zebra: ZEBRA_ROUTE_ADD supports seg6 route (step3)

With this patch, zclient can intall seg6 rotues when
they set properties "nh_seg6_segs" on struct nexthop
and set ZEBRA_FLAG_SEG6_ROUTE on zapi_route's flag.

Signed-off-by: Hiroki Shirokura <slank.dev@gmail.com>

zebra/rt_netlink.c

@@ -1286,6 +1286,26 @@ static bool _netlink_route_encode_nexthop_src(const struct nexthop *nexthop,
 	return true;
 }
 
+static size_t fill_seg6ipt_encap(char *buffer, size_t buflen,
+				 struct in6_addr *seg)
+{
+	struct seg6_iptunnel_encap *ipt;
+	struct ipv6_sr_hdr *srh;
+	const size_t srhlen = 24;
+	memset(buffer, 0, buflen);
+
+	ipt = (struct seg6_iptunnel_encap *)buffer;
+	ipt->mode = SEG6_IPTUN_MODE_ENCAP;
+	srh = ipt->srh;
+	srh->hdrlen = (srhlen >> 3) - 1;
+	srh->type = 4;
+	srh->segments_left = 0;
+	srh->first_segment = 0;
+	memcpy(&srh->segments[0], seg, sizeof(struct in6_addr));
+
+	return srhlen + 4;
+}
+
 /* This function takes a nexthop as argument and adds
  * the appropriate netlink attributes to an existing
  * netlink message.
@@ -1367,6 +1387,21 @@ static bool _netlink_route_build_singlepath(const struct prefix *p,
 		nl_attr_nest_end(nlmsg, nest);
 	}
 
+	if (nexthop->nh_seg6_segs) {
+		char tun_buf[4096];
+		size_t tun_len;
+		struct rtattr *nest;
+
+		nl_attr_put16(nlmsg, req_size, RTA_ENCAP_TYPE,
+			      LWTUNNEL_ENCAP_SEG6);
+		nest = nl_attr_nest(nlmsg, req_size, RTA_ENCAP);
+		tun_len = fill_seg6ipt_encap(tun_buf, sizeof(tun_buf),
+					     nexthop->nh_seg6_segs);
+		nl_attr_put(nlmsg, req_size, SEG6_IPTUNNEL_SRH,
+			    tun_buf, tun_len);
+		nl_attr_nest_end(nlmsg, nest);
+	}
+
 	if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ONLINK))
 		rtmsg->rtm_flags |= RTNH_F_ONLINK;
 
@@ -2422,6 +2457,23 @@ ssize_t netlink_nexthop_msg_encode(uint16_t cmd,
 				nl_attr_nest_end(&req->n, nest);
 			}
 
+			if (nh->nh_seg6_segs) {
+				char tun_buf[4096];
+				size_t tun_len;
+				struct rtattr *nest;
+
+				nl_attr_put16(&req->n, buflen, NHA_ENCAP_TYPE,
+					      LWTUNNEL_ENCAP_SEG6);
+				nest = nl_attr_nest(&req->n, buflen,
+						    NHA_ENCAP | NLA_F_NESTED);
+				tun_len = fill_seg6ipt_encap(tun_buf,
+						sizeof(tun_buf),
+						nh->nh_seg6_segs);
+				nl_attr_put(&req->n, buflen, SEG6_IPTUNNEL_SRH,
+						tun_buf, tun_len);
+				nl_attr_nest_end(&req->n, nest);
+			}
+
 nexthop_done:
 
 			if (IS_ZEBRA_DEBUG_KERNEL)

zebra/zapi_msg.c

@@ -1783,6 +1783,14 @@ static bool zapi_read_nexthops(struct zserv *client, struct prefix *p,
 					      &api_nh->seg6local_ctx);
 		}
 
+		if (CHECK_FLAG(flags, ZEBRA_FLAG_SEG6_ROUTE)
+		    && api_nh->type != NEXTHOP_TYPE_BLACKHOLE) {
+			if (IS_ZEBRA_DEBUG_RECV)
+				zlog_debug("%s: adding seg6", __func__);
+
+			nexthop_add_seg6(nexthop, &api_nh->seg6_segs);
+		}
+
 		if (IS_ZEBRA_DEBUG_RECV) {
 			labelbuf[0] = '\0';
 			nhbuf[0] = '\0';

zebra/zebra_nhg.c

@@ -1008,6 +1008,7 @@ void nhg_ctx_free(struct nhg_ctx **ctx)
 
 	nexthop_del_labels(nh);
 	nexthop_del_seg6local(nh);
+	nexthop_del_seg6(nh);
 
 done:
 	XFREE(MTYPE_NHG_CTX, *ctx);
@@ -1379,6 +1380,7 @@ static struct nhg_hash_entry *depends_find_singleton(const struct nexthop *nh,
 	/* The copy may have allocated labels; free them if necessary. */
 	nexthop_del_labels(&lookup);
 	nexthop_del_seg6local(&lookup);
+	nexthop_del_seg6(&lookup);
 
 	if (IS_ZEBRA_DEBUG_NHG_DETAIL)
 		zlog_debug("%s: nh %pNHv => %p (%u)",

zebra/zebra_vty.c

@@ -662,6 +662,11 @@ static void show_route_nexthop_helper(struct vty *vty,
 			buf);
 	}
 
+	if (nexthop->nh_seg6_segs) {
+		inet_ntop(AF_INET6, nexthop->nh_seg6_segs, buf, sizeof(buf));
+		vty_out(vty, ", seg6 %s", buf);
+	}
+
 	if (nexthop->weight)
 		vty_out(vty, ", weight %u", nexthop->weight);
 
@@ -685,6 +690,7 @@ static void show_nexthop_json_helper(json_object *json_nexthop,
 	json_object *json_labels = NULL;
 	json_object *json_backups = NULL;
 	json_object *json_seg6local = NULL;
+	json_object *json_seg6 = NULL;
 	int i;
 
 	json_object_int_add(json_nexthop, "flags",
@@ -871,6 +877,13 @@ static void show_nexthop_json_helper(json_object *json_nexthop,
 		json_object_object_add(json_nexthop, "seg6local",
 				       json_seg6local);
 	}
+
+	if (nexthop->nh_seg6_segs) {
+		json_seg6 = json_object_new_object();
+		inet_ntop(AF_INET6, nexthop->nh_seg6_segs, buf, sizeof(buf));
+		json_object_string_add(json_seg6, "segs", buf);
+		json_object_object_add(json_nexthop, "seg6", json_seg6);
+	}
 }
 
 static void vty_show_ip_route(struct vty *vty, struct route_node *rn,