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);
}