Class: TCPSocket

Inherits:
IPSocket show all
Defined in:
tcpsocket.c,
tcpsocket.c

Overview

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

Direct Known Subclasses

SOCKSSocket, TCPServer

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from IPSocket

#addr, getaddress, #inspect, #peeraddr, #recvfrom

Methods inherited from BasicSocket

#close_read, #close_write, #connect_address, do_not_reverse_lookup, #do_not_reverse_lookup, do_not_reverse_lookup=, #do_not_reverse_lookup=, for_fd, #getpeereid, #getpeername, #getsockname, #getsockopt, #local_address, #read_nonblock, #recv, #recv_nonblock, #recvmsg, #recvmsg_nonblock, #remote_address, #send, #sendmsg, #sendmsg_nonblock, #setsockopt, #shutdown, #write_nonblock

Constructor Details

#new(remote_host, remote_port, local_host = nil, local_port = nil, resolv_timeout: nil, connect_timeout: nil, fast_fallback: true) ⇒ Object

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.

Starting from Ruby 3.4, this method operates according to the Happy Eyeballs Version 2 (RFC 8305) algorithm by default, except on Windows.

For details on Happy Eyeballs Version 2, see Socket.tcp_fast_fallback=.

To make it behave the same as in Ruby 3.3 and earlier, explicitly specify the option fast_fallback:false. Or, setting Socket.tcp_fast_fallback=false will disable Happy Eyeballs Version 2 not only for this method but for all Socket globally.

When using TCPSocket.new on Windows, Happy Eyeballs Version 2 is not provided, and it behaves the same as in Ruby 3.3 and earlier.

:resolv_timeout

Specifies the timeout in seconds from when the hostname resolution starts.

:connect_timeout

This method sequentially attempts connecting to all candidate destination addresses.
The connect_timeout specifies the timeout in seconds from the start of the connection attempt to the last candidate.
By default, all connection attempts continue until the timeout occurs.
When fast_fallback:false is explicitly specified,
a timeout is set for each connection attempt and any connection attempt that exceeds its timeout will be canceled.

:fast_fallback

Enables the Happy Eyeballs Version 2 algorithm (enabled by default).


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# File 'tcpsocket.c', line 40

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[4];
    VALUE kwargs[4];
    VALUE resolv_timeout = Qnil;
    VALUE connect_timeout = Qnil;
    VALUE fast_fallback = Qnil;
    VALUE test_mode_settings = Qnil;

    if (!keyword_ids[0]) {
        CONST_ID(keyword_ids[0], "resolv_timeout");
        CONST_ID(keyword_ids[1], "connect_timeout");
        CONST_ID(keyword_ids[2], "fast_fallback");
        CONST_ID(keyword_ids[3], "test_mode_settings");
    }

    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, 4, kwargs);
        if (kwargs[0] != Qundef) { resolv_timeout = kwargs[0]; }
        if (kwargs[1] != Qundef) { connect_timeout = kwargs[1]; }
        if (kwargs[2] != Qundef) { fast_fallback = kwargs[2]; }
        if (kwargs[3] != Qundef) { test_mode_settings = kwargs[3]; }
    }

    if (fast_fallback == Qnil) {
        fast_fallback = rb_ivar_get(rb_cSocket, tcp_fast_fallback);
        if (fast_fallback == Qnil) fast_fallback = Qtrue;
    }

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

Class Method Details

.gethostbyname(hostname) ⇒ Array

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"]

Returns:

  • (Array) 

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# File 'tcpsocket.c', line 107

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);
}