Z-IO- Simple and high performance IO toolkit for Haskell
Copyright(c) Winterland 2018
Safe HaskellNone



This module provides getAddrInfo and getNameInfo. getnameinfo and getaddrinfo equivalent.


name to ip

getAddrInfo Source #


:: Maybe AddrInfo

preferred socket type or protocol

-> HostName

host name to look up

-> 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 SocketAddr values that you can use to init TCP connection.

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 non empty 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) "" "http"
>>> addrAddress addr

type HostName = CBytes 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., "".

type ServiceName = CBytes Source #

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

data AddrInfoFlag Source #

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



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.)


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


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


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


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


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


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

addrInfoFlagImplemented :: AddrInfoFlag -> Bool Source #

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

data AddrInfo Source #

Address info


Instances details
Eq AddrInfo Source # 
Instance details

Defined in Z.IO.Network.DNS

Show AddrInfo Source # 
Instance details

Defined in Z.IO.Network.DNS

Storable AddrInfo Source # 
Instance details

Defined in Z.IO.Network.DNS

defaultHints :: AddrInfo Source #

Default hints for address lookup with getAddrInfo.

>>> addrFlags defaultHints
>>> addrFamily defaultHints
>>> addrSocketType defaultHints
>>> addrProtocol defaultHints

followAddrInfo :: Ptr AddrInfo -> IO [AddrInfo] Source #

Peek addrinfo linked list.

ip to name

getNameInfo Source #


:: [NameInfoFlag]

flags to control lookup behaviour

-> Bool

whether to look up a hostname

-> Bool

whether to look up a service name

-> SocketAddr

the address to look up

-> IO (HostName, 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) "" "http"
>>> getNameInfo [NI_NUMERICHOST, NI_NUMERICSERV] True True $ addrAddress addr
("", "80")

data NameInfoFlag Source #

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



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.


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


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


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.


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