feat(mesh): add BLE advertisement mesh bearer scaffold

Author: Komzpa

src/configuration.h

@@ -423,6 +423,25 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifndef HAS_BLUETOOTH
 #define HAS_BLUETOOTH 0
 #endif
+#ifndef HAS_BLE_MESH_ADVERTISING
+// Keep the experimental BLE advertisement bearer opt-in by platform capability:
+// it currently needs a NimBLE2 build with a spare legacy advertising instance.
+// Bluefruit/nRF52 builds compile the shared codec but leave the bearer disabled
+// until there is a backend that can scan and advertise without disturbing the
+// normal phone GATT advertising path.
+#if HAS_BLUETOOTH && defined(ARCH_ESP32) && defined(NIMBLE_TWO) && defined(CONFIG_BT_NIMBLE_EXT_ADV) &&                             \
+    CONFIG_BT_NIMBLE_EXT_ADV && defined(CONFIG_BT_NIMBLE_MAX_EXT_ADV_INSTANCES) && CONFIG_BT_NIMBLE_MAX_EXT_ADV_INSTANCES > 1
+#define HAS_BLE_MESH_ADVERTISING 1
+#else
+#define HAS_BLE_MESH_ADVERTISING 0
+#endif
+#endif
+#ifndef BLE_MESH_ADVERTISEMENT_COMPANY_ID
+// Experimental company id used by the BLE advertisement mesh bearer.  Builds
+// can override this once Meshtastic chooses a final Bluetooth SIG/company-data
+// allocation or switches the bearer to service data.
+#define BLE_MESH_ADVERTISEMENT_COMPANY_ID 0x05e1
+#endif
 #ifndef USE_TFTDISPLAY
 #define USE_TFTDISPLAY 0
 #endif

src/mesh/Router.cpp

@@ -14,6 +14,9 @@
 #if !MESHTASTIC_EXCLUDE_MQTT
 #include "mqtt/MQTT.h"
 #endif
+#if HAS_BLE_MESH_ADVERTISING
+#include "mesh/ble/BleAdvertisementMesh.h"
+#endif
 #include "Default.h"
 #if ARCH_PORTDUINO
 #include "Throttle.h"
@@ -381,6 +384,13 @@ ErrorCode Router::send(meshtastic_MeshPacket *p)
     }
 #endif
 
+#if HAS_BLE_MESH_ADVERTISING
+    if (bleAdvertisementMesh &&
+        config.network.enabled_protocols & meshtastic_Config_NetworkConfig_ProtocolFlags_BLE_ADVERTISEMENT_BROADCAST) {
+        bleAdvertisementMesh->onSend(p);
+    }
+#endif
+
     assert(iface); // This should have been detected already in sendLocal (or we just received a packet from outside)
     return iface->send(p);
 }

