1
2#include <linux/errno.h>
3
4int ceph_armor(char *dst, const char *src, const char *end);
5int ceph_unarmor(char *dst, const char *src, const char *end);
6
7/*
8 * base64 encode/decode.
9 */
10
11static const char *pem_key =
12	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
13
14static int encode_bits(int c)
15{
16	return pem_key[c];
17}
18
19static int decode_bits(char c)
20{
21	if (c >= 'A' && c <= 'Z')
22		return c - 'A';
23	if (c >= 'a' && c <= 'z')
24		return c - 'a' + 26;
25	if (c >= '0' && c <= '9')
26		return c - '0' + 52;
27	if (c == '+')
28		return 62;
29	if (c == '/')
30		return 63;
31	if (c == '=')
32		return 0; /* just non-negative, please */
33	return -EINVAL;
34}
35
36int ceph_armor(char *dst, const char *src, const char *end)
37{
38	int olen = 0;
39	int line = 0;
40
41	while (src < end) {
42		unsigned char a, b, c;
43
44		a = *src++;
45		*dst++ = encode_bits(a >> 2);
46		if (src < end) {
47			b = *src++;
48			*dst++ = encode_bits(((a & 3) << 4) | (b >> 4));
49			if (src < end) {
50				c = *src++;
51				*dst++ = encode_bits(((b & 15) << 2) |
52						     (c >> 6));
53				*dst++ = encode_bits(c & 63);
54			} else {
55				*dst++ = encode_bits((b & 15) << 2);
56				*dst++ = '=';
57			}
58		} else {
59			*dst++ = encode_bits(((a & 3) << 4));
60			*dst++ = '=';
61			*dst++ = '=';
62		}
63		olen += 4;
64		line += 4;
65		if (line == 64) {
66			line = 0;
67			*(dst++) = '\n';
68			olen++;
69		}
70	}
71	return olen;
72}
73
74int ceph_unarmor(char *dst, const char *src, const char *end)
75{
76	int olen = 0;
77
78	while (src < end) {
79		int a, b, c, d;
80
81		if (src < end && src[0] == '\n')
82			src++;
83		if (src + 4 > end)
84			return -EINVAL;
85		a = decode_bits(src[0]);
86		b = decode_bits(src[1]);
87		c = decode_bits(src[2]);
88		d = decode_bits(src[3]);
89		if (a < 0 || b < 0 || c < 0 || d < 0)
90			return -EINVAL;
91
92		*dst++ = (a << 2) | (b >> 4);
93		if (src[2] == '=')
94			return olen + 1;
95		*dst++ = ((b & 15) << 4) | (c >> 2);
96		if (src[3] == '=')
97			return olen + 2;
98		*dst++ = ((c & 3) << 6) | d;
99		olen += 3;
100		src += 4;
101	}
102	return olen;
103}
104