Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * base64.c
4 : * Encoding and decoding routines for base64 without whitespace.
5 : *
6 : * Copyright (c) 2001-2017, PostgreSQL Global Development Group
7 : *
8 : *
9 : * IDENTIFICATION
10 : * src/common/base64.c
11 : *
12 : *-------------------------------------------------------------------------
13 : */
14 :
15 : #ifndef FRONTEND
16 : #include "postgres.h"
17 : #else
18 : #include "postgres_fe.h"
19 : #endif
20 :
21 : #include "common/base64.h"
22 :
23 : /*
24 : * BASE64
25 : */
26 :
27 : static const char _base64[] =
28 : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
29 :
30 : static const int8 b64lookup[128] = {
31 : -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
32 : -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
33 : -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
34 : 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
35 : -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
36 : 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
37 : -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
38 : 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
39 : };
40 :
41 : /*
42 : * pg_b64_encode
43 : *
44 : * Encode into base64 the given string. Returns the length of the encoded
45 : * string.
46 : */
47 : int
48 6 : pg_b64_encode(const char *src, int len, char *dst)
49 : {
50 : char *p;
51 : const char *s,
52 6 : *end = src + len;
53 6 : int pos = 2;
54 6 : uint32 buf = 0;
55 :
56 6 : s = src;
57 6 : p = dst;
58 :
59 172 : while (s < end)
60 : {
61 160 : buf |= (unsigned char) *s << (pos << 3);
62 160 : pos--;
63 160 : s++;
64 :
65 : /* write it out */
66 160 : if (pos < 0)
67 : {
68 50 : *p++ = _base64[(buf >> 18) & 0x3f];
69 50 : *p++ = _base64[(buf >> 12) & 0x3f];
70 50 : *p++ = _base64[(buf >> 6) & 0x3f];
71 50 : *p++ = _base64[buf & 0x3f];
72 :
73 50 : pos = 2;
74 50 : buf = 0;
75 : }
76 : }
77 6 : if (pos != 2)
78 : {
79 6 : *p++ = _base64[(buf >> 18) & 0x3f];
80 6 : *p++ = _base64[(buf >> 12) & 0x3f];
81 6 : *p++ = (pos == 0) ? _base64[(buf >> 6) & 0x3f] : '=';
82 6 : *p++ = '=';
83 : }
84 :
85 6 : return p - dst;
86 : }
87 :
88 : /*
89 : * pg_b64_decode
90 : *
91 : * Decode the given base64 string. Returns the length of the decoded
92 : * string on success, and -1 in the event of an error.
93 : */
94 : int
95 8 : pg_b64_decode(const char *src, int len, char *dst)
96 : {
97 8 : const char *srcend = src + len,
98 8 : *s = src;
99 8 : char *p = dst;
100 : char c;
101 8 : int b = 0;
102 8 : uint32 buf = 0;
103 8 : int pos = 0,
104 8 : end = 0;
105 :
106 256 : while (s < srcend)
107 : {
108 240 : c = *s++;
109 :
110 : /* Leave if a whitespace is found */
111 240 : if (c == ' ' || c == '\t' || c == '\n' || c == '\r')
112 0 : return -1;
113 :
114 240 : if (c == '=')
115 : {
116 : /* end sequence */
117 8 : if (!end)
118 : {
119 6 : if (pos == 2)
120 2 : end = 1;
121 4 : else if (pos == 3)
122 4 : end = 2;
123 : else
124 : {
125 : /*
126 : * Unexpected "=" character found while decoding base64
127 : * sequence.
128 : */
129 0 : return -1;
130 : }
131 : }
132 8 : b = 0;
133 : }
134 : else
135 : {
136 232 : b = -1;
137 232 : if (c > 0 && c < 127)
138 232 : b = b64lookup[(unsigned char) c];
139 232 : if (b < 0)
140 : {
141 : /* invalid symbol found */
142 0 : return -1;
143 : }
144 : }
145 : /* add it to buffer */
146 240 : buf = (buf << 6) + b;
147 240 : pos++;
148 240 : if (pos == 4)
149 : {
150 60 : *p++ = (buf >> 16) & 255;
151 60 : if (end == 0 || end > 1)
152 58 : *p++ = (buf >> 8) & 255;
153 60 : if (end == 0 || end > 2)
154 54 : *p++ = buf & 255;
155 60 : buf = 0;
156 60 : pos = 0;
157 : }
158 : }
159 :
160 8 : if (pos != 0)
161 : {
162 : /*
163 : * base64 end sequence is invalid. Input data is missing padding, is
164 : * truncated or is otherwise corrupted.
165 : */
166 0 : return -1;
167 : }
168 :
169 8 : return p - dst;
170 : }
171 :
172 : /*
173 : * pg_b64_enc_len
174 : *
175 : * Returns to caller the length of the string if it were encoded with
176 : * base64 based on the length provided by caller. This is useful to
177 : * estimate how large a buffer allocation needs to be done before doing
178 : * the actual encoding.
179 : */
180 : int
181 6 : pg_b64_enc_len(int srclen)
182 : {
183 : /* 3 bytes will be converted to 4 */
184 6 : return (srclen + 2) * 4 / 3;
185 : }
186 :
187 : /*
188 : * pg_b64_dec_len
189 : *
190 : * Returns to caller the length of the string if it were to be decoded
191 : * with base64, based on the length given by caller. This is useful to
192 : * estimate how large a buffer allocation needs to be done before doing
193 : * the actual decoding.
194 : */
195 : int
196 8 : pg_b64_dec_len(int srclen)
197 : {
198 8 : return (srclen * 3) >> 2;
199 : }
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