Socket Module

The socket module provides functions for interacting with sockets.

Functions can be individually imported and directly accessed using the named import syntax:

import { AF_INET, SOCK_STREAM, create as socket } from 'socket';

let sock = socket(AF_INET, SOCK_STREAM, 0);
sock.connect('192.168.1.1', 80);
sock.send(…);
sock.recv(…);
sock.close();

Alternatively, the module namespace can be imported using a wildcard import statement:

import * as socket from 'socket';

let sock = socket.create(socket.AF_INET, socket.SOCK_STREAM, 0);
sock.connect('192.168.1.1', 80);
sock.send(…);
sock.recv(…);
sock.close();

Additionally, the socket module namespace may also be imported by invoking the ucode interpreter with the -lsocket switch.

Source: lib/socket.c, line 17

Classes

socket.socket

Represents a socket handle.

Methods

addrinfo(hostname, serviceopt, hintsopt) → {AddressInfo[]}nullable

Resolves the given hostname and optional service name into a list of network addresses, according to the provided hints.

The addrinfo() function provides an API for performing DNS and service name resolution. It returns an array of objects, each representing a resolved address.

Returns an array of resolved addresses. Returns null if an error occurred during resolution.

Parameters:

Name Type Description

Name	Type	Description
`hostname`	string	The hostname to resolve.
`service`	string	(optional) Optional service name to resolve. If not provided, the service field of the resulting address information structures is left uninitialized.
`hints`	Object	(optional) Optional hints object that provides additional control over the resolution process. It can contain the following properties: `family`: The preferred address family (`AF_INET` or `AF_INET6`). `socktype`: The socket type (`SOCK_STREAM`, `SOCK_DGRAM`, etc.). `protocol`: The protocol of returned addresses. `flags`: Bitwise OR-ed `AI_*` flags to control the resolution behavior.

hostname

string

The hostname to resolve.

service

string

(optional)

Optional service name to resolve. If not provided, the service field of the resulting address information structures is left uninitialized.

hints

Object

(optional)

Optional hints object that provides additional control over the resolution process. It can contain the following properties:

family: The preferred address family (AF_INET or AF_INET6).
socktype: The socket type (SOCK_STREAM, SOCK_DGRAM, etc.).
protocol: The protocol of returned addresses.
flags: Bitwise OR-ed AI_* flags to control the resolution behavior.

Returns: AddressInfo[]

Example

// Resolve all addresses
const addresses = socket.addrinfo('example.org');

// Resolve IPv4 addresses for a given hostname and service
const ipv4addresses = socket.addrinfo('example.com', 'http', { family: socket.AF_INET });

// Resolve IPv6 addresses without specifying a service
const ipv6Addresses = socket.addrinfo('example.com', null, { family: socket.AF_INET6 });

Source: lib/socket.c, line 2395
See: Socket Types
Address Info Flags

connect(host, serviceopt, hintsopt, timeoutopt) → {socket}

Creates a network socket and connects it to the specified host and service.

This high level function combines the functionality of create(), addrinfo() and connect() to simplify connection establishment with the socket module.

Parameters:

Name	Type	Description
`host`	string \| number[] \| socket.SocketAddress	The host to connect to, can be an IP address, hostname, SocketAddress, or an array value returned by iptoarr().
`service`	string \| number	(optional) The service to connect to, can be a symbolic service name (such as "http") or a port number. Optional if host is specified as SocketAddress.
`hints`	Object	(optional) Optional preferences for the socket. It can contain the following properties: `family`: The preferred address family (`AF_INET` or `AF_INET6`). `socktype`: The socket type (`SOCK_STREAM`, `SOCK_DGRAM`, etc.). `protocol`: The protocol of the created socket. `flags`: Bitwise OR-ed `AI_*` flags to control the resolution behavior. If no hints are not provided, the default socket type preference is set to `SOCK_STREAM`.
`timeout`	number	(optional, default: `-1`) The timeout in milliseconds for socket connect operations. If set to a negative value, no specifc time limit is imposed and the function will block until either a connection was successfull or the underlying operating system timeout is reached.

