*: move CLI node names to cmd_node->name

[mirror_frr.git] / lib / nexthop_group.c

/*
 * Nexthop Group structure definition.
 * Copyright (C) 2018 Cumulus Networks, Inc.
 *                    Donald Sharp
 *
 * This program 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 Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include <zebra.h>

#include <vrf.h>
#include <sockunion.h>
#include <nexthop.h>
#include <nexthop_group.h>
#include <nexthop_group_private.h>
#include <vty.h>
#include <command.h>
#include <jhash.h>

#ifndef VTYSH_EXTRACT_PL
#include "lib/nexthop_group_clippy.c"
#endif

DEFINE_MTYPE_STATIC(LIB, NEXTHOP_GROUP, "Nexthop Group")

/*
 * Internal struct used to hold nhg config strings
 */
struct nexthop_hold {
	char *nhvrf_name;
	union sockunion *addr;
	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,
			    const struct nexthop *nhop);
	void (*del_nexthop)(const struct nexthop_group_cmd *nhg,
			    const struct nexthop *nhop);
	void (*delete)(const char *name);
};

static struct nexthop_group_hooks nhg_hooks;

static inline int
nexthop_group_cmd_compare(const struct nexthop_group_cmd *nhgc1,
			  const struct nexthop_group_cmd *nhgc2);
RB_GENERATE(nhgc_entry_head, nexthop_group_cmd, nhgc_entry,
	    nexthop_group_cmd_compare)

static struct nhgc_entry_head nhgc_entries;

static inline int
nexthop_group_cmd_compare(const struct nexthop_group_cmd *nhgc1,
			  const struct nexthop_group_cmd *nhgc2)
{
	return strcmp(nhgc1->name, nhgc2->name);
}

static struct nexthop *nexthop_group_tail(const struct nexthop_group *nhg)
{
	struct nexthop *nexthop = nhg->nexthop;

	while (nexthop && nexthop->next)
		nexthop = nexthop->next;

	return nexthop;
}

uint8_t nexthop_group_nexthop_num(const struct nexthop_group *nhg)
{
	struct nexthop *nhop;
	uint8_t num = 0;

	for (ALL_NEXTHOPS_PTR(nhg, nhop))
		num++;

	return num;
}

uint8_t nexthop_group_nexthop_num_no_recurse(const struct nexthop_group *nhg)
{
	struct nexthop *nhop;
	uint8_t num = 0;

	for (nhop = nhg->nexthop; nhop; nhop = nhop->next)
		num++;

	return num;
}

uint8_t nexthop_group_active_nexthop_num(const struct nexthop_group *nhg)
{
	struct nexthop *nhop;
	uint8_t num = 0;

	for (ALL_NEXTHOPS_PTR(nhg, nhop)) {
		if (CHECK_FLAG(nhop->flags, NEXTHOP_FLAG_ACTIVE))
			num++;
	}

	return num;
}

uint8_t
nexthop_group_active_nexthop_num_no_recurse(const struct nexthop_group *nhg)
{
	struct nexthop *nhop;
	uint8_t num = 0;

	for (nhop = nhg->nexthop; nhop; nhop = nhop->next) {
		if (CHECK_FLAG(nhop->flags, NEXTHOP_FLAG_ACTIVE))
			num++;
	}

	return num;
}

struct nexthop *nexthop_exists(const struct nexthop_group *nhg,
			       const struct nexthop *nh)
{
	struct nexthop *nexthop;

	for (nexthop = nhg->nexthop; nexthop; nexthop = nexthop->next) {
		if (nexthop_same(nh, nexthop))
			return nexthop;
	}

	return NULL;
}

/*
 * Helper that locates a nexthop in an nhg config list. Note that
 * this uses a specific matching / equality rule that's different from
 * the complete match performed by 'nexthop_same()'.
 */
static struct nexthop *nhg_nh_find(const struct nexthop_group *nhg,
				   const struct nexthop *nh)
{
	struct nexthop *nexthop;
	int ret;

	/* We compare: vrf, gateway, and interface */

	for (nexthop = nhg->nexthop; nexthop; nexthop = nexthop->next) {

		/* Compare vrf and type */
		if (nexthop->vrf_id != nh->vrf_id)
			continue;
		if (nexthop->type != nh->type)
			continue;

