| C<IO::Socket::IP> - Family-neutral IP socket supporting both IPv4 and IPv6 |
IO::Socket DEFAULT BEHAVIOURPeerHost AND LocalHost PARSINGIO::Socket::INET INCOMPATIBILITES
IO::Socket::IP - Family-neutral IP socket supporting both IPv4 and IPv6
use IO::Socket::IP;
my $sock = IO::Socket::IP->new(
PeerHost => "www.google.com",
PeerPort => "http",
Type => SOCK_STREAM,
) or die "Cannot construct socket - $@";
my $familyname = ( $sock->sockdomain == PF_INET6 ) ? "IPv6" :
( $sock->sockdomain == PF_INET ) ? "IPv4" :
"unknown";
printf "Connected to google via %s\n", $familyname;
This module provides a protocol-independent way to use IPv4 and IPv6 sockets,
intended as a replacement for the IO::Socket::INET manpage. Most constructor arguments
and methods are provided in a backward-compatible way. For a list of known
differences, see the IO::Socket::INET INCOMPATIBILITES section below.
It uses the getaddrinfo(3) function to convert hostnames and service names
or port numbers into sets of possible addresses to connect to or listen on.
This allows it to work for IPv6 where the system supports it, while still
falling back to IPv4-only on systems which don't.
IO::Socket DEFAULT BEHAVIOURBy placing -register in the import list, the IO::Socket manpage uses
IO::Socket::IP rather than IO::Socket::INET as the class that handles
PF_INET. IO::Socket will also use IO::Socket::IP rather than
IO::Socket::INET6 to handle PF_INET6, provided that the AF_INET6
constant is available.
Changing IO::Socket's default behaviour means that calling the
IO::Socket constructor with either PF_INET or PF_INET6 as the
Domain parameter will yield an IO::Socket::IP object.
use IO::Socket::IP -register;
my $sock = IO::Socket->new(
Domain => PF_INET6,
LocalHost => "::1",
Listen => 1,
) or die "Cannot create socket - $@\n";
print "Created a socket of type " . ref($sock) . "\n";
Note that -register is a global setting that applies to the entire program;
it cannot be applied only for certain callers, removed, or limited by lexical
scope.
Creates a new IO::Socket::IP object, containing a newly created socket
handle according to the named arguments passed. The recognised arguments are:
connect() to. The service name
may be given as a port number, as a decimal string.
IO::Socket::INET, these are accepted as synonyms for PeerHost and
PeerService respectively.
connect() to. This should be an
array of the form returned by Socket::getaddrinfo.
This parameter takes precedence over the Peer*, Family, Type and
Proto arguments.
bind() to.
IO::Socket::INET, these are accepted as synonyms for LocalHost and
LocalService respectively.
bind() to. This should be
an array of the form returned by Socket::getaddrinfo.
This parameter takes precedence over the Local*, Family, Type and
Proto arguments.
getaddrinfo (e.g. AF_INET, AF_INET6).
Normally this will be left undefined, and getaddrinfo will search using any
address family supported by the system.
getaddrinfo (e.g. SOCK_STREAM,
SOCK_DGRAM). Normally defined by the caller; if left undefined
getaddrinfo may attempt to infer the type from the service name.
'tcp', IPPROTO_TCP,
'udp',IPPROTO_UDP). Normally this will be left undefined, and either
getaddrinfo or the kernel will choose an appropriate value. May be given
either in string name or numeric form.
getaddrinfo() function. If not supplied, a
default of AI_ADDRCONFIG will be used.
These flags will be combined with AI_PASSIVE if the Listen argument is
given. For more information see the documentation about getaddrinfo() in
the the Socket manpage module.
accept method. The value given is used as the
listen(2) queue size.
SO_REUSEADDR sockopt
SO_REUSEPORT sockopt (not all OSes implement this sockopt)
SO_BROADCAST sockopt
For example, both options given below are equivalent to setting ReuseAddr.
Sockopts => [
[ SOL_SOCKET, SO_REUSEADDR ],
[ SOL_SOCKET, SO_REUSEADDR, pack( "i", 1 ) ],
]
IPV6_V6ONLY sockopt when creating PF_INET6 sockets
to the given value. If true, a listening-mode socket will only listen on the
AF_INET6 addresses; if false it will also accept connections from
AF_INET addresses.
If not defined, the socket option will not be changed, and default value set by the operating system will apply. For repeatable behaviour across platforms it is recommended this value always be defined for listening-mode sockets.
Note that not all platforms support disabling this option. Some, at least
OpenBSD and MirBSD, will fail with EINVAL if you attempt to disable it.
To determine whether it is possible to disable, you may use the class method
if( IO::Socket::IP->CAN_DISABLE_V6ONLY ) {
...
