Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

AF_UNIX (int)

Socket address family of filesystem pathnames in the Unix Domain.

AF_INET (int)

Socket address family of IPv4 in the Internet Domain.

AF_INET6 (int)

Socket address family of IPv6 in the Internet Domain. Only available if compiled with IPv6 support.

AF_DIVERT (int)

Socket address family for the FreeBSD divert(4) interface, used to receive packets diverted by the firewall. Available as of PHP 8.3.0 (FreeBSD only).

AF_PACKET (int)

Socket address family for low-level packet sockets, used to send and receive raw packets at the device-driver (OSI layer 2) level. Available as of PHP 8.5.0 (Linux only).

SOCK_STREAM (int)

SOCK_DGRAM (int)

SOCK_RAW (int)

SOCK_SEQPACKET (int)

SOCK_RDM (int)

SOCK_CONN_DGRAM (int)

Set the socket to a connection-oriented datagram. Available as of PHP 8.4.0. (NetBSD only)

SOCK_DCCP (int)

Set the socket to a datagram congestion control protocol. Available as of PHP 8.4.0. (NetBSD only)

SOCK_NONBLOCK (int)

Set the non-blocking socket status flag. Available as of PHP 8.4.0.

SOCK_CLOEXEC (int)

Set the close-on-exec socket status flag. Available as of PHP 8.4.0.

MSG_OOB (int)

MSG_WAITALL (int)

MSG_PEEK (int)

MSG_DONTROUTE (int)

MSG_EOR (int)

Not available on Windows platforms.

MSG_EOF (int)

Not available on Windows platforms.

MSG_ZEROCOPY (int)

Available as of PHP 8.2.0

SO_DEBUG (int)

SO_REUSEADDR (int)

SO_REUSEPORT (int)

This constant is only available on platforms that support the SO_REUSEPORT socket option: this includes Linux, macOS and *BSD, but does not include Windows.

SO_KEEPALIVE (int)

SO_DONTROUTE (int)

SO_LINGER (int)

SO_BROADCAST (int)

SO_OOBINLINE (int)

SO_SNDBUF (int)

SO_RCVBUF (int)

SO_SNDLOWAT (int)

SO_RCVLOWAT (int)

SO_SNDTIMEO (int)

SO_RCVTIMEO (int)

SO_TYPE (int)

SO_ERROR (int)

SO_ZEROCOPY (int)

Available as of PHP 8.2.0

TCP_NODELAY (int)

Used to disable Nagle TCP algorithm.

TCP_KEEPCNT (int)

Available as of PHP 8.2.0

TCP_KEEPIDLE (int)

Available as of PHP 8.2.0

TCP_KEEPINTVL (int)

Available as of PHP 8.2.0

TCP_KEEPALIVE (int)

Available as of PHP 8.2.0

TCP_NOTSENT_LOWAT (int)

Available as of PHP 8.2.0

SO_MARK (int)

Available as of PHP 8.1.0

SO_USER_COOKIE (int)

Available as of PHP 8.1.0

SO_RTABLE (int)

Available as of PHP 8.2.0

SO_ACCEPTFILTER (int)

Available as of PHP 8.1.0

SO_DONTTRUNC (int)

Available as of PHP 8.1.0

SO_WANTMORE (int)

Available as of PHP 8.1.0

SO_INCOMING_CPU (int)

Available as of PHP 8.2.0

SO_MEMINFO (int)

Available as of PHP 8.2.0

SO_BPF_EXTENSIONS (int)

Available as of PHP 8.2.0

SO_SETFIB (int)

Available as of PHP 8.2.0

SO_ATTACH_REUSEPORT_CBPF (int)

Available as of PHP 8.3.0 (Linux only)

SO_DETACH_BPF (int)

Available as of PHP 8.3.0 (Linux only)

SO_DETACH_FILTER (int)

Available as of PHP 8.3.0 (Linux only)

SO_RERROR (int)

Available as of PHP 8.3.0 (NetBSD only)

SO_ZEROIZE (int)

Available as of PHP 8.3.0 (OpenBSD only)

SO_SPLICE (int)

Available as of PHP 8.3.0 (OpenBSD only)

SO_REUSEPORT_LB (int)

Available as of PHP 8.3.0 (FreeBSD only)

SOL_FILTER (int)

