#include "arguments.hh"
#include "lwres.hh"
-/** Issues:
- - we need a cache pruning thing
- - case issues
- - transparency
- everything should be record=unknown except for A, MX, NS, AAAA
- - negative caching
- - compressions sucks [ortho]
-*/
typedef map<string,set<DNSResourceRecord> > cache_t;
cache_t cache;
-bool operator<(const DNSResourceRecord &a, const DNSResourceRecord &b)
-{
- if(a.qname<b.qname)
- return true;
- if(a.qname==b.qname)
- return(a.content<b.content);
- return false;
-}
-
+/** dramatis personae */
int doResolveAt(set<string> nameservers, string auth, const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret,int depth=0);
int doResolve(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth=0);
+bool doCNAMECacheCheck(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth, int &res);
+bool doCacheCheck(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth, int &res);
+void getBestNSFromCache(const string &qname, set<DNSResourceRecord>&bestns, int depth);
+void addCruft(const string &qname, vector<DNSResourceRecord>& ret);
+string getBestNSNamesFromCache(const string &qname,set<string>& nsset, int depth);
+void addAuthorityRecords(const string& qname, vector<DNSResourceRecord>& ret, int depth);
+
+/** everything begins here - this is the entry point just after receiving a packet */
+int beginResolve(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret)
+{
+ int res=doResolve(qname, qtype, ret,0);
+ if(!res)
+ addCruft(qname, ret);
+ cout<<endl;
+ return res;
+}
-string getA(const string &qname, int depth=0)
+int doResolve(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth)
{
- vector<DNSResourceRecord> res;
- string ret;
+ string prefix;
+ prefix.assign(3*depth, ' ');
+
+ int res;
+ if(doCNAMECacheCheck(qname,qtype,ret,depth,res)) // will reroute us if needed
+ return res;
- if(!doResolve(qname,QType(QType::A), res,depth+1))
- ret=res[0].content;
+ if(doCacheCheck(qname,qtype,ret,depth,res)) // we done
+ return res;
- return ret;
+ cout<<prefix<<qname<<": No cache hit for '"<<qname<<"|"<<qtype.getName()<<"', trying to find an appropriate NS record"<<endl;
+
+ string subdomain(qname);
+
+ set<string> nsset;
+ subdomain=getBestNSNamesFromCache(subdomain,nsset,depth);
+ if(!doResolveAt(nsset,subdomain,qname,qtype,ret,depth))
+ return 0;
+
+ cout<<prefix<<qname<<": failed"<<endl;
+ return RCode::ServFail;
}
-bool chopOff(string &domain)
+string getA(const string &qname, int depth=0)
{
- if(domain.empty())
- return false;
+ vector<DNSResourceRecord> res;
+ string ret;
- string::size_type fdot=domain.find('.');
+ if(!doResolve(qname,QType(QType::A), res,depth+1) && !res.empty())
+ ret=res[res.size()-1].content; // last entry, in case of CNAME in between
- if(fdot==string::npos)
- domain="";
- else
- domain=domain.substr(fdot+1);
- return true;
+ return ret;
}
-
void getBestNSFromCache(const string &qname, set<DNSResourceRecord>&bestns, int depth)
{
string prefix;
return subdomain;
}
-
-void addCruft(const string &qname, vector<DNSResourceRecord>& ret)
-{
- for(vector<DNSResourceRecord>::const_iterator k=ret.begin();k!=ret.end();++k) // don't add stuff to an NXDOMAIN!
