1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/errno.h>
4
5int ceph_armor(char *dst, const char *src, const char *end);
6int ceph_unarmor(char *dst, const char *src, const char *end);
7
8/*
9 * base64 encode/decode.
10 */
11
12static const char *pem_key =
13	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
14
15static int encode_bits(int c)
16{
17	return pem_key[c];
18}
19
20static int decode_bits(char c)
21{
22	if (c >= 'A' && c <= 'Z')
23		return c - 'A';
24	if (c >= 'a' && c <= 'z')
25		return c - 'a' + 26;
26	if (c >= '0' && c <= '9')
27		return c - '0' + 52;
28	if (c == '+')
29		return 62;
30	if (c == '/')
31		return 63;
32	if (c == '=')
33		return 0; /* just non-negative, please */
34	return -EINVAL;
35}
36
37int ceph_armor(char *dst, const char *src, const char *end)
38{
39	int olen = 0;
40	int line = 0;
41
42	while (src < end) {
43		unsigned char a, b, c;
44
45		a = *src++;
46		*dst++ = encode_bits(a >> 2);
47		if (src < end) {
48			b = *src++;
49			*dst++ = encode_bits(((a & 3) << 4) | (b >> 4));
50			if (src < end) {
51				c = *src++;
52				*dst++ = encode_bits(((b & 15) << 2) |
53						     (c >> 6));
54				*dst++ = encode_bits(c & 63);
55			} else {
56				*dst++ = encode_bits((b & 15) << 2);
57				*dst++ = '=';
58			}
59		} else {
60			*dst++ = encode_bits(((a & 3) << 4));
61			*dst++ = '=';
62			*dst++ = '=';
63		}
64		olen += 4;
65		line += 4;
66		if (line == 64) {
67			line = 0;
68			*(dst++) = '\n';
69			olen++;
70		}
71	}
72	return olen;
73}
74
75int ceph_unarmor(char *dst, const char *src, const char *end)
76{
77	int olen = 0;
78
79	while (src < end) {
80		int a, b, c, d;
81
82		if (src[0] == '\n') {
83			src++;
84			continue;
85		}
86		if (src + 4 > end)
87			return -EINVAL;
88		a = decode_bits(src[0]);
89		b = decode_bits(src[1]);
90		c = decode_bits(src[2]);
91		d = decode_bits(src[3]);
92		if (a < 0 || b < 0 || c < 0 || d < 0)
93			return -EINVAL;
94
95		*dst++ = (a << 2) | (b >> 4);
96		if (src[2] == '=')
97			return olen + 1;
98		*dst++ = ((b & 15) << 4) | (c >> 2);
99		if (src[3] == '=')
100			return olen + 2;
101		*dst++ = ((c & 3) << 6) | d;
102		olen += 3;
103		src += 4;
104	}
105	return olen;
106}
107