35 files changed, 492 insertions, 136 deletions

diff --git a/lib/agg_table.h b/lib/agg_table.h
index f95fed6758..e98476f1b7 100644
--- a/lib/agg_table.h
+++ b/lib/agg_table.h
@@ -155,6 +155,16 @@ static inline struct agg_table *agg_get_table(struct agg_node *node)
 	return (struct agg_table *)route_table_get_info(node->table);
 }
 
+static inline const struct prefix *
+agg_node_get_prefix(const struct agg_node *node)
+{
+	return &node->p;
+}
+
+#ifdef _FRR_ATTRIBUTE_PRINTFRR
+#pragma FRR printfrr_ext "%pRN"  (struct agg_node *)
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/compiler.h b/lib/compiler.h
index e430925e69..217a60d888 100644
--- a/lib/compiler.h
+++ b/lib/compiler.h
@@ -305,7 +305,14 @@ extern "C" {
 #include <inttypes.h>
 
 #ifdef _FRR_ATTRIBUTE_PRINTFRR
-#define PRINTFRR(a, b) __attribute__((printfrr(a, b)))
+#define PRINTFRR(a, b) __attribute__((frr_format("frr_printf", a, b)))
+
+#undef PRIu64
+#undef PRId64
+#undef PRIx64
+#define PRIu64 "Lu"
+#define PRId64 "Ld"
+#define PRIx64 "Lx"
 
 #else /* !_FRR_ATTRIBUTE_PRINTFRR */
 #define PRINTFRR(a, b) __attribute__((format(printf, a, b)))
diff --git a/lib/frrlua.c b/lib/frrlua.c
index 26610556dc..9f9cf8c1f6 100644
--- a/lib/frrlua.c
+++ b/lib/frrlua.c
@@ -5,7 +5,7 @@
  * Copyright (C) 2016 Cumulus Networks, Inc.
  * Donald Sharp
  *
- * This file is part of FreeRangeRouting (FRR).
+ * This file is part of FRRouting (FRR).
  *
  * FRR is free software; you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
diff --git a/lib/frrlua.h b/lib/frrlua.h
index 374eb70311..40c7a67b89 100644
--- a/lib/frrlua.h
+++ b/lib/frrlua.h
@@ -5,7 +5,7 @@
  * Copyright (C) 2016 Cumulus Networks, Inc.
  * Donald Sharp
  *
- * This file is part of FreeRangeRouting (FRR).
+ * This file is part of FRRouting (FRR).
  *
  * FRR is free software; you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
diff --git a/lib/grammar_sandbox_main.c b/lib/grammar_sandbox_main.c
index 4bd8f5138a..5d3f6675a3 100644
--- a/lib/grammar_sandbox_main.c
+++ b/lib/grammar_sandbox_main.c
@@ -7,7 +7,7 @@
  * Copyright (C) 2016 Cumulus Networks, Inc.
  * Copyright (C) 2017 David Lamparter for NetDEF, Inc.
  *
- * This file is part of FreeRangeRouting (FRR).
+ * This file is part of FRRouting (FRR).
  *
  * FRR is free software; you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
diff --git a/lib/ipaddr.h b/lib/ipaddr.h
index c6372f1abb..cd7f79a04e 100644
--- a/lib/ipaddr.h
+++ b/lib/ipaddr.h
@@ -112,7 +112,7 @@ static inline void ipv4_to_ipv4_mapped_ipv6(struct in6_addr *in6,
 /*
  * convert an ipv4 mapped ipv6 address back to ipv4 address
  */
-static inline void ipv4_mapped_ipv6_to_ipv4(struct in6_addr *in6,
+static inline void ipv4_mapped_ipv6_to_ipv4(const struct in6_addr *in6,
 					    struct in_addr *in)
 {
 	memset(in, 0, sizeof(struct in_addr));
diff --git a/lib/log.c b/lib/log.c
index 2101e0225c..b3be5216aa 100644
--- a/lib/log.c
+++ b/lib/log.c
@@ -1228,59 +1228,47 @@ int proto_redistnum(int afi, const char *s)
 	return -1;
 }
 
-void zlog_hexdump(const void *mem, unsigned int len)
+void zlog_hexdump(const void *mem, size_t len)
 {
-	unsigned long i = 0;
-	unsigned int j = 0;
-	unsigned int columns = 8;
-	/*
-	 * 19 bytes for 0xADDRESS:
-	 * 24 bytes for data; 2 chars plus a space per data byte
-	 *  1 byte for space
-	 *  8 bytes for ASCII representation
-	 *  1 byte for a newline
-	 * =====================
-	 * 53 bytes per 8 bytes of data
-	 *  1 byte for null term
-	 */
-	size_t bs = ((len / 8) + 1) * 53 + 1;
-	char buf[bs];
-	char *s = buf;
-	const unsigned char *memch = mem;
-
-	memset(buf, 0, sizeof(buf));
-
-	for (i = 0; i < len + ((len % columns) ? (columns - len % columns) : 0);
-	     i++) {
-		/* print offset */
-		if (i % columns == 0)
-			s += snprintf(s, bs - (s - buf),
-				      "0x%016lx: ", (unsigned long)memch + i);
-
-		/* print hex data */
-		if (i < len)
-			s += snprintf(s, bs - (s - buf), "%02x ", memch[i]);
-
-		/* end of block, just aligning for ASCII dump */
-		else
-			s += snprintf(s, bs - (s - buf), "   ");
-
-		/* print ASCII dump */
-		if (i % columns == (columns - 1)) {
-			for (j = i - (columns - 1); j <= i; j++) {
-				/* end of block not really printing */
-				if (j >= len)
-					s += snprintf(s, bs - (s - buf), " ");
-				else if (isprint(memch[j]))
-					s += snprintf(s, bs - (s - buf), "%c",
-						      memch[j]);
-				else /* other char */
-					s += snprintf(s, bs - (s - buf), ".");
-			}
-			s += snprintf(s, bs - (s - buf), "\n");
+	char line[64];
+	const uint8_t *src = mem;
+	const uint8_t *end = src + len;
+
+	if (len == 0) {
+		zlog_debug("%016lx: (zero length / no data)", (long)src);
+		return;
+	}
+
+	while (src < end) {
+		struct fbuf fb = {
+			.buf = line,
+			.pos = line,
+			.len = sizeof(line),
+		};
+		const uint8_t *lineend = src + 8;
+		unsigned line_bytes = 0;
+
+		bprintfrr(&fb, "%016lx: ", (long)src);
+
+		while (src < lineend && src < end) {
+			bprintfrr(&fb, "%02x ", *src++);
+			line_bytes++;
+		}
+		if (line_bytes < 8)
+			bprintfrr(&fb, "%*s", (8 - line_bytes) * 3, "");
+
+		src -= line_bytes;
+		while (src < lineend && src < end && fb.pos < fb.buf + fb.len) {
+			uint8_t byte = *src++;
+
+			if (isprint(byte))
+				*fb.pos++ = byte;
+			else
+				*fb.pos++ = '.';
 		}
+
+		zlog_debug("%.*s", (int)(fb.pos - fb.buf), fb.buf);
 	}
-	zlog_debug("\n%s", buf);
 }
 
 const char *zlog_sanitize(char *buf, size_t bufsz, const void *in, size_t inlen)
diff --git a/lib/log.h b/lib/log.h
index 501da88a54..d79ad9f805 100644
--- a/lib/log.h
+++ b/lib/log.h
@@ -152,7 +152,7 @@ extern void zlog_backtrace_sigsafe(int priority, void *program_counter);
 extern size_t quagga_timestamp(int timestamp_precision /* # subsecond digits */,
 			       char *buf, size_t buflen);
 
