This is a bit long, but personally I prefer to use the standard C defines in my code.
<?php
define('ENOTSOCK',      88);    /* Socket operation on non-socket */
define('EDESTADDRREQ',  89);    /* Destination address required */
define('EMSGSIZE',      90);    /* Message too long */
define('EPROTOTYPE',    91);    /* Protocol wrong type for socket */
define('ENOPROTOOPT',   92);    /* Protocol not available */
define('EPROTONOSUPPORT', 93);  /* Protocol not supported */
define('ESOCKTNOSUPPORT', 94);  /* Socket type not supported */
define('EOPNOTSUPP',    95);    /* Operation not supported on transport endpoint */
define('EPFNOSUPPORT',  96);    /* Protocol family not supported */
define('EAFNOSUPPORT',  97);    /* Address family not supported by protocol */
define('EADDRINUSE',    98);    /* Address already in use */
define('EADDRNOTAVAIL', 99);    /* Cannot assign requested address */
define('ENETDOWN',      100);   /* Network is down */
define('ENETUNREACH',   101);   /* Network is unreachable */
define('ENETRESET',     102);   /* Network dropped connection because of reset */
define('ECONNABORTED',  103);   /* Software caused connection abort */
define('ECONNRESET',    104);   /* Connection reset by peer */
define('ENOBUFS',       105);   /* No buffer space available */
define('EISCONN',       106);   /* Transport endpoint is already connected */
define('ENOTCONN',      107);   /* Transport endpoint is not connected */
define('ESHUTDOWN',     108);   /* Cannot send after transport endpoint shutdown */
define('ETOOMANYREFS',  109);   /* Too many references: cannot splice */
define('ETIMEDOUT',     110);   /* Connection timed out */
define('ECONNREFUSED',  111);   /* Connection refused */
define('EHOSTDOWN',     112);   /* Host is down */
define('EHOSTUNREACH',  113);   /* No route to host */
define('EALREADY',      114);   /* Operation already in progress */
define('EINPROGRESS',   115);   /* Operation now in progress */
define('EREMOTEIO',     121);   /* Remote I/O error */
define('ECANCELED',     125);   /* Operation Canceled */
?>