		/* Compare gateway */
		switch (nexthop->type) {
		case NEXTHOP_TYPE_IPV4:
		case NEXTHOP_TYPE_IPV6:
			ret = nexthop_g_addr_cmp(nexthop->type,
						 &nexthop->gate, &nh->gate);
			if (ret != 0)
				continue;
			break;
		case NEXTHOP_TYPE_IPV4_IFINDEX:
		case NEXTHOP_TYPE_IPV6_IFINDEX:
			ret = nexthop_g_addr_cmp(nexthop->type,
						 &nexthop->gate, &nh->gate);
			if (ret != 0)
				continue;
			/* Intentional Fall-Through */
		case NEXTHOP_TYPE_IFINDEX:
			if (nexthop->ifindex != nh->ifindex)
				continue;
			break;
		case NEXTHOP_TYPE_BLACKHOLE:
			if (nexthop->bh_type != nh->bh_type)
				continue;
			break;
		}

		return nexthop;
	}

	return NULL;
}

static bool
nexthop_group_equal_common(const struct nexthop_group *nhg1,
			   const struct nexthop_group *nhg2,
			   uint8_t (*nexthop_group_nexthop_num_func)(
				   const struct nexthop_group *nhg))
{
	if (nhg1 && !nhg2)
		return false;

	if (!nhg1 && nhg2)
		return false;

	if (nhg1 == nhg2)
		return true;

	if (nexthop_group_nexthop_num_func(nhg1)
	    != nexthop_group_nexthop_num_func(nhg2))
		return false;

	return true;
}

/* This assumes ordered */
bool nexthop_group_equal_no_recurse(const struct nexthop_group *nhg1,
				    const struct nexthop_group *nhg2)
{
	struct nexthop *nh1 = NULL;
	struct nexthop *nh2 = NULL;

	if (!nexthop_group_equal_common(nhg1, nhg2,
					&nexthop_group_nexthop_num_no_recurse))
		return false;

	for (nh1 = nhg1->nexthop, nh2 = nhg2->nexthop; nh1 || nh2;
	     nh1 = nh1->next, nh2 = nh2->next) {
		if (nh1 && !nh2)
			return false;
		if (!nh1 && nh2)
			return false;
		if (!nexthop_same(nh1, nh2))
			return false;
	}

	return true;
}

/* This assumes ordered */
bool nexthop_group_equal(const struct nexthop_group *nhg1,
			 const struct nexthop_group *nhg2)
{
	struct nexthop *nh1 = NULL;
	struct nexthop *nh2 = NULL;

	if (!nexthop_group_equal_common(nhg1, nhg2, &nexthop_group_nexthop_num))
		return false;

	for (nh1 = nhg1->nexthop, nh2 = nhg2->nexthop; nh1 || nh2;
	     nh1 = nexthop_next(nh1), nh2 = nexthop_next(nh2)) {
		if (nh1 && !nh2)
			return false;
		if (!nh1 && nh2)
			return false;
		if (!nexthop_same(nh1, nh2))
			return false;
	}

	return true;
}
struct nexthop_group *nexthop_group_new(void)
{
	return XCALLOC(MTYPE_NEXTHOP_GROUP, sizeof(struct nexthop_group));
}

void nexthop_group_copy(struct nexthop_group *to,
			const struct nexthop_group *from)
{
	/* Copy everything, including recursive info */
	copy_nexthops(&to->nexthop, from->nexthop, NULL);
}

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);

	XFREE(MTYPE_NEXTHOP_GROUP, *nhg);
}

/* Add nexthop to the end of a nexthop list.  */
void _nexthop_add(struct nexthop **target, struct nexthop *nexthop)
{
	struct nexthop *last;

	for (last = *target; last && last->next; last = last->next)
		;
	if (last)
		last->next = nexthop;
	else
		*target = nexthop;
	nexthop->prev = last;
}