- if(k->d_place==DNSResourceRecord::AUTHORITY && k->qtype==QType(QType::SOA))
- return;
-
- cout<<qname<<": Adding best authority records from cache"<<endl;
- addAuthorityRecords(qname,ret,0);
- cout<<qname<<": Done adding best authority records."<<endl;
-
- cout<<qname<<": Starting additional processing"<<endl;
- vector<DNSResourceRecord> addit;
- for(vector<DNSResourceRecord>::const_iterator k=ret.begin();k!=ret.end();++k)
- if((k->d_place==DNSResourceRecord::ANSWER && k->qtype==QType(QType::MX)) ||
- (k->d_place==DNSResourceRecord::AUTHORITY && k->qtype==QType(QType::NS))) {
- cout<<qname<<": record '"<<k->content<<"|"<<k->qtype.getName()<<"' needs an IP address"<<endl;
- doResolve(k->content,QType(QType::A),addit,1);
- }
-
-
- for(vector<DNSResourceRecord>::iterator k=addit.begin();k!=addit.end();++k) {
- k->d_place=DNSResourceRecord::ADDITIONAL;
- ret.push_back(*k);
- }
- cout<<qname<<": Done with additional processing"<<endl;
-}
-
-int beginResolve(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret)
-{
- int res=doResolve(qname, qtype, ret,0);
- if(!res)
- addCruft(qname, ret);
- return res;
-}
-
-bool doCNAMECheck(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth, int &res)
+bool doCNAMECacheCheck(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth, int &res)
{
string prefix, tuple=toLower(qname)+"|CNAME";
prefix.assign(3*depth, ' ');
DNSResourceRecord rr=*j;
rr.ttl-=time(0);
ret.push_back(rr);
- res=doResolve(i->second.begin()->content, qtype, ret, depth);
+ if(!(qtype==QType(QType::CNAME))) // perhaps they really wanted a CNAME!
+ res=doResolve(i->second.begin()->content, qtype, ret, depth);
return true;
}
}
return false;
}
-
-int doResolve(const string &qname, const QType &qtype, vector<DNSResourceRecord>&ret, int depth)
+inline bool moreSpecificThan(const string& a, const string &b)
{
- string prefix;
- prefix.assign(3*depth, ' ');
+ int counta=!a.empty(), countb=!b.empty();
- int res;
- if(doCNAMECheck(qname,qtype,ret,depth,res))
- return res;
-
- if(doCacheCheck(qname,qtype,ret,depth,res)) // we done
- return res;
-
- cout<<prefix<<qname<<": No cache hit for '"<<qname<<"|"<<qtype.getName()<<"', trying to find an appropriate NS record"<<endl;
-
- string subdomain(qname);
-
- do {
- set<string> nsset;
- subdomain=getBestNSNamesFromCache(subdomain,nsset,depth);
- if(!doResolveAt(nsset,subdomain,qname,qtype,ret,depth))
- return 0;
- // failed, restart at a lower level of NS
- }while(chopOff(subdomain));
-
- cout<<prefix<<qname<<": FOUND NO NS FOR '"<<subdomain<<"'"<<endl;
- return RCode::ServFail;
+ for(string::size_type n=0;n<a.size();++n)
+ if(a[n]=='.')
+ counta++;
+ for(string::size_type n=0;n<b.size();++n)
+ if(b[n]=='.')
+ countb++;
+ return counta>countb;
}
-bool endsOn(const string &domain, const string &suffix)
+inline vector<string>shuffle(set<string> &nameservers)
{
- if(domain==suffix || suffix.empty())
- return true;
- if(domain.size()<=suffix.size())
- return false;
- return (domain.substr(domain.size()-suffix.size()-1,suffix.size()+1)=="."+suffix);
+ vector<string> rnameservers;
+ for(set<string>::const_iterator i=nameservers.begin();i!=nameservers.end();++i)
+ rnameservers.push_back(*i);
+
+ random_shuffle(rnameservers.begin(),rnameservers.end());
