[ovs-dev,ovn,3/3] northd: introduce icmp6_error logical flows in router pipeline

diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml
index a7639f33a..97985a757 100644
--- a/northd/ovn-northd.8.xml
+++ b/northd/ovn-northd.8.xml
@@ -2856,11 +2856,11 @@  REGBIT_PKT_LARGER = check_pkt_larger(<var>L</var>); next;
       For distributed logical routers with distributed gateway port configured
       with <code>options:gateway_mtu</code> to a valid integer value, this
       table adds the following priority-50 logical flow for each
-      logical router port with the match <code>ip4 &amp;&amp;
-      inport == <var>LRP</var> &amp;&amp; outport == <var>GW_PORT</var>
-      &amp;&amp; REGBIT_PKT_LARGER</code>, where <var>LRP</var> is the logical
-      router port and <var>GW_PORT</var> is the distributed gateway router port
-      and applies the following action
+      logical router port with the match <code>inport == <var>LRP</var>
+      &amp;&amp; outport == <var>GW_PORT</var> &amp;&amp;
+      REGBIT_PKT_LARGER</code>, where <var>LRP</var> is the logical
+      router port and <var>GW_PORT</var> is the distributed gateway router
+      port and applies the following action for ipv4 and ipv6 respectively:
     </p>
 
     <pre>
@@ -2875,6 +2875,18 @@  icmp4 {
     REGBIT_EGRESS_LOOPBACK = 1;
     next(pipeline=ingress, table=0);
 };
+
+icmp6 {
+    icmp6.type = 2;
+    icmp6.code = 0;
+    icmp6.frag_mtu = <var>M</var>;
+    eth.dst = <var>E</var>;
+    ip6.dst = ip6.src;
+    ip6.src = <var>I</var>;
+    ip.ttl = 255;
+    REGBIT_EGRESS_LOOPBACK = 1;
+    next(pipeline=ingress, table=0);
+};
     </pre>
 
     <ul>
@@ -2890,7 +2902,7 @@  icmp4 {
       </li>
 
       <li>
-        <var>I</var> is the IPv4 address of the logical router port.
+        <var>I</var> is the IPv4/IPv6 address of the logical router port.
       </li>
     </ul>
 
diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c
index 417dbb603..234bbd99a 100644
--- a/northd/ovn-northd.c
+++ b/northd/ovn-northd.c
@@ -10117,8 +10117,7 @@  build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
             }
 
             ds_clear(&match);
-            ds_put_format(&match, "outport == %s && ip4",
-                          od->l3dgw_port->json_key);
+            ds_put_format(&match, "outport == %s", od->l3dgw_port->json_key);
 
             ds_clear(&actions);
             ds_put_format(&actions,
@@ -10131,34 +10130,65 @@  build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
             for (size_t i = 0; i < od->nbr->n_ports; i++) {
                 struct ovn_port *rp = ovn_port_find(ports,
                                                     od->nbr->ports[i]->name);
-                if (!rp || rp == od->l3dgw_port ||
-                    !rp->lrp_networks.ipv4_addrs) {
+                if (!rp || rp == od->l3dgw_port) {
                     continue;
                 }
-                ds_clear(&match);
-                ds_put_format(&match, "inport == %s && outport == %s && ip4 "
-                              "&& "REGBIT_PKT_LARGER,
-                              rp->json_key, od->l3dgw_port->json_key);
 
