pdns/ednssubnet.cc

   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 #ifdef HAVE_CONFIG_H
  23 #include "config.h"
  24 #endif
  25 #include "ednssubnet.hh"
  26 #include "dns.hh"
  27
  28 namespace {
  29         struct EDNSSubnetOptsWire
  30         {
  31                 uint16_t family;
  32                 uint8_t sourceMask;
  33                 uint8_t scopeMask;
  34         } GCCPACKATTRIBUTE;  // BRRRRR
  35
  36 }
  37
  38 bool getEDNSSubnetOptsFromString(const string& options, EDNSSubnetOpts* eso)
  39 {
  40   //cerr<<"options.size:"<<options.size()<<endl;
  41   return getEDNSSubnetOptsFromString(options.c_str(), options.length(), eso);
  42 }
  43 bool getEDNSSubnetOptsFromString(const char* options, unsigned int len, EDNSSubnetOpts* eso)
  44 {
  45   EDNSSubnetOptsWire esow;
  46   static_assert (sizeof(esow) == 4, "sizeof(EDNSSubnetOptsWire) must be 4 bytes");
  47   if(len < sizeof(esow))
  48     return false;
  49   memcpy(&esow, options, sizeof(esow));
  50   esow.family = ntohs(esow.family);
  51   //cerr<<"Family when parsing from string: "<<esow.family<<endl;
  52   ComboAddress address;
  53   unsigned int octetsin = esow.sourceMask > 0 ? (((esow.sourceMask - 1)>> 3)+1) : 0;
  54   //cerr<<"octetsin:"<<octetsin<<endl;
  55   if(esow.family == 1) {
  56     if(len != sizeof(esow)+octetsin)
  57       return false;
  58     if(octetsin > sizeof(address.sin4.sin_addr.s_addr))
  59       return false;
  60     address.reset();
  61     address.sin4.sin_family = AF_INET;
  62     if(octetsin > 0)
  63       memcpy(&address.sin4.sin_addr.s_addr, options+sizeof(esow), octetsin);
  64   } else if(esow.family == 2) {
  65     if(len != sizeof(esow)+octetsin)
  66       return false;
  67     if(octetsin > sizeof(address.sin6.sin6_addr.s6_addr))
  68       return false;
  69
  70     address.reset();
  71     address.sin4.sin_family = AF_INET6;
  72     if(octetsin > 0)
  73       memcpy(&address.sin6.sin6_addr.s6_addr, options+sizeof(esow), octetsin);
  74   }
  75   else
  76     return false;
  77   //cerr<<"Source address: "<<address.toString()<<", mask: "<<(int)esow.sourceMask<<endl;
  78   eso->source = Netmask(address, esow.sourceMask);
  79   /* 'address' has more bits set (potentially) than scopeMask. This leads to odd looking netmasks that promise
  80      more precision than they have. For this reason we truncate the address to scopeMask bits */
  81
  82   address.truncate(esow.scopeMask); // truncate will not throw for odd scopeMasks
  83   eso->scope = Netmask(address, esow.scopeMask);
  84
  85   return true;
  86 }
  87
  88 string makeEDNSSubnetOptsString(const EDNSSubnetOpts& eso)
  89 {
  90   string ret;
  91   EDNSSubnetOptsWire esow;
  92   uint16_t family = htons(eso.source.getNetwork().sin4.sin_family == AF_INET ? 1 : 2);
  93   esow.family = family;
  94   esow.sourceMask = eso.source.getBits();
  95   esow.scopeMask = eso.scope.getBits();
  96   ret.assign((const char*)&esow, sizeof(esow));
  97   int octetsout = ((esow.sourceMask - 1)>> 3)+1;
  98
  99   ComboAddress src=eso.source.getNetwork();
 100   src.truncate(esow.sourceMask);
 101
 102   if(family == htons(1))
 103     ret.append((const char*) &src.sin4.sin_addr.s_addr, octetsout);
 104   else
 105     ret.append((const char*) &src.sin6.sin6_addr.s6_addr, octetsout);
 106   return ret;
 107 }
 108