/* MIT License
 *
 * Copyright (c) The c-ares project and its contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * SPDX-License-Identifier: MIT
 */
#ifndef DNS_PROTO_H
#define DNS_PROTO_H
// Utilities for processing DNS packet contents

#include "ares_setup.h"
#include "ares.h"
// Include ares internal file for DNS protocol constants
#include "ares_nameser.h"

#include <memory>
#include <string>
#include <vector>

extern "C" void arestest_strtolower(char *dest, const char *src,
                                    size_t dest_size);

namespace ares {

typedef unsigned char byte;

std::string           HexDump(std::vector<byte> data);
std::string           HexDump(const byte *data, int len);
std::string           HexDump(const char *data, int len);

std::string           StatusToString(int status);
std::string           RcodeToString(int rcode);
std::string           RRTypeToString(int rrtype);
std::string           ClassToString(int qclass);
std::string           AddressToString(const void *addr, int len);

const ares_dns_rr_t  *fetch_rr_opt(const ares_dns_record_t *rec);

// Convert DNS protocol data to strings.
// Note that these functions are not defensive; they assume
// a validly formatted input, and so should not be used on
// externally-determined inputs.
std::string           PacketToString(const std::vector<byte> &packet);
std::string QuestionToString(const std::vector<byte> &packet, const byte **data,
                             int *len);
std::string RRToString(const std::vector<byte> &packet, const byte **data,
                       int *len);


// Manipulate DNS protocol data.
void        PushInt32(std::vector<byte> *data, int value);
void        PushInt16(std::vector<byte> *data, int value);
std::vector<byte> EncodeString(const std::string &name);

struct DNSQuestion {
  DNSQuestion(const std::string &name, int rrtype, int qclass)
    : name_(name), rrtype_(rrtype), qclass_(qclass)
  {
  }

  DNSQuestion(const std::string &name, int rrtype)
    : name_(name), rrtype_(rrtype), qclass_(C_IN)
  {
  }

  virtual ~DNSQuestion()
  {
  }

  virtual std::vector<byte> data(const char              *request_name,
                                 const ares_dns_record_t *dnsrec) const;

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const
  {
    return data(nullptr, dnsrec);
  }

  virtual std::vector<byte> data() const
  {
    return data(nullptr, nullptr);
  }

  std::string name_;
  int         rrtype_;
  int         qclass_;
};

struct DNSRR : public DNSQuestion {
  DNSRR(const std::string &name, int rrtype, int qclass, int ttl)
    : DNSQuestion(name, rrtype, qclass), ttl_(ttl)
  {
  }

  DNSRR(const std::string &name, int rrtype, int ttl)
    : DNSQuestion(name, rrtype), ttl_(ttl)
  {
  }

  virtual ~DNSRR()
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const = 0;
  int                       ttl_;
};

struct DNSAddressRR : public DNSRR {
  DNSAddressRR(const std::string &name, int rrtype, int ttl, const byte *addr,
               int addrlen)
    : DNSRR(name, rrtype, ttl), addr_(addr, addr + addrlen)
  {
  }

  DNSAddressRR(const std::string &name, int rrtype, int ttl,
               const std::vector<byte> &addr)
    : DNSRR(name, rrtype, ttl), addr_(addr)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  std::vector<byte>         addr_;
};

struct DNSARR : public DNSAddressRR {
  DNSARR(const std::string &name, int ttl, const byte *addr, int addrlen)
    : DNSAddressRR(name, T_A, ttl, addr, addrlen)
  {
  }

  DNSARR(const std::string &name, int ttl, const std::vector<byte> &addr)
    : DNSAddressRR(name, T_A, ttl, addr)
  {
  }
};

struct DNSAaaaRR : public DNSAddressRR {
  DNSAaaaRR(const std::string &name, int ttl, const byte *addr, int addrlen)
    : DNSAddressRR(name, T_AAAA, ttl, addr, addrlen)
  {
  }

  DNSAaaaRR(const std::string &name, int ttl, const std::vector<byte> &addr)
    : DNSAddressRR(name, T_AAAA, ttl, addr)
  {
  }
};

struct DNSSingleNameRR : public DNSRR {
  DNSSingleNameRR(const std::string &name, int rrtype, int ttl,
                  const std::string &other)
    : DNSRR(name, rrtype, ttl), other_(other)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  std::string               other_;
};

struct DNSCnameRR : public DNSSingleNameRR {
  DNSCnameRR(const std::string &name, int ttl, const std::string &other)
    : DNSSingleNameRR(name, T_CNAME, ttl, other)
  {
  }
};

struct DNSNsRR : public DNSSingleNameRR {
  DNSNsRR(const std::string &name, int ttl, const std::string &other)
    : DNSSingleNameRR(name, T_NS, ttl, other)
  {
  }
};

struct DNSPtrRR : public DNSSingleNameRR {
  DNSPtrRR(const std::string &name, int ttl, const std::string &other)
    : DNSSingleNameRR(name, T_PTR, ttl, other)
  {
  }
};

struct DNSTxtRR : public DNSRR {
  DNSTxtRR(const std::string &name, int ttl,
           const std::vector<std::string> &txt)
    : DNSRR(name, T_TXT, ttl), txt_(txt)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  std::vector<std::string>  txt_;
};

struct DNSMxRR : public DNSRR {
  DNSMxRR(const std::string &name, int ttl, int pref, const std::string &other)
    : DNSRR(name, T_MX, ttl), pref_(pref), other_(other)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  int                       pref_;
  std::string               other_;
};

