102 lines
3.4 KiB
C++
102 lines
3.4 KiB
C++
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// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/base64url.h"
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#include <stddef.h>
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#include "base/base64.h"
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#include "base/macros.h"
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#include "base/numerics/safe_math.h"
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#include "base/strings/string_util.h"
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#include "third_party/modp_b64/modp_b64.h"
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namespace base {
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const char kPaddingChar = '=';
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// Base64url maps {+, /} to {-, _} in order for the encoded content to be safe
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// to use in a URL. These characters will be translated by this implementation.
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const char kBase64Chars[] = "+/";
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const char kBase64UrlSafeChars[] = "-_";
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void Base64UrlEncode(const StringPiece& input,
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Base64UrlEncodePolicy policy,
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std::string* output) {
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Base64Encode(input, output);
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ReplaceChars(*output, "+", "-", output);
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ReplaceChars(*output, "/", "_", output);
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switch (policy) {
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case Base64UrlEncodePolicy::INCLUDE_PADDING:
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// The padding included in |*output| will not be amended.
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break;
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case Base64UrlEncodePolicy::OMIT_PADDING:
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// The padding included in |*output| will be removed.
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const size_t last_non_padding_pos =
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output->find_last_not_of(kPaddingChar);
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if (last_non_padding_pos != std::string::npos)
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output->resize(last_non_padding_pos + 1);
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break;
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}
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}
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bool Base64UrlDecode(const StringPiece& input,
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Base64UrlDecodePolicy policy,
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std::string* output) {
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// Characters outside of the base64url alphabet are disallowed, which includes
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// the {+, /} characters found in the conventional base64 alphabet.
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if (input.find_first_of(kBase64Chars) != std::string::npos)
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return false;
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const size_t required_padding_characters = input.size() % 4;
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const bool needs_replacement =
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input.find_first_of(kBase64UrlSafeChars) != std::string::npos;
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switch (policy) {
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case Base64UrlDecodePolicy::REQUIRE_PADDING:
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// Fail if the required padding is not included in |input|.
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if (required_padding_characters > 0)
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return false;
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break;
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case Base64UrlDecodePolicy::IGNORE_PADDING:
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// Missing padding will be silently appended.
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break;
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case Base64UrlDecodePolicy::DISALLOW_PADDING:
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// Fail if padding characters are included in |input|.
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if (input.find_first_of(kPaddingChar) != std::string::npos)
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return false;
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break;
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}
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// If the string either needs replacement of URL-safe characters to normal
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// base64 ones, or additional padding, a copy of |input| needs to be made in
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// order to make these adjustments without side effects.
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if (required_padding_characters > 0 || needs_replacement) {
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std::string base64_input;
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CheckedNumeric<size_t> base64_input_size = input.size();
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if (required_padding_characters > 0)
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base64_input_size += 4 - required_padding_characters;
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base64_input.reserve(base64_input_size.ValueOrDie());
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base64_input.append(input.data(), input.size());
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// Substitute the base64url URL-safe characters to their base64 equivalents.
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ReplaceChars(base64_input, "-", "+", &base64_input);
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ReplaceChars(base64_input, "_", "/", &base64_input);
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// Append the necessary padding characters.
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base64_input.resize(base64_input_size.ValueOrDie(), '=');
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return Base64Decode(base64_input, output);
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}
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return Base64Decode(input, output);
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}
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} // namespace base
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