Subject: [PATCH iproute2-next] ip: Add support for nexthop objects

From: [email-masked]
Date: Fri, 31 Aug 2018 17:49:54 -0700

From: David Ahern <[email-masked]>

Signed-off-by: David Ahern <[email-masked]>
---
 include/uapi/linux/nexthop.h   |  56 ++++
 include/uapi/linux/rtnetlink.h |   8 +
 ip/Makefile                    |   3 +-
 ip/ip.c                        |   3 +-
 ip/ip_common.h                 |   7 +-
 ip/ipmonitor.c                 |   6 +
 ip/ipnexthop.c                 | 652 +++++++++++++++++++++++++++++++++++++++++
 ip/iproute.c                   |  19 +-
 8 files changed, 747 insertions(+), 7 deletions(-)
 create mode 100644 include/uapi/linux/nexthop.h
 create mode 100644 ip/ipnexthop.c

diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
new file mode 100644
index 000000000000..335182e8229a
--- /dev/null
+++ b/include/uapi/linux/nexthop.h
@@ -0,0 +1,56 @@
+#ifndef __LINUX_NEXTHOP_H
+#define __LINUX_NEXTHOP_H
+
+#include <linux/types.h>
+
+struct nhmsg {
+	unsigned char	nh_family;
+	unsigned char	nh_scope;     /* one of RT_SCOPE */
+	unsigned char	nh_protocol;  /* Routing protocol that installed nh */
+	unsigned char	resvd;
+	unsigned int	nh_flags;     /* RTNH_F flags */
+};
+
+struct nexthop_grp {
+	__u32	id;
+	__u32	weight;
+};
+
+enum {
+	NEXTHOP_GRP_TYPE_MPATH,  /* default type if not specified */
+	__NEXTHOP_GRP_TYPE_MAX,
+};
+
+#define NEXTHOP_GRP_TYPE_MAX (__NEXTHOP_GRP_TYPE_MAX - 1)
+
+
+/* NHA_ID	32-bit id for nexthop. id must be greater than 0.
+ *		id == 0 means assign an unused id.
+ */
+enum {
+	NHA_UNSPEC,
+	NHA_ID,		/* u32 */
+	NHA_GROUP,	/* array of nexthop_grp */
+	NHA_GROUP_TYPE,	/* u16 one of NEXTHOP_GRP_TYPE;
+			 * default is NEXTHOP_GRP_TYPE_MPATH */
+
+	/* if NHA_GROUP attribute is added, no other attributes can be set */
+
+	NHA_BLACKHOLE,	/* flag; nexthop used to blackhole packets */
+	NHA_OIF,	/* u32 */
+	NHA_FLOW,	/* u32 */
+
+	NHA_TABLE_ID,	/* u32 - table id to validate gateway */
+	NHA_GATEWAY,	/* be32 (IPv4) or in6_addr (IPv6) gw address */
+
+	/* Dump control attributes */
+	NHA_GROUPS,	/* flag; only return nexthop groups in dump */
+	NHA_MASTER,	/* u32; only return nexthops with given master dev */
+
+	NHA_SADDR,	/* return only: IPv4 or IPv6 source address */
+
+	__NHA_MAX,
+};
+
+#define NHA_MAX	(__NHA_MAX - 1)
+#endif
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 8c1d600bfa33..158114245b6c 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -157,6 +157,13 @@ enum {
 	RTM_GETCHAIN,
 #define RTM_GETCHAIN RTM_GETCHAIN
 
+	RTM_NEWNEXTHOP = 104,
+#define RTM_NEWNEXTHOP RTM_NEWNEXTHOP
+	RTM_DELNEXTHOP,
+#define RTM_DELNEXTHOP RTM_DELNEXTHOP
+	RTM_GETNEXTHOP,
+#define RTM_GETNEXTHOP RTM_GETNEXTHOP
+
 	__RTM_MAX,
 #define RTM_MAX		(((__RTM_MAX + 3) & ~3) - 1)
 };
@@ -342,6 +349,7 @@ enum rtattr_type_t {
 	RTA_IP_PROTO,
 	RTA_SPORT,
 	RTA_DPORT,
+	RTA_NH_ID,
 	__RTA_MAX
 };
 