-extern void zlog_hexdump(const void *mem, unsigned int len);
+extern void zlog_hexdump(const void *mem, size_t len);
 extern const char *zlog_sanitize(char *buf, size_t bufsz, const void *in,
 				 size_t inlen);
 
diff --git a/lib/mpls.c b/lib/mpls.c
index 759fe1206d..ac5792a686 100644
--- a/lib/mpls.c
+++ b/lib/mpls.c
@@ -79,7 +79,7 @@ int mpls_str2label(const char *label_str, uint8_t *num_labels,
 /*
  * Label to string conversion, labels in string separated by '/'.
  */
-char *mpls_label2str(uint8_t num_labels, mpls_label_t *labels, char *buf,
+char *mpls_label2str(uint8_t num_labels, const mpls_label_t *labels, char *buf,
 		     int len, int pretty)
 {
 	char label_buf[BUFSIZ];
diff --git a/lib/mpls.h b/lib/mpls.h
index 635ecc77a1..05cf2935e8 100644
--- a/lib/mpls.h
+++ b/lib/mpls.h
@@ -209,10 +209,13 @@ static inline char *label2str(mpls_label_t label, char *buf, size_t len)
 int mpls_str2label(const char *label_str, uint8_t *num_labels,
 		   mpls_label_t *labels);
 
+/* Generic string buffer for label-stack-to-str */
+#define MPLS_LABEL_STRLEN 1024
+
 /*
  * Label to string conversion, labels in string separated by '/'.
  */
-char *mpls_label2str(uint8_t num_labels, mpls_label_t *labels, char *buf,
+char *mpls_label2str(uint8_t num_labels, const mpls_label_t *labels, char *buf,
 		     int len, int pretty);
 
 #ifdef __cplusplus
diff --git a/lib/nexthop.c b/lib/nexthop.c
index e23f8b0792..0d239e091b 100644
--- a/lib/nexthop.c
+++ b/lib/nexthop.c
@@ -23,11 +23,9 @@
 #include "table.h"
 #include "memory.h"
 #include "command.h"
-#include "if.h"
 #include "log.h"
 #include "sockunion.h"
 #include "linklist.h"
-#include "thread.h"
 #include "prefix.h"
 #include "nexthop.h"
 #include "mpls.h"
@@ -155,7 +153,24 @@ static int _nexthop_cmp_no_labels(const struct nexthop *next1,
 	}
 
 	ret = _nexthop_source_cmp(next1, next2);
+	if (ret != 0)
+		goto done;
+
+	if (!CHECK_FLAG(next1->flags, NEXTHOP_FLAG_HAS_BACKUP) &&
+	    CHECK_FLAG(next2->flags, NEXTHOP_FLAG_HAS_BACKUP))
+		return -1;
+
+	if (CHECK_FLAG(next1->flags, NEXTHOP_FLAG_HAS_BACKUP) &&
+	    !CHECK_FLAG(next2->flags, NEXTHOP_FLAG_HAS_BACKUP))
+		return 1;
+
+	if (next1->backup_idx < next2->backup_idx)
+		return -1;
 
+	if (next1->backup_idx > next2->backup_idx)
+		return 1;
+
+done:
 	return ret;
 }
 
@@ -240,7 +255,7 @@ struct nexthop *nexthop_new(void)
 	 * The linux kernel does some weird stuff with adding +1 to
 	 * all nexthop weights it gets over netlink.
 	 * To handle this, just default everything to 1 right from
-	 * from the beggining so we don't have to special case
+	 * from the beginning so we don't have to special case
 	 * default weights in the linux netlink code.
 	 *
 	 * 1 should be a valid on all platforms anyway.
@@ -393,8 +408,8 @@ struct nexthop *nexthop_from_blackhole(enum blackhole_type bh_type)
 }
 
 /* Update nexthop with label information. */
-void nexthop_add_labels(struct nexthop *nexthop, enum lsp_types_t type,
-			uint8_t num_labels, mpls_label_t *label)
+void nexthop_add_labels(struct nexthop *nexthop, enum lsp_types_t ltype,
+			uint8_t num_labels, const mpls_label_t *labels)
 {
 	struct mpls_label_stack *nh_label;
 	int i;
@@ -402,23 +417,26 @@ void nexthop_add_labels(struct nexthop *nexthop, enum lsp_types_t type,
 	if (num_labels == 0)
 		return;
 
-	nexthop->nh_label_type = type;
+	/* Enforce limit on label stack size */
+	if (num_labels > MPLS_MAX_LABELS)
+		num_labels = MPLS_MAX_LABELS;
+
+	nexthop->nh_label_type = ltype;
+
 	nh_label = XCALLOC(MTYPE_NH_LABEL,
 			   sizeof(struct mpls_label_stack)
 				   + num_labels * sizeof(mpls_label_t));
 	nh_label->num_labels = num_labels;
 	for (i = 0; i < num_labels; i++)
-		nh_label->label[i] = *(label + i);
+		nh_label->label[i] = *(labels + i);
 	nexthop->nh_label = nh_label;
 }
 
 /* Free label information of nexthop, if present. */
 void nexthop_del_labels(struct nexthop *nexthop)
 {
-	if (nexthop->nh_label) {
-		XFREE(MTYPE_NH_LABEL, nexthop->nh_label);
-		nexthop->nh_label_type = ZEBRA_LSP_NONE;
-	}
+	XFREE(MTYPE_NH_LABEL, nexthop->nh_label);
+	nexthop->nh_label_type = ZEBRA_LSP_NONE;
 }
 
 const char *nexthop2str(const struct nexthop *nexthop, char *str, int size)
@@ -505,6 +523,7 @@ unsigned int nexthop_level(struct nexthop *nexthop)
 uint32_t nexthop_hash_quick(const struct nexthop *nexthop)
 {
 	uint32_t key = 0x45afe398;
+	uint32_t val;
 
 	key = jhash_3words(nexthop->type, nexthop->vrf_id,
 			   nexthop->nh_label_type, key);
@@ -534,8 +553,12 @@ uint32_t nexthop_hash_quick(const struct nexthop *nexthop)
 			key = jhash_1word(nexthop->nh_label->label[i], key);
 	}
 
-	key = jhash_2words(nexthop->ifindex,
-			   CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK),
+	val = 0;
+	if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_HAS_BACKUP))
+		val = (uint32_t)nexthop->backup_idx;
+
+	key = jhash_3words(nexthop->ifindex,
+			   CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK), val,
 			   key);
 
 	return key;
@@ -575,6 +598,7 @@ void nexthop_copy_no_recurse(struct nexthop *copy,
 	copy->type = nexthop->type;
 	copy->flags = nexthop->flags;
 	copy->weight = nexthop->weight;
+	copy->backup_idx = nexthop->backup_idx;
 	memcpy(&copy->gate, &nexthop->gate, sizeof(nexthop->gate));
 	memcpy(&copy->src, &nexthop->src, sizeof(nexthop->src));
 	memcpy(&copy->rmap_src, &nexthop->rmap_src, sizeof(nexthop->rmap_src));
diff --git a/lib/nexthop.h b/lib/nexthop.h
index 6710914e40..c4e88dd844 100644
--- a/lib/nexthop.h
+++ b/lib/nexthop.h
@@ -86,6 +86,8 @@ struct nexthop {
 					  * active one
 					  */
 #define NEXTHOP_FLAG_RNH_FILTERED  (1 << 5) /* rmap filtered, used by rnh */
+#define NEXTHOP_FLAG_HAS_BACKUP (1 << 6)    /* Backup nexthop index is set */
+
 #define NEXTHOP_IS_ACTIVE(flags)                                               \
 	(CHECK_FLAG(flags, NEXTHOP_FLAG_ACTIVE)                                \
 	 && !CHECK_FLAG(flags, NEXTHOP_FLAG_DUPLICATE))
@@ -116,15 +118,31 @@ struct nexthop {
 
 	/* Weight of the nexthop ( for unequal cost ECMP ) */
 	uint8_t weight;
+
+	/* Index of a corresponding backup nexthop in a backup list;
+	 * only meaningful if the HAS_BACKUP flag is set.
+	 */
+	uint8_t backup_idx;
 };
 