/* Add nexthop to sorted list of nexthops */
static void _nexthop_add_sorted(struct nexthop **head,
				struct nexthop *nexthop)
{
	struct nexthop *position, *prev;

	assert(!nexthop->next);

	for (position = *head, prev = NULL; position;
	     prev = position, position = position->next) {
		if (nexthop_cmp(position, nexthop) > 0) {
			nexthop->next = position;
			nexthop->prev = prev;

			if (nexthop->prev)
				nexthop->prev->next = nexthop;
			else
				*head = nexthop;

			position->prev = nexthop;
			return;
		}
	}

	nexthop->prev = prev;
	if (prev)
		prev->next = nexthop;
	else
		*head = nexthop;
}

void nexthop_group_add_sorted(struct nexthop_group *nhg,
			      struct nexthop *nexthop)
{
	struct nexthop *tail;

	assert(!nexthop->next);

	/* Try to just append to the end first;
	 * trust the list is already sorted
	 */
	tail = nexthop_group_tail(nhg);

	if (tail && (nexthop_cmp(tail, nexthop) < 0)) {
		tail->next = nexthop;
		nexthop->prev = tail;

		return;
	}

	_nexthop_add_sorted(&nhg->nexthop, nexthop);
}

/* Delete nexthop from a nexthop list.  */
void _nexthop_del(struct nexthop_group *nhg, struct nexthop *nh)
{
	struct nexthop *nexthop;

	for (nexthop = nhg->nexthop; nexthop; nexthop = nexthop->next) {
		if (nexthop_same(nh, nexthop))
			break;
	}

	assert(nexthop);

	if (nexthop->prev)
		nexthop->prev->next = nexthop->next;
	else
		nhg->nexthop = nexthop->next;

	if (nexthop->next)
		nexthop->next->prev = nexthop->prev;

	nh->prev = NULL;
	nh->next = NULL;
}

/* Unlink a nexthop from the list it's on, unconditionally */
static void nexthop_unlink(struct nexthop_group *nhg, struct nexthop *nexthop)
{

	if (nexthop->prev)
		nexthop->prev->next = nexthop->next;
	else {
		assert(nhg->nexthop == nexthop);
		assert(nexthop->prev == NULL);
		nhg->nexthop = nexthop->next;
	}

	if (nexthop->next)
		nexthop->next->prev = nexthop->prev;

	nexthop->prev = NULL;
	nexthop->next = NULL;
}

/*
 * Copy a list of nexthops in 'nh' to an nhg, enforcing canonical sort order
 */
void nexthop_group_copy_nh_sorted(struct nexthop_group *nhg,
				  const struct nexthop *nh)
{
	struct nexthop *nexthop, *tail;
	const struct nexthop *nh1;

	/* We'll try to append to the end of the new list;
	 * if the original list in nh is already sorted, this eliminates
	 * lots of comparison operations.
	 */
	tail = nexthop_group_tail(nhg);

	for (nh1 = nh; nh1; nh1 = nh1->next) {
		nexthop = nexthop_dup(nh1, NULL);

		if (tail && (nexthop_cmp(tail, nexthop) < 0)) {
			tail->next = nexthop;
			nexthop->prev = tail;

			tail = nexthop;
			continue;
		}

		_nexthop_add_sorted(&nhg->nexthop, nexthop);

		if (tail == NULL)
			tail = nexthop;
	}
}

/* Copy a list of nexthops, no effort made to sort or order them. */
void copy_nexthops(struct nexthop **tnh, const struct nexthop *nh,
		   struct nexthop *rparent)
{
	struct nexthop *nexthop;
	const struct nexthop *nh1;

	for (nh1 = nh; nh1; nh1 = nh1->next) {
		nexthop = nexthop_dup(nh1, rparent);
		_nexthop_add(tnh, nexthop);
	}
}

uint32_t nexthop_group_hash_no_recurse(const struct nexthop_group *nhg)
{
	struct nexthop *nh;
	uint32_t key = 0;