+ return rnameservers;
}
/** returns -1 in case of no results, rcode otherwise */
LWRes r;
LWRes::res_t result;
- vector<DNSResourceRecord>usefulrrs;
- set<string> nsset;
- cout<<prefix<<qname<<": Cache consultations done, going on the wire!"<<endl;
+ cout<<prefix<<qname<<": Cache consultations done, going on the wire!"<<endl;
for(;;) { // we may get more specific nameservers
bool aabit=false;
result.clear();
- vector<string>rnameservers;
- for(set<string>::const_iterator i=nameservers.begin();i!=nameservers.end();++i)
- rnameservers.push_back(*i);
+ vector<string>rnameservers=shuffle(nameservers);
- random_shuffle(rnameservers.begin(),rnameservers.end());
- for(vector<string>::const_iterator i=rnameservers.begin();;++i){
- if(i==rnameservers.end()) {
+ for(vector<string>::const_iterator tns=rnameservers.begin();;++tns) {
+ if(tns==rnameservers.end()) {
cout<<prefix<<qname<<": Failed to resolve via any of the "<<rnameservers.size()<<" offered NS"<<endl;
return -1;
}
- cout<<prefix<<qname<<": Trying to resolve NS "<<*i<<endl;
- string remoteIP=getA(*i, depth+1);
+ cout<<prefix<<qname<<": Trying to resolve NS "<<*tns<<endl;
+ string remoteIP=getA(*tns, depth+1);
if(remoteIP.empty()) {
- cout<<prefix<<qname<<": Failed to resolve NS "<<*i<<", trying next if available"<<endl;
+ cout<<prefix<<qname<<": Failed to get IP for NS "<<*tns<<", trying next if available"<<endl;
continue;
}
- cout<<prefix<<qname<<": Resolved NS "<<*i<<" to "<<remoteIP<<", asking '"<<qname<<"|"<<qtype.getName()<<"'"<<endl;
+ cout<<prefix<<qname<<": Resolved NS "<<*tns<<" to "<<remoteIP<<", asking '"<<qname<<"|"<<qtype.getName()<<"'"<<endl;
if(r.asyncresolve(remoteIP,qname.c_str(),qtype.getCode())!=1) { // <- we go out on the wire!
- cout<<prefix<<qname<<": error resolving"<<endl;
+ cout<<prefix<<qname<<": error resolving (perhaps timeout?)"<<endl;
+ continue;
}
- else {
- result=r.result(aabit);
-
- cout<<prefix<<qname<<": Got "<<result.size()<<" answers from "<<*i<<" ("<<remoteIP<<")"<<endl;
- break;
+ result=r.result(aabit);
+ cout<<prefix<<qname<<": Got "<<result.size()<<" answers from "<<*tns<<" ("<<remoteIP<<")"<<endl;
+
+ cache_t tcache;
+ // reap all answers from this packet that are acceptable
+ for(LWRes::res_t::const_iterator i=result.begin();i!=result.end();++i) {
+ cout<<prefix<<qname<<": accept answer '"<<i->qname<<"|"<<i->qtype.getName()<<"|"<<i->content<<"' from '"<<auth<<"' nameservers? ";
+ cout.flush();
+ if(endsOn(i->qname, auth)) {
+ cout<<"YES!"<<endl;
+
+ DNSResourceRecord rr=*i;
+ rr.d_place=DNSResourceRecord::ANSWER;
+ rr.ttl+=time(0);
+ tcache[toLower(i->qname)+"|"+i->qtype.getName()].insert(rr);
+ }
+ else
+ cout<<"NO!"<<endl;
}
- }
-
-
- cache_t tcache;
- // reap all answers from this packet that are acceptable
- for(LWRes::res_t::const_iterator i=result.begin();i!=result.end();++i) {
- cout<<prefix<<qname<<": accept answer '"<<i->qname<<"|"<<i->qtype.getName()<<"|"<<i->content<<"' from '"<<auth<<"' nameservers? ";
- cout.flush();
- if(endsOn(i->qname, auth)) {
- cout<<"YES!"<<endl;
-
- DNSResourceRecord rr=*i;
- rr.d_place=DNSResourceRecord::ANSWER;
- rr.ttl+=time(0);
- tcache[toLower(i->qname)+"|"+i->qtype.getName()].insert(rr);
+
+ // supplant
+ for(cache_t::const_iterator i=tcache.begin();i!=tcache.end();++i)
