help with hl2 server plugin

[Austin]

I need to port this old metamod "no headshots to humans" plugin to cs source. I have complied the server plugin sample but know almost nothing about the hl2 sdk.

Can anyone give me some clues on how I would port these few lines into a hl2 server plugin?

//---------------------------------------------------------------------
// Disallow headshot damange to human players
//---------------------------------------------------------------------------
void TraceLine(const float *v1, const float *v2, int fNoMonsters, edict_t *pentToSkip, TraceResult *ptr)
{
    TRACE_LINE(v1, v2, fNoMonsters, pentToSkip, ptr);
    // disallow head shots to human players
    if ( ( (1<<HITGROUP_HEAD) & (1<<ptr->iHitgroup)) &&
             !(ptr->pHit->v.flags & FL_FAKECLIENT)            )
    {
        ptr->flFraction = 1.0;
        RETURN_META(MRES_SUPERCEDE);
    }
    else
        RETURN_META(MRES_IGNORED);
}

Thanks a million.