| 1 | /* |
| 2 | * This file is part of DisOrder |
| 3 | * Copyright (C) 2005, 2007, 2008 Richard Kettlewell |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, but |
| 11 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 |
| 18 | * USA |
| 19 | */ |
| 20 | /** @file lib/base64.c |
| 21 | * @brief Support for MIME base64 |
| 22 | */ |
| 23 | |
| 24 | #include "common.h" |
| 25 | |
| 26 | #include "mem.h" |
| 27 | #include "base64.h" |
| 28 | #include "vector.h" |
| 29 | |
| 30 | static const char mime_base64_table[] = |
| 31 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; |
| 32 | |
| 33 | /** @brief Convert MIME base64 |
| 34 | * @param s base64 data |
| 35 | * @param nsp Where to store length of converted data |
| 36 | * @return Decoded data |
| 37 | * |
| 38 | * See <a href="http://tools.ietf.org/html/rfc2045#section-6.8">RFC |
| 39 | * 2045 s6.8</a>. |
| 40 | */ |
| 41 | char *mime_base64(const char *s, size_t *nsp) { |
| 42 | return generic_base64(s, nsp, mime_base64_table); |
| 43 | } |
| 44 | |
| 45 | /** @brief Convert base64 |
| 46 | * @param s base64 data |
| 47 | * @param nsp Where to store length of converted data |
| 48 | * @param table Table of characters to use |
| 49 | * @return Decoded data |
| 50 | * |
| 51 | * @p table should consist of 65 characters. The first 64 will be used to |
| 52 | * represents the 64 digits and the 65th will be used as padding at the end |
| 53 | * (i.e. the role of '=' in RFC2045 base64). |
| 54 | */ |
| 55 | char *generic_base64(const char *s, size_t *nsp, const char *table) { |
| 56 | struct dynstr d; |
| 57 | const char *t; |
| 58 | int b[4], n, c; |
| 59 | |
| 60 | dynstr_init(&d); |
| 61 | n = 0; |
| 62 | while((c = (unsigned char)*s++)) { |
| 63 | if(c == table[64]) { |
| 64 | if(n >= 2) { |
| 65 | dynstr_append(&d, (b[0] << 2) + (b[1] >> 4)); |
| 66 | if(n == 3) |
| 67 | dynstr_append(&d, (b[1] << 4) + (b[2] >> 2)); |
| 68 | } |
| 69 | break; |
| 70 | } else if((t = strchr(table, c))) { |
| 71 | b[n++] = t - table; |
| 72 | if(n == 4) { |
| 73 | dynstr_append(&d, (b[0] << 2) + (b[1] >> 4)); |
| 74 | dynstr_append(&d, (b[1] << 4) + (b[2] >> 2)); |
| 75 | dynstr_append(&d, (b[2] << 6) + b[3]); |
| 76 | n = 0; |
| 77 | } |
| 78 | } |
| 79 | } |
| 80 | if(nsp) |
| 81 | *nsp = d.nvec; |
| 82 | dynstr_terminate(&d); |
| 83 | return d.vec; |
| 84 | } |
| 85 | |
| 86 | /** @brief Convert a binary string to MIME base64 |
| 87 | * @param s Bytes to convert |
| 88 | * @param ns Number of bytes to convert |
| 89 | * @return Encoded data |
| 90 | * |
| 91 | * This function does not attempt to split up lines. |
| 92 | * |
| 93 | * See <a href="http://tools.ietf.org/html/rfc2045#section-6.8">RFC |
| 94 | * 2045 s6.8</a>. |
| 95 | */ |
| 96 | char *mime_to_base64(const uint8_t *s, size_t ns) { |
| 97 | return generic_to_base64(s, ns, mime_base64_table); |
| 98 | } |
| 99 | |
| 100 | /** @brief Convert a binary string to base64 |
| 101 | * @param s Bytes to convert |
| 102 | * @param ns Number of bytes to convert |
| 103 | * @param table Table of characters to use |
| 104 | * @return Encoded data |
| 105 | * |
| 106 | * This function does not attempt to split up lines. |
| 107 | * |
| 108 | * @p table should consist of 65 characters. The first 64 will be used to |
| 109 | * represents the 64 digits and the 65th will be used as padding at the end |
| 110 | * (i.e. the role of '=' in RFC2045 base64). |
| 111 | */ |
| 112 | char *generic_to_base64(const uint8_t *s, size_t ns, const char *table) { |
| 113 | struct dynstr d[1]; |
| 114 | |
| 115 | dynstr_init(d); |
| 116 | while(ns >= 3) { |
| 117 | /* Input bytes with output bits: AAAAAABB BBBBCCCC CCDDDDDD */ |
| 118 | /* Output bytes with input bits: 000000 001111 111122 222222 */ |
| 119 | dynstr_append(d, table[s[0] >> 2]); |
| 120 | dynstr_append(d, table[((s[0] & 3) << 4) |
| 121 | + (s[1] >> 4)]); |
| 122 | dynstr_append(d, table[((s[1] & 15) << 2) |
| 123 | + (s[2] >> 6)]); |
| 124 | dynstr_append(d, table[s[2] & 63]); |
| 125 | ns -= 3; |
| 126 | s += 3; |
| 127 | } |
| 128 | if(ns > 0) { |
| 129 | dynstr_append(d, table[s[0] >> 2]); |
| 130 | switch(ns) { |
| 131 | case 1: |
| 132 | dynstr_append(d, table[(s[0] & 3) << 4]); |
| 133 | dynstr_append(d, table[64]); |
| 134 | dynstr_append(d, table[64]); |
| 135 | break; |
| 136 | case 2: |
| 137 | dynstr_append(d, table[((s[0] & 3) << 4) |
| 138 | + (s[1] >> 4)]); |
| 139 | dynstr_append(d, table[(s[1] & 15) << 2]); |
| 140 | dynstr_append(d, table[64]); |
| 141 | break; |
| 142 | } |
| 143 | } |
| 144 | dynstr_terminate(d); |
| 145 | return d->vec; |
| 146 | } |
| 147 | |
| 148 | /* |
| 149 | Local Variables: |
| 150 | c-basic-offset:2 |
| 151 | comment-column:40 |
| 152 | fill-column:79 |
| 153 | End: |
| 154 | */ |