+/* Backup index value is limited */
+#define NEXTHOP_BACKUP_IDX_MAX 255
+
+/* Utility to append one nexthop to another. */
+#define NEXTHOP_APPEND(to, new)           \
+	do {                              \
+		(to)->next = (new);       \
+		(new)->prev = (to);       \
+		(new)->next = NULL;       \
+	} while (0)
+
 struct nexthop *nexthop_new(void);
 
 void nexthop_free(struct nexthop *nexthop);
 void nexthops_free(struct nexthop *nexthop);
 
-void nexthop_add_labels(struct nexthop *, enum lsp_types_t, uint8_t,
-			mpls_label_t *);
+void nexthop_add_labels(struct nexthop *nexthop, enum lsp_types_t ltype,
+			uint8_t num_labels, const mpls_label_t *labels);
 void nexthop_del_labels(struct nexthop *);
 
 /*
@@ -201,6 +219,10 @@ extern struct nexthop *nexthop_dup(const struct nexthop *nexthop,
 extern struct nexthop *nexthop_dup_no_recurse(const struct nexthop *nexthop,
 					      struct nexthop *rparent);
 
+#ifdef _FRR_ATTRIBUTE_PRINTFRR
+#pragma FRR printfrr_ext "%pNH"  (struct nexthop *)
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/nexthop_group.c b/lib/nexthop_group.c
index d660428bcd..8c3bbbdcd4 100644
--- a/lib/nexthop_group.c
+++ b/lib/nexthop_group.c
@@ -43,8 +43,12 @@ struct nexthop_hold {
 	char *intf;
 	char *labels;
 	uint32_t weight;
+	int backup_idx; /* Index of backup nexthop, if >= 0 */
 };
 
+/* Invalid/unset value for nexthop_hold's backup_idx */
+#define NHH_BACKUP_IDX_INVALID -1
+
 struct nexthop_group_hooks {
 	void (*new)(const char *name);
 	void (*add_nexthop)(const struct nexthop_group_cmd *nhg,
@@ -225,6 +229,10 @@ void nexthop_group_copy(struct nexthop_group *to,
 
 void nexthop_group_delete(struct nexthop_group **nhg)
 {
+	/* OK to call with NULL group */
+	if ((*nhg) == NULL)
+		return;
+
 	if ((*nhg)->nexthop)
 		nexthops_free((*nhg)->nexthop);
 
@@ -567,11 +575,36 @@ DEFUN_NOSH(no_nexthop_group, no_nexthop_group_cmd, "no nexthop-group NHGNAME",
 	return CMD_SUCCESS;
 }
 
+DEFPY(nexthop_group_backup, nexthop_group_backup_cmd,
+      "backup-group WORD$name",
+      "Specify a group name containing backup nexthops\n"
+      "The name of the backup group\n")
+{
+	VTY_DECLVAR_CONTEXT(nexthop_group_cmd, nhgc);
+
+	strlcpy(nhgc->backup_list_name, name, sizeof(nhgc->backup_list_name));
+
+	return CMD_SUCCESS;
+}
+
+DEFPY(no_nexthop_group_backup, no_nexthop_group_backup_cmd,
+      "no backup-group [WORD$name]",
+      NO_STR
+      "Clear group name containing backup nexthops\n"
+      "The name of the backup group\n")
+{
+	VTY_DECLVAR_CONTEXT(nexthop_group_cmd, nhgc);
+
+	nhgc->backup_list_name[0] = 0;
+
+	return CMD_SUCCESS;
+}
+
 static void nexthop_group_save_nhop(struct nexthop_group_cmd *nhgc,
 				    const char *nhvrf_name,
 				    const union sockunion *addr,
 				    const char *intf, const char *labels,
-				    const uint32_t weight)
+				    const uint32_t weight, int backup_idx)
 {
 	struct nexthop_hold *nh;
 
@@ -588,6 +621,8 @@ static void nexthop_group_save_nhop(struct nexthop_group_cmd *nhgc,
 
 	nh->weight = weight;
 
+	nh->backup_idx = backup_idx;
+
 	listnode_add_sort(nhgc->nhg_list, nh);
 }
 
@@ -629,7 +664,7 @@ static bool nexthop_group_parse_nexthop(struct nexthop *nhop,
 					const union sockunion *addr,
 					const char *intf, const char *name,
 					const char *labels, int *lbl_ret,
-					uint32_t weight)
+					uint32_t weight, int backup_idx)
 {
 	int ret = 0;
 	struct vrf *vrf;
@@ -688,6 +723,15 @@ static bool nexthop_group_parse_nexthop(struct nexthop *nhop,
 
 	nhop->weight = weight;
 
+	if (backup_idx != NHH_BACKUP_IDX_INVALID) {
+		/* Validate index value */
+		if (backup_idx > NEXTHOP_BACKUP_IDX_MAX)
+			return false;
+
+		SET_FLAG(nhop->flags, NEXTHOP_FLAG_HAS_BACKUP);
+		nhop->backup_idx = backup_idx;
+	}
+
 	return true;
 }
 
@@ -699,7 +743,7 @@ static bool nexthop_group_parse_nhh(struct nexthop *nhop,
 {
 	return (nexthop_group_parse_nexthop(nhop, nhh->addr, nhh->intf,
 					    nhh->nhvrf_name, nhh->labels, NULL,
-					    nhh->weight));
+					    nhh->weight, nhh->backup_idx));
 }
 
 DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
@@ -712,6 +756,7 @@ DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
 	   nexthop-vrf NAME$vrf_name \
 	   |label WORD \
            |weight (1-255) \
+           |backup-idx$bi_str (0-254)$idx \
 	}]",
       NO_STR
       "Specify one of the nexthops in this ECMP group\n"
@@ -724,16 +769,23 @@ DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
       "Specify label(s) for this nexthop\n"
       "One or more labels in the range (16-1048575) separated by '/'\n"
       "Weight to be used by the nexthop for purposes of ECMP\n"
-      "Weight value to be used\n")
+      "Weight value to be used\n"
+      "Backup nexthop index in another group\n"
+      "Nexthop index value\n")
 {
 	VTY_DECLVAR_CONTEXT(nexthop_group_cmd, nhgc);
 	struct nexthop nhop;
 	struct nexthop *nh;
 	int lbl_ret = 0;
 	bool legal;
+	int backup_idx = idx;
+	bool add_update = false;
+
+	if (bi_str == NULL)
+		backup_idx = NHH_BACKUP_IDX_INVALID;
 
 	legal = nexthop_group_parse_nexthop(&nhop, addr, intf, vrf_name, label,
-					    &lbl_ret, weight);
+					    &lbl_ret, weight, backup_idx);
 
 	if (nhop.type == NEXTHOP_TYPE_IPV6
 	    && IN6_IS_ADDR_LINKLOCAL(&nhop.gate.ipv6)) {
@@ -765,19 +817,30 @@ DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
 
 	nh = nexthop_exists(&nhgc->nhg, &nhop);
 
-	if (no) {
+	if (no || nh) {
+		/* Remove or replace cases */
+
+		/* Remove existing config */
 		nexthop_group_unsave_nhop(nhgc, vrf_name, addr, intf, label,
 					  weight);
 		if (nh) {
+			/* Remove nexthop object */
 			_nexthop_del(&nhgc->nhg, nh);
 
 			if (nhg_hooks.del_nexthop)
 				nhg_hooks.del_nexthop(nhgc, nh);
 
 			nexthop_free(nh);
+			nh = NULL;
 		}
-	} else if (!nh) {
-		/* must be adding new nexthop since !no and !nexthop_exists */
+	}
+
+	add_update = !no;
+
+	if (add_update) {
+		/* Add or replace cases */
+
+		/* If valid config, add nexthop object */
 		if (legal) {
 			nh = nexthop_new();
 
