dnsresult.hxx

一个著名的SIP协议栈

#if !defined(RESIP_DNSRESULT_HXX)
#define RESIP_DNSRESULT_HXX

#include <iosfwd>
#include <set>
#include <vector>
#include <deque>
#include <map>
#include <stack>

#include "resip/stack/Tuple.hxx"
#include "resip/stack/Transport.hxx"
#include "resip/stack/Uri.hxx"
#include "rutil/HeapInstanceCounter.hxx"
#include "rutil/dns/RRVip.hxx"
#include "rutil/dns/DnsStub.hxx"

#ifdef WIN32
#include <Ws2tcpip.h>
#endif

struct hostent;

namespace resip
{
class DnsInterface;
class DnsHandler;

class DnsResult : public DnsResultSink
{
   public:
      RESIP_HeapCount(DnsResult);
      DnsResult(DnsInterface& interfaceObj, DnsStub& dns, RRVip& vip, DnsHandler* handler);
      virtual ~DnsResult();

      typedef enum
      {
         Available, // A result is available now
         Pending,   // More results may be pending 
         Finished,  // No more results available and none pending
         Destroyed  // the associated transaction has been deleted
      } Type;

      typedef std::vector<Data> DataVector;

      // Starts a lookup.  Has the rules for determining the transport
      // from a uri as per rfc3263 and then does a NAPTR lookup or an A
      // lookup depending on the uri
      void lookup(const Uri& uri, const std::vector<Data> &enumSuffixes);

      // Check if there are tuples available now. Will load new tuples in if
      // necessary at a lower priority. 
      Type available();
      
      // return the next tuple available for this query. The caller should have
      // checked available() before calling next()
      Tuple next();

      // whitelist the tuple returned by next().
      void success();

      // return the target of associated query
      Data target() const { return mTarget; }
      
      // Will delete this DnsResult if no pending queries are out there or wait
      // until the pending queries get responses and then delete
      void destroy();

      // Used to store a NAPTR result
      class NAPTR
      {
         public:
            NAPTR();
            // As defined by RFC3263
            bool operator<(const NAPTR& rhs) const;

            Data key; // NAPTR record key
            
            int order;
            int pref;
            Data flags;
            Data service;
            DnsNaptrRecord::RegExp regex;
            Data replacement;
      };
      
      class SRV
      {
         public:
            SRV();
            // As defined by RFC3263, RFC2782
            bool operator<(const SRV& rhs) const;
            
            Data key; // SRV record key
            
            TransportType transport;
            int priority;
            int weight;
            int cumulativeWeight; // for picking 
            int port;
            Data target;
      };

   private:
      void lookupInternal(const Uri& uri);

      // Given a transport and port from uri, return the default port to use
      int getDefaultPort(TransportType transport, int port);
      
      void lookupHost(const Data& target);
      
      // compute the cumulative weights for the SRV entries with the lowest
      // priority, then randomly pick according to RFC2782 from the entries with
      // the lowest priority based on weights. When all entries at the lowest
      // priority are chosen, pick the next lowest priority and repeat. After an
      // SRV entry is selected, remove it from mSRVResults
      SRV retrieveSRV();
      
      // Will retrieve the next SRV record and compute the prime the mResults
      // with the appropriate Tuples. 
      void primeResults();
      
      // Some utilities for parsing dns results
      static const unsigned char* skipDNSQuestion(const unsigned char *aptr,
                                                  const unsigned char *abuf,
                                                  int alen);
   private:
      DnsInterface& mInterface;
      DnsStub& mDns;
      RRVip& mVip;
      DnsHandler* mHandler;
      int mSRVCount;
      Uri mInputUri;
      bool mDoingEnum;
      
      bool mSips;
      Data mTarget;
      Data mSrvKey;
      TransportType mTransport; // current
      int mPort; // current
      Type mType;

      //Ugly hack
      Data mPassHostFromAAAAtoA;

      void transition(Type t);      
      
      // This is where the current pending (ordered) results are stored. As they
      // are retrieved by calling next(), they are popped from the front of the list
      std::deque<Tuple> mResults;
      
      // The best NAPTR record. Only one NAPTR record will be selected
      NAPTR mPreferredNAPTR;

      // used in determining the next SRV record to use as per rfc2782
      int mCumulativeWeight; // for current priority

      // All SRV records sorted in order of preference
      std::vector<SRV> mSRVResults;
      
      friend class DnsInterface;
      friend std::ostream& operator<<(std::ostream& strm, const DnsResult&);
      friend std::ostream& operator<<(std::ostream& strm, const DnsResult::SRV&);
      friend std::ostream& operator<<(std::ostream& strm, const DnsResult::NAPTR&);

      // DnsResultSink
      void onDnsResult(const DNSResult<DnsHostRecord>&);

#ifdef USE_IPV6
      void onDnsResult(const DNSResult<DnsAAAARecord>&);
#endif

      void onDnsResult(const DNSResult<DnsSrvRecord>&);
      void onDnsResult(const DNSResult<DnsNaptrRecord>&);
      void onDnsResult(const DNSResult<DnsCnameRecord>&);

      void onEnumResult(const DNSResult<DnsNaptrRecord>& result);
      void onNaptrResult(const DNSResult<DnsNaptrRecord>& result);
      

      typedef struct
      {
            Data domain;
            int rrType;
            Data value; // stores ip for A/AAAA, target host:port for SRV, and replacement for NAPTR.
      } Item;

      std::stack<Item> mCurrResultPath;
      std::stack<Item> mCurrSuccessPath;

      void clearCurrPath();
      void addToPath(const std::deque<Tuple>& results);
      void blacklistLastReturnedResult();

      Tuple mLastReturnedResult;
      bool mBlacklistLastReturnedResult;

};

std::ostream& operator<<(std::ostream& strm, const DnsResult&);
std::ostream& operator<<(std::ostream& strm, const DnsResult::SRV&);
std::ostream& operator<<(std::ostream& strm, const DnsResult::NAPTR&);

}

#endif
//  Copyright (c) 2003, Jason Fischl 
/* ====================================================================
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 *    distribution.
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