-                ds_clear(&actions);
-                /* Set icmp4.frag_mtu to gw_mtu */
-                ds_put_format(&actions,
-                    "icmp4_error {"
-                    REGBIT_EGRESS_LOOPBACK" = 1; "
-                    "eth.dst = %s; "
-                    "ip4.dst = ip4.src; "
-                    "ip4.src = %s; "
-                    "ip.ttl = 255; "
-                    "icmp4.type = 3; /* Destination Unreachable. */ "
-                    "icmp4.code = 4; /* Frag Needed and DF was Set. */ "
-                    "icmp4.frag_mtu = %d; "
-                    "next(pipeline=ingress, table=0); };",
-                    rp->lrp_networks.ea_s,
-                    rp->lrp_networks.ipv4_addrs[0].addr_s,
-                    gw_mtu);
-                ovn_lflow_add_with_hint(lflows, od, S_ROUTER_IN_LARGER_PKTS,
-                                        50, ds_cstr(&match), ds_cstr(&actions),
-                                        &rp->nbrp->header_);
+                if (rp->lrp_networks.ipv4_addrs) {
+                    ds_clear(&match);
+                    ds_put_format(&match, "inport == %s && outport == %s"
+                                  " && ip4 && "REGBIT_PKT_LARGER,
+                                  rp->json_key, od->l3dgw_port->json_key);
+
+                    ds_clear(&actions);
+                    /* Set icmp4.frag_mtu to gw_mtu */
+                    ds_put_format(&actions,
+                        "icmp4_error {"
+                        REGBIT_EGRESS_LOOPBACK" = 1; "
+                        "eth.dst = %s; "
+                        "ip4.dst = ip4.src; "
+                        "ip4.src = %s; "
+                        "ip.ttl = 255; "
+                        "icmp4.type = 3; /* Destination Unreachable. */ "
+                        "icmp4.code = 4; /* Frag Needed and DF was Set. */ "
+                        "icmp4.frag_mtu = %d; "
+                        "next(pipeline=ingress, table=0); };",
+                        rp->lrp_networks.ea_s,
+                        rp->lrp_networks.ipv4_addrs[0].addr_s,
+                        gw_mtu);
+                    ovn_lflow_add_with_hint(lflows, od,
+                                            S_ROUTER_IN_LARGER_PKTS, 50,
+                                            ds_cstr(&match), ds_cstr(&actions),
+                                            &rp->nbrp->header_);
+                }
+
+                if (rp->lrp_networks.ipv6_addrs) {
+                    ds_clear(&match);
+                    ds_put_format(&match, "inport == %s && outport == %s"
+                                  " && ip6 && "REGBIT_PKT_LARGER,
+                                  rp->json_key, od->l3dgw_port->json_key);
+
+                    ds_clear(&actions);
+                    /* Set icmp6.frag_mtu to gw_mtu */
+                    ds_put_format(&actions,
+                        "icmp6_error {"
+                        REGBIT_EGRESS_LOOPBACK" = 1; "
+                        "eth.dst = %s; "
+                        "ip6.dst = ip6.src; "
+                        "ip6.src = %s; "
+                        "ip.ttl = 255; "
+                        "icmp6.type = 2; "
+                        "icmp6.code = 0; "
+                        "icmp6.frag_mtu = %d; "
+                        "next(pipeline=ingress, table=0); };",
+                        rp->lrp_networks.ea_s,
+                        rp->lrp_networks.ipv6_addrs[0].addr_s,
+                        gw_mtu);
+                    ovn_lflow_add_with_hint(lflows, od,
+                                            S_ROUTER_IN_LARGER_PKTS, 50,
+                                            ds_cstr(&match), ds_cstr(&actions),
+                                            &rp->nbrp->header_);
+                }
             }
         }
     }
diff --git a/tests/ovn.at b/tests/ovn.at
index 124dd78d2..020ed17c0 100644
--- a/tests/ovn.at
+++ b/tests/ovn.at
@@ -15015,17 +15015,17 @@  ovn_start
 
 ovn-nbctl ls-add sw0
 ovn-nbctl lsp-add sw0 sw0-port1
-ovn-nbctl lsp-set-addresses sw0-port1 "50:54:00:00:00:01 10.0.0.3"
+ovn-nbctl lsp-set-addresses sw0-port1 "50:54:00:00:00:01 10.0.0.3 1000::3"
 
