xref: /illumos-gate/usr/src/common/iscsi/base64.c (revision f3041bfa)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #include <sys/types.h>
27 #ifdef _KERNEL
28 #include <sys/sunddi.h>
29 #include <sys/errno.h>
30 #else
31 #include <string.h>
32 #include <errno.h>
33 #endif	/* _KERNEL */
34 
35 /*
36  * base64 decoding table (from uudecode.c)
37  */
38 /* BEGIN CSTYLED */
39  static char base64_decode_tab[] = {
40 	'\377', '\377', '\377', '\377', '\377', '\377', '\377', '\377',
41 	'\377', '\377', '\377', '\377', '\377', '\377', '\377', '\377',
42 	'\377', '\377', '\377', '\377', '\377', '\377', '\377', '\377',
43 	'\377', '\377', '\377', '\377', '\377', '\377', '\377', '\377',
44 	'\377', '\377', '\377', '\377', '\377', '\377', '\377', '\377',
45 	'\377', '\377', '\377',     62, '\377', '\377', '\377',     63,
46 	    52,     53,     54,     55,     56,     57,     58,     59,
47 	    60,     61, '\377', '\377', '\377', '\377', '\377', '\377',
48 	'\377',      0,      1,      2,      3,      4,      5,      6,
49 	     7,      8,      9,     10,     11,     12,     13,     14,
50 	    15,     16,     17,     18,     19,     20,     21,     22,
51 	    23,     24,     25, '\377', '\377', '\377', '\377', '\377',
52 	'\377',     26,     27,     28,     29,     30,     31,     32,
53 	    33,     34,     35,     36,     37,     38,     39,     40,
54 	    41,     42,     43,     44,     45,     46,     47,     48,
55 	    49,     50,     51, '\377', '\377', '\377', '\377', '\377'
56 };
57 /* END CSTYLED */
58 
59 /* true if the character is in the base64 encoding table */
60 #define	validbase64(c) (('A' <= (c) && (c) <= 'Z') || \
61 		('a' <= (c) && (c) <= 'z') || \
62 		('0' <= (c) && (c) <= '9') || \
63 		(c) == '+' || (c) == '/')
64 
65 static int
66 outdec64(unsigned char *out, unsigned char *chr, int num)
67 {
68 
69 	unsigned char char1, char2, char3, char4;
70 	unsigned char *outptr = out;
71 	int rc = 0;
72 
73 	switch (num) {
74 	case 0:
75 	case 1: 	/* these are impossible */
76 	default:
77 		break;
78 	case 2:		/* 2 base64 bytes == 1 decoded byte */
79 		char1 = base64_decode_tab[chr[0]] & 0xFF;
80 		char2 = base64_decode_tab[chr[1]] & 0xFF;
81 		*(outptr++) = ((char1 << 2) & 0xFC) |
82 		    ((char2 >> 4) & 0x03);
83 		rc = 1;
84 		break;
85 	case 3:		/* 3 base64 bytes == 2 decoded bytes */
86 		char1 = base64_decode_tab[chr[0]] & 0xFF;
87 		char2 = base64_decode_tab[chr[1]] & 0xFF;
88 		char3 = base64_decode_tab[chr[2]] & 0xFF;
89 		*(outptr++) = ((char1 << 2) & 0xFC) |
90 		    ((char2 >> 4) & 0x03);
91 		*(outptr++) = ((char2 << 4) & 0xF0) |
92 		    ((char3 >> 2) & 0x0F);
93 		rc = 2;
94 		break;
95 	case 4:		/* 4 base64 bytes == 3 decoded bytes */
96 		char1 = base64_decode_tab[chr[0]] & 0xFF;
97 		char2 = base64_decode_tab[chr[1]] & 0xFF;
98 		char3 = base64_decode_tab[chr[2]] & 0xFF;
99 		char4 = base64_decode_tab[chr[3]] & 0xFF;
100 		*(outptr++) = ((char1 << 2) & 0xFC) |
101 		    ((char2 >> 4) & 0x03);
102 		*(outptr++) = ((char2 << 4) & 0xF0) |
103 		    ((char3 >> 2) & 0x0F);
104 		*(outptr++) = ((char3 << 6) & 0xC0) |
105 		    (char4 & 0x3F);
106 		rc = 3;
107 		break;
108 	}
109 	return (rc);
110 }
111 
112 #define	BUFSIZE	12
113 
114 int
115 iscsi_base64_str_to_binary(char *hstr, int hstr_len,
116     uint8_t *binary, int binary_buf_len, int *out_len)
117 {
118 	char	*iptr;
119 	uint8_t	tmp_out[BUFSIZE];
120 	int	octets, endseen, numbase64chars;
121 	unsigned char chr[4], curchr;
122 
123 	/*
124 	 * base64 decode algorith, adapted from uudecode.c
125 	 *
