Fix sending out broadcast messages

Broadcast peer must be added to the peer list before being able to use it.

main/Kconfig.projbuild

@@ -0,0 +1,23 @@
+menu "EspTunnel Configuration"
+
+    config ESPTNL_PMK
+        string "ESPNOW primary master key"
+        default "pmk1234567890123"
+        help
+            ESPNOW primary master key. Must be 16 bytes.
+
+    config ESPTNL_LMK
+        string "ESPNOW local master key"
+        default "lmk1234567890123"
+        help
+            ESPNOW local master key. Must be 16 bytes.
+
+
+    config ESPTNL_CHANNEL
+        int "Channel"
+        default 1
+        range 0 14
+        help
+            The channel for sending and receiving ESPNOW data.
+
+endmenu

main/app_networking.cpp

@@ -10,6 +10,7 @@
 #include "esp_now.h"
 #include "esp_wifi.h"
 #include "esp_log.h"
+#include "esp_wifi.h"
 
 namespace
 {
@@ -21,10 +22,18 @@ static const char* TAG = "Networking";
 static_assert(std::is_standard_layout_v<EspNowEvent> && std::is_trivial_v<EspNowEvent>,
         "EspNowEvent is not compatible with a FreeRTOS queue.");
 
+template<std::size_t N>
+constexpr auto STR_LEN(const char (&s)[N])
+{
+  return N;
+}
+
+static_assert(STR_LEN(CONFIG_ESPTNL_PMK) == ESP_NOW_KEY_LEN + 1, "CONFIG_ESPTNL_PMK must be of length 16 bytes + 1 null terminator.");
+static_assert(STR_LEN(CONFIG_ESPTNL_LMK) == ESP_NOW_KEY_LEN + 1, "CONFIG_ESPTNL_LMK must be of length 16 bytes + 1 null terminator.");
+
 QueueHandle_t s_esp_now_queue = nullptr;
 std::array<std::uint8_t, 128> s_rx_buffer;
 std::variant<MacAddress, std::monostate> s_peer;
-bool s_tx_inflight = false;
 
 bool s_isBroadcastAddress(const std::uint8_t* mac)
 {
@@ -37,13 +46,28 @@ bool s_isBroadcastAddress(const esp_now_recv_info_t* sender)
   return s_isBroadcastAddress(sender->src_addr);
 }
 
+bool s_addPeer(const MacAddress& peer_address)
+{
+  esp_now_peer_info_t broadcast_peer;
+  std::memset(&broadcast_peer, 0, sizeof(broadcast_peer));
+
+  broadcast_peer.channel = CONFIG_ESPTNL_CHANNEL;
+  broadcast_peer.ifidx = WIFI_IF_STA;
+  broadcast_peer.encrypt = false;
+  std::memcpy(broadcast_peer.lmk, CONFIG_ESPTNL_LMK, ESP_NOW_KEY_LEN);
+  std::memcpy(broadcast_peer.peer_addr, peer_address.data(), peer_address.size());
+
+  auto successful = esp_now_add_peer(&broadcast_peer);
+  ESP_ERROR_CHECK_WITHOUT_ABORT(successful);
+
+  return successful == ESP_OK;
+}
+
 void s_cbEspNowSendComplete(const std::uint8_t* peer_mac, esp_now_send_status_t status)
 {
-  s_tx_inflight = false;
-
   EspNowEvent event = { EspNowEvent::MSG_SEND_COMPLETE, 0 };
   xQueueSend(s_esp_now_queue, &event, 0);
-  ESP_LOGD(TAG, "Send complete. s_tx_inflight = false.");
+  ESP_LOGD(TAG, "Send complete.");
 }
 
 void s_cbEspNowReceiveComplete(const esp_now_recv_info_t* recv_info, const std::uint8_t* data, int len)
@@ -72,7 +96,7 @@ void setupWifi()
   ESP_ERROR_CHECK(esp_wifi_set_storage(WIFI_STORAGE_RAM));
   ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
   ESP_ERROR_CHECK(esp_wifi_start());
-  ESP_ERROR_CHECK(esp_wifi_set_channel(1, WIFI_SECOND_CHAN_NONE));
+  ESP_ERROR_CHECK(esp_wifi_set_channel(CONFIG_ESPTNL_CHANNEL, WIFI_SECOND_CHAN_NONE));
 }
 
 QueueHandle_t setupEspNow()
@@ -81,12 +105,15 @@ QueueHandle_t setupEspNow()
   ESP_ERROR_CHECK(s_esp_now_queue == nullptr);
 
   ESP_ERROR_CHECK(esp_now_init());
-  //    ESP_ERROR_CHECK(esp_now_set_pmk(nullptr));
+  ESP_ERROR_CHECK(esp_now_set_pmk((const std::uint8_t*)CONFIG_ESPTNL_PMK));
 
   ESP_ERROR_CHECK(esp_now_register_send_cb(s_cbEspNowSendComplete));
   ESP_ERROR_CHECK(esp_now_register_recv_cb(s_cbEspNowReceiveComplete));
 
-  s_peer = MacAddress{ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
+  const auto broadcast_mac = MacAddress{ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
+  s_peer = broadcast_mac;
+
+  ESP_ERROR_CHECK(s_addPeer(broadcast_mac));
 
   return s_esp_now_queue;
 }
@@ -99,13 +126,11 @@ const std::array<std::uint8_t, 128>& getRxBuffer()
 void sendData(const std::array<std::uint8_t, 128>& buffer, const std::size_t length)
 {
   if (const MacAddress* peer_mac = std::get_if<MacAddress>(&s_peer);
-      !s_tx_inflight && peer_mac != nullptr)
+      peer_mac != nullptr)
   {
-    esp_now_send(peer_mac->data(), buffer.data(), length);
-    if (!s_isBroadcastAddress(peer_mac->data()))
-      s_tx_inflight = true;
+    ESP_ERROR_CHECK_WITHOUT_ABORT(esp_now_send(peer_mac->data(), buffer.data(), length));
 
-    ESP_LOGD(TAG, "Message send started. s_tx_inflight = %d.", s_tx_inflight);
+    ESP_LOGD(TAG, "Message send started.");
   }
   else
   {