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MeshCore/examples/simple_secure_chat/main.cpp
T
João Brázio 95214e8c40 Ensure command buffers stay NUL-terminated to prevent overflow 
The serial command buffers must stay NUL-terminated within their
bounds: if they ever aren't, strlen() can return >= sizeof(command)
and the read loop would index past the buffer. Additionally, a full
buffer now becomes a completed line (end-of-line marker placed
inside the buffer, NUL terminator kept) instead of overwriting the
terminator and silently corrupting the buffer for the next pass.

Applies to the serial CLI readers of the repeater, room server,
sensor and secure chat examples, and to the CLI rescue reader of
the companion example.
2026-09-04 20:01:39 +01:00

614 lines
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#include <Arduino.h> // needed for PlatformIO
#include <Mesh.h>
#if defined(NRF52_PLATFORM)
#include <InternalFileSystem.h>
#elif defined(RP2040_PLATFORM)
#include <LittleFS.h>
#elif defined(ESP32)
#include <SPIFFS.h>
#endif
#include <helpers/ArduinoHelpers.h>
#include <helpers/StaticPoolPacketManager.h>
#include <helpers/SimpleMeshTables.h>
#include <helpers/IdentityStore.h>
#include <RTClib.h>
#include <target.h>
/* ---------------------------------- CONFIGURATION ------------------------------------- */
#define FIRMWARE_VER_TEXT "v2 (build: 4 Feb 2025)"
#ifndef LORA_FREQ
#define LORA_FREQ 915.0
#endif
#ifndef LORA_BW
#define LORA_BW 250
#endif
#ifndef LORA_SF
#define LORA_SF 10
#endif
#ifndef LORA_CR
#define LORA_CR 5
#endif
#ifndef LORA_TX_POWER
#define LORA_TX_POWER 20
#endif
#ifndef MAX_CONTACTS
#define MAX_CONTACTS 100
#endif
#include <helpers/BaseChatMesh.h>
#define SEND_TIMEOUT_BASE_MILLIS 500
#define FLOOD_SEND_TIMEOUT_FACTOR 16.0f
#define DIRECT_SEND_PERHOP_FACTOR 6.0f
#define DIRECT_SEND_PERHOP_EXTRA_MILLIS 250
#define PUBLIC_GROUP_PSK "izOH6cXN6mrJ5e26oRXNcg=="
// Believe it or not, this std C function is busted on some platforms!
static uint32_t _atoi(const char* sp) {
uint32_t n = 0;
while (*sp && *sp >= '0' && *sp <= '9') {
n *= 10;
n += (*sp++ - '0');
}
return n;
}
/* -------------------------------------------------------------------------------------- */
struct NodePrefs { // persisted to file
float airtime_factor;
char node_name[32];
double node_lat, node_lon;
float freq;
int8_t tx_power_dbm;
uint8_t unused[3];
};
class MyMesh : public BaseChatMesh, ContactVisitor {
FILESYSTEM* _fs;
NodePrefs _prefs;
uint32_t expected_ack_crc;
ChannelDetails* _public;
unsigned long last_msg_sent;
ContactInfo* curr_recipient;
char command[512+10];
uint8_t tmp_buf[256];
char hex_buf[512];
const char* getTypeName(uint8_t type) const {
if (type == ADV_TYPE_CHAT) return "Chat";
if (type == ADV_TYPE_REPEATER) return "Repeater";
if (type == ADV_TYPE_ROOM) return "Room";
return "??"; // unknown
}
void loadContacts() {
if (_fs->exists("/contacts")) {
#if defined(RP2040_PLATFORM)
File file = _fs->open("/contacts", "r");
#else
File file = _fs->open("/contacts");
#endif
if (file) {
bool full = false;
while (!full) {
ContactInfo c;
uint8_t pub_key[32];
uint8_t unused;
uint32_t reserved;
bool success = (file.read(pub_key, 32) == 32);
success = success && (file.read((uint8_t *) &c.name, 32) == 32);
success = success && (file.read(&c.type, 1) == 1);
success = success && (file.read(&c.flags, 1) == 1);
success = success && (file.read(&unused, 1) == 1);