diff --git a/ip/Makefile b/ip/Makefile
index a88f93665ee6..7df818dbe23a 100644
--- a/ip/Makefile
+++ b/ip/Makefile
@@ -10,7 +10,8 @@ IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o ipnetns.o \
     link_iptnl.o link_gre6.o iplink_bond.o iplink_bond_slave.o iplink_hsr.o \
     iplink_bridge.o iplink_bridge_slave.o ipfou.o iplink_ipvlan.o \
     iplink_geneve.o iplink_vrf.o iproute_lwtunnel.o ipmacsec.o ipila.o \
-    ipvrf.o iplink_xstats.o ipseg6.o iplink_netdevsim.o iplink_rmnet.o
+    ipvrf.o iplink_xstats.o ipseg6.o iplink_netdevsim.o iplink_rmnet.o \
+    ipnexthop.o
 
 RTMONOBJ=rtmon.o
 
diff --git a/ip/ip.c b/ip/ip.c
index 58c643df8a36..963ef140c7c4 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -51,7 +51,7 @@ static void usage(void)
 "where  OBJECT := { link | address | addrlabel | route | rule | neigh | ntable |\n"
 "                   tunnel | tuntap | maddress | mroute | mrule | monitor | xfrm |\n"
 "                   netns | l2tp | fou | macsec | tcp_metrics | token | netconf | ila |\n"
-"                   vrf | sr }\n"
+"                   vrf | sr | nexthop }\n"
 "       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |\n"
 "                    -h[uman-readable] | -iec | -j[son] | -p[retty] |\n"
 "                    -f[amily] { inet | inet6 | ipx | dnet | mpls | bridge | link } |\n"
@@ -101,6 +101,7 @@ static const struct cmd {
 	{ "netconf",	do_ipnetconf },
 	{ "vrf",	do_ipvrf},
 	{ "sr",		do_seg6 },
+	{ "nexthop",	do_ipnh },
 	{ "help",	do_help },
 	{ 0 }
 };
diff --git a/ip/ip_common.h b/ip/ip_common.h
index 200be5e23dd1..2971c1586c4e 100644
--- a/ip/ip_common.h
+++ b/ip/ip_common.h
@@ -56,6 +56,8 @@ int print_rule(const struct sockaddr_nl *who,
 int print_netconf(const struct sockaddr_nl *who,
 		  struct rtnl_ctrl_data *ctrl,
 		  struct nlmsghdr *n, void *arg);
+int print_nexthop(const struct sockaddr_nl *who,
+		  struct nlmsghdr *n, void *arg);
 void netns_map_init(void);
 void netns_nsid_socket_init(void);
 int print_nsid(const struct sockaddr_nl *who,
@@ -90,6 +92,7 @@ int do_ipvrf(int argc, char **argv);
 void vrf_reset(void);
 int netns_identify_pid(const char *pidstr, char *name, int len);
 int do_seg6(int argc, char **argv);
+int do_ipnh(int argc, char **argv);
 
 int iplink_get(unsigned int flags, char *name, __u32 filt_mask);
 int iplink_ifla_xstats(int argc, char **argv);
@@ -165,5 +168,7 @@ int name_is_vrf(const char *name);
 #endif
 
 void print_num(FILE *fp, unsigned int width, uint64_t count);
-
+void print_rta_flow(FILE *fp, const struct rtattr *rta);
+void print_rt_flags(FILE *fp, unsigned int flags);
+void print_rta_if(FILE *fp, const struct rtattr *rta, const char *prefix);
 #endif /* _IP_COMMON_H_ */
diff --git a/ip/ipmonitor.c b/ip/ipmonitor.c
index a93b62cd6624..de129626683b 100644
--- a/ip/ipmonitor.c
+++ b/ip/ipmonitor.c
@@ -84,6 +84,12 @@ static int accept_msg(const struct sockaddr_nl *who,
 		}
 	}
 
