pdns/dnsname.hh

   1 #pragma once
   2 #include <string>
   3 #include <vector>
   4 #include <set>
   5 #include <deque>
   6 #include <strings.h>
   7 #include <stdexcept>
   8
   9 // #include "dns.hh"
  10 // #include "logger.hh"
  11
  12 // #include <ext/vstring.h>
  13
  14 /* Quest in life:
  15      accept escaped ascii presentations of DNS names and store them "natively"
  16      accept a DNS packet with an offset, and extract a DNS name from it
  17      build up DNSNames with prepend and append of 'raw' unescaped labels
  18
  19    Be able to turn them into ASCII and "DNS name in a packet" again on request
  20
  21    Provide some common operators for comparison, detection of being part of another domain
  22
  23    NOTE: For now, everything MUST be . terminated, otherwise it is an error
  24 */
  25
  26
  27 class DNSName
  28 {
  29 public:
  30   DNSName() : d_empty(true), d_recurse(0) {}                 //!< Don't constructs the root name
  31   explicit DNSName(const char* p);      //!< Constructs from a human formatted, escaped presentation
  32   explicit DNSName(const std::string& str) : DNSName(str.c_str()) {}   //!< Constructs from a human formatted, escaped presentation
  33   DNSName(const char* p, int len, int offset, bool uncompress, uint16_t* qtype=0, uint16_t* qclass=0, unsigned int* consumed=0); //!< Construct from a DNS Packet, taking the first question if offset=12
  34
  35   bool isPartOf(const DNSName& rhs) const;   //!< Are we part of the rhs name?
  36   bool operator==(const DNSName& rhs) const; //!< DNS-native comparison (case insensitive)
  37   bool operator!=(const DNSName& other) const { return !(*this == other); }
  38
  39   std::string toString(const std::string& separator=".", const bool trailing=true) const;              //!< Our human-friendly, escaped, representation
  40   std::string toStringNoDot() const { return toString(".", false); }
  41   std::string toDNSString() const;           //!< Our representation in DNS native format
  42   void appendRawLabel(const std::string& str); //!< Append this unescaped label
  43   void prependRawLabel(const std::string& str); //!< Prepend this unescaped label
  44   std::vector<std::string> getRawLabels() const; //!< Individual raw unescaped labels
  45   bool chopOff();                               //!< Turn www.powerdns.com. into powerdns.com., returns false for .
  46   DNSName makeRelative(const DNSName& zone) const;
  47   DNSName labelReverse() const;
  48   bool isWildcard() const;
  49   unsigned int countLabels() const;
  50   size_t length() const; // FIXME400 remove me?
  51   bool empty() const { return d_empty; }
  52   bool isRoot() const { return !d_empty && d_storage.empty(); }
  53   void clear() { d_storage.clear(); d_empty=true; }
  54   void trimToLabels(unsigned int);
  55   DNSName& operator+=(const DNSName& rhs)
  56   {
  57     if(d_storage.size() + rhs.d_storage.size() > 254) // reserve one byte for the root label
  58       throw std::range_error("name too long");
  59
  60     d_storage+=rhs.d_storage;
  61     d_empty&=rhs.d_empty;
  62     return *this;
  63   }
  64
  65   bool operator<(const DNSName& rhs)  const // this delivers _some_ kind of ordering, but not one useful in a DNS context. Really fast though.
  66   {
  67     return std::lexicographical_compare(d_storage.rbegin(), d_storage.rend(),
  68                                  rhs.d_storage.rbegin(), rhs.d_storage.rend(),
  69                                  [](const char& a, const char& b) {
  70                                           return tolower(a) < tolower(b);
  71                                         }); // note that this is case insensitive, including on the label lengths
  72   }
  73
  74   template<class Archive>
  75   void serialize(Archive &ar, const unsigned int version)
  76   {
  77     ar & d_storage;
  78     ar & d_empty;
  79   }
  80
  81   inline bool canonCompare(const DNSName& rhs) const;
  82
  83 private:
  84   //  typedef __gnu_cxx::__sso_string string_t;
  85   typedef std::string string_t;
  86   bool slowCanonCompare(const DNSName& rhs) const;
  87   string_t d_storage;
  88   bool d_empty;
  89   int d_recurse;
  90
  91   void packetParser(const char* p, int len, int offset, bool uncompress, uint16_t* qtype=0, uint16_t* qclass=0, unsigned int* consumed=0);
  92   static std::string escapeLabel(const std::string& orig);
  93   static std::string unescapeLabel(const std::string& orig);
  94 };
  95
  96 size_t hash_value(DNSName const& d);
  97
  98 inline char dns2_tolower(char c)
  99 {
 100   if(c>='A' && c<='Z')
 101     c+='a'-'A';
 102   return c;
 103 }
 104
 105
 106 inline bool DNSName::canonCompare(const DNSName& rhs) const
 107 {
 108   //      01234567890abcd
 109   // us:  1a3www4ds9a2nl
 110   // rhs: 3www6online3com
 111   // to compare, we start at the back, is nl < com? no -> done
 112   //
 113   // 0,2,6,a
 114   // 0,4,a
 115
 116   uint8_t ourpos[64], rhspos[64];
 117   uint8_t ourcount=0, rhscount=0;
 118   //cout<<"Asked to compare "<<toString()<<" to "<<rhs.toString()<<endl;