src/mesh/ble/BleAdvertisementMesh.cpp

@@ -0,0 +1,309 @@
+#include "configuration.h"
+#include "mesh/ble/BleAdvertisementMesh.h"
+#include "mesh/mesh-pb-constants.h"
+
+#if HAS_BLE_MESH_ADVERTISING
+#include "Router.h"
+#include "main.h"
+#endif
+#include <pb_decode.h>
+#include <pb_encode.h>
+#include <string.h>
+
+namespace
+{
+uint16_t crc16ccitt(const uint8_t *data, size_t length)
+{
+    uint16_t crc = 0xffff;
+    for (size_t i = 0; i < length; i++) {
+        crc ^= static_cast<uint16_t>(data[i]) << 8;
+        for (uint8_t bit = 0; bit < 8; bit++) {
+            crc = (crc & 0x8000) ? static_cast<uint16_t>((crc << 1) ^ 0x1021) : static_cast<uint16_t>(crc << 1);
+        }
+    }
+    return crc;
+}
+
+void putLe16(uint8_t *p, uint16_t v)
+{
+    p[0] = static_cast<uint8_t>(v);
+    p[1] = static_cast<uint8_t>(v >> 8);
+}
+
+void putLe32(uint8_t *p, uint32_t v)
+{
+    p[0] = static_cast<uint8_t>(v);
+    p[1] = static_cast<uint8_t>(v >> 8);
+    p[2] = static_cast<uint8_t>(v >> 16);
+    p[3] = static_cast<uint8_t>(v >> 24);
+}
+
+uint16_t getLe16(const uint8_t *p)
+{
+    return static_cast<uint16_t>(p[0]) | (static_cast<uint16_t>(p[1]) << 8);
+}
+
+uint32_t getLe32(const uint8_t *p)
+{
+    return static_cast<uint32_t>(p[0]) | (static_cast<uint32_t>(p[1]) << 8) | (static_cast<uint32_t>(p[2]) << 16) |
+           (static_cast<uint32_t>(p[3]) << 24);
+}
+} // namespace
+
+BleAdvertisementMeshCodec::BleAdvertisementMeshCodec() {}
+
+uint8_t BleAdvertisementMeshCodec::frameCount(const meshtastic_MeshPacket *mp)
+{
+    if (!mp || mp->which_payload_variant != meshtastic_MeshPacket_encrypted_tag) {
+        return 0;
+    }
+
+    uint8_t encoded[meshtastic_MeshPacket_size] = {0};
+    size_t encodedLength = pb_encode_to_bytes(encoded, sizeof(encoded), &meshtastic_MeshPacket_msg, mp);
+    if (encodedLength == 0) {
+        return 0;
+    }
+
+    return (encodedLength + MAX_FRAGMENT_PAYLOAD_SIZE - 1) / MAX_FRAGMENT_PAYLOAD_SIZE;
+}
+
+bool BleAdvertisementMeshCodec::forEachFrame(const meshtastic_MeshPacket *mp, EmitFrame emit, void *context)
+{
+    if (!mp || !emit || mp->which_payload_variant != meshtastic_MeshPacket_encrypted_tag) {
+        return false;
+    }
+
+    uint8_t encoded[meshtastic_MeshPacket_size] = {0};
+    size_t encodedLength = pb_encode_to_bytes(encoded, sizeof(encoded), &meshtastic_MeshPacket_msg, mp);
+    if (encodedLength == 0) {
+        return false;
+    }
+
+    uint8_t fragmentCount = (encodedLength + MAX_FRAGMENT_PAYLOAD_SIZE - 1) / MAX_FRAGMENT_PAYLOAD_SIZE;
+    if (fragmentCount == 0 || fragmentCount > MAX_FRAGMENTS) {
+        return false;
+    }
+
+    uint16_t crc = crc16ccitt(encoded, encodedLength);
+    for (uint8_t fragment = 0; fragment < fragmentCount; fragment++) {
+        size_t offset = fragment * MAX_FRAGMENT_PAYLOAD_SIZE;
+        size_t remaining = encodedLength - offset;
+        uint8_t payloadLength =
+            static_cast<uint8_t>(remaining > MAX_FRAGMENT_PAYLOAD_SIZE ? MAX_FRAGMENT_PAYLOAD_SIZE : remaining);
+
+        uint8_t frame[MAX_FRAME_SIZE] = {0};
+        frame[0] = FRAME_MAGIC_0;
+        frame[1] = FRAME_MAGIC_1;
+        frame[2] = FRAME_VERSION;
+        frame[3] = fragment;
+        frame[4] = fragmentCount;
+        frame[5] = payloadLength;
+        putLe32(&frame[6], mp->from);
+        putLe32(&frame[10], mp->id);
+        putLe16(&frame[14], crc);
+        memcpy(&frame[FRAME_HEADER_SIZE], &encoded[offset], payloadLength);
+
