text: #include "rubysocket.h"
  
  VALUE rb_cSockOpt;
  
  static VALUE
  constant_to_sym(int constant, ID (*intern_const)(int))
  {
      ID name = intern_const(constant);
      if (name) {
          return ID2SYM(name);
      }
  
      return INT2NUM(constant);
  }
  
  static VALUE
  optname_to_sym(int level, int optname)
  {
      switch (level) {
        case SOL_SOCKET:
          return constant_to_sym(optname, rsock_intern_so_optname);
        case IPPROTO_IP:
          return constant_to_sym(optname, rsock_intern_ip_optname);
  #ifdef INET6
        case IPPROTO_IPV6:
          return constant_to_sym(optname, rsock_intern_ipv6_optname);
  #endif
        case IPPROTO_TCP:
          return constant_to_sym(optname, rsock_intern_tcp_optname);
        case IPPROTO_UDP:
          return constant_to_sym(optname, rsock_intern_udp_optname);
        default:
          return INT2NUM(optname);
      }
  }
  
  /*
   * call-seq:
   *   Socket::Option.new(family, level, optname, data) => sockopt
   *
   * Returns a new Socket::Option object.
   *
   *   sockopt = Socket::Option.new(:INET, :SOCKET, :KEEPALIVE, [1].pack("i"))
   *   p sockopt #=> #<Socket::Option: INET SOCKET KEEPALIVE 1>
   *
   */
  static VALUE
  sockopt_initialize(VALUE self, VALUE vfamily, VALUE vlevel, VALUE voptname, VALUE data)
  {
      int family = rsock_family_arg(vfamily);
      int level = rsock_level_arg(family, vlevel);
      int optname = rsock_optname_arg(family, level, voptname);
      StringValue(data);
      rb_ivar_set(self, rb_intern("family"), INT2NUM(family));
      rb_ivar_set(self, rb_intern("level"), INT2NUM(level));
      rb_ivar_set(self, rb_intern("optname"), INT2NUM(optname));
      rb_ivar_set(self, rb_intern("data"), data);
      return self;
  }
  
  VALUE
  rsock_sockopt_new(int family, int level, int optname, VALUE data)
  {
      NEWOBJ(obj, struct RObject);
      OBJSETUP(obj, rb_cSockOpt, T_OBJECT);
      StringValue(data);
      sockopt_initialize((VALUE)obj, INT2NUM(family), INT2NUM(level), INT2NUM(optname), data);
      return (VALUE)obj;
  }
  
  /*
   * call-seq:
   *   sockopt.family => integer
   *
   * returns the socket family as an integer.
   *
   *   p Socket::Option.new(:INET6, :IPV6, :RECVPKTINFO, [1].pack("i!")).family
   *   #=> 10
   */
  static VALUE
  sockopt_family_m(VALUE self)
  {
      return rb_attr_get(self, rb_intern("family"));
  }
  
  static int
  sockopt_level(VALUE self)
  {
      return NUM2INT(rb_attr_get(self, rb_intern("level")));
  }
  
  /*
   * call-seq:
   *   sockopt.level => integer
   *
   * returns the socket level as an integer.
   *
   *   p Socket::Option.new(:INET6, :IPV6, :RECVPKTINFO, [1].pack("i!")).level
   *   #=> 41
   */
  static VALUE
  sockopt_level_m(VALUE self)
  {
      return INT2NUM(sockopt_level(self));
  }
  
  static int
  sockopt_optname(VALUE self)
  {
      return NUM2INT(rb_attr_get(self, rb_intern("optname")));
  }
  
  /*
   * call-seq:
   *   sockopt.optname => integer
   *
   * returns the socket option name as an integer.
   *
   *   p Socket::Option.new(:INET6, :IPV6, :RECVPKTINFO, [1].pack("i!")).optname
   *   #=> 2
   */
  static VALUE
  sockopt_optname_m(VALUE self)
  {
      return INT2NUM(sockopt_optname(self));
  }
  
