WIP: digipeater module managing multiple connections
Backup commit. This is a basic setup with lots of TODOs and errors. Will not compile yet.
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122
impl/src/layer2/digipeater.c
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122
impl/src/layer2/digipeater.c
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#include <string.h>
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#include <assert.h>
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#include "digipeater.h"
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#include "config.h"
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#include "layer2/connection.h"
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#include "layer2/ham64.h"
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#include "results.h"
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#include "utils.h"
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result_t digipeater_init(digipeater_ctx_t *ctx, const ham64_t *my_addr, digipeater_data_callback_t data_cb)
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{
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ctx->my_addr = *my_addr;
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ctx->data_cb = data_cb;
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ctx->state = DIGIPEATER_STATE_CONN;
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uint64_t now = get_hires_time();
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ctx->next_beacon_time = now + HRTIME_MS(BEACON_INTERVAL_MS);
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return connection_list_init(&ctx->conn_list);
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}
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void digipeater_destroy(digipeater_ctx_t *ctx)
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{
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connection_list_destroy(&ctx->conn_list);
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}
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result_t digipeater_handle_packet(digipeater_ctx_t *ctx, const uint8_t *buf, size_t buf_len)
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{
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// check the CRC
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size_t packet_size = buf_len - crc_sizeof_key(PAYLOAD_CRC_SCHEME);
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if(!crc_check_key(PAYLOAD_CRC_SCHEME, (unsigned char*)buf, packet_size)) {
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LOG(LVL_ERR, "CRC check failed!");
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return ERR_INTEGRITY;
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}
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// decode the header
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layer2_packet_header_t header;
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if(!layer2_decode_packet_header(buf, buf_len, &header)) {
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LOG(LVL_ERR, "Header could not be decoded!");
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return ERR_INTEGRITY;
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}
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layer2_dump_packet_header(LVL_DUMP, &header);
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// check if the packet really should be handled by us
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if(ham64_is_equal(&ctx->my_addr, &header.src_addr)) {
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LOG(LVL_DEBUG, "Packet is from ourselves. Ignored.");
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return OK;
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}
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if(!ham64_is_equal(&header.dst_addr, &ctx->my_addr)) {
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char fmt_dst_addr[HAM64_FMT_MAX_LEN];
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char fmt_my_addr[HAM64_FMT_MAX_LEN];
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ham64_format(&header.dst_addr, fmt_dst_addr);
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ham64_format(&ctx->my_addr, fmt_my_addr);
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LOG(LVL_ERR, "Packet has the wrong destination address: got %s, expected %s",
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fmt_dst_addr, fmt_my_addr);
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return ERR_INVALID_ADDRESS;
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}
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// FIXME: handle connection management packets here
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// FIXME: handle data and empty packets in the current connection
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size_t header_size = layer2_get_encoded_header_size(&header);
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const uint8_t *payload = buf + header_size;
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size_t payload_len = packet_size - header_size;
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connection_handle_packet_prechecked(current_conn, &header, payload, payload_len);
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return OK;
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}
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size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t buf_len, bool *end_burst)
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{
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uint64_t now = get_hires_time();
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*end_burst = false;
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if(now > ctx->next_beacon_time) {
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// TODO: build a beacon packet
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return 0;
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}
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// TODO: pull packets from the current connection
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return 0;
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}
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bool digipeater_can_transmit(const digipeater_ctx_t *ctx)
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{
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uint64_t now = get_hires_time();
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if(now > ctx->next_beacon_time) {
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return true;
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}
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// TODO: also true if next TX time has expired and there are packets waiting for this connection.
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/*return (packet_queue_get_used_space(&ctx->packet_queue) != 0)
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&& (packet_queue_get(&ctx->packet_queue, ctx->next_packet_index) != NULL); */
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return false;
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}
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result_t digipeater_maintain(digipeater_ctx_t *ctx)
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{
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(void)ctx;
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return OK;
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}
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94
impl/src/layer2/digipeater.h
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impl/src/layer2/digipeater.h
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/*
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* This file contains functions to handle a single layer 2 digipeater.
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*
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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* Copyright (C) 2024 Thomas Kolb
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*/
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#ifndef DIGIPEATER_H
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#define DIGIPEATER_H
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#include <results.h>
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#include <stdbool.h>
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#include "connection_list.h"
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struct digipeater_ctx_s;
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typedef enum {
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DIGIPEATER_STATE_BEACON, //!< Beacon sent, waiting for connection requests
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DIGIPEATER_STATE_CONN, //!< Handling client connections
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} digipeater_state_t;
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/*!\brief Type for a callback function that is called when a data packet was received. */
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typedef void (*digipeater_data_callback_t)(struct digipeater_ctx_s *conn, const uint8_t *data, size_t len);
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typedef struct digipeater_ctx_s {
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digipeater_state_t state; //!< Current operating state
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digipeater_data_callback_t data_cb; //!< Callback function for received data packets.
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ham64_t my_addr; //!< The local link layer address.
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uint64_t next_beacon_time; //!< Absolute timestamp of the next beacon transmission.
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connection_list_t conn_list; //!< List of connections.
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} digipeater_ctx_t;
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/*!\brief Initialize the digipeater context.
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*
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* \param ctx The digipeater context to initialize.
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* \param my_addr The local link layer address.
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* \param data_cb Callback function that handles received (decoded) data packets.
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* \returns OK if everything worked or a fitting error code.
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*/
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result_t digipeater_init(
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digipeater_ctx_t *ctx,
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const ham64_t *my_addr,
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digipeater_data_callback_t data_cb);
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/*!\brief Destroy the given digipeater context.
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*/
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void digipeater_destroy(digipeater_ctx_t *ctx);
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/*!\brief Handle a received packet.
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*
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* \param ctx The digipeater context.
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* \param buf Pointer to the packet data.
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* \param buf_len Length of the packet.
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* \returns A result code from the packet handling procedure.
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*/
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result_t digipeater_handle_packet(digipeater_ctx_t *ctx, const uint8_t *buf, size_t buf_len);
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/*!\brief Enqueue a packet for transmission.
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* \param ctx The digipeater context.
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* \param tun_fd File descriptor for an open TUN device.
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*/
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result_t digipeater_fill_packet_queues_from_tundev(digipeater_ctx_t *ctx, int tun_fd);
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/*!\brief Encode the next packet for transmission.
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*
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* \note
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* If no packets are currently available for transmission, this function returns zero.
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*
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* \param ctx The digipeater context.
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* \param buf Where to write the encoded packet data.
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* \param buf_len Space available in the buffer.
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* \param end_burst Set to true if this packet should end the current burst and start the transmission.
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* \returns The number of bytes written to buf or zero if no packet was available.
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*/
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size_t digipeater_encode_next_packet(digipeater_ctx_t *ctx, uint8_t *buf, size_t buf_len, bool *end_burst);
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/*!\brief Check if there are packets queued for transmission.
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*/
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bool digipeater_can_transmit(const digipeater_ctx_t *ctx);
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/*!\brief Handle internal maintenance tasks.
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*
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* This should be called periodically to handle timeouts and retransmissions.
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*/
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result_t digipeater_maintain(digipeater_ctx_t *ctx);
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#endif // DIGIPEATER_H
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