@@ -785,8 +848,9 @@ DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
 			_nexthop_add(&nhgc->nhg.nexthop, nh);
 		}
 
+		/* Save config always */
 		nexthop_group_save_nhop(nhgc, vrf_name, addr, intf, label,
-					weight);
+					weight, backup_idx);
 
 		if (legal && nhg_hooks.add_nexthop)
 			nhg_hooks.add_nexthop(nhgc, nh);
@@ -849,6 +913,9 @@ void nexthop_group_write_nexthop(struct vty *vty, struct nexthop *nh)
 	if (nh->weight)
 		vty_out(vty, " weight %u", nh->weight);
 
+	if (CHECK_FLAG(nh->flags, NEXTHOP_FLAG_HAS_BACKUP))
+		vty_out(vty, " backup-idx %d", nh->backup_idx);
+
 	vty_out(vty, "\n");
 }
 
@@ -874,6 +941,9 @@ static void nexthop_group_write_nexthop_internal(struct vty *vty,
 	if (nh->weight)
 		vty_out(vty, " weight %u", nh->weight);
 
+	if (nh->backup_idx != NHH_BACKUP_IDX_INVALID)
+		vty_out(vty, " backup-idx %d", nh->backup_idx);
+
 	vty_out(vty, "\n");
 }
 
@@ -887,6 +957,10 @@ static int nexthop_group_write(struct vty *vty)
 
 		vty_out(vty, "nexthop-group %s\n", nhgc->name);
 
+		if (nhgc->backup_list_name[0])
+			vty_out(vty, " backup-group %s\n",
+				nhgc->backup_list_name);
+
 		for (ALL_LIST_ELEMENTS_RO(nhgc->nhg_list, node, nh)) {
 			vty_out(vty, " ");
 			nexthop_group_write_nexthop_internal(vty, nh);
@@ -1067,6 +1141,8 @@ void nexthop_group_init(void (*new)(const char *name),
 	install_element(CONFIG_NODE, &no_nexthop_group_cmd);
 
 	install_default(NH_GROUP_NODE);
+	install_element(NH_GROUP_NODE, &nexthop_group_backup_cmd);
+	install_element(NH_GROUP_NODE, &no_nexthop_group_backup_cmd);
 	install_element(NH_GROUP_NODE, &ecmp_nexthops_cmd);
 
 	memset(&nhg_hooks, 0, sizeof(nhg_hooks));
diff --git a/lib/nexthop_group.h b/lib/nexthop_group.h
index f99a53f694..3a5a1299c1 100644
--- a/lib/nexthop_group.h
+++ b/lib/nexthop_group.h
@@ -57,6 +57,8 @@ void copy_nexthops(struct nexthop **tnh, const struct nexthop *nh,
 uint32_t nexthop_group_hash_no_recurse(const struct nexthop_group *nhg);
 uint32_t nexthop_group_hash(const struct nexthop_group *nhg);
 void nexthop_group_mark_duplicates(struct nexthop_group *nhg);
+
+/* Add a nexthop to a list, enforcing the canonical sort order. */
 void nexthop_group_add_sorted(struct nexthop_group *nhg,
 			      struct nexthop *nexthop);
 
@@ -79,11 +81,16 @@ void nexthop_group_add_sorted(struct nexthop_group *nhg,
 	(nhop) = nexthop_next(nhop)
 
 
+#define NHGC_NAME_SIZE 80
+
 struct nexthop_group_cmd {
 
 	RB_ENTRY(nexthop_group_cmd) nhgc_entry;
 
-	char name[80];
+	char name[NHGC_NAME_SIZE];
+
+	/* Name of group containing backup nexthops (if set) */
+	char backup_list_name[NHGC_NAME_SIZE];
 
 	struct nexthop_group nhg;
 
diff --git a/lib/northbound_grpc.cpp b/lib/northbound_grpc.cpp
index 089899368d..b195f1aeca 100644
--- a/lib/northbound_grpc.cpp
+++ b/lib/northbound_grpc.cpp
@@ -884,7 +884,14 @@ static int frr_grpc_finish(void)
 	return 0;
 }
 
-static int frr_grpc_module_late_init(struct thread_master *tm)
+/*
+ * This is done this way because module_init and module_late_init are both
+ * called during daemon pre-fork initialization. Because the GRPC library
+ * spawns threads internally, we need to delay initializing it until after
+ * fork. This is done by scheduling this init function as an event task, since
+ * the event loop doesn't run until after fork.
+ */
+static int frr_grpc_module_very_late_init(struct thread *thread)
 {
 	static unsigned long port = GRPC_DEFAULT_PORT;
 	const char *args = THIS_MODULE->load_args;
@@ -910,15 +917,19 @@ static int frr_grpc_module_late_init(struct thread_master *tm)
 	if (frr_grpc_init(&port) < 0)
 		goto error;
 
-	hook_register(frr_fini, frr_grpc_finish);
-
-	return 0;
-
 error:
 	flog_err(EC_LIB_GRPC_INIT, "failed to initialize the gRPC module");
 	return -1;
 }
 
+static int frr_grpc_module_late_init(struct thread_master *tm)
+{
+	thread_add_event(tm, frr_grpc_module_very_late_init, NULL, 0, NULL);
+	hook_register(frr_fini, frr_grpc_finish);
+
+	return 0;
+}
+
 static int frr_grpc_module_init(void)
 {
 	hook_register(frr_late_init, frr_grpc_module_late_init);
diff --git a/lib/plist.c b/lib/plist.c
index 40131aebed..b7a020c6f7 100644
--- a/lib/plist.c
+++ b/lib/plist.c
@@ -778,7 +778,7 @@ static void __attribute__((unused)) prefix_list_print(struct prefix_list *plist)
 
 			p = &pentry->prefix;
 
-			printf("  seq %" PRId64 " %s %s/%d", pentry->seq,
+			printf("  seq %lld %s %s/%d", (long long)pentry->seq,
 			       prefix_list_type_str(pentry),
 			       inet_ntop(p->family, p->u.val, buf, BUFSIZ),
 			       p->prefixlen);
diff --git a/lib/prefix.h b/lib/prefix.h
index b01f7d1fdc..f2952c38c3 100644
--- a/lib/prefix.h
+++ b/lib/prefix.h
@@ -531,7 +531,7 @@ static inline int is_host_route(struct prefix *p)
 	return 0;
 }
 
-static inline int is_default_host_route(struct prefix *p)
+static inline int is_default_host_route(const struct prefix *p)
 {
 	if (p->family == AF_INET) {
 		return (p->u.prefix4.s_addr == INADDR_ANY &&
@@ -544,6 +544,22 @@ static inline int is_default_host_route(struct prefix *p)
 	return 0;
 }
 
+#ifdef _FRR_ATTRIBUTE_PRINTFRR
+#pragma FRR printfrr_ext "%pI4"  (struct in_addr *)
+#pragma FRR printfrr_ext "%pI4"  (in_addr_t *)
+
+#pragma FRR printfrr_ext "%pI6"  (struct in6_addr *)
+
+#pragma FRR printfrr_ext "%pFX"  (struct prefix *)
+#pragma FRR printfrr_ext "%pFX"  (struct prefix_ipv4 *)
+#pragma FRR printfrr_ext "%pFX"  (struct prefix_ipv6 *)
+#pragma FRR printfrr_ext "%pFX"  (struct prefix_eth *)
+#pragma FRR printfrr_ext "%pFX"  (struct prefix_evpn *)
+#pragma FRR printfrr_ext "%pFX"  (struct prefix_fs *)
+
+#pragma FRR printfrr_ext "%pSG4" (struct prefix_sg *)
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/printfrr.h b/lib/printfrr.h
index f9584bcacc..7d9e288655 100644
--- a/lib/printfrr.h
+++ b/lib/printfrr.h
@@ -30,8 +30,7 @@ struct fbuf {
 	size_t len;
 };
 
