Socket library for mruby.

mrbgem.rake

+MRuby::Gem::Specification.new('mruby-socket') do |spec|
+  spec.license = 'MIT'
+  spec.authors = 'Internet Initiative Japan'
+end

mrblib/socket.rb

+class Addrinfo
+  def initialize(sockaddr, family=Socket::PF_UNSPEC, socktype=0, protocol=0)
+    @hostname = nil
+    if sockaddr.is_a? Array
+      sary = sockaddr
+      if sary[0] == 'AF_INET' || sary[0] == 'AF_INET6'
+        @sockaddr = Socket.sockaddr_in(sary[1], sary[3])
+        @hostname = sary[2]
+      elsif sary[0] == 'AF_UNIX'
+        @sockaddr = Socket.sockaddr_un(sary[1])
+      end
+    else
+      @sockaddr = sockaddr.dup
+    end
+    if family == Socket::PF_UNSPEC or family == nil
+      @family = Socket._sockaddr_family(@sockaddr)
+    else
+      @family = family
+    end
+    @socktype = socktype
+    @protocol = protocol
+    @canonname = nil
+  end
+
+  def self.foreach(nodename, service, family=nil, socktype=nil, protocol=nil, flags=0, &block)
+    a = self.getaddrinfo(nodename, service, family, socktype, protocol, flags)
+    a.each { |ai| block.call(ai) }
+    a
+  end
+
+  def self.ip(host)
+    Addrinfo.new(Socket.sockaddr_in(0, host))
+  end
+
+  def self.tcp(host, port)
+    Addrinfo.new(Socket.sockaddr_in(port, host), nil, Socket::SOCK_STREAM, Socket::IPPROTO_TCP)
+  end
+
+  def self.udp(host, port)
+    Addrinfo.new(Socket.sockaddr_in(port, host), nil, Socket::SOCK_DGRAM, Socket::IPPROTO_UDP)
+  end
+
+  def self.unix(path, socktype=Socket::SOCK_STREAM)
+    Addrinfo.new(Socket.sockaddr_un(path), Socket::AF_UNIX, socktype)
+  end
+
+  def afamily
+    @family
+  end
+
+  #def bind
+
+  attr_reader :canonname
+
+  #def connect
+  #def connect_from
+  #def connect_to
+
+  #def family_addrinfo(host, port=nil)
+  #def getnameinfo(flags=0)
+  #  Socket.getnameinfo
+  #end
+
+  def inspect
+    if ipv4? or ipv6?
+      if @protocol == Socket::IPPROTO_TCP
+        proto = 'TCP'
+      elsif @protocol == Socket::IPPROTO_UDP
+        proto = 'UDP'
+      else
+        proto = '???'
+      end
+      # how can we get the last part?
+      "#<Addrinfo: #{inspect_sockaddr} #{proto}>"
+    else
+      "#<Addrinfo: #{self.unix_path} SOCK_STREAM>"
+    end
+  end
+
+  def inspect_sockaddr
+    if ipv4?
+      a, p = ip_unpack
+      "#{a}:#{p}"
+    elsif ipv6?
+      a, p = ip_unpack
+      "[#{a}]:#{p}"
+    elsif unix?
+      unix_path
+    else
+      '???'
+    end
+  end
+
+  def ip?
+    ipv4? or ipv6?
+  end
+
+  def ip_address
+    ip_unpack[0]
+  end
+
+  def ip_port
+    ip_unpack[1]
+  end
+
+  def ip_unpack
+    h, p = getnameinfo(Socket::NI_NUMERICHOST|Socket::NI_NUMERICSERV)
+    [ h, p.to_i ]
+  end
+
+  def ipv4?
+    @family == Socket::AF_INET
+  end
+
+  #def ipv4_loopback?
+  #def ipv4_multicast?
+  #def ipv4_private?
+
+  def ipv6?
+    @family == Socket::AF_INET6
+  end
+
+  #def ipv6_loopback?
+  #def ipv6_mc_global?
+  #def ipv6_mc_linklocal?
+  #def ipv6_mc_nodelocal?
+  #def ipv6_mc_orilocal?
+  #def ipv6_mc_sitelocal?
+  #def ipv6_multicast?
+  #def ipv6_to_ipv4
+  #def ipv6_unspecified
+  #def ipv6_v4compat?
+  #def ipv6_v4mapped?
+  #def listen(backlog=5)
+
+  def pfamily
+    @family
+  end
+
+  attr_reader :protocol
+  attr_reader :socktype
+
+  def to_sockaddr 
+    @sockaddr
+  end
+
+  alias to_s to_sockaddr
+
+  def unix?
+    @family == Socket::AF_UNIX
+  end
+end
+
+class BasicSocket
+  @@do_not_reverse_lookup = true
+
+  def self.do_not_reverse_lookup
+    @@do_not_reverse_lookup
+  end
+
+  def self.do_not_reverse_lookup=(val)
+    @@do_not_reverse_lookup = val ? true : false
+  end
+
+  def initialize(*args)
+    super(*args)
+    @do_not_reverse_lookup = @@do_not_reverse_lookup
+  end
+
+  #def connect_address
+
+  def local_address
+    Addrinfo.new self.getsockname
+  end
+
+  def recv_nonblock(maxlen, flags=0)
+    begin
+      _setnonblock(true)
+      recv(maxlen, flags)
+    ensure
+      _setnonblock(false)
+    end
+  end
+
+  def remote_address
+    Addrinfo.new self.getpeername
+  end
+
+  attr_accessor :do_not_reverse_lookup
+end
+
+class IPSocket
+  def self.getddress(host)
+    Addrinfo.ip(host).ip_address
+  end
+
+  def _ai_to_array(ai)
+    case ai.afamily
+    when Socket::AF_INET
+      s = "AF_INET"
+    when Socket::AF_INET6
+      s = "AF_INET6"
+    when Socket::AF_UNIX
+      s = "AF_UNIX"
+    else
+      s = "(unknown AF)"
+    end
+    [ s, ai.ip_port, ai.ip_address, ai.ip_address ]
+  end
+
+  def addr
+    _ai_to_array(Addrinfo.new(self.getsockname))
+  end
+
+  def peeraddr
+    _ai_to_array(Addrinfo.new(self.getpeername))
+  end
+
+  def recvfrom(maxlen, flags=0)
+    msg, sa = _recvfrom(maxlen, flags)
+    [ msg, _ai_to_array(Addrinfo.new(sa)) ]
+  end
+end
+
+class TCPSocket
+  def initialize(host, service, local_host=nil, local_service=nil)
+    self._bless
+    if self.is_a? TCPServer
+      super(host, service)
+    else
+      ai = Addrinfo.getaddrinfo(host, service)[0]
+      super(Socket._socket(ai.afamily, Socket::SOCK_STREAM, 0), "r+")
+      # XXX: bind(2)
+      Socket._connect(self.fileno, ai.to_sockaddr)
+      self
+    end
+  end
+
+  #def self.gethostbyname(host)
+end
+
+class TCPServer
+  def initialize(host=nil, service)
+    self._bless
+    ai = Addrinfo.getaddrinfo(host, service, nil, nil, nil, Socket::AI_PASSIVE)[0]
+    super(Socket._socket(ai.afamily, Socket::SOCK_STREAM, 0), "r+")
+    Socket._bind(self.fileno, ai.to_sockaddr)
+    listen(5)
+    self
+  end
+
+  def accept
