pdns/dnsparser.hh

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #ifndef DNSPARSER_HH
  23 #define DNSPARSER_HH
  24
  25 #include <map>
  26 #include <sstream>
  27 #include <stdexcept>
  28 #include <iostream>
  29 #include <vector>
  30 #include <errno.h>
  31 // #include <netinet/in.h>
  32 #include "misc.hh"
  33
  34 #include <boost/tuple/tuple.hpp>
  35 #include <boost/tuple/tuple_comparison.hpp>
  36 #include "dns.hh"
  37 #include "dnswriter.hh"
  38 #include "dnsname.hh"
  39 #include "pdnsexception.hh"
  40
  41 /** DNS records have three representations:
  42     1) in the packet
  43     2) parsed in a class, ready for use
  44     3) in the zone
  45
  46     We should implement bidirectional transitions between 1&2 and 2&3.
  47     Currently we have: 1 -> 2
  48                        2 -> 3
  49
  50     We can add:        2 -> 1  easily by reversing the packetwriter
  51     And we might be able to reverse 2 -> 3 as well
  52 */
  53
  54 #include "namespaces.hh"
  55 #include "namespaces.hh"
  56
  57 class MOADNSException : public runtime_error
  58 {
  59 public:
  60   MOADNSException(const string& str) : runtime_error(str)
  61   {}
  62 };
  63
  64
  65 class MOADNSParser;
  66
  67 class PacketReader
  68 {
  69 public:
  70   PacketReader(const vector<uint8_t>& content)
  71     : d_pos(0), d_startrecordpos(0), d_content(content)
  72   {
  73     if(content.size() > std::numeric_limits<uint16_t>::max())
  74       throw std::out_of_range("packet too large");
  75
  76     d_recordlen = (uint16_t) content.size();
  77     not_used = 0;
  78   }
  79
  80   uint32_t get32BitInt();
  81   uint16_t get16BitInt();
  82   uint8_t get8BitInt();
  83
  84   void xfr48BitInt(uint64_t& val);
  85
  86   void xfr32BitInt(uint32_t& val)
  87   {
  88     val=get32BitInt();
  89   }
  90
  91   void xfrIP(uint32_t& val)
  92   {
  93     xfr32BitInt(val);
  94     val=htonl(val);
  95   }
  96
  97   void xfrIP6(std::string &val) {
  98     xfrBlob(val, 16);
  99   }
 100
 101   void xfrTime(uint32_t& val)
 102   {
 103     xfr32BitInt(val);
 104   }
 105
 106
 107   void xfr16BitInt(uint16_t& val)
 108   {
 109     val=get16BitInt();
 110   }
 111
 112   void xfrType(uint16_t& val)
 113   {
 114     xfr16BitInt(val);
 115   }
 116
 117
 118   void xfr8BitInt(uint8_t& val)
 119   {
 120     val=get8BitInt();
 121   }
 122
 123
 124   void xfrName(DNSName &name, bool compress=false, bool noDot=false)
 125   {
 126     name=getName();
 127   }
 128
 129   void xfrText(string &text, bool multi=false, bool lenField=true)
 130   {
 131     text=getText(multi, lenField);
 132   }
 133
 134   void xfrUnquotedText(string &text, bool lenField){
 135     text=getUnquotedText(lenField);
 136   }
 137
 138   void xfrBlob(string& blob);
 139   void xfrBlobNoSpaces(string& blob, int len);
 140   void xfrBlob(string& blob, int length);
 141   void xfrHexBlob(string& blob, bool keepReading=false);
 142
 143   static uint16_t get16BitInt(const vector<unsigned char>&content, uint16_t& pos);
 144
 145   void getDnsrecordheader(struct dnsrecordheader &ah);
 146   void copyRecord(vector<unsigned char>& dest, uint16_t len);
 147   void copyRecord(unsigned char* dest, uint16_t len);
 148
 149   DNSName getName();
 150   string getText(bool multi, bool lenField);
 151   string getUnquotedText(bool lenField);
 152
 153   uint16_t d_pos;
 154
 155   bool eof() { return true; };
 156
 157 private:
 158   uint16_t d_startrecordpos; // needed for getBlob later on
 159   uint16_t d_recordlen;      // ditto
 160   uint16_t not_used; // Aligns the whole class on 8-byte boundries
 161   const vector<uint8_t>& d_content;
 162 };
 163
 164 struct DNSRecord;
 165
 166 class DNSRecordContent
 167 {
 168 public:
 169   static std::shared_ptr<DNSRecordContent> mastermake(const DNSRecord &dr, PacketReader& pr);
 170   static std::shared_ptr<DNSRecordContent> mastermake(const DNSRecord &dr, PacketReader& pr, uint16_t opcode);
