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 
    (integer)
   AF_INET 
    (integer)
   AF_INET6 
    (integer)
   SOCK_STREAM 
    (integer)
   SOCK_DGRAM 
    (integer)
   SOCK_RAW 
    (integer)
   SOCK_SEQPACKET 
    (integer)
   SOCK_RDM 
    (integer)
   MSG_OOB 
    (integer)
   MSG_WAITALL 
    (integer)
   MSG_PEEK 
    (integer)
   MSG_DONTROUTE 
    (integer)
   MSG_EOR 
    (integer)
   MSG_EOF 
    (integer)
   SO_DEBUG 
    (integer)
   SO_REUSEADDR 
    (integer)
   SO_REUSEPORT 
    (integer)
   SO_REUSEPORT socket option: this
     includes Mac OS X and FreeBSD, but does not include Linux or Windows.
    
   SO_KEEPALIVE 
    (integer)
   SO_DONTROUTE 
    (integer)
   SO_LINGER 
    (integer)
   SO_BROADCAST 
    (integer)
   SO_OOBINLINE 
    (integer)
   SO_SNDBUF 
    (integer)
   SO_RCVBUF 
    (integer)
   SO_SNDLOWAT 
    (integer)
   SO_RCVLOWAT 
    (integer)
   SO_SNDTIMEO 
    (integer)
   SO_RCVTIMEO 
    (integer)
   SO_TYPE 
    (integer)
   SO_ERROR 
    (integer)
   TCP_NODELAY 
    (integer)
   SOL_SOCKET 
    (integer)
   PHP_NORMAL_READ 
    (integer)
   PHP_BINARY_READ 
    (integer)
   SOL_TCP 
    (integer)
   SOL_UDP 
    (integer)
   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 
    (integer)
   SOCKET_EBADF 
    (integer)
   SOCKET_EACCES 
    (integer)
   SOCKET_EFAULT 
    (integer)
   SOCKET_EINVAL 
    (integer)
   SOCKET_EMFILE 
    (integer)
   SOCKET_ENAMETOOLONG 
    (integer)
   SOCKET_ENOTEMPTY 
    (integer)
   SOCKET_ELOOP 
    (integer)
   SOCKET_EWOULDBLOCK 
    (integer)
   SOCKET_EREMOTE 
    (integer)
   SOCKET_EUSERS 
    (integer)
   SOCKET_ENOTSOCK 
    (integer)
   SOCKET_EDESTADDRREQ 
    (integer)
   SOCKET_EMSGSIZE 
    (integer)
   SOCKET_EPROTOTYPE 
    (integer)
   SOCKET_EPROTONOSUPPORT 
    (integer)
   SOCKET_ESOCKTNOSUPPORT 
    (integer)
   SOCKET_EOPNOTSUPP 
    (integer)
   SOCKET_EPFNOSUPPORT 
    (integer)
   SOCKET_EAFNOSUPPORT 
    (integer)
   SOCKET_EADDRNOTAVAIL 
    (integer)
   SOCKET_ENETDOWN 
    (integer)
   SOCKET_ENETUNREACH 
    (integer)
   SOCKET_ENETRESET 
    (integer)
   SOCKET_ECONNABORTED 
    (integer)
   SOCKET_ECONNRESET 
    (integer)
   SOCKET_ENOBUFS 
    (integer)
   SOCKET_EISCONN 
    (integer)
   SOCKET_ENOTCONN 
    (integer)
   SOCKET_ESHUTDOWN 
    (integer)
   SOCKET_ETIMEDOUT 
    (integer)
   SOCKET_ECONNREFUSED 
    (integer)
   SOCKET_EHOSTDOWN 
    (integer)
   SOCKET_EHOSTUNREACH 
    (integer)
   SOCKET_EALREADY 
    (integer)
   SOCKET_EINPROGRESS 
    (integer)
   The following constants are only defined under Windows.