	/*
	 * We are not interested in hashing over any recursively
	 * resolved nexthops
	 */
	for (nh = nhg->nexthop; nh; nh = nh->next)
		key = jhash_1word(nexthop_hash(nh), key);

	return key;
}

uint32_t nexthop_group_hash(const struct nexthop_group *nhg)
{
	struct nexthop *nh;
	uint32_t key = 0;

	for (ALL_NEXTHOPS_PTR(nhg, nh))
		key = jhash_1word(nexthop_hash(nh), key);

	return key;
}

void nexthop_group_mark_duplicates(struct nexthop_group *nhg)
{
	struct nexthop *nexthop, *prev;

	for (ALL_NEXTHOPS_PTR(nhg, nexthop)) {
		UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_DUPLICATE);
		for (ALL_NEXTHOPS_PTR(nhg, prev)) {
			if (prev == nexthop)
				break;
			if (nexthop_same_firsthop(nexthop, prev)) {
				SET_FLAG(nexthop->flags,
					 NEXTHOP_FLAG_DUPLICATE);
				break;
			}
		}
	}
}

static void nhgc_delete_nexthops(struct nexthop_group_cmd *nhgc)
{
	struct nexthop *nexthop;

	nexthop = nhgc->nhg.nexthop;
	while (nexthop) {
		struct nexthop *next = nexthop_next(nexthop);

		_nexthop_del(&nhgc->nhg, nexthop);
		if (nhg_hooks.del_nexthop)
			nhg_hooks.del_nexthop(nhgc, nexthop);

		nexthop_free(nexthop);

		nexthop = next;
	}
}

struct nexthop_group_cmd *nhgc_find(const char *name)
{
	struct nexthop_group_cmd find;

	strlcpy(find.name, name, sizeof(find.name));

	return RB_FIND(nhgc_entry_head, &nhgc_entries, &find);
}

static int nhgc_cmp_helper(const char *a, const char *b)
{
	if (!a && !b)
		return 0;

	if (a && !b)
		return -1;

	if (!a && b)
		return 1;

	return strcmp(a, b);
}

static int nhgc_addr_cmp_helper(const union sockunion *a, const union sockunion *b)
{
	if (!a && !b)
		return 0;

	if (a && !b)
		return -1;

	if (!a && b)
		return 1;

	return sockunion_cmp(a, b);
}

static int nhgl_cmp(struct nexthop_hold *nh1, struct nexthop_hold *nh2)
{
	int ret;

	ret = nhgc_addr_cmp_helper(nh1->addr, nh2->addr);
	if (ret)
		return ret;

	ret = nhgc_cmp_helper(nh1->intf, nh2->intf);
	if (ret)
		return ret;

	ret = nhgc_cmp_helper(nh1->nhvrf_name, nh2->nhvrf_name);
	if (ret)
		return ret;

	return nhgc_cmp_helper(nh1->labels, nh2->labels);
}

static void nhgl_delete(struct nexthop_hold *nh)
{
	XFREE(MTYPE_TMP, nh->intf);

	XFREE(MTYPE_TMP, nh->nhvrf_name);

	if (nh->addr)
		sockunion_free(nh->addr);

	XFREE(MTYPE_TMP, nh->labels);

	XFREE(MTYPE_TMP, nh);
}

static struct nexthop_group_cmd *nhgc_get(const char *name)
{
	struct nexthop_group_cmd *nhgc;

	nhgc = nhgc_find(name);
	if (!nhgc) {
		nhgc = XCALLOC(MTYPE_TMP, sizeof(*nhgc));
		strlcpy(nhgc->name, name, sizeof(nhgc->name));

		QOBJ_REG(nhgc, nexthop_group_cmd);
		RB_INSERT(nhgc_entry_head, &nhgc_entries, nhgc);

		nhgc->nhg_list = list_new();
		nhgc->nhg_list->cmp = (int (*)(void *, void *))nhgl_cmp;
		nhgc->nhg_list->del = (void (*)(void *))nhgl_delete;

		if (nhg_hooks.new)
			nhg_hooks.new(name);
	}

	return nhgc;
}

static void nhgc_delete(struct nexthop_group_cmd *nhgc)
{
	nhgc_delete_nexthops(nhgc);

	if (nhg_hooks.delete)
		nhg_hooks.delete(nhgc->name);

	RB_REMOVE(nhgc_entry_head, &nhgc_entries, nhgc);

	list_delete(&nhgc->nhg_list);

	XFREE(MTYPE_TMP, nhgc);
}

DEFINE_QOBJ_TYPE(nexthop_group_cmd)