 171   static std::shared_ptr<DNSRecordContent> mastermake(uint16_t qtype, uint16_t qclass, const string& zone);
 172
 173   virtual std::string getZoneRepresentation(bool noDot=false) const = 0;
 174   virtual ~DNSRecordContent() {}
 175   virtual void toPacket(DNSPacketWriter& pw)=0;
 176   virtual string serialize(const DNSName& qname, bool canonic=false, bool lowerCase=false) // it would rock if this were const, but it is too hard
 177   {
 178     vector<uint8_t> packet;
 179     DNSPacketWriter pw(packet, g_rootdnsname, 1);
 180     if(canonic)
 181       pw.setCanonic(true);
 182
 183     if(lowerCase)
 184       pw.setLowercase(true);
 185
 186     pw.startRecord(qname, this->getType());
 187     this->toPacket(pw);
 188
 189     string record;
 190     pw.getRecordPayload(record); // needs to be called before commit()
 191     return record;
 192   }
 193
 194   virtual bool operator==(const DNSRecordContent& rhs) const
 195   {
 196     return typeid(*this)==typeid(rhs) && this->getZoneRepresentation() == rhs.getZoneRepresentation();
 197   }
 198
 199   static shared_ptr<DNSRecordContent> unserialize(const DNSName& qname, uint16_t qtype, const string& serialized);
 200
 201   void doRecordCheck(const struct DNSRecord&){}
 202
 203   typedef std::shared_ptr<DNSRecordContent> makerfunc_t(const struct DNSRecord& dr, PacketReader& pr);
 204   typedef std::shared_ptr<DNSRecordContent> zmakerfunc_t(const string& str);
 205
 206   static void regist(uint16_t cl, uint16_t ty, makerfunc_t* f, zmakerfunc_t* z, const char* name)
 207   {
 208     if(f)
 209       getTypemap()[make_pair(cl,ty)]=f;
 210     if(z)
 211       getZmakermap()[make_pair(cl,ty)]=z;
 212
 213     getT2Namemap().insert(make_pair(make_pair(cl,ty), name));
 214     getN2Typemap().insert(make_pair(name, make_pair(cl,ty)));
 215   }
 216
 217   static void unregist(uint16_t cl, uint16_t ty)
 218   {
 219     pair<uint16_t, uint16_t> key=make_pair(cl, ty);
 220     getTypemap().erase(key);
 221     getZmakermap().erase(key);
 222   }
 223
 224   static uint16_t TypeToNumber(const string& name)
 225   {
 226     n2typemap_t::const_iterator iter = getN2Typemap().find(toUpper(name));
 227     if(iter != getN2Typemap().end())
 228       return iter->second.second;
 229
 230     if(boost::starts_with(name, "TYPE") || boost::starts_with(name, "type"))
 231       return (uint16_t) pdns_stou(name.substr(4));
 232
 233     throw runtime_error("Unknown DNS type '"+name+"'");
 234   }
 235
 236   static const string NumberToType(uint16_t num, uint16_t classnum=1)
 237   {
 238     t2namemap_t::const_iterator iter = getT2Namemap().find(make_pair(classnum, num));
 239     if(iter == getT2Namemap().end())
 240       return "TYPE" + std::to_string(num);
 241       //      throw runtime_error("Unknown DNS type with numerical id "+std::to_string(num));
 242     return iter->second;
 243   }
 244
 245   virtual uint16_t getType() const = 0;
 246
 247 protected:
 248   typedef std::map<std::pair<uint16_t, uint16_t>, makerfunc_t* > typemap_t;
 249   typedef std::map<std::pair<uint16_t, uint16_t>, zmakerfunc_t* > zmakermap_t;
 250   typedef std::map<std::pair<uint16_t, uint16_t>, string > t2namemap_t;
 251   typedef std::map<string, std::pair<uint16_t, uint16_t> > n2typemap_t;
 252   static typemap_t& getTypemap();
 253   static t2namemap_t& getT2Namemap();
 254   static n2typemap_t& getN2Typemap();
 255   static zmakermap_t& getZmakermap();
 256 };
 257
 258 struct DNSRecord
 259 {
 260   DNSRecord() {
 261     d_type = 0;
 262     d_class = QClass::IN;
 263     d_ttl = 0;
 264     d_clen = 0;
 265     d_place = DNSResourceRecord::ANSWER;
 266   }
 267   explicit DNSRecord(const DNSResourceRecord& rr);
 268   DNSName d_name;
 269   std::shared_ptr<DNSRecordContent> d_content;
 270   uint16_t d_type;
 271   uint16_t d_class;
 272   uint32_t d_ttl;
 273   uint16_t d_clen;
 274   DNSResourceRecord::Place d_place;
 275
 276   bool operator<(const DNSRecord& rhs) const