+	case RTM_NEWNEXTHOP:
+	case RTM_DELNEXTHOP:
+		print_headers(fp, "[NEXTHOP]", ctrl);
+		print_nexthop(who, n, arg);
+		return 0;
+
 	case RTM_NEWLINK:
 	case RTM_DELLINK:
 		ll_remember_index(who, n, NULL);
diff --git a/ip/ipnexthop.c b/ip/ipnexthop.c
new file mode 100644
index 000000000000..9fa4b7292426
--- /dev/null
+++ b/ip/ipnexthop.c
@@ -0,0 +1,652 @@
+/*
+ * ip nexthop
+ *
+ * Copyright (C) 2017 Cumulus Networks
+ * Copyright (c) 2017 David Ahern <[email-masked]>
+ *
+ * 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <errno.h>
+#include <linux/nexthop.h>
+#include <libmnl/libmnl.h>
+#include <rt_names.h>
+
+#include "utils.h"
+#include "ip_common.h"
+
+static struct
+{
+	unsigned int flushed;
+	unsigned int groups;
+	char *flushb;
+	int flushp;
+	int flushe;
+} filter;
+
+enum {
+	IPNH_LIST,
+	IPNH_FLUSH,
+};
+
+#define RTM_NHA(h)  ((struct rtattr *)(((char *)(h)) + \
+			NLMSG_ALIGN(sizeof(struct nhmsg))))
+
+static void usage(void) __attribute__((noreturn));
+
+static void usage(void)
+{
+	fprintf(stderr, "Usage: ip nexthop { list | flush } SELECTOR\n");
+	fprintf(stderr, "       ip nexthop get [ id ID ]\n");
+	fprintf(stderr, "       ip nexthop { add | del | change | replace } NH\n");
+	fprintf(stderr, "SELECTOR := [ id ID ] [ dev DEV ] [ table TABLE ] [ vrf NAME ]\n");
+	fprintf(stderr, "NH := [ encap ENCAPTYPE ENCAPHDR ] [ via [ FAMILY ] ADDRESS ]\n");
+	fprintf(stderr, "      [ id ID ] [ dev STRING ] [ weight NUMBER ]\n");
+	fprintf(stderr, "      [ table TABLE ] [ vrf VRF ] NHFLAGS\n");
+	fprintf(stderr, "NHFLAGS := [ onlink | pervasive ]\n");
+	fprintf(stderr, "ENCAPTYPE := [ mpls | ip | ip6 ]\n");
+	fprintf(stderr, "ENCAPHDR := [ MPLSLABEL ]\n");
+	exit(-1);
+}
+
+static int delete_nexthop(__u32 id)
+{
+	struct {
+		struct nlmsghdr	n;
+		struct nhmsg	nhm;
+		char		buf[64];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct nhmsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = RTM_DELNEXTHOP,
+		.nhm.nh_family = AF_UNSPEC,
+	};
+
+	req.n.nlmsg_seq = ++rth.seq;
+
+	addattr32(&req.n, sizeof(req), NHA_ID, id);
+
+	if (rtnl_talk(&rth, &req.n, NULL) < 0)
+		return -1;
+
+	filter.flushed++;
+	return 0;
+}
+
+struct nh_entry {
+	__u32 id;
+	unsigned int group;
+	struct nh_entry *next;
+};
+
+struct nh_entry *first, *last;
+
+static int flush_nexthop(const struct sockaddr_nl *who,
+			 struct nlmsghdr *nlh, void *arg)
+{
+	struct nhmsg *nhm = NLMSG_DATA(nlh);
+	struct rtattr *tb[NHA_MAX+1];
+	struct nh_entry *nh;
+	__u32 id = 0;
+	int len;
+
+	len = nlh->nlmsg_len - NLMSG_SPACE(sizeof(*nhm));
+	if (len < 0) {
+		fprintf(stderr, "BUG: wrong nlmsg len %d\n", len);
+		return -1;
+	}
+
+	parse_rtattr(tb, NHA_MAX, RTM_NHA(nhm), len);
+	if (tb[NHA_ID])
+		id = rta_getattr_u32(tb[NHA_ID]);
+
+	if (!id)
+		return 0;
+
+	nh = malloc(sizeof(*nh));
+	if (!nh)
+		return -1;
+
+	nh->id = id;
+	nh->group = tb[NHA_GROUP] != NULL;
+	nh->next = NULL;
+	if (!first)
+		first = nh;
+	else
+		last->next = nh;
+
+	last = nh;
+	return 0;
+}
+
+static int ipnh_flush(void *req, __u32 len, unsigned int all)
+{
+	struct nh_entry *nh;
+
