import { Socket } from "https://deno.land/std@0.145.0/node/dgram.ts";
Encapsulates the datagram functionality.
New instances of dgram.Socket
are created using createSocket
.
The new
keyword is not to be used to create dgram.Socket
instances.
Constructors
Methods
Tells the kernel to join a multicast group at the given multicastAddress
and multicastInterface
using the IP_ADD_MEMBERSHIP
socket option. If
themulticastInterface
argument is not specified, the operating system
will choose one interface and will add membership to it. To add membership
to every available interface, call addMembership
multiple times, once
per interface.
When called on an unbound socket, this method will implicitly bind to a random port, listening on all interfaces.
When sharing a UDP socket across multiple cluster
workers, the
socket.addMembership()
function must be called only once or an
EADDRINUSE
error will occur:
import cluster from 'cluster';
import dgram from 'dgram';
if (cluster.isPrimary) {
cluster.fork(); // Works ok.
cluster.fork(); // Fails with EADDRINUSE.
} else {
const s = dgram.createSocket('udp4');
s.bind(1234, () => {
s.addMembership('224.0.0.114');
});
}
Returns an object containing the address information for a socket.
For UDP sockets, this object will contain address
, family
and port
properties.
This method throws EBADF
if called on an unbound socket.
Tells the kernel to join a source-specific multicast channel at the given
sourceAddress
and groupAddress
, using the multicastInterface
with
the IP_ADD_SOURCE_MEMBERSHIP
socket option. If the multicastInterface
argument is not specified, the operating system will choose one interface
and will add membership to it. To add membership to every available
interface, call socket.addSourceSpecificMembership()
multiple times,
once per interface.
When called on an unbound socket, this method will implicitly bind to a random port, listening on all interfaces.
For UDP sockets, causes the dgram.Socket
to listen for datagram
messages on a named port
and optional address
. If port
is not
specified or is 0
, the operating system will attempt to bind to a
random port. If address
is not specified, the operating system will
attempt to listen on all addresses. Once binding is complete, a
'listening'
event is emitted and the optional callback
function is
called.
Specifying both a 'listening'
event listener and passing a callback
to
the socket.bind()
method is not harmful but not very useful.
A bound datagram socket keeps the Node.js process running to receive datagram messages.
If binding fails, an 'error'
event is generated. In rare case (e.g.
attempting to bind with a closed socket), an Error
may be thrown.
Example of a UDP server listening on port 41234:
import dgram from 'dgram';
const server = dgram.createSocket('udp4');
server.on('error', (err) => {
console.log(`server error:\n${err.stack}`);
server.close();
});
server.on('message', (msg, rinfo) => {
console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`);
});
server.on('listening', () => {
const address = server.address();
console.log(`server listening ${address.address}:${address.port}`);
});
server.bind(41234);
// Prints: server listening 0.0.0.0:41234
Close the underlying socket and stop listening for data on it. If a
callback is provided, it is added as a listener for the 'close'
event.
Associates the dgram.Socket
to a remote address and port. Every
message sent by this handle is automatically sent to that destination.
Also, the socket will only receive messages from that remote peer.
Trying to call connect()
on an already connected socket will result
in an ERR_SOCKET_DGRAM_IS_CONNECTED
exception. If address
is not
provided, '127.0.0.1'
(for udp4
sockets) or '::1'
(for udp6
sockets)
will be used by default. Once the connection is complete, a 'connect'
event
is emitted and the optional callback
function is called. In case of failure,
the callback
is called or, failing this, an 'error'
event is emitted.
A synchronous function that disassociates a connected dgram.Socket
from
its remote address. Trying to call disconnect()
on an unbound or already
disconnected socket will result in an ERR_SOCKET_DGRAM_NOT_CONNECTED
exception.
Instructs the kernel to leave a multicast group at multicastAddress
using the IP_DROP_MEMBERSHIP
socket option. This method is automatically
called by the kernel when the socket is closed or the process terminates,
so most apps will never have reason to call this.
If multicastInterface
is not specified, the operating system will
attempt to drop membership on all valid interfaces.
Instructs the kernel to leave a source-specific multicast channel at the
given sourceAddress
and groupAddress
using the
IP_DROP_SOURCE_MEMBERSHIP
socket option. This method is automatically
called by the kernel when the socket is closed or the process terminates,
so most apps will never have reason to call this.
If multicastInterface
is not specified, the operating system will
attempt to drop membership on all valid interfaces.
This method throws ERR_SOCKET_BUFFER_SIZE
if called on an unbound
socket.
This method throws ERR_SOCKET_BUFFER_SIZE
if called on an unbound
socket.
By default, binding a socket will cause it to block the Node.js process
from exiting as long as the socket is open. The socket.unref()
method
can be used to exclude the socket from the reference counting that keeps
the Node.js process active. The socket.ref()
method adds the socket back
to the reference counting and restores the default behavior.
Calling socket.ref()
multiples times will have no additional effect.
The socket.ref()
method returns a reference to the socket so calls can
be chained.
Returns an object containing the address
, family
, and port
of the
remote endpoint. This method throws an ERR_SOCKET_DGRAM_NOT_CONNECTED
exception if the socket is not connected.
Broadcasts a datagram on the socket.
For connectionless sockets, the destination port
and address
must be
specified. Connected sockets, on the other hand, will use their associated
remote endpoint, so the port
and address
arguments must not be set.
The msg
argument contains the message to be sent.
Depending on its type, different behavior can apply. If msg
is a
Buffer
, any TypedArray
or a DataView
,
the offset
and length
specify the offset within the Buffer
where the
message begins and the number of bytes in the message, respectively.
If msg
is a String
, then it is automatically converted to a Buffer
with 'utf8'
encoding. With messages that contain multi-byte characters,
offset
and length
will be calculated with respect to byte length
and
not the character position. If msg
is an array, offset
and length
must not be specified.
