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
• 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
import Network.Socket.ByteString (recv, sendAll)

main :: IO ()
main = runTCPServer Nothing "3000" talk
  where
    talk s = do
        msg <- recv s 1024
        unless (S.null msg) $ do
          sendAll s msg
          talk s

-- from the "network-run" package.
runTCPServer :: Maybe HostName -> ServiceName -> (Socket -> IO a) -> IO a
runTCPServer mhost port server = withSocketsDo $ do
    addr <- resolve
    E.bracket (open addr) close loop
  where
    resolve = do
        let hints = defaultHints {
                addrFlags = [AI_PASSIVE]
              , addrSocketType = Stream
              }
        head <$> getAddrInfo (Just hints) mhost (Just port)
    open addr = do
        sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
        setSocketOption sock ReuseAddr 1
        withFdSocket sock $ setCloseOnExecIfNeeded
        bind sock $ addrAddress addr
        listen sock 1024
        return sock
    loop sock = forever $ do
        (conn, _peer) <- accept sock
        void $ forkFinally (server conn) (const $ gracefulClose conn 5000)

{-# 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
import Network.Socket.ByteString (recv, sendAll)

main :: IO ()
main = runTCPClient "127.0.0.1" "3000" $ \s -> do
    sendAll s "Hello, world!"
    msg <- recv s 1024
    putStr "Received: "
    C.putStrLn msg

-- from the "network-run" package.
runTCPClient :: HostName -> ServiceName -> (Socket -> IO a) -> IO a
runTCPClient host port client = withSocketsDo $ do
    addr <- resolve
    E.bracket (open addr) close client
  where
    resolve = do
        let hints = defaultHints { addrSocketType = Stream }
        head <$> getAddrInfo (Just hints) (Just host) (Just port)
    open addr = do
        sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
        connect sock $ addrAddress addr
        return sock

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.

withSocketsDo is not necessary for the current network library. 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

Either a service name e.g., "http" or a numeric port number.

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.Info

Methods

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

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

Show AddrInfo

Defined in Network.Socket.Info

Methods

showsPrec :: Int -> AddrInfo -> ShowS

show :: AddrInfo -> String

showList :: [AddrInfo] -> ShowS

Storable AddrInfo

Defined in Network.Socket.Info

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.Info

Methods

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

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

Read AddrInfoFlag

Defined in Network.Socket.Info

Methods

readsPrec :: Int -> ReadS AddrInfoFlag

readList :: ReadS [AddrInfoFlag]

readPrec :: ReadPrec AddrInfoFlag

readListPrec :: ReadPrec [AddrInfoFlag]

Show AddrInfoFlag

Defined in Network.Socket.Info

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. On Unix, FD_CLOEXEC is set to the new Socket.

Closing

close :: Socket -> IO ()

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

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

close' :: Socket -> IO ()

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

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

Closing a socket gracefully. This sends TCP FIN and check if TCP FIN is received from the peer. The second argument is time out to receive TCP FIN in millisecond. In both normal cases and error cases, socket is deallocated finally.

Since: 3.1.1.0

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: timeout in seconds, 0 means disabling/disabled.

ReusePort

SO_REUSEPORT

RecvLowWater

SO_RCVLOWAT

SendLowWater

SO_SNDLOWAT

RecvTimeOut

SO_RCVTIMEO: this does not work at this moment.

SendTimeOut

SO_SNDTIMEO: this does not work at this moment.

UseLoopBack

SO_USELOOPBACK

UserTimeout

TCP_USER_TIMEOUT

IPv6Only

IPV6_V6ONLY: don't use this on OpenBSD.

CustomSockOpt (CInt, CInt)

Instances

Show SocketOption

Defined in Network.Socket.Options

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

Basic type for a socket.

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.

