Unique topic names per device

Disabled by default with MQTT_UNIQUE_TOPIC

Author: peterharperuk

pico_w/wifi/mqtt/mqtt_client.c

@@ -32,11 +32,15 @@
 #include MQTT_CERT_INC
 #endif
 
+#ifndef MQTT_TOPIC_LEN
+#define MQTT_TOPIC_LEN 100
+#endif
+
 typedef struct {
     mqtt_client_t* mqtt_client_inst;
     struct mqtt_connect_client_info_t mqtt_client_info;
     char data[MQTT_OUTPUT_RINGBUF_SIZE];
-    char topic[100];
+    char topic[MQTT_TOPIC_LEN];
     uint32_t len;
     ip_addr_t mqtt_server_address;
     bool connect_done;
@@ -79,6 +83,15 @@ typedef struct {
 #define MQTT_WILL_MSG "0"
 #define MQTT_WILL_QOS 1
 
+#ifndef MQTT_DEVICE_NAME
+#define MQTT_DEVICE_NAME "pico"
+#endif
+
+// Set to 1 to add the client name to topics, to support multiple devices using the same server
+#ifndef MQTT_UNIQUE_TOPIC
+#define MQTT_UNIQUE_TOPIC 0
+#endif
+
 /* References for this implementation:
  * raspberry-pi-pico-c-sdk.pdf, Section '4.1.1. hardware_adc'
  * pico-examples/adc/adc_console/adc_console.c */
@@ -105,6 +118,16 @@ static void pub_request_cb(__unused void *arg, err_t err) {
     }
 }
 
+static const char *full_topic(MQTT_CLIENT_DATA_T *state, const char *name) {
+#if MQTT_UNIQUE_TOPIC
+    static char full_topic[MQTT_TOPIC_LEN];
+    snprintf(full_topic, sizeof(full_topic), "/%s%s", state->mqtt_client_info.client_id, name);
+    return full_topic;
+#else
+    return name;
+#endif
+}
+
 static void control_led(MQTT_CLIENT_DATA_T *state, bool on) {
     // Publish state on /state topic and on/off led board
     const char* message = on ? "On" : "Off";
@@ -113,14 +136,12 @@ static void control_led(MQTT_CLIENT_DATA_T *state, bool on) {
     else
         cyw43_arch_gpio_put(CYW43_WL_GPIO_LED_PIN, 0);
 
-    char state_topic[128];
-    snprintf(state_topic, sizeof(state_topic), "%s/state", state->topic);
-    mqtt_publish(state->mqtt_client_inst, state_topic, message, strlen(message), MQTT_PUBLISH_QOS, MQTT_PUBLISH_RETAIN, pub_request_cb, state);
+    mqtt_publish(state->mqtt_client_inst, full_topic(state, "/led/state"), message, strlen(message), MQTT_PUBLISH_QOS, MQTT_PUBLISH_RETAIN, pub_request_cb, state);
 }
 
 static void publish_temperature(MQTT_CLIENT_DATA_T *state) {
     static float old_temperature;
-    const char temperature_key[] = "/temperature";
+    const char *temperature_key = full_topic(state, "/temperature");
     float temperature = read_onboard_temperature(TEMPERATURE_UNITS);
     if (temperature != old_temperature) {
         old_temperature = temperature;
@@ -156,32 +177,37 @@ static void unsub_request_cb(void *arg, err_t err) {
 
 static void sub_unsub_topics(MQTT_CLIENT_DATA_T* state, bool sub) {
     mqtt_request_cb_t cb = sub ? sub_request_cb : unsub_request_cb;
-    mqtt_sub_unsub(state->mqtt_client_inst, "/led", MQTT_SUBSCRIBE_QOS, cb, state, sub);
-    mqtt_sub_unsub(state->mqtt_client_inst, "/print", MQTT_SUBSCRIBE_QOS, cb, state, sub);
-    mqtt_sub_unsub(state->mqtt_client_inst, "/ping", MQTT_SUBSCRIBE_QOS, cb, state, sub);
-    mqtt_sub_unsub(state->mqtt_client_inst, "/exit", MQTT_SUBSCRIBE_QOS, cb, state, sub);
+    mqtt_sub_unsub(state->mqtt_client_inst, full_topic(state, "/led"), MQTT_SUBSCRIBE_QOS, cb, state, sub);
+    mqtt_sub_unsub(state->mqtt_client_inst, full_topic(state, "/print"), MQTT_SUBSCRIBE_QOS, cb, state, sub);
+    mqtt_sub_unsub(state->mqtt_client_inst, full_topic(state, "/ping"), MQTT_SUBSCRIBE_QOS, cb, state, sub);
+    mqtt_sub_unsub(state->mqtt_client_inst, full_topic(state, "/exit"), MQTT_SUBSCRIBE_QOS, cb, state, sub);
 }
 
 static void mqtt_incoming_data_cb(void *arg, const u8_t *data, u16_t len, u8_t flags) {
     MQTT_CLIENT_DATA_T* state = (MQTT_CLIENT_DATA_T*)arg;
+#if MQTT_UNIQUE_TOPIC
+    const char *basic_topic = state->topic + strlen(state->mqtt_client_info.client_id) + 1;
+#else
+    const char *basic_topic = state->topic;
+#endif
     strncpy(state->data, (const char *)data, len);
     state->len = len;
     state->data[len] = '\0';
 