+    TCPSocket.for_fd(self.sysaccept)
+  end
+
+  def accept_nonblock
+    begin
+      self._setnonblock(true)
+      self.accept
+    ensure
+      self._setnonblock(false)
+    end
+  end
+
+  def listen(backlog)
+    Socket._listen(self.fileno, backlog)
+    0
+  end
+
+  def sysaccept
+    Socket._accept(self.fileno)[0]
+  end
+end
+
+class UDPSocket
+  def initialize(af=Socket::AF_INET)
+    self._bless
+    super(Socket._socket(af, Socket::SOCK_DGRAM, 0), "r+")
+    self
+  end
+
+  def bind(host, port)
+    Socket._bind(self.fileno, Socket.sockaddr_in(port, host))
+    0
+  end
+
+  def connect(host, port)
+    Socket._connect(self.fileno, Socket.sockaddr_in(port, host))
+    0
+  end
+
+  def recvfrom_nonblock(*args)
+    s = self
+    begin
+      self._setnonblock(true)
+      self.recvfrom(*args)
+    ensure
+      # XXX: self is a SystemcallException here! (should be bug)
+      s._setnonblock(false)
+    end
+  end
+
+  def send(mesg, flags, host=nil, port=nil)
+    if port
+      super(mesg, flags, Socket.sockaddr_in(port, host))
+    elsif host
+      super(mesg, flags, host)
+    else
+      super(mesg, flags)
+    end
+  end
+end
+
+class Socket
+  def initialize(domain, type, protocol=0)
+    self._bless
+    super(Socket._socket(domain, type, protocol), "r+")
+  end
+
+  #def self.accept_loop
+
+  # def self.getaddrinfo
+    # by Addrinfo.getaddrinfo
+  #end
+
+  #def self.getnameinfo
+  #def self.ip_address_list
+
+  def self.open(*args)
+    new(args)
+  end
+
+  def self.sockaddr_in(port, host)
+    ai = Addrinfo.getaddrinfo(host, port)[0]
+    ai.to_sockaddr
+  end
+
+  #def self.tcp
+  #def self.tcp_server_loop
+  #def self.tcp_server_sockets
+  #def self.udp_server_loop
+  #def self.udp_server_loop_on
+  #def self.udp_server_recv
+  #def self.udp_server_sockets
+  #def self.unix(path)
+  #def self.unix_server_loop
+  #def self.unix_server_socket
+
+  def self.unpack_sockaddr_in(sa)
+    Addrinfo.new(sa).ip_unpack.reverse
+  end
+
+  def self.unpack_sockaddr_un(sa)
+    Addrinfo.new(sa).unix_path
+  end
+
+  class << self
+    alias pack_sockaddr_in sockaddr_in
+    alias pack_sockaddr_un sockaddr_un
+    alias pair socketpair
+  end
+
+  def accept
+    fd, addr = self.sysaccept
+    [ Socket.for_fd(fd), addr ]
+  end
+
+  def accept_nonblock
+    begin
+      self._setnonblock(true)
+      self.accept
+    ensure
+      self._setnonblock(false)
+    end
+  end
+
+  def bind(sockaddr)
+    sockaddr = sockaddr.to_sockaddr if sockaddr.is_a? Addrinfo
+    Socket._bind(self.fileno, sockaddr)
+    0
+  end
+
+  def connect(sockaddr)
+    sockaddr = sockaddr.to_sockaddr if sockaddr.is_a? Addrinfo
+    Socket._bind(self.fileno, sockaddr)
+    0
+  end
+
+  def connect_nonblock(sockaddr)
+    begin
+      self._setnonblock(true)
+      self.connect(sockaddr)
+    ensure
+      self._setnonblock(false)
+    end
+  end
+
+  #def ipv6only!
+
+  def listen(backlog)
+    Socket._listen(self.fileno, backlog)
+    0
+  end
+
+  def recvfrom(maxlen, flags=0)
+    msg, sa = _recvfrom(maxlen, flags)
+    [ msg, _ai_to_array(Addrinfo.new(sa)) ]
+  end
+
+  def recvfrom_nonblock(*args)
+    begin
+      self._setnonblock(true)
+      self._recvfrom(*args)
+    ensure
+      self._setnonblock(false)
+    end
+  end
+
+  def sysaccept
+    Socket._accept(self.fileno)[0]
+  end
+end
+
+class UNIXSocket
+  def initialize(path, &block)
+    self._bless
+    super(Socket._socket(AF_UNIX, SOCK_STREAM, 0), "r+")
+    Socket._connect(self.fileno, Socket.sockaddr_un(path))
+    if block
+      block.call(self)
+    else
+      self
+    end
+  end
+
+  def self.socketpair(type=Socket::SOCK_STREAM, protocol=0)
+    a = Socket.socketpair(Socket::AF_UNIX, type, protocol)
+    [ UNIXSocket.for_fd(a[0]), UNIXSocket.for_fd(a[1]) ]
+  end
+
+  class << self
+    alias pair socketpair
+  end
+
+  def addr
+    [ "AF_UNIX", path ]
+  end
+
+  def path
+    Addrinfo.new(self.getsockname).unix_path
+  end
+
+  def peeraddr
+    [ "AF_UNIX", Addrinfo.new(self.getpeername).unix_path ]
+  end
+
+  #def recv_io
+
+  def recvfrom(maxlen, flags=0)
+    msg, sa = _recvfrom(maxlen, flags)
+    [ msg, [ "AF_UNIX", Addrinfo.new(sa).unix_path ] ]
+  end
+
+  #def send_io
+end
+
+class UNIXServer
+  def initialize(path, &block)
+    self._bless
+    super(Socket._socket(Socket::AF_UNIX, Socket::SOCK_STREAM, 0), "r")
+    Socket._bind(self.fileno, Socket.pack_sockaddr_un(path))
+    listen(5)
+    self
+  end
+
+  def accept
+    fd, addr = self.sysaccept
+    [ UNIXSocket.for_fd(fd), addr ]
+  end
+
+  def accept_nonblock
+    begin
+      self._setnonblock(true)
+      self.accept
+    ensure
+      self._setnonblock(false)
+    end
+  end
+
+  def listen(backlog)
+    Socket._listen(self.fileno, backlog)
+    0
+  end
+
+  def sysaccept
+    Socket._accept(self.fileno)[0]
+  end
+end
+
+class Socket
+  include Constants
+end
+
+class Socket
+  class Option
+    def initialize(family, level, optname, data)
+      @family  = family
+      @level   = level
+      @optname = optname
+      @data    = data
+    end
+
+    def self.bool(family, level, optname, bool)
+      self.new(family, level, optname, [(bool ? 1 : 0)].pack('i'))
+    end
+
+    def self.int(family, level, optname, integer)
+      self.new(family, level, optname, [integer].pack('i'))
+    end
+
+    #def self.linger(family, level, optname, integer)
+    #end
+
+    attr_reader :data, :family, :level, :optname
+
+    def bool
+      @data.unpack('i')[0] != 0