struct DNSSrvRR : public DNSRR {
  DNSSrvRR(const std::string &name, int ttl, int prio, int weight, int port,
           const std::string &target)
    : DNSRR(name, T_SRV, ttl), prio_(prio), weight_(weight), port_(port),
      target_(target)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  int                       prio_;
  int                       weight_;
  int                       port_;
  std::string               target_;
};

struct DNSUriRR : public DNSRR {
  DNSUriRR(const std::string &name, int ttl, int prio, int weight,
           const std::string &target)
    : DNSRR(name, T_URI, ttl), prio_(prio), weight_(weight), target_(target)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  int                       prio_;
  int                       weight_;
  std::string               target_;
};

struct DNSSoaRR : public DNSRR {
  DNSSoaRR(const std::string &name, int ttl, const std::string &nsname,
           const std::string &rname, int serial, int refresh, int retry,
           int expire, int minimum)
    : DNSRR(name, T_SOA, ttl), nsname_(nsname), rname_(rname), serial_(serial),
      refresh_(refresh), retry_(retry), expire_(expire), minimum_(minimum)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  std::string               nsname_;
  std::string               rname_;
  int                       serial_;
  int                       refresh_;
  int                       retry_;
  int                       expire_;
  int                       minimum_;
};

struct DNSNaptrRR : public DNSRR {
  DNSNaptrRR(const std::string &name, int ttl, int order, int pref,
             const std::string &flags, const std::string &service,
             const std::string &regexp, const std::string &replacement)
    : DNSRR(name, T_NAPTR, ttl), order_(order), pref_(pref), flags_(flags),
      service_(service), regexp_(regexp), replacement_(replacement)
  {
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  int                       order_;
  int                       pref_;
  std::string               flags_;
  std::string               service_;
  std::string               regexp_;
  std::string               replacement_;
};

struct DNSOption {
  int               code_;
  std::vector<byte> data_;
};

struct DNSOptRR : public DNSRR {
  DNSOptRR(unsigned char extrcode, unsigned char version, unsigned short flags,
           int udpsize, std::vector<byte> client_cookie,
           std::vector<byte> server_cookie, bool expect_server_cookie)
    : DNSRR("", T_OPT, static_cast<int>(udpsize),
            ((int)extrcode) << 24 | ((int)version) << 16 |
              ((int)flags) /* ttl */)
  {
    client_cookie_        = client_cookie;
    server_cookie_        = server_cookie;
    expect_server_cookie_ = expect_server_cookie;
  }

  virtual std::vector<byte> data(const ares_dns_record_t *dnsrec) const;
  std::vector<DNSOption>    opts_;
  std::vector<byte>         client_cookie_;
  std::vector<byte>         server_cookie_;
  bool                      expect_server_cookie_;
};

struct DNSPacket {
  DNSPacket()
    : qid_(0), response_(false), opcode_(O_QUERY), aa_(false), tc_(false),
      rd_(false), ra_(false), z_(false), ad_(false), cd_(false), rcode_(NOERROR)
  {
  }

  // Convenience functions that take ownership of given pointers.
  DNSPacket &add_question(DNSQuestion *q)
  {
    questions_.push_back(std::unique_ptr<DNSQuestion>(q));
    return *this;
  }

  DNSPacket &add_answer(DNSRR *q)
  {
    answers_.push_back(std::unique_ptr<DNSRR>(q));
    return *this;
  }

  DNSPacket &add_auth(DNSRR *q)
  {
    auths_.push_back(std::unique_ptr<DNSRR>(q));
    return *this;
  }

  DNSPacket &add_additional(DNSRR *q)
  {
    adds_.push_back(std::unique_ptr<DNSRR>(q));
    return *this;
  }

  // Chainable setters.
  DNSPacket &set_qid(int qid)
  {
    qid_ = qid;
    return *this;
  }

  DNSPacket &set_response(bool v = true)
  {
    response_ = v;
    return *this;
  }

  DNSPacket &set_aa(bool v = true)
  {
    aa_ = v;
    return *this;
  }

  DNSPacket &set_tc(bool v = true)
  {
    tc_ = v;
    return *this;
  }

  DNSPacket &set_rd(bool v = true)
  {
    rd_ = v;
    return *this;
  }

  DNSPacket &set_ra(bool v = true)
  {
    ra_ = v;
    return *this;
  }

  DNSPacket &set_z(bool v = true)
  {
    z_ = v;
    return *this;
  }

  DNSPacket &set_ad(bool v = true)
  {
    ad_ = v;
    return *this;
  }

  DNSPacket &set_cd(bool v = true)
  {
    cd_ = v;
    return *this;
  }

  DNSPacket &set_rcode(int rcode)
  {
    rcode_ = rcode;
    return *this;
  }

  // Return the encoded packet.
  std::vector<byte> data(const char              *request_name,
                         const ares_dns_record_t *dnsrec) const;

  std::vector<byte> data() const
  {
    return data(nullptr, nullptr);
  }

  int                                       qid_;
  bool                                      response_;
  int                                       opcode_;
  bool                                      aa_;
  bool                                      tc_;
  bool                                      rd_;
  bool                                      ra_;
  bool                                      z_;
  bool                                      ad_;
  bool                                      cd_;
  int                                       rcode_;
  std::vector<std::unique_ptr<DNSQuestion>> questions_;
  std::vector<std::unique_ptr<DNSRR>>       answers_;
  std::vector<std::unique_ptr<DNSRR>>       auths_;
  std::vector<std::unique_ptr<DNSRR>>       adds_;
};

}  // namespace ares

#endif