126 	 * A valid base64 string is a multiple of 4 bytes in length
127 	 */
128 	if ((hstr_len % 4) != 0)
129 		return (EINVAL);
130 
131 	endseen = numbase64chars = 0;
132 	*out_len = 0;
133 	iptr = hstr;
134 
135 	while (((curchr = *(iptr++)) != NULL) &&
136 	    (((uintptr_t)iptr - (uintptr_t)hstr) <= hstr_len)) {
137 		/* decode chars */
138 		if (curchr == '=') /* if end */
139 			endseen++;
140 
141 		if (validbase64(curchr))
142 			chr[numbase64chars++] = curchr;
143 		/*
144 		 * if we've gathered 4 base64 octets
145 		 * we need to decode and output them
146 		 */
147 		if (numbase64chars == 4) {
148 			octets = outdec64(tmp_out, chr, 4);
149 			numbase64chars = 0;
150 
151 			if (*out_len + octets > binary_buf_len)
152 				return (E2BIG);
153 
154 			(void) memcpy(binary + *out_len, tmp_out, octets);
155 			*out_len += octets;
156 		}
157 
158 		/*
159 		 * handle any remaining base64 octets at end
160 		 */
161 		if (endseen && numbase64chars > 0) {
162 			octets = outdec64(tmp_out, chr, numbase64chars);
163 			numbase64chars = 0;
164 			if (*out_len + octets > binary_buf_len)
165 				return (E2BIG);
166 
167 			(void) memcpy(binary + *out_len, tmp_out, octets);
168 			*out_len += octets;
169 		}
170 	}
171 
172 	return (0);
173 }
174 
175 
176 static char base64_encode_tab[] =
177 	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
178 	"abcdefghijklmnopqrstuvwxyz0123456789+/";
179 
180 #define	ENC(c)	base64_encode_tab[(c) & 0x3f]
181 
182 #define	BASE64_BUF_HAS_ROOM(bytes_needed) \
183 	((optr + (bytes_needed)) <= base64_str_buf + base64_buf_len)
184 
185 int
186 iscsi_binary_to_base64_str(uint8_t *in_buf, int in_buf_len,
187     char *base64_str_buf, int base64_buf_len)
188 {
189 	uint8_t 	*iptr;
190 	char		*optr;
191 	int		in_bytes_remaining;
192 
193 	/* base64 encode algorith, adapted from uuencode.c */
194 	iptr = in_buf;
195 	optr = base64_str_buf;
196 
197 	/*
198 	 * read must be a multiple of 3 bytes for
199 	 * this algorithm to work, and also must
200 	 * be small enough that read_size * (4/3)
201 	 * will always be 76 bytes or less, since
202 	 * base64 lines can be no longer than that
203 	 */
204 	while (iptr + 3 <= in_buf + in_buf_len) {
205 		if (!BASE64_BUF_HAS_ROOM(4))
206 			return (E2BIG);
207 
208 		*(optr++) = ENC(*iptr >> 2);
209 		*(optr++) = ENC((*iptr << 4) & 060 |
210 		    (*(iptr + 1) >> 4) & 017);
211 		*(optr++) = ENC((*(iptr + 1) << 2)
212 		    & 074 | (*(iptr + 2) >> 6) & 03);
213 		*(optr++) = ENC(*(iptr + 2) & 077);
214 
215 		iptr += 3;
216 	}
217 
218 	/* need output padding ? */
219 	in_bytes_remaining = ((uintptr_t)in_buf + in_buf_len) - (uintptr_t)iptr;
220 	/* ASSERT(in_bytes_remaining < 3); */
221 	switch (in_bytes_remaining) {
222 	case 0:
223 		/* no-op  - 24 bits of data encoded */
224 		if (!BASE64_BUF_HAS_ROOM(1))
225 			return (E2BIG);
226 		*(optr++) = '\0';
227 		break;
228 	case 1:
229 		/* 8 bits encoded - pad with 2 '=' */
230 		if (!BASE64_BUF_HAS_ROOM(5))
231 			return (E2BIG);
232 		*(optr++) = ENC((*iptr & 0xFC) >> 2);
233 		*(optr++) = ENC((*iptr & 0x03) << 4);
234 		*(optr++) = '=';
235 		*(optr++) = '=';
236 		*(optr++) = '\0';
237 		break;
238 	case 2:
239 		/* 16 bits encoded - pad with 1 '=' */
240 		if (!BASE64_BUF_HAS_ROOM(5))
241 			return (E2BIG);
242 		*(optr++) = ENC((*iptr & 0xFC) >> 2);
243 		*(optr++) = ENC(((*iptr & 0x03) << 4) |
244 		    ((*(iptr + 1) & 0xF0) >> 4));
245 		*(optr++) = ENC((*(iptr + 1) & 0x0F) << 2);
246 		*(optr++) = '=';
247 		*(optr++) = '\0';
248 		break;
249 	default:
250 		/* impossible */
251 		break;
252 	}
253 
254 	return (0);
255 }
256