pdns/lwres.cc

   1 /*
   2     PowerDNS Versatile Database Driven Nameserver
   3     Copyright (C) 2002 - 2005 PowerDNS.COM BV
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License version 2 as
   7     published by the Free Software Foundation
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18 #include "utility.hh"
  19 #include "lwres.hh"
  20 #include <pthread.h>
  21 #include <semaphore.h>
  22 #include <iostream>
  23 #include <errno.h>
  24 #include "misc.hh"
  25 #include <algorithm>
  26 #include <sstream>
  27 #include <cstring>
  28 #include <string>
  29 #include <vector>
  30 #include "dns.hh"
  31 #include "qtype.hh"
  32 #include "ahuexception.hh"
  33 #include "arguments.hh"
  34 #include "sstuff.hh"
  35 #include "syncres.hh"
  36 #include "dnswriter.hh"
  37 #include "dnsparser.hh"
  38 #include "logger.hh"
  39
  40 LWRes::LWRes()
  41 {
  42   d_sock=-1;
  43   d_timeout=500000;
  44   d_bufsize=1500;
  45   d_buf=new unsigned char[d_bufsize];
  46 }
  47
  48 LWRes::~LWRes()
  49 {
  50   if(d_sock>=0)
  51     Utility::closesocket(d_sock);
  52   delete[] d_buf;
  53 }
  54
  55
  56 //! returns -1 for permanent error, 0 for timeout, 1 for success
  57 /** Never throws! */
  58 int LWRes::asyncresolve(uint32_t ip, const char *domain, int type, bool doTCP, struct timeval* now)
  59 {
  60   d_ip=ip;
  61   vector<uint8_t> vpacket;
  62   DNSPacketWriter pw(vpacket, domain, type);
  63
  64   pw.getHeader()->rd=0;
  65   pw.getHeader()->id=random();
  66   d_domain=domain;
  67   d_type=type;
  68   d_inaxfr=false;
  69   d_rcode=0;
  70
  71
  72   struct sockaddr_in toaddr;
  73   Utility::socklen_t addrlen=sizeof(toaddr);
  74   toaddr.sin_addr.s_addr=htonl(ip);
  75
  76   toaddr.sin_port=htons(53);
  77   toaddr.sin_family=AF_INET;
  78
  79   int ret;
  80
  81   DTime dt;
  82   dt.setTimeval(*now);
  83
  84   if(!doTCP) {
  85     if(asendto((const char*)&*vpacket.begin(), vpacket.size(), 0, (struct sockaddr*)(&toaddr), sizeof(toaddr), pw.getHeader()->id)<0) {
  86       return -1;
  87     }
  88
  89     // sleep until we see an answer to this, interface to mtasker
  90
  91     ret=arecvfrom(reinterpret_cast<char *>(d_buf), d_bufsize-1,0,(struct sockaddr*)(&toaddr), &addrlen, &d_len, pw.getHeader()->id);
  92   }
  93   else {
  94     Socket s(InterNetwork, Stream);
  95     IPEndpoint ie(U32ToIP(ip), 53);
  96     s.setNonBlocking();
  97     s.connect(ie);
  98
  99     unsigned int len=htons(vpacket.size());
 100     char *lenP=(char*)&len;
 101     const char *msgP=(const char*)&*vpacket.begin();
 102     string packet=string(lenP, lenP+2)+string(msgP, msgP+vpacket.size());
 103
 104     if(asendtcp(packet, &s) == 0) {
 105       return 0;
 106     }
 107
 108     packet.clear();
 109     if(arecvtcp(packet,2, &s)==0) {
 110       return 0;
 111     }
 112
 113     memcpy(&len, packet.c_str(), 2);
 114     len=ntohs(len);
 115
 116     if(arecvtcp(packet, len, &s)==0) {
 117       return 0;
 118     }
 119     if(len > (unsigned int)d_bufsize) {
 120       d_bufsize=len;
 121       delete[] d_buf;
 122       d_buf = new unsigned char[d_bufsize];
 123     }
 124     memcpy(d_buf, packet.c_str(), len);
 125     d_len=len;
 126     ret=1;
 127   }
 128   d_usec=dt.udiff();
 129   *now=dt.getTimeval();
 130   return ret;
 131 }
 132
 133
 134 LWRes::res_t LWRes::result()
 135 {
 136   try {
 137     MOADNSParser mdp((const char*)d_buf, d_len);
 138     //    if(p.parse((char *)d_buf, d_len)<0)
 139     //      throw LWResException("resolver: unable to parse packet of "+itoa(d_len)+" bytes");
 140     d_aabit=mdp.d_header.aa;
 141     d_tcbit=mdp.d_header.tc;
 142     d_rcode=mdp.d_header.rcode;
 143
 144     if(strcasecmp(d_domain.c_str(), mdp.d_qname.c_str())) {
 145       if(d_domain.find((char)0)==string::npos) {// embedded nulls are too noisy
 146         L<<Logger::Error<<"Packet purporting to come from remote server "<<U32ToIP(d_ip)<<" contained wrong answer: '" << d_domain << "' != '" << mdp.d_qname << "'" << endl;
 147         g_stats.spoofedCount++;
 148       }
 149       goto out;
 150     }
 151
 152     LWRes::res_t ret;
 153     for(MOADNSParser::answers_t::const_iterator i=mdp.d_answers.begin(); i!=mdp.d_answers.end(); ++i) {
 154       //      cout<<i->first.d_place<<"\t"<<i->first.d_label<<"\tIN\t"<<DNSRecordContent::NumberToType(i->first.d_type);
 155       //      cout<<"\t"<<i->first.d_ttl<<"\t"<< i->first.d_content->getZoneRepresentation()<<endl;
 156       DNSResourceRecord rr;
 157       rr.qtype=i->first.d_type;
 158       rr.qname=i->first.d_label;
 159       rr.ttl=i->first.d_ttl;
 160       rr.content=i->first.d_content->getZoneRepresentation();  // this should be the serialised form
 161       rr.d_place=(DNSResourceRecord::Place) i->first.d_place;
 162       ret.push_back(rr);
 163     }
 164
 165     return ret;
 166     //    return p.getAnswers();
 167   }
 168   catch(exception &mde) {
 169     if(::arg().mustDo("log-common-errors"))
 170       L<<Logger::Error<<"Unable to parse packet from remote server: "<<mde.what()<<endl;
 171   }
 172   catch(...) {
 173     L<<Logger::Error<<"Unknown error parsing packet from remote server"<<endl;
 174   }
 175
 176   g_stats.serverParseError++;
 177
 178  out:
 179   d_rcode=RCode::ServFail;
 180   LWRes::res_t empty;
 181   return empty;
 182 }
 183