Returns: socket

Example

// Resolve host, try to connect to both resulting IPv4 and IPv6 addresses
let conn = socket.connect("example.org", 80);

// Enforce usage of IPv6
let conn = socket.connect("example.com", 80, { family: socket.AF_INET6 });

// Connect a UDP socket
let conn = socket.connect("192.168.1.1", 53, { socktype: socket.SOCK_DGRAM });

// Bypass name resolution by specifying a SocketAddress structure
let conn = socket.connect({ address: "127.0.0.1", port: 9000 });

// Use SocketAddress structure to connect a UNIX domain socket
let conn = socket.connect({ path: "/var/run/daemon.sock" });

Source: lib/socket.c, line 2594

create(domainopt, typeopt, protocolopt) → {socket}nullable

Creates a network socket instance.

This function creates a new network socket with the specified domain and type, determined by one of the modules AF_* and SOCK_* constants respectively, and returns the resulting socket instance for use in subsequent socket operations.

The domain argument specifies the protocol family, such as AF_INET or AF_INET6, and defaults to AF_INET if not provided.

The type argument specifies the socket type, such as SOCK_STREAM or SOCK_DGRAM, and defaults to SOCK_STREAM if not provided. It may also be bitwise OR-ed with SOCK_NONBLOCK to enable non-blocking mode or SOCK_CLOEXEC to enable close-on-exec semantics.

The protocol argument may be used to indicate a particular protocol to be used with the socket, and it defaults to 0 (automatically determined protocol) if not provided.

Returns a socket descriptor representing the newly created socket.

Returns null if an error occurred during socket creation.

Parameters:

Name	Type	Description
`domain`	number	(optional, default: `AF_INET`) The communication domain for the socket, e.g., AF_INET or AF_INET6.
`type`	number	(optional, default: `SOCK_STREAM`) The socket type, e.g., SOCK_STREAM or SOCK_DGRAM. It may also be bitwise OR-ed with SOCK_NONBLOCK or SOCK_CLOEXEC.
`protocol`	number	(optional, default: `0`) The protocol to be used with the socket.

Returns: socket

A socket instance representing the newly created socket.

Example

// Create a TCP socket
const tcp_socket = create(AF_INET, SOCK_STREAM);

// Create a nonblocking IPv6 UDP socket
const udp_socket = create(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK);

Source: lib/socket.c, line 3027

error(numericopt) → {string|number}

Query error information.

Returns a string containing a description of the last occurred error when the numeric argument is absent or false.

Returns a positive (errno) or negative (EAI_* constant) error code number when the numeric argument is true.

Returns null if there is no error information.

Parameters:

Name	Type	Description
`numeric`	boolean	(optional) Whether to return a numeric error code (`true`) or a human readable error message (false).

Returns: string | number

Example

// Trigger socket error by attempting to bind IPv6 address with IPv4 socket
socket.create(socket.AF_INET, socket.SOCK_STREAM, 0).bind("::", 8080);

// Print error (should yield "Address family not supported by protocol")
print(socket.error(), "\n");

// Trigger resolve error
socket.addrinfo("doesnotexist.org");

// Query error code (should yield -2 for EAI_NONAME)
print(socket.error(true), "\n");  //

Source: lib/socket.c, line 2169

listen(host, serviceopt, hintsopt, backlogopt) → {socket}

Binds a listening network socket to the specified host and service.

This high-level function combines the functionality of create(), addrinfo(), bind(), and listen() to simplify setting up a listening socket with the socket module.

Parameters:

Name	Type	Description
`host`	string \| number[] \| socket.SocketAddress	The host to bind to, can be an IP address, hostname, SocketAddress, or an array value returned by iptoarr().
`service`	string \| number	(optional) The service to listen on, can be a symbolic service name (such as "http") or a port number. Optional if host is specified as SocketAddress.
`hints`	Object	(optional) Optional preferences for the socket. It can contain the following properties: `family`: The preferred address family (`AF_INET` or `AF_INET6`). `socktype`: The socket type (`SOCK_STREAM`, `SOCK_DGRAM`, etc.). `protocol`: The protocol of the created socket. `flags`: Bitwise OR-ed `AI_*` flags to control the resolution behavior. If no hints are provided, the default socket type preference is set to `SOCK_STREAM`.
`backlog`	number	(optional, default: `128`) The maximum length of the queue of pending connections.

