libmosquitto 3 Mosquitto Project Library calls libmosquitto MQTT version 3.1 client library This is an overview of how to use libmosquitto to create MQTT aware client programs. There may be separate man pages on each of the functions described here in the future. There is also a binding for libmosquitto for C++ and a Python implementation. They are not documented here but operate in a similar way. This is fairly incomplete, please see mosquitto.h for a better description of the functions. All public functions in libmosquitto have the prefix "mosquitto_". Any other functions defined in the source code are to be treated as private functions and may change between any release. Do not use these functions! int mosquitto_lib_version int *major int *minor int *revision Obtain version information about the library. If any of major, minor or revision are not NULL they will return the corresponding version numbers. The return value is an integer representation of the complete version number (e.g. 1009001 for 1.9.1) that can be used for comparisons. int mosquitto_lib_init int mosquitto_lib_cleanup Call mosquitto_lib_init() before using any of the other library functions and mosquitto_lib_cleanup() after finishing with the library. struct mosquitto *mosquitto_new const char *id bool clean_session void *userdata Create a new mosquitto client instance. void mosquitto_destroy struct mosquitto *mosq Use to free memory associated with a mosquitto client instance. int mosquitto_reinitialise struct mosquitto *mosq const char *id bool clean_session void *userdata int mosquitto_username_pw_set struct mosquitto *mosq const char *username const char *password int mosquitto_tls_set struct mosquitto *mosq const char *cafile const char *capath const char *certfile const char *keyfile int (*pw_callback)(char *buf, int size, int rwflag, void *userdata) int mosquitto_tls_opts_set struct mosquitto *mosq int cert_reqs const char *tls_version const char *ciphers int mosquitto_tls_insecure_set struct mosquitto *mosq bool value int mosquitto_tls_psk_set struct mosquitto *mosq const char *psk const char *identity const char *ciphers int mosquitto_will_set struct mosquitto *mosq const char *topic int payloadlen const void *payload int qos bool retain int mosquitto_will_clear struct mosquitto *mosq int mosquitto_connect struct mosquitto *mosq const char *host int port int keepalive int mosquitto_connect_bind struct mosquitto *mosq const char *host int port int keepalive const char *bind_address int mosquitto_connect_async struct mosquitto *mosq const char *host int port int keepalive int mosquitto_connect_bind_async struct mosquitto *mosq const char *host int port int keepalive const char *bind_address int mosquitto_reconnect struct mosquitto *mosq int mosquitto_reconnect_async struct mosquitto *mosq int mosquitto_disconnect struct mosquitto *mosq int mosquitto_publish struct mosquitto *mosq int *mid const char *topic int payloadlen const void *payload int qos bool retain int mosquitto_subscribe struct mosquitto *mosq int *mid const char *sub int qos int mosquitto_unsubscribe struct mosquitto *mosq int *mid const char *sub int mosquitto_loop struct mosquitto *mosq int timeout int max_packets int mosquitto_loop_read struct mosquitto *mosq int max_packets int mosquitto_loop_write struct mosquitto *mosq int max_packets int mosquitto_loop_misc struct mosquitto *mosq int mosquitto_loop_forever struct mosquitto *mosq int timeout int max_packets int mosquitto_socket struct mosquitto *mosq bool mosquitto_want_write struct mosquitto *mosq int mosquitto_loop_start struct mosquitto *mosq int mosquitto_loop_stop struct mosquitto *mosq bool force int mosquitto_max_inflight_messages_set struct mosquitto *mosq unsigned int max_inflight_messages int mosquitto_reconnect_delay_set struct mosquitto *mosq unsigned int reconnect_delay unsigned int reconnect_delay_max bool reconnect_exponential_backoff int mosquitto_user_data_set struct mosquitto *mosq void *userdata int mosquitto_connect_callback_set struct mosquitto *mosq void (*on_connect)(struct mosquitto *, void *, int) int mosquitto_disconnect_callback_set struct mosquitto *mosq void (*on_disconnect)(struct mosquitto *, void *, int) int mosquitto_publish_callback_set struct mosquitto *mosq void (*on_publish)(struct mosquitto *, void *, int) int mosquitto_message_callback_set struct mosquitto *mosq void (*on_message)(struct mosquitto *, void *, const struct mosquitto_message *) int mosquitto_subscribe_callback_set struct mosquitto *mosq void (*on_subscribe)(struct mosquitto *, void *, int, int, const int *) int mosquitto_unsubscribe_callback_set struct mosquitto *mosq void (*on_unsubscribe)(struct mosquitto *, void *, int) int mosquitto_log_callback_set struct mosquitto *mosq void (*on_unsubscribe)(struct mosquitto *, void *, int, const char *) const char *mosquitto_connack_string int connack_code int mosquitto_message_copy struct mosquitto_message *dst const struct mosquitto_message *src int mosquitto_message_free struct mosquitto_message **message const char *mosquitto_strerror int mosq_errno int mosquitto_sub_topic_tokenise const char *subtopic char ***topics int *count int mosquitto_sub_topic_tokens_free char ***topics int count int mosquitto_topic_matches_sub const char *sub const char *topic bool *result #include <stdio.h> #include <mosquitto.h> void my_message_callback(struct mosquitto *mosq, void *userdata, const struct mosquitto_message *message) { if(message->payloadlen){ printf("%s %s\n", message->topic, message->payload); }else{ printf("%s (null)\n", message->topic); } fflush(stdout); } void my_connect_callback(struct mosquitto *mosq, void *userdata, int result) { int i; if(!result){ /* Subscribe to broker information topics on successful connect. */ mosquitto_subscribe(mosq, NULL, "$SYS/#", 2); }else{ fprintf(stderr, "Connect failed\n"); } } void my_subscribe_callback(struct mosquitto *mosq, void *userdata, int mid, int qos_count, const int *granted_qos) { int i; printf("Subscribed (mid: %d): %d", mid, granted_qos[0]); for(i=1; i<qos_count; i++){ printf(", %d", granted_qos[i]); } printf("\n"); } void my_log_callback(struct mosquitto *mosq, void *userdata, int level, const char *str) { /* Pring all log messages regardless of level. */ printf("%s\n", str); } int main(int argc, char *argv[]) { int i; char *host = "localhost"; int port = 1883; int keepalive = 60; bool clean_session = true; struct mosquitto *mosq = NULL; mosquitto_lib_init(); mosq = mosquitto_new(NULL, clean_session, NULL); if(!mosq){ fprintf(stderr, "Error: Out of memory.\n"); return 1; } mosquitto_log_callback_set(mosq, my_log_callback); mosquitto_connect_callback_set(mosq, my_connect_callback); mosquitto_message_callback_set(mosq, my_message_callback); mosquitto_subscribe_callback_set(mosq, my_subscribe_callback); if(mosquitto_connect(mosq, host, port, keepalive)){ fprintf(stderr, "Unable to connect.\n"); return 1; } while(!mosquitto_loop(mosq, -1, 1)){ } mosquitto_destroy(mosq); mosquitto_lib_cleanup(); return 0; } mosquitto 8 mqtt 7 Roger Light roger@atchoo.org