| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| #include <assert.h> |
| #include "base64.h" |
| |
| static const char bin_to_b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| |
| static const char b64_to_bin[128] = { |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, |
| 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0, |
| 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, |
| 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, |
| 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, |
| 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0 |
| }; |
| |
| // with full padding |
| // produces exactly b64_enc_len(srclen) chars |
| // no \0 termination |
| void b64_encode(const char* src, unsigned srclen, char* dst) { |
| unsigned buf = 0; |
| int pos = 2; |
| |
| while (srclen--) { |
| buf |= (unsigned char)*(src++) << ((pos--) << 3); |
| |
| if (pos < 0) { |
| *dst++ = bin_to_b64[(buf >> 18) & 0x3f]; |
| *dst++ = bin_to_b64[(buf >> 12) & 0x3f]; |
| *dst++ = bin_to_b64[(buf >> 6) & 0x3f]; |
| *dst++ = bin_to_b64[buf & 0x3f]; |
| pos = 2; |
| buf = 0; |
| } |
| } |
| if (pos != 2) { |
| *dst++ = bin_to_b64[(buf >> 18) & 0x3f]; |
| *dst++ = bin_to_b64[(buf >> 12) & 0x3f]; |
| *dst++ = (pos == 0) ? bin_to_b64[(buf >> 6) & 0x3f] : '='; |
| *dst++ = '='; |
| } |
| } |
| |
| // supports no padding or partial padding (one =) |
| // ignores invalid chars (fills zeros instead) |
| // produces exactly b64_dec_len(src, srclen) bytes |
| void b64_decode(const char* src, unsigned srclen, char* dst) { |
| unsigned buf = 0; |
| char c; |
| int bits = 0; |
| int pos = 0; |
| int pad = 0; |
| |
| while (srclen--) { |
| c = *src++; |
| if (c == ' ' || c == '\t' || c == '\n' || c == '\r') continue; |
| bits = 0; |
| if (c != '=') { |
| if (c > 0 && c < 127) bits = b64_to_bin[(int)c]; |
| } else { |
| pad++; |
| } |
| buf = (buf << 6) | bits; |
| pos++; |
| if (pos == 4) { |
| *dst++ = (buf >> 16) & 0xff; |
| if (pad < 2) *dst++ = (buf >> 8) & 0xff; |
| if (pad == 0) *dst++ = buf & 0xff; |
| buf = 0; |
| pos = 0; |
| } |
| } |
| // no padding or partial padding. pos must be 2 or 3 |
| if (pos == 2) { |
| *dst++ = (buf >> 4) & 0xff; |
| } else if (pos == 3) { |
| *dst++ = (buf >> 10) & 0xff; |
| if (pad == 0) *dst++ = (buf >> 2) & 0xff; |
| } |
| } |
| |
| // with padding |
| unsigned b64_enc_len(unsigned srclen) { |
| return ((srclen + 2) / 3) * 4; |
| } |
| |
| unsigned b64_dec_len(const char* src, unsigned srclen) { |
| unsigned pad = 0; |
| if (srclen > 0 && src[srclen - 1] == '=') pad++; |
| if (srclen > 1 && src[srclen - 2] == '=') pad++; |
| return ((srclen * 3) >> 2) - pad; |
| } |