75 lines
2.1 KiB
C
75 lines
2.1 KiB
C
/* Copyright (C) 2018 C. McEnroe <june@causal.agency>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <err.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include "chat.h"
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static const char Base64[64] = {
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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};
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size_t base64Size(size_t len) {
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return 1 + (len + 2) / 3 * 4;
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}
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void base64(char *dst, const byte *src, size_t len) {
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size_t i = 0;
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while (len > 2) {
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dst[i++] = Base64[0x3F & (src[0] >> 2)];
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dst[i++] = Base64[0x3F & (src[0] << 4 | src[1] >> 4)];
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dst[i++] = Base64[0x3F & (src[1] << 2 | src[2] >> 6)];
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dst[i++] = Base64[0x3F & src[2]];
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src += 3;
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len -= 3;
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}
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if (len) {
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dst[i++] = Base64[0x3F & (src[0] >> 2)];
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if (len > 1) {
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dst[i++] = Base64[0x3F & (src[0] << 4 | src[1] >> 4)];
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dst[i++] = Base64[0x3F & (src[1] << 2)];
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} else {
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dst[i++] = Base64[0x3F & (src[0] << 4)];
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dst[i++] = '=';
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}
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dst[i++] = '=';
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}
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dst[i] = '\0';
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}
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#ifdef TEST
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#include <assert.h>
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int main() {
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assert(5 == base64Size(1));
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assert(5 == base64Size(2));
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assert(5 == base64Size(3));
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assert(9 == base64Size(4));
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char b64[base64Size(3)];
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assert((base64(b64, (byte *)"cat", 3), !strcmp("Y2F0", b64)));
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assert((base64(b64, (byte *)"ca", 2), !strcmp("Y2E=", b64)));
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assert((base64(b64, (byte *)"c", 1), !strcmp("Yw==", b64)));
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assert((base64(b64, (byte *)"\xFF\x00\xFF", 3), !strcmp("/wD/", b64)));
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assert((base64(b64, (byte *)"\x00\xFF\x00", 3), !strcmp("AP8A", b64)));
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}
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#endif
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