Returns: socket

Example

// Listen for incoming TCP connections on port 80
let server = socket.listen("localhost", 80);

// Listen on IPv6 address only
let server = socket.listen("machine.local", 8080, { family: socket.AF_INET6 });

// Listen on a UNIX domain socket
let server = socket.listen({ path: "/var/run/server.sock" });

Source: lib/socket.c, line 2825

nameinfo(address, flagsopt) → {Object}nullable

Resolves the given network address into hostname and service name.

The nameinfo() function provides an API for reverse DNS lookup and service name resolution. It returns an object containing the following properties:

hostname: The resolved hostname.
service: The resolved service name.

Returns an object representing the resolved hostname and service name. Return null if an error occurred during resolution.

Parameters:

Name Type Description

Name	Type	Description
`address`	string \| socket.SocketAddress	The network address to resolve. It can be specified as: A string representing the IP address. An object representing the address with properties `address` and `port`.
`flags`	number	(optional) Optional flags that provide additional control over the resolution process, specified as bitwise OR-ed number of `NI_*` constants.

address

string | socket.SocketAddress

The network address to resolve. It can be specified as:

A string representing the IP address.
An object representing the address with properties address and port.

flags

number

(optional)

Optional flags that provide additional control over the resolution process, specified as bitwise OR-ed number of NI_* constants.

Returns: Object

Example

// Resolve a network address into hostname and service name
const result = network.getnameinfo('192.168.1.1:80');
print(result); // { "hostname": "example.com", "service": "http" }

Source: lib/socket.c, line 2332
See: Socket Types
AName Info Constants

poll(timeout, …sockets) → {PollSpec[]}

Polls a number of sockets for state changes.

Returns an array of [socket, flags] tuples for each socket with pending events. When a tuple is passed as socket argument, it is included as-is into the result tuple array, with the flags entry changed to a bitwise OR-ed value describing the pending events for this socket. When a plain socket instance (or another kind of handle) is passed, a new tuple array is created for this socket within the result tuple array, containing this socket as first and the bitwise OR-ed pending events as second element.

Returns null if an error occurred.

Parameters:

Name	Type	Description
`timeout`	number	Amount of milliseconds to wait for socket activity before aborting the poll call. If set to `0`, the poll call will return immediately if none of the provided sockets has pending events, if set to a negative value, the poll call will wait indefinitely, in all other cases the poll call will wait at most for the given amount of milliseconds before returning.
`sockets`	socket \| PollSpec	(repeatable) An arbitrary amount of socket arguments. Each argument may be either a plain socket instance (or any other kind of handle implementing a `fileno()` method) or a `[socket, flags]` tuple specifying the socket and requested poll flags. If a plain socket (or other kind of handle) instead of a tuple is provided, the requested poll flags default to `POLLIN\|POLLERR\|POLLHUP` for this socket.

Returns: PollSpec[]

Example

let x = socket.connect("example.org", 80);
let y = socket.connect("example.com", 80);

// Pass plain socket arguments
let events = socket.poll(10, x, y);
print(events); // [ [ "<socket 0x7>", 0 ], [ "<socket 0x8>", 0 ] ]

// Passing tuples allows attaching state information and requesting
// different I/O events
let events = socket.poll(10,
	[ x, socket.POLLOUT | socket.POLLHUP, "This is example.org" ],
	[ y, socket.POLLOUT | socket.POLLHUP, "This is example.com" ]
);
print(events); // [ [ "<socket 0x7>", 4, "This is example.org" ],
               //   [ "<socket 0x8>", 4, "This is example.com" ] ]

Source: lib/socket.c, line 2496

sockaddr(address) → {socket.SocketAddress}nullable

Parses the provided address value into a socket address representation.

This function parses the given address value into a socket address representation required for a number of socket operations. The address value can be provided in various formats:

For IPv4 addresses, it can be a string representing the IP address, optionally followed by a port number separated by colon, e.g. 192.168.0.1:8080.
For IPv6 addresses, it must be an address string enclosed in square brackets if a port number is specified, otherwise the brackets are optional. The address string may also include a scope ID in the form %ifname or %number, e.g. [fe80::1%eth0]:8080 or fe80::1%15.
Any string value containing a slash is treated as UNIX domain socket path.
Alternatively, it can be provided as an array returned by iptoarr(), representing the address octets.
It can also be an object representing a network address, with properties for address (the IP address) and port or a single property path to denote a UNIX domain socket address.

