/ 
Socket-More-v0.4.3
River stage zero No dependents
/ Socket::More

NAME

Socket::More - List network interfaces and scope passive sockets to them

SYNOPSIS

Bring into your namespace.

use v5.36;
use Socket::More;

Simple list of all network interfaces:

#List basic interface information on all available interfaces
my @ifs=getifaddrs;
say $_->{name} for @ifs;

Flexible way to create interface scoped passive (listen) address across families. Special 'unix' interface for ease of use. All invalid combinations of family, port and paths are discarded:

	# Create passive (listening) sockets for selected interfaces
  #
	my @passive=sockaddr_passive {
		interface=>	["eth0", "unix"],
		port=>		[5566, 7788],
		path=> "path_to_sock"
	};
		
	#All invalid family/interface/port/path  combinations are filtered out
	#leaving only valid info for socket creation and binding:
  #
	for(@passive){
		say $_->{address};
		socket my $socket, $_->{family}, $_->{type}, 0;
		bind $socket $_->{addr};
	}

DESCRIPTION

At the surface level this module is a binding to getifaddrs, if_nametoindex, if_indextoname and if_nameindex to query the interfaces available on the host machine.

However its main purpose is to concisely generate data structures needed to bind multiple passive (listen) sockets scoped to an named interface. It implements the combinatorics, filtering of invalid combinations and a terse command line processing option to make configuring passive sockets easy.

It solves problems like this:

'listen on interfaces eth0 and eth1, using IPv6 and port numbers 9090
and 9091, but limit to link local addresses, and stream types'.

'listen on eth0 and unix, port 1000 and path test.sock, using datagram
type sockets,'.

'listen on all interfaces on port 8080 and 8081, but only on link local
ipv6 address'

It also makes it easy to generate 'random' ports to bind to, before your program binds, to aid in testing server scenarios.

All subroutines are exported, including all symbols from Socket.

Please see the API section for a complete listing.

MOTIVATION

I wanted an easy way to listen on a particular interface ONLY. The normal way of wild card addresses "0.0.0.0" or "::", will listen on all interfaces. Any restrictions on connecting sockets will either need to be implemented in the firewall or in application code accepting and then closing the connection. This is a waste of resources and a potential security problem.

Manually creating the multitude of potential addresses on the same interface (especially for IPv6) is a pain to maintain. This module reduces the effort by generating all combinations of parameters and then filters out what doesn't make sense and what you don't want. See sockaddr_passive below for more information.

API

getifaddrs

my @interfaces=getifaddrs;

Queries the OS via getifaddr for the list of interfaces currently active. Returns a list of hash references representing the network interfaces. The keys of these hashes include:

name

The text name of the interface

flags

Flags set on the interface

addr

Packed sockaddr structure suitable for use with bind

netmask

Packed sockaddr structure of the netmask

dstmask

Packed sockaddr structure of the dstmask

if_nametoindex

my $index=if_nametoindex($name);

Returns the index of an interface by name. If the interface is not found, returns 0 and sets $! with error code.

if_indextoname

my $name=if_indextoname($index);

Returns the name of an interface by index. If the index does not represent an interface, undef is returned and sets $! with error code

if_nameindex

my @pairs=if_nameindex;

Returns a list of key value pairs. The key is the interface index, and the value is the name of the interface.

Return undef on error and sets $! with error code.

family_to_string

my $string=family_to_string($family);

Returns a string label representing an address family $family. For example, calling with constant AF_INET, will return a string "AF_INET"

string_to_family

my @family=string_to_family($pattern);

Performs a match of all AF_.* names against $pattern. Returns a list of integer constants for the corresponding address family that matched. Returns an empty list if the patten/string does not match. The match is performed insensitive to case

For example calling with "INET" will return a list of two elements, AF_INET and AF_INET6.

This is useful for handling address families supplied from the command line, as abbreviated names can be matched.

sock_to_string

my $string=sock_to_string($type);

Returns a string label representing a socket type $type. For example, calling with the integer constant SOCK_STREAM, will return a string "SOCK_STREAM"

string_to_sock

my @type=string_to_family($string);

Performs a match of all SOCK_.* names against $pattern. Returns a list of integers for the corresponding socket types that matched. Returns an empty list if the patten/string does not match. The match is performed insensitive to case.

For example calling with "STREAM" will return a list of one element, SOCK_STREAM.

