bfdd: send replay request on zebra connection

This will make `bfdd` synchronize with its client when zebra dies or
bfdd is restarted.

Signed-off-by: Rafael Zalamena <rzalamena@opensourcerouting.org>

2 files changed, 48 insertions, 7 deletions

diff --git a/bfdd/ptm_adapter.c b/bfdd/ptm_adapter.c
index 5e79be91f..28e332626 100644
--- a/bfdd/ptm_adapter.c
+++ b/bfdd/ptm_adapter.c
@@ -180,6 +180,9 @@ int ptm_bfd_notify(struct bfd_session *bs)
 	/* TODO: VRF handling */
 	zclient_create_header(msg, ZEBRA_BFD_DEST_REPLAY, VRF_DEFAULT);
 
+	/* This header will be handled by `zebra_ptm.c`. */
+	stream_putl(msg, ZEBRA_INTERFACE_BFD_DEST_UPDATE);
+
 	/* NOTE: Interface is a shortcut to avoid comparing source address. */
 	stream_putl(msg, bs->ifindex);
 
@@ -515,6 +518,22 @@ stream_failure:
 	return -1;
 }
 
+static void bfdd_zebra_connected(struct zclient *zc)
+{
+	struct stream *msg = zc->obuf;
+
+	/*
+	 * The replay is an empty message just to trigger client daemons
+	 * configuration replay.
+	 */
+	stream_reset(msg);
+	zclient_create_header(msg, ZEBRA_BFD_DEST_REPLAY, VRF_DEFAULT);
+	stream_putl(msg, ZEBRA_BFD_DEST_REPLAY);
+	stream_putw_at(msg, 0, stream_get_endp(msg));
+
+	zclient_send_message(zclient);
+}
+
 void bfdd_zclient_init(struct zebra_privs_t *bfdd_priv)
 {
 	zclient = zclient_new_notify(master, &zclient_options_default);
@@ -527,6 +546,9 @@ void bfdd_zclient_init(struct zebra_privs_t *bfdd_priv)
 	 * avoid having to create too many handlers.
 	 */
 	zclient->bfd_dest_replay = bfdd_replay;
+
+	/* Send replay request on zebra connect. */
+	zclient->zebra_connected = bfdd_zebra_connected;
 }
 
 void bfdd_zclient_stop(void)
diff --git a/zebra/zebra_ptm.c b/zebra/zebra_ptm.c
index 5a69568fe..76e427570 100644
--- a/zebra/zebra_ptm.c
+++ b/zebra/zebra_ptm.c
@@ -1468,6 +1468,7 @@ void zebra_ptm_bfd_dst_replay(ZAPI_HANDLER_ARGS)
 {
 	struct stream *msgc;
 	size_t zmsglen, zhdrlen;
+	uint32_t cmd;
 
 	/*
 	 * NOTE:
@@ -1480,6 +1481,21 @@ void zebra_ptm_bfd_dst_replay(ZAPI_HANDLER_ARGS)
 			   zebra_route_string(client->proto), hdr->length);
 
 	/*
+	 * Client messages must be re-routed, otherwise do the `bfdd`
+	 * special treatment.
+	 */
+	if (client->proto != ZEBRA_ROUTE_BFD) {
+		_zebra_ptm_reroute(client, msg, ZEBRA_BFD_DEST_REPLAY);
+		return;
+	}
+
+	/* Figure out if this is an DEST_UPDATE or DEST_REPLAY. */
+	if (stream_getl2(msg, &cmd) == false) {
+		zlog_err("%s: expected at least 4 bytes (command)", __func__);
+		return;
+	}
+
+	/*
 	 * Don't modify message in the zebra API. In order to do that we
 	 * need to allocate a new message stream and copy the message
 	 * provided by zebra.
@@ -1491,16 +1507,19 @@ void zebra_ptm_bfd_dst_replay(ZAPI_HANDLER_ARGS)
 	}
 
 	/* Calculate our header size plus the message contents. */
-	zhdrlen = ZEBRA_HEADER_SIZE;
-	zmsglen = msg->endp - msg->getp;
-	memcpy(msgc->data + zhdrlen, msg->data + msg->getp, zmsglen);
+	if (cmd != ZEBRA_BFD_DEST_REPLAY) {
+		zhdrlen = ZEBRA_HEADER_SIZE;
+		zmsglen = msg->endp - msg->getp;
+		memcpy(msgc->data + zhdrlen, msg->data + msg->getp, zmsglen);
 
-	zclient_create_header(msgc, ZEBRA_INTERFACE_BFD_DEST_UPDATE,
-			      zvrf_id(zvrf));
+		zclient_create_header(msgc, cmd, zvrf_id(zvrf));
+
+		msgc->getp = 0;
+		msgc->endp = zhdrlen + zmsglen;
+	} else
+		zclient_create_header(msgc, cmd, zvrf_id(zvrf));
 
 	/* Update the data pointers. */
-	msgc->getp = 0;
-	msgc->endp = zhdrlen + zmsglen;
 	stream_putw_at(msgc, 0, stream_get_endp(msgc));
 
 	zebra_ptm_send_clients(msgc);