class TCPSocket - Documentation for Ruby 3.2

# class TCPSocket

`TCPSocket` represents a TCP/IP client socket.

A simple client may look like:

    require 'socket'

    s = TCPSocket.new 'localhost', 2000

    while line = s.gets # Read lines from socket
      puts line         # and print them
    end

    s.close             # close socket when done

### Public Class Methods

gethostbyname(hostname) → [official_hostname, alias_hostnames, address_family, *address_list] click to toggle source

Use `Addrinfo.getaddrinfo` instead. This method is deprecated for the following reasons:

- The 3rd element of the result is the address family of the first address. The address families of the rest of the addresses are not returned.

- gethostbyname() 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 lookups host information by hostname.

    TCPSocket.gethostbyname("localhost")
    #=> ["localhost", ["hal"], 2, "127.0.0.1"]

    static VALUE
    tcp_s_gethostbyname(VALUE obj, VALUE host)
    {
        rb_warn("TCPSocket.gethostbyname is deprecated; use Addrinfo.getaddrinfo instead.");
        struct rb_addrinfo *res =
            rsock_addrinfo(host, Qnil, AF_UNSPEC, SOCK_STREAM, AI_CANONNAME);
        return rsock_make_hostent(host, res, tcp_sockaddr);
    }

new(remote_host, remote_port, local_host=nil, local_port=nil, connect_timeout: 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.

:connect_timeout

  specify the timeout in seconds.

    static VALUE
    tcp_init(int argc, VALUE *argv, VALUE sock)
    {
        VALUE remote_host, remote_serv;
        VALUE local_host, local_serv;
        VALUE opt;
        static ID keyword_ids[2];
        VALUE kwargs[2];
        VALUE resolv_timeout = Qnil;
        VALUE connect_timeout = Qnil;

        if (!keyword_ids[0]) {
            CONST_ID(keyword_ids[0], "resolv_timeout");
            CONST_ID(keyword_ids[1], "connect_timeout");
        }

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

        if (!NIL_P(opt)) {
            rb_get_kwargs(opt, keyword_ids, 0, 2, kwargs);
            if (kwargs[0] != Qundef) { resolv_timeout = kwargs[0]; }
            if (kwargs[1] != Qundef) { connect_timeout = kwargs[1]; }
        }

        return rsock_init_inetsock(sock, remote_host, remote_serv,
                                   local_host, local_serv, INET_CLIENT,
                                   resolv_timeout, connect_timeout);
    }

new(host, serv, *rest) click to toggle source

    # File lib/resolv-replace.rb, line 23
    def initialize(host, serv, *rest)
      rest[0] = IPSocket.getaddress(rest[0]) if rest[0]
      original_resolv_initialize(IPSocket.getaddress(host), serv, *rest)
    end