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clean up EDNS situation and astoundingly weird endianness bug

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This commit is contained in:
bert hubert
2018-04-13 15:23:00 +02:00
parent d9b33de683
commit 0398d80a87
5 changed files with 76 additions and 66 deletions
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57
tdns/tdns.cc
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@ -47,39 +47,25 @@ bool processQuestion(const DNSNode& zones, DNSMessageReader& dm, const ComboAddr
DNSName qname;
DNSType qtype;
dm.getQuestion(qname, qtype);
DNSName origname=qname; // we need this for error reporting, we munch the original name
bool haveEDNS=false;
cout<<"Received a query from "<<remote.toStringWithPort()<<" for "<<qname<<" and type "<<qtype<<endl;
uint16_t newsize=0;
bool doBit=false;
haveEDNS = dm.getEDNS(&newsize, &doBit);
if(haveEDNS && newsize > sizeof(dnsheader))
response.payload.resize(newsize - sizeof(dnsheader));
try {
response.dh = dm.dh;
response.dh.id = dm.dh.id;
response.dh.ad = response.dh.ra = response.dh.aa = 0;
response.dh.qr = 1;
response.setQuestion(qname, qtype);
if(qtype == DNSType::AXFR || qtype == DNSType::IXFR) {
cout<<"Query was for AXFR or IXFR over UDP, can't do that"<<endl;
response.dh.rcode = (int)RCode::Servfail;
if(haveEDNS) {
response.putEDNS(newsize, doBit);
}
return true;
}
if(dm.dh.opcode != 0) {
cout<<"Query had non-zero opcode "<<dm.dh.opcode<<", sending NOTIMP"<<endl;
response.dh.rcode = (int)RCode::Notimp;
if(haveEDNS) {
response.putEDNS(newsize, doBit);
}
return true;
}
@ -88,9 +74,6 @@ bool processQuestion(const DNSNode& zones, DNSMessageReader& dm, const ComboAddr
if(!fnd || !fnd->zone) {
cout<<"No zone matched"<<endl;
response.dh.rcode = (uint8_t)RCode::Refused;
if(haveEDNS) {
response.putEDNS(newsize, doBit);
}
return true;
}
@ -175,19 +158,12 @@ bool processQuestion(const DNSNode& zones, DNSMessageReader& dm, const ComboAddr
}
addAdditional(bestzone, zonename, additional, response);
}
if(haveEDNS) {
response.putEDNS(newsize, doBit);
}
return true;
}
catch(std::out_of_range& e) { // exceeded packet size
cout<<"Query for '"<<origname<<"'|"<<qtype<<" got truncated"<<endl;
response.setQuestion(origname, qtype); // this resets the packet
response.dh.tc=1; response.dh.aa=0;
if(haveEDNS) {
response.putEDNS(newsize, doBit);
}
response.clearRRs();
response.dh.aa = 0; response.dh.tc = 1;
return true;
}
catch(std::exception& e) {
@ -208,11 +184,19 @@ void udpThread(ComboAddress local, Socket* sock, const DNSNode* zones)
cerr<<"Dropping non-query from "<<remote.toStringWithPort()<<endl;
continue;
}
DNSName qname;
DNSType qtype;
dm.getQuestion(qname, qtype);
DNSMessageWriter response(qname, qtype);
uint16_t newsize; bool doBit;
if(dm.getEDNS(&newsize, &doBit))
response.setEDNS(newsize, doBit);
DNSMessageWriter response;
if(processQuestion(*zones, dm, local, remote, response)) {
cout<<"Sending response with rcode "<<(RCode)response.dh.rcode <<endl;
SSendto(*sock, response.serialize(), remote);
string ret = response.serialize();
SSendto(*sock, ret, remote);
}
}
}
@ -261,15 +245,14 @@ void tcpClientThread(ComboAddress local, ComboAddress remote, int s, const DNSNo
DNSName name;
DNSType type;
dm.getQuestion(name, type);
DNSMessageWriter response(std::numeric_limits<uint16_t>::max()-sizeof(dnsheader));
DNSMessageWriter response(name, type, std::numeric_limits<uint16_t>::max());
if(type == DNSType::AXFR) {
cout<<"Should do AXFR for "<<name<<endl;
response.dh = dm.dh;
response.dh.id = dm.dh.id;
response.dh.ad = response.dh.ra = response.dh.aa = 0;
response.dh.qr = 1;
response.setQuestion(name, type);
DNSName zone;
auto fnd = zones->find(name, zone);
@ -287,7 +270,7 @@ void tcpClientThread(ComboAddress local, ComboAddress remote, int s, const DNSNo
response.putRR(DNSSection::Answer, zone, DNSType::SOA, node->rrsets[DNSType::SOA].ttl, node->rrsets[DNSType::SOA].contents[0]);
writeTCPResponse(sock, response);
response.setQuestion(zone, type);
response.clearRRs();
// send all other records
node->visit([&response,&sock,&name,&type,&zone](const DNSName& nname, const DNSNode* n) {
@ -301,7 +284,7 @@ void tcpClientThread(ComboAddress local, ComboAddress remote, int s, const DNSNo
}
catch(std::out_of_range& e) { // exceeded packet size
writeTCPResponse(sock, response);
response.setQuestion(zone, type);
response.clearRRs();
goto retry;
}
}
@ -309,7 +292,7 @@ void tcpClientThread(ComboAddress local, ComboAddress remote, int s, const DNSNo
}, zone);
writeTCPResponse(sock, response);
response.setQuestion(zone, type);
response.clearRRs();
// send SOA again
response.putRR(DNSSection::Answer, zone, DNSType::SOA, node->rrsets[DNSType::SOA].ttl, node->rrsets[DNSType::SOA].contents[0]);
@ -318,8 +301,6 @@ void tcpClientThread(ComboAddress local, ComboAddress remote, int s, const DNSNo
return;
}
else {
dm.payload.rewind();
if(processQuestion(*zones, dm, local, remote, response)) {
writeTCPResponse(sock, response);
}