From 4e1ef7984f8cd9372c63770fd97e925a58dfb1de Mon Sep 17 00:00:00 2001
From: haesbaert <>
Date: Sat, 7 Jul 2012 15:33:02 +0000
Subject: Allow UDP server to receive datagrams from multiple socket pairs with
 -k flag. Prompted by a question from dsp at 2f30 dot org, diff from Lazarom
 Koromil with a few tweaks by me, many thanks.

ok mikeb@ nicm@ haesbaert@
---
 src/usr.bin/nc/nc.1     |  8 ++++++--
 src/usr.bin/nc/netcat.c | 16 +++++++++++-----
 2 files changed, 17 insertions(+), 7 deletions(-)

(limited to 'src/usr.bin/nc')

diff --git a/src/usr.bin/nc/nc.1 b/src/usr.bin/nc/nc.1
index 75d1437580..232b6f5b6e 100644
--- a/src/usr.bin/nc/nc.1
+++ b/src/usr.bin/nc/nc.1
@@ -1,4 +1,4 @@
-.\"     $OpenBSD: nc.1,v 1.60 2012/02/07 12:11:43 lum Exp $
+.\"     $OpenBSD: nc.1,v 1.61 2012/07/07 15:33:02 haesbaert Exp $
 .\"
 .\" Copyright (c) 1996 David Sacerdote
 .\" All rights reserved.
@@ -25,7 +25,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: February 7 2012 $
+.Dd $Mdocdate: July 7 2012 $
 .Dt NC 1
 .Os
 .Sh NAME
@@ -119,6 +119,10 @@ is completed.
 It is an error to use this option without the
 .Fl l
 option.
+When used together with the
+.Fl u
+option, the server socket is not connected and it can receive UDP datagrams from
+multiple hosts.
 .It Fl l
 Used to specify that
 .Nm
diff --git a/src/usr.bin/nc/netcat.c b/src/usr.bin/nc/netcat.c
index 4bef71a7ca..a034bbab8c 100644
--- a/src/usr.bin/nc/netcat.c
+++ b/src/usr.bin/nc/netcat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: netcat.c,v 1.108 2012/07/07 09:36:30 haesbaert Exp $ */
+/* $OpenBSD: netcat.c,v 1.109 2012/07/07 15:33:02 haesbaert Exp $ */
 /*
  * Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
  *
@@ -345,11 +345,17 @@ main(int argc, char *argv[])
 			if (s < 0)
 				err(1, NULL);
 			/*
-			 * For UDP, we will use recvfrom() initially
-			 * to wait for a caller, then use the regular
-			 * functions to talk to the caller.
+			 * For UDP and -k, don't connect the socket, let it
+			 * receive datagrams from multiple socket pairs.
 			 */
-			if (uflag) {
+			if (uflag && kflag)
+				readwrite(s);
+			/*
+			 * For UDP and not -k, we will use recvfrom() initially
+			 * to wait for a caller, then use the regular functions
+			 * to talk to the caller.
+			 */
+			else if (uflag && !kflag) {
 				int rv, plen;
 				char buf[16384];
 				struct sockaddr_storage z;
-- 
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