WIP: Add adaptive advert flood rate limiter

docs/cli_commands.md

@@ -440,6 +440,18 @@ This document provides an overview of CLI commands that can be sent to MeshCore
 
 ---
 
+#### View or change the advert rate limiter (Repeater Only)
+**Usage:**
+- `get advert.ratelimit`
+- `set advert.ratelimit <state>`
+
+**Parameters:**
+- `state`: `on`|`off`
+
+**Default:** `on`
+
+---
+
 #### View or change this node's advert path hash size
 **Usage:**
 - `get path.hash.mode`

examples/simple_repeater/MyMesh.cpp

@@ -428,6 +428,9 @@ void MyMesh::sendFloodReply(mesh::Packet* packet, unsigned long delay_millis, ui
 
 bool MyMesh::allowPacketForward(const mesh::Packet *packet) {
   if (_prefs.disable_fwd) return false;
+  if (!_prefs.disable_advert_rate_limiter
+      && packet->getPayloadType() == PAYLOAD_TYPE_ADVERT
+      && !advert_limiter.allow(rtc_clock.getCurrentTime())) return false;
   if (packet->isRouteFlood() && packet->getPathHashCount() >= _prefs.flood_max) return false;
   if (packet->isRouteFlood() && recv_pkt_region == NULL) {
     MESH_DEBUG_PRINTLN("allowPacketForward: unknown transport code, or wildcard not allowed for FLOOD packet");
@@ -848,7 +851,8 @@ MyMesh::MyMesh(mesh::MainBoard &board, mesh::Radio &radio, mesh::MillisecondCloc
       _cli(board, rtc, sensors, region_map, acl, &_prefs, this),
       telemetry(MAX_PACKET_PAYLOAD - 4),
       discover_limiter(4, 120),  // max 4 every 2 minutes
-      anon_limiter(4, 180)   // max 4 every 3 minutes
+      anon_limiter(4, 180),  // max 4 every 3 minutes
+      advert_limiter(300, 3, 5)  // 5-min window, 3x burst, floor 5
 #if defined(WITH_RS232_BRIDGE)
       , bridge(&_prefs, WITH_RS232_BRIDGE, _mgr, &rtc)
 #endif

examples/simple_repeater/MyMesh.h

@@ -99,6 +99,7 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   RegionEntry* recv_pkt_region;
   TransportKey default_scope;
   RateLimiter discover_limiter, anon_limiter;
+  AdaptiveRateLimiter advert_limiter;
   uint32_t pending_discover_tag;
   unsigned long pending_discover_until;
   bool region_load_active;

examples/simple_repeater/RateLimiter.h

@@ -3,21 +3,100 @@
 #include <stdint.h>
 
 class RateLimiter {
-  uint32_t _start_timestamp;
-  uint32_t _secs;
-  uint16_t _maximum, _count;
+  uint32_t _start;
+  uint16_t _secs;
+  uint16_t _maximum;
+  uint16_t _count;
 
 public:
-  RateLimiter(uint16_t maximum, uint32_t secs): _maximum(maximum), _secs(secs), _start_timestamp(0), _count(0) { }
+  RateLimiter(uint16_t maximum, uint16_t secs)
+      : _start(0), _secs(secs), _maximum(maximum), _count(0) {}
 
   bool allow(uint32_t now) {
-    if (now < _start_timestamp + _secs) {
-      _count++;
-      if (_count > _maximum) return false;   // deny
-    } else {   // time window now expired
-      _start_timestamp = now;
-      _count = 1;
+    if (now - _start >= _secs) {
+      _start = now;
+      _count = 0;
     }
+
+    if (_count >= _maximum)
+      return false;
+
+    _count++;
+
+    return true;
+  }
+};
+
+class AdaptiveRateLimiter {
+  enum {
+    EWMA_SMOOTHING = 3,
+    EWMA_TOTAL_WEIGHT = EWMA_SMOOTHING + 1,
+    EWMA_GROWTH_CAP = 4
+  };
+
+  static_assert(EWMA_SMOOTHING >= 1 && EWMA_SMOOTHING <= 256, "EWMA_SMOOTHING must be 1-256");
+  static_assert(EWMA_GROWTH_CAP >= 1, "EWMA_GROWTH_CAP must be at least 1");
+
+  uint32_t _start;
+  uint16_t _secs;
+  uint8_t _count;
+  uint8_t _limit;
+  uint8_t _ewma;
+  uint8_t _burst;
+  uint8_t _floor;
+
+  static uint8_t clampU8(uint16_t v) { return v > 255 ? 255 : (uint8_t)v; }
+
+  uint8_t nextEwma() const {
+    uint8_t cap = clampU8((uint16_t)_ewma + EWMA_GROWTH_CAP);
+    uint8_t effective = (_count > _ewma) ? cap : _count;
+    uint16_t next = (uint16_t)_ewma * EWMA_SMOOTHING + effective;
+
+    return (uint8_t)(next / EWMA_TOTAL_WEIGHT);
+  }
+
+  uint8_t computeLimit() const {
+    uint8_t clamped = clampU8((uint16_t)_ewma * _burst);
+    return clamped > _floor ? clamped : _floor;
+  }
+
+  void advanceWindow(uint32_t now) {
+    if (now - _start < _secs)
+      return;
+
+    uint32_t elapsed = (_secs == 0) ? 1 : (now - _start) / _secs;
+
+    if (elapsed > EWMA_TOTAL_WEIGHT * 8)
+      elapsed = EWMA_TOTAL_WEIGHT * 8;
+
+    _ewma = nextEwma();
+    _limit = computeLimit();
+
+    while (elapsed > 1 && _ewma > 0) {
+      _count = 0;
+      _ewma = nextEwma();
+      _limit = computeLimit();
+
+      elapsed--;
+    }
+
+    _start = now;
+    _count = 0;
+  }
+
+public:
+  AdaptiveRateLimiter(uint16_t secs, uint8_t burst, uint8_t floor)
+      : _start(0), _secs(secs), _count(0), _limit(floor), _ewma(floor),
+        _burst(burst), _floor(floor) {}
+
+  bool allow(uint32_t now) {
+    advanceWindow(now);
+
+    if (_count >= _limit)
+      return false;
+
+    _count++;
+
     return true;
   }
-};
+};