Parameters:

Name	Type	Description
`address`	string \| number[] \| socket.SocketAddress	The address value to parse.

Returns: socket.SocketAddress

A socket address representation of the provided address value, or null if the address could not be parsed.

Example

// Parse an IP address string with port
const address1 = sockaddr('192.168.0.1:8080');

// Parse an IPv6 address string with port and scope identifier
const address2 = sockaddr('[fe80::1%eth0]:8080');

// Parse an array representing an IP address
const address3 = sockaddr([192, 168, 0, 1]);

// Parse a network address object
const address4 = sockaddr({ address: '192.168.0.1', port: 8080 });

// Convert a path value to a UNIX domain socket address
const address5 = sockaddr('/var/run/daemon.sock');

Source: lib/socket.c, line 2264

Type Definitions

AddressInfo: Object

Represents a network address information object returned by addrinfo().

Properties

Name	Type	Attributes	Default	Description
`addr`	socket.SocketAddress			A socket address structure.
`canonname`	string	optional	null	(optional, default: `null`) The canonical hostname associated with the address.
`family`	number			The address family (e.g., `2` for `AF_INET`, `10` for `AF_INET6`).
`flags`	number			Additional flags indicating properties of the address.
`protocol`	number			The protocol number.
`socktype`	number			The socket type (e.g., `1` for `SOCK_STREAM`, `2` for `SOCK_DGRAM`).

Source: lib/socket.c, line 1272

PollSpec: Array

Represents a poll state serving as input parameter and return value type for poll().

Properties

Name	Type	Description
`0`	socket	The polled socket instance.
`1`	number	Requested or returned status flags of the polled socket instance.

Source: lib/socket.c, line 2484

Address Families

Constants representing address families and socket domains.

Properties

Name	Type	Description
`AF_UNSPEC`	number	Unspecified address family.
`AF_UNIX`	number	UNIX domain sockets.
`AF_INET`	number	IPv4 Internet protocols.
`AF_INET6`	number	IPv6 Internet protocols.
`AF_PACKET`	number	Low-level packet interface.

Source: lib/socket.c, line 4634

Address Info Flags

The AI_* flags may be passed as bitwise OR-ed number in the flags property of the hints dictionary argument of addrinfo().

Properties

Name	Type	Description
`AI_ADDRCONFIG`	number	Address configuration flag.
`AI_ALL`	number	Return IPv4 and IPv6 socket addresses.
`AI_CANONIDN`	number	Canonicalize using the IDNA standard.
`AI_CANONNAME`	number	Fill in the canonical name field.
`AI_IDN`	number	Enable IDN encoding.
`AI_NUMERICHOST`	number	Prevent hostname resolution.
`AI_NUMERICSERV`	number	Prevent service name resolution.
`AI_PASSIVE`	number	Use passive socket.
`AI_V4MAPPED`	number	Map IPv6 addresses to IPv4-mapped format.

Source: lib/socket.c, line 5162

IP Protocol Constants

The IPPROTO_IP constant specifies the IP protocol number and may be passed as third argument to create() as well as level argument value to getopt() and setopt().

The IP_* constants are option names recognized by getopt() and setopt(), in conjunction with the IPPROTO_IP socket level.