-#define at(a, b) \
-	__attribute__((format(printf, a, b)))
+#define at(a, b) PRINTFRR(a, b)
 #define atn(a, b) \
 	at(a, b) __attribute__((nonnull(1) _RET_NONNULL))
 #define atm(a, b) \
@@ -73,8 +72,19 @@ char *vasnprintfrr(struct memtype *mt, char *out, size_t sz,
 char  *asnprintfrr(struct memtype *mt, char *out, size_t sz,
 		   const char *fmt, ...)     atn(4, 5);
 
+#define printfrr(fmt, ...)                                                     \
+	do {                                                                   \
+		char buf[256], *out;                                           \
+		out = asnprintfrr(MTYPE_TMP, buf, sizeof(buf), fmt,            \
+				  ##__VA_ARGS__);                              \
+		fputs(out, stdout);                                            \
+		if (out != buf)                                                \
+			XFREE(MTYPE_TMP, out);                                 \
+	} while (0)
+
 #undef at
 #undef atm
+#undef atn
 
 /* extension specs must start with a capital letter (this is a restriction
  * for both performance's and human understanding's sake.)
diff --git a/lib/routemap_cli.c b/lib/routemap_cli.c
index 5b03b5266f..41e8cacd81 100644
--- a/lib/routemap_cli.c
+++ b/lib/routemap_cli.c
@@ -148,6 +148,12 @@ void route_map_instance_show(struct vty *vty, struct lyd_node *dnode,
 		SKIP_RULE("ipv6 next-hop type");
 		SKIP_RULE("metric");
 		SKIP_RULE("tag");
+		/* Zebra specific match conditions. */
+		SKIP_RULE("ip address prefix-len");
+		SKIP_RULE("ipv6 address prefix-len");
+		SKIP_RULE("ip next-hop prefix-len");
+		SKIP_RULE("source-protocol");
+		SKIP_RULE("source-instance");
 
 		vty_out(vty, " match %s %s\n", rmr->cmd->str,
 			rmr->rule_str ? rmr->rule_str : "");
@@ -158,6 +164,8 @@ void route_map_instance_show(struct vty *vty, struct lyd_node *dnode,
 		/* Skip all sets implemented by northbound. */
 		SKIP_RULE("metric");
 		SKIP_RULE("tag");
+		/* Zebra specific set actions. */
+		SKIP_RULE("src");
 
 		vty_out(vty, " set %s %s\n", rmr->cmd->str,
 			rmr->rule_str ? rmr->rule_str : "");
@@ -666,8 +674,25 @@ void route_map_condition_show(struct vty *vty, struct lyd_node *dnode,
 		vty_out(vty, " match tag %s\n",
 			yang_dnode_get_string(dnode, "./tag"));
 		break;
-	case 100:
-		/* NOTHING: custom field, should be handled by daemon. */
+	case 100: /* ipv4-prefix-length */
+		vty_out(vty, " match ip address prefix-len %s\n",
+			yang_dnode_get_string(dnode,"./frr-zebra:ipv4-prefix-length"));
+		break;
+	case 101: /* ipv6-prefix-length */
+		vty_out(vty, " match ipv6 address prefix-len %s\n",
+			yang_dnode_get_string(dnode, "./frr-zebra:ipv6-prefix-length"));
+		break;
+	case 102: /* ipv4-next-hop-prefix-length */
+		vty_out(vty, " match ip next-hop prefix-len %s\n",
+			yang_dnode_get_string(dnode, "./frr-zebra:ipv4-prefix-length"));
+		break;
+	case 103: /* source-protocol */
+		vty_out(vty, " match source-protocol %s\n",
+			yang_dnode_get_string(dnode, "./frr-zebra:source-protocol"));
+		break;
+	case 104: /* source-instance */
+		vty_out(vty, " match source-instance %s\n",
+			yang_dnode_get_string(dnode, "./frr-zebra:source-instance"));
 		break;
 	}
 }
@@ -868,8 +893,13 @@ void route_map_action_show(struct vty *vty, struct lyd_node *dnode,
 		vty_out(vty, " set tag %s\n",
 			yang_dnode_get_string(dnode, "./tag"));
 		break;
-	case 100:
-		/* NOTHING: custom field, should be handled by daemon. */
+	case 100: /* source */
+		if (yang_dnode_exists(dnode, "./frr-zebra:source-v4"))
+			vty_out(vty, " set src %s\n",
+				yang_dnode_get_string(dnode, "./frr-zebra:source-v4"));
+		else
+			vty_out(vty, " set src %s\n",
+				yang_dnode_get_string(dnode, "./frr-zebra:source-v6"));
 		break;
 	}
 }
diff --git a/lib/skiplist.c b/lib/skiplist.c
index d955c6eb9e..fa25770efa 100644
--- a/lib/skiplist.c
+++ b/lib/skiplist.c
@@ -112,7 +112,7 @@ static int randomLevel(void)
 	return level;
 }
 
-static int default_cmp(void *key1, void *key2)
+static int default_cmp(const void *key1, const void *key2)
 {
 	if (key1 < key2)
 		return -1;
@@ -126,7 +126,8 @@ unsigned int skiplist_count(struct skiplist *l)
 	return l->count;
 }
 
-struct skiplist *skiplist_new(int flags, int (*cmp)(void *key1, void *key2),
+struct skiplist *skiplist_new(int flags,
+			      int (*cmp)(const void *key1, const void *key2),
 			      void (*del)(void *val))
 {
 	struct skiplist *new;
@@ -329,8 +330,8 @@ int skiplist_delete(register struct skiplist *l, register void *key,
  * Also set a cursor for use with skiplist_next_value.
  */
 int skiplist_first_value(register struct skiplist *l, /* in */
-			 register void *key,	  /* in */
-			 void **valuePointer,	 /* out */
+			 register const void *key,    /* in */
+			 void **valuePointer,	      /* out */
 			 void **cursor)		      /* out */
 {
 	register int k;
@@ -374,7 +375,7 @@ int skiplist_search(register struct skiplist *l, register void *key,
  * last element with the given key, -1 is returned.
  */
 int skiplist_next_value(register struct skiplist *l, /* in */
-			register void *key,	  /* in */
+			register const void *key,	  /* in */
 			void **valuePointer,	 /* in/out */
 			void **cursor)		     /* in/out */
 {
diff --git a/lib/skiplist.h b/lib/skiplist.h
index 2ab37331c9..a106a455d6 100644
--- a/lib/skiplist.h
+++ b/lib/skiplist.h
@@ -68,7 +68,7 @@ struct skiplist {
 	 * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
 	 * Used as definition of sorted for listnode_add_sort
 	 */
-	int (*cmp)(void *val1, void *val2);
+	int (*cmp)(const void *val1, const void *val2);
 
 	/* callback to free user-owned data when listnode is deleted. supplying
 	 * this callback is very much encouraged!
@@ -81,8 +81,9 @@ struct skiplist {
 extern struct skiplist *
 skiplist_new(/* encouraged: set list.del callback on new lists */
 	     int flags,
-	     int (*cmp)(void *key1, void *key2), /* NULL => default cmp */
-	     void (*del)(void *val));		 /* NULL => no auto val free */
+	     int (*cmp)(const void *key1,
+			const void *key2), /* NULL => default cmp */
+	     void (*del)(void *val));	   /* NULL => no auto val free */
 
 extern void skiplist_free(struct skiplist *);
 
