the message is longer than the specified length, it may be discarded depending on the type of socket. This function may block until a message arrives.

Considering hardware and network realities, the maximum number of bytes to receive should be a small power of 2, e.g., 4096.

For TCP sockets, a zero length return value means the peer has closed its half side of the connection.

Receiving data from closed socket may lead to undefined behaviour.

recvFrom :: Socket -> Int -> IO (String, Int, SockAddr)

Deprecated: Use recvFrom defined in Network.Socket.ByteString

Receive data from the socket. The socket need not be in a connected state. Returns (bytes, nbytes, address) where bytes is a String of length nbytes representing the data received and address is a SockAddr representing the address of the sending socket.

NOTE: blocking on Windows unless you compile with -threaded (see GHC ticket #1129)

recvLen :: Socket -> Int -> IO (String, Int)

Deprecated: Use recv defined in Network.Socket.ByteString with "Data.Bytestring.length"

Deprecated address functions

htonl :: Word32 -> Word32

Deprecated: Use getAddrInfo instead

Converts the from host byte order to network byte order.

ntohl :: Word32 -> Word32

Deprecated: Use getAddrInfo instead

Converts the from network byte order to host byte order.

inet_addr :: String -> IO HostAddress

Deprecated: Use "getAddrInfo" instead

inet_ntoa :: HostAddress -> IO String

Deprecated: Use "getNameInfo" instead

Deprecated socket operations

bindSocket :: Socket -> SockAddr -> IO ()

Deprecated: use bind

Deprecated alias for bind.

sClose :: Socket -> IO ()

Deprecated: use close

Deprecated alias for close.

Deprecated socket status

data SocketStatus

Deprecated: SocketStatus will be removed

The status of the socket as determined by this library, not necessarily reflecting the state of the connection itself.

For example, the Closed status is applied when the close function is called.

Constructors

NotConnected

Newly created, unconnected socket

Bound

Bound, via bind

Listening

Listening, via listen

Connected

Connected or accepted, via connect or accept

ConvertedToHandle

Is now a Handle (via socketToHandle), don't touch

Closed

Closed was closed by close

Instances

Eq SocketStatus

Defined in Network.Socket.Types

Methods

(==) :: SocketStatus -> SocketStatus -> Bool

(/=) :: SocketStatus -> SocketStatus -> Bool

Show SocketStatus

Defined in Network.Socket.Types

Methods

showsPrec :: Int -> SocketStatus -> ShowS

show :: SocketStatus -> String

showList :: [SocketStatus] -> ShowS

isConnected :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

Determines whether close has been used on the Socket. This does not indicate any status about the socket beyond this. If the socket has been closed remotely, this function can still return True.

isBound :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

isListening :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

isReadable :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

isWritable :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

sIsConnected :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

sIsBound :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

sIsListening :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

sIsReadable :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

sIsWritable :: Socket -> IO Bool

Deprecated: SocketStatus will be removed

Deprecated special constants

aNY_PORT :: PortNumber

Deprecated: Use defaultPort instead

iNADDR_ANY :: HostAddress

Deprecated: Use getAddrInfo instead

The IPv4 wild card address.

iN6ADDR_ANY :: HostAddress6

Deprecated: Use getAddrInfo instead

The IPv6 wild card address.

sOMAXCONN :: Int

Deprecated: Use maxListenQueue instead

sOL_SOCKET :: Int

Deprecated: This is not necessary anymore

sCM_RIGHTS :: Int

Deprecated: This is not necessary anymore

Decrecated internal functions

packFamily :: Family -> CInt

unpackFamily :: CInt -> Family

packSocketType :: SocketType -> CInt

Deprecated: packSocketType will not be available in version 3.0.0.0 or later.

Decrecated UNIX-domain functions

getPeerCred :: Socket -> IO (CUInt, CUInt, CUInt)

Deprecated: Use getPeerCredential instead

Returns the processID, userID and groupID of the socket's peer.

Only available on platforms that support SO_PEERCRED or GETPEEREID(3) on domain sockets. GETPEEREID(3) returns userID and groupID. processID is always 0.

Orphan instances

Show SockAddr

Methods

showsPrec :: Int -> SockAddr -> ShowS

show :: SockAddr -> String

showList :: [SockAddr] -> ShowS