int send_message(struct userNode *dest, struct userNode *src, const char *message, ...);
int send_message_type(int msg_type, struct userNode *dest, struct userNode *src, const char *message, ...);
int send_target_message(int msg_type, const char *dest, struct userNode *src, const char *format, ...);
int send_message(struct userNode *dest, struct userNode *src, const char *message, ...);
int send_message_type(int msg_type, struct userNode *dest, struct userNode *src, const char *message, ...);
int send_target_message(int msg_type, const char *dest, struct userNode *src, const char *format, ...);