network-2.2.1.7: Networking-related facilities

Portabilityportable
Stabilityprovisional
Maintainerlibraries@haskell.org

Network.Socket

Contents

Description

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.

Synopsis

Types

data Socket

Instances

Eq Socket 
Show Socket 
Typeable Socket 

data Family

This data type might have different constructors depending on what is supported by the operating system.

Instances

Eq Family 
Ord Family 
Read Family 
Show Family 

data SocketType

Socket Types.

This data type might have different constructors depending on what is supported by the operating system.

Instances

Eq SocketType 
Ord SocketType 
Read SocketType 
Show SocketType 
Typeable SocketType 

type HostAddress = Word32

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

type FlowInfo = Word32

type ScopeID = Word32

data ShutdownCmd

Instances

Typeable ShutdownCmd 

type ProtocolNumber = CInt

defaultProtocol :: ProtocolNumber

This is the default protocol for a given service.

newtype PortNumber

Constructors

PortNum Word16 

Instances

Enum PortNumber 
Eq PortNumber 
Integral PortNumber 
Num PortNumber 
Ord PortNumber 
Real PortNumber 
Show PortNumber 
Typeable PortNumber 
Storable PortNumber 

Address operations

type HostName = String

type ServiceName = String

data AddrInfo

Instances

Eq AddrInfo 
Show AddrInfo 
Typeable AddrInfo 
Storable AddrInfo 

data AddrInfoFlag

Flags that control the querying behaviour of getAddrInfo.

Instances

addrInfoFlagImplemented :: AddrInfoFlag -> Bool

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

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.

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 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 each SockAddr will be left as a wild card, i.e. as either iNADDR_ANY or iN6ADDR_ANY. This is useful for server applications that will accept connections from any client.
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.

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)

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. 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

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

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

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

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

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

Only available on platforms that support SO_PEERCRED on domain sockets.

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.

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

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

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

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

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

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 ()

Closes a socket

Predicates on sockets

sIsConnected :: Socket -> IO Bool

sIsBound :: Socket -> IO Bool

sIsListening :: Socket -> IO Bool

sIsReadable :: Socket -> IO Bool

sIsWritable :: Socket -> IO Bool

Socket options

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

File descriptor transmission

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)

Special Constants

iNADDR_ANY :: HostAddress

The IPv4 wild card address.

iN6ADDR_ANY :: HostAddress6

The IPv6 wild card address.

sOMAXCONN :: Int

sOL_SOCKET :: Int

sCM_RIGHTS :: Int

Initialisation

withSocketsDo :: IO a -> IO a

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

fdSocket :: Socket -> CInt

Internal

The following are exported ONLY for use in the BSD module and should not be used anywhere else.

packFamily :: Family -> CInt

unpackFamily :: CInt -> Family

throwSocketErrorIfMinus1_

Arguments

:: Num a 
=> String

textual description of the location

-> IO a

the IO operation to be executed

-> IO () 

Throw an IOError corresponding to the current socket error if the IO action returns a result of -1. Discards the result of the IO action after error handling.