1/*
2 * Copyright (c) 2000-2002 by Solar Designer. See LICENSE.
3 */
4
5#include <stdio.h>
6#include <string.h>
7#include <unistd.h>
8#include <errno.h>
9#include <fcntl.h>
10
11#include "passwdqc.h"
12
13#define SEPARATORS			"_,.;:-!&"
14
15static int read_loop(int fd, char *buffer, int count)
16{
17	int offset, block;
18
19	offset = 0;
20	while (count > 0) {
21		block = read(fd, &buffer[offset], count);
22
23		if (block < 0) {
24			if (errno == EINTR) continue;
25			return block;
26		}
27		if (!block) return offset;
28
29		offset += block;
30		count -= block;
31	}
32
33	return offset;
34}
35
36char *_passwdqc_random(passwdqc_params_t *params)
37{
38	static char output[0x100];
39	int bits;
40	int use_separators, count, i;
41	unsigned int length;
42	char *start, *end;
43	int fd;
44	unsigned char bytes[2];
45
46	if (!(bits = params->random_bits))
47		return NULL;
48
49	count = 1 + ((bits - 12) + 14) / 15;
50	use_separators = ((bits + 11) / 12 != count);
51
52	length = count * 7 - 1;
53	if (length >= sizeof(output) || (int)length > params->max)
54		return NULL;
55
56	if ((fd = open("/dev/urandom", O_RDONLY)) < 0) return NULL;
57
58	length = 0;
59	do {
60		if (read_loop(fd, bytes, sizeof(bytes)) != sizeof(bytes)) {
61			close(fd);
62			return NULL;
63		}
64
65		i = (((int)bytes[1] & 0x0f) << 8) | (int)bytes[0];
66		start = _passwdqc_wordset_4k[i];
67		end = memchr(start, '\0', 6);
68		if (!end) end = start + 6;
69		if (length + (end - start) >= sizeof(output) - 1) {
70			close(fd);
71			return NULL;
72		}
73		memcpy(&output[length], start, end - start);
74		length += end - start;
75		bits -= 12;
76
77		if (use_separators && bits > 3) {
78			i = ((int)bytes[1] & 0x70) >> 4;
79			output[length++] = SEPARATORS[i];
80			bits -= 3;
81		} else
82		if (bits > 0)
83			output[length++] = ' ';
84	} while (bits > 0);
85
86	memset(bytes, 0, sizeof(bytes));
87	output[length] = '\0';
88
89	close(fd);
90
91	return output;
92}
93