1 files changed, 293 insertions, 0 deletions
diff --git a/nhrpd/nhrp_multicast.c b/nhrpd/nhrp_multicast.c
new file mode 100644
index 0000000..fdc1a31
--- /dev/null
+++ b/nhrpd/nhrp_multicast.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* NHRP Multicast Support
+ * Copyright (c) 2020-2021 4RF Limited
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <fcntl.h>
+#include <net/if.h>
+#include <net/ethernet.h>
+#include <netinet/if_ether.h>
+#include <linux/netlink.h>
+#include <linux/neighbour.h>
+#include <linux/netfilter/nfnetlink_log.h>
+#include <linux/if_packet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include "frrevent.h"
+#include "nhrpd.h"
+#include "netlink.h"
+#include "znl.h"
+#include "os.h"
+
+DEFINE_MTYPE_STATIC(NHRPD, NHRP_MULTICAST, "NHRP Multicast");
+
+int netlink_mcast_nflog_group;
+static int netlink_mcast_log_fd = -1;
+static struct event *netlink_mcast_log_thread;
+
+struct mcast_ctx {
+	struct interface *ifp;
+	struct zbuf *pkt;
+};
+
+static void nhrp_multicast_send(struct nhrp_peer *p, struct zbuf *zb)
+{
+	size_t addrlen;
+	int ret;
+
+	addrlen = sockunion_get_addrlen(&p->vc->remote.nbma);
+	ret = os_sendmsg(zb->head, zbuf_used(zb), p->ifp->ifindex,
+			 sockunion_get_addr(&p->vc->remote.nbma), addrlen,
+			 addrlen == 4 ? ETH_P_IP : ETH_P_IPV6);
+
+	debugf(NHRP_DEBUG_COMMON,
+	       "Multicast Packet: %pSU -> %pSU, ret = %d, size = %zu, addrlen = %zu",
+	       &p->vc->local.nbma, &p->vc->remote.nbma, ret, zbuf_used(zb),
+	       addrlen);
+}
+
+static void nhrp_multicast_forward_nbma(union sockunion *nbma_addr,
+					struct interface *ifp, struct zbuf *pkt)
+{
+	struct nhrp_peer *p = nhrp_peer_get(ifp, nbma_addr);
+
+	if (p && p->online) {
+		/* Send packet */
+		nhrp_multicast_send(p, pkt);
+	}
+	nhrp_peer_unref(p);
+}
+
+static void nhrp_multicast_forward_cache(struct nhrp_cache *c, void *pctx)
+{
+	struct mcast_ctx *ctx = (struct mcast_ctx *)pctx;
+
+	if (c->cur.type == NHRP_CACHE_DYNAMIC && c->cur.peer)
+		nhrp_multicast_forward_nbma(&c->cur.peer->vc->remote.nbma,
+					    ctx->ifp, ctx->pkt);
+}
+
+static void nhrp_multicast_forward(struct nhrp_multicast *mcast, void *pctx)
+{
+	struct mcast_ctx *ctx = (struct mcast_ctx *)pctx;
+	struct nhrp_interface *nifp = ctx->ifp->info;
+
+	if (!nifp->enabled)
+		return;
+
+	/* dynamic */
+	if (sockunion_family(&mcast->nbma_addr) == AF_UNSPEC) {
+		nhrp_cache_foreach(ctx->ifp, nhrp_multicast_forward_cache,
+				   pctx);
+		return;
+	}
+
+	/* Fixed IP Address */
+	nhrp_multicast_forward_nbma(&mcast->nbma_addr, ctx->ifp, ctx->pkt);
+}
+
+static void netlink_mcast_log_handler(struct nlmsghdr *msg, struct zbuf *zb)
+{
+	struct nfgenmsg *nf;
+	struct rtattr *rta;
+	struct zbuf rtapl;
+	uint32_t *out_ndx = NULL;
+	afi_t afi;
+	struct mcast_ctx ctx;
+
+	nf = znl_pull(zb, sizeof(*nf));
+	if (!nf)
+		return;
+
+	ctx.pkt = NULL;
+	while ((rta = znl_rta_pull(zb, &rtapl)) != NULL) {
+		switch (rta->rta_type) {
+		case NFULA_IFINDEX_OUTDEV:
+			out_ndx = znl_pull(&rtapl, sizeof(*out_ndx));
+			break;
+		case NFULA_PAYLOAD:
+			ctx.pkt = &rtapl;
+			break;
+			/* NFULA_HWHDR exists and is supposed to contain source
+			 * hardware address. However, for ip_gre it seems to be
+			 * the nexthop destination address if the packet matches
+			 * route.