success = success && (file.read((uint8_t *) &reserved, 4) == 4);
success = success && (file.read((uint8_t *) &c.out_path_len, 1) == 1);
success = success && (file.read((uint8_t *) &c.last_advert_timestamp, 4) == 4);
success = success && (file.read(c.out_path, 64) == 64);
c.gps_lat = c.gps_lon = 0; // not yet supported
if (!success) break; // EOF
c.id = mesh::Identity(pub_key);
c.lastmod = 0;
if (!addContact(c)) full = true;
}
file.close();
}
}
}
void saveContacts() {
#if defined(NRF52_PLATFORM)
_fs->remove("/contacts");
File file = _fs->open("/contacts", FILE_O_WRITE);
#elif defined(RP2040_PLATFORM)
File file = _fs->open("/contacts", "w");
#else
File file = _fs->open("/contacts", "w", true);
#endif
if (file) {
ContactsIterator iter = startContactsIterator();
ContactInfo c;
uint8_t unused = 0;
uint32_t reserved = 0;
while (iter.hasNext(this, c)) {
bool success = (file.write(c.id.pub_key, 32) == 32);
success = success && (file.write((uint8_t *) &c.name, 32) == 32);
success = success && (file.write(&c.type, 1) == 1);
success = success && (file.write(&c.flags, 1) == 1);
success = success && (file.write(&unused, 1) == 1);
success = success && (file.write((uint8_t *) &reserved, 4) == 4);
success = success && (file.write((uint8_t *) &c.out_path_len, 1) == 1);
success = success && (file.write((uint8_t *) &c.last_advert_timestamp, 4) == 4);
success = success && (file.write(c.out_path, 64) == 64);
if (!success) break; // write failed
}
file.close();
}
}
void setClock(uint32_t timestamp) {
uint32_t curr = getRTCClock()->getCurrentTime();
if (timestamp > curr) {
getRTCClock()->setCurrentTime(timestamp);
Serial.println(" (OK - clock set!)");
} else {
Serial.println(" (ERR: clock cannot go backwards)");
}
}
void importCard(const char* command) {
while (*command == ' ') command++; // skip leading spaces
if (memcmp(command, "meshcore://", 11) == 0) {
command += 11; // skip the prefix
char *ep = strchr(command, 0); // find end of string
while (ep > command) {
ep--;
if (mesh::Utils::isHexChar(*ep)) break; // found tail end of card
*ep = 0; // remove trailing spaces and other junk
}
int len = strlen(command);
if (len % 2 == 0) {
len >>= 1; // halve, for num bytes
if (mesh::Utils::fromHex(tmp_buf, len, command)) {
importContact(tmp_buf, len);
return;
}
}
}
Serial.println(" error: invalid format");
}
protected:
float getAirtimeBudgetFactor() const override {
return _prefs.airtime_factor;
}
int calcRxDelay(float score, uint32_t air_time) const override {
return 0; // disable rxdelay
}
bool allowPacketForward(const mesh::Packet* packet) override {
return true;
}
void onDiscoveredContact(ContactInfo& contact, bool is_new, uint8_t path_len, const uint8_t* path) override {
// TODO: if not in favs, prompt to add as fav(?)
Serial.printf("ADVERT from -> %s\n", contact.name);
Serial.printf(" type: %s\n", getTypeName(contact.type));
Serial.print(" public key: "); mesh::Utils::printHex(Serial, contact.id.pub_key, PUB_KEY_SIZE); Serial.println();
saveContacts();
}
void onContactPathUpdated(const ContactInfo& contact) override {
Serial.printf("PATH to: %s, path_len=%d\n", contact.name, (uint32_t) contact.out_path_len);
saveContacts();
}
ContactInfo* processAck(const uint8_t *data) override {
if (memcmp(data, &expected_ack_crc, 4) == 0) { // got an ACK from recipient
Serial.printf(" Got ACK! (round trip: %d millis)\n", _ms->getMillis() - last_msg_sent);
// NOTE: the same ACK can be received multiple times!
