int mqtt3_handle_connect(struct mosquitto_db *db, struct mosquitto *context)
{
char *protocol_name = NULL;
uint8_t protocol_version;
uint8_t connect_flags;
char *client_id = NULL;
char *will_payload = NULL, *will_topic = NULL;
uint16_t will_payloadlen;
struct mosquitto_message *will_struct = NULL;
uint8_t will, will_retain, will_qos, clean_session;
uint8_t username_flag, password_flag;
char *username = NULL, *password = NULL;
int i;
int rc;
struct _mosquitto_acl_user *acl_tail;
int slen;
#ifdef WITH_TLS
X509 *client_cert;
X509_NAME *name;
X509_NAME_ENTRY *name_entry;
#endif
struct _clientid_index_hash *find_cih;
struct _clientid_index_hash *new_cih;
#ifdef WITH_SYS_TREE
g_connection_count++;
#endif
/* Don't accept multiple CONNECT commands. */
if(context->state != mosq_cs_new){
mqtt3_context_disconnect(db, context);
return MOSQ_ERR_PROTOCOL;
}
if(_mosquitto_read_string(&context->in_packet, &protocol_name)){
mqtt3_context_disconnect(db, context);
return 1;
}
if(!protocol_name){
mqtt3_context_disconnect(db, context);
return 3;
}
if(strcmp(protocol_name, PROTOCOL_NAME)){
if(db->config->connection_messages == true){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Invalid protocol \"%s\" in CONNECT from %s.",
protocol_name, context->address);
}
_mosquitto_free(protocol_name);
mqtt3_context_disconnect(db, context);
return MOSQ_ERR_PROTOCOL;
}
_mosquitto_free(protocol_name);
if(_mosquitto_read_byte(&context->in_packet, &protocol_version)){
mqtt3_context_disconnect(db, context);
return 1;
}
if((protocol_version&0x7F) != PROTOCOL_VERSION){
if(db->config->connection_messages == true){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Invalid protocol version %d in CONNECT from %s.",
protocol_version, context->address);
}
_mosquitto_send_connack(context, CONNACK_REFUSED_PROTOCOL_VERSION);
mqtt3_context_disconnect(db, context);
return MOSQ_ERR_PROTOCOL;
}
if((protocol_version&0x80) == 0x80){
context->is_bridge = true;
}
if(_mosquitto_read_byte(&context->in_packet, &connect_flags)){
mqtt3_context_disconnect(db, context);
return 1;
}
clean_session = connect_flags & 0x02;
will = connect_flags & 0x04;
will_qos = (connect_flags & 0x18) >> 3;
will_retain = connect_flags & 0x20;
password_flag = connect_flags & 0x40;
username_flag = connect_flags & 0x80;
if(_mosquitto_read_uint16(&context->in_packet, &(context->keepalive))){
mqtt3_context_disconnect(db, context);
return 1;
}
if(_mosquitto_read_string(&context->in_packet, &client_id)){
mqtt3_context_disconnect(db, context);
return 1;
}
slen = strlen(client_id);
#ifdef WITH_STRICT_PROTOCOL
if(slen > 23 || slen == 0){
#else
if(slen == 0){
#endif
_mosquitto_free(client_id);
_mosquitto_send_connack(context, CONNACK_REFUSED_IDENTIFIER_REJECTED);
mqtt3_context_disconnect(db, context);
return 1;
}
/* clientid_prefixes check */
if(db->config->clientid_prefixes){
if(strncmp(db->config->clientid_prefixes, client_id, strlen(db->config->clientid_prefixes))){
_mosquitto_free(client_id);
_mosquitto_send_connack(context, CONNACK_REFUSED_NOT_AUTHORIZED);
mqtt3_context_disconnect(db, context);
return MOSQ_ERR_SUCCESS;
}
}
if(will){
will_struct = _mosquitto_calloc(1, sizeof(struct mosquitto_message));
if(!will_struct){
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_NOMEM;
goto handle_connect_error;
}
if(_mosquitto_read_string(&context->in_packet, &will_topic)){
mqtt3_context_disconnect(db, context);
rc = 1;
goto handle_connect_error;
}
if(strlen(will_topic) == 0){
/* FIXME - CONNACK_REFUSED_IDENTIFIER_REJECTED not really appropriate here. */
_mosquitto_send_connack(context, CONNACK_REFUSED_IDENTIFIER_REJECTED);
mqtt3_context_disconnect(db, context);
rc = 1;
goto handle_connect_error;
}
if(_mosquitto_read_uint16(&context->in_packet, &will_payloadlen)){
mqtt3_context_disconnect(db, context);
rc = 1;
goto handle_connect_error;
}
if(will_payloadlen > 0){
