Socket::More - Scoped listening/passive addresses and network utility routines
Bring into your namespace.
use v5.36; use Socket::More;
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}, $_->{socktype}, 0; bind $socket $_->{addr}; }
Please see EXAMPLES section for more.
Intended as an alternative for Socket, implementing only 'modern subset' of routines. It providing extra routines to make listening addresses easy, to solve 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 is a umbrella package, which reexports Socket::More::Constants, Socket::More::Lookup and Socket::More::Interface for you.
It also makes it easy to generate 'random' ports to bind to, before your program binds, to aid in testing server scenarios.
Note this is a subset of Socket functionality. The 'old school' inet_* functions are deliberately not included, to encourage the usage of getnameinfo/getaddrinfo.
From version v0.5.0, the module has been decomposed to to separate modules on CPAN for targeted usage:
socket
Contains all the networking constants (ie AF_INET, NI_NUMERICHOST, etc) for your platform.
AF_INET
NI_NUMERICHOST
Implements and exports getaddrinfo, getnameinfo and gai_strerror, with a different calling convention then Perl core Socket implementation. More like sysread convention
getaddrinfo
getnameinfo
gai_strerror
sysread
Implements and exports getifaddrs, if_nametoindex, if_indextoname and if_nameindex to query the interfaces of your system
getifaddrs
if_nametoindex
if_indextoname
if_nameindex
Other packages/distributions not reexported but part of the family:
Non blocking and event loop integration of system resolver functions.
Grouping information on IP addresses
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.
sockaddr_passive
From version v0.5.0 the structure of the module has been refactored into other modules. The same API is accessible from this module, as it imports them and reexports their subroutines/constants. If you don't need the easy listening features of this module, then you can use these modules independently.
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"
$family
"AF_INET"
my @family=string_to_family($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
$pattern
For example calling with "INET" will return a list of two elements, AF_INET and AF_INET6.
"INET"
AF_INET6
This is useful for handling address families supplied from the command line, as abbreviated names can be matched.
my $string=socktype_to_string($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"
$type
SOCK_STREAM
"SOCK_STREAM"
my @type=string_to_socktype($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.
"STREAM"
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.
$specification
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.
From v0.5.0 the results will return interface information in an addition field.
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.
port
path
Other keys like interface, family and socktype for example are used to restrict addresses created to the match
interface
family
socktype
Keys like address and group are a filter which are directly matched against the address and group.
address
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 s=>... #socktype g=>... #group }
It can include the following keys:
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.
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
parse_passive_spec
examples: socktype=>SOCK_STREAM socktype=>[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
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.
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.
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.
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.
examples: group=>"PRIVATE'
The group the address belongs to as per Net::IP
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
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.
key
value
port and path keys take literal values.
family and socktype keys take regex values, which match against the family/socktype names (using string_to_sock and string_to_family) and are replaced with the integer values internally.
string_to_sock
string_to_family
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.
data
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,socktype=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.
HOST
PORT
["0.0.0.0", "::"]
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, $domain, $socktype, $proto socket $socket, $hash example: die "$!" unless socket my $socket, AF_INET, SOCK_STREAM,0; die "$!" unless socket my $socket, {family=>AF_INET, protocol=>0, socktype=>SOCK_STREAM};
A wrapper around CORE::socket. It checks if the DOMAIN is a number. If so, it simply calls CORE::socket with the supplied arguments.
CORE::socket
DOMAIN
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.
sockaddr_family
Return values are as per CORE::socket. Please refer to "perldoc -f socket" for more.
has_IPv4_interface;
Returns true if at least one IPv4 interface was found. False otherwise.
has_IPv6_interface;
Returns true if at least one IPv6 interface was found. False otherwise.
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.
SO_REUSEADDR
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)
SO_REUSEPORT
NOTE: There is a chance that another program can use the port number returned after a call to reify_ports.
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_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.
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.
family_to_string
sock_to_string
Text::Table
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.
-l
The following shows the example outputs running this program with different inputs.
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
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
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
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
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,socktype=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
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
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
Other modules provide network interface queries: Net::Interface seems broken at the time of writing IO::Interface works with IPv4 addressing only?
Ruben Westerberg, <drclaw@mac.com<gt>
Please report any bugs via git hub: http://github.com/drclaw1394/perl-socket-more
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.
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.
To install Socket::More, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Socket::More
CPAN shell
perl -MCPAN -e shell install Socket::More
For more information on module installation, please visit the detailed CPAN module installation guide.