Extended maintenance of Ruby 1.9.3 ended on February 23, 2015. Read more

In Files

  • socket/udpsocket.c

UDPSocket

UDPSocket represents a UDP/IP socket.

Public Class Methods

new([address_family]) => socket click to toggle source

Creates a new UDPSocket object.

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

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

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

    rb_secure(3);
    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);
}

Public Instance Methods

bind(host, port) #=> 0 click to toggle source

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"]]

 
               static VALUE
udp_bind(VALUE sock, VALUE host, VALUE port)
{
    rb_io_t *fptr;
    struct addrinfo *res0, *res;

    rb_secure(3);
    res0 = rsock_addrinfo(host, port, SOCK_DGRAM, 0);
    GetOpenFile(sock, fptr);
    for (res = res0; res; res = res->ai_next) {
        if (bind(fptr->fd, res->ai_addr, res->ai_addrlen) < 0) {
            continue;
        }
        freeaddrinfo(res0);
        return INT2FIX(0);
    }
    freeaddrinfo(res0);
    rb_sys_fail("bind(2)");
    return INT2FIX(0);
}
connect(host, port) => 0 click to toggle source

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"]]

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

    rb_secure(3);
    arg.res = rsock_addrinfo(host, port, SOCK_DGRAM, 0);
    GetOpenFile(sock, fptr);
    arg.fd = fptr->fd;
    ret = rb_ensure(udp_connect_internal, (VALUE)&arg,
                    rsock_freeaddrinfo, (VALUE)arg.res);
    if (!ret) rb_sys_fail("connect(2)");
    return INT2FIX(0);
}
recvfrom_nonblock(maxlen) => [mesg, sender_inet_addr] click to toggle source
recvfrom_nonblock(maxlen, flags) => [mesg, sender_inet_addr]

Receives up to maxlen bytes from udpsocket using recvfrom(2) after O_NONBLOCK is set for the underlying file descriptor. If maxlen is omitted, its default value is 65536. 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

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([s2])
  retry
end

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

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

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

See ↑

 
               static VALUE
udp_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return rsock_s_recvfrom_nonblock(sock, argc, argv, RECV_IP);
}
send(mesg, flags, host, port) => numbytes_sent click to toggle source
send(mesg, flags, sockaddr_to) => numbytes_sent
send(mesg, flags) => numbytes_sent

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"

 
               static VALUE
udp_send(int argc, VALUE *argv, VALUE sock)
{
    VALUE flags, host, port;
    rb_io_t *fptr;
    int n;
    struct addrinfo *res0, *res;
    struct rsock_send_arg arg;

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

    StringValue(arg.mesg);
    res0 = rsock_addrinfo(host, port, SOCK_DGRAM, 0);
    GetOpenFile(sock, fptr);
    arg.fd = fptr->fd;
    arg.flags = NUM2INT(flags);
    for (res = res0; res; res = res->ai_next) {
      retry:
        arg.to = res->ai_addr;
        arg.tolen = res->ai_addrlen;
        rb_thread_fd_writable(arg.fd);
        n = (int)BLOCKING_REGION_FD(rsock_sendto_blocking, &arg);
        if (n >= 0) {
            freeaddrinfo(res0);
            return INT2FIX(n);
        }
        if (rb_io_wait_writable(fptr->fd)) {
            goto retry;
        }
    }
    freeaddrinfo(res0);
    rb_sys_fail("sendto(2)");
    return INT2FIX(n);
}

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.