toolsd.c

/*
 * VMSMOUNT - A network redirector for mounting VMware's Shared Folders in DOS
 * Copyright (C) 2022  Eduardo Casino
 *
 * toolsd.c: Minimal VMWare tools daemon
 *
 * 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA  02110-1301, USA.
 */

#include <dos.h>
#include <stdint.h>

#include "debug.h"
#include "globals.h"
#include "miniclib.h"
#include "vmtool.h"

#define HEARTBEAT_INTERVAL 18 // (1 sec)

#define TCLO_PING                       "ping"
#define TCLO_RESET                      "reset"
#define TCLO_VIX_CMD                    "Vix_1_"
#define TCLO_VIX_MOUNT                  TCLO_VIX_CMD "Mount_Volumes"
#define TCLO_SUCCESS                    "OK "
#define TCLO_ERROR                      "ERROR "
#define TCLO_RST_SUCCESS TCLO_SUCCESS   "ATR toolbox"
#define TCLO_UNKNOWN_CMD TCLO_ERROR     "Unknown command"
#define TCLO_VIX_SUCCESS TCLO_SUCCESS   "0 0"
#define TCLO_VIX_UNSUPPORTED TCLO_ERROR "6 0"

#define TCLO_CMD_MAX_LEN 160
typedef union {
    struct
    {
        uint8_t command[TCLO_CMD_MAX_LEN + 1];
        uint32_t commandLen;
    } c;
    struct
    {
        uint8_t reply[TCLO_CMD_MAX_LEN + 1];
        uint32_t replyLen;
    } r;
} TCLOMsg;

#ifdef DEBUG
#define DEB_STACK_SIZE 256
uint8_t debStack[DEB_STACK_SIZE] = {
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC,
    0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC, 0xEC};

static uint16_t dosSS;
static uint16_t dosSP;
#endif

rpc_t tclo = {
    0, // channel
    0, // cookie1
    0  // cookie2
};

void(__interrupt __far *fpPrevInt1cHandler)();

static void Int1cToolsd(union INTPACK regset)
#pragma aux Int1cToolsd "*" __parm __caller [] __modify [__ax __bx __cx __dx __si __di __es __gs __fs]
{
    // Do not use stack (see how to fix it -zu)
    static TCLOMsg msg = {0};
    static ticks = HEARTBEAT_INTERVAL;
    static uint16_t id;
    static int ret;

#ifdef DEBUG
    __asm
    {
        mov dosSS, ss
        mov dosSP, sp
        mov ax, ds
        mov ss, ax
        mov sp, (offset debStack) + DEB_STACK_SIZE
    }
#endif

    if (msg.r.replyLen || ++ticks > HEARTBEAT_INTERVAL)
    {
        ticks = 0; // Reset heartbeat counter

        ret = VMRpcSend(&tclo, &msg.r.reply, msg.r.replyLen);
        msg.r.replyLen = 0; // This also sets msg.c.commandLen to 0

        if (ret)
        {
            goto chain;
        }

        ret = VMRpcRecvLen(&tclo, &msg.c.commandLen, &id);

        if (ret || msg.c.commandLen == 0)
        {
            goto chain;
        }

        if (msg.c.commandLen > TCLO_CMD_MAX_LEN)
            msg.c.commandLen = TCLO_CMD_MAX_LEN;

        if (VMRpcRecvDat(&tclo, &msg.c.command, msg.c.commandLen, id) == 0)
        {
            if (!strncmp_local(msg.c.command, TCLO_RESET, sizeof(TCLO_RESET) - 1))
            {
                msg.r.replyLen = sizeof(TCLO_RST_SUCCESS) - 1;
                memcpy_local(&msg.r.reply, TCLO_RST_SUCCESS, msg.r.replyLen);
            }
            else if (!strncmp_local(msg.c.command, TCLO_PING, sizeof(TCLO_PING) - 1))
            {
                msg.r.replyLen = sizeof(TCLO_SUCCESS) - 1;
                memcpy_local(&msg.r.reply, TCLO_SUCCESS, msg.r.replyLen);
            }
            else if (!strncmp_local(msg.c.command, TCLO_VIX_MOUNT, sizeof(TCLO_VIX_MOUNT) - 1))
            {
                msg.r.replyLen = sizeof(TCLO_VIX_SUCCESS) - 1;
                DPRINTF("Received TCLO Vix command: %s", msg.c.command);
                memcpy_local(&msg.r.reply, TCLO_VIX_SUCCESS, msg.r.replyLen);
            }
            else if (!strncmp_local(msg.c.command, TCLO_VIX_CMD, sizeof(TCLO_VIX_CMD) - 1))
            {
                msg.r.replyLen = sizeof(TCLO_VIX_UNSUPPORTED) - 1;
                DPRINTF("Received unsupported TCLO Vix command: %s", msg.c.command);
                memcpy_local(&msg.r.reply, TCLO_VIX_UNSUPPORTED, msg.r.replyLen);
            }
            else
            {
#ifdef DEBUG
                msg.c.command[msg.c.commandLen] = '\0';
                DPRINTF("Received unsupported TCLO command: %s", msg.c.command);
#endif
                msg.r.replyLen = sizeof(TCLO_UNKNOWN_CMD) - 1;
                memcpy_local(&msg.r.reply, TCLO_UNKNOWN_CMD, msg.r.replyLen);
            }
        }
    }

chain:
#ifdef DEBUG
    __asm
    {
        mov ss, dosSS
        mov sp, dosSP
    }
#endif
    return;
}

void __declspec(naked) __far Int1cHandler(void)
{
    __asm
    {
        pusha
        push  ds
        push  es
        push  fs
        push  gs

        mov   bp, sp
        push  cs
        pop   ds

        call  Int1cToolsd

        mov   bx, word ptr [bp+28]     ; restore flags
        and   bx, 0fcffh               ; except for IF and TF
        push  bx
        popf
        pop   gs
        pop   fs
        pop   es
        pop   ds
        popa

        jmp   dword ptr cs:fpPrevInt1cHandler
    }
}