add IP_RECVDSTPORT; ok jmc, beck

1 files changed, 29 insertions, 2 deletions

diff --git a/share/man/man4/ip.4 b/share/man/man4/ip.4
index c06268d8e86..d460456924a 100644
--- a/share/man/man4/ip.4
+++ b/share/man/man4/ip.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ip.4,v 1.27 2008/03/14 15:16:06 jmc Exp $
+.\"	$OpenBSD: ip.4,v 1.28 2008/05/09 08:16:35 markus Exp $
 .\"	$NetBSD: ip.4,v 1.3 1994/11/30 16:22:19 jtc Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"     @(#)ip.4	8.2 (Berkeley) 11/30/93
 .\"
-.Dd $Mdocdate: March 14 2008 $
+.Dd $Mdocdate: May 9 2008 $
 .Dt IP 4
 .Os
 .Sh NAME
@@ -139,6 +139,33 @@ cmsg_type = IP_RECVDSTADDR
 .Ed
 .Pp
 If the
+.Dv IP_RECVDSTPORT
+option is enabled on a
+.Dv SOCK_DGRAM
+socket,
+the
+.Xr recvmsg 2
+call will return the destination
+port for a
+.Tn UDP
+datagram.
+The
+.Va msg_control
+field in the
+.Vt msghdr
+structure points to a buffer that contains a
+.Vt cmsghdr
+structure followed by the port in 16-bit network byte order.
+The
+.Vt cmsghdr
+fields have the following values:
+.Bd -literal -offset indent
+cmsg_len = CMSG_LEN(sizeof(u_int16_t))
+cmsg_level = IPPROTO_IP
+cmsg_type = IP_RECVDSTPORT
+.Ed
+.Pp
+If the
 .Dv IP_RECVTTL
 option is enabled on a
 .Dv SOCK_DGRAM