constification
[exim.git] / src / src / base64.c
CommitLineData
f4d091fb
JH
1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
5/* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004, 2015 */
6/* License: GPL */
7
f9ba5e22 8/* Copyright (c) University of Cambridge 1995 - 2018 */
f4d091fb
JH
9/* See the file NOTICE for conditions of use and distribution. */
10
11
12#include "exim.h"
13#ifdef WITH_CONTENT_SCAN /* file-IO specific decode function */
14# include "mime.h"
15
16/* BASE64 decoder matrix */
17static unsigned char mime_b64[256]={
18/* 0 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
19/* 16 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
20/* 32 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 62, 128, 128, 128, 63,
21/* 48 */ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 128, 128, 128, 255, 128, 128,
22/* 64 */ 128, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
23/* 80 */ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 128, 128, 128, 128, 128,
24/* 96 */ 128, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
25/* 112 */ 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 128, 128, 128, 128, 128,
26/* 128 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
27/* 144 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
28/* 160 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
29/* 176 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
30/* 192 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
31/* 208 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
32/* 224 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
33/* 240 */ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128
34};
35
36/* decode base64 MIME part */
37ssize_t
38mime_decode_base64(FILE * in, FILE * out, uschar * boundary)
39{
40uschar ibuf[MIME_MAX_LINE_LENGTH], obuf[MIME_MAX_LINE_LENGTH];
d7978c0f 41uschar *opos;
f4d091fb
JH
42ssize_t len, size = 0;
43int bytestate = 0;
44
45opos = obuf;
46
47while (Ufgets(ibuf, MIME_MAX_LINE_LENGTH, in) != NULL)
48 {
49 if (boundary != NULL
50 && Ustrncmp(ibuf, "--", 2) == 0
51 && Ustrncmp((ibuf+2), boundary, Ustrlen(boundary)) == 0
52 )
53 break;
54
d7978c0f 55 for (uschar * ipos = ibuf ; *ipos != '\r' && *ipos != '\n' && *ipos; ++ipos)
f4d091fb
JH
56 if (*ipos == '=') /* skip padding */
57 ++bytestate;
58
59 else if (mime_b64[*ipos] == 128) /* skip bad characters */
60 mime_set_anomaly(MIME_ANOMALY_BROKEN_BASE64);
61
62 /* simple state-machine */
63 else switch((bytestate++) & 3)
64 {
65 case 0:
66 *opos = mime_b64[*ipos] << 2; break;
67 case 1:
68 *opos++ |= mime_b64[*ipos] >> 4;
69 *opos = mime_b64[*ipos] << 4; break;
70 case 2:
71 *opos++ |= mime_b64[*ipos] >> 2;
72 *opos = mime_b64[*ipos] << 6; break;
73 case 3:
74 *opos++ |= mime_b64[*ipos]; break;
75 }
76
77 /* something to write? */
78 len = opos - obuf;
79 if (len > 0)
80 {
81 if (fwrite(obuf, 1, len, out) != len) return -1; /* error */
82 size += len;
83 /* copy incomplete last byte to start of obuf, where we continue */
84 if ((bytestate & 3) != 0)
85 *obuf = *opos;
86 opos = obuf;
87 }
88 } /* while */
89
90/* write out last byte if it was incomplete */
91if (bytestate & 3)
92 {
93 if (fwrite(obuf, 1, 1, out) != 1) return -1;
94 ++size;
95 }
96
97return size;
98}
99
100#endif /*WITH_CONTENT_SCAN*/
101
102/*************************************************
3c51463e
JH
103 *************************************************
104 *************************************************
105 *************************************************
106 *************************************************
107 *************************************************
108 *************************************************
109 *************************************************
110 *************************************************
111 *************************************************
112 *************************************************
113 *************************************************
114 *************************************************
115 *************************************************
116 *************************************************
117 *************************************************/
f4d091fb
JH
118
119
120/*************************************************
121* Decode byte-string in base 64 *
122*************************************************/
123
124/* This function decodes a string in base 64 format as defined in RFC 2045
125(MIME) and required by the SMTP AUTH extension (RFC 2554). The decoding
126algorithm is written out in a straightforward way. Turning it into some kind of
127compact loop is messy and would probably run more slowly.
