Socket - node__dgram.d.ts - Node

class Socket

extends EventEmitter

Usage in Deno

```typescript import { Socket } from "node:node__dgram.d.ts"; ```

> [!WARNING] Deno compatibility > The following methods are non-functional stubs: > - addMembership > - addSourceSpecificMembership > - dropMembership > - dropSourceSpecificMembership > - setBroadcast > - setMulticastInterface > - setMulticastLoopback > - setMulticastTtl > - setTtl > Encapsulates the datagram functionality. New instances of `dgram.Socket` are created using [createSocket](../.././node__dgram.d.ts/~/createSocket). The `new` keyword is not to be used to create `dgram.Socket` instances.

Methods



[Symbol.asyncDispose](): Promise<void>

Calls `socket.close()` and returns a promise that fulfills when the socket has closed.



addListener(event: string,
listener: (...args: any[]) => void,
): this

events.EventEmitter 1. close 2. connect 3. error 4. listening 5. message



addListener(event: "close",
listener: () => void,
): this



addListener(event: "connect",
listener: () => void,
): this



addListener(event: "error",
listener: (err: Error) => void,
): this



addListener(event: "listening",
listener: () => void,
): this



addListener(event: "message",
listener: (msg: Buffer,
rinfo: RemoteInfo,
) => void,
): this



addMembership(multicastAddress: string,
multicastInterface?: string,
): void

Tells the kernel to join a multicast group at the given `multicastAddress` and `multicastInterface` using the `IP_ADD_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 `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: ```js import cluster from 'node:cluster'; import dgram from 'node: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'); }); } ```



addSourceSpecificMembership(sourceAddress: string,
groupAddress: string,
multicastInterface?: string,
): void

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.



address(): AddressInfo

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.



bind(port?: number,
address?: string,
callback?: () => void,
): this

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: ```js import dgram from 'node:dgram'; const server = dgram.createSocket('udp4'); server.on('error', (err) => { console.error(`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 ```



bind(port?: number,
callback?: () => void,
): this



bind(callback?: () => void): this



bind(options: BindOptions,
callback?: () => void,
): this



close(callback?: () => void): this

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.



connect(port: number,
address?: string,
callback?: () => void,
): void

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.



connect(port: number,
callback: () => void,
): void



disconnect(): void

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.



dropMembership(multicastAddress: string,
multicastInterface?: string,
): void

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.



dropSourceSpecificMembership(sourceAddress: string,
groupAddress: string,
multicastInterface?: string,
): void

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.



emit(event: string | symbol,
...args: any[],
): boolean



emit(event: "close"): boolean



emit(event: "connect"): boolean



emit(event: "error",
err: Error,
): boolean



emit(event: "listening"): boolean



emit(event: "message",
msg: Buffer,
rinfo: RemoteInfo,
): boolean



getRecvBufferSize(): number

This method throws `ERR_SOCKET_BUFFER_SIZE` if called on an unbound socket.



getSendBufferSize(): number

This method throws `ERR_SOCKET_BUFFER_SIZE` if called on an unbound socket.



getSendQueueCount(): number



getSendQueueSize(): number



on(event: string,
listener: (...args: any[]) => void,
): this



on(event: "close",
listener: () => void,
): this



on(event: "connect",
listener: () => void,
): this



on(event: "error",
listener: (err: Error) => void,
): this



on(event: "listening",
listener: () => void,
): this



on(event: "message",
listener: (msg: Buffer,
rinfo: RemoteInfo,
) => void,
): this



once(event: string,
listener: (...args: any[]) => void,
): this



once(event: "close",
listener: () => void,
): this



once(event: "connect",
listener: () => void,
): this



once(event: "error",
listener: (err: Error) => void,
): this



once(event: "listening",
listener: () => void,
): this



once(event: "message",
listener: (msg: Buffer,
rinfo: RemoteInfo,
) => void,
): this



prependListener(event: string,
listener: (...args: any[]) => void,
): this



prependListener(event: "close",
listener: () => void,
): this



prependListener(event: "connect",
listener: () => void,
): this



prependListener(event: "error",
listener: (err: Error) => void,
): this



prependListener(event: "listening",
listener: () => void,
): this



prependListener(event: "message",
listener: (msg: Buffer,
rinfo: RemoteInfo,
) => void,
): this



prependOnceListener(event: string,
listener: (...args: any[]) => void,
): this



prependOnceListener(event: "close",
listener: () => void,
): this



prependOnceListener(event: "connect",
listener: () => void,
): this



prependOnceListener(event: "error",
listener: (err: Error) => void,
): this



prependOnceListener(event: "listening",
listener: () => void,
): this



prependOnceListener(event: "message",
listener: (msg: Buffer,
rinfo: RemoteInfo,
) => void,
): this



ref(): this

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.



remoteAddress(): AddressInfo

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.



send(msg: string
 | Uint8Array
 | readonly any[],
port?: number,
address?: string,
callback?: (error: Error | null,
bytes: number,
) => void,
): void

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`; ```js import dgram from 'node:dgram'; import { Buffer } from 'node: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`; ```js import dgram from 'node:dgram'; import { Buffer } from 'node: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`: ```js import dgram from 'node:dgram'; import { Buffer } from 'node:buffer'; const message = Buffer.from('Some bytes'); const client = dgram.createSocket('udp4'); client.connect(41234, 'localhost', (err) => { client.send(message, (err) => { client.close(); }); }); ```



send(msg: string
 | Uint8Array
 | readonly any[],
port?: number,
callback?: (error: Error | null,
bytes: number,
) => void,
): void



send(msg: string
 | Uint8Array
 | readonly any[],
callback?: (error: Error | null,
bytes: number,
) => void,
): void



send(msg: string | Uint8Array,
offset: number,
length: number,
port?: number,
address?: string,
callback?: (error: Error | null,
bytes: number,
) => void,
): void



send(msg: string | Uint8Array,
offset: number,
length: number,
port?: number,
callback?: (error: Error | null,
bytes: number,
) => void,
): void



send(msg: string | Uint8Array,
offset: number,
length: number,
callback?: (error: Error | null,
bytes: number,
) => void,
): void



setBroadcast(flag: boolean): void

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.



setMulticastInterface(multicastInterface: string): void

_All references to scope in this section are referring to [IPv6 Zone Indices](https://en.wikipedia.org/wiki/IPv6_address#Scoped_literal_IPv6_addresses), which are defined by [RFC 4007](https://tools.ietf.org/html/rfc4007). 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: ```js const socket = dgram.createSocket('udp6'); socket.bind(1234, () => { socket.setMulticastInterface('::%eth1'); }); ``` On Windows, where scope format uses an interface number: ```js 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: ```js const socket = dgram.createSocket('udp4'); socket.bind(1234, () => { socket.setMulticastInterface('10.0.0.2'); }); ```



setMulticastLoopback(flag: boolean): boolean

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.



setMulticastTTL(ttl: number): number

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.



setRecvBufferSize(size: number): void

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.



setSendBufferSize(size: number): void

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.



setTTL(ttl: number): number

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 1 and 255\. The default on most systems is 64. This method throws `EBADF` if called on an unbound socket.



unref(): this

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 additional effect. The `socket.unref()` method returns a reference to the socket so calls can be chained.