1 /* vi: set sw=4 ts=4: */
2 /*
3 * Copyright 2003, Glenn McGrath
4 * Copyright 2006, Rob Landley <rob@landley.net>
5 * Copyright 2010, Denys Vlasenko
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
8 */
9
10 #include "libbb.h"
11
12 /* Conversion table. for base 64 */
13 const char bb_uuenc_tbl_base64[65 + 1] ALIGN1 = {
14 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
15 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
16 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
17 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
18 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
19 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
20 'w', 'x', 'y', 'z', '0', '1', '2', '3',
21 '4', '5', '6', '7', '8', '9', '+', '/',
22 '=' /* termination character */,
23 '\0' /* needed for uudecode.c only */
24 };
25
26 const char bb_uuenc_tbl_std[65] ALIGN1 = {
27 '`', '!', '"', '#', '$', '%', '&', '\'',
28 '(', ')', '*', '+', ',', '-', '.', '/',
29 '0', '1', '2', '3', '4', '5', '6', '7',
30 '8', '9', ':', ';', '<', '=', '>', '?',
31 '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
32 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
33 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
34 'X', 'Y', 'Z', '[', '\\', ']', '^', '_',
35 '`' /* termination character */
36 };
37
38 /*
39 * Encode bytes at S of length LENGTH to uuencode or base64 format and place it
40 * to STORE. STORE will be 0-terminated, and must point to a writable
41 * buffer of at least 1+BASE64_LENGTH(length) bytes.
42 * where BASE64_LENGTH(len) = (4 * ((LENGTH + 2) / 3))
43 */
bb_uuencode(char * p,const void * src,int length,const char * tbl)44 void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl)
45 {
46 const unsigned char *s = src;
47
48 /* Transform the 3x8 bits to 4x6 bits */
49 while (length > 0) {
50 unsigned s1, s2;
51
52 /* Are s[1], s[2] valid or should be assumed 0? */
53 s1 = s2 = 0;
54 length -= 3; /* can be >=0, -1, -2 */
55 if (length >= -1) {
56 s1 = s[1];
57 if (length >= 0)
58 s2 = s[2];
59 }
60 *p++ = tbl[s[0] >> 2];
61 *p++ = tbl[((s[0] & 3) << 4) + (s1 >> 4)];
62 *p++ = tbl[((s1 & 0xf) << 2) + (s2 >> 6)];
63 *p++ = tbl[s2 & 0x3f];
64 s += 3;
65 }
66 /* Zero-terminate */
67 *p = '\0';
68 /* If length is -2 or -1, pad last char or two */
69 while (length) {
70 *--p = tbl[64];
71 length++;
72 }
73 }
74
75 /*
76 * Decode base64 encoded string. Stops on '\0'.
77 *
78 * Returns: pointer to the undecoded part of source.
79 * If points to '\0', then the source was fully decoded.
80 * (*pp_dst): advanced past the last written byte.
81 */
decode_base64(char ** pp_dst,const char * src)82 const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
83 {
84 char *dst = *pp_dst;
85 const char *src_tail;
86
87 while (1) {
88 unsigned char six_bit[4];
89 int count = 0;
90
91 /* Fetch up to four 6-bit values */
92 src_tail = src;
93 while (count < 4) {
94 char *table_ptr;
95 int ch;
96
97 /* Get next _valid_ character.
98 * bb_uuenc_tbl_base64[] contains this string:
99 * 0 1 2 3 4 5 6
100 * 01234567890123456789012345678901234567890123456789012345678901234
101 * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
102 */
103 do {
104 ch = *src;
105 if (ch == '\0') {
106 if (count == 0) {
107 /* Example:
108 * If we decode "QUJD <NUL>", we want
109 * to return ptr to NUL, not to ' ',
110 * because we did fully decode
111 * the string (to "ABC").
112 */
113 src_tail = src;
114 }
115 goto ret;
116 }
117 src++;
118 table_ptr = strchr(bb_uuenc_tbl_base64, ch);
119 //TODO: add BASE64_FLAG_foo to die on bad char?
120 } while (!table_ptr);
121
122 /* Convert encoded character to decimal */
123 ch = table_ptr - bb_uuenc_tbl_base64;
124
125 /* ch is 64 if char was '=', otherwise 0..63 */
126 if (ch == 64)
127 break;
128 six_bit[count] = ch;
129 count++;
130 }
131
132 /* Transform 6-bit values to 8-bit ones.
133 * count can be < 4 when we decode the tail:
134 * "eQ==" -> "y", not "y NUL NUL".
135 * Note that (count > 1) is always true,
136 * "x===" encoding is not valid:
137 * even a single zero byte encodes as "AA==".
138 * However, with current logic we come here with count == 1
139 * when we decode "==" tail.
140 */
141 if (count > 1)
142 *dst++ = six_bit[0] << 2 | six_bit[1] >> 4;
143 if (count > 2)
144 *dst++ = six_bit[1] << 4 | six_bit[2] >> 2;
145 if (count > 3)
146 *dst++ = six_bit[2] << 6 | six_bit[3];
147 /* Note that if we decode "AA==" and ate first '=',
148 * we just decoded one char (count == 2) and now we'll
149 * do the loop once more to decode second '='.
150 */
151 } /* while (1) */
152 ret:
153 *pp_dst = dst;
154 return src_tail;
155 }
156
157 /*
158 * Decode base64 encoded stream.
159 * Can stop on EOF, specified char, or on uuencode-style "====" line:
160 * flags argument controls it.
161 */
read_base64(FILE * src_stream,FILE * dst_stream,int flags)162 void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags)
163 {
164 /* Note that EOF _can_ be passed as exit_char too */
165 #define exit_char ((int)(signed char)flags)
166 #define uu_style_end (flags & BASE64_FLAG_UU_STOP)
167
168 /* uuencoded files have 61 byte lines. Use 64 byte buffer
169 * to process line at a time.
170 */
171 enum { BUFFER_SIZE = 64 };
172
173 char in_buf[BUFFER_SIZE + 2];
174 char out_buf[BUFFER_SIZE / 4 * 3 + 2];
175 char *out_tail;
176 const char *in_tail;
177 int term_seen = 0;
178 int in_count = 0;
179
180 while (1) {
181 while (in_count < BUFFER_SIZE) {
182 int ch = fgetc(src_stream);
183 if (ch == exit_char) {
184 if (in_count == 0)
185 return;
186 term_seen = 1;
187 break;
188 }
189 if (ch == EOF) {
190 term_seen = 1;
191 break;
192 }
193 /* Prevent "====" line to be split: stop if we see '\n'.
194 * We can also skip other whitespace and skirt the problem
195 * of files with NULs by stopping on any control char or space:
196 */
197 if (ch <= ' ')
198 break;
199 in_buf[in_count++] = ch;
200 }
201 in_buf[in_count] = '\0';
202
203 /* Did we encounter "====" line? */
204 if (uu_style_end && strcmp(in_buf, "====") == 0)
205 return;
206
207 out_tail = out_buf;
208 in_tail = decode_base64(&out_tail, in_buf);
209
210 fwrite(out_buf, (out_tail - out_buf), 1, dst_stream);
211
212 if (term_seen) {
213 /* Did we consume ALL characters? */
214 if (*in_tail == '\0')
215 return;
216 /* No */
217 bb_error_msg_and_die("truncated base64 input");
218 }
219
220 /* It was partial decode */
221 in_count = strlen(in_tail);
222 memmove(in_buf, in_tail, in_count);
223 }
224 }
225