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Class: UDPSocket

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::IPSocket, ::BasicSocket, ::IO
Instance Chain:
self, ::IPSocket, ::BasicSocket, ::IO
Inherits: IPSocket
Defined in: ext/socket/udpsocket.c

Overview

UDPSocket represents a UDP/IP socket.

Class Attribute Summary

::BasicSocket - Inherited

.do_not_reverse_lookup

Gets the global do_not_reverse_lookup flag.
.do_not_reverse_lookup=

Sets the global do_not_reverse_lookup flag.

Class Method Summary

::IPSocket - Inherited

.getaddress

Lookups the IP address of host.

::BasicSocket - Inherited

.for_fd

Returns a socket object which contains the file descriptor, fd.

Instance Attribute Summary

::BasicSocket - Inherited

#do_not_reverse_lookup

Gets the do_not_reverse_lookup flag of basicsocket.
#do_not_reverse_lookup=

Sets the do_not_reverse_lookup flag of basicsocket.

Instance Method Summary

::IPSocket - Inherited

#addr

Returns the local address as an array which contains address_family, port, hostname and numeric_address.
#peeraddr

Returns the remote address as an array which contains address_family, port, hostname and numeric_address.
#recvfrom

Receives a message and return the message as a string and an address which the message come from.

::BasicSocket - Inherited

#close_read

Disallows further read using shutdown system call.
#close_write

Disallows further write using shutdown system call.
#connect_address

Returns an address of the socket suitable for connect in the local machine.
#getpeereid

Returns the user and group on the peer of the UNIX socket.
#getpeername

Returns the remote address of the socket as a sockaddr string.
#getsockname

Returns the local address of the socket as a sockaddr string.
#getsockopt

Gets a socket option.
#local_address

Returns an ::Addrinfo object for local address obtained by getsockname.
#recv

Receives a message.
#recv_nonblock

Receives up to maxlen bytes from socket using recvfrom(2) after O_NONBLOCK is set for the underlying file descriptor.
#recvmsg

recvmsg receives a message using recvmsg(2) system call in blocking manner.
#recvmsg_nonblock

recvmsg receives a message using recvmsg(2) system call in non-blocking manner.
#remote_address

Returns an ::Addrinfo object for remote address obtained by getpeername.
#send

send mesg via basicsocket.
#sendmsg

sendmsg sends a message using sendmsg(2) system call in blocking manner.
#sendmsg_nonblock

sendmsg_nonblock sends a message using sendmsg(2) system call in non-blocking manner.
#setsockopt

Sets a socket option.
#shutdown

Calls shutdown(2) system call.

Constructor Details

.new([address_family]) ⇒ socket

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>

Instance Method Details

#bind(host, port) # = > 0))

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"]]

#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"]]

#recvfrom_nonblock(maxlen) ⇒ Array, sender_inet_addr #recvfrom_nonblock(maxlen, flags) ⇒ Array, 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

#send(mesg, flags, host, port) ⇒ numbytes_sent #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"