From f25d7a882ad5d99540fb9da3fa8f0f84ea85d0bd Mon Sep 17 00:00:00 2001 From: Janez T Date: Wed, 18 Mar 2026 20:14:22 +0100 Subject: [PATCH] fix: Align channel data framing ref: #1928 --- docs/companion_protocol.md | 42 ++++++++++++----------------- examples/companion_radio/MyMesh.cpp | 33 +++++++++++------------ src/MeshCore.h | 2 +- src/Packet.h | 2 +- src/helpers/BaseChatMesh.cpp | 40 ++++++++++++++++++--------- 5 files changed, 63 insertions(+), 56 deletions(-) diff --git a/docs/companion_protocol.md b/docs/companion_protocol.md index c00be4a2..a8c09bef 100644 --- a/docs/companion_protocol.md +++ b/docs/companion_protocol.md @@ -303,7 +303,7 @@ Bytes 7+: Binary payload bytes (variable length) - Values other than `0xFF` are reserved for official protocol extensions. **Limits**: -- Maximum payload length is `163` bytes (`MAX_GROUP_DATA_LENGTH`). +- Maximum payload length is `160` bytes. - Larger payloads are rejected with `PACKET_ERROR` / `ERR_CODE_ILLEGAL_ARG`. **Response**: `PACKET_OK` (0x00) on success @@ -326,7 +326,7 @@ Byte 0: 0x0A **Response**: - `PACKET_CHANNEL_MSG_RECV` (0x08) or `PACKET_CHANNEL_MSG_RECV_V3` (0x11) for channel messages -- `PACKET_CHANNEL_DATA_RECV` (0x1B) or `PACKET_CHANNEL_DATA_RECV_V3` (0x1C) for channel data +- `PACKET_CHANNEL_DATA_RECV` (0x1B) for channel data - `PACKET_CONTACT_MSG_RECV` (0x07) or `PACKET_CONTACT_MSG_RECV_V3` (0x10) for contact messages - `PACKET_NO_MORE_MSGS` (0x0A) if no messages available @@ -397,8 +397,7 @@ Messages are received via the TX characteristic (notifications). The device send - `PACKET_CHANNEL_MSG_RECV_V3` (0x11) - Version 3 with SNR 2. **Channel Data**: - - `PACKET_CHANNEL_DATA_RECV` (0x1B) - Standard format - - `PACKET_CHANNEL_DATA_RECV_V3` (0x1C) - Version 3 with SNR + - `PACKET_CHANNEL_DATA_RECV` (0x1B) - Includes SNR and reserved bytes 3. **Contact Messages**: - `PACKET_CONTACT_MSG_RECV` (0x07) - Standard format @@ -502,26 +501,17 @@ Bytes 11+: Payload bytes ### Channel Data Format -**Standard Format** (`PACKET_CHANNEL_DATA_RECV`, 0x1B): +**Format** (`PACKET_CHANNEL_DATA_RECV`, 0x1B): ``` Byte 0: 0x1B (packet type) -Byte 1: Channel Index (0-7) -Byte 2: Path Length -Byte 3: Data Type -Bytes 4-7: Timestamp (32-bit little-endian) -Bytes 8+: Payload bytes -``` - -**V3 Format** (`PACKET_CHANNEL_DATA_RECV_V3`, 0x1C): -``` -Byte 0: 0x1C (packet type) Byte 1: SNR (signed byte, multiplied by 4) Bytes 2-3: Reserved Byte 4: Channel Index (0-7) Byte 5: Path Length Byte 6: Data Type -Bytes 7-10: Timestamp (32-bit little-endian) -Bytes 11+: Payload bytes +Byte 7: Data Length +Bytes 8-11: Timestamp (32-bit little-endian) +Bytes 12+: Payload bytes ``` **Parsing Pseudocode**: @@ -529,9 +519,10 @@ Bytes 11+: Payload bytes def parse_channel_frame(data): packet_type = data[0] offset = 1 + snr = None - # Check for V3 format - if packet_type in (0x11, 0x1C): # V3 + # Formats with explicit SNR/reserved bytes + if packet_type in (0x11, 0x1B): snr_byte = data[offset] snr = ((snr_byte if snr_byte < 128 else snr_byte - 256) / 4.0) offset += 3 # Skip SNR + reserved @@ -539,8 +530,10 @@ def parse_channel_frame(data): channel_idx = data[offset] path_len = data[offset + 1] item_type = data[offset + 2] - timestamp = int.from_bytes(data[offset+3:offset+7], 'little') - payload = data[offset+7:] + data_len = data[offset + 3] if packet_type == 0x1B else None + timestamp = int.from_bytes(data[offset+4:offset+8], 'little') if packet_type == 0x1B else int.from_bytes(data[offset+3:offset+7], 'little') + payload_offset = offset + 8 if packet_type == 0x1B else offset + 7 + payload = data[payload_offset:payload_offset + data_len] if packet_type == 0x1B else data[payload_offset:] is_text = packet_type in (0x08, 0x11) if is_text and item_type == 0: message = payload.decode('utf-8') @@ -553,7 +546,7 @@ def parse_channel_frame(data): 'timestamp': timestamp, 'payload': payload, 'message': message, - 'snr': snr if packet_type in (0x11, 0x1C) else None + 'snr': snr } ``` @@ -590,8 +583,7 @@ Use `CMD_SEND_CHANNEL_TXT_MSG` for plain text, and `CMD_SEND_CHANNEL_DATA` for b | 0x10 | PACKET_CONTACT_MSG_RECV_V3 | Contact message (V3 with SNR) | | 0x11 | PACKET_CHANNEL_MSG_RECV_V3 | Channel message (V3 with SNR) | | 0x12 | PACKET_CHANNEL_INFO | Channel information | -| 0x1B | PACKET_CHANNEL_DATA_RECV | Channel data (standard) | -| 0x1C | PACKET_CHANNEL_DATA_RECV_V3| Channel data (V3 with SNR) | +| 0x1B | PACKET_CHANNEL_DATA_RECV | Channel data (includes SNR) | | 0x80 | PACKET_ADVERTISEMENT | Advertisement packet | | 0x82 | PACKET_ACK | Acknowledgment | | 0x83 | PACKET_MESSAGES_WAITING | Messages waiting notification | @@ -892,7 +884,7 @@ def on_notification_received(data): packet_type = data[0] if packet_type in (PACKET_CHANNEL_MSG_RECV, PACKET_CHANNEL_MSG_RECV_V3, - PACKET_CHANNEL_DATA_RECV, PACKET_CHANNEL_DATA_RECV_V3): + PACKET_CHANNEL_DATA_RECV): message = parse_channel_frame(data) handle_channel_message(message) elif packet_type == PACKET_MESSAGES_WAITING: diff --git a/examples/companion_radio/MyMesh.cpp b/examples/companion_radio/MyMesh.cpp index 490f34a1..2a540c5b 100644 --- a/examples/companion_radio/MyMesh.cpp +++ b/examples/companion_radio/MyMesh.cpp @@ -93,7 +93,8 @@ #define RESP_CODE_AUTOADD_CONFIG 25 #define RESP_ALLOWED_REPEAT_FREQ 26 #define RESP_CODE_CHANNEL_DATA_RECV 27 -#define RESP_CODE_CHANNEL_DATA_RECV_V3 28 + +#define MAX_CHANNEL_DATA_LENGTH (MAX_FRAME_SIZE - 12) #define SEND_TIMEOUT_BASE_MILLIS 500 #define FLOOD_SEND_TIMEOUT_FACTOR 16.0f @@ -208,7 +209,7 @@ void MyMesh::updateContactFromFrame(ContactInfo &contact, uint32_t& last_mod, co bool MyMesh::Frame::isChannelMsg() const { return buf[0] == RESP_CODE_CHANNEL_MSG_RECV || buf[0] == RESP_CODE_CHANNEL_MSG_RECV_V3 || - buf[0] == RESP_CODE_CHANNEL_DATA_RECV || buf[0] == RESP_CODE_CHANNEL_DATA_RECV_V3; + buf[0] == RESP_CODE_CHANNEL_DATA_RECV; } void MyMesh::addToOfflineQueue(const uint8_t frame[], int len) { @@ -570,28 +571,26 @@ void MyMesh::onChannelMessageRecv(const mesh::GroupChannel &channel, mesh::Packe void MyMesh::onChannelDataRecv(const mesh::GroupChannel &channel, mesh::Packet *pkt, uint32_t timestamp, uint8_t data_type, const uint8_t *data, size_t data_len) { - int i = 0; - if (app_target_ver >= 3) { - out_frame[i++] = RESP_CODE_CHANNEL_DATA_RECV_V3; - out_frame[i++] = (int8_t)(pkt->getSNR() * 4); - out_frame[i++] = 0; // reserved1 - out_frame[i++] = 0; // reserved2 - } else { - out_frame[i++] = RESP_CODE_CHANNEL_DATA_RECV; + if (data_len > MAX_CHANNEL_DATA_LENGTH) { + MESH_DEBUG_PRINTLN("onChannelDataRecv: dropping payload_len=%d exceeds frame limit=%d", + (uint32_t)data_len, (uint32_t)MAX_CHANNEL_DATA_LENGTH); + return; } + int i = 0; + out_frame[i++] = RESP_CODE_CHANNEL_DATA_RECV; + out_frame[i++] = (int8_t)(pkt->getSNR() * 4); + out_frame[i++] = 0; // reserved1 + out_frame[i++] = 0; // reserved2 + uint8_t channel_idx = findChannelIdx(channel); out_frame[i++] = channel_idx; out_frame[i++] = pkt->isRouteFlood() ? pkt->path_len : 0xFF; out_frame[i++] = data_type; + out_frame[i++] = (uint8_t)data_len; memcpy(&out_frame[i], ×tamp, 4); i += 4; - size_t available = MAX_FRAME_SIZE - i; - if (data_len > available) { - MESH_DEBUG_PRINTLN("onChannelDataRecv(): payload_len=%d exceeds frame space=%d, truncating", (uint32_t)data_len, (uint32_t)available); - data_len = available; - } int copy_len = (int)data_len; if (copy_len > 0) { memcpy(&out_frame[i], data, copy_len); @@ -1108,8 +1107,8 @@ void MyMesh::handleCmdFrame(size_t len) { writeErrFrame(ERR_CODE_NOT_FOUND); // bad channel_idx } else if (data_type != DATA_TYPE_CUSTOM) { writeErrFrame(ERR_CODE_UNSUPPORTED_CMD); - } else if (payload_len > MAX_GROUP_DATA_LENGTH) { - MESH_DEBUG_PRINTLN("CMD_SEND_CHANNEL_DATA payload too long: %d > %d", payload_len, MAX_GROUP_DATA_LENGTH); + } else if (payload_len > MAX_CHANNEL_DATA_LENGTH) { + MESH_DEBUG_PRINTLN("CMD_SEND_CHANNEL_DATA payload too long: %d > %d", payload_len, MAX_CHANNEL_DATA_LENGTH); writeErrFrame(ERR_CODE_ILLEGAL_ARG); } else if (sendGroupData(msg_timestamp, channel.channel, data_type, payload, payload_len)) { writeOKFrame(); diff --git a/src/MeshCore.h b/src/MeshCore.h index 3eb4f935..cf8f949e 100644 --- a/src/MeshCore.h +++ b/src/MeshCore.h @@ -17,7 +17,7 @@ #define PATH_HASH_SIZE 1 #define MAX_PACKET_PAYLOAD 184 -#define MAX_GROUP_DATA_LENGTH (MAX_PACKET_PAYLOAD - CIPHER_BLOCK_SIZE - 5) +#define MAX_GROUP_DATA_LENGTH (MAX_PACKET_PAYLOAD - CIPHER_BLOCK_SIZE - 6) #define MAX_PATH_SIZE 64 #define MAX_TRANS_UNIT 255 diff --git a/src/Packet.h b/src/Packet.h index 78619546..c5c5ab00 100644 --- a/src/Packet.h +++ b/src/Packet.h @@ -22,7 +22,7 @@ namespace mesh { #define PAYLOAD_TYPE_ACK 0x03 // a simple ack #define PAYLOAD_TYPE_ADVERT 0x04 // a node advertising its Identity #define PAYLOAD_TYPE_GRP_TXT 0x05 // an (unverified) group text message (prefixed with channel hash, MAC) (enc data: timestamp, "name: msg") -#define PAYLOAD_TYPE_GRP_DATA 0x06 // an (unverified) group datagram (prefixed with channel hash, MAC) (enc data: timestamp, blob) +#define PAYLOAD_TYPE_GRP_DATA 0x06 // an (unverified) group datagram (prefixed with