Properties

Name	Type	Description
`IPPROTO_IP`	number	Dummy protocol for IP.
`IP_ADD_MEMBERSHIP`	number	Add an IP group membership.
`IP_ADD_SOURCE_MEMBERSHIP`	number	Add an IP group/source membership.
`IP_BIND_ADDRESS_NO_PORT`	number	Bind to the device only.
`IP_BLOCK_SOURCE`	number	Block IP group/source.
`IP_DROP_MEMBERSHIP`	number	Drop an IP group membership.
`IP_DROP_SOURCE_MEMBERSHIP`	number	Drop an IP group/source membership.
`IP_FREEBIND`	number	Allow binding to an IP address not assigned to a network interface.
`IP_HDRINCL`	number	Header is included with data.
`IP_MSFILTER`	number	Filter IP multicast source memberships.
`IP_MTU`	number	Path MTU discovery.
`IP_MTU_DISCOVER`	number	Control Path MTU discovery.
`IP_MULTICAST_ALL`	number	Receive all multicast packets.
`IP_MULTICAST_IF`	number	Set outgoing interface for multicast packets.
`IP_MULTICAST_LOOP`	number	Control multicast packet looping.
`IP_MULTICAST_TTL`	number	Set time-to-live for outgoing multicast packets.
`IP_NODEFRAG`	number	Don't fragment IP packets.
`IP_OPTIONS`	number	Set/get IP options.
`IP_PASSSEC`	number	Pass security information.
`IP_PKTINFO`	number	Receive packet information.
`IP_RECVERR`	number	Receive all ICMP errors.
`IP_RECVOPTS`	number	Receive all IP options.
`IP_RECVORIGDSTADDR`	number	Receive original destination address of the socket.
`IP_RECVTOS`	number	Receive IP TOS.
`IP_RECVTTL`	number	Receive IP TTL.
`IP_RETOPTS`	number	Set/get IP options.
`IP_ROUTER_ALERT`	number	Receive ICMP msgs generated by router.
`IP_TOS`	number	IP type of service and precedence.
`IP_TRANSPARENT`	number	Transparent proxy support.
`IP_TTL`	number	IP time-to-live.
`IP_UNBLOCK_SOURCE`	number	Unblock IP group/source.

Source: lib/socket.c, line 4714

IPv6: Object

The IPPROTO_IPV6 constant specifies the IPv6 protocol number and may be passed as third argument to create() as well as level argument value to getopt() and setopt().

The IPV6_* constants are option names recognized by getopt() and setopt(), in conjunction with the IPPROTO_IPV6 socket level.

Properties

Name	Type	Description
`IPPROTO_IPV6`	number	The IPv6 protocol.
`IPV6_ADDRFORM`	number	Turn an AF_INET6 socket into a socket of a different address family. Only AF_INET is supported.
`IPV6_ADDR_PREFERENCES`	number	Specify preferences for address selection.
`IPV6_ADD_MEMBERSHIP`	number	Add an IPv6 group membership.
`IPV6_AUTHHDR`	number	Set delivery of the authentication header control message for incoming datagrams.
`IPV6_AUTOFLOWLABEL`	number	Enable or disable automatic flow labels.
`IPV6_DONTFRAG`	number	Control whether the socket allows IPv6 fragmentation.
`IPV6_DROP_MEMBERSHIP`	number	Drop an IPv6 group membership.
`IPV6_DSTOPTS`	number	Set delivery of the destination options control message for incoming datagrams.
`IPV6_FLOWINFO_SEND`	number	Control whether flow information is sent.
`IPV6_FLOWINFO`	number	Set delivery of the flow ID control message for incoming datagrams.
`IPV6_FLOWLABEL_MGR`	number	Manage flow labels.
`IPV6_FREEBIND`	number	Allow binding to an IP address not assigned to a network interface.
`IPV6_HOPLIMIT`	number	Set delivery of the hop limit control message for incoming datagrams.
`IPV6_HOPOPTS`	number	Set delivery of the hop options control message for incoming datagrams.
`IPV6_JOIN_ANYCAST`	number	Join an anycast group.
`IPV6_LEAVE_ANYCAST`	number	Leave an anycast group.
`IPV6_MINHOPCOUNT`	number	Set the minimum hop count.
`IPV6_MTU`	number	Retrieve or set the MTU to be used for the socket.
`IPV6_MTU_DISCOVER`	number	Control path-MTU discovery on the socket.
`IPV6_MULTICAST_ALL`	number	Control whether the socket receives all multicast packets.
`IPV6_MULTICAST_HOPS`	number	Set the multicast hop limit for the socket.
`IPV6_MULTICAST_IF`	number	Set the device for outgoing multicast packets on the socket.
`IPV6_MULTICAST_LOOP`	number	Control whether the socket sees multicast packets that it has sent itself.
`IPV6_PKTINFO`	number	Set delivery of the IPV6_PKTINFO control message on incoming datagrams.
`IPV6_RECVDSTOPTS`	number	Control receiving of the destination options control message.
`IPV6_RECVERR`	number	Control receiving of asynchronous error options.
`IPV6_RECVFRAGSIZE`	number	Control receiving of fragment size.
`IPV6_RECVHOPLIMIT`	number	Control receiving of hop limit.
`IPV6_RECVHOPOPTS`	number	Control receiving of hop options.
`IPV6_RECVORIGDSTADDR`	number	Control receiving of the original destination address.
`IPV6_RECVPATHMTU`	number	Control receiving of path MTU.
`IPV6_RECVPKTINFO`	number	Control receiving of packet information.
`IPV6_RECVRTHDR`	number	Control receiving of routing header.
`IPV6_RECVTCLASS`	number	Control receiving of traffic class.
`IPV6_ROUTER_ALERT_ISOLATE`	number	Control isolation of router alert messages.
`IPV6_ROUTER_ALERT`	number	Pass forwarded packets containing a router alert hop-by-hop option to this socket.
`IPV6_RTHDR`	number	Set delivery of the routing header control message for incoming datagrams.
`IPV6_RTHDRDSTOPTS`	number	Set delivery of the routing header destination options control message.
`IPV6_TCLASS`	number	Set the traffic class.
`IPV6_TRANSPARENT`	number	Enable transparent proxy support.
`IPV6_UNICAST_HOPS`	number	Set the unicast hop limit for the socket.
`IPV6_UNICAST_IF`	number	Set the interface for outgoing unicast packets.
`IPV6_V6ONLY`	number	Restrict the socket to sending and receiving IPv6 packets only.

