zebra: Add functionality to parse RTM_NEWNEXTHOP and RTM_DELNEXTHOP messages

Add the functionality to parse new nexthop group messages
from the kernel and insert them into the appropriate hash
tables. Parsing is done at startup between interface and
interface address lookup. Add functionality to parse
changes to nexthops we already have. Add functionality
to parse delete nexthop messages from the kernel and
remove them from our table.

Signed-off-by: Stephen Worley <sworley@cumulusnetworks.com>

1 files changed, 288 insertions, 0 deletions

diff --git a/zebra/rt_netlink.c b/zebra/rt_netlink.c
index b36fbb2008..b30805b982 100644
--- a/zebra/rt_netlink.c
+++ b/zebra/rt_netlink.c
@@ -27,6 +27,7 @@
 #include <linux/mpls_iptunnel.h>
 #include <linux/neighbour.h>
 #include <linux/rtnetlink.h>
+#include <linux/nexthop.h>
 
 /* Hack for GNU libc version 2. */
 #ifndef MSG_TRUNC
@@ -62,6 +63,7 @@
 #include "zebra/zebra_mpls.h"
 #include "zebra/kernel_netlink.h"
 #include "zebra/rt_netlink.h"
+#include "zebra/zebra_nhg.h"
 #include "zebra/zebra_mroute.h"
 #include "zebra/zebra_vxlan.h"
 #include "zebra/zebra_errors.h"
@@ -1920,6 +1922,292 @@ enum zebra_dplane_result kernel_route_update(struct zebra_dplane_ctx *ctx)
 		ZEBRA_DPLANE_REQUEST_SUCCESS : ZEBRA_DPLANE_REQUEST_FAILURE);
 }
 