}
else {
...
}
If your platform does not support disabling this option but you still want to
listen for both AF_INET and AF_INET6 connections you will have to create
two listening sockets, one bound to each protocol.
IO::Socket::INET-style argument is ignored, except if it is defined
but false. See the IO::Socket::INET INCOMPATIBILITES section below.
However, the behaviour it enables is always performed by IO::Socket::IP.
connect() call
when in blocking mode. If missing, no timeout is applied other than that
provided by the underlying operating system. When in non-blocking mode this
parameter is ignored.
Note that if the hostname resolves to multiple address candidates, the same timeout will apply to each connection attempt individually, rather than to the operation as a whole. Further note that the timeout does not apply to the initial hostname resolve operation, if connecting by hostname.
This behviour is copied inspired by IO::Socket::INET; for more fine grained
control over connection timeouts, consider performing a nonblocking connect
directly.
If neither Type nor Proto hints are provided, a default of
SOCK_STREAM and IPPROTO_TCP respectively will be set, to maintain
compatibility with IO::Socket::INET. Other named arguments that are not
recognised are ignored.
If neither Family nor any hosts or addresses are passed, nor any
*AddrInfo, then the constructor has no information on which to decide a
socket family to create. In this case, it performs a getaddinfo call with
the AI_ADDRCONFIG flag, no host name, and a service name of "0", and
uses the family of the first returned result.
If the constructor fails, it will set $@ to an appropriate error message;
this may be from $! or it may be some other string; not every failure
necessarily has an associated errno value.
As a special case, if the constructor is passed a single argument (as
opposed to an even-sized list of key/value pairs), it is taken to be the value
of the PeerAddr parameter. This is parsed in the same way, according to the
behaviour given in the PeerHost AND LocalHost PARSING section below.
As well as the following methods, this class inherits all the methods in the IO::Socket manpage and the IO::Handle manpage.
Returns the hostname and service name of the local address (that is, the
socket address given by the sockname method).
If $numeric is true, these will be given in numeric form rather than being
resolved into names.
The following four convenience wrappers may be used to obtain one of the two
values returned here. If both host and service names are required, this method
is preferable to the following wrappers, because it will call
getnameinfo(3) only once.
Return the numeric form of the local address as a textual representation
Return the numeric form of the local port number
Return the resolved name of the local address
Return the resolved name of the local port number
Return the local address as a binary octet string
Returns the hostname and service name of the peer address (that is, the
socket address given by the peername method), similar to the
sockhost_service method.
The following four convenience wrappers may be used to obtain one of the two
values returned here. If both host and service names are required, this method
is preferable to the following wrappers, because it will call
getnameinfo(3) only once.
Return the numeric form of the peer address as a textual representation
Return the numeric form of the peer port number
Return the resolved name of the peer address
Return the resolved name of the peer port number
Return the peer address as a binary octet string
Returns a new the IO::Socket::INET manpage instance wrapping the same filehandle. This
may be useful in cases where it is required, for backward-compatibility, to
have a real object of IO::Socket::INET type instead of IO::Socket::IP.
The new object will wrap the same underlying socket filehandle as the
original, so care should be taken not to continue to use both objects
concurrently. Ideally the original $sock should be discarded after this
method is called.
This method checks that the socket domain is PF_INET and will throw an
exception if it isn't.
If the constructor is passed a defined but false value for the Blocking
argument then the socket is put into non-blocking mode. When in non-blocking
mode, the socket will not be set up by the time the constructor returns,
because the underlying connect(2) syscall would otherwise have to block.
The non-blocking behaviour is an extension of the IO::Socket::INET API,
unique to IO::Socket::IP, because the former does not support multi-homed
non-blocking connect.
When using non-blocking mode, the caller must repeatedly check for
writeability on the filehandle (for instance using select or IO::Poll).
Each time the filehandle is ready to write, the connect method must be
called, with no arguments. Note that some operating systems, most notably
MSWin32 do not report a connect() failure using write-ready; so you must
also select() for exceptional status.
While connect returns false, the value of $! indicates whether it should
be tried again (by being set to the value EINPROGRESS, or EWOULDBLOCK on
MSWin32), or whether a permanent error has occurred (e.g. ECONNREFUSED).
Once the socket has been connected to the peer, connect will return true
and the socket will now be ready to use.
Note that calls to the platform's underlying getaddrinfo(3) function may
block. If IO::Socket::IP has to perform this lookup, the constructor will
block even when in non-blocking mode.
