/*
 * ProFTPD: mod_xclient
 *
 * Copyright (c) 2018 Manuel Mausz
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
 */

#define MOD_XCLIENT_VERSION "mod_xclient/0.1.0"

#include "conf.h"
#include "privs.h"

static const char *trace_channel = "xclient";

static int xclient_engine = FALSE;

/* command handlers */
MODRET xclient_xclient(cmd_rec *cmd)
{
  if (xclient_engine == FALSE)
    return PR_DECLINED(cmd);

  if (cmd->argc < 2)
    return PR_DECLINED(cmd);

  if (strncasecmp(cmd->argv[1], "XCLIENT", 7) == 0) {
    if (cmd->argc < 4) {
      pr_response_add_err(R_501, _("Invalid number of parameters"));
      pr_cmd_set_errno(cmd, EINVAL);
      errno = EINVAL;
      return PR_ERROR(cmd);
    }

    const pr_netaddr_t *remote_addr = NULL;
    unsigned int remote_port = 0;

    for (unsigned int i = 2; i < cmd->argc; ++i) {
      const char *param = cmd->argv[i];
      pr_trace_msg(trace_channel, 5, "parsing parameter '%s'", param);
      if (strncasecmp(param, "ADDR=", 5) == 0) {
        remote_addr = pr_netaddr_get_addr2(session.pool, param + 5, NULL,
            PR_NETADDR_GET_ADDR_FL_EXCL_DNS);
        if (remote_addr == NULL) {
          pr_response_add_err(R_501, _("%s: Invalid IP address provided"),
              param + 5);
          pr_cmd_set_errno(cmd, EINVAL);
          errno = EINVAL;
          return PR_ERROR(cmd);
        }
      }
      else if (strncasecmp(param, "PORT=", 5) == 0) {
        char *tmp = NULL;
        unsigned long res = strtoul(param + 5, &tmp, 10);
        if (tmp == NULL || *tmp != '\0' || res <= 0 || res > 65535) {
          pr_response_add_err(R_501, _("%s: Invalid port provided"),
              param + 5);
          pr_cmd_set_errno(cmd, EINVAL);
          errno = EINVAL;
          return PR_ERROR(cmd);
        }

        remote_port = res;
      }
      else {
        pr_response_add_err(R_500, _("'%s' not understood"), param);
        pr_cmd_set_errno(cmd, EINVAL);
        errno = EINVAL;
        return PR_ERROR(cmd);
      }
    }

    if (remote_addr != NULL && remote_port > 0) {
      session.c->remote_addr = remote_addr;
      session.c->remote_port = remote_port;

      /* now perform reverse DNS lookups */
      if (ServerUseReverseDNS) {
        int reverse_dns = pr_netaddr_set_reverse_dns(ServerUseReverseDNS);
        session.c->remote_name = pr_netaddr_get_dnsstr(session.c->remote_addr);
        pr_netaddr_set_reverse_dns(reverse_dns);
      }
      else
        session.c->remote_name = pr_netaddr_get_ipstr(session.c->remote_addr);

      pr_netaddr_set_sess_addrs();

      /* find the new class for this session */
      session.conn_class = pr_class_match_addr(session.c->remote_addr);

      pr_log_debug(DEBUG0, MOD_XCLIENT_VERSION
          ": new client remote address name: %s/%s",
          pr_netaddr_get_ipstr(pr_netaddr_get_sess_remote_addr()),
          pr_netaddr_get_sess_remote_name());
      pr_trace_msg(trace_channel, 5, ": new client remote address name: %s/%s",
          pr_netaddr_get_ipstr(pr_netaddr_get_sess_remote_addr()),
          pr_netaddr_get_sess_remote_name());
    }

    pr_response_add(R_200, _("SITE %s command successful"),
      (char *)cmd->argv[1]);
    return PR_HANDLED(cmd);
  }

  return PR_DECLINED(cmd);
}

/* configuration handlers */
MODRET set_xclient_engine(cmd_rec *cmd)
{
  CHECK_ARGS(cmd, 1);
  CHECK_CONF(cmd, CONF_ROOT|CONF_VIRTUAL|CONF_GLOBAL);

  int engine = get_boolean(cmd, 1);
  if (engine == -1)
    CONF_ERROR(cmd, "expected Boolean parameter");

  config_rec *c = add_config_param(cmd->argv[0], 1, NULL);
  c->argv[0] = palloc(c->pool, sizeof(int));
  *((int *)c->argv[0]) = engine;

  return PR_HANDLED(cmd);
}

/* initialization routines */
static int xclient_sess_init(void)
{
  config_rec *c = NULL;
  c = find_config(main_server->conf, CONF_PARAM, "XClientEngine", FALSE);
  if (c != NULL)
    xclient_engine = *((int *)c->argv[0]);
  return 0;
}

/* module api tables */
static conftable xclient_conftab[] =
{
  { "XClientEngine", set_xclient_engine, NULL },
  { NULL }
};

static cmdtable xclient_cmdtab[] =
{
  { CMD, C_SITE, G_NONE, xclient_xclient, FALSE, FALSE, CL_MISC },
  { 0, NULL }
};

module xclient_module =
{
  /* always NULL */
  NULL, NULL,

  /* module api version 2.0 */
  0x20,

  /* module name */
  "xclient",

  /* module configuration handler table */
  xclient_conftab,

  /* module command handler table */
  xclient_cmdtab,

  /* module authentication handler table */
  NULL,

  /* module initialization function */
  NULL,

  /* module session initialization function */
  xclient_sess_init,

  /* module version */
  MOD_XCLIENT_VERSION
};