/* simple password generator by Nelson Minar (minar@reed.edu)
** copyright 1991, all rights reserved.
** You can use this code as long as my name stays with it.
**
** md5 patch by W. Campbell <wcampbel@botbay.net>
** Modernization, getopt, etc for the Hybrid IRCD team
** by W. Campbell
**
** $Id: mkpasswd.c,v 1.3 2005/08/27 16:23:50 jpinto Exp $
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

#define FLAG_MD5     0x00000001
#define FLAG_DES     0x00000002
#define FLAG_SALT    0x00000004
#define FLAG_PASS    0x00000008
#define FLAG_LENGTH  0x00000010

extern char *getpass();
extern char *crypt();

char *make_des_salt();
char *make_md5_salt(int);
char *make_md5_salt_para(char *);
void usage();
static char saltChars[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789./";

int main(int argc, char *argv[])
{
  char *plaintext = NULL;
  extern char *optarg;
  extern int optind;
  int c;
  char *saltpara = NULL;
  char *salt;
  int flag = 0;
  int length = 8;

  srandom(time(NULL));

  while( (c=getopt(argc, argv, "mdh?l:s:p:")) != -1)
  {
    switch(c)
    {
      case 'm':
        flag |= FLAG_MD5;
        break;
      case 'd':
        flag |= FLAG_DES;
        break;
      case 'l':
        flag |= FLAG_LENGTH;
        length = atoi(optarg);
        break;
      case 's':
        flag |= FLAG_SALT;
        saltpara = optarg;
        break;
      case 'p':
        flag |= FLAG_PASS;
        plaintext = optarg;
        break;
      case 'h':
      case '?':
        usage();
        break;
      default:
        printf("Invalid Option: -%c\n", c);
        break;
    }
  }

  if (flag & FLAG_MD5)
  {
    if (flag & FLAG_SALT)
      salt = make_md5_salt_para(saltpara);
    else
      salt = make_md5_salt(length);
  }
  else
  {
    if (flag & FLAG_SALT)
    {
      if ((strlen(saltpara) == 2))
      {
        salt = saltpara;
      }
      else
      {
        printf("Invalid salt, please enter 2 alphanumeric characters\n");
        exit(1);
      }
    }
    else
    {
      salt = make_des_salt();
    }
  }

  if (flag & FLAG_PASS)
  {
    if (!plaintext)
      printf("Please enter a valid password\n");
  }
  else
  {
    plaintext = getpass("plaintext: ");
  }

  printf("%s\n", crypt(plaintext, salt));
  return 0;
}

char *make_des_salt()
{
  static char salt[3];
  salt[0] = saltChars[random() % 64];
  salt[1] = saltChars[random() % 64];
  salt[2] = '\0';
  return salt;
}

char *make_md5_salt_para(char *saltpara)
{
  static char salt[21];
  if (saltpara && (strlen(saltpara) <= 16))
  {
    /* sprintf used because of portability requirements, the length
    ** is checked above, so it should not be too much of a concern
    */
    sprintf(salt, "$1$%s$", saltpara);
    return salt;
  }
  printf("Invalid Salt, please use up to 16 random alphanumeric characters\n");
  exit(1);

  /* NOT REACHED */
  return NULL;
}
  
char *make_md5_salt(int length)
{
  static char salt[21];
  int i;
  if (length > 16)
  {
    printf("MD5 salt length too long\n");
    exit(0);
  }
  salt[0] = '$';
  salt[1] = '1';
  salt[2] = '$';
  for (i=3; i<(length+3); i++)
    salt[i] = saltChars[random() % 64];
  salt[length+3] = '$';
  salt[length+4] = '\0';
  return salt;
}

void usage()
{
  printf("mkpasswd [-m|-d] [-l saltlength] [-s salt] [-p plaintext]\n");
  printf("-m Generate an MD5 password\n");
  printf("-d Generate a DES password\n");
  printf("-l Specify a length for a random MD5 salt\n");
  printf("-s Specify a salt, 2 alphanumeric characters for DES, up to 16 for MD5\n");
  printf("-p Specify a plaintext password to use\n");
  printf("Example: mkpasswd -m -s 3dr -p test\n");
  exit(0);
}