will_payload = _mosquitto_malloc(will_payloadlen);
if(!will_payload){
mqtt3_context_disconnect(db, context);
rc = 1;
goto handle_connect_error;
}
rc = _mosquitto_read_bytes(&context->in_packet, will_payload, will_payloadlen);
if(rc){
mqtt3_context_disconnect(db, context);
rc = 1;
goto handle_connect_error;
}
}
}
if(username_flag){
rc = _mosquitto_read_string(&context->in_packet, &username);
if(rc == MOSQ_ERR_SUCCESS){
if(password_flag){
rc = _mosquitto_read_string(&context->in_packet, &password);
if(rc == MOSQ_ERR_NOMEM){
rc = MOSQ_ERR_NOMEM;
goto handle_connect_error;
}else if(rc == MOSQ_ERR_PROTOCOL){
/* Password flag given, but no password. Ignore. */
password_flag = 0;
}
}
}else if(rc == MOSQ_ERR_NOMEM){
rc = MOSQ_ERR_NOMEM;
goto handle_connect_error;
}else{
/* Username flag given, but no username. Ignore. */
username_flag = 0;
}
}
#ifdef WITH_TLS
if(context->listener->use_identity_as_username){
if(!context->ssl){
_mosquitto_send_connack(context, CONNACK_REFUSED_BAD_USERNAME_PASSWORD);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
#ifdef REAL_WITH_TLS_PSK
if(context->listener->psk_hint){
/* Client should have provided an identity to get this far. */
if(!context->username){
_mosquitto_send_connack(context, CONNACK_REFUSED_BAD_USERNAME_PASSWORD);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
}else{
#endif /* REAL_WITH_TLS_PSK */
client_cert = SSL_get_peer_certificate(context->ssl);
if(!client_cert){
_mosquitto_send_connack(context, CONNACK_REFUSED_BAD_USERNAME_PASSWORD);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
name = X509_get_subject_name(client_cert);
if(!name){
_mosquitto_send_connack(context, CONNACK_REFUSED_BAD_USERNAME_PASSWORD);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
i = X509_NAME_get_index_by_NID(name, NID_commonName, -1);
if(i == -1){
_mosquitto_send_connack(context, CONNACK_REFUSED_BAD_USERNAME_PASSWORD);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
name_entry = X509_NAME_get_entry(name, i);
context->username = _mosquitto_strdup((char *)ASN1_STRING_data(name_entry->value));
if(!context->username){
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
#ifdef REAL_WITH_TLS_PSK
}
#endif /* REAL_WITH_TLS_PSK */
}else{
#endif /* WITH_TLS */
if(username_flag){
rc = mosquitto_unpwd_check(db, username, password);
if(rc == MOSQ_ERR_AUTH){
_mosquitto_send_connack(context, CONNACK_REFUSED_BAD_USERNAME_PASSWORD);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}else if(rc == MOSQ_ERR_INVAL){
goto handle_connect_error;
}
context->username = username;
context->password = password;
username = NULL; /* Avoid free() in error: below. */
password = NULL;
}
if(!username_flag && db->config->allow_anonymous == false){
_mosquitto_send_connack(context, CONNACK_REFUSED_NOT_AUTHORIZED);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
#ifdef WITH_TLS
}
#endif
/* Find if this client already has an entry. This must be done *after* any security checks. */
HASH_FIND_STR(db->clientid_index_hash, client_id, find_cih);
if(find_cih){
i = find_cih->db_context_index;
/* Found a matching client */
if(db->contexts[i]->sock == -1){
/* Client is reconnecting after a disconnect */
/* FIXME - does anything else need to be done here? */
}else{
/* Client is already connected, disconnect old version */
if(db->config->connection_messages == true){
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Client %s already connected, closing old connection.", client_id);
}
}
db->contexts[i]->clean_session = clean_session;
mqtt3_context_cleanup(db, db->contexts[i], false);
db->contexts[i]->state = mosq_cs_connected;
db->contexts[i]->address = _mosquitto_strdup(context->address);
db->contexts[i]->sock = context->sock;
db->contexts[i]->listener = context->listener;
db->contexts[i]->last_msg_in = mosquitto_time();
db->contexts[i]->last_msg_out = mosquitto_time();