Available as of PHP 8.2.0

SOL_UDPLITE (int)

Available as of PHP 8.3.0

UDPLITE_RECV_CSCOV (int)

Available as of PHP 8.3.0

UDPLITE_SEND_CSCOV (int)

Available as of PHP 8.3.0

TCP_DEFER_ACCEPT (int)

Available as of PHP 8.1.0

TCP_CONGESTION (int)

Available as of PHP 8.2.0

TCP_QUICKACK (int)

Available as of PHP 8.3.0 (Linux only)

TCP_REPAIR (int)

Available as of PHP 8.3.0 (Linux only)

TCP_SYNCNT (int)

Set the number of SYN retransmits that TCP should send before aborting the attempt to connect. Available as of PHP 8.4.0 (Linux only)

IP_DONTFRAG (int)

Available as of PHP 8.3.0 (FreeBSD only)

IP_MTU_DISCOVER (int)

Available as of PHP 8.3.0 (Linux only)

IP_PMTUDISC_DO (int)

Available as of PHP 8.3.0 (Linux only)

IP_PMTUDISC_DONT (int)

Available as of PHP 8.3.0 (Linux only)

IP_PMTUDISC_WANT (int)

Available as of PHP 8.3.0 (Linux only)

IP_PMTUDISC_PROBE (int)

Available as of PHP 8.3.0 (Linux only)

IP_PMTUDISC_INTERFACE (int)

Available as of PHP 8.3.0 (Linux only)

IP_PMTUDISC_OMIT (int)

Available as of PHP 8.3.0 (Linux only)

IP_BIND_ADDRESS_NO_PORT (int)

Available as of PHP 8.3.0 (Linux only)

SOL_SOCKET (int)

PHP_NORMAL_READ (int)

PHP_BINARY_READ (int)

SOL_TCP (int)

SOL_UDP (int)

The following constants are defined under Windows and UNIX-like platforms. Each constant is only defined if their equal is available on the platform.

SOCKET_EINTR (int)

Interrupted system call.

SOCKET_EBADF (int)

Bad file descriptor number.

SOCKET_EACCES (int)

Permission denied.

SOCKET_EFAULT (int)

Bad address.

SOCKET_EINVAL (int)

Invalid argument.

SOCKET_EMFILE (int)

Too many open files.

SOCKET_ENAMETOOLONG (int)

File name too long.

SOCKET_ENOTEMPTY (int)

Directory not empty.

SOCKET_ELOOP (int)

Too many symbolic links encountered.

SOCKET_EWOULDBLOCK (int)

Operation would block.

SOCKET_EREMOTE (int)

Object is remote.

SOCKET_EUSERS (int)

Too many users.

SOCKET_ENOTSOCK (int)

Socket operation on non-socket.

SOCKET_EDESTADDRREQ (int)

Destination address required.

SOCKET_EMSGSIZE (int)

Message too long.

SOCKET_EPROTOTYPE (int)

Protocol wrong type for socket.

SOCKET_EPROTONOSUPPORT (int)

Protocol not supported.

SOCKET_ESOCKTNOSUPPORT (int)

Socket type not supported.

SOCKET_EOPNOTSUPP (int)

Operation not supported on transport endpoint.

SOCKET_EPFNOSUPPORT (int)

Protocol family not supported.

SOCKET_EAFNOSUPPORT (int)

Address family not supported by protocol.

SOCKET_EADDRNOTAVAIL (int)

Cannot assign requested address.

SOCKET_ENETDOWN (int)

Network is down.

SOCKET_ENETUNREACH (int)

Network is unreachable.

SOCKET_ENETRESET (int)

Network dropped connection because of reset.

SOCKET_ECONNABORTED (int)

Software caused connection abort.

SOCKET_ECONNRESET (int)

Connection reset by peer.

SOCKET_ENOBUFS (int)

No buffer space available.

SOCKET_EISCONN (int)

Transport endpoint is already connected.

SOCKET_ENOTCONN (int)

Transport endpoint is not connected.

SOCKET_ESHUTDOWN (int)

Cannot send after transport endpoint shutdown.

SOCKET_ETIMEDOUT (int)

Connection timed out.

SOCKET_ECONNREFUSED (int)

Connection refused.

SOCKET_EHOSTDOWN (int)

Host is down.

