In the splnet(9) times netgraph(4) was synchronous and if a message

had been replied, the reply was always delivered to the originator
synchronously.

With introduction of netgraph item callbacks and a wait channel with
mutex in ng_socket(4), we have fixed the problem with ngctl(8) returning
earlier than the command has been proceeded by target node. But still
ngctl(8) can return prior to the reply has arrived to its node.

To fix this:
 - Introduce a new flag for netgraph(4) messages - NGM_HASREPLY.
   This flag is or'ed with message like NGM_READONLY.
 - In netgraph userland library if we have sent a message with
   NGM_HASREPLY flag, then select(2) until reply comes.
 - Mark appropriate generic commands with NGM_HASREPLY flag,
   gathering them into one enum {}. Bump generic cookie.

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/libnetgraph/msg.c b/lib/libnetgraph/msg.c
index cca9573..8b4ca06 100644
--- a/lib/libnetgraph/msg.c
+++ b/lib/libnetgraph/msg.c
@@ -232,6 +232,22 @@ NgDeliverMsg(int cs, const char *path,
 		goto done;
 	}
 
+	/* Wait for reply if there should be one. */
+	if (msg->header.cmd & NGM_HASREPLY) {
+		fd_set rfds;
+		int n;
+
+		FD_ZERO(&rfds);
+		FD_SET(cs, &rfds);
+		n = select(cs + 1, &rfds, NULL, NULL, NULL);
+		if (n == -1) {
+			errnosv = errno;
+			if (_gNgDebugLevel >= 1)
+				NGLOG("select");
+			rtn = -1;
+		}
+	}
+
 done:
 	/* Done */
 	free(buf);		/* OK if buf is NULL */