M3 step 4: the LoRa Scanner App, Sniffer and Captures

The Sniffer lists packets newest first (time, RSSI, SNR, and for
Meshtastic the sender, receiver and hops), with the clear header and a
hex dump on Enter (Q96); `p` picks an EU868 preset, kept in Settings
(Q95). `c` starts a Capture: pcap with LoRaTap in /captures/lora, its own
Clean-up category, recorded by a small Service so it carries on with the
App closed (Q97, Q100). The Status Bar shows L while listening, bright on
each packet, and CAP while capturing (Q101). StorageService gains raw
appends for binary files. Debug Builds get `lora inject` to test all of
this with no transmitter in range: a Capture made on the device reads
back in TShark field for field.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/services/radio_service.cpp

@@ -108,6 +108,7 @@ void RadioService::run() {
 void RadioService::startListening() {
     if (!ring_) {
         ring_.reset(new (std::nothrow) RadioPacket[kRing]);
+        ringFirst_ = seq_ + 1;
         if (!ring_) {
             console.println("radio: not enough memory to listen");
             clients_ = 0;
@@ -169,14 +170,33 @@ void RadioService::readPacket() {
     if (receive() != RADIOLIB_ERR_NONE) ++radioErrors_;
     ++restarts_;
 
+    store(p);
+}
+
+void RadioService::store(RadioPacket& p) {
     xSemaphoreTake(lock_, portMAX_DELAY);
     p.seq = seq_ + 1;
     if (ring_) ring_[p.seq % kRing] = p;
     seq_ = p.seq;
     xSemaphoreGive(lock_);
     ++packets_;
+    lastPacketMs_ = p.ms;
 }
 
+#ifdef RORO_DEBUG
+void RadioService::inject(const uint8_t* data, size_t len, float rssi, float snr) {
+    if (!listening_) return (void)console.println("lora inject: not listening");
+    RadioPacket p;
+    Config c = config();
+    p.ms = millis();
+    p.len = static_cast<uint8_t>(std::min(len, sizeof p.data));
+    std::copy(data, data + p.len, p.data);
+    p.rx = {c.frequencyHz, c.bandwidthKHz, c.spreadingFactor, rssi, snr, noise_, c.syncWord};
+    store(p);
+    console.printf("lora inject: #%lu, %u B\n", (unsigned long)p.seq, p.len);
+}
+#endif
+
 // Continuous receive. Only RX done raises DIO1; preambles and headers are only recorded in the
 // IRQ status, which sampleNoise() reads.
 int16_t RadioService::receive() {
@@ -206,6 +226,12 @@ bool RadioService::packet(uint32_t seq, RadioPacket& out) const {
     return ok;
 }
 
+uint32_t RadioService::available() const {
+    uint32_t newest = seq_, first = ringFirst_;
+    if (!listening_ || newest < first) return 0;
+    return std::min<uint32_t>(newest - first + 1, kRing);
+}
+
 void RadioService::listen(Client client, bool on) {
     if (on) clients_ |= client;
     else clients_ &= ~client;