SOCKET_EHOSTUNREACH (int)

No route to host.

SOCKET_EALREADY (int)

Operation already in progress.

SOCKET_EINPROGRESS (int)

Operation now in progress.

The following constants are only defined under Windows.

SOCKET_ENOPROTOOPT (int)

SOCKET_EADDRINUSE (int)

SOCKET_ETOOMYREFS (int)

SOCKET_EPROCLIM (int)

SOCKET_EDUOT (int)

SOCKET_ESTALE (int)

SOCKET_EDISCON (int)

SOCKET_SYSNOTREADY (int)

SOCKET_VERNOTSUPPORTED (int)

SOCKET_NOTINITIALISED (int)

SOCKET_HOST_NOT_FOUND (int)

SOCKET_TRY_AGAIN (int)

SOCKET_NO_RECOVERY (int)

SOCKET_NO_DATA (int)

SOCKET_NO_ADDRESS (int)

The following constants are only available on UNIX-like platforms. Each constant is only defined if their equal is available on the platform.

SOCKET_EPERM (int)

Operation not permitted.

SOCKET_ENOENT (int)

No such file or directory.

SOCKET_EIO (int)

I/O error.

SOCKET_ENXIO (int)

No such device or address.

SOCKET_E2BIG (int)

Arg list too long.

SOCKET_EAGAIN (int)

Try again.

SOCKET_ENOMEM (int)

Out of memory.

SOCKET_ENOTBLK (int)

Block device required.

SOCKET_EBUSY (int)

Device or resource busy.

SOCKET_EEXIST (int)

File exists.

SOCKET_EXDEV (int)

Cross-device link.

SOCKET_ENODEV (int)

No such device.

SOCKET_ENOTDIR (int)

Not a directory.

SOCKET_EISDIR (int)

Is a directory.

SOCKET_ENFILE (int)

File table overflow.

SOCKET_ENOTTY (int)

Not a typewriter.

SOCKET_ENOSPC (int)

No space left on device.

SOCKET_ESPIPE (int)

Illegal seek.

SOCKET_EROFS (int)

Read-only file system.

SOCKET_EMLINK (int)

Too many links.

SOCKET_EPIPE (int)

Broken pipe.

SOCKET_ENOLCK (int)

No record locks available.

SOCKET_ENOSYS (int)

Function not implemented.

SOCKET_ENOMSG (int)

No message of desired type.

SOCKET_EIDRM (int)

Identifier removed.

SOCKET_ECHRNG (int)

Channel number out of range.

SOCKET_EL2NSYNC (int)

Level 2 not synchronized.

SOCKET_EL3HLT (int)

Level 3 halted.

SOCKET_EL3RST (int)

Level 3 reset.

SOCKET_ELNRNG (int)

Link number out of range.

SOCKET_EUNATCH (int)

Protocol driver not attached.

SOCKET_ENOCSI (int)

No CSI structure available.

SOCKET_EL2HLT (int)

Level 2 halted.

SOCKET_EBADE (int)

Invalid exchange.

SOCKET_EBADR (int)

Invalid request descriptor.

SOCKET_EXFULL (int)

Exchange full.

SOCKET_ENOANO (int)

No anode.

SOCKET_EBADRQC (int)

Invalid request code.

SOCKET_EBADSLT (int)

Invalid slot.

SOCKET_ENOSTR (int)

Device not a stream.

SOCKET_ENODATA (int)

No data available.

SOCKET_ETIME (int)

Timer expired.

SOCKET_ENOSR (int)

Out of streams resources.

SOCKET_ENONET (int)

Machine is not on the network.

SOCKET_ENOLINK (int)

Link has been severed.

SOCKET_EADV (int)

Advertise error.

SOCKET_ESRMNT (int)

Srmount error.

SOCKET_ECOMM (int)

Communication error on send.

SOCKET_EPROTO (int)

Protocol error.

SOCKET_EMULTIHOP (int)

Multihop attempted.

SOCKET_EBADMSG (int)

Not a data message.

SOCKET_ENOTUNIQ (int)

Name not unique on network.

SOCKET_EBADFD (int)

File descriptor in bad state.

SOCKET_EREMCHG (int)

Remote address changed.

SOCKET_ERESTART (int)

Interrupted system call should be restarted.