DEFUN_NOSH(nexthop_group, nexthop_group_cmd, "nexthop-group NHGNAME",
	   "Enter into the nexthop-group submode\n"
	   "Specify the NAME of the nexthop-group\n")
{
	const char *nhg_name = argv[1]->arg;
	struct nexthop_group_cmd *nhgc = NULL;

	nhgc = nhgc_get(nhg_name);
	VTY_PUSH_CONTEXT(NH_GROUP_NODE, nhgc);

	return CMD_SUCCESS;
}

DEFUN_NOSH(no_nexthop_group, no_nexthop_group_cmd, "no nexthop-group NHGNAME",
	   NO_STR
	   "Delete the nexthop-group\n"
	   "Specify the NAME of the nexthop-group\n")
{
	const char *nhg_name = argv[2]->arg;
	struct nexthop_group_cmd *nhgc = NULL;

	nhgc = nhgc_find(nhg_name);
	if (nhgc)
		nhgc_delete(nhgc);

	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, int backup_idx)
{
	struct nexthop_hold *nh;

	nh = XCALLOC(MTYPE_TMP, sizeof(*nh));

	if (nhvrf_name)
		nh->nhvrf_name = XSTRDUP(MTYPE_TMP, nhvrf_name);
	if (intf)
		nh->intf = XSTRDUP(MTYPE_TMP, intf);
	if (addr)
		nh->addr = sockunion_dup(addr);
	if (labels)
		nh->labels = XSTRDUP(MTYPE_TMP, labels);

	nh->weight = weight;

	nh->backup_idx = backup_idx;

	listnode_add_sort(nhgc->nhg_list, nh);
}

/*
 * Remove config info about a nexthop from group 'nhgc'. Note that we
 * use only a subset of the available attributes here to determine
 * a 'match'.
 * Note that this doesn't change the list of nexthops, only the config
 * information.
 */
static void nexthop_group_unsave_nhop(struct nexthop_group_cmd *nhgc,
				      const char *nhvrf_name,
				      const union sockunion *addr,
				      const char *intf)
{
	struct nexthop_hold *nh;
	struct listnode *node;

	for (ALL_LIST_ELEMENTS_RO(nhgc->nhg_list, node, nh)) {
		if (nhgc_cmp_helper(nhvrf_name, nh->nhvrf_name) == 0
		    && nhgc_addr_cmp_helper(addr, nh->addr) == 0
		    && nhgc_cmp_helper(intf, nh->intf) == 0)
			break;
	}

	/*
	 * Something has gone seriously wrong, fail gracefully
	 */
	if (!nh)
		return;

	list_delete_node(nhgc->nhg_list, node);
	nhgl_delete(nh);
}

/*
 * Parse the config strings we support for a single nexthop. This gets used
 * in a couple of different ways, and we distinguish between transient
 * failures - such as a still-unprocessed interface - and fatal errors
 * from label-string parsing.
 */
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, int backup_idx)
{
	int ret = 0;
	struct vrf *vrf;

	memset(nhop, 0, sizeof(*nhop));

	if (name)
		vrf = vrf_lookup_by_name(name);
	else
		vrf = vrf_lookup_by_id(VRF_DEFAULT);

	if (!vrf)
		return false;

	nhop->vrf_id = vrf->vrf_id;

	if (intf) {
		nhop->ifindex = ifname2ifindex(intf, vrf->vrf_id);
		if (nhop->ifindex == IFINDEX_INTERNAL)
			return false;
	}

	if (addr) {
		if (addr->sa.sa_family == AF_INET) {
			nhop->gate.ipv4.s_addr = addr->sin.sin_addr.s_addr;
			if (intf)
				nhop->type = NEXTHOP_TYPE_IPV4_IFINDEX;
			else
				nhop->type = NEXTHOP_TYPE_IPV4;
		} else {
			nhop->gate.ipv6 = addr->sin6.sin6_addr;
			if (intf)
				nhop->type = NEXTHOP_TYPE_IPV6_IFINDEX;
			else
				nhop->type = NEXTHOP_TYPE_IPV6;
		}
	} else
		nhop->type = NEXTHOP_TYPE_IFINDEX;

	if (labels) {
		uint8_t num = 0;
		mpls_label_t larray[MPLS_MAX_LABELS];

		ret = mpls_str2label(labels, &num, larray);