+/**
+ * netlink_nexthop_process_nh() - Parse the gatway/if info from a new nexthop
+ *
+ * @tb:		Netlink RTA data
+ * @family:	Address family in the nhmsg
+ * @ns_id:	Namspace id
+ *
+ * Return:	New nexthop
+ */
+static struct nexthop netlink_nexthop_process_nh(struct rtattr **tb,
+						 unsigned char family,
+						 ns_id_t ns_id)
+{
+	struct nexthop nh = {0};
+	void *gate = NULL;
+	struct interface *ifp = NULL;
+	int if_index;
+	size_t sz;
+
+	if_index = *(int *)RTA_DATA(tb[NHA_OIF]);
+
+	if (tb[NHA_GATEWAY]) {
+		switch (family) {
+		case AF_INET:
+			nh.type = NEXTHOP_TYPE_IPV4_IFINDEX;
+			sz = 4;
+			break;
+		case AF_INET6:
+			nh.type = NEXTHOP_TYPE_IPV6_IFINDEX;
+			sz = 16;
+			break;
+		default:
+			flog_warn(
+				EC_ZEBRA_BAD_NHG_MESSAGE,
+				"Nexthop with bad address family (%d) received from kernel",
+				family);
+			// TODO: Different return value?
+			return nh;
+		}
+		gate = RTA_DATA(tb[NHA_GATEWAY]);
+		memcpy(&(nh.gate), gate, sz);
+	} else {
+		nh.type = NEXTHOP_TYPE_IFINDEX;
+	}
+
+	nh.ifindex = if_index;
+
+	ifp = if_lookup_by_index_per_ns(zebra_ns_lookup(ns_id), nh.ifindex);
+	if (ifp) {
+		nh.vrf_id = ifp->vrf_id;
+	} else {
+		flog_warn(
+			EC_ZEBRA_UNKNOWN_INTERFACE,
+			"%s: Unknown nexthop interface %u received, defaulting to VRF_DEFAULT",
+			__PRETTY_FUNCTION__, nh.ifindex);
+
+		nh.vrf_id = VRF_DEFAULT;
+	}
+
+	if (tb[NHA_ENCAP] && tb[NHA_ENCAP_TYPE]) {
+		uint16_t encap_type = *(uint16_t *)RTA_DATA(tb[NHA_ENCAP_TYPE]);
+		int num_labels = 0;
+		mpls_label_t labels[MPLS_MAX_LABELS] = {0};
+
+		if (encap_type == LWTUNNEL_ENCAP_MPLS) {
+			num_labels = parse_encap_mpls(tb[NHA_ENCAP], labels);
+		}
+
+		if (num_labels) {
+			nexthop_add_labels(&nh, ZEBRA_LSP_STATIC, num_labels,
+					   labels);
+		}
+	}
+
+	return nh;
+}
+
+/**
+ * netlink_nexthop_process_group() - Iterate over nhmsg nexthop group
+ *
+ * @tb:		Netlink RTA data
+ *
+ * Return:	TODO: Not sure yet
+ */
+static int netlink_nexthop_process_group(struct rtattr **tb)
+{
+	int count;
+	struct nexthop_grp *n_grp = NULL;
+
+	n_grp = RTA_DATA(tb[NHA_GROUP]);
+	count = (RTA_PAYLOAD(tb[NHA_GROUP]) / sizeof(*n_grp));
+
+	if (!count || (count * sizeof(*n_grp)) != RTA_PAYLOAD(tb[NHA_GROUP])) {
+		flog_warn(EC_ZEBRA_BAD_NHG_MESSAGE,
+			  "Invalid nexthop group received from the kernel");
+		return -1;
+	}
+
+	// TODO: Need type for something?
+	// zlog_debug("group type: %d",
+	//	   *((uint16_t *)RTA_DATA(tb[NHA_GROUP_TYPE])));
+
+
+	for (int i = 0; i < count; i++) {
+		// TODO: Lookup by id and if we already have entries
+		// for that id, delete it?
+
+		/* We do not care about nexthop_grp.weight at
+		 * this time. But we should figure out
+		 * how to adapt this to our code in
+		 * the future.
+		 */
+	}
+
+	return count;
+}
+
+/**
+ * netlink_nexthop_change() - Read in change about nexthops from the kernel
+ *
+ * @h:		Netlink message header
+ * @ns_id:	Namspace id
+ * @startup:	Are we reading under startup conditions?
+ *
+ * Return:	Result status
+ */
+int netlink_nexthop_change(struct nlmsghdr *h, ns_id_t ns_id, int startup)
+{
+	int len;
+	/* nexthop group id */
+	uint32_t id;
+	unsigned char family;
+	struct nhmsg *nhm = NULL;
+	/* struct for nexthop group abstraction  */
+	struct nexthop_group nhg = {0};
+	/* zebra's version of nexthops */
+	struct nexthop nh = {0};
+	/* struct that goes into our tables */
+	struct nhg_hash_entry *nhe = NULL;
+	struct rtattr *tb[NHA_MAX + 1];
+
+
+	nhm = NLMSG_DATA(h);
+
+	if (startup && h->nlmsg_type != RTM_NEWNEXTHOP)
+		return 0;
+
+	len = h->nlmsg_len - NLMSG_LENGTH(sizeof(struct nhmsg));