db->contexts[i]->keepalive = context->keepalive;
db->contexts[i]->pollfd_index = context->pollfd_index;
#ifdef WITH_TLS
db->contexts[i]->ssl = context->ssl;
#endif
if(context->username){
db->contexts[i]->username = _mosquitto_strdup(context->username);
}
context->sock = -1;
#ifdef WITH_TLS
context->ssl = NULL;
#endif
context->state = mosq_cs_disconnecting;
context = db->contexts[i];
if(context->msgs){
mqtt3_db_message_reconnect_reset(context);
}
}
context->id = client_id;
client_id = NULL;
context->clean_session = clean_session;
context->ping_t = 0;
// Add the client ID to the DB hash table here
new_cih = _mosquitto_malloc(sizeof(struct _clientid_index_hash));
if(!new_cih){
_mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error: Out of memory.");
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_NOMEM;
goto handle_connect_error;
}
new_cih->id = context->id;
new_cih->db_context_index = context->db_index;
HASH_ADD_KEYPTR(hh, db->clientid_index_hash, context->id, strlen(context->id), new_cih);
#ifdef WITH_PERSISTENCE
if(!clean_session){
db->persistence_changes++;
}
#endif
/* Associate user with its ACL, assuming we have ACLs loaded. */
if(db->acl_list){
acl_tail = db->acl_list;
while(acl_tail){
if(context->username){
if(acl_tail->username && !strcmp(context->username, acl_tail->username)){
context->acl_list = acl_tail;
break;
}
}else{
if(acl_tail->username == NULL){
context->acl_list = acl_tail;
break;
}
}
acl_tail = acl_tail->next;
}
}else{
context->acl_list = NULL;
}
if(will_struct){
if(mosquitto_acl_check(db, context, will_topic, MOSQ_ACL_WRITE) != MOSQ_ERR_SUCCESS){
_mosquitto_send_connack(context, CONNACK_REFUSED_NOT_AUTHORIZED);
mqtt3_context_disconnect(db, context);
rc = MOSQ_ERR_SUCCESS;
goto handle_connect_error;
}
context->will = will_struct;
context->will->topic = will_topic;
if(will_payload){
context->will->payload = will_payload;
context->will->payloadlen = will_payloadlen;
}else{
context->will->payload = NULL;
context->will->payloadlen = 0;
}
context->will->qos = will_qos;
context->will->retain = will_retain;
}
if(db->config->connection_messages == true){
_mosquitto_log_printf(NULL, MOSQ_LOG_NOTICE, "New client connected from %s as %s (c%d, k%d).", context->address, context->id, context->clean_session, context->keepalive);
}
context->state = mosq_cs_connected;
return _mosquitto_send_connack(context, CONNACK_ACCEPTED);
handle_connect_error:
if(client_id) _mosquitto_free(client_id);
if(username) _mosquitto_free(username);
if(password) _mosquitto_free(password);
if(will_payload) _mosquitto_free(will_payload);
if(will_topic) _mosquitto_free(will_topic);
if(will_struct) _mosquitto_free(will_struct);
return rc;
}
int mqtt3_handle_disconnect(struct mosquitto_db *db, struct mosquitto *context)
{
if(!context){
return MOSQ_ERR_INVAL;
}
if(context->in_packet.remaining_length != 0){
return MOSQ_ERR_PROTOCOL;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "Received DISCONNECT from %s", context->id);
context->state = mosq_cs_disconnecting;
mqtt3_context_disconnect(db, context);
return MOSQ_ERR_SUCCESS;
}
int mqtt3_handle_subscribe(struct mosquitto_db *db, struct mosquitto *context)
{
int rc = 0;
int rc2;
uint16_t mid;
char *sub;
uint8_t qos;
uint8_t *payload = NULL, *tmp_payload;
uint32_t payloadlen = 0;
int len;
char *sub_mount;
if(!context) return MOSQ_ERR_INVAL;
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "Received SUBSCRIBE from %s", context->id);
/* FIXME - plenty of potential for memory leaks here */
if(_mosquitto_read_uint16(&context->in_packet, &mid)) return 1;
while(context->in_packet.pos < context->in_packet.remaining_length){
sub = NULL;
if(_mosquitto_read_string(&context->in_packet, &sub)){
if(payload) _mosquitto_free(payload);
return 1;
}
if(sub){
if(_mosquitto_read_byte(&context->in_packet, &qos)){
