89 lines
2.6 KiB
C++
89 lines
2.6 KiB
C++
/*
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* Base64UrlEncode.cpp
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "fdbrpc/Base64UrlEncode.h"
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namespace base64url {
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uint8_t encodeValue(uint8_t valueIn) noexcept {
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constexpr const uint8_t encoding[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
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return encoding[valueIn];
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}
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int encode(const uint8_t* __restrict plaintextIn, int lengthIn, uint8_t* __restrict codeOut) noexcept {
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const uint8_t* plainchar = plaintextIn;
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const uint8_t* const plaintextEnd = plaintextIn + lengthIn;
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uint8_t* codechar = codeOut;
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uint8_t result = 0;
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uint8_t fragment = 0;
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while (1) {
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if (plainchar == plaintextEnd) {
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return codechar - codeOut;
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}
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// byte 1 of 3
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fragment = *plainchar++;
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result = (fragment & 0x0fc) >> 2;
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*codechar++ = encodeValue(result);
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result = (fragment & 0x003) << 4;
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if (plainchar == plaintextEnd) {
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*codechar++ = encodeValue(result);
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return codechar - codeOut;
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}
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// byte 2 of 3
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fragment = *plainchar++;
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result |= (fragment & 0x0f0) >> 4;
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*codechar++ = encodeValue(result);
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result = (fragment & 0x00f) << 2;
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if (plainchar == plaintextEnd) {
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*codechar++ = encodeValue(result);
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return codechar - codeOut;
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}
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// byte 3 of 3
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fragment = *plainchar++;
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result |= (fragment & 0x0c0) >> 6;
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*codechar++ = encodeValue(result);
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result = (fragment & 0x03f) >> 0;
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*codechar++ = encodeValue(result);
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}
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/* control should not reach here */
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return codechar - codeOut;
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}
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int encodedLength(int dataLength) noexcept {
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auto r = dataLength % 3;
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if (r == 0)
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return (dataLength / 3) * 4;
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else
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return (dataLength / 3) * 4 + r + 1;
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}
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StringRef encode(Arena& arena, StringRef plainText) {
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auto encodedLen = encodedLength(plainText.size());
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if (encodedLen <= 0)
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return StringRef();
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auto out = new (arena) uint8_t[encodedLen];
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auto actualLen = encode(plainText.begin(), plainText.size(), out);
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ASSERT_EQ(encodedLen, actualLen);
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return StringRef(out, encodedLen);
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}
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} // namespace base64url
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