+	if (send(rth.fd, req, len, 0) < 0) {
+		perror("Cannot send dump request");
+		return -2;
+	}
+
+	if (rtnl_dump_filter(&rth, flush_nexthop, stdout) < 0) {
+		fprintf(stderr, "Dump terminated\n");
+		return -2;
+	}
+
+	/* if deleting all, then remove groups first */
+	if (all) {
+		nh = first;
+		while (nh) {
+			if (nh->group)
+				delete_nexthop(nh->id);
+			nh = nh->next;
+		}
+	}
+
+	nh = first;
+	while (nh) {
+		if (!all || !nh->group)
+			delete_nexthop(nh->id);
+		nh = nh->next;
+	}
+
+	if (!filter.flushed)
+		printf("Nothing to flush\n");
+	else
+		printf("Flushed %d nexthops\n", filter.flushed);
+
+	return 0;
+}
+
+static char *nh_group_type_to_str(__u16 group_type, char *buf, size_t len)
+{
+	static const char *typestr[NEXTHOP_GRP_TYPE_MAX + 1] = {
+		"multipath",   /* NEXTHOP_GRP_TYPE_MPATH */
+	};
+
+	if (group_type < ARRAY_SIZE(typestr))
+		snprintf(buf, len-1, "%s", typestr[group_type]);
+	else
+		snprintf(buf, len-1, "<%u>", group_type);
+
+	buf[len-1] = '\0';
+
+	return buf;
+}
+
+static void print_nh_group(FILE *fp, const struct rtattr *grps_attr,
+			   const struct rtattr *gtype)
+{
+	struct nexthop_grp *nhg = RTA_DATA(grps_attr);
+	int num = RTA_PAYLOAD(grps_attr) / sizeof(*nhg);
+	__u16 group_type = NEXTHOP_GRP_TYPE_MPATH;
+	int i;
+
+	SPRINT_BUF(b1);
+
+	if (!num || num * sizeof(*nhg) != RTA_PAYLOAD(grps_attr)) {
+		fprintf(fp, "<invalid nexthop group>");
+		return;
+	}
+
+	if (gtype)
+		group_type = rta_getattr_u16(gtype);
+
+	if (is_json_context()) {
+		open_json_array(PRINT_JSON, "group");
+		for (i = 0; i < num; ++i) {
+			open_json_object(NULL);
+			print_uint(PRINT_ANY, "id", "id %u ", nhg[i].id);
+			print_uint(PRINT_ANY, "weight", "weight %u ", nhg[i].weight);
+			close_json_object();
+		}
+		close_json_array(PRINT_JSON, NULL);
+		print_string(PRINT_ANY, "type", "type %s ",
+			     nh_group_type_to_str(group_type, b1, sizeof(b1)));
+	} else {
+		fprintf(fp, "group ");
+		for (i = 0; i < num; ++i) {
+			if (i)
+				fprintf(fp, "/");
+			fprintf(fp, "%u", nhg[i].id);
+			if (num > 1 && nhg[i].weight > 1)
+				fprintf(fp, ",%u", nhg[i].weight);
+		}
+	}
+}
+
+static void print_nh_gateway(FILE *fp, const struct nhmsg *nhm,
+			      const struct rtattr *rta)
+{
+	const char *gateway = format_host_rta(nhm->nh_family, rta);
+
+	if (is_json_context())
+		print_string(PRINT_JSON, "gateway", NULL, gateway);
+	else {
+		fprintf(fp, "via ");
+		print_color_string(PRINT_FP, ifa_family_color(nhm->nh_family),
+				  NULL, "%s ", gateway);
+	}
+}
+
+int print_nexthop(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
+{
+	struct nhmsg *nhm = NLMSG_DATA(n);
+	struct rtattr *tb[NHA_MAX+1];
+	FILE *fp = (FILE *)arg;
+	int len;
+
+	SPRINT_BUF(b1);
+
+	if (n->nlmsg_type != RTM_DELNEXTHOP &&
+	    n->nlmsg_type != RTM_NEWNEXTHOP) {
+		fprintf(stderr, "Not a nexthop: %08x %08x %08x\n",
+			n->nlmsg_len, n->nlmsg_type, n->nlmsg_flags);
+		return -1;
+	}
+
+	len = n->nlmsg_len - NLMSG_SPACE(sizeof(*nhm));
+	if (len < 0) {
+		close_json_object();
+		fprintf(stderr, "BUG: wrong nlmsg len %d\n", len);
+		return -1;
+	}
+
+	parse_rtattr(tb, NHA_MAX, RTM_NHA(nhm), len);
