Portability | portable |
---|---|
Stability | provisional |
Maintainer | libraries@haskell.org |
The Network.Socket module is for when you want full control over sockets. Essentially the entire C socket API is exposed through this module; in general the operations follow the behaviour of the C functions of the same name (consult your favourite Unix networking book).
A higher level interface to networking operations is provided through the module Network.
- data Socket = MkSocket CInt Family SocketType ProtocolNumber (MVar SocketStatus)
- data Family
- data SocketType
- data SockAddr
- data SocketStatus
- = NotConnected
- | Bound
- | Listening
- | Connected
- | ConvertedToHandle
- | Closed
- type HostAddress = Word32
- type HostAddress6 = (Word32, Word32, Word32, Word32)
- type FlowInfo = Word32
- type ScopeID = Word32
- data ShutdownCmd
- type ProtocolNumber = CInt
- defaultProtocol :: ProtocolNumber
- newtype PortNumber = PortNum Word16
- type HostName = String
- type ServiceName = String
- data AddrInfo = AddrInfo {}
- data AddrInfoFlag
- = AI_ADDRCONFIG
- | AI_ALL
- | AI_CANONNAME
- | AI_NUMERICHOST
- | AI_NUMERICSERV
- | AI_PASSIVE
- | AI_V4MAPPED
- addrInfoFlagImplemented :: AddrInfoFlag -> Bool
- defaultHints :: AddrInfo
- getAddrInfo :: Maybe AddrInfo -> Maybe HostName -> Maybe ServiceName -> IO [AddrInfo]
- data NameInfoFlag
- = NI_DGRAM
- | NI_NAMEREQD
- | NI_NOFQDN
- | NI_NUMERICHOST
- | NI_NUMERICSERV
- getNameInfo :: [NameInfoFlag] -> Bool -> Bool -> SockAddr -> IO (Maybe HostName, Maybe ServiceName)
- socket :: Family -> SocketType -> ProtocolNumber -> IO Socket
- socketPair :: Family -> SocketType -> ProtocolNumber -> IO (Socket, Socket)
- connect :: Socket -> SockAddr -> IO ()
- bindSocket :: Socket -> SockAddr -> IO ()
- listen :: Socket -> Int -> IO ()
- accept :: Socket -> IO (Socket, SockAddr)
- getPeerName :: Socket -> IO SockAddr
- getSocketName :: Socket -> IO SockAddr
- getPeerCred :: Socket -> IO (CUInt, CUInt, CUInt)
- socketPort :: Socket -> IO PortNumber
- socketToHandle :: Socket -> IOMode -> IO Handle
- sendTo :: Socket -> String -> SockAddr -> IO Int
- sendBufTo :: Socket -> Ptr a -> Int -> SockAddr -> IO Int
- recvFrom :: Socket -> Int -> IO (String, Int, SockAddr)
- recvBufFrom :: Socket -> Ptr a -> Int -> IO (Int, SockAddr)
- send :: Socket -> String -> IO Int
- recv :: Socket -> Int -> IO String
- recvLen :: Socket -> Int -> IO (String, Int)
- inet_addr :: String -> IO HostAddress
- inet_ntoa :: HostAddress -> IO String
- shutdown :: Socket -> ShutdownCmd -> IO ()
- sClose :: Socket -> IO ()
- sIsConnected :: Socket -> IO Bool
- sIsBound :: Socket -> IO Bool
- sIsListening :: Socket -> IO Bool
- sIsReadable :: Socket -> IO Bool
- sIsWritable :: Socket -> IO Bool
- data SocketOption
- = DummySocketOption__
- | Debug
- | ReuseAddr
- | Type
- | SoError
- | DontRoute
- | Broadcast
- | SendBuffer
- | RecvBuffer
- | KeepAlive
- | OOBInline
- | TimeToLive
- | MaxSegment
- | NoDelay
- | Linger
- | RecvLowWater
- | SendLowWater
- | RecvTimeOut
- | SendTimeOut
- getSocketOption :: Socket -> SocketOption -> IO Int
- setSocketOption :: Socket -> SocketOption -> Int -> IO ()
- sendFd :: Socket -> CInt -> IO ()
- recvFd :: Socket -> IO CInt
- sendAncillary :: Socket -> Int -> Int -> Int -> Ptr a -> Int -> IO ()
- recvAncillary :: Socket -> Int -> Int -> IO (Int, Int, Ptr a, Int)
- aNY_PORT :: PortNumber
- iNADDR_ANY :: HostAddress
- iN6ADDR_ANY :: HostAddress6
- sOMAXCONN :: Int
- sOL_SOCKET :: Int
- sCM_RIGHTS :: Int
- maxListenQueue :: Int
- withSocketsDo :: IO a -> IO a
- fdSocket :: Socket -> CInt
- mkSocket :: CInt -> Family -> SocketType -> ProtocolNumber -> SocketStatus -> IO Socket
- packFamily :: Family -> CInt
- unpackFamily :: CInt -> Family
- packSocketType :: SocketType -> CInt
- throwSocketErrorIfMinus1_ :: Num a => String -> IO a -> IO ()
Types
This data type might have different constructors depending on what is supported by the operating system.
data SocketType Source
Socket Types.