Source: lib/socket.c, line 4793

Message Flags

The MSG_* flag constants are commonly used in conjunction with the send() and recv() functions.

Properties

Name	Type	Description
`MSG_CONFIRM`	number	Confirm path validity.
`MSG_DONTROUTE`	number	Send without using routing tables.
`MSG_DONTWAIT`	number	Enables non-blocking operation.
`MSG_EOR`	number	End of record.
`MSG_MORE`	number	Sender will send more.
`MSG_NOSIGNAL`	number	Do not generate SIGPIPE.
`MSG_OOB`	number	Process out-of-band data.
`MSG_FASTOPEN`	number	Send data in TCP SYN.
`MSG_CMSG_CLOEXEC`	number	Sets the close-on-exec flag on the received file descriptor.
`MSG_ERRQUEUE`	number	Receive errors from ICMP.
`MSG_PEEK`	number	Peeks at incoming messages.
`MSG_TRUNC`	number	Report if datagram truncation occurred.
`MSG_WAITALL`	number	Wait for full message.

Source: lib/socket.c, line 4677

Name Info Constants

The NI_* flags may be passed as bitwise OR-ed number via the flags argument of nameinfo().

Properties

Name	Type	Description
`NI_DGRAM`	number	Datagram socket type.
`NI_IDN`	number	Enable IDN encoding.
`NI_NAMEREQD`	number	Hostname resolution required.
`NI_NOFQDN`	number	Do not force fully qualified domain name.
`NI_NUMERICHOST`	number	Return numeric form of the hostname.
`NI_NUMERICSERV`	number	Return numeric form of the service name.

Source: lib/socket.c, line 5189

Packet Socket Constants

The SOL_PACKET constant specifies the packet socket level and may be passed as level argument value to getopt() and setopt().

Most PACKET_* constants are option argument values recognized by getopt() and setopt(), in conjunction with the SOL_PACKET socket level.

The constants PACKET_MR_PROMISC, PACKET_MR_MULTICAST and PACKET_MR_ALLMULTI are used in conjunction with the PACKET_ADD_MEMBERSHIP and PACKET_DROP_MEMBERSHIP options to specify the packet socket receive mode.

The constants PACKET_HOST, PACKET_BROADCAST, PACKET_MULTICAST, PACKET_OTHERHOST and PACKET_OUTGOING may be used as packet_type value in socket address structures.