 119   for(const char* p = d_storage.c_str(); p < d_storage.c_str() + d_storage.size() && ourcount < sizeof(ourpos); p+=*p+1)
 120     ourpos[ourcount++]=(p-d_storage.c_str());
 121   for(const char* p = rhs.d_storage.c_str(); p < rhs.d_storage.c_str() + rhs.d_storage.size() && rhscount < sizeof(rhspos); p+=*p+1)
 122     rhspos[rhscount++]=(p-rhs.d_storage.c_str());
 123
 124   if(ourcount == sizeof(ourpos) || rhscount==sizeof(rhspos)) {
 125     return slowCanonCompare(rhs);
 126   }
 127
 128   for(;;) {
 129     if(ourcount == 0 && rhscount != 0)
 130       return true;
 131     if(ourcount == 0 && rhscount == 0)
 132       return false;
 133     if(ourcount !=0 && rhscount == 0)
 134       return false;
 135     ourcount--;
 136     rhscount--;
 137
 138     /*
 139     cout<<"Going to compare: '"<<string(d_storage.c_str() + ourpos[ourcount] + 1,
 140                                         d_storage.c_str() + ourpos[ourcount] + 1 + *(d_storage.c_str() + ourpos[ourcount]))<<"'"<<endl;
 141     cout<<"Against: '"<<string(rhs.d_storage.c_str() + rhspos[rhscount] + 1,
 142                               rhs.d_storage.c_str() + rhspos[rhscount] + 1 + *(rhs.d_storage.c_str() + rhspos[rhscount]))<<"'"<<endl;
 143     */
 144     bool res=std::lexicographical_compare(
 145                                           d_storage.c_str() + ourpos[ourcount] + 1,
 146                                           d_storage.c_str() + ourpos[ourcount] + 1 + *(d_storage.c_str() + ourpos[ourcount]),
 147                                           rhs.d_storage.c_str() + rhspos[rhscount] + 1,
 148                                           rhs.d_storage.c_str() + rhspos[rhscount] + 1 + *(rhs.d_storage.c_str() + rhspos[rhscount]),
 149                                           [](const char& a, const char& b) {
 150                                             return dns2_tolower(a) < dns2_tolower(b);
 151                                           });
 152
 153     //    cout<<"Forward: "<<res<<endl;
 154     if(res)
 155       return true;
 156
 157     res=std::lexicographical_compare(     rhs.d_storage.c_str() + rhspos[rhscount] + 1,
 158                                           rhs.d_storage.c_str() + rhspos[rhscount] + 1 + *(rhs.d_storage.c_str() + rhspos[rhscount]),
 159                                           d_storage.c_str() + ourpos[ourcount] + 1,
 160                                           d_storage.c_str() + ourpos[ourcount] + 1 + *(d_storage.c_str() + ourpos[ourcount]),
 161                                           [](const char& a, const char& b) {
 162                                             return dns2_tolower(a) < dns2_tolower(b);
 163                                           });
 164     //    cout<<"Reverse: "<<res<<endl;
 165     if(res)
 166       return false;
 167   }
 168   return false;
 169 }
 170
 171
 172 struct CanonDNSNameCompare: public std::binary_function<DNSName, DNSName, bool>
 173 {
 174   bool operator()(const DNSName&a, const DNSName& b) const
 175   {
 176     return a.canonCompare(b);
 177   }
 178 };
 179
 180 inline DNSName operator+(const DNSName& lhs, const DNSName& rhs)
 181 {
 182   DNSName ret=lhs;
 183   ret += rhs;
 184   return ret;
 185 }
 186
 187 /* Quest in life: serve as a rapid block list. If you add a DNSName to a root SuffixMatchNode,
 188    anything part of that domain will return 'true' in check */
 189 struct SuffixMatchNode
 190 {
 191   SuffixMatchNode(const std::string& name_="", bool endNode_=false) : name(name_), endNode(endNode_)
 192   {}
 193   std::string name;
 194   std::string d_human;
 195   mutable std::set<SuffixMatchNode> children;
 196   mutable bool endNode;
 197   bool operator<(const SuffixMatchNode& rhs) const
 198   {
 199     return strcasecmp(name.c_str(), rhs.name.c_str()) < 0;
 200   }
 201
 202   void add(const DNSName& name)
 203   {
 204     if(!d_human.empty())
 205       d_human.append(", ");
 206     d_human += name.toString();
 207     add(name.getRawLabels());
 208   }
 209
 210   void add(std::vector<std::string> labels) const
 211   {
 212     if(labels.empty()) { // this allows insertion of the root
 213       endNode=true;
 214     }
 215     else if(labels.size()==1) {
 216       children.insert(SuffixMatchNode(*labels.begin(), true));
 217     }
 218     else {
 219       auto res=children.insert(SuffixMatchNode(*labels.rbegin(), false));
 220       labels.pop_back();
 221       res.first->add(labels);
 222     }
 223   }
 224
 225   bool check(const DNSName& name)  const
 226   {
 227     if(children.empty()) // speed up empty set
 228       return endNode;
 229     return check(name.getRawLabels());
 230   }
 231
 232   bool check(std::vector<std::string> labels) const
 233   {
 234     if(labels.empty()) // optimization
 235       return endNode;
 236
 237     SuffixMatchNode smn(*labels.rbegin());
 238     auto child = children.find(smn);
 239     if(child == children.end())
 240       return endNode;
 241     labels.pop_back();
 242     return child->check(labels);
 243   }
 244
 245   std::string toString() const
 246   {
 247     return d_human;
 248   }
 249
 250 };
 251
 252 std::ostream & operator<<(std::ostream &os, const DNSName& d);