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): Available as of PHP 8.3.0 (FreeBSD 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.