int mosquitto_unsubscribe(struct mosquitto *mosq, int *mid, const char *sub)
{
if(!mosq) return MOSQ_ERR_INVAL;
if(mosq->sock == INVALID_SOCKET) return MOSQ_ERR_NO_CONN;
return _mosquitto_send_unsubscribe(mosq, mid, false, sub);
}
/* 整个.c文件就是处理客户端的连接请求，返回一个连接确认包 */
int mqtt3_handle_connack(struct mosquitto_db *db, struct mosquitto *context)
{
uint8_t byte;
uint8_t rc;
int i;
char *notification_topic;
int notification_topic_len;
char notification_payload;
if(!context){
return MOSQ_ERR_INVAL;
}
#ifdef WITH_STRICT_PROTOCOL
if(context->in_packet.remaining_length != 2){
return MOSQ_ERR_PROTOCOL;
}
#endif
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "Received CONNACK on connection %s.", context->id);
if(_mosquitto_read_byte(&context->in_packet, &byte)) return 1; // Reserved byte, not used
if(_mosquitto_read_byte(&context->in_packet, &rc)) return 1;
switch(rc){
//
case CONNACK_ACCEPTED:
// 这是一个broker客户端
if(context->bridge){
// 提醒机制是怎么做的？
if(context->bridge->notifications){
notification_payload = '1';
if(context->bridge->notification_topic){
if(_mosquitto_send_real_publish(context, _mosquitto_mid_generate(context),
context->bridge->notification_topic, 1, ¬ification_payload, 1, true, 0)){
return 1;
}
mqtt3_db_messages_easy_queue(db, context, context->bridge->notification_topic, 1, 1, ¬ification_payload, 1);
}else{
notification_topic_len = strlen(context->id)+strlen("$SYS/broker/connection//state");
notification_topic = _mosquitto_malloc(sizeof(char)*(notification_topic_len+1));
if(!notification_topic) return MOSQ_ERR_NOMEM;
snprintf(notification_topic, notification_topic_len+1, "$SYS/broker/connection/%s/state", context->id);
notification_payload = '1';
if(_mosquitto_send_real_publish(context, _mosquitto_mid_generate(context),
notification_topic, 1, ¬ification_payload, 1, true, 0)){
_mosquitto_free(notification_topic);
return 1;
}
mqtt3_db_messages_easy_queue(db, context, notification_topic, 1, 1, ¬ification_payload, 1);
_mosquitto_free(notification_topic);
}
}// end of bridge notifications
// broker之间的订阅处理机制，画个图可能好理解点
for(i=0; i<context->bridge->topic_count; i++){
if(context->bridge->topics[i].direction == bd_in || context->bridge->topics[i].direction == bd_both){
if(_mosquitto_send_subscribe(context, NULL, false, context->bridge->topics[i].remote_topic, context->bridge->topics[i].qos)){
return 1;
}
}else{
if(_mosquitto_send_unsubscribe(context, NULL, false, context->bridge->topics[i].remote_topic)){
/* direction = inwards only. This means we should not be subscribed
* to the topic. It is possible that we used to be subscribed to
* this topic so unsubscribe. */
return 1;
}
}
}
}
// 原来更新的是客户端的额状态
context->state = mosq_cs_connected;
return MOSQ_ERR_SUCCESS;
// 连接错误，版本问题
case CONNACK_REFUSED_PROTOCOL_VERSION:
if(context->bridge){
context->bridge->try_private_accepted = false;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Connection Refused: unacceptable protocol version");
return 1;
//
case CONNACK_REFUSED_IDENTIFIER_REJECTED:
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Connection Refused: identifier rejected");
return 1;
//
case CONNACK_REFUSED_SERVER_UNAVAILABLE:
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Connection Refused: broker unavailable");
return 1;
//
case CONNACK_REFUSED_BAD_USERNAME_PASSWORD:
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Connection Refused: broker unavailable");
return 1;
//
case CONNACK_REFUSED_NOT_AUTHORIZED:
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Connection Refused: not authorised");
return 1;
//
default:
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Connection Refused: unknown reason");
return 1;
}
return 1;
}