+    end
+
+    def inspect
+      # notyet
+    end
+
+    def int
+      @data.unpack('i')[0]
+    end
+
+    def linger
+      raise NotImplementedError.new
+    end
+
+    def unpack(template)
+      raise NotImplementedError.new
+    end
+  end
+end
+
+class SocketError < StandardError; end

src/const.cstub

+#ifdef AF_INET
+  define_const(AF_INET);
+#endif
+#ifdef PF_INET
+  define_const(PF_INET);
+#endif
+#ifdef AF_INET6
+  define_const(AF_INET6);
+#endif
+#ifdef PF_INET6
+  define_const(PF_INET6);
+#endif
+#ifdef AF_LINK
+  define_const(AF_LINK);
+#endif
+#ifdef PF_LINK
+  define_const(PF_LINK);
+#endif
+#ifdef AF_LOCAL
+  define_const(AF_LOCAL);
+#endif
+#ifdef PF_LOCAL
+  define_const(PF_LOCAL);
+#endif
+#ifdef AF_UNIX
+  define_const(AF_UNIX);
+#endif
+#ifdef PF_UNIX
+  define_const(PF_UNIX);
+#endif
+#ifdef AF_MAX
+  define_const(AF_MAX);
+#endif
+#ifdef AF_UNSPEC
+  define_const(AF_UNSPEC);
+#endif
+#ifdef PF_UNSPEC
+  define_const(PF_UNSPEC);
+#endif
+#ifdef AF_ROUTE
+  define_const(AF_ROUTE);
+#endif
+#ifdef PF_ROUTE
+  define_const(PF_ROUTE);
+#endif
+#ifdef AI_CANONNAME
+  define_const(AI_CANONNAME);
+#endif
+#ifdef AI_FQDN
+  define_const(AI_FQDN);
+#endif
+#ifdef AI_NUMERICHOST
+  define_const(AI_NUMERICHOST);
+#endif
+#ifdef AI_NUMERICSERV
+  define_const(AI_NUMERICSERV);
+#endif
+#ifdef AI_PASSIVE
+  define_const(AI_PASSIVE);
+#endif
+#ifdef IPPROTO_ICMP
+  define_const(IPPROTO_ICMP);
+#endif
+#ifdef IPPROTO_IP
+  define_const(IPPROTO_IP);
+#endif
+#ifdef IPPROTO_IPV6
+  define_const(IPPROTO_IPV6);
+#endif
+#ifdef IPPROTO_RAW
+  define_const(IPPROTO_RAW);
+#endif
+#ifdef IPPROTO_TCP
+  define_const(IPPROTO_TCP);
+#endif
+#ifdef IPPROTO_UDP
+  define_const(IPPROTO_UDP);
+#endif
+#ifdef MSG_BCAST
+  define_const(MSG_BCAST);
+#endif
+#ifdef MSG_CTRUNC
+  define_const(MSG_CTRUNC);
+#endif
+#ifdef MSG_DONTROUTE
+  define_const(MSG_DONTROUTE);
+#endif
+#ifdef MSG_DONTWAIT
+  define_const(MSG_DONTWAIT);
+#endif
+#ifdef MSG_EOR
+  define_const(MSG_EOR);
+#endif
+#ifdef MSG_MCAST
+  define_const(MSG_MCAST);
+#endif
+#ifdef MSG_NOSIGNAL
+  define_const(MSG_NOSIGNAL);
+#endif
+#ifdef MSG_OOB
+  define_const(MSG_OOB);
+#endif
+#ifdef MSG_PEEK
+  define_const(MSG_PEEK);
+#endif
+#ifdef MSG_TRUNC
+  define_const(MSG_TRUNC);
+#endif
+#ifdef MSG_WAITALL
+  define_const(MSG_WAITALL);
+#endif
+#ifdef NI_DGRAM
+  define_const(NI_DGRAM);
+#endif
+#ifdef NI_MAXHOST
+  define_const(NI_MAXHOST);
+#endif
+#ifdef NI_MAXSERV
+  define_const(NI_MAXSERV);
+#endif
+#ifdef NI_NAMEREQD
+  define_const(NI_NAMEREQD);
+#endif
+#ifdef NI_NOFQDN
+  define_const(NI_NOFQDN);
+#endif
+#ifdef NI_NUMERICHOST
+  define_const(NI_NUMERICHOST);
+#endif
+#ifdef NI_NUMERICSERV
+  define_const(NI_NUMERICSERV);
+#endif
+#ifdef SHUT_RD
+  define_const(SHUT_RD);
+#endif
+#ifdef SHUT_WR
+  define_const(SHUT_WR);
+#endif
+#ifdef SHUT_RDWR
+  define_const(SHUT_RDWR);
+#endif
+#ifdef SO_BINDANY
+  define_const(SO_BINDANY);
+#endif
+#ifdef SO_BROADCAST
+  define_const(SO_BROADCAST);
+#endif
+#ifdef SO_DEBUG
+  define_const(SO_DEBUG);
+#endif
+#ifdef SO_DONTROUTE
+  define_const(SO_DONTROUTE);
+#endif
+#ifdef SO_ERROR
+  define_const(SO_ERROR);
+#endif
+#ifdef SO_KEEPALIVE
+  define_const(SO_KEEPALIVE);
+#endif
+#ifdef SO_LINGER
+  define_const(SO_LINGER);
+#endif
+#ifdef SO_OOBINLINE
+  define_const(SO_OOBINLINE);
+#endif
+#ifdef SO_PEERCRED
+  define_const(SO_PEERCRED);
+#endif
+#ifdef SO_RCVBUF
+  define_const(SO_RCVBUF);
+#endif
+#ifdef SO_RCVLOWAT
+  define_const(SO_RCVLOWAT);
+#endif
+#ifdef SO_RCVTIMEO
+  define_const(SO_RCVTIMEO);
+#endif
+#ifdef SO_REUSEADDR
+  define_const(SO_REUSEADDR);
+#endif
+#ifdef SO_REUSEPORT
+  define_const(SO_REUSEPORT);
+#endif
+#ifdef SO_RTABLE
+  define_const(SO_RTABLE);
+#endif
+#ifdef SO_SNDBUF
+  define_const(SO_SNDBUF);
+#endif
+#ifdef SO_SNDLOWAT
+  define_const(SO_SNDLOWAT);
+#endif
+#ifdef SO_SNDTIMEO
+  define_const(SO_SNDTIMEO);
+#endif
+#ifdef SO_SPLICE
+  define_const(SO_SPLICE);
+#endif
+#ifdef SO_TIMESTAMP
+  define_const(SO_TIMESTAMP);
+#endif
+#ifdef SO_TYPE
+  define_const(SO_TYPE);
+#endif
+#ifdef SOCK_DGRAM
+  define_const(SOCK_DGRAM);
+#endif
+#ifdef SOCK_RAW
+  define_const(SOCK_RAW);
+#endif
+#ifdef SOCK_SEQPACKET
+  define_const(SOCK_SEQPACKET);
+#endif
+#ifdef SOCK_STREAM
+  define_const(SOCK_STREAM);
+#endif
+#ifdef SOL_SOCKET
+  define_const(SOL_SOCKET);
+#endif

src/const.def

+AF_INET
+PF_INET
+AF_INET6
+PF_INET6
+AF_LINK
+PF_LINK
+AF_LOCAL
+PF_LOCAL
+AF_UNIX
+PF_UNIX
+AF_MAX
+AF_UNSPEC
+PF_UNSPEC
+AF_ROUTE
+PF_ROUTE
+
+AI_CANONNAME
+AI_FQDN
+AI_NUMERICHOST
+AI_NUMERICSERV
+AI_PASSIVE
+
+IPPROTO_ICMP
+IPPROTO_IP
+IPPROTO_IPV6
+IPPROTO_RAW
+IPPROTO_TCP
+IPPROTO_UDP
+
+MSG_BCAST
+MSG_CTRUNC
+MSG_DONTROUTE
+MSG_DONTWAIT
+MSG_EOR
+MSG_MCAST
+MSG_NOSIGNAL
+MSG_OOB
+MSG_PEEK
+MSG_TRUNC
+MSG_WAITALL
+
+NI_DGRAM
+NI_MAXHOST
+NI_MAXSERV
+NI_NAMEREQD
+NI_NOFQDN
+NI_NUMERICHOST
+NI_NUMERICSERV
+
+SHUT_RD
+SHUT_WR
+SHUT_RDWR
+
+SO_BINDANY
+SO_BROADCAST
+SO_DEBUG
+SO_DONTROUTE
+SO_ERROR
+SO_KEEPALIVE
+SO_LINGER
+SO_OOBINLINE
+SO_PEERCRED
+SO_RCVBUF
+SO_RCVLOWAT
+SO_RCVTIMEO
+SO_REUSEADDR
+SO_REUSEPORT
+SO_RTABLE
+SO_SNDBUF
+SO_SNDLOWAT
+SO_SNDTIMEO
+SO_SPLICE
+SO_TIMESTAMP
+SO_TYPE
+
+SOCK_DGRAM
+SOCK_RAW
+SOCK_SEQPACKET
+SOCK_STREAM
+
+SOL_SOCKET

src/gen.rb

+#!/usr/bin/env ruby
+
+Dir.chdir(File.dirname($0))
+
+f = File.open("const.cstub", "w")
+
+IO.readlines("const.def").each { |name|
+  name.sub(/^#.*/, "")
+  name.strip!
+  next if name.empty?