@@ -96,12 +97,12 @@ extern int skiplist_search(register struct skiplist *l, register void *key,
 			   void **valuePointer);
 
 extern int skiplist_first_value(register struct skiplist *l, /* in */
-				register void *key,	  /* in */
-				void **valuePointer,	 /* in/out */
+				register const void *key,    /* in */
+				void **valuePointer,	     /* in/out */
 				void **cursor);		     /* out */
 
 extern int skiplist_next_value(register struct skiplist *l, /* in */
-			       register void *key,	  /* in */
+			       register const void *key,	  /* in */
 			       void **valuePointer,	 /* in/out */
 			       void **cursor);		    /* in/out */
 
diff --git a/lib/smux.h b/lib/smux.h
index 3f860db0dc..6896f02354 100644
--- a/lib/smux.h
+++ b/lib/smux.h
@@ -105,7 +105,7 @@ extern int smux_trap(struct variable *, size_t, const oid *, size_t,
 extern int oid_compare(const oid *, int, const oid *, int);
 extern void oid2in_addr(oid[], int, struct in_addr *);
 extern void *oid_copy(void *, const void *, size_t);
-extern void oid_copy_addr(oid[], struct in_addr *, int);
+extern void oid_copy_addr(oid[], const struct in_addr *, int);
 
 #ifdef __cplusplus
 }
diff --git a/lib/snmp.c b/lib/snmp.c
index f11d9dc8cf..736a3c62b8 100644
--- a/lib/snmp.c
+++ b/lib/snmp.c
@@ -64,10 +64,10 @@ void oid2in_addr(oid oid[], int len, struct in_addr *addr)
 		*pnt++ = oid[i];
 }
 
-void oid_copy_addr(oid oid[], struct in_addr *addr, int len)
+void oid_copy_addr(oid oid[], const struct in_addr *addr, int len)
 {
 	int i;
-	uint8_t *pnt;
+	const uint8_t *pnt;
 
 	if (len == 0)
 		return;
diff --git a/lib/spf_backoff.c b/lib/spf_backoff.c
index 41d4e2bb57..4e74714489 100644
--- a/lib/spf_backoff.c
+++ b/lib/spf_backoff.c
@@ -7,7 +7,7 @@
  * Copyright (C) 2017 Orange Labs http://www.orange.com/
  * Copyright (C) 2017 by Christian Franke, Open Source Routing / NetDEF Inc.
  *
- * This file is part of FreeRangeRouting (FRR)
+ * This file is part of FRRouting (FRR)
  *
  * FRR is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
diff --git a/lib/spf_backoff.h b/lib/spf_backoff.h
index 11b2701e3e..2617195d79 100644
--- a/lib/spf_backoff.h
+++ b/lib/spf_backoff.h
@@ -7,7 +7,7 @@
  * Copyright (C) 2017 Orange Labs http://www.orange.com/
  * Copyright (C) 2017 by Christian Franke, Open Source Routing / NetDEF Inc.
  *
- * This file is part of FreeRangeRouting (FRR)
+ * This file is part of FRRouting (FRR)
  *
  * FRR is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
diff --git a/lib/srcdest_table.c b/lib/srcdest_table.c
index ee87d73077..66b735919b 100644
--- a/lib/srcdest_table.c
+++ b/lib/srcdest_table.c
@@ -4,7 +4,7 @@
  * Copyright (C) 2017 by David Lamparter & Christian Franke,
  *                       Open Source Routing / NetDEF Inc.
  *
- * This file is part of FreeRangeRouting (FRR)
+ * This file is part of FRRouting (FRR)
  *
  * FRR is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
diff --git a/lib/srcdest_table.h b/lib/srcdest_table.h
index 90418944c7..7982260777 100644
--- a/lib/srcdest_table.h
+++ b/lib/srcdest_table.h
@@ -4,7 +4,7 @@
  * Copyright (C) 2017 by David Lamparter & Christian Franke,
  *                       Open Source Routing / NetDEF Inc.
  *
- * This file is part of FreeRangeRouting (FRR)
+ * This file is part of FRRouting (FRR)
  *
  * FRR is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
diff --git a/lib/stream.c b/lib/stream.c
index dd4d5bd96d..f046572f41 100644
--- a/lib/stream.c
+++ b/lib/stream.c
@@ -898,7 +898,7 @@ int stream_put_prefix(struct stream *s, const struct prefix *p)
 }
 
 /* Put NLRI with label */
-int stream_put_labeled_prefix(struct stream *s, struct prefix *p,
+int stream_put_labeled_prefix(struct stream *s, const struct prefix *p,
 			      mpls_label_t *label, int addpath_encode,
 			      uint32_t addpath_tx_id)
 {
diff --git a/lib/stream.h b/lib/stream.h
index 36c65afa3c..6fcf9a53cf 100644
--- a/lib/stream.h
+++ b/lib/stream.h
@@ -196,7 +196,7 @@ extern int stream_put_prefix_addpath(struct stream *s,
 				     int addpath_encode,
 				     uint32_t addpath_tx_id);
 extern int stream_put_prefix(struct stream *s, const struct prefix *p);
-extern int stream_put_labeled_prefix(struct stream *, struct prefix *,
+extern int stream_put_labeled_prefix(struct stream *, const struct prefix *,
 				     mpls_label_t *, int addpath_encode,
 				     uint32_t addpath_tx_id);
 extern void stream_get(void *, struct stream *, size_t);
@@ -354,9 +354,10 @@ extern void stream_fifo_free(struct stream_fifo *fifo);
  * bit), for 64-bit values (you need to cast them anyway), and neither for
  * encoding (because it's downcasted.)
  */
-static inline uint8_t *ptr_get_be32(uint8_t *ptr, uint32_t *out)
+static inline const uint8_t *ptr_get_be32(const uint8_t *ptr, uint32_t *out)
 {
 	uint32_t tmp;
+
 	memcpy(&tmp, ptr, sizeof(tmp));
 	*out = ntohl(tmp);
 	return ptr + 4;
diff --git a/lib/table.h b/lib/table.h
index 7743d51681..9cd9503376 100644
--- a/lib/table.h
+++ b/lib/table.h
@@ -331,6 +331,10 @@ static inline int route_table_iter_started(route_table_iter_t *iter)
 	return iter->state != RT_ITER_STATE_INIT;
 }
 
+#ifdef _FRR_ATTRIBUTE_PRINTFRR
+#pragma FRR printfrr_ext "%pRN"  (struct route_node *)
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/thread.c b/lib/thread.c
index 2217a60f0a..dbf668a699 100644
--- a/lib/thread.c
+++ b/lib/thread.c
@@ -114,11 +114,10 @@ static void vty_out_cpu_thread_history(struct vty *vty,
 				       struct cpu_thread_history *a)
 {
 	vty_out(vty, "%5zu %10zu.%03zu %9zu %8zu %9zu %8zu %9zu",
-		(size_t)a->total_active,
-		a->cpu.total / 1000, a->cpu.total % 1000,
-		(size_t)a->total_calls,
-		a->cpu.total / a->total_calls, a->cpu.max,
-		a->real.total / a->total_calls, a->real.max);
+		(size_t)a->total_active, a->cpu.total / 1000,
+		a->cpu.total % 1000, (size_t)a->total_calls,
+		(size_t)(a->cpu.total / a->total_calls), a->cpu.max,
+		(size_t)(a->real.total / a->total_calls), a->real.max);
 	vty_out(vty, " %c%c%c%c%c %s\n",
 		a->types & (1 << THREAD_READ) ? 'R' : ' ',
 		a->types & (1 << THREAD_WRITE) ? 'W' : ' ',
diff --git a/lib/vty.c b/lib/vty.c
index 4dd6ec1b35..8056236de9 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -231,8 +231,13 @@ int vty_out(struct vty *vty, const char *format, ...)
 				strlen(filtered));
 		break;
 	case VTY_SHELL:
-		fprintf(vty->of, "%s", filtered);
-		fflush(vty->of);
+		if (vty->of) {
+			fprintf(vty->of, "%s", filtered);
+			fflush(vty->of);
+		} else if (vty->of_saved) {
+			fprintf(vty->of_saved, "%s", filtered);
+			fflush(vty->of_saved);
+		}
 		break;
 	case VTY_SHELL_SERV:
 	case VTY_FILE:
diff --git a/lib/yang_wrappers.c b/lib/yang_wrappers.c
index a308b18b73..2b502d635b 100644
--- a/lib/yang_wrappers.c
+++ b/lib/yang_wrappers.c
@@ -22,6 +22,7 @@
 #include "log.h"
 #include "lib_errors.h"
 #include "northbound.h"
+#include "printfrr.h"
 
 static const char *yang_get_default_value(const char *xpath)
 {
@@ -443,7 +444,7 @@ struct yang_data *yang_data_new_int64(const char *xpath, int64_t value)
 {
 	char value_str[BUFSIZ];
 
