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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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 "dnspacket.hh"
  31 #include "dns.hh"
  32 #include "qtype.hh"
  33 #include "tcpreceiver.hh"
  34 #include "ahuexception.hh"
  35 #include "statbag.hh"
  36 #include "arguments.hh"
  37 #include "sstuff.hh"
  38 #include "syncres.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(const string &ip, const char *domain, int type, bool doTCP)
  59 {
  60   DNSPacket p;
  61   p.setQuestion(Opcode::Query,domain,type);
  62   p.setRD(false);
  63   p.wrapup();
  64
  65   d_domain=domain;
  66   d_type=type;
  67   d_inaxfr=false;
  68   d_rcode=0;
  69
  70   struct sockaddr_in toaddr;
  71   struct in_addr inp;
  72   Utility::socklen_t addrlen=sizeof(toaddr);
  73   Utility::inet_aton(ip.c_str(),&inp);
  74   toaddr.sin_addr.s_addr=inp.s_addr;
  75
  76   toaddr.sin_port=htons(53);
  77   toaddr.sin_family=AF_INET;
  78
  79   int ret;
  80
  81   DTime dt;
  82   dt.set();
  83
  84   if(!doTCP) {
  85     if(asendto(p.getData(), p.len, 0, (struct sockaddr*)(&toaddr), sizeof(toaddr),p.d.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, p.d.id);
  92   }
  93   else {
  94     //    cerr<<"do tcp"<<endl;
  95     Socket s(InterNetwork, Stream);
  96     IPEndpoint ie(ip, 53);
  97     s.setNonBlocking();
  98     s.connect(ie);
  99
 100     unsigned int len=htons(p.len);
 101     char *lenP=(char*)&len;
 102     const char *msgP=p.getData();
 103     string packet=string(lenP, lenP+2)+string(msgP, msgP+p.len);
 104
 105     if(asendtcp(packet, &s) == 0) {
 106       //      cerr<<"asendtcp: timeout"<<endl;
 107       return 0;
 108     }
 109
 110     packet.clear();
 111     if(arecvtcp(packet,2, &s)==0) {
 112       //      cerr<<"arecvtcp: timeout"<<endl;
 113       return 0;
 114     }
 115
 116     memcpy(&len, packet.c_str(), 2);
 117     len=ntohs(len);
 118
 119     //    cerr<<"Now reading "<<len<<" bytes"<<endl;
 120
 121     if(arecvtcp(packet, len, &s)==0) {
 122       //      cerr<<"arecvtcp: timeout"<<endl;
 123       return 0;
 124     }
 125     if(len > d_bufsize) {
 126       d_bufsize=len;
 127       delete[] d_buf;
 128       d_buf = new unsigned char[d_bufsize];
 129     }
 130     memcpy(d_buf, packet.c_str(), len);
 131     d_len=len;
 132     ret=1;
 133   }
 134   d_usec=dt.udiff();
 135
 136   return ret;
 137 }
 138
 139
 140 LWRes::res_t LWRes::result()
 141 {
 142   DNSPacket p;
 143
 144   try {
 145     if(p.parse((char *)d_buf, d_len)<0)
 146       throw LWResException("resolver: unable to parse packet of "+itoa(d_len)+" bytes");
 147     d_aabit=p.d.aa;
 148     d_tcbit=p.d.tc;
 149     d_rcode=p.d.rcode;
 150     return p.getAnswers();
 151   }
 152   catch(...) {
 153     d_rcode=RCode::ServFail;
 154     LWRes::res_t empty;
 155     return empty;
 156   }
 157 }
 158