4 files changed, 46 insertions, 0 deletions

diff --git a/ffd/ffd.c b/ffd/ffd.c
index 5f17446..ccba14d 100644
--- a/ffd/ffd.c
+++ b/ffd/ffd.c
@@ -191,6 +191,17 @@ static inline ffd_neigh_t* get_tlv_neigh(handle_tlv_arg_t *arg) {
 	return ffd_neigh_get(arg->iface, arg->addr);
 }
 
+static void handle_tlv_ack_req(const ffd_tlv_ack_req_t *tlv_req, size_t len, handle_tlv_arg_t *arg) {
+	if (len < sizeof(ffd_tlv_ack_req_t)) {
+		fprintf(stderr, "warn: received short acknowledement request TLV.\n");
+		return;
+	}
+
+	ffd_neigh_t *neigh = get_tlv_neigh(arg);
+
+	ffd_send_ack(arg->iface, neigh, ntohs(tlv_req->nonce));
+}
+
 static void handle_tlv_hello(const ffd_tlv_hello_t *tlv_hello, size_t len, handle_tlv_arg_t *arg) {
 	if (len < sizeof(ffd_tlv_hello_t)) {
 		fprintf(stderr, "warn: received short hello TLV.\n");
@@ -392,6 +403,14 @@ static void handle_tlv_announce_req(const ffd_tlv_announce_req_t *tlv_req, size_
 
 static void handle_tlv(ffd_tlv_type_t type, const void *data, size_t len, void *arg) {
 	switch (type) {
+	case TLV_ACK_REQ:
+		handle_tlv_ack_req(data, len, arg);
+		return;
+
+	case TLV_ACK:
+		/* we don't send ack reqs */
+		return;
+
 	case TLV_HELLO:
 		handle_tlv_hello(data, len, arg);
 		return;
diff --git a/ffd/ffd.h b/ffd/ffd.h
index e0f1954..a93c855 100644
--- a/ffd/ffd.h
+++ b/ffd/ffd.h
@@ -152,6 +152,7 @@ ffd_metric_seqno_t ffd_announce_get_metric(const ffd_announce_t *announce);
 void ffd_announce_update_nexthop(ffd_announce_t *announce);
 ffd_announce_t* ffd_announce_new(void);
 
+void ffd_send_ack(ffd_iface_t *iface, ffd_neigh_t *neigh, uint16_t nonce);
 void ffd_send_hellos(void);
 void ffd_send_update(ffd_iface_t *iface, ffd_neigh_t *neigh, ffd_announce_t *announce, bool with_data);
 void ffd_send_announce_request(ffd_iface_t *iface, ffd_neigh_t *neigh, ffd_node_id_t node, uint16_t type, uint16_t key, bool with_data);
diff --git a/ffd/send.c b/ffd/send.c
index 48c44fc..779476b 100644
--- a/ffd/send.c
+++ b/ffd/send.c
@@ -72,6 +72,22 @@ static bool send_eth(const eth_addr_t *addr, unsigned ifindex, void *buf, size_t
 	return true;
 }
 
+void ffd_send_ack(ffd_iface_t *iface, ffd_neigh_t *neigh, uint16_t nonce) {
+	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);
+
+	packet->version_magic = htons(FFD_VERSION_MAGIC);
+	packet->len = 0;
+
+	ffd_tlv_ack_t *ack = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_ACK, sizeof(ffd_tlv_ack_t));
+	if (!ack)
+		return;
+
+	ack->nonce = htons(nonce);
+
+	if (!send_eth(&neigh->addr, iface->ifindex, packet, sizeof(ffd_packet_t)+ntohs(packet->len)))
+		fprintf(stderr, "send_eth: %m\n");
+}
+
 static void add_ihus(ffd_packet_t *packet, size_t max_len, const ffd_iface_t *iface) {
 	const ffd_neigh_t *neigh;
 
diff --git a/ffd/tlv_types.h b/ffd/tlv_types.h
index afe793a..07eba53 100644
--- a/ffd/tlv_types.h
+++ b/ffd/tlv_types.h
@@ -30,6 +30,16 @@
 #include "tlv.h"
 
 
+typedef struct __attribute__((packed)) _ffd_tlv_ack_req_t {
+	uint16_t reserved;
+	uint16_t nonce;
+	uint16_t interval;
+} ffd_tlv_ack_req_t;
+
+typedef struct __attribute__((packed)) _ffd_tlv_ack_t {
+	uint16_t nonce;
+} ffd_tlv_ack_t;
+
 typedef struct __attribute__((packed)) _ffd_tlv_hello_t {
 	uint16_t reserved;
 	uint16_t seqno;