To avoid this blocking behaviour, the caller should pass in the result of such
a lookup using the PeerAddrInfo or LocalAddrInfo arguments. This can be
achieved by using the Net::LibAsyncNS manpage, or the getaddrinfo(3) function can be
called in a child process.
use IO::Socket::IP; use Errno qw( EINPROGRESS EWOULDBLOCK );
my @peeraddrinfo = ... # Caller must obtain the getaddinfo result here
my $socket = IO::Socket::IP->new(
PeerAddrInfo => \@peeraddrinfo,
Blocking => 0,
) or die "Cannot construct socket - $@";
while( !$socket->connect and ( $! == EINPROGRESS || $! == EWOULDBLOCK ) ) {
my $wvec = '';
vec( $wvec, fileno $socket, 1 ) = 1;
my $evec = '';
vec( $evec, fileno $socket, 1 ) = 1;
select( undef, $wvec, $evec, undef ) or die "Cannot select - $!";
}
die "Cannot connect - $!" if $!;
...
The example above uses select(), but any similar mechanism should work
analogously. IO::Socket::IP takes care when creating new socket filehandles
to preserve the actual file descriptor number, so such techniques as poll
or epoll should be transparent to its reallocation of a different socket
underneath, perhaps in order to switch protocol family between PF_INET and
PF_INET6.
For another example using IO::Poll and Net::LibAsyncNS, see the
examples/nonblocking_libasyncns.pl file in the module distribution.
PeerHost AND LocalHost PARSINGTo support the IO::Socket::INET API, the host and port information may be
passed in a single string rather than as two separate arguments.
If either LocalHost or PeerHost (or their ...Addr synonyms) have any
of the following special forms then special parsing is applied.
The value of the ...Host argument will be split to give both the hostname
and port (or service name):
hostname.example.org:http # Host name 192.0.2.1:80 # IPv4 address [2001:db8::1]:80 # IPv6 address
In each case, the port or service name (e.g. 80) is passed as the
LocalService or PeerService argument.
Either of LocalService or PeerService (or their ...Port synonyms) can
be either a service name, a decimal number, or a string containing both a
service name and number, in a form such as
http(80)
In this case, the name (http) will be tried first, but if the resolver does
not understand it then the port number (80) will be used instead.
If the ...Host argument is in this special form and the corresponding
...Service or ...Port argument is also defined, the one parsed from
the ...Host argument will take precedence and the other will be ignored.
Utility method that provides the parsing functionality described above.
Returns a 2-element list, containing either the split hostname and port
description if it could be parsed, or the given address and undef if it was
not recognised.
IO::Socket::IP->split_addr( "hostname:http" )
# ( "hostname", "http" )
IO::Socket::IP->split_addr( "192.0.2.1:80" )
# ( "192.0.2.1", "80" )
IO::Socket::IP->split_addr( "[2001:db8::1]:80" )
# ( "2001:db8::1", "80" )
IO::Socket::IP->split_addr( "something.else" )
# ( "something.else", undef )
Utility method that performs the reverse of split_addr, returning a string
formed by joining the specified host address and port number. The host address
will be wrapped in [] brackets if required (because it is a raw IPv6
numeric address).
This can be especially useful when combined with the sockhost_service or
peerhost_service methods.
say "Connected to ", IO::Socket::IP->join_addr( $sock->peerhost_service );
IO::Socket::INET INCOMPATIBILITESMultiHomed is in fact implemented by
IO::Socket::IP as it is required to correctly support searching for a
useable address from the results of the getaddrinfo(3) call. The
constructor will ignore the value of this argument, except if it is defined
but false. An exception is thrown in this case, because that would request it
disable the getaddrinfo(3) search behaviour in the first place.
IO::Socket::IP implements both the Blocking and Timeout parameters,
but it implements the interaction of both in a different way.
In ::INET, supplying a timeout overrides the non-blocking behaviour,
meaning that the connect() operation will still block despite that the
caller asked for a non-blocking socket. This is not explicitly specified in
its documentation, nor does this author believe that is a useful behaviour -
it appears to come from a quirk of implementation.
In ::IP therefore, the Blocking parameter takes precedence - if a
non-blocking socket is requested, no operation will block. The Timeout
parameter here simply defines the maximum time that a blocking connect()
call will wait, if it blocks at all.
In order to specifically obtain the ``blocking connect then non-blocking send
and receive'' behaviour of specifying this combination of options to ::INET
when using ::IP, perform first a blocking connect, then afterwards turn the
socket into nonblocking mode.
my $sock = IO::Socket::IP->new(
PeerHost => $peer,
Timeout => 20,
) or die "Cannot connect - $@";
$sock->blocking( 0 );
This code will behave identically under both IO::Socket::INET and
IO::Socket::IP.
POSIX::dup2 upsets BSD's kqueue watchers, and if so,
consider what possible workarounds might be applied.
Paul Evans <leonerd@leonerd.org.uk>
| C<IO::Socket::IP> - Family-neutral IP socket supporting both IPv4 and IPv6 |