This is useful for handling address families supplied from the command line, as abbreviated names can be matched.

sockaddr_passive

my @interfaces=sockadd_passive $specification;

Returns a list of 'interface' structures (similar to getifaddr above) which provide meta data and packed address structures suitable for passive use (i.e bind) and matching the $specification. The resulting data is sorted by interface name, then by family and finally by type.

It has some overlapping function of getaddrinfo, however it is specifically for creating addresses for binding, allows the use of interface names and operates with UNIX domain configurations through a synthetic 'unix' interface.

A specification hash has optional keys which dictate what addresses are generated and filtered:

{
	interface=>"en",
	family=>"INET",
	port=>[1234]
	...
}

The only required keys are port and/or path. These are used in the address generation and not as a filter. Without at least one of these keys, no results will be generated.

Other keys like interface, family and type for example are used to restrict addresses created to the match

Keys like address and group are a filter which are directly matched against the address and group.

Keys themselves can be shortened all the way down to the shortest unique substring. So instead of 'interface', it could be 'inter', 'int' or just 'i' for example. This aids in usage from the command line. The shortest unique keys are:

{
	i=>...		#interface
	f=>...		#family
	po=>...		#port
	pa=>...		#path
	a=>...		#address
	t=>...		#type
	g=>...		#group
}

It can include the following keys:

interface
examples: 
interface=>"eth0"
interface=>"eth\d*";
interface=>["eth0", "lo"];
interface=>"unix";
interface=>["unix", "lo"];

A string or array ref of strings which are used as regex to match interface names currently available.

familiy
examples: family=>AF_INET family=>[AF_INET, AF_INET6, AF_UNIX]

A integer or array ref of integers representing the family type an interface supports.

From v0.4.0: Also can be a string or array ref of strings, which are matched against supported families. See parse_passive_spec for matching details

type
examples: type=>SOCK_STREAM type=>[SOCK_STREAM, SOCK_DGRAM]

A integer or array ref of integers representing the socket type an interface supports.

From v0.4.0: Also can be a string or array ref of strings, which are matched against supported socket types. See parse_passive_spec for matching details

port
examples: port=>55554 port=>[12345,12346]

The ports used in generating a passive address. Only applied to AF_INET* families. Ignored for others.

Either port or path are required, otherwise no addresses will be generated.

path
examples: path=>"path_to_socket.sock" path=>["path_to_socket1.sock",
"path_to_socket2.sock"]

The path used in generating a passive address. Only applied to AF_UNIX families. Ignored for others.

Either port or path are required, otherwise no addresses will be generated.

NOTE The actual path resulting from the specification will have a '_D' or '_S' appended to the path. This is done to ensure sockets of different type don't attempt to use the same path.

address
exmples: 
	address=>"192\.168\.1\.1" 
	address=>"169\.254\."

As string used to match the textual representation of an address. In the special case of '0.0.0.0" or "::", any interface specification is ignored.

group
examples:
	group=>"PRIVATE'

The group the address belongs to as per Net::IP

data
examples: 
data=>[$scalar]
data=>[{ ca=>$ca_path, pkey=>$p_path}]

A user field which will be included in each item in the output list.

NOTE It is recommended this value is an array ref, wrapping actual data. This makes it more consistent when the data key is parsed from the command line

parse_passive_spec

my @spec=parse_passive_spec($string);

Parses a concise string intended to be supplied as a command line argument. The string consists of one or more fields separated by commas.

The fields are in key value pairs in the form

key=value

key can be any key used in a specification for sockaddr_passive, and value is interpreted as a path, number or a string (regex), depending on the key.

port and path keys take literal values.

family and type keys take regex values, which match against the family/type names (using string_to_sock and string_to_family) and are replaced with the integer values internally.

Other keys treat the value as a string/regex to match against.

The keys can be used repeatedly within multiple fields. For example that means the following will match interfaces eth0, eth1 and lo.

in=>eth0,port=1000,in='lo|eth1'

Only the first "=" within a field is split. this allows the data field itself to take more key value pairs:

eg:
data=key1=value,data=key2=another
data=ca=ca_path.pem,data=key=private.pem

NOTE Because repeat data keys can be used, the specification generated from parse_passive_spec will contain a data key with an array as its value.

