/*
 * CSB Fake Player Guard
 * Copyright (C) 2026 counter-strike-boost.com
 *
 * Mitigates fake-player / FakeFull floods: caps concurrent connections per IP,
 * and drops clients that connect but never finish the handshake or send any
 * usercmds within a timeout (counted from CmdStart).
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version. It is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See <https://www.gnu.org/licenses/> for details.
 */

#include <amxmodx>
#include <fakemeta>

new const PLUGIN[] = "CSB Fake Player Guard"
new const VERSION[] = "1.0.0"
new const AUTHOR[]  = "counter-strike-boost.com"

#define TASK_BASE 31337

new g_pEnabled, g_pTimeout, g_pMaxPerIp

new g_iCmds[33]
new bool:g_bInGame[33]
new g_szIp[33][24]

public plugin_init()
{
    register_plugin(PLUGIN, VERSION, AUTHOR)

    g_pEnabled  = register_cvar("csb_fpg_enabled", "1")
    g_pTimeout  = register_cvar("csb_fpg_timeout", "12")
    g_pMaxPerIp = register_cvar("csb_fpg_maxperip", "3")

    register_forward(FM_CmdStart, "fwCmdStart")
}

public client_connect(id)
{
    g_iCmds[id]   = 0
    g_bInGame[id] = false
    get_user_ip(id, g_szIp[id], charsmax(g_szIp[]), 1)

    if (!get_pcvar_num(g_pEnabled))
        return

    // concurrent connections from the same address
    new same = countIp(g_szIp[id], id)

    if (same >= get_pcvar_num(g_pMaxPerIp))
    {
        log_amx("[CSB FakeGuard] %s already has %d connections - dropping new one", g_szIp[id], same)
        dropClient(id, "too many connections from your address")
        return
    }

    set_task(float(get_pcvar_num(g_pTimeout)), "taskHandshake", TASK_BASE + id)
}

public client_putinserver(id)
{
    g_bInGame[id] = true
}

public fwCmdStart(id)
{
    if (id >= 1 && id <= 32)
        g_iCmds[id]++

    return FMRES_IGNORED
}

public taskHandshake(taskid)
{
    new id = taskid - TASK_BASE

    if (id < 1 || id > 32 || !is_user_connected(id))
        return

    // a genuine client is in the game and has produced input by now
    if (!g_bInGame[id] && g_iCmds[id] == 0)
    {
        new authid[35]
        get_user_authid(id, authid, charsmax(authid))

        log_amx("[CSB FakeGuard] slot %d from %s <%s> never finished the handshake - dropping", id, g_szIp[id], authid)
        dropClient(id, "incomplete connection")
    }
}

countIp(const ip[], exclude)
{
    new players[32], num
    get_players(players, num)

    new c = 0

    for (new i = 0; i < num; i++)
    {
        new pid = players[i]

        if (pid == exclude)
            continue

        new pip[24]
        get_user_ip(pid, pip, charsmax(pip), 1)

        if (equal(pip, ip))
            c++
    }

    return c
}

dropClient(id, const reason[])
{
    server_cmd("kick #%d ^"CSB Fake Guard: %s^"", get_user_userid(id), reason)
    server_exec()
}