Document SO_PROTOCOL socket option.

Discussed with:	bz
Reviewed by:	glebius
MFC after:	2 weeks

1 files changed, 13 insertions, 2 deletions

diff --git a/lib/libc/sys/getsockopt.2 b/lib/libc/sys/getsockopt.2
index edd92c3..1e0d3f91 100644
--- a/lib/libc/sys/getsockopt.2
+++ b/lib/libc/sys/getsockopt.2
@@ -28,7 +28,7 @@
 .\"     @(#)getsockopt.2	8.4 (Berkeley) 5/2/95
 .\" $FreeBSD$
 .\"
-.Dd November 21, 2011
+.Dd February 26, 2012
 .Dt GETSOCKOPT 2
 .Os
 .Sh NAME
@@ -172,6 +172,8 @@ for the socket
 .It Dv SO_BINTIME Ta "enables reception of a timestamp with datagrams"
 .It Dv SO_ACCEPTCONN Ta "get listening status of the socket (get only)"
 .It Dv SO_TYPE Ta "get the type of the socket (get only)"
+.It Dv SO_PROTOCOL Ta "get the protocol number for the socket (get only)"
+.It Dv SO_PROTOTYPE Ta "SunOS alias for the Linux SO_PROTOCOL (get only)"
 .It Dv SO_ERROR Ta "get and clear error on the socket (get only)"
 .It Dv SO_SETFIB Ta "set the associated FIB (routing table) for the socket (set only)"
 .El
@@ -449,7 +451,10 @@ and for
 .Ed
 .Pp
 .Dv SO_ACCEPTCONN ,
-.Dv SO_TYPE
+.Dv SO_TYPE ,
+.Dv SO_PROTOCOL
+(and its alias
+.Dv SO_PROTOTYPE )
 and
 .Dv SO_ERROR
 are options used only with
@@ -463,6 +468,12 @@ system call was invoked on the socket.
 returns the type of the socket, such as
 .Dv SOCK_STREAM ;
 it is useful for servers that inherit sockets on startup.
+.Dv SO_PROTOCOL
+returns the protocol number for the socket, for
+.Dv AF_INET
+and
+.Dv AF_INET6
+address families.
 .Dv SO_ERROR
 returns any pending error on the socket and clears
 the error status.