For example, the following parse a sockaddr_passive specification which would match SOCK_STREAM sockets, for both AF_INET and AF_INET6 families, on all available interfaces.

family=INET,type=STREAM #Full key name
f=INET,t=STREAM		#Shortest unique string for keys

The special case of a field not in key value format (i.e. with out a '='), is interpreted as the plack compatible listen switch argument.

HOST:PORT		#INET/INET6 address and port
:PORT 			#wildcard address and port
PATH			#UNIX socket path

The HOST portion is assinged to the address field. The PORT portion is assigned to the port field. If a PORT is specified without a HOST, then the address field is set to ["0.0.0.0", "::"] which disables interface matching, but will listen on all INET addresses.

NOTE This behaviour may change in later versions, as "::" supports both INET and INET6.

NOTE to specify an IPv6 literal on the command line, it is contained in a pair of [] and will need to be escaped or quoted in the shell

socket

socket $socket, $domain_or_addr, $type, $proto


example:
	die "$!" unless socket my $socket, AF_INET, SOCK_STREAM,0;

	
	die "$!" unless socket my $socket, $sockaddr, SOCK_STREAM,0;

A wrapper around CORE::socket. It checks if the DOMAIN is a number. If so, it simply calls CORE::socket with the supplied arguments.

Otherwise it assumes DOMAIN is a packed sockaddr structure and extracts the domain/family field using sockaddr_family. This value is then used as the DOMAIN value in a call to CORE::socket.

Return values are as per CORE::socket. Please refer to "perldoc -f socket" for more.

has_IPv4_interface

has_IPv4_interface;

Returns true if at least one IPv4 interface was found. False otherwise.

has_IPv6_interface

has_IPv6_interface;

Returns true if at least one IPv6 interface was found. False otherwise.

reify_ports

reify_ports $specs, ...

example:
  reify_ports {address=>"127.0.0.1", port=>0}

Iterates through list of specifications and replacing port fields equal to 0 (any port), with a 'random' one supplied by the operating system. This performs a sockaddr_passive call to to 'flatten' any internal structures in the specifications provided.

This works by taking the first entry which results in a 0 port number, creating a socket and binding it. The 0 port will result in the OS choosing a port for use. The resulting port is extracted from the socket (getsocketname) and replaces the 0 port value in all the specification entries. The socket has SO_REUSEADDR applied to ensure it can be bound again immediately.

If the specifications request two or more 0 ports in otherwise identical specifications, it is up the user to choose how to handle any duplicate bind complications (i.e SO_REUSEPORT)

NOTE: There is a chance that another program can use the port number returned after a call to reify_ports.

NOTE: The interface/address tested to generate the random port might return a port which is already in use on other interfaces.

reify_ports_unshared

  reify_ports_chaos $specs, ...

example:
  reify_ports {address=>"127.0.0.1", port=>[0,0]};
  reify_ports {address=>"127.0.0.1", port=>0}, {port=>0};

Operates like reify_ports with the exception that all 0 port entries in the specifications cause a query to the OS. The port numbers are not explicitly 'shared' between specifications, thus returning potentially (most likely) different port numbers for each entry.

EXAMPLES

Please checkout 'cli.pl' in the examples directory of this distribution. It demonstrates many of the features of this module by using the sockaddr_passive, parse_passive_spec, family_to_string and sock_to_string functions. It requires Text::Table in addition to this module.

It takes user input from the command line using one or more -l parameters via Getopt::Long. These are parsed into passive specifications, which are then executed to generate list of passive structures matching the specification. The results are converted into nice text table output.

The following shows the example outputs running this program with different inputs.

Run1

Any interface, AF_INET6 only, stream or datagram on port 1000:

perl examples/cli.pl -l '[::]':1000

Interface Address Family   Group       Port Path Type	     Data
::        ::      AF_INET6 UNSPECIFIED 1000      SOCK_STREAM
::        ::      AF_INET6 UNSPECIFIED 1000      SOCK_DGRAM

Run2

Any interface, AF_INET only, stream or datagram on port 1000:

->perl examples/cli.pl -l 0.0.0.0:1000
Interface Address Family  Group   Port Path Type	Data
0.0.0.0   0.0.0.0 AF_INET PRIVATE 1000      SOCK_STREAM
0.0.0.0   0.0.0.0 AF_INET PRIVATE 1000      SOCK_DGRAM