  /*
   * call-seq:
   *   sockopt.data => string
   *
   * returns the socket option data as a string.
   *
   *   p Socket::Option.new(:INET6, :IPV6, :RECVPKTINFO, [1].pack("i!")).data
   *   #=> "\x01\x00\x00\x00"
   */
  static VALUE
  sockopt_data(VALUE self)
  {
      VALUE v = rb_attr_get(self, rb_intern("data"));
      StringValue(v);
      return v;
  }
  
  /*
   * call-seq:
   *   Socket::Option.int(family, level, optname, integer) => sockopt
   *
   * Creates a new Socket::Option object which contains an int as data.
   *
   * The size and endian is dependent on the host. 
   *
   *   p Socket::Option.int(:INET, :SOCKET, :KEEPALIVE, 1)
   *   #=> #<Socket::Option: INET SOCKET KEEPALIVE 1>
   */
  static VALUE
  sockopt_s_int(VALUE klass, VALUE vfamily, VALUE vlevel, VALUE voptname, VALUE vint)
  {
      int family = rsock_family_arg(vfamily);
      int level = rsock_level_arg(family, vlevel);
      int optname = rsock_optname_arg(family, level, voptname);
      int i = NUM2INT(vint);
      return rsock_sockopt_new(family, level, optname, rb_str_new((char*)&i, sizeof(i)));
  }
  
  /*
   * call-seq:
   *   sockopt.int => integer
   *
   * Returns the data in _sockopt_ as an int.
   *
   * The size and endian is dependent on the host. 
   *
   *   sockopt = Socket::Option.int(:INET, :SOCKET, :KEEPALIVE, 1)
   *   p sockopt.int => 1
   */
  static VALUE
  sockopt_int(VALUE self)
  {
      int i;
      VALUE data = sockopt_data(self);
      StringValue(data);
      if (RSTRING_LEN(data) != sizeof(int))
          rb_raise(rb_eTypeError, "size differ.  expected as sizeof(int)=%d but %ld",
                   (int)sizeof(int), (long)RSTRING_LEN(data));
      memcpy((char*)&i, RSTRING_PTR(data), sizeof(int));
      return INT2NUM(i);
  }
  
  /*
   * call-seq:
   *   Socket::Option.bool(family, level, optname, bool) => sockopt
   *
   * Creates a new Socket::Option object which contains boolean as data.
   * Actually 0 or 1 as int is used.
   *
   *   p Socket::Option.bool(:INET, :SOCKET, :KEEPALIVE, true)
   *   #=> #<Socket::Option: INET SOCKET KEEPALIVE 1>
   *
   *   p Socket::Option.bool(:INET, :SOCKET, :KEEPALIVE, false)
   *   #=> #<Socket::Option: AF_INET SOCKET KEEPALIVE 0>
   *
   */
  static VALUE
  sockopt_s_bool(VALUE klass, VALUE vfamily, VALUE vlevel, VALUE voptname, VALUE vbool)
  {
      int family = rsock_family_arg(vfamily);
      int level = rsock_level_arg(family, vlevel);
      int optname = rsock_optname_arg(family, level, voptname);
      int i = RTEST(vbool) ? 1 : 0;
      return rsock_sockopt_new(family, level, optname, rb_str_new((char*)&i, sizeof(i)));
  }
  
  /*
   * call-seq:
   *   sockopt.bool => true or false
   *
   * Returns the data in _sockopt_ as an boolean value.
   *
   *   sockopt = Socket::Option.int(:INET, :SOCKET, :KEEPALIVE, 1)
   *   p sockopt.bool => true
   */
  static VALUE
  sockopt_bool(VALUE self)
  {
      int i;
      VALUE data = sockopt_data(self);
      StringValue(data);
      if (RSTRING_LEN(data) != sizeof(int))
          rb_raise(rb_eTypeError, "size differ.  expected as sizeof(int)=%d but %ld",
                   (int)sizeof(int), (long)RSTRING_LEN(data));
      memcpy((char*)&i, RSTRING_PTR(data), sizeof(int));
      return i == 0 ? Qfalse : Qtrue;
  }
  
