3 minutes buff Songs effects using @duel

Originally posted by Lunar
How to reproduce:

• Take a Bard/Danser/Gypsy/Clown/whatever
• Use a Song Bragi/Service/whatever
• Take the buff effect with another character like Sniper
• Use the command @duel with no target player name, juste type @duel nothing else with the singer. The other character must be in the area of effect of the song before you do that.
• Stop the song, with weapon switch or adaptation

Effect:

Using the @duel, will ignore the other character in the area of effect when you will break the song. (battle_check_target function return false)
Af if the other character don't left the area (the server doesn't use skill_unit_onleft function)
It causes the song will stay 3 minutes instead of 20 seconds.


Here is my (very bad) way to fix it, I think there is a better way:

static int skill_unit_effect (struct block_list* bl, va_list ap)
{
struct skill_unit* unit = va_arg(ap,struct skill_unit*);
struct skill_unit_group* group = unit->group;
unsigned int tick = va_arg(ap,unsigned int);
unsigned int flag = va_arg(ap,unsigned int);
int skill_id;
bool dissonance;
if( (!unit->alive && !(flag&4)) || bl->prev == NULL )
  return 0;
nullpo_ret(group);
dissonance = skill_dance_switch(unit, 0);
//Necessary in case the group is deleted after calling on_place/on_out [Skotlex]
skill_id = group->skill_id;
//Target-type check.
if( !(group->bl_flag&bl->type && battle_check_target(&unit->bl,bl,group->target_flag)>0) )
{
  if( flag&4 && group->src_id == bl->id && group->state.song_dance&0x2 )
   skill_unit_onleft(skill_id, bl, tick);//Ensemble check to terminate it.
  else if ( flag&4 && skill_get_inf2(skillid)&INF2_SONG_DANCE) // Make a exception for song/dance skill
   skill_unit_onleft(skill_id, bl, tick); //Bye bye glitch duel <img src='http://rathena.org/board/public/style_emoticons/default/smile.png' class='bbc_emoticon' alt=':)' />
}
else
{
  if( flag&1 )
   skill_unit_onplace(unit,bl,tick);
  else
   skill_unit_onout(unit,bl,tick);
  if( flag&4 )
   skill_unit_onleft(skill_id, bl, tick);
}
if( dissonance ) skill_dance_switch(unit, 1);
return 0;
}