| Copyright | (c) The University of Glasgow 2001 |
|---|---|
| License | BSD-style (see the file libraries/network/LICENSE) |
| Maintainer | libraries@haskell.org |
| Stability | provisional |
| Portability | portable |
| Safe Haskell | None |
| Language | Haskell98 |
Network
Contents
Description
This module is kept for backwards-compatibility. New users are encouraged to use Network.Socket instead.
Network was intended as a "higher-level" interface to networking facilities, and only supports TCP.
Synopsis
- data Socket
- data PortID
- type HostName = String
- data PortNumber
- withSocketsDo :: IO a -> IO a
- listenOn :: PortID -> IO Socket
- accept :: Socket -> IO (Handle, HostName, PortNumber)
- sClose :: Socket -> IO ()
- connectTo :: HostName -> PortID -> IO Handle
- sendTo :: HostName -> PortID -> String -> IO ()
- recvFrom :: HostName -> PortID -> IO String
- socketPort :: Socket -> IO PortID
Basic data types
Represents a socket. The fields are, respectively:
- File descriptor
- Socket family
- Socket type
- Protocol number
- Status flag
If you are calling the MkSocket constructor directly you should ensure
you have called withSocketsDo and that the file descriptor is
in non-blocking mode. See setNonBlockIfNeeded.
Sockets are not GCed unless they are closed by close.
Constructors
| Service String | |
| PortNumber PortNumber | |
| UnixSocket String |
type HostName = String Source #
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".
data PortNumber Source #
Use the Num instance (i.e. use a literal) to create a
PortNumber value with the correct network-byte-ordering. You
should not use the PortNum constructor. It will be removed in the
next release.
>>>1 :: PortNumber1>>>read "1" :: PortNumber1
Instances
Initialisation
withSocketsDo :: IO a -> IO a Source #
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).
Server-side connections
Creates the server side socket which has been bound to the specified port.
maxListenQueue (typically 128) is specified to the listen queue.
This is good enough for normal network servers but is too small
for high performance servers.
To avoid the "Address already in use" problems,
the ReuseAddr socket option is set on the listening socket.
If available, the IPv6Only socket option is set to 0
so that both IPv4 and IPv6 can be accepted with this socket.
If you don't like the behavior above, please use the lower level
listen instead.
Arguments
| :: Socket | Listening Socket |
| -> IO (Handle, HostName, PortNumber) | Triple of: read/write |
Accept a connection on a socket created by listenOn. Normal
I/O operations (see System.IO) can be used on the Handle
returned to communicate with the client.
Notice that although you can pass any Socket to Network.accept,
only sockets of either AF_UNIX, AF_INET, or AF_INET6 will work
(this shouldn't be a problem, though). When using AF_UNIX, HostName
will be set to the path of the socket and PortNumber to -1.
sClose :: Socket -> IO () Source #
Close the socket. Sending data to or receiving data from closed socket may lead to undefined behaviour.
Client-side connections
Simple sending and receiving
Send and receive data from/to the given host and port number. These
should normally only be used where the socket will not be required for
further calls. Also, note that due to the use of hGetContents in recvFrom
the socket will remain open (i.e. not available) even if the function already
returned. Their use is strongly discouraged except for small test-applications
or invocations from the command line.
Miscellaneous
Networking Issues
Buffering
The Handle returned by connectTo and accept is NoBuffering by
default. For an interactive application you may want to set the
buffering mode on the Handle to
LineBuffering or BlockBuffering, like so:
h <- connectTo host port hSetBuffering h LineBuffering