The address
argument is a string. If the value of address
is a host
name, DNS will be used to resolve the address of the host. If address
is not provided or otherwise nullish, '127.0.0.1'
(for udp4
sockets)
or '::1'
(for udp6
sockets) will be used by default.
If the socket has not been previously bound with a call to bind
, the
socket is assigned a random port number and is bound to the "all
interfaces" address ('0.0.0.0'
for udp4
sockets, '::0'
for udp6
sockets.)
An optional callback
function may be specified to as a way of
reporting DNS errors or for determining when it is safe to reuse the buf
object. DNS lookups delay the time to send for at least one tick of the
Node.js event loop.
The only way to know for sure that the datagram has been sent is by using
a callback
. If an error occurs and a callback
is given, the error will
be passed as the first argument to the callback
. If a callback
is not
given, the error is emitted as an 'error'
event on the socket
object.
Offset and length are optional but both must be set if either are used.
They are supported only when the first argument is a Buffer
, a
TypedArray
, or a DataView
.
This method throws ERR_SOCKET_BAD_PORT
if called on an unbound socket.
Example of sending a UDP packet to a port on localhost
;
import dgram from 'dgram';
import { Buffer } from 'buffer';
const message = Buffer.from('Some bytes');
const client = dgram.createSocket('udp4');
client.send(message, 41234, 'localhost', (err) => {
client.close();
});
Example of sending a UDP packet composed of multiple buffers to a port on
127.0.0.1
;
import dgram from 'dgram';
import { Buffer } from 'buffer';
const buf1 = Buffer.from('Some ');
const buf2 = Buffer.from('bytes');
const client = dgram.createSocket('udp4');
client.send([buf1, buf2], 41234, (err) => {
client.close();
});
Sending multiple buffers might be faster or slower depending on the application and operating system. Run benchmarks to determine the optimal strategy on a case-by-case basis. Generally speaking, however, sending multiple buffers is faster.
Example of sending a UDP packet using a socket connected to a port on
localhost
:
import dgram from 'dgram';
import { Buffer } from 'buffer';
const message = Buffer.from('Some bytes');
const client = dgram.createSocket('udp4');
client.connect(41234, 'localhost', (err) => {
client.send(message, (err) => {
client.close();
});
});
Sets or clears the SO_BROADCAST
socket option. When set to true
, UDP
packets may be sent to a local interface's broadcast address.
This method throws EBADF
if called on an unbound socket.
All references to scope in this section are referring to IPv6 Zone Indices, which are defined by RFC
4007. In string form, an IP
with a scope index is written as 'IP%scope'
where scope is an interface name
or interface number.
Sets the default outgoing multicast interface of the socket to a chosen
interface or back to system interface selection. The multicastInterface
must
be a valid string representation of an IP from the socket's family.
For IPv4 sockets, this should be the IP configured for the desired physical interface. All packets sent to multicast on the socket will be sent on the interface determined by the most recent successful use of this call.
For IPv6 sockets, multicastInterface
should include a scope to indicate the
interface as in the examples that follow. In IPv6, individual send
calls can
also use explicit scope in addresses, so only packets sent to a multicast
address without specifying an explicit scope are affected by the most recent
successful use of this call.
This method throws EBADF
if called on an unbound socket.
Example: IPv6 outgoing multicast interface
On most systems, where scope format uses the interface name:
const socket = dgram.createSocket('udp6');
socket.bind(1234, () => {
socket.setMulticastInterface('::%eth1');
});
On Windows, where scope format uses an interface number:
const socket = dgram.createSocket('udp6');
socket.bind(1234, () => {
socket.setMulticastInterface('::%2');
});
Example: IPv4 outgoing multicast interface
All systems use an IP of the host on the desired physical interface:
const socket = dgram.createSocket('udp4');
socket.bind(1234, () => {
socket.setMulticastInterface('10.0.0.2');
});
Sets or clears the IP_MULTICAST_LOOP
socket option. When set to true
,
multicast packets will also be received on the local interface.
This method throws EBADF
if called on an unbound socket.
Sets the IP_MULTICAST_TTL
socket option. While TTL generally stands for
"Time to Live", in this context it specifies the number of IP hops that a
packet is allowed to travel through, specifically for multicast traffic. Each
router or gateway that forwards a packet decrements the TTL. If the TTL is
decremented to 0 by a router, it will not be forwarded.
The ttl
argument may be between 0 and 255. The default on most systems is 1
.
This method throws EBADF
if called on an unbound socket.
Sets the SO_RCVBUF
socket option. Sets the maximum socket receive buffer
in bytes.
This method throws ERR_SOCKET_BUFFER_SIZE
if called on an unbound socket.
Sets the SO_SNDBUF
socket option. Sets the maximum socket send buffer
in bytes.
This method throws ERR_SOCKET_BUFFER_SIZE
if called on an unbound socket.
Sets the IP_TTL
socket option. While TTL generally stands for "Time to Live",
in this context it specifies the number of IP hops that a packet is allowed to
travel through. Each router or gateway that forwards a packet decrements the
TTL. If the TTL is decremented to 0 by a router, it will not be forwarded.
Changing TTL values is typically done for network probes or when multicasting.
The ttl
argument may be between between 1 and 255. The default on most systems
is 64.
This method throws EBADF
if called on an unbound socket.
By default, binding a socket will cause it to block the Node.js process from
exiting as long as the socket is open. The socket.unref()
method can be used
to exclude the socket from the reference counting that keeps the Node.js
process active, allowing the process to exit even if the socket is still
listening.
Calling socket.unref()
multiple times will have no addition effect.
The socket.unref()
method returns a reference to the socket so calls can be
chained.