+	if (len < 0) {
+		zlog_warn(
+			"%s: Message received from netlink is of a broken size %d %zu",
+			__PRETTY_FUNCTION__, h->nlmsg_len,
+			(size_t)NLMSG_LENGTH(sizeof(struct nhmsg)));
+		return -1;
+	}
+
+	memset(tb, 0, sizeof(tb));
+	netlink_parse_rtattr(tb, NHA_MAX, RTM_NHA(nhm), len);
+
+
+	if (!tb[NHA_ID]) {
+		flog_warn(
+			EC_ZEBRA_BAD_NHG_MESSAGE,
+			"Nexthop group without an ID received from the kernel");
+		return -1;
+	}
+
+	/* We use the ID key'd nhg table for kernel updates */
+	id = *((uint32_t *)RTA_DATA(tb[NHA_ID]));
+	family = nhm->nh_family;
+
+	if (IS_ZEBRA_DEBUG_KERNEL) {
+		zlog_debug("Nexthop ID (%u) update from the kernel", id);
+	}
+
+	/* Lookup via the id */
+	nhe = zebra_nhg_lookup_id(id);
+
+	if (h->nlmsg_type == RTM_NEWNEXTHOP) {
+		if (tb[NHA_GROUP]) {
+			/**
+			 * If this is a group message its only going to have
+			 * an array of nexthop IDs associated with it
+			 */
+			return -1;
+			netlink_nexthop_process_group(tb);
+		} else if (tb[NHA_BLACKHOLE]) {
+			/**
+			 * This nexthop is just for blackhole-ing traffic,
+			 * it should not have an OIF, GATEWAY, or ENCAP
+			 */
+			nh.type = NEXTHOP_TYPE_BLACKHOLE;
+			// TODO: Handle blackhole case
+			nh.bh_type = BLACKHOLE_UNSPEC;
+		} else if (tb[NHA_OIF]) {
+			/**
+			 * This is a true new nexthop, so we need
+			 * to parse the gateway and device info
+			 */
+			nh = netlink_nexthop_process_nh(tb, family, ns_id);
+		}
+
+
+		nexthop_group_add_sorted(&nhg, &nh);
+
+		if (nhe) {
+			/* This is a change to a group we already have */
+			nexthops_free(nhe->nhg.nexthop);
+			nhe->nhg.nexthop = NULL;
+			nexthop_group_copy(&nhe->nhg, &nhg);
+		} else {
+			/* This is a new nexthop group */
+			nhe = zebra_nhg_find(&nhg, nh.vrf_id, id);
+			if (nhe) {
+				nhe->is_kernel_nh = true;
+			} else {
+				return -1;
+			}
+		}
+	} else if (h->nlmsg_type == RTM_DELNEXTHOP) {
+		if (!nhe) {
+			flog_warn(
+				EC_ZEBRA_BAD_NHG_MESSAGE,
+				"Kernel delete message received for nexthop group ID (%u) that we do not have in our ID table",
+				id);
+			return -1;
+		}
+
+		// TODO: Run some active check on all route_entry's?
+		zebra_nhg_release(nhe);
+	}
+
+
+	return 0;
+}
+
+/**
+ * netlink_request_nexthop() - Request nextop information from the kernel
+ * @zns:	Zebra namespace
+ * @family:	AF_* netlink family
+ * @type:	RTM_* route type
+ *
+ * Return:	Result status
+ */
+static int netlink_request_nexthop(struct zebra_ns *zns, int family, int type)
+{
+	struct {
+		struct nlmsghdr n;
+		struct nhmsg nhm;
+	} req;
+
+	/* Form the request, specifying filter (rtattr) if needed. */
+	memset(&req, 0, sizeof(req));
+	req.n.nlmsg_type = type;
+	req.n.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
+	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct nhmsg));
+	req.nhm.nh_family = family;
+
+	return netlink_request(&zns->netlink_cmd, &req.n);
+}
+
+/**
+ * netlink_nexthop_read() - Nexthop read function using netlink interface
+ *
+ * @zns:	Zebra name space
+ *
+ * Return:	Result status
+ * Only called at bootstrap time.
+ */
+int netlink_nexthop_read(struct zebra_ns *zns)
+{
+	int ret;
+	struct zebra_dplane_info dp_info;
+
+	zebra_dplane_info_from_zns(&dp_info, zns, true /*is_cmd*/);
+
+	/* Get nexthop objects */
+	ret = netlink_request_nexthop(zns, AF_UNSPEC, RTM_GETNEXTHOP);
+	if (ret < 0)
+		return ret;
+	ret = netlink_parse_info(netlink_nexthop_change, &zns->netlink_cmd,
+				 &dp_info, 0, 1);
+	return 0;
+}
+
+
 int kernel_neigh_update(int add, int ifindex, uint32_t addr, char *lla,
 			int llalen, ns_id_t ns_id)
 {