client: Change wire format!: Add epoch

[tattlekey] / client / net.c

/* tattlekey: A one-key UDP keyboard
 * Copyright (C) 2023  Scott Worley <scottworley@scottworley.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "net.h"
#include "blink.h"
#include "config.h"

#include "pico/cyw43_arch.h"
#include "pico/rand.h"

#include "lwip/pbuf.h"
#include "lwip/udp.h"

/* We only ever send to one address, and we only ever have one thread, so just
 * use one udp_pcb */
static struct udp_pcb *the_pcb = NULL;
static uint32_t epoch = 0;

static void net_local_init() {
  if (the_pcb)
    return;

  epoch = get_rand_32();

  the_pcb = udp_new();
  if (!the_pcb)
    signal_error_by_blinking();

  ip_addr_t ipaddr;
  if (ip4addr_aton(config_tattle_server_ip_address, &ipaddr) == 0)
    signal_error_by_blinking();

  if (udp_connect(the_pcb, &ipaddr, config_tattle_port) != ERR_OK)
    signal_error_by_blinking();
}

struct tattle_message_wire_format {
  u32_t epoch;
  u16_t sender;
  u16_t seq;
  u32_t ago;
};

void send_report_packet(u16_t seq, u32_t ago) {
  cyw43_arch_lwip_begin();

  net_local_init();

  struct pbuf *p = pbuf_alloc(
      PBUF_TRANSPORT, sizeof(struct tattle_message_wire_format), PBUF_RAM);
  if (!p)
    signal_error_by_blinking();

  struct tattle_message_wire_format *msg =
      (struct tattle_message_wire_format *)(p->payload);
  msg->epoch = htonl(epoch);
  msg->sender = htons(config_this_tattler_identity);
  msg->seq = htons(seq);
  msg->ago = htonl(ago);

  if (udp_send(the_pcb, p) != ERR_OK)
    signal_error_by_blinking();

  pbuf_free(p);

  cyw43_arch_lwip_end();
}