SOCKET_ESTRPIPE (int)

Streams pipe error.

SOCKET_EPROTOOPT (int)

Protocol not available.

SOCKET_ADDRINUSE (int)

Address already in use.

SOCKET_ETOOMANYREFS (int)

Too many references: cannot splice.

SOCKET_EISNAM (int)

Is a named type file.

SOCKET_EREMOTEIO (int)

Remote I/O error.

SOCKET_EDQUOT (int)

Quota exceeded.

SOCKET_ENOMEDIUM (int)

No medium found.

SOCKET_EMEDIUMTYPE (int)

Wrong medium type.

SCM_RIGHTS (int)

Send or receive a set of open file descriptors from another process.

SCM_CREDENTIALS (int)

SCM_CREDS (int)

Available as of PHP 8.2.0

SCM_CREDS2 (int)

Available as of PHP 8.2.0

LOCAL_CREDS (int)

Available as of PHP 8.2.0

LOCAL_CREDS_PERSISTENT (int)

Available as of PHP 8.2.0

SKF_AD_OFF (int)

Available as of PHP 8.2.0

SKF_AD_PROTOCOL (int)

Available as of PHP 8.2.0

SKF_AD_PKTTYPE (int)

Available as of PHP 8.2.0

SKF_AD_IFINDEX (int)

Available as of PHP 8.2.0

SKF_AD_NLATTR (int)

Available as of PHP 8.2.0

SKF_AD_NLATTR_NEST (int)

Available as of PHP 8.2.0

SKF_AD_MARK (int)

Available as of PHP 8.2.0

SKF_AD_QUEUE (int)

Available as of PHP 8.2.0

SKF_AD_HATYPE (int)

Available as of PHP 8.2.0

SKF_AD_RXHASH (int)

Available as of PHP 8.2.0

SKF_AD_CPU (int)

Available as of PHP 8.2.0

SKF_AD_ALU_XOR_X (int)

Available as of PHP 8.2.0

SKF_AD_VLAN_TAG (int)

Available as of PHP 8.2.0

SKF_AD_VLAN_TAG_PRESENT (int)

Available as of PHP 8.2.0

SKF_AD_PAY_OFFSET (int)

Available as of PHP 8.2.0

SKF_AD_RANDOM (int)

Available as of PHP 8.2.0

SKF_AD_VLAN_TPID (int)

Available as of PHP 8.2.0

SKF_AD_MAX (int)

Available as of PHP 8.2.0

AI_ADDRCONFIG (int)

AI_ALL (int)

AI_CANONIDN (int)

AI_CANONNAME (int)

AI_IDN (int)

AI_NUMERICHOST (int)

AI_NUMERICSERV (int)

AI_PASSIVE (int)

AI_V4MAPPED (int)

FIL_ATTACH (int)

FIL_DETACH (int)

IPPROTO_IP (int)

IPPROTO_IPV6 (int)

IPV6_HOPLIMIT (int)

IPV6_MULTICAST_HOPS (int)

IPV6_MULTICAST_IF (int)

IPV6_MULTICAST_LOOP (int)

IPV6_PKTINFO (int)

IPV6_RECVHOPLIMIT (int)

IPV6_RECVPKTINFO (int)

IPV6_RECVTCLASS (int)

IPV6_TCLASS (int)

IPV6_UNICAST_HOPS (int)

IPV6_V6ONLY (int)

IP_MULTICAST_IF (int)

IP_MULTICAST_LOOP (int)

IP_MULTICAST_TTL (int)

IP_PORTRANGE (int)

Set the port range used for selecting a local port number. Available as of PHP 8.4.0. (FreeBSD/NetBSD/OpenBSD only)

IP_PORTRANGE_DEFAULT (int)

Use the default range of port values. Available as of PHP 8.4.0. (FreeBSD/NetBSD/OpenBSD only)

IP_PORTRANGE_HIGH (int)

Use a high range of port values. Available as of PHP 8.4.0. (FreeBSD/NetBSD/OpenBSD only)

IP_PORTRANGE_LOW (int)

Use a low range of port values. Available as of PHP 8.4.0. (FreeBSD/NetBSD/OpenBSD only)

MCAST_BLOCK_SOURCE (int)

MCAST_JOIN_GROUP (int)

MCAST_JOIN_SOURCE_GROUP (int)