This data type might have different constructors depending on what is supported by the operating system.
data SocketStatus Source
type HostAddress = Word32Source
type ProtocolNumber = CIntSource
defaultProtocol :: ProtocolNumberSource
This is the default protocol for a given service.
newtype PortNumber Source
Address operations
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 = StringSource
data AddrInfoFlag Source
Flags that control the querying behaviour of getAddrInfo
.
addrInfoFlagImplemented :: AddrInfoFlag -> BoolSource
Indicate whether the given AddrInfoFlag
will have any effect on
this system.
defaultHints :: AddrInfoSource
Default hints for address lookup with getAddrInfo
. The values
of the addrAddress
and addrCanonName
fields are undefined
,
and are never inspected by getAddrInfo
.
:: 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
bindSocket
.
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:
myHints = defaultHints { addrFlags = [AI_ADDRCONFIG, AI_CANONNAME] }
Values for addrFlags
control query behaviour. The supported
flags are as follows:
AI_PASSIVE
- If no
HostName
value is provided, the network address in eachSockAddr
will be left as a wild card, i.e. as eitheriNADDR_ANY
oriN6ADDR_ANY
. This is useful for server applications that will accept connections from any client. AI_CANONNAME
- The
addrCanonName
field of the first returnedAddrInfo
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.
Note: Although the following flags are required by RFC 3493, they
may not have an effect on all platforms, because the underlying
network stack may not support them. To see whether a flag from the
list below will have any effect, call addrInfoFlagImplemented
.
AI_NUMERICSERV
- The
ServiceName
argument must be a port number in string form, and service name lookups will not be attempted. 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. AI_V4MAPPED
- If an IPv6 lookup is performed, and no IPv6 addresses are found, IPv6-mapped IPv4 addresses will be returned.
AI_ALL
- If
AI_ALL
is specified, return all matching IPv6 and IPv4 addresses. Otherwise, this flag has no effect.
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.
Example:
let hints = defaultHints { addrFlags = [AI_ADDRCONFIG, AI_CANONNAME] }
addrs <- getAddrInfo (Just hints) (Just www.haskell.org) (Just http)
let addr = head addrs
sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
connect sock (addrAddress addr)
data NameInfoFlag Source
:: [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. The
supported flags are as follows:
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.
NI_NAMEREQD
- If the hostname cannot be looked up, an IO error is thrown.
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.
Hostname and service name lookups can be expensive. You can
specify which lookups to perform via the two Bool
arguments. If
one of these is False
, the corresponding value in the returned
tuple will be Nothing
, and no lookup will be performed.
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
Socket operations
socket :: Family -> SocketType -> ProtocolNumber -> IO SocketSource
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, the IPv6Only
socket option is set to 0
so that both IPv4 and IPv6 can be handled with one socket.
socketPair :: Family -> SocketType -> ProtocolNumber -> IO (Socket, Socket)Source
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.
listen :: Socket -> Int -> IO ()Source
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)Source
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.
getPeerName :: Socket -> IO SockAddrSource
getSocketName :: Socket -> IO SockAddrSource
getPeerCred :: Socket -> IO (CUInt, CUInt, CUInt)Source
Returns the processID, userID and groupID of the socket's peer.
Only available on platforms that support SO_PEERCRED on domain sockets.
socketPort :: Socket -> IO PortNumberSource
socketToHandle :: Socket -> IOMode -> IO HandleSource
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
.
Sending and receiving data
Do not use the send
and recv
functions defined in this module
in new code, as they incorrectly represent binary data as a Unicode
string. As a result, these functions are inefficient and may lead
to bugs in the program. Instead use the send
and recv
functions defined in the Network.Socket.ByteString
module.
sendTo :: Socket -> String -> SockAddr -> IO IntSource
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)
sendBufTo :: Socket -> Ptr a -> Int -> SockAddr -> IO IntSource
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.
recvFrom :: Socket -> Int -> IO (String, Int, SockAddr)Source
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)
recvBufFrom :: Socket -> Ptr a -> Int -> IO (Int, SockAddr)Source
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)
send :: Socket -> String -> IO IntSource
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.
recv :: Socket -> Int -> IO StringSource
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.
inet_addr :: String -> IO HostAddressSource
inet_ntoa :: HostAddress -> IO StringSource
shutdown :: Socket -> ShutdownCmd -> IO ()Source
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.
sClose :: Socket -> IO ()Source
Close the socket. All future operations on the socket object will fail. The remote end will receive no more data (after queued data is flushed).
Predicates on sockets
sIsConnected :: Socket -> IO BoolSource
sIsListening :: Socket -> IO BoolSource
sIsReadable :: Socket -> IO BoolSource
sIsWritable :: Socket -> IO BoolSource
Socket options
data SocketOption Source
getSocketOption :: Socket -> SocketOption -> IO IntSource
setSocketOption :: Socket -> SocketOption -> Int -> IO ()Source
File descriptor transmission
Special constants
iNADDR_ANY :: HostAddressSource
The IPv4 wild card address.
iN6ADDR_ANY :: HostAddress6Source
The IPv6 wild card address.
Initialisation
withSocketsDo :: IO a -> IO aSource
On Windows operating systems, the networking subsystem has to be
initialised using withSocketsDo
before any networking operations can
be used. eg.
main = withSocketsDo $ do {...}
Although this is only strictly necessary on Windows platforms, it is harmless on other platforms, so for portability it is good practice to use it all the time.
Very low level operations
mkSocket :: CInt -> Family -> SocketType -> ProtocolNumber -> SocketStatus -> IO SocketSource
Internal
The following are exported ONLY for use in the BSD module and should not be used anywhere else.
packFamily :: Family -> CIntSource
unpackFamily :: CInt -> FamilySource