1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 4 -*- */
2 /* vi: set expandtab shiftwidth=4 tabstop=4: */
3 /**
4 * \file
5 * <PRE>
6 * MODP_B64 - High performance base64 encoder/decoder
7 * Version 1.3 -- 17-Mar-2006
8 * http://modp.com/release/base64
9 *
10 * Copyright © 2005, 2006 Nick Galbreath -- nickg [at] modp [dot] com
11 * All rights reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions are
15 * met:
16 *
17 * Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 *
24 * Neither the name of the modp.com nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * This is the standard "new" BSD license:
41 * http://www.opensource.org/licenses/bsd-license.php
42 * </PRE>
43 */
44
45 /* public header */
46 #include "modp_b64.h"
47
48 #include "modp_b64_data.h"
49
50 #define BADCHAR 0x01FFFFFF
51
modp_b64_encode_data(char * dest,const char * str,size_t len)52 size_t modp_b64_encode_data(char* dest, const char* str, size_t len)
53 {
54 size_t i = 0;
55 uint8_t* p = (uint8_t*) dest;
56
57 /* unsigned here is important! */
58 uint8_t t1, t2, t3;
59
60 if (len > 2) {
61 for (; i < len - 2; i += 3) {
62 t1 = str[i]; t2 = str[i+1]; t3 = str[i+2];
63 *p++ = e0[t1];
64 *p++ = e1[((t1 & 0x03) << 4) | ((t2 >> 4) & 0x0F)];
65 *p++ = e1[((t2 & 0x0F) << 2) | ((t3 >> 6) & 0x03)];
66 *p++ = e2[t3];
67 }
68 }
69
70 switch (len - i) {
71 case 0:
72 break;
73 case 1:
74 t1 = str[i];
75 *p++ = e0[t1];
76 *p++ = e1[(t1 & 0x03) << 4];
77 *p++ = CHARPAD;
78 *p++ = CHARPAD;
79 break;
80 default: /* case 2 */
81 t1 = str[i]; t2 = str[i+1];
82 *p++ = e0[t1];
83 *p++ = e1[((t1 & 0x03) << 4) | ((t2 >> 4) & 0x0F)];
84 *p++ = e2[(t2 & 0x0F) << 2];
85 *p++ = CHARPAD;
86 }
87
88 return p - (uint8_t*)dest;
89 }
90
modp_b64_encode(char * dest,const char * str,size_t len)91 size_t modp_b64_encode(char* dest, const char* str, size_t len) {
92 size_t output_size = modp_b64_encode_data(dest, str, len);
93 dest[output_size] = '\0';
94 return output_size;
95 }
96
do_decode_padding(const char * src,size_t len,ModpDecodePolicy policy)97 size_t do_decode_padding(const char* src, size_t len, ModpDecodePolicy policy) {
98 if (policy == ModpDecodePolicy::kNoPaddingValidation) {
99 while (len > 0 && src[len - 1] == CHARPAD) {
100 len--;
101 }
102 } else {
103 const size_t remainder = len % 4;
104 if (policy == ModpDecodePolicy::kStrict && (remainder != 0 || len < 4))
105 return MODP_B64_ERROR;
106 if (remainder == 0) {
107 if (src[len - 1] == CHARPAD) {
108 len--;
109 if (src[len - 1] == CHARPAD) {
110 len--;
111 }
112 }
113 }
114 }
115 return len % 4 == 1 ? MODP_B64_ERROR : len;
116 }
117
modp_b64_decode(char * dest,const char * src,size_t len,ModpDecodePolicy policy)118 size_t modp_b64_decode(char* dest, const char* src, size_t len, ModpDecodePolicy policy)
119 {
120 if (len != 0)
121 len = do_decode_padding(src, len, policy);
122
123 if (len == 0 || len == MODP_B64_ERROR)
124 return len;
125
126 size_t i;
127 int leftover = len % 4;
128 size_t chunks = (leftover == 0) ? len / 4 - 1 : len /4;
129
130 uint8_t* p = (uint8_t*)dest;
131 uint32_t x = 0;
132 const uint8_t* y = (uint8_t*)src;
133 for (i = 0; i < chunks; ++i, y += 4) {
134 x = d0[y[0]] | d1[y[1]] | d2[y[2]] | d3[y[3]];
135 if (x >= BADCHAR) return MODP_B64_ERROR;
136 *p++ = ((uint8_t*)(&x))[0];
137 *p++ = ((uint8_t*)(&x))[1];
138 *p++ = ((uint8_t*)(&x))[2];
139 }
140
141 switch (leftover) {
142 case 0:
143 x = d0[y[0]] | d1[y[1]] | d2[y[2]] | d3[y[3]];
144
145 if (x >= BADCHAR) return MODP_B64_ERROR;
146 *p++ = ((uint8_t*)(&x))[0];
147 *p++ = ((uint8_t*)(&x))[1];
148 *p = ((uint8_t*)(&x))[2];
149 return (chunks+1)*3;
150 case 1: /* with padding this is an impossible case */
151 x = d0[y[0]];
152 *p = *((uint8_t*)(&x)); // i.e. first char/byte in int
153 break;
154 case 2: // * case 2, 1 output byte */
155 x = d0[y[0]] | d1[y[1]];
156 *p = *((uint8_t*)(&x)); // i.e. first char
157 break;
158 default: /* case 3, 2 output bytes */
159 x = d0[y[0]] | d1[y[1]] | d2[y[2]]; /* 0x3c */
160 *p++ = ((uint8_t*)(&x))[0];
161 *p = ((uint8_t*)(&x))[1];
162 break;
163 }
164
165 if (x >= BADCHAR) return MODP_B64_ERROR;
166
167 return 3*chunks + (6*leftover)/8;
168 }
169