+
+  f.write <<CODE
+#ifdef #{name}
+  define_const(#{name});
+#endif
+CODE
+}

src/socket.c

+/*
+** socket.c - Socket module
+**
+** See Copyright Notice in mruby.h
+*/
+
+#include "mruby.h"
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <stddef.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "mruby/array.h"
+#include "mruby/class.h"
+#include "mruby/data.h"
+#include "mruby/string.h"
+#include "mruby/variable.h"
+#include "mruby/ext/io.h"
+
+#define E_SOCKET_ERROR             (mrb_class_get(mrb, "SocketError"))
+
+
+static mrb_value
+mrb_addrinfo_getaddrinfo(mrb_state *mrb, mrb_value klass)
+{
+  struct addrinfo hints, *res0, *res;
+  struct sockaddr_un sun;
+  mrb_value ai, ary, family, lastai, nodename, protocol, s, sa, service, socktype;
+  mrb_int flags;
+  int arena_idx, error;
+  const char *hostname = NULL, *servname = NULL;
+
+  ary = mrb_ary_new(mrb);
+  arena_idx = mrb_gc_arena_save(mrb);  /* ary must be on arena! */
+
+  s = mrb_str_new(mrb, (void *)&sun, sizeof(sun));
+
+  family = socktype = protocol = mrb_nil_value();
+  flags = 0;
+  mrb_get_args(mrb, "oo|oooi", &nodename, &service, &family, &socktype, &protocol, &flags);
+
+  if (mrb_string_p(nodename)) {
+    hostname = mrb_str_to_cstr(mrb, nodename);
+  } else if (mrb_nil_p(nodename)) {
+    hostname = NULL;
+  } else {
+    mrb_raise(mrb, E_TYPE_ERROR, "nodename must be String or nil");
+  }
+
+  if (mrb_string_p(service)) {
+    servname = mrb_str_to_cstr(mrb, service);
+  } else if (mrb_fixnum_p(service)) {
+    servname = mrb_str_to_cstr(mrb, mrb_funcall(mrb, service, "to_s", 0));
+  } else if (mrb_nil_p(nodename)) {
+    servname = NULL;
+  } else {
+    mrb_raise(mrb, E_TYPE_ERROR, "service must be String, Fixnum, or nil");
+  }
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_flags = flags;
+
+  if (mrb_fixnum_p(family)) {
+    hints.ai_family = mrb_fixnum(family);
+  }
+
+  if (mrb_fixnum_p(socktype)) {
+    hints.ai_socktype = mrb_fixnum(socktype);
+  }
+
+  lastai = mrb_cv_get(mrb, klass, mrb_intern_cstr(mrb, "_lastai"));
+  if (mrb_voidp_p(ai)) {
+    freeaddrinfo(mrb_voidp(ai));
+    mrb_cv_set(mrb, klass, mrb_intern_cstr(mrb, "_lastai"), mrb_nil_value());
+  }
+
+  error = getaddrinfo(hostname, servname, &hints, &res0);
+  if (error) {
+    mrb_raisef(mrb, E_SOCKET_ERROR, "getaddrinfo: %S", mrb_str_new_cstr(mrb, gai_strerror(error)));
+  }
+  mrb_cv_set(mrb, klass, mrb_intern_cstr(mrb, "_lastai"), mrb_voidp_value(res0));
+
+  for (res = res0; res != NULL; res = res->ai_next) {
+    sa = mrb_str_new(mrb, (void *)res->ai_addr, res->ai_addrlen);
+    ai = mrb_funcall(mrb, klass, "new", 4, sa, mrb_fixnum_value(res->ai_family), mrb_fixnum_value(res->ai_socktype), mrb_fixnum_value(res->ai_protocol));
+    mrb_ary_push(mrb, ary, ai);
+    mrb_gc_arena_restore(mrb, arena_idx);
+  }
+
+  freeaddrinfo(res0);
+  mrb_cv_set(mrb, klass, mrb_intern_cstr(mrb, "_lastai"), mrb_nil_value());
+
+  return ary;
+}
+
+static mrb_value
+mrb_addrinfo_getnameinfo(mrb_state *mrb, mrb_value self)
+{
+  mrb_int flags;
+  mrb_value ary, host, sastr, serv;
+  int error;
+
+  flags = 0;
+  mrb_get_args(mrb, "|i", &flags);
+  host = mrb_str_buf_new(mrb, NI_MAXHOST);
+  serv = mrb_str_buf_new(mrb, NI_MAXSERV);
+
+  sastr = mrb_iv_get(mrb, self, mrb_intern(mrb, "@sockaddr"));
+  if (!mrb_string_p(sastr)) {
+    mrb_raise(mrb, E_SOCKET_ERROR, "invalid sockaddr");
+  }
+  error = getnameinfo((struct sockaddr *)RSTRING_PTR(sastr), (socklen_t)RSTRING_LEN(sastr), RSTRING_PTR(host), NI_MAXHOST, RSTRING_PTR(serv), NI_MAXSERV, flags);
+  if (error != 0) {
+    mrb_raisef(mrb, E_SOCKET_ERROR, "getnameinfo: %s", gai_strerror(error));
+  }
+  ary = mrb_ary_new_capa(mrb, 2);
+  mrb_str_resize(mrb, host, strlen(RSTRING_PTR(host)));
+  mrb_ary_push(mrb, ary, host);
+  mrb_str_resize(mrb, serv, strlen(RSTRING_PTR(serv)));
+  mrb_ary_push(mrb, ary, serv);
+  return ary;
+}
+
+static mrb_value
+mrb_addrinfo_unix_path(mrb_state *mrb, mrb_value self)
+{
+  mrb_value sastr;
+
+  sastr = mrb_iv_get(mrb, self, mrb_intern(mrb, "@sockaddr"));
+  if (((struct sockaddr *)RSTRING_PTR(sastr))->sa_family != AF_UNIX)
+    mrb_raise(mrb, E_SOCKET_ERROR, "need AF_UNIX address");
+  return mrb_str_new_cstr(mrb, ((struct sockaddr_un *)RSTRING_PTR(sastr))->sun_path);
+}
+
+static mrb_value
+sa2addrlist(mrb_state *mrb, const struct sockaddr *sa, socklen_t salen)
+{
+  mrb_value ary, host;
+  unsigned short port;
+  const char *afstr;
+
+  switch (sa->sa_family) {
+  case AF_INET:
+    afstr = "AF_INET";
+    port = ((struct sockaddr_in *)sa)->sin_port;
+    break;
+  case AF_INET6:
+    afstr = "AF_INET6";
+    port = ((struct sockaddr_in6 *)sa)->sin6_port;
+    break;
+  default:
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "bad af");
+    return mrb_nil_value();
+  }
+  port = ntohs(port);
+  host = mrb_str_buf_new(mrb, NI_MAXHOST);
+  if (getnameinfo(sa, salen, RSTRING_PTR(host), NI_MAXHOST, NULL, 0, NI_NUMERICHOST) == -1)
+    mrb_sys_fail(mrb, "getnameinfo");
+  mrb_str_resize(mrb, host, strlen(RSTRING_PTR(host)));
+  ary = mrb_ary_new_capa(mrb, 4);
+  mrb_ary_push(mrb, ary, mrb_str_new_cstr(mrb, afstr));
+  mrb_ary_push(mrb, ary, mrb_fixnum_value(port));
+  mrb_ary_push(mrb, ary, host);
+  mrb_ary_push(mrb, ary, host);
+  return ary;
+}
+
+static int
+socket_fd(mrb_state *mrb, mrb_value sock)
+{
+  return mrb_fixnum(mrb_funcall(mrb, sock, "fileno", 0));
+}
+
+static int
+socket_family(int s)
+{
+  struct sockaddr_storage ss;
+  socklen_t salen;
+
+  salen = sizeof(ss);
+  if (getsockname(s, (struct sockaddr *)&ss, &salen) == -1)
+    return AF_UNSPEC;
+  return ss.ss_family;
+}
+
+static mrb_value
+mrb_basicsocket_getpeereid(mrb_state *mrb, mrb_value self)
