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/*
* genpass.c: password generator
*
* Copyright (c) 2025, Přemysl Eric Janouch <p@janouch.name>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "config.h"
#undef PROGRAM_NAME
#define PROGRAM_NAME "genpass"
#include "liberty/liberty.c"
static struct str
parse_group (const char *group)
{
bool present[0x100] = {};
for (size_t i = 0; group[i]; i++)
{
unsigned char c = group[i];
if (!i || c != '-' || !group[i + 1])
present[c] = true;
else if (group[i + 1] < group[i - 1])
exit_fatal ("character ranges must be increasing");
else
for (c = group[i - 1]; ++c <= group[i + 1]; )
present[c] = true;
}
struct str alphabet = str_make ();
for (size_t i = 1; i < N_ELEMENTS (present); i++)
if (present[i])
str_append_c (&alphabet, i);
if (!alphabet.len)
exit_fatal ("empty group");
return alphabet;
}
static void
parse_program_arguments (int argc, char **argv,
unsigned long *length, struct strv *groups, struct str *alphabet)
{
static const struct opt opts[] =
{
{ 'l', "length", "CHARACTERS", 0, "set password length" },
{ 'd', "debug", NULL, 0, "run in debug mode" },
{ 'h', "help", NULL, 0, "display this help and exit" },
{ 'V', "version", NULL, 0, "output version information and exit" },
{ 0, NULL, NULL, 0, NULL }
};
struct opt_handler oh =
opt_handler_make (argc, argv, opts, "GROUP...", "Password generator.");
int c;
while ((c = opt_handler_get (&oh)) != -1)
switch (c)
{
case 'l':
if (!xstrtoul (length, optarg, 10) || *length <= 0)
print_fatal ("invalid length argument");
break;
case 'd':
g_debug_mode = true;
break;
case 'h':
opt_handler_usage (&oh, stdout);
exit (EXIT_SUCCESS);
case 'V':
printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
exit (EXIT_SUCCESS);
default:
print_error ("wrong options");
opt_handler_usage (&oh, stderr);
exit (EXIT_FAILURE);
}
argc -= optind;
argv += optind;
for (int i = 0; i < argc; i++)
{
struct str alphabet = parse_group (argv[i]);
strv_append_owned (groups, str_steal (&alphabet));
}
bool present[0x100] = {};
for (size_t i = 0; i < groups->len; i++)
for (size_t k = 0; groups->vector[i][k]; k++)
{
unsigned char c = groups->vector[i][k];
if (present[c])
exit_fatal ("groups are not disjunct");
present[c] = true;
}
for (size_t i = 1; i < N_ELEMENTS (present); i++)
if (present[i])
str_append_c (alphabet, i);
if (groups->len > *length)
exit_fatal ("the requested length is less than the number of groups");
if (!groups->len)
{
opt_handler_usage (&oh, stderr);
exit (EXIT_FAILURE);
}
opt_handler_free (&oh);
}
int
main (int argc, char *argv[])
{
unsigned long length = 8;
struct strv groups = strv_make ();
struct str alphabet = str_make ();
parse_program_arguments (argc, argv, &length, &groups, &alphabet);
unsigned seed = 0;
if (!random_bytes (&seed, sizeof seed, NULL))
exit_fatal ("failed to initialize random numbers");
srand (seed);
// Select from a joined alphabet, but make sure all groups are represented.
struct str candidate = str_make ();
while (true)
{
restart:
for (size_t i = length; i--; )
str_append_c (&candidate, alphabet.str[rand () % alphabet.len]);
for (size_t i = 0; i < groups.len; i++)
if (!strpbrk (candidate.str, groups.vector[i]))
{
str_reset (&candidate);
goto restart;
}
printf ("%s\n", candidate.str);
return 0;
}
}
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