128
129Arguments:
130 code points to the coded string, zero-terminated
131 ptr where to put the pointer to the result, which is in
df3def24 132 allocated store, and zero-terminated
f4d091fb
JH
133
134Returns: the number of bytes in the result,
135 or -1 if the input was malformed
136
69a70afa 137Whitespace in the input is ignored.
f4d091fb
JH
138A zero is added on to the end to make it easy in cases where the result is to
139be interpreted as text. This is not included in the count. */
140
141static uschar dec64table[] = {
142 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, /* 0-15 */
143 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, /* 16-31 */
144 255,255,255,255,255,255,255,255,255,255,255, 62,255,255,255, 63, /* 32-47 */
145 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255,255,255,255, /* 48-63 */
146 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 64-79 */
147 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255,255, /* 80-95 */
148 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 96-111 */
149 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255 /* 112-127*/
150};
151
152int
35cf75e9 153b64decode(const uschar *code, uschar **ptr)
f4d091fb 154{
cf3cd306 155
f4d091fb 156int x, y;
cf3cd306 157uschar *result;
f4d091fb 158
cf3cd306
HSHR
159{
160 int l = Ustrlen(code);
161 *ptr = result = store_get(1 + l/4 * 3 + l%4);
162}
f4d091fb
JH
163
164/* Each cycle of the loop handles a quantum of 4 input bytes. For the last
165quantum this may decode to 1, 2, or 3 output bytes. */
166
167while ((x = *code++) != 0)
168 {
69a70afa 169 if (isspace(x)) continue;
df3def24 170 /* debug_printf("b64d: '%c'\n", x); */
69a70afa 171
f4d091fb 172 if (x > 127 || (x = dec64table[x]) == 255) return -1;
69a70afa
JH
173
174 while (isspace(y = *code++)) ;
df3def24 175 /* debug_printf("b64d: '%c'\n", y); */
889d293b 176 if (y > 127 || (y = dec64table[y]) == 255)
f4d091fb
JH
177 return -1;
178
179 *result++ = (x << 2) | (y >> 4);
df3def24 180 /* debug_printf("b64d: -> %02x\n", result[-1]); */
f4d091fb 181
69a70afa 182 while (isspace(x = *code++)) ;
df3def24
JH
183 /* debug_printf("b64d: '%c'\n", x); */
184 if (x == '=') /* endmarker, but there should be another */
f4d091fb 185 {
69a70afa 186 while (isspace(x = *code++)) ;
df3def24
JH
187 /* debug_printf("b64d: '%c'\n", x); */
188 if (x != '=') return -1;
189 while (isspace(y = *code++)) ;
190 if (y != 0) return -1;
191 /* debug_printf("b64d: DONE\n"); */
192 break;
f4d091fb
JH
193 }
194 else
195 {
196 if (x > 127 || (x = dec64table[x]) == 255) return -1;
197 *result++ = (y << 4) | (x >> 2);
df3def24 198 /* debug_printf("b64d: -> %02x\n", result[-1]); */
69a70afa
JH
199
200 while (isspace(y = *code++)) ;
df3def24 201 /* debug_printf("b64d: '%c'\n", y); */
69a70afa 202 if (y == '=')
f4d091fb 203 {
df3def24
JH
204 while (isspace(y = *code++)) ;
205 if (y != 0) return -1;
206 /* debug_printf("b64d: DONE\n"); */
207 break;
f4d091fb
JH
208 }
209 else
210 {
211 if (y > 127 || (y = dec64table[y]) == 255) return -1;
212 *result++ = (x << 6) | y;
df3def24 213 /* debug_printf("b64d: -> %02x\n", result[-1]); */
f4d091fb
JH
214 }
215 }
216 }
217
218*result = 0;
219return result - *ptr;
220}
221
222
223/*************************************************
f4d091fb
JH
224* Encode byte-string in base 64 *
225*************************************************/
226
227/* This function encodes a string of bytes, containing any values whatsoever,
228in base 64 as defined in RFC 2045 (MIME) and required by the SMTP AUTH
229extension (RFC 2554). The encoding algorithm is written out in a
230straightforward way. Turning it into some kind of compact loop is messy and
231would probably run more slowly.
232
233Arguments:
234 clear points to the clear text bytes
235 len the number of bytes to encode
236
237Returns: a pointer to the zero-terminated base 64 string, which
238 is in working store
239*/
240
241static uschar *enc64table =
242 US"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
243
244uschar *
1f20760b 245b64encode(const uschar * clear, int len)
f4d091fb
JH
246{
247uschar *code = store_get(4*((len+2)/3) + 1);
248uschar *p = code;
249
250while (len-- >0)
251 {
286b9d5f 252 int x, y;
f4d091fb
JH
253
254 x = *clear++;
255 *p++ = enc64table[(x >> 2) & 63];
256
257 if (len-- <= 0)
258 {
259 *p++ = enc64table[(x << 4) & 63];
260 *p++ = '=';
261 *p++ = '=';
262 break;
263 }
264
265 y = *clear++;
266 *p++ = enc64table[((x << 4) | ((y >> 4) & 15)) & 63];
267
268 if (len-- <= 0)
269 {
270 *p++ = enc64table[(y << 2) & 63];
271 *p++ = '=';
272 break;
273 }
274
275 x = *clear++;
276 *p++ = enc64table[((y << 2) | ((x >> 6) & 3)) & 63];
277
278 *p++ = enc64table[x & 63];
279 }
280
281*p = 0;
282
283return code;
284}
285
286
287/* End of base64.c */
288/* vi: sw ai sw=2
289*/