Fix possible leak during connect.

Closes #2057. Thanks to Przemysław Zygmunt.

ChangeLog.txt

@@ -1,6 +1,7 @@
 Broker:
 - Fix exporting of executable symbols on BSD when building via makefile.
 - Fix some minor memory leaks on exit only.
+- Fix possible memory leak on connect. Closes #2057.
 
 Clients:
 - Fix config files truncating options after the first space. Closes #2059.

src/handle_connect.c

@@ -351,7 +351,6 @@ static int will__read(struct mosquitto *context, const char *client_id, struct m
  }else{
  send__connack(context, 0, CONNACK_REFUSED_NOT_AUTHORIZED, NULL);
  }
- context__disconnect(context);
  rc = MOSQ_ERR_PAYLOAD_SIZE;
  goto error_cleanup;
  }
@@ -835,6 +834,7 @@ int handle__connect(struct mosquitto *context)
  if(context->auth_method){
  rc = mosquitto_security_auth_start(context, false, auth_data, auth_data_len, &auth_data_out, &auth_data_out_len);
  mosquitto__free(auth_data);
+ auth_data = NULL;
  if(rc == MOSQ_ERR_SUCCESS){
  return connect__on_authorised(context, auth_data_out, auth_data_out_len);
  }else if(rc == MOSQ_ERR_AUTH_CONTINUE){
@@ -844,22 +844,23 @@ int handle__connect(struct mosquitto *context)
  return rc;
  }else{
  free(auth_data_out);
+ auth_data_out = NULL;
  will__clear(context);
  if(rc == MOSQ_ERR_AUTH){
  send__connack(context, 0, MQTT_RC_NOT_AUTHORIZED, NULL);
  mosquitto__free(context->id);
  context->id = NULL;
- return MOSQ_ERR_PROTOCOL;
+ goto handle_connect_error;
  }else if(rc == MOSQ_ERR_NOT_SUPPORTED){
  /* Client has requested extended authentication, but we don't support it. */
  send__connack(context, 0, MQTT_RC_BAD_AUTHENTICATION_METHOD, NULL);
  mosquitto__free(context->id);
  context->id = NULL;
- return MOSQ_ERR_PROTOCOL;
+ goto handle_connect_error;
  }else{
  mosquitto__free(context->id);
  context->id = NULL;
- return rc;
+ goto handle_connect_error;
  }
  }
  }else{
@@ -885,12 +886,11 @@ int handle__connect(struct mosquitto *context)
  }else{
  send__connack(context, 0, CONNACK_REFUSED_NOT_AUTHORIZED, NULL);
  }
- context__disconnect(context);
  rc = MOSQ_ERR_AUTH;
  goto handle_connect_error;
  break;
  default:
- context__disconnect(context);
+ rc = MOSQ_ERR_UNKNOWN;
  goto handle_connect_error;
  break;
  }