+			 */
+		}
+	}
+
+	if (!out_ndx || !ctx.pkt)
+		return;
+
+	ctx.ifp = if_lookup_by_index(htonl(*out_ndx), VRF_DEFAULT);
+	if (!ctx.ifp)
+		return;
+
+	debugf(NHRP_DEBUG_COMMON,
+	       "Intercepted multicast packet leaving %s len %zu",
+	       ctx.ifp->name, zbuf_used(ctx.pkt));
+
+	for (afi = 0; afi < AFI_MAX; afi++) {
+		nhrp_multicast_foreach(ctx.ifp, afi, nhrp_multicast_forward,
+				       (void *)&ctx);
+	}
+}
+
+static void netlink_mcast_log_recv(struct event *t)
+{
+	uint8_t buf[65535]; /* Max OSPF Packet size */
+	int fd = EVENT_FD(t);
+	struct zbuf payload, zb;
+	struct nlmsghdr *n;
+
+
+	zbuf_init(&zb, buf, sizeof(buf), 0);
+	while (zbuf_recv(&zb, fd) > 0) {
+		while ((n = znl_nlmsg_pull(&zb, &payload)) != NULL) {
+			debugf(NHRP_DEBUG_COMMON,
+			       "Netlink-mcast-log: Received msg_type %u, msg_flags %u",
+			       n->nlmsg_type, n->nlmsg_flags);
+			switch (n->nlmsg_type) {
+			case (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_PACKET:
+				netlink_mcast_log_handler(n, &payload);
+				break;
+			}
+		}
+	}
+
+	event_add_read(master, netlink_mcast_log_recv, 0, netlink_mcast_log_fd,
+		       &netlink_mcast_log_thread);
+}
+
+static void netlink_mcast_log_register(int fd, int group)
+{
+	struct nlmsghdr *n;
+	struct nfgenmsg *nf;
+	struct nfulnl_msg_config_cmd cmd;
+	struct zbuf *zb = zbuf_alloc(512);
+
+	n = znl_nlmsg_push(zb, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG,
+			   NLM_F_REQUEST | NLM_F_ACK);
+	nf = znl_push(zb, sizeof(*nf));
+	*nf = (struct nfgenmsg){
+		.nfgen_family = AF_UNSPEC,
+		.version = NFNETLINK_V0,
+		.res_id = htons(group),
+	};
+	cmd.command = NFULNL_CFG_CMD_BIND;
+	znl_rta_push(zb, NFULA_CFG_CMD, &cmd, sizeof(cmd));
+	znl_nlmsg_complete(zb, n);
+
+	zbuf_send(zb, fd);
+	zbuf_free(zb);
+}
+
+void netlink_mcast_set_nflog_group(int nlgroup)
+{
+	if (netlink_mcast_log_fd >= 0) {
+		EVENT_OFF(netlink_mcast_log_thread);
+		close(netlink_mcast_log_fd);
+		netlink_mcast_log_fd = -1;
+		debugf(NHRP_DEBUG_COMMON, "De-register nflog group");
+	}
+	netlink_mcast_nflog_group = nlgroup;
+	if (nlgroup) {
+		netlink_mcast_log_fd = znl_open(NETLINK_NETFILTER, 0);
+		if (netlink_mcast_log_fd < 0)
+			return;
+
+		netlink_mcast_log_register(netlink_mcast_log_fd, nlgroup);
+		event_add_read(master, netlink_mcast_log_recv, 0,
+			       netlink_mcast_log_fd, &netlink_mcast_log_thread);
