/mandos/release

/*  -*- coding: utf-8 -*- */

/*

 * Passprompt - Read a password from the terminal and print it

 *

 * Copyright © 2007-2008 Teddy Hogeborn and Björn Påhlsson.

 * 

 * 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

 * <http://www.gnu.org/licenses/>.

 * 

 * Contact the authors at <https://www.fukt.bsnet.se/~belorn/> and

 * <https://www.fukt.bsnet.se/~teddy/>.

 */

#define _GNU_SOURCE		/* getline() */

#define _FORTIFY_SOURCE 2

#include <termios.h> 		/* struct termios, tcsetattr(),

				   TCSAFLUSH, tcgetattr(), ECHO */

#include <unistd.h>		/* struct termios, tcsetattr(),

				   STDIN_FILENO, TCSAFLUSH,

				   tcgetattr(), ECHO */

#include <signal.h>		/* sig_atomic_t, raise(), struct

				   sigaction, sigemptyset(),

				   sigaction(), sigaddset(), SIGINT,

				   SIGQUIT, SIGHUP, SIGTERM */

#include <stddef.h>		/* NULL, size_t */

#include <sys/types.h>		/* ssize_t */

#include <stdlib.h>		/* EXIT_SUCCESS, EXIT_FAILURE,

				   getopt_long */

#include <stdio.h>		/* fprintf(), stderr, getline(),

				   stdin, feof(), perror(), fputc(),

				   stdout, getopt_long */

#include <errno.h>		/* errno, EINVAL */

#include <iso646.h>		/* or, not */

#include <stdbool.h>		/* bool, false, true */

#include <string.h> 		/* strlen, rindex, strncmp, strcmp */

#include <getopt.h>		/* getopt_long */

volatile bool quit_now = false;

bool debug = false;

void termination_handler(__attribute__((unused))int signum){

  quit_now = true;

}

int main(int argc, char **argv){

  ssize_t ret;

  size_t n;

  struct termios t_new, t_old;

  char *buffer = NULL;

  char *prefix = NULL;

  int status = EXIT_SUCCESS;

  struct sigaction old_action,

    new_action = { .sa_handler = termination_handler,

		   .sa_flags = 0 };

  while (true){

    static struct option long_options[] = {

      {"debug", no_argument, (int *)&debug, 1},

      {"prefix", required_argument, 0, 'p'},

      {0, 0, 0, 0} };

    int option_index = 0;

    ret = getopt_long (argc, argv, "p:", long_options, &option_index);

    if (ret == -1){

      break;

    }

    switch(ret){

    case 0:

      break;

    case 'p':

      prefix = optarg;

      break;

    default:

      fprintf(stderr, "bad arguments\n");

      exit(EXIT_FAILURE);

    }

  }

  if (debug){

    fprintf(stderr, "Starting %s\n", argv[0]);

  }

  if (debug){

    fprintf(stderr, "Storing current terminal attributes\n");

  }

  if (tcgetattr(STDIN_FILENO, &t_old) != 0){

    return EXIT_FAILURE;

  }

  sigemptyset(&new_action.sa_mask);

  sigaddset(&new_action.sa_mask, SIGINT);

  sigaddset(&new_action.sa_mask, SIGQUIT);

  sigaddset(&new_action.sa_mask, SIGHUP);

  sigaddset(&new_action.sa_mask, SIGTERM);

  sigaction(SIGINT, NULL, &old_action);

  if (old_action.sa_handler != SIG_IGN)

    sigaction(SIGINT, &new_action, NULL);

  sigaction(SIGQUIT, NULL, &old_action);

  if (old_action.sa_handler != SIG_IGN)

    sigaction(SIGQUIT, &new_action, NULL);

  sigaction(SIGHUP, NULL, &old_action);

  if (old_action.sa_handler != SIG_IGN)

    sigaction(SIGHUP, &new_action, NULL);

  sigaction(SIGTERM, NULL, &old_action);

  if (old_action.sa_handler != SIG_IGN)

    sigaction(SIGTERM, &new_action, NULL);

  if (debug){

    fprintf(stderr, "Removing echo flag from terminal attributes\n");

  }

  t_new = t_old;

  t_new.c_lflag &= ~ECHO;

  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t_new) != 0){

    perror("tcsetattr-echo");

    return EXIT_FAILURE;

  }

  if (debug){

    fprintf(stderr, "Waiting for input from stdin \n");

  }

  while(true){

    if (quit_now){

      status = EXIT_FAILURE;

      break;

    }

    if(prefix){

      fprintf(stderr, "%s Password: ", prefix);

    } else {

      fprintf(stderr, "Password: ");

    }      

    ret = getline(&buffer, &n, stdin);

    if (ret > 0){

      fprintf(stdout, "%s", buffer);

      status = EXIT_SUCCESS;

      break;

    }

    // ret == 0 makes no other sence than to retry to read from stdin

    if (ret < 0){

      if (errno != EINTR and not feof(stdin)){

	perror("getline");

	status = EXIT_FAILURE;

	break;

      }

    }

    fputc('\n', stderr);

  }

  if (debug){

    fprintf(stderr, "Restoring terminal attributes\n");

  }

  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t_old) != 0){

    perror("tcsetattr+echo");

  }

  if (debug){

    fprintf(stderr, "%s is exiting\n", argv[0]);

  }

  return status;

}