     DEBUG_printf("Topic: %s, Message: %s\n", state->topic, state->data);
-    if (strcmp(state->topic, "/led") == 0)
+    if (strcmp(basic_topic, "/led") == 0)
     {
-        if (lwip_stricmp((const char *)state->data, "On") == 0)
+        if (lwip_stricmp((const char *)state->data, "On") == 0 || strcmp((const char *)state->data, "1") == 0)
             control_led(state, true);
-        else if  (lwip_stricmp((const char *)state->data, "Off") == 0)
+        else if (lwip_stricmp((const char *)state->data, "Off") == 0 || strcmp((const char *)state->data, "0") == 0)
             control_led(state, false);
-    } else if (strcmp(state->topic, "/print") == 0) {
+    } else if (strcmp(basic_topic, "/print") == 0) {
         INFO_printf("%.*s\n", len, data);
-    } else if (strcmp(state->topic, "/ping") == 0) {
+    } else if (strcmp(basic_topic, "/ping") == 0) {
         char buf[11];
         snprintf(buf, sizeof(buf), "%u", to_ms_since_boot(get_absolute_time()) / 1000);
-        mqtt_publish(state->mqtt_client_inst, "/pong", buf, strlen(buf), MQTT_PUBLISH_QOS, MQTT_PUBLISH_RETAIN, pub_request_cb, state);
-    } else if (strcmp(state->topic, "/exit") == 0) {
+        mqtt_publish(state->mqtt_client_inst, full_topic(state, "/pong"), buf, strlen(buf), MQTT_PUBLISH_QOS, MQTT_PUBLISH_RETAIN, pub_request_cb, state);
+    } else if (strcmp(basic_topic, "/exit") == 0) {
         state->stop_client = true; // stop the client when ALL subscriptions are stopped
         sub_unsub_topics(state, false); // unsubscribe
     }
@@ -276,9 +302,20 @@ int main(void) {
         panic("Failed to inizialize CYW43");
     }
 
-    // Use board unique id for the client id
-    static char client_id_buf[PICO_UNIQUE_BOARD_ID_SIZE_BYTES * 2 + 1];
-    pico_get_unique_board_id_string(client_id_buf, sizeof(client_id_buf));
+    // Use board unique id
+    char unique_id_buf[5];
+    pico_get_unique_board_id_string(unique_id_buf, sizeof(unique_id_buf));
+    for(int i=0; i < sizeof(unique_id_buf) - 1; i++) {
+        unique_id_buf[i] = tolower(unique_id_buf[i]);
+    }
+
+    // Generate a unique name, e.g. pico1234
+    char client_id_buf[sizeof(MQTT_DEVICE_NAME) + sizeof(unique_id_buf) - 1];
+    memcpy(&client_id_buf[0], MQTT_DEVICE_NAME, sizeof(MQTT_DEVICE_NAME) - 1);
+    memcpy(&client_id_buf[sizeof(MQTT_DEVICE_NAME) - 1], unique_id_buf, sizeof(unique_id_buf) - 1);
+    client_id_buf[sizeof(client_id_buf) - 1] = 0;
+    INFO_printf("Device name %s\n", client_id_buf);
+
     state.mqtt_client_info.client_id = client_id_buf;
     state.mqtt_client_info.keep_alive = MQTT_KEEP_ALIVE_S; // Keep alive in sec
 #if defined(MQTT_USERNAME) && defined(MQTT_PASSWORD)
@@ -288,7 +325,9 @@ int main(void) {
     state.mqtt_client_info.client_user = NULL;
     state.mqtt_client_info.client_pass = NULL;
 #endif
-    state.mqtt_client_info.will_topic = MQTT_WILL_TOPIC;
+    static char will_topic[MQTT_TOPIC_LEN];
+    strncpy(will_topic, full_topic(&state, MQTT_WILL_TOPIC), sizeof(will_topic));
+    state.mqtt_client_info.will_topic = will_topic;
     state.mqtt_client_info.will_msg = MQTT_WILL_MSG;
     state.mqtt_client_info.will_qos = MQTT_WILL_QOS;
     state.mqtt_client_info.will_retain = true;