+
+	open_json_object(NULL);
+
+	if (n->nlmsg_type == RTM_DELROUTE)
+		print_bool(PRINT_ANY, "deleted", "Deleted ", true);
+
+	if (tb[NHA_ID])
+		print_uint(PRINT_ANY, "id", "id %u ",
+			   rta_getattr_u32(tb[NHA_ID]));
+
+	if (tb[NHA_GROUP])
+		print_nh_group(fp, tb[NHA_GROUP], tb[NHA_GROUP_TYPE]);
+
+	if (tb[NHA_GATEWAY])
+		print_nh_gateway(fp, nhm, tb[NHA_GATEWAY]);
+
+	if (tb[NHA_SADDR]) {
+		const char *psrc;
+
+		psrc = rt_addr_n2a_rta(nhm->nh_family, tb[NHA_SADDR]);
+		if (is_json_context())
+			print_string(PRINT_JSON, "src", NULL, psrc);
+		else {
+			fprintf(fp, "src ");
+			print_color_string(PRINT_FP,
+					   ifa_family_color(nhm->nh_family),
+					   NULL, "%s ", psrc);
+		}
+	}
+
+	if (tb[NHA_OIF])
+		print_rta_if(fp, tb[NHA_OIF], "dev");
+
+	if (tb[NHA_BLACKHOLE])
+		print_null(PRINT_ANY, "blackhole", "blackhole", NULL);
+
+	if (nhm->nh_protocol != RTPROT_UNSPEC || show_details > 0) {
+		print_string(PRINT_ANY, "protocol", "proto %s ",
+			     rtnl_rtprot_n2a(nhm->nh_protocol, b1, sizeof(b1)));
+	}
+
+	if (nhm->nh_scope != RT_SCOPE_UNIVERSE || show_details > 0) {
+		print_string(PRINT_ANY, "scope", "scope %s ",
+			     rtnl_rtscope_n2a(nhm->nh_scope, b1, sizeof(b1)));
+	}
+
+	if (tb[NHA_OIF])
+		print_rt_flags(fp, nhm->nh_flags);
+
+	if (tb[NHA_FLOW])
+		print_rta_flow(fp, tb[NHA_FLOW]);
+
+	print_string(PRINT_FP, NULL, "%s", "\n");
+	close_json_object();
+	fflush(fp);
+
+	return 0;
+}
+
+static int add_nh_group_attr(struct nlmsghdr *n, int maxlen, char *argv)
+{
+	struct nexthop_grp *grps;
+	int count = 0, i;
+	char *sep, *wsep;
+
+	if (*argv != '\0')
+		count = 1;
+
+	/* separator is '/' */
+	sep = strchr(argv, '/');
+	while (sep) {
+		count++;
+		sep = strchr(sep + 1, '/');
+	}
+
+	if (count == 0)
+		return -1;
+
+	grps = calloc(count, sizeof(*grps));
+	if (!grps)
+		return -1;
+
+	for (i = 0; i < count; ++i) {
+		sep = strchr(argv, '/');
+		if (sep)
+			*sep = '\0';
+
+		wsep = strchr(argv, ',');
+		if (wsep)
+			*wsep = '\0';
+
+		if (get_unsigned(&grps[i].id, argv, 0))
+			return -1;
+		if (wsep) {
+			wsep++;
+			if (get_unsigned(&grps[i].weight, wsep, 0))
+				return -1;
+		}
+
+		if (!sep)
+			break;
+
+		argv = sep + 1;
+	}
+
+	return addattr_l(n, maxlen, NHA_GROUP, grps, count * sizeof(*grps));
+}
+
+static int ipnh_modify(int cmd, unsigned int flags, int argc, char **argv)
+{
+	struct {
+		struct nlmsghdr	n;
+		struct nhmsg	nhm;
+		char		buf[1024];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct nhmsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST | flags,
+		.n.nlmsg_type = cmd,
+		.nhm.nh_family = AF_UNSPEC,
+	};
+	__u32 nh_flags = 0;
+	__u16 gtype = NEXTHOP_GRP_TYPE_MAX + 1;
+
+	while (argc > 0) {
+		if (!strcmp(*argv, "id")) {
+			__u32 id;
+
+			NEXT_ARG();
+			if (get_unsigned(&id, *argv, 0))
+				invarg("invalid id value", *argv);
+			addattr32(&req.n, sizeof(req), NHA_ID, id);
+		} else if (!strcmp(*argv, "dev")) {
+			int ifindex;
+
+			NEXT_ARG();
+			ifindex = ll_name_to_index(*argv);
+			if (!ifindex)
+				invarg("Device does not exist\n", *argv);
+			addattr32(&req.n, sizeof(req), NHA_OIF, ifindex);