MCAST_LEAVE_GROUP (int)

MCAST_LEAVE_SOURCE_GROUP (int)

MCAST_UNBLOCK_SOURCE (int)

MSG_CMSG_CLOEXEC (int)

MSG_CONFIRM (int)

MSG_CTRUNC (int)

MSG_DONTWAIT (int)

MSG_ERRQUEUE (int)

MSG_MORE (int)

MSG_NOSIGNAL (int)

MSG_TRUNC (int)

MSG_WAITFORONE (int)

SOL_LOCAL (int)

SOMAXCONN (int)

SO_BINDTODEVICE (int)

SO_FAMILY (int)

SO_LABEL (int)

SO_LISTENQLEN (int)

SO_LISTENQLIMIT (int)

SO_PASSCRED (int)

SO_PEERLABEL (int)

SO_EXCLUSIVEADDRUSE (int)

Prevents other sockets from being forcibly bound to the same address and port. Available as of PHP 8.4.0. (Windows only)

SO_EXCLBIND (int)

Enable/disable exclusive binding of the socket. Available as of PHP 8.4.0. (Solaris only)

SO_NOSIGPIPE (int)

Controls generation of SIGPIPE for the socket. Available as of PHP 8.4.0. (macOs and FreeBSD only)

SO_LINGER_SEC (int)

Similar to SO_LINGER but lingering is in seconds as opposed to time clicks on macOs. Available as of PHP 8.4.0. (macOs only)

SO_BINDTOIFINDEX (int)

Bind a socket to a specific network interface by its index. Available as of PHP 8.4.0.

SHUT_RD (int)

Disables further receive operations on the socket. Used with socket_shutdown(). Available as of PHP 8.5.0.

SHUT_WR (int)

Disables further send operations on the socket. Used with socket_shutdown(). Available as of PHP 8.5.0.

SHUT_RDWR (int)

Disables further send and receive operations on the socket. Used with socket_shutdown(). Available as of PHP 8.5.0.

UDP_SEGMENT (int)

Sets the maximum size of UDP Generic Segmentation Offload (GSO) segments, allowing multiple datagrams to be sent in a single system call. Available on Linux only. Available as of PHP 8.5.0.

SO_BUSY_POLL (int)

Sets the approximate time in microseconds to busy poll on a blocking receive when there is no data. This reduces latency at the cost of CPU. Available on Linux only. Available as of PHP 8.5.0.

IP_BINDANY (int)

Allows binding a socket to any address, even if it is not local. Available on FreeBSD, NetBSD, and OpenBSD only. Available as of PHP 8.5.0.

TCP_FUNCTION_BLK (int)

Selects the TCP stack (function block) used by the socket. With socket_set_option() the value is the name of the stack as a string; socket_get_option() returns an array with the function_set_name and pcbcnt keys. Available on FreeBSD only. Available as of PHP 8.5.0.

TCP_FUNCTION_ALIAS (int)

Retrieves the alias of the TCP stack used by the socket, as an array with the function_set_name and pcbcnt keys. Available on FreeBSD only. Available as of PHP 8.5.0.

TCP_REUSPORT_LB_NUMA (int)

Controls NUMA domain affinity for load-balanced port reuse. Available on FreeBSD only. Available as of PHP 8.5.0.

TCP_REUSPORT_LB_NUMA_NODOM (int)

Constant value for TCP_REUSPORT_LB_NUMA indicating no NUMA domain affinity. Available on FreeBSD only. Available as of PHP 8.5.0.

TCP_REUSPORT_LB_NUMA_CURDOM (int)

Constant value for TCP_REUSPORT_LB_NUMA indicating affinity for the current NUMA domain. Available on FreeBSD only. Available as of PHP 8.5.0.

TCP_BBR_ALGORITHM (int)

Socket option related to the BBR (Bottleneck Bandwidth and Round-trip propagation time) congestion control algorithm. Available on FreeBSD only. Available as of PHP 8.5.0.

IPPROTO_ICMP (int)

Internet Control Message Protocol (ICMP) protocol number, used when creating raw sockets. Available as of PHP 8.5.0.

IPPROTO_ICMPV6 (int)

Internet Control Message Protocol version 6 (ICMPv6) protocol number, used when creating raw IPv6 sockets. Available as of PHP 8.5.0.