		/* Return label parse result */
		if (lbl_ret)
			*lbl_ret = ret;

		if (ret < 0)
			return false;
		else if (num > 0)
			nexthop_add_labels(nhop, ZEBRA_LSP_NONE,
					   num, larray);
	}

	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;
}

/*
 * Wrapper to parse the strings in a 'nexthop_hold'
 */
static bool nexthop_group_parse_nhh(struct nexthop *nhop,
				    const struct nexthop_hold *nhh)
{
	return (nexthop_group_parse_nexthop(nhop, nhh->addr, nhh->intf,
					    nhh->nhvrf_name, nhh->labels, NULL,
					    nhh->weight, nhh->backup_idx));
}

DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
      "[no] nexthop\
        <\
	  <A.B.C.D|X:X::X:X>$addr [INTERFACE$intf]\
	  |INTERFACE$intf\
	>\
	[{ \
	   nexthop-vrf NAME$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"
      "v4 Address\n"
      "v6 Address\n"
      "Interface to use\n"
      "Interface to use\n"
      "If the nexthop is in a different vrf tell us\n"
      "The nexthop-vrf Name\n"
      "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"
      "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 yes = !no;

	if (bi_str == NULL)
		backup_idx = NHH_BACKUP_IDX_INVALID;

	legal = nexthop_group_parse_nexthop(&nhop, addr, intf, vrf_name, label,
					    &lbl_ret, weight, backup_idx);

	if (nhop.type == NEXTHOP_TYPE_IPV6
	    && IN6_IS_ADDR_LINKLOCAL(&nhop.gate.ipv6)) {
		vty_out(vty,
			"Specified a v6 LL with no interface, rejecting\n");
		return CMD_WARNING_CONFIG_FAILED;
	}

	/* Handle label-string errors */
	if (!legal && lbl_ret < 0) {
		switch (lbl_ret) {
		case -1:
			vty_out(vty, "%% Malformed label(s)\n");
			break;
		case -2:
			vty_out(vty,
				"%% Cannot use reserved label(s) (%d-%d)\n",
				MPLS_LABEL_RESERVED_MIN,
				MPLS_LABEL_RESERVED_MAX);
			break;
		case -3:
			vty_out(vty,
				"%% Too many labels. Enter %d or fewer\n",
				MPLS_MAX_LABELS);
			break;
		}
		return CMD_WARNING_CONFIG_FAILED;
	}

	/* Look for an existing nexthop in the config. Note that the test
	 * here tests only some attributes - it's not a complete comparison.
	 * Note that we've got two kinds of objects to manage: 'nexthop_hold'
	 * that represent config that may or may not be valid (yet), and
	 * actual nexthops that have been validated and parsed.
	 */
	nh = nhg_nh_find(&nhgc->nhg, &nhop);

	/* Always attempt to remove old config info. */
	nexthop_group_unsave_nhop(nhgc, vrf_name, addr, intf);

	/* Remove any existing nexthop, for delete and replace cases. */
	if (nh) {
		nexthop_unlink(&nhgc->nhg, nh);

		if (nhg_hooks.del_nexthop)
			nhg_hooks.del_nexthop(nhgc, nh);

		nexthop_free(nh);
	}
	if (yes) {
		/* Add/replace case: capture nexthop if valid, and capture
		 * config info always.
		 */
		if (legal) {
			nh = nexthop_new();

			memcpy(nh, &nhop, sizeof(nhop));
			_nexthop_add(&nhgc->nhg.nexthop, nh);
		}

		/* Save config always */
		nexthop_group_save_nhop(nhgc, vrf_name, addr, intf, label,
					weight, backup_idx);

		if (legal && nhg_hooks.add_nexthop)
			nhg_hooks.add_nexthop(nhgc, nh);
	}

	return CMD_SUCCESS;
}

static int nexthop_group_write(struct vty *vty);
static struct cmd_node nexthop_group_node = {
	.name = "nexthop-group",
	.node = NH_GROUP_NODE,
	.parent_node = CONFIG_NODE,
	.prompt = "%s(config-nh-group)# ",
	.config_write = nexthop_group_write,
};

