Update the sosplice(9) man page with UDP socket splicing.

help and OK jmc@

1 files changed, 30 insertions, 7 deletions

diff --git a/share/man/man9/sosplice.9 b/share/man/man9/sosplice.9
index 0c74f53a91d..e00bc483438 100644
--- a/share/man/man9/sosplice.9
+++ b/share/man/man9/sosplice.9
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: sosplice.9,v 1.4 2013/01/17 16:04:58 bluhm Exp $
+.\"	$OpenBSD: sosplice.9,v 1.5 2013/01/17 22:55:24 bluhm Exp $
 .\"
 .\" Copyright (c) 2011-2013 Alexander Bluhm <bluhm@openbsd.org>
 .\"
@@ -139,8 +139,22 @@ length and the space in the drain's send socket buffer.
 Up to this amount of data is taken out of the source's receive
 socket buffer.
 .Pp
+For atomic protocols, either one complete packet is taken out, or
+nothing is taken at all if:
+the packet is bigger than the the drain's send buffer size, in which
+case the splicing gets aborted with an
+.Er EMSGSIZE
+error;
+the packet does not fit into the drain's current send buffer space,
+in which case it is left in the source's receive buffer for later
+processing;
+or the maximum splice length is located within a packet, in which
+case splicing gets dissolved like a short splice.
+All address or control mbufs associated with the taken packet are
+dropped.
+.Pp
 If the maximum splice length has been reached, an mbuf may get
-split.
+split for non-atomic protocols.
 Otherwise an mbuf is either moved completely to the send buffer or
 left in the receive buffer for later processing.
 If SO_OOBINLINE is set, out-of-band data will get moved as such
@@ -150,6 +164,10 @@ If that fails and the drain socket cannot send anymore, an
 .Er EPIPE
 error is set on the source socket.
 .Pp
+For packet oriented protocols
+.Fn somove
+iterates over the next packet queue.
+.Pp
 If a maximum splice length was specified and at least this amount
 of data has been received from the drain socket, splicing gets
 dissolved.
@@ -208,8 +226,11 @@ The given maximum value
 .Fa max
 is negative.
 .It Bq Er ENOTCONN
-The source or the drain socket is neither connected nor in the
-process of connecting to a peer.
+The source socket requires a connection and is neither connected
+nor in the process of connecting to a peer.
+.It Bq Er ENOTCONN
+The drain socket is neither connected nor in the process of connecting
+to a peer.
 .It Bq Er ENOTSOCK
 The given file descriptor
 .Fa fd
@@ -220,7 +241,7 @@ The source or the drain socket is a listen socket.
 The source socket's protocol layer does not have the
 .Dv PR_SPLICE
 flag set.
-At the moment only TCP supports socket splicing.
+Only TCP and UDP socket splicing is supported.
 .It Bq Er EPROTONOSUPPORT
 The drain socket's protocol does not have the same
 .Fa pr_usrreq
@@ -234,8 +255,10 @@ locked.
 .Xr options 4 ,
 .Xr timeout 9
 .Sh HISTORY
-Socket splicing first appeared in
-.Ox 4.9 .
+Socket splicing for TCP first appeared in
+.Ox 4.9 ;
+support for UDP was added in
+.Ox 5.3 .
 .Sh AUTHORS
 .An -nosplit
 The idea for socket splicing originally came from