expected_ack_crc = 0; // reset our expected hash, now that we have received ACK
return NULL; // TODO: really should return ContactInfo pointer
}
//uint32_t crc;
//memcpy(&crc, data, 4);
//MESH_DEBUG_PRINTLN("unknown ACK received: %08X (expected: %08X)", crc, expected_ack_crc);
return NULL;
}
void onMessageRecv(const ContactInfo& from, mesh::Packet* pkt, uint32_t sender_timestamp, const char *text) override {
Serial.printf("(%s) MSG -> from %s\n", pkt->isRouteDirect() ? "DIRECT" : "FLOOD", from.name);
Serial.printf(" %s\n", text);
if (strcmp(text, "clock sync") == 0) { // special text command
setClock(sender_timestamp + 1);
}
}
void onCommandDataRecv(const ContactInfo& from, mesh::Packet* pkt, uint32_t sender_timestamp, const char *text) override {
}
void onCLICommandRecv(const ContactInfo& contact, mesh::Packet* pkt, uint32_t sender_timestamp, const char *text, char* reply) override {
}
void onSignedMessageRecv(const ContactInfo& from, mesh::Packet* pkt, uint32_t sender_timestamp, const uint8_t *sender_prefix, const char *text) override {
}
void onChannelMessageRecv(const mesh::GroupChannel& channel, mesh::Packet* pkt, uint32_t timestamp, const char *text) override {
if (pkt->isRouteDirect()) {
Serial.printf("PUBLIC CHANNEL MSG -> (Direct!)\n");
} else {
Serial.printf("PUBLIC CHANNEL MSG -> (Flood) hops %d\n", pkt->path_len);
}
Serial.printf(" %s\n", text);
}
uint8_t onContactRequest(const ContactInfo& contact, uint32_t sender_timestamp, const uint8_t* data, uint8_t len, uint8_t* reply) override {
return 0; // unknown
}
void onContactResponse(const ContactInfo& contact, const uint8_t* data, uint8_t len) override {
// not supported
}
uint32_t calcFloodTimeoutMillisFor(uint32_t pkt_airtime_millis) const override {
return SEND_TIMEOUT_BASE_MILLIS + (FLOOD_SEND_TIMEOUT_FACTOR * pkt_airtime_millis);
}
uint32_t calcDirectTimeoutMillisFor(uint32_t pkt_airtime_millis, uint8_t path_len) const override {
uint8_t path_hash_count = path_len & 63;
return SEND_TIMEOUT_BASE_MILLIS +
( (pkt_airtime_millis*DIRECT_SEND_PERHOP_FACTOR + DIRECT_SEND_PERHOP_EXTRA_MILLIS) * (path_hash_count + 1));
}
void onSendTimeout() override {
Serial.println(" ERROR: timed out, no ACK.");
}
public:
MyMesh(mesh::Radio& radio, StdRNG& rng, mesh::RTCClock& rtc, SimpleMeshTables& tables)
: BaseChatMesh(radio, *new ArduinoMillis(), rng, rtc, *new StaticPoolPacketManager(16), tables)
{
// defaults
memset(&_prefs, 0, sizeof(_prefs));
_prefs.airtime_factor = 1.0;
strcpy(_prefs.node_name, "NONAME");
_prefs.freq = LORA_FREQ;
_prefs.tx_power_dbm = LORA_TX_POWER;
command[0] = 0;
curr_recipient = NULL;
}
float getFreqPref() const { return _prefs.freq; }
int8_t getTxPowerPref() const { return _prefs.tx_power_dbm; }
void begin(FILESYSTEM& fs) {
_fs = &fs;
BaseChatMesh::begin();
#if defined(NRF52_PLATFORM)
IdentityStore store(fs, "");
#elif defined(RP2040_PLATFORM)
IdentityStore store(fs, "/identity");
store.begin();
#else
IdentityStore store(fs, "/identity");
#endif
if (!store.load("_main", self_id, _prefs.node_name, sizeof(_prefs.node_name))) { // legacy: node_name was from identity file
// Need way to get some entropy to seed RNG
Serial.println("Press ENTER to generate key:");
char c = 0;
while (c != '\n') { // wait for ENTER to be pressed
if (Serial.available()) c = Serial.read();
}
((StdRNG *)getRNG())->begin(millis());
self_id = mesh::LocalIdentity(getRNG()); // create new random identity
int count = 0;
while (count < 10 && (self_id.pub_key[0] == 0x00 || self_id.pub_key[0] == 0xFF)) { // reserved id hashes
self_id = mesh::LocalIdentity(getRNG()); count++;
}
store.save("_main", self_id);
}
// load persisted prefs
if (_fs->exists("/node_prefs")) {
#if defined(RP2040_PLATFORM)
File file = _fs->open("/node_prefs", "r");
#else
File file = _fs->open("/node_prefs");
#endif
if (file) {
file.read((uint8_t *) &_prefs, sizeof(_prefs));
file.close();
}
}
loadContacts();
_public = addChannel("Public", PUBLIC_GROUP_PSK); // pre-configure Andy's public channel