+{ 
+  mrb_value ary;
+  gid_t egid;
+  uid_t euid;
+  int s;
+  
+  s = socket_fd(mrb, self);
+  if (getpeereid(s, &euid, &egid) != 0)
+    mrb_sys_fail(mrb, "getpeereid");
+
+  ary = mrb_ary_new_capa(mrb, 2);
+  mrb_ary_push(mrb, ary, mrb_fixnum_value((mrb_int)euid));
+  mrb_ary_push(mrb, ary, mrb_fixnum_value((mrb_int)egid));
+  return ary;
+}
+
+static mrb_value
+mrb_basicsocket_getpeername(mrb_state *mrb, mrb_value self)
+{ 
+  struct sockaddr_storage ss;
+  socklen_t salen;
+  
+  salen = sizeof(ss);
+  if (getpeername(socket_fd(mrb, self), (struct sockaddr *)&ss, &salen) != 0)
+    mrb_sys_fail(mrb, "getpeername");
+
+  return mrb_str_new(mrb, (void *)&ss, salen);
+}
+
+static mrb_value
+mrb_basicsocket_getsockname(mrb_state *mrb, mrb_value self)
+{ 
+  struct sockaddr_storage ss;
+  socklen_t salen;
+  
+  salen = sizeof(ss);
+  if (getsockname(socket_fd(mrb, self), (struct sockaddr *)&ss, &salen) != 0)
+    mrb_sys_fail(mrb, "getsockname");
+
+  return mrb_str_new(mrb, (void *)&ss, salen);
+}
+
+static mrb_value
+mrb_basicsocket_getsockopt(mrb_state *mrb, mrb_value self)
+{ 
+  int opt, s;
+  mrb_int family, level, optname;
+  mrb_value c, data;
+  socklen_t optlen;
+
+  mrb_get_args(mrb, "ii", &level, &optname);
+  s = socket_fd(mrb, self);
+  optlen = sizeof(opt);
+  if (getsockopt(s, level, optname, &opt, &optlen) == -1)
+    mrb_sys_fail(mrb, "getsockopt");
+  c = mrb_const_get(mrb, mrb_obj_value(mrb_class_get(mrb, "Socket")), mrb_intern(mrb, "Option"));
+  family = socket_family(s);
+  data = mrb_str_new(mrb, (char *)&opt, sizeof(int));
+  return mrb_funcall(mrb, c, "new", 4, mrb_fixnum_value(family), mrb_fixnum_value(level), mrb_fixnum_value(optname), data);
+}
+
+static mrb_value
+mrb_basicsocket_recv(mrb_state *mrb, mrb_value self)
+{ 
+  int n;
+  mrb_int maxlen, flags = 0;
+  mrb_value buf;
+
+  mrb_get_args(mrb, "i|i", &maxlen, &flags);
+  buf = mrb_str_buf_new(mrb, maxlen);
+  n = recv(socket_fd(mrb, self), RSTRING_PTR(buf), maxlen, flags);
+  if (n == -1)
+    mrb_sys_fail(mrb, "recv");
+  mrb_str_resize(mrb, buf, n);
+  return buf;
+}
+
+static mrb_value
+mrb_basicsocket_recvfrom(mrb_state *mrb, mrb_value self)
+{ 
+  int n;
+  mrb_int maxlen, flags = 0;
+  mrb_value ary, buf, sa;
+  socklen_t socklen;
+
+  mrb_get_args(mrb, "i|i", &maxlen, &flags);
+  buf = mrb_str_buf_new(mrb, maxlen);
+  socklen = sizeof(struct sockaddr_storage);
+  sa = mrb_str_buf_new(mrb, socklen);
+  n = recvfrom(socket_fd(mrb, self), RSTRING_PTR(buf), maxlen, flags, (struct sockaddr *)RSTRING_PTR(sa), &socklen);
+  if (n == -1)
+    mrb_sys_fail(mrb, "recvfrom");
+  mrb_str_resize(mrb, buf, n);
+  mrb_str_resize(mrb, sa, socklen);
+  ary = mrb_ary_new_capa(mrb, 2);
+  mrb_ary_push(mrb, ary, buf);
+  mrb_ary_push(mrb, ary, sa);
+  return ary;
+}
+
+static mrb_value
+mrb_basicsocket_send(mrb_state *mrb, mrb_value self)
+{ 
+  int n;
+  mrb_int flags;
+  mrb_value dest, mesg;
+
+  dest = mrb_nil_value();
+  mrb_get_args(mrb, "Si|S", &mesg, &flags, &dest);
+  if (mrb_nil_p(dest)) {
+    n = send(socket_fd(mrb, self), RSTRING_PTR(mesg), RSTRING_LEN(mesg), flags);
+  } else {
+    // XXX: length check
+    n = sendto(socket_fd(mrb, self), RSTRING_PTR(mesg), RSTRING_LEN(mesg), flags, (const void *)RSTRING_PTR(dest), RSTRING_LEN(dest));
+  }
+  if (n == -1)
+    mrb_sys_fail(mrb, "send");
+  return mrb_fixnum_value(n);
+}
+
+static mrb_value
+mrb_basicsocket_setnonblock(mrb_state *mrb, mrb_value self)
+{ 
+  int fd, flags;
+  mrb_value bool;
+
+  mrb_get_args(mrb, "o", &bool);
+  fd = socket_fd(mrb, self);
+
+  flags = fcntl(fd, F_GETFL, 0);
+  if (flags == 1)
+    mrb_sys_fail(mrb, "fcntl");
+  if (mrb_test(bool))
+    flags |= O_NONBLOCK;
+  else
+    flags &= ~O_NONBLOCK;
+  if (fcntl(fd, F_SETFL, flags) == -1)
+    mrb_sys_fail(mrb, "fcntl");
+  return mrb_nil_value();
+}
+
+static mrb_value
+mrb_basicsocket_setsockopt(mrb_state *mrb, mrb_value self)
+{ 
+  int argc, s;
+  mrb_int level = 0, optname;
+  mrb_value optval, so;
+
+  argc = mrb_get_args(mrb, "o|io", &so, &optname, &optval);
+  if (argc == 3) {
+    if (!mrb_fixnum_p(so)) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "level is not an integer");
+    }
+    level = mrb_fixnum(so);
+    if (mrb_string_p(optval)) {
+      /* that's good */
+    } else if (mrb_type(optval) == MRB_TT_TRUE || mrb_type(optval) == MRB_TT_FALSE) {
+      mrb_int i = mrb_test(optval) ? 1 : 0;
+      optval = mrb_str_new(mrb, (char *)&i, sizeof(i));
+    } else if (mrb_fixnum_p(optval)) {
+      mrb_int i = mrb_fixnum(optval);
+      optval = mrb_str_new(mrb, (char *)&i, sizeof(i));
+    } else {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "optval should be true, false, an integer, or a string");
+    }
+  } else if (argc == 1) {
+    if (strcmp(mrb_obj_classname(mrb, so), "Socket::Option") != 0)
+      mrb_raisef(mrb, E_ARGUMENT_ERROR, "not an instance of Socket::Option");
+    level = mrb_fixnum(mrb_funcall(mrb, so, "level", 0));
+    optname = mrb_fixnum(mrb_funcall(mrb, so, "optname", 0));
+    optval = mrb_funcall(mrb, so, "data", 0);
+  } else {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%d for 3)", argc);
+  }
+
+  s = socket_fd(mrb, self);
+  if (setsockopt(s, level, optname, RSTRING_PTR(optval), RSTRING_LEN(optval)) == -1)
+    mrb_sys_fail(mrb, "setsockopt");
+  return mrb_fixnum_value(0);
+}
+
+static mrb_value
+mrb_basicsocket_shutdown(mrb_state *mrb, mrb_value self)
+{ 
+  mrb_int how = SHUT_RDWR;
+
+  mrb_get_args(mrb, "|i", &how);
+  if (shutdown(socket_fd(mrb, self), how) != 0)
+    mrb_sys_fail(mrb, "shutdown");
+  return mrb_fixnum_value(0);
+}
+
+static mrb_value
+mrb_ipsocket_ntop(mrb_state *mrb, mrb_value klass)
+{ 
+  mrb_int af, n;