-	snprintf(value_str, sizeof(value_str), "%" PRId64, value);
+	snprintfrr(value_str, sizeof(value_str), "%" PRId64, value);
 	return yang_data_new(xpath, value_str);
 }
 
@@ -651,7 +652,7 @@ struct yang_data *yang_data_new_uint64(const char *xpath, uint64_t value)
 {
 	char value_str[BUFSIZ];
 
-	snprintf(value_str, sizeof(value_str), "%" PRIu64, value);
+	snprintfrr(value_str, sizeof(value_str), "%" PRIu64, value);
 	return yang_data_new(xpath, value_str);
 }
 
diff --git a/lib/zclient.c b/lib/zclient.c
index eac6c7081d..d380267a70 100644
--- a/lib/zclient.c
+++ b/lib/zclient.c
@@ -52,7 +52,8 @@ static void zclient_event(enum event, struct zclient *);
 static void zebra_interface_if_set_value(struct stream *s,
 					 struct interface *ifp);
 
-struct zclient_options zclient_options_default = {.receive_notify = false};
+struct zclient_options zclient_options_default = {.receive_notify = false,
+						  .synchronous = false};
 
 struct sockaddr_storage zclient_addr;
 socklen_t zclient_addr_len;
@@ -76,6 +77,7 @@ struct zclient *zclient_new(struct thread_master *master,
 	zclient->master = master;
 
 	zclient->receive_notify = opt->receive_notify;
+	zclient->synchronous = opt->synchronous;
 
 	return zclient;
 }
@@ -374,11 +376,11 @@ static int zebra_message_send(struct zclient *zclient, int command,
 	return zclient_send_message(zclient);
 }
 
-static int zebra_hello_send(struct zclient *zclient)
+int zclient_send_hello(struct zclient *zclient)
 {
 	struct stream *s;
 
-	if (zclient->redist_default) {
+	if (zclient->redist_default || zclient->synchronous) {
 		s = zclient->obuf;
 		stream_reset(s);
 
@@ -390,6 +392,10 @@ static int zebra_hello_send(struct zclient *zclient)
 			stream_putc(s, 1);
 		else
 			stream_putc(s, 0);
+		if (zclient->synchronous)
+			stream_putc(s, 1);
+		else
+			stream_putc(s, 0);
 
 		stream_putw_at(s, 0, stream_get_endp(s));
 		return zclient_send_message(zclient);
@@ -629,7 +635,7 @@ int zclient_start(struct zclient *zclient)
 	/* Create read thread. */
 	zclient_event(ZCLIENT_READ, zclient);
 
-	zebra_hello_send(zclient);
+	zclient_send_hello(zclient);
 
 	zebra_message_send(zclient, ZEBRA_INTERFACE_ADD, VRF_DEFAULT);
 
@@ -690,8 +696,9 @@ static int zclient_connect(struct thread *t)
 	return zclient_start(zclient);
 }
 
-int zclient_send_rnh(struct zclient *zclient, int command, struct prefix *p,
-		     bool exact_match, vrf_id_t vrf_id)
+int zclient_send_rnh(struct zclient *zclient, int command,
+		     const struct prefix *p, bool exact_match,
+		     vrf_id_t vrf_id)
 {
 	struct stream *s;
 
@@ -897,6 +904,7 @@ int zapi_nexthop_encode(struct stream *s, const struct zapi_nexthop *api_nh,
 		}
 	}
 
+	/* If present, set 'weight' flag before encoding flags */
 	if (api_nh->weight)
 		SET_FLAG(nh_flags, ZAPI_NEXTHOP_FLAG_WEIGHT);
 
@@ -941,6 +949,10 @@ int zapi_nexthop_encode(struct stream *s, const struct zapi_nexthop *api_nh,
 		stream_put(s, &(api_nh->rmac),
 			   sizeof(struct ethaddr));
 
+	/* Index of backup nexthop */
+	if (CHECK_FLAG(nh_flags, ZAPI_NEXTHOP_FLAG_HAS_BACKUP))
+		stream_putc(s, api_nh->backup_idx);
+
 done:
 	return ret;
 }
@@ -1000,6 +1012,10 @@ int zapi_route_encode(uint8_t cmd, struct stream *s, struct zapi_route *api)
 			return -1;
 		}
 
+		/* We canonicalize the nexthops by sorting them; this allows
+		 * zebra to resolve the list of nexthops to a nexthop-group
+		 * more efficiently.
+		 */
 		zapi_nexthop_group_sort(api->nexthops, api->nexthop_num);
 
 		stream_putw(s, api->nexthop_num);
@@ -1026,6 +1042,50 @@ int zapi_route_encode(uint8_t cmd, struct stream *s, struct zapi_route *api)
 		}
 	}
 
+	/* Backup nexthops  */
+	if (CHECK_FLAG(api->message, ZAPI_MESSAGE_BACKUP_NEXTHOPS)) {
+		/* limit the number of nexthops if necessary */
+		if (api->backup_nexthop_num > MULTIPATH_NUM) {
+			char buf[PREFIX2STR_BUFFER];
+
+			prefix2str(&api->prefix, buf, sizeof(buf));
+			flog_err(
+				EC_LIB_ZAPI_ENCODE,
+				"%s: prefix %s: can't encode %u backup nexthops (maximum is %u)",
+				__func__, buf, api->backup_nexthop_num,
+				MULTIPATH_NUM);
+			return -1;
+		}
+
+		/* Note that we do not sort the list of backup nexthops -
+		 * this list is treated as an array and indexed by each
+		 * primary nexthop that is associated with a backup.
+		 */
+
+		stream_putw(s, api->backup_nexthop_num);
+
+		for (i = 0; i < api->backup_nexthop_num; i++) {
+			api_nh = &api->backup_nexthops[i];
+
+			/* MPLS labels for BGP-LU or Segment Routing */
+			if (api_nh->label_num > MPLS_MAX_LABELS) {
+				char buf[PREFIX2STR_BUFFER];
+
+				prefix2str(&api->prefix, buf, sizeof(buf));
+
+				flog_err(EC_LIB_ZAPI_ENCODE,
+					 "%s: prefix %s: backup: can't encode %u labels (maximum is %u)",
+					 __func__, buf,
+					 api_nh->label_num,
+					 MPLS_MAX_LABELS);
+				return -1;
+			}
+
+			if (zapi_nexthop_encode(s, api_nh, api->flags) != 0)
+				return -1;
+		}
+	}
+
 	/* Attributes. */
 	if (CHECK_FLAG(api->message, ZAPI_MESSAGE_DISTANCE))
 		stream_putc(s, api->distance);
@@ -1101,6 +1161,10 @@ static int zapi_nexthop_decode(struct stream *s, struct zapi_nexthop *api_nh,
 		STREAM_GET(&(api_nh->rmac), s,
 			   sizeof(struct ethaddr));
 
+	/* Backup nexthop index */
+	if (CHECK_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_HAS_BACKUP))
+		STREAM_GETC(s, api_nh->backup_idx);
+
 	/* Success */
 	ret = 0;
 
@@ -1207,6 +1271,24 @@ int zapi_route_decode(struct stream *s, struct zapi_route *api)
 		}
 	}
 
