Class: UDPSocket

Inherits:
IPSocket show all
Defined in:
udpsocket.c,
udpsocket.c,
lib/socket.rb

Overview

UDPSocket represents a UDP/IP socket.

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, #sendmsg, #sendmsg_nonblock, #setsockopt, #shutdown, #write_nonblock

Constructor Details

#new([address_family]) ⇒ Object

Creates a new UDPSocket object.

address_family should be an integer, a string or a symbol: Socket::AF_INET, “AF_INET”, :INET, etc.

require 'socket'

UDPSocket.new                   #=> #<UDPSocket:fd 3>
UDPSocket.new(Socket::AF_INET6) #=> #<UDPSocket:fd 4>



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# File 'udpsocket.c', line 28

static VALUE
udp_init(int argc, VALUE *argv, VALUE sock)
{
    VALUE arg;
    int family = AF_INET;
    int fd;

    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
	family = rsock_family_arg(arg);
    }
    fd = rsock_socket(family, SOCK_DGRAM, 0);
    if (fd < 0) {
	rb_sys_fail("socket(2) - udp");
    }

    return rsock_init_sock(sock, fd);
}

Instance Method Details

#bind(host, port) ⇒ Object

Binds udpsocket to host:port.

u1 = UDPSocket.new
u1.bind("127.0.0.1", 4913)
u1.send "message-to-self", 0, "127.0.0.1", 4913
p u1.recvfrom(10) #=> ["message-to", ["AF_INET", 4913, "localhost", "127.0.0.1"]]



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# File 'udpsocket.c', line 131

static VALUE
udp_bind(VALUE sock, VALUE host, VALUE port)
{
    struct udp_arg arg;
    VALUE ret;

    GetOpenFile(sock, arg.fptr);
    arg.res = rsock_addrinfo(host, port, rsock_fd_family(arg.fptr->fd), SOCK_DGRAM, 0);
    ret = rb_ensure(udp_bind_internal, (VALUE)&arg,
		    rsock_freeaddrinfo, (VALUE)arg.res);
    if (!ret) rsock_sys_fail_host_port("bind(2)", host, port);
    return INT2FIX(0);
}

#connect(host, port) ⇒ 0

Connects udpsocket to host:port.

This makes possible to send without destination address.

u1 = UDPSocket.new
u1.bind("127.0.0.1", 4913)
u2 = UDPSocket.new
u2.connect("127.0.0.1", 4913)
u2.send "uuuu", 0
p u1.recvfrom(10) #=> ["uuuu", ["AF_INET", 33230, "localhost", "127.0.0.1"]]

Returns:

  • (0) 


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# File 'udpsocket.c', line 86

static VALUE
udp_connect(VALUE sock, VALUE host, VALUE port)
{
    struct udp_arg arg;
    VALUE ret;

    GetOpenFile(sock, arg.fptr);
    arg.res = rsock_addrinfo(host, port, rsock_fd_family(arg.fptr->fd), SOCK_DGRAM, 0);
    ret = rb_ensure(udp_connect_internal, (VALUE)&arg,
		    rsock_freeaddrinfo, (VALUE)arg.res);
    if (!ret) rsock_sys_fail_host_port("connect(2)", host, port);
    return INT2FIX(0);
}

#recvfrom_nonblock(len, flag = 0, outbuf = nil, exception: true) ⇒ Object

call-seq:

udpsocket.recvfrom_nonblock(maxlen [, flags[, outbuf [, options]]]) => [mesg, sender_inet_addr]

Receives up to maxlen bytes from udpsocket using recvfrom(2) after O_NONBLOCK is set for the underlying file descriptor. flags is zero or more of the MSG_ options. The first element of the results, mesg, is the data received. The second element, sender_inet_addr, is an array to represent the sender address.

When recvfrom(2) returns 0, Socket#recvfrom_nonblock returns an empty string as data. It means an empty packet.

Parameters

  • maxlen - the number of bytes to receive from the socket

  • flags - zero or more of the MSG_ options

  • outbuf - destination String buffer

  • options - keyword hash, supporting ‘exception: false`

Example

require ‘socket’ s1 = UDPSocket.new s1.bind(“127.0.0.1”, 0) s2 = UDPSocket.new s2.bind(“127.0.0.1”, 0) s2.connect(*s1.addr.values_at(3,1)) s1.connect(*s2.addr.values_at(3,1)) s1.send “aaa”, 0 begin # emulate blocking recvfrom p s2.recvfrom_nonblock(10) #=> [“aaa”, [“AF_INET”, 33302, “localhost.localdomain”, “127.0.0.1”]] rescue IO::WaitReadable IO.select() retry end

Refer to Socket#recvfrom for the exceptions that may be thrown if the call to recvfrom_nonblock fails.

UDPSocket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure, including Errno::EWOULDBLOCK.

If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, it is extended by IO::WaitReadable. So IO::WaitReadable can be used to rescue the exceptions for retrying recvfrom_nonblock.

By specifying a keyword argument exception to false, you can indicate that recvfrom_nonblock should not raise an IO::WaitReadable exception, but return the symbol :wait_readable instead.

See

  • Socket#recvfrom



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# File 'lib/socket.rb', line 1271

def recvfrom_nonblock(len, flag = 0, outbuf = nil, exception: true)
  __recvfrom_nonblock(len, flag, outbuf, exception)
end

#send(mesg, flags, host, port) ⇒ Object #send(mesg, flags, sockaddr_to) ⇒ Object #send(mesg, flags) ⇒ Object

Sends mesg via udpsocket.

flags should be a bitwise OR of Socket::MSG_* constants.

u1 = UDPSocket.new
u1.bind("127.0.0.1", 4913)

u2 = UDPSocket.new
u2.send "hi", 0, "127.0.0.1", 4913

mesg, addr = u1.recvfrom(10)
u1.send mesg, 0, addr[3], addr[1]

p u2.recv(100) #=> "hi"



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# File 'udpsocket.c', line 199

static VALUE
udp_send(int argc, VALUE *argv, VALUE sock)
{
    VALUE flags, host, port;
    struct udp_send_arg arg;
    VALUE ret;

    if (argc == 2 || argc == 3) {
	return rsock_bsock_send(argc, argv, sock);
    }
    rb_scan_args(argc, argv, "4", &arg.sarg.mesg, &flags, &host, &port);

    StringValue(arg.sarg.mesg);
    GetOpenFile(sock, arg.fptr);
    arg.sarg.fd = arg.fptr->fd;
    arg.sarg.flags = NUM2INT(flags);
    arg.res = rsock_addrinfo(host, port, rsock_fd_family(arg.fptr->fd), SOCK_DGRAM, 0);
    ret = rb_ensure(udp_send_internal, (VALUE)&arg,
		    rsock_freeaddrinfo, (VALUE)arg.res);
    if (!ret) rsock_sys_fail_host_port("sendto(2)", host, port);
    return ret;
}