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* Mesh::onAnonDataRecv() slight optimisation, so that shared-secret calc doesn't need to be repeated

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* SensporMesh: req_type now optionally encoded in anon_req payload (so can send various requests without a prior login)
This commit is contained in:
Scott Powell
2025-07-07 20:41:28 +10:00
parent 7fb7b69bbc
commit 810b1f8fe7
6 changed files with 76 additions and 60 deletions
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111
examples/simple_sensor/SensorMesh.cpp
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@@ -46,6 +46,7 @@
/* ------------------------------ Code -------------------------------- */
#define REQ_TYPE_LOGIN 0x00
#define REQ_TYPE_GET_STATUS 0x01
#define REQ_TYPE_KEEP_ALIVE 0x02
#define REQ_TYPE_GET_TELEMETRY_DATA 0x03
@@ -139,12 +140,10 @@ void SensorMesh::saveContacts() {
}
}
int SensorMesh::handleRequest(ContactInfo& sender, uint32_t sender_timestamp, uint8_t* payload, size_t payload_len) {
// uint32_t now = getRTCClock()->getCurrentTimeUnique();
// memcpy(reply_data, &now, 4); // response packets always prefixed with timestamp
uint8_t SensorMesh::handleRequest(bool is_admin, uint32_t sender_timestamp, uint8_t req_type, uint8_t* payload, size_t payload_len) {
memcpy(reply_data, &sender_timestamp, 4); // reflect sender_timestamp back in response packet (kind of like a 'tag')
switch (payload[0]) {
switch (req_type) {
case REQ_TYPE_GET_TELEMETRY_DATA: {
telemetry.reset();
telemetry.addVoltage(TELEM_CHANNEL_SELF, (float)board.getBattMilliVolts() / 1000.0f);
@@ -253,63 +252,79 @@ int SensorMesh::getAGCResetInterval() const {
return ((int)_prefs.agc_reset_interval) * 4000; // milliseconds
}
void SensorMesh::onAnonDataRecv(mesh::Packet* packet, uint8_t type, const mesh::Identity& sender, uint8_t* data, size_t len) {
if (type == PAYLOAD_TYPE_ANON_REQ) { // received an initial request by a possible admin client (unknown at this stage)
uint8_t SensorMesh::handleLoginReq(const mesh::Identity& sender, const uint8_t* secret, uint32_t sender_timestamp, const uint8_t* data) {
bool is_admin;
if (strcmp((char *) data, _prefs.password) == 0) { // check for valid password
is_admin = true;
} else if (strcmp((char *) data, _prefs.guest_password) == 0) { // check guest password
is_admin = false;
} else {
#if MESH_DEBUG
MESH_DEBUG_PRINTLN("Invalid password: %s", &data[4]);
#endif
return 0;
}
auto client = putContact(sender); // add to contacts (if not already known)
if (sender_timestamp <= client->last_timestamp) {
MESH_DEBUG_PRINTLN("Possible login replay attack!");
return 0; // FATAL: client table is full -OR- replay attack
}
MESH_DEBUG_PRINTLN("Login success!");
client->last_timestamp = sender_timestamp;
client->last_activity = getRTCClock()->getCurrentTime();
client->type = is_admin ? 1 : 0;
memcpy(client->shared_secret, secret, PUB_KEY_SIZE);
if (is_admin) {
// only need to saveContacts() if this is an admin
dirty_contacts_expiry = futureMillis(LAZY_CONTACTS_WRITE_DELAY);
}
uint32_t now = getRTCClock()->getCurrentTimeUnique();
memcpy(reply_data, &now, 4); // response packets always prefixed with timestamp
reply_data[4] = RESP_SERVER_LOGIN_OK;
reply_data[5] = 0; // NEW: recommended keep-alive interval (secs / 16)
reply_data[6] = client->type;
reply_data[7] = 0; // FUTURE: reserved
getRNG()->random(&reply_data[8], 4); // random blob to help packet-hash uniqueness
return 12; // reply length
