From 75e7ef74dfc12e01b1ef4706110d238639e04543 Mon Sep 17 00:00:00 2001
From: Lutz Donnerhacke <donner@FreeBSD.org>
Date: Sun, 17 Jan 2021 21:35:28 +0100
Subject: [PATCH] netgraph/ng_source: Allow ng_source to inject into any
 netgraph network

PR:		240530
Reviewed by:	kp
Approved by:	kp (mentor)
MFC after:	1 month
Differential Revision: https://reviews.freebsd.org/D21968
---
 share/man/man4/ng_source.4 | 11 +++++++++--
 sys/netgraph/ng_source.c   |  4 ++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/share/man/man4/ng_source.4 b/share/man/man4/ng_source.4
index 5205bc41e15d..87b235bda2c8 100644
--- a/share/man/man4/ng_source.4
+++ b/share/man/man4/ng_source.4
@@ -32,7 +32,7 @@
 .\" Author: Dave Chapeskie
 .\" $FreeBSD$
 .\"
-.Dd March 1, 2007
+.Dd January 18, 2021
 .Dt NG_SOURCE 4
 .Os
 .Sh NAME
@@ -91,7 +91,14 @@ should be turned off on
 .Xr ng_ether 4
 node manually.
 .Pp
-Once interface is configured, upon receipt of a
+If the node is connected to a netgraph network, which does not
+terminate in a real
+.Xr ng_ether 4
+interface, limit the packet injection rate explicitly with the
+.Va NGM_SOURCE_SETPPS
+control message.
+.Pp
+Upon receipt of a
 .Dv NGM_SOURCE_START
 control message the node starts sending
 the previously queued packets out the
diff --git a/sys/netgraph/ng_source.c b/sys/netgraph/ng_source.c
index da8f42381ac3..401548da65d0 100644
--- a/sys/netgraph/ng_source.c
+++ b/sys/netgraph/ng_source.c
@@ -683,8 +683,8 @@ ng_source_clr_data (sc_p sc)
 static int
 ng_source_start(sc_p sc, uint64_t packets)
 {
-	if (sc->output_ifp == NULL) {
-		printf("ng_source: start without iface configured\n");
+	if (sc->output_ifp == NULL && sc->stats.maxPps == 0) {
+		printf("ng_source: start without iface or pps configured\n");
 		return (ENXIO);
 	}