+        if (!emit(frame, FRAME_HEADER_SIZE + payloadLength, context)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+void BleAdvertisementMeshCodec::reset(uint32_t from, uint32_t packetId, uint16_t crc, uint8_t fragmentCount)
+{
+    currentFrom = from;
+    currentPacketId = packetId;
+    currentCrc = crc;
+    expectedFragments = fragmentCount;
+    lastFragmentLength = 0;
+    receivedMask = 0;
+    memset(encodedPacket, 0, sizeof(encodedPacket));
+}
+
+bool BleAdvertisementMeshCodec::receiveFrame(const uint8_t *frame, size_t frameLength, meshtastic_MeshPacket *out)
+{
+    if (!frame || !out || frameLength < FRAME_HEADER_SIZE || frameLength > MAX_FRAME_SIZE || frame[0] != FRAME_MAGIC_0 ||
+        frame[1] != FRAME_MAGIC_1 || frame[2] != FRAME_VERSION) {
+        return false;
+    }
+
+    uint8_t fragment = frame[3];
+    uint8_t fragmentCount = frame[4];
+    uint8_t payloadLength = frame[5];
+    uint32_t from = getLe32(&frame[6]);
+    uint32_t packetId = getLe32(&frame[10]);
+    uint16_t crc = getLe16(&frame[14]);
+
+    if (fragmentCount == 0 || fragmentCount > MAX_FRAGMENTS || fragment >= fragmentCount ||
+        payloadLength > MAX_FRAGMENT_PAYLOAD_SIZE || frameLength != FRAME_HEADER_SIZE + payloadLength) {
+        return false;
+    }
+
+    size_t offset = fragment * MAX_FRAGMENT_PAYLOAD_SIZE;
+    if (offset + payloadLength > sizeof(encodedPacket)) {
+        return false;
+    }
+
+    if (from != currentFrom || packetId != currentPacketId || crc != currentCrc || fragmentCount != expectedFragments) {
+        reset(from, packetId, crc, fragmentCount);
+    }
+
+    memcpy(&encodedPacket[offset], &frame[FRAME_HEADER_SIZE], payloadLength);
+    receivedMask |= 1ULL << fragment;
+    if (fragment == fragmentCount - 1) {
+        lastFragmentLength = payloadLength;
+    }
+
+    uint64_t completeMask = fragmentCount == 64 ? UINT64_MAX : ((1ULL << fragmentCount) - 1);
+    if (receivedMask != completeMask || lastFragmentLength == 0) {
+        return false;
+    }
+
+    size_t encodedLength = (fragmentCount - 1) * MAX_FRAGMENT_PAYLOAD_SIZE + lastFragmentLength;
+    if (crc16ccitt(encodedPacket, encodedLength) != currentCrc) {
+        reset(0, 0, 0, 0);
+        return false;
+    }
+
+    memset(out, 0, sizeof(*out));
+    bool decoded = pb_decode_from_bytes(encodedPacket, encodedLength, &meshtastic_MeshPacket_msg, out);
+    reset(0, 0, 0, 0);
+    return decoded;
+}
+
+#if HAS_BLE_MESH_ADVERTISING
+
+BleAdvertisementMesh *bleAdvertisementMesh = nullptr;
+
+namespace
+{
+struct PlatformEmitContext
+{
+    BleAdvertisementMesh::QueuedFrame *frames;
+    uint8_t maxFrames;
+    uint8_t count;
+};
+
+bool emitPlatformFrame(const uint8_t *frame, size_t frameLength, void *context)
+{
+    auto *platformContext = static_cast<PlatformEmitContext *>(context);
+    if (!platformContext || !frame || frameLength == 0 || frameLength > BleAdvertisementMeshCodec::MAX_FRAME_SIZE ||
+        platformContext->count >= platformContext->maxFrames) {
+        return false;
+    }
+
+    BleAdvertisementMesh::QueuedFrame &queued = platformContext->frames[platformContext->count++];
+    memcpy(queued.data, frame, frameLength);
+    queued.length = frameLength;
+    return true;
+}
+} // namespace
+
+BleAdvertisementMesh::BleAdvertisementMesh(PlatformAdvertiseFrame advertiseFrame)
+    : concurrency::OSThread("BleAdvMesh"), advertiseFrame(advertiseFrame)
+{
+}
+
+bool BleAdvertisementMesh::onSend(const meshtastic_MeshPacket *mp)
