Guard channel content filter behind WITH_CHANNEL_FILTER

Feature is now fully compiled out unless built with -D WITH_CHANNEL_FILTER.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

docs/cli_commands.md

@@ -118,6 +118,8 @@ This document provides an overview of CLI commands that can be sent to MeshCore
 
 ## Channel Content Filter (Repeater Only)
 
+> **Compile-time feature.** These commands only exist when the firmware is built with `-D WITH_CHANNEL_FILTER`. Without that build flag the feature is fully compiled out (no code, no storage, no CLI commands) and the repeater behaves exactly as stock.
+
 Lets a repeater decrypt channels it holds the key for, inspect the plaintext, and refuse to retransmit messages that match a blocked keyword or sender name. With nothing configured, behaviour is identical to a stock repeater.
 
 **How it works:** the repeater only decrypts channels you explicitly load a key for (see `filter channel`). For those channels it reads the sender name and message text; any message matching a blocked keyword (text, case-insensitive substring) or blocked sender (case-insensitive substring of the sender name) is dropped instead of forwarded. All other channels — and direct messages — are never decrypted and forward exactly as before.
@@ -131,7 +133,7 @@ Lets a repeater decrypt channels it holds the key for, inspect the plaintext, an
 
 **Config storage:** persisted to `/channel_filter` on the node's filesystem.
 
-**Build flags:** `MAX_FILTER_CHANNELS` (default `4`), `MAX_FILTER_TERMS` (default `8`, applies to keywords and senders independently).
+**Build flags:** `WITH_CHANNEL_FILTER` (required, enables the feature), `MAX_FILTER_CHANNELS` (default `4`), `MAX_FILTER_TERMS` (default `8`, applies to keywords and senders independently).
 
 ---
 

examples/simple_repeater/MyMesh.cpp

@@ -1,8 +1,10 @@
 #include "MyMesh.h"
-#include "UnicodeFold.h"
 #include <algorithm>
 #include <ctype.h>
 
+#ifdef WITH_CHANNEL_FILTER
+#include "UnicodeFold.h"
+
 /* --------------------- public-channel content filter ------------------ */
 
 // The well-known MeshCore public channel PSK ("izOH6cXN6mrJ5e26oRXNcg==")
@@ -35,6 +37,7 @@ static int decodeBase64(const char* in, uint8_t* out, int max_out) {
   }
   return n;
 }
+#endif  // WITH_CHANNEL_FILTER
 
 
 /* ------------------------------ Config -------------------------------- */
@@ -663,6 +666,7 @@ void MyMesh::getPeerSharedSecret(uint8_t *dest_secret, int peer_idx) {
   }
 }
 
+#ifdef WITH_CHANNEL_FILTER
 bool MyMesh::addFilterChannel(const char *psk_b64) {
   if (num_filter_channels >= MAX_FILTER_CHANNELS) return false;
 
@@ -865,6 +869,7 @@ void MyMesh::handleFilterCommand(char *command, char *reply) {
   }
   strcpy(reply, "Err - usage: filter [list|stats [reset]|channel <b64|public|clear>|block <kw>|sender <name>|clear|reset]");
 }
+#endif  // WITH_CHANNEL_FILTER
 
 static bool isShare(const mesh::Packet *packet) {
   if (packet->hasTransportCodes()) {
@@ -1101,10 +1106,12 @@ MyMesh::MyMesh(mesh::MainBoard &board, mesh::Radio &radio, mesh::MillisecondCloc
 {
   last_millis = 0;
   uptime_millis = 0;
+#ifdef WITH_CHANNEL_FILTER
   num_filter_channels = 0;
   num_block_keywords = 0;
   num_block_senders = 0;
   n_filtered = 0;
+#endif
   next_local_advert = next_flood_advert = 0;
   dirty_contacts_expiry = 0;
   set_radio_at = revert_radio_at = 0;
@@ -1173,7 +1180,9 @@ void MyMesh::begin(FILESYSTEM *fs) {
   // load persisted prefs
   _cli.loadPrefs(_fs);
   acl.load(_fs, self_id);
+#ifdef WITH_CHANNEL_FILTER
   loadChannelFilter();
+#endif
   // TODO: key_store.begin();
   region_map.load(_fs);
 
@@ -1501,8 +1510,10 @@ void MyMesh::handleCommand(uint32_t sender_timestamp, char *command, char *reply
       sendNodeDiscoverReq();
       strcpy(reply, "OK - Discover sent");
     }
+#ifdef WITH_CHANNEL_FILTER
   } else if (memcmp(command, "filter", 6) == 0 && (command[6] == 0 || command[6] == ' ')) {
     handleFilterCommand(command, reply);
+#endif
   } else{
     _cli.handleCommand(sender_timestamp, command, reply);  // common CLI commands
   }

examples/simple_repeater/MyMesh.h

@@ -79,6 +79,8 @@ struct NeighbourInfo {
 #define FIRMWARE_ROLE "repeater"
 
 #define PACKET_LOG_FILE  "/packet_log"
+
+#ifdef WITH_CHANNEL_FILTER
 #define CHANNEL_FILTER_FILE  "/channel_filter"
 
 #ifndef MAX_FILTER_CHANNELS
@@ -89,6 +91,7 @@ struct NeighbourInfo {
 #endif
 #define FILTER_TERM_LEN     24
 #define FILTER_PSK_B64_LEN  48
+#endif
 
 class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   FILESYSTEM* _fs;
@@ -124,6 +127,7 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   uint8_t pending_cr;
   int  matching_peer_indexes[MAX_CLIENTS];
 
+#ifdef WITH_CHANNEL_FILTER
   mesh::GroupChannel filter_channels[MAX_FILTER_CHANNELS];
   char filter_channel_psk[MAX_FILTER_CHANNELS][FILTER_PSK_B64_LEN];
   uint8_t num_filter_channels;
@@ -132,6 +136,7 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   char block_senders[MAX_FILTER_TERMS][FILTER_TERM_LEN];
   uint8_t num_block_senders;
   uint32_t n_filtered;
+#endif
 #if defined(WITH_RS232_BRIDGE)
   RS232Bridge bridge;
 #elif defined(WITH_ESPNOW_BRIDGE)
@@ -149,10 +154,12 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   File openAppend(const char* fname);
   bool isLooped(const mesh::Packet* packet, const uint8_t max_counters[]);
 
+#ifdef WITH_CHANNEL_FILTER
   bool addFilterChannel(const char* psk_b64);
   void loadChannelFilter();
   void saveChannelFilter();
   void handleFilterCommand(char* command, char* reply);
+#endif
 
 protected:
   float getAirtimeBudgetFactor() const override {
@@ -191,8 +198,10 @@ protected:
 
   void onAnonDataRecv(mesh::Packet* packet, const uint8_t* secret, const mesh::Identity& sender, uint8_t* data, size_t len) override;
   int searchPeersByHash(const uint8_t* hash) override;
+#ifdef WITH_CHANNEL_FILTER
   int searchChannelsByHash(const uint8_t* hash, mesh::GroupChannel channels[], int max_matches) override;
   void onGroupDataRecv(mesh::Packet* packet, uint8_t type, const mesh::GroupChannel& channel, uint8_t* data, size_t len) override;
+#endif
   void getPeerSharedSecret(uint8_t* dest_secret, int peer_idx) override;
   void onAdvertRecv(mesh::Packet* packet, const mesh::Identity& id, uint32_t timestamp, const uint8_t* app_data, size_t app_data_len);
   void onPeerDataRecv(mesh::Packet* packet, uint8_t type, int sender_idx, const uint8_t* secret, uint8_t* data, size_t len) override;