[PATCH] Don't imply TCP and UDP socket options are bitmasks

[John Baldwin]

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