channel hash, MAC) (enc data: timestamp, data_type, data_len, blob) #define PAYLOAD_TYPE_ANON_REQ 0x07 // generic request (prefixed with dest_hash, ephemeral pub_key, MAC) (enc data: ...) #define PAYLOAD_TYPE_PATH 0x08 // returned path (prefixed with dest/src hashes, MAC) (enc data: path, extra) #define PAYLOAD_TYPE_TRACE 0x09 // trace a path, collecting SNI for each hop diff --git a/src/helpers/BaseChatMesh.cpp b/src/helpers/BaseChatMesh.cpp index d8e089d5..5f4e0d4d 100644 --- a/src/helpers/BaseChatMesh.cpp +++ b/src/helpers/BaseChatMesh.cpp @@ -353,15 +353,15 @@ int BaseChatMesh::searchChannelsByHash(const uint8_t* hash, mesh::GroupChannel d #endif void BaseChatMesh::onGroupDataRecv(mesh::Packet* packet, uint8_t type, const mesh::GroupChannel& channel, uint8_t* data, size_t len) { - if (len < 5) { - MESH_DEBUG_PRINTLN("onGroupDataRecv: dropping short group payload len=%d", (uint32_t)len); - return; - } - - uint8_t data_type = data[4]; if (type == PAYLOAD_TYPE_GRP_TXT) { - if ((data_type >> 2) != 0) { - MESH_DEBUG_PRINTLN("onGroupDataRecv: dropping unsupported group text type=%d", (uint32_t)data_type); + if (len < 5) { + MESH_DEBUG_PRINTLN("onGroupDataRecv: dropping short group text payload len=%d", (uint32_t)len); + return; + } + + uint8_t txt_type = data[4]; + if ((txt_type >> 2) != 0) { + MESH_DEBUG_PRINTLN("onGroupDataRecv: dropping unsupported group text type=%d", (uint32_t)txt_type); return; } @@ -374,9 +374,24 @@ void BaseChatMesh::onGroupDataRecv(mesh::Packet* packet, uint8_t type, const mes // notify UI of this new message onChannelMessageRecv(channel, packet, timestamp, (const char *) &data[5]); // let UI know } else if (type == PAYLOAD_TYPE_GRP_DATA) { + if (len < 6) { + MESH_DEBUG_PRINTLN("onGroupDataRecv: dropping short group data payload len=%d", (uint32_t)len); + return; + } + uint32_t timestamp; memcpy(×tamp, data, 4); - onChannelDataRecv(channel, packet, timestamp, data_type, &data[5], len - 5); + uint8_t data_type = data[4]; + uint8_t data_len = data[5]; + size_t available_len = len - 6; + + if (data_len > available_len) { + MESH_DEBUG_PRINTLN("onGroupDataRecv: dropping malformed group data type=%d len=%d available=%d", + (uint32_t)data_type, (uint32_t)data_len, (uint32_t)available_len); + return; + } + + onChannelDataRecv(channel, packet, timestamp, data_type, &data[6], data_len); } } @@ -478,12 +493,13 @@ bool BaseChatMesh::sendGroupData(uint32_t timestamp, mesh::GroupChannel& channel return false; } - uint8_t temp[5 + MAX_GROUP_DATA_LENGTH]; + uint8_t temp[6 + MAX_GROUP_DATA_LENGTH]; memcpy(temp, ×tamp, 4); temp[4] = data_type; - if (data_len > 0) memcpy(&temp[5], data, data_len); + temp[5] = (uint8_t)data_len; + if (data_len > 0) memcpy(&temp[6], data, data_len); - auto pkt = createGroupDatagram(PAYLOAD_TYPE_GRP_DATA, channel, temp, 5 + data_len); + auto pkt = createGroupDatagram(PAYLOAD_TYPE_GRP_DATA, channel, temp, 6 + data_len); if (pkt == NULL) { MESH_DEBUG_PRINTLN("sendGroupData: unable to create group datagram, data_len=%d", data_len); return false;