+{
+    if (!mp || !advertiseFrame ||
+        mp->transport_mechanism == meshtastic_MeshPacket_TransportMechanism_TRANSPORT_BLE_ADVERTISEMENT) {
+        return false;
+    }
+
+    uint8_t neededFrames = BleAdvertisementMeshCodec::frameCount(mp);
+    uint16_t queuedCopies = static_cast<uint16_t>(neededFrames) * FRAME_REPEAT_ROUNDS;
+    if (neededFrames == 0 || queuedCopies > freeSlots()) {
+        LOG_WARN("Drop BLE advertisement broadcast id=%u, fragments=%u free=%u", mp->id, neededFrames, freeSlots());
+        return false;
+    }
+
+    QueuedFrame frames[BleAdvertisementMeshCodec::MAX_FRAGMENTS];
+    PlatformEmitContext context = {frames, BleAdvertisementMeshCodec::MAX_FRAGMENTS, 0};
+    if (!BleAdvertisementMeshCodec::forEachFrame(mp, emitPlatformFrame, &context) || context.count != neededFrames) {
+        return false;
+    }
+
+    LOG_DEBUG("Queue packet for BLE advertisements (id=%u fragments=%u rounds=%u)", mp->id, neededFrames, FRAME_REPEAT_ROUNDS);
+    for (uint8_t round = 0; round < FRAME_REPEAT_ROUNDS; round++) {
+        for (uint8_t i = 0; i < context.count; i++) {
+            const QueuedFrame &frame = context.frames[(round + i) % context.count];
+            if (!enqueueFrame(frame.data, frame.length)) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+void BleAdvertisementMesh::onAdvertisement(const uint8_t *frame, size_t frameLength)
+{
+    meshtastic_MeshPacket mp = {};
+    if (!codec.receiveFrame(frame, frameLength, &mp)) {
+        return;
+    }
+
+    if (!rememberPacket(mp.from, mp.id)) {
+        LOG_DEBUG("Drop duplicate BLE advertisement packet (from=0x%x id=%u)", mp.from, mp.id);
+        return;
+    }
+
+    if (router && mp.which_payload_variant == meshtastic_MeshPacket_encrypted_tag) {
+        mp.transport_mechanism = meshtastic_MeshPacket_TransportMechanism_TRANSPORT_BLE_ADVERTISEMENT;
+        UniquePacketPoolPacket p = packetPool.allocUniqueCopy(mp);
+        p->rx_snr = 0;
+        p->rx_rssi = 0;
+        router->enqueueReceivedMessage(p.release());
+    }
+}
+
+bool BleAdvertisementMesh::enqueueFrame(const uint8_t *frame, size_t frameLength)
+{
+    if (!frame || frameLength == 0 || frameLength > BleAdvertisementMeshCodec::MAX_FRAME_SIZE || queuedFrames >= FRAME_QUEUE_SIZE) {
+        return false;
+    }
+
+    QueuedFrame &queued = queue[queueTail];
+    memcpy(queued.data, frame, frameLength);
+    queued.length = frameLength;
+    queueTail = (queueTail + 1) % FRAME_QUEUE_SIZE;
+    queuedFrames++;
+    setIntervalFromNow(0);
+    return true;
+}
+
+bool BleAdvertisementMesh::rememberPacket(uint32_t from, uint32_t packetId)
+{
+    for (uint8_t i = 0; i < RECENT_PACKET_COUNT; i++) {
+        if (recentFrom[i] == from && recentPacketId[i] == packetId) {
+            return false;
+        }
+    }
+
+    recentFrom[recentPacketIndex] = from;
+    recentPacketId[recentPacketIndex] = packetId;
+    recentPacketIndex = (recentPacketIndex + 1) % RECENT_PACKET_COUNT;
+    return true;
+}
+
+int32_t BleAdvertisementMesh::runOnce()
+{
+    if (!advertiseFrame || queuedFrames == 0) {
+        return 1000;
+    }
+
+    QueuedFrame queued = queue[queueHead];
+    queueHead = (queueHead + 1) % FRAME_QUEUE_SIZE;
+    queuedFrames--;
+
+    if (!advertiseFrame(queued.data, queued.length)) {
+        LOG_WARN("BLE advertisement frame transmit failed");
+    }
+
+    return queuedFrames > 0 ? FRAME_INTERVAL_MS : 1000;
+}
+
+#endif // HAS_BLE_MESH_ADVERTISING