fix beacon: add onAdvertRecv to display received beacons

src/main.cpp

@@ -305,6 +305,20 @@ public:
             NVIC_SystemReset();
         }
     }
+
+    void onAdvertRecv(mesh::Packet* pkt, const mesh::Identity& id, uint32_t ts, const uint8_t* app_data, size_t app_data_len) override {
+        char buf[128];
+        int n = 0;
+        n += snprintf(buf + n, sizeof(buf) - n, "beacon:");
+        if (app_data_len > 0 && app_data[0]) {
+            int l = app_data_len; if (l > 20) l = 20;
+            memcpy(buf + n, app_data, l); n += l;
+        } else {
+            for (int i = 0; i < 4 && i < (int)PUB_KEY_SIZE; i++) { n += snprintf(buf + n, sizeof(buf) - n, "%02X", id.pub_key[i]); }
+        }
+        buf[n] = 0;
+        send_text(buf);
+    }
 };
 
 SecurityMesh the_mesh(radio_driver, fast_rng, rtc_clock, tables);