osp/impl/discovery/mdns/domain_name.h

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef OSP_IMPL_DISCOVERY_MDNS_DOMAIN_NAME_H_
#define OSP_IMPL_DISCOVERY_MDNS_DOMAIN_NAME_H_

#include <cstdint>
#include <ostream>
#include <string>
#include <vector>

#include "absl/strings/string_view.h"
#include "platform/base/error.h"
#include "util/osp_logging.h"

namespace openscreen {
namespace osp {

struct DomainName {
  static ErrorOr<DomainName> Append(const DomainName& first,
                                    const DomainName& second);

  template <typename It>
  static ErrorOr<DomainName> FromLabels(It first, It last) {
    size_t total_length = 1;
    for (auto label = first; label != last; ++label) {
      if (label->size() > kDomainNameMaxLabelLength)
        return Error::Code::kDomainNameLabelTooLong;

      total_length += label->size() + 1;
    }
    if (total_length > kDomainNameMaxLength)
      return Error::Code::kDomainNameTooLong;

    DomainName result;
    result.domain_name_.resize(total_length);
    auto result_it = result.domain_name_.begin();
    for (auto label = first; label != last; ++label) {
      *result_it++ = static_cast<uint8_t>(label->size());
      result_it = std::copy(label->begin(), label->end(), result_it);
    }
    *result_it = 0;
    return std::move(result);
  }

  static DomainName GetLocalDomain();

  static constexpr uint8_t kDomainNameMaxLabelLength = 63u;
  static constexpr uint16_t kDomainNameMaxLength = 256u;

  DomainName();
  explicit DomainName(std::vector<uint8_t>&& domain_name);
  DomainName(const DomainName&);
  DomainName(DomainName&&) noexcept;
  ~DomainName();
  DomainName& operator=(const DomainName&);
  DomainName& operator=(DomainName&&) noexcept;

  bool operator==(const DomainName& other) const;
  bool operator!=(const DomainName& other) const;

  bool EndsWithLocalDomain() const;
  bool IsEmpty() const { return domain_name_.size() == 1 && !domain_name_[0]; }

  Error Append(const DomainName& after);
  std::vector<absl::string_view> GetLabels() const;

  const std::vector<uint8_t>& domain_name() const { return domain_name_; }

 private:
  // RFC 1035 domain name format: sequence of 1 octet label length followed by
  // label data, ending with a 0 octet.  May not exceed 256 bytes (including
  // terminating 0).
  // For example, openscreen.org would be encoded as:
  // {10, 'o', 'p', 'e', 'n', 's', 'c', 'r', 'e', 'e', 'n',
  //   3, 'o', 'r', 'g', 0}
  std::vector<uint8_t> domain_name_;
};

class DomainNameComparator {
 public:
  bool operator()(const DomainName& a, const DomainName& b) const;
};

std::ostream& operator<<(std::ostream& os, const DomainName& domain_name);

}  // namespace osp
}  // namespace openscreen

#endif  // OSP_IMPL_DISCOVERY_MDNS_DOMAIN_NAME_H_