class method
Socket.gethostbyaddr
(::String ip) -> [ ::String, ::Array[::String], ::Integer, ::String ]
Socket.gethostbyaddr(address_string [, address_family]) => hostent
ext/socket/socket.c
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static VALUE
sock_s_gethostbyaddr(int argc, VALUE *argv, VALUE _)
{
VALUE addr, family;
struct hostent *h;
char **pch;
VALUE ary, names;
int t = AF_INET;
rb_warn("Socket.gethostbyaddr is deprecated; use Addrinfo#getnameinfo instead.");
rb_scan_args(argc, argv, "11", &addr, &family);
StringValue(addr);
if (!NIL_P(family)) {
t = rsock_family_arg(family);
}
#ifdef AF_INET6
else if (RSTRING_LEN(addr) == 16) {
t = AF_INET6;
}
#endif
h = gethostbyaddr(RSTRING_PTR(addr), RSTRING_SOCKLEN(addr), t);
if (h == NULL) {
#ifdef HAVE_HSTRERROR
extern int h_errno;
rb_raise(rb_eSocket, "%s", (char*)hstrerror(h_errno));
#else
rb_raise(rb_eSocket, "host not found");
#endif
}
ary = rb_ary_new();
rb_ary_push(ary, rb_str_new2(h->h_name));
names = rb_ary_new();
rb_ary_push(ary, names);
if (h->h_aliases != NULL) {
for (pch = h->h_aliases; *pch; pch++) {
rb_ary_push(names, rb_str_new2(*pch));
}
}
rb_ary_push(ary, INT2NUM(h->h_addrtype));
#ifdef h_addr
for (pch = h->h_addr_list; *pch; pch++) {
rb_ary_push(ary, rb_str_new(*pch, h->h_length));
}
#else
rb_ary_push(ary, rb_str_new(h->h_addr, h->h_length));
#endif
return ary;
}
Use Addrinfo#getnameinfo instead. This method is deprecated for the following reasons:
-
Uncommon address representation: 4/16-bytes binary string to represent IPv4/IPv6 address.
-
gethostbyaddr() may take a long time and it may block other threads. (GVL cannot be released since gethostbyname() is not thread safe.)
-
This method uses gethostbyname() function already removed from POSIX.
This method obtains the host information for address.
p Socket.gethostbyaddr([221,186,184,68].pack("CCCC"))
#=> ["carbon.ruby-lang.org", [], 2, "\xDD\xBA\xB8D"]
p Socket.gethostbyaddr([127,0,0,1].pack("CCCC"))
["localhost", [], 2, "\x7F\x00\x00\x01"]
p Socket.gethostbyaddr(([0]*15+[1]).pack("C"*16))
#=> ["localhost", ["ip6-localhost", "ip6-loopback"], 10,
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"]