+ cache[i->first]=i->second;
+
+ set<string> nsset;
+ cout<<prefix<<qname<<": determining status after receiving this packet"<<endl;
+
+ bool done=false, realreferral=false, negcache=false;
+ string newauth;
+
+ for(LWRes::res_t::const_iterator i=result.begin();i!=result.end();++i) {
+ if(i->d_place==DNSResourceRecord::AUTHORITY && endsOn(qname,i->qname) && i->qtype.getCode()==QType::SOA) {
+ cout<<prefix<<qname<<": got negative caching indication"<<endl;
+ ret.push_back(*i);
+ negcache=true;
+ }
+ else if(i->d_place==DNSResourceRecord::ANSWER && i->qname==qname && i->qtype.getCode()==QType::CNAME && (!(qtype==QType(QType::CNAME)))) {
+ cout<<prefix<<qname<<": got a CNAME referral, starting over with "<<i->content<<endl<<endl;
+ ret.push_back(*i);
+ return doResolve(i->content, qtype, ret,0);
+ }
+ // for ANY answers we *must* have an authoritive answer
+ else if(i->d_place==DNSResourceRecord::ANSWER && i->qname==qname && (i->qtype==qtype || ( qtype==QType(QType::ANY) && aabit))) {
+ cout<<prefix<<qname<<": answer is in: resolved to '"<<i->content<<"|"<<i->qtype.getName()<<"'"<<endl;
+ done=true;
+ ret.push_back(*i);
+ }
+ else if(i->d_place==DNSResourceRecord::AUTHORITY && endsOn(qname,i->qname) && i->qtype.getCode()==QType::NS) {
+ if(moreSpecificThan(i->qname,auth)) {
+ newauth=i->qname;
+ cout<<prefix<<qname<<": got NS record '"<<i->qname<<"' -> '"<<i->content<<"'"<<endl;
+ realreferral=true;
+ }
+ else {
+ cout<<prefix<<qname<<": got upwards NS record '"<<i->qname<<"' -> '"<<i->content<<"', already had '"<<auth<<"'"<<endl;
+ }
+ nsset.insert(toLower(i->content));
+ }
}
- else
- cout<<"NO!"<<endl;
- }
-
- // supplant
- for(cache_t::const_iterator i=tcache.begin();i!=tcache.end();++i)
- cache[i->first]=i->second;
-
- nsset.clear();
- cout<<prefix<<qname<<": determining status after receiving this packet"<<endl;
- bool done=false;
- for(LWRes::res_t::const_iterator i=result.begin();i!=result.end();++i) {
- if(i->d_place==DNSResourceRecord::AUTHORITY && endsOn(qname,i->qname) && i->qtype.getCode()==QType::SOA) {
- cout<<prefix<<qname<<": got a NXDOMAIN"<<endl;
- ret.push_back(*i);
- return RCode::NXDomain; // NXDOMAIN
+ if(done){
+ cout<<prefix<<qname<<": status=got results, this level of recursion done"<<endl;
+ return 0;
}
- if(i->d_place==DNSResourceRecord::ANSWER && i->qname==qname && i->qtype.getCode()==QType::CNAME) {
- cout<<prefix<<qname<<": got a CNAME referral, starting over with "<<i->content<<endl<<endl;
- ret.push_back(*i);
- return doResolve(i->content, qtype, ret,0);
+ if(r.d_rcode==RCode::NXDomain) {
+ cout<<prefix<<qname<<": status=NXDOMAIN, we are done "<<(negcache ? "(have negative SOA)" : "")<<endl;
+ return RCode::NXDomain;
}
- if(aabit && i->d_place==DNSResourceRecord::ANSWER && i->qname==qname && (i->qtype==qtype || qtype==QType(QType::ANY)) ) {
- cout<<prefix<<qname<<": answer is in: resolved to '"<<i->content<<"|"<<i->qtype.getName()<<"'"<<endl;
- done=true;
- ret.push_back(*i);
+ if(nsset.empty() && !r.d_rcode) {
+ cout<<prefix<<qname<<": status=noerror, other types may exist, but we are done "<<(negcache ? "(have negative SOA)" : "")<<endl;
+ return 0;
}
- if(i->d_place==DNSResourceRecord::AUTHORITY && i->qtype.getCode()==QType::NS) { // XXX FIXME check if suffix!