  /*
   * call-seq:
   *   Socket::Option.linger(onoff, secs) => sockopt
   *
   * Creates a new Socket::Option object for SOL_SOCKET/SO_LINGER.
   *
   * _onoff_ should be an integer or a boolean.
   *
   * _secs_ should be the number of seconds.
   *
   *   p Socket::Option.linger(true, 10)
   *   #=> #<Socket::Option: UNSPEC SOCKET LINGER on 10sec>
   *
   */
  static VALUE
  sockopt_s_linger(VALUE klass, VALUE vonoff, VALUE vsecs)
  {
      VALUE tmp;
      struct linger l;
      memset(&l, 0, sizeof(l));
      if (!NIL_P(tmp = rb_check_to_integer(vonoff, "to_int")))
          l.l_onoff = NUM2INT(tmp);
      else
          l.l_onoff = RTEST(vonoff) ? 1 : 0;
      l.l_linger = NUM2INT(vsecs);
      return rsock_sockopt_new(AF_UNSPEC, SOL_SOCKET, SO_LINGER, rb_str_new((char*)&l, sizeof(l)));
  }
  
  /*
   * call-seq:
   *   sockopt.linger => [bool, seconds]
   *
   * Returns the linger data in _sockopt_ as a pair of boolean and integer.
   *
   *   sockopt = Socket::Option.linger(true, 10)
   *   p sockopt.linger => [true, 10]
   */
  static VALUE
  sockopt_linger(VALUE self)
  {
      int level = sockopt_level(self);
      int optname = sockopt_optname(self);
      VALUE data = sockopt_data(self);
      struct linger l;
      VALUE vonoff, vsecs;
  
      if (level != SOL_SOCKET || optname != SO_LINGER)
          rb_raise(rb_eTypeError, "linger socket option expected"); 
      if (RSTRING_LEN(data) != sizeof(l))
          rb_raise(rb_eTypeError, "size differ.  expected as sizeof(struct linger)=%d but %ld",
                   (int)sizeof(struct linger), (long)RSTRING_LEN(data));
      memcpy((char*)&l, RSTRING_PTR(data), sizeof(struct linger));
      switch (l.l_onoff) {
        case 0: vonoff = Qfalse; break;
        case 1: vonoff = Qtrue; break;
        default: vonoff = INT2NUM(l.l_onoff); break;
      }
      vsecs = INT2NUM(l.l_linger);
      return rb_assoc_new(vonoff, vsecs);
  }
  
  static int
  inspect_int(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(int)) {
          int i;
          memcpy((char*)&i, RSTRING_PTR(data), sizeof(int));
          rb_str_catf(ret, " %d", i);
          return 1;
      }
      else {
          return 0;
      }
  }
  
  static int
  inspect_errno(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(int)) {
          int i;
          char *err;
          memcpy((char*)&i, RSTRING_PTR(data), sizeof(int));
          err = strerror(i);
          rb_str_catf(ret, " %s (%d)", err, i);
          return 1;
      }
      else {
          return 0;
      }
  }
  
  #if defined(IPV6_MULTICAST_IF) || defined(IPV6_MULTICAST_LOOP)
  static int
  inspect_uint(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(int)) {
          unsigned int i;
          memcpy((char*)&i, RSTRING_PTR(data), sizeof(unsigned int));
          rb_str_catf(ret, " %u", i);
          return 1;
      }
      else {
          return 0;
      }
  }
  #endif
  
