1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
|
#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
#elif defined (_WIN32) && ! defined (__MINGW32__)
# define USE_WINCRYPT
#endif
/* getentropy() vs rand()+time()+getpid() */
#ifdef USE_GETENTROPY
#if defined (__linux__) || defined (__APPLE__)
# include <sys/random.h>
#else
# include <unistd.h>
#endif
#elif defined (USE_WINCRYPT)
# define WIN32_LEAN_AND_MEAN
# include <Windows.h>
# include <wincrypt.h>
#else
# include <time.h>
/* getpid() on Windows */
# if defined (_WIN32) && ! defined (__MINGW32__)
# include <io.h>
# else
# include <unistd.h>
# endif
#endif
#define CLASS(ch, chars) \
{ \
.c = ch, \
.letters = chars, \
.size = sizeof(chars) - 1, \
},
struct grammar_class {
char c;
char *letters;
int size;
};
struct grammar_class classes[] = {
CLASSES
};
int const classes_n = sizeof(classes) / sizeof(classes[0]);
#ifdef USE_WINCRYPT
HCRYPTPROV win_rng = NULL;
#endif
bool init_rng(void)
{
#ifdef USE_WINCRYPT
CryptAcquireContext(
&win_rng,
NULL,
NULL,
PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT
);
if (!win_rng)
return false;
#elif ! defined (USE_GETENTROPY) && ! defined (USE_WINCRYPT)
/*
* TODO: seed better RNG
* this isn't very good, but it's enough(?) for now
*
* anything else we could use on general posix systems?
* perhaps /dev/urandom is a better fallback before doing this
*/
srand(time(NULL) + getpid() % 420 - 69);
#endif
return true;
}
unsigned int get_rng(void)
{
unsigned int r;
#ifdef USE_GETENTROPY
getentropy(&r, sizeof(r));
#elif defined (USE_WINCRYPT)
/* TODO: This could fail. Figure out how to handle */
CryptGenRandom(win_rng, sizeof(r), (BYTE *) &r);
#else
r = rand();
#endif
return r;
}
char grammar_buf[STATIC_BUFFER_SIZE + 1] = DEFAULT_GRAMMAR;
char password_buf[STATIC_BUFFER_SIZE + 1];
char *build_grammar(int triplets, int specials, int numbers, int *grammar_size)
{
*grammar_size = triplets * 3 + specials + numbers;
char *build = grammar_buf;
if (*grammar_size > STATIC_BUFFER_SIZE) {
build = malloc(*grammar_size + 1);
if (build == NULL) {
perror("malloc");
return NULL;
}
}
build[*grammar_size] = 0;
if (triplets > 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;
char *grammar = grammar_buf;
int grammar_size = sizeof(DEFAULT_GRAMMAR) - 1;
char *password = password_buf;
if (argc == 2) {
if (strcmp(argv[1], "--help") == 0) {
printf("\
passgen - a small, customisable password generator\n\
Usage: %s\n\
%s <grammar>\n\
%s <#triplets ('Cvc')> <#symbols> <#numbers>\n\
%s --help\n\
Hints:\n\
- No arguments generates with the default grammar.\n\
- If three numbers are provided, a password will be generated in the 'standard form', <triplets><symbols><numbers>.\n\
Compile-time options (edit `config.h` to customise!):\n\
- Default grammar: %s\n", argv[0], argv[0], argv[0], argv[0], grammar_buf);
printf(" - Grammar mappings:\n");
for (int i = 0; i < classes_n; ++i) {
printf(" - '%c' => \"%s\"\n", classes[i].c, classes[i].letters);
}
return 0;
}
/* 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]), &grammar_size);
if (grammar == NULL) {
fprintf(stderr, "ERROR: Could not initialise memory for password grammar.\n");
err = true;
goto cleanup;
}
}
if (grammar_size > STATIC_BUFFER_SIZE) {
password = malloc(grammar_size + 1);
if (password == NULL) {
perror("malloc");
err = true;
goto cleanup;
}
}
password[grammar_size] = 0;
if (!init_rng()) {
fprintf(stderr, "ERROR: Could not initialise RNG.\n");
err = true;
goto cleanup;
}
for (int i = 0; i < grammar_size; ++i) {
char c = grammar[i];
bool caps = c >= 'A' && c <= 'Z';
if (caps)
c += 'a' - 'A';
struct grammar_class *class = NULL;
for (int j = 0; j < classes_n; ++j) {
if (c == classes[j].c) {
class = &classes[j];
break;
}
}
if (class == NULL) {
fprintf(stderr, "ERROR: Invalid grammar character '%c'.\n", c);
err = true;
goto cleanup;
}
do {
password[i] = class->letters[get_rng() % class->size];
if (caps && password[i] >= 'a' && password[i] <= 'z')
password[i] -= 'a' - 'A';
} while (i != 0 && password[i] == password[i - 1]);
}
printf("%s\n", password);
cleanup:
#ifdef USE_WINCRYPT
CryptReleaseContext(win_rng, 0);
#endif
/* TODO: this && kinda sucks, would like a better but still fast way */
if (grammar != grammar_buf && grammar != argv[1])
free(grammar);
if (password != password_buf)
free(password);
if (err)
return 1;
return 0;
}
|