>>> import Network.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)
>>> Network.Socket.bind sock (addrAddress addr)
>>> getSocketName sock
127.0.0.1:5000

withFdSocket :: Socket -> (CInt -> IO r) -> IO r

Get a file descriptor from a Socket. The socket will never be closed automatically before withFdSocket completes, but it may still be closed by an explicit call to close or close', either before or during the call.

The file descriptor must not be used after withFdSocket returns, because the Socket may have been garbage-collected, invalidating the file descriptor.

Since: 3.1.0.0

unsafeFdSocket :: Socket -> IO CInt

Getting a file descriptor from a socket.

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

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

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 race condition between unsafeFdSocket and close.

If you use this function, you need to guarantee that the Socket does not get garbage-collected until after you finish using the file descriptor. touchSocket can be used for this purpose.

A safer option is to use withFdSocket instead.

touchSocket :: Socket -> IO ()

Ensure that the given Socket stays alive (i.e. not garbage-collected) at the given place in the sequence of IO actions. This function can be used in conjunction with unsafeFdSocket to guarantee that the file descriptor is not prematurely freed.

fd <- unsafeFdSocket sock
-- using fd with blocking operations such as accept(2)
touchSocket sock

socketToFd :: Socket -> IO CInt

Socket is closed and a duplicated file descriptor is returned. The duplicated descriptor is no longer subject to the possibility of unexpectedly being closed if the socket is finalized. It is now the caller's responsibility to ultimately close the duplicated file descriptor.

fdSocket :: Socket -> IO CInt

Deprecated: Use withFdSocket or unsafeFdSocket instead

Currently, this is an alias of unsafeFdSocket.

mkSocket :: CInt -> IO Socket

Creating a socket from a file descriptor.

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?

getSocketType :: Socket -> IO SocketType

Get the SocketType of an active socket.

Since: 3.0.1.0

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

unspecified

AF_UNIX

UNIX-domain

AF_INET

Internet Protocol version 4

AF_INET6

Internet Protocol version 6

AF_IMPLINK

Arpanet imp addresses

AF_PUP

pup protocols: e.g. BSP

AF_CHAOS

mit CHAOS protocols

AF_NS

XEROX NS protocols

AF_NBS

nbs protocols

AF_ECMA

european computer manufacturers

AF_DATAKIT

datakit protocols

AF_CCITT

CCITT protocols, X.25 etc

AF_SNA

IBM SNA

AF_DECnet

DECnet

AF_DLI

Direct data link interface

AF_LAT

LAT

AF_HYLINK

NSC Hyperchannel

AF_APPLETALK

Apple Talk

AF_ROUTE

Internal Routing Protocol (aka AF_NETLINK)

AF_NETBIOS

NetBios-style addresses

AF_NIT

Network Interface Tap

AF_802

IEEE 802.2, also ISO 8802

AF_ISO

ISO protocols

AF_OSI

umbrella of all families used by OSI

AF_NETMAN

DNA Network Management

AF_X25

CCITT X.25

AF_AX25

AX25

AF_OSINET

AFI

AF_GOSSIP

US Government OSI

AF_IPX

Novell Internet Protocol

Pseudo_AF_XTP

eXpress Transfer Protocol (no AF)

AF_CTF

Common Trace Facility

AF_WAN

Wide Area Network protocols

AF_SDL

SGI Data Link for DLPI

AF_NETWARE

Netware

AF_NDD

NDD

AF_INTF

Debugging use only

AF_COIP

connection-oriented IP, aka ST II

AF_CNT

Computer Network Technology

Pseudo_AF_RTIP

Help Identify RTIP packets

Pseudo_AF_PIP

Help Identify PIP packets

AF_SIP

Simple Internet Protocol

AF_ISDN

Integrated Services Digital Network

Pseudo_AF_KEY

Internal key-management function

AF_NATM

native ATM access

AF_ARP

ARP (RFC 826)