void nexthop_group_write_nexthop(struct vty *vty, struct nexthop *nh)
{
	char buf[100];
	struct vrf *vrf;

	vty_out(vty, "nexthop ");

	switch (nh->type) {
	case NEXTHOP_TYPE_IFINDEX:
		vty_out(vty, "%s", ifindex2ifname(nh->ifindex, nh->vrf_id));
		break;
	case NEXTHOP_TYPE_IPV4:
		vty_out(vty, "%s", inet_ntoa(nh->gate.ipv4));
		break;
	case NEXTHOP_TYPE_IPV4_IFINDEX:
		vty_out(vty, "%s %s", inet_ntoa(nh->gate.ipv4),
			ifindex2ifname(nh->ifindex, nh->vrf_id));
		break;
	case NEXTHOP_TYPE_IPV6:
		vty_out(vty, "%s",
			inet_ntop(AF_INET6, &nh->gate.ipv6, buf, sizeof(buf)));
		break;
	case NEXTHOP_TYPE_IPV6_IFINDEX:
		vty_out(vty, "%s %s",
			inet_ntop(AF_INET6, &nh->gate.ipv6, buf, sizeof(buf)),
			ifindex2ifname(nh->ifindex, nh->vrf_id));
		break;
	case NEXTHOP_TYPE_BLACKHOLE:
		break;
	}

	if (nh->vrf_id != VRF_DEFAULT) {
		vrf = vrf_lookup_by_id(nh->vrf_id);
		vty_out(vty, " nexthop-vrf %s", vrf->name);
	}

	if (nh->nh_label && nh->nh_label->num_labels > 0) {
		char buf[200];

		mpls_label2str(nh->nh_label->num_labels,
			       nh->nh_label->label,
			       buf, sizeof(buf), 0);
		vty_out(vty, " label %s", buf);
	}

	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");
}

static void nexthop_group_write_nexthop_internal(struct vty *vty,
						 struct nexthop_hold *nh)
{
	char buf[100];

	vty_out(vty, "nexthop");

	if (nh->addr)
		vty_out(vty, " %s", sockunion2str(nh->addr, buf, sizeof(buf)));

	if (nh->intf)
		vty_out(vty, " %s", nh->intf);

	if (nh->nhvrf_name)
		vty_out(vty, " nexthop-vrf %s", nh->nhvrf_name);

	if (nh->labels)
		vty_out(vty, " label %s", nh->labels);

	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");
}

static int nexthop_group_write(struct vty *vty)
{
	struct nexthop_group_cmd *nhgc;
	struct nexthop_hold *nh;

	RB_FOREACH (nhgc, nhgc_entry_head, &nhgc_entries) {
		struct listnode *node;

		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);
		}

		vty_out(vty, "!\n");
	}

	return 1;
}

void nexthop_group_enable_vrf(struct vrf *vrf)
{
	struct nexthop_group_cmd *nhgc;
	struct nexthop_hold *nhh;

	RB_FOREACH (nhgc, nhgc_entry_head, &nhgc_entries) {
		struct listnode *node;

		for (ALL_LIST_ELEMENTS_RO(nhgc->nhg_list, node, nhh)) {
			struct nexthop nhop;
			struct nexthop *nh;

			if (!nexthop_group_parse_nhh(&nhop, nhh))
				continue;

			nh = nexthop_exists(&nhgc->nhg, &nhop);

			if (nh)
				continue;

			if (nhop.vrf_id != vrf->vrf_id)
				continue;

			nh = nexthop_new();

			memcpy(nh, &nhop, sizeof(nhop));
			_nexthop_add(&nhgc->nhg.nexthop, nh);

			if (nhg_hooks.add_nexthop)
				nhg_hooks.add_nexthop(nhgc, nh);
		}
	}
}

void nexthop_group_disable_vrf(struct vrf *vrf)
{
	struct nexthop_group_cmd *nhgc;
	struct nexthop_hold *nhh;

	RB_FOREACH (nhgc, nhgc_entry_head, &nhgc_entries) {
		struct listnode *node;

		for (ALL_LIST_ELEMENTS_RO(nhgc->nhg_list, node, nhh)) {
			struct nexthop nhop;
			struct nexthop *nh;

			if (!nexthop_group_parse_nhh(&nhop, nhh))
				continue;

			nh = nexthop_exists(&nhgc->nhg, &nhop);

			if (!nh)
				continue;

			if (nh->vrf_id != vrf->vrf_id)
				continue;