 277   {
 278     if(tie(d_name, d_type, d_class, d_ttl) < tie(rhs.d_name, rhs.d_type, rhs.d_class, rhs.d_ttl))
 279       return true;
 280
 281     if(tie(d_name, d_type, d_class, d_ttl) != tie(rhs.d_name, rhs.d_type, rhs.d_class, rhs.d_ttl))
 282       return false;
 283
 284     string lzrp, rzrp;
 285     if(d_content)
 286       lzrp=toLower(d_content->getZoneRepresentation());
 287     if(rhs.d_content)
 288       rzrp=toLower(rhs.d_content->getZoneRepresentation());
 289
 290     return lzrp < rzrp;
 291   }
 292
 293   // this orders in canonical order and keeps the SOA record on top
 294   static bool prettyCompare(const DNSRecord& a, const DNSRecord& b)
 295   {
 296     auto aType = (a.d_type == QType::SOA) ? 0 : a.d_type;
 297     auto bType = (b.d_type == QType::SOA) ? 0 : b.d_type;
 298
 299     if(a.d_name.canonCompare(b.d_name))
 300       return true;
 301     if(b.d_name.canonCompare(a.d_name))
 302       return false;
 303
 304     if(tie(aType, a.d_class, a.d_ttl) < tie(bType, b.d_class, b.d_ttl))
 305       return true;
 306
 307     if(tie(aType, a.d_class, a.d_ttl) != tie(bType, b.d_class, b.d_ttl))
 308       return false;
 309
 310     string lzrp, rzrp;
 311     if(a.d_content)
 312       lzrp=toLower(a.d_content->getZoneRepresentation());
 313     if(b.d_content)
 314       rzrp=toLower(b.d_content->getZoneRepresentation());
 315
 316     return lzrp < rzrp;
 317   }
 318
 319
 320   bool operator==(const DNSRecord& rhs) const
 321   {
 322     if(d_type != rhs.d_type || d_class != rhs.d_class || d_name != rhs.d_name)
 323       return false;
 324
 325     return *d_content == *rhs.d_content;
 326   }
 327 };
 328
 329 struct DNSZoneRecord
 330 {
 331   int domain_id{-1};
 332   uint8_t scopeMask{0};
 333   int signttl{0};
 334   DNSName wildcardname;
 335   bool auth{true};
 336   DNSRecord dr;
 337 };
 338
 339
 340 //! This class can be used to parse incoming packets, and is copyable
 341 class MOADNSParser : public boost::noncopyable
 342 {
 343 public:
 344   //! Parse from a string
 345   MOADNSParser(bool query, const string& buffer)  : d_tsigPos(0)
 346   {
 347     init(query, buffer.c_str(), (unsigned int)buffer.size());
 348   }
 349
 350   //! Parse from a pointer and length
 351   MOADNSParser(bool query, const char *packet, unsigned int len) : d_tsigPos(0)
 352   {
 353     init(query, packet, len);
 354   }
 355
 356   DNSName d_qname;
 357   uint16_t d_qclass, d_qtype;
 358   //uint8_t d_rcode;
 359   dnsheader d_header;
 360
 361   typedef vector<pair<DNSRecord, uint16_t > > answers_t;
 362
 363   //! All answers contained in this packet (everything *but* the question section)
 364   answers_t d_answers;
 365
 366   shared_ptr<PacketReader> getPacketReader(uint16_t offset)
 367   {
 368     shared_ptr<PacketReader> pr(new PacketReader(d_content));
 369     pr->d_pos=offset;
 370     return pr;
 371   }
 372
 373   uint16_t getTSIGPos() const
 374   {
 375     return d_tsigPos;
 376   }
 377 private:
 378   void getDnsrecordheader(struct dnsrecordheader &ah);
 379   void init(bool query, const char *packet, unsigned int len);
 380   vector<uint8_t> d_content;
 381   uint16_t d_tsigPos;
 382 };
 383
 384 string simpleCompress(const string& label, const string& root="");
 385 void ageDNSPacket(char* packet, size_t length, uint32_t seconds);
 386 void ageDNSPacket(std::string& packet, uint32_t seconds);
 387 void editDNSPacketTTL(char* packet, size_t length, std::function<uint32_t(uint8_t, uint16_t, uint16_t, uint32_t)> visitor);
 388 uint32_t getDNSPacketMinTTL(const char* packet, size_t length);
 389 uint32_t getDNSPacketLength(const char* packet, size_t length);
 390 uint16_t getRecordsOfTypeCount(const char* packet, size_t length, uint8_t section, uint16_t type);
 391
 392 template<typename T>
 393 std::shared_ptr<T> getRR(const DNSRecord& dr)
 394 {
 395   return std::dynamic_pointer_cast<T>(dr.d_content);
 396 }
 397
 398 #endif