Pseudo_AF_HDRCMPLT

Used by BPF to not rewrite hdrs in iface output

AF_ENCAP

ENCAP

AF_LINK

Link layer interface

AF_RAW

Link layer interface

AF_RIF

raw interface

AF_NETROM

Amateur radio NetROM

AF_BRIDGE

multiprotocol bridge

AF_ATMPVC

ATM PVCs

AF_ROSE

Amateur Radio X.25 PLP

AF_NETBEUI

Netbeui 802.2LLC

AF_SECURITY

Security callback pseudo AF

AF_PACKET

Packet family

AF_ASH

Ash

AF_ECONET

Acorn Econet

AF_ATMSVC

ATM SVCs

AF_IRDA

IRDA sockets

AF_PPPOX

PPPoX sockets

AF_WANPIPE

Wanpipe API sockets

AF_BLUETOOTH

bluetooth sockets

AF_CAN

Controller Area Network

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?

packFamily :: Family -> CInt

Converting Family to CInt.

unpackFamily :: CInt -> Family

Converting CInt to Family.

Protocol number

type ProtocolNumber = CInt

Protocol number.

defaultProtocol :: ProtocolNumber

This is the default protocol for a given service.

>>> defaultProtocol
0

Basic socket address type

data SockAddr

Socket addresses. 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

The path must have fewer than 104 characters. All of these characters must have code points less than 256.

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.Info

Methods

showsPrec :: Int -> SockAddr -> ShowS

show :: SockAddr -> String

showList :: [SockAddr] -> ShowS

NFData SockAddr

Defined in Network.Socket.Types

Methods

rnf :: SockAddr -> ()

SocketAddress SockAddr

Defined in Network.Socket.Types

Methods

sizeOfSocketAddress :: SockAddr -> Int

peekSocketAddress :: Ptr SockAddr -> IO SockAddr

pokeSocketAddress :: Ptr a -> SockAddr -> IO ()

isSupportedSockAddr :: SockAddr -> Bool

Is the socket address type supported on this system?

getPeerName :: Socket -> IO SockAddr

Getting peer's SockAddr.

getSocketName :: Socket -> IO SockAddr

Getting my 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)

Converts HostAddress6 to representation-independent IPv6 octuple.

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

Converts IPv6 octuple to HostAddress6.

Flow Info

type FlowInfo = Word32

Flow information.

Scope ID

type ScopeID = Word32

Scope identifier.

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

Port number. 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

Default port number.

>>> defaultPort
0

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 2.7.0.0.

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

Build a pair of connected socket objects. For portability, use this function in the case where isUnixDomainSocketAvailable is True and specify AF_UNIX to the first argument.

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

Send a file descriptor over a UNIX-domain socket. Use this function in the case where isUnixDomainSocketAvailable is True.

recvFd :: Socket -> IO CInt

Receive a file descriptor over a UNIX-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. Use this function in the case where isUnixDomainSocketAvailable is True.

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

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.

>>> addr:_ <- getAddrInfo (Just defaultHints) (Just "127.0.0.1") (Just "http")
>>> getNameInfo [NI_NUMERICHOST, NI_NUMERICSERV] True True $ addrAddress addr
(Just "127.0.0.1",Just "80")

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.Info

Methods

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

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

Read NameInfoFlag

Defined in Network.Socket.Info

Methods

readsPrec :: Int -> ReadS NameInfoFlag

readList :: ReadS [NameInfoFlag]

readPrec :: ReadPrec NameInfoFlag

readListPrec :: ReadPrec [NameInfoFlag]

Show NameInfoFlag

Defined in Network.Socket.Info

Methods

showsPrec :: Int -> NameInfoFlag -> ShowS

show :: NameInfoFlag -> String

showList :: [NameInfoFlag] -> ShowS

Low level

socket 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 close_on_exec 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 nonblocking 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.

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.

The return value is the length of received data. Zero means EOF. Historical note: Version 2.8.x.y or earlier, an EOF error was thrown. This was changed in version 3.0.

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.

If the first return value is zero, it means EOF.

For Stream sockets, the second return value would be invalid.

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.