From 34f86754a20ad1a796430ee9483fce93bc30dfa2 Mon Sep 17 00:00:00 2001
From: Mark Stapp <mjs@voltanet.io>
Date: Thu, 2 Apr 2020 09:29:36 -0400
Subject: [PATCH] lib: add backup nexthop/nhlfe to zapi label messages

Add backup nexthops/nhlfes to the zapi messages used
to convey LSPs to zebra.

Signed-off-by: Mark Stapp <mjs@voltanet.io>
---
 lib/zclient.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 lib/zclient.h |  7 ++++++-
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/lib/zclient.c b/lib/zclient.c
index be2c4e54a0..fe0cd3ce27 100644
--- a/lib/zclient.c
+++ b/lib/zclient.c
@@ -2811,6 +2811,27 @@ int zapi_labels_encode(struct stream *s, int cmd, struct zapi_labels *zl)
 			return -1;
 	}
 
+	if (CHECK_FLAG(zl->message, ZAPI_LABELS_HAS_BACKUPS)) {
+
+		if (zl->backup_nexthop_num > MULTIPATH_NUM) {
+			flog_err(
+				EC_LIB_ZAPI_ENCODE,
+				"%s: label %u: can't encode %u nexthops (maximum is %u)",
+				__func__, zl->local_label, zl->nexthop_num,
+				MULTIPATH_NUM);
+			return -1;
+		}
+		stream_putw(s, zl->backup_nexthop_num);
+
+		for (int i = 0; i < zl->backup_nexthop_num; i++) {
+			znh = &zl->backup_nexthops[i];
+
+			if (zapi_nexthop_encode(s, znh, 0) < 0)
+				return -1;
+		}
+
+	}
+
 	/* Put length at the first point of the stream. */
 	stream_putw_at(s, 0, stream_get_endp(s));
 
@@ -2885,6 +2906,28 @@ int zapi_labels_decode(struct stream *s, struct zapi_labels *zl)
 			return -1;
 	}
 
+	if (CHECK_FLAG(zl->message, ZAPI_LABELS_HAS_BACKUPS)) {
+		STREAM_GETW(s, zl->backup_nexthop_num);
+
+		if (zl->backup_nexthop_num > MULTIPATH_NUM) {
+			flog_warn(
+				EC_LIB_ZAPI_ENCODE,
+				"%s: Prefix %pFX has %d backup nexthops, but we can only use the first %d",
+				__func__, &zl->route.prefix,
+				zl->backup_nexthop_num,	MULTIPATH_NUM);
+		}
+
+		zl->backup_nexthop_num = MIN(MULTIPATH_NUM,
+					     zl->backup_nexthop_num);
+
+		for (int i = 0; i < zl->backup_nexthop_num; i++) {
+			znh = &zl->backup_nexthops[i];
+
+			if (zapi_nexthop_decode(s, znh, 0) < 0)
+				return -1;
+		}
+	}
+
 	return 0;
 stream_failure:
 	return -1;
diff --git a/lib/zclient.h b/lib/zclient.h
index 4ada064623..92ac017e80 100644
--- a/lib/zclient.h
+++ b/lib/zclient.h
@@ -484,7 +484,8 @@ struct zapi_route {
 
 struct zapi_labels {
 	uint8_t message;
-#define ZAPI_LABELS_FTN      0x01
+#define ZAPI_LABELS_FTN           0x01
+#define ZAPI_LABELS_HAS_BACKUPS   0x02
 	enum lsp_types_t type;
 	mpls_label_t local_label;
 	struct {
@@ -495,6 +496,10 @@ struct zapi_labels {
 
 	uint16_t nexthop_num;
 	struct zapi_nexthop nexthops[MULTIPATH_NUM];
+
+	/* Backup nexthops, if present */
+	uint16_t backup_nexthop_num;
+	struct zapi_nexthop backup_nexthops[MULTIPATH_NUM];
 };
 
 struct zapi_pw {