This commit implements the SO_USER_COOKIE socket option, which lets

you tag a socket with an uint32_t value. The cookie can then be
used by the kernel for various purposes, e.g. setting the skipto
rule or pipe number in ipfw (this is the reason SO_USER_COOKIE has
been implemented; however there is nothing ipfw-specific in its
implementation).

The ipfw-related code that uses the optopn will be committed separately.

This change adds a field to 'struct socket', but the struct is not
part of any driver or userland-visible ABI so the change should be
harmless.

See the discussion at
http://lists.freebsd.org/pipermail/freebsd-ipfw/2009-October/004001.html

Idea and code from Paul Joe, small modifications and manpage
changes by myself.

Submitted by:	Paul Joe
MFC after:	1 week

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
index 6d6578b68abe..94c3b24e5c3e 100644
--- a/sys/sys/socketvar.h
+++ b/sys/sys/socketvar.h
@@ -117,7 +117,14 @@ struct socket {
 		void	*so_accept_filter_arg;	/* saved filter args */
 		char	*so_accept_filter_str;	/* saved user args */
 	} *so_accf;
+	/*
+	 * so_fibnum, so_user_cookie and friends can be used to attach
+	 * some user-specified metadata to a socket, which then can be
+	 * used by the kernel for various actions.
+	 * so_user_cookie is used by ipfw/dummynet.
+	 */
 	int so_fibnum;		/* routing domain for this socket */
+	uint32_t so_user_cookie;
 };
 
 /*