}
void savePrefs() {
#if defined(NRF52_PLATFORM)
_fs->remove("/node_prefs");
File file = _fs->open("/node_prefs", FILE_O_WRITE);
#elif defined(RP2040_PLATFORM)
File file = _fs->open("/node_prefs", "w");
#else
File file = _fs->open("/node_prefs", "w", true);
#endif
if (file) {
file.write((const uint8_t *)&_prefs, sizeof(_prefs));
file.close();
}
}
void showWelcome() {
Serial.println("===== MeshCore Chat Terminal =====");
Serial.println();
Serial.printf("WELCOME %s\n", _prefs.node_name);
mesh::Utils::printHex(Serial, self_id.pub_key, PUB_KEY_SIZE);
Serial.println();
Serial.println(" (enter 'help' for basic commands)");
Serial.println();
}
void sendSelfAdvert(int delay_millis) {
auto pkt = createSelfAdvert(_prefs.node_name, _prefs.node_lat, _prefs.node_lon);
if (pkt) {
sendFlood(pkt, delay_millis);
}
}
// ContactVisitor
void onContactVisit(const ContactInfo& contact) override {
Serial.printf(" %s - ", contact.name);
char tmp[40];
int32_t secs = contact.last_advert_timestamp - getRTCClock()->getCurrentTime();
AdvertTimeHelper::formatRelativeTimeDiff(tmp, secs, false);
Serial.println(tmp);
}
void handleCommand(const char* command) {
while (*command == ' ') command++; // skip leading spaces
if (memcmp(command, "send ", 5) == 0) {
if (curr_recipient) {
const char *text = &command[5];
uint32_t est_timeout;
int result = sendMessage(*curr_recipient, getRTCClock()->getCurrentTime(), 0, text, expected_ack_crc, est_timeout);
if (result == MSG_SEND_FAILED) {
Serial.println(" ERROR: unable to send.");
} else {
last_msg_sent = _ms->getMillis();
Serial.printf(" (message sent - %s)\n", result == MSG_SEND_SENT_FLOOD ? "FLOOD" : "DIRECT");
}
} else {
Serial.println(" ERROR: no recipient selected (use 'to' cmd).");
}
} else if (memcmp(command, "public ", 7) == 0) { // send GroupChannel msg
uint8_t temp[5+MAX_TEXT_LEN+32];
uint32_t timestamp = getRTCClock()->getCurrentTime();
memcpy(temp, &timestamp, 4); // mostly an extra blob to help make packet_hash unique
temp[4] = 0; // attempt and flags
sprintf((char *) &temp[5], "%s: %s", _prefs.node_name, &command[7]); // <sender>: <msg>
temp[5 + MAX_TEXT_LEN] = 0; // truncate if too long
int len = strlen((char *) &temp[5]);
auto pkt = createGroupDatagram(PAYLOAD_TYPE_GRP_TXT, _public->channel, temp, 5 + len);
if (pkt) {
sendFlood(pkt);
Serial.println(" Sent.");
} else {
Serial.println(" ERROR: unable to send");
}
} else if (memcmp(command, "list", 4) == 0) { // show Contact list, by most recent
int n = 0;
if (command[4] == ' ') { // optional param, last 'N'
n = atoi(&command[5]);
}
scanRecentContacts(n, this);
} else if (strcmp(command, "clock") == 0) { // show current time
uint32_t now = getRTCClock()->getCurrentTime();
DateTime dt = DateTime(now);
Serial.printf( "%02d:%02d - %d/%d/%d UTC\n", dt.hour(), dt.minute(), dt.day(), dt.month(), dt.year());
} else if (memcmp(command, "time ", 5) == 0) { // set time (to epoch seconds)
uint32_t secs = _atoi(&command[5]);
setClock(secs);
} else if (memcmp(command, "to ", 3) == 0) { // set current recipient
curr_recipient = searchContactsByPrefix(&command[3]);
if (curr_recipient) {
Serial.printf(" Recipient %s now selected.\n", curr_recipient->name);
} else {
Serial.println(" Error: Name prefix not found.");
}
} else if (strcmp(command, "to") == 0) { // show current recipient
if (curr_recipient) {
Serial.printf(" Current: %s\n", curr_recipient->name);
} else {
Serial.println(" Err: no recipient selected");
}
} else if (strcmp(command, "advert") == 0) {
auto pkt = createSelfAdvert(_prefs.node_name, _prefs.node_lat, _prefs.node_lon);
if (pkt) {
sendZeroHop(pkt);
Serial.println(" (advert sent, zero hop).");
} else {
Serial.println(" ERR: unable to send");
}
} else if (strcmp(command, "reset path") == 0) {
if (curr_recipient) {
resetPathTo(*curr_recipient);
saveContacts();
Serial.println(" Done.");
}
} else if (memcmp(command, "card", 4) == 0) {
Serial.printf("Hello %s\n", _prefs.node_name);