			_nexthop_del(&nhgc->nhg, nh);

			if (nhg_hooks.del_nexthop)
				nhg_hooks.del_nexthop(nhgc, nh);

			nexthop_free(nh);
		}
	}
}

void nexthop_group_interface_state_change(struct interface *ifp,
					  ifindex_t oldifindex)
{
	struct nexthop_group_cmd *nhgc;
	struct nexthop_hold *nhh;

	RB_FOREACH (nhgc, nhgc_entry_head, &nhgc_entries) {
		struct listnode *node;
		struct nexthop *nh;

		if (if_is_up(ifp)) {
			for (ALL_LIST_ELEMENTS_RO(nhgc->nhg_list, node, nhh)) {
				struct nexthop nhop;

				if (!nexthop_group_parse_nhh(&nhop, nhh))
					continue;

				switch (nhop.type) {
				case NEXTHOP_TYPE_IPV4:
				case NEXTHOP_TYPE_IPV6:
				case NEXTHOP_TYPE_BLACKHOLE:
					continue;
				case NEXTHOP_TYPE_IFINDEX:
				case NEXTHOP_TYPE_IPV4_IFINDEX:
				case NEXTHOP_TYPE_IPV6_IFINDEX:
					break;
				}
				nh = nexthop_exists(&nhgc->nhg, &nhop);

				if (nh)
					continue;

				if (ifp->ifindex != nhop.ifindex)
					continue;

				nh = nexthop_new();

				memcpy(nh, &nhop, sizeof(nhop));
				_nexthop_add(&nhgc->nhg.nexthop, nh);

				if (nhg_hooks.add_nexthop)
					nhg_hooks.add_nexthop(nhgc, nh);
			}
		} else {
			struct nexthop *next_nh;

			for (nh = nhgc->nhg.nexthop; nh; nh = next_nh) {
				next_nh = nh->next;
				switch (nh->type) {
				case NEXTHOP_TYPE_IPV4:
				case NEXTHOP_TYPE_IPV6:
				case NEXTHOP_TYPE_BLACKHOLE:
					continue;
				case NEXTHOP_TYPE_IFINDEX:
				case NEXTHOP_TYPE_IPV4_IFINDEX:
				case NEXTHOP_TYPE_IPV6_IFINDEX:
					break;
				}

				if (oldifindex != nh->ifindex)
					continue;

				_nexthop_del(&nhgc->nhg, nh);

				if (nhg_hooks.del_nexthop)
					nhg_hooks.del_nexthop(nhgc, nh);

				nexthop_free(nh);
			}
		}
	}
}

static void nhg_name_autocomplete(vector comps, struct cmd_token *token)
{
	struct nexthop_group_cmd *nhgc;

	RB_FOREACH (nhgc, nhgc_entry_head, &nhgc_entries) {
		vector_set(comps, XSTRDUP(MTYPE_COMPLETION, nhgc->name));
	}
}

static const struct cmd_variable_handler nhg_name_handlers[] = {
	{.tokenname = "NHGNAME", .completions = nhg_name_autocomplete},
	{.completions = NULL}};

void nexthop_group_init(void (*new)(const char *name),
			void (*add_nexthop)(const struct nexthop_group_cmd *nhg,
					    const struct nexthop *nhop),
			void (*del_nexthop)(const struct nexthop_group_cmd *nhg,
					    const struct nexthop *nhop),
			void (*delete)(const char *name))
{
	RB_INIT(nhgc_entry_head, &nhgc_entries);

	cmd_variable_handler_register(nhg_name_handlers);

	install_node(&nexthop_group_node);
	install_element(CONFIG_NODE, &nexthop_group_cmd);
	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));

	if (new)
		nhg_hooks.new = new;
	if (add_nexthop)
		nhg_hooks.add_nexthop = add_nexthop;
	if (del_nexthop)
		nhg_hooks.del_nexthop = del_nexthop;
	if (delete)
		nhg_hooks.delete = delete;
}