Run3

Any interface, AF_INET only, stream or datagram on port 1000, with data:

perl examples/cli.pl -l 0.0.0.0:1000,data='ca_path=ca_path.pem;key=key_path'
Interface Address Family  Group   Port Path Type        Data
0.0.0.0   0.0.0.0 AF_INET PRIVATE 1000      SOCK_STREAM ca_path=ca_path.pem;key=key_path
0.0.0.0   0.0.0.0 AF_INET PRIVATE 1000      SOCK_DGRAM  ca_path=ca_path.pem;key=key_path

Run4

On interface en0, port 1000, stream or datagram types and only private or link local addresses:

perl examples/cli.pl -l interface=en0,port=1000,group='pri|link'

Interface Address                   Family   Group              Port Path Type        Data
en0       192.168.1.103             AF_INET  PRIVATE            1000      SOCK_STREAM
en0       192.168.1.103             AF_INET  PRIVATE            1000      SOCK_DGRAM 
en0       fe80::1086:a38e:8f5d:38e2 AF_INET6 LINK-LOCAL-UNICAST 1000      SOCK_STREAM
en0       fe80::1086:a38e:8f5d:38e2 AF_INET6 LINK-LOCAL-UNICAST 1000      SOCK_DGRAM

Run5

On interface en0,lo and unix, port 1000, path mypath.sock, and stream type only

perl examples/cli.pl -l interface='en0|lo|unix',port=1000,path=mypath.sock,type=stream

Interface Address                   Family   Group              Port Path          Type        Data
en0       192.168.1.103             AF_INET  PRIVATE            1000               SOCK_STREAM
en0       fe80::1086:a38e:8f5d:38e2 AF_INET6 LINK-LOCAL-UNICAST 1000               SOCK_STREAM
lo0       fe80::1                   AF_INET6 LINK-LOCAL-UNICAST 1000               SOCK_STREAM
unix      mypath.sock_S             AF_UNIX  UNIX                    mypath.sock_S SOCK_STREAM

Run6

Shortened keys. Multiple listeners on command line:

First specification: Interface en0, port 1000, only AF_INET and stream

Second specification: Interface lo or unix, AF_INET or UNIX types, po 2000 for inet and path test.sock for unix, datagram type only

perl examples/cli.pl -l i='en0',po=1000,f='inet$',t=stream -l i='lo|unix',f='inet$|unix',po=2000,pa="test.sock",t=dgram

Interface Address       Family  Group    Port Path        Type 	      Data
en0       192.168.1.103 AF_INET PRIVATE  1000             SOCK_STREAM
lo0       127.0.0.1     AF_INET LOOPBACK 2000             SOCK_DGRAM
unix      test.sock_D   AF_UNIX UNIX          test.sock_D SOCK_DGRAM

RUN7

Interface en0 and lo, port 1010, private or link local group, multiple data keys

examples/cli.pl -l in=en0,in=lo,po=1010,gr='PRI|link',data=ca=test,data=key=path

Interface Address                   Family   Group              Port Path Type        Data            
en0       192.168.1.103             AF_INET  PRIVATE            1010      SOCK_STREAM ca=test,key=path
en0       192.168.1.103             AF_INET  PRIVATE            1010      SOCK_DGRAM  ca=test,key=path
en0       fe80::1086:a38e:8f5d:38e2 AF_INET6 LINK-LOCAL-UNICAST 1010      SOCK_STREAM ca=test,key=path
en0       fe80::1086:a38e:8f5d:38e2 AF_INET6 LINK-LOCAL-UNICAST 1010      SOCK_DGRAM  ca=test,key=path
lo0       fe80::1                   AF_INET6 LINK-LOCAL-UNICAST 1010      SOCK_STREAM ca=test,key=path
lo0       fe80::1                   AF_INET6 LINK-LOCAL-UNICAST 1010      SOCK_DGRAM  ca=test,key=path

TODO

Network interface queries for byte counts, rates.. etc
Expand address family types support(i.e link)
Network change events/notifications

SEE ALSO

Other modules provide network interface queries: Net::Interface seems broken at the time of writing IO::Interface works with IPv4 addressing only?

AUTHOR

Ruben Westerberg, <drclaw@mac.com<gt>

REPOSITORTY and BUGS

Please report any bugs via git hub: http://github.com/drclaw1394/perl-socket-more

COPYRIGHT AND LICENSE

Copyright (C) 2023 by Ruben Westerberg

This library is free software; you can redistribute it and/or modify it under the same terms as Perl or the MIT license.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.