+	/* Backup nexthops. */
+	if (CHECK_FLAG(api->message, ZAPI_MESSAGE_BACKUP_NEXTHOPS)) {
+		STREAM_GETW(s, api->backup_nexthop_num);
+		if (api->backup_nexthop_num > MULTIPATH_NUM) {
+			flog_err(EC_LIB_ZAPI_ENCODE,
+				 "%s: invalid number of backup nexthops (%u)",
+				 __func__, api->backup_nexthop_num);
+			return -1;
+		}
+
+		for (i = 0; i < api->backup_nexthop_num; i++) {
+			api_nh = &api->backup_nexthops[i];
+
+			if (zapi_nexthop_decode(s, api_nh, api->flags) != 0)
+				return -1;
+		}
+	}
+
 	/* Attributes. */
 	if (CHECK_FLAG(api->message, ZAPI_MESSAGE_DISTANCE))
 		STREAM_GETC(s, api->distance);
@@ -1381,7 +1463,7 @@ stream_failure:
 	return false;
 }
 
-struct nexthop *nexthop_from_zapi_nexthop(struct zapi_nexthop *znh)
+struct nexthop *nexthop_from_zapi_nexthop(const struct zapi_nexthop *znh)
 {
 	struct nexthop *n = nexthop_new();
 
@@ -1398,6 +1480,11 @@ struct nexthop *nexthop_from_zapi_nexthop(struct zapi_nexthop *znh)
 				   znh->labels);
 	}
 
+	if (CHECK_FLAG(znh->flags, ZAPI_NEXTHOP_FLAG_HAS_BACKUP)) {
+		SET_FLAG(n->flags, NEXTHOP_FLAG_HAS_BACKUP);
+		n->backup_idx = znh->backup_idx;
+	}
+
 	return n;
 }
 
@@ -1413,10 +1500,16 @@ int zapi_nexthop_from_nexthop(struct zapi_nexthop *znh,
 
 	znh->type = nh->type;
 	znh->vrf_id = nh->vrf_id;
+	znh->weight = nh->weight;
 	znh->ifindex = nh->ifindex;
 	znh->gate = nh->gate;
 
 	if (nh->nh_label && (nh->nh_label->num_labels > 0)) {
+
+		/* Validate */
+		if (nh->nh_label->num_labels > MPLS_MAX_LABELS)
+			return -1;
+
 		for (i = 0; i < nh->nh_label->num_labels; i++)
 			znh->labels[i] = nh->nh_label->label[i];
 
@@ -1424,10 +1517,31 @@ int zapi_nexthop_from_nexthop(struct zapi_nexthop *znh,
 		SET_FLAG(znh->flags, ZAPI_NEXTHOP_FLAG_LABEL);
 	}
 
+	if (CHECK_FLAG(nh->flags, NEXTHOP_FLAG_HAS_BACKUP)) {
+		SET_FLAG(znh->flags, ZAPI_NEXTHOP_FLAG_HAS_BACKUP);
+		znh->backup_idx = nh->backup_idx;
+	}
+
 	return 0;
 }
 
 /*
+ * Wrapper that converts backup nexthop
+ */
+int zapi_backup_nexthop_from_nexthop(struct zapi_nexthop *znh,
+				     const struct nexthop *nh)
+{
+	int ret;
+
+	/* Ensure that zapi flags are correct: backups don't have backups */
+	ret = zapi_nexthop_from_nexthop(znh, nh);
+	if (ret == 0)
+		UNSET_FLAG(znh->flags, ZAPI_NEXTHOP_FLAG_HAS_BACKUP);
+
+	return ret;
+}
+
+/*
  * Decode the nexthop-tracking update message
  */
 bool zapi_nexthop_update_decode(struct stream *s, struct zapi_route *nhr)
diff --git a/lib/zclient.h b/lib/zclient.h
index e6f4c747e3..e747809f16 100644
--- a/lib/zclient.h
+++ b/lib/zclient.h
@@ -255,6 +255,9 @@ struct zclient {
 	/* Do we care about failure events for route install? */
 	bool receive_notify;
 
+	/* Is this a synchronous client? */
+	bool synchronous;
+
 	/* Socket to zebra daemon. */
 	int sock;
 
@@ -338,6 +341,9 @@ struct zclient {
 #define ZAPI_MESSAGE_TAG      0x08
 #define ZAPI_MESSAGE_MTU      0x10
 #define ZAPI_MESSAGE_SRCPFX   0x20
+/* Backup nexthops are present */
+#define ZAPI_MESSAGE_BACKUP_NEXTHOPS 0x40
+
 /*
  * This should only be used by a DAEMON that needs to communicate
  * the table being used is not in the VRF.  You must pass the
@@ -374,14 +380,21 @@ struct zapi_nexthop {
 	struct ethaddr rmac;
 
 	uint32_t weight;
+
+	/* Index of backup nexthop */
+	uint8_t backup_idx;
 };
 
 /*
- * ZAPI nexthop flags values
+ * ZAPI nexthop flags values - we're encoding a single octet
+ * initially, so ensure that the on-the-wire encoding continues
+ * to match the number of valid flags.
  */
+
 #define ZAPI_NEXTHOP_FLAG_ONLINK	0x01
 #define ZAPI_NEXTHOP_FLAG_LABEL		0x02
 #define ZAPI_NEXTHOP_FLAG_WEIGHT	0x04
+#define ZAPI_NEXTHOP_FLAG_HAS_BACKUP	0x08 /* Nexthop has a backup */
 
 /*
  * Some of these data structures do not map easily to
@@ -445,6 +458,10 @@ struct zapi_route {
 	uint16_t nexthop_num;
 	struct zapi_nexthop nexthops[MULTIPATH_NUM];
 
+	/* Support backup routes for IP FRR, TI-LFA, traffic engineering */
+	uint16_t backup_nexthop_num;
+	struct zapi_nexthop backup_nexthops[MULTIPATH_NUM];
+
 	uint8_t distance;
 
 	uint32_t metric;
@@ -569,6 +586,7 @@ enum zebra_neigh_state { ZEBRA_NEIGH_INACTIVE = 0, ZEBRA_NEIGH_ACTIVE = 1 };
 
 struct zclient_options {
 	bool receive_notify;
+	bool synchronous;
 };
 
 extern struct zclient_options zclient_options_default;
@@ -738,7 +756,7 @@ extern void zebra_read_pw_status_update(ZAPI_CALLBACK_ARGS, struct zapi_pw_statu
 
 extern int zclient_route_send(uint8_t, struct zclient *, struct zapi_route *);
 extern int zclient_send_rnh(struct zclient *zclient, int command,
-			    struct prefix *p, bool exact_match,
+			    const struct prefix *p, bool exact_match,
 			    vrf_id_t vrf_id);
 int zapi_nexthop_encode(struct stream *s, const struct zapi_nexthop *api_nh,
 			uint32_t api_flags);
@@ -765,9 +783,12 @@ bool zapi_iptable_notify_decode(struct stream *s,
 		uint32_t *unique,
 		enum zapi_iptable_notify_owner *note);
 
-extern struct nexthop *nexthop_from_zapi_nexthop(struct zapi_nexthop *znh);
+extern struct nexthop *
+nexthop_from_zapi_nexthop(const struct zapi_nexthop *znh);
 int zapi_nexthop_from_nexthop(struct zapi_nexthop *znh,
 			      const struct nexthop *nh);
+int zapi_backup_nexthop_from_nexthop(struct zapi_nexthop *znh,
+				     const struct nexthop *nh);
 extern bool zapi_nexthop_update_decode(struct stream *s,
 				       struct zapi_route *nhr);
 
@@ -796,4 +817,9 @@ extern void zclient_send_mlag_deregister(struct zclient *client);
 extern void zclient_send_mlag_data(struct zclient *client,
 				   struct stream *client_s);
 
+/* Send the hello message.
+ * Returns 0 for success or -1 on an I/O error.
+ */
+extern int zclient_send_hello(struct zclient *client);
+
 #endif /* _ZEBRA_ZCLIENT_H */