  #if defined(SOL_SOCKET) && defined(SO_LINGER) /* POSIX */
  static int
  inspect_linger(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(struct linger)) {
          struct linger s;
          memcpy((char*)&s, RSTRING_PTR(data), sizeof(s));
          switch (s.l_onoff) {
            case 0: rb_str_cat2(ret, " off"); break;
            case 1: rb_str_cat2(ret, " on"); break;
            default: rb_str_catf(ret, " on(%d)", s.l_onoff); break;
          }
          rb_str_catf(ret, " %dsec", s.l_linger);
          return 1;
      }
      else {
          return 0;
      }
  }
  #endif
  
  #if defined(SOL_SOCKET) && defined(SO_TYPE) /* POSIX */
  static int
  inspect_socktype(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(int)) {
          int i;
          ID id;
          memcpy((char*)&i, RSTRING_PTR(data), sizeof(int));
          id = rsock_intern_socktype(i);
          if (id)
              rb_str_catf(ret, " %s", rb_id2name(id));
          else
              rb_str_catf(ret, " %d", i);
          return 1;
      }
      else {
          return 0;
      }
  }
  #endif
  
  static int
  inspect_timeval_as_interval(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(struct timeval)) {
          struct timeval s;
          memcpy((char*)&s, RSTRING_PTR(data), sizeof(s));
          rb_str_catf(ret, " %ld.%06ldsec", (long)s.tv_sec, (long)s.tv_usec);
          return 1;
      }
      else {
          return 0;
      }
  }
  
  #if defined(SOL_SOCKET) && defined(SO_PEERCRED) /* GNU/Linux */
  static int
  inspect_peercred(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(struct ucred)) {
          struct ucred cred;
          memcpy(&cred, RSTRING_PTR(data), sizeof(struct ucred));
          rb_str_catf(ret, " pid=%u euid=%u egid=%u",
  		    (unsigned)cred.pid, (unsigned)cred.uid, (unsigned)cred.gid);
          rb_str_cat2(ret, " (ucred)");
          return 1;
      }
      else {
          return 0;
      }
  }
  #endif
  
  #if defined(LOCAL_PEERCRED) /* FreeBSD, MacOS X */
  static int
  inspect_local_peercred(int level, int optname, VALUE data, VALUE ret)
  {
      if (RSTRING_LEN(data) == sizeof(struct xucred)) {
          struct xucred cred;
          memcpy(&cred, RSTRING_PTR(data), sizeof(struct xucred));
          if (cred.cr_version != XUCRED_VERSION)
              return 0;
          rb_str_catf(ret, " version=%u", cred.cr_version);
          rb_str_catf(ret, " euid=%u", cred.cr_uid);
  	if (cred.cr_ngroups) {
  	    int i;
  	    const char *sep = " groups=";
  	    for (i = 0; i < cred.cr_ngroups; i++) {
  		rb_str_catf(ret, "%s%u", sep, cred.cr_groups[i]);
  		sep = ",";
  	    }
  	}
          rb_str_cat2(ret, " (xucred)");
          return 1;
      }
      else {
          return 0;
      }
  }
  #endif
  
  
  /*
   * call-seq:
   *   sockopt.inspect => string
   *
   * Returns a string which shows sockopt in human-readable form.
   *
   *   p Socket::Option.new(:INET, :SOCKET, :KEEPALIVE, [1].pack("i")).inspect
   *   #=> "#<Socket::Option: INET SOCKET KEEPALIVE 1>"
   *
   */
  static VALUE
  sockopt_inspect(VALUE self)
  {
      int family = NUM2INT(sockopt_family_m(self));
      int level = NUM2INT(sockopt_level_m(self));
      int optname = NUM2INT(sockopt_optname_m(self));
      VALUE data = sockopt_data(self);
      VALUE v, ret;
      ID family_id, level_id, optname_id;
      int inspected;
  