src/helpers/CommonCLI.cpp

@@ -89,7 +89,8 @@ void CommonCLI::loadPrefsInt(FILESYSTEM* fs, const char* filename) {
     file.read((uint8_t *)&_prefs->adc_multiplier, sizeof(_prefs->adc_multiplier));                 // 166
     file.read((uint8_t *)_prefs->owner_info, sizeof(_prefs->owner_info));                          // 170
     file.read((uint8_t *)&_prefs->rx_boosted_gain, sizeof(_prefs->rx_boosted_gain));              // 290
-    // next: 291
+    file.read((uint8_t *)&_prefs->disable_advert_rate_limiter, sizeof(_prefs->disable_advert_rate_limiter));   // 291
+    // next: 292
 
     // sanitise bad pref values
     _prefs->rx_delay_base = constrain(_prefs->rx_delay_base, 0, 20.0f);
@@ -180,7 +181,8 @@ void CommonCLI::savePrefs(FILESYSTEM* fs) {
     file.write((uint8_t *)&_prefs->adc_multiplier, sizeof(_prefs->adc_multiplier));                 // 166
     file.write((uint8_t *)_prefs->owner_info, sizeof(_prefs->owner_info));                          // 170
     file.write((uint8_t *)&_prefs->rx_boosted_gain, sizeof(_prefs->rx_boosted_gain));              // 290
-    // next: 291
+    file.write((uint8_t *)&_prefs->disable_advert_rate_limiter, sizeof(_prefs->disable_advert_rate_limiter)); // 291
+    // next: 292
 
     file.close();
   }
@@ -547,6 +549,10 @@ void CommonCLI::handleSetCmd(uint32_t sender_timestamp, char* command, char* rep
     _prefs->disable_fwd = memcmp(&config[7], "off", 3) == 0;
     savePrefs();
     strcpy(reply, _prefs->disable_fwd ? "OK - repeat is now OFF" : "OK - repeat is now ON");
+  } else if (memcmp(config, "advert.ratelimit ", 17) == 0) {
+    _prefs->disable_advert_rate_limiter = memcmp(&config[17], "off", 3) == 0;
+    savePrefs();
+    strcpy(reply, _prefs->disable_advert_rate_limiter ? "OK - advert rate limiter OFF" : "OK - advert rate limiter ON");
 #if defined(USE_SX1262) || defined(USE_SX1268)
   } else if (memcmp(config, "radio.rxgain ", 13) == 0) {
     _prefs->rx_boosted_gain = memcmp(&config[13], "on", 2) == 0;
@@ -765,6 +771,8 @@ void CommonCLI::handleGetCmd(uint32_t sender_timestamp, char* command, char* rep
     sprintf(reply, "> %s", _prefs->node_name);
   } else if (memcmp(config, "repeat", 6) == 0) {
     sprintf(reply, "> %s", _prefs->disable_fwd ? "off" : "on");
+  } else if (memcmp(config, "advert.ratelimit", 16) == 0) {
+    sprintf(reply, "> %s", _prefs->disable_advert_rate_limiter ? "off" : "on");
   } else if (memcmp(config, "lat", 3) == 0) {
     sprintf(reply, "> %s", StrHelper::ftoa(_prefs->node_lat));
   } else if (memcmp(config, "lon", 3) == 0) {

src/helpers/CommonCLI.h

@@ -61,6 +61,7 @@ struct NodePrefs { // persisted to file
   uint8_t rx_boosted_gain; // power settings
   uint8_t path_hash_mode;   // which path mode to use when sending
   uint8_t loop_detect;
+  uint8_t disable_advert_rate_limiter;
 };
 
 class CommonCLICallbacks {