+		} else if (strcmp(*argv, "via") == 0) {
+			inet_prefix addr;
+			int family;
+
+			NEXT_ARG();
+			family = read_family(*argv);
+			if (family == AF_UNSPEC)
+				family = req.nhm.nh_family;
+			else
+				NEXT_ARG();
+			get_addr(&addr, *argv, family);
+			if (req.nhm.nh_family == AF_UNSPEC)
+				req.nhm.nh_family = addr.family;
+			else if (req.nhm.nh_family != addr.family)
+				invarg("address family mismatch\n", *argv);
+			addattr_l(&req.n, sizeof(req), NHA_GATEWAY,
+				  &addr.data, addr.bytelen);
+		} else if (!strcmp(*argv, "blackhole")) {
+			addattr_l(&req.n, sizeof(req), NHA_BLACKHOLE, NULL, 0);
+		} else if (!strcmp(*argv, "onlink")) {
+			nh_flags |= RTNH_F_ONLINK;
+		} else if (!strcmp(*argv, "realms")) {
+			__u32 realm;
+
+			NEXT_ARG();
+			if (get_rt_realms_or_raw(&realm, *argv))
+				invarg("\"realm\" value is invalid\n", *argv);
+			addattr32(&req.n, sizeof(req), NHA_FLOW, realm);
+		} else if (!strcmp(*argv, "group")) {
+			NEXT_ARG();
+
+			if (add_nh_group_attr(&req.n, sizeof(req), *argv))
+				invarg("\"group\" value is invalid\n", *argv);
+		} else if (!strcmp(*argv, "multipath") ||
+			   !strcmp(*argv, "mpath")) {
+			gtype = NEXTHOP_GRP_TYPE_MPATH;
+		} else if (!strcmp(*argv, "table")) {
+			__u32 tb_id;
+
+			NEXT_ARG();
+			if (get_unsigned(&tb_id, *argv, 0))
+				invarg("invalid table value", *argv);
+			addattr32(&req.n, sizeof(req), NHA_TABLE_ID, tb_id);
+		} else if (strcmp(*argv, "vrf") == 0) {
+			__u32 tb_id;
+
+			NEXT_ARG();
+			tb_id = ipvrf_get_table(*argv);
+			if (tb_id == 0)
+				invarg("Invalid VRF", *argv);
+			addattr32(&req.n, sizeof(req), NHA_TABLE_ID, tb_id);
+		} else if (strcmp(*argv, "help") == 0) {
+			usage();
+		} else {
+			invarg("", *argv);
+		}
+		argc--; argv++;
+	}
+
+	if (gtype <= NEXTHOP_GRP_TYPE_MAX)
+		addattr16(&req.n, sizeof(req), NHA_GROUP_TYPE, gtype);
+
+	req.nhm.nh_flags = nh_flags;
+
+	if (rtnl_talk(&rth, &req.n, NULL) < 0)
+		return -2;
+
+	return 0;
+}
+
+static int ipnh_get_id(__u32 id)
+{
+	struct {
+		struct nlmsghdr	n;
+		struct nhmsg	nhm;
+		char		buf[1024];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct nhmsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type  = RTM_GETNEXTHOP,
+		.nhm.nh_family = preferred_family,
+	};
+	struct nlmsghdr *answer;
+
+	addattr32(&req.n, sizeof(req), NHA_ID, id);
+
+	if (rtnl_talk(&rth, &req.n, &answer) < 0)
+		return -2;
+
+	new_json_obj(json);
+
+	if (print_nexthop(NULL, answer, (void *)stdout) < 0) {
+		free(answer);
+		return -1;
+	}
+
+	delete_json_obj();
+	fflush(stdout);
+
+	free(answer);
+
+	return 0;
+}
+
+static int ipnh_list_flush(int argc, char **argv, int action)
+{
+	struct {
+		struct nlmsghdr	n;
+		struct nhmsg	nhm;
+		char		buf[256];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct nhmsg)),
+		.n.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.n.nlmsg_type  = RTM_GETNEXTHOP,
+		.n.nlmsg_seq = ++rth.seq,
+		.nhm.nh_family = preferred_family,
+	};
+	unsigned int master = 0;
+	unsigned int all = (argc == 0);
+
+	rth.dump = req.n.nlmsg_seq;
+
+	while (argc > 0) {
+		if (!matches(*argv, "dev")) {
