icmp,icmp6: select nexthop based on ident field

icmp(6)_local_send access the nexthop to select the proper gateway.
This can't work with the nexthop group. As we can't use the rss field,
use the "ident" field instead.

Add smoke test for loadbalance.

Signed-off-by: Christophe Fontaine <[email protected]>

Author: christophefontaine

modules/ip/datapath/icmp_local_send.c

@@ -10,6 +10,7 @@
 #include <gr_ip4_datapath.h>
 #include <gr_log.h>
 #include <gr_mbuf.h>
+#include <gr_vec.h>
 
 #include <rte_icmp.h>
 #include <rte_ip.h>
@@ -46,6 +47,13 @@ int icmp_local_send(
 	struct ctl_to_stack *msg;
 	int ret;
 
+	if (gw->type == GR_NH_T_GROUP) {
+		struct nexthop_info_group *g = (struct nexthop_info_group *)gw->info;
+		if (g->n_members == 0)
+			return errno_set(EHOSTUNREACH);
+		gw = g->members[ident % g->n_members].nh;
+	}
+
 	if ((msg = calloc(1, sizeof(struct ctl_to_stack))) == NULL)
 		return errno_set(ENOMEM);
 
@@ -105,6 +113,11 @@ static uint16_t icmp_local_send_process(
 		icmp->icmp_seq_nb = rte_cpu_to_be_16(msg->seq_num);
 		icmp->icmp_ident = rte_cpu_to_be_16(msg->ident);
 
+		// Fake RSS to spread the traffic
+		// for ECMP routes or active/active bonds.
+		mbuf->hash.rss = msg->ident;
+		mbuf->ol_flags |= RTE_MBUF_F_RX_RSS_HASH;
+
 		data = ip_local_mbuf_data(mbuf);
 		data->proto = IPPROTO_ICMP;
 		data->len = sizeof(*icmp) + sizeof(clock_t);

modules/ip6/datapath/icmp6_local_send.c

@@ -11,6 +11,7 @@
 #include <gr_ip6_datapath.h>
 #include <gr_log.h>
 #include <gr_mbuf.h>
+#include <gr_vec.h>
 
 #include <rte_ip6.h>
 
@@ -46,6 +47,13 @@ int icmp6_local_send(
 	const struct nexthop *local;
 	int ret;
 
+	if (gw->type == GR_NH_T_GROUP) {
+		struct nexthop_info_group *g = (struct nexthop_info_group *)gw->info;
+		if (g->n_members == 0)
+			return errno_set(EHOSTUNREACH);
+		gw = g->members[ident % g->n_members].nh;
+	}
+
 	if ((local = addr6_get_preferred(gw->iface_id, &nexthop_info_l3(gw)->ipv6)) == NULL)
 		return -errno;
 
@@ -94,6 +102,11 @@ static uint16_t icmp6_local_send_process(
 		icmp6_echo->ident = rte_cpu_to_be_16(msg->ident);
 		icmp6_echo->seqnum = rte_cpu_to_be_16(msg->seq_num);
 
+		// Fake RSS to spread the traffic
+		// for ECMP routes or active/active bonds.
+		mbuf->hash.rss = msg->ident;
+		mbuf->ol_flags |= RTE_MBUF_F_RX_RSS_HASH;
+
 		payload = PAYLOAD(icmp6_echo);
 		*payload = gr_clock_us();
 

smoke/ip_loadbalance_test.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2025 Christophe Fontaine
+
+. $(dirname $0)/_init.sh
+
+p0=${run_id}0
+p1=${run_id}1
+p2=${run_id}2
+
+grcli interface add port $p0 devargs net_tap0,iface=$p0 mac f0:0d:ac:dc:00:00
+grcli interface add port $p1 devargs net_tap1,iface=$p1 mac f0:0d:ac:dc:00:01
+grcli interface add port $p2 devargs net_tap2,iface=$p2 mac f0:0d:ac:dc:00:02
+
+grcli address add 172.16.0.1/24 iface $p0
+grcli address add 172.16.1.1/24 iface $p1
+grcli address add 172.16.2.1/24 iface $p2
+
+netns_add ${run_id}
+ip -n ${run_id} link set lo up
+ip -n ${run_id} addr add 192.200.0.2/24 dev lo
+
+for n in 0 1; do
+	p=$run_id$n
+	ip link set $p netns ${run_id}
+	ip -n ${run_id} link set $p address ba:d0:ca:ca:00:0$n
+	ip -n ${run_id} link set $p up
+	ip -n ${run_id} addr add 172.16.$n.2/24 dev $p
+done
+
+# Add ECMP route
+grcli nexthop add l3 iface $p0 address 172.16.0.2 id 100
+grcli nexthop add l3 iface $p1 address 172.16.1.2 id 101
+grcli nexthop add group id 10 members nh 100 nh 101
+grcli route add 192.200.0.0/24 via id 10
+
+# Locally generated ICMP requests
+grcli ping 192.200.0.2 count 1 ident 1
+grcli ping 192.200.0.2 count 1 ident 2
+
+# Externally generated ICMP requests
+ip -n ${run_id} nexthop add id 1601 via 172.16.0.1 dev $p0
+ip -n ${run_id} nexthop add id 1611 via 172.16.1.1 dev $p1
+ip -n ${run_id} nexthop add id 1620 group 1601/1611
+
+ip -n ${run_id} route add 172.16.2.0/24 nhid 1620
+
+netns_add $p2
+ip link set $p2 netns $p2
+ip -n $p2 link set $p2 address ba:d0:ca:ca:00:02
+ip -n $p2 link set $p2 up
+ip -n $p2 addr add 172.16.2.2/24 dev $p2
+ip -n $p2 route add default via 172.16.2.1
+ip netns exec $p2 ping 192.200.0.2 -c 3
+
+grcli nexthop del 10