      StringValue(data);
  
      ret = rb_sprintf("#<%s:", rb_obj_classname(self));
  
      family_id = rsock_intern_family_noprefix(family);
      if (family_id)
  	rb_str_catf(ret, " %s", rb_id2name(family_id));
      else
          rb_str_catf(ret, " family:%d", family);
  
      if (level == SOL_SOCKET) {
          rb_str_cat2(ret, " SOCKET");
  
  	optname_id = rsock_intern_so_optname(optname);
  	if (optname_id)
  	    rb_str_catf(ret, " %s", rb_id2name(optname_id));
  	else
  	    rb_str_catf(ret, " optname:%d", optname);
      }
  #ifdef HAVE_SYS_UN_H
      else if (family == AF_UNIX) {
  	rb_str_catf(ret, " level:%d", level);
  
  	optname_id = rsock_intern_local_optname(optname);
  	if (optname_id)
  	    rb_str_catf(ret, " %s", rb_id2name(optname_id));
  	else
  	    rb_str_catf(ret, " optname:%d", optname);
      }
  #endif
      else if (IS_IP_FAMILY(family)) {
  	level_id = rsock_intern_iplevel(level);
  	if (level_id)
  	    rb_str_catf(ret, " %s", rb_id2name(level_id));
  	else
  	    rb_str_catf(ret, " level:%d", level);
  
  	v = optname_to_sym(level, optname);
  	if (SYMBOL_P(v))
  	    rb_str_catf(ret, " %s", rb_id2name(SYM2ID(v)));
  	else
  	    rb_str_catf(ret, " optname:%d", optname);
      }
      else {
          rb_str_catf(ret, " level:%d", level);
          rb_str_catf(ret, " optname:%d", optname);
      }
  
      inspected = 0;
  
      if (level == SOL_SOCKET)
          family = AF_UNSPEC;
      switch (family) {
        case AF_UNSPEC:
          switch (level) {
            case SOL_SOCKET:
              switch (optname) {
  #            if defined(SO_DEBUG) /* POSIX */
                case SO_DEBUG: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_ERROR) /* POSIX */
                case SO_ERROR: inspected = inspect_errno(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_TYPE) /* POSIX */
                case SO_TYPE: inspected = inspect_socktype(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_ACCEPTCONN) /* POSIX */
                case SO_ACCEPTCONN: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_BROADCAST) /* POSIX */
                case SO_BROADCAST: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_REUSEADDR) /* POSIX */
                case SO_REUSEADDR: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_KEEPALIVE) /* POSIX */
                case SO_KEEPALIVE: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_OOBINLINE) /* POSIX */
                case SO_OOBINLINE: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_SNDBUF) /* POSIX */
                case SO_SNDBUF: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_RCVBUF) /* POSIX */
                case SO_RCVBUF: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_DONTROUTE) /* POSIX */
                case SO_DONTROUTE: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_RCVLOWAT) /* POSIX */
                case SO_RCVLOWAT: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_SNDLOWAT) /* POSIX */
                case SO_SNDLOWAT: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_LINGER) /* POSIX */
                case SO_LINGER: inspected = inspect_linger(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_RCVTIMEO) /* POSIX */
                case SO_RCVTIMEO: inspected = inspect_timeval_as_interval(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_SNDTIMEO) /* POSIX */
                case SO_SNDTIMEO: inspected = inspect_timeval_as_interval(level, optname, data, ret); break;
  #            endif
  #            if defined(SO_PEERCRED) /* GNU/Linux */
                case SO_PEERCRED: inspected = inspect_peercred(level, optname, data, ret); break;
  #            endif
              }
              break;
          }
          break;
  