+			unsigned int ifindex;
+
+			NEXT_ARG();
+			ifindex = ll_name_to_index(*argv);
+			if (!ifindex)
+				invarg("Device does not exist\n", *argv);
+			addattr32(&req.n, sizeof(req), NHA_OIF, ifindex);
+		} else if (!matches(*argv, "groups")) {
+			addattr_l(&req.n, sizeof(req), NHA_GROUPS, NULL, 0);
+		} else if (!matches(*argv, "master")) {
+			NEXT_ARG();
+			master = ll_name_to_index(*argv);
+			if (!master)
+				invarg("Device does not exist\n", *argv);
+		} else if (matches(*argv, "vrf") == 0) {
+			NEXT_ARG();
+			master = ll_name_to_index(*argv);
+			if (!master)
+				invarg("VRF does not exist\n", *argv);
+			if (!name_is_vrf(*argv))
+				invarg("Invalid VRF\n", *argv);
+		} else if (!strcmp(*argv, "id")) {
+			__u32 id;
+
+			NEXT_ARG();
+			if (get_unsigned(&id, *argv, 0))
+				invarg("invalid id value", *argv);
+			return ipnh_get_id(id);
+		} else if (matches(*argv, "help") == 0) {
+			usage();
+		} else {
+			invarg("", *argv);
+		}
+		argc--; argv++;
+	}
+
+	if (master)
+		addattr32(&req.n, sizeof(req), NHA_MASTER, master);
+
+	if (action == IPNH_FLUSH)
+		return ipnh_flush(&req, req.n.nlmsg_len, all);
+
+	if (send(rth.fd, &req, req.n.nlmsg_len, 0) < 0) {
+		perror("Cannot send dump request");
+		return -2;
+	}
+
+	new_json_obj(json);
+
+	if (rtnl_dump_filter(&rth, print_nexthop, stdout) < 0) {
+		fprintf(stderr, "Dump terminated\n");
+		return -2;
+	}
+
+	delete_json_obj();
+	fflush(stdout);
+
+	return 0;
+}
+
+static int ipnh_get(int argc, char **argv)
+{
+	__u32 id = 0;
+
+	while (argc > 0) {
+		if (!strcmp(*argv, "id")) {
+			NEXT_ARG();
+			if (get_unsigned(&id, *argv, 0))
+				invarg("invalid id value", *argv);
+		}
+		if (matches(*argv, "help") == 0)
+			usage();
+
+		argc--; argv++;
+	}
+
+	if (!id) {
+		usage();
+		return -1;
+	}
+
+	return ipnh_get_id(id);
+}
+
+int do_ipnh(int argc, char **argv)
+{
+	if (argc < 1)
+		return ipnh_list_flush(0, NULL, IPNH_LIST);
+
+	if (!matches(*argv, "add"))
+		return ipnh_modify(RTM_NEWNEXTHOP, NLM_F_CREATE|NLM_F_EXCL,
+				   argc-1, argv+1);
+	if (!matches(*argv, "change") || !strcmp(*argv, "chg"))
+		return ipnh_modify(RTM_NEWNEXTHOP, NLM_F_REPLACE,
+				   argc-1, argv+1);
+	if (!matches(*argv, "replace"))
+		return ipnh_modify(RTM_NEWNEXTHOP, NLM_F_CREATE|NLM_F_REPLACE,
+				   argc-1, argv+1);
+	if (!matches(*argv, "delete"))
+		return ipnh_modify(RTM_DELNEXTHOP, 0, argc-1, argv+1);
+
+	if (!matches(*argv, "list") ||
+	    !matches(*argv, "show") ||
+	    !matches(*argv, "lst"))
+		return ipnh_list_flush(argc-1, argv+1, IPNH_LIST);
+
+	if (!matches(*argv, "get"))
+		return ipnh_get(argc-1, argv+1);
+
+	if (!matches(*argv, "flush"))
+		return ipnh_list_flush(argc-1, argv+1, IPNH_FLUSH);
+
+	if (!matches(*argv, "help"))
+		usage();
+
+	fprintf(stderr,
+		"Command \"%s\" is unknown, try \"ip nexthop help\".\n", *argv);
+	exit(-1);
+}
diff --git a/ip/iproute.c b/ip/iproute.c
index 30833414a3f7..0af72c2eccca 100644
--- a/ip/iproute.c
+++ b/ip/iproute.c
@@ -349,7 +349,7 @@ static void print_rtax_features(FILE *fp, unsigned int features)
 			    "features", "0x%x ", of);
 }
 