+		debugf(NHRP_DEBUG_COMMON, "Register nflog group: %d",
+		       netlink_mcast_nflog_group);
+	}
+}
+
+static int nhrp_multicast_free(struct interface *ifp,
+			       struct nhrp_multicast *mcast)
+{
+	struct nhrp_interface *nifp = ifp->info;
+
+	nhrp_mcastlist_del(&nifp->afi[mcast->afi].mcastlist_head, mcast);
+	XFREE(MTYPE_NHRP_MULTICAST, mcast);
+	return 0;
+}
+
+int nhrp_multicast_add(struct interface *ifp, afi_t afi,
+		       union sockunion *nbma_addr)
+{
+	struct nhrp_interface *nifp = ifp->info;
+	struct nhrp_multicast *mcast;
+
+	frr_each (nhrp_mcastlist, &nifp->afi[afi].mcastlist_head, mcast) {
+		if (sockunion_same(&mcast->nbma_addr, nbma_addr))
+			return NHRP_ERR_ENTRY_EXISTS;
+	}
+
+	mcast = XMALLOC(MTYPE_NHRP_MULTICAST, sizeof(struct nhrp_multicast));
+
+	*mcast = (struct nhrp_multicast){
+		.afi = afi, .ifp = ifp, .nbma_addr = *nbma_addr,
+	};
+	nhrp_mcastlist_add_tail(&nifp->afi[afi].mcastlist_head, mcast);
+
+	debugf(NHRP_DEBUG_COMMON, "Adding multicast entry (%pSU)", nbma_addr);
+
+	return NHRP_OK;
+}
+
+int nhrp_multicast_del(struct interface *ifp, afi_t afi,
+		       union sockunion *nbma_addr)
+{
+	struct nhrp_interface *nifp = ifp->info;
+	struct nhrp_multicast *mcast;
+
+	frr_each_safe (nhrp_mcastlist, &nifp->afi[afi].mcastlist_head, mcast) {
+		if (!sockunion_same(&mcast->nbma_addr, nbma_addr))
+			continue;
+
+		debugf(NHRP_DEBUG_COMMON, "Deleting multicast entry (%pSU)",
+		       nbma_addr);
+
+		nhrp_multicast_free(ifp, mcast);
+
+		return NHRP_OK;
+	}
+
+	return NHRP_ERR_ENTRY_NOT_FOUND;
+}
+
+void nhrp_multicast_interface_del(struct interface *ifp)
+{
+	struct nhrp_interface *nifp = ifp->info;
+	struct nhrp_multicast *mcast;
+	afi_t afi;
+
+	for (afi = 0; afi < AFI_MAX; afi++) {
+		debugf(NHRP_DEBUG_COMMON, "Cleaning up multicast entries (%zu)",
+		       nhrp_mcastlist_count(&nifp->afi[afi].mcastlist_head));
+
+		frr_each_safe (nhrp_mcastlist, &nifp->afi[afi].mcastlist_head,
+			       mcast) {
+			nhrp_multicast_free(ifp, mcast);
+		}
+	}
+}
+
+void nhrp_multicast_foreach(struct interface *ifp, afi_t afi,
+			    void (*cb)(struct nhrp_multicast *, void *),
+			    void *ctx)
+{
+	struct nhrp_interface *nifp = ifp->info;
+	struct nhrp_multicast *mcast;
+
+	frr_each (nhrp_mcastlist, &nifp->afi[afi].mcastlist_head, mcast) {
+		cb(mcast, ctx);
+	}
+}