Extended maintenance of Ruby versions 1.8.7 and 1.9.2 will end on July 31, 2014. Read more

In Files

  • socket/socket.c

Parent

TCPSocket

Public Class Methods

gethostbyname(host) => hostent click to toggle source

Resolve host and return name and address information for it, similarly to gethostbyname(3). host can be a domain name or the presentation format of an address.

Returns an array of information similar to that found in a +struct hostent+:

- cannonical name: the cannonical name for host in the DNS, or a
  string representing the address
- aliases: an array of aliases for the canonical name, there may be no aliases
- address family: usually one of Socket::AF_INET or Socket::AF_INET6
- address: a string, the binary value of the +struct sockaddr+ for this name, in
  the indicated address family
- ...: if there are multiple addresses for this host,  a series of
  strings/+struct sockaddr+s may follow, not all necessarily in the same
  address family. Note that the fact that they may not be all in the same
  address family is a departure from the behaviour of gethostbyname(3).

Note: I believe that the fact that the multiple addresses returned are not necessarily in the same address family may be a bug, since if this function actually called gethostbyname(3), ALL the addresses returned in the trailing address list (h_addr_list from struct hostent) would be of the same address family! Examples from my system, OS X 10.3:

["localhost", [], 30, "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\001", "\177\000\000\001"]
  and
["ensemble.local", [], 30, "\376\200\000\004\000\000\000\000\002\003\223\377\376\255\010\214", "\300\250{\232" ]

Similar information can be returned by Socket.getaddrinfo if called as:

Socket.getaddrinfo(+host+, 0, Socket::AF_UNSPEC, Socket::SOCK_STREAM, nil, Socket::AI_CANONNAME)

Examples

Socket.gethostbyname "example.com"                                                           
=> ["example.com", [], 2, "\300\000\"\246"]

This name has no DNS aliases, and a single IPv4 address.

Socket.gethostbyname "smtp.telus.net"
=> ["smtp.svc.telus.net", ["smtp.telus.net"], 2, "\307\271\334\371"]

This name is an an alias so the canonical name is returned, as well as the alias and a single IPv4 address.

Socket.gethostbyname "localhost"
=> ["localhost", [], 30, "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\001", "\177\000\000\001"]

This machine has no aliases, returns an IPv6 address, and has an additional IPv4 address.

host can also be an IP address in presentation format, in which case a reverse lookup is done on the address:

Socket.gethostbyname("127.0.0.1")
=> ["localhost", [], 2, "\177\000\000\001"]

Socket.gethostbyname("192.0.34.166")
=> ["www.example.com", [], 2, "\300\000\"\246"]

See

See: Socket.getaddrinfo

 
               static VALUE
tcp_s_gethostbyname(obj, host)
    VALUE obj, host;
{
    rb_secure(3);
    return make_hostent(host, sock_addrinfo(host, Qnil, SOCK_STREAM, AI_CANONNAME), tcp_sockaddr);
}
            
new(remote_host, remote_port, local_host=nil, local_port=nil) click to toggle source

Opens a TCP connection to remote_host on remote_port. If local_host and local_port are specified, then those parameters are used on the local end to establish the connection.

 
               static VALUE
tcp_init(argc, argv, sock)
     int argc;
     VALUE *argv;
     VALUE sock;
{
    VALUE remote_host, remote_serv;
    VALUE local_host, local_serv;

    rb_scan_args(argc, argv, "22", &remote_host, &remote_serv,
                        &local_host, &local_serv);

    return init_inetsock(sock, remote_host, remote_serv,
                        local_host, local_serv, INET_CLIENT);
}
            

Commenting is here to help enhance the documentation. For example, code samples, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

If you want to help improve the Ruby documentation, please visit Documenting-ruby.org.

blog comments powered by Disqus