DNS.hh

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#ifndef COSA_INET_DNS_HH
#define COSA_INET_DNS_HH

#include "Cosa/Types.h"
#include "Cosa/Socket.hh"

class DNS {
public:
  static const uint16_t PORT = 53;

  DNS() {}

  DNS(Socket* sock, uint8_t server[4])
  {
    begin(sock, server);
  }

  ~DNS()
  {
    end();
  }

  bool begin(Socket* sock, uint8_t server[4]);

  bool end();

  int gethostbyname(const char* hostname, uint8_t ip[4])
    __attribute__((always_inline))
  {
    return (gethostbyname(hostname, ip, false));
  }

  int gethostbyname_P(str_P hostname, uint8_t ip[4])
    __attribute__((always_inline))
  {
    return (gethostbyname((const char*) hostname, ip, true));
  }

private:
  enum {
    QUERY_FLAG = (0),
    RESPONSE_FLAG = (1<<15),
    QUERY_RESPONSE_MASK = (1<<15),
    OPCODE_STANDARD_QUERY = (0),
    OPCODE_INVERSE_QUERY = (1<<11),
    OPCODE_STATUS_REQUEST = (2<<11),
    OPCODE_MASK = (15<<11),
    AUTHORITATIVE_FLAG = (1<<10),
    TRUNCATION_FLAG = (1<<9),
    RECURSION_DESIRED_FLAG = (1<<8),
    RECURSION_AVAILABLE_FLAG = (1<<7),
    RESP_NO_ERROR = (0),
    RESP_FORMAT_ERROR = (1),
    RESP_SERVER_FAILURE = (2),
    RESP_NAME_ERROR = (3),
    RESP_NOT_IMPLEMENTED = (4),
    RESP_REFUSED = (5),
    RESP_MASK = (15),
    TYPE_A = (0x0001),
    CLASS_IN = (0x0001),
    LABEL_COMPRESSION_MASK = (0xC0)
  };

  struct header_t {
    uint16_t ID;                
    uint16_t FC;                
    uint16_t QC;                
    uint16_t ANC;               
    uint16_t NSC;               
    uint16_t ARC;               
  };

  struct attr_t {
    uint16_t TYPE;              
    uint16_t CLASS;             
  };

  struct rec_t {
    uint16_t TYPE;              
    uint16_t CLASS;             
    uint32_t TTL;               
    uint16_t RDL;               
    uint8_t RD[];               
  };

  static const uint16_t TIMEOUT = 300;
  static const uint8_t RETRY_MAX = 8;
  static const uint16_t ID = 0xC05AU;
  uint8_t m_server[4];
  Socket* m_sock;

  int gethostbyname(const char* hostname, uint8_t ip[4], bool progmem);
};
#endif