+  char *addr, buf[50];
+
+  mrb_get_args(mrb, "is", &af, &addr, &n);
+  if ((af == AF_INET && n != 4) || (af == AF_INET6 && n != 16))
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "invalid address");
+  if (inet_ntop(af, addr, buf, sizeof(buf)) == NULL)
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "invalid address");
+  return mrb_str_new_cstr(mrb, buf);
+}
+
+static mrb_value
+mrb_ipsocket_pton(mrb_state *mrb, mrb_value klass)
+{ 
+  mrb_int af, n;
+  char *bp, buf[50];
+
+  mrb_get_args(mrb, "is", &af, &bp, &n);
+  if (n > sizeof(buf) - 1)
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "invalid address");
+  memcpy(buf, bp, n);
+  buf[n] = '\0';
+
+  if (af == AF_INET) {
+    struct in_addr in;
+    if (inet_pton(AF_INET, buf, (void *)&in.s_addr) != 1)
+      goto invalid;
+    return mrb_str_new(mrb, (char *)&in.s_addr, 4);
+  } else if (af == AF_INET6) {
+    struct in6_addr in6;
+    if (inet_pton(AF_INET6, buf, (void *)&in6.s6_addr) != 1)
+      goto invalid;
+    return mrb_str_new(mrb, (char *)&in6.s6_addr, 16);
+  } else
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "unsupported address family");
+
+invalid:
+  mrb_raise(mrb, E_ARGUMENT_ERROR, "invalid address");
+  return mrb_nil_value(); /* dummy */
+}
+
+static mrb_value
+mrb_ipsocket_recvfrom(mrb_state *mrb, mrb_value self)
+{ 
+  struct sockaddr_storage ss;
+  socklen_t socklen;
+  mrb_value a, buf, pair;
+  mrb_int flags, maxlen, n;
+  int fd;
+
+  fd = socket_fd(mrb, self);
+  flags = 0;
+  mrb_get_args(mrb, "i|i", &maxlen, &flags);
+  buf = mrb_str_buf_new(mrb, maxlen);
+  socklen = sizeof(ss);
+  n = recvfrom(fd, RSTRING_PTR(buf), maxlen, flags,
+  	       (struct sockaddr *)&ss, &socklen);
+  if (n == -1) {
+    mrb_sys_fail(mrb, "recvfrom");
+  }
+  mrb_str_resize(mrb, buf, n);
+  a = sa2addrlist(mrb, (struct sockaddr *)&ss, socklen);
+  pair = mrb_ary_new_capa(mrb, 2);
+  mrb_ary_push(mrb, pair, buf);
+  mrb_ary_push(mrb, pair, a);
+  return pair;
+}
+
+static mrb_value
+mrb_udpsocket_bind(mrb_state *mrb, mrb_value self)
+{ 
+  struct addrinfo hints, *res;
+  mrb_int n, port;
+  int error, s;
+  char *host, hostbuf[256], portbuf[6];
+
+  s = socket_fd(mrb, self);
+  mrb_get_args(mrb, "si", &host, &n, &port);
+  if (n > sizeof(hostbuf) - 1) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "host is too long");
+  }
+  memcpy(hostbuf, host, n);
+  hostbuf[n] = '\0';
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_socktype = SOCK_DGRAM;
+  hints.ai_flags = AI_NUMERICSERV|AI_PASSIVE;
+  snprintf(portbuf, sizeof(portbuf), "%d", port);
+  error = getaddrinfo(hostbuf, portbuf, &hints, &res);
+  if (error != 0)
+    mrb_raise(mrb, E_RUNTIME_ERROR, "getaddrinfo(2) failed");
+  if (bind(s, res->ai_addr, res->ai_addrlen) == -1) {
+    freeaddrinfo(res);
+    mrb_raise(mrb, E_RUNTIME_ERROR, "bind(2) failed");
+  }
+  freeaddrinfo(res);
+  return mrb_fixnum_value(0);
+}
+
+static mrb_value
+mrb_udpsocket_connect(mrb_state *mrb, mrb_value self)
+{ 
+  struct addrinfo hints, *res;
+  mrb_int n, port;
+  int error, s;
+  char *host, hostbuf[256], portbuf[6];
+
+  mrb_get_args(mrb, "si", &host, &n, &port);
+  s = socket_fd(mrb, self);
+
+  if (n > sizeof(hostbuf) - 1) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "host is too long");
+  }
+  memcpy(hostbuf, host, n);
+  hostbuf[n] = '\0';
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_socktype = SOCK_DGRAM;
+  hints.ai_flags = AI_NUMERICSERV;
+  snprintf(portbuf, sizeof(portbuf), "%d", port);
+  error = getaddrinfo(hostbuf, portbuf, &hints, &res);
+  if (error != 0)
+    mrb_raise(mrb, E_RUNTIME_ERROR, "getaddrinfo(2) failed");
+  if (connect(s, res->ai_addr, res->ai_addrlen) == -1) {
+    freeaddrinfo(res);
+    mrb_raise(mrb, E_RUNTIME_ERROR, "connect(2) failed");
+  }
+  freeaddrinfo(res);
+  return mrb_fixnum_value(0);
+}
+
+static mrb_value
+mrb_udpsocket_send(mrb_state *mrb, mrb_value self)
+{ 
+  struct addrinfo hints, *res;
+  mrb_int n, flags;
+  mrb_value host, port;
+  int argc, hlen, s;
+  char hostbuf[256], *msg, portbuf[6];
+
+  argc = mrb_get_args(mrb, "si|oo", &msg, &hlen, &flags, &host, &port);
+  s = socket_fd(mrb, self);
+  n = -1;
+  if (argc == 2) {
+    n = send(s, msg, hlen, flags);
+  } else if (argc == 4) {
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_socktype = SOCK_DGRAM;
+    hints.ai_protocol = IPPROTO_UDP;
+    hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
+    memcpy(hostbuf, RSTRING_PTR(host), RSTRING_LEN(host));
+    hostbuf[RSTRING_LEN(host)] = '\0';
+    snprintf(portbuf, sizeof(portbuf), "%u", mrb_fixnum(port));
+    if (getaddrinfo(hostbuf, portbuf, &hints, &res) != 0)
+      mrb_sys_fail(mrb, "getaddrinfo");
+    // XXX: try all addresses?
+    n = sendto(s, msg, hlen, flags, res->ai_addr, res->ai_addrlen);
+    freeaddrinfo(res);
+  }
+  if (n == -1)
+    mrb_sys_fail(mrb, "send");
+  return mrb_fixnum_value(n);
+}
+
+static mrb_value
+mrb_socket_gethostname(mrb_state *mrb, mrb_value cls)
+{
+  mrb_value buf;
+  
+#ifdef HOST_NAME_MAX
+  buf = mrb_str_buf_new(mrb, HOST_NAME_MAX+1);
+#else
+  buf = mrb_str_buf_new(mrb, 256);
+#endif
+  if (gethostname(RSTRING_PTR(buf), RSTRING_LEN(buf)) != 0)
+    mrb_sys_fail(mrb, "gethostname");
+  return buf;
+}
+
+static mrb_value
+mrb_socket_accept(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value ary, sastr;
+  int s1;
+  mrb_int s0;
+  socklen_t socklen;
+
+  mrb_get_args(mrb, "i", &s0);
+  socklen = sizeof(struct sockaddr_storage);
+  sastr = mrb_str_buf_new(mrb, socklen);
+  s1 = accept(s0, (struct sockaddr *)RSTRING_PTR(sastr), &socklen);
+  if (s1 == -1) {
+    mrb_sys_fail(mrb, "accept");
+  }
+  // XXX: possible descriptor leakage here!