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(qos > 2){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Invalid QoS in subscription command from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(_mosquitto_fix_sub_topic(&sub)){
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(!strlen(sub)){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Empty subscription string from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(context->listener && context->listener->mount_point){
len = strlen(context->listener->mount_point) + strlen(sub) + 1;
sub_mount = _mosquitto_calloc(len, sizeof(char));
if(!sub_mount){
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return MOSQ_ERR_NOMEM;
}
snprintf(sub_mount, len, "%s%s", context->listener->mount_point, sub);
_mosquitto_free(sub);
sub = sub_mount;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "\t%s (QoS %d)", sub, qos);
rc2 = mqtt3_sub_add(db, context, sub, qos, &db->subs);
if(rc2 == MOSQ_ERR_SUCCESS){
if(mqtt3_retain_queue(db, context, sub, qos)) rc = 1;
}else if(rc2 != -1){
rc = rc2;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_SUBSCRIBE, "%s %d %s", context->id, qos, sub);
_mosquitto_free(sub);
tmp_payload = _mosquitto_realloc(payload, payloadlen + 1);
if(tmp_payload){
payload = tmp_payload;
payload[payloadlen] = qos;
payloadlen++;
}else{
if(payload) _mosquitto_free(payload);
return MOSQ_ERR_NOMEM;
}
}
}
if(_mosquitto_send_suback(context, mid, payloadlen, payload)) rc = 1;
_mosquitto_free(payload);
#ifdef WITH_PERSISTENCE
db->persistence_changes++;
#endif
return rc;
}
int mqtt3_handle_subscribe(struct mosquitto_db *db, struct mosquitto *context)
{
int rc = 0;
int rc2;
uint16_t mid;
char *sub;
uint8_t qos;
uint8_t *payload = NULL, *tmp_payload;
uint32_t payloadlen = 0;
int len;
char *sub_mount;
if(!context) return MOSQ_ERR_INVAL;
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "Received SUBSCRIBE from %s", context->id);
/* FIXME - plenty of potential for memory leaks here */
if(context->protocol == mosq_p_mqtt311){
if((context->in_packet.command&0x0F) != 0x02){
return MOSQ_ERR_PROTOCOL;
}
}
if(_mosquitto_read_uint16(&context->in_packet, &mid)) return 1;
g_epoll_subscribe_num++;
while(context->in_packet.pos < context->in_packet.remaining_length){
sub = NULL;
if(_mosquitto_read_string(&context->in_packet, &sub)){
if(payload) _mosquitto_free(payload);
return 1;
}
if(sub){
if(!strlen(sub)){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Empty subscription string from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(mosquitto_sub_topic_check(sub)){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Invalid subscription string from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(_mosquitto_read_byte(&context->in_packet, &qos)){
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(qos > 2){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Invalid QoS in subscription command from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(context->listener && context->listener->mount_point){
len = strlen(context->listener->mount_point) + strlen(sub) + 1;
sub_mount = _mosquitto_malloc(len+1);
if(!sub_mount){
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return MOSQ_ERR_NOMEM;
}
snprintf(sub_mount, len, "%s%s", context->listener->mount_point, sub);
sub_mount[len] = '\0';
_mosquitto_free(sub);
sub = sub_mount;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "\t%s (QoS %d)", sub, qos);
#if 0
/* FIXME
* This section has been disabled temporarily. mosquitto_acl_check
* calls mosquitto_topic_matches_sub, which can't cope with
* checking subscriptions that have wildcards against ACLs that
* have wildcards. Bug #1374291 is related.
*
* It's a very difficult problem when an ACL looks like foo/+/bar
* and a subscription request to foo/# is made.
*
* This should be changed to using MOSQ_ACL_SUBSCRIPTION in the
* future anyway.