Properties

Name	Type	Description
`SOL_PACKET`	number	Socket options at the packet API level.
`PACKET_ADD_MEMBERSHIP`	number	Add a multicast group membership.
`PACKET_DROP_MEMBERSHIP`	number	Drop a multicast group membership.
`PACKET_AUXDATA`	number	Receive auxiliary data (packet info).
`PACKET_FANOUT`	number	Configure packet fanout.
`PACKET_LOSS`	number	Retrieve the current packet loss statistics.
`PACKET_RESERVE`	number	Reserve space for packet headers.
`PACKET_RX_RING`	number	Configure a receive ring buffer.
`PACKET_STATISTICS`	number	Retrieve packet statistics.
`PACKET_TIMESTAMP`	number	Retrieve packet timestamps.
`PACKET_TX_RING`	number	Configure a transmit ring buffer.
`PACKET_VERSION`	number	Set the packet protocol version.
`PACKET_QDISC_BYPASS`	number	Bypass queuing discipline for outgoing packets.
`PACKET_MR_PROMISC`	number	Enable promiscuous mode.
`PACKET_MR_MULTICAST`	number	Receive multicast packets.
`PACKET_MR_ALLMULTI`	number	Receive all multicast packets.
`PACKET_HOST`	number	Receive packets destined for this host.
`PACKET_BROADCAST`	number	Receive broadcast packets.
`PACKET_MULTICAST`	number	Receive multicast packets.
`PACKET_OTHERHOST`	number	Receive packets destined for other hosts.
`PACKET_OUTGOING`	number	Transmit packets.

Source: lib/socket.c, line 5053

Poll Event Constants

The following constants represent event types for polling operations and are set or returned as part of a PollSpec tuple by the poll() function. When passed via an argument PollSpec to poll(), they specify the I/O events to watch for on the corresponding handle. When appearing in a PollSpec returned by poll(), they specify the I/O events that occurred on a watched handle.

Properties

Name	Type	Description
`POLLIN`	number	Data available to read.
`POLLPRI`	number	Priority data available to read.
`POLLOUT`	number	Writable data available.
`POLLERR`	number	Error condition.
`POLLHUP`	number	Hang up.
`POLLNVAL`	number	Invalid request.
`POLLRDHUP`	number	Peer closed or shutdown writing.

Source: lib/socket.c, line 5211

Shutdown Constants

The SHUT_* constants are passed as argument to the shutdown() function to specify which direction of a full duplex connection to shut down.

Properties

Name	Type	Description
`SHUT_RD`	number	Disallow further receptions.
`SHUT_WR`	number	Disallow further transmissions.
`SHUT_RDWR`	number	Disallow further receptions and transmissions.

Source: lib/socket.c, line 5147

Socket Option Constants

The SOL_SOCKET constant is passed as level argument to the getopt() and setopt() functions in order to set or retrieve generic socket option values.

The SO_* constants are passed as option argument in conjunction with the SOL_SOCKET level to specify the specific option to get or set on the socket.

Properties

Name	Type	Description
`SOL_SOCKET`	number	Socket options at the socket API level.
`SO_ACCEPTCONN`	number	Reports whether socket listening is enabled.
`SO_ATTACH_BPF`	number	Attach BPF program to socket.
`SO_ATTACH_FILTER`	number	Attach a socket filter.
`SO_ATTACH_REUSEPORT_CBPF`	number	Attach BPF program for cgroup and skb program reuseport hook.
`SO_ATTACH_REUSEPORT_EBPF`	number	Attach eBPF program for cgroup and skb program reuseport hook.
`SO_BINDTODEVICE`	number	Bind socket to a specific interface.
`SO_BROADCAST`	number	Allow transmission of broadcast messages.
`SO_BUSY_POLL`	number	Enable busy polling.
`SO_DEBUG`	number	Enable socket debugging.
`SO_DETACH_BPF`	number	Detach BPF program from socket.
`SO_DETACH_FILTER`	number	Detach a socket filter.
`SO_DOMAIN`	number	Retrieves the domain of the socket.
`SO_DONTROUTE`	number	Send packets directly without routing.
`SO_ERROR`	number	Retrieves and clears the error status for the socket.
`SO_INCOMING_CPU`	number	Retrieves the CPU number on which the last packet was received.
`SO_INCOMING_NAPI_ID`	number	Retrieves the NAPI ID of the device.
`SO_KEEPALIVE`	number	Enable keep-alive packets.
`SO_LINGER`	number	Set linger on close.
`SO_LOCK_FILTER`	number	Set or get the socket filter lock state.
`SO_MARK`	number	Set the mark for packets sent through the socket.
`SO_OOBINLINE`	number	Enables out-of-band data to be received in the normal data stream.
`SO_PASSCRED`	number	Enable the receiving of SCM_CREDENTIALS control messages.
`SO_PASSSEC`	number	Enable the receiving of security context.
`SO_PEEK_OFF`	number	Returns the number of bytes in the receive buffer without removing them.
`SO_PEERCRED`	number	Retrieves the credentials of the foreign peer.
`SO_PEERSEC`	number	Retrieves the security context of the foreign peer.
`SO_PRIORITY`	number	Set the protocol-defined priority for all packets.
`SO_PROTOCOL`	number	Retrieves the protocol number.
`SO_RCVBUF`	number	Set the receive buffer size.
`SO_RCVBUFFORCE`	number	Set the receive buffer size forcefully.
`SO_RCVLOWAT`	number	Set the minimum number of bytes to process for input operations.
`SO_RCVTIMEO`	number	Set the timeout for receiving data.
`SO_REUSEADDR`	number	Allow the socket to be bound to an address that is already in use.
`SO_REUSEPORT`	number	Enable duplicate address and port bindings.
`SO_RXQ_OVFL`	number	Reports if the receive queue has overflown.
`SO_SNDBUF`	number	Set the send buffer size.
`SO_SNDBUFFORCE`	number	Set the send buffer size forcefully.
`SO_SNDLOWAT`	number	Set the minimum number of bytes to process for output operations.
`SO_SNDTIMEO`	number	Set the timeout for sending data.
`SO_TIMESTAMP`	number	Enable receiving of timestamps.
`SO_TIMESTAMPNS`	number	Enable receiving of nanosecond timestamps.
`SO_TYPE`	number	Retrieves the type of the socket (e.g., SOCK_STREAM).

