impl/src/layer2/digipeater.c

@@ -1,5 +1,4 @@
-#include <string.h>
-#include <assert.h>
+#include "layer2/packet_queue.h"
 
 #define LOGGER_MODULE_NAME "digi"
 #include "logger.h"
@@ -83,9 +82,13 @@ result_t digipeater_init(digipeater_ctx_t *ctx, const ham64_t *my_addr, digipeat
 
 	ctx->state = DIGIPEATER_STATE_CONN;
 
+	packet_queue_init(&ctx->oneshot_queue);
+
 	uint64_t now = get_hires_time();
 	ctx->next_beacon_time = now + HRTIME_MS(BEACON_INTERVAL_MS);
 
+	ctx->interval_end_time = now;
+
 	return connection_list_init(&ctx->conn_list);
 }
 
@@ -135,31 +138,40 @@ result_t digipeater_handle_packet(digipeater_ctx_t *ctx, const uint8_t *buf, siz
 		return ERR_INVALID_ADDRESS;
 	}
 
-	// FIXME: handle connection management packets here
+	// FIXME: handle connection management packets here (or somewhere else):
+	// - Disconnect Request
 
 	size_t header_size = layer2_get_encoded_header_size(&header);
 
 	const uint8_t *payload = buf + header_size;
 	size_t payload_len = packet_size - header_size;
 
+	result_t result = OK;
+
 	switch(ctx->state) {
 		case DIGIPEATER_STATE_CONN:
 			{
 				connection_list_entry_t *head = connection_list_get_head(&ctx->conn_list);
 				if(head) {
 					connection_ctx_t *current_conn = &head->connection;
-					return connection_handle_packet_prechecked(current_conn, &header, payload, payload_len);
+					result = connection_handle_packet_prechecked(current_conn, &header, payload, payload_len);
 				} else {
 					LOG(LVL_WARN, "Digipeater in CONN state, but there is no active connection! Packet dropped.");
-					return OK;
+					result = OK;
 				}
 			}
 
 		case DIGIPEATER_STATE_BEACON:
-			return digipeater_handle_beacon_responses(ctx, &header, payload, payload_len);
+			result = digipeater_handle_beacon_responses(ctx, &header, payload, payload_len);
 	}
 
-	return OK;
+	// end the current interval if tx_request is set in an incoming packet
+	if(header.tx_request) {
+		LOG(LVL_INFO, "TX Request was received. Ending current interval.");
+		digipeater_end_interval(ctx);
+	}
+
+	return result;
 }
 
 
@@ -188,24 +200,35 @@ size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t
 
 		ctx->state = DIGIPEATER_STATE_BEACON;
 		*end_burst = true;
-		return packet_size;
-	} else {
-		// pull packets from the current connection
-
-		connection_list_entry_t *head = connection_list_get_head(&ctx->conn_list);
-		if(!head) {
-			return 0;
-		}
-
-		connection_ctx_t *conn = &head->connection;
-		if(connection_can_transmit(conn)) {
-			packet_size = connection_encode_next_packet(conn, buf, buf_len, end_burst);
-
-			ctx->state = DIGIPEATER_STATE_CONN;
-		}
-
 		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) {
+		*end_burst = queue_entry->header.tx_request == 1;
+		packet_size = layer2_encode_packet(&queue_entry->header, queue_entry->data, queue_entry->data_len, buf, buf_len);
+		if(packet_size) {
+			packet_queue_delete(&ctx->oneshot_queue, 1);
+			return packet_size;
+		}
+	}
+
+	// pull packets from the current connection
+
+	connection_list_entry_t *head = connection_list_get_head(&ctx->conn_list);
+	if(!head) {
+		return 0;
+	}
+
+	connection_ctx_t *conn = &head->connection;
+	if(connection_can_transmit(conn)) {
+		packet_size = connection_encode_next_packet(conn, buf, buf_len, end_burst);
+
+		ctx->state = DIGIPEATER_STATE_CONN;
+	}
+
+	return packet_size;
 }
 