*/
if(context->protocol == mosq_p_mqtt311){
rc = mosquitto_acl_check(db, context, sub, MOSQ_ACL_READ);
switch(rc){
case MOSQ_ERR_SUCCESS:
break;
case MOSQ_ERR_ACL_DENIED:
qos = 0x80;
break;
default:
_mosquitto_free(sub);
return rc;
}
}
#endif
if(qos != 0x80){
rc2 = mqtt3_sub_add(db, context, sub, qos, &db->subs);
if(rc2 == MOSQ_ERR_SUCCESS){
if(mqtt3_retain_queue(db, context, sub, qos)) rc = 1;
}else if(rc2 != -1){
rc = rc2;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_SUBSCRIBE, "%s %d %s", context->id, qos, sub);
}
_mosquitto_free(sub);
tmp_payload = _mosquitto_realloc(payload, payloadlen + 1);
if(tmp_payload){
payload = tmp_payload;
payload[payloadlen] = qos;
payloadlen++;
}else{
if(payload) _mosquitto_free(payload);
return MOSQ_ERR_NOMEM;
}
}
}
if(context->protocol == mosq_p_mqtt311){
if(payloadlen == 0){
/* No subscriptions specified, protocol error. */
return MOSQ_ERR_PROTOCOL;
}
}
if(_mosquitto_send_suback(context, mid, payloadlen, payload)) rc = 1;
_mosquitto_free(payload);
#ifdef WITH_PERSISTENCE
db->persistence_changes++;
#endif
return rc;
}
int mqtt3_handle_subscribe(struct mosquitto_db *db, struct mosquitto *context)
{
int rc = 0;
int rc2;
uint16_t mid;
char *sub;
uint8_t qos;
uint8_t *payload = NULL, *tmp_payload;//SUB的返回包为SUBACK，结构为每一行代表对应的一个topic的QOS
uint32_t payloadlen = 0;
int len;
char *sub_mount;
if(!context) return MOSQ_ERR_INVAL;
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "Received SUBSCRIBE from %s", context->id);
/* FIXME - plenty of potential for memory leaks here */
if(_mosquitto_read_uint16(&context->in_packet, &mid)) return 1;
while(context->in_packet.pos < context->in_packet.remaining_length){
//SUBSCRIBE消息包括msgid，后面就是topic的列表,一个个取就行
sub = NULL;
if(_mosquitto_read_string(&context->in_packet, &sub)){
if(payload) _mosquitto_free(payload);
return 1;
}
if(sub){
if(_mosquitto_read_byte(&context->in_packet, &qos)){//1个byte的QOS，高位6为空
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(qos > 2){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Invalid QoS in subscription command from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(_mosquitto_fix_sub_topic(&sub)){//把重复的斜杠去掉://////some//aa// -> some/aa/
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(!strlen(sub)){
_mosquitto_log_printf(NULL, MOSQ_LOG_INFO, "Empty subscription string from %s, disconnecting.",
context->address);
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return 1;
}
if(context->listener && context->listener->mount_point){
len = strlen(context->listener->mount_point) + strlen(sub) + 1;
sub_mount = _mosquitto_calloc(len, sizeof(char));
if(!sub_mount){
_mosquitto_free(sub);
if(payload) _mosquitto_free(payload);
return MOSQ_ERR_NOMEM;
}
snprintf(sub_mount, len, "%s%s", context->listener->mount_point, sub);
_mosquitto_free(sub);
sub = sub_mount;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, "\t%s (QoS %d)", sub, qos);
//将当前的这个topic挂到订阅树里面，树的每一层为路径的一段,树的subs代表订阅的客户端链表，children代表子分支链表
rc2 = mqtt3_sub_add(db, context, sub, qos, &db->subs);
if(rc2 == MOSQ_ERR_SUCCESS){//订阅成功了
//下面需要检查一下这个topic上面是不是有retain保留消息需要发送给这个客户端,里面又会处理一遍订阅树，其实可以合并一起处理嘛
if(mqtt3_retain_queue(db, context, sub, qos)) rc = 1;
}else if(rc2 != -1){
rc = rc2;
}
_mosquitto_log_printf(NULL, MOSQ_LOG_SUBSCRIBE, "%s %d %s", context->id, qos, sub);
_mosquitto_free(sub);// 释放这个原始的字符串a/b/c
tmp_payload = _mosquitto_realloc(payload, payloadlen + 1);
if(tmp_payload){//这是要返回给客户端的QOS列表,一一对应
payload = tmp_payload;
payload[payloadlen] = qos;//QOS级别不变？如果本身的topic的级别不够的话怎么办
payloadlen++;
}else{
if(payload) _mosquitto_free(payload);
return MOSQ_ERR_NOMEM;
}
//搞定一条订阅消息，在订阅的topic上已经记录了这个连接，并且payload[]上面也增加了对应连接的qos准备返回
}
}
//发送SUBACK回包
if(_mosquitto_send_suback(context, mid, payloadlen, payload)) rc = 1;
_mosquitto_free(payload);
#ifdef WITH_PERSISTENCE
db->persistence_changes++;
#endif
return rc;
}