digipeater: improve beacon handling

impl/src/layer2/connection.c

@@ -449,8 +449,6 @@ void connection_handle_ack(connection_ctx_t *ctx, uint8_t acked_seq, bool do_ack
 			break;
 	}
 
-	ctx->next_packet_index = 0;
-
 	size_t packets_to_remove = 0;
 	size_t packets_available = packet_queue_get_used_space(&ctx->packet_queue);
 
@@ -464,13 +462,21 @@ void connection_handle_ack(connection_ctx_t *ctx, uint8_t acked_seq, bool do_ack
 		packets_to_remove++;
 	}
 
+	if(packets_to_remove != 0) {
 		packet_queue_delete(&ctx->packet_queue, packets_to_remove);
 
+		// send the next requested packet (all previous ones were deleted above).
+		assert(ctx->next_packet_index >= packets_to_remove);
+		ctx->next_packet_index -= packets_to_remove;
+
 		packets_available = packet_queue_get_used_space(&ctx->packet_queue);
 
 		LOG(LVL_DEBUG, "handling ack for seq_nr %u, removed %zu packets, %zu packets remaining.", acked_seq, packets_to_remove, packets_available);
 
 		ctx->retransmit_time = get_hires_time() + HRTIME_MS(RETRANSMIT_TIMEOUT_MS);
+	} else {
+		LOG(LVL_DEBUG, "duplicate ACK for seq_nr %u", acked_seq);
+	}
 
 	if(do_ack && packets_available == 0) {
 		// no packets left in queue, but an acknowledgement must be

impl/src/layer2/digipeater.c

@@ -79,6 +79,25 @@ static result_t digipeater_handle_beacon_responses(digipeater_ctx_t *ctx, const
 }
 
 
+static size_t encode_beacon_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t buf_len)
+{
+	// build a beacon packet
+	layer2_packet_header_t header;
+
+	ham64_t broadcast = {{0xFFFF, 0, 0, 0}, 1};
+
+	header.dst_addr = broadcast;
+	header.src_addr = ctx->my_addr;
+	header.msg_type = L2_MSG_TYPE_CONN_MGMT;
+	header.rx_seq_nr = 0; // unused
+	header.tx_seq_nr = 0; // unused
+	header.tx_request = 1;
+
+	uint8_t payload[1] = {CONN_MGMT_TYPE_BEACON};
+	return layer2_encode_packet(&header, payload, 1, buf, buf_len);
+}
+
+
 result_t digipeater_init(digipeater_ctx_t *ctx, const ham64_t *my_addr, digipeater_data_callback_t data_cb)
 {
 	ctx->my_addr = *my_addr;
@@ -239,31 +258,11 @@ result_t digipeater_fill_packet_queues_from_tundev(digipeater_ctx_t *ctx, int tu
 size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t buf_len, bool *end_burst)
 {
 	uint64_t now = get_hires_time();
+
 	size_t packet_size = 0;
 
 	*end_burst = false;
 
-	if(now > ctx->next_beacon_time) {
-		// build a beacon packet
-		layer2_packet_header_t header;
-
-		ham64_t broadcast = {{0xFFFF, 0, 0, 0}, 1};
-
-		header.dst_addr = broadcast;
-		header.src_addr = ctx->my_addr;
-		header.msg_type = L2_MSG_TYPE_CONN_MGMT;
-		header.rx_seq_nr = 0; // unused
-		header.tx_seq_nr = 0; // unused
-		header.tx_request = 1;
-
-		uint8_t payload[1] = {CONN_MGMT_TYPE_BEACON};
-		packet_size = layer2_encode_packet(&header, payload, 1, buf, buf_len);
-
-		ctx->state = DIGIPEATER_STATE_BEACON;
-		*end_burst = true;
-		return packet_size;
-	}
-
 	// send packets from the one-shot queue
 	const packet_queue_entry_t *queue_entry = packet_queue_get(&ctx->oneshot_queue, 0);
 	if(queue_entry) {
@@ -275,8 +274,14 @@ size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t
 		}
 	}
 
-	// pull packets from the current connection
+	switch(ctx->state) {
+		case DIGIPEATER_STATE_BEACON:
+			packet_size = encode_beacon_packet(ctx, buf, buf_len);
+			*end_burst = true;
+			break;
 
+		case DIGIPEATER_STATE_CONN: {
+				// pull packets from the current connection
 				connection_list_entry_t *head = connection_list_get_head(&ctx->conn_list);
 				if(!head) {
 					return 0;
@@ -288,6 +293,9 @@ size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t
 
 					ctx->state = DIGIPEATER_STATE_CONN;
 				}
+			}
+			break;
+	}
 
 	return packet_size;
 }
@@ -301,6 +309,10 @@ bool digipeater_can_transmit(digipeater_ctx_t *ctx)
 		return true;
 	}
 
+	if(packet_queue_get_used_space(&ctx->oneshot_queue) != 0) {
+		return true;
+	}
+
 	connection_list_entry_t *head = connection_list_get_head(&ctx->conn_list);
 	if(head) {
 		return connection_can_transmit(&head->connection);
@@ -320,12 +332,17 @@ result_t digipeater_end_interval(digipeater_ctx_t *ctx)
 {
 	uint64_t now = get_hires_time();
 
+	if(now >= ctx->next_beacon_time) {
+		ctx->next_beacon_time += HRTIME_MS(BEACON_INTERVAL_MS);
+		ctx->state = DIGIPEATER_STATE_BEACON;
+	} else {
 		// TODO: adjust the time based on connection activity; right now this results
 		// in round-robin scheduling
 		connection_list_reschedule_head(&ctx->conn_list, now + HRTIME_MS(MIN_INTERVAL_TIME_MS));
 
 		ctx->state = DIGIPEATER_STATE_CONN;
 		ctx->interval_end_time = now + HRTIME_MS(MIN_INTERVAL_TIME_MS);
+	}
 
 	return OK;
 }

impl/src/layer2/digipeater.h

@@ -23,6 +23,7 @@ typedef enum {
 } digipeater_state_t;
 
 typedef enum {
+	// FIXME: rename to Cycle
 	DIGIPEATER_EVT_INTERVAL_END, //!< The current interval has ended and new packets should be transmitted.
 } digipeater_evt_t;