+  mrb_str_resize(mrb, sastr, socklen);
+  ary = mrb_ary_new_capa(mrb, 2);
+  mrb_ary_push(mrb, ary, mrb_fixnum_value(s1));
+  mrb_ary_push(mrb, ary, sastr);
+  return ary;
+}
+
+static mrb_value
+mrb_socket_bind(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value sastr;
+  int s;
+
+  mrb_get_args(mrb, "iS", &s, &sastr);
+  if (bind(s, (struct sockaddr *)RSTRING_PTR(sastr), (socklen_t)RSTRING_LEN(sastr)) == -1) {
+    mrb_sys_fail(mrb, "bind");
+  }
+  return mrb_nil_value();
+}
+
+static mrb_value
+mrb_socket_connect(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value sastr;
+  int s;
+
+  mrb_get_args(mrb, "iS", &s, &sastr);
+  if (connect(s, (struct sockaddr *)RSTRING_PTR(sastr), (socklen_t)RSTRING_LEN(sastr)) == -1) {
+    mrb_sys_fail(mrb, "connect");
+  }
+  return mrb_nil_value();
+}
+
+static mrb_value
+mrb_socket_listen(mrb_state *mrb, mrb_value klass)
+{
+  int backlog, s;
+
+  mrb_get_args(mrb, "ii", &s, &backlog);
+  if (listen(s, backlog) == -1) {
+    mrb_sys_fail(mrb, "listen");
+  }
+  return mrb_nil_value();
+}
+
+static mrb_value
+mrb_socket_sockaddr_family(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value sa;
+
+  mrb_get_args(mrb, "S", &sa);
+  if (RSTRING_LEN(sa) < sizeof(struct sockaddr)) {
+    mrb_raisef(mrb, E_SOCKET_ERROR, "invalid sockaddr (too short)");
+  }
+  return mrb_fixnum_value(((struct sockaddr *)RSTRING_PTR(sa))->sa_family);
+}
+
+static mrb_value
+mrb_socket_sockaddr_un(mrb_state *mrb, mrb_value klass)
+{
+  struct sockaddr_un *sunp;
+  mrb_value path, s;
+  
+  mrb_get_args(mrb, "S", &path);
+  if (RSTRING_LEN(path) > sizeof(sunp->sun_path) - 1) {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "too long unix socket path (max: %ubytes)", (unsigned int)sizeof(sunp->sun_path) - 1);
+  }
+  s = mrb_str_buf_new(mrb, sizeof(struct sockaddr_un));
+  sunp = (struct sockaddr_un *)RSTRING_PTR(s);
+  sunp->sun_family = AF_UNIX;
+  memcpy(sunp->sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
+  sunp->sun_path[RSTRING_LEN(path)] = '\0';
+  mrb_str_resize(mrb, s, sizeof(struct sockaddr_un));
+  return s;
+}
+
+static mrb_value
+mrb_socket_socketpair(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value ary;
+  mrb_int domain, type, protocol;
+  int sv[2];
+
+  mrb_get_args(mrb, "iii", &domain, &type, &protocol);
+  if (socketpair(domain, type, protocol, sv) == -1) {
+    mrb_sys_fail(mrb, "socketpair");
+  }
+  // XXX: possible descriptor leakage here!
+  ary = mrb_ary_new_capa(mrb, 2);
+  mrb_ary_push(mrb, ary, mrb_fixnum_value(sv[0]));
+  mrb_ary_push(mrb, ary, mrb_fixnum_value(sv[1]));
+  return ary;
+}
+
+static mrb_value
+mrb_socket_socket(mrb_state *mrb, mrb_value klass)
+{
+  mrb_int domain, type, protocol;
+  int s;
+
+  mrb_get_args(mrb, "iii", &domain, &type, &protocol);
+  s = socket(domain, type, protocol);
+  if (s == -1)
+    mrb_sys_fail(mrb, "socket");
+  return mrb_fixnum_value(s);
+}
+
+void
+mrb_mruby_socket_gem_init(mrb_state* mrb)
+{
+  struct RClass *io, *ai, *sock, *bsock, *ipsock, *tcpsock, *udpsock, *usock;
+  struct RClass *constants;
+
+  ai = mrb_define_class(mrb, "Addrinfo", mrb->object_class);
+  mrb_mod_cv_set(mrb, ai, mrb_intern_cstr(mrb, "_lastai"), mrb_nil_value());
+  mrb_define_class_method(mrb, ai, "getaddrinfo", mrb_addrinfo_getaddrinfo, ARGS_REQ(2)|ARGS_OPT(4));
+  mrb_define_method(mrb, ai, "getnameinfo", mrb_addrinfo_getnameinfo, ARGS_OPT(1));
+  mrb_define_method(mrb, ai, "unix_path", mrb_addrinfo_unix_path, ARGS_NONE());
+
+  io = mrb_class_get(mrb, "IO");
+
+  bsock = mrb_define_class(mrb, "BasicSocket", io);
+  mrb_define_method(mrb, bsock, "_recvfrom", mrb_basicsocket_recvfrom, ARGS_REQ(1)|ARGS_OPT(1));
+  mrb_define_method(mrb, bsock, "_setnonblock", mrb_basicsocket_setnonblock, ARGS_REQ(1));
+  mrb_define_method(mrb, bsock, "getpeereid", mrb_basicsocket_getpeereid, ARGS_NONE());
+  mrb_define_method(mrb, bsock, "getpeername", mrb_basicsocket_getpeername, ARGS_NONE());
+  mrb_define_method(mrb, bsock, "getsockname", mrb_basicsocket_getsockname, ARGS_NONE());
+  mrb_define_method(mrb, bsock, "getsockopt", mrb_basicsocket_getsockopt, ARGS_REQ(2));
+  mrb_define_method(mrb, bsock, "recv", mrb_basicsocket_recv, ARGS_REQ(1)|ARGS_OPT(1));
+  // #recvmsg(maxlen, flags=0)
+  mrb_define_method(mrb, bsock, "send", mrb_basicsocket_send, ARGS_REQ(2)|ARGS_OPT(1));
+  // #sendmsg
+  // #sendmsg_nonblock
+  mrb_define_method(mrb, bsock, "setsockopt", mrb_basicsocket_setsockopt, ARGS_REQ(1)|ARGS_OPT(2));
+  mrb_define_method(mrb, bsock, "shutdown", mrb_basicsocket_shutdown, ARGS_OPT(1));
+
+  ipsock = mrb_define_class(mrb, "IPSocket", bsock);
+  mrb_define_class_method(mrb, ipsock, "ntop", mrb_ipsocket_ntop, ARGS_REQ(1));
+  mrb_define_class_method(mrb, ipsock, "pton", mrb_ipsocket_pton, ARGS_REQ(2));
+  mrb_define_method(mrb, ipsock, "recvfrom", mrb_ipsocket_recvfrom, ARGS_REQ(1)|ARGS_OPT(1));
+
+  tcpsock = mrb_define_class(mrb, "TCPSocket", ipsock);
+  //mrb_define_class_method(mrb, tcpsock, "open", mrb_tcpsocket_open, ARGS_REQ(2)|ARGS_OPT(2));
+  //mrb_define_class_method(mrb, tcpsock, "new", mrb_tcpsocket_open, ARGS_REQ(2)|ARGS_OPT(2));
+  mrb_define_class(mrb, "TCPServer", tcpsock);
+
+  udpsock = mrb_define_class(mrb, "UDPSocket", ipsock);
+  //#recvfrom_nonblock
+
+  sock = mrb_define_class(mrb, "Socket", bsock);
+  mrb_define_class_method(mrb, sock, "_accept", mrb_socket_accept, ARGS_REQ(1));
+  mrb_define_class_method(mrb, sock, "_bind", mrb_socket_bind, ARGS_REQ(3));
+  mrb_define_class_method(mrb, sock, "_connect", mrb_socket_connect, ARGS_REQ(3));
+  mrb_define_class_method(mrb, sock, "_listen", mrb_socket_listen, ARGS_REQ(2));
+  mrb_define_class_method(mrb, sock, "_sockaddr_family", mrb_socket_sockaddr_family, ARGS_REQ(1));
+  mrb_define_class_method(mrb, sock, "_socket", mrb_socket_socket, ARGS_REQ(3));