        case AF_INET:
  #ifdef INET6
        case AF_INET6:
  #endif
          switch (level) {
  #        if defined(IPPROTO_IPV6)
            case IPPROTO_IPV6:
              switch (optname) {
                /* IPV6_JOIN_GROUP ipv6_mreq, IPV6_LEAVE_GROUP ipv6_mreq */
  #            if defined(IPV6_MULTICAST_HOPS) /* POSIX */
                case IPV6_MULTICAST_HOPS: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(IPV6_MULTICAST_IF) /* POSIX */
                case IPV6_MULTICAST_IF: inspected = inspect_uint(level, optname, data, ret); break;
  #            endif
  #            if defined(IPV6_MULTICAST_LOOP) /* POSIX */
                case IPV6_MULTICAST_LOOP: inspected = inspect_uint(level, optname, data, ret); break;
  #            endif
  #            if defined(IPV6_UNICAST_HOPS) /* POSIX */
                case IPV6_UNICAST_HOPS: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
  #            if defined(IPV6_V6ONLY) /* POSIX */
                case IPV6_V6ONLY: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
              }
              break;
  #        endif
  
  #        if defined(IPPROTO_TCP)
            case IPPROTO_TCP:
              switch (optname) {
  #            if defined(TCP_NODELAY) /* POSIX */
                case TCP_NODELAY: inspected = inspect_int(level, optname, data, ret); break;
  #            endif
              }
              break;
  #        endif
          }
          break;
  
  #ifdef HAVE_SYS_UN_H
        case AF_UNIX:
          switch (level) {
            case 0:
              switch (optname) {
  #            if defined(LOCAL_PEERCRED)
                case LOCAL_PEERCRED: inspected = inspect_local_peercred(level, optname, data, ret); break;
  #            endif
              }
              break;
          }
          break;
  #endif
      }
  
      if (!inspected) {
          data = rb_str_dump(data);
          rb_str_catf(ret, " %s", StringValueCStr(data));
      }
  
      rb_str_cat2(ret, ">");
  
      return ret;
  }
  
  /*
   * call-seq:
   *   sockopt.unpack(template) => array
   *
   * Calls String#unpack on sockopt.data.
   *
   *   sockopt = Socket::Option.new(:INET, :SOCKET, :KEEPALIVE, [1].pack("i"))
   *   p sockopt.unpack("i")      #=> [1]
   *   p sockopt.data.unpack("i") #=> [1]
   */
  static VALUE
  sockopt_unpack(VALUE self, VALUE template)
  {
      return rb_funcall(sockopt_data(self), rb_intern("unpack"), 1, template);
  }
  
  void
  Init_sockopt(void)
  {
      /* for rdoc */
      /* rb_cSocket = rb_define_class("Socket", rb_cBasicSocket); */
  
      rb_cSockOpt = rb_define_class_under(rb_cSocket, "Option", rb_cObject);
      rb_define_method(rb_cSockOpt, "initialize", sockopt_initialize, 4);
      rb_define_method(rb_cSockOpt, "family", sockopt_family_m, 0);
      rb_define_method(rb_cSockOpt, "level", sockopt_level_m, 0);
      rb_define_method(rb_cSockOpt, "optname", sockopt_optname_m, 0);
      rb_define_method(rb_cSockOpt, "data", sockopt_data, 0);
      rb_define_method(rb_cSockOpt, "inspect", sockopt_inspect, 0);
  
      rb_define_singleton_method(rb_cSockOpt, "int", sockopt_s_int, 4);
      rb_define_method(rb_cSockOpt, "int", sockopt_int, 0);
  
      rb_define_singleton_method(rb_cSockOpt, "bool", sockopt_s_bool, 4);
      rb_define_method(rb_cSockOpt, "bool", sockopt_bool, 0);
  
      rb_define_singleton_method(rb_cSockOpt, "linger", sockopt_s_linger, 2);
      rb_define_method(rb_cSockOpt, "linger", sockopt_linger, 0);
  
      rb_define_method(rb_cSockOpt, "unpack", sockopt_unpack, 1);
  
      rb_define_method(rb_cSockOpt, "to_s", sockopt_data, 0); /* compatibility for ruby before 1.9.2 */
  }
  
  