SOCKET_ENOPROTOOPT 
    (integer)
   SOCKET_EADDRINUSE 
    (integer)
   SOCKET_ETOOMYREFS 
    (integer)
   SOCKET_EPROCLIM 
    (integer)
   SOCKET_EDUOT 
    (integer)
   SOCKET_ESTALE 
    (integer)
   SOCKET_EDISCON 
    (integer)
   SOCKET_SYSNOTREADY 
    (integer)
   SOCKET_VERNOTSUPPORTED 
    (integer)
   SOCKET_NOTINITIALISED 
    (integer)
   SOCKET_HOST_NOT_FOUND 
    (integer)
   SOCKET_TRY_AGAIN 
    (integer)
   SOCKET_NO_RECOVERY 
    (integer)
   SOCKET_NO_DATA 
    (integer)
   SOCKET_NO_ADDRESS 
    (integer)
   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 
    (integer)
   SOCKET_ENOENT 
    (integer)
   SOCKET_EIO 
    (integer)
   SOCKET_ENXIO 
    (integer)
   SOCKET_E2BIG 
    (integer)
   SOCKET_EAGAIN 
    (integer)
   SOCKET_ENOMEM 
    (integer)
   SOCKET_ENOTBLK 
    (integer)
   SOCKET_EBUSY 
    (integer)
   SOCKET_EEXIST 
    (integer)
   SOCKET_EXDEV 
    (integer)
   SOCKET_ENODEV 
    (integer)
   SOCKET_ENOTDIR 
    (integer)
   SOCKET_EISDIR 
    (integer)
   SOCKET_ENFILE 
    (integer)
   SOCKET_ENOTTY 
    (integer)
   SOCKET_ENOSPC 
    (integer)
   SOCKET_ESPIPE 
    (integer)
   SOCKET_EROFS 
    (integer)
   SOCKET_EMLINK 
    (integer)
   SOCKET_EPIPE 
    (integer)
   SOCKET_ENOLCK 
    (integer)
   SOCKET_ENOSYS 
    (integer)
   SOCKET_ENOMSG 
    (integer)
   SOCKET_EIDRM 
    (integer)
   SOCKET_ECHRNG 
    (integer)
   SOCKET_EL2NSYNC 
    (integer)
   SOCKET_EL3HLT 
    (integer)
   SOCKET_EL3RST 
    (integer)
   SOCKET_ELNRNG 
    (integer)
   SOCKET_EUNATCH 
    (integer)
   SOCKET_ENOCSI 
    (integer)
   SOCKET_EL2HLT 
    (integer)
   SOCKET_EBADE 
    (integer)
   SOCKET_EBADR 
    (integer)
   SOCKET_EXFULL 
    (integer)
   SOCKET_ENOANO 
    (integer)
   SOCKET_EBADRQC 
    (integer)
   SOCKET_EBADSLT 
    (integer)
   SOCKET_ENOSTR 
    (integer)
   SOCKET_ENODATA 
    (integer)
   SOCKET_ETIME 
    (integer)
   SOCKET_ENOSR 
    (integer)
   SOCKET_ENONET 
    (integer)
   SOCKET_ENOLINK 
    (integer)
   SOCKET_EADV 
    (integer)
   SOCKET_ESRMNT 
    (integer)
   SOCKET_ECOMM 
    (integer)
   SOCKET_EPROTO 
    (integer)
   SOCKET_EMULTIHOP 
    (integer)
   SOCKET_EBADMSG 
    (integer)
   SOCKET_ENOTUNIQ 
    (integer)
   SOCKET_EBADFD 
    (integer)
   SOCKET_EREMCHG 
    (integer)
   SOCKET_ERESTART 
    (integer)
   SOCKET_ESTRPIPE 
    (integer)
   SOCKET_EPROTOOPT 
    (integer)
   SOCKET_ADDRINUSE 
    (integer)
   SOCKET_ETOOMANYREFS 
    (integer)
   SOCKET_EISNAM 
    (integer)
   SOCKET_EREMOTEIO 
    (integer)
   SOCKET_EDQUOT 
    (integer)
   SOCKET_ENOMEDIUM 
    (integer)
   SOCKET_EMEDIUMTYPE 
    (integer)