/*
   SSHSecure - a program to harden OpenSSH from defaults
   Copyright (C) 2020  Brent Saner

   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.

   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, see <https://www.gnu.org/licenses/>.
*/

package config

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"path"

	"github.com/pkg/errors"
	"r00t2.io/sysutils/exec_extra"
	"r00t2.io/sysutils/paths"
)

func ChkConfig(config *[]byte) (bool, error) {
	var sysPaths []string
	var binPath string
	var tmpConf *os.File
	var err error
	var stdout, stderr bytes.Buffer
	// sshd *requires* to be invoked with an absolute path.
	sysPaths, err = paths.GetPathEnv()
	if err != nil {
		return false, err
	}
	for _, p := range sysPaths {
		fpath := path.Join(p, "sshd")
		if exists, err := paths.RealPathExists(&fpath); err != nil {
			return false, err
		} else if !exists {
			continue
		}
		binPath = fpath
		break
	}
	tmpConf, err = ioutil.TempFile("/tmp", ".test.sshconf.")
	if err != nil {
		return false, err
	}
	defer os.Remove(tmpConf.Name())
	if err = tmpConf.Chmod(0600); err != nil {
		return false, err
	}
	if _, err = tmpConf.Write(*config); err != nil {
		return false, err
	}
	cmd := exec.Command(binPath,
		"-T", fmt.Sprintf("-f %v",
			tmpConf.Name()))
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	exitStatus, err := exec_extra.ExecCmdReturn(cmd)
	if err != nil {
		return false, err
	}
	if exitStatus != 0 {
		// TODO: also handle non-empty stderr?
		e := fmt.Sprintf("returned status/exit code %d", exitStatus)
		return false, errors.New(e)
	}
	return true, nil
}