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shuffle nameservers we attempt to resolve

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This commit is contained in:
bert hubert 2018-10-23 09:15:35 +02:00
parent a264745605
commit 05314a06c3
1 changed files with 18 additions and 12 deletions
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30
tdns/tres.cc
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@ -353,31 +353,37 @@ ResolveResult resolveAt(const DNSName& dn, const DNSType& dt, int depth=0, const
vector<DNSName> rnsses;
for(const auto& name: nsses)
rnsses.push_back(name);
std::random_shuffle(rnsses.begin(), rnsses.end());
std::random_device rd;
std::mt19937 g(rd());
std::shuffle(rnsses.begin(), rnsses.end(), g);
for(const auto& name: rnsses) {
multimap<DNSName, ComboAddress> newns;
cout << prefix<<"Attempting to resolve NS "<<name<<endl;
for(const DNSType& qtype : {DNSType::A, DNSType::AAAA}) {
multimap<DNSName, ComboAddress> newns;
cout << prefix<<"Attempting to resolve NS " <<name<< "|"<<qtype<<endl;
try {
auto result = resolveAt(name, qtype, depth+1);
cout << prefix<<"Got "<<result.res.size()<<" nameserver " << qtype <<" addresses, adding to list"<<endl;
for(const auto& res : result.res)
newns.insert({name, getIP(res.rr)});
cout << prefix<<"We now have "<<newns.size()<<" resolved " << qtype<<" addresses to try"<<endl;
if(newns.empty())
continue;
}
catch(...)
{
cout << prefix <<"Failed to resolve name for "<<name<<"|"<<qtype<<endl;
continue;
}
// we have a new (set) of addresses to try
auto res2 = resolveAt(dn, dt, depth+1, newAuth, newns);
if(!res2.res.empty()) // it worked!
return res2;
// this could throw an NodataException or a NxdomainException, and we should let that fall through
// it didn't, let's move on to the next server
}
cout << prefix<<"We now have "<<newns.size()<<" resolved addresses to try"<<endl;
if(newns.empty())
continue;
// we have a new (set) of addresses to try
auto res2 = resolveAt(dn, dt, depth+1, newAuth, newns);
if(!res2.res.empty()) // it worked!
return res2;
// it didn't, let's move on to the next server
}
}
catch(std::exception& e) {