- auth=i->qname;
- cout<<prefix<<qname<<": got NS record "<<i->content<<endl;
- nsset.insert(toLower(i->content));
+ else if(realreferral) {
+ cout<<prefix<<qname<<": status=did not resolve, got "<<nsset.size()<<" NS, looping to them"<<endl;
+ auth=newauth;
+ nameservers=nsset;
+ break;
+ }
+ else {
+ cout<<prefix<<qname<<": status=NS "<<*tns<<" is lame for '"<<auth<<"', trying sibbling NS"<<endl;
}
}
- if(done){
- cout<<prefix<<qname<<": status=got results, this level of recursion done"<<endl;
- return 0;
- }
- if(nsset.empty()) {
- cout<<prefix<<qname<<": status=not resolved, did not get referral"<<endl;
- return -1;
- }
-
- cout<<prefix<<qname<<": status=did not resolve, got "<<nsset.size()<<" NS, looping to them"<<endl;
- nameservers=nsset;
}
return -1;
}
+void addCruft(const string &qname, vector<DNSResourceRecord>& ret)
+{
+ for(vector<DNSResourceRecord>::const_iterator k=ret.begin();k!=ret.end();++k) // don't add stuff to an NXDOMAIN!
+ if(k->d_place==DNSResourceRecord::AUTHORITY && k->qtype==QType(QType::SOA))
+ return;
+
+ cout<<qname<<": Adding best authority records from cache"<<endl;
+ addAuthorityRecords(qname,ret,0);
+ cout<<qname<<": Done adding best authority records."<<endl;
+
+ cout<<qname<<": Starting additional processing"<<endl;
+ vector<DNSResourceRecord> addit;
+ for(vector<DNSResourceRecord>::const_iterator k=ret.begin();k!=ret.end();++k)
+ if((k->d_place==DNSResourceRecord::ANSWER && k->qtype==QType(QType::MX)) ||
+ (k->d_place==DNSResourceRecord::AUTHORITY && k->qtype==QType(QType::NS))) {
+ cout<<qname<<": record '"<<k->content<<"|"<<k->qtype.getName()<<"' needs an IP address"<<endl;
+ doResolve(k->content,QType(QType::A),addit,1);
+ }
+
+ for(vector<DNSResourceRecord>::iterator k=addit.begin();k!=addit.end();++k) {
+ k->d_place=DNSResourceRecord::ADDITIONAL;
+ ret.push_back(*k);
+ }
+ cout<<qname<<": Done with additional processing"<<endl;
+}
+
void init(void)
{
// prime root cache
- static char*ips[]={"198.41.0.4", "128.9.0.107", "192.33.4.12", "128.8.10.90", "192.203.230.10",
- "192.5.5.241", "192.112.36.4", "128.63.2.53", "192.36.148.17",
- "198.41.0.10", "193.0.14.129", "198.32.64.12", "202.12.27.33"};
+ static char*ips[]={"198.41.0.4", "128.9.0.107", "192.33.4.12", "128.8.10.90", "192.203.230.10", "192.5.5.241", "192.112.36.4", "128.63.2.53",
+ "192.36.148.17","198.41.0.10", "193.0.14.129", "198.32.64.12", "202.12.27.33"};
DNSResourceRecord arr, nsrr;
arr.qtype=QType::A;
arr.ttl=time(0)+86400;
-
nsrr.qtype=QType::NS;
nsrr.ttl=time(0)+86400;
- nsrr.qname="";
for(char c='a';c<='m';++c) {
static char templ[40];
strncpy(templ,"a.root-servers.net", sizeof(templ) - 1);
*templ=c;
- arr.qname=templ;
+ arr.qname=nsrr.content=templ;
arr.content=ips[c-'a'];
cache[string(templ)+"|A"].insert(arr);
-
- nsrr.content=templ;
cache["|NS"].insert(nsrr);
}
}
projects / pdns / commitdiff