Portability: POSIXize some of inet's error codes

include/errno.h

@@ -79,12 +79,12 @@ extern int errno;		  /* place where the error numbers go */
 
 /* The following errors relate to networking. */
 #define EPACKSIZE     (_SIGN 50)  /* invalid packet size for some protocol */
-#define EOUTOFBUFS    (_SIGN 51)  /* not enough buffers left */
+#define ENOBUFS       (_SIGN 51)  /* not enough buffers left */
 #define EBADIOCTL     (_SIGN 52)  /* illegal ioctl for device */
 #define EBADMODE      (_SIGN 53)  /* badmode in ioctl */
 #define EWOULDBLOCK   (_SIGN 54)  /* call would block on nonblocking socket */
-#define EBADDEST      (_SIGN 55)  /* not a valid destination address */
-#define EDSTNOTRCH    (_SIGN 56)  /* destination not reachable */
+#define ENETUNREACH   (_SIGN 55)  /* network unreachable */
+#define EHOSTUNREACH  (_SIGN 56)  /* host unreachable */
 #define EISCONN	      (_SIGN 57)  /* already connected */
 #define EADDRINUSE    (_SIGN 58)  /* address in use */
 #define ECONNREFUSED  (_SIGN 59)  /* connection refused */
@@ -105,6 +105,7 @@ extern int errno;		  /* place where the error numbers go */
 #define ENOTSOCK      (_SIGN 74)  /* Socket operation on non-socket */
 #define ENOPROTOOPT   (_SIGN 75)  /* Protocol not available */
 #define EOPNOTSUPP    (_SIGN 76)  /* Operation not supported */
+#define ENETDOWN      (_SIGN 77)  /* network is down */
 
 /* The following are not POSIX errors, but they can still happen. 
  * All of these are generated by the kernel and relate to message passing.