}
void SensorMesh::onAnonDataRecv(mesh::Packet* packet, const uint8_t* secret, const mesh::Identity& sender, uint8_t* data, size_t len) {
if (packet->getPayloadType() == PAYLOAD_TYPE_ANON_REQ) { // received an initial request by a possible admin client (unknown at this stage)
uint32_t timestamp;
memcpy(&timestamp, data, 4);
bool is_admin;
data[len] = 0; // ensure null terminator
if (strcmp((char *) &data[4], _prefs.password) == 0) { // check for valid password
is_admin = true;
} else if (strcmp((char *) &data[4], _prefs.guest_password) == 0) { // check guest password
is_admin = false;
uint8_t req_code;
uint8_t i = 4;
if (data[4] < 32) { // non-print char, is a request code
req_code = data[i++];
} else {
#if MESH_DEBUG
MESH_DEBUG_PRINTLN("Invalid password: %s", &data[4]);
#endif
return;
req_code = REQ_TYPE_LOGIN;
}
auto client = putContact(sender); // add to contacts (if not already known)
if (timestamp <= client->last_timestamp) {
MESH_DEBUG_PRINTLN("Possible login replay attack!");
return; // FATAL: client table is full -OR- replay attack
uint8_t reply_len;
if (req_code == REQ_TYPE_LOGIN) {
reply_len = handleLoginReq(sender, secret, timestamp, &data[i]);
} else {
reply_len = handleRequest(false, timestamp, req_code, &data[i], len - i);
}
MESH_DEBUG_PRINTLN("Login success!");
client->last_timestamp = timestamp;
client->last_activity = getRTCClock()->getCurrentTime();
client->type = is_admin ? 1 : 0;
self_id.calcSharedSecret(client->shared_secret, client->id); // calc ECDH shared secret
if (is_admin) {
// only need to saveContacts() if this is an admin
dirty_contacts_expiry = futureMillis(LAZY_CONTACTS_WRITE_DELAY);
}
uint32_t now = getRTCClock()->getCurrentTimeUnique();
memcpy(reply_data, &now, 4); // response packets always prefixed with timestamp
reply_data[4] = RESP_SERVER_LOGIN_OK;
reply_data[5] = 0; // NEW: recommended keep-alive interval (secs / 16)
reply_data[6] = client->type;
reply_data[7] = 0; // FUTURE: reserved
getRNG()->random(&reply_data[8], 4); // random blob to help packet-hash uniqueness
if (reply_len == 0) return; // invalid request
if (packet->isRouteFlood()) {
// let this sender know path TO here, so they can use sendDirect(), and ALSO encode the response
mesh::Packet* path = createPathReturn(sender, client->shared_secret, packet->path, packet->path_len,
PAYLOAD_TYPE_RESPONSE, reply_data, 12);
mesh::Packet* path = createPathReturn(sender, secret, packet->path, packet->path_len,
PAYLOAD_TYPE_RESPONSE, reply_data, reply_len);
if (path) sendFlood(path, SERVER_RESPONSE_DELAY);
} else {
mesh::Packet* reply = createDatagram(PAYLOAD_TYPE_RESPONSE, sender, client->shared_secret, reply_data, 12);
if (reply) {
if (client->out_path_len >= 0) { // we have an out_path, so send DIRECT
sendDirect(reply, client->out_path, client->out_path_len, SERVER_RESPONSE_DELAY);
} else {
sendFlood(reply, SERVER_RESPONSE_DELAY);
}
}
mesh::Packet* reply = createDatagram(PAYLOAD_TYPE_RESPONSE, sender, secret, reply_data, reply_len);
if (reply) sendFlood(reply, SERVER_RESPONSE_DELAY);
}
}
}
@@ -361,7 +376,7 @@ void SensorMesh::onPeerDataRecv(mesh::Packet* packet, uint8_t type, int sender_i
memcpy(&timestamp, data, 4);
if (timestamp > from.last_timestamp) { // prevent replay attacks
int reply_len = handleRequest(from, timestamp, &data[4], len - 4);
uint8_t reply_len = handleRequest(from.isAdmin(), timestamp, data[4], &data[5], len - 5);
if (reply_len == 0) return; // invalid command
from.last_timestamp = timestamp;