Date: Tue, 22 Jan 2013 15:28:18 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-net@freebsd.org Cc: Lawrence Stewart <lstewart@freebsd.org> Subject: Re: [PATCH] Don't imply TCP and UDP socket options are bitmasks Message-ID: <201301221528.18388.jhb@freebsd.org> In-Reply-To: <50FE5473.7000807@freebsd.org> References: <201301141550.13577.jhb@freebsd.org> <201301151416.07231.jhb@freebsd.org> <50FE5473.7000807@freebsd.org>
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On Tuesday, January 22, 2013 3:57:23 am Lawrence Stewart wrote:
> On 01/16/13 06:16, John Baldwin wrote:
> > On Tuesday, January 15, 2013 3:49:33 am Lawrence Stewart wrote:
> >> On 01/15/13 07:50, John Baldwin wrote:
> >>> The constants used for TCP and UDP socket options (TCP_NODELAY, etc.) are
> >>> currently defined as hex values that are individual bits. However, socket
> >>> options are never masked together, they are used as a simple enumeration of
> >>> discrete values. Using a bitmask forces us to run out of bits and makes it
> >>> harder for vendors to try to use a high range of values for local custom
> >>> options (hoping that they never conflict with a new option value added in
> >>> stock FreeBSD).
> >>
> >> Yup. Should we be explicitly #defining the boundary between "bits
> >> reserved for FreeBSD" and "bits for private vendor use"?
> >
> > Oh, we could if you wanted. I'm using 0x1000 locally for both TCP and UDP,
> > but those are completely arbitrary values. Saner ones might be 0x8000000 if
> > we want to do that explicitly. We could perhaps just say that is true for all
> > socket option levels (that is, just define one SO_VENDOR constant or some such
> > but say it applies to all levels)?
>
> A single SO_VENDOR applied to all levels sounds good to me.
Ok, how about this for wording:
Index: sys/socket.h
===================================================================
--- socket.h (revision 245742)
+++ socket.h (working copy)
@@ -143,6 +143,15 @@ typedef __uid_t uid_t;
#endif
/*
+ * Space reserved for new socket options added by third-party vendors.
+ * This range applies to all socket option levels. New socket options
+ * in FreeBSD should always use an option value less than SO_VENDOR.
+ */
+#if __BSD_VISIBLE
+#define SO_VENDOR 0x80000000
+#endif
+
+/*
* Structure used for manipulating linger option.
*/
struct linger {
--
John Baldwin
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