+  //mrb_define_class_method(mrb, sock, "gethostbyaddr", mrb_socket_gethostbyaddr, ARGS_REQ(1)|ARGS_OPT(1));
+  //mrb_define_class_method(mrb, sock, "gethostbyname", mrb_socket_gethostbyname, ARGS_REQ(1)|ARGS_OPT(1));
+  mrb_define_class_method(mrb, sock, "gethostname", mrb_socket_gethostname, ARGS_NONE());
+  //mrb_define_class_method(mrb, sock, "getservbyname", mrb_socket_getservbyname, ARGS_REQ(1)|ARGS_OPT(1));
+  //mrb_define_class_method(mrb, sock, "getservbyport", mrb_socket_getservbyport, ARGS_REQ(1)|ARGS_OPT(1));
+  mrb_define_class_method(mrb, sock, "sockaddr_un", mrb_socket_sockaddr_un, ARGS_REQ(1));
+  mrb_define_class_method(mrb, sock, "socketpair", mrb_socket_socketpair, ARGS_REQ(3));
+  //mrb_define_method(mrb, sock, "sysaccept", mrb_socket_accept, ARGS_NONE());
+
+  usock = mrb_define_class(mrb, "UNIXSocket", io);
+  //mrb_define_class_method(mrb, usock, "pair", mrb_unixsocket_open, ARGS_OPT(2));
+  //mrb_define_class_method(mrb, usock, "socketpair", mrb_unixsocket_open, ARGS_OPT(2));
+
+  //mrb_define_method(mrb, usock, "recv_io", mrb_unixsocket_peeraddr, ARGS_NONE());
+  //mrb_define_method(mrb, usock, "recvfrom", mrb_unixsocket_peeraddr, ARGS_NONE());
+  //mrb_define_method(mrb, usock, "send_io", mrb_unixsocket_peeraddr, ARGS_NONE());
+
+  constants = mrb_define_module_under(mrb, sock, "Constants");
+
+#define define_const(SYM) \
+  do {								\
+    mrb_define_const(mrb, constants, #SYM, mrb_fixnum_value(SYM));	\
+  } while (0)
+
+#include "const.cstub"
+}
+
+void
+mrb_mruby_socket_gem_final(mrb_state* mrb)
+{
+  mrb_value ai;
+  ai = mrb_mod_cv_get(mrb, mrb_class_get(mrb, "Addrinfo"), mrb_intern_cstr(mrb, "_lastai"));
+  if (mrb_voidp_p(ai)) {
+    freeaddrinfo(mrb_voidp(ai));
+  }
+}

test/socket.rb

+assert('Addrinfo') do
+  assert_equal(Class, Addrinfo.class)
+end
+
+assert('super class of Addrinfo') do
+  assert_equal(Object, Addrinfo.superclass)
+end
+
+assert('Addrinfo.getadrinfo') do
+  ary = Addrinfo.getaddrinfo("localhost", "domain", Socket::AF_INET, Socket::SOCK_STREAM)
+  assert_equal(ary.size, 1)
+  ai = ary[0]
+  assert_equal(ai.afamily, Socket::AF_INET)
+  assert_equal(ai.pfamily, Socket::PF_INET)
+  assert_equal(ai.socktype, Socket::SOCK_STREAM)
+  assert_equal(ai.ip_address, '127.0.0.1')
+  assert_equal(ai.ip_port, 53)
+end
+
+assert('Addrinfo.foreach') do
+  # assume Addrinfo.getaddrinfo works well
+  b = []
+  a = Addrinfo.foreach("localhost", "domain") { |ai|
+    assert_include([Socket::AF_INET, Socket::AF_INET6], ai.afamily)
+    if ai.afamily == Socket::AF_INET
+      assert_equal(ai.ip_address, '127.0.0.1')
+    else
+      assert_equal(ai.ip_address, '::1')
+    end
+    assert_equal(ai.ip_port, 53)
+    assert_include([Socket::SOCK_STREAM, Socket::SOCK_DGRAM], ai.socktype)
+    b << ai
+  }
+  assert_equal(a.size, b.size)
+end
+
+assert('Addrinfo.ip') do
+  ai = Addrinfo.ip('127.0.0.1')
+  assert_equal('127.0.0.1', ai.ip_address)
+  assert_equal(Socket::AF_INET, ai.afamily)
+  assert_equal(0, ai.ip_port)
+  assert_equal(0, ai.socktype)
+  assert_equal(0, ai.protocol)
+end
+
+assert('Addrinfo.tcp') do
+  ai = Addrinfo.tcp('127.0.0.1', 'smtp')
+  assert_equal('127.0.0.1', ai.ip_address)
+  assert_equal(Socket::AF_INET, ai.afamily)
+  assert_equal(25, ai.ip_port)
+  assert_equal(Socket::SOCK_STREAM, ai.socktype)
+  assert_equal(Socket::IPPROTO_TCP, ai.protocol)
+end
+
+assert('Addrinfo.udp') do
+  ai = Addrinfo.udp('127.0.0.1', 'domain')
+  assert_equal('127.0.0.1', ai.ip_address)
+  assert_equal(Socket::AF_INET, ai.afamily)
+  assert_equal(53, ai.ip_port)
+  assert_equal(Socket::SOCK_DGRAM, ai.socktype)
+  assert_equal(Socket::IPPROTO_UDP, ai.protocol)
+end
+
+assert('Addrinfo.unix') do
+  a1 = Addrinfo.unix('/tmp/sock')
+  assert_true(a1.unix?)
+  assert_equal('/tmp/sock', a1.unix_path)
+  assert_equal(Socket::SOCK_STREAM, a1.socktype)
+  a2 = Addrinfo.unix('/tmp/sock', Socket::SOCK_DGRAM)
+  assert_equal(Socket::SOCK_DGRAM, a2.socktype)
+end
+
+assert('Addrinfo#afamily') do
+  ai4 = Addrinfo.new(Socket.sockaddr_in(1, '127.0.0.1'))
+  ai6 = Addrinfo.new(Socket.sockaddr_in(1, '::1'))
+  aiu = Addrinfo.new(Socket.sockaddr_un('/tmp/sock'))
+  assert_equal(Socket::AF_INET, ai4.afamily)
+  assert_equal(Socket::AF_INET6, ai6.afamily)
+  assert_equal(Socket::AF_UNIX, aiu.afamily)
+end
+
+# assert('Addrinfo#canonname') do
+
+# #getnameinfo
+# assert('Addrinfo#inspect') do
+# assert('Addrinfo#inspect_socket') do
+# assert('Addrinfo#ip?') do
+# assert('Addrinfo#ip_address') do
+# assert('Addrinfo#ip_port') do
+# assert('Addrinfo#ip_unpack') do
+# assert('Addrinfo#ipv4?') do
+# assert('Addrinfo#ipv6?') do
+# assert('Addrinfo#pfamily') do
+# assert('Addrinfo#protocol') do
+# assert('Addrinfo#socktype') do
+# assert('Addrinfo#to_sockaddr') do
+# assert('Addrinfo#unix?') do
+# #unix_path
+
+
+assert('BasicSocket') do
+  assert_equal(Class, BasicSocket.class)
+end
+
+assert('super class of BasicSocket') do
+  assert_equal(IO, BasicSocket.superclass)
+end
+
+assert('BasicSocket.do_not_reverse_lookup') do
+  assert_equal(BasicSocket.do_not_reverse_lookup, true)
+end
+
+assert('BasicSocket.do_not_reverse_lookup=') do
+  BasicSocket.do_not_reverse_lookup = false
+  assert_equal(BasicSocket.do_not_reverse_lookup, false)
+  BasicSocket.do_not_reverse_lookup = true
+end
+
+assert('UDPSocket.new') do
+  s = UDPSocket.new
+  assert_true(s.is_a? UDPSocket)
+  s.close
+  s = UDPSocket.new(Socket::AF_INET6)
+  assert_true(s.is_a? UDPSocket)
+  s.close
+  true
+end
+
+#assert('UDPSocket#connect') do
+#assert('UDPSocket#send') do
+#assert('UDPSocket#recv') do
+
+#assert('UDPSocket#bind') do
+#assert('UDPSocket#recvfrom_nonblock') do
+
+#assert('TCPSocket.gethostbyname') do
+#assert('TCPSocket.new') do
+#assert('TCPSocket#close') do
+#assert('TCPSocket#write') do