net/base/base64.cc

// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/base/base64.h"

#include <algorithm>
#include <string>
#include <string_view>
#include <utility>

#include "base/containers/contains.h"
#include "base/strings/string_util.h"
#include "net/base/features.h"
#include "third_party/simdutf/simdutf.h"

namespace net {

bool SimdutfBase64Decode(std::string_view input,
                         std::string* output,
                         base::Base64DecodePolicy policy) {
  CHECK(base::FeatureList::IsEnabled(features::kSimdutfBase64Support));
  if (policy == base::Base64DecodePolicy::kStrict) {
    if (input.size() % 4 != 0) {
      // The input is not properly padded.
      return false;
    }
    if (std::ranges::any_of(input, [](char c) {
          return base::Contains(base::kInfraAsciiWhitespace, c);
        })) {
      return false;
    }
  }

  std::string decode_buf;
  decode_buf.resize(
      simdutf::maximal_binary_length_from_base64(input.data(), input.size()));
  simdutf::result r =
      simdutf::base64_to_binary(input.data(), input.size(), decode_buf.data());
  if (r.error != simdutf::error_code::SUCCESS) {
    return false;
  }
  // If this failed it would indicate we wrote OOB. It's possible for this to
  // be elided by the compiler, since writing OOB is UB.
  CHECK_LE(r.count, decode_buf.size());

  // Shrinks the buffer and makes it NUL-terminated.
  decode_buf.resize(r.count);

  *output = std::move(decode_buf);
  return true;
}


}  // namespace net