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#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#if defined (__linux__) \
|| defined (__APPLE__) \
|| defined (__FreeBSD__) \
|| defined (__OpenBSD__)
# define USE_GETENTROPY 1
#endif
/* getentropy() vs rand()+time()+getpid() */
#ifdef USE_GETENTROPY
#if defined (__linux__) || defined (__APPLE__)
# include <sys/random.h>
#else
# include <unistd.h>
#endif
#else
#include <time.h>
/* getpid() on Windows */
#if defined (_WIN32) && ! defined (__MINGW32__)
#include <io.h>
#else
#include <unistd.h>
#endif
#endif
#define CLASS(c, chars) \
case c: \
class = chars; \
class_size = sizeof(chars)-1; \
break;
void init_rng(void)
{
/* For now, this is only needed on rand() */
#ifndef USE_GETENTROPY
/*
* TODO: seed better RNG
* this isn't very good, but it's enough(?) for now
*
* on linux we use the `getrandom` api which is supposedly
* what crypto uses to generate. potentially on win we
* can use the crypto thing (but it's more complicated
* to invoke).
*
* anything else we could use on posix systems?
*/
srand(time(NULL) + getpid() % 420 - 69);
#endif
}
unsigned int get_rng(void)
{
#ifdef USE_GETENTROPY
unsigned int r;
getentropy(&r, sizeof(r));
return r;
#else
return rand();
#endif
}
char *build_grammar(int triplets, int specials, int numbers)
{
if (triplets < 1) {
fprintf(stderr, "ERROR: Cannot have less than one triplet.");
return NULL;
}
int grammar_size = triplets * 3 + specials + numbers;
char *build = malloc(grammar_size + 1);
if (build == NULL) {
perror("malloc");
return NULL;
}
build[grammar_size] = 0;
memcpy(build, "Cvc", 3);
for (int i = 1; i < triplets; ++i)
memcpy(build + (i * 3), "cvc", 3);
memset(build + (triplets * 3), '!', specials);
memset(build + (triplets * 3) + specials, '#', numbers);
return build;
}
int main(int argc, char *argv[])
{
bool err = false;
bool custom_grammar = false;
char *grammar = DEFAULT_GRAMMAR;
int grammar_size = sizeof(DEFAULT_GRAMMAR) - 1;
if (argc == 2) {
/* Take first argument as the grammar */
grammar = argv[1];
grammar_size = strlen(grammar);
} else if (argc == 4) {
/*
* Take arguments as triplets, specials, numbers
* atoi might be scuffed but so be it (it just goes = 0 if invalid input)
*/
grammar = build_grammar(atoi(argv[1]), atoi(argv[2]), atoi(argv[3]));
if (grammar == NULL) {
err = true;
goto cleanup;
}
custom_grammar = true;
}
char *password = malloc(grammar_size + 1);
if (password == NULL) {
perror("malloc");
err = true;
goto cleanup;
}
password[grammar_size] = 0;
init_rng();
for (int i = 0; i < grammar_size; ++i) {
char c = grammar[i];
bool caps = false;
if (c >= 'A' && c <= 'Z') {
caps = true;
c += 'a' - 'A';
}
char *class;
int class_size = 0;
switch (c) {
CLASSES
default:
fprintf(stderr, "ERROR: Invalid grammar character '%c'.\n", c);
err = true;
goto cleanup;
}
do {
password[i] = class[get_rng() % class_size] - (caps ? 'a' - 'A' : 0);
} while (i != 0 && password[i] == password[i - 1]);
}
printf("%s\n", password);
cleanup:
if (custom_grammar)
free(grammar);
if (password)
free(password);
if (err)
return 1;
return 0;
}
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