Source: lib/socket.c, line 4897

Socket Types

The SOCK_* type and flag constants are used by create() to specify the type of socket to open. The accept() function recognizes the SOCK_NONBLOCK and SOCK_CLOEXEC flags and applies them to accepted peer sockets.

Properties

Name	Type	Description
`SOCK_STREAM`	number	Provides sequenced, reliable, two-way, connection-based byte streams.
`SOCK_DGRAM`	number	Supports datagrams (connectionless, unreliable messages of a fixed maximum length).
`SOCK_RAW`	number	Provides raw network protocol access.
`SOCK_PACKET`	number	Obsolete and should not be used.
`SOCK_NONBLOCK`	number	Enables non-blocking operation.
`SOCK_CLOEXEC`	number	Sets the close-on-exec flag on the new file descriptor.

Source: lib/socket.c, line 4652

TCP Protocol Constants

The IPPROTO_TCP constant specifies the TCP protocol number and may be passed as third argument to create() as well as level argument value to getopt() and setopt().

The TCP_* constants are option argument values recognized by getopt() and setopt(), in conjunction with the IPPROTO_TCP socket level.

Properties

Name	Type	Description
`IPPROTO_TCP`	number	TCP protocol.
`TCP_CONGESTION`	number	Set the congestion control algorithm.
`TCP_CORK`	number	Delay packet transmission until full-sized packets are available.
`TCP_DEFER_ACCEPT`	number	Delay accepting incoming connections until data arrives.
`TCP_FASTOPEN`	number	Enable TCP Fast Open.
`TCP_FASTOPEN_CONNECT`	number	Perform TFO connect.
`TCP_INFO`	number	Retrieve TCP statistics.
`TCP_KEEPCNT`	number	Number of keepalive probes.
`TCP_KEEPIDLE`	number	Time before keepalive probes begin.
`TCP_KEEPINTVL`	number	Interval between keepalive probes.
`TCP_LINGER2`	number	Lifetime of orphaned FIN_WAIT2 state sockets.
`TCP_MAXSEG`	number	Maximum segment size.
`TCP_NODELAY`	number	Disable Nagle's algorithm.
`TCP_QUICKACK`	number	Enable quick ACKs.
`TCP_SYNCNT`	number	Number of SYN retransmits.
`TCP_USER_TIMEOUT`	number	Set the user timeout.
`TCP_WINDOW_CLAMP`	number	Set the maximum window.

Source: lib/socket.c, line 5002

UDP Protocol Constants

The IPPROTO_UDP constant specifies the UDP protocol number and may be passed as third argument to create() as well as level argument value to getopt() and setopt().

The UDP_* constants are option argument values recognized by getopt() and setopt(), in conjunction with the IPPROTO_UDP socket level.

Properties

Name	Type	Description
`IPPROTO_UDP`	number	UDP protocol.
`UDP_CORK`	number	Cork data until flush.

Source: lib/socket.c, line 5126