auto pkt = createSelfAdvert(_prefs.node_name, _prefs.node_lat, _prefs.node_lon);
if (pkt) {
uint8_t len = pkt->writeTo(tmp_buf);
releasePacket(pkt); // undo the obtainNewPacket()
mesh::Utils::toHex(hex_buf, tmp_buf, len);
Serial.println("Your MeshCore biz card:");
Serial.print("meshcore://"); Serial.println(hex_buf);
Serial.println();
} else {
Serial.println(" Error");
}
} else if (memcmp(command, "import ", 7) == 0) {
importCard(&command[7]);
} else if (memcmp(command, "set ", 4) == 0) {
const char* config = &command[4];
if (memcmp(config, "af ", 3) == 0) {
_prefs.airtime_factor = atof(&config[3]);
savePrefs();
Serial.println(" OK");
} else if (memcmp(config, "name ", 5) == 0) {
StrHelper::strncpy(_prefs.node_name, &config[5], sizeof(_prefs.node_name));
savePrefs();
Serial.println(" OK");
} else if (memcmp(config, "lat ", 4) == 0) {
_prefs.node_lat = atof(&config[4]);
savePrefs();
Serial.println(" OK");
} else if (memcmp(config, "lon ", 4) == 0) {
_prefs.node_lon = atof(&config[4]);
savePrefs();
Serial.println(" OK");
} else if (memcmp(config, "tx ", 3) == 0) {
_prefs.tx_power_dbm = atoi(&config[3]);
savePrefs();
Serial.println(" OK - reboot to apply");
} else if (memcmp(config, "freq ", 5) == 0) {
_prefs.freq = atof(&config[5]);
savePrefs();
Serial.println(" OK - reboot to apply");
} else {
Serial.printf(" ERROR: unknown config: %s\n", config);
}
} else if (memcmp(command, "ver", 3) == 0) {
Serial.println(FIRMWARE_VER_TEXT);
} else if (memcmp(command, "help", 4) == 0) {
Serial.println("Commands:");
Serial.println(" set {name|lat|lon|freq|tx|af} {value}");
Serial.println(" card");
Serial.println(" import {biz card}");
Serial.println(" clock");
Serial.println(" time <epoch-seconds>");
Serial.println(" list {n}");
Serial.println(" to <recipient name or prefix>");
Serial.println(" to");
Serial.println(" send <text>");
Serial.println(" advert");
Serial.println(" reset path");
Serial.println(" public <text>");
} else {
Serial.print(" ERROR: unknown command: "); Serial.println(command);
}
}
void loop() {
BaseChatMesh::loop();
int len = strlen(command);
// `command` must stay NUL-terminated within its bounds. If it ever isn't,
// strlen() above can return >= sizeof(command) and the loop below would then
// index past the buffer, so clamp defensively.
if (len >= (int)sizeof(command)) {
command[0] = 0;
len = 0;
}
while (Serial.available() && len < sizeof(command)-1) {
char c = Serial.read();
if (c != '\n') {
command[len++] = c;
command[len] = 0;
}
Serial.print(c);
}
if (len == sizeof(command)-1) { // buffer full: treat as a completed line
command[sizeof(command)-2] = '\r'; // place end-of-line marker inside the buffer
command[sizeof(command)-1] = 0; // keep the buffer NUL-terminated
}
if (len > 0 && command[len - 1] == '\r') { // received complete line
command[len - 1] = 0; // replace newline with C string null terminator
handleCommand(command);
command[0] = 0; // reset command buffer
}
}
};
StdRNG fast_rng;
SimpleMeshTables tables;
MyMesh the_mesh(radio_driver, fast_rng, rtc_clock, tables);
void halt() {
while (1) ;
}
void setup() {
Serial.begin(115200);
board.begin();
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.begin();
#endif
if (!radio_init()) { halt(); }
fast_rng.begin(radio_driver.getRngSeed());
#if defined(NRF52_PLATFORM)
InternalFS.begin();
the_mesh.begin(InternalFS);
#elif defined(RP2040_PLATFORM)
LittleFS.begin();
the_mesh.begin(LittleFS);
#elif defined(ESP32)
SPIFFS.begin(true);
the_mesh.begin(SPIFFS);
#else
#error "need to define filesystem"
#endif
radio_driver.setParams(the_mesh.getFreqPref(), LORA_BW, LORA_SF, LORA_CR);
radio_driver.setTxPower(the_mesh.getTxPowerPref());
the_mesh.showWelcome();
// send out initial Advertisement to the mesh
#if ENABLE_ADVERT_ON_BOOT == 1
the_mesh.sendSelfAdvert(1200); // add slight delay
#endif
}
void loop() {
the_mesh.loop();
rtc_clock.tick();
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.loop();
#endif
}
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