-static void print_rt_flags(FILE *fp, unsigned int flags)
+void print_rt_flags(FILE *fp, unsigned int flags)
 {
 	open_json_array(PRINT_JSON,
 			is_json_context() ?  "flags" : "");
@@ -394,8 +394,8 @@ static void print_rt_pref(FILE *fp, unsigned int pref)
 	}
 }
 
-static void print_rta_if(FILE *fp, const struct rtattr *rta,
-			const char *prefix)
+void print_rta_if(FILE *fp, const struct rtattr *rta,
+		  const char *prefix)
 {
 	const char *ifname = ll_index_to_name(rta_getattr_u32(rta));
 
@@ -492,7 +492,7 @@ static void print_rta_cacheinfo(FILE *fp, const struct rta_cacheinfo *ci)
 	}
 }
 
-static void print_rta_flow(FILE *fp, const struct rtattr *rta)
+void print_rta_flow(FILE *fp, const struct rtattr *rta)
 {
 	__u32 to = rta_getattr_u32(rta);
 	__u32 from = to >> 16;
@@ -823,6 +823,10 @@ int print_route(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
 			     rtnl_dsfield_n2a(r->rtm_tos, b1, sizeof(b1)));
 	}
 
+	if (tb[RTA_NH_ID])
+		print_uint(PRINT_ANY, "nhid", "nhid %u ",
+			   rta_getattr_u32(tb[RTA_NH_ID]));
+
 	if (tb[RTA_GATEWAY] && filter.rvia.bitlen != host_len)
 		print_rta_gateway(fp, r, tb[RTA_GATEWAY]);
 
@@ -1351,6 +1355,13 @@ static int iproute_modify(int cmd, unsigned int flags, int argc, char **argv)
 		} else if (strcmp(*argv, "nexthop") == 0) {
 			nhs_ok = 1;
 			break;
+		} else if (!strcmp(*argv, "nhid")) {
+			__u32 id;
+
+			NEXT_ARG();
+			if (get_u32(&id, *argv, 0))
+				invarg("\"id\" value is invalid\n", *argv);
+			addattr32(&req.n, sizeof(req), RTA_NH_ID, id);
 		} else if (matches(*argv, "protocol") == 0) {
 			__u32 prot;
 
-- 
2.11.0