X-Git-Url: https://gitweb.ps.run/matrix_esp_thesis/blobdiff_plain/21c6e8484b0bd05c27e5a91f2884d431926adc61..da776f86b42946715c27edd64f7558b9d5080df1:/ext/olm/src/base64.cpp diff --git a/ext/olm/src/base64.cpp b/ext/olm/src/base64.cpp new file mode 100644 index 0000000..0e195fb --- /dev/null +++ b/ext/olm/src/base64.cpp @@ -0,0 +1,187 @@ +/* Copyright 2015 OpenMarket Ltd + * + * Licensed 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 + +#include "olm/base64.h" +#include "olm/base64.hh" + +namespace { + +static const std::uint8_t ENCODE_BASE64[64] = { + 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, + 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, + 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, + 0x59, 0x5A, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, + 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, + 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, + 0x77, 0x78, 0x79, 0x7A, 0x30, 0x31, 0x32, 0x33, + 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x2B, 0x2F, +}; + +static const std::uint8_t E = -1; + +static const std::uint8_t DECODE_BASE64[128] = { +/* 0x0 0x1 0x2 0x3 0x4 0x5 0x6 0x7 0x8 0x9 0xA 0xB 0xC 0xD 0xE 0xF */ + E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, + E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, + E, E, E, E, E, E, E, E, E, E, E, 62, E, E, E, 63, + 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, E, E, E, E, E, E, + E, 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, E, E, E, E, E, + E, 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, E, E, E, E, E, +}; + +} // namespace + + +std::size_t olm::encode_base64_length( + std::size_t input_length +) { + return 4 * ((input_length + 2) / 3) + (input_length + 2) % 3 - 2; +} + +std::uint8_t * olm::encode_base64( + std::uint8_t const * input, std::size_t input_length, + std::uint8_t * output +) { + std::uint8_t const * end = input + (input_length / 3) * 3; + std::uint8_t const * pos = input; + while (pos != end) { + unsigned value = pos[0]; + value <<= 8; value |= pos[1]; + value <<= 8; value |= pos[2]; + pos += 3; + output[3] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; output[2] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; output[1] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; output[0] = ENCODE_BASE64[value]; + output += 4; + } + unsigned remainder = input + input_length - pos; + std::uint8_t * result = output; + if (remainder) { + unsigned value = pos[0]; + if (remainder == 2) { + value <<= 8; value |= pos[1]; + value <<= 2; + output[2] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; + result += 3; + } else { + value <<= 4; + result += 2; + } + output[1] = ENCODE_BASE64[value & 0x3F]; + value >>= 6; + output[0] = ENCODE_BASE64[value]; + } + return result; +} + + +std::size_t olm::decode_base64_length( + std::size_t input_length +) { + if (input_length % 4 == 1) { + return std::size_t(-1); + } else { + return 3 * ((input_length + 2) / 4) + (input_length + 2) % 4 - 2; + } +} + + +std::size_t olm::decode_base64( + std::uint8_t const * input, std::size_t input_length, + std::uint8_t * output +) { + size_t raw_length = olm::decode_base64_length(input_length); + + if (raw_length == std::size_t(-1)) { + return std::size_t(-1); + } + + std::uint8_t const * end = input + (input_length / 4) * 4; + std::uint8_t const * pos = input; + + while (pos != end) { + unsigned value = DECODE_BASE64[pos[0] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[1] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[2] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[3] & 0x7F]; + pos += 4; + output[2] = value; + value >>= 8; output[1] = value; + value >>= 8; output[0] = value; + output += 3; + } + + unsigned remainder = input + input_length - pos; + if (remainder) { + /* A base64 payload with a single byte remainder cannot occur because + * a single base64 character only encodes 6 bits, which is less than + * a full byte. Therefore, a minimum of two base64 characters are + * required to construct a single output byte and payloads with + * a remainder of 1 are illegal. + * + * Should never be the case due to length check above. + */ + assert(remainder != 1); + + unsigned value = DECODE_BASE64[pos[0] & 0x7F]; + value <<= 6; value |= DECODE_BASE64[pos[1] & 0x7F]; + if (remainder == 3) { + value <<= 6; value |= DECODE_BASE64[pos[2] & 0x7F]; + value >>= 2; + output[1] = value; + value >>= 8; + } else { + value >>= 4; + } + output[0] = value; + } + + return raw_length; +} + + +// implementations of base64.h + +size_t _olm_encode_base64_length( + size_t input_length +) { + return olm::encode_base64_length(input_length); +} + +size_t _olm_encode_base64( + uint8_t const * input, size_t input_length, + uint8_t * output +) { + uint8_t * r = olm::encode_base64(input, input_length, output); + return r - output; +} + +size_t _olm_decode_base64_length( + size_t input_length +) { + return olm::decode_base64_length(input_length); +} + +size_t _olm_decode_base64( + uint8_t const * input, size_t input_length, + uint8_t * output +) { + return olm::decode_base64(input, input_length, output); +}