 ovn-nbctl lr-add lr0
-ovn-nbctl lrp-add lr0 lr0-sw0 00:00:00:00:ff:01 10.0.0.1/24
+ovn-nbctl lrp-add lr0 lr0-sw0 00:00:00:00:ff:01 10.0.0.1/24 1000::1/64
 ovn-nbctl lsp-add sw0 sw0-lr0
 ovn-nbctl lsp-set-type sw0-lr0 router
 ovn-nbctl lsp-set-addresses sw0-lr0 router
 ovn-nbctl lsp-set-options sw0-lr0 router-port=lr0-sw0
 
 ovn-nbctl ls-add public
-ovn-nbctl lrp-add lr0 lr0-public 00:00:20:20:12:13 172.168.0.100/24
+ovn-nbctl lrp-add lr0 lr0-public 00:00:20:20:12:13 172.168.0.100/24 2000::1/64
 ovn-nbctl lsp-add public public-lr0
 ovn-nbctl lsp-set-type public-lr0 router
 ovn-nbctl lsp-set-addresses public-lr0 router
@@ -15039,6 +15039,7 @@  ovn-nbctl lsp-set-options ln-public network_name=phys
 
 ovn-nbctl lrp-set-gateway-chassis lr0-public hv1 20
 ovn-nbctl lr-nat-add lr0 snat 172.168.0.100 10.0.0.0/24
+ovn-nbctl lr-nat-add lr0 snat 2000::1 1000::/64
 
 net_add n1
 
@@ -15149,6 +15150,41 @@  test_ip_packet_larger() {
     fi
 }
 
+test_ip6_packet_larger() {
+    local icmp_pmtu_reply_expected=$1
+
+    local eth_src=505400000001
+    local eth_dst=00000000ff01
+
+    local ipv6_src=10000000000000000000000000000003
+    local ipv6_dst=20000000000000000000000000000002
+    local ipv6_rt=10000000000000000000000000000001
+
+    local payload=0000000000000000000000000000000000000000
+    local payload=${payload}0000000000000000000000000000000000000000
+    local payload=${payload}0000000000000000000000000000000000000000
+    local payload=${payload}0000000000000000000000000000000000000000
+
+    local ip6_hdr=6000000000583aff${ipv6_src}${ipv6_dst}
+    local packet=${eth_dst}${eth_src}86dd${ip6_hdr}8000ec7662f00001${payload}
+
+    as hv1 reset_pcap_file br-phys_n1 hv1/br-phys_n1
+    as hv1 reset_pcap_file hv1-vif1 hv1/vif1
+
+    # Send packet from sw0-port1 to outside
+    as hv1 ovs-appctl netdev-dummy/receive hv1-vif1 $packet
+
+    if test $icmp_pmtu_reply_expected = 1; then
+        icmp6_reply=${eth_src}${eth_dst}86dd6000000000883afe
+        icmp6_reply=${icmp6_reply}${ipv6_rt}${ipv6_src}020041ff00000076
+        icmp6_reply=${icmp6_reply}6000000000583afe${ipv6_src}${ipv6_dst}
+        icmp6_reply=${icmp6_reply}8000ec7662f00001${payload}
+        echo $icmp6_reply > hv1-vif1.expected
+
+        OVN_CHECK_PACKETS([hv1/vif1-tx.pcap], [hv1-vif1.expected])
+    fi
+}
+
 ovn-nbctl show
 ovn-sbctl show
 
@@ -15183,6 +15219,12 @@  OVS_WAIT_UNTIL([
 # Now the packet should be sent via the localnet port to br-phys.
 icmp_reply_expected=0
 test_ip_packet_larger $icmp_reply_expected
+
+# Set the gateway mtu to 118
+ovn-nbctl --wait=hv set logical_router_port lr0-public options:gateway_mtu=118
+icmp_reply_expected=1
+test_ip6_packet_larger $icmp_reply_expected
+
 OVN_CLEANUP([hv1])
 AT_CLEANUP