 
@@ -226,8 +249,37 @@ bool digipeater_can_transmit(digipeater_ctx_t *ctx)
 }
 
 
+void digipeater_extend_interval(digipeater_ctx_t *ctx, uint64_t ns)
+{
+	ctx->interval_end_time += ns;
+}
+
+
+result_t digipeater_end_interval(digipeater_ctx_t *ctx)
+{
+	uint64_t now = get_hires_time();
+
+	// 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;
+}
+
+
 result_t digipeater_maintain(digipeater_ctx_t *ctx)
 {
+	uint64_t now = get_hires_time();
+
+	if(now > ctx->interval_end_time) {
+		// at the end of the interval, the next connection is activated and the
+		// current one is re-scheduled.
+		LOG(LVL_DEBUG, "Interval ended by timeout at %llu ns.", now);
+	}
+
 	switch(ctx->state) {
 		case DIGIPEATER_STATE_CONN:
 			{

impl/src/layer2/digipeater.h

@@ -13,6 +13,7 @@
 #include <stdbool.h>
 
 #include "connection_list.h"
+#include "layer2/packet_queue.h"
 
 struct digipeater_ctx_s;
 
@@ -21,17 +22,28 @@ typedef enum {
 	DIGIPEATER_STATE_CONN,   //!< Handling client connections
 } digipeater_state_t;
 
+typedef enum {
+	DIGIPEATER_EVT_INTERVAL_END, //!< The current interval has ended and new packets should be transmitted.
+} digipeater_evt_t;
+
 /*!\brief Type for a callback function that is called when a data packet was received. */
-typedef void (*digipeater_data_callback_t)(struct digipeater_ctx_s *conn, const uint8_t *data, size_t len);
+typedef void (*digipeater_data_callback_t)(struct digipeater_ctx_s *digi, const uint8_t *data, size_t len);
+
+/*!\brief Type for a callback function that is called when certain events occur. */
+typedef void (*digipeater_evt_callback_t)(struct digipeater_ctx_s *digi, digipeater_evt_t evt);
 
 typedef struct digipeater_ctx_s {
 	digipeater_state_t state; //!< Current operating state
 
 	digipeater_data_callback_t data_cb; //!< Callback function for received data packets.
+	digipeater_evt_callback_t event_cb; //!< Callback function for events.
 
 	ham64_t my_addr;             //!< The local link layer address.
 
+	packet_queue_t oneshot_queue; //!< Queue for packets that are sent once and connection-independent
+
 	uint64_t next_beacon_time;   //!< Absolute timestamp of the next beacon transmission.
+	uint64_t interval_end_time;  //!< Absolute timestamp of the end of the current interval.
 
 	connection_list_t conn_list; //!< List of connections.
 } digipeater_ctx_t;
@@ -85,6 +97,26 @@ size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t
  */
 bool digipeater_can_transmit(digipeater_ctx_t *ctx);
 
+/*!\brief Extend the current interval.
+ *
+ * By default, the interval duration is set to a minimum length. It must be
+ * extended by the time needed to transmit and receive packets. As the time
+ * necessary for packet transfer is unknown to the Layer 2, it must be
+ * calculated externally.
+ *
+ * This function should be called whenever
+ * - A packet is transmitted from digipeater_encode_next_packet(), or
+ * - A packet is being received
+ */
+void digipeater_extend_interval(digipeater_ctx_t *ctx, uint64_t ns);
+
+/*!\brief End the current interval.
+ *
+ * End the interval without waiting for the timeout. This switches to the next
+ * connection and stop forwarding received packets to the current one.
+ */
+result_t digipeater_end_interval(digipeater_ctx_t *ctx);
+
 /*!\brief Handle internal maintenance tasks.
  *
  * This should be called periodically to handle timeouts and retransmissions.